Patent Application
20110094691
The present invention is generally in the field of regeneration of post-consumer and post-industrial fibers.
Roughly a hundred billion pounds of post-industrial waste are landfilled or incinerated each year. While there are processes for recycling or regenerating these materials, such process traditionally provide materials used in lower value products such as carpet padding, automotive acoustic panels, and other items not visually impacted by a “shoddy fiber” technology. While these are good uses for pre or post industrial waste streams, consumers want more sustainable products in their everyday lives. The area of non-wovens, such as personal care products and household wipes, is a rapidly growing industry. There would be a tremendous value associated with using fibers which have been repurposed through a regeneration process into such non-woven products, instead of using virgin materials. This is particularly true for disposable products. The same is true of fibers that are spun into thread or yarn, and used to produce fabrics and other woven products.
Fibers that have been re-purposed using fiber regeneration technology could potentially offer a better product, at a cost advantage, resulting in an overall sustainable product that is good for the planet, consumers, and producers alike. It is important to understand the difference between traditional recycling and regeneration of textile or other waste streams. Recycling of textile or other fibers use equipment that is well known in the trade of “shoddy” fibers. This equipment when used takes textile waste and creates a shorter, weaker and damaged fiber. The process that we are talking about in this methodology is one that takes post consumer or post industrial “waste streams” and preserves the integrity of the strength and the length of the fibers so that they can be taken back to their original use or blended with other materials and enhance the characteristics of their original use.
It would be advantageous to provide new processes for regenerating and reusing the fibers present in post-consumer and/or post-industrial waste. The present invention provides such processes, as well as products prepared using the processes.
A process for upcycling and transforming waste materials into value added consumer products is disclosed. The process adds characteristics of the material that could not be otherwise afforded using traditional virgin components, and which are aesthetically pleasing and offer value to a quality consumer product.
The process uses traditional fiber-handling equipment, but makes specialized and unique changes to create environmentally-sustaining products. In one embodiment, the process provides regenerated fibers that closely match virgin fibers, and which are obtained at a cost that is significantly less than the cost of producing virgin fibers.
The process can use post-industrial or post-consumer waste streams as feedstocks. The waste streams include fiber-containing materials, and the fibers can be isolated from the waste streams and regenerated in order to achieve maximum benefit from the fiber lengths, strengths, and other properties. The fibers can then be efficiently processed through traditional or modified woven or non-woven processes into finished roll goods. The finished roll goods can then be converted into a variety of consumer products.
The process described herein takes us several steps forward relative to other processes, in that it eliminates soft threads and individualizes the fibers, and due to this new process, it can be used to regenerate and upcycle to transform the hundreds of millions of pounds of waste that would have otherwise found its way to a landfill or incinerator.
The process creates products that are superior in certain qualities and characteristics to those made from virgin materials, typically at less cost, or in a cost competitive manner relative to processes using virgin materials. Thus, the process can reduce the carbon footprint associated with producing the products, reduce water usage, and reduce the use of chemicals by greater than 90% relative to processes using virgin materials, thus creating a true sustainable product and process.
Representative post industrial or post consumer waste streams that can be used as feedstocks include fabrics such as knits, for example, t-shirts, socks, undergarments; wovens, from items such as shirting, sheeting, bottom weight, denim, bedding, and upholstery; and non-wovens. These materials can be bleached white, or optically brightened or dyed fabrics, and can be used to increase value and reduce cost by using the materials as they are to create a higher valued product without using additional bleaches or dye baths to achieve the same results. Dyed Cotton fibers or yarns are more expensive and take additional chemicals and waste water which increases the carbon output, chemicals and water usage, but these regenerated fibers have either been thru bleaching, optical brightening or dyeing processes and therefore to achieve the same final results to not have to be bleached, optically brightened or dyed and can have a better cost basis for the manufacturer and the same or better aesthetic value for the consumer. For example, a baby wipe can be made with regenerated cotton from knits and wovens, where the cotton is already white, so no bleaching or optical brighteners are necessary to add to this process. At the same time, creating a non-woven out of a colored fiber waste stream, such as denim, can result in a pale blue wiping cloth perfect for industrial or household non-wovens, without the need for additional dyes or colorants, to create a value added product for the consumer product arena. The use of black fibers from black t-shirt waste streams can result in marl yarns which are the most expensive yarns in the industry and this is a product that is inexpensively, reduces carbon footprint, water and chemical usage by up to 90% and is a consumer's preferred choice.
In this process, to create a total value stream, it is advantageous to realize that all (i.e., 100%) of the fiber lengths created in this process can be used to create value added products. The example above of the baby wipe is created from a median fiber length of typically 0.50-0.95 while the longer fiber that is derived from this process can go back to creating yarns of the same count and strength that the original garments virgin material was made from. For example, the trim from a t-shirt manufacturer can be regenerated and upcycled to create yarn and knitted fabric to go back into a t-shirt of equal quality.
In this process, to create a total value stream, it can be advantageous to realize that all (100%) of the fiber lengths created in this process can be used to create value added products. The example above of the baby wipe is created from a median fiber length of typically 0.50-0.95 inches, while longer fibers derived from this process can used to create yarns of the same count and strength that the original garments virgin material was made from. For example, the trim from a t-shirt manufacturer can be regenerated and upcycled to create yarn and knitted fabric to go back into a t-shirt of equal quality.
