JPH01246377A - Composition of anticorrosive agent for metal - Google Patents

Abstract

PURPOSE:To provide a composition of anticorrosive agent for metal combining high corrosion-preventing capacity with superior scale inhibiting capacity by blending molybdate and phytic acid or its salt with specific phosphonic acid or its salt. CONSTITUTION:Molybdate and phytic acid or its salt are blended with water-soluble phosphonic acid, such as aminotriethylenephosphonic acid, having <=4C alkyl group and containing one or more phosphonoalkyl groups substituted by amino group, hydroxyl group, or carboxyl group in a molecule or its salt. Further, it is desirable that phytic acid or its salt is blended in a proportion of 1-50 pts.wt. based on 100 pts.wt. of the above composition. By the above constitution, the low-toxicity and low-pollution anticorrosive agent for metal showing superior corrosion-preventing effect even in concentrated and highly corrosive water and having scale-inhibiting capacity can be obtained.

Description

[Detailed Description of the Invention] The present invention provides a metal corrosion inhibitor, particularly a metal corrosion inhibitor that exhibits excellent corrosion protection effects on iron, copper, zinc, aluminum, and their alloys in water, and is highly safe. be.

<Prior art and its problems> Conventionally, inorganic and organic substances such as chromates, nitrites, and condensed phosphates have been used as anticorrosive agents to prevent damage caused by corrosion of metals in water passage parts of various cooling systems and air conditioning systems. Those containing v11'IFl as a main ingredient such as amines and carboxylic acid salts are used.

Chromate-based anticorrosive agents have been widely used because they are inexpensive and have excellent anticorrosive effects. Regulations regarding its use have been strengthened. Although nitrites have a great anticorrosion effect, they are also highly toxic and have the same problems as chromates.Furthermore, condensed phosphates have a relatively weak anticorrosion effect and generate phosphates through hydrolysis, so wastewater containing phosphates cannot be treated. The inflow of water causes rivers and rivers to become eutrophic, causing abnormal growth of algae, which also leads to pollution. In this way, all of the conventionally used practical corrosion inhibitors cause environmental damage due to wastewater and do not meet the demands of modern pollution prevention.On the other hand, removing harmful components by treating wastewater requires a large amount of equipment Investment is required and economic efficiency is significantly reduced. Organic anticorrosive agents such as amines and carboxylic acids are generally W! Compared to mechanical anticorrosives, the anticorrosion effect is weaker, and there are also pressures when handling them to avoid causing bad odors or skin damage. Therefore, there is a need for a low-toxicity, low-pollution, and highly safe metal corrosion inhibitor that can replace conventional products.

In addition, recently, in addition to the decline in the quality of water resources and the increasing shortage of water, measures to reuse water by recycling cooling water, etc. have been strongly discouraged in order to comply with strict wastewater regulations. , corrosive ions and scale-forming components in service water frequently cause corrosion and scale formation in water flow systems due to R shrinkage, and pitting corrosion is also occurring in materials that have traditionally been trusted as T1 materials with relatively high corrosion resistance. This has become a serious problem, and there is a desire for an anticorrosive agent that has a stronger anticorrosion effect and also has an anti-scaling effect.

<Purpose and Structure of the Invention> The inventors have developed a low-toxicity, low-pollution product that does not cause environmental pollution or problems in handling, and has an excellent anti-corrosion effect even in highly corrosive water. As a result of research aimed at developing a metal corrosion inhibitor that has anti-scaling properties as well as anti-scaling properties, three components were found, including a certain type of phosphonic acid or its salt (hereinafter the same), phytic acid or its salt (hereinafter the same), and molybdate. It has been discovered that the composition of this system not only exhibits an extremely high anti-corrosion ability that cannot be predicted from the effects of the individual components, but also has an extremely excellent anti-scaling ability. Both phosphocari-1 phytic acid and molybdate used in the present invention are of low toxicity, do not require measures against environmental pollution caused by wastewater or special wastewater treatment facilities, and do not cause any problems in handling. The formulation results in a metal corrosion inhibitor that fully meets the objectives of the invention.

