Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02413096 2002-11-28
FIELD OF THE tNVENTiON
This invention relates to thin walled polyethylene containers. The
containers are useful for packaging foods such as cottage cheese and ice
cream.
BACKGROUND OF THE INVENTION
Plastic food containers are ubiquitous items of commerce. Ideally,
these containers should have thin walls (preferably from about 0.35
millimeters to 1.30 millimeters thick) in order to reduce the amount of
plastic used to produce the container. However, the containers must also
have strength at high temperatures (for example, to permit a container to
be filled with ricotta cheese at temperatures over 80°C) and at low
temperatures (so as to withstand the impact when a filled ice cream
container is dropped). Such "thinwalled" containers are typically prepared
by injection molding.
Injection molding equipment is widely available and is well
described in the literature. The machinery is highly productive, with
molding cycle times often being measured in seconds. These machines
are also very expensive so there is a need to maximize productivity (I.e.
minimize cycle times) in order to control overall production costs.
Productivity may be influenced by the choice of plastic resin used in the
process. In particular, a resin which flows well is desirable to reduce cycle
times.
Flow properties are typically influenced by molecular weight (with
low molecular weight resin having superior flow properties in comparison
to high molecular weight resin) and molecular weight distribution (with
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CA 02413096 2002-11-28
narrow molecular weight resins generally producing molded parts with
reduced warpage in comparison to-broad molecular weight distribution
resins). Copolymer resins of similar molecular weight and molecular
weight distribution generally have higher hexane extractables levels than
homopotymer resins, making them less satisfactory for food applications.
The strength of the finished product over a range of temperatures is
also important. The strength of a finished product may often be increased
by increasing the molecular weight of the resin used to prepare it, but this
is done at the expense of machine productivity. Similarly, the use of a
copolymer resin will often improve the impact strength and flexibility of a
product in comparison to the use of homopoiymer, but at the expense of
extractables content. Thus, a suitable food container which is made at
high "machine productivity" yet also demonstrates good strength
properties at high and low temperatures would be a useful addition to the
art.
SUMMARY OF THE INVENTION
The present invention provides a container having a nominal
volume of from 100 mL to 12 L which is prepared by injection molding of
ethylene copolymer resin, said container having a Vicat softening point of
greater than 121 °C and an average test drop height point of greater
than
2.5 feet as determined by ASTM D5276 wherein said ethylene copolymer
resin is characterized by having:
i) a density of from 0.950 g/cc to 0.955 g/cc;
ii) a viscosity at 100,000 s'' and 280aC of less than 3.5 Pascal
seconds;
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CA 02413096 2002-11-28
iii) a molecular weight distribution, Mw/Mn of from 2.2 to 2.8;
and
iv) a hexane extractables content of less than 0.5 weight %.
Preferred containers also have a total impact energy required for
base failure of greater than 0.2 foot-pounds at -20°C as determined by
Instrumented Impact Testing according to ASTM D3763 (with an
instrument sold under the tradename "INSTRCUN-DYNATUP").
DETAILED DESCRIPTION
We have discovered that thinwalled polyethylene containers having
a Vicat softening point of greater than 121 °C and an average test drop
height of greater than 2.5 feet may be prepared from a linear polyethylene
copolymer resin having all of the following essential characteristics:
1 ) a density of from 0.950 to 0.955 g/cc;
2) a melt index 12, of from 30 to 100 g/10 min as measured by
ASTM D1238 at 190°C;
3) a molecular weight distribution (Mw/Mn) of from 2.2 to 2.8;
4) an apparent viscosity at 100,000 s' and 280°C of less than
3.5 Pascal seconds; and
5) a hexane extractables content of less than 0.5 weight %.
Each of these characteristics is described below.
The density of a polyethylene copolymer is influenced by the
molecular structure of the copolymer. "Linear" homopolymers of ethylene
are rigid molecules that solidify as crystalline resins. Linear ethylene
resins which also have a narrow molecular weight distribution (Mw/Mn,
discussed below) are further characterized by having sharp (distinct)
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CA 02413096 2002-11-28
melting points, which is desirable for injection molding processes.
However, the impact strength of such resins (especialiy at low
temperatures) is poor. The density of a linear ethylene homopolymer
having a narrow molecular weight distribution is generally greater than
0.958 grams per cubic centimeter ("g/cc").
