JPH0151460B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an admixture for cement compositions, and in particular, it combines excellent water-reducing properties with excellent cement dispersion action and high mechanical strength of cured products without substantially adversely affecting the desirable properties of the cement composition. Concerning a unique water reducing agent for cement-based materials. More specifically, the present invention uses as an active ingredient a melamine/dicyandiamide/aldehyde sulfonic acid group-containing non-urea modified condensate having a reaction molar ratio (M):(D) of melamine and dicyandiamide of 1:03 to 3. The present invention relates to an admixture for cement compositions, characterized in that it contains an admixture for cement compositions. The fact that melamine/formaldehyde condensation products having sulfonic acid groups and melamine/urea/aldehyde-based modified condensation products containing sulfonic acid groups are useful alone as water reducing agents for mortar and cements has been reported, for example, in Japanese Patent Publication No. 43 (1973). -No. 21659, Special Publication 1977
-13991 and Japanese Patent Publication No. 55-43419. In addition, it has been reported that the condensation product can be applied as a water reducing agent to cement/gypsum molded bodies and lightweight concrete, and is effective in improving the workability and strength of concrete. It is described in JP-A-51-144424. Japanese Patent Publication Publication No. 1973 (1973) proposed that the undesirable drawbacks such as decreased workability, decreased viscosity, and decreased strength were improved by adding a melamine/aldehyde condensation product containing a sulfonic acid group in combination with other admixtures.
−16455, Special Publication No. 52-8850, Special Publication No. 53-28330
No., Special Publication No. 54-27852, Japanese Patent Publication No. 53-145841,
JP-A No. 52-66529 is known. In addition, to improve workability, methods that have characteristics in fluidity and addition timing are disclosed in Japanese Patent Publication No. 54-22460 and Japanese Patent Application Laid-Open No. 50-1999.
29637, and there is also a proposal to use the condensate as powder, pellets and coated pellets in order to improve the working life of concrete, as disclosed in JP-A-54-139929. However, water-soluble salts of sulfonated melamine resins have lower water-reducing properties per added amount compared to general water-reducing agents, and in order to obtain the same water-reducing properties,
It is necessary to add it in a larger amount than general water reducing agents, and its performance as a water reducing agent is still unsatisfactory. Furthermore,
The above proposals do not disclose any melamine/dicyandiamide/aldehyde sulfonic acid group-containing non-urea modified condensate and its use in cement materials. The present inventors have conducted repeated research with the aim of obtaining a water reducing agent composition having even higher cement dispersibility. As a result, by blending melamine/dicyandiamide/aldehyde sulfonic acid group-containing non-urea modified condensates into cements, which had never been proposed before, the dispersibility of cement was dramatically improved. With the addition of less water than before, it is now possible to mix concrete and mortar sufficiently, resulting in significant improvements in workability, and especially in concrete products, not only mechanical strength but also significant initial strength improvements are achieved. It has been discovered that this admixture for cement compositions exhibits unique performance as an excellent water reducing agent and high strength imparting agent for concrete and mortar materials. Accordingly, it is an object of the present invention to provide a new type of admixture for cementitious compositions. The above objects and many other objects and advantages of the present invention will become more apparent from the following description. The melamine/dicyandiamide/aldehyde sulfonic acid group-containing non-urea modified condensate of the present invention is
Melamine (M): dicyandiamide (D) = 1:0.3~
It can be obtained by reacting melamine, dicyandiamide, an aldehyde and a sulfonating agent in an aqueous solvent in a reaction molar ratio of 3. If dicyandiamide is too small in the reaction molar ratio of melamine and dicyandiamide, even if it is used as a water reducing agent for mortar, the effect of increasing workability will be low and the water reducing effect per amount added will be small, resulting in lower initial strength. No improvement can be expected, and in order to obtain the same water-reducing properties, a large amount must be added, which is inconvenient. Further, if the amount of dicyandiamide is too excessive, exceeding 3 moles, the stability of the aqueous solution of the modified condensate of the present invention is poor and a precipitate is formed when left standing, which is also not preferred. Therefore, the reaction molar ratio of melamine (M):dicyandiamide (D) is 1:0.3 to 3 as described above.
