United States Patent [191
`Tailor et al.
`
`[54] FABRIC-FACED THERMOPLASTIC
`COMPOSITE PANEL
`
`[76]
`
`Inventors: Dilip K. Tailor, 22 Torrance Woods,
`Brampton, Ontario L6Y 2T2; Mark F.
`Lang, 437 Watson Avenue, Oakville,
`Ontario L6J 3WI; Paul S. Hruska, 525
`Meadows Blvd. #23, Mississauga,
`Ontario L4Z 1H2; Kevin J.
`McConnell, 25 Nash Road North #108,
`Hamilton, Ontario L8M 2P4, all of
`Canada
`
`[21] Appl. No.: 196,925
`
`[22] Filed:
`
`Feb. 15, 1994
`
`[51]
`
`Int. Cl.6
`
`................................ B32B 5/04; B32B 5/12;
`B32B 5/28
`[52] U.S. Cl . ..................... 428/110; 12/142 N; 12/146 D;
`12/146 M; 12/146 S; 36/71; 36/145; 36/154;
`36/DIG. 2; 156/176; 428/35.7; 428/36.1;
`428/36.2; 428/111; 428/195; 428/196; 428/226;
`428/230; 428/231; 428/232; 428/236; 428/238;
`428/239; 428/246; 428/294; 428/542.8
`
`I 1111111111111111 11111 111111111111111 IIIII IIIII IIIII 11111 lll111111111111111
`5,529,826
`Jun.25, 1996
`
`US005529826A
`[11] Patent Number:
`[45] Date of Patent:
`
`[58] Field of Search ..................................... 428/231, 232,
`428/236, 238, 196, 36.1, 542.8, 110, 111,
`226, 230, 239, 246, 294; 156/176
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`3/1987 Hannibal .
`4,651,445
`4,778,717 10/1988 Fitchmun.
`5,082,701
`1/1992 Craven et al ..
`
`Primary Examiner-James C. Cannon
`Attorney, Agent, or Firm-Duane, Morris, & Heckscher
`
`[57]
`
`ABSTRACT
`
`Polymer matrix composite materials containing a thermo(cid:173)
`plastic composite core bonded integrally with a fabric layer
`are provided. The fabric layer has a greater elasticity than the
`core, so that the fabric layer can conform smoothly to the
`core during thermoforming. This improvement has been
`demonstrated to improve aesthetic appearance and nearly
`eliminate wrinkling and distortion of the fabric layer when
`compared to conventional composite materials.
`
`23 Claims, 3 Drawing Sheets
`
`40
`16
`-----i8
`":A.---16
`,,-----~/8
`40
`
`EX1066
`Yita v. MacNeil
`IPR2020-01139
`
`

`

`U.S. Patent
`
`Jun.25, 1996
`
`Sheet 1 of 3
`
`5,529,826
`
`FIG. 1
`
`FIG. 2
`
`/0
`
`FIG. 3
`
`

`

`U.S. Patent
`
`Jun.25, 1996
`
`Sheet 2 of 3
`
`5,529,826
`
`40
`
`50
`
`I
`
`I
`
`FIG. 4
`
`FIG. 5
`
`40
`16
`i8
`,.._.,___ __ /6
`
`.-.:-ni---/8
`40
`
`100
`
`FIG. 6
`
`

`

`U.S. Patent
`
`Jun. 25, 1996
`
`Sheet 3 of 3
`
`5,529,826
`
`FIG. 7a
`
`FIG. 7b
`
`FIG. 7c
`
`FIG. 7d
`
`

