JPH02296804A - Production of aqueous sulfonated polymer - Google Patents

Abstract

PURPOSE:To produce an aqueous sulfonated polymer stabilized by decreasing a change in the pH with time by heat-treating a sulfonated aromatic polymer at a specified pH. CONSTITUTION:5-50wt.% aromatic polymer of an aromatic ring content >=10wt.% and an MW of 1000-2000000 (e.g. PS) is dissolved in an aliphatic halogenated hydrocarbon (e.g. 1,2-dichloroethane), and 0.4-2mol, per mol of the aromatic rings, of a sulfonating agent (e.g. sulfuric anhydride) is added to the solution and reacted at 0-80 deg.C for 2-20hr to sulfonate the polymer. A neutralizing agent (e.g. triethylamine) is added to the reaction product and the mixture is dissolved or dispersed in 0.5-30 pts.wt., per pt.wt. aromatic polymer, water. The solvent is distilled off to obtain an aqueous sulfonated polymer. An alkali is added thereto to adjust its pH to 7 or above, and the obtained mixture is heat-treated at 50 deg.C or higher for 2-5hr.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a stable aqueous sulfonated aromatic polymer liquid. More specifically, the present invention relates to a method for producing a stable sulfonated aromatic polymer aqueous liquid with little pH decrease.

[Prior Art] Conventionally, as a method for producing an aqueous sulfonated aromatic polymer liquid, a solution of polystyrene in 1,2-dichloroethane is sulfonated, water is added to the resulting sulfonic acid aqueous solution, and an aqueous calcium hydroxide dispersion is added to the pH 2. A method is known in which the pH is adjusted to 7 to 7.5 with sodium hydroxide after stirring (for example, JP-A-83-189404).

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

[Means for Solving the Problems] The present inventors have arrived at the present invention as a result of intensive research into a method for producing an aqueous sulfonated aromatic polymer liquid with little pH decrease.

That is, the present invention is a method for producing a stable sulfonated aromatic polymer aqueous liquid, which is characterized in that the aromatic polymer is sulfonated and then heat-treated at pH 7 or higher.

The present invention will be explained in more detail below.

The aromatic polymer in the present invention may be any polymer having an aromatic nucleus in its main chain or side chain (for example, vinyl aromatic polymer 1. aromatic polyether, aromatic polyester, etc.).

Examples of the vinyl aromatic polymer include styrene polymers or copolymers, α-methylstyrene polymers or copolymers, and the like. Examples of the styrene copolymer or α-methylstyrene copolymer include styrene or α-methylstyrene and (meth)acrylic acid alkyl ester [
(Meth) acrylate, (meth) ethyl acrylate, (meth) butyl acrylate, (meth) acrylate 2-ethylhexyl, (meth) acrylate stearyl, etc., fatty acid vinyl [vinyl acetate, etc.], aromatic carbonization Hydrogen compounds [vinylnaphthalene, vinyltoluene,
p-methylstyrene, unsaturated carboxylic acids or their anhydrides [(meth)acrylic acid, maleic anhydride, itaconic anhydride, etc.], olefins [α-olefin,
isoprene, imbutylene, diisobutylene, butadiene, piperylene, chloroprene, etc.], and copolymers with nitrile group-containing monomers [(meth)acrylonitrile, etc.].

Examples of the aromatic polyether include poly(2,B-dimethylphenylene ether).

Examples of the aromatic polyester include polyethylene terephthalate, polyethylene isophthalate, polypropylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, polycyclohexylene dimethylene terephthalate, polyethylene-2, and tonaphthalate.

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 styrene monomer unit content 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% based on the weight of the polymer.
% or more, preferably 20% or more.

The molecular weight of the aromatic polymer is usually t,ooo to 2,00
0.000, preferably 2,000~t,ooo,
It's ooo. In the case of styrene polymers or styrene copolymers, the molecular weight is usually 1,000 to 2,000,0
00, preferably 2,000 to 100.0000. In the case of aromatic polyethers, the molecular weight is usually l,
000~l, 00G, 000, preferably 2°000~
Soo, ooo.

