Additive including cross-linked polycarboxylic copolymer and cement composition comprising the same

Abstract

Disclosed are an additive of a cement composition including a cross-linked polycarboxylic copolymer and a cement composition including the same. More particularly, an additive of a cement composition including a polycarboxylic copolymer and/or a salt thereof, wherein the polycarboxylic copolymer is a copolymer of a monomer mixture including an alkoxy polyalkylene glycol mono(meth)acrylic acid ester-based monomer, a (meth)acrylic acid-based monomer, and a cross-linking agent containing 5 to 20 alkylene oxide groups and having two or more acrylate groups or vinyl groups, and a cement composition including the same are disclosed. The additive of the cement composition including the polycarboxylic copolymer according to the present invention controls a cross-linked structure and thereby initial sensitivity and retentivity are improved, and, accordingly, a cement composition having superior long-term workability may be formed.

Claims

1. An additive of a cement composition comprising a polycarboxylic copolymer and/or a salt thereof, wherein the polycarboxylic copolymer is a copolymer of a monomer mixture comprising an alkoxy polyalkylene glycol mono(meth)acrylic acid ester-based monomer, a (meth)acrylic acid-based monomer, a cross-linking agent containing 5 to 20 alkylene oxide groups and having two or more acrylate groups or vinyl groups, and a polyoxyalkylene alkenyl ether sulfate salt, and wherein the additive has a weight average molecular weight of 30,000 to 70,000.

2. The additive according to claim 1, wherein the salt of the polycarboxylic copolymer is a copolymer salt obtained by neutralizing the polycarboxylic copolymer with an alkaline material.

3. The additive according to claim 2, wherein the alkaline material is at least one selected from the group consisting of hydroxides, chlorides and carbonates of monovalent or divalent metals, ammonia, and organic amines.

4. The additive according to claim 1, wherein the polycarboxylic copolymer is a copolymer of a monomer mixture comprising 50 to 97.5 wt % of an alkoxy polyalkylene glycol mono(meth)acrylic acid ester-based monomer, 1 to 48.5 wt % of a (meth)acrylic acid-based monomer, and 0.1 to 10 wt % of a cross-linking agent containing 5 to 20 alkylene oxide groups and having two or more acrylate groups or vinyl groups, based on the total weight of the polycarboxylic copolymer.

5. The additive according to claim 1, wherein the polyoxyalkylene alkenyl ether sulfate salt is comprised in an amount of 1 to 48 wt %, based on total weight of the polycarboxylic copolymer.

6. The additive according to claim 1, wherein the alkoxy polyalkylene glycol mono(meth)acrylic acid ester-based monomer is represented by Formula 1 below: ##STR00003## wherein R.sup.1 is a hydrogen atom or a methyl group; R.sup.2O is C.sub.2-C.sub.4 oxyalkylene or a mixture of at least two kinds thereof; R.sup.3 is C.sub.1-C.sub.4 alkyl; and m denotes an average addition mole number of the oxyalkylene group and is an integer of 50 to 200.

7. The additive according to claim 6, wherein the R.sup.2O group comprises a combination of at least two kinds of C.sub.2-C.sub.4 oxyalkylenes and is present in a block or random form.

8. The additive according to claim 6, wherein the alkoxy polyalkylene glycol mono(meth)acrylic acid ester-based monomer is at least one monomer selected from the group consisting of methoxy polyethylene glycol mono(meth)acrylate, methoxy polypropylene glycol mono(meth)acrylate, methoxy polybutylene glycol mono(meth)acrylate, methoxy polyethylene glycol polypropylene glycol mono(meth)acrylate, methoxy polyethylene glycol polybutylene glycol mono(meth)acrylate, methoxy polypropylene glycol polybutylene glycol mono(meth)acrylate, methoxy polyethylene glycol polypropylene glycol polybutylene glycol mono(meth)acrylate, ethoxy polyethylene glycol mono(meth)acrylate, ethoxy polypropylene glycol mono(meth)acrylate, ethoxy polybutylene glycol mono(meth)acrylate, ethoxy polyethylene glycol polypropylene glycol mono(meth)acrylate, ethoxy polyethylene glycol polybutylene glycol mono(meth)acrylate, ethoxy polypropylene glycol polybutylene glycol mono(meth)acrylate, and ethoxy polyethylene glycol polypropylene glycol polybutylene glycol mono(meth)acrylate.

