Fiber reinforced tape

Abstract

Fiber-reinforced tapes can have a thermoplastic resin and a plurality of unidirectional continuous twisted fiber yarns, e.g., carbon fiber yarns, embedded in the thermoplastic resin. Each of the plurality of unidirectional continuous fiber yarns can include 1,000 to 100,000 fibers, e.g., carbon fibers, and each of the fiber yarns can have 4 to 400 twists per meter in a length direction. The tape can have 0.1 to 2 yarn ends per mm in the cross direction. Composites can be formed from multiple layers of the fiber reinforced tape. Advantageously, such tape and composites have high strength and flexibility and can be used to reinforce high pressure pipe.

Description

FIBER REINFORCED TAPECLAIM OF PRIORITY

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 594,800 bearing Attorney Docket Number 1202320 and filed om October 31, 2023, which is hereby incorporated by reference in its entirety.TECHNICAL FIELD

[0002] The present disclosure is directed to a fiber-reinforced tape including unidirectional continuous twisted fiber yarns, e.g., carbon fiber yarns, embedded in a thermoplastic resin and layered composites made from such fiber reinforced tape. Such fiber-reinforced tapes can be used for high-pressure pipe reinforcement and / or rehabilitation.BACKGROUND

[0003] Fiber-reinforced tapes find use in many applications including reinforcing pipe. For example, the tape can be wrapped around an inner or outer section of a pipe to increase or maintain the strength of the pipe. Conventional tapes employ thermosetting resins to help achieve the desired strength. However, thermosetting resins can be difficult to implement with tapes and generally have poor adhesive properties for forming layers with other materials. In addition, to increase the strength of the reinforcement, reinforcing tape is typically applied in several layers which reduces its flexibility.

[0004] Hence, there is a continuing need for developing fiber-reinforced tape to balance strength and flexibility.SUMMARY OF THE DISCLOSURE

[0005] Advantages of the present disclosure include a fiber-reinforced tape with high strength and flexibility. The fiber-reinforced tape comprises a thermoplastic resin and a plurality of unidirectional continuous fiber yams embedded in the thermoplastic resin. Advantageously, theplurality of unidirectional continuous fiber yams can be twisted, e.g., the plurality of unidirectional continuous yams has 4 to 400 twists per meter in a length direction.

[0006] In certain aspects of the present disclosure, the fiber-reinforced tape can have a width in a cross direction in the range of 6 mm to 1525 mm. The fiber-reinforced tape can also have 0.1 to 2 yarn ends per mm in the cross direction. Advantageously, the plurality of unidirectional continuous fiber yarns can be composed of carbon fibers such as from about 1,000 to about 100,000 carbon fiber filaments.

[0007] In other implementations, a fiber-reinforced tape can comprises a thermoplastic resin and a plurality of unidirectional continuous fiber yarns embedded in the thermoplastic resin. The plurality of unidirectional continuous fiber yams comprises a first twisted fiber yarn and a second twisted fiber yam, and the first twisted fiber yarn and the second twisted fiber yam have a different number of twists per meter in the length direction.

[0008] In certain aspects, the second twisted fiber yarn comprises at least one of a glass fiber yam, aramid fiber yam, basalt fiber yarn, an ultra high molecular weight polyethylene fiber yam, a liquid crystal polymer fiber yam, a poly(p-phenylene-2,6-benzobisoxazole) fiber yam, a cellulose fiber yarn, a rayon yam, or a combination thereof.

[0009] In further implementations, a composite can comprise two or more layers of a fiber- reinforced tape of the present disclosure. For example, the fiber reinforced tape can include (a) a thermoplastic resin; and a plurality of unidirectional continuous fiber yarns embedded in the thermoplastic resin, wherein the fiber-reinforced tape has a width in a cross direction in a range of 6 mm to 1525 mm, and has 0.1 to 2 yarn ends per mm in the cross direction; and wherein each of the plurality of unidirectional continuous fiber yarns comprises 1,000 to 100,000 carbon fibers and each of the plurality of unidirectional continuous fiber yarns has 4 to 400 twists per meter in a length direction, or (b) a thermoplastic resin; and a plurality of unidirectional continuous fiber yams embedded in the thermoplastic resin, wherein the plurality of unidirectional continuous fiber yarns comprises a first twisted fiber yarn and a second twisted fiber yarn, and the first twisted fiber yarn and the second twisted fiber yam have a different number of twists per mm in the length direction, or a combination of (a) and (b).

[0010] Another implementation includes a pipe having a reinforcing layer in which the reinforcing layer includes at least one fiber-reinforced tape of the present disclosure.

