TITLE: An eco-friendly composition of corrosion resistance self healing coating on
steel substrate.
FIELD OF INVENTION:
This invention relates to an eco-friendly composition of corrosion resistance coating on
steel substrate.
Further, this invention also relates to development and characterization for the
preparation of corrosion resistance self healing thin organic coating on steel substrate.
BACKGROUND OF THE INVENTION:
Corrosion is a well known problem relating to metallic structure, for example steel.
Different approaches may be involved in order to prevent or reduce corrosion. Out of
different approaches protective coating on metal surface plays an important role.
Protective coating for steel sections is typically based on paints, organic layers, ceramic
and inorganic layers, plastic lining and electroplating. Protective coating system might be
very effective in protecting uniform corrosion, but same coating system might fail
significantly in defect area. In contrast, metallic coating like zinc, aluminium- based
metal, magnesium based metal are distinguished by the fact that they have a tendency to
corrode more faster than the surface to be protected (steel surface) these types of coatings
are therefore also termed as sacrificial coating and are capable for healing the minor
cracks or damage area. In fact for better corrosion prevention we need a good defense
strategy which will provide good barrier protection and should take care of micro and
small cracks.
Having been inspired by nature scientists from various discipline to coating designers,
who wish to produce much more than conventional coatings, i.e. to convert the traditional
'dumb' coating into the 'smart or intelligent' coating. Self-healing is one of the examples

of smart coating. When coatings get damaged in the form of cracks induced by
mechanical, thermal and chemical means, regardless of the application, the integrity of
the structure is significantly compromised. Since, the damage deep inside material are
difficult to perceive and to repair in particular, the material would be motivating to have
ability of self-repairing through various stimuli response based on physical, chemical,
mechanical or thermal means which trigger the healing process. These progresses have
now opened an age of new intelligent materials. Continuous efforts are made to mimic
natural materials and to integrate self-repairing capability into polymers and polymer
composites. Keeping all this in mind self healing concept have drawn considerable
research interest in last few years. Healing is achieved by incorporating healing agents
and a catalyst chemicals trigger with in a polymer matrix. When coating is damaged by
mishandling or misuse of the coated structure healing agents present in polymer network
react with environment and heal the damage area.
In short, self-healing material provides the following advantages over the conventional
coating:
i) Automatic repairing process
ii) Barrier protection of underlying substrates
iii) Auto-preservation of aesthetics of surface appearance of coatings, plastic and
films
iv) Restoration of scratch resistance properties of coated materials
Microcapsule mainly contains some active reactive material which may be liquid, solid or
gas and these chemicals are known as core material. The core material is covered with
some hard material, known as shell.

Unless right chemistry is used to fabricate the active ingredients and its contents, it may
mix before the coating is applied or, upon mixing time. Again, unless the microcapsules
is compatible with both its active ingredients, polymer resin and solvent used for coating
application, life of the applied coating may be less than the desirable value.
Primer paint is mixed with microcapsules (60-150 microns diameter) and applied by
brushing or rolling. After the coating has cured, any physical compromise of the coating
results in microcapsules bursting to release liquid that fills and seals the compromised
volume. (Patent No. U.S. 7,342,057). Self-healing coating comprised of at least one
liquid COTS coating; and microcapsules, the volume contains at least one repair
substance, the microcapsules wet mixed into the liquid COTS coating just prior to
application of the self-healing coaling, wherein the shell is resistant to degradation by the
repair substance; the microcapsules are resistant to short term degradation by the liquid
COTS coating; and wherein the microcapsules in the area of a physical compromise of
the applied and cured self-healing coating burst, releasing the at least one repair
substance to fill and seal the compromised volume within the self-healing coating (Patent
No. U.S. 7,192,993 Bl). A coating includes coating encapsulated micro-spheres which
maintain the coating in a fluid state. Damage to the coating form a fissure which breaks
open the coating encapsulated micro-spheres adjacent the fissure. The broken coating
encapsulated micro-spheres release the fluid coating material contained therein. Because
the coating encapsulated micro-spheres release the encapsulated coating material in the
fluid state the coating material flows into the fissure to coat the exposed substrate. This
provides a "self-healing" ability to the coating which protects the substrate even after the
coating is damaged (Patent No. U.S. 6420052). A protective composite thin film coating
structure is disclosed which provides ultraviolet (UV)-protection to polymer components
used in low earth orbit environments. The structure protects such components from
physical and optical degradation due to exposure to ultraviolet radiation and oxygen, in
particular atomic oxygen. (Patent No. U.S. 5790304)

