JP3375279B2 - Dispersant for cement - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a dispersant for cement. At work sites using cement compounds,
In order to improve work efficiency and save labor, and to shorten the construction period by early demolding the mold, give the cement mixture high fluidity and reduce the given fluidity over time (slump loss). It is required to suppress it and to develop a sufficient early strength in the early stage of curing. The present invention relates to a cement dispersant that meets such demands.

[0002]

2. Description of the Related Art Conventionally, as a dispersant for cement that imparts fluidity to a cement composition, a naphthalenesulfonic acid formalin high condensate salt, a melaminesulfonic acid formalin high condensate salt, a water-soluble vinyl copolymer, etc. have been used. There is. However, the cement mixture prepared by using the high-condensation product of naphthalenesulfonic acid formalin and the high-condensation product of melaminesulfonic acid formalin has a problem that the slump loss is large. In addition, conventionally proposed water-soluble vinyl copolymers (for example, JP-B-58-38380 and JP-A-2-1631).
08, Japanese Patent Publication No. 59-18338, Japanese Patent Publication No. 5-1105
The cement composition prepared by using No. 7, Japanese Patent Publication No. 5-36377) has a smaller slump loss than the case of using the naphthalene sulfonic acid formalin high condensate salt or the melamine sulfonic acid formalin high condensate salt, There is a problem that the delay property becomes large and the early strength is poorly expressed.
These problems are especially great in high strength cement formulations with low water / cement ratios.

[0003]

The problem to be solved by the present invention is that the conventional cement dispersants have a large slump loss or poor early strength development. This is a big point in a high-strength cement mixture with a suppressed cement ratio.

[0004]

However, the present inventors have
As a result of research to solve the above-mentioned problems, it was found that a water-soluble vinyl copolymer having a specific constitutional unit in a predetermined ratio is properly suitable as a dispersant for cement.

That is, in the present invention, 55 to 72 mol% of the structural unit A represented by the following formula 1 and 3 to 18 mol% of the structural unit B represented by the following formula 2 are contained in all the structural units. 3 to 15 mol% of the structural unit C represented by the formula 3, 3 to 12 mol% of the structural unit D represented by the following formula 4, and 1 to 12 mol% of the structural unit E represented by the following formula 5 (total) 100
Number average molecular weight of 5,000 to 450
No. 00 water-soluble vinyl copolymer.

[0006]

[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

[Formula 5]

In the formulas 1 to 5, R ¹ , R ² , R ³ : H
Or CH ₃ R ⁴ : an alkyl group having 1 to 3 carbon atoms X: a group M ^{1 represented} by the following formula 6 or formula 7: hydrogen, an alkali metal, an alkaline earth metal, ammonium or an organic amine n: 40 to 109 Integer m: integer from 5 to 25

[0008]

[Formula 6]

[Formula 7]

In formulas 6 and 7, M ² and M ^{3 are} : alkali metal, alkaline earth metal, ammonium or organic amine

The cement dispersant of the present invention has the formula 1 above.
A water-soluble vinyl copolymer having structural units A to E represented by formulas 5 to 5 in a predetermined ratio, and having a structure represented by the formula 4
Specific water-soluble vinyl copolymer having a relatively long polyoxyethylene graft chain derived from the structural unit D represented by the formula and a relatively short polyoxyethylene graft chain derived from the structural unit E represented by the formula 5 It consists of Structural unit A constituting such a water-soluble vinyl copolymer
To E are formed by copolymerizing the corresponding vinyl monomers.

The vinyl monomer forming the structural unit A represented by the formula 1 is 1) methacrylic acid, acrylic acid, 2) methacrylic acid alkali metal salt, alkaline earth metal salt, ammonium salt or There are organic amine salts, 3) alkali metal salts of acrylic acid, alkaline earth metal salts, ammonium salts or organic amine salts. Of these, alkali metal salts of methacrylic acid such as sodium and potassium are preferable.

