JP3387080B2 - Cement dispersant and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a cement dispersant used as a concrete admixture. The present invention relates to a cement dispersant which is excellent in dispersibility and dispersion persistence (change in dispersibility with time), has a short concrete hardening time, and has good strength development of concrete, and a method for producing the same.

[0002]

2. Description of the Related Art Conventional cement dispersants such as lignin sulfonic acid type, naphthalene sulfonic acid type, melamine sulfonic acid type, polycarboxylic acid type, amino sulfonic acid type dispersants have been used. Is used.

Of these, the polycarboxylic acid type dispersants are most excellent in dispersibility but inferior in dispersion sustainability (change in dispersibility with time). In order to solve this point, a polymer compound obtained by reacting a polycarboxylic acid-based polymer with a dispersant having a phenol ring has been found (JP-A-10-1344).

However, although this polymer compound is excellent in dispersibility and dispersion sustainability, it takes a long time to cure concrete. For this reason secondary concrete products (eg pole pile)
When used for applications requiring a short concrete hardening time, there is a problem that productivity and workability are significantly deteriorated. In addition, secondary concrete products and the like do not require long-term dispersion sustainability, but it is desired that concrete strength develops soon after concrete hardening. There was also a problem in this respect.

The present invention is a cement dispersant which has excellent dispersibility and dispersion sustainability for solving the above problems, has a short concrete hardening time, and has good strength development after concrete hardening, and a method for producing the same. Is provided.

[0006]

Means for Solving the Problems As a result of intensive investigations by the present inventors, the carboxylic acid (A) having an unsaturated bond, the polyoxyalkylene monomer (B) having an unsaturated bond, and the allylphenols ( C) is copolymerized in the range (parts by weight) of Formula 1, and 20 ≦ A ≦ 35, 60 ≦ B ≦ 75, 1 ≦ C ≦ 10, A + B + C = 100 Formula 1 Further formaldehyde aqueous solution (D: 37% aqueous solution equivalent) Cement dispersant containing a polymer compound as a main component obtained by reacting a melamine sulfonic acid formaldehyde condensate (E: solid content equivalent) in the ranges (parts by weight) of Formulas 2 and 3 has excellent dispersibility. It was found that the composition has long-lasting dispersion property, the hardening time of cement is short, and the strength development after hardening of concrete is good. Moreover, the manufacturing method was discovered. C ≦ D ≦ 5C Formula 2 (A + B + C): E = 4: 6 to 9: 1 Formula 3

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION As the carboxylic acid (A) having an unsaturated bond used in the present invention, acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid and the like are used, but industrially ( From the viewpoint of price), acrylic acid, methacrylic acid, and maleic acid are preferable. Also,
These can be used in appropriate combination. For example, acrylic acid and maleic acid, acrylic acid and methacrylic acid,
Methacrylic acid and maleic acid can be used in combination.

Examples of the polyoxyalkylene-based monomer (B) having an unsaturated bond include polyoxyethylene acrylate, alkoxypolyoxyethylene acrylate, polyoxyethylene methacrylate, alkoxypolyoxyethylene methacrylate, polyoxyethylene allyl ether, and alkoxy. A monomer having an oxyethylene structure such as polyoxyethylene allyl ether or a monomer having an oxypropylene structure in a part or all of the oxyethylene structure can be used.

From the industrial (price) standpoint, polyoxyethylene acrylate, methoxypolyoxyethylene methacrylate, polyoxyethylene allyl ether, and methoxypolyoxyethylene allyl ether are preferable.

These can be used in appropriate combination. For example, methoxypolyoxyethylene methacrylate and methoxypolyoxyethylene allyl ether, methoxypolyoxyethylene methacrylate and polyoxyethylene allyl ether, and polyoxyethylene methacrylate and methoxypolyoxyethylene allyl ether can be used in combination.

As the allylphenols (C), diallylbisphenols can be used in addition to allylphenol, for example, 4,4'-dihydroxydiphenylmethane, 4,4'-dihydroxydiphenylmethane.
4'-dihydroxydiphenylpropane, 3 and 3'-position allyl substitution products of 4,4'-dihydroxydiphenylsulfone, and monoallyl bisphenols such as 4,4'-dihydroxydiphenylmethane and 3,4'-dihydroxydiphenylsulfone. Allyl substitution can be used.

