light stability testing of home and personal care products

Light Stability Testing of Home & Personal Care Products

Light Stability Testing of Home and Personal Care Products

Jeffrey Quill Director of Technical Applications

Q-Lab Corporation

Cleveland,Ohio Headquarters & Instrument Division

Bolton, England Q-Lab Europe

Q-Lab Corporation • Founded in 1956 • Specialize in material durability testing equipment and

services

Shanghai, China Q-Lab China

Saarbrücken Germany

Presenter

Presentation Notes

Q-Lab was founded in 1956. We specialize in material durability testing equipment and services. Our headquarters and manufacturing are located in Cleveland, Ohio, and we have sales and support facilities in Bolton, England, Saarbrucken, Germany, and Shanghai, China.

Phoenix, Arizona Miami, Florida

Cleveland, Ohio

Q-Lab Outdoor Weathering Sites

Presenter

Presentation Notes

Our outdoor testing services include the largest Florida site in the industry and another near Phoenix, Arizona. In addition we have a small exposure field at our headquarters in Cleveland.


Topics 1

• Weathering Testing vs. Light Stability • Sunlight • Interior Lighting • Natural Exposures • Xenon Arc Testing

– Daylight and Window Spectra – Irradiance Control – Temperature & RH Control


Topics 2

• Fluorescent UV & Cool White Testing

• Testing Best Practices & Practical Considerations


Forces of Weathering

Sunlight

Temperature

Moisture

Presenter

Presentation Notes

Weathering looks at the combined and often synergistic effects of sunlight, temperature, and moisture.


Weathering Testing

• Simulation of sunlight—direct or through window glass

• Moisture (water spray) usually included • Temperatures simulate realistic hot

outdoor conditions

Presenter

Presentation Notes

Light induced degradation is often affected by temperature and moisture, so these are part of weathering tests.


Light Stability

Sunlight

Artificial Light

Presenter

Presentation Notes

Light stability testing is a subset of weathering testing. Generally it is looking strictly at the effects of light exposure on materials without concern for the effects of temperature or moisture.


Light Stability Testing

• Simulation of sunlight or indoor lighting • No moisture • May have RH control • Test temperatures often simulate typical

indoor environment

Presenter

Presentation Notes

Light stability testing is a subset of weathering testing because it de-emphasizes the roles of heat and moisture. Tests are often performed at room temperature and without moisture or relative humidity control. Test chambers designed to perform weathering tests generally have greater capabilities than chambers designed strictly for light stability tests.


Definitions Irradiance: The rate at which light energy falls on a

surface, per unit area; usually given as W/m2 Spectral Power Distribution (SPD): Graph of

irradiance vs. wavelength Radiant Dosage: Irradiance x Time; accumulated

light energy exposure per unit area over a period of time

Presenter

Presentation Notes

Let’s give a few basic definitions before getting started. You’ll be hearing the terms irradiance and SPD quite a bit.

Sunlight

Sunlight

• Direct • Filtered through

window glass

Presenter

Presentation Notes

The most important element of weathering is sunlight, so let’s talk about it.


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Sunlight--Direct and Through Window Glass

Direct Sunlight

Sunlight throughWindow Glass

Presenter

Presentation Notes

This is the first of several Spectral power distributions you will see….(explain what an SPD is) This data shows direct sunlight versus sunlight through window glass. We will show additional data for different definitions of window glass later.


Direct Sunlight

Noon Summer Sunlight/Air Mass 1 – ASTM G177 – CIE 85 Table 4 – D65 (CIE & ISO)

Air Mass 1.5 – ASTM G173 – IEC 60904-3

Presenter

Presentation Notes

There are many standards for sunlight spectra. For weathering or light stability tests, starting with noon summer sunlight as the definition makes sense because it is a realistic condition and the most intense sunlight materials are going to experience at the Earth’s surface.


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Standard Sunlight Spectral Power Distributions

CIE 85 Table 4SMARTS2 ASTM G177

Presenter

Presentation Notes

The black line represents CIE 85 Table 4, the most widely accepted definition of noon summer sunlight. The green one is a newer standard that differs mainly in the resolution of the data. We use it in weathering and light stability testing because we sometimes needs the extra resolution it provides.


