JPH0665366B2 - Flocculant made of vinylamine copolymer - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a flocculant comprising a vinylamine copolymer.

[0002]

2. Description of the Related Art Polyvinylamine has hitherto been treated with poly N- by the Hofmann decomposition of polyacramide.
A method of producing vinylamide by hydrolysis is known. In particular, the method of hydrolyzing a homopolymer of N-vinylformamide is an excellent method capable of synthesizing polyvinylamine having a high molecular weight and good stability. However, the obtained polymer had extremely high hydrophilicity, and the effect when used as a flocculating agent for dehydration was insufficient. A method is known in which N-vinylformamide and ethylene are preliminarily copolymerized and hydrolyzed in order to impart hydrophobicity to polyvinylamine. However, N-vinylformamide and ethylene have poor copolymerizability. In addition, it was difficult to obtain a high molecular weight copolymer, and this objective could not be achieved by the copolymerization.

The present inventors have also previously provided an aggregating agent using a basic hydrolyzate of a copolymer of N-vinylformamide and N, N-dialkyl (meth) acrylamide (Japanese Patent Laid-Open No. Sho 61-206). 61-118406). However, this hydrolyzate becomes a quaternary copolymer containing a carboxyl group,
When used as a coagulant for dehydration, the water content of the dehydrated sludge could not be lowered sufficiently.

[0004]

The present invention comprises structural units represented by the following general formulas [I], [II] and [III],

[0005]

[Chemical 2] (In the formula, X represents an anion)

(In the formula, R ¹ represents a hydrogen atom or a methyl group, R ² represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ³ represents an alkyl group having 1 to 4 carbon atoms or 4 to 4 carbon atoms.
8 represents an oxoalkyl group of 8) The structural unit [I] has a mole fraction of 5 to 85 mol%, the structural unit [II] has a mole fraction of 5 to 85 mol%, and the structural unit [III]
Relates to a flocculant composed of a vinylamine copolymer having a molar fraction of 90 to 5 mol%.

The preferred composition of the vinylamine copolymer of the present invention is such that the structural unit [I] has a mole fraction of 5 to 85 mol%, the structural unit [II] has a mole fraction of 5 to 85 mol%, The molar fraction of [III] is in the range of 60 to 10 mol%, and particularly preferable composition is that the structural unit [I] has a molar fraction of 5 to 85 mol%, and the structural unit [II] has a molar fraction of 5 to 85 mol%, the molar fraction of the structural unit [III] is 40 to
It is in the range of 10 mol%.

The vinylamine copolymer of the present invention is usually
It is a water-soluble polymer having a reduced viscosity value of 0.1 to 10 dl / g, preferably 1 to 10 dl / g, measured at 25 ° C. as a solution of 0.1 g / dl in 1N saline. The vinylamine copolymer of the present invention can be easily obtained by modifying the formyl group in the following N-vinylformamide copolymer under acidic conditions. The N-vinylformamide copolymer as a raw material is N-vinylformamide,
The following general formula [I
V)

[0009]

[Chemical 3] The molar ratio of the compound is usually 10:90 to 95: 5, preferably 40:60 to 95: 5, more preferably 60:40 to 90:10 in the presence of a radical polymerization initiator. It is a copolymer obtained by lower polymerization.

Examples of the N-substituted acrylamide or N-substituted methacrylamide of the general formula [IV] are those in which R ¹ is a hydrogen atom or a methyl group, R ² is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R is ^A compound in which ³ is an alkyl group having 1 to 4 carbon atoms or an oxoalkyl group having 4 to 8 carbon atoms is used. For example, N-methylacrylamide, N-
Ethyl acrylamide, Nn-propyl acrylamide, N-isopropyl acrylamide, Nn-butyl acrylamide, N-isobutyl acrylamide, N-
t-butyl acrylamide, N, N-dimethyl acrylamide, N, N-diethyl acrylamide, N, N-di-n-propyl acrylamide, N, N-di-n-butyl acrylamide, N- (1,1-dimethyl- 3-oxobutyl) acrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, Nn-propylmethacrylamide, N-isopropylmethacrylamide,
N-n-butyl methacrylamide, N-isobutyl methacrylamide, Nt-butyl methacrylamide, N,
N-dimethyl methacrylamide, N, N-diethyl methacrylamide, N, N-di-n-propyl methacrylamide, N, N-di-n-butyl methacrylamide, N-
(1,1-dimethyl-3-oxobutyl) methacrylamide and the like can be mentioned. Particularly preferred are N-isopropylacrylamide, Nt-butylacrylamide,
These are N, N-dimethylacrylamide and N- (1,1-dimethyl-3-oxobutyl) acrylamide.

