Reinforced thin wall plastic bag, and method and apparatus to make material for such bags

• US 4,076,121 A
• Filed: 02/17/1976
• Issued: 02/28/1978
• Est. Priority Date: 10/15/1973
• Status: Expired due to Term

• Current Assignee: Mobil Oil Corporation (Exxon Mobil Corporation)
• Original Assignee: Mobil Oil Corporation (Exxon Mobil Corporation)
• Inventors: Clayton, William J., Olson, Robert H., Kutniewski, Donald F.
• Primary Examiner(s): Cannon, J.C.
• Application Number:
  US05/658,561
• Time in Patent Office: 742 Days
• Field of Search: 428/167, 428/43, 428/906, 428/182, 229/53, 229/55, 229/3.5 R, 224/177, 206/390, 206/407, 206/824, 206/554, 206/629, 206/819
• US Class Current: 206/390
• CPC Class Codes: B29C 48/0019 combined with shaping by flattening, folding or bending
• CPC Class Codes: B29C 48/08 flexible, e.g. films
• CPC Class Codes: B29C 48/10 flexible, e.g. blown foils
• CPC Class Codes: B29C 48/12 Articles with an irregular circumference when viewed in cross-section, e.g. window profiles
• CPC Class Codes: B29C 48/32 with annular openings, e.g. for forming tubular articles
• CPC Class Codes: B29L 2023/003 having irregular or rough surfaces
• CPC Class Codes: B31B 2155/002 by joining superimposed webs, e.g. with separate bottom webs
• CPC Class Codes: B31B 2155/003 starting from tubular webs
• CPC Class Codes: B31B 70/008 Stiffening or reinforcing B31B70/876 takes precedence
• CPC Class Codes: B65D 33/02 Local reinforcements or stiffening inserts, e.g. wires, strings, strips or frames B65D33/007 takes precedence
• CPC Class Codes: Y10S 206/819 Material
• CPC Class Codes: Y10S 206/824 Tear apertures for roll, strip, or sheet
• CPC Class Codes: Y10S 428/906 Roll or coil
• CPC Class Codes: Y10T 428/15 Sheet, web, or layer weakened to permit separation through thickness
• CPC Class Codes: Y10T 428/2457 Parallel ribs and/or grooves
• CPC Class Codes: Y10T 428/24694 Parallel corrugations

Abstract

A plastic bag such as trash can liners, grass and leaf bags, sandwich bags and the like is reinforced by placing spaced ribs therein, integral with the wall structure, the ribs having a rib-to-rib spacing in the order of 1/8 to 2 cm, the ribs being peaked and merging smoothly from a projecting peak to the thickness of the walls between the ribs, the peaks extending about 1.5 to 10 times the wall thickness of the film which is preferably, in the order of about 0.4 to 2.0 mils. Upon extrusion, the extrusion die is formed with small notches with rounded corners so that the ribs are extruded while the film material is extruded, and provide additional material in the region of the ribs which merges smoothly with the material being extruded to form the film. Such rib-reinforced bag structures may be produced by forming a continuous roll of such bags, the individual bags in such a roll being readily separated along predetermined lines of weakness.

Claims

1. A continuous roll of thermoplastic bags, said bags having been fabricated from a film of low density polyethylene material having a wall thickness on the order of about 0.02 to 0.05 mm and spaced, peaked ribs integral with the film being formed in the film and having a rib-to-rib spacing on the order of 1/8 cm to 2 cm, said ribs merging smoothly from a projecting peak to the thickness of the walls between the ribs, each individual bag being joined in side-by-side relationship by a transversely positioned heat seal line and having a transversely disposed weakened area in the area of said heat seal line whereby removal of a bag from said roll is effected by tearing along said weakened area.

2. A roll of thermoplastic bags in accordance with claim 1, having a weakened area within the confines of said heat seal line.

3. A roll of thermoplastic bags, in accordance with claim 1, having a weakened area extending parallel to and being adjacent to said heat seal line.