The density of a linear ethylene polymer may be reduced by
incorporating a comonomer (such as butene, hexene, or octene) into the
polymer structure. The comonomers produce "branches" which inhibit
crystal packing and the resulting copolymers generally display improved
impact strengths in comparison to homopolymers. For example, flexible
polyethylene films (not a part of this invention) are typically made from
copolymers having more than 8 mole % comonomer and a density from
about 0.905 to 0.935 g/cc.
The copolymer used in this invention contains a comparatively
small but critical amount of comonomer. The linear ethylene copolymers
must have a density of from 0.950 to 0:955 g/cc. This very specific and
narrow density range is essential in order to obtain high machine
productivity and high strength containers. For the purpose of this
invention, the density of the resin is detem~ined according to ASTM
standard test procedure D792.
The melt index {I2, as determined by ASTM D1238) of the resins
used to prepare the container of this invention must be from 30 to 100 g/10
min. The preferred melt index range is from 50 to 90 g/10 min. The melt
index of a polyethylene copolymer resin is also established by the
molecular structure. Molecular weight is particularly important and is
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CA 02413096 2002-11-28
inversely related to melt index l2. That is, an increase in molecular weight
will generally reduce the ability of the copolymer to flow (and thus cause
an decrease in 12). High melt indices (lower molecular weights) are
desirable to increase machine productivity but high molecular weight is
desirable for strength.
The ethylene copolymer resins used to prepare the containers of
this invention are further characterized by having a molecular weight
distribution (as determined by dividing the weight average molecular
weight "Mw" by the number average molecular weight "Mn") of from 2.2
to 2.8.
Molecular weight determinatians (Mw and Mn) are made by high
temperature gel permeation chromatography (GPC} using techniques
which are well known to those skilled in the art. It will be recognized by
those skilled in the art that different GPC equipment and/or analytical
techniques sometimes result in slightly different absolute values of weight
average molecular weight (Mw) and number average molecular weight
(Mn) for a given resin. Therefore, the resin used in this invention is
defined by the ratio Mw/Mn.
We have determined that resins having a Mw/Mn of from 2.2 to 2.8
(and the density, 12, viscosity characteristic and hexane extractables level
specified for this invention) provide containers having excellent strength
and allow very good productivity.
The present containers are fabricated from ethylene copolymer
resin which has apparent viscosity of less than 3.5 Pascal seconds when
subjected to a shear rate of 100,000 s' at 280°C.
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CA 02413096 2002-11-28
We have determined that this viscosity range provides strong
containers and high machine productivity. Lower viscosity resins typically
produce containers having inferior strength properties. Viscosity is
measured according to ASTM D3835.
Finally, this invention uses a resin having a hexane extractables
content (as determined by ASTM D5227) of less than 0.5 weight %.
The containers of this invention must be made from ethylene
copolymer resin which satisfies all of the above criteria. Such resin may
be prepared using the polymerization catalyst and polymerization process
which is described in United States Patent 6,342,864 (Brown et al.).
Further details of the invention are provided in the following non-limiting
examples.
EXAMPLES
Part 1: Test Procedures Used in The Examples
1. "Instrumented Impact Testing" was completed using a commercially
available instrument (sold under the tradename "INSTRON-DYNATUP")
according to ASTM D3763.
2. Melt Index: 12 and Is were determined according to ASTM D1238.
3. Stress exponent is calculated by log(I6/12) .
log(3)
4. Number average molecular weight (Mn), weight average molecular
weight (Mw), z-average molecular weight (Mz) and polydispersity
(calculated by Mw/Mn) were determined by high temperature Gel
Permeation Chromatography ("GPC").
5. Flexural Secant Modulus and Flexural Tangent Modulus were
determined according to ASTM D790.
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CA 02413096 2002-11-28
6. Elongation, Yield and Tensile Secant Modulas measurements were
determined according to ASTM D636.
7. Hexane Extractables were determined according to ASTM D5227.
8. Densities were determined using the displacement method
according to ASTM D792,
9. "Drop Testing" was completed according to ASTM D5276.
Part 2: Preparation of an Infection Molded Container
For the resins in Example 1, containers were prepared using an
injection molding apparatus sold under the tradename Husky LX 225
P60/60 E70. The mold used for these samples was a 4-cavity mold
making containers with a nominal outside diameter of 4.35 inches (11.0
cm), a thickness of 0.025 inches (0.6 mm) and a volume of 750 mL.
