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Paints Industry: Raw materials & unit operations & Equipment &
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Thesis · August 2019
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PAINTS INDUSTRY
Raw Materials & Unit Operations & Equipment
& Manufacturing & Quality Tests
AbdAl-Rhman Magdy Abdullah Youssef
Departments of Engineering
Departmnet of Chemical Engineering
Higher Technological Institute-10Th of Ramadan City
PAINTS INDUSTRY
Raw Materials & Unit Operations & Equipment &
Manufacturing & Quality Tests
Student: AbdAl-Rhman Magdy Abdullah Youssef
ID: 20160517
Examiner Committee
Prof. Mostafa Hamdy Azab
Assc.Prof. Soad Awad
Professor of chemical enginnering
Assc.Professor of organic chemistry
Higher Technological Institute – 10Th of Ramadan City
Higher Technological Institute – 10Th of Ramadan City
Eng. Al-shimaa Hafez
Assistant Teacher
Higher Technological Institute – 10Th of Ramadan City
August 2019
Abstract
Increasing student skills in the field work, and linking
theory with application, become the motivation to students to
join to factories and companies for achieving this target. One of
chemical process industries is the paints industry. Paints is a
main part of coatings, paints composed of five components
which are; resin (binder), solvent, filler, pigments, and
additives.
From the point of view of chemical engineering; paints
manufacturing, requires number of unit operation which are
mixing, milling, and filtration. These of operations done using
several industrial units which are; mixers, mills, and screen
filters.
Paints manufacturing done by adding binders, solvents,
and thickeners to provide a gel phase which its existence is a
mark for starting of adding fillers and pigment, through and
after manufacturing processes a samples send to laboratory to
done some tests, by which the manufacturer be sure from his
products quality, the main tests are density, viscosity, and
hiding power test, there several tests can be done also such as
wash-ability and impact test .
i
Acknowledgement
The first one who deserve my thanking is Allah for his reconcile
and attention for me, I can’t achieve thanking for all his great
graces.
I’m entirely grateful to ISIPAC team who give me from there
wide knowledge and their time.
deep gratitude must go to my parents who supported me in my
life and give me the useful advices which make pass through
life tests, also I specially thank my grandfather and my
grandmother for their support.
ii
Dedication
To the man who his ideas, be a reason for our success
My grandfather\ Youssef Mohamed Aly Kaseb
1916-1998
iii
Contents
Abstract………………………………………………………………………….i
Acknowledgement……………………………………………………………...ii
Dedication……………………………………………………………………..iii
Contents………………………………………………………………………..iv
List of Figures………………………………………………………………..viii
List of Tables…………………………………………………………………..ix
List of Abbreviations…………………………………………………………...x
Chapter One: Introduction……………………………………………………...1
1.1: Student mission for training activity…………..……………………1
1.2: Historical background……………………..………………………..1
1.3: Paints products……………………………………………………...1
1.3.1: Epoxy paints………………………………………………..1
1.3.2: Polyurethane paints………………………………………...1
1.3.3: TV & Phones Paints………………..………………………2
1.3.4: Aluminum Paints………………….……………………….2
1.3.5: Primers……………..………………………………………2
1.3.6: Varnish……………..………………………………………2
1.4: Paints curing………………………………………………………...2
1.5: Paints application…………………………………………………...2
Chapter Two: Paints Raw Materials……………………………………………3
2.1: Introduction…………………………………………………………3
2.2: Resin………………………………………………………………...3
2.2.1: Epoxy resins………………………………………………..3
iv
2.2.2: Polyurethane resins………………………………………...4
2.2.3: Acrylics…………………………………………………….5
2.2.4: Amino resins……………………………………………….6
2.2.5: Alkyds……………………………………………………...6
2.3: Solvents……………………………………………………………..7
2.3.1: classification of solvents…………………………………...7
2.4: Filler……………………………………………………………….10
2.5: Pigment ……………………………………………………………10
2.6: Additives…………………………………………………………..11
Chapter Three: Paints Unit Operations & Equipment……...…………………12
3.1: Introduction………………………………………………………..12
3.2: Mixing operation…………………………………………………..12
3.2.1: Liquid - liquid Mixing……………………………………12
3.2.2: Solid- liquid mixing………………………………………12
3.3: Mixing Equipment…………………………………………………13
3.3.1: Impeller design……………………………………………13
3.3.2: Vessel flow pattern………………………………………..14
3.4: Milling operation…………………………………………………..15
3.5: Milling equipment…………………………………………………15
3.5.1: Mill Design………………………………...…………….16
3.5.1.1: Rotary mill………………………………………16
3.5.1.2: Ball Mill………………………………………….16
3.6: Filtration operation………………………………………………...17
3.7: Filtration equipment……………………………………………….17
v
Chapter Four: Paints Products Manufacturing………………………………..18
4.1: Introduction………………………………………………………..18
4.2: paints manufacturing Procedures………………………………….18
4.3: Epoxy paints……………………………………………………….19
4.3.1: Manufacturing o epoxy 2k system procedures…………...19
4.4: Aluminum paint……………………………………………………20
4.5: Primer……………………………………………………………...21
4.7: Lake………………………………………………………………..21
4.6: Poly urethane (2 components)……………………………………..22
4.7: varnish……………………………………………………………..23
4.8: Thinners……………………………………………………………24
Chapter Five: Testing paints…………………………………………………..25
5.1: Introduction………………………………………………………..25
5.2: laboratories mission………………………………………………..25
5.3: Raw material checking…………………………………………….25
5.3.1: Solvent test………………………………………………..25
5.3.2: Pigment test……………………………………………….26
5.4: Final Products tests………………………………………………...26
5.4.1: Viscosity test……………………………………………..27
5.4.2: Density test………………………………………………..28
5.4.3: fineness test……………………………………………….28
5.4.4: Hiding power……………………………………………..28
5.4.5: Gloss Test…………………………………………………29
5.4.6: Acid value………………………………………………...30
vi
5.4.7: Adhesion force……………………………………………30
5.4.8: Storing effect……………………………………………...30
5.4.9: Drying rate…………………………………………………30
5.4.10: Wash-ability test………………………………………….31
5.4.11: Impact Resistance test…………………………………….31
Chapter Six: Conclusions………………………………………………………32
References……………………………………………………………………...33
vii
List of Figures
Chapter Two
Figure (2.1): Classification of solvents according to principle of working……….8
Figure (2.2): classification of solvents according to chemical structure………….9
Chapter Three
Figure (3.1): A mixing unit……………………………………………………..13
