U.S. patent application number 14/526079 was filed with the patent office on 2015-02-12 for method of forming a coating on a surface of a substrate.
The applicant listed for this patent is Innovatech, LLC. Invention is credited to Bruce Nesbitt.
Application Number | 20150044488 14/526079 |
Document ID | / |
Family ID | 32506366 |
Filed Date | 2015-02-12 |
United States Patent
Application |
20150044488 |
Kind Code |
A1 |
Nesbitt; Bruce |
February 12, 2015 |
METHOD OF FORMING A COATING ON A SURFACE OF A SUBSTRATE
Abstract
A reinforcing underlayment including dry uniform particles
evenly applied to a wet bonding material layer on a surface of a
substrate. The substrate, including the layers, is then cured to
harden the one or more of the layers. A final coating or topcoat is
applied to the cured surface of the substrate. The dry particles
are evenly distributed onto the bonding material layer creating a
uniform surface for subsequent coatings. The dry particles increase
the strength of the liquid coatings increasing solid particle
density within the coating system and thereby imparting properties
not available for the liquid coatings. The present invention
enables a user to easily introduce very heavy, dense, strong
particles into a liquid coating and allows the user to apply very
dense, heavy particles into and onto a wet bonding material layer
followed by a subsequent wet topcoat layer which is cured as one
contiguous material with reinforcement and underlayment
strengthening coming from the added, dry particles.
Inventors: |
Nesbitt; Bruce; (Chicago,
IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Innovatech, LLC |
Chicago |
IL |
US |
|
|
Family ID: |
32506366 |
Appl. No.: |
14/526079 |
Filed: |
October 28, 2014 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12904351 |
Oct 14, 2010 |
8895133 |
|
|
14526079 |
|
|
|
|
12612240 |
Nov 4, 2009 |
7838082 |
|
|
12904351 |
|
|
|
|
11844708 |
Aug 24, 2007 |
7618684 |
|
|
12612240 |
|
|
|
|
11157001 |
Jun 20, 2005 |
7261925 |
|
|
11844708 |
|
|
|
|
10318503 |
Dec 12, 2002 |
|
|
|
11157001 |
|
|
|
|
Current U.S.
Class: |
428/474.4 |
Current CPC
Class: |
A47J 36/025 20130101;
B05D 5/00 20130101; B05D 7/52 20130101; A61B 2018/0013 20130101;
A61L 2300/104 20130101; B05D 7/54 20130101; A61L 31/16 20130101;
C03B 35/14 20130101; B05D 3/0281 20130101; Y10T 428/2438 20150115;
B05D 5/02 20130101; Y10T 428/24413 20150115; B05D 2601/20 20130101;
A61B 18/1402 20130101; B05D 5/083 20130101; Y10T 428/24372
20150115; A61L 2420/02 20130101; A61L 2420/08 20130101; A61B 18/14
20130101; B05D 5/08 20130101; B65G 49/064 20130101; A61L 2300/404
20130101; F16C 33/201 20130101; B05D 5/06 20130101; A61B 2018/00148
20130101; B05D 3/20 20130101; A61L 31/10 20130101; Y10T 428/254
20150115; Y10T 428/31725 20150401; Y10T 428/32 20150115; B65G
2249/02 20130101 |
Class at
Publication: |
428/474.4 |
International
Class: |
A47J 36/02 20060101
A47J036/02 |
Claims
1. A coated substrate comprising: a substrate; a non-stick bonding
material secured to a surface of the substrate; a layer of aramid
fibers secured to the non-stick bonding material, at least a first
portion of a plurality of the aramid fibers each being partially
submerged within the non-stick bonding material and at least a
second portion of each of said plurality of aramid fibers
protruding from the non-stick bonding material; and a top coating
secured to the bonding material.
2. The coated substrate of claim 1, wherein the substrate is
selected from the group consisting of: a cooking device, a food
processing device, and a food conveyor.
3. The coated substrate of claim 1, wherein the layer of aramid
fibers includes at least two different sized aramid fibers.
4. The coated substrate of claim 1, wherein the aramid fibers are
ground.
5. A coated substrate comprising: a substrate; a bonding material
secured to a surface of the substrate; a single layer of aramid
fibers secured to a top of the bonding material; and a top coating
secured to the single layer of aramid fibers.
6. The coated substrate of claim 5, wherein the substrate is
selected from the group consisting of: a cooking device, a food
processing device, and a food conveyor.
7. The coated substrate of claim 5, wherein the single layer of
aramid fibers includes at least two different sized aramid
fibers.
8. The coated substrate of claim 5, wherein the aramid fibers are
ground.
9. The coated substrate of claim 5, wherein the bonding material is
a non-stick bonding material.
10. A coated substrate comprising: a substrate; a non-stick bonding
material secured to a surface of the substrate; and a plurality of
aramid fibers in the non-stick bonding material.
11. The coated substrate of claim 10, wherein the substrate is
selected from the group consisting of: a cooking device, a food
processing device, and a food conveyor.
12. The coated substrate of claim 10, wherein the plurality of
aramid fibers includes at least two different sized aramid
fibers.
13. The coated substrate of claim 10, wherein the plurality of
aramid fibers are ground.
14. The coated substrate of claim 10, which includes a top coating
secured to the bonding material.
Description
PRIORITY CLAIM
[0001] This application is a continuation of, claims priority to
and the benefit of U.S. patent application Ser. No. 12/904,351,
filed on Oct. 14, 2010, which is a continuation of, claims priority
to and the benefit of U.S. patent application Ser. No. 12/612,240,
filed on Nov. 4, 2009, now U.S. Pat. No. 7,838,082, which is a
continuation of, claims priority to and the benefit of U.S. patent
application Ser. No. 11/844,708, filed on Aug. 24, 2007, now U.S.
Pat. No. 7,618,684, which is a continuation of, claims priority to
and the benefit of U.S. patent application Ser. No. 11/157,001,
filed on Jun. 20, 2005, now U.S. Pat. No. 7,261,925, which is a
continuation of, claims priority to and the benefit of U.S. patent
application Ser. No. 10/318,503, filed on Dec. 12, 2002, the entire
contents of which are each incorporated by reference herein.
BACKGROUND
[0002] Coatings on parts and products are used in industry for
several different purposes. Certain coatings, for instance, are
applied to surfaces to provide low friction, non-stick, abrasion
resistant or other specific properties. When a harder object
contacts a surface and friction is created, the friction of the
force on the surface wears away a portion of that surface. Over
time, the cumulative effect of repetitive or continuous contact
between the object and the surface causes a substantial portion of
the surface to wear away so that the surface is no longer
functional. One example of such an object applying such a force is
the force applied between metal cooking utensils (i.e., the
objects) and cooking surfaces such as the non-stick coatings
applied to surfaces of pots or pans. Continuous contact between the
utensils and these cooking surfaces causes the coatings applied to
the surfaces, such as non-stick coatings, to gradually wear away
and diminish the effectiveness of the coatings. Therefore,
manufacturers have developed abrasion-resistant, non-stick coatings
incorporating harder and more durable particles, which resist the
abrasive forces created by cooking utensils as the utensils contact
the coated surface of the cooking surfaces. As a result, these
coatings enhance the durability of cooking surfaces, however, the
coatings compromise the non-stick properties of the surface. In
addition, the introduced hard particles are not attached firmly to
the surface to provide rigid support of the relatively soft
non-stick material topcoat. The loose particles can therefore,
dislodge from the surface relatively easily.
[0003] Wear also occurs, for example, when a surface or surfaces of
a component are subject to continuous and prolonged forces such as
rotational or reciprocating forces applied by a first object which
basically, rubs against the surface of a second object, creating
friction between the objects. The friction generally wears away one
or both of the surfaces. If one surface is sacrificial in nature,
commonly including softer particles or materials versus harder
particles or materials, it will wear sooner than the surface
including the harder, more durable surface. To prevent this,
coatings, which are comprised of relatively soft materials, are
applied to a part or parts so that the parts can be replaced easily
when the coating wears out. An example is a PTFE-coated solenoid
plunger inside a housing of a solenoid which must remain dry or
without fluid lubrication in use. In operation, the PTFE-coated
solenoid plunger wears at a predictable rate due to friction
created between the surface of the plunger and the surface of the
housing. Therefore, the plunger can be exchanged for a newly coated
plunger on a predictable maintenance schedule. This is particularly
appropriate when no fluid lubricants can be introduced into a
system.
[0004] Another example of intended sacrificial wear is a wear end
plate in a rotary gear pump. A thin layer of bronze is attached to,
for example, a replaceable iron plate. This plate can be changed
when the bronze layer wears.
[0005] Other methods of applying reinforcing coatings to surfaces
to provide wear resistance for soft coatings have been developed.
In another example, metal spray coatings, such as bronze, are arc
sprayed or flame sprayed onto metal parts to produce an
intermittent bronze coating, which is subsequently coated with PTFE
and finished into a smooth surface. The wear resistance of the
bronze particles reinforce the relatively weak strength of the
PTFE, which has a very low friction however with low wear
resistance. This bronze/PTFE coating system will wear longer than a
unreinforced PTFE coating.
[0006] Coatings are also used for many applications such as for
rust resistance, corrosion resistance and as functional or
protective coatings. In one example, plastic electric motor brush
covers are coated with coatings containing metal to absorb and
conduct electrical emissions to reduce electrical emissions coming
from electric fuel pumps in an automobile or other vehicle.
[0007] Coatings may be applied in various different known manners.
One method of applying the coatings is to spray the coatings on to
a substrate such as metallic material. The coatings are usually
sprayed so that the coatings completely cover the surface or
surfaces of the substrate that require the coating. Typically, a
bonding agent such as primer is used to initially coat the
substrate to promote the adhesion of the coating to the substrate.
The bonding agent or primer is typically applied to a cleaned
surface of the substrate. Additionally it has been known to add
particles to the liquid primer and/or the base coating to increase
the abrasion resistance of the liquid coating and primer. As a
result, the coating or coatings applied to the substrate has
greater abrasion resistance.
[0008] In one known coating process described in U.S. Pat. No.
5,492,769, hard particles are embedded in a surface layer on a
substrate to improve the scratch or surface wear resistance of the
substrate. The surface of the substrate is prepared and then a thin
layer of discrete, hard particles are applied to the surface of the
substrate. The surface of the substrate is then softened using heat
or a solvent. The surface may also be softened prior to the
application of the particles to the surface if needed. After the
surface of the substrate is softened, the particles are embedded
into the softened surface of the substrate using pressure. The
particles are embedded in the surface so that approximately 50% of
the volume of the particles are located at the surface layer. The
softened surface is then allowed to re-harden, which embeds and
bonds the particles to the surface of the substrate. This bonding
method is generally limited to substrates such as plastics,
polymers and softer metals, which are relatively softer than the
particles being embedded in the surfaces of these substrates.
[0009] In another known coating process, solid particles are mixed
with a liquid primer prior to applying the primer to the surface of
the substrate. The particles are non-uniform or irregular in shape
and the particles are also non-uniformly dispersed or mixed within
the primer because the distribution of the particles cannot be
controlled. Therefore, as the primer mixture is applied to the
surface of the substrate, the unevenly distributed particles within
the primer tend to pool or bunch up on particular areas of the
substrate, particularly if the particles are very heavy. In
addition, heavy introduced particles in a liquid coating system,
will settle in different densities on horizontal, vertical or other
pockets or depressions of a coated part. As a result, certain
portions of the substrate include more particles than other
portions of the substrate. This creates an uneven or non-uniform
distribution of introduced particles on the substrate that has been
coated. Thus, when a topcoat or final coat that contains heavy or
dense particles is applied to the substrate, the topcoat or final
coat also pools or builds up in the same areas on the substrate as
the particles in the primer mixture. This diminishes the finish
strength or quality of the surface of the finished product.
[0010] In a further known coating process, the particles are flame
sprayed or applied in a molten droplet form and propelled onto the
surface of the substrate. The molten particles adhere to the
surface of the substrate. However, the molten particles are
typically applied or sprayed onto the substrate at such a rate that
the molten particles flatten or partially flatten as the particles
hit or contact the surface of the substrate. Thus, the surface of
such substrates are often uneven because of the varying shapes of
the applied molten particles. As described above, this causes an
uneven surface area or non-uniform surface area so that the coating
that is subsequently applied to the particles is also uneven and
non-uniform.
[0011] One known wear resistant coating sold under the trademark
Excalibur.RTM. by Whitford Worldwide is formed using molten
stainless steel particles and provides non-stick and initial low
friction characteristics to surfaces of substrates but is limited
in its application exclusively to metal substrates. This coating is
applied to a substrate surface by first grit blasting the surface
with a suitable abrasive to roughen it and promote the adherence of
subsequent material layers. Then, stainless alloy particles are
electric-arc sprayed onto the roughened metal surface of the
substrate. The particles cool and harden forming varying surface
configurations including high peaks and low peaks, which do not
completely bond to the surface. Next, several layers of
fluropolymer coatings are applied to the particle layer and
permanently bond all of the coatings in place on the surface of the
substrate. The application of the molten particles, however, incurs
the same problems as described above. Thus, the distribution of the
size and shape of the molten particles in this process are
generally not uniform or evenly distributed on the surface of the
substrate.
[0012] The varying particle shapes in the above processes and
coatings affect the uniform distribution of the particles on the
surface of the substrate. The particles are applied to the surface
of the substrate to increase the abrasion resistance of the
subsequently applied coating. The irregularly shaped particles
generally are not evenly or uniformly distributed on the surface of
the substrate because the irregular surfaces of the particles
generally do not correspond with each other. In addition, particle
size may vary where some particles are much larger than other
particles. Thus, some particles bunch together while other
particles are spread apart based on the size and shape of the
particles. This causes the particles to be non-uniformly
distributed and be of non-uniform size on the surface of the
substrate, which in turn, causes the coating applied to the
particles to be non-uniform.
[0013] Furthermore, the irregular shape of the particles limits the
consistency of the surface area created by the addition of the
non-uniform particles to the substrate. As described above,
irregularly shaped particles may bunch up or be spread apart on a
percentage of the surface of the substrate and consist of varying
heights. Therefore, the maximum surface area of each particle may
not be exposed to prevent coating wear depending on whether the
particles are partially or wholly covered by other particles and
whether particles, such as molten metal particles, are deposited on
top of previously deposited particles. Because the maximum
exposable surface area of each particle is not consistently
available, the total surface area generated by the addition of the
particles to the substrate is limited or diminished. As a result,
the bond between the coating and the particles is less consistent
and weaker than if the maximum exposable surface area is exposed
for coating by subsequent topcoats. This results in loose or
non-adherent particles on top of the previously deposited
particles.
