U.S. patent application number 11/199943 was filed with the patent office on 2007-03-01 for skid resistant surfaces.
Invention is credited to Felek Jachimowicz, Paul J. Westgate, Robert A. Wiercinski, David P. Zalanowski.
Application Number | 20070044397 11/199943 |
Document ID | / |
Family ID | 37546570 |
Filed Date | 2007-03-01 |
United States Patent
Application |
20070044397 |
Kind Code |
A1 |
Wiercinski; Robert A. ; et
al. |
March 1, 2007 |
Skid resistant surfaces
Abstract
Skid-resistant surfaces as described having either a
pressure-sensitive adhesive layer or a highly filled, textured
binder to reduce skidding. The surfaces are applied to trafficable
surfaces such as roof and floors. Products such as roof
underlyments bearing the surfaces are described in particular.
Inventors: |
Wiercinski; Robert A.;
(Lincoln, MA) ; Zalanowski; David P.; (Brighton,
MA) ; Westgate; Paul J.; (Littleton, MA) ;
Jachimowicz; Felek; (Brookline, MA) |
Correspondence
Address: |
W. R. GRACE & CO.-CONN;ATTENTION: PATENT DEPARTMENT
62 WHITTMORE AVENUE
CAMBRIDGE
MA
02140
US
|
Family ID: |
37546570 |
Appl. No.: |
11/199943 |
Filed: |
August 9, 2005 |
Current U.S.
Class: |
52/177 |
Current CPC
Class: |
E04D 5/10 20130101; E04D
12/002 20130101 |
Class at
Publication: |
052/177 |
International
Class: |
E04F 15/00 20060101
E04F015/00 |
Claims
1. A pedestrian trafficable surface that is skid-resistant when wet
and which comprises a roofing substrate or a flooring substrate
having a non-skid coating comprising a pressure sensitive adhesive
or a filled textured binder.
2. The surface of claim 1 wherein the filler in said binder is
substantially coated with binder.
3. The surface of claim 1 wherein filled binder protrudes from the
surface.
4. A roofing underlayment comprising at least one support layer
having first and second opposite major surfaces, and a pressure
sensitive layer attached to said first major surface of said at
least one support layer, such that upon application of said
underlayment to a roof, said pressure sensitive layer provides a
skid resistant surface for foot traffic thereon.
5. The roofing underlayment of claim 4, wherein said at least one
support layer is a woven or non-woven fabric.
6. The roofing underlayment of claim 4, wherein said at least one
support layer is a polyolefin film.
7. The roofing underlayment of claim 4, wherein said at least one
support layer comprises spun bonded polypropylene or woven
polypropylene.
8. The roofing underlayment of claim 4, wherein said pressure
sensitive layer comprises a rubber selected from the group
consisting of styrene-isoprene-styrene block copolymers,
styrene-butadiene-styrene block copolymers,
styrene-ethylene-butylene-styrene block copolymers strene/butadiene
rubber, natural rubber, silicone rubber, butyl rubber,
polyisoprene, polyisobutylene, chloroprene, ethylene-propylene
rubber, ethylene alpha olefin, polybutadiene, nitrile rubbers, and
acrylic rubber.
9. The roofing underlayment of claim 4 wherein the pressure
sensitive adhesive layer is less than about 10 microns thick.
10. The roofing underlayment of claim 4 wherein the pressure
sensitive adhesive layer is preferably less than about 5 microns
thick.
11. The roofing underlayment of claim 4 wherein the underlayment
width is less than about 30 inches.
12. A roofing underlayment comprising at least one support layer
having first and second opposite major surfaces, and a filled
textured binder layer attached to said first major surface of said
at least one support layer, such that upon application of said
underlayment to a roof, said filled textured binder layer provides
a skid resistant surface for foot traffic thereon.
13. The underlayment of claim 12 wherein the filler is
substantially coated with the binder
14. The roofing underlayment of claim 12, wherein said at least one
support layer is a woven or non-woven fabric.
15. The roofing underlayment of claim 12, wherein said at least one
support layer is a polyolefin film.
16. The roofing underlayment of claim 12, wherein said at least one
support layer comprises spun bonded polypropylene or woven
polpropylene.
17. The roofing underlayment of claim 12, wherein said binder is a
pressure sensitive adhesive comprising a rubber selected from the
group consisting of styrene/isoprene/styrene block copolymers,
styrene-butadiene-styrene block copolymers,
styrene-ethylene-butylene-styrene block copolymers,
styrene/butadiene rubber, natural rubber, silicone rubber, butyl
rubber, polyisoprene, polyisobutylene, chloroprene,
ethylene-propylene rubber, ethylene alpha olefin, polybutadiene,
nitrile rubbers, and acrylic rubber.
18. The roofing underlayment of claim 12, wherein said binder is a
non-pressure sensitive rubber selected from the group consisting of
styrene/isoprene/styrene block copolymers,
styrene/butadiene/styrene block copolymers,
styrene/ethylene/butylene/styrene block copolymers,
styrene/butadiene rubber, natural rubber, silicone rubber, butyl
rubber, polyisoprene, polyisobutylene, chloroprene,
ethylene-propylene rubber, ethylene alpha olefin, polybutadiene,
nitrile rubbers, thermoplastic polyurethanes (TPUs), thermoplastic
polyolefins (TPOs), and acrylic rubber.
19. The roofing underlayment of claim 12, wherein said binder is a
resin selected from the group including hydrocarbon resins, C-5
hydrocarbon resins, C-9 hydrocarbon resins, (C-5).sub.2 hydrocarbon
resins, rosin acids, rosin esters, terpene resins, coumarone indene
resins, phenol formaldehyde resins, urea formaldehyde resins,
melamine resins, polyester resins, acrylic resins, alkyd resins,
and bitumen.
20. The roofing underlayment of claim 12 wherein the filled
textured binder layer comprises a filler and the volume percent of
filler is more than about 25 percent.
21. The roofing underlayment of claim 12 wherein the filled
textured binder adhesive layer comprises a filler and the volume
percent of filler is preferably more than about 45 percent.
22. The roofing underlayment of claim 12 wherein the average filler
particle size is less than about 100 microns
23. The roofing underlayment of claim 12 wherein the average
particle size is less than about 50 microns.
24. The roofing underlayment of claim 12 wherein the average filler
particle size is less than about 25 microns.
25. The roofing underlayment of claim 12 wherein the volume of
coating is less than about 10 cc/ft2.
26. The roofing underlayment of claim 12 wherein the volume of
coating is less than about 5 cc/ft2.
27. The roofing underlayment of claim 12 wherein the volume of
coating is less than about 2 cc/ft2.
28. The roofing underlayment of claim 12 wherein the filler is
inorganic or organic,
29. The roofing underlayment of claim 12 wherein the filler is
hydratable.
30. The roofing underlayment of claim 12 wherein the width of the
underlayment is less than about 30 inches.
31. A flexible, rollable roofing underlayment comprising at least
one support layer having first and second opposite major surfaces,
and a pressure sensitive adhesive layer or a filled textured binder
layer attached to said first major surface of said at least one
support layer, such that upon application of said underlayment to a
roof by unrolling, said filled textured binder layer provides a
skid resistant surface for foot traffic thereon, and a pressure
sensitive adhesive attached to said second major surface of said at
least one support layer such that upon application of said
underlayment to a roof the membrane is adhered to said roof.
32. The underlayment of claim 31 wherein said support layer is a
cross-laminated high density polyethylene film
33. The underlayment of claim 31 wherein the pressure sensitive
adhesive attached to said second major face of said at least one
support layer comprises rubber and bitumen.
34. A rigid product comprising a rigid substrate selected from
plywood or oriented strand board having the non-skid surface of
claim 1.
35. A roofing underlayment positioned between a roof support
structure and an overlayment, comprising at least one support layer
having first and second opposite major surfaces, said first major
surface abutting said roof support structure, and a pressure
sensitive layer or a filled textured binder layer attached to said
second major surface of said at least one support layer, such that
upon application of said overlayment to said roof and over said
underlayment, said pressure sensitive layer provides a skid
resistant surface for foot traffic thereon.
36. The roofing underlayment of claim 35, wherein said at least one
support layer is a woven or non-woven fabric.