Details of the Husky LX 225 P60/60 E70 thin wall injection molding (T1NIM)
machine are below:
Husky X 225 P60/50 E70
Clamp: 250 tons
Plunger: 50 mm
Screw: 70 m m
Screw UD Ratio: 25:1
Melt Channel Diameter: 8 mm
Conventional barrel temperatures for this apparatus typically range
from 150 to 300°G. For the resins in Example 1, barrel temperatures
ranged from 200 to 250°C, depending on the position in the barrel,
Details
on temperatures and other molding conditions are tabulated in Example 1.
Part 3: Preaaration of an Infection Molded Lid
The machine sold under the tradename Husky LX 225 P60/60 E70
was also used for the resins in Example 2. The mold used for these
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8
CA 02413096 2002-11-28
samples was a 6-cavity mold making round lids for the containers
produced in Example 1. The lids produced have a nominal outside
diameter of 4.68 inches (11.9 cm) and a thickness of 0.04 inches (1.0
mm). Barrel temperatures were cooler than for the resins in Example 1, at
200 to 230°C. Details on temperatures and other molding conditions are
tabulated in Example 2.
Example 1
Inventive resins E1 and E2 were characterized and compared to
three commercially available resins used in this application (Table 1). E1
is a higher molecular weight, broader molecular weight distribution resin
while E2 provides the lowest molecular weight and narrowest molecular
weight distribution of the five resins studied. The data in Table 1 were
collected using conventional ASTM testing techl~iques on resin pellets and
compression molded plaques.
TABLE 1
Characterization of Experimental Container Resins E1 & E2 vs
Benchmarks*
Units C1 E1 C2 C3 E2
ensi cm 0.94930.95160:95130:95360.9517
1Q 56 69 73 86 95
min
is 10 265 268 280 323 352
min
Stress Ex onent 1.43 1.24 1.23 1.21 1.19
Iz~ 10 836 838 772 805 834
rnin
Melt Flow Ratio 15 12 10.5 9.3 8.81
Viscosi X100000 sec Pa-sec3.6 3.9 4.2 3.8 3.9
G~250C
iscosit x:100000 Pa-sec3.1 3.4 3.4 3.4 3.4
sec X280C
o. Ave. Mol. Wt. x 1.0-10.3 13.1 9.8 10.4 13.9
Mn
t. Ave. Mol. Wt. x 10- 40:8 34.6 35.3 34.0 32.3
Mw
Ave. Mol. Wt. Mz x 10- 152.5 75.8 77.2 70.4 59.7
Pol dis ers' Index 3.96 2.64 3.58 3.27 2.32
Hexane Extractables % 0.81 0.24 0.78 0.70 0.29
Melting Poirit C 126.7 128.9128:1 128.0 129.0
stallini % 71:7 75.9 69.3 69.0 81.4
icat Softening PointC 1 i _ i21 122 124
9 _ ~
124
Shore D Hardness 66.4 67.2 66.3 66.1 67.2
Flex. Sec Modules, MPa 934 1128 1177 1208 1161
1%
Flex. Sec Modules, MPa 809 994 1024 1058 1010
2%
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CA 02413096 2002-11-28
Flexural Stren th MPa 27.9 35.2 33.1 35.6 35.5
field Elon ation % 6 15 7 8 11
field Stren th MPa 23.5 26.8 25.3 27.8 26.3
Ultimate Elon ation % 7 24 7 8 12
Ultimate Stren th MPa 23.7 25 25.3 27.8 26.3
ensile Im act ft-Ib/in9.39 38 23.5 21.7 22.6
hiteness Index 79.21 91.3 87. 90 9i
58 .38
ellowness Index -3:31 -7.23-_ ( -6.56_
_ ~ _
( -7.04
-6.22
-
'Physical test data from compression moldedplaaues.
Ci is a polyethylene resin sold under the tradename Equistar H5057.
C2 is a polyethylene resin sold under the tradename SCL.AIR 2815.
C3 is a polyethylene resin sold under the tradename SClJIIR 2717.
