RU2358998C2 - Composition and system for anticorrosion coating - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: proposed composition consists of a semi-finished product and a hardener of polyisocyanate biuret No 31. The semi-finished product has the following ratio of components, in wt pts.: 42.0-55.4 epoxy-melamine-polyester lacquer "ЭП-074" with 55.4% content of non-volatile substances, 33.3-40.8 white titanium pigment TiO₂ with rutile structure, 1.4-5.8 synthetic aerosil silica A-175 and 4.0-5.2 talcon MM-20 microtalc as filler, 4.7-19.0 P-189 solvent. The hardener is taken in quantity of 8-13.5 wt.pts per 100 wt pts of semi-finished product. The system of anticorrosion coating comprises a top layer, intermediate layer and a bottom layer. The top and intermediate layers of the system are made from the above mentioned composition. The bottom layer of the system is made from epoxide base coating material "ВГ-33", which contains specularite pigment.

EFFECT: invention increases adhesion to steel at low hardening temperature, impact strength and elasticity, increases the service life of the coating system.

2 cl, 5 tbl, dwg

Description

The invention relates to the field of corrosion protection of basic structural materials / steel / and can be used as a protective coating for marine vessels and floating platforms in highly saline / sea / water conditions.

Known varnish brand EP-730 / GOST 20824-81 /, having a chemical composition / wt.h./: epoxy resin of the diane type E-41 0.3-0.35; a mixture of organic solvents (acetone, xylene, ethyl cellosolose), taken in the ratio of 4: 3: 3, or solvent P-5 0.7-0.65; hardener No. 1 / solution of hexamethylene in ethyl alcohol / 0.03.

The varnish is intended for the protection of aluminum, steel and nonmetallic surfaces of products working in conditions of high humidity, the action of alkali solution, alcohol-gasoline mixture.

The disadvantages of this varnish are insufficiently reliable adhesion to the substrate, whitening of the coating, indicating the onset of destructive processes in the paintwork. At the same time, water absorption, vapor permeability increases significantly and weather resistance decreases.

Known composition for anti-corrosion coating, including epoxy resin, solvent and pigments, which are used as aluminum or zinc powder / Protasov V.N. The effectiveness of the use of anticorrosive coatings for oilfield equipment. M .: VNIIOENG. - 1984.- P.44-45.

The disadvantage of this composition is the limited resistance of the coatings to certain types of corrosion / abrasive wear, pitting, cavitation /. Another disadvantage is the gas evolution during the reaction with aggressive acidic and alkaline media, loosening the coating structure and sharply worsening its protective properties.

Closest to the invention in technical essence is a composition for anti-corrosion coating, consisting of 8-14 parts by weight hardener and 85-91.5 wt.h. semi-finished product. As a hardener, a fluorine-containing oligomer OF-2 is used in the form of a 50% solution. As a semi-finished product using epoxy varnish EP-076 containing a solution of epoxy resin. This source also describes a system for anticorrosion coating, containing the upper layer and the lower layer formed from the above composition / RU 2067105 C1, 09/27/1996 /.

The disadvantage of this composition and system is the short life of the coating when exposed to highly saline sea water and increased toxicity.

Also known is a system for anti-corrosion coating, including the upper, intermediate and lower layers, made on epoxy paints / Finkelstein M.I. Industrial application of epoxy paints and varnishes. - L .: Chemistry, 1983. - p. 75-78 /.

The disadvantage of this system is the short service life / 2-3 years /, due to the low adhesion of the coating to the surface and the small thickness of the layers.

The objective of the invention is to provide a composition and system for anticorrosive coating of marine vessels that operate reliably in highly mineralized / sea / water conditions and increase the service life of the coating system.

The technical result of the claimed invention is to improve the basic technical characteristics of the coating and increase the service life of the anti-corrosion coating system in highly mineralized / sea / water conditions.

The technical result is achieved in that the proposed composition for anticorrosion coating according to claim 1 and the system for anticorrosion coating according to claim 2 differ from the known ones in that the composition contains EP-074 epoxy-melomino-polyester varnish containing non-volatile substances 55, 4%, as a hardener - polyisocyanatobiuret No. 31, in addition the semi-finished product contains a pigment titanium titanium white TiO _{2 of a} rutile structure, fillers synthetic silica - A-175 and microtalc talcone MM-20 and solvent R-189; in a system including the upper layer, the intermediate layer and the lower layer, the upper layer and the intermediate layer are made of the composition according to claim 1, and the lower layer is made of epoxy paint and varnish material - primer VG-33 containing pigment speculary.

