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CHARACTERIZATION OF SURFACE FINISHES ON TEXTILES BY IN-LINE NIR CHEMICAL IMAGING
3rd OCM Karlsruhe , 22-23. März 2017
Gabriele Mirschel,1 Olesya Daikos,1 Tom Scherzer,1 C. Steckert2, K.Heymann1
1 Leibniz Institute of Surface Modification (IOM), Leipzig, Germany2 LLA Instruments GmbH, Berlin, Germany
2
3rd OCM, Karlsruhe, March 22-23, 2017
Motivation
Germany is global market leader in the production of technical textiles (polyester, polyamid or cotton)
Working widths up to 4 m
Typical applications: Materials for automotive (roof-liner or seat cover), ink-jet printing (banners), curtains, functional clothing, …
Wet-chemical surface finishing of textiles Coating weight, homogeneity
Finishes: Stiffening, flame retardant, wett-able, hydrophobic, stain-resistant, anti-static, brightening, …
Well-established production processes, butnowadays with very high quality require-ments Process monitoring necessary
Residual moisture of textiles after drying
Detection and identification of contaminants
3
3rd OCM, Karlsruhe, March 22-23, 2017
Surface Finishing of Textiles
Finishes
Optical brighteners
Flame retardants
Hydrophobizing agents
Stiffening agents
…
Sizes
Improve the processabilityon textile machines
Have to be removed before the further processing steps
Textiles
Polyester
Cotton
Wet-Chemical Treatment
Process Steps
Treatment in aqueous disper-sion
Squeezing in a foulard
Drying and heat setting
Objectives of Chemical Imaging
Applied quantity (finishes)
Cleanness (sizes) extremely impor-
tant for further processing
Homogeneity
Detection and identification of impuri-ties: oil, grease, processing agents, … (often poorly visible)
Degree of dryness
…
4
3rd OCM, Karlsruhe, March 22-23, 2017
Highlights
Quantification of Flame Retardants
Monitoring of Desizing/Cleaningness of Textiles
Identification of Contaminants
Monitoring of the Moisture Content
5
3rd OCM, Karlsruhe, March 22-23, 2017
NIR Camera System
Mounting of the NIR camera above a conveyor belt at IOM
KUSTA1.9 MSI (LLA Instruments, Berlin, Germany)
InGaAs sensor, TE-cooled
192 x 96 pixel (spatial x spectral resolu-tion)
Spectral range 1320-1900 nm(option: 1280-2200 nm)
NIR objective 15 mm/2.0 (Specim)
Lateral resolution ~2.6 mm
Frame rate max. 795 Hz
Illumination unit with 8 NIR lamps (120 W)
Conveyor belt with a highly absorbing black PUR coating (width 0.5 m, 2-60 m min-1)
Working width up to 1000 mm ( vertical
mounting distance 1 m)
6
3rd OCM, Karlsruhe, March 22-23, 2017
Calibration Process
1300 1400 1500 1600 1700 1800 1900
0.0
0.2
0.4
0.6
0.8
1.0
untreated
4.6 g m-2
13.19 g m-2
25.65 g m-2
39.80 g m-2
51.31 g m-2
Reflectivity
Wavelength [nm]
Fig. 1: NIR spectra (normalized) of PES fabric
untreated and treated with a flame retardant.
Aminourea: CH5ON3
N-H asymmetric and N-H symmetric
combination vibration at 1500 nm
NIR Imaging = indirect method
calibration is necessary
Samples with a coating weight from
5-52 g/ m-2 were prepared
(sample size 30 x 40 cm)
Random 5000 spectra of each
sample were taken + related to
corresponding coating weights
Various preprocessing methods
were applied
PLS model with lowest RMSEP and
highest R2 was choosen
7
3rd OCM, Karlsruhe, March 22-23, 2017
Calibration – Flame retardant on PES fabric
6.8 6.9 7.0 7.1 7.2 7.3
-0.15
-0.10
-0.05
0.00
0.05
0.10
0.15
0.20
0.25
untreated
4.6 g m-2
7.6 g m-2
13.2 g m-2
25.6 g m-2
39.8 g m-2
51.3 g m-2
Score
s P
C2
Scores PC1
Fig. 2 : Scores plot PC2 against PC1 of
samples with and without flame-retarding
agent.
0 20 40 60
0
20
40
60
EV 3
RMSEE 1.78 g m-2
Bias -0.014 g m-2
SEC 1.78g m-2
RMSEP 2,07 g m-2
Bias 0.524 g m-2
SEP 2.01 g m-2
R² 98.67 %
r² 0,9933
Pre
dic
ted C
oating W
eig
ht
[g m
-2]
Gravimetrical Coating Weight [g m-2]
Fig. 3: PLS regression of a calibration
model for the coating weight of a flame
retardant on PES fabric.
