U.S. patent application number 10/151506 was filed with the patent office on 2003-11-20 for scratch resistant thermoplastic article.
Invention is credited to Horwitz, David James.
Application Number | 20030215607 10/151506 |
Document ID | / |
Family ID | 29419441 |
Filed Date | 2003-11-20 |
United States Patent
Application |
20030215607 |
Kind Code |
A1 |
Horwitz, David James |
November 20, 2003 |
Scratch resistant thermoplastic article
Abstract
A process and resulting thermoplastic article is provided
suitable for use in constructing furniture. The thermoplastic
article contains hardened particulates such as powders of alumina
oxide which brings about an improved cut and scratch resistance to
the surface of the articles. The hardened particulates may be
integrally mixed with the extruded product or applied post-molding
to a surface of the shaped article.
Inventors: |
Horwitz, David James;
(Savannah, GA) |
Correspondence
Address: |
J Bennett Mullinax
Robertson & Mullinax LLC
P O Box 26029
Greenville
SC
29616-1029
US
|
Family ID: |
29419441 |
Appl. No.: |
10/151506 |
Filed: |
May 20, 2002 |
Current U.S.
Class: |
428/141 ;
264/131; 264/211; 264/293 |
Current CPC
Class: |
Y10T 428/24355 20150115;
B29K 2995/0072 20130101; Y10T 428/252 20150115; B29K 2995/0087
20130101; C08K 7/16 20130101; Y10T 428/31855 20150401; B29C 48/08
20190201; Y10T 428/24372 20150115; Y10T 428/25 20150115; Y10T
428/2993 20150115; C08K 3/013 20180101; B29C 59/002 20130101; Y10T
428/259 20150115; B29C 70/64 20130101; B29C 59/04 20130101; B29C
48/022 20190201; B29K 2105/16 20130101; B29C 48/12 20190201 |
Class at
Publication: |
428/141 ;
264/131; 264/293; 264/211 |
International
Class: |
D06N 007/04 |
Claims
That which is claimed is:
1. A process of providing a wear resistant coating to a
thermoplastic article comprising the steps of: providing a
thermoplastic article having a surface temperature heated to a
softening temperature; applying an effective amount of a
particulate to a surface of the article, said particulate imparting
wear resistant properties to the surface of the thermoplastic
article, mechanically pressing the particulate-containing surface
with a pressure of about 150 to about 200 pounds per linear inch;
and allowing said thermoplastic article to cool.
2. The process according to claim 1 wherein said step of applying
an effective amount of a particulate further comprises supplying
said particulate at a concentration of about 1 to about 25 grams
per square meter.
3. The process according to claim 1 wherein said particulate is
selected from the group consisting of silicates, silica oxide,
fumed silica, alumina, alumina oxides, ceramics, and combinations
thereof.
4. The process according to claim 1 wherein said particulate has an
average particle diameter of between about 4 to about 10
microns.
5. The process of forming a thermoplastic extruded sheet having a
wear resistant surface comprising the steps of: providing a
thermoplastic sheet; embossing a surface of said thermoplastic
sheet, thereby imparting a matte finish to the sheet, the matte
finish comprising a series of elevations and depressions; warming
the matte surface to a softening temperature; applying a plurality
of hardened particulates onto the matte surface; and applying
pressure to the matte surface and the particulates, thereby
embedding the particulates into the matte surface.
6. The process according to claim 5 wherein said step of applying
an effective amount of a particulate further comprises supplying
said particulate at a concentration of about 1 to about 25 grams
per square meter.
7. The process according to claim 5 wherein said particulate is
selected from the group consisting of silicates, silica oxide,
fumed silica, alumina, alumina oxides, ceramics, and combinations
thereof.
8. The process according to claim 5 wherein said particulates have
an average particle diameter of between about 4 to about 10
microns.
9. The process according to claim 5 wherein said step of applying
pressure further includes applying a pressure of between about 150
to about 200 pounds per linear inch.
10. A process of providing a thermoplastic extrusion product
comprising the steps of: compounding a thermoplastic polymer
selected from the group consisting of polyvinyl chloride,
styrene-based polymers, olefins, and polyamides; introducing into
said thermoplastic resin in at least one of a compounding step or
an extruding step an effective amount of a particulate; extruding
said thermoplastic polymer; molding said thermoplastic polymer into
a desired shape; wherein said particulate additives increases wear
resistance and cut resistance of the thermoplastic article.
