JP3169505B2 - Metal anticorrosive and metal anticorrosion method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a metal corrosion inhibitor comprising a low molecular weight and water-soluble copolymer and an improved method for preventing aqueous corrosion of a metal by adding a small amount of the metal corrosion inhibitor. About. More specifically, the present invention relates to a metal anticorrosive and a metal anticorrosion method comprising a water-soluble copolymer obtained by polymerizing at least three types of monomers that form a terpolymer or an interpolymer. Things.

[0002]

2. Description of the Related Art Inorganic salts such as chromates, nitrites, phosphates, zinc salts and the like have conventionally been used as corrosion inhibitors for metal corrosion of aqueous circulating cooling water or open circulating cooling water. Organic compounds such as acrylic acid polymers have also been used to improve the anticorrosion effect, for example, having a molecular weight of 1,000.
The following acrylic acid homopolymer and its salt 100mg
/ L or more is known (Japanese Patent Publication No. 58-2).
No. 8348).

[0003]

However, although the above-mentioned inorganic salts such as chromates, nitrites, phosphates, zinc salts and the like as anticorrosives are effective, they have various problems in their use.

That is, chromate is highly toxic,
Its use is avoided for pollution control measures. Nitrite has an excellent effect in a closed circulating cooling water system, but in an open circulating cooling water system, it is easily decomposed into nitrate by nitrite-oxidizing bacteria and loses its effect, so its use is limited. Phosphate is said to cause eutrophication and red tide when its wastewater is discharged into the sea or rivers. Zinc salt is highly effective as a cathodic anticorrosive, and is currently used in combination with phosphates, but its use is gradually being restricted due to its toxicity. Is being promoted.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a non-toxic, non-polluting environment, and a metal anticorrosive effect with a small amount of addition. An object of the present invention is to provide a metal anticorrosive which can be exerted.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that a terpolymer or an interpolymer obtained by polymerizing a specific monomer has an excellent metal anticorrosion effect. This led to the completion of the present invention.

That is, the present invention relates to (a) (meth) acrylic acid and / or a salt thereof:
90% by weight, (b) acrylamide alkyl sulfonate or acrylamide aryl sulfonate: 5 to 50% by weight, (c) at least one selected from the group consisting of vinyl ester, vinyl acetate and substituted acrylamide: 5 to 5
A metal anticorrosive comprising a water-soluble copolymer containing 0% by weight of a unit (excluding a sulfide corrosion inhibitor)
It relates metal corrosion method characterized by Ku) and said metal corrosion inhibitor is added to the aqueous system.

The unit of (a) (meth) acrylic acid and / or its salt, which is one of the units of the metal anticorrosive of the present invention, is represented by the general formula (4):

[0009]

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Wherein R ⁸ is hydrogen or a methyl group; X is hydrogen, a metal cation or N- (R ⁹ ) ₄ (where R ⁹ is hydrogen, C ₁ -C ₄ alkyl A C ₁ -C ₄ hydroxyalkyl group or a mixture thereof). ] Has the structural formula shown below.

Preferred compounds as (meth) acrylic acid and / or its salt include methacrylic acid, acrylic acid and their sodium salts.

In the water-soluble copolymer of the present invention, (a)
The proportion of the unit of (meth) acrylic acid and / or a salt thereof is 5 to 90% by weight.

The unit of (b) acrylamidoalkylsulfonate or acrylamidoarylsulfonate which is another unit of the metal anticorrosive of the present invention is represented by the following general formula (5):

[0014]

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Wherein R ¹⁰ is hydrogen or a methyl group; R ¹¹ is hydrogen or a C ₁ -C ₄ alkyl group;
R ¹² is a C ₁ -C ₈ alkyl group or a C ₈ -C ₁₀ aralkyl group, and X is the same as defined in the general formula (4). ] Has the structural formula shown below.

Preferred as the acrylamidoalkylsulfonate or acrylamidoarylsulfonate is 2-acrylamido-2-methylpropanesulfonic acid.

The proportion of the unit of (b) acrylamidoalkylsulfonate or acrylamidoarylsulfonate in the water-soluble copolymer of the present invention is 5 to 50% by weight.

