JP2003073866A - Corrosion prevention composition and corrosion prevention method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a corrosion prevention composition and to provide a corrosion prevention method, which can effectively prevent corrosion of a metallic material, with the use of a small amount of a corrosion inhibitor, in a system contacting with various kinds of industrial water such as water in a cooling tower. SOLUTION: The corrosion prevention composition includes maleimides, and a zinc-based corrosion inhibitor or a phosphorus corrosion inhibitor. The corrosion prevention method for the cooling water system is characterized by adding maleimides and the zinc-based corrosion inhibitor or the phosphorus corrosion inhibitor, to the cooling water system.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an anticorrosive composition and an anticorrosion treatment method. More specifically, the present invention relates to an anticorrosive composition and an anticorrosion treatment method capable of effectively preventing corrosion of a metal material in a system such as a cooling tower for industrial use which is brought into contact with water.

[0002]

2. Description of the Related Art In a system in which a metallic material comes into contact with water,
A chemical or electrochemical oxidation reaction occurs and corrosion progresses. Metals are produced by forcibly reducing ores existing in nature in a stable state such as oxides with carbon, etc., so it is possible to avoid the oxidation reaction, which is the direction of decreasing free energy. Absent. For this reason, various anticorrosive agents have been used in order to reduce the corrosion rate and prolong the life of devices and the like. Among the anticorrosives, phosphates, polyphosphates, phosphonates, zinc salts, etc. form insoluble salts with calcium ions in water and form an anticorrosion film on the surface of the base metal. Widely used because it is relatively inexpensive. However, the use of these anticorrosive agents has come to be regulated because they cause environmental pollution. Because of this, with lesser use,
There is a demand for a technique capable of effectively exhibiting an anticorrosion effect.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides an anticorrosion system capable of effectively preventing corrosion of a metal material in a system such as a cooling tower for various industries which is brought into contact with water by using a small amount of anticorrosive agent. The purpose of the present invention is to provide an agent composition and an anticorrosion treatment method.

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that a zinc-based anticorrosive agent or a phosphorus-based anticorrosive agent and a maleimide are used in combination.
It was found that a synergistic effect can be exhibited between the two and the amount of anticorrosive used can be reduced, and the present invention has been completed based on this finding. That is, the present invention is
(1) An anticorrosive composition comprising a maleimide and a zinc anticorrosive or a phosphorus anticorrosive, and
(2) A method for anticorrosion treatment of a cooling water system, characterized in that a maleimide and a zinc anticorrosive agent or a phosphorus anticorrosive agent are added to the cooling water system. Furthermore, as a preferred embodiment of the present invention, the anticorrosive composition according to item 1, wherein (3) the maleimide is a compound represented by the general formula [1],

[Chemical 1] (However, in the formula, R ¹ and R ² are hydrogen, an alkyl group having 1 to 5 carbon atoms or halogen, and R ³ is hydrogen, a cycloalkyl group having 5 to 8 carbon atoms, and an alkyl group having 1 to 10 carbon atoms. It is an unsubstituted or hydroxyl group-substituted alkyl group or an unsubstituted or alkyl group-substituted phenyl group having 1 to 5 carbon atoms.), (4) The content of maleimides is 0. The anticorrosive composition according to claim 1, which is 1 to 500 times by weight, and (5) the content of maleimides is 0.05 to 200 times by weight, based on the total phosphoric acid of the phosphorus anticorrosive. The anticorrosive composition according to item 2, wherein the maleimide (6) is a compound represented by the general formula [1],

