Claims:We Claim:
1. Magnetic paint formulation capable of generating stable magnetic coating and free of any settling and sagging characteristics comprising a synergistic combination of particulate iron powder and compatible sagging and settling controlling rheology modifying thickener within a selective average particle size range of 3.5 to 44 µm of the particulate iron powder for coated film thickness of upto 60 microns.

2. Magnetic paint formulation as claimed in claim 1 wherein the wt. ratio of particulate iron powder to said compatible sagging and settling controlling rheology modifying thickener ratio is in the range of 50 to 80: 0.3 to 1.0 wt. %respectively.
3. Magnetic paint formulation as claimed in anyone of claims 1 or 2 comprising synergistic combination of ferromagnetic particles with average particle size in the range of 3.5 to 44 µm and organic rheological additive in selective ratio, which ferromagnetic particles when blended with polymeric paint systems changes the viscosity levels less than 30% as compared to changes in viscosity levels due to blending of additives including surfactant and rheological additives in said polymeric paint systems.
4. A magnetic paint formulation as claimed in anyone of claims 1 to 3 comprising ferromagnetic particle and organic rheological additive in the ratio range of 80-85:0.75-1 when the average ferromagnetic particle size is 3.5 to 44 µm and may optionally include zinc particles.
5. A magnetic paint formulation as claimed in anyone of claims 1 to 4 wherein said ferromagnetic particles are preferably selected from magnetite, Fe3O4 iron and its alloys with nickel and cobalt and mixtures thereof wherein said organic rheological additive is selected from polyurea in the range of ,0.3 – 1.0 % corresponding to the binders of present in the range of 15-35 % respectively favouring magnetic conservation characteristics of the magnetic paint formulation and stability of the same for at least 1 year when exposed to 90% humid conditions.
6. A magnetic paint formulation as claimed in anyone of claims 1-5 comprising zinc particles as Zinc powder with average particle size in the range of 11?m and in amounts of 5-10 wt.%.
7. A magnetic paint formulation as claimed in anyone of claims 1-6 comprising selective resin selected from PU, melamine, enamel, epoxy resin for adhesion to select substrates including wood, ply wood, wall, metals, fireboard and also includes oil paints.
8. A magnetic paint formulation as claimed in anyone of claims 1-7 comprising surfactants including polyols in the range of 0.2-0.5%, selective rheological additive based on the resin/binder involved in the range of 0.1-2.0 % and solvents in the range of 4 to 6 for blending with any oil-, latex-, or lacquer-based paint or coating to form a magnetic paint or coating having viscosity levels in the range of 80 poise to 30 poise at 25 ?C.
9. A magnetic paint formulation as claimed in anyone of claims 1-8 comprising
a) 15-25 wt. % resin;
b) 0.05 – 0.3 wt. % dispersant;
c) 4 – 6 wt. % solvent;
d) 50 – 80 wt. % ferromagnetic particles having particle size of about upto 44 µm;
e) 0.3 – 1 wt. % of poly urea as thickening agent; and
f) Optionally, 5 – 8 wt. % of Zn particles having average particle size of about 10 – 15 µm and 4-7 wt. % hardener.
10. A magnetic paint formulation as claimed in anyone of claims 1-9 for application by brush or spray application on surfaces including wooden surface, plastic board, fibre board, masonry, aluminium sheet and providing for at least three coats for dry film thickness of 50-60 microns with resulting magnetic flux density in the range of -120 ?T to -250 ?T also favouring a smoothened surface with increased gloss.
11. A magnetic paint formulation as claimed in anyone of claims 1-10 wherein blend of 15 -20% of Fe3O4 of average particle size 3.5 µm with 40-50 %Fe (0) powder having average particle size of about 44 µm favours improved surface smoothness of the resulting film wherein 20° angle increases from 0.1-0.3 unit to 0.7-1.1 unit for incorporation of magnetite with cast iron powder.

12. A process for manufacturing the magnetic paint formulation as claimed in anyone of claims 1-11 comprising the steps of
providing a synergistic combination of ferromagnetic particles with average particle size in the range of 50-65 ?m and organic rheological additive, and blending with polymeric paint systems such that changes in the viscosity levels when the ferromagnetic particles are added is less than 30% as compared to the change in viscosity levels due to blending of additives including surfactant and rheological additives in said polymeric paint systems.
13. A process for manufacturing the magnetic paint formulation as claimed in claim 12 wherein ferromagnetic particle and organic rheological additive is added in the ratio range of 80-85:0.75-1 optionally including zinc particles as Zinc powder with average particle size in the range of 11 ?m in the amounts of 5-10 wt.%.

