JPH02258682A - Method for treating asbestos-containing object - Google Patents

Abstract

PURPOSE:To prevent asbestos from scattering and improve surface characteristics by treating an asbestos-containing object with a flame retardant resin composition composed of a specific composition and ammonium polyphosphate. CONSTITUTION:About 100 pts.wt. polymerizable monomer (e.g. alkyl alpha,beta- monoethylenically unsaturated carboxylate) is subjected to emulsion polymerization in the presence of 10-400 pts.wt. (expressed in terms of solid substance) colloidal silica having 4-100mum particle diameter in an aqueous system using an anionic surfactant to provide a water-dispersible resin composition (A) which is an aqueous polymer latex. The component (A) is then mixed and dispersed in ammonium polyphosphate in an amount of 10-200wt.% based on the solid substance of the component (A) to afford a flame retardant resin composition (B). The component (B) is then applied to an asbestos-containing object, such as sprayed asbestos, prepared by spraying asbestos and cement so as to provide >=10g/m<2> solid content of the component (B). The coated object is subsequently dried at 5-100 deg.C for 10-20min to produce a treated product which is the asbestos- containing object.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a new and useful method for treating asbestos-containing objects. More specifically, the present invention uses a flame-retardant resin composition consisting of a water-dispersible resin composition obtained by emulsion polymerization of a polymerizable ester in the presence of colloidal silica, and ammonium polyphosphate. The present invention relates to a new treatment method for preventing asbestos scattering, comprising:

[Conventional technology]

Asbestos itself is nonflammable, has excellent strength and electrical insulation, and has a good affinity with cement, so asbestos can be used alone or mixed with cement. It has been widely used as a noncombustible building material, thermal insulation material, and soundproofing material.

However, as these asbestos-containing objects deteriorate over time, the asbestos fibers are exposed, and asbestos mist is scattered and suspended, causing harm to human health. It is common knowledge that this is a social problem.

As a measure or measure to prevent the scattering of asbestos, many studies have been made to date on methods of treating asbestos-containing objects with resins or compounds.

For example, various organic polymers such as polymer latex, epoxy resin or urethane resin are used,
This involves using various inorganic compounds such as silicate compounds.

[Problem to be solved by the invention]

However, each of the above-mentioned scattering prevention methods has drawbacks and cannot be said to be fully satisfactory.

In other words, in methods using organic polymers,
There is a problem that the adhesion to asbestos cement is poor and it peels off over time, eventually losing its anti-scattering effect.Furthermore, solution-type resins that use organic solvents as solvents or diluents have problems. When processing this solution-type resin indoors, there are problems such as the danger of fire and explosion, stability and hygiene issues such as exhaust, and handling problems.

Furthermore, although conventional water-dispersible resins such as polymer latex have fewer problems in terms of handling than the above-mentioned solution-type resins, from the viewpoint of film formation, they do not require too hard polymers. As a result, it cannot be used
The drawback is that after treatment and drying, asbestos-containing objects remain sticky and their stain resistance is reduced.

Furthermore, each of the above-mentioned dry films, whether they are solution-type resins or water-dispersible resins, is a kind of organic material called resin (organic polymer), and due to its nature, it easily burns and burns out. Therefore, the intended effect of using non-combustible asbestos can be halved.

On the other hand, methods using inorganic compounds have excellent adhesion to asbestos cement, stain resistance, and nonflammability, but the inorganic compounds themselves are brittle and have excellent properties. Because it is a physical object, it has the disadvantage of being easily destroyed by external impact.

As described above, it can be said that all conventional methods for treating asbestos-containing objects are insufficient.

However, as a result of intensive studies aimed at solving and eliminating the various drawbacks and problems in the prior art as described above, the present inventors have developed a method of emulsion polymerization of polymerizable monomers in the presence of colloidal silica. The resulting water-based polymer latex (water-dispersible resin composition) has excellent adhesion to asbestos-containing substances, and forms a treated film with excellent properties such as adhesiveness, blocking resistance, and impact resistance. Having discovered this, they have filed an application for a method for treating asbestos-containing objects, which involves using such a water-dispersible resin composition. (Tokugan Sho 6
3-182828) Furthermore, the present inventors have developed a resin composition obtained by dispersing ammonium boIJW acid into such a specific water-dispersible resin composition prepared by emulsion polymerization in the presence of colloidal silica. The present invention was completed by discovering that the product itself has good stability and also has good flame retardancy.

