U.S. patent application number 11/472076 was filed with the patent office on 2006-10-26 for polymeric foam and scrim sheathings.
This patent application is currently assigned to PACTIV CORPORATION. Invention is credited to Kenneth Franklin, John W. II Lubker, Douglas S. Nordgren.
Application Number | 20060236641 11/472076 |
Document ID | / |
Family ID | 32871719 |
Filed Date | 2006-10-26 |
United States Patent
Application |
20060236641 |
Kind Code |
A1 |
Nordgren; Douglas S. ; et
al. |
October 26, 2006 |
Polymeric foam and scrim sheathings
Abstract
A sheathing adapted to be fastened to at least one wall
supporting structure comprises at least two layers. The first layer
comprises a polymeric foam layer. The second layer comprises a
polymeric scrim and is located adjacent to the first layer. The
second layer has a first portion and a second portion. The second
portion is located near the periphery of the polymeric scrim layer.
The first portion has a first machine direction (MD) scrim count
number and a first transverse direction (TD) scrim count number,
and the second portion has a second MD scrim count number and a
second TD scrim count number. At least one of the second MD scrim
count number and the second TD scrim count number is greater than
the respective first MD scrim count number or the first TD scrim
count number so as to inhibit failure of the scrim.
Inventors: |
Nordgren; Douglas S.;
(Winchester, VA) ; Lubker; John W. II; (Roswell,
GA) ; Franklin; Kenneth; (Fayeteville, GA) |
Correspondence
Address: |
JENKENS & GILCHRIST, P.C.
225 WEST WASHINGTON
SUITE 2600
CHICAGO
IL
60606
US
|
Assignee: |
PACTIV CORPORATION
|
Family ID: |
32871719 |
Appl. No.: |
11/472076 |
Filed: |
June 21, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10782480 |
Feb 19, 2004 |
7093397 |
|
|
11472076 |
Jun 21, 2006 |
|
|
|
09660649 |
Sep 13, 2000 |
7100337 |
|
|
10782480 |
Feb 19, 2004 |
|
|
|
09421031 |
Oct 20, 1999 |
6536176 |
|
|
09660649 |
Sep 13, 2000 |
|
|
|
Current U.S.
Class: |
52/506.1 |
Current CPC
Class: |
B32B 5/24 20130101; B32B
37/1284 20130101; B32B 5/18 20130101; B32B 27/065 20130101; B32B
27/302 20130101; E04B 2/707 20130101; B32B 7/12 20130101; B32B
27/32 20130101; B32B 38/145 20130101; B32B 38/105 20130101; B32B
2419/00 20130101; B32B 2266/025 20130101; E04F 13/18 20130101; B32B
2266/0264 20130101; B32B 2307/712 20130101; B32B 2307/546 20130101;
E04F 13/0864 20130101; B32B 2305/022 20130101; B32B 2323/10
20130101; E04B 1/80 20130101; B32B 27/08 20130101; B32B 2459/00
20130101; B32B 37/12 20130101 |
Class at
Publication: |
052/506.1 |
International
Class: |
E04B 9/00 20060101
E04B009/00 |
Claims
1. A sheathing adapted to be fastened to at least one wall
supporting structure, comprising at least two layers: (a) a first
layer comprising a polymeric foam layer; (b) a second layer
comprising a woven polymeric scrim, said second layer being located
adjacent to said first layer, wherein the polymeric scrim includes
a first portion and a second portion, the second portion being
located near the periphery of the polymeric scrim layer, the first
portion having a first machine direction scrim count number and a
first transverse direction scrim count number, the second portion
having a second machine direction scrim count number and a second
transverse direction scrim count number, at least one of the second
machine direction scrim count number and the second transverse
direction scrim count number being greater than the respective
first machine direction scrim count number or the first transverse
direction scrim count number; (c) an adhesive located between said
first and said second layers; and (d) a third layer comprising an
impact polystyrene, said first layer being located between the
adhesive and said third layer.
2. The sheathing of claim 1, wherein the polymeric scrim includes a
third portion, the third portion being located near the periphery
of the polymeric scrim layer opposite the second portion, the third
portion having a third machine direction scrim count number and a
third transverse direction scrim count number, at least one of the
third machine direction scrim count number and the third transverse
direction scrim count number being greater than the respective
first machine direction scrim count number or the first transverse
direction scrim count number.
3. The sheathing of claim 2, wherein the second and third machine
direction scrim count numbers are the same.
4. The sheathing of claim 2, wherein the second and third
transverse direction scrim count numbers are the same.
5. The sheathing of claim 2, wherein the second and third portions
are located generally parallel to the at least one wall supporting
structure.
6. The sheathing of claim 2, wherein the second and third machine
direction scrim count numbers are the same and the second and third
transverse direction scrim count numbers are the same.
7. The sheathing of claim 1, wherein the second machine direction
scrim count number is at least about two times the first machine
direction scrim count number.
8. The sheathing of claim 2, wherein the second and third machine
direction scrim count numbers are at least about two times the
first machine direction scrim count number.
9. The sheathing of claim 1, wherein the second machine direction
scrim count number is at least about four times the first machine
direction scrim count number.
10. The sheathing of claim 2, wherein the second and third machine
direction scrim count numbers are at least about four times the
first machine direction scrim count number.
11. The sheathing of claim 1, wherein the second machine direction
scrim count number is at least about six times the first machine
direction scrim count number.
12. The sheathing of claim 2, wherein the second and third machine
direction scrim count numbers are at least about six times the
first machine direction scrim count number.
13. The sheathing of claim 1, wherein the thickness of the
sheathing is from about 0.25 inch to about 3 inches.
14. The sheathing of claim 2, wherein the second and third portions
extend from the periphery of the polymeric scrim layer inwardly
about 2 to about 3 inches.
15. The sheathing of claim 1, wherein the first layer is a
polyethylene terephthalate foam.
16. The sheathing of claim 1 further including a fourth layer
comprising an impact polystyrene, said fourth layer being located
adjacent to said first layer and said first layer being located
between said third and said fourth layers.
