HUT63102A - Method for removing paint coatings from surfaces - Google Patents

Abstract

The description relates to a process for removing coatings from surfaces by means of high-pressure water jets, whereby one of the following features is used alone or in combination: the surface is treated with an aqueous solution containing an organic non-corrosive swelling agent; the organic non-corrosive swelling agent is allowed to work on the surface to be treated for a certain time depending on the nature of the surface; and/or the surface is treated with a water jet at a temperature of > 20 DEG C and a pressure of 100 to 600 bar.

Description

Methods for cleaning surfaces using high pressure compressed water jets are widely known. These are used, for example, for cleaning facades, haircuts and bridges. Sandblasting is also widespread · The prerequisite for the application of the described methods is the specific strength of the surfaces to be machined. Therefore, they cannot be used for cleaning or machining surfaces which are essentially made of modern structural materials such as fiberglass or carbon fiber-reinforced plastics. made especially for use in the aerospace industry.

Removal of paint coatings from sensitive surfaces in lightweight construction, particularly in the field of aerospace engineering, is by prior art treating the surfaces with curing agents, such as organic chlorinated hydrocarbons, and then mechanically removing the pre-treated paint coating.

However, in addition to the paint layer that actually needs to be removed, other * deeper - layers would be damaged and fired. For example, in epoxy resin backbone aircraft construction, polyester-based pore fillers are applied, which again is applied to a so-called primary layer, such as polyurethane. Only then will this primer be overcoated · Depending on the type of aircraft, three or four coats of • topcoat will be applied.

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When using the aforementioned curing agents, the curing agents attack these layers. In addition, the use of chlorinated hydrocarbons should be considered from a health point of view, otherwise their use is environmentally unfavorable.

The present invention is based on the need for a process which only allows the topcoat to be removed from a surface constructed of several layers, and possibly also the option of removing the layers under the topcoat. In addition, the procedure must be environmentally friendly and not harmful to health.

In accordance with the present invention, this object is solved by the development of a method for removing paint coatings from surfaces using high-pressure water jets, comprising the following steps individually or in combination:

- treating the surface with an aqueous solution containing an organic, non-corrosive swelling agent,

- leaving the organic, non-corrosive swelling agent on the surface to be treated for a period of time appropriate to the condition of the surface, and / or

- treating the surface with a water jet at a temperature above 20 ° C and a pressure range of 100 to 600 bar.

In the process of the present invention, the term "water ··" is used in its widest sense. So, in the chemical sense, Water is both pure water, such as normal tap water, and again • V * · «

- 4 excavated splashes of water may be represented. · When using a non-corrosive organic swelling agent, the term water jet is understood to mean the radius of any relevant aqueous solution.

In a preferred embodiment of the process of the invention, water at elevated temperature, preferably JO-100 C *, is used. We select the water jet temperature according to the condition of the surfaces * so that the water jet temperature is easy to remove for a lacquer that is easy to remove, while higher temperature water should be used to remove other lacquer layers.

It has been found advantageous to use an aqueous non-corrosive swelling agent containing benzyl alcohol as an organic, non-corrosive swelling agent. Optionally, the aqueous non-corrosive swelling agent aqueous solution may also contain emulsifiers, surfactants, detergents, stabilizers, and the like.

It has been found to be advantageous to select an organic, non-corrosive swelling agent with an action time of from 120 minutes to 240 minutes when removing aged paint coatings. In the event that relatively fresh topcoat coatings are to be removed, a longer treatment time, preferably from 180 minutes to 100 minutes, at a given temperature is required. In case the topcoat layer has become brittle, it is still possible to apply the swelling agent. we can also cancel.

The higher the temperature of the high-pressure water jet, the less organic, non-volatile swell must be applied to the surface beforehand. The ideal temperature for organic, non-age • ·

- An expert will be able to determine the amount of 5 rosewood swabs that will be used with appropriate pre-emptive controls. · In addition, business considerations, such as minimizing costs that need to be adjusted according to the cost of the swelling agent and heated water, will be emphasized.

Without the use of an organic, non-corrosive swelling agent, it is generally found that the higher the jet temperature, the lower the jet pressure can be. This is particularly true in comparison with the treatment of aluminum surfaces, which are made of associated structural materials. While aluminum surfaces can be operated at just higher pressures, such as up to 6C0 bar, while maintaining temperatures in the range of about 80 ° C, especially in the case of composite materials, pressures ranging from 200 bar to 400 bar are preferred. still preferably at about 10 ° C.

Therefore, the process of the present invention is very suitable for treating thin-walled aluminum sheets and surfaces made of composite materials such as fiberglass reinforced plastics (GFK »Glasfaser Kunststoffe) and carbon fiber reinforced structural materials in aircraft and shipbuilding.

