De-icing agent

Abstract

Provided is a snow melting agent which contains at least one selected from the group consisting of sodium chloride, magnesium chloride, and calcium chloride as a major component, and an additive that causes generation of a sulfate ion and a sodium ion.

Description

Technical Field

[0001] The present disclosure relates to deicing agents.

Background Art

[0002] Since zinc corrodes at a slower rate than iron, it is widely used for the anticorrosion of infrastructure steel structures such as streetlights, signal poles, telegraph poles, utility poles, guardrails, etc., in the form of zinc plating, zinc alloy plating, etc. Zinc has an excellent function of forming a protective rust (protective film) when it corrodes, and then suppressing subsequent corrosion (Non-Patent Document 1).

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The corrosion rate of zinc plating is about 0.5 to 1 μm / year in atmospheric corrosion in a mild environment, but it may become extremely high when deicing agents are sprayed in a snowfall area.

[0005] By forming a better-quality protective film of zinc and reducing the corrosion rate, the infrastructure can be made to have a longer lifespan. To reduce the corrosion rate of zinc, techniques for making alloys with other metals such as aluminum and magnesium are also widespread, but alloys are more costly than zinc alone.

[0006] This disclosure is made in view of the above circumstances and aims to provide a snow melting agent that can reduce the corrosion of materials mainly composed of zinc. [Means for solving the problem]

[0007] A snowmelt agent according to one aspect of the present disclosure comprises, as a main component, at least one selected from the group consisting of sodium chloride, magnesium chloride, and calcium chloride, and an additive that generates sulfate ions and sodium ions. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide a snow melting agent that can reduce the corrosion of materials mainly composed of zinc. [Modes for carrying out the invention]

[0009] The snowmelt agent according to the embodiments of this disclosure will be described below.

[0010] The snowmelt agent of this embodiment comprises, as a main component, at least one selected from the group consisting of sodium chloride, magnesium chloride, and calcium chloride, and an additive that generates sulfate ions and sodium ions. Specifically, the snowmelt agent of this embodiment is a mixed powder in which a powder such as sodium chloride is the main component, and a small amount of powder of an additive that generates sulfate ions and sodium ions is added thereto. The snowmelt agent may also further contain a basic salt.

[0011] The main components, additives, and basic salts of the snowmelt agent of this embodiment are described below.

[0012] <Main ingredients> The snowmelt agent of this embodiment contains at least one selected from the group consisting of sodium chloride, magnesium chloride, and calcium chloride as its main component. Specifically, the snowmelt agent may have sodium chloride, magnesium chloride, or calcium chloride as its main component, or it may have a mixture of two or more of sodium chloride, magnesium chloride, and calcium chloride as its main component.

[0013] In the experimental examples described later, common calcium chloride was used as the main component.

[0014] <Additives> The snowmelt agent of this embodiment includes an additive that generates sulfate ions and sodium ions.

[0015] In this embodiment, an additive is used to intentionally precipitate a large amount of gordaite (NaZn4(SO4)(OH)6Cl·6H2O), which has particularly high protective properties among various zinc corrosion products. Gordaite is a substance produced when zinc corrodes, and it has high corrosion resistance, providing an effect of suppressing the progression of subsequent corrosion.

[0016] Since the main components of de-icing agents are often sodium chloride, calcium chloride, or magnesium chloride, chloride ions are supplied from these. Therefore, by supplying sulfate ions, sodium ions, and hydroxide ions, gordaite can be precipitated using zinc ions that dissolve when zinc corrodes. Hydroxide ions can be supplied from, for example, water.

[0017] Therefore, the snowmelt agent of this embodiment includes an additive that generates sulfate ions and sodium ions. Any substance that generates (supplies) sulfate ions and sodium ions may be used as the additive. A sulfate can be used as the substance that generates sulfate ions, and a sodium salt can be used as the substance that generates sodium ions.

[0018] Since sodium sulfate combines both sulfate and sodium salts, it is preferable to use sodium sulfate as an additive.

