Methods of preparing polypropylene compounds for metallization and metallization thereof

Abstract

Disclosed are methods of preparing a polypropylene compound substrate for metallization that includes treating a surface of the substrate with a pre-etching treatment fluid comprising toluene. The treated surface can thus be more amenable to etching as compared to conventional processes. Also disclosed are metallized articles comprising a polypropylene compound substrate 5 and a metal layer attached to the substrate, wherein the peel strength of the attachment of the metal layer to the substrate is ≥0.10 N / mm.

Description

METHODS OF PREPARING POLYPROPYLENE COMPOUNDS FOR METALLIZATION AND METALLIZATION THEREOFFIELD

[0001] The present disclosure generally relates to compounds that comprise primarily propylene (polypropylene compounds). More specially, the present disclosure relates to preparing polypropylene compounds for metallization and metallization of such prepared compounds.BACKGROUND

[0002] 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 equipment, computer body parts, office equipment, machinery, and packaging. Typically, metal deposition on plastic surfaces is accomplished by techniques such as electroless plating, electroplating, and the like. One key challenge in electroless plating of a 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.

[0003] The conventional procedure used to make changes to the polymer substrate involves etching the polymer surface with strong oxidizing solutions such as hexa-chrome 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 such as 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 acrylonitrile-butadiene-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 BD will get selectively etched with oxidizing agents leading to the formation of micro-cavities 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.BRIEF SUMMARY

[0004] There is a need to make polypropylene compounds amenable to metallization using standard electroless plating and electroplating processes. The present methods treat a polypropylene compound substrate with toluene to make the substrate more amenable to etching. Such pre-etching treatment targets certain components of the polypropylene compound substrate to create nano / micro-pores. After these nano / micro-pores are created by the pre-etching treatment, the polypropylene compound substrate is etched with typical etching materials. The sequential treating and etching of the surface of the polypropylene compound creates nano / micro pores that promote anchoring of the metal during the metallization process, thereby leading to an increase in the adhesion strength of the bond between the two surfaces, as compared with conventional processes.

[0005] Some configurations of the disclosure include a method comprising forming a polypropylene compound substrate and treating a surface of the substrate with a pre-etching treatment fluid comprising toluene for a period in a range of 5 to 300 seconds, wherein the preetching treatment fluid is at a temperature in a range of 25°C to 95°C during the period.

[0006] Some configurations of the disclosure include a metallized article comprising a polypropylene compound substrate and a metal layer attached to the substrate, wherein the peel strength of the attachment of the metal layer to the substrate is >0. lON / mm.

[0007] The following includes definitions of various terms and phrases used throughout this specification.

[0008] 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 embodiment the terms are defined to be within 10%, preferably, within 5%, more preferably, within 1%, and most preferably, within 0.5%.

[0009] 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).

[0010] 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.

[0011] The term “substantially” and its variations are defined to include ranges within 10%, within 5%, within 1%, or within 0.5%.

[0012] 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.

[0013] The term “effective,” as that term is used in the specification and / or claims, means adequate to accomplish a desired, expected, or intended result.

[0014] 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.”

[0015] 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.

[0016] The process of the present invention can “comprise,” “consist essentially of,” or “consist of’ particular ingredients, components, compositions, compounds, etc., disclosed throughout the specification.

[0017] 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.% andall values and ranges there between, or 50.1 vol. % to 100 vol. % and all values and ranges there between.

[0018] 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 invention 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 be combined 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

[0019] For a more complete understanding, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

[0020] FIG. 1 depicts a conceptual flowchart of an example of the present methods of preparing polypropylene compounds for metallization and metallization of such compounds.

[0021] FIG. 2 depicts a scanning electron microscope (SEM) image of a certain polypropylene compound subjected to hexa-chrome sulfuric acid (HCSA) treatment at 70°C for 20 minutes.

[0022] FIG. 3 depicts an SEM image of a certain polypropylene compound subjected to sequential pre-treatment with toluene at about 85°C for 30 seconds and then with HCSA at 70°C for 20 minutes.

[0023] FIG. 4 is a graph depicting peel strength of copper plated on ABS and polypropylene compounds with different pre-treatments.DETAILED DESCRIPTION

[0024] In implementations of this disclosure, a polypropylene compound based article is treated with toluene prior to etching with, for example, any of hexa-chrome sulfuric acid (HCSA), tri-chrome, potassium permanganate, and manganese-based etching solutions, or a combination thereof. In some configurations, the polypropylene compound incorporates polycarbonate and / or styrene-acrylonitrile grafted butadiene into a polypropylene compound to help increase the surface polarity of the polypropylene compound and thereby make the surface of the polypropylene compound more amenable to the etching process.

