JP2632554B2 - Removal agent for asbestos construction layer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a treating agent for peeling and removing an asbestos layer sprayed on a surface of a structure such as a building for the purpose of heat insulation or the like. About.

(Prior Art) Recently, asbestos has been increasingly recognized as one of carcinogenic substances.

Accordingly, construction is being carried out in various places to peel off and remove the old asbestos construction layer applied to school buildings and the like.

However, since a large amount of dust-like asbestos flies around when performing this stripping work, water has been sprayed on the asbestos layer before the start of the work to wet the asbestos layer in advance.

However, with simple water, it is difficult to penetrate into the inner part of the asbestos layer having a thickness of 1 to 5 cm, and the water that has wet the bent asbestos layer is also easily evaporated in a short time. U.S. Pat. No. 4,699,666 discloses a technique in which an aqueous solution containing propylene glycol and polyethylene oxide is used as a treatment agent for stripping an asbestos applied layer.

(Problems to be solved by the invention) However, as a method of spraying the asbestos layer, gypsum is mainly used as a binder for asbestos in the United States, whereas Portland cement is used in Japan. Due to the poor water absorption of the asbestos layer, the above treatment agent has insufficient adhesion to the surface of the asbestos layer and insufficient penetration into the asbestos layer. It was difficult to make enough penetration.

Therefore, an object of the present invention is to provide a treating agent for asbestos-treated layer which has excellent adhesion and permeability and hardly evaporates even to an asbestos layer using cement as a binder.

[Constitution of the Invention] (Means for Solving the Problems) The treating agent for stripping an asbestos-worked layer according to the present invention comprises an aqueous solution of polyvinylpyrrolidone.

And the molecular weight of this polyvinylpyrrolidone is 5,000
The content is desirably in the range of at least 500,000 and the content of polyvinylpyrrolidone in the aqueous solution is desirably from 0.5 to 20% by weight.

Further, in the aqueous solution, if necessary, ethylene glycol, propylene glycol, diethylene glycol, polyhydric alcohols such as glycerin and monohydric alcohols, ketones, cellosolves, carbitols and other aqueous solutions other than polyvinylpyrrolidone. The humectant composed of a volatile organic compound is contained in the range of 0.1 to 50% by weight.

The viscosity of the aqueous solution was adjusted to 2 cps or more and 30 cps or less.

(Action) When the treatment agent for peeling the asbestos applied layer is sprayed on the surface of the asbestos layer to be peeled, the treatment agent for peeling adheres to the surface of the asbestos layer and does not drop easily.
And since this release treatment agent has excellent permeability,
During the adhesion, the asbestos layer can sufficiently penetrate into the inner part of the asbestos layer, and the entire asbestos layer can be wetted with the treating agent for peeling.

When the molecular weight of polyvinylpyrrolidone is 5.000 or less,
When the above-mentioned effect is not sufficiently obtained, and when the viscosity is 500,000 or more, the viscosity of the release treatment agent becomes too high, and both the above-mentioned effect and workability are impaired.

When the content of polyvinylpyrrolidone in the release agent is 0.5% or less, the above-mentioned effects are insufficient but cannot be obtained, and when the content is 20% or more, the effects do not increase.

Then, by including a water-soluble organic compound other than polyvinylpyrrolidone as a wetting agent, evaporation of moisture in the release treatment agent is suppressed.

When the content of the water-soluble organic compound is 0.1% by weight or less, the above effect is hardly obtained. When the content is 50% by weight or more, the solubility of polyvinylpyrrolidone in the release agent is disadvantageously reduced.

When the viscosity of the release treatment agent is 2 cps or less, the penetration of the release treatment agent into the asbestos layer is too early, and the inconvenience that the release treatment agent is absorbed into the asbestos layer construction base occurs.
If it is 30 cps or more, it becomes difficult for the peeling agent to penetrate into the asbestos layer.

(Examples) Some preferred examples of the present invention will be described below.

First Example The treatment agent for peeling was prepared by dissolving each raw material in water at room temperature by mixing the following raw materials.

Rubiscol K-30 10 (% by weight) Propylene glycol 20 (% by weight) Water 70 (% by weight) Here, Rubiscol k-30 is a polyvinylpyrrolidone manufactured by BASF, West Germany, having an average molecular weight of 40,000. Using. This polyvinylpyrrolidone is used in industrial fields such as pharmaceuticals, cosmetics, and foods, and is completely harmless in hygiene. And since it has the property of hydrogen bonding with water molecules, it plays a role in suppressing the evaporation of water from the stripping agent.

On the other hand, propylene glycol was blended as a wetting agent for suppressing evaporation of moisture from the treating agent for stripping. Prepared peeling treatment agent has a 12cps viscosity at 25 ° C., which on the basis of about 150 kg / miles ² spray pressure using airless spray gun, at about 0.5 percentage per 1 m ^2, peeling to The asbestos layer having a thickness of about 3 cm was sprayed. Then, after leaving the spraying agent for about 30 minutes after spraying to sufficiently infiltrate the asbestos layer, the stripping work was performed using a scraping tool such as a spatula. Not at all. And about 72 after the start of peeling work
Even after the passage of time, the asbestos layer was kept wet with the release treatment agent.