RMSEP in external validation: 4.2 g/m²
8
3rd OCM, Karlsruhe, March 22-23, 2017
Manual Wet-Chemical Treatment of Textiles
Chemical images of a polyester fabric (194 g/m²), provided with a flame retardant based on phosphates and amidourea
Coating weights:10.8 g/m² (left) und 20.4 g/m² (right)
Coating weights:15.5 g/m² (left) und 26 g/m² (right)
Distribution of a flame retar-dant on cotton
Distribution of a flame retar-dant on polyester fabric
9
3rd OCM, Karlsruhe, March 22-23, 2017
Wet-Chemical Treatment of Textiles
Laboratory-scale foulard for well-defined squeezing of wet textile samples
Coating weight 13.2 g/m²
Coating weight 26.3 g/m²
Coating weight 43.1 g/m²
Chemical images of a polyester fabric, provided with a flame retardant on a foulard
RMSEP in external validation:
2.1 g/m²
Blots result from dried droplets of the flame retardant dripped to the squeezed textile
Tracks result from pinning-on
10
3rd OCM, Karlsruhe, March 22-23, 2017
Desizing / Washing of Textiles
Coating weights: 5.3 g/m² (top)0.4 g/m² (bottom)
RMSEP 0.4 g/m²Detection Limit
Sizes
Improve the processabilityon textile machines
Can strongly affect further processing such as printing, finishing, lamination, …
Have to be completely removed before the further processing steps
Distribution of fatty acid ethoxylate used as size on a polyester fabric before and after desizing
11
3rd OCM, Karlsruhe, March 22-23, 2017
Detection of Blots of Contaminants
Finishes, sizes, oils, greases, processing agents, etc.
May drop on the textile web during processing
In most cases, dried blots are invisible in the VIS region
Blots can strongly affect further processing such as printing, finishing, lamination, …
Detection and identification by chemical imaging
Differentation between mineral oil and silicon grease (synthetic)
=> PCA analysis
Identification of various oils and greases on a cotton fabric
NIR spectra of oils and greases
1300 1400 1500 1600 1700 1800 1900
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
Re
fle
ctivity a
.u.
Wavelength [nm]
Cotton Fabric
Machine Oil
Vacuum Grease
Silicon Grease
12
3rd OCM, Karlsruhe, March 22-23, 2017
Determination of Contaminants
Dried droplet of a fatty acid ethoxylate used as size on a polyester fabric
Blot of a size based on amixture of paraffin andpolyethylene on a polyesterfabric
Detection of invisible traces of various textile finishing agents on cotton
Cotton
PVAc (Stiffening)
Phophate+ Amidourea (Flame Retardant)
Styryl Benzene (Brightener)
Phosphate (Flame Retardant)
13
3rd OCM, Karlsruhe, March 22-23, 2017
Drying of Textiles – Preliminiary Test
25 sec30 sec
20 sec
Drying of cotton fabric using a flat iron (preliminary test, semiquantitative data: distance in the scores plot)
DryAlmost dry
Wettish
Dampish
Very wet
Saturated1400 1500 1600 1700 1800 1900
0.0
0.2
0.4
0.6
0.8
1.0
Inte
nsity
Wavelength [nm]
0.5%
5%
11%
17%
24%
32%
59%
100%
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3rd OCM, Karlsruhe, March 22-23, 2017
Drying of Textiles
36 % r.H.
46 % r.H.
62 % r.H.
Chemical images of polyester fabric with different moisture contents (after 30 min in a conditioning cabinet)
RMSEP in external validation:
2.9 %
Sample
relative
Humidity
[%]
relative
Humidity
NIR
[%]
Difference
[%]
1 36 37.2 1.2
2 45 47.1 2.1
3 55 56.6 1.6
Temperatur ~ 60°C
15
3rd OCM, Karlsruhe, March 22-23, 2017
In-line Monitoring of the Moisture at a Stentering Frame
100 %
0 %
In-line monitoring of the moisture con-tent of a polyester web pinned on a sten-tering frame in the Textile Research In-stitute (TITV) Greiz after spraying wateron the fabric
16
3rd OCM, Karlsruhe, March 22-23, 2017
Summary
Coating weight and homogeneity of layers applied by wet-chemical surface finishing of textiles
Precision (RMSEP): ca. 1…2 g/m² depending on the
specific system
Residual amounts after washing of textiles
Detection limit ~0.5 g/m²
Detection and identification of contaminants
Determination of the residual moisture of textiles
Precision (RMSEP): < 3 % (preliminary tests only)
Objective: In-line monitoring of textile production processes
* G. Mirschel, O. Daikos, T. Scherzer, C. Steckert, Anal. Chim. Acta 932, 69-79 (2016)
17
3rd OCM, Karlsruhe, March 22-23, 2017
Acknowledgments
Udo Trimper (IOM)
Manfred Hinkefuß (IOM)
Andreas Neudeck
Hans-Jürgen Weiß
TITV Textile Research Institute, Greiz
C.H.Müller, Heinsdorfergrund
Thorey Textilveredelung, Gera
AiF, Berlin