JPH035385A - Method for solidifying asbestos - Google Patents

Abstract

PURPOSE:To prevent the scattering of dust from sprayed asbestos without deteriorating its intrinsic performance by infiltrating an aq. alkali silicate soln. into the sprayed asbestos layer and then infiltrating a specified curing agent into the layer to solidify the layer. CONSTITUTION:An aq. alkali silicate soln. is applied and infiltrated into the sprayed asbestos layer. A curing agent contg. a polyvalent metal compd. and/or an amino acid is then applied and infiltrated into the layer to solidify the layer. The sodium silicate, potassium silicate, etc., in which the molar ratio of SiO2 to M2O (M is Na, K, Li and NH4) is controlled to 1.0-5.0 is exemplified as the silicate in the soln. to be used. A specified amt. of the curing agent is uniformly applied by spray coating, brush coating or roller coating, and the surface is pressed by a trowel or a roller, if necessary. Although the curing reaction of the surface solidifying agent rapidly proceeds at room temp. the agent can be used for about 5 hr after preparation. The agent is preferably allowed to stand for >=1 day and cured.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for solidifying asbestos, and more specifically to a method for preventing asbestos dust scattering (containment treatment) for spraying existing buildings.

(Problems to be solved by the prior art and the invention) Asbestos has excellent fire protection and fire resistance, as well as high sound absorption and
It has been widely used in construction materials due to its heat insulating properties. However, as it became known that the fine dust caused health problems such as lung cancer and mesothelioma, its use was restricted, and various methods were being considered to prevent the scattering of asbestos dust when spraying on existing buildings. has been done. In other words, although the use of asbestos is currently completely prohibited due to its tendency to generate dust, up until the 1975s, asbestos was used in buildings such as walls, ceilings, and floors, especially for machinery housing air-conditioning equipment that requires soundproofing. 2. The backs of stairs, the ceilings of parking lots, factories, etc., and pipes that require heat insulation, which have been widely constructed for the purpose of fireproofing, insulation, sound absorption, etc., remain as they are, and the amount exceeds 100,000 tons. It is said that Moreover, when spraying these existing buildings, the asbestos layer deteriorates over time, or due to damage or abrasion, it causes phenomena such as fuzzing, crumbling of fibers, and sagging, and there is a risk that the dust may be dispersed into the air. There are three methods of treatment that are appropriate depending on the situation: enclosure by covering with sheets or decorative boards (non-asbestos boards), and solidification (containment) and removal by penetrating or applying special chemicals. The project will be selected and constructed.

Regarding solidification methods, various materials and construction methods have been proposed or constructed, but evaluation criteria for the required performance after solidification are still not uniform. Each company has various problems with its characteristics, such as its fire resistance, durability, fire resistance, sound insulation, and heat insulation properties derived from asbestos, and a solidification method that fully satisfies users has not yet been developed.

(Means for Solving the Problem) In view of the above situation, the inventors of the present invention have developed a method for spraying for the purpose of preventing asbestos dust from scattering without impairing the original performance such as fire resistance of the asbestos layer. I considered it carefully. As a result, the inventors discovered that the above object can be fully achieved by using an alkali silicate-based penetrating assimilating agent alone or in combination with a penetrating assimilating agent and a surface assimilating agent as described below, leading to the completion of the present invention. .

In the present invention, spraying involves applying and permeating an aqueous alkali silicate solution to the asbestos layer, and then applying and permeating a hardening agent containing a polyvalent metal compound and/or an amino acid (hereinafter referred to as a permeation assimilation agent) to permeate and harden the asbestos layer. asbestos assimilation method, or an inorganic paint containing an aqueous alkali silicate solution and one or more selected from sub-5AR calcium, sub-5A calcium, and activated magnesium oxide as a hardening agent (hereinafter referred to as surface coating). This asbestos assimilation method is characterized by assimilating the surface by applying an assimilating agent.

The aqueous alkali silicate solution used in the permeation solidifying agent of the present invention is a salt such as sodium salt, potassium salt, lithium salt, or quaternary ammonium salt of silicic acid, and the molar ratio S i
02 /M20 (M is Na, K.

