JP2024119124A - Method for producing ammonium styrene sulfonate - Google Patents

Abstract

To provide a method for producing ammonium styrene sulfonate, which is simple and environment-friendly.SOLUTION: A method for producing ammonium styrene sulfonate comprises: mixing and dissolving lithium styrene sulfonate and an inorganic ammonium salt in water in the presence of 5 mole% or less of a polymerization inhibitor relative to an amount of lithium styrene sulfonate; and thereafter filtering crystals of ammonium styrene sulfonate which precipitated by cooling, where a charge ratio of ammonium cations relative to the amount of lithium styrene sulfonate is 1.00 equivalent to 3.00 equivalents, a total solid in the reaction system is 25.00 wt.% to 40.00 wt.%, a reaction temperature is 30°C-70°C, and a filtration temperature is 5°C-30°C.SELECTED DRAWING: None

Description

The present invention relates to a simple and environmentally friendly method for producing ammonium styrenesulfonate.

Sodium styrenesulfonate is a water-soluble monomer with strong electrolyte properties and surface activity, and is used in a wide range of industrial fields due to its excellent heat resistance and radical polymerization properties.

For example, sodium styrenesulfonate has long been used as a reactive emulsifier in the production of acrylic polymer emulsions for water-based paints and water-based adhesives. When emulsion-polymerizing radically polymerizable monomers such as acrylic acid esters and methacrylic acid esters, the amount of conventional emulsifiers added is reduced, and instead, a small amount of sodium styrenesulfonate is added and copolymerized, thereby improving the colloidal stability of the polymer emulsion and the water resistance of the emulsion coating film. However, if the amount of sodium styrenesulfonate added is increased to further improve colloidal stability, problems caused by sodium salts such as a decrease in the water resistance of the emulsion coating film and corrosion of iron nails used in wooden buildings may occur (for example, Non-Patent Document 1). Therefore, most of the anionic emulsifiers used in the production of acrylic emulsions are non-metallic ammonium salts with low hygroscopicity (for example, Patent Documents 1 and 2).
In addition, sodium polystyrene sulfonate, which is a polymer of sodium styrene sulfonate, is used in electronic material applications such as dispersants for carbon nanotubes, chemical mechanical polishing (CMP) slurries for semiconductor substrates, and cleaning agents after polishing (e.g., Patent Documents 3 to 5). However, in particular in semiconductor applications, metal and halogen components are required to be as free as possible from the substrate, as they can cause defects and corrosion in the substrate (e.g., Patent Document 6). Therefore, ammonium salts of polystyrene sulfonate that contain as little metal and halogen components as possible are more preferred.

In light of the above, there is a strong market need for ammonium styrenesulfonate, and methods for its production have been proposed to meet this need (e.g., Patent Documents 7 and 8, Non-Patent Document 2).

In Patent Document 7, for example, sodium styrenesulfonate and ammonium sulfate are dissolved and mixed in methanol at 60°C to cause a cation exchange reaction, and then cooled to 30°C to precipitate sodium sulfate produced by cation exchange. It is described that the precipitated sodium sulfate is then filtered off to recover a methanol solution of ammonium styrenesulfonate, and the methanol solution is concentrated to dryness to obtain ammonium styrenesulfonate solids. This method is described as utilizing the difference in solubility in methanol between ammonium styrenesulfonate and sodium sulfate produced by cation exchange. However, the total reaction substrate concentration is low at about 9 wt%, and the concentration to dryness takes time, so polymers are easily produced during this time, and there are also issues with using methanol, which is toxic and flammable, as the reaction solvent.

In Patent Document 8, for example, paratoluidine hydrochloride is added to an aqueous solution of sodium styrenesulfonate, and the toluidine styrenesulfonate salt precipitated by salt exchange is recovered. The toluidine salt is then poured into an aqueous ammonia solution to perform salt exchange again, thereby obtaining an aqueous solution of ammonium styrenesulfonate. However, since toluidine, which is harmful and prone to coloration, is used, and the toluidine styrenesulfonate salt is solubilized in water by ammonium styrenesulfonate, contamination of ammonium styrenesulfonate with toluidine was unavoidable. Also, as in Patent Document 7, when water is distilled off from an aqueous solution containing ammonium styrenesulfonate at a low concentration of about 10% by weight to precipitate ammonium styrenesulfonate crystals, there was a problem that polymers were easily generated.

