US4863769A — Puncture resistant, heat-shrinkable films contain…

Claim 1

Independent Claim 102 words

A heat-shrinkable, puncture resistant, biaxially stretched, thermoplastic film suitable for use in fabricating bags for packaging food articles such as frozen poultry, said film comprising a very low density polyethylene which is a linear copolymer of ethylene and higher alpha olefin containing from 3 to 8 carbon atoms having a density below about 0.91 g/cm 3 , a 1% secant modulus below about 140,000 kPa, and said film being formed using a double bubble method and wherein said film heat-shrinks from about 30 percent to about 50 percent at a temperature of about 90° C. in both the machine and transverse directions.

Claim 2

Dependent Claim 102 words

A heat-shrinkable, puncture resistant, biaxially stretched, thermoplastic film suitable for use in fabricating bags for packaging food articles such as frozen poultry, said film comprising a very low density polyethylene which is a linear copolymer of ethylene and higher alpha olefin containing from 3 to 8 carbon atoms having a density below about 0.91 g/cm 3 , a 1% secant modulus below about 140,000 kPa, and said film being formed using a double bubble method and wherein said film heat-shrinks from about 30 percent to about 50 percent at a temperature of about 90° C. in both the machine and transverse directions.

Claim 3

Dependent Claim 24 words

A film as in claim 1 wherein said alpha olefins are selected from the group consisting of propylene, butene-1, pentene-1,4-methylpentene-1, hexene-1, heptene-1 and octene-1.

Claim 4

Dependent Claim 39 words

A film as in claim 1 wherein the polyethylene copolymer has a density of from about 0.86 g./cm. 3 to about 0.91 g./cm. 3 , and a 1% secant modulus of from about 600 kPa to about 100,000 kPa.

Claim 5

Dependent Claim 23 words

A film as in claim 1 wherein the polyethylene copolymer has a standard load melt index of up to about 25.0 g./10 minutes.

Claim 6

Dependent Claim 22 words

A film as in claim 1 wherein polyethylene copolymer has a high load melt index of up to about 1000 g./10 minutes.

Claim 7

Dependent Claim 13 words

A film as in claim 1 wherein said film comprises a monolayer film.

Claim 8

Dependent Claim 20 words

A film as in claim 1 wherein the very low density polyethylene copolymer is blended with an ethylene-vinyl acetate copolymer.

Claim 9

Dependent Claim 13 words

A film as in claim 1 wherein said film comprises a multilayer film.

Claim 10

Dependent Claim 21 words

A film as in claim 1 wherein said film has a thickness of from about 1.5 mils to about 2.75 mils.

Claim 11

Dependent Claim 25 words

A film as in claim 1 wherein said film has been irradiated to a dosage level of between about 1 megarad and about 5 megarads.

Claim 12

Dependent Claim 13 words

A film as in claim 1 fabricated in the form of a bag.

Claim 13

Dependent Claim 14 words

A multilayer film as in claim 8 wherein said film is prepared by coextrusion.

Claim 14

Dependent Claim 111 words

A heat-shrinkable, biaxially stretched, multilayer thermoplastic film suitable for use in fabricating bags for packaging food articles wherein at least one layer of said multilayer film comprises a blend of very low density polyethylene which is a linear copolymer of ethylene and higher alpha olefin containing from 3 to 8 carbon atoms having a density below about 0.91 g/cm 3 and a 1% secant modulus below about 140,000 kPa, and an ethylene-vinyl acetate copolymer, said multilayer film being formed using a double bubble method and wherein said film heat-shrinks from about 30 percent to about 50 percent at a temperature of about 90° C. in both the machine and transverse directions.

Claim 15

Dependent Claim 111 words

A heat-shrinkable, biaxially stretched, multilayer thermoplastic film suitable for use in fabricating bags for packaging food articles wherein at least one layer of said multilayer film comprises a blend of very low density polyethylene which is a linear copolymer of ethylene and higher alpha olefin containing from 3 to 8 carbon atoms having a density below about 0.91 g/cm 3 and a 1% secant modulus below about 140,000 kPa, and an ethylene-vinyl acetate copolymer, said multilayer film being formed using a double bubble method and wherein said film heat-shrinks from about 30 percent to about 50 percent at a temperature of about 90° C. in both the machine and transverse directions.

Claim 16

Dependent Claim 34 words

A film as in claim 13 wherein said blend comprises from about 5 weight percent to about 25 weight percent of said very low density polyethylene copolymer, based on the weight of said blend.

