Note: Descriptions are shown in the official language in which they were submitted.
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HIGH TEMPERATURE EXTERIOR BUILDING PRODUCTS
TECHNICAL FIELD
[0001] The invention relates generally to siding, trim, decking, fencing,
roofing and
other construction materials suitable for higher temperature applications than
standard
PVC applications.
BACKGROUND
[0002] Polyvinyl chloride (PVC), also known as vinyl, has become common in use
as house siding, trim, decking and fencing. Because of its low cost and ease
of
installation, PVC has gained wide acceptance as a construction material.
However,
because of its inability to withstand higher temperatures, PVC siding is used
mainly in
cooler climates, such as the northern states of the U.S.A. The use of PVC is
sometimes
avoided in warmer climates, such as exist in the U.S. states of Florida and
Arizona.
[0003] Recently, another problem has been found with PVC siding in cooler
climates. More residential structures are being built with irregular exterior
walls and
closer to adjacent structures. This has led to structures having a problem
with reflective
heat causing the siding and trim to distort from the heat. The excess heat is
generated as
a result of the sun's rays shining on a window and being reflected to an
adjacent wall of
the same structure or a neighboring structure.
[0004] Also, PVC is normally sold in white or light pastel colors for
construction
applications. Dark colors, such as red, black, brown and the like absorb more
energy
from the sun and cause the temperature of the material to exceed the useable
temperature
of PVC. Consumers and builders would like the option of using dark colors for
some
structures.
[0005] Construction materials comprising PVC may benefit from improvements.
ASPECTS OF EXEMPLARY EMBODIMENTS
[0006] An exemplary embodiment includes an article suitable for outdoor
construction applications that comprises an inner layer comprising a
chlorinated
polyvinyl chloride (CPVC) composition; an outer layer comprising a CPVC
composition; and an intermediate layer sandwich between the inner and outer
layers. An
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additional weather resistant cap layer may be included over the article outer
layer. The
intermediate layer comprises a PVC, or blended PVC composition. Other aspects
of
exemplary embodiments will be made apparent in the following Detailed
Description of
Exemplary Embodiments and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The foregoing summary, as well as the following detailed description of
exemplary embodiments, will be better understood when read in conjunction with
the
appended drawings. For the purpose of illustration, there is shown in the
drawings
certain exemplary embodiments. It should be understood, however, that the
invention is
not limited to the precise arrangements and instrumentalities shown in the
drawings or
described herein.
[0008] Fig. 1 is a perspective view end portions of a siding substrate
according to a
first embodiment;
[0009] Fig. 2 is a sectional view of the siding substrate without the
insulating
material taken along line 2-2 of Fig. 1;
[0010] Fig. 3 is a sectional view similar to that of Fig. 2 of a siding
substrate
according to a second embodiment;
[0011] Fig. 4 a sectional view similar to that of Fig. 2 of a siding substrate
according
to a third embodiment; and
[0012] Fig. 5A-C are graphs showing the results of an Oven Sag Test for a
sample of
the siding substrate of the first embodiment and samples of other sidings.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0013] The articles of some exemplary embodiments are comprised of rigid
thermoplastic materials with high heat distortion temperatures. Chlorinated
polyvinyl
chloride (CPVC) compositions may be used to make the articles by using an
extrusion
process.
[0014] A first exemplary embodiment comprises siding 10 used for buildings
such as
residential buildings and is depicted in Figs. 1 and 2. As best seen in Fig 2,
the siding 10
comprises an inner layer 12 comprising a CPVC composition; an outer layer 14
comprising a CPVC composition; and an intermediate layer 16 sandwiched between
the
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inner and outer layers 12, 14. The intermediate layer 16 of the exemplary
embodiment
comprises a polyvinyl chloride (PVC) composition. The exemplary CPVC material
of
the siding ranges from 9 to 75 wt. %, preferably 12 to 48 wt. %, and most
preferred from
16 to 24 wt. % of the total weight of the CPVC inner and outer layers and the
PVC
intermediate layer. In one embodiment, the material of siding 10 of this
embodiment
contains about 16 wt. % CPVC and in another embodiment the material of siding
10
contains about 24 wt. % CPVC. The exemplary siding 10 also includes slots 18
formed
at a hem 20 of the siding 10 that are used for hanging the siding. The siding
may include
an optional strip 28 for interlocking with a subsequent piece of siding (such
as 10 is
shown). The siding may also have an insulating member 22 such as foam adhered
to the
inner layer 12 by adhesive material between the insulating member 22 and the
innermost
layer 12, and/or a weather resistant cap layer 15 on top of the outer layer
14.
