KR102561216B1 - Cement additive and cement composition comprising the same - Google Patents

Abstract

The present invention relates to a method for preparing a cement additive having a wide molecular weight distribution and exhibiting excellent water reducing properties and slump retention properties when applied to a cement composition, and a cement composition having improved workability and excellent strength properties, including a cement additive prepared according to the method.

Description

Method for manufacturing cement additive and cement composition comprising the cement additive prepared thereby

The present invention relates to a method for preparing a cement additive and a cement composition comprising the cement additive prepared thereby.

Cement compositions such as cement paste, mortar, and concrete are hydraulic reactants that harden by reaction with water, and are widely used as building materials.

These cement compositions have different physical properties such as compressive strength after curing according to the amount of water used. Depending on the elapsed time after the addition of water, the fluidity of the composition is remarkably lowered, resulting in a decrease in workability. In this case, the total amount of water used in the cement composition is limited because adding additional amounts of water to improve workability lowers the compressive strength and causes cracks. Accordingly, various cement additives have been developed to maintain the dispersibility of the cement composition while reducing the amount of water used.

Various cement dispersants are used to improve the water reducing properties of cement compositions, but in general, when highly water reducing hydraulic compositions are prepared using cement dispersants, there is a problem that slump loss is significant and workability and workability are reduced.

Accordingly, in order to prevent slump loss, attempts have been made to use a water-soluble polycarboxylic acid-based copolymer having slump loss prevention performance as a cement dispersant. Examples of the water-soluble polycarboxylic acid-based copolymer include a water-soluble vinyl copolymer obtained by copolymerizing methacrylate, a copolymer of maleic anhydride and alkenyl ether, or derivatives thereof. However, the conventional method using the above water-soluble copolymer as a cement dispersant has a drawback that prevention of slump loss is insufficient.

Japanese Unexamined Patent Publication No. 8-12396 discloses a polycarboxylic acid-based concrete additive, and discloses that an oxyalkylene group added to a polyalkylene glycol monoester-based monomer has an advantage of excellent curing characteristics within a specific range. However, the technology in the above document does not have a satisfactory level of slump retention, and early strength properties are not yet sufficient, so further improvement in performance is required.

On the other hand, in the case of polycarboxylic acid-based cement additives, various performances are expressed depending on the composition and molecular weight distribution of monomers. In the case of conventionally used polycarboxylic acid-based cement additives, there is a problem in that the application area is limited because they are manufactured to have a molecular weight distribution value in a limited narrow region.

Japanese Unexamined Patent Publication No. 8-12396

In order to solve the problems of the prior art as described above, the present invention is to provide a method for preparing a cement additive having a wide molecular weight distribution to realize excellent water reducing properties when applied to a cement composition and at the same time exhibiting excellent strength properties.

In addition, the present invention is to provide a cement composition having improved workability and excellent strength properties, including the cement additive prepared according to the above manufacturing method.

In the present specification, adding a monomer mixture including a (alkoxy) polyalkylene glycol mono (meth) acrylic acid ester monomer and a (meth) acrylic acid monomer to a reactor and a first polymerization initiator; preparing a copolymer by adding a second polymerization initiator while raising the temperature inside the reactor to 85 to 95 °C; and neutralizing by adding an ethanolamine-based or alkyldiethanolamine-based neutralizing agent solution to a reactor containing the prepared copolymer.

After the addition of the second polymerization initiator, the step of reducing the temperature of the reactor to 75 to 80 ℃ may be included.

The first polymerization initiator and the second polymerization initiator may each independently be one or more selected from the group consisting of ammonium persulfate, magnesium persulfate, sodium persulfate, and hydrogen persulfate.

The first polymerization initiator may be included in an amount of 0.5 to 1.0 parts by weight based on 100 parts by weight of the monomer mixture.

The second polymerization initiator may be included in an amount of 0.05 to 0.5 parts by weight based on 100 parts by weight of the monomer mixture.

