MATERIALS, COMPOSITIONS, AND METHODS FOR THE FORMATION OF COMPOSITE ARTICLES

Abstract

Provided herein are composite materials comprising a layup consisting of one or more surfacing sheets comingled with a carbon fiber non-woven mat. The surfacing sheet may comprise polyamide-6 and the carbon fiber non-woven mat may comprise carbon fibers that have been recycled. The surfacing sheets comprise sub-micron scale particles for reducing the thermal expansion coefficient of the surfacing sheets. The resulting layup is suitable for use in the formation of articles, particularly articles requiring a smooth finish absent of defects caused by underlying surfaces having irregular compositions or textures.

Claims

1. A composite material comprising a layup consisting of one or more surfacing sheets with a carbon fiber non-woven mat.

2. The composite material of claim 1, wherein the carbon fibers are well-dispersed in the non-woven mat, wherein the non-woven mat has minimal carbon fiber bundles, wherein the fibers are in mostly isotropic in-plane fiber orientation and/or wherein the carbon fibers are in random in-plane orientation.

3. The composite material of claim 2, wherein the non-woven mat contains a high fiber loading (20-40 wt %) of chopped carbon fibers.

4. The composite material of claim 3, wherein the chopped carbon fibers comprise lengths of approximately 5-80 mm, 5-60 mm, 5-40 mm, 5-15 mm, 5-10 mm, or 10 mm.

5. The composite material of claim 4, wherein the carbon fibers comprise recycled carbon fibers or reclaimed carbon fibers.

6. The composite material of claim 5, wherein the carbon fiber non-woven mat has a thickness of approximately 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, or 10 mm.

7. The composite material of claim 6, wherein the one or more surfacing sheets surfacing layer comprises a polymer or compatible polymer that is the same as the polymer in the non-woven mat; for example wherein the one or more surfacing sheets surfacing layer comprises a polyamide-6 when the non-woven mat comprises polyamide.

8. The composite material of claim 7, wherein the one or more surfacing sheets further comprise sub-micron scale particles for reducing the thermal expansion coefficient of the surfacing sheets.

9. The composite material of claim 8, wherein the sub-micron scale particles comprise carbon-based fillers, mineral fillers or nanomaterials.

10. The composite material of claim 9, wherein the surfacing sheet is considered to be resin rich polyamide-6.

11. The composite material of claim 10, wherein the viscosity of the resin rich polyamide-6 comprises injection molding grade of moderate viscosity or extrusion grade viscosity.

12. (canceled)

13. The composite material of claim 1, wherein the surfacing sheet is present as a layer on one surface or both surfaces of the carbon fiber non-woven mat.

14. (canceled)

15. The composite material of claim 1, wherein the surfacing sheet has a thickness in the range of approximately 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, to 10 mm.

16-23. (canceled)

24. The composite material of claim 3, further comprising resin.

25. The composite material of claim 24, wherein the resin comprises a thermoplastic compound or a polymer.

26. The composite material of claim 25, wherein the polymer comprises additives, heat stabilizers, flame retadents, compatibilizers, waxes and/or pigments.

27. A composite material comprising a layup consisting of one or more surfacing sheets with a non-woven mat wherein the non-woven mat comprises fibers.

28. The composite material wherein the fibers comprise carbon fibers, glass fibers and/or natural fibers.

29. The composite material of claim 27, wherein the fibers are well-dispersed in the non-woven mat, wherein the non-woven mat has minimal fiber bundles, wherein the fibers are in mostly isotropic in-plane fiber orientation and/or wherein the fibers are in random in-plane orientation.

30. The composite material of claim 27, wherein the non-woven mat contains a high fiber loading (20-40 wt %) of chopped fibers.

31-57. (canceled)

Description

DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention is described with reference to particular embodiments having various features. It will be apparent to those skilled in the art that various modifications and variations can be made in the practice of the present invention without departing from the scope or spirit of the invention. One skilled in the art will recognize that these features may be used singularly or in any combination based on the requirements and specifications of a given application or design. One skilled in the art will recognize that the embodiments of the invention can be used with any of the methods of the invention and that any methods of the invention can be performed using any of the embodiments of the invention. Embodiments comprising various features may also consist of or consist essentially of those various features. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention. The description of the invention provided is merely exemplary in nature and, thus, variations that do not depart from the essence of the invention are intended to be within the scope of the invention.

