Dual tapered fiber-containing particles

Abstract

The recycled carbon fibers are processed by rotary tumbling in a mixture with a binder material to prepare fiber-containing particles having a dual tapered shape and fibers generally aligned along the length of the fiber-containing particles. The bulk products comprising the fiber-containing particles are composited with a polymer and pelletized to prepare fiber-reinforced composite pellets, which are useful for applications such as injection molding to create carbon fiber reinforced composite articles with recycled carbon fibers.

Description

[Technical field]

[0001] The present invention relates to packaging fibers, in particular recycled carbon fibers, into fiber-containing particles. The invention comprises a method for preparing the particles, a bulk product comprising the particles, and a method of use for preparing fiber-reinforced composite materials. [Background technology]

[0002] (Statement Regarding Federally Sponsored Research and Development) This invention was made with Government support under award DE-EE0006926 from the U.S. Department of Energy. The Government has certain rights in this invention.

[0003] Carbon fiber and other fibers are used in various reinforcement applications to provide enhanced material properties by combining the fibers with a matrix, often a polymer matrix, to provide reinforcement to the matrix material. Fiber-reinforced polymer composites are often referred to by the acronym FRP. Carbon fiber-reinforced polymer composites are sometimes referred to by the acronym CFRP. Due to the commercial value of reinforcing fibers and environmental and landfill considerations, there has been great interest in developing processes to recover and reuse the reinforcing fibers. This is especially the case for carbon fiber, due to the high cost of virgin carbon fiber. A significant amount of the produced CFRP is never used and ends up as waste. For example, in CFRP applications, it is common for material off-cuts and scrap to be approximately 30% or more of the finished part weight. Also, the use of CFRP products has been growing rapidly for several years, so it is expected that the need to address the end-of-life issue of CFRP products will rapidly increase.

[0004] CFRP composites that can be supplied to recycling businesses come in a variety of forms and compositions. Some CFRP composites that can be supplied to recycling are in the form of prepregs with a matrix of thermosetting polymer resin, while others are in the form of cured products in which a cross-linked matrix is ​​formed by the hardening of the thermosetting polymer resin. There are also CFRP composites with a thermoplastic polymer matrix, and CFRP composites using engineering polymers that are not classified as either thermoplastic or thermosetting have also been developed.

[0005] A variety of different processes have been developed and are still being developed to free the carbon fibers from the matrix of CFRP products and allow the fibers to be recovered and recycled. Some processing techniques for freeing the carbon fibers from the matrix are sometimes called pyrolysis, which involves exposing the CFRP to high temperatures, typically in an oxygen-free or oxygen-limited environment, to break down the matrix into gaseous and / or liquid decomposition products without destroying the carbon fibers. Other processing techniques, sometimes called depolymerization techniques, involve the use of chemicals to react with the matrix material to break it down into decomposition products from which the fibers can be separated. Other processing techniques, sometimes called solvolysis techniques, involve the use of solvents to dissolve the matrix material and free the fibers for recovery. Combinations of these techniques may also be used.

[0006] Virgin carbon fibers are typically prepared in the form of continuous fiber strands, whereas the majority of recycled carbon fibers are and will continue to be made available primarily in the form of discontinuous, relatively short fibers with highly random orientation and entanglement of the individual fibers. One common technique for preparing virgin carbon fibers for incorporation into CFRP composites is to prepare a bundle of parallel continuous fiber strands, such as in the form of a fiber tow, and then chop the bundle into pellets of the desired length. The fibers may be held in the bundle by fiber sizing previously applied to the bundle (e.g., a sized tow). Pellets prepared by chopping fiber tow bundles are sometimes called chopped tow pellets. Such pellets can be prepared in a size and shape convenient for feeding into a compound extruder, for example, by feeding from a hopper into a side feeder into a twin-screw extruder. A typical side feeder includes a feed screw that actively pushes pellets into the polymer melt in the extrusion barrel. The extrudate, which includes the polymer and carbon fibers, is cooled and chopped into pellets of CFRP material. These pellets can be used in a variety of applications, such as injection molding, and to prepare a variety of product shapes made of CFRP composites. The ability to process virgin carbon fiber in the form of a bundle of continuous fiber strands allows for tight processing control to prepare pellets of uniform size and composition. It also has good properties of flowability during bulk handling and good dispersion of the fibers in the polymer melt during compounding. However, these techniques for processing virgin carbon fiber are generally not applicable to the processing of the majority of recycled carbon fibers, which tend to be in a non-continuous form and have highly random carbon fiber orientation and fiber entanglement after being recovered during recycling operations. Thus, there is a significant need for alternative techniques that allow for the widespread use of recycled carbon fibers to prepare CFRP composites. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] US Patent Application Publication No. 2019 / 054707 [Patent Document 2] U.S. Pat. No. 10,487,191 [Patent Document 3] U.S. Pat. No. 1,061,0911 [Patent Document 4] U.S. Pat. No. 1,082,9611 Summary of the Invention [Problem to be solved by the invention]

[0008] As mentioned above, recycled carbon fibers are typically collected as relatively short and non-continuous fiber lengths. As a result, they have a high degree of random fiber orientation, as well as a high degree of fiber entanglement and a tendency to form cotton-ball-like clumps. As a result, they cannot be effectively handled or processed using conventional equipment and techniques designed for use with flowable powders and other bulk materials. Recycled carbon fibers have a high tendency to form bridges by sticking together in clumps, for example, which can block the flow from the hopper to the feeder or compound extruder.

[0009] Conventional pellet milling was attempted to prepare pre-mixed masterbatch pellets of recycled carbon fiber with polymers, but with limited success. Recycled carbon fiber only yielded marginally functional masterbatch pellets that could be successfully mixed with polymers when the recycled fiber was milled to a size of approximately 150 microns. Longer fibers with higher aspect ratios are desirable for improved performance as polymer reinforcement. However, masterbatch pellets made with longer recycled fibers were found to have poor mechanical performance in polymer compounds. The pellets were too dense to allow for effective defibration and dispersion of the carbon fiber during extrusion to form the CFRP composite. Thus, injection molded test forms had inconsistent fiber loading. [Means for solving the problem]

[0010] The methods and products disclosed herein are intended to at least partially significantly address the problems associated with incorporating recycled carbon fibers into CFRP composites and producing molded articles from such CFRP composites. Although the methods and products disclosed herein are described primarily with reference to carbon fibers, the disclosure also applies to other fibers, including other recycled fibers. The methods and products disclosed herein are also made applicable to processing virgin fibers that are processed in the form of relatively short fibers rather than in a continuous form. Such non-continuous virgin fibers may be a direct result of the manufacturing process and / or may be fibers cut from continuous fiber strands. The methods and products disclosed herein are particularly advantageous for use with recycled fibers, such as recycled carbon fibers, which are typically recovered in a non-continuous fiber form and have a high degree of randomness in fiber orientation and fiber entanglement, as well as making the use of recycled fibers to prepare fiber-reinforced polymers difficult to process subsequently.

[0011] A first aspect of the present disclosure is directed to a fiber-containing particle comprising reinforcing fibers bound in a particle structure having an elongated dual-tapered shape. Such a fiber-containing particle may include: A majority by weight, preferably 90 weight percent to 99.5 weight percent, of reinforcing fibers; A minor portion by weight, preferably 0.5 weight percent to 10 weight percent, of a binder that holds the reinforcing fibers within the particle structure; a particle length dimension, preferably in the range of 3 millimeters to 40 millimeters, said particle length dimension being the maximum longitudinal separation between first and second longitudinal ends of said fiber-containing particle; a maximum particle width dimension transverse to the longitudinal direction at a longitudinal location between the first and second longitudinal ends; an aspect ratio equal to the particle length dimension divided by the maximum particle width dimension, the aspect ratio being greater than 1, and preferably at least 1.5; and a dual taper shape including a first taper portion tapering toward the first longitudinal end and away from the longitudinal location, and a second taper portion tapering toward the second longitudinal end and away from the longitudinal location; The fiber-containing particles may include

[0012] Such fiber-containing particles prepared by using recycled carbon fibers have been found to promote flowability of bulk products having fiber-containing particles fed from a conventional hopper, such as a vibratory loss-in-weight hopper, through an extrusion feeder to a compounding extruder to prepare carbon fiber reinforced polymer composites having carbon reinforcing fibers provided by the fiber-containing particles dispersed in a polymer matrix. The fiber-containing particles provide an advantageous combination of adequate flowability for handling the bulk product and maintaining sufficient particle integrity during normal handling and processing operations up to the feed hopper during compounding operations. The fiber-containing particles are then degraded from the particle structure by shear exerted from the side screw feeder into the extruder barrel and the polymer melt during extrusion processing to provide an extrudate having reinforcing fibers adequately dispersed in the extruded polymer. The dual tapered particle structure allows for convenient incorporation of fibers of various lengths into the fiber-containing particles for beneficial use in fiber reinforced applications. Moreover, the dual tapered shape is characterized by a significant degree of alignment of the longitudinal direction of the fibers with the longitudinal direction of the fiber-containing particles. This is believed to contribute greatly to improved flowability in bulk product form and improved dispersion of the fibers from the particles to the polymer melt in the polymer blend for preparing fiber-reinforced polymer composites. By achieving such a significant degree of fiber orientation, the randomness of the fiber orientation is significantly reduced, which has the great advantage of reducing the protrusion of the fibers perpendicular to the longitudinal direction from the fiber-containing particles and reducing inter-particle entanglement that may impair the flowability of the bulk product. Rather, the dual tapered shape and the characteristic significant alignment of the fibers with the longitudinal direction of the fiber-containing particles not only facilitate the sliding of the fiber-containing particles in the bulk product, even when the fiber-containing particles having the dual tapered shape are mixed with other particles in the bulk product, but also contribute to the flowability and generally impart sliding properties to the bulk product.With respect to dispersion of the fibers in the polymer melt during polymer compounding, significant alignment of the fibers in the dual tapered geometry of the fiber-containing particles promotes reduced entanglement of the fibers as the particles break down during polymer compounding, thus facilitating improved dispersion of the fibers in the polymer melt during polymer compounding, for example in an extruder.

[0013] A second aspect of the disclosure is directed to a bulk product comprising a plurality of fiber-containing particles, preferably a plurality of fiber-containing particles of the first aspect. Such bulk products may or may not comprise other particles in addition to the fiber-containing particles of the first aspect. Such other particles may include particles prepared together with the fiber-containing particles of the first aspect, for example, by using the method of the third aspect summarized below, but lacking the development of a dual taper shape or other characteristic or property characteristic of the fiber-containing particles of the first aspect. The bulk product may consist of or essentially consist of fiber-containing particles prepared together with the fiber-containing particles of the first aspect, for example, as prepared by the process of the third aspect summarized below, even though some of those fiber-containing particles may not have the dual taper shape or another characteristic or property characteristic of the fiber-containing particles of the first aspect. Such other particles may alternatively or additionally comprise particles not prepared together with the fiber-containing particles of the first aspect, for example, particles blended with the fiber-containing particles after preparation of the fiber-containing particles of the first aspect. Such blended particles may or may not also include fibers, and if such blended particles include fibers, the fibers may or may not be of the same type (e.g., carbon fiber) as the fibers of the fiber-containing particles of the first aspect. For example, the fiber-containing particles may be blended with conventional chopped tow pellets or other fiber-containing pellets. In some preferred embodiments, the bulk product of this second aspect includes a majority (greater than 50 weight percent) of the fiber-containing particles of the first aspect, or even a greater proportion of the fiber-containing particles. When referring to a bulk product including a plurality of fiber-containing particles of the first aspect, the characteristics described for those fiber-containing particles apply to those fiber-containing particles in the bulk product, but do not necessarily apply to other particles in the bulk product that do not have the dual tapered shape or other characteristics of the fiber-containing particles.As discussed above, bulk products having fiber-containing particles with a first side having a dual tapered shape exhibit the advantageous combination of promoting enhanced flowability for handling prior to compounding, while exhibiting enhanced dispersion of the reinforcing fibers from the particles into the polymer melt during extrusion processing to compound the fibers with the polymer matrix.

