U.S. patent application number 15/336249 was filed with the patent office on 2017-12-28 for formable polyester films.
The applicant listed for this patent is Toray Plastics (America), Inc.. Invention is credited to Paige Manuel, Jan Moritz, Stefanos L. Sakellarides.
Application Number | 20170368807 15/336249 |
Document ID | / |
Family ID | 60675898 |
Filed Date | 2017-12-28 |
United States Patent
Application |
20170368807 |
Kind Code |
A1 |
Sakellarides; Stefanos L. ;
et al. |
December 28, 2017 |
FORMABLE POLYESTER FILMS
Abstract
A formable biaxially-oriented film includes a first layer. The
first layer includes from about 10 to about 90 wt. % crystalline
polyester and from about 10 to about 90 wt. % of a formability
enhancer to assist in increasing the polymeric chain flexibility.
The formability enhancer has a melting point less than about
230.degree. C. The film has a MD and a TD Young's Modulus of at
least 10% lower than a crystalline polyester film in the absence of
the formability enhancer. The film may further include a second
layer, which includes an amorphous copolyester. The second layer
may be adjacent to or attached to the first layer.
Inventors: |
Sakellarides; Stefanos L.;
(East Greenwich, RI) ; Manuel; Paige; (Newport,
RI) ; Moritz; Jan; (Bristol, RI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Toray Plastics (America), Inc. |
North Kingstown |
RI |
US |
|
|
Family ID: |
60675898 |
Appl. No.: |
15/336249 |
Filed: |
October 27, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62355695 |
Jun 28, 2016 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B32B 2307/704 20130101;
B32B 2439/46 20130101; B32B 27/22 20130101; B32B 2439/70 20130101;
B32B 2307/518 20130101; B32B 2307/7246 20130101; C08L 2203/16
20130101; A63H 2027/1025 20130101; B32B 2307/51 20130101; A63H
27/10 20130101; B32B 2270/00 20130101; B32B 2307/54 20130101; B32B
2307/738 20130101; C08L 2205/025 20130101; C08L 2207/04 20130101;
C08L 2205/06 20130101; B32B 2439/40 20130101; B32B 2255/10
20130101; C08K 5/12 20130101; B32B 27/36 20130101; B32B 2255/205
20130101; B32B 2307/702 20130101; B32B 2250/244 20130101; B32B
27/08 20130101; C08L 67/02 20130101 |
International
Class: |
B32B 27/22 20060101
B32B027/22; C08L 67/02 20060101 C08L067/02; C08K 5/12 20060101
C08K005/12; B32B 27/36 20060101 B32B027/36; B32B 27/08 20060101
B32B027/08 |
Claims
1. A formable biaxially-oriented film, the film comprising: a first
layer comprising from about 10 to about 90 wt. % crystalline
polyester and from about 10 to about 90 wt. % of a formability
enhancer to assist in increasing the polymeric chain flexibility,
the formability enhancer having a melting point less than about
230.degree. C., wherein the film has a MD and a TD Young's Modulus
of at least 10% lower than a crystalline polyester film in the
absence of the formability enhancer.
2. The formable film of claim 1, wherein the formability enhancer
is a homopolymer or copolymer comprising repeating units of
trimethylene terephthalate.
3. The formable film of claim 1, wherein the formability enhancer
is a homopolymer or copolymer comprising repeating units of
butylene terephthalate.
4. The formable film of claim 1, wherein the formability enhancer
is a copolyester elastomer.
5. The formable film of claim 1, wherein the formability enhancer
is a polyester comprising repeating units of at least one aliphatic
dicarboxylic acid or a polyester having more than four methylene
groups from aliphatic diols within repeating units.
6. The formable film of claim 1, wherein the film has a MD and TD
Young's Modulus of at least 20% lower than a crystalline polyester
film in the absence of the formability enhancer.
7. The formable film of claim 6, wherein the film has a MD and a TD
Young's Modulus of at least 30% lower than a crystalline polyester
film in the absence of the formability enhancer.
8. The formable film of claim 7, wherein the film has a MD and a TD
Young's Modulus of at least 40% lower than a crystalline polyester
film in the absence of the formability enhancer.
9. The formable film of claim 8, wherein the film has a MD and a TD
Young's Modulus of at least 50% lower than a crystalline polyester
film in the absence of the formability enhancer.
10. The formable film of claim 1, wherein the crystalline polyester
includes homopolyesters or copolyesters of polyethylene
terephthalate, polyethylene naphthalate, polyethylene
terephthalate-co-isophthalate copolymer, polyethylene
terephthalate-co-naphthalate copolymer, polycyclohexylene
terephthalate, polyethylene-co-cyclohexylene terephthalate,
polyether-ester block copolymer, ethylene glycol or terephthalic
acid-based polyester homopolymers and copolymers, or combinations
thereof.
11. The formable film of claim 1, wherein the crystalline polyester
includes homopolyesters or copolyesters of polyethylene
terephthalate.
12. The formable film of claim 1, wherein the thickness of the film
is from about 2 .mu.m to about 350 .mu.m.
13. The formable film of claim 12, wherein the thickness of the
film is from about 3 .mu.m to about 50 .mu.m.
14. The formable film of claim 13, wherein the thickness of the
film is from about 10 .mu.m to about 25 .mu.m.
15. A formable biaxially-oriented film, the film comprising: a
first layer comprising from about 10 to about 90 wt. % crystalline
polyester and from about 10 to about 90 wt. % of a formability
enhancer to assist in increasing the polymeric chain flexibility,
the formability enhancer having a melting point less than about
230.degree. C.; and a second layer comprising an amorphous
copolyester, the second layer being adjacent to the first layer,
wherein the film has a MD and a TD Young's Modulus of at least 10%
lower than a crystalline polyester film in the absence of the
formability enhancer.
16. The formable film of claim 15, wherein the amorphous
copolyester includes isophthalate modified copolyesters, sebacic
acid modified copolyesters, diethyleneglycol modified copolyesters,
triethyleneglycol modified copolyesters, cyclohexanedimethanol
modified copolyesters, or combinations thereof.
17. The formable film of claim 15, further including a third layer,
the third layer comprising an amorphous copolyester, the first
layer being attached to and located between the second and third
layers.
18. The formable film of claim 15, further including a third layer,
the third layer being a metallic barrier layer, the first layer
being attached to and located between the second and third
layers.
19. The formable film of claim 18, wherein the metallic barrier
layer includes titanium, vanadium, chromium, manganese, iron,
cobalt, nickel, copper, zinc, aluminum, gold, palladium or
combinations thereof.
20. The formable film of claim 19, wherein the metallic barrier
layer includes aluminum.
21. The formable film of claim 15, wherein the formability enhancer
is a homopolymer or copolymer comprising repeating units of
trimethylene terephthalate.
22. The formable film of claim 15, wherein the formability enhancer
is a homopolymer or copolymer comprising repeating units of
butylene terephthalate.
23. The formable film of claim 15, wherein the film has a MD and a
TD Young's Modulus of at least 20% lower than a crystalline
polyester film in the absence of the formability enhancer.
24. The formable film of claim 23, wherein the film has a MD and a
TD Young's Modulus of at least 40% lower than a crystalline
polyester film in the absence of the formability enhancer.
25. A formable biaxially-oriented film, the film comprising: at
least one layer comprising from about 10 to about 90 wt. %
crystalline polyester and from about 10 to about 90 wt. % of a
formability enhancer to assist in increasing the polymeric chain
flexibility, the formability enhancer having a melting point less
than about 230.degree. C., wherein the film has a composite MD and
TD Young's Modulus of less than about 500 kg/mm.sup.2.
26. The formable film of claim 25, wherein the film has a composite
MD and TD Young's Modulus of less than about 475 kg/mm.sup.2.
27. The formable film of claim 26, wherein the film has a composite
MD and TD Young's Modulus of less than about 450 kg/mm.sup.2.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This invention claims priority to U.S. Provisional Patent
Application No. 62/355,695 filed Jun. 28, 2016, which is hereby
incorporated by reference herein in its entirety.
FIELD OF INVENTION
[0002] The present invention relates generally to formable
biaxially-oriented films. More specifically, the present invention
is directed to biaxially-oriented films that include crystalline
polyester (e.g., crystalline polyethylene terephthalate (PET)) and
has a lower resistance to stretching and a softer feel.