Figure (3.2): Representative impellers for fluid mixing in mechanically agitated
vessels…………………………………………………………………………..14
Figure (3.3): Vessel flow patterns………………………………………………15
Figure (3.4): Rotary mill………………………………………………………..16
Figure (3.5): Horizontal ball mill……………………………………………….17
Figure (3.6): Basket-ball mill…………………………………………………...17
Figure (3.7): Screen filter ………………………………………………………18
Chapter Four
Figure (4.1): Paints manufacturing flow sheet………………………………….19
Chapter Five
Figure (5.1): cup used in measuring density……………………………………26
Figure (5.2): Measuring viscosity by using cup 4 device………………………..27
Figure (5.3): Measuring viscosity with visco-meter…………………………….27
Figure (5.4): Measuring fineness with hegman device………………………….28
Figure (5.5): different shapes of pulling tools…………………………………..29
Figure (5.6): Pulled film………………………………………………………...29
Figure (5.7): measuring of hiding power by opacity meter …………………….29
Figure (5.8): Measuring of gloss degree using gloss meter …………………….30
Figure (5.9): Wash-ability testing device……………………………………….31
Figure (5.10): Measuring impact resistance from a hight 60 cm………………...31
viii
List of Tables
Chapter Two
Table (2.1): Alkyds lengths and its properties…………….….………7
Table (2.2): Color and its pigments………………..………...………10
Table (2.3): Paints Additives………………………………………...11
Chapter Four
Table (4.1): epoxy-base components………………………………..19
Table (4.2): epoxy-hardener components……………………………19
Table (4.3): Aluminum paint components…………………..............20
Table (4.4): Aluminum pastel contents……………………………...21
Table (4.5): Primer components…………………………………......21
Table (4.7): Polyurethane-base components………………………...23
Table (4.8): Polyurethane-hardener components……………………23
Table (4.9): Varnish components……...………………………….....23
Table (4.10): Paints and its thinners……………………………..…..24
ix
List of Abbreviations
QCL: Quality control laboratory
MEK: methyl ethyl ketone
2K: 2 component system
x
Chapter One
Introduction
1.1: Student mission for training activity
The training mission is linking theory with application which improve
several chemical engineering fields which is paints by knowing its production’s
processes and industrial units, also knowing its several applications which give
some experience for working in this field after graduating.
1.2: Historical background
The surface-coating industry is indeed an ancient one, the origin of paints
dates back to prehistoric times when the inhabitants of the earth recorded some of
their activities in colors on the walls of their caves. These crude paints consisted
probably of colored earths or clays suspended in water. The Egyptians, starting
very early, developed the art of painting and by 1500 B.C. had a wide number and
variety of colors.
Around 1000 D.C. they discovered the forerunner of our present-day varnishes,
using naturally occurring resins or beeswax for their film forming ingredient.
Pliny outlined the manufacture of white lead from lead and vinegar, and it is
probable that this ancient procedure resembles the old Dutch process. It is in more
recent years, however, that the surface-coating industry has made its greatest
strides owing to the results of scientific research and application of modern
engineering, [1].
1.3: Paints products
Paints has a several products, each of it has a purpose for manufacturing it
but the two main purposes are protection and decoration. Protective paints is more
important than decorative paints, In following sections sum of protective paints
are described in some details.
1.3.1: Epoxy paints
Most of epoxy paints are working as two-component system (2K), and used
for several applications most of it for coating; concrete, steel structure, and
wooden grounds as primer and finish also coating metal surfaces such as; petrol
pipes and tanks. One of important coating missions is coating pipes and tanks for
water and oil.
1.3.2: Polyurethane paints
As epoxy its work depend usually on the 2K system with high wash-ability
weathering and chemicals resistance, which make it suitable for applying steel,
wooden, and concrete surfaces.
1
1.3.3: TV & Phones Paints
It's thermoplastic acrylic finishing coat with high adhesion and weathering,
water and aliphatic hydrocarbons resistance, which make it suitable for air
spraying for TV and phones.
1.3.4: Aluminum Paints
It’s a metallic paint used in protection purposes, it depends on aluminum
paste as pigment, which give it corrosion resistance.
1.3.5: Primers
It can be manufactured from alkyds, or resins such as epoxy, it used for
covering surface pores, and leveling surface to be painted with other type of paints
such as lake.
1.3.6: Varnish
It’s a color less paint used for protection, and disappearing the primed
surface under it.
1.4: Paints curing
Curing is the process of converting the applied wet paint to a dry film. The
paint may cure by solvent loss (lacquers and emulsions), chemical reaction
(enamels), oxidation (oil base house paints), melting and re-solidifying, or
melting and crosslinking (powder coatings). Energy is usually required for
dependable and consistent drying of industrial coatings.
Air-dry paints rely on solvent evaporation into the surrounding atmosphere. The
temperature and humidity will have a profound impact on the drying time. Low
temperature and/or high humidity will not provide sufficient atmospheric heat to
rapidly dry the paint. Ovens or dehumidification equipment can be used to speed
up the drying time and make it more predictable, [2].
1.5: Paints application
There are four main methods of applying paint:
1-by spreading, e.g. by brush, roller, paint pad, or doctor blade;
2-by spraying, e.g. air-fed spray, airless spray, hot spray, and electrostatic spray;
3-by flow coating, e.g. dipping, curtain coating, roller coating, and reverse roller
coating;
4-by electrodeposition, [3].
2
Chapter Two
Paints Raw Materials
2.1: Introduction
Once seeing a painted wall or paint package, the first conception is it’s a
colored liquid but this wrong, several ingredients used to manufacture this colored
liquid some of this components are solids such as resin, pigment, additives and
the one liquid component that dissolve all of these mentioned solids is the solvent
that obtain the paint in a liquid state in the following sections each component
will be described in some details.