Dated this the 9th day of September, 2016 Anjan Sen
Of Anjan Sen and Associates
(Applicants Agent)
, Description:FIELD OF INVENTION:
The present invention provides for a magnetic coating formulation suitable for wood coating and wall application which have no settling, sagging issues and have high stability together with improved magnetic conservation characteristics even in humid conditions. Particularly, the magnetic coating formulation comprises ferromagnetic metallic particles having average particle size ranging from 3.5 to 44 µm in combination with selective rheological additive in selective ratios in binder/resin dispersant, with or without Zinc favouring in addition to anti-settling and anti-sagging characteristics conserved magnetic properties upto at least one year.
BACKGROUND ART:
Magnetic pigments have been identified for addition in paint system for introducing magnetic properties (US3087832, EP0549849). Indeed some commercial products are also available in this category. However, most of them suffer from settling of pigments and low magnetic power of the coating. Furthermore, use of Iron powder in formulation may cause oxidation by atmospheric humidity and oxygen which in long term has the probability of decreasing the magnetic power of the coating.
Reference is drawn to US5609788 disclosing magnetic paint additive formulated from ferromagnetic particles having amixed particle range of from about 0.01 µ to about 74 µ, preferably from about 0.01 µ to about 37 µ to 44 µ with preferred iron powder that are blended together with a surfactant or surfactant mixture, or asurfactant and alcohol mixture, in amounts sufficient to suspend the particles to yield the additives that may be blended with any oil-, latex-, or lacquer-based paint or coating to form a magnetic paint or coating having a viscosity substantially similar to the paint containing no particles and/or additive.
US3087832 teaches a magnetic component of the magnetic coating composition dispersed in a binder material dissolved in a readily evaporable liquid vehicle to form a solution-dispersion that may be applied to a supporting web material and dried to a solid coating at room temperature.
US5843329 is directed to magnetic paint or ink additives are formulated from ferromagnetic particles, preferably iron powder, having a mixed particle range of from about 0.01 µ to about 297 µ, that are used in a latex that are also formulated by blending the particles with a surfactant, a surfactant mixture, or a surfactant and alcohol mixture to suspend the particles.
US7018557 B2 is directed to a aerosol paint product comprising:(a) a container comprising a can, a valve cup with a valve assembly, a dip tube and an actuator; and(b) a magnetic aerosol paint composition disposed within said container, said magnetic aerosol paint composition comprising:(i) at least one volatile organic solvent;(ii) at least one film-forming resin;(iii) ferromagnetic particles; and(iv) a propellant selected from the group consisting of ethers, C1–C4 saturated hydrocarbons, hydrofluorocarbons, and mixtures of the foregoing wherein the ferromagnetic particles are present at a level of at least 25% of the total weight of ferromagnetic particles, resin and organic solvent.
EP0730263A2 is directed to a magnetic paint usable in forming a magnetic layer of a magnetic recording medium which paint is excellent in dispersibility of magnetic particles and application property to a substrate which is capable of producing a magnetic recording medium excellent in running stability, durability, electromagnetic conversion property, and the like and comprises magnetic powder, one or more resin binders and organic solvents,
CN104449025 discloses a method for producing an oil paintby adding 1/5 of polyurethane acrylic resin followed by adding conductive carbon black, chlorinated paraffin, magnetic iron powder, zeolite powder and nickel powder, adding part of polyurethane acrylic resin at an interval of 1 minute, and completely adding the residual polyurethane acrylic resin for 3-4 times; adding a mixed solution of double distilled water, butanol, an organic silicone resin fluid and an isocyanate adhesive to a second cylinder, and carrying out hydrolytic crosslinking reaction; and adding nano powder, and carrying out catalytic reaction, mixing the materials which are processed in the first cylinder and the second cylinder at the ratio, thus various defects of the oil paint can be improved and wherein the method is economic and applicable.
CN104342032 (A) teaches Iron Powder Paint characterized in that 23 percent of iron powder is added into the paint wherein the characteristics of the paint are not changed, and the paint has magnetic adsorbability after being coated or brushed on a wall or furniture, so that a decoration with a magnet can be directly suspended, the position of the decoration can be changed at any time, and the wall or furniture cannot be destroyed after the decoration is removed.
CN104312242 (A) discloses anti-rust paint, in particular to magnetic antirust epoxy top-coatcontaining secondary reduced iron powderwherein the magnetic antirust epoxy top-coat is prepared from the raw materials in parts by weight: 40 to 50 parts of epoxy resin, 28 to 34 parts of polyamide resin, 2 to 3 parts of boron carbide, 1 to 3 parts of N-isopropylacrylamide, 1 to 2 parts of polyglutamic acid, 3 to 5 parts of secondary reduced iron powder, 5 to 8 parts of aluminum dihydrogentripolyphosphate, 12 to 15 parts of mica powder, 1 to 3 parts of dimethyldichlorosilane, 8 to 10 parts of ethyl orthosilicate, 2 to 3 parts of 4-dimethylaminopyridine, 20 to 25 parts of butyl acetate, 10 to 14 parts of normal butyl alcohol, 18 to 22 parts of an antirust pigment, and 2 to 3 parts of an additive.
US5587102 teaches magnetic paint composition comprising a carrier, particulate magnetically permeable material, a binder, and a thickening agent involving inorganic thickening agent such as smectite clay having thixotropic and viscosity characteristics such that the paint composition has high viscosity when stationary, and low viscosity when shear forces to the paint composition, as it is being applied to a wall surface.
US5609788 discloses a magnetic paint additive that are formulated from ferromagnetic particles preferably iron powder having a mixed particle range of from about 0.01 µ to about 74 µ, preferably from about 0.01 µ to about 37 µ to 44 µ that are formulated by blending the particles with a surfactant or surfactant mixture, or a surfactant and alcohol mixture, in amounts sufficient to suspend the particles. The additive may be blended with any oil-, latex-, or lacquer-based paint or coating to form a magnetic paint or coating having a viscosity substantially similar to the paint containing no particles and/or additive and coats surfaces such as wood, wall board, sheet rock, foam, plywood, plastic, fiberboard and the like so coated may be cut with conventional wood working tools to form magnetic signs.
US 5843329 teaches a magnetic paint or ink additive and coating thereof are formulated from ferromagnetic particles, preferably iron powder, having a mixed particle range of from about 0.01 µ to about 297 µ, and preferably to about 250 µ and more, preferably from about 0.01 µ to about 37 to 44 µ; 6 to 20 µ particles are used in one latex-based embodiment. The additives may be blended with any oil-, latex-, or lacquer-based paint, ink, or coating to form a magnetic paint or coating having a viscosity substantially similar to the paint or ink containing no particles and/or additiveprovided in combination with a whitener selected from the group consisting of antimony oxide, zinc oxide, titanium oxide, zinc sulfate, and mixtures thereof, sufficient to lighten the coating.
Though many and varied, none of these prior patents disclose a magnetic paint or coating, or paint additive, that is simple to make and use, and inexpensive based on selective ingredients which when employed in selective amounts would on one hand, facilitate preservation of magnetic property over a long period of time even under extreme humid conditions, and on the other would render extra stability towards settling and sagging.

