Patent Application
20240368829
This application claims the priority to pending U.S. Provisional patent application Ser. No. 10/816,405 filed Jul. 30, 2022 which is incorporated herein by reference.
The present invention is related to the purposes and applications of permanent and penetrative coatings to a broad range of carbon, glass, polymer, cellulosic, protein and other fiber assemblies and filaments to enhance their aesthetic appearance with pigment, physical performance by changing strength or elongation, medical capability with antimicrobial material, or environmental sustainability.
Applying coatings to fibers or filaments and products comprising fibers or filaments is an important economic activity globally. Fiber assemblies, or superstructures, are made from fibrous materials, or substrates, ranging from cotton fibers to interlinked strands of carbon nanotubes. Fiber assemblies and filaments are traditionally colored using a combination of large water volumes, chemical dyes, heat, and high pressure. This process results in low penetration of color into the surface of the fiber assembly or filament, that can be later removed through use, chemical bleaches, and light of various spectra.
Chemical coatings are applied to fiber assemblies and filaments to improve aesthetics, physical performance or medical capability. In commonly utilized techniques the chemical coatings are applied to the surface of the fibers or bundles of fibers and then thermally or optically cured. These coatings are not robust and typically erode or abrade away quickly through planned use or exposure to daylight or other light sources.
In addition to the lack of robustness, prior art methods used for coating fiber assemblies and filaments have the disadvantage of utilizing hundreds to thousands of liters of clean water in the processing of each kilogram of material, as well as adding dozens of harmful chemicals to each of the processes used to add coatings, most of which are either discarded as lightly treated or untreated waste-water and other materials.
It has been discovered through diligent research that much of the lack of robustness is in weakness in the adhesion of the colorant or pigment to the fiber assemblies and filaments. An advanced materials approach is described herein wherein the robustness of the coating is significantly enhanced. In addition to providing enhanced robustness the present invention can be utilized with significantly less material usage which is economically and environmentally advantageous.
One aspect of the invention is the improved process for providing a penetrative and durable coating of superstructures, fiber assemblies and filaments or fibers, collectively fibrous strand, with materials that create an aesthetic change, such as color and/or texture, or performance oriented change, such as resistance to biological materials or enhancement of environmental requirements.
Another aspect of the invention is the use of corona discharge plasma reconfiguration of fibrous strands to ensure that the surface area is appropriately adhesive and that gaps are created that permit the penetrative and durable coating to become permanently affixed to the fibrous strands.
Another aspect of the invention is the exposure of the fibrous strands to an ionic, anionic, or acidic surfactant solution that further enhances surface adhesion and enlarges the gaps. A thermoplastic polymer is applied with sufficient energy to ensure that the physical parameters are preserved for the application of the coating material.
Another aspect of the invention is the use of a linear manufacturing system with elevated temperature and humidity to make sure electrical and chemical modification of the fibrous strands; preferably in the form of superstructures, filament assemblies, filaments or fibers, become permanent and resistant to future oxidative, heat, or other insults.
Another aspect of the invention is fibrous strands to an aero-diffusion device that applies a chemical mixture of coating material at a specific pressure to the top of the fibrous strands. The aero-diffusion device presents a chemical mixture of thermoplastic polymer and coating material having a particle size sufficient to promote specific performance such as imparting pigment, bacterial resistance, temperature resistance, strength enhancement, lubrication, luminosity, reflectivity, or environmental performance by creating physical links formed during a process or moderate heat, bringing about a cross-linking reaction, producing covalent bonds, which are insensitive to hydrolyzing agents.
Another aspect of this invention is that all fluids, surfactant solutions, water, pigments, and other chemicals are used in each process stage until they are exhausted and therefore minimal, if any, waste is produced and no gases or fluids are released to the environment for treatment or disposal.
These and other embodiments, as will be realized, are provided in a fibrous strand comprising at least one filament wherein said filament comprises a surface with gaps in the surface. A cured thermoplastic polymer is on the surface wherein the cured thermoplastic polymer comprises a coating material and the cured thermoplastic polymer and coating material extend into the gaps.
Yet another embodiment is provided in a process for forming a coated fibrous strand comprising:
The present invention is related to an improved process for coating fibrous strands; preferably in the form of superstructure, fiber assemblies, filaments or fibers; to form improved fibrous strands. More specifically, the present invention is related to a process for forming gaps in a fibrous strands followed by energized surfactants, energized thermoplastic polymer and coating material and an optional fixing to provide fibrous strands with improved coating robustness.
