JPH1068233A - Recovering method for contaminated stone and stone contaminant removing agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and effectively remove the yellowing generated on a stone from the inside and a contaminant generated when rust is deposited from the outside without damaging the stone face by applying a reducing agent to the surface of the stone, and removing the contaminant generated on the surface of the stone. SOLUTION: A stone having a contaminant is heated and dried by far infrared rays, and a reducing agent such as ammonium thioglycolate having the concentration of about 20-80% is applied to the surface of the stone to remove the contaminant generated on the surface of the stone. When the contamination is a considerable level, an ammonium thioglycolate solution is kneaded with a holding material such as grain powder into a paste shape, it is applied to the surface of the stone at the thickness of several mm, the coated position is covered with a resin sheet or a film, and the paste is kept in contact with the surface of the stone for some time. When a light pink color is stuck to the stone after this reducing process, an oxidant such as an oxygen bleaching agent is preferably applied to the surface of the stone after the reducing process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for repairing stones, concrete walls and the like in which contamination such as yellowing has occurred, and to a stain remover therefor.

[0002]

2. Description of the Related Art A plate-like stone made of marble, granite or the like is widely used as an interior / exterior material and a floor material of a building. These plate-like stone materials are fixed to the surface of a wall or a floor by a method called a wet method or a dry method. The wet method is a method mainly used for fixing floor materials, and stone materials are fixed on a base surface with mortar. The dry method is a method mainly used for fixing a wall material, and a stone material is fixed with a metal fitting and a screw or an adhesive slightly away from a base surface.

[Problems to be solved by the invention]

[0003] In a stone material fixed by a wet method, a phenomenon that the surface of the stone material turns yellow with time is often observed. This phenomenon is particularly noticeable in white marble such as Bianco Carrara, but also occurs in other light-colored stones such as granite. Even in the dry method, when a stone is pasted on a wall with a two-part adhesive using a curing agent, if the adhesive and the curing agent are not sufficiently mixed, the adhesive oozes out on the stone surface and becomes contaminated. Occurs. Further, in an environment where rainwater, drainage, etc., flow around the back surface, discoloration occurs as in the case of the wet method.

[0004] Originally, the use of stone such as marble as a surface material of a building is to make use of its luxury, and such contamination of the surface of the stone greatly impairs the aesthetics of the building at an angle. The meaning of using stone is lost.
However, at present, no method has been found to restore such contaminated stone. For this reason, at present, such contaminated stone materials are left as they are in buildings and the like.

[0005] Since yellowing is observed only in the case of the wet construction method and the case of the dry construction method using an adhesive, the mortar component or the adhesive component under the stone penetrates the inside of the stone and leaches to the surface. It is thought that it was done. On the other hand, besides such contamination due to internal leaching, rust contamination contained in water dripping from an iron fence, a copper roof, or the like, for example, is often seen in the case of an outdoor structure. In the case of such external contamination, not only stone materials but also concrete walls are a problem. In the case of concrete walls, when the appearance does not need to be taken into account much like a dam, sand blasting, sanding, etc. are used to grind the surface to remove contamination. It causes problems such as deterioration of the environment and pollution of the surrounding environment. In the case of a building in an urban area, in addition to such deterioration of the environment, damage to the appearance is often a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve these problems, and a first object of the present invention is to prevent stones from contaminating due to yellowing from inside and adhesion of rust from the outside. It is an object of the present invention to provide a method for easily and effectively removing a surface without damaging the surface.

[0007] A second object of the present invention is to apply such decontamination to the surface of a concrete structure so as to eliminate the above-mentioned various problems caused by the conventional grinding operation. It is to provide a method.

[0008]

The method for repairing contaminated stone materials according to the present invention, which has been made to solve the above problems, comprises:
By applying a reducing agent to the surface of the stone, contamination generated on the surface of the stone is removed.

As described above, since yellowing of stones occurs only in the case of the wet method or in the case of fixing with an adhesive, it is considered to be due to the leaching of some components from the mortar or adhesive of the foundation, but the details are still unknown. is there. However, the research by the present inventors has revealed the following.

When the surface of the mortar-fixed marble Bianco Carrara, in which yellowing is noticeable, is analyzed by an EPMA (electron beam microanalyzer), Ca (calcium) is found in the non-yellowing portion of the ground tissue (white tissue). only,
The peaks of Ca and Mg (magnesium) appear largely at the black streak portions where the yellowing has not occurred, whereas Ca, Si (silicon), Al (aluminum), P (phosphorus), A K (potassium) peak is detected. From this, in the case of Bianco Carrara, water containing these components leached from the underlying mortar, and when they reached the surface of the stone, these components combined with oxygen in the air, causing yellowing I guessed it.

Therefore, the present inventors conducted a test on the assumption that yellowing could be removed by reducing the surface of the stone material. However, it has been found that when a strong reducing agent is applied, the yellowing is quickly faded, but the stone surface is eroded and loses its luster, significantly impairing its appearance. Therefore, as a result of repeated investigations to perform the reduction treatment gently, it was found that almost neutral ammonium thioglycolate was used as the reducing agent, and that the reducing agent was kept in contact with the surface of the stone for a long time. The present inventors have devised to apply a solution obtained by kneading an ammonium thioglycolate solution with a holding material such as flour to form a paste on the surface of a stone material. As the holding material, various powders such as a powder of a water-absorbing plastic can be used as long as they can hold moisture, in addition to the flour.

