Electrostatic Application of Yarn Spin Finishes for Carpet Manufacturing

Project Title:  Electrostatic Application of Yarn Spin Finishes for Carpet Manufacturing

Continuation Project? Yes  (No. of Prior Years Funded 2  )

Research Team Leader  Dr. S. Edward Law / Prof. Warren S. Perkins

Phone (706)542/0866 & 4885

Team Leader's E-mail  edlaw@engr.uga.edu / wperkins@fcs.uga.edu

Team Leader's Institution University of Georgia

Industry Partner Contact  Dr. Timothy P. Blatchford Phone  (423)875-7655

Industry Partner's Company  DuPont - Fiber Surface Research Laboratory 

Industry Partner's Location Chattanooga, TN 

Proposed Research Team:

Researcher Name and Institution  Phone

Dr. S. Edward Law - U.Ga. (706) 542-0866

Prof. Warren S. Perkins - U.Ga. (706) 542-4885

Requested Funds:

College or University $$ Requested

University of Georgia $ 100,780 

Total TIP-PFFP Funds Requested for FY 2003 $ 100,780 

 (excluding equipment)

(Confidential - Patentable material not for public disclosure) EXECUTIVE SUMMARY

This project continuation impacts industry by directly addressing the following research need which has been identified by the TIP-PFFP carpet-sector as an industry-wide priority:

. Environment and Health - Develop new technologies and/or evaluate commercially available technologies that reduce industry's impact on the environment and the health of its workers - specifically by reduction of yarn spin finishes and their associated air- and water-pollution problems.

Minimization of process-enhancing surface finishes applied to carpet fiber is attractive for both environmental and economic reasons. Spin finish applied by the fiber producer, along with processing lubricants added by the carpet manufacturer, contribute 60-80% of the pollution load (COD) in wastewater from carpet manufacturing. Volatilization of spin finishes during heat-setting of carpet yarn generates appreciable emission of VOC air pollutants of concern in both the ambient and the workplace atmospheres. At a typical add-on level of 0.5-1.5% weight basis, the finish costs fiber and carpet manufacturers many millions of dollars annually.

Due primarily to lack of uniformity of the fiber coating achieved by conventional application methods, excess finish is routinely dispensed to ensure satisfactory performance. Furthermore, it is topically applied to the peripheral surface of the coalesced bundle and not more effectively onto the individual filaments issuing from the spinnerettes. Increased uniformity of coverage, and especially onto individual filaments, thus offers significant overall reduction in the weight percent of finish while likely improving fiber-processing characteristics. This TIP-PFFP project thus addresses water quality issues by source reduction instead of more costly wastewater treatment.

Numerous other industries and commercial sectors routinely achieve highly efficient and uniform mass-transfer of liquid- and powder-coating particulates onto a diverse range of deposition surfaces and substrates ¾ nearly all relying upon electrostatic force fields for their effectiveness. Well known charged-particulate processes include: ink-jet printing; toner deposition in xerographic copying; electrostatic "painting" of liquid sprays and powder finishes onto major items of manufacture, e.g., most automobiles, appliances, etc.; electrostatic spraying of chemical and biological pesticides onto crops; electrostatic precipitation of air pollutants from smoke stacks; and the electrostatically aligned deposition of fibers and abrasive particles, respectively, in the manufacture of flocked fabric items and sandpapers. Cumulative product value reliably coated via electrostatic means exceeds $100 billion annually.

This continuing TIP-PFFP project will further develop and incorporate an electrostatic-coating process to uniformly and efficiently deposit yarn spin finishes for carpet manufacturing. Results thus far uncovered little prior published electrostatic individual-fiber coating work on which to build. Year #2 therefore refined the theoretical concepts and mathematical models specifically applicable to charged finish deposition onto high-speed insulating filaments and identified likely technical challenges to overcome in engineering design and lab-scale evaluations currently underway. Proposed Year #3 work will incorporate necessary process and design improvements to upscale electrostatic fiber coating, fabricate a full-scale prototype for installation on a production-size fiber spinning unit (two threadlines), and experimentally evaluate its performance for uniformly coating nylon 6,6 carpet fibers on-site at the industry partner's plant.