A molar amount is adopted, but 1:05 to 2 moles is more preferable. The amount of aldehyde used to form the melamine/dicyandiamide/aldehyde sulfonic acid group-containing non-urea modified condensate of the present invention can be appropriately selected within a wide range, but the total number of moles of melamine and dicyandiamide (M+D) The number of moles of aldehyde (F) is (M+D):(F)=1: about 1 to about 6
The ratio is preferably 1: about 2 to about 5.
I can give an example of the usage amount. Approximately 1 aldehyde per mole of melamine and dicyandiamide
If the amount is less than 6 moles, the resulting condensate will be water-insoluble, and if it exceeds about 6 moles, not only will unreacted formaldehyde increase, but water reducing properties will also tend to decrease. It is better to adopt it. The aldehyde used is
Usually, an aqueous formaldehyde solution is used, but
Formaldehyde polymers such as paraformaldehyde and trioxymethylene can also be used. In addition, acetaldehyde, glyoxal, etc. can also be used if desired. The sulfonating agent used in the sulfonic acid group-containing non-urea modified condensate of the present invention can be appropriately selected in a wide range of amounts. Reaction molar ratio (M+D) (in terms of SO ₃ ):
(SO ₃ )=1: about 0.8 to 1.6 is preferably used.
More preferably, the ratio is about 1:1.0 to 1.5. If the amount is too small, less than about 0.8 mol, the resulting condensate tends to become water-insoluble, making it impossible to use it stably as a cement water-reducing agent, and also not being able to expect a water-reducing effect. In addition, if the amount exceeds about 1.6 mol, crystalline precipitates are likely to be formed due to the excess sulfonating agent, and the water-reducing effect tends to decrease. It is better to adopt As the sulfonating agent,
Water-soluble salts of sulfite and alkali metals are usually preferably used, and preferred examples include sodium metabisulfite, potassium metabisulfite, sodium hydrogensulfite, and potassium hydrogensulfite. If desired, ammonium hydrogen sulfite, Rongarit, etc. can also be employed. The melamine/dicyandiamide/aldehyde sulfonic acid group-containing non-urea modified condensate of the present invention can be produced by reacting melamine, dicyandiamide, aldehyde, and a sulfonating agent in an aqueous solvent. According to one embodiment, melamine, dicyandiamide, and aldehyde are reacted in advance in an aqueous solvent to produce a melamine/dicyandiamide/aldehyde condensate, and then a sulfonating agent is added to carry out the sulfonation reaction. You can get what you want. According to this embodiment, for example, melamine, dicyandiamide, and aldehyde are mixed in an aqueous solvent,
Under weakly acidic or slightly alkaline conditions, preferably PH
Under conditions of about 6 to about 9 degrees Celsius, for example about 50 degrees Celsius to about 50 degrees Celsius
A melamine/dicyandiamide/aldehyde condensate can be obtained by reacting at a temperature of about 100°C. This condensate is usually obtained in the form of a mixture of various degrees or degrees of methylolation and/or condensation, and these degrees or degrees are determined by PH conditions, reaction temperature, It can be changed as appropriate by selecting reaction conditions such as reaction time. In the above embodiment, for example, depending on the degree of methylolation or the degree of condensation, an aqueous solution (for example, a concentration of about 20 to about 60% by weight) of the condensate can form a condensate that does not become substantially water-insoluble. , it is preferable to select the above reaction conditions. A sulfonating agent is added to the melamine/dicyandiamide/aldehyde condensate thus obtained, and the reaction is carried out at a temperature of about 50°C to about 100°C, for example, under conditions of a pH of about 9 to about 12. After drying, it is further heated under neutral to acidic conditions, preferably at a pH of about 3 to about 7, for example about 40° to about 7.
