KR100754693B1 - Improvements of Dispersants Properties Using Oxidation - Google Patents

Abstract

The present invention relates to a method for improving physical properties of a dispersant. Specific methods improve performance by oxidizing existing dispersants applied to concrete water reducing agents, air entrainers and fluidizing agents, dispersants such as coal slurries and gypsum slurries, fluidizing agents for the manufacture of bricks and sidewalk blocks, diluents and dye dispersants in groundwater development, etc. In particular, it is a method designed to produce a dispersant with improved new physical properties, such as air entrainment effect, improved fluidity and reduction over time when applied to concrete.

Dispersant, fluidizing agent, diluent, dye dispersant, oxidation reaction for concrete

Description

Properties Improvement of Dispersants Using Oxidation {Improvements of Dispersants Properties Using Oxidation}

1 is a diagram showing the shear stress and the apparent viscosity according to the increase and decrease of the shear rate of the dispersant prepared according to the present invention.

2 is a comparative result of measuring the dispersibility of the NSFP dispersant prepared in Preparation Example 3 according to the present invention and the conventional NSF-based dispersant by ultraviolet spectroscopy.

3 is a comparative result of measuring the dispersibility of PSP, which is a dispersant of Preparation Example 2 prepared according to the present invention, and a conventional PS-based dispersant by ultraviolet spectroscopy.

4 is a comparative result of measuring the dispersibility of the LSP and the conventional LS-based dispersant prepared in Preparation Example 1 according to the present invention by ultraviolet spectroscopy.

The present invention relates to a method for improving physical properties of a dispersant. The specific method is an air entraining effect by oxidizing existing dispersants used in concrete water reducing agents, air entrainers and fluidizing agents, dispersing agents such as coal slurries and gypsum slurry, fluidizing agents for brick and sidewalk blocks, diluents and dye dispersants in groundwater development, etc. In addition, the present invention relates to improving physical properties of existing dispersants by preparing dispersants with improved new physical properties such as improved fluidity and reduced changes over time.

Dispersant for concrete is used to improve the quality and workability of concrete. It is an important material in concrete after cement, water and aggregate. These concrete dispersants are chemically belonging to surfactants, and if they have excellent foaming action according to the foaming, dispersing, wetting, etc. surfactant properties, they are air emollients, foaming, dispersing and wetting. It is used as a high performance AE sensitizer if it has an excellent wetting action and a high performance sensitizer and a high performance sensitizer.

The air entrainer is an admixture that is essential for winter seasons because it improves the workability of concrete by the ball bearing effect of fine bubbles in the solid state without entraining the air bubbles and increases the resistance to freeze-thawing after solidification. Air entrainers are mainly wood resin salts, synthetic detergents, sulfonated lignin salts, petroleum salts, fatty acids and resin acids and salts thereof, organic salts of sulfonated hydrocarbons, and the like.

Reducing agents for general concrete construction are the most commonly used sensitizers based on lignin sulfonates (LS, Ligno Sulfonates), and when the amount is excessive, the amount of air such as hexavalent or pentose is present in the sensitizer. Ideally increasing or significantly delaying the hydration of cement requires careful use or handling.

On the other hand, high performance sensitizers that outperform ordinary sensitizers such as lignin disperse on the surface of cement particles, disperse the particles more strongly by electrostatic or steric repulsion, and lower the overall viscosity significantly, thus dispersing the cement and aggregate particles with a relatively small amount of water. It is a concrete admixture that makes it possible. High performance sensitizer increases the resistance to freeze-thaw when only air entrainer is used, but bubbles in the concrete may act as defects, thereby degrading the strength of the concrete. It is a admixture for the purpose of increasing the strength by the reducing effect. Representative high performance sensitizers include Melamine Sulfonated Formaline Condensates (MSF) and Naphthalene Sulfonated Formaline Condensates (NSF) developed in the 1960s in Germany and Japan. In recent years, petroleum sulfonate (PS) using similar petroleum by-products or wastes, which are similar in performance, has been researched and released at home and abroad (Korean Patent 181010, Russian Patent, 97102303, US Patent 5,112,363, 5,100,438, 5,082,469, 5,100,438, British Patent 2,230,207A, 2,099,451A, International Patent 92/0351, US Patent 5,186,846). This has been an essential admixture for producing high-strength concrete with less air entrainment and delayed cement hydration even when the excess water is used.

