JP2000212217A - Production of aromatic-compound-substituted carboxylic acid polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently obtain an aromatic-compound-substituted carboxylic acid polymer having a high chelating capacity and excellent biodegradability by reacting a copolymer of maleic anhydride with (meth)acrylic acid with an aromatic compound. SOLUTION: A copolymer comprising repeating units of formula I and repeating units of formula II is reacted with an aromatic compound of formula III. In formula II, R1 is H or methyl; X is H, an alkali metal, or ammonium. In formula III, Ar is a group having 1-3 aromatic rings; R2 and R3 are each H or a 1-10C alkyl; R4 is 1-10C alkyl, hydroxyl, or amino; and (m) is 0-4. The copolymer desirably is the one having a ratio, maleic acid units/(meth)acrylic acid units, of 50/50 to 0.5/99.5 by mole. In the reaction with the copolymer, it is desirable that the amount of the aromatic compound is such that the content of structural units comprising residues of the aromatic compound in the aromatic- compound-substituted carboxylic acid polymer obtained by the reaction is 0.5-20 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an aromatic compound-substituted carboxylic acid polymer. For more information,
The present invention relates to an effective method for producing an aromatic compound-substituted carboxylic acid polymer having excellent biodegradability and excellent performance as a detergent builder.

[0002]

2. Description of the Related Art Conventionally, in detergents containing a surfactant as a main component used for washing textiles and the like, the washing ability has been increased by blending a builder as an auxiliary component of the surfactant. I have. As this builder, an inorganic compound showing alkalinity when added to water,
Polymers of unsaturated carboxylic acids and the like are known. Examples of the former include sodium or potassium carbonates, bicarbonates, phosphates, polyphosphates, silicates and zeolites, and examples of the latter include polyacrylic acid, polymaleic acid, polyitaconic acid, etc. There is.

Among these builders, sodium tripolyphosphate, which has excellent builder performance and does not form an insoluble precipitate even when hard water is used, has been frequently used. However, since sodium tripolyphosphate causes eutrophication in lakes and rivers, there is a problem in terms of environmental protection. Therefore, zeolite has been used as an alternative, but since zeolite alone does not have sufficient performance, the performance as a builder is supplemented by using a high molecular weight polycarboxylic acid in combination. However, this zeolite has a problem of sedimentation, and since high molecular weight polycarboxylic acid does not have biodegradability, it remains for a long period of time and has environmental problems.

Therefore, it has at least the performance as a builder similar to the conventional product, in particular, the chelating ability (calcium ion capturing ability), and is highly important in terms of environmental protection. There is a demand for the development of a so-called environmentally friendly and economically advantageous builder that does not remain for a long period. In response to such a request, JP-A-5-239127 discloses a polymer suitable for use as a builder having chelating ability and biodegradability, although the polymer itself has almost no chelating ability, By linking the main chains of the water-soluble oligomers containing low molecular weight components having biodegradability with a cross-linking agent such as polyethylene glycol, citric acid and tartaric acid via a biodegradable ester group or amide group, Cross-linked polymers with increased molecular weight have been proposed.
However, this crosslinked polymer has improved biodegradability by reducing the molecular weight, but linear polyacrylic acid itself is difficult to biodegrade, and high-molecular-weight linear polyacrylic, which is difficult to biodegrade. The biodegradability is not sufficiently high because it contains a considerable amount of acid. Further, in the production process of this crosslinked polymer, it is necessary to perform in two stages of a process of polymerizing the oligomer and a process of crosslinking, and it is necessary to use a specific crosslinking agent, so that the production process is complicated. Has disadvantages.

In Japanese Patent Application Laid-Open No. 50-80377, it is proposed to use a copolymer obtained by copolymerizing acrylic acid with acrolein as a builder. Neither of them is sufficient, and they are not satisfactory in terms of economy, so they have not been put to practical use.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for efficiently producing an aromatic compound-substituted carboxylic acid polymer having excellent chelating ability and high biodegradability. is there.

[0007]

Means for Solving the Problems The present inventors have made intensive studies to achieve the above object, and as a result, have found that a copolymer having a residue of maleic anhydride has an aromatic compound having a specific chemical structure. By introducing a compound, they have found that an aromatic compound-substituted carboxylic acid polymer having excellent chelating ability and high biodegradability can be efficiently produced, and the present invention has been completed based on such findings. .

