Pub. No.: WO/2017/214629 International Application No.: PCT/US2017/037052
Publication Date: 14.12.2017 International Filing Date: 12.06.2017
IPC:
C09D 5/23 (2006.01), G03G 9/107 (2006.01), G03G 9/113 (2006.01), G11B 5/702 (2006.01), G11B 5/708 (2006.01), G11B 5/842(2006.01)
Applicants: IDEAPAINT, INC. [US/US]; 40 Broad Street Boston, Massachusetts 02109 (US)
Inventors: MCLELLAN, Joe; (US).
HENNEK, John; (US).
WHITE, Mike; (US).
LI, Xinhua; (US).
DONBROSKY, JR., Martin; (US).
CLEMENT, Nelson; (US)
Agent: KAPLUN, Oleg, F.; (US).
FAY, Patrick J.; (US).
MARCIN, Michael J.; (US)
Priority Data:
62/348,539 10.06.2016 US
Title (EN) MAGNETIC PAINT COATINGS AND SURFACES
(FR) REVÊTEMENTS ET SURFACES DE PEINTURE MAGNÉTIQUE
Abstract: front page image

(EN)A light colored magnetic coating formulation (e.g., a paint formulation) having at least one solvent, at least one resin, and a plurality of ferromagnetic or magnetizable particles. The plurality of particles may have a mean particle size between 0.01 µm and 500 µm. The formulation is adapted to be applied onto a surface with a wet-film thickness of 0.2 mm and dried by evaporating the at least one solvent to form a film. The film may be of sufficiently light color to have a luminance of at least 60.
Magnetic Paint Coatings and Surfaces

Inventors: Joe McLellan, John Hennek, Mike White, Xinhua Li, Martin Donbrosky, Jr. and

Nelson Clement

PRIORITY CLAIM

This application claims priority to U.S. Provisional Patent Application Serial No.

62/348,539 filed June 10, 2016, the entire contents of which is hereby incorporated by reference herein.

TECHNICAL FIELD

This application relates to coatings for walls or other surfaces, which coatings have magnetic properties, products that include such coatings, and methods of making the same.

BACKGROUND

There are a number of paints and coatings available which serve decorative purposes, and others, such as dry-erase paints, which serve some functional purpose. For a few years, manufacturers have attempted to make paints and coatings mat also have magnetic properties, mainly by incorporating metallic particles into their paints. U. S. Patent Nos. 5,609,788 and 5,843,329 disclose using a magnetic paint additive made from certain ferromagnetic particles to impart magnetic properties. These currently available approaches typically suffer from a number of deficiencies. For example, they often require the application of a large number of coats to provide sufficient strength to hang materials from the wall, and they also result in paint with a grey hue that may be undesirable in many instances. In addition, these currently available approaches require development of specialized formulations to prevent oxidation of iron particles, prevent

magnetic materials from settling to the bottom of the paint can during storage, and allow for easy application of a smooth paint surface.

The coloring of current magnetic paints has been particularly problematic. These paints are made by mixing a typical paint formulation with a magnetizable material, like iron or iron oxide. With these paints, the color of the final paint/coating is dictated by the dark grey or black color of the magnetizable material. To compensate for the dark color of the magnetizable material, manufacturers and users of these paints typically tune the paint color by using a whitener/pi gment, such as titanium dioxide (TiO2) particles or organic whitening agents. Large quantities of these whitening agents are needed to compensate for the dark color of the magnetic materials. Since the amount of lightener affects the performance of the paint (e.g., ability to be applied by brush, roller, spray, etc.), the colors of resultant formulations are limited by the amount of lightener the formulation can tolerate. Thus, magnetic paint formulations are often limited to dark grey colors (or darker).

There is a demand for a paint or coating with magnetic properties, without the shortcomings of the current offerings.

SUMMARY

The present invention relates to a magnetic paint. The present invention also relates to light-colored magnetic paint. In one embodiment, the light-colored magnetic paint contains a plurality of magnetic particles made of: (a) a ferromagnetic or magnetizable core particle, (b) an adhesion promotion layer on the surface of the core particle, (c) high index of refraction, or reflective hiding layer, (d) a pigmented layer which may or may not be interspersed with the high index of refraction layer, and (e) a binding shell. In still another embodiment, the light-colored magnetic paint can be tinted to take on colors and shades within a wide range. The present invention also relates to a magnetic dry-erase system. It also relates to a kit for preparing a magnetic dry erase surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a first magnetic particle of the present invention.

