U.S. patent application number 12/039879 was filed with the patent office on 2008-07-31 for architectural fabric.
Invention is credited to William Greene, Thomas Kelmartin, Thomas Wallace, Robert Willmann.
Application Number | 20080178993 12/039879 |
Document ID | / |
Family ID | 37718211 |
Filed Date | 2008-07-31 |
United States Patent
Application |
20080178993 |
Kind Code |
A1 |
Kelmartin; Thomas ; et
al. |
July 31, 2008 |
Architectural Fabric
Abstract
An article useful as an architectural fabric consisting of (a) a
layer of fabric having a first surface and a second surface made of
polytetrafluoroethylene fibers; and (b) a fluoropolymer coating
disposed on at least the first surface of the fabric.
Inventors: |
Kelmartin; Thomas; (West
Chester, PA) ; Wallace; Thomas; (Rising Sun, MD)
; Greene; William; (Wilmington, DE) ; Willmann;
Robert; (Port Deposit, MD) |
Correspondence
Address: |
Allan M. Wheatcraft, Esquire;W. L. Gore & Associates, Inc.
551 Paper Mill Road
Newark
DE
19714-9206
US
|
Family ID: |
37718211 |
Appl. No.: |
12/039879 |
Filed: |
February 29, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11195911 |
Aug 2, 2005 |
|
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12039879 |
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Current U.S.
Class: |
156/243 ;
427/209 |
Current CPC
Class: |
Y10T 442/2639 20150401;
Y10T 442/2861 20150401; Y10T 442/2238 20150401; Y10T 442/259
20150401; Y10T 442/2631 20150401; Y10T 428/249921 20150401; D06N
3/0015 20130101; D06N 3/047 20130101; Y10T 442/2221 20150401; B32B
27/12 20130101 |
Class at
Publication: |
156/243 ;
427/209 |
International
Class: |
B29C 47/06 20060101
B29C047/06; B05D 1/00 20060101 B05D001/00 |
Claims
1. A method of making an architectural fabric comprising the steps
of (a) providing a fluoropolymer fabric having a first surface and
a second surface, and (b) extrusion coating the first surface of
said fluoropolymer fabric with THV by simultaneously extruding the
THV onto the fabric and nipping the fabric and extruded THV between
a first roll and a second roll.
2. A method of making an architectural fabric as defined in claim 1
further comprising the step of extrusion coating the second surface
of said fluoropolymer fabric with THV by simultaneously extruding
the THV onto the fabric and nipping the fabric and extruded THV
between a first roll and a second roll.
3. A method of making an architectural fabric for a retractable,
temporary, or permanent structure comprising the steps of: (a)
providing a layer of fabric having a first surface and a second
surface and comprising polytetrafluoroethylene fibers; (b) coating
THV onto said first surface of said fabric; and (c) coating THV
onto said second surface of said fabric.
Description
RELATED APPLICATION
[0001] The present application is a divisional application of
pending U.S. patent application Ser. No. 11/195,911 filed Aug. 2,
2005.
FIELD OF INVENTION
[0002] The present invention relates to fabric and, more
particularly, to architectural fabric that is waterproof, fire
retardant, flexible, durable, and aesthetically pleasing.
BACKGROUND OF INVENTION
[0003] Architectural fabric is fabric used as a building structure
or part of a building structure. It typically provides protection
for humans from elements such as wind, sun, and rain. It may be a
permanent structure or a temporary one. If temporary, it may be
retractable or removable, for example by folding, rolling, or
otherwise storing.
[0004] There are several requirements for architectural fabric. It
must be strong enough to withstand wind and other stresses during
assembly and use. It must be flexible and durable, so that it can
be folded or rolled and its strength and integrity are maintained
over time. It must be UV light resistant. UV light tends to degrade
and weaken fabric over time. A fabric that is UV resistant will
stand up under this exposure. It should generally be fire retardant
and waterproof. It should be easily seamed (or "welded"). It must
also be aesthetically pleasing.
[0005] A known architectural fabric is a composite consisting of
fiberglass fabric coated with PTFE. Although this product has
certain desirable qualities, it is not suitably flexible. The
fabric thus cannot be used efficiently in applications where
convenient removal of the fabric is needed.
[0006] Another known architectural fabric has a coating of PVC or
acrylic on polyester fabric. These products have flexibility but
only limited durability. Unless specially treated, these fabrics
are flammable and tend to degrade under UV light. After a certain
amount of flexing and UV exposure, these products develop cracks or
other imperfections that allow water to penetrate the fabric at the
point where it has been compromised.
[0007] Another known architectural fabric is that disclosed in U.S.
Pat. No. 6,770,577B2 to Kelmartin et al. The article disclosed
therein comprises a polytetrafluoroethylene fabric attached to at
least one composite membrane of a porous polytetrafluoroethylene
film having a fluoropolymer adhesive (such as THV) contained in its
pores. The porous polytetrafluoroethylene film is provided to make
the article durable and aesthetically pleasing. Addition of the
film requires additional processing, however. The film also tends
to mute any pigments or colors in the fabric or the THV.
[0008] An economical, weldable, waterproof, fire retardant
architectural fabric is needed in the industry.
SUMMARY OF INVENTION
[0009] The present invention provides an article consisting of (a)
a Layer of fabric having a first surface and a second surface made
of polytetrafluoroethylene fibers; and (b) a fluoropolymer coating
disposed on said first surface of said fabric. In another
embodiment, the invention further includes a fluoropolymer coating
disposed on the second surface of the fabric. The fluoropolymer
coating is preferably THV. The article of the present invention is
preferably waterproof, fire retardant, and has high seam strength.
It is also preferably an architectural fabric for retractable,
temporary, or permanent structures, such as tensile structures, and
is adapted to be joined to itself by welding.
[0010] In another aspect, the present invention provides a method
of making an architectural fabric for a retractable, temporary, or
permanent structure by: [0011] (a) providing a layer of fabric
having a first surface and a second surface and comprising
polytetrafluoroethylene fibers; [0012] (b) disposing THV on the
first surface of said fabric; and [0013] (c) optionally disposing
THV on the second surface of said fabric.
[0014] In another aspect, the invention provides a method of making
an architectural fabric comprising the steps of [0015] (a)
providing a fluoropolymer fabric [0016] (b) extrusion coating the
fluoropolymer fabric with THV by simultaneously extruding the THV
onto the fabric and nipping the fabric and extruded THV between a
first roll and a second roll.
BRIEF DESCRIPTION OF INVENTION
[0017] FIG. 1 is an optical micrograph of a cross-section of an
article in accordance with an exemplary embodiment of the present
invention.
[0018] FIG. 2 is a schematic illustration of an exemplary process
for making an article according to the present invention.
DETAILED DESCRIPTION OF INVENTION
[0019] The present invention will now be described with reference
to the figures in the drawing. FIG. 1 is an optical micrograph of a
cross-section of an article 10 according to an exemplary embodiment
of the present invention. In this exemplary embodiment, article 10
is an architectural fabric. Article 10 includes a fabric 11 made of
fibers 13 of a fluoropolymer material, preferably PTFE fibers that
have sufficient strength for a particular application, and most
preferably expanded PTFE fibers. Fabric 11 has a warp and a weft
direction, accounting for the cross-sectional views perpendicular
to and parallel to the axes of the individual fibers of fabric 11
shown in FIG. 1.
[0020] Fabric 11 has a first surface 20 and a second surface 21.
Disposed adjacent to first surface 20, which extends along fibers
13 in both the warp and weft direction, and extending in between
and among fibers 13 is a fluoropolymer coating 12, preferably a
terpolymer of tetrafluoroethylene, hexafluoropropylene, and
vinylidene fluoride (THV).
[0021] Article 10 is useful as an architectural fabric with only
first surface 20 covered by fluoropolymer coating 12. A preferable
embodiment, however, also has fluoropolymer coating 12 disposed on
second surface 21 (and extending between and among fibers 13 from
such second surface 21).
[0022] Fabric 11 is any material that is UV light resistant and
fire retardant. It must also be strong, flexible and durable. PTFE
fiber is preferred. Fabric made from expanded
polytetrafluoroethylene fibers is most preferred.
[0023] Fluoropolymer coating 12 is a material that is UV light
resistant and fire retardant. THV is preferred. This preferred
fluoropolymer coating is also advantageously flexible, adherent to
the fabric 11 (without being limited by theory, it is believed that
the THV is able to encapsulate the fibers of fabric 11 to form a
mechanical bond rather than a chemical bond) and clear or
translucent. Preferably, the coating on both sides of the fabric is
the same material. THV can be filled for functionality, such as
color, UV resistance (if needed, for example if no PTFE fabric is
used), and flame resistance.
[0024] Fluoropolymer coating 12 is preferably applied to fabric 11
by extrusion coating, although other methods, such as solvent
coating or lamination with or without the use of release layers are
alternatives. FIG. 2 depicts a preferred extrusion coating process
for making the architectural fabric of this invention. Fabric 11 is
passed between rolls 91 and 92 while fluoropolymer coating 12 is
simultaneously extruded onto fabric 11 from extruder 90. The
surfaces of rolls 91 and 92, as well as the temperature and speed
of the rolls are critical processing parameters for making the
present invention. Details of these parameters are given in the
example below.
[0025] Surprisingly, Applicant has discovered that the article of
the present invention functions well as an architectural fabric.
Contrary to the conventional wisdom expressed in U.S. Pat. No.
6,770,577B2 to Kelmartin et al., Applicant has discovered that an
architectural fabric made without the PTFE film disclosed in
Kelmartin is durable, processable and aesthetically pleasing. As
stated in this patent, "[w]hen THV alone is used to coat the
fabric, the surface has a blotchy appearance that is tacky. With
the inventive article, however, the surface appears uniform and is
not tacky. This also provides unexpected improvements in
processability. The article does not stick to or coat processing
rolls during manufacture." It was thus conventional wisdom before
the present invention that elimination of the porous
polytetrafluoroethylene film would be undesirable.
[0026] Also surprisingly, article 10 can be much more easily
seam-sealed to itself using welding techniques known in the art of
seam-sealing for example, with PTFE/fiberglass fabrics. This is a
result of the elimination of the microporous PTFE element described
in U.S. Pat. No. 6,770,577B2. A variety of seaming techniques can
be used. A secure seam is formed by applying heat (about 230
degrees C. for 45 seconds) and pressure to overlapped portions of
the inventive fabric. A suitable seam sealing device is an electric
impulse hot bar welder available from Aline Heat Sealing
Corporation, Cerritos Calif., part number HD-25. Surprisingly,
radio frequency welding can also be used, as can wedge welding and
hot-air welding. Using the invention, one can easily get a strong
weld without the need for special processing, or for adding
additional adhesives or seam tape as with other fabrics currently
used.
[0027] The following example is intended to illustrate, but not
limit, the present invention.
EXAMPLE
An architectural Fabric was Prepared as Follows
[0028] THV220 (Dyneon, Inc, Oakdale, Minn.) which was pigmented tan
was extruded using a single screw extruder and a slotted die at a
temperature of 250 C. It was directed vertically downward into a
nip created by two rolls; one being a TEFLON.RTM.-sleeved EPDM
rubber roll and the other a TEFLON.RTM.-coated steel roll. The
thickness of the extruded film was 175 micrometers. The EPDM roll
had a surface temperature of 90 C, and the steel roll had a surface
temperature of 115 C. The surface speed of the rolls was 2.75
meters per minute. Fabric woven of expanded PTFE fiber was obtained
from W.L. Gore & Associates, Inc. This fabric was woven in a
plain weave, 18 ends by 18 picks per centimeter. Each end and each
pick yarn was composed of two 500 denier expanded PTFE fibers plied
together.
[0029] The fabric entered the nip over the steel roll and was
pressed against the molten THV220 in the nip. The nip force was 130
Newtons per centimeter. The THV220 was pushed into the voids in the
fabric by the action of the nip. The resulting THV220/fabric
composite was wound onto a roll at the end of the extrusion
line.
[0030] The aforementioned THV220/fabric composite was then run a
second time on the extrusion line except that a second coating of
molten THV220 pigmented red was applied to the fabric face which
was not extruded upon in the first pass. The machine conditions
were the same for this second pass as they were for the first pass.
This material produced in this example was identified as 360-75.
The thickness of the THV220/fabric composite was 0.65 millimeters,
and the mass per unit area was 1240 grams per square meter.
TESTING
[0031] The fabric produced according to the above example was
tested for various properties as follows.
[0032] (1) Waterproofness
Apparatus:
[0033] RO/Distilled water
[0034] Thermometer
[0035] Low Hydrostatic Pressure Tester (Alfred Suter Co., Ramsey,
N.J., Model No. 502 Suter LHPT)
[0036] Timer
[0037] Water Circulator
Test Specimens:
[0038] Specimen size: circular sample of 41/2'' (11.4 cm)
diameter.
[0039] Specimens per sample: Three.
Conditioning: Condition the specimens at 21.+-.1.degree. C.
(70.+-.2.degree. F.), 65.+-.2% RH prior to testing.
Test Procedure:
[0040] 1. Check the water level in the tank. [0041] 2. Add water if
the level is too low. [0042] 3. Turn the pump on. [0043] 4. Check
that the water temperature is at 27.+-.3.degree. C.
(80.+-.5.degree. F.). [0044] 4.1 Run the motor to heat or add
heated water to the tank if the water temperature is too low.
[0045] 4.2 Float an ice pack, located in the freezer, in the tank
to lower the temperature if the water temperature is too high (or
becomes too high while testing), or add cold water. [0046] 5. Purge
the water lines. [0047] 6. Place a specimen face side down under
the specimen holder. [0048] 7. Clamp the specimen in place. [0049]
8. Open the valves to start water flow. [0050] 9. Set a timer for 3
minutes. [0051] 10. Start the timer when the gauge on the LPHT
tester reaches the specified pressure (1.1 psig). [0052] 11. Check
each specimen for leaks, Samples that leak are reported as
failures. Those that do not leak, pass. [0053] 11.1 Failures should
only be counted if leaks occur in the test area. [0054] 11.1.1
Drops of water penetrating the specimen at the clamped edge of the
specimen or within 0.32 cm (1/8'') of this edge shall not be
counted.
[0055] Three samples of the example material were tested as
described above. All three samples passed with no leakage.
[0056] (2) Fire Retardance
[0057] The example fabric was tested for fire retardance as
follows.
[0058] Apparatus:
TABLE-US-00001 Cabinet including Tirrill Burner Brass weights Metal
specimen holder and clips Scissors or hole punch Specimen mounting
block Butane lighter Timer (tenths of seconds) Disposable gloves
Metric ruler (1 mm graduations) Gas: methane 99% pure Plastic
bag
[0059] Test Specimens: [0060] Specimen size: 3''.times.12'' with
the 12'' length parallel to the test direction. Number of samples:
two. [0061] Conditioning: Condition the specimens at
70.+-.2.degree. F., 65.+-.2% RH prior to testing.
[0062] Test Procedure:
[0063] 1. Cut specimens as specified above. [0064] 1.1. Ensure that
the gas pressure is 2.5.+-.0.25 psi. [0065] 1.2. Turn power on
(control panel on counter). [0066] 1.3. Turn the pilot knob
slightly counter-clockwise, so that it is on. [0067] 1.4. Ignite
the pilot with the butane lighter. [0068] 1.5. Adjust the pilot
size to 1/8'' using the pilot knob. Measure the pilot flame from
its lowest point to the tip. [0069] 1.6. Set the flame ignition
timer to 120 seconds. [0070] 1.7. Turn the flame/fan knob to flame
and burn the flame for at least 2 minutes prior to the beginning of
each set up and testing session, [0071] 1.9. Adjust the flame
height to 1.5'' by turning the knob at the bottom of the burner
clockwise to increase the height or counter clockwise to decrease
the height. The tip of the flame should reach the top point of the
flame indicator. [0072] 1.10. Re-set the flame ignition timer to 12
seconds and re-light the flame. [0073] 1.11. Turn the flame/fan
knob to fan. [0074] 1.12. Place the metal specimen holder on the
mounting block. [0075] 1.13. Align a dummy specimen in the metal
holder with the short edge of the dummy aligned with the lower edge
of the holder. [0076] 1.14. Close the specimen holder and clamp
with the clips at two places on each side making sure the dummy is
smooth and flat in the holder. [0077] 1.15. Turn the flame/fan knob
to flame. [0078] 1.16. Light the flame with the butane lighter.
[0079] 1.17. Immediately turn the flame/fan knob to off. [0080]
1.18. Position the specimen holder securely in the cabinet. [0081]
1.19. Make sure the holder is positioned in the groove of the
holder rest at the back of the cabinet and the middle of the lower
edge of the specimen is centered 3/4'' above the burner. [0082]
1.20. Close the cabinet door and the hood sash. [0083] Note: The
specimen must be tested within 2 minutes of being placed in the
cabinet. [0084] 1.21. Turn the flame/fan knob to flame to start the
12-second flame. [0085] 1.22. Once the 12-second flame has
extinguished confirm that the pilot light is the proper size.
[0086] 1.23. Depress the door release button and allow the cabinet
to ventilate for 30 seconds or until all smoke and fumes are
removed. [0087] 1.24. Adjust the pilot light, if necessary, and
repeat steps 1.15 through 1.24 as needed until proper pilot size is
maintained.
[0088] 2. Testing: [0089] 2.1. Place the metal specimen holder on
the mounting block. [0090] 2.2. Align the specimen in the metal
holder such that the test area does not contain any identification
markings when the short edge of the specimen is aligned with the
lower edge of the holder. [0091] 2.3. Close the specimen holder and
clamp with clips at two places on each side making sure the
specimen is smooth and flat in the holder. [0092] 2.4. Turn the
flame/fan knob to flame. [0093] 2.5. Light the flame with the
butane lighter. [0094] 2.6. Immediately turn the flame/fan knob to
off. [0095] 2.7. Position the specimen holder securely in the
cabinet. [0096] 2.8. Make sure that the holder is positioned in the
groove of the holder rest at the back of the cabinet and that the
middle of the lower edge of the specimen is centered 3/4'' above
the burner. [0097] 2.9. Close the cabinet door and the hood, [0098]
Note: The specimens must be tested within 2 minutes of being place
in the cabinet. [0099] 2.10. Turn the flame/fan knob to flame to
start the 12-second flame. [0100] 2.11. Determine the after-flame,
and after-glow time, and the presence of melting or dripping, after
the 12-second flame extinguishes, and record in the lab database.
[0101] 2.11.1. After-flame: Using the timer mounted on the hood,
measure the number of seconds, to the nearest 0.1 seconds, that the
material continues to burn after the igniting flame extinguishes.
Do not turn the fan on until the specimen has stopped glowing,
regardless of whether or not the after-glow is being measured.
[0102] 2.11.2. After-glow: Using the automatic timer, measure the
number of seconds, to the nearest 0.1 seconds, that the material
glows after the flaming ends. The glow shall not be extinguished
even if after-glow time is not being evaluated because of the
glow's effect on char length. [0103] 2.11.3. Melt/Drip: Look for
signs of melting or dripping. [0104] The example material tested
for fire retardance had the following results, illustrating that
the material was indeed fire retardant.
Sample:360-75
TABLE-US-00002 [0105] Standard A B C Average Deviation Warp
Afterflame(sec) 1.3 1.2 1.2 1.23 0.05 Afterglow(sec) 0 0 0 0.00
0.00 Melt/Drip Melt/ Melt/ Melt/ No Drip No Drip No Drip Char 1.4
1.55 1.85 1.60 0.19 Length(cm) Fill Afterflame(sec) 1.2 1.1 1 1.10
0.08 Afterglow(sec) 0 0 0 0.00 0.00 Melt/Drip Melt/ Melt/ Melt/ No
Drip No Drip No Drip Char 1.6 1.45 1.85 1.63 0.16 Length(cm)
[0106] (3) Seam Strength
[0107] Two pieces of the example fabric were placed in overlapping
relationship in the warp direction, such that 2.5 inches (6.35 cm)
of each piece overlapped. No seam tape was used, nor was any
scuffing or abrasion performed on the areas to be welded. The
overlap was welded to form a seam with an Aline Welder Model HD-25
at 230 degrees C. for 45 seconds. Strips of the fabric were cut 2
inches (5.08 cm) wide by 14 inches (35.5 cm) long with the long
direction perpendicular to the seam. The seam strength was tested
by pulling the seam on a tensile tester (Instron Corporation,
Norwood Mass., Model 5567) with 4 inch (10.16 cm) gauge length at 2
inches (5.08 cm) per minute extension rate. Five such specimens
were produced. The results are tabulated below, and indicate a very
strong seam was produced using this simple welding technique on the
inventive fabric. A seam having a strength of at least 90% of the
nominal strength of the fabric is desired.
TABLE-US-00003 Percent of Nominal Fabric Strength Max Force Max
Force Max Force (456 Lb/in-4000 N/ Specimen (Lb/2 Inch) (Lb/Inch)
(N/5 cm) 5 cm) 1 929 465 4074 102% 2 901 451 3951 99% 3 868 434
3806 95% 4 884 442 3876 97% 5 882 441 3868 97% Average 893 446 3915
98% Std. Dev. 23.4 11.7 102.5 COV 2.6% 2.6% 2.6%
[0108] While particular embodiments of the present invention have
been illustrated and described herein, the present invention should
not be limited to such illustrations and descriptions. It should be
apparent that the changes and modifications may be incorporated and
embodied as part of the present invention within the scope of the
following claims.
* * * * *