[0015] The CPVC compositions contain CPVC polymer (resin) along with various
additives, which are described below. The CPVC resin constitutes at least 50%
by
weight of the CPVC composition as these are rigid compositions. CPVC
compositions
are available commercially worldwide from a variety of sources, including
Lubrizol
Advanced Materials, Inc. of Cleveland, Ohio U.S.A.
[0016] CPVC for use in exemplary embodiments may be prepared by the post-
chlorination of suspension or mass polymerized PVC. Suspension polymerization
techniques may be of the type described in the Encyclopedia of PVC, pp. 76-85,
published by Marcel Decker, Inc. (1976), for example.
[0017] CPVC is obtained by chlorinating homopolymers or copolymers containing
less than 50% by weight of one or more copolymerizable comonomers. Suitable
comonomers for vinyl chloride include acrylic and methacrylic acids; esters of
acrylic
and methacrylic acid, wherein the ester portion has from 1 to 12 carbon atoms,
for
example, methyl-, ethyl-, butyl-, ethylhexyl acrylates and the like; methyl-,
ethyl-, butyl
methacrylates and the like; hydroxyalkyl esters of acrylic and methacrylic
acid, for
example, hydroxymethyl acrylate, hydroxyethyl acrylate, hydroxyethyl
methacrylate and
the like; glycidyl esters of acrylic and methacrylic acid, for example,
glycidyl acrylate,
glycidyl methacrylate and the like; alpha, beta-unsaturated dicarboxylic acids
and their
anhydrides, for example, maleic acid, fumaric acid, itaconic acid and acid
anhydrides of
these, and the like; acrylamide and methacrylamide; acrylonitrile and
methacrylonitrile;
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maleimides, for example, N-cyclohexyl maleimide; olefin, for example,
ethylene,
propylene, isobutylene, hexene, and the like; vinylidene halide, for example,
vinylidene
chloride; vinyl ester, for example vinyl acetate; vinyl ether, for example
methyl vinyl
ether, ally' glycidyl ether, n-butyl vinyl ether and the like; crosslinking
monomers, for
example, diallyl phthalate, ethylene glycol dimethacrylate, methylene bis-
acrylamide,
tracrylyl triazine, divinyl ether, ally' silanes and the like; and including
mixtures of any
of the above comonomers. Comonomers as well as crosslinking comonomers are
preferably absent. That is, preferred are homopolymers and uncrosslinked CPVC
polymers.
[0018] The molecular weight as measured by I.V. of precursor polyvinyl
chloride for
the CPVC polymer will range from about 0.4 to about 1.6, preferably 0.5 to 1.2
and most
preferably from about 0.7 to 1.0 I.V. The inherent viscosity is a
representative measure
of the molecular weight of a polymer and is obtained in accordance with ASTM
procedure No. D-1243-66. The choice of molecular weight is made by considering
the
shape and intricacy of the profile, the processing conditions and the physical
property
balance desired. If the molecular weight is too low, there may be insufficient
melt
strength and the dimensional stability of the hot extrudate will suffer, and
if the
molecular weight is too high, the compound may not be processable under the
desired
conditions. Acceptable results are obtained under a variety of conditions and
cross-
sectional shapes using an I.V. of the PVC precursor of about 0.85 to 0.95.
[0019] Chlorination of PVC can be carried out to obtain a chlorinated base
polymer
having higher than 57 percent by weight chlorine up to about 74 percent by
weight based
upon the total weight of the polymer. However, in practice, the use of a major
amount of
CPVC having a chlorine content of greater than 65% weight and up to 74% is
preferred,
and more preferably from 66% to about 70% chlorine.
[0020] The preferred method of post-chlorination is by the aqueous suspension
chlorination method. There are considerations relative to this method wherein
the
preferred mode of chlorination employs a relatively concentrated aqueous
suspension of
the precursor PVC. The most preferred method results in a CPVC resin having a
density
which does not deviate more than about 20 percent from the mean density, and a
surface
area which does not deviate more than 30 percent from the mean surface area is
more
desirable. A concentration of about 15 to about 35 weight percent of solids in
the
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suspension is preferred. Generally, a concentration of the suspension higher
than the
specified range results in less uniform chlorinated product, while
concentrations below
15 percent yield uniform product, but are not as economical. By "aqueous
suspension"
of PVC base polymer, we refer to a slurry-like mixture of base polymer
macrogranules
suspended in water. This process is particularly directed to a batch process.
