JP3226125B2 - Cement dispersant - 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 placing cement mortar or concrete on a construction site and for concrete.
The present invention relates to a cement dispersant having a large water reducing effect, which is suitable for molding processing of a subsequent product or the like and can greatly reduce cement mixing water without lowering workability.

[0002]

2. Description of the Related Art In recent years, construction work has become technically sophisticated and needs for concrete performance have diversified. On the other hand, there is a situation where the quality of the aggregate is deteriorated, and the development of a high-performance cement dispersant suitable for these situations is desired. Conventionally, cement dispersants have been used for the purpose of reducing kneading water, and studies have been made for this purpose. Conventionally, various agents such as lignin sulfonate, oxycarboxylate, naphthalene sulfonate formalin condensate and melamine sulfonate formalin condensate have been used as dispersants.
However, these have limitations in their dispersing ability, have high air entrainment, and have drawbacks such as a significant decrease in strength, and are not always satisfactory.

[0003] Recently, as a polycarboxylic acid-based cement dispersant having a higher dispersing ability, for example, JP-A-4-1752
No. 54 discloses a polyether compound obtained by monoesterifying a copolymer of maleic anhydride and polyalkylene glycol allyl alkyl ether with an alkyl polyalkylene glycol, and JP-B-59-18338 discloses (meth) acrylic acid. Copolymers of (meth) acrylic acid with an ethylene oxide adduct are disclosed in JP-A-61-1.
No. 46746 discloses a copolymer of a chain olefin and an α, β-unsaturated dicarboxylic acid. However, these cement dispersants are not necessarily sufficient in dispersibility. Therefore, in order to obtain sufficient cement dispersibility, it is necessary to use many relatively expensive dispersants. Further, in the case of a chain olefin and an α, β-unsaturated dicarboxylic acid copolymer, there are disadvantages such as that the curing speed of cement is greatly reduced.

[0004]

The problem to be solved by the present invention is that, as described above, the conventional cement dispersants are still insufficient in performance such as water reducing effect, air entrainment property and cement setting speed. On the point.

[0005]

Means for Solving the Problems The present inventors have found that a copolymer of maleic anhydride and an alkyl vinyl ether, which is monoesterified with an alkyl polyalkylene glycol, exhibits excellent performance as a cement dispersant. And arrived at the present invention. That is, the present invention provides a copolymer of 30 to 70 mol% of maleic anhydride and 30 to 70 mol% of an alkyl vinyl ether represented by the following general formula (I), A cement dispersant characterized by being an alkyl polyalkylene glycol ester of an alkyl vinyl ether-maleic anhydride copolymer obtained by esterification with 1 to 50% by glycol. General formula (I)

Embedded image CH ₂ ＣＨCHOR (wherein R is an alkyl group having 1 to 4 carbon atoms) General formula (II)

Embedded image wherein R is an alkylene group having 2 to 4 carbon atoms;
R ′ is an alkyl group having 1 to 4 carbon atoms, and m is 2 to 2
It is an integer of 5. )

The maleic anhydride used in the present invention includes:
It may contain maleic anhydride derivatives and other α, β-unsaturated carboxylic acids such as citraconic anhydride, itaconic anhydride and the like.

Specific examples of the alkyl vinyl ether used in the present invention include methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, and one or more of these. May be used. And, the carbon number of the alkyl group of this alkyl vinyl ether is preferably 4 or less, and when it is 5 or more, the air entrainment is increased and the strength of the concrete may be reduced. Further, among alkyl vinyl ethers having 4 or less carbon atoms in the alkyl group,
Methyl vinyl ether, which is water-soluble and has excellent cement dispersibility, is more preferable.

In the method for producing the copolymer used in the present invention, known polymerization means and polymer reaction means can be arbitrarily applied. Here, the charging ratio of (maleic anhydride) / (alkyl vinyl ether) is (30-70) / (70-30).
(Molar ratio), but an equimolar mixture is particularly preferred. In addition, the polymerization operation uses a radical catalyst such as benzoyl peroxide, azobisisobutyronitrile, and usually, benzene, toluene, benzene derivatives such as ethylbenzene, ethyl acetate, organic acid esters such as isopropyl acetate, methyl ethyl ketone, In a solvent such as a ketone such as methyl isobutyl ketone, an organic halide such as carbon tetrachloride or chloroform, etc.
Radical copolymerization is performed at ~ 150 ° C. However, in order to use the copolymer as a cement dispersant, the copolymer must have a weight-average molecular weight of 100,000 or less. However, ordinary chain transfer agents such as thiol-based chain transfer agents and alkylaldehyde-based chain transfer agents Agents and the like can be used. Further, a chain transfer agent such as an alkyl aldehyde can be used as the solvent. Further, as a technique for suppressing the molecular weight, a method in which maleic anhydride and a radical catalyst are added to a solvent, and an alkyl vinyl ether is dispensed and supplied over a specific period of time is also used. In addition, monomers such as styrene and α-olefin can also be copolymerized as long as the properties of the obtained copolymer are not changed.