BACKGROUND OF INVENTION
[0003] Films have been used in fresh meat products packaged at the
source (i.e., the meat-processing plant instead of the grocery
store). These products include, but are not limited to, pork or
beef tenderloins, imported racks of lamb, processed meats (e.g.,
ham, smoked turkey parts, and sliced processed meats ("cold
cuts")), cheese, and sausage products. Many of these products are
packaged in thermoformed fill-seal equipment that requires good
draw properties for the forming web. These type of films need to
have a higher degree of formability, while in certain applications
also need to have a high moisture barrier (low water vapor
permeability).
[0004] Decorated balloons formed from film laminates comprising a
polyester film layer (commonly referred to as "Mylar balloons")
have been gaining increasing popularity versus conventional latex
balloons in view of their ability to be printed with vivid,
colorful images, and more versatile and attractive appearances. For
example, Mylar balloons can be formed, for example, into
Valentine's Day heart shapes, flower shapes, and animal shapes.
These shapes may also include printing (e.g., famous characters)
thereon.
[0005] However, one drawback that limits commercial acceptance of
Mylar balloons is they are not capable of being blown into
intricate shapes, such as comic-book characters or famous character
silhouettes. Rather, the Mylar balloons are limited to simpler
shapes such as spheres, circles, shapes, hearts, and stars.
[0006] Accordingly, a need exists in flexible packaging for
polyester films that have a higher degree of formability, while
exhibiting a high moisture barrier. There is also a need for
formable balloons that have a desirable performance (e.g., extended
floating time).
SUMMARY OF THE INVENTION
[0007] According to one embodiment, a formable biaxially-oriented
film comprises a first layer. The first layer comprises from about
10 to about 90 wt. % crystalline polyester and from about 10 to
about 90 wt. % of a formability enhancer to assist in increasing
the polymeric chain flexibility. The formability enhancer has a
melting point less than about 230.degree. C. The film has a MD and
a TD Young's Modulus of at least 10% lower than a crystalline
polyester film in the absence of the formability enhancer.
[0008] According to another embodiment, a formable
biaxially-oriented film comprises a first layer and a second layer.
The first layer comprises from about 10 to about 90 wt. %
crystalline polyester and from about 10 to about 90 wt. % of a
formability enhancer to assist in increasing the polymeric chain
flexibility. The formability enhancer has a melting point less than
about 230.degree. C. The second layer comprises an amorphous
copolyester. The second layer is adjacent to the first layer. The
film has a MD and a TD Young's Modulus of at least 10% lower than a
crystalline polyester film in the absence of the formability
enhancer.
[0009] According to a further embodiment, a formable
biaxially-oriented film includes at least one layer. The at least
one layer comprises from about 10 to about 90 wt. % crystalline
polyester and from about 10 to about 90 wt. % of a formability
enhancer to assist in increasing the polymeric chain flexibility.
The formability enhancer has a melting point less than about
230.degree. C. The film has a composite MD and TD Young's Modulus
of less than about 500 kg/mm.sup.2.
[0010] The above summary is not intended to represent each
embodiment or every aspect of the present invention. Additional
features and benefits of the present invention are apparent from
the detailed description and figures set forth below.
BRIEF DESCRIPTION OF THE DRAWING
[0011] Other advantages of the invention will become apparent upon
reading the following detailed description and upon reference to
the drawings in which:
[0012] FIG. 1 is a generally cross-sectional view of a film
according to one embodiment of the present invention.
[0013] FIG. 2 is a generally cross-sectional view of a film
according to another embodiment of the present invention.
[0014] FIG. 3 is a generally cross-sectional view of a film
according to a further embodiment of the present invention.
[0015] FIG. 4 is a generally cross-sectional view of a film
according to yet another embodiment of the present invention.
[0016] FIG. 5 is a generally cross-sectional view of a film
according to a further embodiment of the present invention.
[0017] FIG. 6 is a generally cross-sectional view of a film
according to another embodiment of the present invention.
[0018] FIG. 7 is a generally cross-sectional view of a film
according to another embodiment of the present invention.
[0019] FIG. 8 is a generally cross-sectional view of a film
according to another embodiment of the present invention.
[0020] FIG. 9 is a generally cross-sectional view of a film
according to another embodiment of the present invention.
[0021] FIG. 10 is a generally cross-sectional view of a film
according to another embodiment of the present invention.
[0022] FIG. 11 is a generally cross-sectional view of a film
according to yet another embodiment of the present invention.
[0023] FIG. 12 is a plot showing Young Modulus (MD) versus
percentage of formability enhancers.
[0024] FIG. 13 is a plot showing Young Modulus (TD) versus
percentage of formability enhancers.
[0025] While the invention is susceptible to various modifications
and alternative forms, specific embodiments thereof have been shown
by way of example in the drawings and will herein be described in
detail. It should be understood, however, that it is not intended
to limit the invention to the particular forms disclosed, but on
the contrary, the intention is to cover all modifications,
equivalents, and alternatives falling within the spirit and scope
of the invention as defined by the appended claims.
DETAILED DESCRIPTION OF THE INVENTION
[0026] Referring to FIG. 1, a film 10 of the present invention
includes a first layer 12. The first layer 12 includes a
crystalline polyester and a formability enhancer to assist in
increasing the polymeric chain flexibility. The first layer
comprises from about 10 to about 90 wt. % crystalline polyester and
from about 10 to about 90 wt. % of the formability enhancer.
[0027] The crystalline polyester to be used in the first layer 12
includes homopolyesters or copolyesters of polyethylene
terephthalate (PET), polyethylene naphthalate (PEN), polyethylene
terephthalate-co-isophthalate copolymer, polyethylene
terephthalate-co-naphthalate copolymer, polycyclohexylene
terephthalate, polyethylene-co-cyclohexylene terephthalate,
polyether-ester block copolymer, ethylene glycol or terephthalic
acid-based polyester homopolymers and copolymers, or combinations
thereof. The polyester desirably used in the first layer includes
homopolyesters or copolyesters of polyethylene terephthalate
(PET).
[0028] Crystallinity is defined as the weight fraction of material
producing a crystalline exotherm when measured using a differential
scanning calorimeter (DSC). For a high crystalline PET, an
exothermic peak in the melt range of about 220 to about 290.degree.
C. is most often observed. High crystallinity is defined as the
ratio of the heat capacity of material melting in the range of
about 220 to about 290.degree. C. versus the total potential heat
capacity for the entire material present if it were all to melt. A
high crystalline polyester is a polyester that is capable of
developing a greater than 35% crystallinity during biaxial
orientation.
[0029] The crystalline polyester typically includes polyesters with
an intrinsic viscosity from about 0.50 to about 1.2 dL/g. The
crystalline PET resins typically have intrinsic viscosities from
about 0.60 to about 0.85 dL/g, a melting point of from about 255 to
about 260.degree. C., a heat of fusion of from about 30 to about 46
J/g, and a density of about 1.4 dL/g.
[0030] The formability enhancers used in forming the first layer 12
assist in providing a lower resistance to stretching and a softer
feel as compared to a film consisting only of crystalline
polyesters. It is desirable for the formability enhancers to
transfer their attributes to the first layer 12 to a degree that
equals or exceeds the weight average of the properties of the
starting polyesters.
[0031] Without being bound by theory, the formability enhancers
typically include a more flexible segment in their polymer backbone
as compared to a crystalline polyester such as crystalline PET.
This feature of increased chain flexibility may be characterized by
the number of methylene groups in the repeat units of the polymer
backbone (e.g., PET has 2 methylene groups; polytrimethylene
terephthalate (PPT) has 3 methylene groups; and polybutylene
terephthalate (PBT) has 4 methylene groups). Such increased
flexibility may also be characterized by generally having a lower
melting point than crystalline PET.
[0032] Non-limiting examples of materials that may be used as the
formability enhancer in the first layer 12 are: (1) Homopolymer or
copolymer polyesters of terephthalic acid with diols longer than
ethylene glycol (e.g., PTT (polytrimethylene terephthalate) or PBT
(polybutylene terephthalate)); (2) copolyester elastomers; (3)
polyesters comprising repeating units of at least one aliphatic
dicarboxylic acid (e.g., sebacic acid, azelaic acid, adipic acid or
combinations thereof); (4) polyesters having more than four
methylene groups from aliphatic diols within repeating units (e.g.,
hexanediol); or (5) combinations thereof.