2.2: Resin
It’s the component that identify the paint, several resins are used in paints
manufacturing, it works as binder for collecting all paint components, the mixture
of solvent and resin usually called “vehicle”. The binder (Resin) classified into
two classifications; the first classification is convertible binders which non fully
polymerized but it partially polymerized and it complete its polymerization during
film formation when painting. An example of convertible binders is polyurethane,
epoxy, and thermosetting acrylics.
The second classification is the non-convertible resins that is fully polymerized
such as nitro cellulose and cellulose but this type not common in uses like the first
one, [2].
2.2.1: Epoxy resins
It’s a resin produced by step wise polymerization, which obtained in
equation (2.1), with starting with a condensation reaction between
epichlorohydrin and dihydric alcohol such as phenol, and bis-phenol A, in alkaline
medium. Epoxy resins traded under names such as; araldite, and epon, [7], by
several suppliers such as; Dow plastics, Epic resins, Resyn corp., Shell chemicals,
and united resin corp, [4].
2.2.1.1: Properties of epoxy resins
Epoxy resins have good several properties vary from the high tensile,
excellent chemical and corrosion resistance, very law shrinkage, good electrical
insulation, also it can be cured over wide range of temperatures, to its high
adhesion force to several substrates such as metals which give it high importance
in coating industry, [5].
3
Equation (2.1), [6]
2.2.1.2: Curing of epoxy resins
As mentioned, epoxy resins can be cured in wide temperatures depending
on the used curing agent, several curing agents such as; aliphatic amines aromatic
amines, catalytic curing agent, and acid anhydride. For using epoxy in coating
industry, the curing agents that used are aliphatic amines, and catalytic curing
agent.
Curing epoxy with aliphatic amines such as (DETA) occurs at room
temperature, but curing at this low temperature has its disadvantages which
performed in the relatively short working life and limited mass in curing process
to avoid crazing, cracking, or charring of resin system. Also giving the cured
resins with this system gives it high tendency toward degradation at high temp.
For more development and improvement another curing agent is used which is
catalytic curing agent (BDMA), which cure epoxy resins at 100◦C, which make it
avoid the disadvantages of curing with aliphatic amine such as limited curing
mass, [4].
2.2.2: Polyurethane resins
Urethane or carbamates is the term that used to describe products of stepgrowth polymerization, of di-isocyanate and polyol, that polyurethane classified
4
according to it. It can be provided in both classification of thermo setting and
thermo plast, dependent on aliphatic and aromatic segments in polyurethane
structure, [4].
Equation (2.2), [4]
2.2.2.1: Polyurethane properties
As mentioned, polyurethane classified according to polyol used its
manufacturing which has its effect on properties of PU, but it generally remarked
with its; abrasion resistance, flexibility, toughness, chemical resistance, weather
resistance, [4].
2.2.2.2: Polyurethane curing
Polyurethane can be cured with different systems such as curing of
polyurethane with MF in automotive primers, also systems of based solvent and
based water, also moisture curing system.
2.2.3: Acrylics
The term acrylic has come to represent those polymers containing acrylate
and methacrylate esters in their structure along with certain other vinyl
unsaturated compounds. Both thermoplastic and thermosetting systems are
possible, the latter formulated to include monomers possessing additional
functional groups that can further react to give crosslinks following the formation
of the initial polymer structure, [3].
2.2.3.1: Acrylics properties
The properties of acrylics depend on its type according to it thermo plastic
or thermo setting. Thermo plastic has resistance for water and chemicals also
resistance for fumes, and it has resistance to UV degradation. Thermo setting has
lower molecular weight, hence higher solids at application viscosity, usually
formulated on cheaper solvents, better gloss and general appearance (after baking)
improved chemical, solvent, acid and alkali resistance.
5
2.2.3.2: Acrylics Curing
Curing of acrylic paints or emulsion paints based on physical process which
is water vaporization, no other solvent used so paints that depend on acrylics
considered as environmental paints as it doesn’t pollute environment.
2.2.4: Amino resins
Amino resins are generally used in baked coatings as cross-linking agents.
They are used in proportions up to 50% of the total vehicle binder. They can be
used with alkyds, polyesters, epoxies, thermosetting acrylics, phenolics, and other
heat reactive resins, [2].
2.2.5: Alkyds
It’s a thermosetting resin produced from reaction of organic alcohol and
organic acid, which both of them are selected carefully to meet the required
specifications, and then can be modified with oils. Also, it can be prepared directly
from reaction of organic acid, organic alcohol, and oil (Tri-glyceride).
Equation (2.3), [7]
In the past alkyds be prepared depending on polyester, but now it prepared
depending on variable resins.
2.2.5.1: Alkyds properties
The oils that used in modification alkyd resins such as coconut, dehydrated
castor, or soya. The selection of oil and its percentage classify the end use
properties such as speed of drying, flexibility, and durability. Alkyds has three
types depending on oil length, its properties obtained in table (2.1)
6
Table (2.1): Alkyds lengths and its properties, [2]
Alkyd
Oil length%
Properties
Short
20-25%
Non-oxidative, soluble in aromatic hydrocarbon
solvents, it gives a hard film
Medium
45-60%
Oxidative (Air drying), soluble in aliphatic or aromatic
solvent, it gives more flexible films
Long
60-80%
Air-drying (oxidative), soluble in
aliphatic solvents, it gives very flexible film
2.2.5.2: Alkyds curing
Curing of alkyds paints occurs chemically by oxidation reactions.
2.3: Solvents
It’s the second component of vehicle beside resins the first one, it’s function
to give flowability to the paint to make easy applying, and dissolving the resin
and other paint components. The important principle in solvents working is “Like
dissolves like”, solvent selection be according to several factors such as its
suitability to formula of paint, cost, and safety.
The second important factor in solvent working is the evaporation rate, some of
solvents can work as retards to slow the drying rate to give an open time for film
drying, but it required from solvent to have a good evaporation rate for speeding
paint layers applying.
2.3.1: classification of solvents
Solvents has many types according to its working principle, figure (2.1) showed
the different types of solvents according to principle of work, also it can be
classified according to its chemical structure which showed in figure (2.2).
