JPH09309922A - Production of acrylic polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a biodegradable acrylic polymer having excellent chelating capacity at good efficiency by copolymerizing an acrylic monomer with a polymerization initiator being a specified peroxycarboxylic acid. SOLUTION: An acrylic monomer (e.g. acrylic acid or methacrylic acid) is copolymerized at a pH of 7 or below with a polymerization initiator being a peroxycarboxylic acid represented by formula I (wherein R<1> , R<2> and R<3> are each H or methyl, methyl, provided that it is desirable that all of them are H atoms or that anyone of them is methyl and the rest are H atoms). This peroxycarboxylic acid and an acrylic monomer represented by formula II (wherein X is H, an alkali metal or ammonium; and R<1> to R<3> are each H or methyl) are subjected to an aqueous solution polymerization at a pH of 7 or below in the presence of 1-10 wt. "/o, based on the entire weight of the polymerization system, strong acid, (e.g. sulfuric acid, oleum, perchloric acid, nitric acid, fluorosulfuric acid, an organic sulfonic acid or an acid which shows an acid dissociation index pKa of 3 or below in an aqueous solution) added to 25-75 wt. % hydrogen peroxide water to obtain an acrylic polymer.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an acrylic polymer. More specifically, the present invention relates to a method for efficiently producing an acrylic polymer having excellent chelating ability and biodegradability.

[0002]

2. Description of the Related Art Conventionally, in detergents containing a surfactant as a main component, the washing performance has been improved by incorporating a builder as an auxiliary component of the surfactant. As the builder, polymers of unsaturated aliphatic carboxylic acids such as polyacrylic acid, polymaleic acid and polyitaconic acid are used.

Polymers of these unsaturated aliphatic carboxylic acids have sufficient chelating ability but little biodegradability. By the way, these unsaturated aliphatic carboxylic acid polymers are polymerized by an aqueous solution polymerization method or the like. For example, acrylic acid has a very high polymerization activity and is easily polymerized, so it is possible to take a polymerization suppression method such as diluting it in a solvent used for the polymerization or blowing air as fine bubbles. Because of its large size, when polymerizing, add a polymerization initiator such as ammonium persulfate, first reduce the concentration of acrylic acid, and then add acrylic acid sequentially to temporarily generate heat of polymerization. There was a serious problem in industrialization, such as the need for measures such as prevention. Therefore,
Industrially, a method of neutralizing acrylic acid with caustic soda and the like and polymerizing it under alkaline conditions is adopted to obtain linear polyacrylic acid which is not biodegradable.

Further, Japanese Laid-Open Patent Publication No. 2-36210 discloses that
A mixture of unsaturated carboxylic acids such as acrylic acid and methacrylic acid with an ethylenically unsaturated double bond bonded through an ester group or an amide group and a specific monomer mixture having a COOX group is used as a polymerization initiator. Although a method of polymerizing by using is disclosed, it is necessary to polymerize a specific biodegradable monomer in advance, which is a step of at least two stages,
A more efficient manufacturing method is desired. The polymerization of this mixture is also carried out by neutralizing with caustic soda or the like and polymerizing under alkaline conditions.

Therefore, a method for efficiently producing an acrylic polymer having excellent chelating ability and biodegradability is desired.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for efficiently producing an acrylic polymer having excellent chelating ability and biodegradability under such circumstances. Is.

[0007]

As a result of intensive studies to achieve the above-mentioned object, the present inventor has found that the production can be efficiently carried out by a simple process using percarboxylic acid. The present invention has been completed based on such findings. That is, the present invention is as follows. (1) General formula (I)

[0008]

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[In the formula, R ¹ , R ² and R ³ represent a hydrogen atom or a methyl group. ] The manufacturing method of the acrylic polymer characterized by polymerizing an acrylic monomer at pH 7 or less using the percarboxylic acid represented by these as a polymerization initiator. (2) General formula (II) in the presence of hydrogen peroxide or hydrogen peroxide and a strong acid.

