WO2022055472A1

WO2022055472A1 - Housings for electronic devices

Info

Publication number: WO2022055472A1
Application number: PCT/US2020/049672
Authority: WO
Inventors: Kuan-Ting Wu WU; Chi Hao Chang; Kuo Chih Huang
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2020-09-08
Filing date: 2020-09-08
Publication date: 2022-03-17

Abstract

An anti-smudge coated housing for an electronic device can include a substrate, a waterborne paint coating applied on the substrate, and a fluoropolymer layer on the waterborne paint coating. The waterborne paint coating can have a thickness at from about 10 µm to about 100 µm and can include a polymeric resin and colorant. The fluoropolymer layer can have a thickness from about 50 nm to about 3 µm and can include poly-perfluorodecylacrylate, poly-hexafluorobutylacrylate, poly-perfluoroalkylethylacrylate, polytetrafluoroethylene, polyvinylidene fluoride, fluorinated olefin-based polymers, fluoroacrylates, fluorosilicone acrylates, fluorosiloxane, or a combination thereof.

Description

HOUSINGS FOR ELECTRONIC DEVICES

BACKGROUND

[0001 ] The use of electronic devices of all types continues to increase. Cellular phones (including smart phones), tablet computers, desktop computers, and laptop computers are used by many for personal, entertainment, and/or business purposes. Electronic devices have become a staple product of modern life. Electronic devices typically include some type of housing. As the use of electronic devices continues to rise, so does the demand for the development of housings for electronic devices.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002] FIG. 1 graphically illustrates an example anti-smudge coated housing for an electronic device housing in accordance with the present disclosure;

[0003] FIG. 2 graphically illustrates an example anti-smudge coated housing for an electronic device housing in accordance with the present disclosure;

[0004] FIG. 3 graphically illustrates an example electronic device in accordance with the present disclosure; and

[0005] FIG. 4 is a flow diagram illustrating an example method of applying an anti-smudge coating to a substrate in accordance with the present disclosure.

DETAILED DESCRIPTION

[0006] Electronic devices incorporate housings to encase and protect the electronic components of the electronic device. These housings can be manufactured from various materials and can include decorative finishes to increase aesthetic appeal. In some examples, an after-market decorative finish, such as paint, can be applied over an exterior surface of the substrate; however, application of after-market finishes can be difficult to apply evenly or neatly in some instances because the device is already assembled and may need to be masked or otherwise prepared for a typically more complicated finishing process. Furthermore, some finishes may utilize latex based paints which can have high volatile organic compound (VOC) emission issues. The VOC emissions may negatively affect the environment and may be higher than legally permitted. In addition, some finishes can have limited durability and can be susceptible to scratching and smudging.

[0007] In accordance with examples of the present disclosure, an anti-smudge coated housing for an electronic device can include a substrate, a waterborne paint coating, and a fluoropolymer layer. The waterborne paint coating can be applied on the substrate at a thickness from about 10 pm to about 55 pm. The waterborne paint coating can include a polymeric resin and a colorant. The fluoropolymer layer can be disposed on the waterborne paint coating at a thickness from about 50 nm to about 3 pm. The fluoropolymer layer can include poly-perfluorodecylacrylate, poly-hexafluorobutylacrylate, poly-perfluoroalkylethylacrylate, polytetrafluoroethylene, polyvinylidene fluoride, fluorinated olefin-based polymers, fluoroacrylates, fluorosilicone acrylates, fluorosiloxane, or a combination thereof. In an example, the waterborne paint coating can include a waterborne primer layer, a waterborne basecoat layer, or a combination thereof. In another example, the anti-smudge coated housing can further include a powder coat layer between the substrate and the waterborne paint coating. In yet another example, the substrate can include a metal and the metal can be selected from aluminum, magnesium, lithium, titanium, mixtures thereof, or alloys thereof. In a further example, the anti-smudge coated housing can further include a passivation layer that can be from about 1 pm to about 5 pm thick, a crystalline oxide layer that can be from about 1 pm to about 15 pm, and both can be positioned between the substrate and the waterborne paint layer. In one example, a surface of the anti-smudge coated housing can have a water contact angle from about 100° to about 150° and a pencil hardness from about 2H to about 5H.

[0008] Also presented herein is an electronic device. The electronic device can include an electronic component of the electronic device and an anti-smudge coated housing. The anti-smudge coated housing can include a substrate, a waterborne paint coating, and a fluoropolymer layer. The substrate can include metal, polymer, carbon fiber, or a combination thereof. The waterborne paint coating can be applied on the substrate at a thickness from about 10 pm to about 100 pm. The waterborne paint coating can include a polymeric resin. The fluoropolymer layer can be disposed on the waterborne paint coating at a thickness from about 50 nm to about 3 pm. The fluoropolymer layer including poly-perfluorodecylacrylate, poly-hexafluorobutylacrylate, poly-perfluoroalkylethylacrylate, polytetrafluoroethylene, polyvinylidene fluoride, fluorinated olefin-based polymers, fluoroacrylates, fluorosilicone acrylates, fluorosiloxane, or a combination thereof. In one example, the anti-smudge coated housing can be shaped as a laptop housing, a desktop computer housing, a smartphone housing, a tablet housing, a printer housing, a monitor housing, a keyboard housing, a headphones housing, a television housing, a speaker housing, a docking station housing, a webcam housing, a smart watch housing, a calculator housing, or a combination thereof. In another example, the substrate can include the metal and the anti-smudge coated housing can further include a passivation layer that can be from about 1 pm to about 5 pm thick, a crystalline oxide layer that can be from about 1 pm to about 15 pm thick, and both can be positioned between the substrate and the waterborne paint coating. In yet another example, the waterborne paint coating can further include from about 3 wt% to about 20 wt% colorant.