[0025] In aspects of the disclosure, the polypropylene composition comprises 55 wt. % to95 wt. % or any range therein, including ranges of 55 wt. % to 60 wt. %, 60 wt. % to 65 wt. %, 65 wt. % to 70 wt. %, 70 wt. % to 75 wt. %, 75 wt. % to 80 wt. %, 80 wt. % to 85 wt. %, 85 wt. % to90 wt. %, 90 wt. % to 95 wt. of polypropylene.

[0026] In some implementations of the disclosure, polypropylene is melt blended with a reinforcing filler and an additive in an extruder set-up. In some configurations, the reinforcing filler comprises one or more of the following: an inorganic material, talc, silica, glass beads, hollow glass beads, glass fibers, and alumina fibers. In aspects of the disclosure, the polypropylene compound includes 5 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. %, and 35 wt. % to 40 wt. % of reinforcing filler.

[0027] In some implementations, the polypropylene compound comprises additives such as one or more of the following: polycarbonate, and / or styrene-acrylonitrile grafted butadiene. The quantities of these additives in the polypropylene compound can be optimized in order to produce a polypropylene compound that enables high metal adhesion and exhibit mechanical, thermal and electrical properties appropriate for the target application. In some aspects, the polypropylene compound includes 2 wt. % to 20 wt. % or any range therein, including 2 wt. % to 4 wt. %, 4 wt. % to 6 wt. %, 6 wt. % to 8 wt. %, 8 wt. % to 10 wt. %, 10 wt. % to 12 wt. %, 12 wt. % to 14 wt. %, 14 wt. % to 16 wt. %, 16 wt. % to 18 wt. % and 18 wt. % to 20 wt. % of polycarbonate. And in some aspects, the polypropylene compound includes 2 wt. % to 20 wt. % or any range therein, including 2 wt. % to 4 wt. %, 4 wt. % to 6 wt. %, 6 wt. % to 8 wt. %, 8 wt. % to 10 wt. %, 10 wt.% to 12 wt. %, 12 wt. % to 14 wt. %, 14 wt. % to 16 wt. %, 16 wt. % to 18 wt. % and 18 wt. % to 20 wt. % of styrene-acrylonitrile grafted butadiene. Although this disclosure is not bound by the following theory, it is believed that incorporation of polycarbonate and / or styrene-acrylonitrile grafted butadiene into polypropylene helps to increase the surface polarity because of preferential migration of these additives to the surface. In some implementations, the polypropylene compound further comprises one or more of: a stabilizer, a coupling agent, and a dispersing aid.

[0028] The polypropylene compounds of the present disclosure can be made by various methods known in the art. For example, components, such as polypropylene, reinforcing filler(s), and additive(s), can be mixed together and then melt-blended to form the polypropylene compound. 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.

[0029] In some aspects, the 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 it directly into the extruder at the throat and / or downstream through a side stuffer, 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, disc-pack 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. 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, shaping, or forming.

[0030] Mixtures including any combination of the foregoing mentioned components can be subjected to multiple blending and forming steps if desirable. For example, the plastic 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 plastic 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 or biaxial orientation.

[0031] Shaped, formed, casted, or molded articles comprising the plastic polypropylene compounds are also provided. The plastic polypropylene compounds can be molded into useful shaped articles by a variety of methods, such as injection 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 plastic polypropylene compound coated with a metal layer).

[0032] Referring to FIG. 1, aspects of the disclosure include a method 10 of metallizing a polypropylene compound. As shown in FIG. 1, method 10 includes, at block 100, melt-blending a plurality of components comprising polypropylene, a reinforcing filler, and an additive to form the substrate. The melt-blending can be carried out in an extruder or in a melt blender. In some configurations, the additive can comprise one or more of the following components: polycarbonate and styrene-butadiene- styrene. And in some configurations, the reinforcing filler can comprise one or more of the following: glass beads, glass fibers, and other ceramic fibers.