Claim 17

Dependent Claim 130 words

A heat-shrinkable, biaxially stretched, multilayer thermoplastic film suitable for use in fabricating bags for packaging primal meat cut and processed meat products; said film comprising a first outer layer of an ethylene-vinyl acetate copolymer; a core layer comprising a barrier film; and a second outer layer comprising a blend of an ethylene-vinyl acetate copolymer and a very low density polyethylene which is a linear copolymer of ethylene and higher alpha olefin containing from 3 to 8 carbon atoms having a density below about 0.91 g/cm, a 1% secant modulus below about 140,000 kPa, and said film being formed using a double bubble method and wherein said film heat-shrinks from about 30 percent to about 50 percent at a temperature of about 90° C. in both the machine and transverse directions.

Claim 18

Dependent Claim 130 words

A heat-shrinkable, biaxially stretched, multilayer thermoplastic film suitable for use in fabricating bags for packaging primal meat cut and processed meat products; said film comprising a first outer layer of an ethylene-vinyl acetate copolymer; a core layer comprising a barrier film; and a second outer layer comprising a blend of an ethylene-vinyl acetate copolymer and a very low density polyethylene which is a linear copolymer of ethylene and higher alpha olefin containing from 3 to 8 carbon atoms having a density below about 0.91 g/cm, a 1% secant modulus below about 140,000 kPa, and said film being formed using a double bubble method and wherein said film heat-shrinks from about 30 percent to about 50 percent at a temperature of about 90° C. in both the machine and transverse directions.

Claim 19

Dependent Claim 26 words

A film as in claim 15 wherein said barrier film is selected from the group consisting of a polyvinylidene chloride copolymer, and an ethylene-vinyl alcohol copolymer.

Claim 20

Dependent Claim 34 words

A film as in claim 15 wherein said blend comprises from about 5 weight percent to about 25 weight percent of the very low density polyethylene copolymer, based on the weight of said blend.

Claim 21

Dependent Claim 24 words

A film as in claim 15 wherein said alpha olefins are selected from the group consisting of propylene, butene-1, pentene-1,4-methylpentene-1, hexene-1, heptene-1 and octene-1.

Claim 22

Dependent Claim 39 words

A film as in claim 15 wherein the polyethylene copolymer has a density of from about 0.86 g./cm. 3 to about 0.91 g./cm. 3 , and a 1% secant modulus of from about 600 kPa to about 100,000 kPa.

Claim 23

Dependent Claim 22 words

A film as in claim 15 wherein polyethylene copolymer has a standard load melt index of up to about 25.0 g./10 minutes.

Claim 24

Dependent Claim 23 words

A film as in claim 15 wherein the polyethylene copolymer has a high load melt index of up to about 1000 g./10 minutes.

Claim 25

Dependent Claim 21 words

A film as in claim 15 wherein said film has a thickness of from about 1.75 mils to about 3.0 mils.

Claim 26

Dependent Claim 25 words

A film as in claim 15 wherein said film has been irradiated to a dosage level of between about 1 megarad and about 5 megarads.

Claim 27

Dependent Claim 13 words

A film as in claim 15 fabricated in the form of a bag.

Claim 28

Dependent Claim 107 words

A film as in claim 15 wherein said ethylene-vinyl acetate copolymer in said second outer layer comprises a blend of two ethylene-vinyl acetate copolymers wherein one of said ethylene-vinyl acetate copolymers has a melt index of from about 0.1 to about 1.0 decigram per minute and a vinyl acetate content of from about 10 to about 18 weight percent, based on the weight of said copolymer, and the other ethylene-vinyl acetate copolymer has a melt index of from about 0.1 to about 1.0 decigram per minute and a vinyl acetate content of from about 2 to about 10 weight percent, based on the weight of said copolymers.

Claim 29

Dependent Claim 13 words

A film as in claim 25 fabricated in the form of a bag.

Claim 30

Dependent Claim 40 words

A film as in claim 25 wherein said blend of ethylene-vinyl acetate copolymers has a vinyl acetate content of from about 3 weight percent to about 18 weight percent, based on the weight of said blend of ethylene-vinyl acetate copolymers.

Claim 31

Dependent Claim 39 words

A film as in claim 15 wherein said first outer layer comprises an ethylene-vinyl acetate copolymer having a vinyl acetate content of from about 9 weight percent to about 15 weight percent, based on the weight of said copolymer.

Claim 32

Dependent Claim 27 words

The film of claim 15 wherein said barrier layer comprises a copolymer of vinylidene chloride and said second outer layer is directly bonded to said barrier layer.