7
Figure (2.1): Classification of solvents according to principle of working
8
Figure (2.2): classification of solvents according to chemical structure
9
2.4: Filler
Fillers is considered as additives but adding it with high quantities in paint
formula, forcing to consider it as a main component of paint formula, it has several
types can perform a co-work as fillers and others such as; retardants for flame like
alumina tri hydrate (ATH). The most common are calcium carbonate, talc, silica,
wollastonite, clay, calcium sulfate, mica, glass structures, and ATH. Fillers serve
a number of purposes such as reducing cost.
2.5: Pigment
Pigments are particulate solids that are dispersed in paints to provide certain
characteristics to them, including color, opacity, durability, mechanical strength,
and corrosion protection for metallic substrates. Pigments classified into organic
pigments; which used in decoration paints, and in-organic pigments; which are
metallic pigments, used in protective paints
Table (2.2): Color and its pigments, [3]
Color
White
Inorganic pigment
Organic pigment
Titanium dioxide
Zinc oxide
Zinc sulphide
Antimony oxide
Black
Carbon black
Black iron oxide
Aniline black
Iron oxides brown
Benzimidazolone
Lead chromate
Yellow iron oxide
Arylamide
Diarylide
Cadmium red
Red iron oxide
Metallized Azo Reds
Perylene
Ferric potassium ferrocyanide
Cobalt blue
Copper Phthalocyanine Blue
Chrome green
Chromium oxide
Hydrated chromium oxide
Copper Phthalocyanine Green
Brown
Yellow
Red
Blue
Green
10
2.6: Additives
Although its low percentage in paints composition, it has high effect in
improving properties, through this low percentage paints manufacturer
distinguished, several additives used in paints formula such as thickeners, dryers,
anti-skinning, defoamers, etc.
Table (2.3): Paints Additives
Additive
Principle of work
Examples
Anti-Settling
agents
Preventing of settling of paints solid content
such as; pigment and filler during storing.
• BYK Anti-Terra 203,
• Crayvallac,
• polyolefins.
Anti-skinning
agents
Anti-sagging
agents
Anti-foaming
agents
Preventing of skin formation on surface of
autoxidative air-drying paints in storing.
Increasing viscosity which provide sagging.
•
•
•
Methyl ethyl ketoxime,
cyclohexanone oxime.
Polyolefins.
lowering the surface tension in the
neighborhood of the bubble, causing them
to coalesce to larger, less stable bubbles
which then break
Protection is achieved in two stages; The
UV absorber (about 1%) converts the
undesirable short wavelengths to heat
energy, and the light-stabilizer captures the
free radicals generated that would cause
film degradation.
It works by oxidation of cationic metal from
a stable lower valency to a less stable higher
valency, this will speed oxidization
reactions
This creates a reversible three-dimensional
network which increases the viscosity.
Formation of chemical bonds with the
substrate surface and the binder; or
•
•
•
BYK 023,
BYK03,
Pyrenol.
•
•
•
Tinuvin 1130 UV
absorber,
Tinuvin 1123 HALS,
Tinuvin 1144 HALS.
•
Co, Ca, and Mg octoate.
•
Benton (Activated &
non-activated)
silanes,
silicones,
titanium compounds,
amides,
Light
stabilizers
Dryers
Thickeners
Adhesion
promoter
increasing in the wettability of the surface; or
formation of an interlayer between substrate
and binder.
11
•
•
•
•
Chapter Three
Paints Unit Operations & Equipment
3.1: Introduction
Manufacturing paints depend mainly on three physical processes which are
mixing, milling, and filtration, which will be described in some details, and
according that 3 industrial units used which are mixers, mills, filters, each of them
will discussed in some details.
3.2: Mixing operation
In paints manufacturing several ingredients used to formulate paint system,
each of them has properties differ from others which mean that there is no
homogeneity between all these several components, mixing process has a vital
role in achieving homogeneity to the mentioned components to get the final paint
system. All paints components are in solid or in liquid state so the used mixing
techniques, will be depends on; solid - liquid mixing, and liquid – liquid mixing.
3.2.1: Liquid - liquid Mixing
Most of paints components are liquids for providing a final liquid state for
paint applying, three processes occur simultaneously to achieve homogeneity
which are; coalescence, dispersion, and suspension.
Coalescence and Dispersion; occur dependence on shear or velocity
gradient which resulted from mixing speed of liquids drops, which force drops to
deform, to daughter drops increasing due to high energies that produced by
dispersion, after deformation they disperse, collide with each other, and then
coalesce.
Suspension; occur depending on flow movement inside mixing vessel,
which come from speed of mixing, so high-speed mixers are used to achieve
coalesce drops suspension, [8].
3.2.2: Solid- liquid mixing
Solid content of paint system varies, and may reaching to 50% or more
from contents of paint formula, and usually added in the middle stages of mixing
after adding some liquidous components. This mentioned solid content is a finite
powder, dissolved in other liquidous components by three processes which are;
suspension, distribution, and drawing down of solids by agitation.
12
Suspension; the condition where no particle remains on the bottom of the vessel
(or upper surface of the liquid) for longer than 1-2 sec. this position achieved by
existence of anti-settling agents and high rotating speed.
Distribution; it means that there’s no particles in flocculated state usually in
bottom of mixing vessel, this achieves by using dispersing agents which led for
particles distribution in all directions inside vessel.
Drawing down of solids; it achieved by agitation, and represented in mixing by a
cone shape around agitator, [8].
3.3: Mixing Equipment
As obtained in figure(3.1) mixing operation in paints industry requires a
jacketed vessel for water cooling or for steam heating, which is usually vertical,
and high-speed mixer consists of one or more impellers, which consisted of a shaft
contain one or more disk mixing blade, it driven by electrical motor and its
rotational speed organized using inverter.
Figure (3.1): A mixing unit
3.3.1: Impeller design
Impeller can be classified to axial, radial, and helical, according to shape of
disk that attached to impeller shaft, usually helical used in mixing pastes that has
high density and viscosity, while axial and radial used in mixing paints that has
low density and viscosity, figure (3.2) show the different types of impellers.
13
3.3.2: Vessel flow pattern
There are four flow patterns for vessels which obtained in figure (3.3), but
according to require to achieve con shape or vortex for solid-liquid mixing, the
first flow pattern will be used.