That is, the gist of the present invention is as follows. (1) The following formula [1],

[0009]

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And a repeating unit represented by the following general formula [2]:

[0011]

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In the copolymer having a repeating unit represented by the formula (2), R ¹ represents a hydrogen atom or a methyl group, and X represents a hydrogen atom, an alkali metal atom or an ammonium group. The following general formula [3]

[0013]

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[0014] [Ar in the formula (3) indicates a 1-3 aromatic rings, R ^2, R ³ each independently represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, R ⁴ Is carbon number 1 to 1
0 represents an alkyl group, a hydroxyl group or an amino group;
A method of producing an aromatic compound-substituted carboxylic acid polymer. (2) When reacting a copolymer of maleic anhydride and acrylic acid or methacrylic acid with an aromatic compound represented by the above general formula [3], the aromatic compound in the aromatic compound-substituted carboxylic acid polymer (1) The method for producing an aromatic compound-substituted carboxylic acid polymer according to the above (1), wherein the content ratio of the structural unit consisting of the residue is 0.5 to 20% by weight.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing an aromatic compound-substituted carboxylic acid polymer according to the present invention comprises a structural unit comprising a residue of maleic anhydride represented by the above formula [1] and a compound represented by the above general formula [2]
Is reacted with a copolymer having a structural unit consisting of a residue of acrylic acid or methacrylic acid represented by the general formula [3] to give an aromatic compound-substituted carboxylic acid. This is a method for producing an acid polymer.

In the method of the present invention, the molar ratio of the structural unit consisting of maleic anhydride residues and the structural unit consisting of acrylic acid or methacrylic acid residues used in the reaction is 50:50. ~ 0.5: 99.5,
A copolymer having a copolymer composition of preferably 50:50 to 10:90 is suitably used. That is, when the molar ratio of the structural unit composed of maleic anhydride residues in the copolymer exceeds 0.5, the reactivity of the aromatic compound represented by the above formula [3] with the copolymer is increased. , And the biodegradability of the resulting aromatic compound-substituted carboxylic acid polymer may be reduced.

The number average molecular weight of the copolymer of maleic anhydride and acrylic acid or methacrylic acid is as follows:
It is preferable to use those having a number average molecular weight of less than 1,000 when the number average molecular weight is less than 1,000. The trapping ability may be reduced, and the number average molecular weight is 1,000,000
When the amount exceeds 00, the biodegradability of the obtained aromatic compound-substituted carboxylic acid polymer may decrease.

In order to prepare a copolymer of maleic anhydride and acrylic acid or methacrylic acid, a predetermined ratio of maleic anhydride and acrylic acid or methacrylic acid is added to a copolymer in the presence of an aprotic solvent. What is necessary is just to make it react at -130 degreeC. Next, the thus obtained copolymer of maleic anhydride and acrylic acid or methacrylic acid is reacted with an aromatic compound represented by the above general formula [3] to obtain an aromatic compound-substituted carboxylic acid. Produce an acid polymer.

The aromatic compound represented by the general formula [3] includes 1 to 3 represented by Ar in the general formula [3].
And the aromatic ring is a benzene ring, a naphthalene ring or an anthraquinone ring, wherein the alkyl group having 1 to 10 carbon atoms represented by R ^{2 to} R ⁴ is a methyl group, an ethyl group, an n-propyl group, or an isopropyl group. , N-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, etc. There are some. Of these, a methyl group,
An ethyl group, an n-propyl group and an n-butyl group.

Specific examples of the aromatic compound represented by the general formula [3] include, for example, hydroquinone, 2-methylhydroquinone, 2,5-dimethylhydroquinone, 2,5-dimethoxyhydroquinone,
Hydroxymethyl-hydroquinone, resorcinol,
4-methylresorcinol, 5-aminoresorcinol, catechol, pyrogallol, p-methoxyphenol, 2-amino-4-methoxyphenol, 1,5-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxyanthraquinone, 2,5-dimethoxy Examples include aniline, 2,5-dihydroxyaniline, and 2,5-dihydroxy-4-methylaniline.

