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THE 11TH ASIAN TEXTILE CONFERENCE
Influences of Knitted Fabric Construction
& Color on Ultraviolet Protection
Presenter: Wong Wai Yin
Dr. Jimmy Lam, Dr. C.W. Kan
EXCO, Daegu, KoreaNov 1-4, 2011
2
OVERVIEW
Introduction
Literature Review
Background
Previous Findings
Experimental Details
Results & Discussions
Conclusion
Future Study
References
3
INTRODUCTION Increasing no. of people dying from skin cancer due to over exposure to UVR
Skin ageing, skin cancer, cataract, ↓ Effectiveness of immune system
Excessive sun exposure in childhood is likely to contribute to skin cancer in later life
Clothing provide limited protection against UV radiation
Factors affecting UV protection of clothing:
Fiber Composition
Fabric Construction: tighter structure, smaller the fabric pores for UVR transmission
Yarn twist
Fabric Thickness, Weight
End-use conditions: Wetness / Stretching
Coloration: absorption band of dye extend into invisible UV region (290-400nm)
Chemical Treatments / Additives
UVA UVR in the range of 315-400 nm
UVB UVR in the range of 280-315 nm
UVC UVR in the range of 100-280 nm(mostly absorbed by ozone layer)
4
LITERATURE REVIEW
Parameters affecting UV protection are well researched
Many studies have concentrated on:
Woven fabrics
Chemical approaches to enhance UV protection
UV absorbers: TiO2, ZnO, optical brightening agents
Little work has been done on:
Influence of knitted fabric construction
Structural parameters of knitted fabric against UVR transmission
UV protection provided by stretched or wetted knitted fabrics
5
BACKGROUND
Aim: Improve UV protection of summer knitwear
by modifying the fabric construction
Chemical Approach by using UV absorbers (ZnO,TiO2):
Problem of fiber & dye degradation by photo-catalytic mechanism
Challenges on wash-fastness & adhesion to fabrics
Pollution, water consumption of those chemical treatments
Engineering Approach by modifying fabric construction
Environmental friendly manufacturing process
Especially suitable for knitwear (more elastic and creates more open spaces
when stretched)
UV protection enhanced by chemicals is only sufficient when fabric structure
is closed enough
6
PREVIOUS FINDINGS
Fabric construction with different types of stitches possess distinct UV protection ability
UV protection factor of greige & bleached cotton fabrics with: Miss stitch > Knit stitch > Tuck stitch Double Knitted fabrics > Single Knitted fabrics
7
EXPERIMENTAL DETAILS
MachineGauge Length
Materials usedSingle Knitted Fabric
constructions
Stoll CMS 82214G Computer Flat Knitting Machine
14G100% Cotton
40s x 3 (42 Tex)
1. All Knit (Plain)2. Knit & Tuck3. Knit & Miss 25%4. Knit & Miss 50%
Notation:Single Knit Structures
1. Fabric Specimens Production:
8
EXPERIMENTAL DETAILS
Greige Fabrics produced in gauge length 14G
Scouring & Bleaching
Dyeing with reactive dyes
Red
0.1%
1%
3%
Yellow
0.1%
1%
3%
Blue
0.1%
1%
3%
Black
0.1%
1%
3%
2. Coloration with Reactive Dyes:
Reactive dyes with bi-functional group for better color fastness
Temperature rise process 25-60℃ L.R. = 50:1 Four shades:
Red: Levafix Red CA (MFT-TEP) Yellow: Remazol Yellow 3RS (MCT-VS) Blue: Levafix Navy Blue E-BNA (FCP-VS) Black: Remazol Black A (VS-DCT)
Three level of depths:
0.1%, 1%, 3%
9
MEASUREMENTS OF UPF
Ultraviolet Protection Factor (UPF) indicates how much UVR is blocked by a textile
materials (e.g. UPF 20 allows 1/20th of UVR passing through fabric)
Measured by Cary 300 Conc UV-Vis spectrophotometer with a schott UG 11 filter in a
dry, flat and tensionless state (un-stretched)
Australian/New Zealand Standard (AS/NZS 4399:1996)
