FLEXIBLE COMPOSITE SYSTEMS
A system for providing improved flexible-composite materials, equipment, and manufacturing processes including improved flexible composite materials that include scrim reinforcements.
This application claims priority to U.S. Provisional Patent Application Ser. No. 61/780,821, filed Mar. 13, 2013, which is hereby incorporated by reference in its entirety.
BACKGROUNDRelated disclosures are found in U.S. Pat. No. 5,470,062, entitled “COMPOSITE MATERIAL FOR FABRICATION OF SAILS AND OTHER ARTICLES,” which was issued on Nov. 28, 1995; and U.S. Pat. No. 5,333,568, entitled “MATERIAL FOR THE FABRICATION OF SAILS” which was issued on Aug. 2, 1994; and U.S. patent application Ser. No. 13/168,912, filed Jun. 24, 2011 entitled “WATERPROOF BREATHABLE COMPOSITE MATERIALS FOR FABRICATION OF FLEXIBLE MEMBRANES AND OTHER ARTICLES,”; and U.S. patent application Ser. No. 13/197,741, filed Aug. 3, 2011 entitled “SYSTEM AND METHOD FOR THE TRANSFER OF COLOR AND OTHER PHYSICAL PROPERTIES TO LAMINATE COMPOSITE MATERIALS AND OTHER ARTICLES”, the contents of all of which are hereby incorporated by reference for any purpose in their entirety.
This invention relates to improved flexible composite systems that include scrim reinforcements. More particularly, this invention relates to a system for providing improved flexible-composite materials, equipment, and manufacturing processes.
Flexible-composite materials are widely used in applications requiring both mechanical flexibility and high strength-to-weight ratios. Although flexible-composite materials may be considered a specialized subset of the larger body composite-materials, their importance in many specific areas of technology is significant.
As the term suggests, composite materials combine two or more constituent materials to form a unified material composition. An example of a flexible composite material would be a polymer matrix embedding an arrangement of flexible fibers.
Utilization of flexible-composite materials is envisioned in many technical fields ranging from simple consumer products to advanced aerospace applications. A system for quickly and economically producing high-quality flexible-composite materials would be of benefit to many.
OBJECTS AND FEATURES OF THE INVENTIONA primary object and feature of the present invention is to provide a system addressing the above-mentioned need.
It is a further object and feature of the present invention to provide such a system for quickly and economically producing high-quality flexible-composite materials that include scrim reinforcements. Another primary object and feature of the present invention is to provide a system using woven fabric reinforcements.
Another primary object and feature of the present invention is to provide a system to fine-tune, at desired places on a product, directional control of rigidity/flexibility/elasticity properties.
Yet another primary object and feature of the present invention is to provide products combining extreme light weight with extreme strength.
It is a further object and feature of the present invention to provide such a system providing continuous bulk manufacture of such products and their constituent parts.
Another object and feature of the present invention is to provide adaptability to the various stations of such continuous bulk manufacturing system.
It is another object and feature of the present invention to provide such a system utilizing essentially one or more continuous “roll-to-roll” production process.
A further primary object and feature of the present invention is to provide such a system that is efficient, inexpensive, and useful. Other objects and features of this invention will become apparent with reference to the following descriptions.
SUMMARY OF THE INVENTIONIn accordance with a preferred embodiment hereof, this invention provides a laminate including scrim reinforcing elements therein, such reinforcing elements including at least two unidirectional tapes having monofilaments therein, all of such monofilaments lying in a predetermined direction within the tapes, wherein such monofilaments have diameters less than 20 microns and wherein spacing between individual monofilaments within an adjoining strengthening group of monofilaments is within a gap distance in the range between non-abutting monofilaments up to nine times the monofilament major diameter.
In addition, this invention provides a laminate including woven fabric reinforcing elements contained therein. Moreover, it provides such a laminate wherein such monofilaments are gap spaced. Also, it provides such a laminate wherein each of such at least two unidirectional tapes includes larger areas without monofilaments therein and wherein such larger areas comprise laminar overlays comprising smaller areas without monofilaments.
