Ultraviolet Protection of Knitwear Fabric

Ultraviolet Protection of Ultraviolet Protection of Knitwear FabricKnitwear Fabric

Ultraviolet Protection of Ultraviolet Protection of Knitwear FabricKnitwear Fabric

Polly Chiu, Jimmy LamPolly Chiu, Jimmy LamInstitute of Textiles & ClothingInstitute of Textiles & Clothing

The Hong Kong Polytechnic UniversityThe Hong Kong Polytechnic University

The 10th Asian Textile Conference, Sept 7-9 2009 Ueda, Japan

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Outlines• Introduction and Background• Experimental Details

– Six Reactive Dyes Group– Comparsion of different shade– Laundering– UV transmission test

• Results and Discussions– Effect of Colour– Effect of Shade

• Conclusions


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Introduction & Backgrounds

• Growing consumer demand for increased sun protection has driven the sun care market into innovative areas, including UV protective clothing.

• Such growth highlights the importance for consumers of protective aspects of clothing as opposed to fashion or utilitarian functions.

• UV protective clothing offers more durable protection against the harmful effects of the sun’s ray than sun screen.


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Introduction & Backgrounds(2)

• It is believed that the dominant reason for the occurrence of skin cancers is related to cumulative UVR exposure.

• Australia has the highest incidence of skin cancers in the world because Australia experiences some of the highest levels of solar ultraviolet radiation in the world.

• The reasons for the high levels of UVR include its geographical location, its close proximity to the equator, relatively clear atmospheric conditions, and most importantly, the influence of ozone depletion.


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Introduction & Backgrounds (3)

• The most common human cancer is thought to be the basal cell carcinoma (BCC), but it is arguable due to the well-recognized problem of under-registration of skin cancer.

• The incidence of MM is almost 100 times more common in Australia, and is approximately 30 times more common in the UK and US comparing to HK.

• In Australia, over one thousand people died from skin cancer annually and there are approximately 270,000 new cases of skin cancer diagnosed per year.

• While in Hong Kong, non-melanomaous skin cancer became one of the top 10 cancers in Hong Kong for the first time in 2002, and then it ranked as the 9th most common cancer in Hong Kong in 2006;


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HK UK USA Australia

Male/Female ratio 1: 0.71 1:1.14 1:0.64 1:0.65

Incidence rate* 0.5 13 16.2 46.9

Incidence relative to that of HK

1 26 32.4 93.8

Table 1: epidemiology of melanomas in different countries in 2003

The 10th Asian Textile Conference, Sept 7-9 2009 Ueda,

Japan

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Introduction and background

• The increasing incidence of skin cancers world-wide and the misconception of sun protection methods by the general public led to this research about how to provide UV protection by clothing, using chemical and textile engineering approach.

• It is believed that clothing, as a basic necessity, will be able to provide good solar UVR protection to human if the textile scientist chooses the correct parameters in engineering UV protective clothing.

• In this research, chemical approach of wet treatment has studied and their effect on blocking those harmful UV radiations on light-weight single jersey plain knitted fabric for summer outerwear were investigated.

• Initial findings showed that different dyestuffs, dye concentration and colour play an important role for UV protection on this knitted fabric

Experimental DetailsExperimental DetailsExperimental DetailsExperimental Details


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Experimental Details• Chemical approach was the first method to block the

harmful UV radiation to our skin. Dyeing was believed to be able to modify the proportion of UV light transmitted through fabrics and could increase UV protection performance. Dyes of different colors and color depths are important because of the following :

• 1) Fabrics with darker colors transmit less UV light than lighter colors;

• 2) Fabrics with darker shades of the same hue have higher UV protection ability.


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Six Reactive Dyes Group

• In this study, six reactive dyes of different colors and shades were used. They contained different chemical groups as follows:

• • Reactive dyes:• a) Remazol Brilliant Blue BB 133%;• b) Remazol Navy RGB ;• c) Remazol Red RB 133%;• d) Levafix Blue CA;• e) Levafix Royal Blue E-FR;• f) Levafix Navy CA.


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Figure 1: Dye curve for Remazol Dye Group


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Dyes shades and laundering

• Color appearance in terms of Hue was measured according to Hunter94 Model by the Macbeth CE-7000A spectrophotometer. Different shades were identified and compared later with results of UV test.

• Laundering is believed to cause changes in physical properties of fabrics and hence affecting UV blocking performance. Shrinkage of fabrics occurs after laundering which cotton fibers swell and close the small gaps between neighboring fibers, hence less UV light are able to pass through the fabric.

• In this study, steaming, a quick method to stimulate laundering was used by steaming with steam iron.


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UV transmission testCountry Australia/ New

ZealandUSA British & European

Standard number AS/NZS 4399:1996 AATCC 183:1998 BS 7914:1998Results expression All three standards report results as UPF ratingCalculation method Calculate mean UPF

value and average of UVA & UVB

transmission, to classify UPF level

Similar to AS/NZS 4399:1996

Calculate the erythemally effective

penetration (P): P=1/UPF

Testing condition Not specify any conditioning, normally 205C

and 5020% relative humidity

(RH)

Require sample conditioning of 211C and 652% RH for at least 4

hours

Require sample conditioning of

202C and 652% RH for at least 16

hours

Wavelength range 290-400nm 280-400nm 290-400nmSamples required 4 samples test

required6 samples test

required4 samples test

requiredSamples state Only specifies

testing in dry and relaxed state

Provide measurements of

wet and/or stretched samples

Provide measurements of wet and/or

stretched samples for European

standard (EN13758-1)

