Chopped fiber polymer composites and method to make them

Abstract

A chopped carbon fiber polymer composite (CCFPC) having good mechanical properties may be made by feeding a polymer and a continuous carbon fiber into an extruder, the continuous carbon fiber being fed downstream of the polymer, cutting the continuous carbon fiber within the extruder to form cut carbon fibers, mixing the cut carbon fibers with the polymer forming a mixture, and extruding the mixture through a die to form the CCFPC. The method may be used to make CCFPCs with chopped fibers without any coupling agent. The method may be used to make CCFPCs with thermoplastic polymers with low melt flow rates with high chopped fiber loadings.

Description

CHOPPED FIBER POLYMER COMPOSITES AND METHOD TO MAKE THEMFIELD

[0001] The invention relates to forming chopped fiber polymer composites and method to make them. In particular, it relates to chopped carbon fiber thermoplastic polymer composites and method to make them.BACKGROUND

[0002] Over many years in the transportation industry there has been a continuing shift from the use of metal materials to carbon fiber polymer composites. For example, whole monocoques have been formed of woven carbon fiber polymer composites (e.g., formula 1 racing vehicles). Likewise, fuselages of aircraft have been made of woven carbon fibers. These uses of carbon fiber composites have tended to be used in applications where weight and performance are of paramount importance (e.g., Formula 1 race cars and Aircraft e.g., "Boeing DREAMLINER"). Thermoplastic polymers toughened with chopped carbon fibers (e.g., 10 mm to 50 mm) have been used in the general auto motive industry, for example, as a replacement for certain aluminum components. To realize the necessary loadings of fibers in the plastic matrix sizing has been used on the fibers to ensure compatibility of the carbon fiber and protect the carbon fibers.

[0003] Conventionally, carbon fibers are sized and chopped to lengths of 10 to 50 mm. They may also be milled to less than 1 mm, but composites made from such short fibers tend to have inferior properties. To realize the loading and performance of the chopped fibers in the fiber composites, the fibers have been treated with a sizing composition comprised of a coupling agent. A coupling agent is a molecule that bonds to the carbon fiber surface and with the matrix polymer enhancing the bonding between the matrix polymer and carbon fiber surface. To realize the desired productivity of loading thermoplastic polymers, fiber bundles of larger and larger size have been sought leading to problems of uniform distribution of the sizing composition (see, for example, US. Pat.No. 9,803,066). These sized chopped fibers are then fed to a single or double screw extruder with the thermoplastic polymer and extruded through a die to form pellets, which then may be molded into an article (e.g., injection molding). The consistency and flowability of the bundles of chopped fibers and the flowability of the polymer, may limit the amount of chopped fibers that may be incorporated and their uniformity within the thermoplastic polymer.

[0004] It would be desirable to have a method of forming a chopped carbon-polymer composite avoiding the problems of applying a sizing composition to the carbon fiber and the feeding of chopped carbon fiber bundles into an extruder whilst realizing similar or improved characteristics compared to those made conventionally.SUMMARY

[0005] Applicants have discovered that a chopped carbon fiber polymer composite (CCFPC) may be made by feeding a continuous fiber into an extruder downstream from the insertion of the polymer into the extruder and the continuous fiber is cut within the extruder and extruded through a die to orient and form highly loaded CCFPC which may be directly molded into an article or formed into pellets and molded by injection molding. The method surprisingly may be performed in the absence of a sizing composition and in particular a coupling agent on the surface of the fiber yet realize similar loadings and performance as composites conventionally made with sizing. In addition, it has been discovered that the method may allow for the compounding of the chopped carbon fiber with high molecular weight polymer such as a polyamide having a weight average weight of 1 megadaltons (MDt) with or without sized carbon fibers. The continuous fiber may be a linear bundle of fibers or a woven fabric. The thermoplastic, likewise, may be a continuous fiber (bundle or woven fabric).

[0006] An illustration is a method to form a chopped carbon fiber polymer composite (CCFPC) comprising feeding a polymer into an extruderand a continuous carbon fiber, the continuous carbon fiber being fed downstream of the polymer, mixing and cutting thecontinuous carbon fiber with the polymer forming a mixture, and extruding the mixture through a die to form the CCFPC.

[0007] Another illustration is a CCFPC comprised of chopped carbon fibers in the absence of a sizing composition and in particular in the absence of a coupling agent.

[0008] In a further illustration a CCFPC is comprised of chopped carbon fibers and a polyamide having an average weight average of 1 MDa. It is surprisingly found that such high molecular weight thermoplastic polymers may be compounded in situ cutting of the carbon fibers. The cutting of the fibers within the extruder desirably is by cutting by knife edges passing by each other (e.g., in scissoring manner). Such cutting, without being limited, is believed to be beneficial in realizing the desired size and size distribution (length) of the cut fibers as well as limit damage to the fibers (e.g., fraying and the like, which may cause difficulty in achieving the desired loading of fibers).

[0009] The method and the CCFPCs produced therefrom may be used in any useful application for such composites that take advantage of one or more of its desirable characteristics such as mechanical and tribological properties. The composites may be used for applications in transportation, construction, electronics, appliances, and the like.DESCRIPTION OF THE DRA ING

[0010] Figure 1 is a side view representation of a twin screw extruder useful in the method.

