JP3432538B2 - Cement dispersant - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dispersant for cement or a cement compound, and more particularly, to a dispersant for a cement composition such as cement mortar, concrete, and the like. The present invention relates to a cement dispersant capable of significantly improving workability and workability by preventing the deterioration of the properties over time (hereinafter referred to as slump loss). 2. Description of the Related Art A technique using a copolymer of alkenyl ether and maleic anhydride or a derivative thereof as an additive for cement is disclosed in JP-A-63-285140 and JP-A-2-163108. These publications show that the use of this copolymer improves slump loss. Problems to be Solved by the Invention Slump loss is the biggest problem in the concrete industry, and many researchers have tried various methods to solve this problem. Not found. Therefore, there is a strong desire for an early solution to this problem. The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have disclosed Japanese Patent Application Laid-Open Nos. 63-285140 and 2-1631.
In the technique disclosed in Japanese Patent Application Laid-open No. 08-0808, etc., it has been found that a copolymer having a specific molecular structure is remarkably effective in preventing slump loss, and the present invention has been accomplished. That is, the cement dispersant of the present invention has the following general formula (I) R ₁ O (AO) _n R ₂ ... (I) wherein AO is an oxyalkylene having 2 to 18 carbon atoms. with one or a mixture of two or more of groups, when two or more kinds also be added in a block form may also be added to the random form, R ₁ is an alkenyl group having 2 to 5 carbon atoms, R ₂ Is an alkyl group having 1 to 4 carbon atoms, and n is an average addition mole number of the oxyalkylene group, which is 60 to 95 (excluding n = 68) . A copolymer of alkenyl ether and maleic anhydride having a molar ratio of 30 to 70:70 to 30
Or a hydrolyzate thereof or a salt of the hydrolyzate thereof as a main component. [0006] The cement dispersant of the present invention is remarkably excellent in slump loss reduction, has a low setting retardation, and has no adverse effect on the strength after curing, as compared with the conventional cement dispersant. . In the general formula (I), examples of the alkenyl group having 2 to 5 carbon atoms represented by R ₁ include a vinyl group, an allyl group, a metal group, a 1,1-dimethyl-2-propenyl group and a 3-methyl Although there are -3-butenyl group and the like, a general-purpose allyl group is most preferable. The oxyalkylene group having 2 to 18 carbon atoms represented by AO includes oxyethylene group, oxypropylene group, oxybutylene group, oxytetramethylene group,
There are an oxide decylene group, an oxytetradecylene group, an oxyhexadecylene group, an oxyoctadecylene group and the like, and an oxyalkylene group having 2 to 4 carbon atoms is particularly preferable. The alkyl group having 1 to 4 carbon atoms represented by R ₂ includes a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group and a tert-butyl group. When the number of carbon atoms is 5 or more, the amount of air entrained in the mortar or concrete composition increases. Therefore, when a low amount of air is required, an alkyl group having 1 to 4 carbon atoms may be selected. When the copolymer having an average number of added moles n of the oxyalkylene group of 1 to 40 is used alone, a naphthalenesulfonic acid-formaldehyde high condensate cement dispersant, a sulfonated melamine resin cement Dispersant, lignin sulfonic acid-based cement dispersant, polydispersed cement dispersant exhibiting substantially the same properties as conventional cement dispersants such as polycarboxylic acid-based cement dispersant, while the average number of moles of oxyalkylene group added The copolymer in which n is 100 or more has an effect of significantly increasing the slump with time. In particular, the effect tends to increase as the value of n increases. Therefore, when this copolymer is used alone, there is a danger of causing material separation with a marked increase in the fluidity of the cement composition over time. However, the copolymer having an average number of added moles n of the oxyalkylene group of 60 to 95 is different from the copolymer having an average number of added moles n of the oxyalkylene group of 1 to 40 by 100 or more. It is a well-balanced cement dispersant having both properties of the copolymer. The cement dispersant of the present invention has both high dispersing ability and slump loss reducing ability, and has low setting retardation. Therefore, a sufficiently high effect is obtained when used alone. However, depending on the type of cement or aggregate, and how to mix them, the average number of moles of oxyalkylene groups added to 100 parts by weight of the copolymer in which the average number of moles of oxyalkylene groups n is 60 to 95 is 100 to 100 parts by weight. The copolymer in which n is 1 to 40, or the copolymer in which the average number of added moles n of the oxyalkylene group is 100 or more, preferably 100 to 150, may be used by adding 5 to 30 parts by weight. it can. [0013] The cement dispersant of the present invention may contain other known cement admixtures such as an air entrainer, a waterproofing agent,
