JPH0234586A - Treatment of body containing asbestos - Google Patents

Abstract

PURPOSE:To form a coating film having superior adhesive strength, shock and blocking resistances on a body contg. asbestos by preparing specified aq. polymer latex by emulsion polymn. in the presence of colloidal silica. CONSTITUTION:A polymerizable monomer, e.g., a combination of a hard monomer such as methyl methacrylate with a soft monomer such as ethyl acrylate is emulsion-polymerized in the presence of colloidal silica to prepare aq. polymer latex. This latex is preferably prepd. by adding about 10-400 pts.wt. (expressed in terms of solid matter) colloidal silica to 100 pts.wt. (expressed in terms of solid matter) polymerizable monomer and carrying out emulsion polymn. in the presence of an anionic surfactant and/or a nonionic surfactant. A body contg. asbestos is coated with the polymer latex by means of an air spray, etc., to form a film by about 150g/m<2> (expressed in terms of solid matter) thickness.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a novel treatment method for preventing asbestos scattering. The present invention relates to a method for treating asbestos-containing objects characterized by using a water-dispersible polymer latex obtained by polymerization (hereinafter referred to as water-based polymer latex).

(Prior art) Asbestos has properties such as nonflammability, strength,
Because it is a material with excellent electrical insulation and good affinity with cement, it has been sprayed or molded alone or mixed with cement, and has been widely used as a noncombustible building material, heat insulation material, and soundproofing material. .

However, as these asbestos-containing objects deteriorate over time, asbestos fibers are exposed and scattered, causing health problems, and it is well known that this has become a social problem as so-called asbestos pollution.

As a countermeasure to prevent asbestos from scattering, methods of treating asbestos-containing objects with resins or compounds have been studied.1 For example, polymer latex, epoxy resin,
Methods using organic polymers such as urethane resins or inorganic compounds such as silicate compounds are known.

(Problems to be Solved by the Invention) However, all of these methods have drawbacks and are not fully satisfactory.

That is, in the case of organic polymers, there is a problem that they have poor adhesion to asbestos cement, and that they peel off over time and lose their effectiveness. Furthermore, when processing solution-type resins that use organic solvents as solvents or diluents indoors, there are risks of fire and explosion, and health and safety issues such as exhaust emissions.

Or there are handling problems.

In addition, conventional water-dispersible resins such as polymer latex are easier to handle than solution-type resins, but from the viewpoint of film formation, it is not possible to use very hard polymers, and processing, There is a drawback that stickiness remains on asbestos-containing objects after drying, reducing stain resistance.

Furthermore, inorganic compounds have excellent adhesion and stain resistance, but have the disadvantage of being easily destroyed by external impact due to their brittle nature.

Either method is insufficient as a treatment method.

However, as a result of intensive studies by the present inventors in order to solve the various drawbacks or problems in the prior art described above, it has been found that a specific aqueous polymer latex prepared by emulsion polymerization in the presence of colloidal silica can be used for asbestos-containing objects. The present invention has been completed by discovering that a treated film can be formed with excellent adhesion, blocking resistance, and impact resistance. [Structure of the invention] (To solve the problems Means) To summarize the present invention, the present invention relates to a method for treating asbestos-containing objects characterized by using an aqueous polymer latex obtained by emulsion polymerization of a polymerizable monomer in the presence of colloidal silica.

Hereinafter, the configuration of the present invention will be explained in detail.

The aqueous polymer latex obtained by emulsion polymerization of a polymerizable monomer in the presence of colloidal silica used in the present invention may be any polymer latex as long as it has film-forming ability at around room temperature.

Generally, this type of aqueous polymer latex is made by appropriately combining hard monomers such as methyl methacrylate and styrene with soft monomers such as ethyl acrylate, butyl acrylate, vinyl acetate, and ethylene.
More specifically, the aqueous polymer tex of the present invention is prepared such that the minimum film forming temperature) is about 40 to 50°C or less. Saturated carboxylic acid alkyl ester and α.

