Note: Descriptions are shown in the official language in which they were submitted.
RIBBED FILM STRUCTURES WITH VOIDING AGENT
CREATED VISUAL CHARACTERISTICS
[0001] BACKGROUND
[0002] As the costs of resin materials increase along with desires to
minimize the impact
of resin material waste, manufacturers are moving toward use of thinner and
thinner gauges of
resin films in their products. This is particularly true of manufacturers that
implement high
volumes of resin films in various forms, such as resin films for use in
storage and waste
products. While thinner gauge materials can represent obvious cost savings to
the manufacturer,
conventional production mechanisms can mean that use of thinner gauge film
precursors results
in lower durability of the end product. Although some recent technology may
result, in some
cases at least, in relatively thinner gauge products that may be as strong as
their thicker
counterparts, customers naturally sense from prior experience that thinner
gauge materials are
lower in quality and durability.
[0003] One instant cue to a customer of lower quality and durability of a
bag is not only
how thick or thin the bag feels, but also how thin or weak the bag "looks."
Generally speaking,
customers tend to view translucence as an indication of relatively low
strength. Thus, despite the
fact that some conventional mechanisms can improve some aspects of film
strength while
nevertheless using thinner gauge film materials, the translucence of such bags
tends to cause
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< ,
customers to believe the bag is nevertheless low quality. Manufacturers may
try to overcome
these sorts of difficulties by adding colorants or voiding agents to minimize
this issue.
[0004] Depending on how they are used, however, colorants and
voiding agents can
sometimes weaken the chemical bonds in the film, and create a still weaker
film, Moreover, the
use of certain colors in a film or film structure may present unique
challenges. For example,
films with a white color may employ a pigment such as titanium dioxide (TiO2).
However,
titanium dioxide is quite expensive and may significantly increase the cost of
a film that employs
such a pigment. Other conventional mechanisms involve using multiple, very low
gauge films in
a laminate structure, where at least one of the films is colored. However, the
aforementioned
types of color additions to film, and the types of film structures are not
typically well-suited for
some applications and/or have proven to be problematic for various reasons in
addition to those
noted above.
[0005] For example, one color changeable laminate structure (or
"laminate") includes a
pair of films in intimate contact with each other, and further includes a
color generating film
positioned adjacent one of the films. So long as the films are in intimate
contact with each other,
the laminate generates an interference color. However, absent intimate contact
between the
films, no color is generated. Thus, the color changeable laminate may not be
well-suited for use
in environments where, for example, delamination of the films is possible. As
well, production
processes for this structure can be difficult, and in some cases must be
strictly controlled to
ensure intimate contact throughout the entirety of the laminated films.
[0006] Another laminate displays a color change when the laminate
is bent. This is
achieved with a color generating metal disposed on a film of the laminate. The
metal is in
intimate contact with an anodic film, and creates color by light interference
absorption effects.
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Absent intimate contact between the metal and the anodic film however, the
color generation
effects are not achieved. Moreover, production processes can be difficult, and
in some cases
must be strictly controlled to ensure intimate contact between all portions of
the metal and the
anodic film. As well, this laminate may not be well-suited for environments
where: the use of
metal is undesirable or impractical; delamination of the metal and anodic film
is possible; and/or,
it is desired to maintain the color of the laminate notwithstanding temporary
or permanent
changes to the geometry of the laminate.
[0007] As a final example, a further laminate structure can be constructed
to display an
irreversible color change upon delamination of two films in intimate contact
with each other.
Absent intimate initial contact between the films however, the color
generation effects are not
achieved. Thus, production processes must be strictly controlled to ensure
intimate contact
between the films so that when the films are delaminated, the desired effect
is achieved. As well,
this laminate may not be well-suited for environments where it is desired to
maintain the color of
the laminate notwithstanding temporary or permanent changes to the geometry of
the laminate.
Finally, this laminate structure may necessitate user intervention to effect
the delamination
necessary for achievement of the irreversible color change.
[0008] As the foregoing discussion suggests, there is a need for quality
end products that,
notwithstanding other aspects of their appearance and/or tactile impression,
are configured to
provide a positive indication to the consumer as to the quality of those
products.
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BRIEF SUMMARY OF AN EXAMPLE EMBODIMENT
100091 One or more embodiments within the scope of the invention may be
effective in
overcoming one or more disadvantages in the art. In one example embodiment, a
film includes
a coextruded structure having both an extruded ribbed skin layer that includes
a plurality of ribs,
and a core layer. The ribs are spaced apart by a web that is integral with the
ribs. The film also
includes a voiding agent that is substantially more apparent in the ribs than
in the web, such that
a contrast in color and/or color intensity between the ribs and the web is
visible.
[0010] The foregoing embodiment is provided solely by way of example and is
not
intended to limit the scope of the invention in any way. Consistently, various
other embodiments
of an extruded, multi-layer film having a ribbed outer layer, discontinuously
laminated film
structures, and associated production processes, within the scope of the
invention are disclosed
herein.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The appended drawings contain figures of example embodiments to
further
illustrate and clarify various aspects of the present invention. It will be
appreciated that these
drawings depict only example embodiments of the invention and are not intended
to limit its
scope in any way. Aspects of the invention will be described and explained
with additional
specificity and detail through the use of the accompanying drawings in which:
[0012] Figure 1 discloses aspects of an extrusion die such as may be
employed to form
an extruded, ribbed film layer;
[0013] Figure 2a discloses aspects of an MD machine and associated MD
rolling process;
[0014] Figure 2b is a detail view of the MD machine of Figure 1, and
discloses aspects of
the operation of the MD machine relative to a film;
[0015] Figure 2c is another detail view illustrating the formation of
indicia on a portion
of a film, a rib in this case, by a tool such as a ring roller;
[0016] Figure 2d discloses some example cross-sectional rib shapes and
arrangements;
[0017] Figure 3 discloses aspects of an example process for producing an
extruded
multilayer film;
[0018] Figures 4a-1 and 4a-2 depict a first example of a film, referred to
herein as Film
'A', where the film in Figures 4a-1 and 4a-2 is an un-stretched film;
[0019] Figures 4b- 1 and 4b-2 depict a first variation of Film 'A, where
the film has been
ring rolled in the machine direction;
[0020] Figures 4c-1 and 4c-2 disclose another depiction of the first
variation of Film 'A,'
where the film has been ring rolled in the machine direction;
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[0021] Figures 4d-1 and 4d-2 depict of a second variation of Film 'A,'
where the film has
been ring rolled first in the machine direction, and subsequently in the
transverse direction;
[0022] Figures 5a-1 and 5a-2 depict a second example of a film, referred
to herein as
Film 13', where the film in Figures 5a-1 and 5a-2 is an un-stretched film;
[0023] Figures 5b-1 and 5b-2 depict a first variation of Film '13,' where
the film has been
ring rolled in the machine direction;
[0024] Figures 5c-1 and 5c-2 depict a second variation of Film 13,' where
the film has
been ring rolled first in the machine direction, and subsequently in the
transverse direction;
[0025] Figures 6a-1 and 6a-2 depict a third example of a film, referred to
herein as Film
'C,' where the film in Figures 6a-1 and 6a-2 is an un-stretched film;
[0026] Figures 6b-1 and 6b-2 depict a first variation of Film 'C,' where
the film has been
ring-rolled in the machine direction;
[0027] Figures 6c-1 and 6c-2 depict a second variation of Film `C,' where
the film has
been ring rolled first in the machine direction, and subsequently in the
transverse direction;
[0028] Figures 7a-1 and 7a-2 depict a fourth example of a film, referred
to herein as Film
'H,' where the film in Figures 7a-1 and 7a-2 is an un-stretched film;
[0029] Figures 7b-1 and 7b-2 depict a first variation of Film 'FL' where
the film has been
ring rolled in the machine direction; and
[0030] Figures 7c-1 and 7c-2 depict a second variation of Film `H,' where
the film has
first been ring rolled in the machine direction, and subsequently in the
transverse direction.
