Note: Descriptions are shown in the official language in which they were submitted.
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EXTRUDED POLYSTYRENE FOAM INSULATION
WITH HIGH THERMAL RESISTANCE
This invention relates generally to laminated foam insulation boards
having a foam core with spaced-apart and generally parallel major planar or
primary
surfaces, at least one of which has a facer adhered or bonded thereto. This
invention
particularly relates to such boards wherein the foam core comprises an alkenyl
aromatic polymer such as polystyrene. This invention more particularly relates
to such
laminates that exhibit improvement, relative to the foam core alone, in at
least one of
stiffness, impact resistance, strength and resistance to bending and breaking
together
with an improvement in long term thermal resistance.
An improved laminated foam insulation board having enhanced strength
and resistance to bending and breaking is disclosed in U.S. Patent No. (USP)
5,695,870, assigned to The Dow Chemical Company, the assignee of the present
invention. The insulation board includes a panel of a plastic foam material
and first
and second thermoplastic facers adhered to both primary surfaces of the panel.
Each
facer has an ultimate elongation of less than (c) 200 percent (%) in both
machine and
transverse directions, a yield strength of at least (>) 7,000 pounds per
square inch
(psi)(48,400 (kilopascals kPa)) in both machine and transverse directions (MD
and TD
respectively), and a 1 percent secant modulus > 200,000 psi (1,380 megapascals
(mPa)) in both MD and TD. The degree of adhesion between each of the facers
and
the foam panel is expressed as a peel strength of > 100 grams per inch
(g/in)(39.4
grams per centimeter (g/cm)). Determine peel strength using a 180° peel
test
(American Society for Testing and Materials (ASTM) test D-903). Suitable films
having
the required properties include biaxially oriented polyolefin, alkenyl
aromatic polymer,
polyester, polycarbonate, acrylic polymer, and polyamide films having a
thickness of
from 0.35 to 10 mils (10 to 250 micrometers (~.m)). The disclosed laminates
exhibit
significantly improved resistance to bending and breaking as compared with
previously
known insulation boards with facers that do not have the required elongation,
yield
strength, and one percent secant modulus.
The laminated foam insulation boards of USP 5,695,870, like most
previously known foam insulation boards, exhibit significant thermal
resistance losses
after manufacture as the facers are not substantially impervious to the
passage of gas.
As a result, air infiltrates into the cells of the foam panel and/or blowing
agent migrates
from the cells, diluting the insulating effect of the blowing agent which
typically exhibits
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better resistance to heat flow than air. Thus, the infiltration of air into,
and/or the
escape of blowing agent from, the cells of the foam panel cause a substantial
loss in
the thermal resistance of the laminated foam insulation board. Typically the
thermal
resistance of laminated foam insulation boards is 15 to 20 percent lower six
months
after manufacture than it is at the time of manufactured.
Laminated foam insulation boards that comprise a plastic foam panel
attached to a facer (at least one vinylidene chloride copolymer layer) that is
substantially impervious to the passage of air have been found to retain
higher thermal
resistance over a longer period of time. However, such known laminated foam
insulation boards do not exhibit the desired physical strength and abuse
resistance.
The present invention is a laminated insulating foam board comprising a
panel of a plastic foam material; and at least one facer film adhered to a
primary
surface of the panel, wherein the facer has an oxygen transmission rate of
less than
10 cubic centimeters per 100 square inches of facer per 24 hour period per
atmosphere of pressure (cc/100 in2-24 hrs-atm) (2.36 x 10-9 cc/cm2-second-
centimeter
of mercury (cc/cmz-sec-cm Hg)), an elongation of less than 200 percent in both
machine and transverse directions, a yield tensile strength of at least 7,000
pounds per
square inch (48,400 kPa) in both machine and transverse directions, and a 1
percent
secant modulus of at least 200,000 pounds per square inch (1,380 megapascals)
in
both machine and transverse directions.
The facer provides the laminated insulating foam boards with both a low
gas transmission rate, especially to oxygen, and sufficient strength to resist
bending
and breaking.
Figure (FIG.) 1 is a perspective view of a foam laminate board of the
present invention.
FIG. 2 is an enlarged, fragmentary, cross-sectional view of the board of
FIG. 1 along a line 2-2.
FIG. 3 is an enlarged, fragmentary, cross-sectional view of the board of
FIG. 1 along a line 2-2 as in FIG. 2, but with a composite facer.
FIG. 1 simply shows a schematic illustration, in perspective view, of a
foam laminate board 10 suitable for purposes of the present invention. FIG 1
also
shows a section line 2-2 to better illustrate both a monolayer facer in FIG. 2
and a
multilayer facer in FIG. 3.
