Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Ln~IOPLASTIC BLEND MATERIAL FOR
CAPPING OR COATING COMPOSITE
Field of the Invention
The invention relates to materials used for the
fabrication of layered profiles or capped structural
members used in residential and commercial architecture
and preferably in the manufacture of windows and doors.
More particularly, the invention relates to an improved
bilayer or multilayer structural member that can be used
as a direct replacement for wood and metal components
having superior weathering, aging and structural
properties. The layered structural members of the
invention can comprise sized member replacement or
structural components of complex functional shapes such
as window and door rails, jambs, styles, sills, tracks,
stop sash and trim and elements such as grid cove, bead
quarter round, etc.
Backqround of the Invention
Conventional window and door manufacturers utilize
structural members made commonly from hard and soft wood
members, metal components, typically aluminum, and
extruded thermoplastic materials. Residential window
and door components are often manufactured from a number
of specially shaped, milled wood products that are
assembled with glass sheets to form typically double
hung or casement windows and sliding door units. Some
units are made from extruded polyvinyl chloride (vinyl)
thermoplastic materials in preferred shapes. Such wood
or vinyl window or door units are typically structurally
sound and can be adapted for use in certain
installations. However, such materials require
maintenance and can have environmental degradation
problems caused by insect attack or microbial attack on
wood components and aging or environmental degradation
when exposed to sunlight, heat, cold, freeze-thaw cycle
and the natural environment. Metal windows and doors
have been introduced into the market place, however,
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such units made from extruded aluminum parts are often
energy inefficient and transfer substantial quantities
of heat from a heated exterior into a cold environment.
Extruded thermoplastic materials have been used in the
manufacture of window and door components. Typically
sealed edging grill and coatings have been manufactured
from thermoplastic material. Thermoplastic polyvinyl
chloride materials have been combined with wooden
structural members in the manufacture of PERMASHIELD
windows manufactured by Andersen Corporation for many
years. The technology performing the PERMASHIELD vinyl
coated wooden window members is disclosed in Zanini,
U.S. Patent Nos. 2,926,729 and 3,432,883. In the
manufacture of PERMASHIELD brand windows, a polyvinyl
chloride envelope or coating is extruded around the
wooden member as it passes through an extrusion head or
dye. Such coated members are commonly used as
structural components in forming the window frame work,
double hung or casement units.
Polyvinyl chloride has been a successful component
in the manufacture of residential and commercial window
and door units for many years. Polyvinyl chloride has
always been considered to be relatively stable in a
natural environment having acceptable resistance to
weather including sunlight, rain, snow, freeze-thaw
cycles and other aspects of the change in seasons. The
purchasers of window and door units in both residential
and commercial real estate are continuing to demand
increased performance when compared to past
achievements. One area highlighted for improvement in
window and door manufacturer is the weatherability of
extruded thermoplastic profiles. Any improvement in the
resistance of the thermoplastic profile to the harsh
effects of strong sun, rain, snow, wind, freeze-thaw
cycles and other environmental conditions will be a
welcome addition to the performance of known structural
units. Polyvinyl chloride polymer compositions used in
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such structural members have been known for many years
to contain pigments and other stabilizers that render
the polyvinyl chloride resistant to the undesirable
impact of weather. These pigments and other stabilizing
additives have been very successful in producing a
quality polyvinyl chloride product. An increase in the
properties of polyvinyl chloride is an important goal of
thermoplastic research and development.
Recently, Hartley et al., U.S. Patent No. 5,284,710
has disclosed an improved thermoplastic material. The
thermoplastic comprises a first layer comprising a
mixture of an acrylic polymeric composition and a
fluoropolymer polymeric composition and an inorganic
pigment which is used to coat a second layer on a first
member comprising a thermoplastic material. Hartley et
al. disclose that the acrylic\fluoropolymer blend
coating cooperates with the underlying thermoplastic
(preferably polyvinyl chloride) layer to reduce UV-light
induced polymer degradation when exposed to the
environment in an outdoor application. Hartley et al.
disclose that the acrylic\fluoropolymer composite
reduces loss in color, has improved stability, improved
flexibility or strength. In our testing of the Hartley
et al. material we have found the material to have
substantial advantages, however, the market place
appears to require improved performance when compared to
the Hartley et al. structures. Summers et al., U.S.
Patent No. 4,183,777 disclosed an improved weather
resistant product. The product comprises a substrate,
extrudate and a capstock containing a polyvinyl
chloride, a titanium dioxide pigment and a plasticizer.
Summers, U.S. Patent No. 4,247,506 teaches a method and
apparatus for processing extruded thermoplastic
materials showing the production of a siding profile
extruded from a thermoplastic such as PVC, CPVC or ABS.
Ravinovitch et al., U.S. Patent No. 4,424,292 disclose a
vinyl polymer composition containing a black infrared
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reflecting pigment to stabilize the polymer against the
undesirable aging properties of sunlight. The preferred
pigments comprise Ferro Black (Cr2O3-Fe2O3). Wallen, U.S.
