Process for producing a polyolefin part, a polyolefin part, and use thereof

Abstract

A process for producing a polyolefin part includes treating a surface of the polyolefin part to provide an activated polyolefin surface; applying a primer directly on the activated polyolefin surface; applying a base coat directly on the primer; and removing a portion of the base coat by laser etching while retaining at least a portion of the primer present between the base coat and the activated polyolefin surface; and applying a clear coat directly on remaining base coat and exposed primer.

Description

[0001] PROCESS FOR PRODUCING A POLYOLEFIN PART, A POLYOLEFIN PART, AND USE THEREOF

[0002] Background

[0003] Amorphous materials like polycarbonate, with high light transparency, can be used in automotive parts such as trims, smart bumpers, etc. with integrated lighting systems (backlit panels), e.g., for various indicators (charging, welcome). Such automotive parts can further be enhanced by decoration technologies like laser etching, e.g., ablation, film over-molding, or a combination thereof. However, amorphous materials like polycarbonate used for lighting effects (e.g., hidden until lit) can be difficult to integrate in polypropylene bumpers and can be challenging for processing and recycling.

[0004] Summary of the invention

[0005] Provided is a process for producing a polyolefin part including treating a surface of the polyolefin part to provide an activated polyolefin surface; applying a primer directly on the activated polyolefin surface; applying a base coat directly on the primer; and removing a portion of the base coat by laser etching while retaining at least a portion of the primer present between the base coat and the activated polyolefin surface; and applying a clear coat directly on remaining base coat and exposed primer.

[0006] Treating the surface of the polyolefin can include treating with a flame or plasma.

[0007] T reating the surface of the polyolefin can include treating with a flame of a propaneincluding gas, said propane-including gas being propane or a mixture including at least 50 wt. % of propane based on a weight of the propane-including gas with methane, ethane, butane, pentane, hexane, or a combination thereof, wherein, during treatment with the flame of the propane-including gas, a flame is produced by burning a mixture of air and the propane-including gas, wherein the gas-to-air ratio is chosen such that the propane gas to oxygen volume ratio is equal to or less than 1 :5.01. The polyolefin can include polypropylene.

[0008] The polyolefin can have a haze of 73 to 100% and transmittance of 40 to 70%.

[0009] The primer can have a transparency of 40 to 100%.

[0010] The primer can include 2-2-butoxyethoxy)ethanol.

[0011] The base coat can include butan-1-ol, 2-(2-butoxyethoxy)ethanol, propan-2-ol, and 2-dimethylaminoethanol.

[0012] All of the primer present between the base coat and the activated polyolefin surface can be retained.

[0013] A thickness of greater than or equal to 1 micrometers of the primer present between the base coat and the activated polyolefin surface can be retained.

[0014] The clear coat can include an acrylic monomer, an epoxy, a polyurethane, a polysiloxane or a combination thereof.

[0015] Provided is a polyolefin part prepared by the process.

[0016] The clear coat can be present directly on the exposed primer in an area corresponding to a sensor accommodating portion, a light accommodating portion, a camera accommodating portion, a display accommodating portion, a receiver accommodating portion, a transmitter accommodating portion, or a combination thereof.

[0017] The polyolefin part can be a vehicle part.

[0018] Provided is a vehicle including the polyolefin part.

[0019] Detailed description

[0020] The present inventors made a surprising discovery that a base coat applied on a primer applied to a polyolefin part can be removed (e.g., laser etched or ablated) without also removing the primer underneath the base coat. Accordingly, a desired polyolefin part can be produced without a second activation of a polyolefin surface after laser etching, e.g., ablation, of a base coat applied to a plastic part. Such second activation would otherwise be performed to ensure adherence of a clear coat on a polyolefin surface from which paint is removed.

[0021] Provided herein are processes for producing the polyolefin part. The process can include (i) treatment, e.g., surface activation, of polyolefin; (ii) application of primer and base coat (black or colored) to the polyolefin; (iii) removal of the base coat by laser etching, e.g., ablation, to expose primer; (iv) application of a clear coat on remaining base coat and exposed primer. The polyolefin can be translucent and the primer can be transparent and the base coat can be removed from areas of the part to be backlit, e.g., exposing a lighting feature located behind the polyolefin part.