37. The roofing underlayment of claim 35 wherein said at least one
support layer is a polyolefin film.
38. The roofing underlayment of claim 35 wherein said at least one
support layer comprises spun bonded polypropylene.
39. The roofing underlayment of claim 35 wherein said pressure
sensitive layer comprises a rubber selected from the group
consisting of styrene/isoprene/styrene copolymer,
ethylene/butylene/styrene block copolymer, styrene butadiene
rubber, natural rubber, silicone, butyl rubber, isoprene, butadiene
and acrylic rubber.
40. The roofing underlayment of claims 35 wherein the support layer
in said underlayment comprises one or more layers of polymer and
one or more layers of fabric.
41. A method of waterproofing a roof, comprising the steps of: 1)
providing a roof deck; 2) providing a roll of roof underlayment
comprising at least one support layer having a skid-resistant
coating therein comprising a layer of pressure sensitive adhesive
or filled textured binder; and 3) unrolling said underlayment and
applying it to said roof deck.
42. The method of claim 41, wherein said underlayment is applied to
said roof deck by mechanical fastening.
43. The method of claim 41, wherein said underlayment is applied to
said roof deck by adhesively adhering said underlayment to said
deck.
44. An article comprising a product packaged within a flexible
packaging, said packaging having the non-skid surface of claim 1
coated on its exterior.
45. An organic or inorganic roofing felt coated having as its
exterior surface, the non-skid surface of claim 1.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to skid-resistant surfaces
especially when wet, and in particular to skid-resistant
trafficable surfaces such as roofs and floors as well as skid
resistant packaging for lumber and the like.
BACKGROUND OF THE INVENTION
[0002] Roofing underlayments are typically installed over the roof
deck and under the primary roof covering or overlayment, which can
be asphalt shingles, metal shingles, or metal roofing, tiles such
as Spanish or slate tile, wood shakes, concrete, slate, etc. The
underlayment provides a secondary moisture barrier to protect the
roof deck and building interior from moisture that may penetrate
through the primary roof covering. Commercially effective
underlayments must maintain their strength and integrity even after
exposure to the elements. Underlayments are used both in new
construction and in re-roofing projects.
[0003] It is known in the waterproofing art to combine a pre-formed
waterproofing membrane, such as a rubberized bitumen/oil layer,
with a carrier support sheet or film, and to utilize this as an
underlayment The carrier support film may comprise a variety of
materials, such as rubber, plastic, and/or metal, or combinations
of the same. The use of metals is desirable, for example, to
improve dimensional stability of the support film, which is
subjected to oil migration from the oil-plasticized bitumen layer.
It has also been desirable to employ cross-laminated plastic films,
such as high density polyethylene, for improved stability of the
carrier support sheet.
[0004] Such pre-formed waterproofing membrane laminates are
considered "sheet-like" because they are sufficiently flexible that
they can be rolled up and transported after manufacture to the job
site where they are unrolled and installed on the building surface.
This kind of membrane laminate, useful as an underlayment on sloped
roofs, is commercially available from Grace Construction Products
(W.R. Grace & Co.-Conn) under the name "ICE & WATER SHIELD"
(a registered trademark of W.R.Grace & Co.-Conn.) The
underlayment is applied to the roof deck before installation of the
overlayment. The function of the membrane underlayment is to seal
around roofing fasteners and to protect against damage from ice
dams and wind-driven rain.
[0005] Another commercially available example of an underlayment is
"TRI-FLEX 30", (a product also available from Grace Construction
Products) which is spun-bonded polypropylene coated with a thin
layer of U.V. stabilized polypropylene on both of its surfaces.
[0006] In addition to its water shedding capabilities, an important
characteristic of a roofing underlayment is its skid or slip
resistance. Since roofing applicators must walk on the underlayment
during roofing installation, the exposed surface should have a
sufficiently high coefficient of friction, even when wet, so as to
minimize or prevent an applicator from slipping when walking or
standing on the surface.
[0007] It is also desirable that the roofing underlayment be
rollable for ease of transportation and handling, and be readily
unrollable, ideally by a single person, for application. However,
maintaining unrollability while providing sufficient skid
resistance can be problematic, particularly where the skid
resistance is due to the tackiness or stickiness of the walking
surface. That is, the same tackiness that is advantageously used to
provide skid resistance can make it difficult or impossible to
unroll the underlayment, particularly if the unrolling is to be
carried out by only one person.
[0008] It is also desirable that the underlayment be light in
weight, i.e. low weight per unit area. Lightweight provides for
easier transportation to the roofdeck and easier installation.
There are fewer trips up a ladder to a roofdeck with a lightweight
membrane as compared to a heavier membrane. Some underlayments
comprise a heavy layer of a large particulate that provides for a
heavyweight membrane.
[0009] It therefore would be desirable to provide a lightweight
roofing underlayment having excellent skid resistance while
maintaining unrollability.
SUMMARY OF THE INVENTION
[0010] One embodiment of the invention is the provision of a
skid-resistant surface comprising a substrate coated with a skid
resistant layer. The substrate is preferably a pedestrian
trafficable surface such as a roofing or flooring surface. The skid
or slip-resistant layer is preferably a pressure sensitive adhesive
or a highly filled textured binder.
[0011] Another embodiment of the invention is a lightweight roofing
underlayment having excellent skid or slip-resistance to foot
traffic under dry, wet and/or dusty conditions on a sloped surface,
and is both readily rollable and unrollable as a coherent unit. The
present invention overcomes problems associated with the prior art.
The underlayment is preferably a multi-layered sheet material that
includes a support layer composed of a film or fabric or both, and
a skid or slip resistant layer on one or both faces of the support
layer. The skid or slip resistant layer is preferably a pressure
sensitive adhesive or a highly filled textured binder. The
resulting sheet-like underlayment is sufficiently flexible to allow
it to be formed into rolls and readily installed by unrolling over
a support structure such as a roof deck. It also provides a sloped
walking surface having a high coefficient of friction and excellent
skid resistance even when wet and/or dusty, and even at high roof
pitches such as those between about 4:12 and 12:12.
[0012] In its method aspects, the present invention relates to a
method of forming a skid-resistant surface useful for example as a
roofing underlayment by coating a thin layer of a pressure
sensitive adhesive or a filled textured binder to a support layer
such as a film or fabric, and to a method of waterproofing a roof
or floor by unrolling the underlayment and applying it to the roof
or floor such as by mechanical fastening or with an adhesive.
[0013] Another embodiment of the invention is an organic or
inorganic roofing felt coated with a pressure sensitive adhesive or
a highly filled textured binder.
[0014] Another embodiment of the invention is an exposed roofing
membrane coated with a pressure sensitive adhesive or a highly
filled textured binder.
[0015] Another embodiment of the invention is a roof decking
comprising plywood or other decking material such as oriented
strand board coated with a pressure sensitive adhesive or a highly
filled textured binder.
[0016] Another embodiment of the invention is non-skid flexible
packaging comprising a support layer coated with a pressure
sensitive adhesive or a highly filled textured binder.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a schematic diagram of a roofing underlayment in
accordance with one embodiment of the present invention;
[0018] FIG. 2 is a schematic diagram of a roofing underlayment in
accordance with another embodiment of the present invention;
[0019] FIG. 3 is a schematic diagram of a roofing underlayment in
accordance with yet another embodiment of the present
invention;
[0020] FIG. 4 is a schematic diagram of a roofing underlayment in
accordance with still another embodiment of the present
invention;
[0021] FIG. 5 is a schematic diagram of a roofing underlayment in
accordance with a still further embodiment of the present
invention;
[0022] FIG. 6 is a schematic diagram of a roofing underlayment in
accordance with yet another embodiment of the present
invention;
[0023] FIGS. 7A-7C are photomicrographs of a non-skids surface of
the invention comprising a filled textured binder, looking down
from above at the surface;
[0024] FIG. 8 is a schematic of a Meyer rod coater;
[0025] FIG. 9 is a schematic of a modified Meyer rod coater;
[0026] FIG. 10 is a schematic of a gravure coater;
[0027] FIG. 11 is a plot of adhesion value, a measure of blocking,
versus adhesive coating thickness for an SIS pressure sensitive
adhesive on various membranes;
[0028] FIG. 12 is a plot of adhesion value, a measure of blocking,
versus adhesive coating thickness for an acrylic pressure sensitive
adhesive on various membranes;
[0029] FIG. 13 is a plot of adhesion value, a measure of blocking,
versus adhesive coating thickness for an SEBS pressure sensitive
adhesive on various membranes;
[0030] FIG. 14 is a plot of adhesion value, a measure of blocking,
versus membrane type for a filled acrylic pressure sensitive
adhesive;
[0031] FIG. 15 is a plot of adhesion value, a measure of blocking,
versus coating volume for a filled SEBS pressure sensitive adhesive
on various membranes; and
[0032] FIG. 16 is a plot of adhesion value, a measure of blocking,
versus coating volume for a filled SEBS pressure sensitive adhesive
at various loadings of filler by volume.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0033] One embodiment of the invention is a skid-resistant surface
comprising a substrate coated with a skid resistant layer that is
skid resistant particularly when wet. The skid or slip resistant
layer is preferably a pressure sensitive adhesive or a highly
filled textured binder. The substrate may be a pedestrian
trafficable surface such as roofing surfaces and flooring surfaces.