It can be used in combination with a strength enhancer, a curing accelerator, and the like, and can also be used by adding an antifoaming agent as needed. The reason why the cement dispersant of the present invention exhibits excellent slump retention is not yet clear, but is presumed as follows. That is, the cement dispersant of the present invention enhances the dispersibility of cement particles in the same manner as a conventional cement dispersant, and simultaneously hydrates around the polyoxyalkylene groups extending from the copolymer adsorbed on the cement particles. A layer is formed, which keeps the dispersibility of the cement particles for a long time due to steric hindrance. Therefore, the cement dispersant of the present invention has both excellent dispersion performance and excellent slump loss prevention performance. The copolymer can be easily obtained by copolymerizing the compound of the formula (I) with maleic anhydride using a peroxide catalyst. The molar ratio of the copolymer is selected from 30 to 70:70 to 30, but is preferably 50:50. At this time, other copolymerizable components such as styrene, α-olefin, and vinyl acetate are mixed and copolymerized at most up to 30% by weight of the total amount of the monomers used in producing the copolymer. You may. Further, as the copolymer, any of an anhydride, a hydrolyzate, and a salt thereof can be used. The hydrolyzate of the copolymer is obtained by hydrolyzing the copolymerized maleic anhydride units to form maleic acid units. The salt of the hydrolyzate of the copolymer is obtained by forming a salt of the maleic acid unit, such as an alkali metal salt such as a lithium salt, a sodium salt, a potassium salt, a magnesium salt, and a calcium salt; In addition to metal salts, there are ammonium salts and organic amine salts. The use amount of the cement dispersant of the present invention is generally 0.05 to 2 parts by weight, preferably 0.1 to 0.5 parts by weight, based on 100 parts by weight of cement. If the amount is too small, the expected effect cannot be obtained, and if the amount is too large, material separation or setting delay may occur, which is not preferable. The cement dispersant of the present invention may be any of cements such as ordinary Portland cement, early-strength cement, ultra-high-strength cement, blast-furnace cement, moderate heat cement, fly ash cement, sulfate-resistant cement, and cements such as gypsum. Can also be used for hydraulic materials. The cement dispersant of the present invention may be used by mixing it with kneading water or by adding it to concrete already kneaded. The cement dispersant of the present invention exhibits high fluidity without causing significant delay in hardening of cement compositions such as mortar and concrete, and has excellent slump retention. The workability can be remarkably improved in civil engineering and construction-related works. Therefore, the cement dispersant of the present invention can be applied to various uses, and can be used as a superplasticizer or a high-performance AE water-reducing agent for ready-mixed concrete, or a high-performance water-reducing agent for producing secondary concrete products. It can be used effectively as Hereinafter, the cement dispersant of the present invention will be described in detail with reference to examples, but the present invention is not limited thereto. EXAMPLES (Production of copolymer) A copolymer having a molar ratio of 1: 1 between the compound of the general formula (I) and maleic anhydride according to the composition of the present invention was disclosed in JP-A-1-297411. In accordance with the following method. Production Example 1 Production of Copolymer (a) The following components were placed in a four-necked flask equipped with a cooling pipe, a nitrogen gas blowing pipe, a thermometer, and a stirrer, and placed under a nitrogen atmosphere at 90 to 90 ° C. The copolymerization reaction was performed by raising the temperature to 100 ° C. and stirring for 3 hours. Alkenyl ether: CH ₂ CHCHCH ₂ O (C ₂ H ₄ O) ₆₆ CH ₃ 1785.6 g maleic anhydride 61.7 g tert-butylperoxy-2-ethylhexanoate 13.0 g toluene 297.6 g After completion of the reaction, toluene was distilled off at 110 ° C. under a reduced pressure of about 10 mmHg to obtain a brown solid copolymer at room temperature. Production Example 2 Production of Copolymer (b) The following components were placed in a four-necked flask equipped with a cooling pipe, a nitrogen gas blowing pipe, a thermometer, and a stirrer, and were charged under a nitrogen atmosphere at 90 to 90%. The copolymerization reaction was performed by raising the temperature to 100 ° C. and stirring for 3 hours. Alkenyl ether: CH ₂ CHCHCH ₂ O (C ₂ H ₄ O) ₉₁ CH ₃ 800.0 g Maleic anhydride 20.2 g tert-Butylperoxy-2-ethylhexanoate 16.2 g Toluene 133.3 g After completion of the reaction, toluene was distilled off at 110 ° C. under a reduced pressure of about 10 mmHg to obtain a brown solid copolymer at room temperature. Production Example 3 Production of Copolymer (c) The following components were placed in a four-necked flask equipped with a cooling tube, a nitrogen gas blowing tube, a thermometer, and a stirrer, and charged under a nitrogen atmosphere at 80 to 80%. The