[0010]

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[In the formula, X is a hydrogen atom or an alkali metal atom.
Or an ammonium group, R¹, R ^TwoAnd R^ThreeIs hydrogen
Indicates an atom or a methyl group. ] Acrylic items represented by
Of water-soluble polymer while maintaining the pH of the polymerization system below 7
A method for producing an acrylic polymer, which comprises: (3) Formula (II) in an aqueous medium

[0012]

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[In the formula, X is a hydrogen atom or an alkali metal atom.
Or an ammonium group, R¹, R ^TwoAnd R^ThreeIs hydrogen
Indicates an atom or a methyl group. ] Acrylic items represented by
Treated with hydrogen peroxide or hydrogen peroxide and a strong acid, and then
Then, this treated product is treated with the same acrylic monomer or
Is mixed with another type of acrylic monomer represented by the general formula (II).
It is characterized by carrying out aqueous solution polymerization at pH 7 or less
A method for producing an acrylic polymer. (4) Generally in the presence of hydrogen peroxide or hydrogen peroxide and strong acid
Formula (II)

[0014]

Embedded image

[In the formula, X is a hydrogen atom or an alkali metal atom.
Or an ammonium group, R¹, R ^TwoAnd R^ThreeIs hydrogen
Indicates an atom or a methyl group. ] Acrylic items represented by
Mar and the general formula (III)

[0016]

[Chemical 12]

[In the formula, R ⁴ is a hydrogen atom, a methyl group, or -O.
H or -CH ₂ COOX, Y and Z are each a hydrogen atom, a chlorine atom, -COOX, -SO ₃ H, -OH, -O
COR ', - COR', - CONH 2 , or -CHO (X
Is a hydrogen atom, an alkali metal atom or an ammonium group,
R'represents an alkyl group having 1 to 12 carbon atoms. However, acrylic acid, methacrylic acid and crotonic acid are not included. ]
A method for producing an acrylic polymer, characterized in that the polymerizable unsaturated compound represented by the formula (3) is polymerized in an aqueous solution while keeping the pH of the polymerization system at 7 or less. (5) Formula (II) in an aqueous medium

[0018]

Embedded image

[In the formula, X is a hydrogen atom or an alkali metal atom.
Or an ammonium group, R¹, R ^TwoAnd R^ThreeIs hydrogen
Indicates an atom or a methyl group. ] Acrylic items represented by
Treated with hydrogen peroxide or hydrogen peroxide and a strong acid, and then
Then, this treated product is treated with the same acrylic monomer or
Is the same as another acrylic monomer represented by the general formula (II).
General formula (III)

[0020]

Embedded image

[In the formula, R ⁴ is a hydrogen atom, a methyl group, or -O.
H or -CH ₂ COOX, Y and Z are each a hydrogen atom, a chlorine atom, -COOX, -SO ₃ H, -OH, -O
COR ', - COR', - CONH 2 , or -CHO (X
Is a hydrogen atom, an alkali metal atom or an ammonium group,
R'represents an alkyl group having 1 to 12 carbon atoms. However, acrylic acid, methacrylic acid and crotonic acid are not included. ]
A method for producing an acrylic polymer, which comprises mixing a polymerizable unsaturated compound represented by the formula (3) and polymerizing the solution in an aqueous solution at a pH of 7 or less. (6) The number average molecular weight of the acrylic polymer is 300 to 10
The method for producing an acrylic polymer according to any one of (1) to (5) above, which is in the range of 10,000.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing an acrylic polymer according to the present invention has the general formula (I)

[0023]

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The present invention is characterized in that an acrylic monomer is polymerized at a pH of 7 or less using a percarboxylic acid represented by the formula as a polymerization initiator. In the formula, R ¹ , R ² and R ³ represent a hydrogen atom or a methyl group. Preferably, R ¹ , R ²
And R ³ are all hydrogen atoms or one of them is a methyl group and the rest are hydrogen atoms, and more preferably all are hydrogen atoms.

Examples of acrylic monomers include acrylic acid, methacrylic acid and crotonic acid, with acrylic acid and methacrylic acid being preferred. In order to obtain this percarboxylic acid, it is preferable to produce it by reacting an acrylic monomer from which the percarboxylic acid is obtained with hydrogen peroxide,
As the hydrogen peroxide, it is preferable to use 25 to 75% by weight of hydrogen peroxide solution, preferably 30 to 70% by weight of hydrogen peroxide solution.

