Rust inhibitor

Abstract

To provide a rust inhibitor having excellent antirust / anticorrosion performance for a wide range of metal members (e.g., iron, copper and aluminum).SOLUTION: The rust inhibitor contains a salt (AB) of an aliphatic polycarboxylic acid (A) and an alkylene oxide adduct (B) of a cyclic monoamine (b). The ratio of propylene oxide in alkylene oxides constituting the alkylene oxide adduct (B) is 50 mol% or more. Preferably, the aliphatic polycarboxylic acid (A) has 4-22 carbon atoms.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a rust preventive agent.

Background Art

[0002] Metal members (for example, iron members such as steel and cast iron; non-ferrous metal members such as copper, zinc, aluminum, and alloys of these metals) are liable to form rust such as oxides, hydroxides, or salts such as carbonates on their surfaces due to moisture, oxygen, carbon dioxide, etc. in the atmosphere, and further, corrosion progresses from the surface toward the inside and it is easily chemically deteriorated.

[0003] In order to prevent the formation of such rust, many rust preventive treatments of inorganic substances, metals, organic substances, etc. have been conventionally performed. Among these, the method of performing rust prevention with an organic film is frequently used as a simple and effective method. Examples of the rust preventive agents used for these include aqueous rust preventive agents, oil-based rust preventive agents, rust preventive greases, vaporizable rust preventive agents, etc.

[0004] As organic rust preventive agents, for example, organic rust preventive agents such as organic amine salts, carboxylic acid-based compounds, carboxylate-based compounds, sulfonate-based compounds, and heterocyclic compounds are known. For example, Patent Document 1 discloses a water-soluble corrosion inhibitor composition containing a specific polyether polyamine. Further, Patent Document 2 discloses a water-soluble rust preventive agent characterized by containing a salt of a branched carboxylic acid and an alkylene oxide adduct of a cyclic amine.

[0005] However, in the above-mentioned rust preventive agent composition, when the addition amount of the rust preventive agent is small, sufficient rust preventive performance cannot be obtained. Also, although the rust preventive performance for a specific metal is good, there is a problem that the effect on a plurality of metal members cannot be obtained. On the other hand, in recent years, for the purpose of weight reduction, etc., many metal parts in which an iron member and a non-ferrous metal member are combined have been used, and a practical rust preventive agent having high rust prevention and corrosion prevention performance is also required for the combined metal parts.

Prior Art Documents

Patent Document

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] An object of the present invention is to provide a rust preventive agent having excellent rust prevention and corrosion prevention performance against a wide range of metal members (for example, iron, copper, aluminum).

Means for Solving the Problems

[0008] As a result of intensive studies, the present inventors have arrived at the present invention. That is, the present invention is a rust preventive agent containing a salt (AB) of an aliphatic polycarboxylic acid (A) and an alkylene oxide adduct (B) of a cyclic monoamine (b), wherein the ratio of propylene oxide in the alkylene oxide constituting the alkylene oxide adduct (B) is 50 mol% or more; an aqueous rust preventive agent containing the rust preventive agent and water, and the pH (25 ° C) of the aqueous rust preventive agent is 5 to 10.

Effects of the Invention

[0009] The rust preventive agent of the present invention exhibits the effect of exerting excellent rust prevention and corrosion prevention performance against a wide range of metal members (for example, iron, copper, aluminum).

Modes for Carrying Out the Invention

[0010] The rust inhibitor of the present invention is a rust inhibitor containing a salt (AB) of an aliphatic polycarboxylic acid (A) and an alkylene oxide adduct (B) of a cyclic monoamine (b), wherein the ratio of propylene oxide in the alkylene oxide constituting the alkylene oxide adduct (B) is 50 mol% or more. The salt (AB) may contain one kind or two or more kinds.

[0011] Examples of the aliphatic polycarboxylic acid (A) include aliphatic carboxylic acids having two or more carboxyl groups, such as aliphatic dicarboxylic acids (A1), aliphatic tricarboxylic acids (A2), and aliphatic polycarboxylic acids (A3) having a valency of 4 or more.