Patent No. 5,030,676 teaches a W stabilized polyvinyl
chloride composition adapted for exterior use in house
siding and window profiles. The stabilized polyvinyl
chloride composition contains an organic impact
modifier, at least one thermal dehydrohalogenation
stabilizer and an ultraviolet stabilization system.
Bortnick et al., U.S. Patent No. 5,066,696 disclose
stabilizing polymers such as acrylates, styrenics,
polyvinyl chlorides and others with melamine type
hindered aromatic amine stabilizer compositions.
Trabert et al., U.S. Patent No. 5,318,737 teach a
thermoplastic composite having an underlying structural
extrudate with a capstock comprising an acrylic
thermoplastic. The capstock contains about 40 to 88 wt~
of an acrylic polymer having a molecular weight of at
least about 125,000 daltons and from about 12 to 60 wt~
of an acrylate-based impact modifier resin. The
modifier resin takes the form of discrete polymer
particles dispersed in the acrylic thermoplastic layer.
Grunewalder et al., U.S. Patent No. 5,322,899 teach a
layered extruded profile element. The profile contains
a capstock layer comprising a fluoropolymer/acrylic
polymer blend. The preferred polymer blend contains a
major proportion of the fluoropolymer and minor
proportions of the acrylic materials, pigments,
lubricants and other additive components. Kelch et al.,
U.S. Patent No. 5,356,705 teach a laminated weatherable
film capped siding material. The structure comprises a
weatherable styrene acrylonitrile copolymer comprising
an impact modifier comprising an olefinic elastomer or
an acrylic elastomer.
There is a large body of art relating to polyvinyl
chloride polymer compositions, polyvinyl-fluoropolymer
compositions and blended materials comprising a halo
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polymer and other additives and components. However, in
view of this large body of prior art, significantly
improved halo-polymer materials for environmentally
stable structures have, as yet, not been disclosed. A
substantial need exists in providing a thermoplastic
profile material having significantly improved
resistance to the degrading effects of the environment.
summarY of the Invention
We have found that significant improvements in
weatherability and aging resistance to the degrading or
discoloring effects of the environment can be achieved
by forming structural profiles from a core thermoplastic
polymer or composite thereof having a protective
exterior layer comprising a binary blend of a polyvinyl
chloride polymer composition with a polyvinylidene
fluoride polymer composition. The portions of the
profile exposed to the environment are manufactured with
the exterior layer blend material. The exterior layer
is surprisingly effective in protecting the profile as a
whole from the undesirable effects of weather and the
environment. We have found that the use of a major
portion of a polyvinyl chloride and an effective amount,
typically between about 1 and 45 wt~, of a
polyvinylidene fluoride polymer composition in
combination with other additives forms an exterior layer
that is dimensionally stable and superior to other
thermoplastic materials in resisting the degrading
effects of weather and the environment. The polymer
blend exterior layer bonds securely to the underlying
thermoplastic, has a well matched thermal expansion
coefficient, can be extruded at temperatures easily
achieved in the extrusion of the composite core and is
acceptable in terms of cost and other production
considerations. For the purpose of this application,
the term "polymer compositions" include homopolymers,
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copolymers, etc. and polymer materials containing
stabilizing additives, pigments, dye, lubricants,
reinforcing fibers, and other adjuvants.
Brief Diecueeion of the Drawin~s
Figure 1 is a graphical representation of the color
change of the cap stock material when exposed to xenon
arc radiation exposure. The color change over thirty
six months is shown. This test is an accelerated aging
test that should yield results that correlate with
actual exterior exposure results.
Figure 2 is a graphical representation of the color
stability of various poly vinyl chloride, poly
vinylidene chloride (PVC/PVDF) materials. The graph
shows a parabola having a focus between 70~ and 80% PVC
(20~ and 30~) PVDF showing substantially enhanced
stability.
Detailed Diecueeion of the Invention
The improved layered profile structural member of
the invention contain a core material comprising a
thermoplastic polymer or a thermoplastic-cellulosic
fiber composite having an exterior layer comprising a
polymer blend comprising a major proportion of polyvinyl
chloride and an effective stabilizing amount comprising
about 0.1 to 45 wt~ of a polyvinylidene fluoride
material. The exterior layer can comprise preferably
about 5 to 40 wt~ of the polyvinylidene fluoride, most
preferably about 20 to 35 wt~ for reasons of improved
environmental resistance, manufacturing ease and
manufacturing properties well matched between the
exterior layer and the extruded core material.
The exterior layer comprises a polyvinyl chloride.
Polyvinyl chloride (PVC) is a common industrial
thermoplastic. The polyvinyl chloride is compatible
with many additive stabilizers, lubricants, and other
polymers. PVC is known for use in rigid extruded
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articles and can be used to make clear sheet or opaque
pigmented materials. PVC is typically made by aqueous
suspension polymerization or bulk polymerization
techniques. Polyvinyl chloride polymer compositions
useful in the extrusions of the invention comprise
polymers having a molecular weight (Mn) of about 40,000
to 140,000, preferably about 7800 to 9800.
