JP3124625B2 - Method for curing underwater curing of polymer-emulsion-containing cement using reactive surfactant - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for curing underwater curing of a polymer-emulsion-containing cement using a reactive surfactant. More particularly, the present invention relates to a method of curing and hardening cement which is useful as a cement hardened material for repairing concrete structures related to marine or water use, which is submerged immediately after construction.

[0002]

2. Description of the Related Art Conventionally, a polymer for mixing ordinary cement is used.
If the cement (mortar, concrete) mixed with the emulsion is cured in water immediately after kneading and hardened, the polymer particles do not sufficiently fuse in the hardened cement, so the strength expression is poor, and the effect of mixing the polymer is poor. Does not appear. Therefore, in order to cure the polymer-containing cement in water, first, air-dry curing or wet-air curing is performed to advance the formation of a fused film of polymer particles to a certain degree, and then, the cement is treated in water to cure in water. The sum reaction proceeds further. Finally, curing by air-drying is performed to complete the fusion of the polymer and the formation of a film, thereby developing strength. Preferred curing conditions for such polymer-loaded cements are, for example, JI
It is listed as standard curing conditions in SA6203. Another problem with the prior art is that the strength of the cement mixed with the polymer emulsion when wetted with water is significantly lower than in the air-dried state. Therefore, it is considered unsuitable to apply a polymer-containing cement (mortar, concrete) to a case where the main curing condition is water or a place where it is always immersed in water.

[0003] The drawbacks of the above prior art are due to the following reasons. Conventional cement admixture polymer
Emulsions are used to obtain mixing stability with cement.
Contains excess surfactant, so water will enter once in the air-dried state even if the polymer particles are firmly fused and bonded to cement, aggregate, etc. in the cured product and exhibit good strength Then, the binding force is weakened by a hydrophilic component such as a surfactant and the strength is reduced. In addition, from the viewpoint of the composition of the polymer, even if the conventional polymer is firmly fused to cement or aggregate in the air-dry state, the polymer itself absorbs and swells in the presence of water. There is a disadvantage that the bonding force is greatly reduced. Remedies for the above disadvantages include a method of using a cement water reducing agent and a polymer emulsion in combination to reduce and strengthen the water / cement ratio, to increase the fusion bonding strength of the polymer, and to increase the resistance to water. For this reason, a method of mixing a polymer having a high glass transition temperature and curing the polymer by heating to a temperature equal to or higher than the glass transition temperature of the polymer by steam curing during curing (Japanese Patent Application Laid-Open No. 52-6)
No. 2332). However, this method also has a drawback that if curing in water is performed after curing, various strengths cannot be avoided. Therefore, attempts have been made to reduce the content of the surfactant contained in the polymer emulsion as much as possible. For example, a method of increasing the copolymerization ratio of acrylic acid or methacrylic acid has been adopted. In this method, the cement mixing stability of the polymer particles can be maintained with a small amount of the surfactant, and the strength in the air-dried state is good. However, when the polymer particles are immersed in water for a long period of time, the bonding force of the polymer particles is weakened by the hydrophilicity of the functional group, and the strength of immersion in water is significantly reduced.

[0004]

Normally, ordinary cements (mortars, concretes) which do not contain a polymer exhibit sufficient strength by being cured in water from the early stage of curing. On the other hand, as described above, it is unsuitable for the conventional polymer emulsion-containing cement (mortar, concrete) to be cured in water immediately after kneading. When performing underwater curing, a process of air-dry curing or wet-air curing must be incorporated into the curing process. Also,
Conventional polymer-mixed cement (mortar, concrete
Even if g) is sufficiently developed under appropriate curing conditions, the difference between the strength when air-dried and the strength when immersed and moistened in water is extremely large. Therefore, there is a drawback that a sufficient effect cannot be obtained even when the conventional polymer-emulsion mixed cement is always used for a hydraulic structure, a marine structure, or the like which is immersed in water or seawater.