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DETAILED DESCRIPTION
[0031] Example embodiments of the invention generally concern extruded
films. More
particularly, at least some embodiments are directed to extruded films with
one or more visual
and/or tactile elements perceptible by a user, while other embodiments are
directed to methods
for producing such films. Insofar as such films may, subsequent to their
formation, be employed
in the construction of structures such as discontinuously laminated film
structures, such films
may be referred to herein as precursor films. The films disclosed herein may
be employed in a
variety of different end products, examples of which include, but are not
limited to, grocery bags,
trash bags, sacks, yard waste bags, packaging materials, feminine hygiene
products, baby
diapers, adult incontinence products, sanitary napkins, bandages, food storage
bags, food storage
containers, thermal heat wraps, facial masks, wipes, and hard surface
cleaners.
[0032] A. Aspects of Various Example Embodiments
[0033] It should be noted that the embodiments disclosed herein do not
constitute an
exhaustive summary of all possible embodiments, nor does the following
discussion constitute
an exhaustive list of all aspects of any particular embodiment(s). Rather, the
following
discussion simply presents selected aspects of some example embodiments. It
should likewise
be noted that nothing herein should be construed as constituting an essential
or indispensable
element of any invention or embodiment. Rather, and as the person of ordinary
skill in the art
will readily appreciate, various aspects of the disclosed embodiments may be
combined in a
variety of ways so as to define yet further embodiments. Such further
embodiments are
considered as being within the scope of this disclosure. As well, none of the
embodiments
embraced within the scope of this disclosure should be construed as
necessarily resolving, or
being limited to the resolution of, any particular problem(s). Nor should such
embodiments be
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construed to necessarily implement, or be limited to implementation of, any
particular effect(s).
[0034] Films within the scope of this disclosure may possess or exhibit a
variety of
different physical, visual, and/or optical characteristics. The visual and/or
optical characteristics
may be achieved without the use, for example, of metal layers, color
generating laminates,
delamination, and/or bending of the film structures.
[0035] Illustrative examples of effects such as visual appearances that
may be manifest in
various embodiments of a film include: a coextruded film with a plurality of
layers, including a
ribbed outer layer, where a contrast in color and/or color intensity is
apparent between the ribs
and the webs between the ribs; a film with a ribbed outer layer that includes
a voiding agent; a
film with a ribbed outer layer that includes a stress-sensitive voiding agent;
a film with a ribbed
outer layer lacking a coloring agent, and an inner layer lacking a coloring
agent; a film with an
outer layer having white ribs and colorless webs, and an inner layer lacking a
coloring agent; a
film with an outer layer having black ribs and colorless webs, and an inner
layer lacking a
coloring agent; a film with an outer layer having white ribs and black webs,
and a black inner
layer; and, a coextruded film with an outer layer having black ribs and white
webs, and further
including a white inner layer.
[0036] It should be noted that the aforementioned rib, web, and layer
colors are provided
by way of example. Thus, for example, the inner layer and outer layer need not
be black, or
white, but may include any coloring agent and/or voiding agent capable of
imparting or causing
the appearance of any other color. In general, any color(s) may be used that
provide a visual
contrast between the ribs and webs of a ribbed layer.
[0037] As suggested by the foregoing general considerations, films and
associated
products within the scope of this disclosure may include one or more of the
following, in any
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suitable combination: a core layer with a coloring agent; an core layer
lacking a coloring agent;
a skin layer that includes a voiding agent; an skin layer lacking a coloring
agent; a ribbed skin
layer; a ribbed skin layer containing a voiding agent; a ribbed skin layer
containing a stress-
sensitive voiding agent; a ribbed skin layer including a coloring agent; an
ribbed skin layer
lacking a coloring agent; two or more coextruded layers, where one of the
layers is a core layer,
and one of the layers is a skin layer; two or more coextruded layers, where
one of the layers is a
core layer, and one of the layers is a ribbed skin layer having ribs whose
color contrasts with a
color of webs between the ribs; three or more coextruded layers, wherein two
of the layers are
skin layers and one of the layers is a core layer positioned between the skin
layers; two or more
coextruded layers, where one of the layers is a core layer, and one of the
layers is a ribbed skin
layer; three or more coextruded layers, wherein two of the layers are skin
layers, one of the
layers is a core layer positioned between the skin layers, and one of the skin
layers is ribbed; two
or more coextruded layers, where one of the layers is a core layer, and one of
the layers is a skin
layer, and the core layer and the skin layer lack a coloring agent; an
extruded film with a ribbed
skin layer including one or more of stitches, discontinuous lines, colored
ribs, and, ribs with a
metallic appearance; an extruded film with a ribbed skin layer bearing one or
more indicia of
post-extrusion processing of the extruded film; an extruded film with a ribbed
skin layer bearing
one or more indicia of post-extrusion ring rolling of the extruded film; an
extruded film with a
ribbed skin layer including one or more visual and/or tactile elements at
least partly resulting
from post-extrusion processing; an extruded film with a ribbed skin layer
including one or more
visual and/or tactile elements at least partly resulting from post-extrusion
processing, the visual
and/or tactile elements including one or more of stitches, discontinuous
lines, colored ribs, and,
ribs with a metallic appearance; an extruded film with a ribbed skin layer
including one or more
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visual and/or tactile elements produced at least in part by one or both of MD
ring rolling and TD
ring rolling, and the visual and/or tactile elements including one or more of
stitches,
discontinuous lines, colored ribs, and, ribs with a metallic appearance, and,
an end product
including any of the foregoing layers, or combinations of those layers.
[0038] It will be appreciated from the foregoing, and the other disclosure
herein, that a
variety of different embodiments may be defined. Some examples of such
embodiments are set
forth below. Such embodiments are not intended to limit the scope of the
invention in any way.
[0039] In a first example embodiment, an extruded multilayer film includes
a ribbed skin
layer having ribs connected by webs, where the webs and ribs are integral with
each other.
[0040] In a second example embodiment, an extruded multilayer film includes
a ribbed
skin layer, and a core layer.
[0041] In a third example embodiment, an extruded multilayer film includes
a core layer
and a pair of skin layers, where one or both of the skin layers are ribbed.
[0042] In a fourth example embodiment, an extruded multilayer film includes
a core
layer, and a ribbed skin layer that includes a voiding agent.
[0043] In a fifth example embodiment, an extruded multilayer film includes
a core layer
that includes a coloring agent, and a ribbed skin layer that includes a
voiding agent.
[0044] In a sixth example embodiment, an extruded multilayer film includes
a core layer,
and a ribbed skin layer that includes a stress-sensitive voiding agent.
[0045] In a seventh example embodiment, an extruded multilayer film
includes a core
layer and a ribbed skin layer, where the ribs of the ribbed skin layer
contrast with webs between
the ribs in terms of one or both of color, and color intensity.
[0046] In an eighth example embodiment, an extruded multilayer film
includes a core
CA 2903554 2019-03-13
layer and a ribbed skin layer, where the ribs of the ribbed skin layer include
a voiding agent, and
webs between the ribs are substantially colorless.
[0047] In a ninth example embodiment, an extruded multilayer film includes
a core layer
and a ribbed skin layer, where the core layer is one of colorless or black,
and the ribbed skin
layer is one of colorless or white.
[0048] In a tenth example embodiment, an extruded multilayer film
including a ribbed
skin layer bears one or more indicia of post-extrusion processing, the one or
more indicia being
perceptible by one or more senses of a user.
[0049] In an eleventh example embodiment, an extruded multilayer film
including a
ribbed skin layer bears one or more indicia of post-extrusion processing,
where the post-
extrusion processing is one or both of MD ring rolling, and TD ring rolling.
[0050] In a twelfth example embodiment, an extruded multilayer film
including a ribbed
skin layer bears one or more indicia of post-extrusion processing, where the
indicia are present
on the ribs of the ribbed skin layer.
[0051] In a thirteenth example embodiment, an extruded multilayer film
including a
ribbed skin layer bears one or more indicia of post-extrusion processing, and
the indicia
comprise one or more of a visible deformation of a rib, a color of a rib, and
a color of a web.
[0052] In a fourteenth example embodiment, an extruded multilayer film
including a
ribbed skin layer bears one or more indicia of post-extrusion processing,
where the indicia
convey information concerning a relative strength of the film.
[0053] In a fifteenth example embodiment, an extruded multilayer film
including a
ribbed skin layer bears one or more indicia of post-extrusion processing,
where the indicia
indicate the imposition of stress and/or strain on the ribs of the ribbed skin
layer.