However, when the high performance water-reducing agent is used, the workability is drastically reduced due to the slump loss phenomenon in which the slump of concrete decreases rapidly as time passes during mixing and transporting the concrete in the ready mixed concrete plant. This causes difficulties such as clogging of pumps used for concrete pouring and excessive energy consumption. This phenomenon is absorbed by the naphthalene-based or melamine-based high performance sensitizer on the surface of the cement particles, and the effect of dispersing the cement particles by the electrostatic repulsion of the adsorption layer is thinned by the large amount of electrolyte generated by the hydration of the cement or the adsorption layer. This is because they are buried in cement hydration and lost (Industrial Chemistry and Technology, Vol. 12, No. 5, 199423-31).

Therefore, since the late 1985, researches on the development of next-generation high performance water reducing agents with little change of concrete fluidity over time, water loss effect, and slight air entrainment have been actively conducted in Japan, etc. As a result, polycarboxylic acid (PC, Polycarboxylates) And carboxylic acid systems such as oxycarboxylic acids (OC, OxyCarboxylates) are invented and commercially available.

Since these products contain a large amount of carboxyl groups capable of hydrogen bonding in the molecule, they are ideal for high performance water reducing agents because they have a high water loss rate and a small change in concrete fluidity with time, that is, a small change over time. However, since it is several times more expensive than the conventionally used water reducing agents such as LS and NSF, there is a difficulty in the practical general purpose. However, due to frequent earthquakes and collapses, demand for high performance concrete AE water reducers is expanding rapidly in Korea as well as in developed countries.

In summary, dispersants mainly used as general water reducing agent, high performance water reducing agent and high performance AE water reducing agent for concrete are currently LS type, NSF type and polycarboxylic acid (PC) type and PS type. I have a problem. In other words, the LS system is inexpensive, but limited in usage due to excessive air volume and condensation delay, and the NSF system is relatively expensive and has a large change in concrete fluidity over time, and the PC system has very high physical properties but is very expensive.

Recently, in order to solve this problem, additives having various properties such as coagulation accelerators and coagulation delay agents may be added, or reactive polymers having functional groups such as esters, acid chlorides, acid amides, and acid anhydrides may be added to the existing dispersants. In order to improve the physical properties by adding (UK Patent 2,164,930A, Korean Journal of Concrete, Vol. 7, No. 5, 1995, p. 189-199, Korean Institute of Industrial Chemistry, Vol. 9, No. 3, 1998, p. 336-341). However, there are many problems such as the reaction is very complicated, the expected physical properties are not expected, and the cost of the device is high, which is not a fundamental solution.

In addition, gelling in an alkaline atmosphere provides high water retention and at the same time, α, β-monoethylenically unsaturated carboxylic acid is used as a polymer compound in order to solve problems such as form collapse and dry out during demolding. A method of producing a cement composition comprising an emulsion copolymer comprising an essential monomer (Japanese Patent Laid-Open No. 3-131553) and an aqueous mixture of a vinyl polymer emulsion and a water-soluble vinyl copolymer in a region having a liquidity of pH 9 or more. And a method of simultaneously providing high fluidity and material separability to a cement formulation prepared using a high performance water reducing agent, which is composed of an aqueous mixture having a viscosity more than twice (Japanese Patent Laid-Open No. 9-71447). . In addition, a method for producing a high flow concrete additive containing a copolymer emulsion having a glass carboxyl group obtained from a monomer component in a polymer chain in order to produce a high flow concrete having excellent fluidity filling property and excellent separation resistance (Japanese Patent Laid-Open No. 8-225353 Ho). Although the above methods can be said to be an effective method for producing a high flow concrete dispersant, there is a disadvantage in that the price of the monomer used is expensive.

The present invention oxidizes relatively inexpensive dispersants such as LS-based, NSF-based, and PS-based to produce carboxyl and hydroxy groups capable of hydrogen bonding in the existing dispersant molecules. It is intended to significantly improve the performance of the dispersant. In addition, by oxidatively decomposing sugar present in the LS system and causing condensation delay of the concrete mixture, it is possible to induce high quality as a high performance water reducing agent so that there is no restriction in the amount of use thereof.

Fenton's reagent, a mixture of hydrogen peroxide and iron salt as an oxidizing agent, has been studied in recent years, and its use has been actively studied in various industrial wastewater treatment fields. Fenton's reagents can also be used to convert biologically degradable materials into biodegradable materials, to reduce the toxicity of wastewater that contains toxic compounds and thus adversely affect microorganisms, and to treat untreated materials by microorganisms. The trend is diversifying (Chemosphere, Vol. 39, No. 12, 1999, p. 1997-2006, Journal of the Korean Society for Environmental Engineering, Vol. 13, No. 2 1991, p. 123-132, Journal of Korean Society for Environmental Engineering, Vol. 25, No. 1 2003, p. 87-93 ). In addition, a method of using an initiator for graft copolymerization of an acrylic monomer and a ligno sulfonic acid of a mixture of hydrogen peroxide and iron salt (US Pat. No. 4,891,415) is also known.

