JPH10237248A - Aqueous polystyrenesulfonate solution and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aqueous polystyrenesulfonate solution having chloride and sulfate ions content in a specified range and a specific color by polymerizing a monomer in the presence of a polymerization initiator comprising a water-soluble salt of azobiscyanocarboxylic acid and/or 2,2'-azobis 2-methyl-N-[1,1'-bis(hydroxymethyl]-2-hydroxyethyl}propionamide}. SOLUTION: An aqueous solution of the product has a content of chloride and sulfate ions of 1-100ppm and a color (APHA) of 10-60 as measured on a 20wt.% aqueous solution. The polymerization initiator being a water-soluble salt of azobiscyanocarboxylic acid is a compound of the formula (wherein M is Li, Na, K or NH4 ). It is desirable that the production method is a consecutive addition one comprising polymerizing a styrene sulfonate monomer while adding dropwise an aqueous solution of the monomer and a polymerization initiator to a polymerizer, and that the concentration of the polymerization solution is 5-30wt.% in consideration for the production efficiency and the viscosity of the polymer. This solution can be used in the fields of semiconductors, photography, etc., by virtue of the lowered content of contaminant ions and the improved color.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polystyrene sulfonate aqueous solution and a method for producing the same. More specifically, to provide an aqueous solution of polystyrene sulfonate in which both a chlorine ion and a sulfate ion are 100 ppm or less and a hue (APHA) is 60 or less in a 20% by weight aqueous solution of polystyrene sulfonate to obtain an aqueous solution of polystyrene sulfonate. Chloride ion by polymerizing a styrene sulfonate monomer using a specific initiator to
The present invention relates to a method for producing a polystyrene sulfonate aqueous solution in which sulfate ions are significantly reduced and the hue is improved.

[0002]

2. Description of the Related Art Hitherto, ionic impurities such as chloride ions and sulfate ions have been mixed into an aqueous solution of polystyrene sulfonate, and furthermore, there have been disadvantages such as inferior hue. As a route for mixing these impurities, when polymerizing chloride, bromide, sulfide and styrene sulfonate monomer by-produced in producing styrene sulfonate monomer which is a raw material of polystyrene sulfonate. The initiator used and the like can be considered. Improvements have been made on by-products in the production of styrenesulfonate monomers, but the initiator used when polymerizing a water-soluble monomer in an aqueous solvent is still a conventional one. Was used. For example, ammonium persulfate, persulfates such as potassium persulfate,
Azobis-based hydrochlorides such as 2,2'-azobis- (2-amidinopropane) dihydrochloride, and peracids such as hydrogen peroxide have been used.

[0003] When such a polymerization initiator is used, ionic impurities such as chloride ions and sulfate ions are contained in an amount of 100 to 5000 ppm and a hue (AP) depending on the amount to be added.
HA) was at least 60, and at worst, at least 200.

For example, when a persulfate is used, the color of the aqueous polymer solution is inferior, and the aqueous solution is contaminated with sulfate ions. Further, in order to obtain a small aqueous solution of a polymer having a molecular weight of about tens of thousands, it is necessary to use a large amount of the polymer, which remains as a large amount of an inorganic salt, and the aqueous solution after polymerization is colored more densely.

On the other hand, when an azobis-based polymerization initiator such as 2,2'-azobis- (2-amidinopropane) dihydrochloride is used, the coloring of the aqueous polymer solution after the polymerization is improved, but the coloration of the aqueous solution of the hydrochloride is reduced. Chloride ion is mixed in a large amount. The aqueous solution of the polymer after polymerization using peracids as a polymerization initiator was colored in the same manner as when a persulfate was used, and there was a problem that a polymer having a high molecular weight could not be obtained due to cleavage of the polymer. . The use of the aqueous polymer solution produced using such a polymerization initiator is greatly limited due to the incorporation of chloride ions and sulfate ions as ionic impurities and the poor hue (APHA) of the aqueous polymer solution. There was a problem.

[0006]

In order to obtain a high-purity aqueous solution of a polymer, impurities are mixed depending on the type of polymerization initiator used in the polymerization process. It has been difficult to produce an extremely pure polystyrene sulfonate aqueous solution even if chlorides, bromides, sulfides, and the like produced as by-products are reduced as much as possible.

