US3723222A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for manufacturing corrugated thermoplastic synthetic resin cardboard sheet
Assignee: Mitsui Chemicals Inc
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Filing: 1970-05-01
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Granted: 1973-03-27
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Expires: 1990-05-01
Abstract
Abstract A continuous process for manufacturing with good reproducibility a corrugated thermoplastic synthetic resin cardboard sheet free of defects diminishing the commercial value of the produce such as ''''warp'''' and ''''crookedness''''. This process is characterized in that thin layers of a thermoplastic synthetic resin having a melting point at least 10*C. lower than that of any of thermoplastic synthetic resins constituting the core sheet and surface liner sheets are formed on faces selected from the group consisting of (i) front and back faces of the continuous thermoplastic synthetic resin sheet to be shaped into a core sheet, (ii) faces to be bonded to the core sheet, of each of said surface liners, and (iii) all the faces mentioned in (i) and (ii), before the shaping of the core sheet and before the meltpress bonding of the surface liners onto the continuous core sheet.
Inventors
- 👤 K Kurita
- 👤 H Shigematsu
- 👤 K Yamawaki
- 👤 T Koyama
- 👤 S Endo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 18:42
CPC Classifications
B; B32; B32B; B32B7/00; B32B7/02; B32B7/027; B32B27/00; B32B27/06; B32B27/08; B31; B31F; B31F1/00; B31F1/20; B31F1/24; B31F1/26; B31F1/28; B31F1/2804; B31F1/2809; B32B27/30; B32B27/302; B32B27/304; B32B27/32; B32B3/00; B32B3/26; B32B3/28; B65; B65D; B65D65/00; B65D65/38; B65D65/40; B65D65/403; B32B2323/00; B32B2323/04; B32B2323/043; B32B2323/046; B32B2323/10; Y; Y10; Y10T; Y10T156/00; Y10T156/10; Y10T156/1002; Y10T156/1007; Y10T156/1016; Y10T156/1021; Y10T156/1025
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
23 words
The process of claim 1 wherein said corrugated core sheet and surface liner sheets have a thickness of from 0.05 to 1.0 millimeter.
Claim 2
Dependent Claim
25 words
The process of claim 1 wherein the thickness of the thin layer of copolymer (B) is within a range of from 0.01 to 0.1 millimeter.
Claim 3
Dependent Claim
217 words
A continuous process for the production of a corrugated fiber-free thermoplastic synthetic resin sheet which consists essentially of continuously forwarding a continuous sheet of a thermoplastic synthetic resin (A) selected from the group consisting of polyvinyl chloride, polyvinylidene chloride, polystyrene, low density polyethylene, high density polyethylene, ethylene-propylene copolymer, polypropylene, polybutylene and poly-4-methylpentene-1 to a core sheet shaping zone to shape said sheet of thermoplastic resin (A) into a corrugated core sheet; continuously forwarding surface liner sheets of a thermoplastic resin (A) selected from the group consisting of polyvinyl chloride, polyvinylidene chloride, polystyrene, low density polyethylene, high density polyethylene, ethylene-propylene copolymer, polypropylene, polybutylene and poly-4-methylpentene-1, one surface of each sheet being coated with a thin layer of a copolymer (B) of ethylene and vinyl acetate containing at least 5 percent vinyl acetate, said copolymer (B) having a melting point at least 10*C. lower than thermoplastic resin (A) to a pre-heating zone to soften said thin layers of copolymer (B); simultaneously forwarding said corrugated core sheet and said surface liners to a melt-press bonding zone in a manner so that said surface liners are melt-press bonded to said core sheet with the softened thin layers of copolymer (B) in contact with said corrugated core sheet; and withdrawing said fiber-free corrugated thermoplastic synthetic resin sheet from said melt-press bonding zone.
Claim 4
Dependent Claim
23 words
The process of claim 4 wherein said corrugated core sheet and surface liner sheets have a thickness of from 0.05 to 1.0 millimeter.
Claim 5
Dependent Claim
25 words
The process of claim 4 wherein the thickness of the thin layer of copolymer (B) is within a range of from 0.01 to 0.1 millimeter.
References Cited (Backward Citations)
US2719566A
Cited
US3307994A
Cited
US3518142A
Cited
US3519531A
Cited
US3404748A
Cited
US3617419A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-03-26 | 1976-09-25 | 1977-03-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-26 | 1980-09-25 | 1981-03-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-26 | 1984-09-25 | 1985-03-27 | $7700.00 | Window Closed / Lapsed |