JP2002308934A - Method for manufacturing (meth)acrylic acid (co)polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a (meth)acrylic acid (co)polymer permitting to simply and effectively decompose and reduce a hydroquinone compound contained in a monomer. SOLUTION: In manufacturing the (meth)acrylic acid polymer or copolymer by polymerizing a monomer comprising acrylic acid or methacrylic acid, or a salt thereof as an essential ingredient, a hydroquinone compound, a persulfate, a water-soluble metallic salt and hydrogen peroxide are caused to exist in the reaction system, the amount of the persulfate and the water-soluble metallic salt being 15-300 pts.wt. and 0.001-0.05 pt.wt., respectively, each based on 1 pt.wt. of the hydroquinone compound, and the persulfate/hydrogen peroxide molar ratio being 0.01-0.5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a polymer or copolymer of acrylic acid or methacrylic acid (hereinafter referred to as (meth) acrylic acid (co) polymer) useful as a detergent builder or the like.

[0002]

2. Description of the Related Art Hydroquinone compounds contained in monomers such as (meth) acrylic acid are used as polymerization inhibitors to improve the safety of monomers and the stability of quality. Often used for maintenance.

On the other hand, (meth) acrylic acid (co) polymers are used as builders in powder detergents for clothing. The powder detergent for clothing is obtained by drying an aqueous solution or slurry of a cleaning component such as a surfactant or an inorganic salt containing a (meth) acrylic acid (co) polymer at a high temperature of 200 ° C. or more. May cause significant coloration in the powder detergent. For example, Japanese Patent Application Laid-Open No. 62-121705
In the method of polymerizing acrylic acid described in Japanese Patent Application Laid-Open No. 11-315115 or JP-A-11-315115, a polymerization inhibitor remains in a (meth) acrylic acid (co) polymer, and a powder detergent using the same is remarkable. Pink coloring is observed.

Accordingly, when used as a detergent builder,
There is a need for a method for producing a (meth) acrylic acid (co) polymer with a reduced polymerization inhibitor so that a detergent powder without coloration can be obtained.

Using a monomer containing a small amount of a polymerization inhibitor, a (meth) acrylic acid (co) polymer having a reduced amount of the polymerization inhibitor can be obtained (JP-A-11-311).
No. 22846). However, this method has a problem in safety and stability during use and storage of the monomer because the polymerization inhibitor in the monomer is extremely small.

An object of the present invention is to provide a method for producing a (meth) acrylic acid (co) polymer which can easily and effectively decompose and reduce a hydroquinone compound contained in a monomer. It is.

[0007]

DISCLOSURE OF THE INVENTION The present invention relates to a method for producing a (meth) acrylic acid (co) polymer by polymerizing a monomer essentially comprising acrylic acid or methacrylic acid or a salt thereof. Inside, hydroquinone compound, persulfate,
A water-soluble metal salt and hydrogen peroxide are used in an amount of 15 to 300 parts by weight of a persulfate and 0.001 to 0.05 parts by weight of a water-soluble metal salt per 1 part by weight of a hydroquinone compound. This is a method for producing a (meth) acrylic acid (co) polymer in which a molar ratio of 0.01 to 0.5 is present.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [(Meth) acrylic acid (co) copolymer] The (meth) acrylic acid (co) polymer of the present invention is a (meth) acrylic acid (salt) polymer or (meth) acrylic acid (salt) polymer. It is a copolymer of acrylic acid (salt) and a monomer having a reactive unsaturated group copolymerizable therewith, and the ratio of (meth) acrylic acid (salt) to the total amount of monomers is 50 to 100. Mol%
Is preferably, and more preferably 60 to 100 mol%, and 90
-100 mol% is particularly preferred. By increasing the ratio of (meth) acrylic acid (salt), performance as a dispersant, a scale inhibitor, and a detergent builder is enhanced. Here, acrylic acid, methacrylic acid, or a mixture thereof can be used as the (meth) acrylic acid. The weight average molecular weight of the (meth) acrylic acid (co) polymer is 20
It is preferably from 00 to 1,000,000, more preferably from 5000 to 200,000.

