JP2669761B2 - Powdery cement dispersant and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a powdery cement dispersant and a method for producing the same. The industrial application field of the present invention is wide-ranging, such as concrete with excellent workability and low slump loss. The concrete in the present invention is a general term for cement paste, mortar, and concrete.

[0002]

2. Description of the Related Art Conventionally, polycarboxylic acid copolymers have been used as cements, aggregates,
It is known that it can be used for improving workability of concrete by mixing it with water and water, and that it can be used for concrete with excellent durability because it can control the water reduction effect of concrete and the amount of air. Guidelines (formulation, production and construction guidelines for high-performance AE water reducing agent concrete)
The same commentary p27-34, 116-118, 165-168, 1992, 6,20 Published by Architectural Institute of Japan.

However, polycarboxylic acid copolymers are usually prepared by using a liquid high-performance water reducing agent as an aqueous solution.
Since there was not be premixed with hydraulic material such as cement.

[0004] Therefore, when concrete is kneaded at the construction site, the fluidity differs depending on the material used,
There was a problem that the work became complicated, such as the need to weigh on site.

Under these circumstances, the materials used, such as a mixture of a powdery water reducing agent and a hydraulic material and a mixture of fine aggregates, are preliminarily mixed to stabilize the quality and improve the kneading operation. What was simple was desired.

As a result of various studies to solve the above-mentioned problems of the prior art, the present inventor introduced a polycarboxylic acid type copolymer and an inorganic powder into a spray dryer and spray-dried them. The inventors have found that a powdery cement dispersant that can be redispersed in water can be obtained, and have completed the present invention.

[0007]

A resolution means for] That is, the present invention is a powdery cement dispersant comprising a liquid <br/> polycarboxylic acid copolymer and an inorganic powder, a liquid polycarboxylic acid-based copolymer This is a method for producing a powdery cement dispersant, comprising introducing a polymer and an inorganic powder into a spray drying device and spray drying.

Hereinafter, the present invention will be described in detail.

The polycarboxylic acid copolymer according to the present invention is in a liquid state, and is composed of acrylic acid, methacrylic acid, crotonic acid, maleic anhydride, maleic acid, maleic acid monoester, tetrahydrophthalic anhydride, and tetrahydrophthalic acid. One or more monomers selected from the group consisting of and monomers copolymerizable therewith, for example, methyl polyethylene glycol methacrylate, methyl polyethylene glycol maleate, hydroxypropyl methacrylate, hydroxyethyl acrylate, and alkyl propane Copolymers with sulfonic acids and the like can be mentioned.

As specific examples, methacrylic acid-methyl methacrylate polyethylene glycol copolymer, styrene-methyl polyethylene glycol glycol maleate, methacrylic acid-hydroxypropyl methacrylate copolymer, acrylic acid-hydroxy acrylate Ethyl copolymer, methyl polyethylene glycol allyl ether-maleic acid copolymer and the like can be mentioned.

The molecular weight of these copolymers is 3,000
Although it is not particularly limited as long as it is ~ 200,000, 10
It is preferably at most 000, more preferably from 50,000 to 80,000. When the molecular weight of the copolymer is less than 3,000, the air entrainment becomes large and the delay becomes large, and when it exceeds 200,000,
The dispersing power of the powdery dispersant tends to be weak.

When powdering these copolymers, it is preferable to spray-dry the aqueous solution. In this case, two or more polycarboxylic acid-based copolymers are used in combination. By using a combination of one or more polycarboxylic acid copolymers and lignin sulfonic acid, melamine sulfonic acid, or naphthalene sulfonic acid,
It can be made into powder.

Examples of the inorganic powder according to the present invention include one or more selected from the group consisting of cementitious substances, latent hydraulic substances such as blast furnace slag and fly ash, and ultrafine powder.

As the cementitious substance, various portland cements such as normal, early strength, and ultra-early strength, various mixed cements obtained by mixing these portland cements with blast furnace slag, silica, or fly ash, white cement, ultra-rapid cement, In addition, alumina cement or the like can be used.

Here, as the ordinary Portland cement, "ordinary Portland cement" made by Andes cement, etc., and as the ultra-rapid hardening cement, the product name "Jet Cement" by Onoda Cement Co., Ltd. and the product name "Denka Super" by Denki Kagaku Kogyo Co., Ltd. Cement "and the like, and examples of the alumina cement include Denka Alumina Cement No. 1 and Denka Alumina Cement No. 2 manufactured by Denki Kagaku Kogyo Co., Ltd.

In the present invention, as the cementitious substance, low heat-generating cement such as moderate heat cement or sulfate-resistant cement can be used.

Although the particle size of the cementitious substance is usually 5 to 30 μm, smaller or larger ones having hydraulic properties can of course be used.

In the present invention, it is also possible to use a cementitious substance together with a rapid hardening material, an expanding material, a high-strength admixture and various other cement admixtures used in ordinary cement concrete. Is.

As rapid hardening materials, Denka Atomic and Denka Cosmic manufactured by Denki Kagaku Kogyo KK, and as expanding materials, Denka CSA # 20 manufactured by Denki Kagaku Kogyo KK
As a high-strength admixture, Denka Co., Ltd.'s trade name "Denka II-1000" is used. As other cement admixtures, Daiichi Cement Co., Ltd.'s trade name "Fine Cellament" is used.
And the like.