[0012] Examples of the aliphatic dicarboxylic acid (A1) include those having 2 to 25 carbon atoms, such as linear aliphatic dicarboxylic acids [e.g., linear saturated aliphatic dicarboxylic acids {e.g., oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, heptadecanedioic acid, octadecanedioic acid, nonadecanedioic acid, eicosanedioic acid, etc.}, linear unsaturated aliphatic dicarboxylic acids {e.g., fumaric acid, maleic acid, 2- or 3-hexenedioic acid, 2- or 3-heptenedioic acid, 2-, 3- or 4-octenedioic acid, etc.}, etc.], branched-chain aliphatic dicarboxylic acids [e.g., branched-chain saturated aliphatic dicarboxylic acids {e.g., methylsuccinic acid, 2- or 3-methyladipic acid, 3,3-dimethyladipic acid, etc.}, branched-chain unsaturated aliphatic dicarboxylic acids {e.g., citraconic acid, mesaconic acid, etc.}, etc.], and alicyclic dicarboxylic acids {e.g., cyclohexanedicarboxylic acid, etc.}. Among these, from the viewpoint of rust prevention, linear aliphatic dicarboxylic acids are preferred, and linear saturated aliphatic dicarboxylic acids are more preferred.

[0013] Examples of the aliphatic tricarboxylic acid (A2) include those having 4 to 25 carbon atoms, such as chain-saturated aliphatic tricarboxylic acids {e.g., methane tricarboxylic acid, tricarballylic acid}, maleates of unsaturated monocarboxylic acids (including those having 8 to 21 carbon atoms, e.g., oleic acid, vaccenic acid, ricinoleic acid, linoleic acid, eleostearic acid, mead acid, etc.), alicyclic tricarboxylic acids {e.g., cyclohexane tricarboxylic acid, etc.}.

[0014] Examples of the aliphatic polycarboxylic acid (A3) include those having 5 to 25 carbon atoms, such as chain aliphatic polycarboxylic acids {e.g., methane tetracarboxylic acid, butane-1,1,1,2-tetracarboxylic acid, butane-1,1,1,3-tetracarboxylic acid, maleates of unsaturated dicarboxylic acids, etc.}.

[0015] From the viewpoint of rust prevention, the number of carbon atoms per carboxyl group of the aliphatic polyvalent carboxylic acid (A) ((the number of carbon atoms of (A)) / (the number of carboxyl groups in (A))) is preferably 1 to 20, more preferably 3 to 15. When within this range, the balance between the film-forming ability of the hydrophobic group (hydrocarbon group) and the water solubility and metal adsorption ability of the carboxyl group is good, and a rust-preventive film with a high ability to shield water and oxygen on the metal surface is likely to be formed, and a rust prevention effect is likely to be obtained.

[0016] As the aliphatic polycarboxylic acid (A), from the viewpoint of water solubility, an aliphatic polycarboxylic acid having 4 to 22 carbon atoms is preferable, more preferably an aliphatic polycarboxylic acid having 6 to 16 carbon atoms, and particularly preferably an aliphatic polycarboxylic acid having 8 to 14 carbon atoms. Further, from the viewpoint of the balance between rust prevention property and water solubility, an aliphatic polycarboxylic acid having 4 to 22 carbon atoms is preferable, more preferably a 2- to 3-valent aliphatic polycarboxylic acid having 10 to 22 carbon atoms, and particularly preferably dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, heptadecanedioic acid, octadecanedioic acid, and a maleinated product of an unsaturated monocarboxylic acid (having 14 to 18 carbon atoms). When within this range, the balance between the film-forming ability by the hydrophobic group (hydrocarbon group) and the water solubility and metal adsorption ability by the carboxyl group is good, and a rust prevention film having a high ability to shield water and oxygen on the metal surface tends to be easily formed.

