RU2460739C1 - Composition for application onto metal and concrete surfaces - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention represents an emulsion, in which oligomers with terminal isocyanate groups are a dispersion medium, and a disperse phase is a solution or a dispersion produced as a result of mixing a lime solution with calcium hydroxide content of 10-70 wt % with glycerine in the amount of 1-250 wt parts per 100 wt parts of calcium hydroxide, besides, the disperse phase content in the composition makes 1-55 wt %.

EFFECT: development of a cheap and easy to apply composition, coatings from which have high adhesion to moist metal or concrete surfaces, have proper adhesion to concrete applied onto them, are hardened with specified speed at temperature from zero and above, inhibit processes of metal corrosion and have low elasticity module.

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Description

The invention relates to compositions based on isocyanates used for applying to metal or concrete surfaces, especially for the production of polymer coatings on the degraded surfaces of underground pipelines during their rehabilitation, as well as as an inhibitory primer when painting metals and as a sealant.

Often, metal and concrete surfaces, on which it is necessary to apply a polymer coating, are not in stationary controlled factory conditions, but in conditions when they have been exposed to the environment for a long time. In the latter case, these surfaces have defects and impurities and, as a rule, are wet, therefore, the compositions serving for applying to such surfaces are subject to increased requirements: they must have sufficient adhesion even to such defective wet surfaces.

In addition, if the polymer coating obtained by applying the composition is used as an intermediate layer for gluing freshly applied concrete mixture to old concrete or metal, it should provide high adhesion to the applied concrete, usually shotcrete.

Known polymerizable composition according to patent RU 2259378, which per 100 wt.% Unsaturated oligoester and a crosslinking agent contains 1-50 wt.% Semi-butadiene diisocyanate. The curing of this composition after application is carried out using ultraviolet light.

The composition for producing a polyurethane coating according to US Pat. No. 6,291,625 contains a polyol composition and a polyisocyanate. The polyol composition was prepared by mixing a C ₁₂ -C ₂₅ triglyceride hydroxy-substituted fatty acid and calcium hydroxide to hydrolyze the triglyceride and form free fatty acid and glycerol, followed by saponification of the fatty acid to form a fatty acid salt. Calcium hydroxide is taken in an amount of at least 0.1 mol per mole of triglyceride.

The composition according to EP 0145269 is a two-component system. The first component contains a water-soluble or dispersible alkali that reacts with carbon dioxide, an emulsifying agent and at least one polyol having primary hydroxyl groups. The second component contains a prepolymer with terminal isocyanate groups dissolved in an organic solvent, an additional polyisocyanate and a thoroughly dried filler.

None of the described compositions satisfactorily satisfy the above requirements. In addition, none of these compositions provides a polymer coating to which the shotcrete applied to it can firmly adhere.

The basis of the invention is the task to develop a composition that provides high adhesion of the resulting polymer coating with wet metal and concrete surfaces, which has high adhesion to the concrete applied to the polymer coating and which is inexpensive and easy to use.

In the composition for applying to metal or concrete surfaces containing oligomers with terminal isocyanate groups and calcium hydroxide, the problem is solved in that it is an emulsion in which oligomers with terminal isocyanate groups are a dispersion medium, and the dispersed phase is a solution or dispersion, obtained by mixing a lime solution with a calcium hydroxide content of 10-70 wt.%, and glycerol in an amount of 1-250 wt. parts per 100 wt. parts of calcium hydroxide, and soda zhanie in the disperse phase composition is 1-55 wt.%.

Preferably, as oligomers with terminal isocyanate groups, it contains diisocyanates selected from the group consisting of polybutadiene diisocyanates and macrodiisocyanates obtained by reacting polyethers with toluene diisocyanate, hexamethylene diisocyanate or diphenylmethanediisocyanate.

As oligomers with terminal isocyanate groups, the composition may contain polypropylene triol-based triisocyanates.

The polymer composition is an emulsion in which the dispersion medium is oligomers with terminal isocyanate groups — diisocyanates (DIC), and the dispersed phase is a solution or dispersion of calcium hydroxide in water — a lime solution (IR) with the addition of glycerol. Two molecules of glycerol in the secondary hydroxyl groups can react with one molecule of calcium hydroxide with the formation of calcium glycerate - disubstituted calcium hydroxide. However, in accordance with the invention, the mass ratio of calcium hydroxide and glycerol introduced into TS is selected so that not all calcium hydroxide is converted to calcium glycerate. Due to this, along with a solution or dispersion of calcium glycerate in water, a product of the interaction of one glycerol molecule and one calcium hydroxide molecule - monosubstituted calcium hydroxide (GGK) is present in IR.

It is clear to the skilled person that instead of calcium hydroxide, in some cases, hydroxides of other alkaline earth metals may be used.

