JP2015086197A - Method for producing esterified product, method for producing polymer, and use of the polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an esterified product of which the high-molecular-weight polymer content is extremely low.SOLUTION: The method for producing the esterified product, which is shown by general formula (1)(on condition that Ris a 1-30C hydrocarbon group; RO is a 2-18C oxyalkylene group and it does not matter if the repeating units of the RO are the same or different from one another but when the RO is a mixture of two or more kinds, it does not matter if the repeating units of the RO are added to one another in a block or random state; Ris a hydrogen atom or a methyl group; n is an average addition molar number of the oxyalkylene group and an integer of 0-300), comprises the steps of: performing an esterification reaction of the alcohol, which is shown by general formula (2) (on condition that Ris the same as defined in the general formula (1); RO is the same as defined in the general formula (1); n is the same as defined in the general formula (1)), with (meth)acrylic acid in a dehydration solvent; and distilling the dehydration solvent in the presence of a water-soluble polymerization inhibitor having the function of inhibiting a polymerization reaction in the absence of oxygen.

Description

  The present invention relates to a method for producing an esterified product, a method for producing a polymer, and a use of the polymer. More specifically, a method for producing a high-purity esterified product capable of suppressing the production of a product resulting from an esterification reaction between an alcohol and (meth) acrylic acid and a high molecular weight polymer of a dimer or higher of the raw material, The present invention relates to a method for producing a polymer and the use of the polymer.

  From the viewpoint of solubility, water-soluble polymers are, for example, detergent compositions, scale inhibitors, various inorganic and organic dispersants, thickeners, pressure-sensitive adhesives, adhesives, surface coating agents, cross-linking agents, and humectants. It is widely used for various applications such as.

  Among them, various (meth) acrylic acid esters (also simply referred to as “esterified products” in the present specification) obtained by esterifying alcohol and (meth) acrylic acid are used as monomer components. Polymers obtained by polymerization reaction are used in various applications such as cement dispersants. In such an esterification reaction, reaction product water is by-produced at the same time. Therefore, if this reaction product water is not removed from the reaction system (that is, if the reaction product water accumulates), the reaction proceeds in the direction of producing an esterified product due to the equilibrium reaction. It will not progress. Therefore, when synthesizing the esterified product, a dehydrated solvent is used, and this and the reaction product water are distilled (azeotropically), and the reaction product water is separated and removed, and the dehydrated solvent is refluxed to carry out the reaction. Furthermore, the target esterified product is obtained by distilling off the dehydrated solvent by azeotropy with water after completion of the reaction. Then, a polymerization reaction is carried out using the obtained esterified product as a monomer component to produce a desired polymer component.

  In the production process of the esterified product, a high molecular weight polymer (hereinafter, also simply referred to as “high molecular weight material”) of a dimer or more of a raw material or a product can be generated. However, when the obtained esterified product contains a high molecular weight substance, there is a problem that separation and purification becomes difficult. Furthermore, when a polymer obtained by polymerizing an esterified product containing a high molecular weight substance as a monomer component is used as, for example, a cement dispersant or a pigment dispersant, the physical properties of the final product may be adversely affected.

  Therefore, conventionally, in the process of producing an esterified product, a polymerization inhibitor that dissolves in the dehydrating solvent to be used is added during the esterification reaction, and a water-soluble polymerization inhibitor is added when the dehydrated solvent is distilled off. The formation of molecular weight was suppressed. More specifically, when the dehydrated solvent after the esterification reaction is distilled off by azeotropy with water, the resulting esterified product dissolves in water, so that a water-soluble polymerization inhibitor (specifically, hydroquinone) It has been considered that adding sufficient amount of is extremely useful for suppressing the formation of a high molecular weight product.

  On the other hand, Patent Literature 1 uses a polymerization inhibitor (more specifically, phenothiazine) that is easily dissolved in a dehydrating solvent during the esterification reaction as a polymerization inhibitor, and a water-soluble polymerization inhibitor when the dehydrating solvent is distilled off. A technique for producing an esterified product without adding (or using a very small amount of a water-soluble polymerization inhibitor) is disclosed.

JP 2000-154247 A

  According to the disclosure of Patent Document 1, it is said that the formation of a high molecular weight body can be suppressed without using a water-soluble polymerization inhibitor when the dehydrating solvent is distilled off.

  However, when the present inventor examined the esterified product produced by the method disclosed in Patent Document 1 in detail, it was found that a high molecular weight product was actually produced, although it was slight.

  Therefore, an object of the present invention is to polymerize (meth) acrylic acid, a product esterified product or a mixture thereof contained in an esterified product obtained by performing an esterification reaction of alcohol and (meth) acrylic acid. An object of the present invention is to provide a method for producing an esterified product having a very low content of a high-molecular-weight dimer or higher.

  Another object of the present invention is to provide a method for producing a polymer having a very low content of a high molecular weight polymer capable of lowering the physical properties of the final product, and a use of the polymer obtained by the method.

  As a result of intensive studies to solve the above problems, the present inventor has obtained a dehydrating solvent in the presence of a polymerization inhibitor that is water-soluble and has a function of inhibiting the polymerization reaction in the absence of oxygen. It has been found that the formation of a high molecular weight product can be effectively suppressed by distilling off and thus the present invention has been completed.

  That is, the above object of the present invention is achieved by the following configuration.

  1. General formula (2) in the presence of an acid catalyst in a dehydrating solvent

(However, R ¹ represents a hydrocarbon group having 1 to 30 carbon atoms, and R ² O represents an oxyalkylene group having 2 to 18 carbon atoms. In this case, the repeating units of each R ² O were the same. Or when R ² O is in the form of a mixture of two or more, each R ² O repeating unit may be added in blocks or randomly. And n represents the average number of moles added of the oxyalkylene group and is a number from 0 to 300).
After the esterification reaction between the alcohol represented by (meth) acrylic acid,
Including a step of distilling off the dehydrated solvent in the presence of a water-soluble polymerization inhibitor having a function of inhibiting a polymerization reaction in the absence of oxygen.

(However, R ¹ represents a hydrocarbon group having 1 to 30 carbon atoms, and R ² O represents an oxyalkylene group having 2 to 18 carbon atoms. In this case, the repeating units of each R ² O were the same. Or when R ² O is in the form of a mixture of two or more, each R ² O repeating unit may be added in blocks or randomly. R ³ is a hydrogen atom or a methyl group, and n represents the average number of moles added of the oxyalkylene group and is a number from 0 to 300.
A process for producing an esterified product represented by:
2. 1. The esterification reaction is performed in the presence of the water-soluble polymerization inhibitor. A process for producing an esterified product of
3. The water-soluble polymerization inhibitor is added to the reaction system after the esterification reaction. A process for producing an esterified product of
4). The water-soluble polymerization inhibitor is 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl or 1,4-naphthohydroquinone-2-sulfonic acid ammonium salt. ~ 3. A process for producing any esterified product of
5. After the esterification reaction between the alcohol represented by the general formula (2) and (meth) acrylic acid in a dehydrating solvent in the presence of an acid catalyst,
In the presence of a water-soluble polymerization inhibitor having a function of inhibiting the polymerization reaction in the absence of oxygen, the dehydrated solvent is distilled off to produce an esterified product represented by the above general formula (1),
A method for producing a polymer, comprising a step of polymerizing a monomer component containing the esterified product and an unsaturated carboxylic acid monomer;
6). 5. above. A cement dispersant comprising a polymer obtained by the method described in 1.

  According to the present invention, the raw material alcohol and (meth) acrylic acid, the product esterified product, or a mixture thereof, contained in the esterified product obtained by performing an esterification reaction between alcohol and (meth) acrylic acid, Provided is a method for producing an esterified product having a very low content of a high-molecular-weight dimer or higher produced by polymerization.

  In addition, according to the present invention, there are provided a method for producing a polymer having a very low content of a high molecular weight polymer capable of lowering the physical properties of the final product, and a use of the polymer obtained by the method.

  In a first aspect of the present invention, an alcohol represented by the above general formula (2) (also simply referred to as “alcohol” in the present specification) and (meth) acrylic acid in a dehydrating solvent in the presence of an acid catalyst In the above general formula (1), the method comprises the step of distilling off the dehydrating solvent in the presence of a water-soluble polymerization inhibitor having a function of inhibiting the polymerization reaction in the absence of oxygen. It is a manufacturing method of the esterified product shown.

  In the method for producing an esterified product of the present invention, the dehydrating solvent distilling step performed after the esterification reaction step is a water-soluble polymerization inhibitor having a function of inhibiting the polymerization reaction in the absence of oxygen (in the present specification, It is characterized in that it is carried out in the presence of simply “water-soluble polymerization inhibitor”.

