Invisible but functional - ir coatings

transcript

12 mai 2023

Invisible but FunctionalIR-reflective coatingsSmart Coating Application Lab

2 mai 2023 2© sirris | www.sirris.be | info@sirris.be |

It all starts with the sun…Electromagnetic radiation

5% UV (300-450nm) Skin damage Degradation of paint and

polymers 46% VIS (450-750 nm)

Colors our world 49% (N-)IR (750-2500 nm)

Mostly heat

Source: heubachcolor

Heat: Absorption of VIS and IR radiationDegradation of

Colors (mostly due to UV) Gloss Elasticity

Thermal expansion, stressAir conditioning

increase of energy consumption

Mechanisms of heating

What do you need to keep (it) cool?

High solar reflectance Ability to reflect sunlight

High thermal emittance Ability to radiate heat (ease of

loosing heat to the environment)

Quantification of heat buildup

TSR (Total Solar Reflectance) (in %)Def: TSR is the percentage of irradiated energy that is reflected by an object High TSR = high reflection = lower heat buildup

IR reflective pigments Provide means to get the TSR as high as possible

without color changes

TSR is influenced by pigmentation

Source: BASF

What are IR-reflective pigments?

Organic based Inorganic based Ceramic (MMO* and CICP**)

Moderate durable Long term durability Unparalleled resistance to heat, light chemicals,

Low cost Higher cost High cost

<molted metals, high temp

*Mixed Metal Oxides, **Complex inorganic colored pigments

Conventional pigments IR reflecitive pigments

What makes the pigments IR-reflective? Most important for NIR reflectivity

Mean particle size Nanoparticles significantly enhance reflective properties

The particle size should be more than half the wavelength of the light to be reflectedReflecting IR in the range of 800-1200 nm you needs

pigment particle sizes of at least 400 to 600 nm

Source: http://rhopoint.co.kr/bbs/board.php?bo_table=rho_faq&wr_id=4

For example: IR black pigment

Source: BASF

TSR black:42%

Comparison between regular and IR pigment

Source: BASF

Other important parameters Colour of the substrate/using white primer

TSR over white substrate is higherPigment IR brown

Source: CPSColor

Other important parameters Thickness of the coating

Thicker coating gives higher TSR: needs optimalisation

Source: CPSColor

Other important parameters

High enough concentration of the IR pigment Contamination

Small amounts of non IR reflecting colorants can have drastic effects

Source: CPSColor

Other important parameters

Binder system

Source: CPSColor

Panels used for outdoor application Exposure to direct sunlight resulted

in deformation of the panels IR reflective paints were used to

investigate the use of IR-reflective pigments on the surface temperature

IR reflective paint on PVC panels

SetupIR reflective paint on PVC panels

Measurementspigment TSR 150µ Temperatur

eBlack 35,4 107°CIR Black 54,12 72°C

Temperature reduction of 35°C

Conclusions

Keeping it cool is possible with heat reflective paints, regardless the colors used.

The system needs optimalisation to ensure maximum TSR

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Invisible but functional - ir coatings

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