JPH0153222B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel cement dispersant, and more particularly to a cement dispersant containing a co-condensation resin of a urea compound or thiourea compound into which a carboxyl group has been introduced and an aldehyde, or a derivative thereof as an active ingredient. Cement dispersants are used in large quantities in almost all concrete fields, including civil engineering and construction concrete and secondary product concrete, for the purpose of improving workability and improving the strength and durability of hardened concrete. Cement dispersant is usually 10-30% in mixing water
Since it completely disperses the flocs of cement particles that are agglomerated at a ratio of , down to the primary particles, when the amount of water is the same, it acts as a so-called fluidizing agent that increases the softness of concrete and improves its fluidity. In addition, when obtaining concrete with the same workability, it acts as a so-called water reducing agent, which can reduce the unit water amount by about 10% compared to the case without additives, and by about 20% in the case of high performance. . Normally, the strength of hardened concrete is inversely proportional to the unit amount of water, and the smaller the amount of water, the stronger the concrete. Therefore, using a good cement dispersant will give you high strength and durability without impairing workability. It is possible to obtain excellent concrete. Cement dispersants currently in use can be roughly divided into those whose main component is lignin sulfonate or its derivatives, those whose main component is sulfonate of higher polyhydric alcohols, those whose main component is oxyorganic acid, and those whose main component is oxyorganic acid. There are those whose main component is allyl sulfonate, those whose main component is polyoxyethylene alkyl ether, and those whose main component is polyol complex (Chemical admixtures for concrete, p. 14, edited by the Japan Society of Materials Science, Asakura Shoten). High performance products include those whose main component is a salt of a formalin high condensate of a sulfonated naphthalene or alkylnaphthalene, and those whose main component is a salt of a sulfonated product of a melamine-formalin condensate. However, these known cement dispersants are not always satisfactory in use. For example, lignin sulfonate has drawbacks such as being easily spoiled in summer or easily forming sediment during storage. Gluconic acid, which is currently commonly used among oxyorganic acids, has a setting retarding property, so the amount added is limited depending on the purpose of use. Although polyol composites have the effect of increasing strength, their water reduction performance is insufficient. High performance dispersants and have disadvantages such as being less effective when added in small amounts and being expensive. Recently, a method has been proposed for obtaining a high-performance, inexpensive cement dispersant using urea instead of melamine (Japanese Patent Application Laid-Open No. 126031/1983). However, this effect is still small when added in a very small amount, and it is necessary to add a considerable amount in order to reduce the desired amount of water. Therefore, the present inventors carried out intensive studies to improve this drawback of the conventional technology, and found that by modifying a co-condensate of urea or thiourea and aldehyde with a carboxylic acid group-imparting agent, a cement with excellent dispersion performance could be obtained even when a small amount was added. It was discovered that a dispersant can be obtained, and the present invention was completed. Thus, according to the present invention, there is provided a cement dispersant containing as an active ingredient a water-soluble resin selected from modified amino resins and derivatives thereof, in which carboxylic acid groups are introduced into a co-condensed resin of a urea compound or a thiourea compound and an aldehyde. Ru. The water-soluble resin used in the present invention is synthesized as follows. First, the urea or thiourea used as the first component may be any one commonly used as a raw material for urea resins or thiourea resins, and specific examples include urea,
Examples include thiourea, which may be used in the form of a mixture of two or more, if necessary. Among them, urea is preferred because of its price and ease of availability. Further, the aldehyde used as the second component may be any aldehyde as long as it is uniformly dissolved within the reaction system, and specific examples thereof include formaldehyde, acetaldehyde, propionaldehyde, and the like.
Among these, formaldehyde is preferred;