In the present specification, “having a function of inhibiting the polymerization reaction in the absence of oxygen” means the following. First, a solution is prepared at room temperature (25 ° C.) so that the polymerization inhibitor has a concentration of 200 × 10 ⁻⁶ g / g (200 ppm) in acrylic acid not containing a stabilizer. When 5 ml of prepared acrylic acid is collected in a test tube and heated under the condition of 100 ° C. ± 0.5 ° C. in a nitrogen atmosphere, the time until polymerization of acrylic acid starts is 50 hours or more. Sometimes, the polymerization inhibitor is “has a function of inhibiting the polymerization reaction in the absence of oxygen”. The polymerization start of acrylic acid is regarded as the polymerization start when the temperature of the prepared solution rises by 1 ° C. from the temperature controlled within 100 ° C. ± 0.5 ° C. Moreover, the above-mentioned “under nitrogen atmosphere” indicates a state in which the liquid (5 ml of liquid) is sealed after bubbling with nitrogen at 300 mL / min for 3 minutes.

  Further, in the present specification, “water-soluble” means that the solubility of the polymerization inhibitor in water is 1 g / 100 mL or more at 25 ° C.

  As described above, conventionally, when an esterified product is produced, a polymerization inhibitor that dissolves in a dehydrated solvent (that is, dissolves in an organic solvent) is added during the esterification reaction in order to suppress the formation of a high molecular weight product. At the time of distilling off the dehydrated solvent, a water-soluble polymerization inhibitor was added to suppress the formation of a high molecular weight product. Moreover, in patent document 1, by utilizing that the polymerization inhibitor added at the time of an esterification reaction can function effectively also at the time of distillation of a dehydration solvent, by reducing the addition amount of a water-soluble polymerization inhibitor as much as possible. Discloses that the formation of high molecular weight is suppressed.

  However, as a result of detailed examination of the method for producing the esterified product, the present inventor has found that even with the technique of Patent Document 1, a high molecular weight product is produced even though the amount is small. . Therefore, the present inventor has further studied for the purpose of suppressing the production of high molecular weight, and when a specific polymerization inhibitor is present in the dehydrating solvent distillation step, the effect of suppressing the formation of high molecular weight is effective. Based on this finding, the present invention has been completed.

  In the production method of the esterified product represented by the general formula (1), various polymerization inhibitors have been conventionally used during the esterification reaction and, when necessary, when the dehydrating solvent is distilled off. The inventors newly paid attention to the ability of the polymerization inhibitor to inhibit polymerization in the absence of oxygen. As a result of examining in more detail the relationship between the properties of the polymerization inhibitor and the amount of high molecular weight product formed, the water solubility of the polymerization inhibitor used when the dehydrated solvent was distilled off and the ability to inhibit polymerization in the absence of oxygen were obtained. It was found that the amount of high molecular weight product produced can be effectively suppressed by specifying

  In addition, since the esterified product obtained by the production method of the present invention has a very small content of the high molecular weight substance, when the polymerization reaction is carried out using the esterified product as a raw material, the resulting polymer also contains the high molecular weight substance. A very small amount of polymer is obtained. Furthermore, it became clear that it is suitable for various uses (especially the use as a dispersing agent) by reducing content of such high molecular weight polymer.

  Embodiments of the present invention will be described below. In addition, although the structural requirement of this invention, embodiment, etc. are demonstrated in detail below, these are examples of the embodiment of this invention, and are not limited to these content.

<Esterified product>
First, the esterified product represented by the following general formula (1) produced by the production method of the present invention will be described below.

In the general formula (1), R ¹ represents a hydrocarbon group having 1 to 30 carbon atoms. When R ¹ is a hydrocarbon group having more than 30 carbon atoms, the water solubility of the copolymer obtained by copolymerizing the esterified product with, for example, (meth) acrylic acid is decreased, For example, the cement dispersion performance is lowered. The preferred range of R ¹ varies depending on the application. For example, when used as a raw material for a cement dispersant, R ¹ is a linear or branched alkyl group or aryl group having 1 to 18 carbon atoms. Is preferred. Specific examples of R ¹ include, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, tert-butyl group, pentyl group, hexyl group, octyl group, nonyl group, 2- Alkyl groups such as ethylhexyl group, decyl group, dodecyl group, undecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, eicosyl group, heneicosyl group, docosyl group; phenyl group, etc. Examples include aryl groups; alkylphenyl groups such as benzyl group and nonylphenyl group; cycloalkyl groups such as cyclohexyl group; alkenyl groups; alkynyl groups. Among these, when used as a raw material for a cement dispersant, as described above, a methyl group, an ethyl group, a propyl group, a butyl group, and a phenyl group are preferable.

R ² O is an oxyalkylene group having 2 to 18 carbon atoms, preferably 2 to 8 carbon atoms. When R ² O is an oxyalkylene group having more than 18 carbon atoms, the water-solubility of the copolymer obtained by copolymerizing the esterified product with, for example, (meth) acrylic acid is lowered, and the use performance For example, cement dispersion performance and the like are reduced. Examples of R ² O include an oxyethylene group, an oxypropylene group, an oxybutylene group, and an oxystyrene group, and among these, an oxyethylene group, an oxypropylene group, and an oxybutylene group are preferable. Further, the repeating units of R ² O may be the same or different. Among these, when the repeating units of R ² O are different, that is, when two or more different repeating units are included, the repeating units of each R ² O may be added in blocks or randomly. It may be.

R ³ is a hydrogen atom or a methyl group. When a polymer produced using the esterified product is used as a raw material for a cement dispersant, an esterified product in which R ³ is a hydrogen atom and an esterified product in which R ³ is a methyl group are mixed in an appropriate ratio, etc. It is also possible to use either one of them or only one of them.

Furthermore, n is a number from 0 to 300 and represents the average number of moles added of repeating units of R ² O (oxyalkylene group). When n exceeds 300, when the esterified product is copolymerized with, for example, (meth) acrylic acid, the polymerizability is lowered. The average added mole number n also varies depending on the intended use of the esterified product obtained by the esterification reaction. For example, when used as a raw material for a cement dispersant, the average added mole number n is preferably a number of 5 to 200, more preferably 8 to 150. Moreover, when using as a thickener etc., the average addition mole number n has the preferable number of 10-250, More preferably, it is 50-200.

When n = 0, the above R ¹ is carbon due to difficulty in synthesizing the esterified product (for example, production conditions are extremely limited from the viewpoint of solubility in water and boiling point). A hydrocarbon group having 4 or more atoms is preferred. That is, when n = 0 in the general formula (1), the raw material (that is, the alcohol represented by the general formula (2)) is preferably a high boiling point such as butanol when the esterified product is synthesized. By using such an alcohol, the alcohol is prevented from evaporating with the produced water, and further, the alcohol is also prevented from dissolving in the produced water. Therefore, a part of the alcohol raw material remains outside the system. It is possible to suppress a decrease in the yield of the esterified product due to leaving.

  According to the production method of the present invention described in detail below, the raw material alcohol, (meth) acrylic acid, and the product contained in the esterified product obtained by performing an esterification reaction of alcohol and (meth) acrylic acid An esterified product having a very low content of a dimer or higher molecular weight product formed by polymerization of the esterified product or a mixture thereof can be obtained.

  In the present specification, “the content of the high molecular weight substance in the esterified product (in the present specification, also simply referred to as“ the content of the high molecular weight ””) is the area of the measurement peak portion of the target esterified product. On the other hand, the ratio of the area of the measurement peak portion of the high molecular weight substance detected other than the measurement peak portion of the target esterified product is expressed. Specifically, the method measured in the Example mentioned later shall be employ | adopted.

  The content of the high molecular weight substance in the esterified product is preferably 0.5% or less, more preferably 0.4% or less, and particularly preferably 0.3% or less. In addition, the minimum of the content rate of a high molecular weight body is 0%. When the content of the high molecular weight substance in the esterified product is 0.5% or less, the esterified product is used (particularly used by polymerization), for example, in addition to a cement dispersant, calcium carbonate, Basic performances of pigment dispersants such as carbon black and ink, scale inhibitors, gypsum / water slurry dispersants, CWM dispersants, thickeners and the like can be improved. In particular, when intended for use in a cement dispersant, cement dispersion performance and slump retention performance can be improved.

<< Production Method of Esterification >>
Next, a method for producing an esterified product, which is a characteristic element of the present invention, will be described in detail.

  The production method of the esterified product of the present invention is represented by the general formula (2)

(However, since R ¹ , R ² O and n have the same definition as in the general formula (1), the description thereof is omitted)
An esterified product is obtained by performing an esterification reaction of the alcohol represented by (meth) acrylic acid. According to the production method of the present invention, the content of the high molecular weight polymer of dimer or higher produced by polymerization of (meth) acrylic acid, product esterified product or a mixture thereof contained in the obtained esterified product is An extremely low esterified product can be obtained. The “high molecular weight product formation rate (or content rate)” used in the present specification is measured under the measurement conditions and methods described in the examples, and adopts a calculated value.

  The production method of the esterified product of the present invention is mainly divided into (I) esterification reaction step, (II) acid catalyst neutralization step, and (III) dehydrating solvent distillation step. It is essential to perform the leaving step in the presence of a water-soluble polymerization inhibitor having a function of inhibiting the polymerization reaction in the absence of oxygen. In addition, the process (II) can be performed arbitrarily as needed.

  Therefore, as long as the predetermined water-soluble polymerization inhibitor is added to the system (in the reactor) at the time of the dehydrating solvent distillation step, the water-soluble polymerization inhibitor may be added at any stage.

