JPS6252030B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a water-soluble film-forming rust inhibitor for metals that comes into contact with water. More specifically, the present invention relates to a water-soluble film-forming rust preventive agent that is effective against both iron-based and copper-based metals that come into contact with water. Conventionally used iron-based rust preventives include sodium nitrite, phosphorus-based compounds, and chromium-based compounds, but these rust preventives are known to be carcinogenic, such as sodium nitrite, and chromium ions. toxicity,
Its use is being restricted due to pollution problems such as red tide caused by phosphorus compounds. However, no water-soluble rust inhibitor for iron-based rust that is as effective as sodium nitrite has yet been provided. In addition, sodium nitrite is not an effective rust preventive agent for copper-based metals, is inconvenient for combinations of iron-based metals and copper-based metals, and has poor sustainability. On the other hand, the disadvantage is that the lifespan is extremely short. Furthermore, although sodium salts of benzotriazole and mercaptobenzothiazole are effective rust preventive agents for copper-based metals, they have a drawback in that they are ineffective against iron-based metals. In view of these drawbacks of conventional products, the present invention has been made through intensive research and has resulted in the development of a rust preventive agent that is extremely effective against iron and copper metals. That is, carbon number 6
The product of the present invention, which consists of ~12 saturated aliphatic dicarboxylic acids and polyamide amine, can be easily dissolved in water by adding it to water, and does not exhibit any side effects such as toxicity. It has also been found that this is a rust preventive agent that exhibits extremely effective rust preventive effects on both iron-based and copper-based metals over a long period of time. Examples of the saturated aliphatic dicarboxylic acid having 6 to 12 carbon atoms used in the present invention include adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanoic acid, and dodecanoic acid. Further, the polyamide amine used in the present invention is generally obtained by a method of condensing a polymerized fatty acid and a diamine. That is, it is obtained by reacting dimer acid, which is a dimer of fatty acids such as soybean oil, tung oil, and tall oil, with an alkyl polyamine such as ethylenediamine, diethylenetriamine, and triethylenetetramine, and has an active amino group. It is generally expressed by the following formula. H[-HN( _-CH2 - _CH2- NH) _{-n CH2- CH2-} NHCO-R-CO] _-o NH( _{-CH2 -} CH2NH) _{-n CH2} - _CH2 - _NH2 However, R is n and m represent integers of 1 or more. This polyamide amine has conventionally been used mostly as an epoxy resin curing agent, has low toxicity and volatility, is easy to handle, and is known to have some rust-preventing effect by itself and to be an inhibitor under acidic conditions. However, it cannot be said that it has excellent anti-rust properties. When using the rust preventive agent of the present invention, it is possible to further enhance the effect by using it in combination with other known additives (rust preventive agents, stabilizers, etc.) if necessary. Next, the present invention will be explained with reference to Examples. The following compositional blend of saturated aliphatic dicarboxylic acid and polyamidoamine (product of the present invention) is synthesized in ethyl alcohol of a weight equal to the mixed weight of the saturated aliphatic dicarboxylic acid and polyamidoamine while stirring with heating. The amount added is the concentration of saturated aliphatic dicarboxylic acid and polyamide amine, and does not include the weight of alcohol. The polyamide amine used was a commercially available product, and its description is shown in Table 1.

【table】

【table】

[Table] City water with the following water quality was used as the test liquid, a prescribed chemical (product of the present invention) was added to the test liquid, and a test piece (steel plate SPCC, 50 x 10 x 1 mm copper plate) was added to the test liquid.
TUCuPl, 50 x 10 x 1 mm) and tested at 50°C for 7 days in a shaking constant temperature bath. The degree of corrosion (mdd = corrosion loss (mg)/number of test days (day) x test piece surface area (dm ² )) is calculated from the amount of weight loss of the test piece before and after the test. The test results obtained are shown in Table 2. [Water quality analysis values of city water] PH (at 23℃) 7.2 Electrical conductivity (μs/cm) 133 M-Alkalinity (CaCO ₃ ) (ppm) 28 Total hardness (CaCO ₃ ) (ppm) 36 Chlorine ion (C1 ^- ) (ppm) 15 Total iron (Fe) (ppm) 0.34

【table】

[Table] From the above test results, it was confirmed that the rust preventive agent according to the present invention exhibits an excellent rust preventive effect on both iron-based and copper-based metals. In addition, the rust preventive of the present invention has a high boiling point, has little odor, is water-soluble, and has low toxicity, so it can be used in cooling systems of chemical plants that come into contact with water, steam production equipment, etc.
It can be used as a rust preventive agent for heating systems, antifreeze, and oil, and can be applied to exposed areas indoors, and can be used for a wide range of iron-based and copper-based metals. Effective for combinations of iron and copper metals.

Claims (1)

[Claims] 1 a saturated aliphatic dicarboxylic acid having 6 to 12 carbon atoms;
A rust preventive agent characterized by consisting of polyamide amine.