Note: Descriptions are shown in the official language in which they were submitted.
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RECYCLABLE PLASTIC STRUCTURAL ARTICLES AND METHOD OF MANUFACTURE
TECHNICAL FIELD
[0001] The disclosed embodiments relate to recyclable plastic structural
articles having a skin
layer and an expanded foam bead core bonded thereto and methods of manufacture
of same.
BACKGROUND
[0002] Substitution of plastic compositions for structural articles formed
from non-plastic
materials may meet objections regarding relatively low physical properties of
the substitute plastic
composition. Manufacturers often blend the plastic composition with other
resins and additives to
improve the physical properties. But, the blends of resins and additives may
decrease the
recyclability of the plastic composition.
[0003] In one example of a structural article suitable for material
substitution, railroad ties support
relatively great weights of railroad locomotives and their attached train cars
with their contents. As
the trains pass over railroad rails supported on railroad ties, the ties
experience substantial vibration,
in addition to the compressive force of the weight. When the ties are not in
use, they are still
subjected to harsh environment extremes of temperature, ultraviolet light, and
moisture. The
degradation of wooden railroad ties through this exposure to the environment
requires that the ties
must be replaced frequently in order to continue to perform their primary
function of supporting the
weight of the train. The wood used to make conventional railroad ties is
increasingly becoming
more expensive. Wooden railroad ties are heavy making the job of replacing
them difficult.
[0004] Articles currently available and not an incorporating in-situ foam core
have various
deficiencies with regard to absorbing water, management of energy, lack of
structure, excessive
weight, or biological degradation
[0005] Manufacturers attempt to insulate an internal cavity of an article from
the external
environment. It is advantageous to have minimal thermal transfer between the
internal cavity in the
external environment. It is also advantageous to have the walls of the energy
management system be
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as structural and as light as possible as well as economical. Adding more
insulation increases the
cost and weight of the energy management system article.
[0006] Certain manufacturers of energy management system articles use
processes such as blow
molding or vacuum forming followed by costly secondary operation of filling
the cavity formed by
the molding process with an injected foam, such as polyurethane foam. Other
manufacturers of
energy management system articles, such as refrigerators, have a large number
of individual
subcomponents, many of which involve bending of sheet metal, followed by
secondary operations of
filling the cavity formed by the subcomponents with injected foam.
SUMMARY
[0007] Disclosed embodiments relate to recyclable plastic structural articles
having a skin layer
and an expanded foam bead core bonded thereto and methods of manufacture of
same. In at least
one embodiment, a plastic structural article includes an elongated tubular
shell having opposed end
sections, a middle section therebetween and an interior cavity. The article
also includes a foam core
comprised of steam expandable polymer beads which when expanded substantially
fill the interior
cavity.
[0008] The article in another embodiment, includes a railroad tie having an
elongated shell
including opposed closed end sections and a middle section therebetween. The
shell defines an
elongate interior cavity. Substantially filling the cavity is a foam core
comprising expanded
polyolefin beads.
[0009] In yet another embodiment, a method of manufacturing a plastic
structural article includes
blow-molding a plastic preform in a mold cavity in the shape of an elongated
member to form an
elongated tubular plastic shell. The shell has opposed end sections, a middle
section therebetween
and a hollow interior cavity. The method also includes forming at least one
fill port and a plurality
of heating ports in the wall of the plastic shell. The shell interior cavity
is filled with expandable
polymer beads. The polymer beads are expanded by injecting a hot, at least
partially vaporized,
heating medium into the heating ports. The polymer beads expand so as to
substantially fill the
interior cavity of the shell. The plastic shell is constrained to limit
expansion of the shell caused by
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the heated expanding polymer beads until the assembly is sufficiently cooled
to limit substantial
further expansion. The mold cavity is opened releasing the plastic structural
article.
[0010] A plastic article is recited having a plastic shell including walls
defining a cavity. Within
the cavity is an in-situ foam core including expanded polymer beads. A layer
of the expanded
polymer beads includes a layer of distorted beads. The in-situ form core has a
thermal bond to the
walls.
[0011] In at least one embodiment, a thermal management system includes a
panel having a
periphery and a skin having a thermal bond to an in-situ foam core. The panel
has a thermal
transmission U-value ranging from 0.1 to 0.17 W/m2 C.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIGURE 1 schematically illustrates a fragmentary isometric view of a
rail pattern according
to at least one embodiment;
[0013] FIGURE 2 schematically illustrates a railroad tie according to at least
one embodiment;
[0014] FIGURE 3 schematically illustrates a cross-sectional view of a railroad
tie along axis 3-3 in
FIGURE 2;
[0015] FIGURE 4 schematically illustrates a cross-sectional view of a railroad
tie along axis 4-4 in
FIGURE 2;
[0016] FIGURE 5 schematically illustrates a cross-sectional view of a second
railroad tie
embodiment;
[0017] FIGURE 6 schematically illustrates a fragmentary cross-sectional view
of a railroad tie
along axis 6-6 in FIGURE 5;
[0018] FIGURE 7 schematically illustrates a fragmentary longitudinal, cross-
sectional view of a
railroad tie and rail system illustrating spike placement; and
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[0019] FIGURE 8 schematically illustrates a cross-sectional view of a third
rail configuration with
a railroad tie;
[0020] FIGURE 9 schematically illustrates a fragmentary cross-sectional view
of a railroad tie with
load sensors;
[0021] FIGURE 10 schematically illustrates a bumper according to at least one
embodiment;
[0022] FIGURE 11 schematically illustrates a cross-sectional view along axis
11-11 of Figure 10;
[0023] FIGURE 12 illustrates a process flow diagram of a method of manufacture
of a railroad tie
according to at least one embodiment; and
[0024] FIGURES 13a -13d schematically illustrate a process of manufacture of a
railroad tie
according to at least one embodiment.
[0025] FIGURE 14 is schematic illustration of an extrusion blow molding
machine equipped with a
foam core system;
[0026] FIGURES 15a-15i schematically illustrate a more detailed process of the
manufacture of a
foam filled blow molded article;
[0027] FIGURES 16a-16d illustrate a bead filled gun in various states of
operation;
[0028] FIGURE 17 is a diagram of mold pressure versus time prior to and during
the bead fill
process;
[0029] FIGURE 18 is a more detailed schematic illustration of the array of
steam pins in the mold
and the associated manifolds and alternative connections to the air steam
vacuum in vent lines;
[0030] FIGURE 19 is a cross-sectional view illustrating a steam pin actuator
and an enlarged steam
pin tip region;
[0031] FIGURE 20 schematically illustrates an isometric view of a water-going
vessel according
to at least one embodiment;
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[0032] FIGURE 21 schematically illustrates an isometric view of a buoy
according to at least one
embodiment;
[0033] FIGURE 22 schematically illustrates an isometric view of a spoiler for
a vehicle according
to at least one embodiment;
[0034] FIGURE 23 schematically illustrates an isometric view of a hot tub
system according to at
least one embodiment;
[0035] FIGURE 24 schematically illustrates an isometric view of an ironing
board according to at
least one embodiment;
[0036] FIGURE 25 schematically illustrates an isometric cross-sectional view
of a precast floor
support according to at least one embodiment;
[0037] FIGURE 26 schematically illustrates an isometric view of a class IX
shipping container
according to at least one embodiment;
[0038] FIGURE 27 schematically illustrates an isometric view of a running the
board for use with a
vehicle according to at least one embodiment;
[0039] FIGURE 28 schematically illustrates an isometric view of a ramp of for
use in loading a
vehicle according to at least one embodiment;
[0040] FIGURE 29 schematically illustrates an isometric view of a surfboard
according to at least
one embodiment;
[0041] FIGURE 30 schematically illustrates an isometric view of a roll-around
cart according to at
least one embodiment;
[0042] FIGURE 31 schematically illustrates an isometric view of a moulding for
use with a
building according to at least one embodiment;
[0043] FIGURE 32-34 schematically illustrates in an isometric view of highway
bumper systems
according to at least one embodiment;
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[0044] FIGURE 35 schematically illustrates an isometric view of a playground
slide according to at
least one embodiment;
[0045] FIGURE 36 schematically illustrates an isometric view of a storage shed
according to at
least one embodiment;
[0046] FIGURE 37A-37E schematically illustrates a method of producing an
article having an in-
situ foam core according to at least one embodiment;
[0047] FIGURE 38A-38E schematically illustrates a method of producing an
article having an in-
situ foam core according to at least one other embodiment;
[0048] FIGURE 39 diagrammatically illustrates a method of producing an article
having an in-situ
foam core according to another embodiment;
[0049] FIGURE 40 diagrammatically illustrates a method of producing an article
having an in-situ
foam core according to another embodiment;
[0050] FIGURE 41 schematically illustrates a method of producing an article
having an in-situ
foam core according to another embodiment;
[0051] FIGURE 42 schematically illustrates a fragmentary isometric view of an
oil containment
system according to at least one embodiment;
[0052] FIGURE 43 schematically illustrates an oil containment system flotation
chamber;
[0053] FIGURE 44 schematically illustrates a cross-sectional view of an oil
containment system
flotation chamber along axis A-A of FIGURE 43.
[0054] FIGURE 45 schematically illustrates panels for a refrigerator system
according to at least
one embodiment;
[0055] FIGURE 46 schematically illustrates panels for a tote according to at
least one embodiment;
[0056] FIGURE 47 schematically illustrates panels for a personal cooler
according to at least one
embodiment;
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[0057] FIGURE 48 schematically illustrates a beer keg according to at least
one embodiment; and
[0058] FIGURE 49 schematically illustrates a refrigerated van for a semi-
trailer according to at
least one embodiment.
DETAILED DESCRIPTION
[0059] As required, detailed embodiments of the present invention are
disclosed herein; however, it
is to be understood that the disclosed embodiments are merely exemplary of the
invention that may
be embodied in various and alternative forms. The figures are not necessarily
to scale; some features
may be exaggerated or minimized to show details of particular components.
Therefore, specific
structural and functional details disclosed herein are not to be interpreted
as limiting, but merely as a
representative basis for teaching one skilled in the art to variously employ
the present invention.
[0060] Except where expressly indicated, all numerical quantities in the
description and claims,
indicated amounts of material or conditions of reaction and/or use are to be
understood as modified
by the word "about" in describing the broadest scope of the present invention.
Practice within the
numerical limits stated should be desired and independently embodied. Ranges
of numerical limits
may be independently selected from data provided in the tables and
description. The description of
the group or class of materials as suitable for the purpose in connection with
the present invention
implies that the mixtures of any two or more of the members of the group or
classes are suitable.