17. The sheathing of claim 16 further including a polymeric film
layer, said third layer located between said first layer and said
polymeric film layer.
18. The sheathing of claim 1, wherein said impact polystyrene is a
high impact polystyrene.
19. The sheathing of claim 1 further including a polymeric film
layer, said third layer located between said first layer and said
polymeric film layer.
20. The sheathing of claim 1, wherein said polymeric foam is a
polyolefin foam.
21. The sheathing of claim 1 wherein said polymeric foam is a
polystyrenic foam.
22. The sheathing of claim 1, wherein said polymeric scrim is a
polypropylene scrim.
23. The sheathing of claim 1, wherein said polymeric scrim is a
polyolefin scrim.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of U.S. patent
application Ser. No. 10/782,480, filed on Feb. 19, 2004, which is a
continuation of U.S. patent application Ser. No. 09/660,649, filed
on Sep. 13, 2000, which is a Continuation-in-Part of U.S. patent
application Ser. No. 09/421,031, filed on Oct. 20, 1999, now U.S.
Pat. No. 6,536,176 B1. These related applications are hereby
incorporated by reference in their entirety.
FIELD OF THE INVENTION
[0002] The present invention relates generally to sheathings that
are used in structures and, more particularly, to polymeric foam
sheathing materials that are used in prefabricated housing, site
built housing, and remodeling.
BACKGROUND OF THE INVENTION
[0003] There are different commercial sheathings that are used in
the construction of buildings. Sheathings include materials that
span the frame supports of buildings. Some of the commercial
products that have been used as sheathing include thin composite
laminations, fiberboard, orientated strand board (OSB) and plywood.
Some of these products provide structural strength, durability
and/or rigidity. These products, however, have disadvantages such
as being heavy and difficult to install, providing little
insulation and/or having poor moisture resistance.
[0004] There are other commercial products that are available as
sheathing. For example, polyisocyanurate foam, extruded polystyrene
foam, and molded expanded polystyrene (EPS) foam. These existing
foamed materials generally have advantages such as increased
insulation and easier handling. These existing foamed materials,
however, have disadvantages such as their lack of strength as
measured by wind resistance. This is shown, for example, by their
failures to withstand 100 miles per hour winds when installed. Lack
of wind resistance may cause problems such as fracturing, cracking
and/or edge pull out of the sheathing from the fasteners. During
the pulling of the edge of the material, the fastener generally
remains, but the sheathing is pulled away.
[0005] Existing foam sheathing is still susceptible to damage at
the building site prior to installation. This problem is further
evident when, for example, delays occur in the installation and/or
the installation occurs in extreme weather conditions. One common
example of damage that may occur is when a piece breaks off from a
remainder of the sheathing during the process of installation or by
vandalism after installation at the building site before being
covered with an exterior facing such as siding, brick, or
stucco.
[0006] Accordingly, a need exists for a sheathing material for use
in prefabricated housing, site built housing, and remodeling that
overcomes the above-noted shortcomings associated with existing
sheathing.
SUMMARY OF THE INVENTION
[0007] According to one embodiment of the present invention, a
sheathing adapted to be fastened to at least one wall supporting
structure comprises at least two layers. The first layer comprises
a polymeric foam layer. The second layer comprises a polymeric
scrim and is located adjacent to the first layer. The second layer
has a first scrim portion and a second portion. The second portion
is located near the periphery of the polymeric scrim layer. The
first portion has a first machine direction (MD) scrim count number
and a first transverse direction (TD) scrim count number, and the
second portion has a second MD scrim count number and a second TD
scrim count number. At least one of the second MD scrim count
number and the second TD scrim count number is greater than the
respective first MD scrim count number or the first TD scrim count
number so as to inhibit failure of the scrim.
[0008] According to another embodiment, a sheathing adapted to be
fastened to at least one wall supporting structure comprises at
least two layers. The first layer comprises a polymeric foam layer
and is located adjacent the second layer. The second layer
comprises a polymeric scrim having a uniform scrim count number.
The polymeric scrim has a machine direction (MD) scrim count number
which is least 18 and a transverse direction (TD) scrim count
number which is at least 4 so as to inhibit failure of the
scrim.
[0009] According to another embodiment of the present invention, a
sheathing adapted to be fastened to at least one wall supporting
structure comprises at least three layers. The first layer
comprises a polymeric foam layer. The second layer comprises a
polymeric scrim and has a first portion and a second portion. The
second portion is located near the periphery of the polymeric scrim
layer. The first portion has a first machine direction (MD) scrim
count number and a first transverse direction (TD) scrim count
number, and the second portion has a second MD scrim count number
and a second TD scrim count number. At least one of the second MD
scrim count number and the second TD scrim count number is greater
than the respective first MD scrim count number or the first TD
scrim count number so as to inhibit failure of the scrim. The third
layer comprises an impact polystyrene and is located between the
first and the second layers.
[0010] According to one method of the present invention, a
sheathing is provided that comprises at least two layers. The first
layer comprises a polymeric foam layer. The second layer comprises
a polymeric scrim and is located adjacent to the first layer. The
second layer has a first portion and a second portion. The second
portion is located near the periphery of the polymeric scrim layer.
The first portion has a first machine direction (MD) scrim count
number and a first transverse direction (TD) scrim count number,
and the second portion has a second MD scrim count number and a
second TD scrim count number. At least one of the second MD scrim
count number and the second TD scrim count number is greater than
the respective first MD scrim count number or the first TD scrim
count number so as to inhibit failure of the scrim. The sheathing
is installed to a wall supporting structure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 shows a side view of a two-layer sheathing according
to one embodiment of the present invention.
[0012] FIGS. 2a and 2b show front views of the second layer of the
sheathing according to two embodiments of the present
invention.
[0013] FIG. 3 shows a side view of a three-layer sheathing
according to another embodiment of the present invention.
[0014] FIG. 4 shows a side view of a four-layer sheathing according
to another embodiment of the present invention.
