JPS6346065B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for producing sulfoalkyl (meth)acrylate salts. More specifically, the present invention relates to a method for producing a sulfoalkyl (meth)acrylate salt that is simple, contains a small amount of polymerization inhibitor, and has good storage stability.

(Prior art) Sulfoalkyl (meth)acrylate salt is
Produced by (meth)acrylic acid and hydroxyalkanesulfonate and dehydration esterification reaction,
It is used as a polymer itself or as a copolymer with other vinyl monomers in fields such as scale inhibitors, drilling mud conditioners, and water-absorbing resins. The dehydration esterification reaction shown in the following reaction formula is generally carried out in an inert organic solvent, and dehydration is performed while distilling off the water produced by the esterification reaction in the form of an azeotrope.

(However, in the formula, R ¹ , R ² , R ³ and R ⁴ each independently represent hydrogen, a methyl group, or an ethyl group,
R ⁵ represents hydrogen or a methyl group, and X represents a mono- to trivalent metal, an ammonium group, or a substituted ammonium group. ) Since the raw material hydroxyalkanesulfonate and the product sulfoalkyl (meth)acrylate salt are insoluble in inert organic solvents, the esterification reaction proceeds in a slurry state, and the slurry state remains even after the reaction is completed. . Therefore, in order to obtain a sulfoalkyl (meth)acrylate salt, the conventional method has been to filter it, wash it with a low-boiling organic solvent, and then dry it.

(Problems to be Solved by the Invention) However, the powdered sulfoalkyl (meth)acrylate salt obtained by this conventional method is easily oxidized in the air and easily generates peroxides. When used after being dissolved in a monomer, it has the disadvantage that it polymerizes immediately after dissolution. In addition, in the conventional method, the polymerization inhibitor used during the esterification reaction cannot be sufficiently removed by the washing step alone, so a large amount of the polymerization inhibitor remains in the obtained sulfoalkyl (meth)acrylate salt, causing polymerization. It had the disadvantage of having an adverse effect when used. Furthermore, in the conventional method, it is necessary to use a large amount of a low-boiling point organic solvent to wash the filter material, which requires a recovery process for the organic solvent and a drying step for the filter material, resulting in safety concerns. It was also not a satisfactory method from an economic point of view.

Such situations and sulfoalkyl (meth)
Considering the fact that when acrylate salts are used in polymerization etc., they are used exclusively as aqueous solutions, the present inventors were able to produce sulfoalkyl (meth)acrylate salts with simple operations, and the storage stability of the product As a result of extensive research into manufacturing methods that would improve polymerization, the present invention was completed.

(Means and effects for solving the problems) The present invention is based on the general formula (However, in the formula, R ¹ , R ² , R ³ and R ⁴ each independently represent hydrogen, a methyl group or an ethyl group, and
represents a mono- to trivalent metal, an ammonium group, or a substituted ammonium group. ) Hydroxyalkanesulfonate (A) represented by
After performing the esterification reaction between (meth)acrylic acid and (meth)acrylic acid in a water-insoluble inert organic solvent while distilling off the water produced in the esterification reaction as an azeotrope with the organic solvent, Adding water and, if necessary, a basic substance to the organic solvent slurry of the obtained reaction product to dissolve the reaction product in the aqueous phase,
General formula characterized by separation of aqueous phase from organic solvent phase (However, in the formula, R ¹ , R ² , R ³ , R ⁴ and X are as described above, and R ⁵ represents hydrogen or a methyl group.) It is something.

The hydroxyalkanesulfonic acid salt (A) used as a raw material in the present invention is represented by the above general formula, and includes, for example, 2-hydroxyethanesulfonic acid (isethionic acid), 2-hydroxypropane-1-sulfonic acid, 1 -Hydroxypropane-2-sulfonic acid, 2-hydroxybutane-1-
Mono- to trivalent metal salts such as sodium salts, potassium salts, calcium salts, and aluminum salts of hydroxyalkanesulfonic acids such as sulfonic acid, 1-hydroxybutane-2-sulfonic acid, and 3-hydroxybutane-2-sulfonic acid; methylammonium salt,
Examples include substituted ammonium salts or ammonium salts such as dimethylammonium salt, ethylammonium salt, diethylammonium salt, and triethylammonium salt.

In the present invention, (meth)acrylic acid refers to acrylic acid or methacrylic acid.

