JP2001152372A - Corrosion preventive dispersant and corrosion preventing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a corrosion preventive dispersant capable of exhibiting a metal corrosion preventing effect by the addition of a small amount into an aqueous system with hardly causing toxicity and environmental contamination and to provide a corrosion preventing method using the same. SOLUTION: This corrosion preventive dispersant is composed of a water soluble copolymer obtained by copolymerizing at least two kinds of monomers, unsaturated monocarboxylic acid and/or unsaturated dicarboxylic acid and specified (substituted) amino- or amino-alkyl(meta)acrylamide. As the unsaturated monocarboxylic acid, (meta)acrylic acid is preferable, and as the unsaturated dicarboxylic acid, maleic acid is preferable. In the (substituted) amino- or ammonio-alkyl(meta)acrylamide, in the case N-substitution is taken place by at least one substitutional group, as the substitutional group, a methyl group and an ethyl group are preferable, and, also, the number of carbon atoms in alkyl of the amino- or ammonio-alkyl group is preferably 1 to 4. A monomer such as (meta)acrylamide alkylsulfonic acid of 2-acrylamide-2- methyl-propanesulfonic acid or the like can be used for copolymerization as well. The effective amount of this corrosion preventive dispersant is added to a water and used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anticorrosive dispersant and an anticorrosive method, and more particularly, to an anticorrosive dispersant which is a water-soluble copolymer having a scale-inhibiting effect and an anticorrosive effect, and adding the same to an aqueous system. The present invention relates to an improved anticorrosion method for preventing scale and metal corrosion. More specifically, the present invention relates to an anticorrosion dispersant comprising a water-soluble copolymer having a scale prevention effect and an anticorrosion effect obtained by polymerizing at least two kinds of monomers, and an aqueous anticorrosion method using the same.

[0002]

2. Description of the Related Art Carboxylic acid polymers and phosphorus compounds are used as scale inhibitors in various industrial water systems such as cooling water systems, boiler water systems and drainage systems, and metal corrosion inhibitors (ie, anticorrosives). ) As chromates, nitrites, phosphates,
Inorganic salts such as zinc salts are used. In addition, acrylic acid-based polymers are also used to obtain an anticorrosion effect and a scale prevention effect by dispersion. For example, a molecular weight of 1,000
It is known to add a homopolymer of acrylic acid of 0 or less and / or a salt thereof to an aqueous system in an amount of 100 mg / L (liter, the same applies hereinafter) or more (Japanese Patent Publication No. 58-28348). A method of adding an acrylamidomethylpropanesulfonic acid copolymer and / or a salt thereof to an aqueous system is also known, but also in this case, it is necessary to add 100 mg / L or more in order to exhibit sufficient anticorrosion performance. .

[0003]

However, among the above various anticorrosives, inorganic salts such as chromates, nitrites, phosphates and zinc salts have an anticorrosive effect, but have various problems when used. ing. That is, chromate has a strong toxicity, and its use is evaded for pollution prevention measures. Nitrite has an excellent anticorrosive effect in a closed circulating cooling water system, but in an open cooling water system, it is easily decomposed into nitrate by nitrite-oxidizing bacteria and loses its anticorrosive effect, so its use is limited. Phosphate is said to cause eutrophication when its wastewater is discharged into the sea, rivers, lakes and marshes, causing red tide. Zinc salts are highly effective as cathodic inhibitors, and are often used in combination with phosphates and the like, but their use is gradually being restricted due to their toxicity. In view of the above, non-toxic and harmless anti-corrosion agents are being studied.

On the other hand, when an acrylic acid homopolymer and / or a salt thereof or an acrylic acid-acrylamidomethylpropanesulfonic acid copolymer and / or a salt thereof is used as an anticorrosive dispersant, as described above, the amount of the added However, there is a disadvantage that economic efficiency is poor.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the above-mentioned technologies, and accordingly, it is an object of the present invention to provide an aqueous system which is substantially non-toxic, hardly pollutes the environment. It is an object of the present invention to provide an anticorrosive dispersant capable of exhibiting a metal anticorrosive effect by adding a small amount of a metal, and an anticorrosive method using the same.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, a copolymer obtained by polymerizing at least two kinds of specific monomers was excellent. The present inventors have found that they exhibit a metal anticorrosion effect, and have completed the present invention.

