U.S. patent application number 13/449632 was filed with the patent office on 2012-10-25 for disposable lid having polymer composite of polyolefin and mineral filler.
This patent application is currently assigned to PACTIV LLC. Invention is credited to Alan H. Forbes, Wen Pao WU.
Application Number | 20120267368 13/449632 |
Document ID | / |
Family ID | 46025947 |
Filed Date | 2012-10-25 |
United States Patent
Application |
20120267368 |
Kind Code |
A1 |
WU; Wen Pao ; et
al. |
October 25, 2012 |
DISPOSABLE LID HAVING POLYMER COMPOSITE OF POLYOLEFIN AND MINERAL
FILLER
Abstract
Disposable lid comprises a thermoformed sheet in the shape of a
lid for a hot beverage container. The sheet comprises a polymer
composite of a polyolefin and at least one mineral filler. The
sheet has a thickness less than about 0.035 inches and a heat
deflection temperature at least comparable to that of high impact
polystyrene.
Inventors: |
WU; Wen Pao; (Pittsford,
NY) ; Forbes; Alan H.; (Victor, NY) |
Assignee: |
PACTIV LLC
Lake Forest
IL
|
Family ID: |
46025947 |
Appl. No.: |
13/449632 |
Filed: |
April 18, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61477886 |
Apr 21, 2011 |
|
|
|
Current U.S.
Class: |
220/200 |
Current CPC
Class: |
B65D 43/00 20130101;
C08K 3/34 20130101; C08K 3/10 20130101; C08K 3/34 20130101; C08L
23/02 20130101; C08K 3/10 20130101; C08L 23/02 20130101 |
Class at
Publication: |
220/200 |
International
Class: |
B65D 51/00 20060101
B65D051/00 |
Claims
1. A disposable lid comprising: a thermoformed sheet in the shape
of a lid for a hot beverage container, the sheet comprising a
polymer composite of a polyolefin and at least one mineral filler;
wherein the sheet has a thickness less than about 0.035 inches and
a heat deflection temperature at least comparable to that of high
impact polystyrene.
2. The disposable lid of claim 1, wherein the heat deflection
temperature is at least about that of high impact polystyrene.
3. The disposable lid of claim 1, wherein the heat deflection
temperature according to ASTM D648-06 Standard Test Method for
Deflection Temperature of Plastics Under Flexural Load in the
Edgewise Position (2006) is at least about 87.degree. C.
4. The disposable lid of claim 1, wherein the mineral filler
includes a high aspect ratio mineral filler.
5. The disposable lid of claim 4, wherein the mineral filler is
selected from the group consisting of talc, mica, wollastonite, or
combinations thereof.
6. The disposable lid of claim 4, wherein the polymer composite
comprises at least about 10% by weight of the mineral filler.
7. The disposable lid of claim 1, wherein the mineral filler
includes a low aspect ratio mineral filler.
8. The disposable lid of claim 7, wherein the mineral filler
includes calcium carbonate.
9. The disposable lid of claim 7, wherein the polymer composite
comprises at least about 20% by weight of the mineral filler.
10. The disposable lid of claim 1, wherein the polyolefin is
selected from the group consisting of polypropylene homopolymer,
polypropylene impact copolymer, ethylene-propylene random
copolymer, high density polyethylene, or combinations thereof.
11. The disposable lid of claim 1, wherein the polyolefin includes
polypropylene, the mineral filler includes a high aspect ratio
mineral filler, and the polymer composite comprises at least about
10% by weight of the mineral filler.
12. The disposable lid of claim 1, wherein the polyolefin includes
polypropylene, the mineral filler includes a low aspect ratio
mineral filler, and the polymer composite comprises at least about
20% by weight of the mineral filler.
13. The disposable lid of claim 1, wherein the polyolefin includes
high density polyethylene, the mineral filler includes a high
aspect ratio mineral filler, and the polymer composite comprises at
least about 20% by weight of the mineral filler.
14. The disposable lid of claim 1, wherein the polyolefin includes
high density polyethylene, the mineral filler includes a low aspect
ratio mineral filler, and the polymer composite comprises at least
about 40% by weight of the mineral filler.
15. The disposable lid of claim 1, wherein the polyolefin includes
polypropylene, the mineral filler includes a high aspect ratio
mineral filler, and the polymer composite has a shrinkage
comparable to that of high impact polystyrene.