These materials typically include fibers that are either 100% cotton, or blends of cotton and various other fibers, such as polyester, viscose, rayon, lyocel, nylon, bamboo, polyolefins, and the like.
The process can also incorporate other fibers, including natural and synthetic fibers, such as fibers from seeds, stalks, basts, stems, leaves, or fruits, fibers derived from animal hair, and silk fibers or other protein based fibers. The other fibers can be transformed natural fibers (i.e., cellulose derivatives), and wholly-synthetic fibers. The other fibers can also include inorganic fibers, such as glass fibers and metal fibers.
At least a portion of the fibers are isolated from post-industrial or post-consumer waste. To isolate fibers from these materials, which are previously woven, knitted, or bonded together by a non-wovens process, it is necessary to un-weave or un-twist the threads. This can be accomplished, for example, by removing post-treatments from the threads, which thins the threads and loosens the knots or twists. In the case of cellulosic fibers, a portion of the cellulosic fiber can be degraded, for example, using a cellulose enzyme. Once the threads are unwoven/untwisted, the fibers are obtained by combing the thread, which produces fibers that have maintained the length and the strength necessary to go back to textiles or, in this embodiment, non-wovens.
Before going into woven or non-woven materials, it can be advantageous to pass the fibers through one or more stages of “intimate blending,” so that the fiber distribution is relatively homogeneous. The term “relatively homogeneous” is used to mean that the average fiber size and density varies by 20% or less throughout the fiber. The intimate blending can also provide color uniformity, which can otherwise be difficult to attain when different batches of fibers are used to produce a single non-woven fabric.
Intimate blending involves initially humidifying or treating the fibers, which strengthens the fibers, if they are organic fibers such as cotton, cotton blends or fibers such as rayon or ramie, reduces dust particles for better product performance and, protecting the fibers from tensile elongation, and reduces neps. The fibers can be humidified, for example, by exposing them to steam, contacting them with a hydrophilic compound such as glycerol/glycerine, a surfactant, water, and the like. Ideally, the humidified fibers have a moisture content of between 8 and 20% moisture, more ideally, between about 8 and about 12% moisture. Then, the fibers can be passed through one or more blending stages, where samples from multiple hoppers are blended together to reduce variation between the fibers in the hoppers, or where samples from a single hopper are blended to ensure consistency in the hopper or it could be blended using a traditional cotton/fiber laydown where bales are staged for blending. Multiple hoppers can be used, for example, where blends of different fibers are intended. Examples include using regenerated cotton fibers in combination with one or more virgin or regenerated plant fibers, such as wood, kenaf, and the like, or synthetic fibers, such as polyester or polyolefin fibers. However, the regenerated cotton fibers can be used by themselves, without adding other fibers.
The fibers at this stage in the process are randomly oriented, but can optionally be oriented using a non-woven or textile carding process.
The fibers can be subjected to one or more chemical treatments, Representative treatments include humidification, the addition of surfactants to provide more hydrophilic products, which can be important when the fibers are used to prepare wipes or other substrates used in aqueous solutions, or when the fibers are used in substrates needing to be used to absorb liquids. Other such treatments include treatment with starch, glycol/glycerin, antimicrobial agents, such as cationic polymers/cationic latex, silicones, fluorinated agents which provide the fibers and resulting materials formed from the fibers with anti-stain protection, and the like. These treatments can occur after the fabric has been formed, or before the fibers are formed into thread and knitted, and/or mechanically/thermally/chemically bonded in non-woven processes.
In one embodiment, the randomly-oriented, intimately blended fibers are subjected to a carding process to form a uniform fiber web. Such a uniform fiber web is typically passed, over a conveyor belt or a web, where it can optionally be combined with one or more layers of fibers or webs of fibers.
The regenerated fibers can be used in processes where they are layered with one or more layers of fibers that are different fibers than the regenerated fibers. The additional one or more layers can comprise randomly-oriented fibers, for example, laid down in an air-laid process over the top of the oriented fiber web, and, optionally, a further oriented fiber web can be laid on top of the randomly-oriented fibers.
In another embodiment, these fibers can be taken from the baled stock produced after the regeneration process, entered into a spinning mill either on the “lay down” of cotton in the blow room or placed into the textile mill thru a blending hopper and metered feeding system thru the carding process to create sliver and then continued down the mill floor to be spun into high quality yarns that maintain all efficiencies of virgin fibers. These can be used at 100% regenerated fibers or a blend of virgin cotton or other textile related fibers such as rayon, lyocel, polyester and the like.
In other embodiments, the regenerated fibers are combined with polyolefin or other thermoplastic fibers, so that the fibers can be bonded in a thermal fashion, rather than a chemical or mechanical fashion, when used in non-woven applications. In this embodiment, the thermoplastic fibers are typically present in a concentration of at least around 5% w/w.
In one embodiment, a cationic wet-strength resin is applied to the fibers, for example, via dipping, spraying, and the like, to impart additional strength to the fibers, for example, when they are used in wet-laid applications to form wipes or other products.