[0015] FIG. 5 shows a side view of a five-layer sheathing according
to yet another embodiment of the present invention.
[0016] FIG. 6 shows a side view of a seven-layer sheathing
according to a further embodiment of the present invention.
[0017] FIG. 7 shows a cut-away perspective view of a five-layer
sheathing fastened to a wall supporting structure according to one
embodiment of the present invention using the second layer
embodiment depicted in FIG. 2a.
[0018] FIG. 8 shows a schematic flow diagram of an overall sequence
of operations according to one process involved in the manufacture
of a three-layer sheathing such as that shown in FIG. 3.
[0019] While the invention is susceptible to various modifications
and alternative forms, specific embodiments thereof have been shown
by way of example in the drawings and will herein be described in
detail. It should be understood, however, that it is not intended
to limit the invention to the particular forms disclosed but, on
the contrary, the intention is to cover all modifications,
equivalents, and alternatives falling within the spirit and scope
of the invention as defined by the appended claims.
DESCRIPTION OF SPECIFIC EMBODIMENTS
[0020] Turning now to the drawings and referring initially to FIG.
1, a two-layer sheathing 10 is shown according to one embodiment of
the present invention. The sheathings of the present invention,
including sheathing 10, are adapted to be fastened to a wall
supporting structure. On a building, sheathings are typically
covered by an exterior facing such as siding, brick or stucco. The
sheathing 10 of FIG. 1 comprises a polymeric scrim layer 12 and a
polymeric foam layer 14. The polymeric scrim layer 12 of the
present invention provides additional strength and durability to
the polymeric foam layer 14. Polymeric Scrim Layer The polymeric
scrim layer 12 may be made of woven material or non-woven material.
Woven material is generally defined as long fibers that are
intertwined to produce a material. Non-woven material is generally
defined as randomly joined fibers that are bonded or pressed
together by adhesive or other means. The randomly joined fibers
that form non-woven material are typically shorter than those used
in forming woven material. The woven material is generally
preferred because it provides an excellent strength to weight ratio
that is desirable in wind-resistant applications.
[0021] One type of woven scrim that may be used in polymeric scrim
layer 12 is a scrim that runs in the machine direction (MD) and the
weft or transverse direction (TD). For example, a scrim having a
scrim count of 28.times.4 indicates that the scrim has 28 cords,
filaments, or strands per inch in the machine direction and 4
cords, filaments, or strands per inch in the transverse direction.
A scrim having cords that run in the machine direction and the weft
or transverse direction is commonly referred to as a cross-woven
scrim. This type of woven scrim may be the type that is commonly
used in applications such as carpet backing.
[0022] FIGS. 2a and 2b depict embodiments of respective polymeric
scrim layers 112, 212 according to the present invention. As
depicted in FIG. 2a, the polymeric scrim layer 112 has a first
portion 102 and a second portion 104. The first portion 102 is
located in the central area of the polymeric scrim layer 112 while
the second portion 104 is located near the periphery of the
polymeric scrim layer 112. The second portion 104 extends from the
periphery of the polymeric scrim layer 112 inwardly toward the
central portion of the polymeric scrim layer 112.
[0023] The first portion 102 has a first machine direction (MD)
scrim count number running in the machine direction 108 and a first
transverse direction (TD) scrim count number running in the
transverse direction 110. Similarly, the second portion 104 has a
second MD scrim count number running in the machine direction 108
and a second TD scrim count number running in the transverse
direction 110. At least one of the second MD scrim count number and
the second TD scrim count number is greater than the respective
first MD scrim count number or the first TD scrim count number. By
increasing the scrim count at the periphery of the polymeric scrim
layer 112, the periphery of the polymeric scrim layer 112 is
reinforced and inhibits the scrim from unraveling.
[0024] As depicted in FIG. 2a, the polymeric scrim layer 112 may
also include a third portion 106. The third portion 106 is located
near the periphery of the polymeric scrim layer 112 opposite the
second portion 104. The third portion 106 extends from the
periphery of the polymeric scrim layer 112 inwardly toward the
central portion of the polymeric scrim layer 112. The third portion
106 has a third MD scrim count number running in the machine
direction 108 and a third TD scrim count number running in the
transverse direction 110. At least one of the third MD scrim count
number and the third TD scrim count number is greater than the
respective first MD scrim count number or the first TD scrim count
number. Optionally, the second and third MD scrim count numbers are
the same, and the second and third TD scrim count numbers are the
same.
[0025] As depicted in FIGS. 2a and 2b, the second and third MD
scrim count numbers vary. The MD scrim count number, however, can
be varied based upon the desired use of the sheathing and the cost.
FIG. 2a depicts an embodiment where the second MD scrim count
number is the same at the third MD scrim count number and the
second and third MD scrim count numbers are at least two times the
first MD scrim count number. The second and third MD scrim count
numbers can range from at least two times, at least four times, and
to at least six times the first MD scrim count number.
[0026] FIG. 2b depicts another embodiment of the polymeric scrim
layer 212 according to the present invention. Polymeric scrim layer
212 has a first portion 202, a second portion 204 and a third
portion 206. The first portion 202 is located in the central area
of the polymeric scrim layer 212. The second and third portions
204, 206 are located near the periphery of the polymeric scrim
layer 212 on opposing sides. The first portion 202 has a first MD
scrim count number in the machine direction 208 and a first TD
scrim count number in the transverse direction 210. The second
portion 204 has a second MD scrim count number in the machine
direction 208 and a second TD scrim count number in the transverse
direction 210. The third portion 206 has a third MD scrim count
number in the machine direction 208 and a third TD scrim count
number in the transverse direction 210. FIG. 2b depicts an
embodiment where the second and third MD scrim count numbers are
the same and the second and third MD scrim count numbers are at
least six times the first MD scrim count number.
[0027] The distance that the second and third portions extend from
the periphery of the polymeric scrim layer 112, 212 varies. The
second and third portions generally extend from the periphery of
the polymeric scrim layer 112, 212 about 1/2 of an inch to about 3
inches. The second and third portions preferably extend from the
periphery of the polymeric scrim layer 112, 212 about 1/2 of an
inch to about 1 inch.
