SU1758054A1 - Coating compound - Google Patents

Abstract

Use: protective coating. SUMMARY OF THE INVENTION: the composition contains epoxy resin dianovu 10-12%, polystyrene 8-10%, thioneaphene formaldehyde resin as a by-product naphthalene formaldehyde cleaning product 10-13%, isomethyl tetrahydrophthalic anhydride 2-5%, toluene the rest. Polystyrene is mixed with solvent until completely dissolved at room temperature. With stirring, epoxy resin and hardener are added. Toluene is added to a viscosity of 30-40 seconds. Coating characteristics; adhesion 1 point, flexural strength 1 mm, impact strength 40-50 kg / cm2, corrosion rate 0.00235 mm / year. 5 tab

Description

The invention relates to compositions for the protection of metal products and structures against atmospheric corrosion with the help of chemical resistant protective compositions and can be used in chemical industries.

Known protective compositions based on epoxy resins containing plasticizers, modifiers, hardeners and pigments.

The disadvantages of these compositions include the use to cure toxic hardeners (amines) and the shortage of these materials.

A known epoxy composition for the protection of metal products, including a diacano resin, an anhydride hardener, a tertiary amine, and a flame retardant, used as bis- (2,3-dibromopropyloxymethyl) phosphonic acid

The disadvantage of this composition is that the curing of this composition occurs at elevated temperatures (70 ° C) for 3-4 hours. In addition, the coatings obtained on the basis of this composition do not possess the high physicomechanical properties required for paint coatings (low adhesion and fragility).

The closest in technical essence and the achieved result is a composition for protective coatings prepared on the basis of ED-20 epoxy resin, polystyrene, toluene, talc and hardener with the following content of components, wt.% Xj SL 00

about with

-N

resin

olyamine

20.0

5.0

10.0

63.0

2.0

The disadvantage of this composition is fragility, poor resistance in an atmosphere containing moisture, hydrogen cyanide, hydrogen sulfide, chlorides, etc., as well as the rapid destruction of the coating under the direct action of light fluxes and the use of toxic hardeners.

The purpose of the invention is to increase the anticorrosion and physicomechanical properties of coatings.

The goal is achieved by the fact that the composition contains isomethyltetrahydroflate anhydride as a hardener and, additionally, thioneaphene-formaldehyde resin, a co-product of formaldehyde purification of naphthalene with a density of 1.13-1.18 r / cm3, a specific viscosity of 20-200 s with the following ratio of components, wt.%:

Epoxy Dianova

resin 10-12

Polystyrene8-10

Thioneften-formaldehyde resin associated product

formaldehyde

cleaning naphthalene 10-13

Isomethyltetrahydrophthalic anhydride 2-5

TolueneErest

Isomethyltetrahydrophthalic anhydride is known in practice as a hardener of epoxy compositions, operating under conditions of high temperatures (120-170 ° C). At the same time, Isomethyltetrahydrophthalic anhydride (IMTHPA) according to TU 30.10349-85 is a easily crystallizing liquid, well soluble in toluene, benzene, ether, acetone.

In the proposed composition under conditions of temperatures of 30-60 ° C, Isomethyltetrahydrophthalic anhydride was not only used as a hardener, but also turned out to be an inhibitor of underfilm corrosion, i.e. performed in a new capacity

The hydrocarbon formaldehyde resin (CFS) is formed during the formaldehyde purification of naphthalene from thiophene and is mainly a condensation product of the latter with formaldehyde. SUF is a thick, viscous product, dark brown in color with a density of 1160-1180 kg / m3.

Conditional viscosity at Szo and Cso is between 20–200 and 45–200 s.

Elemental composition,%. C 85-87, H 5.7-5.8; O 2.4-2.6; N 0.18-0.3; S 4,6-6.0 Molecular weight 300 (TU 14-6129-76).

In the proposed composition, the SF coating acts as a plasticizer, as well as in a new function as a hardening accelerator. As a result, a film coating is formed, which is characterized by increased physicomechanical strength, which ensures a decrease in the rate of underfilm corrosion on the metal surface. 5 The composition for anti-corrosion coatings is prepared as follows.

