JPH10204119A - Method for modifying water-soluble polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polymer having structural units typified by α- hydroxyacrylic acid simply by modifying a water-soluble polymer typified by polyacrylic acid in the presence of a metal salt and hydrogen peroxide. SOLUTION: A water-soluble polymer comprising structural units represented by formula I or II [R<1> is hydrogen, methyl or COOX<1> (X<1> is hydrogen, an alkyl, an alkali metal atom or an ammonium group; and Y<1> is an aldehydo, cyano, an amido or an imido)] is modified in the presence of a metal salt and hydrogen peroxide into a polymer having structural units represented by formula III or IV (R<1> , X<1> and Y<1> are as defined above). The water-soluble polymer is desirably a polymer having structural units being at least one type of residues of monomers selected from the group consisting of acrylic acid, maleic acid, fumaric acid, maleic anhydride and salts thereof. The metallic salt used is desirably a salt of especially Fe, Cu, V or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for modifying a water-soluble polymer. More specifically, the present invention relates to a modification method for enhancing the usefulness of a water-soluble polymer mainly used for a biodegradable builder, a dispersant, a scale inhibitor and the like.

[0002]

2. Description of the Related Art Conventionally, a water-soluble polymer having a structural unit of α-hydroxyacrylic acid has the preferable characteristics of poly-α-hydroxyacrylic acid, and therefore is used as a chelating agent, a dispersant, and a scale inhibitor. Used in As a method for producing this polymer, a monomer obtained by chlorinating the α-position of acrylic acid and acrylic acid are copolymerized,
Thereafter, a method of introducing a structural unit of α-hydroxyacrylic acid by hydrolysis is adopted.

In such a method, a step of chlorinating the α-position of acrylic acid, a step of hydrolyzing after copolymerization, and the like are required, so that the cost of raw materials is high and the equipment cost is also high. There is a demand for a simple and inexpensive polymerization method.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to obtain a polymer having a structural unit represented by .alpha.-hydroxyacrylic acid by a simple method.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies on the above problems, and as a result, have found that a polymer having a structural unit represented by α-hydroxyacrylic acid can be obtained by a simple method. Completed the invention. That is, the present invention has the general formula (I) or (II)

[0006]

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(Wherein R ¹ is a hydrogen atom, a methyl group or a C
OOX ¹ , wherein X ¹ represents a hydrogen atom, an alkyl group, an alkali metal atom or an ammonium group. Y ¹ is
It represents an aldehyde group, a cyano group, an amide group, or an imide group. A) a water-soluble polymer comprising a structural unit represented by the general formula (III) or (IV) in the presence of a metal salt and hydrogen peroxide.

[0008]

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(Wherein R ¹ is a hydrogen atom, a methyl group or a C
OOX ¹ , wherein X ¹ represents a hydrogen atom, an alkyl group, an alkali metal atom or an ammonium group. Y ¹ is
It represents an aldehyde group, a cyano group, an amide group, or an imide group. The present invention provides a method for modifying a water-soluble polymer, which comprises modifying the polymer having a structural unit represented by the formula (1). As the water-soluble polymer, a polymer having at least one selected from the group consisting of residues of acrylic acid, maleic acid, fumaric acid, and maleic anhydride and salts thereof as a constituent unit is preferable.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The method for modifying a water-soluble polymer of the present invention is represented by the general formula (I) or (II):

[0011]

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A water-soluble polymer comprising the structural unit represented by the general formula (III) or (III) in the presence of a metal salt and hydrogen peroxide.
(IV)

[0013]

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It is characterized by being modified into a polymer having a structural unit represented by the formula: The above general formula (I)
In (IV), R ¹ is a hydrogen atom, a methyl group or COOX
^And X ¹ represents a hydrogen atom, an alkyl group, an alkali metal atom or an ammonium group. Y ¹ represents an aldehyde group, a cyano group, an amide group, or an imide group. In addition,
As the alkyl group, a methyl group and an ethyl group are preferable,
As the alkali metal atom, sodium or potassium is preferable.

The water-soluble polymer in the present invention includes acrylic acid, maleic acid, maleic anhydride, fumaric acid, methacrylic acid, itaconic acid, itaconic anhydride, crotonic acid, maleic amide, maleic imide, vinyl acetate, Acrylic ester, methacrylic acid ester, acrylonitrile and the like and the target is a polymer containing a salt thereof in the structural unit, and at least the structural unit represented by the above general formula (III) or (IV) It must include what can be done. Preferable examples thereof include a polymer having at least one member selected from the group consisting of residues of acrylic acid, maleic acid, fumaric acid, and maleic anhydride and salts thereof, and structural units of methacrylic acid and salts thereof. Examples of the polymer include a polymer having at least one of a structural unit of a group consisting of residues of maleic acid, fumaric acid, and maleic anhydride and salts thereof. In particular, polyacrylic acid is preferred.