Therefore, an object of the present invention is to provide an aqueous solution of polystyrene sulfonate in which chloride ions and sulfate ions are significantly reduced and the hue is improved.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of such a background, and as a result, in order to obtain an aqueous solution of polystyrenesulfonate, a styrenesulfonate monomer was prepared using a specific initiator. Chloride ion by polymerization,
The present inventors have found an aqueous solution of polystyrene sulfonate in which sulfate ions have been significantly reduced and the hue has been improved, and the present invention has been completed.

That is, according to the present invention, the content of chloride ion and sulfate ion in a 20% by weight aqueous solution of polystyrene sulfonate is 1 ppm to 100 ppm and the hue (AP
HA) of 10 to 60, and a method for producing the same.

Hereinafter, the present invention will be described in detail.

In the present invention, chloride and sulfate ions are contained in a 20% by weight aqueous solution of polystyrene sulfonate in an amount of 1 to 100 ppm, more preferably 1 to 50 ppm, and a hue (APHA) of 10 to 60, more preferably 10 to 60 ppm.
ポ リ ス チ レ ン 50.

The concentration of chlorine ions and sulfate ions is 1 ppm
If the amount is less than the above range, a special (for example, ultrafiltration, dialysis, etc.) purification method must be used, which undesirably increases the production cost. If it exceeds 100 ppm, when mixed with other water-soluble resins, these ions exert a salting-out effect and may cause problems such as phase separation, which is not preferable.

If the hue (APHA) is less than 10, it is necessary to perform an adsorption treatment with activated carbon, which undesirably causes a problem that polystyrene sulfonate is adsorbed together. When it exceeds 60, problems such as a decrease in transparency and coloring may occur when applied or mixed to another resin or fiber, which is not preferable.

In the present invention, the following general formula (Where M is Li, Na, K or NH ₄ ) and / or a water-soluble salt of azobiscyanocarboxylic acid and / or 2,2′-azobis {2-methyl-N- [1,1 ′]. -Bis (hydroxymethyl) -2-hydroxyethyl] propionamide as a polymerization initiator to reduce chloride ions and sulfate ions and to provide a polystyrene sulfonic acid having a hue (APHA) of 60 or less. An aqueous salt solution can be produced.

The polymerization initiator used in the present invention includes:
Examples of water-soluble salt-based initiators of azobiscyanocarboxylic acid include 4,4'-azobis- (4-cyanopentanoic sodium), 4,4'-azobis- (4-cyanopentanoic ammonium), 4,4'-azobis- (4-cyanopentanoic potassium), 4,4'-
Azobis- (4-cyanopentanoic lithium) and the like, 2,2'-azobis {2-methyl-N- [1,1'-bis (hydroxymethyl) -2-hydroxyethyl] propionamide} and the like. At least one of these may be used.

In particular, 4,4'-azobis- (4-cyanopentanoic sodium) and 2,2'-azobis {2-
Methyl-N- [1,1'-bis (hydroxymethyl)-
2-Hydroxyethyl] propionamide is particularly preferably used in terms of cost and coloring. In the present invention, the amount of these additives is 100 styrene sulfonic acid monomers.
With respect to parts by weight, the total amount of the polymerization initiator was 0.0
1 to 20 parts by weight can be used. To obtain a high molecular weight polystyrene sulfonic acid aqueous solution, the addition amount may be reduced, and to obtain a low molecular weight polymer aqueous solution, the addition amount may be increased.

Examples of the styrene sulfonate monomer used in the present invention include sodium styrene sulfonate, potassium styrene sulfonate, ammonium styrene sulfonate, lithium styrene sulfonate and the like. Can be Particularly, sodium styrenesulfonate is preferably used.

The process for producing an aqueous solution of polystyrene sulfonate according to the present invention includes a batch polymerization method in which an aqueous solution in which a styrene sulfonate monomer is dissolved and a polymerization initiator according to the present invention are charged into a polymerization vessel and polymerized. An aqueous solution in which the salt monomer is dissolved, and a sequential addition method in which the polymerization initiator of the present invention is polymerized while being dropped into the polymerization vessel, may be mentioned. However, in the batch polymerization method, it is difficult to remove the polymerization heat of the polymerization reaction, and The addition method is preferably used. The concentration of the polymerization solution of the styrene sulfonate monomer is preferably 5 to 30% by weight in consideration of the production efficiency and the viscosity of the polymer.