 STATEMENT OF PROPOSED WORK

a)  Description of Critical Industry Problem

 This proposal responds to item 1, "Environment and Health: Reduction of Yarn Spin Finishes," in the carpet-related research needs identified in the TIP-PFFP FY2002/2003 Calls for TIP Proposals. Over-application of spin finish, largely done to compensate for coating non-uniformity, contributes to water and air pollution loads from carpet manufacturing. Excessive levels of COD in wastewater effluent is a serious problem for many carpet manufacturers in Dalton and other Georgia cities; yarn spin finishes typically contribute over 60% of this problem. Lowering the overall amount of finish applied to the fiber would correspondingly lower the COD entering wastewater and could obviate the need for costly alternatives available to carpet manufacturers for reducing discharge of COD from dyeing operations. Development of a more consistent spin finish application method would allow the use of lower finish level without loss of process efficiency.

b) Measurable Objectives for FY2003

1. Further refine the theoretical basis and mathematical model underlying charged-finish deposition onto high-speed dielectric filaments.

2. Upscale the electrostatic fiber-coating system incorporating necessary improvements in the process and prototype design.

3. Fabricate a full-scale prototype for installation on a production-size fiber spinning unit (two threadlines).

4. Experimentally evaluate the performance of the full-scale electrostatic-coating prototype for uniformly applying yarn spin finish to nylon 6,6 carpet fibers on-line at the industry partner's plant.

5. Transfer the technology and knowledge gained via formal reporting to TIP-PFFP, seminars and other technical presentations to the carpet industry and/or papers before professional societies, and, if warranted, patent applications.

c) Previous TIP-PFFP Research

Work proposed for FY2003 builds both indirectly and directly upon the results of projects previously funded by TIP-PFFP. In a 3-year completed project we investigated three different approaches to lowering COD levels in wastewater: 1) pretreatment of effluent by carpet manufacturers; 2) recovery and reuse of fiber finish at carpet manufacturing plants; and 3) optimization of the level of lubricant applied during carpet manufacturing. While each approach identified a partial solution for COD reduction, none was considered economically viable due to prohibitively large capital investments and operating costs. Other TIP-PFFP-funded work indirectly provides results scientifically supporting the need for our ongoing work; namely, experimental documentation that spin finishes significantly contribute to problematic emissions of VOCs from heat-setting processes.

More directly, our proposed FY2003 work is a third-year continuation of our TIP-PFFP-funded project which pursues source reduction rather than waste treatment to eliminate water- and air- pollution problems attributable to fiber spin finishes. Year #1 uncovered little prior published or industry-provided work regarding electrostatically-based individual-fiber coating on which to build. Year #2 therefore is currently refining the theoretical concepts and mathematical model we have developed specifically applicable to charged-finish deposition onto high-speed dielectric filaments, and identifying likely technical challenges to overcome in engineering design and lab-scale evaluations. Promising results from our theoretical/mathematical model typically predict maximum finish-to-filament electrostatic-deposition forces of attraction 12- to 146-times greater than gravitational force within the filament array of a threadline at a location several feet above the traditionally used finish "kiss roll" - depending on precharged conditions of both finish liquid and insulating filaments. At this intended threadline location for incorporating our process into a typical commercial nylon-spinning unit, the corresponding electrostatically-driven finish velocity transversely toward a filament is favorably predicted to be ~25% of the threadline's 15 m/s production speed, theoretically accomplishing deposition in much less than 1 ft of threadline travel. The proposed project Year #3 will build upon our current work in order to accomplish the upscaling of a reliable process and its full-scale prototype for the electrostatic application of spin finishes onto nylon filaments and its evaluation for coating effectiveness within the laboratory and on the industry partner's fiber-production line.

d) Other Related Work

DuPont and other fiber manufacturers have done work to improve the uniformity of application of spin finish during the fiber manufacturing process. Deposition of spin finish atomized by an ultrasonic horn was attempted by DuPont; the technique was determined to be impractical mainly because of the equipment cost and excessive non-target deposition.

AMTEX funded research and development work on application of dyes and chemical finishes to fabric using electrostatics. The project was conducted mainly at Oak Ridge National Laboratory. Apparently, the research was abandoned with the demise of AMTEX without proceeding to the demonstration stage. No individual fiber coating was attempted.

Literature searches and industry inquiries have provided little information on electrostatic fiber-coating work. While several attempts have been made at electrostatic coating of fabrics, webs, and other textile-surface substrates, the high-speeds and associated shear stresses and dielectric properties have apparently precluded successful application to polymeric fiber production.