The description of constituents in chemical terms refers to the constituents
at the time of addition to
any combination specified in the description and does not necessarily preclude
chemical interaction
among constituents of the mixture once mixed. The first definition of an
acronym or other
abbreviation applies to all subsequent uses herein of the same abbreviation
and applies mutatis
mutandis to normal grammatical variations of the initially defined
abbreviation. Unless expressly
stated to the contrary, measurement of a property is determined by the same
techniques previously or
later referenced for the same property. Also, unless expressly stated to the
contrary, percentage,
"parts of," and ratio values are by weight, and the term "polymer" includes
"oligomer," "co-
polymer," "terpolymer," "pre-polymer," and the like.
[0061] It is also to be understood that the invention is not limited to
specific embodiments and
methods described below, as specific composite components and/or conditions to
make, of course,
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vary. Furthermore, the terminology used herein is used only for the purpose of
describing particular
embodiments of the present invention and is not intended to be limiting in any
way.
[0062] It must also be noted that, as used in the specification and the
pending claims, the singular
form "a," "an," and "the," comprise plural reference unless the context
clearly indicates otherwise.
For example, the reference to a component in the singular is intended to
comprise a plurality of
components.
[0063] Throughout this application, where publications are referenced, the
disclosure of these
publications in their entirety are hereby incorporated by reference into this
application to more fully
describe the state-of-art to which the invention pertains.
[0064] Regarding Figure 1, a section of railroad track is shown having a rail
pattern 10 comprising
two lengths of a railroad rail 14 that supports a maximum length of a span of
a railroad car or
locomotive from truck to truck. In at least one embodiment, rail pattern 10
comprises 5 to 50
railroad ties 12. In another embodiment, rail pattern 10 comprises 20 to 35
railroad ties 12. In yet
another embodiment, rail pattern 10 comprises 25 to 32 railroad ties 12.
[0065] In at least one embodiment, rail pattern 10 includes railroad ties 12
situated on a rail bed 20.
Ties 12 support at least two rails 14 which are parallel and spaced apart.
Rail 14 is connected to
railroad tie 12 with a plate 16 connected to rail 14. Plate 16 is fastened to
railroad tie 12 by one or
more spikes 18.
[0066] Turning now to Figure 2, an embodiment of railroad tie 12 is
schematically illustrated.
Railroad tie 12 has two end sections 30 and a middle section 32. End section
30 includes a top
surface 34 to which plate 16 is fastened. Opposed and parallel to top surface
34 is bottom surface 36
which is in contact with rail bed 20. Connecting top surface 34 and bottom
surface 36 are two sides
38 and 40. An angle 42 between side 38 and top surface 34 may be perpendicular
or range from 60
to 120 . An angle 44 between side 40 and surface 34 may also be perpendicular
or, in another
embodiment, range from 60 to 120 . Sides 38 and 40 may be linear, or
curvilinear as illustrated in
Figure 3.
[0067] The height of the railroad tie 12 between top and bottom surfaces 34
and 36 may range from
4 inches to 16 inches in various embodiments. The width between sides 38 and
40 may range from 4
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inches to 16 inches in different embodiments. The width between sides 38 and
40 may be effective
to create a short column.
[0068] Middle section 32 includes a top surface 50 and a bottom surface 52
opposed and spaced
apart from top surface 50. Connecting top surface 50 and bottom surface 52 are
sides 54 and 56.
Sides 54 and 56 may be linear, or curvilinear such as convex or concave, as
illustrated in Figure 4.
[0069] A transition 58 between the top surface 34 of end section 30 and top
surface 50 of middle
section 32 may be linear or curvilinear. A transition 60 between either sides
38 and 54 or sides 40
and 56 of the end section 30 and the middle section 50 may be linear or
curvilinear. In at least one
embodiment, the intersection of transitions 58 and 60 forms a Coons corner
geometry 62.
[0070] Turning now to Figure 3, a cross-sectional view of the end section 30
of railroad tie 12
along axis 3-3 of Figure 2 is schematically illustrated. Wall 80, which
includes outer periphery top
and bottom surfaces 34 and 36, as well as sides 38 and 40, defines an interior
cavity 82 into which a
core 84 is formed. Wall 80 may be formed from a polymeric composition. The
polymeric
composition may include thermoplastic and/or thermoset polymers. In at least
one embodiment, the
polymeric composition is recyclable. Non-limiting examples of polymeric
compositions suitable for
wall 80 include polyolefins, such as polypropylene and polyethylene.
[0071] In certain embodiments, especially when the plastic standard articles
are exported to cold
environment, wall 80 includes a blow moldable thermoplastic
polyolefin/polypropylene blend, a
thermoplastic elastomer/polypropylene blend interpenetrating polyolefin blend,
a thermoplastic
having a glass transition temperature less than -80 C/polyolefin blend, a
hetergeneous polymer
blend, and a thermoplastic having a glass transition temperature less than -20
C/polyolefin blend, a
thermoplastic vulcanizate/polyolefin blend. In certain embodiments,
hetergeneous polymer blends
having a crystalline thermoplastic phase and a high molecular weight or
crosslinked elastomeric
phase may be supplied by Exxon Mobile or Advanced Elastomer Systems.
[0072] In at least one embodiment, the ratio of thermoplastic polymer to
polyolefin ranges from 5
wt.% to 70 wt.% of the blend. In another embodiment, the ratio of
thermoplastic polymer to
polyolefin ranges from 10 wt.% to 40 wt.%.
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[0073] The thickness of wall 80 may range from 0.03 inches to 0.5 inches in at
least one
embodiment. In another embodiment, the thickness of wall 80 may range from
0.125 inches to 0.25
inches. In the illustrated embodiment, the wall is made of an elongated tube
of polypropylene
material having a wall thickness ranging from 0.14 inches to 0.17 inches
before shrinkage which is
blow-molded into the shape of the tie 12 having a finished wall thickness
ranging from 0.13 to 0.16
inches.
[0074] Core 84 may include steam-expandable polymer particles 86, such as
expanded polyolefin
polymer beads. In at least one embodiment, the expanded polyolefin polymer
beads includes
expanded polypropylene polymer beads (EPP). In yet another embodiment, core 84
includes
expanded high molecular weight polypropylene polymer beads. In yet another
embodiment,
homopolymer beads are included in the expanded polyolefin beads in order to
increase the stiffness
of core 84. As a non-limiting example, when the homopolymer polyolefin is a
homopolymer
polypropylene, the stiffness increases such that a 100,000 lb load yields a
5.8% strain and a
compression of only 0.007 inches. In another example, the strain ranges from
2% strain to 10%
strain. In at least one embodiment, EPP may be formed in situ by injection of
steam into
polypropylene beads to form steam-injected expanded polypropylene. It is
understood that a portion
of core 84 may comprise polyolefin beads in an unexpanded configuration or a
partially expanded
configuration.
[0075] Steam-injected expanded polypropylene may have a density ranging from 1
lb/ft3 to 20
lbs/ft3. In yet another embodiment, steam-injected EPP may have a density
ranging from 1.5 lbs/ft3
to 10 lbs/ft3. In yet another embodiment, steam-injected EPP may have a
density ranging from 2
lbs/ft3 to 6 lbs/ft3. In yet another embodiment, steam-injected EPP may have a
density ranging from
3 lbs/ft3 to 5 lbs/ft3.
[0076] A load applied by a train may be more broadly distributed throughout
core 84 by wrapping
plate 16 around the sides 38 and 40 as shown in Figure 3. Plate 16 forms an
inverted "U" shape in
order to support sides 38 and 40 and limits outward defection under load.
[0077] In Figure 4, middle section 34 of railroad tie 12, in certain
embodiments, includes a cavity
84 which is filled with expanded polyolefin. The expanded polyolefin particles
86 filling cavity may
have a density that is less than, equal to, or greater than the density of
expanded polyolefin in cavity
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84 of end section 30. In another embodiment, end section 30 has a density of
EPP that is at least 1
lb/ft3 less than the density of EPP in middle section 34. While Figures 3 and
4 describe having 3
density zones, it is understood that railroad tie 12 may have one or more
density zones without
exceeding the scope or spirit of the embodiment. Further, it is understood
that, in certain
embodiments, the density zones may comprise a relatively uniform gradient of
density throughout
portions of the railroad tie 12 without relatively clear demarcation of one or
more density zones. In
the illustrated embodiment, the density of the EPP beads in the end section is
5 lbs/ft3 while the
density of the EPP beads in the middle section is 3 lbs/ft3.
[0078] Turning now to Figure 5, in at least one embodiment an angled railroad
tie 112 suitable for
use in a curved railroad pattern is schematically illustrated in cross-
sectional view. Angled railroad
tie 112 is formed from an angular wall section 110 which defines three sub-
cavities 114, 116 and
118. Into cavity 114, a first expanded polyolefin 120 is formed. Into sub-
cavity 116, a second
expanded polyolefin 122 having a density less than expanded polyolefin 120 is
formed. Into cavity
118, a third expanded polyolefin 124 having a third density is formed. In
other embodiments, the
densities of expanded polyolefins 120, 122 and 124 may be equal or different.
[0079] The angle of angled railroad tie 112 is given by angle a Angle e is
determined by a camber
needed for safe passage of a train in a curve in the rail track pattern 10. It
is desirable to have angled
railroad tie 112 because rail bed 20 may be uniformly prepared as a flat and
level bed surface. In at
least one embodiment, the angle e may range from 0.1 to 30 . In another
embodiment, the angle e
may range from 0.5 to 100. In yet another embodiment, the angled railroad tie
comprises a wedge
shape.
[0080] Turning now to Figure 6, a transverse, cross-sectional view along axis
6-6 of Figure 5 is
illustrated. Bottom surface 36, in at least one embodiment, includes a
retention structure 126 which
interacts with rail bed 20 to form an interference that reduces the tendency
of the railroad tie 112 to
move when a directional force is applied to railroad tie 112 by the passage of
a train.
[0081] Figure 7 illustrates a ringed shank fastener 140, such as a spike for
use with railroad tie 12.
The expanded polyolefin 142 moves aside as the ringed shank spike 140 is
driven into railroad tie 12
in at least one embodiment. The expanded polyolefin 142 then rebounds to wrap
around the ring
shanks 144 of the spike 140 to secure the rail 14 and plate 16 to railroad tie
12.
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[0082] In at least one embodiment ring shank 144 extends 0.100 inches to 0.300
inches from the
root of spike 140. Ring shank 144 is configured as an inverted frustro conical
section. Spike 140
may include a plurality of such frustro conical sections sequentially
configured along the
longitudinal axis of spike 140. It is understood that other shapes providing
an undercut may be
suitable for use with spike 140.
