JP2000247704A - Antifoaming agent for cement composition - Google Patents

Abstract

(57) Abstract: A cement composition comprising a salt of an organic amine having an unsubstituted or hydroxyl- or halogen-substituted alkyl or alkenyl group having 6 to 24 carbon atoms which may have an amide bond therebetween. Antifoaming agent. [Effect] It has an excellent defoaming effect, it can adjust the air bubbles in concrete and mortar to an appropriate amount, and it becomes possible to uniformly mix the defoamer and the aqueous solution of the admixture, which was difficult with conventional defoamers. In addition, an aqueous solution of a cement admixture that does not separate the defoamer even after long-term storage is obtained, and the addition of the defoamer becomes extremely simple.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antifoaming agent for a cement composition which can be uniformly mixed with an aqueous solution of an admixture and has an excellent antifoaming effect.

[0002]

2. Description of the Related Art Conventionally, a certain amount of air bubbles contained in concrete has been indispensable in view of improvement in durability such as freeze-thaw resistance and compressive strength. .

[0003] In recent years, requirements for cement compositions such as concrete and mortar have become more severe in order to improve quality, such as improvement in workability, improvement in deterioration of aggregate quality, and reduction in unit water volume. Various admixtures have been developed to meet the requirements.

[0004] However, it is known that the addition of these admixtures increases the amount of air entrained in concrete. If this air volume increases excessively, the compressive strength,
There is a problem that the durability such as freeze-thaw resistance is reduced, and the appearance of the resulting molded product is deteriorated due to mixing of air bubbles.

For this reason, it has been reported to add a nonionic antifoaming agent as a method for reducing the amount of air in concrete (Japanese Patent Application Laid-Open No. Hei 7-157348), but this antifoaming agent has a lipophilic property. Since it is high, there is a problem that it is separated when mixed with a hydrophilic aqueous solution of an admixture.

[0006] As described above, the conventional antifoaming agents are not sufficiently considered in terms of separation stability. For this reason, it is necessary to install a stirring device for preventing separation in the admixture tank. At present, the use of is extremely complicated.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an antifoaming agent for a cement composition having an excellent antifoaming effect which can be uniformly mixed with an aqueous solution of an admixture.

[0008]

Means for Solving the Problems and Embodiments of the Invention As a result of intensive studies to achieve the above object, the present inventor has found that it has been difficult to uniformly mix an aqueous solution of an admixture and an antifoaming agent. It has been found that an antifoaming agent for a cement composition that enables the above can be obtained.

That is, an antifoaming agent for a cement composition comprising a salt of an organic amine having an unsubstituted or hydroxyl- or halogen-substituted alkyl or alkenyl group having 6 to 24 carbon atoms which may be interposed with an amide bond is provided. A cement that has an excellent defoaming effect, can adjust air bubbles in concrete and mortar to an appropriate amount, can be uniformly mixed with an aqueous solution of an admixture, and does not cause separation of the defoaming agent even after long-term storage. An aqueous solution of an admixture was obtained, which was found to have excellent performance in that the addition of an antifoaming agent was extremely simple, and the present invention was accomplished.

The mechanism of the defoaming effect of the defoaming agent for a cement composition of the present invention is not definite, but can be inferred as follows. That is, generally, when a conventional nonionic defoaming agent and an aqueous solution of a cement admixture are mixed, the nonionic defoaming agent does not dissolve due to its high lipophilicity, and the antifoaming agent is separated over time. On the other hand, since the antifoaming agent comprising the salt of the organic amine of the present invention is water-soluble or water-dispersible, it is uniformly dissolved or dispersed in the aqueous solution of the cement admixture. When the cement admixture containing the antifoaming agent of the present invention comes into contact with the cement water, since the cement water is high-pH water containing calcium ions, the water-insoluble organic amine is finely dispersed or dispersed from the organic amine salt. Is considered to be released in an emulsified state and exhibit a very effective defoaming action.