The sulfoalkyl (meth)acrylate salt obtained in the present invention is represented by the above general formula, for example, 2-sulfoethyl acrylate, 2-
Sulfoethyl methacrylate, 1-sulfopropan-2-yl acrylate, 1-sulfopropan-2-yl methacrylate, 2-sulfopropyl acrylate, 2-sulfopropyl methacrylate, 1-sulfobutan-2-yl acrylate,
1-sulfobutan-2-yl methacrylate, 2
- Sodium salts, potassium salts, calcium salts of sulfoalkyl (meth)acrylates such as sulfobutyl acrylate, 2-sulfobutyl methacrylate, 3-sulfobutan-2-yl acrylate, and 3-sulfobutan-2-yl methacrylate;
Mono- to trivalent metal salts such as aluminum salts; substituted ammonium salts or ammonium salts such as methylammonium salts, dimethylammonium salts, ethylammonium salts, diethylammonium salts, and triethylammonium salts.

In the present invention, first, an esterification reaction between (meth)acrylic acid and a hydroxyalkanesulfonate (A) is carried out, preferably in the presence of an esterification reaction catalyst,
The esterification reaction is carried out in a water-insoluble inert organic solvent while water produced during the esterification reaction is distilled off as an azeotrope with the organic solvent.

In the present invention, the quantitative ratio when reacting (meth)acrylic acid and hydroxyalkanesulfonate (A) affects the reaction rate, yield, and purity, so the optimal quantitative ratio should be selected as appropriate to carry out the reaction. Good. Generally, it is preferable to use 1.2 to 3.0 times the number of moles of (meth)acrylic acid as the hydroxyalkanesulfonate (A). If the amount is less than 1.2 times, the reaction rate will be slow, and even if an excess amount of more than 3.0 times is used, the reaction rate will not be increased very much.

The water-insoluble inert organic solvent used in the present invention is insoluble in water and facilitates subsequent separation operations, forms an azeotrope with water to facilitate dehydration operations, and is effective against raw materials and reaction products. Any organic solvent can be used as long as it is inert, but since the dehydration and esterification reaction is carried out at the boiling point of the organic solvent, those having a boiling point of 70 to 160°C are preferred. If the boiling point is less than 70°C, the reaction rate will be low, and if the boiling point exceeds 160°C, side reactions such as polymerization of raw materials or reaction products will increase. Examples of such water-insoluble inert organic solvents include benzene, cyclohexane, toluene, xylene,
Examples include ethylbenzene and monochlorobenzene. The amount of the organic solvent used is preferably 1 to 4 times the weight of the hydroxyalkanesulfonate (A). The amount of organic solvent used is 1
If the amount is less than twice the amount, stirring during the reaction will be difficult, and if the amount exceeds 4 times the amount, the reaction rate will be slow.

In order to prevent the raw material (meth)acrylic acid and the generated sulfoalkyl (meth)acrylate salt from polymerizing during the esterification reaction, it is common to use a known polymerization inhibitor. The amount is preferably 100 to 10,000 ppm based on the total amount of the raw material mixture before reaction. Examples of the polymerization inhibitor used include hydroquinone,
Hydroquinone monomethyl ether, 2,6-di-
Examples include t-butyl-4-methylphenol, 2,4-dimethyl-6-t-butylphenol, and phenothiazine.

Furthermore, in the present invention, during the esterification reaction,
Air or oxygen may be blown into the system to prevent polymerization.

Examples of the esterification reaction catalyst suitably used in the present invention include sulfuric acid and organic sulfonic acids such as benzenesulfonic acid, para-toluenesulfonic acid, methanesulfonic acid, laurylsulfonic acid, and isethionic acid. The amount of the catalyst added is usually preferably 3 to 30 mol% of the hydroxyalkanesulfonate, which is the raw material alcohol. If it is less than 3 mol%, the reaction rate will be low,
On the other hand, even if an excess amount exceeding 30 mol % is used, the reaction rate does not increase much.

In the present invention, after carrying out the esterification reaction as described above, water and, if necessary, a basic substance are added to a water-insoluble inert organic solvent slurry of the obtained reaction product. The sulfoalkyl (meth)acrylate salt obtained is dissolved in the aqueous phase and the aqueous phase is separated from the organic solvent phase. The amount of water added is preferably 0.6 to 6 times the weight of the raw material hydroxyalkanesulfonate (A). If the amount of water is less than 0.6 times, it will be difficult to sufficiently dissolve the generated sulfoalkyl (meth)acrylate salt in the water phase to form a uniform aqueous solution, and the polymerization inhibitor used during the esterification reaction will be The amount mixed into the aqueous phase increases. On the other hand, if it exceeds 6 times, the concentration of the sulfoalkyl (meth)acrylate salt in the aqueous phase becomes too low, making it difficult to use it in an aqueous solution state during polymerization.