OBJECTS OF THE INVENTION
Thus the basic object of the present invention is to provide for a magnetic paint formulation involving ferromagnetic particles in selective form together with binder and additives including select rheological additives in selective amounts as a stable magnetic paint/coating.
Another object of the present invention is to provide said magnetic paint formulation that would have improved stability characteristics would be stable to anti-settling anti-sagging, and would have preserved magnetic properties over a long period of time of at least about 1 year even under extreme humid conditions.
Yet another object of the present invention is to provide for said magnetic paint formulation involving ferromagnetic particles with magnetic conservation characteristics with or without Zn that would act as a spacer between ferromagnetic particles.
Another object of the present invention is to provide for said magnetic paint formulation which would comprise selective resins to affect adhesion tovaried substrates.

SUMMARY OF THE INVENTION
According to the basic aspect of the present invention there is provided a magnetic paint formulation capable of generating stable magnetic coating and free of any settling and sagging characteristics comprising a synergistic combination of particulate iron powder and compatible sagging and settling controlling rheology modifying thickener within a selective average particle size range of 3.5 µm to 44 µm of the particulate iron powder for coated film thickness of upto 60 microns.
According to another preferred aspect of the present invention there is provided said magnetic paint formulation wherein the wt. ratio of particulate iron powder to said compatible sagging and settling controlling rheology modifying thickener ratio is in the range of 50 to 80: 0.3 to 1.0 wt. % respectively.
According to yet another preferred aspect of the present invention there is provided a magnetic paint formulation comprising synergistic combination of ferromagnetic particles with average particle size in the range of 3.5 µm to 44 µm and organic rheological additive in selective ratio, which ferromagnetic particles when blended with polymeric paint systems changes the viscosity levels less than 30% as compared to changes in viscosity levels due to blending of additives including surfactant and rheological additives in said polymeric paint systems.
It was thus surprisingly found by way of the present invention that when ferromagnetic particles in selective particle size together with binder and additives including selective rheological additive when employed in selective ratio the same provides for a stable magnetic paint formulation and a stable magnetic paint/coating thereof that is stable to settling for at least about 1 year irrespective of involving increased wt% of ferromagnetic particles in magnetic paint formulation, and also reveals conserved magnetic properties inspite of exposure to extreme humid conditions of about 90% humidity irrespective of addition of Zn particles and also possesses anti-sagging characteristics having viscosity in the range of 80 poise to 30 poise at 25 ?C.
It was also significantly found by way of the present invention that upon involvement of magnetite together with cast iron powder the smoothness of the paint drastically increases giving much higher gloss as compared to the sole addition of cast Iron Powder without compromising on overall magnetic performance of the film that may be attributed to better packing in the system. The 20° angle increases from 0.1-0.3, unit to 0.7-1.1 unit for incorporation of magnetite with cast iron powder.

