Nitrogen flush to improve heat resistance of heat-sensitive materials during injection molding of thermoplastic automotive parts

Abstract

A thermoplastic component formed by an outer surface layer and a core material for the purpose of using in vehicle exterior trim, exterior panel, or exterior body part with class A surface appearance. A process for injection molding of a reduced carbon footprint thermoplastic material comprising the steps of: a. Providing a first phase material which includes a thermoplastic resin; b. Adding a second phase organic waste filler material to said first phase thermoplastic resin, and, c. Injection molding an article from the combination in the presence of an inert gas for attenuation of any thermal degradation of the second organic waste filler during injection molding.

Description

[0001] NITROGEN FLUSH TO IMPROVE HEAT RESISTANCE OF HEAT-SENSITIVE MATERIALS DURING INJECTION MOLDING OF THERMOPLASTIC AUTOMOTIVE PARTS

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application is a PCT International Patent Application and claims the benefit of U.S. Provisional Patent Application No. 63 / 698,867, filed September 25, 2024, and U.S. Provisional Patent Application No. 63 / 588,427, filed October 6, 2023. The disclosures of the above applications are incorporated herein by reference.

[0004] FIELD OF THE INVENTION

[0005] The present invention relates to a nitrogen flush to improve heat resistance of heatsensitive materials during injection molding of thermoplastic automotive parts.

[0006] BACKGROUND OF THE INVENTION

[0007] ARBURG developed an air-tight hopper to inject nitrogen during molding of thermoplastic parts by increasing pressure inside the hopper up to 50 bar. This equipment is used to foam molded parts. This equipment is no longer offered commercially: https: / / www.plasticsmachinerymanufacturing.com / blow- molding / article / 13000673 / arburg-offers-3-processes-for-lightweight-molding.

[0008] Thermally-sensitive materials, like hemp, wood fiber and UBQ contain molecules of organic compounds, such as: cellulose and lignocellulose that typically burn and smoke below the processing temperature required for common resins used in automotive, like TPO, PP and PA.

[0009] Using lab-sized equipment, we found that thermal degradation is drastically reduced when the heat takes place under nitrogen atmosphere. Mucell is a foaming process that typically uses nitrogen to create micron-sized bubbles inside molded plastic parts. This kind of foaming is not in the scope of the invention as it is not intended to foam parts for lightweighting, but only introduce nitrogen into the melt to delay thermal degradation. Co-injection molding, also known as two-shot injection molding, is a manufacturing process utilized for producing plastic parts using multiple materials. This process involves injecting two or more different materials into a mold cavity either simultaneously or sequentially. Specifically, it uses a core material and a secondary material known as the skin. In our embodiment, the skin material consists of class A-capable TPO, while the core material is a carbon-negative material. Carbon-negative materials generally denote substances capable of sequestering carbon dioxide (CO2) from the atmosphere. In the automotive industry, the incorporation of carbon-negative materials offers the advantage of reducing the CO2 and CO2-equivalent footprint of plastic parts, thereby decreasing their overall global warming potential.

[0010] Naturally occurring carbon-negative materials include algae, plants, and trees, which store CO2 in their trunks, roots, and leaves during photosynthesis. Conversely, engineered carbon-negative materials are artificially derived from discarded materials and waste, which otherwise would be landfilled and generate new greenhouse gas emissions. Examples of engineered carbon-negative material are a) UBQ (“ubiquitous materials” available from UBQ Materials 16690 Collins Ave Suite 802, Sunny Isles, FL 33160), which in essence is a mixture of organic waste and unsortable, non-recyclable mixed plastics from municipal trash, b) paint regrind or paint sludge char from automotive paint lines.

[0011] The integration of carbon-negative materials in plastic automotive parts promotes circularity, which is desirable in automotive manufacturing today. Achieving circularity establishes a closed-loop system aimed at minimizing landfill waste and enhances the value of discarded materials that would otherwise necessitate landfilling, potentially leading to increased greenhouse gas emissions, particularly if the waste is organic-based. However, achieving circularity is not without challenges.

