JPH04124164A - Production of aqueous solution of unsaturated quaternary ammonium salt - Google Patents

Abstract

PURPOSE:To obtain the subject aqueous solution having high quality in high yield by supplying methyl chloride to a region separated into two layers and formed by combining a (meth)acrylate used as a raw material, water and an unsaturated quaternary ammonium salt at specific ratios. CONSTITUTION:An aqueous solution of an unsaturated quaternary ammonium salt is produced by reacting dimethylaminoethyl acrylate or dimethylaminoethyl methacrylate with methyl chloride. In the above process, the reaction is carried out by supplying methyl chloride to a region enclosed with lines connecting the points (75, 25, 5), (85, 10, 5), (20, 15, 65) and (20, 20, 60) in the triangular diagram of the charging compositions (pts.wt.) of the (meth)acryiate (DAA), water and quaternary ammonium salt (DAC).

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing an unsaturated quaternary ammonium salt, more specifically, a method for producing an unsaturated quaternary ammonium salt, and more specifically, a method for producing a quaternary methyl chloride of dimethylamine ethyl acrylate or dimethylaminoethyl methacrylate. The present invention relates to an industrially advantageous method for producing an aqueous solution of a grade ammonium salt with high purity.

Unsaturated quaternary ammonium salts are raw materials for cationic polymers, and are industrially useful substances used in a wide range of fields such as polymer flocculants, paper strength agents, and antistatic agents. Among these, methyl chloride quaternary ammonium salts of dimethylaminoethyl acrylate or dimethylaminoethyl methacrylate are widely used as cationic monomers used as raw materials for polymer flocculants.

(Prior art and problems) As a cationic monomer that is a raw material for a cationic polymer, a vinyl monomer having a tertiary amino group can be used with an acid such as hydrochloric acid or sulfuric acid, or with an acid such as methyl chloride, dimethyl sulfuric acid,
An unsaturated quaternary ammonium salt obtained by treatment with a quaternizing agent such as benzyl chloride is used. The cationic monomer is polymerized alone or copolymerized with acrylamide or the like to produce a cationic polymer flocculant for use.

Since this polymerization reaction is carried out in the form of an aqueous solution, the unsaturated quaternary ammonium salt is generally obtained in the form of an aqueous solution.

Unsaturated quaternary ammonium salts are synthesized by a quaternization reaction called the Menschudkin reaction, but it is an exothermic reaction, and as the temperature increases, thermal polymerization of unsaturated quaternary ammonium salts tends to occur. The fact that the quaternary ammonium salt itself is solid and difficult to handle poses problems in industrial processes.

Therefore, when synthesizing methyl chloride quaternary ammonium salt of dimethylaminoethyl acrylate or dimethylaminoethyl methacrylate for boat fishing, gradually add methyl chloride as a quaternizing agent in the presence of an organic compound or water as a solvent. A method is adopted in which the reaction is carried out while supplying the reaction heat and removing the reaction heat.

When water is used as a solvent in the second reaction, it is possible to obtain a highly concentrated aqueous solution without precipitating the unsaturated quaternary ammonium salt due to its high solubility; however, on the other hand, dimethylaminoethyl acrylate or dimethyl There is a problem in that aminoethyl methacrylate is easily hydrolyzed, and impurities resulting from the hydrolyzate deteriorate the quality and yield of the desired unsaturated quaternary ammonium salt. In particular, a decrease in product purity is disadvantageous in that it causes a decrease in the degree of polymerization when used as a raw material for a cationic polymer, which is the final use. Therefore, when quaternizing a vinyl monomer having a tertiary amino group in an aqueous solvent, it is important to suppress hydrolysis as much as possible, and various methods have been proposed for this purpose.

For example, JP-A-51-76216 discloses that the reaction is carried out at a temperature of 50°C or lower, particularly 10 to 30°C. JP-A-52-3'1O16 and JP-A-52-31
No. 017 discloses that an unsaturated quaternary ammonium salt should be present in advance, that the initial concentration of the raw materials should be 80% or more, and that it is preferable to carry out the reaction at a temperature of 25 to 40°C. Also, JP-A-57-126
452 discloses that water is supplied intermittently or continuously in parallel with the addition of a quaternizing agent, and that the reaction can be carried out at a relatively low temperature of 20 to 40 °C to suppress hydrolysis. Recommended.

