JPS6019799B2 - Metal surface treatment agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a metal surface treatment agent containing nitrite or nitrite.

Conventionally, nitrous acid or nitrites (hereinafter referred to as nitrites) have been widely blended into chemicals used for surface treatment of metals, such as abrasives, rust preventives, and cleaning agents.

However, these nitric acids react with the amines that are simultaneously blended in the metal surface treatment agent to form N-nitroso compounds, which exhibit extremely high dust-generating properties. The development of drugs is urgently needed. However, on the other hand, it is an undeniable fact that there are still fields where the use of nitrites is unavoidable, and there is a need for some kind of countermeasure, even if only temporarily, to suppress carcinogenesis and toxicity caused by nitrites.

The present inventors investigated a substance that has no adverse effect on metal surface treatment (and is not harmful to the human body, and has the effect of suppressing N-nitroso compounds due to the reaction between nitrites and amines), and discovered that polyphosphoric acid They discovered that salt has a remarkable effect and completed the present invention.

That is, the present invention relates to a metal surface treatment agent containing nitrite and/or nitrite and polyphosphate.

In the present invention, the polyphosphate is selected from sodium tripolyphosphate, sodium tritaphosphate, and ultrasodium phosphate.

It is thought that these polyphosphates react with amines and inhibit the formation of N-nitroso compounds due to the reaction between amines and nitrites. Many metal surface treatment agents, especially those that use a large amount of nitric acid and amines together, such as abrasives and cutting agents, may form nitroso compounds in the treatment agent. PolyJ phosphate is used in an equivalent amount, preferably 2 equivalents or more, of the amine used.
Polyphosphoric acid may be simply mixed into a treatment agent with nitric acid or amines, but since many polyphosphoric acids are gradually hydrolyzed by water, it is also possible to react with the amines used before adding the polyphosphoric acid. good. In particular, cyclic polyphosphoric acid, ultraphosphoric acid, etc. are extremely unstable in an aqueous solution, so it is preferable to react them with an amine in advance. A typical use in this invention is as a grinding or cutting agent.

As mentioned above, cutting and abrasive agents often contain amines, and the risk of carcinogenicity has been particularly pointed out. In cutting and abrasive agents using polyphosphate as in the present invention, N-
Not only is the formation of nitroso compounds significantly suppressed, but the cutting or grinding effect itself is improved. This will be explained below by giving examples.

Example 1 25mM dimethylamine hydrochloride aqueous solution, 25mM sodium nitrite solution and condensed sodium phosphate aqueous solution (p
H3.5 buffer solution) in a volume ratio of 1:1:2
The test solution is prepared by mixing at the following ratio and reacting for a predetermined period of time.

Add 5 parts of n-butanol, 1 part of sulfanilamide, 1 part of n-naphthylethylenediamine, and 3 parts of hydrochloric acid:n-butanol solution (1:2) to test solution 5,
-65oo for 50 minutes, and after distilling off the extraction solvent,
Heat at 00:00 for 18 minutes to develop color.

The resulting solution was diluted with n-butanol to 55%
2. Measure the absorbance of the kite mountain. Figure 3 shows N in various solutions.
- Changes in the amount of dimethylnitrosamine produced (absorbance) (vertical axis) over time (reaction temperature 370, in pH 3.5 buffer) are shown.

In the figure, 1, 2 and 3 are 0.9M sodium trimetaphosphate solution and 50m
The cases of M sodium tripolyphosphate solution and 1.5% sodium ultraphosphate solution are shown, and 4 shows the case of no condensed phosphate added. As is clear from the above table, it is understood that polyphosphoric acid has a remarkable ability to inhibit the formation of N-nitrosodimethylamine. Example 2 Aqueous solution of sodium nitrite and trietanoamine (JIS
The cutting effects of a cutting fluid containing polyphosphoric acid and a cutting fluid containing polyphosphoric acid will be compared.

Cutting fluid formulation A: Sodium nitrite 0.5% aqueous solution (Reference example: Trietanolamine 0.5%) B: Sodium nitrite 0.5% Trietanoamine 0.5% aqueous solution Sodium tripolyphosphate 0.5 % C: Sodium nitrite 0.5% Trietanoamine 0.5% Aqueous solution Sodium hexametaphosphate 0.5% Grinding conditions: Grinding machine Internal grinding wheel WA80KV Material SUJ-2 Torishiro 0.3 rib rotation spindle 120 Pm grinding wheel 2000 Pm The test results are shown in Table-1.

Table 1 (The rust prevention properties are based on the results obtained by observing rust after 72 hours had elapsed after dipping dry cutting chips from castings, draining the liquid, and placing them in a petri dish.) This shows that the addition of acid not only improves grindability, but is itself useful as a rust inhibitor.

Depending on the type of polyphosphate, some types are difficult to dissolve in nitrite and amine mixtures, so a bleached nitrate-based abrasive that does not contain amines may be used and polyphosphoric acid may be added to the solution used.

[Brief explanation of the drawing]

FIG. 1 shows the effect of condensed phosphates on inhibiting the formation of N-nitroso compounds. The vertical axis shows absorbance and the horizontal axis shows time. 1 indicates sodium trimetaphosphate, 2 indicates sodium tripolyphosphate, 3 indicates sodium ultraphosphate, and 4 indicates no addition of condensed phosphoric acid. Figure 1

Claims (1)

[Claims] 1. A metal surface treatment agent containing nitrous acid and/or a nitrite and a polyphosphate selected from sodium trimetaphosphate, sodium tripolyphosphate and sodium ultraphosphate. 2. The treatment agent according to item 1, wherein the metal surface treatment agent is a cutting or grinding agent. 3. The treatment agent according to item 1, wherein the metal surface treatment agent is a rust preventive agent.