JP2000001508A - Production of copolymer of monoethylenically unsaturated carboxylic acid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a copolymer free from unreacted residual maleic acid either by effecting the copolymerization reaction of a monoethylenically unsaturated carboxylic acid with maleic anhydride in the presence of a sulfur-containing compound or by adding a sulfur-containing compound to the copolymerization reaction mixture and reacting the compound. SOLUTION: A sulfur-containing compound represented by the formula; MnHSaOb (wherein M is an alkali metal, an alkaline earth metal, or ammonium; n is 1 or 1/2; a is 1 or 2; and b is 0 or 3) or the formula: MmSaOb [wherein is 1 or 2; a is 1 or 2; and b is 0, 3 or 5 (a is 1 when b is 0)] is used. Among the sulfur-containing compounds, NaHSO3, Na2SO3, Na2S2O4, Na2SO4, Na2S2O3, and Na2S are desirable. The amount of the sulfur-containing compound added is desirably 0.1-30 wt.% based on the total monomer to be polymerized. The monoethylenically unsaturated carboxylic acid used is desirably acrylic acid or methacrylic acid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a monoethylenically unsaturated carboxylic acid-maleic acid copolymer or monoethylenically unsaturated copolymer suitably used as a biodegradable builder, a biodegradable dispersant and a detergent composition. The present invention relates to a method for producing a carboxylic acid-maleic anhydride copolymer. For more information,
The present invention relates to a method for producing the copolymer containing no residual unreacted maleic acid.

[0002]

2. Description of the Related Art Conventionally, in a detergent containing a surfactant as a main component, a builder is blended as an auxiliary component of the surfactant to improve the washing performance. As the builder, an inorganic compound showing an alkalinity when added to water, a polymer of an unsaturated aliphatic carboxylic acid, and the like are known. Examples of the former include sodium and potassium carbonates, bicarbonates, phosphates, polyphosphates, silicates and zeolites, and examples of the latter include polyacrylic acid, polymaleic acid and polyitaconic acid. And their alkali metal salts.

[0003] Among these builders, phosphates, polyphosphates and zeolites are used in large amounts in view of their effects, economy and workability. However, phosphates and polyphosphates cause eutrophication of lakes and rivers, and zeolite has problems in terms of global environmental protection such as sedimentation in rivers and lakes due to its water insolubility. ing.

Further, polyacrylic acid, polymaleic acid,
Water-soluble organic builders such as polyitaconic acid and their alkali metal salts have a problem that their biodegradability is extremely poor. For this reason, it is at least excellent in performance as a builder (particularly, chelating ability) as in the past, and of course, it has a biodegradability that is important for global environmental protection and does not remain for a long time. There is a need for the development of an easy and economically advantageous builder.

Under these circumstances, acrylic acid and maleic anhydride or maleic acid, which are suitable for use as a biodegradable builder and a biodegradable dispersant, and have no coloring and excellent chelating ability, are copolymerized. A method for producing an acrylic acid polymer has been proposed. Conventionally, when acrylic acid and maleic anhydride or maleic acid are copolymerized, there has been a problem that maleic acid remains as an unreacted substance due to its lower reactivity than acrylic acid. Since maleic acid is a substance that is not preferred in terms of physiological activity, various polymerization techniques have been improved to reduce the amount of unreacted maleic acid in the polymer, but it is still not sufficient. For example, a method of adjusting pH, a method of polymerizing maleic anhydride in an organic solvent, and the like have been conventionally proposed, but all have a problem that the apparatus and operation are complicated. A method of converting maleic acid to fumaric acid using a microorganism has also been proposed, but the apparatus and operation are complicated and impractical.

[0006]

SUMMARY OF THE INVENTION Under such circumstances, the present invention provides a monoethylenically unsaturated carboxylic acid and maleic anhydride which are suitably used as a biodegradable builder, a biodegradable dispersant and a detergent composition. An object of the present invention is to provide a method for producing an acid or maleic acid copolymer, which method does not contain unreacted residual maleic acid.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, by conducting a polymerization reaction in the presence of a specific sulfur-containing compound, unreacted residual maleic acid was obtained. The present inventors have found that an acrylic acid-maleic anhydride copolymer containing no acrylic acid can be obtained, and have completed the present invention based on such findings.