[0011] Additional advantages of the present disclosure will become readily apparent to those skilled in this art from the following detailed description, wherein only certain embodiment are shown and described, simply by way of illustration of carrying out certain subject matter. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various respects, all without departing from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Reference is made to the attached drawings, wherein elements having the same reference numeral designations represent similar elements throughout and wherein:

[0013] FIG. 1 A and FIG. IB are schematic illustrations of a fiber reinforced tape according to an implementation of the present disclosure. FIG. IB illustrates a cross sectional view of the tape of FIG. 1A.

[0014] FIG. 2A, FIG. 2B and FIG. 2C illustrate a conventional tape with impregnated fiber filaments. FIG. 2A shows an image of a top view of the conventional tape, FIG. 2B shows a cross sectional image of the conventional tape and FIG. 2C schematically illustrates a cross sectional image of the conventional tape.

[0015] FIG. 3A, FIG. 3B and FIG. 3C illustrate a fiber reinforced tape of the present disclosure according to one or more implementations. FIG. 3A shows an image of a top view of the tape, FIG. 3B shows a cross sectional image of the tape and FIG. 3C schematically illustrates a cross sectional image of the tape of the present disclosure.

[0016] FIG. 4 is a schematic showing potential relative orientations of fiber yarns in layers of fiber reinforced tapes of the present disclosure.

[0017] FIG. 5 illustrates perspective views of a composite including three layers of fiber reinforced tape in which the fiber yams in the tape layers are relatively aligned in 0-0-0 orientation (i.e., all fiber yams are aligned along the Z-axis).

[0018] FIG. 6 illustrates perspective views of a composite including three layers of fiber reinforced tape in which the fiber yarns in the tape layers are relatively aligned in a 0-90-0 orientation (i.e., alternating tapes are rotated 90° from the Z-axis).

[0019] FIG. 7 illustrates perspective views of a composite including two layers of fiber reinforced tape in which the fiber yarns in the tape layers are relatively aligned in 45°-45° orientation (i.e., the first (top) tape layer is rotated a positive 45° from the Z-axis and the second (bottom) tape layer is rotated a negative 45° from the Z-axis such that the fiber yarns in one tape layer are oriented perpendicular to the adjacent tape layer).

[0020] FIG. 8 illustrates perspective views of a composite including three layers of fiber reinforced tape in which the fiber yarns in the tape layers are relatively aligned in a 0°-45°-45° orientation (i.e., the fiber yarns of the top tape layer are aligned along the Z- axis and each subsequent tape layer is rotated a positive and negative 45° from the Z-axis such that the fiber yams in the middle layer are oriented perpendicular to the fiber yarns in the bottom tape layer).

[0021] FIG. 9 is a schematic illustration of a pipe having a reinforcing layer composed of one or more fiber reinforced tapes of the present disclosure.

[0022] FIG. 10 illustrates flexural testing of composites according to ASTM D790.DETAILED DESCRIPTION OF THE DISCLOSURE

[0023] The disclosure may be more fully appreciated by reference to the following description, including the following definitions and examples. Certain features of the disclosed compositions and methods which are described herein in the context of separate aspects, may also be provided in combination in a single aspect. Alternatively, various features of the disclosed compositions and methods that are, for brevity, described in the context of a single aspect, may also be provided separately or in any sub-combination.

[0024] Unless otherwise defined herein, scientific and technical terms used in connection with the present application shall have the meanings that are commonly understood by those of ordinary skill in the art. Further, unless otherwise required by context, singular terms shall include pluralities and plural terms shall include the singular.

[0025] As employed above and throughout the disclosure, the following terms and abbreviations, unless otherwise indicated, shall be understood to have the following meanings.

[0026] As used in the specification including the appended claims, the singular forms “a,” “an,” and “the” include the plural, and reference to a particular numerical value includes at least that particular value, unless the context clearly dictates otherwise.

[0027] The present disclosure is directed to a fiber-reinforced tape that includes a thermoplastic resin, and a plurality of unidirectional, continuous twisted fiber yarns embedded in the thermoplastic resin. As used herein, a tape is a continuous narrow strip and the term can be used interchangeably with a belt, or a ribbon. FIG. 1A illustrates a fiber-reinforced tape according to certain aspects of the present disclosure and FIG. IB illustrates a cross sectional view of the tape in FIG. 1A. As illustrated, tape 100 includes a plurality of fiber yams 110 embedded in a thermoplastic resin 120. Further, each yarn includes a plurality of fibers, i.e., filaments (160). The yams are unidirectional and continuous and, although not illustrated for convenience, the yams are twisted. As shown with reference to the Z, X and Y axes, the tape can have a length in the Z direction, a width (130) in the X direction and a thickness in the Y direction. The tape length can be greater than or similar to its width, but the tape thickness is substantially less than either its length or width. For example, the fiber-reinforced tape can have a width in a cross direction in a range of about 6 mm to about 1525 mm (about 0.25 inches (in) to about 60 in), such as from 10 mm, 15 mm, 20 mm, 25 mm, 50 mm, 75 mm, 100 mm, 150 mm, 200 mm, 250 mm to about 1525 mm, 1500 mm, 1400 mm, 1300 mm, 1200 mm, 1000 mm, 900 mm, 500 mm, 200 mm, or any value or range therebetween. Moreover, the fiber reinforced tape can have a thickness (Y direction) in a range of about 0.75 mm to about 5 mm (about 0.03 in to 0.2 in), such as from about 0.75 mm, or 1 mm to about 3 mm, 4 mm, 5 mm, or any value or range therebetween.