The object of the present invention can be obtained by causing a condensation reaction at a temperature of about 100°C. Furthermore, according to another aspect, the melamine/dicyandiamide/aldehyde sulfonic acid group-containing non-urea modified condensate of the present invention is obtained by preparing all raw materials of melamine, dicyandiamide, aldehyde, and sulfonating agent in an aqueous solvent. It can also be produced by reacting with According to this embodiment, for example, melamine, dicyandiamide, an aldehyde, and a sulfonating agent are mixed in an aqueous medium under neutral to strongly alkaline conditions, preferably with a pH of about 7 to about
After reacting under conditions of about 12° C., for example, at a temperature of about 50° C. to about 100° C., the reaction is further carried out under neutral to acidic conditions, preferably at a pH of about 3 to about 7.
For example, the object of the present invention can be obtained by carrying out a condensation reaction at a temperature of about 40°C to about 100°C. Even in the case of this embodiment, the target product is usually obtained in the form of a mixture with various degrees or degrees of methylolation and/or condensation, and these degrees or degrees are different from the PH
It can be changed as appropriate by selecting reaction conditions such as reaction temperature, reaction time, etc. Melamine/dicyandiamide/ of the present invention thus obtained
An aqueous solution of a non-urea modified condensate containing an aldehyde sulfonic acid group has a concentration (as solid content) of, for example, approximately
It is best to choose between 20 and 60% by weight. For example, the melamine/dicyandiamide/aldehyde sulfonic acid group-containing non-urea modified condensate of the present invention, which can be produced by the method exemplified above, can be used alone as a water reducing agent for cement and mortar materials; It can demonstrate unique performance as an agent that imparts excellent fluidity and high mechanical strength to cement and mortar materials. Furthermore, the sulfonic acid group-containing non-urea modified condensate can also provide excellent effects when used in combination with known water reducing agents. The admixtures according to the invention can be utilized in amounts ranging, for example, from about 0.1 to about 10% by weight, preferably from about 0.2 to about 5% by weight, based on cement.
If the amount is less than the above-mentioned amount, sufficient water-reducing performance cannot be achieved, and if the amount is added in excess of the above-mentioned amount, the mechanical strength of the cement composition will deteriorate, and it is also economically undesirable. . The processing effects according to the above embodiment will be explained below with reference to figures. In FIG. 1, the horizontal axis shows the amount of water added to the cement/sand material (% by weight relative to cement), and the vertical axis shows the flow torque (g·cm) during cement kneading. The test method is as follows. Ordinary Portland cement (manufactured by Tokuyama Cement) was used as the test cement, and standard sand from Toyoura was used as the aggregate. Fluidity test: Cement: standard sand in a weight ratio of 1:1
water and a water reducing agent (% by weight relative to the cement weight) are added and kneaded to prepare a mortar sample. The flow resistance of the kneaded sample mortar is measured using a torque meter by rotating a paddle-shaped stirring blade equipped with a rotating torque meter at a speed of 10 rpm/min. The larger the value, the greater the kneading resistance. When the flow torque of mortar was measured by changing the amount of water added using the above method, the results shown in FIG. 1 were obtained. Here, the curve of Comparative Example 1 is a plain test of a mortar blend without adding a water reducing agent. In addition, the curve of Example 3 is the same as that of Example 3 as a water reducing agent in mortar.
This is a flow torque curve when 1% by weight (in terms of solid content) of the condensation product is added to cement.
Compared to Comparative Example 1 of the plain test, it can be seen that the effect of addition as a water reducing agent is remarkable, and the workability of the non-hardening mortar is greatly improved. Examples 5 to 9 are also shown in FIG. Although there are some differences, it can be seen that the water reduction effects including Example 3 are almost the same. Moreover, Comparative Example 3 is a commercially available sulfonated melamine resin water reducing agent. In FIG. 1, each curve has a substantially horizontal relationship with the amount of added water on the horizontal axis. Therefore, by comparing the amount of added water at a certain constant flow torque value with the plain value (Comparative Example 1), the degree of water reduction property can be determined. That is, the water reduction rate (%) of the illustrated water reducing agent can be determined from FIG. 1 by the following formula. Water reduction rate (%) = W ₁ - W ₂ / W ₁ × 100 However, W ₁ : Amount of water added at constant torque of plane (g) W ₂ : Amount of water added at constant torque of water reducing agent addition (g) Melamine of the present invention /dicyandiamide/aldehyde sulfonic acid group-containing non-urea modified condensates Examples 3, 5, 6, 7, 8, and 9 had water reduction rates of 22.6%, 22.1%, 19.6%, 20.7%, respectively.