The metal salts used in the modification method of the present invention include Fe, Cu, V, Ni, Co, Mn, Ce and Zn.
And the like. Specifically, ferrous sulfate heptahydrate, ferrous chloride, ferrous acetate, ferrous phosphate, ferric sulfate, ferric chloride, ferric phosphate, cuprous acetate, Cuprous chloride, cuprous bromide, cupric nitrate, cupric acetate, cupric chloride, cupric bromide, vanadium sulfate, vanadium trichloride, vanadium oxytrichloride, vanadium pentoxide, copper powder , Iron powder, nickel nickel acetate
Preferable examples include tetrahydrate, zinc acetate / dihydrate, cerium acetate / monohydrate, cobaltous acetate / tetrahydrate, and manganese acetate. Among these, Fe, C
u and V are preferable, and may be selected from the above specific examples containing the respective metal components. These may be used alone or in combination of two or more.

These metal salts are used in an amount of usually 5 to 1000 ppm (weight), preferably, to the water-soluble polymer.
It is preferably used in the range of 10 to 300 ppm (weight). If less than this range, the desired effect cannot be obtained,
On the other hand, if the amount is too large, a problem occurs that the polymer is colored. Also,
The hydrogen peroxide used in the modification method of the present invention is usually 25 to 75% by weight aqueous hydrogen peroxide, and preferably 3% by weight.
0 to 70% by weight aqueous hydrogen peroxide.

The hydrogen peroxide is used in an amount of usually 0.5 to 1.5 mol, preferably 0.1 to 1 mol, per mol of the water-soluble polymer.
It is preferable to use 8 to 1.2 mol. In the method for modifying the water-soluble polymer of the present invention, it is preferable to use water as a reaction solvent. When denaturing, the concentration of the water-soluble polymer is
Usually 20 to 80% by weight, preferably 40 to 70% by weight
Should be within the range. Further, the pH of the denaturation reaction field is preferably controlled so as to be usually in the range of 2 to 14, preferably 7-14. By setting it in this range, the introduction ratio of the hydroxyl group is increased. Specifically, a method is employed in which sodium hydroxide, potassium hydroxide, ammonium hydroxide, or the like is added directly or as an aqueous solution, if necessary.

The denaturation (reaction) temperature is not particularly limited, but is usually controlled to be in the range of 20 to 120 ° C., preferably 40 to 100 ° C. By adopting the production method as described above, the structural unit represented by the general formula (III) or (IV) is usually added in an amount of 5 mol% or more, preferably 1 mol% or more.
A polymer having 0 mol% or more can be obtained by a simple method.

[0020]

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 weight average molecular weight, the amount of hydroxyl groups introduced, and the degree of neutralization of the modified product were determined by the following methods. (1) Measurement of weight average molecular weight (Mw) Polyacrylic acid was measured by gel permeation chromatography (GPC) using polyacrylic acid as a standard substance. As the measurement conditions, ALC / GPC 1 manufactured by Waters, Inc.
50C device (detector: RI detector, column: ASAHI)
Using PAK (GSM-700 + GS310), the mobile phase was acetonitrile / 50 mM sodium acetate = 3 /
7, the column temperature is 40 ° C., the flow rate is 0.7 ml / min,
The injection volume was 200 μl.

(2) Quantification of the amount of introduced hydroxyl groups For the modified product comprising the structural units of acrylic acid and α-hydroxyacrylic acid as in the following examples, the amount of introduced hydroxyl groups was calculated from the elemental analysis values by the following formula. did. Hydroxyl group introduction amount (mol%) = 549.45-10.99 × XX XX indicates an elemental analysis value (% by weight) of carbon in the modified product. This equation is based on the fact that the elemental analysis value of carbon in polyhydroxyacrylic acid measured under the same conditions is 40.9% by weight and the elemental analysis value of carbon in polyacrylic acid is 50.0% by weight. (3) Degree of neutralization The degree of neutralization was calculated from the number of moles of sodium hydroxide added and the number of moles of acrylic acid units in polyacrylic acid during the denaturation reaction.