That is, the present invention relates to an unsaturated monocarboxylic acid,
A unit of at least one monomer selected from unsaturated dicarboxylic acids and salts thereof and a (substituted) amino- or ammonium-alkyl (meth) represented by the following general formula (1):
Acrylamides

Embedded image[However, R¹Is a hydrogen atom or a methyl group;²And R
³(And R⁴) Is a (substituted) amino group together with a nitrogen atom N, or
Is to form a (substituted) ammonium group, and n is
An integer from 1 to 13;⁴Is (substituted) ammonium
Present when forming a group]
Water containing at least two types of monomer units
An anticorrosive dispersant characterized by comprising a soluble copolymer;
And adding an effective amount of the anticorrosive dispersant to an aqueous system.
It is intended to provide a characteristic anticorrosion method. The above
In the general formula (1), “(R⁴) "Represents R together with the nitrogen atom N²
And R ³And R⁴Form a (substituted) ammonium group
If R⁴Represents a hydrogen atom or a substituent.
You.

The unsaturated monocarboxylic acid and / or its salt which can be one kind of essential monomer unit of the water-soluble copolymer as the anticorrosive dispersant of the present invention includes, for example, acrylic acid,
Methacrylic acid, salts thereof, and the like,
These can be used alone or in combination. As salts of these unsaturated monocarboxylic acids, for example,
Monovalent metal salts, divalent metal salts, ammonium salts and organic ammonium salts can be mentioned. Examples of the monovalent metal include sodium and potassium, and examples of the divalent metal include calcium and zinc. Examples of the organic amine that forms an organic ammonium group include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, cyclohexylamine, monoethanolamine, diethanolamine, triethanolamine, morpholine, and the like. These monovalent metals, divalent metals, ammonium and organic amines which form salts such as acrylic acid and methacrylic acid may be used alone or in combination of two or more in the above water-soluble copolymer. You may. Particularly preferred examples of the monomer as the monomer unit are methacrylic acid, acrylic acid, and their sodium salts from the viewpoint of cost and synthesis of a preferable copolymer.

The unsaturated dicarboxylic acid and / or its salt which can be one of the essential monomer units of the water-soluble copolymer as the anticorrosive dispersant of the present invention include, for example, maleic acid, fumaric acid, itaconic acid and the like. These salts can be mentioned, and these can be used alone or in combination. The salts of these unsaturated dicarboxylic acids are the same as those described above for the unsaturated monocarboxylic acids, and may be used alone or in combination of two or more. Particularly preferred examples of the monomer as the monomer unit are maleic acid, maleic anhydride, and the sodium salt of the former from the viewpoint of cost and synthesis of a preferable copolymer.

An unsaturated monocarboxylic acid as a monomer unit in the water-soluble copolymer constituting the anticorrosive dispersant of the present invention;
The proportion of the monomer unit of the unsaturated dicarboxylic acid and / or its salt is preferably in the range of 5 to 90 mol% based on the water-soluble copolymer. If this ratio is too large or too small, the anticorrosion performance of the copolymer tends to decrease.

The (substituted) amino- or ammonium-alkyl (meth) acrylamides which can be another kind of essential monomer unit of the water-soluble copolymer as the anticorrosive dispersant of the present invention are represented by the above general formula (1) In the general formula (1), n is preferably an integer of 1 to 4, and R ² and R ³ (and R ⁴ ) are each independently It is preferably a hydrogen atom, a methyl group or an ethyl group. In the case of (substituted) ammonium alkyl (meth) acrylamide, the (substituted) ammonium group is, for example, a positively charged cation group as shown in the following formula (2), and an anion which is a counter ion thereof. Examples thereof include a methylsulfate anion and an ethylsulfate anion, and the former is generally preferred. As other examples of R ² and R ³ (and R ⁴ ), at least one of them is a 2-hydroxyethyl group, or both of them (two) together with a nitrogen atom N are a cyclohexylamine ring or a cyclohexylammonium ring. Alternatively, it may form a morpholine ring or a morpholinium ring.

The proportion of the (substituted) amino- or ammonium-alkyl (meth) acrylamide units in the water-soluble copolymer constituting the anticorrosive dispersant of the present invention depends on the water-soluble copolymer in view of the anticorrosion performance and the like. Is preferably in the range of 5 to 60 mol%.

The water-soluble copolymer as the anticorrosive dispersant of the present invention comprises (meth) acrylamidoalkylsulfonic acid,
It is preferable from the viewpoint of its effect that the composition further contains at least one monomer unit selected from (meth) acrylamidoarylsulfonic acid and salts thereof. Here, the alkyl group of the (meth) acrylamidoalkylsulfonic acid is preferably an alkyl group having 1 to 8 carbon atoms,
The aryl group of the (meth) acrylamidoarylsulfonic acid is preferably an aralkyl group having 8 to 10 carbon atoms, and the salts thereof are the same as those described for the unsaturated monocarboxylic acid. They may be used or two or more of them may be used in combination. Examples of the monomer constituting such a monomer unit include 2-acrylamido-2-methylpropanesulfonic acid and salts thereof. Further, in this case, the use ratio of such a monomer unit is preferably 5 to 50 mol%, more preferably 5 to 40 mol%, based on the water-soluble copolymer from the viewpoint of anticorrosion performance and the like. More preferred. Other monomers that can be used in the production of the water-soluble copolymer include, for example, vinyl esters such as hydroxyethyl methacrylate and hydroxypropyl acrylate, vinyl acetate, and the like. It can be used in an amount that does not impair the effect of the agent.