Dr. Ed Law and colleagues in the Applied Electrostatics Laboratory at the University of Georgia have invented and commercialized technology for electrostatic application of chemical substances to agricultural crops. Finely atomized spray droplets of high charge-to-mass ratio (e.g., 10 mC/kg) are safely produced using charging voltages typically less than 2% those utilized in industrial systems. Similar electrostatic-charging methods may be applicable to spin finishes. Furthermore, the research team for this ongoing project is familiar with much additional research and development work done on applications of electrostatics in industrial processes ¾ many, such as electrostatic precipitation, routinely achieve deposition mass-transfer efficiencies of 99.9%. We are judiciously adapting appropriate approaches for fiber coating.

e) Industry Partner's Involvement

The industry partner currently serves a major role in providing technical information through its Fiber Surface Research Laboratory in Chattanooga, TN and test materials from its nylon 6,6 plant in Camden, SC. We consider it an important contributor to this TIP-PFFP project, especially in maintaining awareness of specific industry needs and technical constraints regarding the practicality of academic approaches and engineering designs. Following fabrication of the small-scale prototype for electrostatic application of fiber finish this current year, our industry partner will provide the site for pilot-scale experimental evaluations. The industry partner will also provide the test site and take a lead role during Year #3 in conducting the commercial-scale demonstration once technical feasibility of the process and prototype has been confirmed.

TECHNICAL APPROACH

 The Plan of Work for Year #3 will accomplish project objectives by focusing on the following tasks using the methods and procedures indicated.

1. Further refine and optimize the theoretical basis and mathematical model underlying charged-finish deposition onto the precharged high-speed, dielectric-filament array comprising the unconsolidated threadline bundle.

 a) Assess magnitudes of electrostatic-deposition forces achievable by simple Coulomb's law approach, space-charge field strategy, and applied-field approach, and optimize their combined beneficial effect for applying yarn finish.

 b) Assess and optimize the method and location along the threadline for imparting a unipolar surface precharge to individual filaments of the array.

 c) Assess and beneficially manipulate the charge-relaxation characteristics of both the finish liquid and the polymeric target filaments in order to maximize the electrostatic deposition and retention of finish, as well as to minimize any problematic residual net charge on the exiting coated-fiber bundle.

 d) Assess and remedy any possible electrostatic hazard vis-a-vis incendiary spark or personnel exposure.

 e) Assess and aerodynamically optimize mass-transfer of charged finish across the entrained boundary layer of high-speed air drawn along by the precharged filaments.

2. Upscale the electrostatic fiber-coating system incorporating necessary improvements in the

 overall process and prototype design.

 a) Size and secure all necessary equipment items specified in the design of a 50-60 lb/hr per threadline, two-threadline system for applying up to 1% wt. finishes onto nylon 6,6.

 b) Assess compatibility of all sub-system components (e.g., electrostatics, liquid metering, aerodynamic, mechanical, residual-charge neutralization, etc.) to ensure successful interfacing into an overall finish-coating system.

 c) Finalize geometrical aspects of the detailed engineering design of the prototype to ensure compatibility with, and ease of interfacing onto, the industry partner's commercial fiber-production unit.

3. Fabricate a full-scale prototype for installation on a production-size fiber-spinning unit (two

threadlines) as based upon the above refined engineering design and shop drawings. (Precision machining and electronic fabrication will be accomplished by U.Ga. Instrument Shop and by our research shop/technicians within the Driftmier Engineering Center.)

4. Experimentally evaluate the performance of the full-scale electrostatic-coating prototype for uniformly applying yarn spin finish to nylon 6,6 carpet fibers on-line at the industry partner's plant.

 a) Install system on-site at industry partner's plant in Camden, SC.

 b) Conduct on-site electronic measurements to confirm adequate levels of filament-surface precharge as well as finish-liquid charge at production speeds.

 c) Assess the on-site, long-term maintenance of electrostatic charging and deposition fields, insulator integrity and freedom from surface tracking due to any off-target deposition of finish within the full-scale coating system, etc.

 d) Assess possible occurrence of any other off-target deposition and/or airborne mist of finish in work environment and any unanticipated electrical hazard, and remedy as necessary.

 e) Assess the full-scale prototype's filament-coating deposition efficiency and uniformity achieved at production speeds utilizing methodologies/apparatus provided by industry partner's Fiber Surface Research Laboratory and others.

 f) Statistically analyze data on quantity and uniformity of finish electrostatically deposited by full-scale prototype and draw conclusions regarding any benefits as compared to conventional finish-application methods.