The core can be manufactured from a variety of
known thermoplastic extrudable polymeric materials.
Typically polymer materials that can be used in
structural units can be a core material. Known
thermoplastic resins that can be used in such an
application include polycarbonate acrylic polymers,
acrylamide polymers, poly(acrylonitrile-butadiene-
styrene) polymers, polyether ether ketone polymers,
polyacrylonitrile, polyethylene, polypropylene, and
other well known structural materials.
Polyvinylidene Fluoride Homo~olymer,
Copolymers and Polymeric Blends
The blend material obtains significantly improved
heat distortion, impact resistance, and other
mechanical properties including W and temperature
stability due to the inclusion of a fluoropolymer
composition. Such fluoropolymer compositions includethermoplastic, homopolymers or copolymers of vinyl
fluoride, vinylidene fluoride, tetrafluoroethylene,
pentafIuoropropylene, hexafluoropropylene, and
chlorotrifluoroethylene, as well as copolymers of these
fluorinated monomers with one or more other monomers
including any compatible copolymerized vinyl monomer
such as ethylene, propylene, vinyl chloride, vinylidene
chloride, acrylic acid, methylacrylic acid,
methylacrylate, methylmethacrylate, and other similar
acrylic monomers, etc. Further, mixtures of
fluoropolymers can also be used in the blend composition
if compatible. A preferred class of polyvinylidene
fluoride homopolymers and copolymers are sold under the
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trade name KYNAR~ sold by Elf Adochem North America,
Philadelphia, Pennsylvania. Similar materials are sold
by Kureha, Solvay Polymers, Asai Glass and ICI Advanced
Materials. Preferred polyvinylidene fluoride materials
are polyvinylidene fluoride homopolymers and a copolymer
of vinylidene fluoride with hexofluoropropylene.
Polyvinyl Chloride Homopolymer,
Copolymers and Polymeric Blends
Polyvinyl chloride is a common commodity
thermoplastic polymer. Vinyl chloride monomer is made
from a variety of different processes such as the
reaction of acetylene and hydrogen chloride and the
direct chlorination of ethylene. Polyvinyl chloride is
typically manufactured by the free radical
polymerization of vinyl chloride resulting in a useful
thermoplastic polymer. After polymerization, polyvinyl
chloride is commonly combined with thermal stabilizers,
lubricants, plasticizers, organic and inorganic
pigments, fillers, biocides, processing aids, smoke
suppressants, flame retardants and other commonly
available additive materials. Polyvinyl chloride can
also be combined with other vinyl monomers in the
manufacture of polyvinyl chloride copolymers. Such
copolymers can be linear copolymers, branched
copolymers, graft copolymers, random copolymers, regular
repeating copolymers, block copolymers, etc. Monomers
that can be combined with vinyl chloride to form vinyl
chloride copolymers include a acrylonitrile; alpha-
olefins such as ethylene, propylene, etc.; chlorinatedmonomers such as vinylidene dichloride, acrylate
monomers such as acrylic acid, methylacrylate,
methylmethacrylate, acrylamide, hydroxyethyl acrylate,
and others; styrenic monomers such as styrene,
alphamethyl styrene, vinyl toluene, etc.; vinyl acetate;
and other commonly available ethylenically unsaturated
monomer compositions.
Such monomers can be used in an amount of up to
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about 50 mol-~, the balance being vinyl chloride. Such
blends or polymer alloys can be useful in manufacturing
the pellet or linear extrudate of the invention. Such
blends typically comprise two miscible polymers blended
to form a uniform composition. Scientific and
commercial progress in the area of polymer blends has
lead to the realization that important physical property
improvements can be made not by developing new polymer
material but by forming polymer blends or blends. A
polymer blend at equilibrium comprises a mixture of two
amorphous polymers existing as a single phase of
intimately mixed segments of the two macro molecular
components. Miscible amorphous polymers form glasses
upon sufficient cooling and a homogeneous or miscible
polymer blend exhibits a single, composition dependent
glass transition temperature (Tg). Immiscible or non-
alloyed blend of polymers typically displays two or more
glass transition temperatures associated with immiscible
polymer phases. In the simplest cases, the properties
of polymer blends reflect a composition weighted average
of properties possessed by the components. In general,
however, the property dependence on composition varies
in a complex way with a particular property, the nature
of the components (glassy, rubbery or semi-crystalline),
the thermodynamic state of the blend, and its mechanical
state whether molecules and phases are oriented.
Polyvinyl chloride forms a number of known polymer
blends including, for example, polyvinyl
chloride/nitrile rubber; polyvinyl chloride and related
chlorinated copolymers and terpolymers of polyvinyl
chloride or vinylidine dichloride; polyvinyl
chloride/alphamethyl styrene-acrylonitrile copolymer
blends; polyvinyl chloride/polyethylene; polyvinyl
chloride/chlorinated polyethylene and others.