Thus, the problem to be solved by the present invention is to improve adhesion, impact resistance, and resistance to asbestos-containing objects, which could never be achieved using conventionally known treatment methods for this type of asbestos-containing objects. The objective is to realize blocking properties (stain resistance), flame retardance, and storage stability, and to develop an effective method for treating asbestos-containing objects.

[Means to solve the problem]

Therefore, the present invention provides a flame-retardant resin composition obtained by subjecting a polymerizable monomer to emulsion polymerization in the presence of colloidal silica, and then dispersing ammonium poly-JW acid into the thus obtained water-dispersible resin composition. It is an object of the present invention to provide a method for treating asbestos-containing objects, which comprises using asbestos-containing objects.

Here, first, the water-dispersible resin composition described above has film-forming ability (film-forming performance) at a temperature around room temperature.
There is no particular restriction, and any name can be used as long as it has the following.

In general, this type of aqueous polymer latex is produced by appropriately combining hard monomers such as methyl methacrylate and styrene with soft monomers such as ethyl acrylate, butyl acrylate, vinyl acetate, or ethylene. It is prepared so that the temperature is about 40 to 50°C or lower.

More specifically, the water-based polymer TEX, which is the water-dispersible resin composition used in the method of the present invention, is composed of α,β-monoethylenically unsaturated saturated carboxylic acid alkyl ester, β , β-monoethylene saturated carboxylic acid (hereinafter also referred to as acrylic monomer).

), styrene alkenylbenzene, and other polymerizable monomers are emulsion polymerized in an aqueous system.

In the present invention, preferably 10 to 400 parts by weight (in terms of solid content) of colloidal silica are added to the anionic surfactant and (Or) An aqueous polymer latex obtained by emulsion polymerizing these components in an aqueous system in the presence of a nonionic surfactant is preferable.

Here, examples of the acrylic monomer include esters of (meth)acrylic acid and alkanols having a carbon number of 1 to 18, among which representative ones include methyl (meth)acrylate, Ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, 2-(meth)acrylate
Ethylhexyl, (meth)decyl acrylate, (meth)
Examples include dodecyl acrylate and 2-hydroxyethyl (meth)acrylate.

Examples of the acrylic monomer include polymerizable unsaturated carboxylic acids such as (meth)acrylic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, and itaconic acid.

Representative alkenylbenzenes mentioned above include:
Examples include styrene, α-methylstyrene, and vinyltoluene.

To carry out the process of the present invention, the above listed α, β-monoethylenically unsaturated carboxylic acid alkyl ester, β, β-monoethylenically saturated carboxylic acid, and alkenylben, respectively, are required as essential monomers. Emulsion polymerization may be carried out by a conventional method using such essential monomers and other known and commonly used vinyl monomers having copolymerizability.

In the present invention, in the emulsion polymerization of the above polymerizable monomer, divinyldimethoxysilane, divinylbis-β-methoxy-ethoxysilane, vinyltrinidoxysilane, vinyltris-β-methoxy-nidoxysilane or T-methacryloxypropyl trisilane is used. When used in combination with a silane monomer having both a polymerizable unsaturated bond and an alkoxysilane group, such as a di- or trialkoxysilane compound such as methoxysilane, the compatibility between the organic polymer and the inorganic substance can be improved. , a more stable aqueous polymer latex can be obtained, and the durability of the coating film can also be improved.

The above-mentioned colloidal silica refers to an aqueous dispersion having 5i02 as a basic unit, and particularly a particle size of 4 to 100 μm. Any of these can be used and can be selected as appropriate depending on the conditions during emulsion polymerization.

Among these, the representative colloidal silica on the acidic side is Snowtex OJ (product of Nissan Chemical Industries, Ltd.), while the colloidal silica on the basic side is Snowtex 20, 30, 40°C and N.J.
(product of the same company) is a typical example.

The aqueous polymer latex obtained by emulsion polymerization of the above-mentioned polymerizable monomers, such as acrylic monomers, in the presence of colloidal silica has the flexibility, film-forming properties, and transparency of acrylic polymers, and the flexibility, film-forming properties, and transparency of colloidal silica. Hardness, temperature sensitivity, heat resistance, chemical resistance,
It was recognized that the characteristics of both types coexist, such as solvent resistance and adhesion. The reason why the above features can be combined is not necessarily clear, but during emulsion polymerization, the OH groups on the surface of colloidal silica react with acid monomers and silane monomers, resulting in cross-linking. - It is believed that an inorganic hybrid water-dispersible composition is formed.

