Method for the surface application of chemical compounds to both synthetic and natural fibers and a system for same

Abstract

The present invention relates to a surface treatment and a method for its application for the introduction of a wide variety of differentiating properties to fibersin sliver form through a surface treatment of said fibers. The system can accommodate chemical processes, sonochemical processes, and acoustic cavitation processes whereby the fibers are speckled or plated with at least one predetermined compound in a liquid medium to impart at least one desired property to the fibers and for the orderly inclusion of such treated fibers in sliver form having such properties in yarns, woven, knit, or non-woven textiles.

Claims

1. A surface treatment process for treating a plurality of cellulose fibers, comprising the steps of: providing at least one predetermined inorganic particulate material in a liquid medium, said inorganic material remaining at least partly in particulate form in the medium; placing sliver comprising cellulose staple fibers on a transporting means; incrementally introducing the sliver into a trough within a surface treatment apparatus so that there is controlled dispersion of the sliver fibers transported within the liquid medium contained in the trough, the sliver transported on a moving double web with the fibers sandwiched therebetween thereby minimizing fiber dispersal and disorder in the liquid medium; activating at least one transponder in acoustic communication with at least one sonotrode for generating sound pressure waves in the liquid medium which embed the inorganic particulates into the individual sliver fibers; and, reconstituting the fibers back to sliver.

2. A surface treatment process according to claim 1, wherein the at least one sonotrode emits sound pressure waves at a frequency of about 15 to about 30 KHz.

3. A surface treatment process according to claim 1, further comprising a step of adding a surfactant to the liquid medium in order to improve fiber separation during the surface treatment process and in order to assist in the reconstitution of the fibers to sliver form.

4. A surface treatment process according to claim 1 further comprising a step of winding the fibers after surface treatment, thereby facilitating reconstitution of the fibers to sliver form.

5. A surface treatment according to claim 1, wherein said at least one predetermined inorganic particulate material is a flame retarding compound containing waters of hydration for imparting non-ignition or retarded ignition properties to said fibers.

6. A surface treatment according to claim 5, wherein said flame retarding compound is a hydrated compound selected from a group consisting of, magnesium hydroxide, alumina trihydrate, and combinations thereof.

7. A surface treatment according to claim 1, wherein said at least one predetermined inorganic particulate material is an antimicrobial compound containing metals and/or oxides thereof for imparting antibacterial, antifungal, and/or antiviral properties to said fibers.

8. A surface treatment according to claim 1, wherein said at least one predetermined inorganic particulate material is selected from a group consisting of copper oxide, silver, silver oxides, zinc, zinc oxide, and combinations thereof for imparting pesticidal properties to said fibers.

9. A surface treatment according to claim 7, wherein said at least one inorganic particulate material is selected from a group consisting of copper, copper oxides, silver, silver oxides, and combinations thereof.

10. A surface treatment process for treating a plurality of cellulose fibers, comprising the steps of: providing at least one predetermined inorganic particulate material in a liquid medium, said inorganic material remaining at least partly in particulate form in the liquid medium; placing sliver comprising cellulose staple fibers on a transporting means; incrementally introducing the sliver into a plurality of troughs within a surface treatment apparatus so that there is control of the sliver transported on a plurality of movable conveyors within the liquid medium contained in the plurality of troughs, each of the troughs is configured as an elongated canal positioned to be spaced apart and substantially parallel to, and operated in parallel with, the other canals, each canal is sized to accommodate one of the plurality of moving conveyors passing through the canal and to limit dispersion of the fibers therein; supplying a plurality of weighted elements to constrain the fibers of the sliver so as to remain at least partially submerged in the liquid medium and to retain their parallel orientation as they are transported through the liquid medium in the canals; activating at least one transponder in acoustic communication with at least one sonotrode for generating sound pressure waves in the liquid medium which embed the inorganic particulate material into the individual sliver fibers; and, reconstituting the fibers back to sliver.

11. A surface treatment process according to claim 10, wherein the at least one sonotrode emits sound pressure waves at a frequency of about 15 to about 30 KHz.

12. A surface treatment process according to claim 10, further comprising a step of adding a surfactant to the liquid medium in order to improve fiber separation during the surface treatment process and in order to assist in the reconstitution of the fibers to sliver form.

