JP3216070B2 - Method for producing polymer particle dispersion, method for purifying polymer particles, and method for modifying polymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polymer particle dispersion, a method for purifying a polymer particle, and a method for modifying a polymer. More specifically, the present invention relates to a method for dispersing a water-insoluble polymer particle such as an N-vinylformamide copolymer. The present invention relates to a method for producing a dispersion, a method for purifying polymer particles for separating polymer particles from the dispersion, and a method for modifying a polymer to make a water-insoluble polymer particle a water-soluble or water-swellable polymer.

[0002]

2. Description of the Related Art Polyvinylamine exerts an excellent effect in the field of application of water-soluble polymer substances such as additives for papermaking and flocculants for wastewater treatment. In particular, when used as a coagulant for dehydrating organic sludge, there is an effect that the water content of dehydrated sludge is reduced and the sludge treatment efficiency is significantly improved.
As a method for producing polyvinylamine, Hoffman decomposition of polyacrylamide is conventionally known. Further, it can be produced by hydrolyzing poly N-vinyl formamide obtained by polymerizing N-vinyl formamide (JP-A-58-23809).

[0003] In order to further improve the physical properties of polyvinylamine, acrylonitrile, which is a hydrophobic monomer, is copolymerized with N-vinylformamide, and the formamide group in this copolymer is similarly hydrolyzed. Molecules have also been proposed (Japanese Unexamined Patent Publication No.
39399).

Since the N-vinylformamide and acrylonitrile copolymer are insoluble in water, the copolymer is obtained as a precipitate by polymerization in an aqueous medium, so that the copolymer is separated and recovered after polymerization. It is considered to be easy to handle such as transfer to a hydrolysis step, and is desirable in industrial operation. However, the water-insoluble copolymer particles produced during the polymerization are coalesced by the particles, or the vessel walls of the polymerization vessel,
There is a disadvantage that it adheres to a stirrer or the like and agglomerates. In particular, in the case of a low molecular weight copolymer, the tendency is remarkable. Therefore, a method of polymerizing N-vinylformamide using a polymer dispersant dissolved in an organic solvent has been proposed (JP-A-6-122725).

[0005] However, this method cannot be carried out efficiently, for example, because an operation of separating an organic solvent is required when the obtained polymer is hydrolyzed. Therefore, the copolymer does not agglomerate in the aqueous medium, and the vessel walls of the polymerization vessel,
There has been a strong demand for the development of a method for producing an N-vinylformamide copolymer or the like that can be handled in a fluid state without adhering to a stirrer or the like.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to handle a copolymer in an aqueous medium in a fluidized state without agglomeration and without adhering to the vessel walls of a polymerization vessel, a stirrer, or the like. For producing a dispersion in which water-insoluble polymer particles such as N-vinylformamide copolymer are dispersed, a method for purifying polymer particles for separating polymer particles from the dispersion, and a method for dissolving water-insoluble polymer particles in a water-soluble or water-swellable polymer To provide a method for modifying a polymer.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies on a method for preventing agglomeration of copolymer particles formed in a method of copolymerizing N-vinylformamide and acrylonitrile in an aqueous medium. by performing the copolymerization in the presence of a particle size control agent comprising a water-soluble inorganic halide compound, agglomeration of the copolymer is suppressed, that the copolymer can be treated as a colloidal dispersion or slurry The present invention has been completed.

According to the first aspect of the present invention, a monomer mixture containing N-vinylcarboxylic acid amide and acrylonitrile is polymerized with a monomer aqueous solution having a weight ratio of water of 0.05 to 0.3: 1. in obtaining a dispersion of insoluble polymer particles, a method for producing a polymer particle dispersion, characterized by using a particle size modifier consisting of water-soluble inorganic halide compound.

According to a second aspect of the present invention, in the method for producing a polymer particle dispersion according to the first aspect, the N-vinylcarboxylic acid amide is N-vinylformamide.

According to a third aspect of the present invention, there is provided the method for producing a polymer particle dispersion according to the first aspect, wherein the weight ratio of the water-soluble inorganic halide to water is 0.05 to 0.1.
5: 1.