[0014] A third aspect of the present disclosure is directed to a method of producing fiber-containing particles, such as those of the first aspect, where the fiber-containing particles may be recovered in or subsequently incorporated into the bulk product of the second aspect. The method comprises tumbling a mixture of reinforcing fibers (e.g. recycled carbon fibers) and a binder material to form aggregates comprising the reinforcing fibers and the binder material. Such aggregates may be recovered or further processed to prepare the fiber-containing particles of the first aspect in their final form, which may be in the form of the bulk product of the second aspect. Such a method of the third aspect may comprise processing a fiber feed and a binder material to prepare the fiber-containing particles comprising fibers from the fiber feed, where the fiber feed comprises reinforcing fibers in a non-continuous form. The processing comprises:

[0015] Rotary tumbling the mixture of reinforcing fibers and binder material to form aggregates comprising a portion of the reinforcing fibers and a portion of the binder material. As can be seen, the fiber-containing particles produced by the method of the third aspect do not have the extremely high level of uniformity in size, shape, and fiber orientation of conventional chopped tow pellets prepared by processing bundles of continuous virgin fibers. Surprisingly, the rotary tumbling process of the method of the third aspect can be advantageously used to prepare a batch of fiber-containing aggregates, many or most of which will have the desired dual tapered shape, so that the longitudinal direction of the aggregates is aligned to a significant degree with the longitudinal direction of the fibers. During rotary tumbling, the highly random fiber orientation in the recycled fiber supply, with fibers of different lengths, is transformed into a much more aligned configuration of fibers. Thus, the more aligned fibers are incorporated into the aggregates having a dual tapered shape. Such aggregates may be recovered for use as the fiber-containing particles of the first aspect and the bulk product of the second aspect, or may be further processed to prepare final fiber-containing particles that retain the dual tapered shape with significant alignment of the fibers. Such further processing may include, for example, drying to remove residual processing liquids, typically water, to improve particle integrity, and to remove liquids that may detrimentally volatilize during the high polymer melt temperatures encountered during polymer extrusion during blending, and may include other processing steps as described below.

[0016] A fourth aspect of the present disclosure is directed to a method for producing a fiber reinforced composite material. The method comprises dispersing reinforcing fibers in a matrix from fiber containing particles, for example from fiber containing particles of the first aspect having a dual tapered shape. The fiber containing particles may result from production by the method of the second aspect by being provided in the bulk product of the second aspect. Such a fiber reinforced composite material may be a fiber reinforced polymer, where the matrix is ​​a polymeric material. When the matrix is ​​a polymeric material, the method of the fourth aspect may include compounding the reinforcing fibers from the fiber containing particles with a polymer for the matrix, for example by extrusion, where the fibers are dispersed in a polymer melt in an extruder. The extrudate, comprising the reinforcing fibers of the first aspect dispersed in a polymer matrix, may be pelletized and the pellets may be used to prepare a molded article form in a molding operation, for example by injection molding. Such pellets may be used directly as a feed to a mold, preferably an injection mold. Alternatively, the final fiber reinforced polymer composition may be used as a masterbatch by further blending with or diluting in a compatible polymer to prepare a final fiber reinforced polymer composition having a desired level of fiber loading lower than the fiber loading in the masterbatch, which is then used as a feed for a molding process, preferably an injection molding process.

[0017] These and other aspects are further described in the following description, the appended claims, and the figures. Moreover, numerous feature refinements and additional features are made applicable to these aspects, and these feature refinements and additional features may be used individually or in any combination within the subject matter of the first aspect or any other aspect of the present disclosure. Thus, each of the features described in the following description, included in the numbered example combinations and the appended claims, and / or illustrated in the drawings, may be, but need not be, used with other features or feature combinations of any aspect of the present disclosure. [Brief description of the drawings]

[0018] [Figure 1] 1 illustrates a characteristic of an exemplary fiber-containing particle of the present disclosure having a dual tapered shape. [Diagram 2] 1 illustrates another exemplary fiber-containing particle of the present disclosure having a dual tapered shape. [Diagram 3] FIG. 1 is a generalized flow diagram illustrating several exemplary processes for making fiber-containing particles of the present disclosure. [Figure 4] FIG. 2 is a generalized illustration showing internal baffles within a rotatable processing vessel, illustrated in the form of a rotating drum. [Diagram 5] FIG. 4 is a generalized flow diagram illustrating some exemplary optional pre-processing steps within the general process of FIG. 3. [Figure 6] A generalized process diagram showing some examples of optional subsequent processes within the general process of FIG. 3. [Figure 7] FIG. 1 is a generalized flow diagram illustrating several exemplary processes comprising the preparation of bulk products of the present disclosure. [Figure 8] A generalized flow diagram illustrating several exemplary optional composite preparation processes within the general process of FIG. 7. [Figure 9] FIG. 8 is a generalized flow diagram illustrating several exemplary optional regeneration (recycling) processes for providing a back-up supply of fibers within the general process of FIG. 7. [Figure 10] 1 is a photographic image of an example feed of recycled carbon fiber, the recycled carbon fiber having a high degree of randomness of orientation in a cotton ball structure. [Figure 11] 1 is a photographic image of two different example batches of fiber-containing particles made using recycled carbon fiber, the different batches prepared from recycled carbon fiber being cut to different lengths and resulting in fiber-containing particles of different sizes. [Figure 12] 1 is a photographic image of a bulk product having an example batch of fiber-containing particles in a beaker. [Figure 13] Photographic image looking down on the bulk product of FIG. [Figure 14]Photographic image of a fiber-containing particle showing a well-developed dual tapered shape as well as alignment of the fibers along the longitudinal direction of the particle. [Figure 15] A photographic image showing the inside of a rotating drum having aggregates comprising recycled carbon fibers. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The features illustrated in the drawings are illustrated to aid in the explanation and understanding of features applicable to various aspects of the present disclosure, and the features illustrated in the drawings are not necessarily to scale or in detail in all respects.

[0020] FIG. 1 illustrates the characteristics of a fiber-containing particle of the present disclosure. As shown in FIG. 1, the fiber-containing particle 100 has an elongated configuration having a first longitudinal end 102 and a second longitudinal end 104, and a longitudinal direction 106 between the first longitudinal end 102 and the second longitudinal end 104. The longitudinal direction 106 generally coincides with the longitudinal axis of the fiber-containing particle 100. However, it should be understood that while the fiber-containing particles of the present disclosure have elongated characteristics, fiber-containing particles such as the fiber-containing particle 100 are generally not symmetrical about such longitudinal axis, as such particles are not perfectly symmetrical about a central axis as a result of the manufacturing process. The fiber-containing particle 100 has a particle length dimension 108, which is the linear distance between the first longitudinal end 102 and the second longitudinal end 104. As can be seen, the particle length dimension 108 represents the maximum separation distance in the longitudinal direction 106 between the first longitudinal end 102 and the second longitudinal end 104. The fiber-containing particle 100 also has a maximum particle width dimension 110 transverse (perpendicular) to the longitudinal direction 106. The maximum particle width dimension 110 represents the maximum separation distance between opposing surfaces of the fiber-containing particle 100 on a line transverse to the longitudinal direction 106. The fiber-containing particle 100 has an aspect ratio equal to the particle length dimension 108 divided by the maximum particle width dimension 110. As shown in FIG. 1 , the fiber-containing particle 100 has a dual tapered shape having a first tapered portion 112 that tapers in the longitudinal direction 106 from a longitudinal position 114 of the maximum particle width dimension 110 toward the first longitudinal end 102, and a second tapered portion 116 that tapers in the longitudinal direction 106 from the longitudinal position 114 toward the second longitudinal end 104.

[0021] Figure 2 also illustrates a feature of the fiber-containing particle of the present disclosure. As shown in Figure 2, the fiber-containing particle 140 has a first longitudinal end 142, a second longitudinal end 144, a longitudinal direction 146, a particle length dimension 148, a maximum particle width dimension 150 at a longitudinal location 154, a first tapered portion 152, and a second tapered portion 156. Figure 2 illustrates that the first tapered portion 152 tapers over a portion of the particle length dimension in a tapering envelope of a right circular cone 158 having a first opening (cone angle) α having an apex coinciding with the first longitudinal end 142. Similarly, the second tapered portion 156 tapers over a portion of the particle length dimension in a tapered envelope of a right circular cone 162 having a second opening (cone angle) β having an apex coinciding with the second longitudinal end 144. As can be appreciated, with the generally asymmetric shape of the fiber-containing particles resulting from the manufacturing methods of the present disclosure, such a first opening α of the right circular cone envelope of the first tapered portion 152 will typically be different from such a second opening β of the right circular cone envelope of the second tapered portion 156, even if they are relatively similar in value. Also, as shown in FIG. 2, the fiber-containing particle 140 of the present disclosure need not be continuously tapered from the location of the maximum particle width dimension toward each of the first and second longitudinal ends 142, 144 of the fiber-containing particle 140. In that regard, the exemplary fiber-containing particle 140 illustrated in FIG. 2 includes a local minimum width 166 and a local maximum width 168 occurring in the longitudinal direction 146 between the maximum particle width dimension 150 and the second tapered portion 156. As can also be appreciated, neither the first nor the second tapered portion of a fiber-containing particle of the present disclosure need to be completely and continuously tapered to each longitudinal end of the fiber-containing particle. For example, the fiber-containing particle 140 can include a small portion near the first longitudinal end 142 that is not continuously tapered or within the tapered envelope of the right circular cone 158. The fiber-containing particle 140 can include a small portion near the second longitudinal end 144 or that is not continuously tapered or within the tapered envelope of the right circular cone 162.As can be appreciated, small bundles of fiber ends may occur near the first longitudinal end 142 and / or the second longitudinal end 144 that interrupt the tapering of the first tapered portion 152 and / or the second tapered portion 156 near the respective longitudinal ends (142, 144).

[0022] FIG. 3 is a general process block diagram illustrating an exemplary process 200 for producing fiber-containing particles of the present disclosure comprising reinforcing fibers held in the particle structure by a binder. The process 200 comprises rotary tumbling 206 of a mixture of reinforcing fibers and binder material 204 from a fiber feed 202 to form aggregates 208 comprising reinforcing fibers in an aligned configuration in which the reinforcing fibers tend to be generally aligned as they extend along the length of the aggregate. Rotary tumbling 206 may typically be performed in a rotating vessel such as a rotating drum or similar rotatable processing vessel comprising a mixture of reinforcing fibers from the fiber feed 202 and the binder material 204. Each of the fiber feed 202 and the binder material 204 may be introduced into the processing vessel as a single addition or as multiple separate additions, or may be added alone or in a mixture or blend with other materials. As an example, the binder material may be provided in a liquid suspension in which the binder material comprises particulates suspended in a carrier liquid, typically an aqueous liquid. The fibers of the fiber feed 202 may be unsized fibers, such as, for example, carbon or other fibers that are not coated with a sizing. Alternatively, the fibers of the fiber feed 202 may be presized fibers, such as, for example, carbon or other fibers that have a basic fiber structure that has been coated with a thin layer of a sizing material. The sizing is typically a thin polymer coating that provides protection to the underlying base fiber structure (e.g., carbon fiber structure) and / or acts as a compatibilizer to enhance the bonding with and / or dispersibility in the expected matrix material with which the fibers may be combined to prepare a fiber-reinforced composite material. If the fibers are presized fibers before being mixed with the binder material, the sizing is considered to be part of the fibers and part of the fiber content of the fiber-containing particles. If the fibers are presized fibers, the sizing typically accounts for 5 weight percent or less of the fibers, preferably 3 weight percent or less of the fibers, and more preferably 2 weight percent or less of the fibers. Some or all of the fiber feed 202 and the binder material 204 may be introduced into the processing vessel separately from each other or together as a mixture.The fiber feed 202 and / or binder material 204 can be introduced into the process vessel before or during rotation of the process vessel. The rotating vessel may be operated in a batch mode to prepare a batch of aggregates 208 from a corresponding batch of fiber feed and binder material that has been loaded into the vessel for rotation (206) as a batch, and to remove the aggregates as a processed batch at the end of the batch rotation (206) after rotation of the vessel has stopped. Alternatively, the rotating vessel may be operated in a continuous or semi-continuous mode, for example, where the fiber feed 202 and binder material 204 are continuously or semi-continuously introduced into an upstream portion of the rotating vessel and the aggregates 208 are removed from a downstream portion of the rotating vessel.

