CA2092968C - Multi-layered thermoplastic packaging film with improved oxygen permeability - Google Patents
Multi-layered thermoplastic packaging film with improved oxygen permeability Download PDFInfo
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- CA2092968C CA2092968C CA 2092968 CA2092968A CA2092968C CA 2092968 C CA2092968 C CA 2092968C CA 2092968 CA2092968 CA 2092968 CA 2092968 A CA2092968 A CA 2092968A CA 2092968 C CA2092968 C CA 2092968C
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Abstract
A multilayer film characterized by having excellent oxygen permeability and thermoformable properties compris-ing a sealant layer and a heat resistant layer is dis-closed. The sealant layer contains an ethylene based poly-mer or copolymer. The heat resistant layer has a melting point greater than that of the polymeric composition of the sealing layer. Internal layers may also be provided.
Description
- ' -- 2092968 MULTI-LAYERED THERMOPLASTIC PACKAGING FILM
WITH IMPROVED OXYGEN PERMEABILITY
Background of the Invention The present invention relates to a multi-layer film which is particularly useful as packaging material. More ' specifically, this invention relates to an oxygen permea-ble, thermoformable, multilayer film especially useful for packaging products that require oxygen such as fresh poul-try and frozen red meat.
Description of the Prior Art Numerous film products are employed for packaging and for delivery of food products. These films were developed to have particular properties and often employ multiple layers to obtain the desired properties. For example, it is well known to use polyolefin based films which are char-acterized by high strength, excellent moisture and water vapor resistance, fair chemical resistance and variable processability. These polymers are often used in combina-tion with other polymers. It has been found that no single polymer or copolymer however can possess all the desired properties and thus the proper combination of different polymers and multilayered structures have been found to provide a good balance depending on the end use of the film.
Many fiLas designed for packaging applications in the food industry incorporate "barrier" polymers to prevent the 5/920821.5/SPECFLDR
passage of oxygen. The present invention however is direct-ed to films to be used for packaging certain food products such as fresh poultry which must necessarily possess high oxygen permeability.
For many such packaging applications it is also desir-able that the oxygen permeable film is capable of thermoforming. Most typically, a non-thermoforming film or web will be used in combination with a thermoforming film or web to produce a final package. In a typical operation a forming web is formed into a mold to provide a film cavi-ty in Which a food product is placed. A non-forming web can then be placed over the cavity and vacuum sealed by means well known in the art to the periphery of the forming web. Many meat products are packaged in this manner.
A prior art non-thermoformable web is available which employs biaxially oriented polypropylene as an outermost heat resistant layer. However, heretofore there has been only one commercially available thermoformable film having good oxygen permeability properties. That is, it is gener-ally known that thermoformable mono-layer ionomers provide high oxygen permeability. Generally speaking, ionomers are metal neutralized salts of ethylene acrylic acid or methacrylic acid copolymers and are most typically sold under the trade name Surlyn(TM) by DuPont. Although mono-layer Surlyn produced by a blown or cast process.provides a heat sealable thermoformable oxygen permeable film, product failure rate .is high because the periphery of the web must be heated to its softening point in order for sealing to occur. Thus, burn through is common.
Thus there is a need in the art for a heat-sealable thermoformable oxygen permeable film or web which does not degrade upon sealing.
5/92~821.5/SPECFLDR
WITH IMPROVED OXYGEN PERMEABILITY
Background of the Invention The present invention relates to a multi-layer film which is particularly useful as packaging material. More ' specifically, this invention relates to an oxygen permea-ble, thermoformable, multilayer film especially useful for packaging products that require oxygen such as fresh poul-try and frozen red meat.
Description of the Prior Art Numerous film products are employed for packaging and for delivery of food products. These films were developed to have particular properties and often employ multiple layers to obtain the desired properties. For example, it is well known to use polyolefin based films which are char-acterized by high strength, excellent moisture and water vapor resistance, fair chemical resistance and variable processability. These polymers are often used in combina-tion with other polymers. It has been found that no single polymer or copolymer however can possess all the desired properties and thus the proper combination of different polymers and multilayered structures have been found to provide a good balance depending on the end use of the film.
Many fiLas designed for packaging applications in the food industry incorporate "barrier" polymers to prevent the 5/920821.5/SPECFLDR
passage of oxygen. The present invention however is direct-ed to films to be used for packaging certain food products such as fresh poultry which must necessarily possess high oxygen permeability.
For many such packaging applications it is also desir-able that the oxygen permeable film is capable of thermoforming. Most typically, a non-thermoforming film or web will be used in combination with a thermoforming film or web to produce a final package. In a typical operation a forming web is formed into a mold to provide a film cavi-ty in Which a food product is placed. A non-forming web can then be placed over the cavity and vacuum sealed by means well known in the art to the periphery of the forming web. Many meat products are packaged in this manner.