In addition, it provides such a laminate wherein such smaller areas comprise user-planned arrangements. And, it provides such a laminate further comprising a set of water-breathable elements comprising laminar overlays of such smaller areas. Further, it provides such a laminate further comprising a set of other laminar overlays. Moreover, it provides such a laminate wherein a first one of such at least two unidirectional tapes includes monofilaments lying in a different predetermined direction than a second one of such at least two unidirectional tapes.
Additionally, it provides such a laminate wherein a combination of the different predetermined directions of such at least two unidirectional tapes is user-selected to achieve laminate properties having planned directional rigidity/flexibility. Also, it provides such a laminate comprising a three-dimensionally shaped, flexible composite part. In addition, it provides such a product comprising multiple laminate segments attached along peripheral joints. And, it provides such a product comprising at least one laminate segment attached along peripheral joints with at least one non-laminate segment. Further, it provides such a product comprising multiple laminate segments attached along area joints.
Even further, it provides such a product comprising at least one laminate segment attached along area joints with at least one non-laminate segment. Moreover, it provides such a product comprising at least one laminate segment attached along area joints with at least one unitape segment. Additionally, it provides such a product comprising at least one laminate segment attached along area joints with at least one monofilament segment. Also, it provides such a product further comprising at least one rigid element.
In accordance with another preferred embodiment hereof, this invention provides a product wherein such at least one unidirectional tape is attached to such product. In accordance with a preferred embodiment hereof, the present system provides each and every novel feature, element, combination, step and/or method disclosed or suggested by this patent application.
BRIEF GLOSSARY OF TERMS AND DEFINITIONSAdhesive: A curable resin used to combine composite materials.
Anisotropic: Not isotropic; having mechanical and or physical properties which vary with direction at a point in the material.
aerial weight: The weight of fiber per unit area, this is often expressed as grams per square meter (g/m2).
Autoclave: A closed vessel for producing an environment of fluid pressure, with or without heat, to an enclosed object which is undergoing a chemical reaction or other operation.
B-stage: Generally defined herein as an intermediate stage in the reaction of some thermosetting resins. Materials are sometimes pre cure to this stage, called “prepregs”, to facilitate handling and processing prior to final cure.
C-Stage: Final stage in the reaction of certain resins in which the material is relatively insoluble and infusible.
Cure: To change the properties of a polymer resin irreversibly by chemical reaction. Cure may be accomplished by addition of curing (cross-linking) agents, with or without catalyst, and with or without heat.
Decitex (DTEX): Unit of the linear density of a continuous filament or yarn, equal to 1/10th of a tex or 9/10th of a denier
Dyneema™ Ultra-high-molecular-weight polyethylene fiber by DSM
Filament: The smallest unit of a fiber-containing material. Filaments usually are of long length and small diameter.
Polymer: An organic material composed of molecules of monomers linked together.
Prepreg: A ready-to-cure sheet or tape material. The resin is partially cured to a B-stage and supplied to a layup step prior to full cure.
Scrim: Light woven or non-woven fabric with relatively large openings between the yarns, used to reinforce paper and other products.
Tow: An untwisted bundle of continuous filaments.
UHMWPE: Ultra-high-molecular-weight polyethylene. A type of polyolefin made up of extremely long chains of polyethylene. Trade names include Spectra® and Dyneema®
Unitape Uni-Directional tape (UD tape)—flexible reinforced tapes (also referred to as sheets) having uniformly-dense arrangements of reinforcing fibers in parallel alignment and impregnated with an adhesive resin. UD tape are typically B-staged and form the basic unit of most CT composite fabrics.
The present invention relates to composite materials that contains at least one scrim reinforcement. In addition, the present invention relates to composite materials that contains at least one woven fabric reinforcement.
A composite material contains one or more unidirectional fiber-reinforced layers each having thinly spread parallel fibers coated with adhesive (these layers are termed unitapes).
A key feature of the present system is the thin unitape layers manufactured using untwisted fiber bundles consisting of a plurality of monofilaments that are combined with a polymer resin and are pultruded through a rotary die such that the monofialments are spread and oriented parallel to each other. A second key feature is that the composite material includes a woven or non-woven reinforcement laid scrim such as produced by Saint Gobain Adfors.
