Patent Application
20180016735
The present invention relates generally to systems for and methods of treating cotton yarn with a cold aqueous alkaline solution. More specifically, the cold aqueous alkaline solution treatment improves the mechanical properties of the cotton yarn.
The textile industry is important in the U.S. and global economy. For example, the U.S. textile industry generated about $54 billion in export shipments in 2012. Cotton is the most important natural fiber in the textile industry with over 25 million tons of cotton produced from 35 million hectares from 50 countries in 2007. The textile industry is ever seeking to improve its quality control of the product.
To remain competitive in a global market, textile manufactures are always looking for new and unique ways to improve efficiency and lower costs. Historically, this has been achieved by the use of high-speed automated spinning machinery. In 1980, each spindle could transfer around 200 pounds of cotton per day. By 1995, that had increased to 600 pounds of cotton per day. Cotton thread strength increased from 26 grams/tex in 1990 to 29 grams/tex in 1995, which is about a 12% increase (Clapp et al., 2016).
Premium cotton fiber quality is necessary for high-tech spinning operations. For spinning speeds to increase, an increase in fiber strength is paramount. Methods to improve cotton fiber that spins into consistent, high-strength yarn at high speeds are sought by the industry. The limiting factor in improving cotton spinning quality control and production is cotton strength.
The use of alkaline solutions in a process called mercerization to improve cotton thread has been long recognized. Mercerization is treatment of cellulosic materials (e.g. cotton threads) with a caustic soda (NaOH) solution to improve their dying properties and thread strength and give them a lustrous appearance. Under the well-known mercerization process, cotton thread is held under specified tension for 10 minutes with an application of between 21%-23% NaOH at room temperature. During this process the chemical structure of the cotton fiber is altered whereby the fiber inter-converts from alpha- and beta-cellulose mixture to thermodynamically favorable cellulose II polymorph. The mercerization process causes the fiber cell walls to swell resulting in an increase in surface area and reflection and provides a softer feel. Optionally, an additional step of holding the thread over an open flame known as “singeing” or “gassing the thread” is often conducted.
Cotton fiber is composed of greater than 94% cellulose, 1-1.5% protein, and 1-1.5% pectin acid, mineral substances, acids, sugars, pigments and waxes (Textile Technologist, 2012). Cellulose is a particularly recalcitrant polysaccharide that is composed of hundreds to thousands of chains of β(1→4) linked D-glucose units held together by hydrogen bonding (Cai and Zhang, 2005; Heinze and Koschella, 2005; Li et. al., 2010; Liu et al., 2010; Medronho and Lindman, 2014; 2015; Nechita et al., 2010; Perez-Pimienta et al., 2013; Pinkert et al., 2009; Sarul et al., 2010; Satyanarayana et al., 2009; Sen et al., 2013; Tisserat et al., 2015; Zhao et al., 2008; Zhou et al., 2004). Much research interest has been devoted to break down cellulose into carbohydrate components to serve as intermediates for biobased fuels and products. Recently, cold alkaline aqueous solvent treatments (CAT) have been employed to break down the hydrogen bonds (Cai and Zhang, 2005; Cai et al., 2003; 2008; Chen et al., 2006; 2007; Fu et al., 2014; Gan et al., 2015; Keshk, 2015; Kihlman et al., 2012; 2013; Li et. al., 2010; Li et al., 2014; Liu et al., 2010; Liu et al., 2009; Lue et al., 2011; Mao et al, 2008; Qi et al., 2009; Qin et al., 2013; Ruan et al., 2004; Zhang et al., 2002; 2009; Zhao et al., 2008; Zhou et al., 2004). Cold sodium hydroxide (7% NaOH) and sodium hydroxide/urea solutions (˜7% NaOH/12% urea solution) at −12° C. are capable of breaking linkages between cellulose which could be subsequently regenerated to synthesize cellulose derivatives (Li et al., 2010; Zhou et al., 2002. It has been noted that cold alkaline treatments (e.g., 5% NaOH solution at −5° C.) of lignocellulosic fibers causes homogenous swelling but did not result in dissolvement (Li et al., 2010). Cai and Zhang (2005) employed various aqueous alkaline/urea solvents coupled with low temperature regimes to dissolve cellulose and found that LiOH H2O/urea was superior to NaOH/urea or KOH/urea. Associated with these studies was the observation that dissolved cellulose materials could regenerate into novel all-cellulose composites once the alkaline solution was removed (Cai and Zhang, 2005; Cai et al., 2004; Zhang et al., 2009; Li et al., 2014). Cotton linter could produce fibers via wet spinning following treatment with aqueous alkaline solutions with low temperatures (7% NaOH/12% urea at −10° C.) (Cai et al., 2004; Qi et al., 2009). In addition, regenerated fibers could be prepared via wet spinning from cellulose cotton linter using a 8% NaOH/6.5% Thiourea/8% urea solution at −8° C. (Zhang et al., 2009) or using a 9.5% NaOH/4.5% thiourea solution at −10° C. (Ruan et al., 2004). These cotton linter studies suggested that cellulose could be completely dissolved and reassembled to produce unique cotton threads.
What is needed is a method to produce unique cotton yarn that does not completely dissolve the cotton fibers and reassemble them into a cotton yarn, but rather starts with a cotton yarn and merely partially dissolves the cotton yarn to improve the mechanical properties.
The present inventive concept relates to systems and methods for the treatment of cotton yarn with a cold aqueous alkaline solution to improve the mechanical properties of the cotton yarn. In contrast to previous studies utilizing cold aqueous alkaline treatments, the present inventive concept is a plug-in technology step that can be added to existing commercial cotton yarn production procedures. Previous studies seek to assemble novel reconstituted threads from fully dissolved cotton fibers and linter. The present inventive concept relates to an intermediate step of only partial dissolution of the cotton yarn to improve its strength.
The present inventive concept has several unique characteristics. First, the thread composition remains the same, but the mechanical properties are improved. Second, the inventive process improves the mechanical properties of all cotton yarn and thread types. Third, in the manufacture of composite threads using commercial thread and cellulose gels the resulting composites are entirely biological in origin since they are not manufactured with plastic ingredients (i.e. nylon or polyester), therefore, they are composites that are completely biodegradable and compostable.
One object of the present inventive concept is to provide a method of treating cotton yarn. The method includes: providing a predetermined quantity of cotton yarn, partially dissolving the cotton yarn by applying a cold aqueous alkaline solvent, rinsing the partially dissolved cotton yarn with water and drying the cotton yarn. In some embodiments, the cotton yarn is pulled through a cold aqueous alkaline solvent that includes a predetermined quantity of dissolved cotton cellulose fiber in a gel state. In some embodiments, the cotton yarn is pulled through a first bath of cold aqueous alkaline solvent, a second bath of cold aqueous alkaline solvent gel with a predetermined quantity of dissolved cotton cellulose fiber, rinsed in a water bath and then dried.
Another object of the present inventive concept is to provide a system for treating cotton yarn. The system includes: a predetermined quantity of cotton yarn, a yarn-pulling apparatus, a bath of cold aqueous alkaline solvent through which the cotton yarn is pulled, and a water bath to rinse the cotton yarn. In some embodiments, the cotton yarn is pulled through a cold aqueous alkaline solvent that includes a predetermined quantity of dissolved cotton cellulose fiber in a gel state. In some embodiments, the cotton yarn is pulled through a first bath of cold aqueous alkaline solvent, a second bath of cold aqueous alkaline solvent gel with a predetermined quantity of dissolved cotton cellulose fiber, rinsed in a water bath and then dried.