[0012] Carbon-negative materials pose challenges when used in automotive plastic parts, primarily due to 1 ) their limited effectiveness in providing mechanical reinforcement for structural components, 2) their incompatibility with achieving a class A surface finish for visible parts, and 3) thermal sensitivity to the processing temperatures required for thermoplastics such as TPO, PP, and PA6.

[0013] Relatively high processing temperatures can result in reduced mechanical performance due to excessive thermo-oxidative degradation of the carbon-negative filler, leading to poor surface characteristics, unpleasant odor, and smoke generation. Therefore, developing solutions to a) achieve minimum mechanical requirements, b) achieve a class A surface appearance, and c) widen the processing window, is crucial to enhancing the acceptance of carbon-negative materials in automotive part manufacturing.

[0014] Thermally sensitive materials, for example, discarded wood fiber, waste cardboard, natural fibers of cellulosic and lignocellulosic origin, and unsorted household waste, may be used in the automotive industry to the reduce the carbon footprint and increase the recovery of end-of-life automotive composite parts. However, the issue or thermal-sensitivity arises, as many of these materials tend to degrade during processing as their thermal degradation temperature is typically lower than the processing temperature required for molding.

[0015] SUMMARY OF THE INVENTION

[0016] In this disclosure, we describe our findings regarding the utilization of co-injection molding, nitrogen flushing, and a blend of antioxidants, co-stabilizers, and reactive additives to achieve the objectives mentioned above, thus facilitating the adoption of circular carbon-negative materials for automotive parts with class A.

[0017] Our invention extrapolates lab-sized results in which the use of nitrogen atmosphere drastically reduces and delays thermal degradation expressed as wt.%. For example, a sample of UBQ (i.e., unsorted household waste) exposed to 200°C under nitrogen atmosphere for 2 h loses < 6 wt.%, whereas the same material loses more than 38 wt.% in atmospheric air. Our invention relates to a simple method to inject nitrogen, argon and other inert gas into the throat of the injection molding press in order to mix the nitrogen into the melt during the molding process. The simplest method is to inject the nitrogen through the hopper.

[0018] Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

[0019] BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

[0021] Figure 1 is a perspective view of a typical injection molding set up using the process of the present invention;

[0022] Figure 2 is a detailed view showing injection of an inert gas into the hopper system in accordance with the present invention;

[0023] Figure 3 is a graph of test results showing the effectiveness of using the present invention to prevent thermal degradation of organic household waste type filler materials; Figure 4 is a graph showing the properties of a Class A surface prepared using thermoplastic olefins including the carbon negative UBQ fillers as set forth herein; and,

[0024] Figures 5a and 5B are view of the equipment set up for nitrogen padding of the pellet hopper in accordance with the present invention;

[0025] Figure 6 is a perspective view of the nitrogen supply; and

[0026] Figure 7 is a view of the nitrogen valving system for controlling flow.

[0027] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

[0029] Referring now to the drawings there is provided in accordance with the present invention:

[0030] A process for injection molding of a reduced carbon footprint thermoplastic material generally indicated at 10 comprising the steps of: a. Providing a first phase material which includes a thermoplastic resin; b. Adding a second phase 2 organic waste filler material to said first phase thermoplastic resin; and c. Injection molding an article from the combination in the presence of an inert gas for attenuation of any thermal degradation of the second organic waste filler during injection molding.

[0031] Referring to Figure 1 , a typical injection molding system generally indicated at 12 includes an injection molding machine 14 which is controlled by a controller 16. The machine includes a vacuum loader 18 which draws a vacuum on the material hopper 20. A nitrogen cylinder 22 and high-pressure hose 24 is used to inject an inert gas such as nitrogen, argon or the like which ensures that the organic household waste material is in a protective atmosphere during injection molding to prevent thermal oxygenation and / or other degradation of the material.

[0032] As an example, referring to Figure 3 the invention extrapolates lab-sized results in which the use of nitrogen atmosphere drastically reduces and delays thermal degradation expressed as wt.%. For example, a sample of UBQ (i.e., unsorted household waste) exposed to 200°C under nitrogen atmosphere for 2 h loses < 6 wt.%, whereas the same material loses more than 38 wt.% in atmospheric air. The invention provides a simple method to inject nitrogen, argon and other inert gas into the throat of the injection molding press in order to mix the nitrogen into the melt during the molding process. The simplest method is to inject the nitrogen through the hopper as is illustrated in Figure 2.

