U.S. patent application number 16/287760 was filed with the patent office on 2020-08-27 for roofing membrane with release liner having enhanced friction characteristics.
The applicant listed for this patent is JOHNS MANVILLE. Invention is credited to Daniel Blasini, Jordan Kortmeyer, Eric Alden Olson, Brenton Yancey.
Application Number | 20200270866 16/287760 |
Document ID | / |
Family ID | 1000003926569 |
Filed Date | 2020-08-27 |
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United States Patent
Application |
20200270866 |
Kind Code |
A1 |
Yancey; Brenton ; et
al. |
August 27, 2020 |
ROOFING MEMBRANE WITH RELEASE LINER HAVING ENHANCED FRICTION
CHARACTERISTICS
Abstract
A roofing membrane includes a waterproofing layer, and a release
liner removably attached to the waterproofing membrane. The release
liner has a coefficient of friction greater than the coefficient of
friction of the material of the waterproofing membrane. The release
liner is preferably left in place after initial installation of the
roofing membrane on a roof, and removed near the end of
construction, so that the waterproofing membrane is at least
partially protected from damage and dirt during later parts of the
construction.
Inventors: |
Yancey; Brenton; (Denver,
CO) ; Blasini; Daniel; (Lakewood, CO) ; Olson;
Eric Alden; (Thornton, CO) ; Kortmeyer; Jordan;
(Parker, CO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
JOHNS MANVILLE |
Denver |
CO |
US |
|
|
Family ID: |
1000003926569 |
Appl. No.: |
16/287760 |
Filed: |
February 27, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E04D 5/10 20130101; E04D
5/06 20130101; E04B 1/64 20130101; E04D 5/148 20130101 |
International
Class: |
E04D 5/10 20060101
E04D005/10; E04B 1/64 20060101 E04B001/64; E04D 5/14 20060101
E04D005/14; E04D 5/06 20060101 E04D005/06 |
Claims
1. A roofing membrane, comprising: a waterproofing layer having a
top major surface bounded by four edges; and a release liner
removably attached to and covering or substantially covering the
top major surface of the waterproofing layer, the release liner
having a coefficient of friction higher than the coefficient of
friction of the material of the waterproofing layer.
2. The roofing membrane of claim 1, wherein the kinetic coefficient
of friction of the release liner is at least 0.6.
3. The roofing membrane of claim 1, wherein the kinetic coefficient
of friction of the release liner is at least 0.7.
4. The roofing membrane of claim 1, wherein the kinetic coefficient
of friction of the release liner is at least 0.8.
5. The roofing membrane of claim 1, wherein the kinetic coefficient
of friction of the release liner is at least 0.9.
6. The membrane of claim 1, wherein the waterproofing layer
comprises one or more materials selected from the group consisting
of thermoplastic polyolefin (TPO), ethylene propylene diene monomer
(EPDM), polyvinyl chloride (PVC), and modified bitumen.
7. The membrane of claim 1, wherein the release liner includes a
chemical additive that raises the coefficient of friction of the
release liner as compared to a similar release liner lacking the
chemical additive.
8. The membrane of claim 7, wherein the chemical additive is a
styrene block copolymer.
9. The membrane of claim 1, wherein portions of the exposed surface
of the release liner are raised in relation to other portions.
10. The membrane of claim 9, wherein the raised portions are
embossed.
11. The membrane of claim 9, wherein the raised portions comprise
randomly oriented bumps.
12. The membrane of claim 9, wherein the raised portions form
intersecting lines.
13. The membrane of claim 1, wherein: the release liner includes a
chemical additive that raises the coefficient of friction of the
release liner as compared to a similar release liner lacking the
chemical additive; and portions of the exposed surface of the
release liner are raised in relation to other portions.
14. The membrane of claim 1, wherein the release liner covers the
top major surface of the waterproofing layer.
