Note: Claims are shown in the official language in which they were submitted.
CLAIMS
1. A plastic film having:
a. a main part formed of a film having an average thickness preferably of at
least 0.254 mm thick across the width; and
b. at least one area, preferably a longitudinal strip, having a thickness that
is
preferably at least about 5% higher than the average thickness of the main
part.
2. A plastic film according to claim 1, wherein: the at least one longitudinal
strip is
located at a peripheral edge of the plastic film.
3. A plastic film according to claim 1 or 2, wherein both longitudinal
peripheral
edges of the film are oversized and have a thickness that is at least 5%
higher than
the average thickness of the rest of the film.
4. A plastic film according to any one of claims 1 to 3, wherein the width of
an
oversized longitudinal peripheral edge ranges from about 1% to about 10% of
the
film width, preferably ranges from about 2% to about 6%.
5. A plastic film according to any one of claims 1 to 4, having two
longitudinal
peripheral oversized edges.
6. A plastic film according to any one of claims 1 to 5, wherein the shape of
the
peripheral edge, is such that the thickness reaches its maximum at the outer
edge(s) of the smooth edges.
7. A plastic film according to any one of claims 1 to 6, wherein the at least
longitudinal peripheral oversized edge is made of the same material of the
sheet.
8. A plastic film according to any one of claims 1 to 7, wherein at least the
thickness
of one of the longitudinal strips is different from the other thickened
strips.
9. A plastic film according to any one of claims 1 to 7, wherein the film is
made
from a natural or synthetic polymer, and is preferably made of at least one of
the
followings: High density Polyethylene (HDPE), Medium Density Polyethylene
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(MDPE), linear low density Polyethylene (LLDPE), Low density polyethylene
(LDPE) and Polyethylene for Raised Temperature (PERT) as well as
thermoplastic elastomers (TPEs) or thermoplastic olefins (TPOs), or any
combination thereof.
10. A plastic film of any one of claims 1-8 wherein the plastic film is filled
with any
kind of fillers, micro-fillers or nano-fillers such as, but not limited to,
short or
long glass fibers, talk, fire retardants, Carbon black or conductive
additives.
11. A plastic film of any one of claims 1-9, where the thickened areas are
only in
specific parts of the film, preferably on peripheral edges, more preferably in
a
discontinued way.
12. A plastic film of any one of claims 1 to 11, wherein the film is smooth at
either or
both sides of the film.
13. A plastic film of any one of claims 1 to 11, wherein the film is textured
on one
side or both sides of the film.
14. A plastic film of any one of claims 1 to 11, wherein the film is at least
partly
textured on at least one side of the film.
15. A plastic film of any one of claims 1 to 14, wherein the film is at least
partially
colored on at least one side of the film.
16. A plastic film of any one of claims 1 to 15, wherein the film is at least
partially
conductive on at least one side including or not the peripheral edges.
17. A plastic film, according to claims anyone of claims 1-16, wherein: the
longitudinal strip is located anywhere in the width of the plastic film and/or
in
continuous or discontinuous manner.
18. A plastic film, according to anyone of the claims 1-17, wherein: the
plastic film is
a geomembrane liner, wherein the liner is used for waste containment,
contaminated soil containment, fluid containment, mining containment, capping,
secondary containment, dam, canal, fluid control.
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19. A plastic film, according to anyone of the claims 1-18, wherein: the
plastic film is
composed of n layers where n.gtoreq.2.
20. A plastic film, according to claim 19, wherein at least one layer is not
conductive
or partially conductive.
21. A plastic film, according to claim 19, wherein at least 2 layers are
coextruded.
22. A plastic film, according to claim 19, wherein at least 2 layers are
laminated on
each other.
23. A plastic film, according to claim 19, wherein at least one layer is of a
different
thickness profile than the other layer(s).
24. A plastic film, according to claim 19, wherein at least one layer is made
of a
synthetic or natural polymer.
25. A plastic film, according to claim 24, wherein at least one layer is made
of
flexible non-polymeric material such as metallic films e.g. Aluminium or
copper.
26. A plastic film, according to claim 25, wherein the film is a multilayer
sandwich
panel of one or more plastic layers and one or more metal layers like
Aluminium
to be used in construction applications, or laminated packaging film of
similar
structure in food packaging applications.
27. A roller made of a plastic film, according to any one of claims 1 to 26,
rolled on a
spool.
28. A device for cooling a molten plastic film and form a thickened part of
the plastic
film, the device comprising: at least one solid element with controlled
temperature adapted to be installed at a die exit of a polymer processing
extruder
and having a surface configured to be in contact with a surface of said molten
plastic film, the device allowing controlled cooling of at least one surface
of the
molten plastic, wherein said cooling is performed through conduction heat
exchange between the surface of said solid element and the surface of said
molten
polymer film.