The swelling agent is applied by spraying or glazing on half of the surface to be lacquered by standard methods.

After a predetermined period of action of the swelling agent selected according to the state of the lacquer as described above, the topcoat loosened by the organic, non-corrosive swelling agent is removed by means of a water jet. The jet of water exits from a so-called gliding or rotating atomizer jet. The water used during this operation is, for example, normal tap water, optionally heated to the desired temperature and increased to a suitable pressure of 100 to 600 bar, preferably 200 to 500 bar. In addition, the jet of water may develop a downward force of about 15 kp.

In addition, a preferred embodiment of the process of the present invention is the use of antifouling nozzles.

In another particularly preferred embodiment of the process according to the invention, rotary dust auxiliary nozzles are used in which the water exits at a pressure of 200 to 500 bar and in which a 1 mm orifice has been found to be advantageous. Preferably, the jet of water is directed at an angle of 50 seconds from the surface to the surface to be lacquered at a distance of 50 to 150 mm. Preferably, the powder ace jets are moved at a rate of about 50 mm / sec.

The incident angle is kept flat and also this angle ^e is preferably from 30 to 60 ° in size. It has been found advantageous to direct the jet of water so that it hits the positive angle with respect to the cutting direction.

The water jet can also be produced with a large number of properly arranged nozzles. This allows a larger surface to be captured by the water jet.

Contains an organic, non-corrosive swelling agent

- 7 water solutions can be used to remove paint coatings from surfaces using a high pressure water jet process, especially for lightweight construction. · An aqueous solution containing preferably 40 * 80% benzyl alcohol is particularly recommended. Such solutions are commercially available and are manufactured by Türe © (Tureo 9064, 6088).

The process according to the invention thus enables the environmentally friendly and environmentally friendly removal of paint coatings from surfaces, particularly aluminum surfaces and associated structural materials. This process avoids the use of environmentally harmful pickling agents such as methylene chloride. If only a jet of elevated temperature is used, it is quite sufficient to remove the lacquer residues in the wastewater and recycle this process water to the process.

Using the process of the invention, the use of an organic, non-corrosive swelling agent presents various significant advantages over the prior art processes. By filtering off the peeled lacquer residue, the water is again fed to the high pressure pump. This allows multiple applications of water and thus further economic efficiency. The reuse of water is also beneficial from an environmental point of view. Choosing the right water jet temperature, appropriate to the specific cleaning problem, allows you to adjust the amount of organic, non-corrosive swelling agent as best as possible.

Claims (16)

Claims A method of removing paint coatings from surfaces using high-pressure water jets, comprising applying the following steps individually or in combination: • treating the surface with an aqueous solution containing an organic, non-corrosive swelling agent, - leaving the organic, non-corrosive swelling agent on the surface to be treated for a period of time appropriate to the condition of the surface, and / or - treating the surface with a water jet at a temperature above 20 ° C and a pressure range of 100 to 600 bar. 2. A method according to claim 1, wherein the surface is a thin-walled aluminum surface or a glass fiber or carbon fiber reinforced plastic surface. A process according to claim 1 and / or 2, characterized in that the aqueous solution of the organic non-corrosive swelling agent comprises benzyl alcohol. A process according to any one of claims 1 to 3 · - 9 characterized in that the organic, non-corrosive aqueous solution contains from 40 to 80% by volume of benzyl alcohol as swelling vein » The process according to any one of claims 1 to 4, characterized in that the aqueous solution of the organic non-corrosive swelling agent comprises, in addition to the swelling agent, excipients, preferably emulsifying agents, surfactants, detergents and the like. The process according to any one of claims 1 to 5, characterized in that the aqueous solution of the organic non-corrosive swelling agent has an action time of 120 minutes to 240 minutes when removing old paint coatings, otherwise it is between 180 minutes and 300 minutes. Process according to any one of claims 1 to 6, characterized in that the temperature of the high pressure water jet is maintained between 30 ° C and 100 ° C. A method according to any one of claims 1 to 7, characterized in that the water jet exits the so-called flat or rotary nozzles bdL. Method according to any one of claims 1 to 8, characterized in that a sliding powder ace is used. Method according to any one of claims 1 to 9, characterized in that the water jet has a kickback force of 15 kp. A method according to any one of claims 1 to 10, characterized in that the water jet is inclined at an angle of less than 90 ° to the surface. The method of claim 11, wherein the angle is between 30 ° and 6 °. The method according to any one of claims 1 to 10, characterized in that the jet of water is inclined at a positive angle when viewed from the cutting direction. A process according to any one of claims 1 to 13, characterized in that the water jet is produced by a large number of nozzles. ^ 15 ·) use of a non-corrosive swelling agent to remove paint coatings using a high pressure water jet. 16. Use of an aqueous solution according to claim 15, comprising benzyl alcohol.