[0023] Some important variables in the operation of rotary tumbling include the amount of binder material used relative to the length of the fibers being processed, the amount of fibers being processed, the relative amount of liquid (typically water) mixed with the binder material and fibers in the mixture subjected to rotary tumbling, the tangential speed (tip speed) of the inner wall of the rotary vessel during rotary tumbling, and whether the rotary vessel is equipped with internal baffles to promote a more vigorous tumbling action, including tumbling at slow tangential speeds. In general, it has been found that the longer the average fiber length in the fiber feed, the larger the resulting fiber-containing particles. In many situations, the weight average length of the reinforcing fibers in the fiber feed ranges from 1 millimeter to 18 millimeters. The resulting fiber-containing particles may often have a weight average particle length dimension that is about 2 to 3 times the weight average fiber length of the fibers fed to the rotary tumbling. Particularly when producing fiber-containing particles for compounding with polymers in an extruder, the preferred weight average particle length dimension of the fiber-containing particles is often less than about 14 millimeters for processing that is compatible with many conventional compounding systems. Generally, as the proportion of binder material increases, the dispersion of fibers from the fiber-containing particles in the polymer compound may decrease. Thus, at a certain point, the amount of binder becomes too high. That is, it has been found that not only does it not allow for effective disintegration of the fiber-containing particles in the polymer compound, but also that effective dispersion of the reinforcing fibers from the fiber-containing particles is not obtained. As the amount of binder material decreases relative to the amount of fiber in the fiber feed to the rotary tumbling, the particle integrity of the fiber-containing particles during handling may be compromised. Thus, at a certain point, the amount of binder material becomes insufficient to maintain the desired particle integrity during handling operations prior to polymer compounding. Generally, the binder material is typically present in an amount ranging from about 0.5 weight percent to about 11 weight percent relative to the weight of the fiber. Thus, about 0.5 weight percent to about 10 weight percent of binder is provided in the final fiber-containing particles.It has also been found that too much or too little liquid (typically water) content in the treatment mixture during rotary tumbling generally impairs the development of fiber-containing aggregates having the desired size, shape, and particle integrity. Insufficient water will result in the material not bundling well during the agglomeration process, i.e. the fibers will remain largely separate fibers. Excess water will increase the length, width, and volume of the bundles, so that at some point the bundle size will become so large in one or more dimensions that it will not be suitable for practical use in conventional compounding and feeding equipment. Adding water beyond this point will result in a slurry that is not well bundled. In general, the liquid (typically water) content in the treatment mixture will often range from about 10 weight percent to about 50 weight percent based on the total weight of the mixture (the total weight of fiber + binder material + liquid + other minor ingredients). The rotary vessel may be without internal baffles or may include internal baffles to promote a more vigorous tumbling action, especially when operating at slow tangential speeds. Generally, the tangential speed of the inner wall of the rotating vessel during rotary tumbling is often in the range of 0.3 to 1.4 meters per second, while tangential speeds in the range of about 0.6 meters per second to about 0.8 meters per second work well in many test runs of rotating drums that do not include internal baffles. If the rotation speed is too high, the fibers will stick to the drum walls with little or no tumbling mechanism to bundle the fibers. If the rotation speed is too low, the bundles will be produced at a slow or negligible rate. The addition of an internal baffle should allow the rotating vessel to be operated at a slower speed with satisfactory results compared to the same rotating vessel without the internal baffle. When internal baffles are used, the rotating vessel includes at least one, and preferably at least three, internal baffles that project inwardly from the rotating wall of the vessel into the vessel interior. In a preferred embodiment, the internal baffles are equally spaced radially about the axis of rotation of the vessel. The baffles may preferably extend into the vessel from the wall a distance up to 50% of the vessel radius, and preferably extend at least 50 millimeters from the vessel wall.The baffles are preferably oriented so that they extend into the vessel perpendicular to a tangent to the vessel wall and extend longitudinally along the axis of rotation. Alternatively, one or more baffles may be disposed at an angle other than perpendicular to the tangent to the wall and / or disposed longitudinally that does not coincide with the axis of rotation (e.g., helically disposed along the vessel wall). FIG. 4 shows a rotatable processing vessel 180 in the form of a rotating cylindrical drum having a vessel wall 182 and four baffles 184 equally spaced radially about a rotation axis 186 and projecting inwardly from the vessel wall 182 toward the axis of rotation 186. For purposes of illustration, FIG. 4 shows a directional arrow indicating rotation of the processing vessel 180 in a clockwise direction about the axis of rotation 186, although rotation may alternatively be counterclockwise.

[0024] In general, bulk products having fiber-containing particles tend to exhibit better flowability as the untapped bulk density of the bulk product increases, as the tapped bulk density of the bulk product increases, and as the angle of repose of the bulk product decreases. For a particular fiber feed having a weight average fiber length in a range suitable for processing as disclosed herein, suitable processing conditions for preparing agglomerates of fiber-containing particles can be selected and optimized through routine processing trials, adjusting the processing variables noted above, without undue experimentation, to obtain fiber-containing particles having the appropriate size and shape and exhibiting suitable properties for handling in bulk products and fiber breakup and dispersion in polymer blends.

[0025] As shown in Figure 3, the illustrated method may include an optional pre-processing 210 to prepare the fiber feed 202 and / or binder material 204 in a desired form for rotary tumbling 206, and / or an optional subsequent processing 212 to prepare a final fiber-containing particle 214 product from the process 200. As can be appreciated, if the example method of Figure 3 does not include subsequent processing 212, the agglomerates 208 may comprise the final fiber-containing particle 214 of the process of Figure 3. The fiber-containing particle 214 may be recovered as or incorporated into a bulk product.

[0026] FIG. 5 shows a general flow diagram of one example of some processes that may be performed during the optional preliminary processing 210 of FIG. 3. The optional preliminary processing 210 may include either or both of a chopping process 222 and a premixing process 226 performed on a preliminary fiber supply 228 to prepare a fiber supply 202 and / or binder material 204 having a desired morphology and / or desired properties for feeding into the rotary tumbling 206. In the optional chopping process 222, the fibers in a preliminary form are chopped to produce chopped fibers 230 having a shorter average fiber length than the preliminary fiber supply 228. An advantage of the rotary tumbling process of the present disclosure is that it is generally not necessary to remove very short fibers from the process. Such very short fibers may be successfully incorporated into the aggregates 208 and fiber-containing particles 214 along with the longer fibers. The short fibers may contribute beneficially to fiber reinforcement performance, even if not to the same extent as the longer fibers. Retention of very short fibers allows for beneficial use of those fibers in reinforcement applications, thus avoiding waste. If the pre-processing 210 of FIG. 5 includes a pre-mixing process 226, the fiber feed to the pre-mixing process 226 is mixed with a binder material feed 236 that includes some or all of the binder material 204 for rotary tumbling 206 to prepare a pre-mix 238 that includes the fibers and binder material. The fiber feed to the pre-mixing process 226 may be chopped fibers 230 if the pre-processing includes a cutting process 222, or may be a pre-fiber feed 228 if the pre-processing 210 does not include a cutting process 222. If the pre-processing 210 includes a pre-mixing process 226, the binder material feed 236 may include some or all of the binder material 204 for rotary tumbling, and the pre-mix 238 may include some or all of the binder material 204 and fiber feed 202 for rotary tumbling.

[0027] Figure 6 shows a general flow diagram of one example of some processes that may be performed during optional subsequent processing 212 of Figure 3. Optional subsequent processing 212 may include any one, any two, or all three of the optional processing operations of drying 250, curing 252, and classification 254 performed on the agglomerates 208 to prepare fiber-containing particles 214 having desired properties. In optional drying 250, the agglomerates 208 are dried to reduce the residual liquid, typically water, content to a desired low level in the fiber-containing particles 214. During drying 250, the agglomerates 208 are preferably subjected to elevated temperatures and / or reduced pressure to promote evaporation of liquid from the agglomerates 208 to prepare dried agglomerates 256. In situations where the fiber-containing particles 214 are co-extruded with a polymer, there is often a concern for components that have the potential to vaporize at the high temperatures encountered during extrusion. This includes residual moisture that has the potential to vaporize during the extrusion process. Thus, in some preferred embodiments, the moisture content in the dried aggregates 256 and fiber-containing particles 214 is very low, typically less than 0.5 weight percent water, preferably less than 0.3 weight percent water, and more preferably less than 0.2 weight percent water. However, some level of residual water may be present, such as at least 0.001 weight percent water, or at least 0.01 weight percent water. An optional curing process 252 may be included if the binder material requires curing to fully cure and form the final binder composition of the cured particles 258. Curing may be activated by any suitable energy source, such as radiation (light) or heat, depending on the nature of the binder material 204. Thermal curing is generally more preferred in most curing embodiments. A curing process 252 may be included, for example, when the binder material 204 comprises a thermosetting resin (e.g., an epoxy resin) that crosslinks during curing. In some implementations, the binder material comprises a thermoplastic polymer rather than a thermosetting resin. Binder systems that use thermoplastic polymers can often be processed without the need for a curing process 252.However, some binder systems using thermoplastic polymers may benefit from a process comprising an ultra-high temperature curing process 252, for example to improve solubility in aqueous solutions or to remove chemical functional groups from the thermoplastic polymer that may have been added to the polymer to improve wetting of the fibers by the thermoplastic polymer. If the subsequent process 212 of FIG. 6 comprises a drying process 250, the feed to the curing process 252 may be dried particles (256, cured particles) or else the aggregates 208. If the subsequent process 212 comprises both a drying process 250 and a curing process 252, the drying process 250 and the curing process 252 may be performed as separate operations or may be performed in a combined operation, for example, the drying process 250 may be performed first at a lower elevated temperature and then the curing process 252 may be performed in the same processing equipment (e.g., the same oven) at a higher elevated temperature following the drying process 250. In the optional classification process 254, the fiber-containing particle feed is subjected to a size classification to remove oversized particles 260. The oversized particles 260 comprise particles that are larger and / or smaller in one or more dimensions, typically particle length, than the range of such dimensions desired in the fiber-containing particles 214. The resulting classified particles 262 have a narrower distribution of one or more dimensional properties, typically particle length, than the particles in the feed to the classification process 254. In a preferred embodiment, the classification process 254 comprises removing only oversized particles having a dimension, typically particle length, larger than the desired maximum value for that dimension in the fiber-containing particles 214. For example, particles having a length greater than the maximum particle length desired for feeding to the extruder may be removed during the classification process 254. The classification process 254 may include size separation of the fibers by any one or more techniques, including, for example, any one or more of screening, vibration classification, air classification, centrifugal classification, optical sorting, and electrostatic classification.If the subsequent process of FIG. 6 includes a classification process 254, the feed to the classification process 254 may be, for example, the aggregates 208 if the subsequent process 212 does not include the drying process 250 or the hardening process 252, dried particles (256) if the subsequent process 212 includes the drying process 250 but not the hardening process 252, or hardened particles 258 if the subsequent process 212 includes the hardening process 252. Also, if the subsequent process 212 includes both the hardening process 252 and the classification process 254, the process operations may be performed in an order in which the hardening process 252 is performed before the classification process 254, as illustrated in FIG. 6, or in an alternate order in which the classification process 254 is performed before the hardening process 252. One advantage of such an alternate order is that the off-sized fibers (260) in the unhardened aggregates may be easier to process to recover the fibers for further processing than the fibers in the hardened aggregates. Similarly, if the subsequent process 212 includes both a drying process 250 and a classification process 254, the order of operations may be such that the drying process 250 is performed before the classification process 254, as illustrated in Figure 6. Or, in an alternative order, the classification process 254 may be performed before the drying process 250. In that case, the agglomerates 208 may be classified before being dried during the drying process 250. In a preferred process including a drying process 250 and a classification process 254, the drying process 250 is performed before the classification process 254, as illustrated in the sequence shown in Figure 6.