DETAILED DESCRIPTION

A magnetic paint of the present invention is made by adding magnetic particles to a paint formulation. It will be understood by one of ordinary skill in the art that the magnetic particles described herein can be added to any existing paint formulations, including but not limited to those described in U.S. Patent No. 8,309,653, the contents of which are incorporated herein in their entirety. The magnetic particle can be added to any number of paints or primers, including but not limited to oil-based paints, water-based paints, latex paints, low-VOC paints, and the like.

In one embodiment of the magnetic paint of the present invention, the paint contains a plurality of magnetic particles made of: (a) a ferromagnetic or magnetizeable core particle, (b) an adhesion promotion layer on the surface of the core particle, a high index of refraction, or reflective hiding layer, (d) a pigmented layer which may or may not be interspersed with the high index of refraction layer, and (e) a binding shell.

Referring to FIG 1, a magnetic particle 1 of the present invention which is comprised a magnetic material 2 having a coating that is comprised of an adhesion layer 3, a high index of refraction or reflective hiding layer 4, a pigmented layer 5 that can tint or color the magnetic particle 1, and a binding shell 6 that ensures the layers are bound on the surface. It should be noted that, in the present application, the terms “magnetic” and “magnetizable” are used interchangeably. Here, the term magnetic encompasses both ferromagnetic materials (which have a net magnetic moment in the absence of an external magnetic field) and materials that are magnetizable, i.e. materials which increase the strength of an applied magnetic field, including paramagnetic, ferromagnetic, and superparamagnetic materials.

The magnetic particle 1 can be of a particle size ranging from 10 nm to >10 mm. The size can be optimized for a number of variables including but not limited to desired magnetic strength, and factors related to the consistency of the resulting magnetic paint. The particle size is preferably less than the desired coating thickness of the resultant magnetic paint. This limit is ~ 100 μm for most applications.

The magnetic material 2 can be comprised of metallic iron (Fe(0)), iron oxides Fe2O3, FeO), AINiCo, rare earth magnets such as neodymium magnets (NdFeB), metallic cobalt (Co(0)), metallic nickel (Ni(0)), SmCo (samarium cobalt), or similar materials, having a volume magnetic susceptibility greater than ~1 emu/cm3. The physical properties of the magnetic material, such as size, shape, and optical properties, as well as the composition of the material, including impurities, can be modified and optimized for the properties of the paint or coating formulation, such as the rheology, the tintability, and the magnetic strength.

The incorporation of the adhesion layer 3 is preferable to ensure good adherence of the high index of refraction hiding layer 4 to the surface of the magnetic material 2. This may include reactive materials (i.e., mercaptopropyltrimethoxysilane, tetraemoxysilane, tetramethoxysilane, aluminum trichloride, perhydropolysilazane, aminopropyltrimethoxysilane, titanium isopropoxide, zirconium isopropoxide, and the like), polymers (i.e., polyvinylpyrrolidone), poly(acrylic acid), carboxymethylcellulose, poly(styrenesulfonate), and the like), surfactants (i.e. PEG, polyPEG-PPG, CHAPS, SDS, Triton, and the like), and the like.

The high index of refraction or reflective hiding layer 4, can be comprised of a material that scatters or reflects visible light. It will be appreciated by one of ordinary skill in the art that these materials may include molecules, particles, or layers that are amorphous or crystalline, including but not limited to silver, gold, platinum, copper, aluminum, plasmonic nanoparticles, titanium dioxide, zirconium dioxide, zinc oxide, tin oxide, zinc sulfide, barium sulfate, or calcium carbonate. The purpose of the hiding layer 4 is to ensure that light does not interact with the magnetic core, and so will not be absorbed. The hiding layer 4 may scatter light efficiently, from particles with high index of refraction, or reflect light efficiently.