[0009] Further presented herein, in an example, is a method of applying an anti-smudge coating to a substrate of a housing for an electronic device. The method can include applying a waterborne paint coating at a total thickness from about 10 pm to about 55 pm to a surface of a substrate in the form of a waterborne primer, a waterborne basecoat, or a combination thereof. The waterborne paint coating can include from about 10 wt% to about 35 wt% polymeric resin. The method can further include depositing a fluoropolymer layer by chemical vapor deposition directly on the waterborne paint coating at a thickness that can range from about 50 nm to about 3 pm. The fluoropolymer layer can include a fluoropolymer selected from poly-perfluorodecylacrylate, poly-hexafluorobutylacrylate, poly-perfluoroalkylethylacrylate, polytetrafluoroethylene, polyvinylidene fluoride, fluorinated olefin-based polymers, fluoroacrylates, fluorosilicone acrylates, fluorosiloxane or a combination thereof. In an example, the substrate can be a metal substrate and the method can further include treating the metal substrate with a passivation treatment or a micro-arc oxidation treatment prior to applying the waterborne paint coating. In another example, the polymeric resin of the waterborne paint coating can be selected from polyacrylic, polyurethane, polyester, epoxy, polyester-imide, epoxy-polyamide, alkyd, or a combination thereof. In yet another example, a precursor gas used in the chemical vapor deposition can include from about 90 wt% to 100 wt% of the fluoropolymer, a deposition temperature during the chemical vapor deposition can range from about 70 °C to about 90 °C, and a pressure during the chemical vapor deposition can range from about 10’⁶ pascals to about 10’⁷ pascals. In a further example, the method can include degreasing the substrate in a degreasing solution, applying a powder coat layer to the substrate, or both prior to applying the waterborne paint coating.

[0010] It is noted that when discussing the anti-smudge coated housing for an electronic device, the electronic device, and/or the method of applying an anti-smudge coating to a substrate of a housing for an electronic device herein, these discussions can be considered applicable to one another whether or not they are explicitly discussed in the context of that example. Thus, for example, when discussing a substrate related to an anti-smudge coated housing for an electronic device, such disclosure is also relevant to and directly supported in the context of the electronic device, the method of applying an anti-smudge coating to a substrate of a housing for an electronic device, and vice versa.

[0011 ] It is also understood that terms used herein will take on the ordinary meaning in the relevant technical field unless specified otherwise. In some instances, there are terms defined more specifically throughout the specification or included at the end of the present specification, and thus, these terms can have a meaning as described herein. Anti-smudge Coated Housings for Electronic Devices

[0012] Anti-smudge coated housings for electronic devices, also referred to herein as “housing(s),” can have a variety of configurations which can be determined in part by the electronic device and the electric component that may be associated with the housing. For example, the housing can be a laptop housing, a desktop computer housing, a smartphone housing, a tablet housing, a printer housing, a monitor housing, a keyboard housing, a headphones housing, a television housing, a speaker housing, a docking station housing, a webcam housing, a smart watch housing, or a calculator housing, and can thus be shaped accordingly to efficiently (in some instances) provide a protective cover to the underlying electronics.

[0013] In examples herein, the anti-smudge coated housing can include a substrate that can be covered in a waterborne paint coating and a fluoropolymer layer. By way of example, FIG. 1 illustrates an anti-smudge coated housing 100, or a portion thereof, for an electronic device (not shown, but shown by way of example in FIG. 3). The anti-smudge coated housing for the electronic device can include a substrate 102, a waterborne paint coating 110, and a fluoropolymer layer 120. The waterborne paint coating, for example, can be applied on the substrate at a thickness that can range from about 10 pm to about 100 pm. The waterborne paint coating can include a polymeric resin and a colorant. The fluoropolymer layer can be applied on the waterborne paint coating at a thickness that can range from about 50 nm to about 3 pm. The fluoropolymer layer can include poly-perfluorodecylacrylate, poly-hexafluorobutylacrylate, poly-perfluoroalkylethylacrylate, polytetrafluoroethylene, polyvinylidene fluoride, fluorinated olefin-based polymers, fluoroacrylates, fluorosilicone acrylates, fluorosiloxane, or a combination thereof.

[0014] In further detail, a substrate of the housing can be shaped in the form of a housing for an electronic device. In an example, a material of the substrate can include metal, polymer, carbon fiber, or a combination thereof. In one example, a material of the substrate can include a metal and the metal can be selected from aluminum, magnesium, lithium, titanium, or mixtures or alloys thereof. In another example, the substrate can include a metal and the metal can include aluminum, magnesium, or alloys thereof. In yet another example, a material of the substrate can include a polymer and the polymer can be selected from polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), polyamide (nylon), polysulfone, polyethersulfone, polyphenylsulfone, acrylonitrile butadiene styrene/polycarbonate (ABS/PC), combinations, and co-polymers thereof. In a further example, the substrate can include a carbon fiber substrate. The carbon fiber substrate may be reinforced with a polymer, composited with other materials such as graphite, or the like.

[0015] A thickness of the substrate can vary depending on the intended housing type. For example, a thickness of a substrate that is designed for portable use such as a housing for a tablet or a cellphone may be thinner than a thickness of a housing for a product that is designed to be stationary such as a housing for a desktop computer or a printer. In some examples, the substrate can have a thickness from about 0.3 mm to about 2.0 mm. In yet other examples, the substrate can have a thickness that can range from about 0.4 mm to about 1 .2 mm, or from about 0.5 mm to about 0.8 mm.

[0016] A waterborne paint coating, as used herein, refers to a coating formed from a waterborne paint coating formulation. The waterborne paint coating formulation can be a latex free formulation that can include water as the primary solvent. Waterborne paint coating formulations may include from about 50 wt% to about 80 wt% water. Waterborne paint coating formulations can have lower volatile organic compound (VOC) emissions than comparable latex based paint coating formulations. In some examples, the VOC emissions of a waterborne paint coating formulation can be from about 65% to about 95% lower than a VOC emission of a comparable latex based paint coating formulation.