[0017] The cyclic monoamine (b) includes a cyclic hydrocarbon group-containing monoamine and a heterocyclic monoamine having 4 to 12 carbon atoms. For example, saturated cyclic monoamines [e.g., alicyclic amines (cyclic saturated hydrocarbon group-containing monoamines) {e.g., cyclobutylamine, cyclopentylamine, cyclohexylamine, cycloheptylamine, dicyclohexylamine, N-methylcyclohexylamine, trimethylcyclohexylamine, aminomethylcyclohexane, 1-cyclohexylethylamine, etc.}, saturated heterocyclic monoamines {e.g., morpholine, piperidine, etc.}, etc.], unsaturated cyclic monoamines (cyclic unsaturated hydrocarbon group-containing monoamines) [e.g., aromatic amines {e.g., aniline, anisidine, toluidine, trimethylaniline, etc.}, unsaturated heterocyclic monoamines {e.g., pyrrole, azepine, azonine, etc.}, etc.] can be mentioned. Among these, from the viewpoint of rust prevention property, a saturated cyclic monoamine having 6 to 12 carbon atoms is preferable, more preferably an alicyclic monoamine having 6 to 12 carbon atoms, and particularly preferably cyclohexylamine and dicyclohexylamine. In the present invention, since the alkylene oxide adduct (B) has a bulky group derived from the cyclic functional group of (b), it is presumed that due to the steric hindrance of (B), a rust preventive film can be uniformly formed on the metal surface even with a small amount of the salt (AB).

[0018] In the present invention, the alkylene oxide adduct (B) is an alkylene oxide adduct of the cyclic monoamine (b), and the alkylene oxide includes those having 2 to 3 carbon atoms. For example, ethylene oxide (which may be abbreviated as EO hereinafter), propylene oxide {for example, 1,2 - propylene oxide (which may be abbreviated as PO hereinafter), 1,3 - propylene oxide, etc.} and the like can be mentioned.

[0019] The ratio of propylene oxide in the alkylene oxide constituting the alkylene oxide adduct (B) is 50 mol% or more, and from the viewpoint of metal affinity, it is preferably 60 to 100 mol%, and more preferably 80 to 100 mol%. When the ratio of propylene oxide is 50 mol% or more, the salt (AB) easily moves near the metal in the solution (especially in an aqueous solution), the adsorption force is improved, and sufficient rust preventive properties can be obtained with a low addition amount.

[0020] From the viewpoint of rust preventive properties, the average number of moles of alkylene oxide added per molecule in the alkylene oxide adduct (B) contained in the rust preventive agent is preferably 1 to 8 moles, and more preferably 1 to 4 moles. In addition, the calculation of the average number of moles of addition is based on the amount of the cyclic monoamine (b) contained in the rust preventive agent and the amount of the alkylene oxide adduct of the cyclic monoamine (b).

[0021] Preferred alkylene oxide adducts (B) include, for example, PO 1-8 mol adducts of cyclohexylamine, PO 1 mol EO 1 mol adduct of cyclohexylamine, PO 2 mol EO 1-2 mol adducts of cyclohexylamine, PO 3 mol EO 1-3 mol adducts of cyclohexylamine, PO 4 mol EO 1-4 mol adducts of cyclohexylamine, PO 1-8 mol adducts of dicyclohexylamine, PO 1 mol EO 1 mol adduct of dicyclohexylamine, PO 2 mol EO 1-2 mol adducts of dicyclohexylamine, PO 3 mol EO 1-3 mol adducts of dicyclohexylamine, PO 4 mol EO 1-4 mol adducts of dicyclohexylamine, and the like.

[0022] Examples of the method for obtaining the salt (AB) of the aliphatic polyvalent carboxylic acid (A) and the alkylene oxide adduct (B) include, for example, (i) a method of mixing the (A) and the (B) as they are, (ii) a method of mixing the (A) and the (B) each dissolved or dispersed in water, a hydrophilic organic solvent, or a mixed solvent of water and a hydrophilic organic solvent, and (iii) a method of adding and mixing the (A) and the (B) to water, a hydrophilic organic solvent, or a mixed solvent of water and a hydrophilic organic solvent.

[0023] Examples of the hydrophilic organic solvent (which dissolves 10 g or more in 100 g of water at 25°C) include methanol, ethanol, isopropyl alcohol, acetone, methyl ethyl ketone, ethylene glycol, diethylene glycol, and tetrahydrofuran.

