JPH0848852A - Cement dispersant - Google Patents

Abstract

PURPOSE:To provide a cement dispersant which comprises a copolymer from a specific alkylene glycol vinyl ether and maleic anhydride, thus shows a large water-reducing effect, high hardening rate and excellent molding processability. CONSTITUTION:This dispersant comprises a copolymer from (A) an alkylene glycol vinyl ether of the formula (A is a 2-4C alkylene; R is H, a 1-4C alkyl; n is 5-50) and (B) maleic anhydride and/or its salt. The copolymer has a weight- average molecular weight of 3,000-100,000 calculated as polyethylene glycol and is soluble in water. The salts of the copolymer is preferably at least one selected from the salts of alkali metals, alkaline earth metals, ammonium and organic amines.

Description

Detailed Description of the Invention

[0001]

[Field of Industrial Application] The present invention is applied to the construction of concrete or cement mortar or concrete at the construction site.
The present invention relates to a cement dispersant which is suitable for molding of the next product and has a large water-reducing effect that can significantly reduce cement mixing water without lowering workability.

[0002]

2. Description of the Related Art In recent years, construction work has become more technologically sophisticated and needs for concrete performance have diversified, but on the other hand, the quality of aggregate has deteriorated.
Development of a high-performance cement dispersant suitable for these situations is desired. Conventionally, cement dispersants have been used for the purpose of reducing mixing water, and studies have also been conducted for this purpose. Various dispersants such as lignin sulfonate, oxycarboxylate, naphthalene sulfonate formalin condensate and melamine sulfonate formalin condensate have been used. However, these are not always satisfactory, because they have a limited dispersion capacity, have high air entrainment, and have the drawback of significantly reducing strength.

As a polycarboxylic acid type cement dispersant having a high dispersibility, for example, Japanese Patent Publication No. 58-38380 and Japanese Patent Laid-Open No. 59-162162 disclose maleic anhydride, maleic acid alkyl ester, maleic acid alkylene glycol ester and the like maleic acid. A copolymer composed of an acid derivative and polyethylene glycol monoallyl ether, and a copolymer of (meth) acrylic acid and an ethylene oxide adduct of (meth) acrylic acid are disclosed in JP-B-59-18338. JP-A-61-146746 discloses a copolymer of a chain olefin and an α, β-unsaturated dicarboxylic acid. However, these cement dispersants do not necessarily have sufficient dispersibility, and in order to obtain sufficient dispersibility, it is necessary to use a large amount of these dispersants, resulting in high cost. In addition, chain olefins and α, β
-Unsaturated dicarboxylic acid copolymers have drawbacks such as slowing the hardening rate of cement.

As a copolymer consisting of alkylene glycol vinyl ether and maleic anhydride, Japanese Patent Publication No.
No. -20502 discloses a copolymer of methoxytriethylene glycol vinyl ether or ethoxytriethylene glycol vinyl ether and maleic anhydride. However, this copolymer is intended for use as a thickening agent for highly ionic solutions, and there is no description of its use as a cement dispersant.
Also, JP-A-63-285140 and JP-A-2-16
No. 3108 discloses a copolymer of a polyoxyalkylene derivative and maleic anhydride or a maleic acid ester. Specific examples of the polyoxyalkylene derivative include those having an allyl ether type or metally terminated type. This is only a description of various polyether type polyoxyalkylene derivatives, and when this is used as a cement dispersant, the effect cannot be obtained unless a large amount is added. In addition, polyoxyalkylene allyl ether and maleic acid derivative are basically difficult to copolymerize, and a cement dispersant is used in ordinary radical polymerization using a radical catalyst such as a peroxide or an azo compound in a solvent or in a bulk. It is difficult to obtain a copolymer having a molecular weight that can be used as a high yield in a short time, and a dispersant having a high polymerization rate and high productivity has been desired.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to show good water reducing performance even when added in a small amount, and without adversely affecting concrete properties such as air entrainment and hardening speed.
And to develop a highly productive cement dispersant. The present inventors, as a result of diligent studies, a copolymer of polyalkylene glycol vinyl ether and maleic anhydride, is significantly superior to conventionally known copolymers of polyoxyalkylene allyl ether and maleic anhydride, etc. Therefore, the present invention has been reached.