As used herein “filaments” or “fibers” are used interchangeably to refer to natural or synthetic substances that are significantly longer than they are wide typically in the form of very thin threads.
As used herein “fiber assemblies” are bundles of fibers or filaments taken together either parallel, wound or intertangled to form a single strand.
As used herein “superstructures” comprise multiple fiber assemblies taken together to form a shaped article.
As used herein, “flat plane” refers to the horizontal presentation of one, dozens, hundreds, or thousands of superstructure assemblies on a flat horizontal plane in which the superstructures are lying side-by-side and are slightly touching one another as measured in nanometers or micrometers.
As used herein, “corona discharge plasma” is a high voltage Corona Discharge Plasma which has the effect of modifying the surface to improve adhesion, permitting permanent coating in subsequent steps.
As used herein, “surfactant” refers to compounds that lower the surface tension between two liquids, between a gas and a liquid, or between a liquid and a solid. Surfactants are cationic, anionic, or acidic depending upon the surface presented for coating.
As used herein, “fibrous strand” is used for clarity to refer individually or collectively to a superstructure, fiber assembly, filament or fiber.
As used herein, “thermoplastic polymer” is a material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling. Particularly preferred thermoplastic polymers include polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), nylon (PA), polystyrene (PS), polyvinyl chloride (PVC), acrylonitrile butadiene styrene (ABS), ethylene vinyl acetate (EVA), thermoplastic polyurethane (TPU), polyolefin elastomers (POE), poly(methyl methacrylate) (PMMA), poly(ethyl acrylate) (PEA), poly(butyl acrylate) (PBA), poly(2-ethylhexyl acrylate) (PEHA), poly(acrylic acid) (PAA) and copolymers of acrylic acid and other monomers, such as styrene, acrylonitrile, and vinyl acetate.
The polymers mentioned above can be the fibers or the binder that holds the pigment. In either case, the polymer becomes part of the fiber bundle superstructure.
As used herein, “adhesion” refers to the tendency of dissimilar surfaces to cling to one another through dispersive adhesion with attractive forces created by intermolecular interactions between molecules of each material.
As used herein, “gaps” are rifts, fissures or cracks on the surface of a fibrous strand wherein the gaps are at least 1 nm to 10 microns across at the surface and the volume of the gaps represent 15% to 90% of the volume of the fibrous strand.
As used herein, “aero-diffusion” is a technique for applying a continuity of heterogeneous material or permanent coating to fibrous strand under the conditions of steady temperature-humidity. The continuity of the wetness technique is justified on the principle of equality of chemical potential.
As used herein, “fixing” is a chemical process that produces the toughening or hardening of polymer materials by cross-linking of polymer chains by exposure to temperature gradients.
As used herein, “penetration” refers to the extent to which coating materials and thermoplastic polymer penetrate the surface of a fibrous strand to form a core-shell structure with the fibrous strand as the core and the coating as the shell with preferably with at least 20 vol % of the gaps filled with thermoplastic polymer and coating material, more preferably at least 50 vol % and must preferably up to about 90 vol % of the volume of the gaps filled with thermoplastic polymer and coating material.
The invention will be described with reference to the figures which are integral, but non-limiting, part of the specification provided for clarity of the invention. Throughout the various figures similar elements will be numbered according.
An embodiment of the invention will be described with reference to
An embodiment of the invention will be described with reference to
In a particularly preferred embodiment the ultrasonic treatment element is configured to allow any surfactant not adhered to the wetted fibrous strand to be returned to, or remain in, the surfactant pool thereby mitigating material loss.
An embodiment of the invention will be described with reference to
An embodiment of the invention will be described with reference to
In a preferred embodiment the excess spray comprising thermoplastic polymer and a coating material is captured and returned to the aero-diffusion devices thereby minimizing lost material.
An embodiment of the invention will be described with reference to
In a preferred embodiment the excess fixing coating is captured and returned to the fixing element devices thereby minimizing lost material.
An embodiment of the invention is illustrated schematically in
The coating materials and thermoplastic polymer preferably have a particle size and chemical cross-linking ability to promote specific performance such as altering the aesthetics by including a pigment or colorant, alterations in electrical conductivity by including an electrical insulator or electrical conductor, antibacterial properties by including an antibacterial material, temperature resistance by including a temperature conductor or temperature insulator, strength enhancement by including a cross-linker, lubrication or anti-friction properties by incorporating a surface treatment material, luminosity by incorporating a light emitting or light absorbing material, reflectivity by including an optically reflective material, gas separation properties, by incorporating a pore former or environmental performance by including a hydrophobic or hydrophilic material.