Roofing surfaces include rollable roofing underlayments including
synthetic polymeric mechanically attached underlayments, synthetic
polymeric adhesively attached underlayments, organic and inorganic
asphalt saturated roofing felts, liquid-applied roofing surfaces
including urethanes, asphaltic-based materials, acrylics, and
silicones, etc. Roofing surfaces further may be rollable exposed
roofing membranes including rubber sheets, vinyl sheets, and TPO
sheets. Flooring surfaces include wood-based materials, Portland
cement-based materials, ceramic materials, naturally occurring
stone materials, and synthetic polymeric materials as well as
composite materials containing combinations of the foregoing.
[0034] Suitable pressure sensitive adhesive layers comprise rubbers
such as those selected from the group consisting of SIS
(styrene-isoprene-styrene block copolymers), SBS
(styrene-butadiene-styrene block copolymers), SEBS
(styrene-ethylene-butylene-styrene block copolymers), SBR, natural
rubber, silicone rubber, butyl rubber, polyisoprene,
polyisobutylene, chloroprene, ethylene-propylene rubber, ethylene
alpha olefin, polybutadiene, nitrile rubbers, and acrylic rubber. A
rubber modified bitumen pressure sensitive adhesive may also be
used. All of the rubbers listed above, except silicone, may be
blended with bitumen to produce a pressure sensitive adhesive.
Preferably the pressure sensitive adhesive comprises a weatherable
rubber such as those selected from the group consisting of SEBS,
acrylic, silicone, and butyl. Preferably the pressure sensitive
adhesive used is free of surfactant, since the presence of
surfactant tends to reduce the skid resistance when the surface is
wet.
[0035] The pressure sensitive adhesive generally comprises a
rubber, a tackifier, and a plasticizer. The plasticizer and
tackifier modify the properties of the rubber to make it pressure
sensitive. A plasticizer is generally a low molecular weight
ingredient that is compatible with the rubber. It lowers the
plateau modulus of a mixture of rubber and plasticizer vs. the
rubber alone. A tackifier is generally a low molecular weight
ingredient that is compatible with the rubber and exhibits a high
glass transition temperature vs. the rubber. It lowers the plateau
modulus of a mixture of rubber and tackifier vs. the rubber alone,
and the glass transition temperature of the blend of tackifier and
rubber is higher than rubber alone. These features are known to
those skilled in the art of pressure sensitive adhesive
formulation.
[0036] The pressure sensitive adhesive may comprise rubber alone.
Such is the case for some acrylic polymers such as butyl acrylate
and ethyl-hexyl acrylate that are inherently pressure
sensitive.
[0037] Preferably the pressure sensitive adhesive layer is used in
a thickness of less than or equal to about 10 microns, more
preferably less than or equal to about 5 microns. Use of such a
thin pressure sensitive layer insures good skid-resistance,
including wet skid-resistance, while insuring that a pedestrian
does not become stuck to the surface while walking.
[0038] For embodiments where the skid-resistant layer is a pressure
sensitive adhesive the pressure sensitive adhesive exhibits a
minimum peel adhesion value of 1 pound per linear inch (pli) to the
substrate. Adhesion is measured by applying a one inch wide tape
comprising a 5 mil layer of the pressure sensitive adhesive
laminated to the face of a 4 mil thick cross-laminated, high
density polyethylene sheet such as "Valeron", a commercial product
of Valeron Strength Films, to the substrate. This "tape" may be
prepared by coating the pressure sensitive adhesive from solution
and drying, or coating the molten pressure sensitive adhesive at
elevated temperature onto the 4 mil Valeton. The face of the
pressure sensitive adhesive side of the one inch wide tape is
applied to the substrate. The construction is rolled in four times
in one second passes with a 30 pound roller. Adhesion is measured
fifteen minutes later with a mechanical test device such as an
Instron. The peel angle is 90 degrees. The cross-head speed is
2''/min.
[0039] In the embodiment where the skid-resistant layer is a filled
textured binder the binder is a material that adheres to both the
filler and the substrate, as described in a test below, and is
organic solvent soluble. Preferred binders include: pressure
sensitive adhesives as described above for a skid resistant layer
comprising only a pressure sensitive adhesive, rubbers, and resins.
Another preferred binder comprises an amorphous polyolefin such as
that produced by Eastman Chemical under the trade name
"Eastoflex".
[0040] For binders that comprise a rubber the rubber is selected
from the group consisting of SIS (styrene-isoprene-styrene block
copolymers), SBS (styrene-butadiene-styrene block copolymers), SEBS
(styrene-ethylene-butylene-styrene block copolymers), SBR, natural
rubber, silicone rubber, butyl rubber, polyisoprene,
polyisobutylene, chloroprene, ethylene-propylene rubber, ethylene
alpha olefin, polybutadiene, nitrile rubbers, thermoplastic
polyurethanes (TPUs), thermoplastic polyolefins (TPOs), and acrylic
rubber. Preferably the rubber is weatherable such as those selected
from the group consisting of SEBS, acrylic, silicone, and butyl.
Preferably the rubber used is free of surfactant, since the
presence of surfactant tends to reduce the skid-resistance when the
surface is wet.
[0041] For binders that comprise a resin, the resin may be selected
from a group of materials including hydrocarbon resins, C-5
hydrocarbon resins, C-9 hydrocarbon resins, (C-5).sub.2 hydrocarbon
resins, rosin acids, rosin esters, terpene resins, coumarone indene
resins, phenol formaldehyde resins, urea formaldehyde resins,
melamine resins, polyester resins, acrylic resins, alkyd resins,
bitumen, aldehyde & ketone resins, amides & polyamides,
amines & polyamines, maleic resins, melamine resins, oxazole
resins, phenolic resins, phenoxy resins, phthalic anhydrides,
styrene resins, urea resins, vinyl resins. Preferably, the resin
has a Tg or ring and ball softening point that is greater than or
exceeds 75F. More preferably the resin has a Tg or ring and ball
softening point that is greater than or exceeds 140F.
[0042] Adhesion of the filled textured binder to the substrate is
measured in a peel adhesion test using a pre-formed pressure
sensitive tape. A 2'' wide preformed tape, (commercially available
as "Preprufe", a registered trademark of W.R. Grace &
Co.-Conn.) is applied to the non-skid coated substrate. The sample
is rolled 4 times, at 1 second per pass, with a 30 lb roller.
Adhesion is measured in a T-peel adhesion test 15 min after rolling
at a crosshead speed of 2'' per minute with an Instron mechanical
tester. The peel adhesion value must be greater than 1 pound per
linear inch ("pli"). Preferably, the adhesion value is greater than
2 pounds pli.
[0043] In the embodiment where the skid-resistant layer is a filled
textured binder the filler particles, including those on the
exterior surface of the coating, are preferably substantially
coated with binder and the coating is textured. "Substantially"
coated means that at least about 95 percent of the filler's surface
is coated. By "textured" is meant that the filler particles
protrude from the surface and thus the surface coating is uneven
and not smooth or planar. Such a textured surface is shown in FIGS.