Summer Sunlight Spectrum

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Visible Light

UVA

UVB

U

VC

Presenter

Presentation Notes

The sunlight spectrum is often divided into a few key components. Here we see that summer sunlight contains UVB and UVA radiation as well as visible light. If we extended the graph further to the right, we would see the infrared portion of the spectrum.


Even Though It Is Only 5% of Sunlight...

UV Causes Most Photodegradation

Presenter

Presentation Notes

Know your enemy


Wavelength Regions of UV UV - C

100 – 280 nm

Found in outer space

UV – B

280 – 315 nm

Includes shortest wavelengths at earth’s surface: severe polymer damage; absorbed by window glass

UV – A

315 – 400 nm

Causes polymer damage

Presenter

Presentation Notes

When we focus in on the UV portion of the spectrum, we see that the shortest wavelengths, UVC, are not found on the earth’s surface. We do receive UVB energy, which causes severe polymer degradation. It is completely absorbed by standard window glass. The earth receives a lot of UVA energy, which is defined between wavelengths of 315 and 400 nm. It also causes polymer degradation and may or may not be filtered by glass, depending on the type of glass. Organic compound Coating Sealants Adhesives


Sunlight Spectrum – UV Region

Presenter

Presentation Notes

The sunlight spectrum is often divided into a few key components. Here we see that summer sunlight contains UVB and UVA radiation as well as visible light. If we extended the graph further to the right, we would see the infrared portion of the spectrum.


Sunlight through Window Glass

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CIE 85 Table 4

CIE 85 Table 4, 3 mm Glass

CIE ID65 6 mm glass

Presenter

Presentation Notes

The gray line represents that CIE 85 table you saw earlier. The other two represent common definitions of sunlight through window glass. Now, we all know there are many types of window glass. The two blue data lines show sunlight through window glass of two thicknesses. The light blue one represents a reference in the ICH Guidelines, which we will discuss later.


Sunlight Through Window Glass

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Direct Sunlight CIE 85 Table 4

CIE ID65 6 mm glass

Direct Sunlight CIE 85 Table 4

CIE 85 Table 4, 3 mm glass

CIE ID65 6 mm glass

Presenter

Presentation Notes

When you zoom in on the UV part of the spectrum, you can see how window glass filters the shortest wavelengths. The thicker the glass, the more the cut-on wavelength is shifted to the right. In general, this filtering effect is why you don’t get a sunburn from sunlight through a closed window.


Interior Lighting


Commercial Indoor Lighting

Presenter

Presentation Notes

This graph shows several common indoor lighting types: cool white fluorescent, high pressure sodium, and metal halide. LED lighting is not shown here. However, any indoor light source is going to produce light in the same spectral region. LEDs tend to have narrow peaks at high intensity, but this is dependent on how the different colored LEDs are packaged together to create white light. Because of the variety of lighting types and the wavelengths of light energy received, testing in a xenon arc chamber is a good way to ensure light stability to the gamut of indoor lighting types in use.


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Typical Indoor Lighting (4x normal illuminance) vs Xenon, QUV, Sunlight

QUV with cool white lamps 20 klx (40x typical office)

Sunlight through Window Glass

QUV with UVA-351

Q-SUN with Window-Q

4x Typical Indoor Light Level

Presenter

Presentation Notes

Indoor light levels barely show up on this graph. We had to increase it by 4x just we can see it. This clearly shows that noon summer sunlight and irradiance levels in the QUV and Q-SUN are 40-100x higher than typical indoor lighting.


Average Home Lighting

Presenter

Presentation Notes

The last chart shows relative intensity of the light sources we have been talking about. This one shows, in rough terms, how well the spectra of xenon, cool white fluorescent, and typical indoor lighting conditions match each other. This is from a study done by Kodak to characterize typical home lighting conditions. The histograms compare spectra of the home lighting environment (light yellow), window glass filtered xenon (purple) and cool white fluorescent lamps (blue). Neither is perfect, but the window glass filtered xenon was a better match than the cool white spectrum.