It is preferable to add a strong acid to hydrogen peroxide in an amount of 1 to 10% by weight based on the total weight of the polymerization system. Strong acids include sulfuric acid, fuming sulfuric acid, perchloric acid, nitric acid, hydrochloric acid, fluorosulfuric acid,
Other than organic sulfonic acids, those having an acid dissociation index pKa of 3 or less in an aqueous solution system can be mentioned. As the organic sulfonic acid, benzenesulfonic acid, toluenesulfonic acid, sulfonic acid type ion exchange resin and the like are suitable. Of the above, sulfuric acid is particularly preferable.

As the polymerization method, the following (1) to
Representative examples of (4) are mentioned, but two or more kinds of acrylic monomers may be used, or a method in which these representative examples are combined may be adopted. As the polymerization method of (1),
In the presence of hydrogen peroxide or hydrogen peroxide and a strong acid, the general formula (II)

[0028]

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[In the formula, X is a hydrogen atom or an alkali metal atom.
Or an ammonium group, R¹, R ^TwoAnd R^ThreeIs hydrogen
Indicates an atom or a methyl group. ] Acrylic items represented by
The polymerization system at a pH of 7 or less, preferably 5 or less.
Method for producing acrylic polymer for water-soluble polymerization
It is. In this way, the acrylic monomer
Coexists with hydrogen peroxide and strong acid,
It is generated, and it is considered that this becomes a polymerization initiator.

The strong acid is as described above, and it is preferable that hydrogen peroxide and strong acid coexist. If the pH of the polymerization system exceeds 7, the desired acrylic polymer cannot be obtained. This polymerization reaction is usually 30 to 120 ° C, preferably 70 to 100 ° C.
It is better to carry out at a temperature in the range. Further, in this polymerization reaction, a water-soluble reducing agent can be used in combination with hydrogen peroxide as a polymerization initiator, if desired. Examples of the water-soluble reducing agent include ethylenediaminetetraacetic acid or its sodium salt or potassium salt, or iron and iron,
Complex compounds with heavy metals such as copper and chromium, sulfinic acid or its sodium salt or potassium salt, L-ascorbic acid or its sodium salt, potassium salt, calcium salt, ferrous pyrophosphate, ferrous sulfate, ferrous sulfate Ammonium iron, cobalt chloride, cobalt acetate, sodium sulfite,
Examples thereof include sodium acid sulfite, sodium formaldehyde sulfoxylate, and reducing sugars. These may be used alone or in combination of two or more. Of these, L-ascorbic acid and its sodium salt, potassium salt, and calcium salt are particularly preferable. At this time, the total weight of sulfuric acid or organic sulfonic acid is 0.1 to
You may add 10 weight%. As the organic sulfonic acid, benzenesulfonic acid, toluenesulfonic acid and sulfonic acid type ion exchange resin are suitable.

Further, this polymerization reaction may be carried out in the presence of a chain transfer agent, if desired. The type of the chain transfer agent is not particularly limited, and one or more can be arbitrarily selected from those conventionally used in aqueous solution polymerization of acrylic acids, and mercaptoethanol is particularly preferable. The polymerization time varies depending on the polymerization temperature and other conditions and cannot be determined unconditionally, but is usually about 30 minutes to 10 hours.

After the completion of the polymerization reaction, the produced polymer is used as it is or after being converted into a partial or complete alkali metal salt or ammonium salt using an alkali metal hydroxide or ammonia and then isolated by a conventional method. Although the desired acrylic polymer can be obtained, it can be used for a biodegradable builder without isolation, in a state in which the compound used for the polymerization or its decomposition product is mixed. As the polymerization method of (2), in the aqueous medium, the general formula (II)

[0033]

Embedded image

[In the formula, X is a hydrogen atom or an alkali metal atom.
Or an ammonium group, R¹, R ^TwoAnd R^ThreeIs hydrogen
Indicates an atom or a methyl group. ] Acrylic items represented by
Treated with hydrogen peroxide or hydrogen peroxide and a strong acid, and then
Then, this treated product is treated with the same acrylic monomer or
Is mixed with another type of acrylic monomer represented by the general formula (II).
In the method for producing an acrylic polymer,
is there. By treating in this way, effective percarboxylic acid
Can be generated.

