RU2480499C2 - Protective coating composition - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to polymer compositions based on modified epoxide oligomers, and specifically to protective coating compositions of composite materials and is recommended for protecting the inner surface of aircraft integral fuel tanks made from polymer composite materials, particularly carbon fibre-reinforced plastic. The protective coating composition of composite materials contains epoxy-diane resin, a modifier - polysulphide rubber, a curing agent - organosilicon amine, a pigment, mineral filler, a reactive diluent - monoglycidyl ether of alkylphenol and an organic solvent. The filler is natural or synthetic magnesium, aluminium or calcium silicates.

EFFECT: obtaining a composition having high fuel- and water-resistance, improved adhesion and physical-mechanical properties during prolonged use in liquid aggressive media.

2 cl, 2 tbl

Description

The invention relates to the field of polymer compositions based on modified epoxy oligomers, namely, compositions for protective coatings and is recommended for protecting the inner surface of the fuel caisson tanks of aircraft made from polymer composite materials (PCM), in particular carbon fiber.

Since the caisson tanks are filled with fuel for the entire life of the aircraft, the life of the structure depends on its resistance to aggressive liquids (fuel, condensate), so it is necessary to protect the carbon fiber with polymer coatings. The coatings must be resistant to the effects of fuel and water, have high adhesive and physico-mechanical properties at operating temperatures from -60 ° C to + (80-100) ° C.

A known composition for coatings, including film-forming, which is a mixture of oligomeric carboxyl-containing butadiene nitrile rubber and epoxy Dianne oligomer, hardener is a mixture of γ- and β-aminopropyltriethoxysilanes, solvent, filler and pigment (RF patent No. 225100).

The disadvantages of the known coating is the low adhesion to carbon plastics and low fuel resistance.

Known anticorrosive composition, including a soluble copolymer of tetrafluoroethylene with vinylidene fluoride, organic solvents - acetone, ethyl acetate, cyclohexanone and amyl acetate, a low molecular weight epoxy resin, amine hardener - a product of the condensation of formaldehyde and phenol with ethylene diamine, a diluent - ethyl bisolide RF patent No. 2331660).

However, the known coating has low adhesion to the surface of the PCM, including carbon fiber, and therefore can not provide high resistance to water and fuel.

A known composition for coating on metal, including a polymer binder - an epoxy diane or epoxy silicone resin, a modifier - polysulfide or butadiene nitrile carboxylate rubber, a hardener - γ-aminopropyl-triethoxysilane, 1-aminohexamethylene-triethoxypropylene-6-aminomethylene-triethoxypropylene filler - barium sulfate, aerosil, talc, titanium dioxide or mixtures thereof, inhibiting pigments - strontium chromate, barium chromate, chromium phosphate or mixtures thereof, organic solution voritel - xylene, acetone, butyl acetate, ethylcellosolve (RF Patent №2260610).

A disadvantage of the known composition for coating on metal is the insufficiently high adhesion to PCM and the water resistance of the coating on PCM during long-term operation.

The known composition of the protective coating for metallic and nonmetallic surfaces, including an epoxy resin modified with a liquid polysulfide oligomer, an amine hardener (China patent No. 101096544).

The disadvantages of the known composition for coating should include the need for curing it at a temperature of 100 ° C, which is unacceptable when painting long panels of PCM.

Known composition for a protective coating for metal "Super primer" containing a water-soluble or water-dispersible resin, as well as a mixture of silanes, leachable inhibitor, which allows the coating to "heal from scratches and damage", as well as nanoparticles (US patent No. 7482421).

However, the known coating has low adhesion to the surface of the PCM and low fuel resistance at elevated temperatures, therefore, cannot be used to protect carbon fiber.

The closest analogue adopted for the prototype is a composition for the protective coating of polymer composite materials, including a binder - an epoxy Dianova resin, a modifier, an amine type hardener, a filler and an organic solvent, which as a binder contains an epoxy Dianova resin or a mixture of epoxy dianes with molecular weighing 1000-3500, as a modifier - low molecular weight epoxyurethane or butadiene-acrylonitrile carboxylate rubber, and as filler - filamentary crystals of zinc oxide or boron nitride in the following ratio of components, parts by weight:

Specified Binder 100.0 The specified modifier 3.0-50.0 Amine hardener 5.0-50 Zinc oxide whiskers or boron nitride 7.0-50.0 Organic solvent 140.0-400.0 (patent No. 2 290421)

However, the prototype does not have a sufficiently high fuel resistance, water resistance, as well as adhesive and physico-mechanical properties during prolonged use in liquid media at operating temperatures from -60 ° C to 80-100 ° C.