[0028] The second portion 104, 204 is preferably located on at
least two opposing portions of the periphery of the polymeric scrim
layer 112, 212. It is preferred that the second portion extends
along two entire sides of the polymeric scrim layer 112, 212. It is
also contemplated that the third portion 106, 206 may be located on
one or more of the sides of the polymeric scrim layer 112, 212
rather than the second portion 104, 204. The second and third
portions are located generally parallel to the wall supporting
structure.
[0029] It is contemplated that various scrim counts may be used in
forming the polymeric scrim layer having an increased scrim count
at the periphery. Examples of suitable scrim counts that may be
used in the central portion of the polymeric scrim layer having an
increased scrim count at the periphery include 7.times.4,
8.times.6, 9.times.4, 21.times.4, 24.times.4, 28.times.4,
18.times.6, and 21.times.6. It is contemplated that the scrim count
number at the periphery of the polymeric layer will be greater than
the scrim count number in the central portion and that the
selection of the scrim count number at the periphery will vary
based on the desired use of the sheathing and the cost.
[0030] According to another embodiment, the polymeric scrim layer
has a uniform scrim count number so as to inhibit failure of the
scrim. According to this embodiment, the polymeric scrim layer has
an MD scrim count number which is least 18 and a TD scrim count
number which is at least 4. Examples of suitable scrim counts that
may be used where the polymeric scrim layer has a uniform scrim
count number include 21.times.4, 24.times.4, 28.times.4,
18.times.6, and 21.times.6.
[0031] The polymeric scrim layer 12 may be made of materials such
as polyolefins, polyesters and nylons. Polyolefins that may be used
in the polymeric scrim layer 12 include polypropylenes or
polyethylenes. The term "polypropylene" as used herein includes
polymers of propylene or polymerizing propylene with other
aliphatic polyolefins, such as ethylene, 1-butene, 1-pentene,
3-methyl-1-butene, 4-methyl-1-pentene, 4-methyl-1-hexene,
5-methyl-1-hexene and mixtures thereof. Polypropylene not only
includes homopolymers of propylene, but also propylene copolymers
comprised of at least 50 mole percent (preferably at least 70 mole
percent) of a propylene unit and a minor proportion of a monomer
copolymerizable with propylene and blends of at least 50 percent by
weight of the propylene homopolymer with another polymer.
[0032] The term "polyethylene" as used herein includes low density
polyethylene (LDPE), medium density polyethylene (MDPE), high
density polyethylene (HDPE), very low density polyethylene (VLDPE),
linear low density polyethylene (LLDPE), metallocene-catalyzed
linear low density polyethylene (mLLDPE) and combinations
thereof.
[0033] LDPE is generally defined as an ethylenic polymer having a
specific gravity of from about 910 to about 925 kg/m.sup.3. MDPE is
generally defined as an ethylenic polymer having a specific gravity
between the LDPEs and the HDPEs (i.e., from about 925 to about 940
kg/m.sup.3). The high density polyethylene (HDPE) of the present
invention has a specific gravity of from about 940 to about 970
kg/m.sup.3. The term polyethylene as used herein includes
homopolymers of ethylene and copolymers comprised of at least 50
mole percent of a ethylene unit (preferably at least 70 mole
percent) and a minor (i.e., less than 50%) proportion of a monomer
copolymerizable with the ethylene unit. The term LDPE as used
herein also includes physical blends of two or more different
homopolymers that are classified as LDPEs. Similarly, the term MDPE
and HDPE may also include blends of two or more different
homopolymers classified as MDPEs and HDPEs, respectively.
[0034] The VLDPE resins have densities ranging from about 880 to
about 912 kg/m.sup.3, more commonly from about 890 to about 910
kg/m.sup.3, and melt indices of from about 0.5 to about 5 g/10
min., and from about 1 to about 3 g/10 min.
[0035] The LLDPE of the present invention generally has from about
1 to about 20, preferably from about 1 to about 10 weight percent
of said higher alpha olefin monomer copolymerized therein. In
addition, the alpha olefin monomer employed in the ethylenic
copolymer may be selected from the group consisting of 1-butene,
3-methyl-1-butene, 3 methyl-1-pentene, 1-hexene,
4-methyl-1-pentene, 3-methyl-1-hexene, 1-octene and 1-decene. The
LLDPE resins that may be used in the present invention have
densities ranging from about 890 to about 940 kg/m.sup.3, more
commonly from about 900 to about 930 kg/m.sup.3, and a melt index
(I.sub.2) of from about 1 to about 10 g/10 min. as determined by
ASTM D1238.
[0036] The metallocene-catalyzed polyethylene (mLLDPE) is a polymer
having a low polydispersity. The low polydispersity polymer may be
prepared from a partially crystalline polyethylene resin that is a
polymer prepared with ethylene and at least one alpha olefin
monomer, e.g., a copolymer or terpolymer. The alpha olefin monomer
generally has from about 3 to about 12 carbon atoms, preferably
from about 4 to about 10 carbon atoms, and more preferably from
about 6 to about 8 carbon atoms. The alpha olefin comonomer content
is generally below about 30 weight percent, preferably below about
20 weight percent, and more preferably from about 1 to about 15
weight percent. Exemplary comonomers include propylene, 1-butene,
1-pentene, 1-hexene, 3-methyl-l-pentene, 4-methyl-1-pentene,
1-octene, 1-decene, and 1-dodecene.
[0037] The low polydispersity polymer has a density of from about
880 to about 940 kg/m.sup.3. The polydispersity polymer generally
have a molecular weight distribution, or polydispersity,
(M.sub.w/M.sub.n, "MWD") within the range of from about 1 to about
4, and more typically from about 2 to about 3. The melt flow ratio
(MFR) of these polymers, defined as I.sub.20/I.sub.2 and as
determined in accordance to ASTM D1238, is generally from about 12
to about 22 and typically from about 14 to about 20. The melt index
(MI), defined as the I.sub.2 value, should be in the range of from
about 0.5 to about 10 g/10 min. and typically from about 1 to about
5 g/10 min. as determined by ASTM D1238.