The regenerated fibers can find use in a number of end-products, including knits, woven and non-woven products. Woven products include textiles, rugs, apparel, and the like. Examples of some of the potential non-woven products include, but are not limited to, hygiene products, medical products, filters, geotextiles, and other products, and specifically include wipes. The wipes can be adapted to include a variety of additional components, including moisturizers, cleansers, essential oils, antibacterials, antivirals, antimicrobial cationic polymers, and the like.
The regeneration process is described in detail below. The process described herein generally involves recovering fibers from post-industrial or post-consumer waste, optionally blending those fibers with other fibers, optionally subjecting the fibers to an “intimate blending” step to provide a uniform blend of fibers. The fibers can then be subjected to a carding process to orient the fibers. Optionally, the fibers can be subjected to one or more chemical treatments, and can be spun into yarn or thread, and used to make woven products, or used directly in non-woven products. Each of the process steps is described in more detail below.
The present invention will be better understood with reference to the following definitions:
As described in more detail herein, fibers are formed into a web using a variety of processes, which include techniques for a) orienting or not orienting the fibers, b) laying the fibers down to form a web, and c) bonding the fibers in the web to form a non-woven material. Carding processes are typically used to orient the fibers. The fibers can be laid down on a moving conveyor belt using a variety of techniques, including direct carding lay, air carding, air lay, wet lay, and the like. The laid-down fibers can then be bonded using one or more of mechanical, chemical, or thermal bonding techniques. Terms of art in connection with the laying down of fibers, and the bonding of the laid-down fibers, are defined below.
Textile Yarns
Yarn is defined herein as a long continuous length of interlocked fibers, suitable for use in the production of textiles, sewing, knitting, weaving and ropemaking. Yarn can be made from any number of synthetic or natural fibers. Very thin yarn is referred to as thread. Yarns are made up of any number of plys, each ply being a single thread, with these threads being twisted (plied) together to make the final yarn.
Textile Fabrics:
As used herein, a “textile fabric” refers to any material made through weaving, knitting, crocheting, or bonding. The term “cloth” refers to a finished piece of fabric that can be used for a purpose, such as covering a bed.
Non-Woven Fabric
As used herein, a “non-woven fabric” is defined as a fabric made directly from a web of fiber, without the yarn preparation necessary for weaving and knitting. In a non-woven, the assembly of textile fibers is held together 1) by mechanical interlocking in a random web or mat; 2) by fusing of the fibers, as in the case of thermoplastic fibers; or 3) by bonding with a cementing medium such as starch, casein, rubber latex, a cellulose derivative or synthetic resin. Initially, the fibers may be oriented in one direction or may be deposited in a random manner. This web or sheet is then bonded together using a variety of methods, which are described in detail below.
Various techniques can be used to prepare the initial assembly of textile fibers, including air carding, direct lay carding, air lay, and wet lay.
Carding
As used herein, “carding” is a mechanical process that breaks up locks and unorganized clumps of fiber, and then aligns the individual fibers so that they are more or less parallel with each other. These ordered fibers can then be passed on to other processes that are specific to the desired end use of the fiber. Carding can also be used to create blends of different fibers or different colors. When blending, the carding process combines the different fibers into a substantially homogeneous mix. Commercial cards commonly have rollers, and may optionally have systems in place to remove various contaminants from the fibers.
Commercial carding machines allow the “carded” fiber to pass through the workings of the carder for storage or for additional processing by other machines. A typical carder has a single large drum (called the “swift”) accompanied by a pair of in-feed rollers (“nippers”), one or more pairs of worker and stripper rollers, a “fancy,” and a “doffer.” In-feed to the carder is usually accomplished by conveyor belt, and often the output of the carder can either be stored as a batt, or further processed into the non-woven material described herein by mechanically, chemically, or thermally bonding the fibers together. A representative carder is shown in
As swift (10) carries the fibers forward from the nippers (30), those fibers that are not yet straightened are picked up by a worker (40) and carried over the top to its paired stripper (20). Relative to the surface speed of the swift (10), the worker (40) turns quite slowly. This has the effect of reversing the fiber. The stripper (20), which turns at a higher speed than the worker (40), pulls fibers from the worker (40) and passes them to the swift (10). The stripper's relative surface speed is slower than the swift's, so the swift (10) pulls the fibers from the stripper (20) for additional straightening.
Straightened fibers are carried by the swift (10) to the fancy (50). The fancy's card cloth is designed to engage with the swift's card cloth so that the fibers are lifted to the tips of the swift's card cloth and carried by the swift (10) to the doffer (60). The fancy (50) and the swift (10) are the only rollers in the carding process that actually touch.
The slowly turning doffer (60) removes the fibers from the swift (10) and carries them to a fly comb (not shown) where they are stripped from the doffer. A fine web of more or less parallel fiber, a few fibers thick and as wide as the carder's rollers, exits the carder at the fly comb by gravity or other mechanical means. The web can then be stored, or further processes into a non-woven material using the additional process steps described herein.
A carder typically includes a “card cloth.” A card cloth is made from a sturdy rubber backing, in which closely-spaced wire pins are embedded. The shape, length, diameter, and spacing of these wire pins is dictated by the card designer and the particular requirements of the application where the card cloth will be used.
Card Room
The carding step is typically conducted in a room, called a “card room,” which is set up to handle the carding equipment, and also to provide the appropriate temperature and pressure for the fibers, in order to maintain their length and strength throughout the carding process.
