HK1115348A - Method and apparatus for removing paint and sealant - Google Patents

Description

Apparatus and method for removing paint and sealant

Technical Field

The present invention relates generally to the removal of paints and sealants, and more particularly to a non-destructive and effective apparatus and method for such removal.

Background

Several methods of removing paint are known and in general these can be divided into three broad categories: mechanical, thermal and chemical methods.

Mechanical friction processes are well known in the art. Scraping is typically accomplished with either a putty knife or a paint scraper, or both. The putty knife has a width in the range of one inch to six inches and has a beveled edge. In use, the putty knife is pushed under the paint and maneuvered from a loose paint area to an edge where the paint is still firmly adhered. Common paint scrapers are 1-5/16, 2-1/2, and 3-1/2 inches wide and have replaceable blades. In addition, the forming blade can be specially manufactured for special purposes. The paint scraper is used by pushing it, and operates by raking away the damaged paint area. The doctor blade may be made of steel, aluminum, wood, Mycarta and nylon, and for reasons of appearance or construction it is desirable to select a material softer than the substrate to be doctored to avoid damage.

Putty and paint scrapers, particularly those having a hooked edge, must be used with care to avoid "scratching". For example, when using a metal scraper to remove paint or sealant on the surface of an aircraft, scratches are considered to be a significant problem causing crazes and cracks that can eventually develop into large cracks and threaten the structural integrity of the aircraft. The preferred methods of using the doctor blades on board an aircraft are those described in aircraft structural repair guidelines (SRM) or American national Bureau of civil aviation Advisory advisories (FAA Advisory circuits), AC65-16A and AC 43.205. The following government documents document and discuss solutions to the problem of fatigue cracking caused by scratch scratches: federal aviation gazette FSAW 03-10B (revised) published 3/31/2004, "boeing 737 aircraft fuselage skin 'scratch' damage"; transport canadian flying resistance bulletin (the transport Canada air engineering Notice) B071, 11/month 1-3/2004 "method for removing paint and sealant".

Other mechanical methods of removing paint include sanding, shot peening, water peening, plastic media peening, and other similar methods. All these methods are characterized by modifying the surface subjected to surface friction, and in addition these methods tend to be relatively slow and labor intensive.

Methods of applying heat, such as hot plates and heat guns, are also well known. The application range of the thermal method is narrow.

Finally, the paint can be chemically removed. Solvent-based strippers typically have a formulation that includes a combination of the following organic solvents: such as methylene chloride, isopropanol, toluene, xylene, and methanol. Such as thickeners incorporating methylcellulose and various additives such as paraffin wax to prevent volatile solvents from evaporating before they have time to soak through several layers of paint. Some solvent-based strippers are very thin and therefore not suitable for use on vertical surfaces, while others, known as "semi-pastes", are formulated for use on the inside of vertical or horizontal surfaces. More recently, paint removers have been formulated with a mixture of water and benzyl alcohol.

Chemical paint removers present several problems in use. Especially paint removers containing methylene chloride, are subject to health and environmental limitations. Because they are sprayed onto surfaces to function, applicator personnel must wear full body protective gear while using the material, and the Volatile Organic Compounds (VOCs) of the sprayed material are closely monitored by the united states clean air act. Finally, after the scraping operation with chemicals, large amounts of liquid/solid waste are produced and must be disposed of safely.

Accordingly, there is a need for a paint removal system that addresses several of the above-mentioned problems.

Disclosure of Invention

The present invention provides an inexpensive and minimally destructive apparatus and method for removing paint and other coatings from a surface.

In one form thereof, the present invention provides an apparatus for removing surface material. The device comprises a tape having a masking material and a release agent, the masking material being adapted to adhere to the surface, wherein the masking material and the release agent can be applied in a single step.

In a preferred embodiment, the device includes a matrix filled with a stripper and a bladder containing the stripper. The matrix and the bladder are both centrally disposed with respect to the longitudinal axis of the tape, and the covering material is disposed on lateral sides of the tape. The backing material is removably attached to the tape.

In another preferred embodiment, the device comprises an elongated tape having masking materials disposed along lateral sides thereof and a release agent disposed between the masking materials. The tape is wound on a roll and includes a removable liner.

In another form thereof, the invention is directed to a method of removing material from a surface. The method comprises the following steps: masking a portion of the surface with a masking material to protect the portion of the surface from the stripper; and applying a release agent on the uncovered portion of the surface. These steps are performed substantially simultaneously.