[0014] Another reinforced metal/PTFE coating system consists of an
electric arc spray of stainless steel or titanium particles
subsequently coated with a two coat PTFE commercial non-stick
coating. In one example, an aluminum cooking pan is grit blasted
with aluminum oxide to roughen the aluminum surface to assist the
mechanical attachment of the dissimilar metal stainless steel or
titanium particles to the pan. The stainless steel particles are
heated to provide molten stainless steel particles which are
propelled toward the grit blasted surface. The deposited molten
stainless steel or titanium particles cool and the result is a
rough, varied group of various shaped metal particles which are
mechanically attached to the rough grit blasted aluminum surface.
This irregular surface, which resembles a mountain range of
irregular shaped stainless steel particles, is then coated with two
or more coatings of a commercial non-stick coating. When cooking
utensils contact the reinforced non-stick coating, wear is reduced
as the metal particles take the mechanical abrasion created by
cooking utensils.
[0015] This stainless steel/PTFE coating system is exemplified by
the Whitford Corporation's Excalibur.RTM. coating system. After the
stainless particles are deposited on the aluminum, the
Excalibur.RTM. coating system includes the steps of removing
non-adherent particles of loose stainless steel from the aluminum.
The loose, non-adherent or slightly adherent particles of stainless
steel are removed by wire brushing, air cleaning or both prior to
the application of the topcoats of PTFE based non-stick
coatings.
[0016] Uneven or non-uniform distribution of a coating on a surface
of a substrate causes several different problems or issues for
manufacturers. An uneven coating on the surface of a particular
part will cause uneven wear of the parts and subject the part to
more friction if particles protrude through the final coating or
topcoat. Conversely, if there are less reinforcing particles in an
applied coating due to the non-uniform distribution of the
reinforcing particles in the coating on the surface of the part,
the coated surface of the part will have less wear resistance or
wear protection. Thus, the greater friction and wear on the part
may cause the part to fail during operation or not last as long in
operation. Additionally, an uneven coating quality may cause a part
to not perform as well in operation. An uneven surface roughness
due to uneven internally distributed and dispersed reinforcing
particles may also cause a part or parts requiring specific
tolerance levels or dimensions to be outside acceptable limits and
therefore not meet desired designed specifications, fail during
assembly or during operation. If the coating over the irregular
stainless particles is designed to provide non-stick or release
properties, taller or larger stacked particles protruding through
the coating quickly wear, dislodge easily and diminish the desired
non-stick or release properties and cause sticking instead of
preventing it.
[0017] In a mechanical wear situation, if the dispersed
lubricant/reinforcing materials within the liquid coating, whether
the materials are metal or non-metallic materials, are protruding,
mechanical interference may be caused thereby preventing component
motion. If the particles are not dispersed uniformly, the wear
resistance and consistency of performance is diminished.
[0018] Additionally, liquid coating end use requirements for
reinforcing a coating on a surface of a substrate to provide
augmentation of, for instance, a soft coating to increase the wear
resistance is presently accomplished by introducing hard particles
to the liquid coating. The desired laminar placement of specific
particles in the coating is impossible when particles are dispersed
in a liquid coating. The placement of reinforcing particles within
a coating in a specific area is not possible with a liquid coating
containing dispersed particles. Furthermore, the placement of
different wear resistant particles in a specific order or location
with different properties cannot be done in a liquid coating
application. Also, providing an extremely dense, near 100% dense
layer of reinforcing particles under a smooth topcoat is not
possible with a liquid coating. Even if multiple layers are
applied, the possibility of particles moving and migrating in a
liquid coating prevent assurance of and determination of density
before subsequent coating layers are applied as the liquid carrier
reduces the density of the interconnected particles. Additionally,
if a liquid coating application includes heavy, hard particles such
as certain abrasive particles, the coating is difficult to apply
using conventional pumps and spray guns, which causes the pumps and
spray guns to wear more rapidly.
[0019] Accordingly, there is a need for a coating method, and
specifically a coating reinforcing underlayment and method of
manufacturing same which enables a reinforced coating system to be
evenly, uniformly and densely applied to the surface of a
substrate.
SUMMARY
[0020] The present invention relates in general to coated
substrates, and specifically to a coating reinforcing underlayment
for coating substrates on which a topcoat such as PTFE, will be
applied and a method of manufacturing the coating reinforcing
underlayment.
[0021] One embodiment of the coating reinforcing underlayment of
the present invention is applied to a substrate, which may be any
suitable substrate, and which includes a layer of a wet bonding
material applied to the surface of the substrate to be coated and a
single layer of substantially uniform dry particles applied
directly into and to the wet bonding material layer. In another
embodiment, the above process is repeated until a desired thickness
is achieved or until a specific number of layers are applied to the
surface of the substrate.
[0022] In one presently preferred embodiment of the method of the
present invention, a substrate is positioned on a support so that a
surface or surfaces of the substrate may be coated. Initially, the
surface of the substrate is cleaned with a cleaner to remove
impurities which may be present on the surface of the substrate.
The cleaner such as a solvent may be manually applied or
mechanically applied to the substrate. In one embodiment, grit
blasting or sandblasting is used to clean the surface of the
substrate. Alternatively, the substrate may be pre-cleaned or the
method may be performed in a "clean room" where the cleaned part is
manufactured and the step is not necessary.
[0023] Once the surface of the substrate is cleaned, a layer of a
wet bonding material such as a primer is applied to the surface of
the substrate. The wet bonding material may include one or more
additives which change or enhance one or more characteristics of
the wet bonding material. For example, in one embodiment, the wet
bonding material includes an ultraviolet light cure resin. In
another embodiment, the wet bonding material includes an electron
beam cure resin. It should also be appreciated that the bonding
material may be any suitable bonding material or agent. The bonding
material layer is formulated to also improve the bonding
capabilities of the subsequent coating layer or layers applied to
the surface of the substrate in addition to retaining the
particles. The layer of wet bonding material is preferably applied
uniformly so as to avoid forming a thick layer, which is thicker
than what is necessary or required, and avoid drippings which may
detract from the bonding ability to the substrate.
[0024] In one embodiment, while the bonding material layer is still
wet, a single layer of substantially uniform dry particles such as
a powdered engineering plastic, dry metal particles, dry ceramic
particles or pre-coated or micronized dry particles are sprayed
over the wet bonding material. The powdered or dried particles
adhere to the wet surface area of the bonding material in an even
manner. In this embodiment, when the wet bonding material is
completely coated with one layer of the uniform powdered particles,
additional dry particles cannot stick to the bonding material layer
because the adhered particles attached to the bonding material
layer act as a barrier to other particles attaching to the wet
bonding material layer. Therefore, the dry particles do not build
up or form an uneven surface area on the surface of the substrate.
Additionally, the wet bonding material layer may be a thick layer
where the uniform particles sink into and are completely covered by
the wet bonding material layer. In another embodiment, the wet
bonding material layer is a substantially thin layer on the surface
of the substrate and a substantial portion of the particles are
exposed on the wet bonding material layer. Once applied, the dry
particles substantially increase the surface area of the
substrate.
[0025] The substantially uniform dry particles are preferably
consistent or include particles that have substantially consistent
granular size and shape. In one embodiment, the particles are
substantially round in shape. It should be appreciated that any
suitable size or shaped particles may be employed in the present
method such as flat-shaped, flake-shaped, cylindrical-shaped,
oblong-shaped or leaf-shaped particles to suit the end use of the
part being coated with this process. In one embodiment, the dry
particle sizes and shapes are determined based on the end use and
desired specifications and chemical composition of the coated
substrate.
[0026] In one example, angular particles such as triangular shaped
particles or similar particles are used to create a rough surface
on a substrate by applying the angular particles to the bonding
material layer on the surface of the substrate. In another example,
less abrasive and lower friction surfaces are created by using
shaped particles such as spherical or round shaped particles. In a
further example, one or more combinations of different shaped
uniform particles are used on a surface of a substrate. Thus,
uniformly sized or shaped groups of uniform particles or different
sized or shaped particles may be applied to a surface of a
substrate. The wet bonding material layer and the substantially
uniform dry particle layer are applied to the surface of the
substrate until a desired thickness is achieved. Any suitable
thickness ranges may be used as desired and determined by the
manufacturer. Additionally, the density of the particles may vary
depending on the design specifications of an end product or final
product. The density or distribution of the particles may vary from
covering or adhering to approximately ten percent of the surface of
the substrate to approximately one hundred percent of the surface.
Similarly, the density of the uniform particles may vary depending
on the end use criteria.
[0027] In another embodiment, low friction uniform particles are
applied to a lower layer followed by another very thin outer or
upper layer of very fine abrasive particles. This system initially
micro-abrades and smoothes out a counterface or counter surface of
relatively rough metal which the coating wears against until the
abrasive layer is worn down. After the thin abrasive layer is worn,
the underlying layer of non abrasive friction reducing particles
provides low friction to the now smooth counterface or opposing
surface. This embodiment may for instance be used in shock
absorbers where a low quality relatively rough metal internal
surface of tubing is wearing against a coated piston.
[0028] The types of coatings and/or uniform particles applied to a
substrate may be any suitable type of particle as generally as
indicate above. In one embodiment, whisker or rod shaped particles
such as carbon fibers or carbon whiskers or nickel whiskers are
applied to a surface of a substrate to reduce wear on the surface
and provide a non-metallic or metallic conductive surface for
industries where electrically conductivity is an issue or a
requirement. In another embodiment, aramid fibers or engineered
plastic particles or fibers are applied to a substrate to
strengthen the surface of the substrate. The aramid fibers include
Kevlar.RTM. or Nomex.RTM. fibers which are introduced in
substantially the same manner as the carbon fibers or whiskers. The
Kevlar.RTM. or Nomex.RTM. fibers or materials can be either a pulp,
which includes loose, fluffy fibers which is further ground into
fibrillated fine powder, or can be other suitable forms such as
round particles or semi-round dry particles. The aramid particles
provide non-metallic wear resistance and have good bonding ability
with both the basecoat and subsequent topcoats. Thus, the applied
aramid fibers or materials create a dense layer of aramid or
Kevlar.RTM. particles on the surface of the substrate, which is
then coated with a topcoat or other suitable final coating.
However, if a very high temperature, moderate friction (i.e., low
abrasion) surface is desired, a topcoat or final coating is not
applied to the layer of aramid fibers. In another embodiment,
diamond particles are applied to the wet bonding material layer.
Although this option has a much greater cost than other particles,
the diamond particles provide greater wear resistance and less
friction on the surface. These particles add tribological benefits
beyond those benefits of aramid fibers.
[0029] In another embodiment, specially treated, uniform plastic
particles are applied to a surface of a substrate. The plastic
particles can be pre-treated PTFE, ultra high molecular weight
polyethylene (UHMW) and/or PE or another suitable material are
applied to the wet bonding material on the surface of the
substrate. The particles are irradiated or processed with an
electron beam which causes changes to the surface of the particles,
allowing them to wet more easily and to sink into the wet bonding
material layer, instead of remaining on the top of the material
bonding layer. Therefore, the plastic particles are strongly bonded
to the layer and not easily dislodged from the surface. This
process thereby enables the plastic particle layer to last
longer.
[0030] In another alternate embodiment, anti-microbial particles
such as silver or silver compounds are applied to the surface of a
substrate to reduce and kill bacteria and other potential germs
that may be located on a surface of a substrate such as a kitchen
counter or a food storage vessel, container or a conveyor or hook
in a meat packing facility. In this embodiment, a dense layer of
anti-microbial material in a powder or particulate form is applied
to the wet bonding material layer. In one aspect of this
embodiment, the anti-microbial particle layer is the final layer.
In another aspect, a thin topcoat or final coating is applied to
the anti-microbial particle layer to provide a release or non-stick
surface on the substrate. The above process can be repeated as
necessary to maintain the effectiveness of the anti-microbial
surface. In this aspect, the thin topcoat or topcoats do not
completely cover the protruding anti-microbial particles.
[0031] In another embodiment, dry or powdered, ultra porous bronze
particles are applied to the wet bonding material layer on the
surface of a substrate. The ultra porous bronze particles include
many openings and voids so that the particles are approximately
seventy percent solid compared to over ninety percent solid for
most porous bronze materials. The particles enable a user to infuse
the very porous bronze particles with the wet bonding material
after the bronze particles are deposited on the wet bonding
material on a surface of a substrate. This method is used to add
lubrication and "lock" or strongly secure the particles into the
liquid bonding material layer to increase the bonding strength of
the layers to hold the bronze particles to both the upper and lower
coating layers on the surface of the substrate even after being
exposed to abrasive forces. The particles may be any suitable
porous metal particles such as stainless steel particles, nickel
particles, bronze particles, iron particles, titanium particles or
other suitable particles including a metal and/or metal alloys.
[0032] In another embodiment, porous metal particles such as the
bronze particles described above are impregnated or infused with a
material such as PTFE, which lowers the friction of the particles.
In one aspect of this embodiment, bronze particles or any other
suitable metal particles including approximately seventy percent
voids (i.e., air) are vacuum impregnated with a suitable lower
friction material such as PTFE. In another aspect of this
embodiment, the bronze particles are soaked with the PTFE and then
dried. The latter process leaves partial voids in the bronze
particles. However, the particles are partially infused with PTFE,
which adds low friction capabilities to the bronze.
[0033] In a further embodiment, catalyzed resins consisting of two
parts or plural components such as epoxies or urethanes are used to
coat a surface of a substrate. In one example, these catalyzed
bonding agents are used to coat a substrate such as a plastic or
low temperature metal to enhance the wear resistance of the surface
of the plastic or metal while not affecting the strength of the
plastic or metal.
[0034] In another embodiment, acid or chemical resistance is
increased by applying non-metallic, non-plastic particles such as
substantially uniform dry ceramic or mica flakes and/or mica
particles to the wet bonding material layer. Other suitable
particles may be used such as glass, ceramics, modified mica, boron
nitride, silicon nitride and aluminum oxide particles. The dry
ceramic or mica flakes and/or particles create a barrier or a
substantial barrier to an acid or other chemical. The barrier
created by the particles or flakes diverts the acid or chemical
from directly attacking a base material such as a metal, by
decreasing the inherent permeability and porosity of a base coating
or coatings on the surface of a substrate. A torturous, indirect
path or maze-like path chemicals must take to reach the underlying
surface is created by the plates or flakes so that the chemical or
acid is forced to take an indirect path around the mica particles
or flakes thereby slowing and/or retarding the speed and dynamics
of the chemical or acid that is trying to permeate the coating.