22.0% and 19.2%. Furthermore, the commercially available water reducing agent of Comparative Example 3 resulted in a water reduction rate of 17.3%. It can be seen that the sulfonic acid group-containing non-urea modified condensate of the present invention has surprisingly excellent water reducing performance compared to commercially available sulfonated melamine resin water reducing agents. In FIG. 2, the horizontal axis shows the amount of water reducing agent added (% by weight per cement), and the vertical axis shows the water reduction rate (%). When the melamine/dicyandiamide/aldehyde sulfonic acid group-containing non-urea modified condensate of the present invention is added in different amounts and mixed into mortar and kneaded, the water reduction rate (%) is plotted as shown in Figure 2. Examples 1-4). Comparing this result with Comparative Example 3 and examples in which the amount added was increased or decreased, it is obvious that the water reduction performance is dramatically improved, but what is surprising is that it is possible to achieve a high water reduction rate, especially when a small amount is added. As described above using several examples with reference to the accompanying drawings, the active ingredient melamine/dicyandiamide/aldehyde sulfonic acid group-containing non-urea modified condensate in the present invention has a high degree of It can be seen that it has water-reducing performance, and in particular, it can exhibit a water-reducing effect even when added in a small amount. Hereinafter, several embodiments of the water reducing agent of the present invention will be further explained with reference to Examples. Percentages and parts are by weight unless otherwise specified. The test method is as follows. Solid content (%): Accurately weigh approximately 1 g of the reaction product aqueous solution in a weighing bottle, dry in a hot air dryer at 105±1° C. for 3 hours, and then calculate from the weight change. Solution state: Visually observe the state of the reaction product aqueous solution after pH adjustment. Viscosity (cp): Measure the reaction product aqueous solution at room temperature using a B-type viscometer. Water reduction rate (%): Mix cement: standard sand at a ratio of 1:1, add water reducing agent and water, knead, and measure the flow torque (g cm). Calculated from the difference in water volume from the plain test (without water reducing agent), which shows the same flow torque value. Compressive strength (Kg/cm ² ): Measured by the method shown in JIS R 5201. The experimental conditions are as follows. Cement: Portland cement (manufactured by Tokuyama Cement) Sand: Standard sand from Toyoura Mixing ratio: Cement/water/sand = 600/330/1200
(Parts by weight) Water-cement ratio (W/C): 0.55 The admixture was added as an aqueous solution in the amount shown in Table 1 (solid weight ratio to cement). Flow test (seconds): Using a P funnel, the flow time (seconds) at 20°C was measured. The experimental conditions are as follows. Cement: Portland cement (manufactured by Tokuyama Cement) Sand: Standard sand from Toyoura Mixing ratio: cement/water/sand = 1/0.5/1 Examples 1 to 4 Two three-diameter glass flasks equipped with a stirrer, thermometer, and condenser 30% formalin
500 parts, 126 parts of melamine and dicyandiamide
Add 84 parts of 7.5N caustic soda and 0.5 volume part of 7.5N caustic soda, then maintain the internal temperature at 70°C and carry out the reaction for 0.5 hour with stirring to obtain a colorless and transparent aqueous solution of the reaction product. After that, cool to 50℃ and add sodium pyrosulfite.
Add 190 parts and water so that the solid content is 25%, raise the internal temperature again, maintain it at 70°C, and conduct the reaction for 3 hours while stirring. Then cool to 50℃ and 30%
The pH was adjusted to 5.0 with sulfuric acid, and the condensation reaction was carried out at 50°C for 5 hours. After that, cool it down and adjust the pH to 8.0.
A melamine/dicyandiamide/aldehyde sulfonic acid group-containing non-urea modified condensate of the present invention having a solid content of 26.6% and a viscosity of 26 centipoise was obtained. The obtained product was added to mortar in the amount shown in Table 1 (in terms of solid content), and the water reduction rate, flow value, and compressive strength were measured. The performance is shown in Table 1.