Certain phosphonic acids are used as low-toxicity anticorrosive agents, but they do not have sufficient anticorrosion effects when used alone.For example, organic amines, surfactants, condensed phosphates, organic acids, and nitrous acid (salts) Attempts have been made to improve corrosion resistance by combining known corrosion inhibitors such as , moly, azonate, and chromate, but nothing has yet been found that satisfies both improved corrosion protection and low pollution properties. .

The anticorrosive agent of the present invention, which consists of three components of phosphonic acid, phytic acid, and molybdate, is characterized by the addition of phytic acid as an active ingredient. Moreover, a strong anticorrosive effect far exceeding that obtained when phosphonic acid and molybdic acid are used in one well can be obtained. In addition, a two-component combination of phosphonic acid and phytic acid, or molybdate and phytic acid does not have the same effect; only a three-component combination of phosphonic acid, phytic acid, and molybdate can produce such a strong anticorrosion effect. Appear.

Phytic acid: Although it is known to have a weak anticorrosion effect, it is used as a metal corrosion inhibitor for water flow equipment such as cooling systems and air conditioning systems. It is surprising that the effect exceeds that of the previous one, and is thought to be based on the unique synergistic effect of phytic acid.

Further, experimental results have revealed that the anticorrosive agent of the second invention is effective against pitting corrosion of scale and copper, which are particularly problematic in highly concentrated water systems.

Therefore, the second invention provides a metal anticorrosive agent containing phosphonic acid, phytic acid, and molybdenum I salt as essential components; The present invention relates to a metal corrosion inhibitor characterized by containing water-soluble phosphonic acid or its salt, phytic acid or its salt, and molybdate containing phosphonoalkyl groups in the molecule, and is used in cooling systems and air conditioning systems. Iron, steel, zinc, and aluminum in the water passage part The alkyl group used in this invention has 49 carbon atoms or less and has one or more phosphonoalkyl groups substituted with an amino group, a hydroxyl group, or a carboxyl group in the molecule. Examples of water-soluble phosphonic acids include aminotrimethylenephosphonic acid, ethylenediaminetetramethylenephosphonic acid, 1-hydroquinethylidene-1,1-
Diphosphonic acid, 1,1-dihydroxyethane diphosphonic acid, hydroxypropylidene diphosphonic acid, 2-phosphonopropionic acid, 1-o, sulfonobroban-2,3-dicarboxylic acid, 2゜2-cyphosphonobutane-3.4 -dicarbonate, and their salts such as alkali metal salts, ammonium salts, and organic amine salts can also be used. Preferred organic amines include ethylamine, diethylamine, propylamine, propylene diamine, ethanolamine, and ethyl xylamine. molybdenum 7
Lithium salts, sodium salts, potassium salts and ammonium salts are preferred.

Phytic acid, also known as myo-inositol hexaphosphate, is a polybasic acid that widely exists in the plant world. You can also use it. Amines include ethylamine, diethylamine, propylamine, propylene diamine, ethanolamine,
Any water-soluble amine salt such as diethylhexylamine may be used. As the raw materials for blending the individual components, either powder or solution may be used, and the resulting anticorrosive composition may be in the form of powder or i''f7fi depending on the raw materials.

Therefore, the anticorrosive composition of the present invention includes both powder and droplet forms; however, in the following explanation, unless otherwise specified, descriptions regarding the composition and concentration will be based on the combination of solid components. The amount also represents the concentration.

Phytic acid should be blended in an amount of 1 to 50 parts by weight per 100 parts by weight of the anticorrosive composition.If it is less than 1 part by weight, no effective synergistic effect will be observed, and if it is added in excess of 50 parts by weight. However, the effect is not greatly enhanced.

Although it is desirable to have the above composition, this does not mean that the synergistic effect of phytic acid cannot be observed in other compositions as well.