The vinyl monomer forming the structural unit B represented by the formula 2 is 1) an alkali metal salt, an alkaline earth metal salt, an ammonium salt or an organic amine salt of methallyl sulfonic acid, and 2). There are alkali metal salts, alkaline earth metal salts, ammonium salts or organic amine salts of p-methallyloxybenzenesulfonic acid. Of these, alkali metal salts of methallyl sulfonic acid such as sodium and potassium are preferable.

The vinyl monomer forming the structural unit C represented by the formula 3 is methyl acrylate or methyl methacrylate.

The vinyl monomer forming the constitutional unit D represented by the formula 4 is an alkoxypolyethoxyethyl (meth) having 1 to 3 carbon atoms in which the number of repeating oxyethylene units is 40 to 109. There is acrylate.
This includes, for example, methoxypolyethoxyethyl (meth)
Examples thereof include acrylate, ethoxypolyethoxyethyl (meth) acrylate, n-propoxypolyethoxyethyl (meth) acrylate, and isopropoxypolyethoxyethyl (meth) acrylate. Among them, the number of repeating oxyethylene units is 55 to 100. Certain methoxypolyethoxyethylmethacrylates are preferred.

As the vinyl monomer which forms the structural unit E represented by the formula 5, there is methoxypolyethoxyethyl methacrylate in which the number of repeating oxyethylene units is 5 to 25. Of these, methoxypolyethoxyethyl methacrylate having a repeating number of oxyethylene units of 7 to 23 is preferable.

The water-soluble vinyl copolymer of the present invention has a predetermined copolymerization ratio of the above-mentioned vinyl monomers which will form the structural units A to E in the presence of the radical initiator. It is obtained by radical copolymerization. Radical copolymerization is performed by aqueous solution polymerization using water or a mixed solvent of water and a water-soluble organic solvent. More specifically,
First, each vinyl monomer is dissolved in water to prepare an aqueous solution containing each vinyl monomer in a total amount of 10 to 45% by weight. Next, in a nitrogen gas atmosphere, a radical initiator is added to the aqueous solution, and a radical copolymerization reaction is performed at 50 to 70 ° C. for 5 to 8 hours to obtain a water-soluble vinyl copolymer.
The type of radical initiator used is not particularly limited as long as it decomposes at the copolymerization reaction temperature and generates radicals, but a water-soluble radical initiator is preferably used. Examples of such water-soluble radical initiators include persulfates such as potassium persulfate and ammonium persulfate, hydrogen peroxide, and 2,2-azobis (2-amidinopropane) dihydrochloride. These can also be used as a redox initiator in combination with a reducing substance such as sulfite or L-ascorbic acid, as well as an amine.

The water-soluble vinyl copolymer of the present invention thus obtained contains the structural unit A in an amount of 55 to 7 in all the structural units.
2 mol%, 3 to 18 mol% of the structural unit B, 3 to 15 mol% of the structural unit C, 3 to 12 mol% of the structural unit D, and 1 to 12 mol% of the structural unit E (total of 100 mol%). We shall have in proportion. The number average molecular weight is 5,000 to 4
The range is 5000 (GPC method, pullulan conversion, the same applies hereinafter).

The cement dispersant of the present invention comprises the specific water-soluble vinyl copolymer described above,
When preparing a cement mixture using this, other agents can be used in combination depending on the purpose. Such agents include air entraining agents, antifoaming agents, waterproofing agents, curing accelerators, preservatives and the like. The method of use thereof includes a method of adding it together with water for kneading at the time of preparation of the cement mixture, a method of adding it to the cement mixture after kneading, and the like.