Moisture Requirements:
In order to maintain the length and strength of the fibers, it is preferred to control the moisture content of the fibers as they are carried out through the various process steps. Ambient temperature (i.e., around 75° F.) is ideal, and a relative humidity of around 65% is also ideal, although these can vary, according to each individual non-woven product being created, and the ranges of regenerated fibers in each product.
In one embodiment, the product includes relatively high percentages of regenerated cotton fibers, and therefore requires relatively higher humidity. The ranges of temperature and humidity are ideally within the following parameters: temperature between 62 and 98° F. and relative humidity between 40 and 90 percent.
Modification of Textile Carding and Spinning Equipment
While the fibers have the length and strength requirements found in natural virgin fibers, there can be dust associated with the fibers that are a bit smaller than that of traditional fibers therefore modifications must be considered in further carding, drawing, roving and spinning equipment. It is typical in this process that additional cleaning, with light suction points throughout the equipment, can be used to maximize the performance of these fibers.
Filtration Points in Non-Woven Web-Forming Equipment
Due to the short staple that is inherent in regenerated fibers, there may be dust particles that accompany the fiber throughout the regeneration process. In order to efficiently use regenerated fibers, it can be desirable to remove the dust particles. One way to do this is to modify traditional equipment running synthetic fibers, so that the dust particles are removed, and the regenerated cotton fiber can be run at around the same efficiencies as that of synthetics. If the dust particles are not removed, the dusting can cause problems with equipment, such as shut downs or overheating.
One such modification involves placing “suction points” throughout the carding equipment to insure cleanliness of motors, drives, web formation, and the like. These “suction points” can remove the dust, and eliminate or minimize the problems associated with dust particles.
Card Wire Specification: If a non-woven card is used in the process of web formation, it can be important that the proper metallic toothwire is used that is specific to the raw material requirements. In one embodiment, the issue relates to the ability to successfully manufacture a non-woven product with high percentages of regenerated cotton. When seeking to regenerate cotton fiber, it can be advantageous to use a metallic toothwire that is specific to use with cotton fibers. For example, while there are many producers of wire specific to cotton, JD Hollingsworth is a manufacturer of card clothing that has a number of patents around the appropriate wire for cotton. While they focused their research on virgin cotton, the points on the wire are similar, since the regeneration of the fiber returns the cotton back to its original lengths and strengths.
The points are thus relevant to forming the highest quality regenerated fibers, and the use of the appropriate points is a preference in the manufacturing of a high regenerated cotton product as this embodiment describes. It is not always necessary to use a card clothing/wire specific to cotton, but it is preferred. There are other wires specific to synthetics, and these have a much broader range of options.
In one embodiment, the regenerated fibers are recovered and regenerated from fabrics such as knits, including t-shirts, socks, and undergarments; wovens, including items such as shirting, sheeting, bottom weight, denim, bedding, and upholstery; and non-wovens.
These fibers typically include one or more of the following: 100% cotton, cotton blends, such as cotton/polyester, cotton/viscose, cotton/lycra, cotton/ramie, cotton/nylon, and the like, viscose/rayon, polyester, polypropylene or other polyolefins, nylon or other polyamides, and ramie.
II. Additional Fibers that can be Added
In addition to the fibers described above, other fibers can also be used. Representative other fibers include natural, organic, and synthetic fibers.
Natural fibers include those from various plants/vegetables. Examples of fibers derived from seeds include cotton and kapok (KP).
Examples of fibers derived from basts or stems include wood, flax, linen (LI), hemp (HA), sunn hemp (SN), jute (JU), ramie (RA), kenaf (KE), straw (STR), banana (BAN), pineapple (PIN), papyrus (PAPY), alfagras/esparto (AL), fique/Mauritius Fiber (FI), alginate (ALG), urena/Congo Jute (JR)), nettle (NTL), broom (GI), apocynum (APO), raffia (RAF), and natural bamboo (BAM).
Examples of fibers derived from leaves include sisal (SI), abaca/Manila (AB), henequen (HE), phormium/New Zealand Fiber (NF), acacia (AKAZ), aloe (ALO), yucca (YUCC), and elephant grass (ELEG).
Examples of fibers derived from fruit include coir/coconut (CC).
Animal fibers include wool and other animal hair (WO), silk (SE), and wild silk/Tussah (ST).
The fibers can be formed by various transformations of natural fibers, for example, regenerated cellulose & cellulose esters such as viscose (CV), bamboo regenerated (CBAM), modal (CMD), lyocell (CLY), acetate (CA), and tri-acetate (CTA).
Examples of proteinaceous fibers derived from plants include peanut (PEA), corn (COR), soybean (SPF), alginate (ALG), milk (CS), and polylactic Acid (PLA).