[0024] When mixing, a mixing device may be used, and examples of the mixing device include stirrers and dispersers. Examples of the stirrer include mechanical stirrers and magnetic stirrers. Examples of the disperser include homogenizers, ultrasonic dispersers, ball mills, and bead mills. There are no restrictions on the temperature and time during mixing, and they can be appropriately determined according to the production scale, equipment, etc. For example, when the production scale is about several kg, it is preferably about 0.1 to 5 hours at 5 to 40°C.

[0025] The molar ratio (B / A) of the alkylene oxide adduct (B) to the aliphatic polycarboxylic acid (A) is preferably from 50 / 50 to 90 / 10, more preferably from 60 / 40 to 80 / 20.

[0026] <Water-based rust inhibitor> The rust inhibitor of the present invention may be diluted with water and used as a water-based rust inhibitor. From the viewpoints of flammability, safety, or the impact on the environment, a water-based rust inhibitor is preferred.

[0027] The total content of the aliphatic polycarboxylic acid (A), the alkylene oxide adduct (B), and the salt (AB) in the water-based rust inhibitor is preferably from 0.01 to 1.0% by weight, more preferably from 0.05 to 0.5% by weight, based on the weight of the water-based rust inhibitor, from the viewpoint of long-term rust prevention performance.

[0028] The water-based rust inhibitor may contain the hydrophilic organic solvent in addition to the rust inhibitor of the present invention and water.

[0029] The pH (25°C) of the water-based rust inhibitor is preferably from 5 to 10, more preferably from 7 to 10, and particularly preferably from 8 to 9, from the viewpoint of rust prevention performance of aluminum. The pH can be measured by the glass electrode method in accordance with the method described in JIS Z8802.

[0030] <Oil-based rust inhibitor> When applying the rust inhibitor of the present invention to a metal, it may be diluted with oil and used as an oil-based rust inhibitor.

[0031] The total content of the aliphatic polycarboxylic acid (A), the alkylene oxide adduct (B), and the salt (AB) in the oil-based rust inhibitor is preferably from 0.01 to 1.0% by weight, more preferably from 0.05 to 0.5% by weight, based on the weight of the oil-based rust inhibitor, from the viewpoint of long-term rust prevention performance.

[0032] Examples of the oil include mineral oils (e.g., paraffinic or naphthenic mineral oils obtained by appropriately combining one or more purification means such as solvent dewaxing, solvent extraction, hydrocracking, solvent deoiling, catalytic deoiling, hydrorefining, sulfuric acid washing, and clay treatment to the lubricating oil fraction obtained by atmospheric distillation and vacuum distillation of crude oil), synthetic oils (polyolefins, polyalkylene glycol oils, ester oils, etc.).

[0033] In the rust preventive agent of the present invention, since (A) is an aliphatic polycarboxylic acid and the PO ratio in the alkylene oxide of the alkylene oxide adduct (B) of the cyclic monoamine (b) is 50 mol% or more, the adsorption power to iron and non-ferrous metals is extremely high, and a uniform rust preventive film can be formed on the metal surface even in a small amount. Therefore, it is presumed that the rust preventive agent of the present invention exhibits high adsorption power to a wide range of metal members (e.g., iron, copper, aluminum, etc.), has excellent shielding power against water and oxygen, and can exhibit extremely excellent rust prevention and corrosion prevention performance even in a small amount.

[0034] The rust preventive agent of the present invention can be applied to a wide range of metal members, and can be used for, for example, iron, copper, aluminum, brass, magnesium, etc., and is particularly effective for iron, copper, and aluminum among these.

Examples

[0035] The present invention will be further described by the following examples, but the present invention is not limited thereto.