Figure (3.2): Representative impellers for fluid mixing in mechanically agitated vessels. (a) The
three-bladed Marine Propeller, (b) Chemineer HE-3 hydrofoil, (C) the Rushton turbine, (d) 4blade 45° pitched blade, (e) 4-blade flat blade, (F) concave blade, (g) sawtooth, (h) helical
ribbon, (I) Anchor, (j) Ekato intermig, (k) hollow-shaft,(l) paravisc, [9].
14
Figure (3.3): Vessel flow patterns. (a) Axial or radial impellers without baffles produce
vortexes. (b) Off center location reduces the vortex. (c) Axial impeller with baffles. (d) Radial
impeller with baffles, [9].
3.4: Milling operation
If the mixer power does not achieve the required fineness for the mixture,
the needing for milling appear to achieve the required fineness, the problem which
leads for using mills is that there’s a still colloid particle not dispersed in the
mixture although existence enough amount of dispersing agent.
The point of view in this process is damaging these agglomerations of particles
and dispersing it in the mixture, and this can be done by several processes, most
common one in paint industry is collision the agglomerated particles with small
balls, these small balls manufactured from several materials such as glass, steel,
and ceramics. Ceramics and glass for medium and light paints, and steel for dark
paints, the amount of balls put be according to the following equations;
Amount of balls=Capacity of tank * Density of ball * Percentage of balls………equation (3.1)
3.5: Milling equipment
There are two types of mills used in paints industry; rotary mills, and ball
mills. Ball mills is more suitable and provide more safety than rotary mills
because milling processes done in open-air state which is non-suitable wit paints
that contain volatile solvents, these emissions are harm for working team, but in
case of ball mills it done under circular cover which prevent solvent emissions.
15
3.5.1: Mill Design
The used mills in paints industry is rotary mills and ball mills, and as
mentioned previously using ball mills is better than rotary mill.
3.5.1.1: Rotary mill
It consists of number if rollers each of them rotates in opposite direction
from the other one, as obtained in figure (3.4), and with different speed, between
each two rollers there’s a clearance controlled to get the required fineness.
Figure (3.4): Rotary mill
3.5.1.2: Ball Mill
This type of mills uses small balls that crashed with colloid particles, it has
two types classified according to its position the first one is horizontal type and
the other one is vertical type.
Horizontal ball mill; as obtained in figure (3.5), it consists of cylindrical tube and
inside its horizontal axis and disks fixed on it rotate around its center each impeller
contains holes for moving of paint, this machine can use both of steel or glass or
ceramics balls.
Figure (3.5): Horizontal ball mill
16
Vertical ball mill; it also called with basket mill this type has more efficiency than
the horizontal type, also it only uses ceramic balls which give his its efficiency,
figure (3.6) show the basket-ball mill.
Figure (3.6): Basket-ball mill
3.6: Filtration operation
A rest colloid particles and ability of glass balls to be broken in case of
using it, so the filtration operation needed, several techniques can be used in paints
filtration but, screening filtration is more common in paints industry.
3.7: Filtration equipment
As mentioned, the screen filter which obtained in figure (3.7), is the most widely
filter, simply it consists of sheet of cross-linked steel with holes for purification
of paint.
Figure (3.7): Screen filter
17
Chapter Four
Paints Products Manufacturing
4.1: Introduction
From the ancient time of discovering paints, its making depend on
blending, the first paint not have the required durability, the modern technology
and discovering new resins, make humans be able to manufacture new paints have
high adhesion force, durability, and other specific properties as they need, in this
chapter the stages of manufacturing of paints be discussed, beside manufacturing
of some products.
4.2: Paints manufacturing Procedures
Firstly, surface active agents, usually thickeners added to give a gel stage
after that binders or oils added, in addition to adding pigment and fillers also
amount of solvent added, this procedure called premixing, after that a sample sent
to laboratory to get a report about its fineness, viscosity, and density.
If the fineness not meet the required specifications, the mixture charged to the
milling unit, after that the other additives and the rest amount of solvent added
and mixed in a procedure called thinning, after this procedure another sample sent
to the laboratory to done some tests such as, viscosity, density, and hiding power.
If test results meet the required specification, the quality lab. Give a permission
to start packaging, and before that the final mixture purified using a bar screen,
after that it packaged manually, semi-automatic, or automatic according
production volume, figure (4.1) show the flow sheet of paints manufacturing.
Figure (4.1): Paints manufacturing flow sheet, [10]
18
4.3: Epoxy paints
Epoxy systems are considered from the best systems of paints specially and
of coatings generally, most of it using in protection purposes, it has several
systems, but the common system is the 2-component system, an example of 2K
system components is obtained in table (4.1), and the hardener in table (4.2).
Table (4.1): epoxy-base components
Component
Vehicle (Solvent +Resin)
Epoxy resin with solid content
100%
Epoxy resin with solid content
75%
Hydrocarbon resin dissolved in
xylene
Iso butanol
Xylene
Pigment
Titanium di-oxide
Carbon black
Additives
Nonyl phenol
BYK 163
Silica flower
Barium sulphate
Crayvallac
Based silicones
Phase
Function
Liquid
Binder
Liquid
Binder
Liquid
Binder
Liquid
Liquid
Solvent
Solvent
Solid (powder)
Solid (powder)
Pigment
Pigment
Liquid
Liquid
Solid (Powder)
Solid (Powder)
Liquid
Liquid
Wetting agent
Dispersing agent
Filler
Filler
Thickener
Anti-foaming agent
Table (4.2): epoxy-hardener components
Component
Phase
Function
Iso butanol
Xylene
Polyamide
Ankamide
Liquid
Liquid
Liquid
Liquid
Solvent
Solvent
Hardener
Accelerator
4.3.1: Manufacturing o epoxy 2k system procedures
At first the mixing unit must be cleaned well, with toluene or any solvent,
to remove the rest of the previous batch, after that we use another small mixing
unit for mixing the amount of hydrocarbon resin in a same amount of xylene, we
can use another solvent but for saving time xylene is used, this procedure take
usually 30 minutes. After that the 2 epoxy resins added in the main mixing unit,
in addition to xylene, nonyl phenol, and iso-butanol, and start of mixing
19
components for 30-45 minutes until the mixture temp. reach 50-60◦C, which is the
suitable for Crayvallac to start its work as thickener and anti-settling agent, when
reaching to the required mixing temperature, the other components of epoxy base
added; Crayvallac, fillers, TiO2, and carbon black to get a grey color.