1-i represents NHa. ) is 1.0 to 5.0. The concentration of the aqueous solution can be appropriately selected depending on the thickness, density, desired strength, etc. of the asbestos layer, but usually, from the viewpoint of strength and workability, alkali silicate is 2% in terms of solid content. -30% by weight, preferably 6-24% by weight. If it is less than 2%, the strength is insufficient, and if it exceeds 30%, internal penetration is insufficient.

The polyvalent metal compound includes Groups 2 to 4 of the periodic table,
Halides, oxides, hydroxides, sulfates, sulfites of Group 6A, 7A and 8 metals.

Thiosulfates, nitrates, phosphates, condensed phosphates, especially calcium, magnesium, aluminum.

Chlorides of metals such as titanium, chromium, manganese, iron,
Water-soluble oxides and hydroxides are used, and are preferably used in the form of fine powder water dispersion or aqueous solution.

The amino acids include glycine and alanine.

9. Valine, leucine, phenylalanine, threonine, serine, proline, tryptophan, methionine. Neutral amino acids made of monoamino monocarboxylic acids such as cysteine, cystine, and aminebenzoic acid; Acidic amino acids made of monoamine dicarboxylic acids such as aspartic acid, glutamic acid, asparagine, and glutamine; lysine and hydroxylysine.

Examples include one type or a mixture of two or more types selected from basic amino acids consisting of diaminomonocarboxylic acids such as arginine and histidine. The curing agent used for the internal penetration assimilation is the polyvalent metal compound or amino acid used alone or in combination. In addition to these, a conventionally known alkali fluorosilicate may be added as a hardening agent in an amount of up to about 1%. These are 1 to 40% in terms of solid content, preferably 5 to 1%.
Used in the form of a 5% aqueous solution. If it is less than 1%, the strength is insufficient, and if it exceeds 40%, it will not penetrate internally and there is a risk of surface assimilation.

The amount of aqueous alkali silicate solution used for internal penetration varies depending on the thickness, density, and degree of adhesion to the asbestos layer of the asbestos layer, but the amount of spraying applied is usually based on the solid content per 1 omm of asbestos layer thickness. Conversion 0.1 to 1.0 kmMm
is appropriate.

The amount of curing agent used is 110.1 to 0.8k (in terms of solid content)
/ end, preferably 0.2 to 0.4 kmMm.

The surface assimilating agent used in the present invention is added to an aqueous alkali silicate solution,
An inorganic paint containing one or more selected from calcium sulfite, calcium thiosulfate, activated magnesium oxide, or an inorganic hardening agent containing calcium silicate as a hardening agent, such as Japanese Patent Publication No. 59-3839
7 or the inorganic paints described in Japanese Patent Publication No. 61-17864 are preferably used. Sodium silicate, commonly known as water glass, is an aqueous alkali silicate solution.

Examples include aqueous solutions of potassium silicate or lithium silicate. Among the hardening agents, magnesium oxide has an iodine adsorption amount of 30 to 300 m (] I /! l] M CI O
The activated one is used. The inorganic curing agent contains calcium sulfite, calcium thiosulfate, and
It is a mixture of 0 to 300 parts by weight of calcium silicate to 100 parts by weight of one or more selected active magnesium oxides, and in addition to 300 parts by weight or less of zinc oxide, silicic acid may be added as required. Magnesium acid or aluminum hydroxide.

O to 150 parts by weight of alumina, hydrated alumina, etc. can be added.

The surface assimilating agent used in the present invention is the inorganic curing agent added to the aqueous alkali silicate solution in a total amount of 30 to 30% in terms of solid content.
0[i%] was added and mixed. Calcium carbonate as an inorganic filler outside of these.

0 to 80% by weight of silica sand, pearlite, etc. in the total surface assimilating agent
It can be blended within the range of. Further, additives such as colorants, thickeners, water repellents, hardening retardants, dispersants, or leveling agents may be added in an amount of 0 to 20% by weight.

The amount of surface assimilation agent applied is usually 0.8 to 1.5k in terms of solid content.
(]/m, and if it is less than this range, it is difficult to apply it uniformly.

