JP2007169459A - Antifreezing composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antifreezing composition which is inhibited in the corrosion of a metal. <P>SOLUTION: The composition comprises an antifreezing component, an oxycarboxylic acid salt, and a polyphosphoric acid salt. The composition shows a high effect in suppressing the corrosion of a metal. It shows excellent activity particularly even under repeated drying-wetting conditions like as natural surroundings, so that corrosion speed is lowered down to the level of water or lower. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an antifreezing agent composition used as an antifreezing agent, a snow melting agent, a dustproofing agent or the like.

In snowy and cold regions, it is important to prevent snow melting and freezing on the road surface in order to ensure traffic safety and road environment in winter. There is a method of providing road snow melting facilities such as road heating and snow pipes as a measure to prevent snow melting and freezing on the road surface, but it is limited to some due to the disadvantage of high construction costs.
On the other hand, the application of the antifreezing agent can be applied to a wider range of road management because it does not require any special capital investment.
Antifreezing agents include chlorides such as calcium chloride, sodium chloride, magnesium chloride, urea, CMA (based on calcium acetate and magnesium acetate) and KAC (based on potassium acetate solution) Acetate is sold.
Of these, chlorides such as calcium chloride, sodium chloride, and magnesium chloride are most widely used in Japan from the viewpoints of economy and antifreezing effect.
However, chloride is highly corrosive to metals, and when sprayed on the road, it corrodes metal parts such as automobile bodies and road signs, so the addition of a rust inhibitor is essential.
As a rust preventive agent in the case of using a chloride, a carboxylic acid compound, a lignic acid compound, sodium nitrite, sodium tripolyphosphate, etc. are used (for example, see Patent Document 1, Patent Document 2, and Non-Patent Document 1). .)
JP 2002-60726 A JP-A-10-140130 Development Public Works Research Institute Monthly Report No. 487 December 1993 P.9-26 “On winter road surface management with anti-freezing agents in Hokkaido”

  The corrosion test is generally performed by continuous immersion. However, since the immersion state and the dry state are repeatedly performed in the natural environment, the corrosion test by the wet and dry repeated method has also been evaluated. Although the rust preventive agent mentioned above shows a rust preventive effect, it did not satisfy the rust preventive performance required in the continuous immersion test and the dry and wet repeated test.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide an antifreezing agent composition that suppresses corrosion of metals.

  The gist of the present invention resides in an antifreeze composition containing an oxycarboxylate and a polymerized phosphate as a rust preventive component in addition to an antifreeze component.

  The antifreezing agent composition of the present invention has a great effect of suppressing metal corrosion. In particular, it exhibits an excellent effect even under repeated wet and dry conditions simulating the natural environment, and the corrosion rate is equal to or lower than that of water.

The antifreezing agent composition of the present invention contains an antifreezing component, an oxycarboxylate and a polymerized phosphate.
Various components used as a known antifreezing agent can be applied to the antifreezing component. For example, chlorides such as sodium chloride, calcium chloride, and magnesium chloride are listed.
The present invention is characterized in that an oxycarboxylate and a polymerized phosphate are used in combination as a rust preventive component. By combining these two components, even when a highly corrosive sodium chloride, calcium chloride, magnesium chloride or the like is used, rust prevention performance is effectively exhibited. In particular, it exhibits an excellent effect even under repeated dry and wet conditions simulating the natural environment, and the corrosion rate can be suppressed to a level equal to or lower than that of water.
The oxycarboxylate used in the present invention is at least one selected from the group consisting of alkali metal salts or alkaline earth metal salts such as lactic acid, citric acid, tartaric acid, gluconic acid, heptonic acid and malic acid.
The polymerized phosphate used in the present invention is composed of alkali metal salt or alkaline earth metal salt such as pyrophosphoric acid, tripolyphosphoric acid, tetraphosphoric acid, trimetaphosphoric acid, hexametaphosphoric acid, and a part of alkali metal or alkaline earth metal. It is at least one selected from the group consisting of hydrogenated polymerized phosphates.
It is desirable that the rust preventive component is used in an amount of 50 parts by mass or less as a total of the rust preventive component with respect to 100 parts by mass of the main antifreeze agent from an economical viewpoint. Moreover, it is desirable to use 0.1 mass part or more as a total of an antirust component with respect to 100 mass parts of main antifreeze agents by the required antirust performance.
Moreover, it is desirable that the use ratio of oxycarboxylate and polymerized phosphate (oxycarboxylate / polymerized phosphate) is 1/99 to 99/1. If the proportion of oxycarboxylate and polymerized phosphate used is outside this range, the corrosion rate exceeds that of water, and the required rust prevention effect tends not to be obtained.
In addition, since the antifreezing agent composition of the present invention does not require a volatile organic solvent (VOC), acetate, ammonium salt, etc., no bad odor is generated and the adverse effect on the global environment and human body is small.
Furthermore, since the antifreeze composition of the present invention has a high antirust effect, chlorides such as sodium chloride, calcium chloride, magnesium chloride, etc., which have high antifreeze properties but high corrosivity, can be used. These anti-freezing components are less expensive and more economical than other low-corrosion anti-freezing agents (CMA, urea, etc.).