13. A surface treatment process according to claim 10, wherein said at least one predetermined inorganic particulate material is an antimicrobial compound containing metals and/or oxides thereof for imparting antibacterial, antifungal, and/or antiviral properties to said fibers.

14. A surface treatment process according to claim 10 wherein the plurality of weighted elements is a plurality of weighting wheels.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic representation of a production line for carrying out the process of the present invention.

(2) FIG. 2 is a partial exploded view of the canal table shown in FIG. 1.

(3) FIG. 3 is a side cut view of the table in FIG. 1 showing the position of the sonotrode in relation to the sliver and water

(4) FIG. 4 is a side cut view of the table from FIG. 1 showing the position of the weight wheels

(5) FIG. 5 is an SEM picture showing cavitated fibers spun into a yarn. Shown here are cavitated fibers with alumina trihydrate through an acoustic cavitation process.

(6) FIG. 6 is an SEM picture showing acoustically cavitated fibers applying alumina trihydrate which were spun into a yarn after 50 washings. The fibers did not ignite indicating a product lasting for the life of the product.

(7) FIG. 7 is an SEM picture showing a single fiber after exposing it to acoustic cavitation.

(8) FIG. 8 is an SEM picture showing a cross section of a single fiber after exposing it to acoustic cavitation. Note that the white dots are the chemical compound which can be seen to have penetrated the surface of the fibers deeply.

(9) FIG. 9 is an SEM picture showing a chemically coated fiber using an oxidation/reduction process. Note the 100% coverage of the fiber.

(10) FIG. 10a is a 20 micron section of cavitated Ag4O4 (large particles) on a sonochemical nano deposition of a CuO on a copper plated cotton fiber

(11) FIG. 10b is a 4 micron section of cavitated Ag4O4 (large particles) on a sonochemical nano deposition of a CuO on a copper plated cotton fiber

(12) FIG. 10c is a 1 micron section of cavitated Ag4O4 (large particles) on a sonochemical nano deposition of a CuO on a copper plated cotton fiber

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

(13) Referring now to FIG. 1, fibers are prepared in the form of sliver (2), which slivers are, for example stored, as being wound in a barrel (4) as is common for the yarn production industry. The skilled artisan will appreciate that the source for the slivers and/or the maintenance of the same may be via any means and obtained from any source. The sliver is fed into the apparatus, for example, by leading the sliver through a track (6). The track may be supported at certain intervals, for example, by the presence of supporting metal rollers (8) that provide for the movement of the sliver (2) along the designated course, for example, as depicted herein, including passage over a fitted table (10). The apparatus and various support structures allow for incremental feeding of the sliver along the designated path, without breakage. Referring now to FIG. 2, which provides an exploded view of table (10) in FIG. 1, it can be seen that the table will be fitted with a series of indentations or recessed cells (14), which indentations/recessed cells are sized and of a material to allow for the housing of the aqueous solution therein. The sliver is guided along the length of the table (10), which table may incorporate an apically located film layer (16). Such film may, according to this aspect, be relatively hydrophobic in nature, for example, by being comprised of polypropylene or polyethylene. The film may in turn be fed along the surface of the table, much as the sliver is fed along the table, as a conduit providing smooth passage of the sliver. The film, in turn may be stored as a roll/reel, (18) which is in turn fed into a take-up reel (20) at the other side of the table (10). The sliver is then introduced on top of the film layer, as both are advanced along the length of the table. While it is not shown in this illustration it is possible to use a double flexible web such as a screen to catch the sliver and hold it in place as well. However, the system as described herein is simpler to construct.