  For example, the water-soluble polymerization inhibitor may be added to the system (inside the reactor) at the time of the esterification reaction. That is, the esterification reaction may be performed in the presence of the water-soluble polymerization inhibitor. When the water-soluble polymerization inhibitor and the raw material for the esterification reaction (alcohol and (meth) acrylic acid) are introduced into the reaction system at the same time, the effect of suppressing the formation of a high molecular weight substance is high, and operability is also improved. To preferred.

  Further, the water-soluble polymerization inhibitor may be added to the reaction system after the esterification reaction. More specifically, the water-soluble polymerization inhibitor may be added after the esterification reaction and before the dehydrating solvent distillation step.

  Furthermore, a water-soluble polymerization inhibitor may be added both before the start of the reaction in the esterification reaction step and before the dehydrating solvent distillation step. However, in this embodiment, since the number of times of adding the water-soluble polymerization inhibitor is increased, it is inferior to the above two forms from the viewpoint of operability and economy.

  Hereinafter, (I) the esterification reaction step, (II) the acid catalyst neutralization step, and (III) the dehydrated solvent distillation step will be described.

(I) Esterification Reaction Step In the esterification reaction step, an esterification reaction between the alcohol represented by the general formula (2) and (meth) acrylic acid is performed in a dehydrating solvent in the presence of an acid catalyst.

  Specifically, first, the reaction system (reaction vessel or reactor) is charged with the alcohol of the general formula (2) and (meth) acrylic acid, acid catalyst, dehydrating solvent and a polymerization inhibitor as necessary. Then, the esterification reaction is performed until the mixture reaches a predetermined esterification rate at a predetermined temperature.

(alcohol)
The alcohol raw material that can be used for the ester reaction is a compound represented by the general formula (2).

The alcohol raw material represented by the general formula (2) may be used alone or in the form of a mixture of two or more. The form in which the alcohol raw material represented by the general formula (2) is used in a mixture of two or more types is not particularly limited, and two or more types of mixtures in which at least one of R ¹ , R ² O or n is different. As long as it is used in Among them, preferably (a) when R ¹ is composed of two kinds of a methyl group and a butyl group, (b) when R ² O is composed of two kinds of an oxyethylene group and an oxypropylene group, (C) The case where n is composed of two types of 1 to 10 and 11 to 100, and a combination of (a) to (c) as appropriate.

((Meth) acrylic acid)
Regarding (meth) acrylic acid that can be used for the ester reaction, acrylic acid and methacrylic acid may be used alone or in combination, and the mixing ratio may be in any range. Can be adopted.

  The mixing ratio of the raw materials used in the esterification reaction is stoichiometrically 1: 1 (molar ratio), but in practice, the esterification reaction of alcohol and (meth) acrylic acid is efficient. It is not particularly limited as long as it proceeds, and usually from the viewpoint of using one raw material in excess to speed up the esterification reaction and purifying the desired esterified product, more easily distilled off, It is preferable to use excessively low-boiling raw materials. Further, in the present invention, when the reaction product water and the dehydrating solvent are azeotroped during the esterification reaction, a part of the low-boiling point (meth) acrylic acid is distilled out and taken out of the reaction system. It is preferable to add the use amount (preparation amount) of (meth) acrylic acid to the amount (preparation amount) in excess of the stoichiometrically calculated amount. Specifically, the amount of (meth) acrylic acid used is usually 1.0 to 30 mol, preferably 1.2 to 10 mol, per 1 mol of alcohol. By making the usage-amount of (meth) acrylic acid 1.0 mol or more with respect to 1 mol of alcohol, an esterification reaction can be advanced smoothly and the yield of the target esterified product is made sufficiently high. be able to. On the other hand, when the amount is 30 mol or less, a sufficient yield can be obtained, and (meth) acrylic acid is not used in a large amount, which is economically preferable. Furthermore, when the amount of (meth) acrylic acid used is excessive (over 1.0 mol) with respect to 1 mol of alcohol, unreacted (meth) acrylic acid remains. Accordingly, since a mixture of the esterified product and the (meth) acrylic acid mixture can be obtained, the mixture can be used for the copolymerization reaction as it is. Therefore, the polymer used for the dispersant and the like can be synthesized efficiently.

(Acid catalyst)
In the esterification reaction of the present invention, the esterification reaction is performed in the presence of an acid catalyst. By performing the reaction in the presence of an acid catalyst, the reaction can be rapidly advanced. As the acid catalyst that can be used in the esterification reaction of the present invention, conventionally known acid catalysts can be used. For example, sulfuric acid, methanesulfonic acid, paratoluenesulfonic acid, paratoluenesulfonic acid hydrate, xylene Sulfonic acid, xylene sulfonic acid hydrate, naphthalene sulfonic acid, naphthalene sulfonic acid hydrate, trifluoromethane sulfonic acid, "Nafion" resin, "Amberlyst 15" resin, phosphotungstic acid, phosphotungstic acid hydrate, hydrochloric acid, etc. Of these, sulfuric acid, paratoluenesulfonic acid, paratoluenesulfonic acid hydrate, methanesulfonic acid and the like are preferably used. Furthermore, the present inventor has shown that one of the causes of the formation of an impurity diester that causes deterioration of the quality and performance of the esterified product is due to the cleavage of the alcohol raw material, and that the cleavage can also be caused by an acid catalyst. I knew it. Based on this finding, the present inventors have found that an acid catalyst that is difficult to cleave is more desirable. Specific examples of the acid catalyst include p-toluenesulfonic acid and p-toluenesulfonic acid hydrate.

  The amount of the acid catalyst used is not particularly limited as long as the desired catalytic action can be effectively expressed. For example, it is 0.4 meq / g or less, preferably 0.36. -0.01 meq / g, more preferably 0.32-0.05 meq / g. By setting it within the above range, for example, when the obtained esterified product is used for the production of a cement dispersant, it is possible to effectively suppress the formation of a high molecular weight polymer capable of reducing the dispersion performance and the thickening property.

More specifically, when the amount of the acid catalyst used is 0.4 meq / g or less, the amount of diester formed in the reaction system during the esterification reaction can be reduced. As a result, it is possible to suppress a decrease in application performance such as a cement dispersant synthesized using the obtained esterified product, for example, cement dispersibility. Here, the usage amount (milli equivalent / g) of the acid catalyst is the total charge amount (g) of alcohol and (meth) acrylic acid as raw materials, based on the number of H ⁺ equivalents (milli equivalent) of the acid catalyst used in the reaction. ) Divided by. More specifically, it is a value calculated by the following mathematical formula (1).

  The method for adding the acid catalyst to the reaction system may be added all at once, may be added continuously, or may be added sequentially, but in terms of workability, together with the raw materials It is preferable to charge the reactor all at once.

(Polymerization inhibitor)
In the esterification reaction step, the reaction is preferably performed in the presence of a polymerization inhibitor. By using a polymerization inhibitor, polymerization of raw material alcohol and (meth) acrylic acid, a product esterified product, or a mixture thereof can be prevented, and the production of a high molecular weight product is suppressed, which is preferable.

  Therefore, in the esterification reaction step, the predetermined water-soluble polymerization inhibitor used in the dehydration solvent step may be added, other polymerization inhibitors may be added, or both of these may be added. Also good. “Other polymerization inhibitors” include (i) a polymerization inhibitor that is not water-soluble and does not have the ability to inhibit the polymerization reaction in the absence of oxygen (or has a very low inhibition ability), (ii) A polymerization inhibitor that is not water-soluble and has the ability to inhibit the polymerization reaction in the absence of oxygen; (iii) water-soluble but does not have the ability to inhibit (or inhibit) the polymerization reaction in the absence of oxygen. 3 types of polymerization inhibitors are included. The (iii) polymerization inhibitor is a water-soluble polymerization inhibitor that is an essential element in the dehydrating solvent distillation step in the present invention in terms of the ability to inhibit the polymerization reaction in the absence of oxygen. Clearly distinguished. Among these, it is preferable that the polymerization inhibitor (ii) is added in the esterification reaction step. By using the polymerization inhibitor (ii) at the time of the esterification reaction, the polymerization inhibitor also functions at the time of distilling off the dehydrating solvent. Therefore, together with the water-soluble polymerization inhibitor used in the dehydrating agent distilling step, Generation of molecular weight can be more effectively suppressed. In the esterification reaction step, it is preferable that not only the polymerization inhibitor (ii) but also a water-soluble polymerization inhibitor used in the dehydrating solvent step is further added. Thus, by using two kinds of polymerization inhibitors, it is possible to more effectively suppress the formation of a high molecular weight product.

  On the other hand, when the water-soluble polymerization inhibitor essential for the dehydrating solvent distillation step is already added at this step, the polymerization inhibitors (i) to (iii) may not be added. Even in the above case, it is a matter of course that the polymerization inhibitors (i) to (iii) may be added (that is, they may be used in combination).

  As the polymerization inhibitors (i) to (iii) that can be used in the esterification reaction, known polymerization inhibitors can be used and are not particularly limited. For example, phenothiazine, tri-p-nitrophenylmethyl, di-p-fluorophenylamine, diphenylpicrylhydrazyl, N- (3-N-oxyanilino-1,3-dimethylbutylidene) aniline oxide, benzoquinone, hydroquinone, Examples include methoquinone, butylcatechol, nitrosobenzene, picric acid, dithiobenzoyl disulfide, cuperone, and copper (II) chloride. One of these polymerization inhibitors may be used alone, or two or more thereof may be used in combination.