At a certain ratio of the components involved in the composition, the polystyrene is first mixed with solvent 0 (toluene) until it is completely dissolved (4-6 hours). The process of dissolving polystyrene is carried out at room temperature. Then, while stirring the reaction mixture, epoxy 5 resin, SUF and IMTHPA are sequentially added to it, after which toluene is added to bring the viscosity to 30–40 s. In this state, the composition is ready for operation. Its curing after deposition of 1 on the metal plate occurs at 30-80 ° C.

Example. 10 g of polystyrene were mixed at room temperature with 50 ml of toluene (d20 0.866) for 4 hours. Then 10 g of epoxy resin, 10 g of SUF 5 and 35 g of isomethyltetrahydrophthalic anhydride were added to the mixture. After that, another 20 ml of toluene was added to obtain a formulation with a viscosity of 35 seconds. The composition of the coating corresponded to the following ratio of the participating components, wt.%:

Epoxy

resin10

Polystyrene10

Hydrocarbon - 5formaldehyde

resin10

IMTHP3,5

Toluene Else to 100

The composition was applied to the prepared 0 degreased sample surface and after drying the coating was tested for impact (GOST 4765-79), bending (GOST 6806-83) and adhesion (GOST 15140-78).

The following results were obtained: the strength of the film against impact was 50 kg / cm2; durability of a film to a bend of 1 mm; adhesion 1 point; curing time 30 min at 18-22 ° C.

Table 1 shows experimental data illustrating the influence of the fate of each of the components of the coating composition.

These data indicate the presence of mutual effects of the components involved in the composition, both on the strength characteristics and on the rate of subsurface corrosion. However, participation in the composition of SUF, ED-16, and especially polystyrene in an amount more than optimal, leads to an increase in the corrosion rate, i.e. to the deterioration of quality indicators of coverage.

Table 2 also gives data describing the participation of each of the components and the entire population for the duration of the curing of the coating.

Thus, only the complete set of components involved can significantly affect the cure time,

Table 3 presents data illustrating the effect of curing temperature on the properties of coatings obtained on the basis of the proposed composition (coating thickness 20-22 µm).

Thus, within the specified temperatures, a complete cure of the coating is achieved, characterized by satisfactory quality indicators.

Table 4 presents experimental data confirming the anticorrosive properties of isomethyltetrahydrophthalic anhydride together with a hydrocarbon-formaldehyde resin.

The function of isomethyltetrahydrophthalic anhydride as a corrosion inhibitor in combination with SUF was evaluated through the electrochemical properties of protective coatings containing the indicated components.

The measurement was carried out using the P-5827 M guantizstat in a three-electrode cell (electrochloride – silver – silver electrolyte, auxiliary – platinum), at room temperature in the potentiodynamic mode at a sweep rate of 3 V / h. Currents and rates of subfilm corrosion were calculated at the initial portions of the Taffel slope of the curves using the Stern equation. Samples were exposed in 3% NaO solution.

Table 5 shows comparative indicators of the quality of the coatings of the proposed composition and known.

Claims (1)

Invention Formula A coating composition comprising an epoxy resin Dianova, polystyrene, a hardener and toluene, characterized in that. that, in order to increase the anticorrosive and physicomechanical properties of the coating, it contains isomethyltetrazhydrophthalic anhydride as a hardener and additionally thioneften-formeldehyde resin - a by-product of formaldehyde purification of naphthalene with a density of 1.13-1.18 g / cm3, conditional viscosity 20- 200 s, in the following ratio, wt.%: Epoxy Dianova resin 10-12 Polystyrene8-10 Said thioneaphene formaldehyde resin associated product formaldehyde cleaning naphthalene 10-13 Isomethylene tetrahydrophthalic anhydride2-5 TolueneErest Table 1 five 0 five 0 five Continuation of table 1 Component composition Sub-film corrosion current, A / cm2 ES8% .SUF 11% polystyrene 9% IMTHPA 1.6% Also + IMTGFA2.0% Also + IMTHPA 3.5% The same + IMTHPA 5% The same + IMTHPA b% table 2 Table 3 Table 4 Subfilm corrosion rate. mm / year 10-6 10-7 10-7 10-7 10-7 0.02350 0.00230 0.00228 0.00232 0.00340 Table 5