[0028] Reference is now made to Figure 7, which illustrates a generalized flow diagram of an example process for producing a fiber-containing product. The process of Figure 7 comprises process 200 of Figure 3 in which a preliminary supply of fibers 270 is processed to prepare a fiber-containing bulk product 272. The preliminary supply of fibers 270 may be provided in the form of fiber supply 202 of Figure 3, for example, if process 200 does not include preliminary treatment 210. Or the preliminary supply of fibers 270 may be in the form of preliminary fiber supply 228 if process 200 includes preliminary treatment 210. The fiber-containing bulk product 272 is in the form of a batch of fiber-containing particles 214 of process 200 of Figure 3. The batch may comprise aggregates 208, dried particles (256), hardened particles 258, or classified particles 262, depending on whether process 200 includes subsequent processes 212 and in what order one or more of drying 250, curing 252, and classification 254 processes are included in subsequent processes 212. Fiber-containing bulk product 272 may be a mixed product of fiber-containing particles 214, e.g., mixed with other fiber-containing particles with additional fibers, which may be of the same or different composition as the fibers of fiber-containing particles 214, or mixed with one or more other particulate components. For example, fiber-containing bulk product 272 may include a blend of carbon fibers in the fiber-containing particles and additional carbon fibers or additional fibers (not carbon fibers) of different composition in other particles. As shown in FIG. 7, the method optionally includes processes that may be performed before and / or after process 200. The process of FIG. 7 may optionally include a regeneration process 300 for processing a composite supply 302 to prepare a pre-supply of fibers 270, and / or the process of FIG. 7 may optionally include a composite preparation process 400 for preparing a fiber reinforced composite product 402.

[0029] FIG. 8 shows a generalized flow diagram of some exemplary processes that may be performed during an optional composite preparation process 400 to prepare a fiber-reinforced composite product comprising reinforcing fibers from a fiber-containing bulk product 272. In the example of FIG. 8, the composite preparation process 400 may include dispersing 404 the fibers of the fiber-containing bulk product 272 into a matrix to form a fiber-reinforced composite 406. The matrix material may be provided in a matrix material supply 408. Additional components 410 may also be provided to the dispersion process 404 for inclusion in the fiber-reinforced composite 406. Such additional components 410 may comprise additives such as functional or non-functional fillers and / or processing aids. The additional components 410 may include additional reinforcing fibers in addition to the reinforcing fibers from the fiber-containing bulk product 272. The additional reinforcing fibers may be of the same type as the fibers in the fiber-containing bulk product 272 or may be of a different type. In some preferred process embodiments, the dispersion process 404 includes extruding a polymeric material of the matrix material feed 408 and adding fiber-containing particles of the fiber-containing bulk product 272 to the polymeric material during extrusion, in which case the fiber-reinforced composite material 406 may be in the form of an extrudate.

[0030] 8, the optional composite preparation process 400 can also include a cooling process 420 during which the fiber reinforced composite material 406 is cooled, for example, by passing the fiber reinforced composite material 406 through a bath of cooling liquid (e.g., water). This process may be desirable when the composite material prepared during the dispersion process 404 is at an elevated temperature, such as in the case of extrusion. The cooled composite material 422 from the cooling process 420 can be subjected to a pelletizing process 426 to prepare pellets 428 of the fiber reinforced composite material. The pelletizing process 426 can include, for example, cutting the extruded strands of a desired diameter into cylindrical pellets of a desired length. After the pelletizing process 426, the pellets 428 are subjected to a blending process 430 during which the pellets 428 may be mixed with one or more other particulate components 432 different from the pellets 428 to form a blended bulk product 434. The optional process may also include a molding process 440 in which the fiber reinforced composite feed is molded, preferably by injection molding, to prepare a molded article 442. The fiber reinforced composite feed to the molding process 440 may be, for example, the pellets 428 if the composite material preparation process 400 does not include the blending process 430, or the blended bulk product 434 if the composite material preparation process 400 includes the blending process 430. As can be appreciated, once the pellets 428 or the blended bulk product 434 are sold as a bulk product, the buyer may use the pellets 428 or the blended bulk product 434 for carrying out the molding process 440 or for another purpose.

[0031] With continued reference to the process depicted in FIG. 7, the preliminary supply of fibers 270 may comprise virgin fibers and / or recycled fibers. In a preferred embodiment of the process of FIG. 7, the preliminary supply of fibers 270 comprises recycled fibers (e.g., recycled carbon fibers). Such recycled fibers may be obtained from any source for feeding to the process 200 and optionally prepared through the performance of an optional recycling process 300 to recover recycled fibers from a composite feed 302. The composite feed 302 to the optional recycling process 300 may comprise scrap and / or waste fiber reinforcement materials that are processed in the recycling process 300 to free the recycled fibers from the matrix of the composite feed 302, as well as recovering recycled reinforcement fibers for use in the preliminary supply of fibers 270 to prepare the fiber-containing bulk product 272. The composite feed 302 may comprise a matrix of a thermosetting or thermoplastic polymer composition. The thermosetting matrix may comprise an uncured thermosetting resin (e.g., prepreg) or a cured thermosetting polymer composition. The regeneration process 300 may include any processing technique for separating the reinforcing fibers from the matrix of the composite feed 302. Some exemplary processing techniques include pyrolysis, solvation, or depolymerization of the matrix to release the fibers for recovery. Some preferred embodiments of the regeneration process 300 include the processes disclosed in any of U.S. Patent Nos. 5,399,623, 5,433,292, 5,541,293, and 5,663,133. In some such preferred embodiments of the regeneration process 300, the composite feed 302 is subjected to a first treatment with a first typically liquid solvent to dissolve the matrix material and loose fibers for recovery, then the first solvent loaded with dissolved matrix material is separated from the loose fibers, and then the loose fibers are subjected to a second treatment with a second solvent, typically a gaseous material such as carbon dioxide, to remove the remaining portion of the first solvent. FIG. 9 shows a general flow diagram of one example of such a process that may be performed during any regeneration process 300 for treating a composite material supply 302 to prepare a pre-supply of fiber 270 comprising recycled fibers for feeding into process 200.As seen in Figure 9, the composite feed 302 is subjected to a first treatment 304 during which the composite feed 302 is contacted with a first solvent 306, preferably a typically liquid solvent, to dissolve most or essentially all of the matrix material from the composite feed 302, thereby leaving the reinforcing fibers free from the composite structure. The resulting mixture 308 comprising the first solvent loaded with the dissolved matrix material and the free reinforcing fibers is then subjected to a liquid-solid separation 310 during which most of the loaded first solvent, preferably all but a small residual amount, is recovered in a separation liquid 312. Most of the free fibers, preferably essentially all, are recovered in a solid residue 314, which also comprises a residual amount of the first solvent. The solid residue 314 is then subjected to a second treatment 316 during which the solid residue 314 is contacted with a second solvent 318, which is a solvent for the first solvent and is not a solvent for the reinforcing fibers. A loaded second solvent 320 comprising the dissolved residual portion of the first solvent and a dry solid residue 322 comprising the loose reinforcing fibers from which the residual portion of the first solvent has been removed are recovered from the second process 316. The dry solid residue 322 may be used directly as recovered from the second process 316 as a pre-supply of fibers 270 to process 200 or may be further processed as desired to prepare a pre-supply of fibers 270.

[0032] As used herein, the term "bulk product" refers to a particulate product, e.g., in the form of a powder, lump, or granule, with intra- and inter-particle voids. This term can be used interchangeably with the term "bulk material."

[0033] As used herein, the term "bulk density" refers to the apparent density of a quantity of bulk product. Bulk density can be determined by dividing the mass of the quantity of bulk product by the volume occupied by that quantity of bulk product, including intra- and inter-particle voids.

[0034] As used herein, the terms "untapped bulk density" and "free settling bulk density" are used interchangeably and refer to the bulk density of a bulk product that has been measured according to a procedure similar to, but modified from, ASTM standard D7481-18, as follows:

[0035] Measure and record the weight to the nearest gram of a clean, empty 0.5 L straight walled beaker, such as a Cole Parmer graduated Griffin Beaker #SK-34502-46, or equivalent container.

[0036] Fill the graduated beaker to the top mark by gently sieving the bulk product particles from the container into the beaker, ensuring a neutral fill. A funnel may be used if necessary.

[0037] The weight of the filled beaker is measured in grams to determine the weight of the particles in the beaker by weight difference relative to the empty beaker to an accuracy of at least 0.1 grams. The weight difference may be determined directly by zeroing the balance to the tare weight of the empty beaker before adding the bulk product, or the combined weight of the beaker and bulk product may be determined and then the weight of the particles in the filled beaker by weight difference relative to the empty beaker.

[0038] Bulk density (grams / liter) is equal to twice the determined weight of the particles in the filled beaker. As used herein, the term "tapped bulk density" refers to the bulk density of a bulk product measured according to a procedure similar to ASTM standard D7481-18, but which is a modification of ASTM standard D7481-18.

[0039] First, the bulk density measurement procedure described above is carried out. The filled beaker is then transferred to a hard surface such as a table or counter and the beaker is then repeatedly raised 1-2 cm above the surface and dropped back onto the surface, striking the bottom of the beaker against the surface approximately 90 times per minute.

[0040] Tapping is continued until the settled volume of bulk product in the beaker remains fairly constant (within about 2%) for at least 10 taps. Measure the settled volume of the bulk product in the beaker to the nearest 5 milliliters.

[0041] The tapped bulk density (grams / liter) is determined by dividing the weight of the bulk product (grams), determined during pre-processing to determine the untapped bulk density, by the measured settled volume of the bulk product (liters).

[0042] As used herein, the "angle of repose" of a bulk product refers to the angle of repose of a stacked pile of bulk product as determined by the following procedure, which is similar to, but modified from, ASTM Standard C1444-00.

[0043] Obtain a funnel large enough to hold a 150 g sample of the bulk product with a funnel outlet diameter of 2.75 in. (6.9 cm). For example, the funnel may be a standard 48 oz. (1.36 kg) plastic long neck funnel, model #LX-1614, sold at Home Depot or equivalent. It may be necessary to trim the funnel to obtain the appropriate outlet size.