15. The membrane of claim 1, wherein the release liner
substantially covers the top major surface of the waterproofing
layer, leaving uncovered a strip of the top major surface of the
waterproofing layer at one edge of the top major surface.
16. The membrane of claim 1, wherein the release liner is removably
attached to the waterproofing layer without the use of an
adhesive.
17. The membrane of claim 16, wherein the release liner is attached
to the waterproofing layer using heat and pressure.
18. The membrane of claim 16, wherein the release liner includes a
tackifier.
19. The membrane of claim 1, wherein the release liner is removably
attached to the waterproofing layer using an adhesive.
20. The membrane of claim 1, wherein the release liner is removably
attached to the waterproofing layer using static cling.
21. A method of applying a roofing membrane on a roof, the method
comprising: laying a first row of roofing membrane on the roof, the
first row of roofing membrane including a first waterproofing layer
and a first release liner on top of a top major surface of the
first waterproofing layer, the first release liner having a
coefficient of friction higher than that of the material of the
first waterproofing layer; and laying a second row of roofing
membrane on the roof, the second row of roofing membrane having a
second waterproofing layer and a second release liner, the second
release liner having a coefficient of friction higher than that of
the material of the second waterproofing layer, the second row of
roofing membrane overlapping the first row such that a bottom major
surface of the second waterproofing layer contacts an uncovered
strip at one edge of the top major surface of the first
waterproofing layer; and bonding the first and second rows of
roofing membrane together in their area of overlap.
22. The method of claim 21, further comprising uncovering the strip
of the top major surface of the first waterproofing layer by
peeling back a portion of the first release liner.
23. The method of claim 22, further comprising removing the portion
of the first release liner by tearing the first release liner along
a perforation.
24. The method of claim 21, wherein the release liner of the first
row of roofing membrane substantially covers the top major surface
of the first waterproofing layer, leaving uncovered the strip of
the top major surface of the first waterproofing layer.
25. The method of claim 21, further comprising removing the first
and second release liners.
26. A method of making a roofing membrane, the method comprising:
providing a polymeric waterproofing layer having a top major
surface; and removably attaching a release liner to the top major
surface of the waterproofing layer, the release liner having a
coefficient of friction higher than that of the material of the
waterproofing layer.
27. The method of claim 26, wherein removably attaching the release
liner to the waterproofing layer comprises placing an adhesive
between the waterproofing layer and the release liner.
28. The method of claim 26, further comprising embossing the
release liner.
Description
BACKGROUND
[0001] Low slope or flat roofs are typically covered with
waterproofing materials. In a "built up roof" (BUR), multiple
components such as liquid asphalt and ballast are separately
applied to the roof, often over an insulation layer. An alternative
to the built up roof is to use a "singly-ply" membrane. A single
ply membrane may be a large, flat, flexible membrane supplied on a
roll, and rolled out on top of the roof, typically on top of the
insulation layer. The term "single-ply" is used to describe a roof
having a single application of a membrane, but the membrane itself
may comprise multiple layers such as polymer layers, reinforcing
layers, adhesive layers, coatings, and the like. Typical base
materials used for single ply membranes are thermoplastic
polyolefin (TPO), ethylene propylene diene monomer (EPDM),
polyvinyl chloride (PVC), and modified bitumen.
[0002] A single ply membrane may be supplied in any workable size,
for example in rolls up to 50 feet wide or more containing 100
linear feet or more of membrane. When a roof is too large to be
covered by a single piece of membrane, multiple pieces may be
overlapped and joined at the seams using a waterproof joining
method such as heat welding or adhesive bonding. More detail about
the use of single ply membranes may be found in U.S. Patent
Application Publication No. 2016/0362894, published Dec. 15, 2016
and titled "Sheet Roofing with Pre-Taped Seams and Tape Therefor",
the entire disclosure of which is hereby incorporated by reference
herein for all purposes.
[0003] FIG. 1 illustrates a typical flat roof installation.
