JPS59196804A - Preventing agent for trouble in service water system - Google Patents

Abstract

PURPOSE:A preventing agent for trouble in service water systems, consisting of a mixture of a hydantoin based compound with a corrosion inhibitor, having improved anticorrosion properties in the presence of a chlorine agent, and capable of keeping the removing effect on slime trouble. CONSTITUTION:A preventive agent for trouble in service water systems containing a hydantoin compound, preferably a compound of the formula (R1 and R2 are H, alkali metal or halogen; R3 and R4 are H or alkyl), e.g. hydantoin, and a corrosion inhibitor. The corrosion inhibitor is preferably selected from the group of azole based compounds, e.g. triazole, benzotriazole, thiazole, mercaptobenzothiazole, etc. and hydroxamic based compounds, e.g. acetohydroxamic acid, benzoylhydroxamic acid, etc. The preventing agent for trouble is capable of suppressing very efficiently the corrosion of service water systems consisting of copper and copper alloys.

Description

[Detailed Description of the Invention] Regarding the main part ψ-jI''i@harm prevention of water systems, more details a. Corrosion of open water system or closed water system facilities and form of slime in the water system 1+) (I Defense I
Concerning ``J 2 Suru 4 Qi 1''.

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 water from industrial wastewater and sewage.

However, the use of such circulating water or filter-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, chlorine ions, and sulfate ions in the water, and trench slime damage is caused by microorganisms that live in the water, which grow and adhere to walls before irrigation water is installed, forming slime. This was due to this.

Shiohiro, which is currently most widely used in irrigation water systems, has excellent bactericidal and bleaching properties and is effective in suppressing slime formation, but on the other hand, it is highly corrosive to metals. Particularly in the case of paulownia wood or copper alloy, it is necessary to strictly avoid excessive injection, and for this reason, the concentration of the 1st element in the aqueous system has been suppressed to a low level.

However, due to ineffective chlorine in water systems that use tap water as make-up water (for example, small cooling towers), strong agitation by pumps, or contact with air in cooling towers, etc., it completely decomposes, resulting in Prevention of slime damage has been incomplete; in other words, in the past, it was difficult to continuously maintain a low concentration of available chlorine in water to prevent corrosion from entering the water system, and to prevent slime formation. Ta. 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 an anti-corrosion agent for water systems that is superior in corrosion resistance in the coexistence of chlorine agents and can maintain the effect of removing slime damage.

As a result of extensive research into preventing damage to water systems, the present inventors have discovered that a mixture of hydantoin compounds and anticorrosive agents has unique properties in preventing corrosion and slime formation. After seeing this, we have completed the present invention.

In other words, the l@'J's inhibitor for water systems of the present invention is specially designed to contain a hydantoin compound and an anticorrosive agent.

The hydantoin compound used in the present invention is particularly limited as long as it can sustain the activity of available chlorine in water.
However, it is preferable to use the following general formula: It represents a halogen atom, and may be either L3, 3V, R41J, or a single winnow, each representing a hydrogen atom or an alkyl group having 1 to 12 carbon atoms. In the general formula, examples of alkali metals include sodium hydroxide, potassium, and lithium; examples of alkali metals include nitrogen, bromine, and iodide; and examples of alkyl groups having 1 to 12 carbon atoms. Examples include a methyl group, an ethyl group, a 70-biru group, a butyl group, and the like. 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-ethyl-5-butyl. Examples include hydantoin and their alkali metal salts. The hydantoin or its derivative used in the present invention is preferably one that can be grown in water for seedlings.

Preferred anticorrosive agents to be used in the present invention are NJ1 azole compounds 97.6 and hydroxamic acid compounds; in addition, phosphonic acid compounds, phosphorus [jk compounds, organic phosphate ester compounds, chromic acid, Examples include one or more selected from the group consisting of dichromic acid, molybutic acid, nitrous acid, oxycarboxylic acid, and salts thereof. Here, azole compounds, hydroxamic acid compounds, phosphonic acid compounds, phosphoric acid compounds, and organic phosphoric acid ester compounds will be described in detail below in 1.

The azole compound means triazoles, imidazole or thiazole.

The triazole may be any triazole as long as it has a triazole skeleton, and preferably has a width of 1.213-
)') The azole itself or a water-soluble 1,2. 3-triazole. More preferably, the triazoles include U-benzotriazole (preferred triazole); 4-phenyl-1,2,3-triazole; 1,2-naphthotriazole; and 4-nitrobenzotriazole and the like.