[0022] Polyolefin

[0023] The polyolefin can be polypropylene, polyethylene, or a combination thereof. The polyolefin can include at least 45 weight percent (wt. %) polypropylene based on the total weight of the polyolefin.

[0024] A combination of polypropylene and polyethylene can include a heterophasic propylene copolymer or polypropylene impact copolymer, which is a polypropylene blended with an elastomer impact modifier, such as polyethylene particles, C2-C8(ethylene-octene copolymer) elastomer impact modifier or C2-C4(ethylene-butene copolymer) impact modifier or SEBS (styrene ethylene butadiene styrene) impact modifier.

[0025] The polyolefin can optionally be reinforced, e.g., with fibers, particles, flakes, or a combination thereof, such as especially for example, long glass fibers, short glass fibers, glass beads, talc, mica, inorganic fillers, natural fibers, conductive fillers, carbon fibers, or a combination thereof. For example, the polyolefin can be a STAMAX® material, a long glass fiber reinforced polypropylene commercially available from SABIC.

[0026] The polyolefin can be translucent and can include a polypropylene compound or a co-polymer thereof. The translucent polyolefin part can include a translucent polypropylene compound, such as QRYSTAL™ by SABIC. Translucency can be affected by fillers such as fibers, particles, flakes, or a combination thereof, which can be omitted from translucent polyolefin.

[0027] The polyolefin can have a haze of 73 to 100% and transmittance of 40 to 70%. As used herein, unless specified otherwise, “haze” is measured in accordance with ASTM D1003-00, at the component thickness, using Procedure A, on a HAZEGUARD DUAL from BYK-Gardner with an integrating sphere (07diffuse geometry) and a spectral sensitivity conforming to the International Commission on Illumination (CIE) standard spectral value under standard lamp D65.

[0028] The polyolefin can include a polypropylene as described in, for example, W02017076770A1 , WO2017076772A1 , WO2018019764A1 , or WO2019043087A1 .

[0029] Surface treatment

[0030] The following definitions are used in the present description.

[0031] “Activation of the surface or surface activation”, as used in the present application, means, modification of the surface chemistry of a solid, e.g., a polyolefin part, leading to an increase of its surface energy (also known as surface free energy), an increase of the polar part contributing to the surface energy, a decrease of the contact angle of the surface with water, or a combination thereof.

[0032] “Surface energy”, as used in the present application, means the surface free energy calculated according to the Owens, Wendt, Rabel and Kaelble method, which is a standard method for calculating the surface free energy (SFE) of a solid from the contact angle with two liquids water, diiodomethane. This allows for the determination of the surface energy, which is divided into a polar part and a disperse (or dispersive) part.

[0033] Surface treatment or activation can include flame treatment. The flame treatment can be performed using a burner for producing the flame. The burner is fed with a defined mixture of a fuel (gas including propane) and an oxidiser (air), thoroughly premixed before combustion. In the flame treatment, during the application of heat by the flame, bonds between atoms, molecular chains, or a combination thereof are broken up on the surface and oxygen contents contained in the flame are bound to the breaking point. In this way polar molecules arise on the surface of the original non-polar material. The mechanical properties of the surfaces do not change.

[0034] Variables affecting the flame treatment are for example, the gas-to-air ratio, the composition of the gas, the gap between the burner nozzles and the surface being treated, the treatment speed, and the total flow of gas and air mixture. These variables affect the temperature reached on the surface being treated during the flame treatment.

[0035] By using a propane-containing gas being propane or a mixture including at least 50 wt. % of propane the surface being treated is activated. The gas including propane can include at least 80 wt. % of propane, or at least 95 wt. % of propane, such as for example, at least 99 wt. % of propane or even 100 wt. % of propane.

[0036] During treatment with a flame of a gas including propane, a flame is produced by burning a mixture of air and the gas including propane, wherein the gas-to-air ratio is chosen such that the propane to oxygen ratio is equal to or less than 1 : 5.01 . This also contributes to a further activation of the surface being treated.

[0037] A burner can be used for producing the flame, said burner including at least one nozzle for providing a mixture of air and the gas including propane to be burned. The gap between the at least one nozzle and the surface being treated influences the extent of activation accomplished by the flame treatment. A too large distance between the cone of the flame and surface being treated causes the surface activation to decrease. A too low distance between the cone of the flame and the surface being treated can damage the surface.

