JPH05310458A - Cement dispersant - Google Patents

Abstract

PURPOSE: To provide a cement dispersant with which machinability and workability can be remarkably improved by mixing the cement dispersant with a cement component such as cement mortar or concrete and preventing the reduction (slump loss) of its fluidity with the lapse of time.

CONSTITUTION: This cement dispersant is mainly composed of the copolymer of an alkenyl ether and maleic anhydride represented by a general formula with the molar ratio of 30-70:70-30 and a hydrolytic product thereof or the salt of the hydrolytic product. The formula is R₁O (AO)_nR₂ [AO represents the mixture of one or two kinds or more of 2-18C oxyalkylene groups and can be added in the block or random state in the case of more than two kinds, R₁ represents a 2-5C alkenyl group, R₂ is a 1-4C alkyl group and (n) represents the oxyalkylene groups to the mean additional molar number of 60 to 95.

COPYRIGHT: (C)1993,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dispersant for cement or a cement mixture, and more specifically, it is added to a cement composition such as cement mortar or concrete to reduce its fluidity with time (hereinafter referred to as slump loss and The present invention relates to a cement dispersant capable of significantly improving the workability and workability by preventing the call.

[0002]

2. Description of the Related Art A technique of using a copolymer of alkenyl ether and maleic anhydride or a derivative thereof as an additive for cement is known in JP-A-63-285140 and JP-A-2-163108. However, in these publications, it is shown that the slump loss is improved by using this copolymer.

[0003]

[Problems to be Solved by the Invention] Slump loss is the largest problem in the concrete industry, and many researchers have tried various methods to solve this problem, but no sufficient solution has been found yet. . Therefore, there is a strong desire for early resolution of this problem.

[0004]

[Means and Actions for Solving Problems] The inventors of the present invention have made earnest studies to solve the above problems, and as a result, disclosed in JP-A-63-285140 and JP-A-2-1631.
The inventors have found that a copolymer having a specific molecular structure is remarkably effective in preventing slump loss in the technology disclosed in Japanese Patent Publication No. 08, etc., and completed the present invention.

That is, the cement dispersant of the present invention has the following general formula (I) R ₁ O (AO) _n R ₂ (I) [where AO is an oxyalkylene having 2 to 18 carbon atoms] One or a mixture of two or more groups may be added blockwise or randomly in the case of two or more, and 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 oxyalkylene groups of 60 to 95. ] A copolymer of alkenyl ether and maleic anhydride represented by the formula (1) having a molar ratio of 30 to 70:70 to 30, a hydrolyzate or a salt of the hydrolyzate as a main component. It is characterized by

The cement dispersant of the present invention is significantly superior to conventional cement dispersants in reducing slump loss, is low in setting retardation, and has no adverse effect on the strength after curing. .

In the general formula (I), the alkenyl group having 2 to 5 carbon atoms represented by R ₁ is vinyl group, allyl group, metal group, 1,1-dimethyl-2-propenyl group, 3-methyl group. Although there is a -3-butenyl group and the like, a versatile allyl group is most preferable.

Examples of the oxyalkylene group having 2 to 18 carbon atoms represented by AO include 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.

Examples of the alkyl group having 1 to 4 carbon atoms represented by R ₂ include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group and tert-butyl group. When the carbon number is 5 or more, the amount of air entrained in the mortar or the concrete composition increases, and therefore when a low air amount is required, it is preferable to select an alkyl group having 1 to 4 carbon atoms.

When used alone, the copolymer having an average number of moles n of oxyalkylene groups added of 1 to 40, when used alone, is a naphthalenesulfonic acid formaldehyde highly condensate type cement dispersant and a sulfonated melamine resin type cement. While it is a cement dispersant showing almost the same properties as conventional cement dispersants such as dispersants, lignin sulfonic acid type cement dispersants, polycarboxylic acid type cement dispersants, etc., the average number of moles of oxyalkylene groups added The copolymer having n of 100 or more has an effect of significantly increasing slump with time. In particular, the larger the value of n, the greater the effect. Therefore, when this copolymer is used alone, there is a risk of causing material separation with a marked increase in fluidity of the cement composition over time.