The cement dispersant of the present invention can be used in cement formulations such as mortar and concrete prepared with a binder made of cement or a combination of cement and a fine powder admixture. As the cement, various portland cements such as ordinary cement, early-strength cement, and medium-heat portland cement, and various mixed cements such as blast furnace cement, fly ash cement, and silica fume cement can be used. Slag fine powder, fly ash, etc. are mentioned. The use amount of the dispersant for cement of the present invention is usually 0.05 to 2.0 parts by weight in terms of solid content with respect to 100 parts by weight of a binder composed of cement or cement and a fine powder admixture. But
The ratio is preferably 0.1 to 1.5 parts by weight.

The water-soluble vinyl copolymer used as the dispersant for cement of the present invention is a comb-type graft copolymer having a polyoxyethylene graft chain as a side chain in the molecule and has a relatively long poly-ethylene chain in the molecule. The feature is that the oxyethylene graft chain and the relatively short polyoxyethylene graft chain are shared at a predetermined ratio. The cement dispersant of the present invention comprising a water-soluble vinyl copolymer having such characteristics has a water / cement ratio of 2 as well as a normal cement mixture having a water / cement ratio of more than 40%.
The effect is high even for 0 to 40% of a cement composition, for example, concrete. Water / cement ratio of 20-
Even for high-strength concrete whose content has been suppressed to 40%, high fluidity is imparted, slump loss is small, and retardation of setting is suppressed to exhibit sufficient early strength.

[0021]

Embodiments of the present invention include the following 1) to 6). 1) 62 mol% of the structural unit A formed of sodium methacrylate, 12 mol% of the structural unit B formed of sodium methallyl sulfonate, and C of the structural unit C formed of methyl acrylate in all structural units. 12 mol%, methoxypolyethoxyethyl (the number of repeating oxyethylene units is 68, hereinafter referred to as v = 68) Methacrylate unit D formed from 8 mol% and methoxypolyethoxyethyl (v = 9) methacrylate A dispersant for cement comprising a water-soluble vinyl copolymer having a number average molecular weight of 14800 and having a structural unit E of 6 mol% (total 100 mol%).

2) 57 mol% of the structural unit A formed of sodium methacrylate and 15% of the structural unit B formed of sodium methallylsulfonate in all the structural units.
Molar%, a structural unit C formed from methyl acrylate
14 mol%, methoxypolyethoxyethyl (v = 6
8) A number average molecular weight of 11,000 having 10 mol% of the structural unit D formed of methacrylate and 2 mol% (total 100 mol%) of the structural unit E formed of methoxypolyethoxyethyl (v = 23) methacrylate.
A dispersant for cement consisting of the water-soluble vinyl copolymer.

3) In all the constituent units, constituent unit A formed of sodium methacrylate is 72 mol%, constituent unit B formed of sodium methallylsulfonate is 8 mol%, and methyl acrylate is constituted. 5 mol% of the unit C, 4 mol% of the structural unit D formed from methoxypolyethoxyethyl (v = 95) methacrylate, and 11 mol% of the structural unit E formed of methoxypolyethoxyethyl (v = 9) methacrylate. A dispersant for cement, comprising a water-soluble vinyl copolymer having a number average molecular weight of 18,500 in a proportion of (total 100 mol%).

4) 65 mol% of the structural unit A formed of sodium methacrylate, 5 mol% of the structural unit B formed of sodium methallylsulfonate, and methyl acrylate in all structural units. 10 mol% of unit C, methoxypolyethoxyethyl (v = 45)
12 mol% of the structural unit D formed from methacrylate
And 8 mol% of the structural unit E formed from methoxypolyethoxyethyl (v = 23) methacrylate (total 10
A dispersant for cement comprising a water-soluble vinyl copolymer having a number average molecular weight of 37,000 and having a proportion of 0 mol%).

5) 70 mol% of the structural unit A formed of sodium acrylate, 10 mol% of the structural unit B formed of sodium p-methallyloxybenzenesulfonate, and methyl acrylate in all structural units. 6 mol% of the structural unit C formed, 11 mol% of the structural unit D formed of isopropoxypolyethoxyethyl (v = 55) acrylate, and a structural unit formed of methoxypolyethoxyethyl (v = 9) methacrylate A dispersant for cement, comprising a water-soluble vinyl copolymer having a number average molecular weight of 23000 and having E in an amount of 3 mol% (total 100 mol%).