According to a fourth aspect of the present invention, there is provided the method for producing a polymer particle dispersion according to the third aspect, wherein the water-soluble inorganic halide is sodium chloride, calcium chloride, ammonium chloride, potassium bromide, or a mixture thereof. It is one selected from a mixture.

According to a fifth aspect of the present invention, in the method for producing a polymer particle dispersion according to the third aspect, the water-soluble inorganic halide is sodium chloride.

The invention of claim 6 of the present invention provides the method of claim 1 to claim 5.
Wherein the average particle diameter of the obtained water-insoluble polymer particles is 1 to 5000 microns.

[0014] The invention of claim 7 of the present invention is directed to claims 1 to 6.
In the method for producing a polymer particle dispersion according to the above,
The vinyl carboxylic acid amide and acrylonitrile have a molar ratio in the range of 35:65 to 55:45.

[0015] The invention of claim 8 of the present invention relates to claims 1 to 7.
The method for purifying polymer particles comprises performing an operation of separating the polymer particle dispersion obtained by the production method described in 1) into polymer particles and a dispersion medium.

The ninth aspect of the present invention provides the first to seventh aspects.
The method for purifying polymer particles comprises separating the polymer particle dispersion obtained by the production method described in 1 above into polymer particles and a dispersion medium, and then washing the polymer particles with water.

The invention of claim 10 of the present invention provides the method of claim 1
7. A method for modifying a polymer, characterized in that a water-insoluble polymer dispersion obtained by the production method described in 7 is hydrolyzed with an acid or an alkali to obtain a water-soluble or water-swellable polymer.

The invention of claim 11 of the present invention is directed to claims 8 to
A method for modifying a polymer, characterized in that water-insoluble polymer particles obtained by the purification method described in 9 are hydrolyzed with an acid or an alkali to obtain a water-soluble or water-swellable polymer.

The invention of claim 12 of the present invention is the invention of claim 10
The method for modifying a polymer according to any one of Items 1 to 11 , wherein the hydrolysis is performed with hydrochloric acid.

Hereinafter, the present invention will be described in detail. Specifically, the present invention specifically provides, for example, a polymerization reaction of a mixture of N-vinylformamide and acrylonitrile in an aqueous medium by radical polymerization, and forming a water-insoluble polymer (hereinafter, referred to as a copolymer) into a colloidal dispersion or a slurry. It is a method to get as. The average particle size of the water-insoluble copolymer particles is not particularly limited, but is preferably in the range of usually about 1 to 5000 microns for good workability. Any known polymerization method can be used as the polymerization method. Specifically, for example, the mixed monomer can be polymerized in an aqueous medium with stirring using a radical polymerization initiator.

In this case, the weight ratio of the monomer mixture containing N-vinylformamide and acrylonitrile to water is 0.05 to 0.3: 1. If the weight ratio of the monomer mixture and water is 0.3: 1 or more, stirring becomes difficult, and
When the ratio is not more than 05: 1, the production efficiency decreases, which is not preferable. The molar ratio of N-vinylformamide to acrylonitrile is from 5:95 to 55:45, preferably from 35:65.
55:45 is used. The monomer concentration is 5 to 3
0% by weight, preferably 5 to 20% by weight.

Examples of the radical polymerization initiator include, for example, 2,
2'-azobis-2-amidinopropane dihydrochloride, 4,
4'-azobis-4-cyanovaleric acid sodium salt, 2,
Azo initiators such as 2'-azobis-N, N'-dimethyleneisobutylamidine dihydrochloride are preferred. Further, these polymerization initiators may be used in combination with other oxidizing and / or reducing initiators. The amount of the polymerization initiator used is usually 100 to 10000 ppm based on the monomer.
It is about.

Examples of the chain transfer agent for reducing the molecular weight include alcohols such as methanol, ethanol and 2-propanol, and sulfur-containing compounds such as mercaptoethanol. The amount used is 0.1 to 200% by weight for alcohols and 0.01 to 10% by weight for mercaptoethanol based on the monomer.