(14) As the film carrying sliver is advanced, it comes into contact with the recesses/indentations in the table, and thereby becomes exposed to the aqueous solution contained therein (22). Since the sliver may have a tendency to float, which will interrupt the cavitation process, it may be necessary to weigh down the moving sliver. This may be achieved with the aid of some weight wheels (26) as depicted in FIG. 4 which fit in the canals (14) of the table (10). Upon exposure to the aqueous environment, the sliver comprising the fibers becomes fully wet and the fibers are then less tightly associated as compared to their orientation when dry. The sliver moves along the 1 meter table in around 15 seconds which is sufficient to affect the full cavitation desired. Spaces form between the fibers which spaces fill with water and which spaces act as the vehicle for fiber treatment because the fibers at this point are separated. The orientation will be maintained as long as the water remains undisturbed and the weight wheels (26) are parallel to the water canals (14). At this point, the fibers are completely separated. The timing of exposure of the sliver to the aqueous environment may be carefully controlled, ensuring that the fibers maintain ideal orientation in order to reform into a sliver with parallel-arranged fibers at the conclusion of the process. The timing of the immersion may also be a function of the speed of the carrier.

(15) As the dry fibers move with the film (16) in the canals (14), water and chemicals (22) from chemical feed tank (32), are sprayed on the fibers to fill the canal or trough and cover the fibers (13) with liquid. The aqueous solution is sprayed at a very high pressure which submerges the fibers while also wetting them completely. The fibers will have a tendency to float so it is preferable to weigh them down with wheels (26) to at least partially immerse them in the liquid medium so as to assist in maintaining exposure of the fibers in the liquid medium and maintaining an ordered orientation of the fibers, or if more water is needed by adding extra spray nozzles. The process preferably occurs at a relatively high speed in order to prevent the natural tendency of the fibers to disperse and lose their orientation.

(16) The fibers, in some embodiments, pass under a part of a sonotrode (24). In an embodiment it is possible to replace the sonotrode with a chemical dispenser so that the same machinery can be used for a chemical reduction processes.

(17) According to this aspect, and in some embodiments, the processes of this invention may make further use of the periodic arrangement of weighting structures, such as weighting wheels 26, positioned over or at least partially over, or proximal to the positioning of the recesses/indentations in the table, which in turn may facilitate better fiber submersion.

(18) According to this aspect, and in one embodiment of an apparatus which facilitates execution of the methods/processes of this invention, provides for passage of the fibers, as the fibers (13) leave the table (10) to pass through squeeze rolls (28) removing most of the water from the fibers (13) and compacting of the fibers back into sliver (12) form. It will be appreciated, however, that other arrangements may be utilized, whereby the film/sliver may be advanced along a surface, brought into periodic contact with the described aqueous solutions containing the component as described, which facilitates exposure of individual fibers in the sliver, whereby a preponderance of such fibers associate with the component, and ultimate reassembly of the sliver is accomplished, and such arrangements may not necessarily make use of automated parts, may be suitable for small scale applications, or alternatively may be modified to suit industrial applications, and all such arrangements are to be considered as contemplated and a part of this invention.

(19) Furthermore, in some embodiments of the arrangement as described hereinabove, the water will flow down the rewinding film (16) into the collection tank (30) which water and chemicals (22) can then be recycled back to the water and chemicals feed tank (32) providing a cost-saving feature to the methods/processes as herein described.

(20) In some embodiments, after the sliver (12) leaves the first set of squeeze rolls (28) the sliver is picked up by a second set of squeeze rolls (34) or any appropriate number of additional squeeze rolls, as a means of removing excess aqueous solution remaining in association with the film/sliver. After the first squeeze around 97% of the water is removed. The sliver is now in the form of a flat ribbon with parallel fibers. In this form the sliver can be moved to the next section for drying since the ribbon will have a small amount of integrity. This formation will now allow the sliver to move away from the supporting film and on to the belt that will enter the oven for drying. The sliver then travels on to the second table (36). The base (38) of this table (36) is a metal mesh so that the sliver sits on the mesh and travels with it allowing hot air to pass through the mesh and the moist sliver. The sliver enters the drying oven (40). As the sliver exits the drying oven the sliver then goes into a set of tracks that facilitates the sliver for winding (42) and entry into the collection sliver barrel (44).

(21) Referring now to FIG. 3 there are seen side views of two different sonotrodes within the canals (14) provided in table (10) in the apparatus of FIG. 1. As stated the fibers (13) in sliver form travel on a moving film or trapped in a moving web to catch the fibers so that they do not disperse unnecessarily due to exposure to the water (16) which is pressed into the canals (14). Two different sonotrode configurations, a single headed sonotrode (46) and a double headed sonotrode (48) and how they fit into the canal (14) are shown. The film (16), that travels, can be seen across the cut of the canal table (10)as well as the position of the fibers (13) in relationship to the film (16) the sonotrodes (46) and (48) and the water level (50) The waves that travel through the water will cause the fibers to loosen and open thus allowing full coverage by the chemicals in the water. There is only one sliver per trough.