This mixture mixed for 30 minutes for dissolving these added powders after
adding BYK 163, which is a dispersion agent. After that a sample sent to quality
control laboratory (QCL) to test its fineness, and with QCL acceptation the
defoamer added, and mixed, after that another sample sent to QCL to test its,
viscosity, density, and hiding power.
The hardener manufactured by injection all its components, which obtained
in table (4.2), in another tank and mixed for 15-20 minutes, and sending a sample
for QCL, and after acceptation the product filtrated using a screen filter, packaged,
and labeled.
4.4: Aluminum paint
It’s a protective paint used for metallic constructions it has a simple formula
which showed in table (4.3), manufactured by adding xylene, propylene glycol
mono ether, and aqualon which work as a thickener. These components mixed for
20 minutes, after that aluminum pastels which its composition showed in table
(4.4), added and mixed with the previous added components for 10 minutes, after
that the silicon resin and butyl titanate added and mixed very well with mixture.
A sample sent to QCL and tested, after that the mixture milled, filtrated, and
packaged.
Table (4.3): Aluminum paint components
Component
Phase
Function
Liquid
Liquid
Liquid
Binder
Solvent
Solvent
Aluminum
Solid (Paste)
Metallic pigment
Aqualon
Butyl Titanate
Liquid
Liquid
Thickener
Anti-moisture agent
Vehicle (Resin + Solvent)
Silicone resin
Xylene
Propylene glycol mono-ether
Pigment
Additives
20
Table (4.4): Aluminum pastel contents
Substance name
Percentage (%)
Aluminum
Hydrocarbons (C9-C12), n-alkanes, iso-alkanes, cylices, Aromatic
(2-25%)
Fatty acid (C16-C18)
64-67
32-35
<1
4.5: Primer
Primer paints used for preparing surface to be painted, as it covers all
surface pores, leveling the surface to painted with a finish painting, its formula
showed in table (4.5), the first procedure is dissolving the hydro carbon resin in
white spirit, and this procedure take usually 2hours, during this mixing we use
another mixing unit for the other procedures.
The long alkyd resin, benton, and methanol added and mixed for 15-20
minutes, after that filler, and the pigment added and mixed for 20-30 minutes. A
sample sent to QCL for testing fineness, and after that dryers, anti-skinning agent,
and dissolved hydrocarbon resin added, and mixed for 10-15 minutes. Another
sample sent to QCL, to get a final report about its meeting to the specific
requirements, after that it milled, filtrated, and packaged.
Table (4.5): Primer components
Component
Vehicle (Resin + Solvent)
Long Alkyd resin (70%)
White spirit
Hydrocarbon resin dissolved
in white spirit
Pigment
Bayferox yellow
Additives
Benton 34-non activated
Methanol
Calcium carbonate
Methyl ethyl ketoxime
Zr, Co, Ca octoate
Phase
Function
Liquid
Liquid
Liquid
Binder
Solvent
Binder
Solid (Powder)
Green pigment
Liquid
Liquid
Solid (Powder)
Liquid
liquid
Thickener
Activation of Benton34
Filler
Anti-Skin
Dryers
4.7: Lake
Lake is used after primer painting, it has a formula usually contain alkyds
as a binder, table (4.6) show components of semi-gloss lake. The first procedure
in its manufacturing is adding the long alkyd resin, white spirit, soya lecisin,
benton 34, methanol, and half amount of TX. After adding this mixture mixed for
21
20 minutes to activate benton 34. After that filler and titanium di-oxide added and
mixed for 30 minutes.
A sample sent to QCL to get a report about its fineness, if the fineness
achieved meet the required specifications, dryers, toner, the rest amount of TX,
and anti-skinning agent added and mixed for 10-15 minutes. After that a sample
sent to QCL to get a report about its viscosity, density, and hiding power, also
done some other tests to ensure that it meet the required specification. After that
it filtrated and packaged.
Table (4.6): Semi-gloss lake components
Component
Vehicle (Solvent +Resin)
Alkyd resin 60%
White spirit
TX (Toluene-Xylene)
Pigment
Titanium di-oxide
Additives
Benton 34
Methanol
Soya lecisin
Methyl ethyl ketoxime
Zr, Co, Ca octoate
CaCO3
Toner
Phase
Function
Liquid
Liquid
Liquid
Binder
Solvent
Solvent
Solid (Powder)
White pigment
Liquid
Liquid
Liquid
Liquid
Liquid
Solid (Powder)
Liquid
Thickener
Activation of Benton 34
Dispersing agent
Anti-skinning agent
Dryers
Filler
Giving a shiny color
4.6: Poly urethane (2 components)
Approximately, it’s similar to epoxy in its using, and in its systems, the
most common system is 2K system, which for manufacturing it, a two mixing
units used, the first one used for manufacturing base and the other one, used in
manufacturing hardener.
In base manufacturing; which it components showed in table (4.7), toluene
de-isocyanate, xylene, crayvallac, and BYK 163 added and mixed until the
temperature of mixture reached to 55-60◦C, after that talk, barium sulphate, and
titanium de-oxide added and mixed well for 20-30 minute, a sample sent to
laboratory, to test its fineness, and after that the rest of additives added which are;
BYK 300, tinuvin 292, BYK 066, and cylan 187, and mixed for 10-15 minute,
after that a sample sent to QCL for tests, after that it filtrated, an packaged. In
hardener, which its components showed in table (4.8), it manufactured by adding
all of it components, in a vessel and mixing it for 10-15 minutes, after that it tested,
filtrated and packaged.