[Chemical 2] (However, in the formula, R ¹ and R ² are hydrogen, an alkyl group having 1 to 5 carbon atoms or halogen, and R ³ is hydrogen, a cycloalkyl group having 5 to 8 carbon atoms, and an alkyl group having 1 to 10 carbon atoms. An unsubstituted or hydroxyl group-substituted alkyl group or an unsubstituted or C1-C5 alkyl group-substituted phenyl group.), (7) Maleimides relative to zinc of the zinc-based anticorrosive agent, The anticorrosion treatment method according to the second aspect, which is added by weight, and (8) the maleimides, with respect to the total phosphoric acid of the phosphorus-based anticorrosive agent, is added in an amount of 0.05 to 200 times by weight. A method can be mentioned.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The anticorrosive composition of the present invention contains a maleimide and a zinc anticorrosive or a phosphorus anticorrosive. In the anticorrosion treatment method of the present invention, maleimides and a zinc anticorrosive or a phosphorus anticorrosive are added to the cooling water system. According to the composition of the present invention and the method of the present invention, between maleimides and a zinc-based anticorrosive or a phosphorus-based anticorrosive, a remarkable synergistic effect on the anticorrosion effect is expressed, and a zinc-based anticorrosive or a phosphorus anticorrosive is used alone. Compared with the case where it is used for, the amount of these used can be greatly reduced and the same anticorrosion effect can be obtained. There is no particular limitation on the maleimides used in the present invention. For example, in addition to maleimide, a compound having a substituent on the nitrogen atom of maleimide, a compound having a substituent on the carbon atom at the 2-position and / or the 3-position, a maleimide ring and Examples thereof include compounds having a condensed ring with a benzene ring and the like.
In the composition of the present invention, as the maleimide, the compound represented by the general formula [1] can be preferably used.

[Chemical 3] In the general formula [1], R ¹ and R ² are hydrogen and carbon number 1
~ 5 alkyl group or halogen, R ³ is hydrogen,
A cycloalkyl group having 5 to 8 carbon atoms, an unsubstituted or hydroxyl group-substituted alkyl group having 1 to 10 carbon atoms, or an unsubstituted or alkyl group-substituted phenyl group having 1 to 5 carbon atoms. Examples of the compound represented by the general formula [1] include:
Maleimide, N-methylmaleimide, N-ethylmaleimide, N-phenylmaleimide, citraconic acid imide,
N-methyl citraconic imide, N-ethyl citraconic imide, 2,3-dimethyl maleic imide, N-methyl-2,3-dimethyl maleic imide, N-ethyl-2,3-dimethyl maleic imide, etc. Can be mentioned. These maleimides can be used individually by 1 type, or can also be used in combination of 2 or more type. Of these, maleimide can be particularly preferably used.

The zinc anticorrosive used in the present invention is not particularly limited, and examples thereof include zinc chloride, zinc bromide, zinc iodide, zinc nitrate, zinc chlorate, and zinc dithionite. These zinc-based anticorrosive agents may be used alone or in combination of two or more. There is no particular limitation on the phosphorus-based anticorrosive agent used in the present invention, for example, phosphoric acid, sodium dihydrogen phosphate,
Disodium hydrogen phosphate, phosphate such as trisodium phosphate, sodium tripolyphosphate, polyphosphate such as sodium hexametaphosphate, phosphonic acid, nitrilotrimethylenephosphonic acid, hydroxyethylidene diphosphonic acid, ethylenediaminetetramethylenephosphonic acid,
Examples thereof include phosphonates such as phosphonobutane tricarboxylic acid, ammonium phosphonate, sodium phosphonate, potassium phosphonate and calcium phosphonate. These phosphorus-based anticorrosive agents may be used alone or in combination of two or more. Further, a zinc anticorrosive and a phosphorus anticorrosive may be used in combination.

In the present invention, the ratio of the maleimides to the zinc anticorrosive agent is not particularly limited, but the maleimides are preferably 0.1 to 500 times by weight relative to the zinc of the zinc anticorrosive agent, It is more preferably 5 to 200 times by weight. When the ratio of the maleimides is less than 0.1 times by weight that of zinc of the zinc-based anticorrosive agent, the synergistic effect on the anticorrosive effect may not be sufficiently exhibited. A sufficient synergistic effect is exhibited when the ratio of the maleimides is 500 times or less with respect to the zinc of the zinc-based anticorrosive agent, and it is usually unnecessary to use maleimides exceeding 500 times the weight of the zinc of the zinc-based anticorrosive agent. . In the present invention, the ratio of the maleimides and the phosphorus anticorrosive agent is not particularly limited, but the maleimides are preferably 0.05 to 200 times by weight with respect to the total phosphoric acid of the phosphorus anticorrosive agent, and 0.2. More preferably, it is 100 times by weight. The total phosphoric acid of the phosphorus anticorrosive agent is the total amount of polyphosphoric acid and organic phosphoric acid in addition to the phosphate ion, and is expressed in terms of phosphate ion (PO ₄ ³⁻ ). The ratio of maleimides is 0.0 based on the total phosphoric acid of the phosphorus anticorrosive agent.
If it is less than 5 times by weight, the synergistic effect on the anticorrosion action may not be sufficiently exhibited. The ratio of maleimides is 200 weight times or less with respect to the total phosphoric acid of the phosphorus-based anticorrosive agent, and a sufficient synergistic effect is exhibited. No need to use. In the method of the present invention, the added amount of maleimides is preferably 0.1 to 500 mg / L, and 0.5 to 2
More preferably, it is 00 mg / L. If the added amount of maleimides is less than 0.1 mg / L, the anticorrosive effect may not be sufficiently exhibited. The amount of maleimides added is 50
The amount of 0 mg / L or less is sufficient, and normally it is not necessary to add maleimides exceeding 500 mg / L.