EXAMPLES

Example 1

Fire Retardant Chemistry Containing Waters of Hydration

(22) A sliver was prepared so that it had a slight twist (around 4 twists per meter) and weighed 3 to 8 grams per meter. The sliver can be made from any staple fiber such as but not limited to cotton, rayon, polyester, and nylon. The sliver was run through the system described but previous to the sliver being placed in the canals of the belt a small amount of Fire Retardant (FR) chemical compound in the form of a fine powder, usually no more than 5 microns in size, was placed in the water that was sprayed on the fibers. We note that the FR can also be put on the dry belt. The powder mixed into the aqueous carrier when the radio waves are turned on. The powder can be any hydrated insoluble compound, such as, but not limited to, sodium borate decahydrate or alumina trihydrate, In this case, we used a combination of alumina trihydrate and magnesium oxide and in a second example sodium borate decahydrate. The amount of chemical may be varied, depending upon the application, and as a consequence of the desired application density, cost, etc. Furthermore, it is possible to recycle the applied chemical by routing the excess chemicals to a collection tank. No more than 1 gram of powder per meter is required for the process, however more can be added to the water without reduction in the efficiency of the process. The fibers travel along the conveyor belt for as little as 15 seconds over a distance of 1 meter while being exposed to the acoustic irradiation during the entire duration of the time the fibers were in the water. It has been found that in as little as 1 second per meter, a 5 gram amount of cotton fiber was covered with no less than 30% surface modification. A bubbling around the fibers was observed indicating that cavitation took place. The fibers in the sliver immediately began to drift apart within the canal and separated. The fibers were found to remain orderly while in the canal when weight wheels (26) were placed every 25 to 50 centimeters and the fibers remained submerged. The sonotrodes were activated just before the sliver and water and hydrated compound were added to the conveyor belt. The sonotrodes remained on as long as the fibers, water, and chemicals were in the canal and continued their work for the length of the conveyor belt which was adjusted to assure an even coating over 100% of the fibers or as needed. After the coating was complete, the loose fibers were then quickly squeezed to remove almost all the water (the sliver was moist but condensed) and the sliver once again solidified and was moved to the drying station.

(23) Non exemplified embodiments of such fibers can be prepared containing non-ignition or fire retardant properties imparted to the cellulose or polymer fiber substrate, which were then blended into a yarn using conventional techniques. This yarn was then woven into a fabric yielding a fire retardant fabric.

(24) FIGS. 5, 6, 7, and 8 are SEM photographs demonstrating treated fibers both individually and included in a yarn and show the resistance to abrasion and washing after 50 washings by a process as described in Example 2 below.

(25) FIG. 5 shows a fiber immediately after cavitation while FIG. 6 shows the same fiber after extensive (50) high temperature washings (60 Centigrade). In sample 5 there was no ignition of the fiber when treated with both alumina trihydrate and magnesium hydroxide. The same non-ignition occurred in the yarn of FIG. 6 indicating a life of the fabric efficacy.

(26) FIGS. 7 and 8 are the fibers in FIG. 6 (after washing) at higher magnifications. Note the depth of the compound which permeated the surface of the fiber in FIG. 8 as can be seen in the cross section photograph.

Example 2

Preparation of a Sliver Incorporating Individual Fibers Associated with Metals and Metal Oxides