The primary requirement for the underlying
thermoplastic polymeric material is that it has
sufficient thermopiastic properties to permit the
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composition material or pellet to be extruded or
injection molded in a thermoplastic process forming the
rigid structural member. Polyvinyl chloride
homopolymers copolymers and polymer alloys are available
from a number of manufacturers including Geon, Vista,
Air Products, Occidental Chemicals, etc. Preferred
polymer materials include polyvinyl chloride homopolymer
having a molecular weight (M~) of about 90,000 + 50,000,
most preferably about 88,000 + 10,000, a CPVC polymer,
an ABS polymer, etc.
The blend material of the invention can contain
effective amounts, to obtain the benefits of known
additives, preferably ranging from about 0.5 to about 10
parts by weight per each 100 parts by weight of the
total blend composition of various compounding
components known in the art. Such components include
lubricants such as stearic acid, oxidized polyethylene,
polypropylene, paraffin wax, metallic salts of fatty
esters including mixtures, etc. Stabilizers for the
polymer materials include barium/cadmium/zinc compounds
and various organotins, for example, methyl, butyl,
ontyltin carboxylates, mercapto-carboxylates,
mercaptides, glycolates, thioglycolates, etc. Specific
examples include dibutyl-S-S'-bis(isooxyl mercapto
acetate), dibutyl tin dilaurate, with organotin di-
isooxyl thioglycolates being preferred. Secondary
stabilizers may include, for example, phosphates and
metal salts of phosphoric acid. Specific examples of
salts include water soluble alkaline metal phosphate
salts, disodium hydrogen phosphate, orthophosphate such
as mono, di and triorthophosphates of said alkaline
metals, alkaline metal polyphosphates,
tetrapolyphosphates, and similar condensed phosphate
species. In addition, antioxidants may also be
incorporated such as phenolics, BHT, BHA, various
inhibitors such as substituted benzothiazoles, etc. can
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be utilized to provide oxidation resistance, W
resistance, etc.
Various fillers, pigments and colorants can also be
used in effective amounts. Examples of fillers include
caesium carbonate clay silica, various silicates and
talc. Examples of various pigments include rutile
titanium dioxide, carbon black and the like.
Plasticizers may be included in any manner and amount
when required by the end use. Plasticizers are well
known in the art but are also set forth in "The
Technology of Plasticizers", Sears and Darby, John
Marley & Sons, New York, 1982, which are incorporated
herein by reference.
The PVC/PVDF blend can be prepared in high speed
powered mixing devices that can be operated at an
effective melt blending temperature. High speed power
mixing devices including a Banberry mixer extruder
equipment. Once compounded, the mixed blend can be
calendared, extruded, or injected, molded or processed
in any suitable thermoplastic melt processing means.
The polymers can also be mixed with various additives,
pigments, antioxidants, etc. in a high intensity mixer
such as a Hershel mixer and then processed on an
extruder into pellets or directly into a finished
article by way of compounding extruder. In general, any
conventional means of compounding melt processing,
extruding, injection molding, etc. can be used to
prepare the blend of the invention. The materials in
the invention can be used in melt process equipment to
form a variety of end use articles such as molded
sheets, trays, structural members, appliance parts,
cases, electric outlets, piping, automotive components,
electronic components, etc.
The exterior layer of the extruded profiles of the
invention can comprise a major proportion (greater than
50 wt~) of a polyvinyl chloride polymer composition.
The extruded material can also contain a minor
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proportion tless than 50 wt~) of a polyvinylidene
fluoride polymer composition in combination with
optional additives including heat stabilizers,
lubricants, UV absorbers, light stabilizers, pigments,
impact modifiers, processing aids and other known
additive materials. The exterior layer of the extruded
profile of the invention can contain an additive or
stabilizer that improves the resistance of the polymer
material through the undesirable effects of visible and
ultraviolet light. A variety of types of stabilizers
can be used including organic salts of barium, cadmium
and tin. Preferred salts are salts of carboxylic acids
including maleic acid, phthalic acid or other similar
organic carboxylic acids. Oxygen scavengers can be used
to prevent oxygen catalyzed dehydrohalengenation.
Ultraviolet light absorbers are useful in improving the
weatherability in light resistance of the exterior
layer. Preferred ultraviolet light absorbers are
derivatives of orthohydroxy benzophenone, orthohydroxy
phenyl salycilate or 2-(ortho-
hydroxyphenyl)benzotriazole.
Additives can also be used to prevent or suppress
thermal oxidative degradation. Both hindered phenols
and hindered aromatic amines, acting as labile hydrogen
donors, can inhibit thermal degradation of a variety of
polymer materials. Helpful materials that prevent
thermal degradation and thermal oxidation include alkyl
thiodipropionates, naphtholdisulfides, naphtholthioles,
mercaptobenzothiazoles, benzothiazine, tris(para-
nonylphenylphosphite), zinc dimethyldithiocarbamates,oxamides, oxanalides, benzotriazoles and others.