Example 1 A 100-ml separable flask equipped with a stirrer, a reflux condenser, and a chemical pump was charged with polyacrylic acid (manufactured by Aldrich Co., Ltd.).
(Weight average molecular weight: 2700): 7.2 g, FeCl _2.
4H ₂ 0: 1.3 mg, CuCl: 0.6 mg, water:
4.8 g was added, immersed in an oil bath at 80 ° C., and uniformly dissolved. There, 5.67 g of a 60% aqueous hydrogen peroxide solution was added dropwise over 1 hour. Thereafter, the temperature was maintained at 80 ° C. for 1 hour to complete the reaction. After completion of the reaction, freeze-drying was performed to obtain a denatured product. The molecular weight and the amount of hydroxyl groups introduced are
It is shown in the table.

This was prepared by DEPT using ¹³ C-NMR.
As a result of measurement by the method, 87 in the DEPT chart
The disappearance of the peak at ~ 88 ppm confirmed the presence of quaternary carbon in the modified product. Further, since the chemical shift of this peak is 87 to 88 ppm,
This quaternary carbon is considered to have a hydroxyl group bonded at the α-position of the carboxyl group.

FIG. 1 shows an IR chart of this product after methyl esterification. It can be seen from the large absorption around 3500 cm ^{-1 that a} hydroxyl group has been introduced.
In addition, methyl esterification was performed as follows. 100
In a milliliter eggplant-shaped flask, the above modified product: 0.5
g, 14 ml of methanol and 25 ml of benzene were added and dissolved. While cooling the flask with ice, add 2
M-trimethylsilyldiazomethane-hexane solution:
5.0 ml was slowly added dropwise. After completion of the dropwise addition, the reaction solution was reacted at room temperature for 3 hours. After completion of the reaction, the solvent was distilled off,
The sample was dried under reduced pressure to obtain a sample for an IR chart. Example 2 FeCl ₂ .4H ₂ 0 in Example 1
1.3 mg CuCl: 0.6 mg VOSO ₄ .nH
₂ O (70% purity): was replaced 0.6mg were performed in the same manner as in Example 1. The results are shown in Table 1. Example 3 FeCl ₂ .4H ₂ 0 in Example 1
1.3 mg CuCl: 0.6 mg VOSO ₄ .nH
₂ O (purity 70%): The same operation as in Example 1 was performed except that the reaction temperature was changed to 3.3 mg and the reaction temperature was changed from 80 ° C to 40 ° C. The results are shown in Table 1.

Example 4 A 100 ml separable flask equipped with a stirrer, a reflux condenser, and a chemical pump was charged with polyacrylic acid (manufactured by Aldrich Co., Ltd.).
(Weight average molecular weight: 2700): 7.2 g, FeCl _2.
4H ₂ 0: 1.3 mg, CuCl: 0.6 mg, water:
4.8 g and sodium hydroxide: 0.50 g were added, and 8
It was immersed in an oil bath at 0 ° C. and uniformly dissolved. there,
5.67 g of 60% aqueous hydrogen peroxide was added dropwise over 1 hour. Thereafter, the temperature was maintained at 80 ° C. for 1 hour to complete the reaction. After completion of the reaction, freeze-drying was performed to obtain a denatured product. Table 1 shows the molecular weight and the amount of OH introduced. Example 5 Sodium hydroxide in Example 4: 0.1.
The same operation as in Example 4 was performed except that 5 g was replaced with 3.15 g. The results are shown in Table 1.

[0026]

[Table 1]

[0027]

According to the present invention, a polymer having a structural unit represented by α-hydroxyacrylic acid can be obtained by a simple method. The number of reaction steps is small, and the equipment cost can be reduced, which is industrially advantageous.

[Brief description of the drawings]

FIG. 1 shows an IR chart of Example 1.

Claims (2)

[Claims] 1. A compound of the general formula (I) or (II) (Wherein, R ¹ represents a hydrogen atom, a methyl group, or COOX ¹ , X ¹ represents a hydrogen atom, an alkyl group, an alkali metal atom, or an ammonium group. Y ¹ represents an aldehyde group, a cyano group, an amide group. Or an imide group) in the presence of a metal salt and hydrogen peroxide, in the presence of a structural unit represented by the general formula (III) or (IV): (Wherein, R ¹ represents a hydrogen atom, a methyl group, or COOX ¹ , X ¹ represents a hydrogen atom, an alkyl group, an alkali metal atom, or an ammonium group. Y ¹ represents an aldehyde group, a cyano group, an amide group. Or a imide group.) A method for modifying a water-soluble polymer, characterized in that the polymer has a structural unit represented by the formula: 2. The water-soluble polymer is a polymer having at least one selected from the group consisting of residues of acrylic acid, maleic acid, fumaric acid, and maleic anhydride and salts thereof as a constituent unit. Item 6. The method for modifying a water-soluble polymer according to Item 1.