22
Table (4.7): Polyurethane-base components
Component
Vehicle (Solvent +Resin)
toluene de-isocyanate
Xylene
Pigment
Titanium di-oxide
Additives
Crayvallac
Tinuvin 292
Cylan 187
Talk
Barium sulphate
BYK 163
BYK 300
BYK 066
Phase
Function
Liquid
Liquid
Binder
Solvent
Solid (Powder)
White pigment
Solid (Powder)
Liquid
Liquid
Solid (Powder)
Solid (Powder)
Liquid
Liquid
Liquid
Thickener
Light stabilizer
Adhesion promoter
Filler
Filler
Anti-settling agent
Surface
Anti-foaming agent
Table (4.8): Polyurethane-hardener components
Component
Phase
Function
Xylene
Polyamine
Liquid
Liquid
Solvent
Hardener
4.7: Varnish
It used for cover surface, but it has a distinguished property, which that it’s
not contains a pigment in its formula, which mean it’s a colorless paint, simply it
manufactured by adding the short alkyd resin, nitro cellulose and the mentioned
solvent in table(4.9), and mixing them for 10-15minute, after that adding zinc
strate, and talk, and mixing them for 10-15 minute. After that it filtrated, and
packaged.
Table (4.9): varnish components
Component
Vehicle (Solvent +Resin)
Short alkyd resin
Nitro-cellulose
Turpentine
Ethyl glycol
Butyl acetate
Additives
Zinc strate
Talk
Phase
Function
Liquid
Liquid
Liquid
Liquid
Liquid
Binder
Binder
Solvent
Solvent
Solvent
Solid (Powder)
Solid (Powder)
Defoamer
Filler
23
4.8: Thinners
It’s a solvents composition, used for thinning paints products, with defined
percentages defined by the manufacturer, methanol is used as a filler, to decrease
cost of thinner, table (4.10) show types of paints and its thinner solvents.
Table (4.10): paints and its thinners
Type of paint
Epoxy
Lake
Silk screen inks
Thermal inks
Polyurethane
Traffic paints
1.
2.
3.
1.
2.
3.
1.
2.
3.
1.
2.
1.
2.
1.
2.
Thinner solvents
Xylene;
Xylene + Methanol;
Xylene + Iso- Butanol.
White spirit;
White spirit + xylene;
Xylene + Toluene.
Butyl glycol;
Ethyl glycol;
Butyl glycol + Ethyl glycol.
Ethyl glycol;
Toluene + Methanol.
Xylene;
Toluene.
Toluene;
Toluene + Methanol.
24
Chapter Five
Testing paints
5.1: Introduction
Testing is an important part of the operation of a paint system. Testing is
done to monitor the system and to confirm that the finish meets established quality
standards and the expectations of the customer. The end use of a painted product
should determine what tests are important. The incoming paint material is
sometimes tested to confirm that the color and gloss are correct and the paint is
free of defects. In some cases, the paint supplier will certify that the paint they are
providing meets all required physical properties, [2].
5.2: laboratories mission
laboratories, in paint industry are responsible for; testing raw materials for
compliance with required standards, quality control of products to check
agreement with standard specifications, check the physical, chemical, and
mechanical properties of final products. Chemicals, including hazardous
materials, are used in laboratories. storage and handling should be checked by the
inspectors, in addition to the disposal of chemicals empty containers, which is
considered as hazardous waste, [10].
5.3: Raw material checking
Usually in paints industry the raw materials be got from several suppliers,
so that it needs to be tested and compared with the manufacturer standards.
Several tests done to paint components such as; resin, solvent, pigment……etc.
5.3.1: Solvent Tests
Solvent is the material that dissolve all components of paint following the
role; (Like dissolves like), the manufacturer must be sure that the solvent has
agreement to his standards by applying tests such as density, vaporization time,
and flash point each of this tests will be described in some details in the following
sections.
5.3.1.1: Density Test
By using density cup, which showed in figure (5.1), with volume about 100
ml, that first put empty on the balance to make the balance on zeroes state after
that the cup filled by the solvent and weighted again. The target from this test is
to know if the solvent mixed with another component or no.
25
Figure (5.1): cup used in measuring density
Vaporization time
it’s a second test also used to be sure that solvent does not mix with other
materials by boiling the solvent and counting the rate that solvent take to vaporize,
and the vaporizing time will be calculated according to the following low;
vaporization time = (Rate of solvent vaporization / Rate of ether vaporization)
the rate of ether vaporization is selected as standard as its equality to unity.
Flash point
It defined as the minimum percentage flash enough to the solvent to burn,
every solvent has a standard value to flash point which indicate that if the solvent
is pure or it mixed with another material.
5.3.2: Pigment test
It’s the test that done to know the amount of binder and resin required to
absorb definite amount of pigment by using a glass board and mixing manually
resin and solvent that already mixed before with pigment powder on this board,
an additional amounts of mixture from resin and solvent will be added until all
tested amount of pigment powder will mixed.
5.4: Final Products tests
several tests done to final product to check the degree that it agrees with
required specification, these tests used to put standards value for the organization
or company to distinguish its products.
26
5.4.1: Viscosity test
One of tests that applied to paints is viscosity, it can be determined by
measuring the time required for a given quantity of paint to flow through a hole
in the bottom of a metal cup, [2], it also can be measured by a visco-meter to
obtain paint viscosity.
Manual measuring of viscosity;
It’s simple method in which a cup with hole has diameter 4mm is used,
which showed in figure (5.2), the sample put into the cup and a stop watch is used
to measure the time that sample take to get out from the cup through the hole.
Figure (5.2): Measuring viscosity by using cup 4 device
Automatic measuring of viscosity;
This method is easy also as it doesn’t take the time that the first one takes,
by using a visco-meter device which give direct value of viscosity dependent on
a spindle rotate in the sample, which showed in figure (5.3).
Figure (5.3): Measuring viscosity with visco-meter
27
5.4.2: Density test
It’s the second important test after viscosity. It done by using cup has
volume of 100 ml, which shown in figure (5.1), the sample put into this cup
without leaving any spaces in cup, then the density measured by a digital balance.
Experiment of measuring density;
A primer alkyd sample came to laboratory from production line to apply
tests on it before packaging. one of these tests is the density test the cup filled by
the paste from sample, according that the initial weight of cup is 252 gm, the new
weight is 405 gm so the sample weight and packaging factor can be calculated as
following;
Wi= 252 gm, Wf= 405 gm, then sample weight = Wf – Wi = 405 – 252= 153gm.