The technical task of the invention is the creation of a composition for the protective coating of polymer composite materials with high fuel and water resistance, as well as high adhesive and physico-mechanical properties, during long-term operation in liquid aggressive environments at operating temperatures from -60 ° C to 80-100 ° C.

To solve the technical problem, a composition for a protective coating is proposed, including an epoxy-diane resin, a modifier, a hardener - an organosilicon amine, a pigment, a mineral filler, and an organic solvent, in which it contains polysulfide rubber as a modifier, and additionally contains a reactive diluent monoplycol monophenyl ether with the following ratio of components, parts by weight:

Epoxy Dianne Resin one hundred Modifier 25-50 Hardener 50-100 Reactive Diluent 10-25 Pigment 30-60 Filler 30-100 Organic solvent 150-300

As a hardener, the composition contains an organosilicon amine, a condensation product of γ-aminopropitriethoxysilane (ASOT-2).

The modifier introduced into the composition is polysulfide rubber with a viscosity of 150 P to 300 P and an SH group content of 2.2% to 3.3% (GOST 12812-72), as well as a reactive diluent - alkylphenol monoglycidyl ether (AF laproxide) with a mass fraction of epoxy groups from 10.0% to 14.0% (TU 2225-050-10488057-2009), when cured with organosilicon amine, ASOT-2 enter into chemical interaction with an epoxy binder. In this case, a finely dispersed elastic structure of the modified polymer is formed, which has high adhesive, physico-mechanical properties. The presence of reactive thiol SH-groups in the structure enhances fuel resistance, and the alkylphenol monoglycidyl ether component increases the hydrophobicity (water resistance) of the cured composition.

As a filler using natural silicates of magnesium, aluminum or calcium, such as talc, microtalc, wollastonite.

The use of these fillers contributes to the formation of a denser coating structure, which helps to increase the physico-mechanical properties, hardness, fuel resistance, coating water resistance, as well as resistance to temperature changes.

As an organic solvent, the composition contains xylene, acetone, butyl acetate, ethyl cellosolve, or mixtures thereof.

As the epoxy-diane resin in the present invention can be used resins E-41, E-44, ED-8, ED-10, etc. (TU 6-10-607-78, TU 6-10-1347-75, GOST 10587-84) with a molecular weight from 800 to 1600 and with a mass fraction of epoxy groups from 14.0% to 6.0%.

To impart color to the coating, various pigments may be included in the composition, for example, titanium dioxide, technical carbon, etc. (GOST 9808-84, GOST 7885-77, etc.).

Examples of implementation

The epoxy-diane resin was dissolved in a mixture of organic solvents: xylene, acetone and ethyl cellosolve. Titanium dioxide, microtalc and silicon dioxide (AEROSIL R 812 S) polysulfide rubber, laproxide AF were added to the resulting solution, and the resulting composition was mixed. Before use, the hardener ASOT-2 was introduced into the composition, mixed and adjusted to a working viscosity using a B3-246 viscometer with a mixture of organic solvents: xylene, acetone, butyl acetate.

The proposed compositions for the protective coating and prototype are shown in table 1.

The compositions according to examples (2-8) were made analogously to example 1.

Example 9 (prototype)

Epoxy resin E-41 was dissolved in a mixture of organic solvents: acetone, xylene, butyl acetate, zinc oxide whiskers were introduced. Before use, a modifier (butadiene-acrylonitrile carboxylate rubber in the form of a solution in butyl acetate) and hardener AGM-9 were added to the semi-finished product, mixed and adjusted to a working viscosity with a mixture of organic solvents.

The invention is not limited to the examples given.

From the compositions shown in examples (1-9), coatings 40-60 μm thick were obtained on carbon fiber reinforced plastic, as well as on samples from the aluminum alloy D16AT An.ox.n. (to determine the physical and mechanical properties). Curing of coatings was carried out at a temperature of 60 ° C for 7 h. The thickness of the coatings, the adhesive strength at separation, adhesion according to GOST 15140-78 in the initial state and after wetting for 10 days, fuel swelling, and water absorption were determined. Impact strength, tensile strength were determined on metal in accordance with GOST 4765-73 and OST: -10-411-77 in the initial state and after thermal cycling (-60 ... +100) ° С for 16 cycles, as well as after long tests in fuel TS-1.