[0005]

SUMMARY OF THE INVENTION The present invention relates to an ethylene-based or methyl methacrylate-based monomer of 20 to 99.5% by weight, an alkyl acrylate-based monomer of 80% by weight or less, and an ethylenically unsaturated monomer. 0.3 to 6% by weight of a saturated carboxylic acid and 0.2 to 5% by weight of a silane-containing vinyl-based, silane-containing methacryl-based or silane-containing acrylic monomer
The glass transition of a polymer obtained by emulsion polymerization of a monomer mixture comprising a reactive surfactant of 4% or less based on all monomers and a necessary amount of water in the presence of a polymerization initiator. A polymer emulsion having a temperature of -30 to 100 ° C. and a water reducing agent selected from melamine-based, naphthalene-based, or polycarboxylic acid-based ones added to the above polymer in an amount of 1 to 10% and mixed with cement. A method for curing a cement mixed with a polymer emulsion using a reactive surfactant, wherein the cement is mixed in a mortar or a concrete at 3 to 50% and cured in a temperature range of 50 ° C. or less. Thus, the disadvantages of the prior art can be eliminated. The kind and ratio of monomers used for so-called hard monomers such as styrene-based or methyl methacrylate-based monomers and so-called soft monomers such as alkyl acrylate-based monomers are determined by polymerization reaction. Since the glass transition temperature of the polymer obtained by the above is governed, it is appropriately selected to adjust the target glass transition temperature. When the ratio of the hard monomer increases, the polymer has a high glass transition temperature, and when the ratio of the soft monomer increases, the polymer has a low glass transition temperature. A polymer having a low glass transition temperature is useful for repair cement admixture of a surface layer of a marine concrete structure in which seawater constantly penetrates, and the glass transition temperature is preferably in the range of -30C to 20C. On the other hand, a polymer having a high glass transition temperature is suitable for mixing a cast-in-place concrete structure having a large cross-sectional thickness or for mixing a molded product of a concrete structure in a factory. Temperature is 20-10
A range of 0 ° C. is preferred.

As described above, an appropriate polymer glass transition temperature is selected depending on the application and the method. It is to be noted that a part of the hard monomer may be replaced with methylstyrene monomer, butyl methacrylate or the like. Also,
A part of the soft monomer may be replaced with 2-ethylhexyl methacrylate or the like. Representative examples of the ethylenically unsaturated carboxylic acid monomer (COOH-based monomer) include acrylic acid and methacrylic acid. The COOH-based monomer is copolymerized to impart stability to the polymer particles when the polymer emulsion is kneaded with cement. As described above, it is not preferable to increase the copolymerization amount of the acid monomer more than necessary because the strength decrease when wetted with water increases. However, if the amount is too small, the stability of the polymer particles is impaired. A suitable copolymerization amount is 1 to 4%. As the COOH-based monomer, the above two types of monomers are the most typical, but crotonic acid, maleic acid, itaconic acid and the like can also be used. Two or more COOH-based monomers may be used in combination. Note that a part of the COOH-based monomer can be used instead of acrylamide or methacrylamide. The silane-containing vinyl-based, silane-containing methacryl-based, or silane-containing acrylic monomer is a component that plays an important role in firmly bonding polymer particles to the surface of cement or aggregate during the curing process in water. The higher the copolymerization amount, the better the cured cement material having good physical properties. However, it is not advisable to increase the copolymerization amount too much, because if the copolymerization amount is increased, the cost will increase significantly and the polymerization reaction yield of the polymer will deteriorate. The preferred copolymerization amount is 0.3-3%, more preferably 0.7-2%. Vinyltris (β-methoxyethoxy) silane and γ-methacryloxypropyltrimethoxysilane are useful as the silane-containing vinyl-based or silane-containing methacryl-based or silane-containing acrylic-based monomer. In addition, vinyl triethoxysilane and the like can be used. Among them, vinyl tris (β
Methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane. Examples of the reactive surfactant include sulfoethyl methacrylate sodium salt, polyoxyethylene nonylpropenyl phenyl ether,
Examples include ammonium polyoxyethylene nonylpropenylphenyl ether sulfate, sodium alkyl allyl sulfosuccinate, ammonium allyl glycidyl lauryl sulfosuccinate, and polyethylene glycol methacrylate. Of these, anionic ones are preferred. The amount used is not more than 4% in solid content with respect to the monomer, more preferably 0.5 to 1%.
When the use amount of the above-mentioned reactive surfactant exceeds 4%, the bonding between the polymer particles and the surface of the cement or the aggregate in the underwater curing process is hindered, and the development of strength is reduced. On the other hand, 0.3
% Is not preferred because a stable polymer emulsion usable for cement mixing cannot be obtained.