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29. A device, according to claim 28, wherein the temperature of at least one
part of
the surface of the element in contact with the film is controlled in a way
that the
said heat exchange between said molten polymer surface and said surface of the
solid element generates a thickening effect on at least one longitudinal
strip.
30. A device, according to claims 28 and 29, wherein the surface of the solid
element
has a dimension of about a dimension of the thickened part of the molten
plastic
film to be obtained.
31. The device of any one of claims 28 to 30, wherein the solid element is a
straight
plate, preferably of the same size of longitudinal strip of a desired size or
the
whole perimeter of the film.
32. The device of any one of claim 28 to 30, wherein the solid element is a
curved
plate of a desired size.
33. The device of any one of claim 28 to 32, where there solid element is made
of n
sections, wherein each of the n sections are similar or different and
connected or
separated, the difference may be in surface temperature, in the size or in the
form
of the solid object to cover a strip or the whole perimeter of the film.
34. The device of any one of claim 29-33, wherein the device is static i.e.
not
moving, or is moving or vibrating in any direction such as, but not limited
to,
rotating as in a calendar, moving up and down the machine direction
(vertically)
or moving in transverse direction (horizontally), in a continued or a
discontinued
manner.
35. The device of any one of claims 29 to 34, wherein the temperature of the
solid
object is controlled by a fluid or a gas flowing in the other side or inside
the solid
object to cool down the interface with the film.
36. The device of any one of claims 29 to 35, wherein the film has a thickness
of .ltoreq.
0.254 mm for different applications such as, but not limited to, food
packaging,
shopping bags, silage films, mulch film or shrink films.
37. The device of any one of claims 29 to 35, wherein the film has a thickness
.gtoreqØ254
mm and preferably ranging from about 0.254 mm to 3 mm, and especially
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ranging from 0.5 mm to 2.5 mm used for various applications such as, but not
limited to, geomembranes, caps and covers.
38. A method of adjusting the thickness of plastic film using the device of
any one of
claims 29 to 35, wherein the molten polymer, being pushed out of the die of a
blown film process, comes in contact with the cooling surface of the said
solid
element, wherein the solid element is installed after the die exit and before
the
solidification of the molten plastic film and the temperature is adjusted in a
way
that it results in the desired thickness which is preferably at least 5%
higher in
thickness than the average thickness of the film.
39. A method of claim 38, wherein both longitudinal peripheral edge being
oversized
and having a thickness that is at least 5% higher than the average thickness
of the
rest of the sheet.
40. A method of claim 38, wherein the width of an oversized longitudinal
peripheral
edge ranges from about 1% to about 10% of the film width, preferably ranges
from about 2% to about 6%.
41. A method of claim 38, wherein the film has two longitudinal peripheral
oversized
edges.
42. A method of claim 38, wherein the shape of the peripheral edge, after
cooling
with the method mentioned in this invention, is such that the thickness
reaches its
maximum at about the outer edge of the smooth edges.
43. A method of claim 38, wherein the thickened strip of the molten polymer
has
undergone a morphological transformation resulting in different molecular
structure such as different crystallinity and/or molecular orientation and/or
density.
44. A method of claim 38, wherein the device is installed all around the
perimeter of
the film to affect the whole width of the final film.
45. A method of anyone of claims 38 to 44, wherein the film is made from a
natural
or synthetic polymer, and is preferably made of at least one of the
followings:
High density Polyethylene (HDPE), Medium Density Polyethylene (MDPE),
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linear low density Polyethylene (LLDPE), Low density polyethylene (LDPE) and
Polyethylene for Raised Temperature (PERT) as well as thermoplastic elastomers
(TPEs) or thermoplastic olefins (TPOs), or any combination thereof.
46. A method of anyone of claims 38 to 44, wherein the thickened areas are
only in
certain spots of the film or peripheral edges in a discontinued way.
47. A method of anyone of claims 38 to 44, wherein the edges are characterized
by a
thickness of at least 5% higher than the average thickness of the rest of the
film
and with at least one edge which does not contain any conductive media.
48. A method of anyone of claims 38 to 44, wherein the film is smooth at
either or
both sides.
49. A method of anyone of claims 38 to 44, wherein the film is textured on one
side
or both sides.
50. A method of anyone of claims 38 to 44, wherein the film is colored on one
or both
sides.
51. A method of anyone of claims 38 to 44, wherein the liner is conductive on
one
side or both sides including or excluding the peripheral edges.
52. Any use of the polymeric film as defined in anyone of claims 1 to 26 or a
polymeric film obtained by the device of any one of claims 28 to 37 or through
the method defined in anyone of claims 38 to 44, in applications such as
geomembrane liners, capping and covers, packaging films, shopping bags, shrink
films, silage films and similar.
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