RU2194065C2 - Powder composite for cover - Google Patents

Abstract

FIELD: paint and varnish materials. SUBSTANCE: powder composite comprises polyurethane as a binding agent obtained on the base of toluylenediisocyanate and propylene oxide simple oligoether (Laprols of grades 373, 503B, 594, 1052, 5003) taken in the ratio (1.0-1.0) : (1.0-1.2) (in equivalent ratios) and it comprises titanium dioxide, silicon dioxide, dolomite, sodium polyphosphate, OP-7, polyvinyl alcohol, acremos 402 and stearic acid heptyl ester additionally. Powder form of "dry" dye ensures to prepare the required in this moment amount of dye. Also, this dye shows very useful properties since it can be stored as powder and shows rather transportable and cold-resistant properties. Dye is not subjected for spoil in dry form and ready for using after mixing with water immediately. Dye with said properties does not contain any preserving agents and evaporating solvents and therefore it does not pollute environment. Proposed powder composite is designated for preparing protective-decorating covers by metallic backings and can be used in building industry and in homes, for internal staining constructions and buildings by brick, concrete, plastered, wood and other porous surfaces. EFFECT: improved quality and properties of composite. 2 tbl

Description

 The invention relates to paints and varnishes, in particular, to redispersible powder compositions intended for the production of protective and decorative coatings on non-metallic substrates, as well as for the internal painting of buildings and structures on brick, concrete, plastered, wooden and other porous surfaces.

A known powder composition comprising a thermoplastic polyester and a means for improving filling; as a thermoplastic polyester contains a copolyester of 1,4-butanediol or a mixture thereof with aliphatic C ₂ -C ₆ diols and tere- and / or isophthalic acid or a mixture thereof with C ₆ -C ₁₀ aliphatic dicarboxylic acids having a melting point of 150-200 ^o C, wt.% (Germany, author certificate 605548, class C 09 D 5/00, 1978):
Copolyester - 95 - 99.9
Means for improving filling - 0.1 - 5
However, this composition is not redispersible and is used only in powder form, and coatings can be formed only at high temperatures (180-200 ^o C).

Known for the closest in technical essence and selected for the prototype powder paint containing a binder polyester resin, with the following components, wt.% (USSR, author certificate No. 734238, class 09 D 5/03, 1980):
Saturated Polyester Resin - 60 - 80
Thermoset Acrylic Copolymer - 0.4 - 6.0
Hardener - 3 - 10
Surfactant - 0.2 - 3.0
Pigments and Fillers - Else
However, this paint has a number of disadvantages:
- you need a sufficiently high temperature (about 200 ^o C) to form a coating;
- requires special expensive equipment for coating;
- dusting occurs during coating, which worsens the environment in the workshop and adversely affects the health of workers.

 Also, a paint of this nature does not have the ability to redisperse, which excludes the possibility of its use as a dry mixture in construction.

The objective of the invention is to provide a dry paint capable of redispersible in water immediately before use (i.e., redispersible powder paint), coatings based on which can be formed at low temperatures (<15 ^o C). The term “redispersible” emphasizes the special and important property of a synthetic resin: the ability of a dried dispersion to re-disperse in water.

In this case:
- there is no need to transport water (transportation and storage are cheaper);
- simple and cheaper packaging - paper bags (simplifies the disposal of containers);
- storage and transportation are possible even in extremely difficult climatic conditions (for example, in cold weather) without compromising the quality of the paint;
- ease of preparation of paint on the construction site by mixing the dry mixture in water (the ability to prepare the paint in the quantity necessary for work);
- no special equipment for application is required - paint is applied to the surface with rollers or a brush;
- due to the low temperature of formation of coatings, such paints are applicable for various construction works, for example, for decorating walls and ceilings on brick, concrete, plaster, wood and other porous surfaces (Lutz G. Powder polymers for the modification of dry building paints. LKM and their application, 1997, 2, p. 26-27).