Copolymerization is usually carried out under aqueous conditions. In the copolymerization, the carboxylic acid (A) having an unsaturated bond, the polyoxyalkylene monomer (B) having an unsaturated bond, and the allylphenol (C) must be within the range (parts by weight) of the formula 1. There is. Outside the range of Formula 1, it becomes difficult to react with the melamine sulfonic acid formaldehyde condensate. Alternatively, the reaction product with the melamine sulfonic acid formaldehyde condensate does not show good dispersibility and dispersion sustainability.
Further, it becomes difficult to shorten the concrete hardening time. 20 ≦ A ≦ 35, 60 ≦ B ≦ 75, 1 ≦ C ≦ 10, A + B + C = 100 Formula 1

As the initiator in the copolymerization, persulfates such as ammonium persulfate, sodium persulfate and potassium persulfate, and water-soluble peroxides such as t-butyl hydroperoxide are generally used.

The copolymerization reaction is usually carried out at a reaction concentration of 10-60.
%, Reaction temperature 60 to 100 ° C., reaction time 0.5 to 20 hours.

The pH at the time of copolymerization is usually strongly acidic due to the acidity of the carboxylic acid having an unsaturated bond, but it may be adjusted to an appropriate pH. However, when a monomer having an ester bond is used as the polyoxyalkylene monomer (B) having an unsaturated bond, the pH is preferably 8 or less in order to suppress hydrolysis of the ester bond. The alkali for pH adjustment is not particularly limited, but NaOH, Ca (OH) _{2 and the} like are common.

Further, a mixture of a carboxylic acid (A) having an unsaturated bond to be copolymerized, a polyoxyalkylene monomer (B) having an unsaturated bond, and an allylphenol (C) and a polymerization initiator are used. The method of continuously adding each to the reaction vessel is suitable.

A melamine sulfonic acid formaldehyde condensate (E: solid content) is prepared by further adding a formaldehyde aqueous solution (D: 37% formaldehyde aqueous solution) to the copolymer obtained by the above-mentioned copolymerization method (hereinafter referred to as a copolymer). )
The ratio at the time of reacting with is required to be within the range (parts by weight) of Formula 2 and Formula 3. C ≦ D ≦ 5C Formula 2 (A + B + C): E = 4: 6 to 9: 1 Formula 3

Outside the ranges of the formulas 2 and 3, the reaction product of the copolymer and the melaminesulfonic acid formaldehyde condensate does not show good dispersibility and dispersion sustainability.

The formaldehyde aqueous solution used in the present invention is a general 37% formaldehyde aqueous solution.

The melamine sulfonic acid formaldehyde condensate (E) can be produced by a known method. For example, melamine is condensed with formaldehyde, and then bisulfite is added to sulfomethylate it under alkaline conditions and shrink it under weak alkaline conditions. Polymerize. Further, a condensate obtained by reacting the melamine and the bisulfite in a molar ratio of 1.0: 0.5 to 1.0: 0.9 is preferable, and the reaction product with the copolymer has good dispersibility. Show.

The reaction between the copolymer and the melamine sulfonic acid formaldehyde condensate reacts efficiently under weak alkalinity. In particular, when a monomer having an ester bond is used as the polyoxyalkylene monomer (B) having an unsaturated bond, the pH is preferably 10 or less in order to suppress hydrolysis of the ester bond. In addition, it becomes difficult to control the molecular weight under strong acidity. Therefore, a pH of 8 or higher is preferable. A particularly preferred pH is 8-9. As the alkali for pH adjustment, NaOH, Ca (OH) _{2 and the} like are generally used.

It is also possible to react a phenolic polymer during the reaction with the melamine sulfonic acid formaldehyde condensate.

Further, a method is preferred in which an aqueous copolymer solution and an aqueous melamine sulfonic acid formaldehyde condensate solution are mixed, the pH is adjusted, and then heated and the aqueous formaldehyde solution is continuously added.