9. The additive according to claim 1, wherein the (meth)acrylic acid-based monomer is represented by Formula 2 below:
R.sup.4COOM.sup.1(2) wherein R.sup.4 is a C.sub.2-C.sub.3 hydrocarbon group containing an unsaturated bond; and M.sup.1 is a hydrogen atom, a monovalent or divalent metal, an ammonium group, or an organic amine salt.

10. The additive according to claim 9, wherein the (meth)acrylic acid-based monomer represented by Formula 2 is at least one monomer selected from the group consisting of acrylic acid, methacrylic acid, and monovalent or divalent metal salts, ammonium salts and organic amine salts of these acids.

11. The additive according to claim 1, wherein the polyoxyalkylenealkenyl ether sulfate salt is represented by Formula 3 below: ##STR00004## wherein R.sup.5 is a hydrogen atom or a methyl group; R.sup.6 is C.sub.1-C.sub.3 alkylene, phenylene or alkylphenylene; R.sup.7O is C.sub.1-C.sub.4 oxyalkylene or a mixture of at least two kinds thereof; n denotes an average addition mole number of the oxyalkylene group and is an integer of 10 to 50; and M.sup.2 is a hydrogen atom, a monovalent metal, ammonium, or an organic amine.

12. The additive according to claim 11, wherein the R.sup.7O group comprises a combination of at least two kinds of C.sub.1-C.sub.4 oxyalkylenes and is present in a block or random form.

13. The additive according to claim 11, wherein the polyoxyalkylene alkenyl ether sulfate salt is at least one monomer selected from the group consisting of: sulfoxypolyethylene glycol nonylphenylpropenyl ether, sulfoxypolyethylene glycol allyl ether, sulfoxypolypropylene glycol allyl ether, sulfoxypolybutylene glycol allyl ether, sulfoxypolyethylene glycol 2-butenyl ether, sulfoxypolypropylene glycol 2-butenyl ether, sulfoxypolybutylene glycol 2-butenyl ether, sulfoxypolyethylene glycol 3-butenyl ether, sulfoxypolypropylene glycol 3-butenyl ether, sulfoxypolybutylene glycol 3-butenyl ether, sulfoxypolyethylene glycol 3-pentenyl ether, sulfoxypolypropylene glycol 3-pentenyl ether, sulfoxypolybutylene glycol 3-pentenyl ether, sulfoxypolyethylene glycol (3-vinyl-5-methyl)phenyl ether, sulfoxypolypropylene glycol (3-vinyl-5-methyl)phenyl ether, sulfoxypolybutylene glycol (3-vinyl-5-methyl)phenyl ether, sulfoxypolyethylene glycol (3-vinyl-5-ethyl)phenyl ether, sulfoxypolypropylene glycol (3-vinyl-5-ethyl)phenyl ether, sulfoxypolybutylene glycol (3-vinyl-5-ethyl)phenyl ether, sulfoxypolypropylene glycol (3-propenyl-5-propyl)phenyl ether, sulfoxypolybutylene glycol (3-propenyl-5-propyl)phenyl ether, sulfoxypolyethylene glycol (3-propenyl-5-butyl)phenyl ether, sulfoxypolypropylene glycol (3-propenyl-5-butyl)phenyl ether, sulfoxypolybutylene glycol (3-propenyl-5-butyl)phenyl ether, 2 sulfoxypolyethylene glycol-3-(4-methylphenoxy)propylene allyl ether, 2-sulfoxypolypropylene glycol-3-(4-methylphenoxy)propylene allyl ether, 2-sulfoxypolybutylene glycol-3-(4-methylphenoxy)propylene allyl ether, 2-sulfoxypolyethylene glycol-3-(4-ethylphenoxy)propylene allyl ether, 2-sulfoxypolypropylene glycol-3-(4-ethylphenoxy)propylene allyl ether, and 2-sulfoxypolybutylene glycol-3-(4-ethylphenoxy)propylene allyl ether; and monomers obtained by neutralizing the above-listed compounds with a monovalent metal, a divalent metal, an ammonium salt, or an organic amine.