In the present invention, when adding water, it is preferable to simultaneously add a basic substance to neutralize the strongly acidic esterification reaction catalyst. The amount of the basic substance used is preferably adjusted so that the pH of the aqueous phase to be produced is 3 to 7. If the pH is less than 3 or more than 7, hydrolysis of the sulfoalkyl (meth)acrylate salt may occur when the aqueous phase is stored as an aqueous product solution or dried to form a powdered product, resulting in poor storage stability. The properties of the powder may deteriorate, or a highly pure powder product may not be obtained.

Basic substances used for neutralization include, for example, mono- to trivalent metal hydroxides such as sodium hydroxide, potassium hydroxide, calcium hydroxide, and aluminum hydroxide; methylamine, dimethylamine, ethylamine, diethylamine, and triethylamine. and ammonia, and may be used in the form of an aqueous solution thereof.

The temperature at which water or water and a basic substance are added to the water-insoluble inert organic solvent slurry of the esterification reaction product is preferably 80°C or lower. 80℃
If the temperature exceeds 100%, hydrolysis may occur during addition, resulting in a low product yield.

In the present invention, the aqueous phase separated from the organic solvent phase can be effectively applied as it is as an aqueous sulfoalkyl (meth)acrylate salt solution to polymerization applications such as the preparation of (co)polymers. Furthermore, if it is necessary to obtain a powder product, the aqueous solution can be dried to obtain a powder product. but,
When sulfoalkyl (meth)acrylate salts are used for polymerization purposes, they are usually dissolved in water before being subjected to polymerization, and it goes without saying that it is advantageous to preserve them in the form of an aqueous solution.

(Effects of the Invention) According to the production method of the present invention, the sulfoalkyl (meth)acrylate salt can be obtained in the form of an aqueous solution, so there is no concern about peroxide formation, and it has good storage stability and can be stored for a long period of time. It will not polymerize even if it is left in place. In addition, the polymerization inhibitor used during the esterification reaction is largely distributed in the water-insoluble inert organic solvent phase, and only a small amount is mixed into the aqueous solution of the product, so it may not have an adverse effect when applied to polymerization applications. do not have. Another advantage is that it does not require complicated and dangerous steps such as filtration of organic solvents, washing, and drying, unlike conventional methods.

(Examples) Next, the present invention will be explained in more detail with reference to Examples, but the scope of the present invention is not limited by these Examples. Note that % in the examples indicates weight % unless otherwise specified.

Example 1 In one flask equipped with a reflux condenser with stirrer, thermometer and water separator, 172 g (2 moles) of methacrylic acid, 148 g of sodium isethionate
g (1 mol), para-toluenesulfonic acid 17.2g
(0.1 mol), 0.52 g of phenothiazine, and 400 g of xylene were charged, and heated from the outside in an oil bath while stirring to raise the internal temperature to 139°C.
Water produced by the reaction was distilled out as an azeotrope with xylene, and water was observed to separate in the water separator. 7 hours after the start of distillation,
Distilled water became 18 ml and water distillation stopped, so
The reaction was completed and the mixture was cooled to 40°C. Next, a solution prepared by dissolving 6 g of sodium hydroxide in 300 g of water was added to the resulting xylene slurry of the reaction product.
Stir vigorously for a minute. Thereafter, stirring was stopped, and the mixture was immediately separated into an upper xylene phase and a lower aqueous phase. The aqueous phase was extracted from the bottom of the container to obtain an aqueous solution of the reaction product. The yield of aqueous solution was 534 g. In addition, when the components in the aqueous solution were analyzed by capillary isotachophoresis analysis and acid/base titration, 2-
Sulfoethyl methacrylate sodium salt 39.6
%, methacrylic acid 1.95%, and sodium methacrylate 1.01%, and when analyzed by color method using bromine, the phenothiazine content was 76 ppm. Therefore, the yield of 2-sulfoethyl methacrylate sodium salt was 97.8%.

Even after storing the obtained aqueous solution at 25℃ for 1 year,
There was no change in the composition in the aqueous solution. Furthermore, when 0.1% ammonium persulfate (based on monomer) and 0.01% L-ascorbic acid (based on monomer) were added to the aqueous solution after storage for one year, polymerization was performed at 40°C, and the polymerization rate was 99.2%.