Krasol LBD prepolymer (Czech Republic) —polybutadiene diisocyanate with a 3.2% NCO content (PBDIC) or macrodiisocyanates (prepolymers) obtained by reacting polyethers such as polypropylene glycols (PPG) or polytetramethylene glycols (PTANM) TDI), hexamethylene diisocyanate (HMDI) or diphenylmethanediisocyanate (DFMDI). Triisocyanates based on, for example, polypropylene triols (PPT) can also be used as oligomers. The polymers obtained on the basis of these products are distinguished by elasticity, high strength and alkali resistance. The elasticity and strength of polymers are easily controlled by changing the type of polyisocyanate and its molecular weight. In addition, well-known substances used in the preparation of polyurethanes can be introduced into the composition: plasticizers, monomeric diisocyanates, glycols, triodes, catalysts, pigments, fillers, flame retardants, etc.

The curing of the DIC occurs mainly due to the interaction of isocyanate groups with water at the interface, the carbon dioxide released during this interaction is quickly absorbed by water and calcium hydroxide in it, which eliminates the possibility of foaming of the composition. The rate of interaction of isocyanate groups with water in an alkaline medium is relatively high, which complicates the practical use of the composition in hard to reach places, for example, when applied to the inner surface of pipelines. Reducing the speed by reducing the concentration in the composition of TS is not desirable, as this can lead to foaming of the composition. A decrease in the rate of such interaction and, consequently, an increase in the viability of the composition is easily achieved by introducing substances that do not react with isocyanate groups and concentrate at the interface. As such substances, surfactants, bitumens or their solutions, polymer solutions, chemical waste, etc. can be used.

Isocyanate groups also react with the primary hydroxyl groups of the HHC. The molecules of the resulting product have a pronounced diphilicity, which explains the high adhesion of the polymer to wet metal and wet concrete. In addition, it can be assumed that monosubstituted calcium hydroxide may participate in the hydration of the concrete mixture, providing high adhesion to it of the resulting polymer.

The anticorrosive activity of the composition is determined by the presence in it of a solution of calcium hydroxide and GGK, while the solubility in water of GGK is several times higher than calcium hydroxide, which significantly increases the protective properties of the coating.

The composition has a low cost, since it uses water as a diluent.

The table shows examples of compositions that have been tested when applied to a metal or concrete surface under various conditions. Compositions were prepared immediately prior to testing by mixing the ingredients. Glycerin was injected into a lime solution with a calcium hydroxide content of 40 wt.%, The rest was water. The oligomer: TS + glycerin ratio in the composition was 60:40. For adhesive tests, a composition 1 mm thick was applied to the surface of a metal or concrete plate, after 1 hour, a concrete mixture 10 mm thick was applied to the composition. The mixture was prepared from Portland cement ПЦ 11 / Б-Ш-400 cement, sand with a particle size modulus of 1.5, the cement-sand ratio was 1: 3, the water-cement ratio was 0.5, the concrete mixture solidified at room temperature. A month after applying the mixture to it, a metal fungus was glued with epoxy glue and it was torn off using a PosiTest, DeFelsko adhesive meter.

No. p / p The components of the synthesis of DIC The number of glycerol in IR,% Plate material Adhesive Strength, MPa Nature of destruction one TDI - Steel 0.2 Adhesive PPG-502 dry polymer - shotcrete 2 TDI - Steel 0.2 Adhesive PPG-502 wet steel polymer 3 TDI - Concrete 0.2 Adhesive PPG-502 wet polymer - shotcrete four TDI fifteen Steel 2,8 Cohesive PPG-502 wet shotcrete 5 TDI - Steel 0.1 Adhesive PPG-1002 dry polymer - shotcrete 6 TDI - Steel 0.1 Adhesive PPG-1002 wet steel - polymer 7 TDI 0.1 Steel 0.3 Adhesive PPG-1002 wet steel - polymer 8 TDI 0.5 Steel 0.9 Adhesive PPG-1002 wet polymer - shotcrete 9 TDI one Steel 1,6 Adhesive PPG-1002 wet polymer - shotcrete 10 TDI 5 Steel 2.6 Cohesive PPG-1002 wet shotcrete eleven TDI twenty Steel 2.7 Cohesive PPG-1002 wet shotcrete 12 TDI fifty Steel 2.7 Cohesive PPG-1002 wet shotcrete 13 TDI 70 Steel 1,6 Adhesive PPG-1002 wet polymer - shotcrete fourteen TDI 80 Steel 0.7 Adhesive PPG-1002 wet polymer - steel fifteen TDI twenty Concrete 2.6 Cohesive PPG-1002 wet shotcrete 16 TDI fifteen Steel 2,3 Cohesive BCP-2002 wet by polymer 17 TDI fifteen Steel 2,8 Cohesive PTMG-902 wet shotcrete eighteen PBDIC fifteen Steel 2.7 Cohesive wet by polymer 19 PBDITS-90% fifteen Steel 2.9 Cohesive + TDI-10% wet on shotcrete twenty PBDIC fifteen Concrete 2.6 Cohesive wet by polymer 21 PBDITS-90% - Concrete 0.2 Adhesive + TDI-10% wet polymer concrete 22 DFMDI fifteen Steel 2.9 Cohesive PPG-1002 wet shotcrete 23 GMDI fifteen Steel 2.7 Cohesive PPG-502 wet shotcrete 24 TDI 5 Steel 1,1 Cohesive PPT-5003 wet by polymer

The number after the name of the polyester denotes the molecular weight of the polyester, the last figure is its functionality.