One advantage of the present invention is that time is saved. Unlike two separate steps, the release agent and the masking material may be applied simultaneously in a single step. Use of the present invention allows aircraft operators to perform removal steps within their service hangers during other routine inspections, rather than requiring the aircraft to be sent to a dedicated paint and sealant removal facility. It is envisioned that the present invention is provided to the user as a kit for any type of aircraft requiring the inspection of scratches. Current practice is to conceal the aircraft as if the paint and sealant were completely removed. The present invention eliminates labor intensive steps in the process.

Another advantage of the present invention is that it allows for the use of less stripper because the stripper material, which is typically volatile, is capped, greatly reducing evaporation. Less stripping agent is used, the material cost is saved, and the quantity of garbage is reduced, so that the treatment cost is reduced. The effectiveness of the stripper is increased because the solvent that penetrates into the paint remains near the surface within the channels and does not evaporate into the air. In addition to improved effectiveness, reduced evaporation means that the contribution of the stripper to the overall VOC production of the plant is reduced, thereby providing the advantage of greatly preventing pollution.

From the same point of view of preventing contamination, the invention will significantly shorten the "clean-up" phase in the doctoring operation, in which a considerable amount of solvent and contaminated water will be produced. Since the paint and sealant adhere to the glass fiber mesh substrate after the scraping process, all sources of contamination, i.e., stripper, paint and sealant, are confined to an object that can be treated accordingly.

Another advantage of the present invention is that because only the stripper and mesh block are in contact with the surface to be inspected, no residue of adhesive is left that could interfere with the inspection procedure.

Drawings

The above-mentioned and other advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a perspective view, partially in section, of an embodiment of a material removal device of the present invention;

FIG. 1A is an enlarged perspective view of a portion of the device shown in FIG. 1;

FIG. 2 is a partial perspective view of the device of FIG. 1 applied to a lap joint;

FIG. 3 is a perspective view, partially broken away, of an alternative embodiment of the invention;

FIG. 4 is a partial perspective view of an alternative embodiment of the present invention;

FIG. 5 is a cross-sectional view of an alternative embodiment of the present invention;

FIG. 6 is a cross-sectional view of an alternative embodiment of the present invention; and

fig. 7 is a partially enlarged perspective view in partial cross-section according to another embodiment of the present invention.

Like reference symbols in the various drawings indicate like elements.

Detailed Description

The embodiments of the present invention that are set forth below are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may understand and appreciate the principles and practices of the present invention.

Referring now to fig. 1 and 1A, an apparatus 10 for removing surface material is provided with a tape 12, the tape 12 comprising a supply of masking material as a strip 14. A stripper portion or matrix 16 is centrally disposed in the tape 12 and between the strips 14. The debonder portion 16 also includes a layer of fibrous material 18. Adjacent to and in contact with the fibrous material layer 18 is a bladder 20, which in the illustrated embodiment includes a liquid stripper that impregnates or saturates the fibrous material layer 18 with a liquid chemical stripper (not shown) during use of the device 10 to be described below. The pouch 20 is preferably configured to rupture upon application of a force thereto, such that liquid within the pouch 20 saturates the fibrous layer 18, as will be described below. Neoprene is one suitable material for bladder 20. Rectangular shell 22 forms a channel and houses layer of fibrous material 18 and bladder 20 therein. The housing 22 is preferably made of a quasi-rigid material such as mylar (mylar ®). Optional beads 24 connect the cover material 14 to the housing 22. The bead 24 may be made of rubber or other suitable polymer. The removable liner 26 is shown covering the tape 12. The tape 12 is wound around a roller 28.

Referring to FIG. 1A, the masking material 14 is preferably a conventional masking tape having an adhesive 30 applied to one side thereof. One Tape suitable for use with the device 10 is an Aluminum Tape conforming to the requirements of MIL-T-23397B, having a one inch width, available from 3M Corporation, Grade 417Aluminum Foil Tape, 900Bush Avenue, StPaul Minnesota, 55133, information below. The adhesive provided on the tape should adhere sufficiently to the surface being peeled off to form a liquid-tight seal with that surface, thus making the weld bead 24 optional. In embodiments employing the weld beads 24, the cover material 14 is joined to the weld beads 24 by heat welding, sonic welding, adhesives, or other suitable fastening means.

Housing 22 may also be connected to weld bead 24 by any suitable fastening means. As previously mentioned, the housing 22 is relatively rigid for reasons described below. Suitable materials for housing 22 meet the requirements of MIL-P-22270, available from Dupont Discovery Films, 1Discovery Drive, Hopewell Virginia, 23860. The approximate desired thickness of the shell 22 is 10 mils (mil). An alternative packaging material is an oxygen barrier bag material consisting of a polyester resin/aluminum sandwich material, commonly referred to as a "mylar" bag. To improve puncture resistance, nylon may be substituted for the polyester. These products are produced by IMPAK corporation, 2460EAST57^thSt, Los Angeles, CA 90058, and these products are available therefrom.