As the aqueous medium, water alone is preferable.
An organic solvent that is uniformly mixed with water, for example, dimethyl sulfoxide, methanol, N-methylpyrrolidone, or the like may be mixed with water.

Examples of the water-soluble inorganic halide which is one of the particle size adjusting agents used in the copolymerization of the present invention include, for example, sodium chloride, potassium chloride, magnesium chloride, calcium chloride, barium chloride, ammonium chloride, bromide. Examples thereof include chlorides and / or bromides such as alkali metals such as sodium and potassium bromide, alkaline earth metals, and ammonium. These water-soluble inorganic halides are used in an amount of at least 2% by weight, preferably at least 5% by weight, based on the aqueous medium. If the content is less than 2% by weight, the copolymer particles formed during the polymerization tend to be coalesced into a lump. A saturated aqueous solution of a water-soluble inorganic halide is also used, and two or more water-soluble inorganic halides can be used in combination.

The polymerization temperature is usually 30 to 100 ° C.,
The polymerization time is about 0.5 to 20 hours. As the polymerization method, there is a method in which the entire amount of the monomer is charged into a polymerization vessel in advance and the polymerization is started, or a method in which a part of the monomer is charged in the polymerization vessel and the polymerization is started, and the remaining monomer is charged as the polymerization proceeds. Adopted.

Usually, the copolymer of N-vinylformamide and acrylonitrile precipitates out of an aqueous medium as a precipitate, and coarse particles or particles are coalesced together, or the wall of a polymerization vessel, a stirrer, or the like. The copolymer obtained by the method of the present invention has fine particles in the form of a colloidal dispersion or a slurry, and is dispersed in an aqueous medium. There is no adhesion to the vessel wall and the stirrer. This is because the amount of particle size modifier copolymer particles because the particle size is affected, growth of the particles of the copolymer by the particle size control agent dissolved is inhibited during the polymerization, the very fine particles It is presumed to be deposited at the stage, but is not limited to this reason.

In the present invention, the obtained dispersion can be hydrolyzed with an acid or an alkali. However, after the copolymer particles are separated from the dispersion, the dispersion can be hydrolyzed with an acid or an alkali. After separating the copolymer particles, impurities may be removed by washing the copolymer particles with water, followed by a hydrolysis reaction. After separating the copolymer particles from the dispersion, the impurities are removed by washing the copolymer particles with water, and then performing a hydrolysis reaction, thereby reducing the amount of a side reaction inhibitor used in the hydrolysis reaction. be able to.

As described above, since the copolymer obtained by the method of the present invention is in the form of a colloidal dispersion or a slurry in which uniform fine particles are dispersed, it is easily hydrolyzed under acidic conditions and becomes water-soluble. It becomes a vinylamine copolymer and exhibits excellent effects as a drainage improver, a filler retention improver, a sizing agent fixing agent, and a paper strength enhancer as a cationic polymer for the papermaking industry. Moreover, it is excellent as a flocculant for organic suspension and a dehydrating agent for organic sludge as a cationic flocculant for wastewater treatment.

[0030]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

(Example 1) 300 equipped with a stirrer, a nitrogen introducing pipe, a cooling pipe and a thermometer
27 g of sodium chloride and 150 g of distilled water were put into a four-necked four-neck flask. Then N-vinylformamide 1
1.4 g and acrylonitrile 8.6 g were added. After passing nitrogen gas under ice cooling to prevent acrylonitrile from evaporating, the temperature was raised to 50 ° C., and 3.0 g of a 2% by weight aqueous solution of 2,2′-azobis-2-amidinopropane dihydrochloride was added (the above monomer Was maintained at 50 ° C. with stirring for 6 hours. A dispersion in which a finely divided copolymer was precipitated in water was obtained. The sodium chloride in this case is a 15% by weight aqueous solution. A portion of the dispersion was taken, the copolymer particles were centrifuged, washed with acetone, dried at 50 ° C. under reduced pressure, and the reduced viscosity was measured. Further, the amount of the remaining monomer was measured by liquid chromatography analysis to determine the degree of polymerization. As a result, the average particle size of the copolymer particles was 400 to 500 microns, the conversion was 99.3%, and the reduced viscosity of the copolymer was 1
1.0. No adhesion of the copolymer to the vessel wall or the stirrer was observed.