The polymerization temperature is sufficient to be that which is carried out in a usual radical polymerization reaction.
It may be performed at 0 ° C., more preferably at 40 to 90 ° C. The polymerization time is preferably 2 to 30 hours.

[0020]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which by no means limit the scope of the present invention.

In the examples, the polymerization rate was determined by measuring the concentration of the styrenesulfonate monomer by a bromine addition method for vinyl groups, and the rest was assumed to be polymerized.

The molecular weight was measured by the GPC method, and the column was measured by using TSK gel GMPWXL. Measurement of ionic impurities by ion chromatography,
The column was quantified using TSKgelIC-Anion-PW.

The hue of the aqueous polymer solution is determined by ASTM D
-1209 (1979). The solids content is 15
The polymer was heated in an oven at 0 ° C. for 30 minutes and determined from the weight loss on heating.

Example 1 280 g of sodium styrenesulfonate (trade name; spinomer NaSS purity: 88.9%) manufactured by Tosoh Corporation was dissolved in 645 g of water. Also, 4,4'-azobis- (4
-0.50 g of cyanopentic sodium) in water 40
g.

Water 1 was added to a polymerization vessel which had been purged with nitrogen in advance.
After the temperature was raised to 90 ° C. while stirring, a sodium styrenesulfonate solution and an initiator solution were added over 4 hours to carry out polymerization. When the addition is complete,
After aging for 2 hours, an aqueous polymer solution was obtained. An aqueous solution of the polymer was obtained which was nearly colorless and transparent. After 6 hours of polymerization, the polymerization rate of sodium styrenesulfonate was 97 mol%, and the weight average molecular weight was 65 × 10 ⁴ .

Then, 2 g of the aqueous polymer solution was heated in an oven at 150 ° C. for 30 minutes, and the solid content was determined from the loss on heating to be 23.2% by weight. Water was added to adjust the concentration to 20% by weight, and the hue (APHA)
Was 20 as measured. The viscosity of the polymer (at 25 ° C.) measured by a B-type viscometer was 1100 cps, and chlorine ions and sulfate ions as impurities in the polymer were 1 each.
0 ppm or less, and 18 ppm. The results are shown in Table 1.

[0027]

[Table 1]

Examples 2 and 3 According to the composition shown in Table 1, the same procedure as in Example 1 was carried out except that a large amount of the initiator used in Example 1 was added. The results are shown in Table 1. Indicated.

As is clear from Examples 1 to 3, the molecular weight can be adjusted by the amount of the initiator used, and the amount of the contaminant ions and the hue of the aqueous solution do not increase even if the amount of the initiator is increased. Is evident.

Example 4 Sodium styrene sulfonate (trade name): NaSS,
280 g of Tosoh Corporation, purity: 88.9%)
g. Further, 2,2'-azobis {2-methyl-N- [1,1'-bis (hydroxymethyl) -2-hydroxyethyl] propionamide} is used as a polymerization initiator.
0.38 g was dissolved in 60 g of water.

In a polymerization vessel purged with nitrogen in advance, 10
After 0 g was charged and the temperature was raised to 85 ° C. while stirring, an aqueous solution of sodium styrenesulfonate and an aqueous solution of an initiator were added over 6 hours to carry out polymerization. After completion of the addition, the mixture was aged for 2 hours to obtain an aqueous polymer solution which was colorless and transparent to the naked eye. The polymerization rate of sodium styrenesulfonate after 8 hours of polymerization is 99 mol%, and the polymerization average molecular weight is 1.56 ×
It was 10 ^6.

The solid content was determined to be 23.3% by weight from the loss on heating of the aqueous polymer solution. The water content was adjusted to 20% by weight, and the hue (APHA) was measured. there were. The viscosity of the polymer aqueous solution measured by a B-type viscometer is 1350 cps (at 25 ° C.), and the content of sulfate ions as impurities in the polymer aqueous solution is 18 ppm.
The results are shown in Table 1.

Example 5 Polymerization was carried out in the same manner as in Example 4 except that the amount of the initiator used in Example 4 was changed according to the formulation shown in Table 1, and the results were shown in Table 1. Indicated.