[0033] The phase 1 thermoplastic may be TPO, PP or PA, or other thermoplastic resin used as matrix in reinforced composites. It is within the scope of the present invention that fillers, additives, flow agents and the like as are known to those skilled in the art are used in the phase 1 materials of the present invention.

[0034] Phase 2 is a recycled organic material selected from the group unsorted household waste, discarded cellulosic, lignocellulosic, paper, hemp, wood, paint-sludge, biocarbon, carbon-negative filler, ), pyrolyzed paint regrind charr, pyrolyzed paint sludge char or other pyrolyzed paint sludge-based charr, other biologically derived, or organic particle or fiber or mixtures of these. These materials are either added as mechanical reinforcements or they may simply be used as inert fillers which allow the recycling of such materials into a usable injection molding material for use in automotive parts. The phase 2 material in the present invention ranges from about 1 .0 wt.% to about 20.0 wt.%, and preferably from about 5.0 wt.% to about 10 wt.%. The phase 2 material is used as carbon-negative filler to reduce the carbon footprint and / or to increase the recovery rate of the molded part. As stated above the phase 2 filler material may or may not have any benefit to the mechanical performance of the molded part. Use of the phase 2 filler allows the carbon footprint of the manufactured part to be reduced. This increases environmental sustainability, marketing and branding of manufactured automotive or other vehicle parts.

[0035] In a preferred embodiment pyrolyzed char material is used having particle sizes of generally about 2 nm to 3 microns typically 10 to 50 nm and preferably about 15 to 25 nm and still more preferably about 20 nm. Amounts of these materials are used to provide preferred carbon black coloring in amounts of 1 % to about 5% by weight of the final composition to provide the proper color compared to use of virgin carbon blacks.

[0036] An inert protective gas is introduced into the injection molding system. Nitrogen is a preferred gas. The use of nitrogen or other inert gas, such as argon, is injected inside the barrel of the injection molding machine via the hopper, or via an interface that connects a nitrogen cylinder into the barrel of the press. However other methods of injecting inert gas into the injection molding machine are within the scope of the present invention. The flow of nitrogen is controlled via a gas regulator or other device which provides proper inert gas control in the machine to prevent degradation of the phase 2 filler materials. EXAMPLES

[0037] Embodiment 1 , for class A using co-injection molding.

[0038] The core material consists of a 50:50 mixture of UBQ carbon-negative filler (ClimaPos) and class A-compatible TPO, with a total UBQ content of 18.0 wt.% per part. The skin material is class A-compatible TPO typically used in painted bumpers (LBI Hifax CA387A).

[0039] The baseline comprises 100% class A-compatible TPO with zero UBQ. (*) The lower-than-expected results observed are attributed to an increased distance between the robotic paint equipment and the substrate, influenced by the part's geometry rather than directly attributable to the carbon-negative material. This claim is supported by FTIR spectrometer analysis of the painted surfaces, which did not detect any migration of UBQ through the paint coating as shown in Figure 4 (wherein 28 is using UBQ ClimaPos and 26 shows UBQ rich painted spectrometry).

[0040] Embodiment 2, for class A using co-injection molding.

[0041] The core material consists of 7.0 wt.% UBQ carbon-negative filler (MPakt), with a total UBQ content of 7.0 wt.% per part. The skin material is class A-compatible TPO typically used in painted bumpers (WPP 3977 LW P). (*) The lower-than-expected results observed are attributed to an increased distance between the robotic paint equipment and the substrate, influenced by the part's geometry rather than directly attributable to the carbon-negative material. This claim is supported by FTIR spectrometer analysis of the painted surfaces, which did not detect any migration of UBQ through the paint coating. Embodiment 3, for class A using co-injection molding.

[0042] The core material consists of a 50:50 mixture of UBQ carbon-negative (Mpakt) and paint regrind sourced at MAGNA NASCOTE plant. The total UBQ content was 3.5 wt.% plus 3.5 wt.% paint regrind per part. The skin material is class A-compatible TPO typically used in exterior painted panels (WPP 3977 LW P).

