Patent Publication Number: US-2016243802-A1

Title: Method and apparatus for making sheets of composite material

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of and claims the benefit of U.S. non-provisional divisional application Ser. No. 14/318,924 (now U.S. Pat. No.), which claims the benefit of U.S. non-provisional application Ser. No. 13/372,786 (now U.S. Pat. No. 8,763,668), filed on Feb. 14, 2012, which claims the benefit of U.S. non-provisional application Ser. No. 12/410,556, filed Mar. 25, 2009 (now U.S. Pat. No. 8,201,608), which claims the benefit of U.S. provisional application No. 61/039,556, filed Mar. 26, 2008. The contents of each application is incorporated herein by reference its entirety. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to methods for making sheets of composite materials, including composite laminate materials. 
     BACKGROUND 
     Sheets of composite materials that contain fibers in a thermoplastic resin matrix are useful as plies in the manufacture of composite laminate panels. The fibers are disposed in a polymeric matrix material to form a composite sheet. Various methods are known in the art by which the fibers in a sheet of composite material may be disposed in, and encapsulated by, the polymeric matrix material, including, for example, a doctor blade process, lamination, pultrusion, extrusion, etc. The fibers may be longitudinally oriented (that is, they are aligned with each other), and continuous along the length of the ply. The fibers can also be chopped and longitudinally oriented relative to one another. A sheet of composite material may be characterized as “unidirectional” in reference to the generally uniform longitudinal orientation of the fibers therein. 
     The width of a composite material sheet has typically been limited based on such factors as difficulty in controlling fiber distribution, as well as the width of traditionally used processing machinery. In addition, composite laminates include multiple plies that when stacked on top of one another can cause the fibers in different plies to have different angular orientations relative to one another. Composite laminates are generally assembled in discrete processes, by stacking individual plies of composite material with fibers in cross-wise relation to each other, and bonding the stack into a single sheet. 
     SUMMARY OF THE INVENTION 
     The present invention resides in one aspect in an apparatus for producing a composite laminate. The apparatus includes a first unwind station that includes at least one roll support assembly for rotatably supporting a roll of composite material. A tacking station is located downstream of the first unwind station and defines a tacking surface. A heating station is positioned downstream of the tacking station for heating the composite material fed from the roll in response to the composite material moving past the heater. The apparatus also includes a processing station including at least one calender roll assembly positioned downstream of the heating station. 
     The invention resides in another aspect in a method for making a composite laminate by positioning a plurality of lengths of composite material in adjacent relation to each other. The lengths of composite material are tacked together and the lengths of composite material are heated. The heated lengths of composite material are passed through a calender roll assembly to yield a composite laminate; and the composite laminate is collected. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of an apparatus for practicing the method of manufacture as described herein according to one embodiment of the present invention; 
         FIG. 2A  is a perspective view of one embodiment of an unwind station of the apparatus of  FIG. 1 ; 
         FIG. 2B  is a perspective view of a support roller assembly of the unwind station of  FIG. 2A ; 
         FIG. 2C  is a perspective view of a material guide assembly of the unwind station of  FIG. 2A   
         FIG. 3  is a perspective view of a tacking station with an optional second ply station in the apparatus of  FIG. 1 ; 
         FIG. 3A  is a perspective view of the tacking station of  FIG. 3  with first ply composite materials and a cross-ply composite material for tacking thereon. 
