JPH101344A - Cement dispersant and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a cement dispersant having extremely superior dispersing ability and excellent also in dispersion sustaining property. SOLUTION: This cement dispersant is based on a high molecular compd. obtd. by copolymerizing 20-35 pts.wt. carboxylic acid (A) having an unsatd. bond with 60-75 pts.wt. polyoxyalkylene monomer having unsatd. bonds and 1-10 pts.wt. allylphenol (C) and allowing the resultant copolymer to reactor with a dispersant (E) having a phenol ring by means of an aq. formabledyde soln. (D). The total amt. of the components A, B, C is 100 pts.wt. the amt. (pts.wt.) of the component D (corresponding to 37% aq.soln.) is 1-5 times that of the component C and the ratio (pts.wt.) of (A+B+C):E (corresponding to solid matter) is (1:8) to (9:1).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a cement dispersant used as an admixture for concrete. Has particularly excellent dispersibility, and furthermore, dispersion persistence (time-dependent change in dispersibility)
And a method for producing the same.

[0002]

BACKGROUND OF THE INVENTION Conventional cement dispersants include lignin sulfonic acid type, naphthalene sulfonic acid type, melamine sulfonic acid type, polycarboxylic acid type and amino sulfonic acid type dispersants. Is used.

Among these, polycarboxylic acid-based dispersants include copolymers of (meth) acrylic acid and (meth) acrylic acid ester (Japanese Patent Publication No. 59-18338), maleic anhydride (anhydride) and the like. Copolymers of alkylene derivatives (JP-A-63-285140) are typical, and have the best dispersibility as compared with other dispersants such as ligninsulfonic acid.

However, this polycarboxylic acid-based dispersant is excellent in dispersibility, but insufficient in dispersion persistence, and various methods have been proposed to improve this point. At present, the dispersibility is reduced in order to improve the dispersibility (JP-A-7-33495).
No.).

[0005] The present invention provides a cement dispersant having excellent dispersibility and long-lasting dispersion which solves the above problems, and a method for producing the same.

[0006]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a carboxylic acid having an unsaturated bond (A), a polyoxyalkylene monomer having an unsaturated bond (B), an allylphenol ( C) is copolymerized in the range of formula 1 (parts by weight), 20 ≦ A ≦ 35, 60 ≦ B ≦ 75, 1 ≦ C ≦ 10, A + B + C = 100 Formula 1 Further, an aqueous formaldehyde solution (D: equivalent to a 37% aqueous solution)
A cement dispersant containing a polymer compound as a main component obtained by reacting a dispersant having a phenol ring (E: corresponding to a solid content) in the range of Formulas 2 and 3 (parts by weight) using It has been found that it has excellent dispersibility and is also excellent in dispersion persistence. C ≦ D ≦ 5C Equation 2 (A + B + C): E = 2: 8 to 9: 1 Equation 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. From a (price) perspective,
Acrylic acid, methacrylic acid and maleic acid are preferred. These can be used in appropriate combination. For example, acrylic acid and maleic acid, acrylic acid and methacrylic acid, and methacrylic acid and maleic acid can be used in combination.

Examples of the polyoxyalkylene monomer (B) having an unsaturated bond include polyoxyethylene acrylate, alkoxy polyoxyethylene acrylate, polyoxyethylene methacrylate, alkoxy polyoxyethylene methacrylate, polyoxyethylene allyl ether, and alkoxy. Monomers having an oxyethylene structure, such as polyoxyethylene allyl ether, and monomers having a part or all of the oxyethylene structure having an oxypropylene structure can be used. In particular, from an industrial (price) viewpoint, polyoxyethylene methacrylate, methoxypolyoxyethylene methacrylate, polyoxyethylene allyl ether, and methoxypolyoxyethylene allyl ether are preferred. These can be used in appropriate combination. For example, methoxy polyoxyethylene methacrylate and methoxy polyoxyethylene allyl ether, methoxy polyoxyethylene methacrylate and polyoxyethylene allyl ether, polyoxyethylene methacrylate and polyoxyethylene allyl ether, polyoxyethylene methacrylate and methoxy polyoxyethylene allyl ether Can be used in combination.

Further, allylphenols (C) are

Embedded image Diallyl bisphenols represented by, for example, 4,4 ′
-Dihydroxydiphenylpropane, 4,4'-dihydroxydiphenylmethane, 3,4'-allyl-substituted 4,4'-dihydroxydiphenylsulfone,

Embedded image Monoallyl bisphenols represented by, for example, 4,
4'-dihydroxydiphenylpropane, 4,4'-dihydroxydiphenylmethane, 3-position allyl substitution of 4,4'-dihydroxydiphenylsulfone, and

Embedded image Allyl phenol represented by

In the copolymerization, the carboxylic acid having an unsaturated bond (A), the polyoxyalkylene monomer having an unsaturated bond (B), and the allylphenol (C) are in the range (parts by weight) of the formula (1). Need to be. Outside the range of Equation 1,
Reaction with a dispersant having a phenol ring becomes difficult. Alternatively, a reaction product with a dispersant having a phenol ring does not show good dispersibility and dispersion persistence. 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 usually has a reaction concentration of 10 to 10.
60%, reaction temperature 60-100 ° C, reaction time 0.5-
Perform in 20 hours.