[0033] The polytrimethylene terephthalate (PTT) resins generally
have intrinsic viscosities from about 0.9 to about 1.0 dL/g, a
melting point of from about 224 to about 227.degree. C., and heat
of fusion of from about 40 to about 70 J/g. Non-limiting commercial
examples of PTT resins include, but are not limited to,
Corterra.RTM. (Shell Chemicals Co.), Sorona.RTM. (DuPont.TM. Co.),
and Ecoriex.RTM. (SK Chemicals Co.).
[0034] The polybutylene terephthalate (PBT) resins generally have
intrinsic viscosities from about 1.0 to about 1.3 dL/g, a melting
point of about 223.degree. C., and a heat of fusion of from about
40 to about 70 J/g. Non-limiting commercial examples of PBT resins
include, but are not limited to, Crastin.RTM. grades (DuPont.TM.
Co.), Celanex.RTM. (Ticona.TM. division of Celanese Corp.), and
Toraycon.RTM. (Toray Industries, Inc.).
[0035] The copolyester elastomers generally have a melting point of
from about 150 to about 220.degree. C. Non-limiting commercial
examples of copolyester elastomeric resins include, but are not
limited to, Hytrel.RTM. grades (DuPont.TM. Co.) and Arnitel.RTM.
grades (DSM, Inc.).
[0036] Non-limiting example of polyesters comprising repeating
units of at least one aliphatic dicarboxylic acid or polyesters
having more than four methylene groups from aliphatic diols within
repeating units include, but are not limited to, the Vitel.RTM.
family of resins from Bostik, Inc. and Griltex.RTM. family of
resins from EMS-Griltech division of EMS-Chemie Holding AG.
[0037] The first layer 12 may include additives. Non-limiting
examples of desirable additives to be used in the first layer are
antiblock and slip additives. Antiblock and skip additives are
typically solid particles dispersed within a layer to effectively
produce a low coefficient of friction on the exposed surface. This
low coefficient of friction assists the film to move smoothly
through the film formation, stretching and wind-up operations. In
the absence of antiblock and slip additives, outer surfaces are
likely more tacky and increase the likelihood of the film being
fabricated to stick to itself or to the processing equipment, which
can cause excessive production waste and/or low productivity.
[0038] Examples of antiblock and slip additives that may be used
include, but are not limited to, amorphous silica particles with
mean particle size diameters in the range of from about 0.05 to
about 0.1 .mu.m at concentrations of from about 0.1 to about 0.4
mass-percent. For example, calcium carbonate particles or
precipitated alumina particles may be used as an antiblock and slip
additive. Calcium carbonate particles typically have a medium
particle size of from about 0.3 to about 1.2 .mu.m at
concentrations of about 0.03 to about 0.2 mass-percent.
Precipitated alumina particles of sub-micron sizes generally have
an average particle size of about 0.1 .mu.m and a mass-percent of
from about 0.1 to about 0.4.
[0039] Additional non-limiting examples of antiblock and slip
additives that may be used include inorganic particles, aluminum
oxide, magnesium oxide, titanium oxide, complex oxides (e.g.,
kaolin, talc, and montmorillonite), barium carbonate, sulfates
(e.g., calcium sulfate and barium sulfate), titanates (e.g., barium
titanate and potassium titanate), and phosphates (e.g., tribasic
calcium phosphate, dibasic calcium phosphate, and monobasic calcium
phosphate).
[0040] Blends of antiblock and slip additives may be used to
achieve a specific objective. For example, it is contemplated that
organic particles, vinyl materials (e.g., polystyrene, crosslinked
polystyrene, crosslinked styrene-acrylic polymers, crosslinked
acrylic polymers, and crosslinked styrene-methacrylic polymers),
crosslinked methacrylic polymers, benzoguanamine formaldehyde,
silicone, and polytetrafluoroethylene may be used as an antiblock
or slip additive.
[0041] The antiblock or slip additives may be included in the first
layer as a masterbatch addition in one embodiment. For example, the
first layer 12 may be formed by extruding a pellet-to-pellet mix
(i.e., dry blend) of crystalline polyester, the formability
enhancer, and a polyester masterbatch with the antiblock and slip
additives.
[0042] The first layer 12 may further include a conductive metal
compound. Non-limiting examples of conductive metal compounds that
may be added are calcium, manganese, magnesium, or combinations
thereof. The conductive metal compounds are typically from about 50
to about 100 ppm of the first layer 12. The conductive metal
compound may be added during the polymerization process as a
catalyst or additive, or in the process as a masterbatch to secure
sufficient conductivity for electric pinning in the film-making
process.
[0043] One non-limiting example of a calcium compound that may be
used is calcium acetate. Non-limiting examples of manganese
compounds that may be used include manganese chloride, manganese
bromide, manganese nitrate, manganese carbonate, manganese
acetylacetonate, manganese acetate tetrahydrate, and manganese
acetate dihydrate. Non-limiting examples of magnesium compounds
that may be used include magnesium chlorides and carboxylates.
Magnesium acetate is a particularly desirable compound.
[0044] Additional additives may be added to the first layer to
assist in suppressing coloring (yellowness) thereof. For example, a
phosphorous-based compound may be added to the first layer 12 to
assist in suppressing the coloring. Phosphorous-based compounds are
typically greater than about 30 ppm so as to sufficiently reduce
the undesirable coloring of the film. The phosphorous-based
compounds are typically less than about 100 ppm to assist in
avoiding haziness in the film.
[0045] Phosphorus-based compounds that may be used include, but are
not limited to, phosphoric acid-based compounds, phosphorous
acid-based compounds, phosphonic acid-based compounds, phosphinic
acid-based compounds, phosphine oxide-based compounds, phosphonous
acid-based compounds, and phosphonous acid-based compounds. In
addition to suppressing the color, it is desirable for the
phosphorus-based compound to have thermal stability and suppress
debris. Phosphoric acid-based and phosphonic acid-based compounds
are particularly desirable.
[0046] The first layer 12 generally has a thickness after biaxial
orientation of from about 3 to about 25 .mu.m. More specifically,
the thickness of the first layer 12 in one embodiment is from about
5 to about 20 .mu.m, or from about 8 to about 15 .mu.m.
[0047] Referring to FIG. 2, a film 50 includes the first layer 12
and a second layer 14. The first layer 12 includes a crystalline
polyester and a formability enhancer as discussed above. The second
layer 14 includes an amorphous copolyester. The amorphous
copolyester used in the second layer 14 may include isophthalate
modified copolyesters, sebacic acid modified copolyesters,
diethyleneglycol modified copolyesters, triethyleneglycol modified
copolyesters, cyclohexanedimethanol modified copolyesters, and
combinations thereof.
[0048] The second layer 14 is adjacent to the first layer 12 in the
film 50. More specifically, the second layer 14 is attached to the
first layer 12. If attached, the second layer may be co-extruded to
the first layer in forming the film. It is contemplated that the
second layer may be attached to the first layer by other
methods.
[0049] The second layer 14 generally has a thickness after biaxial
orientation of from about 0.1 to about 10 .mu.m. More specifically,
the thickness of the second layer 14 in one embodiment is from
about 0.2 to about 5 .mu.m, or from about 0.5 to about 2 .mu.m.
[0050] Referring to FIG. 3, a film 100 is shown that includes the
first layer 12, the second layer 14 and a third layer 16. The third
layer 16 may be formed of the same materials discussed above in
conjunction with the second layer 14. The first layer 12 is located
between the second layer 14 and the third layer 16. The first,
second and third layers may be co-extruded with each other to form
the film. It is also contemplated that additional layers may be
located between the first layer 12, the second layer 14 and the
third layer 16 in either symmetric or asymmetric structures.
[0051] The second layer 14 and the third layer 16 may also include
antiblock and slip additives. The antiblock and slip additive to be
used in the second layer 14 and the third layer 16 may be the same
as described above with respect to antiblock and slip additives
that may be used in the first layer 12. In this embodiment, it is
desirable for the antiblock and slip additives, if added, to be
included in the second layer 14 and/or the third layer 16.
[0052] The third layer 16 generally has a thickness after biaxial
orientation of from about 0.1 to about 10 .mu.m. More specifically,
the thickness of the third layer 16 in one embodiment is from about
0.2 to about 5 .mu.m, or from about 0.5 to about 2.0 .mu.m.
[0053] Referring to FIG. 4, a film 150 includes the first layer 12,
the second layer 14 and a third or barrier layer 18. The first
layer 12 is located between the second layer 14 and the third layer
18. The third layer 18 is a barrier layer that is typically a
metallic barrier layer.