Results and Results and DiscussionsDiscussionsResults and Results and DiscussionsDiscussions


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Results and Discussions

Effect of Dyeing• Exhaust dyeing with reactive dyes of different chemical

structures was applied to the 100% cotton knitted fabric. The dyes used included: – VS type – Remazol Brilliant Blue BB 133%; – VS-VS type – Levafix Royal Blue E-FR and Remazol Navy RGB; – MFT-VS type – Levafix Blue CA;– MCT-VS type – Remazol Red RB 133%; and – TFP-VS type – Levafix Navy CA

• Fabrics were dyed in 5% concentration so a very dark shade was obtained. The dyes provided different shades of blue except one for a red color. Therefore, fabrics with different color shades and color were taken to the UV spectrophotometer where the mean UPF values were measured as shown in Table 2.


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Dye Applied Dye Type

Hue MeanUPF

Calculated UPF

UVA%T

UVB%T

Control 36Y64G 3.376 2.956 26.41 27.31

Remazol Brilliant Blue

BB 133%

VS 98B2R 897.19 871.985 0.18 0.1

Levafix Royal Blue E-FR

VS-VS 90B10R 219.511 215.724 0.51 0.31

Remazol Navy RGB

VS-VS 93B7R 998.805 998.408 0.1 0.1

Levafix Blue CA

MFT-VS 89B11R 999.805 998.665 0.1 0.1

Levafix Navy CA

TFP-VS 86B14R 977.97 957.145 0.12 0.1

Remazol Red RB 133%

MCT-VS 13B87R 975.805 935.657 0.12 0.1

Table 2:Results of dyeing on fabric UPF


Japan

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Effect of Dyeing• As shown in Table 2, the control sample has a low UV

protection and the mean UPF was 3.376, which could not be rated according to the Australia/New Zealand standard AS/NZS4399:1996. However, after treating this fabric by dyeing with reactive dyes,most of the fabrics showed a mean UPF of almost 1000.

• The reason for the effective UV protection by applying the dyes was that the colored dyes were able to absorb UV radiation in the part of dyes absorption spectrum which overlaps with the UV spectral region. Different chemical structure of the dyes led to various selective absorption of visible light or color, therefore different proportion of UV wavelengths were absorbed by the dye which decreased transmittance and increased UV protection.


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Effect of Dyeing

• Increased concentration of dye of same color on same fabric led to darker shade of fabric, which also increased the UPF.

• It is because more dyes were presented to absorb UV lights and thus lower transmission was achieved.

• In this experiment, 5% concentration was used and was a relatively high concentration that leads to the excellent protection from UV radiation.


Japan

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Effect of dyes on % Transmission

0.000

0.100

0.200

0.300

0.400

0.500

0.600

0.700

0.800

0.900

1.000

290

300

310

320

330

340

350

360

370

380

390

400

Wavelength (nm)

% T

rans

missio

n %T (A)%T (B)%T (C) %T (E)%T (G)%T (J)

Control sample

Figure 1: Effect of dyes on % transmission


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Effect of Shade• Hue is defined as the attribute of a visual sensation

according to which an area appears to be similar to one, or to proportions of two, of the perceived colors red, yellow, green and blue. Hue was measured according to Hunter94 Model and the 5 shades of blue were resulted in small difference.

• This led to similar results in the mean UPF, except for Levafix Royal Blue E-FR, which may cause by experimental error (as shown in Table 2). The red dye also showed similar UV protection capability since the hue number of red was similar to those of blue.

• Different color depths affect absorption and also the reflectivity of UV photons with dye molecules having a specific role. Thus it is believed that darker colors, such as dark navy blue and red used in this experiment, transmit less UV than lighter colors, such as oatmeal and white.


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• As shown in Figure 1, the control sample (B) showed a large UV transmission before dyeing (red colour with 0.8% transmission) with mean UPF of 3.37.

• The effect of dyeing significantly reduced the percentage of UV transmission. The curve A (Leavafix Royal Blue E) reduced the UV transmission to 0.6% with mean UPF to 219.

• All the other dyes (Curve J, E, C) significantly reduced the UV transmission to 0.2% with mean UPF of 998.

•

The 10th Asian Textile Conference, Sept 7-9 2009

Ueda, Japan

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Conclusions• Textile dyeing and finishing process has a

significant effect on reducing the harmful UV radiation on textile fabrics. This experiment shows that the open space structure of single jersey plain knitted cotton fabric (gauge 20) can be enhanced on UV protection by simple dyeing process.

• The mean UPF has been increased from undyed grey fabric of 3.37 to dyed Royal Blue fabric of 219 and to dyed Levafix Nacy CA fabric of 977.

• The dark colours like dark blue and red with higher concentration will result in greater UV protection of the fabric.

The 10th Asian Textile Conference, Sept 7-9 2009

Ueda, Japan

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Conclusions• However, it is also suggested that color or

color depth should be considered in combination with various properties known to modify UV transmission.

• For instance, during the process of dyeing, the increased UV protection may not only cause by the effect of dye, but may also due to the effect of shrinkage after wetting which caused a tighter and closer structure.

• Therefore, other properties like fabric structure, thickness, weight and tighter factor will be further investigated


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Acknowledgement• The authors would like to acknowledge

the funding supports from the Central Research Grant (A-AS21) from the Hong Kong Polytechnic University.

Documents

Ultraviolet Protection of Knitwear Fabric