Thermoplastic materials are often formulated with
lubricants (also known as mold release agents) to
promote the ease of extrusion of the materials in
extrusion dies. Such lubricants control or eliminate
the tendency of the melt polymer to adhere to the
surface of the dye or mold. Lubricants are diverse in
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terms of physical and chemical properties. Typical
chemical classes include the long chain alkyl
derivatives such as synthetic waxes comprising fatty
esters, fatty acid, fatty acid methyl salts, fatty acid
amides, fatty acid amines and fatty alcohols. Other
natural products include petroleum waxes, vegetable
waxes, animal waxes, cellulose derivatives, and
polysaccharide. Synthetic polymer lubricants include
silicone polymer materials, fluorocarbons and low
molecular weight fluoropolymers including
polytetrafluoroethylene (Teflon), poly(fluoroacrylate),
polyfluoro-ethers and others. Fluorinated lubricant
compounds include fluorinated fatty acids and alcohols
such as perfluorolauric acid, perfluorostearic acid,
etc. Lastly, inorganic lubricants are known including
silicates, clays, silica, graphite and others.
The preferred extruded profile structural member of
the invention contains a structural core comprising a
polyvinyl chloride-cellulosic fiber composite. For the
purpose of this invention, the term "core" connotes any
shaped structural member including solid structural
members, hollow structural members, structural members
having a complex external shape, a variety of internal
components including support webs, screw anchors,
internal assembly components, etc. The core can also
contain external features such as screen supports,
hardware supports, decorative relief, or any other
internal or external feature or structure useful in the
manufacture of windows or doors. Such a core structure
can be covered with the external layer comprising the
PVC\PVDF material to preserve weatherability.
The core material is preferably made of a polyvinyl
chloride cellulosic fiber composite. The polyvinyl
chloride material used in the composite is recited
above.
Cellulosic fibers used in the manufacture of the
composite core of the invention can be obtained from a
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variety of ~ources of fiber. Virtually any fibrouQ
cellulo~ic material th~t can be converted into the
preferred particle size and aspect ratios required for
structural propertie~ can be used. However, a preferre~
fiber for use in the composites of the invent~on
comprise cellulosic wood fibers. The wood f~ber can be
derived from ~oft woods, evergreenQ, hard wood~, also
commonly known as broad leaf deciduouQ tree~. The wood
fiber can be made by abrading bulk wood ineo fibrouq
component~ or by u~ing the sawdust by-product of a wood
milling or cutting operations. Preferred wood fiber has
a regular reprod~cible shape and a~pect ratio. The
fibers are commonly about 0.1 to about 10 millimeters i~
length. The fibers al~o commonly have a minimum
thickne~s of about 0.1 millimeters and are preferably
between 0.01 and 3 millimeters in thickness. One
i~portant aspect of the fibcr3 of the invention i9
aspect ratio (ratio of lenyth or width) which is
typically greater than about 1.8. Preferably, the fiber
dimensions are 1 to 10 millimeters ln length, 0.1 to 3
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millimeters in thickness having an aspect ratio of about
2 to 7.
The raw cellulosic fiber is commonly screened or
otherwise classified to obtain a consistent fiber raw
material having reliable length thickness and aspect
ratio. The source of quality fiber with stable
dimensions can significantly increase the structural
properties as measured by Young's modulus and tensile
strength.
We have found that in the manufacture of the
composite materials of the invention that moisture
control in the cellulosic fiber is important. Water is
a natural component of all fiber sources and can range,
depending on season and local climate, from 5 to 45 wt~
water based on the total weight of a cellulosic source.
We have found that the wood fiber used in the composite
material should contain less than about 8~ water based
on the wood fiber. The preferred water content of the
extruded composite is as low as can be achieved by
drying the wood fiber at any point in the process. The
wood fiber can be dried prior to combination with the
thermoplastic, the thermoplastic after combination can
be dried prior to introduction into the extruder
material or the heated mass of thermoplastic and fiber
can be dried during shear processing or at any point in
the extrusion process. The material can be exposed to
vacuum or other processing conditions that can tend to
optimize water removal. Commonly, thermoplastic
composites used in the manufacture of the profiles in
the invention are typically preformed into pellet
materials. The preferred pellets for use in this
invention contain less than 8 wt~, moisture less than 5~
moisture and preferably less than 3.5 wt~ moisture. The
resulting extruded material can contain less moisture
than the pellet moisture if processed to minimize water
content.