Particularly preferred filaments or fibers include natural fibers, synthetic fibers, regenerated cellulose fibers, or speciality fibers. Particularly preferred natural fibers include: cotton, wool, silk, flax, linen, hemp, jute, ramie, coir, sisal, alpaca, cashmere, mohair, angora, camel hair, vicuna, spider web and the like. Particularly preferred synthetic fibers include: glass, carbon, aramid, polyester, Nylon 6, Nylon 66, acrylic, modacrylic, Spandex, Elastane, Lycra, olefin, PVC fibers, polypropylene, polyethylene and the like. Particularly preferred regenerated cellulose fibers include: bamboo, synthetic protein, synthetic spider web, cupro rayon, viscose rayon, acetate, lyocell, Tencel, modal, sorona, soy, seacell, kapok and the like. Particularly preferred specialty fibers include: gold, silver, copper, conductive fiber, antibacterial fiber such as silver or other material infused; flame retardant fibers such as polymers with mixed chemistry, brominated, chlorinated, or high-purity antimony trioxide; and the like.
The cured fibrous strand, and optional fixing coating is suitable for use in many applications including aerospace, automotive applications, construction applications, landscaping applications, industrial applications, scientific applications, apparel, home furnishings, military applications and the like.
The fibrous strands are typically provided from individual reels, packages or warp beams as well known in the art. The number of fibrous strands simultaneously fed into the inventive process is not particularly limited to the process and the process can be used between conventional feed systems and the finished product collected on convention collection systems without alteration. It is not uncommon in the art to have as few as 1 and as many as 2,500 fibrous strands fed simultaneously with the limit typically being space, demand and cost not necessary a technological limitation.
The speed and tension is typically controlled outside of the components of the invention with speed being based on the rate of drawing fibrous strand through the inventive components and tension controlled by resistance on rollers prior to the inventive components. The tension and speed are not limited by the instant invention with the exception of the necessity for some residence time in various components which is a function of power, as in the discharge device or ultrasonic treatment element, however the residence time under treatment can be increased by slower transit, by increasing the number of rollers in the treatment zone or by increasing the size of the treatment zone wherein the treatment zone is that region within which the treatment is occurring. The residence time under treatment can be decreased by faster transit, by decreasing the number of rollers in the treatment zone and therefore decreasing the path or by decreasing the size of the treatment zone. As would be realized to those of skill in the art each element of the inventive process can optimized using conventional engineering principles.
A particular feature of the invention is the ability of the coating to adhere to the fibrous strand. Without being limited by theory, it is hypothesized that the thermoplastic polymer and coating enter into the gaps of the fibrous strand. Once cured, the thermoplastic polymer has a mechanical advantage which exceeds that associated with coating alone. The result is an encapsulated fibrous strand wherein each filament of the fibrous strand is encased in cured thermoplastic polymer in a core-shell configuration.
An embodiment of the invention is illustrated schematically in cross-sectional view in
In some embodiments the superstructure assemblies or shapes are dried and conditioned with heat, steam, both heat and steam, or other methods.
A range of single superstructure assemblies or shapes from 600 meters to 20,000 meters or more in length would be taken from a reel, or a plurality of fibrous strands up to 2,500 or more at a time would be taken from a warp beam and is lead into an adjustable comb designed to ensure that the fibrous strands are closely aligned and not tangled or crossed with a preferred spacing of about 1 nanometer to about 10 micrometers.
The fibrous strands would then be drawn through a plasma treatment element at an energy of up to 6 kW followed by being drawn through a surfactant bath of about 100 liters to about 1000 liters containing anionic, cationic, or acidic surfactants mediated by ultrasonic energy of 0 to 3 KW forming a treated fibrous strand. This electrochemical process would enhance and expand surface gaps in the fibrous strands that are better able to hold coating materials in further processes.
The treated fibrous strand would be drawn through a series of sinusoidal rollers in an ultrasonic treatment element with a total length of more than 75 meters thereby permitting improved penetration to form a wetted fibrous strand.
A mix of coating material and thermoplastic polymer would be applied to the surface of the wetted fibrous strand under a specific pressure and speed thereby ensuring that the entire surface of the materials are coated with the appropriate material to impart pigment, bacterial resistance, temperature resistance, strength enhancement, luminosity, reflectivity, or environmental performance, water resistance or other properties as desired. The fibrous strands would then be exposed to a curing process to ensure the coating is fully complete.