         FIG. 4  is a schematic perspective view of an oven station in the apparatus of  FIG. 1 ; 
         FIG. 5A  is an elevation view of one or more processing modules of the apparatus of  FIG. 1 ; 
         FIG. 5B  is a perspective view of a heated calender roll assembly of the one or more processing modules of  FIG. 5A ; 
         FIG. 5C  is an exploded perspective view of a roll oven for the heated calender roll assembly of the of one or more processing modules of  FIG. 5A ; 
         FIG. 5D  is a perspective view of a cooled calender roll assembly of the of one or more processing modules of  FIG. 5A ; 
         FIG. 6  is a perspective view of the uptake station of the apparatus of  FIG. 1 ; and 
         FIG. 7  is a flowchart of a method according to one embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     One embodiment of an apparatus for producing composite material, indicated generally at  10  in  FIG. 1 , includes an unwind station  12  where composite material can be fed or unwound from rolls of composite material for further processing by the apparatus  10 . There is a tacking station  14  adjacent to the unwind station, where additional layers of composite material can be tacked onto the composite material being unwound from the unwind station  12 . These additional layers can be configured so that the fibers forming part of the additional layers of composite material can be oriented at different angles relative to the fibers in the composite material being unwound from the unwind station  12 . However, the invention is not limited in this regard, as the fibers forming part of the additional layers can also be oriented substantially parallel to the fibers forming part of the composite being unwound from the unwind station  12 . The apparatus  10  includes an optional second unwind station  16  adjacent to the tacking station, where at least one additional layer of composite material can be unwound from rolls of composite material thereon. These layers can be unwound on top of the composite material unwound from the first unwind station  12  and any additional layers added at the tacking station  14 . There is a heating station  18  downstream from the tacking station  14 , where layers of composite material are heated so that they can bond to one another. There is also a processing station  20  downstream from the heating station  18 . The processing station  20  includes at least one calender roll assembly, as explained in greater detail below. An uptake station  22  is positioned downstream of the processing station  20  for winding composite material laminate thereon. The overall progress of composite material from the unwind station  12  to the uptake station  22  is referred to herein as “the process direction,” indicated by the arrows in  FIG. 1 . The terms “upstream” and “downstream” are sometimes used herein to refer to directions or positions relative to the process direction (“downstream” referring to a direction consonant with the process direction). 
     As shown in  FIG. 2A , the unwind station  12  includes an unwind frame  24  on which are mounted five similarly configured roll support assemblies, one of which is indicated at  26 . While the unwind station  12  has five roll support assemblies  26 , the present invention is not limited in this regard as fewer than, or more than, five roll support assemblies can form part of the unwind station without departing from the broader aspects of the present invention. The roll support assembly  26 , like the other roll support assemblies shown in  FIG. 2A , includes a support roller assembly  28  (also seen in  FIG. 2B ) and an associated material guide assembly  30  (also seen in  FIG. 2C ). The support roller assembly  28  comprises a support roller  32  rotatably coupled to a pedestal  34 , the pedestal being mounted to the unwind frame  24 . Each support roller  32  is configured to carry a roll of composite material thereon, as indicated by the rolls of composite material  36   a,    36   b,    36   c  in  FIG. 2A . A locking cap  38  is removably mounted to the support roller  32  to removably retain a roll of composite material thereon. The locking cap  38  can be threaded onto the support roller  32 , however, the present invention is not limited in this regard as the locking cap can be retained on the support roller in other manners known to those skilled in the pertinent art to which the present invention pertains. For example, the locking cap  38  could be bolted onto the support roller  32  or retained thereon via a snap ring. The support roller assembly  28  may include a support roller drive mechanism (not shown) or a support roller braking mechanism (not shown) to accelerate or retard the unwinding of the roll of composite material  36   a  on the support roller  32  to vary or adjust the amount of tension in the composite material as it is unwound from the roll. 
     Each material guide assembly  30  includes a pair of upstanding roller mounts  40 ,  42  that are secured to the unwind frame  24 . Each material guide assembly  30  further includes a first roller  44  interposed between, and rotatably coupled to, the upstanding roller mounts  40 ,  42 , and a second roller  46  interposed between and also rotatably coupled to the upstanding roller mounts. The first roller  44  and the second roller  46  cooperate to define a nip indicated at  48  between them through which composite material being fed from the associated support roller assembly  28  passes. The first roller  44  may be vertically slidable relative to the upstanding roller mounts  40 ,  42  by an adjustment mechanism  50  that serves to vary and/or adjust the pressure on composite material  36   a  in the nip and/or the tension in the composite material  36   a,  etc. and/or the rate at which the composite material is drawn from the associated support roll assembly  28 . The adjustment mechanism  50  can take the form of a pneumatic or hydraulic cylinder, a ball screw, a stepper motor or other mechanical actuator. However, the present invention is not limited in this regard as numerous other adjustment mechanisms that would be known to one of ordinary skill in the art to which the invention pertains may be employed. The material guide assembly  30  serves to orient and direct the composite material  36   a,  etc. being drawn from the associated support roller assembly  28 . 