16. The disposable lid of claim 15, wherein the polymer composite
has a shrinkage of about 0.5% to about 1.0% when measured according
to the ASTM D955 standard (1996).
17. The disposable lid of claim 15, wherein the polymer composite
comprises about 20% to about 40% by weight of the mineral
filler
18. The disposable lid of claim 1, wherein the polyolefin includes
high density polyethylene, the mineral filler includes a high
aspect ratio mineral filler, and the polymer composite has a
shrinkage comparable to that of polypropylene.
19. The disposable lid of claim 18, wherein the polymer composite
has a shrinkage of about 1.25% to about 1.75% when measured
according to the ASTM D955 standard (1996).
20. The disposable lid of claim 18, wherein the polymer composite
comprises about 30% to about 50% by weight of the mineral
filler.
21. The disposable lid of claim 1, wherein the polymer composite
consists essentially of the polyolefin and the at least one mineral
filler.
22. The disposable lid of claim 1, wherein the polymer composite
further comprises additives selected from the group consisting of
colorants, processing aids, and combinations thereof.
23. The disposable lid of claim 1, wherein the hot beverage
container is a coffee cup.
24. The disposable lid of claim 1, wherein the polymer composite
has a carbon footprint lower than high impact polystyrene.
25. The disposable lid of claim 1, wherein the polymer composite
has a greenhouse gas emission lower than high impact polystyrene.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of and priority to U.S.
Provisional Application Ser. No. 61/477,886, filed Apr. 21, 2011,
which is hereby incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present application generally relates to polymer
compositions particularly suited for disposable lids and the like.
Particularly, the present application relates to a disposable lid
comprising a thermoformed sheet having a polymer composite of
polyolefin and at least one mineral filler.
[0004] 2. Description of Related Art
[0005] Hot beverages, such as freshly brewed coffee for people on
the go, are usually served in heavy paper cups with disposable
lids. Coffee is typically brewed at 90-96.degree. C., held at
82-88.degree. C. and served at 70-80.degree. C. A coffee cup lid
preferably has a mechanical strength to withstand the force
required to push the lid onto the cup and to maintain the
dimensional stability at the temperature of the coffee. The
mechanical strength of a material within a range of temperatures
can be correlated to the material's heat deflection temperature
("HDT") or deflection temperature under load ("DTUL"). Current
lidding material for hot beverage cups is primarily made of high
impact polystyrene ("HIPS"), which has an ease of processing and a
good balance between rigidity and toughness due to its amorphous
structure. However, high impact polystyrene resin can be
susceptible to chemical attack and solvent crazing. In addition,
the presence of residual styrene monomer in the resin can cause an
unpleasant odor. Furthermore, high impact polystyrene resin,
amongst all the commodity resins, has a comparatively high carbon
footprint. Therefore, there remains an opportunity for an improved
disposable lid.
SUMMARY OF THE INVENTION
[0006] The purpose and advantages of the present application will
be set forth in and apparent from the description that follows, as
well as will be learned by practice of the application. Additional
advantages of the application will be realized and attained by the
apparatus particularly pointed out in the written description and
claims hereof, as well as from the appended drawings.
[0007] To achieve these and other advantages and in accordance with
the purpose of the application, as embodied and broadly described,
the application includes a disposable lid comprising a thermoformed
sheet in the shape of a lid for a hot beverage container. The sheet
comprises a polymer composite of a polyolefin and at least one
mineral filler. The sheet has a thickness less than about 0.035
inches and a heat deflection temperature at least comparable to
that of high impact polystyrene.
[0008] In accordance with one aspect, the heat deflection
temperature can be at least about that of high impact polystyrene.
Particularly, the heat deflection temperature according to ASTM
D648-06 Standard Test Method for Deflection Temperature of Plastics
Under Flexural Load in the Edgewise Position (2006) can be at least
about 87.degree. C.
[0009] As embodied herein, the mineral filler can include a high
aspect ratio mineral filler, for example, selected from the group
consisting of talc, mica, wollastonite, or combinations thereof.
