FIELD OF THE INVENTION
The present invention relates to a composition of high solids colored hybrid
insulating coating for application on the inner surface of galvanized steel sheets
(GI) for roofing applications.
BACKGROUND OF THE INVENTION
Galvanized Steel sheet is one of the most popular metal roofing materials for
both residential and commercial sector. However, one of the major
disadvantages of the metal roofing in warm weather is that they absorb and
retain high amount of heat causing warmer atmosphere inside the building and
consume more energy for cooling in air conditioned building. Since sustainability
is one of the important issues in the construction sector, there is a need for
identifying metal roof with energy-efficient cooling characteristics. Pre-painted
metal roof and cladding, sandwich panel, use of insulating materials below the
roofs is presently used in the building sector. Reflective and thermal insulation
coatings both are used to reduce solar gain on rooftops. Insulating coating
provide substantial resistance to heat flow. The composition and thickness of
insulation coatings/materials prevents roofs and substances from gaining heat,
making the surfaces less warmer. Application of thermal insulation coating on or
inside metal roof is the most effective way to improve the energy efficiency of a
home. Another advantage of the insulating coating/materials is that they provide
extra protection to the galvanized steel sheet roof besides providing aesthetic
appeal. Ceramic coatings have been used as heat reflective coatings on metal
sheet roofs since long. Several type of materials such as expanded polystyrene,
polyurethane foam, polyester fiber, phenolic foam, mineral wool, cellular/foam
glass, wood chip board, wood fiber board, wood wool board, expanded perlite

board, siliceous rich expanded particles are also being used for roof insulation.
Ceramer coatings are another popular alternative for developing low cost
insulating coating for steel roof. They are made of various materials such as coal
tar, asphalt, water glass, minerals fillers, ceramic and more recently materials
developed using nanomaterials. Various type of insulating materials and coatings
are reported [1-14] in the prior publications.
The development of Organic-Inorganic hybrid coatings holds as greater promise
for the roofing applications due to availability of wide array of polymeric/organic,
fillers and pigments for its formulations. The polymer family such as epoxy,
polyurethane, polyamide, phenol formaldehyde, water dispersible polymers can
be used in combination with fillers such as clay, perlite, calcium carbonate, zinc
oxide, other silica rich minerals and pigments such as titanium dioxide, iron
oxide, phthalocyanine, toludine red to develop various colorful, protective and
thermal insulating coating. Both water based and solvent based coatings has
been used for thermal insulation purposes. However, due to growing
environmental concern and dwindling petroleum resources requires an innovative
hybrid coating composition based on renewable resources and low cost
filler/other materials.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose a process of producing an
eco-friendly thermal insulation coating for application on the inner surface of
galvanized steel sheet for roofing applications.

Another object of the invention is to propose a process of producing an eco-
friendly thermal insulation coating for application on the inner surface of
galvanized steel sheet for roofing applications, which constitutes a colored hybrid
coating.
A still another object of the invention is to propose a process of producing an
eco-friendly thermal insulation coating for application on the inner surface of
galvanized steel sheet for roofing applications, which encompass uniformly
dispersed coating composition onto the inner surface of the roof-sheets to
provide good thermal insulation characteristics and maintain a cooler condition of
the covered area.
SUMMARY OF THE INVENTION
According to the invention, the thermal insulation coating is prepared by mixing
a renewable resource based polymer and silica rich material with plate like
characteristics with cellular voids. Both these ingredients are mixed thoroughly in
a ball attriator mill. To this mixture, other minor ingredients as described are
added to get the flow, color, drying, durability and other characteristics of the
coating. The coating is thereafter grinded till uniform dispersion of the coating is
obtained. This composition is mixed with a curing agent and a catalyst to get the
desired thermal insulating coating.
The present invention provides an innovative eco-friendly high solids (>90%)
hybrid insulating coating composition comprising of renewable resources based
polymer and silica-rich filler for the inner surface of galvanized steel sheet (GI)
for roofing applications. The uniformly dispersed coating composition shows

good thermal insulation, corrosion resistance, aesthetic appearance, impact
resistance, durability and flexibility.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 - Shows the IR-Spectrum of the polyol based on castor oil used
as a renewable resource polymer of the invention.
Figure 2 - Shows the NMR spectrum of the polyol used in the invention.
Figure 3 - Shows the structure of methylene diphenyl 4, 4"- diisocyanate
(MDI) used in the invention.
Figure 4- Shows the result of flexibility test carried-out on the inventive
coating composition when coated on a GI sheet.
Figure 5 - Shows the result of front and reverse impact test on a Gl-Sheet
coated with the composition of the invention.
Figure 6- Shows the result of drilling test conducted on a coated specimen of
Gl-sheet for roofing application.
Figure 7 - Shows the result of salt-Spray test conducted on a coated specimen
of the invention.