[0011] Figure 2 is a representation of a gear mixer useful in the method viewed down the shaft of the extruder.DETAILED DESCRIPTION

[0012] The explanations and illustrations presented herein are intended to acquaint others skilled in the art with the invention, its principles, and its practical application. The specific embodiments of the present disclosure as set forth are not intended to be exhaustive or limit the scope of the disclosure.

[0013] One or more as used herein means that at least one, or more than one, of the recited components may be used as disclosed. It is understood that the functionality ofany ingredient or component may be an average functionality due to imperfections in raw materials, incomplete conversion of the reactants and formation of by-products.

[0014] The method comprises feeding a polymer and a continuous carbon fiber into an extruder, the continuous carbon fiber being fed downstream of the polymer, cutting the continuous carbon fiber within the extruder to form cut carbon fibers, mixing the cut carbon fibers with the polymer forming a mixture, and extruding the mixture through a die to form the chopped fiber polymer composite. To illustrate the method, Figure 1 depicts a side view of a twin screw extruder 10 comprised of an extruder screw 20, gear mixer 30, die 40, polymer feed port 50, and fiber feed port 60.

[0015] The thermoplastic polymer 55 is fed into the polymer feed port 50, where it is heated to a molten state sufficiently to be extruded. The amount of heating and ultimate temperature realized depending on the particular thermoplastic polymer employed. The molten or flowable polymer then flows to where the fiber 65 (continuous fiber with or without a sizing composition including a coupling agent) is fed through the fiberfeed port 60 into the molten thermoplastic polymer with the feed rate depending, for example, on the extruder screw speed (rpm) and extruder screw flight as well as the melt flow rate of the thermoplastic polymer.

[0016] It has been surprisingly discovered that the method allows for the incorporation of chopped fibers (about 1, 5 or 10 mm to 20, 30, 40 or 50 mm in length) at useful chopped fiber loadings in high molecular weight thermoplastic polymers (e.g., weight average molecular weight "Mw" of at least 500 KDa or 1 MDa to any practicable Mw such as 5 MDa) that typically have a low melt flow rate (MFR). The Mw may be determined by known methods in the art such as gel permeation chromotography. Low melt flow rate herein meaning is less than about 10 or 5 (e.g., 2.16Kg @235 °C [g / lOmin as per ASTM D1238). The method may avoid problems associated with low melt flow rate thermoplastic polymers by reducing the amount of degradation and further shortening of the chopped fibers when processed conventionally. It is understood that some small percentage of the chopped fibers may be outside of the aforementioned range, with suchamounts being negligible (e.g., at most about 3%, 2%, 1% by weight or volume of the fibers).

[0017] Figure 2 illustrates a desirable configuration for cutting the continuous carbon fiber where gear mixer 30 have gear mixer bodies 70, protrusions 80 surprisingly act as knife blades and key holes 90 for placement on the extruder screw shafts not pictured within the extruder body not pictured. The gear mixer bodies 70 may be on any useful shape, but generally it is desirable to have a shape that constricts the mixture of the molten thermoplastic polymer and continuous fiber such that the fibers orient when presented to the protrusions 80 (also referred to herein as knife blades). For example, the cutter bodies 70 may be spheroidal, thus constricting the continuous fibers and thermoplastic polymer to the gap 95 between the gear mixer 30 resulting in the cutting of the continuous fibers in a scissoring cutting action between the knife blades of the gear mixer. Likewise, there may be further cutting of the fibers by the knife blades at the gap between the gear mixer 30 and extruder housing (not pictured) which may include stationary knife blades or protrusion extending from the extruder housing. The knife blades 80 may be orthogonal to the longitudinal extruder direction (along the extruder shaft fitted into key holes 90) or may be oriented at some angle from orthogonal (e.g., 5° to 60° from orthogonal) while still intermeshing (e.g., sliding by each other with a intermesh gap of at most about 1 mm, 500 micrometers, 250 micrometers, 100 micrometers to any practical closeness without causing impingement of the knife blades and is typically at least about 10 micrometers) and cutting the fibers in a scissor like fashion. The gap 95 may be any useful length, but generally is at most about 1 cm, 8 mm, 5 mm to 0.5 or 1 mm. The knife blades 80 extend substantially across the gap 95 without impinging on the cutter bodies 70 and the extrusion body. Typically, the knife blades 80 traverse at least 30% or 50% of the gap to 95%, 90%, 85%, 80% or 75% of the gap 95 and gap between the cutter bodies and the extruder housing (not pictured).

[0018] The intermixing of the continuous fiber and subsequent cutting may beneficially realize a more homogeneous mixture and ability to load the chopped fibers in thermoplastic polymers having low flow rates. This may be due to the penetration ofthe continuous fibers by the thermoplastic polymer within the gap as they are being cut under high shear through the gap. The mixing of the cut fibers and polymer may also allow less damage and further shortening of the cut fibers because of the mixing associated with the in situ cutting of the fibers as described herein and damage that may arise from pre-chopping the fibers and sizing the fiber bundles as well as dispersing and the chopped fibers within the thermoplastic polymer when making such composites conventionally.

