JPH02214584A - Method for preventing scattering of asbestos dust and dust treating agent - Google Patents

Abstract

PURPOSE:To prevent the scattering of asbestos dust, to increase work efficiency and to reduce working expenses by spraying an aq. soln. of fine konjak powder or a deriv. thereof on a building contg. asbestos when the building is broken or repaired. CONSTITUTION:When a building contg. asbestos is broken or repaired, an aq. soln. of fine konjak powder or a deriv. thereof is sprayed to prevent the scattering of asbestos dust. When protective colloid of sodium alginate, etc., an antiseptic such as benzoic acid and a surfactant are added to the aq. soln., the soln. is made more effective in forming gel and preventing scattering. The fine konjak powder is produced by treating konjakmannan with a chloral hydrate soln. and etherifying the treated product with monochloroacetic acid.

Description

DETAILED DESCRIPTION OF THE INVENTION 3. [Industrial Application Field] The present invention relates to a method for preventing scattering of dust generated during demolition or renovation of asbestos-containing buildings, and a treatment agent therefor.

[Conventional technology]

Because asbestos has excellent properties such as heat resistance, chemical resistance, weather resistance, and soundproofing properties, and is inexpensive, it is often used for spraying, interior materials, ceiling materials, flooring materials, and fireproof coatings for buildings and other structures. Widely used for materials etc. Especially when spraying, asbestos has a wide range of applications due to its excellent properties such as sound absorption, heat insulation, dew condensation prevention, and fire resistance. It was used as a fireproof coating for steel frames. In a social environment where many asbestos products are used, the fine needle-like fibers of asbestos are recognized as the cause of lung cancer, typified by asbestos lung disease, and malignant mesothelioma, and are considered to be harmful worldwide. There is a growing awareness of the dangers of

In Japan, as demolition work has begun on buildings that were constructed between 1955 and 1955 and used a large amount of asbestos-sprayed or asbestos-containing building materials, prevention of asbestos dust dispersion has become an important issue. ing.

The main places where asbestos is presently a problem are buildings such as schools, and asbestos is used as an exterior material for walls, ceilings, etc., taking advantage of its properties such as heat resistance and soundproofing. The current situation is that asbestos gradually peels off and scatters as the cement used as a binder deteriorates over time.

Preventing the scattering of asbestos dust is done by removing it during demolition or renovation work, and by covering or containing it during renovations. However, in Japan, there are still no standards for treatment agents or methods for preventing dust scattering.

Spraying water, which is commonly used as a measure to prevent dust scattering, is simple, but because asbestos is poorly “wetted” by water, it is difficult to penetrate inside, and once it dries, it loses its effectiveness and can cause asbestos to scatter again. occurs.

As countermeasures against this current situation, measures such as internal penetration solidification and/or surface solidification are being taken for containment, and asbestos treatment agents have also been developed in line with this usage situation, and most of them contain asbestos in building materials. This is a combination of a surfactant that is added to blend well with asbestos, and a water-based paint that takes worker safety into consideration.

The main component of water-based paints is a resin component similar to that of oil-based paints, and a functional group that is easily compatible with water has been introduced at the end so that it can be dissolved in water. Because of this structure, the fine mist generated by spraying water-based paint can relatively easily enter a dry state similar to that of conventional resin. It is not enough to trap and remove it inside. In addition, water-based paint that has solidified on the surface generates new dust during the process of peeling off, transporting, and final disposal, causing secondary pollution.

The goal of future dust countermeasures is to remove dust floating in the air, including during demolition and renovation work.

Asbestos spraying has been prohibited since 1975, but in recent years as buildings have aged, changes in use and functionalization have been promoted, and demolition and renovation of buildings is expected to increase in the coming years. It can be fully predicted that asbestos dust will be generated and dispersed during this process.

[Problem to be solved by the invention]

Therefore, the present invention is intended to prevent the scattering of asbestos dust generated by the demolition and renovation of the above-mentioned buildings, to provide non-hazardous safety measures for workers engaged in demolition and renovation, to prevent pollution from using chemicals, to prevent general environmental pollution, and to treat chemicals. The purpose of the present invention is to provide a method for preventing asbestos dust scattering that is appropriate and practical from a comprehensive standpoint such as cost, and a treatment agent for the same.

[Means to solve the problem]

The present invention is a method for dismantling or renovating buildings containing asbestos and preventing the scattering of generated dust by spraying an aqueous solution of fine konjac powder or its derivatives to form a film on the surface of the building. This is achieved through prevention methods.