A liquid self-healing coating, incorporating microcapsules filled with tailored repair
formulations, repairs itself upon physical compromise after curing. In one embodiment, a
commercially available paint primer is mixed with a pre-specified amount of these
microcapsules. After the coating has cured on the substrate to which it is applied, any
physical compromise of the cured coating results in the microcapsules bursting to release
a liquid that fills and seals the compromised volume of the coating. In applications where
paint is used to provide corrosion protection, the liquid contains anti-corrosion material
as well as suitable diluents and film-forming compounds. In another embodiment, the
microcapsules may be provided separately to enhance commercially available products.
For example, if a paint formulation is known a priori, specifically configured
microcapsules packaged separately from the paint and designed for use with the paint
formulation, may be added to the commercially available product just prior to application
(Patent No. U.S. 7,192993)prior Art:
OBJECTS OF THE INVENTION:
An object of the present invention is to propose an eco-friendly composition of corrosion
resistance coating for steel substrate;
Another object of the present invention is to develop suitable coating which can provide
self healing property;
Still another object of this invention is self healing paint provide a uniform coating on
steel surface;
Further object of this invention is to provide a self healing coating composition which can
dry below 90°C within less than 30 sec;

Still further object of this invention is to propose a coating, which provide a good
resistance to saline atmosphere and coating has good corrosion resistance properties;
The further objects of the invention will be apparent to a reader on reading, the ensuing
description in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE INVENTION:
According to this invention there is provided an eco-friendly composition of corrosion
resistance coating for steel substrates comprising:
10-60% by weight is sol-gel solution
0.5-2% by weight is Nano pigment
0.5-2% by weight is Flash rust inhibitor
1 to 20% by weight is active corrosion resistance pigment
0.5-5% by weight is Neutralizing agent
0.5-5% by weight is Flexibiliser
0.25-2% by weight is Defoamer and leveling agent .
the remaining part is De-meneralized water.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Fig 1: Shows the optical microscope picture of self healing coating CRCA sheet.
Fig 2: Shows the optical microscope picture of self healing coating Gl sheet.
Fig 3: shows the Salt spray photo of self healing coated CRCA sheet.
Fig 4: shows the Salt spray photo of self healing coated Gl sheet.

DETAILED DESCRIPTION OF THE INVENTION:
According to the invention, one or more of these objectives may be achieved by
providing a method for producing a self healing coating on steel substrate, comprising the
steps of:
- Providing a coating mixture comprising at least one organofunctional silanes group;
- Applying the mixture to the steel substrate;
- Curing the mixture, so as to provide a dense network structure of coating for temporary
protection of the substrate against corrosion.
In an embodiment of the invention the further component in the coating mixture may
comprise an aqueous solution of flash rust inhibitor. The flash rust inhibitor is used to
restrict or delay the onset of under film corrosion or pre cure corrosion. The flash rust
inhibitor is selected from compounds such as sodium nitrite, benzotriazole or its
derivatives and/or a mixture of several inhibitors.
In an embodiment of the invention, the coating mixture also comprises one or more of the
following compounds:
- corrosion resistance pigment. The corrosion resistance pigments are selected from
nano zinc oxide, nano silica, nano alumina, nano cerium oxide, zinc phiosphate, zinc
phosphate derivatives or any combination thereof,
- coating additives such as dispersing agent, leveling agents, defoamer;
- In order to increase the flexibility an additional additive like polyester urethane also
used in the coating formulation.
- active protection pigments like nano Zinc flake, zinc- Aluminium- Magmesium flake,
Zinc-Aluminium Flake are also used in the formulation. These active protection
pigments help to provide the self healing properties of the coating.

In applying the corrosion resistant self healing thin organic coatings compositions of the
invention to substrates, any of well-known coating methods such as dipping, spraying,
roll coating and brush coating may be employed. Although the coating weight of the
composition is not particularly limited, it is usually coated so as to give a coating
thickness of 1 to 100 micron.
The curing step is preferably incorporated in an existing process step. The choice of the
curing temperature depends on the requirements to the cure coating. Depending upon the
requirement peak curing temperature can be reduced to 80°C by incorporating some
additive containing polyimide derivative.
EXAMPLES;
The invention will now be further described by way of examples undertaken on steel
substrate panels.
The primary organofunctional silane compound used in the embodiments of the invention
includes hydrolised water soluble solgel solution prepared from sol, modified with
organofunctional silanes. Beside organofunctional group it also contains organic
functionality based on Si bond epoxy group. A further chemical component used in the
invention includes the ammonia or amine derivative which used for the adjustment of pH
value.