Preferred laid scrim is a lower cost reinforcing fabric made from continuous filament yarn in an open mesh construction. The laid scrim manufacturing process chemically bonds non-woven yarns together, enhancing the scrim with unique characteristics. The laid scrim is a cost effective way to add fiber reinforcement to a composite material, especially in bias orientations (+/−30°, +/−45°, +/−60°) because the added processing steps to add unitape bias plies are skipped and replaced by inserting a pre-manufactured scrim. The laid scrim may be pre-coated with adhesive or it may be necessary to sandwich it between unitape layers to glue it in place.
Additional films, membranes, fabrics, or coatings may be applied to the outer surfaces or layered within this composite material.
Reference is made to the following materials found on the following website (http://www.sg-adfors.com/Technologies/Fabrics/LaidScrim)
Preferred Scrim Fibers used include:
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- Fiberglass
- Polyester
- Synthetic polymer fibers, natural fibers and high-modulus yarns can also be processed
Scrim Features and benefits include:
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- Dimensional stability
- Tensile strength
- Alkali resistance
- Tear resistance
- Fire resistance
- Anti-microbial properties
- Water resistance
Reference is made to the following materials found on the following website (http://www.sg-adfors.com/Technologies/Fabrics/LaidScrim/ConstructionPatterns)
As noted above, a composite material contains one or more unidirectional fiber-reinforced layers each having thinly spread parallel fibers coated with adhesive (these layers are termed unitapes). A key feature of the invention is the thin unitape layers manufactured using untwisted fiber bundles consisting of a plurality of monofilaments that are combined with a polymer resin and are pultruded through a rotary die such that the monofilaments are spread and oriented parallel to each other. The key feature of this preferred embodiment is that the fibers that make up the unitape are spread and either the distance between fibers is “gapped” such that an adhesive and fiber free space between each group of monofilaments is formed, or fiber tows are removed after the monofilaments have been spread resulting in a similarly gapped unitape. A preferred scrim is formed by bonding two or more of these unitape layers together. In an alternative embodiment a breathable or non-breathable adhesive may be used to fill the gaps.
This product is useful because it can be used in breathable membrane applications due to the adhesive/fiber free gaps.
Preferably, additional films, membranes, fabrics, or coatings may be applied to the outer surfaces or layered within this composite material.
Preferably, the material layers are combined and cured together using pressure and temperature either by passing the stacked layers through a heated set of nips rolls, a heated press, a heated vacuum press, a heated belt press or by placing the stack of layers into a vacuum lamination tool and exposing the stack to heat. Moreover, external pressure, such as provided by an autoclave, may also be used to increase the pressure exerted on the layers. The vacuum lamination tool may be covered with a vacuum bag sealed to the lamination tool with a vacuum applied to provide pressure. Other lamination methods may also be suitable as would be known to one skilled in the art.
Thus, according to preferred embodiments of the present system, at least one roll-to-roll coating process is preferably used to impregnate at least one scrim or fabric to form at least one flexible-composite material 100. Preferred fabrics usable in the present system preferably include Nylon, Polyester, UHPWPE (Spectra, Dyneema), para-Aramids (Kevlar, Nomex, Technora, Twaron), Liquid Crystal Polymer (Vectran), Polyimide, other synthetic polymers (PBO, PBI, PIBT, PBZT, PLA, PPTA), metal fiber, glass fiber or some combination of each.
It should be noted that some low-surface-energy fabrics preferably require surface-energy modification prior to coating to promote bonding of the coating. Preferred surface treatments include flame treatment, corona, plasma, and/or chemical treatment process. Subsequent, coating processes preferably include curtain coating, gap coating, gravure coating, immersion coating, knife-over-roll coated, metered rod coating, reverse roll coating, roller coater, extrusion coating.