Building 100 has a flat roof 101, covered by rows of a single ply
membrane 102. The rows of single ply membrane 102 have been joined
at their adjacent seams 103, so that roof 101 has been covered with
a continuous waterproof barrier, other than at necessary
penetrations of the roof. For example, as is typical, a number of
pieces of electrical and mechanical equipment may be placed on roof
101, and may require connections to through the roof to other
equipment inside building 100. In FIG. 1, air conditioning
equipment 104, a cellular telephone site 105, and a plumbing drain
vent 106 are illustrated, but on other roofs, other kinds of
equipment may be present. On a large roof, dozens of pieces of
equipment may be present, or more.
[0004] Roofing membrane 102 may preferably be white in color, to
reflect sunlight and reduce the energy required to cool building
100. While roofing membrane 102 may be installed in a clean and
undamaged condition, access to equipment on the roof may require
that workers walk on roofing membrane 102, for example to seal
roofing membrane 102 around the penetrations, or to install and
connect the equipment at a later stage in the construction of
building 100.
[0005] It is desirable that workers be provided access to the roof
as needed, safely, and without damaging or discoloring roofing
membrane 102.
BRIEF SUMMARY
[0006] According to one aspect, a roofing membrane comprises a
waterproofing layer having a top major surface bounded by four
edges and a release liner removably attached to and covering or
substantially covering the top major surface of the waterproofing
layer. The release liner has a coefficient of friction higher than
the coefficient of friction of the material of the waterproofing
layer.
[0007] According to another aspect, a method of applying a roofing
membrane on a roof comprises laying a first row of roofing membrane
on the roof, the first row of roofing membrane including a first
waterproofing layer and a first release liner on top of a top major
surface of the first waterproofing layer. The first release liner
has a coefficient of friction higher than that of the material of
the first waterproofing layer. The method further comprises laying
a second row of roofing membrane on the roof, the second row of
roofing membrane having a second waterproofing layer and a second
release liner. The second release liner has a coefficient of
friction higher than that of the material of the second
waterproofing layer. The second row of roofing membrane overlaps
the first row such that a bottom major surface of the second
waterproofing layer contacts an uncovered strip at one edge of the
top major surface of the first waterproofing layer. The method
further comprises bonding the first and second rows of roofing
membrane together in their area of overlap.
[0008] According to another aspect, a method of making a roofing
membrane comprises providing a polymeric waterproofing layer having
a top major surface, and removably attaching a release liner to the
top major surface of the waterproofing layer.
[0009] The release liner has a coefficient of friction higher than
that of the material of the waterproofing layer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 shows a typical flat roof installation on a
building.
[0011] FIG. 2 shows a cross-section view of a roofing membrane in
accordance with embodiments of the invention.
[0012] FIG. 3 shows a perspective view of the roofing membrane of
FIG. 2, with a release liner partially pulled back from a
waterproofing layer, in accordance with embodiments of the
invention.
[0013] FIG. 4 shows a release liner according to other embodiments
of the invention.
[0014] FIG. 5 illustrates a roofing membrane in accordance with
other embodiments of the invention.
[0015] FIG. 6 illustrates a method of installing a roofing
membrane, in accordance with embodiments of the invention.
[0016] FIG. 7 illustrates a roofing membrane in accordance with
other embodiments or the invention.
[0017] FIG. 8 illustrates a method of installing a roofing
membrane, in accordance with other embodiments of the
invention.
[0018] FIG. 9 illustrates a roofing membrane having a release liner
that has an embossed surface, in accordance with embodiments of the
invention.
[0019] FIG. 10 illustrates one example technique for producing a
roofing membrane in accordance with embodiments of the
invention.
[0020] FIG. 11 illustrates an embossing pattern in accordance with
embodiments of the invention.
[0021] FIG. 12 illustrates an embossing pattern in accordance with
other embodiments of the invention.
[0022] FIG. 13 illustrates an embossing pattern in accordance with
other embodiments of the invention.