[0028] As further shown in the FIG. IB, the tape can have a certain number of yarn ends per millimeter (mm) (140) in the width or cross direction (X direction). The yarn ends per mm of the tape is an indication of the packing of the yams in the tape. In certain implementations, the fiber- reinforced tape can have about 0.1 to about 2 yam ends per mm (2 to 50 yarn ends per inch) in the cross direction, such as from about 0.2, 0.5, 0.7 to about 2, 1.5, 1 yarn ends per mm in the cross direction or any value or range therebetween.

[0029] As used herein, a fiber yarn, also referred to as a tow, or roving, is a continuous untwisted bundle of fibers. The fiber yarn can include from about 1,000 to about 100,000 of individual fibers, which can also be referred to as filaments. The number of fibers in a yarn can be designated as 3k, 6k, 12k, and 15k in which “k” stands for “thousand” such that a 3k yam has 3,000 filaments. In some aspects of the present disclosure, continuous fiber yams can include from about 1,000 fibers to about 100,000 fibers, e.g., from about Ik, 6k, 12k, 15k, 20k fibers to about 90k, 70K, 50k fibers, or values or ranges therebetween. Individual fibers can be held together and / or protected by an organic coating, a sizing, or combinations thereof.

[0030] Further, the continuous fiber yarns can be twisted together in a helical arrangement with either an S-twist (the threads appear to go “up” to the left) or Z-twist (the threads appear to go “up” to the right). The twist direction of the yarn, and the amount of twisting, can affect the final properties of the yam and tape. By twisting a yam, physical cohesion of individual filaments is introduced, which affects both ease of handling as well as some mechanical properties. While not all fibers will behave the same after being twisted, it is believed that twisting increases the strength of a fiber yarn (up to a certain twist level), decreases its modulus, and increases its elongation.

[0031] In some aspects of the present disclosure, each of the plurality of unidirectional continuous yarns can have about 4 to about 400 twists per meter (0.1 to 10 twists per inch) in a length direction of the yam. For example, each of the plurality of unidirectional continuous yarns can have about 4, 8, 12, 16, 20, 24, 28, 32, 36, 40 to about 400, 360, 320, 280, 240, 200 twists per meter in a length direction of the yarn or any value or range therebetween.

[0032] Further, the twisted fiber yams implemented in the tapes of the present disclosure can have different numbers of twists per meter. That is, in some aspects, a plurality of unidirectionalcontinuous fiber yams embedded in a thermoplastic resin of a tape of the present disclosure can have a first twisted fiber yarn with a different number of twists per meter in the length direction than a second twisted fiber yam or even a third or fourth twisted fiber yarn.

[0033] In some implementations of the present disclosure, the plurality of unidirectional continuous fiber yams are composed of carbon fibers, e.g., the plurality of unidirectional continuous fiber yams are carbon fiber yams. In addition, the plurality of unidirectional continuous fiber yams can include more than one type of yam materials. For example, the plurality of unidirectional continuous fiber yams in a tape of the present disclosure can comprise a first twisted fiber yam, e g., composed of carbon fibers, and a second twisted fiber yarn composed of fibers of a different material and even a third and fourth twisted fiber yarn composed of yet different materials. In some aspects, the additional twisted fiber yam or yarns, e.g., second twisted fiber yam, can be one or more of a glass fiber yarn, aramid fiber yarn, basalt fiber yam, an ultra high molecular weight polyethylene fiber yam, a liquid crystal polymer fiber yam, a poly(p- phenylene-2,6-benzobisoxazole) fiber yam, a cellulose fiber yarn, a rayon yam, or any combination thereof.

[0034] In some implementations, the elongation at break of the first twisted fiber yarn can be substantially the same as the elongation at break of the second twisted fiber yarn, e.g., within 5%. In other aspects, the elongation at break of the first twisted fiber yam can be within 10%, 15%, 20% of the elongation at break of the second twisted fiber yarn.

