JPH0641487B2 - Method for producing aqueous solution of sulfonated polymer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a stable aqueous sulfonated aromatic polymer liquid. More specifically, it relates to a method for producing a stable aqueous sulfonated aromatic polymer liquid with little pH drop.

[Prior Art] Conventionally, as a method for producing a sulfonated aromatic polymer aqueous solution, a 1,2-dichloroethane solution of polystyrene was sulfonated, and water was added to obtain a sulfonic acid aqueous solution, and an aqueous dispersion of calcium hydroxide was adjusted to pH 2 A method is known in which the pH is adjusted to 7 to 7.5 with caustic soda after adding and stirring so that the amount becomes (see, for example, JP-A-63-189404).

[Problems to be Solved by the Invention] However, the aqueous liquid of the sulfonated polymer obtained by such a method has a problem that the pH decreases with time and must be adjusted before use. .

[Means for Solving the Problems] The inventors of the present invention have arrived at the present invention as a result of earnest studies on a method for producing an aqueous solution of a sulfonated aromatic polymer having a low pH decrease.

That is, the present invention is a method for producing a stable aqueous solution of a sulfonated aromatic polymer, which comprises subjecting an aromatic polymer to sulfonation and then heat-treating it at pH 7 or higher.

Hereinafter, the present invention will be described in more detail.

The aromatic polymer in the present invention may be any polymer having an aromatic nucleus in the main chain or side chain, and examples thereof include vinyl aromatic polymers, aromatic polyethers and aromatic polyesters.

Examples of vinyl aromatic polymers include styrene polymers or copolymers, α-methylstyrene polymers or copolymers. Examples of the styrene copolymer or α-methylstyrene copolymer include styrene or α-methylstyrene and (meth) acrylic acid alkyl ester [methyl (meth) acrylate, ethyl (meth) acrylate, (meth) acrylic Butyl acid, (meth) acrylic acid 2-
Ethylhexyl, stearyl (meth) acrylate, etc.], fatty acid vinyl [vinyl acetate, etc.], aromatic hydrocarbon monomer [vinylnaphthalene, vinyltoluene, p-
Methylstyrene, etc.], unsaturated carboxylic acid or its anhydride [(meth) acrylic acid, maleic anhydride, itaconic anhydride, etc.], olefins [α-olefin, isoprene, isobutylene, diisobutylene, butadiene,
And a copolymer with a nitrile group-containing monomer [(meth) acrylonitrile] and the like.

Examples of aromatic polyethers include poly (2,6-dimethylphenylene ether).

Examples of aromatic polyesters include polyethylene terephthalate, polyethylene isophthalate, polypropylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, polycyclohexylene dimethylene terephthalate, and polyethylene-2,6-naphthalate.

The aromatic nucleus content in the aromatic polymer is usually 10% or more, preferably 20% or more, based on the weight of the polymer. For example, in the case of a styrene copolymer, the content of styrene monomer units in the styrene copolymer is usually 15% or more, preferably 30% or more, based on the weight of the copolymer. In the case of aromatic polyesters, the aromatic nucleus content in the aromatic polyester is usually 10% or more, preferably 20% or more, based on the weight of the polymer.

The molecular weight of the aromatic polymer is usually 1,000 to 2,000,000, preferably 2,000 to 1,000,000. In the case of styrene polymer or styrene copolymer, the molecular weight is usually 1,000 ~
It is 2,000,000, preferably 2,000 to 100,000. For aromatic polyethers, the molecular weight is usually 1,000 to 1,000,0
It is 00, preferably 2,000 to 500,000.

In the case of aromatic polyester, the molecular weight is usually 1,000-
It is 1,000,000, preferably 2,000 to 500,000.

In the present invention, the aromatic polymer is made into a solution and sulfonated. The solvent for forming the solution has, for example, 1 carbon atom.
Examples thereof include those that are inactive to sulfonating agents such as aliphatic halogenated hydrocarbons having 2 to 3 carbon atoms and nitrated aliphatic hydrocarbons having 1 to 3 carbon atoms. Examples of the aliphatic halogenated hydrocarbon include 1,2-dichloroethane, methylene dichloride, ethyl chloride, carbon tetrachloride, 1,1-dichloroethane, 1,1,2,2-
Examples include tetrachloroethane, chloroform, ethylene dibromide, and the like. As the nitrated aliphatic hydrocarbon, nitromethane, nitroethane, 1-nitropropane,
2-nitropropane etc. are mentioned. Preferred solvents are aliphatic halogenated hydrocarbons.