`

`5,529,826
`
`1
`FABRIC-FACED THERMOPLASTIC
`COMPOSITE PANEL
`
`FIELD OF THE INVENTION
`
`This invention relates to polymer matrix composites, and
`more particularly, to thermoplastic composite materials that
`include a fabric facing for improving aesthetics and prop(cid:173)
`erties.
`
`BACKGROUND OF THE INVENTION
`
`5
`
`25
`
`2
`ingly, special methods have been developed to produce
`unidirectional thermoplastic composites with good wet-out
`and uniform fiber dispersion.
`One of these methods involves passing continuous fibers
`through a fluidized bed of thermoplastic resin powder. The
`powder penetrates into the web of the fibers, and the coated
`fibers are then heated and formed into a tape configuration.
`Alternatively, the fibers can be extruded through a melt of
`thermoplastic polymer, followed by shaping the coated fiber
`10 bundle. Still other methods of impregnating these fibers are
`to pass them through a solution in which a thermoplastic
`them
`polymer powder is suspended, or sandwiching
`between films of polymer. Other methods included passing
`the fiber through solvated resins, or through liquid partially
`15 polymerized or unpolymerized resins. The unidirectional
`tape can also be made using fibers of resin commingled with
`reinforcing fibers.
`The end result of these impregnation methods is basically
`the same. A tape is produced in which there are continuous
`20 fibers in the axial or longitudinal direction, and these fibers
`are encapsulated within a given thermoplastic resin.
`Fabrication of finished parts from fiber-reinforced ther(cid:173)
`moplastic composite unidirectional tapes has followed the
`especially labor-intensive process developed for fiber-rein-
`forced thermoset composite unidirectional tapes. That is,
`these tapes are typically laid in successive laminated layers
`at predetermined angles to obtain the desired structural
`properties in a finished format of greater dimensions than the
`individual tapes. The tapes can be processed by hand, or
`30 with complicated, and often expensive, automatic tape lay(cid:173)
`ing machinery. Unlike fiber-reinforced thermoset tapes,
`which are more suitable for fabrication by these methods
`because they remain tacky until cured and can be held in a
`set position, lay-up fiber-reinforced thermoplastic tapes usu-
`35 ally require that each tape be tacked, welded, or stitched in
`position before laying the next tape. These thermoplastic
`composite tapes can be difficult to mold since they are also
`known to be "stiff and boardy".
`In order to produce a panel from these thermoplastic
`unidirectional tapes, techniques have been developed to hold
`them together prior to molding. One method disclosed in
`U.S. Pat. No. 5,082,701 suggests that the unidirectional
`fiber-reinforced thermoplastic tapes can be interlaced in an
`over-and-under relationship in a 0°/90° configuration. The
`interlaced material is then subjected to heat and pressure in
`single or multiple layers to form an integral panel. Alterna(cid:173)
`tively, the tapes can be placed adjacently and seamed
`side-to-side, to produce a wide unidirectional sheet. In
`another method, the commingled resin/reinforcement fibers
`are woven into a fabric, and layers of this fabric are
`consolidated into a laminate by pressing or thermoforming.
`Laminates can also be produced by placing films of resin
`between layers of reinforcement fabric (woven or unwoven)
`and impregnating the fabric with the film by heat and
`pressure.
`Preferably, the resulting sheets are placed on top of one
`another and then laminated together in a compression mold(cid:173)
`ing press. Additional polymeric films can be placed on top
`of the initial assembly, particularly over the woven sheets, to
`fill up the voids due to undulations of the woven pattern.
`While such panels have successfully tackled the wet-out
`and uniform dispersion problems associated with impreg(cid:173)
`nating fiber bundles with thermoplastic resin, there have
`been several drawbacks to these fabrication methods.
`When the panels are thermoformed to extreme contours,
`as in deep drawing, there is a tendency for the panels to
`
`Unreinforced engineering thermoplastics typically have
`tensile strengths that range from 8,000 to 15,000 psi. One
`popular engineering plastic, nylon 6/6, has a tensile strength
`of 12,000 psi and a tensile modulus of 500,000 psi. How(cid:173)
`ever, to compete with metals in applications ranging from
`automobiles to tennis rackets, plastics typically need to be
`reinforced to improve their mechanical properties.
`Reinforcing thermoplastics and thermosets dramatically
`increases their strength. For example, short glass fibers at 30
`wt. % loading can boost the tensile strength of engineering
`plastics by a factor of about two. Some advanced polymer(cid:173)
`matrix composites (PMCs) have higher specific strength and
`stiffness than metals. Advanced composites reinforced with
`high modulus carbon fiber, for example, are known to have
`a tensile modulus of about 12.0 million psi and a tensile
`strength of 165,000 psi, but are much lighter than aluminum.
`Polymer matrix composites are available in fiber-rein(cid:173)
`forced thermoset matrixes or fiber-reinforced thermoplastic
`matrixes. The thermoset matrixes typically include epoxy or
`polyester resins which harden through a catalytic process.
`The primary disadvantage of these systems has been that the
`resins include a hardener/catalyst to cure them, and this
`results in a limited shelf-life which may require refrigera(cid:173)
`tion. This irreversible catalytic process requires a long
`curing cycle prior to hardening, and when these resins have
`finally set, they cannot later be thermoformed into a different
`configuration. Thermosets are also known to exhibit low
`ductility.
`Because of their inherently faster processing time-no
`time-consuming curing or autoclaving-thermoplastic
`matrix composites are beginning to replace conventional
`thermoset composites. In the aircraft and aerospace sectors,
`current development work in thermoplastics is showing
`promising results for typical laminated structures, filament
`winding, and pultrusion. Several thermoplastic composite
`components have flown on United States Naval and Air
`Force jets in demonstration programs, and initial applica(cid:173)
`tions have included various access doors and outer wing
`panels on the Navy's F-18 fighter.
`In order to obtain the maximum performance of thermo(cid:173)
`plastic composites in a given direction, continuous oriented
`fibers are lined in that direction in the composite. To improve
`the overall strength of the composite in all directions, these
`fibers can be alternated in succeeding layers to obtain
`multi-axial orientation and performance. The maximum
`performance of a thermoplastic composite is realized when
`each of the fiber filaments is wetted out by the resin, and 60
`when these wetted filaments are uniformly dispersed in the
`composite' s cross-section.
`The wetting of fiber filaments with thermoset resins is
`very efficient, since these resins tend to be low viscosity
`liquids. Thermoplastic resins usually require heat to melt 65
`them, and even then, they form a highly viscous melt, which
`does not readily flow to wet out the fiber filaments. Accord-
`
`40
`
`45
`
`50
`
`55
`
`