Before adding the monomer mixture and the first polymerization initiator, a third polymerization initiator may be further included in the reactor.

The third polymerization initiator may be at least one selected from the group consisting of ammonium persulfate, magnesium persulfate, sodium persulfate, and hydrogen persulfate.

The third polymerization initiator may be included in an amount of 0.1 to 0.5 parts by weight based on 100 parts by weight of the monomer mixture.

The (alkoxy) polyalkylene glycol mono (meth) acrylate monomers include methoxy polyethylene glycol mono (meth) acrylate, methoxy polypropylene glycol mono (meth) acrylate, methoxy polybutylene glycol mono (meth) acrylate, methoxy polyethylene glycol polypropylene glycol mono (meth) acrylate, methoxy polyethylene glycol polybutylene glycol mono (meth) acrylate, methoxy polypropylene glycol polybutylene glycol Col mono(meth)acrylate, methoxypolyethylene glycol polypropylene glycol polybutylene glycol mono(meth)acrylate, ethoxypolyethylene glycol mono(meth)acrylate, ethoxypolypropylene glycol mono(meth)acrylate, ethoxypolybutylene glycol mono(meth)acrylate, ethoxypolyethylene glycol polypropylene glycol mono(meth)acrylate, ethoxypolyethylene glycol polybutylene glycol mono It may be at least one selected from the group consisting of (meth)acrylate, ethoxypolypropylene glycol polybutylene glycol mono(meth)acrylate, and ethoxypolyethylene glycol polypropylene glycol polybutylene glycol mono(meth)acrylate.

The (meth)acrylic acid-based monomer may be at least one selected from the group consisting of acrylic acid, methacrylic acid, and monovalent metal salts, divalent metal salts, ammonium salts, and organic amine salts of these acids.

The monomer mixture may further include one or more (meth)acrylic acid ester-based monomers selected from the group consisting of 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, and monovalent metal salts, divalent metal salts, ammonium salts, and organic amine salts thereof.

The neutralizing agent solution may be at least one selected from the group consisting of ethanolamine, diethanolamine, triethanolamine, methyldiethanolamine, ethyldiethanolamine and butyldiethanolamine.

In the copolymerization step, a thiol-based chain transfer agent may be further included.

The cement additive may have a weight average molecular weight of 33,000 to 38,000.

The cement additive may have a polydispersity index (PDI) of 2.3 to 2.7.

In addition, in the present specification, a cement composition comprising 0.001 to 5 parts by weight of the cement additive prepared according to claim 1 based on 100 parts by weight of cement is provided.

According to the manufacturing method of the cement additive of the present invention, a polycarboxylic acid-based cement additive having a wide molecular weight distribution can be prepared, and when added to a cement composition, excellent water reducing properties and at the same time, excellent slump retention properties can be realized.

In addition, according to the cement composition of the present invention, due to the cement additive having a wide molecular weight distribution prepared according to the above manufacturing method, the composition has excellent fluidity over time, has good workability, and has low slump loss after curing and excellent strength characteristics.

The present invention comprises the steps of adding a monomer mixture and a first polymerization initiator to a reactor; preparing a copolymer by adding a second polymerization initiator while raising the temperature inside the reactor to 85 to 95 °C; and adding a neutralizer solution to a reactor containing the prepared copolymer to neutralize it.

Hereinafter, a method for preparing a cement additive and a cement composition according to specific embodiments of the present invention will be described in more detail.

Terms used in this specification are only used to describe exemplary embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as "comprise", "comprise" or "having" are intended to indicate that an embodied feature, number, step, component, or combination thereof exists, but it should be understood that the presence or addition of one or more other features, numbers, steps, components, or combinations thereof is not precluded.

Also, terms such as first and second used in this specification are used to describe various components, and the terms are used only for the purpose of distinguishing one component from another component.