The method of the present invention is carried out as follows using the above-mentioned penetrating assimilating agent and surface solidifying agent.

Containment treatment was selected as the appropriate treatment method after a thorough preliminary investigation.By spraying, the asbestos layer was repaired as necessary and the coarse debris adhering to the surface was removed.

After removing oil, grease, soot, etc., first apply a predetermined amount of the aqueous alkali silicate solution for internal penetration solidification using an airless coating machine or the like, and leave it for 30 minutes or more to allow sufficient internal penetration. If necessary, press the surface with a trowel or roller. Next, the curing agent is sufficiently stirred and mixed and then applied using an airless coating machine or the like. Since the curing reaction of the osmotic assimilation agent proceeds extremely rapidly over a wide temperature range from cold to normal temperatures, it is safe to move on to the next step immediately. However, since the cured film of the surface assimilating agent of the present invention is breathable, there is no need to wait for the completion of the above reaction.

Next, the surface assimilating agent is prepared and a predetermined amount is uniformly applied to the coated surface by means of spraying, brushing, roller coating, etc., and if necessary, pressing the surface with a trowel or roller. Although the surface assimilating agent of the present invention rapidly undergoes reaction and curing at room temperature, it can be used in construction for about 5 hours after being prepared. It is desirable to leave the curing for one day or more.

(Example) The present invention will be explained in further detail with reference to Examples below. In addition, unless otherwise specified, all examples and percentages are based on weight.

Examples 1 to 13 Asbestos (chrysotile>
A mixture of 90 parts of Portland cement, 10 parts of Portland cement, and 150 parts of water was thoroughly stirred and mixed, and then applied to a thickness of 10 mm, and heated to a temperature of 48 cm.
We used an asbestos surface that had been cured for a period of time to harden.

Potash water glass (solid content 35% > 100 parts and water 100 parts)
The asbestos surface was sprayed uniformly on the asbestos surface at a solid content of 260 Mm using an airless coating machine, and after allowing it to penetrate inside for 30 minutes, calcium chloride (solid content 30%) was applied as a hardening agent. ), 5 parts of sodium silicofluoride, 30 parts of glycine, and 365 parts of water were thoroughly stirred and mixed using an airless coating machine to give a solid content of 200 parts.
The spray was applied uniformly at a ratio of g/m. Subsequently, 300 parts of potash water glass (solid content 35%), 100 parts of calcium sulfite, 80 parts of calcium silicate, and 10 parts of zinc oxide were used as surface assimilating agents.

A well-stirred mixture of 10 parts of aluminum hydroxide, 300 parts of calcium carbonate, and 30 parts of talc was applied with a spray at a solid content of 1.0 kM 7 d, and the mixture was heated at room temperature to 2.
It was left to cure for 4 hours.

Table 1 shows the results of testing the characteristics of the surface of this specimen using the following method.

Flame retardancy The results were carried out according to the test method for flame retardant grade 2 specified in JIS A 1321, and the results were expressed as smoke generation coefficient (OA>).

Hardness Test specimen as is or test specimen in water at room temperature 2
After being immersed for 4 hours and then drying at room temperature for 24 hours, the hardness of the surface of the test piece was measured in accordance with JIS K 6301 using a JISA type spring spring tester.

Adhesive strength Test specimen as is and 60'C, 95%RH
A steel attachment with a size of 1010 x 10 is glued to the surface of the specimen after repeated drying and drying 10 times, with one cycle of x 16 hours + 60'C drying x 8 hours, using epoxy adhesive, and a distance of 5 mm in the vertical direction of the surface of the specimen. The maximum tensile load (g/cm>) was measured by pulling at a speed of /min.

Impact resistance A steel ball weighing 536 g was placed at a height of 150 cm on the center of the surface of the test specimen as it was and after repeated heating and cooling 10 times with one cycle of -10°C x 24 hours + 50°C, 90% RH x 24 hours.
Maximum depth of dent caused by natural fall from cm (mm
) was measured.

Dust generation property Using a cleaning tester specified in JIS A 6909, the surface of the 4509 pressurized test piece was rubbed back and forth 300 times with a Kurobuta bristle brush, and the weight (g) of the scraped dust was measured.