The dissolution of the aromatic polymer depends on the molecular weight of the polymer,
The aromatic polymer is usually dissolved in an amount of 1 to 100 parts by weight, preferably 5 to 50 parts by weight, per 100 parts by weight of the solvent.

Sulfuric anhydride is preferably used as the sulfonating agent. Solvents that are inert to liquid anhydrous sulfuric acid, inert gas such as nitrogen and dry air, and sulfonating agents such as 1,2-dichloroethane and ethyl halogenated aliphatic hydrocarbons such as ethyl chloride Anhydrous sulfuric acid diluted with can also be used. The sulfuric anhydride concentration diluted with an inert gas is usually 1 to 15% by volume, preferably 3 to 5% by volume. The sulfuric acid anhydride concentration diluted with an inert solvent is usually 1 to 50% by weight, preferably 5 to 20% by weight.

It is also possible to use a complex of anhydrous sulfuric acid and a Lewis base. Examples of the Lewis base include trialkyl phosphates (triethyl phosphate, trimethyl phosphate, etc.), fatty acid alkyl esters (ethyl acetate, ethyl palmitate, etc.), ethers or thioethers (dioxane, thioxane, diethyl ether, etc.) and the like. Preferred Lewis bases are trialkyl phosphates, and fatty acid alkyl esters.

In the present invention, the amount of the sulfonating agent used is usually 0.4 to 2 mol, preferably 0.5 to 1.5 mol, per 1 mol of the aromatic nucleus unit in the aromatic polymer. The amount of sulfonating agent
If it is less than 0.4 mol, the dispersibility of the sulfonation reaction product in water becomes poor. Further, when the amount of the sulfonating agent exceeds 2 mol, by-products such as Glauber's salt increase.

When a complex of sulfuric anhydride and a Lewis base is used, the amount of the Lewis base used is usually 0.01 to 1 mol, preferably 1 to 1 mol of the aromatic nucleus unit constituting the total aromatic polymer used in the reaction. , 0.02-0.5 molar amount.

The reaction temperature for the sulfonation is usually 0 to 80 ° C., preferably
10 to 50 ° C. The reaction is performed under anhydrous conditions.

Below, the method of obtaining the sulfonation reaction product of an aromatic polymer is illustrated.

The aromatic polymer is dissolved in an aliphatic halogenated hydrocarbon so that the concentration of the polymer in the solvent is usually in the range of 5 to 50% by weight. To the sulfonation reactor is added a solvent of the aliphatic halogenated hydrocarbon and optionally a Lewis base. Next, the above-mentioned polymer solution and sulfuric anhydride are simultaneously added to the reactor in equal amounts, usually over 2 to 20 hours. The reaction temperature is usually maintained at 10-50 ° C. As the reaction progresses, the sulfonated reaction product is precipitated as a solvent insoluble substance.

The sulfonation reaction product obtained as described above is a hydroxide, carbonate, or ammonia such as an alkali metal or an alkaline earth metal as it is, or an amine (alkylamine such as triethylamine, dimethylamine, laurylamine, Stearylamine and the like; alkanolamines such as monoethanolamine, diethanolamine and the like) are added and then dissolved or dispersed in water or the above-mentioned neutralizing agent aqueous solution. The reaction product is dissolved or dispersed by gradually adding water or the above neutralizing agent aqueous solution to the reaction mixture while stirring, or by adding water or the above neutralizing agent aqueous solution to the sulfonation reaction product. be able to.

The amount of water varies depending on the molecular weight of the aromatic polymer, but is usually 0.5 to 30 parts by weight, preferably 1 to 20 parts by weight, per 1 part by weight of the aromatic polymer.

Then, the solvent is removed by distillation, liquid separation, or the like. In order to reduce the content of the solvent in the sulfonated polymer aqueous liquid, the method of distilling the solvent is preferable.