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FIG. 2 shows a foam laminate board 10 that comprises a foam core 14
with a first facet 16 bonded to a one primary surface of foam core 14 and a
second
facet 18 bonded to a second primary surface of foam core 14. As shown in FIG.
2, the
primary surfaces of foam core 14, and consequently first facet 16 and second
facet 18,
are spaced apart from, and generally parallel to, one another.
FIG. 3 shows an alternate foam laminate board 10' that comprises a
foam core 14' with a first composite facet 15 bonded to one primary surface of
foam
core 14' and a second composite facet 17 bonded to a second primary surface of
foam
core 14'. The foam core 14' and the first and second composite facets 15 and
17
relate to each other in the same manner as their counterparts do in FIG. 2.
First
composite facet 15 includes a foam contact layer 16' and an external surface
layer 20.
Second composite facet 17 includes a foam contact layer 18' and an external
surface
layer 22.
While facets 16 and 18 may be formed from different polymer
compositions, preferred results follow when they are formed from the same
composition. Similarly, foam contact layers 16' and 18' preferably have the
same
composition and external layers 20 and 22 preferably have the same
composition.
Minimizing composition differences provides benefits such as ease of
manufacture,
reduced cost, and product uniformity. If desired, however, facets 16 and 18
and
composite facets 15 and 17 may result from different polymer compositions. The
laminated foam insulation board exhibits a substantially improved combination
of
physical strength, abuse resistance, and improved long-term thermal resistance
as
compared with known insulating foam boards.
Laminated foam insulation boards having desirable strength, abuse
resistance, and long-term thermal resistance can be made by laminating a facet
to
both sides of a foam core. The facets exhibit a combination of low gas
transmission
rate, low elongation, and high tensile strength. More specifically, the facets
exhibit an
oxygen transmission rate (02TR) of less than (<) 10 cc/100 in2-24 hrs-atm
(2.36 x 109
cc/cm2-sec-cm Hg), an elongation of < 200 percent in both machine and
transverse
directions, a yield tensile strength of > 7,000 pounds per square inch (psi)
(48,400
kilopascals (kPa)) in both machine and transverse directions, and a 1 percent
secant
modulus > 200,000 psi (1,380 megapascals (mPa)) in both machine and transverse
directions. The required combination of properties enables the foam insulation
board
to withstand a variety of mechanical stresses such as impact, bending, and
torsion,
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while also retaining high thermal conductivity over an extended period of
time. The
facers prevent or substantially reduce the likelihood of fracture propagation
at the foam
panel/facer interface, and are substantially impervious to the passage of gas.
The facer oxygen transmission rate (02TR) is preferably < 6 cc/100 in2-
24 hrs-atm (1.42 x 10~g cc/cm2-sec-cm Hg), more preferably < 2 cc/100 in2-24
hrs-atm
(4.72 x 10-'° cc/cm2-sec-cm Hg). The facer is preferably a composite of
two or more
layers, one of which provides a gas (oxygen) barrier. The gas barrier layer
has a
thickness that varies with the resin used to prepare the layer, but is
sufficient to
provide the composite with the 02TR specified above.
The desired combination of enhanced strength and improved long-term
thermal resistance can be achieved using composite facers 15 and 17. Composite
facer 15 includes a foam contact layer 16' that provides the elongation,
tensile yield
strength and 1 percent secant modules properties specified above and a gas
barrier
layer 20 that provides the oxygen transmission rate performance specified
above.
Composite facer 17 includes foam contact layer 18' and gas barrier layer 22.
Foam
contact layers 16' and 18' are preferably identical to each other as are gas
barrier
layers 20 and 22.
Although foam board 10' includes composite facer 15 with a high
strength, low elongation film layer 16' laminated directly to both foam panel
14' and
gas barrier layer 20, skilled artisans understand that various modifications
are possible
without departing from the spirit and scope of the invention. For example,
either or
both of composite facers 15 and 17 can comprise additional layers, including a
layer or
layers between foam contact or high strength layer 16' or 17' and the
respective gas
barrier layers 20 and 22, a layer or layers between the foam panel and the
high
strength layer and/or oxygen barrier layer, and/or a layer or layers overlying
the high
strength layer and gas barrier layer. Such additional layers may be
incorporated to
provide additional functional or aesthetic qualities, with specific examples
including
additional thermoplastic layers, metal layers, kraft paper, fibrous layers,
including
woven and non-woven fabrics, and batts. Also, the high strength layer may be
disposed between the foam panel and gas (especially oxygen) barrier layer, as
illustrated, or, alternatively, the gas barrier layer may be disposed between
the foam
panel and the high strength layer, with or without additional layers. One or
more
adhesive layers, which may be the same or different from each other, may be
used to
bond the various layers of the facer together and/or to the foam panel.