[0035] Once the plural component resin followed by dry particles
are applied to the surface of the substrate, the bonding material
and substantially uniform dry particle layer are cured by catalytic
cure, by heating the layers, air-drying the layers or according to
any suitable curing method. The curing process cures the resin or
dry particles so that a strong bond develops between the
substantially uniform dry particle layer and the wet bonding
material layer as it hardens and also bonds to the base surface.
Because the dry uniform particles were applied to the wet bonding
material, the particles are tightly packed and form a single
uniform, substantially even surface on the substrate. As a result,
the substantially uniform dry particles increase the surface area
on the substrate and enable a topcoat to be applied uniformly and
evenly on the substrate. Additionally, the topcoat develops a
strong bond with the dry particles below which is bonded to the
substrate. This process may be repeated one or more times to
increase the total thickness and chemical resistance of the
coatings on the surface of the substrate.
[0036] In another embodiment, a wet bonding material layer
including relatively small particles of a suitable low friction or
soft material is first applied to the surface of a substrate. Next,
a layer of uniform hard dry particles or other suitable hard
particles is applied to the wet bonding material layer. Another
layer of the initial wet bonding material mixture including the
relatively smaller particles is then applied to the dry particle
layer. The layers are dried using a suitable drying or curing
process, which causes the top layer or second wet bonding material
layer including the small soft particles to shrink and distribute
the small soft particles amongst the hard particles. This creates
an abrasion resistant and low friction surface.
[0037] The spraying or application of the dry particles to the wet
bonding material layer on the surface of the substrate may be
adjusted to enhance the strength of the bond between the bonding
material and the dry particles and the density of the layers on the
substrate. In one embodiment, the pressure of the dry particle
spray and the rate of the spray is increased to increase the
density of the particles in the material bonding layer. The greater
the density of the particles and depth of the layers, the greater
the strength and desired characteristics of the resultant coated
substrate.
[0038] In another embodiment, an electrostatic, tribo-charged or
opposite electrostatic charged powder spray method is used to apply
the dry particles to the wet bonding material. The charged particle
powder spray enables an operator to better control the application
uniformity of the dry particles and thereby enhance the density and
application of the dry particles to the wet bonding material on the
substrate. In a further embodiment, the electrostatic powder spray
is used to apply a topcoat over the dry particles such as a powder
paint coating or fluoronated plastic powder coating to the surface
of the substrate. In this embodiment, a bonding material and then a
conductive material or thin conductivity enhancing coating is
applied to the surface of the substrate. The powder topcoat or
final coating is then cured in a convection or infrared oven, which
heats and shrinks the powder coating onto the top of the dry
particles.
[0039] In another embodiment, an applicator such as a sifter is
used to uniformly apply the uniform particles to the wet bonding
material layer. The sifter is similar to a conventional flour
sifter and is used in certain applications depending on the size of
the uniform particles.
[0040] In a further embodiment, ferromagnetic or magnetic dry
particles are applied to a surface of a substrate to completely
coat a surface of a substrate or form a shape, symbol, character or
other suitable image on a surface of a substrate. Initially, a
non-magnetic metal surface or glass surface or aluminum surface is
coated with a wet bonding material. Magnetic particles such as
special magnetic stainless steel, magnetic ferrite or ferrous
particles are applied to the wet bonding material. These magnetic
particles are attracted to the magnetic shape or symbol lying
directly under the wet coated glass, aluminum or non-magnetic
substrate, thereby creating a design in the finished coating.
[0041] In another embodiment, a surface or a portion of a surface
of a substrate such as the surface of a part is masked or
selectively coated with a suitable masking device or material so
that the dry uniform particles can only be applied to the unmasked
areas on the surface of the substrate. In this embodiment, the wet
bonding material is generally applied to the entire surface or
surfaces of the substrate and then a masking material or device is
applied to a specific area or areas on the surface of the
substrate. However, the wet bonding material layer can be applied
to a pre-masked substrate to coat the selective areas of the
substrate. Therefore, the dry uniform particles, which are
subsequently applied to the surface of the substrate, adhere to the
exposed portions of the wet bonding material layer but not the
masked portions of the surface of the substrate.
[0042] The coating layer applied to the underlayment or wet layer
and the dry second layer may be any suitable coating such as a
topcoat layer. It should be appreciated that the method of
manufacturing or forming the coating underlayment may be performed
as described above by applying or spraying the coatings onto the
surface of the substrate. Alternatively, the coatings and dry
particles may be applied using other suitable coating and
application methods. In one embodiment, the wet bonding material
layer is applied by dipping the substrate either completely or
partially in the wet bonding material layer.
[0043] Several different types of additives may be added to the
topcoat or final coating to improve the performance characteristics
of the coated substrate. In one embodiment, a counter face
smoothening additive including relatively hard particles, is added
to a topcoat or final coat, in either a liquid or dry powder form,
to enable the coated substrate to smoothen or polish a rough
surface or surfaces, which contact the surface of the coated
substrate. It should be appreciated that any suitable additive may
be added to the topcoat or final coating to improve the performance
or desired characteristics of the coated substrate.
[0044] In another embodiment, the substrate previously coated with
a wet bonding material layer and dry particle layer, may be
electrostatically charged to attract the uniform dry particles
having an opposite charge. In this embodiment, substantially
uniform dry powder particles are electrostatically attracted to the
substrate because the particles have an opposite charge to the
surface of the substrate. In one example, a powder paint coating
such as an epoxy or polyester is applied to a surface of a
substrate. In this example, a liquid layer is applied to a surface
of a substrate and then an electrically conductive dry particle
material layer is applied to the surface. The powder coating is
then applied and is electrostatically attracted to the conductive
material outer layer. Because the powder coating does not include
solvent, the coatings are cured in a convection or infrared oven
even though the lower layer of the basecoat contains specific
solvents. The solvents in the basecoat migrate through the dry
powder before the top powder coat starts to jell and cure into a
continuous coating. The powder coating heats up and shrinks over
the top of the dry particle layer forming a uniform, evenly
distributed topcoat layer on the surface of the dry particle
layer.
[0045] Alternatively, non-electrical, tribo-charged dry paint
topcoat particles can be applied to a grounded part. In this
embodiment, a very thin wet layer remains wet while the powder coat
is applied either electrostatically or via a tribo-charge (i.e.,
friction charge). The entire coated part is oven cured to
simultaneously cure the wet and dry powder topcoats.
[0046] In another embodiment, the substantially uniform aluminum
oxide particles are applied to a wet bonding layer surface of a
substrate to achieve a desired roughness on the surface. The
desired surface roughness is achieved by changing the size of the
aluminum oxide particles applied to the surface. The application of
the aluminum oxide particles to roughen a surface substantially
minimizes the distortion to the surface, which occurs with
conventional blasting methods, and enables a user to control the
roughness of the surface. In addition, harder particles such as
boron nitride particles or other suitable particles can be applied
to the surface of the substrate to increase the penetration
resistance of the surface.
[0047] In a further alternative embodiment, the dry uniform
particles are pre-coated or encapsulated or micro-encapsulated or
micronized with a bonding enhancing material prior to applying the
dry particles to the wet bonding material layer on the surface of
the substrate. The pre-treated particles further enhance the
bonding strength of coated particles to the layers on the substrate
and to subsequent topcoat layers. The wet bonding material used to
pre-coat the dry particles may be the same or different than the
bonding material layer applied to the substrate.
[0048] In one embodiment, the present method described above is
used as a coating to attenuate or reduce magnetic, electromagnetic,
radio or similar waves generated by electric machines or other
devices. Electromagnetic absorbent particles such as metal
particles are used to coat a surface or surfaces. The particles
completely coat the surfaces and enhance the electromagnetic,
microwave or other wave absorbing capabilities of the surfaces.
[0049] In one embodiment, the present invention may be employed to
protect machine operators from potentially dangerous conditions.
Certain machines such as a Magnetic Resonance Imaging ("MRI")
machines produce potentially harmful conditions. Generally, a MRI
machine uses a nuclear magnetic resonance spectrometer to produce
electronic images of specific atoms and molecular structures in
solids, especially human cells, tissues, and organs. Exposure to
the magnetic frequencies and radiation generated by a MRI machine
over time may pose health risks to an operator. Similarly, it is
desirable to block exterior magnetic fields from such equipment.
Operators are protected and such equipment is usually protected
from exterior magnetic fields by RF enclosures or magnetically
shielded enclosures. Such enclosures include walls of layers of
magnetic shielding material such as copper. Such materials
including the fabrication and installation of such materials is
relatively expensive. In accordance with the present invention,
dense adsorptive coatings can be applied to the interior and/or
exterior surfaces of the walls of such enclosures and made of less
expensive materials. The dry particles can be round or flat flakes
or combinations of, for instance, dry copper round and flat
particles, assuring complete electrical conductivity. The dry
coating or wet coatings can incorporate substances such as metals,
which shield and absorb the magnetic frequencies and radiation. If
the coatings are applied in a high vibration area, elastomeric
urethanes and other suitable flexible bonding materials may be used
to prevent cracking or separations on the coated substrate.
[0050] In another embodiment, a liquid bonding material layer such
as an epoxy, which is thermally cured, is applied to the surface of
the substrate. Metal particles are then introduced or applied using
a dry powder spray mechanism. In one aspect of this embodiment, the
metal particles are passed through a heating chamber or flame
device, such as on a metal spray gun. The metal particles pass
through an oxyacetylene flame raising the temperature of the
particles as the particles are propelled towards the pre-applied
wet bonding layer. Introduction of heat into the particles allows
the wet bonding material layer to start curing or semi-curing. The
curing or semi-curing occurs because the heat introduced into the
coating starts to harden the bonding material layer after the
particles have been immersed in the material layer due to the
velocity and force of the particles propelled at the wet bonding
material layer. In a further embodiment, several different metals
are applied to the bonding material. In another embodiment, metals
and non-metals are combined and applied to the bonding material
layer to form the underlayment. Additionally, particles formed from
a material from the imide family and particles formed from another
family such as high-end imides can be used to form the reinforcing
underlayment.
[0051] In an alternative embodiment, a coating system includes a
plurality of coating applicators, at least one container having a
wet bonding material, at least one container having substantially
dry particles, wherein the containers are connected to the coating
applicators. The containers are connected to the coating
applicators with at least one coating line or tube, which
transports the materials from the containers to the coating
applicators. It should be appreciated that the coating applicators
may be spray guns, electrostatic spray guns, powder spray guns or
any other suitable applicators. The coating applicators are
positioned adjacent to the surface or surfaces being coated on the
substrate. Additionally, the coating applicators may apply the
coatings at the same rate or at different rates.
[0052] In one example, multiple coating applicators such as two
electrostatic spray guns or powder spray guns, apply an epoxy-based
material to a surface of a substrate. The epoxy is made up of
relatively dry particles which are applied using electrostatic
attraction to the surface. While the epoxy is in place, a thin
layer of a wet bonding material is fog-sprayed or applied to the
epoxy particles to slightly dampen the surface of the particles.
Then, a powder spray of aluminum oxide, bronze, ceramic, glass or
any other suitable material is applied to the bonding material on
the particles. The layers are then heated or cured at one time.
Subsequently, a final coating such as a wet or dry coating may be
applied to the cured layers as a final coating or topcoat.
[0053] In another embodiment, one or more additional bonding
material layers are applied to the first or primary bonding
material layer applied to the surface of the substrate to meet
specific design specifications or coating requirements of a
manufacturer. The bonding material layers may be the same or
different bonding materials and are applied to the first bonding
material layer until a predetermined thickness is achieved. The
uniform dry particles may be applied to any one of the reinforcing
material layers on the surface of the substrate. Additionally,
different materials may be added to the bonding material layer or
layers, based on specific design specifications.
[0054] In a further embodiment, the coated substrate is cured using
induction heating. In this embodiment, induction sensitive
particles such as metal particles are applied to the wet bonding
material on the surface of a substrate. The metal particles are
rearranged in the wet bonding material using a magnet and induction
waves, which are reverse magnetic fields, are then directed at the
coated substrate to induce heat in the wet bonding material. The
heat induced in the wet bonding material cures the wet bonding
material. In another embodiment, an induction heat device is used
to raise the temperature of the substrate and thereby cures the wet
bonding material layer.
[0055] It is therefore an advantage of the present invention to
provide a reinforcing underlayment and a method for manufacturing
the reinforcing underlayment that increases the desired final
system characteristics of a substrate.
[0056] Another advantage of the present invention to provide a
reinforcing underlayment and a method for manufacturing the
reinforcing underlayment that enhances, improves or changes the
inherent characteristics of a substrate or surface.
[0057] A further advantage of the present invention is to provide a
method for manufacturing for a coating underlayment which enables
the underlayment to be applied to a substrate as a single, even and
substantially uniform layer of particles.
[0058] Another advantage of the present invention is to provide a
method of manufacturing a coating underlayment that employs
substantially uniform particles to form the underlayment layer on a
substrate.
[0059] A further advantage of the present invention is to provide a
method of manufacturing a coating underlayment that employs
different sized particles and particles of different chemistries
and characteristics to form the underlayment layer on a
substrate.
[0060] Another advantage of the present invention is to provide a
coating underlayment and method of making the coating underlayment
that can be used on a wide variety of temperature sensitive
substrates and products.
[0061] A further advantage of the present invention is to provide a
coating underlayment apparatus and method which significantly
reduces capital equipment costs, operation costs and process
complications.
[0062] Additional features and advantages of the present invention
are described in and will be apparent from, the following Detailed
Description of the Invention and the Figures.
BRIEF DESCRIPTION OF THE FIGURES
[0063] FIG. 1A is an enlarged fragmentary side view of a coated
substrate of one embodiment of the present invention.
[0064] FIG. 1B is an enlarged fragmentary cross-sectional view of
the coated substrate of FIG. 1A taken substantially along the line
1B-1B.
[0065] FIG. 1C is an enlarged fragmentary side view of a coated
substrate of another embodiment of the present invention including
angular particles distributed on the surface of the substrate with
different densities.
[0066] FIG. 1D is a top view of the embodiment of FIG. 1C.
[0067] FIG. 1E is an enlarged fragmentary side view of a coated
substrate of another embodiment of the present invention including
spherical particles distributed on the surface of the substrate
with different densities.
[0068] FIG. 1F is an enlarged fragmentary side view of a coated
substrate of another embodiment of the present invention including
flake-shaped particles distributed on the surface of the substrate
with different densities.
