JPS6145708B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD This invention relates to metal corrosion inhibitors. More specifically, metal corrosion inhibitors in general water systems such as cooling water,
In particular, it relates to metal corrosion inhibitors for steel, mild steel, cast iron, etc. So-called water induction devices, such as steam production devices,
In heating systems, chemical reaction plants, cooling water systems, etc., water comes into contact with the metals (iron, mild steel, cast iron, copper, etc.) that make up the equipment, and corrosion is likely to occur. To prevent this, various anticorrosive agents and methods have been proposed and used. However, among the conventionally used anticorrosive agents, chromic acid compounds such as potassium dichromate, which were recognized as excellent, are rarely used due to toxicity issues, and other heavy metal ions such as zinc ions are used. Also, the use of polymerized phosphates and the like is gradually being restricted due to pollution regulations. In view of these points, the inventors of the present invention have conducted intensive research and found that conventional heavy metal ions can be used by combining a copolymer of a specific alkylolamide and an alkenyl compound with a specific heavy metal ion. The present inventors have discovered the fact that a new metal anticorrosive agent that exhibits a better anticorrosive effect than conventional metal anticorrosive agents can be obtained, and as a result, the amount of heavy metal ions used can be reduced, and this invention has been achieved. Thus, according to this invention, (a) general formula (), One or more alkylolamide compounds represented by the general formula (), A metal anticorrosive agent is provided which contains as active ingredients a copolymer with one or more alkenyl compounds represented by (b) a compound capable of liberating heavy metal ions in water. In the above general formula (), R ₁ and R ₂ are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and X is one bond or a carbon number 1
It is an alkylene group which may have ~8 branches. When X is an alkylene group, it preferably has 1 to 5 carbon atoms, most preferably 1 to 3 carbon atoms, from the viewpoint of solubility and the like. Furthermore, in the above general formula (), R ₃ , R ₄
and R ₅ are each independently a hydrogen atom or a methyl group, and A is a hydroxyl group or -OR ₆ (in the formula,
R ₆ is a lower alkyl group optionally substituted with one hydroxyl group, or -NH ₂ or -NHR ₇
(In the formula, R ₇ represents a lower alkyl group whose terminal may be substituted with -SO ₃ H). Specific examples of the alkylolamide compound of general formula () include N-hydroxyacrylamide,
N-hydroxymethacrylamide, N-methyl-
N-hydroxyacrylamide, N-methylol acrylamide, N-methylol methacrylamide, N-methyl-N-methylol acrylamide, N-methyl-N-methylol methacrylamide, N-ethyl-N-methylol acrylamide, N-ethyl-N- Methylol methacrylamide, N-hydroxyethylacrylamide, N-
Hydroxyethyl methacrylamide, N-methyl-N-hydroxyethylacrylamide, N-methyl-N-hydroxyethyl methacrylamide,
N-ethyl-N-hydroxyethylacrylamide, N-ethyl-N-hydroxyethylmethacrylamide, N-propyl-N-hydroxyethylacrylamide, N-hydroxypropylacrylamide, N-hydroxypropylmethacrylamide, N-hydroxyisopropylacrylamide, Examples include N-hydroxyisopropyl methacrylamide. Among these, N-methylolacrylamide and N-hydroxyethylacrylamide are preferably used from the viewpoint of ease of synthesis, cost, etc. Specific examples of alkenyl compounds of general formula () include acrylic acid, methacrylic acid, crotonic acid,
Isocrotonic acid, trans-2-methylcrotonic acid, 2-methyl-isocrotonic acid, acrylamide, methacrylamide, N-methylacrylamide, N-ethylacrylamide, N-propylacrylamide, acrylamide-N-methylpropanesulfonic acid, methyl acrylate, Methyl methacrylate, methyl crotonate, ethyl acrylate, ethyl methacrylate, ethyl crotonate, propyl acrylate, propyl methacrylate, propyl crotonate, butyl acrylate, butyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate etc. Among these, acrylic acid, methacrylic acid, acrylamide, etc. can be preferably used. The copolymer used in this invention is a copolymer obtained by subjecting one or more of the above alkylolamide compounds