The object of the invention is achieved in that the powder coating composition contains a binder, which is used as a polyurethane, obtained on the basis of toluene diisocyanate and propylene oxide oligoesters of grades 373, 503B, 594, 1052, 5003 (laprols are oligoesters obtained by anionic polymerization of propylene oxide), taken in the ratio of 1.0: 1.0 to 1.0: 1.2 (in equivalents); as a pigment contains titanium dioxide; as filler, silicon dioxide and dolomite (CaCO ₃ • MgCO ₃ ); as a surfactant, sodium polyphosphate (dispersant), OP-7 (manufacturer's trademark; represents polyoxyethylene ether of alkyl phenol) (emulsifier, wetting agent), polyvinyl alcohol (stabilizer), acramos 402 (manufacturer's trademark; is a butyl acrylate copolymer, methacrylic acid with glycidyl methacrylate) (thickener), stearic acid heptyl ester (stabilizer) in the following ratio, wt.%:
Polyurethane - 15 - 25
Titanium Dioxide - 14.06 - 23.44
Silicon Dioxide - 5.63 - 9.37
Dolomite - 35.94 - 60.94
Sodium Polyphosphate - 0.38 - 0.63
OP-7 - 1.5 - 2.5
Polyvinyl alcohol - 0.19 - 0.31
Akramos 402 - 1.5 - 2.5
Stearic acid heptyl ester - 0.19 - 0.31
Polyurethane is synthesized as follows. In a four-necked flask equipped with a thermometer, stirrer and reflux condenser, a 50% solution of laprol in toluene is charged. They include a stirrer and heating. From a dropping funnel, a 50% solution of toluene diisocyanate in toluene is gradually added dropwise into a four-necked flask with a solution of laprol. The synthesis is carried out at a temperature of 60 ^o To the degree of completion of the reaction, calculated according to the equation of Carozers, which is estimated by the isocyanate number. Upon reaching the required degree of completion, a solution of a secondary amine in acetone is poured into the obtained polymer to block isocyanate groups. Next, the reaction mixture is washed repeatedly with water, after which the water-toluene mixture is distilled off. The characteristics of the film-forming are shown in table 1.

 The preparation of "dry" paint is illustrated by the following example.

 Example 1. The resulting solution formed during the synthesis of the oligomer is checked for the content of the basic substance (dry residue) and diluted, if necessary, to a 30% concentration.

The disolver is loaded in wt.%:
Polyurethane - 20
Titanium dioxide - 18.75
Silicon Dioxide - 7.5
Dolomite - 48.75
Sodium Polyphosphate - 0.50
OP-7 - 2.0
Polyvinyl alcohol - 0.25
Akramos 402 - 2.0
Stearic acid heptyl ester - 0.25
Dispersion is carried out to achieve a degree of dispersion of 38 - 40 microns, which is controlled by the wedge method. After dispersion, the solvent is removed from the resulting product and the dry mixture is crushed.

 The resulting powder is the desired form of "dry" paint.

 A ready-to-use paint material is obtained by adding water to the powder in the ratio powder: water 1: 1 - 3: 4 (by weight) and thoroughly mixing it first for 60 s, and then after a ten-minute break for another 5 minutes.

 The material was applied (with a brush, roller, paint sprayer) to glass, wood, concrete and plastered substrates. After curing, the resulting coatings were evaluated by appearance, adhesion, and washability.

 Examples 2-6 are similar to example 1. The test results of samples of compositions of various compositions are shown in table 2.

 As can be seen from the above examples, coatings obtained on the basis of the proposed compositions have satisfactory adhesion and hardness compared with the compositions obtained by the prototype.

 The powder form of "dry" paint makes it possible to prepare such an amount as is required at the moment. In addition, this paint is very practical due to the fact that in powder form it freezes and frost does not affect the quality of the paint at all. When dry, it does not deteriorate and is immediately ready for use after mixing with water. Also, the paint does not pollute the environment, since it does not contain any preservatives or toxic solvents.

 In addition to the positive qualities of the paint listed above, it is necessary to mention its practical packaging (paper bags), as water is added only before use, which is very convenient and beneficial during transportation.

Claims (1)

A powder coating composition comprising a binder, pigment, filler, surfactant, characterized in that the composition contains as a binder a polyurethane obtained on the basis of toluene diisocyanate and propylene oxide oligoester, taken in a ratio of 1.0: 1.0 - 1, 0: 1.2, as filler - silicon dioxide and dolomite, as a pigment - titanium dioxide, as a surfactant - sodium polyphosphate, OP-7 - polyoxyethylene ether of alkyl phenol, polyvinyl alcohol, acramos 402 - butylac copolymer Rilate, methacrylic acid with glycidyl methacrylate, heptyl ester of stearic acid in the following ratio, wt. %:
Polyurethane - 15 - 25
Titanium Dioxide - 14.06 - 23.44
Silicon Dioxide - 5.63 - 9.37
Dolomite - 35.94 - 60.94
Sodium Polyphosphate - 0.38 - 0.63
OP-7 - 1.5 - 2.5
Polyvinyl alcohol - 0.19 - 0.31
Akramos 402 - 1.5 - 2.5
Stearic acid heptyl ester - 0.19 - 0.31

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