[0043] (*) The lower-than-expected results observed are attributed to an increased distance between the robotic paint equipment and the substrate, influenced by the part's geometry rather than directly attributable to the carbon-negative material. This claim is supported by FTIR spectrometer analysis of the painted surfaces, which did not detect any migration of UBQ through the paint coating.

[0044] Embodiment 4, for improving the processing window using standard injection molding and nitrogen flush.

[0045] The base material is a pelletized mixture comprising 40% Long Glass Fiber - PP (40LGF-PP) with 5.0 wt.% UBQ (ClimaPos). 40LGF-PP is commonly used in thermoplastic structural applications such as front-end-modules and active grill systems. The max processing temperature was set at 182°C and the tool temperature was set to 60°C.

[0046] Referring to Figure 5, pure nitrogen 30 was introduced into the feeding throat 32 of the injection-molding machine 34 using a specially designed valve 34 connected to multiple nitrogen-containing cylinders (30a-30d) via a feed line 36. The nitrogen gas flowed at 60 PSI for 5 minutes prior to molding the first samples.

[0047] To evaluate the effectiveness of the nitrogen flush, the odor emitted from the molded samples was assessed by a third-party laboratory. Samples designated for odor testing were wrapped in aluminum foil and vacuum-sealed immediately after molding to preserve their original odor until testing. Additionally, the mechanical performance of samples processed with and without nitrogen flush was compared.

[0048]

[0049] Embodiment 5, for improving the processing window using standard injection molding and a blend of additives. The base material is a pelletized mixture comprising 40% long glass fiber - PP

[0050] (40LGF-PP) and 5.0 wt.% UBQ (ClimaPos). A proprietary blend of antioxidants, costabilizers, and reactive additives was pre-mixed and added to the base material at 1 .0 wt.% or 2.0 wt.% to mitigate thermal-oxidative degradation of the thermally-sensitive carbon-negative filler to widen the processing window (BYK Recyclobyk 4373). The base material contained 0.0 wt.% blend of antioxidants, co-stabilizers and reactive additives.

[0051] The processing max. temperature was set at 182°C and the tool temperature was set to 60°C.

[0052] The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.

Claims

CLAIMSWhat is claimed is:1 . A thermoplastic component for a vehicle formed by two phases comprising a phase 1 material, wherein phase 1 is the thermoplastic matrix component, and a phase 2 material wherein phase 2 is the reclaimed and / or recycled negative carbon footprint filler reinforcement material.

2. The thermoplastic component of Claim 1 wherein phase 1 may be TPO, PP or PA, or other thermoplastic resin used as matrix in reinforced composites, and phase 2 may be unsorted household waste, discarded cellulosic, lignocellulosic, paper, hemp, wood, paint-sludge, pyrolyzed paint sludge, biocarbon, carbon-negative filler, or other biologically derived, or organic particle or fiber.

3. The thermoplastic component of Claim 2 wherein the phase 2 may range from 1 .0 wt.% - 20.0 wt.%, preferably 5.0 wt.% to 10 wt.%.

4. The thermoplastic component of Claim 2 wherein phase 2 is used as carbon-negative filler to reduce the carbon footprint or to increase the recovery rate of the molded part, and where the filler may or may not have any benefit to the mechanical performance of the molded part.

5. The thermoplastic component of Claim 2 wherein phase 2 is used to reduce the carbon footprint and increase environmental sustainability, marketing and branding.

6. The thermoplastic component of Claim 2 wherein the use of nitrogen or other inert gas, such as argon, is injected inside the barrel of the injection molding machine via the hopper, or via an interface that connects a nitrogen cylinder into the barrel of the press.

7. The thermoplastic component of claim 1 wherein a pyrolyzed char material is use having a size range of from about 2 nanometers to 3 microns in amounts of from about 1 to 5% by weight.