A prior art non-thermoformable web is available which employs biaxially oriented polypropylene as an outermost heat resistant layer. However, heretofore there has been only one commercially available thermoformable film having good oxygen permeability properties. That is, it is gener-ally known that thermoformable mono-layer ionomers provide high oxygen permeability. Generally speaking, ionomers are metal neutralized salts of ethylene acrylic acid or methacrylic acid copolymers and are most typically sold under the trade name Surlyn(TM) by DuPont. Although mono-layer Surlyn produced by a blown or cast process.provides a heat sealable thermoformable oxygen permeable film, product failure rate .is high because the periphery of the web must be heated to its softening point in order for sealing to occur. Thus, burn through is common.
Thus there is a need in the art for a heat-sealable thermoformable oxygen permeable film or web which does not degrade upon sealing.
5/92~821.5/SPECFLDR
Summary of the Invention It is thus an object of the present invention to provide heat-sealable thermoplastic multilayer film having good oxygen permeability.
It is a more particular object of the present invention to provide a suitable thermoplastic material for packaging fresh poultry or frozen meat.
It is yet another object of the present invention to provide a multilayer thermoplastic film having an oxygen l0 transmission rate greater than 2000 cc. mil/m2-24 hr. atm. at 73°F.
Such objects are generally achieved by providing a multilayer, thermoformable film which includes a sealing layer and an outer heat resistant layer, preferably of a propylene 1S based polymer, wherein the polymeric composition of the outer heat resistant layer has a melting point greater than that of the sealing layer.
Such objects are more particularly achieved by providing such a film wherein the outer heat resistant layer 20 has a melting point at least about 10°F greater than that of the sealing layer.
Thus, there is provided a multilayer film comprising:
an outer heat-sealable layer comprising an ethylene-based polymer; and a polymeric outer heat-resistant layer having a 25 melting point that is at least 10°F greater than the melting point of the heat-sealable layer, wherein the multilayer film is unperforated, thermoformable and has an oxygen transmission rate greater than 2000 cm3 mil/m2-24 hrs atmosphere at 73°F, and wherein all the layers of the film are co-extruded.
It is a more particular object of the present invention to provide a suitable thermoplastic material for packaging fresh poultry or frozen meat.
It is yet another object of the present invention to provide a multilayer thermoplastic film having an oxygen l0 transmission rate greater than 2000 cc. mil/m2-24 hr. atm. at 73°F.
Such objects are generally achieved by providing a multilayer, thermoformable film which includes a sealing layer and an outer heat resistant layer, preferably of a propylene 1S based polymer, wherein the polymeric composition of the outer heat resistant layer has a melting point greater than that of the sealing layer.
Such objects are more particularly achieved by providing such a film wherein the outer heat resistant layer 20 has a melting point at least about 10°F greater than that of the sealing layer.
Thus, there is provided a multilayer film comprising:
an outer heat-sealable layer comprising an ethylene-based polymer; and a polymeric outer heat-resistant layer having a 25 melting point that is at least 10°F greater than the melting point of the heat-sealable layer, wherein the multilayer film is unperforated, thermoformable and has an oxygen transmission rate greater than 2000 cm3 mil/m2-24 hrs atmosphere at 73°F, and wherein all the layers of the film are co-extruded.
64'536-807 Description of Preferred Embodiments The present invention provides a multilayer packaging film characterized by having excellent oxygen permeability and thermoformability properties which includes at least a sealing layer and a heat resistant layer. The sealing layer most preferably includes an ethylene based polymer such as low density polyethylene or a copolymer of ethylene 3a .. 2os~~s~
and one or more comonomers. Preferred ethylene copolymers include ethylene/alpha-olefins, ethylene vinyl acetates, ethylene alkyl acrylates, ethylene acrylic acid copolymers as well as the metal neutralized salts of ethylene acrylic or methacrylic acid copolymers commonly referred to as ionomers.
Ethylene alpha-olefins are, generally speaking, copolymers of ethylene with one or more comonomers selected from C3 to about C1o alpha olefins but especially com-prises ethylene copolymers with C, to about C1o alpha olefins such as butene-1, pentane-1, hexene-1, octene-1, and the like, in which the polymer molecules comprise long ' chains with few side chains or branches and sometimes are referred to as linear polymers. These polymers are ob-tained by low pressure polymerization processes and the side branching which is present will be short compared to non-linear ethylenes. Ethylene/alpha-olefin copolymers have a density in the range of from about 0.860 g/cc to about 0.940 g/cc. The term linear low density~polyethylene is generally understood to include that group of ethylene/alpha-olefin copolymers which fall into the densi-ty range of about 0.915 to about 0.940 g/cc. Sometimes linear polyethylene in the density range from about 0.926 to about 0.940 is referred to a linear medium density poly-ethylene (L2~PE). Lower density ethylene alpha olefins may be referred to as very low density polyethylene (VLDPE, typically used to refer to the ethylene butene copolymers -~ supplied by Union Carbide) and ultra-low density polyethyl-ene (ULDPE, typically used to refer to the ethylene octene copolymers supplied by Dow). It should be noted although specific density ranges is for vLDPE, ULDPE, LLDPE, and LI4aPE have been set forth herein, that no bright line can be drawn for density classification and such will vary by supplier.