  Among the above polymerization inhibitors, the polymerization inhibitors added during the esterification reaction are phenothiazine (corresponding to (ii) above) and hydroquinone (corresponding to (iii) above) because of the solubility of dehydrating solvent and generated water. , Methoquinone (corresponding to the above (iii)) is preferable, and phenothiazine is particularly preferable. These polymerization inhibitors are extremely useful from the viewpoint of effectively suppressing the formation of a high molecular weight substance because they can exhibit the ability to inhibit polymerization even in the dehydrating solvent distillation step performed after the completion of the esterification reaction.

  The amount of the polymerization inhibitor used is in the range of 0.001 to 1% by weight, preferably 0.001 to 0.1% by weight, based on the total charge of alcohol and (meth) acrylic acid as raw materials. Preferably there is. In addition, when using a some polymerization inhibitor, it is preferable in these total amounts being in the said range.

  By making the use amount of the polymerization inhibitor 0.001% by weight or more, the polymerization inhibition ability can be sufficiently expressed, alcohol as a raw material, (meth) acrylic acid, esterified product as a product or these Polymerization of the mixture can be effectively prevented. On the other hand, when the amount of the polymerization inhibitor used is 1% by weight or less, the amount of the polymerization inhibitor remaining in the esterified product, which is a product, can be reduced, which is preferable in terms of quality and performance. Further, even if it exceeds 1% by weight, it is difficult to obtain further effects commensurate with this. Accordingly, if it is 1% by weight or less, it is not necessary to add a large amount of a polymerization inhibitor, which is preferable from an economical viewpoint.

(Dehydrated solvent)
Furthermore, the esterification reaction of the present invention is an esterification reaction in a dehydrating solvent. In the present specification, the dehydrated solvent is defined as a solvent azeotropic with water. That is, by using a dehydrating solvent, the reaction product water produced by the esterification reaction can be efficiently azeotroped. Examples of the dehydrating solvent include benzene, toluene, xylene, cyclohexane, dioxane, pentane, hexane, heptane, chlorobenzene, isopropyl ether, etc., and these may be used alone or as a mixed solvent. Can do. Among these, those having an azeotropic temperature with water of 150 ° C. or lower, more preferably in the range of 60 to 100 ° C. are preferable. Specifically, xylene, cyclohexane, toluene, dioxane, benzene, isopropyl ether, hexane, heptane Etc. Use of water having an azeotropic temperature of 150 ° C. or lower is preferable from the viewpoint of operability such as temperature control in the reaction system during the reaction and control of condensate liquefaction treatment of the azeotrope.

  The dehydrated solvent is desirably azeotroped with the reaction product water outside the reaction system, and the reaction product water is condensed and liquefied and refluxed while being separated and removed. At this time, the amount of the dehydrated solvent used is the alcohol and the raw material. It is in the range of 1 to 100% by weight, preferably 2 to 50% by weight, based on the total charge of (meth) acrylic acid. By making the amount of the dehydrating solvent used 1% by weight or more, the reaction product water generated during the esterification reaction can be sufficiently removed from the reaction system by azeotropy, and the esterification equilibrium reaction easily proceeds. Therefore, it is preferable. On the other hand, even if the amount of the dehydrated solvent used exceeds 100% by weight, it is difficult to obtain further effects commensurate with this. Therefore, the smaller the amount of dehydrated solvent used, the smaller the amount of heat required to keep the reaction temperature constant. Therefore, if the amount of dehydrated solvent used is 100% by weight or less, it is effective and economical. This is preferable in terms of both viewpoints.

  In the present invention, the esterification reaction step can be carried out either batchwise (batch type) or continuously, but is preferably carried out batchwise.

  The reaction conditions in the esterification reaction may be any conditions that allow the esterification reaction to proceed smoothly. For example, the reaction temperature is 30 to 140 ° C, preferably 60 to 130 ° C, more preferably 90 to 125 ° C, Especially preferably, it is 100-120 degreeC. These are general (in a broad sense) conditions for the esterification reaction of the present invention, and the above-described dehydrated solvent is azeotroped with the reaction product water, while the reaction product water is condensed and liquefied while being separated and removed. In the case of refluxing, it is an example, and it is included in these ranges, but is not completely consistent.

  By setting the reaction temperature to 30 ° C. or higher, the dehydrated solvent can be sufficiently refluxed, the time required for dehydration can be shortened, and the esterification reaction easily proceeds, which is preferable. In addition, it is preferable to set the reaction temperature to 140 ° C. or lower because the production of diester and the polymerization of the raw material due to the cleavage of the alcohol raw material can be suppressed. The reaction time is not particularly limited, and it is preferably continued until the esterification rate reaches at least 70%, preferably at least 80%, as will be described later. Usually, it is 1 to 50 hours, preferably 3 to 40 hours. It is. Furthermore, the esterification reaction according to the present invention may be carried out under normal pressure or under reduced pressure, but it is desirable to carry out under normal pressure from the viewpoint of equipment.

  The esterification rate in the esterification reaction according to the present invention is preferably 70% or more, more preferably 70 to 99%, and most preferably 80 to 98%. If the esterification rate is 70% or more, the performance (for example, cement dispersibility, etc.) of the polymer produced using the obtained esterified product, such as cement dispersant, is reduced. It can be sufficiently suppressed. The “esterification rate” used in this specification is measured under the measurement conditions / method described in the examples, and a calculated value is adopted.

(II) Acid Catalyst Neutralization Step In the esterification reaction step (I) above, when an ester reaction is performed in the presence of an acid catalyst, it is desirable to perform a neutralization step described below.

  If the acid catalyst remains in the esterified product, after the esterification reaction step, when water is added in the dehydrating solvent distilling step described in detail below to azeotrope, or for further polymerization using the esterified product In addition, when an aqueous solution of an esterified product produced by adding adjusted water after the ester reaction is produced, hydrolysis of the esterified product by an acid catalyst may occur. As a result, the quality and performance of the esterified product are deteriorated, and what is generated by hydrolysis (also simply referred to as “hydrolyzed product” in this specification) remains in the esterified product. Then, when the polymer used for various dispersants such as cement dispersants and thickeners is synthesized using the esterified product, the hydrolysis product becomes an impurity not involved in the polymerization, and the polymerization rate ( As a result, the productivity is reduced, and the quality and performance of the polymer are deteriorated. Therefore, it is desirable to carry out the neutralization step of the acid catalyst.

  As the neutralization method of the acid catalyst, a conventionally known method can be adopted as long as it does not hydrolyze the produced esterified product. However, an alkaline aqueous solution is added and neutralized at an appropriate temperature and time. preferable.

The alkaline aqueous solution used in the neutralization step is not particularly limited and can be prepared by dissolving in water and using an alkaline substance. Examples of the alkaline substance include a hydroxide of M (OH) _m . Examples thereof include carbonates and phosphates of alkali metals and alkaline earth metals, ammonia, and amines. M in this case represents an alkali metal, an alkaline earth metal, or an ammonium group, and the value of “m” is determined by the type of M. Therefore, specific examples of the alkaline substance include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkaline earth metal hydroxides such as magnesium hydroxide and calcium hydroxide, and sodium carbonate. And alkali metal carbonates such as sodium hydrogen carbonate, potassium carbonate and potassium hydrogen carbonate, ammonia and amines. In the case of producing a cement dispersant using an esterified product, it is preferable to use an alkali metal or alkaline earth metal hydroxide, carbonate, phosphate, etc. More preferably sodium hydroxide and potassium hydroxide. In the present invention, these alkaline substances may be used alone or in combination of two or more at an appropriate ratio.

  The neutralization temperature is not particularly limited, but is preferably 90 ° C. or lower. By setting the neutralization temperature to 90 ° C. or less, it is possible to suppress the production of a large amount of hydrolysis products caused by the added alkaline aqueous solution acting as a hydrolysis catalyst.

  In the present invention, the neutralization time in the neutralization treatment step is not particularly limited as long as it can neutralize part of the acid catalyst, preferably the acid catalyst and (meth) acrylic acid. Although it varies depending on the type and amount of the catalyst and (meth) acrylic acid, the neutralization time is usually 10 hours or less. From the viewpoint of productivity, it is preferably 8 hours or shorter, more preferably 7 hours or shorter, and particularly preferably 6 hours or shorter.

(III) Dehydrating solvent distillation step In the method for producing an esterified product of the present invention, since the esterification reaction is carried out in a dehydrating solvent (solvent), the esterification reaction is carried out in the esterification reaction step (I) above. The dehydrated solvent is distilled off from the reaction solution. Further, in the step (I), when the esterification reaction is carried out in the presence of an acid catalyst, the esterification reaction is carried out in the esterification reaction step (I) above, and then the acid catalyst (II) above. In the neutralization step, the acid catalyst and further a part of (meth) acrylic acid are neutralized, and then the dehydrating solvent is distilled off from the reaction solution.