[0054] The barrier layer 18 may include materials such as titanium,
vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc,
aluminum, gold, palladium, or combinations thereof for forming the
metallic barrier layer. One desirable material for the third layer
is aluminum.
[0055] It is contemplated that metal oxides may be used in forming
the barrier layer 18. One non-limiting example of a metal oxide
that may be used in the third layer is an aluminum oxide for
forming the metallic barrier layer. It is also contemplated that
other metallic materials may be used in forming the metallic
barrier layer. It also contemplated that silicone oxide may be used
in forming a barrier layer (third layer).
[0056] The barrier layer 18 generally has a thickness of from about
5 to about 100 nm. More specifically, the barrier layer 18 in one
embodiment is from about 20 to about 80 nm, and even more
specifically from about 30 to about 60 nm. The optical density of
the barrier layer 18 is generally from about 1.5 to about 5. More
specifically, the optical density of the barrier layer 18 in one
embodiment is from about 2 to about 4, and more desirably from
about 2.3 to about 3.2.
[0057] The barrier layer 18 assists in providing a gas and water
barrier in the film 150. It is desirable for the barrier layer 18
to have an oxygen transmission rate at 23.degree. C. and 0% RH of
from about 5 to about 50 cc/m.sup.2/day. It is desirable for the
barrier layer 18 to have an oxygen transmission rate at 23.degree.
C. and 0% RH of less than about 31 cc/m.sup.2/day. It is desirable
for the barrier layer to have a water vapor transmission at
38.degree. C. and 90% RH of from about 0.03 to about 0.70
g/m.sup.2/day and more desirably less than 0.31 g/m.sup.2/day.
[0058] In one process, the barrier layer 18 is deposited onto the
first layer 12 using vacuum deposition. It is contemplated that the
barrier layer 18 may be placed onto the first layer 12 by other
methods.
[0059] Before the barrier layer 18 is formed or placed onto the
first layer 12, the first layer 12 is desirably plasma treated to
clean and functionalize the outer surface thereof. The utilization
of the plasma treatment produces very high metal adhesion and it is
believed to increase the surface energy of the resultant metal
surface.
[0060] In addition to plasma-treatment processing, it is
contemplated that other surface treatment methods may be employed
in a vacuum system. For example, methods such as copper seeding,
nickel seeding or other sputtering treatment methodologies may be
used. The metal vapor may then be deposited on the outer surface of
the first layer 12 by high-speed, vapor-deposition metallizing
processes well known in the art to form the third layer 18.
[0061] In a further embodiment, a film 200 includes the first layer
12, the second layer 14, the third layer 16 and the barrier layer
18. The first layer 12 is located between the second layer 14 and
the third layer 16. The third layer 16 is located between the first
layer 12 and the barrier layer 18.
[0062] The films of the present invention may be coated or treated
on one or both sides of the film for adhesion promotion, surface
conductivity, higher wetting tension, or combinations thereof.
Preferred treatments include methods such as corona treatment,
plasma treatment, flame treatment, corona treatment in a controlled
atmosphere of gases, and in-line coating methods.
[0063] The films of the present invention are biaxially stretched
to obtain the desired crystallinity, thickness, gas barrier, and
mechanical properties. Biaxially stretching typically includes
stretching a polymer sheet along the machine direction (MD) on a
set of rolls rotating at progressively higher speeds and stretching
the sheet along the transverse direction (TD) by increasing the
film width using traveling clips in a stenter oven.
[0064] The MD and TD stretching of the film may be performed either
sequentially or simultaneously. For example, the MD and TD
stretching may be performed by: (1) first longitudinally (MD) and
then transversely (TD); (2) first transversely and then
longitudinally; (3) longitudinally, transversely, and again
longitudinally and/or transversely; or (4) simultaneously in both
the longitudinal and transverse directions. The biaxially
stretching is typically performed by longitudinally stretching and
then transversely stretching.
[0065] The films of the present invention have a lower resistance
to stretching and a softer feel as compared to standard polyester
films. The films of the present invention modify the stress-strain
curve manifested by reduction in modulus and yield strength. The
films of the present invention desirably combines the softness,
formability (manifested by reduced initial modulus and yield
strength) and puncture resistance of nylons with the high moisture
vapor and oxygen gas-barrier properties, and dimensional
stabilities of polyesters.
[0066] In one embodiment, the films of the present invention have a
MD Young's Modulus of at least 10% lower than a crystalline
polyester film in the absence of the formability enhancer. The
films of the present invention desirably have a MD Young's Modulus
of at least 20 or 30% lower than a crystalline polyester film in
the absence of the formability enhancer. The films of the present
invention desirably have a MD Young's Modulus of at least 40 or 50%
lower than a crystalline polyester film in the absence of the
formability enhancer.
[0067] In one embodiment, the films of the present invention have a
TD Young's Modulus of at least 10% lower than a crystalline
polyester film in the absence of the formability enhancer. The
films of the present invention desirably have a TD Young's Modulus
of at least 20 or 30% lower than a crystalline polyester film in
the absence of the formability enhancer. The films of the present
invention desirably have a TD Young's Modulus of at least 40 or 50%
lower than a crystalline polyester film in the absence of the
formability enhancer.
[0068] In a further embodiment, the films of the present invention
have both a MD and a TD Young's Modulus of at least 10% lower than
a crystalline polyester film in the absence of the formability
enhancer. The films of the present invention desirably have both a
MD and a TD Young's Modulus of at least 20 or 30% lower than a
crystalline polyester film in the absence of the formability
enhancer. The films of the present invention desirably have both a
MD and a TD Young's Modulus of at least 40 or 50% lower than a
crystalline polyester film in the absence of the formability
enhancer.
[0069] In another embodiment, the films of the present invention
have a composite MD and TD Young's Modulus of less than about 500
kg/mm.sup.2 as measured by ASTM D 882. The films of the present
invention desirably have a composite MD and TD Young's Modulus of
less than about 475 or about 450 kg/mm.sup.2 as measured by ASTM D
882. The films of the present invention more desirably have a
composite MD and TD Young's Modulus of less than about 400
kg/mm.sup.2 as measured by ASTM D 882.
[0070] In one embodiment, the first layer comprises from about 10
to about 90 wt. % crystalline polyester and from about 10 to about
90 wt. % of the formability enhancer. In another embodiment, the
first layer comprises from about 20 to about 80 wt. % crystalline
polyester and from about 20 to about 80 wt. % of the formability
enhancer. In a further embodiment, the first layer comprises from
about 30 to about 70 wt. % crystalline polyester and from about 30
to about 70 wt. % of the formability enhancer. In another
embodiment, the first layer comprises from about 40 to about 60 wt.
% crystalline polyester and from about 40 to about 60 wt. % of the
formability enhancer.
[0071] The films of the present invention may be used in
applications such as flexible packaging, in-mold and other labels,
and industrial uses. The films may also be used in balloon
applications. It is contemplated that the films of the present
invention may be used in other applications.
[0072] The films of the present invention typically are from about
2 to about 350 .mu.m in thickness after biaxial orientation. The
films are generally from about 3 to about 50 .mu.m and, more
specifically, from about 10 to about 25 .mu.m, and even more
specifically from about 12 to about 23 .mu.m in thickness after
biaxial orientation.
[0073] The thickness of film 100 in balloon applications is
generally from about from about 4 to about 12 .mu.m and, more
specifically, from about 5 to about 10 .mu.m after biaxial
orientation.
[0074] In one process, the films of the present invention are
formed by an extrusion process. The extrusion process includes
drying the masterbatch and crystallizable polyester (e.g., PET)
particles to desirably reach a moisture content of less than 100
ppm. The dried resins are fed to a melt processor such as a mixing
extruder. The molten material, including any additives, is extruded
through a slot die at about 285.degree. C., quenched and
electrostatically-pinned onto a chill roll (e.g., a chill roll
having a temperature about 20.degree. C.), in the form of a
substantively amorphous cast film. The cast film may then be
reheated and stretched.
[0075] The stretching temperatures are generally above the glass
transition temperature of the film polymer by about 10 to about
60.degree. C. Typical MD processing temperature is about 95.degree.