That is, the present invention provides the following. 1. A monoethylenically unsaturated carboxylic acid and maleic anhydride or maleic acid copolymerization reaction in the presence of a sulfur-containing compound represented by the following general formula (1) or (2): A method for producing an unsaturated carboxylic acid copolymer. _{M n H S a O b ···} (1) (M is an alkali metal, alkaline earth metal or ammonium, n represents 1 or 1/2, a is 1 or 2, and b is 0 or 3 _{) M m S a O b ···} (2) (M is an alkali metal, alkaline earth metal or ammonium, m is 1 or 2, a is 1 or 2, and b
Is 0, 3, or 4, and when b is 0, a is 1.) After conducting a copolymerization reaction of monoethylenically unsaturated carboxylic acid and maleic anhydride or maleic acid, a sulfur-containing compound represented by the following general formula (1) or (2) is added and reacted. For producing a monoethylenically unsaturated carboxylic acid copolymer. _{M n H S a O b ···} (1) (M is an alkali metal, alkaline earth metal or ammonium, n represents 1 or 1/2, a is 1 or 2, and b is 0 or 3 _{) M m S a O b ···} (2) (M is an alkali metal, alkaline earth metal or ammonium, m is 1 or 2, a is 1 or 2, and b
Is 0, 3, or 4, and when b is 0, a is 1.) When the sulfur-containing compound is NaHSO ₃ , Na ₂ SO ₃ ,
Na ₂ S ₂ O ₄ , Na ₂ SO ₄ , Na ₂ S ₂ O ₃ or N
_{3. The} method for producing a monoethylenically unsaturated carboxylic acid copolymer according to the above 1 or 2, which is a ₂ S. 4. 4. The method for producing a monoethylenically unsaturated carboxylic acid copolymer according to any one of the above items 1 to 3, wherein the amount of the sulfur-containing compound to be added is 0.1 to 30% by weight based on all monomers subjected to the polymerization. 5. 5. The method for producing a monoethylenically unsaturated carboxylic acid copolymer according to any one of the above items 1 to 4, wherein the monoethylenically unsaturated carboxylic acid is acrylic acid or methacrylic acid.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The first invention of the present invention is to provide a monoethylenically unsaturated carboxylic acid and maleic anhydride or maleic anhydride by the presence of a sulfur-containing compound represented by the following general formula (1) or (2). A method for producing a monoethylenically unsaturated carboxylic acid copolymer containing no unreacted residual maleic acid, comprising performing a maleic acid copolymerization reaction. _{M n H S a O b ···} (1) (M is an alkali metal, alkaline earth metal or ammonium, n represents 1 or 1/2, a is 1 or 2, and b is 0 or 3 _{) M m S a O b ···} (2) (M is an alkali metal, alkaline earth metal or ammonium, m is 1 or 2, a is 1 or 2, and b
Is 0, 3 or 4, and when b is 0, a is 1)
In the second invention of the present invention, after a copolymerization reaction of a monoethylenically unsaturated carboxylic acid and maleic anhydride or maleic acid is carried out, a compound represented by the above general formula (1) or (2) is contained. A method for producing a monoethylenically unsaturated carboxylic acid copolymer containing no unreacted residual maleic acid, characterized by adding a sulfur compound and reacting.

In the present invention, the copolymerization reaction between a monoethylenically unsaturated carboxylic acid and maleic anhydride or maleic acid is carried out in an aqueous solvent, a non-aqueous solvent or without a solvent.
It can be carried out using a polymerization initiator. In the present invention, examples of the monoethylenically unsaturated carboxylic acid include acrylic acid, methacrylic acid, ethacrylic acid, fumaric acid,
Examples thereof include citraconic anhydride, citraconic acid, itaconic anhydride, and itaconic acid, which may be used alone or in combination of two or more. Of these, acrylic acid and methacrylic acid are particularly preferred.

In the present invention, the amount of monomer supplied at the time of production is determined from the viewpoint of the chelating ability and biodegradability of the obtained monoethylenically unsaturated carboxylic acid copolymer and the production from the viewpoint of controlling the molecular weight. , Maleic anhydride or maleic acid in an amount of 10 to 60 mol%, acrylic acid and / or
Or the combination which makes methacrylic acid 40-90 mol% is preferable. More preferably, maleic anhydride is added to 3
It is a combination of 0 to 50 mol% and 50 to 70 mol% of acrylic acid.