  The first aspect of the present invention is characterized in that the dehydrating solvent distillation step is performed in the presence of a water-soluble polymerization inhibitor having a function of inhibiting the polymerization reaction in the absence of oxygen.

  The definition of the “water-soluble polymerization inhibitor having a function of inhibiting the polymerization reaction in the absence of oxygen” used as essential in the dehydrating solvent distillation step is as described above. When evaluated using acrylic acid under the conditions, it is preferable that the time until the polymerization of acrylic acid starts is 50 hours or more, more preferably 100 hours or more. The upper limit is not particularly limited. Further, the water solubility is preferably 1 g / 100 mL or more, more preferably 10 g / 100 mL or more, with respect to water at 25 ° C. The upper limit is not particularly limited, but is, for example, 1000 g / 100 mL.

  As long as the above conditions are satisfied, the water-soluble polymerization inhibitor used in this step is not particularly limited. Among them, 4-hydroxy group is from the viewpoint of availability and the ability to inhibit the polymerization reaction in the absence of oxygen. -2,2,6,6-tetramethylpiperidine-1-oxyl (also referred to herein as "4H-TEMPO"), 1,4-naphthohydroquinone-2-sulfonic acid ammonium salt (Kawasaki Chemical Co., Ltd.) Product name: Kinopower QS-W10) is preferably used. In addition, a water-soluble polymerization inhibitor may be used individually by 1 type, or may be used in combination of 2 or more type. Among the water-soluble polymerization inhibitors, it is more preferable to use 4H-TEMPO that has a high ability to inhibit a polymerization reaction in the absence of oxygen and can suppress the formation of a high molecular weight product.

  The amount of the water-soluble polymerization inhibitor used is in the range of 0.001 to 1% by weight, preferably 0.001 to 0.1% by weight, based on the total charge of alcohol and (meth) acrylic acid as raw materials. It is preferable to be within. In addition, when using a some polymerization inhibitor, it is preferable in these total amounts being in the said range.

  By making the use amount of the water-soluble polymerization inhibitor 0.001% by weight or more, the polymerization inhibition ability can be sufficiently expressed, and alcohol as a raw material, (meth) acrylic acid, esterified product as a product or Polymerization of these mixtures can be effectively prevented. On the other hand, when the amount of the water-soluble polymerization inhibitor used is 1% by weight or less, the amount of the water-soluble polymerization inhibitor remaining in the esterified product can be reduced, which is preferable in terms of quality and performance. . Further, even if it exceeds 1% by weight, it is difficult to obtain further effects commensurate with this. Accordingly, if it is 1% by weight or less, it is not necessary to add a large amount of a water-soluble polymerization inhibitor, which is preferable from an economical viewpoint.

  The dehydrating solvent evaporating step is not particularly limited as long as it can distill off the dehydrated solvent, but a method of evaporating by heating is preferred. When the dehydrating solvent is distilled off, it may be carried out at normal pressure or under reduced pressure, but it is preferably carried out at normal pressure from the viewpoint of operability and economy.

  Further, the temperature at the start of the dehydration of the dehydrated solvent depends on the type of the dehydrated solvent and the ratio of the dehydrated solvent to water, but the temperature at the end of the destillation is preferably set to the boiling point of water ± 5 ° C. For example, when carried out at normal pressure, 100 ± 5 ° C. is preferable. By setting it as such a temperature range, a dehydrating solvent can be distilled off efficiently.

  The distillation time of the dehydrated solvent depends on the scale of the system, but is preferably 10 hours or less. From the viewpoint of productivity, it is preferably 8 hours or shorter, and more preferably 6 hours or shorter.

<Polymer>
The esterified product obtained by the above production method is copolymerized with an unsaturated carboxylic acid monomer to give a polymer used for various applications. That is, according to this invention, the polymer obtained by superposing | polymerizing the monomer component containing the esterification thing obtained by the said manufacturing method, and an unsaturated carboxylic acid-type monomer is also provided.

  Hereinafter, the polymer using the esterified product obtained by the production method of the present invention will be described.

  The polymer of the present invention is obtained using a monomer component containing an esterified product represented by the above general formula (1) and an unsaturated carboxylic acid monomer obtained by the production method described in detail above. It is characterized by that. As a result, as described above, the content of the high molecular weight crosslinked polymer with poor dispersion performance contained in the polymer is extremely low, and the basic performance is whatever it is used (especially blended and used as a main component). There is very little mixing of impurities that adversely affect the surface, and good dispersion performance can be imparted. In particular, when the polymer of the present invention is used as a cement dispersant, it can be said that it is extremely useful in that it can exhibit good cement dispersion performance and slump retention performance.

  The polymer of the present invention includes any of those obtained by polymerizing one or more of the above esterified products, and can be obtained by neutralizing with an alkaline substance as necessary. It contains a polymer salt.

  In addition, the weight average molecular weight of the polymer of the present invention (including the polymer salt) is appropriately determined in accordance with the intended use, and is suitable for use in, for example, a cement dispersant. Is preferably in the range of 500 to 300,000, particularly 5,000 to 200,000 in terms of polyethylene glycol by gel permeation chromatography (GPC). The value obtained by subtracting the peak top molecular weight from the weight average molecular weight of the polymer is preferably 0 to 8000, more preferably 0 to 7000. When the weight average molecular weight is 500 or more, the water reducing performance of the cement dispersant can be improved. On the other hand, by setting it to 300,000 or less, the water reducing performance and slump loss preventing ability of the cement dispersant can be improved. Further, when the value obtained by subtracting the peak top molecular weight from the weight average molecular weight is 8000 or less, the slump retention performance of the obtained cement dispersant can be improved.

<< Production Method of Polymer >>
Next, a method for producing a polymer using the esterified product obtained by the production method of the present invention will be described below.

  The method for producing a polymer of the present invention includes a step of polymerizing a monomer component containing an esterified product represented by the general formula (1) and an unsaturated carboxylic acid monomer. That is, in the second embodiment of the present invention, an esterification reaction between the alcohol represented by the general formula (2) and (meth) acrylic acid is performed in a dehydrating solvent in the presence of an acid catalyst, and then oxygen is added. In the presence of a water-soluble polymerization inhibitor having the function of inhibiting the polymerization reaction, the dehydrated solvent is distilled off to produce the esterified product represented by the general formula (1). It is a manufacturing method of a polymer including the process of superposing | polymerizing the monomer component containing a saturated carboxylic acid type monomer.

  The method for producing a polymer of the present invention can obtain polymers according to various uses by performing a polymerization reaction using the esterified product represented by the general formula (1) as a monomer component. As long as it is not particularly limited, for example, in the same manner as known methods such as those described in JP-B-59-18338, JP-A-9-86990 and JP-A-9-286645, Although it can use for a polymerization reaction with (meth) acrylic acid (salt) and the monomer copolymerizable with the monomer component of these esterification products as needed, it is not limited to these. Needless to say, conventionally known various polymerization methods can be applied.

  Specifically, for example, in the method for producing a polymer of the present invention, an esterified monomer represented by the general formula (1) (hereinafter also simply referred to as an esterified monomer) is converted into an unsaturated carboxylic acid. It can be obtained by a polymerization reaction with a system monomer and, if necessary, a monomer copolymerizable with these monomers.

  As unsaturated carboxylic acid monomers, acrylic acid, methacrylic acid, crotonic acid and their metal salts, ammonium salts, organic ammonium salts and other unsaturated monocarboxylic acid compounds, maleic acid, itaconic acid, citraconic acid, Examples thereof include fumaric acid or unsaturated dicarboxylic acid compounds such as metal salts, ammonium salts and organic ammonium salts thereof. Among these, acrylic acid, methacrylic acid or a salt thereof is preferable from the viewpoint of polymerizability, and acrylic acid or methacrylic acid is particularly preferable. In addition, only 1 type of these compounds may be used independently, and 2 or more types may be used together. Moreover, these compounds may use commercially available compounds, or may be prepared by synthesizing themselves.

  Here, in order to obtain a desired polymer, the esterified monomer component and the like may be copolymerized using a polymerization initiator. The copolymerization can be performed by a method such as polymerization in a solvent or bulk polymerization.

  Polymerization in a solvent can be carried out either batchwise or continuously. The solvent used here is water; lower alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol; benzene, toluene, xylene, cyclohexane, aromatic or aliphatic hydrocarbons such as n-hexane; ester compounds such as ethyl acetate; ketone compounds such as acetone and methyl ethyl ketone; From the solubility of the monomer component of the raw material esterified product and the resulting copolymer and the convenience when using the copolymer, it was selected from the group consisting of water and lower alcohols having 1 to 4 carbon atoms. It is preferable to use at least one kind. In that case, methyl alcohol, ethyl alcohol, isopropyl alcohol and the like are particularly effective among the lower alcohols having 1 to 4 carbon atoms.

