U.S. patent application number 16/165474 was filed with the patent office on 2019-02-14 for application of polymer thermofoil to metal substrate.
The applicant listed for this patent is Midmark Corporation. Invention is credited to Alan Heitkamp, Duane Rieman, Linda Steinbrunner, Scott Strait.
Application Number | 20190047275 16/165474 |
Document ID | / |
Family ID | 64316155 |
Filed Date | 2019-02-14 |
United States Patent
Application |
20190047275 |
Kind Code |
A1 |
Strait; Scott ; et
al. |
February 14, 2019 |
APPLICATION OF POLYMER THERMOFOIL TO METAL SUBSTRATE
Abstract
The present invention is directed to a novel method for
application of polymer thermofoil to a metal substrate. The method
involves first coating a metal substrate with an
oxidation-preventing or oxidation-limiting coating, then adhering a
polymer thermofoil to the metal substrate. After application of the
thermofoil, the metal substrate can be formed to the final shape.
The method is advantageous in that it allows one to efficiently
manufacture metal objects in a variety of aesthetically pleasing
surface finishes.
Inventors: |
Strait; Scott; (Greenville,
OH) ; Heitkamp; Alan; (Maria Stein, OH) ;
Rieman; Duane; (Versailles, OH) ; Steinbrunner;
Linda; (Fort Recovery, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Midmark Corporation |
Versailles |
OH |
US |
|
|
Family ID: |
64316155 |
Appl. No.: |
16/165474 |
Filed: |
October 19, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14985962 |
Dec 31, 2015 |
10137675 |
|
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16165474 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B32B 38/0012 20130101;
B29L 2009/001 20130101; B29C 66/71 20130101; B29K 2027/06 20130101;
B32B 37/1207 20130101; B29C 66/742 20130101; B29C 66/7392 20130101;
B29C 66/47 20130101; B32B 2037/1215 20130101; B29C 69/007 20130101;
B29K 2305/00 20130101; B29K 2105/0097 20130101; B29C 66/1122
20130101; B32B 2255/06 20130101; B21D 22/00 20130101; B29C 66/034
20130101; B29C 51/16 20130101; B32B 2327/06 20130101; B29C 65/48
20130101; B29C 66/71 20130101; B29K 2027/06 20130101 |
International
Class: |
B32B 37/12 20060101
B32B037/12; B32B 37/10 20060101 B32B037/10; B29C 65/00 20060101
B29C065/00; B29C 51/08 20060101 B29C051/08 |
Claims
1. A method for manufacturing a thermofoil covered metal substrate,
the method comprising the steps of: coating at least one surface of
a metal substrate with an oxidation-preventing or
oxidation-limiting coating; applying adhesive to at least one
surface of the coated metal substrate, applying a thermofoil sheet
to the adhesive, thus causing the thermofoil sheet to adhere to the
metal substrate; and forming the metal substrate into a desired
final shape.
2. The method of claim 1 wherein the adhesive applied to the at
least one surface of the coated metal substrate comprises a hot
melt adhesive.
3. The method of claim 1 wherein the method further includes a
final step of heating the metal substrate after the step of forming
the metal substrate into a desired final shape.
4. The method of claim 1 wherein the oxidation-preventing coating
comprises a powder-based coating.
5. The method of claim 1 wherein the thermofoil sheet comprises
polyvinyl chloride.
6. The method of claim 1 wherein the step of forming the metal
substrate into a desired final shape is accomplished using a press
brake.
7. A method for manufacturing a thermofoil-covered metal substrate,
the method comprising the steps of: producing a metal blank;
coating at least one surface of the metal blank with an
oxidation-preventing or oxidation-limiting coating; applying
adhesive to at least one surface of the coated metal blank;
applying a thermofoil sheet to the adhesive, thus causing the
thermofoil sheet to adhere to the metal blank; trimming any excess
thermofoil from the metal blank; and forming the metal blank into a
desired final shape.
8. The method of claim 7 wherein the adhesive applied to the at
least one surface of the coated metal substrate comprises a hot
melt adhesive.
9. The method of claim 7 wherein the method further includes a
final step of heating the metal blank after the step of forming the
metal blank into a desired final shape.
10. The method of claim 7 wherein the oxidation-preventing coating
comprises a powder-based coating.
11. The method of claim 7 wherein the thermofoil sheet comprises
polyvinyl chloride.
12. The method of claim 7 wherein the step of forming the metal
blank into a desired final shape is accomplished using a press
brake.