It is usually used in the form of its aqueous solution, ie formalin. Further, as a third component, a carboxylic acid group imparting agent is used to introduce a carboxylic acid group into the resin. Such a carboxylic acid group-imparting agent is capable of introducing a carboxyl group or an acid anhydride group into the product by reacting with a functional group, that is, a methylol group or an amino group, present in the cocondensation resin with urea or thiourea. Specific examples include amino acids such as glycine, alanine, leucine, aspartic acid, lysine, arginine, and phenylalanine; half-amides of dicarboxylic acids such as maleic acid, succinic acid, and phthalic acid; and cyanoacetic acid. , carboxylic acid compounds having a condensable active hydrogen such as malonic acid; formyl group-containing carboxylic acids such as glyoxylic acid, formylacetic acid, formylpropionic acid, and formylbutyric acid; ketocarboxylic acids such as pyruvic acid and 2-ketoglutaric acid. It will be done. These carboxylic acid group-imparting agents may have at least a part of the carboxyl group or acid anhydride group forming a salt, and specific examples thereof include:
Examples include metal salts such as sodium salts and potassium salts, ammonium salts, and amine salts. These salts do not necessarily have to be prepared in advance, and even if they are synthesized in the co-condensation reaction system by coexisting an acidic carboxylic acid group-giving agent and a basic substance. good. Further, the degree of neutralization of the carboxylic acid group can be appropriately selected within a range such that the resulting co-condensed resin is water-soluble. Furthermore, if necessary, a part of the carboxylic acid group can be esterified or amidated. An aqueous solution of the water-soluble modified resin is prepared by cocondensing these components in the presence of water or by neutralizing the cocondensation with a base. At this time, the order of charging each component is not particularly limited, and any method may be employed as long as a water-soluble co-condensed resin can be obtained in the end. As a specific example, for example, after adding the second component to the first component and converting it into methylol, the third component is added to form a methylol group or amino group and an amino group or formyl group in the third component. Examples include a method in which the components are condensed with a functional group, and a method in which each component is charged at the same time to perform co-condensation of the three components at once. The ratio of each component to be used is selected as appropriate, but usually the amino group in the first component is 0.5 to 2 moles, and the condensable functional group in the third component is 0.1 mole or more per mole of the second component. Preferably, the amount is in a range of 0.2 mol or more, and in particular, the acid value of the co-condensed resin produced (when using a carboxylic acid group imparting agent in the form of a salt, the acid value when it is considered as an acid) is 30 It is desirable to set the range to the above. The reaction of each of these components is usually carried out in the presence of water.
1 minute to 3 minutes at a temperature of 100℃, preferably 20 to 90℃
Conducted over time. Since this reaction proceeds quickly and quantitatively, it is extremely advantageous compared to sulfonation reactions and the like. During the reaction, a base such as sodium hydroxide, potassium hydroxide, ammonia, methylamine, ethylamine, diethylamine, triethylamine, etc. can be present, and in this case, an aqueous solution containing the salt of the co-condensed resin is directly prepared. Further, when a cocondensation resin is synthesized from each component without the presence of these basic substances, neutralization is performed by adding a basic substance afterwards, if necessary. In this case, the amount of the basic substance added is appropriately selected within a range that can make the product water-soluble. In addition, within the range that does not essentially impair the effects of the present invention, melamines, phenols, ketones,
Compounds that can be cocondensed with urea or thiourea and aldehydes, such as amines, can be cocondensed, and sulfonation can be simultaneously performed with acidic sulfites or metasulfites such as alkali metals, ammonia, and organic amines. You can also do that. In this way, an aqueous solution of a water-soluble modified resin selected from a co-condensation resin of a urea compound or a thiourea compound and an aldehyde or a derivative thereof modified with a carboxylic acid group-giving agent is prepared. The water-soluble resin used in the present invention usually has a number average molecular weight of 200 or more, preferably 500 or more, and is added to cement in solid form or in the form of an aqueous solution of a desired concentration. The amount added to cement is usually 0.03 to 2.0 parts by weight, preferably 0.05 to 1.0 parts by weight of modified resin per 100 parts by weight of cement.