In Vitro Method: Transmittance (T%) of UV spectrum (290-400 nm) through fabric
and calculating the ratio of erthemally weighted solar UVR irradiance measured by a
detector with and without fabric sample in place
UV protective clothing should have a minimum UPF 15
↑ UPF ≈ ↓ Transmittance
10
MEASUREMENTS OF COLOR YIELD (K/S SUM)
Measured by a Macbeth Color Eye 7000A spectrophotometer
Acquired at CIE standard observer 10° viewing angle
Under CIE standard illuminant D65 (daylight illumination)
Specimens were folded into layers to ensure opacity but without stretching
K/S Sum value is calculated by summation of each K/S value within the
visible spectrum (400-700 nm) with 10 nm intervals:
↑ K/S ≈ ↑ Concentration of colorant in the medium
11
RESULTS & DISCUSSIONS
K/S
S
um
K/S
S
um
No major difference in color yield (K/S sum) whereas distinct difference in UPF among
various knit structures in red & yellow colored fabrics
Knit & Miss structures have higher UPF than All Knit and Knit & Tuck structures
↑ UPF ~ ↑ dye concentration (color depth)
Although darker colored fabric provides superior UV protection, thermal comfort is a concern
especially for summer wear.
Darker shaded clothes absorb more infra-red radiation causing wearer feels hot
12
RESULTS & DISCUSSIONS
K/S
S
um
K/S
S
um
No major difference in color yield (K/S sum) whereas distinct difference in UPF among
various knit structures in red & yellow colored fabrics
Color is not a reliable indicator for UV protective performance of fabrics
UV protection depends on dye’s absorption characteristics in UV region which further
controlled by their specific structural attributes rather than the chemical class of the dye
(Srinivasan et al., 2000)
13
CONCLUSION
For colored cotton fabrics with the 4 single knit structures:
Knit structures have significant influence in UPF but not for Color yield (K/S
sum)
Knit & Miss structure provides better UV protection in all the 4 colors than
the All Knit and Knit & Tuck structures
↑ UPF ~ ↑ dye concentration (color depth)
Darker shaded clothing may not be suitable for summer wear
∵ higher absorption of IR radiation, feel hotter
To achieve thermo-physiological comfort, fabrics with Knit & Miss
structure are recommended for lighter shaded clothing
14
FUTURE WORKS
With various knit constructions: Influence of stretching and wetting on UV
protection of knitwear with various knit constructions
Effect of fiber type Yarn structures e.g. bulkiness & hairiness Impact of laundering and abrasion affect UPF of
various knit structures
15
REFERENCES Ultraviolet radiation and human health (2009). Retrieved May 10, 2011 from
http://www.who.int/mediacentre/factsheets/fs305/en/index.html Skin Cancer Facts (2010). Retrieved June 20, 2011 from
http://www.cancer.org/Cancer/CancerCauses/SunandUVExposure/skin-cancer-facts J. Fan, & L. Hunter, Engineering Apparel Fabrics and Garment, Cambridge: Woodhead:
Textile Institute; Roca Raton, Fla.: CRC, 309-338, (2009). The American Society for Testing and Materials, ASTM D1776-04, Standard Practice
for Conditioning and Testing Textiles. Australian/New Zealand Standard, AS/NZS 4399:1996, Sun protection clothing –
Evaluation and classification. M. Srinivasan and B.M. Gatewood, Textile Chemist and Colorist & American Dyestuff
Reporter, 32(4), 36-43, (2000). P.D. Dubrovski and D.Golob, Textile Research Journal, 79(4), 351-359, (2009).
The research is funded in part by the General Research Fund (A-SA21) from the University Grants Committee, Hong Kong and The Hong Kong Polytechnic University, Hong Kong.
ACKNOWLEDGEMENT
THANK YOU!