JPH07136410A - Sludge deposition preventing agent - Google Patents

Abstract

PURPOSE:To provide a sludge deposition preventing agent with which an inorganic substance and slime particles are efficiently prevented from growing and flocculating and which is safe and easy to handle by containing a specified unsaturated carboxylic acid polymer and a specified nitrogen-containing compound. CONSTITUTION:A sludge deposition preventing agent contains a homopolymer, copolymer, or their salts together with a compound selected from benzoisothiazolon, lower alkyl-substituted benzoisothiazolon, and bromonitro- alcohol-type compounds wherein the homopolymer and the copolymer contain an unsaturated carbonic acid monomer selected from acrylic acid monomer unit, methacrylic acid monomer unit, and maleic acid monomer unit.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel sludge deposition inhibitor, and more particularly to a sludge deposition inhibitor capable of effectively preventing the growth and aggregation of inorganic substances such as scale, earth and sand, corrosion products and slime particles in water. It is related to agents.

[0002]

2. Description of the Related Art Conventionally, cooling water used for cooling factory facilities and products, or industrial water used for controlling temperature and humidity is collected from river water or groundwater and supplied after being purified. ing. Since such water contains hardness components, iron, suspended matter, microorganisms, etc., sludge, which is often composed of inorganic particles such as scale and slime (microorganisms), often forms pits, heat exchanger partition chambers, shell side heat. Low flow velocity parts such as exchangers (especially when the flow velocity of water is
(3 m / sec or less), which may cause a decrease in water supply capacity and thermal efficiency. In particular, in recent years, in the open-circulation cooling water system that is becoming popular due to the shortage of industrial water, with the high concentration of the hardness component and the like, corrosion products in the destination of the cooling water, oil, soil and the like, and, The adverse effect of sludge accumulation due to the growth of microorganisms that use these contaminants as nutrients has become a serious problem. The mechanism of such sludge deposition in cooling water differs depending on the water quality, and the details are not clear, but the growth and aggregation of inorganic particles such as scale, sediment, and corrosion products, and the growth and aggregation of microorganisms Progress at the same time, the fine suspended matter gradually grows, and slime (microorganism)
It is considered that the suspended matter is coarsened due to inclusion of the above-mentioned inorganic particles by the viscous substance (bioflocculation) and the like and is accumulated as sludge. Therefore, in order to prevent the accumulation of sludge, at least it is necessary to prevent both the aggregation of inorganic particles and the aggregation of slime. Therefore, for such a purpose, one kind of unsaturated carboxylic acid selected from acrylic acid, methacrylic acid and maleic acid, a salt thereof or maleic anhydride, and an unsaturated alcohol are used as a sludge deposition inhibitor. A copolymer with an unsaturated carboxylic acid ester and one nonionic unsaturated compound selected from alkenes, and monomethylhydrazine, phenylhydrazine, hydrazine maleate,
A compound containing at least one nitrogen-containing compound selected from 5-chloro-2-isothiazolin-3-one, hydroxylamine and hydroxylamine salt has been proposed (Japanese Patent Publication No. 61-27361). ). However, although the above-mentioned sludge deposition inhibitor has a good sludge deposition prevention effect, the hydrazine compound used in the deposition inhibitor is concerned about safety, and 5-chloro-2-isothiazolin-3-one Has significant skin irritation and hydroxylamine is a deleterious substance, and thus has safety and hygiene and handling problems.

[0003]

Under the circumstances described above, the present invention is capable of efficiently preventing the growth and aggregation of inorganic substances such as scale, earth and sand, corrosion products, etc. and slime particles in water, and The purpose of the present invention is to provide a sludge accumulation inhibitor that does not cause any problems in terms of safety and health or handling.

[0004]

The inventors of the present invention have conducted extensive studies to develop a sludge deposition inhibitor having the above-mentioned preferable properties, and as a result, a specific unsaturated carboxylic acid polymer and a specific nitrogen-containing compound have been obtained. It has been found that those containing and can meet the purpose, and the present invention has been completed based on this finding. That is, the present invention relates to (A) a homopolymer, a copolymer or a salt thereof containing at least one unsaturated carboxylic acid unit selected from acrylic acid units, methacrylic acid units and maleic acid units. A sludge deposition inhibitor comprising at least one selected from the group consisting of (B) benzisothiazolone, its lower alkyl-substituted compound and at least one selected from bromonitroalcohol compounds. Is.