[0033] In the depicted example, block 101 includes treating a surface of the substrate with a pre-etching fluid comprising toluene. In some configurations, the treating of the surface, at block 101, is carried out such that the temperature of the pre-etching fluid is at a temperature of 25°C to 95°C or any range therein, including 25°C to 30°C, 30°C to 35°C, 35 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, 80°C to 85°C, 85°C to 90°C, and 90°C to 95°C for a period in a range of 5 to 300 seconds or any range therein, including 5 to 30 seconds, 30 to 60 seconds, 60 to 90 seconds, 90 to 120 seconds,120 to 150 seconds, 150 to 180 seconds, 180 to 210 seconds, 210 to 240 seconds, 240 to 270 seconds, and 270 to 300 seconds. In aspects of the disclosure, the substrate can initially be at a lower temperature than the pre-etching fluid, e.g., at room temperature (20°C to 22°C); and once the substrate comes into contact with the pre-etching fluid, it is envisaged that the surface of the substrate can attain thermal equilibrium with pre-etching fluid, depending on how long the preetching fluid is in contact with the substrate.

[0034] As depicted in the example, method 10 includes, at block 102, etching the surface of the substrate with any of hexa-chrome sulfuric acid (HCSA), tri-chrome, potassium permanganate, and manganese-based etching solutions, or a combination thereof. In some configurations, the etching of the surface, at block 102, is carried out such that the temperature of the etching solution is 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, and 75°C to 80°C, for a period in a range of 5 to 60 minutes and any range therein, including 5 to 10 minutes, 10 to 15 minutes, 15 to 20 minutes, 20 to 25 minutes, 25 to 30 minutes, 30 to 35 minutes, 35 to 40 minutes, 40 to 45 minutes, 45 to 50 minutes, 50 to 55 minutes, and 55 to 60 minutes. In aspects of the disclosure, the substrate can initially be at a lower temperature than the etching solution, e.g., at room temperature (20°C to 22°C); and once the substrate comes into contact with the etching solution, it is envisaged that the surface of the substrate can attain thermal equilibrium with etching solution, depending on how long the etching solution is in contact with the substrate.

[0035] In the depicted example, method 10, at block 103, can comprise depositing colloidal palladium into micro-pores on the surface of the substrate via a chemical redox reaction. In some configurations, the depositing of the colloidal palladium, at block 103, is carried out at a temperature of 25°C to 50°C for 1 to 10 minutes. In the depicted example, in method 10 after each of block 101, block 102, and block 103, the substrate can be rinsed with water before proceeding to the next step.

[0036] In the depicted example, block 104 involves attaching a metal layer to the etched surface of the substrate. In some configurations, the attaching of the metal layer includes an electroless process. And in some configurations, the attaching of the metal layer includes anelectroplating process. The metal that is attached to the substrate can be any one of nickel, copper, aluminum, gold, platinum, and an alloy thereof.

[0037] One suitable measure of the success of bonding between the metal layer and the polymer substrate is by measuring the peel strength, where the greater the peel strength the better is the adherence of the metal on the polymer substrate. In some configurations, the peel strength of the attached metal layer to the etched surface of the substrate is >0.10 N / mm, or any range therein, including 0.10 to 1.5 N / mm, 0.10 to 0.20 N / mm, 0.20 to 0.30 N / mm, 0.30 to 0.40 N / mm, 0.40 to 0.50 N / mm, 0.50 to 0.60 N / mm, 0.60 to 0.70 N / mm, 0.70 to 0.80 N / mm, 0.80 to 0.90 N / mm, 0.90 to 1.0 N / mm, 1.0 to 1.10 N / mm, 1.10 to 1.20 N / mm, 1.20 to 1.30 N / mm, 1.30 to 1.40 N / mm, and 1.40 to 1.50 N / mm.

[0038] The metallized polypropylene compounds disclosed herein can be used to make a plurality of different components such as 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 shield, wave-guide, antenna substrate, automotive interior component, automotive exterior component, and packaging.

[0039] Although aspects of the present disclosure have been described with reference to blocks of FIG. 1, it should be appreciated that operation of the present disclosure is not limited to the particular blocks and / or the particular order of the blocks illustrated in FIG. 1. Accordingly, aspects of the disclosure may provide functionality as described herein using various blocks in a sequence different than that of FIG. 1.

