JPH0465803B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to a water system damage prevention agent containing a chlorine agent, and more particularly to an agent for preventing corrosion of open or closed water systems and the formation of slime in the water system. In recent years, with the increasing demand for industrial water, it has become common practice to use recycled water at unprecedentedly high circulation rates and to reuse treated industrial wastewater and sewage water. However, the utilization of such circulating water or treated water has been accompanied by problems such as corrosion problems and slime problems in the water system. This corrosion damage is caused by dissolved salts such as dissolved oxygen, chloride ions, and sulfate ions in the water, and slime damage is caused by microorganisms that live in the water multiplying and living on the walls of water facilities, forming slime. It was due to this. Currently, chlorine, which is most widely used in water systems, has excellent sterilizing and bleaching properties and is therefore effective in suppressing slime formation.
Chlorine is highly corrosive to metal materials, and excessive injection of chlorine must be strictly avoided, especially in the case of copper or copper alloys, and for this reason, the concentration of chlorine in water systems has been kept to a low level. . However, effective chlorine in water systems that use tap water as make-up water (for example, small cooling towers) is completely decomposed by strong stirring by pumps or by contact with air in cooling towers, etc., and as a result, slime problems can be prevented. was incomplete. In other words, in the past, efforts were made to continuously maintain a low concentration of available chlorine in water in order to prevent corrosion in water systems.
Moreover, it was difficult to prevent slime formation. Therefore, there has been a strong desire for a drug that can solve both of these problems at the same time. An object of the present invention is to provide a water-based obstruction rod material that has excellent corrosion resistance in the coexistence of a chlorine agent and can maintain the slime obstruction removal effect. As a result of extensive research into water system damage prevention agents containing chlorine agents, the present inventors have found that a mixture of a hydantoin compound and a corrosion inhibitor has excellent properties in preventing corrosion and slime formation. They discovered this and completed the present invention. That is, the aqueous damage preventive agent for chlorine-containing agents of the present invention is characterized by containing a hydantoin compound having a specific structural formula and an anticorrosive agent. The hydantoin compound used in the present invention maintains the activity of available chlorine in water, and has the general formula: (In the formula, R ₁ and R ₂ may be the same or different, and each represents a hydrogen atom, an alkali metal,
or a halogen atom, R ₃ and R ₄ may be the same or different and each represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms. In the general formula above,
Alkali metals include sodium, potassium, lithium, etc., and halogen atoms include chlorine,
Examples of the alkyl group include bromine and iodine, and examples of the alkyl group having 1 to 12 carbon atoms include a methyl group, an ethyl group, a propyl group, and a butyl group. Specific examples of hydantoin or its derivatives represented by the above general formula include hydantoin, 5,5-dimethylhydantoin, 5-methyl-5-ethylhydantoin, 5-methyl-5-butylhydantoin, and 5-methylhydantoin.
Examples include ethyl-5-butylhydantoin and their alkali metal salts. Practically speaking, the hydatoin or its derivative used in the present invention is preferably water-soluble. As the anticorrosive agent used in the present invention, azole compounds and hydroxamic acid compounds are preferable, and in addition, phosphonic acid compounds, phosphoric acid compounds, organic phosphate ester compounds, chromic acid, dichromic acid, and molybdic acid. , nitrous acid, oxycarboxylic acid, and salts thereof. Hereinafter, the azole compounds, hydroxamic acid compounds, phosphonic acid compounds, phosphoric acid compounds, and organic phosphoric acid ester compounds will be described in detail below. The azole compound means triazoles, imidazoles or thiazoles. Any triazole may be used as long as it has a triazole skeleton, and preferably,
1,2,3-triazole itself or structural formula: 1, 2, 3 substituted at either (or both) the 4 or 5 position of the triazole ring represented by
- water-soluble 1,2,3-triazoles such as triazoles. More preferably, the triazoles are benzotriazole (the preferred triazole); 4-phenyl-1,2,3-triazole; 1,2-naphthotriazole; and 4-nitrobenzotriazole and the like. The imidazole may be any one having an imidazole skeleton, preferably imidazole itself or the structural formula: A water-soluble imidazole such as an imidazole substituted at the 2, 4 or 5 position (or some of these positions) of the imidazole ring. More preferably imidazole; adenine;
Guanine; Benzimidazole; 5-methylbenzimidazole; 2-phenylimidazole; 2
-benzylimidazole; 4-allylimidazole; 4-(betahydroxyethyl)imidazole; purine; 4-methylimidazole; xanthine; hypoxanthine; 2-methylimidazole and the like. The thiazole may be any thiazole as long as it has a thiazole skeleton, preferably thiazole itself or the structural formula: A water-soluble thiazole such as a thiazole substituted at the 2, 4 or 5 position (or some of these positions) of the thiazole ring. More preferred are thiazole, 2-mercaptothiazole, 2-mercaptobenzthiazole, benzthiazole and the like. As long as the substituted azole is water-soluble, the substituent of the above azole compound can be alkyl,
Can be aryl, aralkyl, alkylol and alkenyl groups. Hydroxamic acid compounds are generally represented by nitrogen-acylated hydroxyamines, and usually have keto and enol tautomers, both of which can be used in the present invention. Examples of acyl groups include acetyl, valeryl, aproyl, capryloyl, capryl, etc. having 2 carbon atoms.
-10 alloyl, C2-10 alkanedioyl such as oxalyl, malonyl, succinyl, and glutaryl, and aromatic acyl groups such as benzoyl, naphthoyl, and naphthaledioyl. Examples of hydroxamic acids in which an acyl group is introduced into hydroxylamine include CH ₃ CONHOH (acetohydroxamic acid), CH ₃ (CH ₂ ) ₄ CONHOH (caproylhydroxamic acid), (CONHON) ₂ (oxalylhydroxamic acid),