`

`5,529,826
`
`4
`wrapped core material, employs a true solid composite with
`a homogeneous distribution of the fibers throughout its body,
`and which can be molded into a smooth finished article
`without distortion or wrinkling, while simultaneously retain-
`ing a high modulus and tensile strength. There is also a need
`for a thermoplastic composite material which can be pro(cid:173)
`vided with a greater degree of aesthetic appeal for consumer
`applications.
`SUMMARY OF THE INVENTION
`
`s
`
`3
`wrinkle rather than conform to produce smooth contours.
`This wrinkling occurs because the outside surface has con(cid:173)
`tinuous fibers which have little ductility, and they tend to
`distort and buckle when going over the contours in the die.
`In the case of a seamed-tape panel, the continuous unidi(cid:173)
`rectional fibers also have a tendency to bundle up and appear
`as longitudinal wrinkles when molding certain shapes.
`When such thermoplastic composite panels are subjected
`to flexing, the outermost unidirectional fibers on the top and
`bottom of the panels experience the maximum tensile and 10
`compressive stresses respectively while the fibers in the
`middle of the composite are stressed less, if at all. Since
`typical reinforcing fibers of carbon and glass have only
`about 1-4% elongation, the fibers on the top and bottom tend
`to fracture or buckle during static and dynamic loads. These 15
`fractures, along with the many seams and distortions in the
`fiber orientation and distribution can result in an outward
`appearance which can be generally unappealing, not to
`mention structurally defective.
`In consumer applications, such as athletic shoes and shoe
`orthotic in-soles, where aesthetic appeal is critical, the
`presence of colors or patterns which beautify the panel are
`required. While currently produced woven-tape panels pro(cid:173)
`vide some pattern derived from the type of weave, and some
`colors halve been produced using colored unidirectional
`tapes, there is a limit to the available designs, particularly
`with respect to the width of the tape that can be used. Use
`of narrow tapes, such as 5 mm in width could provide
`interesting patterns, but the processes become very cumber(cid:173)
`some and expensive, since large numbers of unwind creels
`would be necessary to produce a wide sheet. Also, if many
`colors are necessary, the process of feeding the warps and
`wefts in woven sheets of unidirectional tape becomes expen(cid:173)
`sive and difficult.
`In order to address the wrinkling and delarnination prob-
`lem associated with standard laminated thermoplastic com(cid:173)
`posite structures, some have chosen to limit the fiber content
`to no more than about 33 vol. % of the total volume of the
`composite. See Fitchmun, U.S. Pat. No. 4,778,717, which is
`hereby incorporated by reference. Fitchmun describes a 40
`composite having a thermoplastic core and fibrous layers
`adhered to the thermoplastic core, whereby the total fiber
`volume is less than 1/J of the total volume of the composite.
`He further teaches that fiber volume fractions greater than
`50% of the total volume "completely resist" molding into a 45
`desired shaped, and if molded, contribute to rippling and
`buckling of portions of the surface of the resulting molded
`structure. He suggests that the buckled portions result from
`the failure of the fibrous material to properly move relative
`to the core which produces a locking of the sheet material 50
`during molding. This locking can only be relieved, he states,
`by severe folds.
`Unfortunately, since Fitchmun does not teach a large
`enough loading of fiber reinforcement in his thermoplastic
`composites for many PMC applications,
`the
`typical 55
`improvements in modulus and tensile strength derived from
`greater fiber volume fractions are not obtainable with his
`composite. More importantly, Fitchmun teaches a composite
`structure in which the fiber reinforcement is only on the
`surface on each side of the plastic core. He uses the core of 60
`thermoplastic material between the two fabric layers to
`allow the two fabric layers to move independently of each
`other during thermoforming. He explains that the indepen(cid:173)
`dent freedom of movement enables the layers of fabric to be
`molded into complex shapes.
`Accordingly, there appears to be a need for a thermoplas(cid:173)
`tic composite material that, instead of employing a fabric-
`
`65
`
`35
`
`25
`
`Polymer matrix composites are provided by this invention
`which are suitable for thermoforming to form molded
`articles. These composite materials include a thermoplastic
`composite core and a fabric layer integrally bonded to the
`core. In order to minimize buckling and wrinkling of the
`fabric layer as it attempts to conform to the composite core
`during thermoforming, the fabric layer is provided with
`greater elasticity than the core so that it can stretch and
`conform smoothly to the core as it is shaped.
`The thermoformable thermoplastic composite materials
`20 of this invention overcome the problems cited above for
`conventional composites. Due to the inherent nature of the
`fabrics of this invention, there is some elasticity present in
`the fabric. The type of fibers used for these fabrics such as
`polyester and nylon, also have inherent elasticity, which
`facilitates their suitability for the molded applications. Pref(cid:173)
`erably, the elasticity is at least 5% greater than the elasticity
`of the composite core at a given load. During molding onto
`contours of a mold, this retained elasticity allows the fabric
`to conform smoothly without wrinkling or buckling prior to
`30 being fixed to the core by molten resin. The fabrics of this
`invention are capable of producing much smoother surfaces,
`than woven tapes of composite material which trap their
`fibers in the oriented state with impregnated resin. The fibers
`of the fabrics of this invention are free to adjust to defor(cid:173)
`mation pressures and, i.e. there is some "slackness" present
`in them prior to thermomolding.
`In more preferred embodiments of this invention, a ther(cid:173)
`moplastic composite core is provided which includes at least
`two laminated thermoplastic sheets including unidirectional
`fibers having a first and a second orientation. A woven fabric
`layer is bonded to the thermoplastic composite core by a
`resin, such as a resinous adhesive. This woven fabric layer
`is more elastic than the core so that upon thermoforming, the
`fabric layer conforms smoothly to the core without wrin(cid:173)
`kling.
`Woven fabrics are especially suited to this invention,
`since the alternative insertion of the fibers over one another
`in the woven pattern inherently provides some measure of
`pliability and elasticity. Additionally, the woven fabric can
`be embedded into the thermoplastic resin of the core so as
`to intimately contact or restrict the underlying fibers. In the
`preferred constructions, the fabric aids in preventing undue
`movement of the fiber reinforcement in the thermoplastic
`composite core to avoid buckling and wrinkling in the final
`molded article.
`This invention can also employ fabrics having a printed
`pattern so as to greatly improve the aesthetic appearance of
`the resulting molded article for consumer products. Ordinary
`natural and synthetic fibers can be employed with the variety
`of colors and patterns currently available in the textile
`industry.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The accompanying drawings illustrate preferred embodi(cid:173)
`ments of the invention so far devised for the practical
`application of the principles thereof, and in which:
`
`