  When polymerization is performed in an aqueous medium, a water-soluble polymerization initiator such as ammonium or alkali metal persulfate or hydrogen peroxide is used as the polymerization initiator. In this case, an accelerator such as sodium hydrogen sulfite or a molle salt can be used in combination. For polymerization using a lower alcohol, aromatic hydrocarbon, aliphatic hydrocarbon, ester compound or ketone compound as a solvent, peroxides such as benzoyl peroxide and lauroyl peroxide; hydroperoxides such as cumene hydroperoxide; azo An aromatic azo compound such as bisisobutyronitrile is used as a polymerization initiator. In this case, an accelerator such as an amine compound can be used in combination. Furthermore, when a water-lower alcohol mixed solvent is used, it can be appropriately selected from the above-mentioned various polymerization initiators or combinations of polymerization initiators and accelerators. The polymerization temperature is appropriately determined depending on the solvent to be used and the polymerization initiator, but is usually within a range of 0 to 120 ° C.

  Bulk polymerization uses a peroxide such as benzoyl peroxide or lauroyl peroxide as a polymerization initiator; a hydroperoxide such as cumene hydroperoxide; an aliphatic azo compound such as azobisisobutyronitrile, and the like. Performed within the temperature range.

In addition, a thiol chain transfer agent can be used in combination for adjusting the molecular weight of the obtained polymer. The thiol chain transfer agent used in this case is represented by the general formula HS-R ⁵ -E _g (wherein R ⁵ represents an alkyl group having 1 to 2 carbon atoms, and E represents —OH, —COOM ′, —COOR ⁶ or —SO ₃ M group, M ′ represents hydrogen, monovalent metal, divalent metal, ammonium group or organic amine group, R ⁶ represents an alkyl group having 1 to 10 carbon atoms, g Represents an integer of 1 to 2, for example, mercaptoethanol, thioglycerol, thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thiomalic acid, octyl thioglycolate, 3-mercapto Examples thereof include octyl propionate, and one or more of these can be used.

  The polymer thus obtained can be used as a main component in various applications as it is, but if necessary, the polymer salt obtained by neutralizing with an alkaline substance can be used for various applications such as a cement dispersant. It may be used as a main component. Preferred examples of such alkaline substances include inorganic substances such as hydroxides, chlorides and carbon salts of monovalent metals and divalent metals; ammonia; organic amines and the like.

  In the method for producing a polymer of the present invention, the esterified monomer component represented by the general formula (1) that can be used may be used alone or in combination of two or more. You may do it. In particular, when two or more types are used in combination, it is desirable to use a combination of different types of expression characteristics so that characteristics (function, performance, etc.) according to the intended use can be expressed. As an example, the following two types of combinations are advantageous when used as a cement dispersant.

That is, in the esterified product represented by the general formula (1), the average added mole number n represents an integer of 1 to 97, preferably 1 to 10. A first esterified product ^{(a 1)} represented by), the average addition mole number n is 4 to 100, preferably an integer of 11 to 100. ) Of the second esterified product (a ² ) (wherein the average added mole number of the second esterified product (a ² ) is the average added mole number of the first esterified product (a ¹ ). 3) or more) is advantageous.

The method for producing such a mixture of the first esterified product (a ¹ ) and the second esterified product (a ² ) is as described in the method for producing the esterified product. 2 esterified products (a ¹ ) and (a ² ) may be separately produced by an esterification reaction, or may be produced by an esterification reaction between a corresponding alcohol mixture and (meth) acrylic acid. In particular, the latter method can provide an industrially inexpensive production method.

In this case, the weight ratio of the first esterified product (a ¹ ) to the second esterified product (a ² ) is 5:95 to 95: 5, preferably 10:90 to 90:10.

Examples of the first esterified product (a ¹ ) include methoxy (poly) ethylene glycol mono (meth) acrylate, methoxy (poly) propylene glycol mono (meth) acrylate, methoxy (poly) butylene glycol mono (meth) acrylate, Methoxy (poly) ethylene glycol (poly) propylene glycol mono (meth) acrylate, methoxy (poly) ethylene glycol (poly) butylene glycol mono (meth) acrylate, methoxy (poly) propylene glycol (poly) butylene glycol mono (meth) acrylate , Methoxy (poly) ethylene glycol (poly) propylene glycol (poly) butylene glycol mono (meth) acrylate, ethoxy (poly) ethylene glycol mono (meth) acrylate, Xyl (poly) propylene glycol mono (meth) acrylate, ethoxy (poly) butylene glycol mono (meth) acrylate, ethoxy (poly) ethylene glycol (poly) propylene glycol mono (eta) acrylate, ethoxy (poly) ethylene glycol (poly) Examples include butylene glycol mono (meth) acrylate, ethoxy (poly) propylene glycol (poly) butylene glycol mono (meth) acrylate, ethoxy (poly) ethylene glycol (poly) propylene glycol (poly) butylene glycol mono (meth) acrylate, and the like. The It is important that the first esterified product (a ¹ ) has hydrophobicity in the side chain short-chain alcohol.

From the viewpoint of ease of copolymerization, the side chain preferably contains a large number of ethylene glycol units. Therefore, (a ¹ ) is preferably an (alkoxy) (poly) ethylene glycol mono (meth) acrylate having an average added mole number of 1 to 97, preferably 1 to 10.

Examples of the second esterified product (a ² ) include methoxypolyethylene glycol mono (meth) acrylate, methoxypolyethylene glycol (poly) propylene glycol mono (meth) acrylate, and methoxypolyethylene glycol (poly) butylene glycol mono (meth) acrylate. , Methoxypolyethylene glycol (poly) propylene glycol (poly) butylene glycol mono (meth) acrylate, ethoxy polyethylene glycol mono (meth) acrylate, ethoxy polyethylene glycol (poly) propylene glycol mono (meth) acrylate, ethoxy polyethylene glycol (poly) butylene Glycol mono (meth) acrylate, ethoxy polyethylene glycol (poly) propylene glycol (poly) Such as Chi glycol mono (meth) acrylate.

In order to obtain high water reduction, it is important to disperse the cement particles with steric repulsion due to alcohol chains having an average added mole number of the second esterified product (a ² ) of 4 to 100 and hydrophilicity. For that purpose, it is preferable that many oxyethylene groups are introduced into the polyalkylene glycol chain, and a polyethylene glycol chain is most preferable. Therefore, the average added mole number n of the alkylene glycol chain of the second esterified product (a ² ) is 4 to 100, preferably 11 to 100.

  Examples of the unsaturated carboxylic acid monomer that can be used in the method for producing the polymer of the present invention include acrylic acid, methacrylic acid, and monovalent metal salts, divalent metal salts of these acids, Examples thereof include (meth) acrylic acid (salt) monomers such as ammonium salts and organic amine salts, and one or more of these can be used.

In the production method of the polymer of the present invention, examples of the monomer that can be used as an esterified monomer and a monomer component of a (meth) acrylic acid (salt) monomer that can be used include: Dicarboxylic acids such as maleic acid, fumaric acid, citraconic acid, mesaconic acid, itaconic acid; these dicarboxylic acids and HO (R ¹¹ O) _r R ¹² (where R ¹¹ O is an oxyalkylene group having 2 to 4 carbon atoms) 1 or a mixture of two or more thereof, and in the case of two or more, they may be added in blocks or randomly, and r is the average number of moles of oxyalkylene groups added, represents an integer of ^{100, R 12} is mono- or diesters with an alcohol represented by) represents hydrogen or a 1 to 22 carbon atoms, preferably 1 to 15 alkyl group.; Unsaturated amides such as (meth) acrylamide and (meth) acrylic alkylamides; Vinyl esters such as vinyl acetate and vinyl propionate; Vinylsulfonic acid, (meth) allylsulfonic acid, sulfoethyl (meth) acrylate, 2-methylpropane Unsaturated sulfonic acids such as sulfonic acid (meth) acrylamide and styrene sulfonic acid, and their monovalent metal salts, divalent metal salts, aluminum salts, organic amine salts; aromatic vinyls such as styrene and α-methylstyrene; carbon Esters of phenyl group-containing alcohols such as aliphatic alcohols having 1 to 18 atoms, preferably 1 to 15 atoms or benzyl alcohol, and (meth) acrylic acid; polyalkylene glycol mono (meth) acrylates; polyalkylene glycol mono (meta) ) Allyl ether, monoa Examples include a ruxylene glycol mono (meth) acrylate, and one or more of these can be used.

《Use of polymer》
Next, the use of the polymer obtained by using the esterified product obtained by the production method of the present invention will be described below.

  Since the esterified product obtained by the production method of the present invention has a very small amount of a high molecular weight polymer, a high-purity polymer is produced without producing a high molecular weight polymer when a polymerization reaction is carried out using the esterified product as a raw material. Is obtained.

  Therefore, the polymer using the esterified product obtained by the production method of the present invention as a raw material is suitably used for various applications. For example, in addition to cement dispersants, calcium carbonate, carbon black, pigment dispersants such as ink, scale inhibitors, gypsum / water slurry dispersants, CWM dispersants, thickeners, etc. It is extremely useful as an esterified product as a raw material. That is, the esterified product obtained by the production method of the present invention is a cause of generating a high molecular weight polymer having poor dispersion performance, which causes adverse effects on the dispersion performance, which is the basic performance required for the above-mentioned applications. The amount of the high molecular weight substance is extremely small, and good dispersion performance can be exhibited. In particular, when used as a cement dispersant, it can exhibit good cement dispersion performance and slump retention performance.

