CN106867297B

CN106867297B - Special water replacement type preservative for airplane

Info

Publication number: CN106867297B
Application number: CN201710058007.2A
Authority: CN
Inventors: 张金娜; 王晓艳; 李晓楠; 徐小艳; 王可伟
Original assignee: BEIJING YADILITE AVIATION CHEMICALS Co Ltd
Current assignee: BEIJING YADILITE AVIATION CHEMICALS Co Ltd
Priority date: 2017-01-23
Filing date: 2017-01-23
Publication date: 2020-02-14
Anticipated expiration: 2037-01-23
Also published as: CN106867297A

Abstract

The invention discloses a water replacement type preservative special for an airplane. Which comprises the following components in parts by weight: 40-50% of solvent, 30-50% of film forming agent, 5-10% of drier, 1-5% of flexibilizer, 0.1-2% of water displacer, 0.1-2% of corrosion inhibitor, 0.1-2% of flatting agent and 0.1-0.3% of dye. The components are mixed uniformly according to the proportion to form uniform transparent yellow to brown liquid. The invention has the advantages of good water replacement property and easy cleaning, and can reach the durability of 1500 hours in a salt spray test, the surface curing can be achieved within 3 hours, and the operation time is shortened.

Description

Special water replacement type preservative for airplane

Technical Field

The invention relates to the field of metal preservatives, in particular to a water replacement type preservative used in the maintenance process of civil aircrafts and a preparation method thereof.

Background

Corrosion is a difficult problem encountered in the process of maintenance of civil aircrafts. Corrosion-related aircraft repairs have been a significant portion of the total cost to maintain an airline, paying billions of dollars per year for corrosion repairs by airlines throughout the world. The international aviation association 1983 statistical report shows that: the corresponding corrosion repair costs per flight hour for an aircraft have reached $ 10 to $ 24. The expense is not the large stock of aircraft materials prepared by the airline to ensure proper operation of the aircraft and the repair loss due to corrosion at the unscheduled parking lot.

Corrosion can lead to elevated structural stress levels. When the load-bearing capacity of the structure is reduced below the fail-safe load, the structure is likely to break under the static load (fail-safe load). The formation and propagation of fatigue cracks can lead to increased rates and premature failure of the structure due to increased stress levels in the structure. Corrosion may also lead to loss of function of the aircraft system. Therefore, the corrosion problem not only relates to the economic problem, but also seriously jeopardizes the flight safety of the aircraft.

Coating the preservative on the surface of the aircraft structure is the most widely applied mature measure at present, and the cost of the preservative for domestic airlines and maintenance enterprises is about 1000-. However, all preservatives in boeing and air passenger manuals are currently imported and are relatively costly. With the coming of the domestic aircraft C919, research and development of domestic preservatives are urgently needed so as to reduce the dependence of domestic markets on imported products.

Water-displacing preservatives are also known as mild preservatives. It consists of a volatile solvent and non-volatile organic compounds dissolved therein. It has strong permeability and can permeate into extremely small gaps and pores. After the solvent is volatilized, a thin film is formed to replace the originally adsorbed moisture on the surface and cover the surface again. Corrosion does not occur due to the lack of electrolytic solution necessary for corrosion generation. Corrosion that has already begun can also result in a significant decrease in the rate of corrosion diffusion (but cannot prevent the continued slow diffusion of corrosion) due to the lack of electrolyte solution. Therefore, the water replacement type corrosion inhibitor can not only prevent the occurrence of corrosion, but also delay the propagation speed of the corrosion. Such preservatives form a relatively thin protective film and add little weight to the aircraft. The defects are that the durability of the salt spray test is poor, the water replacement performance is poor, the curing time is long, and the cleaning is difficult.

Disclosure of Invention

In order to solve the above-mentioned problems, an object of the present invention is to provide a water-displacing type preservative for aircraft, which has a durability in a salt spray test of 1500 hours, is excellent in water-displacing performance, is surface-cured for 3 hours, and is easy to clean.

The present inventors have conducted extensive studies to achieve the above-mentioned objects, and have unexpectedly found that the above-mentioned technical problems can be well solved by a water-displacement preservative system having a specific composition, thereby achieving the object of the present invention, and meeting and adapting to the special requirements of maintenance of civil aircraft.

A water-displacement preservative for aircraft, comprising the following components, based on the total amount of the preservative:

in the preservative of the invention, the solvent is any one or more selected from D40, D60, isoparaffin solvent naphtha and No. 120 gasoline. The solvent is used for dissolving the film forming agent and the auxiliary agent. The several solvents selected in the present invention have the following advantages: the film-forming resin has good compatibility with various additives, and does not generate precipitation or delamination after being placed for a long time; does not contain aromatic hydrocarbon and is harmless to human bodies and environment; the volatilization speed is moderate, and the preservative is easy to form a film and solidify.

