KR100505321B1 - Composition for removing scale deposited on titanium materials - Google Patents

Abstract

A descaling agent used to remove scale attached to a member made of titanium or titanium alloy, containing oxycarboxylic acid, sulfonic acid and ammonium sulfate as an active ingredient, and having excellent solvent resistance to titanium ions.

Description

Scale remover attached to titanium material {COMPOSITION FOR REMOVING SCALE DEPOSITED ON TITANIUM MATERIALS}

The present invention relates to a scale remover, and more particularly, to a scale remover adhered and deposited on an inner wall of a titanium drain pipe.

For example, calcium compounds produced by decomposition of water-insoluble organic matter and urine, which are decomposed into food debris, are attached to the inner wall of kitchen or toilet drain pipe. This attachment is commonly referred to as scale and worsens the drainage flow. In pipes with small pipe diameters and many bends, scale build-up causes blockage of the drain pipe.

In the aircraft, the cooking chamber and toilet drain pipe are restricted in gas structure, so the tubular structure is complicatedly inserted into a narrow space. In order to avoid the blockage of the drain pipe, descaling is frequently performed. However, if strong acid inorganic acids such as hydrochloric acid and sulfuric acid, which have high scale removal effect, are used, the drain pipe not only causes material deterioration due to corrosion but also wastewater after cleaning. On the other hand, if a weak acid such as acetic acid is not enough to obtain a descaling effect, it is necessary to periodically remove the drain pipe to physically remove the scale in the pipe. This work is filthy, difficult and takes a long time, which interferes with the flight schedule.

The inventors have previously developed a scale remover which can effectively dissolve and remove scale without using a strongly acidic inorganic acid (Japanese Patent Laid-Open No. 2000-63890). This is a composition containing oxycarboxylic acid and sulfonic acid as an active ingredient, which is not only corrosive to the tube material but also has excellent biodegradability, so there is no fear of causing environmental pollution. This descaling agent was originally developed as a denture cleaner for dissolving and removing dentures or tartar of dentures.However, since the dung and tartar components are almost the same as the drain pipe scale, they are used as descaling agents for cooking chambers and toilet drain pipes in aircrafts. Outstanding effect was found.

However, in the aircraft cooking compartment or toilet drain pipe, since lightness is important in addition to corrosiveness, a titanium alloy containing titanium or titanium and other metal elements (hereinafter simply referred to as "titanium material") is preferably used as the pipe material. Titanium material is formed at the instant of a film of titanium oxide having high adhesion to the surface of the titanium material under an air atmosphere, and since the film protects the base material, corrosion resistance is extremely good. However, since the film of titanium oxide is considerably thin, the film is easily removed when contacted with a chemical containing a strong acid. Descaling with a strong acid descaling agent first removes the scale and then the oxide film underneath. If the descaling agent is added as it is, the surface of the titanium material is corroded by the descaling agent and titanium ions are eluted. When the descaling agent is stopped at the same time as the descaling is completed, the elution of the titanium ions can be suppressed, but in practice, it is difficult to control the work with such a high timing. For this reason, the elution of titanium ions cannot be avoided in the scale removal operation attached to the drain pipe made of titanium material.

An object of the present invention is to provide a scale remover which is excellent in scale dissolving action and excellent in solvent resistance of titanium ions (with little elution of titanium ions) in a scale remover attached to a drain pipe made of titanium material.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining the outline of the scale removal test attached to the inner wall of the drain pipe removed from an aircraft.

In order to achieve the above object, the scale remover of the present invention is a composition containing ammonium sulfate as an active ingredient in addition to oxycarboxylic acid and slpermic acid.

It is preferable that ammonium sulfate is contained more than 0% and 5 weight% or less with respect to the total weight of oxycarboxylic acid, a sulfonic acid, and ammonium sulfate.

The scale remover of this invention contains an oxycarboxylic acid, a sulfuric acid, and ammonium sulfate as an active ingredient, and is demonstrated in detail below.