[0017] The waterborne paint coating can be a single coating or can include multiple coatings. For example, the waterborne paint coating can include a waterborne primer layer, a waterborne basecoat layer, or a combination thereof. The waterborne primer layer may be positioned closer to a surface of the substrate than the waterborne basecoat layer. The waterborne paint coating may also include multiple applications of a waterborne primer formulation or a waterborne basecoat formulation. The waterborne paint coating may also include multiple alternating layers of waterborne primer layers, and multiple waterborne basecoat layers. The amount of applications of a waterborne paint coating formulation can determine a thickness of the waterborne paint coating. The waterborne paint coating may include a polymeric resin or a polymeric resin and a colorant. Further details on the waterborne paint coating formulation that may be applied to form these coatings are described in further detail below.

[0018] As shown by example in FIG. 1 , the waterborne paint coating 110 may be applied on a surface of the substrate 102, or alternatively, as shown in FIG. 2, an anti-smudge coated housing 105 can be configured so that the waterborne paint coating 110 may be situated on a substrate surface finishing layer 130A, which may be applied directly on the surface of the substrate 102. The substrate finishing layer may likewise be applied to both sides of the substrate, as shown applied to the opposite side of the substrate at 130B. The substrate surface finishing layer can include a passivation layer, a crystalline oxide layer, a powder coat layer, or a combination thereof, and may be positioned between the surface of the substrate and the waterborne paint coating. Furthermore, the anti-smudge coated housing for the electronic device, by way of example, can include a fluoropolymer layer 120 applied on the waterborne paint coating. It is noted that there may be other intervening layers between the layers shown in FIGS. 1 and 2, or the various layers can be applied directly on the previously applied layers or substrate as shown.

[0019] In some examples, the housing may include a metal and a substrate surface finishing layer that can include a passivation layer, a crystalline oxide layer, or both. The passivation layer, the crystalline oxide layer, or both may be located on one or both sides of the substrate. In some examples, the passivation layer or the crystalline oxide layer may be located on one or both sides of the substrate. A passivation layer can include a deposit of an oxyanion on a surface of the metal substrate. The oxyanion can be selected from molybdate, vanadate, phosphate, chromate, stannate, manganese salt, or a combination thereof. These oxyanions can form an ionic bond with a metal of the surface of the substrate. In an example, the passivation layer can have a thickness that can range from about 1 pm to about 5 pm, from about 2 pm to about 4 pm, from about 1 pm to about 3 pm, or from about 3 pm to about 5 pm. A crystalline oxide layer can be an oxide layer formed by an oxidation reaction with a metal of the substrate. In some examples, the crystalline oxide layer can have a thickness that can range from about 1 pm to about 15 pm, from about 10 pm to about 15 pm, from about 1 pm to about 10 pm, from about 2 pm to about 12 pm, from about 5 pm to about 15 pm, or from about 1 pm to about 7 pm.

[0020] In yet other examples, the substrate can include a substrate surface finishing layer that can be a powder coat layer between the substrate and the waterborne paint layer. The powder coat layer may be applied to any material of a substrate or over another substrate surface finishing layer such as a passivation layer or a crystalline oxide layer. The powder coat layer can be formed from particles of a free-flowing thermoplastic or thermoset polymer that can be cured onto a surface of the housing. The thermoplastic or thermoset polymer can include epoxy, poly(vinyl chloride), polyamides, polyesters, polyurethanes, acrylics, polyphenylene ether, or combinations thereof. A thickness of the powder coat layer can range from about 30 pm to about 60 pm, from about 35 pm to about 55 pm, or from about 40 pm to about 50 pm.

[0021 ] The housing may further include a fluoropolymer layer positioned on an opposite surface of the waterborne paint coating, e.g. opposite surface with respect to a location of the substrate. The fluoropolymer layer can include a fluoropolymer that can be selected from poly-perfluorodecylacrylate, poly-hexafluorobutylacrylate, poly-perfluoroalkylethylacrylate, polytetrafluoroethylene, polyvinylidene fluoride, fluorinated olefin-based polymers, fluoroacrylates, fluorosilicone acrylates, fluorosiloxane, or a combination thereof. In an example, the fluoropolymer can be selected from poly-perfluorodecylacrylate, poly-hexafluorobutylacrylate, poly-perfluoroalkylethylacrylate, or a combination thereof. The fluoropolymer layer can have a thickness ranging from about 50 nm to about 3 pm, from about 500 nm to about 3 pm, from about 1 pm to about 3 pm, from about 50 nm to about 750 nm, from about 100 nm to about 1 pm, from about 500 nm to about 2 pm, or from about 750 nm to about 1 .5 pm. In some examples, the fluoropolymer layer may form an outermost surface of the housing. [0022] The housing can be durable and resist scratching. In some examples, the housing at a location of the fluoropolymer layer can have a pencil hardness value from about 2H to about 5H, from about 3H to about 5H, or from about 2H to about 4H. Pencil hardness is one way to quantify a hardness of the housing and can refer to the ability of a surface to resist scratching. Pencil hardness can be tested using ASTM D 3363, Standard Test Method for Film Hardness. The standard test method includes the following details: Pencil type: 6B-5B-4B-2B-B-HB-F-H-2H-3H-4H-5H-6H-7H-8H-9H (brand: Mitsubishi) with 6B being softest and 9H being hardest; Test Protocol: Force loading at 750g; drawing lead sharpened; substrate placed on a level, firm, horizontal surface; starting with the hardest lead, hold the pencil or lead in holder firmly with the lead against the substrate layer at a 45° angle (point away from the operator) and push away from the operator; allow the load weight to apply uniform pressure downward and forward as the pencil is moved to either cut or scratch the substrate or to crumble the edge of the lead (length of stroke to be 1/4 inch (6.5 mm); repeat process down the hardness scale until a pencil is found that will not scratch or gouge the substrate; the hardest pencil that does not scratch or gouge the substrate is then considered the pencil hardness of the substrate.