Which mean that this paint can be filled with rate of 1530 gm/liter. So, the
standard value of filling can be calculated from this law;
Weight of pastel = Pastel volume * weight for 1liter……………….equation (5.1).
5.4.3: fineness test
It’s a test applied to test how surface will be smooth after it painted with a
definite type of paints. A hegman plate, which as shown in figure (5.4), is a steel
plate scaled in micron, used in this test.
Figure (5.4): Measuring fineness with hegman device
5.4.4: Hiding power
This test used to indicate how the film of paint will cover the coated surface
by it, and don’t appear anything from the surface that coated by this paint. By
using a film from card board and pulling tool which showed in figure (5.5), which
has different measurement for pulling in micron, which obtained in figure (5.6).
28
Figure (5.5): different shapes of pulling tools
Figure (5.6): Pulled film
After pulling the film of paint on paper test an opacity meter, such that
which obtained in figure (5.7), used to obtain the degree of paint hiding
Figure (5.7): measuring of hiding power by opacity meter
5.4.5: Gloss Test
Gloss meaning the degree by which film reflect the beams that fall on it, or
in another meaning the degree of paint of film shining, a statistical gloss meter,
such that which obtained in figure (5.8), used to obtain gloss degree which usually
in range varying from 20 to 90 degree.
29
Figure (5.8): Measuring of gloss degree using gloss meter
5.4.6: Acid value
It’s the value that indicate the amount of free fatty acids in an oil, this test
is important because the more this mentioned amount increase this led to
decreasing the drying rate. It can apply by titration experiment a suitable alkaline
material usually KOH, be put into burette and the oil put into the flask under
burette solubilized in 50 ml of ethanol, phenol phthalein will be used as indicator
which its color change from colorless to pink color, the value of free fatty acids
got from the following law;
Acid value = (titrated volume*Normality*M. wt of KOH) / (mass of sample)
5.4.7: Adhesion force
It describes how the film adhered to the surface that it painted using this
film, which considered one of important paint properties to consumer
expectations. Several methods used for testing the film adhesion force such as
using crystal brand transparent tape or using aluminum substrates, also this test
can be done using a simple method that is scratching the pulled film that showed
in figure (5.6).
5.4.8: Storing effect
A test using to ensure that the paint will stand against storing conditions by
putting a sample of paint into drying furnace with temperature 60 degree for two
weeks. If one of these conditions appear after the mentioned two weeks, it will
refer to non-standing against string effects, this conditions such as settling of solid
content, non- homogeneity of film, formulated skin over paint.
5.4.9: Drying rate
It’s one of important paint properties to consumer, which determine the
time that solvent need to volatile and in same time the dryer solidify the film on
painted surface, it simply can done by observation a pulled film and accounting
the time that it takes to be dry, it must compared with company standards.
30
5.4.10: Wash-ability test
It’s the resistance of paint film for washing, which done by a device, which
is shown in figure (5.9), that drop water with a regular rate and by using number
of brushes that rub the film and the time counted until film is removed.
Figure (5.9): Wash-ability testing device
5.4.11: Impact Resistance test
It used for measuring the film strength against exposing to hard shocks, the
method of testing that a standard weight hit a painted panel from a definite hight
such that which obtained in figure (5.10).
Figure (5.10): Measuring impact resistance from a hight 60 cm
31
Chapter Six
Conclusions
(1) Paints is a main type of coatings, used in purposes of protection, and
decoration. An example is epoxy and poly urethane system, paints has several
methods for applying such as spray gun.
(2) paints composed mainly of five components; resin (binder), which collect all
the rest of paint components, it classified to convertible binders such as; epoxy,
and polyurethane. The other classification is non-convertible binders such as;
cellulose, and nitro-cellulose.
(3) The second component is the solvent; which used to dissolve all components
of paint. Other components used such as pigment which give the paint its color,
the filler which perform usually half of formula amount, and finally some
additives such as thickeners, dryers, anti-foaming agents, and other additives
which obtained in table (2.3).
(4) Paints manufacturing depend on three-unit operations which are; mixing,
milling, and filtration. Mixing operation used for mixing all components and
homogenizing it, by using two mechanisms which are; liquid-liquid mixing, and
solid-liquid mixing. Milling operation is used to damaging all agglomerated
particles to prevent its settling. Filtration is used to remove any agglomerated
particles or anything before filtration.
(5) Equipment used in paints manufacturing are mixers, mills, and filters. Mixers
is consisting of impeller, consist of axis and radial or axial disk, and vessel which
must not contain baffles inside it for not reducing vortex, which is important in
solid-liquid mixing. Mills used to damage any coagulated particles, by crashing it
with macro balls manufactured from several materials such as; glass, and
ceramics. Screen filters are used for purification of paint.
(6) Paints manufacturing pass through several procedures, be in cleaning of
industrial units, and start adding the resin, solvent, thickener, and anti-settling
agent to provide pre gel phase to contain powders, that will be added and mixed.
After that, a sample sent to QCL to test it fineness, and after that the rest
components added, mixed well and milled, filtrated, and packaged. During and
after manufacturing processes several test done such as density, and viscosity test.
32
References
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McGraw-Hill book company, Tokyo.
2.[2] Rodger Talbert, 2008, Paints Technology Handbook, Taylor & Francis
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3.[3] R. LAMBOURNE and T.A. STRIVENS, 1999, Paint and surface Coatings
theory and practice, second edition, Woodhead Publishing Ltd, Cambridge.
4.[4] Charles A. Harper and Edward M. Petrie, 2003, Plastics Materials and
Processes A Concise Encyclopedia, John Wiley & Sons, New Jersey.
5.[5] Robert O. Ebewele, 2000, Polymer Science and Technology, CRC Press,
Florida.
6.[6] BRYAN ELLIS, 1993, Chemistry and Technology of Epoxy Resins,
Springer Science + Business Media Dordrecht, United Kingdom.
7.[7] Charles E. Carraher, Jr., 2003, Polymer Chemistry, MARCEL DEKKER,
NEW YORK and BASEL.
8.[8] Lyle F. Albright, 2009, Albright’s Chemical Engineering Handbook, Taylor
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united states of America.
10.[10] Ministry of state for environmental affairs, 2002, Paint Industry- SelfMonitoring Manual, Egypt.
33
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