13. A method for manufacturing a thermofoil-covered metal
substrate, the method comprising: coating at least one surface of a
metal sheet with an oxidation-preventing or oxidation-limiting
coating; applying adhesive to the oxidation-preventing or
oxidation-limiting coating; applying a thermofoil sheet to the
adhesive, thus causing the thermofoil sheet to adhere to the metal
sheet; cutting the thermofoil-covered metal sheet to a shape
conducive to forming the metal sheet to a desired final shape; and
forming the cut metal sheet into a desired final shape.
14. The method of claim 13 wherein the adhesive applied to the
oxidation-preventing or oxidation-limiting coating comprises a hot
melt adhesive.
15. The method of claim 13 wherein the method further includes a
final step of heating the formed metal sheet after the step of
forming into a desired final shape.
16. The method of claim 13 wherein the oxidation-preventing coating
comprises a powder-based coating.
17. The method of claim 13 wherein the thermofoil sheet comprises
polyvinyl chloride.
18. The method of claim 13 wherein the step of forming the metal
blank into a desired final shape is accomplished using a press
brake.
Description
CLAIM OF PRIORITY
[0001] This application claims priority to U.S. 62/099,163.
BACKGROUND AND BRIEF SUMMARY OF THE INVENTION
[0002] The present invention is directed to a novel method for
making metal cabinetry and other metal objects more aesthetically
pleasing to the end user. More particularly, the present invention
involves the application of thermofoil surface finish to metal
substrate as will be described in greater detail below.
[0003] Thermofoil surface finish is well known in the cabinetry
industry, so will not be discussed in detail herein. However,
briefly stated, thermofoil is a thin polymeric material (commonly a
plasticized polyvinyl chloride) that is thermoformed, under vacuum
pressure to a substrate, thus giving the substrate a durable top
coat or surface finish. Thermofoil comes in a number of finishes,
including high and low sheen, metallic-like finishes and faux wood
grain finishes. The process of applying thermofoil generally
involves the steps of (1) preparing the substrate, (2) applying
adhesive to the substrate and/or thermofoil, (3) placing the
thermofoil layer over the substrate, and (4) heating the thermofoil
while under vacuum to cause the thermofoil to stretch and form to
the underlying substrate (normally accomplished using a vacuum
membrane press). Up to this point, thermofoil has generally been
applied to various wood-based surfaces since wood is easily
contoured and shaped. However, the present invention discloses a
novel method that allows the application of thermofoil to an
unformed metal substrate that can then be subsequently formed to a
final product, thus resulting in a more aesthetically pleasing
outcome.
[0004] As just mentioned, thermofoil is most commonly applied to a
wood or fiberboard substrate. More particularly, it is frequently
applied to medium density fiberboard (MDF). Fiberboard lends itself
well to such applications because it can be easily milled to
different profiles over which the thermofoil can be applied. Thus,
when used in cabinetry applications, a faux wood grain thermofoil
can be used to give the appearance of milled solid wood cabinetry
at significantly reduced cost. The same is likewise true if a solid
colored thermofoil is used--it gives the appearance of painted
solid wood, but provides a much more durable finish than a painted
surface, and can generally be done at a lower cost.
[0005] In contrast to wood-based substrates, working with
thermofoil on metal substrates can be difficult for a number of
reasons. Often, pre-formed or pre-machined metal substrates are
shaped in such a way that it is impossible to apply thermofoil to
the part, or even if thermofoil can be applied to the part, it is
simply not practical to place these parts in the vacuum membrane
press during the thermofoil application process. In addition,
because these parts are metal, they often have sharp edges that can
easily damage the vacuum membrane press during thermofoil
application. Because of these and other issues, thermofoil has
historically not been used in applications in which it is applied
to a metal substrate. Rather, paints, powder coatings, and the like
have become the standard coating or covering used in finishing
metal surfaces.
[0006] In certain heavy-use applications, it is often beneficial to
construct cabinetry out of metal. One preferred metal for use in
manufacturing metal cabinetry is steel, although aluminum or other
metals or alloys could be used in other embodiments of the present
invention. Steel provides superb durability as well as excellent
strength when compared to its weight. However, in certain
applications the aesthetic appeal of steel cabinets finished in a
single color paint or powder coat finish is not ideal. To address
this, manufacturers have previously offered cabinetry comprising a
steel cabinet body with cabinet doors made of MDF finished with a
faux wood grain thermofoil. The thermofoil cabinet doors in
combination with an appropriate countertop allows the cabinet to be
much more aesthetically appealing, yet still sufficiently durable
for heavy-use applications. While such an arrangement offers clear
advantages, it does not fully eliminate aesthetic concerns, as the
metal body of the cabinet is still unable to be offered in more
aesthetically pleasing finishes such as faux wood grain or other
finish selected to match accompanying cabinet doors.