The weight average molecular weight of the reaction product obtained by the above method is preferably in the range of 10,000 to 30,000. When the weight average molecular weight is lower than 10,000, the amount of low molecular weight substances that do not exhibit dispersibility increases and good dispersibility does not appear. Further, if the molecular weight is higher than 30,000, cohesiveness is exhibited and the dispersibility is adversely affected.

The weight average molecular weight can be easily measured by gel permeation chromatography (GPC).

The addition ratio of the dispersant to cement is usually 0.1 to 1.5% in terms of solid content. The dispersant of the present invention can be used in combination with known dispersants, thickeners, fluidity-retaining agents, entrained air amount regulators (AE agents, defoamers) and the like. For example, gluconic acid, lignin sulfonic acid, a cellulose derivative, a low molecular weight component obtained by subjecting a sulfurous acid pulp waste liquid to ultrafiltration treatment, polyethylene glycol and the like can be used in combination.

[0027]

According to the present invention, excellent cement dispersibility,
It has long-lasting dispersion, and the concrete hardening time is short,
It is possible to provide a cement dispersant having excellent strength development of concrete.

[0028]

EXAMPLES The present invention will be described in detail with reference to examples, but the present invention is not limited thereto. Parts in the examples are parts by weight.

Carboxylic acid having unsaturated bond (A) used, polyoxyalkylene monomer having unsaturated bond (B), allylphenol (C), aqueous formaldehyde solution (D), melaminesulfonic acid formaldehyde condensation The product (E) is shown below.
Symbol).

Carboxylic acid having unsaturated bond (A) a: Methacrylic acid b: acrylic acid c: Maleic acid

Polyoxyalkylene monomer having unsaturated bond (B) d: polyoxyethylene methacrylate (EO addition mole number = 23) e: methoxypolyoxyethylene methacrylate (EO)
Number of added moles = 9) f: Methoxypolyoxyethylene allyl ether (EO)
Number of added moles = 9) (EO: ethylene oxide)

Allylphenol (C) g: Allylphenol h: Allyl substitution of 3,4'-position of 4,4'-dihydroxydiphenylmethane i: Allyl substitution of 3,3'-position of 4,4'-dihydroxydiphenylsulfone

Formaldehyde aqueous solution (D): 37% formaldehyde aqueous solution

Melamine sulfonic acid formaldehyde condensate (E) j: Melamine 1.0 mol, and a 37% aqueous formaldehyde solution were added in an amount of 2.6 mol in terms of formaldehyde, and the mixture was reacted at a temperature of 70 ° C. for 1 hour. Next, add an aqueous solution in which 0.6 mol of sodium bisulfite is dissolved, adjust the pH to 11 with sodium hydroxide,
The reaction is carried out at a temperature of 70 ° C. for 1 hour (sulfonation). After adjusting the pH to 8 with sulfuric acid, polycondensation was carried out at a temperature of 60 ° C. for 12 hours to obtain an aqueous condensate solution. k: Melamine (1.0 mol) and 37% aqueous formaldehyde solution (2.8 mol in terms of formaldehyde) were added and reacted at a temperature of 70 ° C. for 1 hour. Next, add an aqueous solution of 0.8 mol of sodium bisulfite, adjust to pH 11 with sodium hydroxide,
The reaction is carried out at a temperature of 70 ° C. for 1 hour (sulfonation). After adjusting the pH to 8 with sulfuric acid, polycondensation was carried out at a temperature of 60 ° C. for 12 hours to obtain an aqueous condensate solution.

Copolymerization Example 1 Water was placed in a reaction vessel equipped with a stirrer, a reflux device and a dropping device.
150 parts were charged and the temperature was raised to 90 ° C. Thereafter, 35 parts of methacrylic acid (Aa), 63 parts of methoxypolyoxyethylene methacrylate (Be), 2 parts of diallyl substitution product of 4,4'-dihydroxydiphenylsulfone (Ci), and water 75
Part mixed solution and ammonium persulfate (polymerization initiator) 9
Part of water and 175 parts of water were continuously added dropwise over 2 hours to react with each other to obtain an aqueous suspension of the copolymer. [A + B + C] in the water suspension is 100 parts.