Figure 8 - Shows a 'thermogram' of the coating-free film of the invention
developed through thermo gravimetric analysis.
Figure 9 - Shows the Delta-T (thermal differential) of the coating of the
invention establishing thermal insulation properties.
Table 1 - Shows the composition of the thermal insulation coating of the
invention.
DETAILED DESCRIPTION OF THE INVENTION :
According to the invention, an eco-friendly high solids hybrid thermal insulation
coating for the inner surface of GI sheet is prepared using renewable resource
polymer and silica rich mater as the major component added with other minor
components. The thermal insulating coating has been evaluated for flexibility,
impact/durability and corrosion resistance characteristics. The functions and
characteristics of the materials used in the insulating coating formulation are
mentioned below :
a. The various polymers such as phenolic, epoxy, polyurethane, acrylic can
be used for thermal insulation coating development. The renewable
resource based polymer such as polyester, polyurethane, alkyd,
polyamide, imide can be preferred. More specifically the renewable
resource polyol based on caster oil and having a general structure as
under:


The polyols were characterized using IR an NMR spectroscopy and shown in
Figure 1 and 2 respectively.
The silica rich materials with plate like characteristics with microcellular void is
used which is having composition of Silicon Dioxide in the range of 70-75%,
Aluminum Oxide in the range of 12-15%, Sodium Oxide in the range of 3-4%,
potassium oxide in the range of 3-5%, Iron Oxide in the range of 0.5-2%,
Magnesium oxide in the range of 0.2-0.7% and calcium oxide in the range of
0.5-1%.
The other additives used are as under:
Titanium Dioxide : Titanium dioxide (TiO2) is a white pigment and in general
used to provide the hiding power in coating formulation.
Zinc Phosphate : Zinc Phosphate Zn3(PO4)2 is a pigment to provide the corrosion
resistance properties to the coating formulation.

Borax : Borax (Sodium borate, sodium tetra borate, or disodium tetra borate)
offer fire resistance properties to the coating formulation.
Dispersing agent : Alphox-200 is a clear liquid and used as an additive in coating
formulation. It improves the dispersibility of pigment and filler in paint
formulations and also shows good leveling characteristics.
Phthalocyanine: Phthalocyanine blue or phthalo blue is an important durable
organic pigment and being used to provide different blue shades to the coating
formulation.
Defoamer: It is silicone based antifoam agent and controls the foaming
characteristics of high solids polyurethane coating. In addition, provides better
wetting and dispersing characteristics to the coating.
Methylene diphenyl 4,4'-diisocyanate (MDI): It is one of the important ingredient
to make commercial polyurethane coatings. It reacts with hydroxyl group of the
polyols to form urethane and urea linkages based on NCO/OH ratio in the coating
formulation. The structure of MDI is shown in figure 3.
Catalyst: The catalyst is used for the faster curing of polyurethane coating. The
following two types of catalyst have been utilized (a) Di butyl tin Laurate:
C32H64Sn/(C4H9)2Sn(OOC(CH2)10CH3)2 and (b) Zinc acetylacetonate: (C5H7O2)4Zr
Thus, a high solid (90%) hybrid thermal insulation coating has been prepared
using the composition shown in Table 1. Two coating formulations are produced.
Formulation 1 - A4 size GI sheet and Formulation 2 -12 ft x 3 ft GI Sheet.


The coatings after preparation, were applied on properly cleaned or primed GI
substrate and the coatings were evaluated for different properties listed below,
a) Flexibility test: Flexibility test has been carried out using conical mandrel.
For this purpose the coating applied onto GI substrate has been subjected to
mandrel. A visual inspection has been carried out to the bend coated specimen.
No visual surface crack indicates the good flexibility characteristics of the thermal
insulation coating. The coating was intact on GI substrate after the test which
indirectly indicates the good adhesion properties of the coating. A representative
result is shown in Figure 4.

b) Impact test: Impact test has been carried out using Falling Weight
Impact Tester on the coated specimen. Impact test has been carried out on both
the coated as well as uncoated side of the test specimen. The test specimen has
shown good impact resistance and substantiates good adhesion properties of the
coating. The results are shown in Figure 5.
c) Drilling Test; Since the coated specimen is required for roofing
applications. Hence, a drilling test has been carried out on the coated test
specimen. The coating has passed this test without losing the adhesion which
indicates good drillability of the coating. The results are shown in Figure 6.
d) Salt Spray Test : Salt spray test has been carried out on the coated
specimen to observe the corrosion resistance properties of the thermal insulation
coating. Both cross hatched and fully coated specimen has been subjected to salt
spray test for 1000 hrs and the specimen has shown no corrosion. The results
are shown in Figure 7.
e) Thermal Stability of Coating : Thermal stability study of the coating free
film has been carried out using Thermo Gravimetric Analysis and the thermo-
gram is shown in Figure 8. As per the thermo-gram shown in Figure 8, the
coating is thermally stable up to 300°C without any appreciable weight loss. This
indirectly corroborates the thermal stability of hybrid insulation coating.
f) Delta T Test: The thermal insulation properties were studied by measuring
Delta T (thermal differential) using 200 Watt and Infrared (IR) bulbs as heating
source in a test chamber. The results are shown in figure 9.