[0069] FIG. 1G is an enlarged fragmentary side view of a coated
substrate of another embodiment of the present invention including
fiber particles distributed on the surface of the substrate with
different densities.
[0070] FIG. 1H is an enlarged fragmentary side view of a coated
substrate of another embodiment of the present invention including
spherical and flake-shaped particles distributed on the surface of
the substrate with different densities.
[0071] FIG. 1I is an enlarged fragmentary side view of a coated
substrate of another embodiment of the present invention including
spherical and fiber particles distributed on the surface of the
substrate with different densities.
[0072] FIG. 1J is an enlarged fragmentary side view of a coated
substrate of another embodiment of the present invention including
fiber and flake-shaped particles distributed on the surface of the
substrate with different densities.
[0073] FIG. 2A is an enlarged fragmentary side view of a coated
substrate of a another embodiment of the present invention
illustrating angular particles applied to the bonding material
layer on the surface of a substrate.
[0074] FIG. 2B is an enlarged fragmentary side view of the
embodiment of FIG. 2A where an abrasion resistant coating is
applied to the angular particle layer on the surface of the
substrate.
[0075] FIG. 3A is an enlarged fragmentary side view of a coated
substrate of a another embodiment of the present invention
illustrating different sized particles applied to the bonding
material layer on the surface of a substrate.
[0076] FIG. 3B is a top view of the embodiment of FIG. 3A.
[0077] FIG. 3C is an enlarged fragmentary side view of a coated
substrate of a further embodiment of the present invention
illustrating different sized particles applied to the bonding
material layer on the surface of a substrate.
[0078] FIG. 3D is a top view of the embodiment of FIG. 3C.
[0079] FIG. 4 is a flowchart illustrating one embodiment of the
coating method of the present invention.
[0080] FIG. 5A is an enlarged fragmentary side view of a coated
substrate of a further embodiment of the present invention
illustrating flake-shaped particles applied to the bonding material
layer on the surface of a substrate.
[0081] FIG. 5B is an enlarged fragmentary side view of a coated
substrate of another embodiment of the present invention
illustrating the wear pattern of ultra porous particles applied to
the bonding material layer on the surface of a substrate and the
attachment of the 80% worn particles due to the anchor pattern of
attachment or bonding sites within the porous particles.
[0082] FIG. 5C is an enlarged fragmentary side view of a coated
substrate of a further embodiment of the present invention
illustrating ultra porous metal particles infused with smaller
particles and a topcoat containing wear and friction reducing
agents.
[0083] FIG. 5D is an enlarged side view of one of the infused ultra
porous metal particles of the embodiment of FIG. 5C.
[0084] FIG. 6A is an enlarged fragmentary side view of a coated
substrate of another embodiment of the present invention
illustrating a coated substrate including a coating layer applied
to the bonding material layer.
[0085] FIG. 6B is an enlarged fragmentary cross-sectional view of
the coated substrate of FIG. 6A taken substantially along the line
6B-6B.
[0086] FIG. 6C is a top view of the embodiment of FIG. 6A.
[0087] FIG. 7A is an enlarged fragmentary side view of a coated
substrate of a further embodiment of the present invention
illustrating a coated substrate including multiple underlayment
layers and dry particles in each individual layer.
[0088] FIG. 7B is an enlarged fragmentary cross-sectional view of
the coated substrate of FIG. 7A taken substantially along the line
7B-7B.
[0089] FIG. 7C is an enlarged fragmentary side view of a coated
substrate of another embodiment of the present invention
illustrating a coated substrate including multiple underlayment
layers having spherical particles introduced into each individual
layer.
[0090] FIG. 7D is an enlarged fragmentary cross-sectional view of
the coated substrate of FIG. 7C taken substantially along the line
7D-7D.
[0091] FIG. 7E is an enlarged fragmentary side view of a coated
substrate of another embodiment of the present invention
illustrating a coated substrate including multiple underlayment
layers having angular particles.
[0092] FIG. 7F is an enlarged fragmentary cross-sectional view of
the coated substrate of FIG. 7E taken substantially along the line
7F-7F.
[0093] FIG. 8 is an enlarged fragmentary side view of a coated
substrate of a further embodiment of the present invention
illustrating the uniform particles as substantially uniform round
particles.
[0094] FIG. 9 is an enlarged fragmentary view of a coated substrate
of another embodiment of the present invention illustrating
multiple wet material bonding layers including hard and soft
particles applied to the surface of the substrate.
[0095] FIG. 10A is an enlarged fragmentary view of an example of
the coated substrate of FIG. 9 illustrating a stage of the process
for forming the coating on the substrate.
[0096] FIG. 10B is an enlarged fragmentary view of an example of
the coated substrate of FIG. 9 illustrating the final stage of the
process for forming the complete coated substrate.
DETAILED DESCRIPTION
Reinforcing Underlayment
[0097] Referring now to FIGS. 1A and 1B, one embodiment of a
product including the coating reinforcing underlayment of the
present invention is illustrated where a coating such as a topcoat
material is applied to an underlayment. In this embodiment, a
reinforcing underlayment 103a includes a wet bonding material layer
104a and a single layer of substantially uniform dry particles 106a
which are applied substantially evenly to the bonding material
layer on a surface of the substrate or product as shown in FIG. 1A.
The reinforcing underlayment of the present invention is employed
or used to facilitate the adherence of a coating to at least a
portion of the surface of the substrate. The substrate 102a
generally may be any suitable type of substrate such as a metal,
wood, plastic, glass or other suitable material.
[0098] A layer of wet bonding material 104a such as a separate
layer of an adhesion promoter or other suitable material or mixture
of materials, is applied to the surface of the substrate to be
coated to promote the adhesion of subsequent layers to the
substrate. In one embodiment, the wet bonding material is a
ultraviolet light cure resin. In another embodiment, the wet
bonding material includes an electron beam cure resin. It should be
appreciated that the bonding material layer 104a may be any
suitable wet bonding material with or without one or more additives
which change or enhance one or more characteristics of the wet
bonding material. In one embodiment, the wet bonding material layer
or film thickness ranges from five microns to one hundred fifty
microns or larger. The wet bonding material layer may therefore be
a thick layer where the uniform particles sink into and are
completely covered by the wet bonding material layer. In another
embodiment, the wet bonding material layer is a substantially thin
layer on the surface of the substrate and only a small portion of
the particles adhere to the thin, wet bonding material layer.
Furthermore, the reinforcing underlayment 103a includes a single
layer of substantially uniform dry particles 106a, which are evenly
distributed or applied to the wet bonding material layer 104a.
After the dry particles 106a are applied to the wet bonding
material layer and the wet bonding layer is cured, a reinforcing
material topcoat layer or reinforcing topcoat coating 108a is
applied to the reinforcing underlayment 103a. The reinforcing
topcoat coating 108a may be any suitable type of material or
coating applied to substrates such as a topcoat, paint, a corrosion
protective coating or other suitable materials or coatings that can
be mixtures of solid particles and liquid materials. It should also
be appreciated that the reinforcing topcoat coating may be any
suitable topcoat such as ultraviolet light cure resins or electron
beam cure resins. One or more reinforcing material layers or
reinforcing coatings may be applied to the layer of dry particles
based on the design specifications and the desires of the
manufacturer. The reinforcing material layers or coatings may be
the same materials or coatings, or different materials or coatings.
In one embodiment, the final topcoat reinforcing material layer(s)
is/are applied to the dry particle layer until a predetermined or
desired thickness is achieved. In another embodiment, the
reinforcing material layers and/or coatings are applied until the
layers and the substrate are a predetermined or desired total or
overall thickness.
[0099] After the coatings have been applied to the substrate, the
resultant structure of the underlayment 103a includes the dry
particles or granules introduced into the wet bonding material
layer where the wet bonding material layer adheres to various types
of surfaces of a substrate such as round or flat surfaces. In a
curing process, the dry particles 106a remain in place completely
covering the wet bonding layer 104a while the wet bonding material
layer 104a passes through phases until the dry particles and the
bonding material layer are fused together as the liquid layer is
cured. It should be appreciated that the bonding material layer
104a and uniform dry particles 106a may be partially cured or
completely cured depending on whether single or multiple bonding
material and dry particle layers are applied to the surface of the
substrate.
[0100] Referring to FIGS. 1C and 1D, another embodiment of the
present invention is illustrated where the coated substrate
includes uniform size angular particles distributed with varying
densities on the surface of the substrate. This type of
distribution may be employed on products such as cooking equipment
where greater abrasion resistance is desired in specific areas. For
example, the denser distribution of particles is applied to the
more abrasive areas to minimize the effects of the abrasion on the
surface. In FIG. 1C, a bonding material layer 104b is applied to
the surface of the substrate 102b. The angular particles 106b are
then applied with different distributions or varied densities on
the surface. The particles are applied to a suitable thickness such
as the thickness 103b. A topcoat or final coating 108b is applied
if desired, such as PTFE. In one embodiment, the topcoat is a
suitable solvent which is applied over the particles after the
particles are applied to the wet bonding material. The capillary
action of the solvents draws some of the wet bonding material up
over the particles as the solvent evaporates to strengthen the bond
of the particles to the wet material bonding layer. The final
coated substrate 100b therefore includes different densities of
uniform particles as shown in FIG. 1D.
[0101] Referring to FIGS. 1E to 1J, different types of particles
and different combinations of particles may be applied to the wet
bonding material layer on the surface of the substrate. In FIG. 1E,
different densities of spherical particles 106c are applied to the
wet bonding material layer. In FIG. 1F, different densities of
flake-shaped particles 106d are applied to the wet bonding material
layer. In FIG. 1G, different densities of fiber particles 106e are
applied to the wet bonding material layer. In FIG. 1H, different
densities of a combination of spherical particles 106c and
flake-shaped particles 106d are applied to the wet bonding material
layer. In FIG. 1I, different densities of a combination of
spherical particles 106c and fiber particles 106e are applied to
the wet bonding material layer. In FIG. 1J, different densities of
a combination of flake-shaped particles 106d and fiber particles
106e are applied to the wet bonding material layer. It should be
appreciated that any suitable combinations of the above particles
may be applied to the wet bonding material layer depending on the
end-use requirements and specifications.
[0102] The coating underlayment is primarily composed of
substantially uniform dry particles, which form a single
substantially uniform and substantially even layer on the surface
of the substrate or product. In one embodiment where abrasive
resistant surfaces are desired, the substantially uniform dry
particles may be any suitable size or shape as desired by the
manufacturer such as flat-shaped, flake-shaped, angular-shaped,
cylindrical-shaped, oblong-shaped and leaf-shaped particles.
Specifically, the substantially uniform dry particles are
substantially the same in size and shape for several reasons,
including so that the coating area or area of adhesion is maximized
on the surface of the substrate. In one embodiment shown in FIG.
2A, angular particles 206 such as triangular shaped particles are
used to create a rough surface on a substrate by applying the
angular particles to the bonding material layer 204 on the surface
of the substrate 202. In another embodiment, softer, less abrasive
surfaces are created by using shaped particles such as spherical
shaped particles. In a further example described in more detail
below, combinations of different shaped particles are used on a
surface of a substrate as shown in FIGS. 3A and 3B. Thus, uniformly
sized or shaped particles or different sized or shaped particles
may be applied to a surface of a substrate.
[0103] As indicated above, in one preferred embodiment, the wet
bonding material layer and the substantially uniform dry particle
layer are applied to the surface of the substrate until a desired
thickness is achieved. In one presently preferred embodiment, the
desired thickness is approximately 5 .mu.m to 100 .mu.m. Other
suitable thickness ranges may be used as desired by the
manufacturer. In FIG. 2B, an abrasion resistant topcoat or final
coating 208 is applied to the angular particles 206. The abrasion
resistant coating further enhances the abrasion resistant
characteristics of the surface of the substrate.
[0104] In another embodiment, the substantially uniform dry
particle layer is composed of substantially spherical particles,
which creates a softer, less abrasive surface on the substrate. It
should be appreciated that the particles may be spherical
particles, substantially flat flakes, fibers or any suitable shape
or combination of shapes as described above, which maximizes the
surface area of the uniform particle layer. Additionally, the size
of the dry particles may be changed as desired to accommodate
different technical and coating requirements or specifications. In
one embodiment, the dry particles include at least one relatively
large particle and at least one relatively small particle. In
another embodiment, the dry particles range in size such as from a
sub-micron to approximately 125-150 microns.
[0105] The density of the uniform particles on the wet bonding
material layer on the surface of a substrate may be changed or
enhanced to strengthen the bond of the particles in the layer. In
one embodiment, the particles are applied to the wet bonding
material layer and then the part is vibrated to settle the
particles into the wet bonding material layer. In another
embodiment, a wet bonding material layer and a layer of
substantially uniform particles are applied to a surface of a
substrate such as a round part having an internal bore. The part is
rotated, which causes the particles to densify or pack together in
the wet bonding material due to the centrifugal force of the
spinning part.
[0106] Referring to FIGS. 3A and 3B, the uniform particle layer
includes different sized spherical particles 306a and 306b applied
to the bonding material layer 304 on the surface of the substrate
302. In one example, the smaller sized particles 306b are softer
particles and the larger sized particles 306a are harder particles
such that the soft particles provide lower friction and the hard
particles enhance the abrasion resistance of the surface as
described in more detail below. Another example, hard abrasion
resistant larger size particles and smaller electrically conductive
particles are applied to create an abrasion resistant and
electrically conductive reinforcement underlayer. A topcoat or
final coating 308 of a suitable material is applied to the uniform
particle layer. In FIGS. 3C and 3D, another aspect of this
embodiment is illustrated where different sized angular particles
306c and 306d are applied to the wet bonding material layer 304 on
the surface of the substrate 302. It should be appreciated that any
sizes and shaped particles may be applied to the surface of the
substrate.
Coating Underlayment Method
[0107] Referring to FIG. 4, one embodiment of the method of
applying the coating underlayment to form a coated substrate is
illustrated in the flow diagram. In the method illustrated in FIG.
4, one or more surfaces to be coated on a substrate are cleaned
using a suitable cleaner as indicated in block 400. The cleaner
removes a substantial portion of or all of the impurities that may
be on the surface of the substrate which may inhibit the adhesion
of one or more of the layers to the substrate. The surfaces to be
coated may be cleaned manually or mechanically in an automated
process. The substrate may be cleaned using any suitable cleaning
process such as grit blasting or sandblasting, which slightly
roughens and cleans the surface or surfaces of a substrate.
Additionally, the substrate may be pre-cleaned in a clean room or
similar manufacturing area where the step described in block 400 is
not necessary.