The pH at the time of copolymerization usually becomes 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-based monomer (B) having an unsaturated bond, the pH is preferably 8 or less to suppress hydrolysis of the ester bond. Although there is no particular limitation on the alkali for pH adjustment, NaOH, Ca
(OH) _{2 and the} like are common.

A mixture of a carboxylic acid having an unsaturated bond to be copolymerized (A), a polyoxyalkylene monomer having an unsaturated bond (B), and an allylphenol (C), and a polymerization initiator are used. It is appropriate to add them continuously to the reaction vessel.

The copolymer obtained by the above copolymerization method (hereinafter referred to as a copolymer) is further reacted with a dispersant (E) having a phenol ring using an aqueous formaldehyde solution (D: equivalent to a 37% aqueous solution). The method is described below.

The ratios of the copolymer (A + B + C), the aqueous formaldehyde solution (D: equivalent to a 37% aqueous solution) and the dispersant having a phenol ring (E: equivalent to the solid content) are represented by Formulas 2 and 3.
(Parts by weight). C ≦ D ≦ 5C Equation 2 (A + B + C): E = 2: 8 to 9: 1 Equation 3

Outside the range of the formulas 2 and 3, the reaction product of the copolymer and the dispersant having a phenol ring does not show good dispersibility and dispersion sustainability.

The aqueous formaldehyde solution used in the present invention is a 37% aqueous formaldehyde solution, but may be a formaldehyde derivative such as paraformaldehyde. In this case, parts by weight (D) are converted to a 37% aqueous formaldehyde solution.

As the dispersant having a phenol ring, any dispersant having a phenol skeleton capable of reacting with formaldehyde can be used. In particular, ligninsulfonic acid which is a natural phenol polymer and synthetic phenol condensate are used. Bisphenols, aminobenzenesulfonic acid,
When a formaldehyde condensate or a bisphenols / amino acid / formaldehyde condensate is used, the reaction product with the copolymer exhibits good dispersibility and dispersion persistence. In addition, the said synthetic condensate is JP-B-6-60041, 6-07997.
It is a condensate described in JP-A No. 4 and other publications, and can be easily produced by the method described in Examples in the publication.

The reaction between the copolymer and the dispersant having a phenol ring is effective under weakly acidic to weakly alkaline conditions. In particular, when a monomer having an ester bond is used as the polyoxyalkylene monomer (B) having an unsaturated bond, p is used to suppress hydrolysis of the ester bond.
H8 or less is preferred. Further, since the molecular weight becomes extremely high under strong acidity, the pH is preferably 5 or more. Particularly preferred pH
Has a pH of 7 to 8. As the alkali for pH adjustment, NaOH, Ca (OH) _{2 and the} like are generally used.

It is preferable to mix an aqueous solution of the copolymer and an aqueous solution of a dispersant having a phenol ring, adjust the pH, and then continuously heat and add an aqueous formaldehyde solution. The reaction temperature is usually from 60 to 100 ° C.

The molecular weight of the reaction product obtained by the above method is preferably in the range of 10,000 to 30,000. If the molecular weight is lower than 10,000, the amount of low molecular weight products not exhibiting dispersibility is increased, and good dispersibility is not exhibited. Further, when the molecular weight is higher than 30,000, it shows cohesiveness and adversely affects dispersibility and the like.

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

The rate of addition of the dispersant to cement is usually 0.1 to 1.5% in terms of solids content. The dispersant of the present invention can be used in combination with other types of dispersants, thickeners and the like.

[0025]

According to the present invention, it is possible to provide a cement dispersant having very excellent dispersibility and excellent dispersion sustainability.

[0026]

EXAMPLES The present invention will be described in detail with reference to examples.

The used carboxylic acid having an unsaturated bond (A), the polyoxyalkylene monomer having an unsaturated bond (B), allylphenols (C), an aqueous formaldehyde solution (D: equivalent to a 37% aqueous solution), The dispersant (E) having a phenol ring is shown below (hereinafter referred to as a
To m).