Claim 33

Dependent Claim 121 words

A heat-shrinkable, puncture-resistant, biaxially stretched, thermoplastic film suitable for use in fabricating bags for packaging food articles such as frozen poultry, said film comprising a very low density polyethylene which is a linear copolymer of ethylene and higher alpha olefin containing from 3 to 8 carbon atoms having a density below 0.91 g/cm 3 , a 1% secant modulus below about 140,000 kPa, the polyethylene copolymer comprising ethylene copolymerized with a higher alpha-olefin in the presence of a catalyst comprising magnesium and titanium, and said film being formed using a double bubble method and having a heat shrinkage of from about 30 percent to about 50 percent at a temperature of about 90° C. in both the machine and transverse directions.

Claim 34

Dependent Claim 121 words

A heat-shrinkable, puncture-resistant, biaxially stretched, thermoplastic film suitable for use in fabricating bags for packaging food articles such as frozen poultry, said film comprising a very low density polyethylene which is a linear copolymer of ethylene and higher alpha olefin containing from 3 to 8 carbon atoms having a density below 0.91 g/cm 3 , a 1% secant modulus below about 140,000 kPa, the polyethylene copolymer comprising ethylene copolymerized with a higher alpha-olefin in the presence of a catalyst comprising magnesium and titanium, and said film being formed using a double bubble method and having a heat shrinkage of from about 30 percent to about 50 percent at a temperature of about 90° C. in both the machine and transverse directions.

Claim 35

Dependent Claim 154 words

A heat-shrinkable, biaxially stretched, multilayer thermoplastic film suitable for use in fabricating bags for packaging primal meat cuts and processed meat products; said film comprising a first outer layer of an ethylene-vinyl acetate copolymer, a core layer comprising a barrier film; and a second outer layer comprising a blend of an ethylene-vinyl acetate copolymer and a very low density polyethylene which is a linear copolymer of ethylene and higher alpha olefin containing from 3 to 8 carbon atoms having a density of below about 0.91 g/cm 3 , a 1% secant modulus below about 140,000 kPa, the polyethylene copolymer comprising ethylene copolymerized with a higher alpha-olefin in the presence of a catalyst comprising magnesium and titanium; and said film being formed using a double bubble method and having a heat shrinkage of from about 30 percent to about 50 percent at a temperature of about 90° C. in both the machine and transverse directions.

Claim 36

Dependent Claim 154 words

A heat-shrinkable, biaxially stretched, multilayer thermoplastic film suitable for use in fabricating bags for packaging primal meat cuts and processed meat products; said film comprising a first outer layer of an ethylene-vinyl acetate copolymer, a core layer comprising a barrier film; and a second outer layer comprising a blend of an ethylene-vinyl acetate copolymer and a very low density polyethylene which is a linear copolymer of ethylene and higher alpha olefin containing from 3 to 8 carbon atoms having a density of below about 0.91 g/cm 3 , a 1% secant modulus below about 140,000 kPa, the polyethylene copolymer comprising ethylene copolymerized with a higher alpha-olefin in the presence of a catalyst comprising magnesium and titanium; and said film being formed using a double bubble method and having a heat shrinkage of from about 30 percent to about 50 percent at a temperature of about 90° C. in both the machine and transverse directions.

Claim 37

Dependent Claim 101 words

A heat-shrinkable, biaxially stretched, monolayer thermoplastic film suitable for use in fabricating bags for packaging food articles wherein said film comprises very low density polyethylene which is a linear copolymer of ethylene and higher alpha olefin containing from 3 to 8 carbon atoms, having a density below about 0.91 g/cm 3 and a 1% secant modulus of from about 600 kPa to about 100,000 kPa, said film being formed using a double bubble method and wherein said film heat-shrinks from about 30 percent to about 50 percent at a temperature of about 90° C. in both the machine and transverse directions.

Claim 38

Dependent Claim 101 words

A heat-shrinkable, biaxially stretched, monolayer thermoplastic film suitable for use in fabricating bags for packaging food articles wherein said film comprises very low density polyethylene which is a linear copolymer of ethylene and higher alpha olefin containing from 3 to 8 carbon atoms, having a density below about 0.91 g/cm 3 and a 1% secant modulus of from about 600 kPa to about 100,000 kPa, said film being formed using a double bubble method and wherein said film heat-shrinks from about 30 percent to about 50 percent at a temperature of about 90° C. in both the machine and transverse directions.

Claim 39

Dependent Claim 99 words

A heat-shrinkable, puncture resistant, biaxially stretched, thermoplastic film suitable for use in fabricating bags for packaging food articles such as frozen poultry, said film comprising a very low density polyethylene which is a linear copolymer of ethylene and higher alpha olefin containing from 3 to 8 carbon atoms, having a density below about 0.91 g/cm 3 , a 1% secant modulus below about 140,000 kPa, and said film being formed using a double bubble method and wherein said film heat-shrinks from about 30 percent to about 50 percent at a temperature of about 90° C. in the transverse direction.