and one or more of the above alkenyl compounds to known polymerization conditions, Usually, it is appropriate to copolymerize the alkylolamide compound with a monomer ratio such that the alkylolamide compound is at least 20% by weight or more based on the total monomer amount of the alkylolamide compound and the alkenyl compound. It is preferable that the alkenyl compound has a molar ratio of 0.4 to 4. Furthermore, if the molecular weight exceeds 100,000, aggregation occurs, which is not preferable. Therefore, a molecular weight of about 500 to 100,000 is suitable, and a molecular weight of about 1,000 to 10,000 is usually preferred. These copolymers include, for example, one or more alkylolamide compounds and one or more alkenyl compounds in water, a water-containing solvent, or an organic solvent (e.g., lower alcohol, dioxane, aromatic It can be obtained by heating a polymerization initiator (for example, inorganic and organic peroxides such as persulfates and benzoyl peroxide, azobisisobutyronitrile, redox catalysts, etc.) in a solvent (solvent, etc.). Note that when the polymerization reaction is carried out under acidic conditions, crosslinking is likely to occur and a three-dimensional structure is likely to occur, which may reduce the solubility and dispersibility of the produced polymer. Therefore, it is desirable to carry out the polymerization reaction under alkaline conditions by adding sodium hydroxide or the like. However, no matter what structure the obtained copolymer has, the desired solubility (including when made into a salt),
Any conditions can be used as long as they exhibit dispersibility. When the copolymers thus obtained are used as metal corrosion inhibitors, they need to be substantially water-soluble. Therefore, if the obtained copolymer is difficult to dissolve in water, in order to obtain the desired effect, it is necessary to increase the solubility by converting the free acid or its ester moiety in the copolymer into the corresponding salt. desirable. In this case, lithium, sodium, potassium and ammonium salts are preferred, and sodium and potassium salts are more preferred. On the other hand, compounds that can liberate heavy metal ions in water include hydrochloride and sulfate of zinc, tin or manganese, among which zinc chloride, zinc sulfate, manganese chloride, manganese sulfate and tin chloride are used. is preferred. There is also no problem in using a mixture of two or more of these. The above two active ingredients (a) and (b) of this invention are usually used as an anticorrosive agent in the form of a liquid solution dissolved in water or a powder powder that is directly mixed. As a solvent, it is added directly to a solution of copolymerization of one or more of the above-mentioned alkylolamide compounds and one or more of alkenyl compounds in an aqueous medium, or after adjusting the pH as appropriate. It is convenient to prepare by dissolving a compound capable of liberating heavy metal ions. In addition, the preferred ratio for achieving the synergistic effect of each compound (a) and (b) is active ingredient (a):active ingredient (b)
is in a weight ratio of 1:0.05 to 5, preferably 1:0.1 to
It is 1. Therefore, it is appropriate to prepare the formulation at such a content ratio. As a result of further research, the inventors of this invention have discovered that the synergistic effect between the active ingredient (a) and the active ingredient (b) defined above shows that the aliphatic oxycarboxylic acid or its salt or the phosphonic acid or its salt It has been found that the effect can be improved by adding it as a component. Therefore, from this point of view, according to the present invention, a copolymer (a) of an alkylolamide compound and an alkenyl compound, a compound capable of liberating heavy metal ions in water