[0108] After the substrate is cleaned or is clean, a layer of a
substantially wet bonding material is applied to the substrate as
indicated by block 402. The bonding material provides a wet or
moist surface for the subsequent substantially uniform dry particle
layer to adhere to. The wet bonding material may be any suitable
bonding material, which meets the specific design specifications of
the particular product or substrate. In this embodiment, it is
important that the bonding material remain wet prior to the
application of the uniform dry particle layer so that the dry
particles stick to or adhere to the wet bonding material. As
described in block 404, in this embodiment, a single layer of
substantially uniform dry particles are applied or sprayed onto the
wet bonding material layer until the wet bonding material layer is
completely coated with the dry uniform particles and a desired
thickness is achieved. The thickness of the coatings or coating
layers is dependent on the specifications for the particular
product, the amount of bonding material applied and the size and
shape of the dry particles.
[0109] In one embodiment, the substantially uniform dry particles
are sprayed or applied onto the wet bonding material as a single
substantially uniform and substantially even layer which adheres to
the sticky or wet surface of the bonding material. In another
embodiment, the substrate is electrically grounded using a suitable
grounding method. Grounding the substrate thereby grounds the wet
bonding material layer, which is formulated to include solvents
and/or liquids that conduct electrical energy. The substantially
uniform dry particle layer has or will have an opposite electrical
charge to that of the bonding material layer and therefore is
electrically or electrostatically attracted to the wet bonding
material layer as the dry particles are applied to that layer. In a
further embodiment, an applicator such as a sifter is used to
uniformly apply the uniform particles to the wet bonding material
layer. The sifter is similar to a conventional flour sifter or a
drum sifter and is used in certain applications depending on the
required application of the uniform particles.
[0110] In another embodiment illustrated in FIG. 5A, an
electrically conductive liquid bonding material layer is applied to
the surface of the substrate to enhance the attraction of the dry
particles, which may be material flakes (as shown in FIG. 5),
ceramic or plastic particles and also specially treated or
untreated particles, such as bronze, brass, zinc, copper, steel,
stainless steel, aluminum, graphite, titanium, molybdenum
disulfide, molybdenum, talc, lead, antimony, tin, silver, titanium
and nickel or any other suitable metals, alloys, ceramics or
plastics. The oppositely charged or tribo-charged (i.e., friction
charged) electrical attraction of the dry particles or flakes 506
to the wet bonding material layer 504 promotes the adhesion and
uniformity of coverage of the dry particles to the bonding material
layer. The metal particles can be propelled toward the wet surface
with air or gasses that have been ionized or treated to momentarily
electrically charge the metal conductive particles with the
opposite charge of the wet surface of the substrate. The result is
a dense, substantially uniform and evenly distributed particle
layer or underlayment layer on the surface of the substrate
502.
[0111] In another embodiment, a liquid bonding material layer such
as an epoxy, which is thermally cured, is applied to the surface of
the substrate. The metal particles are then introduced using a dry
powder spray mechanism. In one aspect of this embodiment, the metal
particles are passed through a heating chamber or flame device,
such as on a metal spray gun. The metal particles pass through an
oxyacetylene flame raising the temperature of the particles as the
particles are propelled towards the pre-applied wet bonding layer.
Introduction of heat into the particles allows the wet bonding
material layer to start curing or semi-curing. The curing or
semi-curing occurs because the heat introduced into the coating
starts to harden the bonding material layer after the particles
have been immersed in the material layer due to the velocity and
force of the particles propelled at the wet bonding material
layer.
[0112] In a further embodiment, several different metals are
applied to a bonding material layer on a surface of a substrate. In
one example, bronze particles having a size of 35-microns and lead
particles having a size of 5-microns are sequentially applied to a
bonding material layer on a surface of a substrate. In another
example, metals and non-metals are combined to form the
underlayment. For instance, bronze particles and pre-cured
imide-amide particles can be applied to the bonding material layer.
Additionally, particles formed from a material from the imide
family and particles formed from another family such as high-end
imides can be applied to the bonding material layer. This
combination allows the bronze to dissipate or absorb surface heat
and conduct heat away from the surface of the substrate. The
engineering plastic materials described above can be used instead
of the bronze particles if much lower friction is desired.
[0113] Referring now again to FIG. 4, after the substantially
uniform particle layer is applied to the bonding material layer,
the layers are cured to strengthen the bond between the uniform dry
particle layer and the wet primer layer on the surface of substrate
as indicated by block 406. The curing process may be performed by
heating the layers at a predetermined temperature or temperatures,
air-drying the layers or by utilizing any suitable internal or
external curing or cross linking process. In addition, the curing
process may use a single or plural package heat cure or air-dry
materials, such as polyimide for heat cure applications and
acrylics for air-dry applications and two part epoxies for room
temperature or U.V. rapid curing. When the substantially uniform
dry particle layer has completed adhered or bonded to the bonding
material layer, a suitable coating layer is applied to the uniform
dry particle layer as indicated in block 408. The coating may be
any suitable coating such as a topcoat or final coat material.
Examples include corrosive or abrasive resistant coatings,
non-stick coatings or low friction coatings and electrically
insulative or conductive coatings or combinations thereof.
[0114] The substantially uniform dry particle layer maximizes the
surface area exposed to the coating applied to that surface of the
particles. Increasing the surface area for the application of a
coating to that area, enables the coating to develop a very strong
mechanical bond to the underlayment layer and ultimately to the
substrate. The strong bond between the coating and the underlayment
layer promotes the durability and strength of the coating on a
product or substrate. Furthermore, the coating underlayment layer
also promotes a substantially even and uniform distribution of the
coating to the substrate. Optimum adhesion is provided by the first
wet bonding layer on the surface to the subsequently applied
particles. The second wet coating is formulated to provide optimum
adhesion to the particles and provide specific characteristic to
the final surface as determined by the use of the final surface.
This minimizes the defects or uneven distribution of the coating on
the surface of the substrate and promotes the maximum functional
values of the coated part. Thus, less parts or products are
discarded due to uneven coating or defective coating layers on a
substrate or product and the coating provides the maximum
functional characteristics with minimal compromises of the
functional characteristics of the finished or complete coating.
Uniform Particle Embodiments
[0115] The types of particles applied to the surface of a substrate
vary based on the specific requirements of a substrate or based on
the environment in which the substrate is being used. In one
embodiment, dry or powdered carbon particles or whiskers such as
carbon fiber particles or whiskers are applied to a substrate to
prevent wear of a surface on the substrate and to provide a
non-metallic conductive surface. The dry or powdered carbon fibers
are substantially uniform fibers applied to a wet bonding material
layer such as a primer on a surface of a substrate. In one example,
a substrate including carbon fiber particles is used for high
temperature commercial knives and cutting blades where static
electricity must be dissipated. In another example, a substrate
including carbon fiber particles is used for conveyors to transport
paper and other static electricity producing materials, such as
plastic. In this embodiment, the wear reduction capabilities of a
substrate are vastly improved with the carbon fibers, which can be
as small as approximately three microns in diameter and
approximately 20-30 microns long. When the carbon fibers are dry
sprayed onto the bonding material layer, the shorter fibers orient
themselves in multiple directions thereby enhancing the wear
resistance of the carbon fiber layer (the end of the carbon fiber
particles do protrude through the final coating surface). The
bonding matrix is designed according to end use or design
specifications. The carbon fibers may include a high or low
temperature material.
[0116] In another embodiment, aramid fibers or engineered plastic
particles or fibers are applied to a substrate to strengthen the
surface of the substrate. The aramid fibers may any suitable aramid
material such as Kevlar.RTM., which is manufactured and sold by the
E.I. du Pont de Nemours Company. The aramid or Kevlar.RTM. fibers
are applied to the bonding material layer in very much the same
manner as the carbon fibers or whiskers. The Kevlar.RTM. fibers or
materials can be either a pulp, which includes loose, fluffy fibers
which is further ground into a fine powder, or can be other
suitable forms such as round particles or semi-round particles. The
aramid particles provide non-metallic wear resistance and have good
bonding ability with both the basecoat and subsequent topcoats.
Thus, the applied aramid fibers or materials create a dense layer
of aramid or Kevlar.RTM. particles on the surface of the substrate,
which is then coated with a topcoat or other suitable final
coating. However, if a very high temperature non-metallic or
non-ceramic, moderate friction (i.e., low abrasion) surface is
desired, a topcoat or final coating is not applied to the layer of
aramid fibers as in a brake surface or clutch facing, or a specific
high temperature topcoat formulation may be applied as an
option.
[0117] In another embodiment, individual and/or combinations of
aramid fibers or particles, which may be any random shape and size,
are applied to the surface of the substrate. In this embodiment,
the dry aramid particles or fibers are applied to the wet bonding
layer, which has been previously applied to the surface of the
substrate. Because the aramid fibers have extreme temperature
resistance compared to most polymers and organics, the aramid
fibers or particles can be topcoated with a very high temperature
PTFE or silicone type resin. Therefore, the temperature resistance,
non-stick capability and wear resistance of the final coated
surface is equivalent to and sometimes greater than the same
properties for metal fibers or particles.
[0118] In one example, the aramid fibers are used as a clutch
facing or in a braking mechanism in a tightly contained space. In
this example, an aluminum brake shoe is pre-coated with a wet
silicone or high temperature imide-amide material layer, then a
layer of aramid fibers or particles, followed by another wet
silicone or imide-amide layer, and then a imide-amide particle
material layer. In one example application of the present
invention, a motorcycle clutch disc is manufactured of aluminum and
then, using this method to provide wear resistance, eliminates the
steel clutch disc construction and reduce the weight of the clutch
assembly by more than fifty percent. The aramid fibers reduce and
prevent galling and seizure of counter surfaces because of the
aramid fibers extremely high temperature capability and ability to
char and ablate at the outer surfaces in the presence of oxygen and
high scuffing at relative speeds. Additionally, a thin topcoat of
PTFE, graphite or another suitable lubricant film can be applied to
the aramid particle layer to assist the break in of the counter
surface or surfaces.
[0119] In a further embodiment, specially treated, uniform plastic
particles are applied to a wet bonding layer as applied to a
substrate. The plastic particles are pre-treated PTFE, UHMW and/or
polyethylene (PE) or another suitable material and applied to the
wet bonding material on the surface of the substrate. The particles
are pre-irradiated or processed with an electron beam or other
suitable method which causes the particles to be able to sink into
the wet bonding material layer, instead of remaining on the top of
the wet material bonding layer. Therefore, the plastic particles
are strongly bonded to the layer and not easily dislodged from the
surface. This process thereby enables the plastic particle layer to
last longer.
[0120] In another embodiment, dry or powdered anti-microbial
particles which reduce and kill bacteria and other microbials are
applied to the wet bonding material layer on the surface of a
substrate. In one aspect of this embodiment, a final coating or
topcoat is not applied to the dry anti-microbial particles or
powder layer, which enables the anti-microbial particles to remain
at the surface. In another aspect of this embodiment, a thin
topcoat or final coating such as polytetrafluorethylene (PTFE) is
applied to the anti-microbial particulate layer to perform a
release function such as a non-stick coating on the surfaces of
cooking equipment. In one example, a counter top such as a kitchen
counter, is coated with a two part epoxy followed by a powder
coating of anti-microbial material. Then, a thin coating of the
epoxy is applied to the anti-microbial particulate layer as a final
coating or topcoat. Such a counter may be used in a meat packing
plant to kill harmful bacteria on counters where the meat is cut
and packaged or the anti-microbial coating may be used on hooks or
similar conveying equipment in a meat packing house. The
anti-microbial effect of the coatings on the counters can be
maintained by repeating the coating process on the counter surfaces
periodically as needed. It should be appreciated that any suitable
anti-microbial particles or material such as silver, silver-ceramic
or silver compounds may be used in the above embodiment.
[0121] In a further embodiment, dry or powdered, ultra porous
bronze or other porous particles are applied to the wet bonding
material layer on the surface of a substrate. The ultra porous
bronze particles are "sponge-like" particles that include many
openings and voids such that the particles are approximately
seventy percent solid compared to over ninety percent solid for
other porous bronze materials. The ultra porous bronze particles
are infused with the wet bonding material after the bronze
particles are deposited on the wet bonding material on a surface of
a substrate. The infused or vacuum infused material layer permeates
the pores of the bronze particles and bonds to the "mini-tunnels"
in the particles. The infused layer adds lubrication and increases
the bonding strength of the layers to hold the bronze particles to
both the upper and lower coating layers and to the surface of the
substrate. Thus, this process "locks" the ultra porous particles
into the wet bonding material layer, which prevents the particles
from dislodging easily from the wet bonding material layer as they
wear.
[0122] FIG. 5B illustrates the secure bond of the ultra porous
particles in the bonding material layer. The ultra porous particles
are applied to a wet bonding material layer 510 on the surface of a
substrate 508 as described above. In addition, a topcoat or final
coating 513 of a suitable material such as PTFE is applied to
provide further wear resistance. In FIG. 5B, Section I shows that
initially one hundred percent of the ultra porous particles are
applied to the wet bonding material where there is zero percent
wear of the particles. After the topcoat 513 is completely worn
away and after the ultra porous particles are worn down to
approximately fifty percent of the particles original size as shown
in Section II of FIG. 5B, the particles still strongly adhere to
wet bonding material 510. As shown in Section III, after some
additional time, almost all of the particles remain adhered to the
bonding material layer even after approximately eighty percent of
the particles has been worn away. In one embodiment, a special
topcoat layer including a high solid material which migrates into
the pores of the attached bronze particles is applied to the
particles, either after the first curing process or as part of the
first bonding material layer applied to the surface of the
substrate.
[0123] In another embodiment, porous metal particles such as the
bronze particles described above are impregnated or infused with a
material such as PTFE, which lowers the friction of the particles.
In one aspect of this embodiment, bronze particles defining or
including seventy percent voids (i.e., air) is vacuum impregnated
with a suitable material such as PTFE. In another aspect of this
embodiment, the bronze particles are soaked with the PTFE and the
dried. The latter process leaves partial voids in the particles
where the particles are approximately forty percent solids. It
should be appreciated that any suitable metal or metal alloy or
ceramic particle or particles may be used as the base particles. It
should also be appreciated that any suitable low friction material
such as PTFE, anerobic polyester and UHMW may be used to fill or
partially fill the voids.