The data in Table 1 show that the experimental resins provide by
far the lowest hexane extractable content, making them suitable for food
applications. Their higher crystallinity, Vicat softening point, Shore D
hardness and Flexural Modulus suggest their suitability for higher
1 ~ temperature filling and capping operations, (e.g. ricotta cheese). This
data
set also shows that the experimental resins should provide equivalent
toughness and better color in comparison to incumbent products used in
this market.
Container products were produced using the five resins in Table 1.
They were produced on the Husky injection molding unit described above
using the conditions listed in Table 2.
TABLE 2
Units C1 Ei C2 C3 E2
Resin S ecs
~
MI /10 56 69 73 86 95
min
Dens' em 0.94930.95160.95 0.95360.9517
13
S.Ex. 1.43 i.24 _ 1.21 1.19
1.23
MIC Settin s
Fill ressure % 78 78 78 78 78
Hi h S eed enablemm 70 70 70 70 70
start
Hi h S eed enablemm 30 32 30 34 36
sto
Pullback mm 12 12 12 12 25
Gate heat % on 75 75 75 75 50
Barrel temperatureC 200 200 200 200 200
Zone 1
Barrel temperatureC 210 210 210 210 210
Zone 2
Barrel temperatureC 220 220 220 220 220
Zone 3
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CA 02413096 2002-11-28
Barrel temperatureC 230 230 _._230230 230
Zone 4
Barrel temperatureC 250 250 250 250 250
Zone 5
Variables
Shot wei ht t 04.09104.36 104.25104.47104_.77_
C cle time sec 5.78 5.80 5.88 5.81 5:80
In'ection time sec 0.36 0.39 0.41 0.39 0.40
Screw run time sec 2.11 2.03 2.03 2.06 2.07
Screw back res si 245 245 248 254 248
Ext. drive res si 1059 1115 1131 1085 1045
Max. in'. Pres si 2236 2219 2230 2217 2205
Hold ressure si 1088 1087 1087 1088 1088
Zone 1
Hold ressure si 635 636 637 631 _630
Zone 2
Hold ressure l 301 303 304 302 302
Zone 3
Barrel temperatureC 200 200 200 197 200
Zone 1
Barrel temperatureC 211 211 2i 208 _211
Zone 2 l _
Barrel temperatureC 22i 221 221 221 22i
Zone 3
Barrel temperatureC 230 230 230 230 _23_0
Zone 4
Barrel temperatureC 251 251 251 251 251
Zone 5
in a conventional injection molding cycles the molten resin is
injected into a closed mold which is water cooled. It is desirable to
maximize the productivity of these expensive machines, while also
reducing energy requirements. In order to achieve this, the resin must
have excellent theological properties so that the resin flows sufficiently to
completely fill the mold.
Table 2 provides data which show that the resin E2 from Example 1
requires lower pressure to mold a part. As a result, the barrel
temperatures may be lowered in order to reduce energy consumption
while maintaining cycle time. Conversely, temperatures could be
maintained with a reduced cycle time, thus increasing the molding unit's
unit productivity.
Conventional resins used in thin wall injection molding (l'UIIIM)
container applications are typically of medium to high density and also
exhibit higher molecular weight than resins used in thin wall injection
molding (TWIM) lid applications. The typical tradeoff in these applications
is that if a stiffer product is desired, density is increased at the expense
of
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CA 02413096 2002-11-28
product toughness. Similarly, if better product toughness is desired, the
density of the resin is reduced somewhat and molecular weight of the resin
is also increased, lowering the melt index and making the resin more
difficult to process.
Extensive physical testing of the containers yielded the data in
Table 3. It is clear that in general, the superior properties of the
experimental resins predicted in Table 1 follow through to the injection
molded parts. What is surprising is that the experimental resins, (while
providing equivalent stiffness, as indicated by the retention of density for
7 0 various positions on the part relative to the maximum density available,
i.e.
pellet density}, also provide enhanced toughness, both at low and ambient
temperature. This "decoupling" of the stiffness/toughness balance
appears to apply at both lower and higher melt index. This is illustrated by
the part drop test data; as defined by ASTM D5276. It shows that the
experimental resins provide a pass at nearly twice the height of the
incumbent resins.