There is provided a metal corrosion inhibitor containing (b) and an aliphatic oxycarboxylic acid or its salt (c) as a third component as active ingredients. Furthermore, a metal corrosion inhibitor containing (a), (b) and a phosphonic acid compound (c) as a third component as active ingredients is provided. Among the third component (c), examples of aliphatic oxycarboxylic acids or salts thereof include citric acid, tartaric acid, malic acid, gluconic acid, tartaric acid, lactic acid, and alkali metal or ammonium salts thereof such as sodium and potassium. It will be done. Among these, gluconic acid, citric acid, or alkali metal or ammonium salts thereof are preferred, and sodium salts are more preferred. Also, two or more of these may be used. Of the third component (c) above, the phosphonic acid compound means phosphonic acid, aminophosphonic acid, phosphonocarboxylic acid, or a salt thereof, and specifically, nitrilotrismethylphosphonic acid, ethylenediaminetetrakismethylphosphonic acid, Hexamethylenediaminetetrakismethylphosphonic acid, 1,
1-hydroxyethane diphosphonic acid, 1,1-aminoethane diphosphonic acid, 1-phosphonopropane-2,3-dicarboxylic acid, phosphonosuccinic acid,
Examples include 2phosphonobutanetricarboxylic acid and alkali metal or ammonium salts thereof.
Among these, 1,1-hydroxyethanediphosphonic acid, nitrilotrismethylphosphonic acid, 2-
Phosphonobutane-1,2,4-tricarboxylic acid and its alkali metal or ammonium salts are preferred. The appropriate blending ratio of the three-component anticorrosive agent of this invention is active ingredient (a):active ingredient (b) in a weight ratio of 1:
It is 0.05 to 5, preferably 0.1 to 1, and it is appropriate that the active ingredient (c) is blended in an amount of 0.2 to 5 per 1 of the total weight. . Further, the above-mentioned three-component anticorrosive agent is usually used in the form of a liquid or powder, similar to the above-mentioned two-component anticorrosive agent. The above (a), (b) binary components and (a), (b), (c)
When using water-based metal corrosion inhibitors consisting of three components, the amount added to the object to be protected against corrosion is not particularly limited as it varies depending on various conditions, but usually 5 to 1000 ppm as the active ingredient, preferably. The purpose can be achieved by adding 20 to 100 ppm. Therefore, this invention has (a), (b)
The present invention also provides a method for preventing corrosion of water-based metals, which comprises adding each component or each of the three components (a), (b), and (c) to a system to be protected against corrosion. In this case, each component may be formulated and used separately. The metal anticorrosive agent of the present invention exhibits an excellent anticorrosion effect due to the synergistic action of a copolymer of a specific alkylolamide compound and an alkenyl compound and heavy metal ions. And the effect is further increased by adding certain third components. Therefore, superior effects can be obtained at lower concentrations than conventional heavy metal-based corrosion inhibitors, and it is useful as a corrosion inhibitor for steel, mild steel, cast iron, etc. in various general water systems. The metal corrosion inhibitor of the present invention can be used in combination with various conventional anticorrosive additives having additive effects, such as molybdates, nitrites, polymerized phosphates, lignin, tannins, aromatic carboxylic acids, etc. No problem. Furthermore, for systems containing copper-based metals, there is no problem in using benzotriazole, tolyltriazole, mercaptobenzothiazole, etc. in combination. Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereby. Example 1 A corrosion prevention test was conducted on a mild steel test piece using 5 times more concentrated Osaka city water. A test solution 1 containing a predetermined amount of drug is placed in a flat-bottomed beaker 1,
A mild steel test piece is suspended from the tip of a stirring rod linked to a motor and immersed in the liquid. Attach a thermostat and maintain the liquid temperature at 50℃ with a mantle heater, and test for 5 days while rotating the test piece at a speed of 200 rpm. After completion, observe the surface of the test piece, and then measure the weight after pickling according to JIS K0101. From the pre-measured weight of the test piece at the start of the test and its subsequent weight, mdd
m ² ·day), that is, the corrosion loss per dm ² per day is measured. The test piece used is the commercial product name,
Spcc, the shape is a rectangular plate of 30 x 50 x 1 mm. Table 1 shows the quality of the test water used, and Table 2 shows the mud results obtained.