[Formula] (benzoyl hydroxide samic acid),

Examples include [Formula] (naphthaledioylhydroxamic acid). In addition, these hydroxamic acid salts include alkali metal salts such as sodium salts and potassium salts, hydrazine salts, amine salts such as alkanolamine salts,
and ammonium salts. The phosphonic acid compound is, for example, an organic phosphonic acid, and four typical examples are shown below using the general formula. (In the formula, X is hydrogen or a lower alkyl group, Y is hydrogen, a lower alkyl group, or a hydroxyl group, n is an integer of 1 to 10, and Z ₁ to _{Z 4} are hydrogen, an alkali metal, or an ammonium group.) (In the formula, X ₁ to X ₃ and Y ₁ to _{Y 3} are hydrogen or a lower alkyl group, and Z ₁ to _{Z 6} are hydrogen, an alkali metal, or an ammonium group.) (In the formula, X ₁ to X ₄ and Y ₁ to _{Y 4} are hydrogen or a lower alkyl group, and Z ₁ to _{Z 6} are hydrogen, an alkali metal, or an ammonium group.) (In the formula, R is hydrogen, a lower alkyl group or a carboxyl group, R ₁ is hydrogen or a methyl group, and Z ₁ to _{Z 5} are hydrogen, an alkali metal or an ammonium group.) Representative examples contained in each of the above compounds Examples of the compounds include hydroxyethylidene diphosphonic acid, aminotri(methylenephosphonic acid), ethylenediaminetetra(methylenephosphonic acid)phosphonobutanetricarboxylic acid, and salts thereof. Each of these may be used alone, or two or more types may be used in combination. Examples of phosphoric acid compounds include orthophosphoric acid, primary phosphoric acid, secondary phosphoric acid, pyropic acid, tripolyphosphoric acid, trimetaphosphoric acid, hexametaphosphoric acid, ultraphosphoric acid, and salts thereof. Each of these may be used alone, or two or more types may be used in combination. As the organic phosphate ester compound, one or two selected from the group consisting of phosphoric esters of alkyl alcohols such as methyl phosphoric esters, phosphoric esters such as methyl cellosolve, and phosphoric esters of polyoxyalkylated polyols.
It includes more than just species. In the present invention, a chlorine agent refers to one that generates available chlorine in water. In addition, a water system containing a chlorine agent includes a water system that contains a chlorine agent in make-up water, and in addition to the hydantoin compound and anticorrosive agent of the present invention, an anti-damage agent that is added to the chlorine agent is also added. As a result, water systems containing chlorine agents are also included. Water systems targeted by the water system failure preventive agent of the present invention include, for example, open water systems include chemical factories, small cooling towers that use tap water as make-up water in air conditioning/heating facilities of buildings and factories, and circulating water systems in paper and pulp factories. An example of a closed water system is a cooling water system in an internal combustion engine. In particular, as water system facilities,
For example, the anticorrosion effect of the present invention is remarkable when the material of the air conditioning/cooling/heating equipment is copper or copper alloy, and when a chlorine agent is present in the make-up water. The method for treating a water system using the inhibitor of the present invention is not particularly limited as long as it is a commonly used treatment method, and for example, the inhibitor of the present invention may be mixed into the water system to be treated. The solution may simply be added. The amount of the hydantoin compound added is preferably 0.5 mol or more, more preferably 1 mol or more, based on the available chlorine in the make-up water in the irrigation water system, and the anticorrosive agent is preferably 0.1 to 100 mol or more.
mg/, more preferably 1 to 20 mg/. If the amount added is outside the above range,
In particular, in the presence of a chlorine agent, the effect of preventing corrosion and slime formation in a water system containing copper-based metal materials is insufficient, or an increase in effectiveness cannot be expected by adding too much. As mentioned above, the anti-scaling agent of the present invention may further contain a scale inhibitor, and specific examples thereof include polyacrylic acid, partial hydrolyzate of polyacrylamide, acrylic acid-itaconic acid copolymer, Various polymers such as isobutylene-maleic anhydride copolymer, styrene sulfonic acid-maleic anhydride copolymer, and 2-hydroxyethyl methacrylic acid-acrylic acid copolymer, as well as ligninsulfonic acid, tannin, ethylenediamine, and nitrilotriacetic acid etc., and one or more types selected from the group consisting of these. Hereinafter, the anti-failure agent of the present invention will be explained in more detail with reference to Examples and Comparative Examples. Example 1 An anti-failure agent of the present invention was prepared consisting of 10 parts by weight of hydroxyethylidene bis(methylsulfonic acid), 10 parts by weight of sodium polyacrylate (molecular weight approximately 3000), and 1 part by weight of 5,5-dimethylhydantoin. did. This inhibitor 21mg/, amount of water held
Concentrated water (electrical conductivity 958μS/cm, M alkalinity 240mg/, Ca hardness 230mg/, Chlorine ion 50
mg/, sulfate ion 70mg/, silica 120mg/,
PH8.7) to create test water. A mild steel test piece was immersed in this test water, and two weeks later, the difference in weight (corrosion rate) between the test piece before and after the test was measured. From this, the corrosion rate (mg/dm ²・day) was calculated, and the corrosion prevention effect was determined. I judged it. In addition, residual chlorine in make-up water and circulating water was measured every day, and the average value is shown. Comparative Examples 1 and 2 The same procedure as in Example 1 was carried out except that the test piece in Example 1 was made of synthetic rubber and 5,5-dimethylhydantoin was excluded from the inhibitor (Comparative Example 1).
A blank test (Comparative Example 2) was conducted. The results of Example 1 and Comparative Examples 1 and 2 are shown in Table 1.

