Coloring of Plastics Presented by:. Created July 2007 Last Modification 5 September 2007. Coloring of Plastics. Color and Color Science. Colorants – Pigments and Dyes. Inorganic - Organic Pigment Particles. Definitions. Color Appearance. Color. Hue. Color Attribute Identification.
Created July 2007
Last Modification 5 September 2007
The three elements of color vision
Rod shaped receptors in the eye are responsible for night vision
Cone shaped receptors are responsible for our daylight vision and color reception
Red,Green, and Blue are the three types of cone shaped receptors
Experiments quantified the response functions of the human eye.
Observers viewed a white screen through an aperture subtending 2o FOV.
Half the screen was illuminated by a test light. The other half illuminated by observer-controlled, adjustable lights (primaries).
The observer adjusted the intensity of the three primary lights until the color of the test light matched.
This process was carried out over the entire visible gamut.
Tristimulus Response Functions
In 1931 it was believed that color vision was confined to the fovea region ~2o. Later it was determined that this is NOT true and the experiment was repeated in 1964.
The result being the Supplemental Observer, called the 10o Supplemental Observer!
The 10o Supplemental Observer function givers better correlation with visual observations and assessments.
Most commercial applications should use this function.
2o & 10o Observer Functions
Objects & Spectral Reflectance
Spectral Reflectance Curve
Light interacts with an object
Light, (zeta), will be;
Reflected, R or
Mathematically we express this as:
= A + R + T
Hence the total amount of light incident upon a sample is equal to the sum of the amounts absorbed, reflected, and transmitted.
The magnitude of A, R, or T depends on the object – is it transparent, translucent, opaquesmooth, or rough? (etc).
PP, HDPE, LDPE
Nylon, PET, PBT, ASA, PC
LARGE PARTICLE SIZEOPAQUELOWER SURFACE AREAHIGH HEAT STABILITYEXCELLENT LIGHTFASTNESSVARYING WEATHERABILITYLIMITED TINT STRENGTH (EXCLUDING TiO2)
WIDE VARIETY OF SHAPES
Pigment TypeExamples Manufacturing
Metallurgical deposition processes
CdS, CaCO3, ZnS,
Purification of natural
Minerals, High temperature
Solid state reactions
Mixed Metal Oxides,
SMALL PARTICLE SIZETRANSPARENTLARGER SURFACE AREAVARYING HEAT STABILITYVARYING LIGHTFASTNESSVARYING WEATHERABILITYHIGH TINT STRENGTHLARGE SELECTION OF COLORANTSBRIGHT CLEAN COLORS
Insoluble metal salts of acid dyes
Basic Dyestuff Complexes
Modified Titanium Dioxide
Multi Layered Inorganics
Edge Glow, Fluorescent
DESIGNED FOR PLASTICS
INORGANIC ORGANIC DYES
HIGH HEAT (300 C) + - -
COLOR STRENGTH - + +
LARGE PARTICLE SIZE + - -
TRANSPARENT - +/- +
WEATHERABILITY + +/- +/-
ONE ALWAYS NEEDS TO CHECK EACH COLORANT PROPERTIES BEFORE USE
Dry Pigment Least Expensive Dispersion can be inconsistent and cleanup extensive
0.2% Pigment with 2% TiO2 in PVC, Daylight in Northern Europe
PARTICLE SURFACE AREA
PIGMENT VOLUME CONCENTRATION
PIGMENT AVERAGE PARTICLE SIZE
PIGMENT PARTICLE DISTRIBUTION
PIGMENT PARTICLE SHAPE
PIGMENT SURFACE TREATMENTS
POTENTIAL PIGMENT PARTIAL SOLUBILITY
PIGMENT SOLUBLE SALTS
COMPLEX SYSTEM REFRACTIVE INDEX
pH OF ALL SYSTEM COMPONENTS
SYSTEM VISCOSITY OR FLOW
SYSTEM MELT TEMPERATURE
SUSEPTABLITY TO SHEAR
DILATANCY (THICKENS WHEN SHEARED)
THIXOTROPY (THINS WHEN SHEARED)
POTENTIAL PIGMENT REACTIVITYGENERAL COLORANTSPROPERTIES AND/OR PARAMETERS
UNEFFECTED LIGHT RAY
SCATTERED LIGHT RAYS
REFRACTED LIGHT RAY
PIGMENT PARTICLE SIZE HAS A DIRECT EFFECT ON PIGMENT EFFECTIVENESS. TOO SMALL A ND LIGHT RAYS ARE UNEFFECTED. LARGE PARTICLES WILL REFRACT LIGHT, BUT NOT SCATTER IT. PARTICLES WITH DIAMETERS ABOUT HALF THE WAVELENGTH OF THE LIGHT GIVE MAXIMUM SCATTERING
TYPICAL ASPECT RATIOS FOR PARTICLE SHAPES
4 - 30
1 - 4
80 - 200
ASPECT RATIO DEFINITION
The Aspect Ratio is defined as the ratio of the longest length of a particle
to the thickness of that particle.
Aspect Ratio = Longest Particle Dimension / Thickness Dimension
POOR DISTRIBUTIVE MIXING GOOD
POOR DISPERSION COMPLETE
SMALL INORGANIC PIGMENT = 0.05 MICRONS
SMALL ORGANIC PIGMENT = 0.01 MICRONS
SMALL NANO-PARTICLE = 0.0003 MICRONS
FALLING OBJECTS 712
FARM MACHINES 553
BATHTUB FALLS 345
FALLING COCONUTS 150
DRUG SIDE EFFECTS 156
FALLS INTO HOLES 99
HIT BY LIGHTNING 80
SNAKE BITES 68
FAULTY APPLIANCES 66
SERIAL KILLERS 20
HEAVY METALS ± 1
Source: National Safety Council
ACCIDENT STATISTICS IN 1992 FOR THE UNITED STATES CAUSES DEATHS CAUSES DEATHS
The information in this presentation is furnished in good faith based on current technology, experience, experience, and knowledge thought to be true. The Color and Appearance Division (CAD) of the Society of Plastics Engineers (SPE) makes no warranty or assumes no responsibility of any kind, expressed or implied, regarding this information. CAD and/or the SPE does not assume any responsibility for any subsequent processing or compounding of any resources or materials in order to produce compound(s) or any finished article(s). Nor does CAD or SPE imply this information may suggest any legally binding assurance of certain properties or suitability for any specific purpose. It is the responsibility of those using this information to ensure their actions complies with any proprietary rights and/or existing laws or legislation.
Colorants – Pigments and Dyes
Steve Goldstein, Ph D
Inorganic - Organic Pigment Particles
Color and Color Science