The reaction mechanism of such a fenton reagent with an organic substance can be expressed as follows.

^{_{Fe 2+ + H 2 O 2 →}} Fe 3+ + OH - + · OH ... … … … … … … … … … … (One)

OH + RH → R · + H 2 O ... … … … … … … … … … … (2)

R + + OH → ROH... … … … … … … … … … … (3)

R · + H ₂ O ₂ → ROH +. … … … … … … … … … … (4)

ROH + 1 / 2O ₂ → ROOH. … … … … … … … … … … (5)

Disclosure of Invention It is an object of the present invention to provide a concrete dispersant capable of improving the dispersibility of a concrete mixture by using a conventional dispersant in consideration of the above conventional problems of the dispersant, and a method of manufacturing the same.

It is another object of the present invention to provide a dispersing agent having a new physical property such as improving the airflow effect and air entraining stability while improving the fluidity and preventing the deterioration of fluidity over time while increasing the water-resistance rate compared to the existing dispersant. It is.

The present invention is a lignin sulfonate (LS, Ligno Sulfonates), petroleum sulfonic acid (PS, Petroleum Sulfonates), naphthalene sulfonate formaldehyde condensate (NSF, Naphthalene Sulfonation Formalin Condensates) and poly to achieve the above object Conventional concrete dispersants, which are roughly classified as carboxylic acids (PC, Polycarboxylates), were used. As oxidants, Fenton reagent, H ₂ O ₂ , KMnO ₄ , K ₂ Cr ₂ O ₇ , O ₃ , and K ₂ S ₂ O ₈ In addition, the present invention is characterized by improving the physical properties of the existing dispersant using a Fenton reagent.

The oxidation reaction of representative organic compounds using Fenton reagent is expected as follows.

H ₂ O ₂ + RH → ROH + H ₂ O... … … … … … … … … … … (6)

ROH + 1 / 2O ₂ → ROOH. … … … … … … … … … … (7)

Representative theories explaining the dispersibility of unconsolidated concrete according to the amount of added concrete dispersant are DLVO (Derjagunin Landau Verway Overbe) theory, which achieves dispersion stability by electrical repulsive force between particles, dispersant structure, adsorption type and thickness of adsorption layer. The three-dimensional effect theory explains that the dispersion stability of particles is maintained by the three-dimensional repulsive force.

That is, NSF-based and melamine-based dispersants are adsorbed on the surface of cement particles in the form of rods, and the cement particles are dispersed by the strong electrostatic repulsion force indicated by the negative ions of sulfonic acid groups bonded in the chemical structure. However, the polycarboxylic acid-based dispersant has a synergistic effect of the electrostatic repulsion by the negative (-) ions of the carboxyl groups bonded in the chemical structure and the steric effect by the main chain or side chains to obtain the effect of the cement particles dispersed.

In the present invention, by oxidizing the existing dispersant using a Fenton reagent to form a carboxyl group and a hydroxyl group in the structure of the existing dispersant, the electrostatic repulsion by the negative (-) ions of the carboxyl group and the hydrogen bond, main chain or side chain of the hydroxy group It is a theoretical feature that the steric effect by synergistically acts to obtain the effect of improving the dispersibility of the cement particles.

Hereinafter, the present invention will be described in detail through production examples and examples.

Preparation Example 1.

Taking the oxidation treatment process of LS-based admixture as an example, the properties improvement process of existing concrete admixtures is described first. And 1 g of ferrous sulfate (FeSO ₄ ) were mixed and stirred for 30 minutes, and then 5 ml of hydrogen peroxide (15%) was slowly added dropwise and stirred for 30 minutes. After slowly heating to 70 ℃ and maintained at 70 ℃ for 2 hours to completely react the unreacted product to obtain a final product (LSP).

Preparation Example 2.

Performed as in Preparation Example 1, the starting material was carried out for the PS system, not the LS system (PSP).

Preparation Example 3.

Performed as in Preparation Example 1, the starting material was carried out for the NSF system, not LS (NSFP).

The above method is not limited to LS series, PS series and NSF series, but is similar to other conventional dispersants having anionic surfactants.

Example 1 Rheological Properties of Cement Paste

After the reception of the dispersant sample prepared in Preparation Example 1-3 above at water / cement = 0.35, the shear stress and the apparent viscosity according to the increase and decrease of the shear rate were measured after 60 minutes, and thus the characteristics of the cement paste's aging characteristics in terms of rheological properties were measured. In order to observe, the test results are shown in FIG. 1 using a Rheolab UM, MC 20 (Physica) cylindrical viscometer and Z3 DIN (bob radius 12.5 mm, cup radius 13.56 mm, maximum shear stress 1441 Pa).