Hereinafter, the present invention will be described in more detail.
The defoaming agent for a cement composition of the present invention comprises an unsubstituted or hydroxyl- or halogen-substituted organic amine salt having an alkyl group or an alkenyl group having 6 to 24 carbon atoms, which may have an amide bond. It is.

Here, the organic amine may be any of primary, secondary and tertiary amines. As the amine used in the present invention, those represented by the following general formula (1) can be used.

[0013]

Embedded image

In the above formula (1), R is an unsubstituted or hydroxyl- or halogen-substituted alkyl or alkenyl group having 6 to 24 carbon atoms, and R 'and R "are a hydrogen atom, unsubstituted or hydroxyl- or halogen-substituted. 1 to 24 carbon atoms
An alkyl or alkenyl group, said alkyl group or alkenyl group may be straight chain or branched chain, also _{-NHCO -, - N (CH 3} ) may be interposed amide bond CO- such . In addition, the alkyl group and the alkenyl group may be a mixed alkyl group and a mixed alkenyl group.

The number of carbon atoms of the alkyl group or alkenyl group of R (excluding the number of carbon atoms contained in the amide bond when an amide bond is present) is 6 to 24, preferably 8 to 18, more preferably 8 to 18. 10-16. When the number of carbon atoms is 5 or less, a sufficient defoaming effect cannot be obtained because of high hydrophilicity, and when the number of carbon atoms is 25 or more, since the lipophilicity is too high, when mixing with a hydrophilic admixture, May be separated. The alkyl group or alkenyl group of R ′ and R ″ has preferably 1 to 12, particularly preferably 1 to 10, carbon atoms.

Specific examples of the amine include primary amines such as hexylamine, octylamine, decylamine, dodecylamine, tetradecylamine, hexadecylamine and 2-ethylhexylamine; secondary amines such as dihexylamine and dioctylamine; Tertiary amines such as dimethylhexylamine, dimethyloctylamine, dimethyldecylamine, dimethyldodecylamine, dimethyllaurylamine, dimethyltetradecylamine, and dimethylcocoamine; laurylamidopropylamine; oleylamidoethylamine; The species can be used alone or in combination of two or more.

The amine salt is obtained by neutralizing the amine and the acid. In this case, examples of the acid used for neutralization include inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid, and organic acids such as sulfonic acid, carboxylic acid, and acidic amino acid. Specific examples of the organic acid include glycolic acid, lactic acid, glucoheptonic acid, gluconic acid, citric acid, malic acid, galactonic acid, acetic acid, tartaric acid, propionic acid, salicylic acid, succinic acid, butyric acid, pyrrolidone carboxylic acid, pyroglutamic acid, p -Toluenesulfonic acid and the like, and one of these can be used alone or in combination of two or more.

Among these, glucoheptonic acid, gluconic acid, which is used as a retarder in cement compositions,
An antifoaming agent comprising a salt of an oxycarboxylic acid such as citric acid, malic acid or galactonic acid with the above-mentioned amine has both excellent antifoaming effect and fluidity retention due to a solidification delay effect.

When the amine and the acid are neutralized to obtain an amine salt, a completely neutralized product or a partially neutralized product may be used. In the case of a partially neutralized product, a part of the acid can be in a form in which the above amine is neutralized. In this way, when a part of the acid is a salt of an organic amine, the remaining acid may be replaced with lithium as necessary. , Sodium, potassium and other alkali metal salts, calcium, magnesium, zinc and other alkaline earth metal salts, aluminum,
Trivalent metal salts such as iron, ammonium salts and the like can be used, and one of these can be used alone or in combination of two or more. Of these, alkali metal salts such as sodium and alkaline earth metal salts such as calcium are preferred.

Further, as the acid used for neutralization with the amine, an acid group-containing polymer used as a cement dispersant can also be used effectively. It is preferable in that it exhibits a cement dispersing effect in addition to the effect.

Here, examples of the acidic group-containing polymer (cement dispersant) include a water-soluble polymer having a sulfonic acid group in a molecule and a water-soluble polymer having a carboxyl group in a molecule.

Examples of the water-soluble polymer having a sulfonic acid group in the molecule include naphthalene sulfonic acid formalin condensate, polystyrene sulfonic acid, and lignin sulfonic acid.