The descaling agent of the present invention has high solubility for scales including calcium compounds due to the coexistence of oxycarboxylic acid and slpermic acid, and exhibits an excellent descaling effect.

Oxycarboxylic acid is a generic term for those containing alcoholic hydroxyl group and carboxyl group in its molecular structure, for example, glycolic acid, malic acid, lactic acid, tartaric acid, citric acid, hydroacrylic acid, -oxynalic acid, glycerin acid, tartronic acid and the like. Aromatic oxycarboxylic acids, such as an acid, a salicylic acid, metaoxybenzoic acid, a paraoxybenzoic acid, a molar acid, mandelic acid, and a tropaic acid, are mentioned, but it is not limited to these. Malic acid and citric acid are also preferred. This oxycarboxylic acid can use not only one type but two types or more simultaneously as desired.

Amidosulfonic acid is preferably used as the sulfonic acid, but is not limited thereto. In the case of using amidosulfonic acid, it is preferable to use N-alkyl and N-aryyl derivatives having high water solubility among the derivatives.

The oxycarboxylic acid and the slpermic acid used in the present invention may be safe even if used for a long time, and are preferably solid at room temperature, and more preferably have a structure close to a natural product and excellent in biodegradability.

It is preferable that it is 1: 9-9: 1, and, as for the oxycarboxylic acid to slpermic acid weight ratio, it is more preferable that it is 1: 9-7: 3.

The scale remover of the present invention is characterized in that it comprises ammonium sulfate. The inventors have found that ammonium sulfate has the effect of inhibiting the dissolution of titanium ions on the surface of the titanium material without disturbing the descaling action of the oxycarboxylic acid and the sulfuric acid, the content of which is oxycarboxylic acid, the sulfuric acid and It is preferable that it is 5 weight% or more beyond 0% with respect to the total weight of ammonium sulfate.

When the scale remover of this invention requires immediate effect for scale dissolution, it is preferable to obtain what is a powder or granule form, to mix this uniformly, and to use it as an aqueous solution. The aqueous solution concentration is preferably about 50 g to about 200 g (equivalent to about 5 to about 17 wt% aqueous solution) in total amount of oxycarboxylic acid, sulfonic acid and ammonium sulfate, for example, for 1000 m water of water, and about 100 g to about 140 g (about Equivalent to 9-about 12% by weight aqueous solution) is more preferred.

On the other hand, in order to maintain the descaling effect over a long period of time, it may be formed into a molded article having an appropriate shape by using a binder having a function of delaying the dissolution of oxycarboxylic acid and sulfonic acid into water. Depending on the amount of the binder blended, the reception time can be controlled appropriately.

As binders for example starch, carboxymethylcellulose (CMC), sodium carboxymethylcellulose (CMC-Na), polyvinylpyrrolidone (PVP), hydrooxypropylcellulose (HPC), hydrooxypropyl starch (HPS) ), But is not limited to these.

The molded article is based on a mixed powder containing oxycarboxylic acid powder, sulfonic acid powder, and ammonium sulfate, and the mixture of 5-100 parts by weight of the binder powder is uniformly mixed with respect to 100 parts by weight of the base in a predetermined shape. It can be molded.

Moreover, the scale remover of this invention can mix and use an oxidizing agent, surfactant, an enzyme agent, a chelating agent, etc. as needed.

When the remover of the present invention is used for the scale removal operation attached to the inner wall of the cooking chamber of the aircraft or the toilet drain pipe, the remover is first dissolved in water to prepare an aqueous solution of the remover. When the aqueous solution of the remover is injected from the cooking chamber and the toilet drain, the aqueous solution of the remover passes through the inside of the drain pipe while dissolving the scale attached to the pipe wall and reaches the drain inlet at the bottom of the aircraft. Since the aqueous solution here contains the scale removed from the drain pipe, the scale is separated through a separator and the separated scale is accommodated in a predetermined container. The descaler aqueous solution is returned to the cooking chamber and toilet drain and passed through the drain pipe. The time required to circulate the remover aqueous solution to remove the scale depends on the size of the aircraft and the degree of adhesion of the scale.