[0007] The present invention addresses this need by providing a
method of applying thermofoil to a metal substrate to produce an
aesthetically pleasing result while also remaining relatively easy
to apply and process.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 Flowchart depicting the steps involved in one
preferred embodiment of the present invention.
[0009] FIG. 2 A cross-section of the finished product of one
preferred embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0010] The present invention is directed to a novel process for
applying thermofoil to a metal substrate. More specifically, the
present invention is directed to application of thermofoil to a
painted, or coated, metal substrate.
[0011] While the present invention is primarily focused on the use
of thermofoil-coated metal substrates in cabinetry, it will be
understood that the methods described herein can also be used in
non-cabinetry applications, such as in automotive accessories,
other household accessories, or other instances in which a
thermofoil-coated metal substrate would beneficially provide both
aesthetics and durability.
[0012] Turning now to a description of FIG. 1, there is shown a
flow chart depicting one preferred method of performing the process
of the present invention. Each of the steps involved in the flow
chart will be described in greater detail below, including
variations of these steps that also fall within the scope of the
present invention.
[0013] In box 100, an initial metal blank is produced. By producing
a metal blank it is meant that stock metal material (e.g., steel
sheets or other similar starting material) is cut into the desired
initial shape. In the case of using metal sheets as the starting
material, a blank can be cut from the sheets, with the blank
including holes and other cutouts required for the part to have the
correct shape and features once it reaches its final form. For
example, holes may be cut in the flat sheet for later use in
mounting hinges or other cabinetry hardware, mounting a shelf, or
interlocking with other cabinet pieces. Alternatively, a metal
blank can comprise a single flat sheet that is cut to final shape
after the application of a polymer thermofoil to the flat sheet.
However, it will be understood that at this step the metal blank
remains flat and is not formed other than being cut. The cutting of
the metal blank can be accomplished using any methods commonly
known in the art (e.g., plasma, press cutting or stamping,
etc.)
[0014] Once the initial metal blank is produced it is then coated
102. By coated it is meant that the metal blank is covered on at
least one surface with some form of oxidation-preventing or
oxidation-limiting coating. Such coatings are well known in the art
and include solvent-based coatings, such as paints and epoxies, and
dry coatings such as powder-based coatings that are heated after
application to form a uniform surface covering. In one preferred
embodiment, the metal blank is fully covered with a powder coating
during this step. The advantages of powder coating are many and are
well known in the art, so will not be discussed in detail herein.
However, it will be noted that in undergoing the coating process,
the coating used will preferably have an elastic modulus of low
enough value to allow the metal blank to later undergo bending
without the coating developing cracks or other imperfections.
Likewise, the adhesive properties between the coating and the metal
will also preferably be of sufficient strength to allow the metal
blank to be bent and formed after coating without causing
detachment of the coating.
[0015] It will be understood that the process of coating the metal
blank also provides aesthetic benefit. Specifically, while the
outer surface of the metal blank will eventually be covered with
thermofoil, fully coating the metal blank prevents any unfinished
edges, inner surfaces, or other bare metal surfaces from showing in
the final product and also prevents oxidation of the underlying
metal substrate, thus providing a more aesthetically pleasing final
product.
[0016] Once the metal blank is coated, a layer of adhesive is
applied to at least one surface of the metal blank 104.
Specifically, the adhesive is preferably applied to the surface to
which the thermofoil will be affixed. The adhesive can be a hot
melt adhesive, solvent based adhesive, or other standard adhesive
known in the art. One common adhesive used in such applications is
a polyurethane-based moisture reactive curing hot melt adhesive. In
one preferred embodiment of the present invention a
pressure-sensitive hot melt adhesive is used. Application of the
adhesive can be performed using techniques known in the art such as
direct application using a brush or other applicator or by use of a
sprayer to apply an even coat of adhesive through aerosolization
and subsequent deposition on the desired surface. However, as with
the step of coating the metal substrate, the adhesive preferably
has elastic properties that allow it to undergo bending and forming
without losing adhesion or failing in some other manner.
[0017] After application of the adhesive, a sheet of thermofoil
covering is applied to the surface of the metal blank 106 on which
the adhesive was applied in the prior step. The thermofoil is then
adhered to the surface of the metal blank. As noted above, in one
preferred embodiment of the present invention, a pressure sensitive
hot melt adhesive is used to bond the thermofoil to the metal
blank. In this case the metal blank is heated and pressure is
applied in order to attach the thermofoil to the metal blank.
Because the metal blank is still flat during this step, a vacuum
membrane press is unnecessary since there are no surface contours
on the metal blank to which the thermofoil needs to conform.