The effective 1 degree of the composition of this invention in a water-flowing system varies depending on the conditions of use such as the quality and temperature of the water used, but in normal freshwater-based water-flowing equipment, it is at least 1 ppm or more, and in cases where the composition is highly concentrated and has a large tendency to corrode. Approximately several thousand ppm is required. It is less affected by the flowing state of water, and good anticorrosion effects can be obtained not only in flowing water but also in still water. There is no restriction on pH during use, and it is widely compatible with normal operating conditions of cooling systems and air conditioning systems. Therefore, all salts do not have to be neutral salts, but can also be used as a mixture containing some free acids, and the pH can be adjusted depending on the conditions of the water flow system. If necessary, auxiliary components commonly used as additives for water treatment agents, such as dispersants such as polysodium methacrylate, and disinfectants such as benzotriazole, can also be added.

This will be explained in detail below using examples.

<Examples> Examples 1 to 8 Phosphosnic acid, phytic acid, and sodium molybdate were blended in the proportions shown in Table 1 and thoroughly mixed to prepare anticorrosive compositions of Examples 1 to B.

Comparative Examples 1 to 8 Phytic acid was removed. Phosphonic acid and sodium molybdate were mixed in the same proportions as in Examples 1 to 8, and Comparatives 411 to 8 were prepared.
8 compositions were prepared.

The compositions of Examples and Comparative Examples were measured for corrosion prevention ability, scale prevention ability, and pitting corrosion prevention ability, and the results are shown in Tables 2, 3, and 4, respectively.

Measurement method Corrosion prevention ability: NaCl, MgSO4, CaCl2 each 50
30 m*
soft ¥x (,1155541), phosphorus deoxidized steel (, JIS
C-1220P), zinc (,,11511-4321
Type 1) or aluminum (, JIS AlF2-0
) specimen ft was immersed and kept at 50±5°CC160RP on Saturdays and Sundays, then taken out and dried, dissolved the anticorrosion agent 10B of the example in Dry 1, adjusted the FA to Pl+ to 8.5, and stirred at room temperature and 60 RPM for 1 hour. Let stand for 20 hours. After filtering 1! Ca in liquid
The content was measured, and the residual rate of dissolved calcium was taken as the scale prevention ability of the sample anticorrosive agent.

Pitting corrosion prevention effect: NaCl, Mg5Oa, CaCl2
each) OOmg/ and anticorrosion agent of Example or Comparative Example +5
A phosphorus-deoxidized copper specimen (the same as that used to measure anticorrosion ability) was immersed in a solution containing 0.111 g/L and held at room temperature and 60 PPM for 60 days, then taken out, dried, and the surface was observed using a metallurgical microscope. . A case where almost no pitting corrosion was observed was judged as "absent", and a case where pitting corrosion was clearly observed was judged as "present".

<Effects of the Invention> The above measurement results show that the anticorrosive effect is significantly enhanced by adding phytic acid to phosphonic acid and molybdic acid, and the occurrence of pitting corrosion and scale can also be prevented. The anticorrosive composition has low pollution and excellent anticorrosion properties that are not found in Kurushima, and in addition, the highly corrosive water that has been treated with JPii has a margin of less than EDTP ethyl nondiamine tetramethylene phosphonic acid DEDP 1 .1-Hydroxyethanediphosphonic acid PBDC2,2-diphosphonbutane-3,4-dicarboxylic acid All numbers represent parts by weight Table 2 Table 3 Table 4 Patent applicant Rin Kagaku Kogyo Co., Ltd.

Claims (2)

[Claims] (1) The number of carbon atoms in the alkyl group is 4 or less, and an amino group,
Metal corrosion protection characterized by blending a molybdate and phytic acid or a salt thereof with a water-soluble phosphonic acid or a salt thereof containing in the molecule one or more phosphonoalkyl groups substituted with a hydroxyl group or a carboxyl group. agent composition (2) Phytic acid or its salt is a metal corrosion inhibitor composition 10
The metal corrosion inhibitor composition according to claim (1), which is blended in a ratio of 1 to 50 parts by weight in 0 parts by weight.