This polymerization reaction is a method of conducting aqueous solution polymerization at a temperature of usually 30 to 120 ° C., preferably 70 to 100 ° C. for about 30 minutes to 10 hours. In this method, the treatment of the acrylic monomer with hydrogen peroxide or hydrogen peroxide and a strong acid in an aqueous medium is performed at 25 to 50 ° C.
It is carried out at a temperature of about 10 minutes to 3 hours. The pH at this time is 7 or less, preferably 5 or less.
If the pH exceeds 7, the desired acrylic polymer cannot be obtained.

In this method, hydrogen peroxide is usually used as the hydrogen peroxide, but a water-soluble inorganic peroxide which produces hydrogen peroxide in the reaction system can also be used. The strong acid and the organic sulfonic acid are as described above. Further, in this polymerization reaction, aqueous solution polymerization may be carried out in the presence of a water-soluble reducing agent or a chain transfer agent, if desired, as in the case of the above reaction. Further, after the completion of the polymerization reaction, the resulting polymer, as it is, or after leading to a partial or complete alkali metal salt or ammonium salt using a hydroxide or ammonia of an alkali metal, by isolation according to a conventional method, Although the desired acrylic polymer can be obtained, it can be used for a biodegradable builder in a state where the compound used for the polymerization or its decomposition product is mixed without isolation.

The polymerization method of (3) is carried out in the presence of hydrogen peroxide or hydrogen peroxide and a strong acid in the general formula (II)

[0038]

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[In the formula, X is a hydrogen atom or an alkali metal atom.
Or an ammonium group, R¹, R ^TwoAnd R^ThreeIs hydrogen
Indicates an atom or a methyl group. ] Acrylic items represented by
Mar and the general formula (III)

[0040]

Embedded image

[In the formula, R ⁴ is a hydrogen atom, a methyl group, or -O.
H or -CH ₂ COOX, Y and Z are each a hydrogen atom, a chlorine atom, -COOX, -SO ₃ H, -OH, -O
COR ', - COR', - CONH 2 , or -CHO (X
Is a hydrogen atom, an alkali metal atom or an ammonium group,
R'represents an alkyl group having 1 to 12 carbon atoms. However, acrylic acid, methacrylic acid and crotonic acid are not included. ]
Is a method for producing an acrylic polymer in which the polymerizable unsaturated compound represented by is polymerized in an aqueous solution while keeping the pH of the polymerization system at 7 or less, preferably 5 or less.

Examples of the polymerizable unsaturated compound represented by the general formula (III) include maleic acid, itaconic acid, fumaric acid, α-hydroxyacrylic acid, vinyl sulfonic acid,
Allylsulfonic acid, vinyltoluenesulfonic acid and their alkali metal salts (sodium salt, etc.), ammonium salt, esters of alcohols having 1 to 12 carbon atoms (including esters of allyl alcohol, methallyl alcohol, etc.), acrylamide, Examples include acrolein. These may be used alone or in combination of two or more. Of these, maleic acid is preferred.

This polymerization method may be carried out at the same polymerization temperature and time as in (1) above. Further, it is preferable that hydrogen peroxide and a strong acid coexist. After the completion of the polymerization reaction, the same treatment as in (1) above may be performed. As the polymerization method of (4), in the aqueous medium, the general formula (II)

[0044]

Embedded image

[In the formula, X is a hydrogen atom or an alkali metal atom.
Or an ammonium group, R¹, R ^TwoAnd R^ThreeIs hydrogen
Indicates an atom or a methyl group. ] Acrylic items represented by
Treated with hydrogen peroxide or hydrogen peroxide and a strong acid, and then
Then, this treated product is treated with the same acrylic monomer or
Is the same as another acrylic monomer represented by the general formula (II).
General formula (III)

[0046]

[Chemical 21]

[In the formula, R ⁴ is a hydrogen atom, a methyl group, or -O
H or -CH ₂ COOX, Y and Z are each a hydrogen atom, a chlorine atom, -COOX, -SO ₃ H, -OH, -O
COR ', - COR', - CONH 2 , or -CHO (X
Is a hydrogen atom, an alkali metal atom or an ammonium group,
R'represents an alkyl group having 1 to 12 carbon atoms. However, acrylic acid, methacrylic acid and crotonic acid are not included. ]
Is mixed with another type of acrylic monomer represented by
The following is a method for producing an acrylic polymer, which is preferably aqueous solution polymerization at a pH of 5 or less. General formula (III) is as described above.