Obtained by emulsion polymerization of monomers selected from β-monoethylenically unsaturated carboxylic acids (hereinafter referred to as acrylic monomers), alkenylbenzenes such as styrene, and other polymerizable monomers in an aqueous system. It is something that can be done.

In the present invention, preferably 10 to 4 parts by weight of colloidal silica are added to 100 parts by weight (in terms of solid content) of the monomers described above.
An aqueous polymer latex obtained by emulsion polymerizing 00 parts by weight (in terms of solid content) in an aqueous system in the presence of an anionic surfactant and/or a nonionic surfactant is preferable.

Here, examples of the acrylic monomer include esters of (meth)acrylic acid and alkanols having 1 to 18 carbon atoms, among which a typical example is methyl (meth)acrylate (meth)acrylate. Ethyl acid, n-butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate or 2-hydroxy (meth)acrylate Ethyl etc. are revived.

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.

In the present invention, divinyldimethoxysilane, divinylbis-
Polymerizable unsaturated bonds and alkoxysilane groups such as di- or trialkoxysilane compounds such as β-methoxy-ethoxysilane, vinyltrinidoxysilane, vinyltris-β-methoxy-nidoxysilane or γ-methacryloxypropyltrimethoxysilane. When the contained silane monomer is used in combination, 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 of SiO□ as a basic unit, particularly one having a particle size of 4 to 100p. Any of them can be used and can be appropriately selected 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)," 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 above polymerizable monomer in the presence of colloidal silica,
For example, aqueous polymer latex obtained by emulsion polymerization of acrylic monomers has the flexibility of acrylic polymers,
Film-forming properties, transparency, hardness and temperature sensitivity of colloidal silica.

It was found that it has the characteristics of both, including heat resistance, chemical resistance, 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 to form crosslinking bonds, and as a result, organic- It is believed that an inorganic hybrid water-dispersible composition is formed.

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

If the amount of colloidal silica is less than 10.0 parts by weight with respect to the above-mentioned ioo, o parts by weight of the polymerizable monomers, the effect of forming a strong organic-inorganic composite film will not be exhibited, and the hardness, heat resistance, and chemical resistance will be reduced. , the features of colloidal silica, such as solvent resistance and adhesion, deteriorate. On the other hand, if it exceeds 400.0 parts by weight, the flexibility of the acrylic polymer decreases and a continuous film cannot be formed.

The aqueous polymer latex of the present invention may or may not contain a pigment.

As the pigment, any conventionally known pigment can be used.

For example, titanium oxide, calcium carbonate, barium sulfate,
There are inorganic pigments such as carbon black, red lead, and yellow lead, and organic pigments such as azo pigments, phthalocyanine pigments, and quinacridone pigments.

Furthermore, the aqueous polymer latex of the present invention further contains a plasticizer, a dispersant, a thickener, a solvent, and a preservative as required.

It is also possible to mix and use additives such as antifoaming agents that are commonly used as components for paints.

Asbestos-containing objects to be treated by the present invention include sprayed asbestos that is a mixture of asbestos, cement, and other binding materials and is sprayed onto wood, concrete, scrap metal, etc.; asbestos and cement, perlite, calcareous materials, and Asbestos boards and asbestos paper mixed with calcium chloride, etc., and made into paper or with a decorative finish on the surface; Heat insulating material made of a mixture of asbestos, diatomaceous earth, perlite, cement, vermiculite, etc., and formed into plate or cylindrical shapes. .

Examples include soundproofing materials, asbestos pipes, and pulp cement boards.

As a specific treatment method using the aqueous polymer latex of the present invention, a conventional coating method is adopted, such as a spray method, a brush coating method,
Examples include roll coating, and there is also a method of immersing the asbestos-containing object in an aqueous polymer latex.

In this way, asbestos-containing objects coated or impregnated with
Usually, it is cured by drying at room temperature for several hours, but it is also possible to dry at a temperature of about 50 to 100°C for 10 to 20 minutes. In this case, there is no problem with the amount of water-based polymer latex used if the solid content is high in the latex, but if the solid content is 10 g 7 m
If it is less than that, the adhesion strength of asbestos fibers decreases, which is not preferable.