The imidazoles may be of any type as long as they have an imidazole skeleton, and are preferably imidazole itself or the 2,4 or 5 positions of the imidazole ring represented by the structural formula: water-soluble imidazoles such as imidazoles substituted with

More preferably, imidazole: atenine; guanine:
Henzimidazole; 5-methylbenzimiguzole:
2-phenylimidazole; 2-benzylimidazole; 4-allylimitazole; 4-(betahydroxyethyl)imidazole; purine; 4-methylimidazole; xanthine; hypoxanthine; 2-methylimidazole and similar compounds. Refu.

Any theazole may be used as long as it has 1d1 thiazole circulation, preferably the thiazole itself or the 2.4 or 5 position of the thiazole ring represented by the structural formula (or any number of these positions). ) is a substituted thiazole, which is a water-soluble thiazole. More preferred examples include thiazoles 1,2-mercapdobuazole, 2-mercaftobenzthiazole, benzthiazole and the like.

Substitutions other than the above azole compounds may be alkyl, aryl, aralkyl, alkylol, and alkenyl groups, as long as the substituted azole is water-soluble.

Hydroxamic acid compounds are hydrocamic acid generally represented by nitrogen-acylated hydroxylamine,
ib usually has keto and enol tautomeric forms, both of which can be used in this invention. Examples of the acyl group include alkylyl having 2 to 10 carbon atoms such as acetyl, valeryl, kaphyl, capryloyl, and capryl, and 2 to 10 carbon atoms such as oxalyl, malonyl, succinyl, and glutaryl.
-10 alkaneshimyl and aromatic acyl groups such as benzoyl, naphthoyl, naphthalodioyl and the like. Hydroxamic acids with four acyl groups attached to hydroxylamine include, for example, CH, CONHOH (acetohydroxamic acid), cn3(cH2)4coNE1oH (caproylhydroxamic acid), (CONHOH,)2
(oxalylhydroxamic acid), ecONHOH (hair soil hydroxamic acid), and the like. In addition, the term 7 of these hydrocamic acids includes alkali metal D such as sodium salt and potassium salt.
! 44, hydrazine salts, amine salts such as alkanolamine salts, and ammonium salts.

The phosphonic acid compound is, for example, an organic phosphonic acid, and four representative examples are shown by the following general formula.

(wherein, 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, Z1
~Z4 is hydrogen, alkali metal or ammonium salt. ) (In the formula, X, ~X, and Y, ~Y, a hydrogen chloride frozen lower alkyl group, and Z! ~ Z6 are hydrogen, an alkali metal, or an ammonium group.) (In the formula, X1 to X4 and Y, -Y4 is a hydrogen pipe lower alkyl group, Z, ~Z6
hydrogen, alkali metal or ammonium group. )
(In the formula, R is hydrogen, a lower alkyl group or a carboxyl group, R1 is hydrogen or a methyl group, Z1 to Z are dihydrogen, an alkali metal, or an ammonium group.) Representative compounds contained in each of the above compounds include Examples 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, diphosphoric acid, birophosphoric 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.

The ester compounds selected from the group consisting of phosphoric acid esters of alkyl alcohols such as methyl phosphoric acid esters, phosphoric acid esters such as methyl chlorine, and phosphoric acid esters of polyoxyalkylated polyols are used. There are two or more types of mokkake.

Water system L targeted by this J#, marked water system disorder v inhibitor
r1 For example, open water systems include small cooling towers that use tap water as make-up water in air-conditioning and heating and cooling facilities in chemical factories, hills, and factories, circulating water systems in paper valve factories, and closed water systems that use internal combustion (for example, cooling water systems in 'J'1./',
. In particular, for water system facilities, for example, if the material of air conditioning and heating and cooling equipment is made of heavy steel or copper alloy,
The anticorrosion effect of the present invention is significant when a chlorine agent is present in the make-up water.

The treatment power method for water systems using the Kr damage inhibitor of the present invention is as follows:
The method is not particularly limited as long as it is a commonly used treatment method, and for example, the mixed solution of the inhibitor of the present invention may simply be added to the water system to be treated. This addition amount is such that the hydantoin compound is 0.5 mol or more based on the available chlorine in the make-up water in the irrigation water system, preferably 1 l-
i is 1 mole or more υ, i base agent is 0.1 to 100 MY/
111 preferably DJ', 1 to 20 ++y/l. If the amount added is out of the above range, it will not be possible to effectively prevent corrosion and slime formation, especially in a water system where a chlorine agent is present and also contains copper-based metal materials.

