KR20010074299A - Admixture of concrete - Google Patents

Abstract

PURPOSE: An additive useful in preparation of concrete is provided to serve as high performance water-reducing agent by containing controlled content of particular monomer and having desired range of number mean molecular weight of water soluble acrylic acid additive. CONSTITUTION: The additive comprises hydrophobic monomer(A) including acrylonitrile, methyl(metha)crylate, butyl(metha)crylate, isobutyl(metha)crylate, propyl(metha)crylate, (methyl)styrene, vinylacetate; methacrylic acid(B); maleic anhydride(C); and at least two acrylic monomers selected from (poly)alkyleneglycol maleic ester, (poly)alkyleneglycol (di)maleic ester prepared by reacting maleic anhydride and (poly)alkyleneglycol(D) represented by the formula(1) (wherein R1 is -COOH, R2 is-H, R3 is oxyalkylene group having 1-3 carbon atoms; and R4 is maleic acid group. And n is mean added mole numbers ranged from 1-300).

Description

Additive for concrete {Admixture of concrete}

The present invention relates to the production of acrylic acid additives for concrete. More specifically, the present invention relates to a water-soluble acrylic acid additive which acts as a high performance water reducing agent which is a concrete chemical admixture, but has acrylic acid, maleic acid, polyethylene glycol, and hydrophobic monomers controlled in a specific range ratio and the number average molecular weight is adjusted in a certain range.

Chemical admixture for concrete is used to improve the quality and workability of concrete and to impart desired properties. It is an important material currently occupying the position as the fourth component in concrete after cement, water, and aggregate. The majority of chemical admixtures are air entranining agents, entraining agents, and high performance reducing agents. Air emollients, air entrainers, and high-performance sensitizers are all chemically belonging to surfactants, and depending on the properties of the surfactants, such as foaming, dispersing, wetting, etc. If it is excellent in dispersing and wetting action, it is used as air reducing sensitizer.

Air entrainer is an admixture discovered by accident in the 1930's. It uniformly entrains fine spherical air bubbles in concrete and improves workability of concrete by ball bearing effect of fine bubbles in the solid state. Increasingly, it is an essential admixture used more than in temperate regions in winter. The main components of air emulsifiers are wood resin dyes, synthetic detergents, sulfonated lignin salts, petroleum salts, fatty acids and resin acids and salts thereof, organic salts of sulfonated hydrocarbons, and the like. , Cationic and zwitterionic air entrainers. Mainly used in concrete are anionic surfactants.

High-performance sensitizers are admixtures that adsorb on the surface of cement particles to disperse the particles with electrostatic or granular repulsive forces to disperse the cement particles in a relatively small amount of water. This is because the air bubbles in the concrete increases the resistance to freeze-thaw when only air entraining agent is used, but since these bubbles act as defects, the strength of the concrete may be lowered. It is a admixture for the purpose of increasing the strength by the effect of reducing the cement ratio. Substances used as a water reducing agent include lignin sulfonic acid salts and oxycarboxylic acid salts. The air entrainer is a combination admixture that allows the air entrainer and the agent to be properly mixed in advance to achieve the desired bubble entraining and dispersing effects.

Although the quality improvement of the concrete was able to be improved to some extent by using the water reducing agent or the air entraining water reducing agent, there was a limit in producing high strength concrete. In order to achieve high strength, it is necessary to keep the unit cement quantity as high as possible, while keeping the unit quantity as low as possible. Such performance should be obtained by improving dispersibility. However, in order to improve dispersibility by using a reducing agent, the amount of addition of the reducing agent should be increased. However, when lignin sulfonic acid salt or oxycarboxylic acid salt, which is a conventional water reducing agent, is used, there is a problem in that the amount of air is increased or the hydration of cement is delayed.