Natural Exposures

Presenter

Presentation Notes

On the left you can see beverage bottles on outdoor exposure at one of our outdoor test sites. Colorants and flavorings were being evaluated.


Natural Exposures

• Benchmark Commercial Sites – South Florida – Arizona Desert – Inexpensive – Reliable – Extreme environments create acceleration – “Scientific Window Sill Testing” – Convenient

Presenter

Presentation Notes

We encourage customers to setup outdoor exposure areas at their own facilities—we sell outdoor weathering racks to help them. However, there are benefits to having a professional, dedicated site for outdoor exposures. We won’t lose track of your tests. More importantly, we run outdoor sites in global benchmark locations: South Florida and Arizona. These sites are what we call reasonable worst case scenarios, meaning many markets exist in climates similar to these. In addition, they provide acceleration compared to most global market environments.


Florida Site

Latitude 25° 27’ North

Elevation 8 feet

Annual Solar Energy:

TUV 280 MJ/m2

Total 6,588 MJ/m2

%Sun 69%

Under Glass 193 MJ/m2

5,416 MJ/m2

Summertime Average Max Air Temp:

32°C

90°F

Presenter

Presentation Notes

Review Slides Point out 280 MJ Annual Solar Energy as “Standard Florida Year” Note the Under Glass data. The TUV data is estimated, but the total radiant dosage under glass is measured.


Arizona Site

Latitude 33° 23’ North

Elevation 1055 feet

Annual Solar Energy:

TUV 334 MJ/m2

Total 8,004 MJ/m2

%Sun 85%

Under Glass 230 MJ/m2

6,563 MJ/m2

Summertime Average Max Air Temp:

40°C

105°F

Presenter

Presentation Notes

Review Slide Point out 334 MJ as “Standard Year” in Arizona, 20% greater than FL While we don’t directly measure under glass exposures, these are reasonable estimates.


DIY Natural Exposures

Presenter

Presentation Notes

Photo of the “Sun-box” in Mexico.


Xenon Arc


Q-Sun Xenon Test Chamber


Optical Filters

Daylight Filters (exterior exposures)

Window Glass (indoor exposures, textiles, inks, etc.)

Extended UV

(automotive, aerospace, etc.)


Light Spectrum

• Critical Factor • UV “cut-on” or “cut-off” • Not all “Window” or “Daylight” filters are

the same • Commercial filter names create confusion


Xenon with Daylight Filters

Presenter

Presentation Notes

Three daylight filters are represented on this chart. All three are controlled to 0.68 W/m2 at 340 nm. As you can see, there are differences between them. The Daylight F filter is more transmissive in the UV region. Since it requires less power to the xenon lamp to produce 0.68 W/m2 at 340 nm, it has lower irradiance in the UV region. It was designed by the automotive coatings industry because of its close match to sunlight in the UV region.


Daylight Filters – UV Region

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Daylight - F

Direct Sunlight

Daylight - Q

Daylight - B/B

Presenter

Presentation Notes

If you need to make inter-laboratory comparisons, these slight spectral differences can reduce correlation, so make sure you choose filters carefully.


Xenon with Window Filters vs. CIE85 through 3mm Glass

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Window-Q

Window-B/SL

Window-IR


Xenon with Window Filters vs. CIE85 through 3mm Glass

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Window-Q

Window-B/SL

Window-IR

Presenter

Presentation Notes

Change tags to match line colors


Xenon with Window Filters vs. ID65 (6mm glass)

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Window-IR

Window-SF5

CIE ID65 6 mm glass


Xenon with Window Filters vs. ID65 (6mm glass)

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Window-IR

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CIE ID65 6 mm glass


Irradiance Control

• Narrow Band – 340 nm – 420 nm

• Total UV (300-400 nm) Wide Band • Global (300-800 nm) – not recommended

– Shorter wavelengths cause more photodegradation

– Fails to account for xenon lamp aging

Presenter

Presentation Notes

Over the next few slides, we’ll show you why we don’t recommend global irradiance control.