[0019] The continuous carbon fiber herein means any carbon fiber that has not been previously chopped to lengths desired when making chopped fiber polymer composites and can be metered into the extruder in a consistent continuous manner. Generally, the fibers may be at least 10 meters, 100 meters, 1000 meters in length or greater with the length dependent on reasonable production run times for a particular product desired. In an illustration, remnant carbon fibers from production of carbon fiber fabric or continuous pultruded carbon fiber composites may be used. Such remnants may be adhered, spliced, tied, stitched, or otherwise attached to create a feed carbon fiber of sufficient length and consistency to realize the chopped fiber composites when performing the method.

[0020] The feed carbon fiber may be further comprised of fibers other than carbon fibers. Other useful fibers that may be used may include any suitable, such as those known in the art with examples, being naturally occurring fibers (e.g., hemp, bamboo, jute, sisal, and coconut) metal fibers and glass fibers. All of the feed fiber may be comprised of carbon fibers, all of the fibers may be carbon fibers, but other fibers may be present in any suitable amount depending on the desired characteristics, but typically are present in an amount of about 1%, 5%, 10% or 20% to about 99%, 95%, 75%, or 50% by volume of the fibers present in the chopped fiber polymer composite.

[0021] The carbon fiber may one that is derived from any material that may be processed into a filament of desired size and carbonized. Typically, for carbon fibers, petroleum based pitches, polyamide or polyacrylonitrile may be used. The production of carbon fibers is well known with the following U.S. Pat. Nos., being illustrative: 3,294,489,3,595,946, and 3,461,082. The fibers may be any useful diameter and typically may be from about 1 micrometer to 20, 50 or 100 micrometers in diameter. Examples of suitable fibers include those available from DowAksa under the tradename AKSAKA and from Toray Industries under the tradename ZOLTEK.

[0022] The continuous carbon fibers may be a unidirectional tow of fibers such as remnants from the production of pultruded polymer fiber composites. The continuous carbon fibers fed into the extruder may be a fabric may be carbon fibers arranged in tows also referred to as rovings or simply fibers are multifilament fibers and may have from 10 to 50,000 individual fibers. The fibers of the fabric may be unidirectional, bidirectional or multidirectional. The fabric may be comprised of stacks of fiber layers which are unidirectional in each layer and the direction of the fibers in each layer are at an angle so long as the fibers in any given direction are longer than the maximum chopped fiber length (i.e., about 1 cm). The fabric may be comprised of any fiber useful in making the chopped carbon fiber polymer composite. The fabric may be woven or non-woven (e.g., felt), knitted, multi-axial (e.g., non-crimped fabric), braided or any useful pattern. The fabric desirably is woven or knitted. In a particular illustration, the carbon fibers may be remnants continuous carbon fiber tows of 10, 20, 50, 100, 1000, to 50,000, 30,000 or 25,000 fiber bundles used to make pultruded thermoplastic or thermoset carbon fiber composites. The fiber tows may be attached or overlapped when feeding into the extruder to ensure a consistent presence of fiber in the extruder.

[0023] The polymer fed into the extruder may be a thermoplastic resin or thermoplastic polymer or thermosetting resin. Resin is used herein to denote that further curing or polymerization may occur within the extruder such as introducing monomers or oligomers of a condensation polymer such as a polyamide and forming the thermoplastic polymer within the extruder (reactive extrusion) along with mixing and cutting the carbon fibers.

[0024] The thermoplastic polymer as described herein generally encompass a plastic material or polymer that is reversible in nature. For example, thermoplastic materials typically become pliable or moldable when heated to a certain temperature and returnsto a more rigid state upon cooling. The thermoplastic materials may include amorphous thermoplastic materials and / or semi-crystalline thermoplastic materials. For example, some amorphous thermoplastic materials may generally include, but are not limited to, styrenes, vinyls, cellulosics, polyesters, acrylics, polysulphones, and / or imides. More specifically, exemplary amorphous thermoplastic materials may include polystyrene, acrylonitrile butadiene styrene (ABS), polymethyl methacrylate (PMMA), glycolised polyethylene terephthalate (PET-G), polycarbonate, polyvinyl acetate, amorphous polyamide, polyvinyl chlorides (PVC), polyvinylidene chloride, polyurethane, or any other suitable thermoplastic material. In addition, exemplary semi-crystalline thermoplastic materials may generally include, but are not limited to polyolefins, polyamides, fluoropolymer, ethyl-methyl acrylate, polyesters, polycarbonates, and / or acetals. More specifically, exemplary semi-crystalline thermoplastic materials may include polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polypropylene, polyphenyl sulfide, polyethylene, polyamide (nylon), polyetherketone, polyolefins and in particular functionalized polyolefins (e.g., anhydride or amino grafted polyolefins) or any other suitable semi-crystalline thermoplastic material. The thermoplastic polymer may comprise blends of thermoplastic polymer such as any one of the aforementioned (e.g., grafted polyolefin and polyamide). The thermoplastic polymer may include thermoplastic elastomers such as copolymers of conjugated dienes and other monomers such as styrene.

[0025] The thermoplastic polymer may include a post-consumer material or a scrap thermoplastic polymer. The thermoplastic polymer may be a fabric, including a textile (e.g., 80% to 95% nylon balance elastomer textiles) and a particular illustration may be a fabric polyamide ply applied to pultruded carbon fiber composites to protect the surface of such pultruded composites that are then peeled from the pultruded composites when used in applications such as ailerons and the like. Such fabrics may be comprised of a residue of the polymer matrix of the pultrude composite such as cured epoxy or polyurethane described herein or other thermoplastic polymer that then may be incorporated into the chopped carbon fiber polymer composite.