In the case of solvent separation by distillation, the sulfonated polymer aqueous solution is heated while stirring and mixing to distill off the solvent under normal pressure or reduced pressure.

The sulfonated polymer aqueous liquid thus obtained,
The pH is adjusted to 7 or higher, preferably 8 or higher, more preferably 10 or higher, and heat-treated. As the pH adjuster, alkali metal hydroxides, carbonates, phosphates, borates, ammonia, various amine salts and the like are used. The pH-adjusted aqueous sulfonated polymer solution is heat-treated at a temperature of usually 50 ° C. or higher, preferably 80 ° C. or higher, more preferably 100 ° C. or higher. The heat treatment considers the pressure resistance of the heat treatment device,
It is usually carried out at 80 to 180 ° C. The required heat treatment time is
It is usually 2 to 5 hours, though it varies depending on the temperature and the adjusted pH.

The heat treatment can also be performed before removing the solvent.

The heat-treated aqueous sulfonated polymer solution is adjusted as it is or to a desired pH.

[Examples] Hereinafter, the present invention will be further described with reference to Examples, but the present invention is not limited thereto.

Examples 1 to 3 As a sulfonation reactor, 1040 g of 1,2-dichloroethane and 9.1 g (0.05 mol) of triethyl phosphate were added to a 3 L four-necked flask equipped with a stirrer and a thermometer. Further, 104 g of polystyrene (molecular weight 20,000) (1.0 mol as an aromatic nucleus unit constituting polystyrene) was dissolved in 936 g of 1,2-dichloroethane to obtain a solution A.

Keep the temperature in the reactor at 20 to 25 ° C, and add 4 g of liquid anhydrous sulfuric acid.
(0.05 mol) was gradually added dropwise. Next, 1040 g of solution A and 80 g (1.0 mol) of liquid anhydrous sulfuric acid were simultaneously added dropwise.
The dropping rate was 416 g / hour for Solution A and 32 for sulfuric anhydride.
The ratio was adjusted to be g / hour. During the dropping, the temperature was kept at 18 to 22 ° C by cooling.

The sulfonated polystyrene precipitated as it formed. After the sulfonation is complete, the sulfonated polystyrene dispersion slurry contains 44 g of sodium hydroxide at a temperature
It was gradually added to 481 g of a 30 ° C. aqueous solution while stirring. The pH of the resulting neutralized mixture was 2.5. Further heating the neutralization mixture, 1, in the aqueous solution of the sulfonation reaction product
105-105 under normal pressure until the odor of 2-dichloroethane disappears
The temperature was raised to ° C, and 1,2-dichloroethane was distilled off. Next, with an aqueous sodium hydroxide solution, the pH was adjusted to 8.0 and 10.
After adjusting to 0.12.0, heat treatment was carried out at a temperature of 120 ° C. for 2 hours. After heat treatment, the pH was adjusted to 8.0 with sodium hydroxide, and water was added to adjust the concentration to 30%. With respect to the obtained aqueous liquid, the degree of decrease in pH was measured after a lapse of 1 month at a constant temperature of 35 ° C. The results are shown in Table-1.

Comparative Examples 1-2 After adjusting the pH of the sulfonated polystyrene aqueous solution obtained in the same manner as in the sulfonation step and the solvent distilling and removing step to 6.0 or 3.0, the heat treatment was conducted under the same conditions as in the examples. The pH and concentration were adjusted. The test was carried out under the same conditions as in the example, and the decrease in pH was measured. The results are also shown in Table-1.

[Effects of the Invention] According to the present invention, a stable sulfonated aromatic polymer aqueous solution with little change in pH over time can be obtained. As a result, the complexity of having to adjust the pH at the time of use is eliminated. This also increased the durability of iron transportation pipes, pumps, etc.

From the above effects, the sulfonated aromatic polymer aqueous solution obtained in the present invention is useful for applications such as antistatic agents for paper or resins, dispersants such as inorganic and organic pigments, concrete water reducing agents, etc. .

Claims (1)

[Claims] 1. A pH of 7 after sulfonation of an aromatic polymer.
A method for producing a stable aqueous solution of a sulfonated aromatic polymer, which comprises heat treatment as described above.