C. The longitudinal (MD) stretching ratio is generally from about 2
to about 6, and more desirably from about 3 to about 4.5. The
transverse stretching ratio is generally from about 2 to about 5,
and more desirably from about 3 to about 4.5. Typical TD processing
temperature is about 110.degree. C. If a second longitudinal or
transverse stretching is used, the ratios are generally from about
1.1 to about 5. Heat-setting of the film may follow at an oven
temperature of from about 180 to about 260.degree. C., desirably
from about 220 to about 250.degree. C. with a 5% relaxation to
produce a thermally dimensionally stable film with minimal
shrinkage. The film may then be cooled and wound up into roll
form.
[0076] Referring to FIG. 6, a film 250 includes the first layer 12,
the barrier layer 18 and a sealant layer 26. The first layer 12 is
located between the barrier layer 18 and the sealant layer 26. The
film 250 further includes printing 30 (e.g., a graphic design)
adjacent to the barrier layer 18. The printing may be performed
with a flexographic-printing press that prints a variety of colors.
After print application, the inks are typically dried in a roller
convective oven to remove solvents from the ink. One non-limiting
structure that may be formed from the film 250 is a balloon. It is
contemplated that the film 250 may be used in other
applications.
[0077] The sealant layer 26 assists in providing sealing to a
structure formed by the film. In one embodiment, the sealant layer
26 is a low-melt polyolefin layer. The polyolefin layer may be a
low density polyethylene (LLDPE), a low density polyethylene
(LDPE), or combinations thereof.
[0078] To facilitate bonding of the sealant layer 26 to the second
layer 14, an anchor layer or primer 34 may be used. This is shown,
for example, in a film 300 of FIG. 7. The film 300 includes the
first layer 12, the barrier layer 18, the sealant layer 26 and the
anchor layer 34.
[0079] One non-limiting example of an anchor layer 34 is a
water-based primer. Water-based primers enhance raw material
post-reclaiming by allowing the ability to wash away the primer in
an aqueous wash bath. This can assist in delamination of the other
layers from the sealant layer 26 and facilitate segregation into
separate polyester and polyethylene recycle streams. The sealant
layer 26 may be extrusion-coated to the anchor layer 34.
[0080] The anchor layer 34 may be selected from, but is not limited
to, a polyethylene dispersion. One non-limiting example of a
material that may form the anchor layer is polyethylenimine. The
anchor layer 34 may be applied in a water dispersion or another
solvent, using an application method such as gravure coating, Meyer
rod coating, slot die, knife-over-roll, or other variation of
solution coatings.
[0081] The applied dispersion may then be dried with hot air,
leaving the anchor layer 34 having a dried thickness of from about
0.01 to about 0.1 .mu.m. The first layer 12 may be treated prior to
applying the anchor layer 34. The treatment increases the surface
energy of the first layer 12 to increase wetting of the dispersion
and bond strength of the dried anchor layer 34. Some non-limiting
treatment methods include, but are not limited to, corona, gas
modified corona, atmospheric plasma, and flame treatment.
[0082] Referring to FIG. 8, a film 350 includes the first layer 12,
the second layer 14, the barrier layer 18 and the sealant layer 26.
The first layer 12 is located between the third layer 18 and the
second layer 14. The second layer 14 is located between the first
layer 12 and the sealant layer 26. The film 350 further includes
printing 30 (e.g., a graphic design) adjacent to the barrier layer
18.
[0083] Referring to FIG. 9, a film 400 includes the first layer 12,
the second layer 14, the barrier layer 18, the sealant layer 26 and
the anchor layer 34. The first layer 12 is located between the
barrier layer 18 and the second layer 14. The second layer 14 is
located between the first layer 12 and the anchor layer 34. The
anchor layer 34 assists in attaching the second layer 14 and the
sealant layer 26. The second layer 14 may be treated prior to
applying the anchor layer 34. The treatment increases the surface
energy of the second layer 14 to increase wetting of the dispersion
and bond strength of the dried anchor layer 34. Some non-limiting
treatment methods include, but are not limited to, corona, gas
modified corona, atmospheric plasma, and flame treatment. The film
400 further includes printing 30 (e.g., a graphic design) adjacent
to the barrier layer 18.
[0084] Referring to FIG. 10, a film 450 is shown that includes the
first layer 12, the second layer 14, the barrier layer 18, the
sealant layer 26 and a polymeric gas-barrier layer 40. The film 450
further includes printing 30 (e.g., a graphic design) adjacent to
the third layer 18. The film 450 is especially desirable for
forming a balloon. It is contemplated that the film 450 may be used
in other applications.
[0085] The polymeric gas-barrier layer 40 may be made of materials
such as, for example, ethylene-vinyl alcohol (EVOH), polyvinyl
alcohol (PVOH), polyvinyl amine, and combinations thereof. It is
contemplated that other materials may be used in forming the
polymeric gas-barrier layer.
[0086] In addition, a proper cross-linker may be added to reinforce
the polymeric gas-barrier layer. Non-limiting examples of
cross-linkers include melamine-based cross-linkers, epoxy-based
cross-linkers, glyoxal-based cross-linkers, aziridine-based
cross-linkers, epoxyamide compounds, titanate-based coupling
agents, (e.g., titanium chelate), oxazoline-based cross-linkers,
isocyanate-based cross-linkers, methylolurea or alkylolurea-based
cross-linkers, aldehyde-based cross-linkers, acrylamide-based
cross-linkers, and combinations thereof.
[0087] The polymeric gas-barrier layer may be applied in a
dispersion or solution in water or another solvent, using an
application method such as gravure coating, Meyer rod coating, slot
die, knife over roll, or any variation of solution coating known in
the art. The applied dispersion or solution may then be dried with
hot air. The coating-receiving surface may be treated prior to
applying the polymeric gas-barrier layer.
[0088] The combination of the barrier layer 18 (e.g., a metallic
barrier layer) and the polymeric gas barrier layer creates a very
high gas barrier property that can further improve the life time
(or float time) of a balloon. In addition to improving the
gas-barrier characteristics of the film, the polymeric gas-barrier
layer applied to the surface of the barrier layer 18 can also
prevent damage or removal of the barrier layer 18 during the severe
processes of balloon fabrication and during handling by the end
consumer. The polymeric gas-barrier layer 40 may be softer than the
barrier layer 18 and is able to maintain a good barrier as the
secondary barrier layer after possessing and handling.
[0089] It is contemplated that the polymeric gas-barrier layer may
be placed in a different location within the film than that
depicted in FIG. 10.
[0090] It is also contemplated that the film of FIG. 10 may further
include the anchor layer 34. This is shown, for example, in FIG. 11
with film 500. In this embodiment, the anchor layer 34 is located
between the second layer 14 and the sealant layer 26.
[0091] Once the laminations are prepared, the following process may
be used to fabricate the film into balloons: (1) flexographic
printing of graphic designs on the opposite surface of the sealant;
(2) slitting of the subsequent printed web; (3) fabrication of
balloons by die-cutting and heat sealing process; and (4) folding
and packaging of the finished balloons.
[0092] Flexographic printing is well known in the art and may be
used to print graphic designs on the balloons. The printing
equipment used in this process may be set up in a manner that will
prevent scratching, scuffing or abrading the gas-barrier surface.
The opposite side of the sealant layer of the laminate may be
printed on the metal surface with up to 10 colors of ink using a
flexographic printing press. Each color receives some drying prior
to application of the subsequent color. After printing, the inks
may be fully dried in a roller convective oven to remove all
solvents from the ink.
[0093] Slitting may be accomplished in any suitable fashion known
in the art. The slitting equipment used in this process is
desirably set up in a manner that will prevent scratching, scuffing
or abrading the gas barrier surface. In one embodiment, the printed
web may be cut to lengths adequate for the balloon-fabrication
process by rewinding on a center driven rewinder/slitter using
lay-on nip rolls to control air entrapment of the rewound roll.
[0094] The printed web may be cut to lengths adequate for a balloon
fabrication process by rewinding on a driven rewinder/slitter using
lay-on nip rolls to control air entrapment of the rewound roll.
[0095] Balloon fabrication may be accomplished in any suitable
fashion known in the art. The fabrication equipment used in this
process is desirably set up in a manner that will prevent or
inhibit scratching, scuffing or abrading the gas-barrier surface.
The slit webs may be fabricated into balloons by aligning two or
more webs into position so that the printed graphics are properly
registered to each other, then are thermally adhered to each other
and cut into shapes using known methods. A seam thickness of 1/64''
to 1/2'' may be used, as this seam thickness has been found to have
greater resistance to defects with an optimal seam being 1/16'' to
1/8''. Optionally, a valve can be inserted into an opening and the
layers abutting the valve adhered to form a complete structure.