The test method is shown below. (Liquid Chromatographic Analysis) Liquid chromatographic analysis was carried out under the following conditions by preliminarily filtering a precipitate containing a monomer through a 0.45 μm membrane filter. Column: Shodex RS Pak DM-61
4 _{Eluent: 0.1% - (NH 4)} 2 SO 4: methanol = 80: 20 (volume ratio) Flow rate: 0.5 ml / min UV wavelength: 200 nm Temperature: room temperature

(Measurement of Reduced Viscosity) A solid polymer was added to dimethyl sulfoxide at 0.1 g / d.
1 and dissolved at 25 ° C. using an Ostwald viscometer. Reduced viscosity [dl / g] = (t-to) /to/0.1 to: Falling time of dimethyl sulfoxide t: Falling time of polymer solution

(Examples 2 to 4) Polymerization was carried out using the same apparatus and method as in Example 1 using the concentrations of sodium chloride shown in Table 1. No polymer adhered to the vessel wall or the stirrer. Table 1 summarizes the results of the test performed in the same manner as in Example 1.

Comparative Example 1 Polymerization was carried out using the same apparatus and method as in Example 1 without using sodium chloride. Table 1 summarizes the results of the test performed in the same manner as in Example 1. The obtained copolymer became lump, and adhesion of the polymer to the vessel wall and the stirrer was observed.

[0036]

[Table 1]

As can be seen from Examples 2 to 4, as the sodium chloride concentration increased, the reduced viscosity of the copolymer increased.

(Examples 5 to 7) The same apparatus and method as in Example 1 were used, the monomer concentration was changed from 10% by weight to 5% by weight, and instead of sodium chloride, Example 5 was replaced with ammonium chloride. Polymerization was carried out in the same manner as in Example 1 except that calcium chloride was used in Example 6 and potassium bromide in Example 7 was used at the salt concentration shown in Table 2. Table 2 summarizes the results of the test performed in the same manner as in Example 1. No polymer adhered to the vessel wall or the stirrer.

(Comparative Examples 2 to 4) The same apparatus and method as in Example 1 were used, the monomer concentration was changed from 10% by weight to 5% by weight, and instead of sodium chloride, sodium sulfate was used in Comparative Examples 2 and 3. In Comparative Example 4, polymerization was carried out in the same manner as in Example 1 except that sodium acetate was used at the salt concentration shown in Table 2. Table 2 summarizes the results of the test performed in the same manner as in Example 1. The obtained copolymer became lump, and adhesion of the polymer to the vessel wall and the stirrer was observed.

[0040]

[Table 2]

Example 8 The same apparatus and method as in Example 1 were used to obtain N-monomer as a monomer.
Polymerization was carried out in the same manner as in Example 1 except that 10.46 g of vinylformamide and 9.54 g of acrylonitrile were used, and a 20% by weight aqueous solution of sodium chloride was used as an aqueous medium. As a result, the average particle size of the copolymer was 20
-40 microns, the polymerization rate was 98.7%, and the reduced viscosity of the copolymer was 8.7.

Example 9 The same apparatus and method as in Example 1 were used as a chain transfer agent.
Polymerization was carried out in the same manner as in Example 1 except that 2.0 g of a 10% by weight aqueous solution of mercaptoethanol was added and a 10% by weight aqueous solution of sodium chloride was used. As a result, a copolymer having a reduced viscosity of 1.6 was obtained in the form of a slurry.

(Example 10) The copolymer of Example 1 was washed with water and filtered, and then, in the presence of hydroxylamine hydrochloride, 1 to the formamide group in the copolymer.
An equivalent amount of 35% hydrochloric acid was added, and the mixture was maintained at 70 ° C. for 6 hours for hydrolysis to obtain a water-soluble vinylamine copolymer. The reduced viscosity of a 0.1% solution of this product in a 1N aqueous solution of sodium chloride was 2.0, and the cation equivalent value by colloid titration measured at pH 3 was 5.3 meq / g.