  Therefore, the 3rd form of this invention is a cement dispersing agent containing the said polymer.

  The cement dispersant is at least the above-mentioned polymer; that is, in the esterified product represented by the above general formula (1) having a very low content of high molecular weight, n in the general formula (1) is a number of 1 to 300. It has the polymer obtained using the monomer component containing an esterification thing, It is characterized by the above-mentioned. Thereby, a favorable slump holding performance can be exhibited.

  Here, since the polymer shown above is as described above, the description thereof is omitted here.

  In addition to the polymer components defined above, the cement dispersant of the present invention includes conventionally known naphthalene cement dispersants, aminosulfonic acid cement dispersants, polycarboxylic acid cement dispersants, and lignin cements. At least one cement dispersant selected from the group consisting of dispersants may be blended. That is, in the cement dispersant of the present invention, the above polymer may be used alone, or if necessary, various components shown above and below can be blended in order to add value. Yes, these compounding compositions differ greatly depending on the presence or absence of the desired additional function. From those containing 100% by weight (total amount) or the main component of the polymer component, the polymer component is highly added. As the value component, there are various ways to add an appropriate amount to a conventional cement dispersant, and it cannot be uniquely defined.

  In addition to the conventionally known cement dispersants, the cement dispersant of the present invention includes air entraining agents, cement wetting agents, swelling agents, waterproofing agents, retarders, quick setting agents, water-soluble polymer substances, thickening agents. An agent, a flocculant, a drying shrinkage reducing agent, a strength enhancer, a curing accelerator, an antifoaming agent, and the like can be blended.

  The cement dispersant mainly composed of the polymer thus obtained promotes dispersion of the cement by being blended with a cement composition comprising at least cement and water.

  The cement dispersant of the present invention can be used for hydraulic cements such as Portland cement, high content of belite, alumina cement, various mixed cements, or hydraulic materials other than cement such as gypsum.

  Since the cement dispersant of the present invention has the above-described effects, it exhibits excellent effects even when added in a small amount as compared with conventional cement dispersants. For example, when used for mortar or concrete using hydraulic cement, 0.001 to 5%, preferably 0.01 to 1% of the cement weight may be added at the time of mixing. . By this addition, various preferable effects such as achievement of a high water reduction rate, improvement of slump loss prevention performance, reduction of unit water volume, increase of strength, and improvement of durability are brought about. When the addition amount is 0.001% or more, the performance can be sufficiently exhibited, and when it is 5% or less, a sufficient effect can be obtained with a small amount of the dispersant. Is advantageous.

  The cement dispersant of the present invention has a specific weight average molecular weight as described above, and a cement dispersant mainly composed of a polymer having a value obtained by subtracting the peak top molecular weight from the weight average molecular weight. It is desirable that

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. It is also possible to implement, and they are all included in the technical scope of the present invention. In the following production examples, “%” is based on weight unless otherwise specified, and “weight” and “mass” are synonymous unless otherwise noted. In addition, “−” in the table means that measurement / analysis is not performed, or that the indicated component is not used. Unless otherwise specified, measurements such as operation and physical properties were performed under conditions of room temperature (20 ° C.) / Relative humidity 40 to 50%.

<Manufacture of esterified product>
(Example 1-1)
1650 g of methoxypolyethylene glycol (n = 25) of a predetermined amount in a glass reactor (internal volume: 3 liters) equipped with a thermometer, a stirrer, a produced water separator, a reflux condenser tube as a condenser, and a nitrogen introduction tube, methacrylic acid (MAA) 474 g, 70% aqueous solution of paratoluenesulfonic acid monohydrate (PTS70) 67.2 g as esterification catalyst, 0.5 g of phenothiazine as a water-insoluble polymerization inhibitor and 106 g of cyclohexane as a dehydrating solvent are charged. The inside of the reactor was maintained at 110 to 120 ° C., and the esterification reaction was performed for 20 hours to obtain an esterification reaction liquid (1).

  The obtained esterification reaction liquid (1) was allowed to cool to 60 ° C. or less, and then 27 g of 49% sodium hydroxide aqueous solution as an aqueous alkali solution and water were added to neutralize the esterification catalyst, and then the absence of oxygen Then, 0.5 g of 1,4-naphthohydroquinone-2-sulfonic acid ammonium salt (Kinopower QS-W10, manufactured by Kawasaki Kasei Kogyo Co., Ltd.), which is a water-soluble polymerization inhibitor having an effect of inhibiting the polymerization reaction, was added and 105 The temperature was raised to 0 ° C., the dehydrated solvent was distilled off azeotropically with water, and adjusted water was added to obtain an aqueous monomer solution (1) composed of a mixture of the esterified product (1) and methacrylic acid. In Table 1, the production method of the esterified product by the above procedure is described as “Production Method 1”.

(Examples 1-2 and 1-3)
In Example 1-1, except that the raw materials used, the type of solvent (dehydration solvent) and the polymerization inhibitor, the amounts used, and the reaction temperature were changed as shown in Table 1, the examples Monomer aqueous solutions (2) and (3) were obtained in the same manner as in 1-1.

(Example 1-4)
Thermometer, stirrer, produced water separator, reflux condenser tube as condenser, 1700 g of methoxypolyethylene glycol (n = 10) in a predetermined amount in a glass reactor (internal volume: 3 liters), methacrylic acid (MAA) 697.5 g, paratoluenesulfonic acid hydrate 114.25 g which is an esterification catalyst, phenothiazine 0.5 g which is a water-insoluble polymerization inhibitor, and has an effect of inhibiting the polymerization reaction in the absence of oxygen A water-soluble polymerization inhibitor 4H-TEMPO (a reagent manufactured by Wako Pure Chemical Industries, Ltd.) 0.5 g and a dehydrating solvent cyclohexane 250 g were charged, and the reactor was maintained at 100 to 110 ° C. for 24 hours esterification reaction. To obtain an esterification reaction solution (4).

  The obtained esterification reaction liquid (4) was allowed to cool to 60 ° C. or lower, and 87.3 g of a 49% aqueous sodium hydroxide solution as an aqueous alkaline solution and water were added to neutralize the esterification catalyst. The temperature was raised, the dehydrated solvent was distilled off azeotropically with water, and adjusted water was added to obtain an aqueous monomer solution (4) comprising a mixture of the esterified product (2) and methacrylic acid. In Table 1, the production method of the esterified product by the above procedure is described as “Production method 2”.

(Examples 1-5 and 1-6)
In Example 1-4 above, except that the raw materials used, the type of solvent (dehydration solvent) and the polymerization inhibitor, the amounts used, and the reaction temperature were changed as shown in Table 1, the examples Monomer aqueous solutions (5) and (6) were obtained in the same manner as in 1-4.

(Example 1-7)
In Example 1-4, a monomer aqueous solution (7) was obtained in the same manner as Example 1-4, except that phenothiazine was not added during the esterification reaction step. In Table 1, the production method of the esterified product by the above procedure is described as “Production Method 3”.

(Comparative Example 1-1)
In Example 1-1, a comparative monomer aqueous solution (1) was obtained in the same manner as in Example 1-1 except that hydroquinone was used instead of kinopower after neutralization of the esterification catalyst.

(Comparative Example 1-2)
In Example 1-2, a comparative monomer aqueous solution (2) was obtained in the same manner as in Example 1-2, except that 4H-TEMPO was not added after neutralization of the esterification catalyst.

<< Analysis of esterification product >>
The esterification products produced in the above examples and comparative examples were measured under the following conditions and methods. The results are shown in Table 1.

(Analysis of esterification rate)
The esterification rate according to the esterified product obtained in the above Examples and Comparative Examples is the following esterification measurement conditions, from the ratio of the peak area of the esterified product and the peak area of the esterified alcohol, the following It is defined as a value calculated by Equation (2).

・ Measurement conditions for esterification rate Analysis device; Waters Alliance
Analysis software: Waters Empower Professional + GPC option Detector; Waters 410 RI detector Column used: GL Sciences Inert Sill ODS guard column + Inert Sill ODS-2 (inner diameter 4.6 mm × 250 mm) 3 Column temperature: 40 ° C.
Eluent: Solution adjusted to pH 4.0 by adding 30% NaOH aqueous solution to a mixture of acetonitrile / 100 mM acetate ion exchange aqueous solution = 40/60 (mass%) Flow rate: 0.6 ml / min.

(Analysis of the formation rate of high molecular weight)
The production rate of the high molecular weight compound contained in the esterified product obtained in the above Examples and Comparative Examples is detected in addition to the target esterified product with respect to the peak area of the target esterified product under the GPC measurement conditions shown below. It is defined as a value calculated by the following mathematical formula (3) from the ratio of the peak area of the high molecular weight product.

・ Measurement conditions of the production rate of high molecular weight body Analysis device; Waters Alliance (2695)
Analysis software; Waters, Empor professional + GPC option Detector; Waters 410RI detector Column: Tosoh Co., Ltd., TSK guard column SWXL + TSKgel G4000SWXL + G3000SWXL + G2000SWXL
Column temperature: 40 ° C
Eluent: A solution prepared by dissolving 115.6 g of sodium acetate trihydrate in a mixed solvent of 10999 g of water and 6001 g of acetonitrile, and further adjusting the pH to 6.0 with acetic acid Flow rate: 1.0 ml / min.

