JP2008231450A - Detergent for metal product, and detergent aqueous solution for metal product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sulphamic acid-oxycarboxylic acid based detergent which is excellent in ability of suppressing the hydrogen embrittlement of metal and the elution of metal while providing high detergency when a titanium product stuck with a calcium compound or the like as the object for cleaning is cleaned. <P>SOLUTION: The detergent for the metal product consists of a mixed solution containing sulphamic acid, citric acid, malic acid and an alkaline carbonate, wherein the blending ratio (weight ratio) among the sulphamic acid: citric acid: malic acid: alkaline carbonate is 79 to 91:7 to 3:7 to 3:7 to 3. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is a cleaning for sulfamic acid-oxycarboxylic acid-based metal products that prevents titanium from hydrogen embrittlement and metal elution when cleaning titanium and titanium alloy products to which calcium compounds are adhered. In particular, cleaning agents for metal products that maintain the cleaning effect when used as cleaning agents for titanium and titanium alloys used as aircraft parts, and suppress and reduce hydrogen embrittlement that occurs in such cases, and The present invention relates to an aqueous cleaning solution for metal products.

Titanium and titanium alloys are active metals, but the metal surface is easily passivated, and the passive film is extremely stable chemically. Unlike stainless steel, titanium and titanium alloys remain passive even in chloride and exhibit very high corrosion resistance. Titanium retains high specific strength even at temperatures up to 450 ° C., which has excellent specific strength and heat resistance among light metals, and general light alloys begin to lose strength.
For these reasons, applications are expanding in various directions. Familiar materials such as eyeglass frames, wristwatch fittings and artificial teeth, industrial materials that utilize high corrosion resistance, heat exchangers, valves, piping, synthetic towers, etc., as well as high specific strength and heat resistance. Widely used in the aerospace field.

In this way, titanium and titanium alloys are expected to diversify in the future, but hydrogen embrittlement occurs due to the formation of metal hydrides due to long-term use under high temperature and high pressure conditions and the use of strong acidic detergents. Occurs and becomes a serious problem. In other words, hydrogen embrittlement significantly reduces the specific strength performance of titanium and promotes metal degradation.
A sulfamic acid-oxycarboxylic acid type cleaning agent is known as a cleaning agent for metal containing titanium or a titanium alloy as described above. For example, the cleaning agent described in Patent Document 1 is a calcified calculus that could not be removed without using a conventional inorganic acid or inorganic alkali, compared to other conventional cleaning agents using inorganic acid or inorganic alkali.・ It is effective in removing scales attached to the inner wall of the drain pipe, and has the advantage that it can be used safely and is an environmentally friendly cleaning agent. It can be said that it is an excellent cleaning agent in that it has a high detergency and can exhibit characteristics that are somewhat excellent in the ability to suppress metal hydrogen embrittlement and metal elution.
Japanese Patent No. 3509818

However, although the cleaning agent described in Patent Document 1 (hereinafter referred to as conventional cleaning agent) can exhibit some excellent properties in the ability to suppress metal hydrogen embrittlement and metal elution, Since it was developed with priority given to the cleaning action, it cannot be said to be sufficient in terms of suppressing hydrogen embrittlement and preventing metal elution. In order to use for cleaning water pipes, etc., elution of metal titanium and hydrogen embrittlement should be solved without impairing the cleaning effect on titanium. In addition, development that considers the environmental impact of cleaning agents is essential.
Therefore, the main object of the present invention is to improve this on the basis of the above-mentioned conventional cleaning agent, while providing high cleaning power when cleaning titanium products to which calcium compounds, etc., which are objects to be cleaned are adhered, An object of the present invention is to provide a sulfamic acid-oxycarboxylic acid-based cleaning agent having an excellent ability to suppress metal hydrogen embrittlement and metal elution.

In order to achieve the above object, the cleaning agent according to the present invention comprises a mixed solution of sulfamic acid, citric acid, malic acid and alkaline carbonate, and the mixing ratio of the above sulfamic acid: citric acid: malic acid and alkaline carbonate ( The metal product cleaning agent is characterized in that the weight ratio is 79 to 91: 7 to 3: 7 to 3: 7 to 3. This provides a novel cleaning agent capable of suppressing hydrogen embrittlement and metal elution while maintaining the excellent cleaning performance of the conventional cleaning agent.
Further features of the present invention and the effects it provides will be more clearly understood based on the best mode for carrying out the invention described in detail below.