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The high strength plastic layer may comprise any thermoplastic polymer
as long as it meets the physical property criteria and can be effectively
laminated to a
foam panel. The high strength plastic layer may comprise a polyolefin, alkenyl
aromatic polymer, polyester, polycarbonate, acrylic polymer, or polyamide
polymer.
Useful polyolefins include polyethylene and polypropylene. Useful
polyethylenes
include high density polyethylene (HDPE), low density polyethylene (LDPE), and
linear
low density polyethylene (LLDPE). Useful high strength plastic layers are
generally
biaxially oriented. Preferred high strength plastic layers include biaxially
oriented
polyethylenes, polypropylenes, polyesters, polystyrene, or polyamides. The
high
strength plastic film layer may be crosslinked or non-crosslinked. The high
strength
plastic film layer optionally contains conventional additives such as
inorganic fillers,
pigments or colorants, antioxidants, ultraviolet stabilizers, fire retardants,
and
processing aids. The high strength plastic film layer typically has a
thickness of from
0.35 mil (10 Vim) to 10 mils (250 Vim), and preferably from 0.5 (13 ~,m) to 3
mils (75
~,m).
For biaxially oriented films, suitable thicknesses are from 0.35 mils (10
~.m) to 10 mils (250 Vim), and preferably from 0.5 mils (13 ~,m) to 1 mil (25
~,m),
whereas for non-oriented films, e.g., HDPE, suitable thicknesses are from 1.5
mils (38
~,m) to 3 mils (75 ~.m), and preferably 1.5 mils (38 ~,m).
The gas barrier layer of the composite facer may comprise any material
that is substantially impervious to the passage of air. More specifically, the
gas barrier
layer should exhibit an oxygen permeability of < 8 cc-mil/100 in2-24 hrs-atm
(4.8 x 10'2
cc-cm/cm2-sec-cm Hg), preferably < 3 cc-mil/100 in2-24 hrs-atm (1.8 x 10-'2 cc-
cm/cm2-
sec-cm Hg), and more preferably < 1 cc-mil/100 in2-24 hrs-atm (6.0 x 10-'3 cc-
cm/cm2-
sec-cm Hg). Examples of suitable gas barrier layers include thermoplastic
films having
the required low oxygen permeability, and metal films formed or deposited on a
primary surface of the high strength plastic film layer.
Examples of suitable thermoplastic materials, which can be used for the
gas, especially oxygen, barrier layer, include ethylene vinyl alcohol
copolymers
(EVOH) and vinylidene chloride (VDC) homopolymers and copolymers. Examples of
VDC copolymers include copolymers that comprise VDC and at least one comonomer
selected from unsaturated monomers copolymerized therewith. Suitable monomers
for copolymerization with VDC include vinyl chloride, acrylonitrile, acrylic
esters, and
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acrylic acids. Copolymers of VDC and vinyl chloride (known as "Saran") are
also
suitable for the oxygen barrier layer.
The gas barrier layer can be either coextruded with the high strength
plastic film layer, or cast on the high strength layer, or laminated to the
high strength
film. Gas barrier layers comprised of EVOH are most preferably coextruded with
a
high strength plastic film layer, such as a polypropylene (PP) or HDPE film
layer.
Coextrusion provides excellent adhesion between the high strength layer and
the gas
barrier layer. VDC homopolymers and copolymers are most preferably cast on the
high
strength plastic film layer, such as by spraying a solution containing
solubilized VDC
homopolymer or copolymer onto the high strength plastic film layer and
allowing the
solvent to evaporate. Although it is preferred to form the gas barrier layer
directly on
the high strength plastic film layer, such as by coextrusion or casting,
composite facers
having the desired strength and low oxygen barrier transmission properties can
be
prepared by attaching a gas barrier layer to the high strength plastic film
layer with an
intervening adhesive layer. It is also possible to separately form a high
strength plastic
film layer and a gas barrier layer and subsequently thermally fuse the layers
together,
such as with application of heat and pressure. The gas barrier layer can be,
and
preferably is, < 1 mil (25 ~,m) thick, and more preferably < 0.5 mil (13 Vim)
thick, with
suitable low gas (e.g. oxygen) transmission rates being achievable with films
having a
thickness of from 0.1 mil (2.5 ~,m) to 0.2 mil (5 ~,m).