(Analysis of monomer concentration)
The monomer concentrations in the above examples and comparative examples are defined as values calculated by the following mathematical formula (4).

  The water concentration is an analytical value by the KF (Karl Fischer) method, and the p-toluenesulfonic acid salt concentration is a calculated value from the material balance.

  From Table 1 above, the production rate of high molecular weight can be reduced by performing the dehydrating solvent distillation step in the presence of a water-soluble polymerization inhibitor having a function of inhibiting the polymerization reaction in the absence of oxygen. confirmed. Furthermore, it was shown that the water-soluble polymerization inhibitor can further suppress the production of high molecular weight when added to the reactor during the esterification reaction.

<Production of polymer>
(Example 2-1)
Using the monomer solution (1) obtained in Example 1-1, copolymerization with (meth) acrylic acid as an unsaturated carboxylic acid monomer was performed, and a polycarboxylic acid copolymer ( A polymer (1)) was produced.

  Specifically, a predetermined amount of water is charged into a glass reaction vessel (internal volume: 2 liters) equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen introduction tube and a reflux condenser, and the reaction vessel is stirred with stirring. Was replaced with nitrogen and heated to 80 ° C. under a nitrogen atmosphere. Next, a monomer mixture aqueous solution obtained by uniformly mixing the monomer solution (1) obtained by the esterification reaction and 5.0 g of 3-mercaptopropionic acid, which is a chain transfer agent, for 4 hours and a predetermined amount An aqueous initiator solution (an aqueous solution containing 6.5 g of ammonium persulfate as an initiator and 150 g of water) was added dropwise over 5 hours. Thereafter, the temperature was maintained at 80 ° C. for 1 hour to complete the polymerization reaction. And it neutralized with 80 g of 49% sodium hydroxide aqueous solution as alkaline aqueous solution, and obtained the polycarboxylic acid copolymer (polymer (1)).

(Examples 2-2 to 2-7 and Comparative Examples 2-1 to 2-2)
In Example 2-1 above, except that the raw materials used, the types of solvents and polymerization inhibitors, and the amounts used thereof were changed as shown in Table 2, they were the same as in Example 2-1. Copolymers (2) to (7) and comparative polymers (1) to (2) were obtained, respectively.

<Evaluation of polymer>
The polycarboxylic acid copolymers produced in the above examples and comparative examples were measured under the following conditions and methods. The results are shown in Table 2.

(Weight average molecular weight)
The weight average molecular weights of the polymers obtained in the above Examples and Comparative Examples were determined under the GPC measurement conditions shown below in terms of polyethylene glycol.

GPC measurement condition analysis device; Waters Alliance (2695)
Analysis software; Waters, Empor professional + GPC option Detector; Waters 410RI detector Column: Tosoh Co., Ltd., TSK guard column SWXL + TSKgel G4000SWXL + G3000SWXL + G2000SWXL
Column temperature: 40 ° C
Eluent: A solution prepared by dissolving 115.6 g of sodium acetate trihydrate in a mixed solvent of 10999 g of water and 6001 g of acetonitrile, and further adjusting the pH to 6.0 with acetic acid Flow rate: 1.0 ml / min.

(Analysis of high molecular weight content)
The content of the high molecular weight substance contained in the polymers obtained in the above Examples and Comparative Examples is the sum of the main peak area of the polymer and the peak area of the high molecular weight substance under the GPC measurement conditions shown below. It is defined as a value calculated by the following mathematical formula (5) from the ratio of the peak area of the high molecular weight substance. The “peak area of the high molecular weight body” includes both the high molecular weight body contained in the esterified product and the high molecular weight product produced during the polymerization of the esterified product.

・ Measurement conditions of the production rate of high molecular weight body Analysis device; Waters Alliance (2695)
Analysis software; Waters, Empor professional + GPC option Detector; Waters 410RI detector Column: Tosoh Co., Ltd., TSK guard column SWXL + TSKgel G4000SWXL + G3000SWXL + G2000SWXL
Column temperature: 40 ° C
Eluent: A solution prepared by dissolving 115.6 g of sodium acetate trihydrate in a mixed solvent of 10999 g of water and 6001 g of acetonitrile, and further adjusting the pH to 6.0 with acetic acid Flow rate: 1.0 ml / min.

  From Table 2 above, it was shown that a polymer having a lower content of high molecular weight was obtained by producing a polymer (polycarboxylic acid copolymer) using the esterified product of the present invention.

<< Evaluation of cement dispersant >>
About the polycarboxylic acid copolymer manufactured in the said Example and comparative example, the concrete test was done on the following conditions, and the performance as a cement dispersing agent was evaluated. The results are shown in Table 3. In addition, “addition amount” in Table 3 means the blending amount (% by weight) of each polymer as a cement admixture with respect to the cement weight. The amount added was calculated as the non-volatile content of the admixture and expressed as weight percent.

(Concrete test conditions)
・ Concrete blending Unit amount Water: 172 kg / m ³ , cement (manufactured by Taiheiyo Cement: ordinary Portland cement): 382 kg / m ³ , coarse aggregate (Ome hard sandstone): 930 kg / m ³ , fine aggregate (Oigawa river sand ): 822 kg / m ³ , W / C = 45%, s / a = 47%.

  Under the above conditions, cement, fine aggregate and coarse aggregate are put into a 50 L forced-kneading mixer and kneaded for 10 seconds, then water containing the additive is added and kneaded for another 90 seconds to obtain concrete. Manufactured. The slump flow value and the amount of air of the obtained concrete were measured in accordance with Japanese Industrial Standard (JIS A1101, 1128, 6204). The results are shown in Table 3.

  From Table 3 above, it was shown that the polymer (polycarboxylic acid copolymer) produced using the esterified product of the present invention can be used as a cement dispersant excellent in slump retention performance. In particular, Test Examples (2), (4), and (6) had good slump retention, because the production of high molecular weight products was suppressed during the production of the esterified product as the polymer raw material. It is believed that there is.

Claims (6)

General formula (2) in the presence of an acid catalyst in a dehydrating solvent
(However, R ¹ represents a hydrocarbon group having 1 to 30 carbon atoms, and R ² O represents an oxyalkylene group having 2 to 18 carbon atoms. In this case, the repeating units of each R ² O were the same. Or when R ² O is in the form of a mixture of two or more, each R ² O repeating unit may be added in blocks or randomly. And n represents the average number of moles added of the oxyalkylene group and is a number from 0 to 300).
After the esterification reaction between the alcohol represented by (meth) acrylic acid,
Including a step of distilling off the dehydrated solvent in the presence of a water-soluble polymerization inhibitor having a function of inhibiting a polymerization reaction in the absence of oxygen.
(However, R ¹ represents a hydrocarbon group having 1 to 30 carbon atoms, and R ² O represents an oxyalkylene group having 2 to 18 carbon atoms. In this case, the repeating units of each R ² O were the same. Or when R ² O is in the form of a mixture of two or more, each R ² O repeating unit may be added in blocks or randomly. R ³ is a hydrogen atom or a methyl group, and n represents the average number of moles added of the oxyalkylene group and is a number from 0 to 300.
The manufacturing method of the esterified substance shown by these.   The method for producing an esterified product according to claim 1, wherein the esterification reaction is performed in the presence of the water-soluble polymerization inhibitor.   The method for producing an esterified product according to claim 1, wherein the water-soluble polymerization inhibitor is added to the reaction system after the esterification reaction.   The water-soluble polymerization inhibitor is 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl or 1,4-naphthohydroquinone-2-sulfonic acid ammonium salt according to claims 1 to 3. The manufacturing method of the esterified product of any one of Claims 1. General formula (2) in the presence of an acid catalyst in a dehydrating solvent
(However, R ¹ represents a hydrocarbon group having 1 to 30 carbon atoms, and R ² O represents an oxyalkylene group having 2 to 18 carbon atoms. In this case, the repeating units of each R ² O were the same. Or when R ² O is in the form of a mixture of two or more, each R ² O repeating unit may be added in blocks or randomly. And n represents the average number of moles added of the oxyalkylene group and is a number from 0 to 300).
After the esterification reaction between the alcohol represented by (meth) acrylic acid,
In the presence of a water-soluble polymerization inhibitor having the function of inhibiting the polymerization reaction in the absence of oxygen, the dehydrating solvent is distilled off to obtain the general formula (1)
(However, R ¹ represents a hydrocarbon group having 1 to 30 carbon atoms, and R ² O represents an oxyalkylene group having 2 to 18 carbon atoms. In this case, the repeating units of each R ² O were the same. Or when R ² O is in the form of a mixture of two or more, each R ² O repeating unit may be added in blocks or randomly. R ³ is a hydrogen atom or a methyl group, and n represents the average number of moles added of the oxyalkylene group and is a number from 0 to 300.
An esterified product represented by
The manufacturing method of a polymer including the process of superposing | polymerizing the monomer component containing the said esterification thing and an unsaturated carboxylic acid-type monomer.   A cement dispersant comprising a polymer obtained by the method according to claim 5.