In Non-Patent Document 2, for example, hydrogen chloride gas is blown into sodium styrenesulfonate dispersed in acetone to convert sodium styrenesulfonate into acetone-soluble styrenesulfonic acid and acetone-insoluble sodium chloride, and then the sodium chloride is filtered off to recover an acetone solution of styrenesulfonic acid, which is further neutralized with ammonia to obtain ammonium styrenesulfonate. However, there are problems in that a highly flammable organic solvent, toxic hydrogen chloride gas and ammonia gas are used, and furthermore, ammonium chloride is inevitably mixed into ammonium styrenesulfonate due to hydrogen chloride remaining in the acetone solution of styrenesulfonic acid.
Another major problem is that the reaction intermediate styrenesulfonic acid is highly susceptible to spontaneous polymerization, making it difficult to avoid polymer contamination (e.g., Non-Patent Document 3).

Due to the above issues, ammonium styrenesulfonate has not yet been industrially produced, and there has been a strong demand for a simple, environmentally friendly method for producing ammonium styrenesulfonate.

Patent No. 3585588 Patent No. 3460246 Patent No. 5482194 Patent No. 6618355 JP 2021-44537 A International Publication No. 2020/184306 Japanese Unexamined Patent Publication No. 149642/1983 Japanese Patent Application Publication No. 51-26842

Jose M. Asua;European Polymer Journal, 2017, Vol. 93, pp. 480-494 Oriental Soda Research Report, Vol. 24, No. 1, 1980, pp. 3-11 J.C.Salamone;Polymer Letters Edition, Vol. 15, 1977, pp. 487-491

The present invention was made in consideration of the above background and problems, and aims to provide a simple and environmentally friendly method for producing ammonium styrenesulfonate.

As a result of intensive research, the inventors have discovered that ammonium styrenesulfonate can be produced by dissolving and mixing lithium styrenesulfonate and an inorganic ammonium salt in water under specific conditions, followed by cooling and crystallization, without using harmful and dangerous organic solvents or gases, and without going through strong acidic conditions that tend to produce polymers, and have completed the present invention. Note that the lithium styrenesulfonate referred to below is usually the para form, but as is commonly known, it also includes positional isomers such as the meta form and ortho form.

That is, the present invention relates to the following.
[1] A method for producing ammonium styrenesulfonate, comprising mixing and dissolving lithium styrenesulfonate and an inorganic ammonium salt in water in the presence of 5 mol% or less of a polymerization inhibitor relative to the amount of lithium styrenesulfonate, and then filtering off the precipitated ammonium styrenesulfonate crystals by cooling,
The ratio of the amount of ammonium cation to the amount of lithium styrenesulfonate is 1.00 equivalents to 3.00 equivalents;
The total solid content in the reaction system is 25.00% by weight to 40.00% by weight,
The reaction temperature is 30° C. to 70° C., and the filtration temperature is 5° C. to 30° C.;
Method for producing ammonium styrenesulfonate.
[2] A method for producing ammonium styrenesulfonate, comprising mixing and dissolving lithium styrenesulfonate and an inorganic ammonium salt in water in the presence of 2 mol% or less of a polymerization inhibitor relative to the amount of lithium styrenesulfonate, and then filtering out ammonium styrenesulfonate crystals precipitated by cooling,
The ratio of the amount of ammonium cation to the amount of lithium styrenesulfonate is 1.00 equivalents to 2.00 equivalents;
The total solid content in the reaction system is 30.00% by weight to 40.00% by weight,
The reaction temperature is 30° C. to 60° C., and the filtration temperature is 5° C. to 25° C.;
A method for producing an ammonium styrene sulfonate composition.
[3] The method for producing lithium styrenesulfonate according to item [1] or [2], wherein the polymerization inhibitor is sodium nitrite and/or lithium nitrite.

The manufacturing method of the present invention can produce ammonium styrenesulfonate without using dangerous and harmful raw materials or going through unstable intermediates, making it extremely useful for producing acrylic emulsions and ammonium styrenesulfonate polymers for electronic materials.