`

`5,529,826
`
`5
`FIG. 1: is a front perspective view of a preferred unidi(cid:173)
`rectional fiber reinforced thermoplastic composite tape of
`this invention;
`FIG. 2: is a front perspective view of a composite sheet
`composed of a plurality of the composite tapes of FIG. 1 5
`which have been seamed together along their longitudinal
`sides;
`FIG. 3: is a top perspective view of an alternative com(cid:173)
`posite sheet illustrating a plurality of composite tapes of
`FIG. 1 woven to form a fabric;
`FIG. 4: is a top planar view of a reinforcing scrim;
`FIG. 5: is a top planar view of a printed fabric;
`FIG. 6: is a top perspective view of a preferred polymer
`matrix composite of this invention including a laminated,
`thermoplastic composite core and a pair of fabric facing
`layers; and
`FIG. 7(a)-(d): diagrammatically illustrate a preferred
`thermoforming sequence for preparing molded articles pur(cid:173)
`suant to this invention.
`
`20
`
`10
`
`6
`example, in carbon-reinforced composites, fatigue, and ten(cid:173)
`sile performance of chopped-mat reinforcement is signifi(cid:173)
`cantly lower than that of a woven, cross-ply fabric.
`Advanced composites, such as unidirectional carbon/
`thermoplastic laminates can have better fatigue resistance
`than steel, aluminum, or glass-reinforced composites. Com(cid:173)
`pared with unidirectional laminates, the fatigue strengths of
`other reinforcement types in decreasing order are: 85%
`unidirectional, cross-ply, glass fabric, and randomly oriented
`short fibers. Accordingly, this invention prefers that the
`fibers are unidirectional and that the composite material
`contain a laminated structure. Discontinuous fibers more
`closely model the fatigue strength of the polymer matrix,
`making fiber-to-matrix bonding more important for opti-
`15 mum performance.
`Presently, the preferred fibers of this invention comprise
`carbon, glass, such as E-glass and S-glass, boron, ararnid,
`such as KEVLAR® 29 or KEVLAR® 49 (available from du
`Pont), ceramic fibers, metallic fibers, and metal coated
`fibers.
`The above-described thermoplastic resins and reinforcing
`fibers can be arranged in a number of variations to produce
`dozens of thermoplastic-fiber composites. Some of these
`variations are described, along with their resulting fatigue
`25 properties, in Table I below:
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`Polymer matrix composites are provided by this invention
`which contain fabric facing layers disposed on thermoplastic
`composite cores. These composite materials can be thermo(cid:173)
`formed to provide a smooth fabric surface which is virtually
`free of wrinkles, kinking, and buckling. As used herein, the
`term "thermoplastic" refers to any polymer resinous material 30
`or blend that softens upon heating and solidifies upon
`cooling and can be thermoformed by application of heat and
`pressure. The term "fabric layer" is a relatively broad term
`meant to encompass both woven and nonwoven fabric layers
`and scrims. Finally, the term "elasticity" means the ability of 35
`a material to distort elastically as result of the construction
`of the material or due the inherent tensile elongation prop(cid:173)