[0006]

Means for Solving the Problems The present inventors have found that a specific alkylene glycol vinyl ether / maleic anhydride copolymer or a salt thereof exhibits good cement dispersibility and good productivity. And has reached the present invention.

That is, the present invention has the general formula CH ₂ ═CHO (AO) n R (wherein A is an alkylene group having 2 to 4 carbon atoms, R is hydrogen or an alkyl group having 1 to 4 carbon atoms). , N is 5
A cement dispersant characterized by containing a copolymer of alkylene glycol vinyl ether represented by the formula (50 is an integer of 50) and maleic anhydride and / or a salt thereof. Further, in the present invention, the weight average molecular weight of the copolymer of alkylene glycol vinyl ether and maleic anhydride is 3,000 to 10 in terms of polyethylene glycol.
The present invention relates to the above cement dispersant, which is composed of 10,000 water-soluble polymer compounds. Furthermore, the present invention provides that the salt of the copolymer of alkylene glycol vinyl ether and maleic anhydride is one or more salts selected from the group of alkali metal salts, alkaline earth metal salts, ammonium salts and organic amine salts. The present invention relates to the above cement dispersant.

The alkylene glycol vinyl ether used in the present invention is a polyalkylene glycol vinyl ether and / or an alkyl polyalkylene glycol vinyl ether. Examples of the polyalkylene glycol vinyl ether and the alkyl polyalkylene glycol vinyl ether include ethylene oxide (EO),
Examples thereof include a vinyl ether body of an alkylene oxide adduct having 2 to 4 carbon atoms such as propylene oxide (PO) and tetramethylene oxide (TMO), and a vinyl ether body of the above alkylene oxide adduct of an alcohol having 4 or less carbon atoms. Ethylene oxide (E
O). When the number of carbon atoms of the alkylene oxide exceeds 4, the water reducing performance is lowered and the desired high water reducing performance cannot be obtained, which is not preferable. The number of moles of alkylene oxide added to alkylene glycol vinyl ether is 5
Is preferably in the range of 50 to 50 mol, particularly preferably 10 to 4
It is in the range of 5 mol. When the added mole number of alkylene oxide exceeds 50, material separation of the cement composition is likely to occur and good concrete properties may not be maintained. When the number of added moles is 4 or less, the desired high water-reducing property cannot be obtained, which is not preferable.

The alkylene glycol vinyl ether used in the present invention can be produced by a known method. For example, dehydration of polyalkylene glycol and / or alkyl polyalkylene glycol, introduction of terminal vinyl group by dehydrochlorination of polyalkylene glycol monochloride and / or alkyl polyalkylene glycol monochloride, introduction of vinyl group by Reppe reaction with acetylene, etc. Is.

Known polymerization means and polymer reaction means can be arbitrarily applied to the method for producing the copolymer used in the present invention. For example, using a radical catalyst such as benzoyl peroxide, azobisisobutyronitrile, benzene,
Benzene derivatives such as toluene and ethylbenzene, organic acid esters such as ethyl acetate and isopropyl acetate, ketones such as methyl ethyl ketone and methyl isobutyl ketone,
Solution polymerization can be carried out by radical copolymerization in a solvent such as carbon tetrachloride or an organic halide such as chloroform at 5 to 150 ° C. Further, alkylene glycol vinyl ether can be converted into maleic anhydride without using a solvent. After being dissolved well, by the above-mentioned radical catalyst, 5 to 150 ° C.
It is also possible to carry out bulk polymerization with. The polymerization method to be selected is selected in consideration of the ease of handling and the cost advantage, depending on the melting point and viscosity of the alkylene glycol vinyl ether used, the molecular weight and viscosity of the resulting copolymer, and the like. do it. In the case of producing a copolymer having a weight average molecular weight of about several thousand, a usual chain transfer agent such as a thiol chain transfer agent or an alkylaldehyde chain transfer agent can be used. Further, as a technique for controlling the molecular weight, there is also used a method in which maleic anhydride and a radical catalyst are added to a solvent and alkylene glycol vinyl ether is separately added thereto over a specific period of time. It should be noted that styrene, olefins such as α-olefins, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n, etc. as long as the characteristics of the obtained copolymer are not changed.
It is also possible to copolymerize monomers such as lower alkyl vinyl ethers such as butyl vinyl ether and isobutyl vinyl ether.