[0021] It is desired that oxygen be removed from the aqueous suspension before
chlorination is initiated. This may be assisted with agitation. Heating as may
be
required is preferably done after C12 is sparged into suspension from a liquid
C12 cylinder
until the pressure in the reactor reaches about 25 psig, at which point the
suspension is
saturated with C12. It is preferred that this pressure be somewhat higher,
that is, in the
range from about 35 psig to about 100 psig, to get the optimum results, though
a pressure
as low as 10 psig and higher than 100 psig may be employed. The amount of C12
charged to the reactor is determined by weight loss in the C12 cylinder. The
reactor is
preferably brought up to a "soak" temperature in the range from about 60 C. to
about
75 C at which soak temperature the suspension is maintained under agitation
for a soak
period in the range from about 1 minute to about 45 minutes. Excessive
pressure
adversely affects the porosity of the macrogranules to the detriment of the
stability of the
chlorinated product.
[0022] It is desirable to complete the chlorination reaction under photo-
illumination,
preferably with ultraviolet light, or the desired conversion of base polymer
to chlorinated
base polymer product may not occur. Chlorination proceeds at a rate which
depends
upon the pressure and temperature within the reactor, higher rates being
favored at higher
temperature and pressure. It is most preferred to adjust the soak temperature,
the mass of
resin, and the level of photo-illumination so that the temperature is "ramped"
by the heat
of reaction until it levels off at a finishing temperature of about 100 C.
After
chlorination has proceeded to the desired degree, the suspension is preferably
not cooled
but dumped to be centrifuged and the chlorinated polymer freed from the
aqueous phase,
after which HC1 is removed from the product, preferably by neutralizing with
an aqueous
solution of an alkali metal hydroxide. The product is then washed with water
to free the
chlorinated polymer of residual alkali, and dried, except that the
temperatures at which
the operations are carried out may be in the range from about 60 C to about
100 C,
which may be somewhat higher than conventionally used.
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[0023] The rigid CPVC compositions contain various other ingredients, in
addition
to the CPVC polymer, to enhance processing and performance of the articles.
Ingredients such as heat stabilizers, impact modifiers, processing lubricants,
antioxidants,
antistats, processing aids, fillers, fibers and coloring pigments can be used
in the CPVC
compositions of exemplary embodiments. A desirable additive in some
embodiments is
chlorinated polyethylene.
[0024] The chlorinated polyethylene (CPE), when used in the CPVC compositions
of
the multi-layer article, has a specific gravity of from about 1.13 to 1.4,
preferably about
1.16, a residual crystallinity of from about 0 to about 25%, preferably 0 to
10%, and a
chlorine content from about 25% to about 45%, preferably 35% to 44%. The
chlorination can be either homogeneous or heterogeneous preferably to a small
extent.
Surface appearance of extrudates depended on CPE molecular weight and
polydispersity
as measured by gel permeation chromatography and on the extrusion conditions
used.
Chlorination methods for CPE include aqueous suspension, solution, or gas
phase
methods, with the preferred method by way of suspension chlorination. CPE is
commercially available from numerous sources such as Dow Chemical Inc. When
CPE
is used, the amount of CPE in the CPVC compositions present ranges from about
10 to
about 30 parts per 100 parts by weight (phr), preferably from about 12 to
about to 25 phr,
still more preferred are levels from 15 to 25 phr of CPVC resin. The
particular
combination of CPVC and CPE in exemplary aspects will be described below.
[0025] The core/shell type impact modifiers can be present in the CPVC
compositions. These include acrylonitrile butadiene styrene terpolymers (ABS),
methacrylate, acrylonitrile, butadiene, styrene (MABS) polymers and
methacrylate
butadiene styrene polymer (MBS). Other impact modifiers are disclosed in
Plastics
Compounding, November/December, 1983: "Update: Impact Modifiers for Rigid
PVC,"
by Mary C. McMurrer. Various commercial MBS grades include Paraloid0 KM-653,
BTA-733 from Rohm and Haas, or Kanegafuchi Inc. B-56 and B-22; Commercial
polyacrylate impact modifiers include KM -323B, and KM -330, from Rohm and
Haas, Inc.; ABS grades are commercially available from GE Plastics, Inc, for
example,
Blendex0 338.
[0026] Thermal stabilizers are employed in the compounds herein and can be
selected from various organic compounds. Suitable tin stabilizers include tin
salts of
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monocarboxylic acids such as stannous maleate. Examples of tin stabilizers
include
without limitation: alkylstannoic acids, bis(dialkyltin alkyl
carboxylate)maleates,
dialkyltin bis(alkylmaleates), dialkyltin dicrotonates, dialkyltin diolates,
dialkyltin
laurates, dialkyltin oxides, dialkyltin stearates, alkylchlorotin
bis(alkylmercaptides),
alkylchlorotin bis (alkylmercaptopropionates), alkylthiostannoic acids,
alkyltin
tris(alkylmercaptides), alkyltin tris(alkylmercaptoacetates),
alkyltin
tris(alkylmercaptopropionates), bis [dialkyl(alkoxyc arb
onylmethylenethio)tin] sulfides,
butyltin oxide sulfides, dialkyltin bis(alkylmercaptides),
dialkyltin
bis(alkylmercaptoacetates), dialkyltin bis(alkylmercaptopropionates),
dialkyltin p-
mercaptoacetates, dialkyltin P-mercaptoacetates, dialkyltin P-
mercaptopropionates,
dialkyltin sulfides, dibutyltin bis(i-octyl maleate), dibutyltin bis(i-octyl
thioglycolate),
dibutyltin bisthiododecane, dibutyltin P-mercaptopropionate, dimethyltin bis(i-
octyl
thioglycolate), dioctyltin laurate, methyltin tris(i-octyl thioglycolate).
