Coil Coating
Coil Coating
Coil Coating
The companys Pat-Add range of coating additives includes wetting & dispersing agents,
defoamers, slip & leveling agents, rheology modifiers. Whilst keeping focus on environmental
sustainability, the company produces products using green raw materials that are APEO free
and have low or no VOC.
These products are multi functional and multi compatible, which simplifies the production
process, reduces the chance of errors and minimizes inventory thus improving cost effective-
ness.
Patcham has built a strong manufacturing and R&D infrastructure that enables the rapid
transition from concept to products. The company has strategically located technical service
laboratories, offices and representatives around the world to provide the most efficient
customer service. In addition, a well-developed robust supply chain network enables it to
deliver its products and services to customers around the globe with minimal lead-time.
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Contents
Introduction 1
Patcham additive package 2
Primers and backcoats 3
Topcoats 5
Black topcoat 6
Red topcoat 7
Blue topcoat 8
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Introduction
Coil coating is a continuous, automated process for coating metal before fabrication into end
products. A steel or aluminum substrate is delivered in coils from the rolling mills. The metal
coil is positioned at the beginning of the coating line and in one continuous process, the coil
is unwound, cleaned, treated, primed and painted before being coiled at the other end and
packaged for shipment to other industries to be fabricated into variety of end products. All
of this happens at up to 700 feet per minute!
The excellent top coat finishes in these coatings are directly influenced by the resins,
pigments and the additives used. Innovative additives from Patcham, designed to work with
pigments in various resins deliver the attributes necessary for the required topcoat
performance.
Dry
Exit accumulator
Uncoiler
01. Stitching the strip to the previous coil 07. Curing (often only 15 to 60 seconds)
02. Cleaning the strip 08. Cooling the strip
03. Power brushing 09. Top coating on one or both sides
04. Pre-treating with chemicals 10. Second curing
05. Drying the strip 11. Cooling down to room temperature
06. Applying primer on one or both sides 12. Rewinding of the coated coil
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Patcham additive package
Table 1: Patcham additives for coil coatings
On SOP
White pigment : 1-5
Top Coat Low structured carbon black : 30 to 50
Dispersing PatAdd DA 947
Polyester : Melamine High structured carbon black : 50 to 120
additive High Molar Volume polymeric
Inorganic pigments : 10-20
dispersing agent
Organic blue/green : 40-60
Organic red/violet/yellow : 30-70
Grinding stage
NB: Adhesion test is done as per ASTM D 3359-02 (tape test) and the pencil hardness test is done as per ASTM D 3363-00
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Patcham additive package - Primers and backcoats
The main role of primers is to provide good adhesion of the topcoat to the pre-treated
substrate. Primers have a crucial role in protecting the substrate from corrosion. Further-
more, primers are expected to be compatible with subsequent layers of coatings. Backcoats
on the other hand, have a dual function. They are formulated to have properties of both the
topcoat and a primer. Back coats are applied on the reverse of the metal sheet.
Pat-Add DA 1801
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Patcham additive package - Primers and backcoats
Table 2: Guide formulation of Pat-Add DA 1801 for coil coat primers/backcoats
Millbase Letdown
Saturated polyester 25.50 Melamine formaldehyde 13.00
Pat-Add DA 1801 0.75 Saturated polyester 10.00
Titanium dioxide 12.00 Epoxy resin 4.00
Barytes 5.50 Solvesso 150 5.35
Zinc phosphate 8.00 Acid catalyst 0.60
Talc 1250 5.00 Total 100.00
Fumed silica 0.30
Solvesso 150 10.00
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Patcham additive package - Topcoats
The ultimate goal of the multi step coil coating processes is to provide a fast, durable, cost
effective and a sustainable product with an exceptional topcoat finish to meet the approval of
the end use product manufacturers. The top coat is often required to be glossy or matt,
colored, flexible, particularly UV-resistant or have a combination of many different functions.
The additives highlighted below have been designed to work with the pigments and resins to
provide the desired topcoat finish
Pat-Add DA 947
Pat-Add LE 1070
Pat-Add AF 62
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Patcham additive package - Black topcoat
Table 4: Guide formulation for black topcoat
Mill base
Saturated polyester 20.00
Pat-Add DA 947 1.33
Black pigment 2.00
Solvesso 150 16.17
Fumed silica 0.50
Letdown
Saturated polyester 27.00
Melamine formaldehyde 18.50
Pat-Add LE 1070 0.30
Pat-Add AF 62 0.20
Acid catalyst 0.50
Solvesso 150 13.50
Total 100.00
DFT of primer 5m
80
12
70
10
60
53 52
Gloss Values
8 50
Color Values
6 40
4 30 25
20 21
2 20 18
0 10
DA 947 Ref A Ref B DA 947 Ref A Ref B 3 4
2 3
-2 Initial After stability 0
DA 947 Ref A Ref B DA 947 Ref A Ref B
L* 2.17 8.39 4.92 2.19 10.7 5.84 Initial After stability
b* 0.28 1.89 -0.16 0.0 2.53 1.05 Gloss values 20
o o
Gloss values 60
Figure 7 : Colour values of black topcoat Figure 8: Gloss values of black topcoat
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Patcham additive package - Red topcoat
Table 5 : Starting formulation coil coating red topcoat
Mill base
Saturated polyester 20.00
Pat-Add DA 947 3.38
Pigment red 254 4.50
Solvesso 150 13.37
Letdown
60
a* values
4 51
50
E
3 40
55.5 55.45
30 30
2
20
1 10
0
55 0
DA 947 Ref A Ref B
DA 947 Ref A Ref B
Initial
Figure 10: Colour values of red topcoat Figure 11: Gloss values of red topcoat
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Patcham additive package - Blue topcoat
Table 7: Starting formulation coil coating blue topcoat
Mill base
Saturated polyester 20.00
Pat-Add DA 947 2.63
PB 15:3 4.50
Solvesso 150 17.37
Organo clay thickener 0.50
Letdown
Saturated polyester 20.00
Melamine formaldehyde 20.00
10 1.2 100 99 92 89
1
Gloss Values
0 80
L* and b* Values
72
E
0.8 61
60
-10 49
0.6 40
-20
0.4 20
-30 0.2 0
L* b* Rub-out test,dE
Figure 13: Colour values of blue topcoat Figure 14: Gloss values of blue topcoat
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Rubout tests on panels
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Coil coating panels
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Notes
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Notes
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The information given in this booklet is intended for technical guidance without obligation. Ver. 1.0