5. Transfer the technology and knowledge gained via formal reporting to TIP-PFFP, seminars

 and other technical presentations to the carpet industry and/or papers before professional

 societies, and, if warranted, patent applications.

 Most necessary laboratory facilities and equipment for FY2003 are currently available in U.Ga.'s Applied Electrostatics Laboratory and Textile Science laboratories. Industry facilities will

be relied upon for detailed analysis of the uniformity of fiber finish and for all on-site evaluations of our full-scale prototype.

PROJECT TEAM

This TIP-PFFP project on electrostatic application methods for yarn spin finish brings together highly qualified engineering and textile science faculty of the University of Georgia possessing unique technical competencies directly relevant to the defined problem area. Additionally, the project benefits by direct access to the university's extensive academic resources and facilities within its Applied Electrostatics Laboratory (AEL) and its Textile Science laboratories. Unique and invaluable expertise and pilot-scale fiber production and testing facilities are also made available for this work by the industry partner. A brief description of the project team follows:

. Dr. S. Edward Law(vita appended), Director of the AEL and team leader on this electrostatics-related project, is an internationally known expert in the field of electrostatics theory and applications for beneficial purposes. His credits include 16 domestic and foreign patents and over 100 published papers in electrostatics and related areas. Dr. Law actively contributes to engineering/electrostatics professional societies, currently serving as Fellow - Institute of Electrical and Electronics Engineers, Vice President - Electrostatics Society of America, and Member - National Academy of Engineering, an honor bestowed on only the highest achievers in the field of engineering. He also recently served as acting Editor-in-Chief of the internationally based Journal of Electrostatics (Elsevier Publishers).

. Prof. Warren S. Perkins(vita appended) serves with Dr. Law as co-leader of the research team. He is highly respected in both the academic setting and the textile/carpet industry, having over 30 years faculty-level experience at Auburn University and the University of Georgia directing and coordinating research projects. Prof. Perkins has served as President of the American Association of Textile Chemists and Colorists and recently was awarded both their Olney Medal for "Achievements in Textile Chemistry" and their Chapin Award for lifetime service. He currently serves as Technical Editor for Textile Chemist and Colorist Magazine.

. Dr. Timothy P. Blatchford, Senior Research Chemist in the DuPont Fiber Surface Research group at Chattanooga, serves as the primary contact for the industry partner of this TIP-PFFP project. He is a recognized industry expert in fiber finish formulation and application. Dr. Blatchford coordinates the industry partner's participation including providing nylon and finish test materials, assistance in measuring finish uniformity, facilitating pilot-scale trials and prototype demonstrations, and all other on-site activities.

SCHEDULE

 The proposed Project Year #3 will build upon our current work by developing an appropriate process and full-scale prototype for the electrostatic application of spin finishes onto nylon filaments, and by evaluating its coating effectiveness within the laboratory as well as on the industry partner's pilot-scale fiber-production system. We intend to accomplish the design refinement and upscaling necessary to install a test system on a commercial two-threadline fiber spinning unit. The timeline for the Year #3 activities follows as denoted by task numbers given earlier under TECHNICAL APPROACH.

 Table 1. Timeline for Major Tasks during FY2003.

2002 - 2003

J

A

S

O

N

D

J

F

M

A

M

J

1

2

3

4

5

Spin finishes applied by synthetic fiber producers and carpet manufacturers typically contribute over 60% of the pollution problem (COD) associated with wastewaters from Georgia's carpet industry. Due to lack of coating uniformity achievable by present-day application methods, excess finish is usually applied to ensure satisfactorily lubricated travel of yarn through subsequent carpet-manufacturing stages. Instead of addressing this environmental pollution problem by traditional, but costly, wastewater treatment methods, University of Georgia engineering and textile researchers are developing highly efficient electrostatic-deposition processes and prototypes to improve spin-finish coating and thereby provide for significant abatement of this water pollution problem at its source. This industry-driven research and development is collaboratively supported by the University of Georgia and the Georgia Traditional Industries Program under the Traditional Industries Program for Polymer, Fiber and Fabric Properties (TIP-TIP-PFFP).