Methods to partially or completely cure the above-noted coating preferably include heated rolls, ovens, vacuum ovens, using light, Infrared, or UV curing. In one preferred embodiment of the present system, a low temperature curing adhesive is used because the selected fabric is especially temperature sensitive. UWMWPE fabrics, for example, decompose at temperatures greater than 300° F. and the advised short-term duration temperature limit is 145° C. In another preferred embodiment, a thermoset or partially thermoset adhesive is preferably used because this coating is more robust and does not degrade with heat and UV exposure. In another preferred embodiment a thermoplastic adhesive is preferably used, such as urethane, when subsequent bonding and seaming processes may require a thermoplastic coating. If adhesive is only partially cured during coating process, a subsequent curing step is preferably used to fully cure the product, subsequent preferred curing methods include to heated rolls, ovens, vacuum ovens, using light, Infrared, or UV curing, or autoclaves.
Roll-to-Roll Coating Process Followed by Autoclave Cure
In another preferred embodiment of the present system, the uncured or partially cured coated fabrics described in the previous embodiments proceed to an autoclave curing process. Preferably, the uncured or partially cured coated fabric is placed between layers of release liner (preferably comprising a fluoropolymer film or Teflon), next applied are layers of peel ply and breather, and the stack is preferably sealed in a vacuum bag onto a hard caul. The autoclave preferably uses controlled temperature, pressure, and vacuum to remove entrapped air and volatiles from the coating and flow the coating evenly across the surface and through the thickness of the fabric. The resulting coating is fully impregnated into the fabric. The preferred autoclave process allows for thinner coatings than traditional coating processes because of the even re-flow of adhesive; as a result, lighter weight fabrics are possible.
Fiber reinforced adhesive sheet (unitape) or non-fiber reinforced adhesive sheet, layered in specific orientations, laminated to a fabric product, cured in or out of autoclave
A preferred unidirectional (UD) tape is preferably manufactured by spreading fibers and coating them with an adhesive onto a release paper to form a continuous sheet. This preferred unidirectional tape is non-woven. Preferably, these unitape sheets are cut to size and layered in multiple orientations to form a preferred two directional fiber reinforced sheet (examples 0°/90°, +45°/−45°, +30°/−30°), or a preferred four directional fiber reinforced sheet (preferred examples 0°/90°/45°/−45°, 0°/90°/30°/−30°), or other preferred “custom” oriented fiber reinforced sheet with many orientations and layer combinations envisioned by Applicant. These preferred reinforced sheets are preferably laminated to at least one fabric. In one preferred embodiment of the present system, the non-woven reinforced sheets are laminated to both sides of the fabric. In another embodiment, the non-woven reinforced sheet is laminated between fabrics. In another embodiment, a unreinforced adhesive sheet tape is produced by coating a release paper with adhesive. The adhesive sheet tape is then applied to the fabric by laying the sheets of adhesive on the fabric and removing the release paper. Multiple overlapping adhesive layers may be added and to one or both sides of the fabric. The resulting coated fabric, with or without additional reinforcement from fiber reinforced unitape layers is cured in a roll-to-roll process or in an autoclave as previously described.
Bonding of Similar or Dissimilar Fabrics Together Using Roll-to-Roll Coating Process or Autoclave
Fabrics are preferably coated and two layers or multiple layers of similar or different uncured fabrics are preferably laminated together. Final cure preferably occurs in a roll-to-roll curing method such as, for example, heated rolls, ovens, vacuum ovens, using light, Infrared, UV, or autoclave process.
Addition of Plastic Film or Fabric on One or Both Sides
In preferred embodiments, at least one plastic film such as PET, PEN, Nylon, fluoropolymer, urethane, or others are laminated to one or both sides of the above-mentioned embodiments or alternately-preferably between layers of the above-mentioned embodiments prior to the curing process. In another preferred embodiments a non-impregnated fabric is preferably laminated to one or both sides of the previous embodiments or between layers of the above-mentioned embodiments prior to the curing process.
It is noted that preferred fabrics utilized within the preferred embodiments of the present system include wovens, knits, imaginable square weave, basket weave, warp knit, fleece, and the like.
A Preferred Example Embodiment and Production Methodology
Procedure:
1) Corona Treat Woven UHMWPE Fabric
UHMWPE fibers (trade names Spectra & Dyneema) require surface treatment to promote adhesion of the coating. Preferably, a woven fabric roll is loaded onto a machine that passes the fabric through a corona treater and the fabric is then re-rolled. Applicant's preferred corona treater energizes only one side of the fabric so the fabric must be turned over and passed a second time through the corona to treat the opposite side. Other preferred treaters energize both surfaces in a single pass. A run speed of about 10 ft/min and corona energy level of about 1 kW are Applicant's preferred machine settings.