[0026] The method is particularly useful when forming a chopped carbon fiber polymer composite comprised of a high weight average molecular weight (Mw) such as those exhibiting a low melt flow rate as described herein. For example, the thermoplastic (e.g., polyamide) may have a Mw of at least 500 KDa, 750 KDa, 900 KDa or 1 MDa to any practicable Mw (e.g., 3 or 5 MDa). Exemplary useful thermoplastic polymers may be comprised of one or more of a polyamide, polyester, polycarbonate, polyamideimide, polyimide, polyacetal or combination thereof. Desirably, the polymer is comprised of one or more of a polyamide, polyester, polycarbonate or polymer blends comprised of these. The condensation polymer may be linear or branched. Desirably, the condensation polymer is linear.

[0027] A useful polyamide may be any of those known in the art and commonly are semi-crystalline as described from col. 4, line 7 to col. 5, line 22 of U.S. Pat. No. 5,391,640, incorporated herein by reference. In particular, the polyamide may be amorphous as described from col. 5, line 23 to col. 8, line 12 of U.S. Pat. No. 5,391,640, incorporated herein by reference. Examples of conventional polyamides include polypyrrolidone (nylon 4), polycaprolactam (nylon 6), polyhexamethylenediamine-adipic acid (nylon 6,6) polyheptanolactam (nylon 7), polycaprylactam (nylon 8), polynonanolactam (nylon 9), polyundecaneolactam (nylon 11), polydodecanolactam (nylon 12), poly(tet- ramethylenediamine-co-oxalic acid) (nylon 4,2), poly(-tetramethylenediamine-co-adipic acid) (nylon 4,6), poly(tetramethylenediamine-co-isophthalic acid) (nylon 4,1), polyhexamethylene azelaiamide (nylon 6,9), polyhexamethylene sebacamide (nylon 6,10), polyhexa- 5 methylene isophthalamide (nylon 6, IP), polymetaxyly-lene adipamide (nylon MXD6), the polyamide of n-dodecanedioic acid and hexamethylenediamine (nylon6.12), the polyamide of dodecamethylenediamine and n-dodecanedioic acid (nylon12.12), as well as copolymers thereof which include: hexamethylene adipamide-caprolactam (nylon 6,6 / 6), hexamethylene adipamide / -hexamethylene- isophthalamide (nylon 6,6 / 6IP), hexa-methylene adipamide / hexamethylene- terephthalamide (nylon 6,6 / 6T), trimethylene adipamide-hexamethy- 15 lene- azelaicamide (nylon trimethyl 6, 2 / 6, 2), and hexa-methylene adipamide-hexamethylene-azelaicamide caprolactam (nylon 6, 6 / 6, 9 / 6) as well as others which are not particularly delineated here. Examples of polyesters include polyethylene terephthalate and other commercial polyesters such as those available from Celanese under the tradename CELANEX. Examples of polycarbonate include those available from Trinseo S.A. under the tradename CALIBRE.

[0028] The thermoset materials as described herein generally encompass a plastic material or polymer that is non-reversible in nature. For example, thermoset materials, once cured, cannot be easily remolded or returned to a liquid state. As such, after initial forming, thermoset materials are generally resistant to heat, corrosion, and / or creep. Example thermoset materials may generally include, but are not limited to, polyesters, polyurethanes including polyurethanes having polyurea, esters, epoxies, or any other suitable thermoset material. Desirably, the polymer is comprised of polyurethane or epoxy. Exemplary thermosetting resins may include those described in U.S. Pat. Nos. 4,604,435 and 4,663,397, and a polyurethane resin-acrylate resin described in U.S. Pat. Appl. No. 2019 / 0375882, each incorporated herein by reference.

[0029] The thermoset may be any suitable such as those known in the art to make fiber polymer composites utilizing a fibrous fabric. The thermoset may have one or more fillers. Illustratively, the adhesive may be comprised of an epoxy, urethane, urea, formaldehyde, acrylate, silicone or any combination thereof.

[0030] Epoxy is an illustration of a suitable thermoset. The epoxy may be any comprised of an epoxy resin and a curing agent. The epoxy adhesive may be one that has a latent curing agent (or "hardner") or is a two-part epoxy where the curing agent and epoxy resin are mixed upon application. Another illustration is two component methacrylate adhesives such as those described by U.S. Pat. Nos. 4,536,546 and 9,657,203 and PCT Appl. No. W02008057414, which may also be comprised of epoxy compounds.

[0031] The epoxy resin may be saturated or unsaturated, aliphatic, cycloaliphatic, aromatic or heterocyclic and may be substituted. The epoxy resin may also be monomeric or polymeric. An extensive enumeration of epoxy resins useful in the present invention isfound in Lee, H. and Neville, K., "Handbook of Epoxy Resins." McGraw-Hill Book Company, New York, 1967, Chapter 2, pages 257-307; incorporated herein by reference. The epoxy resins may be reaction products of polyfunctional alcohols, phenols, cycloaliphatic carboxylic acids, aromatic amines, or aminophenols with epichlorohydrin. A few examples include bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, resorcinol diglycidyl ether, and triglycidyl ethers of para-aminophenols. Other possible epoxy resins include reaction products of epichlorohydrin with o-cresol and, respectively, phenol novolacs. Further epoxy resins include epoxides of divinylbenzene or divinylnaphthalene. It is also possible to use a mixture of two or more epoxy resins. The epoxy resins may be selected from commercially available products such as those under the tradenames D.E.R. and D.E.N. available from Olin Chemical or Syna 21 cycloaliphatic epoxy resin from Synasia.