The essence of the invention lies in the fact that the use of modified with components / titanium whiteness TiO ₂ rutile structure, synthetic silica - Aerosil A-175, microtalc talcone MM-20 / epoxy-melamine-polyester varnish EP-074 together with hardener polyisocyanatobiuret No. 31 in the proposed quantities provides the possibility of "cold" drying of the coating with high protective properties of the composition and coating under the influence of sea water and ultraviolet radiation of the solar spectrum. Provides compatibility of the proposed composition with an epoxy-silicone coating based on the primer VG-33 in multilayer anti-corrosion systems on ships.

EP-074 / TU 6-10-1030-76 / - epoxy-melamine-polyester varnish. The specified varnish is used without hardener and only with hot drying at a temperature of 150-170 ° C. The presence of hydroxyl groups in the varnish ensures the interaction, and, consequently, its curing with polyisocyanatobiuret No. 31.

Varnish EP-074 / TU 6-10-1030-76 / is a solution of epoxy resin E-49, melomino-formaldehyde resin K-421-04 and L24K polyester in organic solvents. Film adhesion no more than 2 points. Drying time to degree 3 at a temperature of / 150 ± 5 / ° С no more than 1 hour.

White titanium TiO ₂ rutile structure / GOST 9808-84 /. Main properties: synthetic achromatic, corrosion-neutral white pigment. The particle size is about 0.3 microns. The reflection in the visible part of the spectrum is at least 95%. Provides the stability of the composition when exposed to ultraviolet radiation from the solar spectrum.

Synthetic silica - Aerosil A-175 / GOST 14922-77 / is an almost pure SiO ₂ / 99.4-99.8% /. It has thixotropic properties. It is characterized by an extremely high degree of dispersion, particle size from 0.15 to 0.02 microns. When dispersed in a medium, only part of their surface is wetted; they form bulk coagulation networks. Such nets include pigment particles and prevent their deposition, increase the viscosity of the dispersed medium. Aerosil A-175 is a loose bluish-white powder. Mass fraction of the main substance SiO ₂ 99.8%. Mass fraction of moisture no more than 2%.

Mikrotalk - talcon MM-20 / TU 5727-001-49439345-2002 /. It is a natural mineral with a particle size of 6 to 20 microns. Bulk density of 0.2-0.4 g / cm ³ . Helps optimize the structure of formed coating films.

Hardener polyisocyanatobiuret No. 31 / TU 6-2 7-217-2001 /. It is an aliphatic isocyanate. Provides weather resistance coatings based on epoxy-melomano-polyester varnish.

Solvent P-189 is a mixture of solvents: methyl ethyl ketone, ethyl glycol acetate, xylene and butyl acetate. The main requirement for these solvents is an extremely low water content / not more than 0.15% /. Otherwise, excess water will actively interact with the isocyanate groups of the hardener, sharply inhibiting its activity.

Primer VG-33 / TU 2312-004-29727639-97 / with pigment speculary / ISO 1248-74 /. The primer VG-33 is supplied complete in the form of two components of the semi-finished product of the primer VG-33, which includes a film-forming substance / solution of epoxy resin E-41 / and specular, and hardener ASOT-2 in the ratio / wt.h./ 100/17, respectively .

Technical characteristics of VG-33. The elasticity of the film in bending, mm, not more than 5. The strength of the film upon impact on the device U-1A, J, not more than 5. Adhesion, points, not more than 1. Drying time to degree 3 at a temperature of / 20 ± 2 / ° С, h 6. Mass fraction of non-volatile substances in the semi-finished primer,%, 45-55.

The composition is prepared as follows. EP-074 varnish, TiO ₂ titanium white and MM-20 microtalc Talcone according to the recipe are loaded into the mixer, mixed thoroughly until the pigment and filler are evenly distributed, and then dispersed in a bead mill with water cooling for 2 hours, periodically checking the degree of grinding on the "wedge". Upon reaching a milling degree of 15 μm, Aerosil A-175 is loaded into a bead mill and dispersed to a milling degree of 15 μm. Then the solvent R-189 is loaded into the bead mill, mixed and discharged into a container. In the semi-finished product, the conditional viscosity, the degree of milling and the content of non-volatile substances are determined.