The sulfur-containing compound in the present invention is represented by the above general formula (1) or (2). Here, M is an alkali metal, an alkaline earth metal, or ammonia. Specific examples of M include lithium, sodium, potassium and the like as alkali metals, and alkaline earth metals as
Examples include calcium and magnesium. Of these, the case where M is an alkali metal, particularly sodium, is preferred because of its high reactivity.

A preferred example of the sulfur-containing compound represented by the general formula (1) is an alkali hydrosulfide salt. Specifically, for example, LiHSO ₃ , NaHS
Alkali hydrosulfide salts such as O ₃ , KHSO ₃ and (NH ₄ ) HS can be mentioned. In addition, the above general formula (1)
In the sulfur-containing compound represented by the formula, hydrates thereof can also be used. In addition, one kind may be used, or two or more kinds may be used in combination.

On the other hand, the sulfur-containing compound represented by the general formula (2)
Examples of the compound include sulfates, sulfites and alkali sulfates.
Can be mentioned. Specifically, Na_TwoSO_Three, Na
_TwoS _TwoO_Four, Na_TwoSO_Four, Na_TwoS_TwoO_ThreeSuch as sulfuric acid
Salt, sulfite, Li_TwoS, Na_TwoS, K_TwoS, (NH
_Four)_TwoAlkali sulfide salts such as S can be mentioned.
Further, the compound represented by the general formula (2) includes
Both hydrates and hydrates can be used.
Is preferred. One type may be used, or two or more types may be combined.
They may be used together.

It is to be noted that the alkali sulfide salt or the hydrogen sulfide
The salt may optionally be present in the reaction system in the presence of an alkali.
Hydrogen sulfide may be introduced underneath to generate. Said one
Among the sulfur-containing compounds represented by the general formula (1) or (2)
And NaHSO _Three, Na_TwoSO_Three, Na_TwoS_TwoO_Four, N
a_TwoSO_Four, Na_TwoS_TwoO_ThreeOr Na_TwoS is preferred
You.

In the present invention, the amount of the sulfur-containing compound to be added is preferably 0.1 to 0.1% based on all monomers to be subjected to polymerization.
３０30% by weight. More preferably, 0.5 to 20
% By weight. More preferably, it is 0.8 to 15% by weight. In addition, all monomers used for superposition | polymerization mean monoethylenically unsaturated carboxylic acid and maleic anhydride or maleic acid. If it exceeds 30% by weight, the calcium-scavenging ability may decrease. In addition, calcium capturing ability, 20 mg of a precisely weighed polymer was placed in a 200 ml beaker, and Ca ion concentration containing ammonium chloride 0.1 N, potassium chloride 0.1 N, and ammonia 0.4 N was 40 ppm. 100 g of an aqueous solution is dissolved therein.
Using a Ca ion electrode at 25 ° C., the concentration of divalent Ca ions in the aqueous solution was measured, converted into CaCO ₃ captured by 1 g of the polymer, and the calcium capturing ability (mg · C
aCO ₃ / g). 0.1% by weight
If it is less than 1, unreacted maleic acid may remain.

In the present invention, there is no particular limitation on the method of copolymerizing the above-mentioned monomers. However, specifically, in the case of carrying out the first invention, polymerization methods A, B and C described below are exemplified. can do. (Polymerization method A) A monoethylenically unsaturated carboxylic acid monomer and maleic acid or maleic anhydride in an aqueous medium in the presence of a sulfur-containing compound, an alkali, a thiol compound and / or a derivative thereof and a perethylenically unsaturated dicarboxylic acid. A method of copolymerizing an acid.

As the aqueous medium used in the polymerization method A, water or alcohol can be used. Of these, water is preferred. In the polymerization method A,
As the sulfur-containing compound, a sulfur-containing compound represented by the general formula (1) or (2) is used. Examples of the alkali used in the polymerization method A include hydroxides of alkali metals such as lithium hydroxide, sodium hydroxide, and potassium hydroxide, and ammonia.

It is advantageous to select the amount of the alkali to be used in a ratio of 0.5 to 1.1 equivalent to 1 equivalent of an acid group such as a carboxyl group in the raw material. Incidentally, the perethylenically unsaturated dicarboxylic acid usually has a -COOH group and a -COOOH group in the molecule, but the latter -COOOH group.
The group is not considered an acid group. Therefore, in the perethylenically unsaturated dicarboxylic acid, usually 1 mol per mol thereof is used.
It will have moles of acid groups (carboxyl groups).

