KR100615640B1 - An Improved Production Method of High Performance Concrete Dispersant - Google Patents

Abstract

The present invention provides an optimal reaction for the amount of the inorganic acid catalyst which is a direct ester reaction catalyst in the method for producing polyalkylene glycol (meth) acrylate by direct ester reaction of polyalkylene glycol monoalkyl ether and (meth) acrylic acid. The reaction rate can be economically performed by shortening the ester reaction time as desired to obtain the rate, and at this time, the inorganic acid catalyst used is neutralized with an alkali compound after the completion of the ester reaction to form a salt, and then the ester reaction product. Characterized in that the removal from. As described above, the polyalkylene glycol (meth) acrylate monomer mixture from which the salt is removed is copolymerized with other monomers to prepare a concrete dispersant. The salt of the inorganic acid catalyst for ester reaction in the final product is polyalkylene glycol (meth) acrylic. When it is 0 to 1% by weight of the weight weight, it is characterized in that the concrete dispersant having excellent dispersibility and excellent slump retention ability is produced.

Concrete dispersant, slump, unsaturated carboxylic acid, ester reaction, polyalkylene glycol monoalkyl ether, (meth) acrylic acid, copolymerization

Description

Improved Production Method of High Performance Concrete Dispersant

The present invention relates to a high performance concrete dispersant and a method of manufacturing the same. More specifically, the concrete dispersing agent and its method of improving the dispersibility of the cement present in the concrete to have high fluidity even with a small amount of water, improve the ability to maintain the dispersion of cement particles, maintain the fluidity of the concrete for a long time and improve workability It is about.

Recently, due to problems such as the demand for improving the strength of concrete structures and the delay of transporting concrete to the workplace due to traffic congestion, interest in the fluidity and dispersion of concrete in structures is increasing.

In order to improve the strength of concrete, it is important to reduce the amount of water input compared to the amount of cement used. However, reducing the amount of water used does not provide the mobility of concrete. Therefore, a high performance concrete dispersant is essential. In addition, there is a problem that the efficiency of the pouring work is drastically deteriorated due to the increase in the pump pressure or blockage of the concrete composition due to the change of the quality of the concrete mixture and the slump loss due to the delay of the transport time of the concrete to the pouring site, the waiting time at the site, etc. The slump retention capacity of the concrete dispersant is very necessary.

Dispersants for concrete admixtures are classified into lignin-based, polyol-based, oxy-organic acid-based, polycarboxylic acid-based, melanin-based, naphthalene-based, etc. according to their chemical composition. 20-30% is called a high-performance dispersing agent, and a poly carboxylic acid system is one having two or more carboxylic acid groups (-COOH) in its molecule. In order to prepare such a polycarboxylic acid-based concrete dispersant, a conventional ester reaction or transesterification reaction of (meth) acrylic acid or methyl methacrylate, which is an unsaturated carboxylic acid capable of polymerization with a hydrophilic group polyalkylene glycol monoalkyl ether, is carried out. After preparing a polyalkylene glycol (meth) acrylate, a polycarboxylic acid-based dispersant is prepared through radical copolymerization with a carbonic acid monomer.

In the prior art shown in Korean Patent No. 10-0247527, polyalkylene glycol methacrylate is prepared by a transesterification reaction of methyl methacrylate and polyalkylene glycol monoalkyl ether. In this step, excess methyl methacrylate is refluxed to the reactor to remove the reaction byproduct methanol by azeotropy, and an alkali base such as sodium hydroxide is used as a catalyst. This method requires a step of separating methanol from the azeotropic boiling methylmethacrylate instead of short reaction time and completely removes unreacted methylmethacrylate present in the reaction product. There are problems such as the need to remove the used base through filtering and the like. A method for producing polyalkylene glycol methacrylate by the direct ester method is disclosed in Japanese Patent 11-71152.

The production method known to the known fact that the (meth) acrylic acid is directly esterified with polyalkylene glycol monoalkyl ether to produce polyalkylene glycol (meth) acrylate. Using less catalyst and excessive use of solvents such as benzene to azeotropically remove the water produced as by-products during the reaction maximizes the production of polyalkylene glycol (meth) acrylates, which are unwanted impurities produced during the reaction. After suppressing the reaction, the content of polyalkylene glycol (meth) acrylate becomes 0-5% or less by weight ratio of polyalkylene glycol (meth) acrylate.