[0032] The curing agent may be any that has active chemical moiety that is reactive with the epoxy group of the epoxy resin. Any curing agent may be used alone or in combination with other curing agents. The curing agent may be any such as those known in the art. Examples include phenol-containing compounds, amines and combinations thereof. Illustratively, the curing agent may be primary and secondary polyamines and their adducts and polyamides. For example, polyfunctional amines may include aliphatic amine compounds such as diethylene triamine (D.E.H. 20, available from Olin Chemical), triethylene tetramine (D.E.H. 24, available from Olin Chemical), tetraethylene pentamine (D.E.H. 26, available from Olin Chemical), as well as adducts of the above amines with epoxy resins, diluents, or other amine reactive compounds. Aromatic amines such as metaphenylene diamine and diamine diphenyl sulfone, aliphatic polyamines, such as amino ethylpiperazine and polyethylenepolyamine, and aromatic polyamines such as metaphenylene diamine, diamino diphenyl Sulfone, and diethyltoluene diamine, may also be used as the curing agent. The curing agents may contain a sterically hindered amine group wherein an alkyl, cycloalkyl or aralkyl group is in close proximity to the amine group so that it is less reactive than in the case where the alkyl, cycloalkyl or aralkyl group is absent. An example of a curing agent having hindered amine groups are polyetheramines (for example, Jeffamine D-230 available from Huntsman Chemical), isophorone diamine(for example, Vestamin IPD from Evonik), bis(4-amino-3-methylcyclohexyl)methane (for example, Laromin C-260 from BASF). Further exemplary epoxy resins and hardner are described in U.S. Pat. Publ. No. 2010 / 0151138 from paragraph 51 to 86, incorporated herein by reference.

[0033] The epoxy resins may be further comprised of other agents or additives to impart a desired result. For example, a toughener may be added. Examples of toughening agents include rubber particles. Examples and the amounts of toughening agents that may be suitable include those described in paragraphs 20 to 25 of U.S. Pat. Publ. No. 2015 / 0368457, incorporated herein by reference. The amount of additives may be any useful amount. Typically, the amount of additives is from 10% to 70% by volume of the adhesive.

[0034] The chopped carbon fiber polymer composite typically has an amount of fibers sufficient to realize the desired properties and weight desired for an end part. Typically, the amount of fibers is from about 10%, 15%, 20%, 30 or 50% to 70% or 80% by volume of the composite. The composite may be molded into any useful shape such as those that may be produced by extrusion (e.g., sheet, ribbon, tape, tubes, slitted tubes or rods) directly or formed subsequently by a shaping method such as vacuum molding and injection molding. Illustratively, the CCFPC from the extruder may be molded by injection directly or, for example, pellets of the CCFPC from the extruder may be vacuum molded or injection molded. When molding by such subsequent methods a further thermoplastic polymer may be added if desired to realize a desired shape article and characteristics of the shaped article. The further thermoplastic polymer may any of those described herein and may a different one that present in the CCFPC to form a thermoplastic polymer blend in the subsequent shaped CCFPC article. The thermoplastic polymer fed into the extruder, likewise may be a blend of thermoplastic polymers such as those described herein.

[0035] The thermoplastic polymer may also be comprised of other additives for imparting one or more desired characteristics. Examples, of other additives include chain extenders, end capping agents, other non-fibrous fillers such as the fillers such as mica, talc, clay minerals (e.g., kaolin, , bentonite, smectite, montmorillonite), wollastonite,silica, calcium carbonate, glass beads, glass flakes, glass microballoons, molybdenum disulfide, titanium oxide, zinc oxide, antimony oxide, calcium polyphosphate, graphite, barium sulfate, magnesium sulfate, zinc borate, calcium borite, aluminum borate whisker, potassium titanate whisker, and high-molecular compounds. Other additives may include conductivity-imparting materials such as metal-based materials, metallic oxide-based materials, carbon black, and graphite powder; halogen-based flame retardants such as a brominated resin; antimony-based flame retardants such as antimony trioxide and antimony pentoxide; phosphorus-based flame retardants such as polyphosphate ammonium, aromatic phosphate, and red phosphorus; organic acid metallic salt-based flame retardants such as organic metal borate, metal carboxylate, and aromatic sulfonimide metallic salt; inorganic flame retardants such as zinc borate, zinc, zinc oxide, and zirconium compounds; nitrogen-based flame retardants such as cyanuric acid, isocyanuric acid, melamine, melamine cyanurate, melamine phosphate, and nitrogenated guanidine; fluorine-based flame retardants such as PTFE; silicone-based flame retardants such as polyorganosiloxane; metallic hydroxide-based flame retardants such as aluminum hydroxide and magnesium hydroxide; other flame retardants; flame retardant aids such as cadmium oxide, zinc oxide, cuprous oxide, cupric oxide, ferrous oxide, ferric oxide, cobalt oxide, manganese oxide, molybdenum oxide, tin oxide, and titanium oxide; pigments; colorants; lubricants; release agents; compatibilizers; dispersing agents; crystalline nucleus agents such as mica, talc, and kaolin; plasticizers such as phosphate ester; thermal stabilizers (e.g., compounds comprised of copper such as those available under the tradename BRUGGOLEN from L. Bruggemann GmbH & Co. KG, Germany); antioxidants; color protectors; UV stabilizers; fluidity modifiers; foaming agents; antibacterial agents; vibration dampers; and antistatic agents such as polyether esteramide.