The copolymer of maleic anhydride and alkyl vinyl ether of the present invention can be used as it is as an effective component of a cement dispersant, and is further esterified with an alkyl polyalkylene glycol to form long chain side groups. By using the introduced ester, higher water-reducing performance can be obtained.

The method for producing the ester compound of the present invention includes:
Known esterification means can be arbitrarily applied. For example, a copolymer of alkyl vinyl ether and maleic anhydride and an alkyl polyalkylene glycol, benzene, toluene, benzene derivatives such as ethylbenzene, ethyl acetate,
Organic solvents such as isopropyl acetate, ketones such as methyl ethyl ketone and methyl isobutyl ketone, or alkyl polyalkylene glycol itself used for esterification can be used as a solvent. Also,
The solvent used as the polymerization solvent can be used as it is as the esterification reaction solvent, and in this case, a continuous process becomes possible. The reaction temperature of the esterification reaction is usually 50 to 1
50 ° C. As the esterification catalyst, for example, an acid catalyst such as sulfuric acid and P-toluenesulfonic acid, and a tertiary amine such as triethylamine and triethanolamine can be used. The degree of esterification can be easily changed to a diester by adjusting the reaction time, reaction temperature, type and amount of catalyst, and the like.

The alkylpolyalkylene glycol in the present invention includes an ethylene oxide (EO) and / or propylene oxide (PO) adduct of an alcohol having 4 or less carbon atoms. The EO and / or PO addition mole number of the alkylene oxide is used in the range of 2 to 25 moles. If the number of moles of EO and / or PO added to the alkylene oxide exceeds 25, a large amount of air is entrained in the concrete, which is not preferable. When the number of carbon atoms of the terminal alkyl group of the alkyl polyalkylene glycol is 5 or more, the amount of air entrained similarly increases, which is not preferable.

The esterification of the maleic anhydride group with an alkylpolyalkylene glycol can be arbitrarily changed up to a diester (degree of esterification: 100%). And preferably in the range of 5 to 40%. When the degree of esterification exceeds 50%, not only does the water-reducing performance decrease as a cement dispersant, but it is economically disadvantageous. On the other hand, if the degree of esterification is 1% or less, sufficient water reducing performance cannot be obtained.

The preferred molecular weight of the alkyl polyalkylene glycol ester of the copolymer of maleic anhydride and alkyl vinyl ether in the present invention can be appropriately determined depending on the mixing conditions and the like actually used as a cement dispersant. The measured weight average molecular weight is 3,000 to 100,000 in terms of polyethylene glycol.
It is preferred that In addition, as long as the effects of the present invention are not substantially impaired, a part of the maleic anhydride group may be esterified with a lower alcohol and amidated or imidized for use.

The thus obtained alkyl polyalkylene glycol ester of a copolymer of maleic anhydride and an alkyl vinyl ether (hereinafter referred to as an ester) can be used as it is as an active ingredient of a cement dispersant. Some or all of the carboxyl groups can be used in the form of a salt depending on the above. Examples of the ionic portion forming these salts include alkali metal ions such as lithium, sodium and potassium, alkaline earth metal ions such as calcium and magnesium, trivalent metal ions such as aluminum and iron, ammonium, ethanolamine, dimethylamine, and the like. Examples include ions from organic amines such as triethylamine and triethanolamine.

The ester of the present invention can be used as it is as a cement dispersant. Further, it can be used in combination with other known cement admixtures containing an ester as a main component. As such known cement admixtures,
For example, conventional cement dispersing agents, air entraining agents, cement wetting and dispersing agents, strength enhancers, hardening accelerators and the like can be mentioned.

The cement dispersant of the present invention can be used for hydraulic cements such as Portland cement, alumina cement and various mixed cements, or hydraulic materials other than cements such as gypsum. As a method of using the cement dispersant of the present invention, for example, after dissolving in kneading water, a method of adding simultaneously with the kneading water when preparing the cement composition,
Alternatively, any method such as a method of adding to a cement composition already kneaded can be adopted. This is usually added in the form of an aqueous solution, but can also be added in the form of a powder.

The amount of the cement dispersant of the present invention used is 0.0
1 to 2.5% by weight is good. If it is less than 0.01% by weight, sufficient slump loss prevention performance may not be obtained.
If the content exceeds 2.5% by weight, it may be economically disadvantageous or cause problems such as retardation of setting and material separation of the cement composition.

The cement dispersant of the present invention exhibits high fluidity without causing a large retardation of setting to cement compositions such as cement mortar and concrete, and has excellent slump loss prevention performance. Therefore, workability is significantly improved in mortar work and concrete work. Therefore, the cement dispersant of the present invention can be effectively used as a fluidizing agent for concrete including, for example, ready-mixed concrete. The production of ready-mixed concrete can be easily realized. Further, it can be effectively used as a high-performance water reducing agent for concrete secondary products.

[0019]

The present invention will be described in more detail with reference to the following examples.