Copolymerization Examples 2 and 3 With the formulations shown in Table 1, copolymerization was carried out in the same manner as in Copolymerization Example 1 to obtain copolymer suspensions of Copolymerization Examples 2 and 3.

[0037]

[Table 1] Table 1

Example 1 Total amount of aqueous suspension of copolymer of Copolymerization Example 1 [A + B + C: 100
Parts] and 15 parts by mass of melamine sulfonic acid formaldehyde condensate (E-j) in solid content, and then adjusted to pH 9.5 with 47% NaOH aqueous solution. This mixed solution was heated to 70 ° C., 5 parts of 37% formaldehyde aqueous solution (D) was continuously added over 20 minutes, and then reacted for 20 hours to obtain an aqueous reaction solution. The weight average molecular weight of the obtained reaction product measured by GPC was 180.
00 (polyethylene glycol equivalent).

Examples 2 and 3 With the formulations shown in Table 2, the reaction was carried out in the same manner as in Example 1,
An aqueous reactant solution was obtained. The weight average molecular weight of the obtained reaction product was measured in the same manner as in Example 1 and shown in Table 3.

Comparative Examples 1 to 3 In Examples 1 to 3, the aqueous suspension of the copolymer and the aqueous solution of the melamine sulfonic acid formaldehyde condensate were simply mixed without reacting. The relationship between A, B, C and E is shown in Table 2. The weight average molecular weight of the mixture was measured in the same manner as in Example 1 and shown in Table 3.

Comparative Example 4 (Example 1 of JP-A-10-1344) 150 parts of water was charged into a reaction vessel equipped with a stirrer, a reflux device, and a dropping device, and the temperature was raised to 90 ° C. afterwards,
2,4'-dihydroxydiphenyl sulfone diallyl substitution product 2 parts, methacrylic acid 34 parts, methoxypolyoxyethylene methacrylate (EO addition mole number = 9) 64
Part, and a mixed solution of 75 parts of water, 2.2 parts of ammonium persulfate (polymerization initiator) and 175 parts of water were continuously added to the reaction vessel over 2 hours. Further, an aqueous suspension of the copolymer was obtained by reacting at 90 ° C. for 1 hour. The active ingredient [A + B + C] in the suspension is 100 parts. Total amount of aqueous suspension of copolymer obtained [(A + B + C): 100 parts]
And 50 parts of an aqueous solution of purified ligninsulfonic acid (Pearlex NL manufactured by Nippon Paper Industries Co., Ltd., solid content 30%) (solid content 1
5 parts), and then a pH of 7.
Adjusted to 6. This mixed solution was heated to 90 ° C., 5 parts of 37% aqueous formaldehyde solution was continuously added for 20 minutes, and then 9
The reaction was carried out at 0 ° C. for 20 hours to obtain a reaction product aqueous solution. The weight average molecular weight of the obtained reaction product measured by GPC is 1
It is 6000 (polyethylene glycol conversion). still,
The weight ratio of the polycarboxylic acid type polymer to the dispersant having a phenol ring is 87:13.

[0042]

[Table 2] Table 2

[0043]

[Table 3] Table 3

[Concrete Test] A concrete test was carried out for Examples 1 to 3 and Comparative Examples 1 to 4 with the formulations shown in Table 4. The concrete test was carried out according to JIS A6204.

[0045]

[Table 4] Table 4

[0046] W: water C: Cement Normal Portland cement (mixture of 3 types) Specific gravity 3.16 S: Fine aggregate, equal amount of processed sand from Hiroshima and crushed sand from Yamaguchi                           Specific gravity: 2.56 F.M 2.77 G: Coarse aggregate Yamaguchi crushed stone                           Specific gravity: 2.68 F.M 6.79 AE agent: AE-4 manufactured by Nippon Paper Industries Co., Ltd. Defoamer: Trimin DF-325 manufactured by Miyoshi Yushi Co., Ltd.

Cement, fine aggregate, coarse aggregate, water, dispersant, AE agent, and defoaming agent were put into a forced mixing mixer having a mixing amount of 50 L, and the mixture was kneaded for 90 seconds.
The solid content addition rate (based on the amount of cement) of the dispersant was adjusted to 600 ± 10 mm. The amounts of AE agent and defoaming agent were adjusted so that the amount of air in the concrete was 2.5 ± 0.5% immediately after kneading. Further, the flow value and the air amount after 30 minutes from the kneading were measured.