[0096] Folding may be accomplished in any suitable fashion. The
folding equipment used in this process is desirably set up in a
manner that will prevent scratching, scuffing or abrading the gas
barrier surface. The fabricated balloons may be mechanically folded
along multiple axes using a mechanical process or by hand. The
balloon can be folded to the proper size and then loaded into a
pouch or box for downstream sales.
[0097] The balloons typically use gases that are lighter than area
including helium. It is contemplating that other gases may be
used.
[0098] The balloons generally have an oxygen transmission rate less
than about 150 cc/m.sup.2/day. The balloons typically have an
oxygen transmission rate less than about 50 or even less than about
30 cc/m.sup.2/day. The balloons typically have a floating time
greater than 20 days.
EXAMPLES
[0099] Examples 1-27 further define various aspects of the present
disclosure. These Examples are intended to be illustrative only and
are not intended to limit the scope of the present disclosure.
Also, parts and percentages are by weight unless otherwise
indicated. The inventive formulations of the films are shown in
Table 1 below and comprise blends of a polyester (crystalline
polyethylene terephthalate (PET)) and a formability enhancer.
[0100] The film preparations of Comparative Examples 1-5 and
Examples 1-26 were conducted on a pilot extrusion/biaxial
stretching film line utilizing a 20'' wide die and a final line
speed of about 100 feet/min. The film preparations described in
Comparative Example 6 and Example 27 were conducted on a commercial
extrusion/biaxial stretching film line utilizing a 75'' wide die
and a final line speed of about 800 and about 500 feet/min.,
respectively, for Comparative Example 6 and Example 27.
[0101] Resin materials for films used in the examples were as
follows:
[0102] PET resin ("PET-1"): film-grade crystalline PET resin F21MP
(IV=0.65 dL/g; Tm=255.degree. C.) manufactured by Toray Plastics
(America), Inc.
[0103] PET resin ("PET-2"): crystalline PET resin (IV=0.62 dL/g;
Tm=255.degree. C.) anti-block masterbatch type F18M, containing 2%
silica particles with an average size of 2 .mu.m (Fuji Silysia.RTM.
310P) manufactured by Toray Plastics (America), Inc.
[0104] PETG copolyester resin masterbatch ("PETG-m/b"): PETG
amorphous copolyester Eastar.TM. 6763 (made by Eastman Chemical
Co.) as the carrier resin. PETG-m/b is an antiblock masterbatch
based on 90 wt. % PETG resin 6763 and 10 wt. % of silica particles.
PETG 6763 is an amorphous copolyester of terephthalic acid with a
diol mixture consisting of about 33 mole % of 1,4-cyclohexane
dimethanol and about 67 mole % of ethylene glycol.
[0105] Essentially amorphous copolyester resin ("IPET"): F55M resin
(IV=0.69 dL/g; Tm=205.degree. C.) manufactured by Toray Plastics
(America), Inc. based on 19:81 molar (=weight in this case) parts
combination of isophthalic/terephthalic acid reacted with ethylene
glycol
[0106] Block copolyester elastomer resin: Hytrel.RTM. 7246 from
DuPont.TM. Co., comprised 72% hard segment and 28% soft segment,
characterized by a melting point of 218.degree. C. and a melt flow
rate of 12.5.
[0107] Polybutylene terephthalate resin ("PBT"): Crastin.RTM.
FG6130 (made by DuPont.TM. Co.), characterized by an IV of 1.0 dL/g
and a melting point of 223.degree. C.
[0108] Polytrimethyelene terephthalate resin ("PTT"): Ecoriex.RTM.
from SK Chemical Co., characterized by an IV of 0.99 dL/g and a
melting point of 227.degree. C.
[0109] Polyesters comprising aliphatic moieties originating from
long aliphatic diacids or diols: Griltex D 1939E GF from
EMS-Griltech characterized by a melting point of 150.degree. C.
("Griltex 1939").
Testing Methods
[0110] The various properties in the above examples were measured
by the following methods:
[0111] Intrinsic viscosities (IV) of the film and resin were tested
according to ASTM D 460. This test method is for the IV
determination of polyethylene terephthalate (PET) soluble at 0.50%
concentration in a 60/40 phenol/1,1,2,2-tetrachloroethane solution
by means of a glass capillary viscometer.
[0112] Melting point of polyester resin was measured using a TA
Instruments Differential Scanning calorimeter model 2920. A 0.007 g
resin sample was tested according to ASTM D3418-03. The preliminary
thermal cycle was not used, consistent with Note 6 of the ASTM
standard. The sample was then heated up to 280.degree. C.
temperature at a rate of 10.degree. C./min., then cooled back to
room temperature. Then, the heat flow and temperature data was
recorded. The melting point was reported as the temperature at the
endothermic peak located in the temperature range between about 150
and about 280.degree. C.
[0113] Film tensile properties (e.g., Young's Modulus) were
measured according to ASTM method D882, using a Tensilon.TM.
tensile tester (made by A&D Company, Ltd.), at a test speed of
20 cm/min. and initial jaw separation of 10 cm. The composite
modulus is the arithmetic mean of Young's Modulus along the machine
direction (MD) and the transverse direction (TD).
[0114] Metal optical density (OD) was measured using a
GretagMacbeth GmbH model D200-II measurement device. The
densitometer was zeroed by taking a measurement without a sample.
Then, the optical density of the metallized polyester film layer
was measured every 3'' across the web and the average was reported
as the metal OD. Optical density is defined as the amount of light
reflected from the test specimen under specific conditions. Optical
density was reported in terms of a logarithmic conversion. For
example, a density of 0.00 indicates that 100% of the light falling
on the sample is being reflected. A density of 1.00 indicates that
10% of the light is being reflected; 2.00 is equivalent to 1% of
the light being reflected, etc.
[0115] Wetting tension of the surfaces of interest was measured
substantially in accordance with ASTM D2578-67.
[0116] Oxygen barrier was measured on a MOCON Ox-Tran.RTM. L series
device utilizing ASTM D3985. Testing conditions used were
73.degree. F., 0% relative humidity, and 1 atm. In this
measurement, the gas-barrier surface of the web was hand-laminated
using a rubber roller to a 1-mil (about 25 .mu.m) thick LDPE blown
film tape with a pressure-sensitive adhesive. The lamination
protected the gas-barrier surface from handling damage, but made no
significant contribution to the oxygen-barrier properties.
[0117] Metal adhesion, dry-bonding strength was measured by
heat-sealing of a Dow Chemical Co. PRIMACOR.RTM. 3300 ethylene
acrylic acid (EAA) cast film to the metal surface on a Testing
Machines, Inc. Sentinel.RTM. model 12 ASL heat sealer in a room
that was air-conditioned as 73.+-.4.degree. F. and 50.+-.5% RH. On
the back side of the film, an adhesive tape (3M Corp. grade
Scotch.RTM. 610) was applied to keep the film from breaking during
the test. The heat seal conditions were 220.degree. F. temperature,
a 20 seconds dwell time, a 40 psi jaw pressure, and one heated and
one unheated jaw. Prior to peel testing, the sealed materials were
cut so that each web could be gripped in a separate jaw of the
tensile tester and a 1''.times.1'' section of sealed material can
be peeled. The peel was initiated by hand and then the two webs
were peeled apart on an Instron.RTM. tensile tester in a
180.degree. configuration toward the PRIMACOR.RTM. film. If the
metal separated from the substrate and remained attached to the
PRIMACOR.RTM. film, then the mean force of the peel was reported as
the metal bond strength.
[0118] Wet bonding strength of the metal layer was measured by the
same procedure as dry bonding strength, with the exception that a
cotton swab soaked with water was used to apply water to the
interface of the sealed area during peeling.
[0119] Sealing strength of the film or balloon structure was
measured as following. The seal layer was sealed to itself using a
Pack Rite.RTM. heat sealer with 15''.times.3/8'' jaw. The heat seal
conditions were 405.degree. F. temperature, 2 seconds dwell time,
90 psi jaw pressure, and one heated and one unheated jaw. Prior to
peeling, the sealed materials were cut so that each web could be
gripped in a separate jaw of the tensile tester and 1'.times.3/8''
section of sealed material could be peeled. The two webs were
pealed apart on an Instron.RTM. tensile tester in a 90.degree.
configuration known as a T-peel. The peel was initiated at a speed
of 2 in./min. until 0.5 lbs. of resistance was measured to preload
the sample. Then, the peel was continued at a speed of 6 in./min.
until the load dropped by 20%, which signaled failure. The maximum
recorded load prior to failure was reported as the seal
strength.