Examples of fibers formed from synthetic polymers include polyamides, such as Polyamide 4.6 (PA 4.6), Polyamide 6 (PA 6), Polyamide 6.6 (PA 6.6), Polyamide 6.10 (PA 6.10), Polyamide 6.12 (PA 6.12), Polyamide 11 (PA 11), Polyamide 12 (PA 12), and Polyamide-imide (PAI). Also included are polyesters, such as polyethylene terephthalate (PET), poly cyclohexane-dimethanol terephthalate (PCT), polytrimethylene terephthalate (PTT), polybutylene Terephthalate (PBT), polyestermide (PETI), and polybeta hydroxybutyrate (PHB). Representative polymers also include polyurethanes (PU), including polyuretherthane (PUR), elasthane (EL), and elastodiene (ED). Also included are polyvinyl compounds, including polyvinyl chloride (CLF), polyvinylidene fluoride (PVDF), polyvinylidene chloride (PVDC), polyvinyl alcohol (PVA), polyvinyl acetate (PVAC), and ethlyene vinyl acetate (EVA). Polyolefinic fibers include polyethylene (PE) and polypropylene (PP). Some of these fibers are fluorinated, such as polyteteafluorethylene (PTFE), ethylene chlorotrifluorethylene (ECTFE), polychlorotrifluoroethylene (PCTFE), perfluoroalkoxy (PFA), and polyvinyl fluoride (PVF). Other synthetic fibers include meta-aramid (m-AR), para-aramid (p-AR), melamine formaldehyde (MF), polybenzimidazole (PBI), polycarbonate (PC), polyetheretherketone (PEEK), polyether-imide (PEI), polyetherketone (PEK), polyethersulfone (PES), polyethyleneaphtalate (PEN), polyimide (PI), polymethyl methacrylate (PMMA), polyoxymethylene or polyacetal (POM), polyphenylene oxide (PPO), polyphenylenesulfide (PPS), polystyrene (PS), and polysulfone (PSU).
Some fibers are inorganic in nature. Representative inorganic fibers include glass fiber (GF), silicic acid glass (GFS), carbon fiber (CF), ceramic fiber (CEF), metallic fibers (MTF), steel (STL), inox (INX), copper (CU), and basalt (CBF).
Representative Fiber Lengths
In the world of regenerated fibers, there are typically three lengths that are considered. The longer length is best used in carded applications, medium length fibers used in both carded and air laid applications, and short fibers are more specific to air laid or wet lay processes. Fiber lengths can range from 50 microns to up to 6 inches or more for crimped or non-crimped fibers.
For both the regenerated fibers (isolated from post consumer and/or post-industrial waste), and the other fibers, suitable fiber lengths and distribution can vary from fibers as small as 250 microns to fibers up to 6 inches, based on the delivery mechanism.
An example of lengths of fibers necessary to a wet laid application would be 250 microns to 13 mm, where the fiber lengths in a dry direct lay application would vary from 0.50 median lengths up to 3 inches.
In one embodiment, the fibers are regenerated cotton fibers, with a size range between about 250 microns to about 8 mm for wet laid applications, and between about half inch and about 1.30 inches for dry direct lay or a combination of direct lay and air carding application.
For example, where a “direct lay with air card for randomization” approach is used, the range is most effective between about 2 mm inch and about 1.30 inch. The ranges for the fibers depend, at least in part, on the desired application for the non-woven material.
When regenerated fibers are used in combination with other fibers, the regenerated fibers are preferably present in a concentration of between about 2 and about 98%, and the other fibers are preferably present in an a concentration of between about 1 and about 88%, based on the total weight of the fibers. In one embodiment, the blend of regenerated fibers and other fibers is a 95/5 blend by weight. In another embodiment, the blend of regenerated fibers and other fibers is a 90/10 blend, a 85/15 blend, and 80/20 blend, and 75/25 blend or 50/50 blend. In these blends, the other fibers can include any of the other fibers described herein, in any desirable combination.
III. Process for Isolating Fibers from Post-Consumer or Post-Industrial Waste
Ideally, the process for isolating fibers from post-consumer or post-industrial waste involves using needles to separate the previously-woven strands into the threads that comprised the fabric to begin with. As this is difficult to do with the entire scrap material, it is advantageous to cut the scrap into a more manageable size (i.e., a uniform 2″ by 2″, 4″ by 4″, or other suitable size). It can also help to work from the ends of the scrap material, rather than the middle of the scrap material.
In some embodiments, the fibers are cellulosic fibers. It can be advantageous to slightly degrade the fibers, so that they are not as tightly knitted or woven. That is, by degrading a portion of the cellulose, the knots open up slightly, making it easier to unravel the knots and obtain the free threads.
Cellulose fibers can be degraded by contacting them with various enzymes, which enzymes include cellulases. One or a combination of such enzymes can be used. Cellulosic and other fibers typically have one or more post-treatments on them, which thicken the fibers. Enzymatic or chemical processes can be used to remove the post-treatments, thus thinning the fibers and loosening the knots or weaving.
Contact times and temperatures for the enzymatic or chemical processes can be determined using ordinary skill, for example, by monitoring the partially-degraded material to determine the optimum point in time where the threads are loosened enough to un-knit them, but not so much that a significant loss of material is observed. Ideally, the temperature is between 120 and 180° C., although these reactions can also occur at lower temperatures, such as room temperature.
After the threads are un-knitted, loose threads can be stored for later use. In some embodiments, it can be useful to remove any dyes from the threads, so that the threads resemble virgin material.
In order to process the threads into a non-woven material, it can be advantageous to “fluff” the threads into a lower density material, where the density is reduced relative to the original fibers, or clumps of fibers, obtained from the de-knitting process. Fluffing is generally accomplished using a mechanical combing and/or picking action, which selects smaller quantities of threads from the whole, and the combing and/or picking action breaks the threads down into lint or individual fibers.