`erties of the plastic or fibers used in the material.
`With reference to the Figures, and particularly to FIGS. 40
`1-3 and 6 thereof, the thermoplastic composite core of this
`invention will now be described. The thermoplastic com(cid:173)
`posite core includes a thermoplastic matrix containing a
`reinforcement, preferably reinforcing fibers, and also singu-
`lar layers of thermoplastics sandwiched in the composite 45
`core.
`The thermoplastic matrix of the composite cores of this
`invention contain one or more thermoplastic resins, alloys or
`copolymers. Typical resins useful in this regard include
`acetal, acrylics, cellulosics, fluorocarbons, nylons, polyal- 50
`lamer, polyaryl ether, polyaryl sulphone, polycarbonate,
`polyethylenes, polyimide, polyphenylene sulfide, polypro(cid:173)
`pylene, polystryrene, polyurethane, polyvinyl chlorides, sty(cid:173)
`rene acrylonitrile, polyphenylene oxide, polysulfone, poly(cid:173)
`ether sulfone, polymethylmetha acrylates, polyesters (PET, 55
`PBT), and their respective copolymers, compounds, and
`derivatives.
`The preferred reinforcing fibers 12 of this invention are of
`the light-weight and high-strength high modulus variety,
`such as carbon, glass, aramid, metal, or ceramic fibers. 60
`These fibers are preferably uniformly distributed throughout
`the composite to about 10-80 vol. % and preferably at least
`about 30% volume. Factors that influence the fatigue resis(cid:173)
`tance and tensile properties of reinforced thermoplastics
`include the proportion of reinforcing fibers, morphology of 65
`the reinforcement (i.e. random chopped mat, unidirectional
`fiber, or woven cross-ply roving), and the matrix resin. For
`
`TABLE I
`
`Fatigue Strength of Reinforced Thermoplastics'
`
`Glass
`fibers,
`
`Carbon
`fibers,
`
`Strength, x 103 psi
`
`Material
`
`Acetal
`Copolymer
`Nylon 62
`Nylon 6/6
`Nylon 6/62
`Nylon 6/62
`Nylon 6/62
`Nylon 6/6
`Nylon 6/62
`Nylon 6/6'
`Nylon 6/102
`Nylon 6/102
`Polycarbonate
`Polycarbonate
`Polyester, PBT
`Polyester, PBT
`Polyetheretherke-
`tone
`Polyethersulfone
`Polyethersulfone
`Polyethersulfone
`Mod.
`Polyphenylene
`Oxide
`Polyphenylene
`Sulfide
`Polysulfone
`Polysulfone
`
`%
`
`30
`
`30
`
`30
`40
`40
`
`30
`40
`20
`40
`30
`
`30
`40
`
`30
`
`30
`40
`
`%
`
`@ 104 cycles @ 107 cycles
`
`9
`
`7
`6
`3.4
`8
`9
`10.5
`13
`15
`7
`8
`9
`14.5
`11
`13
`18
`
`16
`19
`22
`7
`
`13
`
`14
`16
`
`30
`40
`
`30
`30
`
`30
`
`30
`
`7
`
`5.7
`5
`3
`6
`7
`9
`8
`8.5
`5.5
`7
`5
`6
`5
`6.5
`17.5
`
`5
`6
`6.7
`4.7
`
`9.5
`
`4.5
`5.5
`
`1Tests by ASTM D 671 at 1,800 cycles/min., as reported in Advanced
`Materials & Processes, Vol. 137, Issue 6, p. 102 (June 1990).
`2Moisture conditioned, 50% R.H.
`
`The thermoplastic composite core of this invention can be
`fabricated in a number of ways. One method is to begin with
`continuous rovings or bundles of fibers. The rovings are
`spread out to separate the filaments and then they are passed
`through a fluidized bed of thermoplastic resin powder. The
`spread fibers pick up the powder as they pass through the
`fluidized bed. The now resin-coated fibers are heated to the
`melting point of the thermoplastic resin in an oven to
`
`