A fixing coating would be applied thereby providing protection from oxidation, abrasion, and other potential insults to the fibrous strands.
The advent of super-tall buildings such as Burj Khalifa in Dubai, which is 828 meters (2,716 feet) in height) or Shanghai Tower in Shanghai which is 632 meters (2,703 feet) in height, traditional steel hoist cables, such as elevator hoist cables or “ropes”, are now highly engineered and made of steel with other composites. They are not single wires but several strands of various sizes wrapped together. A typical cable or rope can have over 150 strands of wire precisely designed to be strong, flexible, and provide long service. Multiple wire strands are used to increase the life of the cable and give it flexibility but these cannot be used for high speed elevators or in lifts used for moving passengers and freight. Traditional steel cables have a length limitation of about 500 meters (1,640 feet) because at that length the hoist rope weight and sheave, or pulley, shaft load on the hoist motor becomes untenable. The solution to the plus-500 meter problem; particularly in the Middle East, EU, and USA; has been the use of flat carbon tapes in place of steel hoist ropes. In Asia there have been instances of round carbon fiber superstructures being used. Flat carbon tapes can serve up to a kilometer in length, weigh 90% less, reduce energy consumption, reduce noise or “humming” in the hoist way, and they have a much longer life. However, unlike steel hoist ropes, wear and damage are harder to diagnose, and all four sides of the tape have to be examined. Typical flat carbon tapes used for hoist applications are 250 millimeters (˜10 inches) wide by 50 millimeters (˜2 inches) thick and up to 2,500 meters (8,200 feet) long. The material is typically treated with a protective polyurethane coating to provide a level of lubrication and protection for the flat carbon tapes.
Safety is a key certification requirement for elevators and lifts, and steel hoist ropes have an inspection protocol that has been in place since the mid-1870's. A nascent protocol for flat carbon tapes has been developed, but requires further refinement. The present invention provides a replacement for the standard polyurethane coating step associated with flat carbon tapes with a colored protective coating. The colored protective coating is designed to accomplish three objectives: First, to differentiate flat carbon tape lengths by color. Second, to use the abrasion characteristics of the colored protective coating as an inspection tool. As the color wears, inspection becomes much easier (less visible color means more wear or damage) and can be accomplished through computer vision. Third, the use of the present invention provides needed lubrication with hoist sheaves.
As a demonstration of the invention, a manufactured and fully thermoset single flat carbon tape of 250 millimeters (˜10 inches) in width, 50 millimeters (˜2 inches) in thickness, and 1,000 meters in length (3,280 feet), would be presented on a specialized reel for protective color coating and then reloaded on a specialized reel.
Superstructure assemblies and shapes would be coated with the continuous process technology where a colored protective coating would be transferred from a unique aero-diffusion system without the use of traditional processing equipment, hazardous chemicals, or large amounts of energy.
A length of single flat carbon tape from about 1,000 meters (3,280 feet) in length would be taken from a specialized reel.
The flat carbon tape would be moved over an AC electrode from 3 to 100 meters per minute providing a Corona Plasma Discharge up to 6 Kw making the flat carbon tape more electrochemically adhesive or sticky.
The top flat carbon tape would receive a coating material of 1 nanometer to 5 nanometers applied to the flat carbon tape under a specific pressure of about 0.5 Megapascal to about 1.5 Megapascal and a speed of 3 meters per minute to 100 meters per minute. The flat carbon tape would then be inverted by 180 degrees after the coating process to expose the bottom or untreated side.
The bottom of the superstructure assemblies or shapes would enter a duplicate enclosure for application of the coating material and thermoplastic polymer on the opposite side under a specific pressure and speed to ensure that the entire surface of the flat carbon tape is coated with the appropriate material designed to imparting color and wear or abrade at a respecified rate. The flat carbon tape would then be exposed to a curing process to ensure the coating is fully complete.
A final processing stage would apply a binder coating to the flat carbon tape. The binder coating would seal the coating thereby providing additional protection and designed.
The flat carbon tape, up to 1,000 meters (3,280 feet) in length, would be taken from the process and placed on a specialized reel.
The invention has been described with reference to preferred embodiments without limit thereto. One of skill in the art would realize additional embodiments which are described and set forth in the claims appended hereto.