However, the use of an acid catalyst is limited to 0.5% by weight of the total weight of the total weight of polyethylene glycol monomethyl ether and (meth) acrylic acid used as raw materials, so that the reaction time is extremely slow to about 25 hours, and (meth) acrylic acid during the reaction. There is a high risk of polymerization reaction, and due to the long reaction time, it is difficult to be an economical production method. On the other hand, it is also a burden on the process to remove solvents such as benzene that are used in excess after the completion of the reaction. The production of polyalkylene glycol (meth) acrylates, which are unwanted by-products claimed in the prior art, also does not show specific methods that can be suppressed or controlled in the specification of the prior art.

Therefore, there is a problem that can not set the control variable to suppress the production of by-products during the manufacturing process to determine the quality of the product after the reaction by analyzing the content of polyalkylene glycol (meth) acrylate after the reaction.

As described above, the polyalkylene glycol (meth) acrylate prepared by the direct ester method or the transesterification reaction is copolymerized with an unsaturated carboxylic acid such as acrylic acid or methacrylic acid, and then neutralized to prepare a concrete dispersant as a final product. .

The technical problem to be achieved in the present invention, by increasing the reaction rate in the production of polyethylene glycol (meth) acrylate by direct ester reaction to provide a manufacturing method that can control the quality of the product while at the same time economical production An object of the present invention is to provide a method for producing a high-performance polycarboxylic acid dispersant using the above product.

In addition, the dispersant of the present invention is to provide a method for producing a dispersant having a good dispersing ability, very excellent slump retention ability.

In order to achieve the above object, the inventors of the present invention have steadily studied, and thus, in the direct ester reaction of polyalkylene glycol monoalkyl ether represented by the following [Formula 1] and unsaturated carboxylic acid represented by [Formula 2] In preparing the polyalkylene glycol (meth) acrylate represented by [Formula 3], if the amount of a general inorganic acid catalyst such as sulfuric acid used as a catalyst is too small, the reaction rate is extremely slow and economical efficiency of the manufacturing process It was found that the degradation and the amount of acid catalyst sufficiently used to obtain a constant reaction rate have a significant adverse effect on the dispersibility and retention ability of the final product.

[Formula 1]

(Wherein R ₁ is an alkyl group having 1 to 22 carbon atoms, R ₂ is one or a mixture of two or more kinds of alkylene groups having 2 to 4 carbon atoms, and n is 1 to 100).

[Formula 2]

(Wherein R ₃ is a hydrogen atom or a methyl group)

[Formula 3]

(Wherein R ₁ , R ₂ , R ₃ , n are as defined above)

As a result of researches to solve the above problems, when the inorganic acid catalyst used and the inorganic salt generated when neutralizing the inorganic acid catalyst with a base such as sodium hydroxide remain in the final product, the dispersion capacity and retention capacity of the final product concrete dispersant It was found to have great adverse effects.

Accordingly, the present invention uses polyalkylene glycol (meth) by direct ester reaction using unsaturated carboxylic acid [Formula 1] and polyalkylene glycol monoalkyl ether [Formula 2] as raw materials and a general inorganic acid catalyst such as sulfuric acid. In the reaction step of synthesizing the acrylate, the residual acid catalyst is removed after completion of the reaction, and the polyalkylene glycol (meth) acrylate and the unsaturated carboxylic acid in which the inorganic acid catalyst is removed are copolymerized to prepare a high-performance concrete dispersant. It consists of doing.

Referring to the process of preparing the dispersant of the present invention,

Preparing a polyalkylene glycol (meth) acrylic acid ester monomer solution by reacting a polyalkylene glycol monoalkyl ether and an unsaturated carboxylic acid under an organic acid catalyst in an organic solvent; Distilling off the organic solvent from the solution; Adding water to the residual solution such that the polyalkylene glycol (meth) acrylic acid ester monomer is in a range of 70 to 95% by weight; Adding a base to the aqueous solution to neutralize the reactive inorganic acid; Filtering the salt generated from the inorganic acid catalyst and the base; And preparing a copolymer including the separated polyalkylene glycol (meth) acrylic acid ester monomer solution. It characterized in that to produce a high-performance dispersant including.

The following describes the present invention in more detail.