7A-7C where the individual particles of coated filler are visually
detectable in an SEM photomicrograph. The filler particles must be
substantially coated with binder as a result of the preferred
manufacturing process. This preferred process involves producing a
coating comprising the binder, the filler, and a solvent that
dissolves the binder, applying the coating to a substrate, and
removing the solvent by evaporation thereby depositing a layer of
coating on the filler particles.
[0044] In the embodiment where the skid-resistant layer is a filled
textured binder, the filler is inorganic or organic and is used in
an amount of at least about 25 percent by volume of the filled
textured binder. In a preferred embodiment the filler is inorganic
or organic and is used in an amount of greater than or equal to
about 45 percent by volume. Use of a high filler volume insures
that the filled binder is textured. If the filler volume is too low
the layer is relatively smooth. The filler has a maximum average
particle size of less than about 100 microns. Preferably the filler
has a maximum average particle size of up to about 50 microns. More
preferably the filler has a maximum average particle size up to
about 25 microns. The term "particles" as used herein is intended
to encompass particles having regular (e.g., spherical) or
irregular shapes, as well as shards. Suitable inorganic fillers
include calcium carbonate, silica, clay, talc, vermiculite, mica,
titanium dioxide, fly ash, alumina trihydrate, and slag The coating
volume of the filled textured binder layer is less than 10 cc/ft2,
more preferably less than about 5 cc/ft2, and most preferably less
than about 2 cc/ft2.
[0045] Inorganic particulates that react with water may also be
used. These include Portland cement calcium oxide, high-alumina
cement, blast furnace slag, pozzolanas, and pozzolanic cement.
These fillers may hydrate after the underlayment is installed on
the roof deck. The net effect is an increase in the average size of
the particulate after the membrane is installed.
[0046] The skid-resistant surfaces are applied to a substrate as an
organic solvent-based coating. For a pressure sensitive adhesive
non-skid surface the coating comprises a pressure sensitive
adhesive and an organic solvent. For a filled textured binder
non-skid surface the coating comprises a binder, filler, and an
organic solvent. The coatings may be applied to a substrate by
brush, roller, or spray application. The solvent evaporates leaving
the non-skid coating. Continuous processes for coating a substrate
are also contemplated. These processes include spray, roll coating,
gravure coating, and knife coating.
[0047] Another embodiment of the invention is a roofing
underlayment comprising a woven fabric, a non-woven fabric, a film,
or a combination of these and a skid-resistant layer comprising a
pressure sensitive adhesive or a highly filled textured binder.
[0048] The preferred underlayments to which a skid resistance layer
is added comprises a spun bonded polypropylene substrate, both
sides of which have been extrusion coated with a polyolefin, and an
underlayment comprising a woven fabric that is laminated to a
polyolefin film.
[0049] Turning first to FIG. 1, there is shown one embodiment of
the underlayment 10 of the present invention. The underlayment 10
has an uppermost layer 13 of the skid-resistant layer of the
invention supported by a support layer which can be one or more
layers of a film or fabric, or both. In the embodiment shown in
FIG. 1, the support layer is comprised of a lowermost layer 11 of
fabric and intermediate layer 12 of film. Suitable films 12 are
those comprised of a synthetic organic polymer such as a polyolefin
or a blend of polyolefins, and films mentioned as suitable for this
layer hereinafter. The preferred film is polypropylene or
polyethylene or films made from mixtures of such. The present
invention also contemplates the use of more than one film layer,
such as layers laminated and/or co-extruded or cross-laminated
together. Those skilled in the art will appreciate that the
underlayments can be produced by any method known in the art such
as extrusion, lamination and calendaring. The film layer 12 has a
thickness in the range from 0.5 mils to 10 mils. Preferably, the
thickness is in the range from 1 mil to 3 mils.
[0050] Suitable fabrics for use in the support layer 11 include
both natural and synthetic woven and non-woven fabrics, and
preferably is synthetic such as a polyolefin, such as polypropylene
or polyethylene, a polyester, etc., or glass. Preferably the woven
fabric has less than or equal to 25 percent open space. Woven and
non-woven fabrics exhibit a weight ranging from 0.5 oz/yd2 to 10
oz/yd2. Preferably, woven and non-woven fabrics exhibit a weight in
the range from 1 oz/yd2 to 3 oz/yd2.
[0051] In the particular embodiment of FIG. 1, as mentioned the
support layer is comprised of (i) a non-woven or woven fabric layer
11, and (ii) a synthetic organic polymer film 12 attached to one
surface of the fabric 11. On the surface of the synthetic organic
polymer film 12 is a skid-resistance layer 13, which is a pressure
sensitive adhesive or a highly filled textured binder. It is this
skid-resistance layer 13 that provides the walking surface for the
roof applicator, and is ultimately covered by the primary roof
covering or overlayment such as shingles or tiles.
[0052] In the case where fabric layer 11 is a non-woven fabric, it
may be comprised of one or more synthetic organic polymers such as
polyolefins, for example polypropylene or polyethylene, or may be
comprised of polyester. Polypropylene is preferred. Where fabric
layer 11 is a woven fabric, it may be comprised of one or more one
or more synthetic polymers such as polyolefins, for example
polypropylene, or polyethylene, or may be comprised of polyester.
The fabric may also comprise a woven or non-woven glass fiber mat.
Fabrics comprised of polypropylene are preferred for use in the
embodiment shown in FIG. 1.
[0053] The synthetic polymer film 12 as aforementioned comprises
one or more polymers such as polyolefins, for example
polypropylene, polyethylene, a polymer comprising ethylene and
propylene, a polymer comprising ethylene and methyl acrylate, a
polymer comprising ethylene and ethyl acrylate, a polymer
comprising ethylene and butyl acrylate, a polymer comprising
ethylene and an alpha olefin, a polymer comprising ethylene and
vinyl acetate or polyester, and includes mixtures of the foregoing.
Polyethylene, polypropylene, and mixtures of the two are preferred.
The synthetic polymer film 12 may also be a coextruded film layer
(not shown as such in FIG. 1). Each layer may comprise one or more
of the polymers listed above.
[0054] The laminate comprising the non-woven or woven fabric 11
attached to a synthetic organic polymer film 12 may be manufactured
by extrusion coating the layer 12 as a polymer melt onto the
fabric.
[0055] Suitable pressure sensitive adhesive layers 13 comprise
rubbers such as those selected from the group consisting of SIS
(styrene-isoprene-styrene block copolymers), SBS
(styrene-butadiene-styrene block copolymers), SEBS
(styrene-ethylene-butylene-styrene block copolymers), SBR, natural
rubber, silicone rubber, butyl rubber, polyisoprene,
polyisobutylene, chloroprene, ethylene-propylene rubber, ethylene
alpha olefin, polybutadiene, nitrile rubbers, and acrylic rubber. A
rubber modified bitumen pressure sensitive adhesive may also be
used. All of the rubbers listed above, except silicone, may be
blended with bitumen to produce a pressure sensitive adhesive.
Preferably the pressure sensitive adhesive comprises a weatherable
rubber such as those selected from the group consisting of SEBS,
acrylic, silicone, and butyl. Preferably the pressure sensitive
adhesive used is free of surfactant, since the presence of
surfactant tends to reduce the skid resistance when the surface is
wet.
[0056] A pressure sensitive adhesive generally comprises a rubber,
a tackifier, and a plasticizer. The plasticizer and tackifier
modify the properties of the rubber to make it pressure sensitive.
A plasticizer is generally a low molecular weight ingredient that
is compatible with the rubber. It lowers the plateau modulus of a
mixture of rubber and plasticizer vs. the rubber alone. A tackifier
is generally a low molecular weight ingredient that is compatible
with the rubber and it exhibits a high glass transition temperature
vs. the rubber. It lowers the plateau modulus of a mixture of
rubber and tackifier vs. the rubber alone, and the glass transition
temperature of the blend of tackifier and rubber is higher vs.
rubber alone. These features are known to those skilled in the art
of pressure sensitive adhesive formulation.
[0057] The pressure sensitive adhesive may comprise rubber alone.
Such is the case for some acrylic polymers such as butyl acrylate
and ethyl-hexyl acrylate that are inherently pressure
sensitive.