[0023] The housing may also be resistant to smudging, thereby rendering the housing easy to maintain a clean appearance. The housing may also be resistant to sticky residue and graffiti. These features of the housing may be characterized by a water contact angle of a surface of the housing at the fluoropolymer layer. In some examples, the housing at a location of the fluoropolymer layer can have a water contact angle of from about 100° to about 150°, from about 100° to about 130°, from about 120° to about 140°, or from about 115° to about 130°. Water contact angle can be measured by an optical tensiometer. The optical tensiometer can dispense a 0.1 pL water drop on the fluoropolymer layer of the housing, a digital camera can take an image of the droplet on the surface, and the contact angle of the droplet with respect to the surface of the fluoropolymer layer can be digitally measured. A water contact angle can be measured according to ASTM D7334 standard. Electronic Devices

[0024] An example anti-smudge coated housing 100 is shown as part of an electronic device 200 as shown in FIG. 3. The anti-smudge coated housing can encase an electronic component 205 of an electronic device 200, for example. The housing can include a substrate 102 that can have an interior surface 104 and an exterior surface 106. The exterior surface in this example includes a waterborne paint coating 110 applied directly thereto, though there can be intervening layers in some examples. Additionally, a fluoropolymer layer 120 is shown as applied directly on the waterborne paint coating, though there can be intervening layers as previously mentioned. Thus, the interior surface of the substrate can be adjacent to the electronic component of the electronic device. An interior surface may include a substrate surface finishing layer, as shown in FIG. 2. The housing, substrate, waterborne paint coating, fluoropolymer layer, and substrate surface finishing layer(s), if present, can be as described previously.

[0025] The electronic component can include any electric component of any electrical device. In some examples, the electronic component can include electronic components for a laptop, a desktop, a smartphone, a tablet, a printer, a monitor, a keyboard, a pair of headphones, a television, a speaker, a docking station, a webcam, a smart watch, a calculator, or the like. In some examples, the electronic device can be a laptop, a desktop, a smartphone, a tablet, a printer, a monitor, a keyboard, a pair of headphones, a television, a speaker, a docking station, a webcam, a smart watch, or a calculator. Thus, the housing can be a laptop housing, a desktop computer housing, a smartphone housing, a tablet housing, a printer housing, a monitor housing, a keyboard housing, a headphones housing, a television housing, a speaker housing, a docking station housing, a webcam housing, a smart watch housing, or a calculator housing, for example.

Methods of Applying Anti-smudge Coatings to Housings for Electronic Devices [0026] A flow diagram of an example method 300 of applying an anti-smudge coating to a substrate of a housing for an electronic device is shown in FIG. 4. The method can include applying 310 a waterborne paint coating at a total thickness from about 10 m to about 55 pm to a surface of a substrate in the form of a waterborne primer, a waterborne basecoat, or a combination thereof. The waterborne paint coating can include from about 10 wt% to about 35 wt% polymeric resin. The method can further include depositing 320 a fluoropolymer layer by chemical vapor deposition directly on the waterborne paint coating at a thickness from about 50 nm to about 3 pm, where the fluoropolymer layer can include poly-perfluorodecylacrylate, poly-hexafluorobutylacrylate, poly-perfluoroalkylethylacrylate, polytetrafluoroethylene, polyvinylidene fluoride, fluorinated olefin-based polymers, fluoroacrylates, fluorosilicone acrylates, fluorosiloxane, or a combination thereof. In some examples, the method can further include degreasing a substrate in preparation for applying the anti-smudge coating. In yet other examples, the method can further include applying a substrate surface finishing layer, such as a passivation layer, a crystalline oxide layer, a powder coat layer, or a combination thereof to a surface of the substrate prior to applying the waterborne paint coating.

[0027] In further detail, the method can include degreasing the substrate. This can include submerging the substrate in a degreasing solution, rinsing the substrate, and allowing the substrate to dry after rinsing. The degreasing solution can include a sodium compound and water. The sodium compound can include sodium caseinate, sodium polyacrylate, sodium polyoxyethylene alkyl ether carboxylate, sodium dodecyl sulfate, or a combination thereof. The sodium compound can be present in the degreasing solution at from about 0.3 wt% to about 2 wt% or from about 0.5 wt% to about 1 .5 wt%. The degreasing solution can further include water. The water may be deionized. A pH of the degreasing solution may be adjusted with potassium hydroxide or sodium hydroxide to a pH ranging from about 9 to about 13.

[0028] The degreasing solution may be warmed to a temperature ranging from about 20 °C to about 60 °C. In other examples, the degreasing solution can be warmed to a temperature ranging from about 20 °C to about 25 °C, from about 20 °C to about 40 °C, from about 40 °C to about 60 °C, or from about 25 °C to about 50 °C. The substrate can be dipped in the degreasing solution for a period of time ranging from about 30 seconds to about 180 seconds, from about 30 seconds to about 60 seconds, from about 60 seconds to about 180 seconds, or from about 60 seconds to about 120 seconds. In some examples, the degreasing solution can be sonicated and from about 15 kHz to about 400 kHz, from about 200 kHz to about 400 kHz, or from about 15 kHz to about 250 kHz can be applied. Following submerging the substrate in the degreasing solution, the substrate can be rinsed with water or deionized water to remove the degreasing solution. In some examples, the submerging and/or rinsing can be repeated. The substrate may then be allowed to air dry before additional treatment.

[0029] A substrate that includes a metal may be treated in an oxyanion chemical bath to form a passivation layer thereon. The oxyanion chemical bath can include an oxyanion selected from molybdate, vanadate, phosphate, chromate, stannate, manganese salt, or a combination thereof. In one example, the oxyanion can include a manganese salt and the manganese salt can be selected from manganese sulfate, manganese chloride, manganese acetate, manganese carbonate, or a combination thereof. The oxyanion may be present in the oxyanion chemical bath at from about 3 wt% to about 15 wt%, from about 3 wt% to about 12 wt%, from about 5 wt% to about 15 wt%, from about 6 wt% to about 12 wt%, or from about 5 wt% to about 10 wt%. The oxyanion chemical bath can further include water. The water may be deionized.

