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Ana Ricardo

Especialista de Pintura de Aviões

TAP Manutenção & Engenharia

Pigmentos com Efeitos Especiais

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2003 – Celebrando 1 século de voo…

Desde…

… até.

Em 100 anos.

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Introdução

• História• Pigmentos com efeitos especiais• Critérios utilizados na avaliação de um efeito pigmento / cor particular• Exemplos

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História

Abr 1655

1917

1920

1940

1942

1970

1984

Presente

• Isolamento de substância brilhante prateada proveniente das escamas de peixe e início da produção industrial na Europa de lustrinas perladas

• Descoberta de que o efeito das lustrinas perladas é um fenómeno óptico, tendo por base a disposição horizontal de camadas finas, umas sobre as outras

• Primeira síntese da suspensão de lustrinas perladas

• Primeira produção de PbHPO4 em forma de plaquetas

• F.C. Atwood descreve a combinação de mica e TiO2 para o efeito das lustrinas perladas

• Produção de pigmentos de mica - TiO2

• Aplicação de pigmentos de óxidos metálicos para Revestimentos em OEM. Aceitação desta classe de pigmentos por todas as indústrias de pigmentos e de tintas.

• Todos os anos mais pigmentos com efeitos especiais, ficam disponíveis

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Pigmentos com efeitos especiais

• Tipos de pigmentos com efeitos especiais• Química destes pigmentos • Como avaliar uma cor• Critérios utilizados para avaliar um efeito cor / pigmento particular

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Tipos de pigmentos com efeitos especiais

Sólidos• revestimentos homogéneos (particles < 1 µm)

Effect pigments

• presença de flocos (partículas de > 5 µm)• 1ª classe / tipo (cintilante / efeito metálico)• 2ª classe / tipo (cores com interferência)

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Efeito dos pigmentos

• Efeito cintilante• Efeito interferente

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Effect pigments - types

Roughly categorised effect pigments:• Metallic pigments consist of very thin metallic flakes or wafers that

act as miniature mirrors. Their intensity changes according to the angle from which they are viewed. Maximum light intensity is achieved near the gloss, the angle at which the incident light is reflected. Minimum light intensity is experienced at an angle far away from the gloss.

• Mica flake effect pigments with single or multiple thin layers of metal oxide. The interplay of colours produced by these pigments is due to the layered structure of the metal oxide, which is also responsible for the rich deep glossy effect.

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Chemistry special effect pigmentMica

Cross-section through a silica flake coated with a-Fe2O3 (Hematite)

Electron micrograph of Al2O3 flakes

Mica – raw material

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SEM picture (top view) showing an Industrially produced iron oxide mica pigment

Transmission electron microscopic picture (TEM) showing a cross-section of an industrially produced iron oxide on α-Al2O3 substrate

SEM photo of a cross-section through an anatase/mica pigment particle. The anatase layers are precipitated to yield an average thickness of 140 nm on each side of the mica substrate for a blue interference colour

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Interference explained

d

glimmerplate

TiO2-layer

R2R1

reflection

I0

Lightα

normal

transmision

β

B

D

CA

2 2

2 2

δ n(AB BC) AD

δ 2d n s

d n

inα

λΔ 2 i αs n

2

= + −

= −

= − +

The resulting color depends on:• Layer thickness of the TiO2 • Refraction index• Angle of incidence of the light.

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Influence subject

1thin coat Several thin coats

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Influence of layer thickness

0

100

200

300

330nm 420nm 510nm 600nm 690nm

R [%]

golflengte λ

45° belichting/120° waarneming

9103

9205

9215

9235

9225

Increasing the layer thickness of TiO2 results in color shiftsTowards larger wavelengths.

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Influence of layer thickness

Branco prateado

Dourado InterferenteEncarnado Interferente

Azul Interferente

Verde Interferente

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Overview mica special effect colors

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Interference color

Sample 18: Chromaflair 230M M13

-80

-70

-60

-50

-40

-30

-20

-10

0

10

20

30

40

50

60

70

80

-80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80

a

b

40/-10

10/-10

20/-10 30/-10

60/-10

50/-10

45/-10

70/-10

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Perception special effect colors

Color is the perception which is formed in the brain of the observer via the eye, brought about by rays of light which are reflected or transmitted by homogeneous objects

Texture is the visible surface structure depending on the size and organization of small constituent parts of a material.

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How to evaluate a special effect color

• at large distance only color!• at microscopic level no match is required!

– orange pigment can be imitated by a combination of a red and yellow

5 m 5 cm 50 µm

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Evaluation color

Model defined in 1976 by CIECIE = Commission Internationale de l’Eclairage

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How to evaluate special effect color

• Classical: tilting simply simulates changes from a fixed light source and does not take any account of colour shifts produced through interference

• Modern: To allow interference shifts to be observed, the panel must be moved so as to allow the angle to the light source to be made steeper or flatter

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Criteria used for evaluation to a particular pigment / color effect

• Durability pigment– Chemical resistance– Light fastness

• Sprayability – uniform film• Reparability (spot repair)• Price• Weight

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Gulf Air – Selected Aviox Mica for whole fleet

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Germanwings- Mica success in maintenance

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Gulf Traveller- Mica success in maintenance

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Airbus Customer Aeroflot

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Airbus Customer- North West

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