[0036] The other additives may include sizing compositions, but surprisingly these are not necessary, such as those known in the art which may include resins of polyurethane, polypropylene, polyethylene, polycarbonate, polyetherimide, siloxane resins, polyketones, polysulfone, polyethersulfone, polyetheretherketone,polyetherketoneketone, polyphenylenesulfide, polyacrylates, polyvinylacetates, polyamide, polyesters, polyetherimide, polyamines, polyimides, epoxy resins, phenoxy resins, melamine resins, urea resins, polyamideimides, polyethersulfones, polyetheretherketones, polyetherketoneketones, polyphenylenesulfides and combinations thereof or precursors thereof that may be polymerized after being contacted with the carbon fiber or upon pultrusion with the polymer of the UCFP composite. The sizing agent or coupling agent may be an epoxy compound or adduct or isocyanate compound or adduct, compound having a terminal alkene and a terminal polar group such as a carboxylic acid or alcohol such as described in U.S. Pat. Nos. 3,957,716; 10,501,605; and 11,118,022, each incorporated herein by reference.

[0037] The amount of other additives may be any useful amount for imparting a desired characteristic of the UCFP composite. Typically, the amount of other additives may be an amount of about 0.1% or 1% to about 50%, 40%, 30% or 20% by volume of the chopped carbon fiber polymer composite.Illustrations

[0038] Illustration 1. A method to form a chopped carbon fiber polymer composite (CCFPC) comprising feeding a polymer and a continuous carbon fiber into an extruder, the continuous carbon fiber being fed downstream of the polymer, cutting the continuous carbon fiber within the extruder to form cut carbon fibers, mixing the cut carbon fibers with the polymer forming a mixture, and extruding the mixture through a die to form the chopped carbon fiber polymer composite.

[0039] Illustration 2. The method of illustration 1, wherein the cutting is by protrusions.

[0040] Illustration 3. The method of either illustration 1 or 2, wherein the extruder is a twin screw extruder and each screw has a gear mixer having protrusions that intermesh cutting the continuous carbon fiber.

[0041] Illustration 4. The method of any one of illustrations 1 to 3, wherein the continuous carbon fiber is comprised of a bundle of fibers having 25 to 50,000 fibers.

[0042] Illustration 5. The method of illustration 4, wherein the bundle is a fiber tow comprised of fibers essentially parallel to each other.

[0043] Illustration 6. The method of illustration 4, wherein the bundle is a fabric of carbon fibers.

[0044] Illustration 7. The method of any one of the preceding illustrations wherein the continuous carbon fiber has a surface comprised of a coupling agent.

[0045] Illustration 8. The method of any one of illustrations 1 to 6, wherein the continuous carbon fiber has no coupling agent.

[0046] Illustration 9. The method of any one of the preceding illustrations wherein the polymer is a thermoplastic polymer.

[0047] Illustration 10. The method of illustration 9, wherein the thermoplastic polymer is comprised of a polyamide.

[0048] Illustration 11. The method of either illustration 9 or 10, wherein the thermoplastic polymer has a weight average molecular weight (Mw) of at least 500 KDa.

[0049] Illustration 12. The method of illustration 11, wherein the Mw is at least 1 MDa.

[0050] Illustration 13. The method of any one of illustrations 1 to 12, wherein the polymer is a thermoplastic polymer and the thermoplastic polymer is a continuous polymer fiber.

[0051] Illustration 14. The method of illustration 13, wherein the thermoplastic continuous polymer fiber is a bundle of fibers.

[0052] Illustration 15. The method of illustration 14, wherein the bundle of fibers is a fiber tow comprised of fibers essentially parallel to each other.

[0053] Illustration 16. The method of illustration 14, wherein the bundle of fibers is a fabric.

[0054] Illustration 17. The method of any one of the preceding illustrations wherein one or more of the carbon fiber and polymer are comprised of one or more of a post-consumer material and scrap material.

[0055] Illustration 18. The method of any one of the preceding illustrations wherein, the cut carbon fibers comprise at least 15% to 80% by volume of the CCFPC composite.

[0056] Illustration 19. The method of illustration 18, wherein the cut carbon fibers comprise at least 30% by weight of the CCFPC.

[0057] Illustration 20. The method of anyone ofthe preceding illustrations further comprising molding the CCFPC into a CCFPC shaped article.

[0058] Illustration 21. The method of illustration 20, wherein the polymer is a thermoplastic polymer and the molding comprises adding a further thermoplastic polymer.

[0059] Illustration 22. The method of illustration 21, wherein the further thermoplastic polymer is comprised of a thermoplastic polymer that is different than the thermoplastic polymer of the CCFPC.

[0060] Illustration 23. The method of any one of the preceding illustrations, wherein the thermoplastic polymer is comprised of one or more of a polyamide, polyimide, polyamideimide, polyester, polyetherester, thermoplastic polyurethane, polyacrylate, polyacrylic acid, polyolefin, grafted polyolefin or mixture thereof.

