CS215686B1 - A method of modifying plaster mixtures - Google Patents

Abstract

The invention relates to the field of plasters used for mechanized applied surface treatments of building structures. The invention solves the synergistic rheological effect of the clay mineral montmorillonite in combination with the synthetic polyelectrolyte of sodium salt of carboxymethylcellulose as a modifying additive for plaster mixtures. Montmorillonite as a clay mineral has a platelet-shaped electrically charged particles and behaves as an active ion exchanger and a regulator of the rheological properties of aqueous suspensions and pastes. This activity of its absorbing on its surface molecules of electrolyte with the ability to substitute calcium ion, or magnesium and sodium ion can be used in interaction with the lower salt of carboxymethylcellulose. At optimal concentration of these components in plaster mixtures used for surface treatment of building structures, a synergistic rheological effect is achieved, characterized in addition to improved thixotropy and viscosity, also by reduced wet abrasion resistance and improved adhesion to the substrate, thereby limiting or eliminating the addition of synthetic resins.

Description

The invention solves the synergistic rheological effect of the il mineral mineral montmorillonite in combination with the synthetic polyelectrolyte sodium carboximethylcellulose as a modifying additive for plaster mixtures.

Additions of water-soluble cellulose ethers e.g. methylcelluloses, hydroxyethylcelluloses, or carboximethylcelluloses, which improve the rheology of imine proteins, namely viscosity and thixotropy. They also improve adhesion to the substrate, but worsen wet abrasion resistance. This criterion prescribed by the standard limits their increased content, so the desired adhesion is achieved, for example, by the addition of aqueous dispersions of synthetic resins, most commonly polyvinyl acetate and its copolymers.

The cellulose ethers used are relatively difficult to dissolve in water and must therefore be pre-wetted.

These disadvantages are overcome by the modification mixture according to the invention. Montmorillonite as a clay mineral has a platelet shape of electrically charged particles and acts as an active ion exchanger and regulator of the theological properties of aqueous suspensions and pastes. This activity of absorbing on its surface electrolyte molecules with the ability to substitute the calcium or magnesium ion for sodium ion can be utilized in the interaction with carboxymethylcellulose sodium. By optimally concentrating these components in plaster compositions for surface treatment of building structures, a synergistic rheological effect, characterized in addition to improved thixotropy and viscosity, also results in reduced wet abrasion resistance of plaster, improved adhesion to the substrate, thereby limiting or eliminating the addition of aqueous aqueous dispersions. In addition, the modification mixture dissolves more easily in water, making it usable for plaster even in a dry state without pre-soaking.

Examples of composition by weight:

Small aggregate fraction up to 2 mm 70

Aqueous Diffusion of Synthetic Resin 3

Carboximethylcellulose sodium salt 0,45

Montmorillonit 2

Water 24.55

Small aggregate fraction up to 2 mm

Hydraulic binder 18

Carboximethylcellulose sodium 0.71

Montmorillonite 0,8

Water 20.49

The surface finish of the plaster according to the first composition is after 14 days:

Adhesion to substrate according to CSN 7325577 ..................... 0.55 MPa

Wet abrasion according to surface treatment guidelines, 95 pp., Which represents an improvement of these properties over the mixture without modifiers according to the invention of 30 to 20 percent. Tlxotropy measured by the thickness of the applied plaster layer on the perpendicular wall reaches 2 - 2.5 cm as opposed to 0.5 - 1 cm for the mixture without additives. The surface treatment according to the second example achieves an increase in adhesion to the substrate by 40-50% compared to the composition without modification components. Thixotropy measured by the layer thickness on the rail wall reaches up to 3.5 cm. Without additives only 2 cm.

violet variants of plaster compositions can be prepared ´ with the addition of eg. aqueous solution of alkali silicates, fungicidal, foaming and waterproofing additives, fibrous or extruding materials at an optimum ratio of sodium carboxymethylcellulose with montmorillonite in the range of 0.05-4% over sodium carboxymethylcellulose and 0.5-9% for montmorillonite, * all ingredients.

Claims (1)

40 - 50% higher adhesion to the substrate compared to the non-modifying composition. The thixotropy measured by the thickness of the perpendicular wall reaches up to 3.5 cm. Without added 2 cm. violet variants of plaster compositions can be prepared with the addition of, for example, aqueous solutions of alkali silicates, fungicidal, foaming and waterproofing agents, fibrous materials and leaching materials at an optimum sodium salt ratio of carboxymethylcellulose montmorillonite in the range of 0.05-4% carboxymethylcellulose sodium salt and 0, 5 - 9% for montmorillonite based on weight * in all ingredients. DISCLOSURE OF THE INVENTION A method of modifying plaster compositions consisting of inorganic fillers, synthetic, hydraulic, or combined binders, fungicidal, foaming, waterproofing, fibrous or infused materials by the addition of modifying agents, characterized in that 0.05 to 4 weight percent sodium solicarboximethylcellulose and 0.05 to 9 weight percent montmorillonite.