[0035] As further shown in the FIG. IB, the plurality of fiber yarns are not completely impregnated with the thermoplastic resin. That is, the fiber yarns (110) have a minimal amount of thermoplastic resin (120) among yam filaments (160). Employing twisted fiber yarn in the fiber- reinforced tape of the present disclosure allows many individual fiber filaments to directly contact each other with minimal resin infiltrating the volume of the yarn. Such an unimpregnated yam structure contrasts with an impregnated fiber tape, which has individual fiber filaments spread apart with resin infiltrated in the space between fiber filaments. Further, by embedding the plurality of continuous twisted fiber yams with resin, as opposed to impregnating the yarns with resin, the tape has relatively less resin and relatively more yarn by weight of the tape, which leadsto a high strength, yet flexible tape. Moreover, in some aspects, the continuous twisted fiber yarns can contact both an upper and lower surface of the tape.

[0036] FIGS. 2A-2C illustrate a conventional tape (200) with resin (220) impregnated fibers (260). FIG. 2A shows an image of a top view of the tape (200), FIG. 2B shows a cross sectional image of the conventional tape and FIG. 2C schematically illustrates a cross sectional image of the conventional tape. As shown in the figures, the resin (220) in the conventional tape is included between fiber filaments 260 in the tape. In contrast, a fiber reinforced tape of the present disclosure can have a plurality of fiber yarns embedded in a resin (rather than impregnated with resin). FIGS. 3A-3C exemplify such a structure. As shown in FIGS. 3A-3C, a fiber reinforced tape (300) can have a plurality of fiber yarns (310) embedded in a thermoplastic resin (320) (rather than impregnated with the resin). As illustrated in FIG. 3C, the example tape (300) can have minimal resin (320) between filaments (360). Such a configurations uses substantially less resin and allows for a more flexible tape.

[0037] Thermoplastic resins useful for preparing tapes of the present disclosure include, for example, a polyolefin, such as a polyethylene, a poly (ethylene- vinyl acetate), or a combination thereof. Other resins useful for preparing tapes of the present disclosure include, for example, a polyester and copolymers thereof, a polyamide, a polyvinyl chloride, a polyurethane, thermoplastic vulcanizate, a polyetheretherketone, a polyetherimide, a polyphenylene sulfide, a polyacrylate such as polymethyl methacrylate, or combinations thereof. Advantageously, the thermoplastic resin allows the tape to be reprocessed by heat for reshaping or bonding. Thermoplastic resins also allows the tape to be recycled.

[0038] As explained above, the fiber reinforced tapes of the present disclosure advantageously can have a relatively low amount of resin to maintain flexibility. In some aspects, the fiber- reinforced tape includes, based on the total weight of the fiber-reinforced tape, from about 5 wt% to about 80 wt% of the thermoplastic resin, and from about 20 wt% to about 95 wt% of the plurality of unidirectional continuous twisted fiber yams. For example, the fiber-reinforced tape can include, based on the total weight of the fiber-reinforced tape, from about 5 wt% to about 35 wt%of the thermoplastic resin, and from about 65 wt% to about 95 wt% of the plurality of unidirectional continuous twisted fiber yarns.

[0039] Further, fiber-reinforced tapes of the present disclosure can have higher porosity than conventional fiber reinforced tapes. For example, fiber-reinforced tapes of the present disclosure can have a porosity in the range of from about 15% to 50%, such as from about 17% to about 47% of porosity. Porosity can be determined by Computer Tomography (CT) Scanning.

[0040] In some aspects, a fiber-reinforced tape of the present disclosure can have an areal weight in the range of about 100 g / m2to about 5000 g / m2, such as from about 1000 g / m2to about 2500 g / m2.

[0041] In other aspects, a fiber-reinforced tape of the present disclosure can have a tensile elongation in the range of about 2% to about 10%, such as in a range of from about 5% to about 10%.

[0042] A fiber-reinforced tape of the present disclosure can also be used to form composites. Such composites can include two or more layers of the fiber-reinforced tape of the present disclosure. Advantageously, the two or more layers of the fiber-reinforced tape can be adhered to one another through the thermoplastic resin to form a composite laminate.

[0043] In addition, the fiber yarns in the various tape layers of a composite can be oriented in the same or different direction relative to each layer. For example, a composite can include a first layer of fiber-reinforced tape in which the plurality of unidirectional continuous fiber yams are oriented in a first direction and a second layer of fiber-reinforced tape in which the plurality of unidirectional continuous fiber yams are oriented at an angle greater than or equal to 0° and less than or equal to 90° with reference to the plurality of unidirectional continuous fiber yams in the first layer of fiber-reinforced tape. The composite can include additional layers of fiber reinforced tape of the present disclosure in which the fiber yarns in the additional layers can be oriented at an angel of > 0° and < 90° to fiber yarns in adjacent layers of tape in the composite.