The results are shown in table 2.

Table 1 The composition according to examples, parts by weight Prototype Name of components one 2 3 four 5 6 7 8 9 E-41 one hundred - - - one hundred - - one hundred one hundred E-44 - one hundred - - - one hundred - ED-8 - - one hundred - - one hundred - ED-10 - - - one hundred - - Polysulfide rubber 25 thirty 25 40 35 thirty 35 fifty - Laproxide AF 10 eighteen fifteen twenty fifteen 10 twenty 25 - Butadiene acrylonitrile carboxylate rubber - - - - - - - - 17 Fillers: ZnO whiskers - - - - - - - - thirty Talc - - 55 fifteen - 45 eighteen - Microtalc thirty 46 twenty 54 10 twenty thirty Wollastonite - 5 45 10 - 5 10 thirty Pigments: Titanium dioxide 29.5 35 40 fifty 37 35 45 59 40 Technical carbon 0.5 - - one 0.25 0.5 - one - Hardener AGM-9 - - - - - - - - 35 Hardener ASOT-2 70 fifty 62 80 85 82 65 one hundred - Solvents: Xylene 70 80 110 90 90 80 80 120 one hundred Acetone 40 60 85 60 67.5 80 60 90 70 Ethyl cellosolve 40 fifty - - - fifty 60 - - Butyl acetate - - 85 60 67.5 - - 90 155

table 2 Property metrics The proposed composition of the examples Prototype one 2 3 four 5 6 7 8 9 Coating thickness, microns 45 55 60 60 fifty fifty 60 65 160 Adhesive Strength (σ _adh ), MPa 51.6 54.0 55.1 53.0 56.4 55.3 55.9 54.5 54,2 Adhesion to carbon fiber, score - in the initial state one one one one one one one one one - after 30 days of hydration one one one one one one one one 2 Adhesion to carbon fiber after thermal cycling (-60 ... + 100) ° С for 16 cycles, point, - in the initial state one one one one one one one one 2 - after 10 days of hydration one one one one one one one one 2 Fuel swelling after 2000 hours of exposure in fuel,% 0.52 0.49 0.65 0.52 0.45 0.64 0.71 0.68 7.2 Water absorption after 2000 h exposure in distilled water,% 1.65 1,58 1,61 1.48 1,5 1,53 1,61 1.65 3.3 The tensile strength of the coating film in the initial state, mm 5.3 4.7 5.2 5.7 4.9 5,6 5.9 6.2 5,0 The tensile strength of the coating film after thermal cycling (-60 ... + 100) ° C for 16 cycles, mm 5.1 5,0 5.1 5.5 5,0 5.5 5.8 6.0 4.8 The strength of the coating film upon impact after 2000 hours in the fuel at a temperature of 80 ° C, mm 5,0 5,0 5,0 5,0 5,0 5,0 5,0 5,0 2.0 The tensile strength of the coating film after 2000 hours in fuel at a temperature of 80 ° C, mm 5,4 4.7 5,0 5,4 4.9 5.5 5,6 6.6 2,5

As can be seen from the above examples, the use of the invention in comparison with the prototype allows to increase the adhesion after 10 days of wetting from 2 points to 1 point (according to GOST 15140-78), the performance of the coating after lengthy tests in fuel: fuel swelling (10-14) times, water absorption (2.0-2.3) times, the strength of the coating film upon impact 2.5 times, the tensile strength of the coating 2.0-2.4 times.

The use of the composition for the protective coating of polymer composite materials provides long-term protection of fuel caisson tanks during operation in liquid aggressive environments at a temperature difference from -60 ° C to 80-100 ° C.

Claims (2)

1. The composition for the protective coating of polymer composite materials, including epoxy-diane resin, a modifier, a hardener - an organosilicon amine, a pigment, a mineral filler and an organic solvent, characterized in that it contains polysulfide rubber as a modifier and further contains a reactive diluent alkylphenol monoglycidyl ether in the following ratio of components, parts by weight:
Epoxy Dianne Resin one hundred Modifier 25-50 Hardener 50-100 Reactive Diluent 10-25 Pigment 30-60 Mineral filler 30-100 Organic solvent 150-300 2. The composition for the protective coating of polymer composite materials according to claim 1, characterized in that as a filler it contains natural silicates of magnesium, aluminum or calcium.