AT-LINE PROCESS CONTROL OF THE MOISTURE AND FINISH-ON-FIBER OF TEXTILE PRODUCTS BY NIR

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1 JPACSM 64 AT-LINE PROCESS CONTROL OF THE MOISTURE AND FINISH-ON-FIBER OF TEXTILE PRODUCTS BY NIR James E. Rodgers Solutia, Inc., Gonzalez, FL, Pan Sukpaladisai Solutia, Inc., Decatur, AL, Rafael Barraza Solutia, Inc., Gonzalez, FL, Chuck Horton Solutia, Inc., Greenwood, SC, KEYWORDS: INFRARED, AT-LINE, TEXTILES, MOISTURE, FINISH-ON-FIBER (FOF), TIRE YARN, CARPET YARN ABSTRACT The moisture content and Finish-On-Fiber (FOF, the quantity of finish applied to the surface of textile fibers) are important process and quality control variables that can significantly impact physical properties, manufacturing processes, quality, and productivity. The rapid detection and identification of outlier moisture and FOF bobbins during production is of paramount importance to several in the textile industry. In this work we demonstrate the feasibility of at-line moisture and surrogate process FOF analyses using a portable, noncontact NIR moisture analyzer, in which these fiber properties are measured directly on the surface of nylon tire and BCF carpet yarn bobbins. NIR moisture and surrogate calibrations were developed for tire and BCF carpet products (different products, denier/size, tint/ color, etc.). The NIR method rapidly and accurately measured moisture differences, directly on the bobbin surface, between tire and carpet bobbins at various laboratory and manufacturing locations. A strong correlation was verified between NIR bobbin moisture and FOF as the finish emulsion is applied to the bobbin in spinning. FOF outlier bobbins were rapidly and accurately detected by the at-line NIR analysis, preventing contamination of downstream processes. The impacts of yarn parameters, measurement location, and environmental and operational conditions on the NIR surrogate FOF results were minor and manageable. INTRODUCTION The moisture content and the quantity of finish applied to the surface of textile fibers (Finish-On-Fiber, or FOF) are often critical and important process and quality control variables. The moisture level in nylon, when combined with the influence of temperature and heating time, can dramatically impact the fiber s morphology. 1,2 Finish is a lubricant (i.e., an oil-in-water emulsion) that is often added to textile fibers to assist their internal performance and the fiber s processing downstream. 2-5 A small amount of finish is added to the surface of textile fibers for fiber lubrication, cohesion, and static protection. FOF is the quantity of finish applied to the fiber surface. The moisture content and FOF of nylon textile products can significantly impact physical properties, manufacturing processes and quality, and productivity. A very common means for measuring the moisture of textile products is by thermal weight-loss techniques (i.e., a Brabender or oven). The FOF applied to the fiber is normally measured separately for fiber products by several techniques solvent extraction, Near InfraRed (NIR), Nuclear Magnetic Resonance (NMR), etc. 2,6 A recurring problem in the production of textile bobbin products is the difficulty in rapidly detecting and identifying outlier moisture and FOF positions during production in spinning and downstream. Non-contact, atline moisture and FOF measurements directly on the bobbin in manufacturing would result in improvements in process monitoring, Quality Assurance, and potential cost savings. NIR spectroscopy analyses are used extensively in the chemical, polymer, and textile industries, and their use and importance is growing. Typically, the NIR spectral region is from nm, and its absorbance bands consist primarily of overtone and combination bands. 7 Linear regression techniques and advanced chemometric analyses are used to develop NIR calibration equations for the property of interest (NIR absorbance at specified wavelength(s) or spectral regions vs. the concentration of the property of interest). The OH absorbance bands due to water/moisture are very strong in the NIR spectral region, especially at ~1450, 1940, and 2250nm. The FOF absorbance bands are related to the organic finish material present in the finish. NIR analyses have been used often in the past for moisture and FOF

JPACSM 65 analyses on several textile products 2, 8-11, but the analyses have been primarily with expensive multi-nir filter or scanning NIR systems in a laboratory or on-line mode.