     Each material guide assembly  30  may comprise a brake mechanism (not shown) and/or a drive mechanism (not shown). The brake mechanism would impart resistance to the rotation of the first roller  44 , so that a desired tension can be maintained in the composite material  36   a  as it is pulled through the nip indicated at  48 . On the other hand, a material guide drive mechanism may drive the first roller  44  to facilitate passage of the composite material  36   a  through the nip indicated at  48 . In this way, the adjustment mechanism  50  may alleviate resistance to the advancement of the composite material  36   a  through the nip indicated at  48 . Since the rotational inertia of a roll of composite material  36   a  on a support roller  32  varies as material is drawn from the roll, the adjustment mechanism  50  may be adjusted during operation of the apparatus  10  to maintain an appropriate tension in the composite material  36   a.    
     The five roll support assemblies  26  are positioned on the unwind frame  24  so that when lengths of composite material  36   a,  etc. are drawn from each roll, the lengths will pass through a web aperture  52  in the unwind frame  24  and emerge from beneath the unwind frame  24  in side-by-side arrangement to define a web  54  ( FIG. 2A ,  FIG. 4 ) that spans a width W defined by the number of rolls of composite material, the width W being wider than any one of the rolls of composite material. As will be explained in detail below, the web  54  provides at least a lengthwise first layer for a composite laminate  200 . 
     The tacking station  14  is located downstream from the unwind station  12  and includes a tacking platform  56  mounted on a tacking frame  58 . The tacking frame  58  in the illustrated embodiment defines a width that is approximately equivalent to the width of the unwind frame  24 . The tacking platform  56  defines a substantially planar tacking surface  56   a  on which adjacent lengths of composite material  36   a,    36   b,  etc. are disposed and tacked together to form a first layer of the composite material  200 , e.g., by disposing a second layer of composite material onto the first layer of composite material  36   a,    36   b,  etc. Depending on the type of composite material  36   a,  etc. and the fiber orientation therein, the second layer of composite material can be tacked either lengthwise or in a cross ply or other configuration. 
     In one embodiment, the composite material  36   a,    36   b,  etc. is tacked together by laying a cross ply  60  of composite material onto the composite material  36   a,    36   b,  etc. The cross ply  60  overlaps at least two adjacent composite materials  36   a,    36   b  and preferably extends across the entire width W of the web  54 . The cross ply  60  is tacked onto the composite material  36   a,    36   b,  etc. to form a web  54 . Tacking may be accomplished using heat guns, ultrasonic welding tools, adhesives, or the like, while the web  54  is moving through the apparatus  10 . Tacking is a relatively quick and easy way of securing adjacent and/or layered sheets of composite material in the desired position for being bonded together. 
     The cross ply  60  may be a unidirectional sheet, i.e., the fibers therein may be mutually aligned. In a particular embodiment, the fibers in the cross ply  60  are disposed in transverse relation to the fibers in the composite material  36   a  in which case the cross ply  60  may be referred to as a cross-ply sheet and the resulting composite laminate  200  is referred to as a cross-ply laminate. The cross ply sheet may be disposed at any angle relative to the fibers in the composite material  36   a,    36   b,  etc. 
     A cross ply  60  has a limited width  60 w in the process direction. In one embodiment, a plurality of cross plies  60  are disposed in adjacent relation to each other on the layers of the composite material  36   a,    36   b,  etc., to provide a consistent second ply for composite laminate  200 . 
     In one embodiment, an industrial robot may be employed to place cross plies  60  on the composite material  36   a,    36   b,  etc. and, optionally, to tack the cross plies  60  thereon. Such a robot may be provided with a supply of cross ply material, e.g., in roll form or as a stack of pre-cut sheets. The robot may be equipped to place the cross ply material onto the web  54 , e.g., by drawing a length of the cross ply material from the supply roll and cutting the cross ply material to the desired length, or by handling a pre-cut sheet. The robot may be equipped with a tacking arm that includes a heat gun, sonic welding horn, or any other suitable tacking device, and that may tack the cross ply material to the web  54  and tack the composite material  36   a,    36   b,  etc. together. The robot may be configured to draw or place the cross ply material orthogonally across the web  54  or at any other desired angle. 