Next, specific examples will be described.

Example 1

Test tablets (diameter 5 mm) of various calcium compounds were formed by using a tablet molding machine, and the spheres were immersed in various test solutions for each type of calcium compound to investigate the dissolution state of the calcium compounds.

Calcium compounds provided for the dissolution test are calcium phosphate, calcium carbonate, calcium hydroxide and calcium sulfate.

The test results are shown in Table 1 below.

Sample No. 1 in Table 1 is an example of the invention, in which 500 g of distilled water is dissolved 10 g of L-peracid and 10 g of citric acid as oxycarboxylic acid, and 5 g of amidosulfonic acid and 1 g of ammonium sulfate as slurmic acid.

The test solution No. 2 is a comparative example containing no ammonium sulfate. In 500 ml of distilled water, 10 g of L-peracid and 10 g of citric acid and 5 g of amidosulfonic acid were dissolved as slurmic acid.

Sample No. 3 is a weak acid, for example 500 ml of commercial acetic acid.

Test solution No. 4 is a strongly acidic inorganic acid, for example, 500 l of hydrochloric acid at a 5% concentration.

Table 1

Disclosure Dissolution test result of calcium compound Calcium phosphate Calcium carbonate Calcium hydroxide Calcium sulfate No.1 Dissolves in 30 minutes for 3 hours of micronization Dissolves in 30 minutes for 3 hours of micronization Dissolves in 30 minutes for 3 hours of micronization Dissolves in 30 minutes for 3 hours of micronization No.2 Dissolves in 30 minutes for 3 hours of micronization Dissolves in 30 minutes for 3 hours of micronization Dissolves in 30 minutes for 3 hours of micronization Dissolve micronized three hours in 30 minutes No.3 Almost unchanged Almost unchanged Almost unchanged Almost unchanged No.4 Dissolves in 30 minutes for 3 hours of micronization Dissolves in 30 minutes for 3 hours of micronization Dissolves in 30 minutes for 3 hours of micronization Dissolves in 30 minutes for 3 hours of micronization

Referring to the results of Table 1, the dissolution time of the calcium compounds of the test solutions No. 1 and No. 2 was almost equivalent to that of the hydrochloric acid of No. 4, indicating that they had excellent dissolving power to the calcium compounds. Moreover, the removal effect of calcium compound was hardly recognized by the No. 3 test solution.

As described above, the scale attached to the inner wall of the drain pipe is mainly composed of a calcium compound, and it can be seen that the scale remover of the present invention has an excellent descaling effect because of its high solubility in the calcium compound.

Example 2

The drain pipe connected to the cooking chamber of the airplane was removed and the effect of descaling on the inner wall of the pipe was investigated. The drain pipe was made of pure titanium and had a diameter of 2 inches (about 50 mm), a length of 92.6 inches (about 2350 mm), and a part of the drain pipe was bent smoothly.

An outline of a scale removal test is shown in FIG. Referring to FIG. 1, (1) is a tank, and the scale remover aqueous solution 2 of this invention is contained in it. The aqueous solution 2 contained 800 g of L-peracid and 800 g of citric acid as an oxycarboxylic acid, 400 g of amidosulfonic acid as a sulfonic acid, and 80 g of ammonium sulfate in 20 liters of water.

Denoted at 3 is a drain pipe, and a scale 9 is attached to the inner wall of the drain pipe 3. Tubes 4 and 5 made of translucent polyvinyl chloride are connected to respective ends of the drain pipe 3. The end of one tube 4 is connected to the pump 6, and the other tube 5 is immersed in the aqueous solution 2. The pump 6 used is 1/6 horsepower and the rated flow is 17.5 gpm with a 5 foot head. 7 is a support for supporting the drain pipe 3.