Parts by weight range. The cement dispersant of the present invention is used as a fluidizing agent or a water reducing agent depending on the purpose. In the field of cement fluidizers, it has almost the same performance as the naphthalene sulfonic acid-formaldehyde high condensate system, which is prized for its high strength properties, and the existing sulfonic acid-modified melamine-formaldehyde condensate system. It has the advantage of being able to achieve the desired effect with a small amount of addition compared to . Also, in the field of water reducing agents for cement, it has far superior performance compared to the lignin sulfonic acid type, which is generally used. Further, it can be used in combination with other cement dispersants, and other additives such as setting accelerators and setting retarders can also be used in combination, if necessary. The present invention will be explained in more detail with reference to Examples below. Note that all parts and percentages in the examples are based on weight. Reference Example 1 A sodium hydroxide aqueous solution was added to a mixture of 100 parts of urea and 338 parts of a 37% formalin aqueous solution to adjust the pH to 9, and the mixture was stirred at 90°C for 30 minutes. Next, sulfuric acid was added to adjust the pH to 3.0, and after stirring at 90°C for 4 hours, 62.5 parts of glycine was added, followed by stirring at 90°C for 1 hour. Next, add sodium hydroxide aqueous solution and adjust the pH to 9.
And so. In this way, a colorless and transparent sodium salt aqueous solution of the urea-glycine-formaldehyde cocondensate was obtained.
The viscosity of a 25% aqueous solution of this substance at 25℃ is 6 cps
It was hot. Reference Example 2 Thiourea-
An aqueous sodium salt solution of a glycine-formaldehyde condensate was obtained. The viscosity of a 25% aqueous solution of this product at 25°C was 7 cps. Reference example 3 60 parts (1 mol) of urea and 37% formalin aqueous solution
Aqueous sodium hydroxide solution was added to a mixture of 162 parts (2 moles) to adjust the pH to 10, and the mixture was stirred at 90°C for 30 minutes. Then, after adding sulfuric acid and adjusting the pH to 3.0,
After stirring at 90℃ for 3 hours, 40% glyoxylic acid 139
(0.75 mol), and after adjusting the pH to 3 by adding an aqueous sodium hydroxide solution, the mixture was further stirred at 90°C for 3 hours. Thereafter, an aqueous sodium hydroxide solution was added to adjust the pH to 10, and the condensation was completed. In this way, a colorless and transparent sodium salt aqueous solution of the carboxylic acid group-introduced urea-formaldehyde condensate was obtained. The viscosity of a 25% aqueous solution of this substance at 25℃ is
It was hot at 7cps. Reference Example 4 Ammonia water was added to a mixture of 100 parts of urea and 405 parts of 37% formalin to adjust the pH to 9, followed by stirring at 80°C for 1 hour. Then, after adding sulfuric acid to make the pH 3.5,
After stirring at 90℃ for 3 hours, 62.5 parts of glycine was added.
Stirred at 90°C for 1 hour. Next, ammonia water was added to adjust the pH to 8.5. Thus urea-glycine-
An aqueous ammonium salt solution of formalin cocondensate was obtained. The viscosity of a 25% aqueous solution of this substance at 25℃ is 7 cps
It was hot. Example 1 The modified resin aqueous solutions obtained in Reference Examples 1 to 4 were evaluated for their performance as cement water reducing agents. During the experiment, the slump, air volume, and compressive strength of concrete tests were determined according to JIS A-1101 and JIS-
In accordance with A1116 and JIS-A1108, the cement is ordinary Portland cement, the fine aggregate is river sand (maximum particle size 2.5mm, FM2.74), and the coarse aggregate is river gravel (maximum particle size 25mm, FM7.03). was used.
In order to clarify its performance as a water reducing agent,
Conditions were set so that the slump was approximately constant by keeping the concrete mix the same and adjusting the amount of modified resin added. The results are shown in Table 1.

[Table] *1 Solid content From the above results, the dispersant of the present invention exhibits excellent dispersibility with a very small amount added compared to commercially available water reducing agents, and also has superior long-term strength despite the same amount of water. It is understandable that the growth rate is high. From this, it can be understood that it is widely used as an excellent water reducing agent for ready-mixed concrete and secondary products. Example 2 The performance of the modified resin aqueous solutions obtained in Reference Examples 1 and 3 as a dispersant for mortar was measured.
The results are shown in Table 2. The mixture is 500 parts of ordinary Portland cement, 1000 parts of Toyoura standard sand, 250 parts of modified resin aqueous solution, and JIS
-Evaluation as a dispersant was performed according to the flow test method of R5201. The modified resin aqueous solution was used after adjusting the concentration so that the amount (solid content) of the modified resin added to the cement was a predetermined ratio.

【table】

[Table] From the results, it can be seen that the modified resin aqueous solution of the present invention has performance equivalent to or better than commercially available products that have been used in the past.

Claims (1)

[Claims] 1. A cement dispersant containing as an active ingredient a water-soluble resin selected from modified amino resins and derivatives thereof, in which a carboxylic acid group is introduced into a co-condensed resin of a urea compound or a thiourea compound and an aldehyde.