CS206098B1 - Method of hydrophobic treatment of the mortars,plasters and coloured lime coatings - Google Patents

Description

The invention relates to a method of hydrophobic treatment of mortars, plasters and color-lime coatings to increase their durability and aesthetic appearance.

The durability of the plasters is greatly reduced by the ingress of rainwater and groundwater by building materials. Another significant reduction in the service life of plasters and paints, which are prepared on the basis of lime binders, is due to the action of gaseous and solid fumes and weather conditions.

Various methods are used to increase the resistance of plasters. The treatment can be carried out, for example, by the addition of water glass, which, however, also causes an increase in the ductile resistance of the plaster during the passage of water vapor and the introduction of alkali into the building material, which is both harmful. The addition of fluorosilicates is also used for this purpose, which works in a similar manner, but only alkali is less, since the chemical reactions taking place between the fluorosilicate and the building material produce insoluble calcium fluoride and magnesium hydroxide. As a further treatment, the addition of an alkaline soap solution is used, from which calcium-aluminum compounds are formed in the plaster mixture. Among the modern formulations, pragosilicon compounds have been used for this purpose, in the form of coatings extending only to the surface layer, which is different in physical properties from most of the plaster material. The patent literature describes a process for the preparation of internally hydrophobized plasters, which are impregnated throughout the mass by the relatively small addition of reactive organosilicon ester, which can therefore

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20B - only slightly influence the diffusion resistance of the plaster. Composition t.zv. The DVH of the composition is adapted so that the chemical reactions taking place in the plasters result in a bond between the organosilicon compound and the solid phase formed by silicates. However, the main disadvantage of this method of treating the plaster composition is the presence of only one organic group directly bound to the silicon.

When this single organic group, which is responsible for the hydrophobic properties of the impregnated material, is degraded, for example, by UV radiation or the alkalinity of the material, the hydrophobicity of the material ceases.

SUMMARY OF THE INVENTION The present invention relates to a process for the hydrophobic treatment of plasters by the addition of an iftalic amount, for example 1 to 10%, of highly hydrophobic organosilicon compounds of the general formula (RHSiO)

R - alkyl, aryl., Aralkyl of up to 0 ₂ θ m - 1 to 40 and n - is greater than 2 m, at most 300, in intimate mixture and maturing over a period of 10-30 hours at 0 ° C to 30 ° C , with the following application as usual.

Due to the alkaline environment, which is always in the wet plaster mixture, at the time of decomposition hydrogen atoms from the organosilicon molecule cleave and chemical siloxane bond with silicates from building material and calcium ions to form alkali silicates, which achieves exceptional stability of hydrophobic organosilicon substances hydrophobic properties. Exceptional stability stems not only from the formation of a chemical bond, but also from the fact that two methyl groups are attached to most silicon atoms, so that the polymer's resistance to both UV and alkaline conditions is significantly higher than that of organosilicon polymers containing only one organic group on silicon. .

Since the organosilicon compound of formula (RHSiO) _m (R ₂ SiO) _n may be incorporated into the plaster mixture in the form of a water emulsion eliminates hydrophobic additive of the present invention and disadvantages of conventional organosilicon hydrophobing agents which are introduced in a solution of organic solvents . This means, in addition to removing flammable and harmful solvents, a substantial reduction in the cost of the hydrophobizing agent.

Examples of carrying out the process according to the invention are given below.

Example 1

The plaster mixture is prepared from 66.6 l of river sand with a grain size of up to 4 mm, 33.3 l of dredged sand, 27 l of lime hydrate, 4.01 l of Permanent cement of 325, 32 l of mixing water and 2.0 l of aqueous tricosamethylcyclotrididekasiloxane emulsion. composition (CH ₃ HSiO) ₃ / (CH ₃ ) ₂ SiO / _lo . The plaster is applied to the brick wall using traditional façade technology using common façade tools and work tools. After the plaster has dried and conventional carbonization processes have been completed, the plaster exhibits permanently hydrophobic properties. Compared to other additives for achieving hydrophobic properties, eg sodium methylsilanolate, where the hydrophobicity of the plaster is lost within about 3 years, the effect of the described treatment is guaranteed for at least 15 years.

Example 2 ^{208 088} stucco is prepared from 25 l fine stucco sand of 0 to 1 mm grain size, 10 l lime slurry of 12 and 0.6 l aqueous emulsion of tetraethyltetracontacycloXyldocosasiloxane composition / (UHg) ₂ HSiO / ₂ · / ( ^C 6 ^H h) 2 ^Si ° / 20 O 'stucco plaster is applied by conventional facade technology to a still wet core plaster prepared according to Example 1. The duration of hydrophobicity of this stucco plaster is similar to that of Example 1.

Claims (1)

SUBJECT OF THE INVENTION A method of hydrophobic treatment of mortars, renders and colored lime paints for enhancing their lifetime and improving the aesthetic appearance is characterized by the addition of 0.1-10% by volume of organosilicon highly hydrophobic substances of the general formula (RHSiO) (R _o SiO) ) m 2 η i where it represents: R - alkyl, aryl, aralkyl with up to C ₂₀ , m - 1 to 40 and n - number greater than 2m, maximum 300, mix thoroughly and allow to stand for 10 to 30 hours at 0 ° C to 30 ° C, whereupon it is applied in a conventional manner.