[0058] Preferably the pressure sensitive adhesive layer 13 is used
in a thickness of less than or equal to about 10 microns, more
preferably less than or equal to about 5 microns. Use of such a
thin pressure sensitive layer insures good skid resistance,
including wet skid resistance, while maintaining the ability to
unroll the membrane.
[0059] For embodiments where the non-skid layer 13 is a pressure
sensitive adhesive, the pressure sensitive adhesive exhibits a
minimum peel adhesion value of 1 pound per linear inch (pli) to the
support sheet. Adhesion is measured by applying a tape comprising a
5 mil layer of the pressure sensitive adhesive to the face of the
support sheet in contact with the non-skid layer. This "tape" may
be prepared by coating the pressure sensitive adhesive from
solution and drying or coating the molten pressure sensitive
adhesive at elevated temperature on to the support sheet. The face
of a 1'' wide tape comprising the pressure sensitive adhesive is
applied to the face of another layer of support sheet. The
"sandwich" is rolled in 4-1 sec. passes with a 30 pound roller.
Adhesion is measured fifteen minutes later with a mechanical test
device such as an Instron. The peel angle is 180 degrees. The
cross-head speed is 2''/min.
[0060] In the embodiment where the skid resistant layer 13 is a
filled textured binder the binder is a material that adheres to
both the filler and the support sheet, as described in a test
below, and is organic solvent soluble. Preferred binders include:
pressure sensitive adhesives as described above for a skid
resistant layer comprising only a pressure sensitive adhesive,
rubbers, and resins. Another preferred binder comprises an
amorphous polyolefin like those produced by Eastman Chemical under
the trade name of Eastoflex.
[0061] For binders that comprise a rubber the rubber is selected
from the group consisting of SIS (styrene-isoprene-styrene block
copolymers), SBS (styrene-butadiene-styrene block copolymers), SEBS
(styrene-ethylene-butylene-styrene block copolymers), SBR, natural
rubber, silicone rubber, butyl rubber, polyisoprene,
polyisobutylene, chloroprene, ethylene-propylene rubber, ethylene
alpha olefin, polybutadiene, nitrite rubbers, thermoplastic
polyurethanes (TPUs), thermoplastic polyolefins (TPOs), and acrylic
rubber. Preferably the rubber is weatherable such as those selected
from the group consisting of SEBS, acrylic, silicone, and butyl.
Preferably the rubber used is free of surfactant, since the
presence of surfactant tends to reduce the skid resistance when the
surface is wet.
[0062] For binders that comprise a resin the resin may be selected
from a group of materials including hydrocarbon resins, C-5
hydrocarbon resins, C-9 hydrocarbon resins, (C-5).sub.2 hydrocarbon
resins, rosin acids, rosin esters, terpene resins, coumarone indene
resins, phenol formaldehyde resins, urea formaldehyde resins,
melamine resins, polyester resins, acrylic resins, alkyd resins,
bitumen, aldehyde & ketone resins, amides & polyamides,
amines & polyamines, maleic resins, melamine resins, oxazole
resins, phenolic resins, phenoxy resins, phthalic anhydrides,
styrene resins, urea resins, vinyl resins. Preferably, the resin
has a Tg or ring and ball softening point that is greater than or
exceeds 75F. More preferably the resin has a Tg or ring and ball
softening point that is greater than or exceeds 140F.
[0063] Adhesion of the filled textured binder to the support sheet
is measured in a peel adhesion test using a pre-formed pressure
sensitive tape. A 2'' wide preformed tape. Preprufe.RTM. Tape, is
applied to the non-skid coated face of the underlayment. The sample
is rolled 4 times, at 1 second per pass, with a 30 lb roller.
Adhesion is measured in a T-peel adhesion test 15 min after rolling
at a cross head speed of 2'' per minute with an Instron mechanical
tester. The peel adhesion value must be greater than 1 pound per
linear inch (pli). Preferably, the adhesion value is greater than 2
pounds per linear inch.
[0064] As mentioned previously, in the embodiment where the skid
resistant layer 13 is a filled textured binder the filler
particles, including those on the exterior surface of the coating,
are preferably substantially coated with binder and the coating is
textured. This texturing is clearly visible. See FIGS. 7A to 7C for
an illustration. The ability to visually detect particles in an SEM
photomicrograph is one test for an embodiment of the invention
comprising a filled textured binder. The filler particles must be
coated with binder as a result of the preferred manufacturing
process. This involves producing a coating comprising the binder,
the filler, and a solvent that dissolves the binder, applying the
coating to a substrate, and removing the solvent by evaporation
thereby depositing a layer of coating on the filler particles.
[0065] As mentioned, in the embodiment where the skid resistant
layer 13 is a filled textured binder, the filler is inorganic or
organic and is used in an amount of at least about 25 percent by
volume of the filled textured binder. In a preferred embodiment the
filler is inorganic or organic and is used in an amount of at least
about 45 percent by volume. Use of a high filler volume insures
that the filled binder is textured. If the filler volume is too low
the layer is relatively smooth. The filler has a maximum average
particle size of up to about 100 microns. Preferably the filler has
a maximum average particle size of less than about 50 microns. More
preferably the filler has a maximum average particle size of up to
about 25 microns. Larger particle sizes hinder the coating
application process, and add excessive weight to the underlayment.
The term "particles" as used herein is intended to encompass
particles having regular (e.g., spherical) or irregular shapes, as
well as shards. Suitable inorganic fillers include calcium
carbonate, silica, clay, talc, vermiculite, mica, titanium dioxide,
fly ash, alumina trihydrate, and slag. The coating volume of the
filled textured binder layer is up to about 10 cubic centimeters
per square foot, more preferably less than about 5 cc/ft2, and most
preferably less than about 2 cc/ft2.
[0066] Inorganic particulates that react with water may also be
used. These include Portland cement, calcium oxide, high-alumina
cement, blast furnace slag, pozzolanas, and pozzolanic cement.
These fillers may hydrate after the underlayment is installed on
the roof deck. The net effect is an increase in the average size of
the particulate after the membrane is installed.
[0067] Some underlayments of the present invention are textured at
2 levels. These include embodiments where the support sheet
comprises a woven or a non-woven fabric in direct contact with
non-skid layer 13 or separated from non-skid layer 13 by a thin
polymer film 12. One level of texturing is provided by the filler.
Another level of texturing is provided by the fabric. While not
being bound by theory, it is believed that both levels of texturing
contribute to the performance of the underlayments. The dual
texturing enhances resistance to "blocking" (the tendency of the
front face of the underlayment to stick to its rear face when
unrolled) by minimizing contact between opposite faces of the
underlayment within a roll of underlayment. The dual texturing also
enhances skid resistance by enhancing mechanical interlock between
the surface of the underlayment and the sole of a shoe in contact
with the surface of the underlayment. The dual texturing also
enhances skid resistance by providing channels for lubricant
migration when a shoe sole comes into contact with an underlayment
that is coated with lubricant(s). Lubricants include water and
dirt. To avoid skidding the lubricant must be channeled away from
the contact area between a shoe sole and the surface of the
underlayment.
[0068] The pressure sensitive adhesive layer and the filled
textured binder layer are preferably coated as a solution in an
organic solvent. The organic solvent-based solution of a pressure
sensitive adhesive or filled binder is coated onto a web comprising
the support layer, and the solvent is removed by evaporation. The
resulting web can then be wound into a roll. Suitable organic
solvents include those that will completely dissolve the pressure
sensitive adhesive or the binder and also exhibit a high vapor
pressure so that evaporation can be affected quickly in the coating
process.
[0069] Other methods may be utilized to coat a filled textured
binder on to a support sheet. One option is to coat a solution of
the binder on to the support sheet, apply the filler to the
solution coated web, and remove the solvent by evaporation. Yet
another option is to coat the binder as a molten layer on the
support sheet, apply the filler while the binder is still molten,
and cool to solidify the binder. The manufacturing method where a
mixture of an organic solvent, binder, and filler is coated onto a
web comprising the support layer, and the solvent is removed by
evaporation, is preferred because the filler is well bonded to the
support sheet in comparison to other manufacturing methods by
virtue of being substantially coated with binder.