However, the copolymer having an average addition mole number n of oxyalkylene groups of 60 to 95 is more than 100 with the copolymer having an average addition mole number n of oxyalkylene groups of 1 to 40. It is a well-balanced cement dispersant having both properties of a certain copolymer.

The cement dispersant of the present invention has a high dispersion ability and a slump loss reducing ability, and further has a low set retardation property. Therefore, it can be used alone to obtain a sufficiently high effect. However, depending on the type of cement or aggregate, and the composition of the composition thereof, the average number of moles of oxyalkylene groups added to 100 parts by weight of the copolymer having an average number of moles n of oxyalkylene groups of 60 to 95. It is also possible to add 5 to 30 parts by weight of the copolymer having n of 1 to 40, or the copolymer having an average addition mole number n of oxyalkylene groups of 100 or more, preferably 100 to 150. it can.

Further, the cement dispersant of the present invention is another known cement admixture such as an air entraining agent, a waterproofing agent,
It may be used in combination with a strength enhancer, a curing accelerator, etc., and may further contain an antifoaming agent, if necessary.

The reason why the cement dispersant of the present invention exhibits excellent slump retention is not yet clear, but it is presumed as follows.

That is, the cement dispersant of the present invention enhances the dispersibility of cement particles in the same manner as the conventional cement dispersants, and at the same time, hydrates around the polyoxyalkylene groups extending from the copolymer adsorbed on the cement particles. A layer is formed, and the steric hindrance associated therewith maintains the dispersibility of the cement particles for a long time. 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 general formula (I) and maleic anhydride using a peroxide catalyst. The molar ratio of the copolymer is selected from 30 to 70:70 to 30, preferably 50:50. At that time, other copolymerizable components such as styrene, α-olefin, vinyl acetate, etc. are mixed up to 30% by weight of the total amount of the monomers at the time of producing the copolymer, and copolymerized. May be. The copolymer may be an anhydride, a hydrolyzate, or a salt thereof.

The hydrolyzate of the copolymer is obtained by hydrolyzing the copolymerized maleic anhydride unit into a maleic acid unit.

The salt of the hydrolyzate of the copolymer is a salt formed by the maleic acid unit, and includes alkali metal salts such as lithium salt, sodium salt, potassium salt, magnesium salt, calcium salt and alkaline earth salts. In addition to metal salts, there are ammonium salts and organic amine salts.

The amount of the cement dispersant used in 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 blending amount is too small, the expected effect cannot be obtained, and if the blending amount is too large, material separation or delay of setting may occur, which is not preferable.

The cement dispersant of the present invention is not limited to ordinary Portland cement, early-hardening cement, ultra-fast-hardening cement, blast furnace cement, moderate heat cement, fly ash cement, sulfate resistant cement, and other cements, and cements such as gypsum. It can also be used for hydraulic materials.

The cement dispersant of the present invention may be used by any method such as a method of mixing it with kneading water and a method of adding it into already kneaded concrete.

[0022]

EFFECTS OF THE INVENTION The cement dispersant of the present invention exhibits high fluidity without significantly delaying the setting of cement compositions such as mortar and concrete, and has excellent slump retention properties. It is possible to significantly improve workability in construction-related construction work.

Therefore, the cement dispersant of the present invention can be applied to various uses, such as a fluidizing agent for ready-mixed concrete and a high performance AE water reducing agent, or a high performance water reducing agent for the production of secondary concrete products. Can be effectively used 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.

[0025]

【Example】

(Production of Copolymer) Based on the method disclosed in JP-A-1-297411, 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 is prepared. It was manufactured by the following method.

[0026]

[Production Example 1] Production of copolymer (a) 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 heated to 90 to 100 ° C under a nitrogen atmosphere. A copolymerization reaction was performed by heating and stirring for 3 hours.