Another one of the units of the metal anticorrosive agent of the present invention is (c) at least one selected from the group consisting of vinyl esters, vinyl acetates and substituted acrylamides. , General formula (1)

[0019]

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Wherein R ¹ is a halogen or methyl group, and R ² is a C ₁ -C ₆ alkyl group, a C ₆ -C ₁₀ aryl group, a C ₆ -C ₁₀ aralkyl group or a general Equation (2)

[0021]

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Wherein R ³ is hydrogen or a methyl group; R ⁴ is a C ₁ -C ₆ alkyl group or hydrogen;
n represents an integer of 1 to 3), and the unit of the substituted acrylamide is represented by the general formula (3)

[0023]

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Wherein R ⁵ is hydrogen or a methyl group, R ⁶ and R ⁷ are hydrogen, a C ₁ -C ₈ alkyl group,
A cycloalkyl group having ₆ -C _8, a benzyl group or a group represented by formula (2)

[0025]

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Wherein R ³ is hydrogen or a methyl group; R ⁴ is a C ₁ -C ₆ alkyl group or hydrogen;
n is an integer of 1 to 3), provided that both R ⁶ and R ⁷ are not hydrogen.]

Of the units (c) in the water-soluble copolymer of the present invention, preferred are t-butylacrylamide and t-butylacrylamide.
-Substituted acrylamide such as octylacrylamide.

The proportion of at least one unit selected from the group consisting of (c) vinyl ester, vinyl acetate and substituted acrylamide in the water-soluble copolymer of the present invention is 5
５０50% by weight.

The weight-average molecular weight of the water-soluble copolymer of the present invention is preferably in the range of 1,500 to 25,000 , and particularly in the case of a terpolymer, the weight-average molecular weight is 2,0.
Those in the range of 00 to 10,000 are preferred.

The method for producing the water-soluble copolymer of the present invention may be a general method for synthesizing a low molecular weight copolymer of (meth) acrylic acid.

That is, for example, at least one selected from the group consisting of (a) (meth) acrylic acid and / or a salt thereof, (b) acrylamide alkyl sulfonate or acrylamide aryl sulfonate and (c) vinyl ester, vinyl acetate and substituted acrylamide 1
The various monomers are reacted with water or in a solvent such as isopropanol using a polymerization initiator such as hydrogen peroxide, ammonium persulfate, potassium persulfate or benzoyl peroxide to form 12
The polymerization may be performed at a temperature of 0 to 200 ° C. and a polymer concentration of 25 to 50% by weight.

To protect metals in an aqueous system using the metal corrosion inhibitor of the present invention, the concentration of the polymer is 0.1 to 1,000.
mg / l, preferably in the range of 1 to 100 mg / l. In other words, if the amount is less than 0.1 mg / l, the anticorrosion effect cannot be obtained, and even if it is added more than 1000 mg / l, the performance is almost constant, and the effect is not improved with the increase of the added amount, which is economically irrational.

The metal anticorrosive of the present invention can be used as an anticorrosive in a closed circulating cooling water system or an open circulating cooling water system. In addition to the metal anticorrosive of the present invention, nitrous acid, phosphoric acid, silicic acid, molybdic acid, tungsten Anticorrosives such as acids, oxyacids, amino acids, aliphatic organic acids, aliphatic amine acids, aromatic carboxylic acids, aluminates, boric acids, ligninsulfonic acids / or their water-soluble salts, tannins, lignins,
Azo-based or mercaptobenzothiazole-based anticorrosives for copper and copper alloys such as benzotriazole and tolyltriazole, acrylic polymers, maleic polymers, methacrylic polymers, sulfonic polymers, and phosphoric acids A scale inhibitor such as a polymer, an itaconic acid-based polymer, an isobutylene-based polymer / or a water-soluble salt thereof,
Slime control agents such as ammonium compounds, amine compounds, chlorine compounds, bromine compounds, nitrogen sulfur compounds, organometallic compounds, ethylenediamine,
Amine polymers such as diethylenetriamine or aminocarboxylic acid polymers such as nitrilotriacetic acid, ethylenediaminetetraacetate, diethylenetriaminepentanoic acid or gluconic acid, citric acid, oxalic acid, formic acid, tartaric acid, phytic acid, succinic acid, lactic acid, etc. It may be used in combination with or blended with the organic carboxylic acid-based chelating agent.

The metal anticorrosive of the present invention can also be used as a heat circulating water-based or boiler water-based anticorrosive. In this case, the metal anticorrosive of the present invention is hydrazine,
Sulfite, bisulfite, ascorbate, erythorbate, tannin, lignin, ligninsulfonate,
Deoxidizers such as glucose, hydroxides, carbonates, etc.
H regulator, inorganic or organic phosphorus compounds such as orthophosphate, hexametaphosphate, hydroxyethylidene diphosphonate, phosphonobutane tricarboxylate, acrylic acid polymer, maleic acid polymer, methacrylic acid Polymer, sulfonic acid polymer, phosphoric acid polymer, itaconic acid polymer, isobutylene polymer / or a scale inhibitor such as a water-soluble salt thereof, amine polymer such as ethylenediamine, diethylenetriamine or nitrile Triacetic acid, ethylenediaminetetraacetate, aminocarboxylic acid-based polymers such as diethylenetriaminepentanoic acid or organic carboxylic acid-based chelating agents such as gluconic acid, citric acid, oxalic acid, formic acid, tartaric acid, phytic acid, succinic acid, and lactic acid; Octadecylamine, cyclohexylamine, monoethanolamine Emissions, or in combination with amine vapor based anticorrosive such as morpholine, mixing was nothing like no problem will be used.