The following describes in detail the form for carrying out the present invention (hereinafter, referred to as the "present embodiment"). Note that the present invention is not limited to the present embodiment. The present invention can be carried out with appropriate modifications within the scope of its gist.

The inventors of the present invention focused on the difference in solubility in water between lithium styrene sulfonate (hereinafter sometimes abbreviated as "LiSS") and ammonium styrene sulfonate, and arrived at the present invention.

The production flow of AmSS of the present invention is as follows: First, a reactor is charged with water, LiSS, inorganic ammonium salt, and polymerization inhibitor in a specific composition, and mixed and dissolved at a specific temperature for a specific time while stirring. It was then found that when the mixture is cooled and aged to a specified temperature at a specific rate, AmSS crystals, which have low solubility in water, are preferentially precipitated to form a slurry, while LiSS and inorganic salts, which have high solubility, remain in the mother liquor. In other words, by filtering the slurry, AmSS can be produced easily and at a high concentration without using dangerous and harmful raw materials, going through unstable intermediates, or going through a concentration-drying and heating-drying process. The present invention utilizes the difference in solubility between LiSS and AmSS to perform cation exchange.

Examples of inorganic ammonium salts include ammonium chloride, ammonium bromide, ammonium sulfate, ammonium nitrate, ammonium phosphate, and ammonium acetate. Among these, ammonium chloride and ammonium bromide are more preferred in consideration of the high yield due to the high salting-out effect, and ammonium sulfate, ammonium nitrate, and ammonium phosphate are more preferred in consideration of the residual halogen in AmSS and economic efficiency.

There are no particular limitations on the polymerization inhibitor, so long as it is soluble in water or the reaction solution and inhibits the polymerization of AmSS. Examples include polymerization inhibitors used in the production of sodium styrenesulfonate and LiSS, such as sodium nitrite and lithium nitrite. The amount of polymerization inhibitor added is preferably 5 mol% or less of the amount of LiSS charged, and more preferably 2 mol% or less in consideration of the polymerizability of AmSS. On the other hand, if the amount added is too small, the monomer may polymerize during the reaction, so from the viewpoint of inhibiting polymerization, 0.1 mol% or more, and even more preferably 0.2 mol% or more, is preferred.

The manufacturing conditions will be explained in more detail below.

In the present invention, the ratio of ammonium cations to the amount of LiSS is preferably 1.00 to 3.00 equivalents. If the ratio is less than 1.00 equivalents, the cation exchange rate is insufficient and the salt concentration in the system is reduced, making it difficult to produce good quality crystals with good drainage properties. On the other hand, if the equivalent ratio exceeds 3.00 equivalents, no improvement in drainage properties is observed, and instead the inorganic salt concentration in the attached filtrate increases, and the purity of AmSS may decrease. From the viewpoint of the balance between the inorganic salt concentration in the filtrate and drainage properties, 1.00 to 2.00 equivalents are more preferable.

In the present invention, the total solid content in the reaction system is preferably 25.00% to 40.00% by weight. If the total solid content is less than 25.00% by weight, not only the yield decreases, but also the drainage property may decrease. On the other hand, if the total solid content exceeds 40.00% by weight, the inorganic salt concentration in the filtrate increases, and the purity of AmSS may decrease. Furthermore, from the viewpoint of the balance between the inorganic salt concentration in the filtrate and the drainage property, it is more preferably 30.00% to 40.00% by weight, and even more preferably 35.00% to 40.00% by weight. Here, the total solid content means the sum of the raw materials that are solid at room temperature present in the reaction system, the impurities that are solid at room temperature contained in the raw materials, and the by-products that are solid at room temperature.