[0007] In the emulsion polymerization reaction, the above-mentioned mixed monomer having a specific monomer composition is put into a dropping funnel, a required amount of water and a specific amount of a specific reactive surfactant are charged into a flask of a reaction tank, and a polymerization catalyst is further added. And then adding a salt of a peroxide, for example, potassium persulfate, ammonium persulfate, sodium persulfate or the like at a ratio of 0.1 to 1% based on the monomer, and then heating the reaction vessel to 50 to 80 ° C. While keeping the temperature constant, add 2 parts of the mixed monomer from the dropping funnel.
The polymerization reaction is carried out by adding to the reaction vessel at a constant dropping rate over a period of about 5 hours. The reaction temperature is kept at 1
Holding for ２2 hours gives a polymer emulsion with a specific glass transition temperature. The above emulsion polymerization reaction conditions are very generally industrially carried out, and there are no special conditions required for carrying out the present invention. After the emulsion polymerization reaction, the pH of the specific polymer emulsion obtained is
Is adjusted with ammonia water or caustic soda, etc.
Filter with a mesh filter cloth to obtain the polymer emulsion of the present invention. As the polymer emulsion, solid content = 30 to 60%, viscosity = 30 to 10,000 cps, PH
= 5 to 9 polymer having a particle size of 0.1 to 0.5 µm. After the polymerization reaction, a nonionic surfactant, for example, an ethylene oxide adduct of nonylphenol is added within the range of 0 to 2% with respect to the polymer solid content in order to supplement the cement mixing stability of the obtained polymer emulsion. Is also good.

Next, as a cement water reducing agent to be added to a polymer emulsion having a glass transition temperature of -30 ° C. to 100 ° C. obtained by a polymerization reaction, the reaction initial condensate of melamine and formalin is sulfonated to an alkali salt. A melamine-based water reducer, a naphthalene-based water reducer obtained by sulfonating an initial reaction condensate of naphthalene and formalin into an alkali salt, or a polycarboxylic acid-based high-performance water reducer is preferred. The mixing amount of the water reducing agent is 1 to the polymer solid content.
10% is good. Preferably it is 3-7%. Two or more water reducing agents may be used in combination. Usually, the cement water reducing agent is supplied in the form of an aqueous solution having a concentration of 20 to 50%, and the compounding into the polymer emulsion may be carried out while stirring the polymer emulsion. It is also a feature of the present invention that the premixing of the water reducing agent with the polymer emulsion dramatically improves the stability of the polymer emulsion in mixing with cement. Probably, a part of the water reducing agent molecules is adsorbed on the surface of the polymer particles to maintain the mechanical and chemical stability of the polymer particles during kneading with the cement. Of course, when kneading the polymer emulsion of the present invention with no water reducing agent added to the cement, without adding the water reducing agent to the polymer emulsion in advance, the water reducing agent is added separately when mixing the polymer emulsion into the cement. Needless to say, the desired cured product can be obtained. The amount of the specific polymer emulsion of the present invention thus mixed into the cement is preferably 3 to 50% by solid content based on the cement. If it is less than 3%, there is no effect of mixing the polymer, and if it is 50% or more, the amount of the polymer becomes too large, and it becomes difficult to obtain a large strength. The most suitable loading is 5-15%.