APPENDIX

Brief Biographical Information

 S. Edward Law received the B.S., M.S. and Ph.D. degrees in Biological and Agricultural Engineering from North Carolina State University with minors in mathematics and physics. He conducted research into light-scattering properties of optically-dense biological-particulate systems in a Washington, D.C. instrumentation laboratory as a National Academy of Sciences Postdoctoral Fellow. He gained further industrial research experience in charged-particulate technology and electrogasdynamics as engineering project leader with Gourdine Environmental Systems, Inc. in New Jersey. He joined the University of Georgia Biological and Agricultural Engineering faculty in 1970, now holds the academic rank of Brooks Distinguished Professor, and is responsible for research and development of electrostatics for agricultural and biological applications as Director of the Applied Electrostatics Laboratory.

Dr. Law is a member of the American Society of Agricultural Engineers, the Institute of Electrical and Electronics Engineers, the Electrostatics Society of America, the International Ozone Association, the Institute of Liquid Atomization and Spray Systems, the Entomological Society of America, Sigma Xi, Tau Beta Pi and Phi Kappa Phi. He has been awarded the Creativity in Research Medal by the University of Georgia Research Foundation as well as its Inventor of the Year Award, and has received from his college the Brooks Award for Excellence in Research. Professor Law's engineering developments have been awarded sixteen domestic and foreign patents, and his peer-reviewed scientific publications have received eight Superior Paper Awards (top 2½%) from the ASAE and the IEEE. He is a Fellow in ASAE and has received its Cyrus McCormick Gold Medal Award . . . for exceptional and meritorious engineering achievement in agriculture. He has also has been elected to Fellow in IEEE. . . "for contributions to electrostatics technology for agricultural and biological applications". . . (selection limited to 0.1% of international membership annually). In 1996 he was elected as a member of the National Academy of Engineering. The Electrostatics Society of America presented him its Lifetime Achievement Award in 1998.

Warren S. Perkins received the B.S. and M.S. degrees in Textile Chemistry from Clemson University. He gained further industrial research experience through short-term consulting services for over 20 textile and chemical companies. He has a current contract with Procter and Gamble Company. He was a faculty member in the Textile Engineering Department of Auburn University for 26 years. He then joined the University of Georgia's Textile, Merchandise & Interiors faculty in 1995, now holds the academic rank of Georgia Power Company Professor of Textile Sciences, and is responsible for research and development of: textile chemical process improvements in dyeing and chemical finishing of textile materials; textile manufacturing process developments that reduce water pollution; and properties of sizing materials for yarn.

Prof. Perkins served for two continuous years as President of the American Association of Textile Chemists and Colorists. He served as Technical Editor for America's Textiles International Magazine and is the current Technical Editor at Textile Chemist and Colorist Magazine. He has been awarded the Harold C. Chapin Award, highest award given for lifetime service to the American Association of Textile Chemists and Colorists as well as its Louis Atwell Olney Medal for lifetime Achievement in Textile Chemistry. Professor Perkins has been awarded two domestic and foreign patents, has published over 100 articles in journals and symposia proceedings, made presentations at more than 100 technical and professional meetings, and published a textbook.

Industry Partner's Letter of Support

PROJECT TITLE: Electrostatic Application of Yarn Spin Finishes for Carpet Manufacturing

Attn: Charles Estes - TIP-PFFP/Carpet Research Program Administrator

Dr. S. Edward Law and Prof. Warren S. Perkins, University of Georgia, are submitting a FY2003 continuation proposal under the state of Georgia's TIP-PFFP industry-driven program to investigate the electrostatic application of spin finishes in fiber production.

Spin finishes used in making carpet fibers contribute to environmental problems, especially around the Dalton, GA area. While DuPont has reduced this amount of spin finish applied to its manufactured carpet fibers roughly 50% over the past 5 years, we believe this technology may be a route to reduce it even further. More effective use of spin finishes will also reduce cost and alleviate numerous other process complications. Additionally, this technology could impact other fiber/textile products and processes throughout the industry.

We are very supportive of the program proposed by Dr. Law and will work with him by providing fiber samples and testing technology that may be discovered under this proposal. During next year we expect Dr. Law to demonstrate a prototype for collaborative testing in our plant. We urge you to approve funding.

Dr. Timothy P. Blatchford
DuPont Nylon
Fiber Surface Research Laboratory
Chattanooga, TN
(423) 875-7655
Timothy.P.Blatchford@usa.dupont.com