Examples of the water-soluble polymer having a carboxyl group in the molecule include polycarboxylic acids having an alkylene oxide chain, such as polyacrylic acid and methacrylic acid / methoxypolyethylene glycol methacrylate copolymer.

In this case, as the water-soluble polymer having a carboxyl group, a copolymer obtained by copolymerizing the following (A) monomer and (B) monomer, or (A) to (C) A) and, if necessary, a copolymer obtained by copolymerizing the monomer (D) are preferably used.

(A) a monomer represented by the following general formula (2): CH ₂ ＣC (R ¹ ) COO (R ² O) _n R ³ (2) wherein R ¹ is a hydrogen atom Or a methyl group or R ² O has 2 carbon atoms.
To 4 oxyalkylene groups, n is an integer of 5 to 300, R
³ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. (B) methacrylic acid or a salt thereof, (C) a monomer represented by the following general formula (3), CH ₂ ＣC (R ⁴ ) COOR ⁵ (3) (wherein R ⁴ is a hydrogen atom Or a methyl group, R ⁵ has 1 to 1 carbon atoms
An alkyl group which may be substituted with a hydroxyl group of (5) or (R
⁶ O) _m H (where R ⁶ O represents an oxyalkylene group having 2 or 3 carbon atoms, and m represents an integer of 1 to 3). (D) Other monomers

[0026] In the monomer represented by the general formula (2), R ¹ represents a hydrogen atom or a methyl group, R ²
O is an oxyalkylene group having 2 to 4 carbon atoms, for example, -CH
_{2 CH 2 O -, - CH} 2 CH 2 CH 2 O -, - CH 2 CH (C
_{H 3) O -, - CH} 2 CH (CH 2 CH 3) O -, - CH 2
CH ₂ CH ₂ CH ₂ O— and the like. n represents the number of added moles of the oxyalkylene group, and the number of added moles (n) is preferably 5 to 300, more preferably 5 to 40, still more preferably 7 to 35, and most preferably 9 to 30.
If the number of moles added (n) is too small, the dispersing power may be insufficient, while if it is too large, the solid will have a high melting point,
Handling may be difficult.

R ³ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, such as a methyl group, an ethyl group, a propyl group and a butyl group.

Examples of the monomer (A) include polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, polybutylene glycol mono (meth) acrylate, and methoxyl in which the added mole number of the alkylene oxide is in the above range. Polyethylene glycol (meth) acrylate, methoxypolypropylene glycol (meth) acrylate, methoxypolybutylene glycol (meth) acrylate, ethoxy polyethylene glycol (meth) acrylate, ethoxypolypropylene glycol (meth) acrylate, ethoxypolybutylene glycol (meth) acrylate, propoxy Polyethylene glycol (meth) acrylate, etc., and these may be used alone or in combination of two or more. Can bet

The monomer (B) is a monomer selected from methacrylic acid and salts thereof, for example, a monovalent metal salt such as methacrylic acid or sodium, a divalent metal salt such as calcium, an ammonium salt, and an organic compound. Amine salts and the like can be mentioned, and one of these can be used alone or in combination of two or more.

The monomer (C) is represented by the following general formula (3): CH ₂ ＣC (R ⁴ ) COOR ⁵ (3), wherein R ⁴ is a hydrogen atom or a methyl group. ,
R ⁵ is represented by an alkyl group which may be substituted by a hydroxyl group having 1 to ⁵ carbon atoms or (R ⁶ O) _m H;
Examples of the alkyl group which may be substituted with a hydroxyl group include a methyl group, an ethyl group, a hydroxyethyl group,
Examples include a propyl group, a hydroxypropyl group, and a butyl group.

Further, (R ⁶ O) _m H in R ⁶ O is 2 carbon atoms
Or shows a 3 oxyalkylene group, for example -CH ₂ C
_{H 2 O -, - CH 2} CH 2 CH 2 O -, - CH (CH 3) C
H ₂ O— and the like are exemplified, and m represents the number of moles of the oxyalkylene group added, and the number of moles (m) is an integer of 1 to 3.