[0038] An example of a "polyester" includes a polyester resin which
is a polycondensation product of a dicarboxylic acid with a
dihydroxy alcohol. An example of a "polyethylene terephthalate"
includes a polyester resin made from ethylene glycol and
terephthalic acid. An example of a "nylon" is a polyamide polymer
that is characterized by the presence of the amide group
(--CONH).
[0039] It is contemplated that additional polymeric scrim layer(s)
can be added to the sheathing. For example, the sheathing may
include polymeric scrim layers on opposing sides of the polymeric
foam layer.
Polymeric Foam Layer
[0040] The polymeric foam layer 14 is located adjacent to the scrim
layer 12 in FIG. 1. The polymeric foam layer 14 may be made from
alkenyl aromatic resins, such as polystyrenic resin(s), and
polyesters such as polyethylene terephthalates. The term "alkenyl
aromatic polymer" as used herein includes polymers of aromatic
hydrocarbon molecules that contain an aryl group joined to an
olefinic group with only double bonds in the linear structure. The
polymeric foam layer 14 may also be made from polyolefinic resins
such as LDPEs, HDPEs, LLDPEs, and the like. The polymeric foam
layer 14 is preferably made from a polystyrenic resin(s), such as a
general purpose polystyrene, because of economical considerations
at the present time. The polymeric foam layer 14, however, may be
made from other polystyrenic resins such as impact polystyrenes.
The impact polystyrenes that are generally used include medium
impact polystyrenes and high impact polystyrenes. The polymeric
foam layer 14 may also be made from a combination of virgin and/or
reprocessed material. The polymeric foam layer 14, however, may
also be made from polyisocyanurate foam.
[0041] The polymeric foam layer 14 and the polymeric scrim layer 12
may be bonded by attaching, adhering, fusing or the like. For
example, the polymeric foam layer 14 and the polymeric scrim layer
12 may be thermally bonded to each another depending on the
selected materials for forming the layers 12 and 14. Thermal
bonding may be accomplished by conventional methods, such as a
flameless air torches, heated rolls, radiant heaters and infrared
heating.
Adhesive and Other Layers
[0042] Alternatively, the polymeric foam layer 14 and the polymeric
scrim layer 12 may be attached with an adhesive layer. This is
shown in FIG. 3 where sheathing 30 includes a polymeric scrim layer
12, a polymeric foam layer 14 and an adhesive layer 16. The
optional adhesive layer 16 is located between the polymeric scrim
layer 12 and the polymeric foam layer 14. One type of adhesive that
may be used is ethylene vinyl acetate (EVA). For example, modified
EVAs such as BYNEL.RTM. made by DuPONT(.RTM. or Plexar.RTM. made by
Equistar Chemicals may be used. These modified EVAs have melt
indices generally from about 6.4 to about 25 g/10 min. as measured
by ASTM D1238and densities generally from about 923 to about 947
kg/m.sup.3 as measured by ASTM D1505. BYNEL.RTM. is an adhesive
that is designed to bond materials that would not ordinarily adhere
to each other.
[0043] Other adhesives that may be used include block copolymers
that comprise polymeric regions of styrene-rubber-styrene. For
example, KRATON.RTM. made by Shell(.RTM. Chemical Company may be
used. Other adhesives are contemplated in the present invention to
bond the polymeric scrim layer 12 to the polymeric foam layer
14.
[0044] Additional layers are contemplated in the sheathings of the
present invention. For example, FIGS. 4, 5 and 6 depict a
four-layer sheathing, a five-layer sheathing and a seven-layer
sheathing, respectively. Referring specifically to FIG. 4,
sheathing 40 includes a polymeric scrim layer 12, a polymeric foam
layer 14, an adhesive layer 16 and an impact polystyrenic layer 18.
The polystyrenic layer 18 is preferably made from a high impact
polystyrene because of its desired stiffness. The polystyrenic
layer 18 may be biaxially orientated so as to provide additional
durability and flexibility.
[0045] FIG. 5 depicts a sheathing 50 that is similar to the
sheathing 40 of FIG. 4 except that the sheathing 50 includes an
additional impact polystyrenic layer 18. Sheathing 60 of FIG. 6
comprises the same five layers of the sheathing 50 of FIG. 5. The
sheathing 60 of FIG. 6, however, also comprises two additional
layers. Specifically, the sheathing 60 includes an additional
adhesive layer 16 and a polymeric film layer 20. To provide
additional strength and durability, the polymeric film layer 20 may
be made from a polyolefin(s) such as polypropylene.
[0046] Other layers are contemplated for the sheathings of the
present invention. For example, the sheathings of the present
invention may include radiant barrier layers or flame retardant
layers.
Properties of the Sheathing
[0047] The sheathings of the present invention generally have a
flexural strength of at least 100 lbs./in..sup.2, preferably at
least 150 lbs./in..sup.2 and most preferably at least 200
lbs./in..sup.2 as measured by ASTM D1307. The sheathings of the
present invention have excellent strength so as to provide
resistance to high winds. The sheathings of the present invention
preferably satisfy the structural design requirements as set forth
in the H.U.D. Guide for Manufactured Home Standards Programs (9th
edition, Dec. 1994) for Wind Zone II conditions (a design wind
speed of 100 miles per hour) taken from .sctn. 3280.305(c) of the
Federal Register. The sheathings also preferably satisfy the
structural design requirements as set forth in H.U.D. Guide for
Manufactured Home Standards Programs (9th edition, Dec. 1994) for
Wind Zone III conditions (a design wind speed of 110 mph) taken
from .sctn. 3280.305(c) of the Federal Register.
[0048] The sheathings of the present invention may be formed into a
number of shapes. For example, the sheathing may be a flat sheet or
a folded or hinged board (typically referred to as a fanfolded
sheathing). The fanfold sheathing is designed to unfold at its
hinges and includes a number of individual panels.