copolymerization reaction was carried out by raising the temperature to 90 ° C. and stirring for 7 hours. Alkenyl ether: CH ₂ CHCHCH ₂ O (C ₂ H ₄ O) ₁₁ CH ₃ 1668.0 g Maleic anhydride 308.7 g tert-Butylperoxy-2-ethylhexanoate 16.2 g Toluene 556.0 g After completion of the reaction, toluene was distilled off at 110 ° C. under a reduced pressure of about 10 mmHg to obtain a brown viscous liquid copolymer. Production Example 4 Production of Copolymer (d) The following components were placed in a four-necked flask equipped with a cooling pipe, a nitrogen gas blowing pipe, a thermometer, and a stirrer, and charged under a nitrogen atmosphere at 80 to 80%. The copolymerization reaction was carried out by raising the temperature to 90 ° C. and stirring for 7 hours. Alkenyl ether: CH ₂ CHCHCH ₂ O (C ₂ H ₄ O) ₃₃ CH ₃ 1524.0 g Maleic anhydride 102.9 g Benzoyl peroxide 9.1 g Toluene 508.0 g After completion of the reaction, under reduced pressure of about 10 mmHg. The toluene was distilled off at 110 ° C. to obtain a copolymer which was a brown solid at room temperature. Production Example 5 Production of Copolymer (e) The following components were placed in a four-necked flask equipped with a cooling pipe, a nitrogen gas blowing pipe, a thermometer, and a stirrer, and charged under a nitrogen atmosphere at a temperature of 80 to 80%. The copolymerization reaction was carried out by raising the temperature to 90 ° C. and stirring for 7 hours. Alkenyl ether: 1644.0 g CH ₂ CHCHCH ₂ O (C ₃ H ₆ O) ₁₅ (C ₂ H ₄ O) ₁₅ C ₄ H ₉ (random adduct) Maleic anhydride 102.9 g Benzoyl peroxide 8.6 g Toluene 556.0 g After completion of the reaction, toluene was distilled off at 110 ° C. under a reduced pressure of about 10 mmHg to obtain a yellow viscous liquid copolymer. Production Example 6 Production of Copolymer (f) The following components were placed in a four-necked flask equipped with a cooling tube, a nitrogen gas blowing tube, a thermometer, and a stirrer, and were charged under a nitrogen atmosphere at 75 to 50%. The copolymerization reaction was performed by raising the temperature to 85 ° C. and stirring for 7 hours. Alkenyl ether: 1864.0 g CH ₂ CHCHCH ₂ O (C ₃ H ₆ O) ₆ (C ₂ H ₄ O) ₁₂ CH ₃ (block-like adduct) Maleic anhydride 205.8 g Azobisisobutyro Nitrile 13.0 g Toluene 621.0 g After completion of the reaction, toluene was distilled off at 110 ° C. under a reduced pressure of about 10 mmHg to obtain a copolymer as a yellow viscous liquid. Production Example 7 Production of Copolymer (g) The following components were placed in a four-necked flask equipped with a cooling pipe, a nitrogen gas blowing pipe, a thermometer, and a stirrer, and were charged under a nitrogen atmosphere at 90 to 90 ° C. The copolymerization reaction was performed by raising the temperature to 100 ° C. and stirring for 3 hours. Alkenyl ether: CH ₂ = CHCH ₂ O (C ₂ H ₄ O) ₁₁₅ CH ₃ 2566.0 g Maleic anhydride 51.5 g Benzoyl peroxide 13.0 g Toluene 427.7 g After completion of the reaction, under reduced pressure of about 10 mmHg. The toluene was distilled off at 110 ° C. to obtain a copolymer which was a brown solid at room temperature. Table 1 shows the number average molecular weight of the produced copolymer.
Shown in [Table 1] Examples 1 to 4 Based on the formulation shown in Table 2, using a 50-liter forced kneading mixer, 40 liters of concrete material and a predetermined cement admixture shown in Table 3 were added.
Mix for 0 seconds, slump 18cm, air charge 4 ~
Fluidized concrete at 5% (using Denka Grace air entrainer AE-140D to achieve target air volume) was prepared. After kneading, the mixture was discharged into a kneading boat, kneaded a predetermined number of times, and the change over time in the slump and air amount every 30 minutes until 60 minutes was measured. The methods for measuring the slump, the amount of air, the setting time and the compressive strength, and the method for preparing the test specimen for compressive strength were all based on Japanese Industrial Standards (JIS-A6204). Table 4 shows the results. Comparative Examples 1 to 7 The same operation as in Examples 1 to 4 was performed to prepare a fluidized concrete for comparison. Table 4 shows the results.
Shown in [Table 2] [Table 3] [Table 4]

Continuation of the front page (51) Int.Cl. ⁷ Identification code FI C08L 35/00 C08L 35/00 (72) Inventor Hideo Koyata 4-2-1 Midorien, Izumi-ku, Yokohama-shi, Kanagawa Prefecture Sunstage Midorienshi No.2 Building 105 ( 72) Inventor Susumu Honda 4-7-9 Minamiyukiya, Ota-ku, Tokyo (56) References JP-A-63-285140 (JP, A) JP-A-5-43288 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C04B 24/26

Claims (1)

(57) [Claim 1] A copolymer of an alkenyl ether represented by the general formula (I) and maleic anhydride, the molar ratio of which is 3
A cement dispersant comprising a copolymer having a ratio of 0 to 70: 70 to 30, a hydrolyzate thereof, or a salt of the hydrolyzate as a main component. R ₁ O (AO) _n R ₂ (I) wherein AO is one or a mixture of two or more oxyalkylene groups having 2 to 18 carbon atoms, and when two or more are added, they are added in a block form. R ₁ may be an alkenyl group having 2 to 5 carbon atoms, R ₂ may be an alkyl group having 1 to 4 carbon atoms, and n may be an average number of moles of the added oxyalkylene group of 60. ９５95 (excluding n = 68) . ]