14. The additive according to claim 1, wherein the cross-linking agent containing 5 to 20 alkylene oxide groups and having two or more acrylate groups or vinyl groups is at least one monomer selected from the group consisting of polyethylene glycol diacrylate (PEGDA), poly propylene glycol diacrylate (PPGDA), 1,6-hexanediol ethoxylate diacrylate, 1,6-hexanediol propoxylate diacrylate, neopentyl glycol ethoxylate diacrylate, neopentyl glycol propoxylate diacrylate, trimethylolpropane ethoxylate triacrylate, trimethylolpropane propoxylate triacrylate, pentaerythritol ethoxylate triacrylate and pentaerythritol propoxylate triacrylate.

15. A cement composition comprising at least one additive selected from the group consisting of: a polycarboxylic copolymer comprising a copolymer of a monomer mixture comprising an alkoxy polyalkylene glycol mono(meth)acrylic acid ester-based monomer, a (meth)acrylic acid-based monomer, a cross-linking agent containing 5 to 20 alkylene oxide groups and having two or more acrylate groups or vinyl groups, and a polyoxyalkylene alkenyl ether sulfate salt, and a copolymer salt obtained by neutralizing the polycarboxylic copolymer using an alkaline material, wherein the additive has a weight average molecular weight of 30,000 to 70,000.

16. The cement composition according to claim 15, wherein the additive is comprised in an amount of 0.01 to 10 parts by weight based on 100 parts by weight of the cement.

17. A method of preventing reduction in fluidity of a cement composition, the method comprising: providing the cement composition according to claim 15, and continuously entraining air into the cement composition.

Description

MODE FOR INVENTION

(1) Now, the present invention will be described in more detail with reference to the following examples. These examples are provided only for illustration of the present invention and should not be construed as limiting the scope and spirit of the present invention.

Example 1

(2) 150 parts by weight of water was added to a 2 L glass reactor equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen feed tube, and a reflux cooler, nitrogen is fed into the reactor while stirring, and the reactor was heated to 80 C. under the nitrogen atmosphere.

(3) Subsequently, 20 parts by weight of a 3 wt % aqueous ammonium persulfate solution was added to the reactor and the resulting solution was completely dissolved. Thereafter, an aqueous monomer solution as a polymerization composition prepared by mixing 300 parts by weight of methoxypolyethylene glycol monomethacrylate (average addition mole number of ethylene oxide: 50 moles), 35 parts by weight of acrylic acid, 1.0 part by weight of a polyoxyethylene nonylphenylpropenyl ether sulfate ammonium salt as a non-ionic and anionic reactive surfactant (average addition mole number of ethylene oxide: 10 moles), 0.25 parts by weight of polyethylene glycol diacrylate as a cross-linking agent (average addition mole number of ethylene oxide: 5 moles), and 50 parts by weight of water, a mixed solution of 2.5 parts by weight of 2-mercaptoethanol and 30 parts by weight of water, and 70 parts by weight of a 3 wt % aqueous ammonium persulfate solution were added dropwise to the reactor over 4 hours. Then, 10 parts by weight of a 3 wt % aqueous ammonium persulfate solution was added again thereto at once. Thereafter, reaction continued for 1 hour and the temperature of the reactor was maintained at 80 C., thereby completing polymerization.

