Metallizable thermoplastic compositions and applications thereof

Abstract

Disclosed are metallizable thermoplastic compositions that include at least polypropylene, an ethylene based alpha-olefin elastomer, an inorganic filler, and one or more polar polymers. Also disclosed are methods that include etching a surface of a thermoplastic comprising such a metallizable thermoplastic composition and bonding a metal layer to the thermoplastic (after etching the surface of the thermoplastic). Also disclosed are articles comprising the metallized thermoplastic.

Description

METALLIZABLE THERMOPLASTIC COMPOSITIONS AND APPLICATIONSTHEREOFCROSS REFERENCE TO RELATED APPLICATIONS

[0001] None.FIELD

[0002] The present disclosure generally relates to compounds that comprise propylene (polypropylene compounds). More specifically, the present disclosure relates to metallizable polypropylene compounds, metallizing polypropylene compounds, and metallized articles thereof.BACKGROUND

[0003] In recent years, manufacturers have increased the use of metallized plastic components in a variety of products. For example, metallized polymer components are used in electrical and electronic (E&E) devices, automotive components, computer body parts, office equipment, machinery, appliances, furniture and packaging. Typically, metal deposition on plastic surfaces is accomplished by techniques such as electroless plating, electroplating, and the like. Key challenges in electroless plating of plastic’s polymer surface is creating a strong and durable adhesion between metal and the polymer, as they have properties that make them inherently incompatible with each other; for example, they have disparate surface energies and coefficient of thermal expansions (CTEs). Generally, to promote a strong adhesion of metal to a polymer surface, chemical and / or surface morphological changes have to be made to the surface of the polymer substrate.

[0004] The conventional procedure used to make changes to the surface of the polymer substrate involves etching the polymer surface with strong oxidizing solutions such as hexachrome sulfuric acid or acidified potassium permanganate, prior to the electroless plating. This etching step results in (i) the formation of nano / micro-pores that allow the anchoring / nucleation of metal particles and / or the mechanical interlocking and / or (ii) the creation of polar groups suchas hydroxyl, carbonyl, and carboxyl groups on the polymer surface. The efficiency of such etching step has been widely proven for certain thermoplastic polymers such as acrylonitrilebutadiene- styrene copolymer (ABS). In the ABS matrix, the butadiene (BD) domains are uniformly dispersed within the styrene acrylonitrile (SAN) in which the double bond of butadiene will get selectively etched with oxidizing agents leading to the formation of microcavities and polar groups. On the other hand, in the case of hydrophobic thermoplastic polymers such as polypropylene (PP), the above etching step is generally not effective.

[0005] It appears that several approaches have been explored to improve the adhesion of metal onto polypropylene substrates. For example, pre-treatments such as flame treatment, corona discharge treatment, plasma treatment, grafting of glycidyl methacrylate, and grafting of maleic anhydride have been suggested to enhance the adhesion of metal onto a substrate. Melt blending of chelating monomers such as methacrylate, maleimide, and metal-bonding groups in diketone and aspartic acid have also been used with polypropylene to functionalize the polymer and enhance the metal adhesion. Low polarity rubber, and homopolymer or copolymer ethylene, mineral additives and carbon black have also been used to enhance the adhesion of metal onto polypropylene.BRIEF SUMMARY

[0006] There is a need for polypropylene compounds that are amenable to metallization with standard electroless plating and electroplating processes. The present thermoplastic polypropylene compounds are amenable to etching as a result of polar polymers included in them.

[0007] Some configurations of the disclosure include a metallizable thermoplastic composition that comprises polypropylene, an ethylene based alpha-olefin elastomer, an inorganic filler, and one or more polar polymers.

[0008] Some configurations of the disclosure include a method that comprises etching a surface of a thermoplastic, where the thermoplastic comprises a metallizable thermoplastic composition that comprises polypropylene, an ethylene based alpha-olefin elastomer, aninorganic filler, and one or more polar polymers. The method further comprises bonding a metal layer to the thermoplastic (after etching the surface of the thermoplastic).

[0009] Some configurations of the disclosure include a metallized article that comprises a metal layer bonded to thermoplastic, where the thermoplastic comprises a metallizable thermoplastic composition that comprises polypropylene, an ethylene based alpha-olefin elastomer, an inorganic filler, and one or more polar polymers.

[0010] The following includes definitions of various terms and phrases used throughout this specification.

[0011] The terms “domain” size or “pore” size, as used herein, refer to a size of a site, a pore, or a cavity that has been formed / created within a surface of a thermoplastic composition as a result of an etching process.

[0012] The terms “about” or “approximately” are defined as being close to as understood by one of ordinary skill in the art. In one non-limiting aspect the terms are defined to be within 10%, preferably, within 5%, more preferably, within 1%, and most preferably, within 0.5%.

[0013] For the purposes of this disclosure, “X, Y, and / or Z” can be construed as X only, Y only, Z only, or any combination of two or more items X, Y, and Z (e.g., XYZ, XY, XZ, YZ).

[0014] The terms “wt. %”, “vol. %” or “mol. %” refer to a weight, volume, or molar percentage of a component, respectively, based on the total weight, the total volume, or the total moles of material that includes the component. In a non-limiting example, 10 moles of component in 100 moles of the material is 10 mol. % of component.

[0015] The term “substantially” and its variations are defined to include ranges within 10%, within 5%, within 1%, or within 0.5%.

[0016] The terms “inhibiting” or “reducing” or “preventing” or “avoiding” or any variation of these terms, when used in the claims and / or the specification, include any measurable decrease or complete inhibition to achieve a desired result.

[0017] The term “effective,” as that term is used in the specification and / or claims, means adequate to accomplish a desired, expected, or intended result.