Also, although shown in the embodiment as rectangular, the housing 22 may be curved or rounded. The housing 22 is preferably non-porous so that the stripper liquid contained therein cannot leak out or evaporate.

The pouch 20 may be a tube or oval that is easily installed into the housing. The tube containing the stripper is filled using standard liquid filling techniques and placed in a semi-rigid matrix or housing 22. Preferably, the bladder has the same cross-sectional dimensions as the housing and will fit snugly against the housing 22. Once the bladder 20 is inserted into the shell, the fibrous matrix 18 for absorbing the debonding agent is packed into the shell and bonded to the shell with a chemical resistant epoxy adhesive (chemical resistant epoxy adhesive). Polyethylene (Tygon)^®) An extruded hose is suitable for making the pouch 20 and is available from Prince Rubber and Plastics, 137Arthur Street, BuffaloNY 14207.

The liquid filling pouch 20 can be any of a variety of commercially available release agents, depending on the particular paint, sealant or coating to be removed with the release agent. To remove the coverlay on commercial aircraft, the release agent should be able to remove the polyurethane topcoat, epoxy primer, and conventional polysulfide sealants, such as those that meet the requirements of MIL-S-8802. One such stripper is Eldorado Solutions, PR-3133, Eldorado Solutions, Carmel Indiana.

The fibrous material suitable for the layer of fibrous material 18 can be any material that is inert to the debonding agent and that readily diffuses the debonding agent material upon contact uniformly over the contacted surfaces. The term "inert" means that the fibrous material is substantially chemically inert with the stripper composition and is capable of maintaining mechanical integrity for a period of time, at least for the life of the device 10. Examples of suitable materials for the fibrous material layer 18 include polymers such as polypropylene and polyethylene; woven or non-woven fabrics such as felt, cotton and wool; such as fiberglass of fiberglass. Those skilled in the art will recognize that many materials are suitable for fibrous material layer 18.

The liner 30 may be polyvinyl chloride (PVC), nylon, paper with a metallized inner layer material to prevent chemical migration, mylar with an aluminized liner, or any other material having the following characteristics: a channel for inserting the bladder and the fibrous matrix can be formed; the scraper is rigid but still can be operated by nylon hands to fracture; chemically resists the migration of the release agent for a sufficient period of time (e.g., not less than 24 hours); and is compatible with adhesives on other materials used to make the device 10, such as aluminum tape. One such preferred material is an extruded polyvinyl chloride liner. The ready availability of these extrusions for mounting the bladder and matrix in the pad and the ability to form complex internal geometries allows the selection of the required pad. One such manufacturer of the liner 30 is Fukuvi USA, 7631 Progress Court, Huber Heights, OH 45242.

Referring now to fig. 2, in use the tape 12 is applied to a surface such as an aircraft skin 34, in particular to the lap joint 36. Most aircraft have a number of lap joints, such as joint 36 that includes rivets 38 to secure the lap joints. Sealants are commonly used on joints, as are paints. In order to check the integrity of the lap joint after several years or decades of aircraft manufacture, the paint and sealant must first be scraped from the joint. However, as mentioned above, commonly used metal scrapers are prone to scratching or "scuffing" the aircraft skin, which may eventually cause large cracks.

The tape 12 is centered over the lap joint that is desired to be stripped and then applied to the housing 34 in the same manner as a conventional tape. After the tape is applied, pressure is applied to the shell 22 in the direction indicated by arrow 40, which ruptures the bladder, which in turn causes the liquid stripper to saturate the fibrous layer 18. The fibrous layer is then dosed with the stripper liquid, i.e. spread evenly over the surface of the shell to be scraped off. The bead 24 prevents lateral diffusion of the stripper liquid, thus defining a boundary or perimeter beyond which the stripper cannot extend.

After the desired time has elapsed, the strap 12 is removed from the aircraft skin 34. Ideally, the release agent removes the paint and sealant from the aircraft skin and adheres to, but remains intact with, the fiber layer 18. In this case, the paint and sealant are removed as a separate layer with the tape 12. In many cases, however, this is not possible, requiring manual wiping and perhaps some slight scraping after removal of the tape 12 to remove paint and/or sealant residue. In any event, those skilled in the art should now readily appreciate that the masking material and the release agent are applied substantially simultaneously in a single step.