Since the present invention can have various changes and various forms, specific embodiments will be exemplified and described in detail below. However, it should be understood that this is not intended to limit the present invention to the specific disclosed form, and includes all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

<Method for producing cement additives>

Cement compositions have a problem of significantly deteriorating workability due to hardening through a hydration reaction when a certain amount of time elapses after the addition of water, and in the case of conventional additives used to prevent such deterioration in water-reducing properties, there is a problem in that only limited performance realized at a specific molecular weight is expressed due to a narrow molecular weight distribution. Accordingly, the present inventors have developed a method for preparing a cement additive that can further improve the workability and strength of cement by improving the water reducing properties of the cement composition and reducing the rapid slump loss at the same time by having a wide molecular weight distribution.

A method for producing a cement additive according to an embodiment of the present invention includes adding a monomer mixture and a first polymerization initiator to a reactor; preparing a copolymer by adding a second polymerization initiator while raising the temperature inside the reactor to 85 to 95 °C; and neutralizing by adding a neutralizer solution to a reactor containing the prepared copolymer.

The polymerization reaction is initiated by the addition of the first polymerization initiator, and then the temperature of the reactor is raised to 85 to 95 ° C. to control the molecular weight of the polycarboxylic acid-based additive to be prepared, thereby manufacturing an additive having a molecular weight distribution in a wide and diverse range. When the temperature raising step is not performed separately, an additive having a very narrow molecular weight distribution is produced, and when added to a cement composition, there is a problem in that a rapid slump loss occurs or water reducing properties are not expressed. In addition, when the temperature increase set temperature is less than 85 ° C., sufficient additional polymerization may not be initiated, so expected performance may not be expressed, and if it exceeds 95 ° C., polymerization stability may be lowered, and the solvent vaporizes to cause a change in the concentration of the monomer mixture, resulting in a non-uniform reaction.

In addition, by adding the second polymerization initiator together with the temperature increase after the addition of the first polymerization initiator, the concentration of the initiator (together with the first polymerization initiator) is increased in the reactant, so that a large amount of active radicals can be generated at a rapid rate. Accordingly, a copolymer having a wider molecular weight distribution can be prepared by producing a polymer with a constant and high molecular weight.

The monomer mixture and the first polymerization initiator may be separately added to the reactor for the same period of time. In this case, as the first polymerization initiator is added at a constant concentration and at a uniform rate, polymerization of the simultaneously introduced monomer mixture may be immediately initiated to produce a polymer having a uniform distribution. This is preferable because it is possible to control the weight average molecular weight of the copolymer.

The heating step may be heated at a constant rate to the above-described target temperature range (85 to 95 ° C.), and the temperature raising time is not particularly limited, but is, for example, 1 to 6 hours, preferably 3 to 5 hours. Can be carried out.

The types of the first polymerization initiator and the second polymerization initiator may be the same or different, and the specific type is not particularly limited. When polymerization is performed using water as a solvent, a water-soluble polymerization initiator such as ammonium or alkali metal persulfate or hydrogen peroxide may be used.

Further, in the polymerization using lower alcohols, aromatic hydrocarbons, aliphatic hydrocarbons, ester compounds or ketone compounds as solvents, hydroperoxides such as benzoyl peroxide, lauroyl peroxide cumene hydroperoxide, and aromatic azo compounds such as azobisisobutyronitrile may be used as polymerization initiators, and these may be used alone or in combination. At this time, an accelerator such as an amine compound may be used in combination.

In addition, in the case of using a water-lower alcohol mixed solvent, it may be appropriately selected from among the various polymerization initiators or combinations of polymerization initiators and accelerators.

The amount of the first polymerization initiator may be included in 0.5 to 1.0 parts by weight, preferably 0.7 to 0.9 parts by weight, based on dry weight, based on 100 parts by weight of the monomer mixture. When included within the above content range, the polymerization reaction can be performed at a uniform rate to realize stable polymerization reactivity, and thus, a high conversion rate can be implemented.