Since the antifreezing agent composition of the present invention can be composed entirely of solids, transportation, storage, and spraying can be handled as solids.
Furthermore, each component described above is water-soluble, and the antifreezing agent composition of the present invention can be an aqueous solution, and transportation, storage, and spraying can be handled as an aqueous solution. Therefore, it can be handled as a solid or a liquid according to the use mode and the like, and the degree of freedom is high.
Moreover, it is desirable that the antifreezing agent composition of the present invention contains a pH adjuster as necessary. Examples of such a pH adjuster include at least one inorganic alkali component selected from the group consisting of alkali metal or alkaline earth metal hydroxides, carbonates, and bicarbonates. For example, there are inorganic alkali components such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and sodium hydrogen carbonate.
It is desirable to adjust the pH to a neutral range of 5 to 9 with a pH adjuster because the influence on road pavement materials and the environment can be further reduced.

  The antifreezing agent composition of the present invention may contain other components in addition to the above-described components within a range not departing from the gist of the present invention. In consideration of safety and the environment, each component can be composed only of substances permitted as food additives.

Various antifreeze compositions were prepared by dissolving solids composed of the components shown in Table 1 below in water.
The resulting aqueous solution of each antifreeze composition was tested for metal corrosion rate.
Table 2 shows a comparative example similarly tested.

[Metal corrosion rate calculation method by continuous immersion corrosion test]
(1) Cold-rolled steel plate specimens (50 × 30 × 2 mm, surface area 33.2 cm ² ) were polished with # 400 emery cloth, degreased with acetone, and dried.
(2) The test piece was suspended so as to be fully immersed in an aqueous solution of each antifreeze composition kept at 50 ° C. so that the corrosion rate was accelerated.
(3) After holding for 7 days (168 hours), the test piece was taken out, the corrosion product on the surface was removed and dried.
(4) The mass of the test piece before and after immersion was measured, and the corrosion rate was calculated by the following formula.

[Calculation method of metal corrosion rate by wet and dry repeated corrosion test]
(1) Cold-rolled steel plate specimens (50 × 30 × 2 mm, surface area 33.2 cm ² ) were polished with # 400 emery cloth, degreased with acetone, and dried.
(2) The test piece was suspended so as to be fully immersed in an aqueous solution of each antifreeze composition kept at 23 ° C.
(3) After immersion for 24 hours, the test piece was taken out and air-dried for 24 hours.
(4) After this immersion and drying were repeated for 7 days (168 hours), the test piece was taken out on the 8th day, and the corrosion products on the surface were removed and dried.
(5) The mass of the test piece before and after the cycle was measured, and the corrosion rate was calculated in the same manner as described above.

Comparative Example 1 is a target condition and shows the corrosion rate of water when no cryoprotectant is used.
Examples 1 and 2 show tests when sodium chloride is used as an antifreeze, and Examples 3 to 9 show tests when calcium chloride is used as an antifreeze. All of Examples 1 to 9 show that the corrosion rate is lower than that of Comparative Example 1 and the rust prevention performance is higher in the continuous immersion corrosion test and the wet and dry repeated corrosion test.
On the other hand, Comparative Examples 2 and 3 are cases where no rust preventive is used, indicating that the anti-freezing component containing chloride as a component is highly corrosive. Comparative Example 4 shows a case where only carboxy salt sodium gluconate is used as a rust preventive agent, and Comparative Example 5 shows a case where only polymerized sodium phosphate pyrophosphate is used as a rust preventive agent. Comparative Example 4 and Comparative Example 5 are clearly inferior to Examples 1-9 and Comparative Example 1. Therefore, it is shown that the synergistic effect of using together two types of rust preventive agents of a present Example is very high.

Claims (4)

  A cryoprotectant composition comprising an antifreeze component, an oxycarboxylate and a polymerized phosphate.   The antifreezing agent composition according to claim 1, comprising at least one inorganic alkali component selected from the group consisting of alkali metal or alkaline earth metal hydroxides, carbonates, and hydrogen carbonates as a pH adjuster. .   The antifreezing composition according to claim 1 or 2, further comprising water. The cryoprotectant composition according to claim 3, wherein the pH is in the range of 5-9.