Method for directly bonding a metal to a polymer / polymer composite using a functionally active insertion layer

Abstract

A method of joining a metal part and a polymer / polymer composite part, comprising providing a metal part, providing a polymer or polymer composite part, inserting an insertion layer between the metal part and the polymer or polymer composite part, and heating the metal part to a temperature higher than the melting temperature of the polymer or polymer composite part and the insertion layer and lower than the degradation temperature, and simultaneously applying pressure to the combination of the metal part, the polymer or polymer composite part, and the insertion layer to combine the metal part and the polymer or polymer composite part into a joined assembly having a chemical bond therebetween.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims priority to U.S. Patent Application No. 18 / 223,829, filed on July 19, 2023, which claims the benefit of U.S. Provisional Application No. 63 / 391,030, filed on July 21, 2022. The entire disclosure of those applications is incorporated herein by reference.

[0002] This disclosure relates to joining materials, and more particularly, to methods for directly joining metals to polymers and / or polymer composites using a functionally active insertion layer.

Summary of the Invention

[0003] This section provides a general overview of the disclosure and does not disclose the full scope of the disclosure or all of its features.

[0004] According to the principles of the present teachings, a method for directly joining a polymer or polymer composite to a metal using a functionally active polymer insertion layer is provided under various mechanisms that apply heat and pressure to the metal side without any type of surface or material pretreatment or chemical treatment on either the metal side or the polymer / polymer composite side. Generally, polyolefin polymers are difficult to bond to any known metal, mainly due to their non - polar characteristics. Specifically, it is successfully demonstrated by the above - mentioned method that polyolefin - polymers or polyolefin - polymer - composites can be joined to base metals and electro - coated metals with a significant bonding strength using a functionally active insertion layer.

[0005] Further application areas will become apparent from the description provided herein. The description and examples in this summary are intended for illustrative purposes only and are not intended to limit the scope of the disclosure.

[0006] The drawings described in this specification are for the purpose of illustrating only selected embodiments and not all possible embodiments, and are not intended to limit the scope of the present disclosure.

Brief Description of the Drawings

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Best Mode for Carrying Out the Invention

[0022] Corresponding reference numerals refer to corresponding parts throughout several views of these drawings.

[0023] Next, exemplary embodiments will be described in more detail with reference to the accompanying drawings.

[0024] The exemplary embodiments are provided so that this disclosure will be thorough, and will fully convey the scope of this disclosure to those skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, etc. to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details are not required and that the exemplary embodiments may be embodied in many different forms and that none of them should be construed as limiting the scope of the present disclosure. In some exemplary embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

[0025] The terms used herein are for the purpose of describing particular exemplary embodiments only and are not intended to be limiting. As used herein, the singular forms "a", "an", and "the" may be intended to include the plural as well, unless the context clearly indicates otherwise. The terms "comprises", "comprising", "including", and "having" are inclusive and thus specify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. The steps, processes, and operations of the methods described herein should not be construed as necessarily requiring them to be performed in the particular order discussed or shown, unless specifically specified as the order of performance. It should also be understood that additional or alternative steps may be used.

[0026] When an element or layer is referred to as being "in contact with", "engaged with", "connected to", or "coupled to" another element or layer, the element or layer may be in direct contact with, engaged with, connected to, or coupled to the other element or layer, or there may be intervening elements or layers. In contrast, when an element is referred to as being "directly in contact with", "directly engaged with", "directly connected to", or "directly coupled to" another element or layer, intervening elements or layers may be absent. Other words used to describe the relationship between elements should be interpreted similarly (e.g., "directly between" for "between", "directly adjacent" for "adjacent", etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0027] For purposes of describing various elements, components, regions, layers, and / or portions, terms such as first, second, third, etc. may be used herein, but these elements, components, regions, layers, and / or portions should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or portion from another region, layer, or portion. The terms "first", "second", etc., and other numerical terms, as used herein, do not mean an order or sequence unless clearly indicated by the context. Thus, a first element, component, region, layer, or portion discussed below may be referred to as a second element, component, region, layer, or portion without departing from the teachings of the exemplary embodiments.