Further a stable magnetic paint formulation is provided with and without the addition of Zn whereby Zn addition additionally conserves the magnetic property of the paint and also acts as a spacer between said ferromagnetic particles. It was also found by way of the present invention that the addition of ferromagnetic particles with or without zinc powder in preferred form including selective rheological additive in the paint systemis effected in conventional paint system such that the viscosity changes is less than 30 % as compared to the viscosity changes due to the additives including surfactants and rheological additives.
It is thus the special finding of the present invention that such selectively achievable viscosity levels of the magnetic paint formulation of 80 poise to 30 poise at 25 ?C is in turn selectively achieved based on the selective particle size and the selective critical ratio of the ferromagnetic particles and theselect rheological additive employed in said formulation. The viscosity of the paint formulation was thus selectively attained leading to a stable magnetic paint formulation which was adjusted to sprayable viscosity before application via addition of solvents in particular proportion. Such selective viscosity levels of the paint systems when not attained resulted in settling and sagging problems.
Preferably, in said magnetic paint formulation said ferromagnetic particle and organic rheological additive is present in the ratio range of 80-85:0.75-1 when the average ferromagnetic particle size is 3.5 µm to 44 µm and may optionally include zinc particles.
According to another preferred aspect of the present invention there is provided a magnetic paint formulation wherein said ferromagnetic particles are preferably selected from magnetite, Fe3O4 iron and its alloys with nickel and cobalt and mixtures thereof wherein said organic rheological additive is selected from polyurea in the range of, 0.3–1.0 % corresponding to the binders of present in the range of 15-35 % respectively favouring magnetic conservation characteristics of the magnetic paint formulation and stability of the same for at least 1 year when exposed to 90% humid conditions.
Preferably, in said magnetic paint formulation comprising zinc particles as Zinc powder with average particle size in the range of 11 ?m and in amounts of 5-10 wt.%.
More preferably, a magnetic paint formulation is provided comprising selective resin selected from PU, melamine, enamel, epoxy resin for adhesion to select substrates including wood, ply wood, wall, metals, fireboard and also includes oil paints.
According to yet another preferred aspect of the present invention there is provided a magnetic paint formulation comprising surfactants including polyols in the range of 0.2-0.5%, selective rheological additive based on the resin/binder involved in the range of 0.1-2.0 % and solvents in the range of 4 to 6 for blending with any oil-, latex-, or lacquer-based paint or coating to form a magnetic paint or coating having viscosity levels in the range of 80 poise to 30 poise at 25 ?C.
Preferably a magnetic paint formulation is provided comprising
a) 15-25 wt. % resin;
b) 0.05 – 0.3 wt. % dispersant;
c) 4 – 6 wt. % solvent;
d) 50 – 80 wt. % ferromagnetic particles having particle size of about upto 44 µ;
e) 0.3 – 1 wt. % of Poly Urea as thickening agent; and
f) Optionally, 5 – 8 wt. % of Zn particles having average particle size of about 10 – 15 µm and 4-7 wt. % hardener.

Preferably a magnetic paint formulation is provided for application by brush or spray application on surfaces including wooden surface, plastic board, fibre board, masonry, aluminium sheet and providing for at least three coats for dry film thickness of 50-60 microns with resulting magnetic flux density in the range of -120 ?T to -250 ?T also favouring a smoothened surface with increased gloss.
According to another preferred aspect of the present invention there is provided a magnetic paint formulation wherein blend of 15 -20% of Fe3O4 of average particle size 3.5 µm with 40-50 % Fe (0) powder having average particle size of about 44 µm favours improved surface smoothness of the resulting film wherein 20° angle increases from 0.1-0.3 unit to 0.7-1.1 unit for incorporation of magnetite with cast iron powder.

According to another preferred aspect of the present invention there is provided a process for manufacturing the magnetic paint formulation comprising the steps of
providing a synergistic combination of ferromagnetic particles with average particle size in the range of 50-65 ?m and organic rheological additive, and blending with polymeric paint systems such that changes in the viscosity levels when the ferromagnetic particles are added is less than 30% as compared to the change in viscosity levels due to blending of additives including surfactant and rheological additives in said polymeric paint systems.
Preferably in said process for manufacturing the magnetic paint formulation said ferromagnetic particle and organic rheological additive is added in the ratio range of 80-85:0.75-1 optionally including zinc particles as Zinc powder with average particle size in the range of 11 ?m in the amounts of 5-10 wt.%.