6) 58 mol% of the structural unit A formed of methacrylic acid, 18 mol% of the structural unit B formed of sodium p-methallyloxybenzenesulfonate, and methyl acrylate in all structural units. Constituent unit C is 8 mol%, methoxypolyethoxyethyl (v
= 68) 1 is a structural unit D formed from methacrylate
0 mol% and methoxypolyethoxyethyl (v = 23)
6 mol% of the structural unit E formed from methacrylate
Number average molecular weight of 85 in total (100 mol%)
A dispersant for cement consisting of a water-soluble vinyl copolymer of No. 00.

Examples are given below to make the constitution and effects of the present invention more specific, but the present invention is not limited to the examples. In the following Examples and the like, unless otherwise indicated, parts mean parts by weight, and% means% by weight excluding the amount of air.

[0028]

Examples Test Category 1 (Synthesis of Water-Soluble Vinyl Copolymer) Example 1 107 parts (1.24 mol) of methacrylic acid, 38 parts (0.24 mol) of sodium methallylsulfonate, 21 parts of methyl acrylate ( 0.24 mol), methoxy polyethoxyethyl (v = 68) methacrylate 495 parts (0.1
6 mol), 60 parts (0.12 mol) of methoxypolyethoxyethyl (v = 9) methacrylate and 800 parts of water were charged into a reaction vessel, and a 30% aqueous solution of sodium hydroxide 16
After 5 parts were added to neutralize and uniformly dissolved, the atmosphere was replaced with nitrogen. Keep the temperature of the reaction system at 60 ° C in a warm water bath,
55 parts of a 20% aqueous solution of sodium persulfate was added to start the polymerization, and the polymerization reaction was continued for 6 hours to complete the polymerization.
Then, 6 parts of a 30% aqueous sodium hydroxide solution was added to neutralize the acidic decomposed product to obtain a product. A part of the obtained product was concentrated by an evaporator, precipitated and purified in a mixed solvent of acetone / isopropanol, and then dried to obtain a water-soluble vinyl copolymer (Example 1). When this water-soluble vinyl copolymer was analyzed by NMR measurement, elemental analysis, titration analysis, gel permeation chromatography (GPC) measurement, etc., structural units formed from sodium methacrylate / meta Structural unit formed from sodium rilsulfonate / Structural unit formed from methyl acrylate / Structural unit formed from methoxypolyethoxyethyl (v = 68) methacrylate /
Structural unit formed from methoxypolyethoxyethyl (v = 9) methacrylate = 62/12/12/8/6
It was a water-soluble vinyl copolymer having a number average molecular weight of 14,800 at a ratio of (mol%, total 100 mol%).

Examples 2 to 6 and Comparative Examples 1 to 10 Water soluble vinyl copolymers of Examples 2 to 6 and Comparative Examples 1 to 10 were obtained in the same manner as the water soluble vinyl copolymer of Example 1. . Table 1 shows the contents of the water-soluble vinyl copolymers of Examples and Table 2 shows the contents of the water-soluble vinyl copolymers of Comparative Examples.