The monomer (meth) acrylic acid (salt) may be unneutralized, partially or completely neutralized or overneutralized. Examples of the salt include alkali metal salts such as sodium and potassium, alkaline earth metal salts such as calcium and magnesium, ammonium salts, and organic amine salts such as monoethanolamine and triethanolamine. And at least one salt selected from the group consisting of magnesium and magnesium. These may be mixtures.

In the present invention, a monomer having (meth) acrylic acid (salt) as an essential component is used, but a monomer having a reactive unsaturated group copolymerizable with (meth) acrylic acid (salt) is used. They may be used together. Such monomers include maleic acid, itaconic acid, 2- (meth) acrylamide-2-
Anionic monomers such as propanesulfonic acid and p-styrenesulfonic acid or salts thereof, cationic monomers such as methacryloyloxytrimethylammonium chloride, N
-(3-sulfopropyl) -N- (meth) acryloyloxyethyl-N, N-dimethylammonium betaine, N- (3-sulfopropyl) -N- (meth) acryloylamidopropyl-N, N-dimethylammonium betaine Zwitterionic monomers such as acrylamide, N,
N-dimethylacrylamide, 2-hydroxyethyl acrylate, methoxy polyethylene glycol (meth)
Nonionic monomers such as acrylates, hydrophobic (meth) acrylates such as methyl acrylate, methyl methacrylate, polypropylene glycol (meth) acrylate, and hydrophobic (meth) such as t-butylacrylamide
Acrylamide and the like can be mentioned. Of these, anionic monomers or salts thereof are preferred.

[0011] Monomers such as (meth) acrylic acid (salt) often contain a hydroquinone compound as a polymerization inhibitor in order to maintain storage stability and safety. Such a hydroquinone compound is a compound having a hydroxyphenol skeleton, and preferably includes p-hydroxyphenol (hereinafter, referred to as hydroquinone) or p-methoxyphenol (hereinafter, referred to as methoquinone).

The hydroquinone compound used in the present invention is contained in a monomer, and the content of the hydroquinone compound in the monomer containing (meth) acrylic acid (salt) as an essential component is 50 to 300 mg. / Kg is preferred.

(Meth) obtained by the production method of the present invention
The content of the hydroquinone compound in the acrylic acid (co) polymer is preferably 10 mg / kg or less.
mg / kg or less, more preferably 5 mg / k.
g or less, and most preferably 1 mg / kg or less. There is no lower limit, but 0.00
It may be at least 01 mg / kg. When the (meth) acrylic acid (co) polymer having such a low content of the hydroquinone compound is blended in a powder detergent, coloring of the powder detergent can be suppressed.

[Production of (meth) acrylic acid (co) polymer] The solvent used in the polymerization reaction of the (meth) acrylic acid (co) polymer of the present invention is preferably an aqueous solvent, particularly preferably. Is water. Further, in order to improve the solubility of the above monomers in the solvent, an organic solvent may be appropriately added within a range that does not adversely affect the polymerization of each monomer.

As the organic solvent, specifically, at least one selected from the group consisting of lower alcohols such as methanol and ethanol; amides such as dimethylformamide; ethers such as diethyl ether and dioxane can be appropriately selected and used. it can.

In the present invention, one or more persulfates and hydrogen peroxide for accelerating the decomposition of the hydroquinone compound are added as an initiator system used for the polymerization.
These may be added simultaneously, but are preferably added separately, and more preferably, hydrogen peroxide is added after the addition of the persulfate.

The above-mentioned persulfate includes, specifically, at least one selected from sodium persulfate, potassium persulfate and ammonium persulfate.

The persulfate is used to promote the polymerization sufficiently, to suppress the coloration of the (co) polymer, and to reduce the quality of the detergent powder containing the (co) polymer. 1
It is preferable to add 0.3 to 6 parts by weight, more preferably 0.5 to 3 parts by weight, based on 00 parts by weight. The hydroquinone compound 1 present in the monomer
It is necessary to add 15 to 300 parts by weight of persulfate to the parts by weight, and it is preferable to add 25 to 150 parts by weight.

The molar ratio of persulfate to hydrogen peroxide, persulfate / hydrogen peroxide, is 0 to suppress the coloring of the (co) polymer and to promote the progress of the polymerization and the decomposition of the hydroquinone compound. 0.01 to 0.5, preferably 0.02 to 0.5.