The foregoing and other objects are intended to be illustrative of the invention and are not meant in a limiting sense. Many possible embodiments of the invention may be made and will be readily evident upon a study of the following specification and accompanying drawings comprising a part thereof. For example, dimensional values included herein are provided for exemplary purposes, and embodiments of the present invention contemplate systems and methods for treating cotton yarn having various dimensional values. Furthermore, various features and subcombinations of invention may be employed without reference to other features and subcombinations. Other objects and advantages of this invention will become apparent from the following description taken in connection with the accompanying drawings, wherein is set forth by way of illustration and example, an embodiment of this invention.
A preferred embodiment of the invention, illustrative of the best mode in which the applicant has contemplated applying the principles, is set forth in the following description and is shown in the drawings and is particularly and distinctly pointed out and set forth in the appended claims.
The following detailed description of the invention references the accompanying drawings that illustrate specific embodiments in which the invention can be practiced. The embodiments are intended to describe aspects of the invention in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments can be utilized and changes can be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense.
In this description, references to “one embodiment,” “an embodiment,” or “embodiments” mean that the feature or features being referred to are included in at least one embodiment of the technology. Separate references to “one embodiment,” “an embodiment,” or “embodiments” in this description do not necessarily refer to the same embodiment and are also not mutually exclusive unless so stated and/or except as will be readily apparent to those skilled in the art from the description. For example, a feature, structure, act, etc. described in one embodiment may also be included in other embodiments, but is not necessarily included. Thus, the present technology can include a variety of combinations and/or integrations of the embodiments described herein.
The present inventive concept is directed to systems and methods of treating cotton yarn. Referring to
Second, the cotton yarn is partially dissolved by applying a treatment of cold aqueous alkaline solvent. In some embodiments, the treatment is applied by pulling the cotton yarn through one or more bath of cold aqueous alkaline solvent 104. In some embodiments, the cold aqueous alkaline solvent 104 is a solution comprised of LiOH H2O, Urea, and water. In some other embodiments, the cold aqueous alkaline solvent 104 is a solution comprised of LiOH H2O, NaOH, Urea, and water. In the embodiments where the cold aqueous alkaline solvent 104 is a solution comprised of LiOH H2O, Urea, and water, preferably, the LiOH H2O is in the range of 5% to 15% of the total solution, and more preferably 8.1%. Preferably, the urea is in the range of 10% to 20% and more preferably 15%.
In the embodiments where the cold aqueous alkaline solvent 104 is a solution comprised of LiOH H2O, NaOH, Urea, and water, preferably, the LiOH H2O is in the range of 3% to 6% of the total solution, and more preferably 4.8%. Preferably, the NaOH is in the range of 3% to 6% and more preferably 4.4%. Preferably, the urea is in the range of 10% to 20% and more preferably 15%.
In some embodiments, the cold aqueous alkaline solvent 104 is maintained at a temperature in the range of −15° C. to −5° C., preferably −12.5° C. In some embodiments, the cold aqueous alkaline solvent includes some dissolved cotton cellulose fiber in a gel state 105. In some embodiments, the cotton yarn receives two treatments, a first one of cold aqueous alkaline solvent 104 and a second of cold aqueous alkaline solvent gel (that includes some dissolved cotton cellulose fiber) 105, before being rinsed and dried. In such embodiments, preferably the first treatment 104 lacks dissolved cotton cellulose fiber in a gel state and the second treatment 105 includes dissolved cotton cellulose fiber in a gel state. In some preferred embodiments, the dissolved cotton cellulose fiber is in the range of 1% to 3%, and more preferably 2.2%.
Third, after the cotton yarn is partially dissolved in the cold aqueous alkaline solvent 104, it is rinsed in a water treatment 106. Fourth, it is dried.
In some embodiments, the cotton yarn is pulled (103 indicates the direction of pull) through one or more cold aqueous alkaline solvent bath 104 at a rate that is in the range of 42 to 286 inches per minute, preferably 118. In some embodiments, the cotton yarn is pulled through a water bath 106 at the same rate as the solvent 104. In some embodiments, the cotton yarn remains soaking in at least one of the solvent baths for a period of time in the range of 5 seconds to 5 minutes, preferably 5 to 10 seconds. In some embodiments, the cotton yarn is rinsed in the water bath 106 for a period of time in the range of about 1 to 5 minutes.