[0018] The use of the words “a” or “an” when used in conjunction with the term “comprising,” “including,” “containing,” or “having” in the claims or the specification may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.”

[0019] The words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”) or “containing” (and any form of containing, such as “contains” and “contain”) are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

[0020] The process of the present invention can “comprise,” “consist essentially of,” or “consist of’ particular ingredients, components, compositions, etc., disclosed throughout the specification.

[0021] The term “primarily,” as that term is used in the specification and / or claims, means greater than any of 50 wt. %, 50 mol. %, and 50 vol. %. For example, “primarily” may include 50.1 wt. % to 100 wt. % and all values and ranges there between, 50.1 mol.% to 100 mol.% and all values and ranges there between, or 50.1 vol. % to 100 vol. % and all values and ranges there between.

[0022] Other objects, features and advantages of the present disclosure will become apparent from the following figures, detailed description, and examples. It should be understood, however, that the figures, detailed description, and examples, while indicating specific embodiments of the disclosure, are given by way of illustration only and are not meant to be limiting. Additionally, it is contemplated that changes and modifications within the spirit and scope of the disclosure will become apparent to those skilled in the art from this detailed description. In further embodiments, features from specific embodiments may be combined with features from other embodiments. For example, features from one embodiment may becombined with features from any of the other embodiments. In further embodiments, additional features may be added to the specific embodiments described herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0023] For a more complete understanding, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

[0024] FIG. 1 depicts a conceptual flowchart of an example of the present methods of preparing polypropylene compounds for metallization of such compounds.

[0025] FIG. 2 depicts a scanning electron microscope (SEM) image of an un-etched plaque made via a method that utilized one example formulation (“F1C” as shown in Table 1).

[0026] FIG. 3 depicts an SEM image of an etched plaque made via a method that utilized the example formulation that was utilized in FIG. 2 (“F1C”), which subsequently resulted in incomplete metal coating coverage (about 90% to 95% based on visual inspection, as shown in Table 2).

[0027] FIG. 4 depicts an SEM image of an un-etched plaque made via a method that utilized another example formulation (“F2C” as shown in Table 1).

[0028] FIG. 5 depicts an SEM image of an etched plaque made via a method that utilized the example formulation that was utilized in FIG. 4 (“F2C”), which subsequently resulted in incomplete metal coating coverage (about 30% to 90% based on visual inspection, as shown in Table 2).

[0029] FIG. 6 depicts an optical image (converted from a color image to a grayscale image) of an electroplated plaque made via a method that utilized a formulation (“Fl A” as shown in Table 1) that did not include one or more polar polymers and resulted in incomplete metal coating coverage.

[0030] FIG. 7 depicts an optical image (converted from a color image to a grayscale image) of an electroplated plaque made via a method that utilized a formulation (“FIB” asshown in Table 1) that did not include one or more polar polymers and also resulted in incomplete metal coating coverage.

[0031] FIG. 8A depicts an optical image (converted from a color image to a grayscale image) of an electroplated plaque made via a method that utilized a formulation (“F3” as shown in Table 1) that did not include one or more polar polymers and also resulted in incomplete metal coating coverage (about 90% to 95% based on visual inspection, as shown in Table 2).

[0032] FIG. 8B depicts an SEM image of an etched plaque made via a method that utilized the same formulation that was utilized in FIG. 8A (“F3”).

[0033] FIG. 9A depicts an optical image (converted from a color image to a grayscale image) of an electroplated plaque made via a method that utilized an example of a metallizable thermoplastic composition of the present disclosure (“F6” as shown in Table 1) that include one or more polar polymers and also resulted in complete metal coverage (100% based on visual inspection, as shown in Table 2).

[0034] FIG. 9B depicts an SEM image of an etched plaque made via a method that utilized the example of the metallizable thermoplastic composition of the present disclosure (“F6” as shown in Table 1) as was utilized in FIG. 9A.

[0035] FIG. 10 is a flowchart depicting an example of a method that includes etching a surface of a thermoplastic (where the thermoplastic comprises a metallizable thermoplastic composition according to the present disclosure) and bonding a metal layer to the thermoplastic after etching the surface of the thermoplastic (e.g., to form a metallized thermoplastic article), according to one embodiment.DETAILED DESCRIPTION

[0036] In implementations of this disclosure, polypropylene (PP) may be melt blended with a mixture of synergistic additives for improved adhesion with a metal layer. Specifically, PP may be melt blended with an ethylene based alpha-olefin elastomer, an inorganic filler, and one or more polar polymers (also referred to herein as “polar resinous additives”) to improve itsadhesion with metal layer. An optimal loading of one or more of these synergistic additives can result in PP compositions (also referred to herein as “metallizable thermoplastic compositions”) that exhibit uniform and complete surface coverage of the metal layer and high metal adhesion while retaining other mechanical, thermal and electrical properties that are satisfactory for a particular target application.

[0037] Examples of an ethylene based alpha-olefin elastomer may include a C4-C10 alpha-olefin, such as an ethyl ene-butene based elastomer or an ethylene-octene based elastomer. Illustrative, non-limiting examples of such polyolefin elastomers (also referred to herein as “POEs”) may include: FORTIFY C5070T (SABIC); FORTIFY B0563T (SABIC); FORTIFY B4572T (SABIC); and / or Tafrner DF 605 (Mistui Chemicals, Inc.). Examples of inorganic fillers (e.g., reinforcing fillers) may include one or more of the following: aluminum oxide, zinc oxide, titanium dioxide, zirconium oxide, calcium carbonate, talc, silica, glass beads, hollow glass beads, glass fibers (e.g., short glass fibers (“SGF”) and / or long glass fibers (“LGF)), aluminum oxide fibers, carbon fibers, and graphene. Examples of polar polymers may include: poly(vinyl) alcohol (“PVOH”), ethylene vinyl alcohol (“EVOH”), polyvinylpyrrolidone, polypropylene acrylic acid, polyethylene acrylic acid, polypropylene acrylate, polyethylene acrylate, polypropylene methacrylate, polyethylene methacrylate, polyacrylic acid, polymethacrylic acid, polyacrylate, polymethacrylate, and ionomers. In some aspects, a percentage of polar groups in the polar polymer(s) may be in a range of 5% to 100%.