The content of the second polymerization initiator may be included in 0.05 to 0.5 parts by weight, preferably 0.1 to 0.3 parts by weight, based on 100 parts by weight of the monomer mixture. When included within the above content range, it is possible to stably produce a polymer having a constant and high molecular weight, and thus, it is possible to prepare a copolymer having a wide molecular weight distribution.

In the method for producing a cement additive according to an embodiment of the present invention, the temperature of the initial reactor to which the monomer mixture and the first polymerization initiator are added may be 70 to 75 ° C. before the temperature raising step, the polymerization reaction may be partially initiated within the above temperature range, and the polymerization reaction may be performed more stably under reaction conditions using a water-soluble polymerization initiator as a solvent.

In the method for producing a cement additive according to an embodiment of the present invention, after the addition of the second polymerization initiator, the step of reducing the temperature of the reactor to 75 to 80 °C may be included. By including the step of reducing the temperature to the above temperature range, it is possible to suppress the activity of a large amount of active radicals generated through the addition of the second polymerization initiator, and as a result, it is possible to obtain a molecular weight distribution of a desired level by reducing the rate of polymerization reaction.

In the method for preparing a cement additive according to an embodiment of the present invention, before adding the monomer mixture and the first polymerization initiator, a third polymerization initiator may be further included in the reactor. In this case, the polymerization reaction is actively performed simultaneously with the introduction of the monomer compound in the presence of sufficient active radicals before the introduction of the monomer compound, thereby increasing the molecular weight distribution of the copolymer.

The third polymerization initiator may be the same as the first polymerization initiator and the second polymerization initiator.

The amount of the third polymerization initiator may be included in 0.1 to 0.5 parts by weight, preferably 0.1 to 0.3 parts by weight, based on 100 parts by weight of the monomer mixture. When included within the above content range, it is possible to realize optimal polymerization activity, resulting in excellent economic feasibility.

A method for producing a cement additive according to an embodiment of the present invention may include the steps of including a third polymerization initiator in an initial reactor, then including a first polymerization initiator in a reactor to which a monomer mixture is added, and copolymerizing with a second polymerization initiator while raising the temperature inside the reactor to 85 to 95, which includes the polymerization initiator before, during, and during the temperature rise of the copolymerization reaction, in which case the best water-reducing properties, fluidity over time, and strength characteristics are obtained. It is desirable to be able to implement

The monomer mixture includes an (alkoxy)polyalkylene glycol mono(meth)acrylic acid ester-based monomer and a (meth)acrylic acid-based monomer.

The (alkoxy) polyalkylene glycol mono (meth) acrylate monomers include methoxy polyethylene glycol mono (meth) acrylate, methoxy polypropylene glycol mono (meth) acrylate, methoxy polybutylene glycol mono (meth) acrylate, methoxy polyethylene glycol polypropylene glycol mono (meth) acrylate, methoxy polyethylene glycol polybutylene glycol mono (meth) acrylate, methoxy polypropylene glycol polybutylene. Glycol mono(meth)acrylate, methoxypolyethylene glycol polypropylene glycol polybutylene glycol mono(meth)acrylate, ethoxypolyethylene glycol mono(meth)acrylate, ethoxypolypropylene glycol mono(meth)acrylate, ethoxypolybutylene glycol mono(meth)acrylate, ethoxypolyethylene glycol polypropylene glycol mono(meth)acrylate, ethoxypolyethylene glycol polybutylene glycol mono It may be at least one selected from the group consisting of no (meth) acrylate, ethoxypolypropylene glycol polybutylene glycol mono (meth) acrylate, or ethoxy polyethylene glycol polypropylene glycol polybutylene glycol mono (meth) acrylate, but is not limited thereto.

The (alkoxy) polyalkylene glycol mono(meth)acrylate-based monomer may be included in 75 to 95 parts by weight, preferably, 80 to 90 parts by weight based on 100 parts by weight of the monomer mixture. When included in the above content range, it is possible to implement high strength at an early stage by improving the initial water-reducing properties.