5/920821.5/SPECFLDR
and one or more comonomers. Preferred ethylene copolymers include ethylene/alpha-olefins, ethylene vinyl acetates, ethylene alkyl acrylates, ethylene acrylic acid copolymers as well as the metal neutralized salts of ethylene acrylic or methacrylic acid copolymers commonly referred to as ionomers.
Ethylene alpha-olefins are, generally speaking, copolymers of ethylene with one or more comonomers selected from C3 to about C1o alpha olefins but especially com-prises ethylene copolymers with C, to about C1o alpha olefins such as butene-1, pentane-1, hexene-1, octene-1, and the like, in which the polymer molecules comprise long ' chains with few side chains or branches and sometimes are referred to as linear polymers. These polymers are ob-tained by low pressure polymerization processes and the side branching which is present will be short compared to non-linear ethylenes. Ethylene/alpha-olefin copolymers have a density in the range of from about 0.860 g/cc to about 0.940 g/cc. The term linear low density~polyethylene is generally understood to include that group of ethylene/alpha-olefin copolymers which fall into the densi-ty range of about 0.915 to about 0.940 g/cc. Sometimes linear polyethylene in the density range from about 0.926 to about 0.940 is referred to a linear medium density poly-ethylene (L2~PE). Lower density ethylene alpha olefins may be referred to as very low density polyethylene (VLDPE, typically used to refer to the ethylene butene copolymers -~ supplied by Union Carbide) and ultra-low density polyethyl-ene (ULDPE, typically used to refer to the ethylene octene copolymers supplied by Dow). It should be noted although specific density ranges is for vLDPE, ULDPE, LLDPE, and LI4aPE have been set forth herein, that no bright line can be drawn for density classification and such will vary by supplier.
5/920821.5/SPECFLDR
Recently a new type of ethylene based linear polymers have been introduced. These new resins are produced by metallocene catalyst polymerization and are characterized by narrow or more homogenous compositional properties, such as molecular weight distribution, than resins produced by conventional Ziegler-Natta polymerization processes.
Conventional Ziegler-Natta polymerization systems have discreet catalyst composition differences which are mani-fested as different catalyst reaction sites with each site having different reaction rates and selectivities.
Metallocene catalyst systems are characterized as a single identifiable chemical type which has a singular rate in selectivity. Thus the conventional systems produce resins ' that reflect the differential character of the different catalyst sites while resins produced by metallocene systems reflect the single catalytic site. However, it should be noted that at least some previously available, ethylene based linear polymers approximated the physical and composi-tional properties achieved by the present metallocene cata-lyzed polyolefins. That is traditional metallic catalyzed polymerization processes operating at low reaction rates can produce relatively homogenous resins that compare favor-ably with .the homogeneity of metallocene catalyzed resins.
An example of such are the resins sold under the trade name Tafmer(TM) by Mitsui. Both metallocene catalyzed ethylene alpha olefins and the Tafmer-type of resins are appropriate for use in the heat seal layer of the present invention.
Another .resin which may be used in the present heat seal layer is a butadiene styrene copolymer (BDS) such as DR10, one of the R resin series available from Phillips Chemical Company. Also, within the scope of the present heat resistant layer are modified polyvinyl chlorides (PVC) such as supplied by B.F. Goodrich. Inclusion of such res-ins provides stiffness to the overall film structure as well as imparting excellent oxygen permeability qualities.
Conventional Ziegler-Natta polymerization systems have discreet catalyst composition differences which are mani-fested as different catalyst reaction sites with each site having different reaction rates and selectivities.
Metallocene catalyst systems are characterized as a single identifiable chemical type which has a singular rate in selectivity. Thus the conventional systems produce resins ' that reflect the differential character of the different catalyst sites while resins produced by metallocene systems reflect the single catalytic site. However, it should be noted that at least some previously available, ethylene based linear polymers approximated the physical and composi-tional properties achieved by the present metallocene cata-lyzed polyolefins. That is traditional metallic catalyzed polymerization processes operating at low reaction rates can produce relatively homogenous resins that compare favor-ably with .the homogeneity of metallocene catalyzed resins.
An example of such are the resins sold under the trade name Tafmer(TM) by Mitsui. Both metallocene catalyzed ethylene alpha olefins and the Tafmer-type of resins are appropriate for use in the heat seal layer of the present invention.
Another .resin which may be used in the present heat seal layer is a butadiene styrene copolymer (BDS) such as DR10, one of the R resin series available from Phillips Chemical Company. Also, within the scope of the present heat resistant layer are modified polyvinyl chlorides (PVC) such as supplied by B.F. Goodrich. Inclusion of such res-ins provides stiffness to the overall film structure as well as imparting excellent oxygen permeability qualities.