[0044] FIGS. 4-8 illustrate various composites and relative orientations of fiber yarns in the layers of the tape that form the composite. For example, FIG. 4 illustrates various orientations offiber yams in a composite with two or three layers of fiber reinforced tape of the present disclosure. These orientations include 0-0-0, 0-90-0, 45-45 (i.e., a positive 45 degree rotation and a negative 45 degree rotation), and 0-45-45. Additional relative orientations are also contemplated by the present disclosure include 0-67, etc.

[0045] FIG. 5 illustrates perspective views of a composite (500) including three layers of fiber reinforced tape (502, 504, 506) in which the fiber yarns in the tape layers are relatively aligned in 0-0-0 orientation. As exemplified in this figure, the plurality of fiber yarns in a first tape (502) are oriented in a first direction, i.e., the Z direction (longitudinal direction) or 0° from the Z axis. A second tape layer (504) and third tape layer (508) are combined in such that the fiber yams in each tape layer are oriented along the same Z direction thus producing a composite of three tape layers with each layer having its fiber yams oriented in the same Z direction.

[0046] FIG. 6 illustrates perspective views of a composite (600) including three layers of fiber reinforced tape (602, 604, 606) in which the fiber yarns in the tape layers are relatively aligned in a 0-90-0 orientation. As exemplified in this figure, the plurality of fiber yarns in a first tape (602) are oriented in a first direction, i.e., the Z direction (longitudinal direction) and second tape layer (604) has its fiber yams oriented at an angle of 90° from the orientation of the fiber yarns in the first tape (602), i.e., the fiber yams in the second tape are oriented at an angle of 90° from the Z- axis or an angle of 0° from the X axis. The third tape layer (606) has its fiber yarns oriented at an angle of 0° from the orientation of the fiber yarns in the first tape (602).

[0047] FIG. 7 illustrates perspective views of a composite (700) including two layers of fiber reinforced tape (702, 704) in which the fiber yams in the tape layers are relatively aligned in 45- 45 orientation. As exemplified in this figure, the plurality of fiber yarns in a first tape (702) are oriented in a first direction, i.e., the tape and fiber yarns are rotated a positive 45° from the Z-axis. The second layer (704) has its fiber yams rotated a negative 45° from the Z-axis such that the fiber yarns in the first tape (702) are oriented perpendicular (90°) to the fiber yarns in the second tape layer (704).

[0048] FIG. 8 illustrates perspective views of a composite (800) including three layers of fiber reinforced tape (802, 804, 806) in which the fiber yarns in the tape layers are relatively aligned ina 0-45-45 orientation. As exemplified in this figure, the plurality of fiber yarns in a first tape (802) are oriented in a first direction, i.e., the Z direction (longitudinal direction) or 0° from the Z axis. The second tape layer (804) and third tape layer (806) is rotated a positive and negative 45° from the Z-axis, respectively, such that the fiber yarns in the second tape layer (804) are oriented perpendicular to the fiber yams in the third tape layer (806). Each of the composites illustrated in FIGS. 5-8 can be formed into laminates of the composites by the application of heat.

[0049] In some aspects, a composite or laminate thereof of the present disclosure can have a flexural strength in the range of from about 1 MPa to about 50 MPa, such as from about 10 MPa to about 20 MPa. In other aspects, a composite or laminate thereof of the present disclosure can have a flexural modulus in the range of about 0.1 GPa to about 15 GPa, such as from about 1 GPa to about 5 GPa.

[0050] Another aspect of the present disclosure includes piping reinforced by one or more fiber reinforced tapes or laminated composites of the present disclosure. Tensile fatigue resistance of a tape is a consideration in applications such as pipe reinforcement since hoop stress (and subsequently tensile failure) can cause failure in high pressure pipe applications. However, fiber reinforced tapes of the present disclosure can have or be layered to have sufficient strength for reinforcing piping such as high pressure piping for carrying gases such as natural gas or hydrogen. Further, fiber reinforced tapes of the present disclosure are sufficiently flexible to allow for installation of tape to existing piping in the field thereby allowing rehabilitating and / or repairing existing pipe in the field.