The 0)1 groups on the surface of colloidal silica further react with the OH groups present on the surface of the inorganic base material, which is an asbestos-containing object, and form a crosslinking bond, thereby forming an organic-
This is thought to be due to the formation of a strong inorganic composite film.

When the amount of colloidal silica is less than 10.0 parts by weight relative to 100.0 parts by weight of the various polymerizable hexamers described above,
It is difficult to achieve the effect of forming a strong organic-inorganic composite film, and as a result, the features of colloidal silica such as hardness, heat resistance, chemical resistance, solvent resistance, and adhesion are reduced. On the other hand, if the amount exceeds 400.0 parts by weight, the flexibility of the acrylic polymer may decrease or a continuous film may not be formed, which is not preferable.

As the ammonium polyphosphate used in the present invention, commercially available ammonium polyphosphate is sufficient, and specific examples include "Exorisoto 422J (Hoechst Japan ■ product)" and "Sumisafe PJ (Suminami Kagaku Kogyo ■ product)" etc.

The addition ratio of the ammonium polyphosphate is 10 to 200% by weight based on the solid content of the aqueous polymer latex.
It is preferable to fall within the range. If the amount added is less than 10% by weight, the flame retardancy will decrease, while if it is added too much, exceeding 200% by weight, the viscosity of the compounded composition will increase and handling will become difficult. Either case is unfavorable since the storage stability of the composition may decrease and aggregation may occur during long-term storage.

The thus obtained flame-retardant resin composition may or may not contain a pigment.

As such pigments, any conventionally known pigments can be used. However, the most representative ones include titanium oxide, calcium carbonate, barium sulfate,
Inorganic pigments such as carbon black, red lead or yellow lead; or organic pigments such as ab-based, phthalocyanine-based or quinacridone-based pigments.

Furthermore, the flame-retardant resin composition may optionally contain various additives used as additive components for ordinary paints, such as plasticizers, dispersants, thickeners, solvents, preservatives, or antifoaming agents. There is no problem in using a mixture of additives.

Furthermore, there is no problem in using a carbonizing agent or a blowing agent such as pentaerythritol or melamine powder, which are commonly used as adjuvants for flame retardant formulations.

When implementing the treatment method of the present invention, the asbestos-containing object to be treated is a mixture of asbestos and cement, as well as a binder, etc., and sprayed onto wood, concrete, metal, etc. sprayed asbestos; asbestos board or asbestos paper made by mixing asbestos and cement with perlite, calcareous material, or calcium silicate, or having a decorative surface treatment; or asbestos and diatomaceous earth, perlite, cement, or vermiculite. It is a mixture of
Typical examples include heat insulating materials, soundproofing materials, asbestos pipes, pulp cement boards, etc. shaped into plates or cylinders.

As a specific method of the method of the present invention, that is, a treatment method using the flame-retardant resin composition, a conventional painting method is adopted, such as a spray method,
Examples include brush coating or roll coating, and there is also a method in which asbestos-containing objects are immersed in a flame-retardant resin composition.

The asbestos-containing object coated or impregnated in this way is usually cured by drying it at room temperature for several hours, but at a temperature of about 50 to 100 degrees Celsius it is hardened.
It is also possible to dry for ~20 minutes. In this case, as for the amount of flame retardant resin composition used, there is no problem as long as the solid content in the composition is high, but if the solid content is less than 10 g/rd, asbestos fibers This is undesirable because the adhesion strength of the material decreases.

〔Example〕

Next, the present invention will be explained by reference examples, examples, and comparative examples.
Although the layers will be specifically explained, the present invention is not limited to these examples.

In addition, in the following, unless otherwise specified, parts and percentages are
All are based on weight.

First, a commercially available asbestos-containing spray material was sprayed onto concrete to a thickness of 2 cm, the surface of which was troweled, and the material was cured for one month to be used as a base material.

Reference example 1 (Preparation example of aqueous polymer latex) (1)
Polymerizable monomers 2-ethylhexyl acrylate 50 parts Methyl methacrylate 48 Acrylic acid
2 (2) Surfactants Sodium lauryl sulfonate 3 parts (3)
Colloidal silica "Snowtex 30" (solid content = 30%) 100 parts 178.3 (4) Ion-exchanged water (5) Polymerization initiators Ammonium persulfate 0.5 parts Sodium hydrogen sulfite 0.2 In a four-way flask , a surfactant, colloidal silica, and ion-exchanged water were charged, the temperature was raised to 60°C in a nitrogen stream, then a polymerization initiator was added, and a mixture of polymerizable monomers was added dropwise over a period of 3 hours. However, the reaction temperature at this time was 3
The temperature was adjusted to a range of 0 to 70°C.