[0019] Also, when sulfate ions and sodium ions are in separate salts, the proportion of the main component substance of the snow melting agent decreases and the snow melting function deteriorates. Therefore, sodium sulfate, which combines both sulfate ions and sodium ions in one salt, is suitable. In the experimental examples described later, sodium sulfate was used as the additive.

[0020] Considering only the precipitation of a large amount of gordaite, it is desirable to add sodium sulfate in the same amount as the main component substance in terms of molar ratio. However, if a large amount of sodium sulfate is added, the proportion of the main component, which is the snow melting component, decreases and the snow melting function deteriorates.

[0021] Therefore, it is preferable that the main component is more than 70% by weight and the other components are 30% by weight or less. For example, the content of the additive that generates sulfate ions and sodium ions is preferably 30% by weight or less based on the total weight of the snow melting agent. Also, when emphasizing the snow melting function, it is more preferable that the main component is more than 80% by weight and the other components are 20% by weight or less. For example, it is more preferable that the content of the additive is 20% by weight or less based on the total weight of the snow melting agent. In addition, the content of the additive is preferably 0.5% by weight or more.

[0022] General snow melting agents consist only of main components such as magnesium chloride and calcium chloride, but the snow melting agent of this embodiment contains an additive that generates sulfate ions and sodium ions. As a result, when the snow melting agent of this embodiment is used, a high-quality protective film with a large amount of gordaite is formed on zinc (a material with zinc as the main component), and corrosion can be reduced compared to general snow melting agents that do not use an additive.

[0023] <Basic salt> The snow melting agent may further contain a basic salt. The aqueous solution of the basic salt shows alkalinity. For the basic salt, for example, carbonates, metal hydroxides, metal oxides, etc. can be used.

[0024] Zinc is an amphoteric metal, and corrosion progresses even in a high pH region. Therefore, for the basic salt, magnesium basic carbonate with low solubility in water and a pH that does not become too high even in a saturated solution is suitable. However, a small amount of other basic salts may be used so that the pH does not become too high.

[0025] The basic salt only needs to make the aqueous solution weakly alkaline, so much is not necessary. The content of the basic salt is preferably 6% by weight or less, more preferably 3% by weight or less, based on the total weight. Note that the content of the basic salt is preferably 0.2% by weight or more.

[0026] In the experimental examples described later, magnesium basic carbonate was used as the basic salt.

[0027] <Experimental Example 1> Next, the experimental examples of this embodiment will be described. Samples of a plurality of snow melting agents were prepared at the ratios shown in Table 1.

[0028]

Table 1

[0029] Table 1 shows the composition ratios of a plurality of snow melting agents. In Experimental Example 1, calcium chloride was used as the main component (snow melting component), sodium sulfate was used as the additive, and magnesium basic carbonate was used as the basic salt.

[0030] Snow melting agents A and B in Table 1 are the snow melting agents of this example. Snow melting agent A uses sodium sulfate and magnesium basic carbonate in addition to the main component, and snow melting agent B uses only sodium sulfate in addition to the main component. Snow melting agent C is a reference example and uses only magnesium basic carbonate in addition to the main component. Snow melting agent D is a comparative example and is a snow melting agent with only the main component.

[0031] Each snow melting agent and tap water were mixed at a weight ratio of 10:90 to prepare an aqueous solution. Then, each aqueous solution was sprayed at 30 g / m using a wet spraying type snow melting agent spraying vehicle ,

[0030] , , , , , ,

[0029] , 2 ,

[0031] [The required amount was applied to each surface. A 70mm x 150mm x 1mm pure zinc plate with the back side sealed was used for each surface, and the pure zinc plate was installed after measuring its initial weight.

[0032] After being left for one week following application, each pure zinc plate (applied surface) was collected, and the corrosion rate of each de-icing agent was calculated by comparing its weight after rust removal with its initial weight. Here, the corrosion rate was normalized to the corrosion rate of the comparative example de-icing agent D, which was set to 100.

