Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
  • B05D7/14—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D1/00—Processes for applying liquids or other fluent materials
  • B05D1/62—Plasma-deposition of organic layers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
  • B05D3/14—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by electrical means
  • B05D3/141—Plasma treatment
  • B05D3/142—Pretreatment
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
  • B05D3/14—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by electrical means
  • B05D3/141—Plasma treatment
  • B05D3/145—After-treatment
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
  • B05D7/50—Multilayers
  • B05D7/52—Two layers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
  • B05D7/50—Multilayers
  • B05D7/52—Two layers
  • B05D7/53—Base coat plus clear coat type

Definitions

• the present application relates generally toward a method of coating a cast alloy wheel for providing improved durability. More specifically, the present application relates toward a method of treating a cast alloy wheel with plasma as part of a coating process for providing improved durability.
• the alloy wheel is machined to provide a smooth surface having a desired configuration.
• the entire wheel is subject to a pre-treatment including liquid cleaning and the addition of a liquid conversion coating to provide corrosion resistance and improved paint adhesion.
• the wheel is painted with a powder primer and liquid color coat after which, the face of the wheel is sometimes again machined to expose a bright machined surface to achieve a desired aesthetic affect.
• the machined portion of the wheel is once again treated with a liquid conversion coating and painted with a powder or liquid clear coat to provide a two-toned appearance where the face of the wheel exhibits a bright machined surface and the remainder of the three-dimensional contours of the wheel exhibits the color coating.
• a method of coating an alloy object includes providing a plasma assembly for exposing an object ionized plasma.
• An energy state of the surface of the object is increased by the ionized plasma activating the surface of the object
• a silicon based compound is injected into the ionized plasma for coating the surface of the object with silicon compound while the surface of the object is disposed at a raised energy state.
• the raised energy state of surface of the object is lowered toward a ground state for allowing the silicon based compound to react with the surface onto which it is applied forming a new crossl inked compound.
• the energy slate of the surface of the object is again raised by exposure to the ionized plasma after the silicon compound has crosslinked.
• a first polymeric coating is subsequently applied to the surface over the silicon compound.
• plasma is optionally emitted onto a first polymeric coating prior to applying a second polymeric coating to raise the energy state of the fust polymeric coating prior to applying the second polymeric coating.
• first polymeric coating Subjecting the first polymeric coating to the plasma treatment has proven to enhance adhesion between coating layers. It is believed that the increased energy state of the first coating improves bonding and intra coat adhesion between the first and the second polymeric coating.
• multi-layer coating adhesion and durability improvements arc achievable.
• Crosslinking of the conversion coating is desirable for improved durability. It has also been discovered that raising the energy state of the conversion coating after crosslinking facilitates bonding of the polymer coating to the silicon based conversion coating further improving durability performance.
• the inventive method of the present application has provided enhanced durability qualities that wasn't previously achievable of the prior art coating process all while reducing the use of hazardous chemicals in creating conventional conversion coating. Prior to the performance testing done on a wheel subjected to the process of the present application, it was believed that treating an alloy surface with a conventional conversion coating provided the best possible durability when the wheel surface is painted with a polymeric coating.
• a gravelometer test was performed per ASTM D3170 standards on a wheel coated by the method of the present invention and a wheel coated by the conventional method. Although the coating was marred, the wheel coated using the method of the present invention showed no chipping of the coating layers after being subjected to the gravelometer test and having an ASTM rating of A, or the highest rating indicating improved adhesion.
• the wheel having the conventional coating showed a significant number of coating chips in the range of 3-6 mm.
• FIG. 1 shows a cross-sectional view of a wheel and nozzle element of the present invention
• FIG. 2 shows a cross-sectional view of a wheel and an alternative embodiment of the nozzle element of die present invention
• FIG. 3 shows flow chart of one embodiment of the method of the present invention
• FIG. 4 shows a flow chart of a further embodiment of the method of the present invention.
• FIG. 5 shows a flow chart of a still further embodiment of the method of the present invention.