As can be seen from the table, compositions that do not contain glycerol cannot be used for sanitation of pipelines using concrete mix due to the low adhesion of the composition to wet metal, wet concrete and shotcrete. In composition No. 13, when the content of glycerol in 70% of IR is almost completely consumed for the formation of calcium glycerate, and starting from this concentration, a sharp decrease in the adhesive strength of the polymer to both wet metal and concrete mix is observed. As can be seen from the table, the recommended glycerol content in TS should be in the range of 1-70%. Thus, the main factor determining the adhesion strength is the presence of HHC in the composition; the type of oligomer is practically irrelevant.

The maximum value in the IR composition, above which phase inversion occurs, is in the range of 45-55%. The minimum value below which foaming of a coating 1 mm thick at room temperature can occur is for a composition based on TDI and PPG-502 35-40%, TDI and PPG-1002 30-35%, DFMDI-PTMG-902 - 15-20 %, PBDITs - 1-5%, GMDI and PPG-1002 10-15%.

The water content in IR can vary from 10 to 99%, at extreme values the absorption rate of carbon dioxide released during the interaction of isocyanate groups with water is small, the recommended values are 30-90%.

The thickness of the polymer coating on the inner surface of the pipeline depends on the state of the metal surface, the diameter of the pipeline and the possible magnitude of the deformation of the pipeline due to soil movements and lies in the range of 0.1-10 mm Within these limits, the physicomechanical properties of the coating practically do not change. Changes in the curing temperature of the composition in the range of 0-40 ° C also do not lead to significant changes in the properties of the polymer.

The curing time of the composition depends on the composition of the oligomer and temperature. So, at 20 ° C the curing time of the compositions is: TDI and PPG-502 20-30 min, TDI and PPG-1002 30-40 min, DFMDI-PTMG 25-35 min, PBDIC 3-4 hours, GMDI and PPG 1- 2 hours. A change in the curing temperature of the composition by 10 ° C leads to a change in the curing time of approximately 2 times. After curing the composition, its ability to form a strong adhesive bond with shotcrete remains for 1-3 days.

The cheapest and technologically convenient composition is based on TDI and PPG-1002, however, the high curing rate makes its practical application difficult. Due to the fact that the curing reaction of the composition proceeds at the polymer-water interface, the use of surfactants that are concentrated at the interfacial boundary sharply reduces the curing rate. As surfactants, it is recommended to use well-known anionic (alkylaryl ethyl sulfates, alkyl cyclohexyl ethyl sulfates, naphthalene sulfonates, salts of perforated carboxylic acids, etc.) or nonionic substances (for example, block copolymers), which not only reduce the curing rate of the composition, but also provide a uniform, non-crosslinking structure. The introduction of water repellents, for example, solutions of bitumen or paraffins in hydrocarbons, also reduces the cure rate of the composition. Thus, the introduction of a 10% one percent solution of bitumen in xylene into the composition reduces its cure rate by 3-4 times, and perfluorinated carboxylic acids by 4-5 times.

Thus, coatings obtained using the composition according to the invention have the following properties:

1. Have good adhesion to metal or concrete, including wet surfaces.

2. Have good adhesion to the sprayed concrete applied to them.

3. Cure at a given speed at temperatures from zero and above.

4. Inhibit metal corrosion processes.

5. Have a low modulus of elasticity.

Claims (3)

1. Composition for applying to metal or concrete surfaces containing oligomers with terminal isocyanate groups and calcium hydroxide, characterized in that it is an emulsion in which oligomers with terminal isocyanate groups are a dispersion medium, and the dispersed phase is a solution or dispersion obtained as a result of mixing a lime solution with a calcium hydroxide content of 10-70 wt.% with glycerin in an amount of 1-250 wt.h. per 100 parts by weight calcium hydroxide, and the content in the composition of the dispersed phase is 1-55 wt.%. 2. The composition according to claim 1, characterized in that, as oligomers with terminal isocyanate groups, it contains diisocyanates selected from the group consisting of polybutadiene diisocyanates and macrodiisocyanates obtained by the interaction of polyethers with toluene diisocyanate, hexamethylene diisocyanate or diphenylmethanide. 3. The composition according to claim 1, characterized in that as oligomers with terminal isocyanate groups it contains triisocyanates based on polypropylene triols.