(Measurement of Colloid Equivalent Value) A solid polymer was dissolved in distilled water to a concentration of 0.1% by weight. After adjusting 5.0 g of this aqueous solution to pH 3, １ ／
It was determined by colloid titration using toluidine blue as an indicator using 00N potassium polyvinyl sulfate.

[0045]

According to the present invention, as described above, the agglomeration of the copolymer is suppressed, and the copolymer does not adhere to the vessel wall of the polymerization vessel, the stirrer, etc., and the copolymer can be a colloidal dispersion or a liquid. It can be handled as a slurry.

Since the water-insoluble copolymer obtained by the method of the present invention is in the form of a colloidal dispersion or a slurry in which uniform fine particles are dispersed, it is easily hydrolyzed under acidic conditions to form a water-soluble vinylamine. It can be a copolymer.

After separating the water-insoluble copolymer particles from the dispersion obtained by the method of the present invention, the copolymer particles are washed with water to remove impurities and then subjected to a hydrolysis reaction. The amount of the side reaction inhibitor used in the hydrolysis reaction can be reduced.

The obtained water-soluble vinylamine copolymer is a cationic polymer for the papermaking industry and has excellent effects as a drainage improver, a filler retention improver, a fixing agent for a sizing agent, a paper strength enhancer, and the like. It is also excellent as a flocculant for organic suspensions as a cationic flocculant for wastewater treatment and as a dehydrating agent for organic sludge, so that it has high industrial utility value.

Claims (12)

(57) [Claims] 1. A dispersion of water-insoluble polymer particles is obtained by polymerizing a monomer mixture containing N-vinylcarboxylic acid amide and acrylonitrile and an aqueous monomer solution having a weight ratio of water of 0.05 to 0.3: 1. per the method for producing a polymer particle dispersion, characterized by using a particle size adjusting agent comprising a water-soluble inorganic halide compound or al. 2. The method for producing a polymer particle dispersion according to claim 1, wherein the N-vinyl carboxylic acid amide is N-vinyl formamide. 3. The method for producing a polymer particle dispersion according to claim 1, wherein the weight ratio of the water-soluble inorganic halide to water is 0.05 to 0.5: 1. 4. The polymer particles according to claim 3, wherein the water-soluble inorganic halide is one selected from sodium chloride, calcium chloride, ammonium chloride, potassium bromide and a mixture thereof. A method for producing a dispersion. 5. The method for producing a polymer particle dispersion according to claim 3, wherein the water-soluble inorganic halide is sodium chloride. 6. The resulting method of manufacturing a polymer particle dispersion liquid according to claim 1-5 where the average particle size of the water-insoluble polymer particles characterized in that 1 to 5000 microns. 7. N- vinylcarboxamide and the molar ratio of acrylonitrile 35: 65-55: method for producing a polymer particle dispersion liquid according to claim 1-6, characterized in that in the range of 45. 8. claims 1-7 purification process of the polymer particles, characterized in that to operate the polymer particle dispersion obtained by the process for the preparation according to separate the polymer particles and the dispersion medium. 9. After the claims 1-7 polymer particle dispersion obtained by the production method described in separated into the polymer particles and the dispersion medium, purification of the polymer particles, which comprises washing the polymer particles Method. 10. A polymer characterized by obtaining a claim 1-7 hydrolyzed to water-soluble or water-swellable polymer with an acid or an alkali and the resulting water-insoluble polymer dispersion by the production method described in Denaturation method. 11. Modification of a polymer characterized in that a water-insoluble polymer particle obtained by the purification method according to claim 8 or 9 is hydrolyzed with an acid or an alkali to obtain a water-soluble or water-swellable polymer. Method. 12. The method for modifying a polymer according to claim 10 , wherein the hydrolysis is carried out with hydrochloric acid.