• FIG. 6 shows a flow chart of a still further embodiment of the method of the present invention.
• the method of coating an aluminum wheel of the present invention provides a streamlined process over that of the prior art while simultaneously enhancing durability of the wheel.
• FIG. 1 a cross-section of an aluminum wheel is generally shown at
• the wheel 10 is formed via a conventional forming method and includes a machined face
• the wheel 10 defines a wheel axis a around which the wheel rotates, as is well known to those of skill in the art
• the wheel 10 also includes three-dimensional configuration having recessed surfaces 14 that define sides of the wheel spokes and visible portions of a wheel rim 17.
• An edge 19 is disposed between the machined face 12 and the recessed surfaces 14.
• nozzle element 21 includes plasma nozzle 23 that is mounted on an articulating arm 25, such as, for example, a robot arm.
• the plasma nozzle 23 projects a plasma jet 27 in an atmospheric environment as set forth in U.S. Pat No.
• the nozzle 23 is provided by PlasmaTrcat GmbH, However, the other equivalent nozzles 23 capable of providing an atmospheric plasma jet may also be used. In addition, other methods of exposing the wheel
• a gas line 29 feeds a reactant fluid into the nozzle 23 when desired.
• siloxane based compounds such as, for example hcxamcthyldisiloxane, or other reactant will suffice as will become more evident herein below.
• other methods of plasma treatment are within the scope of the invention including. but not limited to vacuum and gas assisted applications.
• the articulating arm 25 moves the nozzle 23 laterally in a generally parallel direction relative to the wheel axis a and radially inwardly and outwardly relative to the wheel 10.
• the wheel 10 rotates around axis a while the nozzle 21 projects the plasma jet 27 toward the wheel 10.
• the articulating arm moves the nozzle 21 in a radial direction so that the plasma jet 27 contacts the entire face 12 and edge 19 of the wheel.
• the nozzle 23 continues to project the plasma jet 27 into open spaces 31 between spokes 33 and lug apertures 13 of the wheel 10 so that at least a portion of the recessed surfaces 14 are subject to plasma treatment.
• FIG. 2 An alternative embodiment is shown in FIG. 2 where two nozzle elements 21 are included.
• Each nozzle element 21 includes a nozzle 23 mounted on an articulating arm
• the two nozzle elements 21 arc believed to reduce the cycle time for plasma treatment by half.
• Each nozzle 21 moves in a lateral direction parallel to the axis a and in a radial direction related to the wheel.
• the wheel moves only 180° while the nozzles project plasma jet 27 at a desired location.
• the wheel can remain in a stationary position while each articulating arm 25 moves each nozzle 23 around the wheel 10, including projecting plasma directly at the recessed surfaces 14. It is further believed that more than two nozzle elements 21 can be selected to further reduce cycle time.
• multiple nozzles extend radially outwardly from the axis a so that the wheel need only turn one rotation of 360° to complete the plasma process.
• a plurality of nozzles 29 are configured as an X or a cross shape extending radially outwardly from the axis a so that the wheel need only turn 90° for full plasma coverage or not at all while the articulating arms 25 move the nozzles 29 around the wheel 10.
• FIG. 3 a flowchart of a first embodiment is generally shown at 16 where each numbered box represents a different Step of the processing and coating of the wheel 10.
• the wheel 10 is first formed to a geometrically desirable configuration as identified at Step 18.
• the wheel 10 is subject to conventional cleaning and pretreatment as identified at Step 20 where acidic cleaners, such as. for example, a phosphoric based cleaner, clean the surface of the wheel and a zirconium titanium molecular etch is performed to form a zirconium based conversion coating to prepare the entire surface of the wheel for applying a paint coating.
• acidic cleaners such as. for example, a phosphoric based cleaner
• a zirconium titanium molecular etch is performed to form a zirconium based conversion coating to prepare the entire surface of the wheel for applying a paint coating.
• a base coat is applied to the entire wheel surface providing a primer surface as identified at Step 22.