In the case of aromatic polyester, the molecular weight is usually 1.00.
0-1,000. Goo, preferably 2,000~
It is 500.000.

In the present invention, the aromatic polymer is sulfonated in solution. As a solvent for making a solution, for example, a carbon number of 1
Examples include those that are inert to the sulfonating agent, such as aliphatic halogenated hydrocarbons having 1 to 2 carbon atoms and nitrated aliphatic hydrocarbons having 1 to 3 carbon atoms. Examples of the aliphatic halogenated hydrocarbons include 1,2-dichloroethane, methylene dichloride, ethyl chloride, carbon tetrachloride, 1,1-dichloroethane, 1,1
, 2.2-tetrachloroethane, chloroform, ethylene dipromide and the like. As nitrated aliphatic hydrocarbons, nitromethane, nitroethane,! -nitroflupane, 2-nitropropane, and the like. Preferred solvents are aliphatic halogenated hydrocarbons.

The dissolution of aromatic polymers depends on the molecular weight of the polymer, but
Usually 1 to 10 aromatic polymers per 100 parts by weight of solvent.
0 parts by weight, preferably 5 to 50 parts by weight.

Sulfuric anhydride is preferably used as the sulfonating agent. Liquid sulfuric anhydride, liquid sulfuric anhydride mixed with an inert gas such as nitrogen or dry air, and a solvent inert to the sulfonating agent such as an aliphatic halogenated hydrocarbon having 1 to 2 carbon atoms such as 1,2-dichloroethane or ethyl chloride. Anhydrous sulfuric acid diluted with The concentration of sulfuric anhydride diluted with inert gas is usually 1-
15% by volume, preferably 3-5% by volume. The concentration of sulfuric anhydride diluted with an inert solvent is usually 1 to 50% by weight,
Preferably it is 5 to 20% by weight.

Moreover, a complex of sulfuric anhydride and Lewis base can also be used. As a Lewis base, trialkyl phosphate (triethyl phosphate, trimethyl phosphate, etc.)
, fatty acid alkyl esters (ethyl acetate, ethyl palmitate, etc.), ethers or thioethers (dioxane, thioxane, diethyl ether, etc.). 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 moles per mole of aromatic nucleus unit in the aromatic polymer.
Preferably, the amount is 0.5 to 1.5 molar. If the amount of the sulfonating agent is less than 0.4 mol, the dispersibility of the sulfonated reaction product in water will be poor. Furthermore, when the amount of the sulfonating agent exceeds 2 moles, by-products such as sulfur sulfate increase.

When using a complex of anhydrous sulfuric acid and a Lewis base, the amount of Lewis base used is usually 0.01 to 0.01 to 1,000 to 1,000 molar based on the mole of aromatic nucleus units constituting the total aromatic polymer used in the reaction.
1 molar amount, preferably 0.02 to 0.5 molar amount.

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

Below, a method for obtaining a sulfonation reaction product of an aromatic polymer will be exemplified.

A monoaromatic polymer is dissolved in an aliphatic halogenated hydrocarbon such that the concentration of the polymer in the solvent is typically in the range of 5 to 50% by weight. A fatty, group halogenated hydrocarbon solvent and optionally a Lewis base are added to the sulfonation reactor. Next, equal amounts of the polymer solution and sulfuric anhydride are added simultaneously to the reactor, usually over a period of 2 to 20 hours. The reaction temperature is usually maintained at 10-50°C. As the reaction progresses, the sulfonated reactant precipitates as a solvent-insoluble substance.

The sulfonation reaction product obtained as described above can be used as it is or as a hydroxide or carbonate of alkali metals or alkaline earth metals, or ammonia, amines (alkylamines such as triethylamine, dimethylamine, laurylamine, After adding a neutralizing agent such as stearylamine; alkanolamine (eg, monoethanolamine, jetanolamine, etc.), it is dissolved or dispersed in water or an aqueous solution of the neutralizing agent. The reactant can be dissolved or dispersed by gradually adding the reactant to water or the above neutralizing agent aqueous solution while stirring, or by adding water or the above neutralizing agent aqueous solution to the sulfonation reactant. can be done.