Alkenyl ether: CH ₂ = CHCH 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 reduced pressure of about 10 mmHg to obtain a copolymer which was a brown solid at room temperature.

[0028]

[Production Example 2] Production of copolymer (b) 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 heated to 90 to 100 ° C under a nitrogen atmosphere. A copolymerization reaction was performed by heating and stirring for 3 hours.

Alkenyl ether: CH ₂ = CHCH 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 reduced pressure of about 10 mmHg to obtain a copolymer which was a brown solid at room temperature.

[0030]

[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 heated to 80 to 90 ° C under a nitrogen atmosphere. A copolymerization reaction was performed by heating and stirring for 7 hours.

Alkenyl ether: CH ₂ = CHCH 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 reduced pressure of about 10 mmHg to obtain a copolymer which was a brown viscous liquid.

[0032]

[Production Example 4] Production of copolymer (d) 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 heated to 80 to 90 ° C under a nitrogen atmosphere. A copolymerization reaction was performed by heating and stirring for 7 hours.

Alkenyl ether: CH ₂ = CHCH 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 the completion of the reaction, under reduced pressure of about 10 mmHg. Then, toluene was distilled off at 110 ° C. to obtain a copolymer which was a brown solid at room temperature.

[0034]

[Production Example 5] Production of copolymer (e) 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 heated to 80 to 90 ° C under a nitrogen atmosphere. A copolymerization reaction was performed by heating and stirring for 7 hours.

Alkenyl ether: 1644.0 g CH ₂ = CHCH 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.

[0036]

[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 heated to 75 to 85 ° C under a nitrogen atmosphere. A copolymerization reaction was performed by heating and stirring for 7 hours.

Alkenyl ether: 1864.0 g CH ₂ = CHCH ₂ O (C ₃ H ₆ O) ₆ (C ₂ H ₄ O) ₁₂ CH ₃ (block 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 yellow viscous liquid copolymer.

[0038]

[Production Example 7] Production of copolymer (g) 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 heated to 90 to 100 ° C under a nitrogen atmosphere. A copolymerization reaction was performed by heating 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. Then, toluene was distilled off at 110 ° C. to obtain a copolymer which was a brown solid at room temperature.

The number average molecular weight of the produced copolymer is shown in Table 1.
Shown in.

[0041]

[Table 1]

[0042]

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 the predetermined cement admixture shown in Table 3 were charged, and
Mix for 0 seconds, slump 18 cm, air charge 4 ~
A fluidized concrete of 5% (using Denka Grace's air entraining agent AE-140D to obtain a target air amount) was prepared. After kneading, the kneaded product was discharged into a kneading boat, kneaded for a predetermined number of times, and the slump and the change in air amount with time were measured every 30 minutes until after 60 minutes.

The methods for measuring the slump, the amount of air, the setting time and the compressive strength, and the method for preparing the test piece for compressive strength were all in accordance with Japanese Industrial Standards (JIS-A6204). The results are shown in Table 4.

[0044]

[Comparative Examples 1 to 7] The same operations as in Examples 1 to 4 were performed to prepare fluidized concrete for comparison. The results are shown in Table 4.
Shown in.

[0045]

[Table 2]

[Table 3]

[Table 4]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical display location C08F 299/02 MRS 7442-4J C08L 35/00 LHS 7921-4J (72) Inventor Hideo Oyada Kanagawa 4-2-1, Midorien, Izumi-ku, Yokohama Sunstage Midorien No. 2, 105 (72) Inventor Susumu Honda 4-7-9 Minamiyukitani, Ota-ku, Tokyo

Claims (1)

[Claims] 1. A copolymer of an alkenyl ether represented by the general formula (I) and maleic anhydride, the molar ratio of which is 3: 1.
A cement dispersant comprising a copolymer 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, it is added in a block 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 oxyalkylene groups of 60. ~ 95. ]