In the present invention, in the direct ester reaction for synthesizing polyalkylene glycol (meth) acrylate, the molar ratio of unsaturated carboxylic acid and polyalkylene glycol monoalkyl ether as a reaction raw material is 1: 1 to 5: 1, more preferably. 1: 1 to 3: 1 are suitable.

In order to remove the generated water generated during the reaction, a solvent which forms an azeotrope with the generated water may be used. Examples include aliphatic hydrocarbons such as benzene and toluene, alicyclic compounds such as cyclohexane, and aliphatic hydrocarbons such as n-hexane. .

As the catalyst that can be used for the ester reaction, inorganic acids such as sulfuric acid, paratoluene sulfonic acid, methane sulfonic acid, nitric acid and phosphoric acid are suitable, and an amount of 1 to 10% by weight of the amount of polyalkylene glycol monoalkyl ether administered to the reaction is suitable. More preferably 2 to 8% by weight. If the amount of the catalyst is too small, the reaction rate is considerably lowered to cause problems in economical efficiency. If the amount is too large, the reaction rate is increased, but many side reactions such as polymerization of unsaturated carboxylic acid occur.

In order to prevent superposition | polymerization of unsaturated carboxylic acid during reaction, a polymerization inhibitor is used, Hydroquinones and phenocyazines which are well-known polymerization inhibitors can be used. The reaction temperature is suitable at 75 ~ 120 ℃ at normal pressure.

After the completion of the ester reaction, solvents such as benzene, which have been added, are removed under reduced pressure, an aqueous solution is prepared by mixing water with the reaction product so that the weight of the reaction product is 70 to 95% by weight, and then neutralizing the salt of the acid catalyst present in the reaction product. Form and remove. The above range is for removing the salt formed by neutralizing the acid catalyst of the reactor, in the case below the above range, the salt is not precipitated because there is too much water, and if it is higher than the above range, the precipitate salt is effectively separated because the water is too small. In this invention, it is very important to control the solid content of the aqueous solution in the above range. In addition, by adjusting to the above range, the component of the acid or salt in the final polymer of the present invention can be achieved in the range of the present invention.

There are many ways to remove it.

In one method, the same amount of sodium hydroxide solution used as the acid catalyst is used, and when sulfuric acid is the catalyst, sodium sulfate is formed, and when left at room temperature for a while, sodium sulfate, which has a relatively high specific gravity, is easily separated to remove salts.

Another method is to add a solid salt such as MgO and CaO to the aqueous solution of the reaction product to neutralize and precipitate the acid catalyst, and to remove the salt of the acid catalyst efficiently by removing through filtering and the like.

Said neutralization is made at 0-50 degreeC, preferably 30-40 degreeC, and the efficiency which removes a reactive inorganic acid is more efficient.

As described above, the reaction product from which the acid catalyst is removed is copolymerized with polyalkylene glycol (meth) acrylate [Formula 3] and (meth) acrylic acid monomer [Formula 2] to synthesize a final product of the concrete dispersant. Since the polyalkylene glycol (meth) acrylate and the (meth) acrylic acid monomer are present at the same time in the reaction product prepared as described above, the reaction product may be copolymerized as it is or by adding another copolymerizable monomer to perform the copolymerization reaction. You can. Other copolymerizable monomers include maleic acid, fumaric acid, allyl alcohols, (poly) ethylene glycol allyl ether, and the molecular weight after copolymerization is 15,000 to 50,000 when the molecular weight is analyzed by gel permeation chromatography (GPC). This is suitable.

As long as the polymerization initiator is water-soluble, general persulfates such as ammonium persulfate, sodium persulfate and potassium sulfate are suitable.

A chain transfer agent can be used as needed for molecular weight adjustment, and as a chain transfer agent, well-known compounds, such as a merceto propionic acid, a merceto acetic acid, a merceto propionic acid 2-ethyl hexyl ester, can be used.

50-150 degreeC is suitable for copolymerization reaction temperature, but 50-120 degreeC is preferable. After the completion of the copolymerization reaction, the product is neutralized with basic materials such as alkali metal hydroxide, alkaline earth metal hydroxide or amine such that the pH of the product is 6.5 to 7.5. The concrete dispersant having the copolymer obtained as described above as a main component improves the dispersibility of the cement and the ability to delay the hydration reaction when it is added to a cement composition composed of cement and water. At this time, the salt of the inorganic acid catalyst is removed before the copolymerization reaction in the copolymer final product obtained as described above, and the dispersion capacity of the concrete dispersant prepared when the weight of the polyethylene glycol (meth) acrylate is 0 to 1% by weight. Maintenance capacity is greatly improved.