[0019] Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as would be commonly understood or used by one of ordinary skill in the art encompassed by this technology and methodologies.

[0021] Texts and references mentioned herein are incorporated in their entirety.

[0022] Provided herein are improved methods and materials that enable the efficient production of fiber reinforced panels having acceptable surface visual quality. The improved methods described herein utilize non-woven preform mats made from comingled recycled carbon fiber (rCF) and polyamide-6 (PA6) fibers for automotive paneling having desirable mechanical and visual qualities.

[0023] To meet panel design criteria, long rCF fibers can be co-mingled with engineering-grade thermoplastic fibers to produce rolls of impregnated non-woven mats readily compression moldable into reinforced panels. This technique is advantageous from a manufacturing sustainability standpoint as the non-woven trimmings can be readily put back through the original mat forming process, virtually eliminating all process scrap. The resulting reinforced thermoplastic panels can themselves also be recycled at end of life: either through regrind for direct remolding or through the same pyrolysis or solvolysis processing used to recover the recycled fiber originally.

[0024] Provided herein are composite materials comprising a layup consisting of one or more surfacing sheets with a non-woven mat wherein the non-woven mat comprise fibers, and wherein the fibers may comprise carbon fibers, glass fibers and/or natural fibers and the like. The fibers may be well-dispersed in the non-woven mat, wherein the non-woven mat has minimal fiber bundles, wherein the fibers are in mostly isotropic in-plane fiber orientation and/or wherein the fibers are in random in-plane orientation. The non-woven mat may contain a high fiber loading (20-40 wt %) of chopped fibers as well as other components such as stabilizer, fillers etc. The chopped fibers comprise lengths of approximately 5-80 mm, 5-60 mm, 5-40 mm, 5-15 mm, 5-10 mm, or 10 mm. The fibers comprise recycled fibers or reclaimed fibers. In various embodiments, the non-woven mat has a thickness of approximately 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, or 10 mm and may be customized according to the application thereof.

[0025] In certain embodiments, the composite material claimed herein may comprise one or more surfacing sheets surfacing layer comprising a polymer or compatible polymer that is the same as the polymer in the non-woven mat. For example, the one or more surfacing sheets surfacing layer may comprise polyamide-6.

[0026] In certain embodiments, the composite materials of the invention comprise one or more surfacing sheets further comprising sub-micron scale particles for reducing the thermal expansion coefficient of the surfacing sheets. The sub-micron scale particles may comprise carbon-based fillers, mineral fillers or nanomaterials. The surfacing sheet may be considered to be resin rich polyamide-6. In addition, the viscosity of the resin rich polyamide-6 may comprise injection molding grade of moderate viscosity; including but not limited to Ultramid® B3. Furthermore, the viscosity of the resin rich polyamide-6 may comprise extrusion grade viscosity; including but not limited to Ultramid® B4.

[0027] In certain embodiments, the non-woven mat further comprises thermoplastic components. The thermoplastic component may comprise the thermoplastic component in any form including thermoplastic fibers or thermoplastic powder.

[0028] The non-woven mat may comprise one or more rigid consolidated sheets. In certain embodiments, the surfacing sheet is present as a layer on one surface of the non-woven mat, or as a layer on both surfaces of the non-woven mat. The surfacing sheet may have a thickness of approximately 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, or 10 mm.

[0029] In certain embodiments, a compression molding tool may be used to mold the layup. The compression molding tool may comprise a positive mold, the compression molding tool may comprise a polished molding surface to impart a smooth finish, the compression molding tool may comprise a configured molding surface to impart a configured finish, and/or the configured molding surface comprises a pattern.

[0030] In certain embodiments, the surfacing sheets and non-woven mat may be manufactured into a molded part as a one step process. The process may further comprise the use of an induction heated tool with rapid cooling. The composite material may be painted using a low-temperature bake paint system.

[0031] In certain embodiments, the composite layup further comprises a resin, the resin may comprise a thermoplastic compound or a polymer. The polymer may comprise additives, heat stabilizers, flame retadents, compatibilizers, waxes and/or pigments.

