RU2278086C2 - Dry plaster mix - Google Patents

Abstract

FIELD: building material industry, in particular production dry plaster mix for internal building finishing.

SUBSTANCE: claimed mix contains (mass %): mineral white binding agent, fine milled limestone, methylcellulose, slaked lime, citric acid, and additionally it contains ethylene-vinyl laurate-vinyl chloride terpolymer and vinyl acetate and ethylene copolymer in the next ratio (mass %): mineral white binding agent 70-82; fine milled limestone 15-25; slaked lime 3-5 and above 100 % of mixture of three components mentioned above: methylcellulose 0.2-0.4; citric acid 0.075-0.09; ethylene-vinyl laurate-vinyl chloride terpolymer 0.75-1.0; and vinyl acetate and ethylene copolymer 0.3-0.5.

EFFECT: increased strength characteristics, water-retaining capacity, adhesion strength of obtained plasters.

1 ex

Description

The invention relates to the building materials industry and can be used in the production of dry plaster mixes for interior decoration of buildings for various purposes.

A known stucco mixture comprising β-calcium sulfate hemihydrate (gypsum binder), water-soluble methyl cellulose, a surfactant based on sodium alkyl sulfanate, finely ground limestone, quicklime and tartaric acid (USSR copyright certificate No. 1652323, class C 04 B 28/14 , 05/30/91. Bull. No. 20).

The disadvantage of the stucco mixture is the low strength characteristics due to the insufficient amount of gypsum binder. An increased amount of filler may result in a reduced adhesive bond to the surface being trimmed.

The closest analogue to the purpose and combination of essential features is a stucco mixture containing gypsum binder, finely ground limestone, slaked lime, methyl cellulose and citric acid (GB 1258078 A, publ. 12.22.1971, 3 pp. - prototype).

The disadvantage of the prototype is the lack of polymer additives that increase the strength characteristics, adhesive strength and water resistance of the plaster mixture.

The technical task of the invention is to increase the strength characteristics, water-holding ability, adhesive strength and water resistance while maintaining the viability of the stucco mortar.

The problem is solved in that the dry stucco mixture, including gypsum binder, finely ground limestone, methyl cellulose, slaked lime, citric acid, contains Vinnapas RI 551 Z - a copolymer of ethylene, vinyl laurate and vinyl chloride and Vinnapas RE 5 10 Z - a copolymer of vinyl acetate and ethyl acetate the ratio of components, wt.%:

Gypsum binder 70-82 Fine limestone 15-25 Slaked lime 3-5 and in excess of 100% by weight of the mixture of the above three components cellulose 0.2-0.4 Lemon acid 0,075-0,09 Winnapas RI 551 Z 0.75-1.0 Winnapas RE 510 Z 0.3-0.5

To prepare a dry plaster mix use:

Gypsum binder grade G-5 - G-7 (GOST 125-79 *); finely ground limestone as a filler to reduce the consumption of gypsum binder and to increase the density of the stucco mixture (particle size 100 μm); methylcellulose grade MC-S (TU 2231-107-05742755-96) to increase water retention capacity; slaked lime (GOST 9179-77 *) to increase the water-holding ability and plasticity of the mixture; citric acid to increase the viability of the stucco mixture (GOST 908-79); Vinnapas polymer RI 551 Z, which increases the water resistance of the finish coating, is a water-dispersible powder, a triple copolymer of ethylene, vinyl laurate and vinyl chloride; Vinnapas polymer RE 510 Z, which improves the adhesion of one layer to another, is a water-redispersible powder based on a copolymer of vinyl acetate and ethylene with good resistance to saponification.

Each component of the dry plaster mix and their interaction with each other determine the receipt of positive results. The initial semi-aquatic gypsum CaSO ₄ · 0.5H ₂ O, when mixed with water, passes into the two-water gypsum CaSO ₄ · 2H ₂ O. The mortar crystallizes. With the introduction of slaked lime into the plaster composition, technological properties such as water-holding ability, plasticity of the mixture improve, and adhesive strength increases.

Methyl cellulose swells when dissolved in water. The ability of methylcellulose to induce a thickening effect is directly related to the rheological properties, and in particular to the structural viscosity of this product. Due to its structural viscosity, methylcellulose improves some characteristics of the stucco mortar, such as, for example, ductility, stability, low stickiness with respect to the working tool.