2 JPACSM 65 analyses on several textile products 2, 8-11, but the analyses have been primarily with expensive multi-nir filter or scanning NIR systems in a laboratory or on-line mode. In this work, a 3 phase program was implemented to investigate 1) the feasibility of using a portable, non-contact, low cost (relative to scanning systems), single NIR filter moisture analyzer to measure moisture at-line, directly on tire and carpet yarn bobbins in manufacturing, 2) the feasibility of the using the portable NIR unit as a surrogate, at-line process monitoring measurement of bobbin FOF during spinning, and 3) the impact of yarn parameters, location, and environmental/operational conditions on the NIR results. 11 EXPERIMENTAL Instrumentation Portable NIR The Kett KJT100 NIR Moisture Analyzer is a portable, hand-held, light-weight OH-specific NIR analyzer that can perform fast, semi-quantitative, noncontact moisture analyses on static AND moving samples. 12 The unit contains one wide-band NIR filter for moisture (1940nm, OH-sensitive filter). The NIR measurement is very fast (<1 minute), contains an internal "targeting"/sample distance system, and can auto correct for manufacturing environments. The correct focal length/measurement distance from the sample is based on 2 overlapping color circles than shine on the sample surface; the sample is ready to measure when the small red circle is inside the large white circle. The overlapping circle method results in a very flexible system that does not require exact distances from the sample to the unit. (Figure 1) Figure 1. Example of a typical at-line NIR analysis Brabender Moisture The Semi-Automatic Brabender Rapid Moisture Tester is a thermal weight-loss moisture tester that can that heat simultaneously and measure sequentially up to 10 samples at one time. The sample is heated at 110 O C for 45 minutes, then read on the Brabender tester. The moisture content of the nylon fiber is the difference in the weight of the fiber before and after heating. Bench-top NMR FOF FOF was measured on the Oxford QP20+ benchtop NMR analyzer. 6,13 The QP20+ is a bench-top, wide band 20MHz NMR analyzer, with 125mm diameter magnet faces and 18mm diameter (8.5mL volume) proton sample probes. The NMR measures the total proton content of the fiber sample as a function of time. Using the spin-echo technique, the total proton content of the nylon fiber at a specified decay time (i.e., 2 ms) is related to the FOF content of the fiber. Several NMR scans are obtained to yield an average NMR result. The analysis time for the laboratory NMR analysis is very fast (~30 seconds per sample). Materials Nylon66 bobbins of Solutia both tire yarn and Bulked Continuous Filament (BCF) carpet bobbins for several product types were analyzed in these trials. The samples sets for both product lines covered both wide moisture and FOF ranges and routine production samples. Wide range samples were used to optimize the at-line NIR calibrations for moisture and/or FOF for each product type. The calibrations were verified using a separate set of wide range bobbins and validated on routine production samples. The wide range samples were used to verify the NIR calibration transference and to demonstrate the ease of calibration with the NIR system. The wide range and routine samples were evaluated in the laboratory and/or on the manufacturing floor in order to evaluate the at-line NIR method s ability to detect critical changes in moisture and /or FOF and to evaluate the influence of environmental factors (laboratory versus manufacturing area) on the NIR results. Methodology The program consisted of the following 3 Phases: Phase I. NIR moisture content calibrations were developed with bobbins of wide moisture ranges for tire yarn products. This phase included atline NIR and Brabender moisture measurements on doffed spun tire yarn bobbins at several locations in the Manufacturing processes.