• a color coating is applied to, at least, the three-dimensional surface 14 of the wheel 10
• the color coating at Step 24 sometimes referred to as a base coat, includes pigments for color and metallic flakes to add visual depth to the three-dimensional surface 14 to further enhance the esthetics of the wheel 10.
• the face 12 of the wheel 10 is machined on a lathe to provide a generally planar surface that has a bright machined appearance as identified at Step 26. It should be understood by those of ordinary skill in the art that after each paint application step 20, 24, 32 the paint is cured in a paint bake oven.
• the face 12 of the wheel 10 After the machining Step 26 is performed on the face 12 of the wheel 10, which is now a bare, smooth machined aluminum, the face 12 subject to a plasma pretreatment as identified at Step 28.
• the plasma pretreatment Step 28 includes washing 28A and rinsing 28B the wheel 10 to provide a clean surface to the face 12 by removing alloy grinds, dust and die release agents.
• the face 12 of the wheel is subject to a plasma treatment having an atmospheric plasma jet 27 for providing plasma cleaning to the face 12 of the wheel 10.
• a plasma nozzle 23 is shown providing a plasma jet 27 onto the bright machined surface comprising the face 12 of the wheel 10.
• the plasma jet 27 performs the plasma cleaning step 28C during which remaining particulate matter is removed from the alloy surface.
• the plasma also ionizes the alloy surface causing an increase in the energy state of the alloys surface.
• alloy oxides such as, for example, aluminum oxide are formed on the surface after being subject to the plasma cleaning step 28C.
• the wheel 10 is pivoted on an axis a (FIG. 3) while the nozzle 29 moves toward the axis a (FIGS. 1 and 2) of the wheel 10 from proximate the rim 17 toward the axis a for providing a plasma treatment 28C (FIG. 4) to the bright machined face
• the plasma jet 27 used in Step 28C includes a spray pattern providing a rapid plasma cleaning to the bright machined face 12 of the wheel
• a plasma conversion process is performed where a hcxamcthyldisiloxane or equivalent reactant is injected into the plasma jet 31 providing for an aluminum siloxane molecular structure or other alloy siloxanc structure, to form onto the bright machined face 12 of the wheel 10 as will be explained in further detail herein below.
• the plasma jet 31 diameter is about
• Step 28B set forth above may also be used. Furthermore, it is desirable to space the nozzle 23 for both Steps 28C and 28D at an effective distance from the bright machined face 12 of the wheel 10. To the extent the bright machined free 12 of the wheel 10 is not substantially planar, the nozzle 23 moves toward the face 12 of the wheel 10 to maintain the effective distance from the lace 12, as set forth above. As further set forth above, the edge 19 is also subject to the plasma jet 27.
• a plasma curing Step 28E is performed to prepare the wheel for a clear coat paint application identified at Step 32.
• the energy level of the conversion coating is raised at Step 28F by again projecting plasma with the plasma jet 27 toward the surface of the wheel. As set forth above, it is believed that reactivating, or increasing the energy level of the conversion coating improves the adhesion of the clear coat to the conversion coating improving performance.
• the clear coat is either a powder or liquid depending upon the needs and performance rea auirements of a particular wheel. After the clear coat has cured, the wheel is ready for packaging and shipping as shown in Step 34.
• FIG. 4 An alternate embodiment is shown in FIG. 4.
• the wheel is formed at Step 36 as set forth above.
• the entire wheel is subject to a color pretreatment identified at Step 38.
• the entire wheel is washed and rinsed as identified in Steps 38A and 38B to clean contaminants from casting off the surface of the wheel 10.
• the entire wheel 10 is treated to atmospheric plasma cleaning as identified as Step 38C.
• the wheel is placed into a vacuum chamber where a plasma gas performs plasma cleaning on the entire surface of the wheel 10.
• a plasma or plasma conversion Step 38D is performed.
• the chamber is again maintained in a vacuum and a siloxane gas, or equivalent reactant, is injected prior to plasma treating the entire wheel. Therefore, the entire wheel includes a siloxanc aluminum, or equivalent siloxanc alloy, etched surface.