Examples of a
commercially available tin stabilizer are Mark 292 and Mark 1900 stabilizers
from
Chemtura Chemical and Thermolite 31 stabilizer from Arkema. Tin compounds are
generally used at from 1 to 5 phr (parts by weight per 100 parts by weight of
CPVC
resin), preferably about 2.0 to 4.0 phr.
[0027] Secondary stabilizers may be included, if desired, but are not
necessary.
Examples of secondary stabilizers include metal salt of phosphoric acid,
polyols,
epoxidized oils, and acid acceptors which are not detrimental to the base CPVC
resin
used. The secondary stabilizers can be used by themselves or in combinations
as
desired. Specific examples of metal salts of phosphoric acid include water-
soluble,
alkali metal phosphate salts, disodium hydrogen phosphate, orthophosphates
such as
mono-, di-, and tri-orthophosphates of said alkali metals, alkali metal
polyphosphates,
-tetrapolyphosphates and -metaphosphates and the like. Polyols such as sugar
alcohols,
and epoxides such as epoxidized soya oil can be used. Examples of possible
acid
acceptors include potassium citrate, aluminum magnesium hydroxyl carbonate
hydrate,
magnesium aluminum silicates and alkali metal alumino silicates. Examples of
magnesium aluminum silicates are molecular sieves such as, for example,
Molsiy0
Adsorbent Type 4A from UOP. Examples of alkali metal alumino silicates are
zeolites
such as CBV 10A Zeolite Na-Mordenite by Synthetic Products Co. The most
preferred
secondary stabilizer is disodium hydrogen phosphate (DSP) and is used by
treating the
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CPVC resin. Typical levels of secondary stabilizers can range from about 0.1
wt. parts
to about 7.0 wt. parts per 100 wt. parts CPVC polymer (phr).
[0028] In addition, commercially available antioxidants are used such as
phenolics,
BHT, BHA, various hindered phenols and various inhibitors like substituted
benzophenones.
[0029] Other auxiliary components are contemplated. Antistats may be used and
are
commercially available under the Glycolube0 trademark of Lonza Corp. Exemplary
lubricants are the various hydrocarbons, such as paraffins, paraffin oils, low
molecular
weight polyethylene, oxidized polyethylenes, fatty acids and their salts such
as stearic
acid and calcium stearate, fatty alcohols such as cetyl, stearyl, or octadecyl
alcohol;
metal soaps such as calcium or zinc salts of oleic acid; fatty amides of
organic acids such
as stearamide, ethylene-bis-stearamide; preferred fatty esters and partial
esters such as
butyl stearate, polyol esters such as glycerol monostearate, hexaglycerol
distearate; and
fatty ester waxes such as stearyl esters. The most preferred lubricant is
oxidized
polyethylene. Henkel Co. produces a variety of preferred fatty ester
formulations under
the Loxio10 mark. Combinations of internal and external lubricants may also be
used.
Lubrication of the CPVC polymer compounds may involve several lubricants
combined
in variations. The total amount of lubricant may vary in some embodiments
generally
from about 2 to 10 phr, preferably from 2 to about 6 phr.
[0030] Adjustment of melt viscosity can be achieved as well as increasing melt
strength by optionally employing commercial acrylic process aids such as those
from
Rohm and Haas under the Paraloid0 Trademark, for example, Paraloid0 K-120ND, K-
120N, and K-175.
[0031] Exemplary fillers for both the CPVC layer and PVC layer are optional
and
include clay, wollastonite, mica, barytes, calcium carbonate, talc and silica
including
precipitated silicas, silica gels, metallic silicates, pyrogenic or fumed
silicas and the like.
These have the general formulae: Si02, Mn(SiO3)x. The values of n and x can
vary with
the oxidation state of the metal associated with the SiO3 ion. The values n
and x are
usually integers from about 1 to about 4.