In these quaternization methods, when the temperature is low, the hydrolysis rate of the raw material can be reduced to some extent, but at the same time, the rate of the target quaternization reaction is also reduced, and the formation of unsaturated quaternary ammonium salts is reduced. There is a problem that the space-time yield is significantly reduced. In addition, if the initial concentration of the raw materials is high, the reaction occurs in a supersaturated state, which tends to cause the precipitation of unsaturated quaternary ammonium salts and the formation of scale, making it difficult to increase the stirring load of the reaction solution and control the reaction temperature. The problem is that it is difficult.

In addition, in JP-A-55-127351, the pH of the reaction solution is
It is proposed that the reaction be carried out while maintaining the pH at 6 to 9. As a specific method, a quaternizing agent is placed in advance, and the raw vinyl monomer and water are mixed to a pH of 6 to 9. A method is disclosed for supplying the water so as to maintain it.

However, when the quaternizing agent is methyl chloride, a higher pressure reactor is required, making the method industrially disadvantageous. Furthermore, in JP-A No. 61-50947, when dimethylaminoethyl acrylate is used as a raw material, in order to suppress the by-product of acrylic acid, a mixture of water and an abrotic low-boiling organic solvent that is compatible with water is used. A method is proposed in which an alkyl (meth)acrylate and methyl chloride are reacted while being supplied intermittently or continuously. However, when organic solvents are used together, it is essential to separate and recover the solvent, and in order to reuse the solvent, a solvent purification process is required, which complicates the process industrially and reduces energy costs. It is also a disadvantageous method.

Although the methods proposed so far can suppress hydrolysis to some extent for methacrylates, which are relatively difficult to hydrolyze, they are insufficiently effective in suppressing hydrolysis for acrylates, which are more easily hydrolyzed. It's full of things.

As mentioned above, when quaternizing dimethylamine ethyl acrylate or dimethylaminoethyl methacrylate with methyl chloride, an efficient production method that minimizes hydrolysis of the raw material and is also industrially satisfactory has yet to be developed. The current situation is that this has not been done.

Means for Solving Problems〉 In view of the various shortcomings of the conventional methods as described above, the present invention solves the following problems:
The present invention provides a method for obtaining a highly pure and industrially advantageous aqueous solution of methyl chloride quaternary ammonium salt of dimethylamine ethyl acrylate or dimethylaminoethyl methacrylate.

The present inventors used dimethylaminoethyl acrylate as a raw material, which is more easily hydrolyzed than dimethylaminoethyl methacrylate, and investigated the quaternization reaction with methyl chloride in the presence of water. The degree of oxidation increases, the reaction rate decreases, which is undesirable, but the reaction must be carried out at a temperature of 30 tE, and even in reactions at such low temperatures, hydrolysis is not sufficiently suppressed. There was found.

As a result of various studies on ways to suppress hydrolysis, we found that when raw material acrylate or methacrylate, water, and the unsaturated quaternary ammonium salt are mixed at a certain ratio, there is a region where they separate into two layers. We have completed the present invention by discovering that hydrolysis can be suppressed when a quaternization reaction using methyl chloride is carried out on a specific region within the region.

That is, in the present invention, when producing a methyl chloride quaternary ammonium salt of the acrylate or methacrylate by reacting the raw material dimethylaminoethyl acrylate or dimethylaminoethyl methacrylate with methyl chloride, the raw material acrylate or methacrylate, water, and By preparing the three components of the unsaturated quaternary ammonium salt at a composition ratio that causes two-layer separation and reacting with methyl chloride in this state, hydrolysis of the acrylate or methacrylate as a raw material can be suppressed, The present invention provides a method for obtaining the unsaturated quaternary ammonium salt with high yield and high quality.

The method of the present invention will be further explained below.

The combined composition of the raw material acrylate or methacrylate, water, and the quaternary ammonium salt forming the two-layer separation region during charging according to the method of the present invention is the region shown in FIG.