[0023] FIG. 14 illustrates an embossing pattern in accordance with
other embodiments of the invention.
[0024] FIG. 15 illustrates an embossing pattern in accordance with
other embodiments of the invention.
[0025] FIG. 16 illustrates an embossing pattern in accordance with
other embodiments of the invention.
[0026] FIG. 17 illustrates an embossing pattern in accordance with
other embodiments of the invention.
DETAILED DESCRIPTION
[0027] FIG. 2 shows a cross-section view of a roofing membrane 201
in accordance with embodiments of the invention. Roofing membrane
201 is a single ply membrane having two layers--a waterproofing
layer 202 and a release liner 203.
[0028] Waterproofing layer 202 may be made of any suitable
material, and in different embodiments may comprise thermoplastic
polyolefin (TPO), ethylene propylene diene monomer (EPDM),
polyvinyl chloride (PVC), modified bitumen, or a combination of
materials. Waterproofing layer 202 may have any suitable thickness,
for example between 0.020 and 0.250 inches, preferably between
0.040 and 0.125 inches. Roofing membrane 201 may be supplied in
rolls of any workable size, for example rolls up to 50 feet wide or
more containing 100 linear feet or more of membrane, such that
membrane 201 is supplied in rectangular sheets up to 50.times.100
feet or more. The top face of the membrane may be termed the top
major surface, and is bounded by four edges forming the rectangular
perimeter of the sheet. Similarly, waterproofing layer 202 has a
bottom major surface opposite the top major surface and intended to
be placed against a roof.
[0029] While waterproofing layer 202 is shown monolithically, it
may include other materials and layers. For example, waterproofing
layer 202 may include an embedded reinforcing mesh made of
fiberglass or other materials. In another example, waterproofing
layer 202 may include an adhesive on its bottom major surface such
that roofing membrane 201 is self-adhesive. In this case, another
release liner (not shown) may be provided below the adhesive
layer.
[0030] Smaller rolls may be provided if desired. In addition,
compatible patching sheets, cap sheets, tapes, and other items may
be made available for convenient installation of membrane 201 on
roofs of various shapes and sizes.
[0031] The top major surface of waterproofing layer 202 is
preferably light in color, for example white.
[0032] Release liner 203 is preferably a thin layer removably
attached to the top major surface of waterproofing layer 202, and
covering or substantially covering the top major surface. Release
liner 203 is intended to be removed as a last or nearly-last step
in the installation of roofing membrane 201 on a roof. Roofing
membrane 201 may be installed with release liner 203 in place, and
workers permitted to walk on the roof (on top of release liner 203)
to complete later tasks in the construction or re-roofing of the
building. For example, workers may seal joints between strips of
roofing membrane 201, may seal around any penetrations of the roof,
may install and connect electrical or mechanical equipment on the
roof, or may perform other tasks.
[0033] Once such tasks are completed, it may be expected that foot
traffic on the roof will be negligible. Near the end of the
project, release liner 203 is removed, exposing the top major
surface of waterproofing layer 202, in pristine or near-pristine
condition. Release liner 203 substantially protects waterproofing
layer 202 from dirt, scuffs, wear, or other events that might
otherwise be detrimental to the integrity and reflectivity of
waterproofing layer 202, and obviates the need for expensive and
time-consuming cleaning of the newly-installed roof. After removal,
release liner 203 may be discarded or preferably recycled.
[0034] Release liner 203 may conveniently be made of one or more
layers of one or more polyolefins such as polypropylene or
polyethylene, but in other embodiments may be made of any suitable
material or combination of materials. Release liner 203 may be made
of recycled materials, and may be recyclable once removed.