[0083] Figure 8 illustrates a third rail configuration for use with a railroad
tie 150 according to at
least one embodiment. Railroad tie 150 includes an expandable polyolefin 152
in a cavity defined
by wall 154. A third rail device 156 is mounted on railroad tie 150. Third
rail device 156 is
electrified to supply power to an electrical train. Electrical power is then
transferred to rails 158
back to the power station.
[0084] In addition, Figure 8 illustrates having plate 16 inset into a plate
retention structure 172
embossed into tie 150. It is understood that retention structure 126 and plate
retention structure 172
may be present in the same railroad tie.
[0085] Figure 9 illustrates a fragmentary cross-section of a railroad tie 160
in which sensors are
embedded according to at least one embodiment. One or more sensors, such as a
RFID chip 162
with a piezoelectric strain gauge 164, may be embedded in an expanded
polyolefin 168 in a cavity
defined by wall 170. An optional conduit 166 may permit electrical connection
of sensor 164 to an
external signaling device. Sensors 162 and/or 164 may be introduced into the
expanded polyolefin
168 prior to injection of the steam to expand the polyolefin beads. In another
embodiment, the
sensors may be place in the railroad tie 160 after demolding of the railroad
tie by mechanical
insertion means known in the art.
[0086] A typical railroad tie 12, in at least one embodiment, has a weight
ranging from 10 lbs. to
200 lbs. for a 9 inch by 7 inch by 102 inch railroad tie. In another
embodiment, railroad tie 12 has a
weight ranging from 20 lbs. to 100 lbs. In yet another embodiment, railroad
tie 12 has a weight
ranging from 30 lbs. to 75 lbs so that the tie can be carried by a single
worker.
[0087] When railroad pattern 10 uses railroad tie 12, the expanded polyolefin
core functions as an
energy absorber. In at least one embodiment, railroad tie 12, when using
expanded polypropylene as
the core, experiences a deflection before permanent set in excess of 25%.
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[0088] The force needed to deflect the railroad tie may be characterized by a
spring rate which is a
function of a cross-sectional area bending moment of the railroad tie 12, a
length of the railroad tie
12 and an elastic modulus of the expanded polyolefin. Having a higher spring
rate than wood, the
expanded polyolefin in the railroad tie 12 may have a greater yield stress
than wood. Having greater
yield stress may result in the expanded polyolefin railroad tie having greater
energy absorption than
the wood railroad ties. Increased energy absorption by the expanded polyolefin-
based railroad ties
may result in a relatively quiet railroad system when the train passes over
the expanded polyolefin-
based railroad ties.
[0089] The spring rate of the railroad tie may be increased or decreased by
increasing or decreasing
the density of the expanded polyolefin in the railroad tie core by use of
methods disclosed in certain
embodiments herein.
[0090] Polyolefin beads and methods of manufacture of unexpanded polyolefin
beads suitable for
making the illustrated embodiment are described in Japanese patents
JP60090744, JP59210954,
JP59155443, JP58213028, and U.S. Patent No. 4,840,973, all of which are
incorporated herein by
reference. Non-limiting examples of expanded polyolefins are ARPLANK and
ARPRO available
from JSP, Inc. (Madison Heights, MI). Alternatively expanded polystyrene of
polyethylene bead
can be used but polypropylene is preferred for the railroad tie application.
[0091] The expanded polypropylene, such as the JSP ARPROTs EPP, which has no
external shell,
exhibits physical properties such as in Table 1.
Table 1
Property Test Units Value
Method
Density AS TM lb s/ft3 1.0 2.8 3.7 4.2 4.6
5.0
D-3575
Compressive ASTM lbf/in2
Strength D-3575
@ 10% deflection 8.4 32 44 53 61 68
@ 25% deflection 11 42 57 65 76 84
@ 50% deflection 19 54 73 84 97 112
@ 75% deflection 41 111 155 183 220 251
Compressive Set ASTM %
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Property Test Units Value
Method
D-3575
@ 25% deflection 8 7 7 7 7 7
@ 50% deflection 16 12 12 12 12 12
Compressive Creep ASTM % <0.5 1 1.5 2.5 3.0 3.5
D-3575
@ 1000 hr
Service Temperature ASTM C 100 100 100 100 100 100
D-3575
[0092] Turning now to Figures 10 and 11, an embodiment of a bumper 180,
such as the
bumper suitable for a large truck chock block, a parking lot bumper, a dock
bumper, a golf cart
bumper, a roof for a low-speed vehicle, or ship fenders is schematically
illustrated in isometric view
in Figure 10. Bumper 180 has an elongated tubular shape with one or more
facets 182. The roof for
the low-speed vehicle may range in thickness from 0.25 inches to 2 inches,
preferable 0.75 inches to
1.25 inches.
[0093] In Figure 11, a longitudinal cross-sectional view along axis 11-11 of
Figure 10 is
schematically illustrated. The core 184 has a substantially uniform density of
steam-expanded
polypropylene beads throughout the entire profile of the elongated bumper 180.
A pair of through
holes 181 extend through the bumper to enable the bumper to be attached to the
parking lot surface.
Holes 181 can be formed by a large steam pins, while smaller blind holes 183
are formed on the part
underside by steam pins spaced as needed across the part.
[0094] The shell 190, in at least one embodiment, is comprised of two layers:
an inner layer 186
and an outer layer 188. The two layers 186 and 188, are formed concurrently
when a blow mold
parison is formed with two layers by coextrusions or methods known in the art.
Inner layer 186 may
have a first set of properties, such as recycled plastic composition, and
outer layer 188 may have a
second set of properties, such as including an ultraviolet light resistance
package or a pigment. It is
understood that outer layer 188 may have a different composition from inner
layer 186. As a non-
limiting example, outer layer 188 may include a co-polymer or 0-5 wt% of
linear low density
polyethylene (LLDPE) in order to increase flexibility of outer layer 188
resulting in reduced stress
cracking. It is further understood that while two layers are illustrated here,
a plurality of layers is
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contemplated. In another embodiment, the number of layers may range from one
to 11. It is
preferred that inner layer 186, outer layer 188, and core 184, have similar,
if not identical
compositions, to improve the recyclability of bumper 180.
[0095] Figure 12 diagrammatically illustrates a method for manufacturing
the recyclable
plastic structural article having multiple core density zones, in at least one
embodiment, which
includes blow-molding a hollow elongated shell in step 200. Feed apertures,
such as an inlet, and
heating ports are cut or pierced during step 202 into the blow-molded
elongated shell of step 200.
Polyolefin pellets are fed into the cavity of the elongated shell of step 200
during step 204. The
density of polyolefin pellets in the lower first end of the elongated shell,
are feed in first followed by
the middle section, and/or the second end is controlled in step 204 during
filling of the shell in one or
more density zones. Steam injection needles can be inserted during step 206
into each density zone
through heating ports or alternately the needles can be inserted at sit 204
before filming. In step 208
steam is injected at sufficient pressure effective to cause the polypropylene
pellets to expand in step
210. Excess pressure is vented to the atmosphere in step 212. The molded
railroad tie is allowed to
cool in step 214. The mold is opened in step 216 to release the blow-molded
recyclable plastic
structural article.
[0096] Blow-molding step 200 preferably includes extruding a tubular
parison. The mold is
closed on the parison and about 90 to 100 lbf/in2 pressure gas is applied to
the parison interior
cavity. The gas injected into the parison causes the plastic to conform to the
shape of the walls of
the mold. One or more gas injection needles are introduced to the parison
prior to the cooling the
plastic on the mold walls. Spacing between steam injection needles may vary
with the density of
unexpanded beads because the steam migration is limited. In at least one
embodiment, the spacing
between adjacent steam injection needles ranges from 2 inches to 6 inches.
[0097] In at least one embodiment, at approximately one half of the
length of the cooling
period, typically referred to as a blow cycle, feed apertures, such as fill
ports, are cut. The cutting
tools are withdrawn from the mold and a staged fill sequence for polyolefin
pellets begins in step
204. The filling is preferably conducted from the bottom up. Upon completion
of the staged fill
sequence, the feed apertures are optionally closed with spin-welded plugs. The
steam injection
needles are injected to introduce steam for an injection time period ranging
from 0.5 to 3 seconds, an
injection time period sufficient to expand the bead. In at least one
embodiment, steam is introduced
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as super heated steam. In another embodiment, steam is introduced at a
pressure less than the clamp
pressure on the mold sections. In yet another embodiment, steam is introduced
in a range of 15
lbf/in2 to 120 lbf/in2. In at least one embodiment, the steam is introduced at
280 Fahrenheit and 60
lbf/in2 pressure. After a cooling time period, when post-mold expansion
effectively ceases, the mold
is opened to release the blow-molded railroad tie. In at least one embodiment,
the time to cool the
railroad tie so that post mold expansion does not substantially occur ranges
from about 1 minute to 8
minutes. Optionally, the mold may be vented to the atmosphere to release
excess gas pressure or the
mold may be burped, i.e., opened briefly and then re-closed.
[0098] Embodiments of steps 200, 202, 204, 206, and 208 are illustrated
in Figures 13a -
13d.
[0099] In Figure 13a, blow mold sections 240 and 242 define a blow mold
cavity 244 into
which a molten polyolefin parison 246 is extruded from an extruder 248.
Parison 246 defines an
internal parison cavity 250.
[0100] In Figure 13b, blow mold sections 240 and 242 close upon parison
246. Gas 260 is
injected into parison cavity 250 inflating the hot parison 246 while still
soft and deformable to
conform to the walls of the blow mold cavity 244 defining a shell 262 having a
cavity 264 which
may be larger than the original parison cavity 250.
[0101] In Figure 13c, steps 202 and 204 of Figure 10 are illustrated as
feed apertures 270,
272, and 274 are cut through shell 262. Staged filling begins as unexpanded
EPP beads 268 are
introduced to cavity 264 through an EPP introduction device fitted to blow
mold section 242. At a
first stage, EPP beads 268 are introduced through feed aperture 270. When the
cavity 264 is
substantially filled to the height of feed aperture 270, a second stage
introduces unexpanded EPP
beads 268 through aperture 272 until that portion of cavity 264 is
substantially filled. A third stage
introduces unexpanded EPP beads 268 through aperture 274 until the cavity 264
is filled.
[0102] EPP introduction device (not shown) is withdrawn from apertures
270, 272, and 274.
The apertures 270, 272, and 274 are plugged. Steam injection needles 276, 278,
280, 282 are
inserted through blow mold section 242 and shell 262 into the filled cavity
264.
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[0103] In Figure 13d, steam is injected through steam injection needles
276, 278, 280, 282
into unexpanded beads 268 causing the beads to expand forming a core 290 in
the area that was
previously cavity 264, and bonded to the shell 262.