The reaction ratio of the aromatic compound represented by the general formula [3] to the copolymer of maleic anhydride and acrylic acid or methacrylic acid is as follows. The aromatic compound-substituted carboxylic acid polymer obtained by the reaction has a content ratio of the structural unit consisting of the residue of the aromatic compound of 0.5 to 20% by weight, preferably 1 to 10% by weight. It is desirable to do. In this case, when the content of the structural unit is less than 0.5% by weight, the biodegradability required when the aromatic compound-substituted carboxylic acid polymer obtained by this reaction is used as a builder may be satisfied. There are things you can't do. On the other hand, when the content of the structural unit exceeds 20% by weight, the ability of the resulting aromatic compound-substituted carboxylic acid polymer to capture calcium ions may decrease. Therefore, it is desirable to set the content ratio within the above range.

The copolymer of maleic anhydride and acrylic acid or methacrylic acid used in the reaction of the present invention has structural units represented by the above formulas (1) and (2). Further, as the third structural unit, a unit having a chemical structure containing a structural unit derived from an unsaturated compound different from maleic anhydride, acrylic acid, or methacrylic acid may be used. Unsaturated compounds suitable for producing a copolymer containing this third structural unit include fumaric acid, acrolein, vinyl acetate, methyl acrylate, ethyl acrylate, and the like. And
When such a structural unit is contained, a three-component copolymer may be produced in advance using monomers for forming the above three types of structural units as raw materials. Further, it is desirable that the usage ratio of these unsaturated compounds be less than 30% by weight in the content ratio in the obtained aromatic compound-substituted carboxylic acid polymer. When reacting these unsaturated compounds with the copolymer, the content of the aromatic compound-substituted carboxylic acid polymer having a tendency to decrease the water solubility is preferably reduced.

Next, the reaction conditions for producing the aromatic compound-substituted carboxylic acid polymer are represented by the general formula [3] and the copolymer of maleic anhydride and acrylic acid or methacrylic acid. The aromatic compound may be reacted under acidic conditions at a temperature of 20 to 130 ° C. for 10 minutes to 10 hours. As a catalyst for performing this reaction, for example, sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, p-toluenesulfonic acid and the like are suitable. As the reaction solvent, acetic acid, 1,4-dioxane, tetrahydrofuran, dimethyl sulfoxide and the like are suitably used.

The number average molecular weight of the aromatic compound-substituted carboxylic acid polymer thus obtained is from 1,000 to 1,
1,000,000, preferably 1,000-10
000 range, more preferably 1,000 to 5
It is in the range of 0000. This number average molecular weight is 1,000
If it is less than 0, when it is used as a builder, sufficient chelating ability cannot be obtained, while it may not be 1,000,000.
If it exceeds 000, the biodegradability is reduced, so that the above range is preferable.

The biodegradable builder of the present invention comprising the aromatic compound-substituted carboxylic acid polymer thus obtained has excellent chelating ability and high biodegradability, and is suitably used as a detergent builder. be able to.
In addition, by using the aromatic compound-substituted carboxylic acid polymer in combination with a surfactant, a detergent composition having biodegradability can be obtained. As such a surfactant, for example, an anionic surfactant, a cationic surfactant, a nonionic surfactant, an amphoteric surfactant and the like can be used.

In the detergent composition, the builder and the surfactant are preferably blended in an amount of 1 to 40% by weight, and the surfactant is preferably 10 to 40% by weight based on the total amount of the detergent composition. The balance of 20 to 89% by weight is preferably prepared by appropriately blending an enzyme, a bleaching agent, an inorganic builder (eg, zeolite, sodium carbonate) and the like.

Examples of the above-mentioned anionic surfactant include fatty acid soap, alkyl ether carboxylate, N
-Acyl amino acid salts, alkyl benzene sulfonates,
Alkyl naphthalene sulfonate, dialkyl sulfosuccinate, α-olefin sulfonate, higher alcohol sulfate, alkyl ether sulfate,
Polyoxyethylene alkyl phenyl ether sulfate,
Sulfate, alkyl ether phosphate, alkyl phosphate, and the like of fatty acid alkylolamide are preferably used.

As the cationic surfactant, aliphatic amine salts, aliphatic quaternary ammonium salts, benzalkonium salts, benzethonium chloride, pyridinium salts, and imidazolinium salts are preferred. Further, as nonionic surfactants, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether,
Polyoxyethylene polyoxypropylene block polymer, polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene glycerin fatty acid ester, polyoxyethylene castor oil, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, polyethylene glycol fatty acid ester, Preferred are fatty acid monoglyceride, polyglycerin fatty acid ester, sorbitan fatty acid ester, fatty acid alkanolamide, polyoxyethylene fatty acid amide, polyoxyethylene alkylamine, alkylamine oxide and the like.