This polymerization method may be carried out at the same polymerization temperature and time as in (2) above. After the completion of the polymerization reaction, the same treatment as in (2) above may be performed. The number average molecular weight is 300 to 100,000 by the simple and efficient production method as described above.
The acrylic polymer in the range of can be easily produced. The molecular weight of the acrylic polymer can also be controlled by the reaction conditions such as the concentration and amount of hydrogen peroxide, the concentration and type of acrylic monomer, and the number average molecular weight in which biodegradability and chelating ability are balanced. 1000-25,
Acrylic polymers in the range of 000 can also be easily produced.

Further, the acrylic polymer produced by the method of the present invention using a percarboxylic acid as an initiator does not have only a linear molecular structure like conventional polyacrylic acid, but has a low molecular weight acrylic. It is considered that the acrylic polymers having the above-mentioned number average molecular weight are formed by connecting the branched polymers with each other. This is considered to show biodegradability that polyacrylic acid does not have.

[0050]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The number average molecular weight, molecular structure, Ca ion chelating ability and biodegradation rate of the polymer were determined by the following methods.

(1) Number average molecular weight Polyacrylic acid was measured by gel permeation chromatography (GPC) as a standard substance. As the measurement conditions, ALC / GPC 1 manufactured by Waters, Inc.
50C device (detector: built-in differential refractometer, column: ASA)
Using HIPAK (GSM-700 + GS310),
The mobile phase was acetonitrile / 50 mM sodium acetate = 3.
/ 7, column temperature 40 ° C., flow rate 0.7 ml / mi
n, the injection volume was 200 μl.

(2) Number average molecular weight after hydrolysis 3 g of the sample was dissolved in 25 ml of water, sodium hydroxide was added to adjust the pH to 11, and the mixture was heated and stirred at 80 ° C. for 1 hour for hydrolysis. After completion of the reaction, the pH was adjusted to 7 to 8 and the number average molecular weight of the sample obtained by freeze-drying was measured in the same manner as in (1) above.

(3) Molecular structure by ¹ H-NMR A solution having a polymer concentration of less than 5% with a solvent of deuterated chloroform was used with a GSX-400 apparatus manufactured by JEOL Ltd. to have a diameter of 5 mm.
The test piece was put into a φ test tube, and the operation was performed 32 times at room temperature, 400 MHz, and SGNON mode.

(4) Ca ion chelating ability Aqueous solution 5 containing 10 mg of polymer in a 50 ml beaker and further containing 0.001 mol / liter of calcium chloride and 0.08 mol / liter of potassium chloride.
0 ml was added and mixed in a thermostat at 25 ° C., and the concentration of divalent Ca ions in the aqueous solution was measured by an ion meter. Ca ion chelating ability is 100 g of polymer
Ca ion amount chelated by (g / 100
Expressed as g).

(5) Biodegradation rate The biochemical oxygen demand (BOD) is JIS K01.
According to No. 02-1989, it was determined from the amount of dissolved oxygen consumed when the mixture was stirred at 25 ° C. for 30 days, and the biodegradation rate was calculated according to the following formula. Biodegradation rate (%) = (BOD / TOD) × 100 BOD: biochemical oxygen demand of sample TOD: theoretical oxygen demand of sample

Example 1 In a separable flask having a capacity of 500 ml equipped with a stirrer, a reflux condenser, a thermometer, a pH meter and a chemical pump, 50 ml of water and 24 m of L-ascorbic acid were placed.
g, and kept at a temperature of 98 to 100 ° C. to this,
100 ml of an aqueous solution containing 60 g of acrylic acid, 3
Aqueous solution containing 60 ml of 0 wt% hydrogen peroxide solution 8
A mixed solution of 0 ml and 2 g of mercaptoethanol as a chain transfer agent and 30 ml of water was added dropwise by a chemical pump over 3 hours. During this period, the pH of the polymerization solution was 2.9. After the dropping was completed, the same temperature was maintained for 1 hour to complete the polymerization. The polymer obtained was isolated by freeze-drying.