[0030]

[Table 1]

[0031]

[Table 2]

In Tables 1 and 2, am-1: sodium methacrylate am-2: sodium acrylate am-3: methacrylic acid bm-1: sodium methallyl sulfonate bm-2: p-methallyloxybenzenesulfone. Sodium acid cm-1: Methyl acrylate dm-1: Methoxypolyethoxyethyl (v = 68) methacrylate dm-2: Methoxypolyethoxyethyl (v = 95) methacrylate dm-3: Methoxypolyethoxyethyl (v = 45) methacrylate dm-4: isopropoxypolyethoxyethyl (v = 5
5) Acrylate em-1: Methoxypolyethoxyethyl (v = 9) methacrylate em-2: Methoxypolyethoxyethyl (v = 23) methacrylate rm-1: Methoxypolyethoxyethyl (v = 35) methacrylate rm-2: Methoxy Polyethoxyethyl (v = 150)
Methacrylate rm-3: sodium styrenesulfonate rm-4: 2-hydroxyethyl methacrylate

Test Category 2 (Preparation and Evaluation of Concrete) Concrete Preparation Under the mixing conditions shown in Table 3, the concrete of each example was prepared as follows. In a 50-liter pan-type forced kneading mixer, ordinary Portland cement (specific gravity = 3.16, Blaine value 3300), fine aggregate (Oi River water-based sand, specific gravity = 2.6)
3) and coarse aggregate (crushed stone from Okazaki, specific gravity = 2.66) were sequentially added and kneaded for 15 seconds. Then, in each of the test examples, the water-soluble vinyl copolymer prepared in Test Category 1 was used in the range of 0.1 to 1.5% by weight in terms of solid content with respect to the cement so that the target slump falls within the range of 21 ± 1 cm. And kneading with water and kneading for 2 minutes. At this time, in each of the test examples, an air amount adjusting agent was added so that the target air amount was 4.0 to 5.0%.

[0034]

[Table 3]

Evaluation of Concrete The concrete of each prepared test example was evaluated as follows. The results are summarized in Tables 4 to 7. Slump: Immediately after kneading, after standing for 60 minutes and after standing for 90 minutes, measurement was performed according to JIS-A1101. Slump residual rate: (Slump after 90 minutes / Slump immediately after) × 100 Air amount: Measured according to JIS-A1128. Setting time: Measured according to JIS-A6204. Compressive strength: Measured according to JIS-A1108.

[0036]

[Table 4]

[0037]

[Table 5]

[0038]

[Table 6]

[0039]

[Table 7]

In Tables 4 to 7, * 1: the addition amount of the dispersant for cement is shown in terms of solid content based on 100 parts of cement * 2: high-condensate formalin naphthalene sulfonate * 3: not cured I could not measure because

[0041]

The above-described dispersant for cement of the present invention has the effect of imparting high fluidity to the cement mixture while suppressing slump loss, and at the same time imparting high early strength.

Continuation of front page (56) Reference JP-A-9-71447 (JP, A) JP-A-9-286645 (JP, A) JP-A-7-247150 (JP, A) JP-A-9-286646 (JP , A) JP-A-9-40446 (JP, A) JP-A-8-12396 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C04B 24/26

Claims (2)

(57) [Claims] 1. A structural unit A represented by the following formula 1 in an amount of 55 to 72 mol%, a structural unit B represented by the following formula 2 in an amount of 3 to 18 mol%, and 3 to 15 mol% of the structural unit C shown, 3 to 12 mol% of the structural unit D of the following formula 4, and 1 to 12 mol% of the structural unit E of the following formula 5 (total 100 mol% (2) A water-soluble vinyl copolymer having a number average molecular weight of 5,000 to 45,000 in a ratio of 1). [Formula 1] [Formula 2] [Formula 3] [Formula 4] [Formula 5] (In the formulas 1 to 5, R ¹ , R ² , R ³ : H or CH ₃ R ⁴ : an alkyl group having 1 to 3 carbon atoms X: a group M ^{1 represented} by the following formula 6 or formula 7, hydrogen: Alkali metal, alkaline earth metal, ammonium or organic amine n: integer of 40 to 109 m: integer of 5 to 25) [Formula 6] [Formula 7] (In Formula 6 and Formula 7, M ² , M ³ : alkali metal, alkaline earth metal, ammonium or organic amine) 2. A cement dispersant according to claim 1 SL placing water / cement ratio is applied to 20-40% of the concrete.