[0028] Spatially relative terms such as "inner", "outer", "directly below", "below", "beneath", "above", "over" may be used herein to facilitate description of the relationship of one element or feature to another element(s) or feature(s) as shown in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, an element described as "below" or "directly below" another element or feature would, when the device in the figures is turned over, be oriented "above" the other element or feature. Thus, the exemplary term "below" can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein are to be interpreted accordingly.

[0029] In accordance with the principles of the present teachings, a method and a product made by the presented process are provided, the method and product having advantageous steps and configurations related to the joining of uncoated metals and / or coated metals to polymers and / or polymer composites using a functionally active thin film insertion layer. That is, in some embodiments schematically shown in FIG. 1, the present teachings provide a joining method 10 in which a metal part 12 is joined to a polymer and / or polymer composite part 14 via an insertion film 16 using applied heat 100 and pressure 102 such that a joint 18 formed between the metal part 12 and the polymer / polymer composite part 14 is produced using the insertion film 16.

[0030] In some embodiments, the metal component 12 can include coated metal and / or uncoated metal (see FIGS. 5-7). That is, in some embodiments, the metal component 12 can include surface treatment and / or surface modification, examples of which include, but are not limited to, any form such as physical, chemical, thermal, laser, optical, electrochemical, electromagnetic, and / or combinations thereof. It should be understood that the surface of the metal component 12 can be cleaned using any chemical solvent. For example, without changing the surface roughness of the joint surface of the metal component, at least the joint surface can be degreased using a non-corrosive chemical substance. In some embodiments, the non-corrosive chemical substance is ethanol, acetone, or any surface degreasing non-corrosive agent. However, it should also be understood that in some embodiments, surface cleaning of the metal component 12 may not be necessary or desirable. Also, the coating (see at least FIG. 7) can be understood to include, but is not limited to, any type of electrodeposition coating, electroplating coating, corrosion-resistant (or atmospheric protection) coating, or the like, including those that include compatible or non-compatible adhesive coatings. In some embodiments, the metal surface has a roughness of less than 0.76 micrometers (μm).

[0031] In some embodiments, the metal component 12 can include any type (see FIGS. 5-7), examples of which include, but are not limited to, pure metal, ferrous metal or non-ferrous metal, any type of metal alloy, treated (including, but not limited to, any type of physical, chemical or metallurgical treatment), or untreated. Further, in some embodiments, the metal component 12 can be provided in any shape, size or form for any type of application.

[0032] In some embodiments, the polymer and / or polymer composite part 14 can have any kind of resin (specifically, but not limited to, polyolefin thermoplastic resin), and can be derived from any class of polymers, such as natural and / or synthetic, etc. without being limited hereinafter. In embodiments having the polymer composite part 14, the fibers in the polymer composite can be in any form, examples of which include, but are not limited to, any kind and / or form, glass fiber, carbon fiber, aramid fiber, short fiber, long fiber, continuous fiber, spherical fiber, and any other fiber, or a combination thereof. In some embodiments, the polymer and / or polymer composite part 14 can be in any form, examples of which include sheet, block, tube, pipe, or any other shape of any size or thickness. In some embodiments, the polymer and / or polymer composite part 14 can be in the form of an elastomer (natural rubber or synthetic rubber, or a preform / postform of a rubber material), examples of which include, but are not limited to, latex, natural rubber, ethylene propylene diene monomer (EPDM), or a combination / blend of two or more polymers, or any such form. In some embodiments, the polymer and / or polymer composite part 14 can include a polyolefin polymer, examples of which include those produced from very simple olefin monomers having no functional groups in their chemical structure.In some embodiments, the polymer and / or polymer composite part 14 can include a thermoplastic polyolefin, examples of which include, but are not limited to, polypropylene [Polypropyelene: PP (including homopolymers and / or copolymers)], low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), very-low-density polyethylene (VLDPE), ultra-low-density polyethylene (ULDPE), medium-density polyethylene (MDPE), polymethylpentene (PMP), polybutene-1 (PB-1), ethylene-octene copolymer, stereo-block PP, olefin block copolymer, propylene-butane copolymer, polyolefin elastomer, polyisobutylene (PIB), poly(alpha-olefin), ethylene propylene rubber (EPR), and ethylene propylene diene monomer (M-class) rubber (ethylene propylene diene monomer rubber: EPDM rubber), and combinations thereof.