     The optional second unwind station  16  is positioned downstream from, and above, the tacking station  14  and includes roll support assemblies  62  where additional rolls of composite material may be disposed. The second unwind station  16  has generally the same configuration as the first unwind station  12  to enable the second unwind station  16  to provide a web of composite material that spans a width approximately equal to width W, i.e., the second unwind station  16  has roll support assemblies  62  positioned to correspond to the positions of the roll support assemblies  26  etc. of the first unwind station  12 . The second unwind station  16  is configured to permit the web  54  to pass beneath it and to allow an additional lengthwise layer of composite material from the second unwind station  16  to be added onto the web  54 . In this way, the second unwind station  16  facilitates providing a second lengthwise layer of composite material for the composite laminate  200 . While a second unwind station  16  has been shown and described for the apparatus  10 , the present invention is not limited in this regard, and in other embodiments, an apparatus for making composite laminate may not have a second unwind station. In still other embodiments, an apparatus for making composite laminate may include more than two unwind stations, to enable the apparatus to produce a composite laminate having more than two lengthwise layers of composite material. 
     As shown in  FIG. 4 , one embodiment of a heating station  18  includes an oven  64  that has an entrance (not shown) that is adapted to receive the web  54  of composite material, and an exit  66  to allow the web  54  to move through the oven. The oven  64 , which may include a convection oven and/or any other suitable heating element such as an electric radiant heating element, an infrared heating element, electric heaters, hot oil heaters, air impingement heaters, combinations thereof, and the like for heating the web. The oven  64  has a cover  68  that is movable between a raised position and a lowered position via an actuator  70  such as, but not limited to, a hydraulic or pneumatic cylinder, a lead screw, a motor and the like. 
     The processing station  20  is located downstream from the heating station  18 . In one embodiment, as seen in  FIG. 5A , the processing station  20  comprises calendar roll assemblies  72  and  74 . Each calender roll assembly  72 ,  74  includes a frame  80  which supports two calender rolls  76  and  78 . A drive mechanism  82  for each roll includes a drive motor  82   a  that is coupled to the calender roll  76  or  78  via a drive belt  82   b.  While a belt drive has been shown and described, the present invention is not limited in this regard as other types of drives, such as a direct drive, or motor and gear reducer combination can be utilized. One or both of the calender rolls  76  and  78  in a calender roll assembly  72 ,  74  may be equipped with a rotary union that permits the flow of a thermal transfer fluid (e.g., oil or water) through the roll, to heat or cool the roll during use, as desired. 
     As best seen in  FIG. 5B , a heated calender roll assembly  72  comprises calender rolls  76  and  78  which cooperate to define a nip therebetween, and two roll ovens,  84  and  86 , for the heating calender roll  78 . Roll oven  84  heats a portion of the calender roll  78  and the second roll oven  86  is provided so that the calender roll is heated over its entire length, however, the invention is not limited in this regard, and in other embodiments, a single roll oven may heat the entire length of a calender roll, or only a selected portion of a calender roll may be heated. The calender roll assembly  72  includes a support follower  88  mounted and supported on calender roll assembly  72  so that it bears centrally on calender roll  76 . Likewise, a support follower (not shown) is mounted to bear centrally on calender roll  78 . The support followers  88  inhibit the calendar rollers from bowing away from each other in a central region. As seen in  FIG. 5C , the roll oven  86  comprises an electric radiant heating element  90  that is configured to conform to the curvature of the calender roll  78 . The roll oven  84  ( FIG. 5B ) is configured similarly to the roll oven  86 . Alternatively, or in addition, one or both of the calender rolls  76  and  78  may be hollow and may define a flow path for the ingress and egress of a thermal transfer fluid therethrough, the thermal transfer fluid being supplied and withdrawn to and from a fluid supply. The roll  76  and/or the roll  78  may be equipped with a rotary union coupled to the roll through which hot thermal transfer fluid is flowed through the roll to provide heat. 