[0070] FIG. 2 illustrates a second embodiment of the present
invention. The underlayment 21 comprises a non-woven or woven
fabric layer 11, a synthetic organic polymer film layer 12 adhered
to both faces of the fabric 11, and a pressure sensitive adhesive
layer or filled textured binder layer 13 on the surface of the
polymer film 12. The polymer film 12 may be a coextruded layer (not
shown) polymer film.
[0071] Yet another embodiment is shown in FIG. 3, where the
underlayment 22 comprises a non-woven or woven fabric 11, a
synthetic organic polymer film 12 adhered to both faces of the
fabric 11, a pressure sensitive adhesive layer or filled textured
binder layer 13 on the surface of one of the polymer film layers
12, and a further non-skid layer 14 on the surface of the other
polymer film layer 12. The non-skid layer 14 can minimize or
prevent relative movement between the underlayment and the roofing
deck during and after installation. Suitable non-skid layers 14
include one or more polyolefins such as polyethylene,
polypropylene, a polymer comprising ethylene and propylene, a
polymer comprising ethylene and methyl acrylate, a polymer
comprising ethylene and ethyl acrylate, a polymer comprising
ethylene and butyl acrylate, a polymer comprising ethylene and
vinyl acetate, a polymer comprising ethylene and an alpha olefin,
and a polymer comprising ethylene and octene. The non-skid layer 14
preferably has a thickness of less than about 1 mil, and exhibits a
Shore D hardness, ASTM D2240, of less than about 45.
[0072] The multi-layer synthetic organic polymer film 12 and 14 in
FIG. 3 may be co-extrusion coated onto the fabric 11 to produce a
structure comprising layers 11, 12 and 14 of underlayment 22.
Synthetic polymer layer 12 is extrusion coated to the other face of
fabric 11. This may also be a coextruded layer (not shown) The
non-skid layer 13 then may be applied to such structures to produce
the underlayment of FIG. 3 by coating, as a mixture with an organic
solvent that dissolves the organic portion of the coating, onto a
web comprising a support in a continuous web coating operation. The
solvent is removed by evaporation and the resulting underlayment is
wound into rolls. Various types of coaters may be used to apply the
organic solvent based coating, including wire wound rod (also
called Meyer rod), roll coater, gravure coater, air knife, and a
knife over roll coater.
[0073] FIG. 8 is a schematic of "Meyer" rod coating using a wire
wound rod, the preferred coating method used herein. In Meyer rod
coating, a coating roll 31 is situated in a bath 30 filled with
coating. A layer of coating is deposited on the coating roll 31 as
the roll is rotated. Coating from the roll is transferred to the
web 34 comprising the support sheet. The wire-wound metering rod 32
sometimes known as a "Meyer Bar", allows the desired quantity of
the coating to remain on the substrate 34. The excess coating is
deposited back into the pan 30. The quantity metered on to the
substrate is determined by the diameter of the wire used on the
rod. For coatings comprising a highly filled textured binder the
machine design may be modified to accommodate potential problems
with filler settling during the coating process. Filler may tend to
settle in the bath 30 of FIG. 8. This is particularly important
when a low viscosity coating is applied. One option is to
recirculate the coating in the pan. This may be facilitated with a
tapered pan 25 design and recirclation system 36 and 37 as shown in
FIG. 9.
[0074] FIG. 10 shows a schematic of gravure coating. The gravure
coater depends on an engraved roller 38 running in a coating bath
that fills the imprinted dots or lines of the roller with the
coating material. The excess coating on the roller is removed by
the doctor blade and the coating is then deposited onto the
substrate as it passes through the engraved roller and a pressure
roller. As immediately applied to the web, the coating is textured.
If the coating viscosity is low and or solvent evaporation is slow,
the textured pattern levels to produce a smooth coating except for
filler particles that are thicker than the binder layer. If the
coating viscosity is high and or solvent evaporation is fast, then
a textured pattern results after solvent evaporation. This may be
affected for a non-skid layer comprising a pressure sensitive
adhesive (no filler) or a filled textured binder. For a non-skid
layer comprising a filled textured binder the net effect is to have
2 levels of texturing. The smaller-scale texturing is contributed
by the filler particles. The larger-scale texturing is related to
the gravure roll pattern.
[0075] FIG. 4 illustrates a further embodiment 23 that comprises a
woven fabric layer 15 with less than or equal to 25 percent open
space, a pressure sensitive adhesive layer or filled textured
binder layer 13, a lamination layer 20, a polymer film 16 and a
second non-skid layer 14. Layer 15 comprises a material selected
from a list including polyethylene, polypropylene, polyester, or
glass. The weight of layer 15 is 0.5 oz/yd2 to 10 oz/yd2.
Preferably, the weight of layer 15 is 1 oz/yd2 to 3 oz/yd2. Options
for materials for layer 14 are described above. Layer 16 is a
polymer film comprising one or more materials selected from a list
including polypropylene, polyethylene, a polyolefin, or polyester.
The thickness of layer 16 is 0.5 mils to 10 mils. Preferably the
thickness of layer 16 is 1 to 3 mils. Polypropylene is preferred.
Layer 20 adheres layer 15 to layer 16. Layer 20 may comprise the
same materials as previously described above for layer 12. The film
layer 20 has a thickness in the range from 0.5 mils to 10 mils.
Preferably, the thickness of layer 20 is in the range from 1 mil to
3 mils.
[0076] Layer 20 may also comprise a pressure sensitive adhesive as
described above for layer 13. Layer 20 may also comprise bitumen.
Layer 20 may also comprise rubber and bitumen. For the case where
layer 20 comprises a pressure sensitive adhesive, bitumen, or
bitumen and rubber, the thickness is in the range from 1 mil to 50
mils. For the case where layer 20 comprises a pressure sensitive
adhesive, bitumen, or bitumen and rubber the underlayment 23
exhibits nail sealing characteristics, i.e. the material of layer
20 tends to seal around nails that are made to penetrate the
underlayment 23.
[0077] The underlayment 23 of FIG. 4 may be made in several ways. A
preferred process is described as follows. A coextruded film
comprising layers 14 and 16 is made in a coextrusion process. Next
the coextruded film 14/16 is laminated to woven fabric 15 via
extrusion lamination with lamination layer 20. A solution
comprising a pressure sensitive adhesive or filled textured binder
is coated on to the other face of woven fabric 15, and the solvent
is removed via evaporation leaving layer 13.
[0078] The embodiment 24 of FIG. 5 shows a polyethylene or
polypropylene film 17, and a layer of pressure sensitive adhesive
13 on one face thereof. Cross-laminated films are preferred, such
as cross-laminated films commercially available from Van Leer under
the trademark VALERON. Other suitable cross-laminated films are
those manufactured by Interplas/Formosa.
[0079] Another embodiment of the invention (not shown) is an
organic or inorganic roofing felt coated with a pressure sensitive
adhesive or a filled textured binder. An organic roofing felt
comprises paper saturated with asphalt. An inorganic roofing felt
comprises a non-woven glass fabric saturated with asphalt.
[0080] FIG. 6 illustrates an embodiment 25 of a self-adhering
underlayment comprising a support layer 19, a pressure sensitive
adhesive layer or filled textured binder layer 13 on one major
surface thereof, and a second pressure sensitive adhesive 18 on the
opposite major surface thereof. The pressure sensitive layer 18 may
include rubber modified bitumen, and non-bituminous adhesives
comprising rubbers such as SIS, SBS, SEBS, SBR, natural rubber,
silicone, butyl rubber, isoprene, butadiene and acrylic rubber.
Preferably the layer 18 is used in a thickness of greater than or
equal to 5 mils, more preferably greater than or equal to 20
mils.
[0081] The support layer 19 comprises a film, a woven fabric, a
non-woven fabric, or a combination of these. Preferrably, the films
comprise a polyolefin, polyethylene, polypropylene, a polyester, or
a combination of these materials.
[0082] The non-skid underlayments of the present invention exhibit
a unique combination of valuable features in comparison to other
underlayments including: excellent skid resistance, yet are still
trafficable (the shoe soles of a pedestrian walking on the surface
of an underlayment of the present invention do not become stuck to
the underlayment), particularly when wet, lightweight, rollable,
and unrollable. For embodiments comprising a filled textured
binder, where the binder is a pressure sensitive adhesive or a
rubber, a unique combination of mechanisms act to impart a high
coefficient of friction, particularly when wet. Furthermore, for
embodiments comprising a filled textured binder the filler is
better adhered to the support sheet in comparison to the case for
other underlayments where the surface comprises a filler or
aggregate.