The weight-average molecular weight of the water-soluble copolymer constituting the anticorrosive dispersant of the present invention is preferably in the range of 2,000 to 100,000 from the viewpoint of its anticorrosive effect.

[0015]

Next, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

As a method for producing the water-soluble copolymer constituting the anticorrosive dispersant of the present invention, a general acrylic acid polymerization method may be employed. That is, for example, an unsaturated monocarboxylic acid and / or unsaturated dicarboxylic acid and / or a salt thereof and at least two kinds of (substituted) amino- or ammonium-alkyl (meth) acrylamide represented by the general formula (1) The polymer is prepared at a monomer concentration of 20 to 60% by weight in a solvent such as water or isopropanol using a polymerization initiator such as hydrogen peroxide, ammonium persulfate, potassium persulfate or benzoyl peroxide at 10 to 120 ° C. The polymerization may be performed at the following temperature. At this time, metal salts such as cuprous chloride, cupric chloride, cupric sulfate, ferrous sulfate, and sodium bisulfite may be used, if necessary, for controlling the molecular weight.

In order to prevent corrosion of metals in an aqueous system using the water-soluble copolymer as the anticorrosive dispersant of the present invention, the copolymer concentration is 0.1 to 1000 mg / L, preferably 1 to 100 mg / L.
/ L may be added. That is, 0.1 mg / L
If the amount is less than 1,000 g / L, the anticorrosion effect cannot be obtained, and even if added at more than 1000 mg / L, the performance is almost constant, and the effect improvement with the increase in the added amount is small, which is economically irrational.

The water-soluble copolymer according to the present invention can be used as an anticorrosive dispersant in open and closed circulating cooling water systems,
In addition to the water-soluble copolymer according to the present invention, nitrous acid, phosphoric acid,
Silicic acid, molybdic acid, tungstic acid, oxyacid, so-called amino acids, aliphatic organic acids, other aliphatic amino acids, boric acid,
Lignin sulfonic acid and / or water-soluble salts thereof, anticorrosives such as tannin and lignin, anticorrosion for copper-based metals such as copper and copper alloys such as azole compounds such as benzotriazole and tolyltriazole and mercaptobenzothiazole compounds Agent, acrylic acid polymer, maleic acid polymer, methacrylic acid polymer, sulfonic acid polymer, phosphoric acid polymer, itaconic acid polymer, isobutylene polymer (for example, isobutylene unit and maleic acid unit) And / or a scale inhibitor such as a water-soluble salt thereof, an ammonium compound, an amine compound, a chlorine compound such as hypochlorous acid, a bromine compound such as hypobromous acid, Nitrogen-sulfur compounds such as isothiazolones,
Slime control agents such as organometallic compounds such as organotin compounds, polyamines such as ethylenediamine, diethylenetriamine or aminocarboxylic acids such as nitrilotriacetic acid, ethylenediaminetetraacetate, diethylenetriaminepentaacetic acid or gluconic acid, citric acid, oxalic acid, formic acid ,
It can be used in combination with, or blended with, an organic carboxylic acid-based chelating agent such as tartaric acid, phytic acid, succinic acid, and lactic acid.

Further, the water-soluble copolymer according to the present invention can be used in a heated circulation water system or a boiler water system as an anticorrosive dispersant. In this case, the water-soluble copolymer according to the present invention is prepared by adding hydrazine, sulfite, bisulfite, ascorbate, erythorbate, tannin, lignin,
Lignin sulfonate, oxygen scavenger such as glucose, alkali such as sodium hydroxide or potassium hydroxide, pH adjuster such as carbonate, orthophosphate, hexametaphosphate, hydroxyethylidene diphosphonate, phosphonobutane Inorganic or organic phosphorus compounds such as tricarboxylates, acrylic acid polymers, maleic acid polymers, methacrylic acid polymers, sulfonic acid polymers, phosphoric acid polymers,
Scale inhibitors such as itaconic acid polymers, isobutylene polymers and / or their water-soluble salts, ammonium compounds, amine compounds, chlorine compounds such as hypochlorous acid, and bromine compounds such as hypobromous acid Compounds, nitrogen-sulfur compounds such as isothiazolones, slime control agents such as organometallic compounds such as organotin compounds, ethylenediamine,
Polyamines such as diethylenetriamine or aminocarboxylic acids such as nitrilotriacetic acid, ethylenediaminetetraacetic acid salt, diethylenetriaminepentaacetic acid or organic carboxylic acid chelates such as gluconic acid, citric acid, oxalic acid, formic acid, tartaric acid, phytic acid, succinic acid, lactic acid, etc. Agent, octadecylamine, cyclohexylamine, monoethanolamine,
Use in combination with amine-based steam anticorrosives such as morpholine,
There is no problem with mixing and using.