(27) A sliver is prepared so that it has a slight twist (around 4 twists per meter) and weighs 3 to 8 grams per meter. The sliver can be made from any staple fiber such as but not limited to cotton, rayon, polyester, or nylon. The sliver is run through the system described but just previous to the sliver being placed in the canals of the belt a very small amount of a predetermined chemical compound in the form of a fine powder, usually no more than 5 microns in size, is placed in the water and chemical delivery tank (32) or on the dry belt. The powder should be zinc or any form of zinc such as zinc oxide but in preferred embodiments should be zinc oxide with no less than a 97% purity level. Other metals and metal oxides can be used such as copper and/or its oxides or silver and/or its oxides by way of example. The amount of the predetermined chemical compound is not critical because the fiber will pick up what is given off by the irradiation and what is left in the canal will be collected after the wet process is complete. No more than 1 gram per meter of powder is required. The sliver travels along the conveyor belt for as little as 15 seconds but no more than 1 minute and is exposed to the irradiation during this period of time while it is in the liquid medium. A bubbling around the fibers will be observed which indicates the cavitation is taking place. The fibers in the sliver will immediately begin to drift within the canal and separate. It is this separation that will allow for complete coverage of the fibers with the predetermined chemical compound for deposition. It is important to make sure that the fibers remain orderly while in the canal and so rollers are preferably placed no less than every 30 to 50 centimeters to assure that the fibers remain submerged. The sonotrodes are activated just before the sliver and water and predetermined chemical compound are added to the conveyor belt. The sonotrodes will continue their work along the length of the conveyor belt which is adjusted to assure an even coating over 100% of the fibers. After the coating is complete the loose fibers are then quickly squeezed to remove almost all the water but more importantly to solidify the fibers into sliver once again so that it will have its own integrity which will allow it to be moved to the drying station.

(28) The deposition of metal oxides rendered the treated fibers with both antimicrobial and UV inhibiting qualities. Antibacterial fabrics are widely used for production of outdoor clothes, under-wear, bed-linen, and bandages. UV inhibiting and antimicrobial resistance is very important in textile materials, having effects amongst others on comfort for the wearer. The deposition of metal oxides known to possess antimicrobial activity, namely TiO2, ZnO, MgO, CuO, Ag, and Ago, can significantly extend the end uses of textile fabrics and prolong the period of their use.

(29) Copper oxide is widely cited in the literature for its antibacterial, antifungal, and antiviral qualities. It is also cited as an anti-mite fabric (The FASEB Journal, article 10.1096/fj.04-2029 Published online Sep. 9, 2004). Zinc has also been recognized as a mild antimicrobial agent, non-toxic wound healing agent, and sunscreen agent because it reflects both UVA and UVB rays (Godrey H. R. Alternative Therapy Health Medicine, 7 (2001) 49).

(30) Antibacterial, wound healing, dust mite inhibition, medical compound delivery, and UV inhibition qualities can also be imparted to cellulose or polymeric fibers using an acoustic cavitated or sonochemical coating with the application of metal oxides.

(31) The deposition of metal oxides is known for their various activities and in the present invention TiO2, ZnO, MgO, CuO, Ag, and AgO can be applied using the system described.

(32) The use of metals and metal oxides is well documented for a variety of end uses and is described throughout the literature. However, the products that are produced using the normal treatment of a textile substrate limits greatly the applications of these metals to the various industries and healthcare applications.

(33) The SEM photographs demonstrated herein show the adherence of copper oxide particles to the outside of the fiber which were cavitated to facilitate attachment of the copper oxide to the fibrous substrate as per the description above.

(34) Described in the literature are treatments as follows:

(35) Systems that use an oxidation reduction from a soluble metal on to a fiber or textile such as described in U.S. Pat. No. 5,981,006 Gabbay Application of a Metallized Textile.

(36) Systems that include a metal oxide in a polymer by introduction of the compound through a carrier into a pre-extruded polymeric slurry such as described in US Patent Application 20080193496 Antimicrobial and Antiviral Polymeric Master Batch, Processes For Producing Polymeric Materials Therefrom and Products Produced Therefrom

(37) Systems that use sonochemical irradiation to woven or non-woven textile substrates such as described in IL 2009/00645 Gedanken et al. Sonochemical Coating of Textiles with Metal Oxide Nanoparticles for Antimicrobial Fabrics

(38) In treating at the fiber level the present invention provides for a greater control of dosage of the antimicrobial compounds or UV inhibition compounds. It was found that 30% of the fibers treated with a copper oxide in a fabric were sufficient to produce a homogenous pad that was effective as a wound healing device but in some cases less was sufficient. At the same time, other elements can be added to the pad, should they be desired, by simply adding different treated fibers. In theory, one could add a fire retardant (FR) quality to a fabric that is treated to destroy microbes which would find use in hospitals and public institutions.