The fibers or lint produced in the fluffing step are in random orientation, and in certain non-woven applications, it is desired to orient the fibers in a single direction. This can be accomplished, for example, using a modified carding operation. In a modified carding operation, a series of cylinders are used, where a comb is aligned with the cylinders. The fluffed fibers are passed over the cylinders, in contact with a plurality of combs, which orient the fibers. Once the fibers are oriented, they are suitable for use in preparing non-woven materials, particularly where the oriented fibers are intended to be mechanically interwoven, such as with a spun-lace process.
To isolate fibers from these materials, which are previously woven, knitted, or bonded together by a non-wovens process, it is necessary to un-weave or un-twist the threads. This can be accomplished, for example, by removing post-treatments from the threads, which thins the threads and loosens the knots or twists.
In the case of cellulosic fibers, a portion of the cellulosic fiber can be degraded, for example, using a cellulose enzyme, and such enzymes are known in the art, and sold, for example, by companies such as Iogen and Novozymes.
Once the threads are unwoven/untwisted, the fibers are obtained by combing the thread, which produces fibers that have maintained the length and the strength necessary to go back to textiles or, in this embodiment, non-wovens.
Before going into textiles or non-wovens, it can be advantageous to pass the fibers through one or more stages of “intimate blending,” so that the fiber distribution is relatively homogeneous. The terms “relatively homogeneous” or “substantially homogeneous” are used to mean that the average fiber size and density varies by 20% or less throughout the fiber. The intimate blending can also provide color uniformity, which can otherwise be difficult to attain when different batches of fibers are used to produce a single non-woven fabric.
In one embodiment, the fibers are subjected to an intimate blending process step. Intimate fiber blends are described herein as substantially homogeneous blends of fiber(s) that distribute the different lengths or different combinations of the fiber(s) evenly throughout the batch of fiber. The regenerated cotton non-woven fabric described herein is ideally prepared using intimate blending, to ensure homogeneous fiber distribution, due to the broad range of fiber lengths found in regenerated fibers. It is also ideally prepared using fiber humidification to maintain the strength of the fiber throughout the process, as well as using suction points and/or a filtration system to keep the equipment running efficiently, by removing dust particles and the like.
This intimate blending can contribute to the beneficial properties of the regenerated fiber substrate. The fiber distribution in regenerated textiles can be varied, and, accordingly, intimate blending of the resulting fibers can be performed, whether the fibers are used alone or as blends with other types of fibers, prior to entanglement or fusion. The use of other fibers is optional, and depends on the desired application of the resulting non-woven fabric.
Intimate blending involves initially humidifying or treating the fibers, which strengthens the fibers, if they are organic fibers such as cotton, cotton blends or fibers such as rayon or ramie, reduces dust particles for better product performance and, protecting the fibers from tensile elongation, and reduces neps.
The fibers can be humidified, for example, by exposing them to steam, contacting them with a hydrophilic compound such as glycerol/glycerine, a surfactant, water, and the like. Ideally, the humidified fibers have a moisture content of between 8 and 20% moisture, more ideally, between about 8 and about 12% moisture. Then, the fibers can be passed through one or more blending stages, where samples from multiple hoppers are blended together to reduce variation between the fibers in the hoppers, or where samples from a single hopper are blended to ensure consistency in the hopper or it could be blended using a traditional cotton/fiber laydown where bales are staged for blending. Multiple hoppers can be used, for example, where blends of different fibers are intended. Examples include using regenerated cotton fibers in combination with one or more virgin or regenerated plant fibers, such as wood, kenaf, and the like, or synthetic fibers, such as polyester or polyolefin fibers. However, the regenerated cotton fibers can be used by themselves, without adding other fibers.
The following is a general process for intimately blending fibers, though not every step needs to be carried out exactly as described below, so long as the resulting fiber distribution is substantially uniform.
Bales of regenerated fiber are taken and put into large storage hoppers based on each individual fiber type. If the blend is 100% of one fiber, then the hoppers deliver by weigh pan methods exactly or substantially the same percentage of fiber out of each hopper. If the percentages of each fiber are different, then the bales are put into the hoppers, and, using weigh pan technology, the fiber is delivered onto a belt with each “group” of fibers being laid on top of one another.
The “groups” of fiber are then put into a “fine opening” process, which carefully blends the fibers together and deposits them to the next stage of blending, which begins with a large storage hopper. In one embodiment, the hopper holds up to 40,000 lbs of fiber.
As the fiber passes through the air into the box, this provides another opportunity to blend the fibers, and also affords the opportunity to provide additional humidification or fiber treatments.
When the storage hopper is full or substantially full, the fibers can then be picked, for example, using a sandwich-like approach where the fibers are laid down horizontally into the blending hopper in layers then vertically picked up from the bottom to the top of the hopper, using a spiked apron and a moving floor, and put into yet another fine opener which takes the fibers delivered from the blending hopper and gently opens and fluffs the fibers before delivering the fibers to be baled for further processing, or directly into the specific application used to deliver the fibers to their entanglement or fusion process.