Carboxylic acid having unsaturated bond (A) a: methacrylic acid b: acrylic acid c: maleic acid

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

Allylphenols (C) g: Allylphenol h: Allyl-substituted 3 and 3'-positions of 4,4'-dihydroxydiphenylmethane i: Allyl-substituted 3 and 3'-positions of 4,4'-dihydroxydiphenylsulfone

Formaldehyde aqueous solution (D) 37% formaldehyde aqueous solution

Dispersant (E) having a phenol ring j: Purified lignin sulfonic acid (Pearl Rex NL manufactured by Nippon Paper Industries Co., Ltd., solid content 30%) k: Bisphenol S / aminobenzenesulfonic acid / formaldehyde condensate (4- Using 50 parts of aminobenzenesulfonic acid, 45 parts of bisphenol S, 50 parts of a 37% aqueous formaldehyde solution, and 12 parts of 95% NaOH, a condensate aqueous solution was obtained according to the examples of JP-B-6-60041 and 6-39514. The solid content was adjusted to 20%.) L: Bisphenol A / glutamic acid / formaldehyde condensate (40 parts of bisphenol A, 30 parts of sodium L-glutamate, 37% aqueous formaldehyde solution 33)
And 14 parts of a 47% NaOH aqueous solution, and an aqueous solution of a condensate was obtained according to the examples of JP-B-6-079774 and JP-A-4-352751, and the solid content was adjusted to 20%. M: Bisphenol S / glutamic acid / formaldehyde condensate (50 parts of bisphenol S, 35 parts of sodium L-glutamate, 37% aqueous solution of formaldehyde 40)
And 20 parts of a 47% aqueous NaOH solution were used to obtain a condensate aqueous solution according to the examples of JP-B-6-079774 and JP-A-4-352751, and the solid content was adjusted to 20%. )

Copolymerization Example 1 150 parts of water was charged into a reaction vessel equipped with a stirring device, a reflux device, and a dropping device, and the temperature was raised to 90 ° C. afterwards,
2,4 parts by weight of diallyl-substituted 4,4'-dihydroxydiphenylsulfone (i), 34 parts of methacrylic acid (a), methoxypolyoxyethylene methacrylate (e) 64
And a mixed solution of 2.2 parts of water and 75 parts of water, a mixed solution of 2.2 parts of ammonium persulfate (polymerization initiator) and 175 parts of water were continuously added to the reaction vessel over 2 hours. The reaction was further performed at 90 ° C. for 1 hour to obtain an aqueous suspension of the copolymer. The active ingredient (A + B + C) in the suspension is 100 parts.

Copolymerization Examples 2 to 4 A carboxylic acid having an unsaturated bond (A), a polyoxyalkylene monomer having an unsaturated bond (B) shown in Table 1,
A copolymerization reaction was carried out in the same manner as in Polymerization Example 1 except that allylphenols (C) were used, to obtain copolymer aqueous suspensions of Copolymerization Examples 2 to 4. The active ingredient (A + B + C) in the suspension is 10
0 parts.

[0035]

[Table 1]

Example 1 The total amount of the aqueous suspension of the copolymer of Polymerization Example 1 [(A + B + C): 1]
00 parts] and a purified ligninsulfonic acid (j) aqueous solution 50
Then, the mixture was adjusted to pH 7.6 with a 47% aqueous NaOH solution. The mixture was heated to 90 ° C., 5 parts of 37% aqueous formaldehyde solution (D) was continuously added in 20 minutes, and the mixture was reacted at 90 ° C. for 20 hours to obtain a reaction product aqueous solution. The weight average molecular weight of the obtained reaction product measured using GPC is 16,000 (in terms of polyethylene glycol).

Examples 2 to 4 The same procedures as in Example 1 were carried out except that the total amount of the aqueous copolymer suspension in the copolymerization examples shown in Table 2, the dispersant having a phenol ring (E), and the aqueous formaldehyde solution (D) were used. Perform the same reaction,
The reactant aqueous solutions of Examples 2 to 4 were obtained.

The weight-average molecular weight (in terms of polyethylene glycol) of the obtained reaction product measured by GPC is shown in Table 3.
It was shown to.

[0039]

[Table 2]

[0040]

[Table 3]

Comparative Examples 1 to 4 In Examples 1 to 4, the aqueous suspension of the copolymer and the aqueous solution of the dispersant having a phenol ring were simply mixed without reacting.
Table 2 shows the relationship among A, B, C, and E.

Comparative Examples 5 and 6 Copolymers of Copolymerization Examples 1 and 2 alone.

Comparative Examples 7 and 8 Dispersants 1 and m having a phenol ring alone.

Comparative Example 9 Polymerization was carried out as follows in accordance with Reference Example 3 of JP-B-59-18338. 560.7 parts of water was charged into a reaction vessel equipped with a thermometer, a dropping funnel, a nitrogen gas inlet tube and a stirrer, and the inside of the reaction vessel was replaced with nitrogen under stirring and heated to 95 ° C. Next, methoxypolyoxyethylene methacrylate (NK ester M-230G, manufactured by Shin-Nakamura Chemical Co., Ltd., average number of moles of ethylene oxide added: 23) 7
A monomer mixture solution consisting of 5 parts, 25 parts of acrylic acid and 300 parts of water, and 34.5% aqueous solution of ammonium persulfate 34.5
Parts were added in 120 minutes, and 5 minutes after the addition was completed.
6.8 parts of a 10% aqueous solution of ammonium persulfate were added in 20 minutes. After completion of the addition, the temperature was maintained at 95 ° C. for 120 minutes to complete the polymerization reaction. Thereafter, neutralization was performed with a NaOH solution to obtain an aqueous solution of a copolymer.

