Patent US5091237A successfully refreshed from Google Patents.
US5091237A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Transparent shrink film based on polypropylene, process for its manufacture, and its use for shrink labels
Assignee: Hoechst AG
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Filing: 1989-06-26
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Granted: 1992-02-25
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Expires: 2009-06-26
Abstract
Abstract A shrink film comprising at least one polyolefinic layer comprising polypropylene and a resin admixture is disclosed. The film processes a shrinkability of more than 20%, measured at 90° C., in the transverse direction and of less than 8%, also measured at 90° C., in the longitudinal direction. The film is manufactured by coextrusion followed by stretching in the longitudinal and transverse directions, whereby stretching in the longitudinal direction is performed such that the birefringence value Δn of the longitudinally oriented film does not exceed the range from 10×10 -3 to 13×10 -3 .
Inventors
- 👤 Gunter Schloegl
- 👤 Lothar Bothe
- 👤 Guenther Crass
- 👤 Ursula Murschall
- 👤 Herbert Peiffer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 21:46
CPC Classifications
B; B29; B29C; B29C55/00; B29C55/02; B29C55/10; B29C55/12; B29C55/14; B29C55/143; B32; B32B; B32B27/00; B32B27/06; B32B27/08; B32B27/18; B32B27/32; B29K; B29K2023/00; B29K2023/10; B29K2023/12; B29K2995/00; B29K2995/0037; B29K2995/0049; B32B2307/00; B32B2307/40; B32B2307/412; B32B2307/50; B32B2307/51; B32B2307/54; B32B2307/70; B32B2307/732; B32B2307/734; B32B2307/736; B32B2323/00; B32B2323/10; Y; Y10; Y10S; Y10S428/00; Y10S428/91; Y10T; Y10T428/00; Y10T428/24; Y10T428/24942; Y10T428/2495; Y10T428/24967; Y10T428/28; Y10T428/2813; Y10T428/2817; Y10T428/2826; Y10T428/31504; Y10T428/31855; Y10T428/31909; Y10T428/31913; Y10T428/31924
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
159 words
Transparent shrinkable film comprising: a base layer comprising a mixture of about 60 to 95% by weight of a propylene polymer and about 5 to 40% by weight of a hydrogenated hydrocarbon resin having a softening point in the range from 60° to 125° C., the percentages being related to the total weight of the mixture employed for the base layer, and a top layer on each of the two surfaces of said base layer comprising a propylene polymer and a hydrogenated hydrocarbon resin having a softening point in the range of 90° to 145° C., said top layers comprising about 60 to 100% by weight of the propylene polymer and up to 40% by weight of the hydrogenated hydrocarbon resin, the percentages being related to the total weight of the top layers, said film being a shrinkable film which is stretched in the longitudinal and transverse directions and has a low degree of orientation in the longitudinal direction.
Claim 2
Dependent Claim
159 words
Transparent shrinkable film comprising: a base layer comprising a mixture of about 60 to 95% by weight of a propylene polymer and about 5 to 40% by weight of a hydrogenated hydrocarbon resin having a softening point in the range from 60° to 125° C., the percentages being related to the total weight of the mixture employed for the base layer, and a top layer on each of the two surfaces of said base layer comprising a propylene polymer and a hydrogenated hydrocarbon resin having a softening point in the range of 90° to 145° C., said top layers comprising about 60 to 100% by weight of the propylene polymer and up to 40% by weight of the hydrogenated hydrocarbon resin, the percentages being related to the total weight of the top layers, said film being a shrinkable film which is stretched in the longitudinal and transverse directions and has a low degree of orientation in the longitudinal direction.
Claim 3
Dependent Claim
53 words
Film as claimed in claim 1, wherein the propylene polymer of the base layer comprises an isotactic polypropylene with an n-heptane-soluble fraction of 10% by weight or less and having a melt flow index of about 0.5 g/10 min to 8 g/10 min, at 230° C. and under a load of 2.16 kg.
Claim 4
Dependent Claim
46 words
Film as claimed in claim 1, wherein the propylene polymer of the top layers comprises an isotactic polypropylene with an n-heptane-soluble fraction of 10% by weight or less and having a melt flow index in the range of about 5 g/10 min. to 20 g/10 min.
Claim 5
Dependent Claim
32 words
Film as claimed in claim 1, wherein the hydrogenated hydrocarbon resin in said base layer is a low-molecular-weight synthetic resin having a softening point in the range of 70° to 90° C.
Claim 6
Dependent Claim
16 words
Film as claimed in claim 4, wherein the hydrogenated hydrocarbon resin comprises a hydrogenated cyclopentadiene resin.
Claim 7
Dependent Claim
18 words
Film as claimed in claim 1, wherein the top layers additionally comprise an inorganic or organic slip agent.
Claim 8
Dependent Claim
50 words
Film as claimed in claim 6, wherein the slip agent comprises silicon dioxide or calcium carbonate having a mean particle size of between 1.5 and 3 μm and an aspect ratio in the range of 1 to 4.5, that is present in an amount of 0.1 to 0.5% by weight.
Claim 9
Dependent Claim
25 words
Film as claimed in claim 1, having a thickness of about 15 to 50 μm, with the top layers being 0.5 to 1.0 μm thick.
Claim 10
Dependent Claim
15 words
Film as claimed in claim 8, having a thickness of about 20 to 45 μm.
Claim 11
Dependent Claim
72 words
Film as claimed in claim 1, having a shrinkability in the transverse direction of more than about 20% at 90° C. and of more than about 40% of 120° C., and a shrinkability in the longitudinal direction of less than about 8% at 90° C. and of less than about 16% at 120° C., the percentages being in each case related to the dimensions of the film prior to the shrink process.