[0051] FIG. 9 illustrates a reinforced pipe having a reinforcing layer composed of one or more fiber reinforced tapes of the present disclosure. As shown for this example, pipe 900 includes three layers, an outer layer or jacket (910), a reinforcing layer (912) and an optional an inner liner (914). The outer jacket can be composed of a metal such as steel, or a plastic. The reinforcing layer can be composed of at least one fiber-reinforced tape of the present disclosure. In addition, the reinforcing layer can be composed of several layers of such tapes such as two, three, four, five, six, seven, etc. fiber-reinforced tapes of the present disclosure. In an aspect of the presentdisclosure, the one or more fiber-reinforced tapes can be helically wrapped along a longitudinal direction of the pipe, i.e., in the direction of the Z axis which is out of the plane of the figure.

[0052] The inner layer can be composed of a polyolefin, such as a polyethylene, polypropylene, a polyvinylidene fluoride, a polyvinyl chloride, a polycarbonate, a polyamide, a polyurethane, etc. or any combination thereof.

[0053] While FIG. 9 illustrates a three layer construct with a reinforcing middle layer, a reinforced pipe can have a reinforcing layer on the pipe such that the pipe can be composed of a metal or plastic and the reinforcing layer can be on an outer surface of the pipe.

[0054] Further, the reinforcing layer can include one or more fiber reinforced tapes of the present disclosure helically wrapped in which the fiber yarns are oriented at an angle from > 0° and < 90 relative to a longitudinal direction of the pipe, i .e., in the direction of the Z axis which is out of the plane in FIG. 9.EXAMPLES

[0055] Testing was performed on fiber reinforced tapes having fiber yarns that were untwisted or twisted. Composite structures were formed by laminating layers of tape and tested.

[0056] Comparative Example (Impregnated Composites with Untwisted Yam)

[0057] Untwisted 24K filament single end roving carbon fibers were pulled along the machine direction of a composite tape processing line. Polymer melt (high density polyethylene) was fed into a crosshead impregnation die geometry and consolidated with the carbon fiber rovings before being cooled and wound onto a core, resulting in a polymer impregnated unidirectional carbon fiber tape. Tensile properties of the tape were tested by cutting strips of tape to 19mm width and 1200mm length and pulled at lOmm / min testing speed in a universal testing machine with split capstan grips according to ASTM D3039 (Standard Test Method for Tensile Properties of Polymer Matrix Composite Materials).

[0058] Flexural properties of composite were tested by laminating 6-12 layers of tape in a platen press with layers all in the fiber direction or layers alternating between the fiber direction and 45-90° to the fiber direction. These laminates were cut to 12mm width by 64mm length bars by wateijet and bent on a universal testing machine at 12mm / min testing speed and a span / depth ratio of 16: 1 according to ASTM D790 (Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials).

[0059] Example 1 (Twisted Fiber Reinforced Tape Composites)

[0060] 24K filament single end roving carbon fibers were twisted in the S or Z direction on a ring twister to about 0.02 twists per mm (about 20 twists per meter) in the machine direction (length direction). These discrete twisted rovings were pulled along the machine direction of a composite tape processing line. Polymer melt (high density polyethylene) was fed into a crosshead impregnation die geometry and consolidated with the twisted carbon fiber rovings before being cooled and wound onto a core, resulting in an unimpregnated twisted carbon fiber tape. The process was designed to result in an unimpregnated tape by not engaging the crosshead impregnation die geometry, i.e., the fibers were pulled through the open channel in a pultrusionlike process. This process used the same equipment and geometry as the impregnated fiber yam tape, only that impregnation process has the impregnation geometry in the die fully engaged, where the fibers fully interacted with the die and created a driving force to infiltrate melt into the fibers.

[0061] Tensile properties of these tapes were determined by pulling them at a 63.5 mm / min testing speeds on a universal testing machine according to ASTM D6775 (Standard Test Method for Breaking Strength and Elongation of Textile Webbing, Tape and Braided Material).

[0062] Flexural properties of the composite were tested by laminating 2-3 layers of tape in a platen press with layers all in the fiber direction or layers alternating between the fiber direction and 45-90° to the fiber direction. These laminates were cut to 12mm width by 64mm length bars by wateijet and bent on a universal testing machine at 12mm / min testing speed and a span / depth ratio of 16: 1 according to ASTM D790.

[0063] The physical properties of the untwisted and twisted tape constructions were compared. Layers of untwisted and twisted carbon fibers tapes were loaded into a thermoplastic resin to achieve equivalent tensile strengths. A fiber loading of about 60 wt% fiber to about 40 wt% thermoplastic resin was obtained with a untwisted fiber yarn tape, while a fiber loading of 80% was obtained with the twisted carbon fiber tape construction. The resulting higher wt% of carbon fiber yarn results in a significantly higher areal weight of 1350 g / m2and thickness (1 mm) as summarized in Table 1. Thus, the fiber reinforced tape with twisted yam has certain advantageous properties in relation to strength and areal weight.Table 1. Properties of fiber reinforced tapes that make up the laminates.