[0032] The resulting articles may be of various sizes, shapes, and thickness. For example, the articles can be configured to mimic conventional composite articles, such as panels. The article can also be of various complex shapes, such as automotive parts, including but not limited to, header and nose panels, hoods, tailgates and trunk lids, bumpers, doors, fenders, radiator supports and headlight mounts. The article can include one or more layers. For example, if the article is a support structure, the article can include one layer, e.g. a core layer, two layers, e.g. a core layer and a face/fascia layer, or three or more layers, e.g. a core layer and two fascia layers.

[0033] Without being bound or limited to any particular theory, it is thought that presence of the fiber component, such as a carbon fiber component, improves the durability and utility of the composite article. Furthermore, it is thought that the combined presence of the non-woven preform mats made from comingled rCF and polyamide-6 (PA6) fibers enables the resulting composite article to have properties desirable for automotive components and parts.

[0034] The following examples is intended to illustrate and not to limit the disclosure.

EXAMPLES

Non-Woven rCF and Polyamide-6 (PA6) Fiber Preform Mats

[0035] In this study, the potential of non-woven preform mats made from comingled rCF and polyamide-6 (PA6) fibers for automotive paneling was examined by molding test panels via induction heat compression molding. The consolidated rCF/PA6 composite parts were then tested for mechanical and visual surface quality and compared against reference materials currently used by the automotive industry.

Materials & Methodology

[0036] Rolls of co-mingled rCF/PA6 non-woven mat were produced at 40% carbon fiber content by weight as the starting preform material for this study's molding trials. The rolls were produced at an areal density of 350 gsm from chopped recycled carbon fiber and from chopped PA6 fiber supplied by BASF Corp. A surfacing layer was created from PA6 and included 10% by weight carbon black. The surfacing layer was an extruded sheet with a nominal thickness of 1.2 mm Consolidated composite panels for mechanical testing were produced using a Beckwood 100-ton press outfitted with an induction heated compression molding tool from RocTool Inc. For molding, non-woven preforms and surfacing layers were cut to the shape of the mold cavity (approximately 300 mm×500 mm) and hand laid up inside the tool before heating and molding. One surfacing layer was placed on the top and bottom of the stack of non-woven mats to create a symmetric layup. The RocTool induction equipment was set to heat the tool to a nominal molding temperature of ˜260° C., the composite heat soaked for 80 seconds, followed by the application of tonnage for 60 seconds at molding temperature then cooling under tonnage to a demold temperature of 80° C.

[0037] Mechanical test bars (nominally 100 mm×12.5 mm×0.7 mm) were water jet cut from molded parts and subjected to 2 mm/min constant tensile displacement rate tests based on ASTM D3039 [15]. Mechanical testing was conducted using an MTS Criterion 45 UTS load frame with a 100 kN load cell. Specimens for surface quality analysis were cut into test panels approximately 100 mm×300 mm and then painted using a standard BASF automotive painting system for PA6 which utilized a black primer basecoat and a 2K clearcoat. The coatings were cured at a lower bake temperature of 80° C. to minimize part surface topographical changes while still simulating a realistic automotive painting process. The painted surfaces were then scanned with an automotive industry standard BYK Wavescan device to determine relative surface waviness at long and short wavelengths. A BYK Wavescan uses a laser to measure and categorize surface waviness/roughness over 0.1-30 mm. These values can be reported as long wavelength range 1.2-12 mm (LW) and short wavelength range 0.3-1.2 mm (SW) scalar intensities or over a finer structure spectrum: du <0.1 mm, Wa 0.1-0.3 mm, Wb 0.3-1 mm, We 1-3 mm, Wd 3-10 mm, We 10-30 mm [16]. The specific Class A surface definitions vary by automotive OEM, but for the purposes of this study a simple Class A surface threshold was defined as LW<=10 and SW<=20.

Results & Discussion

Mechanical Performance

[0038] The mechanical test specimens yielded a Youngs Modulus of 10.5 GPa and a tensile strength 127.6 MPa. This performance can be explained by the overall averaging of the polyamide resin and carbon fiber content amongst the cross-section of the test specimen. Furthermore, the emphasis to produce short cycle time parts for automotive applications may also contribute to the mechanical performance described here. Nonetheless, this level of performance achieved by the thermoplastic composite is consistent with thermoset SMC technologies used for automotive body panel application.