[0083] Skid resistance is demonstrated in example 2 below.
Underlayments of the present invention are lightweight in
comparison to other underlayments (and other roofing products)
comprising filler or aggregate on the surface because a low level
of filler is used and the particle size of the filler is small. It
was surprising to find that good skid resistance can be achieved
using a low level of small particle filler.
[0084] It was also surprising that a surface could be rendered skid
resistant with a pressure sensitive adhesive without compromising
the ability to unroll the membrane or walk on the membrane without
becoming stuck. For embodiments where the skid resistant layer
comprises only a pressure sensitive adhesive this is achieved by
use of a very thin layer of pressure sensitive adhesive. If a thick
layer of pressure sensitive adhesive were used as the non-skid
layer the underlayment would be impossible or difficult to unroll.
For example, for a 30'' wide membrane the minimum force required to
unroll the membrane comprising more than about 5 mils of pressure
sensitive adhesive or binder would be equal to or greater than 30
lbs. For embodiments comprising a filled textured binder, where the
binder is a pressure sensitive adhesive or rubber, (rubbers are
slightly tacky) excellent skid resistance, particularly when wet,
is achieved by the use of a thin non-skid layer that is textured
with a small particle size filler.
[0085] While not being bound by any specific theory, it is believed
that a single mechanism contributes to provide skid resistance for
embodiments comprising a pressure sensitive adhesive while two
possible mechanisms contribute to provide skid resistance for
embodiments comprising a filled textured binder where the binder is
a pressure sensitive adhesive or a rubber. For embodiments
comprising a pressure sensitive, adhesion of the non-skid coated
underlayment to the shoe sole of the walker provides for non skid
properties. For embodiments comprising a filled textured binder,
where the binder is a pressure sensitive adhesive or a rubber,
adhesion of the non-skid coated underlayment to the shoe sole of
the walker and mechanical interlock of the non-skid coated
underlayment to the shoe sole of the walker provide for non-skid
properties. For embodiments of the invention where the binder is a
resin it is believed that mechanical interlock substantially
provides for skid resistance. For resins, adhesion likely
contributes little to non-skid properties as resins are hard, low
tack materials by comparison with pressure sensitive adhesives and
rubbers. Embodiments of the invention comprising a filled textured
binder are textured as aforementioned as a result of the high
filler level and the filler is substantially coated with binder.
This is evident from the SEM photomicrographs of the top surfaces
of an underlayments coated with a filled textured binder in FIGS.
7A-7C.
[0086] The manufacturing method where a mixture of an organic
solvent, binder, and filler is coated onto a web comprising the
support layer, and the solvent is removed by evaporation, is
preferred because the filler is well bonded to the support sheet in
comparison to other manufacturing methods by virtue of being
substantially coated with binder. Other methods may be utilized to
coat a filled textured binder on to a support sheet. One option is
to coat a solution of the binder on to the support sheet, apply the
filler to the solution coated web, and remove the solvent by
evaporation. Yet another option is to coat the binder as a molten
layer on the support sheet, apply the filler while the binder is
still molten, and cool to solidify the binder. For these other
methods filler that is not well bonded to the support sheet acts as
a lubricant to enhance skidding instead of preventing skidding.
Other underlayments and other roofing products comprising an
aggregate or filler coated surface are made by the method involving
application of filler or aggregate to a molten surface. The molten
surface is most often asphalt.
[0087] There is another known technology for imparting skid
resistance to a trafficable surface. It involves coating with a
soft polymeric material, like that described above for layer 14.
These materials impart skid resistance by virtue of their softness.
Embodiments of the current invention are differentiated from such
materials compositionally and by the mechanism by which skid
resistance is imparted.
[0088] Other applications for the non-skid coating are
contemplated. The non-skid layers of the present invention may be
applied to plywood and oriented strand board. Use of these coated
decking materials enhances skid resistance particularly when these
materials are used on a sloped roof deck.
[0089] Another application is non-skid flexible packaging
materials. For example, plastic sacks may be coated with the
non-skid layers of the present invention to prevent sliding of
stacked arrays of products.
EXAMPLE 1
[0090] A blocking test was conducted, which is a severe test
designed to develop an understanding of blocking on a relative
basis. A control membrane, a polyolefin (PO) coated non-woven is
easily unrolled. The polyolefin coated control membrane comprises a
2 oz/yd non-woven polypropylene fabric coated on each side with
1.25 mils coex layer. On the side in contact with the
skid-resistant layer the coex layer comprise 1.0 mil layer PP/LDPE
blend and a 0.25 mils layer comprising a copolymer of ethylene and
methyl acrylate. The thin layer faces outward. The coex layer on
the other side of the non-woven comprises a 1 mil layer of a
PP/LDPE blend and a 0.25 mil layer comprising an ethylene/propylene
copolymer. The thin layer faces outward. If an experimental
membrane exhibits an ability to unroll as easily or more easily
versus the control in the accelerated test, than it is assumed that
the experimental membrane will unroll easier than the control under
normal circumstances.
[0091] The accelerated tests involve the application of high
pressure and high temperature. Two sheets of membrane are
positioned on top of the other with the surfaces to be tested in
contact with one another. The sheets are sandwiched between 2 steel
plates. The assembly is loaded in a heated press to 250 psi at
75.degree. C. for 16 hrs. The force required to peel the sheets
apart is then measured with a mechanical test device such as an
Instron. The peel rate is 2''/min. A T-Peel test geometry is used.
Results are shown in the five Tables below. In the Tables, "SIS" is
a styrene/butadiene/styrene block copolymer, "PO" is polyolefin,
"PP" is polypropylene, "HDPE" is high density polyethylene, "SEBS"
is styrene/ethylene/butylenes/styrene block copolymer, and "PSA"
indicates a pressure sensitive adhesive.
[0092] In FIGS. 11-13, peel force, a measure of blocking, is
plotted versus the pressure sensitive adhesive coating thickness.
An SIS, acrylic, and an SEBS pressure sensitive adhesive were
evaluated by coating on different membranes including a polyolefin
coated non-woven (described above), a membrane that comprises a 2
oz/yd polypropylene woven fabric laminated to a 1 mil
polypropylene/ethylene vinyl acetate wherein the ethylene vinyl
acetate layer faces outward coextruded film with 1 mil of a
polypropylene/polyethylene mixture, and an HDPE film which is 3 mil
Valeron.
[0093] With the exception of the acrylic coated HDPE film, all
pressure sensitive adhesive coated webs exhibited a lower
resistance to blocking versus the control (FIGS. 11 to 13).
[0094] Blocking was also evaluated for membranes coated with a
filled textured acrylic pressure sensitive adhesive and the results
are shown in FIG. 14. The filled coating comprises 75 percent, by
weight, of a 325 mesh calcium carbonate. The volume of the coating
on each membrane was .about.0.93 cc/ft2 (weight=16 g/yd2). All
membranes coated with the filled pressure sensitive adhesive
exhibit lower resistance to blocking versus the control.
[0095] Blocking was also evaluated for membranes coated with a
filled textured SEBS pressure sensitive. The filler is 325 mesh
calcium carbonate. The effects of coating volume and membrane type
were evaluated. Coating volume was varied between about 1 cc/ft2 to
15 cc/ft2. Two membranes were evaluated. One comprises the
polyolefin coated non-woven as described above. The other comprises
the polypropylene woven as described above. The results are given
in FIG. 15. Note that the level of blocking is proportional to the
coating volume. The peel force is less than 0.5 pli for coating
volumes less than about 10 cc/ft2.
[0096] Blocking was also evaluated for membranes coated with a
filled textured SEBS pressure sensitive adhesive and the results
are shown in FIG. 16. The effects of filler volume percent and the
effects of coating volume on blocking were evaluated. The filler
was a 325 mesh calcium carbonate. Blocking is lowest for
underlayments comprising a low coating volume and a high percent by
volume of filler. For the underlayment comprising a coating with 27
percent filler by volume and 10.3 cc/ft2 of coating blocking is
severe.