For example, the polymer composite can comprise at least about 10%
by weight of the high aspect ratio mineral filler. Additionally or
alternatively, the mineral filler can include a low aspect ratio
mineral filler, such as calcium carbonate. For example, the polymer
composite can comprise at least about 20% by weight of the low
aspect ratio mineral filler. The polyolefin can be selected from
the group consisting of polypropylene homopolymer, polypropylene
impact copolymer, ethylene-propylene random copolymer, high density
polyethylene, or combinations thereof.
[0010] In one embodiment, the polyolefin includes polypropylene,
the mineral filler includes a high aspect ratio mineral filler, and
the polymer composite comprises at least about 10% by weight of the
mineral filler. In another embodiment, the polyolefin includes
polypropylene, the mineral filler includes a low aspect ratio
mineral filler, and the polymer composite comprises at least about
20% by weight of the mineral filler. In yet another embodiment, the
polyolefin includes high density polyethylene, the mineral filler
includes a high aspect ratio mineral filler, and the polymer
composite comprises at least about 20% by weight of the mineral
filler. In yet another embodiment, the polyolefin includes high
density polyethylene, the mineral filler includes a low aspect
ratio mineral filler, and the polymer composite comprises at least
about 40% by weight of the mineral filler.
[0011] In accordance with another aspect, the polyolefin can
include polypropylene, the mineral filler can include a high aspect
ratio mineral filler, and the polymer composite can have a
shrinkage comparable to that of high impact polystyrene. For
example, the polymer composite can have a shrinkage of about 0.5%
to about 1.0% when measured according to the ASTM D955 standard
(1996). In this manner, the polymer composite comprises about 20%
to about 40% by weight of the mineral filler.
[0012] In accordance with another aspect, the polyolefin can
include polyethylene, the mineral filler can include a high aspect
ratio mineral filler, and the polymer composite can have a
shrinkage comparable to that of polypropylene. As such, the polymer
composite can have a shrinkage of about 1.25% to about 1.75% when
measured according to the ASTM D955 standard (1996). In this
embodiment, the polymer composite comprises about 30% to about 50%
by weight of the mineral filler.
[0013] In accordance with one aspect of the disclosed subject
matter, the polymer composite consists essentially of the
polyolefin and the at least one mineral filler. However, the
polymer composite can further comprise additives selected from the
group consisting of colorants, processing aids, and combinations
thereof.
[0014] As embodied herein, the hot beverage container can be a
coffee cup, although a lid for other suitable containers is
contemplated.
[0015] In accordance with another aspect, the polymer composite can
have a carbon footprint lower than high impact polystyrene. For
example, the polymer composite can have a greenhouse gas emission
lower than high impact polystyrene.
[0016] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and are intended to provide further explanation of the application
claimed.
[0017] The accompanying drawings, which are incorporated in and
constitute part of this specification, are included to illustrate
and provide a further understanding of the apparatus of the
application. Together with the written description, the drawings
serve to explain the principles of the application.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a graph of the heat deflection temperature of neat
high impact polystyrene, neat polypropylene, neat high density
polyethylene, and certain mineral filled polymer composites,
respectively, in accordance with the disclosed subject matter.
[0019] FIG. 2 is a graph of the shrinkage characteristics of neat
high impact polystyrene, neat polypropylene, neat high density
polyethylene, and certain mineral filled polymer composites,
respectively, in accordance with the disclosed subject matter.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0020] Reference will now be made in detail to the present
preferred embodiments of the application, examples of which are
illustrated in the accompanying drawings. The disposable lids
presented herein generally are intended for use with cups or other
containers for holding high temperature beverages, such as coffee.
Although reference will be made herein to lids for hot beverage
cups, other similar or suitable uses are contemplated.
[0021] Typically, polyolefins have a heat deflection temperature
lower than high impact polystyrene ("HIPS") and thus are not
suitable for use alone (i.e., neat) as a lidding material for hot
beverage cups. However, in accordance with the disclosed subject
matter, the heat deflection temperature of the polyolefin can be
improved by adding at least one mineral filler to form a polymer
composite. The resulting polymer composite can have a heat
deflection temperature at least about that of high impact
polystyrene and thus be suitable for use as a lidding material for
hot beverage cups or the like.
[0022] Disposable lids in accordance with the disclosed subject
matter include a thermoformed sheet in the shape of a lid for a hot
beverage container. The sheet comprises a polymer composite of a
polyolefin and at least one mineral filler. The sheet has a
thickness less than about 0.035 inches and a heat deflection
temperature at least comparable to that of high impact
polystyrene.