  The conventional detergent based on the detergent for metal products according to the present invention has a blending ratio (weight ratio) of sulfamic acid: citric acid: malic acid of 80 to 95:10 to 2.5 to 10 to 2. The cleaning agent for metal products according to the present invention comprises a mixed solution of sulfamic acid, citric acid, malic acid and alkaline carbonate, and the mixing ratio of the above sulfamic acid: citric acid: malic acid and alkaline carbonate The metal product cleaning agent is characterized by having a (weight ratio) of 79 to 91: 7 to 3: 7 to 3: 7 to 3. Therefore, the metal product cleaning material according to the present invention maintains the cleaning power of the conventional cleaning agent by maintaining the blend ratio of sulfamic acid, citric acid and malic acid in the conventional cleaning agent. Furthermore, by newly adding alkaline carbonates such as sodium carbonate and potassium carbonate, the elution of the metal to be cleaned can be remarkably reduced as compared with conventional cleaning agents, as will be apparent from the following test examples. The metal strength can be prevented from decreasing due to hydrogen embrittlement.

The cleaning agent according to this embodiment comprises a mixed solution of sulfamic acid, citric acid, malic acid and alkaline carbonate, and the blending ratio (weight ratio) of sulfamic acid: citric acid: malic acid and alkaline carbonate is 79. It is a metal cleaning agent which is -91: 7-3: 7-3: 7-3.
The concrete contents can be understood by the following test examples.

`` Test example ''
The test examples demonstrating the effect of the present invention and the results are described below. First, Table 1 shows the composition table of the cleaning liquid used in the test.
Here, the composition (%) indicates the composition of a detergent diluted with a 10% aqueous solution.
Of the above, the solution F to which sodium acetate has been added produces acetic acid that produces an odor affecting the environment, and the solution G to which sodium sulfide has been added is a toxic gas, hydrogen sulfide, during the preparation of the solution and during the following tests. Occurred.
Therefore, from the viewpoint of environmental protection, the solution F to which sodium acetate is added and the solution G to which sodium sulfide is added are not employed as cleaning agents.

"Test 1"
The titanium elution test was conducted using the above-described detergents A to G. The results are shown in Table 2 below.
A titanium plate (material: purity 99.85%, TP270C) of 30 mm × 50 mm × 0.5 mm is immersed in each solution of A to G under conditions of a bath temperature of 353 K (80 ° C.) and an immersion time of 24 hours. The elution amount of was measured by ICP emission spectrometry, and the elution test of titanium for each solution was performed.
F _EX.1 in Table 2 below, the amount of elution of the ratio of each solution when the elution amount resulting solution A was 1.000, F _{Ex.2 has} a scratch hardness of the solution A was 1.000 The ratio of the scratch hardness of each solution is shown. In addition, the measurement result of the pH change before and after the treatment is shown for reference.
In this way, in addition to a part of the citric acid and malic acid blending amount in the conventional cleaning agent, by adding each of the alkaline carbonate reagents of B to G in Table 1, the titanium elution amount is significantly suppressed. I found out that
Among them, the addition of B sodium carbonate showed the most remarkable effect.

"Test 2"
The dissolution ability test with respect to the shells of the cleaning agents A to G in Table 1 was conducted.
In this method, 5 g of shells attached when seawater is supplied and discharged are immersed in 100 g of solutions A to G under the conditions of a bath temperature of 298 K (25 ° C.) and an immersion time of 30 min, and the elution amount of calcium ions is determined by ICP emission spectrometry. The solution was compared for dissolution and cleaning ability.
As a result, the results shown in Table 3 below were obtained. F _EX.3 represents the ratio of the amount of elution of each solution when the result of the amount of shell elution of Solution A is 1.000.
From Test 2, it was found that the amount of shellfish (calcium salt) dissolved slightly decreased by adding an alkaline carbonate reagent instead of a part of citric acid and malic acid.
From the above tests 1 and 2, in order to comprehensively compare the amount of titanium elution and the cleaning ability judged from the amount of shells eluted, the data of each cleaning agent when the data of solution A is 1.000 are obtained. F2 = (washing capacity / elution amount) was calculated and shown in Table 4.
From these results, it is possible to reduce the amount of titanium elution with any of the cleaning agents below B as compared with the conventional cleaning solution, while maintaining a high cleaning ability. It was found that it can be expected as a cleaning agent that suppresses remarkable hydrogen embrittlement.
In particular, the cleaning agent B was highly satisfactory in comprehensive evaluation.

“Test 3”
As a material for directly judging the degree of hydrogen embrittlement, a tensile stress test was performed on the titanium material after cleaning, which is the object to be cleaned.
As shown in Table 5, the test is performed by performing a tensile test of a titanium plate with a cleaning agent according to JISZ2241 “Metal material tensile test method”. After immersion in solution A, tensile stress before and after immersion in solution B The test results are shown in Table 6.
From the results shown in Table 6, the titanium plate immersed in solution B has a tensile strength of about 2 N / mm ² higher and a elongation at break of about 1.2% compared to solution A. It was recognized that it was able to suppress more.