8. The thermoplastic component of Claim 6 wherein the flow of nitrogen is controlled via a gas regulator.

9. A process for injection molding of a reduced carbon footprint thermoplastic material comprising the steps of: a. Providing a first phase 1 material which includes a thermoplastic resin; b. Adding a second phase 2 organic waste filler material to said first phase thermoplastic resin; and,c. Injection molding an article from the combination in the presence of an inert gas for attenuation of any thermal degradation of the second organic waste filler during injection molding.

10. The process of Claim 9 wherein phase 1 may be TPO, PP or PA, or other thermoplastic resin used as matrix in reinforced composites, and phase 2 may be unsorted household waste, discarded cellulosic, lignocellulosic, paper, hemp, wood, paint-sludge, biocarbon, carbon -negative filler, or other biologically derived, or organic particle or fiber.11 . The process of Claim 10 wherein the amount of phase 2 organic waste filler material is from about 1.0 wt.% - 20.0 wt.%, and preferably from about 5.0 wt.% to 10 wt.%.

12. The process of Claim 10 wherein the phase 2 organic waste filler material is used as carbon-negative filler to reduce the carbon footprint or to increase the recovery rate of the molded part, and wherein the filler may or may not have any benefit to the mechanical performance of the molded part.

13. The process of Claim 10 wherein the phase 2 organic waste filler material is used to reduce the carbon footprint and increase environmental sustainability, marketing and branding.

14. The process of Claim 10 wherein the use of nitrogen or other inert gas, such as argon, is injected inside the barrel of the injection molding machine via the hopper, or via an interface that connects a nitrogen cylinder into the barrel of the press.

15. The process of Claim 10 wherein the flow of nitrogen is controlled via a gas regulator.

16. The process of claim 9 wherein a pyrolyzed char material is used having a size range of from about 2 nanometers to 3 microns in amounts of from about 1 to 5% by weight.

17. A thermoplastic vehicle component formed by an outer surface layer and a core material for the purpose of using in vehicle exterior trim, exterior panel, or exterior body part with class A surface appearance co injection molded with an outer class A surface layer and a substrate core material which is a carbon negative material.

18. The thermoplastic vehicle component of Claim 17 wherein the outer layer is a class A-capable TPO, or other thermoplastic polyolefin suitable for co-injection molding.

19. The thermoplastic vehicle component of Claim 17 wherein the core material is a carbon-negative filled thermoplastic material, substantially filled with a filler comprising an unsorted household waste (UBQ), paint regrind or paint sludge, or paint sludge-based charror mixtures of these in the range of 3.5 wt.% - 18 wt.%, for the purpose of reducing the carbon footprint and increase the environmental sustainability and circularity of the vehicle part.

20. The thermoplastic vehicle component of Claim 17 wherein the outer class A-surface layer surface capability is measured by wavelength, in the range: Short Wave < 30 @ 23°C, Long Wave < 20 @ 23°C, DOI > 80 @ 23°C, and Orange Peel > 6.0 @ 23°C.21 . The thermoplastic vehicle component of Claim 17 wherein the core material is formed of a thermoplastic component formed by long glass fiber - PP and carbon negative material for the purpose of using as structural reinforcement wherein the core material is a carbon-negative filled thermoplastic material, substantially filled with a filler comprising an unsorted household waste (UBQ), paint regrind or paint sludge, or paint sludge-based charr or mixtures of these in the range of 3.5 wt.% - 18 wt.%, for the purpose of reducing the carbon footprint and increase the environmental sustainability and circularity of the vehicle part.

22. The thermoplastic vehicle component of Claim 17 wherein nitrogen flush is used in combination with the carbon-negative material during molding to gain improvements in odor, HDT and impact strength.

23. The thermoplastic vehicle component of Claim 17 wherein a blend of antioxidants, co-stabilizers, and reactive additives is used in combination with the carbon negative material to reduce the thermal-oxidative degradation as measured by isothermal weight loss at 225°C for 2 h, with the purpose to widen the processing window during molding to achieve gains in odor reduction and increase flexural modulus and impact strength.

24. The thermoplastic vehicle component of Claim 17 wherein a pyrolyzed char material is use having a size range of from about 2 nanometers to 3 microns in amounts of from about 1 to 5% by weight.

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