[0038] The treatment speed may, for example, be between 200 millimeters per second (mm / s) and 1 ,200 mm / s, for example, between 250 mm / s and 1 ,000 mm / s, or between 250 mm / s and 700 mm / s, such as, for example, 300 mm / s. Moreover, the total flow of gas and air mixture can be between 200 liters per minute (L / min) and 750 L / min, or 450 L / min.

[0039] The temperature reached on the surface being treated during treatment with a flame of a gas including propane, can be between 30°C and 90°C, for example, between 50 °C and 80 °C, or between 60 °C and 65 °C; for example, 60°C. At temperatures below 30°C and above 90°C, the desired increase in surface energy, increase of the polar part of the surface energy and increase wettability of the surface being treated is not obtained, or the surface is over-treated. The surface energy of the flame- treated surface can be greater than 30 millinewtons per meter (mN / m), and the polar part of the surface energy is greater than 1 .5 mN / m, for example, greater than 2 mN / m.

[0040] Activation of a surface being treated can be characterized by quantifying the changes on surface free energy and wettability. SFE quantifies the disruption of intermolecular bonds that occur when a surface is created. SFE is the energy required to increase the size of the surface of a phase. It can be considered as having a polar and a disperse (or dispersive) part. Wettability is the ability of a liquid (e.g., water) to maintain contact with a solid surface. Wettability is generally determined by measuring the contact angle of water with a surface.

[0041] After surface activation, the polyolefin can achieve a surface chemistry that is favorable for further secondary operations and does not have a detrimental effect on long-term adhesion or on the original properties of the polyolefin. Creating a specific surface chemistry on the polyolefin can aid with achieving strong initial and long-term adhesion of adhesive systems, for long life expectancy and safety of automotive parts in real environment conditions.

[0042] The surface can also be activated using a different activation method, by treating said surface with e.g., atmospheric plasma, low pressure plasma, with a coronatreatment or by fluorination.

[0043] Primer

[0044] A primer, also known as an adhesion promoter, is a preparatory coating that is applied onto a bonding surface before contacting the surface with a bonding agent or base coat, to improve adhesion of the bonding agent or base coat to the bonding surface.

[0045] The primer can be a synthetic resin dispersion, e.g., a waterborne primer or solvent born primer. The primer can be one or two components and can be based on polyurethane, acrylic, epoxy or polyester chemistry. The primer can include, for example, butylacetate, isocyanate, 2-(2-butoxyethoxy)ethanol, hydrocarbons, hexamethylene, 2-butoxy ethanol, ethoxy propanol, hexamethylene, diisocyanate, or a combination thereof.

[0046] The primer can be colored, black, or transparent. As noted herein, the polyolefin can be translucent and the primer can be transparent and areas of the polyolefin can be backlit, e.g., exposing a lighting feature located behind the polyolefin part. A thickness of the primer can be, for example, 2 micrometers (pm) to 50 pm, 10 pm to 40 pm, or 15 pm to 30 pm.

[0047] As used herein, unless specified otherwise, “transparent” can refer to a material property comprising at least one of: a visible light transmission equal to or greater than 40%; and a haze equal or greater than 60 %. The primer can have a transparency of 40 to 100%.

[0048] Base coat

[0049] The basecoat can be a synthetic resin, e.g., waterborne. The basecoat can include, for example, butan-1-ol, 2-(2-butoxyethoxy)ethanol, propan-2-ol, and 2-dimethylaminoethanol.

[0050] The base coat can be any desired color. A thickness of the base coat can be, for example, 5 pm to 50 pm, 10 pm to 40 pm, or 10 pm to 20 pm.

[0051] Base coat removal

[0052] Areas for lighting are removed by laser etching, e.g., ablation, of the base coat, retaining primer thereunder. Laser conditions can include, for example, use of an infrared laser, having a wavelength of 1 ,064 nanometers, optic type f 450 for coating ablation in day / night processing mode. Primer would be retained on the polyolefin in the areas etched, e.g., ablated, by laser. Primer, e.g., transparent primer, exhibits desirable adhesion to a final clear coat without further surface treatment, e.g., activation, of polyolefin. A minimal amount of primer should be removed with the base coat, for example, 0.01 pm to 6 pm, 0.1 pm to 5 pm, or 1 pm to 4 pm. A thickness of the primer retained after removal of the base coat can be, for example, greater than or equal to 1 pm, 1 pm to 50 pm, 10 pm to 40 pm, or 15 pm to 30 pm. The retained thickness of primer can ensure good adhesion of a clear coat without surface activation with flame or plasma.