[0044] Pour 150 g of bulk product into the funnel while covering the outlet of the funnel with a flat surface such as a flat piece of cardboard. While holding the funnel outlet at a height of 4.5 inches (11.4 cm) above a clean paper (such as printer paper), remove the cover from the funnel outlet and allow the bulk product to flow out of the funnel outlet, forming a pile on top of the paper. Place the funnel on a stand that will not interfere with the formation of a pile. A cylindrical cardboard stand 10 inches (25.4 centimeters) in diameter is generally suitable for the bulk product of fiber-containing particles of the present disclosure.

[0045] After the flow of bulk product from the funnel has stopped, thereby preventing the pile of bulk product from settling, measure and record two vertical diameters at the bottom of the stack. Measure the height of the stack to the nearest 0.25 inch (6.4 mm) each and average the measured diameters.

[0046] The angle of repose is calculated as follows: AR=tan-1(2h / d). Here, AR is the angle of repose, h is the height of the pile, and d is the average diameter of the base of the pile.

[0047] [Example] Example 1 A batch of fiber-containing particles is generally prepared according to the following procedure.

[0048] 1. A supply of recycled carbon fiber previously recovered from prepreg composites is chopped using a guillotine chopper set to a cut setting of 3 mm, 6 mm, or 12 mm. As will be appreciated, the chopped fibers may be longer or smaller than the cut setting based on how long the original fibers were before they were chopped by the guillotine blade and what angle the fibers were positioned relative to the blade when chopped. The fibers are passed through the chopper 3-4 times to make the cut length of the fibers more uniform.

[0049] 2. Finally, 10 to 30 kilograms of chopped fiber was poured into a 55 gallon drum and water and binder material were added to form a chopped fiber mixture. The mixture had 20 to 35 weight percent water and 1 to 5 weight percent binder material. The remainder was chopped fiber. Examples of binders tested are shown in Table 1. The water and binder material were premixed and the water and binder material mixture was poured onto the fiber in the 55 gallon drum. In general, chopped fiber prepared at 3 millimeter increments had a higher weight percent water added. Chopped fiber prepared at 6 or 12 millimeter increments had a lower weight percent water added. After the water and binder mixture was added, the drum was closed.

[0050] 3. The closed drum was placed on the drum roller, and the rotation speed of the drum roller was set to 24 revolutions per minute (the tangential speed of the cylindrical inner wall of the drum was about 0.7 m per second). The drum containing the contents was rolled for a total of about 120 to 210 minutes. The rotation of the drum was interrupted for a short time about every 30 minutes to check the progress of agglomeration and to scrape off excess fibers from the drum wall.

[0051] 4. The agglomerates obtained by drum rolling in step 3 were removed from the drum and classified using a vibrating screen classifier equipped with a screen having a screen opening of 1 / 4 inch (6.35 mm), 3 / 8 inch (9.53 mm), or 1 / 2 inch (12.7 mm). Oversized particles that did not pass through the screen were removed.

[0052] 5. The classified agglomerates were dried in an oven at 300°F (149°C) for 8 to 12 hours so that essentially all of the water had been removed. Figure 10 is a photographic image of an example of recycled carbon fiber before chopping. As can be seen in Figure 10, the recycled carbon fiber has a cotton ball-like structure with a large degree of randomness in the orientation of the carbon fibers.

[0053] [Table 1]

[0054] FIG. 11 is a photographic image of two example batches of fiber-containing particles made from recycled carbon fiber. The fiber-containing particles of each batch are dispersed on a white paper background to enhance the visibility of the individual particles of each batch. One example batch, shown at the top of the image, was prepared by operating the chopper at a 6 mm setting, so that the average particle length of the resulting fiber-containing particles is approximately 12 mm. The other example batch, shown at the bottom of the image, was prepared by operating the chopper at a 3 mm setting, so that the average particle length of the resulting fiber-containing particles is approximately 8 mm. In each batch, the elongated shape of the particles and the general alignment of the fibers with the length of the particles can be seen. Many of the particles also have a well-developed dual tapered shape.

[0055] FIG. 12 is a photographic image of a bulk product in a beaker prepared using particles from a batch of fiber-containing particles made from a feed of recycled carbon fibers chopped using a 6 mm chopper setting. FIG. 13 is a photographic image looking down on such a bulk product. The bulk product was tested for bulk density and angle of repose according to the methods described herein. The bulk product had an unadjusted bulk density of about 200 grams per cubic liter, an adjusted bulk density of about 300 grams per cubic liter, and an angle of repose of about 36°. These properties indicate good flowability of the bulk product suitable for feeding into an extruder for compounding with a polymer.

[0056] FIG. 14 is a photographic image of a single particle from a batch of fiber-containing particles produced from a feed of recycled carbon fiber that had been chopped at a chopper setting of 6 mm. The particle is approximately 12 millimeters in length and has a well-developed dual tapered particle shape. The fibers are highly aligned along the length of the particle. As can be seen in FIG. 14, the exemplary fiber-containing particle has essentially no fibers protruding from the particle perpendicular to the length of the particle, which helps promote good flowability of such particles in the bulk product.

[0057] Figure 15 is a photographic image showing the inside of a 55 gallon (208 liter, 0.208 cubic meter) rotating drum in which agglomerates made from chopped recycled carbon fiber have been formed using a 6 millimeter chopper setting. The drum is fitted with a clear end cap to allow viewing of the contents within the rotating drum during rotary tumbling.

[0058] Example 2 Extrusion tests were performed on batches of fiber-containing particles with recycled carbon fibers prepared as described in Example 1 to prepare carbon fiber reinforced composites. Table 2 summarizes several polymers that were tested for composite with the prepared fiber-containing particles at different chopper settings. Each polymer was extruded on a twin screw extruder. Some samples were extruded on a Leistritz 27 mm twin screw extruder, while other samples were extruded on other extruders. Batches of fiber-containing particles were prepared using chopper settings of 12 millimeters, 6 millimeters, or 3 millimeters. The fiber-containing particles were fed to the extruder from a conventional bulk handling system to achieve various levels of recycled percent carbon fiber loading in the extrudate, as summarized in Table 2. The Leistritz extruder was fed from a K-Tron_T20 vibratory weight loss feeder. The extrudate was passed through a circular die (e.g., a 2-hole circular die) and the resulting extrudate strands were chopped into cylindrical pellets. The particles were generally well fed into the extruder from the feed hopper during extrusion. Carbon fibers were generally well dispersed in the polymer melt from the fiber-containing particles. Some of the test pellets were used as feed for injection molding to produce molded test coupons of carbon fiber reinforced materials from the pellets. Some of the extruded pellets with polyamide polymer were injection molded to produce ISO 527-2 Type 1A tensile bars and ISO 197-2 Type D impact specimens. The molded materials showed comparable tensile strength, modulus, impact strength, and other properties compared to the manufacturer's specifications of a 40% carbon fiber reinforced commercial compound material with the same baseline polyamide polymer and virgin carbon fiber. The molding of the test specimens was facilitated by suitable high pressure injection and heated mold. Some of the molded specimens were subjected to XCT (X-ray computed tomography) examination, which confirmed similar void and fiber distribution between the test specimens and the corresponding baseline commercial compound material with virgin carbon fiber.

[0059] [Table 2]

[0060] Combination of Exemplary Embodiments Some other contemplated embodiments of combinations of various aspects of the present disclosure, with or without additional features as disclosed above or elsewhere in this specification, are summarized in the following numbered paragraphs and the appended claims.

[0061] <Appendix 1> 1. A fiber-containing particle having reinforcing fibers bonded within the particle structure, optionally said fiber-containing particle being useful for blending said reinforcing fibers with a polymer, said fiber-containing particle comprising: 90 weight percent to 99.5 weight percent of the reinforcing fibers; 0.5 weight percent to 10 weight percent of a binder that holds the reinforcing fibers within the particle structure; a particle length dimension in the range of 3 millimeters to 40 millimeters, the maximum longitudinal separation distance between a first longitudinal end and a second longitudinal end of the fiber-containing particle; a maximum particle width dimension transverse to the longitudinal direction at a longitudinal position between the first longitudinal end and the second longitudinal end; an aspect ratio of at least 1.5, which is equal to the length dimension of the fiber-containing particle divided by the maximum width dimension of the fiber-containing particle; a dual tapered shape having a first tapered portion tapering in the longitudinal direction away from the longitudinal position toward the first longitudinal end and a second tapered portion tapering in the longitudinal direction away from the longitudinal position toward the second longitudinal end, and optionally the fiber-containing particles may contain small amounts of materials other than the reinforcing fibers and the binder, such as small amounts (typically 0.5 weight percent or less, preferably even less) of residual water and / or small amounts of processing additives.

[0062] <Appendix 2> the amount of said reinforcing fibers being in a range having a lower limit selected from the group consisting of 91 weight percent, 92 weight percent, and 93 weight percent, and an upper limit selected from the group consisting of 99 weight percent, 98 weight percent, and 97 weight percent. 2. The fiber-containing particle of claim 1.

[0063] <Appendix 3> a range of amounts of the binder having a lower limit selected from the group consisting of 1 weight percent, 2 weight percent, 2.5 weight percent, and 3 weight percent, and an upper limit selected from the group consisting of 9 weight percent, 7 weight percent, 6 weight percent, and 5 weight percent; The fiber-containing particle of any one of claims 1 or 2. One preferred range is from 2 weight percent to 6 weight percent of the binder, and another preferred range is from 2.5 weight percent to 5 weight percent of the binder.

[0064] <Appendix 4> the reinforcing fibers are in an aligned configuration in which at least 70 weight percent of the reinforcing fibers, preferentially at least 80 weight percent, even more preferentially at least 85 weight percent, extend in the longitudinal direction within an angle of 20° to the longitudinal direction, preferentially within an angle of 10° to the longitudinal direction; 4. A fiber-containing particle according to any one of claims 1 to 3.

[0065] <Appendix 5> the particle length dimension is within a range having a lower limit selected from the group consisting of 3.5 millimeters, 4 millimeters, 5 millimeters, and 6 millimeters; 5. A fiber-containing particle according to any one of claims 1 to 4.

[0066] <Appendix 6> the particle length dimension is within a range having an upper limit selected from the group consisting of 30 millimeters, 20 millimeters, 16 millimeters, and 14 millimeters; A fiber-containing particle according to any one of claims 1 to 5. One preferred range for the particle length dimension is from 5 millimeters to 16 millimeters, and an even more preferred range is from 6 millimeters to 14 millimeters.

[0067] <Appendix 7> the aspect ratio is within a range having a lower limit selected from the group consisting of 1.7, 1.8, and 1.9; 7. A fiber-containing particle according to any one of claims 1 to 6.

[0068] <Appendix 8> the aspect ratio is within a range having an upper limit selected from the group consisting of 6, 4, and 3; The fiber-containing particle according to any one of appendixes 1 to 7. A preferred range of the aspect ratio is 1.8 to 4.

[0069] <Appendix 9> said first and second tapered portions each have an apex at each longitudinal end and are tapered over a longitudinal distance of at least 20 percent (preferentially at least 25 percent) of their longitudinal length within a tapered envelope of a right circular cone having an opening of not more than 45°, preferentially not more than 40°, even more preferentially not more than 37°, even more preferentially not more than 35°, and preferentially in each case said opening is at least 10°; A fiber-containing particle according to any one of claims 1 to 8.

[0070] <Appendix 10> the binder comprises a material selected from the group consisting of polyether polyurethane (preferably cured), polyester polyurethane (preferably cured), maleated polypropylene, polyaryletherketone (PAEK), and epoxy polymer (preferably cured); 10. A fiber-containing particle according to any one of claims 1 to 9.