【table】

【table】

[Table] Example 2 A test similar to Example 1 was conducted using Osaka city water. Table 3 shows the water quality, and Table 4 shows the results.

【table】

【table】

[Table] Example 3 In order to investigate the performance in boiler water, the following tests were conducted using an autoclave. 500 c.c. of the test liquid was placed in a 500 c.c. stainless steel container with a flange that could be tightly sealed. The test liquid is a liquid obtained by adding a predetermined amount of chemicals to synthetic boiler water. A mild steel test piece was suspended from the tip of a stirring rod linked to the motor, and ^the test piece was completely sealed.
The test was conducted for 5 days while rotating the test piece in the liquid at 100 rpm under pressurized conditions (°C). The results obtained are shown in Table 6, and the quality of the soft water used is shown in Table 5. This water is synthetic boiler water that is 10 times the make-up water used in a boiler used by a certain company.

【table】

【table】

【table】

Claims (1)

[Claims] 1 (a) General formula (): (In the formula, R ₁ and R ₂ are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms;
an alkylene group which may have two bonds or a branch having 1 to 8 carbon atoms); and one or more alkylolamide compounds represented by the general formula (): [In the formula, R ₃ , R ₄ and R ₅ are each independently a hydrogen atom or a methyl group; A is a hydroxyl group or -OR ₆ (wherein, R ₆ is a lower alkyl group optionally substituted with one hydroxyl group) ) group or -NH ₂ or -NHR ₇ (wherein R ₇ is a group whose terminal is -
A copolymer with one or more alkenyl compounds represented by (lower alkyl group optionally substituted with SO ₃ H) and (b) a compound capable of liberating heavy metal ions in water. A metal anticorrosive agent characterized by containing it as an ingredient. 2 The alkylolamide compound of general formula () is N-hydroxyacrylamide, N-hydroxymethacrylamide, N-methyl-N-hydroxyacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, N-methyl-N-methylol Acrylamide, N-methyl-N-methylolmethacrylamide, N-ethyl-N-methylolmethacrylamide, N-ethyl-N-methylolmethacrylamide, N-hydroxyethylacrylamide, N-hydroxyethylmethacrylamide, N-methyl-N -Hydroxyethyl acrylamide, N-methyl-N-hydroxyethylmethacrylamide, N-ethyl-
N-hydroxyethyl acrylamide, N-ethyl-N-hydroxyethylmethacrylamide, N
-Propyl-N-hydroxyethylacrylamide, N-hydroxypropylacrylamide, N
-Hydroxypropylmethacrylamide, N-hydroxyisopropylacrylamide, or N-
The metal anticorrosive agent according to claim 1, which is hydroxyisopropylmethacrylamide. 3. The metal corrosion inhibitor according to claim 1 or 2, wherein the alkylolamide compound of general formula () is N-methylolacrylamide or N-hydroxyethylacrylamide. 4 The alkenyl compound of general formula () is acrylic acid, methacrylic acid, crotonic acid, isocrotonic acid, trans-2-methylcrotonic acid, 2-methyl-isocrotonic acid, acrylamide, methacrylamide, N-methylacrylamide, N-ethyl Acrylamide, N-propylacrylamide,
Acrylamide-N-methylpropanesulfonic acid, methyl acrylate, methyl methacrylate, methyl crotonate, ethyl acrylate,
Ethyl methacrylate, ethyl crotonate, propyl acrylate, propyl methacrylate,
Propyl crotonate, butyl acrylate, butyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate or
-Hydroxypropyl methacrylate, the metal anticorrosive agent according to any one of claims 1 to 3. 5. The metal anticorrosive agent according to any one of claims 1 to 4, wherein the alkenyl compound of general formula () is acrylic acid, methacrylic acid, or acrylamide. 6 The polymerization ratio of the copolymer is a molar ratio of 1 alkylolamide compound to 0.4 alkenyl compound.