The molecular weight of the copolymer of alkylene glycol vinyl ether and maleic anhydride can be appropriately determined depending on the compounding conditions actually used as a cement dispersant, but preferably the weight average molecular weight measured by GPC is equivalent to polyethylene glycol. At 3,000-100,0
00. When the molecular weight is 3,000 or less, the water-reducing performance is lowered and at the same time, the solidification of concrete or mortar is delayed. On the other hand, when the molecular weight is 100,000 or more, the water reducing performance is deteriorated, which is not preferable. Further, a part of the maleic anhydride group may be esterified with alcohols such as lower alcohols and polyalkylene glycols or amidated with amines and imidized as long as the effect of the present invention is not substantially impaired. it can.

The thus obtained copolymer of alkylene glycol vinyl ether and maleic anhydride can be used as it is as an active ingredient of a cement dispersant, but if necessary, part or all of the carboxyl groups can be converted into salts. Can be used in the form. As the ionic moiety forming these salts, 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 and ethanolamine. Examples thereof include organic amines such as dimethylamine, triethylamine, and triethanolamine, and sodium salts are particularly preferable from the economical point of view.

The copolymer of alkylene glycol vinyl ether of the present invention and maleic anhydride and / or its salt can be used as it is as a cement dispersant. Further, this copolymer may be used as a main component in combination with other known cement admixtures. Examples of such known cement admixtures include conventional cement dispersants, air entrainers, cement wetting dispersants, strength enhancers, hardening accelerators, defoamers, and separation reducers. Further, the cement dispersant of the present invention can be used for hydraulic cements such as Portland cement, alumina cement, various mixed cements, and hydraulic materials other than cements such as gypsum.

The cement dispersant of the present invention can be used, for example, by dissolving it in kneading water and then adding it together with the kneading water when preparing the cement composition, or adding it to the already kneaded cement composition. Either method can be adopted. Further, this is usually added in the form of an aqueous solution, but it may be added in the form of powder.

The cement dispersant of the present invention is characterized by exhibiting good performance even when added in a small amount, and the amount of its use is 0.01-0.5 in terms of solid content based on the cement in the cement composition. 2.5% by weight is suitable. If it is less than 0.01% by weight, sufficient slump loss prevention performance may not be obtained. On the other hand, if it exceeds 2.5% by weight, problems such as retardation of setting and material separation of the cement composition may occur, and it is economically disadvantageous.

The cement dispersant of the present invention exhibits high fluidity even when added in a small amount to cement compositions such as cement mortar and concrete, and has an excellent slump loss preventing property, while it has a large hardening property. Since there is no delay, workability is significantly improved. Therefore, for example, it can be effectively used as a fluidizing agent for concrete such as ready-mixed concrete, and in particular, ready-mixed concrete with a high water reduction ratio can be easily produced as a high-performance AE water reducing agent of the plant simultaneous addition type. It can also be effectively used as a high-performance water reducing agent for secondary concrete products.

[0017]

EXAMPLES Hereinafter, examples and comparative examples will be described in more detail. Production Example of Copolymer (1) In a glass autoclave equipped with a thermometer, a stirrer, a dropping device, and a nitrogen gas introduction tube, 102 g of methoxy polyethylene glycol vinyl ether (containing 22 ethylene oxide units per molecule on average) Charge 10 g of maleic anhydride (equal molar charge), toluene solvent 448
In g, heated to 80 ° C. under nitrogen atmosphere. 100 ml of an initiator solution consisting of a 1 wt% toluene solution of lauroyl peroxide was added to this, and a polymerization reaction was carried out for 5 hours. The polymerization rate at this time was 100%. Then, the solvent was removed by vacuum drying to obtain a waxy copolymer (1). The weight average molecular weight of this copolymer is shown in Table 1.

Production Examples of Copolymers (2) to (4) and Comparative Polymers (1) to (2) By changing the raw material composition, as in the production example of the copolymer (1),
Methoxypolyethylene glycol vinyl ether and maleic anhydride were charged and a polymerization reaction was carried out. Table 1 shows the weight average molecular weights of the methoxy polyethylene glycol vinyl ether used and the copolymer obtained.