〔Example〕

Hereinafter, the present invention will be explained in more detail using reference examples, working examples, and comparative examples, but the present invention is not limited to these actual examples.

Note that all parts and percentages hereinafter are based on weight unless otherwise specified.

First, a commercially available asbestos-containing spraying material was sprayed on concrete to a thickness of 20 mm, the surface of which was troweled, and the material was cured for one month to be used as a base material.

Production Example 1 (Production example of the aqueous polymer latex of the present invention) ■
Polymerizable monomers 2-ethylhexyl acrylate 43 parts Methyl methacrylate 55 Acrylic acid
2〃■ Surfactants Sodium lauryl sulfonate 3 parts (3) Colloidal silica “Snowtex 30” (solid content = 3Q%) 100 parts (a) Ion exchange water 178.3
II■ Polymerization initiators Ammonium persulfate 0.5 parts Sodium hydrogen sulfite 0.2 A surfactant, colloidal silica, and ion-exchanged water were charged into a four-ton flask, and the temperature was raised to 60°C in a nitrogen stream, and then polymerization was started. The mixture of polymerizable monomers was added dropwise over a period of 3 hours, and the reaction temperature at this time was adjusted to a range of 30 to 70°C.

After the dropwise addition was completed, the reaction was continued under stirring while maintaining the same temperature range for 2 hours, and then the mixture was cooled and the pH was adjusted to 8 to 9 with about 14% ammonia water to achieve a solid content of 35%. A stable aqueous polymer latex was obtained.

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

Production Examples 4 to 5 (Production Examples of Water-Dispersible Compositions for Comparison) Aqueous compositions for comparison were prepared in the same manner as Production Example 1, except that the charging ratio of each raw material component was changed as shown in Table 1. A polymer latex was obtained.

Examples 1 to 3 The aqueous polymer latex obtained in Production Examples 1 to 3 was applied to a substrate by air spraying to a solid content of 150 g/rrr, dried for one week at room temperature, and each was applied to an example. 1
~3.

Comparative Examples 1 and 2 The aqueous polymer latex obtained in Production Examples 4 and 5 was applied to a substrate using air spray so that the solid content was 150 g/rrr, dried at room temperature for one week, and each was used as a comparative example. 1
~2.

Comparative Example 3 Ethyl silicate 40 (Colcoat W!4I!, a silicate compound that is a partial hydrolysis of ethyl silicate)
was applied to the base material using air spray to give a solid content of 150 g/rd, and was dried at room temperature for one week.

(Margin below) ni (”-ni (Note) Production examples 4 and 5 are for comparison.

Examples 1 to 3 and Comparative Example 1 prepared as described above
The adhesive strength, impact resistance, and blocking resistance of the treated objects No. 3 to 3 were evaluated. The results are summarized in Table 2.

212! ! (Note) The evaluation criteria are as follows.

Good Qku■〈Δku×Poor The evaluation method is as follows.

(2) Adhesive Strength A 4×4 d attachment was attached to a treated substrate using an epoxy adhesive, and measured using a Kenken type adhesion tester.

(2) Impact Resistance Treatment A 500g iron ball was dropped onto the surface of the substrate from a height of 50C11, and the state of destruction, peeling, and chipping of the treatment agent were visually determined.

■ Anti-blocking treatment The degree of stickiness on the surface of the substrate was judged by feeling with the hand.

As is clear from Table 2, the treatment method of the present invention improves adhesive strength,
It can be seen that it has extremely excellent impact resistance and blocking resistance (staining resistance).

〔Effect of the invention〕

The specific water-based polymer latex used in the treatment of various asbestos-containing objects of the present invention forms a film with excellent adhesion, impact resistance, and blocking resistance (stain resistance) on asbestos-containing objects. can do.

Therefore, by the treatment method of the present invention, it is possible to effectively prevent asbestos from scattering from an asbestos-containing object over a long period of time, and it is also possible to provide an asbestos-containing object with excellent surface properties.

Claims (1)

[Claims] A method for treating asbestos-containing objects, characterized by using a water-dispersible polymer latex obtained by emulsion polymerization of a polymerizable monomer in the presence of colloidal silica.