[0030] The oxyanion chemical bath may be warmed to a temperature ranging from about 20 °C to about 50 °C. In other examples, the oxyanion chemical bath may be warmed to a temperature ranging from about 22 °C to about 45 °C, from about 25 °C to about 40 °C, or from about 30 °C to about 35 °C. The substrate can be submerged in the oxyanion chemical bath for a period of time ranging from about 20 seconds to about 120 seconds, from about 20 seconds to about 80 seconds, from about 60 seconds to about 120 seconds, or from about 40 seconds to about 100 seconds. The longer the substrate is submerged, the thicker the passivation layer formed thereon will be. The substrate may be allowed to air dry before additional treatment.

[0031 ] A substrate that includes a metal may be alternatively or additionally treated in an oxidizing solution that can interact with the metal of the substrate to form a crystalline oxide layer thereon. The oxidizing solution can include sodium silicate, sodium phosphate, potassium fluoride, potassium hydroxide, sodium hydroxide, fluorozirconate, sodium hexametaphosphate, sodium fluoride, ferric ammonium oxalate, phosphoric acid salt, graphite powder, silicon dioxide powder, aluminum oxide powder, zinc powder, or a combination thereof. In one example, the oxidizing solution can include sodium silicate, potassium fluoride, potassium hydroxide, sodium hydroxide, fluorozirconate, sodium hexametaphosphate, sodium fluoride, ferric ammonium oxalate, phosphoric acid salt, graphite powder, silicon dioxide powder, aluminum oxide powder, or a combination thereof. In yet another example, the oxidizing solution can include a metal phosphate, a metal powder, or a combination thereof and the metal can be selected from aluminum, zinc, zirconium, tin, an alloy, or a combination thereof. The oxyanion can be present in the oxyanion chemical bath at from about 3 wt% to about 15 wt%, from about 3 wt% to about 12 wt%, from about 5 wt% to about 15 wt%, from about 6 wt% to about 12 wt%, or from about 5 wt% to about 10 wt%. The oxyanion chemical bath can further include water. The water may be deionized. In some examples, a pH of the oxyanion chemical bath may be adjusted. The adjustment can occur through an addition of potassium hydroxide, sodium hydroxide, or a combination thereof in an amount to adjust the pH to within the range of from about 8 to about 13.

[0032] The oxyanion chemical bath may be warmed to a temperature ranging from about 10 °C to about 45 °C. In other examples, the oxyanion chemical bath may be warmed to a temperature ranging from about 10 °C to about 30 °C, from about 20 °C to about 40 °C, or from about 15 °C to about 45 °C. A voltage ranging from about 150 V to about 550 V, from about 150 V to about 300 V, from about 300 V to about 550 V, or from about 200 V to about 400 V can be applied to the oxyanion chemical bath. The substrate can be submerged in the oxyanion chemical bath for a period of time ranging from about 2 minutes to about 25 minutes, from about 5 minutes to about 25 minutes, from about 10 minutes to about 20 minutes, from about 15 minutes to about 25 minutes, or from about 2 minutes to about 12 minutes. The longer the substrate is submerged in the oxyanion chemical bath, the thicker the crystalline oxide layer formed on the substrate will be. The substrate may be allowed to air dry before additional treatment.

[0033] A powder coat layer may be applied to the substrate. The powder coat layer may be applied adjacent to a surface of the substrate, adjacent to a passivation layer, adjacent to a crystalline oxide layer, or a combination thereof. The powder coat layer can be electrostatically applied as a free-flowing dry powder that can be heat cured on the surface. The dry powder can include particles of epoxy, poly(vinyl chloride), polyamides, polyesters, polyurethanes, acrylics, polyphenylene ether, or a combination thereof. Particles of the dry powder can have a D50 particle size ranging from about 2 pm to about 50 pm, from about 5 pm to about 45 pm, or from about 10 pm to about 40 pm. “D50” particle size as used herein, is defined as the particle size at which about half of the particles are larger than the D50 particle size and about half of the other particles are smaller than the D50 particle size (by weight based on the particle content). As used herein, particle size can be based on volume of the particle size normalized to a spherical shape for diameter measurement, for example. Particle size can be collected using a Malvern ZETASIZER™ from Malvern Panalytical (United Kingdom), for example. Particle size can also be determined and/or verified using a scanning electron microscope (SEM), or can be measured using a particle analyzer such as the MASTERSIZER™ 3000 available from Malvern Panalytical (United Kingdom), for example. The particle analyzer can measure particle size using laser diffraction. A laser beam can pass through a sample of particles and the angular variation in intensity of light scattered by the particles can be measured. Larger particles scatter light at smaller angles, while smaller particles scatter light at larger angles. The particle analyzer can then analyze the angular scattering data to calculate the size of the particles using the Mie theory of light scattering. The particle size can be reported as a volume equivalent sphere diameter.

[0034] The powder may be heat cured on the substrate at a temperature ranging from about 150 °C to about 190 °C, from about 160 °C to about 180 °C, from about 150 °C to about 175 °C, or from about 170 °C to about 190 °C. In some examples, heat curing can occur in an oven. In yet other examples, heat curing can occur under a UV light. Heat curing can occur over a time period ranging from about 3 minutes to about 40 minutes, from about 5 minutes to about 30 minutes, from about 20 minutes to about 40 minutes, from about 10 minutes to about 30 minutes, or from about 3 minutes to about 23 minutes. [0035] The waterborne paint coating may be applied on a surface of the substrate, or on a surface of the substrate surface finishing layer, such as a passivation layer, a crystalline oxide layer, a powder coat layer, or a combination thereof which may be positioned on the substrate. The waterborne paint coating may include a waterborne basecoat layer, a waterborne basecoat layer, or a combination thereof. In some examples, the waterborne paint coating may include multiple layers of a coating such as about 1 , about 2, about 3, or about 4 applications of the waterborne primer formulation; about 1 , about 2, about 3, or about 4 applications of the waterborne basecoat formulation; or a combination thereof. The more applications, the thicker the waterborne paint coating will be.