The pump 6 was operated to circulate the descaling agent aqueous solution 2 in the tank 1 through the drain pipe 3. After 3 hours, the pump 6 was stopped, the tubes 4 and 5 were removed, and visual inspection of the inner wall of the drainage pipe showed that the scale was almost completely removed.

Example 3

Test specimens made of pure titanium were immersed in the same test solutions (liquid amount 500 ml, temperature 25) as in Example 1 to investigate the elution of titanium ions. In addition, the elution amount of titanium ion was measured with the atomic absorption photometer.

The test specimens used a cylindrical body having an inner diameter of 50 mm, an outer diameter of 53 mm, and a length of 50 mm.

Table 2 shows the relationship between the immersion time of the test specimens and the amount of titanium ion elution.

TABLE 2

Disclosure Titanium ion elution amount (g / ml) After 24H immersion After 48H immersion After 120H immersion No.1 0.02 0.04 0.08 No.2 0.06 0.09 0.12 No.3 0.04 0.06 0.11 No.4 0.20 0.25 0.30

Referring to the result of Table 2, the test solution No. 1 of the invention example has less titanium ion elution amount than the test solution No. 2 of the comparative example which does not contain ammonium sulfate. This shows that ammonium sulfate has an effect of inhibiting the dissolution of titanium ions.

Acetic acid in test solution No. 3 has a slight dissolution amount of titanium ions when compared to test solution No. 2, but has little dissolution effect of calcium compounds as shown in Example 1 and is inadequate as a scale remover.

Hydrochloric acid in test solution No. 4 has a large amount of titanium ion elution and causes deterioration of the titanium material.

From the results of Examples 1 to 3, it can be seen that the descaling agent of the present invention is excellent in dissolving action of the calcium compound constituting the scale and at the same time inhibiting elution of titanium ions.

Therefore, even when the scale remover is in contact with the surface of the titanium material after the scale is removed when the scale is attached to the inner wall of the drain pipe made of titanium material, the leaching of titanium ions from the titanium material is suppressed. Material degradation of the pipe is prevented.

Since the descaling agent of the present invention is excellent in solvent resistance of titanium ions, it is useful for removing a member made of a titanium material, for example, a scale attached to an inner wall of a drain pipe of a cooking chamber or a toilet in an aircraft. As other members made of titanium, there are various pipes in heat exchangers, nuclear power equipments, and the like. The scale remover of the present invention is also useful for removing scales attached to the pipe walls of these pipes.

Claims (6)

delete It is water-soluble and used to remove scale attached to the member made of titanium or titanium alloy, and contains oxycarboxylic acid, slurmic acid and ammonium sulfate as active ingredients, wherein the ammonium sulfate is composed of oxycarboxylic acid, slurmic acid and ammonium sulfate. A scale remover containing more than 5% by weight and not more than 0% of the total weight and having excellent solvent resistance of titanium ions. The scale remover of claim 2 wherein the weight ratio of oxycarboxylic acid to slurmic acid is from 1: 9 to 9: 1. The oxycarboxylic acid of claim 2 is glycolic acid, malic acid, lactic acid, tartaric acid, citric acid, hydroacrylic acid, -oxylactic acid, glycerin acid, tartronic acid, salicylic acid, metaoxybenzoic acid, paraoxybenzoic acid, molar acid, mandelic acid and tropamic acid. At least one or more acids selected from the group consisting of descalers. The scale remover according to claim 2, wherein the slurminic acid is amidosulfonic acid. A method of removing a scale made of titanium or a titanium alloy and attached to an inner wall of a drain pipe connected to a cooking chamber or a toilet in an aircraft, the oxycarboxylic acid, sulfonic acid, and ammonium sulfate as an active ingredient, and the oxy The weight ratio of carboxylic acid to sulfonic acid is from 1: 9 to 9: 1, and the ammonium sulphate drains an aqueous solution containing not less than 0% and not more than 5% by weight relative to the total weight of oxycarboxylic acid, sulfamine and ammonium sulfate. And removing the scale attached to the member while suppressing the elution of titanium ions from the drain pipe.