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[0054] In a
sixteenth example embodiment, a process to form an extruded multilayer film
includes coextruding a ribbed outer layer together with a core layer.
[0055] In a
seventeenth example embodiment, a process to form an extruded multilayer
film includes coextruding a ribbed outer layer together with a core layer, and
subjecting the
extruded multilayer film to post-extrusion processing including one or both of
MD ring rolling
and TD ring rolling, performed in any order.
[0056] In an
eighteenth example embodiment, a process to form an extruded multilayer
film includes adding a coloring agent to one or both of a ribbed outer layer
and a core layer, and
coextruding the ribbed outer layer together with the core layer.
[0057] In a
nineteenth example embodiment, a process to form an extruded multilayer
film includes coextruding a ribbed outer layer together with a core layer,
where the ribbed outer
layer includes a voiding agent.
[0058] In a
twentieth example embodiment, a process to form an extruded multilayer
film includes adding a voiding agent to a ribbed outer layer and adding a
coloring agent to a core
layer, coextruding the ribbed outer layer together with the core layer, and
subjecting the extruded
multilayer film to post-extrusion processing including one or both of MD ring
rolling and TD
ring rolling, performed in any order.
[0059] In a
twenty first example embodiment, a process to form an extruded multilayer
film includes coextruding a ribbed outer layer together with a core layer,
where the core layer
lacks a coloring agent and the ribbed outer layer includes a voiding agent,
and subjecting the
extruded multilayer film to post-extrusion processing including one or both of
MD ring rolling
and TD ring rolling, performed in any order.
[0060] In a
twenty second example embodiment, a process to form an extruded
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multilayer film includes coextruding a ribbed outer layer together with a core
layer, and
producing one or more indicia in the extruded multilayer film by subjecting
the extruded
multilayer film to post-extrusion processing including one or both of MD ring
rolling and TD
ring rolling, performed in any order.
[0061] In a twenty third example embodiment, a process to form an extruded
multilayer
film includes adding a coloring agent to a core layer, coextruding the ribbed
outer layer together
with the core layer, and producing one or more indicia in the extruded
multilayer film by
subjecting the extruded multilayer film to post-extrusion processing including
one or both of MD
ring rolling and TD ring rolling, performed in any order.
[0062] In a twenty fourth example embodiment, a process to form an
extruded
multilayer film includes coextruding a ribbed outer layer together with a core
layer, where the
ribbed outer layer includes a voiding agent and the core layer lacks a
coloring agent, and
producing one or more indicia in the extruded multilayer film by subjecting
the extruded
multilayer film to post-extrusion processing including one or both of MD ring
rolling and TD
ring rolling, performed in any order.
[0063] In twenty fifth example embodiment, a process to form an extruded
multilayer
film includes coextruding a ribbed outer layer together with a core layer, and
subjecting the
extruded multilayer film to post-extrusion processing including one or both of
MD ring rolling
and TD ring rolling, performed in any order, and the resulting extruded
multilayer film exhibits a
contrast in color and/or color intensity between the ribs and one or both of
the webs and the core
layer.
[0064] In further example embodiments, any of the aforementioned extruded
multilayer
films comprises one or more layers of LLDPE.
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[0065] In further example embodiments, a discontinuously laminated film
structure
includes any of the aforementioned extruded multilayer films.
[0066] In further example embodiments, an end product includes any of the
aforementioned extruded multilayer films or discontinuously laminated film
structures.
[0067] In further example embodiments, any of the aforementioned processes
used in
whole or in part to produce an end product that includes any of the
aforementioned films and/or
discontinuously laminated film structures.
[0068] For purposes of this disclosure and claims, the term "rib" embraces
a portion of
extra resin on a surface of a given precursor film, which portion is an
integral portion of the film,
and before any subsequent hot or cold forming process on the film, such as a
ring rolling process.
The "rib." e.g., reference 251 in Figure 2a of a ribbed film, e.g., reference
250 in Figure 2a, may
be formed in accordance with implementations of the present invention via
extrusion of molten
resin through an appropriate die having one or more sets of grooves for
forming corresponding
ribs. Similarly, for purposes of this description and claims, a -ribbed film"
refers to a film that
has been extruded in molten form with one or more ribs, and therefore
comprises the one or more
extruded ribs independent of any other striations or rib-like formations that
may occur via any
other hot or cold forming, process after the initial extrusion/formation of
the rib(s) of the ribbed
film. Such other striations or rib-like formations from subsequent forming
processes are referred
to herein generally as -Tipple(s)." See, for example, reference 258 of Figures
2a and 2b.
[0069] In terms of the physical configuration of a "rib," the scope of the
invention is not
limited to any particular form, size or orientation thereof. In general
however, the ribs extend
outwardly a distance from a surface of the film. In this structure, a web is
defined between
consecutive ribs. The ribs may or may not have a generally triangular cross-
section, but it will
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be appreciated that, for example, an extrusion die can be configured to
produce a rib having any
desired cross-sectional shape.
[0070] B. Extruded Multilayer Films
[0071] As contemplated herein, multilayer films and extrusion processes for
creating
multilayer films embrace, among other things, coextnision of two or more
layers of resin through
a heated die. Post-extrusion processing of the multilayer films may include,
for example, ring
rolling on one Or both of the machine direction (MD), and the transverse
direction (TD) which is
generally orthogonal to the MD. As used herein, the term "machine direction"
or "MD" refers to
the direction along the length of the film, or in other words, the direction
of the film as the film is
formed during extrusion and/or coating. Likewise, the term "transverse
direction" or "TD"
refers to the direction across the film or perpendicular to the machine
direction. Further, the term
"diagonal direction" or "DD" refers to the direction that is not aligned with
either the length or
the width of the film. Finally, a "coextruded" film refers to a film having
two or more layers that
have been coextruded with each other.
[0072] C. Example Film Materials
[0073] The films disclosed herein may comprise any flexible or pliable
material,
including thermoplastic materials that can be formed or drawn into a film. As
described above,
at least some films within the scope of the invention include a plurality of
layers, one or more of
which may be thermoplastic. Adjuncts may also be included in the film layers,
as desired.
Examples of such adjuncts include slip agents, anti-block agents, tackifiers,
coloring agents such
as pigments, dyes, dilute pigments, voiding agents, and combinations of the
foregoing adjuncts.
[0074] The thermoplastic material of the films of one or more
implementations can
include, but are not limited to, thermoplastic polyolefins, including
polyethylene, polypropylene,
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and copolymers thereof. Besides ethylene and propylene, exemplary copolymer
olefins include,
but are not limited to, ethylene vinylacetate (EVA), ethylene methyl acrylate
(EMA) and
ethylene acrylic acid (EAA), or blends of such olefins.
[0075] Other examples of polymers suitable for use as films in accordance
with the
present invention include elastomeric polymers. Suitable elastomeric polymers
may also be
biodegradable or environmentally degradable. Suitable elastomeric polymers for
the film
include poly(ethylene-butene), poly(ethylene-hexene), poly(ethylene-octene),
poly(ethylene-
propylene), poly(styrene-butadiene-styrene), poly(styrene-isoprene-styrene),
poly(styrene-
ethylene-butylene-styrene), poly(ester-ether), poly(ether-amide),
poly(ethylene-vinylacetate),
poly(ethylene-methylacrylate), poly(ethylene-acrylic acid), poly(ethylene
butylacrylate),
polyurethane, poly(ethylene-propylene-diene), ethylene-propylene rubber, and
combinations of
the foregoing.
[0076] D. General Aspects of Some Example Production Processes
[0077] Consistent with the varied natures of films, various processes, and
combinations
thereof, may be used in the production of the films disclosed herein. Examples
of such processes
include, but are not limited to, extrusion, heat bonding, ultrasonic bonding,
adhesive bonding,
incremental stretching, pressure bonding techniques such as machine direction
(MD) ring rolling,
transverse direction (TD) ring rolling, diagonal direction (DD) ring rolling,
and any ring rolling
process that results in the formation of a laminated film with strainable
networks. Treatment
with a corona discharge may be used to enhance any of the aforementioned
methods.
[0078] More generally however, any other process(es) that produces
multilayer films,
may be employed, and the scope of the invention is not limited to any
particular production
process(es).