[0124] Referring to FIGS. 5C and 5D, in another embodiment, a
topcoat material 526 including lubricative particles 527 is applied
to the ultra porous bronze particles 524 in the bonding material
layer 522 on the surface of a substrate 520. The applied
lubricative particles 527 infuse the voided centers 525 of the
ultra porous bronze particles to enhance the lubrication associated
with the particles and reduce the friction on the particles. The
lubricative particles 527 may contain PTFE, graphite or any
suitable non-abrasive and/or non-stick material. It should be
appreciated that the porous particles may be any suitable porous
metal particles such as stainless steel particles, nickel
particles, bronze particles, iron particles, titanium particles and
suitable particles including a metal and/or metal alloys and also
porous ceramic particles which can be infused with conductive
particles such as carbon.
Additional Material Layers
[0125] In a further embodiment, catalyzed bonding materials such as
epoxies and urethanes are used in the present method to enhance the
bond strength and lower the curing temperature of the coatings.
These bonding agents will be tailored to the desired end use
characteristics and also to the temperature capabilities of the
substrate. In one example, the flexibility of cure temperature and
bond strengths is demonstrated by the bonding of pure bronze
particles to a commercial glass-filled plastic engineering
component, such as a sliding block contact in an electrical switch
gear. The lightweight, rigid engineering glass reinforced plastic
conducts no electricity. By adding a layer of bronze, copper, and
silver in successive layers, an impact-resistant material is
created which contacts a switch gear and makes electrical contact.
This may be used, for example, for a safety switch, where the
safety switch must be very light weight to respond mechanically
quickly in a safety situation. This embodiment may also be employed
in a radio wave and electromagnetic environment to absorb radio
frequencies (RF) and electromagnetic waves.
[0126] In another embodiment, acid or chemical resistance is
increased by applying a protective, non-metallic, non-plastic
material such as dry ceramic, glass, mica flakes and/or mica
particles to the wet bonding material layer. The dry ceramic or
mica flakes and/or particles create a barrier or a substantial
barrier to an acid or other chemical. The non-metallic, non-plastic
material may be any suitable materials such as ceramics, glass,
modified mica, mica, boron nitride, silica nitride and aluminum
oxide. The barrier diverts the acid or chemical by creating a
torturous path or a maze-like path which the acid or chemical
cannot avoid as it attempts to penetrate the protective coating.
Therefore, the acid or chemical is prevented from directly
attacking a base material such as a metal, by decreasing the
inherent permeability and porosity of a base coating or coatings
such as a fluoropolymer based acid resistant coating.
[0127] Referring to FIGS. 6A, 6B and 6C a further embodiment of the
present invention is illustrated where a coated substrate 600
includes one or more additional wet bonding material layers applied
to the primary or first wet bonding material layer based on
specific design specification or manufacturer requirements. The
bonding material layers are applied to the first bonding material
layer prior to applying the layer of substantially uniform dry
particles. In one embodiment, the additional or subsequent bonding
material layers include different bonding materials. In another
embodiment, the layers include the same bonding material, which is
applied to the first bonding material layer to a desired thickness,
such as a thickness, t. First, a desired substrate 602 such as a
metal substrate is first determined by the manufacturer. Then, the
first bonding material layer 604 is applied to the surface of the
substrate 602. A second or additional bonding material layer 605 is
applied to the first bonding material layer 604. The layer of
substantially uniform dry particles 606, which are substantially
uniform in shape and size, is applied onto the second bonding
material layer or top bonding material layer. The thickness of the
subsequent bonding material layers applied to the substrate are
generally predetermined according to a design specification or
manufacturer requirements. A suitable topcoat or final coating
layer 608 is applied to the uniform particles to achieve the final
coated substrate. It should be appreciated that the thickness of
the bonding material layers or coatings on the substrate or the
thickness of the overall substrate may vary according to the design
specifications. Thus, the final coated product or substrate 600 may
be any suitable thickness or composition. Additionally, it should
be appreciated that other suitable material layers may be applied
to the wet bonding material layer based on specific design
specifications or requirements. The material layers may include the
same or different materials.
[0128] In FIGS. 6B and 6C, the dry particles 606 are uniformly
distributed on the material bonding layer or primer layer 604 so
that the dry particles 606 are dense and cover every facet of the
surface on the primer layer. By using a single layer of
substantially uniform dry particles, the topcoat adheres to the
maximum surface area of the particles and thereby develops an
extremely strong bond between the coating layer and the particles
606 of the underlayment 603a. In one embodiment, a single,
substantially uniform dry particle layer 606 is applied to a
substrate to promote the adhesion of a coating to the substrate or
product. In another embodiment, the method of coating a substrate
using the underlayment as described above, may be repeated to apply
multiple reinforcing coatings or reinforcing material layers such
as multiple topcoatings to the substrate. In this embodiment, the
reinforcing material layers are applied until a desired thickness
is achieved. The desired thickness may be any desired thickness or
suitable thickness predetermined by the manufacturer. Thus, the
present embodiment of the underlayment may be used to apply
multiple reinforcing coatings or reinforcing material layers to a
single substrate and to multiple surfaces on a substrate.
[0129] Referring to FIG. 9, in another embodiment, a wet bonding
material layer 904a including relatively small particles 906b of a
suitable low friction or soft material such as PTFE or UHMW is
first applied to the surface of a substrate 902 as shown in the
left section. Next, a layer of uniform hard dry particles 906a such
as bronze particles or other suitable hard particles is applied to
the wet bonding material layer. Then another layer of the initial
wet bonding material mixture 904b including the relatively smaller
particles is applied to the dry particle layer as shown in the
middle section. The layers are dried and dissolved using a suitable
curing process or other suitable drying process. This causes the
top layer or second wet bonding material layer including the small
soft particles to shrink and distribute the small soft particles
amongst the hard bronze particles as shown in the right section.
This creates an abrasion resistant and low friction surface.
[0130] Referring to FIGS. 10A and 10B, in another embodiment, an
initial wet bonding material layer 1003 including relatively small
silver plated copper flakes 1007 and spherical copper particles
1004 are applied to a surface of a substrate 1002. Then, a second
wet bonding material layer 1006 including the same mixture of
smaller silver-plated copper particles is applied to the surface. A
solvent layer 1008 is then applied as a topcoat or final coating on
the two wet layers. The layers are then dried using a suitable
drying or curing process. This dissolves the solvent layer as shown
in FIG. 10B, and partially dissolves the second or top wet material
bonding layer to smoothen and sink the silver plated copper flakes
and copper particles in the initial wet bonding material layer. The
resultant surface includes hard metal particles which resist
abrasion while the softer small particles reduce friction on the
surface.
Multiple Underlayments
[0131] Referring now to FIGS. 7A and 7B, multiple underlayments,
such as underlayments 703a, 703b and 703c, are applied to a surface
of a substrate. The underlayments are applied to create a thicker
film on the substrate based on desired design specifications or
other suitable design requirements of a manufacturer. Two or more
underlayments 703 may be applied to the surface of the substrate.
In FIGS. 7A and 7B, in one example, a substrate 702 is first coated
with a first layer of a wet bonding material 704a. A first
substantially uniform layer of dry particles 706a is applied to the
first bonding material layer 704a. A second bonding material layer
704b is then applied to the first layer of dry particles 706a.
Then, a second substantially uniform layer of dry particles is
applied to the second bonding layer 704b. A third bonding material
layer 704c is applied to the second uniform layer of dry particles
706b. A third layer of substantially uniform dry particles 706c is
applied to the third bonding material layer 704c. The combination
and thickness of the layers or film is determined by the desired
design specifications for the layers on the surface of the
substrate. A suitable topcoat or final coating material 708 is then
applied to the final uniform particle layer 706c. It should be
appreciated that any suitable thicknesses or coating layer or layer
combinations may be applied to the surface of a substrate.
[0132] Referring to FIGS. 7C and 7D, another example of the
embodiment illustrated in FIGS. 7A and 7B are illustrated where the
multiple underlayments include substantially spherical particles
706a, 706b and 706c. In FIGS. 7E and 7F, the particles 706a, 706b
and 706c are angular particles which are applied in the
underlayment layers. It should be appreciated that any suitably
shaped uniform particles may be applied to the wet bonding material
layers based on the design specifications and end-use criteria.
[0133] In the alternative embodiments of the present invention, if
wear resistance is required, then the second layer or layer of
substantially uniform dry particles is generally the final layer
applied to the surface of a substrate. If non-stick or high
corrosion resistance is required, then a third and/or fourth wet
coating layer or topcoat including a suitable non-stick material or
similar material is added to the above layers to increase the
non-stick characteristic of the surface of the finished, coated
substrate.
[0134] Several different types of additives may be added to the
topcoat or final coating to improve the performance characteristics
of the coated substrate. In one embodiment, a counterface or
opposing surface smoothening additive including relatively hard,
relatively smaller particles, is added to a topcoat or final coat,
to enable the coated substrate to smoothen or polish a rough
surface or surfaces, which contact the surface of the coated
substrate. In one example, when rough metal surfaces rub against
PTFE coated substrates, the PTFE wears away. Quickly, this
diminishes the quality and performance of the PTFE on the coated
substrate. To remedy this problem, a smoothening additive is added
into the wet topcoat of PTFE so that the topcoat or outer layer on
the surface of the substrate contains harder particles than the
counter surface such as a metal surface. The relative motion
between the surface of the coated substrate and the rough metal
surface (i.e., the interface), causes the additive particles to
disperse as the particles wear away, and also polishes or smoothens
the opposing surface of relatively rough metal so that the PTFE
topcoat is not worn away prematurely. This also enables the layer
below the topcoat to have a smooth counter surface to work against.
It should be appreciated that any suitable additive may be added to
the topcoat or final coating to improve the performance or desired
characteristics of the coated substrate.
EXAMPLES
[0135] The above embodiments may be employed in several types of
coating processes. In one example, a soft coating, which is
commonly used to coat surfaces of cooking equipment, is applied to
one or more surfaces of a substrate.
[0136] The surface is prepared with cleaning and/or grit blasting
to uniformly roughen and clean the oxide layer off the surface,
whether it be aluminum, aluminum oxide, steel, glass, ceramic,
plastic or any suitable material. A primer bonding mixture or
solution including a wet layer of a polyamide-imide (PAI) material
is solvated in or dissolved in a solvent comprising a resin such as
N-methylpryrrolidine (NMP) is sprayed onto the surface of the
substrate so that the thickness of the wet mixture or solution is
approximately between 30-50 microns thick. Alternatively, other
suitable application methods such as dipping the substrate into the
solution or flowing the mixture or solution onto the surface of the
substrate may be used to apply the solution to the surface of the
substrate. The solids in the PAI is approximately fifteen percent
and solids in the NMP vehicle is approximately eighty-five percent.
Dry particles or granules of aluminum oxide are then applied to the
bonding layer. Preferably, the aluminum oxide particles protrude
through and are held by the bonding layer. The particles in this
example are approximately 50-60 microns in size which, when the
bonding layer shrinks because it is comprised of eighty-five
percent solvent and fifteen percent PAI resin, leaves a rough
surface not unlike commercial sandpaper. The exception is that each
particle has been completely coated with the diluted primer bonding
mixture.
[0137] In this example, the dry particles are completely coated
with the primer bonding mixture because the dry particles are one
hundred percent solids, where the primer bonding mixture is
primarily a liquid including approximately twelve to twenty-five
percent solids. As the liquid bonding material shrinks, it adheres
the particles to the substrate through adhesive bonding of the
amide-imide to the substrate to itself and to the introduced
particles. The resultant underlayment is cured at approximately
300-600 degrees Fahrenheit, depending on the subsequent coating or
coatings, if any, which may be applied to the underlayment.
[0138] In another example, an amide-imide (AI)/PTFE primer or
intermediate compatible material layer, which is compatible with
and bonds to the amide-imide layer is applied to the substrate. In
this example, the material layers are not cured. However, in one
embodiment, a semi-cure of 400 degrees Fahrenheit is used after
this phase to cure the layers on the substrate. A relatively pure
PTFE coating dispersed in water and some added component of NMP is
applied on top of the intermediate PTFE-AI layer. This last coat is
flash dried at approximately 200 degrees Fahrenheit until all the
water is removed. What remains is the aluminum oxide material held
to the surface by, at the bottom of the particles near the
substrate, a pure layer of PAI. The next layer still covering the
dry aluminum oxide particles includes the intermediate or primer
layer of the PTFE topcoat. In one embodiment, the PTFE topcoat has
a thickness of approximately 10-15 microns. The intermediate
PTFE-PAI coating is in a dry state and has a thickness of
approximately 10-20 microns. The purpose of this method is to cover
the largest particles of aluminum oxide to approximately 10-15
microns with a PTFE-rich topcoat. The resulting system is passed
through an oven with temperature zones of approximately 400 degrees
in a first phase to approximately 600 degrees to approximately 800
degrees in a third phase. At approximately 400 degrees, the
remaining NMP in the basecoat comes through the liquid layers and
helps to unify the bond of all three original liquid layers all of
which contain amide-imide (AI). At approximately 600 degrees
Fahrenheit, all of the volatiles and solvents are removed by heat
evaporation, along with any wetting agents. At approximately 800
degrees Fahrenheit, the PTFE sinters to itself, the amide-imide
bonds to the substrate and to the PTFE with a very high bond
strength, and the dry aluminum oxide particles are held together by
both the lower layer and the intermediate layer of AI coating.
[0139] In the above example, wear of the PTFE, which is soft and
has non-stick properties, is substantially minimized on the surface
of the substrate. Over time, the PTFE layer is worn away until the
wear-producing object or objects contact the aluminum oxide layer,
which has a substantial hardness of nine on a Mohs' scale. This
near-diamond hard material includes jagged peaks as its particulate
shape is very angular and multi-faceted. As the entire system is
worn, only the peaks of the dry aluminum oxide layer stick through
and support each other during the bonding of the lower and
intermediate layers. The strength and hardness of the aluminum
oxide layer prevents the PTFE from being worn away easily as the
rough "mountains" or peaks of aluminum oxide have surrounding
"valleys" filled with PTFE, which is protected by the aluminum
oxide "mountains." In fact, the aluminum oxide layer must be worn
away before the PTFE is able to be worn away. The chemical and
mechanical bonds of the PTFE layer to the intermediate and lower
layers are so strong that the layers are not dislodged even from
substantial cavitation pressures or hydraulic pressures.
Essentially, the entire underlayment is locked or secured together.
In one embodiment, the quantity of PTFE at the surface is reduced
as wear takes place. However, even the partially worn underlayment
remains effective as a non-stick layer such as a food contact
release when the underlayment still includes approximately 50%
PTFE. The PTFE remains effective because the low surface energy of
the remaining PTFE layer repels any sticky or substantially sticky
products. It should be appreciated that other suitable ceramic or
metallic materials including non-stick or lower surface energy
characteristics may be employed in the above embodiment instead of
aluminum oxide.