Comparative Examples 1 to 3 Example 1 was repeated except that the initiator used in Examples 1 to 5 was changed to ammonium persulfate in accordance with the composition shown in Table 1.
The results were shown in Table 1.

It is evident that as the amount of ammonium persulfate used increases, sulfate ions increase, and the hue of the aqueous solution also becomes colored.

From the results shown in Table 1, it is possible to control the molecular weight by using the initiator of the present invention in the same manner as in the case of the usual initiator. It is clear and it is also clear that the colorability of the aqueous polymer solution is improved.

Example 6 880 g of 27% by weight ammonium styrenesulfonate
And 4.76 g of 4,4'-azobis- (4-cyanopentamic ammonium) was dissolved in 30 g of water to prepare an aqueous initiator solution.

Water 1 was placed in a polymerization vessel which had been purged with nitrogen beforehand.
After the temperature was raised to 85 ° C. with stirring, polymerization was carried out by adding ammonium styrenesulfonate solution and initiator solution each for 4 hours. When the addition was completed, the mixture was aged for 3 hours to obtain an aqueous polymer solution.

After 7 hours of polymerization, the conversion of ammonium styrenesulfonate was 97 mol%, and the weight average molecular weight was 15 ×
It was 10 ⁴ . As in Example 1, the viscosity of the polymer (at 25 ° C.) measured with a B-type viscometer after adjusting the concentration to 20% by weight was 1
At 20 cps, chlorine ion and sulfate ion as impurities in the polymer were 10 ppm or less and 22 ppm, respectively. The hue (APHA) of the aqueous solution was 20. Table 2 shows the results.

The ammonium styrenesulfonate was prepared by adding sodium styrenesulfonate to a cation exchange resin Amberlite IR-120B (manufactured by Organo Corporation).
The cation exchange was carried out using styrene, styrenesulfonic acid was obtained once, and an aqueous solution of an equimolar amount of ammonium hydroxide was added.

[0041]

[Table 2]

Example 7 According to the formulation shown in Table 2, the same method as in Example 6 was used except that the amount of 4,4'-azobis- (4-cyanopentanoic ammonium) used in Example 6 was changed. The results are shown in Table 2.

Example 8 Polymerization was carried out in the same manner as in Example 1 except that a 26% by weight aqueous solution of ammonium styrenesulfonate was used in place of the sodium styrenesulfonate used in Example 4, and the results were shown in Table 1. 2 is shown.

Example 9 Polymerization was carried out in the same manner as in Example 8 by changing the amount of the polymerization initiator under the polymerization conditions shown in Table 2, and the results are shown in Table 2.

Comparative Examples 4 to 5 In accordance with the formulation shown in Table 2, the initiator of the present invention used in Examples 6 to 9 was replaced with 2,2'-azobis- (2-amidinopropane) dihydro. Except that chloride (Wako Pure Chemical Industries, Ltd., trade name; V-50) was used, each was carried out in the same manner as in Examples 4 to 5, and the results are shown in Table 2.

[0046]

According to the method of the present invention, it is possible to produce an aqueous solution of polystyrene sulfonate having a significantly reduced chloride ion and sulfate ion and improved hue by polymerization using a specific initiator. It is possible, and it can be used in, for example, the semiconductor field, the photographic field, and the like by reducing impurity ions and improving the hue of the aqueous polymer solution.

[0047]

Claims (2)

[Claims] An aqueous solution of 20% by weight of polystyrene sulfonate having a chlorine ion and sulfate ion content of 1 ppm to 1 ppm.
100 ppm and a hue (APHA) of 10 to 6
An aqueous solution of polystyrene sulfonate, which is 0. 2. The following general formula: (Where M is Li, Na, K or NH ₄ ) and / or a water-soluble salt of azobiscyanocarboxylic acid and / or 2,2′-azobis {2-methyl-N- [1,1 ′]. -Bis (hydroxymethyl) -2-hydroxyethyl] propionamide as a polymerization initiator in an amount of 0.01 to 20 parts by weight based on 100 parts by weight of the styrene sulfonate monomer. Item 6. The method for producing an aqueous solution of polystyrene sulfonate according to Item 1.