As the amphoteric surfactant, for example, a carboxybetaine type compound, an aminocarboxylate, imidazolinium betaine and the like are suitable. Further, the aromatic compound-substituted carboxylic acid polymer obtained in the present invention is neutralized with an aqueous solution of an alkali, for example, sodium hydroxide or potassium hydroxide, by a conventional method to obtain a hydrophilic aromatic compound-substituted carboxylic acid. A polymer is obtained. The thus obtained aromatic compound-substituted carboxylic acid polymer imparted with hydrophilicity can be used as a dispersant. The dispersant comprising the aromatic compound-substituted carboxylic acid polymer imparted with hydrophilicity is suitable for dispersing in water for inorganic pigments such as calcium carbonate and clay used in coating agents such as paper. In preparing such a coating agent, the dispersant is added at a ratio of 0.05 to 2.0 parts by weight with respect to 100 parts by weight of an inorganic pigment such as calcium carbonate or clay, and is added to water. What is necessary is just to disperse. By using this dispersant, the coating agent can have a low viscosity and a high fluidity. In this case, the dispersant may be used alone, or another compounding agent such as polyvinyl alcohol may be used in combination.

Further, the aromatic compound-substituted carboxylic acid polymer obtained in the present invention has excellent chelating ability.
It is also highly useful as a scale adhesion inhibitor in cooling water systems, boiler water systems, and the like.

[0031]

[Example 1]

(1) Production of maleic anhydride-acrylic acid copolymer Maleic anhydride 2 was placed in a 500 ml separable flask equipped with a stirrer, a reflux condenser, and a thermocouple.
4.5 g and 250 ml of a solvent, benzene, were charged and heated to 80 ° C.

Then, 0.82 g of azobisisobutylnitrile as a polymerization initiator was added to 18.0 g of acrylic acid.
And added dropwise over 30 minutes with stirring. After the completion of the dropwise addition of the solution, the reaction was further continued under stirring at 80 ° C. for 2 hours. Next, after this reaction was completed, benzene as a solvent was distilled off from the obtained reaction product to obtain 18.50 g of a maleic anhydride-acrylic acid copolymer represented by the following formula.

[0033]

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The number average molecular weight of the obtained copolymer measured by gel permeation chromatography (GPC) using polyacrylic acid as a standard substance was 6,700. The weight average molecular weight of this polymer was 86,000. (2) Production of aromatic compound-substituted carboxylic acid polymer The maleic anhydride-acrylic acid copolymer obtained in the above (1) was placed in a separable flask having a capacity of 100 ml and equipped with a stirrer, a reflux condenser, and a thermocouple. 2.5g
And an aromatic compound represented by the general formula [3]:
0.1 g of hydroquinone, 5 ml of acetic acid as a solvent, and 0.05 g of sulfuric acid as a catalyst were added, heated to 110 ° C., and reacted with stirring for 2 hours.

Then, after the completion of the reaction, 50 parts of water was added to the reaction product.
The solution was adjusted to pH 10 by adding milliliter and sodium hydroxide. Next, this was freeze-dried to obtain 3.37 g of a target aromatic compound-substituted carboxylic acid polymer. The obtained aromatic compound-substituted carboxylic acid polymer had a number average molecular weight of 9,200 and a weight average molecular weight of 132,000.

From the results of ¹ H-NMR measurement of this polymer, the absorption based on the main chain of the polymer was found at 1.2 to 3.0 ppm, and the absorption derived from the benzene ring was found at 7.0 to 7.4 ppm. From these results and the raw material charge ratio, it was confirmed that the chemical structure of this polymer was as follows.

[0037]

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(3) Evaluation of calcium ion scavenging ability 20 mg of the aromatic compound-substituted carboxylic acid polymer obtained in the above (2) was put into a 200 ml beaker, and then 0.1N of calcium chloride was added thereto. 100 g of an aqueous solution having a calcium ion concentration of 40 ppm, containing 0.1 N of potassium chloride and 0.4 N of ammonia, were dissolved therein. Next, the concentration of divalent calcium ions in the aqueous solution was measured using a calcium ion electrode, converted to calcium carbonate (unit: mg) captured by 1 g of the polymer, and this value was calculated as the calcium ion capturing ability. And As a result of this measurement, the ability of the aromatic compound-substituted carboxylic acid polymer obtained in the above (2) to capture calcium ions was 180 mg / g.