[0038] Polyolefin elastomers such as FORTIFY C5070T, FORTIFY B0563T and Tafrner DF 605 have lower density values of 870kg / m3, 860kg / m3and 860kg / m3, respectively, compared to the PP (905kg / m3). The lower density values of these POEs indicates that these POEs are comparatively amorphous to the PP. As such, the inventors expect that incorporation of these amorphous POEs into PP may alter the crystalline morphology of PP (apart from increasing the overall amorphous content). The amorphous portion is more amenable for etching upon exposure to oxidizing etching solutions such as chromo-sulfuric acid or manganese based etching solutions. The melt-flow index (“MFI”) of the POEs may play a significant role in controlling the “domain” size of sites, pores, or cavities that are formed / created within the surface of the corresponding POEs in the PP matrix. Selection of a POE (e.g., with an appropriate number ofcarbon atoms) that has a satisfactory MFI may allow for the creation of micro / nano pores with appropriate dimensions for improving the metal adhesion strength on the surface of the PP- composition based article.

[0039] The inventors also expect that the incorporation of “incompatible” polar additives (such as PVOH, EVOH, ionomers, etc.) into PP may increase surface polarity (due to preferential migration of these additives to the surface) during the injection molding process, thereby enabling surface wetting when a part is immersed into the etching solution and / or facile etching at the surface. The inventors expect that such an etching may lead to the creation of micro / nano cavities in order to improve mechanical anchoring of metal atoms / molecules during a subsequent electroless plating and / or electroplating process, thereby enhancing the adhesion strength of metal onto the PP surface. Inorganic filler additives (e.g., aluminum oxide, zinc oxide, titanium dioxide, zirconium oxide, calcium carbonate, talc, silica, glass beads, hollow glass beads, glass fibers (e.g., “SGF” or “LGF”), aluminum oxide fibers, carbon fibers, and graphene) may be utilized along with the aforementioned adhesion promoting additives to provide improved mechanical, thermal and electrical properties (e.g., shrink rate, stiffness, HDT, impact and CTE) satisfactory for a particular end-use application. Such inorganic filler additives may also advantageously have ancillary improvements with respect to metal plating adhesion.

[0040] The thermoplastic polypropylene compounds of the present disclosure can be made by various methods known in the art. For example, components such as polypropylene, an ethylene based alpha-olefin elastomer, inorganic / reinforcing filler(s), polar polymer(s), and (optional) additive(s), can be mixed together and then melt-blended to form the polypropylene compound (also referred to herein as a “metallizable thermoplastic composition”). The melt blending of the components can include use of shear force, extensional force, compressive force, ultrasonic energy, electromagnetic energy, thermal energy or combinations comprising at least one of the foregoing forces or forms of energy.

[0041] In some aspects, one or any foregoing components described herein may be first blended such as dry blended with each other such as by hand mixing or in a high-speed mixer. The blend can then be fed into the throat of a twin-screw extruder via a hopper. In some aspects,at least one of the components can be incorporated by feeding the component directly into the extruder at the throat and / or downstream through a side feeder, or by being compounded into a master batch with polypropylene and fed into the extruder. The extruders used in the present disclosure may have a single screw, multiple screws, intermeshing co-rotating or counter rotating screws, non-intermeshing co-rotating or counter rotating screws, reciprocating screws, screws with pins, screws with screens, barrels with pins, rolls, rams, helical rotors, co-kneaders, discpack processors, various other types of extrusion equipment, or combinations comprising at least one of the foregoing. The extruder can generally be operated at a temperature higher than that necessary to cause the composition to melt and flow. In some aspects, the temperature of the melt in the extruder barrel can be maintained as low as possible in order to avoid excessive thermal degradation of the components. In some aspects, antioxidants (e.g. Irgaphos-168 and Irganox 1010 from BASF) may be added during the extrusion process to avoid oxidative thermal degradation of the polymeric components. In some aspects, coupling agents (e.g. PO1020 from Exxelor™) may be added during the extrusion process to enhance the compatibility of glass fibers with the PP. In some aspects, nucleating agents (e.g. talc) may be added during the extrusion process to accelerate the nucleation of PP. The melted compound exits the extruder through small exit holes in a die. The extrudate can be quenched in a water bath and pelletized. The pellets so prepared can be of any desired length (e.g., one-fourth inch long or less). Such pellets can be used for subsequent molding (e.g., injection molding, compressive molding, etc.), shaping, or forming.

[0042] Mixtures including any combination of the foregoing mentioned components can be subjected to multiple blending and forming steps if desirable. For example, the thermoplastic polypropylene compound may first be extruded and formed into pellets. The pellets may then be fed into a molding machine where it may be formed into any desirable shape or product. In some aspects, the thermoplastic polypropylene compound emanating from a single melt blender may be formed into sheets or strands and subjected to post-extrusion processes, such as annealing, uniaxial orientation, or biaxial orientation.