In this region, the liquid is separated into two layers, the upper layer being the raw material acrylate or methacrylate and the lower layer being an aqueous solution of the quaternary ammonium salt.

Outside this range, for example, if the proportion of the quaternary ammonium salt is relatively large, the crystals will not dissolve, and the quaternary ammonium salt produced during the quaternization reaction will also precipitate as crystals, resulting in an increase in stirring load. This is not preferable because it increases the temperature and makes it difficult to remove heat. Moreover, if the proportion of water is relatively large, the liquid will not be separated into two layers but will form a uniform layer, which will result in a significantly high hydrolysis rate in the quaternization reaction, which is not preferable.

Further, the method of the present invention will be explained in detail.

In the two-layer separation region resulting from the above three-component combination, a state is formed in which an interface exists between the raw material acrylate or methacrylate and the quaternary ammonium salt aqueous solution. That is,
Water is in contact with the raw material acrylate or methacrylate at its interface in the form of an aqueous solution of the quaternary ammonium salt. Therefore, unlike the region where the raw material and water are a homogeneous layer, the water is in a restricted state relative to the raw material acrylate or methacrylate. When methyl chloride is supplied in this state and the quaternization reaction is carried out, the hydrolysis rate of the raw material is naturally suppressed, and the generated quaternary ammonium salt automatically moves to the lower layer as an aqueous solution, A high quality aqueous solution of the quaternary ammonium salt can be obtained while suppressing decomposition as much as possible.

In the two-layer separation region for suitably carrying out the method of the present invention, the charging ratios (parts by weight) of the raw materials dimethylamine ethyl acrylate or dimethylaminoethyl methacrylate, water, and the unsaturated quaternary ammonium salt are as follows: Each(
75, 25, and 5), (85, 10, and 5), (2
This is a specific two-layer separation region shown in Figure 1 surrounded by By carrying out the reaction, a high quality aqueous solution of the unsaturated quaternary ammonium salt with suppressed hydrolysis can be obtained with a high yield.

The unsaturated quaternary ammonium salt initially used to form the two-layer separation region in the method of the present invention is preferably a high quality product synthesized separately. After that, a solution dissolved in water can be used. Thereafter, a portion of the quaternary ammonium salt aqueous solution of the product synthesized by the method of the present invention can be left in the reaction system for use.

In the method of the present invention, the quaternizing agent methyl chloride may be supplied to the reaction system for two-layer separation in either gaseous or liquid form, and it may be preferably introduced into the upper or lower layer of the two-layer separation. give. The amount of methyl chloride to be supplied is preferably equal to or more than the same mole, preferably 1.01 to 1.05 times the mole of the raw material acrylate or methacrylate.

Further, by adding an appropriate amount of water only once during the reaction as necessary, precipitation of the unsaturated quaternary ammonium salt can be prevented.

The reaction temperature applied to the method of the present invention is 35-55°C,
Particularly preferred is a temperature range of 40 to 50°C.

In the method of the present invention, it is preferable to use a polymerization inhibitor in order to carry out the reaction at a relatively high temperature, and it is preferable to use p-methoxyphenol or the like. The amount is 1
The range of 000 to 4000 ppm is preferred.

After carrying out the quaternization reaction in the method of the present invention as described above, the reaction product liquid is bubbled with air or the like to remove slightly excess methyl chloride, thereby producing high quality acrylate or methacrylate. An aqueous solution of methyl chloride quaternary ammonium salt can be efficiently obtained. Furthermore, the concentration of the aqueous product solution can be adjusted by removing or adding water in a conventional manner depending on the intended use.

(Examples) The method of the present invention will be further explained below using Examples and Comparative Examples, but the present invention is not limited to these Examples.

Note that when dimethylaminoethyl acrylate is hydrolyzed, it becomes dimethylaminoethanol and acrylic acid, some of which forms salts of dimethylaminoethanol and acrylic acid, and some of which are quaternized with methyl chloride to form quaternary Forms ammonium salts.

After the quaternization reaction was completed, the hydrolysis rate of dimethylaminoethyl acrylate was evaluated by the following method.