A vacuum-deposited metal film provides an alternate gas barrier layer
with a sufficiently low 02TR. Although the metal film can be vacuum-deposited
onto a
film that does not have the desired high strength properties, and subsequently
laminated to a high strength film, such as with adhesives or by thermal
bonding by
application of heat and pressure, preferred practice vacuum-deposits the metal
film
directly onto a primary surface of the high strength plastic film layer.
Suitable vacuum-
deposition techniques include sputtering, glow discharge, evaporation, vapor
plating,
and ion plating. On account of its excellent low O2TR and relatively low cost,
aluminum is a preferred material, for vacuum-deposition. Other suitable metals
include antimony, silver, copper, nickel, beryllium, bismuth, germanium,
hafnium,
magnesium, niobium, tantalum, tin, titanium, tungsten, and zirconium. The
thickness
of the vacuum-deposited metal film typically ranges from 0.1 to 0.5 Vim,
preferably from
0.1 to 0.2 ~,m.
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Although biaxially oriented films are preferred for the high strength
plastic film layer, non-oriented HDPE and PP films can be used as the high
strength
plastic film layer, provided that they have suitable thickness. In the case of
non-
oriented HDPE and PP, a suitable thickness is > 1.5 mils (38 ~.m).
The (film or composite film) facer may be laminated to the present foam
board by any conventional method known in the art. Useful lamination methods
include hot roll lamination of a heat activated adhesive layer onto the facer.
Another
method is liquid coating or spraying coating of a hot melt adhesive or liquid-
based
adhesive onto the facer or foam board prior to lamination. An adhesive melt
may also
be extruded onto the facer or foam prior to lamination. The facer may also be
coextruded with an adhesive layer, and subsequently laminated to the foam
board.
The degree of adhesion between the facer and foam panel is sufficient
to ensure adhesion during impact or bending. Separation or slipping between
the
facer and the foam panel at their interface negates the strengthening effect
of the
facer. The degree of adhesion between the facer and foam board is preferably
such
that any failure occurs within the foam rather than in the facer upon bending
of the
laminate board. The degree of adhesion is preferably high enough that part or
all of the
skin of the foam can be pulled off the remainder of the foam when the film is
peeled off
the foam. The adhesive must adhere to both the facer and the foam panel
substrate.
The degree of adhesion (or peel strength) is > 100 gm/in. (39.4 gm/cm)
preferably >
250 gm/in. (98.5 gm/cm), according to the 180° peel test (ASTM D-903).
Suitable materials for use as adhesives or in adhesive layers include
those adhesive materials known in the art as useful with plastic films and
foams. They
include polyolefin copolymers such as ethylene/vinyl acetate (EVA),
ethylene/acrylic
acid (EAA), ethylene/n-butyl acrylate, ethylene/methylacrylate, ethylene
ionomers, and
ethylene or propylene polymers grafted with an anhydride. Other useful
adhesives
include urethanes, copolyesters and copolyamides, styrene block copolymers
such as
styrene/butadiene and styrene/isoprene polymers, and acrylic polymers. The
adhesives may be thermoplastic or curable thermoset polymers, and can include
tacky, pressure-sensitive adhesives. The adhesive layer is preferably
recyclable within
the foam board manufacturing process. The adhesive material desirably has no
significant negative impact upon the physical integrity or properties of the
foam.
The foam panel or foam core stock of the present foam board may take
the form of any insulation foam known in the art such as extruded polystyrene
foam,
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molded expanded polystyrene (MEPS) foam, extruded polyolefin foam, expanded
polyolefin bead foam, polyisocyanurate foam, and polyurethane foam.
The present invention is particularly useful with extruded polystyrene
foam and MEPS foam. Such foams are readily recyclable and thermoplastic facets
and adhesive materials are readily recyclable with the foams. Recyclability
means the
foams can be ground into scrap, which can be melted and processed with virgin
polymer materials, blowing agents, and additives to form new foams. The facets
also
substantially enhance the strength of thin polystyrene foam boards useful in
insulating
sheeting applications, particularly those boards of thickness of from greater
than zero
inch up to and including 4 in (10.2 cm), desirably from'/a in to 4 in (0.64
centimeter
(cm) to 10.2 cm).