The (meth)acrylic acid-based monomer may be at least one selected from the group consisting of acrylic acid, methacrylic acid, and monovalent metal salts, divalent metal salts, ammonium salts, and organic amine salts of these acids, but is not limited thereto.

In addition, the (meth)acrylic acid-based monomer may be included in 5 to 25 parts by weight, preferably, 10 to 15 parts by weight based on 100 parts by weight of the monomer mixture. When included within the above content range, a certain level of workability may be realized by preventing slump loss.

The monomer mixture may further include an additional monomer in addition to the above-described (alkoxy) polyalkylene glycol mono(meth)acrylate-based monomer and the (meth)acrylic acid-based monomer, for example, a (meth)acrylic acid ester-based monomer. It may further include, but is not limited thereto.

The (meth)acrylic acid ester-based monomer may be at least one selected from the group consisting of 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, and monovalent metal salts, divalent metal salts, ammonium salts, and organic amine salts thereof, but is not limited thereto.

In the method for preparing a cement additive according to an embodiment of the present invention, a thiol-based chain transfer agent may be further included to control molecular weight.

The thiol-based chain transfer agent used at this time may be at least one material selected from the group consisting of mercaptoethanol, thioglycerol, thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thiomalic acid, octyl thioglycolate, and octyl 3-mercaptopropionic acid.

Specifically, the amount of the thiol-based chain transfer agent may be 0.01 to 5 parts by weight based on 100 parts by weight of the monomer mixture.

In the method for producing a cement additive according to an embodiment of the present invention, a step of adding an ethanolamine-based or alkyldiethanolamine-based neutralizer solution to a reactor containing the prepared copolymer is neutralized, and the polycarboxylic acid-based copolymer salt thus prepared is used as a main component of the cement additive.

The neutralizing agent solution may be at least one selected from the group consisting of ethanolamine, diethanolamine, triethanolamine, methyldiethanolamine, ethyldiethanolamine and butyldiethanolamine.

The cement additive according to one embodiment of the present invention may have a weight average molecular weight of 33,000 to 38,000 and a polydispersity index (PDI) of 2.3 to 2.7.

The polydispersity index is the weight average molecular weight (Mw) divided by the number average molecular weight (Mn), which means that the molecular weight distribution is narrow and wide. When the cement additive has only a small molecular weight, when applied to the cement composition, water reducing properties are lowered and only retention properties can be highly expressed.

According to the manufacturing method of the present invention, by preparing a cement additive through a stable polymerization reaction under the above-described process conditions, the weight average molecular weight and polydispersity index value within the above range are satisfied, and thus both water reducing properties and slump retention properties of the additive can be improved.

<Cement composition>

In the present invention, a cement composition containing a cement additive prepared according to the above method is provided, and even after a certain period of time has elapsed after being mixed with water by the cement additive, appropriate fluidity can be maintained by the additive, so that it has very good workability and at the same time has excellent strength characteristics.

The cement composition according to one embodiment of the present invention may contain 0.001 to 5 parts by weight of the aforementioned cement additive, preferably 0.003 to 0.1 parts by weight, based on 100 parts by weight of cement. The cement composition according to the present invention can significantly reduce slump loss and improve strength even with the use of a small amount of additives. When included in less than 0.001 parts by weight, it is difficult to implement the desired effect in a small amount, and when it exceeds 5 parts by weight, there is a problem in that economic efficiency is lowered because the effect is not implemented as much as the added amount.

The cement composition includes all cement compositions known in the art, including cement paste prepared by adding water to the cement, mortar prepared by adding fine aggregate sand thereto, and concrete prepared by additionally adding and mixing coarse aggregate gravel thereto.

Hereinafter, the operation and effect of the invention will be described in more detail through specific examples of the invention. However, this is presented as an example of the invention, and thereby the scope of the invention is not limited in any sense.

Example and comparative example

Example 1 - Preparation of additives

200 g of water was injected into a 2 L capacity glass reactor equipped with a thermometer, stirrer, dropping funnel, nitrogen inlet tube and reflux condenser, and the inside of the reaction vessel was purged with nitrogen under stirring and heated to 75° C. under a nitrogen atmosphere.