Further, it is effective to apply a kneading agent and cover the resin sheet or film, depending on the surrounding conditions, such as easy drying under direct sunlight or weather.

[0013] By treating the surface of the contaminated stone with the weak reducing agent for a long time as described above, the surface of the stone is prevented from being damaged.
In some stones, the yellow color was greatly reduced only by this reduction treatment, and the color was close to the original state. Accordingly, it has been found that yellowing can be repaired depending on the stone material only by applying such a reducing agent.

However, in some cases, the area where the reducing agent is applied may be discolored to pink although it is thin.
In this case, the stone was then oxidized with a weak acid, and most of the stone surface returned to its original color. In the case of the oxidizing agent, similarly to the case of the above-described reducing agent, if a strong acid is used, the surface of the stone is damaged, so that the weak oxidizing agent is held in a holding material such as flour to form a paste, and by applying it, It is desirable to perform a mild oxidation treatment over time.

The method of the present invention is not necessarily effective only for Bianco Carrara, but is also effective for other light-colored stones such as other light-colored marble and granite.

[0016] Also, with respect to contamination due to rust adhesion to the concrete surface, the contamination can be removed by applying a reducing agent in the same manner as described above. In this case, subsequent treatment with an oxidizing agent is unnecessary. The rust attached to the concrete surface can be removed with an acid. However, for example, in the case of treating the surface of a dam, if the acid flows into a river, it causes environmental pollution. On the other hand, the reducing agent used in the present invention, particularly a neutral weak reducing agent such as ammonium thioglycolate, rarely pollutes the environment even if it flows into a river.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, if the contaminated stone contains moisture, it is difficult to make the reducing agent penetrate into the stone. In this case, the stone is heated and dried. The applicant of the present application filed a patent application (Japanese Patent Application No.
No. 6661) proposes a method of drying stones by heating with far infrared rays or mid infrared rays. In the present invention, in order to dry stone as a pretreatment,
The method disclosed in the above application can be suitably applied.

[0018] For example, if the thickness 25~30mm about stone moisture therein is almost saturated with respect to stone area of about 0.5 m ^2, the heat generation amount at a distance of about 10 to 30 cm 0. Place a far-infrared heater of about 3 to 5 kW, and adjust the temperature of
~ 1 hour, far infrared or middle infrared (wavelength 2.5 ~ 1
Irradiation of about 000 μm, preferably about 2.5 to 25 μm) makes it possible to substantially remove the water inside the stone without damaging the stone. However, at the construction site, water often permeates further into the stone from the back side of the stone. The state in which the water inside the stone is removed is ensured (Japanese Patent Application No. 8-186661).

Of course, if the stone is already in a dry state, the above heat treatment can be omitted.

After the heat treatment, a reducing agent is applied to the surface of the stone. In this reduction treatment, if the degree of contamination is light, it is possible to remove the contamination by a method such as applying a liquid reducing agent to the surface of the stone and rubbing it lightly. Examples of the reducing agent include ammonium thioglycolate having a concentration of about 20 to 80%, but other than this, any neutral reducing agent can be used in the same manner.

When the contamination is considerable, as described above, the reducing agent is kneaded with a support such as flour to form a paste, which is applied to the stone surface for a certain period of time.
It must be in contact with the stone surface. Usually, it is sufficient to apply the paste-like composition in a thickness of several mm on the stone surface. Depending on various factors such as the degree of contamination of the stone, the type of stone, and the strength of the reducing agent, as well as the period of application to the surface of the stone, the heavily contaminated marble is treated with a relatively weak reducing agent as described above. Even if it does, the initial contamination will be almost eliminated if it is kept for about 3 days. In the case of holding for a long time as described above, and in the case where the application location is a place where humans can easily touch, it is desirable to cover with a resin sheet or a film as described above unless otherwise hindered.

The above-mentioned paste reducing agent may be prepared at the construction site, but may be prepared in advance and held in a closed container. The paste-like reducing agent thus prepared in advance and held in the closed container can be used as a stone material decontamination agent.

Depending on the stone, the above-mentioned reduction treatment can remove the initial contamination such as yellowing, but on the contrary, the reduction treatment may give the stone a light pink color or the like. In this case, the color generated by the reduction treatment can be removed by further performing the oxidation treatment on the stone material.
Also in this oxidation treatment, it is desirable to treat with a weak acid for a long time as a paste to protect the stone surface as described above.

As such a weak oxidizing agent, a commercially available oxygen-based bleaching agent, chlorine-based bleaching agent, hydrogen peroxide or the like can be used. Note that, depending on the combination of the reducing agent and the oxidizing agent (for example, ammonium thioglycolate and hydrogen peroxide), if mixed, the mixture may react violently. Therefore, the reducing agent is sufficiently washed out after the reducing treatment, and then the oxidizing treatment is performed. You need to be careful.

