JP2725400B2 - Method for producing water-soluble cationic polymer - Google Patents

Description

The present invention relates to a method for producing a water-soluble cationic polymer, wherein the water-soluble cationic polymer is used as a flocculant as a cationic polyelectrolyte. Dyeing aids in the textile industry, papermaking industry, etc., fiber improving agents, drainage improvers during papermaking, useful as a retention agent for sizing agents, the water-soluble cationic polymer obtained in the present invention is It is used in industries that require a flocculant and in the textile and paper industries.

In particular, quaternized aminoalkyl acrylates alone or polymers of them with acrylamide have an excellent effect on dehydration of hardly dewatered sludge, and those water-soluble cationic polymers obtained by the method of the present invention are It is widely used in industries requiring sludge treatment.

[Prior art] As the water-soluble cationic polymer used in the industry, a solid, especially a powder having good handling and storage stability is desired, and a quaternary used for dehydration of hardly dewatered sludge. In addition to the above-mentioned properties, it is desired that a polymer of an aminoalkyl acrylate alone or a polymer thereof and acrylamide has a relatively low molecular weight and good reactivity.

Methods for producing a solid water-soluble cationic polymer include: (1) a method in which a gel after aqueous solution polymerization is dried with hot air or the like to remove water, or a hydrophilic organic solvent that does not dissolve the polymer is added to extract water. And azeotropic removal by adding an azeotropic solvent with water.

(2) A method of directly filtering and drying after reverse phase emulsion polymerization and reverse phase suspension polymerization, or dehydrating by an appropriate method described above, and then filtering.

(3) A method of drying the polymer by filtration from a solvent after precipitation polymerization.

And various other methods are employed.

[Problems to be Solved by the Invention] Among the above-mentioned production methods, in the case of using an organic solvent in the polymerization and drying steps, the temperature and pressure of the reaction system due to the occurrence of sudden polymerization, polymerization temperature, mistakes in drying temperature management, etc. Water-soluble polymerization that does not use an organic solvent is industrially problematic because it raises the risk of explosion, fire, abnormal fire, the economical necessity of using expensive organic solvents, and environmental hygiene for workers. Is advantageous.

However, when a relatively low molecular weight cationic polymer is obtained by aqueous solution polymerization, the resulting water-soluble hydrated gel is not self-supporting, and exhibits fluid and very large tackiness.
After the polymerization, workability such as removal from the reaction vessel, fragmentation and drying may be significantly deteriorated. For this reason, in order to solve such a problem of workability, when an attempt is made to polymerize a relatively high-concentration aqueous monomer solution, the polymerization reaction occurs violently,
The temperature of the system rises sharply due to the heat of polymerization, and when it exceeds about 100 ° C, it becomes a boiling state in the gel state, and the dangerous phenomenon that the gel expands beyond the reactor volume due to the release of water vapor from the inside of the gel. Occur.

In addition, a gel effect phenomenon, in which the degree of polymerization is remarkably increased due to an increase in the viscosity of the solution, is added, so that the temperature control becomes more difficult.

Solution to Problem The present invention solves the above-mentioned problems that occur when producing a water-soluble cationic polymer in aqueous solution polymerization, and seeks a method for producing a water-soluble cationic polymer which has excellent productivity, excellent workability, and excellent physical properties. The purpose is to do so.

(B) Configuration of the Invention [Means for Solving the Problems] In view of the above-mentioned circumstances, the present inventors have conducted various studies to achieve the above object, and as a result, have added a relatively high-concentration aqueous monomer solution. The present invention solves the above-mentioned problems by performing polymerization while preventing the reaction system from boiling under pressure, and finds that a water-soluble cationic polymer exhibiting excellent physical properties with excellent productivity and workability can be obtained. It was completed.

That is, the present invention provides a method for producing a water-soluble cationic polymer, which comprises obtaining a gel polymer by solution-polymerizing a cationic monomer or a monomer mixture containing a cationic monomer while preventing boiling of an aqueous medium by applying pressure. It is about the method.

 Hereinafter, the present invention will be described in detail.

○ Cationic monomer The cationic monomer to be polymerized in the present invention or the monomer mixture containing the cationic monomer is an unsaturated quaternary ammonium salt such as alkylaminoalkyl (meth) acrylate, alkylaminoalkylacrylamide or dialkyldiallylammonium. Cationic monomers such as halides and alkylaminoallyl halides
Species or a mixture of two or more thereof, or one or more of these cationic monomers and an ethylenically unsaturated monomer copolymerizable therewith, for example, acrylamide, methacrylamide, water-soluble monomers such as vinyl acetate, It is a mixture with an acrylate such as methyl acrylate and a methacrylate such as methyl methacrylate.

Cationic monomers suitable for the production method of the present invention include unsaturated quaternary ammonium salts, and particularly preferred are aminoalkyl (meth) acrylate monomers represented by the following general formula (1). I can do it.

In the formula, R represents a hydrogen atom or an alkyl group; R ₁ represents a hydrogen atom, an alkyl group or an aralkyl group;
R ₂ and R ₃ represent the same or different alkyl groups, X ⁻ is a negative group derived from halogen, monoalkyl sulfate or mineral acid,
n shows a positive integer.