As the polymerization method for producing the above N-vinylformamide copolymer, any of bulk polymerization, precipitation polymerization and solution polymerization can be used, but the solution polymerization method is preferable, and the aqueous solution polymerization is particularly preferable. It's legal. When using the aqueous solution polymerization method, the molecular weight of the target polymer,
The concentration of the monomer, the polymerization method, and the shape of the polymerization reactor are appropriately selected in consideration of the heat of polymerization, and for example, the polymerization is performed by the following method. That is, the monomer concentration is 5 to 20.
Method of polymerizing in solution under the condition of weight%, monomer concentration 20
A method of polymerizing in a hydrogel state under the condition of ˜60% by weight, an aqueous solution having a monomer concentration of 20 to 60% by weight is polymerized in an oil-in-water or water-in-oil emulsion state using a hydrophobic solvent and an emulsifier Examples of the method include a method of polymerizing an aqueous solution having a monomer concentration of 20 to 60% by weight in a dispersed state of water in oil using a hydrophobic solvent and a dispersion stabilizer.

As the radical polymerization initiator, any of the general initiators usually used for the polymerization of water-soluble or hydrophilic monomers is used, but in order to obtain a polymer in good yield, Azo compounds are preferred. Especially preferred are water-soluble azo compounds, examples of which are 2,2'-
Examples include azobis-2-amidinopropane hydrochloride and acetate, sodium salt of 4,4′-azobis-4-cyanovaleric acid, azobis-N, N′-dimethyleneisobutylamidine hydrochloride and sulfate. The amount of these polymerization initiators to be used is generally 0.01 to the weight of the monomer.
It is in the range of 1% by weight. The polymerization reaction is generally carried out at a temperature of 30 to 100 ° C under an inert gas stream.

The resulting N-vinylformamide copolymer is novel as it is or after diluting in the form of a solution, or by dehydration or drying by a known method to obtain a powder and then denaturing under acidic conditions. It can be polyvinylamine. Examples of the modification method used in that case include a method of acidic hydrolysis in water, a method of acidic hydrolysis in a hydrophilic solvent such as alcohol containing water, a method of alcoholysis under acidic conditions, and the like. However, the preferred method is to modify the formyl group while separating it as a formate ester. By these methods, the modification reaction of the structural unit represented by the general formula [III] is suppressed, and a vinylamine copolymer containing substantially no carboxyl group is produced. As the modifier used in the case of acidic modification, any compound that acts on strong acidity can be used, and examples thereof include hydrochloric acid, bromic acid, hydrofluoric acid, sulfuric acid, nitric acid and phosphoric acid. , Sulfamic acid, alkanesulfonic acid and the like. The amount of the modifier used is usually in the range of 0.1 to 2 times by mole with respect to the formyl group in the polymer, and is appropriately selected according to the target modification ratio. Further, as the alcohol used in the case of alcoholysis,
An alcohol having 1 to 4 carbon atoms can be mentioned, but methanol is preferable.

The vinylamine copolymer flocculant of the present invention exhibits excellent effects such as a cationic flocculant for treating wastewater for flocculation of an organic suspension and a flocculant for dehydration of organic sludge. To do. In particular, it exhibits excellent effects as a primary flocculation sludge in sewage treatment, activated sludge treatment of water-soluble organic matter, sludge generated in anaerobic treatment, and a flocculating agent for dehydration of these mixtures. The method of use is the same as that of a conventionally known cationic flocculant, for example, a quaternized polymer of dimethylaminoethyl methacrylate. That is, it is usually 20 to 20,000 with respect to a suspension containing organic sludge in the form of an aqueous solution of 0.1 to 0.5% by weight.
It is added and mixed in a weight range of ppm.

The organic sludge coagulated with the coagulant of the present invention forms stronger cohesive flocs than when a polymer obtained by modifying a homopolymer of N-vinylformamide is used. By performing squeezing dewatering such as Vect press, screw press, filter press, or mechanical dewatering such as centrifugation, vacuum filtration, etc., the dewatering treatment speed is increased, the treatment amount is increased, and the water content of the dewatered sludge is reduced. .

[0016]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

(Production of Vinylamine Copolymer) Production Example 1 In a 200 ml four-necked flask equipped with a stirrer, a nitrogen introducing tube and a cooling tube, 8.76 g of N- (1,1-dimethyl-
3-Oxobutyl) acrylamide and 29.8 g of demineralized water were added. After the temperature was raised to 60 ° C. with stirring in a nitrogen gas stream, 0.2 g of a 10 wt% 2,2′-azobis-2-amidinopropane dihydrochloride aqueous solution was added. The stirring was stopped and the mixture was kept at 50 ° C. for 5 hours. After 1 g of the obtained hydrous gel was dehydrated and precipitated in 20 ml of acetone, the precipitate was vacuum dried to obtain a solid polymer. The residual monomer in acetone used for dehydration was analyzed by liquid chromatography to measure the polymerization rate. The results are shown in Table-1.

The water-containing gel of the obtained polymer has a particle size of about 0.5.
It was crushed to a size of mm and 10 g thereof was put together with 20 g of methanol into a reactor equipped with a 50 ml stirrer and a cooling tube. While stirring, 2.6 g of 35 wt% hydrochloric acid was added, and the mixture was reacted under heating under reflux for 4 to 6 hours. The product was dehydrated with acetone and then vacuum dried. The reduced viscosity and modification ratio (composition of modified product) of the obtained powdery water-soluble polymer (hereinafter referred to as polymer A) were measured by the methods described below. The results are shown in Table-2.