[0036] A waterborne primer layer may be formed through application of a waterborne primer formulation. A waterborne basecoat layer may be formed through application of a waterborne basecoat formulation. The waterborne paint coating formulation can include a polymeric resin. The polymeric resin can include in some examples, polyacrylic, polyurethane, polyester, epoxy, polyester-imide, epoxy-polyamide, alkyd, or a combination thereof. In yet other examples, the polymeric resin can include a polyacrylic, polyurethane, polyester, epoxy, or a combination thereof. The polymeric resin can be present at from about 10 wt% to about 35 wt%, from about 15 wt% to about 30 wt%, from about 10 wt% to about 20 wt%, or from about 20 wt% to about 35 wt%. The waterborne primer formulation can include water as the primary solvent. The water may be deionized. In some examples water may be present at from about 50 wt% to about 80 wt%, from about 60 wt% to about 80 wt%, or from about 50 wt% to 70 wt%.

[0037] In some examples, the waterborne paint coating formulation may further include a co-solvent, a surfactant, a colorant, or a combination thereof. In some examples, a co-solvent can be selected from a polyol, an oligoglycol, or a lactam. In another example, the organic co-solvent can be a polyol. In one example, a co-solvent can be selected from diols; 1 ,2 butanediol; 1 ,2-propanediol; 2,3-butanediol; 1 ,2-pentanediol; 2-methyl-2,4-pentanediol; 2-methyl-1 ,3-propanediol; triols; tetrahydrofuran; ethylene glycol dimethyl ether; ethylene glycol diethylene glycol; triethylene glycol; propylene glycol; tripropylene glycol butyl ether; lactams; 2-pyrrolidone; 1 -(2-hydroxyl)-2-pyrrolidone; or a combination thereof. In another example, a co-solvent can be a diol and the diol can be selected from 1 ,2 butanediol; 1 ,2-propanediol; 2,3-butanediol; 1 ,2-pentanediol; 2-methyl-2,4-pentanediol; 2-methyl-1 ,3-propanediol; or a combination thereof. In yet another example, a co-solvent can be 1 ,2 butanediol. The co-solvent may be present at from about 5 wt% to about 20 wt%, from about 10 wt% to about 20 wt%, from about 12 wt% to about 18 wt%, from about 7 wt% to about 15 wt%, or from about 15 wt% to about 20 wt% in the waterborne paint coating formulation.

[0038] In some examples, the waterborne paint coating formulation may include a surfactant. The surfactant can include a non-ionic surfactant, a cationic surfactant, and/or an anionic surfactant. Example non-ionic surfactants can include self-emulsifiable, nonionic wetting agents based on acetylenic diol chemistry (e.g., SURFYNOL® SEF from Air Products and Chemicals, Inc., USA), a fluorosurfactant (e.g., CAPSTONE® fluorosurfactants from DuPont, USA), or a combination thereof. In other examples, the surfactant can be an ethoxylated low-foam wetting agent (e.g., SURFYNOL® 440, SURFYNOL® 465, or SURFYNOL® CT-111 from Air Products and Chemical Inc., USA), or an ethoxylated wetting agent and molecular defoamer (e.g., SURFYNOL® 420 from Air Products and Chemical Inc., USA). Still other examples of surfactants can include wetting agents and molecular defoamers (e.g., SURFYNOL® 104E from Air Products and Chemical Inc., USA), alkylphenylethoxylates, solvent-free surfactant blends (e.g., SURFYNOL® CT-211 from Air Products and Chemicals, Inc., USA), water-soluble surfactant (e.g., TERGITOL® TMN-6, TERGITOL® 15S7, and TERGITOL® 15S9 from The Dow Chemical Company, USA), or a combination thereof. In other examples, the surfactant can include non-ionic organic surfactants (e.g., TEGO® Wet 510 from Evonik Industries AG, Germany), a non-ionic secondary alcohol ethoxylate (e.g., TERGITOL® 15-S-5, TERGITOL® 15-S-7, TERGITOL® 15-S-9, and TERGITOL® 15-S-30 all from Dow Chemical Company, USA), or a combination thereof. Example anionic surfactants can include alkyldiphenyloxide disulfonate (e.g., DOWFAX® 8390 and DOWFAX® 2A1 from The Dow Chemical Company, USA), and oleth-3 phosphate surfactant (e.g., CRODAFOS™ N3 Acid from Croda, UK). Example cationic surfactants can include dodecyltrimethylammonium chloride, hexadecyldimethylammonium chloride, or a combination thereof. In some examples, the surfactant can include a co-polymerizable surfactant. Co-polymerizable surfactants can include polyoxyethylene alkylphenyl ether ammonium sulfate, sodium polyoxyethylene alkylether sulfuric ester, polyoxyethylene styrenated phenyl ether ammonium sulfate, or mixtures thereof. The surfactant may be present at from about 0.3 wt% to about 3 wt%, from about 0.5 wt% to about 1 .5 wt%, from about 1 wt% to about 3 wt%, or from about 0.5 wt% to about 2.5 wt% in the waterborne paint coating formulation.

[0039] In some examples, the waterborne paint coating formulation may further include a colorant. The colorant may differ based on the formulation. A waterborne primer formulation can include a colorant that can have a high refractive index to assist in shielding a surface of the substrate. For example, a waterborne primer formulation may include titanium dioxide, a high platy pigment, or a combination thereof. A waterborne basecoat formulation can include a colorant to meet the coloration desires of the end user. In some examples, the colorant can include a pigment, a dye, or both a pigment and a dye. The colorant may include any colorant combination to achieve the desired coloration. For example, the colorant can include a single pigment, multiple pigments, a single dye, multiple dyes, a single pigment and a single dye, multiple pigments and a single dye, a single pigment and multiple dyes, or multiple pigments and multiple dyes. In an example, the colorant may include a pigment and the pigment may be selected from azo pigments including diazo pigments and monoazo pigments; polycyclic pigments (e.g., phthalocyanine pigments such as phthalocyanine blues and phthalocyanine greens, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, pyranthrone pigments, and quinophthalone pigments); nitro pigments; nitroso pigments; anthanthrone pigments; or a combination thereof. In an example, the pigment may be selected from carbon black, graphene, titanium dioxide, clay, mica, talc, barium sulfate, calcium carbonate, metallic powder, aluminum oxide, glass bead, hollow sphere plastic pigment, or a combination thereof. In another example, the colorant may include a dye and the dye may be selected from Alexa Fluor 594 dye, Texas Red, Pacific Blue dye, Pacific Orange, Quinoline Yellow WS, or a combination thereof. In some examples, no colorant may be present. When a colorant is present, the colorant may be present at from about 0.1 wt% to about 15 wt%, from about 0.3 wt% to about 10 wt%, or from about 0.5 wt% to about 8 wt% in the waterborne paint coating formulation. The waterborne paint coating formulations can be latex free.