The thiol compound used in the polymerization method A includes, for example, a general formula (3) HS-RY (3) wherein R is an alkylene group having 1 to 20 carbon atoms, and Y is hydrogen. _{atom, -OH, -NH 2, -COOH,} -SH, -O-
R ¹ or —SR ¹ (R ¹ is an alkyl group having 1 to 10 carbon atoms). The compound represented by these is preferable.

In the general formula (3), the alkylene group having 1 to 20 carbon atoms represented by R is linear, branched,
They may be cyclic, and specific examples thereof include methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene,
Examples include a decylene group, a dodecylene group, a cyclopentylene group, and a cyclohexylene group. Further, the alkyl group having 1 to 10 carbon atoms represented by R ¹ is linear, branched,
It may be cyclic, and specific examples include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a cyclopentyl group, and a cyclohexyl group.

Examples of such thiol compounds include:
Examples include aminoethanethiol, decanedithiol, cyclohexanethiol, cyclopentanethiol, di (2-mercaptoethyl) ether, ethanedithiol, heptanethiol, propanedithiol, thioglycolic acid, mercaptoethanol, and the like. Examples of the thiol compound derivatives include, for example, half esters of these thiol compounds with ethylenically unsaturated dicarboxylic acids. These thiol compounds and derivatives thereof may be used alone or in a combination of two or more.

The amount of the thiol compound to be used is generally selected in the range of 1 to 30% by weight, preferably 5 to 20% by weight, more preferably 5 to 15% by weight, based on the total amount of the monomers used. In the case of a derivative of a thiol compound, the derivative may be in the above range in terms of a thiol compound. Next, the perethylenically unsaturated dicarboxylic acid used in the polymerization method A has an action as a polymerization initiator. Examples of the perethylenically unsaturated dicarboxylic acid include the general formula (4)

[0024]

Embedded image

Wherein R ² represents a hydrogen atom, a methyl group or a carboxyl group; R ³ represents a carboxyl group when R ² is a hydrogen atom or a methyl group; and a hydrogen atom when R ² is a carboxyl group. Are preferable.) The compound represented by the formula: Examples of such perethylenically unsaturated dicarboxylic acids include permaleic acid, percitraconic acid, peritaconic acid and the like. This perethylenically unsaturated dicarboxylic acid is preferably produced by a reaction between an ethylenically unsaturated dicarboxylic acid and hydrogen peroxide, particularly a reaction between an acid anhydride and hydrogen peroxide. For example, it is advantageous to produce the compound by reacting maleic anhydride, citraconic anhydride, itaconic anhydride and the like with hydrogen peroxide. Among them, a reaction product of maleic anhydride and hydrogen peroxide is preferred.

At this time, it is desirable that hydrogen peroxide be used in a substantially stoichiometric amount with respect to the acid anhydride. That is,
It is preferable to use about 0.95 to 1.05 mol of hydrogen peroxide per 1 mol of the acid anhydride. Also, as hydrogen peroxide,
Usually, a hydrogen peroxide solution having a concentration of 25 to 75% by weight, preferably a hydrogen peroxide solution having a concentration of 30 to 70% by weight is used. The reaction between the acid anhydride and the aqueous hydrogen peroxide is preferably performed at a temperature of 20 to 60 ° C. for about 1 minute to 5 hours.

Since this perethylenically unsaturated dicarboxylic acid serves as a polymerization initiation point and radical polymerization proceeds, one end of the obtained monoethylenically unsaturated dicarboxylic acid copolymer is Residue. The molecular weight of the polymer can be adjusted by changing the amount of the perethylenically unsaturated dicarboxylic acid used. The perethylenically unsaturated dicarboxylic acids may be used alone or in combination of two or more. The amount used is usually 0.1 to 2.0 mol, preferably 1 mol of the monoethylenically unsaturated carboxylic acid monomer.
It is selected in the range of 0.5 to 1.5 mol.

In the polymerization method A, the compound represented by the general formula (1)
, A sulfur-containing compound, an aqueous solution containing an alkali, a thiol compound and / or a derivative thereof, a perethylenically unsaturated dicarboxylic acid, a monoethylenically unsaturated carboxylic acid, and maleic acid or maleic anhydride. Advantageously, it is added and polymerized. In this case,
The thiol compound or a derivative thereof may be added after being dissolved in an aqueous solution containing an alkali.