[0104] Figure 14 illustrates an extrusion blow molding machine 300 having
a vertical
extruder 302 for forming an elongate hollow plastic parison 304 out of plastic
skin material supplied
by hopper 306. A bold molding machine controller 308 controls the operation of
extruder 302 and a
mold actuator 310 capable of moving two mold halves 312 and 314 positioned on
opposing lateral
sides of the extruded parison 304 and between an open position illustrated and
a closed position to
entrap the parison within an internal cavity formed by internal mold cavity
halves 316 and 318.
Mold halves 312 and 314 are specifically adapted for forming a foam core
article using the described
methods. The mold halves are provided with a series of steam injector pins 320-
328. Although only
five steam pins are illustrated for simplicity purposes, the steam pins will
be provided in an array
having a sufficient number to thoroughly steam the product to be formed.
[0105] At least one of the mold halves will be provided with a bead fill
gun 330 having a
bead fill port which communicates with mold interior cavity portion 316. For
simplicity purposes a
single fill gun is illustrated, however, multiple filled guns at various
locations can be provided as
illustrated previously with respect to Figures 13a-13d. Preferably, at least
one fill gun is located
generally proximate the upper region of the mold cavity as illustrated in
Figure 14. Fill gun
operation is controlled by a foam core system controller 332. Preferably, foam
core system
controller 332 is a separate controller which communicates with the blow
molding machine
controller 308. In that way, the foam core system can be added to existing
blow molding extruding
systems. Alternatively, the foam core system controller can be incorporated
into the blow molding
machine controller for new machines or in reconstructed blow molding extrusion
machines.
[0106] The bead fill gun 330 is supplied with expanded bead under
pressure from taffl( 334
which is coupled to the fill gun 330 by an interconnecting supply line
containing and valve 336
controlled by foam core controller 332. The expanded bead is supplied to
pressurized taffl( 334 from
an expanded bead hopper 338 by a supply line containing a valve 340, again
regulated by the foam
core system controller 332. The pressure of the expanded bead in taffl( 334 is
maintained by a three-
way pressure regulator valve 342 coupling the pressurized taffl( 334 to a
source of pressurized air
344. The operation of the three way pressure regulator valve 342 is controlled
by the foam core
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controller enabling the controller to pressurize the tank to the desired
pressure, preferably, 80 to 120
pounds per square inch gauge pressure (PSIG) and to alternatively vent the
tank 334 to atmosphere
to facilitate the introduction of more bead into the tank.
[0107] The steam pins 320-328 can be alternatively connected to
pressurized air source 344,
steam source 346, a vacuum source 348 and a vent 350. To facilitate these
alternative connections
and to enable a number of steam pins to be associated together in zones, a
steam pin manifolds 352
and 354 are provided. In the illustrate schematic, only two manifolds are
shown for simplicity,
however, preferably, up to ten and more preferably about 6 manifolds can be
operated by the foam
core system controller. Each of the manifolds are connected to a series of
steam pins and each
manifold has an input/output connection to each of the air source, steam
source, vacuum and vent
344, 346 and 348 and 350. Each of the input/output connections is controlled
by a flow valve
operated by the foam core system controller.
[0108] In operation, with the mold shown in the open position, as
illustrated in Figure 14, the
extruder forms a tubular hollow plastic parison 304 of the thermoplastic skin
material. Once the
parison has reached the desired length relative to the cavity, the blow
molding machine controller
issues a closed mold signal causing the mold drive 310 to close the mold
halves together. Upon
issuance of the closed mold signal, the foam core system controller begins
operation and temporarily
takes over control of the blow molding machine. Immediately prior to or
contemporaneously with
the closing of the mold, the extruder will provide pressurized air into the
internal cavity defined by
the parison in what is known as a puffing operation so that when the mold is
closed as illustrated in
Figure 15a, a portion of the partially inflated parison wall will contact a
region of the mold cavity as
illustrated. One or more steam pins in this first contacted region of the mold
will be actuated driving
a steam pin needle 356 into the hollow interior cavity of the blow molded
parison 304. Once the
first actuated needle or needles 356 extend into the parison, the foam core
controller, opens the air
valve supplying air to manifold 354 which in turn supplies air to needle 356
to blow the plastic
parison 304 into a shell fully conforming it to the interior surfaces of the
cavity halves 316 and 318
of mold halves 312 and 314. Once fully inflated, as shown in Figure 15b, the
controller will open air
valves to the other manifolds 354 so that all the needles from all of the
steam pins projecting provide
preesurized gas such as air into the interior cavity of the parison 304 to
fully conform to the interior
shape of the mold cavity. As will be described further in detail,
subsequently, foam core system
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controller will cause all of the steam pins to be vented initially allowing
the internal pressure within
the shell to drop from the blow molding pressure of 80 to 120 PSIG, preferably
90 PSIG. Once the
pressure drops down to about 40 PSIG the fill gun cutter punches or cuts a
hole into the hollow shell.
The cutter then retracts as illustrated in Figure 15 D, and the filling
process begins. When the
pressure nears the taffl( pressure, all of the steam pins will be closed
accept the most remote steam
pins from the fill gun which were main vented whereupon the control valve 336
will open and the
fill gun mandrel will open along via flow from the pressurized taffl( 334 into
the shell cavity in a
controlled manner. The venting of the manifold associated with the remote
steam pins will be
controlled to maintain a desired part cavity pressure. When the pressure drops
below that of the
pressurized bead tanks 334, which is about 30 PSIG + or ¨ 2PSIG bead flows
into the shell cavity.
The pressure of the vented manifold is maintained approximately 5PSIG below
the fill tank pressure
providing adequate pressure differential for the quick and orderly filling of
the cavity with bead
without forming voids.
[0109] Once the distal region of the cavity is initially filled with
beads, then the next set of
steam pins is vented as is illustrated in Figure 15e and the filling operation
continues zone by zone
until the final collection of steam pins proximate the fill gun is vented.
Upon the achieving a
substantially completely filled with beads, the fill gun closes as will be
described in more detail.
Subsequently, once closed, all of the steam vents are vented to atmosphere.
Once vented to
atmosphere, the beads further expand in size from their fill state and grow
approximately 3% in
volume as the pressure within the cavity cell drops from 25 PSIG to
atmospheric preassure. This
causes the beads to completely fill the cavity and to be slightly deformed as
they contact one
another.
[0110] Once the cavity is vented, the bead steaming process will begin
one-half of the steam
pins will be connected to a steam source while the other half of the steam
pins will be connected to
the vacuum source or alternatively, connected to atmosphere and the system
operated without a
vacuum source. After a relatively short time period, the initial steam pins
provided with steam will
be connected to the vacuum source and the remaining pins will be connected to
the steam vent and
the steam process will continue until the expanded beads are heated
sufficiently to expand and melt
together and to bond to the wall of the skin. Following the steam process as
illustrated in Figure
15g, the condensate, removal and cooling step begins. One half of the steam
pins will be connected
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to a source of pressurized air while the other half of the steam pins will be
vented to atmosphere.
Then, the pins originally connected to pressurized air will be vented to
atmosphere and the vented
pins will be connected to a source of pressurized air. This step removes
condensate from the bead
steaming from the expanded bead and causes the bead to be cooled. This process
continues until the
bead has reached the desired temperature, whereupon the steam pin needles are
refracted and the
mold halves opened so the part can be de-molded as shown in 15i. At this
point, the foam core
controller passes control of the operation back to the blow molding machine
controller so that the
next part can be formed.
[0111] An enlarged schematic illustration of blow gun 330 is shown in
Figures 16a-16d,
illustrating various states of operation. In Figure 16a, the fill gun is shown
in the closed orientation.
Blow gun 330 is installed in mold cavity half 312. The fill gun has three main
components; a fill
tube 358 having a distal end flush with the mold cavity interior wall forming
a fill aperture
surrounded by frusto conical valve seat 360. An elongate mandrel 362 has a
distal end forming a
face 364 conforming to the cavity wall when the mold halves are in the closed
position and a frusto
conical surface 366 which cooperates with frusto conical seat 360 of the fill
tube 358 to form a tight
seal when the mandrel is moved to the closed position as shown in Figure 16a.
When closed,
mandrel 362 prevents beads from entering the cavity and the base of the
mandrel 364 and the
associated face of the distal end of the fill tube 358 conformed to the
interior cavity wall of mold
half 312 as the plastic parison 304 is blown into a shell conforming to the
cavity interior as
illustrated in Figure 16a. Preferably, after the plastic shell wall is cooled
sufficiently and is
maintained in conformity to the mold cavity by the interior gas pressure, a
tubular hole saw 368 is
operated. The tubular hole saw 368 surrounds fill tube 358 and rotatably fits
within a
correspondingly sized cylindrical cavity in mold half 312. Tubular hole saw
368 is provided with an
external drive gear or sprocket operatively driven by a belt chain or
mechanical gear to rotate the
saw relative to the mold. A conventional drive 370 can be utilized provided as
relatively compact
and meets the minimal speed and load requirements of a hole saw. The hole saw
is also provided
with an actuator mechanism such as a fork operated by a hydraulic or pneumatic
cylinder to advance
the linear rotating hole saw into the cavity interior as shown in Figure 16D,
cutting a round plug out
of the shell wall whereupon the actuator 372 will retract the hole saw and the
operation of the drive
mechanism can be terminated.
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[0112] With the hole in the shell formed, the fill process can begin. As
shown in Figure 16c,
the mandrel 362 is retracted by a linear actuator 374 such as pneumatic or
hydraulic cylinder or an
electric linear actuator such as ball screw to cause the frusto conical face
366 to lift off of conical
seat 360 allowing bead to flow into the interior of the plastic shell. The
fill process continues until
the plastic shell is completely filled as previously described.
[0113] In order to close the fill gun, it is necessary to remove the bead
from the region of the
conical seat 360 and the corresponding frusto conical face 366. To do so, a
tubular passage 376
allows air to be provided to a series of outlet ports in frusto conical face
366, the high pressure blast
of air exiting these outlet ports, clears the bead allowing the mandrel to be
closed. In order to enable
the bead to be blow back out of the fill tube, optionally, the fill valve 336
can be maintained in the
open position and the pressure in the tank 334 can be reduced enabling the
bead to be pushed back
through the fill gun and fill line into the pressure tank 334.
[0114] In the embodiment illustrated in Figure 14, a single pressure tank
is provided coupled
to a source of bead. If multiple density bead is to be used, it is possible to
have multiple pressure
tanks, each with its own supply of different density bead coupled to a single
fill gun. After a desired
amount of the first bead is introduced, the pressure tank can be vented and
pressurized air supplied to
the mandrel to blow the bead in the fill tube back into the pressure tank,
whereupon the pressure tank
valve can be closed and the pressure tank valve for a second source of bead of
a different density can
be connected to the fill gun to continue the filling process. Accordingly, it
is possible to build a
railroad tie as described previously, having high density beads in the
railroad tie ends and a low
density bead in the center utilizing a single fill gun and the upper end of
the railroad tie as molded,
the fill gun alternatively being connected to the two different pressure tanks
containing different
density bead.