[0053] Clear coat

[0054] The clear coat includes a transparent polymer. Any suitable transparent polymer can be used. Examples include, but are not limited to, an acrylic monomer, an epoxy, a polyurethane, a polysiloxane or a combination thereof.

[0055] The clear coat can include a silicone, a polyurethane, an acrylate, a metal oxide, or a combination thereof. The clear coat can include a silicone. The clear coat can be one or two components.

[0056] The clear coat can provide, for example, scratch resistance, ultraviolet (UV) resistance, or a combination thereof. The clear coat can help render the polyolefin part suitable for environmental exposure. A thickness of the clear coat can be, for example, 5 pm to 50 pm, for example, 25 pm to 45 pm, or 30 pm to 45 pm.

[0057] The polyolefin part, as disclosed herein, can be translucent and used to integrate lighting, functional features, ornamental elements, or a combination thereof into an assembly, e.g., of a front cover of a vehicle, for example, an electric vehicle.

[0058] The translucent polyolefin part can be transparent. Translucency is a superset of transparency. A translucent medium allows the transport of light while a transparent medium not only allows the transport of light but also allows for image formation. As such, a transparent medium is also translucent, but a translucent medium can be transparent, but is not necessarily so. Opacity is the opposite of translucency.

[0059] The translucent polyolefin can have a transmittance of visible light above 10%. Opaque is defined as having a visible light transmittance of up to 10%. The transparent portion is optically transparent, i.e. it is transparent to at least light visible to the human eye, and can have a transmittance of visible light above 30%.

[0060] The assembly can further include a light module. The translucent polyolefin part can form part of the light module, such as a light emitting diode (LED) light module. The light module can include a reflector and a lighting member. The invention also relates to a vehicle, e.g., an electric vehicle, including an assembly as described herein. The assembly can form part of a front fascia of the vehicle, where fascia is a general term for a set of front-end components of the vehicle. The assembly can be part of the front fascia of the vehicle. The assembly can replace the grille of the vehicle. A pair of headlights can flank the assembly. The assembly can be placed between the headlights of the vehicle. The front panel assembly can extend between a bumper fascia and a front window of the vehicle. The assembly can be adjacent to the bumper fascia, e.g., a covering of the bumper beam, and can further extend over the front of the vehicle up to a lower edge of the front window of the vehicle.

[0061] The clear coat can be present directly on the exposed primer in an area corresponding to a sensor accommodating portion, a light accommodating portion, a camera accommodating portion, a display accommodating portion, a receiver accommodating portion, a transmitter accommodating portion, or a combination thereof.

[0062] The invention is now elucidated by way of the following examples, without however being limited thereto.

[0063] Examples

[0064] The following examples are intended to explain the invention, not to limit the invention.

[0065] A translucent polypropylene plaque (145 x 210 millimeters, thickness 3.2 millimeters (mm)) was formed by injection molding. The plaque was coated with primer (thickness 19 to 22 micrometers (pm)) and a black base coat (thickness 16 to 19 pm).

[0066] An area (e.g., of 7 x 3 centimeters (cm)) top black base coat was removed by laser ablation (infrared laser, having a wavelength of 1 ,064 nanometers, optic type f 450 for coating ablation in day / night processing mode) to a cleanness level that black color was not visible on the surface and with minimal removal of primer layer underneath. Analysis of the samples was conducted by microscope in cross-section. A line between the polypropylene and primer was clearly visible in the cross-section. No black base coat residue was visible on the surface in the ablated area using a light microscope. Measurements were taken at various locations on the sample, with a summary provided in Table 1.

[0067] Table 1

[0068] The results indicated that approximately 17 pm thickness base coat can be fully removed by laser ablation without any visible residue. Only a few micrometers of primer underneath the base coat is removed during laser ablation. A thickness of primer of greater than 16 pm of primer is still present after laser ablation.

[0069] The term “automotive” or “automobile(s)” or “vehicle(s)” or other similar term as used herein is inclusive of motor vehicles in general such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g., fuels derived from resources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle that has two or more sources of power, for example, both gasoline-powered and electric-powered vehicles.