[0140] In another embodiment, the shape of the dry particles or
granules is changed such as to a rounder or spherical particle in a
wear resistant application so as to minimize wear or "scratching"
of an opposing surface. Additionally, using softer or harder
ceramic materials or particles reduces the wear or scratching of
the opposing surface or surfaces. As a result, the underlayment can
be used in several different applications or products such as on
the bottom of a frying pan, which has little or no PTFE.
[0141] In a further embodiment, higher temperature, rigid imide
resins of particle sizes similar to those of aluminum oxide,
approximately 40-60 microns, are used to make an even tougher
system including no ceramic material and with a more cushioning or
softer effect on the opposing counterface or surface. In one
example, a conveyor for transporting glass could be processed using
the non-ceramic underlayment particles and provide extraordinary
wear yet very slippery surfaces that will not scratch the glass
surfaces transported on the conveyor.
[0142] In a further example, the amide-imide is used as a bonding
material or primer in the underlayment. Also, round bronze dry
particles that can be solid or porous, are used in the underlayment
instead of abrasive, angular particles. As a result, the
underlayment provides wear resistance and reduction in an
oil-wetted or oil-containing environment, such as in an automobile
shock absorber. Additionally, other automobile parts including wear
surfaces such as the rod guide and the wear band on a piston, can
be manufactured using the underlayment of this embodiment.
Furthermore, graphite, molybdenum disulfide or other additives can
be added to the intermediate layer and/or upper coating or topcoat
layer to improve the lubrication characteristics of the automobile
or appliance parts or other similar parts or products. In the above
embodiments, the dry bronze particles are covered by a PTFE or
PTFE/resin material including wear-reducing agents such as
molybdenum disulfide, graphite, talc, or particles of lead, zinc,
antimony, tin, titanium or any other suitable material. Thus, the
above embodiments may be used for commercial sliding tables,
machine tools, automobile parts and other similar applications to
enhance the wear resistance and load carrying capacity and still
minimize the friction on the PTFE or PTFE containing intermediate
and topcoat layers.
Different Sized Particles
[0143] Referring back to FIG. 3 in another embodiment, two
different sized particles are applied to a substrate 302 to further
enhance the wear-reducing capabilities of a surface of the
substrate. The bonding material layer or primer layer 304 is
applied first to the surface of the substrate 302, and then several
large, dry metal particles 306a such as 125-micron bronze particles
are applied to the bonding material layer. Then smaller metal
particles 306b such as 25-30 micron lead particles are applied to
the initial metal particle layer as an intermediate coating layer
or as a topcoat layer. The underlayment of this embodiment
therefore provides different wear characteristics based on the
different counter surfaces and surfaces of a substrate or
substrates.
[0144] Referring now to FIG. 8, another embodiment of the present
invention is illustrated where the underlayment includes a single
uniform layer of substantially spherical or round, dry particles
806. The spherical particles are substantially uniform in size and
shape and are applied to a bonding material layer 804 on a surface.
A suitable topcoat or final coating 808 is then applied to the
uniform particles. The uniform size and shape of the spherical
particles promotes the increase of the surface area for a coating
to bond to the particles and also reduces the relatively soft
particle coating wear rates. It should be appreciated that any
substantially uniform size or shaped particles may be employed in
the present invention to form the underlayment.
Coating Application Methods
[0145] In further embodiments, the coatings are applied using
different application methods, which change the structure or
bonding strength of the underlayment. In one embodiment, one or
more suitable solvents or solvent-catalyst blends are sprayed or
applied to the bonding material layer on the substrate
simultaneously with the substantially uniform particles. The
resultant spray or application method appears as a type of atomized
spray, which enables the process to more completely wet the surface
of the substrate. This process creates an even stronger bond
between the bonding material layer and the uniform particles.
[0146] In another embodiment, a powder spray process is used, which
enables an operator to better control the application of the layers
to the substrate. The powder spray process applies the uniform
particles as very fine particles to the lower layers adhered to the
surface of the substrate. This process enables an operator to
control the density of each of the layers applied to the substrate
and also enables the operator to coat odd-shaped substrates with
more control and accuracy. In a further embodiment, the
electrostatic powder spray is used to apply a topcoat such as a
powder paint coating or fluoropolymer powder coating to the surface
of the substrate. In this embodiment, a bonding material and then a
conductive material or coating is applied to the surface of the
substrate. The powder coating is then cured in a convection or
infrared oven, and because the powder coating does not include
solvent, the heat from the oven heats and shrinks the powder
coating onto the top of the dry particles. This type of topcoat may
be used in many different industrial applications such as to
produce electrical characteristics or increasing abrasion
resistance of commercial bakeware and cookware.
[0147] In a further embodiment, electrostatic, tribo-charged or
opposite electrostatic charged powder technology is used to further
enhance the dry particle attachment or adherence to an odd-shaped
configuration. The dry particles may be electrically insulative,
but treated with a veneer of very thin conductive or insulative
materials, such as the materials sold by the Ransburg Corporation,
for creating electrostatic properties on substrates such as wood.
In one embodiment, the dry particles are "soaked" with these
electrostatic enhancing coatings or materials and subsequently
dried or applied in a wet state with more conventional spray gun
technology designed for wet materials. If the harder particles are
ceramic and the configuration is very odd and angular, such as a
fan housing or fan blades, electrostatic powder technology enhances
the distribution of the dry particles. The bonding material layer
or primer is altered to provide maximum electrical grounding
potential by using solvents that are electrically conductive and
contain water in some cases. This provides the maximum attraction
of the dry particles to the bonding material layer, which provides
a uniform, dense coating as desired by the application in all areas
of a vessel or industrial component, such as a fan blade as shown
in a centrifugal fan or turbine.
[0148] In the tribo-charging process, the tribo-charging is
accomplished by stripping the electron off a particle of powder.
This is accomplished by passing the particle over an opposite
charged material that strips the electron off which is passed to
ground or earth. This is commonly used by passing nylon particles
through PTFE tubes by using air pressure to move the nylon
particles at high surface speed over the PTFE surface. The opposite
holds true. If PTFE particles are passed over nylon surfaces, they
lose the outer layer of electron charge and are attracted to ground
or a grounded article or surface.
[0149] In another embodiment, the wet materials can be introduced
with conventional spray or electrostatic spray technology to apply
the bonding material layer or primer to a surface of a substrate.
In one example, a shaft, on which a wet bonding material layer is
applied, is rolled over an electrostatic, aerated, fluidized bed of
approximately 100,000 volts passing through an electrostatic grid
with the dry particles suspended over a porous membrane of
polyethylene. When air pressure is introduced underneath the
electrostatic grid in an open top container, the dry particles
become charged by the air passing through and past an electrical
grid, which is placed slightly below the insulated polyethylene
membrane. The charged dry particles above the porous polyethylene
membrane are uniformly attracted to the wet substrate on the
surface of the shaft, which is suspended and rotated above the
fluidized bed. Because of the self-limiting characteristics of the
electrostatic method, the dry particles are uniformly applied as
the particles are applied to the substrate. The applied dry
particles, as the particles are deposited, create an insulated
layer in the areas where the dry particles are attached or
attracted to the wet bonding material layer. This method provides a
very uniform application of the dry particles to the surface of the
substrate at high speeds and at low commercial costs.
[0150] In a further embodiment, the substantially uniform aluminum
oxide particles are applied to a surface of a substrate to achieve
a desired roughness on the surface. The desired surface roughness
is achieved by changing the size of the aluminum oxide particles
applied to the surface. The aluminum oxide particles are applied to
a thin bonding material layer on a surface of a substrate and
create a very strong bond with the surface of the substrate. The
aluminum oxide particles may be applied to various surfaces
including the surfaces of rigid parts. The application of the
aluminum oxide particles to roughen the surface or surfaces of a
substrate substantially minimizes the distortion to the surface,
which occurs with conventional blasting methods, and enables a user
to control the roughness of the surface. In addition, harder
particles such as boron nitride particles or other suitable
particles can be applied to the surface of the substrate to
increase the penetration resistance of the surface.
Selective Application of the Uniform Particles
[0151] The wet bonding material layers are generally applied to the
entire surface of a substrate. In one embodiment, the uniform
particles are applied onto the entire wet bonding material layer.
In another embodiment, the uniform particles are applied to
specific areas on the wet bonding material layer on the surface of
the substrate. In this embodiment, a mask of a suitable masking
material is applied to the wet bonding material layer to prevent
the adherence of the uniform particles to the masked areas. Thus, a
surface of a substrate such as a particular surface or portion of a
surface of a part can be masked or selectively coated with a
suitable masking material so that the dry uniform particles are
applied to specific areas of the surface of the substrate. In one
example, specific surfaces of a cooking pan such as a saute pan or
wok are selectively coated with a non-abrasive and/or non-stick
material to reduce abrasion and wear on those surfaces of the pan.
A metal utensil is commonly used to stir or mix food products in
the pan, which causes abrasion of the surfaces of the pan. The
abrasion is generally focused on the bottom surface of the pan and
not the side surfaces because the bottom surface of the pan gets
hot causing the food products to stick to the bottom surface.
Efforts of a user to dislodge the food product from the bottom
surface using a metal or similar utensil, concentrates the vast
majority of the wear on the bottom surface of the pan. Therefore,
to increase the abrasion resistance of the bottom surface of the
pan, a wet bonding material layer is applied to the entire cooking
surface of the pan followed by a selective application of abrasion
resistant particles, such as relatively hard particles, to the
bottom surface of the pan. This is accomplished by applying the wet
bonding material to all of the surfaces of the pan. Then, a mask or
suitable masking material, which does not allow the uniform
particles to adhere to or partially adhere to it, is applied to the
surfaces of the pan except the bottom surface of the pan. The
abrasion resistant particles therefore, will only adhere to the
bottom surface of the pan and not to the masked surfaces. In one
embodiment, the above applications are followed with a thin
application layer of smaller sized dry reinforcing particles to the
entire surface of the pan. In all cases, a topcoat including a
non-stick material is applied to the entire surface of the pan.
[0152] The present embodiment can also be used in industrial
applications to reduce cost and/or improve machine tolerances. In
one example, the cylindrical area and top of the valve are coated
with the wet bonding layer. A uniform dry particle layer is applied
by then inverting the solenoid valve so that the uniform dry
particles contact the sides of the cylindrical area of the solenoid
while it is being rotated. Gravity causes the excess dry particles
to drop down providing no dry particles that are adhered to the
bottom wet area of the valve of the solenoid. The solenoid surfaces
are then completely cured using a suitable curing process.
Subsequently, bronze particles are applied to the outside surface
of the cylindrical area and then covered with a thin, appropriate
topcoat. The face of end surface of the solenoid is only coated
with a single coating of the original wet bonding material layer,
which has been cured as described above.
Magnetic Particle Embodiment
[0153] In a further embodiment, dry magnetic particles are applied
to the wet surface of a glass or non-magnetic metal substrate to
completely coat the surface of the substrate. In one aspect of this
embodiment, a magnetic shape is placed on a surface to be coated,
either under, above or both under and above, the surface. The
magnetic shape may be any shape, symbol, character or other
suitable image. The shape will appear on the surface of the
substrate as the magnetic particles orient themselves due to the
magnetic forces attracting the magnetic particles while the
magnetic particles "float" in the liquid layer. A suitable
non-magnetic material, such as aluminum or glass, is used as the
substrate.
[0154] One example is a glass or metallic baking pan. A wet bonding
material is first applied to the surface. Magnetic particles, such
as magnetic stainless steel or magnetic iron particles that are
dry, are applied to the non-magnetic pan. The wet bonding layer
stays moist during this dry magnetic particle application phase. A
magnetic image, which might be a company logo, part number,
identification or other suitable identifier, is created with a
highly magnetic force field. This may be electromagnetic or
magnetic in nature comprising a predetermined shape. The magnetic
shape can be suspended below and in contact with the pan or it can
be suspended slightly above the surface of the magnetic particles,
not touching the particles. The magnetic forces will affect the
magnetic material that has been introduced as a dry particle to the
wet base bonding layer and the shape of the magnetic forces will be
shown in the pattern in the coating created by the orientation of
the metallic particles.
[0155] Various blends of metallic particles can be used and various
shapes can be blended into the dry layer so that very distinct
images appear in the layer depending on the formulations of the dry
particles. In one example, a coffee cup that has had a wet bonding
layer applied followed with an application of the dry magnetic
material can have a company logo created with an electromagnet or
solid magnets, such as Rare Earth or Alnico magnets, which will
orient the magnetic particles that have been introduced to the wet
bonding layer to create an image that is that of the company's
logo. It should be appreciated that the letters would be reversed,
in mirror images, if placed below the pan so that the viewing of
the pan from the topside, where the wet bonding/dry magnetic
particle layer is applied, reads correctly. This could be followed
immediately, while the magnetic forces are held in place, with a
semi-curing infrared heat cycle which would harden the wet bonding
layer so that the orientation of the magnetic particles while they
are being magnetized would hold the formed shape. In this
embodiment the magnetic particles may be ferrite particles, ferrous
particles, or any suitably magnetic materials, including stainless
steel. In one aspect of this embodiment, the magnetic particles are
densely packed at the surface due to the forces the magnetic field
places upon the particles at the surface and on the surface of the
substrate. The magnetic contraction or alignment occurs within the
wet bonding layer while the magnetic particles "float" before the
wet bonding layer is hardened through a curing operation.
[0156] In a further embodiment, ferrite particles are applied to
the surface or surfaces of a substrate over a wet bonding material
layer to absorb microwaves or similar waves such as in a microwave
oven. For instance, the ferrite particles may be applied to a wet
bonding material layer on a glass container. This step is repeated
several times until the ferrite particles, which are chosen for
their microwave absorptive capabilities, have sufficient depth to
create and transfer energy in the form of heat to food products
inside the glass dish while in a microwave oven. In this
embodiment, the entire glass dish or bowl would be coated with the
wet bonding material layer, which would be opaque in nature. The
ferrite particles are introduced only to the bottom of the dish.
This would allow, when the complete system is cured, for the
microwave energy to be absorbed in the center of the dish. For
example, a microwave popcorn maker could be made in such a manner
in which the heat was concentrated at the bottom of the microwave
vessel, container or dish allowing the newly popped corn to leave
the hot surface and be replaced by heavier and denser popcorn as it
falls into the center of the curved dish. In another example,
medical sterilization equipment could be manufactured with plastic
and the bonded ferrite layer, which would produce localized heat in
certain areas of the plastic as determined by the introduction of
the ferrite particles where necessary.