DETAILED DESCRIPTION OF THE INVENTION:
As discussed hereinbefore the present invention is related tomagnetic paintwhere ferromagnetic metallic particles when blended with a selective rheological additive with or without anti corrosive particlein resin binders selected from polyurethane, epoxy, acrylic, urea formaldehyde, and polyester derived polymeric systems with other wetting and rheological additive under high sheer, a magnetic paint formulation could be achieved that is stable to settling for at least about 1 year and also possesses anti-sagging characteristics together with conserved magnetic properties not impacted by exposure to extreme humid conditions even about 90% humidity. The viscosity of the formulation was found to be in the range of 80 poise to 30 poise at 25 ?C. The applications of these paint can be performed either by spray application or by brush application on any type of substrate including wooden surface, plastic board, fibre board, masonry, Aluminium sheet etc. nonmagnetic substrates which is eventually endowed with magnetic property.
The present invention is based on finding suitable composition of a paint formulation in which ferromagnetic pigments in form of iron powder of different mesh size, its alloys along with or without anti corrosive and selective rheological additive in combinationin selective amounts forms an inexpensive highly stable paint and coating which upon drying form a coating able to attract magnets. Preferred additives are ferromagnetic particles, optionally zinc powder, surfactant, and rheological additives.
In general Iron or its Nickel and Cobalt alloy powder of mesh size 250 or greater was preferred, which were grinded with Zinc powder and then mixed with surfactant binder and rheological additive. Increase in mesh size of the Ferromagnetic additive increases oil absorption value thus for a particular formulation the paint viscosity increases which affects the finish and surface smoothness of the coating. While decreasing the mesh size results increase in the particle size thus affecting the finish of the coating by higher surface roughness. Therefore, an optimum mesh size range of the additives must be used for achieving smoother surface with good magnetic property.
To achieve better results on conventional surfaces such as wall, interior/exterior wood coating, and preferred particle size varies from 44 µm to 0.01 µm with average particle size ranging from 44 µm. These particles were dispersed in preferably non aqueous solvent containing binder and surfactant. The dispersion was carried out in high speed stirrer with stirring rate 1200 to 1600 rpm for 30 minutes. To it co-solvents if required were added followed by addition of rheological additive. This mixture was also stirred under high speed stirrer at 1000-1200 rpm for 15 minutes.
After completion of paint formulation it was left at ambient condition for one week to check the settling of the pigments. This is called base of paint. Before application of the paint (if required) hardener was optionally, added and diluted accordingly. This paint was then matured for 1 hour then applied on surfaces by spray application. Depending on the hardener and binder ratio different gelation time was observed which generally greater than 3 hours. After application the paint it was dried for one day.
Enamel, epoxy and poly urethane (PU) has been used as binder for all these paint systems. Magnetite, Iron and its alloys with nickel and cobalt is preferred with zinc powder for prevention of corrosion from pigment and to maintain long term magnetic property. Wetting additives with surfactant and thickener was used in the paint formulation. The viscosity of the paint formulation was relatively in higher range open to adjustment to spray-able viscosity before application via addition of proper solvent in particular proportion. The paint formulations of the present invention may preferably comprise 50 to 80% of magnetic pigments of average particle size ranging from 3 µm-44 µm with or without 5 to 10% of Zn dust and about 2% of rheological additive including surfactants. The pigment and the coating there after was characterized by particle size analysis and Bohr Magnetron for its magnetic property measurement.
BRIEF DESCRIPTION OF FIGURES
Figure 1: illustrates Bohr Magnetron measurement of 350 mesh Fe (0) particles;
Figure 2: illustrates Bohr Magnetron measurement of Fe (0) particles 250 to 300 mesh;
Figure 3: illustrates Bohr Magnetron measurement of Fe (0) particles 500 mesh;
Figure 4: illustrates Bohr Magnetron measurement of Fe (0) ultra fine particles;
Figure 5: illustrates Bohr Magnetron measurement of Fe3O4;
Figure 6: illustrates Bohr Magnetron measurement of Fe-Ni alloy;
Figure 7: illustrates Bohr Magnetron measurement of Fe-Co alloy.

EXAMPLES
Example 1: (350#)
In a stainless steel vessel 20-30 % of polyol polymer dispersion in anhydrous solvent (such as mix xylene and mineral turpentine oil) (50 wt %) was taken and wetting additive was added. This mixture was stirred for 15 minutes by using a crown disk stirrer with a help of overhead mechanical stirrer. Magnetic pigment, Cast Iron Fe (0) 350 mesh powder having average particle size of about 44 µm was added in 50-70 %. The Bohr magnetron measurement of this material shows a magnetic flux density of – 156.73 µT (Figure 1). After that co solvents like butyl acetate and mix xylene were added before addition of 0.3-0.7 wt % rheological additive and 0.05-0.3 wt % surfactant. This forms the base of the paint. Before application the paint was diluted by 5-10% and hardening agent was added if required and then sprayed on wooden, plastic and masonry surfaces. In general three coats of application shows satisfactory results.