Preferred blend of PVC and PVDF can be obtained in
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the form of powder chips or small pellets. The
materials can be dry blended with other ingredients
including W absorbers, lubricants, etc. and then
pelletized in commonly available single or twin
extruders at an appropriate temperature above the
melting point of the resin materials in order to
thoroughly mix the polymers and additive material into a
uniform melt composition. The melt can be extruded
through a dye forming spaghetti like strands or pellets
(the strands are cut into segments). The preferred
pellets are about 1-5 millimeters in diameter and about
1-10 millimeters long. The coextruded profiles of the
invention having an exterior layer comprising the PVC-
PVDF polymer allow layered on a polyvinyl chloride
composite material were manufactured by coextruding the
materials in twin screw equipment. The extruder was
equipped with a dye capable of forming the exterior
layer on the composite layer. The composite material
can be extruded by the twin screw or single screw
extruder at temperatures ranging from about 140C to
175C in a preferred profile for window or door
manufacture. The exterior layer can be formed by
coextruding onto the structural profile material derived
from the blend pellets described above. The twin screw
extruder for the PVC-PVDF material can be run at
temperatures from about 150C to provide the blend
material at extrusion rates similar to the profile
composite. The PVC-PVDF material is extruded through a
dye providing an exterior layer conforming in shape to
the composite material. The exterior layer typically
has a thickness of about 0.1 to 1.5 millimeters,
preferably 0.03 to 0.8 millimeters and covers any
portion of the extrudate exposed to the exterior
environment. For PVC covering layers the exterior layer
typically has a thickness of about 0.05 to 1.5
millimeters and covers any portion of the extrudate
exposed to the exterior environment. The exterior layer
2177412
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can cover a relatively small portion, 5-10~ of the
exterior surface area of the profile, or can entirely
cover 95-100~ of the exterior surface area. Any
intermediate surface area required for environmental
protection can be selected by the engineer. No adhesive
layer is used between the exterior layer and the
extruded profile. The appropriate shape of the laminate
is maintained by vacuum gauging and cooled in a water
bath to a controlled dimension. The extruded profile
can then be cut and assembled into window or door units
using conventional construction technology. It should
be clearly understood that the shape of the dye used in
the extrusion of the exterior layer and in the extrusion
of the profile layer, is to be selected by the engineer
for optimizing both the confirmation of the structural
member to its end use and to ensure that the exterior
layer covers portions of the profile requiring
protection from the undesirable effects of the
environment including ultraviolet light, degradation,
heat and cooling cycles, etc.
The bi- or multilayer extrudate of the invention
are typically made my coextrusion techniques including
biextrusion, cocollandering, triextrusion which may
incorporate an intermediate treatment adhesive or other
bonding layer.
Extrusion Capping
A lab scale twin screw extruder was used for the
base portion of the product and a single screw, lab
scale extruder was used for the capping. A PVC
Composite was used as the substrate material comprising
60 parts PVC and 40 parts wood fiber.
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Temperature Settings
Main Twin Screw Extruder
Barrel zone 1 180C
2 180C
Die zone 1 172C
2 172C
Screw oil 180C
Screw rpm 16.1
Feeder rpm 25
Single Screw Extruder - Kynar based materials
Barrel zone 1 180C
2 176C
Screw rpm 8
Single Screw Extruder - PVC only formula
sarrel zone 1 148C
2 154C
Screw rpm 8
Experimental
The following experiments and data were developed
to further illustrate the invention that is explained in
detail above. The following information illustrates the
25 typical production formulation of the preferred exterior
layer and the composition of the preferred core
material. The data shows the unique stability of the
material when exposed to accelerated aging testing. The
following 29
30 examples and data shown in the examples and table
contain a best mode.
2177412
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We investigated a variety of capping co-extruded
materials.
Kynar the Product
It is supplied in 2 forms:
1. cubes - these process well through an extruder,
without degrading, but do not readily accept
pigmentation. Kynar cannot be processed using
normal dispensing agents as they contaminate,
and ultimately destroy the surface finish.
2. powders - these do not flow and bridge badly but do
accept pigments.
solution - a 50/50 mix of powder and pellets are
used
to provide both pigment dispersion and the
necessary flow characteristics (products 2800
and 2801).
adhesion - P.V.D.F. (Kynar) on its own, does not
adhere to PVC very well and even less to PVC
composites. To lessen cost (for one thing)
and to improve adhesion, Elf Atochem
recommended the addition of Acrylic
(Plexiglas) to partially solve this but as was
later found - additional research into bonding
media was required.
Elf Atochem Formula
Kynar Flex 2800 series 61.6%
Acrylic - Plexiglas VS100 26.4
Pigment 12.0
100.0~
In processing this formula, we found several
problems:
1. The coating was very "tacky" to the touch and
was not vacuum sizable. It was later found that this
tackiness
2 1 774 1 2
-
23
persisted until the surface had cooled and hardened in
water.
2. Very poor adhesion was encountered with
average tensile force (to pull off) as low as 6 lbs.
(right angle pull force over 1.625" width).
Accelerated Weathering
The accelerated aging test is a well known testing
protocol involving exposing a polymer structural
material to a Xenon-arc device. This allows laboratory
controlled conditions of light, heat and moisture to
achieve accelerated degradation using radiation that is
more intense than natural solar radiation. The spectrum
produced by an artificial light source is extremely
important in assuring that results correlate to real-
time out door exposures. It can be demonstrated thatproperly filtered xenon lamps produce a spectral
distribution that approximates nature more closely than
other types of manufactured radiant sources. This is
the primary reason the xenon device is the unit of
choice over other alternatives such as Carbon arc
devices or Fluorescent devices.
The exposure was conducted according to the test
specification ASTM G26. The tests were conducted using
Heraeus XENOTEST 1200 with low wavelength W filter.