[0033] In some embodiments, the insertion film layer 16 can include a thin film or thin layer that can be any kind of functional polymer or polar polymer (i.e., functionally active), examples of which include, but are not limited to, nylon (or polyamide PA, PA6, PA66, PA12, etc.), polyester (PET), polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), polycarbonate (PC), polyimide (PI), polyaryletherketone (PAEK), polyether ether ketone (PEEK), syndiotactic polystyrene (SPS), polyphthalamide (PPA), polybutylene terephthalate (PBT), polyoxymethylene (POM), polyamide-imide (PAI), poly methyl methacrylate (PMMA), polyphenylsulfone (PPSU, PPSF), vitrimer (covalent adaptable network (CAN)), etc., or combinations thereof. In some embodiments, the insertion film layer 16 can be a functionally active insertion layer different from the material of the polymer or polymer composite part 14. In some embodiments, the insertion film layer 16 can have a thickness of several nanometers, several microns, or several millimeters. In some embodiments, the insertion film layer 16 can be in any form, examples of which include, but are not limited to, thin films (solid or flexible) of any thickness in millimeters or microns, powder form, spray form (aerosol form), nanorods, nanoparticles, nanofilm, etc., and combinations thereof.However, it should be recognized that the insert film layer 16 is not envisioned to be in any kind of adhesive form. In some embodiments, the insert film layer 16 can be in a fiber-filled prepreg form and / or, in that form, the base polymer material is a thermoplastic polymer and the fibers can be in any form (continuous, small, long, chopped, spherical, etc.) or type (glass, carbon, aramid, natural, etc.) in the prepreg. In some embodiments, the insert film layer 16 can be made of a fiber-filled or fiber-unfilled vitrimer reinforcing material. In some embodiments, the reinforcing material is selected from the group consisting of natural fibers, glass fibers, carbon fibers, glass particles or silica particles. In some embodiments, the insert layer material can be mixed with a base polymer / polymer composite material either in-situ or ex-situ to form a mixture.

[0034] According to the present teachings, a method is provided in which an insertion film layer 16 made of a polymer and / or a polymer composite is inserted between a metal part 12 and a polymer part 14. The method further includes heating the metal part 12 using a heat source or heating system 102 and simultaneously activating a forging force system 106 to bring the assembly (i.e., the metal part 12, the polymer part 14, and the insertion film layer 16) into contact and maintain it under sufficient pressure to maintain intimate contact between the metal part 12, the polymer / polymer composite part 14, and the insertion film layer 16. That is, in some embodiments, the metal part 12, the polymer part 14, and the insertion film layer 16 are held under the pressure and heated on the metal side (i.e., the metal part 12) to a temperature high enough to reach the melting points of both the polymer part 14 and the insertion film layer 16, but not so high as to reach the polymer ignition point and the metal melting temperature. The respective molten polymers of the polymer part 14 and the insertion film layer 16 mix together by physical mixing (see FIGS. 12 and 14) and / or chemical reaction between effective polymer molecules. In the case of a polymer composite, the respective molten polymers form a polymer composite that is intermixed at the interface 18 (see FIGS. 12 and 14). Overall, a polymer melt pool of sufficient volume is created that chemically / atomically reacts and bonds intimately to the metal surface of the metal part 12 (see FIGS. 12 - 15).

[0035] In some embodiments, the heat source or heating system 102 can include any heat source, examples of which include external, internal, direct, indirect, derived, or any combination thereof. That is, the heat source 102 can be applied physically in contact with, or remotely from, the outside of the metal part 12, or from the inside of the metal part 12 using a molten pool of polymer or by any other combination. The heat source or heating system 102 can include laser heating, friction heating (e.g., but not limited to, friction spot (see FIGS. 5-7), friction lap, friction stir), melting (e.g., but not limited to, 3D printer) (see FIG. 11), hot water treatment heating, ultrasonic heating, injection mold heating (see FIGS. 9-10), induction heating, thermal heating, electrical resistance heating, laser heating, high energy beam heating, high speed plastic deformation heating, extrusion heating (see FIG. 8), extrusion molding, plastic molding, etc., and combinations thereof.