The monomer (C) not only enables powdering of the copolymer, but also imparts hydrophobic adsorbability to the cement particles and further improves the fluidity retention. Examples of such a monomer (C) include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, and (meth) acrylic acid. 2-hydroxypropyl acid, diethylene glycol mono (meth) acrylate, dipropylene glycol mono (meth) acrylate, triethylene glycol mono (meth) acrylate, etc., and these may be used alone or in combination of two or more. be able to.

Other monomers (D) include 2-methylpropanesulfonic acid (meth) acrylamide, styrenesulfonic acid and their monovalent metal salts such as sodium, divalent metal salts such as calcium, and ammonium. Salts, organic amine salts, and the like.
More than one species can be used in combination.

As the water-soluble polymer having a carboxyl group in the molecule of the present invention, a copolymer obtained by copolymerizing the above monomers (A) and (B), or (A)
To (C) and, if necessary, a copolymer obtained by copolymerizing the monomer (D).
In the case of the copolymer (1), the amount of the monomer (A) is preferably from 3 to 98 mol%, more preferably from 5 to 95 mol%, and the amount of the (B) monomer is preferably 2-9
It is 7 mol%, more preferably 5 to 95 mol%.

In the case of the above copolymer, the amount of the monomer (A) is preferably 3 to 25 mol%.
And more preferably 4 to 20 mol%, and still more preferably 5 to 17 mol%, and the amount of the monomer (B) used is preferably 55 to 75 mol%. The amount used is preferably from 5 to 35 mol%, and the amount of the monomer (D) used is preferably from 0 to 10 mol%, more preferably from 0 to 8 mol%.

The method for producing the copolymer is as follows.
There is no particular limitation, and for example, a known polymerization method such as solution polymerization or bulk polymerization using a polymerization initiator can be employed. In this case, the solvent used for the polymerization includes water, methyl alcohol,
Examples thereof include lower alcohols such as ethyl alcohol and isopropyl alcohol, aromatic or aliphatic hydrocarbons such as benzene, toluene, xylene and cyclohexane, and ketone compounds such as acetone and methyl ethyl ketone. Of these, water is used as a solvent. Is preferred.

As the polymerization initiator in the case of performing aqueous solution polymerization, a metal salt or ammonium salt of persulfuric acid, hydrogen peroxide,
A water-soluble polymerization initiator such as azobis-2-methylpropionamidine hydrochloride is used. Further, an accelerator such as sodium hydrogen sulfite and a chain transfer agent such as mercaptoethanol, mercaptoacetic acid and mercaptopropionic acid can be used in combination.

The weight average molecular weight (Mw) of the copolymer is preferably 5,000 to 200,000, more preferably 10,000 to 100,000, and further preferably 20,000 to 80,000. If the weight average molecular weight is too small, a sufficient dispersing effect may not be obtained. On the other hand, if the weight average molecular weight is too large, an agglomeration action may be exhibited and the dispersing effect may be reduced.

In the case of the above-mentioned acidic group-containing polymer, all of the acid may be converted into an amine salt, but it is preferable to partially neutralize the acid with an amine.

The defoaming agent for a cement composition of the present invention can be suitably used for hydraulic cements such as Portland cement, alumina cement and various mixed cements.

The method of using the defoaming agent for a cement composition of the present invention is not particularly limited, but is a method of mixing and dissolving in water and adding it simultaneously to the cement composition, or adding it to the already kneaded cement composition. Any method such as a method can be adopted. The antifoaming agent of the present invention is an AE agent, AE
Water reducing agent, high performance water reducing agent, high performance AE water reducing agent, superplasticizer,
Can be used in combination with aqueous solutions of cement admixtures such as setting retarders, fast-acting agents, other defoamers, thickeners, waterproofing agents, swelling agents, shrinkage reducing agents, silica sand, blast furnace slag, fly ash, silica fume, calcium carbonate, etc. . In addition, as a water-soluble admixture,
It can be used by premixing it with an aqueous solution of a cement dispersant such as a water reducing agent, a fluidizing agent, or an AE agent, but can be used without losing the defoaming effect even when powdered with the mixed cement dispersant aqueous solution. is there.