In the preservative, the film forming agent is selected from any one or more of C5 petroleum resin, C9 petroleum resin, C5/C9 copolymer resin, alkyd resin, phenolic resin, terpene resin and liquid petroleum resin. The film forming agent has the function of covering the surface of the airplane structure to form a film after a solvent in the preservative is volatilized, so that the continuous occurrence of corrosion is slowed down. The present invention selects a resin as a film former. The requirements for screening resins are: 1) the solubility parameters of the resin and the solvent are similar, so that the thickness of the film layer can be ensured; 2) the softening point of the resin is about 130 ℃, so that the toughness of the formed resin film is ensured, and the formed resin film is not too brittle or too sticky; 3) the molecular weight of the resin is mainly concentrated between 600-1200, the molecular weight is too low, the weather resistance of the formed film of the resin is poor, the molecular weight is too high, the viscosity of the resin is too large, and the uniform distribution of other auxiliary agents in the preservative is not facilitated. The thickness of the film formed by the resin selected by the invention is about 35 mu m, the toughness of the formed film is moderate, and the viscosity is moderate.

In the preservative, the drier is selected from any one or more of propylene glycol butyl ether, ethylene glycol butyl ether, propylene glycol methyl ether, ethylene glycol methyl ether, propylene glycol ethyl ether and ethylene glycol ethyl ether. The resin drier is used for adjusting the volatilization speed of the solvent and dissolving the resin. The drier selected by the invention has good compatibility with the solvent and the film forming agent and moderate volatilization speed.

In the preservative of the invention, the toughening agent is selected from any one or more of cottonseed oil, castor oil, peanut oil and soybean oil. The toughening agent has the effects of reducing the brittleness of a formed film and increasing the toughness through physical blending. The toughening agent selected by the invention is vegetable oil, has natural source and good compatibility with a system, and can effectively improve the brittleness of a formed film.

In the preservative of the invention, the water replacement agent is any one or more selected from AEO-3, OP-4, span 20 and span 40. The water displacer is used for emulsifying water on the metal surface into a preservative system, and an oil film is further covered on the metal surface, so that the corrosion of the water to the metal is reduced. The water displacing agent is a surfactant having both lipophilic and hydrophilic groups to ensure that it can emulsify water into an oily system, a preservative. The water displacer HLB value selected by the invention is between 6 and 8, is an effective emulsifier of a water-in-oil system, and is suitable for the preservative system.

In the preservative, the corrosion inhibitor is selected from any one or more of benzotriazole, organic phosphate, barium petroleum sulfonate and sodium petroleum sulfonate. The slow release agent has the functions of ensuring that the whole preservative system has no corrosion to metals and preventing or slowing down the corrosion of foreign substances such as (such as water and salt) to the metals.

In the preservative of the present invention, the leveling agent is an acrylate leveling agent. The leveling agent has the functions of promoting leveling and preventing foaming. The acrylate compounds are various, and according to the analysis of molecular structures, the longer the side carbon chain of the acrylate compound is, the lower the surface tension is, and the corresponding polarity and solubility parameters become smaller. When the polarity and solubility parameter of the acrylate are smaller than those of the resin, the acrylate can be used as a leveling agent of the resin. In addition, the molecular weight of the acrylate leveling agent is generally less than ten thousand, so that the leveling agent can be rapidly transferred to the surface to play a role. In the invention, different acrylates are selected as the leveling agent according to different types of film-forming resins.

In the preservative of the present invention, the dye is a mixture of red and brown dyes. The metal surface of the airplane is coated with the gray primer and the white finish, and the corrosion inhibitor has proper color to ensure the observability of the coating, thereby facilitating the daily operation. The invention selects the red dye and the brown dye to be compounded into the yellow to brown dye, and has good compatibility with a system and good dye color stability.

The invention also aims to provide a preparation method of the special water replacement type preservative for the airplane, which is characterized by comprising the following steps: the method comprises the following steps: adding the film forming agent into a reaction kettle, heating to melt, adding the solvent, uniformly stirring, cooling to room temperature, sequentially adding the drier, the flexibilizer, the water displacer, the corrosion inhibitor, the flatting agent and the dye, and stirring until the system is uniform and transparent to obtain a finished product.

The invention has the following beneficial effects:

the durability in the salt spray test can reach 1500 hours, the water replacement performance is good, the complete curing can be achieved in 3 hours, the cleaning is easy, and the operation time is reduced.

Detailed Description

The embodiments of the present invention and the advantageous technical effects thereof are further described below with reference to specific examples, but it should be understood by those skilled in the art that the present invention is not limited to the contents of these specific embodiments and examples.

In the examples, "parts" means "parts by weight", "proportion" means "weight ratio", and "%" means "weight percent", unless otherwise specifically indicated.