In the present invention, the reaction temperature is preferably 25° C. to 75° C. In the above-mentioned charging composition, if the reaction temperature is less than 25° C., the cation exchange rate may be insufficient, and if it exceeds 75° C., the cation exchange rate is improved, but the risk of an increase in the polymer content may increase. Furthermore, 30° C. to 60° C. is more preferable.
The reaction time is preferably 0.5 to 20 hours, and can be adjusted depending on the substrate concentration and reaction temperature, but is more preferably 0.5 to 10 hours in order to prevent spontaneous polymerization during the reaction.
The cooling temperature is preferably 5° C. to 30° C. Furthermore, after reaching a predetermined cooling temperature, aging is further carried out for 0.5 to 5 hours. If the cooling temperature is lower than 5° C., impurities such as inorganic salts and moisture in AmSS may increase, and if it exceeds 30° C., the yield may decrease significantly, so the cooling temperature is more preferably 5° C. to 25° C.
The cooling rate can be adjusted according to the heating temperature and the total solid content, but is preferably 5°C to 30°C per hour. If the cooling rate is too fast, the crystal size becomes small and the drainage property decreases, which may result in an increase in moisture and inorganic salts in the AmSS. On the other hand, if the cooling rate is extremely slow, the crystals may collapse and the drainage property may decrease, so the cooling rate is more preferably 5°C to 20°C per hour.

In the present invention, in order to increase the crystal size of AmSS and improve drainage properties, it is more preferable to use so-called temperature swing crystallization, in which the mixture is cooled to a certain temperature to precipitate crystals, then reheated to a temperature at which all the crystals do not dissolve, and cooled again.
When each raw material is charged into a reactor, it may be charged as a powder, or may be charged as a saturated aqueous solution of each raw material. In addition, the charging method may be either batch charging or sequential charging. Dropping a saturated aqueous solution of an inorganic ammonium salt into an aqueous solution of LiSS reduces the inclusion of inorganic salts into the precipitated AmSS crystals, and high-quality AmSS can be obtained.
There is no need to deoxidize the reaction system, and an air atmosphere will suffice.

In the present invention, a water-soluble organic solvent can be added to increase the yield of AmSS. Examples include alcohols such as methanol, ethanol, and 2-propanol, ketones such as acetone, nitriles such as acetonitrile, and ethers such as tetrahydrofuran. However, from the viewpoint of environmental load and explosion prevention, water alone is preferred for industrial methods.

In the present invention, filtration can be performed by centrifugal filtration, pressure filtration, vacuum filtration, etc., but centrifugal filtration is more preferred because it has a large processing capacity and can be performed in a relatively short time. In addition, impurities can be further reduced by purifying the obtained AmSS composition by recrystallization with water. In this case, the total solid content in the system is preferably 40.00% to 55.00% by weight, the heating temperature is 40°C to 60°C, and the cooling and filtration temperatures are preferably 15°C to 25°C.

The present invention will be explained in more detail with reference to the following examples, but the present invention is not limited to these examples.

<Medicines used>
Lithium styrene sulfonate (LiSS): manufactured by Tosoh Finechem Co., Ltd., purity 85.3%, lithium bromide 2.5% by weight, lithium hydroxide 0.45% by weight, lithium sulfate 0.50% by weight, water 7.1% by weight, polymer content 0.04% by weight, sodium nitrite 60 ppm
Lithium nitrite: Honjo Chemical Co., Ltd., 40% by weight aqueous solution Dimethyl sulfone: Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent

<Quantitative determination of water content in AmSS>
The measurement was performed using an infrared moisture meter under the following conditions.
Apparatus: FD-720 manufactured by Kett Electric Laboratory Co., Ltd.
Conditions: Approximately 5 g of sample was taken and heated at 120° C. for 20 minutes.