The amount of the antifoaming agent for the cement composition of the present invention added to the cement can be appropriately adjusted according to the air entrainment of the cement composition, but usually, the salt of the above organic amine (antifoaming agent) Of the cement, preferably 0.0001 to 5% by weight, more preferably 0.0005% by weight, based on the cement.
To 3% by weight, more preferably 0.001 to 3% by weight. If the added amount of the defoaming agent is too small, a sufficient defoaming effect may not be obtained, while if it is too large, the amount of air in the concrete will be reduced too much, causing a decrease in durability such as freeze-thaw resistance. And may be economically disadvantageous.

The defoaming agent for the cement composition of the present invention may be used as a high-performance AE water reducing agent, a high-performance water reducing agent, a superplasticizer,
It is suitable as an antifoaming agent such as a slump recovery agent.

[0044]

The defoaming agent for a cement composition of the present invention has an excellent defoaming effect, can adjust the amount of air bubbles in concrete and mortar to an appropriate amount, and is difficult with conventional defoaming agents. Uniform mixing of the defoaming agent and the aqueous solution of the admixture becomes possible, and an aqueous solution of the cement admixture without separation of the defoaming agent can be obtained even when stored for a long time, and the addition of the antifoaming agent becomes extremely simple. .

[0045]

EXAMPLES The present invention will be described more specifically below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

Example 1, Comparative Example 1 Four kinds of acids, sulfuric acid, hydrochloric acid, acetic acid, and gluconic acid, were neutralized with dimethyllaurylamine, and defoamers A-1 to A-4 (organic). Amine salt) was prepared (Example 1). A mortar test was performed using these organic amine salts in combination with a commercially available high-performance AE water reducing agent. In addition, B-1 is a thing without an antifoaming agent added (Comparative Example 1). Table 1 shows the results.

Materials used, mortar preparation, mortar production and test methods are shown below. <Materials> Cement: Ordinary Portland cement (Sumitomo Osaka Cement Co.) Fine aggregate: Mountain sand from Ichihara Mixing water: Tap water High-performance AE water reducing agent: Polycarboxylic acid ether type (NMB Co., Ltd.) <Mortar mix> Water / cement ratio (W / C) = 44.7% by weight Fine aggregate / cement ratio (S / C) = 1.93 (weight ratio) The amount of cement per batch is 0.8 kg <Mortar production and test method > A cement and fine aggregate were stirred for 30 seconds using a kneader-mixer described in JIS R5201, and kneading water, an antifoaming agent and a high-performance AE water reducing agent were mixed and added, and kneaded for 90 seconds to produce a mortar. . The high-performance AE water reducing agent was added to cement in a solid content of 0.12% by weight. For the obtained mortar, a mini slump (JIS A 1173) and an air volume (JIS A 1
174) was measured.

[0048]

[Table 1] * 1: Addition amount of organic amine to cement (% by weight)

Example 2, Comparative Example 2 Cement dispersant methacrylic acid / methoxypolyethylene glycol methacrylate (number of moles of ethylene oxide added: 23 m)
ol) Aqueous solution of copolymer (copolymerization ratio (mol%)
= 70/30, weight average molecular weight (Mw) = 36,000
0), various organic amines were added in the amounts shown in Table 2, and the pH was adjusted to 7 with an aqueous sodium hydroxide solution.
An antifoaming agent excellent in the effect as a cement dispersant of A-5 to A-8 in which a part of the carboxyl group of methacrylic acid as a polymer constituent is a salt of an organic amine was produced (Example 2). ). In addition, it prepared so that the solid content of the said defoaming agent might be set to 30 weight%. Further, as Comparative Example 2, the case where no antifoaming agent was added (B-2) and the commercially available antifoaming agent (B-3) were used.

Next, a copolymer (cement dispersant)
Table 2 shows the amount of the organic amine added to. Further, a 30% by weight aqueous solution of the defoaming agent was subjected to a standing stability test (visual appearance judgment). The results are also shown in Table 2.