[0115] Figure 17 is a pressure diagram illustrating the pressure in the
mold cavity interior as
the part is initially blown, vented and filled with bead. The pressure
represented by the dotted line is
proportional to the pressure within the mold and pressure will be measured at
the steam pin manifold
or closer to the mold at the steam pin. During the blowing process, the cavity
pressure is at a blow
pressure 380 which is about 80-120 PSIG, preferably about 90 PSIG. When the
blow cycle is
complete, the steam pin vents open causing a rapid pressure drop as
illustrated in region 381 of
pressure curve. At a selected pressure, in this instance approximately 40 PSIG
illustrated at point
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383, all the steam pins are closed except for the most distal steam pins
allowing the pressure to
continue to drop at a reduced rate. At the next selected pressure point 385,
which is approximately
30 PSIG, the hole saw cuts the fill hole and refracts. When the pressure drops
further and reaches a
fill pressure, which in this embodiment, illustrated at approximately 25 PSIG.
at point 388 in Fig. 17,
the fill gun mandrel opens allowing the bead to introduced into the shell
cavity, causing a
momentary spike in pressure. After the first most distal zone is filled, the
second set of vents open,
at point in time 389, allowing filling to continue. The third set of vents at
point in time 391. When
the cavity is full of bead, the fill gun goes through a clear and close step
causing a momentary spike
in pressure as illustrated at time 393. During the filling process, the
pressure is maintained at the
desired fill pressure by regulating the outlet of the manifold using a vent
valve controlled by the
system controller 332. Once the fill gun is closed, the manifold is fully
vented allowing all of the
pins to vent.
[0116] For the purpose of illustration, Figure 14 only illustrated two
manifolds and a limited
number of steam pins. A typical part will require more than two manifolds with
a series of steam
pins associated with each manifold. Each of these manifold are independently
connectable to air,
steam, vacuum and vent. Figure 18 illustrates a mold for an elongate part
having a substantial width
such as a structural panel. The mold 380 is provided with 12 steam pins 382
oriented in four rows of
three with each row representing a zone connected to one of four manifolds
384, 384', 384¨ and
384". Each of the manifolds has an outlet which is preferably located at its
lower most point
connected to a controllable valve 336 which is regulated by the foam core
system controller 332.
Each manifold has four inlets in the embodiment illustrated, connected to air
source 334, steam
source 346, vacuum source 348 and vent 350. As previously noted, it is
possible to operate this
system without a vacuum source utilizing the vent during the condensate
removal process. The
inlets in the manifolds are controlled independently by air valve 388, steam
valve 390, vacuum valve
392 and vent 394, each operated by the foam core system controller. The
corresponding valves for
each of the manifolds are also independently controlled by the system
controller in the preferred
embodiment. Accordingly, a great deal of flexibility in the control of the
foam core process is
achievable.
[0117] One example of the process flexibility obtainable by the
previously described
structure is illustrated by the preferred steaming process. In order to
minimize the amount of
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condensate introduced into the bead, prior to opening steam valve 346 to
introduce steam into the
manifold, the outlet valve 386 is opened allowing all of the condensate to
drain from the manifold.
When steam valve 390 is open, due to the relatively large size of the outlet
opening in valve 386,
steam will flow rapidly through the manifold and exit, removing any wet steam
from the manifold
and heating the manifold. Once hot the outlet valve 386 is rapidly closed
causing steam to be
injected into the bead through the associated steam pin needles. Each manifold
is purged and
preheated prior to each steaming operation, thereby maximizing the temperature
and dryness of the
steam introduced in order to heat the bead with the minimum amount of water,
which in turn
minimizes the amount of drying time necessary to remove the condensate.
[0118] Preferably, each of the steam pins is provided with a linear
actuator to drive the steam
pins in and out of the mold cavity. A representative steam pin actuator is
illustrated in Figure 19.
Steam pin assembly 390 includes a needle 392 having a distal end which
projects into the mold
when extended and a proximate end connected to a steam line 394 which is
coupled to the manifold.
The steam needle 392 is affixed to a support plate 396 which can be shifted
between a needle
extended position as shown and a needle retracted position illustrated in
dotted outline. The support
plate 396 is linearly moved by a pneumatic double ended cylinder 398 between
two adjustable stop
positions. Cylinder 398 is mounted to the mold half 312 by support bracket as
illustrated. The tip of
the needle as illustrated in the exploded view, has a sharp point and a series
of steam ports extending
over the portion of the needle that extends through the wall of the plastic
shell wall 304, preferably
the steam ports in the needle wall end short of the shell 304 wall.
Preferably, the steam needle 392 is
made of relatively thin wall stainless steel in order to have good corrosion
resistance and low
thermal mass.
[0119] Figure 20 schematically illustrates a water-going vessel 410, such as a
sit-in kayak having a
deck and a hull, a sit-on-top kayak or a one-or two-person watercraft. Water-
going vessel 410
includes a wall 412 having a thermal bond to an in-situ foam core 414. In-situ
foam core 414 is
formed by fully expanding pre-expanded beads. The thermal bond includes a
cooled joint formed
from a molten and/or softened layer from wall 12 adjacent to a molten and/or
softened layer of foam
core 414, with an optional layer of intermingled portions of wall 412 layer
and foam core 414 layer.
It is understood that the optional layer may include a layer of distorted
shape beads adjacent to the
walls. It is understood that portions of other intermediate layers may be
present in the thermal bond,
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such as a tie layer or a metal insert embedded in the article. A sit-in kayak
will have a hull section
and a deck which are molded separately bonded together. A sit-on-top kayak can
be made as one
piece.
[0120] In at least one embodiment, wall 412 thickness may range from 0.02
inches to 0.5 inches. In
another embodiment, wall 412 thickness may range from 0.125 inches to 0.25
inches.
[0121] In at least one embodiment, in-situ foam core 414 thickness may range
from 0.15 inches to 6
inches. In another embodiment, in-situ foam core 414 thickness may range from
0.2 inches to 4
inches. In another embodiment, in-situ foam core 414 thickness may range from
0.5 inches to 1 inch.
[0122] Wall 412, in at least one embodiment, is formed of a composition of any
moldable
composition. Non-limiting examples of the composition include, but are not
limited to, a liquid
silicone rubber, a synthetic rubber, a natural rubber, a liquid crystal
polymer, a synthetic polymer
resin, and a natural polymer resin. In another embodiment, wall 412 is a
formed of a composition of
a thermoplastic polymer, a thermoset polymer, or blends thereof having a
viscosity ranging from 0.1
grams/10 min to 40 grams/10 min. The viscosity is measured according to ASTM D-
1238 at 190 C
with a 2.16 kg weight. In yet another embodiment, wall 412 is formed of a
composition of a
polyolefin, including polypropylene and polyethylene, having a viscosity
ranging from 1 grams/10
min to 30 grams/10 min.
[0123] In-situ foam core 414 in at least one embodiment, is formed of a
composition of any fluid-
expandable material. Examples of fluid-expandable material include, but are
not limited to, a
polyolefin polymer composition, a biopolymer expandable bead, an alkenyl
aromatic polymer or
copolymer, a vinyl aromatic polymer resin composition, and a polystyrene
polymer composition. In
at least one embodiment, the polyolefin polymer composition includes
polyolefin homopolymers,
such as low-density, medium-density, and high-density polyethylenes, isotactic
polypropylene, and
polybutylene-1, and copolymers of ethylene or polypropylene with other
polymerizable monomers,
such as ethylene-propylene copolymer, ethylene-vinyl acetate copolymer,
ethylene-acrylic acid
copolymer, ethylene-ethyl acrylate copolymer, and ethylene-vinyl chloride
copolymer. These
polyolefin resins may be used alone or in combination. Preferably, expanded
polyethylene (EPE)
particles, cross-linked expanded polyethylene (xEPE) particles,
polyphenyloxide (PPO) particles,
biomaterial particles, such as polylactic acid (PLA), and polystyrene
particles are used. In at least
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one embodiment, the polyolefin polymer is a homopolymer providing increased
strength relative to a
copolymer. It is also understood that some of the particles may be unexpanded,
also known as pre-
puff, partially and/or wholly pre-expanded without exceeding the scope or
spirit of the contemplated
embodiments.
[0124] Pre-expanded beads, in at least one embodiment, are the resultant bead
after raw bead has
undergone a first expansion step of a two-step expansion process for beads.
During the first
expansion step, raw bead is expanded to 2% to 95% of the fully expanded bead
size. The fully
expanded bead is the bead that forms in-situ foam core. In another embodiment,
pre-expanded bead
is result of the first expansion step where raw bead is expanded from 25% to
90% of the fully-
expanded bead size.
[0125] A fluid for the second expansion step of the two-step expansion process
for beads causes the
pre-expanded beads to expand completely to form the fully expanded beads.
Examples of the fluid
include, but are not limited to, steam and superheated steam.
[0126] Polyolefin beads and methods of manufacture of pre-expanded polyolefin
beads suitable for
making the illustrated embodiments are described in Japanese patents
JP60090744, JP59210954,
JP59155443, JP58213028, and US patent number 4,840,973 all of which are
incorporated herein by
reference. Non-limiting examples of expanded polyolefins are ARPLANKO and
ARPROO
available from JSP, Inc. (Madison Heights, MI). The expanded polypropylene,
such as the JSP
ARPROO EPP, has no external wall.
[0127] In at least one embodiment, in-situ foam core 414 density, after
expansion by steam, ranges
from 1 lb/ft3 to 25 lbs/ft3. In at least one embodiment, in-situ foam core 414
density ranges from
1.5 lbs/ft3 to 15 lbs/ft3. In at least one embodiment, in-situ foam core 414
density ranges from 2
lbs/ft3 to 9 lbs/ft3. In at least one embodiment, in-situ foam core 414
density ranges from 3 lbs/ft3 to
6 lbs/ft3.
[0128] In at least one embodiment, wall 412 with a range of 0.025 inch
thickness to 0.1 inch
thickness is comprised of a metallocene polypropylene. Such a combination is
found to improve
adhesion between wall 412 and in-situ core from 414 formed of EPP.
[0129] It is understood that each article disclosed herein may be recyclable.