2) Manufacture Precursor Sheet Adhesive
The coating for this application is a preferred proprietary partially thermosetting polymer that has excellent adhesion to low surface energy fibers and films and forms a toughened finished product once cured that is puncture resistant and resists UV degradation. Applicant's internal trade name of this coating adhesive is CT71. Pigments, fire retardants, or UV blocking additives are preferably mixed with the adhesive to customize its visual or physical properties. The preferred adhesive in liquid form is preferably pumped onto and extruded between two rollers between top and bottom release papers. Preferably, the top release paper has a lower surface energy than the bottom release paper so that it can be easily removed later in the process leaving the adhesive still stuck to the bottom paper. The preferred adhesive sheet is preferably passed through an oven and a series of heated or cooled rollers to evenly spread and partially cure the adhesive. The preferred adhesive sheet, preferably sandwiched between top and bottom release papers is preferably rolled onto about a 10″ diameter cardboard core at the end of this preferred process. Preferably, the rolls are then bagged and stored according to internal procedures. The preferred resulting adhesive sheet is approximate 13.5″ wide. Target adhesive areal weight is preferably between 100 and 125 g/m2.
3) Lamination/Coating Process
The preferred treated woven UHMWPE fabric is preferably pulled twice through a laminating machine where adhesive sheets are preferably applied first to one side and then to the other side of fabric. The fabric is preferably loaded onto unrolling equipment at the front end of the machine and preferably pulled through to the uptake roll at the back end of the machine. Adhesive sheets are preferably cut from the precursor sheet adhesive roll to the desired length; this length is just shorter than the width of the fabric. The top release paper is preferably peeled from the adhesive sheet leaving the adhesive exposed. Operators preferably place this sheet, adhesive face down onto the fabric. Preferably, the long direction of the adhesive sheet is perpendicular to the lamination machine direction. The adhesive sheets, preferably with bottom release paper still attached, are preferably overlapped about a half-inch so that there are no gaps in the coating. The preferred fabric and adhesive sheets with bottom release paper are preferably passed through a set of heated rollers to bond the adhesive to the fabric. After this set of rollers, operators preferably remove the bottom release paper from the adhesive sheet. Operators preferably cut small pieces of the precursor sheet adhesive roll to create adhesive patches to repair coating gaps or holes in the adhesive coated fabric. At the back end of the machine the material is preferably re-wound preferably with a 0.5 mil ECTFE release liner facing the coating. The internal trade name for this release liner is FC3-0.5. After a length of fabric has been coated on one side, the coated roll is preferably removed from the back of the machine, turned over and preferably re-loaded onto the unrolling equipment on the front of the machine (first remove the uncoated fabric roll). The process is preferably repeated to coat the backside of the fabric. Preferably, a FC3-0.58 release liner is also applied to this side.
4) Cure Process Preferably, the uncured coated fabric proceeds to an autoclave curing process. An aluminum caul preferably covers the length of a cure table. Next, a layer of peel ply is unrolled, preferably followed by a layer of the uncured coated fabric already sandwiched between FC3-0.5 release film. Preferably, a second layer of peel ply is rolled over the FC3-0.5 and another aluminum caul is placed on top of this layer of peel ply. Multiple layers of caul/peel ply/FC3-0.5/coated fabric/FC3-0.5/peel ply/caul may be stacked. On top of this stack is preferably a thick breather and then preferably a vacuum bag is used to seal the stack. The length of these coated fabric panels is limited to the length of the cure table. For current embodiments, this length is about 9 meters. The cure table is preferably pushed into the autoclave. The autoclave preferably uses controlled temperature, pressure, and vacuum to remove entrapped air and volatiles from the coating and flow the coating evenly across the surface and through the thickness of the fabric. Preferably, the resulting coating is fully impregnated into the fabric. The preferred autoclave process allows for thinner coatings than traditional coating processes because of the even re-flow of adhesive; as a result, lighter weight fabrics are possible. It is noted that detailed autoclave process parameters are described in greater detail in Applicant's U.S. Pat. No. 5,470,632 incorporated herein by reference for further examples of implementation engineering. Once the autoclave cure cycle is finished, the cured coated fabric is preferably removed from the autoclave and rolled. It is recommended to leave the release liners on the finished product to prevent the fabric from adhering to itself after storage or shipment.