Test cycle is 102 minutes light followed by 18 minutes
light with water spray; 63+3C Black Panel Temperature
with 50+5~ Relative Humidity maintained during the
light-only phase. Source irradiance held at 100 W/m2
over the spectral range of 300 nm to 400 nm. With these
conditions samples dosage is 80 W/m2 for the spectral
range 300 nm to 385 nm. The normalized Southern Florida
W Irradiance (26South) is 280 MJ/m2 for the spectral
range 300 nm to 385 nm. (Quarterly Exposure, Heraeus
DSET Laboratories, Inc. Fall 1992 Florida News W
Equivalent Year). Each hour of test exposure results in
a dosage of 0.2884 MJ/m2.
Samples were rotated every 168 Hrs. Flat specimen
2 1 7741 2
-
24
nominally 200 mil thick were cut to a surface dimension
of 2.5" by 7" to properly fit the sample holder.
Chalk, color, gloss and visual data was collected
every 140 MJ/m2 dosage interval.
Tape Chalk evaluations are performed in accordance
with ASTM D4214-89, test method D.
Color measurements are performed on a HunterLab
Ultrascan, spectrocolorimeter with a 6" integrating
sphere reflectance specular excluded in accordance with
ASTM D2244-89 and ASTM E308-90 with a 10 observer and
lm; n~nt C. The specimen port is a circular and 1.25
inch in diameter with an 8 viewing angle and a beam
diameter of 1.00 inch. The reduction of data is
computed from the spectral data taken every lOnm over
the wavelength range from 375nm to 750nm.
Gloss measurements are performed in accordance with
ASTM D523-89 at an angle of 60 with a Byk Gardner
Micro-Tri-Gloss portable glossmeter.
Inspections are performed on all specimens as per
client instructions. Please refer to Appendix I of Test
Reports for applicable standards used.
General Appearance Rating Other Criteria Rating
10-As Rec'd 8-Good 4-Poor 10-As Rec'd 8-Slight 4-Considerable
9-Excellent 6-Fair 2-V.Poor 9-V.Slight 6-Moderate 2-Severe
In order to overcome the above problems a series of
modified formulas were developed.
21 77412
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K~nar/Acrylic Series - Ex. 1
Kynar 2800 25.0~
Kynar 2801 25.0%
Plexiglas VS100 50.0
TOTAL 100.0~
Pigment 12 phr
Elf Atochem SuPplied - Ex. 2
Kynar 2800 series 61.6
10 Plexiglas VS100 26.4%
Pigment 12.0~
100 . 0%
70~ Kynar/30~ Acrylic - Ex. 3
Kynar 2800 35.0
Kynar 2801 35.0
Plexiglas VS100 30.0
100 . Og~
Pigment 12 phr
Kynar/PVC Series - Ex. 4
Kynar 2800 35.0
Kynar 2801 35.0
PVC Geon 30.0
100.0~ resin =82.00
T634 3.0 phr 2.46
K120N 1.5 phr 1.23
D200 4.0 phr 3.28
AC165 0.3 phr 0.25
AC 629A 0.1 phr 0.80
Tinuvin 328 0.7 phr 0.57
Chimmasorb 944 0.3 phr 0.25
Pigment 12.0 phr 9.80
21 7741 2
-
26
Kynar/PVC - Ex. 5
PVC resin 70
Kynar 280130
100
T634 3.0 phr
K120N 1.5 phr
D200 4.0 phr
AC165 0.3 phr
AC629A 0.1 phr
Tinuvin 3280.7 phr
Chimmasorb 944 0.3 phr
Pigment 12.0 phr
Piqment System
TerratoneShepherd Black lG 33.67
Shepherd Brown 19 38.99
Shepherd Brown 10 5.38
Tiona RCL4 (TiO2) 19.83
Kroma Red RO5097 2.13
100.00
SandtoneTiona RCL4 (TiO2) 62.15
Shepherd Brown 19 11.19
Shepherd Brown 10 11.11
Shepherd Yellow 193 7.42
Shepherd Black lG 6.81
Chroma Red RO5079 0.59
100.00
2177412
White (138) Tiona RCL4 (TiO2) 98.07%
Shepherd Black lG 0.74%
Shepherd Yellow 193 0.74%
Shepherd Yellow 195 0.37%
Kroma Red RO5097 0.08%
100 . 00%
Please note that the use of TiO2 is not limited to
Tiona RCL4. The Dupont Product R102 (rutile) can be
used with minimal color or performance shift as can
Kronos 2071.
Method of Producing Pigments
Because of the problem of airborne contamination
all pigment blends were "tumbled" in an improvised jar
mill. This appeared sufficient to provide a
satisfactory product mix.
Method of Producing Capstock Material
All capstock blends were produced in the laboratory
Littleford high intensity mixer as follows:
1. Kynar/Acrylic Blends
All products added at one time and blended for
5 minutes only with pigment included.
2. Kynar PVC Blends
a) add PVC, Kynar and Stabilizer to mixer;
blend to 130F.
b) add all other additives except pigment;
blend to 140F.
c) add pigment and blend to 145F.
d) run mixture through a twin screw extruder
at temperature settings of 205C (zone
1); 195C (zone 2); 185C (zone 3); 180C
(adapter) and 185C (die).