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[0130] Turning now to Figure 21, a buoy 420 is schematically illustrated
according to at least one
embodiment. Buoy 420 includes a wall 422 and an in-situ foam core 424 having a
thermal bond to
wall 422 as schematically illustrated in a cut-away view. Buoy 420 optionally
includes a light 426,
an anchoring station 428, a molded-in-tube 418, and a ballast 416. If this
buoy 420 should be struck
by a vessel or debris puncturing wall 422, the lack of water uptake by in-situ
foam core 424 means
that the buoy 420 remains afloat. In-situ foam core 414 absorbs less than 1
weight percent water, in
certain embodiments, correcting buoy deficiencies in previously made buoys. It
is understood that
each wall in each of the figures has the same range of embodiments as wall
412. It is further
understood that each in-situ foam care in each of the figures has the same
range of embodiments as
in-situ foam core 414.
[0131] Turning now to Figure 22, a spoiler 430 includes a wall 432 having a
thermal bond to an in-
situ foam core 434 according to at least one embodiment. Encapsulated by and
helping to form in-
situ foam core 434 is a tube 436 having a composition with sufficiently high
melting temperature so
as to resist melting in the steam and/or superheated steam. A non-limiting
example of the
composition is a polyamide composition.
[0132] Steam and superheated steam, in certain embodiments, especially those
with show surfaces
on all exterior surfaces, such as the spoiler, is injected into the spoiler
430 through an inlet of tube
436, which functions as a manifold and has a plurality of apertures 458
allowing steam or
superheated steam into in-situ foam core 434 to cause the pre-expanded beads
to fully expand
forming foam core 434. Inlet 438, in certain embodiments, is suitable as a
retention device for a
fastener.
[0133] Turning now to Figure 23, a hot tub system 440 is schematically
illustrated according to at
least one embodiment. Hot tub system 440 includes a top 442 including a wall
444 having a thermal
bond to an in-situ foam core 446. Top 442 further includes a living hinge 448.
Panel 450 supporting
top 442 includes wall 452 having a thermal bond to an in-situ foam core 454.
Top 442 is particularly
desirable because of its initially lower weight relative to current systems,
and its lack of absorption
of water, which is limited to less than one weight percent of water in certain
embodiments. In
another embodiment, in-situ foam cores 446 and/or 454 absorb less than 0.5 wt.
% water. It is
understood that while a hot tub system 440 is illustrated, other water
containing articles, such as but
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not limited to, a spa, shower, a bathtub and an interior insert 456 to the hot
tub system 440 are
contemplated.
[0134] Turning now to Figure 424, an ironing board 460 is schematically
illustrated according to at
least one embodiment. Ironing board 460 includes wall 462 having a thermal
bond to an in-situ foam
core 464.
[0135] Turning now to Figure 25, a precast floor support 470 includes a wall
472 and an in-situ
foam core 474 having a thermal bond to wall 472. During construction of many
buildings, recently,
precast floor support 470 would receive a layer of light weight concrete 476
to form a floor, such as
a mezzanine floor. Precast floor support 470, in at least one embodiment,
exhibits creep of 0.5% to
3.5% when measured at 1000 hr according to ASTM D-3575 when in-situ foam core
474 density
ranges from 1.0 to 5.0 lbs/ft3.
[0136] In at least one embodiment, preexpanded comprise homopolymer
composition pre expanded
beads, in order to increase the stiffness of in-situ foam core 474. As a non-
limiting example, when
the homopolymer beads are a homopolymer polypropylene, the stiffness increases
such that a
100,000 lb load yields a 5.8% strain and a compression of only 0.007 inches.
In another example,
the strain ranges from 2% strain to 10% strain.
[0137] In at least one embodiment, precast floor support 470 yields surprising
savings because it is
such a good thermal insulator that the users no longer need to add additional
layers of insulation for
energy usage reduction. In at least one embodiment, precast floor support 470
has a u-value of less
than 0.17. In another embodiment, precast floor support 470 has a u-value of
less than 0.145.
[0138] Turning now to Figure 26, an International Air Transport Association
(IATA) class IX
shipping container 500 is schematically illustrated according to at least one
embodiment. Class IX
shipping container 500 includes a top 502 and a bottom 504. Bottom 504 has a
plurality of
embossments 506 formed with a wall 508 having a thermal bond to an in-situ
foam core 510 to wall
508 as illustrated in the cut-away section. At least one of top 502 and bottom
504 includes a sealing
gasket 512. Optionally, one or more securing bands 514 may be applied to
further secure top 502 to
bottom 504..
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[0139] In at least one embodiment, in-situ foam core 510 and/or wall 508
comprises a non-
conductive divider. In at least one embodiment, the non-conductive divider
surface resistance
maximum is greater than 1012 ohm per square; where surface resistance is the
inverse measure of
conductivity when measured to standard ANSI/ESD-S 20.20-1999. In another
embodiment, in-situ
foam core 510 and/or wall 508 prevent electrostatic discharge. In at least one
embodiment class IX
shipping container 500 is suitable for airborne cartage of primary non-
rechargeable batteries, such as
lithium metal batteries, and/or rechargeable batteries, such as lithium ion
batteries. It should be
understood that in at least one embodiment, in-situ foam core 510 and wall 508
comprise an IATA
Class VIII shipping container suitable for corrosive materials.
[0140] Turning now to Figure 27, a running board 522 is schematically
illustrated according to at
least one embodiment as attached to a vehicle 520. Running board 522 includes
wall 524 having a
thermal bond to an in-situ foam core 526. Running board 522 reduces the weight
of a vehicle
running board by at least 30% relative to current running boards, while
retaining structural strength.
It is understood that while a van vehicle is illustrated, running board 522
may be used for a
passenger truck, a class 6-8 tractor cab, a mower, a mining vehicle, and other
suitable vehicles where
the first step is at least 6" or more above the ground. It is also understood
that while running board
522 is illustrated as fixed, a retractable and/or deployable running board or
vehicle step is
contemplated. Further, it should be understood that running board 522 may
comprise a ramp system
for a van accessible vehicle for use by handicapped people.
[0141] Turning now to Figure 28, a ramp 530 is schematically illustrated
according to at least one
embodiment. Ramp 530 permits wheeled carts to traverse a gap between a loading
dock 532 and a
vehicle 534. Ramp 530 includes a wall 536 having a thermal bond to an in-situ
foam core 538.
Ramp 530 reduces the weight by at least 25 pounds relative to current metal
and/or wood ramps,
which makes it more ergonomically desirable for vehicle drivers who must
position the ramp at each
stop.
[0142] Turning now to Figure 29, a surfboard 540 is schematically illustrated
according to at least
one embodiment. Surfboard 510 includes wall 542 having a thermal bond to in-
situ foam core 544.
It should be understood that while surfboard 540 is illustrated, is exemplary
of other similar boards,
such as a sail board, a small sailboat, and a skateboard deck.
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[0143] Turning now to Figure 30, a roll-around cart 550 is illustrated
according to at least one
embodiment. Roll around cart 550 includes a panel 552, an optional embossment
558, and an
optional lockable door 554. Lockable door 554 includes a living hinge 556.
Panel 552 includes wall
560 having a thermal bond to an in-situ foam core 562.
[0144] Turning now to Figure 31, a molding 570, such as a doorjamb or a window
frame is
schematically illustrated according to at least one embodiment. Molding 570
includes a wall 572
having a thermal bond to an in-situ foam core 574. Molding 570 is
significantly more stable in
terms of thermal expansion and construction than current PVC frames. Molding
570 has a thermal
expansion coefficient less than 5 x 10-6 in/in/ F.
[0145] Turning now to Figures 32, 33 and 34 a highway bumper system, such as,
but not limited to,
plastic structural articles including a highway guard rail end terminal 580, a
jersey wall 586, and a
V-shaped barrier 592, are schematically illustrated in an isometric view
according to at least one
embodiment. In Figure 32, highway guard rail end terminal 580 is an impact
attenuator and includes
a wall 582 having a thermal bond to an in-situ foam core 584. In at least one
embodiment, the end
terminal 580 may have a plurality of slots arranged in a staggered or an
offset pattern of slots 598
with bolts 608 mounted to a guard rail 612 having a support 614 to ground
providing a sliding
resistive force sufficient to stop a 70 mph vehicle in less than 10 seconds.
The foam core energy
absorption capacity and foam core damping response surprisingly, in at least
embodiment, with slots
598 creates an essentially square wave of energy absorption. In at least one
embodiment, the
highway bumper system ultimately compresses less than 25% when struck at 70
mph by a 3000 lb.
vehicle.
[0146] In at least one embodiment, highway bumper system includes a energy
absorbing bumper
616 disposed between guard rail 612 and support 614. Bumper 616 includes a
wall 618 having a
thermal bond 642 to an in-situ foam core 644
[0147] In Figure 33, V-shaped barrier 592, in at least one embodiment, is
disposed on ground, and
includes a wall 594 having a thermal bond to an in-situ foam core 594. The V-
shaped barrier 592 is a
device for absorbing the energy of a vehicle and protecting the same in the
event of a collision with a
relatively immovable hazard along a highway such as a bridge abutment. It is
understood that while
the V-shaped barrier 592 is illustrated, other shapes such as a torroid, may
be used in other
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embodiments without exceeding the scope or spirit of the embodiments. In
addition, it is also
understood that the V-shaped barrier 592 may be combined with other energy
absorbing components
such as flexible annular rings, for a non-limiting example, a plurality of
tires, without exceeding the
scope and spirit of the embodiments.
[0148] In Figure 34 jersey wall 586, in at least one embodiment, includes a
wall 588 having a
thermal bond to an in-situ foam core 588. In another embodiment, jersey wall
586 may include a
connector 606, such as J-J hook or U-channel embedded in at least one end in
order to facilitate
joining multiple jersey walls together to form a barrier wall. In at least
embodiment, the foam core
588 provides jersey wall 586 with sufficient structural mechanical strength
and energy damping to
pass NCHRP-350 Level TL-2 and TL-3, as well as European Containment Level Test
with a test
rating of H2, and a European Containment rating at levels T 1 , T2, and T3. It
is understood that
while a jersey barrier-type shape is illustrated, other shapes, such as an F-
shape and a Constant Slope
shape, are contemplated within the scope and spirit of the invention. Jersey
wall 586 is significantly
lighter than conventional precast concrete barriers reducing the amount of
labor and capital
equipment necessary to install the barrier. In at least one embodiment, jersey
wall 586 is sufficiently
portable that it can be used to protect workers on the roadway and provide a
warning function, such
during nighttime closures, and then be economically removed by a 2x4 wheel
drive pickup truck on
a daily basis, such as at the end of the work shift, effectively replacing the
highway orange barrels
currently used. The highway orange barrels provide the warning function to
drivers, but do not
significantly inhibit drivers from entering the work zone, thereby possibly
endangering workers on
the roadway.