Example 2: (350#+Zn)
In a stainless steel vessel of 20-30 % polyol polymer dispersion in anhydrous solvent (50 wt %) was taken and wetting additive was added. This mixture was stirred for 15 minutes by using a crown disk stirrer with a help of overhead mechanical stirrer. Magnetic pigment, Cast Iron Fe (0) 350 mesh powder having average particle size of about 44 µm was added 50-60 %. Then Zinc dust having particle size 2-30 µm were added 5-6%. After that co solvents were added before addition of 0.3-0.7 wt. % rheological additive and 0.05-0.3 wt % surfactant. This forms the base of the paint. Before application the paint was diluted by 5-10% and hardening agent was added if required and then sprayed on wooden, plastic and masonry surfaces. In general three coats of application shows satisfactory results also with regard to the flux density attained.

Example 3: (250-300#)
In a stainless steel vessel 25-30 % of polyol polymer dispersion in anhydrous solvent (50 wt %) was taken and wetting additive was added. This mixture was stirred for 15 minutes by using a crown disk stirrer with a help of overhead mechanical stirrer. Magnetic pigment, Iron Fe (0) 250-300 mesh powder having average particle size 64 to 44 µm was added in 50-65 %.The Bohr magnetron measurement of this material shows a magnetic flux density of – 223.28 µT (Figure 2). After that co solvents were added before addition of 0.3-0.7 wt % rheological additive and 0.05-0.3 wt % surfactant. This forms the base of the paint. Before application the paint was diluted by 5-10% and hardening agent was added if required and then sprayed on wooden, plastic and masonry surfaces. In general three coats of application shows satisfactory results.
As 250 to 300 mesh size is higher (particle sizes are bigger than 44 ?m) than 350 mesh (44 ?m or less size), it was found that a much coarser coating resulted with film thickness more than 60 ?m which is not desired.

Example 4: (250-300#+Zn)
In a stainless steel vessel of 20-30 % polyol polymer dispersion in anhydrous solvent (50 wt %) was taken and wetting additive was added. This mixture was stirred for 15 minutes by using a crown disk stirrer with a help of overhead mechanical stirrer. Magnetic pigment, Iron Fe(0) 250-300 mesh powder having average particle size 64 to 44 µm was added 50-60 %. Then Zinc dust having particle size 2-30 µm with an average size of 11 µm were added 5-6%. After that co solvents were added before addition of 0.3-0.7 wt % rheological additive and 0.05-0.3 wt % surfactant. This forms the base of the paint. Before application the paint was diluted by 5-10% and hardening agent was added if required and then sprayed on wooden, plastic and masonry surfaces. In general three coats of application shows satisfactory results.
Similarly as 250 to 300 mesh size is higher (particle sizes are bigger than 44 ?m) than 350 mesh (44 ?m or less size), it was found that a much coarser coating resulted with film thickness more than 60 ?m which is not desired.
Example 5: (500#)
In a stainless steel vessel 30-40 % of polyol polymer dispersion in anhydrous solvent (50 wt %) was taken and wetting additive was added. This mixture was stirred for 15 minutes by using a crown disk stirrer with a help of overhead mechanical stirrer. Magnetic pigment, Iron Fe (0) 500 mesh powder having average particle size of about 28 µm was added in 45-55 %. The Bohr magnetron measurement of this material shows a magnetic flux density of – 185.61 µT (Figure 3). After that co solvents were added before addition of 0.3-0.7 wt % rheological additive and 0.05-0.3 wt % surfactant. This forms the base of the paint. Before application the paint was diluted by 5-10% and hardening agent was added if required and then sprayed on wooden, plastic and masonry surfaces. In general three coats of application shows satisfactory results.

Example 6: (500#+Zn)
In a stainless steel vessel 30-40 % of polyol polymer dispersion in anhydrous solvent (50 wt %) was taken and wetting additive was added. This mixture was stirred for 15 minutes by using a crown disk stirrer with a help of overhead mechanical stirrer. Magnetic pigment, Iron Fe (0) 500 mesh powder having average particle size of about 28 µm was added in 40-50 %. Then Zinc dust having particle size 2-30 µm with an average size of 11 µm were added 4-5 %. After that co solvents were added before addition of 0.3-0.7 wt % rheological additiveand surfactant 0.05-0.3 wt %. This forms the base of the paint. Before application the paint was diluted by 5-10% and hardening agent was added if required and then sprayed on wooden, plastic and masonry surfaces. In general, three coats of application shows satisfactory results, also with regard to the flux density attained.