3 JPACSM 66 Phase II. Feasibility evaluations were performed on the potential to use the spun fiber moisture analysis as a surrogate measurement for bobbin FOF in spinning. For spun fiber production, FOF normally changes in the same direction as the spun bobbin moisture. A strong correlation between on-the-bobbin moisture and the bobbin FOF during spinning would indicate a high probability of using the NIR analyzer as a surrogate, direct-read FOF monitor. At-line moisture and surrogate FOF measurements were performed on tire yarn and BCF carpet bobbins while in the spinning process (just after finish application to the fiber surface), in which the NIR results from wide-range moisture and FOF factorial samples and from routine production samples were compared and correlated to the corresponding Brabender moisture and/or NMR FOF. Phase III. The impact of yarn parameters, location, and environmental/operational conditions on the at-line NIR FOF results were evaluated on several BCF carpet yarn products different denier, different finishes, tint/no tint, different spinning machines and plant locations, etc. Four products were evaluated CA (purpletinted bobbins, denier/size A, finish A, machine A), CB (no tint bobbins, denier B, finish B, machine B), CC (no tint bobbins, denier A, finish A, machine B), and CD (no tint bobbins, denier C, finish B, machine A). Machine B was in a different operational location from machine A, with different environmental and operational conditions. Data Analysis NIR moisture and/or surrogate FOF averages were obtained for each bobbin. The NIR results were compared to the Brabender thermal weight loss moisture and/or the laboratory FOF results. The initial criterion for moisture method agreement (NIR-Brabender) was +/- 0.50% moisture for over 80% of the samples evaluated, and the initial criterion for FOF method agreement (NIR- NMR) was +/- 0.15% FOF for over 80% of the samples evaluated. RESULTS AND DISCUSSION Phase I NIR and Brabender thermal weight loss moisture evaluations were performed on doffed tire yarn bobbins located in the laboratory and at 2 manufacturing locations--the yarn lag and first floor spinning. The NIR analysis was very fast analysis time for 3 measurements was <1 minute per static bobbin. Excellent agreement between the NIR and thermal moisture results were observed for samples conditioned in the laboratory, with the NIR-Brabender agreement being within +/- 0.50% moisture for over 95% of the samples. The NIR-thermal moisture agreements for bobbin samples taken in the manufacturing areas were also very good. After the manufacturing area bobbins had aged 24 hours in the laboratory (reach equilibrium moisture), the samples were analyzed again. Excellent method agreement was observed for the aged equilibrium samples. A slight bias was observed between the NIR bobbin measurements in the manufacturing areas and the thermal moisture results. (Table I for an example) Phase II Evaluations were conducted on factory bobbins of spun tire yarn with wide moisture and FOF ranges (~2-6% moisture and ~0-1.65% FOF) to determine the feasibility of the NIR analyzer to serve as a surrogate FOF analyzer as well as a moisture analyzer. The moisture and/or surrogate FOF analyses were performed at-line, directly on the moving bobbin surface, during the spinning process. The at-line measurement location was in the spinning area, just after application of the finish during the take-up of the fiber threadline on the bobbin. The NIR unit successfully measured moisture and performed as a surrogate at-line, Process Control measurement of tire yarn FOF on bobbins during spinning. Excellent NIR moisture-lab FOF agreement was obtained. (Figure 2) For routine production samples, the overall method agreement between the at-line NIR moisture results and lab FOF was very good. Several manufacturing upsets and outlier FOF positions in spinning were quickly and accurately identified at-line by the NIR moisture analysis. Repeat outlier positions were readily identified by the NIR unit, and this outlier position capability permitted the detection of chronic bad positions on the machine. Although FOF outliers could be detected and identified by the NIR moisture results, the use of a NIR measurement was desired that yielded FOF results instead of a moisture results to be correlated to an approximate FOF value. The use of a surrogate FOF result would minimize operator error and provide direct, on-the-spot correlation of the NIR result to a FOF value. A new NIR calibration was developed to yield the surrogate FOF directly, using the NIR absorbance and lab NMR FOF values. The calibration was evaluated on routine production bobbins during spinning for 3 tire yarn products, and very good agreement was observed between the NIR surrogate FOF and the lab FOF. (Figure 3)

4 JPACSM 67 Table I Portable NIR vs. Lab Brabender moisture comparisons, Manufacturing area and aged 24 hours in the Lab. S MANUFACTURING AREA LAB (24hrs age) NIR BRABENDER DELTA (B-N) NIR BRABENDER DELTA (B-N) AVG SD This bias was easily adjusted with the NIR moisture calibration. NIR H 2 O (%) H2O FOF (NMR) Figure 2: NIR Moisture Laboratory FOF Relationship, Spun Tire Yarn ARE UPPER AND LOWER LIMITS LAB NIR NIR MOISTURE (%) MOISTURE (%) Figure 3: Moisture FOF Comparison: NIR Moisture-NIR Surrogate FOF-Laboratory FOF.