[0149] Turning now to Figure 14, a playground equipment component, such as a
playground slide
200 is schematically illustrated in an isometric perspective view according to
at least one
embodiment. Playground slide 600 includes a wall 602 having a thermal bond to
an in-situ foam
core 604. Playground slide 600 is another embodiment of a plastic structural
article. It is
understood that while a playground slide 600 is illustrated, other typical
structural playground
articles, such as, but not limited to, a teeter-totter and components of
playground equipment,
especially tubular, rectangular, or square cross-sectional components having
spans in excess of 2
meters with cross-section maximum dimensions of 10 mm or suitable sizes for
young children's
hands are contemplated with the scope and spirit of the embodiments of the
invention.
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[0150] Turning now to Figure 36, a storage shed 620 is schematically
illustrated in an isometric
view according to at least one embodiment. Storage shed 620 includes
components such as a roof
panel 622 having a wall 624 having a thermal bond to an in-situ foam core 626.
Storage shed 620, in
certain embodiments, has roof panel 622 with a minimum flat dimension
exceeding 3 feet, where 3-
foot span is the standard maximum for conventionally constructed shed roof
panels. In another
embodiment, storage shed 620 roof panel 622 has a minimum flat dimension equal
to or exceeding 4
feet. In another embodiment, the storage shed 620 roof panel 622 has a minimum
area of 4 foot by 8
foot, that when in clear span width, has a maximum sag of 0.75" relative to
the horizontal plane of
the panel. In yet another embodiment, the storage shed 620 roof panel 622 has
a minimum area of 4
foot by 8 foot, that when in clear span width, has a maximum sag of 0.25"
relative to the horizontal
plane of the panel. In yet another embodiment, the storage shed 620 roof panel
622 has a minimum
area of 4 foot by 8 foot, that when in clear span width, has a maximum sag of
0.35" relative to the
horizontal plane of the panel when tested at 90 C.
[0151] In at least one embodiment, storage shed 620 has a segmented door 628
and roof panel 622
and is certified to resist hurricane force winds in excess of a design
pressure rating exceeding DP30.
In another embodiment, storage shed 620 has a double door 628 and roof panel
622 and is certified
to resist hurricane force winds in excess of a design pressure rating
exceeding DP40. In yet another
embodiment, storage shed 620 has a door 628 and roof panel 622 and is
certified to resist hurricane
force winds in excess of a design pressure rating of DP50. In at least one
embodiment, segmented
door 628 includes a plurality of profiles 630 having a wall 632 and an in-situ
foam core 634 having a
thermal bond 636 bonding wall 632 and in-situ foam core 634.
[0152] In at least one embodiment, storage shed 620 in anchored by a footer
650 of a cementious
composition which encapsulates a base 654 which interlocks with a wall panel
652 of storage shed
620. Wall panel 652 includes a hook attachment 656 rolls into lock with a
retention member 658 of
base 654.
[0153] Figures 37A -37E schematically illustrate a method of producing a
plastic structural article
having an in-situ foam core according to at least one embodiment. Regarding
Figure 37A, has a
nozzle 712 containing a molten polymer composition 714. Molten polymer
composition 714 is
injection molded into a mold 716 having a first mold portion 718 and a second
mold portion 720.
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The first and second mold portions 718 and 720, respectively, define a cavity
722 within the mold
716 into which molten polymer composition 714 is being injected through at
least one sprue 724.
[0154] Figure 37B includes having a fluid 730 from a fluid source 732 enter
mold cavity 710 which
is now, at least, partially filled with molten polymer 714 by pushing molten
polymer 714 towards the
walls of mold 716. When molten polymer 714 is pushed completely to the wall of
mold 716 by the
fluid 730 in Figure 37C, a cavity 736 is formed inside the injection molding
shot of molten polymer
714 and excess molten polymer 714 is displaced into a spillover trap 728
through valves 26 (Figure
37A). Fluid 730 cools molten polymers 714 sufficiently such that a hollow
article 746 is self-
supporting. Fluid 730 is removed from cavity 736 through a vent 734. Vent 734
is subsequently
closed.
[0155] The steps of Figures 37A-C are illustrated by US Patent No. 6,375,892
which is
incorporated herein by reference.
[0156] Figure 37D has a port cap 738 (Figure 37C) removed and includes a
rotary cutter 740 that
passes through a mold port 742 cutting an aperture 744 in a wall 754 of the
hollow article 746.
Rotary cutter 740 withdraws from aperture 744 and a bead dispenser 748 enters
aperture 744. Valve
726 is closed.
[0157] In Figure 37D, pre-expanded beads 750 are dispensed from a bead source
752 to bead
dispenser 748 and from bead dispenser 748 into cavity 736 of hollow article
746. Bead dispenser
748 withdraws from aperture 744. It is understood that pre-expanded beads 750
may be compressed
during dispensing.
[0158] In Figure 37E, a steam pin 760 and a steam vent 762 are inserted into
aperture 744. Steam
764 from steam source 766 is injected into cavity 736 causing rapid expansion
of pre-expanded
beads 750 which tightly pack cavity 736 forming an in-situ foam core 768
having a thermal bond to
wall 754. A plastic structural article 770 having a skin 772 formed of a
cooled polymer and in-situ
foam core 768 is released from mold 716 by separating the first mold portion
718 from the second
mold portion 720.
[0159] The steps of Figures 37D-E are illustrated by US patent application
numbers 13/358181,
13/005190, and 12/913132 all of which are incorporated herein by reference.
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[0160] Turning now to Figure 38A, an injection-molded part 824 is formed
between a first mold
portion 820 and a second mold portion 822 by any injection-molding method
known in the art.
[0161] In Figure 38B, first mold portion 820 is raised to allow insertion of
pre-expanded beads 826
and a tube 828, as shown in Figure 38C. Tube 828 is comprised of a material
having a sufficiently
high melting point that tube 828 will not melt when exposed to steam or
superheated steam. Tube
828 has small apertures capable of permitting steam or superheated steam to
infiltrate pre-expanded
beads 826.
[0162] In Figure 38D, first mold portion 820 is closed, thereby compressing
pre-expanded beads
826 and tube 828. In figure 38E, steam or superheated steam from steam source
830 passes through
valve 832 which is connected to tube 828. Steam interacts with the pre-
expanded beads 826, thereby
expanding pre-expanded beads 826 to fully expanded beads forming in-situ foam
core 834. In-in
situ foam core 834 is thermally bonded to injection-molded part 824. Injection-
molded part 824 and
in-situ foam core 834 comprise a structural plastic article, which can be
removed from between first
mold portion 820 and second mold portion 822 when at least one of the mold
portions separates
from the other.
[0163] At least one embodiment illustrated in Figure 39, in step 900 a method
for manufacture of
an article having one plastic layer includes providing a mold portion having a
mold surface and
flanges adjacent to the mold surface. A plastic sheet having a thermoplastic
composition is secured
to the flanges in step 902. In step 904 the thermoplastic sheet is
thermoformed to be adjacent to the
mold surface to form a thermoformed thermoplastic skin. A plate is situated
adjacent to the flanges
forming a cavity with the thermoformed thermoplastic skin in step 906. In step
908, unexpanded
and/or pre-expanded polymer particles are introduced into the cavity when the
pressure in the cavity
is at least 30 pounds per square inch less than the pressure exerted on the
unexpanded and/or pre-
expanded polymer particles. During introduction, the unexpanded and/or pre-
expanded particles are
compressed by more than 10 vol%. The unexpanded and/or pre-expanded particles,
in certain
embodiments, rebound in size by at least 5 vol. % to approximately their
original volume before
introduction. In certain embodiments the particles may rebound to exceed their
original volume. In
step 910, steam is introduced into the cavity causing the unexpanded polymer
particles to expand to
form expanded polymer particles in step 912. Once the particles have
substantially stopped
expanding, the plate is removed in step 914. In step 916, the thermoformed
structural plastic article
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is removed from the mold portion. The structural plastic article includes a
plastic layer bonded to
expanded polymer particles. The bonding occurs during the steps 910 through
912 when the
polymer particles are expanding using steam to form an in-situ core with the
plastic layer.
[0164] Referring now to Figure 40, a method is recited for forming an article
using twin sheet
thermoforming skins with the expanding foam core. In step 1030 a first mold
portion having a first
mold surface and first flanges adjacent to first mold surface is provided. In
step 1032, a first
thermoplastic sheet is secured to the first flange. In step 1034, the first
thermoplastic sheet is
thermoformed adjacent to the mold to form the first thermoformed thermoplastic
skin.
[0165] In step 1036, a second mold portion having a second mold surface and
second flange
adjacent to the second mold surface is provided. In step 1038, a second
thermoplastic sheet is
secured on to the second flange. In step 1040, the second thermoplastic sheet
is thermoformed to be
adjacent to the second mold surface to form a second thermoformed
thermoplastic skin.
[0166] The first and second thermoformed thermoplastic skins are connected
along the first and
second flange in step 1042, closing the mold. Portions of the first and second
skins are spaced apart
defining a cavity. In step 1044, unexpanded polymer particles are introduced
into the cavity. In step
1046, steam is introduced into the cavity. The unexpanded polymer particles
expand to form
expanded polymer particles in step 1048. After the polymer particles cease
substantially to expand,
the first and second mold portions are opened. In step 1052, the thermoformed
structural plastic
article is removed from the mold portions.
[0167] It is understood that unexpanded polymer particles may include
partially expanded polymer
particles. It is also understood that the polymer particles may cease
substantially to expand when the
pressure in the mold in certain embodiments is 0.5 lbf/in2 or less. In other
embodiments, the
pressure in the mold when the polymer particles may cease to expand
substantially may range from
0.1 lbf/in2 to 1 lbf/in2.
[0168] In Figure 41, another embodiment of a method of manufacture of the
structural plastic
articles is disclosed. In step 1060, a first mold portion and a second mold
portion each having a
mold surface are provided. The two mold surfaces define a first cavity. In
step 1062, a plastic solid
material is introduced into the first cavity. In step 1064, the plastic solid
material is molded
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rotationally under heat to melt the plastic solid to form plastic liquid
materials. In step 1066, the
liquid plastic materials coat the first and second mold surfaces. In step
1068, the first and second
mold surfaces are cooled to crystallize the plastic liquid materials to
plastic solid skin which defines
a second cavity. In step 1070, unexpanded or partially expanded polymer
particles are introduced
into the second cavity. In step 1072, steam is introduced into the second
cavity. In step 1074, the
unexpanded polymer particles are expanded by the steam to form expanded
polymer particles.