5/920821.5/SPECFLDR
As noted above, ionomers are also within the scope of the present seal layer. As has been seen in the prior art mcnolayer Surlyri films, such resi~ provides excellent heat sealability as well as high oxyge.~. permeability. However, unlike the mono-layer films of the prior art, the present film structure will also include a heat resistant layer such that upon sealing the entire thickness of the film structure is not heated to its sof~,.~ning point.
Accordingly, the present fiL~~ structure includes a heat resistant layer having a melting point greater than that of the sealing layer. Thus, when a non-forming web in accordance with the present invention is positioned above a thermoformed web containing product and sealed about the periphery thereof, the outermost surf aces of each of the two webs need not be heated to ti:e ~ point of softening by the sealing mechanism in order for adequate sealing to occur between the two respective seal layers.
Furthermore, it should be noted that although the present invention is generally directed to thermoformable webs, non-forming webs are also within the scope of the invention. That is, thermoformable webs which are not thermoformed in the end-use application are considered non-forming and are covered by the present invention.
Most preferred for use in the heat resistant layer of the present film structure are propylene based resins such as propylene homopolymers and propylene copolymers.
Ethylene propylene copolymers which have a major portion of prop~rlene and a minor portion of a ~'.'.~.ylene are desirable for use in the present heat resistant layer as such do not become brittle at freezing temperatures. Conventional polypropylenes are desirable because of their high melting point, approximately 160°C, but may become brittle at freez-ing temperatures. Thus, the end-use application as well as the melting point of the polymeric composition of the heat seal layer must be considered in choosing the polymeric composition of the heat resistant layer. Specifically, the heat resistant layer must have a melting point greater than that of the heat seal layer and most preferably at least 10°F greater than that of the heat seal layer.
Other resins appropriate for use in the heat resistant layer include polystyrene and styrene butadiene copolymer.
Although such resins have melting points less than that of polypropylene, they can be employed in accordance with the present invention so long as the polymeric components of the heat seal layer have an even lower melting point.
It has further been found that advantages of different heat resistant polymers may be incorporated into a single structure by incorporating two or more of such resins into a single film, either in separate layers or by blending.
For example, in a preferred embodiment, the outermost layer is a polypropylene but an internal layer is included of an ethylene propylene copolymer (EPC). The internal EPC layer is, of course, more heat resistant than the seal layer but adds a pliancy to the structure not afforded by the more heat resistant but less pliant polypropylene. Thus, crack-ing at freezing temperatures is reduced. Other polymers appropriate for use in the outer heat resistant layer may also be used internally in the structure although it would generally be preferred to provide the mast heat resistant polymeric composition in the outermost layer.
Also within the scope of the present invention are internal tie layers which add bulk and prevent delamination without decreasing the oxygen transmitability of the entire structure. Preferred tie layers include ethylene vinyl acetates, ethylene methyl acrylates, ethylene butyl acry-lates, very low density polyethylenes, ultra low density polyethylenes, Tafmers, as well as metallocene catalyzed ethylene alpha-olefins of lower densities. Generally speak-5/920821.5/SPECFLDR
As noted above, ionomers are also within the scope of the present seal layer. As has been seen in the prior art mcnolayer Surlyri films, such resi~ provides excellent heat sealability as well as high oxyge.~. permeability. However, unlike the mono-layer films of the prior art, the present film structure will also include a heat resistant layer such that upon sealing the entire thickness of the film structure is not heated to its sof~,.~ning point.
Accordingly, the present fiL~~ structure includes a heat resistant layer having a melting point greater than that of the sealing layer. Thus, when a non-forming web in accordance with the present invention is positioned above a thermoformed web containing product and sealed about the periphery thereof, the outermost surf aces of each of the two webs need not be heated to ti:e ~ point of softening by the sealing mechanism in order for adequate sealing to occur between the two respective seal layers.
Furthermore, it should be noted that although the present invention is generally directed to thermoformable webs, non-forming webs are also within the scope of the invention. That is, thermoformable webs which are not thermoformed in the end-use application are considered non-forming and are covered by the present invention.
Most preferred for use in the heat resistant layer of the present film structure are propylene based resins such as propylene homopolymers and propylene copolymers.
Ethylene propylene copolymers which have a major portion of prop~rlene and a minor portion of a ~'.'.~.ylene are desirable for use in the present heat resistant layer as such do not become brittle at freezing temperatures. Conventional polypropylenes are desirable because of their high melting point, approximately 160°C, but may become brittle at freez-ing temperatures. Thus, the end-use application as well as the melting point of the polymeric composition of the heat seal layer must be considered in choosing the polymeric composition of the heat resistant layer. Specifically, the heat resistant layer must have a melting point greater than that of the heat seal layer and most preferably at least 10°F greater than that of the heat seal layer.
Other resins appropriate for use in the heat resistant layer include polystyrene and styrene butadiene copolymer.