[0032] Preferred pigments are the various titanium dioxides (Ti02) and carbon
blacks which are commercially available. Preferred TiO2 types are coated or
uncoated,
ruffle titanium dioxide powder. An exemplary commercial grade is Ti-Pure R-
100
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from E.I. DuPont De Nemours and Co. Inc. (DuPont). If used, pigments such as
TiO2
are present in an amount ranging from 1 to 25 phr, more typically 3 to 15 phr,
and most
typically from 3 to about 8 phr. Optional coloring pigments can be used.
[0033] Coloring pigments are used to impart the desired color of the CPVC
composition. TiO2 is the normal pigment to give a white color and carbon black
is used
to give a black color. Blends of color pigments are often used to achieve a
color that is
other than black or white. For example, a blend of TiO2 and carbon black is
used to
obtain a grey color. Various other color pigments such as red, blue, green,
yellow and
brown are commercially available from companies such as Ferro and Clariant.
The color
pigments can be added to the composition as dry powders, liquid dispersions or
as a
concentrate in the form of a color masterbatch.
[0034] The CPVC compositions are prepared by compounding the ingredients
together. The method of compounding preferably used is high intensity methods
to
uniformly mix and fuse the components into a homogeneous compound such as with
a
Banbury/mill, followed by sheeting, slitting or extrusion into pellets, or
cubes. The
differences in process handling of CPVC compared with polyvinyl chloride-based
compounds relate mainly to the temperature and viscosity differences and care
must be
taken to avoid too much work and shear burning. In the preparation of
compounds, the
components can be combined and mixed with a Banbury and milled on a heated
roll mill.
The fused compound can be extruded and chopped into cubes. Alternatively, the
components can be combined in a compounding twin screw extruder. The compounds
are extruded into final form at conventional stock temperatures from about 175
C to
about 225 C. The components of the CPVC composition can also be blended
together in
powder form and the blended powder fed to an extruder.
[0035] The articles of exemplary embodiments can be of any color, but are
particularly useful in dark colors. Certain PVC articles, such as house
siding, are often
only available in white and light pastel colors. This is because the dark
colors, such as
black, red, dark brown and the like absorb more heat from the sun and distort
PVC
articles. PVC articles can be used in cooler climates in light colors (white
or pastel), but
are not generally used in warmer climates, such as southern and southwest U.S.
climates,
nor is PVC commonly used for house siding or the like in dark colors, even in
cooler
climates. Typically, only the outer layer of CPVC composition would need to be
colored
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as the inner layer is hidden in use and the intermediate layer of PVC is
hidden in siding
applications. However, for efficiencies in production, it may be advantageous
to use the
same CPVC composition for both the inner and outer layers.
[0036] It is customary to define color as a L value. L value is a scale of
from 0 to
100. The color black would represent an L value of 0 and the color white would
represent an L value of 100. When the term "dark colors" is used herein, it
means the
color has a L value of less than about 50, preferably less than about 40, and
more
preferably less than about 30.
[0037] The CPVC compositions of exemplary embodiments preferably have a high
heat distortion temperature (HDT) as measured by ASTM D-648. The HDT of
exemplary compositions is greater than about 180 F (about 82.2 C), greater
than 190 F
(about 87.8 C), desirably greater than 205 F (about 96.1 C), preferably
greater than
about 210 F (about 98.9 C), and more preferably greater than about 215 F
(about 101.7
C). HDT of the composition can be varied by the chlorine content of the CPVC
polymer. The higher the chlorine content, the higher the HDT. HDT of the CPVC
composition can also be affected by the various compounding ingredients.
Liquid or low
molecular weight ingredients such as plasticizers, process aids and lubricants
can lower
the HDT and thus are used in certain exemplary embodiments in small amounts.
The
particular HDT of the composition used to make the articles will generally be
selected
based on the service temperature the article will experience in use. For
example, an
article of a dark color will commonly benefit from a higher HDT than a light
color article
used in the same climate and application. Articles, such as siding and trim
for siding
commonly benefit from a higher HDT when they are subjected to reflective heat
as can
occur from windows in adjacent walls or adjacent structures.
[0038] To form the CPVC composition into various articles of exemplary
embodiments, the extrusion process may be used. The extruder is fed with the
composition in either powder, cube or pellet form. The composition is melt
processed
and forced through a die into the desired shape of the article. The extruder
characteristics applicable to melt processing of the CPVC compounds include:
Extruder
drive/gearbox capable of generating high torque at low rpm. Vacuum venting to
remove
volatile components, moisture and entrapped air. A barrel L/D of at least 16/1
for twin
screw; generally at least 20/1 for single screw. Temperature controllers able
to control
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within +/-5 F or preferably +/-2 F. Accurately controllable powder metering
screw for
powder compounds.
[0039] A ramped barrel temperature profile is advisable with a zone nearest
the
hopper set at 180 C and the zone nearest the die at about 195 C for 0.75 inch
(about
19.05 mm) diameter screw. There can be used calibrating blocks at the exit end
to assist
in proper dimension sizing as the hot profile is cooled. Air streams can be
used to
improve heat loss, and for more close tolerances, vacuum water sizing devices
can be
used. The extent to which one chooses to employ calibrator blocks and air or
water
sizing will depend on dimension tolerances for the particular profile shape,
the intended
output volume of any one profile article and the number of different profiles
made with a
particular production set.
[0040] The CPVC composition described above is the preferred composition for
making siding and siding trim components. For articles which are thicker,
other CPVC
compositions may be used and in some cases preferred. The CPVC composition
used
will vary depending on the requirements of the end use application. In some
embodiments, the CPVC composition may be a CPVC based blend with other high
heat
plastics, such as styrenics. In alternate embodiments, at least one of the
inner and outer
layers may comprise a composition of a high heat plastic, such as, styrenics,
for example,
styrene-acrylonitrile copolymers (SAN), methyl-styrene-acrylonitrile
copolymers
(AMSAN), or blends thereof The term "high heat plastics" as used herein refers
to
materials that can exceed 180 F in continuous operating temperature.
[0041] When the exemplary article is a house siding or siding trim, the CPVC
composition for each of the outer layer and inner layer may be extruded to a
thickness of
from about 2 to about 19 mils (about 0.05 to about 0.48 mm), preferably 3 to
10 mils
(about 0.08 to about 0.25 mm) and more preferably 4 to 6 mils (about 0.10 to
about 0.15
mm). The siding and trim thickness is typically about 30 to about 50 mils
(about 0.76 to
about 1.27 mm) and more typically 40 to 48 mils (about 1.02 to about 1.22 mm).
The
term "siding trim" as used herein has the customary industry meaning and
includes trim
pieces such as outside corners, inside corners, channels around windows and
doors, and
the like, used in conjunction with the installation of siding. The siding and
trim of some
embodiments can be thinner than PVC siding because the exemplary embodiments
are
able to withstand greater heat and are more resistant to deformations. The
siding and
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trim can be embossed to provide a wood grain surface for aesthetic appeal. The
siding
and trim of some embodiments may be applied horizontally or vertically on a
structure.
[0042] When articles of exemplary embodiments include decking and fencing, the
extrusion may be thicker than that for siding because of the structural
requirements.
Decking and fencing will typically have a thickness of greater than 0.05
(about 1.27mm)
and preferably greater than 0.1 inch (about 2.54 mm). Decking and fencing are
typically
extruded with a cross section in a substantially rectangular shape and can
have rounded
corners to aid in the extrusion process. The term "rectangular shape" as used
herein is
intended to include rectangle shapes which have rounded corners. The
rectangular shape
can be hollow inside to save weight or can have reinforcing webs to add
strength and
rigidity. The extruded decking or fencing boards can also be filled with foam
to add
rigidity. Decking boards can also be embossed with a non-skid surface to
provide more
traction when wet. Decking materials may include the floor of the deck as well
as
supporting posts and rails, which can all be made from the exemplary CPVC
compositions. Fencing may include the fence boards or rails as well as the
posts. The
decking and fencing articles of exemplary embodiments eliminate the need for
painting
or staining as well as the need to use treated lumber and the environmental
and health
risks associated with the use of pressure treated lumber.
[0043] As previously mentioned, exemplary embodiments including siding and
trim
may have an insulating layer 22. The insulating layer 22 may include a layer
of
polystyrene foam but could be other insulating materials, such as polyurethane
foam.
The insulating layer 22 is preferably bonded to the CPVC layer with a suitable
adhesive
24 as illustrated in Fig. 1. A suitable adhesive for bonding CPVC to
polystyrene foam is
a moisture cured urethane, such as manufactured by Ashland Chemical Company of
Columbus, Ohio U.S.A. and known as ISOGRIPO 3030D. Alternatively, heat and
pressure sensitive adhesives can be used as well as latex based adhesives.
Preferably, the
adhesive remains flexible during use of the article.
[0044] The use of an insulating layer 22, such as foam, gives the siding and
trim
insulating properties to conserve energy. An insulating layer may also be used
to make
the siding or trim more rigid. Increased rigidity allows the CPVC layer to be
thinner and
aids in the installation of the articles to a structure. The siding and trim
are attached to a
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structure by conventional means such as nails, screws, staples, adhesives or
other
fasteners.