[0008] The dosage form of the anticorrosive composition of the present invention is not particularly limited, and for example, it can be a one-agent type drug in which a maleimide and a zinc anticorrosive or a phosphorus anticorrosive are mixed, or It is also possible to use a two-pack type drug in which a maleimide and a zinc anticorrosive or a phosphorus anticorrosive are separated. The two-component type anticorrosive agent can be mixed together at the time of use, or both can be added separately to the target aqueous system. In the composition of the present invention, maleimides and zinc anticorrosives or phosphorus anticorrosives can be used as they are, and they can be mixed with a bulking agent or other chemicals to give powders or tablets, or dissolved in a suitable solvent. It can also be used as a liquid agent. The solvent used is preferably water or a hydrophilic solvent. The hydrophilic solvent used is not particularly limited, and examples thereof include alcohols, glycols, amides, glycol esters, esters and the like. The anticorrosive composition of the present invention may further contain a biocide, a growth inhibitor, a corrosion inhibitor, a scale inhibitor, an antifoaming agent, a surfactant and the like, if necessary. INDUSTRIAL APPLICABILITY The anticorrosive composition and the anticorrosion treatment method of the present invention can be applied to a system in which a metal material comes into contact with water, such as a boiler, a cooling water system, and a radiator, and is particularly suitable for a metal material having low corrosion resistance such as carbon steel. Can be used for

[0009]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Example 1 Sodium chloride 824 mg / L (500 mg Cl
^- / L) and sodium sulphate 739 mg / L (500 mg SO ₄ ^2-
/ L) is dissolved and excess sludge from a sewage treatment plant is added so that the turbidity measured according to JIS K 0101 9.1 is 10 degrees, and further glucose 10 mg / L is added to prepare a test water. did. 1 L of this test water was placed in a beaker, and a maleimide aqueous solution and a zinc chloride aqueous solution were added so that the maleimide concentration was 1 mg / L and the zinc concentration was 0.5 mg / L, and a disk-shaped carbon steel with a diameter of 49 mm and a surface area of 38 cm ² (S
The test piece of (PCC) was immersed so that the surface was horizontal, kept at 20 to 25 ° C., and continuously rotated at 160 rpm for 7 days. After 7 days, remove the test piece and dry,
Weighed, it was determined corrosion rates from the weight difference before and after the test was 9mg / dm ² / 7days. Zinc concentration is 1 mg / L,
The same corrosion test was performed with 2 mg / L. The corrosion rates were both 5mg / dm ² / 7days. Example 2 Maleimide concentration 10 mg / L, zinc concentration 0.5 mg / L, 1 m
g / L or 2 mg / L in the same manner as in Example 1
A daily corrosion test was performed. Example 3 Maleimide concentration 50 mg / L, zinc concentration 0.5 mg / L, 1 m
g / L or 2 mg / L in the same manner as in Example 1
A daily corrosion test was performed. Example 4 Maleimide concentration 100 mg / L, zinc concentration 0.5 mg / L,
1 mg / L or 2 mg / L, in the same manner as in Example 1,
A 7-day corrosion test was performed. Comparative Example 1 Without adding the maleimide aqueous solution, only the zinc chloride aqueous solution was added, and the zinc concentration was 0.5 mg / L, 1 mg / L or 2 m.
A corrosion test was performed for 7 days in the same manner as in Example 1 except that g / L was used. Corrosion rate is 23 mg / dm ² each
^{/ 7days, 14mg / dm 2 /} 7days, was 9mg / dm ² / 7days. Comparative Example 2 Without adding the zinc chloride aqueous solution, only the maleimide aqueous solution was added, and the maleimide concentration was 1 mg / L, 10 mg / L,
A corrosion test was performed for 7 days in the same manner as in Example 1 except that the amount was 50 mg / L or 100 mg / L. Comparative Example 3 A corrosion test was performed for 7 days in the same manner as in Example 1 except that test water containing neither maleimide aqueous solution nor zinc chloride aqueous solution was used. The results of Examples 1 to 4 and Comparative Examples 1 to 3 are shown in Table 1.