       FIG. 5D  provides a perspective view of an unheated calender roll assembly  74 , which is configured similarly to calender roll assembly  72 , except for the omission of the roll ovens  84  and  86 . In the absence of roll oven  84  and roll oven  86 , it can be seen that the calender roll assembly  74  includes two support followers  88  to bear centrally on the calender rolls  76 ,  78 , as in calender roll assembly  72 . The calender roll  78  is hollow and defines a flow path for the ingress and egress of a thermal transfer fluid therethrough, the thermal transfer fluid being supplied and withdrawn to and from a fluid supply. In the illustrated embodiment, the roll  78  is equipped with a rotary union  92  coupled to the roll and through which a thermal transfer fluid is flowed through the roll to draw heat from the web  54  in contact therewith. If necessary, the rotary union  92  can be used to provide a heating fluid to heat the calender roll  78 . 
     The processing station  20  is shown in  FIG. 5A  as having four calender roll assemblies  72  and  74 , however, the invention is not limited in this regard, and in other embodiments a processing station  20  may include more than four or fewer than four calender roll assemblies, and may or may not have a cooling calender roll assembly and/or a heated calender roll assembly. For example, in one embodiment, rather than providing a cooled calender roll assembly, it may be sufficient to cool the web  54  by using a fan to blow cool air onto the web before the web passes to the uptake station  22 , and/or by providing one or more unheated calender roll assemblies following the heated calender roll assembly  72 , with the unheated calender roll assembly being spaced from the heated calender roll assembly  72  by a distance sufficient to allow heat to dissipate from the web  54  into the ambient air. 
     As shown in  FIG. 6 , the uptake station  22  comprises an uptake roll  96  positioned on an uptake frame  94 . The uptake station  22  includes a motorized drive (not shown) for the uptake roll  96 , to maintain an appropriate tension in the web  54 . The motorized drive for the uptake roll  96  allows the uptake roll to collect the composite laminate  200  finished product from the processing station  20 . 
     The various parts of the above-described apparatus  10  can be re-arranged as desired from the layout shown in  FIG. 1 , for example, to change the sequence in which material moving through the apparatus  10  in the process direction encounters the various stations, to omit stations that are not needed for a particular process, or to add additional stations between the unwind station  12  and the uptake station  22 . In addition, the components of the various stations are movable and can be re-arranged within their respective stations. For example, one or more roll support assemblies  26  may be added to, or removed from, the unwind station  12 , as desired. In addition, the roll support assemblies  26  may be re-arranged on the unwind frame  24  to provide varying degrees of overlap from adjacent composite material  36   a,    36   b,  etc., in the web  54  and/or to provide a web  54  of various desired widths. Likewise, the calender roll assemblies  72 ,  74  of the processing station  20  are movable on, and removable from, the calender roll frame  80 . Accordingly, the number, type, sequence and/or spacing of calender roll assemblies in the processing station  20  can be changed to accommodate the characteristics desired in the composite laminate  200  end product. For one product or process, a single calender roll assembly  72  or  74  might be sufficient; for another, three or four calender roll assemblies (or more) may be employed. In addition, the calender roll assemblies  72 ,  74  may be rearranged to provide any desired sequence of heated calender roll assemblies and cooling calender roll assemblies: heat, then cool; cool, heat, then cool; heat, cool, heat again; heat, cool, heat again, then cool; etc. Such flexibility in the apparatus allows for flexibility in the process employed to make various products. 
     The apparatus  10  may include a process controller (not shown) that communicates with the principal control mechanisms of the apparatus. In this way, the process controller provides a centralized point where an operator can control one or more aspects of the operation of the apparatus, such as the speed of the web  54  through the apparatus, the tension in the web, the pressure applied at various nips, the temperature of the heating station  18 , the amount of heat supplied by heated calender roll assemblies  72 , the operation of the industrial robot for applying the cross ply and/or tacking the web  54 , etc. 
