JP2003041193A - Rust-preventive agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waterborn rust-preventive agent that controls the occurrence of rust for a long time of period even in rainy days and is used for the reinforcing wires exposed on the cut plane surface of light-weight hollow concrete. SOLUTION: The waterborn synthetic resin rust-preventive agent includes at least one selected from the salts of alkali metal or alkaline earth metal in an amount of 1-20 wt.% as a reducing agent in the rust-preventive agent. In the rust-preventive agent, the water-born synthetic resin is selected at least one or more from alkyd resin, phthalic acid resin, phenol resin, epoxy resin, acrylic resin and chlorinated rubber resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rust preventive agent applied to a reinforcing bar exposed on a cut surface of a lightweight cellular concrete panel for rust prevention.

[0002]

2. Description of the Related Art Lightweight cellular concrete panels (hereinafter referred to as A
It is called LC. ) Is lighter than concrete,
Due to its advantages such as fire resistance, heat insulation and workability, it has been widely used as a building material for outer walls, partitions, floors, roofs, etc.

Further, the ALC has a reinforcing bar built therein to secure the panel strength. The reinforcing bar does not have rust due to the neutralization after the manufacture, so that a cement system or a cement system is used at the manufacturing stage of the ALC. Asphalt-based and water-based synthetic resin-based rust preventives are applied, and finally cured by high temperature and high pressure steam.

[0004] However, because of its easy workability, ALC is frequently performed in joints and various sites of a building, and jointing and cutting and drilling for size adjustment are frequently performed at ALC manufacturing factories and building sites. ing. For the rustproofing treatment at the construction site, since the surrounding area is open type, commercially available organic solvent-based rustproofing paint with fast drying is often used.
In the case of application in the C manufacturing plant, the use of the above-mentioned quick-drying organic solvent-based anticorrosive paint is very limited because the building is either closed type or partially open type. The current situation.

[0005]

When applying the above-mentioned quick-drying rust preventive paint, it is necessary to carry it outside the building every time and apply the organic solvent-based rust preventive paint, which is very troublesome. It was Further, when a water-based rust preventive paint is used instead of the organic solvent-based rust preventive paint, there is a problem that rust is generated quickly because the curing speed is slow.

Further, when the above water-based anticorrosive paint is applied when the water content is high such as immediately after steam curing or in the rain,
There is also a problem that rust occurs before the paint is dried. Therefore, an object of the present invention is to provide a water-soluble rust preventive agent which suppresses the generation of rust for a long time even in rainy weather and can be used indoors.

[0007]

The rust preventive agent according to the present invention is a rust preventive agent to be applied to a reinforcing bar exposed on a cut surface of a lightweight cellular concrete panel. First, it is an aqueous synthetic resin rust preventive agent. The rust preventive agent is a rust preventive agent containing at least one of salts of alkali metals or alkaline earth metals as a reducing agent.

Secondly, the aqueous synthetic resin is at least one resin selected from alkyd resins, phthalic acid resins, phenolic resins, epoxy resins, acrylic resins and chlorinated rubber resins. It is a rust preventive agent.

Thirdly, the content of the reducing agent in the first or second invention is 1 to 20% by weight based on the aqueous synthetic resin-based rust preventive. It is a rust preventive agent.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The embodiments of the present invention will be described below. When the reinforcing bar portion inside the ALC is cut, a section of the cut reinforcing bar appears. A rust preventive agent is applied to the cross section of the reinforcing bar to prevent the generation of rust. Conventionally, an organic solvent-based rust preventive agent containing a resin or a pigment and having good rust preventive performance is generally applied.

The organic solvent-based rust preventive agent is a rust preventive paint in which an organic solvent such as xylene, thinner or toluene is used, but recently, an aqueous rust preventive agent which is harmless to the human body is being used. The rust preventive used in the present invention is an aqueous synthetic resin-based rust preventive, and the term "water-based" means one using water as a solvent or one dilutable with water. Therefore, since no organic solvent is used, there is no fear of pollution such as pollution or fire, and cleaning of paint equipment such as brushes, rollers and spray guns, and cleaning up with paint can be done easily with water.

The rust preventive agent used in the present invention uses harmless water as the dispersion medium of the coating material, and in order to improve the coating performance, it is a water-based alkyd resin, enamel resin, epoxy resin, acrylic resin. It contains at least one of a resin and a chlorinated rubber resin, and further contains a salt of an alkali metal or an alkaline earth metal as a reducing agent. Examples of the alkali metal include salts of Li, Na, K and the like, specifically KNO ₂ , K ₂ SO ₃ , LiNO ₂ , NaNO ₂ ,
Such as Na ₂ SO ₃ and the like. The alkaline earth metal is a salt of Ca, Ba, Mg or the like, specifically Ca (N
_{O 2) 2, Ba (NO} 2) 2, Mg (NO 2) 2 and the like.