Particularly preferred for the present invention are those wherein R in the formula is a hydrogen atom or a methyl group, and R ₁ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms or an aralkyl group;
R ₂ and R ₃ are an alkyl group having 1 to 4 carbon atoms, and n is 1 to 4
belongs to.

Aminoalkyl (meth) represented by the general formula (1)
Specific examples of the acrylate monomer include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, diethylaminopropylethyl (meth) acrylate, and the like. Quaternary ammonium salts quaternized with benzyl chloride, methyl bromide, ethyl bromide, dimethyl sulfate, diethyl sulfate, or the like, or tertiary amino salts treated with hydrochloric acid, sulfuric acid, acetic acid, and the like. Specific examples include the following. (Meth) acryloyloxyethyltrimethylammonium chloride, (meth) acryloyloxyethyldimethylbenzylammonium chloride, (meth) acryloyloxyethyltrimethylammonium bromide, (meth) acryloyloxyethyltrimethylammonium methylsulfate, (meth) acryloyloxyethyldimethylethyl Ammonium ethyl sulfate, (meth) acryloyloxyethyltrimethylammonium bromide, (meth) acryloyloxyethyldimethylethylammonium chloride, (meth) acryloyloxyethyldimethylamine hydrochloride, (meth) acryloyloxyethyldimethylsulfate, etc. is there.

The copolymerization ratio at the time of copolymerization with the ethylenically unsaturated monomer may be set arbitrarily as long as the produced polymer does not lose water solubility, and the limit is determined according to the type of the monomer to be copolymerized.

○ Pressure conditions The present invention is characterized in that solution polymerization of a cationic monomer or a monomer mixture containing a cationic monomer is performed while preventing the aqueous medium from boiling by pressurization. As the pressurizing pressure for preventing boiling, the boiling of the reaction diameter (aqueous solution) containing the monomer solution or the polymer formed by polymerization of the monomer solution and the monomer solution, particularly the boiling of the aqueous medium, is sufficiently prevented. It must be able to do it.

By applying such pressure, it is possible to produce a hydrogel having uniformity, good self-sustainability, no stickiness and good drying efficiency without boiling the gel. The specific pressurizing pressure varies depending on the concentration of the monomer solution and the polymerization start temperature, and the pressure at the time of boiling varies. Therefore, the pressurizing pressure may be appropriately set so as to prevent the boiling. it is preferred to use more than 0.5 kg / cm ² G as pressure, more preferably a polymerization pressure of 1~4kg / cm ² G. The upper limit of the pressurization is not limited by the properties of the resulting cationic polymer, but is determined mainly from the viewpoint of economical efficiency and difficulty in operation in manufacturing equipment.

The pressurization is performed to prevent the polymerization temperature from becoming high and the aqueous medium from boiling.Therefore, the pressurization condition is adjusted according to the fluctuation of the boiling pressure accompanying the temperature rise due to the heat generated by the polymerization of the monomer solution. However, from the viewpoint of easiness and safety of the operation, it is preferable that the operation is performed by constantly applying the set pressure from the supply of the monomer solution to the reactor to the end of the polymerization.

-Polymerization conditions Solution polymerization in the present invention can be performed by a conventionally known method.

As the solvent, a general aqueous medium, that is, a mixed medium such as water or alcohol miscible with water and water is used.

Known polymerization initiators include, for example, azo compounds such as azobis (2-amidipropane) hydrochloride and azobiosisobutylnitrile, peroxides such as ammonium persulfate and potassium persulfate, and peroxides such as these and ammonium ferrous sulfate. A redox initiator using a sulfite reducing agent such as sodium sulfite in combination is used. The addition amount varies depending on the type and concentration of the monomer, but is usually 0.05 to 0.5% by weight based on the monomer.

The polymerization initiation temperature is not particularly limited and may be set according to the initiator used, and may be set to a temperature at which the reaction rate does not significantly decrease.

After the completion of the polymerization, the obtained water-containing gel of the polymer is cooled until the reaction system containing the formed polymer does not boil even at atmospheric pressure, and then the pressure inside the reaction vessel is returned to atmospheric pressure, and then the reaction vessel is inverted or It is withdrawn by scraping from the reaction vessel. Alternatively, after the reaction system containing the produced polymer is cooled until it no longer boils at atmospheric pressure, it may be extruded using the pressure applied in the reaction vessel. The extracted gel is subjected to a heating or cooling treatment as required, and then cut by a shredder or an extruder. The shredded hydrogel is dried in a high-temperature dryer, a drum-type rotary dryer, or a belt dryer, for example, at a temperature of 40 to 130 ° C., preferably 60 to 100 ° C., and has a water content of 15% by weight or less, preferably 10% by weight. %, And then pulverized to obtain a powdered product.