[0040] As part of the present disclosure, specific examples are included below. The examples are for illustrative purposes only and are not intended to limit the disclosure. Those of ordinary skill in the art will readily recognize parameters that can be changed or modified to yield essentially the same results.EXAMPLES

[0041] A first polypropylene (PP) compound was prepared to include 58 wt. % polypropylene, 20 wt. % of low dielectric constant (Dk) glass fiber (LowDkGF: Grade-ECS305- 3-K-HL, procured from CPIC / Chongqing Polycomp International Corp., China), 10 wt. %polycarbonate (PC), 10 wt. % glass bubble (GB), and 2 wt. % of processing additives including 0.1 wt. % anti-oxidant (Irganox 1010), 0.1 wt. % of heat stabilizer (Irgaphos-168), 1.6 wt. % of coupling agent (maleic anhydride grafted polypropylene), and 0.2 wt. % of nucleating agent (talc). The first polypropylene compound substrate was treated with hexa-chrome sulfuric acid (HCSA) at 70°C for 20 minutes. FIG. 2 depicts a scanning electron microscope (SEM) image of the first polypropylene compound substrate, which was subjected to HCSA treatment at 70°C for 20 minutes.

[0042] A second polypropylene compound was prepared to include 58 wt. % polypropylene, 20 wt. % LowDkGF, 10 wt. % polycarbonate, 10 wt. % glass bubble, and 2 wt. % of processing additives including 0.1 wt. % anti-oxidant (Irganox 1010), 0.1 wt. % of heat stabilizer (Irgaphos-168), 1.6 wt. % of coupling agent (maleic anhydride grafted polypropylene) and 0.2 wt. % of nucleating agent (talc). The second polypropylene compound substrate was then sequentially treated with hot toluene at 85°C (where the substrate was initially at room temperature) for 30 seconds and then in HCSA at 70°C for 20 minutes. FIG. 3 depicts an SEM image of the second polypropylene compound substrate, which was subjected to with hot toluene at 85°C for 30 seconds and then HCSA treatment at 70°C for 20 minutes.

[0043] From FIG. 2 and FIG. 3, it can be seen that treatment of the polypropylene compound substrate with hot toluene, followed by the treatment with HCSA helps to form interlocking nano / micro-pores, which can lead to a relatively better metal adhesion, which is evidenced by higher peel strength values, as shown in FIG. 4.

[0044] FIG. 4 shows that metal peel strength of as high as 0.27±0.05 N / mm was obtained for the second polypropylene compound sample upon sequential exposure to hot toluene and HCSA. It is interesting to note that although the peel strength values obtained for polypropylene compound substrates which are pretreated either with HCSA or with hot toluene are about 0.08 N / mm, a significantly higher peel strength value (about 0.27 N / mm) is evident for polypropylene compound substrate which is sequentially pretreated with hot toluene and HCSA, indicating a non- obvious synergistic influence of combining two pretreatments (hot toluene and HCSA) to result in the desired improvement in metal adhesion.

[0045] Moreover, the achieved peel strength of the attachment between polypropylene compounds and metal as a result of using sequential exposure to hot toluene and HCSA was found to be similar to the peel strength value obtained for ABS using a standard HCSA pre-treatment as shown in FIG. 4. The obtained results appear to suggest that using pre-treatment of hot toluene helps to swell the polypropylene compound surface, leading to the formation of nano / micro-pores upon exposure to HCSA. It also confirms mechanical interlocking of plated copper within the formed nano / micro-pores, which leads to a high metal adhesion strength.

[0046] The significant increase of peel strength value, shown in FIG. 4, would not be expected when neat polypropylene (without any additive such as polycarbonate, and reinforcing fillers such as glass fiber and glass bubbles or a combination of them) is sequentially pretreated with hot toluene and HCSA as depicted in Table 1, which details the qualitative evaluation of peel strength of ABS and different polypropylene compounds subjected to different pre-treatment, by cross-hatch method, indicating the key role of the additives to result in the desired improved metal adhesion. Table 2 below further details the adhesion class of various polypropylene compounds subj ected to different pre-treatments.TABLE 1TABLE 2