After the completion of the dropwise addition, the reaction is continued under stirring while maintaining the same temperature range for 2 hours, and then the mixture is cooled and the pt+ is adjusted to 8 to 9 with about 14% aqueous ammonia, so that the solid content becomes 35%.
The desired stable aqueous polymer latex was obtained.

Reference Examples 2 and 3 (Same as above) A stable aqueous polymer latex was obtained in the same manner as in Reference Example 1, except that the charging ratio of each raw material component was changed as shown in Table 1.

Reference Examples 4 and 5 (Example of Preparation of Comparative Water-Dispersible Composition) A control sample was prepared in the same manner as Reference Example 1, except that the charging ratio of each raw material component was changed as shown in Table 1. An aqueous polymer latex was obtained.

Turtle U Examples 1 to 3 20 parts of "F-Solid 422" was blended with 100 parts of the aqueous polymer latex obtained in Reference Example 1, and stirred and dispersed at 2000 rpm for 5 minutes using a Lab Disper. A flame retardant resin composition of the present invention was obtained.

Next, this flame-retardant resin composition was applied to the above-mentioned base material using air spray so that the solid content was 150 g/rrr, and dried at room temperature for one week to achieve the desired asbestos content. A processed product of the object was obtained.

In parallel, "F-Solid 4" was added to 100 parts of the aqueous polymer latex obtained in Reference Examples 2 and 3.
22" were mixed and dispersed in 30 parts and 50 parts, respectively, in the same manner as in Example 1 to obtain the desired treated asbestos-containing object by painting and drying. .

Comparative Example 1 The aqueous polymer latex obtained in Reference Example 1 was used as it was,
With air spray, solid content is 150g/
rrr and dried at room temperature for one week to obtain a treated asbestos-containing object for control.

Comparative Examples 2 and 3 Aqueous polymer latex 1 obtained in Reference Examples 4 and 5
A control product containing an asbestos-containing object was obtained by coating and drying in the same manner as in Example 1, except that 20 parts of "Exorit 422" was blended and dispersed relative to 00 parts.

Comparative Example 4 “Ethyl silicate 40” [Silicate compound manufactured by Colcote ■, which is a partial hydrolysis of ethyl silicate]
was applied to the above-mentioned base material by air spraying to give a solid content of 150 g/
rrr and dried at room temperature for one week to obtain a treated asbestos-containing object for control.

and storage stability were evaluated.

The results are summarized in Table 2.

The adhesive strength, impact resistance, blocking resistance, and flame retardance of the treated objects of Examples 1 to 3 and Comparative Examples 1 to 4 prepared as described above were evaluated as follows. .

(1) An axotiment with an adhesive strength of 4 x 4- was attached to a treated substrate using an epoxy adhesive, and measured using a Kenken type adhesion tester.

(2) Impact resistance treatment A 500 g iron ball was dropped onto the surface of the substrate from a height of 50 cI11, and the state of destruction, peeling and chipping of the treatment agent was comprehensively judged by visual inspection.

(3) Anti-blocking treatment The level of stickiness on the surface of the substrate was determined by the touch of the hand.

(4) The flame retardant treated base material was burned using an alcohol lamp, and the continuity of combustion and the state of the flame were comprehensively judged by visual observation.

(5) Storage stability of the formulation 450g of the formulation was placed in a 500cc glass bottle and heated to 23°C.
After being left at room temperature for one week, the state of aggregation and thickening was comprehensively judged by visual observation.

As is clear from Table 2, the treatment method of the present invention is extremely excellent in all aspects of adhesive strength, impact resistance, blocking resistance (staining resistance), flame retardance, and storage stability. , and it can be seen that these performances are well balanced.

〔Effect of the invention〕

The specific flame-retardant resin composition used in the present invention to treat various asbestos-containing objects exhibits excellent adhesion to asbestos-containing objects, as well as impact resistance and blocking resistance (stain resistance). It is possible to form a film with flame retardancy and storage stability.

Therefore, the treatment method of the present invention can effectively prevent asbestos from scattering from asbestos-containing objects for a long period of time, and can provide asbestos-containing objects with excellent surface properties.

Agent: Patent Attorney Katsutoshi Takahashi

Claims (1)

[Claims] 1. An asbestos-containing object characterized by using a flame-retardant resin composition consisting of a water-dispersible resin composition obtained by emulsion polymerization of a polymerizable monomer in the presence of colloidal silica and ammonium polyphosphate. processing method.