[0120] Floating time of the balloon was determined by inflating the
balloon with helium gas and measuring the number of days that the
balloon remains fully inflated. A balloon was filled from a helium
source using a pressure-regulated nozzle designed for "foil"
balloons, such as the Conwin Carbonic Co. Precision Plus.TM.
balloon inflation regulator and nozzle. The pressure was regulated
to 16 inches of water column. The balloon was filled with helium in
ambient conditions of about 20.degree. C. temperature and 1
atmosphere barometric pressure. The balloon was secured using
adhesive tape on the outside of the balloon below the balloon's
valve access hole to avoid creating any slow leaks of helium gas
through the valve. During the testing, the balloon was kept in a
stable environment close to the above-stated ambient
conditions.
[0121] Changes in temperature and barometric pressure were recorded
to interpret float time results since major fluctuations can
invalidate the test. The balloon was judged to be no longer fully
inflated when the appearance of the balloon changed such that: (1)
the wrinkles running through the heat seal seam area became deeper
and longer, extending into the front face of the balloon; and (2)
the cross-section of seam became a V-shape, as opposed to the
rounded shape that characterizes a fully inflated balloon. At this
time the balloon will still physically float, but will no longer
have an aesthetically-pleasing appearance. The number of days
between initial inflation and the loss of aesthetic appearance
described above was reported as the floating time of the
balloon.
Comparative Examples ("Comp.")
[0122] A 48 gauge (12 .mu.m) monolayer polyester film was prepared
by extruding a 97:3 blend of resins PET-1 and PET-2 (i.e., in the
absence of a formability enhancer). The extruded melt curtain was
cast on a cooling drum held at 70.degree. F. and subsequently
stretched longitudinally at 180.degree. F. at draw ratio 3.0, and
then transversely at 190.degree. F. at draw ratio 3.75 and heat-set
at 400.degree. F. at 3% relaxation.
[0123] The results of the Young's Modulus film properties are shown
in Table 1 below.
TABLE-US-00001 TABLE 1 5% Formability Form. IPET Y. Modulus Stretch
Temp Relax. Enhancer in Enhancer (Layer (kg/mm.sup.2) (.degree. F.)
Temp. Stretch Ratio Example Layer 12 (wt. %) 14) MD TD MD TD
(.degree. F.) MD TD Series 1 Comp. 1 none 0 no 496 548 180 190 400
3 3.75 1 Hytrel .RTM. 7246 5 no 467 447 180 190 400 3 3.75 2 Hytrel
.RTM. 7246 10 no 435 524 180 190 400 3 3.75 Series 2 Comp. 2 none 0
no 539 580 180 180 400 3 4 3 Hytrel .RTM. 7246 15 no 426 537 180
180 400 3 4 4 Hytrel .RTM. 7246 20 no 351 500 160 180 400 3 4 5
Hytrel .RTM. 7246 25 no 354 512 160 180 400 3 4 6 Hytrel .RTM. 7246
30 no 324 442 160 180 400 3 4 7 Hytrel .RTM. 7246 35 no 332 393 160
180 400 3 4 Series 3 Comp. 3 none 0 yes 512 583 180 180 400 3 4 8
Hytrel .RTM. 7246 25 yes 433 503 160 180 400 3 4 9 Hytrel .RTM.
7246 30 yes 403 515 160 180 400 3 4 10 Hytrel .RTM. 7246 35 yes 299
355 160 180 400 3 4 11 Hytrel .RTM. 7246 40 yes 314 403 160 180 375
2.8 4 12 Hytrel .RTM. 7246 40 yes 369 315 160 180 375 2.8 3.75 13
Hytrel .RTM. 7246 50 yes 285 447 160 180 400 2.5 3.75 Series 4
Comp. 4 none 0 no 475 597 170 180 400 3 4 15 PTT 10 no 419 564 175
180 400 3 4 16 PTT 25 no 410 518 175 180 400 3 4 17 PTT 35 no 405
420 170 180 340 3 4 18 PTT 50 no 281 382 160 170 330 3 4 19 PTT 99
no 230 230 120 110 330 2.25 3 Series 5 Comp. 5 none 0 no 473 640
180 180 420 3 4.5 20 PBT 10 no 493 580 180 180 420 3 4.5 21 PBT 25
no 393 551 175 180 400 3 4.5 22 PBT 50 no 322 497 155 180 400 3 4.5
23 PBT 75 no 258 350 150 180 350 3 4.5 24 PBT 99 no 234 267 120 140
300 3 4.5 Series 6 25 Griltex 1939 5 no 401 509 170 190 400 3 4 26
Griltex 1939 10 no 409 503 150 180 400 3 3.75 Series 7 Comp. 6 none
0 yes 517 520 255 230 450 4.8 3.9 27 PBT 25 yes 395 438 248 230 400
4.4 3.9
[0124] The composite modulus and its % reduction derivations based
on date of Table 1 are shown below in Table 1a.
TABLE-US-00002 TABLE 1A Composite % Reduction in Formability
Formability Presence Modulus Composite Enhancer in Enhancer of IPET
Stretch Ratio (MD + TD)/2 Modulus vs. Example Layer 12 (wt. %)
(Layer 14) MD TD Kg/mm.sup.2 Comp. Ex. Series 1 Comp. 1 none 0 no 3
3.75 522 0% 1 Hytrel 7246 5 no 3 3.75 457 12% 2 Hytrel 7246 10 no 3
3.75 480 8% Series 2 Comp. 2 none 0 no 3 4 560 0% 3 Hytrel 7246 15
no 3 4 482 14% 4 Hytrel 7246 20 no 3 4 426 24% 5 Hytrel 7246 25 no
3 4 433 23% 6 Hytrel 7246 30 no 3 4 383 32% 7 Hytrel 7246 35 no 3 4
363 35% Series 3 Comp. 3 none 0 yes 3 4 548 0% 8 Hytrel 7246 25 yes
3 4 468 15% 9 Hytrel 7246 30 yes 3 4 459 16% 10 Hytrel 7246 35 yes
3 4 327 40% 11 Hytrel 7246 40 yes 2.8 4 359 35% 12 Hytrel 7246 40
yes 2.8 3.75 342 38% 13 Hytrel 7246 50 yes 2.5 3.75 366 33% Series
4 Comp. 4 none 0 no 3 4 536 0% 15 PTT 10 no 3 4 492 8% 16 PTT 25 no
3 4 464 13% 17 PTT 35 no 3 4 413 23% 18 PTT 50 no 3 4 332 38% 19
PTT 99 no 2.25 3 230 57% Series 5 Comp. 5 none 0 no 3 4.5 557 0% 20
PBT 10 no 3 4.5 537 4% 21 PBT 25 no 3 4.5 472 15% 22 PBT 50 no 3
4.5 410 26% 23 PBT 75 no 3 4.5 304 45% Series 6 25 Griltex 1939 5
no 3 4 455 17% 26 Griltex 1939 10 no 3 3.75 456 17% Series 7 Comp.
6 none 0 yes 3 4.5 410 26% 27 PBT 25 yes 3 4.5 304 45%
Examples 1-2
[0125] Comparative Example 1 was repeated with the exception that
Hytrel 7246 resin was added as a blending modifier at 5 and 10 wt.
%, respectively, replacing in each case an equal portion of PET-1.
The Young's Modulus film properties are shown in Tables 1 and
1A.
Comparative Example 2
[0126] A 48 gauge (12 .mu.m) monolayer polyester film was prepared
by extruding a 97:3 blend of resins PET-1 and PET-2 (i.e., in the
absence of a formability enhancer). The extruded melt curtain was
cast on a cooling drum held at 70.degree. F. and subsequently
stretched longitudinally at 180.degree. F. at draw ratio 3.0, and
then transversely at 180.degree. F. at draw ratio 4.0 and heat-set
at 400.degree. F. at 5% relaxation. The Young's Modulus film
properties are shown in Tables 1 and 1A.