11. The process according to claim 10 wherein said step of applying
an effective amount of a particulate further comprises supplying
said particulate at a concentration of about 1 to about 25 grams
per square meter.
12. The process according to claim 10 wherein said particulate is
selected from the group consisting of silicates, silica oxide,
fumed silica, alumina, alumina oxides, ceramics, and combinations
thereof.
13. The process according to claim 10 wherein said particulates
have an average particle diameter of between about 4 to about 10
microns.
14. A thermoplastic article comprising: a molded thermoplastic
panel, said panel having an upper surface, a lower surface, and
four edges; a plurality of particulates selected from the group
consisting of silicas, silica oxides, fumed silicas, alumina,
alumina oxides, ceramics, and combinations thereof, said plurality
of particulates positioned within at least a portion of said panel
which includes at least one of said upper surface or said lower
surface; wherein, said plurality of particulates improves the wear
resistance of said at least one of said upper surface or said lower
surface.
15. The thermoplastic article according to claim 14 wherein said
plurality of particulates is concentrated along a surface region of
at least one of said upper surface or said lower surface.
16. The thermoplastic article according to claim 14 wherein an
upper surface of said panel is embossed, said embossed surface
further engaging said plurality of particulates.
17. The thermoplastic article according to claim 15 wherein said
plurality of particulates are present in a concentration of between
about 1 to about 25 grams per square meter of said surface
region.
18. The thermoplastic article according to claim 16 wherein said
embossed surface further defines a concentration of said hardened
particulates, said particles present in a concentration of between
about 1 to about 25 grams per square meter.
19. The thermoplastic article according to claim 14 wherein said
plurality of particulates is present in said thermoplastic panel in
a concentration of between about 1% to about 10% by weight.
Description
FIELD OF THE INVENTION
[0001] This invention is directed towards a process and the
resulting product of an extruded thermoplastic sheet or a molded
thermoplastic article having improved abrasion resistance and
scratch-resistant properties. The improved properties are achieved
by the addition of a plurality of particles of a hardened
substrate, such as aluminum oxide, which may be incorporated into
the thermoplastic material. The particulate additive imparts
greater wear resistance and scratch resistance to the thermoplastic
structure.
BACKGROUND OF THE INVENTION
[0002] Thermoplastic materials are widely used as a material for
articles of manufacture. For instance, it is known in the art to
use thermoplastic polyvinyl chloride (PVC) to mold articles of
furniture such as chair frames and other furniture articles. The
PVC resin is often provided with an integral wood grain finish to
simulate the appearance of real wood. While thermoplastic polymer
sheets and profiles offer high impact resistance, the wear
resistance and abrasion resistance is low.
[0003] It is also known to apply decorative films, papers, and
surface polymer layers to the laminated structure to improve the
appearance of the product. However, such overlayments are often
thin and hence prone to damage and are not easily repaired.
[0004] U.S. Pat. No. 6,106,654 provides a thermoset laminate in
which a paper web impregnated with melamine-formaldehyde resin is
applied as a surface layer to the laminate. The sheet is coated
with the impregnated paper, one side of the paper containing
aluminum oxide particles.
[0005] U.S. Pat. No. 5,763,048 discloses a PVC substrate having a
protective layer of a cured resin having polycarbonate particles
mixed with the resin. The resin is cured by applying ionizing
radiation to the PVC substrate.
[0006] U.S. Pat. No. 4,921,669 discloses scratch resistant coatings
suitable for use with a PVC substrate in which a separate coating
of a monomer mixture is applied to the PVC surface by
polymerization. The monomer has a high cross-linking density and
provides good scratch resistance.
[0007] While there are a variety of scratch resistant coatings and
resins known within the art, there remains room for improvement and
variation.
SUMMARY OF THE INVENTION
[0008] It is one aspect of one of the present embodiments to
provide for an extruded thermoplastic polymer which incorporates an
effective amount of a particulate additive such as aluminum oxide,
the particulate additive providing scratch resistance and wear
resistance to the extruded polymer.
[0009] It is yet another aspect of at least one of the present
embodiments to provide a process of incorporating an effective
amount of a hardened particulate which is incorporated directly
into the thermoplastic polymer during the compounding of the
polymer and prior to extrusion.
[0010] It is yet another aspect of at least one of the present
embodiments to provide a process of providing an extruded
thermoplastic polymer in which an effective amount of a particulate
additive is incorporated into a polymer extruding step.