[0043] Shaped, formed, casted, or molded articles comprising the thermoplastic polypropylene compounds are also provided. The thermoplastic polypropylene compounds canbe molded into useful shaped articles by a variety of methods, such as injection molding, compression molding, extrusion, rotational molding, blow molding, 3D printing, additive manufacturing and thermoforming. The article can be a molded article, a thermoformed article, an extruded film, an extruded sheet, a honeycomb structure, one or more layers of a multi-layer article, a substrate for a coated article, and a substrate for a metallized article (e.g., an article that includes the thermoplastic polypropylene compound coated with a metal layer).

[0044] Referring to FIG. 1, aspects of the disclosure include a method 100 of metallizing a polypropylene composition. As shown in FIG. 1, the method 100 includes, at block 110, meltblending of polypropylene with a plurality of components including at least an ethylene based alpha-olefin elastomer, an inorganic filler, and one or more polar polymers to form a metallizable thermoplastic composition.

[0045] In some configurations, the ethylene based alpha-olefin elastomer that is melt- blended and thereby comprised in the metallizable thermoplastic composition comprises a C4-C10 alpha-olefin, such as an ethyl ene-butene based elastomer or an ethylene-octene based elastomer. In some configurations, the metallizable thermoplastic composition comprises 10 wt. % to 30 wt. % or any range therein, including 10 wt. % to 15 wt. %, 15 wt. % to 20 wt. %, 20 wt. % to 25 wt. %, 25 wt. % to 30 wt. %, 10 wt. % to 20 wt. %, and 10 wt. % to 25 wt. % of the ethylene based alpha-olefin elastomer.

[0046] In some configurations, the polar polymer(s) that are melt-blended and thereby comprised in the metallizable thermoplastic composition can be one or more of poly(vinyl) alcohol (“PVOH”), ethylene vinyl alcohol (“EVOH”), polyvinylpyrrolidone, polypropylene acrylic acid, polyethylene acrylic acid, polypropylene acrylate, polyethylene acrylate, polypropylene methacrylate, polyethylene methacrylate, polyacrylic acid, polymethacrylic acid, polyacrylate, polymethacrylate, and ionomers. In some configurations, the metallizable thermoplastic composition comprises 2 wt. % to 25 wt. % or any range therein, including 2 wt. % to 5 wt. %, 5 wt. % to 10 wt. %, 10 wt. % to 15 wt. %, 15 wt. % to 20 wt. %, 20 wt. % to 25 wt. %, 2 wt. % to 20 wt. %, and 5 wt. % to 20 wt. % of the one or more polar polymers. In some configurations, the metallizable thermoplastic composition comprises one or more polarpolymers where the percentage of polar groups in the one or more polar polymers is in a range of 5% to 100%, or any range therein, including 5% to 10%, 10% to 15%, 15% to 20%, 20% to 25%, 25% to 30%, 30% to 35%, 35% to 40%, 40% to 45%, 45% to 50%, 50% to 55%, 55% to 60%, 60% to 65%, 65% to 70%, 70% to 75%, 75% to 80%, 80% to 85%, 85% to 90%, 90% to 95%, 95% to 100%, 10% to 95%, 15% to 90%, 20% to 85%, 25% to 80%, 30% to 75%, 35% to 70%, 40% to 75%, 45% to 70%, and 50% to 65%. The percentage of polar groups in the polar copolymer indicates the weight percentage of polar comonomer present in the copolymer.

[0047] In some configurations, the inorganic fillers / additives that are melt-blended and thereby comprised in the metallizable thermoplastic composition can be one or more aluminum oxide, zinc oxide, titanium dioxide, zirconium oxide, calcium carbonate, talc, silica, glass beads, hollow glass beads, glass fibers, aluminum oxide fibers, carbon fibers, and graphene. The meltblending can be carried out in an extruder or in a melt blender. In some configurations, the metallizable thermoplastic composition comprises 10 wt. % to 40 wt. % or any range therein, including 5 wt. % to 10 wt. %, 10 wt. % to 15 wt. %, 15 wt. % to 20 wt. %, 20 wt. % to 25 wt. %, 25 wt. % to 30 wt. %, 30 wt. % to 35 wt. %, 35 wt. % to 40 wt. %, 10 wt. % to 30 wt. %, and 15 wt. % to 25 wt. % of the inorganic filler.

[0048] In some configurations, the metallizable thermoplastic composition comprises 40 wt. % to 76 wt. %, or any range therein, including 40 wt. % to 45 wt. %, 45 wt. % to 50 wt. %, 50 wt. % to 55 wt. %, 55 wt. % to 60 wt. %, 60 wt. % to 65 wt. %, 65 wt. % to 70 wt. %, 70 wt. % to 76 wt. %, 35 wt. % to 65 wt. %, 40 wt. % to 60 wt. %, 45 wt. % to 55 wt. %, and 50 wt. % to 53 wt. % of polypropylene. In some aspects, the metallizable thermoplastic composition comprises 40 wt. % to 76 wt. % of polypropylene, along with 2 wt. % of processing additives comprising: 0.1 wt. % of antioxidant (for example, Irganox-1010), 0.1 wt. % of heat stabilizer (for example, Irgafos-168), 0.2 wt. % of nucleating agent (for example, talc), and 1.6 wt. % of coupling agent (for example, maleic anhydride functionalized polypropylene such as Exxelor™ P0 1020).