Polystyrene foams may be derived from conventional alkenyl aromatic
polymer materials. Suitable alkenyl aromatic polymer materials include alkenyl
aromatic homopolymers and copolymers of alkenyl aromatic compounds and
copolymerizable ethylenically unsaturated comonomers. The alkenyl aromatic
polymer material may further include minor proportions of non-alkenyl aromatic
polymers. The alkenyl aromatic polymer material may comprise one or more
alkenyl
aromatic homopolymers, one or more alkenyl aromatic copolymers, a blend of one
or
more each of alkenyl aromatic homopolymers and copolymers, or blends of any of
the
foregoing with a non-alkenyl aromatic polymer. Regardless of composition, the
alkenyl
aromatic polymer material comprises > 50, preferably > 70, wt percent alkenyl
aromatic monomeric units, based on total polymer weight. Most preferably, the
alkenyl
aromatic polymer material comprises 100 wt percent alkenyl aromatic monomeric
units.
Suitable alkenyl aromatic polymers include those derived from alkenyl
aromatic compounds such as styrene, alpha-methylstyrene, ethylstyrene, vinyl
benzene, vinyl toluene, chlorostyrene, and bromostyrene. A preferred alkenyl
aromatic polymer is polystyrene. Minor amounts of monoethylenically
unsaturated
compounds, such as C2_6 alkyl acids and esters, ionomeric derivatives and C4_6
dienes may be copolymerized with alkenyl aromatic compounds. Examples of
copolymerizable compounds include acrylic acid, methacrylic acid, ethacrylic
acid,
malefic acid, itaconic acid, acrylonitrile, malefic anhydride, methyl
acrylate, ethyl
acrylate, isobutyl acrylate, n-butyl acrylate, methyl methacrylate, vinyl
acetate and
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butadiene. Preferred foams comprise substantially (i.e., > 70 wt percent),
more
preferably > 95 wt percent and most preferably entirely of polystyrene.
Extruded polymer foam preparation generally involves heating a
polymer material to form a plasticized or melt polymer material, incorporating
therein a
blowing agent to form a foamable gel, and extruding the gel through a die to
form the
foam product. Heating the polymer material to a temperature at or above its
glass
transition temperature or melting point typically precedes blowing agent
addition.
Blowing agent incorporation into or admixture with a polymer melt material may
use
any means known in the art such as with an extruder, mixer, or blender. Mix
the
blowing agent with the polymer melt material at an elevated pressure
sufficient to
prevent substantial expansion of the polymer melt material and to generally
disperse
the blowing agent homogeneously therein. Optionally, blend a nucleator in the
polymer melt or dry blend the nucleator with the polymer material prior to
plasticizing
or melting. Typical procedures cool the foamable gel to a lower temperature to
optimize physical characteristics of the foam structure. Gel cooling may occur
in the
extruder or other mixing device or in separate coolers. Extrude or conveyed
the
foamable gel through a die of desired shape to a zone of reduced or lower
pressure to
form the foam structure. The zone of lower pressure is at a pressure lower
than that in
which the foamable gel is maintained prior to extrusion through the die. The
lower
pressure may be superatmospheric, subatmospheric (evacuated or vacuum), or at
an
atmospheric level.
Form MEPS foams by expanding pre-expanded beads that contain a
blowing agent. Mold the expanded beads at the time of expansion to form
articles of
various shapes. Processes for making pre-expanded beads and molded expanded
bead articles are taught in Plastic Foams, Part II, Frisch and Saunders, pp.
544-585,
Marcel Dekker, Inc. (1973) and Plastic Materials, Brydson, 5th ed., pp. 426-
429,
Butterworths (1989), the teachings of which are incorporated herein by
reference.
Thermoplastic Pacer films, while particularly useful for lamination to
polystyrene foam boards, also yield enhanced strength when laminated to
polyisocyanurate and polyurethane foam boards. Barrier facers help to maintain
the
R-value of such boards in the same way as they do on polystyrene foam boards.
Prepare polyurethane and polyisocyanurate foam structures by reacting
two preformulated components, commonly called an A-component and a B-
component. The preformulated components comprise an isocyanate and a polyol.
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Polyurethane foam preparation involves a reaction between a polyol
and an isocyanate on a 0.7:1 to 1.1:1 equivalent basis. Polyisocyanurate foam
preparation includes a reaction between a polyisocyanate and a minor amount of
polyol to provide 0.10 to 0.70 hydroxyl equivalents of polyol per equivalent
of
polyisocyanate. USP 4,795,763, the teachings of which are incorporated herein,
discloses useful polyurethanes and polyisocyanurates as well as their
preparation.