Example 7: (EC10TR)
In a stainless steel vessel 30-40 % of polyol polymer dispersion in anhydrous solvent (50 wt %) was taken and wetting additive was added. This mixture was stirred for 15 minutes by using a crown disk stirrer with a help of overhead mechanical stirrer. Magnetic pigment, Fe (0) with ultra-fine particles having average particle size 14 µm was added in 45-55 %. The Bohr magnetron measurement of this material shows a magnetic flux density of – 166.31 µT (Figure 4). After that co solvents were added before addition of 0.3-0.7 wt % rheological additive and 0.05-0.3 wt % surfactant. This forms the base of the paint. Before application the paint was diluted by 5-10% and hardening agent was added if required and then sprayed on wooden, plastic and masonry surfaces. In general three coats of application shows satisfactory results.

Example 8: (EC10TR+Zn)
In a stainless steel vessel 30-40 % of polyol polymer dispersion in anhydrous solvent (50 wt %) was taken and wetting additive was added. This mixture was stirred for 15 minutes by using a crown disk stirrer with a help of overhead mechanical stirrer. Magnetic pigment, Fe (0) having average particle size 14 µm was added in 45-55 %. Then Zinc dust having particle size 2-30 µm with an average size of 11 µm were added 4-5 %. After that co solvents were added before addition of 0.3-0.7 wt % rheological additive and 0.05-0.3 wt % surfactant. This forms the base of the paint. Before application the paint was diluted by 5-10% and hardening agent was added if required and then sprayed on wooden, plastic and masonry surfaces. In general, three coats of application shows satisfactory results also with regard to the flux density attained.

Example 9: (Fe3O4)
In a stainless steel vessel 55-60 % of polyol polymer dispersion in anhydrous solvent (50 wt %) was taken and wetting additive was added. This mixture was stirred for 15 minutes by using a crown disk stirrer with a help of overhead mechanical stirrer. Magnetic pigment, Fe3O4 having average particle size 3.5 µm was added in 40-35 %. The Bohr magnetron measurement of this material shows a magnetic flux density of –81.60 µT (Figure 5). Before application the paint was diluted by 5-10% and hardening agent was added if required and then sprayed on wooden, plastic and masonry surfaces. The results were not satisfactory even if the particle size was within the desired range.

Example 10: (FeNi 500#)
In a stainless steel vessel 30-40 % of polyol polymer dispersion in anhydrous solvent (50 wt. %) was taken and wetting additive was added. This mixture was stirred for 15 minutes by using a crown disk stirrer with a help of overhead mechanical stirrer. Magnetic pigment, Fe(0)-Ni(0) 50:50, alloy 500 mesh powder having particle size of about 28 µm and less was added in 45-50 %. The Bohr magnetron measurement of this material shows a magnetic flux density of – 128.59 µT (Figure 6).After that co solvents and 0.3-0.7 wt % rheological additive and 0.05-0.3 wt % surfactant was added. This forms the base of the paint. Before application the paint was diluted by 5-10% and hardening agent was added if required and then sprayed on wooden, plastic and masonry surfaces. In general three coats of application shows satisfactory results.

Example 11: (FeCo 500#)
In a stainless steel vessel 30-40 % of polyol polymer dispersion in anhydrous solvent (50 wt %) was taken and wetting additive was added. This mixture was stirred for 15 minutes by using a crown disk stirrer with a help of overhead mechanical stirrer. Magnetic pigment, Fe(0)-Co(0) 50:50 alloy 500 mesh powder having particle size of about 28 µm was added in 45-50 %. The Bohr magnetron measurement of this material shows a magnetic flux density of – 168.74 µT (Figure 7). After that co-solvents and 0.3-0.7 wt % rheological additive and 0.05-0.3 wt % surfactant was added. This forms the base of the paint. Before application the paint was diluted by 5-10% and hardening agent was added if required and then sprayed on wooden, plastic and masonry surfaces. In general three coats of application shows satisfactory results.