In other embodiments of the present inventive concept, a system for treating cotton yarn is provided. The system includes the methods as described above.
Unique and strong cotton yarn were obtained by subjecting cotton yarn to cold alkaline aqueous solvents and cold temperature treatments with and without additional cotton reinforcement. Subjection of commercial threads, used to manufacture textile, to a dilute matrix of a cellulose material or gel (e.g., cotton) that was liquefied using an aqueous alkaline solvent solution (NaOH-urea, LiOH-urea and/or a LiOH/NaOH-urea mixture) under cold temperatures (−5° C. to −15° C.) caused the matrix cellulose to readily adhered and/or incorporate/encapsulate the cellulose into the thread. Physical testing of these cold alkaline treated threads showed that treated threads had superior mechanical properties compared to untreated threads. High speed runs of cotton threads using a motorized pull-thru system demonstrated that large scale treatment of cotton thread with cold aqueous alkaline solvent is feasible.
In the examples that follow, the following materials were used: Commercial cotton thread 30/1 OE cones were provided by Cotton Inc., Cary, N.C., USA. The cotton thread linear density was 20 tex. Commercially available alkaline hydroxides (LiOH.H2O and NaOH) and urea were of analytical grade (Aldrich-Sigma, St. Louis, Mo.) and used as received without further purification. Rolled cotton (Dukal Corporation, Hauppauge, N.Y.) provided cotton fibers and were used without modification.
Solvent formulations employed in these examples were comprised of LiOH H2O:Urea:water aqueous solution (weight ratios of 8.1:15:76.9) and LiOH H2O:NaOH:Urea water (weight ratios of 4.8:4.4:15:75.8). Initially, cotton threads were given various solvent treatments pre-cooled to −12.5° C. for various durations (1 to 5 min) followed by soaking in a water bath for 5 min to determine their effect on cotton thread. Following solvent testing threads were soaked in water for 5 min and dried with a heat gun (model 1875 Watt ionic dryer, Revlon, New York, N.Y., USA). Unless indicated elsewhere the following procedure was employed to modification of cotton yarn. The assembly of the apparatus for mass treatment of thread using a pulling thread through solvents was constructed as shown in
The mechanical properties of cotton threads were tested for tenacity at break (TB), tensile modulus (E), tensile strength (σu), and elongation at break (% El)) using a universal testing machine (Instron Model 1122, Instron Corporation, Norwood, Mass.). Cotton threads were evaluated using ASTM D2256-80 method. The gauge length was 101.6 mm and the tensile speed was 12.5 mm per min. Thirty to fifty specimens of each formulation were tested. The average values and standard errors were reported. Comparisons of the mechanical properties of the treated threads with commercial non-treated thread were conducted through a normalization processes. The untreated and treated thread were examined using a Wild Heerbrugg M5 Stereo dissecting microscope (Leica Microsystems GMbH, Wetzlar, Germany) to evaluate the effect of the cold aqueous alkaline treatments on their morphologies.
As shown in Table 1 (below), solvent soaking of cotton yarn altered of the mechanical properties. For example, soaking the cotton yarn for 5 min in a solvent solution changed the αu, E, % EL, and TB values compared to untreated thread by +24%, −7%, −17%, and +28%. The strength properties of the thread were improved while the stiffness and elongation properties declined (Table 1). Tensile strength and Tenacity at Break properties are considered the more important mechanical properties associated with cotton thread in order to obtain an improved thread that would result in improved textiles. Therefore, it is apparent that a simple cold aqueous alkaline treatment did improve cotton thread. In further studies, soaking thread in solvent/gel solution only for 1 to 5 min also had effects on the mechanical properties (Table 1). For example, soaking thread for 5 min in a solvent solution changed the σu, E, % EL, and TB values compared to untreated thread by +39%, +9%, −20%, and +28%. Likeness, in tests were thread was soaked in solvent 1 min followed by a solvent/gel treatment of 1, 3 or 5 min resulted in similar tensile strength improvements (Table 1). Optical examination of the thread treated with solvent/gel compared to the untreated thread clearly revealed a morphological change in the thread. The untreated thread exhibited the characteristic weave pattern and stray fibers while the treated thread did not. This indicates the cold alkaline treatment causes a fusion of the thread.