`

`5,529,826
`
`5
`
`20
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`25
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`30
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`7
`smoothly coat the fibers to wet them out completely, or as
`nearly completely as the process permits. Since the now(cid:173)
`coated fiber bundle is in a nongeometric shape, it is then
`passed through a die or former to shape the bundle in!o a
`tape-like configuration. This tape preferably has a width
`which is much greater than its thickness. The thickness
`should be at least 50 µm so as to have sufficient strength to
`withstand mechanical working into the final thermoplastic
`matrix, and a preferred width of at least about 3 mm to avoid
`over twisting during the subsequent mechanical operations. 10
`Alternatively, the fibers may be passed through an extru(cid:173)
`sion cross-head die containing a bath of molten thermoplas-
`tic polymer. As the fibers pass through the die, the molten
`polymer coats the fibers and completely wets them out. This
`operation could also be followed by a shaping step to
`configure the coated bundle of fibers into a tape configura(cid:173)
`tion. Other methods include passing the fibers through a
`solution in which the polymer powder is suspended, or
`sandwiching the fiber web between films of polymer, and
`then passing them through heated laminated rollers under
`pressure and elevated temperature to coat them. Both of
`these fabrication methods can be additionally followed by a
`forming step to produce tapes.
`The end result of these impregnation methods is that a
`tape 10 is formed in which there are continuous unidirec(cid:173)
`tional fibers 12 in the axial or longitudinal direction, and that
`these fibers 12 are encapsulated within a thermoplastic,
`thermoformable matrix 14, as substantially described in
`FIG. l.
`In order to produce a panel from these unidirectional fiber
`reinforced thermoplastic tapes 10, a plurality of tapes can be
`woven into sheet fabric, such as woven sheet of tape 30,
`shown in FIG. 3. In this woven sheet 30, the tapes 10 are
`oriented in the 0° and 90° direction. Such woven construc(cid:173)
`tions are disclosed in U.S. Pat. No. 5,082,701, which is
`hereby incorporated by reference. Alternatively, the tapes
`can be placed adjacent to one another and seamed, attached,
`welded, or stitched in position before laying the next tape 10
`as shown by seamed sheet 20 of FIG. 2.
`In an alternative procedure for constructing panels, a
`"commingled fiber fabric" is produced. Fibers or thermo(cid:173)
`plastic resin and reinforcing fibers are commingled into a
`yam. The commingled yams are then woven into fabric. The
`fabric or layers of fabric are compression molded into a flat
`laminate under heat and pressure. The resin fibers melt and
`flow to wet out the reinforcing fibers.
`In still another method, an "assembled composite" can be
`produced. In such a method, woven or nonwoven fabric
`random or directional webs of reinforcing fibers are alter-
`nately stacked with a layer of thermoplastic film or powder.
`This assembly is then consolidated into a laminate under
`heat and pressure. Also, the method described by Fitchmun,
`U.S. Pat. No. 4,778,717 whereby a fabric is dipped in a
`liquid resin may be employed.
`Referring to the polymer matrix composite material 100,
`shown in FIG. 6, it will be understood that the preferred
`thermoplastic composite core is produced by laminating at
`least two thermoplastic sheets comprising unidirectional
`fibers having different orientations. These sheets are desir- 60
`ably placed on top of one another; for instance in a 0°190°I
`0°190° orientation that would be functional. However, it will
`be understood that there are numerous orientations and ply
`combinations.
`The sheets used in the thermoplastic composite core in
`this embodiment can be thermoformed to laminate them
`together into a integral composite. In one manufacturing