[0035] In particular, release liner 203 has a coefficient of
friction greater than that of the material of waterproofing layer
202 itself. For example, a TPO membrane may have a kinetic
coefficient of friction of about 0.575, and release liner 203 may
have a kinetic coefficient of friction greater than 0.575, and thus
may be considered to have enhanced friction characteristics, as
compared with the material of waterproofing layer 202. In other
embodiments, release liner 203 may have a kinetic coefficient of
friction of at least 0.6, at least 0.7, at least 0.8, at least 0.9,
at least 0.95, or another value. In one embodiment, release liner
203 has a kinetic coefficient of friction of about 0.965.
[0036] For the purposes of this disclosure, recited coefficients of
friction are kinetic coefficients unless otherwise stated. The
kinetic coefficient of friction is also sometimes known as the
dynamic coefficient of friction, and is a unitless ratio computed
by dividing the force required to drag one object over another by
the normal force between the objects, once motion has begun. As is
well known, the kinetic coefficient of friction of a material is
generally lower than the static coefficient of friction. The static
coefficient of friction is the unitless ratio computed by dividing
the force required to start dragging motion between two objects by
the normal force between them.
[0037] Also for the purposes of this disclosure, kinetic
coefficients of friction were measured using a modified version of
the ASTM 1894--"Standard Test Method for Static and Kinetic
Coefficients of Friction of Plastic Film and Sheeting" method. In
the standard ASTM 1894 test, a weighted sled is pulled across a
second stationary, flat surface at a speed of 150 mm/min, and the
contacting surfaces of the weighted sled and the flat surface are
made of the same material under test. In the modified procedure
used in this disclosure, the sled is covered in rubber and the flat
surface is the release liner being tested. This is in order to find
the coefficient of friction between the rubber (such as a sole of a
shoe) and the liner. The test fixture used to measure the
coefficient of friction was a Custom Scientific Instruments, Inc.
CS-1525-007.
[0038] Release liner 203 may be removably attached to waterproofing
layer 202 in any suitable way. In some embodiments, release liner
203 may be attached to waterproofing layer 202 using an adhesive
such as a hot-melt adhesive, a pressure sensitive adhesive, a
urethane based adhesive, an polyisoprene based adhesive, or another
kind of adhesive. In some embodiments, any adhesive may be applied
across the entire release liner. In other embodiments, the adhesive
may be applied in bands, patches, or another pattern in which less
than the entire surface of the release liner is covered, in order
to reduce the amount of adhesive required or to reduce the force
needed to separate the release liner from the waterproofing
layer.
[0039] For example, FIG. 3 shows a perspective view of roofing
membrane 201 with release liner 203 partially pulled back from
waterproofing layer 202, in accordance with embodiments of the
invention. The underside 301 of release liner 203 is uniformly
coated with adhesive. FIG. 4 shows another embodiment, in which
underside 301 of release liner 203 is coated with patches 401 of
adhesive, such that less than the entire underside 301 is coated.
Any other suitable partial coating technique may be used, including
random splattering of the adhesive.
[0040] Any adhesive used may be environmentally friendly. For
example, the adhesive may be biodegradable, or water soluble, or
may have other properties for low environmental impact.
[0041] In other embodiments, water proofing layer 202 and release
liner 203 may be removably attached without the use of any
adhesive. For example, either or both of release liner 203 and
waterproofing layer 202 may be statically charged, so that they are
attached by electrostatic attraction. In some embodiments,
waterproofing layer 202 and release liner 203 may simply subjected
to heat and pressure during the manufacturing of roofing membrane
201, forming a temporary light attachment between the two.
[0042] In some embodiments, release liner 203 may include a
tackifier in its formulation, so that it tends to cling to
waterproofing layer 202 without being fully adhered. Various
additives for imparting tack to the formulation of release liner
203 are available. For example, the Vistamaxx.RTM. line of polymers
available from ExxonMobil includes polymers with good tack
properties.
[0043] FIG. 5 illustrates a roofing membrane 501 in accordance with
other embodiments. In this example embodiment, release liner 203 is
split, so that it may be removed from waterproofing layer 202 in
two pieces. This may allow for more convenient handling of release
liner 203 during removal. Preferably, the edges of the two pieces
of release liner 203 meet at a zero-width or near-zero-width slit
502, so that the upper major surface of waterproofing layer 202
remains protected.
[0044] FIG. 6 illustrates a method of installing a roofing
membrane, in accordance with embodiments of the invention. A
roofing membrane such as roofing membrane 201 is shown in this
example. Roofing membrane 201a has been previously laid on a roof,
and its release liner 203 lifted and folded back to form a flap 601
along one edge 602 of roofing membrane 201a. A second piece of
roofing membrane, 201b, is unrolled and placed such that the bottom
major surface of roofing membrane 201b overlaps and lies on top of
the exposed portion of the top major surface of roofing membrane
201a, as shown at 603. The two roofing membranes may be joined and
sealed by any suitable technique, for example by heat welding, by
an adhesive pre-applied to either or both of roofing membranes 201a
and 201b, or by an adhesive applied on the rooftop during
installation. The overlapping area of the two roofing membranes is
preferably wide enough to ensure a good seal between the membranes
201a and 201b. In some embodiments, the overlapping area may be
about 2 to 6 inches wide, for example about 4 inches wide.
[0045] The flap 601 of release liner 203 folded back from roofing
membrane 201a may conveniently be laid back down on top of the
overlapping portion of roofing membrane 201b. In other embodiments,
the flap may be cut off, or left loose. In some embodiments,
release liner 203 may be perforated to allow for easy removal of
flap 601.
[0046] FIG. 7 illustrates a roofing membrane 701 in accordance with
other embodiments or the invention. Roofing membrane 701 is similar
to roofing membrane 201 in that it includes a waterproofing layer
702 and a release liner 703. However, while release liner 703
substantially covers the top major surface of waterproofing layer
702, it does not completely cover the top major surface of
waterproofing layer 702. Rather, a strip 704 of the top major
surface of waterproofing layer 702 is left uncovered by release
liner 703, along one edge 705 of waterproofing layer 702.
[0047] This arrangement facilitates installation of roofing
membrane 701, as shown in FIG. 8. A second row of roofing membrane
701b can be overlapped and sealed to a previously-laid first row
701a without the need to remove or fold back any release liner from
strip 704 along edge 705 of the first row 701a of release liner.
The overlapped area shown at 803 can be sealed in any suitable
manner, as discussed above.
[0048] The coefficient of friction of release liner 203 may be
enhanced, for example using a chemical additive in the material of
release liner 203. In some embodiments, release liner 203 may
comprise a styrene block copolymer such as Kraton.RTM. styrene
block copolymer available from Kraton Corporation of Houston, Tex.,
USA, or a Vistamaxx.RTM. polymer available from ExxonMobil Chemical
Company of Spring, Tex., USA.
[0049] Methods of producing a plastic film having an enhanced
coefficient of friction are given in U.S. Patent Application
Publication No. 2018/0117874 of Rothbauer et al., published May 3,
2018 and titled "Reusable, Non-Adhesive Protective Cover", the
entire disclosure of which is hereby incorporated by reference
herein for all purposes.
[0050] As is discussed above, the coefficient of friction of a
release liner embodying the invention may be enhanced by the use of
an additive in the material of the release liner. In addition or
alternatively, the release liner may be textured or otherwise
formed, for example with raised bumps, to provide a mechanical
enhancement to its friction characteristics. In one example, FIG. 9
illustrates a roofing membrane 901 having a release liner 902 that
has an embossed surface, in accordance with embodiments of the
invention. In this example, release liner 902 has a number of
elongated bumps 903 arranged at crossing angles, creating a pattern
similar to that often used on steel stair treads for enhancing
traction. In other embodiments, bumps 903 may be of any suitable
shape, for example round, polygonal, irregular, or another shape,
and may be placed in any suitable arrangement, for example in a
pattern or randomly.