The pigmented layer 5 can be comprised of pigments or dyes commonly used in paints or colored coatings, including metal based pigments (cadmium yellow, chrome green, cobalt blue, cerulean blue, sanguine, oxide red, Prussian blue, zinc white, titanium white, titanium black, manganese violet, and the like), inorganic pigments (carbon black, raw sienna, burnt sienna, burnt umber, and the like), organic pigments (magenta, phthalo green, quinacridone, and the like), and the like. In some embodiments, this pigmented layer can be combined with the hiding layer.

The binding shell 6 may comprise of a polymeric material, (i.e. polyvinylpyrrolidone), poly(acrylic acid), carboxymethylcellulose, poly(styrenesulfonate), and the like), or a reactive material (i.e. titanium isopropoxide, zirconium isopropoxide, and the like). In some embodiments, the hiding layer 4 could be made of the same material as the pigmented layer S. In other embodiments, the pigmented layer S could be made of the same material as the binding shell 6. In further embodiments, the hiding layer 4, the pigmented layer S, and the binding shell 6 could all be made out of the same material.

The present invention also relates to a light-colored magnetic paint. In one embodiment, the light-colored magnetic paint contains a plurality of magnetic particles made of: (a) a magnetic or magnetizeable core particle, (b) an adhesion promotion layer or ‘primer’ on the surface of the core particle, and (c) a pigmented layer adhered to the exterior of the core particle.

In another embodiment, at least a portion of the magnetic particles are core-shell particles.

As appreciated by one knowledgeable in the art, the color properties of the paint formulations that can be achieved are largely determined by the components of the paint. As can be appreciated in the current invention, one such component in these formulations are the magnetic particles, and these must be taken into account. The luminance of a magnetic paint formulation without any tinting will then dominate the color that can be achieved. As a base formulation with a lower luminance value will have a limited number of colors that can be achieved, a base formulation with higher luminance can yield paints with a wider range of colors.

In one embodiment, the magnetic paint may be combined with a dry erasable coating to yield a magnetic dry erasable system. In another embodiment, the magnetic paint may be included as a part of a magnetic dry erasable kit, comprised of the magnetic paint, a white or colored paint, a dry erase system, a roller cover, and instructions for application. It should be known to those skilled in the art that a dry erase system or a dry erasable coating is one that yields a writeable-erasable surface that when marked with a marking material, such as a water- or alcohol-based marking material, the marking material can be erased to substantially invisible with little or no ghosting, even after prolonged and repeated use.

Method 1 of Producing Particles:

In one method of producing the magnetic particle of the present invention, the magnetic material is coated with a solution of the adhesion promotor, either in a polar or non-polar solvent (depending on the adhesion promoter). The magnetic material is then removed from solution using magnetic separation or filtration and purified to remove any excess adhesion promoter. The magnetic material is then re-dispersed into a solvent with a high index shell forming material, and the shell is grown on the surface of the magnetic particle. Following the growth of the high index of refraction shell, the particle can be coated with a binding shell that can act as a stabilization layer, which can also backfill any voids in the high index-of-refraction layer.

Method 2 of Producing Particles:

In another method of producing the magnetic particle of the present invention, the magnetic material is coated with a solution of the adhesion promotor, either in a polar or non-polar solvent (depending on the adhesion promoter). The magnetic material is then removed from solution using magnetic separation or filtration and purified to remove any excess adhesion promoter. The magnetic material is then re-dispersed into a solvent with a particulate material with a size smaller than that of the magnetic material, with a high index of refraction. These materials are stirred together, causing the particles to accumulate at the surface of the magnetic material. These coated magnetic particles can then be separated from the solution by magnetic filtration, or by filtration and washing. These coated particles can then be affixed to the surface through the use of a binding shell, which can be added directly to the particle solution, or to the washed particles. The binding shell is typically added from a non-aqueous solvent, however it can be added neat. Following the reaction of the binding shell, the light magnetic particles can be magnetically separated or filtered from the binder solution, washed several times, vacuum dried, and stored as a dry powder or dispersed in a coating formulation.

Quantitative Determination of Luminance of Magnetic Paint Surface (Uncoated Particles)

In this example, a paint with a range of uncoated magnetic particles were analyzed.

A photographic image of section of the paint was taken and processed using the ImageJ™ program to produce an average R-G-B value for each sample. The R-G-B value was then converted to luminance using the following formula: Luminance = (0.2126*R + 0.7152*G + 0.0722*B) The % Luminance = Luminance/255.