[0010]

[Table 1]

As can be seen from Table 1, the corrosion rate is significantly smaller when both are used in combination, as compared with the case where only zinc chloride is added and the case where only maleimide is added.
It can be seen that there is a significant synergistic effect on the anticorrosion effect between the two. The corrosion rate of 9 mg / dm ² / 7days when only zinc chloride was added and the zinc concentration was 2 mg / L was achieved at a zinc concentration of 0.5 mg / L when maleimide was used in combination. Use approximately 25 zinc
Can be reduced to%. Example 5 1 L of the test water prepared in Example 1 was placed in a beaker, and a maleimide aqueous solution and a phosphonic acid aqueous solution were added so that the maleimide concentration was 1 mg / L and the total phosphoric acid concentration was 1 mg / L, and the diameter was 49 mm and the surface area was 38 cm ² . Disc-shaped carbon steel (SPCC)
Immerse the test piece of to make the surface horizontal, and
Maintained at -25 ° C and spun at 160 rpm for 7 consecutive days. After 7 days, take out the test piece, dry, weigh it,
When the corrosion rate was calculated from the weight difference before and after the test, it was 11 mg /
It was dm ² / 7days. Total phosphoric acid concentration 2 mg / L, 5 mg /
The same corrosion test was performed as L. The corrosion rates, respectively 6mg / dm ² / 7days, was 5mg / dm ² / 7days. Example 6 Maleimide concentration 10 mg / L, total phosphoric acid concentration 1 mg / L, 2
mg / L or 5 mg / L in the same manner as in Example 5, 7
A daily corrosion test was performed. Example 7 Maleimide concentration 50 mg / L, total phosphoric acid concentration 1 mg / L, 2
mg / L or 5 mg / L in the same manner as in Example 5, 7
A daily corrosion test was performed. Example 8 Maleimide concentration 100 mg / L, total phosphoric acid concentration 1 mg / L,
2 mg / L or 5 mg / L in the same manner as in Example 5,
A 7-day corrosion test was performed. Comparative Example 4 In the same manner as in Example 1 except that the aqueous solution of phosphonic acid was added without adding the aqueous solution of maleimide to give a total phosphoric acid concentration of 1 mg / L, 2 mg / L, or 5 mg / L, A corrosion test was performed. Corrosion rate is 42 mg / dm
^{2 / 7days, 14mg / dm 2} / 7days, it was 6mg / dm ² / 7days. The results of Examples 5-8 and Comparative Examples 2-4 are shown in Table 2.

[0012]

[Table 2]

As can be seen from Table 2, the corrosion rate is significantly smaller when both are used in combination than when only phosphonic acid is added and when only maleimide is added, and there is an anticorrosion effect between the two. It can be seen that there is a significant synergistic effect on Was added only phosphonic acid, the corrosion rate 6mg / dm ² / 7days when the total phosphate concentration 5 mg / L, when used in combination maleimide is accomplished in all the phosphate concentration 2 mg / L, the combined use of maleimide The amount of phosphonic acid used can be reduced to about 40%.

[0014]

EFFECT OF THE INVENTION According to the anticorrosive composition and anticorrosion treatment method of the present invention, a maleimide and a zinc anticorrosive or a phosphorus anticorrosive are used in combination, thereby exhibiting a remarkable synergistic effect on the anticorrosion action. Thus, the amount of zinc-based anticorrosive agent or phosphorus-based anticorrosive agent used can be reduced.

Claims (2)

[Claims] 1. An anticorrosive composition comprising a maleimide and a zinc anticorrosive or a phosphorus anticorrosive. 2. A method for anticorrosion treatment of a cooling water system, which comprises adding a maleimide and a zinc anticorrosive agent or a phosphorus anticorrosive agent to the cooling water system.