The metal anticorrosive agent according to any one of claims 1 to 5, which is .about.4. 7. The metal corrosion inhibitor according to any one of claims 1 to 6, wherein the copolymer has a molecular weight of about 500 to 100,000. 8. The metal corrosion inhibitor according to any one of claims 1 to 7, wherein the copolymer has a molecular weight of about 1,000 to 10,000. 9 A compound that can liberate heavy metal ions in water is
The metal corrosion inhibitor according to any one of claims 1 to 8, which is a hydrochloride or sulfate of zinc, tin, or manganese. 10. The metal anticorrosive agent according to any one of claims 1 to 9, wherein the content ratio of the active ingredients is 1:0.05 to 5 by weight as active ingredient (a):active ingredient (b). 11. The metal anticorrosive agent according to any one of claims 1 to 9, wherein the content ratio of the active ingredients is 1:0.1 to 1 by weight as active ingredient (a):active ingredient (b). 12 (a) General formula (): (In the formula, R ₁ and R ₂ are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms;
an alkylene group which may have two bonds or a branch having 1 to 8 carbon atoms); and one or more alkylolamide compounds represented by the general formula (): [In the formula, R ₃ , R ₄ and R ₅ are each independently a hydrogen atom or a methyl group; A is a hydroxyl group or -OR ₆ (wherein, R ₆ is a lower alkyl group optionally substituted with one hydroxyl group) ) group or -NH ₂ or -NHR ₇ (wherein R ₇ is a group whose terminal is -
(lower alkyl group optionally substituted with SO ₃ H); (b) a copolymer with one or more alkenyl compounds represented by (b) a compound capable of liberating heavy metal ions in water; ) A metal corrosion inhibitor characterized by containing an aliphatic oxycarboxylic acid or a salt thereof as an active ingredient. 13. The metal anticorrosive agent according to claim 12, wherein the aliphatic oxycarboxylic acid or its salt is gluconic acid, citric acid, or an alkali metal or ammonium salt thereof. 14 Active ingredient (a): Active ingredient (b) in a weight ratio of 1:
0.05 to 5, and the active ingredient (c) is blended in a weight ratio of 0.2 to 5 with respect to the total weight of 1. agent. 15 Active ingredient (a): Active ingredient (b) in a weight ratio of 1:
0.1 to 1, and the active ingredient (c) is blended in a weight ratio of 0.2 to 5 with respect to the total weight of 1. agent. 16 (a) General formula (): (In the formula, R ₁ and R ₂ are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms;
an alkylene group which may have two bonds or a branch having 1 to 8 carbon atoms); and one or more alkylolamide compounds represented by the general formula (): [In the formula, R ₃ , R ₄ and R ₅ are each independently a hydrogen atom or a methyl group; A is a hydroxyl group or -OR ₆ (wherein, R ₆ is a lower alkyl group optionally substituted with one hydroxyl group) ) group or -NH ₂ or -NHR ₇ (wherein R ₇ is a group whose terminal is -
(lower alkyl group optionally substituted with SO ₃ H); (b) a copolymer with one or more alkenyl compounds represented by (b) a compound capable of liberating heavy metal ions in water; ) A metal corrosion inhibitor characterized by containing a phosphonic acid compound as an active ingredient. 17. Claim 16, wherein the phosphonic acid compound is 1,1-hydroxyethane diphosphonic acid, nitrilotrismethylphosphonic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, or an alkali metal or ammonium salt thereof. The metal corrosion inhibitor described in . 18 Active ingredient (a): Active ingredient (b) in a weight ratio of 1:
0.05 to 5, and the active ingredient (c) is blended in a weight ratio of 0.2 to 5 with respect to the total weight of 1. agent. 19 Active ingredient (a): Active ingredient (b) in a weight ratio of 1:
0.1 to 1, and the active ingredient (c) is blended in a weight ratio of 0.2 to 5 with respect to the total weight of 1. agent.