[0040] The waterborne paint coating formulations may be applied as a spray coating at a temperature ranging from about 80 °C to about 120 °C, from about 100 °C to about 120 °C, from about 90 °C to about 110 °C, or from about 85 °C to about 115 °C. A layer of the waterborne paint coating formulation may be allowed to dry to the touch prior to application of successive layers. For example, a waterborne paint coating formulation may be allowed to air dry for about 3 minutes to about 20 minutes, for about 5 minutes to about 15 minutes, or for about 10 minutes to about 20 minutes before an additional waterborne paint coating formulation or a fluoropolymer layer are applied thereto.

[0041 ] The fluoropolymer layer can be applied to a surface of the waterborne paint coating. The fluoropolymer layer may be formed by chemical vapor deposition. During chemical vapor deposition, the substrate including the waterborne paint coating can be positioned in a chamber and a precursor gas can be pumped into the chamber. The precursor gas can include a fluoropolymer that can be deposited on a surface of the waterborne paint coating. The fluoropolymer in precursor gas can include poly-perfluorodecylacrylates, poly-hexafluorobutylacrylates, poly-perfluoroalkylethylacrylates, polytetrafluoroethylenes, polyvinylidene fluorides, fluorinated olefin-based polymers, fluoroacrylates, fluorosilicone acrylates, fluorosiloxanes, or a combination thereof. In another example, a fluoropolymer in the precursor gas can include poly-perfluorodecylacrylates, poly-hexafluorobutylacrylates, poly-perfluoroalkylethylacrylates, or a combination thereof. The fluoropolymer can be present in the precursor gas at from about 90 wt% to 100 wt%, from about 90 wt% to about 95 wt%, from about 95 wt% to 100 wt%, from about 92 wt% to about 98 wt%, or at 100 wt%.The chamber may be heated during the chemical vapor deposition process. A temperature during the chemical vapor deposition can range from about 70 °C to about 90 °C, from about 80 °C to about 90 °C, from about 70 °C to about 80 °C, or from about 75 °C to about 85 °C. A pressure during the chemical vapor deposition can range from about 10’⁶ pascals to about 10’⁷ pascals. An exposure period of the substrate to the precursor gas can determine a thickness of the fluoropolymer layer formed on the substrate. In some examples, the chemical vapor deposition can occur for a period of time ranging from about 10 minutes to about 30 minutes or from about 15 minutes to about 25 minutes.

Definitions

[0042] It is noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise.

[0043] The term "about" as used herein, when referring to a numerical value or range, allows for a degree of variability in the value or range, for example, within 10%, or, in one aspect within 5%, of a stated value or of a stated limit of a range. The term “about” when modifying a numerical range is also understood to include as one numerical subrange a range defined by the exact numerical value indicated, e.g., the range of about 1 wt% to about 5 wt% includes 1 wt% to 5 wt% as an explicitly supported sub-range.

[0044] As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though the individual member of the list is identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list based on presentation in a common group without indications to the contrary.

[0045] Concentrations, dimensions, amounts, and other numerical data may be presented herein in a range format. It is to be understood that such range format is used merely for convenience and brevity and should be interpreted flexibly to include the numerical values explicitly recited as the limits of the range, as well as to include all the individual numerical values or sub-ranges encompassed within that range as the individual numerical value and/or sub-range is explicitly recited. For example, a weight ratio range of about 1 wt% to about 20 wt% should be interpreted to include the explicitly recited limits of 1 wt% and 20 wt% and to include individual weights such as about 2 wt%, about 11 wt%, about 14 wt%, and sub-ranges such as about 10 wt% to about 20 wt%, about 5 wt% to about 15 wt%, etc.

EXAMPLES

[0046] The following examples illustrate the technology of the present disclosure. However, it is to be understood that the following is merely illustrative of the housings, electronic devices, and methods herein. Numerous modifications and alternative methods and systems may be devised without departing from the present disclosure. Thus, while the technology has been described above with particularity, the following provides further detail in connection with what are presently deemed to be the acceptable examples.

Example 1 - Electronic Device Housing

[0047] An example electronic device housing is prepared as follows. A 0.7 mm thick magnesium alloy substrate in the shape of a housing for an electronic device is cleaned by submerging the substrate in a degreasing solution for about 30 seconds to about 180 seconds. The degreasing solution includes from about 0.3 wt% to about 2 wt% of a sodium compound and water. The sodium compound includes sodium caseinate, sodium polyacrylate, sodium polyoxyethylene alkyl ether carboxylate, sodium dodecyl sulfate, or a combination thereof. The magnesium alloy substrate is rinsed with deionized water and allowed to air dry. A waterborne paint coating is spray coated on the cleaned magnesium alloy substrate. The waterborne paint coating includes from about 10 wt% to about 35 wt% of a polymeric resin selected from a polyacrylic, polyurethane, polyester, epoxy, or a combination thereof with water to balance. Following application of the waterborne paint coating, the substrate with the waterborne paint coating thereon is alowed to air dry to the touch. A fluoropolymer layer is then applied over the waterborne paint coating by chemical vapor deposition of a fluoropolymer. The fluoropolymer in this example is selected from poly-perfluorodecylacrylate, poly-hexafluorobutylacrylate, poly-perfluoroalkylethylacrylate, polytetrafluoroethylene, polyvinylidene fluoride, fluorinated olefin-based polymers, fluoroacrylates, fluorosilicone acrylates, fluorosiloxane, or a combination thereof and in this example is present in a gas at from about 90 wt% to 100 wt%. The housing formed results in an anti-smudge coating and has a pencil hardness value of from about 3H to about 5H at the fluoropolymer layer and a water contact angle of from about 100 ° to about 150 ° at the fluoropolymer layer.