On the other hand, when a sulfur-containing compound represented by the general formula (2) is used, for example, an aqueous solution containing an alkali, an aqueous solution containing an alkali, a perethylenically unsaturated dicarboxylic acid, Monoethylenically unsaturated carboxylic acid and maleic acid or maleic anhydride are added and polymerized respectively, aqueous solution containing alkali sulfide or alkali hydrosulfide, aqueous solution containing alkali, perethylenically unsaturated dicarboxylic acid, A method in which ethylenically unsaturated carboxylic acid and maleic acid or maleic anhydride are simultaneously added to the reaction system to carry out polymerization, and hydrogen sulfide is introduced into an aqueous solution containing an alkali sulfide or an alkali hydrosulfide, or an aqueous solution containing an alkali. Together with perethylenically unsaturated dicarboxylic acid, monoethylenically unsaturated carboxylic acid and maleic acid. Maleic anhydride, a method for respectively adding the polymerization, and the like.

The polymerization temperature in the polymerization method A is not particularly limited, but is usually 30 to 130 ° C., preferably 60 to 1 ° C.
It is selected in the range of 10 ° C. Further, the polymerization time depends on the temperature and the like and cannot be unconditionally determined, but usually about 10 minutes to 10 hours is sufficient. In the polymerization method A, a method in which maleic acid or maleic anhydride and a part of alkali are charged in a reactor in advance, and then the remaining raw materials are simultaneously added to the reaction system to polymerize, respectively, is a method of capturing calcium. This is preferable from the viewpoint of the balance between the biodegradability and the biodegradation rate. (Polymerization method B) A method in which the above monomer is copolymerized with a non-oxidizing polymerization initiator in the presence of a sulfur-containing compound, a thiol compound having a hydroxyl group or an amino group. (Polymerization method C) A method in which the above monomers are copolymerized with a non-oxidizing polymerization initiator in the presence of a sulfur-containing compound, a thiol compound having a hydroxyl group or an amino group, and an inorganic or organic acid.

As the sulfur-containing compound in the polymerization method B or C, a sulfur-containing compound represented by the general formula (1) or (2) is used. Examples of the thiol compound having a hydroxyl group or an amino group in the polymerization method B or C include:
Formula HS-R-Y ··· (5 ) wherein the following, R represents an alkylene group having 1 to 20 carbon atoms, Y is a hydrogen atom, -OH, an -NH _2. The compound represented by these is preferable.

In the general formula (5), the alkylene group having 1 to 20 carbon atoms represented by R is linear, branched,
They may be cyclic, and specific examples thereof include methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene,
Examples include a decylene group, a dodecylene group, a cyclopentylene group, and a cyclohexylene group. Further, the alkyl group having 1 to 10 carbon atoms represented by R ¹ is linear, branched,
It may be cyclic, and specific examples include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a cyclopentyl group, and a cyclohexyl group.

Examples of such thiol compounds include:
Aminoethanethiol, decanedithiol, cyclohexanedithiol, cyclopentanedithiol, di (2-
Mercaptoethyl) ether, ethanedithiol, heptanedithiol, propanedithiol, thioglycolic acid, mercaptoethanol and the like. Examples of the thiol compound derivatives include, for example, half esters of these thiol compounds with ethylenically unsaturated dicarboxylic acids. These thiol compounds and derivatives thereof may be used alone or in a combination of two or more.

These organic thiol compounds are usually used in an amount of 1 to 30% by weight based on the unsaturated carboxylic acid monomer.
Preferably, an amount in the range of 5 to 25% by weight is used. If this amount exceeds 30% by weight, the chelating ability tends to be insufficient. As the inorganic acid or organic acid in the polymerization method C, concentrated sulfuric acid, boric acid, phosphoric acid, p-toluenesulfonic acid, p-bromobenzenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, nonafluorobutanesulfonic acid, 2,2,2-trifluoroethanesulfonic acid and the like can be mentioned. Among these inorganic or organic acids, concentrated sulfuric acid, sulfurous acid, boric acid, phosphoric acid, p-toluenesulfonic acid, and methanesulfonic acid can be suitably used.