Tests were conducted using the cotton thread pull-thru system shown in
1. A system for treating cotton yarn for improved mechanical properties, the system comprising:
While the present general inventive concept has been shown in the drawings and fully described above with particularity and detail in connection with what is presently deemed to be the most practical and preferred embodiment(s) of the invention, it will be apparent to those of ordinary skill in the art that many modifications thereof may be made without departing from the principles and concepts set forth herein, including, but not limited to, variations in size, materials, shape, form, function and manner of operation, assembly and use.
It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall there between. Hence, the proper scope of the present general inventive concept should be determined only by the broadest interpretation of the appended claims so as to encompass all such modifications as well as all relationships equivalent to those illustrated in the drawings and described in the specification.
Finally, it will be appreciated that the purpose of the annexed Abstract is to enable the U.S. Patent and Trademark Office and the public generally, and especially the scientists, engineers and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. Accordingly, the Abstract is neither intended to define the invention or the application, which only is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.
The following references are cited throughout this disclosure and are incorporated by reference. Applicant makes no statement, inferred or direct, regarding the status of these references as prior art. Applicant reserves the right to challenge the veracity of statements made in these references.
This application claims priority pursuant to 35 U.S.C. 120 to co-pending U.S. patent application Ser. No. 15/341,972, entitled “LIGNOCELLULOSIC AND GEOPOLYMER COMPOSITE SYNERGIES AND POLYMER-BASED ADDITIVES FOR GEOPOLYMER COMPOSITE,” filed Nov. 2, 2016, which claims priority to U.S. Provisional Patent Application Ser. No. 62/249,765, entitled “LIGNOCELLULOSIC AND GEOPOLYMER COMPOSITE SYNERGIES AND POLYMER-BASED ADDITIVES FOR GEOPOLYMER COMPOSITE,” filed Nov. 2, 2015, the entire disclosures of which are incorporated herein by reference. This application also claims priority pursuant to 35 U.S.C. 120 to co-pending U.S. patent application Ser. No. 15/429,058, entitled “LIGNOCELLULOSIC COMPOSITES PREPARED WITH AQUEOUS ALKALINE AND UREA SOLUTIONS IN COLD TEMPERATURES SYSTEMS AND METHODS,” filed Feb. 9, 2017, which claims priority to U.S. Provisional Patent Application Ser. No. 62/293,172, entitled “LIGNOCELLULOSIC COMPOSITES PREPARED WITH AQUEOUS ALKALINE AND UREA SOLUTIONS IN COLD TEMPERATURES SYSTEMS AND METHODS,” filed Feb. 9, 2016, the entire disclosures of which are incorporated herein by reference. This application also claims priority pursuant to 35 U.S.C. 119(e) to co-pending U.S. Provisional Patent Application Ser. No. 62/377,316, entitled “COLD AQUEOUS ALKALINE TREATMENTS FOR COTTON YARN AND RELATED SYSTEMS AND METHODS,” filed Aug. 19, 2016, the entire disclosure of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62377316 | Aug 2016 | US | |
| 62293172 | Feb 2016 | US | |
| 62249765 | Nov 2015 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15429058 | Feb 2017 | US |
| Child | 15682146 | US | |
| Parent | 15341972 | Nov 2016 | US |
| Child | 15429058 | US |