<Analysis of AmSS Purity>
The amount of active double bonds was quantified by oxidation-reduction titration to determine the AmSS purity (i.e., including ortho and meta isomers in addition to para isomers).
(1) Instruments and Equipment 1) Weighing bottle: diameter 50 mm, depth 70 mm
2) 500 ml and 1000 ml measuring flasks 3) 500 ml Erlenmeyer flask with stopper 3) Electronic chemical balance (2) Reagents 1) Bromine solution: 22.00 g of potassium bromide (KBr) and 3.00 g of potassium bromate (KBrO ₃ ) were dissolved in pure water to make up to 1000 ml.
2) Sulfuric acid aqueous solution (concentrated sulfuric acid/pure water volume ratio = 1/1)
3) Potassium iodide aqueous solution (200 g/L)
4) 0.1 mol/L sodium thiosulfate aqueous solution 5) Starch aqueous solution: 6.00 g of starch was dissolved in pure water to make up a total volume of 1000 ml.
(3) Procedure 1) Weigh out 20 g of a sample into a weighing bottle to the nearest 0.1 mg.
2) Rinse and transfer to a 500 ml measuring flask with pure water to bring the liquid volume to approximately 400 ml.
3) Add a magnetic rotor and stir to dissolve the sample.
4) Remove the rotor, align the marked lines with pure water, shake and mix to use as the test solution.
5) Add 25 ml of bromine solution to a 500 ml stoppered Erlenmeyer flask containing 200 ml of pure water.
6) After adding 5 ml of the test solution, add 10 ml of an aqueous sulfuric acid solution, seal the vial, and leave it for 20 minutes.
7) Quickly add 10 ml of an aqueous potassium iodide solution and leave to stand for 10 minutes.
8) Titrate with an aqueous sodium thiosulfate solution. After the yellow color of the solution fades, add 1 ml of starch solution as an indicator and titrate until the blue color of the resulting iodine starch disappears.
9) As a separate blank test, add 200 ml of pure water to a stoppered Erlenmeyer flask, add 25 ml of bromine solution, quickly add 10 ml of aqueous potassium iodide solution and 10 ml of aqueous sulfuric acid solution, and repeat the procedure in 8).
(4) Calculation The AmSS content is calculated using the following formula.
A=100×[0.01006×(a-b)×f]/(S×5/500)
A: AmSS content (%)
a: Amount of sodium thiosulfate solution required for blank test (ml)
b: Aqueous sodium thiosulfate solution required for this test (ml)
f: titer of sodium thiosulfate aqueous solution S: sample amount (g)

<Elemental analysis of AmSS>
Carbon, hydrogen, and nitrogen contents were quantified using an elemental analyzer. Apparatus: PerkinElmer 2400II

<Quantitative Determination of Sulfur Content of AmSS>
The combustion gas of AmSS burned by the oxygen flask combustion method was absorbed in a hydrogen peroxide absorbing solution to prepare an absorbing solution. The sulfate ion concentration in the absorbed solution was then quantified by ion chromatography (see the next item for measurement conditions) and converted into sulfur content.

<Quantitative determination of bromine, chlorine and sulfate ions in AmSS>
The quantitative analysis was carried out using ion chromatography under the following conditions.
Equipment: Tosoh Corporation, IC-2010
Column: TSKgel (registered trademark) guard column Super IC-AHS (4.6 mm I.D. x 1 cm) + TSKgel (registered trademark) Super IC-Anion HS (4.6 mm I.D. x 10 cm)
Column temperature: 40°C, injection volume: 30 μl, flow rate: 1.5 ml/min
Eluent: carbonate buffer (7.5mM- _NaHCO3 + _{0.8mM-Na2CO3 )}
Preparation of sample solution: The AmSS composition was dissolved in ultrapure water to dilute it 10-fold, and the solution was passed through a pretreatment cartridge (TOYOPAK (registered trademark) ODSM) to prepare a measurement sample.
Calibration curve: Absolute calibration curve method using standard solutions

<Analysis of lithium content of AmSS>
Lithium was quantified using a high frequency inductively coupled plasma atomic emission spectrometer OPTIMA 8300 (manufactured by PerkinElmer) (hereinafter abbreviated as ICP-AES). The target sample was wet decomposed with sulfuric acid and nitric acid, and the decomposed sample was heated to dryness. Nitric acid was added to the dried sample and dissolved by heating. After a predetermined amount was measured, 1 ppm of scandium was added as an internal standard and quantified.

<Analysis of AmSS polymer content>
The analysis was carried out by gel permeation chromatography (GPC) under the following conditions.
Apparatus: Tosoh Corporation HLC-8320
Column: TSKgel® guard column AW-H/TSKgel® Super AW-6000/TSKgel® SuperAW-3000/TSKgel® SuperAW-2500
Eluent: 0.05 M aqueous sodium sulfate solution/acetonitrile = 65/35 (volume ratio) solution Sample: A 1 wt% solution (as is) of the AmSS composition was prepared using the above eluent Flow rate/injection amount/column temperature: 0.6 ml/min, injection amount: 10 μl, column temperature: 40° C.
Detector: UV detector (wavelength 230 nm)
Calibration curve: Using sodium polystyrene sulfonate (PS-1, manufactured by Tosoh Finechem Co., Ltd.) and the above eluent, standard solutions with different concentrations of sodium polystyrene sulfonate were prepared, and a calibration curve was created.