5 JPACSM 68 The surrogate FOF NIR results tended to yield overall better agreement to the lab FOF than observed with the NIR moisture results. The surrogate FOF results were also less noisy during the analysis of the moving bobbin, reducing analysis time. In addition, several manufacturing upsets (bad or outlier finish pumps or positions) in spinning were quickly and accurately identified at-line with the NIR surrogate FOF analysis. The at-line surrogate FOF analysis with the NIR analyzer was expanded to BCF carpet products. Product CA (purple-tinted bobbins, denier A, finish A, machine A) was selected as the first or base BCF bobbins for initial trials. NIR surrogate FOF calibrations were developed for CA, with excellent method agreement was observed between the NIR absorbencies and lab FOFs. Several routine production bobbins of CA and 1 prepared low FOF outlier bobbin were analyzed with the NIR surrogate FOF calibration and compared to the lab FOF results. Very good FOF method agreement was observed between the NIR and lab FOF results. All NIR surrogate FOF results agreed to within +/-0.10% of the lab FOF results (Figure 4), and the outlier bobbin was rapidly and readily detected by the NIR unit. Phase III Phases I and II had shown that the portable NIR unit could successfully monitor fiber moisture both in the laboratory and at-line in the manufacturing areas and could successfully serve as a surrogate at-line FOF measurement during the spinning process, with FOF process outliers readily and quickly identified for the sample sets evaluated. Of immediate interest was the flexibility and versatility of the at-line surrogate FOF measurement for different product types and yarn systems what were the impact(s) of yarn parameters, location, and environmental/operational conditions on the at-line NIR surrogate FOF results. The investigations were extended to 3 additional BCF carpet products in addition to set CA CB, CC, and CD. These 3 new BCF carpet sample sets differed from the initial BCF set CA by finish type, tint vs. no tint on the bobbins, yarn denier, production machine, and/or combinations of these differences. The second trial was on BCF set CB (no tint bobbins, denier B, finish B, machine B). Denier B (yarn size) was twice denier A, and machine B was located in a different operational area from machine A. NIR surrogate FOF calibrations were developed for set CB, and excellent linearity was observed between the NIR FOF and lab FOF results. Several routine production bobbins and 2 prepared low FOF outlier bobbins of CB were analyzed for FOF by the NIR. Very good FOF method agreement was observed between the NIR and NMR results. (Figure 5) The outlier bobbins were rapidly and readily detected. Although the absolute NIR calibration equations were different for CA and CB, they were very similar in nature and response. These similarities in equation and response between two BCF products with very different yarn parameters, in addition to the response obtained for the tire yarn products, demonstrated the flexibility and versatility of the NIR method. The next trial was on BCF set CC (no tint version of sample CA produced on machine B). A linear NIR surrogate FOF calibration was developed. (Figure 6) It was interesting to note that excellent calibration statistics were also obtained with the NIR calibration for set CA, with only a slight bias required to offset the effect of tint and/or machine differences. For both calibrations, method linearity was excellent. Routine production bobbins and 2 prepared low FOF outlier bobbins of CC were analyzed with the adjusted CA equation for FOF. Once again, very good FOF method agreement was observed between the NIR and lab results (Figure 7), with the outlier bobbins rapidly detected. These results demonstrated that the impacts of tint and/or operational and environmental conditions were small. The final trial was on BCF set CD (totally different product from CA that was produced on machine A no tint, finish B, denier C). Denier C is slightly smaller in size (~20%) than denier A. A linear NIR surrogate FOF calibration was developed, with excellent method linearity. It was interesting to note that the slope and intercept for CD were very similar to that obtained for the purple-tinted CA bobbins. When the CA calibration for surrogate FOF was evaluated on routine CD production bobbins and 3 prepared low FOF outlier bobbins, very good FOF method agreement was observed between the NIR and lab results. These results demonstrated that the impacts of small denier and finish type differences for similar products were small, especially of the products that were produced under the similar operational parameters.

6 JPACSM NIR FOF LAB FOF Figure 4: NIR Surrogate FOF Laboratory FOF, Routine Production Bobbins, BCF Carpet Yarn CA NIR FOF LAB FOF Figure 5: NIR Surrogate FOF Laboratory FOF, Routine Production Bobbins, BCF Carpet Yarn CB. NIR ABS, YARN CC BCF YARN CA "TINTED" NIR FOF BCF YARN CC LINEARITY (NIR ABS - LAB FOF) LAB NIR FOF, TINTED YARN CA (% Figure 6: NIR Surrogate FOF Laboratory FOF, Carpet Yarn CC (No Tint Version of Yarn CA on Machine B).