Narrow Band Control

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Q-Sun Window - Q

Sunlight thru glass

340 nm Control

420 nm Control

Sensor detects single wavelength and maintains constant irradiance at that

wavelength


Wide Band Control -- TUV

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Q-Sun Window - Q

Sunlight thru glass

Sensor detects energy

from 300 to 400 nm and maintains constant

irradiance


Global Control (300-800 nm)

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Q-Sun Window - Q

Sunlight thru glass

Sensor detects energy from 300 to 800 nm and

maintains constant global irradiance


Irradiance Control Points Example: Window B/SL Filter

These represent the same intensity: Control Point Irradiance

340 nm 0.35 W/m2

420 nm 0.95 W/m2

TUV (300-400 nm) 43 W/m2

Global (300-800 nm) 442 W/m2

Presenter

Presentation Notes

Try to find an SPD of a REALLY old lamp.


Temperature Control • Black panel

– Hotter than ambient in sunlight – Not necessarily same as specimen temperature – Exists for test repeatability and reproducibility

• Chamber air – Controlled somewhat independently – More relevant for some applications

• Chiller System – Removes heat to allow normal indoor temperatures

inside xenon arc test chamber


Black Panel Temperature

Insulated Black Panel Black Standard

Black Panel (uninsulated)

Two types of black panels!


QUV Fluorescent UV Weathering Tester and Cool White Light Stability Tester


QUV Specimen Holders


QUV Spectra vs. ASTM G177 Sunlight

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ASTM G177 Sunlight

QUV with Cool White, 20 kLux

QUV with UVA-340

QUV with UVA-351

Presenter

Presentation Notes

Add comment CW spd that this is 40x typical indoor lighting irradiance


UVA-340 Lamps

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Sunlight (ASTM G177)

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Cool White Lamps

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QUV/cw Spectral PowerDistribution


Best Practices for Light Stability Testing

1. Perform natural exposures – Necessary for understanding accelerated

results – Does lab test correctly rank material

performance? Miami



2. Test until failure (forced degradation) – Required for drug products

• Identify impurities resulting from photodegradation • Determine degradation pathways

– Necessary for developing rank order performance



3. Expose a control with your test specimen • Use Control Material of Known Durability

– Outdoor performance – Lab performance

• Similar Composition to Test Material • Similar Degradation Mode to Test Material

Presenter

Presentation Notes

Similar chemistry is critical (need to compare nylon to nylon, urethane to urethane, alkyd to urethane - not fair comparison) Control and new material must have same degradation mode (cracking to cracking, not cracking to gloss)


Benefits of a Control

• Compare performance of control to a known material

• Allows confidence in lab exposure • Assure that lab tester is operating

properly

Presenter

Presentation Notes


Example: Correlation using Control Material

• Background – New products must

be lightfast – Ingredients to make

it lightfast are expensive

Presenter

Presentation Notes

Every new Flavor must be tested for lightfastness. Light fastness ingredient was the most expensive. Gatorade Mex. had to send all formulations to NY (time and they knew first)


Correlation with Control Material • Selected a control

product • Included control with

all new product testing

• Test 36 hours • If new product fails,

add lightfastness ingredients

• Retest

Presenter

Presentation Notes

They selected a flavor / color as a light fastness control (secret) New Formulations were put in Q-Sun next to the control for 36 hours. The control just starts to change in this time but has not failed. If new formula fails, they add more lightfast ingredient and retest They can now produce new flavors much quicker


Best Practices for Light Stability Testing 4. Test your product “In the package” in order to simulate the actual service environment.

Presenter

Presentation Notes

There are some practical considerations when testing whole products, which we will discuss in a moment.

Conclusions

• Understand and define the service environment

• Define what constitutes product failure • Obtain real world results • Define evaluation method and understand the

variability • Test both constituent parts, finished product

and product in packaging


Questions?

light stability testing of home and personal care products

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