Example 1:

example 2:

example 3:

example 4:

example 5:

example 6:

example 7:

example 8:

example 9:

example 10:

example 11:

example 12:

example 13:

comparative example 1

comparative example 2:

comparative example 3:

comparative example 4:

the preparation method of the preservative in the embodiment comprises the steps of adding the film forming agent into a reaction kettle, heating to be molten, then adding the solvent, uniformly stirring, cooling to room temperature, sequentially adding the drier, the flexibilizer, the water displacer, the corrosion inhibitor, the flatting agent and the dye, and stirring until the system is uniform and transparent to obtain the finished product.

And (3) performance testing: the test is carried out according to the test outline written by the Boeing standard BMS 3-29.

1) Curing time

Coating and drying were carried out according to the following procedure, and after drying the preservative-coated test panels, surface curing had to be achieved after 3 hours.

(1) Scrubbing and naturally drying 4 x 6 inch 2024-T3 uncoated aluminum alloy with acetone;

(2) the appropriate open vessel is selected to have sufficient depth and volume to ensure that the test panel can be vertically immersed in the test solution.

(3) The required amount of preservative was slowly poured into the container, taking care to reduce entrapped air.

(4) The test panel was immersed vertically in the preservative for at least 1 minute and pulled vertically at a rate not exceeding 12 inches/minute, taking care that no air bubbles were present on the surface of the test panel. The preservative-coated test panels were hung vertically at room temperature for 3 hours

And (3) test results:

using the products of examples 1-10, after 3 hours, the test panel surface preservative had dried and was palpable by hand with no sticky feel.

Using the products of examples 11-12, after 2 hours, the test panel surface had dried and was touchable by hand without a sticky feel.

With the product of comparative example 3, after 4 hours, the surface preservative of the test panel had not dried and had a sticky feeling.

2) Salt spray test

The test was performed according to BSS7249(95 degrees Fahrenheit, 5% NaCl solution). Test panels were coated as described above under 1), 3 test panels were taken as a batch and air dried for 72 hours before the salt spray test was performed. A maximum of 3 corrosion points of 1 mm or more per 10 square inches of aluminum plate after 1500 hours of exposure is required.

And (3) test results:

using the products of examples 1-10, a maximum of 3 corrosion sites were present on a 10 square foot aluminum panel after 1500 hours of exposure, all within 1 mm in diameter.

Using the product of example 13, 10 square foot aluminum panels were free of corrosion spots after 2500 hours exposure.

With the product of comparative example 1, 8 corrosion sites were present on a 10 square foot aluminum panel after 1500 hours exposure, ranging in diameter from 2 to 5 millimeters.

3) Water displacement performance

The assay was performed as part 4.6.14 of MIL 16173. The sheet used for the test was 2 x 3 x 1/6 foot high carbon steel. The test procedure was as follows:

(1) 50 ml of preservative and 5 ml of distilled water were added to a 125 ml beaker, mixed well, sealed and left at 130 degrees Fahrenheit for 24 hours, and then the beaker was cooled to 77 degrees Fahrenheit.

(2) A high carbon steel test plate is vertically immersed in distilled water for no more than 5 seconds, and the bottom is blotted dry with filter paper.

(3) And (3) horizontally placing the medium-high carbon steel test plate in the step (2) in the step (1) for 15 seconds.

(4) The test panel was removed and placed in a desiccator at a temperature of 77 degrees Fahrenheit,

(5) The test panel is cleaned with a preservative and inspected for rust, pitting or other corrosion.

And (3) test results: with the products of examples 1-13, the high carbon steel test panels did not show any corrosion on the surface.

With the product of comparative example 2, corrosion occurred on the surface of the high carbon steel test panel.

4) Cleaning performance

The preservative coated on the board can be completely removed by aliphatic hydrocarbon solvent, such as P-D680 or TT-N-95 white oil at any time.

And (3) test results:

using the products of examples 1-10, the wet corrosion inhibitors on the 4X 6 inch aluminum panels were cleaned three times and the dry corrosion inhibitors on the 4X 6 inch aluminum panels were cleaned 5 times using a QFS type paint scrub tester.

Using the products of examples 12-13, the wet corrosion inhibitor on the 4X 6 inch aluminum panels was cleaned two times and the dry corrosion inhibitor on the 4X 6 inch aluminum panels was cleaned 3 times using a QFS type paint scrub tester.

Using the product of comparative example 4, the wet corrosion inhibitor on the 4X 6 inch aluminum panel was cleaned 6 times and the dry corrosion inhibitor on the 4X 6 inch aluminum panel was cleaned 13 times using the QFS type paint scrub resistance tester.

Claims

1. The special water replacement type preservative for the airplane is characterized by comprising the following components in percentage by weight based on the total amount of the preservative: