CA2413096C - Thin walled polyethylene container - Google Patents
Thin walled polyethylene container Download PDFInfo
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- CA2413096C CA2413096C CA2413096A CA2413096A CA2413096C CA 2413096 C CA2413096 C CA 2413096C CA 2413096 A CA2413096 A CA 2413096A CA 2413096 A CA2413096 A CA 2413096A CA 2413096 C CA2413096 C CA 2413096C
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
- B65D1/00—Containers having bodies formed in one piece, e.g. by casting metallic material, by moulding plastics, by blowing vitreous material, by throwing ceramic material, by moulding pulped fibrous material, by deep-drawing operations performed on sheet material
- B65D1/22—Boxes or like containers with side walls of substantial depth for enclosing contents
- B65D1/26—Thin-walled containers, e.g. formed by deep-drawing operations
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/0001—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor characterised by the choice of material
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
- B29K2023/04—Polymers of ethylene
- B29K2023/06—PE, i.e. polyethylene
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
- B29L2031/00—Other particular articles
- B29L2031/712—Containers; Packaging elements or accessories, Packages
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F110/00—Homopolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
- C08F110/02—Ethene
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/13—Hollow or container type article [e.g., tube, vase, etc.]
- Y10T428/1352—Polymer or resin containing [i.e., natural or synthetic]
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- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Mechanical Engineering (AREA)
- Manufacture Of Macromolecular Shaped Articles (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Injection Moulding Of Plastics Or The Like (AREA)
- Containers Having Bodies Formed In One Piece (AREA)
- Packging For Living Organisms, Food Or Medicinal Products That Are Sensitive To Environmental Conditiond (AREA)
Abstract
Thin walled polyethylene containers are suitable for the packaging of foods such as cottage cheese, ricotta cheese and ice cream. The containers have a higher softening point (which permits the containers to be "hot filled") and high impact strength at low temperature (which is useful when a container of ice cream is dropped).
Description
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 M:lScott~PSCSpec~9250can.doc 2 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
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 M:lScott~PSCSpec~9250can.doc 2 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;
M:\ScottIPSCSpec19250can.doc 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;
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;
M:\ScottIPSCSpec19250can.doc 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) M:\ScotNPSCSped9250cen.aoc 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 M:~SCOtHPSCSpec19250can.doC 5 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.
M:\Scott\PSCSpec\J250can.doc 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.
M:lScottIPSCSpec18250can.doc 7
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) M:\ScotNPSCSped9250cen.aoc 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 M:~SCOtHPSCSpec19250can.doC 5 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.
M:\Scott\PSCSpec\J250can.doc 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.
M:lScottIPSCSpec18250can.doc 7
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 nn:~s~o,~scs~sz~o~r,.ao~
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.
Characterization of Experimental Container Resins E1 & E2 vs Benchmarks*
Units C1 E1 C2 C3 E2 ensi cm 0.94930.95160:95130:95360.9517 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 _ ~
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%
M:1S°oriIPSCSpec~9250can.do°
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.
Units C1 Ei C2 C3 E2 Resin S ecs ~
min Dens' em 0.94930.95160.95 0.95360.9517 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 M:vs°on~PSCS~.as2soo~.a°° 10 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 M:\Scott\PSCSpec\9250can.doc 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.
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 AA:lScott~PSCSpec19250can.doc 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 Initial Tear Resistance MD Load At Max. N 66.4 .3 _72.7_61 54.5 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.
M:\Scott~PSCSpec19250can.do°
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 Is 454 _ _ 535 600 670 min 458 _ _ __ _ __ _ 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
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 nn:~s~o,~scs~sz~o~r,.ao~
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.
Characterization of Experimental Container Resins E1 & E2 vs Benchmarks*
Units C1 E1 C2 C3 E2 ensi cm 0.94930.95160:95130:95360.9517 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 _ ~
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%
M:1S°oriIPSCSpec~9250can.do°
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.
Units C1 Ei C2 C3 E2 Resin S ecs ~
min Dens' em 0.94930.95160.95 0.95360.9517 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 M:vs°on~PSCS~.as2soo~.a°° 10 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 M:\Scott\PSCSpec\9250can.doc 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.
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 AA:lScott~PSCSpec19250can.doc 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 Initial Tear Resistance MD Load At Max. N 66.4 .3 _72.7_61 54.5 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.