Further, in the present invention, it is essential to add a trace amount of a water-soluble metal salt in order to increase the efficiency of decomposition and polymerization of the hydroquinone compound present in the reaction system. The addition of the water-soluble metal salt may be before or after the initiator, but is preferably before the initiator.

Examples of the water-soluble metal salt include at least one selected from the group consisting of iron compounds such as ferrous sulfate and ferrous chloride, and copper compounds such as cupric sulfate and cupric chloride. Ferrous sulfate and / or cupric sulfate are preferred.

The water-soluble metal salt efficiently decomposes the hydroquinone compound, suppresses the coloring of the (co) polymer, and further reduces the quality of the detergent containing the (co) polymer. 0.00 parts by weight
It is necessary to add 1 to 0.05 parts by weight, and 0.0
It is preferable to add 0.25 to 0.04 parts by weight.
It is more preferable to add 0035 to 0.02 parts by weight.

A chain transfer agent may be added to adjust the molecular weight of the (meth) acrylic acid (co) polymer. Specific examples of the chain transfer agent include thioglycolic acid, water-soluble mercaptans such as 2-mercaptoethanol, sodium hypophosphite, hypophosphites such as potassium hypophosphite,
Sulfites such as sodium sulfite and sodium hydrogen sulfite are included.

A monomer containing a hydroquinone compound and essentially containing (meth) acrylic acid (salt), a persulfate, a water-soluble metal salt, and hydrogen peroxide may be added in any order. The polymerization may be started after being added to the reaction system before the polymerization, or during the polymerization, the polymerization may be carried out by diluting in a solvent and adding the mixture to the reaction system all at once or continuously.
Preferably, the water-soluble metal salt is added before the addition of the monomer. Next, preferably, a part of the monomer and the persulfate is added, and during the polymerization, the remaining part of the monomer and the persulfate is diluted with a solvent and added continuously. Hydrogen peroxide may be added at the same time as the monomer, but it is preferable to add it all at once or continuously after all the monomers have been added.

In the polymerization, the reaction temperature is preferably from 50 ° C. to a temperature near the boiling point of the solvent in an aqueous solvent.
The polymerization reaction is preferably performed under acidic conditions, and specifically, the pH is preferably less than 5.

After the polymerization reaction, if necessary, neutralization is performed. Examples of the alkaline agent used for neutralization include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, hydroxides of alkaline earth metals such as calcium hydroxide and magnesium hydroxide, ammonia, monoethanolamine and diethanolamine. And organic amines such as triethanolamine, and one or more of them can be used. The pH after neutralization is preferably set to 4 or more, and may be over-neutralized for bacteria prevention or the like.

In the present invention, the oxidizing agent remains in the (co) polymer aqueous solution after the production, and in order to decompose the oxidizing agent, a reducing agent is added by an amount equal to or more than the mole of the remaining oxidizing agent. Is also good. The type of reducing agent is not particularly limited, but is preferably an inorganic reducing agent, sodium sulfite, potassium sulfite, sodium hydrogen sulfite, sulfites such as potassium hydrogen sulfite, sodium thiosulfate, thiosulfates such as potassium thiosulfate, Examples include phosphorous acid (salt) such as phosphorous acid and sodium phosphite, and hypophosphorous acid (salt) such as hypophosphorous acid and sodium hypophosphite. As the salt, sodium,
Examples thereof include alkali metal salts such as potassium, alkaline earth metal salts such as calcium and magnesium, ammonium salts, organic amine salts such as monoethanolamine and triethanolamine, and the like, and alkali metal salts such as sodium and potassium are preferable. One or more of these inorganic reducing agents are used.

The temperature at which the reducing agent is added is preferably room temperature. When the viscosity of the (co) polymer aqueous solution is high, it is possible to increase the temperature and add the reducing agent, but the temperature is preferably 50 ° C. or lower. The addition time is not limited as long as it is not oxidized by an oxidizing agent such as oxygen in the aqueous solution of the (meth) acrylic acid (co) polymer to be added and loses its function as a reducing agent.