(4) After polymerization was completed, the obtained polymer was cooled to room temperature and neutralized with a 30 wt % aqueous sodium hydroxide solution for about 1 hour to prepare a 50% solid content. The weight average molecular weight of the prepared water-soluble copolymer salt was 44,000, when measured by gel permeation chromatography (GPC).

Example 2

(5) Polymerization was performed in the same manner as in Example 1, except that an aqueous monomer solution, in which 0.5 parts by weight of polyethylene glycol diacrylate (average addition mole number of ethylene oxide: 5 moles), as a cross-linking agent, was mixed, was used in the polymerization composition of Example 1. The weight average molecular weight of the prepared water-soluble copolymer salt was 45,000, when measured by gel permeation chromatography (GPC).

Example 3

(6) Polymerization was performed in the same manner as in Example 1, except that an aqueous monomer solution, in which 0.25 parts by weight of polyethylene glycol diacrylate (average addition mole number of ethylene oxide: 10 moles), as a cross-linking agent, was mixed, was used in the polymerization composition of Example 1. The weight average molecular weight of the prepared water-soluble copolymer salt was 43,000, when measured by gel permeation chromatography (GPC).

Example 4

(7) Polymerization was performed in the same manner as in Example 1, except that an aqueous monomer solution, in which 0.5 parts by weight of polyethylene glycol diacrylate (average addition mole number of ethylene oxide: 10 moles), as a cross-linking agent, was mixed, was used in the polymerization composition of Example 1. The weight average molecular weight of the prepared water-soluble copolymer salt was 45,000, when measured by gel permeation chromatography (GPC).

Example 5

(8) Polymerization was performed in the same manner as in Example 1, except that an aqueous monomer solution, in which 0.25 parts by weight of polyethylene glycol diacrylate (average addition mole number of ethylene oxide: 20 moles), as a cross-linking agent, was mixed, was used in the polymerization composition of Example 1. The weight average molecular weight of the prepared water-soluble copolymer salt was 44,000, when measured by gel permeation chromatography (GPC).

Example 6

(9) Polymerization was performed in the same manner as in Example 1, except that an aqueous monomer solution, in which 0.5 parts by weight of polyethylene glycol diacrylate (average addition mole number of ethylene oxide: 20 moles), as a cross-linking agent, was mixed, was used in the polymerization composition of Example 1. The weight average molecular weight of the prepared water-soluble copolymer salt was 46,000, when measured by gel permeation chromatography (GPC).

Comparative Example 1

(10) Polymerization was performed in the same manner as in Example 1, except that an aqueous monomer solution was mixed except for a cross-linking agent, and was used in the polymerization composition of Example 1. The weight average molecular weight of the prepared water-soluble copolymer salt was 46,000, when measured by gel permeation chromatography (GPC).

Comparative Example 2

(11) Polymerization was performed in the same manner as in Example 1, except that an aqueous monomer solution, in which 0.25 parts by weight of diethylene glycol diacrylate (average addition mole number of ethylene oxide: 2 moles) as a cross-linking agent was mixed, was used in the polymerization composition of Example 1. The weight average molecular weight of the prepared water-soluble copolymer salt was 43,000, when measured by gel permeation chromatography (GPC).

Comparative Example 3

(12) Polymerization was performed in the same manner as in Example 1, except that an aqueous monomer solution, in which 0.5 parts by weight of diethylene glycol diacrylate (average addition mole number of ethylene oxide: 2 moles) as a cross-linking agent was mixed, was used in the polymerization composition of Example 1. The weight average molecular weight of the prepared water-soluble copolymer salt was 45,000, when measured by gel permeation chromatography (GPC).

(13) A type and an amount of a cross-linking agent included in the polycarboxylic copolymer salt prepared according to each of Examples 1 to 6 and Comparative Examples 1 to 3 and properties of the polycarboxylic copolymer salt are shown in Table 1 below.