Analyze the reaction product liquid by liquid chromatography, quantify by-product free dimethylaminoethanol, salt of dimethylaminoethanol and acrylic acid, quaternary salt of dimethylaminoethanol and methyl chloride, etc., and calculate the hydrolysis rate. did.

Example 1 In a glass autoclave with an internal volume of 11 equipped with a stirrer,
143.5 g (1 mol) of dimethylaminoethyl acrylate with a purity of 99.7 Wt% containing 2000 ppm of polymerization inhibitor p-methoxyphenol and 350 g of acetone were charged, the container was sealed and heated to 40°C.

Next, 53 g (1.05 mol) of methyl chloride was fed at a constant rate over 4 hours while stirring. The reaction temperature is 40-4
The temperature was controlled at 5°C. After aging the reaction product solution for 2 hours, the autoclave was opened and unreacted methyl chloride was purged.

The resulting slurry was suction filtered and dried under reduced pressure to obtain 163.9 g (0,864 mol) of crystals of methyl chloride quaternary ammonium salt of dimethylamine ethyl acrylate.

48g of 39wt% aqueous solution obtained by dissolving these crystals in water
and 48g of water 1 polymerization inhibitor p-methoxyphenol 200g
Dimethylaminoethyl acrylate (containing 0 ppm)2
87.8 g (2 moles) and 0.488 g of p-methoxyphenol, a polymerization inhibitor, were placed in a similar glass autoclave, which was then sealed and heated to 45°C.

The composition of each component at this time was at point A shown in FIG. 1, and the liquid was in a state of being separated into two layers.

Next, 104 g (2.06 mol) of methyl chloride was fed at a constant rate over 5 hours while stirring. Three hours after the start of methyl chloride supply, 48.8 g of water was added.

During this time, the reaction temperature was controlled at 42-46°C. After aging the reaction product solution for 3 hours, excess methyl chloride was removed by aeration, and an aqueous solution of methyl chloride quaternary ammonium salt of dimethylamine ethyl acrylate was added for 5 hours.
28.7 g was obtained. This product aqueous solution has a concentration of 79.7
wt%, and the hydrolysis rate of the acrylate could be kept as low as 1 mol%.

Example 2 In a reactor similar to Example 1, 215.4 g (1.5 mol) of the same dimethylaminoethyl acrylate and 38.8 g of water, 79.7 W t% obtained in Example 1 were added. The acrylate quaternary ammonium salt aqueous solution 198.6
g and polymerization inhibitor p-methoxyphenol 0.657
g, and the mixture was sealed and heated to 43°C. The composition of each component at this time was at point B in Figure 1, and the liquid was in a state of being separated into two layers.

Next, under stirring, 78.3 g of methyl chloride (1,55
mol) was fed at a constant rate over 3 hours. The reaction temperature is 43
The temperature was controlled at ~47°C. After aging the reaction product solution for 3 hours, add 3 hours of water.
After adding 2.5 g, excess methyl chloride was removed by aeration to obtain 556 g of a methyl chloride quaternary ammonium salt aqueous solution of dimethylaminoethyl acrylate. This product aqueous solution has a concentration of 3 Qwt%
The hydrolysis rate was 1.1 mol%.

Comparative Example 1 In the same reactor as in Example 1, 287.4 g (2 mol) of the same dimethylamine ethyl acrylate and 96.3 g of water were added.
, 0.879 g of p-methoxyphenol, a polymerization inhibitor, was charged, the container was sealed and heated to 45°C. The composition of each component at this time was point C in Figure 1, and the liquid was not separated into two layers but was a uniform layer.

Next, under stirring, methyl chloride 104. ．． 2 g (
2.06 mol) was fed at a constant rate over about 5 hours. The reaction temperature was controlled at 43-46°C. After aging the reaction product solution for 3 hours, excess methyl chloride was removed by aeration to obtain 463.8 g of a methyl chloride quaternary ammonium salt aqueous solution of dimethylaminoethyl acrylate. This product aqueous solution has a concentration of 47.7 wt%,
The hydrolysis rate significantly deteriorated to 17.0 mol%. Compared to Examples 1 and 2, the yield was significantly lower and the hydrolysis rate was significantly increased, making the product unsuitable in terms of quality.