[0049] In the depicted example, block 120 includes etching a surface of a thermoplastic(comprising the metallizable thermoplastic composition) with an oxidizing agent. The oxidizingagent can include any of hexa-chrome sulfuric acid (HCSA), tri-chrome, potassium permanganate, manganese-based etching solutions, or any combination thereof. In some configurations, the etching of the surface, at block 120, is carried out at a temperature of 25°C to 80°C and any range therein, including 25°C to 30°C, 30°C to 35°C, 35°C to 40°C, 40°C to 45°C, 45°C to 50°C, 50°C to 55°C, 55°C to 60°C, 60°C to 65°C, 65°C to 70°C, 70°C to 75°C, 75°C to 80°C, 30°C to 75°C, 35°C to 70°C, 40°C to 65°C, and 45°C to 60°C for a period in a range of 1 to 30 minutes and any range therein, including 1 to 5 minutes, 5 to 10 minutes, 10 to 15 minutes, 12 to 15 minutes, 15 to 20 minutes, 20 to 25 minutes, 25 to 30 minutes, 5 to 15 minutes, 10 to 20 minutes, 15 to 25 minutes, and 20 to 30 minutes.

[0050] In the depicted example, block 130 involves bonding a metal layer to the etched surface of the thermoplastic. In some configurations, the bonding of the metal layer to the thermoplastic polypropylene compound includes an electroless process. In other configurations, the bonding of one or more metal layers includes one or more initial electroless plating processes (e.g., palladium, copper, nickel, silver, tin, etc.) followed by one or more electroplating processes (e.g., one or more of various metals). According to some aspects, in the electroplating process(es), an etched surface is exposed to a palladium / tin bath or a silver / tin bath such that the metal(s) are deposited in initial active sites in order to facilitate subsequent electroplating.

[0051] One suitable measure of the success of bonding between the metal layer and the etched surface of the thermoplastic is by measuring the peel strength, where the greater the peel strength the better is the adherence of the metal on the thermoplastic polypropylene compound. In some configurations, the peel strength of the bond between the metal layer and the etched surface of the thermoplastic is >0.3 N / mm, or any range therein, including 0.3 N / mm to 3 N / mm, 0.5 N / mm to 3 N / mm, 0.6 N / mm to 3 N / mm, 0.7 N / mm to 3 N / mm, 0.8 N / mm to 3 N / mm, 0.9 N / mm to 3 N / mm, 1.0 N / mm to 3.0 N / mm, 1.1 N / mm to 3 N / mm, 1.2 N / mm to 3 N / mm, 1.3 N / mm to 3 N / mm, 1.4 N / mm to 3 N / mm, 1.5 N / mm to 3 N / mm, 1.6 N / mm to 3 N / mm, 1.7 N / mm to 3.0 N / mm, 1.8 N / mm to 3 N / mm, 1.9 N / mm to 3 N / mm, 2.0 N / mm to 3 N / mm, 0.5 N / mm to 2.5 N / mm, 0.6 N / mm to 2.5 N / mm, 0.7 N / mm to 2.5 N / mm, 0.8 N / mm to 2.5 N / mm, 0.9 N / mm to 2.5 N / mm, 1.0 N / mm to 2.5 N / mm, 1.1 N / mm to 2.5 N / mm, 1.2 N / mm to 2.5 N / mm, 1.3 N / mm to 2.5 N / mm, 1.4 N / mm to 2.5 N / mm, 1.5 N / mm to 2.5 N / mm, 1.6 N / mm to2.5 N / mm, 1.7 N / mm to 2.5 N / mm, 1.8 N / mm to 2.5 N / mm, 1.9 N / mm to 2.5 N / mm, and 2.0 N / mm to 2.5 N / mm.

[0052] The metallized thermoplastic compositions disclosed herein can be used to make a metallized thermoplastic article such as plurality of different components in one or more of the following: a component used in an electrical or electronic device, a component of a telecommunication device, radio-frequency (RF) filter, EMI shielding, wave-guide, antenna substrate, frequency selective surface, components of appliances, furniture, packaging, automotive interior components, automotive exterior components, badges, name plates, trims, electrical vehicle battery cover, and thermal management component.

[0053] Although aspects of the present invention have been described with reference to blocks of FIG. 1 should be appreciated that operation of the present invention is not limited to the particular blocks and / or the particular order of the blocks illustrated in FIG. 1. Accordingly, aspects of the invention may provide functionality as described herein using various blocks in a sequence different than that of FIG. 1.

[0054] The systems and processes described herein can also include various equipment that is not shown and is known to one of skill in the art of chemical processing. For example, some controllers, piping, computers, valves, pumps, heaters, thermocouples, pressure indicators, mixers, heat exchangers, and the like may not be shown.

[0055] As part of the disclosure of the present invention, specific examples are included below. The examples are for illustrative purposes only and are not intended to limit the invention. Those of ordinary skill in the art will readily recognize parameters that can be changed or modified to yield essentially the same results.EXAMPLES Compositions

[0056] Table 1 illustrates several PP compositions (identified as: F0; F1A; FIB; F1C; F2A; F2B; F2C; F3; F4; F5; and F6) which are incorporated with different metal adhesionpromoting additives. These PP compositions were prepared by melt blending PP with different additives in a twin-screw extruder. Results of mechanical, thermal, density and metallization are shown in Table 2. As can be seen from Table 2, complete surface coverage was achieved in case of PP compositions F5 and F6.

[0057] The peel strength of several of these compositions were tested using the test method of ASTM B533-85, and the results obtained from such tests are shown in Table 2. No metal plating coverage or incomplete metal plating coverage was evident for the compositions F0, Fl A, and F2A. Incomplete metal plating coverage was evident for the compositions FIB, F2B, F3, and F4. The peel strength of selected compositions (with relatively good metal plating) were tested using the test method of ASTM B533-85, and Table 2 shows the results obtained from such tests for the selected compositions.

[0058] Table 2 shows a summary of various mechanical and thermal performance properties of the different polypropylene compositions, including: tensile modulus; tensile strength; impact strength; heat distortion temperature (HDT); coefficient of linear thermal expansion (CLTE); metal coating coverage / surface coverage of metal plating (visual); and peel strength. Table 2 shows that, with composition F0 as a reference, there is a decrease in tensile modulus and HDT in the case of composition F1C (PP with 25 wt. % Fortify C5070) and composition F2C (PP with 20 wt. % Tafmer DF 605).