Example 2 - Assembly of an Electronic Device

[0048] An electronic device housing as described above in Example 1 is placed to partially surround an electronics circuit board of a smart phone or tablet computer. The housing is placed such that a metal surface containing waterborne paint coating and the fluoropolymer layer is on an exterior surface of the substrate to which they are applied relative to the positioning of the electronic component. The electronic device has an aesthetically pleasing colored appearance and exhibits smudge resistance.

Claims

CLAIMS What is Claimed Is:

1 . An anti-smudge coated housing for an electronic device, comprising: a substrate; a waterborne paint coating applied on the substrate at a thickness from about 10 pm to about 100 pm, the waterborne paint coating including a polymeric resin and colorant; and a fluoropolymer layer on the waterborne paint coating at a thickness from about 50 nm to about 3 pm, the fluoropolymer layer including poly-perfluorodecylacrylate, poly-hexafluorobutylacrylate, poly-perfluoroalkylethylacrylate, polytetrafluoroethylene, polyvinylidene fluoride, fluorinated olefin-based polymers, fluoroacrylates, fluorosilicone acrylates, fluorosiloxane, or a combination thereof.

2. The anti-smudge coated housing of claim 1 , wherein the waterborne paint coating includes a waterborne primer layer, a waterborne basecoat layer, or a combination thereof.

3. The anti-smudge coated housing of claim 1 , wherein anti-smudge coated housing further includes a powder coat layer between the substrate and the waterborne paint layer.

4. The anti-smudge coated housing of claim 1 , wherein the substrate includes a metal selected from aluminum, magnesium, lithium, titanium, mixtures thereof, or alloys thereof.

5. The anti-smudge coated housing of claim 4, wherein the anti-smudge coated housing further includes a passivation layer that is from about 1 pm to about 5 pm

22 thick, a crystalline oxide layer from about 1 m to about 15 pm thick, or both positioned between the substrate and the waterborne paint coating.

6. The anti-smudge coated housing of claim 4, wherein a surface of the anti-smudge coated housing has a water contact angle from about 100° to about 150° and a pencil hardness from about 2H to about 5H.

7. An electronic device, comprising: an electronic component of an electronic device; and an anti-smudge coated housing to support the electronic components, the anti-smudge coated housing, comprising: a substrate including metal, polymer, carbon fiber, or a combination thereof, a waterborne paint coating applied on the substrate at a thickness from about 10 pm to about 100 pm, the waterborne paint coating including a polymeric resin, and a fluoropolymer layer on the waterborne paint coating at a thickness from about 50 nm to about 3 pm, the fluoropolymer layer including poly-perfluorodecylacrylate, poly-hexafluorobutylacrylate, poly-perfluoroalkylethylacrylate, polytetrafluoroethylene, polyvinylidene fluoride, fluorinated olefin-based polymers, fluoroacrylates, fluorosilicone acrylates, fluorosiloxane, or a combination thereof.

8. The electronic device of claim 7, wherein the anti-smudge coated housing is shaped as a housing of a laptop housing, a desktop computer housing, a smartphone housing, a tablet housing, a printer housing, a monitor housing, a keyboard housing, a headphones housing, a television housing, a speaker housing, a docking station housing, a webcam housing, a smart watch housing, or a calculator housing, or a combination thereof.

9. The electronic device of claim 7, wherein the substrate includes the metal and the anti-smudge coated housing further includes a passivation layer that is from about 1 pm to about 5 pm thick, a crystalline oxide layer from about 1 pm to about 15 pm thick, or both positioned between the substrate and the waterborne paint coating.

10. The electronic device of claim 7, wherein the waterborne paint coating further includes from about 3 wt% to about 20 wt% colorant.

11. A method of applying an anti-smudge coating to a substrate of a housing for an electronic device, comprising: applying a waterborne paint coating at a total thickness from about 10 pm to about 55 pm to a surface of a substrate in the form of a waterborne primer, a waterborne basecoat, or a combination thereof, wherein the waterborne paint coating includes from about 10 wt% to about 35 wt% polymeric resin; and depositing a fluoropolymer layer by chemical vapor deposition directly on the waterborne paint coating at a thickness from about 50 nm to about 3 pm, wherein the fluoropolymer layer includes poly-perfluorodecylacrylate, poly-hexafluorobutylacrylate, poly-perfluoroalkylethylacrylate, polytetrafluoroethylene, polyvinylidene fluoride, fluorinated olefin-based polymers, fluoroacrylates, fluorosilicone acrylates, fluorosiloxane, or a combination thereof.

12. The method of claim 11 , wherein the substrate is a metal substrate and the method further includes treating the metal substrate with a passivation treatment or a micro-arc oxidation treatment prior to applying the waterborne paint coating.

13. The method of claim 11 , wherein the polymeric resin of the waterborne paint coating is selected from polyacrylic, polyurethane, polyester, epoxy, polyester-imide, epoxy-polyamide, alkyd, or a combination thereof.

14. The method of claim 11 , wherein a precursor gas used in the chemical vapor deposition includes from about 90 wt% to 100 wt% of the fluoropolymer, a deposition temperature during the chemical vapor deposition ranges from about 70 °C to about 90 °C, and a pressure during the chemical vapor deposition ranges from about 10’⁶ pascals to about 10’⁷ pascals.

15. The method of claim 11 , wherein the method further comprises degreasing the substrate in a degreasing solution, applying a powder coat layer to the substrate, or both prior to applying the waterborne paint coating.