[0071] <Appendix 11> the maximum particle width dimension is within a range having a lower limit selected from the group consisting of 1 millimeter, 2 millimeters, 3 millimeters, and 4 millimeters, and an upper limit selected from the group consisting of 10 millimeters, 8 millimeters, 6 millimeters, and 5 millimeters; 11. A fiber-containing particle according to any one of claims 1 to 10.

[0072] <Appendix 12> having 0.5 weight percent or less of water, preferably 0.3 weight percent or less of water, and more preferably 0.2 weight percent or less of water; 12. A fiber-containing particle according to any one of claims 1 to 11.

[0073] <Appendix 13> 1. A bulk product comprising reinforcing fibers, the bulk product comprising a plurality of fiber-containing particles, the plurality of fiber-containing particles comprising: 90 weight percent to 99.5 weight percent of the reinforcing fibers; and 0.5 weight percent to 10 weight percent of a binder that holds the reinforcing fibers within a particle structure of the fiber-containing particles, Each of the fiber-containing particles comprises: a particle length dimension in the range of 3 millimeters to 40 millimeters, the maximum longitudinal separation distance between a first longitudinal end and a second longitudinal end of the fiber-containing particle; a maximum particle width dimension transverse to the longitudinal direction at a longitudinal position between the first longitudinal end and the second longitudinal end; an aspect ratio equal to said particle length dimension divided by said maximum particle width dimension of at least 1.5; a dual taper comprising a first tapered portion tapering in the longitudinal direction away from the longitudinal location toward the first longitudinal end and a second tapered portion tapering in the longitudinal direction away from the longitudinal location toward the second longitudinal end; Preferably, the plurality of fiber-containing particles comprises: A plurality of the fiber-containing particles according to any one of claims 1 to 12, Optionally, the bulk product comprises at least 25 weight percent of the fiber-containing particles, or more than 50 weight percent of the fiber-containing particles, or at least 75 weight percent of the fiber-containing particles, or at least 90 weight percent of the fiber-containing particles, and optionally, the bulk product comprises a portion of particles other than the fiber-containing particles, further optionally at least 10 weight percent. Bulk products.

[0074] <Appendix 14> the bulk product having a weight average particle length dimension of the fiber-containing particles in the range of 3 millimeters to 40 millimeters, the weight average particle length dimension being an average, by weight, of the particle length dimensions of the fiber-containing particles; the fiber-containing particles have a weight average aspect ratio of at least 1.5, the weight average aspect ratio being the average, by weight, of the aspect ratios of the fiber-containing particles; Bulk products as described in Appendix 13.

[0075] <Appendix 15> 1. A bulk product comprising a plurality of fiber-containing particles, the plurality of fiber-containing particles comprising: 90 weight percent to 99.5 weight percent reinforcing fibers; and 0.5 weight percent to 10 weight percent of a binder that holds the reinforcing fibers in a particulate structure; Each of the fiber-containing particles comprises: a particle length dimension, the maximum longitudinal separation distance between a first longitudinal end and a second longitudinal end of the fiber-containing particle; a maximum particle width dimension transverse to the longitudinal direction at a longitudinal position between the first longitudinal end and the second longitudinal end; an aspect ratio equal to said particle length dimension divided by said maximum particle width dimension; a dual taper comprising a first tapered portion tapering in the longitudinal direction away from the longitudinal location toward the first longitudinal end and a second tapered portion tapering in the longitudinal direction away from the longitudinal location toward the second longitudinal end; In the plurality of fiber-containing particles, the fiber-containing particles have a weight-average particle length dimension in the range of 3 mm to 40 mm, the weight-average particle length dimension being an average of the particle length dimensions of the fiber-containing particles on a weight basis; the fiber-containing particles have a weight average aspect ratio of at least 1.5, the weight average aspect ratio being the average, by weight, of the aspect ratios of the fiber-containing particles; Optionally, the bulk product comprises at least 25 weight percent of the fiber-containing particles, or more than 50 weight percent of the fiber-containing particles, or at least 75 weight percent of the fiber-containing particles, or at least 90 weight percent of the fiber-containing particles, and optionally, the bulk product comprises a portion of particles other than the fiber-containing particles, further optionally at least 10 weight percent. Bulk products.

[0076] <Appendix 16> the weight average particle length dimension is within a range having a lower limit selected from the group consisting of 3.5 millimeters, 4 millimeters, 5 millimeters, and 6 millimeters; 16. The bulk product of any one of claims 14 or 15.

[0077] <Appendix 17> the weight average particle length dimension is within a range having an upper limit selected from the group consisting of 30 millimeters, 20 millimeters, 16 millimeters, and 14 millimeters; 17. The bulk product of any one of claims 14 to 16. One preferred range for the weight average particle length dimension is from 5 millimeters to 16 millimeters, and an even more preferred range is from 6 millimeters to 14 millimeters.

[0078] <Appendix 18> The particle length dimension of at least 75 weight percent, preferably at least 80 weight percent, more preferably at least 85 weight percent, and even more preferably at least 90 weight percent of the fiber-containing particles is within a range having a lower limit of 0.5, preferably 0.7, times the weight average particle length dimension, and an upper limit of 2, preferably 1.8, times the weight average particle length dimension. 18. The bulk product according to any one of claims 14 to 17.

[0079] <Appendix 19> At least 2 weight percent, or even at least 5 weight percent, or even at least 10 weight percent of the fiber-containing particles have a particle length dimension outside the range of 0.8 times the weight average particle length dimension to 1.2 times the weight average particle length dimension. 19. The bulk product according to any one of claims 14 to 18.

[0080] <Appendix 20> The particle length dimension of at least 98 weight percent of the fiber-containing particles is less than or equal to 3 times the weight average particle length dimension. 20. The bulk product according to any one of claims 14 to 19.

[0081] <Appendix 21> the weight average aspect ratio is within a range having a lower limit selected from the group consisting of 1.7, 1.8, and 1.9; A bulk product according to any one of appendix 14 to 20.

[0082] <Appendix 22> the weight average aspect ratio is within a range having an upper limit selected from the group consisting of 6, 4, and 3; The bulk product according to any one of appendixes 14 to 21. A preferred range of the weight average aspect ratio is 1.8 to 4.

[0083] <Appendix 23> The aspect ratio of at least 75 weight percent of the fiber-containing particles, preferably at least 80 weight percent, more preferably at least 85 weight percent, and even more preferably at least 90 weight percent, is within a range having a lower limit of 1.5 and an upper limit of 4. 23. The bulk product according to any one of claims 14 to 22.

[0084] <Appendix 24> At least 2 weight percent, or even at least 5 weight percent, of the fiber-containing particles have an aspect ratio outside the range of 0.8 to 1.2 times the weight average aspect ratio. 24. The bulk product according to any one of claims 14 to 23.

[0085] <Appendix 25> 25. The bulk product of any one of claims 15 to 24, wherein each of the plurality of fiber-containing particles has any feature as described in any one of claims 1 to 12 or as described in any one of claims 1 to 12.

[0086] <Appendix 26> 1. A method for making a fiber reinforced composite, the method comprising: dispersing reinforcing fibers from the fiber-containing particles of the bulk product according to any one of claims 13 to 25 in a matrix, preferably a polymer matrix, optionally wherein the resulting composite material comprises 5 weight percent to 50 weight percent of the reinforcing fibers, one preferred range being 10 weight percent to 40 weight percent of the reinforcing fibers; A method for providing the same.

[0087] <Appendix 27> The matrix is ​​a polymer matrix comprising a thermoplastic polymer. 27. The method according to claim 26.

[0088] <Appendix 28> The thermoplastic polymer comprises a member selected from the group consisting of polyamide, polypropylene, polyethylene, polyethylene terephthalate, polylactic acid, polycarbonate, acrylonitrile butadiene styrene, polystyrene, and polyaryletherketone. 28. The method according to claim 27.

[0089] <Appendix 29> The step of dispersing comprises extruding a polymeric material for the matrix and adding the fiber-containing particles of the bulk product to the polymeric material during extrusion. 29. The method of any one of claims 27 or 28.

[0090] <Appendix 30> The method further comprises pelletizing the extrudate from the extrusion; the extrudate comprising reinforcing fibers dispersed in a matrix, preparing pellets comprising the reinforcing fibers dispersed in a matrix, optionally the pellets having a maximum cross-sectional dimension (e.g., length dimension) in the range of 1 millimeter to 25 millimeters, preferably 4 millimeters to 18 millimeters, and further optionally the pellets having a width dimension transverse to the maximum cross-section in the range of 1 millimeter to 6 millimeters, preferably 2 to 4 millimeters, preferably the pellets being cylindrical in shape and having a cylindrical length and cylindrical diameter within ranges, preferably preferred ranges, for the maximum cross-sectional dimension and width dimension, respectively; 29. The method according to claim 29.

[0091] <Appendix 31> The method further comprises cooling the extrudate prior to the pelletizing process. 31. The method according to claim 30.

[0092] <Appendix 32> The method further comprises mixing the pellets with at least one other particulate component different from the pellets; Optionally, such another particular component comprises a second pellet of a different composition; Further optionally, such second pellet comprises second reinforcing fibers, which may be the same or different from the reinforcing fibers of the pellet, dispersed in a second matrix, preferably a second polymer matrix, which may be the same or different from the matrix of the pellet; Such second reinforcing fibers are optionally of uniform fiber length cut from a continuous fiber. 32. The method of any one of appendix 30 or 31.

[0093] <Appendix 33> The method further comprises forming the pelletized material into a product form. 33. The method according to any one of appendix 30 to 32.

[0094] <Appendix 34> said molding step comprising injection molding; 34. The method according to claim 33.

[0095] <Appendix 35> the bulk product has a free-settled (untapped) bulk density in a range having a lower limit selected from the group consisting of 100, 200, or 250 grams / liter and an upper limit selected from the group consisting of 400 grams / liter and 350 grams / liter; 35. The bulk product or process of any one of paragraphs 13 to 34. One preferred range of untapped bulk density is in the range of 200 to 300 grams per liter.

[0096] <Appendix 36> 36. The bulk product or method of any one of claims 13 to 35, wherein the bulk product has a tapped bulk density in a range having a lower limit selected from the group consisting of 200, 250, and 300 grams per liter and an upper limit selected from the group consisting of 650 or 600 grams per liter, and optionally the tapped bulk density is in the range of 1.2 to 2 times the untapped bulk density. One preferred range of tapped bulk density is in the range of 250 to 400 grams per liter.

[0097] <Appendix 37> The bulk product comprises at least 50 weight percent, preferably at least 70 weight percent, more preferably at least 90 weight percent, even more preferably at least 95 weight percent, and even more preferably at least 98 weight percent of the fiber-containing particles. 37. The bulk product or method of any one of claims 13 to 36.

[0098] <Appendix 38> The bulk product has a pose angle within a range having a lower limit of 25° and an upper limit of 45°, with one more preferred range of pose angles being within the range of 30° to 40°. 38. The bulk product or method of any one of claims 13 to 37.

[0099] <Appendix 39> the reinforcing fibers in each of the fiber-containing particles have a weight average fiber length less than the particle length dimension, preferably no more than 75 percent of the particle length dimension, and often no more than 60 percent of the particle length dimension; 39. The particle, bulk product, or method of any one of claims 1 to 38.

[0100] <Appendix 40> The weight average fiber length is at least 20 percent of the particle length dimension, preferably at least 25 percent, and often at least 30 percent. 40. The particle, bulk product, or method of claim 39.