After performing the above-mentioned reduction treatment and, if necessary, oxidation treatment, the paste-like composition on the stone surface is washed away and cleaned. Through the above series of processing, the stone material that has been contaminated by yellowing or rust can be restored to its original state.

It is desirable that the stones subjected to the above treatment to remove the contamination are subjected to a treatment for preventing the subsequent contamination. However, when there is no possibility that moisture will further enter the inside of the stone material from the base portion or the like, this processing can be omitted.

Such a re-contamination prevention treatment can be carried out, for example, by applying a permeation type water absorption inhibitor to the surface of a stone. As shown in FIG. 1, the stone 10 is usually
Although there are fine gaps S between the constituent particles, the osmotic water-absorbing agent 31 penetrates into the gaps S between the particles, and without closing the gaps S, a water-repellent layer is formed on the surface thereof. To form As a result, the wettability of the inner surface of the gap S with respect to water decreases, so that the moisture of the liquid cannot pass through the gap S due to its surface tension. On the other hand, since the gap S is not closed, the gas can pass through the gap S. Therefore, the surface layer portion (the water-repellent treatment layer 30) of the stone having the water-repellent layer formed on the surface prevents the penetration of water while securing the air permeability of the stone 10. That is, while preventing the exudation of the water containing the contaminant to the water repellent treatment layer 30, the water itself remaining on the base material of the stone material 10 or inside is released to the outside as steam.
Thereby, recontamination of the stone 10 is prevented. In addition, the depth (thickness of the water-repellent treatment layer 30) through which the osmotic water-absorbing agent permeates is preferably about 3 to 5 mm.

Suitable examples of the osmotic water-absorbing agent include water-absorbing agents containing an alkoxysilane as a main component (for example, "Stone Spirits" manufactured by Kenko Kyosha Co., Ltd., "Isinol" manufactured by Navy Trading Company, etc.). ).

[0029]

【Example】

[Example 1] (Heat treatment) A part of the surface area of the stone material (Bianco Carrara having a thickness of 25 mm) of yellowish discolored building having a surface area of about 0.5 m ² was used.
At a distance of about 20 cm, a far-infrared heater ("Hi-Rex" manufactured by Hakotsu Co., Ltd .; calorific value: 3 kW) is placed, and the far-infrared rays are emitted by approximately
The part was irradiated for 5 hours to dry.

(Reduction treatment) Then, a 50% concentration of ammonium thioglycolate and rice powder are mixed to prepare a paste, and the paste composition is applied to the surface of the dried stone material to a thickness of 3 mm. Then, the top was covered with a polyethylene sheet and patted.

(Oxidation) When the compress was removed after 48 hours, the stone surface was discolored to a light reddish-yellow color. That is, the density 3
A 5% hydrogen peroxide solution and rice flour were mixed to prepare a paste, and the paste composition was applied to the discolored stone surface at a thickness of 3 mm, covered with a polyethylene sheet and subjected to compressing. After 24 hours, the compress was removed and the stone surface was washed off, and the discoloration was completely removed.

(Resoil Prevention Treatment) After that, a water-repellent treatment layer having a thickness of about 5 mm was formed by applying a permeation-type water-absorbing agent ("Stone Spirits" manufactured by Kyoiku Sanyo Co., Ltd.) to the surface of the stone material, and it was found that the treatment took 24 months. No stones were contaminated after the above.

[Example 2] Heat treatment, reduction treatment, and oxidation treatment were applied to the discolored portion of the indoor stone wall material (Bianco Carrara having a thickness of 5 mm) which turned pink due to the leaching of the adhesive in the same manner as in Example 1 above. , The discoloration was removed. Thereafter, when the surface of the stone was subjected to the re-contamination prevention treatment in the same manner as in Example 1, no contamination occurred in the stone even after 6 months or more.

Example 3 When the rust-adhered stone wall material (white granite having a thickness of 30 mm) was subjected to heat treatment, reduction treatment and oxidation treatment in the same manner as in Example 1, contamination was removed. . Thereafter, when the surface of the stone was subjected to the re-contamination prevention treatment in the same manner as in Example 1, no contamination occurred in the stone even after 6 months or more.

[Example 4] A reducing agent containing ammonium thioglycolate as a main component was applied to the surface of a dam in which contamination due to rust adhered to the entire surface, and after about 2 minutes, the surface was rubbed with water. Rust contamination was removed.

[Brief description of the drawings]

FIG. 1 is an enlarged cross-sectional view of a stone material surface to show the action of a permeation type water absorption inhibitor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Stone material 30 ... Water-repellent treatment layer 31 ... Permeation type water absorption inhibitor S ... Gap inside stone material

Claims (3)

[Claims] 1. A method for repairing contaminated stone, characterized by removing contamination on the surface of the stone by applying a reducing agent to the surface of the stone. 2. The method for repairing contaminated stone according to claim 1, wherein after the treatment with the reducing agent, the surface of the stone is further contaminated by applying an oxidizing agent to the surface of the stone. 3. A stone contamination remover characterized by kneading a reducing agent solution and a powdery water retention agent.