Carding
After the fibers are intimately mixed, a card wire can be used to open and gently align the fibers, to maintain a consistent web appearance. When the fibers are regenerated cotton fibers, or predominantly so (i.e., greater than about 50% regenerated cotton fibers, or regenerated and virgin cotton fibers), the resulting web has using the unique look and feel of cotton. The carding process can also be used in those embodiments where intimate mixing is not performed, before the non-woven web is produced.
Ideally, to ensure that the cotton fibers maintain their length and strength during the regeneration process, and to maximize regenerated cotton fiber processability, the fibers are humidified. In one embodiment, cotton fibers are delivered to the blending process with no less than 8%, but no greater than 25%, moisture content. This moisture level increases the fiber strength, and therefore preserves the fiber length.
It is also desirable to keep moisture levels in the fiber throughout the process, which can be done, for example, by adding humectants or other suitable materials (i.e., hydrophilic materials such as glycerol) to the fibers.
The moisture level throughout the process ideally does not drop below 5%, and in one embodiment, levels out to between 12 and 15% at the end of the process.
The fibers can also be subject to other fiber treatments, either before or after forming the fibers into a non-woven material. Representative fiber treatments include one or more of humidification, addition of surfactants to provide the fibers with greater hydrophilicity (for example, when the fibers are used for highly hydrophilic products, such as wipes or other substrates used in aqueous solutions or a substrate needing to be used to absorb liquids). Other representative treatments include, but are not limited to, starch, glycol/glycerin, antimicrobial treatments, silicone, fluorinated anti-stain treatments, addition of fire retardants, addition of cationic wet strength resins, and the like.
Representative wet strength resins include the cationic polyamide wet strength resins sold by Georgia Pacific® under the Amres® brand, and are typically supplied as aqueous solutions in a range of solids from 12.5% to 35%, and include Amres® 117, Amres® 12-HP, Amres® 135, Amres® 20-HP, Amres® 25-HP, Amres® 652, Amres® 653, Amres® 8855, Amres® 8860, Amres® 8870, Amres® HP-100, Amres® HS-30, Amres® MOC-3025, Amres® MOC-3066, Amres® PR-247HV, and Amres® PR-335 CU.
To form a non-woven sheets, which are typically then rolled to form a rolled good, one first orients the fibers in a desired manner, then lays the fibers down onto a conveyor belt to form a web, and then mechanically, chemically, or thermally bonds the fibers in the web. The fibers can be laid down using one or more processes as are well known in the art of non-wovens, including direct lay, wet-lay, and air-lay approaches.
In some embodiments, layers of webs formed from the fibers can be combined. For example, the non-woven material can include a) multiple carded webs, b) a direct carded layer on which an air laid layer and a second direct carded layer are applied, c) cross-lapped layers, and d) layers combined with a scrim.
By using these approaches, one can provide a regenerated cotton product with the MD/CD strengths that are gained from much longer synthetic fibers. By using one or more carding groups based on weight calculation of the desired product, one can add an air carded web that is a total randomization of fibers, creating MD/CD ratios of the most sought after 1-1 strength requirements.
By adding an air carded web in the center of three carding groups, the aesthetics are that of a complete carded web product, with the strength of synthetic fibers (particularly when the air carded web includes randomly oriented synthetic fibers), while still using the more desired sustainable cotton fibers (for example, in the direct laid top and bottom webs).
Cross-lapped products tends to be loftier than those produced using a direct-carded web, or even the above-described embodiment where a direct lay approach is used with an air card layer to a layer with provide randomized fiber orientation.
The addition of a scrim layer provides yet another way to increase MD/CD strength of a regenerated cotton web, where the added strength comes from the added scrim.
In any of these embodiments, the fibrous web can be bonded using known mechanical, chemical, or thermal bonding techniques. Mechanical bonding, which involves interlocking the fibers into a random web, mat, or sheet. Thermal bonding involves fusing the fibers, for example, by adding between 2 and 20% of a thermoplastic fiber, for example, a polyolefin (such as polypropylene) fiber. When heated, such as between calendar rolls, one can fuse the fibers together. Chemical bonding involves adding a cementing medium to the fibers, and chemically fusing the fibers together. Representative cementing media include starch, casein, rubber latex, cellulose derivatives, and synthetic resins. A hybrid chemical/mechanical approach that is occasionally used with cotton non-wovens is to treat the web with sodium hydroxide, to “shrink-bond” the web. The caustic causes the cellulose-based fibers to curl and shrink around one another as the bonding technique. This approach can be advantageously used with regenerated cotton fiber.
As discussed above, the fibers may be oriented in one direction or may be deposited in a random manner to form a web or sheet, using the various processes for laying down the fibers. This web or sheet can then be bonded together by one of the methods described above. The present invention is intended to encompass non-wovens prepared using random and/or oriented fibers, laid down with any of the above-mentioned techniques, and bonded using any of the above-mentioned techniques, in any combination.
Representative bonding methods include thermal bonding, using a large oven for curing, calendering through heated rollers (called spunbond when combined with spunlaid), wherein the calendars can be smooth faced for an overall bond or patterned for a softer, more tear resistant bond, hydro-entanglement (the mechanical intertwining of fibers by water jets, called “spunlace,” ultrasonic pattern bonding, often used in high-loft or fabric insulation/quilts/bedding, needlefelt (mechanical intertwining of fibers by needles, and chemical bonding (a wetlaid process involving the use of binders, such as latex emulsion or solution polymers, to chemically join the fibers). A more expensive route uses binder fibers or powders that soften and melt to hold other non-melting fibers together. Some of the non-woven fabrication methods that can be used to prepare the non-woven materials described herein are described in more detail below.