[Concrete Test] Concrete tests were conducted for Examples 1 to 4 and Comparative Examples 1 to 9 with the compositions shown in Table 4.

Cement, fine aggregate, coarse aggregate, water, a dispersant, an AE agent, and an antifoaming agent were put into a forced kneading mixer having a kneading amount of 50 L, and kneaded for 90 seconds. The slump value of the concrete immediately after kneading was 18 cm. The addition ratio of the solid content of the dispersant (based on the amount of cement) was adjusted so as to be as follows. The amounts of the AE agent and the defoamer were adjusted so that the amount of air in the concrete became 4.5 ± 0.5% immediately after kneading. The slump value 90 minutes after the kneading was also measured. The measurement of slump value and air volume is based on JISA6
204.

The dispersibility was such that the slump value immediately after kneading was 18 cm.
And the dispersion sustainability is 9
The slump value after 0 minute (the degree of decrease from the slump value of 18 cm immediately after kneading) was evaluated. Table 5 shows the dispersibility and dispersion durability test results.

[0048]

[Table 4]

[0049]

[Table 5]

From Table 5, it can be seen that the reactants of Examples 1 to 4 are excellent in dispersibility since they have a lower addition ratio than the mere mixture of Comparative Examples 1 to 4.

From Examples 1 and 2 and Comparative Examples 5 and 6,
It can be seen that the reactants of the examples have the same dispersibility (addition rate) as the copolymer alone, and the dispersion persistence (slump value after 90 minutes) is good.

From Examples 3 and 4 and Comparative Examples 7 and 8,
It can be seen that the reactants of the examples have the same dispersion durability as the dispersant having a phenol ring alone and have excellent dispersibility.

According to the present invention, it is possible to provide a cement dispersant having excellent dispersibility and excellent dispersion sustainability.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location C04B 103: 40 (72) Inventor Shigeki Hikasa 2-8-1 Iidacho, Iwakuni-shi, Yamaguchi Prefecture Nippon Paper Stocks (72) Inventor Fumifumi Nakamoto 2-8-1 Iida-cho, Iwakuni-shi, Yamaguchi Prefecture Nippon Paper Chemicals Co., Ltd.

Claims (5)

[Claims] 1. A carboxylic acid (A) having an unsaturated bond,
A polyoxyalkylene monomer (B) having an unsaturated bond and an allylphenol (C) are copolymerized within the range (parts by weight) of the formula 1, and 20 ≦ A ≦ 35, 60 ≦ B ≦ 75, 1 ≦ C ≦ 10, A + B + C = 100 Formula 1 Further, an aqueous formaldehyde solution (D: equivalent to a 37% aqueous solution)
A cement dispersant containing a polymer compound as a main component obtained by reacting a dispersant having a phenol ring (E: corresponding to solid content) in the range (parts by weight) of Formulas 2 and 3 using C ≦ D ≦ 5C Equation 2 (A + B + C): E = 2: 8 to 9: 1 Equation 3 2. A dispersant (E) having a phenol ring,
The cement dispersant according to claim 1, which is any one of ligninsulfonic acid, bisphenols / aminobenzenesulfonic acid / formaldehyde condensate, and bisphenols / amino acid / formaldehyde condensate. 3. A carboxylic acid having an unsaturated bond (A)
Is (meth) acrylic acid and / or maleic acid. 4. The polyoxyalkylene monomer (B) having an unsaturated bond is (methoxy) polyoxyethylene methacrylate and / or (methoxy) polyoxyethylene allyl ether.
Item 7. The cement dispersant according to Item 1. 5. A carboxylic acid (A) having an unsaturated bond,
A polyoxyalkylene monomer (B) having an unsaturated bond and an allylphenol (C) are copolymerized within the range (parts by weight) of the formula 1, and 20 ≦ A ≦ 35, 60 ≦ B ≦ 75, 1 ≦ C ≦ 10, A + B + C = 100 Formula 1 Further, an aqueous formaldehyde solution (D: equivalent to a 37% aqueous solution)
A method for producing a cement dispersant containing a polymer compound as a main component obtained by reacting a dispersant having a phenol ring (E: corresponding to solid content) in the range (parts by weight) of Formulas 2 and 3 using C ≦ D ≦ 5C Equation 2 (A + B + C): E = 2: 8 to 9: 1 Equation 3