`
`8
`sequence, the laid up sheets are placed in a compression
`molding press, where heat and pressure are used to consoli(cid:173)
`date the assembled sheets into a nearly void-free solid
`composite laminated panel. It is envisioned that both seamed
`sheets 20 and woven sheets 30 can be used interchangeably
`in the laminated construction. Alternatively, commingled
`fibers fabric or the assembled composite (described above)
`can be incorporated into the structure of the laminated
`composite panels.
`Additionally, a thin thermoplastic film can be placed on
`both sides of the laminated composite, particularly if the top
`laminated sheets contain woven tapes, to fill in any voids
`resulting in the lamination of the woven pattern. The poly(cid:173)
`meric ingredients disclosed for the matrix of the thermo-
`15 plastic composite core would be suitable resins for this film.
`The preferred fabric layer 40 of this invention will now be
`described. Although woven and nonwoven fabrics and
`scrims are suitable for this invention, woven fabrics are the
`most desirable. A fabric 40, such as that described in FIG. 4,
`is a nonwoven fabric, screen of bonded fibers or a woven
`fabric, whereby the construction permits the yams or indi(cid:173)
`vidual fibers to move relative to their intersection points.
`The fabric layer of this invention does not necessarily
`need to contribute to the mechanical properties of the panel,
`therefore it does not have to, but may, contain high strength
`fibers, such as those types of fibers reinforcing the thermo(cid:173)
`plastic composite core. Instead of carbon, glass, or aramid
`fiber, the fabric layer 40 of this invention preferably contains
`ordinary, natural, or synthetic fibers, such as cotton, wool,
`silk, rayon, nylon, polyester, polypropylene, polyethylene,
`etc. The advantage of using these traditional textile fibers, is
`that they are available in many colors and can provide an
`infinite variety of patterns and textures to the preferred
`fabric layers. Such fibers can be woven, or spunbonded to
`produce nonwoven textile fabrics. Alternatively, plain color
`fabric can be easily dyed and printed in a variety of colors
`and patterns. Additionally, reinforcing fibers, such as glass,
`carbon, and aramid, could be used for surface fabric, pro-
`vided the overall fabric construction allows sufficient elas-
`ticity.
`As described in FIG. 5, the preferred woven fabric 50 can
`include a printed, aesthetically appealing printed pattern.
`The pattern can be created by weaving different colored
`fibers into an ornamental design, however, this would
`involve using numerous yam inputs with different colors in
`the warp, and complex weft inputs to obtain sophisticated
`patterns. A less expensive alternative would be to use
`commercially available patterned
`fabrics, which are
`intended for garments or furniture, etc., and apply these
`fabrics to the thermoplastic composite core of this invention.
`Accordingly, this invention prefers to employ consumer
`textile fabrics, imprinted with art work, logos, and trade(cid:173)
`marks which are printed, dyed, or silk screened onto the
`fabric.
`The fabric layers of this invention are preferably bonded
`to the resin-containing thermoplastic composite core with a
`"resinous adhesive" e.g. film, powder, or tacky material used
`to bond the fabric to the core. One preferred method of
`applying the fabric layer to the core is to prepare a thin film,
`10 µm to 500 µm thick, made from a compatible thermo-
`plastic resin as the matrix of the thermoplastic composite
`core. This film can be placed over the core and the fabric
`layer is then placed onto this film. Another film of the same
`65 or silnilar composition is preferably applied to the top of the
`fabric. The assembly including the core, fabric layer, and the
`layers of thermoplastic film is then placed into a compres-
`
`35
`
`40
`
`45
`
`50
`
`55
`
`