¹ H-NM of a solution of the obtained polymer obtained by methyl esterification in a heavy chloroform solvent
R is as shown in FIG. 1, and the peak of methylene in contact with the ester was confirmed at 4.1 to 4.6 ppm. In addition,
¹ H-NMR of a conventionally known acrylic acid-based polymer having no branched structure is as shown in FIG. The number average molecular weight of the obtained polymer and the one obtained by hydrolyzing the polymer as described above were measured by GPC. Since the molecular weight after hydrolysis is about 1/4 of that before hydrolysis,
It can be presumed that the acrylic polymer corresponding to the molecular weight after hydrolysis is bonded through an ester bond to give an acrylic polymer having the molecular weight before decomposition. Table 1 shows the properties of this polymer and the builder containing it as a main component.

Example 2 In Example 1, an aqueous solution 10 containing 60 g of acrylic acid was used.
The procedure of Example 1 was repeated, except that 100 ml of an aqueous solution containing 40 g of acrylic acid and 32 g of maleic acid was used instead of 0 ml. However, the pH of the polymerization liquid was 2.5 to 3.0. Table 1 shows the properties of the obtained polymer and the builder containing it as a main component.

Example 3 In the same apparatus as in Example 1, 50 ml of water was added, and
The temperature was kept at 8-100 ° C. To this, acrylic acid 2
A solution obtained by stirring 0 g, 60 ml of 30% by weight hydrogen peroxide and 500 mg of concentrated sulfuric acid at room temperature for 2 hours, and 100 ml of an aqueous solution containing 40 g of acrylic acid were fed by separate chemical pumps over 3 hours. afterwards,
Further, the mixture was heated and stirred at the same temperature for 1 hour. During this period, the pH of the polymerization liquid was 3.1. Table 1 shows the properties of this polymer and the builder containing it as a main component.

Example 4 The same apparatus as in Example 1 was charged with 50 ml of water, and
The temperature was kept at 8-100 ° C. To this, acrylic acid 2
A solution obtained by stirring 0 g, 60 ml of 30% by weight hydrogen peroxide and 500 mg of concentrated sulfuric acid at room temperature for 2 hours, and an aqueous solution containing 20 g of acrylic acid and 32 g of maleic acid.
Milliliters were fed with separate chemical pumps over 3 hours. Then, the mixture was further heated and stirred at the same temperature for 1 hour. During this period, the pH of the polymerization liquid was 2.5 to 3.0.
Table 1 shows the properties of this polymer and the builder containing it as a main component.

Example 5 20 ml of water was placed in a separable flask having a capacity of 500 ml equipped with a stirrer, a reflux condenser, a thermometer, a pH meter and a metering pump, and the temperature was kept at 98 to 100 ° C. An aqueous solution 190 containing 80 g of acrylic acid
Milliliter, 60 ml of 30% by weight hydrogen peroxide and 4 g of mercaptoethanol as chain transfer agent
And a mixed solution of 20 ml of water were supplied by separate metering pumps over 3 hours. During this period, the pH of the polymerization liquid was 3.
It was 0. After the supply was completed, the mixture was further heated and stirred at the same temperature for 1 hour. The polymer obtained was isolated by freeze-drying.
Table 1 shows the properties of this polymer and the builder containing it as a main component.

Example 6 150 ml of water was put in the same apparatus as in Example 1,
The temperature was maintained at 75 ° C to 80 ° C. Acrylic acid 2
A solution prepared by stirring 0 g, 60 ml of 30% by weight hydrogen peroxide and 500 mg of concentrated sulfuric acid at 50 ° C. for 5 hours was supplied by a chemical pump over 3 hours. Then, the mixture was further heated and stirred at the same temperature for 1 hour. During this period, the pH of the polymerization solution was 1.5 to 3.0. The polymer obtained was isolated by freeze-drying. Table 1 shows the properties of this polymer and the builder containing it as a main component.

Comparative Example 1 The pH of the aqueous acrylic acid solution added dropwise in Example 1
Was carried out in the same manner as in Example 1 except that sodium hydroxide was adjusted to 7.5. The pH of the polymerization liquid during the dropwise addition was 7.1 to 7.8. Table 1 shows the properties of the obtained polymer and the builder containing it as a main component.

Comparative Example 2 The pH of the acrylic acid aqueous solution added dropwise in Example 5
Was carried out in the same manner as in Example 6 except that the concentration was adjusted to 8.1 with sodium hydroxide. The pH of the polymerization liquid during dropping was 7.5 to 8.6. Table 1 shows the properties of the obtained polymer and the builder containing it as a main component.