The metal salt used as the reducing agent is highly soluble in water and has a greater electropositive property than other substances, so that rust due to oxidation can be prevented. Therefore, the above-mentioned salt having a solubility in water of 20% or more is economically preferable. Further, by setting the content of the reducing agent to 1 to 20% by weight with respect to the aqueous synthetic resin-based rust preventive, the rust preventive effect is exhibited. If it is less than 1% by weight, the rust preventive effect is low, and if it is more than 20% by weight, the effect is not changed, which is economically wasteful. From the viewpoint of performance and economy, 3 to 15% by weight is more effective.

Furthermore, since the color of the rust preventive applied and dried is close to the same color as the appearance of the ALC, specifically, the aqueous synthetic resin rust preventive so that the color difference ΔE with the ALC is 5 or less. It is desirable to add 10% by weight or less of the pigment. When the color difference ΔE is 3 or less, it is difficult to identify the color difference and the appearance is further improved.

[0015]

EXAMPLES Examples of the present invention will be described in detail below. Silica powder as siliceous raw material, ordinary Portland cement and quicklime powder as calcareous raw material, and further water,
A predetermined amount of aluminum powder, ALC cutting powder, and the like were mixed, and the mixture was placed on a mold in which a reinforced anticorrosive reinforcing bar cage was placed. Next, after foaming / curing, the product was cut into a desired size, and then subjected to high temperature / high pressure steam curing to complete a white ALC 10 having reinforcing bars inside (FIG. 1).

Then, the ALC10 produced by the above method
Was cut along the width direction at the center in the length direction with a cemented carbide cutter and subjected to a test for evaluation of rust prevention performance. The cut surface of the reinforcing bar 11 is seen in the cut cross section together with the ALC base material (FIG. 2). A rust preventive agent is prepared by adding 1 to 10% by weight of titanium oxide as a coloring paint to an alkyd-based water-based resin-based paint and further mixing 1 to 20% by weight of sodium nitrite as a reducing agent on the cross section of the reinforcing bar 11. The cross section was applied with a spray gun.

In order to evaluate the rust preventive performance of Examples embodying the present invention, after applying the above-mentioned rust preventive agent, water was sprayed on the applied site and the presence or absence of rust was observed. When rust was generated, the rust prevention performance was evaluated by measuring the generation time and the generation area. At the time of watering, water was sprayed indoors on the rebar portion of the ALC cut surface, and again 1 hour after the first watering at the watering site. After that, watering was repeated twice daily for 14 days, and the presence or absence of rust was visually observed. The results are shown in Table 1. Further, the color difference ΔE of the rust preventive after drying was also measured. The results are also shown in Table 1.

[0018]

Comparative Example The ALC 10 used in the example was cut in the same manner as above, and a rust preventive agent was applied to the cross section of the reinforcing bar 11. The rust preventive agent at that time was prepared by changing the compounding amount of the reducing agent and by changing the adding amount of the coloring paint, and applied to the cross section of the reinforcing bar. After that, water sprinkling was performed under the same conditions as above, and the rust generation state and the like were observed. The results are shown in Table 1 as above.

[0019]

[Table 1]

As is clear from Table 1, when a rust preventive containing no reducing agent is applied, rust is observed in 50% of the area by 3 days. Further, after 7 days, the generation of rust becomes 100% in all. In addition, rust occurred in a short period even when the amount of the reducing agent was small. In contrast, when a rust preventive agent containing at least one of alkali metal salts and alkaline earth metal salts was applied as the reducing agent in this example, no rust was observed even after 14 days. It was found to have sufficient rust prevention ability.

Further, the color difference ΔE with the ALC base material did not exceed 2.0 under any mixing condition, and the color difference with the ALC base material was hardly recognized by visual observation, and the appearance was good. .

[0022]

INDUSTRIAL APPLICABILITY As described above, the product of the present invention is used as a water-based synthetic resin-based rust preventive for preventing rust from reinforcing reinforcing bars exposed in a cross section of a cut ALC. By using a rust preventive agent containing 20% by weight of at least one salt of an alkali metal or an alkaline earth metal, it has a sufficient rust preventive ability for a long period of time.

[Brief description of drawings]

FIG. 1 is an ALC perspective view.

FIG. 2 is a perspective explanatory view showing a cross section of the ALC.

[Explanation of symbols] 10 ALC 11 Reinforcing bar cutting section

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Claims (2)

[Claims] 1. A water-based synthetic resin-based rust preventive applied to a reinforcing bar exposed on a cut surface of a lightweight cellular concrete panel, wherein the rust preventive is a reducing agent selected from alkali metal or alkaline earth metal salts. A rust preventive agent containing at least one of the above components, and further containing 1 to 20% by weight of the content of the components with respect to the aqueous synthetic resin rust preventive agent. 2. The aqueous synthetic resin in the rust preventive agent is at least one resin selected from alkyd resins, phthalic acid resins, phenolic resins, epoxy resins, acrylic resins and chlorinated rubber resins. The rust preventive agent according to claim 1, which is present.