• the wheel 10 is subject to a plasma curing
• Step 38E of the conversion coating to accelerate crosslinking or curing of the conversion coating is again reactivated by performing the second plasma activation step 38 F completing the plasma pretreatment Step 38 of the wheel 10.
• a base coat or primer application follows the plasma pretreatment Step 38 as is identified at Step 40. Subsequent to the base coat application Step
• a color application Step 42 is performed in a similar manner as set forth above.
• the face 12 of the wheel 10 is subject to a machining Step 44 that occurs in a similar manner as set forth above to expose a bright machined face 12. After the machining
• Step 44 a plasma pretreatment Step 46 occurs, which is similar to the clear pretreatment Step
• the bright machined face 12 of the wheel 10 in this embodiment receives an atmospheric plasma cleaning and plasma conversion by way of plasma jet 27 prior to being subject to a clear coat application Step 48 in a similar manner as set forth in step 38.
• alternative plasma exposure is also included within the scope Step 46.
• the clear coat application takes the form of a powder dear coat or a liquid clear coat
• the paint is cured in a paint bake oven. Once the clear coat is cured, the wheel is packaged for shipping to the customer.
• Step is a forming Step 47 after which the wheel 10 is subject to a color pretreatment Step 49.
• the color pretreatment Step 49 is either a conventional color pretreatment where the wheel is subject to a liquid cleaning and a liquid conversion, or a plasma clean and plasma conversion as desired.
• the wheel is subject to a base coat application Step 50 includes providing a primer, in particular, to the three-dimensional surfaces 14 of the wheel 10. After the base coat application Step 50, an inter-coat conversion
• Step 52 is performed subjecting the base coat disposed on the wheel 10 to a plasma, plasma cleaning 52A as set forth above, followed by a plasma conversion Step 52A of plasma having a siloxane, such as, for example hexamethyldisoloxane or other equivalent reactant disposed in the plasma jet to alter the surface chemical composition of the base coat applied during the base coat application Step 50 forming a siloxane polymer
• a siloxane such as, for example hexamethyldisoloxane or other equivalent reactant disposed in the plasma jet to alter the surface chemical composition of the base coat applied during the base coat application Step 50 forming a siloxane polymer
• the temperature of the of the wheel is raised in an oven in curing step 52C.
• the surface of the wheel is subject to a second activation step
• the wheel receives a color coating, in particular on the three-dimensional surfaces 14 via the color application Step 54.
• the face 12 of the wheel 10 is next subject to a machining Step 56 to provide a bright machined surface that is next subject to a dear pre treatment Step 58 being either a conventional liquid pretreatment or the plasma cleaning and plasma conversion treatment using the plasma jet 27 or other plasma exposure as set forth above.
• a clear pretreatment Step 58 is completed a clear coat application Step 60 provides an aesthetically pleasing finish to the entire wheel 10.
• the paint is cured in a paint bake oven. Once complete, the wheel 10 is packaged for shipment to the customer.
• Step 62 the flexibility of the subject invention is shown where alternative and redundant plasma treatment steps may be applied to the wheel 10 making use of the plasma clean and plasma conversion steps of the present invention.
• the wheel is formed Step 62, and is subsequently subject to the color pretreatment
• Step 64 which makes use of a liquid cleaning and a liquid conversion coating.
• Step 66 a primer is applied to the wheel 10.
• the wheel is subject to an inter- coat conversion Step 68 that is performed in the same manner as set forth at the embodiment above making use of plasma cleaning 68A and plasma conversion Step 68B of the primer applied at the base coat application Step 66.
• the wheel 10 in one embodiment, is heated to facilitate curing or crosslinking of the siloxane conversion coating in Step 68C and the then the surface of the wheel is subject to a second plasma activation step 68D to raise the energy level of the conversion coating.
• Alternative embodiments include infrared light curing, ultraviolet light curing, chemical curing and even plasma curing of the siloxane conversion coating.