`

`5,529,826
`
`5
`
`9
`sion molding press which subjects the components to
`elevated heat and pressure. The films, fabric, and core are
`thereafter consolidated and fused into an integral panel
`shape. The total amount of film needed to fully bond,
`incorporate, and/or cover the fabric depends upon the thick-
`ness, porosity, and texture or the fabric. As a rule of thumb,
`the total film thickness should be about 0.3 to about 3.0
`times the thickness of the fabric. One may use more film
`below or above the fabric to impart aesthetic appearances,
`e.g., texture, depth, etc.
`In the most preferred construction, the fabric layer weave
`and the fiber construction of the core are chosen so that the
`melted film resin flows through the interstices in the fabric
`layer weaving to anchor the fabric to the panel. Additionally,
`the fibers of the fabric layer can be intertwined and bonded
`closely with the fibers of the core to increase the adhesion of 15
`the fabric layer to the core. It is further envisioned that the
`thermoplastic film can be substituted by an evenly distrib(cid:173)
`uted resin powder or a suitable adhesive to achieve the same
`result. The fabric, thus applied to one or both planar surfaces
`of the panel-like core, becomes the outermost layer of the 20
`composite material, and acts to overcome the problems of
`wrinkling, and a lack of an aesthetic appearance usually
`associated wit