     In one embodiment, the apparatus  10  can be used to carry out a method indicated generally at  100  in  FIG. 7  for making a composite laminate  200 . The method  100  begins with a first step  102  of providing lengths of composite material, e.g., from rolls of composite material  36   a,    36   b,  etc., mounted on the roll support assemblies  26  of the unwind station  12 . The lengths of composite material  36   a  etc. are drawn and arranged into a web  54  that extends to the tacking station  14 . In a tacking step  104 , the composite material  36   a  etc. is tacked together at the tacking station  14  to form the web  54 , for example, with the use of the cross ply  60 . 
     In an optional layering step  106 , additional lengths of composite material may be added to the web  54 . For example, additional rolls composite material may be disposed on the second unwind station  16  and the additional composite material may be unwound from the second unwind station  16  and applied onto the first ply composite material  36   a,  etc. and onto the cross ply  60 . In this case, the method  100  can yield a composite laminate  200  ( FIG. 6 ) which includes two continuous plies (one each from unwind stations  12  and  16 ) with a cross-ply  60  between them. 
     After the tacking step  104 , and after optionally applying additional layers of composite material on the web  54  in step  106 , the web  54  is subjected to a heating step  108  to help the lengths of composite material  36   a  etc. and any cross ply  60  thereon to bond together. 
     For this purpose, the web  54  passes to the heating station  18 , where the adjacent first ply composite material  36   a  etc. are heated to soften the polymeric material therein so that the various sheets can be bonded to one another. After the heating step  108 , the web  54  is subjected to a processing step  110  in which the lengths of composite material  36   a  etc. are formed into a composite laminate  200  that can be collected. For example, in one processing step  110 , the web  54  passes to the processing station  20 , where the material is subjected to pressure and, optionally, heating and/or cooling in one or more calender roll assemblies  72  and/or  74 . The heat and/or pressure of the calender roll assemblies  72  and/or  74  causes the adjacent composite material  36   a,    36   b,  etc. (and any other composite materials thereon) to bond together. When adjacent composite material  36   a,    36   b,  etc. comprise thermoplastic matrix materials, the heat and/or pressure of the calender roll assemblies  72  and/or  74  may be sufficient to cause the matrix materials. However, if one or both of the adjacent composite materials comprise thermosetting matrix materials, it may be desirable to provide adhesive or other additional means as are known to one of ordinary skill in the art, to bond the composite materials together. The web  54  is cooled as part of the processing step  110 , and in a collection step  112 , the composite laminate  200  product is collected at the uptake station  22  onto an uptake roll  96 . The cooling that occurs in the processing step  110  permits the web  54  to collected, e.g., wound on a roll, as the composite laminate  200  without bonding adjacent windings of the composite laminate onto each other. 
     In the embodiment of  FIGS. 1 and 5A-5D , the web  54  advances in the process direction through the heated calender roll assemblies  72  and then through the cooling calender roll assemblies  74 . The heated calender roll assemblies  72  heat the composite materials so that adjacent composite materials bond together. Both calender roll assemblies  72  and  74  also compress the composite materials together to enhance the bonding process. The cooling calender roll assemblies  74  then remove heat from the web  54  so that adjacent layers of the composite laminate  200  will not merge into each other at ambient temperatures. In this way, storage and handling of the composite laminate  200  is facilitated. For example, the composite laminate  200  may be collected onto an uptake roll  96  at the uptake station  22  without bonding adjacent windings onto each other. 
     By providing rolls of composite material  36   a  etc. of sufficient length so that product sheet can be wound onto an uptake roll  96  as composite material  200  is still being unwound from the unwind station  12 , the process and apparatus described herein can be described as a “continuous” process. 
     Various types of fibers may be used in a composite material. Example fibers include E-glass and S-glass fibers. E-glass is a low alkali borosilicate glass with good electrical and mechanical properties and good chemical resistance. This type of glass is the most widely used in fibers for reinforcing plastics. Its high resistivity makes E-glass suitable for electrical composite laminates. The designation “E” is for electrical. 
     S-glass is the higher strength and higher cost material relative to E-glass. S-glass is a magnesia-alumina-silicate glass for aerospace applications with high tensile strength. Originally, “S” stood for high strength. Both E-glass and S-glass are preferred fibers in this invention. 