Comparative Example 2 In the same reactor as in Example 1, 289.5 g (2.02 mol) of the same dimethylaminoethyl acrylate,
95.3 g of water, 150.6 g of the 79.7 wt% aqueous solution of the acrylate quaternary ammonium salt obtained in Example 1;
g and polymerization inhibitor p-methoxyphenol 0.92 g
was charged, sealed and heated at 42°C. At this time, the composition of each component was at the first target point, and the liquid was in a state where it was separated into two layers.

Next, while stirring, 104.5 g (2,07 g) of methyl chloride
mol) was fed at a constant rate over 4.8 hours. The reaction temperature was controlled at 40-43°C. After aging the reaction product solution for 3 hours,
Excess methyl chloride was removed by aeration to obtain 613.4 g of a methyl chloride quaternary ammonium salt aqueous solution of dimethylaminoethyl acrylate.

This product aqueous solution had a concentration of 58.7 Wt% and a hydrolysis rate of 13.8 mol%.

Compared to Examples 1 and 2, the yield and hydrolysis rate tended to be worse.

Comparative Example 3 In the same reactor as in Example 1, 143.6 g (1 mol) of the same dimethylaminoethyl acrylate and 321 g of water,
8 g, 107.8 g of the acrylate quaternary ammonium salt aqueous solution of 79.7 Wt% obtained in Example 1, and 1.259 g of p-methoxyphenol as a polymerization inhibitor, and the mixture was sealed and heated to 45°C. . The composition of each component at this time was at point E in Figure 1, and the liquid was not separated into two layers but was a uniform layer.

Next, 52 g (1.03 mol) of methyl chloride was fed at a constant rate over 5 hours while stirring. The reaction temperature is 43-4
The temperature was controlled at 6°C. After aging the reaction product solution for 3 hours, excess methyl chloride was removed by aeration to obtain 604.6 g of an aqueous solution of methyl chloride quaternary ammonium salt of dimethylaminoethyl acrylate. This product aqueous solution has a concentration of 38.2 W t% and a hydrolysis rate of 2
It significantly deteriorated to 5.1 mol%.

Compared to Examples 1 and 2, the yield was significantly lower and the hydrolysis rate was significantly increased, making the product unsuitable in terms of quality.

(Effects of the Invention) The method of the present invention involves reacting dimethylaminoethyl acrylate or dimethylaminoethyl methacrylate with methyl chloride to produce a methyl chloride quaternary ammonium salt aqueous solution of the acrylate or methacrylate. By reacting methyl chloride with a state of two-layer separation formed at a specific ratio of methacrylate, water, and the unsaturated quaternary ammonium salt, hydrolysis is suppressed and a high yield is obtained. This is a method for producing a high quality unsaturated quaternary ammonium salt aqueous solution and has great industrial significance.

[Brief explanation of the drawing]

FIG. 1 shows a two-layer separation region consisting of three components: raw material dimethylaminoethyl acrylate, water, and the quaternary ammonium salt, and an implementation region of the present invention. Points A and B in the figure indicate Examples 1 and 2, and points C1D and E indicate Comparative Examples 1.2 and 3. (The unit of each component composition is parts by weight). Procedural amendment band (method) December 4, 1990

Claims (1)

[Claims] When supplying methyl chloride to dimethylaminoethyl acrylate or dimethylaminoethyl methacrylate and reacting it to produce a methyl chloride quaternary ammonium salt aqueous solution of the acrylate or methacrylate, the raw material acrylate or methacrylate, water,
and the unsaturated quaternary ammonium salt are combined to form a two-layer separated state, and the charging composition (parts by weight) of the acrylate or methacrylate, water, and the unsaturated quaternary ammonium salt is , respectively (75, 25
, and 5), (85, 10, and 5), (20, 15,
and 65), a method for producing the unsaturated quaternary ammonium salt aqueous solution, which comprises reacting methyl chloride in the two-layer separation region surrounded by (20, 20, and 60).