[0064] The mechanical properties of the untwisted fiber tape and a twisted fiber tape were compared using a universal testing machine and summarized in Table 2 below.Table 2. Mechanical properties of fiber reinforced tapes that make up the laminates.

[0065] Although the tapes were constructed to have similar tensile strength of about 1600 MPa, the twisted carbon fiber yarn tape construction showed significantly higher elasticity compared to untwisted carbon fiber yarn tape (elongation of 10.5% versus 1.7%) and also showed significantly higher maximum load strength (160 kg / mm versus 25 kg / mm).

[0066] For the untwisted carbon fiber yarn tape construction, the ASTM D3039 tensile testing method was used to measure the force required to break a polymer composite specimen and the extent to which the specimen stretches or elongates to that breaking point. D3039 was more suitable for a rigid thermoset composite. The breaking strength and elongation of the twisted carbon fiber yarn tapes were measured using the ASTM D6775 test method.

[0067] Composites

[0068] Laminate composites were prepared by stacking carbon fiber impregnated tapes in an offset orientation, where the orientation in degrees refers to the relative directional change in the longitudinal axis (e.g., Z axis of FIGS. 5-8) of the carbon fiber yams in each tape layer. Compositestacks were prepared by orienting the carbon fiber yams in a layer in a parallel oriented stack (0- 0-0), a perpendicular stack (0-90-0), a cross-directional orientation with respect to the longitudinal axis with the carbon fiber yarns in a tape layer oriented perpendicular to the carbon fiber yams in the underlying layer (45-45), and a cross-direction 45-45 stack with an additional top layer with a zero-degree orientation for the carbon fiber yams in the tape relative to the Z-axis. Orientation of the carbon fiber tapes with respect to the carbon yarns are shown in Table 1. As further shown in Table 1, tapes constructed from twisted carbon fiber were thicker than the unidirectional carbon fiber tapes. Thus, to compare flexural strength on composites with similar thicknesses, laminates were prepared with 12 layers for the unidirectional tape construction and 3 layers for the twisted carbon fiber tape construction, except for the 45-45 orientation which was constructed with only 2 layers and compared to a 3-layer laminate with a 0-45-45 layer orientation.

[0069] Flexural strength of laminated composites prepared from the untwisted and twisted carbon fiber yam tapes were measured on a universal testing machine using the ASTM D790 test method and are summarized in Table 3 below.Table 3: Flexural strength of tapes that make up the laminates.

[0070] Laminate composites prepared from fiber reinforced tapes including a plurality of continuous twisted carbon fiber yams showed lower flexural strength, modulus, and maximum load at failure compared to laminate composited prepared from tapes having untwisted yam.

[0071] All orientations of laminate composites showed significantly more flexibility (flexural modulus) when using twisted fiber yarns, while having similar tensile strength of tapes with untwisted yarns. When used in a reinforcing construction, the laminates with twisted fiber yam will provide more flexibility in the final construction while having comparable tensile strength to a corresponding laminate composite composed of untwisted fiber yam tape.

[0072] Thus, composites and laminates thereof prepared with fiber reinforced tapes including a plurality of continuous twisted carbon fiber yams advantageously have high tensile strength but has significantly better flexural strength and modulus compared to an approximately equivalent composite prepared from fiber reinforced tape with untwisted yarn. Such laminated composites of the present application are further advantageous in reducing the weight of the laminate for a given strength.

[0073] Flexural testing according to ASTM D790 included a Span / thickness ratio of 16: 1 and test speed of 0.5 in / min. As illustrated in FIG. 10, such testing was carried out on a stack of multiple layers of fiber reinforced tape (1010) in which the bending location (1012) was centered over the stack and the test span supports (1014a, 1014b) resulted in a Span / thickness ratio of 16: 1.

[0074] Only certain features and aspects of the present disclosure and examples of their versatility are shown and described in the present disclosure. It is to be understood that the technology disclosed herein is capable of use in various other combinations and environments and is capable of changes or modifications. Thus, for example, those skilled in the art will recognize, or be able to ascertain, using no more than routine experimentation, numerous equivalents to thespecific substances, procedures and arrangements described herein. Such equivalents are considered to be within the scope of the invention and are covered by the following claims.

Claims

WHAT IS CLAIMED IS:1 . A fiber-reinforced tape comprising: a thermoplastic resin; and a plurality of unidirectional continuous fiber yams embedded in the thermoplastic resin, wherein the fiber-reinforced tape has a width in a cross direction in a range of 6 mm to 1525 mm, and has 0.1 to 2 yarn ends per mm in the cross direction; and wherein each of the plurality of unidirectional continuous fiber yams comprises 1,000 to 100,000 carbon fibers and each of the plurality of unidirectional continuous fiber yams has 4 to 400 twists per meter in a length direction.