[0049] The sheathings of the present invention may be manufactured
in a variety of sizes. Popular sizes used in the housing market
include a 4 foot by 7 foot (4'.times.7'), 4'.times.71/2',
4'.times.8' and 4'.times.9' flat sheets. Other popular sizes in the
housing market include a 4'.times.50'' fanfolded sheathing which
includes a number of individual panels. If a fanfolded sheathing is
used, it is preferred to have cross-members in the wall supporting
structure for which the fanfolded sheathing may be attached.
[0050] The thickness of the sheathings may also vary. The thickness
of the sheathing is generally from about 1/4 of an inch to about 3
inches as measured by ASTM C303. The thickness of the sheathing is
preferably from about 1/4 of an inch to about 3/4 of an inch as
measured by ASTM C303.
[0051] The layers of the sheathings typically vary in their
respective weight percent relative to each other. The sheathings
generally comprise from about 2 wt.% to about 30 wt.% of the
polymeric scrim layer(s) 12. The sheathings generally comprise from
about 25 wt.% to about 99 wt.% of the polymeric foam layer(s) 14.
The sheathings generally comprise from 0 wt.% to about 15 wt.% of
the adhesive layer(s) 16. It is contemplated that the remainder of
the sheathings may include other optional layers. The sheathings
generally comprise from 0 wt.% to about 50 wt.% of the impact
polystyrenic layer(s) 18 and from 0 wt.% to about 50 wt.% of the
polymeric film layer(s) 20.
[0052] The sheathings preferably comprise from about 2 to about 25
wt.%, and most preferably from about 4 wt.% to about 20 wt.% of the
polymeric scrim layer(s) 12. The sheathings preferably comprise
from about 30 to about 95 wt.%, and most preferably from about 40
wt.% to about 90 wt.% of the polymeric foam layer(s) 14.
Preferably, the sheathings comprise from about 1 to about 10 wt.%,
and most preferably from about 1 wt.% to about 7 wt.% of the
adhesive layer(s) 16. The sheathings preferably comprise from about
5 to about 35 wt.%, and most preferably from about 5 wt.% to about
30 wt.% of the impact polystyrenic layer(s) 18. The sheathings
preferably comprise from 0 to about 25 wt.%; and most preferably
from 0 wt.% to about 20 wt.% of the polymeric film layer(s) 20.
[0053] The sheathings of the present invention may be used in
various buildings such as prefabricated housing (also referred to
as manufactured housing), site built housing, and remodeling. The
sheathing may be installed to a wall supporting structure. An
example is shown in FIG. 7 where a sheathing 52 is installed to a
plurality of wall supporting structures 22 using the polymeric
scrim layer 112 of FIG. 2a. The sheathing 52a has been cut-away to
depict the various layers 112, 14, 16 and 18, while sheathing 52b
has not been cut-away in FIG. 7. FIG. 7 also shows siding 56 being
located on an exterior surface of the sheathing 52.
[0054] The sheathing 52 of FIG. 7 may be installed to the plurality
of wall supporting structure 22 by the use of fasteners (not
shown). The fastener may be a mechanical fastener such as a staple
or nail. According to the embodiment depicted in FIG. 7, the
polymeric scrim layer 112 of the sheathing 52 includes a first
portion 102, a second portion 104, and a third portion 106 opposite
the second portion 104. The second and third portions 104, 106 are
located generally parallel to the wall supporting structure 22.
[0055] It is contemplated that the sheathing of the present
invention may be used in a roofing application to provide
additional strength, to resist wind uplift and to provide
durability that minimizes breakage during handling and
installation. The sheathing may be used as an underlayment for low
slope roofs.
PROCESS OF THE PRESENT INVENTION
[0056] According to one process of the present invention, a
polymeric web of foam is provided to form the polymeric foam layer.
The process may use a single twin screw extruder or a tandem foam
extrusion line. For example, the process begins by loading pellets
of a polymeric resin(s) such as polystyrenic foam resin. The
polymeric resins in their solid form are added into an extrusion
hopper.
[0057] A nucleating agent (also referred to as cell size control
agent) or combination of such nucleating agents may be employed in
the process of the present invention for advantages such as their
capability for regulating cell formation and morphology. The amount
of nucleating agent to be added depends upon the desired cell size,
the selected blowing agent and the density of the polymeric
composition. Known nucleating agents such as talc, mixtures of
sodium bicarbonate and citric acid, and the like may be employed in
the present invention.
[0058] It is contemplated that stability control agent(s) may also
be added to the polymeric resin(s), including conventional
stability control agents. Some examples of stability control agents
that may be used include, but are not limited to, glycerol
monostearate, saturated higher fatty acid amides and glycerol
monoester of a C.sub.20-C.sub.24 fatty acid.
[0059] If desired, fillers, colorants, light and heat stabilizers,
plasticizers, chemical blowing agents, flame retardants, foaming
additives and plastic compounding agents may be added to the
polymeric composition. The polymeric composition comprises the
polymeric resin and, if added, the nucleating agent, the stability
control agent and additives. The polymeric composition is conveyed
through a feed zone of the extruder and heated at a temperature
sufficient to form a polymeric melt.
[0060] A physical blowing agent may be added at the injection port
area of the extruder in an appropriate ratio to the target density.
The selected blowing agent may be any type that is capable of
producing foam with the selected resin. Some examples of blowing
agents include physical blowing agents such as halocarbons,
hydrocarbons or combinations thereof. Examples of these include
commercially available hydrofluorocarbons, such as HFC-152a and
HFC-134a, hydrochlorofluorocarbons, such as HCFC-22 or HCFC-142b,
and the C.sub.3-C.sub.6 hydrocarbons. Other types of blowing agents
include carbon dioxide. The polymeric composition and the selected
blowing agent are thoroughly mixed within the extruder in a mixing
zone and subsequently cooled in a cooling zone. The cooled
polymeric-blowing agent melt is extruded thorough a die.