[0045] To produce exemplary articles having an insulating layer 22, the CPVC
composition may be extruded as described above. The insulating layer is formed
to the
desired size. The adhesive 24 is applied to the insulating layer or the CPVC
extruded
profile layer. The adhesive can be applied by roll coating, stitching,
extruding, spraying
or curtain coating. The adhesive can also be applied in the form of beads
which cover
only a portion of the CPVC layer. The extruded CPVC is applied to the
insulating layer
22 with the adhesive between the layers to form the article. The articles may
be made in
conventional lengths, such as 10 or 20 feet (about 3.05 or 6.1 m), to
facilitate storage and
transport to a job site.
[0046] The intermediate layer 16 of PVC can be made from commercially
available
PVC compositions, including recycled material. The PVC compositions are
available
from several manufacturers, such as ShinTech and PolyOne. Preferably, a PVC
composition used is one designed for siding applications. The PVC compositions
designed for siding applications use the same PVC resin as described above for
the PVC
precursor resin used to make the CPVC resin. Also, similar additives, such as
heat
stabilizers, impact modifiers, flow aids, lubricants and the like, can be used
as described
above for CPVC. The PVC compositions can be made the same way as the CPVC
compositions described above, except that PVC has a slightly lower processing
temperature, usually about 10-30 F. The % of the CPVC layers in the composite
siding
herein are expressed in weight percent. This is slightly different from
thickness percent,
as CPVC compositions normally have a higher specific gravity than PVC, usually
about
to 20% higher. If the PVC layer contains a large amount of heavy fillers, such
as
calcium carbonate or talc, it may have a higher specific gravity than the CPVC
layers, as
is well understood by those skilled in the art.
[0047] Embodiments that comprise siding 10 can be made in conventional widths
such as from 4 to 10 inches (about 10.16 cm to about 25.4 cm) or can be made
in thinner
or wider widths. The addition of an insulating layer to provide added rigidity
may allow
the siding to be made wider than conventional siding, if desired. Wider widths
can
reduce labor in the installation phase of construction. Widths as wide as 12,
18, 24, 36 or
48 inches (30.48, 45.72, 60.96, 91.44, or 121.92 cm) can be made with the
insulating
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layer 22 capped with CPVC. Siding trim pieces may also be made in standard
widths, or
wider or narrower in some embodiments.
[0048] The CPVC layer on the insulated siding and trim will preferably be from
about 2 to about 19 mils (about 0.05 to about 0.48 mm), preferably 3 to 10
mils (about
0.08 to about 0.25 mm) and more preferably 4 to 6 mils (about 0.10 to about
0.15 mm)
thick. The insulating layer is preferably a thickness of from about 0.1 to
about 2.0 inches
(about 0.254 to about 5.08 cm). PCT Patent Application WO 99/22092 describes a
PVC
siding product with a foam backing and U.S. Pat. No. 5,542,222 describes a
corner post
of PVC with a foam backing. The CPVC siding and siding trim components of this
invention are made similar to those described in the two disclosures above
with the
exception that the PVC layer is replaced with two CPVC layers (inner and outer
layers)
and a PVC intermediate layer. The outer CPVC layer or all three layers can be
in dark
colors. U.S. Pat. No. 5,542,222 and PCT Patent Application WO 99/22092 are
hereby
incorporated in their entirety in this disclosure.
[0049] Cap layer(s) can also be applied to the CPVC outer layer to increase
weather
resistance. One or more cap layers can be used. For example, a thin cap layer
of PVC
can be applied to the CPVC layer. In place of a PVC containing cap layer, a
cap layer of
ASA (acrylonitrile-styrene-acrylate) can be used. The PVC or ASA cap layer may
be
about 3 to 10 mils (about 0.08 to about 0.25 mm) thick and can be co-extruded
with the
CPVC layer. Since the cap layer has a lower HDT than the CPVC layer, the cap
layer is
preferably thinner than the CPVC layer. In some embodiments, a further cap
layer of a
composition containing a fluoropolymer can be applied to the first cap layer
or can be
applied directly to the CPVC layer. The fluoropolymer cap layer may be about 1
mil to
about 2 mils (about 0.03 to about 0.05mm) thick. The fluoropolymer cap layer
can be
pre-prepared and laminated to the CPVC or first cap layer or can be co-
extruded directly
onto the CPVC or first cap layer. The fluoropolymer containing cap layer may
also
contain a substantial amount of acrylic polymer in order to gain adhesion to
the CPVC or
first cap layer. A fluoropolymer containing cap layer and the ASA cap layer
may have
better weathering properties than the CPVC or PVC layer.
[0050] Fig. 3 shows a second exemplary embodiment. Similar reference numbers
will be used for elements that are common with the first embodiment. This
siding 100
comprises an inner layer 12 comprising a CPVC composition; an outer layer 14
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comprising a CPVC composition; and an intermediate layer 160 sandwiched
between the
inner and outer layers 12, 14. This intermediate layer 160 comprises a semi-
rigid
material such as fiber cement composition. An adhesive layer (not shown) may
be used
between the intermediate layer 160 and the inner layer 12 and between the
intermediate
layer 160 and the outer layer 14.