M:\Scott~PSCSpec19250can.do°
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 Is 454 _ _ 535 600 670 min 458 _ _ __ _ __ _ 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.
nn:~s°°nv~scs~~so~~.do° 14 Huskv Infection Molding Machine Settings and Variables for Molding Lid Resins Units C4 C5 C6 E3 C7 E4 Resin S ecs 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 Hold ressure Zone_ 15 15 15 15 15 2 % 15 Hold ressure Zone 10 _ _ t0 _ 3 / _ _ 10 Barrel tem erature_ _ _ _ 200 200 Zone l _ 204 _ _ _ 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 M:lScoriIPSCSpec19250can.doc 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.
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 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
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.
nn:~s°°nv~scs~~so~~.do° 14 Huskv Infection Molding Machine Settings and Variables for Molding Lid Resins Units C4 C5 C6 E3 C7 E4 Resin S ecs 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 Hold ressure Zone_ 15 15 15 15 15 2 % 15 Hold ressure Zone 10 _ _ t0 _ 3 / _ _ 10 Barrel tem erature_ _ _ _ 200 200 Zone l _ 204 _ _ _ 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 M:lScoriIPSCSpec19250can.doc 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.
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 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
Claims (3)
1. A container having a nominal volume of from 100 mL to 12 L
prepared by injection molding of ethylene copolymer resin, said container having 1) a Vicat softening point of greater than 121°C and 2) an average test value of greater than 2.5 feet as determined by ASTM D5276 wherein said ethylene copolymer resin is characterized by:
i) a density from 0.950 g/cc to 0.955 g/cc;
ii) a viscosity at 100,000 sec-1 shear rate and 280°C of less than 3.5 Pascal seconds;
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 %.
prepared by injection molding of ethylene copolymer resin, said container having 1) a Vicat softening point of greater than 121°C and 2) an average test value of greater than 2.5 feet as determined by ASTM D5276 wherein said ethylene copolymer resin is characterized by:
i) a density from 0.950 g/cc to 0.955 g/cc;
ii) a viscosity at 100,000 sec-1 shear rate and 280°C of less than 3.5 Pascal seconds;
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 %.
2. The container of claim 1 which is further characterized by having a total impact energy required for wall failure of greater than 3.0 foot-pounds at 23°C.
3. The container of claim 1 which is further characterized by having a total impact energy required for base failure of greater than 0.20 foot-pounds at -20°C as determined by ASTM D3763.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA2413096A CA2413096C (en) | 2002-11-28 | 2002-11-28 | Thin walled polyethylene container |
| US10/706,336 US20040105944A1 (en) | 2002-11-28 | 2003-11-12 | Thin walled polyethylene container |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA2413096A CA2413096C (en) | 2002-11-28 | 2002-11-28 | Thin walled polyethylene container |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2413096A1 CA2413096A1 (en) | 2004-05-28 |
| CA2413096C true CA2413096C (en) | 2010-12-21 |
Family
ID=32331655
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2413096A Expired - Lifetime CA2413096C (en) | 2002-11-28 | 2002-11-28 | Thin walled polyethylene container |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US20040105944A1 (en) |
| CA (1) | CA2413096C (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ATE492575T1 (en) | 2005-05-10 | 2011-01-15 | Ineos Europe Ltd | NEW COPOLYMERS |
| US8486323B2 (en) | 2009-08-28 | 2013-07-16 | Dow Global Technologies Llc | Rotational molded articles, and method of making the same |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5792534A (en) * | 1994-10-21 | 1998-08-11 | The Dow Chemical Company | Polyolefin film exhibiting heat resistivity, low hexane extractives and controlled modulus |
| US5811494A (en) * | 1995-04-06 | 1998-09-22 | The Dow Chemical Company | Impact modified thinwall polymer compositions |
| CA2245375C (en) * | 1998-08-19 | 2006-08-15 | Nova Chemicals Ltd. | Dual reactor polyethylene process using a phosphinimine catalyst |
-
2002
- 2002-11-28 CA CA2413096A patent/CA2413096C/en not_active Expired - Lifetime
-
2003
- 2003-11-12 US US10/706,336 patent/US20040105944A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| CA2413096A1 (en) | 2004-05-28 |
| US20040105944A1 (en) | 2004-06-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKEX | Expiry |
Effective date: 20221128 |