Therefore, sulfonate formaldehyde condensates of naphthalene or melamine were developed in Japan and West Germany in the 1960s as a new sensitizer that does not significantly affect the increase of air volume or the hydration reaction. Since it has less natural action of entraining air or cement hydration even if the amount of additive is increased more than 4 times than existing water reducing agent, it can realize 5 ~ 8 times water reducing effect than water reducing agent. It was classified under a new name. Since then, the rapid development of industrial society has led to the construction of large-scale and ultra-high-rise buildings, which has resulted in the use of high-strength concrete. However, when the high performance water-reducing agent is used, in the process of mixing concrete in a ready mixed concrete plant and transporting it to the construction site, a slump loss occurs in which the slump of concrete decreases rapidly with time, and the workability is drastically reduced. This caused difficulties such as clogging of pumps and excessive energy consumption. In order to improve this, in the case of adding excess water in the field and re-bending, the strength of the hardened concrete is lowered, which seriously affects the durability of the concrete. This is because the effect of dispersing cement particles by the electrostatic repulsive force of adsorption and adsorbing naphthalene or melamine-based high performance sensitizer on the surface of cement particles becomes thinner due to the large amount of electrolyte generated by the hydration of cement. This is because they are buried in cement hydrate and disappear.

As a method for solving this problem, a cement composition characterized by using an emulsified copolymer containing α, β-monoethylenically unsaturated carboxylic acid as an essential monomer is disclosed in Japanese Patent Application Laid-Open No. 3-131553. It is described. The cement composition described in the above publication exhibits a very high water retention property by gelling in an alkaline atmosphere, and can solve problems such as form collapse and dry out during demolding by the action of the water retention property. Further, a high performance water reducing agent composition comprising an aqueous mixture of a vinyl polymer emulsion and a water-soluble vinyl copolymer comprising an aqueous mixture whose viscosity is twice or more in a region of pH 9 or more is disclosed in Japanese Patent Application Laid-Open No. 9-71447. It is described. The high performance water reducing agent composition described in the above publication can impart high fluidity and material separability as desired to the cement blend prepared using the high performance water reducing agent composition. Moreover, the additive for high dynamic concrete which contains the copolymer emulsion which has the free carboxyl group obtained from a monomer component in a polymer chain is described in Unexamined-Japanese-Patent No. 8-225353. The invention of the high-flow concrete additive described in the above publication is to be able to produce a high-flow concrete having excellent fluidity, filling properties, and also excellent separation resistance. In such conventional cement additives, rather than the main components having direct and important functions in having various complex functions and performances in the cement blend, they are used arbitrarily or incidentally, and other copolymerizable with these main components. As one of the monomers, acrylic acid alkyl esters are described. However, for the alkyl acrylate ester which is only one of these other monomer components, unlike the main component, it is not very important what effect it can have on the cement compound, and only Japanese Patent Application Laid-Open No. H3-331553 In the specification of the publication, good results were obtained when the acrylic acid alkyl ester was prepared as a main component. In addition, a water reducing agent copolymerized with an acrylic monomer having a polyoxyalkylene group was developed and its performance was superior to that of the conventional one. However, there is a disadvantage that the price of a monomer such as polyoxyalkylene (meth) acrylate is expensive.

The present invention relates to the production of acrylic acid additives for concrete. More specifically, the present invention relates to a water-soluble acrylic acid additive which acts as a high performance water reducing agent, which is a concrete chemical admixture, and has acrylic acid, maleic acid, polyethylene glycol, and hydrophobic monomer values adjusted in a specific range ratio and a number average molecular weight adjusted in a certain range.

Essential monomers used in the preparation of the above additives for concrete include hydrophobic monomers such as acrylonitrile and methyl (meth) acrylate / (meth) acrylic acid / maleic anhydride / (poly) alkylene glycol maleic acid esters, and (poly) alkyl. Lenglycol (di) maleic acid ester, wherein (poly) alkylene glycol maleic acid ester, (poly) alkylene glycol (di) maleic acid ester, is prepared by half maleic anhydride with (poly) alkylene glycol and (poly) alkyl It is to prepare an additive for concrete of a multicomponent copolymer or a salt of a copolymer, characterized in that it contains at least one acrylic monomer selected from len glycol (di) maleic acid ester.

The present invention is a hydrophobic monomer / (B) (meth) acrylic acid / (C) maleic anhydride / (D), such as (A) acrylonitrile, methyl (meth) acrylate as essential monomer components in the production of additives for concrete (Poly) alkylene glycol maleic acid esters, (poly) alkylene glycol (di) maleic acid esters are prepared by half maleic anhydride with (poly) alkylene glycols and are selected from (poly) alkylene glycol (di) maleic acid esters. A multicomponent copolymer or a salt of a copolymer is provided as an additive for the concrete containing at least an acryl monomer in a form and including (poly) alkylene glycol maleic acid ester and (poly) alkylene glycol (di) maleic acid ester.