Addition of coated iron to paint

In this example, paint with a base of red, blue, or green was formulated with coated iron to determine the effect on the paint color. The tinted paint was treated with 20 to 50% coated iron, and mixed together. These magnetic paints were then placed on draw down cards, and drawn down with a 6 mil wet thickness to yield the samples below.

In this example, paint with a range of uncoated magnetic particles were analyzed.

A series of formulations were prepared each with 50% by weight of magnetic particles. The formulations were deposited on glass slides resulting in a constant volume coupons with a 1 inch diameter and 0.2 mm wet-film thicknesses. The formulations were allowed to dry. Using a ½ inch diameter and ¼ inch thick N52 NdFeB magnet, tensile tests were performed by bringing the magnet in to contact with the glass, of thickness 1 mm, on the opposite side from the coupons where the plane of the magnet and the plane of the glass are parallel, then measuring the attractive force between the magnet and the coupons in millipounds, i.e. the “lateral pull strength”, using a load cell. The average lateral pull strengths for these formulations shown in the graph below, were determined from measurements taken in triplicate for each sample.

Left: Formulations in acrylic based paint. Right: Formulations in epoxy based paint.

The coated magnetic particles shown here can be added to any number of paints or primers, including oil based paints, water based paints, latex paints, low-VOC paints, and the like primers to achieve a lightly colored formulation. Colored magnetic coatings can also be made by adding the coated magnetic particles to a colored paint or primer or by adding small volumes of colored pigments to a nearly white paint primer formulation including the coated magnetic particles

CLAIMS

What is claimed is:

1. A light colored magnetic coating formulation comprising:

at least one solvent;

at least one resin, and

a plurality of ferromagnetic or magnetizable particles, the plurality of particles having a mean particle size between 0.01 μηι and 500 μπι,

wherein the formulation is adapted to be applied onto a surface with a wet-film thickness of 0.2 mm and dried by evaporating the at least one solvent to form a film, the film having a luminance of at least 60.

2. The coating formulation of claim 1, wherein the film has a lateral pull strength of at least 100 millipounds.

3. The coating formulation of claim 1 , wherein at least a portion of the plurality of

ferromagnetic or magnetizable particles are each comprising:

a ferromagnetic or magnetizable core particle;

an adhesion promotion layer or a primer on a surface of the core particle;

a high index of refraction or reflective layer adhered to the adhesion promotion layer or the primer,

a pigmented layer adhered to the high index of refraction or reflective layer; and

a binding layer that adheres the pigmented layer.

4. The coating formulation of claim 1 , wherein at least a portion of the plurality of

ferromagnetic or magnetizable particles are core-shell particles each comprising:

a core where the core contains a plurality of ferromagnetic or magnetizable particles suspended in a medium, wherein the plurality of particles have a mean particle size between 0.001 μm and 500 μm, and wherein the plurality of particles are capable of individually reorienting its physical orientation in response to an electromagnetic field applied to the plurality of particles; and

a shell encapsulating the core.

The coating formulation of claim 1, wherein the film has a lateral pull strength from about 80 millipounds to about 300 millipounds.

The coating formulation of claim 1, wherein the formulation further comprises a further tinting agent to impart a tinting color, wherein the tinting color may be selected from a wide range of colors.

A magnetic dry-erase system, comprising the magnetic coating formulation of claim 1 used in combination with a dry-erase coating to yield a magnetic dry erasable surface.

A kit for preparing a magnetic dry-erase surface comprising a tintable magnetic primer or paint, a white or colored paint, a dry-erase formulation, a roller cover, instructions for use, and a container for the kit components.

A light colored magnetic coating formulation comprising:

at least one solvent;

at least one resin;

a plurality of ferromagnetic or magnetizable particles, the plurality of particles having a mean particle size from 0.01 μπι to 100 μm;

wherein the formulation is adapted to be applied onto a surface with a wet-film thickness of 0.2 mm and dried by evaporating the at least one solvent to form a film, the film having a luminance of at least 60, and a lateral pull strength of at least 100 millipounds.

10. The coating formulation of claim 9 further comprising one or more additives selected from the group consisting of: thickeners, pH modifiers, dispersants, antifoaming agents, pigments, coalescing agents, fillers, biocides, and viscosity modifiers.