The primary organofunctional silane compound used in the embodiments of the invention
includes hydrolised water soluble solgel solution prepared from sol, modified with
organofunctional silanes like glycidoxypropyltrimethoxysilane(GPTMS) tetraethoxy
silane(TEOS), vinyl trimethoxy silane(VTMS). Beside organofunctional group it also
contains organic functionality based on Si bond epoxy group

The flash rust inhibitors are selected from compounds such as sodium nitrite,
benzotriazole, a mixture of several inhibitors, its composition is as follows:
10-25% of C12-C14 (2-benzothiazolylthio) succinic acid tert amine salts
10-25% of ethoxylated tridecylalcohol phosphate-comprising monoethanolamine salts
10-25% of zinc salts of branched (C6-C19) fatty acids
<2.5% of zinc salts of naphthenic acid
10-25% morpholine benzoate
Corrosion resistance pigment is selected from zinc phosphate or its derivative, barites,
calcium silicate.
The nano pigment is selected from zinc oxide, silica, alumina, cerium oxide or any
combination thereof.
Active corrosion resistance pigment is selected from Zinc flake, Zinc-Aluminium Flake,
Zinc-Magnesium-Aluminium Flake.
Aliphatic polyester polyurethane resin is used as a flexibiliser.
Commercial product and or silicon solution is used as a leveling and defoamer
Amine or its derivative is used as neutralizing agent.
When this formulation applied on steel surface, it provides temporary active corrosion
protection and self healing properties achieved within 8h of damage.

WE CLAIM:
1. An eco-friendly composition of corrosion resistance coating for steel substrates
comprising:
10-60% by weight is sol-gel solution
0.5-2% by weight is Nano pigment
0.5-2% by weight is Flash rust inhibitor
1 to 20% by weight is active corrosion resistance pigment
0.5-5% by weight is Neutralizing agent
0.5-5% by weight is Flexibiliser
0.25-2% by weight is Defoamer and leveling agent
the remaining part is De-meneralized water.
2. The composition as claimed in claim 1 wherein the said flash rust inhibitor is selected
from sodium nitrite, benzotriazole, a mixture of several inhibitors, its composition is
as follows:
10-25% of C12-C14 (2-benzothiazolylthio) succinic acid tert amine salts
10-25% of ethoxylated tridecylalcohol phosphate-comprising monoethanolamine salts
10-25% of zinc salts of branched (C6-C19) fatty acids
<2.5% of zinc salts of naphthenic acid
10-25% morpholine nenzoate
3. The composition as claimed in claim 1 wherein active corrosion resistance pigment is
selected from Zinc flake, Zinc-aluminium Flake and Zinc-magnesium - Aluminium
Flake.
4. The composition as claimed in claim 1, wherein the said size of active corrosion
resistance pigment are in the range of 100-800nm to 20 micron meter.

5. The composition as claimed in claim 1, wherein the flexibiliser is aliphatic polyester
polyurethane resin.
6. The composition as claimed in claim 1, wherein said leveling and defoamer is silicon
solution or its derivatives.
7. The composition as claimed in claim 1 wherein the nano pigment is selected from zinc
oxide, silica, alumina, cerium oxide or any combination thereof.
8. The composition as claimed in claim 1, wherein the said neutralizing agent is amine or
its derivative.
9. The composition as claimed in claim 1, wherein said solgel solution is prepared from
sol, modified with organofunctional silanes like
glycidoxypropyltrimethoxysilane(GPTMS) tetraethoxy silane(TEOS), vinyl
trimethoxy silane(VTMS) and Mercaptopropyl trimethoxy silane(MTMO).
10. The composition as claimed in claim 1 is applied on a steel substrate to obtain a
coating thickness of 1 to 100 micron after drying at 80-150°C for 30s to 1minutes.

ABSTRACT

An eco-friendly composition of corrosion resistance coating for steel substrates
comprising:
10-60% by weight is sol-gel solution
0.5-2% by weight is Nano pigment
0.5-2% by weight is Flash rust inhibitor
1 to 20% by weight is active corrosion resistance pigment
0.5-5% by weight is Neutralizing agent
0.5-5% by weight is Flexibiliser
0.25-2% by weight is Defoamer and leveling agent
the remaining part is De-meneralized water.