[0051] Fig. 4 shows a third exemplary embodiment. Similar reference numbers
will
be used for elements that are common with the first embodiment. This siding
200
comprises an inner layer 12 comprising a CPVC composition; an outer layer 14
comprising a CPVC composition; and an intermediate layer 260 sandwiched
between the
inner and outer layers. The intermediate layer comprises a semi-rigid material
such as
PVC foam or CPVC foam.
EXAMPLE:
[0052] Tests were performed on composite plaques (representing siding) of the
exemplary embodiment and two other multi-layer (comparative) composite
products.
To form the composite plaques, three layer samples are put into a press cavity
plate for
thickness control. The press is set at about 380 F (about 193.3 C) with 1000
psi (about
6.89 MPa) low pressure for 6 minutes. The pressure is raised to 54 tons and
held for 3
minutes. The obtained composite is then cooled under pressure. One of the
comparative
composite plaque products comprised a layer of PVC with only one layer of
CPVC. The
weight percentage of CPVC content in this comparative product was 24%. The
other
comparative composite plaque product comprised an inner layer comprising a PVC
composition; an outer layer comprising a PVC composition; and an intermediate
layer
sandwich between the inner and outer layers. The intermediate layer comprised
a CPVC
composition. The weight percentage of CPVC content in this product was 60%.
Samples of 0.125 inch (about 3.18 mm) thick for each plaque to be tested were
taken.
[0053] One test was done using composite plaques comparing the Oven Sag at 180
F
(about 82.2 C), 200 F (about 93.3 C), and 230 F (about 110 C) of the
composite of the
first embodiment with the two comparative above-mentioned other multi-layer
composite siding products. The oven sag test does not use an actual sample of
siding,
but rather uses a plaque made up of layers of materials which would be used to
make a
siding product. The oven sag test correlates well with the actual siding
product. The
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oven sag test looks at the sag of a sample bar under gravity load. One end of
the bar is
clamped while the other end is free to sag. By employing a range of
temperatures, the
temperature at which gross sag takes place can be found. Samples of 0.125
inches (about
3.18mm) thick plaques for each composite to be tested were taken with a sag
arm length
set at 3 1/4 inches length (82.55 mm). The percent content of CPVC was varied
for each
composite product.
[0054] The results of the test for the two layer PVC/CPVC composite siding
product
with the CPVC layer on the bottom is shown in Fig. 5A. As seen in Fig. 5A, the
two
layer PVC/CPVC composite siding product with the CPVC layer on the bottom
significantly improved sag resistance compared to the rigid PVC. As the CPVC
content
increased, the sag decreased and the sag resistance increased.
[0055] The results of the test for the three layer PVC/CPVC/PVC composite
plaque
product is show in Fig. 5B. This composite did not show bending after
processing due to
symmetry of the layers.
[0056] The results of the test for the three layer CPVC/PVC/CPVC composite
plaque
product of the exemplary embodiment is shown in Fig. 5C. This composite
product
performed the best of the three products tested in reducing sag at elevated
temperatures
even when used at low concentrations of CPVC. For example, with a CPVC content
of
16% weight, this sample deflected less than 5 mm when the Oven Sag Test was
performed on it at 180 F (about 82.2 C), 200 F (about 93.3 C), and 230 F
(about 110
C). Hence, from the standpoint of sag resistance/stiffness retention at 180 F
temperature, the CPVC content can be as low as 16-24% weight. This low
percentage of
CPVC reduced the costs of the product and thus, made it the most economical
choice
among the three siding products tested. Also, the symmetrical placement of the
layers
prevents bending or distortion of the composite samples after processing and
produces
the flattest specimens.
[0057] In the foregoing description, certain terms have been used for brevity,
clarity
and understanding, however, no unnecessary limitations are to be implied
therefrom,
because such terms are used for descriptive purposes and are intended to be
broadly
construed. Moreover, the descriptions and illustrations herein are by way of
examples
and the invention is not limited to the exact details shown and described.
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100581 In the following claims, any feature described as a means for
performing a
function shall be construed as encompassing any means known to those skilled
in the art
to be capable of performing the recited function, and shall not be limited to
the features
and structures shown herein or mere equivalents thereof The description of the
exemplary embodiment included in the Abstract included herewith shall not be
deemed
to limit the invention to features described therein.
[0059] Having described the features, discoveries and principles of the
invention, the
manner in which it is constructed and operated, and the advantages and useful
results
attained; the new and useful structures, devices, elements, arrangements,
parts,
combinations, systems, equipment, operations, methods and relationships are
set forth in
the appended claims.