Example 1
A cylindrical 2L glass separable flask equipped with a reflux condenser and a dropping funnel was charged with 541.54 g of LiSS powder, 0.48 g of lithium nitrite (40 wt% aqueous solution), and 745.03 g of ion-exchanged water, and the mixture was stirred for 15 minutes at an internal temperature of 35 ° C. using a stirrer. While maintaining the internal temperature at 35 ° C., an aqueous solution of 150.18 g of ammonium chloride dissolved in 390.06 g of ion-exchanged water was dropped using a dropping funnel over 5 minutes (the ratio of ammonium cation to LiSS was 1.16 equivalents, and the total solid content was 35.78 wt%). After the dropwise addition, the reaction system became a white slurry, but stirring was continued for 1 hour at an internal temperature of 35 ° C. Thereafter, the mixture was cooled to 5 ° C. over 3 hours and aged for 1 hour to obtain a white slurry containing AmSS.
The slurry was then centrifuged (600 G) to obtain 423.65 g of white wet crystals of AmSS. The slurry had good drainability, and the moisture content determined by an infrared moisture meter was 9.62 wt %, and the AmSS content determined by oxidation-reduction titration was 89.2 wt %.

If lithium metal remains in AmSS, it may exist as LiSS, but it is extremely difficult to distinguish between AmSS and LiSS. However, since the lithium content in AmSS was reduced to 0.13% by weight and large plate-like crystals were formed compared to LiSS, which forms fine needle-like crystals, it was determined that the desired AmSS was obtained. The above reaction recipe and details of the results are summarized in Table 1. It is clear that the water, lithium content, halogen content, and polymer content in AmSS are low and of high purity compared to Comparative Examples 1 to 4.

Example 2
AmSS was prepared by changing the reaction temperature and cooling/filtration temperature in Example 1. The details of the formulation and the results are shown in Table 1. It is clear that the water content, lithium content, halogen content, and polymer content in AmSS are low and the purity is high compared to Comparative Examples 1 to 4.

<Comparative Examples 1 to 4>
AmSS was prepared by changing the reaction temperature, cooling/filtration temperature, or total solid content in Example 1. The details of the formulation and the results are shown in Table 1. It is clear that the water content, lithium content, halogen content, and polymer content in AmSS are high and the purity is low compared to the examples.

Claims (3)

A method for producing ammonium styrenesulfonate, comprising mixing and dissolving lithium styrenesulfonate and an inorganic ammonium salt in water in the presence of 5 mol % or less of a polymerization inhibitor based on the amount of lithium styrenesulfonate, and then filtering out ammonium styrenesulfonate crystals precipitated by cooling, comprising the steps of:
The ratio of the amount of ammonium cation to the amount of lithium styrenesulfonate is 1.00 equivalents to 3.00 equivalents;
The total solid content in the reaction system is 25.00% by weight to 40.00% by weight,
The reaction temperature is 30° C. to 70° C., and the filtration temperature is 5° C. to 30° C.;
Method for producing ammonium styrenesulfonate. A method for producing ammonium styrenesulfonate, comprising mixing and dissolving lithium styrenesulfonate and an inorganic ammonium salt in water in the presence of 2 mol % or less of a polymerization inhibitor based on the amount of lithium styrenesulfonate, and then filtering out ammonium styrenesulfonate crystals precipitated by cooling, comprising the steps of:
The ratio of the amount of ammonium cation to the amount of lithium styrenesulfonate is 1.00 equivalents to 2.00 equivalents;
The total solid content in the reaction system is 30.00% by weight to 40.00% by weight,
The reaction temperature is 30° C. to 60° C., and the filtration temperature is 5° C. to 25° C.;
A method for producing an ammonium styrene sulfonate composition. The method for producing lithium styrenesulfonate according to claim 1 or 2, wherein the polymerization inhibitor is sodium nitrite and/or lithium nitrite.