Test 1 shows that the hydrogen embrittlement caused by the detergent is caused by occlusion of hydrogen generated in the dissolution of the metal by the acid inside the titanium. Therefore, it can be seen that the amount of dissolved metal has a significant correlation with the promotion of hydrogen embrittlement. However, increasing the amount of titanium dissolved also increases the cleaning action. Therefore, Test 2 was conducted to evaluate the cleaning ability of calcium compounds and proteins adhering to barnacles and toilet piping attached to the water supply and distribution pipes in the sea.
Next, the characterization of the surface of the titanium plate with detergent is described. The SEM photograph before immersion is shown in FIG. 1, the SEM photograph of the Ti surface after immersion in solution A is shown in FIG. 2, and the SEM photograph after immersion in solution B is shown in FIG.
A difference was observed in the surface state of both the solution A and the solution B before and after immersion, but a slight difference due to dissolution was also observed on the surface of the titanium plate between the solution A and the solution B after immersion.

Fig. 4 shows a metal fracture photograph of test 3, Fig. 4 shows a photo before immersion, Fig. 5 shows a photo after immersion in solution A at 80 ° C for 24 hours, and Fig. 6 shows a photo after immersion in solution B at 80 ° C for 24 hours. Show.
It can be seen that all specimens were deformed and fractured at the center due to tensile stress. Test 3. From the data obtained in, the elongation at break of both the solution A and the solution B after immersion was suppressed from before the immersion, but the difference was as small as about 2 to 3% and could not be confirmed visually.

The measurement result of the hydrogen content in the titanium plate by SIMS (secondary ion mass spectrometry) is shown below. The result before immersion is shown in FIG. 7, the result of immersion in solution A at 80 ° C. for 24 hours is shown in FIG. 8, and the result of immersion in solution B at 80 ° C. for 24 hours is shown in FIG. Further, FIG. 10 is a diagram in which the results of FIGS. 7 to 9 are overlapped. SIMS was measured under the conditions shown in Table 7.
The titanium plate before immersion in FIG. 7 does not contain any hydrogen. In particular, commercially available titanium plates are the result of strict control over hydrogen embrittlement. However, it was found that hydrogen embrittlement of about 40 μm occurred after the immersion of the cleaning liquid A, whereas it was suppressed to about 1/5 of 8 μm after the immersion of the cleaning liquid B. In addition, it has also been found that the concentration of hydrogen contained in the cleaning liquid B decreases to 1/6 or less compared to the cleaning liquid A.

  INDUSTRIAL APPLICABILITY The present invention can be used as a cleaning agent and its aqueous solution for space engineering, aircraft, ships, household excrement facilities, water and sewage facilities, and various other metal products.

The surface photograph of the titanium material before immersion. Solution A A surface photograph of the titanium material after immersion at 80 ° C. for 24 hours. The photograph of the surface of the titanium material after immersion for 24 hours at Solution B 80 ° C. Tension break photo of titanium material before immersion. Solution A: Tension fracture photograph of titanium material after immersion at 80 ° C. for 24 hours. Solution B: Tension fracture photograph of titanium material after immersion at 80 ° C. for 24 hours. The graph which shows the measurement result of the hydrogen content in the titanium plate before immersion by SIMS. The graph which shows the measurement result of the hydrogen content in the titanium plate after being immersed in A solution by SIMS. The graph which shows the measurement result of the hydrogen content in the titanium plate after being immersed in B solution by SIMS. The graph which shows the measurement result of the hydrogen content in the titanium plate in three tests by SIMS.

Claims (6)

  It consists of a mixed solution of sulfamic acid, citric acid, malic acid and alkaline carbonate, and the blending ratio (weight ratio) of sulfamic acid: citric acid: malic acid and alkaline carbonate is 79 to 91: 7 to 3: 7 to 3: The cleaning agent for metal products characterized by being 7-3.   It consists of a mixed solution of sulfamic acid, citric acid, malic acid and alkaline carbonate, and the mixing ratio (weight ratio) of sulfamic acid: citric acid: malic acid and alkaline carbonate is 85: 5: 5: 5 A cleaning agent for metal products.   The cleaning agent for metal products according to claim 1 or 2, wherein the alkaline carbonate is one or a combination of sodium carbonate, sodium hydrogen carbonate, ammonium carbonate, and potassium carbonate.   The metal product cleaning agent according to claim 3, wherein the alkaline carbonate is sodium carbonate.   An aqueous cleaning solution for metal products obtained by diluting the cleaning product for metal products according to claim 1 in water.   An aqueous cleaning solution for metal products obtained by diluting the cleaning product for metal products according to claims 1 to 4 as a 10% aqueous solution in water.