[0101] <Appendix 41> the weight average fiber length is at least as great as an amount selected from the group consisting of 1 millimeter, 2 millimeters, 3 millimeters, and 4 millimeters; 41. The particle, bulk product, or method of any one of claims 39 or 40.

[0102] <Appendix 42> the weight average fiber length is less than or equal to an amount selected from the group consisting of 18 millimeters, 12 millimeters, 8 millimeters, and 6 millimeters; 42. The particle, bulk product, or method of any one of claims 39 to 41. One preferred range for the weight average fiber length is from 3 millimeters to 8 millimeters, and another preferred range is from 4 millimeters to 6 millimeters.

[0103] <Appendix 43> At least 70 weight percent, preferably at least 75 weight percent, more preferably at least 80 weight percent, and even more preferably at least 85 weight percent of the reinforcing fibers in the fiber-containing particles have a fiber length in the range of 0.5 to 2 times the weight average fiber length. 43. The particle, bulk product, or method of any one of claims 39 to 42.

[0104] <Appendix 44> At least 10 weight percent of the reinforcing fibers have a fiber length outside the range of 0.7 to 1.5 times the weight average fiber length. 44. The particle, bulk product, or method of any one of claims 39 to 43.

[0105] <Appendix 45> At least 5 weight percent of the reinforcing fibers have a fiber length outside the range of 0.5 to 2 times the weight average fiber length. 45. The particle, bulk product, or method of any one of claims 39 to 44.

[0106] <Appendix 46> At least 15 weight percent of the reinforcing fibers have a fiber length outside the range of 0.8 to 1.3 times the weight average fiber length. 46. ​​The particle, bulk product, or method of any one of claims 39 to 45.

[0107] <Appendix 47> The reinforcing fibers have a weight average aspect ratio of fiber length to fiber width of at least 100, preferably at least 500, more preferably at least 1000. 47. The particle, bulk product, or method of any one of claims 1 to 46.

[0108] <Appendix 48> The reinforcing fibers have a weight average aspect ratio of fiber length to fiber width of 10,000 or less. 48. The particle, bulk product, or method of any one of claims 1 to 47.

[0109] <Appendix 49> 1. A method of making fiber-containing particles having reinforcing fibers held within a particle structure by a binder, the method comprising: processing a fiber supply and a binder material to prepare the fiber-containing particles comprising the reinforcing fibers from the fiber supply, the fiber supply comprising the reinforcing fibers in a non-continuous form; said step of treating said fiber supply and said binder material comprises tumble tumbling a mixture of said reinforcing fibers and said binder material to form agglomerates, each agglomerate comprising a portion of said reinforcing fibers and a portion of said binder material. method.

[0110] Optionally, the method is for making a bulk product comprising said fiber-containing particles, preferably for preparing the bulk product according to any one of claims 13 to 48. method.

[0111] <Appendix 50> Processing the mixture includes placing the reinforcing fibers and the binder material in a processing vessel (e.g., a rotating drum); The rotary tumbling comprises rotating a treatment vessel containing the reinforcing fibers and the binder material. 49. The method according to claim 49.

[0112] <Appendix 51> The rotary tumbling includes rotating the treatment vessel at a tangential velocity (tip speed) on the inner surface of the rotating wall of the treatment vessel in the range of 0.3 to 1.4 meters per second. 51. The method according to claim 50.

[0113] <Appendix 52> The rotary tumbling is carried out for a period ranging from 15 minutes to 240 minutes. The method according to any one of appendices 49 to 51. A more preferred range of the period is 120 minutes to 150 minutes.

[0114] <Appendix 53> the supply of binder material to the process comprises a binder precursor composition comprising the binder material dispersed in a carrier liquid; 53. The method according to any one of appendix 49 to 52.

[0115] <Appendix 54> The binder precursor composition comprises at least a portion of the binder material in a solid state dispersed in a carrier liquid. 54. The method according to claim 53.

[0116] <Addendum 55> the processing comprising combining all or a portion of the binder precursor composition with the reinforcing fibers prior to rotary tumbling (e.g., premixing the binder material and the reinforcing fibers prior to introduction into a processing vessel); 55. The method of any one of claims 53 or 54.

[0117] <Appendix 56> The process includes introducing some or all of the binder precursor composition into a process vessel (e.g., a rotating drum); Optionally, after the reinforcing fibers have been introduced into the treatment vessel, and while the treatment vessel is rotating, the binder precursor composition is sprayed into the treatment vessel to contact and mix with the reinforcing fibers. 56. The method according to any one of appendix 53 to 55.

[0118] <Appendix 57> the treating step comprises evaporating at least a portion of the carrier liquid after contacting the binder precursor composition with the reinforcing fibers, and optionally during and / or after rotary tumbling, preferably at least a portion, and more preferably a majority, of the evaporation occurs after the rotary tumbling; 57. The method according to any one of appendix 53 to 56.

[0119] <Appendix 58> The evaporating step comprises heating the reinforcing fibers and carrier liquid, optionally to a temperature of at least 100° C., and further optionally within the range of 100° C. to 200° C. (not including a post-drying heat cure that may be used as a thermosetting binder composition or a very high temperature thermoplastic binder composition); 58. The method of any one of clauses 57, wherein the method comprises the step of curing the binder material, the dried aggregate is subjected to a higher temperature for curing than that used to dry the aggregate, e.g., the curing temperature may be greater than 200°C, often in the range of 200°C to 380°C. As mentioned above, drying and curing may be performed in a single operation (e.g., in a single oven), with drying occurring during a first stage of heating in a lower elevated temperature range to remove water by evaporation, and curing following a second stage of heating in a higher elevated temperature range for curing.

[0120] <Appendix 59> The carrier liquid is an aqueous liquid; 59. The method according to any one of appendix 53 to 58.

[0121] <Appendix 60> the treating step comprising combining the binder material, the reinforcing fibers, and water prior to completion of the rotary tumbling; the water has a lower limit of 10 weight percent, more preferably 20 weight percent, based on the total weight of the binder material, the reinforcing fibers, and the water; an upper limit of 50 weight percent, more preferably 30 weight percent; The concentration range is 60. The method according to any one of appendix 49 to 59.

[0122] <Appendix 61> The binder material is in an amount of 0.5 weight percent to 11 weight percent based on the weight of the reinforcing fibers. 61. The method according to any one of appendix 49 to 60.

[0123] <Appendix 62> the binder material has a lower limit selected from the group consisting of 0.5 weight percent, 1 weight percent, 2 weight percent, 2.5 weight percent, and 3 weight percent, based on the weight of the reinforcing fibers; an upper limit selected from the group consisting of 11 weight percent, 9 weight percent, 7 weight percent, 6 weight percent, and 5 weight percent; In the range of The method of any one of appended claims 49 to 61. One preferred range is 2 weight percent to 6 weight percent of the binder material relative to the weight of the reinforcing fibers, and another preferred range is 2.5 weight percent to 5 weight percent of the binder material relative to the weight of the reinforcing fibers.

[0124] <Appendix 63> the binder material comprises a material selected from the group consisting of polyether polyurethane resin (uncured), polyester polyurethane resin (uncured), maleated polypropylene, polyaryletherketone (PAEK), or epoxy resin (uncured); 63. The method according to any one of appendix 49 to 62.

[0125] <Addendum 64> drying the agglomerate to prepare a dried agglomerate; Preferably, the dried agglomerate comprises 0.5 weight percent water or less, preferably 0.3 weight percent water or less, more preferably 0.2 weight percent water or less. 63. The method according to any one of appendix 49 to 62.

[0126] <Addendum 65> The rotary tumbling includes aligning the reinforcing fibers, said rotary tumbling is carried out for a time such that at least 70 weight percent of said reinforcing fibers in said agglomerate are aligned in an aligned configuration extending in said longitudinal direction within an angle of 20° of the longitudinal direction of said agglomerate, preferentially within an angle of 15°, and more preferentially within an angle of 10° of said longitudinal direction, preferentially within an angle of 15°, and more preferentially within an angle of 15°, and more preferentially within an angle of 15°, and more preferentially within an angle of 15°, and more preferably ... 65. The method according to any one of appendix 49 to 64.

[0127] <Addendum 66> and drying the aggregate after achieving alignment to remove liquid from the aggregate particles. 66. The method according to claim 65.

[0128] <Appendix 67> providing a fiber supply; providing the fiber supply comprises processing a preliminary fiber supply; The step of processing the preliminary fiber supply includes cutting the preliminary form of reinforcing fibers to prepare chopped fibers, and preparing the fiber supply to include at least a portion of the chopped fibers. 67. The method according to any one of appendix 49 to 66.

[0129] <Appendix 68> The step of providing the fiber supply comprises preparing the preliminary fiber supply using recycled reinforcement fibers; preparing the preliminary fiber supply comprises recovering the recycled reinforcing fibers from a composite material; The step of recovering the recycled reinforcing fibers includes a step of liberating the recycled reinforcing fibers from a matrix of the composite material, The method optionally comprises solvating the matrix of the composite material; The method optionally comprises pyrolysis of the matrix of the composite material; The method optionally comprises depolymerizing the matrix of the composite material. 68. The method of any one of claims 67.

[0130] <Appendix 69> a weight average fiber length of the reinforcing fibers in the fiber supply is at least as great as an amount selected from the group consisting of 1 millimeter, 2 millimeters, 3 millimeters, and 4 millimeters; 9. The method according to any one of claims 49 to 68.

[0131] <Appendix 70> The weight average fiber length of the reinforcing fibers in the fiber supply is less than or equal to an amount selected from the group consisting of 18 millimeters, 12 millimeters, 8 millimeters, and 6 millimeters; 70. The particle, bulk product, or method of any one of claims 49 to 69.

[0132] One preferred range for the weight average fiber length in the fiber supply is from 3 millimeters to 8 millimeters, and another preferred range is from 4 millimeters to 6 millimeters. <Appendix 71> classifying the agglomerates to remove a portion of the agglomerates having a property value greater than a property criterion, thereby not including the removed agglomerates in a bulk product comprising the fiber-containing particles. 71. The method according to any one of appendix 49 to 70.

[0133] <Appendix 72> The characteristic criterion is, for example, a maximum agglomerate length between longitudinal ends of the agglomerates to remove agglomerates having a maximum agglomerate length greater than a desired maximum agglomerate length. Method of Appendix 71.

[0134] <Appendix 73> The reinforcing fibers of the fiber supply are free of fiber sizing agents; 73. The method according to any one of appendix 49 to 72.

[0135] <Appendix 74> the reinforcing fibers are provided with a fiber sizing agent; Optionally, the fiber sizing agent is in an amount ranging from 0.5 weight percent to 10 weight percent of the reinforcing fibers comprising the weight of the fiber sizing agent. The method according to any one of appendix 49 to 73.

[0136] <Appendix 75> The method includes the step of preparing the bulk product by treating the aggregate according to any one of claims 13 to 25 and 35 to 48. 5. The method according to any one of claims 49 to 74.

[0137] <Appendix 76> Bulk product prepared according to the method of Appendix 75. <Appendix 77> 75. A bulk product comprising, optionally consisting essentially of, and optionally further comprising particles selected from the group consisting of agglomerates prepared according to the method of any one of claims 49 to 74, modified particles prepared from the agglomerates (e.g., dried and / or hardened agglomerates), and combinations thereof.

[0138] <Appendix 78> consisting essentially of, and optionally comprising, a dried agglomerate (e.g., a dried agglomerate); Bulk products as described in Appendix 77.

[0139] <Appendix 79> The reinforcing fibers are carbon fibers, Optionally, the carbon fibers have a width (e.g., diameter) in the range of 5 microns to 10 microns, preferably 5 microns to 7 microns. 79. The fiber-containing particle, bulk product, or method of any one of claims 1 to 78.