In the following Examples the present invention will be described in more detail. However, the present invention is not limited by the following examples.

Example 1

712.5 g of polyethylene glycol monomethyl ether having an average molecular weight of 475 was added to a 2-liter glass reactor equipped with a thermometer, a stirrer, a reaction water separator, and a reflux condenser, and 15 g of sulfuric acid, a reaction catalyst, was added thereto. 1.7 g of quinone was added to completely dissolve the hydroquinone. Thereafter, 194 g of methacrylic acid was quantified and added to the reactor, 400 g of benzene was injected, and the temperature was raised to reflux to directly start the ester reaction. After confirming that a predetermined amount of generated water occurred, benzene was removed from the reactor under reduced pressure, and water was added to the reaction product to prepare an 85% aqueous solution.

24.5 g of 50 wt% caustic soda (NaOH) was added to the reaction product to which water was added, stirred at room temperature, and the sulfuric acid used as a catalyst was completely neutralized. After neutralization is completed, the stirring is stopped for a while, and the whole solution is injected into the separatory funnel. If the solution is held for a while, the sodium sulfate salt generated by neutralization is separated from the solution and phase separated at the bottom of the solution to form a layer of sodium sulfate salt. After the phase separation is complete, the bottom sodium sulfate salt layer is removed from the separating funnel.

As described above, 26.5 g of acrylic acid and 26.4 g of methacrylic acid were added to 320 g of the ester reaction product from which the salt of the inorganic acid catalyst was completely removed, and 2.8 g of mercetopropionic acid was mixed with a chain transfer agent to prepare a copolymerization mixture.

155 g of water was first introduced into a 2 liter glass reactor equipped with a stirrer, replaced with nitrogen, and the reaction temperature was maintained at 80 ° C. The copolymerization mixture was added dropwise to the reactor over 4 hours, 2.4 g of a polymerization initiator and 2.4 g of ammonium sulfate were dissolved in 180 g of water, and added dropwise together with the copolymerization mixture for 5 hours. After the dropwise addition was completed, the reaction was completed for 1 hour to complete the copolymerization reaction, and then the copolymerization reaction was terminated. After the reaction was completed, the pH of the product was neutralized to ca. 6.5-7.5 with 33 wt% caustic soda. After completion of the copolymerization reaction, the salt of the residual inorganic acid catalyst was 0.2% by weight based on the prepared dispersant. Moreover, the weight average molecular weight of the obtained copolymer was 24,000.

Example 2

When neutralizing sulfuric acid which is an inorganic acid catalyst of ester reaction, it is the same as [Example 1] except that MgO powder which is a solid base is used instead of 50% caustic soda. 7.2 g of MgO powder was added to an aqueous 85% ester reaction product, followed by stirring. After confirming that the reaction product was neutralized, the salts of MgO and sulfuric acid used were removed by filtration, followed by copolymerization.

The weight average molecular weight of the concrete dispersant prepared after the copolymerization reaction was 28,000, and the salt of sulfuric acid as an inorganic acid catalyst was 0.15 wt% of the weight of polyethylene glycol methacrylate.

Example 3

Into the same reactor used in Example 1, 827 g of polyethylene glycol monoethyl ether having a molecular weight of 1068 was added and maintained at 80 ° C., followed by 20 g of sulfuric acid as a reaction catalyst. 1.7 g of hydroquinone was added and dissolved as a polymerization inhibitor, and then 204 g of methacrylic acid was added, 400 g of benzene, which was a product water extraction solvent, was injected, and the temperature was raised to start the reaction. After a predetermined amount of water generated, benzene was removed under reduced pressure, and water was mixed to prepare an 80% aqueous solution.

At room temperature, 32.7 g of 50% caustic soda was added to the aqueous solution, followed by stirring to terminate the neutralization reaction, and the mixture was transferred to a separatory funnel for stagnation. Inorganic acid catalyst salts were separated from the mixture on the bottom of the separating funnel and then completely removed.