The degree of milling of the manufactured compositions was determined in accordance with GOST 6589-72, viscosity - in accordance with GOST 8420-74 with a B3-246 viscometer with a nozzle diameter of 4 mm, the mass fraction of non-volatile substances in the compositions was determined in accordance with GOST 15537-72, the drying time of coatings was determined in accordance with GOST 19007- 73.

The protective properties of coatings are determined on steel samples st.3 with sandblasting. The tests were carried out in a salt spray chamber according to STP VIAM 1-595-7-354-2001, as well as by immersion of samples in a 3% NaCl solution.

Physicomechanical properties / coating strength and elasticity / are determined according to GOST 4765-73 and OST 6-10-411-77, respectively, the coating hardness after drying is determined according to GOST 5233-67.

The adhesion of the coatings is determined according to GOST 15140-78 / by the method of trellised notches /.

The invention is illustrated by the examples given in the tables: in table 1 shows the formulations of prototypes of the composition based on EP-074 varnish, in table 2 - the main indicators of the properties of the prepared formulations of the composition, in table 3 - adhesive and physico-mechanical properties of the primer coating system VG-33 + 2 layers of the proposed composition, in table 4 - adhesive and physico-mechanical properties of the primer system VG-33 + 2 layers of the proposed composition after thermal aging, in table 5 - the results of determining the protective properties of the coating based on the proposed composition.

The drawing shows the kinetics of curing coatings based on the proposed composition, cured with isocyanate hardener No. 31: 1 - 100 wt.h. the proposed composition of 8.0 parts by weight hardener No. 31; 2 - per 100 parts by weight the proposed composition of 11.0 parts by weight hardener No. 31; 3 - per 100 parts by weight the proposed composition of 13.5 parts by weight hardener No. 31.

From the data in table 2 it follows that the mass fraction of non-volatiles in the composition increased significantly / 60-77.3% /, and the drying time of the coating decreased / up to 4-5 hours /, which positively affects the economic indicators of the proposed composition.

To cure the proposed composition at a temperature of / 20 ± 2 / ° C, you must enter 8-13.5 wt.h. hardener polyisocyanatobiuret No. 31 per 100 parts by weight varnish. With the introduction of the hardener less than the declared amount, the drying time of the coating increases more than acceptable, and with the introduction of the hardener more than the declared amount, the adhesion and strength of the coating decreases.

The indicated results are also due to the use of rutile titanium white oxide, synthetic silica - Aerosil A-175, microtalc talcon MM-20 in the indicated amounts.

Aerosil A-175, which is part of the composition in an amount of 1.4-5.8 parts by weight, plays the role of a structuring additive that provides for the formation of a bulk coagulation network in the composition, which contributes to an increase in the thickness of the coating layer, gives the composition stability during storage. With the introduction of this component is less than 1.4 wt.h. the composition does not provide the required layer thickness, with the introduction of more than 5.8 wt.h. the viscosity of the composition exceeds the desired value.

Microtalc, which is included in the composition in an amount of 4.0-5.2 wt.h, has an effect on the drying time and coating strength. With the introduction of microtalc less than 4.0 wt.h. drying time increases more than permissible, and with the introduction of microtalc more than 5.2 wt.h. coating strength is reduced.

The developed formulation of the composition was investigated as a protective coating for the protection of ship hulls in a system with a VG-33 anticorrosive primer coating. The properties of the coating system were determined on steel samples st. 3 with sandblasting. The coating of the composition was applied in two layers on the primer VG-33 and cured at a temperature of 20 ± 2 ° C for 5 days. From the results shown in table 3, it is seen that the coating system, consisting of 1 layer of primer VG-33 and two layers of the proposed composition, has high adhesion to steel st. 3 and physical and mechanical characteristics.

The results obtained in determining the adhesive and physico-mechanical properties of the coating composition based on the proposed composition after thermal aging are shown in table 4. As can be seen from the results obtained, the artificial aging of the coating system based on the proposed composition does not impair its adhesive properties and impact strength, but leads to a slight decrease in the elasticity of the coating. Such a decrease in elasticity is associated with the processes of additional structure formation that occur at elevated temperatures. However, even after artificial aging, elasticity remains high.