Blowing agent selection is not critical to the present invention. Blowing
agents useful in making a foam board vary depending upon the composition of
the
foam and can include inorganic blowing agents, organic blowing agents and
chemical
blowing agents. Suitable inorganic blowing agents include carbon dioxide,
argon, and
water. Organic blowing agents include aliphatic hydrocarbons having 1-9 carbon
atoms (C,_9), C,_3aliphatic alcohols, and fully and partially halogenated
C,_Qaliphatic
hydrocarbons. Particularly useful blowing agents include n-butane, isobutane,
n-
pentane, isopentane, ethanol, chlorodifluoromethane (HCFC-22), 1,1-
difluoroethane
(HFC-152a), 1,1,1,2-tetrafluoroethane (HFC-134a), ethyl chloride, 1,1-dichloro-
1-
fluoroethane (HCFC-141 b), and 1-chloro-1,1-difluoroethane (HCFC-142b),
1,1,1,3,3-
pentafluoropropane (HFC-245 fa), 1,1,1,3,3-pentafluorobutane (HFC-365 mfc),
cyclobutane, and cyclopentane. The present invention is particularly useful
when the
blowing agent has a thermal resistance greater than air.
The foam board may have incorporated therein one or more additives
such as inorganic fillers, pigments, antioxidants, acid scavengers,
ultraviolet
absorbers, flame retardants, processing aids, extrusion aids, and the like.
In addition, a nucleating agent may be added in order to control the size
of foam cells. Preferred nucleating agents include inorganic substances such
as
calcium carbonate, talc, clay, titanium dioxide, silica, barium stearate,
diatomaceous
earth, mixtures of citric acid and sodium bicarbonate, and the like. The
amount of
nucleating agent employed may range from 0.01 to 5 parts by weight per hundred
parts by weight of a polymer resin (phr). The preferred range is from 0.1 to 3
phr.
Suitable polystyrene foam densities range from 10 kilograms per cubic
meter (kg/m3) to 150 kg/m3, preferably from 10 kg/m3 to 70 kg/m3 (ASTM D-1622-
88). The polystyrene foam average cell size ranges from 0.1 mm to 5 mm,
preferably
from 0.15 mm to 1.5 mm (ASTM D3576-77).
The polyisocyanurate foams and polyurethane foams have a density
range of from 10 kg/m3 to 150 kg/m3, preferably from 10 kg/m3 to 70 kg/m3
(ASTM D-
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1622-88). The polyisocyanurate foam and polyurethane foam average cell size
ranges
from 0.05 mm to 5.0 mm, preferably from 0.1 mm to 1.5 mm (ASTM D3576-77).
The polystyrene foams may be closed cell or open cell, but are
preferably closed cell, more preferably with a closed cell content >90 percent
(ASTM
D2856-87).
The present foam board may be used to insulate a surface or an
enclosure or building by applying the board to the same. Other useful
insulating
applications include in roofing, refrigeration, and the like.
The following examples illustrate, but do not limit the present invention.
Unless otherwise indicated, all percentages, parts, or proportions are by
weight.
Using extruded polystyrene foam panels having a thickness of 0.56 in
(14 mm), a density of 2 pounds per cubic foot (pcf) (32 kg/m3) and measuring 4
feet by
8 feet (1.2 meter (m) by 2.4 m) as foam cores, laminate facers to both sides
of a foam
core using an EVA copolymer adhesive to form laminated foam boards suitable
for
testing. While the polystyrene foam panels used in the examples all have the
same R-
value when measured on as-extruded foam, Table 2 below shows a discernible R-
value drop-off for some laminates with an "initial" measurement taken at seven
(~ two)
days and a further drop-off after aging for six months (~ five days). The EVA
copolymer has a vinyl acetate content of 18 wt percent, based on copolymer
weight, a
density of 0.95 g/cc and a melt index (ASTM D-1238) of 8.0 dg/min.
Physical property testing of the facers, both composite and monolayer,
focuses upon yield tensile strength, ultimate elongation percentage and 1
percent
secant modulus, all in accord with ASTM D-882. For composite facers, measure
02TR using a Mocon Ox-Tran model 10-50 oxygen permeability tester (ASTM
D3985)after laminating the facer to the foam core. Table I summarizes physical
property test results for composite facers.
Measure an initial R-value of each laminated foam board at seven (~
two) days after extrusion and lamination and an aged R-value at six months (~
five
days) later using a Laser Comp model 304 heat flow meter and ASTM C-518. Table
II
summarizes thermal resistance or R-value measurements.
Subject the laminated foam boards to a "ball drop" test in order to
evaluate resistance to bending and breaking. In this test, individually clamp
each
laminated foam board onto a 4 ft by 8 ft (1.3 m by 2.4 m) horizontal stud or
building
frame wall section with 16 in (41 cm) centers). Drop a 4.32 pound (1.96 kg)
ball
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having a diameter of 3 inches (7.6 cm) from a height of 36 in (91 cm) onto the
center of
each laminated foam board midway between the 16 in (41 cm) centers. Examine
the
boards after the test to determine the extent of damage.