Copolymerization Example Using a 1.5 liter glass autoclave equipped with a stirrer, the reaction was carried out with the air shut off.
A vacuum conduit and a nitrogen conduit were connected. The polymerization vessel was heated on a water bath. First, 50.4 g of maleic anhydride was charged, the autoclave was closed, and after vacuum substitution, nitrogen was introduced to return to normal pressure. Next, 370 g of n-butyraldehyde and 35.8 g of methyl vinyl ether were added, and the mixture was stirred for about 15 minutes until maleic anhydride was dissolved. The mixture is heated to 70 DEG C. and an initiator solution consisting of 1 g of lauroyl peroxide and 100 g of n-butyraldehyde is added.
Then, the mixture was reacted for 8 hours to complete the polymerization. The weight average molecular weight of the obtained copolymer was 6,200 as a result of GPC analysis (eluent: aqueous sodium chloride solution, in terms of polyethylene oxide). This is called copolymer-1
And

Esterification Example A 1 liter glass autoclave equipped with a stirrer and reflux condenser was used and a nitrogen line was connected so that the reaction could be carried out with the air shut off. The heating of the reaction vessel was performed on a water bath. First, methyl ethyl ketone 240
g, 35 g of the copolymer-1 produced in the copolymerization example was charged into a reactor, and the inside of the reactor was replaced with nitrogen to dissolve the copolymer. Then, methoxypolyethylene glycol (approximately 10 moles of ethylene oxide added: UNIOX M- manufactured by NOF Corporation)
400) 27 g and sulfuric acid 2 g as a catalyst were charged, and the mixture was heated to 80 ° C. and reacted for 12 hours to complete the esterification of methoxypolyethylene glycol. The weight average molecular weight of the obtained ester was 9,800 as a result of GPC analysis (eluent: aqueous sodium chloride solution, in terms of polyethylene glycol), and the degree of esterification was 15
%Met. This is designated as polymer No. 1.

Thereafter, polymerization and esterification are carried out in accordance with the method of the above-mentioned copolymer example and esterification example, and alkyl vinyl ether, alkyl polyalkylene glycol,
Samples having different degrees of esterification and molecular weights (Polymer Nos. 2 to 6) were prepared. Table 1 shows the results.

[0023]

[Table 1]

Aqueous cement dispersant solution The obtained ester was dissolved in water and neutralized with NaOH to obtain an aqueous solution having a pH of 7 and a concentration of 15% by weight, which was used in a mortar test.

Examples and Comparative Examples Materials Used and Test Methods Cement: Equal amounts of ordinary Portland cement of Asano Cement / Sumitomo Cement / Denka Cement Fine aggregate: River sand Water: Tap water Water / cement ratio: 45/55 Weight ratio Cement / fine aggregate ratio: 1/2 For the above formulation, the polymer N of the present invention was used as an example as an example.
O. 1 to 6 were added and kneaded, and the resulting mortar composition was subjected to a mortar test using a mini slump flow or the like. In addition, as a comparative example, when no dispersant was added, a copolymer before esterification or a mortar obtained by adding and kneading a commercially available product was also tested by the above-described test method. The test results are shown in Table 2. From this result, the alkyl polyalkylene glycol ester of the alkyl vinyl ether-maleic anhydride copolymer of the present invention is:
It can be seen from the slump value that a good water reducing effect is obtained, and that the curing speed is high from the compressive strength.

[0026]

[Table 2]

[0027]

As described above, the alkyl polyalkylene glycol ester of the alkyl vinyl ether-maleic anhydride copolymer of the present invention has a large water reducing effect and a high curing speed, and is excellent as a cement dispersant.

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI C08L 35/00 C08L 35/00 (56) References JP-A-63-11557 (JP, A) JP-A-4-175254 (JP) (A) JP-A-5-70654 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 24/26 B01F 17/52 C08F 216/20 C08F 222/06 C08L 35/00

Claims (2)

(57) [Claims] 1. A method according to claim 1, wherein 30 to 70 mol% of maleic anhydride and 30 to 70 mol% of an alkyl vinyl ether represented by the following general formula (I)
70 mol% of the copolymer is treated with an alkylpolyalkylene glycol represented by the following general formula (II) to form
% Alkyl vinyl ether obtained by esterification
A cement dispersant, which is an alkyl polyalkylene glycol ester of a maleic anhydride copolymer. General formula (I) CH ₂ ＣＨCHOR (wherein R is an alkyl group having 1 to 4 carbon atoms) General formula (II) R′O (AO) m H (Formula 1) Wherein A is an alkylene group having 2 to 4 carbon atoms,
R ′ is an alkyl group having 1 to 4 carbon atoms, and m is 2 to 2
It is an integer of 5. ) 2. An alkyl polyalkylene glycol ester of an alkyl vinyl ether-maleic anhydride copolymer comprising a water-soluble polymer compound having a weight average molecular weight of 3,000 to 100,000 in terms of polyethylene glycol. The cement dispersant according to claim 1.