• the curing includes the formation siloxane molecules, siloxane alloys and siloxane polymers when the siloxane conversion coating is applied over a polymer coating.
• a color application Step 70 is performed, whereby a color coating is applied, at least to the three-dimensional surfaces 14 of the wheel 10.
• the face 12 of the wheel 10 is machined on a lathe during the machining Step 72 to provide a bright machined surface on the face 12 of the wheel 10.
• the clear pretreatment Step 74 occurs where the wheel 10 is first washed at the washing Step 74A and rinsed at the rinsing
• Step 74B Following the rinsing Step 74B, the plasma clean Step 74 C and the plasma conversion Step 74D making use of ambient plasma jet 27 including siloxanc, or equivalent reactant, respectively, as set forth above, occurs. Subsequent to the plasma conversion Step
• the wheel is dried and preheated, or otherwise cured (as explained above), for energy reduction in step 74E followed by a reactivation step 74F as set forth above.
• the clear coat application Step 76 occurs to apply clear coat to the entire wheel.
• Step 76 the wheel 10 is packaged and shipped to the customer.
• Step not only provides a plasma cleaning, to at least the bright machined surface 12 of the wheel 10, and a plasma conversion using a siloxane or similar reactive compound is also subjects the transition edge 19 to the same pretreatment.
• the durability performance of the wheel when subject to chip testing and corrosion testing showed unexpected and enhanced results.
• Various application methods of the plasma cleaning and plasma conversion Steps contemplated by the inventors include a 2D turning profile where the wheel 10 is pivoted on its axis a along a three-dimensional CMC surface profile whereby the plasma jet 27 follows the profile of the wheel by way of articulating aim 25, and plasma treatment of the entire wheel in a low vacuum environment at both ambient and siloxanc enhanced Steps.
• alloy oxide for example, aluminum oxide
• the surface 12 of the object being painted in this case, the wheel 10.
• the surface includes an elevated energy from its ground state and the aluminum oxide is unstable.
• a plasma coating is applied during the plasma conversion step 28d, 38d, 74d.
• the plasma conversion step 28d, 38d, 74d is performed by way of injecting the plasma jet 27 with vaporized hexamethyldisiloxane.
• the vaporized hexamethyldisoloxane Upon entry into the plasma jet, the vaporized hexamethyldisoloxane is broken down to its basic monomers forming excited monomers of silicon dioxide.
• the silicon dioxide bonds and reacts with the alloy oxide forming a coating have a thin film of silicon alloy.
• the Plasma/preheat step 28c, 38c has proven effective in accelerating the crosslinking while also accelerating the reduction in surface energy. Test results have shown that twenty minute dwell time at 350°F is sufficient. In the case application of intcrcoat conversion coating 52,
• the excited siloxanc monomers react with the surface of the base coat enhancing adhesion to the clear coat applied over the intcrcoat conversion coating.
• the ground state surface energy prevents good bonding of the clear coat to the conversion coating and results in substantive paint defects. It has been determined an additional plasma treatment after the preheat surface energy reduction step again raises the surface energy of the plasma coating without destroying the molecular bonds between the monomers and the alloy oxides substantially improving the clear coat adhesion.
• the clear coat that has been tested is an epoxy acrylic clear coat provided by Akzo Nobel.
• Results indicate that a complete elimination of pretreatment in favor of plasma clean, plasma coating, oven baking followed by a second plasma treatment provides the enhanced surface energy enabling superior adhesion of the clear coat both at the substrate and at the base coat or color coat for improved intercoat adhesion.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Plasma & Fusion (AREA)
• Life Sciences & Earth Sciences (AREA)
• Wood Science & Technology (AREA)
• Application Of Or Painting With Fluid Materials (AREA)

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Publications (1)

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Family Applications (1)

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• 2019
  • 2019-05-03 WO PCT/US2019/030521 patent/WO2020153980A1/en unknown
  • 2019-05-03 EP EP19725456.8A patent/EP3914398A1/de not_active Withdrawn

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