Although such resins have melting points less than that of polypropylene, they can be employed in accordance with the present invention so long as the polymeric components of the heat seal layer have an even lower melting point.
It has further been found that advantages of different heat resistant polymers may be incorporated into a single structure by incorporating two or more of such resins into a single film, either in separate layers or by blending.
For example, in a preferred embodiment, the outermost layer is a polypropylene but an internal layer is included of an ethylene propylene copolymer (EPC). The internal EPC layer is, of course, more heat resistant than the seal layer but adds a pliancy to the structure not afforded by the more heat resistant but less pliant polypropylene. Thus, crack-ing at freezing temperatures is reduced. Other polymers appropriate for use in the outer heat resistant layer may also be used internally in the structure although it would generally be preferred to provide the mast heat resistant polymeric composition in the outermost layer.
Also within the scope of the present invention are internal tie layers which add bulk and prevent delamination without decreasing the oxygen transmitability of the entire structure. Preferred tie layers include ethylene vinyl acetates, ethylene methyl acrylates, ethylene butyl acry-lates, very low density polyethylenes, ultra low density polyethylenes, Tafmers, as well as metallocene catalyzed ethylene alpha-olefins of lower densities. Generally speak-5/920821.5/SPECFLDR
ing, most resins suitable f or use in the seal layer will also serve appropriately as tie layer resins. A preferred tie resin is a high vinyl acetate BVA which promotes adhe-sion between the various layers of the film structure.
The following examples are intended to illustrate the pref erred embodiments of the invention.
a v T rm r c~ ~
Sample films were prepared by coextrusion, i.e., all of the layers are extruded at once. The polymer melt from the extrusion dies was cooled and cast into solid sheets having a thickness of 7.46 mils.
P.P. EVA P.P. EVA P.P. EVA LLDPE
22% 12% 7% 6% 7% 8% 38%
P.P. - Quantum Petrothene Polypropylene Homopolymer EVA - Exxon Ethylene Vinyl Acetate LD 720.92 19% V.A.
LLDPE= Dow DowleX Linear Low Density Polyethylene One of the sheets was tested for oxygen permeability on an OX-TRANS Ten-,Fifty Oxygen Permeability Tester (Test Method E-160) and the results for three c~~ts were 1061.8; 1077.4;
and 1037.0 cc/m2/24 hr.-atm, respectively.
The following examples are intended to illustrate the pref erred embodiments of the invention.
a v T rm r c~ ~
Sample films were prepared by coextrusion, i.e., all of the layers are extruded at once. The polymer melt from the extrusion dies was cooled and cast into solid sheets having a thickness of 7.46 mils.
P.P. EVA P.P. EVA P.P. EVA LLDPE
22% 12% 7% 6% 7% 8% 38%
P.P. - Quantum Petrothene Polypropylene Homopolymer EVA - Exxon Ethylene Vinyl Acetate LD 720.92 19% V.A.
LLDPE= Dow DowleX Linear Low Density Polyethylene One of the sheets was tested for oxygen permeability on an OX-TRANS Ten-,Fifty Oxygen Permeability Tester (Test Method E-160) and the results for three c~~ts were 1061.8; 1077.4;
and 1037.0 cc/m2/24 hr.-atm, respectively.
TABLE I
LONGITUDINAL
Specimen Stress at Strain at Modulus Number ~ Max. Load Max. Load ( pSl ) ( >o ) ( PSIXI000 ) 1 4017.5 942.0 34.128 2 405.9 941.5 29.417 3 4020.3 942.0 42.016 Mean 4031.2 941.8 35.187 TRANSVERSE
Specimen Stress at Strain at Modulus Number Max. Load Max. Load (psi) (%) (PSIX1000).
1 3236.9 942.0 41.791 2 3407.0 942.0 43.214 3 3029.8 942.0 42.251 Mean 3224.6 942.0 42.418 'L~ V T M'i~T L~ 7 Another sample film was prepared by blending 93% of LLDPE (DowleXM2044A) and 15% ULDPE (AttaneM4201) with about 2% of a master batch concentrate containing slip and antiblcck additives. The antiblock master batch included AmpacetTM (10853). This heat sealing layer was coextruded into a film structure containing alternating layers of ethylene vinyl acetate and ethylene-~olypropylene copolymer.
Films having the following formulation were cast into sheets having'a thickness of 3.0, 3.5, 5.0 and 11 mils.
LONGITUDINAL
Specimen Stress at Strain at Modulus Number ~ Max. Load Max. Load ( pSl ) ( >o ) ( PSIXI000 ) 1 4017.5 942.0 34.128 2 405.9 941.5 29.417 3 4020.3 942.0 42.016 Mean 4031.2 941.8 35.187 TRANSVERSE
Specimen Stress at Strain at Modulus Number Max. Load Max. Load (psi) (%) (PSIX1000).