Example 3 (Diatomaceous Earth and Organic Insoluble Compounds)

(39) A sliver is prepared so that it has a slight twist (around 4 twists per meter) and weighs about 2 to about 20 grams per meter, and preferably about 3 to about 8 grams per meter. The sliver can be made from any staple fiber such as but not limited to cotton, rayon, polyester, and nylon. The sliver is run through the system described but just previous to the sliver being placed in the canals of the belt a very small amount of the predetermined chemical compound in the form of a fine powder, usually no more than 5 microns in size, is placed in the water and chemical delivery tank (32) or on the dry belt. The powder can be food grade diatomaceous earth with a purity level of no less than a 97%. Diatomaceous earth has been chosen for this example because it is approved by the EPA as a pesticide for use against the common bed bug, Cimexlectularius as well as other exo-skeletal pests such as fleas, ticks, beetles, roaches and mites.

(40) As it applies to exo-skeletal bugs in general and bed bugs in particular, the normal application of diatomaceous earth is in loose powder form which is deposited as a powder between the folds of textiles in a mattress or on the floor so that the bed bugs will walk across the powder in order to reach its human target. Diatomaceous earth is fossilized/silicated diatoms. The powder has sharp edges which scrapes the exo-skeleton and causes dehydration of the bug. When the diatomaceous earth is cavitated into a fiber the same kill mechanism will be available to destroy the bug with the advantage that the user of the powder is not exposed to the loose powder about which there is a problem of exposure.

(41) Furthermore, an organic compound that is encapsulated and is capable of withstanding the oscillation of the acoustic cavitation process can be used in the same manner as described for the application of diatomaceous earth or any of the compounds discussed herein. Powder size of the encapsulated compound can be as large as 15 microns which has been shown to still be within the acceptable parameters of the process as described above. Encapsulated compounds which protect soluble compounds is well known to those familiar with the art and are commonly used in protecting organic compounds from denaturing when in creams or aqueous solutions. Because the process is conducted at room temperature, the encapsulating material can be compounds such as but not limited to silicones, waxes, and cellulose based compounds which will not be affected by the heat of the process. A mechanism for removal of the encapsulate can be pressure, heat, or time which will then release the active ingredient embedded in the textile to the desired end use.

(42) Examples of such encapsulated organic compounds include aroma oils to impart pleasant odors or to mask negative odors, nano-compounds or compounds such as nicotine for transdermal patches, antibiotics for bandages, or growth factors and other peptides as compound delivery systems. These compounds possess medicinal or cosmetic qualities that can be delivered by a patch, garment, or textile strip.

Example 4

(43) Slivers comprised of 100% cotton were maintained at room temperature and applied to an apparatus similar to that illustrated in FIG. 1. Ultrasonic cavitation was accomplished via a 1000 watt sonotrode, set at 24 Kh with a 15 seconds exposure, in total, while the sliver was immersed in a recess containing tap water. Silver nitrate crystals (97% pure) were added to the water and put into solution. This solution was now sprayed with the water in the canal. Ammonia was added to the water and the sonotrode was activated. As the reductant converted the silver nitrate to silver the acoustic waves immediately caused the chemical reduction process and then, immediately with the creation of the silver cavitation, which kept the silver particles from agglomerating, immediately attached them to the surface of the fibers as per (FIG. 10). In comparison, in FIG. 9 a reduction process is demonstrated using only a chemical reaction as per electroless plating. While the coating evenly covered the entire fiber it did not have a resistance to abrasion or washing and was easily removed from the surface of the fiber.

(44) The same process was done with the alumina trihydrate but without a reduction process. The raw chemistry was added to the water before cavitation and the size of the particles that were placed in the water was the same as the particles after attachment to the fiber. The sonotrode was then activated and as can be seen in FIG. 5 the particles attached themselves to the fibers.

(45) It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative examples and attached figures and that the present invention may be embodied in other specific forms without departing from the essential attributes thereof, and it is therefore desired that the present embodiments and figures be considered in all respects as illustrative and not restrictive, reference being made to the appended claims, rather than to the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.