As the cement, Portland cement is generally used in many cases, but high strength cement, alumina cement, jet cement and the like can also be used. As the aggregate, all the aggregates used for ordinary mortar and concrete can be used. The ratio of cement to aggregate can be used as well as the ratio used for ordinary mortar and concrete. The amount of the kneading water is usually added so as to provide an appropriate workability according to the purpose of mortar or concrete application. However, in the method of the present invention, an extremely small amount of water can be used. The antifoaming agent may be previously added to the polymer emulsion, if necessary, or may be separately measured and added when the specific polymer emulsion is kneaded with the cement. The addition of an antifoaming agent is important in adjusting the amount of air in the mortar or concrete, and in order to obtain a high-strength cured product, an effective antifoaming agent should be used so that the amount of air decreases. You have to choose. Most commercially available defoamers for cement-mixed polymers can be used, but it is preferable to use an aqueous emulsion type defoamer in an amount of 0.2 to 1% based on the specific polymer of the present invention. . Under water-curing conditions, the polymer-mixed cement of the present invention may be cured in water immediately after kneading, and the strength is sufficiently developed. Or you may perform wet-air curing for 0 to 12 hours before performing underwater curing. Curing conditions may be adopted in which moist air curing or air-dry curing is appropriately incorporated during the underwater curing period. In any case, it is a feature of the present invention that sufficient strength is exhibited under the curing conditions mainly based on underwater curing. The thus obtained hardened cement material of the present invention exhibits extremely high bending and compressive strength even when wet with water. Large strength can be expected even at the young age. Also,
According to the method of the present invention, it can be applied to pruning,
It is also possible to carry out strong adhesion by passing the specific polymer-mixed cement of the present invention to a cement-based adherend submerged in water. It is needless to say that the bending, compression and adhesive strengths are further increased when the wet hardened cement of the present invention is placed in an air-dried state. Although it is the temperature when performing underwater curing, if it is in the range of 0 to 50 ° C., the polymer-mixed cement of the present invention may be immersed in water immediately after kneading to perform underwater curing.

[0010]

In the past, it has been considered inappropriate to cure and harden a cement mixed with a polymer emulsion in water. In such a case, the cement must be air-cured or wet-cured once to form a film. Glass transition temperature 55 ° C
Although steam curing and the like are unavoidable in the above, in the method of the present invention, there is a criticality in the selection and content of the reactive surfactant, and among the surfactants contained in the polymer emulsion, It works to reduce the amount of surfactant dissolved in the aqueous layer. Although the detailed mechanism of the underwater curing and curing method of the present invention is not clear, the bonding strength with cement or aggregate is increased by copolymerization of a silane-containing vinyl monomer or the like, and furthermore, a polymer having a high glass transition temperature is produced. It is presumed that the amount of kneading water is reduced by mixing and using a water reducing agent in combination, and such a combination acts to exert a synergistic effect equal to or more than the sum of these.

[0011]

According to the method of curing underwater of a polymer-containing cement according to the present invention, first, the polymer is composed of a specific monomer composition so as to have a specific glass transition temperature and polarity,
The surfactant used for the polymerization reaction is a specific reactive surfactant used in a specific amount to perform an emulsion polymerization reaction to obtain a polymer emulsion having a specific glass transition temperature, and further for a specific cement. Polymer with specific amount of water reducing agent added
A specific amount of the emulsion is mixed with cement to perform a specific curing method.However, a polymer having a specific glass transition temperature and polarity can be cemented or boned under water curing under the same effect as air-dry curing conditions. It is firmly bonded to the surface of the material, and the use of a specific surfactant aids the bonding between the polymer and the cement or the aggregate, and prevents a decrease in strength in a wet state with water under water curing. The coexistence of the cement water reducing agent improves the mechanical and chemical stability of the polymer particles at the time of kneading with the cement, and lowers the water / cement ratio to play a part in achieving high strength. Thus, the cured underwater cured product of the polymer-mixed cement of the present invention exhibits large bending and compressive strength even when wet with water, and a high-strength cured product that cannot be obtained with the conventional polymer cement can be obtained. Therefore, it can be used not only as a skeleton of a concrete structure, but also as a repair material for a defective portion of an underwater concrete structure,
Demonstrate strong adhesive performance. Further, since the polymer is mixed, it is excellent in waterproofness and suppresses penetration of various chemicals, so that it can be used as a chemical-resistant protective material.