TABLE 3
Infection Molded Containers
UnitsC1 E9 C2 C3 E2
Pellet f?ensi cm 0.94930.95160.9513Q.95360.9617
Melt Index i2 10 56 69 73 86 95
miry
Melt index Is 10 265 268 280 323 352
min
Stress Ex onent 1.43 1.24 i.23 1.21 1.19
Part Densi ate /cm 0.941 0.94290.94240:94280.943
mid floor cm 0.93990.94190.94110.94120.942
ste cm 0.94 0.94210.94130:94140.9421
skirt cm 0.94050.94270:94120.9430.9428
Melt index 12 10 55 71 _ 8i 93
min 70
Melt Index IB 10 266 281 269 296 328
min
Stress E onent 1.44 1.25 1.23 1.18 1:15
Tensile Pro erties
MD Eton . at Yield % 17 14 17 17 14
Yield Stren th MPa 18 21.1 19.9 19.9 21.5
Ultimate Elon . % 650 i 093 1138 391 1077
Ultimate Stren th MPa 18.8 19.7 18.8 13.9 16.9
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CA 02413096 2002-11-28
TD Elon . At Yield % 15 12 15 l 6 13
Yield Stren h MPa 10.8 13.2 11.6 12 12.9
Ultimate Elon . % i85 423 337 197 325
.
Ultimate Stren th MPa 10.8 13.2 11.6 12 12.9
lm act Testin
Max. Load ~ 23C Ib 121 118 122 119 117
on wall
Total Ener C 23C ft-Ib 2.85 3.59 2.04 1.82 3.06
on wall
Max. Load ~ -20C Ib 165 153 159 151 148
on wall
Total Ener ~ -20C ft-Ib 2.84 2.44 2.52 2.05 3.25
on wall
Max. Load Cap 23C Ib 14 11 12 12 24
on boftom
Total Ener ~ 23C ft-Ib 0.51 0.42 0.4 0.42 0.46
on bottom
Max. Load ~ -20C Ib 19 10 15 13 30
on bottom
Total Ene C3 -20C ft-Ib O. 0.31 0.1 0.16 _0._23_
on boftom l l
1
Initial Tear Resistance
MD Load At Max. N 66.4 .3 _72.7_61 54.5
68
Stress At Max. N/mm l 03.1_ l 95.5 89.5
_ 12.9
107.2
~ Strain At Max. % 16.7 4.5 6.6 4.3 2.5
TD Load At Max. N 89 94 95.2 82,6 64.5
Stress At Max. N/mm 139.1 148.1153.6126.1 105
Strain At Max. % 66.4 68.7 74.1 38.9 5.5
Whiteness Index 77:58 88.8486.5788.32 87.26
art
Yellowness Index =4..76-8.3 -8,82-9.76 -7:89
art
Part Drop Test
Bruceton Staircase
Ave. Pass Dro Hei ft 1.6 2.7 1.5 1.3 2.6
ht
Max Pass Hei ht ft 3 5 3 3 5
Min Pass Hei ht ft 1 1 1 1 1
Part Shrinka s; % 2.15 1.82 2.12 2.11 1.80
72 hours
Example 2
Parallel to Example 1, Table 4 provides characterization results of
experimental resins E3 and E4 in comparison to four competitive grades in
the TWIM lid market. In similar fashion to the container resins, the
experimental lid resins have significantly lower extractabies content
making them well suited for food applications. They also provide
equivalent crystallinity at a lower melting point along with a higher Vicat
softening point temperature and equivalent Shore D hardness. This
combination of properties suggests lids produced from these resins would
be suitable for hot fill applications, such as those described above for the
experimental container resins. They also appear to have equivalent or
slightly better toughness and equivalent color properties.