Production Example of Comparative Polymer (3) In a glass autoclave equipped with a thermometer, a stirrer, a dropping device, and a nitrogen gas introducing tube, methoxypolyethylene glycol monoallyl ether (11 ethylene oxide units per molecule on average) was prepared. 95 g, maleic anhydride 17 g, and toluene solvent 448 g, and heated to 80 ° C. under a nitrogen atmosphere. Add 100 ml of an initiator solution consisting of a 1 wt% toluene solution of lauroyl peroxide.
It was added and a polymerization reaction was carried out for 25 hours. The polymerization rate at this time was 83%. Then, the solvent was removed by vacuum drying to obtain a liquid copolymer. The weight average molecular weight of this copolymer is shown in Table 1.

[0020]

[Table 1]

Cement Dispersant Composition The copolymer of the present invention and the comparative polymer shown in Table 1 were dissolved in water to prepare a 15 wt% aqueous solution. The pH of this aqueous solution was 2. The aqueous solution was adjusted to pH = 7 with NaOH and used for mortar test.

Examples and Comparative Examples Mortar formulation Water 270 g Cement 600 g Sand 1200 g Water reducing agent Addition rate to cement 0.18% (The addition rate is shown as a ratio of polymer solid content of the water reducing agent to cement. The amount of the aqueous solution of the agent was added so that the addition rate to cement was 0.18%.) Water / cement ratio 45/55 weight ratio sand / cement ratio 2/1 weight ratio As a cement Onoda Cement Company / Sumitomo Cement A mortar test was carried out with the above-mentioned composition using a mixture of equal amounts of ordinary Portland cements manufactured by Hamamatsu / Denki Kagaku Co., Ltd., using Himekawa-produced river sand as sand and tap water as water. After adding the water-reducing agent aqueous solution and the mortar kneading water to the mortar mixer, cement and sand were added in this order, and the obtained mortar composition was minislump flow, air entrainment amount, material age 1
Daily intensity was measured. Here, for the measurement of the mini slump flow, the inner diameter at the lower end is 100 mm, the inner diameter at the upper end is 50 mm, and the height is 15.
A 0 mm cast iron slump cone and a metal container having an inner diameter of 76 mm and a height of 88 mm were used to measure the air entrainment amount. Material age 1-day strength, cross section 40mm square, length 160m
It was measured by the compressive strength of the test piece of m. Other details are based on JIS A 6204. According to the above measuring method, the copolymer (1) of the present invention as an example-
Regarding the mortar composition in which the sodium salt of (4) and the copolymer (2) were added, as a comparative example, the sodium salt of comparative polymers (1) to (3) and a commercially available water reducing agent were added and kneaded. With respect to the mortar composition, the mini slump flow value, the material age 1-day strength, and the air entrainment amount were measured, and the results are shown in Table 2. In the examples, it is understood that the copolymer of alkylene glycol vinyl ether and maleic anhydride has a high water reducing property and does not adversely affect the mortar strength after curing. In the comparative polymer (1) of the comparative example, the number of EO-added moles was as small as 2. Therefore, the minislump flow value was small, and in the comparative polymer (2) of the comparative example, the EO-added mole number was 60. As a result, the materials were separated from each other, and the comparative polymer (3) of Comparative Example had a low minislump flow value, resulting in poor performance.

[0023]

[Table 2]

[0024]

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

Claims (3)

[Claims] 1. A compound represented by the general formula CH ₂ ═CHO (AO) n R (wherein A is an alkylene group having 2 to 4 carbon atoms, R is hydrogen or an alkyl group having 1 to 4 carbon atoms, and n is 5-
A cement dispersant characterized by containing a copolymer of alkylene glycol vinyl ether represented by the formula 50) and maleic anhydride and / or a salt thereof. 2. The weight average molecular weight of the copolymer of alkylene glycol vinyl ether and maleic anhydride is 3,000 to 100,000 in terms of polyethylene glycol.
The cement dispersant according to claim 1, which comprises the water-soluble polymer compound. 3. A salt of a copolymer of alkylene glycol vinyl ether and maleic anhydride is at least one salt selected from the group of alkali metal salts, alkaline earth metal salts, ammonium salts and organic amine salts. The cement dispersant according to claim 1 or 2, characterized in that.