[0157] In a further embodiment, the coated substrate is cured using
induction heating. In this embodiment, induction or magnetic
sensitive particles such as uniform metal particles are applied to
the wet bonding material on the surface of a substrate. The metal
particles may include uniform magnetic stainless steel flakes or
stainless steel particles. The flakes or particles are rearranged
in the wet bonding material using a magnet or other suitable
magnetic device. Induction waves, which are reverse magnetic
fields, are then directed at the coated substrate to induce heat in
the wet bonding material. The heat induced in the wet bonding
material cures the wet bonding material to produce the final coated
substrate. In another embodiment, an induction heat device is used
to raise the temperature of the substrate and thereby cure the wet
bonding material layer.
Density of Uniform Particle Layer
[0158] In a further embodiment, the strength of the bonds and the
layers on the substrate are increased by increasing the density of
the uniform dry particles that are applied to the bonding material
layer on the surface of a substrate. In one aspect of this
embodiment, commercial, unmodified or modified grit blasting or
sandblasting equipment is employed to apply the dry particles to
the bonding material layer. The density of the particles in the
bonding material layer is increased by increasing the pressure of
the spray and the velocity of the dry particles and the rate of
speed in which the coatings are applied to the bonding material
layer. The increased pressure of the dry particle depositing spray
and the rate at which the dry coating or dry coatings are applied
to the bonding material layer, increases the packing or density of
the particles in the wet bonding material layer. The pressure of
the spray and/or the rate of speed of the spray may be adjusted to
maximize the density of the dry particles based on the desired
design specifications.
[0159] The high-speed introduction of particles into the bonding
material can also be used when multiple-sized dry particles are
applied to the surface of a substrate. In one example, a first
layer includes relatively small particles of approximately 20-50
microns, followed by the application of relatively large particles
of approximately 150 microns followed by the application of
relatively small particles of approximately 20-50 microns followed
by the application of smaller particles of approximately 10-20
microns. In this embodiment, the density of a 30-40 micron wet
bonding material layer is increased and also the interconnectivity
or contact between particles is enhanced. This layer, when wet,
will be 30 microns, but the finished layer may actually be greater
with the 150-micron particles protruding from the surface and
causing the surface of the substrate to be slightly textured.
Particle Encapsulation
[0160] In an alternative embodiment, the substantially uniform dry
particles are pre-treated, encapsulated or micronized with a wet
bonding material such as an adhesion promoting encapsulent or
catalytic reactive material producing encapsulent prior to being
applied to the wet surface on a substrate. One example of an
adhesion promoting encapsulant is a silane coupling agent or
silane. The wet bonding material applied to the dry particles may
be the same or different from the wet bonding material applied to
the surface of the substrate as described above. Preferably, the
bonding material is compatible with the bonding material layer
applied to the surface of the substrate and any other coating
layers applied to the substrate. In one embodiment, the particles
are placed in a rotary device such as a tumbler. The bonding
material is sprayed or applied as droplets into the tumbler and
thereby evenly distributes and coats the dry particles as the
particles rotate in the tumbler. The bonding material basically
coats all of the areas of the dry particles with a thin veneer. The
coated particles are dried or semi-cured to encapsulate the dry
particles, and then applied to the wet bonding material layer.
[0161] In one embodiment, a curing cycle is employed to semi-cure
the wet bonding agent or bonding material, which contains a resin
and a solvent to the once dry particles. The extra curing process
enables the dry particles to adhere to each other and also
evaporates or removes the solvent from the base or initial coating
layer, which strengthens the bond between the dry particles and a
intermediate or lower layer on a surface of a substrate. Thus,
pre-coating or pre-treating the dry particles with a bonding
material enhances the bonding capabilities of the particles to each
other and enhances the bonding strength between the particles and
the bonding material layer on the surface of the substrate and
subsequent applied layers.
Wave Absorption Embodiment
[0162] In one embodiment, the present method is used to attenuate
or absorb magnetic, electromagnetic, radio or other airborne waves
or signals such as in a medical X-ray room or similar area such as
in RF shielding. Currently, sheets of metal such as copper or
similar materials are used to cover the surfaces in these areas. In
the present method described above, a wet bonding material is
applied or sprayed onto a vertical or horizontal surface or
substrate such as a wall or floor in a room. In this embodiment, it
should be appreciated that the base material layer such as the
bonding material layer may have a thickness of approximately
125-150 microns.
[0163] After the wet bonding material is applied to the surface or
surfaces, a suitable magnetic wave or other suitable absorbing type
material such as dry copper particles, which may have a thickness
of approximately 50-75 microns, are applied to the wet bonding
material layer. These relatively smaller particles fill in the
areas that are still wet between the larger particles.
Additionally, a leafing material such as silver, nickel, copper,
bronze, or any other conductive material may be applied to the
uniform dry particles. Once the coated substrate is grounded using
the leafing material, the entire exposed surface acts as an
electrical conductor such as a sheet of metal. Thus, additional
layers can be added to the multiple layers of the original
formulation of primer or bonding material. The sequence can be
repeated until the thickness of the layers is approximately 400-500
microns or greater. The multiple sized particles in this
underlayment contact each other interconnectedly to provide an
essentially impermeable barrier to radio waves or any other
airborne electromagnetic or electronic waves.
[0164] The benefit of the underlayment including the wave reducing
or absorbing layer is that the metallic particles are densely
compacted into the wet bonding material layer. In conventional
coating processes, the particles are applied to the surface of a
substrate as a part of the wet coating and therefore, the coating
may actually prevent contact between the particles. Conversely,
careful formulation of the bonding material layer actually produces
a shrinking or cohesive effect which increases the density of the
layers as the layers are dried or catalyzed in place.
[0165] Thus, the present invention enables the dry copper particles
to completely cover the desired surfaces and thereby minimize or
eliminate the gaps and seams produced by conventional methods,
which cover or line walls in a room with sheet of metal such as
copper. Additionally in one embodiment, a flexible bonding material
is used to enable the coatings to better adhere to the surfaces,
twists and bends of the surfaces such as corners in a room. In one
aspect of this embodiment, to enhance the adherence and coverage of
the particles to the bonding material layer, an electrically
conductive bonding material is used to attract the oppositely
charged particles.
[0166] In RF shielding on plastic, many materials have been used
which contain leafing particles of copper, bronze, and other
similar materials to provide a metallic shield over plastic parts.
In all cases, these liquid coatings with high-solids metals had
problems with distribution of the particles because of the settling
characteristics of the heavy metals, particularly the copper and
bronze. Also, the uneven distribution of particles caused the
particles to remain substantially separated by the carrier resin,
which negatively affects the conductivity of the coating. Thus, the
coatings must be applied thicker and thicker to minimize or
eliminate the voids or separation of the particles in the coating
where radio waves or electromagnetic waves may permeate an opening
in the coating or coatings.
Adhesives
[0167] In one embodiment of the underlayment of the present
invention, the materials can be more effectively bonded to the
plastics using two-part adhesives, such as epoxy and urethane and a
very dense metallic layer, which would include pure metal
interconnecting metallurgically with intimate particle-to-particle
contact. In this embodiment, the impingement velocity of the dry
particles sprayed onto the wet bonding material causes the dry
particles to stick to the bonding material layer, which provides a
dense particle layer. The density of the particle layer may be
increased by using multi-sized and multi-shaped particles. The dry
particle layer can be electrically tested before further coatings
are applied to the dry particle layer. This enables a user to be
able to test the conductivity of the coatings before additional
layers are applied and also enables the user to reinforce a section
or area of the underlayment with more particles, if more particles
are needed based on the conductivity.
INDUSTRIAL APPLICATIONS
[0168] In another embodiment, industrial sifters, strainers,
filters and similar industrial components, which are comprised of
thick plates with perforated holes, are completely coated with wear
resistant coating using the underlayment of the present invention.
For example, commercial laundry dryers used in hospitals can be six
feet or greater in diameter and ten feet or longer, comprising of
several curved plates bolted to a structure, which resembles a drum
when complete. In this case, the scraping of clothing and plastic
items against the non-stick surface or surfaces of the dryers wears
the surfaces away. Using the underlayment of the present invention,
the non-stick surfaces of the dryers is substantially strengthened
and the wear resistance of these surfaces is significantly
enhanced.
[0169] In another example, a surface or surfaces of industrial
centrifuges are coated. Industrial centrifuges incur great wear
during operation. With conventional technology, hard particles such
as stainless steel particles are made molten and directed towards a
surface or surfaces of a substrate such as by using an arc spray or
plasma detonation with detonation gun technology, to increase the
roughness of the surface or surfaces. This application method,
however, typically coats the surface or surfaces which are at right
angles to or directly impacted by the spray, but fails to
completely coat the inside surfaces of vertical holes which are on
surfaces parallel to the direction of the spray.
[0170] In the embodiment of the present invention, by using
electrostatic spray technology to apply the bonding material layer
to the surface or surfaces of the substrate, the uniform dry
particles completely cover the flat surface of the inside of the
centrifuge, but also, all of the holes that allow media to pass
through the centrifuge. By using this electrostatic combination of
liquid and subsequent powder-spray application, the inside surface
which defines the holes are strengthened through the uniform
application of the wear resistant dry particles. Present technology
does not strengthen the inside surfaces of the holes. Thus, in
conventional centrifuges, the media passing through the holes
eventually wears away the soft non-stick coating on the surface or
surfaces of the surfaces of the centrifuges. With the present
invention, the flat surface and the surface which defines the holes
are completely coated and protected. This is substantially
different than the conventional technology in that the distribution
of the wear-resistant particles in the conventional technology is
focused on the flat surfaces and does not completely coat the
surfaces. With the present method, the electrostatic attraction of
the particles to the wetted surfaces, ensures complete coverage of
the bonding material layer to the flat surfaces and the holes.
[0171] In a further embodiment, the present invention is employed
in a rotary molding system such as a reactor or commercial dryer
vessel to improve the wear resistance of the system. The
predetermined quantity of bonding material is filled into the
vessel such as the reactor cavity or main dryer compartment and
rotated in a multi-directional manner to completely and uniformly
coat the inside surface of the vessel. Then, suitable substantially
uniform abrasive-resistant particles or other suitable particles
are filled into the vessel and are applied to the bonding material
layer on the inside surface of the vessel using the
multi-directional rotation of the vessel described above. After the
dry particles coat the surface, the vessel is inverted and the
excess particles drop out of the vessel. The bonding material and
dry particles on the surface are cured using a suitable curing
process and a final coating or topcoat is then applied to the
uniform particle layer if desired.
[0172] In one example, a powder fluoropolymer topcoat, such as PFA
or FEP includes a combination of either a resin with PTFE and/or
any suitable and appropriate modifiers and strengthening agents,
such as graphite, talc, and lead powder. The underlayment is
created and cured at a temperature of approximately 750 degrees
Fahrenheit or lower, depending on the bonding resin or material
that is used in the process. The fluoropolymer-rich topcoat, which
is in powder form, is applied to the underlayment for wear
resistance, if necessary, such as in a machine channel or guide or
commercial baking pan or similar bakery or food processing
equipment.
[0173] The underlayment, if it consists of aluminum oxide or
similar abrasion-resistant particles, which are very hard, is
coated with the fluoropolymer powder mixture and FDA or food
contact ingredients are selected to comply with FDA requirements.
This allows the creation of a highly wear resistant, non-stick
coating with a powder topcoat.
[0174] In another example, preparation for arc spraying stainless
steel wire and titanium wire, to create a bumpy or rough base
requires an extensive amount of grit blasting and surface
preparation to roughen the surface for the mechanical grip such
that these dissimilar metals, when impinged in a molten state on
the surface, cannot bond metallurgically. With the underlayment of
the present invention, the dry uniform particles are bonded and
tightly adhered to a surface of a substrate through contemporary
adhesive technology and function at and beyond the temperature
constraints of typical topcoatings, such as PTFE, which has a limit
of approximately 550 degrees Fahrenheit. In other words, the
adhesive bond strength and temperature capacity of the underlayment
is greater than the temperature capacity of the subsequently
applied topcoat layers or topcoats.
Multiple Coating Applicators
[0175] In an alternative embodiment, a coating system includes a
plurality of coating or material applicators, at least one
container having a wet bonding material, at least one container
having substantially dry particles, wherein the containers are
connected to the coating applicators using at least one coating
line or tube, which transports the materials from the containers to
the coating applicators. It should be appreciated that the coating
applicators may be spray guns, electrostatic spray guns, powder
spray guns or any other suitable applicators. The coating
applicators are positioned adjacent to the surface or surfaces
being coated on the substrate.
[0176] In one aspect of this embodiment, one of the coating
applicators applies the wet bonding material to the surface of the
substrate and the other coating applicator applies an even,
substantially uniform layer of the dry particles to the wet bonding
material layer. The applicators may apply the coatings at the same
rate or at different rates. The coating applicators apply each
layer to the surface of the substrate until a desired thickness is
achieved.
[0177] In one example, the coating system includes multiple coating
or material applicators such as two electrostatic spray guns or
powder spray guns, to apply an epoxy-based material to a surface of
a substrate. The epoxy is made up of relatively dry particles which
are applied using electrostatic attraction to the surface. While
the dry epoxy is in place, a thin layer of a wet bonding material
is fog-sprayed or applied to the dry epoxy particles to slightly
dampen the surface of the particles. Then, a powder spray of
aluminum oxide, bronze, ceramic, glass or any other suitable
material is applied to the bonding material on the particles. The
layers are then heated or cured. Subsequently, a final coating such
as a wet or dry film, may be applied to the cured layers. In one
example, an epoxy base is applied to the surface of the substrate.
Then, a wet film including a solvent and water is applied to the
epoxy to wet the epoxy and provide some stickiness on the surface.
A dry powder spray of non-electrostatic particles are then applied
to the surface.
[0178] It should be appreciated that the underlayment of the
present invention can be used as a single process without any
topcoats to provide adhesion of paper or grip or tractive strength
as related to moving paper or other products with a roller at high
speeds. Additionally, the underlayment could be created with
approximately 30 to 40 micron thick bonding material layer and an
approximately 200-micron sharp particles of aluminum oxide or boron
nitride or other very high-wear resistant ceramics and provide an
abrasive gripping surface.
[0179] It should be understood that various changes and
modifications to the presently preferred embodiments described
herein will be apparent to those skilled in the art. Such changes
and modifications can be made without departing from the spirit and
scope of the present invention and without diminishing its intended
advantages. It is therefore intended that such changes and
modifications be covered by the appended claims.
* * * * *