It was prepared by adding 20 g of ammonium persulfate at a concentration of 3.5 wt % as a polymerization initiator (third polymerization initiator) to the reactor, and then allowing it to completely dissolve.

In a separate beaker, 300 g of methoxy polyethylene glycol monomethacrylate (average added mole number of ethylene oxide (EO): 45 moles) (A), 25 g of acrylic acid, 25 g of methacrylic acid, 2.5 g of 2-mercapto ethanol and 50 g of water were mixed and mixed for 30 minutes with a stirrer to prepare a polymerization mixture.

The prepared polymerization mixture and the polymerization initiator (first polymerization initiator) were added dropwise to each of the prepared polymerization mixture and 80 g of an aqueous solution of ammonium persulfate having a concentration of 3.5 wt% for 4 hours at a constant rate.

After completion of the dropping, the temperature inside the reactor was raised at a constant rate to 90°C. At the same time as the temperature was raised, 10 g of an aqueous solution of ammonium persulfate having a concentration of 3.5 wt% as a polymerization initiator (second polymerization initiator) was additionally introduced into the reactor.

Thereafter, the temperature inside the reactor was lowered to 80° C., cooled for 1 hour, and then neutralized using 30 wt% aqueous sodium hydroxide solution for 1 hour to prepare a cement additive.

Example and comparative example

As shown in Table 1 below, additives were prepared in the same manner as in Example 1, except that the amount and time of introduction of the polymerization initiator and whether or not the temperature was raised after the addition of the first polymerization initiator was changed.

division
(parts by weight)* polymerization initiator Temperature rise* Third polymerization initiator First polymerization initiator Second polymerization initiator Example 1 0.2 0.8 0.1 ○ Example 2 0.2 0.8 0.2 ○ Example 3 0.2 0.8 0.3 ○ Comparative Example 1 0.2 0.8 0.2 X Comparative Example 2 0.2 0.8 0.4 X Comparative Example 3 0.2 0.8 - X Part by weight is the content with respect to 100 parts by weight of the monomer mixture
Whether or not the temperature is raised means whether or not the temperature is raised to 85 to 95 ° C. after adding the first polymerization initiator

Experiment method

1. Analysis of physical properties of additives

For the additives prepared according to Examples and Comparative Examples, the weight average molecular weight and polydispersity index (PDI) values measured by GPC (Gel Permeation Chromatography) are shown in Table 2 below.

division Weight average molecular weight (Mw) PDI Example 1 33,000 2.4 Example 2 34,000 2.6 Example 3 36,000 2.5 Comparative Example 1 32,000 1.9 Comparative Example 2 35,000 2.1 Comparative Example 3 30,000 1.8

2. concrete test

Concrete was prepared by kneading 3.53 kg of ordinary Portland cement (Ssangyong Cement), 7.94 kg of sand (standard sand), 10.01 kg of crushed stone, 1.66 kg of water (water supply) and 14.12 g of cement additives (based on 50% solid content) according to Examples and Comparative Examples. Each manufactured concrete was measured for slump and compressive strength according to Korean Industrial Standards KSF 2402 and KSF 2449, and the results are shown in Table 3.

division Concrete slump (mm) Compressive strength (MPa) Early after 60 minutes 1 day 7 days Example 1 210 200 16 23 Example 2 220 215 19 27 Example 3 220 205 17 24 Comparative Example 1 200 180 14 18 Comparative Example 2 205 185 13 20 Comparative Example 3 200 175 13 17

As can be seen from Table 3, when the additive according to the present invention was used, compared to the comparative example, it was confirmed that the slump loss was significantly smaller over time and the compressive strength was excellent.

In the case of Comparative Example 3 in which no additional polymerization initiator was added during the additional heating process and the heating process, it was confirmed that the molecular weight distribution was the narrowest, the slump loss was large, and the compressive strength was significantly lowered compared to Examples.

