US4668463A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of making linear low density polyethylene film
Assignee: Clopay Plastic Products Co Inc
•
Filing: 1982-07-21
•
Granted: 1987-05-26
•
Expires: 2002-07-21
Abstract
Abstract A method for producing a linear low density polyethylene (LLDPE) film by slot-die extrusion from an extrudate having an inherent draw resonance tendency whereby draw resonance is eliminated in the production of film at high speeds. Film of commercially uniform gauge thickness is obtained having significantly improved strength over films formed by conventional slot-die extrusion of LLDPE.
Inventors
- 👤 Leopoldo V. Cancio
- 👤 James N. Fitzsimmons
- 👤 Robert M. Mortellite
- 👤 Pai-Chuan Wu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 15:33
CPC Classifications
B; B29; B29C; B29C43/00; B29C43/22; B29C43/222; B29C48/00; B29C48/022; B29C48/03; B29C48/07; B29C48/08; B29C48/25; B29C48/88; B29C48/911; B29C48/9135; B29C48/915; B29C48/9155; B29C48/917; B29C55/00; B29C59/00; B29C59/02; B29C59/04; B29K; B29K2023/00; B29K2023/04; B29K2023/06; B29K2023/0608; B29K2023/0625
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
128 words
A method of continuously producing a length of thermoplastic film comprising the steps of: continuously extruding an extrudate comprising linear low density polyethylene having a propensity for draw resonance at high draw speeds when passed through a slot-die in the form of a web, with the extrudate at a temperature above its crystallization temperature, locating a draw roller for the web adjacent the slot of the die to thereby produce a short draw-gap of not more than about six inches, drawing the web into a film having commercially uniform gauge thickness with the draw roller at take-up speeds of at least about several hundred f.p.m., and maintaining the short draw-gap at said speeds whereby said film is continuously formed and draw resonance is substantially eliminated in the web.
Claim 2
Independent Claim
128 words
A method of continuously producing a length of thermoplastic film comprising the steps of: continuously extruding an extrudate comprising linear low density polyethylene having a propensity for draw resonance at high draw speeds when passed through a slot-die in the form of a web, with the extrudate at a temperature above its crystallization temperature, locating a draw roller for the web adjacent the slot of the die to thereby produce a short draw-gap of not more than about six inches, drawing the web into a film having commercially uniform gauge thickness with the draw roller at take-up speeds of at least about several hundred f.p.m., and maintaining the short draw-gap at said speeds whereby said film is continuously formed and draw resonance is substantially eliminated in the web.
Claim 3
Dependent Claim
32 words
The method of claim 1 further including an airknife used in conjunction with the draw roller to form the draw-gap into which the web is introduced to be formed into said film.
Claim 4
Dependent Claim
35 words
The method of claim 2 further including the step of embossing the film with an embossing roller and a rubber roller which cooperate to thereby emboss the surface of the film with a desired texture.
Claim 5
Dependent Claim
28 words
The method of claim 3 wherein the surface of the draw roller is maintained at a temperature that will cause crystallization of the film on the draw roller.
Claim 6
Dependent Claim
26 words
The method of claim 4 wherein the temperature of the draw roller is maintained in the range of from about 230° F. to about 260° F.
Claim 7
Dependent Claim
14 words
The method of claim 3 wherein the draw roller is coated with a polytetrafluoroethylene.
Claim 8
Dependent Claim
12 words
The method of claim 1 wherein the draw-gap is about one inch.
Claim 9
Dependent Claim
20 words
The method of claim 1 wherein the extrudate comprises a blend of linear low density polyethylene and low density polyethylene.
Claim 10
Dependent Claim
23 words
The method of claim 1 wherein the extrudate further comprises a polymer selected from the group of polyethylene, polypropylene and the copolymers thereof.
Claim 11
Dependent Claim
21 words
The method of claim 9 wherein the extrudate is comprised of at least about 30% linear low density polyethylene by weight.
Claim 12
Dependent Claim
14 words
The method of claim 1 wherein the extrudate is 100% linear low density polyethylene.
Claim 13
Independent Claim
168 words
A method for continuously producing a length of thermoplastic film, the thermoplastic film comprised of linear low density polyethylene having a tendency for draw resonance when drawn from a slot-die into a film at high speed, comprising the steps of heating a melt containing linear low density polyethylene to a temperature greater than the crystallization temperature of the linear low density polyethylene, continuously extruding the melt through a slot-die in the form of a web, drawing the web from the slot-die through a nip defined in part by a draw roller whereby the web is drawn into a film, a short draw-gap over which the web is drawn between the nip and the slot of the die being not more than about six inches, and continuously driving the draw roller so as to produce film of a commercially uniform gauge thickness at a rate of at least about several hundred f.p.m., whereby the short draw-gap between the slot-die and the nip substantially eliminates draw resonance in the web.
Claim 14
Independent Claim
168 words
A method for continuously producing a length of thermoplastic film, the thermoplastic film comprised of linear low density polyethylene having a tendency for draw resonance when drawn from a slot-die into a film at high speed, comprising the steps of heating a melt containing linear low density polyethylene to a temperature greater than the crystallization temperature of the linear low density polyethylene, continuously extruding the melt through a slot-die in the form of a web, drawing the web from the slot-die through a nip defined in part by a draw roller whereby the web is drawn into a film, a short draw-gap over which the web is drawn between the nip and the slot of the die being not more than about six inches, and continuously driving the draw roller so as to produce film of a commercially uniform gauge thickness at a rate of at least about several hundred f.p.m., whereby the short draw-gap between the slot-die and the nip substantially eliminates draw resonance in the web.
Claim 15
Dependent Claim
20 words
The method of claim 12 wherein linear low density polyethylene comprises at least about 30% by weight of the extrudate.
Claim 16
Dependent Claim
17 words
The method of claim 13 wherein the film produced has a gauge thickness of approximately 1 mil.
References Cited (Backward Citations)
US2212770A
Cited
US2945261A
Cited
FR1266642A
Cited
US3161560A
Cited
US3277227A
Cited
US3159696A
Cited
US3423493A
Cited
JPS4615706Y1
Cited
US4066729A
Cited
US3964848A
Cited
US4038354A
Cited
US4079114A
Cited
US4129630A
Cited
US4115499A
Cited
US4182606A
Cited
US4336212A
Cited
US4243619A
Cited
US4193961A
Cited
US4211743A
Cited
US4294791A
Cited
US4255365A
Cited
US4230831A
Cited
US4339507A
Cited
US4394474A
Cited
US4486377A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-05-25 | 1990-11-24 | 1991-05-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-05-25 | 1994-11-24 | 1995-05-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-05-25 | 1998-11-24 | 1999-05-26 | $7700.00 | Window Closed / Lapsed |