Polymers useful in the practice of the present invention are at least one hydrophobic monomer selected from (A) acrylonitrile, methyl (meth) acrylate, etc./(B) at least one monomer selected from (B) (meth) acrylic acid / (C) maleic anhydride / ( D) (poly) alkylene glycol (meth) acrylate, (poly) alkylene glycol di (meth) acrylate, (poly) alkylene glycol maleic acid ester, (poly) alkylene glycol (di) maleic acid ester It is a water-soluble polymer of the salt of the multicomponent polymer or multicomponent polymer which superpose | polymerizes the above monomer and contains three or more vinylic monomers. Hydrophobic monomer (A) is acrylonitrile, methyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, propyl (meth) acrylate, (methyl) styrene, vinyl acetate, etc. The alkylene glycol maleic acid ester and the (poly) alkylene glycol (di) maleic acid ester (D) are prepared by half maleic anhydride with (poly) alkylene glycol, and the (poly) alkylene glycol (di) maleic acid ester It is a compound represented by general formula (I).

(I)

(Wherein R1 represents -COOH, R2 represents -H and R3 represents an oxyalkylene group having 2-3 carbon atoms and R4 represents a maleic acid group. N represents an average added mole number of the oxyalkylene group and represents a number from 1 to 300.) )

Examples of the polyalkylene glycol of the (poly) alkylene glycol maleic acid ester and the (poly) alkylene glycol (di) maleic acid ester (D) used in the present invention include (poly) ethylene glycol, (poly) ethylene glycol (poly) propylene glycol, (Poly) propylene glycol, (poly) ethylene glycol (poly) butylene glycol, (poly) ethylene glycol (poly) propylene glycol (poly) butylene glycol, (poly) butylene glycol, methoxy (poly) ethylene glycol , Methoxy (poly) ethylene glycol (poly) propylene glycol, methoxy (poly) propylene glycol, methoxy (poly) ethylene glycol (poly) butylene glycol, methoxy (poly) ethylene glycol (poly) propylene glycol ( Poly) butylene glycol, methoxy (poly) butylene glycol, ethoxy (poly) ethylene glycol, ethoxy (poly) ethylene glycol (poly) propylene glycol, ethoxy (poly) propylene glycol, ethoxy (poly) ethylene Glycol ( L) butylene glycol, ethoxy (poly) ethylene glycol (poly) propylene glycol (poly) butylene glycol, ethoxy (poly) butylene glycol, phenoxy (poly) ethylene glycol, phenoxy (poly) ethylene glycol (Poly) propylene glycol, phenoxy (poly) propylene glycol, phenoxy (poly) ethylene glycol (poly) butylene glycol, phenoxy (poly) ethylene glycol (poly) propylene glycol (poly) butylene glycol, phenoxy (Poly) butylene glycol etc. can be mentioned and it can use these 1 type, or 2 or more types. It is preferable that especially ethylene glycol is contained like (poly) ethylene. The average added mole number of the oxyalkylene group is 1 to 300 and preferably 10 to 250.

The ratio of the three components described above is preferably 0.5 to 30 mol% for component (A), 20 to 70 mol% for component (B), 20 to 70 mol% for component (C) and (D) Components in the range of 20 to 70 mole% can be used. From the viewpoint of the availability of the raw materials, the ease of copolymerization reaction and the effect as a special surfactant, 0.5 to 30 mol% of hydrophobic monomers (A) such as methyl (meth) acrylate, 20 to 60 mol% of (meth) acrylic acid (B), It is preferable to use the copolymer which consists of 20-60 mol% of maleic anhydride (C), 20-60 mol% of (poly) alkylene glycol maleic acid ester, and (poly) alkylene glycol (di) maleic acid ester (D).

Polymerization methods for obtaining the copolymer include ion polymerization reaction, radical polymerization reaction, thermal polymerization reaction, radiation polymerization reaction, and the like, but a double radical polymerization reaction is preferable.