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CA 02413096 2002-11-28
TABLE 4
Units C4 C5 G6 E3 G7 E4
Densi cm 0.93110.93190.93540.93240.93080.9321
l2 I10 min 117 i18 1 150 156 168
32
Is 454 _ _ 535 600 670
min 458 _
525
_ __ _ __ _ 1.24 1.24 1.28 1.16 1.23 1.26
Stress
Ex onen
t
_ 665 844 820 840 845 846
_
12~ 10 min
Melt Flow Ratio 5.7 7.2 6.1 5.57 5.4 5.06
__ _ _ 3.5 2.9 3.7 3:3 2.8
Visc 3.6
C~2100
00O s
ec~ C~230C Pa-sec
osi
_ 3.2 3 2.7 3.3 2.8 2.6
_
_
_
Viscosit X100000 sec ca?250C
Pa-sec
No. Ave. Mol. Wt. Mn x 10.0 9.1 8.3 10.6 10.5 9.1
10'
Wt. Ave. Mol. Wt. Mw x 30.0 29.7 30.7 28.6 28.4 29.2
10'
Z Ave. Mot. Wt. Mz x 10' 60.6 60.4 74.3 51.2 55.9 67.3
Pot dis ersi Index 3.00 3.27 3.72 2.70 2.70 3.20
Hexane Extractables wt 3.50 3.27 4.49 0:87 2.26 1.30
%
Melting Point C 122.2123.6125.8119.5124.0i
19.0
C tallin' % 44.0 52.4 56.6 63.7 55.9 '
56.8
Vicat Softening Point C 90 87 96 104 96 101
Shore D Hardness 57.1 59.5 60.3 59.6 59.6 60.2
Flex. Sec Modutus, 1 % 475 627 631 569 498 534
MPa
Flex. Sec Modulus, 2% MPa 444 577 580 513 464 486
Flex. Stren h MPa 17.1 21.3 21 20.5 17.7 19.9
Yield Elon ation % 11 10 11 1 13 17
B
YieldStre_n _ MPa 15 15.7 16.6 16.6 15 16.2
Uttimat_e Elo_n ation % 40 36 76 54 47 46
_
Ultimate Stren th MPa 12.9 12.7 11.1 9.3 12.9 12.6
Tensile Im act ft-Ib/in 34.9 37.8 40.i 49.8 42.8 43.6
Whiteness Index 80.0887.2590.2984.1778.2985.15
Yellowness Index -9.05-10:15-10.72-9.31-8.22-9.98
5 *Physical test data from compression molded plaques.
C4 is a polyethylene resin sold under the tradename SCLAIR 2813.
C5 is a polyethylene resin sold under the tradename Equistar 5947.
C6 is a polyethylene resin sold under the tradename DNDA 1081.
C7 is a polyethylene resin sold under the iradename Dowtex 2507.
10 Lid products were produced using the six resins in Table 4. They
were produced on the Husky injection molding unit mentioned above
under the conditions listed in Table 5. These data indicate that the
experimental resins process very similarly to the incumbent resins. In
addition, the resin E4 requires lower pressure to mold a part. As a result,
the barrel temperatures may be towered in order to reduce energy
consumption while maintaining cycle time, or cycle time reduced at the
same temperature.
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CA 02413096 2002-11-28
TAB LE 5
Huskv Infection Molding Machine Settings and Variables for Molding
Lid Resins
Units C4 C5 C6 E3 C7 E4
Resin S ecs
MI 10 117 118 132 150 156 168
Densi min 0.93110.93190.9354 0.93240.93080.9321
S.Ex. cm 1.24 1.24 1.28 1.16 1,23 1.26
MIC Settin s _ _
Fill ressure % 65 55 55 50 55 50
Pullback mm 0 10 10 10 10 10
Hold ressureZone % 20 20 20 20 20 20
1
Hold ressure Zone_ 15 15 15 15 15
2 % 15
Hold ressure Zone 10 _ _ t0 _
3 / _ _ 10
10 10
10
Barrel tem erature_ _ _ _ 200 200
Zone l _ 204 _ _
_ 200 _
C 200 200
Barrel tem eratureC 210 210 210 210 210 210
Zone 2
Barref tem eratureC 22.0 220 _ 220 220
Zone 3 220 220
Barrel tem ratureC 230 230 230 230 230 230
Zone 4
Barrel tem ratureC 230 230 230 230 230 230
Zone 5
Variables
Shot wei ht 55.85 55.73 55.73 55.7455.7355.80
C cle time sec 4.82 4.84 4.83 4.84 4.83 4.81
In'ection time sec 0.37 0.37 0.36 0.38 0.37 0.36
Screwruntime sec 1.40 1.32 1.40 1.40 i.44 1.56
_ _ 257 255 258 255 257 255
Screw back res l
Ext. drive res si 867 888 827 882 818 767
Max. in'. Pres s't 851 845 778 832 770 725
Hold ressure z.1 l 545 426 426 376 422 375
Hold ressure z.2 si 271 271 271 270 270 271
Hold ressure z.3 si 220 221 223 220 220 221
Barrel temperatureC 200 197 199 197 200 200
Zone 1
Barrel temperatureG 209 207 209 208 2i 2ii
Zone 2 1
Barrel temperatureC 220 219 219 220 221 221
Zone 3
Barrel temperatureC 230 227 228 229 230 230
Zone 4
Barrel temperatureC 230 229 229 231 230 230
Zone 5
Extensive physical testing of the lids yielded the data in Table 6.