Example 2 In the same reaction vessel as in Example 1, 144 g of acrylic acid was added.
(2 mol), ammonium 2-hydroxypropane-1-sulfonate 157 g (1 mol), sulfuric acid 9.8 g
(0.1 mol), 0.37 g of phenothiazine and 400 g of cyclohexane were added, and the internal temperature was brought to 80°C while stirring.
The temperature was raised to 0.degree. C., and the esterification reaction was carried out in the same manner as in Example 1. After 10 hours had passed since the start of distillation of water, the amount of distilled water was 18 ml and the distillation of water had stopped, so the reaction was terminated and the mixture was cooled to 40°C. Then, to the cyclohexane slurry of the obtained reaction product,
A solution prepared by dissolving 12.1 g of 28% aqueous ammonia in 270 g of water was added and stirred vigorously for 10 minutes. Thereafter, stirring was stopped, and the mixture was immediately separated into an upper cyclohexane phase and a lower aqueous phase. The aqueous phase was extracted from the bottom of the container to obtain an aqueous solution of the reaction product. The yield of aqueous solution was 512 g. In addition, the components in the aqueous solution are 1-
The contents were 38.6% sulfopropan-2-yl acrylate ammonium salt, 4.22% acrylic acid, 1.73% sodium acrylate, and 82 ppm of phenothiazine. Therefore, the yield of 1-sulfopropan-2-yl acrylate ammonium salt was 93.6%.

Even after storing the obtained aqueous solution at 25℃ for 1 year,
There was no change in the composition in the aqueous solution. Furthermore, when 0.1% ammonium persulfate (based on monomer) and 0.01% L-ascorbic acid (based on monomer) were added to the aqueous solution after storage for one year, polymerization was performed at 40°C, and the polymerization rate was 99.1%.

Example 3 The esterification reaction was carried out in the same manner as in Example 1. After the reaction was completed, the mixture was cooled to 40° C., and then 300 g of water was added to the resulting xylene slurry of the reaction product, and the mixture was vigorously stirred for 10 minutes. Thereafter, stirring was stopped, and the mixture was immediately separated into an upper xylene phase and a lower aqueous phase. Pull out the aqueous phase from the bottom of the container,
An aqueous solution of the reaction product was obtained. The yield of the aqueous solution is 526
It was hot at g. In addition, the components in the aqueous solution are 2-sulfoethyl methacrylate sodium salt 38.0%,
It contained 2.66% methacrylic acid and 80 ppm phenothiazine. Therefore, the yield of 2-sulfoethyl methacrylate sodium salt was 92.5%.

Comparative Example 1 The esterification reaction was carried out in the same manner as in Example 1. After the esterification reaction was completed, the resulting xylene slurry of the reaction product was filtered under suction. Thereafter, it was washed twice with 200 ml of acetone and dried under reduced pressure to obtain a powder of 2-sulfoethyl methacrylate sodium salt. The yield was 232g. Purity is 90.1%, methacrylic acid as impurity
It contained 2.6% and 1240ppm of phenothiazine.

After storing the obtained powder at 25°C for one month, an attempt was made to dissolve it in water and subject it to polymerization, but polymerization started just by dissolving it in water, and the polymerization rate could only rise to 64.5%.

As described above, the production method of the present invention is a simpler and safer method than the method of the comparative example, and the sulfoalkyl (meth)acrylate salt obtained by the production method of the present invention is The amount of polymerization inhibitor mixed in is smaller than that obtained with
It can also be seen that the storage stability is good.

Claims (1)

[Claims] 1. General formula (However, in the formula, R ¹ , R ² , R ³ and R ⁴ each independently represent hydrogen, a methyl group or an ethyl group, and
represents a mono- to trivalent metal, an ammonium group, or a substituted ammonium group. ) Hydroxyalkanesulfonate (A) represented by
After performing the esterification reaction between (meth)acrylic acid and (meth)acrylic acid in a water-insoluble inert organic solvent while distilling off the water produced in the esterification reaction as an azeotrope with the organic solvent, Adding water and, if necessary, a basic substance to the organic solvent slurry of the obtained reaction product to dissolve the reaction product in the aqueous phase,
General formula characterized by separation of aqueous phase from organic solvent phase (However, in the formula, R ¹ , R ² , R ³ , R ⁴ and X are as described above, and R ⁵ represents hydrogen or a methyl group.) A method for producing a sulfoalkyl (meth)acrylate salt represented by the following.