In any of the above-mentioned techniques, the resulting bonded web or mat is then either used directly to form finished goods, or can be rolled-up and stored for later conversion to finished goods.
VIII. Materials Formed from the Non-Woven Fabric
The non-woven materials produced using the methods described herein can be used in numerous applications, including hygiene products, medical products, filters, geotextiles, and other products. Representative hygiene products include baby diapers, feminine hygiene products, adult incontinence products, wipes, including anti-septic wipes, bandages and wound dressings. Representative medical products include isolation gowns, surgical gowns, surgical drapes and covers, surgical scrub suits, and caps. Representative filters include gasoline, oil and air filters, including HEPA filtration, water, coffee, and tea bags, liquid cartridges and bag filters, vacuum bags, allergen membranes, and laminates with non woven layers. Representative geotextiles include soil stabilizers and roadway underlayment, foundation stabilizers, erosion control, canals construction, drainage systems, geomeambranes protection, frost protection, agriculture mulch, pond and canal water barriers, and sand infiltration barriers for drainage tile. Other products include both primary and secondary carpet backing, composites, marine sail laminates, tablecover laminates, chopped strand mats, backing/stabilizer for machine embroidery, packaging—to sterilize medical products, insulation (fiberglass batting), pillows, cushions, and upholstery padding, batting in quilts or comforters, consumer and medical face masks, mailing envelopes, tarps, tenting and transportation (lumber, steel) wrapping, and disposable clothing (foot coverings, coveralls).
The production of the various materials described above from a non-woven fiber roll good can be done using methods well known to those of skill in the art.
When it is desired to convert the fibers into woven materials, the fibers are first converted to yarn or thread using spinning processes, as such as known in the art. There are many variables in a spinning mill, including the types of fibers to be spun, atmospheric conditions in the plant, type of machines, market requirements, and the like. Those of skill in the art can readily control these variables to produce a quality yarn or thread using the regenerated fibers described herein.
The yarn or thread spun from the regenerated fibers, or combinations of regenerated and other fibers, can be used to create woven fabrics, which can be used directly or can be stored for later use. The thread and yarn can optionally be dyed or bleached using conventional techniques, and treated with any of a variety of treatments to impart beneficial properties, as described above with respect to the fibers and the non-woven fiber rolls. The woven fabrics can be used to prepare any of a variety of textiles, clothing, and the like. The production of the various materials described above from a woven fabric can be done using methods well known to those of skill in the art.
In one embodiment, the regeneration process involves:
1. Collecting the raw material that is of consistent composition.
2. Cutting the waste raw material into manageable sizes to open the appropriate lengths desired by the end use application,
3. Using sword sharpened 1-4 inch pinning to separate the groups of threads from each other,
4. Using a chemical treatment, optionally using specific enzymes and specific fabric softeners to take off any “textile” finish that is created in the textile manufacturing process, ideally at a temperature above room temperature, but below the boiling point of water,
5. Allowing a residence time in the chemical treatment of at least 1-24 hours dependent on the end use application,
6. Removing the textile material from the residence area into multiple untwisting chambers, accompanied with steam application in each chamber to keep the fibers from becoming damaged by heat or lack of moisture, that delicately separate the threads to create a final product of soft twisted yarns that are comparable to that of virgin materials in their strength, length and ability to dye of re-finish in traditional textile applications.
The traditional method of re-cycling leaves fibers in a “shortened fiber” state along with twisted yarns that are commonly called out as shoddy fibers used in automotive insulation, under carpet padding, and other low quality applications. The finishing method that is described is used in combination with the regeneration technology described herein.
The regenerated fibers are prepared as described herein. Material is taken in the soft twist state and air conveyed into a traditional textile machine that has been re-engineered to comb the fibers in at least four different stages in the operation. The cylinders are different sizes, with different combing wires and pin applications, to create a finished product that is comparable to cleaned virgin fibers. The fiber lengths have now been increased from the common recycling methods, to be used in a number of different applications.
The longer fibers can be spun into quality yarns, with counts from to equal or be greater than the quality of fiber or yarn count than that of the virgin material with no loss of strength to the final product and increased hand and drape than what is seen from virgin materials. The yarn can be carded or combed, single ply or multi ply and counts can range from Single 4's to Single 60's or a multitude of Multi ply yarns.
These fibers preferably enter the cylinder machine with no less than 10 percent moisture content, and ideally have a moisture content up to around 30% moisture content. The materials are finished with approximately 8-15% moisture content in the final product, with the moisture being dependent on downstream manufacturing choices. The machines are held in a room with relatively high humidity, for example, greater than 50% relative humidity, and temperature typically between 70 and 80° F., to maintain quality materials throughout the operation.
The present invention will be better understood with reference to the following non-limiting examples.
The following process was used to create regenerated cotton fiber, and covers the process from raw material to finished roll goods produced from the fiber:
While the invention has been described in connection with the preferred embodiments and examples, it will be understood that modifications within the principles outlined above will be evident to those skilled in the art. Thus, the invention is not limited to the preferred embodiments and examples, but is intended to encompass such modifications.