The particle size of these cement admixtures is usually 0.5
-30 μm, but smaller or larger than this is of course usable.

The ultrafine powder used in the present invention is inorganic and is a particle which is smaller by one order, preferably two orders, than the cementitious substance.

There are no particular restrictions on the components of the ultrafine powder, but those which are readily soluble in water are not suitable. The method for producing the ultrafine powder is not particularly limited and may be a usual method. However, from the viewpoint of economy, it is preferable to use one produced by pulverization and classification or one produced as a by-product.

Specifically, pulverized materials such as blast furnace slag and fly ash, silicon, silicon-containing alloy,
Silica dust and silica fume, which are by-products during the production of zirconia and the like, are preferred.

In addition, calcium carbonate, silica gel, opalaceous silica, titanium oxide, aluminum oxide, zirconium oxide, various glasses, clay minerals such as bentonite and its calcined products, amorphous aluminosilicate, chromium oxide,
It is also possible to use fine powder such as activated carbon.

The amount of the inorganic powder used is not particularly limited, but 10 to 100 parts by weight is suitable, and 20 to 80 parts by weight, based on 100 parts by weight of the solid content of the polycarboxylic acid copolymer. Parts by weight, more preferably 30 to 50 parts by weight. If the amount of the inorganic powder used is less than 10 parts by weight, it becomes difficult to collect powder, especially the redispersible powdery cement dispersant obtained by spray drying, and the powder state becomes sticky and difficult to handle. If the amount exceeds 100 parts by weight, the ratio of the copolymer to the inorganic powder is reversed and the amount used as the dispersant increases, which is not economically preferable.

The present invention is to pulverize the above-mentioned polycarboxylic acid copolymer and inorganic powder.

When powdering the polycarboxylic acid type copolymer and the inorganic powder, it is preferable to introduce both into a spray drying device, and particularly to spray dry an aqueous solution of the polycarboxylic acid type copolymer. In particular, when the polycarboxylic acid copolymer is spray-dried alone or separately from the inorganic powder, the polycarboxylic acid-based copolymer adheres to the inner surface of the spray-drying tower or the polycarboxylic acid-based copolymers cause blocking. It is more preferable to simultaneously introduce the aqueous solution of the polycarboxylic acid-based copolymer and the inorganic powder into the spray drying apparatus from the viewpoint of ease.

The spray drying apparatus is not particularly limited as long as the polycarboxylic acid copolymer and the inorganic powder can be sprayed stably, and an ordinary spray drying apparatus can be used.

The method of spray drying is not particularly limited, but the polycarboxylic acid copolymer and the inorganic powder are simultaneously sprayed into the drying apparatus, but the introduction paths are separately separated. Three-fluid nozzle method or two-fluid nozzle method, or a method in which a mixed slurry composed of an inorganic powder and a polycarboxylic acid-based copolymer is prepared in advance, and the slurry is sprayed to a drying device with a two-fluid nozzle or a rotating disk. Is preferably adopted.

As drying conditions, the inlet temperature of the spray dryer is preferably about 100 to 150 ° C., and if the amount of water evaporation is large,
Although a larger amount is preferable, drying conditions of a usual spray dryer can be used.

[0031]

The present invention will be described in more detail with reference to the following examples.

Example 1 As a spray dryer, a trade name "West Germany Nubirosa Spray Dryer" manufactured by Nippon Dairy Machinery Co., Ltd. was used, and the composition as shown in Table 1 was maintained while maintaining the hot air temperature at the dryer inlet at 130 ° C. From the central tube of the three-fluid nozzle, an inorganic powder obtained by diluting an aqueous solution of a polycarboxylic acid-based copolymer at a rate of 2.0 to 5.0 kg / h from the central tube of the three-fluid nozzle and 20% by weight with water from the outer tube. The slurry of A was discharged at the rate of 0.5 to 2.5 kg / h and the compressed air was also discharged from the outermost tube at the rate of 2.0 to 3.0 kg / h at the same time, and blocking and recovery were measured to observe the powder state. . The results are also shown in Table 1.

<Material used> Polycarboxylic acid copolymer: aqueous solution of methacrylic acid-methyl methacrylate polyethylene glycol copolymer, manufactured by Sanyo Chemical Co., Ltd. Inorganic powder A: blast furnace slag, average particle size by gas adsorption method 1.
0μ

[0034]

[Table 1]

As is clear from the table, the powder state of the cement dispersant obtained by the method of the present invention was good.

[0036]

According to the method of the present invention, a polycarboxylic acid copolymer can be easily formed into a powder, and a redispersible cement dispersant having excellent dispersibility can be obtained. In addition, the redispersible cement dispersant produced by the method of the present invention can be stored for a long period of time, and when this is used as a cement admixture, fluidity can be ensured and workability is improved, and the water / cement ratio It becomes possible to obtain a low-strength, high-strength cement hardened body with excellent durability.

Claims (2)

(57) [Claims] 1. A liquid polycarboxylic acid-based copolymer , comprising
One selected from mineral substances, latent hydraulic substances and ultrafine powder
A powdery cement dispersant comprising one or more inorganic powders. 2. A liquid polycarboxylic acid-based copolymer ,
One selected from mineral substances, latent hydraulic substances and ultrafine powder
The method for producing a powdery cement dispersant according to claim 1, wherein the seed or two or more kinds of inorganic powders are introduced into a spray dryer and spray-dried.