EXAMPLE 2
[0097] Skid resistance was measured in a "walk on" test as follows.
Underlayment specimens to be tested were mechanically attached to a
sheet of plywood and positioned at a test angle of 40.degree.. The
samples were sprayed with water prior to testing. A tester
("walker") walks over the sample and compares the wet skid
resistance of the sample to a "control", which was a membrane
comprising a 2 side polyolefin-coated polypropylene non-woven
described above. The "walker" judges the sample membrane to exhibit
better, similar or worse skid resistance versus the control
membrane. The results for various underlayments tested are shown in
Table 1. Samples 1-13 are embodiments of the present invention and
all exhibit superior wet skid resistance in comparison to the
control membrane. It's also important to note that water-based
binders comprising a surfactant impart poor wet skid resistance.
See test results for specimens 25 to 27 in Table 1 where all of the
non-skid layers are acrylic emulsions commercially available from
Rohm and Haas company. In the "walk on" test, these binders have
poor wet adhesion to the support sheet which contributes to poor
wet skid resistance. It is believed that the surfactant also lowers
the surface tension of water on the wet surface which contributes
to poor wet skid resistance. TABLE-US-00001 TABLE 1 Wet Skid No.
Support Layer Non-Skid Layer Resistance 1 2 side polyolefin coated
non-woven polypropylene.sup.1 5 u SIS PSA Better 2 2 side
polyolefin coated non-woven polypropylene.sup.1 5 u SEBS PSA Better
3 2 side polyolefin coated non-woven polypropylene.sup.1 5 u
Acrylic PSA Better 4 Woven polypropylene-polypropylene film
laminate.sup.2 5 u SIS PSA Better 5 Woven
polypropylene-polypropylene film laminate.sup.2 5 u SEBS PSA Better
6 Woven polypropylene-polypropylene film laminate.sup.2 5 u Acrylic
PSA Better 7 2 side polyolefin coated non-woven polypropylene.sup.1
1 cc/ft2 - 325 mesh CaCO3/SIS PSA (53% by Better volume CaCO3) 8 2
side polyolefin coated non-woven polypropylene.sup.1 1 cc/ft2 - 325
mesh CaCO3/SEBS PSA (53% by Better volume CaCO3) 9 2 side
polyolefin coated non-woven polypropylene.sup.1 1 cc/ft2 - 325 mesh
CaCO3/acrylic PSA (53% by Better volume CaCO3) 10 Woven
polypropylene-polypropylene film laminate.sup.2 1 cc/ft2 - 325 mesh
CaCO3/SIS PSA (53% by Better volume CaCO3) 11 Woven
polypropylene-polypropylene film laminate.sup.2 1 cc/ft2 - 325 mesh
CaCO3/SEBS PSA (53% by Better volume CaCO3) 12 Woven
polypropylene-polypropylene film laminate.sup.2 1 cc/ft2 - 325 mesh
CaCO3/acrylic PSA (53% by Better volume CaCO3) 13 2 side polyolefin
coated non-woven polypropylene.sup.1 2 cc/ft2 - Portland
Cement/amorphous polyolefin Better (Eastoflex P1010-Eastman) (53%
by volume Portland Cement) 14 Woven polypropylene-polypropylene
film laminate.sup.2 1 cc/ft2 - 325 mesh CaCO3/butyl rubber (53% by
Better volume CaCO3) 15 Woven polypropylene-polypropylene film
laminate.sup.2 1 cc/ft2 - 325 mesh CaCO3/chloroprene rubber Better
(53% by volume CaCO3) 16 2 side polyolefin coated non-woven
polypropylene.sup.1 none NA (control) 17 Woven
polypropylene-polypropylene film laminate none Same 18 2 side
polyolefin coated non-woven polypropylene.sup.1 1 oz/yd2 hot melt
spray applied amorphous Same polyolefin (Eastoflex P1010-Eastman)
19 Woven polypropylene-polypropylene film laminate.sup.2 1 oz/yd2
hot melt spray applied amorphous Same polyolefin (Eastoflex
P1010-Eastman) 20 EPDM Rubber Sheet none Same 21 2 side polyolefin
coated non-woven polypropylene.sup.1 2 to 3 oz/yd2 embossed low
molecular weight Same polyethylene/tackifier blend (70/30 by
weight) 22 Woven polypropylene-polypropylene film laminate.sup.2 2
to 3 oz/yd2 embossed low molecular weight Same
polyethylene/tackifier blend (70/30 by weight) 23 Web comprising
HPDE woven fabric and polyolefin grid polyolefin coated polyolefin
grid with nodes Same with nodes.sup.3 24 Web comprising
spunbonded/thermobonded spunbonded/thermobonded polypropylene non-
Worse polypropylene non-woven fabric surface.sup.4 woven fabric
surface 25 Woven polypropylene-polypropylene film laminate.sup.2 4
cc/ft2 - CaCO3/dry Acronal S400 (53% by Worse volume CaCO3) 26
Woven polypropylene-polypropylene film laminate.sup.2 2.8 cc/ft2 -
CaCO3/dry Acronal A3234 (53% by Worse volume CaCO3) 27 Woven
polypropylene-polypropylene film laminate.sup.2 4.1 cc/ft2 -
CaCO3/dry Acronal V275 (53% by Worse volume CaCO3) Acronal S400
acrylic emulsion 2.3 Acronal A3234 acrylic emulsion 1.2 Acronal
V275 acrylic emulsion 1.9 .sup.1-2oz/yd non-woven polypropylene
fabric coated on each side with 1.25 mils coex layer. On the side
in contact with the skid-resistant layer the coex layer comprise
1.0 mil layer PP/LDPE blend and a 0.25 mils # layer comprising a
copolymer of ethylene and methyl acrylate. The coex layer on the
other side of the non-woven comprises a 1 mil layer of a PP/LDPE
blend and a .25 mil mayer comprising an ethylene/propylene
copolymer
EXAMPLE 3
[0098] Adhesion of the non-skid coating to the support sheet is
measured in a peel adhesion test using a pre-formed pressure
sensitive tape. A 2'' wide preformed tape, "Preprufe.RTM. Tape", is
applied to the non-skid coated face of the underlayment. The sample
is rolled 4 times, at 1 second per pass, with a 30 lb roller.
Adhesion is measured in a T-peel adhesion test 15 min after rolling
at a cross head speed of 2'' per minute with an Instron mechanical
tester. Results for various underlayments comprising a woven
polypropylene mesh coated with a filled textured binder are shown
in Table 2. Note that all underlayments, except for that comprising
gilsonite, passes the minimum adhesion requirement for an
underlayment comprising a filled textured binder. Also note that
the 3 underlayments comprising the acrylic emulsion binders in the
non-skid layer also pass the minimum adhesion requirement. However,
these underlayments exhibit poor wet skid resistance as noted in
example 2 because these binders are water-based and comprise a
surfactant. These binders have poor wet adhesion to the support
sheet. It is believed that the surfactant also lowers the surface
tension of water on the wet surface which contributes to poor wet
skid resistance. TABLE-US-00002 TABLE 2 Avg. Coating Load Volume
Binder Trade Name Binder Type* (pli) (cc/ft2) Elastotac H130
hydrocarbon resin 1.9 2.0 Gilsonite 0.1 3.3 Neoprene Chloroprene
rubber 1.9 1.0 Butyl rubber 3.4 0.9 Acronal S400 acrylic emulsion
2.3 4.0 Acronal A3234 acrylic emulsion 1.2 2.8 Acronal V275 acrylic
emulsion 1.9 4.1 SEBS PSA 3.3 1.6 *53 percent filler, CaCO3, by
volume for all formulations
EXAMPLE 4
[0099] For embodiments comprising a filled textured binder
texturing may be observed via scanning electron microscopy SEM. SEM
photomicrographs were recorded for a membranes comprising a woven
polypropylene support sheet coated with binders comprising an SEBS
adhesive filled with CaCO3. The volume fraction of filler was
varied between 53 percent and 27 percent by volume. See FIGS. 7A,
7B, and & 7C for non-skid coatings comprising 53 percent, 38
percent, and 27 percent, respectively. Note that texturing may be
observed even down to 27 percent by volume of filler.
* * * * *