[0023] In one embodiment, the mineral filler can include any
suitable mineral filler for increasing the heat deflection
temperature of the polyolefin. For example but without limitation,
the mineral filler can include a high aspect ratio filler, a low
aspect ratio filler, or a blend of both. The term "aspect ratio" of
a particle is defined herein for purpose of understanding as a
ratio of a largest dimension of the particle divided by a smallest
dimension of the particle. The aspect ratios are determined by
scanning under an electron microscope (2,000 times magnified) and
visually viewing the outside surfaces of the particles to determine
the lengths and thicknesses of the particles.
[0024] A high aspect ratio filler is defined herein as a filler
having an aspect ratio of at least about 5:1. The high aspect ratio
fillers of the present disclosed subject matter generally have an
aspect of from about 5:1 to about 40:1, and preferably from about
10:1 to about 20:1. The high aspect filler can include talc, mica,
wollastonite, or combinations thereof. Commercially available talc
materials include, but are not limited to, JETFIL.RTM. 575,
available from Luzenac America of Englewood, Colo. Commercially
available mica materials include SUZOREX.RTM. 325-PP, available
from Zemex Industrial Minerals, Inc. Commercially available
wollastonite includes, but is not limited to, the NYGLOS.RTM.
series of wollastonite, available from NYCO Minerals Inc. of
Calgary, Alberta, Canada.
[0025] A low aspect ratio filler of the disclosed subject matter
generally has an aspect ratio of from 1:1 to about 3:1, preferably
from 1:1 to about 2:1. The low aspect ratio filler can include
calcium carbonate, barium sulfate, or the combination thereof.
Commercially available calcium carbonate includes, but is not
limited to, OMYACARB FT.RTM., available from OMYA Inc. of
Cincinnati, Ohio, or Supercoat.RTM., from Imerys Performance
Minerals Inc. of Alpharetta, Ga. One example of commercially
available barium sulfate is BARITE 2075.RTM., available from Polar
Minerals in Mentor, Ohio.
[0026] When the at least one filler comprises a blend of high and
low aspect ratio fillers, the filler mixture can include any
suitable weight percentage of the high and low aspect ratio
fillers. For example, the filler mixture can comprise at least 50
wt. % high aspect ratio filler. In one embodiment, the filler
mixture can be from about 50 to about 80 wt. % high aspect ratio
filler and from about 20 to about 50 wt. % low aspect ratio
filler.
[0027] In accordance with one aspect, the polyolefin can be any
suitable polyolefin. For example but without limitation, the
polyolefin can be selected from the group consisting of
polypropylene homopolymer, polypropylene impact copolymer,
ethylene-propylene random copolymer, high density polyethylene, or
combinations thereof. The polyolefin can be a blend of homopolymer
polypropylene and impact copolymer polypropylene, in any desired
weight percent, such as a 60/40 blend, or a blend ratio sufficient
o achieve a desirable impact property of the composite.
[0028] In accordance with one aspect, the polymer composite can
consist essentially of the polyolefin and the at least one mineral
filler. However, the polymer composite can further comprise any
additives known to one of ordinary skill in the art. For example,
but without limitation, the additive can include colorants,
processing aids such as those commonly used for processing
composites, or combination thereof.
[0029] In accordance with one aspect, the disposable lid can be
formed using a variety of conventional manufacturing and forming
processes, including thermoforming or injecting molding processes,
although a thermoforming process is employed herein. According to
one method of manufacturing, pellets of a polyolefin resin are
melted in a twin screw extruder. Powders of the at least one
mineral filler are mixed with and/or added into the polyolefin melt
to form a blend. The blend is extruded through a die to form an
extruded sheet. The extruded sheet is then thermoformed to a
desired shape of the disposable lid. Alternatively, a
mineral-filled compound of high filler content in pellet form can
be produced from a typical compounding process, and the pellets
further diluted to a desirable filler content in the sheet
extrusion process.