In the (meth) acrylic acid (co) polymer obtained in the present invention, the hydroquinone compound, which is a polymerization inhibitor, is decomposed and reduced, and no coloring is observed even in the production of a detergent using the same. Suitable for detergent builders and high quality products can be obtained.

[0030]

EXAMPLES In the examples,% and parts are by weight unless otherwise specified. The hydroquinone compound was quantified by the following method.

<Quantitative Determination of Hydroquinone Compound> The amount of the hydroquinone compound (methquinone) contained in the (meth) acrylic acid (co) polymer was determined by the following chromatography conditions. Column: Tosoh TSK-GEL Super AW2
500 mobile phase: 0.1 mmol / L phosphate buffer (pH 7) / acetonitrile = 70/30 (vol / vol) Detector: UV (220 nm) Column temperature: 40 ° C. Flow rate: 0.6 ml / min Sample: polymer 10 g of a sample solution prepared by dissolving 2 g of an aqueous solution (about 40%) in ion-exchanged water to 20 ml is injected. Methoquinone detection limit: 0.1 mg / kg Example 1 150 g of ion-exchanged water was placed in a 2 L four-neck separable flask.
0.85 g of 0.1% ferrous sulfate heptahydrate (0.01 part per 1 part of methoquinone) was charged and heated in a bath at 105 ° C., followed by 7 g of 2-mercaptoethanol and 300 g of an 80% acrylic acid aqueous solution. (Metoquinone content: 0.048 g) and an aqueous solution of sodium persulfate obtained by dissolving 2.4 g of sodium persulfate (50 parts with respect to 1 part of metoquinone) in 96 g of ion-exchanged water were dropped for 4 hours and 6 hours, respectively. Then, polymerization was performed. Thereafter, 25.02 g of 35% hydrogen peroxide solution (0.
26 mol, persulfate / hydrogen peroxide (molar ratio) = 0.0
40) After throwing in and aging for 3 hours, cool down to 48%
Neutralization was performed with 258.6 g of an aqueous sodium hydroxide solution.
The weight average molecular weight of the sodium polyacrylate thus obtained was 10,000. No residual methoquinone was detected.

Example 2 Sodium polyacrylate was prepared in the same manner as in Example 1 except that 0.6 g of 0.1% cupric sulfate (0.0048 part per 1 part of methoquinone) was added instead of ferrous sulfate. Manufactured. The weight average molecular weight of the sodium polyacrylate thus obtained was 10,000, and no residual methoquinone was detected.

Example 3 72.5 ion-exchanged water was placed in a 300 L glass-lined reaction tank.
kg and ferrous sulfate heptahydrate 0.28 g (0.0075 part per 1 part of methoquinone) were charged, and the temperature was raised to 105 ° C.
2.1 kg of 2-mercaptoethanol, 100 kg of an 80% aqueous solution of acrylic acid (content of methoquinone: 0.016 kg),
And 9% sodium persulfate aqueous solution 8.8 kg (methquinone 1
(49.5 parts per part) was dropped for 5 hours and 6 hours, respectively, to carry out polymerization. Then 11kg of 35% hydrogen peroxide solution
(0.11 kmol, persulfate / hydrogen peroxide (molar ratio)
= 0.029), aged for 3 hours, cooled, and neutralized with 81.1 kg of a 48% aqueous sodium hydroxide solution. The weight average molecular weight of the obtained sodium polyacrylate was 11,000, and no residual methoquinone was detected.

Using the obtained sodium polyacrylate as a builder, a detergent powder was produced according to the method of WO99 / 29830, and a colorless detergent powder was obtained.

Example 4 Deionized water (72.5) was placed in a 300 L glass-lined reaction tank.
KG and 0.28 g of ferrous sulfate heptahydrate (0.0075 part per 1 part of methoquinone), and after heating to 70 ° C., 100 kg of an 80% aqueous solution of acrylic acid (methquinone content: 0.1%). 016 kg), 30% sodium persulfate aqueous solution 8.8
KG (165 parts per 1 part of methoquinone) and 16.5 kg of 35% sodium bisulfite were added dropwise for 6 hours to carry out polymerization. Then 2.4 kg of 35% hydrogen peroxide (24.7m
ol, persulfate / hydrogen peroxide (molar ratio) = 0.45), aged for 3 hours, cooled, and neutralized with 81.1 kg of a 48% aqueous sodium hydroxide solution. The weight average molecular weight of the obtained sodium polyacrylate was 11,000, and no residual methoquinone was detected.