The present invention will be described in detail below. In the sludge deposition inhibitor of the present invention, an unsaturated carboxylic acid polymer is used as the component (A). This unsaturated carboxylic acid polymer is a homopolymer, a copolymer or a salt thereof containing at least one unsaturated carboxylic acid unit selected from acrylic acid units, methacrylic acid units and maleic acid units. Is. As the raw material monomer in the unsaturated carboxylic acid polymer, unsaturated carboxylic acids such as acrylic acid, methacrylic acid and maleic acid, salts of these unsaturated carboxylic acids, for example, alkali metal salts such as sodium salt and potassium salt, Mention may be made of maleic anhydride. These monomers may be polymerized alone, or two or more of them may be copolymerized, and one or more of these monomers and one or more of the other copolymerizable nonionic unsaturated compounds may be copolymerized. You may let me. As other copolymerizable nonionic unsaturated compounds, for example, unsaturated alcohols, unsaturated carboxylic acid esters, alkenes and the like can be used. Preferred examples of the unsaturated alcohol include those having 4 or less carbon atoms such as vinyl alcohol, allyl alcohol and 2-methylallyl alcohol, and examples of the unsaturated carboxylic acid ester include methyl acrylate and ethyl acrylate. Preferred are those having 6 or less carbon atoms such as hydroxyethyl acrylate and hydroxylethyl methacrylate. Further, examples of the alkene include isobutylene, n-butylene,
Preferable are those having 8 or less carbon atoms such as diisobutylene and pentene. These nonionic unsaturated compounds may be used alone or in combination of two or more.

The above-mentioned copolymer of unsaturated carboxylic acid and nonionic unsaturated compound is preferably water-soluble, and as a combination thereof, a copolymer of acrylic acid and allyl alcohol, maleic acid and isobutylene, in particular. Are preferable, copolymers of methacrylic acid and hydroxyethyl acrylate, and terpolymers of acrylic acid, hydroxyethyl methacrylate, and methyl acrylate. The content ratio of the unsaturated carboxylic acid unit and the nonionic unsaturated compound unit in these copolymers is preferably in the range of 99: 1 to 1:99 by molar ratio. Also, (A)
The molecular weight of the unsaturated carboxylic acid polymer used as a component is preferably in the range of 300 to 200,000. In the sludge deposition inhibitor of the present invention, the unsaturated carboxylic acid polymer as the component (A) may be used alone or in combination of two or more. On the other hand, in the sludge deposition inhibitor of the present invention, as the component (B), at least one nitrogen-containing compound selected from benzoisothiazolone, its lower alkyl-substituted compounds and bromonitroalcohol-based compounds is used. Examples of the benzisothiazolone and its lower alkyl-substituted compounds include those represented by the general formula [1]

[0007]

[Chemical 1]

(In the formula, R ¹ is a hydrogen atom or has 1 to 5 carbon atoms.
Which is an alkyl group of). Specific examples of the compound represented by the general formula [1] include 1,2-benzisothiazolin-3-one, 1,2
-Benzisothiazolin-2-methyl-3-one, 1,
2-benzisothiazolin-2-ethyl-3-one,
1,2-benzisothiazoline-2-isopropyl-3
-One, 1,2-benzisothiazolin-2-n-propyl-3-one, 1,2-benzisothiazolin-2-
Butyl-3-one, 1,2-benzisothiazoline-2
-Pentyl-3-one and the like can be mentioned, and these may be used alone or in combination of two or more.
To use these benzisothiazolones and their lower alkyl-substituted compounds in a liquid state, it is desirable to use an alkali metal hydroxide, preferably potassium hydroxide, so that the pH is 9 or higher. On the other hand, examples of the bromonitroalcohol-based compound include compounds represented by the general formula [2]

[0009]

[Chemical 2]

(R ² and R ³ in the formula are each 1 to 1 carbon atoms.
5 alkylene groups, which may be the same or different from each other). Specific examples of the bromonitro alcohol compound represented by the general formula [2] include 2-bromo-2-nitropropane-1,3-diol, 2-bromo-2-nitrobutane-1,4-diol, 2-Bromo-2-nitropentane-1,5-diol, 3-bromo-3-nitropentane-1,5-diol, 2-bromo-2-nitrohexane-1,6-diol, 3-bromo-3 -Nitrohexane-1,6-diol, 2-bromo-2-nitroheptane-1,7-diol, 3-bromo-3-nitroheptane-1,7-diol, 4-bromo-4-nitroheptane-1 , 7-diol and the like, and these are 1
One kind may be used, two or more kinds may be used in combination, and the benzisothiazolone and its lower alkyl-substituted compound may be used in combination. Further, the sludge deposition inhibitor using the bromonitroalcohol-based compound preferably has a pH of 5 or less for stabilization. Even nitrogen-containing compounds that exhibit a cationic property such as quaternary ammonium salts and guanidine may react with the unsaturated carboxylic acid-based polymer of the component (A) and prevent aggregation of slime. Since it has no action, it is not suitable as the component (B) in the present invention.