When the expansion of the polymer particles has substantially ceased, the
first and second mold
portions are opened in step 1076. In step 1078, the rotationally molded
structural plastic article is
removed from the mold portion. It should be understood, that curable plastic
materials may be
introduced in step 1062 as a substitute for the plastic solid materials
without exceeding the scope or
spirit of the embodiment. It is also understood, that some liquid materials in
certain embodiments,
will require little or no heat beyond the ambient room temperature to begin
curing the plastic liquid
materials to crystallize or otherwise solidify the plastic liquid material in
step 1068. It is also
understood that rotationally molding the structural plastic article may use
processes such as
rotational molding or rotocasting.
[0169] Figure 42 schematically illustrates an oil containment boom 1100
according to at least one
embodiment. Boom 1100 includes a flotation chamber 1102 connected to a
freeboard 1104.
Freeboard 1104 is also connected to a skirt 1106 that is draped into the water
6-10 feet. Skirt 1106 is
connected at the end opposite the freeboard 1104 to a tension member 1108.
Tension member 1108
supports a ballast member 1110 which aids in keeping skirt 1106 positioned
upright in the water.
Chambers 1102 can be located on one side or both sides of freeboard 1104.
[0170] Figure 43 schematically illustrates flotation chamber 1102. A plurality
of flotation
chambers 1102 are connected by fasteners through a plurality of apertures 1112
in an alternating
configuration to opposite sides of freeboard 1104 in at least one embodiment.
In another
embodiment, the plurality of flotation chambers 1102 are connected to one or
more sides of the
freeboard in order to provide sufficient buoyancy to keep freeboard 1104
approximately upright in
heavy swells at sea.
[0171] Figure 44 schematically illustrates a cross-sectional view along axis A-
A of Figure 42.
Flotation chamber 1102 includes a wall 1114 having a thermal bond 1124 to an
in-situ foam core
1126. Thermal bond 1124 includes a cooled connection having a molten or
softened portion of wall
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1114, a molten or softened portion of in-situ foam core 1126, and a co-mingled
layer including wall
1114 and in-situ foam core 1126. In-situ foam core 1126 includes a first
density zone 1116 having a
greater density than a second density zone 1118. Second density zone provides
greater buoyancy is
especially advantageous in seas with high waves or when an oil containment
boom 1100 is above
average booms in weight. Apertures 1112 can also experience extra stresses. In
at least one
embodiment, the blowmolding parison is fed more slowly or with more material
into areas so as to
increase the wall thickness in higher stress areas, such as area 1120.
[0172] It should be understood that other embodiments may use a heating medium
other than steam
without exceeding the scope of contemplated embodiments. It is further
understood that the
expanded polyolefin may be formed using a heating medium in cooperation with a
blowing agent,
such as pentane.
[0173] Figure 45 schematically illustrates a refrigerator 1210 having a panel
1212. Panel 1212 has
a wall 1214 with a thermal bond (not shown) to an in-situ foam core 1216,
according to at least one
embodiment. In another embodiment, a door panel 1218 includes an inner surface
having an
embossment 1220 and a protrusion 1222 molded into at least one surface of door
panel 1218.
Attached to door panel 1218 is a refrigerator handle 1224 having a skin (not
shown) and an in-situ
foam core (not shown).
[0174] Figure 46 schematically illustrates a tote 1240 suitable for holding
relatively high-
temperature liquids, such as liquid asphalt, liquid malic acid, and molten
sulfur, in at least one
embodiment. Tote 1240, in another embodiment, is suitable for holding sub-
ambient temperature
liquids, such as liquid nitrogen, as well as refrigerated produce requiring
temperature in the range
from 0 C to 4 C.
[0175] Figure 47 schematically illustrates a personal cooler 1260 having a
skin 1262 and an in-situ
foam core 1264.
[0176] In-situ foam core 1232 is prepared by injecting steam into pre-expanded
beads dispensed
into cavity (not shown) defined by walls 1214 (Figure 45), 1244 (Figure 46),
and/or 1262 (Figure
47). It should be understood that the pre-expanded beads may have different
original diameters and
form, when fully expanded, in-situ foam cores 1216, 1246, and/or 1264,
respectively.
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[0177] Figure 48 schematically illustrates a beer keg 1280 according to at
least one embodiment.
Beer keg 1280 has a wall 1282 having a thermal bond to an in-situ foam core
1284. The light weight
and durability of beer keg 1280 relative to a conventional aluminum beer keg
are appreciated by
customers. In addition, beer distributors appreciate that the expensive
aluminum kegs that some
users recycle for cash are replaced by beer keg 1280, for which recyclers pay
relatively less cash.
[0178] Figure 49 schematically illustrates a semi- truck with a trailer 1300.
Trailer 1300 is
comprised of a plurality of panels 1312, according to at least one embodiment.
Panels 1312, in at
least one embodiment, are interlocked into a van floor 1302 and/or a van roof
1304. Panels 1312
have the wall 1314 with a thermal bond 1306 to the in-situ foam core 1316.
Thermal bond 1306
includes a cooled member of a molten or softened portion of skin 1314, a
molten or softened portion
of in-situ foam core 1316, and a co-mingled layer of skin 1314 and in-situ
foam core 1316.
[0179] In at least one embodiment, the wall 1314 thickness may range from 0.02
inches to 0.5
inches. In another embodiment, wall 1314 thickness may range from 0.125 inches
to 0.25 inches.
[0180] In at least one embodiment, in-situ core 1316 thickness may range from
0.15 inches to 6
inches. In another embodiment, in-situ foam core 1316, thickness may range
from 0.2 inches to 4
inches. In another embodiment, in-situ foam core 1316 thickness may range from
0.5 inches to 1
inch.
[0181] Walls 1314 in at least one embodiment, are formed of a composition of
any moldable
composition. Non-limiting examples of the composition include, but are not
limited to, a liquid
silicone rubber, a synthetic rubber, a natural rubber, a liquid crystal
polymer, a synthetic polymer
resin, and a natural polymer resin. In another embodiment, walls 1314 are
formed of a composition
of a thermoplastic polymer, a thermoset polymer, or blends thereof having a
viscosity ranging from
0.1 grams/10 min. to 40 grams/10 min. The viscosity is measured according to
ASTM D-1238 at
190 C with a 2.16 kg weight. In yet another embodiment, walls 1314 are formed
of a composition
of a polyolefin including a polypropylene and polyethylene having a viscosity
ranging from 1
grams/10 min. to 30 grams/10 min.
[0182] In-situ foam core 1316 in at least one embodiment, is formed of a
composition of any fluid-
expandable material. Examples of fluid-expandable material include, but are
not limited to, a
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polyolefin polymer composition, a biopolymer expandable bead, an alkenyl
aromatic polymer or
copolymer, a vinyl aromatic polymer resin composition, and a polystyrene
polymer composition. In
at least one embodiment, the polyolefin polymer composition includes
polyolefin homopolymers,
such as low-density, medium-density, and high-density polyethylenes, isotactic
polypropylene, and
polybutylene 1, and copolymers of ethylene or polypropylene with other
polymerized bull
monomers such as ethylene-propylene copolymer, and ethylene-vinyl acetate
copolymer, and
ethylene-acrylic acid copolymer, and ethylene-ethyl acrylate copolymer, and
ethylene-vinyl chloride
copolymer. These polyolefin resins may be used alone or in combination.
Preferably, expanded
polyethylene (EPE) particles, cross-linked expanded polyethylene (xEPE)
particles, polyphenyloxide
(PPO) particles, biomaterial particles, such as polyactic acid (PLA), and
polystyrene particles are
used. In at least one embodiment, the polyolefin polymer is a homopolymer
providing increased
strength relative to a copolymer. It is also understood that some of the
particles may be unexpanded,
also known as pre-puff, partially and/or wholly pre-expanded without exceeding
the scope or spirit
of the contemplated embodiments.
[0183] Pre-expanded beads, in at least one embodiment, are the resultant bead
after raw bead has
undergone a first expansion step of a two-step expansion process for beads.
During the first
expansion step, raw bead is expanded to 2% to 95% of the fully expanded bead
size. The fully
expanded bead is the bead that forms in-situ foam core. In another embodiment,
pre-expanded bead
is the result of the first expansion step where raw bead is expanded from 25%
to 90% of the fully-
expanded bead size.
[0184] A fluid for the second expansion step of the two-step expansion process
for beads causes the
pre-expanded beads to expand completely to form the fully expanded beads.
Examples of the fluid
include, but are not limited to, steam and superheated steam.
[0185] In at least one embodiment, in-situ foam core 1316 density, after
expansion by steam,
ranges from 1 lb/ft3 to 25 lbs/ft3. In at least one embodiment, in-situ foam
core 1316 density ranges
from 1.5 lbs/ft3 to 15 lbs/ft3. In at least one embodiment, in-situ foam core
1316 density ranges from
2 lbs/ft3 to 9 lbs/ft3. In at least one embodiment, in-situ foam core 1316
density ranges from 3 lbs/ft3
to 6 lbs/ft3.
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[0186] In at least one embodiment, walls 1314, with a range of 0.025 inch
thickness to 0.1 inch
thickness, are comprised of metallocene polypropylene. Such a combination is
found to improve
adhesion between walls 1314 and in-situ foam core from 1316 formed of EPP.
[0187] Refrigerator 1210, tote 1240, beer keg 1280, personal cooler 1260, and
trailer 1300, in at
least one embodiment, have thermal transmittance u-values ranging from 0.1 to
0.17 W/m2 C. In
another embodiment, refrigerator 10, tote 1240, personal cooler 60, beer keg
80, and van 100 have
thermal transmission u-values ranging from 0.12 to 0.16 W/m2 C.
[0188] Panel 1218 of refrigerator 1210 consolidates a number of individual
components into one
moldable unit providing a substantial cost improvement relative to current
refrigerator construction
methods.
[0189] Personal cooler 1260 consolidates two parts into one relative to
current personal cooler
construction methods, but also avoids the extra labor costs of the secondary
operation for injecting
polyurethane foam that is in use with current cooler construction methods.
Further, personal cooler
1260 also avoids use of potentially destructive blowing agents relative to the
environment.
[0190] It is understood that while refrigerator 1210, tote 1240, personal
cooler 1260, beer keg 1280,
and trailer 1300 are illustrated in embodiments, other similar structures,
such as commercial ice
making machine systems; chemical tank covers; hot tub covers, walls, and
bases; liquid storage
facilities for use at ports, including those with food-grade composition
walls; and in-flight beverage
carts are some non-limiting articles amenable to manufacture by this method.
[0191] While exemplary embodiments are described above, it is not
intended that these
embodiments describe all possible forms of the invention. Rather, the words
used in the
specification are words of description rather than limitation, and it is
understood that various
changes may be made without departing from the spirit and scope of the
invention. Additionally, the
features of various implementing embodiments may be combined to form further
embodiments of
the invention.
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