[0061] One method of the present invention for making a three-layer
sheathing is shown in a schematic flow diagram in FIG. 8. In the
process of FIG. 8, the polymeric foam is extruded from an extruder
70 through a round die 72. After exiting the round die 72, the
extrudate expands when entering a lower pressure region (e.g., the
atmosphere) and forms a polymeric web of foam. The polymeric web of
foam is stretched over a sizing mandrel 74 to size and then is slit
to form the web of foam. The polymeric web of foam will eventually
be used in forming the polymeric foam layer 14.
[0062] At least one of the outer surfaces of the polymeric web of
foam is typically cooled so as to form a "skin." The skin is
typically about a few thousands (or a few mils) thick, but may vary
depending on the cooling employed. The skin provides additional
strength and also provides a smoother surface that is more
aesthetically pleasing to a consumer if the polymeric layer is
visible to the customer. It is contemplated that cooling methods
may be accomplished by using air and water. The skinning may be
performed, for example, by stretching the polymeric foam of web 76
over the sizing mandrel 74 with optional cooling wherein either
surface of the polymeric foam of web 76 is cooled. It is
contemplated that one or more of the surfaces of the polymeric web
of foam may be cooled.
[0063] The polymeric foam web 76 proceeds to travel around a S-wrap
of rollers 78 a-c in which roller 78a is an idler roller and
rollers 78b and 78c are driven or pull rollers. The driven rollers
78b, 78c assist in moving the polymeric foam web 76 through the
process of the present invention. The polymeric foam web 76
proceeds between two driven rollers 80 a,b. Driven rollers 80 a,b
assist in maintaining a consistent surface on which a web of
adhesive 82a is added via an adhesive coating or a laminating
machine 82. The adhesive machine 82 may be any conventional machine
that is capable of applying the adhesive web 82a to the polymeric
foam web 76. The adhesive machine 82 may coextrude the web of
adhesive 82a with a second web, such as a web of impact polystyrene
(not shown).
[0064] At the about the same time, a web of scrim 84a is added via
a roll unwind cart system 84. The cart system 84 may include an
edge alignment system to properly align the web of scrim 84a to the
polymeric foam web 76. After exiting the driven rollers 80 a,b, the
polymeric foam web 76, the web of adhesive 82a, and the web of
scrim 84a form a sheathing web 86.
[0065] It is contemplated that the sheathing web 86 may be
processed to include printing on one or more surfaces or other
treatments. The process of FIG. 8 includes an optional printer 88
that prints on one surface of the sheathing web 86. It is
contemplated that the printing may occur on the polymeric foam web
76 before the webs of adhesive and scrim are added to the polymeric
foam web 76. The sheathing web 86 proceeds around a series of
rollers 90a-90d and then to an optional edge trim system 92. The
edge trim system assists in sizing the sheathing web 86 to be used
in forming the sheathing of the present invention.
[0066] As shown in FIG. 8, the sheathing web 86 proceeds through an
optional perforating creasing machine 94. The perforating creasing
equipment 94 may include any conventional equipment that is capable
of folding the sheathing web 86 of the present invention into a
fanfold sheathing web. Of course, if flat sheathing is desired, the
creasing equipment 94 should not be included in the process. A
perforating machine, however, may be used in producing a flat
sheathing. The sheathing web is then cut to a desired dimension by
shearing equipment 96. The shearing equipment 96 may be any
equipment capable of cutting the sheathing web 86 into desired
dimensions. It is also contemplated that other finishing operations
may occur such as stacking, counting, packaging and trimming. It is
also contemplated that various measurements may be taken throughout
the process to ensure consistent measurements.
[0067] According to a second process of the present invention (not
shown), additional layers may be added in forming other sheathings,
such as those described above. For example, a machine (not shown)
may be added to the process of FIG. 8 that is adapted to add an
additional impact polystyrenic web to the polymeric web of
foam.
EXAMPLES
Example 1
[0068] Negative wind pressure load tests were conducted on samples
of sheathing ("Sheathing 1") using a 2.times.4 (1 1/2
inches.times.3 1/2 inches) stud wall supporting structure.
Sheathing 1 had dimensions of 48 inches by 90 inches
(48''.times.90''). Sheathing 1 consisted of five layers with the
first layer being a woven polypropylene scrim having a scrim count
of 28.times.4. The second layer was made of a BYNEL.RTM. adhesive.
The third and fifth layers were made of high impact polystyrene.
The second layer was located between the first and third layers.
The fourth layer was a polystyrene foam and was located between the
third and fifth layers. This is a similar structure as shown above
in FIG. 7. The following describes the test specimens that were
used in Example 1.
[0069] Example 1 Specimen Description
[0070] A. Materials [0071] 1. Stud: Double 2.times.4, Stud Grade
spruce pine fur (SPF) spaced at 16'' on center (o.c.) [0072] 2. Top
Plate: Single 1.times.4, Ungraded SPF [0073] 3. Bottom Plate:
Single 1.times.4, Ungraded SPF [0074] 4. Gypsum:
5/16''.times.48''.times.90'' Georgia Pacific [0075] 5. Siding:
Georgia Pacific 4.5 Lap Vinyl Siding with a nailing flange
thickness of 0.036 inch [0076] 6. Adhesive: PVA
[0077] B. Fastening [0078] Top plate attached to studs with three
(3)- 7/16''.times.1 3/4''.times.15 gauge (Ga.) Staples. [0079]
Bottom plate attached to studs with three (3)- 7/16''.times.1
3/4''.times.15 Ga. Staples. [0080] Sheathing 1 fastened with
1''.times.1 1/2''.times.16 Ga. staples at 3'' o.c. on single
framing members. [0081] Gypsum fastened to studs with
3/16''.times.1''.times.19 Ga. staples at 16'' o.c. per strip of
siding. [0082] Gypsum glued to frame with a 3/8'' bead of PVA glue
on all framing members. [0083] Siding fastened to Sheathing 1 into
the studs with 7/16''.times.1 1/2''.times.16 Ga. staples at 16''
o.c. per strip of siding.