The mixing ratio of the unsaturated carboxylic acid polymer as the component (A) and the nitrogen-containing compound as the component (B) in the sludge deposition inhibitor of the present invention varies depending on the quality of water used, but the weight ratio is usually 1: It is selected in the range of 9 to 9: 1, preferably 3: 1 to 5: 1. In using the sludge deposition inhibitor of the present invention, if necessary, it is diluted with a solvent in advance, and then usually 0.5 ppm or more in water.
Preferably, 5-40 ppm continuous injection or intermittent injection may be performed. In addition, if necessary, a cooling water-based anticorrosive agent can be used in the sludge deposition inhibitor of the present invention. Examples of such an anticorrosive agent include orthophosphoric acid,
Examples thereof include polymerized phosphoric acid, condensed phosphoric acid and salts thereof, phosphonates, benzotriazole, tolyltriazole, mercaptobenzothiazole and the like. The unsaturated carboxylic acid polymer as the component (A) in the sludge deposition inhibitor of the present invention acts as a dispersant for inorganic particles in water and prevents its aggregation. On the other hand, the nitrogen-containing compound as the component (B) has a microbial growth inhibitory action, a bactericidal action, and a slime viscous substance denaturing action, and the action prevents slime aggregation. Further, since this compound does not exhibit a cationic property in water, it does not cause a reaction even when compounded with an anionic unsaturated carboxylic acid polymer, and does not cause it to gel. Since the sludge deposition inhibitor of the present invention has such characteristics, it can prevent aggregation of the inorganic particles and slime and aggregation due to interaction between the former and the latter. As a result, it has the effect of preventing the accumulation of sludge composed of coarse particles, especially in the low flow velocity part of the cooling water system, and its industrial value is extremely large.

[0012]

The present invention will be described in more detail by way of examples, which should not be construed as limiting the invention thereto. Examples 1 to 4 and Comparative Examples 1 to 9 Kaolin 10 pp having an average particle diameter of 10 μm as a viscosity component
m, 200ppm bacterial suspension (average particle size 3μm) consisting of sewage secondary treated water harvested culture as a microbial component, inorganic sludge collected from a certain plant's cooling water system (ignition loss 30wt
%, Average particle size 8 μm) 110 ppm, and ferric ion 5 ppm cooling water (pH 8.5, calcium hardness 250 pp)
(corresponding to 5 times concentrated water), and a test solution of a sludge accumulation inhibitor was prepared. The initial average particle size of the suspended particles in this test solution was 10 μm. Next, as shown in Table 1, a predetermined amount of the sludge deposition inhibitor of the present invention and a comparative additive therefor were added to the test solution at 30 ° C.,
After stirring at 300 rpm for 24 hours, the average particle size of the particles in water was determined using a centrifugal sedimentation type particle size distribution analyzer, and the multiple of the increase in the particle size from the initial average particle size (particle size multiple) was calculated. The molecular weights of the used polymaleic acid and hydroxyethyl acrylate-methacrylic acid copolymer were each 1.0
It was 00,4,500. Further, in the same manner, a blank test was conducted without adding the sludge deposition inhibitor and other various additives, and the particle size multiple was calculated. The results are shown in Table 1.

[0013]

[Table 1]

It is clear from Table 1 that the sludge deposition inhibitor of the present invention effectively prevents the aggregation of inorganic particles and slime particles more than the conventional inhibitors. On the other hand, even if each of the unsaturated carboxylic acid polymer and the nitrogen-containing compound was used alone, there was almost no effect in preventing the aggregation of the particles. Example 5, Comparative Examples 10 and 11 A sludge deposition test was conducted using a sludge monitor having a length of 120 cm, a height of 25 cm and a width of 20 cm. The same cooling water as in Examples 1 to 4 and Comparative Examples 1 to 9 was used.
Circulation was performed so that the flow rate was 0.06 to 0.1 m / sec in the monitor. In addition, in Example 5, 10 mg of polymaleic acid
/ L and 1,2-benzisothiazolin-3-one 10 mg / L were added to the circulating water, and this state was continued for 2 weeks. In Comparative Example 10, polymaleic acid 1
0 mg / l and 5-chloro-2-isothiazoline-
3-one 10 mg / liter was added to the circulating water, and this state was continued for 2 weeks. Further, in Comparative Example 11, a state in which nothing was added as a blank was continued for 2 weeks. The results are shown in Table 2.

[0015]

[Table 2]

As is clear from Table 2, the sludge deposition inhibitor of the present invention can prevent sludge deposition in the low flow velocity portion. Example 5 has a smaller amount of sludge accumulation than Comparative Example 10 and is excellent in the effect of preventing sludge accumulation, while 5-chloro-2-isothiazolin-3-one is easily decomposed in water. It is considered that 1,2-benzisothiazolin-3-one is stable in water and maintains its effect for a long time.

[0017]

INDUSTRIAL APPLICABILITY The sludge deposition inhibitor of the present invention can efficiently prevent the growth and aggregation of inorganic substances such as scale, earth and sand, corrosion products and slime particles in water, and also has problems in safety and hygiene and handling. It has features such as no

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Claims (1)

[Claims] 1. A homopolymer, a copolymer or a salt thereof containing (A) at least one unsaturated carboxylic acid unit selected from acrylic acid units, methacrylic acid units and maleic acid units. At least one selected from
(B) A sludge deposition inhibitor comprising benzisothiazolone, a lower alkyl-substituted compound thereof and at least one selected from bromonitroalcohol compounds.