[Effect]

The konjac powder used in the present invention is also called glucomannan or konjac mannan, as described in the ground solidification method (Japanese Patent Publication No. 56-21780) already disclosed by the present applicant. Glucose (Call+zOi) and Mannose (C&H1□06
), which when hydrolyzed yields two molecules of mannose and one molecule of glucose.

In other words, konjac mannan has one or more (often several) alcohol groups (OH) and - aldehyde groups (
C) To) or a polycondensate of glucose and mannose having a ketone group (CO). This konjac mannan (indicated by R-OH) was pretreated with a 20% solution of bubble water chloral, and then etherified using monochloroacetic acid as shown in the following formula: % formula % to produce a konjac mannan derivative. can be used as a processing agent in the method of the present invention.

Spraying occurs when asbestos fibers protrude from the surface as the asbestos deteriorates over time, and a large amount of dust is generated during wind pressure, vibration, or when buildings are dismantled, demolished, or crushed.

In the method of the present invention, 0.
When spraying a slightly acidic treatment agent made of an aqueous solution of powdered konjac powder with a concentration of around 2 to 2χ, this treatment agent causes a mild neutralization reaction with the alkaline components of cement, the main building material, and damages the surface of the building. It penetrates the sprayed asbestos layer and turns into a gel, and even if there is no continuous supply of aqueous solution, it reacts with the salts (mainly calcium salts) inside the surrounding cement, forming a stable coating on the surface by coagulation. It is known that this aqueous solution of fine konjac powder turns into a gel by adding an alkaline coagulant or the like.

Therefore, in the present invention, since the asbestos material to be treated is alkaline, in some cases it is not necessary to add a coagulant when preparing the treatment agent (rather, it is not necessary to add an acid or a buffering agent). Preferable results can also be achieved by adjusting the pH to a predetermined weakly acidic range.

In addition, this aqueous solution of konjac powder shows good "wetness" to asbestos, so penetrating coagulation occurs effectively.
Even under dry conditions after gelation, the konjac powder solution maintains good water retention, and even when the water dries, the asbestos fibers are stably captured and fixed in the konjac mannan and do not scatter.

In this way, konjac flour has a good "wetness" to asbestos and therefore has a good absorption rate, so the concentration in the aqueous solution is 0.
．． An excellent anti-scattering effect can be obtained even when the concentration is around 2χ to 2χ, and in some cases, a concentration in the range of around 0.4χ to 0.7χ is also effective.

Of course, the present invention also includes adding an appropriate amount of a protective colloid to the konjac flour or its derivative used in the present invention. Examples of protective colloid agents include cellulose sodium glycolate (C5M,S), starch sodium glycolate J, (C0M,S), methyl cellulose, methyl starch, glucosol, as disclosed in the above-mentioned patent of the present applicants. Nodeltalactone (C:, D.

L.) Carrageen, sodium polyphosphate, sodium alginate, etc. are suitable, and one or more of them are used in combination. The amount added is 0.1% to 10% of the product.
In particular, it is in the range of 0.3χ to 1.5χ. These protective colloid agents have excellent protective colloidal film-forming properties, stability, viscosity, etc., and can improve the colloidal or gel-like composition of konjac flour or its derivatives, sodium silicate-based chemicals, and cement suspensions. This enables homogeneous co-coagulation of the two, thereby forming a gelled product with good stability and shape retention.

Preservatives are effective in preventing deterioration and spoilage of organic konjac powder, which is the processing agent, and include benzoic acid and its sodium salt, sorbic acid and its potassium salt, paraoxybenzoic acid, propionate calcium or sodium salt, etc. A known preservative selected from the group consisting of preferably 0.3 to konjac mannan as the main ingredient.
It is added in a range of χ to 1.5χ.

Surfactants have been conventionally used for their penetrating action and prevention of dust scattering, and in the present invention, surfactants are also used in the present invention, such as anionic surfactants such as alkylbenzene sulfonates (ABS) and non-ionic surfactants such as alkyl allyl ethers. An ionic surfactant can be used in combination with konjac mannan as the main ingredient in an amount of 0.3 to 1.5χ. In this specification, the cement described as the main component of the building material includes not only the so-called cement itself but also the cement mixed with an appropriate aggregate and applied by coating. Furthermore, although the method of the present invention is extremely effective in preventing the scattering of asbestos dust, it can be similarly applied to preventing the scattering of other dusts that can be collected by gelling an aqueous solution of fine konjac powder. The present invention will be further explained below with reference to Examples.