[0011] It is yet an additional aspect of at least one of the
present embodiments to provide a molded thermoplastic polymer
containing between about 1% to about 10% by weight of an inorganic
filler selected from the group consisting of silicate, silica
oxide, fumed silicas, alumina, aluminum oxide, ceramics, and
combinations thereof, and having a particle diameter of about 4 to
about 10 microns.
[0012] It is another aspect of at least one of the present
embodiments to provide a thermoplastic sheet or extrusion molded
profile in which particulates are embedded into a surface of the
sheet by pressure application of the particulates into the softened
sheet surface.
[0013] It is yet another aspect of at least one of the present
embodiments to provide a process of providing a scratch resistant
coating to a thermoplastic extrusion product comprising the steps
of: providing a thermoplastic extruded product having a surface
temperature heated to a softening temperature; applying an
effective amount of a particulate, the particulate being applied at
a concentration of about 1 to about 25 grams per square meter;
mechanically pressing the particulate into the surface of the
extruded product using a pressure of about 150 to about 200 pounds
per linear inch; and allowing the thermoplastic material and
pressed particles to cool.
[0014] It is yet another aspect of at least one of the present
embodiments to provide a thermoplastic extruded sheet having a
scratch resistant surface comprising the steps of providing a
thermoplastic extruded sheet; embossing a surface of said
thermoplastic sheet, thereby imparting a matte finish to the sheet,
the matte finish comprising a series of surface elevations and
depressions; warming the matte surface to a softening temperature;
applying a plurality of particulates onto the matte surface; and
applying pressure to the matte surface and the particulates,
thereby embedding the particulates into the matte surface.
[0015] It is yet another aspect of at least one of the present
embodiments to provide a thermoplastic article comprising a molded
thermoplastic panel, the panel having an upper surface, a lower
surface, and four edges; a plurality of particulates selected from
the group consisting of silicas, silica oxides, fumed silicas,
alumina, alumina oxides, ceramics, and combinations thereof, the
plurality of particulates positioned within at least a portion of
the panel which includes at least one of the upper surface or the
lower surface; wherein, the plurality of particulates improves the
scratch resistance of at least one of the upper surface or the
lower surface.
[0016] The sheets, panels, and other articles made in accordance
with the present invention are useful in a variety of hard-wearing
surface applications. Such applications include, but are not
limited to, counter tops, flooring, and commercial or residential
furniture items.
[0017] These and other features, aspects, and advantages of the
present invention will become better understood with reference to
the following description and appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] A full and enabling disclosure of the present invention,
including the best mode thereof, to one of ordinary skill in the
art, is set forth more particularly in the remainder of the
specification, including reference to the accompanying
drawings.
[0019] FIG. 1 is a perspective view of one embodiment of
thermoplastic sheet made in accordance with the present
invention.
[0020] FIG. 2 is an alternative embodiment of a thermoplastic sheet
made in accordance with the present invention.
[0021] FIG. 3 is a third alternative embodiment setting forth a
thermoplastic sheet having an embossed surface made in accordance
with the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0022] Reference now will be made in detail to the embodiments of
the invention, one or more examples of which are set forth below.
Each example is provided by way of explanation of the invention,
not limitation of the invention. In fact, it will be apparent to
those skilled in the art that various modifications and variations
can be made in the present invention without departing from the
scope or spirit of the invention. For instance, features
illustrated or described as part of one embodiment, can be used on
another embodiment to yield a still further embodiment. Thus, it is
intended that the present invention cover such modifications and
variations as come within the scope of the appended claims and
their equivalents. Other objects, features, and aspects of the
present invention are disclosed in the following detailed
description. It is to be understood by one of ordinary skill in the
art that the present discussion is a description of exemplary
embodiments only and is not intended as limiting the broader
aspects of the present invention, which broader aspects are
embodied in the exemplary constructions.
[0023] In describing the various figures herein, the same reference
numbers may be used throughout to describe the same material,
apparatus or process pathway. To avoid redundancy, detailed
descriptions of much of the apparatus once described in relation to
a figure is not repeated in the descriptions of subsequent figures,
although such apparatus or process is labeled with the same
reference numbers.
[0024] As best seen in reference to FIG. 1, a first embodiment of
one of the present inventions is set forth. An extruded article,
seen here as a thermoplastic extruded PVC sheet 10 is provided.
Contained within the sheet are a plurality of particles 20 such as
aluminum oxide particles. The particles may be in a granular form,
preferably have high hardness values, and typically have a roughly
spherical shape. However, other shapes of particles as well as
variations in particle sizes may be used and which will offer
satisfactory results. Suitable hardened particles include
particulates of silica, silica oxides, fumed silicas, alumina,
aluminum oxides, various ceramic materials, and combinations
thereof which possess high strength and high abrasion resistant
properties.