Example 12:
An experiment was carried out using the lowest and highest magnetic strength pigment. Paint was prepared using PU binder as mentioned above in example 3 and 9. These paints were applied on a silicon release paper with increasingly 3 different (254, 508, 762 µm) wet film thickness. After drying the film was separated and magnetic measurement was performed. It was observed as the thickness of the film increases the magnetic power of the film also increases accordingly.
Example: 13:
In a stainless steel vessel 20 % of epoxy polymer dispersion in anhydrous solvent (75 wt%) was taken and wetting additive was added. This mixture was stirred for 15 minutes by using a crown disk stirrer with a help of overhead mechanical stirrer. Magnetic pigment, Cast Iron Fe (0) 350 mesh powder having average particle size of about 44 µmwas added in 68 %. The Bohr magnetron measurement of this material shows a magnetic flux density of – 156.73 µT (Figure 1). After that co mix xylene were added 5 % and 0.3-0.7 wt % rheological additive and 0.05-0.3 wt % surfactant was added. This forms the base of the paint. Before application the paint was diluted by 5-10% and hardening agent poly amide 4 % was added and then sprayed on wooden, plastic and masonry surfaces. In general three coats of application shows satisfactory results.
Example: 14:
In a stainless steel vessel 15 % of Alkyd dispersion in anhydrous solvent (75 wt %) was taken and wetting additive was added. This mixture was stirred for 15 minutes by using a crown disk stirrer with a help of overhead mechanical stirrer. Magnetic pigment, Cast Iron Fe (0) 350 mesh powder having particle size of about 44 µm was added in 65 %. The Bohr magnetron measurement of this material shows a magnetic flux density of – 156.73 µT (Figure 1). After that mineral turpentine oil were added 10 %. To this mixture Zirconium octoate, cobalt octoate and calcium octoeate was added as film forming agent. After 0.3-0.7 wt % rheological additive and 0.05-0.3 wt % surfactant was added. This forms the base of the paint. Before application the paint was diluted by 5-10% and then sprayed on wooden, plastic and masonry surfaces. In general three coats of application shows satisfactory results.

Example 15:

In a stainless steel vessel of 20-30 % polyol polymer dispersion in anhydrous solvent (50 wt %) was taken and wetting additive was added. This mixture was stirred for 15 minutes by using a crown disk stirrer with a help of overhead mechanical stirrer. Magnetic pigment, Cast Iron Fe (0) 350 mesh powder having average particle size of about 44 µm was added 40-50 %. Then magnetite having average particle size 3.5 µm were added 15-25%. After that co solvents were added before addition of 0.3-0.7 wt % rheological additive and 0.05-0.3 wt % surfactant. This forms the base of the paint. Before application the paint was diluted by 5-10% and hardening agent was added if required and then sprayed on wooden, plastic and masonry surfaces. In general three coats of application shows satisfactory results.
Thus composition increases the smoothness of the paint drastically, giving much higher gloss than sole addition of cast Iron Powder. This is attributed to better packing in the system without hampering overall magnetic performance of the film.

Example16: A preferred formulation in accordance with the present invention
Resin 15-25%
Dispersant 0.05 – 0.3 %
Solvent 4 – 6 %
Iron Powder (3.5 to 44 µm) 50 – 80 %
Zinc powder (optional) 5 – 8 %
Poly Urea (thickening agent) 0.3 – 1%
Hardener (If any) 4-7 %

Example17: A formulation not in accordance with the present invention

Resin 15-25%
Dispersant 0.05 – 0.3 %
Solvent 4 – 6 %
Iron Powder (3.5 to 44 µm) 45 wt%
Zinc powder (optional) 5 – 8 %
Poly Urea (thickening agent) 0.25 wt.%
Hardener (If any) 4-8 %

Example18: A formulation not in accordance with the present invention

Resin 15-25%
Dispersant 0.05 – 0.3 %
Solvent 4 – 6 %
Iron Powder (3.5 to 44 µm) 85 wt%
Zinc powder (optional) 5 – 8 %
Poly Urea (thickening agent) 1.1 wt.%
Hardener (If any) 4-9 %

For the above comparative formulations 17 and 18 not in accordance with the present invention, it was found that said magnetic paint formulations was not stable and settled after some time thus failing to generate a film with desired magnetic conservation characteristicsin spite of involving ferromagnetic particles of desired average particle size. In case of formulation 17 sagging and settling of the paint were observed whereas in case of formulation 18 gel was obtained which upon application forms very uneven surface with low magnetic property, and is difficult to spray. It was also found by way of the present invention that particle size above average particle size of 44 ?m resulted in much coarser coating resulting in a film thickness of more than 60 ?m which is not desired.
It is thus possible by way of the present advancement to provide for magnetic paint formulations based on a synergistic combination of ferromagnetic particles of desired particle sizes and compatible sagging and settling controlling rheology modifying thickener which when added in selective amounts control the oil absorption values of the magnetic pigments having net effect on the viscosity of the overall system having viscosity in the range of 80 poise to 30 poise at 25 ?C and possessing anti-sagging characteristics. It is noteworthy in case of example 4 above that the paint viscosity is raised so high it was not even flow able without dilution and hencethe viscosity has a huge role in stability, deposition and flow and levelling of the system which is selectively achieved by way of the present invention by addition of compatible rheological additives in selective amounts together with selective amount of magnetic pigments/ferromagnetic pigments. On the other hand in case of too dilute systems sagging of high density pigment and settling of the same was observed.