Claim 12
Dependent Claim
76 words
Film as claimed in claim 10, having a shrinkability in the transverse direction of about 20% to 30% at 90° C. and of about 40% to 60% at 120° C., and a shrinkability in the longitudinal direction of not more than 4% to 8% at 90° C. and of not more than 10% to 16% at 120° C., the percentages being in each case related to the dimensions of the film prior to the shrink process.
Claim 13
Dependent Claim
40 words
Film as claimed in claim 1, having a modulus of elasticity in the longitudinal direction of more than about 2,000 N/mm 2 , and a modulus of elasticity in the transverse direction of more than about 4,000 N/mm 2 .
Claim 14
Dependent Claim
41 words
Film as claimed in claim 12, having a modulus of elasticity in the longitudinal direction of about 2,200 to 2,600 N/mm 2 and a modulus of elasticity in the transverse direction of about 4,500 N/mm 2 to 5,500 N/mm 2 .
Claim 15
Dependent Claim
38 words
Film as claimed in claim 1, having a tear resistance in the longitudinal direction of more than about 130 N/mm 2 , and a tear resistance in the transverse direction of more than about 220 N/mm 2 .
Claim 16
Dependent Claim
37 words
Film as claimed in claim 4, having a tear resistance in the longitudinal direction of about 145 to 185 N/mm 2 and a tear resistance in the transverse direction of about 235 to 290 N/mm 2 .
Claim 17
Dependent Claim
189 words
Process for the manufacture of a transparent shrinkable film as claimed in claim 1, comprising the steps of: first producing a prefilm comprising a base layer that is a mixture of about 60 to 95% by weight of a propylene polymer and about 5 to 40% by weight of a hydrogenated hydrocarbon resin having a softening point in the range from 60° to 125° C., the percentages being related to the total weight of the mixture employed for the base layer, and a top layer on each of the two surfaces of said base layer, said top layers comprising about 60 to 100% by weight of a propylene polymer and about 0 to 40% by weight of a hydrogenated hydrocarbon resin having a softening point in the range of 90° to 145° C., the percentages being related to the total weight of the top layers; and subsequently orienting the resulting film by stretching it in the longitudinal and in the transverse directions, during which the conditions for the longitudinal stretching are set such that the degree of orientation of the film stretched only in the longitudinal direction is low.
Claim 18
Dependent Claim
32 words
Film as claimed in claim 1, wherein the hydrogenated hydrocarbon resin in said top layers is a low-molecular-weight synthetic resin having a softening point in the range of 110° to 135° C.
Claim 19
Dependent Claim
31 words
Film as claimed in claim 4, wherein the hydrogenated resin in said top layers is a low-molecular-weight synthetic resin having a softening point in the range of 110° to 135° C.
Claim 20
Dependent Claim
53 words
Film as claimed in claim 18, wherein the propylene polymer of the base layer comprises an isotactic polypropylene with an n-heptane-soluble fraction of 10% by weight or less and having a melt flow index of about 1.5 g/10 min to 4 g/10 min, at 230° C. and under a load of 2.16 kg.
Claim 21
Dependent Claim
21 words
Film as claimed in claim 19, wherein the hydrogenated resin is a cyclopentadiene resin having a saybolt number greater than 20.
Claim 22
Dependent Claim
34 words
Film as claimed in claim 1, wherein the top layer comprises at least about 0.5% by weight of the hydrogenated hydrocarbon resin having a softening point in the range of 90° to 145° C.
Claim 23
Dependent Claim
77 words
Process for the manufacture of a film as claimed in claim 16, comprising the steps of: first producing a prefilm by coextrusion through a slot die; solidifying said prefilm on a chilling roll, and subsequently orienting the resulting film by stretching it in the longitudinal and in the transverse directions, during which the conditions for the longitudinal stretching are set such that the degree of orientation of the film stretched only in the longitudinal direction is low.
Claim 24
Dependent Claim
38 words
Process as claimed in claim 22, wherein the birefringence of the film stretched in the longitudinal direction, but not yet stretched in the transverse direction does not exceed a value Δn of 10×10 -3 to 13×10 -3 .
Claim 25
Dependent Claim
58 words
Process as claimed in claim 22, wherein stretching in the longitudinal direction is performed at a temperature about 140° C., at a stretching ratio of less than 4.5, and wherein stretching in the transverse direction is performed at a temperature below about 120° C., and at a stretching ratio in the transverse direction of more than about 8.
Claim 26
Dependent Claim
48 words
Process as claimed in claim 22, wherein stretching of the film in the transverse direction is followed by a final setting step, during which the film is conveyed on in the tenter frame, at a temperature that is about 20° C. to 40° C. below the stretching temperature.
Claim 27
Dependent Claim
64 words
Process as claimed in claim 24, wherein stretching in the longitudinal direction is performed at a temperature in the range of about 145° to 155° C. and at a stretching ratio of about 3 to 4, and wherein stretching in the transverse direction is performed at a temperature below about 110° C. and at a stretching ratio in the range of 8.5 to 11.
Claim 28
Dependent Claim
19 words
Process as claimed in claim 25, wherein the temperature during the final setting step is below about 110° C.
Claim 29
Dependent Claim
19 words
Process as claimed in claim 27, wherein the temperature during the final setting step is below about 80° C.
Claim 30
Dependent Claim
20 words
Process as claimed in claim 25, wherein the film is conveyed on the tenter frame in a slightly converging manner.
Claim 31
Dependent Claim
22 words
Process as claimed in claim 29, wherein the convergence during the setting step is in the range of about 5 to 15%.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-02-24 | 1995-08-26 | 1996-02-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-02-24 | 1999-08-26 | 2000-02-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-02-24 | 2003-08-26 | 2004-02-25 | $7700.00 | Window Closed / Lapsed |