[0070] The compositions, methods, and articles can alternatively comprise, consist of, or consist essentially of, any appropriate components or steps herein disclosed. The compositions, methods, and articles can additionally, or alternatively, be formulated so as to be devoid, or substantially free, of any steps, components, materials, ingredients, adjuvants, or species that are otherwise not necessary to the achievement of the function or objectives of the compositions, methods, and articles.

[0071] The singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. “Or” means “and / or” unless clearly indicated otherwise by context. The terms “front”, “back”, “bottom”, or “top” are used herein, unless otherwise noted, merely for convenience of description, and are not limited to any one position or spatial orientation. The terms “first,” “second,” and the like, “primary,” “secondary,” and the like, as used herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another.

[0072] The endpoints of all ranges directed to the same component or property are inclusive and independently combinable (e.g., ranges of “less than or equal to 25 wt %, or 5 wt % to 20 wt %,” is inclusive of the endpoints and all intermediate values of the ranges of “5 wt % to 25 wt %,” etc.). Disclosure of a narrower range or more specific group in addition to a broader range is not a disclaimer of the broader range or larger group.

[0073] The suffix “(s)” is intended to include both the singular and the plural of the term that it modifies, thereby including at least one of that term (e.g., the colorant(s) includes at least one colorants). “Optional” or “optionally” means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where the event occurs and instances where it does not. Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this disclosure belongs. A “combination” is inclusive of blends, mixtures, alloys, reaction products, and the like.

[0074] All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if a term in the present application contradicts or conflicts with a term in the incorporated reference, the term from the present application takes precedence over the conflicting term from the incorporated reference.

[0075] While typical embodiments have been set forth for the purpose of illustration, the foregoing descriptions should not be deemed to be a limitation on the scope herein. Accordingly, various modifications, adaptations, and alternatives can occur to one skilled in the art without departing from the spirit and scope herein.

Claims

WHAT IS CLAIMED IS:

1. A process for producing a polyolefin part comprising: treating a surface of the polyolefin part to provide an activated polyolefin surface; applying a primer directly on the activated polyolefin surface; applying a base coat directly on the primer; removing a portion of the base coat by laser etching while retaining at least a portion of the primer present between the base coat and the activated polyolefin surface; and applying a clear coat directly on remaining base coat and exposed primer.

2. The process of claim 1 , wherein treating the surface of the polyolefin comprises treating with a flame or plasma.

3. The process of claim 1 or 2, wherein treating the surface of the polyolefin comprises treating with a flame of a propane-comprising gas, said propane-comprising gas being propane or a mixture comprising at least 50 wt. % of propane based on a weight of the propane-comprising gas with methane, ethane, butane, pentane, hexane, or a combination thereof, wherein, during treatment with the flame of the propane-comprising gas, a flame is produced by burning a mixture of air and the propane-comprising gas, wherein the gas-to-air ratio is chosen such that the propane gas to oxygen volume ratio is equal to or less than 1 :5.01 .

4. The process of any of the preceding claims, wherein the polyolefin comprises polypropylene.

5. The process of any of the preceding claims, wherein the polyolefin has a haze of 73 to 100% and transmittance of 40 to 70%.

6. The process of any of the preceding claims, wherein the primer has a transparency of 40 to 100%.

7. The process of claim 6, wherein the primer comprises 2-2-butoxyethoxy)ethanol.

8. The process of any of the preceding claims, wherein the base coat comprises butan-1-ol, 2-(2-butoxyethoxy)ethanol, propan-2-ol, and 2-dimethylaminoethanol.

9. The process of any of the preceding claims, wherein all of the primer present between the base coat and the activated polyolefin surface is retained.

10. The process of any of claims 1 to 8, wherein a thickness of greater than or equal to 1 micrometers of the primer present between the base coat and the activated polyolefin surface is retained.11 . The process of any of the preceding claims, wherein the clear coat comprises an acrylic monomer, an epoxy, a polyurethane, a polysiloxane or a combination thereof.

12. A polyolefin part prepared by the process of any of the preceding claims.

13. The polyolefin part of claim 12, wherein the clear coat is present directly on the exposed primer in an area corresponding to a sensor accommodating portion, a light accommodating portion, a camera accommodating portion, a display accommodating portion, a receiver accommodating portion, a transmitter accommodating portion, or a combination thereof.

14. The polyolefin part of claim 12, wherein the polyolefin part is a vehicle part.

15. A vehicle comprising the polyolefin part of claim 13.

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