As the polymerization catalyst, radical polymerization such as various organic peroxides (e.g. benzoyl peroxide), organic hydroxide peroxides, aliphatic azobis compounds (e.g. azobisisobutyronitrile), and water-soluble persulfates (e.g. persulfate) There is a reaction initiator. The anionic water-soluble polymers used in the present invention preferably have a relatively low molecular weight (i.e., provide a low viscosity when made into an aqueous solution), so that water-soluble peracids (e.g. ammonium persulfate or potassium peroxide) and water-soluble reducing agents ( Most preferably using a radical forming redox catalyst prepared by blending, eg, sulfite). Such radical forming redox catalysts are generally added to the reaction system in the form of an aqueous solution. Each of the catalyst, ie, the water soluble peracid and the water soluble reducing agent, can be added in an amount of 0.01 to 10 parts per 100 parts of the monomer component.

In order to control the molecular weight of the polymer to be obtained, the reaction may be carried out by mixing one of various compounds known as a chain converting agent such as alkyl mercaptan and the like into a small amount of reaction system. When the vinyl monomers are polymerized in aqueous solution, the monomers containing acid groups in the form of free acids or partial or full salts can be polymerized. When using a salt monomer, it can be used in the form of alkali metal salt, alkaline earth metal salt, ammonium salt, lower amine salt, hydroxyalkylamine salt, etc. When preparing an anionic water-soluble polymer in an aqueous system according to the radical polymerization method, the temperature of the system increases adiabatic due to the sudden generation of heat of polymerization after the addition of the catalyst and therefore the polymerization is completed in a relatively short time. In order to prevent boiling of the system from the viewpoint of the polymerization heat generated by the monomers, the polymerization reaction is generally carried out using 5 to 30% by weight of each monomer.

The obtained water-soluble polymer is measured by gel permeation chromatography (calculated using dextran as a reference molecular weight) and has a molecular weight of 1,000 to 10,000,000.

Example 1

In the method for preparing a water-soluble polymer, 200 g of methoxy polyethylene glycol (molecular weight: 2000) and 5.4 g of musmaleic acid are added to a three-necked flask, and the mixture is mixed for half an hour at 70 ° C. to synthesize methoxy polyethylene glycol maleic acid, and the methoxy polyethylene glycol maleic acid described above. 30 g of ester are dissolved in 270 g of deionized water and 40 g of 98% acrylic acid and 20 g of acrylonitrile are added. The mixture is stirred and mixed to make a homogeneous aqueous solution, and the reaction system is heated to 30 ° C., while maintaining the temperature, 6 g of ammonium persulfate is added, and after 5 minutes, 3 g of aqueous sodium hydrogen sulfide solution is further added. The temperature of the system rises to 75 ° C in 30 minutes. After maintaining the temperature of the system at 75 ° C. for 1 hour, the system was cooled, and a 20% aqueous sodium hydroxide solution was added to adjust the pH thereof to 6 to 8 to obtain a 40% aqueous solution of the water-soluble polymer. The aqueous solution has a viscosity of 210pcs at 25 ° C.

EXAMPLES 2-4

The same conditions as in Example 1 were carried out as Table 1 below.

Example Acrylic acid (AA) Polyethylene Glycol 2000 Maleic acid (MA) Vinyl acetate water Viscosity (cps) 2 50 50 50 50 300 190 3 75 75 50 - 300 150 4 50 75 75 - 300 145

EXAMPLE 5 The change with time of the slump and the amount of air.

After mixing in the concrete mixer and draining to the bibeam plate, after measuring the slump and air volume twice, the remaining concrete is put into the movable mixer, the shaft is tilted 20 to 30 degrees and maintained at a speed of 2 to 3 revolutions per minute. 60 minutes after the start of the mixing, the concrete is discharged to the bibeam plate, and the average value is measured after twice the slump and air volume after re-beaming. The compounding quantity is as Table 2.

combination W / C (%) S / A (%) W C S G Admixture (C × 1%) Standard compounding ratio 36.7 48 145 395 810 960 3.95 bol combination 36.7 48 8.7 23.7 52.5 57.6 0.237

W: Tap water, C: General photoland cement HD working ratio of H, A, S mixed cement, S (sand): assembly rate 2.90, using washing thread, G (gravel): assembly rate 6.80, Taishan

The result measured in Example 5 is as follows.