Although the details of the anticorrosion mechanism of the water-soluble copolymer according to the present invention are not clear at present, as shown in the Examples below, by using an appropriate amount of this water-soluble copolymer, Gives excellent anticorrosion effect.

[0021]

EXAMPLES Next, the present invention will be described specifically with reference to examples, but the present invention is not limited to the examples.

Example 1 Toda City Water (referred to as "raw water" in the table below) as test water
A test solution obtained by adding a predetermined amount of each water-soluble copolymer as a solid content to 1 liter of each test water using a three-fold concentrated water of the city water was maintained at 35 ° C. using a thermostat. A metal test piece (material: SS-400, size: 5)
0 × 30 × 1 mm) suspended on a stirring rod and rotated at 170 r
immersion for 7 days while rotating at pm, corrosion rate (mg /
dm ² · day) was measured. The results are shown in Tables 1 to 4. In each table, (%) of the composition represents mol%,
The molecular weight (MW) represents the weight average molecular weight, and L represents liter.

In the table, "AA" is acrylic acid, "TMEAEMS" is methylsulfate of trimethylammonioethylacrylamide, "AMPS" is 2-acrylamido-2-methylpropanesulfonic acid, "DMPS"
"AMA" represents dimethylaminomethylacrylamide. The methyl sulfate of trimethylammonioethylacrylamide is represented by the following formula (2).

[0024]

Embedded image

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

[Table 3]

[0028]

[Table 4]

As is clear from the results shown in Tables 1 to 4, the water-soluble copolymer which is the anticorrosive dispersant of the present invention exhibits excellent anticorrosive power even in a small amount, whereas the homopolymer of acrylic acid is used. And the copolymer of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid had a poor anticorrosion effect.

[0030]

EFFECT OF THE INVENTION The water-soluble copolymer of the present invention has excellent anticorrosion properties as well as scale prevention properties, and is substantially non-toxic.
It hardly pollutes the environment.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08F 222/02 C08F 222/02 C23F 11/12 C23F 11/12 F28F 19/00 511 F28F 19/00 511Z F Terms (Reference) 4J100 AJ02P AJ08P AJ09P AK03P AK07P AK12P AK20P AK32P AM14R AM21Q AM21R BA03Q BA31Q BA32Q BA56R BC43R BC65Q CA04 CA05 JA15 4K062 AA03 BB06 BB12 BB14 BB21 CA10 DA01 FA

Claims (5)

[Claims] 1. A unit of at least one kind of monomer selected from unsaturated monocarboxylic acids, unsaturated dicarboxylic acids and salts thereof and (substituted) amino- or ammonium-alkyl represented by the following general formula (1): (Meth) acrylamides Wherein R ¹ is a hydrogen atom or a methyl group, and R ² and R
³ (and R ⁴ ) together with the nitrogen atom N form a (substituted) amino group or a (substituted) ammonium group, n is an integer from 1 to 13, and R ⁴ forms a (substituted) ammonium group A water-soluble copolymer containing at least two types of monomer units comprising at least one type of monomer unit. 2. The anticorrosive dispersant according to claim 1, wherein the unsaturated monocarboxylic acid is acrylic acid or methacrylic acid, and the unsaturated dicarboxylic acid is maleic acid. 3. In the general formula (1), R ² and R ³
(And R ⁴ ) are each independently a hydrogen atom, a methyl group or an ethyl group, and when R ² , R ³ and R ⁴ form an ammonium group together with a nitrogen atom N, a counter ion of a cation of the ammonium group Is a methylsulfate anion, and n is an integer of 1 to 4.
Or the anticorrosive dispersant according to 2. 4. The method according to claim 1, further comprising at least one monomer unit selected from (meth) acrylamidoalkylsulfonic acid, (meth) acrylamidoarylsulfonic acid and salts thereof. An anticorrosive dispersant as described in Crab. 5. An anticorrosion method comprising adding an effective amount of the anticorrosion dispersant according to any one of claims 1 to 4 to an aqueous system.