~ . 2177412
28
e) product extruded was then ground in a
Cumberland grinder ready for the capping
portion of the trial.
ADHESION TESTING
HESIOMETER
Principles of Operation: The Hesiometer is capable
of evaluating intrinsic adhesion energy or practical
adhesion. A hyper-sharp, hardened blade cuts through a
coating to the multi-layer interface or the
coating/substrate interface. An interfacial split is
generated and projected forward of the blade cutting
region. The energy required to perpetuate this
interfacial splitting is a measure of adhesion.
Sample Preparation: All samples were cut to 7cm in
length and 4cm in width. This was done to ensure proper
fit in the machine. The submitted samples were also
mechanically modified by defining a 5mm wide test area
to eliminate edge effects. The modification was
accomplished through the use of an exacto knife. The
exacto knife was used to scribe parallel lines that
penetrate down to the substrate. The distance between
the parallel lines is the same as the width of the
hesiometer blade.
OPeration: The hesiometer applies an empirically
defined blade force, at an empirically defined angle,
perpendicular to the sample travel. The blade is
brought into contact with the sample until the applied
force stabilizes to the set value. The transverse or
cutting force is then measured as the sample moves
perpendicular to the applied force.
The cutting force increases as the blade begins
cutting through the coating. The cutting force levels
out when the blade reaches the coating/substrate
interface. A successful test has been completed when
the blade reaches the coating/substrate interface. The
transverse force curve, frictional force value, blade or
2177412
29
sample width, and the coating removal distance are then
recorded to the hesiometer software. The recorded
values are used to calculate the energy per unit area.
The energy per unit area is a measure of practical
adhesion.
Practical adhesion can be used to test samples of
the same type. The tested samples can then be evaluated
and compared to other samples of the same type using
group statistics. This type of testing can develop
guidelines for product quality analysis.
SPecific Test Conditions: A five millimeter wide
flexible blade was employed at a 20 and 25 degree angle.
The applied loads on the blade were lN to 3N. Sample
travel rate was five millimeters per minute in all
cases.
HESIOMETER
1. Romulus II Universal Tester
2. Hesiometer Module
3. Quattro-pro software
HESIOMETER
Table II shows the results of all the tested
samples. Included in the table is the mean, standard
deviation, and the minimum and maximum adhesion energy
values.
2177412
-
Table II. Hesiometer results for all submitted samples.
FO~ TION NFAN STD. DEV. MINIMUM MAXIM~M
3 70% Kynar N/A N/A N/A N/A
30% Acrylic
12 60% Kynar 732.25 138.73 602 901
40% Acrylic
9 60% Kynar 868.6 161.9 735 1142
40% Acrylic
6 70% Kynar 1003.2 515.31 379 1636
30% PVC
21 70% PVC 2511.3 742.12 1779 3437
30% Kynar
24 100% PVC 7427 700.02 6686 8077
HESIOMETER
According to table II, sample 03 appeared to have
had the poorest adhesion energy. It was observed that
when the sample was mechanically prepared for the
hesiometer testing, the coating would detach. Samples 9
and 12 also appear to have low adhesion energy. During
the testing of these samples, the coating would begin to
remove from the substrate at a relatively large distance
from the blade tip. This may be due to rigid
characteristic of the coating which could contribute to
the low adhesive strength of the material.
Sample 24 showed improved adhesive strength over
the previous samples. After the testing was completed
for these samples, it was observed that some of the
coating was left on the substrate. This suggests the
adhesive strength between the coating and the substrate
was good. The adhesive strength of sample 24 also
appeared to be good. During the testing of this sample,
the coating and the substrate were removed. This
prevented the adhesive strength of the coating from
being determined. Instead, the adhesive strength of the
substrate was recorded. However, this value is still of
217~412
-
31
importance since it represents the good adhesive
strength between the coating and the substrate.
HESIOMETER
The results of the hesiometer give the desired
information about the adhesion energy between the
coating and the substrate. According to the results, it
may be assumed that sample 24 has the strongest coating
adherence to the substrate.
The materials set forth above were tested for light
stability using Xenum-arc testing protocol and adhesion
testing. The results of the Xenum-arc light stability
testing are summarized in figures 1 and 2. The poorest
material, 100~ polyvinyl chloride, had substantial
deltaE color changes over the twenty-four month time
frame. The other formula had improved color changes.
However, of the other formulas, the 70~ PVC/30~ PVDF had
superior Xenum-arc exposure stability when compared to
the other materials.
The foregoing disclosure provides an explanation of
the compositions and properties of the extruded profile
manufactured from a composite core and an exterior
layer. Many alterations, variations and modifications
of the invention arising in the extruded profile
material can be made by substitution of equivalent
materials, rearrangement of the compositions, changes to
the core structure, variations of the degree of coverage
of the exterior layer and thickness of the layer.
Accordingly, the invention resides in the claims
hereinafter appended.