Use a "kneeling" test to simulate a ladder bearing a person leaning
against a foam board attached to a vertically-erected frame wall or a person
or
persons kneeling on a foam board attached to a horizontally-disposed frame
wall as
the frame wall is being constructed.
In the kneeling test, allow several different individuals ranging in weight
from approximately 100 to 200 pounds (45 to 100 kg) to kneel, crawl, or walk
in
sequence (one after the other) upon foam boards between the 16 in (41 cm)
centers of
a horizontally-disposed frame wall. Subjectively evaluate the physical
integrity of the
foam board and its resistance to bending and fracture on a 1-5 scale (1-
fracture
through board; 5-no damage). Test several samples of each foam board and
average
the results.
To evaluate resistance to bending and breaking, subject the laminate
foam boards to the "180° bend" test. In this test, manually bend 1 ft
by 2 ft (30.5 cm by
61.0 cm) pieces of each foam board in half such that the board is bent back
upon
itself. Examine the foam board to see whether it breaks or not.
COMPARATIVE EXAMPLE COMP EX)1
Prepare a 1.0 mil (25 Vim) coextruded film comprising a 0.8 mil (20 ~,m)
thick primary layer and a 0.2 mil (5 Vim) thick adhesive layer on a
conventional upward-
blown film extrusion line at extrusion temperatures of 375°F to
400°F (191°C to
204°C). The primary layer comprises a blend of 85 wt percent LLDPE and
15 wt
percent LDPE. The adhesive layer comprises a blend of 95 wt percent EVA
copolymer and 5 wt percent silicon dioxide (Si02) in the form of a concentrate
(15 wt
percent Si02 in LDPE) as an antiblocking concentrate. Laminate the coextruded
film
to both primary surfaces of an extruded polystyrene foam board (14 mm thick)
with a
hot roll laminator operating at 375°F (191 °C) with the adhesive
layer in contact with the
primary surfaces. The laminate exhibits a peel strength of 250 gm/in. (98.5
gm/cm).
The coextruded film has physical properties as set forth in Table 1.
COMP EX 2
Extrusion coat a 1.0 mil (25 ~.m) biaxially oriented polypropylene film
(OPP) with a uniform 0.4 mil (10 Vim) EVA adhesive layer across the OPP film.
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Thermally laminate the coated film as in Comp Ex 1. The peel strength is > 300
gm/in.
(118.2 gm/cm). The film has physical properties as set forth in Table 1.
EX 3
Prepare a non-oriented composite facer by coextruding HDPE (1 mil
(25 Vim) thick) and EVOH (0.1 mil (2.5 um) thick). Laminate the coextruded
film and to
both primary surfaces of an extruded polystyrene (PS) foam as in Comp Ex 1,
but use
an intervening EVA layer (0.4 mil, (10 Vim) thick).
EX 4
Prepare a composite facer in substantially the manner and set forth in
EX 3, but use a metallized (0.2 pm thick aluminum layer) 0.5 mil (13 ~,m)
thick biaxially
oriented polyethylene terephthalate film that is extrusion coated with an EVA
layer
instead of the HDPE/EVOH/EVA film of EX 3. Laminate the composite facer to
each
of the major surfaces of a PS foam in substantially the same manner as set
forth in
COMP EX 1.
EX 5
Prepare a composite facer by coextruding PP and EVOH. Biaxially
orient the coextruded film. The PP layer has a thickness of 0.5 mil (13 ~.m)
and the
EVOH layer has a thickness of 0.2 mil (5 ~,m). Laminate the composite facer
film to
each of the major surfaces of a polystyrene foam board in substantially the
same
manner as set forth in COMP EX 1.
EX 6
Prepare a composite facer by casting a polyvinylidene chloride (PVDC)
film onto a 0.7 mil (18 ~,m) thick OPP film. Cast the PVDC film by spray
coating a
major surface of the OPP film with a solution containing solubilized PVDC
polymer,
and allowing the solvent to evaporate and to leave a PVDC film with a
thickness of 0.2
mil (5 ~,m). Extrusion coat an EVA adhesive layer onto the OPP side of the
composite
facer as in Comp Ex 2 and laminate the coated composite facer to an extruded
PS
foam board, also as in Comp EX 2.
Table 1 shows the physical properties of the facers of COMP EX 1 and
2, and EX 3-6, and Table 2 shows the R-values for the laminated foam boards of
COMP EX 1 and 2 and EX 3-6.