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

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

In the case of solvent separation by distillation, the sulfonated polymer aqueous liquid is heated while stirring and mixing, and the solvent is distilled out under normal pressure or reduced pressure.

The sulfonated polymer aqueous liquid obtained in this way was
pH 7 or more, preferably 8 or more, more preferably 10
Adjust as above and heat treat. As a pl adjuster,
Alkali metal hydroxides, carbonates, phosphates, phosphates, ammonia, various amine salts, etc. are used. The pn-adjusted sulfonated polymer aqueous solution is typically at a temperature of 50°C.
℃ or higher, preferably 80℃ or higher, more preferably 10℃ or higher
Heat treatment at 0°C or higher. The heat treatment is usually carried out at 8 (1-180°C) in consideration of the pressure resistance of the heat treatment equipment.The required heat treatment time varies depending on the temperature and adjusted pH, but is usually 2 to 5 hours. .

Heat treatment can also be performed before solvent removal.

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

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

Examples 1-3 As a sulfonation reactor, 1,2-dichloroethane 1 was placed in a 3 L four-necked flask equipped with a stirrer and a thermometer.
040 g and triethyl phosphate 9.1 g (0,05
mol) was added. In addition, polystyrene (molecular weight 20
,000) 104g (1.0 mol as an aromatic nucleus unit constituting polystyrene) in 1,2-dichloroethane9
It was dissolved in 36 g to obtain a solution.

The temperature in the reactor was maintained at 20-25° C., and 4 g (0.05 mol) of liquid sulfuric anhydride was gradually added dropwise. next,
1040g of solution A and 80g of liquid sulfuric anhydride (1,(
1 ml) was added dropwise at the same time. The dropping rate was 41
8g/hour, sulfuric anhydride was adjusted to a rate of 32g/hour. During the dropping process, cool down to a temperature of 18-22°C.
It was kept at ℃.

The sulfonated polystyrene precipitated as it formed. After the sulfonation was completed, the dispersion slurry of sulfonated polystyrene was gradually added to 481 g of an aqueous solution containing 44 g of sodium hydroxide at a temperature of 30° C. while stirring. The pll of the resulting neutralized mixture was 2.5. The neutralized mixture was further heated to 105° C. under normal pressure until the odor of 1,2-dichloroethane in the aqueous solution of the sulfonated reaction product disappeared, and 1,2-dichloroethane was distilled off. Next, with an aqueous sodium hydroxide solution, p
B, respectively 8.0. After adjusting the temperature to 10.0° and 12.0°, heat treatment was performed at a temperature of 120°C for 2 hours. After heat treatment, pus with sodium hydroxide.

The concentration was adjusted to 0, and water was added to adjust the concentration to 30%. The resulting aqueous liquid was kept at a constant temperature of 35°C for one month, and then the degree of decrease in pH was measured. The results are shown in Table-1.

Comparative Examples 1 to 2 The pB of the sulfonated polystyrene aqueous solution obtained by carrying out the sulfonation step and the solvent distillation removal step in the same manner as in Examples was adjusted to acidic [i, 0. After adjusting to 3.0, heat treatment was performed under the same conditions as in the example to adjust the pH and concentration.

Tests were conducted under the same conditions as in Examples, and the decrease in pH was measured.

The results are also shown in Table-1.

Table 1 [Effects of the Invention] According to the present invention, it is possible to obtain a stable aqueous sulfonated aromatic polymer liquid with little oral change in pH. As a result, the complexity of having to adjust the pH during use is eliminated. This also increased the durability of iron transport pipes, pumps, etc.

Because it exhibits the above effects, the sulfonated aromatic polymer aqueous liquid obtained by the present invention is useful for applications such as antistatic agents for paper or resin, dispersants for inorganic and organic pigments, and water reducers for concrete. .

Claims (1)

[Claims] 1. A method for producing a stable sulfonated aromatic polymer aqueous liquid, which comprises sulfonating the aromatic polymer and then heat-treating the aromatic polymer at a pH of 7 or higher.