Painted Surface Quality

[0039] The composite panel was painted alongside a primed cold rolled steel panel typically used for paint evaluation as a benchmark for comparison, in addition to the longwave and shortwave targets. The use of a steel benchmark panel also confirms that this painting trial is consistent with typical painting trials. The painted steel benchmark panel had a longwave value of 5.8 and shortwave value of 12.9 while the carbon fiber composite panel had values of 9.5 and 11.4 for SW and LW, respectively. The surface quality of composite panel is below the target values for SW and LW and is similar to the steel benchmark panel. Furthermore, the surface finish appears smooth with no visible traces of fiber or fiber bundles from the underlying carbon fiber. With these criteria met, it is feasible to say that a carbon fiber/polyamide-6 composite can be produced in a short cycle time and yield a Class A surface finish when painted.

Conclusion

[0040] Reducing weight is an important strategy for improving the fuel economy and range of both electric and traditional vehicles. Fiber reinforced polymer composites offer an attractive weight reduction option for automotive body panel applications by being able to offer needed stiffness, durability, and lower weight. The emergence of rCF as a commercially available form of fiber reinforcement now offers the promise of achieving the benefits of composites at a significantly reduced price point with a more sustainable supply chain. In this example a commercially scalable non-woven consisting of rCF (40 wt %) and PA6 fiber (60 wt %) was molded with the addition of a resin rich surfacing sheet via induction heating to demonstrate its potential for automotive exterior body paneling. Characterization of these panels revealed: [0041] rCF/PA6 paneling was compression moldable into panels via induction heating, resulting in significant reductions in cycle time that approach timings acceptable for automotive mass production, [0042] Painted rCF/PA6 panels exhibited a Class A surface finish despite the existence of carbon fiber and potentially large carbon fiber bundles in the substrate.

[0043] It is to be understood that the appended claims are not limited to express and particular compounds, compositions, or methods described in the detailed description, which may vary between particular embodiments which fall within the scope of the appended claims. With respect to any Markush groups relied upon herein for describing particular features or aspects of various embodiments, it is to be appreciated that different, special, and/or unexpected results may be obtained from each member of the respective Markush group independent from all other Markush members. Each member of a Markush group may be relied upon individually and or in combination and provides adequate support for specific embodiments within the scope of the appended claims.

[0044] It is also to be understood that any ranges and subranges relied upon in describing various embodiments of the present disclosure independently and collectively fall within the scope of the appended claims, and are understood to describe and contemplate all ranges including whole and/or fractional values therein, even if such values are not expressly written herein. One of skill in the art readily recognizes that the enumerated ranges and subranges sufficiently describe and enable various embodiments of the present disclosure, and such ranges and subranges may be further delineated into relevant halves, thirds, quarters, fifths, and so on. As just one example, a range “of from 0.1 to 0.9” may be further delineated into a lower third, i.e., from 0.1 to 0.3, a middle third, i.e., from 0.4 to 0.6, and an upper third, i.e., from 0.7 to 0.9, which individually and collectively are within the scope of the appended claims, and may be relied upon individually and/or collectively and provide adequate support for specific embodiments within the scope of the appended claims. In addition, with respect to the language which defines or modifies a range, such as “at least,” “greater than,” “less than,” “no more than,” and the like, it is to be understood that such language includes subranges and/or an upper or lower limit. As another example, a range of “at least 10” inherently includes a subrange of from at least 10 to 35, a subrange of from at least 10 to 25, a subrange of from 25 to 35, and so on, and each subrange may be relied upon individually and/or collectively and provides adequate support for specific embodiments within the scope of the appended claims. Finally, an individual number within a disclosed range may be relied upon and provides adequate support for specific embodiments within the scope of the appended claims. For example, a range “of from 1 to 9” includes various individual integers, such as 3, as well as individual numbers including a decimal point (or fraction), such as 4.1, which may be relied upon and provide adequate support for specific embodiments within the scope of the appended claims.

[0045] The present disclosure has been described herein in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the present disclosure are possible in light of the above teachings. The present disclosure may be practiced otherwise than as specifically described within the scope of the appended claims. The subject matter of all combinations of independent and dependent claims, both single and multiple dependent, is herein expressly contemplated.

[0046] The United States Government has rights in this invention pursuant to contract no. DE-AC05-000R22725 between the United States Department of Energy and UT-Battelle, LLC.

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