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THE
SOUTH AFRICAN PAINT INDUSTRY TRAINING INSTITUTE
SAPMA PAINT
TECHNOLOGY COURSE
MODULE 4 - PIGMENTS AND DISPERSION
In this Module the student studies the
function, manufacture, properties and testing of pigments, the principles
of dispersion, and the main types of dispersion equipment.
The study material comprises written text, divided
into 18 Lessons.
There are ten practical exercises in this Module,
and the student is expected to plan and implement these with minimum
guidance from the Counsellor. Wherever possible, use is made of
SABS or BS Standard Methods, and students are expected to evaluate
the method used, and to identify and discuss the critical parameters
of the test.
WHO SHOULD STUDY THIS MODULE
?
This Module is essential for those who are following
a technical career path, and in particular those in a laboratory
environment. In addition, those in the factory environment would
benefit from this Module.
PREREQUISITES FOR THE MODULE
Successful completion of Module 01 and Module 11 and
preferably some knowledge of organic chemistry.
A small portion of the syllabus involves an outline
of the chemistry of certain organic pigments. Thus, although prior
study of basic organic chemistry is desirable, it is not felt to
be mandatory.
SUMMARY OF SYLLABUS
A. REVISION OF BASICS
Hazards
Functions of pigments
B. COLOUR PRINCIPLES
Nature of colour
Illuminants
Spectra
The human eye and its perception of colour
C. COLOUR DESCRIPTION AND
MEASUREMENT
Visual colour matching
Munsell system
Additive and subtractive mixing
Additive and subtractive colorimeters
Spectrophotometer
CIE system
D. RHEOLOGY
Newtons Law of Viscosity
Non Newtonian behaviour
E. THE PRODUCTION OF PIGMENTS
Elements of the production process
Production of 2 inorganic and 2 organic pigments
Production of Titanium dioxide
Origin, composition and properties of common pigments
F. TESTING OF PIGMENTS
Description and comparison of different Standard Methods
Determination of:
- Tint strength
- Lightening power
- Contrast ratio
- Wet Hiding power
- Resistance to liquids
- Resistance to heat
- Resistance to bleeding
G. PIGMENTATION OF COATINGS
Pigment: binder ratio
Pigment volume concentration
Critical pigment volume concentration
Effect of pigment nature on coating properties
Determination of effect of PVC on gloss and opacity
H. PRINCIPLES OF DISPERSION
Basic principles
Wetting
Stabilisation
Mechanisms of dispersion
Letdown
Determination of Daniel flow point
I. DISPERSION EQUIPMENT
Construction, operation, formulation, hazards, advantages
and disadvantages of the main types of equipment.
J. DISPERSION PRACTICE
Efficiency
Economics
ASSESSMENTS
7 Multiple choice tests
10 Written reports on practical work
1 hour written exam midway through module
2 hour written exam at end of module
PASS MARK
A minimum of 50% in each of the three modes of assessment
is required for a pass.
A merit pass is awarded for an overall mark of 80%
or above, and a distinction is awarded for an overall mark of 90%
and above.
DURATION AND TIME INVOLVED
The Module takes 18 weeks to complete. The average
student would spend the following time on the various aspects:-
Theoretical study - 45 hours
Practical exercises - 15 hours
Report writing - 10 hours
This averages out to just under 4 hours per week
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