7 JPACSM ADJ CA NIR FOF LAB FOF Figure 7: NIR Surrogate FOF Laboratory FOF, Routine Production Bobbins, BCF Carpet Yarn CC. CONCLUSIONS Using the portable NIR analyzer, we developed and verified the flexibility and versatility of the portable NIR unit s ability to rapidly and accurately monitor the moisture and surrogate FOF level on spun tire yarn and BCF carpet yarn bobbins from the laboratory to at-line in the manufacturing area during the spinning process. For tire yarn moisture, the NIR unit successfully monitored moisture differences between bobbins in several manufacturing areas (spinning-lag-lab), with over 95% of the bobbins agreeing within the desired +/-0.50% moisture between the NIR and thermal weight-loss methods. Surrogate FOF calibrations were developed for the at-line NIR measurements of FOF for spun tire yarn and BCF carpet yarns. Very good overall method agreement was observed between the NIR and laboratory FOF results. Of critical importance to the manufacturing area was the rapid at-line identification of several outlier bobbins of low FOF due to manufacturing upsets, preventing their contamination of downstream processes. For all BCF carpet sample sets, over 90% of the bobbins agreed within the desired +/-0.15% FOF between the NIR and lab FOF. Next, the impact of yarn parameters, location, and operational conditions on the atline NIR surrogate FOF results were evaluated on several BCF carpet products. The base product was purple-tinted carpet yarn CA, and its results were compared to 3 additional BCF carpet products CB, CC, and CD (different finish type, tint vs. no tint on the bobbins, yarn denier, production machine, and/or combinations of these differences). NIR surrogate FOF calibrations were developed, and very good to excellent NIR-lab FOF method linearity for all 4 products. In all cases, FOF outliers were rapidly and accurately detected by the atline NIR analysis. The impact of yarn parameters (tint, denier, finish type), manufacturing location, and environmental/operational parameters were slight and manageable. ACKNOWLEDGMENTS The authors wish to acknowledge and express our thanks to Ms. Alice Skoufis and Mr. Bob Aaron of Solutia-Pensacola and Dr. Gordon Mayfield, Ms. Carmen Meredith, and Messers. Check Helms and Don Livingston of Solutia-Greenwood for their superb assistance in the analytical measurements and process support in the production of the bobbin sample sets. REFERENCES 1. J. Saunders, Polyamides, Fibers, Encyclopedia of Textiles, Fibers, and Nonwoven Fabrics, ed. M. Grayson, New York: John Wiley and Sons, 347 (1984). 2. S. Ghosh and J. Rodgers, NIR Analysis of Textiles, Handbook of Near-Infrared Analysis, Ch 22, eds. D. Burns and E. Ciurczak, New York: Marcel Dekker, Inc., 589 (2001). 3. H. Billica, Fiber Producer, April, 21 (1984). 4. R. Crossfield, Fiber World, March, 21 (1980). 5. C. King, Fiber Producer, October, 17 (1980). 6. J. Rodgers, Spectroscopy, 9 (8), 40 (1994). 7. D. Burns, Modern Near InfraRed Reflectance Analysis, ACS Short Course, New Orleans, LA (1985). 8. J. Rodgers, Specific Applications of NIRA in the Textile Industry, Proceedings 7 th International NIRA Symposium, Technicon Technical Center, Tarrytown, NY (1984). 9. B. Hill, Evaluation of a NIR Measuring Process for Sewing Thread, AATCC Textile Applications of NIR Technology Symposium, Asheville, NC (1993).

8 JPACSM J. Harper, Applications of Near Infrared Reflectance Spectroscopy to Rayon Yarns, AATCC Textile Applications of NIR Technology Symposium, Asheville, NC (1993). 11. J. Rodgers, et. al., Process Monitoring of the Moisture and Finish-On-Fiber of Textile Products Using a Portable Near InfraRed (NIR) Analyzer, PittCon 2002, New Orleans, LA (2002). 12. Operation Manual for the Kett KJT100, Kett USA, Villa Park, CA. 13. Operation Manual for the Oxford QP20+ NMR Analyzer, Oxford Instruments, Concord, MA.

Easier, faster, more accurate quality assurance. Next generation benchtop NMR, today.

Easier, faster, more accurate quality assurance Next generation benchtop NMR, today. WHAT DOES THE MQC + ANALYSER DO? The MQC + analyser measures oil, water, fluorine and solid fat in a variety of samples