[0061] Illustration 24. The method of illustration 23, wherein the thermoplastic polymer is comprised of a polyamide.

[0062] Illustration 25. The method of illustration 24, wherein the polyamide is comprised of one or more of polypyrrolidone (nylon 4), polycaprolactam (nylon 6), polyheptanolactam (nylon 7), polycaprylactam (nylon 8), polynonanolactam (nylon 9), polyundecaneolactam (nylon 11), polydodecanolactam (nylon 12), poly(tet- ramethylenediamine-co-oxalic acid) (nylon 4,2), poly(-tetramethylenediamine-co-adipic acid) (nylon 4,6), poly(tetramethylenediamine-co-isophthalic acid) (nylon 4,1), polyhexamethylene azelaiamide (nylon 6,9), poly(hexylmethylene diamine-adipic acid), polyhexamethylene sebacamide (nylon 6,10), polyhexa- 5 methylene isophthalamide (nylon 6, IP), polymetaxyly-lene adipamide (nylon MXD6), the polyamide of n-dodecanedioic acid and hexamethylenediamine (nylon 6,12), the polyamide ofdodecamethylenediamine and n-dodecanedioic acid (nylon 12,12), as well as copolymers thereof which include: hexamethylene adipamide-caprolactam (nylon 6,6 / 6), hexamethylene adipamide / -hexamethylene-isophthalamide (nylon 6,6 / 6IP), hexa-methylene adipamide / hexamethylene-terephthalamide (nylon 6,6 / 6T), trimethylene adipamide-hexamethy- 15 lene-azelaicamide (nylon trimethyl 6, 2 / 6, 2), and hexa-methylene adipamide-hexamethylene-azelaicamide caprolactam (nylon 6, 6 / 6, 9 / 6).

[0063] Illustration 26. The method of any one of illustrations 20to 25, wherein the CCFPC is a pellet that is mixed with the further thermoplastic polymer at a temperature above where the thermoplastic polymer and further thermoplastic polymer melt and the molding is by injection molding.

[0064] Illustration 27. A chopped carbon fiber polymer composite (CCFPC) comprising a thermoplastic polymer having a weight average molecular weight average (Mw) of at least 500 KDa and chopped carbon fibers without any coupling agent.

[0065] Illustration 28. The CCFPC of illustration 27, wherein the chopped carbon fibers have a length from 1 mm to 20 mm.

[0066] Illustration 29. The CCFPC of either illustration 27 or 28, wherein the thermoplastic polymer is comprised of a polyamide.

[0067] Illustration 30. The CCFPC of any one of illustrations 27 to 28, wherein the thermoplastic polymer is comprised of one of more of nylon 6 and nylon 6,6.Examples

[0068] A Werner-Pfleiderer co-rotating, twin-screw extruder, 30-millimeter diameter, 1152mm long (38:1 L / D), double vented, 20 HP motor, throughput up to 45 Ibs. / hour, fitted with 2 volumetric continuous feeder systems (fibers and ribbons); and a gravimetric feeder is used to compound 66 polyamide and carbon fiber. Strands are cast into a water bath to cool and then cut using a rotary knife pelletizer. The pellets are dried using a dehumified dryer. ISO test specimens (ISO 527-1) are formed by injection molding the dried pellets.

[0069] The polyamide is a 123 mm wide 6,6 polyamide ribbon of varying lengths (peel ply used to protect carbon fiber tows), which is fed at the front end of the extruder. The carbon fibers are 30K fiber tows available from DowAksa that are spliced together tailings from the production of carbon fiber that are introduced slightly past the halfway point from the front end to the die of the extruder. The extruder has 5 zones of essentially equal length. The temperature of the zones from front to the die end (1-5) are zone 1: 500 °F, zone 2: 520 °F, 540 °F, 550 °F, and 570 °F and the screw is rotated from 50 and 100 rpm. The gear mixer is on the extruder shafts just after the point of insertion of the carbon fiber. Three Examples A, B and C are made as shown in Table 1, with the throughput of the feeds shown. The carbon fiber loading is determined by ISO 3451 and corresponds with the input shown in Table 1.Table 1:

[0070] The nominal loading as tested is ~40% for Examples A and C and ~20% by weight or Example B. The testing results of Examples A, B and C are shown in Table 2 as well as commercially available chopped carbon fiber - 6,6 Nylon composite available from BASF with the designation A3WC8 (Comparative Example 1).

[0071] From the data of Table 2, it is apparent that improved or equivalent performance may be obtained by composites made by the method of the invention compared to conventional made composites using pristine polymers and prechopped sized carbon fibers. That is, it surprising the exemplary composites made with carbon fibers that are not sized or prechopped and using post-consumer thermoplastic polymersrealize equivalent or improved performance compared to conventionally prepared composites having similar density and fiber loading.

[0072] Examples B and C and Comparative Example 1 are conditioned to examine the effect of moisture on the properties. Samples of each of these are conditioned for 72 hours at 50% relative humidity at room temperature and then tested. The results are shown in Table 3, which also shows that the lack of sizing results in retained properties as good or better than the comparative exampleTable 2Table 3

Claims

CLAIMSWhat is claimed is:

1. A method to form a chopped carbon fiber polymer composite (CCFPC) comprising feeding a polymer and a continuous carbon fiber into an extruder, the continuous carbon fiber being fed downstream of the polymer, cutting the continuous carbon fiber within the extruder to form cut carbon fibers, mixing the cut carbon fibers with the polymer forming a mixture, and extruding the mixture through a die to form the chopped carbon fiber polymer composite.