Prior to the start of the work, the work place was covered with a polyethylene sheet or the like in the same manner as before, and the worker put on protective equipment such as a dust mask to ensure safety.

The treatment agent for peeling the asbestos construction layer according to the composition of the above example has good permeability into the asbestos layer due to the properties of polyvinylpyrrolidone, and has an appropriate viscosity.
There was less tendency to drip from the surface of the asbestos layer after spraying as compared with the conventional one, and it completely penetrated throughout the asbestos layer having a thickness of about 3 cm. And even when the construction base of the asbestos layer was porous like cellular concrete, the amount of permeation into the construction base was small because the peeling treatment agent had an appropriate viscosity.

Second Example A treating agent for peeling was prepared by mixing the following raw materials.

Rubiscol K-90 2 (% by weight) Propylene glycol 6 (% by weight) Water 92 (% by weight) Here, Rubiscol K-90 manufactured by BASF and having an average molecular weight of 360,000 was used. The viscosity of the prepared peeling agent was 10 cps (25 ° C.). When this was used for shaking with the first embodiment, the same processing effect as in the first embodiment was obtained.

Third Example A treating agent for peeling was prepared by mixing the following raw materials.

Rubiscol K-304 (% by weight) Rubiscol K-90 2 (% by weight) Glycerin 12 (% by weight) Water 82 (% by weight) The viscosity of the prepared peeling agent was 17 cps (25 ° C.). . And the processing effect equivalent to the first embodiment was obtained.

Fourth Example A peeling treatment agent was prepared according to the following raw material composition.

Rubiscol K-308 (% by weight) Rubiscol K-902 (% by weight) Water 90 (% by weight) In this example, since the water-soluble organic compound was omitted, it was wetted with a stripping agent. Although the evaporation of water from the asbestos layer was faster than that of each of the first to third embodiments, good results were obtained in terms of permeability. Therefore, it can be used without any inconvenience under a working environment in which evaporation of water is not so fast.

The polyvinyl pyrrolidone is of course not limited to the products of BASF described above, and those having a molecular weight within the above range may be used singly or in combination of two or more kinds at an arbitrary ratio.

In addition, as the water-soluble organic compound, when odor or toxicity is not particularly a problem, monohydric alcohols such as methanol, ethanol, and isopropyl alcohol, ketones such as acetone and methyl ethyl ketone, and ethyl may be used. Cellosolves such as cellosolve, butyl cellosolve, and n-propyl cellosolve, or carbitols can also be used.

And, in order to adjust the viscosity of the release agent to a desired value, various water-soluble organic polymer compounds other than polyvinylpyrrolidone, for example, methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, starch hydrolyzate , Sodium alginate, polyvinyl methyl ether, polyvinyl methyl ether / maleic anhydride copolymer resin, polyvinyl alcohol, sodium polycarboxylate, and the like. Further, if necessary, various surfactants for increasing permeability, preservatives and the like may be blended.

[Effects of the Invention] As is clear from the above description, the treatment agent for peeling the asbestos construction layer of the present invention, which is composed of an aqueous solution of polyvinylpyrrolidone, has both appropriate viscosity and permeability, so Unlike those, when sprayed on the surface of the asbestos layer, it easily adheres to the surface and does not drip easily, and it completely penetrates deep into the thick asbestos layer using cement as a binder . And since water is hard to evaporate, especially when other water-soluble organic compounds are added in addition to polyvinylpyrrolidone, even if the required period of the stripping work is prolonged, twice as in the conventional case, As described above, it is possible to keep the asbestos layer wet without re-spraying the stripping agent, and there is almost no possibility that the asbestos may become dusty and scatter during the stripping work. In addition, since it has no toxicity, an excellent effect that workability is greatly improved can be obtained.

Claims (7)

(57) [Claims] 1. A treatment agent for stripping an asbestos construction layer, comprising an aqueous solution of polyvinylpyrrolidone. 2. The treating agent according to claim 1, wherein the molecular weight of the polyvinylpyrrolidone is 5,000 or more and 500,000 or less. 3. The treating agent according to claim 1, wherein the content of polyvinylpyrrolidone in the aqueous solution is 0.5% by weight or more and 20% by weight or less. 4. The asbestos-treating layer release treatment agent according to claim 1, wherein a water-soluble organic compound other than polyvinylpyrrolidone is contained as a wetting agent in the aqueous solution. . 5. The water-soluble organic compound is ethylene glycol,
The asbestos-treating layer release agent according to claim 4, wherein the agent is a polyhydric alcohol such as propylene glycol, diethylene glycol, or glycerin, a monohydric alcohol, a ketone, a cellosolve, or a carbitol. . 6. The treatment agent according to claim 4, wherein the content of the wetting agent in the aqueous solution is 0.1% by weight or more and 50% by weight or less. 7. The release agent for asbestos applied layers according to claim 1, wherein the viscosity of the release agent is 2 cps or more and 30 cps or less.