As mentioned above, the anti-scaling agent of the present invention may further contain a scale inhibiting agent, and specific examples thereof include polyacrylic acid, partial hydrolyzate of polyacrylamide, and acrylic acid-itaconic acid co-hydrolyzate. Various polymers such as inbutylene-maleic anhydride copolymer, styrene sulfonic acid to maleic anhydride, copolymer, and 2-hydroxyethyl methacrylic acid-acrylic acid copolymer, as well as lignin sulfone Examples include acids, tannins, ethylenediamine, and nitrilotriacetic acid, and one or more 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 As the anti-failure agent of the present invention, 10 parts by weight of hydroxyethylidene bis(methylphosphon fi), 10 parts by weight of polyacrylic acid powder (f+ molecular weight of about 3,000) and 5.5 parts by weight
-1 part by weight of dimethylhydantoin was prepared. This inhibitor was added to 5 times concentrated city water (conductivity 958μS/hour), which was supplied as cooling water to a small cooling tower with a holding water volume of 800/l, a residence time of 17 hours, and a blowing water volume of 481/hour. ,.

M alkalinity 240! /A! , Ca hardness 23omv//
l, chloride ion 50■/11 sulfate ion 70■/11
Silica (120 mf/I), pH 8.7) was added to prepare 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, and the corrosion rate (~/drr?・day) was calculated based on this. The effectiveness was determined. 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 test piece in Example 1 was treated with synthetic rubber, and 5% of the inhibitor was added to the synthetic rubber.
, 5-dimethylhydantoin was excluded (Comparative Example 1), and a blank test (Comparative Example 2) was also conducted.

Table 1 shows the results of Example 1, Comparative Example 1, and Comparative Example 2.
Shown below.

Table 1 According to 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, in place of the phosphonic acid in the inhibitor of the present invention, a mixture of sodium tripolyphosphate and zinc sulfate: a mixture of sodium hexametaphosphate and zinc sulfate: Even when all are used,
Similar results were obtained.

Examples 2 to 7 Yokohama City Water 11 was supplied to a test tank, and the tank was maintained at a constant temperature of 40°C. Test water was prepared by adding predetermined amounts (shown in Table 2) of hypochlorous acid, tolyltriazole, and 5,5-dimethylhytamine to this water tank.Tcup (pure copper) ( Example 2~
4) Or BSTF (aluminum brass) (Examples 5 to 7) as a test piece was immersed and stirred. The test was changed to a 2-day test, and the chlorine agent was administered in the prescribed amount (shown in Table 2) every day.
was added. After 7 days had elapsed, a test piece was taken out, and the anticorrosion effect of the present invention was evaluated in the same manner as in Example.

Tolyl) U azole and 5,5-dimethylhydantoin were excluded from the inhibitors in Examples 2 to 4 (Comparative Example 3)
, 5.7) and excluding 5,5-dimethylhydantoin from the same inhibitor (Comparative Examples 4 and 6.8), and Examples 5 to
From the inhibitor in 7 to tolyltriazole and 5,5
-Excluding dimethylhydantoin (Comparative Example 9, 11.13
) and Examples 2 to 7 except that 5,5-dimethylhydantoin was excluded from the inhibitor (Comparative Example 10.12.14)
I did the same thing.

The results of Examples 2 to 7 and Comparative Examples 3 to 14 are shown in Table 2.

Table 2 According to Table 2, it was confirmed that the anti-failure agent of the present invention very efficiently inhibits corrosion of water systems made of copper and gunmetal.

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 nullime removal effect as conventional agents, and prevents damage to water systems. It is something that can be effectively prevented.

Claims (1)

[Scope of Claims] J. An agent for preventing damage to a water system, comprising: a hydantoin compound and an anticorrosive agent. 2. The hydantoin compound has the general formula: (formula, in, R
. , each has a hydrogen atom and a carbon number of 1~
representing an alkyl group of 12)
The agent for preventing disorders of the Kosui system described in l. 3. The anticorrosive agent is selected from the group consisting of azole compounds and hydroxamic acid compounds. Item 1: An anti-damage agent for npi-soft water systems. 4. The azole compound is selected from the group consisting of triazole, benzotriazole, alkylbenzotriazole, imidazole, thiazole, and mercaptobenzothiazole. Well 1 water system disorder prevention agent. 5. Any one of claims 1 to 4, in which the water system contains copper or a copper alloy; gl
J., an agent for preventing damage to irrigation water systems.