These inorganic or organic acids are generally used in an amount of 0.1 to 10% by weight, preferably 1 to 10% by weight, based on the monomer.
An amount ranging from 範 囲 5% by weight is used. If this amount is 10
If the content exceeds% by weight, cloudiness tends to occur. Polymerization method B
Alternatively, in C, examples of the non-oxidizing polymerization initiator include azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobiscyclohexanecarbonitrile, tetramethylthiuram disulfide and the like.

Further, photopolymerization such as ultraviolet rays can also be mentioned as a polymerization method using a non-oxidizing polymerization initiator. At this time, a photosensitizer may be added as needed. Among these non-oxidizing polymerization initiators, azobisisobutyronitrile can be suitably used. These non-oxidizing polymerization initiators are usually added to the unsaturated carboxylic acid monomer at a ratio of 0.1 to 0.1.
An amount in the range of 1 to 5.0% by weight, preferably 0.5 to 2.0% by weight is used.

In the polymerization method B or C, the copolymerization is usually carried out using no solvent or a non-aqueous solvent. Examples of the non-aqueous solvent include acetone, dimethylformamide, dimethylacetamide, ethyl acetate, N-methylpyrrolidone, benzene, toluene, xylene, dioxane and the like. Polymerization is preferably carried out without solvent, but when a non-aqueous solvent is used, acetone is preferred.

Further, the reaction conditions are not particularly limited with regard to the polymerization pressure, and usually, the pressure is from atmospheric pressure to 10 kg / cm ^2.
G, preferably from atmospheric pressure to 5 kg / cm ² G, and the polymerization temperature is appropriately selected in the range of usually 30 to 150 ° C, preferably 50 to 100 ° C. The polymerization time depends on the raw materials, the polymerization temperature and the like, and cannot be determined unconditionally.
The time is from about minutes to 20 hours, preferably about 1 to 4 hours.

The reaction method in the polymerization method B or C is not particularly limited, and a solution of an unsaturated carboxylic acid monomer, a non-oxidizing polymerization initiator and a non-aqueous solvent may be used.
A method in which a solution of an organic thiol compound and a non-aqueous solvent is added dropwise to a heated and stirred reactor, and a reaction is performed.A solution of an unsaturated carboxylic acid monomer and a non-aqueous solvent is placed in a reactor and heated and stirred. And a solution of an inorganic acid or an organic acid, a solution of an organic thiol compound, a non-oxidizing polymerization initiator and a non-aqueous solvent are dropped into a heated and stirred reactor, respectively. And a reaction method.

In the second invention, the method of adding the sulfur-containing compound is not particularly limited, but is added after the completion of the polymerization reaction. The timing of the addition depends on the reaction conditions such as the type of the initiator, the temperature and the monomer concentration, and cannot be unambiguously determined. However, it is preferable to add the monomer one hour after the completion of the dropwise addition of the entire amount of the monomer. When azoisobutyronitrile is used as the initiator, the reaction efficiency is high. Therefore, it is preferable to add the monomer 0.5 hours after the completion of the dropping of the whole amount. The addition amount is preferably 0.1 to 30% by weight based on all monomers used for the polymerization. More preferably,
It is 0.5 to 20% by weight. More preferably, 0.8 to
15% by weight. If it exceeds 30% by weight, the calcium scavenging ability will be reduced, and if it is less than 0.1% by weight, unreacted maleic acid may remain. The term "all monomers used for polymerization" refers to monoethylenically unsaturated carboxylic acid and maleic anhydride or maleic acid.

The reaction temperature in the second invention is not particularly limited, but is usually 30 to 130 ° C., preferably 60 to 110 ° C.
It is selected in the range of ° C. The reaction time depends on the temperature and the like and cannot be determined unconditionally.
About 0 minutes to 10 hours is sufficient.

[0042]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In addition, the obtained copolymer was evaluated according to the following procedure. (1) Number average molecular weight Polyacrylic acid was measured by gel permeation chromatography (GPC) as a standard substance.