From the data given in table 5, it follows that coatings based on the proposed composition and primer VG-33 have high protective properties in conditions of salt fog and immersion in a 3% NaCl solution.

Thus, the supply of the composition based on EP-074 epoxy-melamine-polyester varnish with additional titanium whitewash of the rutile structure, the introduction of synthetic silica - Aerosil A-175 and microtalcum talcone MM-20 and the use of hardener polyisocyanatrate No. 31 can significantly expand the operational capabilities of the composition and apply it for effective protection of hulls of marine vessels in the anti-corrosion coating system. The expected life of the coating is more than 10 years.

Table 1 Formulations of prototypes of a composition based on varnish EP-074 Components The content of components, parts by weight one 2 3 four 5 6 7 8 Varnish EP-074 (containing non-volatile 55.4%) 56.2 55,4 48.8 51.1 49.6 43.9 42.0 40,0 Titanium white 33.8 33.3 39.0 40.8 39.6 35.0 33.0 24.0 Microtalc 5.2 5.2 4.9 5.1 5,0 4,5 4.0 3.0 AerosilA-175 - 1.4 - 3.0 5.8 4,5 2.0 2.0 Solvent R-189 4.8 4.7 7.3 - - 11.5 19.0 21.0

In table 1, examples 7 and 8 are comparative

table 2 The main indicators of the properties of the prepared formulations Property metrics Formulations of Manufactured Compositions one 2 3 four 5 6 7 8 Viscosity by viscometer B3-4, s 107.1 106.5 70.3 108,0 115,2 60.0 47.0 45.0 The degree of milling, microns twenty twenty twenty twenty fifteen fifteen twenty twenty Mass fraction of nonvolatile substances,% 70.3 70.6 71.0 77.3 75.1 67.0 60.0 55.0 Drying time to degree 3, h 6 6 5 5 four four 5 5

Table 3 Adhesive and physico-mechanical properties of the coating system primer VG-33 + 2 layers of the proposed composition Surface preparation Thickness, microns Adhesion points Physical and mechanical properties Source After 1 day, moist. After 7 days wet. Impact Strength, J Elasticity, mm Sandblasting 80-100 one one one 5,0 6.5 Stripping with a glass skin 70-90 one one 1-2 5,0 6.6

Table 4 Adhesive and physico-mechanical properties of the coating system Primer VG-33 + 2 layers of the proposed composition Surface preparation Thickness, microns After thermal aging (-60 ... + 80) ° С for 10 cycles Adhesion according to GOST 15140-78 Physical and mechanical properties Source After 1 day of hydration After 7 days of hydration Impact Strength, J Elasticity, mm Sandblasting 85-95 one one one 5,0 5,4 Stripping with a glass skin 75-80 one one one 5,0 5.5

Table 5 The results of determining the protective properties of the coating based on the proposed composition Coating system Surface preparation Sample condition after exposure Salt spray chamber Immersion in 3% solution of NaCl 1 month 3 months 1 month 3 months Primer VG-33 + proposed composition Sandblasting Coverage Unchanged Coverage Unchanged Cover unchanged Coverage Unchanged Stripping with a glass skin Coverage Unchanged Coverage Unchanged Coverage Unchanged Coverage Unchanged

Claims (2)

1. Composition for anticorrosion coating, consisting of a semi-finished product containing epoxy-melamine-polyester varnish EP-074 with a non-volatile content of 55.4%, a titanium white pigment TiO _{2 of a} rutile structure, fillers - synthetic silica - Aerosil A-175 and microtalc talcone MM-20, solvent R-189, and hardener polyisocyanatobiuret No. 31 in the following ratio of components in the semi-finished product, parts by weight:
EP-074 epoxy-melamine-polyester varnish with a content of non-volatiles 55.4% 42.0-55.4 the above titanium white 33.3-40.8 the above aerosil A-175 1.4-5.8 the above microtalc 4.0-5.2 solvent R-189 4.7-19.0
and the above hardener is taken in an amount of 8-13.5 parts by weight per 100 parts by weight the above semi-finished product. 2. A system for anti-corrosion coating, comprising a top layer, an intermediate layer and a lower layer, characterized in that the upper layer and the intermediate layer are made of the composition according to claim 1, and the lower layer is made of epoxy paint and varnish material - primer VG-33 containing pigment speculates.