[0059] On a relative basis, a high metal adhesion strength (or peel strength) was observed in case of F1C that contains 25 wt. % of FORTIFY C5070T. Scanning microscopy images of POE containing samples shows formation of nano / micro cavities upon exposure to hexa-chrome sulfuric acid treatment at 68°C to 69°C for 12 minutes that helps metal plating with uniform surface coverage and to improve metal adhesion strength.

[0060] FIG. 2 depicts a scanning electron microscope (SEM) image 200 of an un-etched plaque made via a method that utilized one example of a formulation (“F1C” as shown inTable 1). FIG. 3 depicts an SEM image 300 of an etched plaque made via a method that utilized the example formulation (i.e., “F1C” as was utilized in FIG. 2) that subsequently resulted inincomplete metal coating coverage (about 90% to 95% with “skip plating” based on visual inspection, as shown in Table 2 below).

[0061] FIG. 4 depicts an SEM image 400 of an un-etched plaque made via a method that utilized another example of a formulation (“F2C” as shown in Table 1). FIG. 5 depicts an SEM image of an etched plaque made via a method that utilized the other example formulation (i.e., “F2C” as was utilized in FIG. 4) that subsequently resulted in incomplete metal coating coverage (about 30% to 90% with “skip plating” based on visual inspection, as shown in Table 2 below).

[0062] The SEM images depicted in FIG. 3 and FIG. 5 clearly illustrate that larger size pores were created in case of the PP composition with Tafmer DF 605 (i.e., for “F2C” in FIG. 5) compared to the PP composition with Fortify C5070T (i.e., for “F1C” in FIG. 3). The inventors note that the MFI of Tafmer DF 605 is 0.5g / 10min, which is significantly lower than that of the MFI of FORTIFY C5070T (5g / 10min). Thus, the larger size pores in case of the plaque made from F2C PP compositions (as depicted in FIG. 5 relative to FIG. 3) may be attributed to the larger domain size of Tafmer DF 605 due to it lower MFI. Upon exposure to the oxidizing etching solution, FIG. 5 illustrates that the entire domain is etched away and hence creates larger size pores on the plaque surface, which is not favorable for high metal adhesion strength. On the other hand, having comparatively higher MFI value, the domain size of Fortify C5070T is much smaller and hence smaller size pores are created upon exposure to the etching solution, and which promotes high metal adhesion. It is anticipated that incorporating optimal loading of polar additives (e.g., polymer polymers, such as PVOH, EVOH, etc.), along with an optimal loading of POE, may improve the metal adhesion strength.

[0063] Additionally, as can be seen from Table 2, though high adhesion strength is achieved by using 25 wt. % of FORTIFY C5070T (e.g., composition “F3” with no polar polymers, such as PVOH or EVOH), the PP composition does not exhibit 100% surface coverage with the plated metal layer. On a relative basis, Table 2 illustrates that composition “F5” (that contains 5 wt. % of PVOH, but without FORTIFY C5070T) exhibits complete surface coverage with a reasonable adhesion strength. Optical images of the plated plaques of PPcompositions with different metal adhesion promoting additives are shown in FIG. 6 (“Fl A”), FIG. 7 (“FIB”), FIG. 8A (“F3”), and FIG. 9A (“F6”). Specifically, FIG. 6 depicts an optical image 600 (converted from a color image to a grayscale image) of a first example of an electroplated plaque made via a method that utilized formulation “Fl A” (see Table 1) that did not include any polar polymers and resulted in no coating for two of three samples or incomplete metal coating coverage (as depicted in FIG. 6) for only one of the three samples (about 20% to 30% based on visual inspection). FIG. 7 depicts an optical image 700 (converted from a color image to a grayscale image) of a second example of an electroplated plaque made via a method that utilized formulation “FIB” (see Table 1) that also did not include polar polymers and that also resulted in incomplete metal coating coverage (about 50% to 60% based on visual inspection). FIG. 8A depicts an optical image 800 (converted from a color image to a grayscale image) of an electroplated plaque made via a method that utilized formulation “F3” (see Table 1) that also did not include polar polymers and that also resulted in incomplete metal coating coverage (about 90% to 95% based on visual inspection). FIG. 9A depicts an optical image 900 (converted from a color image to a grayscale image) of an electroplated plaque made via a method that utilized one example of a metallizable thermoplastic composition (i.e., formulation “F6” in Table 1) of the present disclosure that resulted in complete metal coating coverage (100% based on visual inspection). Thus, the aforementioned figures illustrate that the plated metal surface coverage increases by increasing POE content from 5 wt. % (i.e, for “Fl A” as shown in FIG. 6) to 10 wt. % (i.e., for “FIB” as shown in FIG. 7) to 25 wt. % (i.e., for “F3” as shown in FIG. 8A). However, the optical image 900 of FIG. 9A illustrates that complete metal surface coverage (i.e., 100%) was achieved by incorporating 5 wt. % of the polar polymer PVOH (i.e., formulation “F6” in Table 1) along with an optimal loading of POE.