[Table] From Table 1, it was confirmed that the inhibitor of the present invention is extremely effective in preventing corrosion of mild steel and preventing slime adhesion. In addition, almost the same results were obtained when a mixture of sodium tripolyphosphate and zinc sulfate; a mixture of sodium hexametaphosphate and zinc sulfate was used in place of the phosphonic acid in the inhibitor of the present invention. Examples 2 to 7 Supply to Yokohama City Water 1 test tank, and
The temperature was maintained at 40°C. Test water was prepared by adding predetermined amounts (shown in Table 2) of hypochlorous acid, tolyltriazole, and 5,5-dimethylhydantoin to this water tank. As a test piece in this test water
Tcup (pure copper) (Examples 2 to 4) or BSTF (aluminum brass) (Examples 5 to 7) as a test piece was immersed and stirred. The test was repeated every two days, and a predetermined amount of chlorine agent (shown in Table 2) was added every day. After 7 days had elapsed, test pieces were taken out, and the anticorrosion effect of the present invention was determined in the same manner as in the examples. Comparative Examples 3 to 14 Tolyltriazole and 5,5-dimethylhydantoin were excluded from the inhibitors in Examples 2 to 4 (Comparative Examples 3, 5, and 7), and 5,
Excluding 5-dimethylhydantoin (Comparative Example 4,
6, 8), excluding tolyltriazole and 5,5-dimethylhydantoin from the inhibitors in Examples 5 to 7 (Comparative Examples 9, 11, 13), and excluding 5,5-dimethylhydantoin from the inhibitors (Comparative Examples 9, 11, 13) Examples 10, 12, and 14) were carried out in the same manner as in Examples 2 to 7. The results of Examples 2 to 7 and Comparative Examples 3 to 14 are shown in the table.
Shown in 2.

【table】

[Table] From Table 2, the combination of hydantoin compounds and anticorrosive agents significantly reduces the corrosion rate. It was also confirmed that the anti-failure agent of the present invention very efficiently inhibits corrosion of water systems made of copper and copper alloys. As is clear from the above examples, the anti-corrosion agent of the present invention has excellent anti-corrosion properties in the coexistence of chlorine agents, has the same slime removal effect as conventional agents, and prevents damage to water systems. This can be effectively prevented.

Claims (1)

[Claims] 1. General formula: (In the formula, R ₁ and R ₂ may be the same or different, and each represents a hydrogen atom, an alkali metal,
or a halogen atom, and R ₃ and R ₄ may be the same or different and each represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms) and a corrosion inhibitor. A chlorine agent-containing water system disorder preventing agent. 2. The anti-corrosion agent for water systems according to claim 1, wherein the anticorrosive agent is one or more selected from the group consisting of azole compounds and hydroxamic acid compounds. 3 The azole compound is triazole, benzotriazole, alkylbenzotriazole,
The agent for preventing damage to a water system according to claim 2, which is one or more selected from the group consisting of imidazole, thiazole, and mercaptobenzothiazole. 4. The water system disorder preventing agent according to any one of claims 1 to 3, wherein the water system contains copper or a copper alloy.