[0051] In other embodiments, the pattern on the protective film may
be formed by one or more of horizontal lines, vertical lines,
diagonal lines, squares, or diamond patterns. Also usable are
patterns generated from embossing shapes such as random rough
texture, squares, inverted squares, dotlines and reversed dotlines.
In other embodiments, recesses may be formed into release liner
902, rather than raised bumps.
[0052] The sizes of the raised features may range from 0.1 mm to 25
mm, and the features may be arranged in a repeating pattern that
repeats every 0.1 to 25 mm or more across the release liner. He
height of any raised features (or depth of any recessed features)
may preferably be between 0.001 mm to 0.1 mm, although other
heights may be used. The heights of bumps 903 may be exaggerated in
FIG. 9.
[0053] In one preferred embodiment, the embossed pattern is made up
of repeating adjacent diamond-shapes about 1.2 mm across and a
height of about 0.20 mm.
[0054] Methods of producing a plastic film having an embossed
surface are given in U.S. Patent Application Publication No,
2018/0117874 of Rothbauer et al., previously incorporated by
reference.
[0055] FIG. 10 illustrates one example technique for producing a
roofing membrane in accordance with embodiments of the invention.
In this example, both the waterproofing layer 202 and the release
liner 203 have been previously fabricated and stored on rolls. A
first roll 1001 of waterproofing layer 202 and a second roll 1002
of release liner 203 are mounted on shafts. Release liner 203 may
optionally be fed between an embossing roller 1003 (the roughness
of which is exaggerated in FIG. 10) and a rubber roller 1004, to
raise bumps on release liner 203, transforming release liner 203
into an embossed release liner such as release liner 902 discussed
above. Waterproofing layer 202 is also fed off of roll 1001, and
waterproofing layer 202 and release liner 902 are brought together
at compression rollers 1005, where release liner 902 is removably
attached to waterproofing layer 202. Optionally, an adhesive may be
placed between waterproofing layer 202 and release liner 902, for
example by an extruder or other dispenser 1006. The completed
roofing membrane is then wound onto a roll 1007 for packaging and
shipment.
[0056] Within this basic framework, many variations are possible.
For example, embossing roller 1003 may be omitted, so that the
resulting roofing membrane is similar to un-embossed roofing
membrane 201. In other embodiments, either or both of waterproofing
layer 202 and release liner 203 may be fabricated, for example by
extrusion, immediately before being brought together to form a
complete roofing membrane. In other embodiments, waterproofing
layer 202 and release liner 203 may be coextruded onto a single
roller. Any workable combination of steps and processes may be
used.
EXAMPLES
[0057] A number of example release liners were produced and
characterized, as summarized in Table 1 below. Also included in
Table 1 is a comparative reading taken from a TPO membrane having
no release liner. In all of the examples of Table 1, no chemical
additives or treatments were included in the release liner for the
specific purpose of enhancing the friction characteristics of the
release liner. The heights of the embossed features were between 20
and 250 micrometer (0.02 and 0.25 mm).
TABLE-US-00001 TABLE 1 Friction Effect of Example Release Liners
Liner Emboss Static Kinetic % .DELTA. % .DELTA. Liner Material
Pattern COF COF Static COF Kinetic COF Comparative TPO N/A N/A
0.688 0.575 N/A N/A Membrane - no liner 1 Nylon Taffeta 0.755 0.803
9.74% 39.69% 2 Polypropylene Diamond 0.984 0.965 42.95% 67.97% 3
Rubber Matte/Smooth 0.667 0.604 -3.12% 5.13% 4 Polypropylene Linen
0.524 0.470 -23.91% -18.28% 5 Polypropylene Orange Peel 0.482 0.390
-30.01% -32.11% 6 Polypropylene Suede 0.622 0.593 -9.67% 3.13% 7
Polyprpylene Stipple 0.699 0.665 1.60% 15.67% 8 Polypropylene Matte
0.800 0.802 16.28% 39.60% 9 Polypropylene Taffeta 0.692 0.587 0.58%
2.18% 10 Polypropylene Matte 0.793 0.784 15.26% 36.47%
[0058] The various embossing patterns are illustrated in FIGS.