[0064] FIG. 8B and FIG. 9B show SEM images 810 and 910, respectively, of two etched plaques made from PP composition “F3” (see Table 1) and PP composition “F6” (see Table 1), respectively. The inventors have noted that the SEM images 810 and 910 clearly illustrate that an increased number of circular nano / micro pores are created in the case of the etched plaque made from PP composition “F6” (as shown in the SEM image 910 of FIG. 9B), which may be attributed to the presence of PVOH. Without wishing to be bound by theory, theinventors believe that the presence of PVOH helps to enhance the wettability of the PP composition plaque and hence increases the metal plating surface coverage with higher metal adhesion strength. The inventors note that, though these working examples are based on a particular ethylene-octene based POE (i.e., FORTIFY C5070 from SABIC), similar inventive compositions may be obtained with the use of various other C4-C10 alpha-olefins.Table 1FORTIFY C5070 is an examples of an ethylene based alpha-olefin elastomer (e.g., an ethylene-octene based elastomer) that is commercially available from SABIC.2Tafmer DF 605 is an example of an ethylene based alpha-olefin elastomer (e.g., an ethylene-butene based elastomer) that is commercially available from Mistui Chemicals, Inc.3Short glass fibers (“SGF”), having diameter ~13pm / length ~3-4mm, are an example of an inorganic filler (e.g., a reinforcing additive).4Poly(vinyl alcohol) (“PVOH”) is one example of a polar polymer, which may correspond to a Poval grade (commercially available from Kurarary, Inc.).Table 2

[0065] FIG. 10 is a flowchart depicting an example of a method 1000 that includes etching a surface of a thermoplastic (where the thermoplastic comprises a metallizable thermoplastic composition according to the present disclosure) and bonding a metal layer to the thermoplastic after etching the surface of the thermoplastic (e.g., to form a metallized thermoplastic article), according to one embodiment.

[0066] In the example depicted in FIG. 10, the method 1000 includes etching a surface of a thermoplastic, at block 1010. The thermoplastic may correspond to any of the metallizable thermoplastic compositions of the present invention. Specifically, the thermoplastic corresponds to metallizable thermoplastic composition that includes (at least): polypropylene; an ethylene based alpha-olefin elastomer; an inorganic filler; and one or more polar polymers.

[0067] While not shown in the example depicted in FIG. 10, etching the surface of the thermoplastic, at block 1010, may comprise etching the surface of the thermoplastic with an oxidizing agent, such as hexa-chrome sulfuric acid, tri-chrome, potassium permanganate, manganese-based etching solutions, or any combination thereof.

[0068] The method 1000 also includes bonding a metal layer to the thermoplastic after etching the surface of the thermoplastic, at block 1020. In some aspects, the bonding is between the metal layer and the etched surface. In some aspects, metallization of the thermoplastic may be carried out by electroless plating or a combination of electroless plating and electroplating. In some aspects, the bond between the metal layer and the thermoplastic may have a peel strength of 0.3 N / mm to 3 N / mm, associated with uniform surface coverage (or substantially uniform surface coverage) (see e.g., Table 2 above). In some aspects, the metal layer bonded to the thermoplastic may comprise nickel, copper, chromium, silver, gold, zinc, or metal alloys.

[0069] While not shown in the example depicted in FIG. 10, the method 1000 may result in the formation of a metallized thermoplastic article. According to some aspects, the metallized thermoplastic article may be configured to be comprised in one or more of the following: a component used in an electrical or electronic device, a component of a telecommunication device, RF filter, EMI shielding, wave-guide, antenna substrate, frequency selective surface, components of appliances, furniture, packaging, automotive interior components, automotive exterior components, badges, trims, electrical vehicle battery cover, and thermal management component.

[0070] In the context of the present disclosure, at least the following 15 aspects are described. Aspect 1 is metallizable thermoplastic composition. The metallizable thermoplastic composition comprises polypropylene, an ethylene based alpha-olefin elastomer, an inorganic filler, and one or more polar polymers. Aspect 2 is the metallizable thermoplastic composition of aspect 1, wherein the ethylene based alpha-olefin elastomer comprises a C4-C10 alpha-olefin. Aspect 3 is the metallizable thermoplastic composition of any of aspect 2, wherein the ethylene based alpha-olefin elastomer includes an ethyl ene-butene based elastomer. Aspect 4 is the metallizable thermoplastic composition of any of aspect 2, wherein the ethylene based alphaolefin elastomer includes an ethylene-octene based elastomer. Aspect 5 is the metallizable thermoplastic composition of any of aspects 1 to 4, wherein the metallizable thermoplastic composition comprises 10 wt. % to 30 wt. % of the ethylene based alpha-olefin elastomer Aspect 6 is the metallizable thermoplastic composition of any of aspects 1 to 5, wherein the metallizable thermoplastic composition comprises 2 wt. % to 25 wt. % of the one or more polarpolymers. Aspect 7 is the metallizable thermoplastic composition of any of aspects 1 to 6, wherein the metallizable thermoplastic composition comprises 10 wt. % to 40 wt.% of the inorganic filler. Aspect 8 is the metallizable thermoplastic composition of any of aspects 1 to 7, wherein the metallizable thermoplastic composition comprises 40 wt. % to 76 wt. % polypropylene. Aspect 9 is metallizable thermoplastic composition of any of aspects 1 to 8, wherein: the one or more polar polymers include one or more of the following polar polymers: poly(vinyl alcohol), ethylene vinyl alcohol, polyvinylpyrrolidone, polypropylene acrylic acid, polyethylene acrylic acid, polypropylene acrylate, polyethylene acrylate, polypropylene methacrylate, polyethylene methacrylate, polyacrylic acid, polymethacrylic acid, polyacrylate, polymethacrylate, and ionomers; and a percentage of polar groups in the one or more polar polymers is in a range of 5% to 100%. Aspect 10 is the metallizable thermoplastic composition of any of aspects 1 to 9, wherein the inorganic filler comprises one or more of the following: aluminum oxide, zinc oxide, titanium dioxide, zirconium oxide, calcium carbonate, talc, silica, glass beads, hollow glass beads, glass fibers, aluminum oxide fibers, carbon fibers, and graphene.