The hybrid thermal insulation coating prepared according to the invention
exhibits thermal differential (delta T) of more than 14°C with good flexibility,
impact, drillability and corrosion resistance properties. The test data is not
intended to limit the reach and benefits of the invention. Any variation with the
same supported and described results are encompassed by the invention.
REFERENCE :
1. Tsukamoto et al. US patent, 0241446A1,2004 (US 2004/0241446A1),
Thermally insulating coating material, for refractory containing carbon.
2. Parker et al, US patent, 0221091A1,2005 (US2005/0221091A1)
Composition for producing a thermal insulation coating.
3. Perez-Hinojosa, US patent, 0152366A1, 2010. (US 2010/0152366A1)
Process for preparing a thermal insulation coating paint with flexibility and
lightness properties.
4. Martin C et al., US patent No. 2,001,912,1935. Thermal insulation.
5. Charles U et al. US patent no.2,888,357,1959. Thermal insulation material
6. Dominic D et al. US patent No.3, 373,074, 1968. Thermal roof insulation
and method of preparing an insulated built-up roof.
7. Dunn et al. US patent no.3,769,065, 1973. Method of coating perlite and
producing materials of construction.

8. Ruff et al. US patent No.4,212,755, 1980. Settle resistant loose-fill perlite
insulation comprising particles rendered slightly tacky by a coating
thereon.
9. Hacker, US patent No.4,303,450,1981. Sprayable insulation composition.
10. Billings, US patent No.4,304,704,1981. Thermal insulating material,
11. Luckanuck, US patent no.5,085,897,1992. Fire retardant insulation spray
coating method,
12. Morgan et al. US patent 5,474,806,1995. Coating surface of hydrophobic
microporous thermal insulation material,
13. Chen et al. US patent NO 6,251,971 Bl, 2001 Thermal insulation coating
for pipes,
14. Sandoval et al, US patent No. 6,398,976 Bl,2002. Coated roofing
insulation and roofing systems including such insulations,

WE CLAIM :
1. A composition of eco-friendly thermal insulation hybrid color coating for
application on the inner surface of galvanized steel sheets for roofing
application, the coating being produced in a ball-attraitor mill, and
comprising :
- a renewable resources based polymer in an amount of 150 gm to 2000
gms;
- a silica-rich material amounting to 60 gms to 800 gms;
- other additives such as titanium dioxide, zinc phosphate, borax, dispersing
agent, phlthalocyanine blue, defoamer, catalyst, and solvent in the
amount of 15 gm - 200 gms, 7.5 gm to 100 gms, 3 gms to 40 gms, 12.9
gm to 172.05 gms., 1.5 gm to 5 gms. 6 gm to 58.5 gms, 0.015 gm to
0.025 gms, and 13.46 gm to 210 gms respectively; and
- methylene diphenyl 4.4' - diisocyanate (MDI) in the range of 58.8 gm to
784.3 gms with NCO/OH ratio between 1:1 and 1:1, wherein the mixing of
the ingredients is conducted under ambient temperature in a ball attraitor
mill, wherein the renewal resources based polymer having a general
structure of


and wherein the silica reach material having a plate like characteristics
with microcellular void.
2. The composition as claimed in claim 1, wherein the renewable resource
based polymer is selected from a group consisting of polyester,
polyurethane, alkyd, polyamide, and imide.
3. The composition as claimed in claim 1, wherein the silica-rich materials
having a composition of silicon dioxide in the range of 70-75%, aluminium
oxide in the range of 12-15%, sodium oxide in the range of 3-4%,
potassium oxide in the range of 3-5%, iron oxide in the range of 0.5-2%,
magnesium oxide in the range of 0.2-0.7%, and calcium oxide in the
range of 0.5 - 1%.
4. The composition as claimed in claim 1, wherein the dispersing agent is
Alphox-200, wherein the defoamer is a silicone based antifoam agent, and
wherein the catalyst is DBTL or Zr. Acctylacetonate.

5. The composition as claimed in claim 1, wherein the MDI is enabled to
react with hydroxyl group of the polyols to form urethane and urea
linkage.

The invention relates to a composition of eco-friendly thermal insulation color
coating on the inner surface of galvanized steel sheets for roofing
applications. The high solid (< 90 %) hybrid coating composition consists of a
renewable resource based polymer and low cost silica rich materials with
good thermal insulation characteristics along with other properties required
for GI roofing. The coating has been prepared using polymer and silica rich
material with plate like characteristics with microcellular voids as major
components and other minor components were mixed in a ball-attriator mill
followed by curing agent to get the flow, color, drying and thermal stability.
The thermal insulating coating has been evaluated for flexibility,
impact/durability and corrosion resistance characteristics. The composition
also provides good aesthetic appearance to GI sheet.