[0036] <Production Example 1> 99 parts by weight (reagent manufactured by Kanto Chemical Co., Inc., purity 100%) (1 mol part) of cyclohexylamine was charged into an autoclave equipped with a temperature control device, and 58 parts by weight (1 mol part) of PO charged into a pressure-resistant dropping funnel was dropped while controlling the reaction temperature to be maintained at 140 to 150°C, and then stirred at 145°C for another 2 hours to cause a reaction. Then, after cooling to 80°C, dehydration was carried out by reducing the pressure to 600 Pa or less to obtain 157 parts by weight of a cyclohexylamine PO 1 mol adduct.

[0037] <Production Example 2> A cyclohexylamine PO 2 - mole adduct was obtained in the same manner as in Production Example 1, except that 58 parts by weight (1 mole part) of PO was replaced with 116 parts by weight (2 mole parts) of PO.

[0038] <Production Example 3> A cyclohexylamine PO 6 - mole adduct was obtained in the same manner as in Production Example 1, except that 58 parts by weight (1 mole part) of PO was replaced with 348 parts by weight (6 mole parts) of PO.

[0039] <Production Example 4> A PO 1 - mole EO 1 - mole adduct of cyclohexylamine was obtained in the same manner as in Production Example 1, except that 58 parts by weight (1 mole part) of PO was replaced with 58 parts by weight (1 mole part) of PO and 44 parts by weight (1 mole part) of EO.

[0040] <Production Example 5> A PO 4 - mole EO 4 - mole adduct of cyclohexylamine was obtained in the same manner as in Production Example 1, except that 58 parts by weight (1 mole part) of PO was replaced with 232 parts by weight (4 mole parts) of PO and 176 parts by weight (4 mole parts) of EO.

[0041] <Production Example 6> A PO 3 - mole EO 1 - mole adduct of cyclohexylamine was obtained in the same manner as in Production Example 1, except that 58 parts by weight (1 mole part) of PO was replaced with 174 parts by weight (3 mole parts) of PO and 44 parts by weight (1 mole part) of EO.

[0042] <Production Example 7> A PO 4 - mole EO 1 - mole adduct of cyclohexylamine was obtained in the same manner as in Production Example 1, except that 58 parts by weight (1 mole part) of PO was replaced with 232 parts by weight (4 mole parts) of PO and 44 parts by weight (1 mole part) of EO.

[0043] <Production Example 8> A PO 1 - mole adduct of dicyclohexylamine was obtained in the same manner as in Production Example 1, except that 99 parts by weight of cyclohexylamine was replaced with 181 parts by weight (1 mole part) of dicyclohexylamine (reagent manufactured by Tokyo Chemical Industry Co., Ltd., purity > 99%).

[0044] <Comparative Production Example 1> An EO 1-mole adduct of cyclohexylamine was obtained in the same manner as in Production Example 1, except that 58 parts by weight (1 mole part) of PO was replaced with 44 parts by weight (1 mole part) of EO.

[0045] <Comparative Production Example 2> An EO 6-mole adduct of cyclohexylamine was obtained in the same manner as in Production Example 1, except that 58 parts by weight (1 mole part) of PO was replaced with 264 parts by weight (6 mole parts) of EO.

[0046] <Comparative Production Example 3> An EO 3-mole PO 1-mole adduct of cyclohexylamine was obtained in the same manner as in Production Example 1, except that 58 parts by weight (1 mole part) of PO was replaced with 132 parts by weight (3 mole parts) of EO and 58 parts by weight (1 mole part) of PO.

[0047] <Comparative Production Example 4> An EO 1-mole adduct of dicyclohexylamine was obtained in the same manner as in Production Example 8, except that 58 parts by weight (1 mole part) of PO was replaced with 44 parts by weight (1 mole part) of EO.

[0048] <Examples 1 to 11 and Comparative Examples 1 to 5> The aliphatic polyvalent carboxylic acid (A) and the alkylene oxide adduct (B) described in Tables 1 to 2 were mixed at the molar ratios described in Tables 1 to 2 and made into a neutralized salt to produce rust preventives (X-1) to (X-11) and (Comparative X-1) to (Comparative X-5). Further, the concentration of the rust preventive was diluted to 0.05% by weight with tap water and uniformly mixed to obtain the aqueous rust preventives (Y-1) to (Y-11) of the present invention and the comparative aqueous rust preventives (Comparative Y-1) to (Comparative Y-5). The pH of the obtained aqueous rust preventive was finely adjusted to 9.0 by adding a small amount of the aliphatic polyvalent carboxylic acid (A) or the alkylene oxide adduct (B). The pH measurement was carried out in accordance with the method described in JIS Z8802 at 25°C using a pH meter (manufactured by HORIBA, "Desktop pH Meter F-71").