[0036] In some embodiments, the forging force system 106 can provide sufficient pressure to maintain intimate contact between the metal part 12, the polymer part 14, and the insert film layer 16. The forging force system 106 can include any type of system, examples of which include, but are not limited to, hydraulic, mechanical, electromechanical, servo-electronic actuators, etc., and combinations thereof. In some embodiments, the heat source 102 and the forging force system 106 can be an integrated system. In some embodiments, the compressive force applied by the forging force system 106 can be applied perpendicular to the bonding interface. A back support can be provided to counteract this compressive force.

[0037] Therefore, the method of the present disclosure is understood to provide a direct joining of a metal and a poorly weldable polymer / polymer composite material to manufacture and / or provide a cost-effective metal-polymer hybrid structure for structural lightweighting applications. Since no surface treatment of any kind is required on the metal side or the composite side, significant cost savings are achieved. Since the processing is simplified, the method also provides the ability to mass-produce.

[0038] Furthermore, the present disclosure enables joining by chemical bonding to a metal rather than mechanical interlocking (adhesion), providing the ability to join coated / uncoated metals to polyolefin thermoplastic polymer / polymer composites. In the present disclosure, no special surface / bulk treatment of any kind is required on the metal side or the polymer / polymer composite side, providing the ability to join coated (corrosion protection layers such as epoxy by electrodeposition coating, etc.) (see FIG. 15) metals, or uncoated metals to polymer / polymer composite materials.

[0039] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. The individual elements or features of a particular embodiment are generally not limited to that particular embodiment and, where applicable, are interchangeable and may be used in the selected embodiment even if not specifically shown or described. They may also be modified in many ways. Such modifications are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

Claims

1. A method for joining a metal part and a polymer / polymer composite part, comprising: providing a metal part; providing a polymer or polymer composite part; inserting an insertion layer between the metal part and the polymer or polymer composite part; and applying heat to the metal part to a temperature higher than the melting temperature and lower than the degradation temperature of the polymer or polymer composite part and the insertion layer, and simultaneously applying pressure to the combination of the metal part, the polymer or polymer composite part, and the insertion layer to combine the metal part and the polymer or polymer composite part into a joined assembly having a chemical bond therebetween. A method comprising the above.

2. The method according to claim 1, further comprising degreasing the bonding surface of the metal part using a non-corrosive chemical substance without changing the surface roughness of the bonding surface of the metal part.

3. The method according to claim 2, wherein the non-corrosive chemical substance is ethanol or acetone.

4. The method according to claim 2, wherein the non-corrosive chemical substance is a surface degreasing non-corrosive agent.

5. The method according to claim 2, wherein the metal part has a surface roughness of less than Ra 0.76 micrometers (μm).

6. The method according to claim 1, wherein the insertion layer is a functionally active polymer material layer.

7. The method according to claim 1, wherein the insertion layer is a composite material layer having a functionally active polymer as its base material matrix.

8. The method according to claim 1, wherein the insertion layer includes a reinforcing material.

9. The method according to claim 8, wherein the reinforcing material is selected from the group consisting of natural fibers or natural particles, glass fibers or glass particles, carbon fibers or carbon particles, glass particles or silica particles.

10. The method according to claim 1, wherein the insertion layer has a thickness in the range of 1 nanometer (nm) or more and 6 millimeters (mm) or less at the joint portion between the surface of the metal part and the surface of the polymer or polymer composite layer / part.

11. The method according to claim 1, wherein the step of providing a polymer or polymer composite part includes injection molding in which a molten polymer or polymer composite is placed on the metal part and the insertion layer is placed therebetween.

12. The method according to claim 1, wherein the step of providing the polymer or polymer composite part comprises an extrusion in which the molten polymer or polymer composite is placed on the metal part and the insertion layer is placed therebetween.

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