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[0079] Consistent with this disclosure, manufacturers may form individual
films to be
coextruded together so as to provide improved strength characteristics using a
wide variety of
techniques. For example, a manufacturer can form a precursor mix of the
thermoplastic material
including any optional additives. The manufacturer can then form the film(s)
from the precursor
mix using conventional flat extrusion, cast extrusion, or coextrusion to
produce monolayer,
coextruded bilayer, or multilayered films. Alternative to conventional flat
extrusion or cast
extrusion processes, a manufacturer can form the films using other suitable
processes, such as, a
blown film process to produce monolayer, bilayer, or multilayered films, which
are subsequently
discontinuously laminated with another film layer at a later stage. If desired
for a given end use,
the manufacturer can orient the films by trapped bubble, tenterframe, or other
suitable processes.
Additionally, the manufacturer can optionally anneal the films.
[0080] Where extrusion is employed, a manufacturer can use multiple
extruders to supply
different melt streams, which a feed block can order into different channels
of a multi-channel
die. The multiple extruders can allow a manufacturer to form a multi-layered
film with layers
having different compositions. Such multi-layer film may later be
discontinuously laminated
with another layer of film, which may or may not be multi-layer itself, to
provide a
discontinuously laminated film structure.
[0081] In a blown film process, the die can be an upright cylinder with a
circular
opening, and the die may include geometric features about its inner surface
that can form various
structures on the film as the molten plastic is extruded through the die. As
disclosed elsewhere
herein, one example of such a geometric feature is a set of teeth disposed
about the inner surface
of the die which may cause the formation of ribs on the film as the molten
plastic is passed
17
CA 2903554 2019-03-13
through the die. One example of such a die is disclosed in Figure 1 and
discussed in more detail
below.
[0082] With continuing reference to the blown film process, rollers can
pull molten
plastic upward away from the die. An air-ring can cool the film as the film
travels upwards. An
air outlet can force compressed air into the center of the extruded circular
profile, creating a
bubble. The air can expand the extruded circular cross section by a multiple
of the die diameter.
This ratio may be referred to as the "blow-up ratio," or BUR. When using a
blown film process,
the manufacturer can collapse the film to double the plies of the film.
Alternatively, the
manufacturer can cut and fold the film, or cut and leave the film unfolded.
[0083] A more detailed discussion of various specific examples of
production processes
that may be used in the production of the films disclosed herein is set forth
elsewhere herein.
[0084] E. Example Production Equipment
[0085] Directing attention first to Figure 1, details are provided
concerning aspects of a
machine 50 that may be used to form coextruded multilayer films such as those
disclosed herein.
As the general aspects of the operation of such a machine and its operation
have been set forth
elsewhere herein, the following description is primarily concerned with a
machine and process
for extruding a multilayer film that includes ribs on at least one layer.
[0086] Briefly, the machine 50 may include one or more dies, such as die
52, configured
to receive a stream of molten plastic. The die 52 defines an annulus 54
through which the
molten plastic is passed, or extruded. The annulus 54 may be substantially
circular in shape, but
that is not required and annuluses 54 having other shapes may be employed.
Where the annulus
54 is substantially circular in shape, the annulus 54 defines an inner
diameter 56 having a size
that can be selected depending upon the requirements of a particular
application. In some
18
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instances, the inner surface 58 of the annulus 54 can be substantially smooth
and free of any
discontinuities or other geometric features, and the same may likewise be true
of the outer
surface (this example not shown) of the annulus 54, although that is not
necessary. In this
example, the die 52 may produce a film layer that has a substantially smooth
outer surface.
[0087] In other instances however, the inner surface 58 of the annulus 54
may be
substantially smooth and free of any discontinuities or other geometric
features, while the outer
surface 59 of the annulus 54 may include one or more elements 60 configured
and arranged such
that as the molten plastic passes through the die 52, the outer surface of the
extruded film layer
assumes a structure and appearance that corresponds with the configuration and
arrangement of
the elements 60 of the outer surface 59. In the example of Figure 1, the
elements 60 comprise
grooves having a substantially U-shaped configuration, and the elements 60 are
substantially
evenly spaced about the outer surface 59 so that an extruded film produced by
the die 52
includes a ribbed outer surface having ribs extending, for example, in the
machine direction,
though ribs oriented in other directions may also be produced. In general, the
configuration of
the ribbed outer surface will reflect the size, number, shape, and spacing of
the elements 60.
Where the elements 60 comprise grooves, the grooves may have sharp or rounded
bottoms and
can all be substantially the same size, or different sizes.
[0088] While the elements 60 in the example of Figure I comprise grooves,
the elements
60 can have any other desired structure. Accordingly, the scope of the
invention is not limited to
ribbed, extruded films having an outer surface structure and appearance that
corresponds to the
example die 52 of Figure 1. Further, while the example annulus 54 indicated in
Figure 1
includes a substantially smooth inner surface and a ribbed outer surface, it
will be appreciated
that various types of annuluses, or functionally comparable structures, can be
employed to
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CA 2903554 2019-03-13
produce films with particular characteristics, and the scope of the invention
is not limited to films
such as may be produced by the annulus 54. To illustrate, an annulus may be
employed that
includes elements 60, such as ribs for example, on both its inner and outer
surfaces, so as to
produce a film that is ribbed on both sides. As another example, an annulus
may be employed
that includes elements 60 on its inner surface, but not on its outer surface,
so as to produce a film
with an outer surface that is relatively smooth and an inner surface that
includes features
produced by elements 60, such as ribs for example.
[0089] With reference now to Figures 2a and 2b, details are provided
concerning aspects
of a machine 150 that may be employed in the post-extrusion processing of a
film, such as film
250 for example, to produce one or more of the ribbed films disclosed herein.
[0090] With regard initially to a film, the example film 250 may be an
extruded,
multilayer precursor film and may comprise any of the materials disclosed
herein. For example,
the film 250 may comprise two or more layers, such as a core layer positioned
between two skin
layers. Such a film 250 may be formed in whole or in part, by extrusion, for
example.
Moreover, at least one of the skin layers may include ribs 251 formed by the
extrusion process,
that is, extruded ribs. As indicated in Figure 2a, the ribs 251 may extend
generally parallel to the
machine direction, but that is not required. A film 250 that has not been
subjected to post-
extrusion processing, and which has at least one layer that includes such ribs
251, may be
referred to herein as a ribbed precursor film.
[0091] In any case, the film 250 can have an initial thickness or starting
gauge 252
defined by the distances between its top 254 and bottom surfaces 256. In at
least one
embodiment, the starting gauge 252, as well as the respective gauges of the
individual layers can
be substantially uniform along the length of the film 250.
CA 2903554 2019-03-13
[0092] With regard now to the machine 150, Figures 2a and 2b disclose
portions of a
machine 150 that can implement an MD ring rolling process that may impart
indicia to the film
250 and/or cause the appearance of indicia on the film 250. It should be noted
that an MD ring
rolling process is one particular example of an MD stretching process. Other
processes besides
MD ring rolling can be used to effect MD stretching. As discussed in further
detail below, such
indicia may include, for example, stars, dots, discontinuities, stitches, and
any other physical
and/or visual indicia that may result from the MD processing of the film 250.
More specifically,
such indicia may include indicia that results from the physical contact
between the MD machine
and/or other post-extrusion processing machines and portions of the film 250,
such as the ribs
251, and such indicia may additionally, or alternatively, include color,
intensified color, and
other effects that result from the stretching of the film 250, such as by the
machine 150.
[0093] In the example of Figures 2a and 2b, the machine 150 includes a pair
of MD
intermeshing rollers 152 and 154 through which the film 250 is passed. As a
result of MD ring
rolling, the film 250 is intermittently stretched in the machine direction MD,
and/or portions of
the film 250 such as the ribs 251 for example, may be subjected to stress
and/or strain due to
physical contact between those portions of the film 250 and machine 150
elements such as the
rollers 152 and/or 154.