Example 1 5 g of konjac flour was added to 1,000 cc of tap water, slowly stirred, and left for 2 hours. p of solution
The H value is 6.50, which is weakly acidic, and it is a desirable requirement that the mannan solution used be weakly acidic, considering that the material used for asbestos spraying is cement (alkali). .

Asbestos (reagent) was spread in a petri dish (diameter 9c+w), placed in a 400r vessel offshore to generate airflow with an internal fan, waited for the asbestos concentration to stabilize for 2 hours, and the concentration at this time was taken as the initial concentration.

35 cc of the 0.5% mannan solution prepared as described above was sprayed into a 400 F container, and asbestos dust was collected after 1 and 48 hours and measured using a phase contrast optical microscope. As shown below, excellent results have been obtained, and its effectiveness is equivalent to or even better than that of Serviflex (trade name of a Selby product in France), which is currently known as the best asbestos treatment agent. there were.

First w1a degree 124 f/I! After 1 hour 14 # After 48 hours 8 〃 Example 2 For spraying, asbestos fragments were ground up, dust was generated in the same manner as in Example 1, and the asbestos concentration was dispersed for 2 hours, and when the asbestos concentration stabilized, it was determined as the initial concentration. did.

Asbestos concentration was measured in the same manner as in Example 1.

Initial concentration 139 f/i! After 1 hour 37 After 48 hours 12 〃 Example 3 A sample was prepared by roughly scraping the top surface of 72.3 cm of massive asbestos on another concrete surface to generate fine dust. The FNfi degree was measured. Thereafter, the mannan solution was sprayed onto the lumps, and the dust was generated in the same manner as above, and the concentration was measured.

Initial concentration 453 1712 After 1 hour 73 After 48 hours 56 Comparative example Using the same lump asbestos as in Example 3, water was sprayed instead of the X-nannan solution, and the asbestos concentration was measured in the same manner as in Example 3.

Initial concentration 92 r/1 Immediately after spraying 22 〃 After 1 hour 15 〃 After 20 hours 61 〃 From the results of the above comparative example, the asbestos collection effect by water spray decreases over time, and this is due to the asbestos being removed by drying. This is due to re-dispersion, and simple water spraying is not sufficient as a countermeasure against asbestos dust.

Mannan solution absorption test for lump asbestos In order to determine the required amount of konjac mannan solution to prevent asbestos dust scattering, the absorbed amount of the 0.5% konjac mannan solution used in each of the above examples per unit volume of lump asbestos was determined. Ta.

Mannan solution 5 cc/4 cd-1,22cc
/ cd water 3 cc / 5 aj-
+0.61cc/aj The property that asbestos is difficult to get wet with water is also reflected in this result. The reason why the amount of mannan solution absorbed exceeds the volume of the asbestos piece is because the mannan solution wets the surface uniformly and does not drip easily.
This is one of the effective characteristics when used in actual asbestos countermeasures.

Based on the experimental results of these examples, the concentration of the aqueous solution of the konjac flour of the present invention or its derivatives is 0.2 to 2χ,
Preferably it was 0.4 to 0.7χ.

(Effects of the Invention) According to the present invention, it is possible to effectively prevent asbestos dust from scattering during the demolition and renovation of buildings.

In addition, its permeability prevents dust from forming inside the asbestos layer, which is insufficient even with water spraying, and improves work efficiency and costs, such as eliminating the need to spray additional chemicals as the work progresses during stripping and removal work. can be measured at low cost.

Claims (4)

[Claims] (1) A method for preventing the scattering of asbestos dust, which is characterized by spraying konjac fine powder or an aqueous solution of its derivatives onto the structure, in a method for preventing the scattering of dust generated during the demolition or renovation of buildings containing asbestos. Method. (2) For the aqueous solution, a protective colloid agent, a preservative,
Claim 1 wherein an auxiliary agent such as a surfactant and/or a surfactant is added.
Method described. (3) A treatment agent for preventing scattering of asbestos dust consisting of an aqueous solution of fine konjac powder or its derivatives. (4) The treatment agent according to claim 3, wherein an auxiliary agent such as a protective colloid, a preservative, and/or a surfactant is added to the aqueous solution of fine konjac powder or a derivative thereof.