Claim 40

Dependent Claim 99 words

A heat-shrinkable, puncture resistant, biaxially stretched, thermoplastic film suitable for use in fabricating bags for packaging food articles such as frozen poultry, said film comprising a very low density polyethylene which is a linear copolymer of ethylene and higher alpha olefin containing from 3 to 8 carbon atoms, having a density below about 0.91 g/cm 3 , a 1% secant modulus below about 140,000 kPa, and said film being formed using a double bubble method and wherein said film heat-shrinks from about 30 percent to about 50 percent at a temperature of about 90° C. in the transverse direction.

Claim 41

Dependent Claim 99 words

A heat-shrinkable, puncture resistant, biaxially stretched, thermoplastic film suitable for use in fabricating bags for packaging food articles such as frozen poultry, said film comprising a very low density polyethylene which is a linear copolymer of ethylene and higher alpha olefin containing from 3 to 8 carbon atoms, having a density below about 0.91 g/cm 3 , a 1% secant modulus below about 140,000 kPa, and said film being formed using a double bubble method and wherein said film heat-shrinks from about 30 percent to about 50 percent at a temperature of about 90° C. in the machine direction.

Claim 42

Dependent Claim 99 words

A heat-shrinkable, puncture resistant, biaxially stretched, thermoplastic film suitable for use in fabricating bags for packaging food articles such as frozen poultry, said film comprising a very low density polyethylene which is a linear copolymer of ethylene and higher alpha olefin containing from 3 to 8 carbon atoms, having a density below about 0.91 g/cm 3 , a 1% secant modulus below about 140,000 kPa, and said film being formed using a double bubble method and wherein said film heat-shrinks from about 30 percent to about 50 percent at a temperature of about 90° C. in the machine direction.

Claim 43

Dependent Claim 97 words

A heat-shrinkable, puncture resistant, biaxially stretched, thermoplastic film suitable for use in fabricating bags for packaging food articles such as frozen poultry, said film comprising a very low density polyethylene which is a linear copolymer of ethylene and higher alpha olefin containing from 3 to 8 carbon atoms, having a density below about 0.91 g/cm 3 , a 1% secant modulus below about 140,000 kPa, and said film being formed using a double bubble method and wherein said film heat-shrinks from 52 percent to 54 percent at a temperature of about 90° C. in the transverse direction.

Claim 44

Dependent Claim 97 words

A heat-shrinkable, puncture resistant, biaxially stretched, thermoplastic film suitable for use in fabricating bags for packaging food articles such as frozen poultry, said film comprising a very low density polyethylene which is a linear copolymer of ethylene and higher alpha olefin containing from 3 to 8 carbon atoms, having a density below about 0.91 g/cm 3 , a 1% secant modulus below about 140,000 kPa, and said film being formed using a double bubble method and wherein said film heat-shrinks from 52 percent to 54 percent at a temperature of about 90° C. in the transverse direction.

Claim 45

Dependent Claim 97 words

A heat-shrinkable, puncture resistant, biaxially stretched, thermoplastic film suitable for use in fabricating bags for packaging food articles such as frozen poultry, said film comprising a very low density polyethylene which is a linear copolymer of ethylene and higher alpha olefin containing from 3 to 8 carbon atoms, having a density below about 0.91 g/cm 3 , a 1% secant modulus below about 140,000 kPa, and said film being formed using a double bubble method and wherein said film heat-shrinks from 51 percent to 52 percent at a temperature of about 90° C. in the machine direction.

Claim 46

Dependent Claim 97 words

A heat-shrinkable, puncture resistant, biaxially stretched, thermoplastic film suitable for use in fabricating bags for packaging food articles such as frozen poultry, said film comprising a very low density polyethylene which is a linear copolymer of ethylene and higher alpha olefin containing from 3 to 8 carbon atoms, having a density below about 0.91 g/cm 3 , a 1% secant modulus below about 140,000 kPa, and said film being formed using a double bubble method and wherein said film heat-shrinks from 51 percent to 52 percent at a temperature of about 90° C. in the machine direction.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1992-09-04	1993-03-06	1993-09-05	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1996-09-04	1997-03-06	1997-09-05	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2000-09-04	2001-03-06	2001-09-05	$7700.00	Window Closed / Lapsed

Puncture resistant, heat-shrinkable films containing very low density polyethylene

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