Table 1 also shows the results of a test conducted in the same manner as in Example 1 using the penetration assimilation agent and surface solidification agent in the formulation shown in Table 1.

Comparative Example 1 In the same spraying as in Example 1, 100 parts of potash water glass (solid content 35%) and 100 parts of water were thoroughly stirred and mixed on an asbestos layer test piece, and an airless coating machine was used to coat the asbestos layer test piece with 260 parts (solid content equivalent).
The spray was applied uniformly at a ratio of /rri and allowed to penetrate internally for 30 minutes. The surface of this test piece was tested in the same manner as in Example 1, and the results are also shown in Table 1.

Comparative Example 2 Comparative Example 1 except that a 2-fold diluted solution of the commercially available organic internal penetration assimilation agent below with water was applied by airless painting at a ratio of 460 c/end of the original solution and allowed to penetrate internally for 5 hours.
The results of the same tests as above are also shown in Table 1.

Stock solution components Weight% Vinyl chloride vinyl acetate copolymer resin emulsion (solid content 50%) 45 Aluminum hydroxide 30 Calcium carbonate 6 Titanium dioxide 3 Additives (dispersant, preservative/antibacterial agent) 3 Water
13 Comparative Example 3 After internal infiltration assimilation treatment using an organic internal infiltration solidification agent in the same manner as in Comparative Example 2, the commercially available stock solution of Comparative Example 2 was used as an organic surface assimilation agent as it was, and 1200 g/TIi was obtained by airless painting. It was applied by spraying at a ratio of - and left to cure day and night. The surface of this test piece was tested in the same manner as in Comparative Example 2, and the results are also shown in Table 1.

From the results of the above Examples and Comparative Examples, the following can be found.

When treated only with the osmolytic agent of the present invention (Examples 8 to 1)
3) However, the test results for adhesive strength, impact resistance, and oxidation properties show that spraying sufficiently achieves the purpose of assimilating asbestos; however, by using a surface assimilating agent in combination, the oxidation properties can be completely prevented (implemented). Examples 1-7).

If the asbestos to be solidified is to be installed in a location that is subject to interior design restrictions, it is necessary to use a solidifying agent that has the required fireproofing performance, but by solidifying with the penetrating solidifying agent and surface assimilating agent of the present invention ( Examples 1 to 7) can be evaluated to be equivalent to a noncombustible material from the results of the flame retardancy test.

(Effect of the invention) The effects of the method of the present invention are as follows.

1) Spraying almost completely prevents asbestos dust from scattering.

2) When sprayed, the original functions of the asbestos layer, such as fire resistance, sound absorption, and heat insulation, are almost completely maintained.

3) In particular, the surface assimilating agent of the present invention is made of 100% inorganic components, and the solidified material is completely rendered nonflammable.

4) The solidified product obtained by the method of the present invention also exhibits excellent performance in hardness, adhesive strength, and impact resistance.

5) In particular, the solidifying agent of the present invention has excellent adhesive properties, and it adheres well to underlying concrete, mortar, and metal plywood such as steel frames and iron plates.

6) The surface assimilating agent of the present invention is chemical resistant, has air permeability, breathability, water retention and humidity control properties, and has excellent anti-mold properties.

7) In the method of the present invention, both curing agents are water-based, do not use unnecessary organic solvents, and are odorless, and both curing reactions proceed rapidly, making it possible to complete the work in an extremely short time. Moreover, it does not require any special curing and has excellent workability.

As described above, the method of the present invention exhibits extremely excellent performance in environmental conservation and is an industrially useful method.

Claims (2)

[Claims] (1) An asbestos solidification method characterized by applying and permeating an aqueous alkali silicate solution to a sprayed asbestos layer, and then applying and permeating a hardening agent containing a polyvalent metal compound and/or an amino acid. (2) Apply an aqueous alkali silicate solution to the sprayed asbestos layer and let it penetrate, then apply a hardening agent containing a polyvalent metal compound and/or an amino acid and let it harden. An asbestos solidification method characterized by surface hardening by applying an inorganic paint containing one or more selected from calcium sulfite, calcium thiosulfate, and activated magnesium oxide as an agent.