From the results shown in FIG. 1, the dispersing system to which the dispersing agent prepared in Preparation Examples 1-3 had a lower shear stress value than the dispersing system using the LS, PS, and NSF dispersing agents of the standard showed fluidity loss compared to the conventional dispersing agents. This is greatly suppressed to show a stable flow state, and it can be seen that the remarkable slump loss is alleviated compared with the existing dispersion system.

Example 2 Concrete Preparation and Property Comparison

In order to confirm the effect on the slump, air amount and strength of the concrete dispersant samples prepared in Preparation Example 1-3, the performance test was performed by adding them to concrete, and the test results are shown in Table 1.

The material and concrete mix used for the test is 370kg of Hanil Cement Co., Ltd. Portland cement, 805kg of Yeoju Instructor, 1021kg of coarse aggregate, and 182kg of water including cement admixture. The addition amount of each cement admixture is an experimental result when it is 0.3 weight% with respect to cement solid content.

TABLE 1 Performance Characteristics of Concrete Containing Dispersant and Conventional Dispersant of the Present Invention

From the results shown in Table 1 above. The concrete mixture to which the concrete dispersant prepared in Preparation Example 1-3 is added has higher dispersibility and smaller slump loss, and air entrainment according to the air entraining effect and the change over time than the concrete mixture using the dispersant without the manufacturing process of the present invention. The effect reduction was also clearly observed. It was also possible to obtain concrete with higher mechanical strength.

Example 3 Dispersibility Comparison of Inorganic Materials

In order to confirm the dispersibility effect on the inorganic substances of the dispersant samples prepared in Preparation Example 1-3, the performance test was performed by adding them to iron oxide, and the test results are shown in FIGS. 2 to 4.

0.5 g of iron oxide having passed through 300 mesh was added to a 500 ml aqueous solution, and 6 ppm of each of the dispersant samples prepared in Preparation Examples 1-3 was added thereto, followed by stirring for 1 hour. The dispersibility of each dispersant with time was determined by ultraviolet spectroscopy. (UV spectroscopy, Transmittance 600nm) was used.

From the results shown in FIGS. 2 to 4. The dispersing system to which the dispersing agent prepared in Preparation Example 1-3 was added exhibited lower permeability than the dispersing system using the LS, PS, and NSF dispersing agents as standard, and the characteristic of the dispersing agent prepared according to the present invention suppressed the aggregation of the iron oxide particles. It can be seen that excellent dispersibility.

As mentioned above, the results of the characteristic test of the dispersant prepared according to the method of the present invention demonstrate that the dispersant has a higher dispersibility than the conventional dispersant.

In addition, the method according to the present invention can improve the fluidity rate and prevent the deterioration of fluidity over time while increasing the water-resistance rate compared to the existing concrete dispersant, and at the same time, the new concrete properties such as the air entrainment effect and the air entrainment stability are improved. The inventors have reconstructed their performance dramatically and also found excellent performance as a fluidizing agent that can be widely applied to the dispersion system of fine minerals. Therefore, dispersing agents such as coal slurry and gypsum slurry, fluidizing agents for brick and sidewalk block manufacturing, and groundwater development The value added as a dispersant such as a water dispersant and a dye dispersant will be very high.

Claims (3)

Lignin sulfonate (LS), Lphthal Sulfonate (NSF), Naphthalene Sulfonated Formaline Condensates (MSF), Melamine Sulfonated Formaline Condensates (MSF), Petroleum Sulfonate (PSate, Petroleum) The dispersant raw material selected from the group consisting of polycarboxylic acids is selected from the group consisting of Fenton reagent, H ₂ O ₂ , KMnO ₄ , K ₂ Cr ₂ O ₇ , O ₃ and K ₂ S ₂ O ₈ . Oxidizing the dispersant raw material by adding and stirring an oxidizing agent. The method of claim 1, further comprising, after said step, mixing at least one material selected from the group consisting of an air entrainer, a slump maintainer, an antifoaming agent, a quickener, a retardant, a bleeding inhibitor, and a fireproofing agent. . The preparation according to claim 1 or 2, wherein the prepared dispersant comprises a concrete water reducing agent, a fluidizing agent, a coal slurry dispersant, a fluidizing agent for producing bricks and sidewalk blocks, a diluent in groundwater development, a gypsum slurry dispersant or a dye dispersant. Way.

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