[0071] Aspect 11 is a method comprising: etching a surface of a thermoplastic, the thermoplastic comprising the metallizable thermoplastic composition of any of aspects 1 to 10; and after etching the surface of the thermoplastic, bonding a metal layer to the thermoplastic. Aspect 12 is the method of aspect 11, wherein: etching the surface of the thermoplastic comprises etching the surface of the thermoplastic with an oxidizing agent, wherein the oxidizing agent comprises hexa-chrome sulfuric acid, tri-chrome sulfuric acid, potassium permanganate, manganese-based etching solutions, or any combination thereof; the bonding is between the metal layer and the etched surface; metallization of the thermoplastic is carried out by electroless plating or a combination of electroless plating and electroplating; and the bond between the metal layer and the thermoplastic has a peel strength of 0.3 N / mm to 3 N / mm, with substantially uniform surface coverage. Aspect 13 is the method of any of aspects 11 or 12, wherein the metal layer comprises nickel, copper, chromium, silver, gold, zinc, or any combination thereof.

[0072] Aspect 14 is a metallized thermoplastic article. The metallized thermoplastic article comprises a metal layer bonded to a thermoplastic, the thermoplastic comprising themetallizable thermoplastic composition of any of aspects 1 to 10. Aspect 15 is the metallized thermoplastic article of aspect 14, wherein the metallized thermoplastic article is configured to be comprised in one or more of the following: a component used in an electrical or electronic device, a component of a telecommunication device, radio-frequency (RF) filter, EMI shielding, wave-guide, antenna substrate, frequency selective surface, components of appliances, furniture, packaging, automotive interior components, automotive exterior components, badges, trims, electrical vehicle battery cover, and thermal management component.

[0073] Although embodiments of the present application and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the embodiments as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, compound of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the above disclosure, processes, machines, manufacture, compounds of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compounds of matter, means, methods, or steps.

Claims

CLAIMS1. A metallizable thermoplastic composition, comprising: polypropylene; an ethylene based alpha-olefin elastomer; an inorganic filler; and one or more polar polymers.

2. The metallizable thermoplastic composition of claim 1, wherein the ethylene based alpha- olefin elastomer comprises a C4-C10 alpha-olefin.

3. The metallizable thermoplastic composition of claim 2, wherein the ethylene based alpha- olefin elastomer includes an ethylene-butene based elastomer.

4. The metallizable thermoplastic composition of claim 2, wherein the ethylene based alpha- olefin elastomer includes an ethylene-octene based elastomer.

5. The metallizable thermoplastic composition of any of claims 1 to 4, wherein the metallizable thermoplastic composition comprises 10 wt. % to 30 wt. % of the ethylene based alpha-olefin elastomer.

6. The metallizable thermoplastic composition of any of claims 1 to 5, wherein the metallizable thermoplastic composition comprises 2 wt. % to 25 wt. % of the one or more polar polymers.

7. The metallizable thermoplastic composition of any of claims 1 to 6, wherein the metallizable thermoplastic composition comprises 10 wt. % to 40 wt.% of the inorganic filler.

8. The metallizable thermoplastic composition of any of claims 1 to 7, wherein the metallizable thermoplastic composition comprises 40 wt. % to 76 wt. % of polypropylene.

9. The metallizable thermoplastic composition of any of claims 1 to 8, wherein: the one or more polar polymers include one or more of the following polar polymers: poly(vinyl) alcohol, ethylene vinyl alcohol, polyvinylpyrrolidone, polypropylene acrylic acid, polyethylene acrylic acid, polypropylene acrylate, polyethylene acrylate, polypropylene methacrylate, polyethylene methacrylate, polyacrylic acid, polymethacrylic acid, polyacrylate, polymethacrylate, and ionomers; and a percentage of polar groups in the one or more polar polymers is in a range of 5% to 100%.

10. The metallizable thermoplastic composition of any of claims 1 to 9, wherein the inorganic filler comprises one or more of the following: aluminum oxide, zinc oxide, titanium dioxide, zirconium oxide, calcium carbonate, talc, silica, glass beads, hollow glass beads, glass fibers, aluminum oxide fibers, carbon fibers, and graphene.

11. A method comprising: etching a surface of a thermoplastic, the thermoplastic comprising the metallizable thermoplastic composition of any of claims 1 to 10; and after etching the surface of the thermoplastic, bonding a metal layer to the thermoplastic.

12. The method of claim 11, wherein: etching the surface of the thermoplastic comprises etching the surface of the thermoplastic with an oxidizing agent, wherein the oxidizing agent comprises hexa-chrome sulfuric acid, tri-chrome, potassium permanganate, manganese-based etching solutions, or any combination thereof; the bonding is between the metal layer and the etched surface;metallization of the thermoplastic is carried out by electroless plating or a combination of electroless plating and electroplating; and the bond between the metal layer and the thermoplastic has a peel strength of 0.3 N / mm to 3 N / mm, with substantially uniform surface coverage.

13. The method of any of claims 11 or 12, wherein the metal layer comprises nickel, copper, chromium, silver, gold, zinc, or any combination thereof.

14. A metallized thermoplastic article comprising: a metal layer bonded to a thermoplastic, the thermoplastic comprising the metallizable thermoplastic composition of any of claims 1 to 10.

15. The metallized thermoplastic article of claim 14, wherein the metallized thermoplastic article is configured to be comprised in one or more of the following: a component used in an electrical or electronic device, a component of a telecommunication device, radiofrequency (RF) filter, EMI shielding, wave-guide, antenna substrate, frequency selective surface, components of appliances, furniture, packaging, automotive interior components, automotive exterior components, badges, name plates, trims, electrical vehicle battery cover, and thermal management component.

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