[0047] In the context of the present disclosure, at least the following 15 aspects are described. Aspect l is a method for forming a polypropylene compound substrate, and treating a surface of the substrate with a pre-etching treatment fluid comprising toluene for a period in a range of 5 to 300 seconds, wherein the pre-etching treatment fluid is at a temperature in a range of 25°C to 95°C during the period. Aspect 2 is the method of aspect 1, wherein the forming of the polypropylene compound substrate comprises melt-blending a plurality of components comprising polypropylene, a reinforcing filler, and an additive. Aspect 3 is the method of aspect 2, wherein the melt-blending is carried out in an extruder and / or in a melt blender. Aspect 4 is the method of any of aspects 1 to 3, further comprising etching the surface with any of hexa-chrome sulfuric acid (HCSA), tri-chrome, potassium permanganate, and manganese-based etching solutions, or a combination thereof. Aspect 5 is the method of aspect 4, further comprising depositing colloidal palladium into micro-pores on the surface via a chemical redox reaction. Aspect 6 is the method of aspect 5, further comprising attaching a metal layer to the etched surface of the substrate. Aspect 7 is the method of aspect 6, wherein the peel strength of the attachment between the metal layer and the etched surface of the substrate is >0.10 N / mm.

[0048] Aspect 8 is a metallized article comprising a polypropylene compound substrate, and a metal layer attached to the substrate, wherein the peel strength of the attachment of the metal layer to the substrate is >0.10 N / mm. Aspect 9 is the metallized article of aspect 8, wherein the substrate comprises polypropylene; reinforcing filler, and an additive. Aspect 10 is the metallizedarticle of aspect 9, wherein the reinforcing filler comprises one or more of the following: an inorganic material, talc, silica, glass beads, hollow glass beads, glass fibers, and alumina fibers. Aspect 11 is the metallized article of any of aspects 9 and 10, wherein the additive comprises one or more of the following: polycarbonate and styrene-acrylonitrile grafted butadiene. Aspect 12 is the metallized article of any of aspects 9 to 11, wherein the substrate comprises 5 to 40 wt. % reinforcing filler. Aspect 13 is the metallized article of any of aspects 9 to 12, wherein the substrate comprises 2 to 20 wt. % additive. Aspect 14 is the metallized article of any of aspects 9 to 13, wherein the substrate further comprises one or more of: a stabilizer, a coupling agent, and a dispersing aid. Aspect 15 is the metallized article of any of aspects 8 to 14, wherein the metallized 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 shield, wave-guide, antenna substrate, automotive interior component, automotive exterior component, and packaging.

[0049] 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, composition 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, compositions 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, compositions of matter, means, methods, or steps.

Claims

CLAIMSWhat is claimed is:

1. A method comprising: forming a polypropylene compound substrate; and treating a surface of the substrate with a pre-etching treatment fluid comprising toluene for a period in a range of 5 to 300 seconds, wherein the pre-etching treatment fluid is at a temperature in a range of 30°C to 95°C during the period.

2. The method of claim 1, wherein the forming of the polypropylene compound substrate comprises: melt-blending a plurality of components comprising polypropylene, a reinforcing filler, and an additive.

3. The method of claim 2, wherein the melt-blending is carried out in an extruder and / or in a melt blender.

4. The method of any of claims 1 to 3, further comprising: etching the surface with any of hexa-chrome sulfuric acid (HCSA), tri-chrome, potassium permanganate, and manganese-based etching solutions, or a combination thereof.

5. The method of claim 4, further comprising: depositing colloidal palladium into micro-pores on the surface via a chemical redox reaction.

6. The method of claim 5, further comprising: attaching a metal layer to the etched surface of the substrate.

7. The method of claim 6, wherein the peel strength of the attachment between the metal layer and the etched surface of the substrate is >0.10 N / mm.

8. A metallized article comprising: a polypropylene compound substrate; and a metal layer attached to the substrate, wherein the peel strength of the attachment of the metal layer to the substrate is >0.10 N / mm.

9. The metallized article of claim 8, wherein the substrate comprises polypropylene; reinforcing filler, and an additive.

10. The metallized article of claim 9, wherein the reinforcing filler comprises one or more of the following: an inorganic material, talc, silica, glass beads, hollow glass beads, glass fibers, and alumina fibers.

11. The metallized article of any of claims 9 and 10, wherein the additive comprises one or more of the following: polycarbonate and styrene-acrylonitrile grafted butadiene.

12. The metallized article of any of claims 9 to 11, wherein the substrate comprises 5 to 40 wt. % reinforcing filler.

13. The metallized article of any of claims 9 to 12, wherein the substrate comprises 2 to 20 wt. % additive.

14. The metallized article of any of claims 9 to 13, wherein the substrate further comprises one or more of: a stabilizer, a coupling agent, and a dispersing aid.

15. The metallized article of any of claims 8 to 14, wherein the metallized 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 shield, wave-guide, antenna substrate, automotive interior component, automotive exterior component, and packaging.

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