Claims (16)

adding a monomer mixture including a (alkoxy)polyalkylene glycol mono(meth)acrylic acid ester-based monomer and a (meth)acrylic acid-based monomer and a first polymerization initiator to a reactor;
preparing a copolymer by adding a second polymerization initiator while raising the temperature inside the reactor to 85 to 95 °C; and
Including; neutralizing by adding a neutralizer solution to a reactor containing the prepared copolymer,
The neutralizing agent solution comprises at least one selected from the group consisting of ethanolamine, diethanolamine, triethanolamine, methyldiethanolamine, ethyldiethanolamine and butyldiethanolamine.
According to claim 1,
After adding the second polymerization initiator, reducing the temperature of the reactor to 75 to 80 ° C.
According to claim 1,
Wherein the first polymerization initiator and the second polymerization initiator are each independently at least one selected from the group consisting of ammonium persulfate, magnesium persulfate, sodium persulfate and hydrogen persulfate.
According to claim 1,
The first polymerization initiator is included in 0.5 to 1.0 parts by weight based on 100 parts by weight of the monomer mixture, a method for producing a cement additive.
According to claim 1,
The second polymerization initiator is included in 0.05 to 0.5 parts by weight based on 100 parts by weight of the monomer mixture, a method for producing a cement additive.
According to claim 1,
Before adding the monomer mixture and the first polymerization initiator, a third polymerization initiator is further included in the reactor.
According to claim 6,
Wherein the third polymerization initiator is at least one member selected from the group consisting of ammonium persulfate, magnesium persulfate, sodium persulfate and hydrogen persulfate.
According to claim 6,
The third polymerization initiator is included in 0.1 to 0.5 parts by weight based on 100 parts by weight of the monomer mixture, method for producing a cement additive.
According to claim 1,
The (alkoxy) polyalkylene glycol mono(meth)acrylic acid ester monomers include methoxypolyethylene glycol mono(meth)acrylate, methoxypolypropylene glycol mono(meth)acrylate, methoxypolybutylene glycol mono(meth)acrylate, methoxypolyethylene glycol polypropylene glycol mono(meth)acrylate, methoxypolyethylene glycol polybutylene glycol mono(meth)acrylate, methoxypolypropylene glycol polybutyl Len glycol mono(meth)acrylate, methoxypolyethylene glycol polypropylene glycol polybutylene glycol mono(meth)acrylate, ethoxypolyethylene glycol mono(meth)acrylate, ethoxypolypropylene glycol mono(meth)acrylate, ethoxypolybutylene glycol mono(meth)acrylate, ethoxypolyethylene glycol polypropylene glycol mono(meth)acrylate, ethoxypolyethylene glycol polybutylene glycol A method for producing a cement additive comprising at least one selected from the group consisting of mono(meth)acrylate, ethoxypolypropylene glycol polybutylene glycol mono(meth)acrylate, and ethoxypolyethylene glycol polypropylene glycol polybutylene glycol mono(meth)acrylate.
According to claim 1,
The (meth)acrylic acid-based monomer is at least one selected from the group consisting of acrylic acid, methacrylic acid, and monovalent metal salts, divalent metal salts, ammonium salts, and organic amine salts of these acids.
According to claim 1,
The monomer mixture further comprises at least one (meth)acrylic acid ester-based monomer selected from the group consisting of 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, and monovalent metal salts, divalent metal salts, ammonium salts, and organic amine salts thereof.
delete According to claim 1,
Method for producing a cement additive, further comprising a thiol-based chain transfer agent in the copolymerization step.
According to claim 1,
The method of producing a cement additive having a weight average molecular weight of 33,000 to 38,000.
According to claim 1,
The method of producing a cement additive, wherein the cement additive has a polydispersity index (PDI) of 2.3 to 2.7.
A cement composition comprising 0.001 to 5 parts by weight of a cement additive prepared according to claim 1, based on 100 parts by weight of cement.