(14) TABLE-US-00001 TABLE 1 Cross-linking agent Amounts No. (parts by ethylene Weight average Classification Types weight) oxides molecular weight Example 1 PEGDA 0.25 5 44,000 Example 2 PEGDA 0.5 5 45,000 Example 3 PEGDA 0.25 10 43,000 Example 4 PEGDA 0.5 10 45,000 Example 5 PEGDA 0.25 20 44,000 Example 6 PEGDA 0.5 20 46,000 Comparative 44,000 Example 1 Comparative DEGDA 0.25 2 43,000 Example 2 Comparative DEGDA 0.5 2 45,000 Example 3

Experimental Example 1

Mortar Fluidity Test

(15) 500 g of Portland cement (Ssangyong Cement), 800 g of sand, 1.0 g (solid content) of each of the prepared polycarboxylic copolymers, and 180 g of water (tap water) were mixed at medium speed in a mortar mixer for 3 minutes to prepare mortar. Each prepared mortar was filled in a hollow cone having a diameter of 60 mm and a height of 40 mm and then the cone was lifted in a vertical direction. A flow value (mm) of the mortar was determined by measuring diameters in two directions of the mortar and obtaining an average value thereof.

Experimental Example 2

Concrete Test

(16) 680 kg of Portland cement (Ssangyong Cement), 1700 kg of sand, 1850 kg of rubble, 0.2 wt % (based on the weight of cement) of each polycarboxylic copolymer, and 370 kg of water (tap water) were mixed to prepare concrete. Slump and air content of each prepared concrete were measured in accordance with Korean Industrial Standards KS F 2402 and KS F 2449.

(17) Results of Experimental Examples 1 and 2 of the cement concretes prepared using these water-soluble copolymer salts are shown in Table 2 below.

(18) TABLE-US-00002 TABLE 2 Addition Flow value amount/ (mm) of mortar Slump (cm) Air content (%) Classifi- Cement After 60 After 90 After 90 cation (wt %) Initial minutes Initial minutes Initial minutes Example 1 0.2 135 145 20.5 21.5 4 3.5 Example 2 0.2 131 143 20 21 3.5 3.5 Example 3 0.2 137 149 21 22.5 3.5 3.5 Example 4 0.2 135 146 21 22 3.5 3.5 Example 5 0.2 132 144 20.5 21.5 4 4 Example 6 0.2 130 143 20 21 4 4 Compar- 0.2 125 129 19.5 20 5 5 ative Example 1 Compar- 0.2 133 138 20 20.5 4.5 4.0 ative Example 2 Compar- 0.2 129 134 20 20.5 4.5 4.5 ative Example 3

(19) As shown in Table 2 above, the mortar prepared using each of the polycarboxylic copolymers of Examples 1 to 6 has relatively high initial dispersion force and a mortar flow value after 60 minutes, which means high fluidity retaining ability, as compared to the mortar prepared using each of the polycarboxylic copolymers of Comparative Examples 1 to 3. Even in the concrete test, the concrete prepared using the mortar prepared using each of the polycarboxylic copolymers of Examples 1 to 8 has a higher slump value after 90 minutes and a larger air content than the concrete prepared using the mortar prepared using each of the polycarboxylic copolymers of Comparative Examples 1 to 5. That is, from the results shown in Table 2 above, it can be confirmed that the polycarboxylic copolymer according to the present invention enhances dispersibility of cement particles and, even when used in a small amount, exhibits high fluidity retaining ability.

(20) Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

INDUSTRIAL APPLICABILITY

(21) As described above, according to the present invention, an alkoxy polyalkylene glycol mono(meth)acrylic acid ester-based monomer, a (meth)acrylic acid-based monomer, and a cross-linking agent including 5 to 20 alkylene oxide groups and having two or more acrylate groups or vinyl groups and/or a salt of the polycarboxylic copolymer is added to a cement composition, whereby fluidity of the cement composition is enhanced even in a high water reducing ratio range and deterioration of the cement composition over time is prevented.

(22) In addition, according to the present invention, an appropriate amount of air is continuously entrained into the cement composition and thus the cement composition may have very good workability.