Sample name Reduction rate Air volume (%) Slump (cm) 0min 60min 0min 60min Standard concrete · 1.5 0.9 21 9.0 Example 1 21 50 3.4 21.5 18.5 Example 2 22 4.8 3.8 24.5 22.5 Example 3 25 5.0 3.8 25 23.0 Example 4 21 4.7 3.7 24 22.5 Comparative Example 1 22 5.0 4.3 21.5 21.5 Comparative Example 2 21.5 5.0 4.1 21.5 21.0

Comparative Example 1: NSF, (sodium napthalene sulfonated formaldehyde condenstation)

Comparative Example 2: MSF (sodium melamine sulfonated formaldehyde condenstation)

Example 6 Compressive Strength

According to KS F 2405 standard, it was carried out at 3 days, 7 days and 28 days, and the average values of the three specimens and the strength measurement results for each age are shown in Table 4 as the compressive strength of the concrete.

Sample name Compressive strength (kg / ㎠) 3 days 7 days 28th Standard Concrete 142 269 362 Example 1 201 360 525 Example 2 201 359 530 Example 3 203 323 588 Example 4 204 333 506 Comparative Example 1 195 315 405 Comparative Example 2 198 322 415

The present invention can be efficiently produced additives for concrete without special equipment, the processing cost is low, it is possible to produce the additive of the desired molecular weight in a short time and can be produced in high concentrations is much more economical.

Claims (2)

Hydrophobic monomer / (B) (meth) acrylic acid / (C) maleic anhydride / (D) (poly) such as (A) acrylonitrile and methyl (meth) acrylate, respectively, as essential monomer components in preparing the additive for concrete Alkylene glycol maleic acid esters, (poly) alkylene glycol (di) maleic acid esters are prepared by half maleic anhydride with (poly) alkylene glycols and at least two types of acrylics selected from (poly) alkylene glycol (di) maleic acid esters. An additive for concrete of a multicomponent copolymer or salt of a copolymer containing a monomer and comprising (poly) alkylene glycol maleic acid ester and (poly) alkylene glycol (di) maleic acid ester. The hydrophobic monomer (A) used in claim 1 is acrylonitrile, methyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, propyl (meth) acrylate, (methyl) styrene, The vinyl acetate and the like (poly) alkylene glycol maleic acid ester, (poly) alkylene glycol (di) maleic acid ester (C) is a compound represented by the following general formula (I) (I) (Wherein R1 represents -COOH, R2 represents -H and R3 represents an oxyalkylene group having 2-3 carbon atoms and R4 represents a maleic acid group. N represents an average added mole number of the oxyalkylene group and represents a number from 1 to 300.) ) Examples of the polyalkylene glycol of the (poly) alkylene glycol maleic acid ester and the (poly) alkylene glycol (di) maleic acid ester (C) include (poly) ethylene glycol, (poly) ethylene glycol (poly) propylene glycol, and (poly) propylene. Glycol, (poly) ethylene glycol (poly) butylene glycol, (poly) ethylene glycol (poly) propylene glycol (poly) butylene glycol, (poly) butylene glycol, methoxy (poly) ethylene glycol, methoxy ( Poly) ethylene glycol (poly) propylene glycol, methoxy (poly) propylene glycol, methoxy (poly) ethylene glycol (poly) butylene glycol, methoxy (poly) ethylene glycol (poly) propylene glycol (poly) butylene Glycol, methoxy (poly) butylene glycol, ethoxy (poly) ethylene glycol, ethoxy (poly) ethylene glycol (poly) propylene glycol, ethoxy (poly) propylene glycol, ethoxy (poly) ethylene glycol (poly) Butylene Glycol, Methoxy (poly) ethylene glycol (poly) propylene glycol (poly) butylene glycol, ethoxy (poly) butylene glycol, phenoxy (poly) ethylene glycol, phenoxy (poly) ethylene glycol (poly) propylene glycol, phenoxy (Poly) propylene glycol, phenoxy (poly) ethylene glycol (poly) butylene glycol, phenoxy (poly) ethylene glycol (poly) propylene glycol (poly) butylene glycol, phenoxy (poly) butylene glycol, One or two or more of these species are used, and the average added mole number of the oxyalkylene group is 1 to 300, and 20 to 70 mol% of the hydrophobic monomer (A), 20 to 60 mol% of (meth) acrylic acid (B), and ( Poly) alkylene glycol (meth) acrylate, (poly) alkylene glycol di (meth) acrylate, (poly) alkylene glycol maleic acid ester, (poly) alkylene glycol (di) maleic acid ester (C) 0.5 to 30 For concrete consisting of monomeric components in mole% Gauze