[0030] The thickness of the lid can be selected as desired, but is
typically less than about 0.15 inches, preferably less than about
0.035 inches. Preferably, the lid can be about 0.01 to about 0.025
inches thick. The lid can be the natural color of the
polyolefin/filler mixture, or a variety of colors or color
combinations. The height, weight, shape, and design of the lid can
be selected as desired to fit a suitable hot beverage container,
such as a coffee cup, as is well known in the art. For example, the
lid can weigh about 3 to about 4 grams. Exemplary lid designs
include, but are not limited to, those described and shown in U.S.
Pat. Nos. 7,819,271, 7,789,260, 7,691,302, D556,573, D544,793,
D541,651 D541,650, D541,153, D540,675, D540,674, D540,673,
D540,672, D540,166, D540,165, D539,646, D533,778, D635,855,
7,731,047, 7,513,382, 7,246,715, D540,167, D539,650, D539,649,
D536,249, D535,561, 7,159,732, 7,156,251, 7,134,566, 7,131,551,
D530,602, 7,063,224, D514,445, D514,444, 6,874,649, 6,732,875,
D489,260, D485,758, 6,679,397, 6,644,490, D478,006, D477,223,
D476,891, D476,566, 4,753,365, D287,919, 4,615,459, and 4,589,569,
the contents of each of which is incorporated herein by reference
in its entirety.
[0031] In accordance with one aspect of the disclosed subject
matter, the heat deflection temperature ("HDT") also known as the
deflection temperature under load ("DTUL") can be determined
according to ASTM D648-06, Standard Test method for Deflection
Temperature of Plastics Under Flexural Load in the Edgewise
Position (2006). For the purpose of illustration and not
limitation, Table 1 includes the heat deflection temperature
measured according to the ASTM D648-06 standard (2006) for neat
high impact polystyrene, neat polypropylene ("PP"), neat high
density polyethylene ("HDPE"), and various mineral filled polymer
composites in accordance with the disclosed subject matter. The
data provided in Table 1 is based on nominally 12.7 mm wide by 3.17
mm thick injection molded bars with a span of 101.6 mm. A load of
2.5N was applied to achieve a fiber stress of 0.455 MPa (66 PSI).
The temperature of the heat-transfer medium was ramped at
2.0.degree. C./min. The deflection was reset to zero at 30.degree.
C. to allow for any low temperature creep. The temperature at which
the sample deflected an additional 0.25 mm was considered the heat
deflection temperature. For the purpose of illustration and not
limitation, FIG. 1 provides a graphical representation of the heat
deflection temperature data provided in Table 1. Particularly, FIG.
1 shows the increase of heat deflection temperature as a function
of mineral filler content for four different combinations of
polypropylene or high density polyethylene with talc or calcium
carbonate, respectively, as compared with neat HIPS as a
control.
TABLE-US-00001 TABLE 1 DTUL and IM Mold Shrinkage of HIPS, PP, HDPE
and Mineral-filled composites Filler IM mold Matrix Filler (wt
DTUL.sup.6 shrinkage Example Polymer Type %) (.degree. C.) (%)
Comparative Example 1 HIPS.sup.1 None 0 87 0.74% Comparative
Example 2 HDPE.sup.2 None 0 69 2.60% Comparative Example 3 PP.sup.3
None 0 80 1.53% Comparative Example 4 PP.sup.4 None 0 79 1.46%
Comparative Example 5 PP.sup.5 None 0 100 1.23% Inventive Example
01 HDPE.sup.2 Talc 11 79 2.33% Inventive Example 02 HDPE.sup.2 Talc
20 90 2.02% Inventive Example 03 HDPE.sup.2 Talc 30 96 1.61%
Inventive Example 04 HDPE.sup.2 Talc 40 108 1.53% Inventive Example
05 HDPE.sup.2 Talc 50 115 1.29% Inventive Example 06 HDPE.sup.2
CaCO.sub.3 10 68 2.82% Inventive Example 07 HDPE.sup.2 CaCO.sub.3
20 72 2.38% Inventive Example 08 HDPE.sup.2 CaCO.sub.3 30 79 2.29%
Inventive Example 09 HDPE.sup.2 CaCO.sub.3 40 84 2.06% Inventive
Example 10 HDPE.sup.2 CaCO.sub.3 50 92 1.76% Inventive Example 11
HDPE.sup.2 CaCO.sub.3 60 100 Inventive Example 12 PP.sup.3 Talc 10
105 0.94% Inventive Example 13 PP.sup.3 Talc 20 115 0.83% Inventive
Example 14 PP.sup.3 Talc 30 123 0.69% Inventive Example 15 PP.sup.3
Talc 40 130 0.60% Inventive Example 16 PP.sup.3 CaCO.sub.3 10 84
1.37% Inventive Example 17 PP.sup.3 CaCO.sub.3 20 89 1.29%
Inventive Example 18 PP.sup.3 CaCO.sub.3 30 93 1.24% Inventive
Example 19 PP.sup.3 CaCO.sub.3 40 97 1.06% Inventive Example 20
PP.sup.3 CaCO.sub.3 50 101 0.94% .sup.1High Impact Polystyrene,
Total Petrochemicals 940E .sup.2High Density Polyethylene, Density
= 0.963 g/cc .sup.3PP Homopolymer PP/Impact Copolymer blend. Blend
ratio 60/40 .sup.4PP Impact Copolymer .sup.5PP Homopolymer
.sup.6DTUL--Deflection Temperature Under Load (66 psi) per ASTM
D648.