As for dispersibility, the flow value immediately after kneading is 600 ± 10 mm.
The dispersant has a solid content of 3%
The flow value after 0 minutes (the degree of decrease from the flow value immediately after kneading) was evaluated. The test results are shown in Table 5. Further, the concrete hardening time and the compressive strength of the concrete on the third day of age (hereinafter referred to as the three-day strength) were measured. The test results are shown in Table 6.

[0049]

[Table 5] Table 5

[0050]

[Table 6] Table 6

From Tables 5 and 6, the reaction products of Examples 1 to 3 were:
It can be seen that the dispersibility is improved as compared with the mere mixtures of Comparative Examples 1 to 3, the concrete hardening time is significantly shorter, and the strength development is good. Further, from Example 1 and Comparative Example 4, while having the dispersibility and dispersion sustainability similar to those of the cement dispersant disclosed in JP-A-10-1344, the hardening time of concrete is significantly short and the strength development is good. It can be seen that it is.

The product of the present invention can provide a cement dispersant which is excellent in cement dispersibility and dispersion sustainability, has a short concrete hardening time, and has good strength development of concrete, and a method for producing the same.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI C08G 14/10 C08G 14/10 C04B 103: 40 C04B 103: 40 (72) Inventor Masanobu Kawamura 2-8 Iida-cho, Iwakuni-shi, Yamaguchi Prefecture -1 Nippon Paper Industries Co., Ltd., Chemicals Research Laboratory (56) References JP 10-1344 (JP, A) JP 6-199918 (JP, A) JP 5-4846 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C04B 24/26 C04B 24/30 C04B 24/16-24/30 C08K 5/07 C08L 55/00 C08L 61/28 C08F 290/06 C08G 14 /Ten

Claims (5)

(57) [Claims] 1. A carboxylic acid (A) having an unsaturated bond,
Polyoxyalkylene monomer (B) having an unsaturated bond and allylphenol (C) are copolymerized in the range of Formula 1 (parts by weight), and 20 ≦ A ≦ 35, 60 ≦ B ≦ 75, 1 ≦ C ≦ 10, A + B + C = 100 Formula 1 Further, using a formaldehyde aqueous solution (D: 37% formaldehyde aqueous solution), a melaminesulfonic acid formaldehyde condensate (E: solid content) is reacted within the ranges (parts by weight) of Formula 2 and Formula 3. A cement dispersant containing a polymer compound obtained as a main component. C ≦ D ≦ 5C Formula 2 (A + B + C): E = 4: 6 to 9: 1 Formula 3 2. A condensate of melaminesulfonic acid formaldehyde condensate (E) obtained by reacting melamine and (bis) sulfite in a molar ratio of 1.0: 0.5 to 1.0: 0.9. The cement dispersant according to claim 1, which is 3. A carboxylic acid (A) having an unsaturated bond
Is a (meth) acrylic acid and / or maleic acid, The cement dispersant of Claim 1 or 2. 4. The polyoxyalkylene monomer (B) having an unsaturated bond is (methoxy) polyoxyethylene methacrylate and / or (methoxy) polyoxyethylene allyl ether.
The cement dispersant according to the item. 5. A carboxylic acid (A) having an unsaturated bond,
Polyoxyalkylene monomer (B) having an unsaturated bond and allylphenol (C) are copolymerized in the range of Formula 1 (parts by weight), and 20 ≦ A ≦ 35, 60 ≦ B ≦ 75, 1 ≦ C ≦ 10, A + B + C = 100 Formula 1 Furthermore, a formaldehyde aqueous solution (D: 37% aqueous solution equivalent) is used to react a melamine sulfonic acid formaldehyde condensate (E: solid content equivalent) within the range of Formula 2 and Formula 3 (parts by weight). A method for producing a cement dispersant containing the polymer compound obtained as a main component. C ≦ D ≦ 5C Formula 2 (A + B + C): E = 4: 6 to 9: 1 Formula 3