(4) Evaluation of biodegradability The biodegradability of the aromatic compound-substituted carboxylic acid polymer obtained in the above (2) was measured according to JIS K6950. The biodegradation rate was calculated from TOC (total organic carbon content). As a result of this measurement, the biodegradability of the aromatic compound-substituted carboxylic acid polymer obtained in the above (2) was 70%. Table 1 summarizes these results.

Example 2 (1) Production of maleic anhydride-acrylic acid copolymer A maleic anhydride-acrylic acid copolymer was produced by the same operation as in Example 1, (1). (2) Production of aromatic compound-substituted carboxylic acid polymer The maleic anhydride-acrylic acid copolymer obtained in the above (1) was placed in a separable flask having a capacity of 100 ml and equipped with a stirrer, a reflux condenser, and a thermocouple. And 2.5-g of an aromatic compound represented by the general formula [3].
0.1 g of dimethoxyaniline and 10 ml of 1,4-dioxane as a solvent were added and reacted at 25 ° C. for 3 hours with stirring.

Then, after the completion of the reaction, 50 parts of water was added to the reaction product.
The solution was adjusted to pH 10 by adding milliliter and sodium hydroxide. Next, this was freeze-dried to obtain 3.35 g of a target aromatic compound-substituted carboxylic acid polymer. The number average molecular weight of the obtained aromatic compound-substituted carboxylic acid polymer was 11,000, and the weight average molecular weight thereof was 154,000.

From the measurement results of this polymer by ¹ H-NMR, the absorption based on the main chain of the polymer was found to be 1.2 to 3.0 ppm, and the absorption derived from the benzene ring was found to be 7.0 to 7.9 ppm. From these results and the raw material charge ratio, it was confirmed that the chemical structure of this polymer was as follows.

[0043]

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(3) Evaluation of Calcium Ion Capturing Ability The calcium ion capturing ability of the aromatic compound-substituted carboxylic acid polymer obtained in the above (2) was measured in the same manner as in Example 1 (3). It was 190 mg / g.

(4) Evaluation of biodegradability The biodegradability of the aromatic compound-substituted carboxylic acid polymer obtained in (2) was measured in the same manner as in (1) of Example 1, and as a result, it was 65%. there were. The results are shown in Table 1.

[0046]

[Table 1]

Example 3 (1) Preparation of Detergent Composition After the aromatic-substituted carboxylic acid polymer obtained in (2) of Example 1 was converted to an aqueous solution, its liquid property was adjusted to pH 10
Was adjusted. Next, the aromatic compound-substituted carboxylic acid polymer obtained here was used as a builder, and 20 parts by weight of this builder was used as a surfactant as sodium linear alkylbenzene sulfonate [abbreviated as LAS in Table 2]. ] 25 parts by weight, 10 parts by weight of sodium alkyl sulfate (abbreviated as AS in Table 2), 10 parts by weight of sodium silicate as other additives, and 2 parts by weight of polyethylene glycol [abbreviated as PEG in Table 2] , 20 parts by weight of sodium carbonate and 13 parts by weight of water to prepare a detergent composition. (2) Evaluation of Detergency of Detergent Composition Next, an evaluation test of the detergency of the detergent composition obtained in the above (1) was performed. As the artificial soil used here, one having the following composition was prepared.

Organic Soil Component 69.7 parts by weight Baking Viscosity 29.8 parts by weight Carbon Black 0.5 part by weight As the organic soil component, those containing the following substances at predetermined ratios are used. Using.

Oleic acid 28.3 parts by weight Triolein 15.6 parts by weight Cholesterol olein 12.2 parts by weight Liquid paraffin 2.5 parts by weight Squalene 2.5 parts by weight Cholesterol 1.6 parts by weight Gelatin 7.0 parts by weight 69.7 parts by weight Next, using this artificial soil, a contaminated cloth is prepared from a clean cloth by a water solvent-based wet method, and cut into 5 cm × 5 cm to obtain a cloth having a reflectance of 38 to 43%. After preparing and measuring the surface reflectance before cleaning, a cleaning test was performed under the following conditions.