The measuring conditions were as follows: Waters AL
C / GPC 150C device (Detector: built-in differential refractometer,
Column: ASAHIPAK (GF-310HQ + GF-
7MHQ), the mobile phase was 1 mM NaH ₂ PO ₄ aqueous solution / 7 mM Na ₂ HPO ₄ aqueous solution = 1/1, the column temperature was 40 ° C., the flow rate was 0.7 ml / min, and the injection volume was 200 μl. (2) Method for quantifying maleic acid After completion of the reaction using a GSX-400 device manufactured by JEOL Ltd.,
The polymer obtained by freeze-drying was dissolved in a heavy water solvent to a polymer concentration of 5
The solution was adjusted to less than the weight percentage. The prepared solution placed in a test tube having a diameter of 5 mm, at room temperature, 400MH _Z, SGN
In the ON mode, ¹ H-NMR measurement was performed by integrating 32 times, and the amount of unreacted residual maleic acid was quantified from the absorption peak of the double bond of unreacted maleic acid. Example 1 A stirrer, a reflux condenser, a thermocouple, and a chemical pump (for feeding raw materials) were set in a 100-ml separable flask. 3.92 g of maleic anhydride
(0.04 mol) and 2.27 g of 60% aqueous hydrogen peroxide (0.
04 mol), and permaleic acid was synthesized in advance. Acrylic acid 2.8 was added to this aqueous solution of maleic acid while stirring.
g (0.04 mol) was added. 1.35 g of water was put into the separable flask so that the final (after the reaction) monomer concentration (acrylic acid + maleic acid) became 55% by weight.
The mixed solution was dropped into the separable flask heated to 100 ° C. over 1 hour through a chemical pump.
At the same time, a predetermined amount of aqueous sodium hydroxide solution (5
0.86 g (0. 0 wt%) of mercaptoethanol.
(011 mol) was added dropwise to the separable flask over 1 hour using a chemical pump to carry out a polymerization reaction. After completion of the dropwise addition, a polymerization reaction was carried out at 100 ° C. for 1 hour, and 0.11 g of NaHSO ₃ (0.0009 m
ol) and reacted for 1 hour. After completion of the reaction, the desired product was obtained by freeze-drying. Table 1 shows the amount of unreacted residual maleic acid and the number average molecular weight of the obtained polymer. Substituting the Example 2-Example 5 NaHSO ₃ with a compound described in Table 1, except that the addition amount was equal 0.0009mol and NaHSO _3, was performed in the same manner as in Example 1. Table 1 shows the amount of unreacted residual maleic acid and the number average molecular weight of the obtained polymer. Example 6 A stirrer, a reflux condenser, a thermocouple, and a chemical pump (for feeding raw materials) were set in a 100-ml separable flask. 3.92 g of maleic anhydride
(0.04 mol) and 2.27 g of 60% aqueous hydrogen peroxide (0.
04 mol), and permaleic acid was synthesized in advance. Acrylic acid 2.8 was added to this aqueous solution of maleic acid while stirring.
g (0.04 mol) was added. 1.35 g of water was put into the separable flask so that the final (after the reaction) monomer concentration (acrylic acid + maleic acid) became 55% by weight.
The mixed solution was dropped into the separable flask heated to 100 ° C. over 1 hour through a chemical pump.
At the same time, a predetermined amount of aqueous sodium hydroxide solution (5
0.86 g (0.0 wt%) of mercaptoethanol.
11 mol) and 0.11 g (0.001 g) of sodium sulfide
(4 mol) was added dropwise to a separable flask over 1 hour using a chemical pump to carry out a polymerization reaction. After completion of the dropwise addition, a polymerization reaction was performed at 100 ° C. for 1 hour.
Table 1 shows the amount of unreacted residual maleic acid and the number average molecular weight of the obtained polymer. Example 7 Maleic anhydride 4 was placed in a 500 ml separable flask equipped with a stirrer and a thermocouple.
9.5 g, 1.0 g (0.008 mol) of NaHSO ₃ and 15 g of acetone were added, and the mixture was heated in a 110 ° C. oil bath. Separately, a solution prepared by adding 9.8 g of mercaptoethanol and 4.8 g of azoisobutyronitrile to 43.2 g of acrylic acid and 15 g of acetone was dropped into the separable flask over 30 minutes. After dropping,
Heating and stirring were continued for another 2 hours. Table 1 shows the amount of unreacted residual maleic acid and the number average molecular weight of the obtained polymer. Substituting the Example 8 - Example 11 NaHSO ₃ with a compound described in Table 1, except that the addition amount was equal 0.008mol with NaHSO _3, was performed in the same manner as in Example 7. Table 1 shows the amount of unreacted residual maleic acid and the number average molecular weight of the obtained polymer. Example 12 Capacity 500 with Stirrer and Thermocouple
In a milliliter separable flask were placed 49.5 g of maleic anhydride and 1.0 g of NaHSO ₃ (0.008 mol).
l) and 15 g of acetone were added and heated in an oil bath at 110 ° C. On the other hand, concentrated sulfuric acid 1.0 to 43.2 g of acrylic acid
g, a solution prepared by adding 15 g of acetone to 9.8 g of mercaptoethanol and 4.8 g of azoisobutyronitrile was dropped into a separable flask with stirring over 30 minutes. After completion of the dropwise addition, heating and stirring were continued for another 2 hours. Table 1 shows the amount of unreacted residual maleic acid and the number average molecular weight of the obtained polymer. Substituting the Example 13 ~ Example 16 NaHSO ₃ with a compound described in Table 1, except that the addition amount was equal 0.008mol with NaHSO _3, was performed in the same manner as in Example 12. Table 1 shows the amount of unreacted residual maleic acid and the number average molecular weight of the obtained polymer. [Comparative Example 1] An experiment was performed in the same manner as in Example 1 except that NaHSO ₃ was not used. Table 1 shows the amount of unreacted residual maleic acid and the number average molecular weight of the obtained polymer. [Comparative Example 2] The same operation as in Example 1 was carried out except that NaHSO ₃ was not used. Table 1 shows the amount of unreacted residual maleic acid and the number average molecular weight of the obtained polymer.