[0094] With regard to their configuration, Figure 2a discloses that the
first roller 152 and
the second roller 154 can each have a generally cylindrical shape, and are
operable to rotate in
opposite directions about respective parallel axes of rotation 152a and 154a
that may be
generally parallel to the transverse direction TD and generally perpendicular
to the machine
direction MD. The rollers 152 and 154 each include a respective plurality of
radially protruding
ridges 156 and 158 that extend along the respective rollers 152 and 154 in a
direction generally
21
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=
parallel to the axes of rotation 152a and 154a. The respective tips 156a and
158a of ridges 156
and 158 can have a variety of different shapes and configurations, including
the rounded shape as
shown in Figure 2b. In alternative implementations, the tips 156a and 158a of
the ridges 156 and
158 can have sharp angled corners. As further indicated in Figures 2a and 2b,
the ridges 156 are
separated by grooves 160, while the ridges 158 are separated by grooves 162.
[0095] The ridges 156 and 158 are staggered relative to each other so
that the grooves
160 can receive at least a portion of the ridges 158 as the rollers 152 and
154 intermesh with
each other. Correspondingly, the grooves 162 can receive at least a portion of
the ridges 156. In
at least some instances, the configuration of the ridges 156 and 158 and
grooves 160 and 162 can
prevent substantial contact between ridges 156 and 158 during intermeshing
such that little or no
rotational torque is transmitted during operation. Additionally, the
configuration of the ridges
156 and 158, and of the grooves 160 and 162 can affect the amount of
stretching of the film 250
as it passes through the rollers 152 and 154.
[0096] With continued reference to Figures 2a and 2b, the pitch and depth
of engagement
of the ridges 156 and 158 can determine, at least in part, the amount of
incremental stretching
caused by the intermeshing rollers 152 and 154. As shown in Figure 2b, the
pitch 164 is the
distance between the tips of two adjacent ridges on the same roller. The depth
of engagement
(DOE) 166 is the amount of overlap between adjacent ridges 156 and 158 of the
rollers 152 and
154 during intermeshing.
[0097] As is evident from the foregoing, various parameters of the
machine 150 may be
selected and implemented depending upon the effect(s) desired to be achieved.
For example, the
ridge pitch and/or DOE may be varied as necessary. Merely because these
parameters, and
others, may be varied however, such variations will not necessarily be evident
to one of ordinary
22
CA 2903554 2019-03-13
skill in the art, and may, in some instances at least, be arrived at only
after substantial
experimentation and trials.
[0098] As indicated in Figures 2a and 2b, the direction of travel of the
film 250 through
the intermeshing rollers 152 and 154 is generally parallel to the machine
direction and generally
perpendicular to the transverse direction. As the film 250 passes between the
intermeshing
rollers 152 and 154, the ridges 156 and 158 incrementally stretch the film 250
in the machine
direction. In one or more implementations, stretching the film 250 in the
machine direction can
reduce the gauge of the film and increase the length of the film 250. In other
implementations,
the film 250 may rebound after stretching such that the gauge of the film 250
is not substantially
decreased. Furthermore, in one or more implementations, stretching the film
250 in the machine
direction can reduce the width of the film 250. For example, as the film 250
is lengthened in the
machine direction, the width of the film 250 can be reduced in the transverse
direction.
[0099] In particular, and as best shown in Figure 2b, as the film 250
proceeds between
the intermeshing rollers 152 and 154, the ridges 156 of the first roller 152
can push film 250 into
the grooves 162 of the second roller 154, and the ridges 158 of the second
roller 154 can also
push the film 250 into the grooves 160 of the first roller 152. The pulling of
the film 250 by the
ridges 156 and 158 can stretch the film 250. However, the rollers 152 and 154
need not
necessarily stretch the film 250 evenly along its length. Specifically, the
rollers 152 and 154 can
stretch the portions of the film 250 between the ridges 156 and 158 more than
the portions of the
film 250 that contact the ridges 156 and 158, as indicated in Figure 2b.
[00100] Thus, the rollers 152 and 154 can cooperate to form a series of
machined ripples
258 in the film 250 such that the film 250 includes relatively thicker
portions alternating with
relatively thinner portions. As indicated in Figure 2a, the ripples 258 in
this particular example
23
CA 2903554 2019-03-13
are disposed generally parallel to the transverse direction. In this example
then, the ripples 258
are generally orthogonal to the ribs 251, but such an arrangement is not
required. Thus, the
finished film 250 may be a rippled film of multi-layer, or single layer,
construction. As
disclosed elsewhere herein, various desirable visual effects and
characteristics may be achieved
through selection and processing of various films that make up a multi-layer
implementation of
the film 250.
[00101] Directing attention now to Figure 2c, and with continuing attention
to Figures 2a
and 2b, details are provided concerning aspects of an example machine and
process which may
be useful in creating various indicia on a film layer, such as a ribbed film
layer for example. In
particular, it can be seen that when an MD ring rolling process, for example,
is performed on the
example film 250 (see Figures 2a and 2b), the ridges 156 and 158 may
temporarily or
permanently compress portions of the ribs 251. The compressions 260 may, but
need not, be
generally orthogonal to the direction of the ribs 251.
[00102] It will be appreciated that the compressions 260 of the ribs 251
constitute one
example of indicia, discussed in more detail elsewhere herein. The color,
size, number,
geometry and orientation of the compressions 260 may depend on one or more of
the particular
ring rolling process performed, roller pitch, DOE, material(s) of the film,
and coloring agents
such as pigments and/or voiding agents present in one or more film layers.
[00103] MD ring rolling is one example of method suitable to impart indicia
to a film,
such as a multi-layer film for example, by incremental stretching of the film
in the machine
direction. TD ring rolling is another suitable method of imparting indicia to
a film such as a
multi-layer film for example, by incremental stretching of the film in the
transverse direction.
TD ring rolling, like MD ring rolling, may be used alone or in conjunction
with other processes.
24
CA 2903554 2019-03-13
While not specifically illustrated, a TD ring rolling machine and associated
process may be
similar, respectively, to the MD ring rolling machine and associated process,
though the rollers
of a TD ring rolling machine include ridges and grooves that extend generally
parallel to the MD
direction, rather than orthogonal to the MD direction, as in the case of an MD
machine and
process. Thus, a TD ring rolling process may produce a rippled film having
ripples that are
generally parallel to the MD direction, Similar to the case of MD ring
rolling, it should be noted
that a TD ring rolling process is one particular example of a TD stretching
process. Other
processes besides TD ring rolling can be used to effect TD stretching.
[00104] Finally, Figure 2d discloses some example cross-sectional element
60a, 60b and
60c shapes, such as rib shapes, and element combinations 60d, 60e, 60f and 60g
which can be
employed on the inner and/or outer layers of a film. As indicated in Figure
2d, where the
elements are employed on inner and outer layers, the elements on opposing
sides of the film can
be substantially aligned with each other, or staggered relative to each other.
It should be noted
that the scope of the invention is not limited to those shapes. Moreover,
different sizes and
configurations of ribs can be combined in a single film.
[00105] E. Example Processes for Creating Films
[00106] It was noted earlier that formation of embodiments of the invention
may include
the use of an extrusion process. Directing attention now to Figure 3, details
are provided
concerning an example process 300 that may be employed in the production of
films, such as the
example films noted herein. It should be noted that while Figure 3 refers to
the use of voiding
agents, any suitable type of coloring agent may alternatively be employed in
connection with one
or more of the processes set forth in that Figure.
[00107] E.1 Coex trusion
CA 2903554 2019-03-13
[00108] The example process 300 begins at 302 where a core layer resin and
a skin layer
resin are prepared. This may involve preparing blends for the skin and/or core
layers in
preparation for an extrusion process. In at least some embodiments, a skin
layer blend is
prepared that will be used for one or more skin layers. The blend may comprise
LLDPE or any
other plastic material(s) disclosed herein.
[001091 At 304, a voiding agent is added to at least one of the skin layer
blend and the
core layer blend. In some embodiments, the voiding agent(s) is/are added only
to the skin layer
resin. The voiding agent may be added prior to, during, or after, melting of
the layer resin. The
voiding agent may be in various forms, examples of which include dry powder
form, and
solution. As discussed in more detail below, the voiding agent may be
colorless, translucent,
white, or any other color. In at least some cases, the voiding agent may
comprise calcium
carbonate (CaCO3). However, as noted elsewhere herein, other suitable voiding
agent(s), and
combinations thereof, can alternatively be employed.
1001101 In a least some instances, calcium carbonate is but one example,
the voiding agent
may be stress-sensitive. As such, the voiding agent may appear to be
substantially colorless in,
for example, an un-stretched, or otherwise unstressed, film. However, stress
and/or strain
imposed on the film including the coloring agent may cause film elements, such
as ribs for
example, that include the voiding agent to change color. One or more examples
of such a film
are disclosed elsewhere herein. In other instances, a voiding agent itself may
be colorless or
substantially so, but stress or strain applied to voids created by a voiding
agent may cause the
resin in the vicinity of the voids to change color.
[00111] After the voiding agent has been added to the blend, the process
300 moves to 306
where the skin layer resin and core layer resin are coextruded to form an
extruded multilayer
26
CA 2903554 2019-03-13
film. As noted elsewhere herein, at least some embodiments provide for the use
of a die that
includes elements which cause the formation of ribs on the skin layer as the
skin layer resin is
extruded through the die.
[00112] After coextrusion 306, the resulting extruded multilayer film may
be subjected to
various types of post-extrusion processing 308. In some instances, such as in
the example of
Figure 3, the post-extrusion processing takes place prior to lamination of the
extruded multilayer
film with any other films. In other instances, the post-extrusion processing
is performed during,
or after, the lamination of the extruded multilayer film with one or more
other films. More
generally, one or more post-extrusion processes may be performed at any, or
all, of the
aforementioned junctures. Accordingly, the scope of the invention is not
limited to any
particular post-extrusion process, or combination of processes, nor is the
scope of the invention
limited to performance of the post-extrusion processes at any particular
juncture(s) after
formation of the extruded multilayer film.
[00113] With continued reference to Figure 3, the post-extrusion processing
may include
stretching, examples of which include one or more of MD ring rolling and TD
ring rolling,
performed in any order. In some example embodiments, the MD ring rolling is
performed prior
to the TD ring rolling, but that is not necessary. In yet other example
embodiments, only MD
ring rolling is performed. More generally, one or more post-extrusion
processes may comprise
incremental stretching or other plastic and/or elastic deformation of the
extruded, ribbed
multilayer film in one or more directions simultaneously, or serially.
[00114] As disclosed elsewhere herein, the post-extrusion processing of the
extruded,
ribbed multilayer film may result in the formation of various types of indicia
in and/or on the
ribbed skin layer and/or elsewhere in the extruded, ribbed multilayer film.
27
CA 2903554 2019-03-13
[00115] E.2 Voiding Agents
[00116] As noted earlier, at least some of the processes that may be
employed to create the
films disclosed herein generally involve the coextrusion of two or more film
layers to form a
coextruded multilayer film. Consistent with the embodiments disclosed herein,
one or more
coloring agents, such as voiding agents for example, may be added to one or
more film resins
prior to coextrusion of a multilayer film. In general, voiding agents include,
among other things,
any material, or combination of materials, that serve to create, or facilitate
the creation of, voids
in a resin or other material in which the voiding agent is dispersed. Thus, a
film in which a
voiding agent has been dispersed may include voids disposed, uniformly or
otherwise,
throughout the film. The presence and concentration of such voids can have a
variety of effects
on the appearance of the associated film.
[00117] For example, relatively thicker portions of the film may include
relatively more
voids than thinner portions of the film. Thus, the thicker portions of the
film may contrast
visibly in terms of color and/or color intensity with the thinner portions of
the film. As another
example, thicker and thinner portions of the film may react differently to the
imposition of
stresses. This can be due to the relatively different physical structures of
those portions, namely,
the thicker portion includes more voids than the thinner portion, such that
imposition of stress
may, as noted in some examples herein, cause thicker portions such as ribs to
change color
and/or to become more intense in color, while thinner portions may be less
affected in terms of
their color and/or color intensity. Thus, a voiding agent introduced into a
material can cause one
or more colors to be imparted to that material, by various mechanisms,
notwithstanding that the
voiding agent itself may have little or no intrinsic color. In other
instances, a voiding agent may
28
CA 2903554 2019-03-13
have an intrinsic color that may affect the appearance of a film into which
the voiding agent is
introduced.
[00118] Some examples of voiding agents that may be employed in connection
with
various embodiments of the invention include, but are not limited to, calcium
carbonate,
magnesium carbonate, barium carbonate, calcium sulfate, magnesium sulfate,
barium sulfate,
calcium oxide, magnesium oxide, titanium oxide, zinc oxide, aluminum
hydroxide, magnesium
hydroxide, talc, clay, silica, alumina, mica, glass powder, starch, and any
combination of the
foregoing. Organic voiding agents, one example of which is polystyrene, may
also be used in
connection with various embodiments of the invention. At least some of these
voiding agents,
such as calcium carbonate for example, may have an intrinsic color, such as
white, that will be
manifest in a film that employs the voiding agent.
[00119] It was noted earlier that in one particular example, a suitable
voiding agent
comprises calcium carbonate. In general, the concentration of the voiding
agent can be varied
depending, for example, upon variables such as the layer in which a
masterbatch is to be used,
the material of the layer in which the voiding agent or masterbatch is to be
employed, a color
and/or concentration of the masterbatch, and the presence, or not, of other
coloring agents in the
resins that are used to form the other layers of an extruded multilayer film.
Accordingly, the
scope of the invention is not limited to any particular concentration, or
range(s) of concentration,
of the voiding agent.
[00120] In one specific example however, a calcium carbonate voiding agent
concentration in a range of about 5 percent to about 25 percent has been found
useful in some
embodiments of a skin layer. Further, a concentration of the calcium carbonate
voiding agent of
about 15 percent has been found to be particularly useful in some embodiments
of the skin layer.
29
CA 2903554 2019-03-13
=
[00121] Finally, it should be noted that in certain circumstances, the
concentration of the
voiding agent in a layer may be a function of rib thickness, Or the thickness
of other elements of
a layer or film, such that relatively thicker ribs may permit the user of a
relatively lower
concentration of voiding agent. This may be advantageous inasmuch as
relatively thicker ribs
may enable an overall reduction in cost by reducing the amount of voiding
agent required.
Further, relatively thicker ribs contribute to an overall increase of a layer
and film in which the
ribs are employed. Correspondingly, excessive voiding agent concentrations can
negatively
affect the structural integrity of a film. Thus, the need for the useful
effects that a voiding agent
can provide may need to be balanced with negative effects that may attend
excessive
concentrations of the voiding agent.
[00122] F. Example Films
[00123] In general, and within the scope of this disclosure, there are a
variety of films that
may be produced and, accordingly, it should be understood that the embodiments
of films set
forth in the Figures, and discussed herein, are presented solely by way of
illustration and are not
intended to limit the scope of the invention in any way. The example films
discussed below are
extruded, ribbed films that may be produced in a variety of different ways,
including the example
extrusion, and other, processes noted above.
[00124] In addition to a visually appealing appearance, such ribs may
provide a structure
that deforms, thereby producing indicia, when subjected to various ring
rolling (RR) processes,
such as DD, MD, and/or TD ring rolling. As noted elsewhere herein, variables
such as pitch of
ribs, DOE, and/or RR teeth can be adjusted to provide desirable visual effects
in the film.
[00125] F,1 Example Film 'A'
CA 2903554 2019-03-13
[00126] Figures 4a-1 through 4d-2 and the corresponding text provide
details concerning
an example ribbed film laminate structure referred to herein as Film 'A.' In
this particular
example, Film 'A' is an extruded film that comprises three layers of linear
low-density
polyethylene (LLDPE), having a layer structure of A:B:A, wherein the layer
ratio for the three
layers is about 20:60:20. That is, the outer two layers, or skin layers, each
have a thickness of
about 20 percent of the total thickness of Film 'A', while the core layer has
a thickness of about
60 percent of the total thickness of Film 'A'.
[00127] Figures 4a-1 through 4d-2 further show that both the core layer and
the skin layers
are un-pigmented. In Figures 4a-1, 4b-1, 4c-1 and 4d-1, the left-side portion
of the film is shown
on a white background, and the right-side portion of the film is shown on a
black background, to
better disclose various aspects of the film. The same is likewise true of
Figures 5a-1, 5b-1, 5c-1,
6a-1, 6b-1 and 6c-1. In Figures 7a-1, 7b-1 and 7c-1, only a black background
is used.