[0032] As can be seen in the data of Table 1 and FIG. 1, neat high
impact polystyrene, with a heat deflection temperature of
87.degree. C., falls in between the range of temperature where
coffee is brewed and served. The heat deflection temperature of
polypropylene copolymer or polypropylene homopolymer/copolymer
blend, at about 79-80.degree. C., is lower than that provided by
neat high impact polystyrene. The heat deflection temperature for
neat high density polyethylene, at about 69.degree. C., however, is
shown to be outside the range of temperature where a lid made from
neat high density polyethylene would perform satisfactorily.
[0033] Examples 1-20 in accordance with the disclosed subject
matter of Table 1 show the heat deflection temperatures of various
polyolefin and mineral filler combinations at different levels of
mineral filler. Of the different polyolefin and mineral filler
combinations, the calcium carbonate filled polyolefins have a
gradual increase in heat deflection temperature relative a
respective non-filled (i.e. neat) polyolefin as the mineral content
is increased. By contrast, the talc filled polyolefins have a much
higher increase in heat deflection temperature as the mineral
filler content is increased. Unexpectedly, the talc filled
polypropylene has a more significant increase in heat deflection
temperature, even with the talc content as low as about 10%.
[0034] As shown in the data of Table 1 and FIG. 1, a polymer
composite in accordance with the disclosed subject matter therefore
can be provided with a heat deflection temperature comparable to,
equal to, or greater than high impact polystyrene. For example, to
achieve equal or greater heat deflection temperature than high
impact polystyrene, if the mineral filler includes a high aspect
ratio mineral (e.g. talc), the polymer composite can comprise as
little as about 10% by weight of the mineral filler (see Example
12). Indeed, as shown in FIG. 1, when polypropylene is used, even
less than 10% by weight of talc is needed to achieve the same heat
deflection temperature as high impact polystyrene. By contrast, if
the mineral filler includes a low aspect mineral filler (e.g.
calcium carbonate), the polymer composite can comprise at least
about 20% by weight of the mineral filler (see Example 17) to
achieve the equal or greater heat deflection temperature than high
impact polystyrene.
[0035] As shown by Example 2, when the polyolefin includes high
density polyethylene, the mineral filler includes a high aspect
ratio mineral filler (e.g. talc), and the polymer composite
comprises at least about 20% by weight of the mineral filler, the
heat deflection temperature will be greater than that of high
impact polystyrene. As shown by Example 10, when the polyolefin
includes high density polyethylene, the mineral filler includes a
low aspect ratio mineral filler (e.g. calcium carbonate), and the
polymer composite comprises at least about 50% by weight of the
mineral filler, the heat deflection temperature will be greater
than that of high impact polystyrene. As shown by Example 12, when
the polyolefin includes polypropylene, the mineral filler includes
a high aspect ratio mineral filler (e.g. talc), and the polymer
composite comprises at least about 10% by weight of the mineral
filler, the heat deflection temperature will be greater than that
of high impact polystyrene. As shown by Example 17, when the
polyolefin includes polypropylene, the mineral filler includes a
low aspect ratio mineral filler (e.g. calcium carbonate), and the
polymer composite comprises at least about 20% by weight of the
mineral filler, the heat deflection temperature will be greater
than that of high impact polystyrene.