[Action] According to the present invention, in which solution polymerization is carried out while preventing the aqueous medium from boiling under pressure, the polymerization reaction proceeds in a controlled manner with a high-concentration monomer solution, and the gel has good self-sustainability and tackiness. No drying and good drying efficiency. A hydrogel is produced. In particular, the hydrogel during the polymerization reaction has an excellent effect that the hydrolysis reaction and the cross-linking reaction do not proceed even at a high temperature, and a high-performance polymer can be produced.

EXAMPLES Next, the present invention will be specifically described with reference to examples, but the present invention is not limited by the following examples unless it exceeds the gist.

Example 1 A 51% by weight aqueous solution of acryloyloxyethyltrimethylammonium chloride and acrylamide at a weight ratio of 7/3 was blown with nitrogen for 1 hour while maintaining the temperature at 10 ° C. in a pressure polymerization reactor to perform degassing. Subsequently, 1000 ppm of azobis (2-amidinopropane) hydrochloride, 50 ppm of ammonium persulfate and 50 ppm of sodium sulfite were added, and the pressure was increased.
Polymerization was performed under 1 kg / cm ² G. The temperature of the system rose to 114 ° C. and the polymerization was completed after 30 minutes.

After the hydrogel was cooled below the boiling point, the pressure in the reaction vessel was returned to atmospheric pressure, and then the reactor was inverted to take out the contents. When the hardness of the gel obtained at 50 ° C. was measured with a card meter, the gel was 1.05 × 10 ⁵ dyne / cm ^2, a hard, non-adhesive gel, with good shredding properties, and 2 hours of hot air at 60 ° C. And dried. When the cation density of the obtained polymer was measured by a colloid titration method, the theoretical ratio was 0.98, and almost no hydrolysis occurred. An additional 0.5
% Of the aqueous solution of the polymer was filtered through an 80 mesh wire gauze.

Comparative Example 1 A 51% by weight aqueous solution of acryloyloxyethyltrimethylammonium chloride and acrylamide at a weight ratio of 7/3 was blown with nitrogen for 1 hour in a stainless steel container while maintaining the temperature at 10 ° C. to perform degassing. Subsequently, 1000 ppm of azobis (2-amidinopropane) hydrochloride, 50 ppm of ammonium persulfate, and 50 ppm of sodium sulfite were added, and polymerization was performed under normal pressure.

The gel popped out at 105 ° C during the reaction. Gel hardness, tackiness and gel processability were worse than in Example 1.

Also, the cation density was 0.80 with respect to the theoretical ratio, indicating that hydrolysis had occurred. In addition, the insoluble content was 3 ml, and the solubility was deteriorated.

Comparative Example 2 A 40% by weight aqueous solution of acryloyloxyethyltrimethylammonium chloride and acrylamide at a weight ratio of 7/3 was blown with nitrogen for 1 hour in a stainless steel container while maintaining the temperature at 10 ° C. to perform degassing. Subsequently, 1000 ppm of azobis (2-amidinopropane) hydrochloride, 45 ppm of ammonium persulfate, and 45 ppm of sodium sulfite were added, and polymerization was performed under normal pressure.

The temperature of the system rose to 88 ° C. and the polymerization was completed after 30 minutes. The contents were taken out, and the hardness of the gel obtained at 50 ° C was measured with a card meter.The gel was 0.6 x 10 ⁵ dyne / cm ^{2, which was} a soft and sticky gel. Shredding property deteriorated remarkably. Drying with hot air of 60 ℃
6Hr was required. When the cation density of the obtained polymer was measured by a colloid titration method, the theoretical ratio was 0.99, and almost no hydrolysis occurred. An additional 0.5
% Of the aqueous solution of the polymer was filtered through an 80 mesh wire gauze.

Examples 2 to 4 Pressure polymerization was carried out in the same manner as in Example 1 while changing the pressure (Example 2) and the monomer concentration (Examples 3 and 4). Table 1 summarizes the results of Examples 1 to 4 and Comparative Examples 1 and 2.

(C) Effects of the Invention The water-soluble cationic polymer obtained by the present invention is a flocculant as a cationic polyelectrolyte, a dyeing aid in the textile industry or papermaking industry, a fiber improving agent, and a drainage improver in papermaking. The quaternary aminoalkyl acrylate alone or a water-soluble cationic polymer obtained from this and acrylamide has an excellent effect on the dewatering of hardly dewatered sludge. Therefore, it is widely used in industries that require a flocculant and in the textile and paper industries.

In addition, the water-soluble cationic polymer obtained by the present invention is a solid, especially a powder having good handling and storage stability, and can be used alone or as a quaternary aminoalkyl acrylate used for dehydration of hardly dewatered sludge. Polymers of acrylamide and acrylamide have relatively low molecular weight and good reactivity.

As described above, the present invention is a method for producing a water-soluble cationic polymer exhibiting excellent physical properties.However, since it is excellent in productivity and workability, not only the above-mentioned industry but also a water-soluble cationic polymer can be used. It is a great contribution to the manufacturing chemical industry.

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Claims (1)

(57) [Claims] 1. A water-soluble cationic polymer, which comprises subjecting a cationic monomer or a monomer mixture containing a cationic monomer to solution polymerization while preventing the aqueous medium from boiling by pressurization to obtain a gel polymer. Production method.