[00128] The ribs of Film 'A' averaged about 6.5 mils tall, with an average
spacing
between extruded ribs 403 of about 0.336 inches. The thickness of the web 405
between
consecutive extruded ribs 403 was targeted to be about 0.50 mils thick. As
indicated in the
Figures, the extruded ribs 403 appear translucent as a result of their
relative thickness, and as a
result of its thinness, the web 405 between the extruded ribs 403 appears to
be nearly colorless.
[00129] With particular reference first to Figures 4a-1 and 4a-2, an
embodiment of Film
'A' is disclosed that reflects an absence of post-extrusion processing, such
as MD or TD ring
rolling. As illustrated, the ribs 403 have a hazy appearance, and the web 405
between the ribs
403 is largely translucent.
[00130] Figures 4b-1, 4b-2, 4c-1 and 4c-2 further disclose that different
effects can be
achieved in, for example, the appearance and/or feel of a ribbed film by
varying the post-
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CA 2903554 2019-03-13
extrusion tools and/or processing employed in connection with the film. Such
tools and/or
processing can include one or more of DOE, tooth pitch, tooth shape, and ring
rolling including
one or more of TD, MD and DD ring rolling. To illustrate, Figures 4b-1, 4b-2,
4c-1 and 4c-2
disclose an implementation in which Film 'A' was stretched by an MD process
using a 200 pitch
tool and a DOE of about 150 mils. MD stretching with these parameters resulted
in the web 405
having a hazier appearance, relative to the un-stretched embodiment of Figures
4a-1 and 4a-2,
while the ribs 403 experienced no substantial change in color or haze. This is
particularly
apparent when referring to the right hand side of Figures 4a-1 and 4b-1, where
Film 'A' is
disposed on a black background. In Figure 4c-1, in particular, it can be seen
that the MD
stretching produced a number dots or stars 407 in the ribs 403.
[00131] Figures 4d-1 and 4d-2 disclose the embodiment of Figures 4b-1, 4b-
2, 4c-1 and
4c-2 after that embodiment was further subjected to a TD ring rolling process
with a 40 pitch
tool and DOE of about 20 mils. The additional TD ring rolling process produced
no substantial
change in the haze of the web 405 between the ribs 403. Similarly, this
process produced no
substantial color change in the extruded ribs 403 or web 405 between the
extruded ribs 403.
[00132] F.2 Example Film 13'
[00133] Figures 5a-1 and 5a-2 discloses aspect of another film referred to
herein as Film
'B,' before any ring rolling, such as TD or MD ring rolling, has been
performed. Similar to Film
'A,' Film 'B' is an extruded, ribbed film laminate structure that comprises
three layers of linear
low-density polyethylene (LLDPE) having a layer structure of A:B:A, where the
layer ratio for
the three layers is about 20:60:20.
[00134] In this example, the core layer (or 'B' layer of the A:B:A
structure)
is un-pigmented, but in contrast with Film 'A,' the skin layers contain about
20 percent calcium
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carbonate (CaCO3) masterbatch, a voiding agent. As in the case of Film `A',
the ribs 503 of
Film '13' average about 6.5 mils tall, with an average spacing between ribs
503 of about 0.336
inches, The thickness of the web 505 between the ribs 503 was targeted to be
about 0.50 mils
thick. The example of Fig. 4a indicates that, absent any ring rolling, the
ribs 503 of Film 'B' have
a hazy translucent appearance due to the presence of the CaCO3 and the
thickness of the ribs 503,
while the web 505 between the ribs 503 was hazy but nearly colorless.
[00135] Figure
5b indicates the effect on Film 'B' of the peiformance of an MD ring
rolling process. In particular, Figures 5b-1 and 5b-2 illustrate the effect on
Film 'B' after
application of an MD ring rolling process using a 200 pitch tool and a DOE of
about 150 mils.
As shown in those Figures, MD ring rolling and consequent stretching of Film
'B' under these
parameters resulted in a relatively hazier appearance of the web 505 between
the ribs 503, while
the ribs 503 took on a visibly enhanced white color. Figures 5b-1 and 5b-2
further show that the
ribs 503 each comprise a white "stitch" 507 or cross pattern that
intermittently crosses each rib
503. This is particularly apparent when referring to the right hand side of
Figure 5b, where Film
13' is disposed on a black background. The "stitch" patterns are areas in
which the MD rollers
stress that particular area of the rib 503, causing the voiding agent, which
is stress-sensitive, to
react and produce areas of enhanced whiteness along the ribs 503. As in the
case of Film 'A' in
Figures 4a-1 through 4d-2, however, the stretching resulting from the TD ring
rolling process has
no such effect on the MD ring rolled Film 'B.' As discussed in more detail
below, the
aforementioned stitches are one example of indicia that may be produced in
connection with
various embodiments.
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[00136] Notably, Figures 5c-1 and 5c-2 illustrate Film 'B' after the
application, to the film
of Figures 5b- I and 5b-2, of a TD process using a 40 pitch tool and a DOE of
about 20 mils. As
indicated, that TD process produced no significant change in the ribs 503, or
in web 505.
[00137] F.3 Example Film 'C'
[00138] Figures 6a-1 through 6c-2 provide details concerning another
example ribbed
film, referred to herein as Film 'C.' In this particular example, Film 'C' is
an extruded ribbed
film that comprises three layers of linear low-density polyethylene (LLDPE),
having a layer
structure of A:B:A, wherein the layer ratio for the three layers is about
20:60:20. As in the case
of Films 'A' and 'B,' discussed above in connection with Figures 4a-1 through
5c-2, the ribs 603
of Film 'C' average about 6.5 mils tall, with an average spacing between ribs
603 of about 0.336
inches. The thickness of the web 605 between the ribs 603 was targeted to be
about 0.50 mils
thick.
[00139] In contrast with Film 'B, however, Film 'C' comprises a black
coloring agent that
causes the ribs 603 to appear black. Specifically, Film 'C' comprises a core
layer (layer B of
layer structure A:B:A) that was un-pigmented, albeit with skin layers (layers
A of structure
A:B:A) that contained a dilute pigment, about 0.5 percent black masterbatch in
this example. By
way of explanation, Applicants have found that a dilute pigment having a
concentration in the
range of about 0.25 percent to about 3.0 percent may provide acceptable
results in this and/or
other embodiments. Applicants have also found that concentrations in a range
of about 0.25
percent to about 2.0 percent may be useful in some instances, and
concentrations in a range of
about 0.25 percent to about 1.0 may be particularly useful in some instances.
[00140] With particular reference to Figures 6a-1 and 6a-2, which disclose
an un-stretched
version of Film 'C,' the ribs 603 appear black due to their thickness and the
presence of the black
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masterbatch. Due to its relative thinness, the web 605 between the ribs 603
can appear to be
nearly colorless to slightly hazy.
[00141] Figures 6b-1 and 6b-2, however, show the effects of applying an MD
stretching
process, to the film of Figures 6a-1 and 6a-2, where the ribs 603 are colored,
but otherwise
comprise no voiding agents that might change or enhance color with stress. The
MD ring rolling
was performed using a 200 pitch tool and a DOE of about 150 mils.
Specifically, Figures 6b-1
and 6b-2 show that applying MD stretching under these parameters can produce
some
intermittent deformation 607 of the film at uniform points along the ribs 603,
and a
corresponding hazier appearance of the ribs 603, but otherwise produce no
color change to the
ribs 603. Similarly, the web 605 can become hazier as well, but otherwise
undergo no color
change. The additional application, to the film of Figures 6b-1 and 6b-2, of a
TD process using a
40 pitch tool and a DOE of about 20 mils produced no discernible change in the
ribs 603 or
intervening film 605, as indicated in Figures 6c-1 and 6c-2. As discussed in
more detail below,
the aforementioned intermittent deformation of the ribs 603 is another example
of indicia that
may be produced in connection with various embodiments.
[00142] F.4 Example Film 'H'
[00143] Figures 7a-1 through 7c-2 and the corresponding text provide
details concerning
an example ribbed film referred to herein as Film 'H.' As indicated in those
figures, Film 'H' is
a ribbed film. In this particular example, Film 'H' is an extruded film that
comprises three layers
of linear low-density polyethylene (LLDPE). In this example, Film 'H' has a
layer structure of
A:B:A. The layer ratio for the three layers is about 20:60:20.