Introduction to the mixture of citric acid provides a more complete passage of the curing reaction of all components, reduces the water-gypsum ratio V / G, increases the viability of the composition, water resistance and crack resistance. Depending on the required viability of the stucco mixture, the necessary amount of citric acid 0.075 - 0.09% in excess of 100% by weight of the mixture of gypsum binder, finely ground limestone and slaked lime was experimentally selected. The viability of the composition was 40 - 100 minutes

The introduction of Vinnapas RI 551 Z polymer provides a significant reduction in water absorption. The advantage of Vinnapas dispersion powders with a hydrophobic effect is that they improve the adhesion of plasters by acting as a polymer binder. They have a high level of elasticity and low viscosity. The amount of Vinnapas polymer RI 551 Z was selected based on the highest strength characteristics and the lowest water absorption by weight. The Vinnapas polymer RI 551 Z was introduced in an amount of 0.3-1.5% in excess of 100% by weight of a mixture of gypsum binder, finely ground limestone and slaked lime. According to the test results, the optimal amount of Vinnapas RI 551 Z 0.75 - 1.0% polymer was selected, at which the flexural strength was 1.63-1.86 MPa, the compressive strength was 4.8-5.44 MPa, and water absorption by weight 36.15-36.55%, softening coefficient - 0.81-0.95.

Vinnapas RE 510 Z polymer, which improves the adhesion of one layer to another, is a water-redispersible powder. The amount of Vinnapas RE 510 Z polymer was selected based on the highest compressive, bending, and tear strengths. Vinnapas polymer RE 510 Z was introduced in an amount of 0.2-0.5% in excess of 100% by weight of a mixture of gypsum binder, finely ground limestone and slaked lime. According to the test results, the optimal amount of the introduced Vinnapas RE 510 Z polymer was 0.3-0.5%, while the bending strength was 4.5-4.87 MPa, the compressive strength was 9.74-10.72 MPa, and the strength on separation - 0.85-1.25 MPa.

The invention is carried out as follows: a dry gypsum plaster mixture is prepared in a paddle mixer, where all metered components are loaded. The components of the mixture are introduced into the mixer in the following order: gypsum binder, finely ground limestone, slaked lime, methyl cellulose, citric acid, Vinnapas polymer RI 551 Z, Vinnapas polymer RE 510 Z. Mixer operating time 5-7 min. Mixing the mixture is carried out immediately before the plastering. The composition is kept for 5 minutes to better dissolve the chemical additives and mix again.

Example.

To assess the suitability of the proposed mixture, a solution is prepared from a dry mixture containing (wt.%): Gypsum binder - 70, finely ground limestone - 25, slaked lime - 5 and over 100% methyl cellulose - 0.4, citric acid - 0.09, Vinnapas RI 551 Z - 1.0, Vinnapas RE 510 Z - 0.5 and from the dry mix containing gypsum binder - 82, finely ground limestone - 15, slaked lime - 3 and over 100% methyl cellulose - 0.2, citric acid - 0.075 Winnapas RI 551 Z - 0.75; Winnapas RE 510 Z - 0.3. In all compositions of the solutions take W / T = 0.5. According to the results of experiments within the specified limits, the following characteristics were obtained: compressive strength - 13.31-19.81 MPa (4.2-4.8 MPa - prototype); bending strength 5.22-7.13 MPa; water retention capacity - 95.24-97.94%; tensile strength - 0.85-1.25 MPa; viability - 40-100 minutes.

With an increase in the content of finely ground limestone in the mixture from 25 to 30%, a sharp decrease in strength characteristics is observed, it is also impractical to introduce more than 5% slaked lime into the mixture, since this does not lead to an increase in water retention and adhesion strength. With the introduction of more than 0.4% methylcellulose into the mixture, the water holding capacity and strength characteristics do not increase.

The present invention improves the strength characteristics by an average of 80%; water retention ability, adhesive strength and maintain the viability of plaster mortars.

Storage of the obtained dry stucco mixture must be carried out in sealed containers. The implementation period is up to 6 months.

Claims (1)

Dry plaster mix, including gypsum binder, finely ground limestone, methylcellulose, hydrated lime, citric acid, characterized in that it additionally contains Vinnapas RI 551 Z-copolymer of ethylene, vinyl laurate and vinyl chloride and Vinnapas RE 510 Z-copolymer of vinyl acetate and ethylene with the following ratio of vinyl acetate and ethylene components, wt.%: Gypsum binder 70-82 Fine limestone 15-25 Slaked lime 3-5 and in excess of 100% by weight of the mixture of the above three components Cellulose 0.2-0.4 Lemon acid 0,075-0,09 Winnapas RI 551 Z 0.75-1.0 Winnapas RE 510 Z 0.3-0.5