[0012]

EXAMPLES In the following examples, the number of blending parts is represented by parts by weight. Example 1 Methyl methacrylate 49 parts Styrene 20 Butyl acrylate 28 Acrylic acid 2 Vinyl tris (β-methoxyethoxy) silane 1 (Nippon Unicar, silane coupling agent A172) The above monomer mixture was dropped into a polymerization reactor. Into the funnel, the following aqueous solution of a reactive surfactant was charged in a flask of the same polymerization reactor, the flask was heated to a constant temperature of 80 ° C., and the monomer mixture was gradually dropped over 3 hours to synthesize a base polymer emulsion (a). And neutralized with aqueous ammonia. Mixed solution in flask: Sodium alkyl allyl sulfosuccinate 0.5 part (Sanyo Chemical, Elminol JS2) Water 100 Ammonium persulfate 0.5 Concentration of the obtained base polymer emulsion (a) = 5
4%, glass transition temperature of polymer = about 60 ° C., PH = 8
Met. A melamine-based water reducing agent was added to the polymer emulsion (b) at the following ratio to obtain a mixed emulsion A. Emulsion A: Base polymer emulsion (a) 100 parts (solid content 54) Melment F10 25% aqueous solution 10 (〃2.5) Total 110 (56.5) Concentration 51.4% Next, ordinary Portland cement, commercially available mountain sand (0.5 moisture
%, FM value 2.70), kneading the mortar mixed with the blended emulsion A, filling the mold into a 4 × 4 × 16 cm form, immediately aging in water at 20 ° C. for 28 days, The compressive strength was measured. Table 1 shows the composition of the mortar and the strength measurement data.

[0013]

[Table 1]

Comparative Polymer 1 is a commercially available styrene / acrylic polymer emulsion having a glass transition temperature of 60 ° C. and excellent water resistance, which can be sufficiently used as a cement admixture. No. 1 in Table 1. Nos. 1 to 3 are comparisons at a constant water / cement ratio of 50%. Nos. 4 to 6 are obtained by comparing the flow values with 160 to 170. N
o. Nos. 1 and 4 are non-mixed mortars. 1 is not suitable for actual construction because the flow value is too small. However, since the water-cement ratio is small, the strength is relatively well developed.
The water cement ratio was increased to make it suitable for construction. 4, the flow value increases but the intensity decreases. No. Nos. 2 and 5 were cured and cured by the method of the present invention. No. 2 shows sufficient strength in underwater curing even though the ratio of water-cement to mortar is the same. No. In No. 5, the water-cement ratio was lowered, but a remarkable increase in strength was observed even after curing in water. No.
Samples Nos. 3 and 6 are comparative examples. Example 2 Monomer mixture: Styrene 67 parts Methyl methacrylate 20 Butyl acrylate 10 Methacrylic acid 2 γ-Methacryloxypropyltrimethoxysilane 1 (Nippon Unicar, silane coupling agent A174) The above monomer mixture In the same manner as in Example 1.
Prepare for The following reactive surfactant aqueous solution was charged into the polymerization reaction tank in the same manner as in Example 1, and the temperature of the reaction tank was set to 75 ° C.
With constant heating, the monomer mixture was slowly added dropwise over 4 hours to synthesize a base polymer emulsion (b) and neutralized with aqueous ammonia. Polyoxyethylene nonylpropenyl phenyl ether 0.5 parts (Daiichi Kogyo Seiyaku, Aqualon RN20) Allyl glycidyl lauryl sulfosuccinate ammonium salt 0.5 (Kao, Latemul S120A) Water 120 Potassium persulfate 0.4 Concentration of the obtained base polymer emulsion (b) 45
%, Glass transition temperature of polymer = about 85 ° C., PH = 8. Next, a base polymer was prepared using ordinary Portland cement and commercially available mountain sand (water content 0.5%, FM value 2.70).
The mortar mixed with the emulsion (b) was kneaded, filled in a 4 × 4 × 16 cm mold, immediately cured in water at 20 ° C. for 28 days, and the flexural strength and compressive strength were measured in a wet state. In kneading the mortar, a naphthalene-based high-performance water reducing agent (43% concentration) is used in combination. Table 2 shows the composition of the mortar and the strength measurement data.