These data show that the experimental resins E3 and E4 retain their
stiffness properties and provide excellent toughness. Additionally, these
experimental resins provide vastly superior clarity. This clarity is apparent
for the two experimental resins based on testing using ASTM D1003
(Table 6}. Thus, text placed a short distance behind lids made from any of
the incumbent resins is not even discernible; let alone legible, yet can be
clearly read when placed a similar distance behind a lid made from the
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CA 02413096 2002-11-28
either of the experimental resins. At smaller distances, such as might
occur in packaging a product like yogurt or coffee with a printed foil seal
beneath the lid, this effect is less dramatic. However, the improved clarity
would allow a customer to more easily read the label and thus make the
product more attractive.
TAB LE 6
Infection Molded Lids
Units C4 C5 C5 E3 C7 E4
-!
Pellet Densi cm 0.93110.93190.93540.93240.93080.9321
Melt Index 12 10 1 118 132 150 156 168
min i7
Melt Index is 10 454 458 525 535 600 670
min
Stress Ex onent 1.24 1.24 1.28 1.16 1.23 1.26
Part Dens' ate cm 0.92670:92690.9264Ø92760.92590.9274
mid floor /cm 0.92560,92640.92560:92670.92530.9265
sfe cm 0.92540.9260.92540.92650.92490.9265
skirt cm 0.92570.92680.92610.92760.92580.9271
Melt Index t2 t0 118 114 129 148 152 171
min
Melt Index Is 10 458 444 515 534 571 676
min
Stress E onent 1.24 1.24 1.26 1.17 1.21 1.25
Tensile Pro erties
MD Elon . at Yield% 23 22 21 19 24 20
Yield Stren th MPa 10:4 11.2 12.4 12 10.6 11.6
Ultimate Eton . % 238 209 318 337 287 312
Ultimate Stren MPa 9 9.4 9.6 9.8 8.9 9.6
th
TD Elon . at Yield% 21 20 20 20 22 20
Yield Stren th MPa 10.8 11.5 12 11.9 10.2 11.9
Ultimate Eton . % 94 149 469 l 141 234
03
Ultimate Stren MPa 9.8 8.6 8.8 8.6 8.4 9
th
Im act Testin
Max. Load G~ 23C Ib 99 97 105 107 101 105
on Gate
Total Ener ~ 23C ft-Ib 3.06 3:07 3.27 3.19 3.14 3.2
on Gate
Max. Load (~ -20C Ib 149 144 151 103 114 152
on Gate
Total Ener ~ -20G ft-Ib 4.9 5:13 5.23 2.86 4.17 5.4
on Gate
Max. Load C~ 23C Ib 93 92 87 94 100 93
off Gate
Total Ener ~ 23C ft-Ib 2.62 2.74 2.7 2.92 3.04 2.82
oft Gate
Max. Load ~ -20C 1b 141 153 145 149 160 130
oft Gate
Total Ener Cal ft-Ib 4.61 5.64 4.95 5.41 5.65 5.14
-20C oft Gate
Initial Tear Resistance
MD Load At Max. N 55.3 57.7 63 65.6 57.4 61.2
Stress At Max. N/mm 77.8 81.1 89.3 92.2 80.6 86.1
Strain A# Max. % 17.3 23.2 41.3 15.9 42.1 16.8
TD Load At Max. N 53:3 54.8 61.1 61.8 55.8 59.6
Stress At Main. N/mrn 79:5 81.1 89.7 92.1 82.6 90.2
Strain At Max. % 44.2 32.8 37 35.9 62.2 26.4
Whiteness Index 72.4975.2681.2 77.3674.52 75.64
w1, art
Yellowness index, -15.94-12.76-15.56-8.62-13:69-8.57
YI art
Gloss % 54 54 54 55 54 55
Haze % 87._393.9 94.5 78 90.9 81.1
Clarit % 13 20 7 98 15 98
Part Shrinka e, % 1.82 1.82 1.87 1.78 1 81 1
96 hours 79
M:ISCOtt~PSCSpec19250can.doc