11-17.
[0059] FIG. 11 illustrates an embossing pattern having intersecting
embossed lines forming rectangles. In the example of FIG. 11, the
rectangles are squares about 0.5 mm on a side, and are oriented at
a 45-degree angle to the edges of the release liner. In other
embodiments, the rectangles may be at any other orientation angle,
including aligned with the edges of the release liner. Rectangles
of other sizes may be used. The pattern of FIG. 11 is denoted as a
"taffeta" pattern, but this name is for convenient reference only,
and is not to be taken as limiting in any way.
[0060] FIG. 12 illustrates an embossing pattern having intersecting
embossed lines forming diamond shapes. In the example of FIG. 12,
the diamond shapes are about 2.0 by 4.0 mm, with their long axis
aligned with an edge of the release liner. In other embodiments,
the diamond shapes may be at any other orientation angle, and may
be of other sizes. The pattern of FIG. 12 is denoted as a "diamond"
pattern, but this name is for convenient reference only, and is not
to be taken as limiting.
[0061] FIG. 13 illustrates an embossing having small, randomly
oriented embossed bumps. In the example of FIG. 13, the bumps are
between about 0.1 and 0.3 mm in size. The pattern of FIG. 13 is
denoted as a "matte" pattern, but this name is for convenient
reference only, and is not to be taken as limiting.
[0062] FIG. 14 illustrates an embossing pattern having intersecting
embossed lines forming rectangular shapes. Some of the lines are
wider than others, and form a pattern of larger rectangles having
dimensions of about 0.5 to 3.0 mm on each side. Within the larger
rectangles, narrower lines form approximately square features about
0.3 mm on a side. The rectangular features are aligned with an edge
of the release liner in FIG. 14, but other sizes or orientations
may be used. The pattern of FIG. 14 is denoted as a "linen"
pattern, but this name is for convenient reference only, and is not
to be taken as limiting.
[0063] FIG. 15 illustrates another embossing pattern having small,
randomly oriented embossed bumps. The example of FIG. 15 may be
similar to the example of FIG. 13, except that the bumps are
somewhat larger. The pattern of FIG. 15 is denoted as a "matte"
pattern, but this name is for convenient reference only, and is not
to be taken as limiting.
[0064] FIG. 16 illustrates another embossing pattern having small,
randomly oriented embossed bumps. The example of FIG. 16 may be
similar to the examples of FIGS. 13 and 15, except that the bumps
are still larger, and are elongated so that they intertwine with
each other to a degree. The pattern of FIG. 16 is denoted as a
"suede" pattern, but this name is for convenient reference only,
and is not to be taken as limiting.
[0065] FIG. 17 illustrates another embossing pattern having
randomly oriented embossed bumps. The example of FIG. 17 may be
similar to other examples, except that the bumps are still larger.
In FIG. 17, the bumps are between about 0.5 and 1.0 mm across, but
other sizes may be used. The pattern of FIG. 17 is denoted as a
"stipple" pattern, but this name is for convenient reference only,
and is not to be taken as limiting.
[0066] As is apparent from Table 1, the embossing pattern has an
effect on the coefficient of friction of the release liner. A
diamond pattern, for example as illustrated in FIG. 12, may achieve
a coefficient of friction of up to 0.965 or more in a polypropylene
release liner--an improvement of nearly 68 percent over the
comparative TPO membrane having no release liner. Other embossing
patterns showing the most significant friction enhancements include
the "taffeta" pattern, for example as illustrated in FIG. 11, and
the "matte" pattern illustrated in FIG. 13.
[0067] The invention has now been described in detail for the
purposes of clarity and understanding. However, those skilled in
the art will appreciate that certain changes and modifications may
be practiced within the scope of the appended claims.
* * * * *