Preferably, the Composite Material may include coloration of the matrix or membranes through use of pigments or dye sublimation.
Preferably, a fire retardant adhesive or polymer may be used, or fire retardants can be added to a flammable matrix or membrane to improve the flame resistance. Flame retardance or self extinguishing matrix resins or laminating or bonding adhesives such as Lubrizol 88111 can be used. Either by themselves or in combination with fire retardant additives. Examples of retardant additives include: DOW D.E.R. 593 Brominated Resin, DOW Corning 3 Fire Retardant Resin, and polyurethane resin with Antimony Trioxide (such as EMC-85/10A from PDM Neptec ltd.), although other fire retardant additives may also be suitable. Fire retardant additives that may be used to improve flame resistance include Fyrol FR-2, Fyrol HF-4, Fyrol PNX, Fyrol 6, and SaFRon 7700, although other additives may also be suitable. Fire retardancy and self extinguishing features can also be added to the fibers either by using fire retardant fibers such as Nomex or Kevlar, ceramic or metallic wire filaments, direct addition of fire retardant compounds to the fiber formulation during the fiber manufacturing process, or by coating the fibers with a sizing, polymer or adhesive incorporating fire retardant compounds listed above or others as appropriate. Any woven or scrim materials used in the laminate may be either be pretreated for fire retardancy by the supplier or coated and infused with fire retardant compounds during the manufacturing process.
Preferably, anti-microbial/anti-pathogen resistance may be added to the Composite Material by the incorporation of one or more of anti-microbial agents added or coated onto the polymer resins, or fabrics, and anti-microbial treatments to the fibers, monofilaments, threads or tows used for composite material. Typical materials include OXiTitan Antimicrobial, nano silver compounds, Sodium pyrithione, Zinc pyrithione 2-Fluoroethanol, 1-Bromo-2-fluoroethane, BenzimidaZole, Fleroxacin, 1,4-Butanedisulfonic acid disodium salt, 2-(2-pyridyl)isothiourea N-oxide hydrochloride, Quaternary ammonium salt, 2-Pyridinethiol 1-oxide, Compound Zinc pyrithione, Compound copper pyrithione, magnesium pyrithione, BISPYRITHIONE, pyrithione, ot-Bromo Cinnam-Gel, KFO ABC Silica Gel manufactured. Fiber forms such as threads, tows and monofilaments can be treated with silver nano particles, or can have silver coatings applied via chemical or electrical plating, vacuum deposition or coating with a silver compound containing polymer, adhesive or sizing. The anti-microbial/anti-pathogen materials may also be suitable.
Although applicant has described applicant's preferred embodiments of this invention, it will be understood that the broadest scope of this invention includes modifications such as diverse shapes, sizes, and materials. Such scope is limited only by the below claims as read in connection with the above specification. Further, many other advantages of applicant's invention will be apparent to those skilled in the art from the above descriptions and the below claims.
Claims
1. A flexible-composite material comprising:
- at least one scrim, each comprising at least two unidirectional tape layers bonded together; and
- at least one woven fabric, non-woven fabric, or membrane bonded to said at least one scrim,
- wherein said unidirectional tape layers comprise a plurality of untwisted and parallel fiber bundles comprising monofilaments in an adhesive resin, and
- wherein said fiber bundles are separated by gaps.
Type: Application
Filed: Mar 13, 2014
Publication Date: Nov 13, 2014
Inventors: Christopher Michael Adams (Mesa, AZ), Wesley Edward Hatcher (Mesa, AZ), Keith Joel McDaniels (Phoenix, AZ)
Application Number: 14/207,891
International Classification: B32B 5/02 (20060101); B32B 5/26 (20060101);