     E-glass fiber may be incorporated in the composite in a wide range of fiber weights and thermoplastic polymer matrix material. The E-glass may range from about 10 to about 40 ounces per square yard (oz./sq.yd.), more preferably 19 to 30 and most preferably 21.4 to 28.4 oz./sq.yd. of reinforcement. 
     The quantity of S-glass or E-glass fiber in a composite material ply may optionally accommodate about 40 to about 90 weight percent (wt %) thermoplastic matrix, more preferably about 50 to about 85 wt % and most preferably, about 60 to about 80 wt % thermoplastic matrix in the ply, based on the combined weight of thermoplastic matrix plus fiber. 
     Other fibers may also be incorporated, preferably in combination with E-glass and/or S-glass, but optionally instead of E- and/or S-glass. Such other fibers include ECR, A and C glass, as well as other glass fibers; fibers formed from quartz, magnesia alumuninosilicate, non-alkaline aluminoborosilicate, soda borosilicate, soda silicate, soda lime-aluminosilicate, lead silicate, non-alkaline lead boroalumina, non-alkaline barium boroalumina, non-alkaline zinc boroalumina, non-alkaline iron aluminosilicate, cadmium borate, alumina fibers, asbestos, boron, silicone carbide, graphite and carbon such as those derived from the carbonization of polyethylene, polyvinylalcohol, saran, aramid, polyamide, polybenzimidazole, polyoxadiazole, polyphenylene, PPR, petroleum and coal pitches (isotropic), mesophase pitch, cellulose and polyacrylonitrile, ceramic fibers, metal fibers as for example steel, aluminum metal alloys, and the like. 
     A preferred organic polymer fiber is formed from an aramid exemplified by Kevlar. Other preferred high performance, unidirectional fiber bundles generally have a tensile strength greater than 7 grams per denier. These bundled high-performance fibers may be more preferably any one of, or a combination of, aramid, extended chain ultra-high molecular weight polyethylene (UHMWPE), poly [p-phenylene-2,6-benzobisoxazole] (PBO), and poly[diimidazo pyridinylene (dihydroxy) phenylene] (M 5 ). The use of these very high tensile strength materials is particularly useful for making composite ballistic armor panels and similar applications requiring very high ballistic properties. 
     Still other fiber types known to those skilled in the particular art to which the present invention pertains can be substituted without departing from the broader aspects of the present invention. For example, Aramid fibers such as, inter alia, those marketed under the trade names Twaron, and Technora; basalt, carbon fibers such as those marketed under the trade names Toray, Fortafil and Zoltek; Liquid Crystal Polymer (LCP), such as, but not limited to LCP marketed under the trade name Vectran. Based on the foregoing, the present invention contemplates the use of organic, inorganic and metallic fibers either alone or in combination. 
     The composite plies of the present invention may optionally include fibers that are continuous, chopped, random, commingled and/or woven. In particular embodiments, composite plies as described herein may contain longitudinally oriented fibers to the substantial exclusion of non-longitudinally oriented fibers. 
     The polymeric matrix material may comprise a thermosetting polymer and/or a thermoplastic polymer. A thermoplastic polymer resin material that may be a high molecular weight thermoplastic polymer, including but not limited to, polypropylene, polyethylene, nylon, PEI (polyetherimide) and copolymers, more preferably, polypropylene and polyethylene. Thermoplastic loading by weight can vary widely depending on physical property requirements of the intended use of the product sheet. 
     A composite material may contain about 60 to about 10 wt % thermoplastic matrix, more preferably about 50 to about 15 wt % and most preferably, about 40 to about 20 wt % of thermoplastic matrix material, by weight of thermoplastic matrix material plus fibers. 
     The terms “first,” “second,” and the like, herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. In addition, the terms “a” and “an” herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. 
     Although the invention has been described with reference to particular embodiments thereof, it will be understood by one of ordinary skill in the art, upon a reading and understanding of the foregoing disclosure, that numerous variations and alterations to the disclosed embodiments will fall within the spirit and scope of this invention and of the appended claims.