Examples 3-7
[0127] Comparative Example 1 was repeated with the exception that
Hytrel 7246 was added as blending modifier at 15, 25, 30, and 35
wt. %, respectively, replacing in each case an equal portion of
PET-1. In some cases, stretching temperatures had to be modified as
shown in Table 1 to maintain a stable process. The Young's Modulus
film properties are shown in Tables 1 and 1A.
Comparative Example 3
[0128] A 48 gauge (12 .mu.m) two-layer polyester film was prepared
by extruding a 97:3 blend of resins PET-1 and PET-2 through a main
extruder, and 100% resin "IPET" through a sub extruder (i.e., in
the absence of a formability enhancer). The extruded melt curtain
was cast on a cooling drum held at 70.degree. F. and subsequently
stretched longitudinally at 180.degree. F. at draw ratio 3.0, and
then transversely at 180.degree. F. at draw ratio 4.0 and heat-set
at 400.degree. F. at 5% relaxation. For these drawing conditions,
the extruder RPM settings were adjusted so that the total film
thickness was 12 .mu.m and the IPET layer thickness was 1.5 .mu.m.
The Young's Modulus film properties are shown in Tables 1 and
1A.
Examples 8-13
[0129] Comparative Example 3 was repeated with the exception that
Hytrel 7246 was added as a blending modifier at 25, 30, 35, and 40,
and 50 wt. %, respectively, replacing in each case an equal portion
of PET-1. In some cases, stretching and relaxation temperatures and
draw ratios had to be modified as shown in Table 1 to maintain a
stable film-manufacturing process. The Young's Modulus film
properties are shown in Tables 1 and 1A.
Comparative Example 4
[0130] A 48 gauge (12 .mu.m) monolayer polyester film was prepared
by extruding a 97:3 blend of resins PET-1 and PET-2 (i.e., in the
absence of a formability enhancer). The extruded melt curtain was
cast on a cooling drum held at 70.degree. F. and subsequently
stretched longitudinally (MD) at 170.degree. F. at draw ratio 3.0,
and then transversely (TD) at 180.degree. F. at draw ratio 4.0 and
heat-set at 400.degree. F. at 5% relaxation. The Young's Modulus
film properties are shown in Tables 1 and 1A.
Examples 15-19
[0131] Comparative Example 1 was repeated with the exception that
the PTT resin was added as a blending modifier at 10, 25, 35, 50
and 100 wt. %, respectively, replacing in each case an equal weight
portion of PET-1 except in Example 19. In Example 19, PTT replaced
the entire content of PET-1 (98% of the total) and also half of the
PET-2 content (1% of the total), whereas the other half of PET-2
was replaced by "PETG-m/b." (1% of the total)). In some cases,
stretching temperatures and draw ratios had to be modified as shown
in Table 1 to maintain a stable process. The Young's Modulus film
properties are shown in Tables 1 and 1A.
Comparative Example 5
[0132] A 48 gauge (12 .mu.m) monolayer polyester film was prepared
by extruding a 98:2 blend of resins PET-1 and PET-2 (i.e., in the
absence of a formability enhancer). The extruded melt curtain was
cast on a cooling drum held at 70.degree. F. and subsequently
stretched longitudinally (MD) at 180.degree. F. at draw ratio 3.0,
and then transversely (TD) at 180.degree. F. at draw ratio 4.5 and
heat-set at 400.degree. F. at 5% relaxation. The Young's Modulus
film properties are shown in Tables 1 and 1A.
Examples 20-24
[0133] Comparative Example 1 was repeated with the exception that
PBT was added as a blending modifier at 10, 25, 35, 50, 99 wt. %,
respectively, replacing in each case equal weight proportion of
PET-1 (except in the case of example 24: in that case, PBT replaced
the entire content of PET-1 (98% of the total) and also half of the
PET-2 content, (1% of the total), whereas the other half of PET-2
was replaced by "PETG-m/b." (1% of the total)). In some cases,
stretching temperatures and draw ratios had to be modified as shown
in Table 1 to maintain a stable process. The Young's Modulus film
properties are shown in Tables 1 and 1A.
Examples 25 and 26
[0134] Comparative Example 1 was repeated with the exception that
Griltex 1939 was added as a blending modifier at 5 and 10 wt. %,
respectively, replacing in each case an equal weight proportion of
PET-1. In Example 26, the TD stretch ratio was modified as shown in
Table 1 to maintain a stable process. The Young's Modulus film
properties are shown in Tables 1 and 1A.
Comparative Example 6
[0135] A 36 gauge (9 .mu.m) two-layer polyester film was prepared
by extruding a 95:5 blend of resins PET-1 and PET-2 (i.e., in the
absence of a formability enhancer) through a main extruder, and
100% IPET resin through the sub-extruder. The extruded melt curtain
was cast on a cooling drum held at 70.degree. F. and subsequently
stretched longitudinally at 255.degree. F. (maximum temperature
settings in the MD stretching section; actual range was
235-255.degree. F.) at draw ratio 4.8; then transversely at
230.degree. F. at draw ratio 4.1 and heat-set at 450.degree. F. at
6% relaxation. For these drawing conditions, the extruder RPM
settings were adjusted so that the total film thickness was 12
.mu.m and the IPET layer thickness was 1.5 .mu.m. The Young's
Modulus film properties are shown in Tables 1 and 1A.
Example 27
[0136] Comparative Example 6 was repeated with the exception that
PBT was added as a blending modifier at 25 wt. % replacing an equal
weight proportion of PET-1 Stretching temperatures and draw ratios
were slightly modified as shown in Table 1 to maintain a stable
process. The Young's Modulus film properties are shown in Tables 1
and 1A.
[0137] FIGS. 12 and 13 are graphs that show the effect of the
formability enhancer on the Young's Modulus data presented in Table
1.
Film Conversion
[0138] The films of Examples 3-7 and Comparative Example 2 were
then metallized with aluminum (metallic barrier layer 18) to a
first layer 12 (PET-1 and PET-2 blend discussed above) so as to
obtain an optical density of 2.8. Prior to metallization, a
plasma-treatment process was used in the metalizing chamber to
prepare the surface of the first layer 12 for the metal deposition.
The energy density of the treatment was approximately 1 kJ/m.sup.2
and nitrogen gas was used.
[0139] A second layer 14 (IPET) was attached to the first layer 12
on an opposite surface of the metallic layer 18. The surface of the
second layer was corona-treated and was coated with and a solution
to form an anchor layer 34 (solution of Mica.RTM. A-131-X from Mica
Corp.) using a gravure coater. The anchor layer 34 was dried in a
convective dryer. The dried anchor layer was then extrusion-coated
with a sealant layer 26 (LLDPE) using Dow Chemical Co. Dowlex.TM.
3010 at a 13.6 .mu.m thickness at a temperature of 600.degree. F.
The anchor layer 34 was located between the second layer 14 and the
sealant layer 26.
[0140] The properties of the converted films (webs) are summarized
in Table 2 below. This data indicated that the trend of increased
formability (manifested by reduced modulus) displayed by the
polyester film as the formability enhancer increased was preserved
in the converted webs. The data further showed the unexpected
result of an improved heat seal (of the extrusion-coated sealant
layer (LLDPE) on itself) resulting from the webs. While not being
bound by theory, this may be related to the improved formability
and reduced stiffness of the base film.
TABLE-US-00003 TABLE 2 Web Web Y. Modulus Y. Modulus (MD) (TD) O2
TR Heat Seal Example Description (kg/mm.sup.2) (kg/mm.sup.2)
(cc/100 in.sup.2/day) Force (kg) Extension (in) Comp. 2 0% Hytrel
.RTM. 217 283 0.20 3.74 0.92 3 15% Hytrel .RTM. 171 233 0.20 3.58
1.93 4 20% Hytrel .RTM. 153 221 0.23 4.32 4.33 5 25% Hytrel .RTM.
144 201 0.26 3.81 3.9 6 30% Hytrel .RTM. 171 212 0.25 4.28 3.95 7
35% Hytrel .RTM. 194 223 0.30 2.86 2.01
[0141] The above description is presented to enable a person
skilled in the art to make and use the invention, and is provided
in the context of a particular application and its requirements.
Various modifications to the preferred embodiments will be readily
apparent to those skilled in the art, and the generic principles
defined herein may be applied to other embodiments and applications
without departing from the spirit and scope of the invention. Thus,
this invention is not intended to be limited to the embodiments
shown, but is to be accorded the widest scope consistent with the
principles and features disclosed herein.
* * * * *