16 g of acrylic acid and 16 g of methacrylic acid were mixed with 320 g of the aqueous solution from which the salt was removed, and 2.8 g of merceto propionic acid was mixed with a chain transfer agent to prepare a copolymerization mixture. 155 g of water was first added to a 2 liter glass reactor equipped with a stirrer, and the reaction temperature was maintained at 80 ° C. after replacing the inside of the reactor with nitrogen. The copolymer mixture was added dropwise to the reactor over 4 hours, and 2.4 g of ammonium persulfate, a polymerization initiator, was dissolved in 180 g of water and added dropwise together with the copolymer mixture for 5 hours. After the dropwise addition of the initiator was completed, 80 ℃ was maintained for 1 hour to complete the polymerization reaction.

After completion of the copolymerization reaction, the product was neutralized with ca.

The weight average molecular weight of the concrete dispersant thus prepared was 32,000, and the salt of the residual inorganic acid catalyst was 0.32 wt% of the weight of polyethylene glycol methacrylate.

Comparative Example 1

It is the same as Example 1 except that sulfuric acid, which is an ester reaction catalyst, is not removed after neutralization before the copolymerization reaction. After completion of the copolymerization reaction, the weight average molecular weight of the final concrete dispersant was 26,000, and the inorganic acid catalyst salt in the final product was 1.85 wt% of the weight of polyethylene glycol methacrylate.

Comparative Example 2

It is the same as [Example 3] except that sulfuric acid which is an ester reaction catalyst is not removed after neutralization before the copolymerization reaction. After completion of the copolymerization reaction, the weight average molecular weight of the final concrete dispersant was 33,000, and the inorganic acid catalyst salt in the final product was 2.3 wt% of the weight of polyethylene glycol methacrylate.

Experimental Example

Concrete test

Cement was used as normal Portland cement, and aggregates were also used as general water sand and hard sandstone crushed stone. As the cement dispersant, dispersants prepared in Examples 1 to 3 and Comparative Examples 1 and 2 were used, respectively. Concrete mixing conditions are 188 kg water, 833 kg sand and 997 kg gravel per 300 kg cement. Concrete was blended under the above conditions, and the slump over time was measured as defined in KS F2560, and the performance of the concrete dispersant was shown in [Table 1].

TABLE 1

As shown in Table 1, the performance of the concrete dispersant removed after the neutralization of the inorganic acid catalyst before the copolymerization reaction was superior to that of the dispersant not doing so. The reason is that the acid catalyst for the residual ester reaction may adversely affect the copolymerization reaction, and it is assumed that the salt of the inorganic acid catalyst remaining in the final product adversely affects the dispersibility and the holding ability.

That is, as in Comparative Example 1, the dispersant which does not belong to the scope of the present invention was inferior to the effect of the present invention even when used in excess, it was found that the flowability is very sharply dropped when using the same amount as the present invention. .

Polyalkylene glycol (meth) acrylate using a desired amount of inorganic acid catalyst in a method of preparing a monomer component containing polyalkylene glycol (meth) acrylate by direct ester reaction, and then polymerizing and preparing a concrete dispersant Provides a method of producing a concrete dispersant with excellent dispersibility and slump retention of the concrete dispersant prepared by neutralizing and removing the inorganic acid catalyst after the ester reaction and removing the copolymer after the ester reaction. can do.

Claims (4)

Preparing a polyalkylene glycol (meth) acrylic acid ester monomer solution by reacting a polyalkylene glycol monoalkyl ether and an unsaturated carboxylic acid under an organic acid catalyst in an organic solvent; Distilling off the organic solvent from the solution; Adding water to the residual solution such that the polyalkylene glycol (meth) acrylic acid ester monomer is in a range of 70 to 95% by weight; Adding a base to the aqueous solution to neutralize the reactive inorganic acid; Filtering the salt generated from the inorganic acid catalyst and the base; And Preparing a copolymer comprising a separated polyalkylene glycol (meth) acrylic acid ester monomer solution; Method for producing a concrete dispersant comprising a. The method of claim 1, The salt of the inorganic acid catalyst is a method for producing a concrete dispersant, characterized in that containing less than 1% by weight relative to the dispersant. The method of claim 2, The copolymer is a method for producing a concrete dispersant, characterized in that it contains any one or more selected from (meth) acrylic acid, (meth) acrylate, maleic acid, fumaric acid, allyl alcohol, polyethylene glycol allyl ether. A cement composition having stable flowability prepared by mixing a dispersant prepared by the method of claim 1 with a salt of an inorganic acid catalyst in an amount of 1% by weight or less with a cement mixture.