[0015]

[Table 2]

The comparative polymer-2 is a polymer emulsion having a solid content of 45% which is emulsion-polymerized using a styrene acrylic nonionic surfactant and an anionic surfactant having a glass transition temperature of about 85 ° C. of the polymer. . No. No. 2 is cured by the method of the present invention and has extremely good bending and compressive strength after curing in water. Example 3 Monomer mixture: Styrene 40 parts 2 Ethylhexyl acrylate 55 Methacrylic acid 4 Vinyl tris (β-methoxyethoxy) silane 1 The above monomer mixture is charged to a dropping funnel in the same manner as in Example 1. The following aqueous solution of a reactive surfactant was charged into a polymerization reactor in the same manner as in Example 1, the temperature of the reactor was kept constant at 70 ° C., and the monomer mixture was gradually dropped over 4 hours to obtain a base polymer. Emulsion (c) was synthesized and neutralized with aqueous ammonia. Sulfoethyl methacrylate sodium salt 0.3 part (Nippon emulsifier, Antox-MS-2N) Alkyl allyl sulfosuccinate 0.3 (Sanyo Chemical, Elminol JS2) Water 120 Sodium persulfate 0.6 obtained The concentration of the obtained base polymer emulsion C was 45
%, The glass transition temperature of the polymer was about -2 ° C, and the pH was 9. To this base emulsion C, a high-performance water reducing agent was added at the following ratio to obtain a mixed emulsion C. Emulsion C: Base polymer emulsion (c) 100 parts (solid content 45) High performance water reducing agent Melment F10, 25% aqueous solution 10 (〃2.5) Total 110 (〃47.5) Concentration 43.2% Next To ordinary Portland cement, commercially available mountain sand (water 0.5
%, FM value 2.70), kneading the mortar mixed with the blended polymer emulsion A, taking out a 7 × 7 × 2 cm mortar-adhered plate previously immersed in water for 2 days, and 4.5 × The piece was spliced at a size of 4.5 × 1 cm, and pressed down with an iron so as to sufficiently adhere. And immediately 20
Curing was carried out by immersion in water at 28 ° C. for 28 days. After curing,
The test specimen was taken out from the water, and the adhesive strength of the mortar which was continued in a wet state by a shearing method was measured. Table 3 shows the mortar composition and the shear adhesive strength.

[0017]

[Table 3]

The comparative polymer-3 has a solid content of 4 obtained by emulsion polymerization using a styrene acrylic nonionic surfactant and an anionic surfactant having a glass transition temperature of about 0 ° C.
5% polymer emulsion. No. The result of No. 2 is based on the method of the present invention, and exhibits extremely good adhesion even in underwater curing.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI // (C04B 28/02 24:42 24:30 24:22 24:26) (C08F 220/14 212: 08 220: 06 220: 12 230 : 08 218: 16) C04B 103: 30 103: 40 (56) References JP-A-61-136951 (JP, A) JP-A-59-184754 (JP, A) JP-A-3-97644 (JP, A) JP-A-57-63316 (JP, A) JP-A-3-21610 (JP, A) JP-A-63-274443 (JP, A) JP-A-5-65316 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) C04B 28/02-28/08 C04B 24/42 C04B 40/00 C08F 212/08 C08F 220/14 C04B 24:42

Claims (3)

(57) [Claims] 1. A styrene-based or methyl methacrylate-based monomer, 20 to 99.5% by weight, an alkyl acrylate-based monomer, 80% by weight or less, an ethylenically unsaturated carboxylic acid, 0.3 to 6% by weight, and silane. A monomer mixture consisting of 0.2 to 5% by weight of a vinyl-containing, silane-containing methacrylic or silane-containing acrylic monomer, a reactive surfactant of 4% or less based on all monomers, and a necessary amount of water. The glass transition temperature of the polymer obtained by adding a polymerization initiator under the emulsion and emulsion polymerization is -30 to 30
A water-reducing agent selected from melamine-based, naphthalene-based, or polycarboxylic acid-based polymers is added to a polymer emulsion at 100 ° C. in an amount of 1 to 10% based on the above polymer, and the mixture is added to cement mortar or concrete in an amount of 3 to 5%.
A method of curing underwater curing of cement mixed with a polymer emulsion using a reactive surfactant, wherein the curing is carried out in water at a temperature range of 50 ° C. or less by mixing 0%. 2. The method according to claim 1, wherein the cement is a jet cement, an early-strength cement, an ultra-high-strength cement, an alumina cement, a blast furnace cement, or a fly ash cement. 3. The curing in water of a polymer emulsion-mixed cement according to claim 1, wherein a nonionic surfactant is added to the polymer emulsion obtained by the emulsion polymerization in an amount of 0 to 2% based on the solid content of the polymer. Method.