1 3236.9 942.0 41.791 2 3407.0 942.0 43.214 3 3029.8 942.0 42.251 Mean 3224.6 942.0 42.418 'L~ V T M'i~T L~ 7 Another sample film was prepared by blending 93% of LLDPE (DowleXM2044A) and 15% ULDPE (AttaneM4201) with about 2% of a master batch concentrate containing slip and antiblcck additives. The antiblock master batch included AmpacetTM (10853). This heat sealing layer was coextruded into a film structure containing alternating layers of ethylene vinyl acetate and ethylene-~olypropylene copolymer.
Films having the following formulation were cast into sheets having'a thickness of 3.0, 3.5, 5.0 and 11 mils.
9$% P.P. EVA EPC EVA EPC EVA 15o ULDPE
2% Amp.l 83% LLDPE
2% Amp.2 12% 10% 13% 70 13% 7% 33%
P.P. - Exxon Escorene Polr~ropylene Homopolymer EVA - Exxon Ethylene Vi:~.rl Acetate LD 720.92 19% V.A.
LLDPE - Dow Dowle.~MLinear Low Density Polyethylene Amp.l - Ampacet~ PP based slip masterbatch AmpacetM 40604 Amp.2 - AmpacetTMLLDPE based masterbarch / Ampacet~' EPC - Exxon Escorene PD9302 3.3% Ethylene 3.8 M.F.
ULDPE - Dow Attane 4201 - 1.0 M.F. 0.912 Density A sheet of 3.0 and 3.5 mil film was tested for oxygen perme-ability on an OX-TRANS Ten-Fifty Cxygen Permeability Tester (Test Method E-160). The resultant transmission rates shown below in Table II are not as high as would be expect-ed, especially in view of the data given on Example 1 for a 7.46 mil film. It is believed that the Permeability Tester employed is somewhat inaccurate at higher permeability.
TABLE II
Oz Transmission Rate (cc/mZ/24hr-atm) SAMPLE 1st Cut 2nd Cu'. 3rd Cut 3.0 mil 1776 1876 1965 3.5 mil 1779 1799 1889 Samples of the 3.0 mil, 3.5 m=1 and 5.0 mil films were tested for tensile strength, eloncation and modulus. The results are shown in the tables below.
TABLE III
LONGITUDINAL'-SpecimenStress Strain at Modulus at Number Max. Load Max. Load (psi) (%) (PSIX1000) 1 5613.0 825.0 31.732 2 6052.8 868.0 28.928 3 6271.0 840. 30.373 Mean 5978.9 844.3 30.345 '- Mean thickness was 2.793 mils.
SpecimenStress at Strain Modulus at Number Max. Load Max.
Load (psi) (%) (PSIX1000) 1 3643.9 941.5 30.595 2 3548.1 941.5 25.263 3 3917.8 94 1.5 29.452 Mean 3703.3 941 .5 28.437 2Mean thickness was 2.940 mils.
TABLE IV
Specimen Stress at Strain Modulus at Number Max. Load Max.
Load (psi) ($) (PSIX1000) 1 6315.6 941.5 33.297 2 6101.6 941.5 32.113 3 6071.0 891.0 39.997 Mean 6162.0 924.7 35.136 1 Mean mils.
thickness was 3.68 TRANSVERSE=
Specimen Stress at Strain Modulus at Number Max. Load Max.
Load (psi) (%) (PSIX1000) 1 3548.6 941.5 35.332 2 3310.8 941.5 28.852 3 3559.3 941.5 25.209 Mean 350 .3 941.5 29.798 Mean thickness was 5.120 mils.
5/920821.5/SPECFLDR
LONGITUDINAL) TABLE V
Specimen Stress Strain Modulus at at Number Max. Max. Load Load (psi) (%) (PSIX1000) 1 3204.4 751.5 26.051 2 3303.6 751.5 29.232 3 4573.1 942.0 30.113 _ Mean 3703.7 815.0 28.455 1 Mean thickness was 5.120 mils.
Specimen Stress Strain Modulus at at Number Max. Max. Load Load (psi) (%) (PSIX1000) ' 1 3491.8 941.5 35.107 2 3395.6 941.5 33.745 3 3484.1 942.5 29.576 Mean 3457.1 941.8 32.809 1 Mean thickness mils.
was 4.980 Although illustrated embodimentsof the invention have been described hereinabove, it is to be under-in detail stood that is not ited to those precise the invention lim embodiments, and modifications may and that various changes be readily rdinary skill without effected by persons of o department of the invention and from the spirit or scope being set forth followinglaims. For example, in the c although it preferred is generally that film structures in accordance are coextruded, films with the present invention which are laminated as by sive lamination, heat such adhe and pressure also within the scope or corona lamination are of the present invention.
5/920821.5/SPECFLDR
2% Amp.l 83% LLDPE
2% Amp.2 12% 10% 13% 70 13% 7% 33%
P.P. - Exxon Escorene Polr~ropylene Homopolymer EVA - Exxon Ethylene Vi:~.rl Acetate LD 720.92 19% V.A.