[0033] Table 2 shows the experimental results, specifically the corrosion rate (after normalization) after application of each de-icing agent.

[0034] [Table 2]

[0035] De-icing agent A, which contained both sodium sulfate and basic magnesium carbonate, showed the greatest reduction in the corrosion rate of zinc. De-icing agent B, which contained only sodium sulfate, and de-icing agent C, which contained only basic magnesium carbonate, also showed a reduction in corrosion rate compared to de-icing agent D (comparative example), which contained neither sodium sulfate nor basic magnesium carbonate.

[0036] Furthermore, no decrease in snow-melting performance was observed between snow-melting agents A-C and snow-melting agent D, which is 100% calcium chloride.

[0037] Thus, it was found that effectiveness could be obtained using either sodium sulfate or basic magnesium carbonate, and even better results could be obtained when both were used. Specifically, when sodium sulfate (sulfate) and basic magnesium carbonate (basic salt) were added, more Gordaite was precipitated, and the reduction of the precipitated Gordaite by weakly acidic rainwater could be mitigated.

[0038] Sodium sulfate supplies the sodium and sulfate ions necessary for the precipitation of gordaite. Basic magnesium carbonate supplies the hydroxide ions necessary for the precipitation of gordaite and also makes the pH of the aqueous solution weakly alkaline. As a result, the de-icing agent of this embodiment can be controlled to conditions under which zinc, an amphoteric metal, is less likely to corrode.

[0039] Furthermore, as can be seen from the chemical formula of gordaite (NaZn4(SO4)(OH)6Cl·6H2O), any sulfate that can supply sulfate ions other than sodium sulfate can be suitably used as an additive. Any sodium salt that can supply sodium ions other than sodium sulfate can be suitably used as an additive.

[0040] In addition to basic magnesium carbonate, any basic salt that can supply hydroxide ions and make the aqueous solution alkaline (e.g., carbonates, metal oxides, metal hydroxides) can be suitably used. However, when using basic salts other than basic magnesium carbonate, it is necessary to calculate the amount to add to the aqueous solution so that the pH does not become too high.

[0041] Specifically, it is necessary to add a basic salt so that the pH of the aqueous solution does not exceed pH 12. In the case of basic magnesium carbonate, its solubility in water at room temperature is 0.25 g / L, so a saturated solution can be used as is, and there is no problem even if an excess amount of basic magnesium carbonate is added. For this reason, using basic magnesium carbonate simplifies the operation. This is a major advantage that other basic salts do not have.

[0042] Furthermore, since industrial or agricultural grades of sodium sulfate and basic magnesium carbonate can be used instead of reagent grade, there is the advantage of very low procurement costs.

[0043] In Experimental Example 1, tap water was used, but pure water, or water containing trace amounts of impurities such as rainwater, well water, river water, industrial water, or agricultural water may also be used.

[0044] As described above, the snow-melting agent of this embodiment allows for snow-melting work to be carried out at low cost while reducing corrosion (damage) to outdoor infrastructure using materials mainly composed of zinc. Specifically, even if materials mainly composed of zinc corrode due to the snow-melting agent of this embodiment, a high-quality protective film is formed, thereby reducing corrosion compared to general snow-melting agents and extending the lifespan of infrastructure equipment.

[0045] This disclosure is not limited to the embodiments described above, and various modifications and combinations are possible within the technical concept of this disclosure.

Claims

1. The main component is at least one selected from the group consisting of sodium chloride, magnesium chloride, and calcium chloride, It includes an additive that generates sulfate ions and sodium ions. The aforementioned additive is sodium sulfate. Snow melting agent.

2. The snowmelt agent according to claim 1, further comprising a basic salt.

3. The basic salt is basic magnesium carbonate. The snowmelt agent according to claim 2.

4. The content of the aforementioned additive is 30% by weight or less relative to the total weight. The snowmelt agent according to claim 1 or 2.

5. The content of the basic salt is 3% by weight or less relative to the total weight. The snowmelt agent according to claim 2.

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