[0140] <Appendix 80> The reinforcing fibers are selected from the group consisting of glass fibers, mineral fibers, natural fibers, carbon nanotubes, polymeric fibers (e.g., aramid fibers, polyamide fibers, or polyolefin fibers), metal fibers, and combinations thereof; 80. The fiber-containing particle, bulk product, or method of any one of claims 1 to 79.

[0141] Possible polyolefin fibers include polypropylene, polyethylene, propylene-ethylene copolymer fibers, as well as high performance polyolefin fibers such as Dyneema® fibers (ultra-high molecular weight polyethylene) and Innegra fibers (high modulus polypropylene). Mineral fibers include basalt, mineral wool, quartz, etc. Some possible natural fibers include bamboo, flax, hemp, jute, or kenaf fibers. Some examples of metal fibers include metal, metal alloy, or intermetallic compounds fibers, with some more specific examples being steel or bronze fibers.

[0142] <Appendix 81> The reinforcing fibers have a weight average fiber width (e.g., diameter) in the range of 0.5 micrometers to 100 micrometers. 81. The fiber-containing particle, bulk product, or method of any one of claims 1 to 80.

[0143] <Appendix 82> The reinforcing fibers include recycled fibers. 82. The fiber-containing particle, bulk product, or method of any one of claims 1 to 81.

[0144] The terms "comprising," "containing," "including," and "having," and grammatical variations thereof, are intended to be inclusive and non-limiting, and the use of such terms indicates the presence of a stated condition or feature but does not exclude the presence of other conditions or features. The use of the terms "comprising," "containing," "including," and "having," and grammatical variations thereof, when referring to the presence of one or more components, subcomponents, or materials, also comprises and is intended to disclose more specific embodiments in which the term "comprising" is used, and is intended to disclose more specific embodiments in which the term "comprising," "containing," or "having" (or variations of such terms) is optionally replaced with any of the narrower terms "consisting essentially of," "consisting of," or "consisting only of" (or any appropriate grammatical variation of such narrower terms). For example, a statement "consisting of" a recited element or elements is intended to include and disclose "consisting essentially of" the recited element or elements, as well as more specific narrower embodiments of "consisting of" the recited element or elements. Examples of various features are provided for illustrative purposes, and terms such as "example," "for example," and the like, set forth non-limiting illustrative examples, and are not to be construed or interpreted as limiting the feature or characteristics to a particular example. A term "at least" followed by a number (e.g., "at least one") means that number or more. "At least a portion" means all or a lesser portion than all. "At least a portion" means all or a lesser portion than all. The term "at least a majority" means a majority portion less than all or a lesser portion than all.As used herein, a weight-based average with respect to a property of an item (e.g., fiber, fiber-containing particles, or bulk product) is equivalent to a mass-based average of the property of the items, which, as will be understood, typically differs from a number-based average of the property of the items (e.g., as a result of differences in mass content between individual items) and a volume-based average (e.g., as a result of density variations between individual items).

Claims

1. 1. A bulk product comprising a plurality of fiber-containing particles, the plurality of fiber-containing particles comprising: 90 weight percent to 99.5 weight percent reinforcing fibers; 0.5 weight percent to 10 weight percent of a binder that holds the reinforcing fibers in a particulate structure; Equipped with Each of the fiber-containing particles comprises: a particle length dimension, the maximum longitudinal separation distance between a first longitudinal end and a second longitudinal end of the fiber-containing particle; a maximum particle width dimension transverse to the longitudinal direction at a longitudinal location between the first longitudinal end and the second longitudinal end; an aspect ratio equal to said particle length dimension divided by said maximum particle width dimension; a dual taper shape comprising a first tapered portion tapering in the longitudinal direction away from the longitudinal location toward the first longitudinal end and a second tapered portion tapering in the longitudinal direction away from the longitudinal location toward the second longitudinal end; It is equipped with In the plurality of fiber-containing particles, the weight average particle length dimension of the fiber-containing particles is in the range of 3 millimeters to 40 millimeters; the weight average particle length dimension is the average, by weight, of the particle length dimensions of the fiber-containing particles; the fiber-containing particles have a weight average aspect ratio of at least 1.5; The weight average aspect ratio is the average, by weight, of the aspect ratios of the fiber-containing particles; Bulk products.

2. The bulk product comprises at least 25 weight percent of the fiber-containing particles.

2. The bulk product of claim 1.

3. The weight average aspect ratio is 6 or less.

3. The bulk product of claim 2.

4. the particle length dimension of at least 75 weight percent of the fiber-containing particles is in the range of 0.5 times the weight average particle length dimension to 2 times the weight average particle length dimension; 4. The bulk product of claim 3.

5. the particle length dimension of at least 2 weight percent of the fiber-containing particles is outside the range of 0.8 times the weight average particle length dimension to 1.2 times the weight average particle length dimension; 5. The bulk product of claim 4.

6. the particle length dimension of at least 98 weight percent of the fiber-containing particles is less than or equal to 3 times the weight average particle length dimension; 6. The bulk product of claim 5.

7. The bulk product has an untapped (free settling) bulk density in the range of 100 grams / liter to 400 grams / liter.

3. The bulk product of claim 2.

8. the bulk product having a tapped bulk density in the range of 200 grams / liter to 650 grams / liter; The tapped bulk density is in the range of 1.2 to 2 times greater than the untapped bulk density.

8. The bulk product of claim 7.

9. The bulk product has an angle of repose in the range of 25° to 45°.

9. The bulk product or method of claim 8.

10. The reinforcing fibers in each of the fiber-containing particles have a weight average fiber length of 75 percent or less of the particle length dimension.

2. The bulk product of claim 1.

11. the weight average fiber length in each of the fiber-containing particles is greater than or equal to 20 percent of the particle length dimension; 11. The bulk product of claim 10.

12. The weight average fiber length is in the range of 1 millimeter to 18 millimeters.

12. The bulk product of claim 11.

13. each of the fiber-containing particles comprises the reinforcing fibers in an aligned configuration with at least 70 weight percent of the reinforcing fibers extending in the longitudinal direction within an angle of 20 degrees of the longitudinal direction; 13. The bulk product of claim 12.

14. each of the first and second tapered portions tapers over a longitudinal distance of at least 20 percent of the longitudinal length within a tapered envelope of a right circular cone; the tapered envelope of the right circular cone has an apex at each of the first longitudinal end and the second longitudinal end and has an opening of 45° or less.

13. The bulk product of claim 12.

15. The bulk product comprises 0.5 weight percent or less of water.

13. The bulk product of claim 12.

16. 1. A method for making a fiber reinforced composite, the method comprising: Dispersing the reinforcing fibers from the fiber-containing particles of the bulk product of any one of claims 1 to 15 into a polymer matrix at a loading in the range of 5 weight percent to 50 weight percent of the reinforcing fibers in the composite material. method.

17. the polymer matrix comprises a thermoplastic polymer; The step of dispersing the reinforcing fibers in the polymer matrix comprises: an extrusion step of extruding a polymeric material for the polymer matrix; adding said fiber-containing particles of said bulk product to said polymeric material during said extrusion process; Equipped with 17. The method of claim 16.

18. The thermoplastic polymer comprises a member selected from the group consisting of polyamide, polypropylene, polyethylene, polyethylene terephthalate, polylactic acid, polycarbonate, acrylonitrile butadiene styrene, polystyrene, and polyaryletherketone.

20. The method of claim 17.

19. The method further comprises pelletizing an extrudate from the extrusion to prepare pellets comprising the reinforcing fibers dispersed in the polymer matrix; The extrudate comprises the reinforcing fibers dispersed in the polymer matrix.

20. The method of claim 18.

20. The method further comprises injection molding the pellets of material into a product form.

20. The method of claim 19.

21. A method for producing a bulk product according to any one of claims 1 to 15, comprising the steps of: The method comprises processing a fiber supply and a binder material to prepare the fiber-containing particles, the fiber-containing particles comprising fibers from the fiber supply, the fiber supply comprising the reinforcing fibers in a non-continuous form; said step of treating said fiber supply and said binder material comprises tumbling a mixture of said reinforcing fibers and said binder material to form agglomerates, each agglomerate comprising a portion of said reinforcing fibers and a portion of said binder material. method.

22. Processing the mixture includes placing the reinforcing fibers and the binder material in a processing vessel; The step of tumbling the mixture comprises rotating the treatment vessel containing the reinforcing fibers and the binder material.

22. The method of claim 21.

23. said step of rotary tumbling said mixture comprises rotating said treatment vessel at a tangential velocity on an inner surface of a wall of rotation of said treatment vessel in the range of 0.3 to 1.4 meters per second; said step of rotary tumbling said mixture being carried out for a period of time ranging from at least 15 minutes to at most 240 minutes; 23. The method of claim 22.

24. the supply of binder material to the step of treating the fiber supply and the binder material comprises a binder precursor composition comprising the binder material dispersed in a carrier liquid.

23. The method of claim 22.

25. said step of treating said fiber supply and said binder material comprises combining all or a portion of said binder precursor composition with said reinforcing fibers prior to said step of tumbling said mixture.

25. The method of claim 24.

26. and treating the fiber supply and the binder material includes introducing some or all of the binder precursor composition into the treatment vessel after the reinforcing fibers have been introduced into the treatment vessel while the treatment vessel is rotating.

25. The method of claim 24.

27. the step of treating the fiber supply and the binder material comprises evaporating at least a portion of the carrier liquid during a time period selected from the group consisting of after contacting the binder precursor composition with the reinforcing fibers, during the step of tumble the mixture, after the step of tumble the mixture, and combinations thereof.

25. The method of claim 24.

28. The step of evaporating at least a portion of the carrier liquid comprises heating the reinforcing fibers and the carrier liquid to a temperature of at least 100° C.

28. The method of claim 27.

29. The carrier liquid is an aqueous liquid.

29. The method of claim 28.

30. The step of treating includes combining a binder material, reinforcing fibers, and water prior to completing the rotary tumbling; the water has a concentration ranging from 10 weight percent to 50 weight percent based on the total weight of the binder material, the reinforcing fibers, and the water; 30. The method of claim 29.

31. The method further comprises drying the agglomerates to prepare dried agglomerates having 0.5 weight percent water or less. The method of claim 30.

32. the binder material is in an amount of 0.5 weight percent to 11 weight percent based on the weight of the reinforcing fibers; 22. The method of claim 21.

33. the binder material comprises a material selected from the group consisting of polyether polyurethane resin (uncured), polyester polyurethane resin (uncured), maleated polypropylene, polyaryletherketone (PAEK), or epoxy resin (uncured); 33. The method of claim 32.

34. The method further comprises providing a fiber supply; providing the fiber supply comprises processing a preliminary fiber supply; The step of treating the preliminary fiber supply comprises: Preparing cut fibers by cutting the preform of reinforcing fibers; preparing the fiber supply to comprise at least a portion of the cut fibers; Equipped with 22. The method of claim 21.

35. The step of providing the fiber supply comprises preparing the preliminary fiber supply using recycled reinforcement fibers; preparing the preliminary fiber supply comprises recovering the recycled reinforcing fibers from a composite material; The step of recovering the recycled reinforcement fibers includes removing the recycled reinforcement fibers from a matrix of the composite material.

35. The method of claim 34.

36. The weight average fiber length of the reinforcing fibers in the fiber supply ranges from 1 millimeter to 18 millimeters; 22. The method of claim 21.

37. The method further comprises classifying the agglomerates to remove a portion of the agglomerates having a length greater than a maximum particle length criterion.

37. The method of claim 36.

Images