Using the obtained sodium polyacrylate as a builder, a detergent powder was produced by the method of WO99 / 29830, and a detergent powder without coloring was obtained.

Comparative Example 1 A sodium polyacrylate was produced in the same manner as in Example 1 except that ferrous sulfate was not added. The weight average molecular weight of the obtained sodium polyacrylate was 10,000, and the residual methoquinone content was 63 mg / kg.

Comparative Example 2 Sodium polyacrylate was produced in the same manner as in Example 1 except that ferrous sulfate was not added and 0.26 mol of sodium persulfate was added instead of hydrogen peroxide. The weight average molecular weight of the obtained sodium polyacrylate was 10,000, and the residual methoquinone content was 55 mg / kg.

COMPARATIVE EXAMPLE 3 A 2-L four-neck separable flask was charged with 225 g of ion-exchanged water and 6.4 g of 0.1% ferrous sulfate heptahydrate (0.485 part per 1 part of methoquinone), and heated at 70 ° C. Then, 450 g of an 80% aqueous solution of acrylic acid (methoquinone content: 0.072 g) and 3.57 g of sodium persulfate (49.5 parts per 1 part of metoquinone) were dissolved in 90 g of ion-exchanged water. An aqueous solution of sodium persulfite and an aqueous solution of sodium bisulfite in which 26.0 g of sodium hydrogen sulfite were dissolved in 78.3 g of ion-exchanged water were each added dropwise for 4 hours to carry out polymerization. After cooling the reaction mixture, a 48% aqueous sodium hydroxide solution was added to 395.
Neutralization was performed with 5 g. The weight average molecular weight of the sodium polyacrylate thus obtained is 5,000,
The residual methquinone content was 23 mg / kg.

Comparative Example 4 Example 4 except that ferrous sulfate and hydrogen peroxide were not added.
Sodium polyacrylate was produced in the same manner as described above. The weight average molecular weight of the obtained sodium polyacrylate was 11,000, and the residual methoquinone content was 25 mg / kg.

Using the obtained sodium polyacrylate as a builder, a detergent powder was produced according to the method of WO99 / 29830, whereby a detergent powder colored pink was obtained.

[0042]

According to the production method of the present invention, a monomer containing a hydroquinone compound and essentially containing (meth) acrylic acid (salt) is used to reduce the hydroquinone compound content to 10%.
A (meth) acrylic acid (co) polymer reduced to not more than mg / kg can be obtained, and coloring of a detergent using the (meth) acrylic acid (co) polymer can be significantly suppressed. .

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Claims (5)

[Claims] 1. A method for producing a (meth) acrylic acid polymer or copolymer (hereinafter referred to as a (co) polymer) by polymerizing a monomer having acrylic acid or methacrylic acid or a salt thereof as an essential component. , In the reaction system, a hydroquinone compound,
A persulfate, a water-soluble metal salt and hydrogen peroxide are used in an amount of 15 to 300 parts by weight of a persulfate and 0.001 to 0.05 part by weight of a water-soluble metal salt per 1 part by weight of a hydroquinone compound. A method for producing a (meth) acrylic acid (co) polymer in which hydrogen peroxide (molar ratio) is present at a ratio of 0.01 to 0.5. 2. The process for producing a (meth) acrylic acid (co) polymer according to claim 1, wherein the water-soluble metal salt is ferrous sulfate and / or cupric sulfate. 3. The (meth) acrylic acid (co) according to claim 1, wherein the persulfate is at least one selected from sodium persulfate, potassium persulfate and ammonium persulfate.
Polymer production method. 4. The (meth) acrylic acid (co) according to claim 1, wherein the content of the hydroquinone compound in the (meth) acrylic acid (co) polymer is 10 mg / kg or less. Polymer production method. 5. The (meth) acrylic acid (co) according to claim 1, wherein the hydroquinone compound is p-hydroxyphenol or p-methoxyphenol.
Polymer production method.