[0025] The size and/or diameter of the particulates is not believed
critical with respect to the present invention. In accordance with
this invention, it has been found that a particle size of between
about 4 to about 10 microns (1000 to 1200 grit) for aluminum oxide
(Reade Advanced Materials) have been found to impart good scratch
resistance and wear properties to the thermoplastic extrusion
product 10 when present in a concentration of between about 1% to
about 10% by weight. As a general rule, increasing the amount of
hardened particles within the thermoplastic material increases the
cut and scratch resistance and abrasion resistance of the resulting
thermoplastic molded article. Alternatively, concentrating the
amount of particulates present along at least one surface region of
the molded article as described below, also brings about beneficial
improvements in the wear properties and scratch resistance of the
extruded sheet or molded article. Larger or smaller average sized
particulates may also be used.
[0026] In addition to PVC, other suitable thermoplastic resins may
be used to form extruded or molded thermoplastic articles. Such
thermoplastic materials include styrene-based polymers, olefins,
polyamides, and similar materials which are well known within the
art.
[0027] A thermoplastic article as set forth in FIG. 1 may be made
by incorporating the particulates directly into the thermoplastic
polymer. The particulates may be added during the compounding stage
prior to the polymer extrusion. Alternatively, a dosing screw or
other metering device may be used to introduce the hardened
particles directly to the extruder. Nonetheless, in either event,
the thermoplastic article contains a plurality of particulates
which are distributed throughout the polymer material.
[0028] As seen in reference to FIG. 2, an alternative embodiment of
a thermoplastic article may be seen in reference to a thermoplastic
sheet of PVC 110. A coating of particulates 120 is applied to the
surface of the molten sheet as the molten sheet exits the extruder
die. The particulates may be applied by a pneumatic sprayer, a
mechanical duster, or through an electrostatic disbursion. The
particulates are applied at a concentration of between about 1 to
about 25 grams per square meter. When so disbursed, the
particulates make contact with the surface of the molten sheet.
When applied prior to cooling of the molten sheet, the particulates
may be mechanically pressed into the upper molten polymer layer by
an application of pressure. Suitable pressure may be applied using
nip rollers or the use of a vacuum pressure against a platen. A
pressure roller, nip roller, or calendaring roll may be used to
apply a pressure of about 150 to about 200 pounds per linear inch
to sheet extrusion product. Vacuum pressure may be used in the case
of article profiles which are not suitable for passing through
pressure type rollers. Following the pressure application of the
particulates into the molten surface of the thermoplastic material,
the subsequently impregnated sheet or profile is then cooled as is
conventional within the art.
[0029] It is also possible to apply the particulates to the surface
of the thermoplastic material following the initial production of
the article. In such instances, the previously formed thermoplastic
sheet or profile is heated to a surface softening temperature and
the particulates are then applied to the surface of the article as
described above. Following application, the mechanical pressure is
applied as described above. If desired, the particulates may also
be heated to a temperature greater than the softening temperature
of the thermoplastic polymer prior to application. In so doing, the
particulates may more readily adhere to the surfaces to be
coated.
[0030] A third embodiment of the present invention is seen in
reference to FIG. 3. FIG. 3 sets forth a molded thermoplastic
article as seen in the form of an extruded sheet 210. A surface of
the extruded sheet is embossed using a conventional embossing
roller which creates a matte effect to the sheet. The embossing
roller places a series of raised surfaces 112 and depressions 114
along the sheet surface. Following embossing, the matte surface of
the sheet is raised to a softening temperature whereupon the
desired concentration of hardened particles 220 is applied and then
pressed into the surface of the sheet. As best seen in reference to
FIG. 3, the elevated ridges 212, along with the other surface
regions, become coated with a pressed layer of particulates. As a
result, the surface now defines a region containing a number of
particulates which impart excellent abrasion and scratch resistant
properties to the molded article. Further, the matte-like surface
of the alternating elevated regions and depressions serve to
minimize the appearance of scratches and other surface
imperfections which may occur.
[0031] In addition, as set forth in detail in Example 1 below, it
is also possible to coat or otherwise introduce the particulate
additive to the extruded sheet prior to a subsequent surface
embossing step.