The laminate foam boards of COMP EX 2 and EX 3 all withstand five
consecutive ball drops without suffering fracture or penetration, whereas the
laminate
foam boards of COMP EX 1 fracture easily by impact of the ball.
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In the "180° bend" test, the foam boards of COMP EX 2 and EX 3-6
all
bend without breaking, whereas the foam boards of COMP EX 1 break prior to
completing the 180° bend.
In the "kneeling" test, the foam boards of COMP EX 1 average a rating
of 2 and 3, respectively, while those of COMP EX 2 and EX 3-6 average between
4
and 5 and exhibit little or no damage.
While the examples and specification provide specific details
about embodiments of laminate foam boards of the present invention, skilled
artisans understand that the present invention may be modified by various
changes while still being fairly within the scope of the novel teachings and
principles herein set forth. Such changes may stem from, for example, a
manufacturer's choice of process conditions, materials or both.
Table 1 shows the physical properties of the facers of COMP EX 1 and
2, and EX 3-6, and Table 2 shows the R-values for the laminated foam boards of
COMP EX 1 and 2 and EX 3-6.
The laminate foam boards of COMP EX 2 and EX 3 all withstand five
consecutive ball drops without suffering fracture or penetration, whereas the
laminate
foam boards of COMP EX 1 fracture easily by impact of the ball.
In the "180° bend" test, the foam boards of COMP EX 2 and EX 3-6
all
bend without breaking, whereas the foam boards of COMP EX 1 break prior to
completing the 180° bend.
In the "kneeling" test, the foam boards of COMP EX 1 average a rating
of 2 and 3, respectively, while those of COMP EX 2 and EX 3-6 average between
4
and 5 and exhibit little or no damage.
While the examples and specification provide specific details about
embodiments of laminate foam boards of the present invention, skilled artisans
understand that the present invention may be modified by various changes while
still
being fairly within the scope of the novel teachings and principles herein set
forth.
Such changes may stem from, for example, a manufacturer's choice of process
conditions, materials or both.
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TABLE 1
PHYSICAL PROPERTIES OF FACERS
Ex/ OZ Tensile StrengthUlt 1%
TR* Yield % Secant
Modulus.
_ Eiona ~si/
Comb psi/mPa
Ex Ava" mPa
MD TD MD TD
Comp 300/
Ex 1810/ 1480/ 550 24.600/31.400/
1 -a
7.08 x
10
12.500 10.2 170 220
Comb 140/ 14.900/ 28.200/ 254.000/424.000/
1 40
Ex 3.30 x 103.000 19 5 1760 2930
2 10-8
1/ 3950/ 3600/ 71.500/92.000/
-
Ex 300
3
2 .36 x 10' 27.300 24. 9 490 640
0.4/ 12.600/ 24.500/ 489.000/565.000/
-
Ex 120
4
9.44 x 87.100 169.4 _ 3380 3900
10'"
_0.5/ 11.900/ 18.600/ 470.000/510.000/
Ex 150
1 .18 x 10-'82.300 128. 6 3250 3520
_0.61 14900/ 28.200/ 260.300/423.000/
_Ex 130
6
1.42 x 103.000 195 _ 1800 2920
10''
* = cc/100 in2-24 hrs-atm / cc/cm2-sec-cm Hg
** Ultimate percent Elongation (Average)
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TABLE 2
Ex/Comp Ex Initial R-Value Aged R-Value
jF-ft= H/BTU)/(K-m2/W)fF-ft~-H/BTU)/(K-m2/W)
Coma Ex 1 3.2/0.56 3.0/0.53
Comp Ex 2 3.6/0.63 3.0/0.53
Ex 3 4.1/0.72 3.8/0.67
Ex 4 4.1/0.72 4.0/0.70
Ex 5 4.1 /0.72 4.1 /0.72
Ex 6 4.0/0.70 4.0/0.70
The R-value data of Table 2 shows that Ex 3-6 begin with higher R-
value than either Comp Ex 1 or Comp Ex 2. The R-value data also show that the
laminates of Ex 5 and 6 retain their R-value after six months, the laminates
of Ex 3 and
4 remain higher than the starting R-values for Comp Ex 1 and 2. Both Comp Ex 1
and
Comp Ex 2 evidence an R-value drop over the six month period.
The combined data of Tables 1 and 2 show that, or balance, the foam
laminate boards of Ex 3-6 outperform those of Comp Ex 1 and 2. Similar results
are
expected by varying one or more of the materials and parameters presented in
the
Example. The above disclosure provides simple teachings of possible
variations.
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