[0049]

Table 1

[0050]

Table 2

[0051] <Evaluation> The evaluation of rust prevention property was carried out as follows according to the corrosion test described in "6.9 Metal Corrosion Test Method" of JIS K2241 using the aqueous rust preventives prepared in the examples and comparative examples.

[0052] Each metal test piece was polished using waterproof paper (particle size 320A, manufactured by Sumitomo 3M Limited) and water, and then each strip-shaped test piece [steel plate {steel plate with a length of 76 mm, a width of 12 mm, and a thickness of 2 mm, SPCC described in JIS G3141 (cold-rolled steel plate)}, copper plate {copper plate with a length of 75 mm, a width of 12 mm, and a thickness of 2 mm, C1100P described in JIS H3100}, aluminum plate {aluminum plate with a length of 75 mm, a width of 12 mm, and a thickness of 2 mm, A1050P described in JIS H4000}] washed with toluene and acetone was placed in a test tube (inner diameter 15 mm, height 130 mm), and 10 ml of each aqueous rust preventive was poured therein, and the test piece was semi-immersed. The test tube was sealed, temperature-controlled at 25°C, and left for 48 hours. After 48 hours, the test piece was taken out, washed with water and dried, and the surface changes before and after the test were visually observed and evaluated according to the following evaluation criteria. Also, the weight was measured with an electronic balance (manufactured by METTLER, AE-240), and the weight change (mg / cm 2 ) = {(weight of the strip-shaped test piece before treatment with the aqueous rust preventive) - (weight after treatment with the aqueous rust preventive and drying)} / (surface area of the strip-shaped test piece) was calculated and evaluated. The smaller the weight change, the better the rust prevention property. ◎: There is no change at all compared with before the test or it has almost the same color tone and gloss. ○: Slight changes can be seen compared with before the test. △: Discoloration is significant compared with before the test, but general corrosion and pitting corrosion are not observed. ×: There is general corrosion, pitting corrosion, etc. regardless of the presence or absence of discoloration.

[0053] From the results in Tables 1 and 2, it can be seen that when the rust inhibitor of the present invention is used, the changes in the appearance and mass of all test pieces of iron, copper, and aluminum are small, indicating that it has excellent rust prevention performance for a wide range of metal members (e.g., iron, copper, aluminum).

Industrial Applicability

[0054] The rust inhibitor of the present invention can be applied to a wide range of metal members, for example, it can be used for iron, copper, aluminum, brass, magnesium, etc. Among these, it is particularly effective for iron, copper, and aluminum. Further, it is particularly useful as a rust inhibitor for metal parts in which an iron member and a non-ferrous metal member (e.g., copper, aluminum, etc.) are combined.

Claims

1. A rust preventive agent containing a salt (AB) of an aliphatic polycarboxylic acid (A) and an alkylene oxide adduct (B) of a cyclic monoamine (b), wherein the ratio of propylene oxide in the alkylene oxide constituting the alkylene oxide adduct (B) is 50 mol% or more.

2. The rust preventive agent according to Claim 1, wherein the aliphatic polycarboxylic acid (A) has 4 to 22 carbon atoms.

3. The rust preventive agent according to Claim 1 or 2, wherein the average number of moles of alkylene oxide added per molecule in the alkylene oxide adduct (B) is 1 to 8 moles.

4. The rust preventive agent according to Claim 1 or 2, wherein the cyclic monoamine (b) is a saturated cyclic monoamine having 6 to 12 carbon atoms.

5. An aqueous rust preventive agent containing the rust preventive agent according to Claim 1 or 2 and water, wherein the pH (25 ° C) of the aqueous rust preventive agent is 5 to 10.

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