[0032] The thermoplastic, surface hardened materials are
particularly well suited for use in constructing furniture from the
thermoplastic laminates. For instance, a thermoplastic PVC resin
may be provided in which a simulated wood grain appearance is
created by the use of pigments mixed in with the PVC resin. The PVC
pigmented resin provides an attractive wood grain appearance to the
resulting molded furniture article. By incorporating particulates
within the thermoplastic material and more particularly by placing
a surface layer of hardened particulates along the surfaces of the
thermoplastic molded article, the surface finish has improved
resistance to cuts and scratches. When used in materials such as a
pigmented thermoplastic article, the hardened particulates do not
alter or detract from the desired pigmentation of the extruded
product.
[0033] The thickness of the PVC or other thermoplastic polymer
products may be varied depending upon the capabilities of the
extrusion equipment and the desired end use. With respect to making
articles of furniture and thermoplastic panels which may be used in
the construction of furniture, a PVC thickness of about 2 mm is
sufficient. One way of making panels and various articles of
furniture using wood grained PVC can be found in relation to
Applicant's copending application having Ser. No. 09/656,281 filed
on Sep. 6, 2000, and which is incorporated herein by reference in
its entirety. In reference to the incorporated disclosure, the
extruded PVC article may be modified according to the present
invention to have an effective amount of the particulates. Such
particulates may be mixed uniformly throughout the extruded PVC
article or may be applied to one or more of the exterior surfaces
of the article. As discussed above, one or more surfaces of the PVC
article may be embossed which further minimizes the appearance of
scratches and allows a coating of the scratch-resistant
particulates to be applied to the embossed surface and to the
immediately adjacent region of the thermoplastic material.
[0034] It is also envisioned that the wear-resistant and
scratch-resistant thermoplastic polymer sheets described herein may
also be used as the wear surface of a flooring composite material.
The thermoplastic sheets may be molded and cut to desired shapes
and thicknesses and may be optionally secured to other substrates
so as to render a composite material suitable for use as a flooring
material, stair treads, or other similar articles designed for high
wear applications.
[0035] Articles made in accordance with the present invention were
evaluated according to test standards set forth in NEMA Standards
Publication LD 3-2000 and which are incorporated herein by
reference. In all instances, the inclusion of the particulates in
the thermoplastic article brings about an improvement in the
resistance to abrasions, cuts and scratches. Additional details of
construction may be found in reference to Example 1 below.
EXAMPLE 1
[0036] A high impact, thermoplastic wood-grain polyvinyl chloride
sheet was extruded from a 60-inch sheet die set at a 2.8 mm
thickness. As the extruded thermoplastic sheet exited the extruder,
a coating of aluminum oxide particulate was electrostatically
applied onto the top of the sheet at a concentration of 20
grams/meter.sup.2. The aluminum oxide had an average particle size
of between about 4 to about 10 microns.
[0037] The molten PVC sheet, coated with the aluminum oxide
particles, is passed through embossed calendaring rollers at a
pressure of about 150 pounds per linear inch. The gap between the
rollers was set at 2.4 mm in thickness. The resultant embossed
sheet was cooled and tested for abrasion resistance using
Wear-Resistant Test 3.13 and the Linear Glass Scratch-Resistance
Test 3.7 as set forth in the NEMA Publication LD 3-2000.
[0038] The wear-resistance procedure 3.13 uses sand paper placed on
abrader wheels to determine resistance to abrasive wear through.
Using the evaluation apparatus and materials set forth in the NEMA
3.13 publication, a wear-resistance of 3,200 cycles is obtained
which exceeds NEMA specifications for a high wear substrate.
[0039] Test method 3.7 was also used to determine linear glass
scratch resistance of the coated sheet surface. Test method 3.7
uses a scratch tool having a sharpness and hardness similar to
silica. The scratch resistance of the above described sheet was
determined to be 150 grams with the product sample having a
tristimulus Y value (lightness) of 30. These values represent a
high scratch resistant property for the evaluated thermoplastic
sheet.
[0040] Control samples of extruded PVC lacking the aluminum oxide
particulates fail to achieve the NEMA standards for high wear
resistance and exhibit poor scratch resistant values.
[0041] Although preferred embodiments of the invention have been
described using specific terms, devices, and methods, such
description is for illustrative purposes only. The words used are
words of description rather than of limitation. It is to be
understood that changes and variations may be made by those of
ordinary skill in the art without departing from the spirit or the
scope of the present invention, which is set forth in the following
claims. In addition, it should be understood that aspects of the
various embodiments may be interchanged, both in whole or in part.
Therefore, the spirit and scope of the appended claims should not
be limited to the description of the preferred versions contained
therein.
* * * * *