LLDPE - Dow Dowle.~MLinear Low Density Polyethylene Amp.l - Ampacet~ PP based slip masterbatch AmpacetM 40604 Amp.2 - AmpacetTMLLDPE based masterbarch / Ampacet~' EPC - Exxon Escorene PD9302 3.3% Ethylene 3.8 M.F.
ULDPE - Dow Attane 4201 - 1.0 M.F. 0.912 Density A sheet of 3.0 and 3.5 mil film was tested for oxygen perme-ability on an OX-TRANS Ten-Fifty Cxygen Permeability Tester (Test Method E-160). The resultant transmission rates shown below in Table II are not as high as would be expect-ed, especially in view of the data given on Example 1 for a 7.46 mil film. It is believed that the Permeability Tester employed is somewhat inaccurate at higher permeability.
TABLE II
Oz Transmission Rate (cc/mZ/24hr-atm) SAMPLE 1st Cut 2nd Cu'. 3rd Cut 3.0 mil 1776 1876 1965 3.5 mil 1779 1799 1889 Samples of the 3.0 mil, 3.5 m=1 and 5.0 mil films were tested for tensile strength, eloncation and modulus. The results are shown in the tables below.
TABLE III
LONGITUDINAL'-SpecimenStress Strain at Modulus at Number Max. Load Max. Load (psi) (%) (PSIX1000) 1 5613.0 825.0 31.732 2 6052.8 868.0 28.928 3 6271.0 840. 30.373 Mean 5978.9 844.3 30.345 '- Mean thickness was 2.793 mils.
SpecimenStress at Strain Modulus at Number Max. Load Max.
Load (psi) (%) (PSIX1000) 1 3643.9 941.5 30.595 2 3548.1 941.5 25.263 3 3917.8 94 1.5 29.452 Mean 3703.3 941 .5 28.437 2Mean thickness was 2.940 mils.
TABLE IV
Specimen Stress at Strain Modulus at Number Max. Load Max.
Load (psi) ($) (PSIX1000) 1 6315.6 941.5 33.297 2 6101.6 941.5 32.113 3 6071.0 891.0 39.997 Mean 6162.0 924.7 35.136 1 Mean mils.
thickness was 3.68 TRANSVERSE=
Specimen Stress at Strain Modulus at Number Max. Load Max.
Load (psi) (%) (PSIX1000) 1 3548.6 941.5 35.332 2 3310.8 941.5 28.852 3 3559.3 941.5 25.209 Mean 350 .3 941.5 29.798 Mean thickness was 5.120 mils.
5/920821.5/SPECFLDR
LONGITUDINAL) TABLE V
Specimen Stress Strain Modulus at at Number Max. Max. Load Load (psi) (%) (PSIX1000) 1 3204.4 751.5 26.051 2 3303.6 751.5 29.232 3 4573.1 942.0 30.113 _ Mean 3703.7 815.0 28.455 1 Mean thickness was 5.120 mils.
Specimen Stress Strain Modulus at at Number Max. Max. Load Load (psi) (%) (PSIX1000) ' 1 3491.8 941.5 35.107 2 3395.6 941.5 33.745 3 3484.1 942.5 29.576 Mean 3457.1 941.8 32.809 1 Mean thickness mils.
was 4.980 Although illustrated embodimentsof the invention have been described hereinabove, it is to be under-in detail stood that is not ited to those precise the invention lim embodiments, and modifications may and that various changes be readily rdinary skill without effected by persons of o department of the invention and from the spirit or scope being set forth followinglaims. For example, in the c although it preferred is generally that film structures in accordance are coextruded, films with the present invention which are laminated as by sive lamination, heat such adhe and pressure also within the scope or corona lamination are of the present invention.
5/920821.5/SPECFLDR
Claims (14)
1. A multilayer film comprising:
an outer heat-sealable layer comprising an ethylene-based polymer; and a polymeric outer heat-resistant layer having a melting point that is at least 10°F greater than the melting point of the heat-sealable layer, wherein the multilayer film is unperforated, thermoformable and has an oxygen transmission rate greater than 2000 cm 3 mil/m 2-24 hrs atmosphere at 73°F, and wherein all the layers of the film are simultaneously co extruded.
an outer heat-sealable layer comprising an ethylene-based polymer; and a polymeric outer heat-resistant layer having a melting point that is at least 10°F greater than the melting point of the heat-sealable layer, wherein the multilayer film is unperforated, thermoformable and has an oxygen transmission rate greater than 2000 cm 3 mil/m 2-24 hrs atmosphere at 73°F, and wherein all the layers of the film are simultaneously co extruded.