2. The method of claim 1, wherein the cutting is by protrusions.

3. The method of claim 2, wherein the extruder is a twin screw extruder and each screw has a gear mixer having protrusions that intermesh cutting the continuous carbon fiber.

4. The method of claim 1, wherein the continuous carbon fiber is comprised of a bundle of fibers having 25 to 50,000 fibers.

5. The method of claim 4, wherein the bundle is a fiber tow comprised of fibers essentially parallel to each other.

6. The method of claim 4, wherein the bundle is a fabric of carbon fibers.

7. The method of claim 1, wherein the continuous carbon fiber has a surface comprised of a coupling agent.

8. The method of claim 1, wherein the continuous carbon fiber has no coupling agent.

9. The method of claim 1, wherein the polymer is a thermoplastic polymer.

10. The method of claim 9, wherein the thermoplastic polymer is comprised of a polyamide.

11. The method of claim 10, wherein the thermoplastic polymer has a weight average molecular weight (Mw) of at least 500 KDa.

12. The method of claim 11, wherein the Mw is at least 1 MDa.

13. The method of claim 1, wherein the polymer is a thermoplastic polymer and the thermoplastic polymer is a continuous polymer fiber, sheet or combination thereof.

14. The method of claim 13, wherein the thermoplastic polymer is a bundle of fibers.

15. The method of claim 14, wherein the bundle of fibers is a fiber tow comprised of fibers essentially parallel to each other.

16. The method of claim 14, wherein the bundle of fibers is a fabric.

17. The method of claim 1, wherein one or more of the carbon fiber and polymer are comprised of one or more of a post-consumer material and scrap material.

18. The method of claim 1 wherein, the cut carbon fibers comprise at least 15% to 80% by volume of the CCFPC.

19. The method of claim 18, wherein the cut carbon fibers comprise at least 30% by volume of the CCFPC.

20. The method of claim 1 further comprising molding the CCFPC into a CCFPC shaped article.

21. The method of claim 20, wherein the polymer is a thermoplastic polymer and the molding comprises adding a further thermoplastic polymer.

22. The method of claim 21, wherein the further thermoplastic polymer is comprised of a thermoplastic polymer that is different than the thermoplastic polymer of the CCFPC.

23. The method of claim 1, wherein the polymer is a thermoplastic polymer comprised of one or more of a polyamide, polyimide, polyamideimide, polyester, polyetherester, thermoplastic polyurethane, polyacrylate, polyacrylic acid, polyolefin, and grafted polyolefin.

24. The method of claim 23, wherein the thermoplastic polymer is comprised of a polyamide.

25. The method of claim 24, wherein the polyamide is comprised of one or more of polypyrrolidone (nylon 4), polycaprolactam (nylon 6), polyheptanolactam (nylon 7), polycaprylactam (nylon 8), polynonanolactam (nylon 9), polyundecaneolactam (nylon 11), polydodecanolactam (nylon 12), poly(tet-ramethylenediamine-co-oxalic acid) (nylon 4,2), poly(-tetramethylenediamine-co-adipic acid) (nylon 4,6), poly(tetramethylenediamine-co-isophthalic acid) (nylon 4,1), polyhexamethylene azelaiamide (nylon 6,9), poly(hexylmethylene diamine-adipic acid), polyhexamethylene sebacamide (nylon 6,10), polyhexa- 5 methylene isophthalamide (nylon 6, IP), polymetaxyly-lene adipamide (nylon MXD6), the polyamide of n-dodecanedioic acid and hexamethylenediamine (nylon 6,12), the polyamide of dodecamethylenediamine and n- dodecanedioic acid (nylon 12,12), as well as copolymers thereof which include: hexamethylene adipamide-caprolactam (nylon 6,6 / 6), hexamethylene adipamide / -hexamethylene-isophthalamide (nylon 6,6 / 6IP), hexa-methylene adipamide / hexamethylene-terephthalamide (nylon 6,6 / 6T), trimethylene adipamide- hexamethy- 15 lene-azelaicamide (nylon trimethyl 6, 2 / 6, 2), and hexa-methylene adipamide-hexamethylene-azelaicamide caprolactam (nylon 6, 6 / 6, 9 / 6).

26. The method of any one of claims 20 to 25, wherein the CCFPC is a pellet that is mixed with the further thermoplastic polymer at a temperature above where thethermoplastic polymer and further thermoplastic polymer melt and the molding is by injection molding.

27. A chopped carbon fiber polymer composite (CCFPC) comprising a thermoplastic polymer having a weight average molecular weight average (Mw) of at least 500 KDa and chopped carbon fibers without any coupling agent.

28. The CCFPC of claim 27, wherein the chopped carbon fibers have a length from 1 mm to 50 mm.

29. The CCFPC of either claim 27 or 28, wherein the thermoplastic polymer is comprised of a polyamide.

30. The CCFPC of any one of claims 27 to 28, wherein the thermoplastic polymer is comprised of one of more of nylon 6 and nylon 6,6.

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