[0051]

[Table 2] * 1: Amount added to polymer (% by weight) * 2: Nicofix 800 (Ethoxypropoxylate of long-chain alcohol manufactured by Onoda Co., Ltd.)

A mortar test was performed using the defoaming agents shown in Table 2. Table 3 shows the results.

The materials used, mortar preparation, mortar production and test methods are shown below. <Material> Cement: Ordinary Portland cement (Sumitomo Osaka Cement Co.) Fine aggregate: Mountain sand from Kasumigaura Kneading water: Tap water <Mortar mix> Water / cement ratio (W / C): 38.8% by weight Fine aggregate / Cement ratio (S / C): 1.93 (weight ratio) Defoamer addition amount: 0.11% by weight added to cement (B-2 is addition amount of cement dispersant) Target minislamp: 9. 0 ± 0.5cm Target air volume: 4.0 ± 0.5% <Mortar production and test method>
The mixture was taken in a kneading machine for mechanical kneading described in 5201, and after adding a defoaming agent and kneading water, the mixture was stirred for 90 seconds to produce a mortar. For the obtained mortar composition, a mini slump (JIS A 1173) and an air volume (JIS A 1
174) was measured.

[0054]

[Table 3] From the results in Tables 2 and 3, it can be seen that the defoamer of Comparative Example 2 was not added (B-
In the case of (2), no separation occurs with time, but the amount of air is too large. In addition, the conventional commercial product (B-3) has a small amount of air relative to the target amount of air and does not completely dissolve, but separates over time. On the other hand, Example 2 (A-5 to A
In the case of -8), there is no separation over time, and it is recognized that both the minislump and the air amount satisfy the target values.

Example 3, Comparative Example 3 Monomer compositions shown in Table 4 were produced by known radical polymerization, and dimethyl laurylamine was added to the resulting polymer aqueous solution (cement dispersant) and mixed. Antifoaming agents of 9 to A-12 were prepared (solid content: 30% by weight).

[0056]

[Table 4] * 1: Amount of dimethyl laurylamine added to polymer (% by weight) A: methacrylic acid B: methyl methacrylate C: 2-hydroxyethyl methacrylic acid D: 2-acrylamide 2-methylpropanesulfonic acid E: methoxypolyethylene glycol methacrylate ( F: Methoxy polyethylene glycol methacrylate (Ethylene oxide addition mole: 23 mol)

Next, using the defoamer (Example 3) having the cement dispersing effect of A-9 to A-12 shown in Table 4,
A concrete test was performed. Table 6 shows the amount of the defoamer added and the results. In addition, B-4 is a monomer composition of A-9 without dimethyllaurylamine added (Comparative Example 3; only cement dispersant).

The materials used, concrete preparation, concrete production, and test methods are described below. <Materials> Cement: Ordinary Portland cement (Sumitomo Osaka Cement Co.) Fine aggregate: Ichihara mountain sand Coarse aggregate: Ichihara mountain sand Mixing water: Tap water <Concrete mix> Table 5 shows concrete mix, slump, air The target value of quantity was shown.

[0059]

[Table 5] <Concrete production and test method>
The mixture was charged into a 150-L pan-type forced kneading mixer with the content shown in Table 2 and kneaded for 3 minutes to produce concrete. Slump (JIS A 1
101), and the amount of air (JIS A 1116) was measured.

[0060]

[Table 6] * 1: Addition amount of solid content of defoaming agent or cement dispersant to cement (% by weight) Based on the results in Table 6, the antifoaming agent of the present invention of Example 3 has both excellent defoaming effect and cement dispersing effect. Is recognized.

Claims (2)

[Claims] 1. An antifoaming agent for a cement composition comprising an unsubstituted or hydroxyl- or halogen-substituted alkyl or alkenyl group-containing organic amine salt having 6 to 24 carbon atoms which may have an amide bond. 2. The antifoaming agent according to claim 1, wherein the salt of the organic amine is a salt of the organic amine and an acidic group-containing polymer.