Rather, a roller, a press, or other similar apparatus can be used
to apply pressure to the thermofoil to ensure that proper adhesion
occurs. This also provides efficiency in manufacturing since such
an approach eliminates the need for a manufacturer to invest in a
vacuum membrane press. It will be understood, however, that in
certain embodiments of the present invention the metal blank may
have certain surface contours formed in the metal through the use
of presses, dies, etc., and in these instances a vacuum membrane
press could be required to ensure that the thermofoil becomes
properly attached to the underlying metal blank.
[0018] As with the above-noted coating, the thermofoil preferably
exhibits mechanical properties that allow it to undergo bending and
forming without cracking or otherwise detaching from the underlying
metal blank. Specifically, the thermofoil preferably has an elastic
modulus of low enough value to allow it to later undergo bending to
angles greater than 90 degrees without the thermofoil developing
cracks, but high enough that the thermofoil does not easily take on
permanent impressions or other surface imperfections from the
forces involved in being in contact with the forming equipment used
to shape the metal blank into its final form.
[0019] Once the thermofoil has been adhered to the surface of the
metal blank, the excess thermofoil must be trimmed 108 from the
edges as well as any needed openings included in the metal blank
(e.g., a slot or hole used for supporting a shelf after assembly).
The trimming process can be done manually or with the use of
automated equipment set to properly index and trim each metal
blank. Methods for trimming excess thermofoil are well known in the
art and will thus not be addressed in further detail herein.
Alternatively, if the metal blank from step 100 is simply a flat
sheet that has been fully coated with thermofoil, the trimming
process of step 108 can comprise the cutting of both the thermofoil
and metal blank to the final dimensions prior to forming.
[0020] Up to this point in the process, it will be noted that the
metal blank, or metal substrate, comprises a flat, or
2-dimensional, object. However, after the trimming step 108, the
forming process is begun 110. Through use of press brakes and other
metal forming tools and equipment known in the art, the metal blank
is formed into its final 3-dimensional shape, with care being taken
not to damage the softer thermofoil covering during the forming
process. Final shape can vary widely depending on the final
structure needed and the mechanical strength needed when the metal
blank is assembled as part of the final product Critically,
however, it has been observed that during the forming process the
thermofoil will develop stress markings indicated by a whitening of
the thermofoil covering near, or over, the point(s) where the metal
blank is bent or otherwise formed. This whitening is the result of
the applied stress causing shifting of the molecular bonds of the
thermofoil. This phenomenon is often referred to as crazing. This
whitening is not desirable from an aesthetic standpoint as it
causes inconsistencies in the finish of the final product. To
address this whitening, the method of the present invention
includes the step of heating the metal blank after forming 112.
This heating allows the local stress causing the whitening of the
thermofoil to be relieved and thus eliminates the stress whitening,
returning the thermofoil to its original finish. Heating is
preferably done to a point below the melting point of the
thermofoil and to a temperature relatively near to, or higher than
the glass transition temperature of the thermofoil. In an
alternative embodiment of the present invention, the
thermofoil-covered metal blank may be heated during the forming
process as a way of eliminating or reducing the occurrence of
stress whitening during the forming process. In still another
alternative embodiment, the color of the thermofoil can be such
that the stress whitening does not aesthetically affect the final
product, or the thermofoil can be formulated to withstand bending
with minimal or no stress whitening in either case, it will be
understood that heating of the thermofoil blank would be
unnecessary under these circumstances and that such a step could
then be omitted from the method.
[0021] Once the stress whitening has been eliminated (if present),
the metal blank is considered finished 114. If the metal blank is a
smaller part of a larger final product, it can then be assembled as
part of the final product.
[0022] Turning now to FIG. 2, there is shown a cross section of a
completed metal blank 128. It will be noted that FIG. 2 is not
drawn to scale. As illustrated in FIG. 2, a metal substrate 120 is
coated with an oxidation-preventing or oxidation-limiting coating
122. As mentioned above, such coatings are well known in the art
and include solvent-based coatings, such as paints and epoxies, and
dry coatings such as powder-based coatings that are heated after
application to form a uniform surface coating. An adhesive layer
124 is also shown, bonding the thermofoil 126 to the coated metal
substrate 120, 122.
[0023] While the above description has focused primarily on
application of polymer thermofoil to a precut metal blank, it will
also be understood that in other embodiments of the present
invention entire sheets of stock material could be covered with
thermofoil using the above process and then subsequently cut into
appropriate blanks for later forming into finished parts as already
mentioned above.
[0024] It will be apparent to those skilled in the art that various
modifications and variations can be made to the present invention
without departing from the spirit and scope of the invention as set
forth in the above description. Thus, it is intended that the
present invention cover the modifications and variations of this
invention provided they come within the scope of the invention and
its equivalents.
* * * * *