[00144] In this example, the core layer comprised about 6 percent black
masterbatch, and
the skin layers contained about 20 percent CaCO3 masterbatch. The ribs 703 of
Film 'H'
CA 2903554 2019-03-13
averaged about 6.5 mils tall, with an average spacing between ribs 703 of
about 0.336 inches.
The thickness of the intervening film 705 between the ribs 703 was targeted to
be about 0.50
mils thick.
[00145] Observation of Film 'H' in Figures 7a-1 and 7a-2 reveals hazy, gray
colored ribs,
and black film between the ribs. The sample of Figures 7a-1 and 7a-2 was not
subjected to any
post-extrusion processing. In the sample of Figures 7a-1 and 7b-2, which
reflects application of
an MD stretching process with a 200 pitch tool at a DOE of about 150 mils, the
ribs 703 have a
white, stitched 707 appearance, and the black web 705 between the ribs 703
remains black. As
indicated in Figures 7c-1 and 7c-2, a TD stretching process, with a 40 pitch
tool at about 20 mils
DOE, performed subsequent to the MD stretching process resulted in no color
change to the ribs
703 or to the web 705 between the ribs 703, as compared with the film of
Figures 7b-1 and 7b-2.
[00146] G. Examples of Post-Extrusion Processes and Resulting Indicia
[00147] As will be apparent from the foregoing discussion and example films
and
structures, various processes may be employed to provide indicia that may
convey information to
a user concerning an end product in which the film and/or structure is
employed.
[00148] In connection with the processes disclosed herein, including those
set forth in the
discussion of Figure 3 above, various physical indicators may result from the
performance of
those processes and/or may be present in precursor films used in such
processes. Consistent with
the foregoing, and as set forth in the discussion of the structures below,
such indicia may include,
for example, elements such as colors, dyes, pigments, textures, ribs,
corrugations, stars, dots,
bars, stitches, discontinuous lines, and combinations of any of the foregoing.
Not only are such
indicia readily apparent to a user of, for example, an end product in which
the discontinuously
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laminated film structure is employed, but such indicia may be advantageous
insofar as they are
perceptible by one or more senses of a user.
[00149] The indicia may be formed at various different times during the
production
process. For example, the indicia may be formed by post-extrusion processing
of an extruded
multilayer film. As another example, the indicia may be formed as part of a
discontinuous
lamination process in which an extruded multilayer film is discontinuously
laminated to one or
more other layers. As a further example, indicia may be formed both during
post-extrusion
processing of an extruded multilayer film, and also during a discontinuous
lamination process in
which that same extruded multilayer film is discontinuously laminated to one
or more other
layers.
[00150] Various types of indicia may be present in a particular end
product,
discontinuously laminated film structure, or precursor film. For example, one
type of indicia
may convey to a user information concerning an attribute of an end product.
Another type of
indicia may serve a largely cosmetic or aesthetic purpose. The foregoing
and/or other types of
indicia may be combined, for example, in a single end product.
[00151] By way of illustration, indicia may indicate visually, and/or in a
tactile sense,
certain attributes of the end product such as, for example, a relative
strength of the product.
Thus, the extruded ribs present in a precursor film enhance the strength of
the precursor film. As
well, such extruded ribs also provide a visible and tactile indicator, to a
user, of the strength of
the film and/or the strength of a discontinuously laminated film structure or
end product in which
that film is employed.
[00152] As another example, the stars or dots present in some of the
'Structures' noted
below serve as an indicator of highly localized stress whitening, such as may
be obtained with
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various combinations of ring rolling processes, such as MD and/or TD ring
rolling. The highly
localized stress whitening, which may result from ring rolling in a direction
generally orthogonal
to a direction of extruded ribs of a film, can serve as an indicator to a
consumer as to the strength
of the discontinuously laminated film structure, since the localized stress
whitening occurs at
points where the extruded ribs are worked by the teeth of a roller.
[00153] Moreover, the formation of indicia such as localized stress
whitening can be
localized and controlled using various combinations of voiding agents, and
coloring agents such
as dyes, dilute pigments, various processes such as cold MD and/or TD ring
rolling. Indeed,
such whitening can be highly localized, if desired, as evidenced by indicia
such as the dots and
stars disclosed elsewhere herein. More generally, stress-sensitive coloring
agents such as certain
dyes and pigments, and stress-sensitive voiding agents can be employed in one
or more layers of
a discontinuously laminated film structure such that formation of the layers
and/or the
discontinuously laminated film structure causes a change to the element(s)
that include the
coloring agent, thereby providing a visible manifestation of induced stress
and/or strain.
[00154] As noted above, some indicia within the scope of this disclosure
may be largely
cosmetic or aesthetic in nature. For example, MD ring rolling of the extruded
ribs in a ribbed
precursor film provides an interesting visual effect that may have little to
do with the strength or
integrity of the precursor film or associated discontinuously laminated film
structure.
[00155] Finally, and with regard to the foregoing discussion, it will be
apparent that
insofar as indicia convey to a user information concerning a property of a
precursor film,
discontinuously laminated film structure, and/or end product, such indicia are
example
implementations of means for conveying information perceptible by one or more
senses of a
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user. Thus, the indicia disclosed herein are provided solely by way of
example, and any other
indicia of comparable functionality may alternatively be employed.
[00156] In light of the disclosure herein, it will be appreciated that
embodiments of the
invention may be advantageous in various ways relative to conventional
structures and
processes. Below are set forth various examples of some advantages that may be
achieved in
connection with one or more embodiments of the invention. It is not necessary
that all of such
examples be present in any particular embodiment, nor is it necessary that any
particular
example be present in an embodiment. Finally, it should be noted that the
examples set forth
below are provided solely by way of illustration and are not intended, nor
should be construed, to
limit the scope of the invention in any way.
[00157] H. Example Advantages of Some Embodiments
[00158] With regard now to some possible advantages of example embodiments,
one or
more embodiments of the invention may substantially maintain their color
characteristics,
notwithstanding temporary or permanent deformation of the film. As another
example, one or
more embodiments of the invention may implement various visual effects, such
as coloration,
with non-metallic films. As a further example, one or more embodiments of the
invention may
implement various visual effects such as coloration without the use of color-
generating laminates
or layers. As yet another example, one or more embodiments of the invention
may provide
visual effects such as coloration without requiring user manipulation, such as
by bending or
delamination for example, with regard to the finished film. Moreover, one or
more embodiments
of the invention may implement desired visual effects with discontinuously
laminated films, and
thus do not require intimate contact between film layers. As well, one or more
embodiments of
the invention may implement desired visual effects with film structures that
include at least one
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ribbed film. Further, one or more embodiments of the invention may realize a
relative increase
in strength as a result of MD rolling and/or TD rolling of a ribbed precursor
film or a laminated
film that includes such a rolled precursor film. Moreover, the relative
strength of the film and/or
of a product that employs the film may be visually indicated to a user by
indicia such as a color,
contrasting colors, and/or distribution of the color in the film or product.
As another example,
the incremental stretching processes disclosed herein, such as TD and MD ring
rolling for
example, may be advantageous over conventional continuous-stretch processes
that do not
produce indicia and the other effects noted herein. As a final example, one or
more of the
embodiments disclosed herein may be advantageous inasmuch as they possess, or
produce, as
applicable, indicia using a continuous process. More conventional processes,
such as stamping
or embossing, are not well suited to be implemented in a continuous fashion.
Rather, only
discrete portions of the film can be stamped or embossed.
[00159] The
present invention may be embodied in other specific forms without departing
from its spirit or essential characteristics. For
example, the illustrated and described
implementations involve non-continuous (i.e., discontinuous or partially
discontinuous
lamination) to provide the light bonds. In alternative implementations, the
lamination may be
continuous. For example, multi film layers could be co-extruded so that the
layers have a bond
strength that provides for delamination prior to film failure to provide
similar benefits to those
described above. Thus, the described embodiments are to be considered in all
respects only as
illustrative and not restrictive. All changes that come within the meaning and
range of
equivalency of the claims are to be embraced within their scope.
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