Referring now to FIG. 3, an alternative embodiment of an apparatus 100 is shown that includes a liner 102, a looped fibrous layer 104, and a cover material 106 surrounding the fibrous layer. The apparatus 100 is used for scraping off stains on the surface of a site to be treated. In the same manner as described above with reference to device 10, device 100 is simply applied to the spot to be scraped.

Fig. 4 shows another embodiment in which apparatus 200 includes evenly spaced doctoring areas 202 for use in applications in which the areas to be doctored are also evenly spaced. The interior side (not shown) of the device 200 includes a liquid scraping material, preferably contained within a pouch and/or fibrous material, and also includes a removable liner layer as described above.

In fig. 5, an embodiment is shown in which the apparatus 300 includes a tape 302, a backing material 304, and a liquid stripper-impregnated fibrous matrix 306 sandwiched therebetween. The optional bladder is not provided in this embodiment. In effect, the backing material 304 and the band 302 form a liquid-tight seal 308 that retains the doctored material within the fibrous matrix 306 until the backing material is removed and the device 300 is applied to the surface to be doctored.

Fig. 6 illustrates an embodiment in which the device 400 includes a band 402 and a housing 404, both of which are coupled to a weld bead 406. The gasket material 408 is hermetically sealed to the band 402. The pouch 401 is contained within the housing 404 and contains a liquid stripper. Device 400 is used in the same manner as device 10, except that there is no fibrous matrix in device 400. The bead 406 helps to prevent lateral spreading of the liquid stripper outside the area to be scraped off.

In another embodiment shown in FIG. 7, the device comprises a release agent impregnated polyethylene (Tygon)^®) The pockets 20 are adjacent the glass fiber mat 18. The bladder 20 is in turn surrounded by a PVC channel or shell 22, said shell 22 having been fixed to the aluminium strip 14, the aluminium strip 14 being flanked by a further layer of tape 14 a. That is, unlike the embodiment of fig. 1 having a single tape 14, this embodiment includes two layers of tapes 14 and 14a laminated together. A removable paper liner (not shown) protects the composition of the PVC channel 22 from degradation. The adhesive pull strength of the upper layer 14a of tape is about half that of the tape 14 which is adhered to the surface to be treated, thus allowing the operator to remove the passageway 22, stripper bladder 20 and mesh matrix 18 while leaving the outer covering material 14 adhered to the surface. Because chemical removal of paint and sealant may not be complete, this embodiment allows the user to do a small "touch up" job and perform the above-described inspection before removing layer 14.

Although the foregoing has disclosed preferred embodiments incorporating the principles of the present invention, the present invention is not limited to the disclosed embodiments. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

Claims (19)

1. A device for removing a substance from a surface comprising a tape having a masking material and a release agent, the masking material being adapted to adhere to the surface, wherein the masking material and release agent can be applied in a single step.

2. The device of claim 1, further comprising a matrix containing a debonding agent.

3. The device of claim 2, wherein the matrix comprises a pouch containing a stripper.

4. The apparatus of claim 2, wherein the matrix comprises a bladder and a fiber layer, the bladder containing the stripper, the matrix being disposed centrally of the tape relative to a longitudinal axis of the tape, the masking material being disposed on lateral sides of the tape.

5. The apparatus of claim 1, wherein the band comprises a backing material removably attached to the band.

6. The device of claim 1, wherein the masking material surrounds the release agent and defines a perimeter to which the release agent is applied.

7. The device of claim 1, wherein the masking material comprises an adhesive.

8. The device of claim 1, wherein the tape is elongated, masking material is placed along lateral sides of the tape, and a release agent is placed between the masking material.

9. The apparatus of claim 8, wherein the belt is wound on a roller.

10. The device of claim 8, further comprising a removable liner disposed on one side of the band.

11. A method of removing a substance from a surface comprising the steps of:

(a) masking a portion of the surface with a masking material to protect the portion of the surface from the stripper; and

(b) applying a release agent on an uncovered portion of the surface;

wherein steps (a) and (b) are performed substantially simultaneously.

12. The method of claim 11, further comprising removing a masking material and removing at least a portion of the substance with the masking material.

13. The method of claim 11, wherein the masking material and release agent are provided in roll form.

14. The method of claim 13, wherein the web comprises an elongated tape having masking material disposed on lateral sides thereof and a release agent disposed between the masking material.

15. The method of claim 13, wherein the web further comprises a removable liner.

16. The device of claim 1, wherein the covering material comprises two covering layers removably attached together.

17. The method of claim 11, wherein the masking material comprises two masking layers removably attached together, the method further comprising removing one of the masking layers after step (b) while leaving the one masking layer attached to the surface.

18. The method of claim 11, wherein the surface comprises an aircraft surface.

19. The method of claim 11, wherein the surface comprises a lap joint.