(Measurement of Reduced Viscosity) The solid polymer was dissolved in 1N saline to a concentration of 0.1 g / dl, and the reduced viscosity at 25 ° C. was measured using an Ostwald viscometer.

[0020]

## EQU1 ## Reduced viscosity [dl / g] = [(t−t ₀ ) / t ₀ ] /0.1 t ₀ : descent time of saline solution t: descent time of polymer solution

(Measurement of modification ratio) A solid polymer was added to 0.1
It was dissolved in distilled water at a concentration of wt%. 5.0 g of this aqueous solution
Was diluted to 200 ml with demineralized water, the pH of the solution was adjusted to 3 with dilute hydrochloric acid, and then obtained by a colloid titration method using toluidine blue as an indicator using 1/400 N potassium polyvinyl sulfate. The modification ratio of the formyl group was calculated from the equivalent amount of the cation group.

Production Examples 2 to 7 Instead of N- (1,1-dimethyl-3-oxobutyl) acrylamide of Production Example 1, comonomers of the types and mole fractions shown in Table 1 were used, and the same is shown in Table 1. After polymerizing at a monomer concentration, the polymer was modified in the same manner as in Example 1 to obtain a water-soluble polymer. The polymerization rates (hereinafter, referred to as polymers B to G, respectively) are shown in Table 1. Further, the results of measuring the reduced viscosity and the modification rate (the composition of the modified product) using the obtained water-soluble polymer in the same manner as in Production Example 1 are shown in Table 1.

[0023]

[Table 1] Note) DAAM: N- (1,1-dimethyl-3-oxobutyl) acrylamide DMAM; N, N-dimethylacrylamide IPAM: N-isopropylacrylamide

[0024]

[Table 2] Note) Structural unit [III] is the structural unit of the polymer of each raw material monomer in Table 1.

(Aggregating Performance) Examples 1 to 7 and Comparative Examples 1 to 3 A raw sewage treatment plant mixed raw sludge (solid content: 2.0% by weight) 10
Put 0 ml into a 200 ml polyethylene beaker,
5 ml of the polymers A to G produced in the above Production Example and the polymers H to J shown in Table 3 were added in the form of a 0.2 wt% aqueous solution. Using a stirring rod having three round bars each having a diameter of 5 mm and a length of 20 mm, the stirring was performed at a speed of 1000 rpm for 10 seconds. The coagulated sludge was placed in a cylinder having a 60-mesh nylon screen with a diameter of 65 mm at the bottom, and the sludge was filtered by gravity filtration, and the amount of filtrate after 10 seconds was measured. Further, the sludge after gravity filtration is put in a centrifugal basket having a draining net at the bottom,
Centrifugal dehydration was performed for 30 seconds at a rotation speed of 00 rpm. The sludge after dehydration was dried at 110 ° C. for 6 hours to measure the solid content, and the water content of the sludge after centrifugal dehydration was calculated. The results are shown in Table-3.

[0026]

[Table 3] 1) Polymer H: poly-2-methacryloyloxyethyl trimethyl ammonium chloride (reduced viscosity 4.5d
1 / g) 2) Polymer I: N-vinylformamide-ethylene (molar ratio; 56/44) copolymer hydrolyzate (modification rate 59
Mol%, reduced viscosity 0.2 dl / g) 3) Polymer J: Product obtained by basic hydrolysis of N-vinylformamide copolymer of Production Example 6 in water (modification rate 68 mol%).

[0027]

The flocculant comprising the vinylamine copolymer of the present invention exhibits excellent effects as a cationic flocculant for treating wastewater and as a flocculating agent for dehydrating organic sludge. In particular, it exhibits excellent effects as a primary flocculation sludge in sewage treatment, activated sludge treatment of water-soluble organic matter, sludge generated in anaerobic treatment, and a flocculating agent for dehydration of these mixtures.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Koichi Sato Inventor, Koichi Sato 1000 Kamoshida-cho, Midori-ku, Yokohama, Kanagawa Sanryo Kasei Co., Ltd. (56) Reference JP-A-59-39399 (JP, A) JP S58-23809 (JP, A) JP-A-59-39400 (JP, A)

Claims (1)

[Claims] 1. The following general formulas [I], [II] and [III]
] The structural unit represented by (In the formula, X represents an anion) (In the formula, R ¹ represents a hydrogen atom or a methyl group, R ² is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ³ is an alkyl group having 1 to 4 carbon atoms or an oxoalkyl having 4 to 8 carbon atoms. Representing a group) The structural unit [I] has a mole fraction of 5 to 85 mol%, the structural unit [II] has a mole fraction of 5 to 85 mol%, and the structural unit [III]
Is a coagulant composed of a vinylamine copolymer having a molar fraction of 90 to 5 mol%.