[0044]

[Table 1]

[0045]

The monoethylenically unsaturated carboxylic acid copolymer obtained according to the present invention contains no unreacted residual maleic acid and is therefore suitable as a biodegradable builder, a biodegradable dispersant and a detergent composition. Used for The monoethylenically unsaturated carboxylic acid copolymer obtained in the present invention is used as a biodegradable builder or a biodegradable dispersant by being isolated or solidified by means of freeze-drying or the like as it is. be able to. Further, the monoethylenically unsaturated carboxylic acid copolymer obtained according to the present invention has a chelating ability and is therefore useful as a scale inhibitor in cooling water systems, boiler water systems and the like.

Claims (5)

[Claims] 1. A copolymerization reaction between a monoethylenically unsaturated carboxylic acid and maleic anhydride or maleic acid in the presence of a sulfur-containing compound represented by the following general formula (1) or (2): For producing a monoethylenically unsaturated carboxylic acid copolymer. _{M n H S a O b ···} (1) (M is an alkali metal, alkaline earth metal or ammonium, n represents 1 or 1/2, a is 1 or 2, and b is 0 or 3 _{) M m S a O b ···} (2) (M is an alkali metal, alkaline earth metal or ammonium, m is 1 or 2, a is 1 or 2, and b
Is 0, 3 or 4, and when b is 0, a is 1) 2. A copolymerization reaction between a monoethylenically unsaturated carboxylic acid and maleic anhydride or maleic acid, followed by adding a sulfur-containing compound represented by the following general formula (1) or (2) to carry out the reaction. A method for producing a monoethylenically unsaturated carboxylic acid copolymer. _{M n H S a O b ···} (1) (M is an alkali metal, alkaline earth metal or ammonium, n represents 1 or 1/2, a is 1 or 2, and b is 0 or 3 _{) M m S a O b ···} (2) (M is an alkali metal, alkaline earth metal or ammonium, m is 1 or 2, a is 1 or 2, and b
Is 0, 3 or 4, and when b is 0, a is 1) 3. The method according to claim 1, wherein the sulfur-containing compound is NaHSO ₃ , Na ₂
SO ₃ , Na ₂ S ₂ O ₄ , Na ₂ SO ₄ , Na ₂ S ₂ O
_The method for producing a monoethylenically unsaturated carboxylic acid copolymer according to claim 1 or 2, which is ₃ or Na ₂ S. 4. The amount of the sulfur-containing compound added is 0.1 to 30% by weight based on the total amount of the monomers subjected to the polymerization.
4. The method for producing a monoethylenically unsaturated carboxylic acid copolymer according to any one of claims 1 to 3. 5. The method for producing a monoethylenically unsaturated carboxylic acid copolymer according to claim 1, wherein the monoethylenically unsaturated carboxylic acid is acrylic acid or methacrylic acid.