[0084] C. Construction
[0085] The 48''.times.90'' test sample was first assembled with
2.times.4 studs that were 87.75 inches long. The top and bottom
plates were 49.5 inches long. Polyethylene sheeting (6 mil) was
placed between the 2.times.4 framing and Sheathing 1. The framing
was then squared with Sheathing 1 and fastened as described above.
The horizontal vinyl siding was fastened through Sheathing 1 and
into the studs. The 5/16'' gypsum was then fastened to the opposite
side of the frame as described above. Glue was allowed to cure for
7 days before the testing began. Materials for the assemblies
tested were commercially purchased products.
[0086] Example 1 Test Setup and Procedure
[0087] The testing was conducted in accordance with the ultimate
load test procedures in H.U.D. Guide for Manufactured Home
Standards Programs (9th edition, Dec. 1994) taken from .sctn.
3280.401(b) of the Federal Register. An 11-1/4'' deep wood box was
built 1'' wider and 1'' longer than the test sample. The top and
bottom plates of the test samples were secured to 2.times.4
ledgers. The test samples were placed vertically on the test
fixture with the vinyl siding facing down and the ledgers bearing
on top of the wood box. The polyethylene sheeting (6 mil) that was
placed between the wall framing and Sheathing 1 was sealed to the
table. This allowed the entire surface of Sheathing 1 to be exposed
to the full negative loads.
[0088] The uniform load was applied by evacuating the air below the
test specimen using a vacuum pump. The applied load was measured
with a water manometer capable of reading in 0.1 inch increments.
The load was applied in approximate 1/4 design live load increments
at 10 minute intervals until 1.25 times design load was reached.
The load was then increased to 2.5 times design load or until
failure occurred. The load in inches of water column was converted
to pounds per square foot (psf) by using the conversion of 1 inch
(of water column) to 5.2 psf.
[0089] Deflection readings were taken using dial indicators capable
of reading in 0.001'' increments. The deflections were taken at the
quarter-points of the center stud.
[0090] Example 1 Results
[0091] Three specimens (S1, S2, and S3) using 5/16'' Georgia
Pacific Gypsum were tested for corner Wind Zone III requirements.
The product sold by Georgia Pacific Corporation that was used was
5/16'' PreDeck.RTM. Gypsum Board. The ultimate load in pounds per
square foot (psf) was determined in accordance with H.U.D. Guide
for Manufactured Home Standards Programs (9th edition, Dec. 1994)
taken from .sctn. 3280.401(b) of the Federal Register. The average
of these three specimens is shown under the "AVG." column. The
results are as follows in Table 1. TABLE-US-00001 TABLE 1 ULTIMATE
EXPER. LOAD (PSF) AVG. DEFLECTION NO. S1 S2 S3 (PSF) (PASS/FAIL)
WINDZONE 1 156 150.8 161.2 156 PASSED III Corner
[0092] The samples in Experiment 1 satisfied the ultimate load
under a corner condition for Wind Zone III. In addition, the
samples in Experiment 1 also passed the deflection test under a
comer condition for Wind Zone III. The ultimate load requirement
for Wind Zone III for a non-corner condition is 115 psf, while the
ultimate load requirement for Wind Zone III for a corner condition
is 145 psf.
Example 2
[0093] Negative wind pressure load tests were conducted on samples
of 48''.times.90'' Sheathing 1 (described above in Example 1). The
following describes the test specimens that were used in Example
2.
[0094] Example 2 Specimen Description
[0095] A. Materials [0096] 1. Stud: 2.times.4, Stud Grade SPF
spaced at 16'' o.c. [0097] 2. Top Plate: Single 1.times.4, Ungraded
SPF [0098] 3. Bottom Plate: Single 1.times.4, Ungraded SPF [0099]
4. Gypsum: 5/16''.times.48''.times.90'' Gypsum, Georgia-Pacific
[0100] 5. Siding: Georgia Pacific 4.5 Lap Vinyl Siding with a
nailing flange thickness of 0.036 inch [0101] 6. Adhesive: PVA
[0102] B. Fastening [0103] Top plate attached to studs with three
(3)- 7/16''.times.13/4''.times.15 Ga. Staples. [0104] Bottom plate
attached to studs with three (3)- 7/16''.times.13/4''.times.15 Ga.
Staples. * Sheathing 1 fastened with 1''.times.11/2''.times.16 Ga.
staples at 3'' o.c. on framing members. [0105] Gypsum fastened to
studs with 3/16''.times.1''.times.19 Ga. Staples at 16'' o.c. per
strip of siding. [0106] Gypsum glued to frame with a 3/8'' bead of
PVA glue on all framing members. [0107] Siding fastened to
sheathing into the studs with 7/16''.times.11/2''.times.16 Ga.
staples at 16'' o.c. per strip of siding.
[0108] C. Construction
[0109] The construction was similar to that described above in
Example 1.
[0110] Example 2 Test Setup and Procedure
[0111] The test setup and procedure were similar to that described
above in Example 1.
[0112] Example 2 Results
[0113] Three specimens (S1, S2, S3) using 5/16'' Georgia-Pacific
Gypsum were tested for non-comer Wind Zone III requirements. The
results are as follows in Table 2. TABLE-US-00002 TABLE 2 ULTIMATE
EXPER. LOAD (PSF) AVG. DEFLECTION NO. S1 S2 S3 (PSF) (PASS/FAIL)
WINDZONE 2 135.2 140.4 135.2 136.9 PASSED III Non- Corner
[0114] The samples in Experiment 2 passed the requirement for
ultimate load under a non-comer condition for Wind Zone III. In
addition, the samples in Experiement 2 also passed the deflection
test under a non-comer condition for Wind Zone III.
[0115] While the present invention has been described with
reference to one or more particular embodiments, those skilled in
the art will recognize that many changes may be made thereto
without departing from the spirit and scope of the present
invention. Each of these embodiments and obvious variations thereof
is contemplated as falling within the spirit and scope of the
claimed invention, which is set forth in the following claims.
* * * * *