2. The multilayer film according to claim 1, wherein said heat resistant layer comprises a propylene based polymer.
3. The multilayer film according to claim 1, wherein said heat resistant layer comprises a styrene based polymer.
4. The multilayer film according to any one of claims 1 to 3, wherein said heat-sealable layer comprises an ethylene based polymer selected from the group consisting of low density polyethylene, ethylene alpha-olefin copolymers, ethylene vinyl acetate copolymers, ethylene alkyl acrylate copolymers, ethylene acrylic acid copolymers and metal neutralized salts of ethylene acrylic acid and methacyrlic acid copolymers.
5. The multilayer film according to claim 4, wherein said heat-sealable layer comprises a blend of two or more ethylene alpha olefin copolymers of differing densities and viscosities.
6. The multilayer film according to any one of claims 1 to 5, further including at least one internal layer.
7. The multilayer film according to any one of claims 1 to 6 further comprising an internal heat-resistant layer between the outer heat-sealable and outer heat-resistant layers.
8. The multilayer film according to claim 6 or 7, wherein said internal layer comprises a propylene based polymer.
9. The multilayer film according to claim 8, wherein said propylene based polymer is polypropylene.
10. The multilayer film according to claim 8, wherein said propylene based polymer is an ethylene propylene copolymer having a major portion of propylene and a minor portion of ethylene.
11. The multilayer film according to claim 6, wherein said internal layer is a tie layer.
12. The multilayer film according to any one of claims to 1 to 11, wherein the film is formed by laminating the outer sealing layer and the outer heat-resistant layer.
13. A packaging material comprising the multilayer film as defined in any one of claims 1 to 13.
14
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US93642892A | 1992-08-27 | 1992-08-27 | |
| US936,428 | 1992-08-27 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2092968A1 CA2092968A1 (en) | 1994-02-28 |
| CA2092968C true CA2092968C (en) | 2003-03-25 |
Family
ID=25468616
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2092968 Expired - Fee Related CA2092968C (en) | 1992-08-27 | 1993-03-30 | Multi-layered thermoplastic packaging film with improved oxygen permeability |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPH06218865A (en) |
| AU (1) | AU4422693A (en) |
| CA (1) | CA2092968C (en) |
| NO (1) | NO950698L (en) |
| NZ (1) | NZ248250A (en) |
| ZA (1) | ZA935974B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017007996A1 (en) * | 2015-07-08 | 2017-01-12 | The Glad Products Company | Multi-layer thermoplastic films and bags with enhanced odor control and methods of making the same |
| US12049348B2 (en) | 2019-04-10 | 2024-07-30 | Hosokawa Yoko Co., Ltd. | Multilayer film for container and container comprising same |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3266978B2 (en) * | 1993-04-30 | 2002-03-18 | 凸版印刷株式会社 | Package for oxygen scavenger |
| AUPQ466599A0 (en) * | 1999-12-15 | 2000-01-13 | Sporos Sa | Multilayer heat shrinkable film |
| AU2007270031B2 (en) * | 2006-06-29 | 2012-10-25 | Dow Global Technologies Llc | Protective adhesive films |
| JP6500699B2 (en) * | 2015-01-22 | 2019-04-17 | 王子ホールディングス株式会社 | Stretched film |
| US10549888B2 (en) | 2015-07-08 | 2020-02-04 | The Glad Products Company | Thermoplastic films and bags with enhanced odor control and methods of making the same |
| RU2715657C1 (en) * | 2016-07-08 | 2020-03-02 | Констанция Пирк Гмбх Унд Ко. Кг | Recyclable polyethylene film |
| CN106883487A (en) * | 2017-03-15 | 2017-06-23 | 奥克斯空调股份有限公司 | It is a kind of to can be used for the laminated film and its manufacture method of equipment heat-sealing |
-
1993
- 1993-03-30 CA CA 2092968 patent/CA2092968C/en not_active Expired - Fee Related
- 1993-07-26 NZ NZ24825093A patent/NZ248250A/en unknown
- 1993-07-28 AU AU44226/93A patent/AU4422693A/en not_active Abandoned
- 1993-08-16 ZA ZA935974A patent/ZA935974B/en unknown
- 1993-08-26 JP JP5211533A patent/JPH06218865A/en active Pending
-
1995
- 1995-02-24 NO NO950698A patent/NO950698L/en unknown
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017007996A1 (en) * | 2015-07-08 | 2017-01-12 | The Glad Products Company | Multi-layer thermoplastic films and bags with enhanced odor control and methods of making the same |
| US12049348B2 (en) | 2019-04-10 | 2024-07-30 | Hosokawa Yoko Co., Ltd. | Multilayer film for container and container comprising same |
Also Published As
| Publication number | Publication date |
|---|---|
| NO950698L (en) | 1995-04-26 |
| CA2092968A1 (en) | 1994-02-28 |
| ZA935974B (en) | 1994-09-27 |
| JPH06218865A (en) | 1994-08-09 |
| NO950698D0 (en) | 1995-02-24 |
| NZ248250A (en) | 1996-02-27 |
| AU4422693A (en) | 1994-03-03 |
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| EEER | Examination request | ||
| MKLA | Lapsed |