[0065]

[Table 1]

[0066]

The present invention can provide a method for efficiently producing an acrylic polymer having excellent chelating ability and biodegradability.

[Brief description of drawings]

1 shows the structural units (I) and (I obtained in Example 1).
¹ H-NMR absorption spectrum of acrylic polymer consisting of I)

FIG. 2 ¹ H-NMR absorption spectrum of an ordinary unbranched acrylic polymer consisting of structural unit (I) only.

Claims (6)

[Claims] 1. A compound represented by the general formula (I): [In the formula, R ¹ , R ² and R ³ represent a hydrogen atom or a methyl group. ] With a percarboxylic acid represented by the polymerization initiator,
A method for producing an acrylic polymer, which comprises polymerizing an acrylic monomer at a pH of 7 or less. 2. The presence of hydrogen peroxide or hydrogen peroxide and a strong acid.
Below, general formula (II)[In the formula, X is a hydrogen atom, an alkali metal atom, or an ammonia.
R represents an um group¹, R ^TwoAnd R^ThreeIs a hydrogen atom or methyl
Represents a hydroxyl group. ] The acrylic monomer represented by
Water-soluble polymerization while maintaining the pH of the system below 7
A method for producing a characteristic acrylic polymer. 3. A compound represented by the general formula (II):[In the formula, X is a hydrogen atom, an alkali metal atom, or an ammonia.
R represents an um group¹, R ^TwoAnd R^ThreeIs a hydrogen atom or methyl
Represents a hydroxyl group. ] The acrylic monomer represented by
Treat with hydrogen peroxide or hydrogen peroxide and strong acid, then this treatment
The same type of acrylic monomer or the general formula (II)
Is mixed with another type of acrylic monomer represented by
An acrylic-based polymer characterized by being polymerized in an aqueous solution below.
Manufacturing method of coalescence. 4. The presence of hydrogen peroxide or hydrogen peroxide and a strong acid.
Below, the general formula (II)[In the formula, X is a hydrogen atom, an alkali metal atom, or an ammonia.
R represents an um group¹, R ^TwoAnd R^ThreeIs a hydrogen atom or methyl
Represents a hydroxyl group. ] An acrylic monomer represented by
Formula (III)[Wherein, R^FourIs a hydrogen atom, a methyl group, -OH or -CH
_TwoCOOX, Y and Z are hydrogen atom and chlorine atom, respectively.
Child, -COOX, -SO_ThreeH, -OH, -OCOR ',
-COR ', -CONH_TwoOr -CHO (X is hydrogen source)
Child, alkali metal atom or ammonium group, R'is carbon
The alkyl groups of the numbers 1 to 12 are shown. However, acrylic acid,
Does not contain methacrylic acid and crotonic acid. ]
Do not keep the pH of the polymerization system below 7 for polymerizable unsaturated compounds.
Acrylic polymerization characterized by the aqueous solution polymerization
How to make the body. 5. In the aqueous medium, the compound represented by the general formula (II):[In the formula, X is a hydrogen atom, an alkali metal atom, or an ammonia.
R represents an um group¹, R ^TwoAnd R^ThreeIs a hydrogen atom or methyl
Represents a hydroxyl group. ] The acrylic monomer represented by
Treat with hydrogen peroxide or hydrogen peroxide and strong acid, then this treatment
The same type of acrylic monomer or the general formula (II)
Another type of acrylic monomer represented by the general formula (III)[Wherein, R^FourIs a hydrogen atom, a methyl group, -OH or -CH
_TwoCOOX, Y and Z are hydrogen atom and chlorine atom, respectively.
Child, -COOX, -SO_ThreeH, -OH, -OCOR ',
-COR ', -CONH_TwoOr -CHO (X is hydrogen source)
Child, alkali metal atom or ammonium group, R'is carbon
The alkyl groups of the numbers 1 to 12 are shown. However, acrylic acid,
Does not contain methacrylic acid and crotonic acid. ]
Polymerizable unsaturated compound is mixed and aqueous solution polymerization at pH 7 or below
A method for producing an acrylic polymer, which comprises: 6. The number average molecular weight of the acrylic polymer is 300.
The method for producing an acrylic polymer according to claim 1, which is in the range of 100,000 to 100,000.