2. The fiber-reinforced tape of claim 1, wherein the fiber-reinforced tape comprises, based on a total weight of the fiber-reinforced tape:5 wt% to 80 wt% of the thermoplastic resin; and20 wt% to 95 wt% of the plurality of unidirectional continuous fiber yarns.

3. The fiber-reinforced tape of claim 1, wherein the fiber-reinforced tape comprises, based on a total weight of the fiber-reinforced tape:5 wt% to 35 wt% of the thermoplastic resin; and65 wt% to 95 wt% of the plurality of unidirectional continuous fiber yarns.

4. The fiber-reinforced tape of any one of claims 1 -3, wherein the fiber reinforced tape has a thickness in the range of 0.75 mm to 5 mm.

5. The fiber-reinforced tape of any one of claims 1-3, wherein the thermoplastic resin comprises a polyolefin.

6. The fiber-reinforced tape of any one of claims 1-3, wherein the thermoplastic resin comprises a polyethylene.

7. The fiber-reinforced tape of any one of claims 1-3, wherein the thermoplastic resin comprises a poly (ethylene-vinyl acetate).

8. The fiber-reinforced tape of any one of claims 1-3, wherein the fiber-reinforced tape has a porosity in the range of 17% to 47% as determined by Computer Tomography (CT) Scanning.

9. The fiber-reinforced tape of any one of claims 1-3, wherein the fiber-reinforced tape has a tensile elongation in a range of 2% to 10%.

10. The fiber-reinforced tape of any one of claims 1-3, wherein the fiber-reinforced tape has an areal weight in the range of 100 g / m2to 5,000 g / m2.

11. A fiber-reinforced tape comprising: a thermoplastic resin; and a plurality of unidirectional continuous fiber yams embedded in the thermoplastic resin, wherein the plurality of unidirectional continuous fiber yarns comprises a first twisted fiber yarn and a second twisted fiber yam, and the first twisted fiber yarn and the second twisted fiber yarn have a different number of twists per meter in the length direction.

12. The fiber-reinforced tape of claim 11, wherein the first twisted fiber yarn is a carbon fiber yam.

13. The fiber-reinforced tape of any one of claims 11-12, wherein the second twisted fiber yarn comprises at least one of a glass fiber yarn, aramid fiber yarn, basalt fiber yam, an ultra high molecular weight polyethylene fiber yam, a liquid crystal polymer fiber yam, a poly(p- phenylene-2,6-benzobisoxazole) fiber yarn, a cellulose fiber yam, a rayon yarn, or a combination thereof.

14. The fiber-reinforced tape of any one of claims 11-12, wherein the elongation at break of the first twisted fiber yarn is substantially the same as the second twisted fiber yam.

15. The fiber-reinforced tape of any one of claims 11 -12, wherein the elongation at break of the first twisted fiber yarn is within 10% of the second twisted fiber yam.

16. A composite comprising two or more layers of the fiber-reinforced tape of any of the preceding claims.

17. The composite of claim 16, wherein the two or more layers of the fiber-reinforced tape comprises at least two layers of layers of the fiber-reinforced tape that are adhered to one another through the thermoplastic resin.

18. The composite of claim 16, wherein the composite comprises a first layer of fiber- reinforced tape in which the plurality of unidirectional continuous fiber yarns are oriented in a first direction and a second layer of fiber-reinforced tape in which the plurality of unidirectional continuous fiber yarns are oriented at an angle greater than 0° and less than or equal to 90° with reference to the plurality of unidirectional continuous fiber yarns in the first layer of fiber- reinforced tape.

19. The composite of claim 16, wherein the two or more layers of the fiber-reinforced tape comprises a first layer of the fiber-reinforced tape in which the plurality of unidirectional continuous fiber yarns are oriented in a first direction and a second layer of the fiber-reinforced tape having the plurality of unidirectional continuous fiber yams oriented at an angle of about 90° with reference to the plurality of unidirectional continuous fiber yarns in the first layer of the fiber-reinforced tape.

20. The composite of claim 16, wherein the composite has a flexural strength in a range of 1 MPa to 50 MPa.

21. The composite of claim 16, wherein the composite has a flexural modulus in a range of 0.1 GPa tol5 GPa.

22. A pipe comprising: a reinforcing layer and an outer jacket; wherein the reinforcing layer includes at least one fiber-reinforced tape of any one of the preceding claims.

23. The pipe of claim 22, wherein the fiber-reinforced tape is helically wrapped along a longitudinal direction of the pipe.

Images