[0036] For the purpose of illustration and not limitation, Table 1
and FIG. 2 shows the shrinkage characteristics of polypropylene,
high density polyethylene, high impact polystyrene and mineral
filled polypropylene and mineral filled high density polyethylene.
The shrinkage can be measured in accordance with the ASTM D955
(1996) standard using injection molded bars of the dimensions 12.7
min.times.3.2 mm.times.127 mm in accordance with the standard and
as well known in the art. Mineral filled polypropylene can overcome
disadvantages of polypropylene (neat) in the mismatch in shrinkage
as compared to high impact polystyrene, therefore allowing the use
of existing high impact polystyrene tooling for making a part with
similar shrinkage of between about 0.5% and about 1.0%. For
example, as shown in FIG. 2, talc filled polypropylene at 20-40%
talc is suitable for replacing high impact polystyrene from
shrinkage perspective. Similarly, mineral filled high density
polyethylene can overcome the disadvantage of high density
polyethylene in the mismatch in shrinkage as compared to
polypropylene, therefore allowing the use of existing polypropylene
tooling for making a mineral filled high density polyethylene part
with similar shrinkage to polypropylene of about 1.25% to about
1.75%. For example, as shown in FIG. 2, talc filled high density
polyethylene at 30-50% talc is suitable for replacing neat
polypropylene from shrinkage perspective.
[0037] In accordance with another aspect, the polymer composite can
have a carbon footprint lower than high impact polystyrene. For
example, the polymer composite can have a greenhouse gas emission
lower than high impact polystyrene. For the purpose of illustration
and not limitation, Table 2 shows cradle-to-grave greenhouse gases
emissions of lids in accordance with the disclosed subject matter
as compared to lids of high impact polystyrene. The two lids have
similar rigidity and perform similarly as a hot beverage cup lid.
The comparative example was made from high impact polystyrene sheet
of about 0.0214 inches thick and weighed about 3.83 grams. The
example in accordance with the disclosed subject matter include 40%
talc-filled polypropylene and was made from a 0.0167 inches thick
sheet and weighed about 3.32 grams. A base unit of 10,000 pieces
was used to calculate the greenhouse gases emissions. Several
factors contributed to the much lower greenhouse gases emission of
the example in accordance with the disclosed subject matter. These
factors include polymer density, GHG emission of base polymers and
minerals, and the amount of minerals incorporated in the composite.
As can be seen in FIG. 2, the talc filled polypropylene lid has a
nearly 50% reduction in greenhouse gases emission as compared to a
similarly performing lid made of high impact polystyrene.
TABLE-US-00002 TABLE 2 Greenhouse Gases Emissions of a typical hot
cup lid Weight of unit polymer GHG GHG Part weight Parts weight per
unit (Kg CO.sub.2 (Kg CO.sub.2 (grams) per unit (Kg) (Kg) eq./Kg
matl.) eq.) HIPS lids 3.83 10,000 38.3 38.3 4.68 81.5 40%
Talc-filled 3.32 10,000 33.2 19.3 2.88 43.5 PP lids % Reduction 50%
47%
[0038] While the present application is described herein in terms
of certain preferred embodiments, those skilled in the art will
recognize that various modifications and improvements can be made
to the application without departing from the scope thereof. For
example, which the present application describes a disposable lid
for a hot beverage container such as a coffee cup, the polymer
composites in accordance with the application could be used in
applications other than lidding where the improved heat deflection
temperature of a mineral filled polymer is desired. Thus, it is
intended that the present application include modifications and
variations that are within the scope of the appended claims and
their equivalents. Moreover, although individual features of one
embodiment of the application are discussed herein or shown in the
drawings of one embodiment and not in other embodiments, it should
be apparent that individual features of one embodiment can be
combined with one or more features of another embodiment or
features from a plurality of embodiments.
[0039] In addition to the specific embodiments claimed below, the
application is also directed to other embodiments having any other
possible combination of the dependent features claimed below and
those disclosed above. As such, the particular features presented
in the dependent claims and disclosed above can be combined with
each other in other manners within the scope of the application
such that the application should be recognized as also specifically
directed to other embodiments having any other possible
combinations. Thus, the foregoing description of specific
embodiments of the application has been presented for purposes of
illustration and description. It is not intended to be exhaustive
or to limit the application to those embodiments disclosed.
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