[0035]

Although the details of the anticorrosion mechanism of the metal anticorrosive of the present invention have not been elucidated at present, as shown in the following Examples, by using an appropriate amount of this metal anticorrosive, excellent anticorrosion against metals can be obtained. Give effect.

[0036]

[Example] Toda City Water (referred to as "raw water" in the table below) and 3 times concentrated water of the city water were used as test water, and each polymer salt was used as solid content in 1 liter of each test water. The test solution to which the quantitative addition was performed was kept 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 rotating at 170 r
immersion for 7 days while rotating at pm, corrosion rate (mg /
dm ² · day). The results are shown in Tables 1 and 2.

[0037]

[Table 1]

[0038]

[Table 2]

As is evident from the results in Tables 1 and 2, the metal anticorrosive comprising the water-soluble copolymer of the present invention exhibits excellent anticorrosive properties even in a small amount. Polymer and acrylic acid and 2-acrylamide-2-
The copolymer with methylpropanesulfonic acid had poor anticorrosion effect.

[0040]

The metal anticorrosive of the present invention has excellent anticorrosion properties and is toxic and does not pollute the environment because it is a terpolymer or interpolymer organic compound.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshiaki Shibata 1-4-9 Kawagishi, Toda City, Saitama Prefecture Inside the Organo Research Institute (72) Inventor Hiroshi Wakatsuki 1-4-9 Kawagishi, Toda City, Saitama Prefecture (56) References JP-A-2-133587 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C23F 11/173

Claims (7)

(57) [Claims] (A) (meth) acrylic acid and / or a salt thereof: 5 to 90% by weight; (b) acrylamide alkyl sulfonate or acrylamide aryl sulfonate: 5 to 50% by weight; (c) vinyl ester, vinyl acetate And at least one selected from the group consisting of substituted acrylamides: 5 to 5
A metal anticorrosive comprising a water-soluble copolymer containing 0% by weight of a unit (excluding a sulfide corrosion inhibitor)
H) . 2. The water-soluble copolymer is from 1500 to 2500.
The metal anticorrosive of claim 1 having a weight average molecular weight in the range of zero. 3. The unit in the water-soluble copolymer is (a)
(Meth) acrylic acid and / or its salt: 5 to 90% by weight, (b) 2-acrylamido-2-methylpropanesulfonic acid: 5 to 50% by weight, (c) vinyl ester,
2. The metal anticorrosive according to claim 1, wherein the content of the metal anticorrosive is at least one selected from the group consisting of vinyl acetate and substituted acrylamide: 5 to 50% by weight. 4. The unit of the vinyl ester in the water-soluble copolymer is represented by the general formula (1): Wherein R ¹ is a halogen or a methyl group;
² is a C ₁ -C ₆ alkyl group, a C ₆ -C ₁₀ aryl group,
C ₆ -C ₁₀ aralkyl group or general formula (2) (Wherein R ³ is hydrogen or a methyl group, and R ⁴ is
₁ is an alkyl group or hydrogen -C _6, a metal according to claim 1 or claim 3 n is characterized by a compound represented by representing] the substituent of the 1 to 3) of the integer Anticorrosive. 5. The unit of the substituted acrylamide in the water-soluble copolymer is represented by the general formula (3): [Wherein, R ⁵ is hydrogen or a methyl group; R ⁶ and R ⁷ are hydrogen, a C ₁ -C ₈ alkyl group, a C ₆ -C ₈ cycloalkyl group, a benzyl group or a compound represented by the general formula (2) ) (Wherein R ³ is hydrogen or a methyl group, and R ⁴ is
_{1 to} C ₆ alkyl groups or hydrogen, and n is an integer of 1 to 3), provided that both R ⁶ and R ⁷ are not hydrogen. The metal anticorrosive according to claim 1 or 3, characterized in that: 6. The water-soluble copolymer is 2,000 to 1,000.
The metal anticorrosive according to claim 1, which is a terpolymer having a weight average molecular weight of 0. 7. A metal anticorrosion method comprising adding an effective amount of the metal anticorrosive according to claim 1 to an aqueous system.