It can be seen that the water reducing agent composition of the present invention has an excellent water reducing effect and strength enhancing effect even when added in a smaller amount. Example 5 30% formalin was added to the same reaction apparatus as in Example 1.
Add 500 parts of melamine, 126 parts of dicyandiamide, 190 parts of sodium pyrosulfite, and 20 parts by volume of 7.5N caustic soda, maintain the internal temperature at 70°C,
React for 1 hour while stirring. After that, cool to 50℃ and add water to make the solid content 30%.
% sulfuric acid to adjust the pH to 3.9 and react for 3 hours.
Thereafter, it was cooled to room temperature and the pH was adjusted to 8.5 to obtain a transparent modified condensate containing a sulfonic acid group of the present invention having a solid content of 28.6% and a viscosity of 27 centipoise. The obtained product was added to cement in the amount shown in Table 1, and tested in the same manner as in Example 1. The performance is shown in Table 1. Examples 6 to 7 The method of Example 1 except that the reaction raw materials in Example 1 were changed to the types and amounts listed in Table 1, the sulfonation reaction was carried out at a solid content of 40%, and the condensation reaction was carried out at 80°C for 3 hours. The reaction was carried out in the same manner as above to obtain an aqueous solution of the reaction product. The properties of the resulting aqueous solution and the performance of the product as a water reducing agent are shown in Table 1. Examples 8 to 9 In Example 1, the reaction raw materials were used in the types and amounts listed in Table 1, the solid content was adjusted to 40%, and the sulfonation reaction and condensation reaction were carried out at 80°C for 5 hours at a solid content of 25%. The reaction was carried out in the same manner as in Example 1,
An aqueous reaction product solution was obtained. The properties of the resulting aqueous solution and the performance of the product as a water reducing agent are shown in Table 1. Comparative Example 1 A cement mortar was prepared without adding any admixtures, and flow tests and compressive strength tests were conducted. However, the results showed that the fluidity was low and the mechanical strength was also low. The performance is shown in Table 1. Comparative Example 2 A reaction was carried out in the same manner as in Example 1, except that the types and amounts of the reaction raw materials were changed to those listed in Table 2, to obtain a reaction aqueous solution. The properties of the obtained aqueous solution and the performance of the product as a water reducing agent are shown in Table 2.
It was shown to. Compared to the examples of the present invention, this material has a lower water reduction rate per amount added to cement mortar and does not improve fluidity. Further, mechanical strength was not improved either. Note that Examples 8 and 3 have been added to Table 2 for convenience of comparison. Comparative Example 3 Except for using a commercially available water-soluble salt of sulfonated melamine resin in cement mortar as a water-reducing agent,
A test similar to Example 1 was conducted. The test results are in Table 2
It was shown to.

【table】

【table】

[Table] As is clear from the results in Tables 1 and 2 above, the melamine/dicyandiamide/aldehyde sulfonic acid group-containing modified condensate of the present invention has significantly improved cement mortar fluidity as a cement water reducing agent. shows high fluidity especially when added in small amounts, and
The cured product has the performance of high mechanical strength.

[Brief explanation of drawings]

The accompanying drawings, FIGS. 1 and 2, are graphs showing the relationship between the amount of added water and the flow torque, and the amount of water reducing agent added and the water reduction rate for examples of the present invention and several comparative examples.

Claims (1)

[Claims] 1 Contains as an active ingredient a melamine/dicyandiamide/aldehyde sulfonic acid group-containing non-urea modified condensate having a reaction molar ratio (M):(D) of melamine and dicyandiamide of 1:0.3 to 3. An admixture for cement compositions characterized by: 2. The reaction molar ratio (M+D) of the total number of moles of melamine and dicyandiamide (M+D) to the number of moles of the sulfonating agent (in terms of _SO3 ): ( _SO3 ) = 1:0.8 to 1.6, according to claim 1 admixture for cement compositions. 3. The cemetone composition according to claim 1, wherein the reaction molar ratio (M+D) of the total number of moles of melamine and dicyandiamide (M+D) and the number of moles of aldehyde (F): (F) = 1:1 to 6. Admixture for use.