Tester Terg-O-Tometer Rotational speed 120 rpm Water hardness 90 ppm (CaCO ₃ equivalent) Wash amount 900 ml Wash temperature 30 ° C. Detergent concentration 0.067% Bath ratio 30 times Wash time 10 minutes Rinse time 3 minutes Dry twice Iron on the filter paper, then measure the surface reflectance of the washed cloth (wash cloth)
The detergency was determined from the following equation.

Detergency (%) = [(K / S of dirty cloth−K / S of cleaning cloth) / (K / S of dirty cloth−K / S of cleaning cloth)]
× 100 [where K / S = (1−R) ² / 2R (Kub
Elka-Munk equation), and R represents the surface reflectance of the cloth. As a result of evaluating the detergency of the detergent composition as described above, the detergency of the detergent composition obtained in the above (1) was 60%.
%Met. Table 2 shows the compositions of these detergent compositions and the results of the evaluation of detergency.

Example 4 (1) Preparation of Detergent Composition Example 3 except that the aromatic-substituted carboxylic acid polymer obtained in (2) of Example 2 was used as a builder.
A detergent composition was prepared in the same manner as (1).

(2) Evaluation of Detergency of Detergent Composition The detergency of the detergent composition was evaluated in the same manner as in (2) of Example 3, except that the detergent composition prepared in (1) was used. . Table 2 shows the compositions of these detergent compositions and the results of the evaluation of detergency.

[0054]

[Table 2]

Example 5 (1) Preparation of Dispersion The aromatic-substituted carboxylic acid polymer obtained in (2) of Example 1 was prepared so that its concentration was 10 ppm.
In addition, a dispersion was prepared by dissolving the activated clay in water so that the concentration thereof was 1% by weight.

(2) Evaluation of dispersion performance After stirring 100 ml of this dispersion for 10 minutes,
It was placed in a 100 ml graduated cylinder and allowed to stand for 14 hours. Next, 5 ml of the supernatant of this dispersion was sampled, the absorbance was measured using a light source having a wavelength of 400 nm, and the value was evaluated as an index of the dispersion performance of the polymer. The absorbance when this polymer was used as a dispersant was 0.125. In the blank test, the absorbance was 0.000. Table 3 shows the evaluation results of the dispersion performance.

Example 6 (1) Preparation of Dispersion A dispersion was prepared in the same manner as (1) of Example 5, except that the aromatic-substituted carboxylic acid polymer obtained in (2) of Example 2 was used. Thus, a dispersion was prepared. (2) Evaluation of Dispersibility The dispersibility was evaluated in the same manner as in (2) of Example 5, except that the dispersion prepared in (1) was used. Table 3 shows the evaluation results of the dispersion performance.

[0058]

[Table 3]

[0059]

According to the production method of the present invention, an aromatic compound-substituted carboxylic acid polymer which is highly useful as a detergent builder, a detergent composition and a dispersant having excellent calcium ion trapping ability and excellent biodegradability. Coalescence can be manufactured efficiently.

Claims (2)

[Claims] 1. A compound represented by the following formula [1]: And a repeating unit represented by the following general formula [2]: [In the formula (2), R ¹ represents a hydrogen atom or a methyl group, and X represents a hydrogen atom, an alkali metal atom or an ammonium group.] A copolymer having a repeating unit represented by the following general formula: [3] [Ar in the formula [3] represents 1 to 3 aromatic rings;
² and R ³ each independently represent a hydrogen atom or a group having 1 to 10 carbon atoms.
R ⁴ represents an alkyl group having 1 to 10 carbon atoms, a hydroxyl group or an amino group, and m represents an integer of 0 to 4]. A method for producing an aromatic compound-substituted carboxylic acid polymer. 2. The reaction of an aromatic compound represented by the general formula [3] with a copolymer of maleic anhydride and acrylic acid or methacrylic acid when the aromatic compound in the aromatic compound-substituted carboxylic acid polymer is reacted. The method for producing an aromatic compound-substituted carboxylic acid polymer according to claim 1, wherein the content ratio of the structural unit comprising the residue of the aromatic compound is adjusted to 0.5 to 20% by weight.