US3799042A - Flat-bottom plastic bags and method for the production thereof - Google Patents

Flat-bottom plastic bags and method for the production thereof Download PDF

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Publication number
US3799042A
US3799042A US00243946A US24394672A US3799042A US 3799042 A US3799042 A US 3799042A US 00243946 A US00243946 A US 00243946A US 24394672 A US24394672 A US 24394672A US 3799042 A US3799042 A US 3799042A
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US
United States
Prior art keywords
bag
gusset
folded
edge
folding
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00243946A
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English (en)
Inventor
G Platz
J Honn
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Millennium Petrochemicals Inc
Original Assignee
National Destillers and Chemical Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by National Destillers and Chemical Corp filed Critical National Destillers and Chemical Corp
Priority to US00243946A priority Critical patent/US3799042A/en
Priority to BE129916A priority patent/BE798095A/xx
Priority to NL7305201A priority patent/NL7305201A/xx
Priority to FR7313441A priority patent/FR2180402A5/fr
Priority to IT23006/73A priority patent/IT982766B/it
Priority to SE7305323A priority patent/SE7305323L/xx
Priority to JP48041493A priority patent/JPS4919976A/ja
Priority to LU67422A priority patent/LU67422A1/xx
Priority to US413467A priority patent/US3917159A/en
Application granted granted Critical
Publication of US3799042A publication Critical patent/US3799042A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D31/00—Bags or like containers made of paper and having structural provision for thickness of contents
    • B65D31/10—Bags or like containers made of paper and having structural provision for thickness of contents with gusseted sides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B31—MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER; WORKING PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31B—MAKING CONTAINERS OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31B70/00—Making flexible containers, e.g. envelopes or bags
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B31—MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER; WORKING PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31B—MAKING CONTAINERS OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31B2155/00—Flexible containers made from webs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B31—MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER; WORKING PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31B—MAKING CONTAINERS OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31B2155/00—Flexible containers made from webs
    • B31B2155/001—Flexible containers made from webs by folding webs longitudinally
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B31—MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER; WORKING PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31B—MAKING CONTAINERS OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31B2155/00—Flexible containers made from webs
    • B31B2155/001—Flexible containers made from webs by folding webs longitudinally
    • B31B2155/0014—Flexible containers made from webs by folding webs longitudinally having their openings facing transversally to the direction of movement
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B31—MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER; WORKING PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31B—MAKING CONTAINERS OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31B2155/00—Flexible containers made from webs
    • B31B2155/003—Flexible containers made from webs starting from tubular webs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B31—MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER; WORKING PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31B—MAKING CONTAINERS OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31B2160/00—Shape of flexible containers
    • B31B2160/20—Shape of flexible containers with structural provision for thickness of contents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B31—MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER; WORKING PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31B—MAKING CONTAINERS OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31B2170/00—Construction of flexible containers
    • B31B2170/30—Construction of flexible containers having corrugated or pleated walls

Definitions

  • ABSTRACT A flat-bottom plastic bag produced from an extruded length of gusseted and thermoplastic material including the steps of sealing and severing a length of such material to provide a closed bottom; folding the upper portion of each gusset inwardly toward the center of the bag to create triangular portions at the bottom of each gusset, the bottom corners of the bag tapering inwardly with the taper being determined by the outer leg of each triangular portion; opening the folded gusset portions to a flattened position, each triangular portion being folded simultaneously along a median line and the inwardly tapered bottom configuration of the bag being retained; folding the tapered bottom portion of the bag upwardly toward the front of the bag thereby creating a transverse fold line extending from edge to edge of the bag, the height of this folded portion being substantially identical to the height of the folded medianline of each triangular portion, the height of
  • This invention relates to a method for manufacturing a novel bag produced from thermoplastic material having inherent heat-sealable characteristics, such as polyethylene, polypropylene, and the like, and to the bag produced by this method.
  • the bags must include a substantially rectangular and flat-bottom surface and the gauge or thickness of the thermoplastic sheet material employed must be such that the bag walls will be self-sustaining; thus, the bag will stand erect, resting securely upon its flat bottom, when in opened position and filled or partially filled.
  • Bags of the character with which we here are concerned are commercially available to a degree; however, problems inherent to known methods of manufacture (particular reference is had to the folding of the bag so that it will open readily and stand upon its flat bottom when filled or partially filled) have added materially to the costs. It is a major object of the present invention to provide a novel method of manufacture and folding whereby such bags can be produced with greater economy than has been known heretofore.
  • a still further object of the invention is the production of a bag of the character with which we here are concerned from a continuous length or tube of heatsealable thermoplastic material which has been extruded and flattened to provide a gusset at each side thereof, external transverse sealing and severance or perforation between adjacent bags being accomplished after the formation of such gussets.
  • FIG. 1 is a fragmentary perspective view of the bottom portion of a flat bottom plastic bag produced in accordance with the present invention
  • FIG. 2 is a transverse sectional view, on an enlarged scale, taken on the line 2-2 of FIG. 1;
  • FIG. 3 is a plan view of a length of gusseted, thermoplastic tubular material, sealed along the bottom edge thereof and illustrating the initial step of the novel method of the present invention
  • FIG. 4 is a transverse sectional view, on an enlarged scale, taken on the line 44 of FIG. 3.
  • FIG. 5 is a fragmentary sectional view of the lower extremity of the bag, illustrating the second step of the present method, the open portion of each gusset having been folded inwardly toward the center of the bag;
  • FIG. 6 is a detail transverse section view, on an enlarged scale, taken on the line 66 of FIG. 5;
  • FIG. 7 is a fragmentary plan view, similar to FIG. 5 and illustrating the third step of the method, the folded gusset portions having been opened outwardly and returned to the original positions thereof;
  • FIG. 8 is a transverse detail sectional view on an enlarged scale taken on the line 8-8 of FIG. 7;
  • FIG. 9 is a plan view of the lower extremity of the bag, similar to FIGS. 5 and 7, illustrating the fourth step of the present method, the closed bottom of the bag having been folded upwardly to a plane immediately above that of the remainder of the bag;
  • FIG. 10 is a detail vertical sectional view on an enlarged scale taken on the line l0-l0 of FIG. 9;
  • FIG. 11 is a plan view similar to FIG. 9, illustrating the final step of the present method, the upwardly folded bottom portion of the bag having been returned to a plane contiguous to that of the bag proper.
  • the tube 10 of the present invention has been heat-sealed transversely along the bottom edge and severed, forming a length of seamless thermoplastic tubing produced by an extrusion process and flattened as is well-known in this art.
  • the severed bag in- cludes a front wall 11 and a rear wall 12 united along the longitudinal thereof by gussets l3 and 16 as is well known in this art.
  • Gusset 13 is constituted by an upper portion 14 and a lower portion 15; similarly, the opposed gusset 16 is constituted by an upper portion 17 and a lower portion 18.
  • thermoplastic material or tube is heat-sealed transversely from edge to edge thereof, as indicated at 19, and then severed, thereby providing a bottom closure for the initial bag and an open mouth edge for the next adjacent bag, the invention contemplating the successive production of bags from a continuous length of tubing.
  • transverse seal 19 securely unites or welds the bottom edges of the front and rear walls of panels 11 and 12 to each other and that this seal also includes the gusseted portions 13 and 16.
  • thermoplastic material constituting the front and rear walls of the bag; however, in the outer portions of the seal 19 there are four layers of thermoplastic material, constituted by the two opposed layers 14 and 15 of the gusset 13 and the comparable layers 17 and 18 of the gusset 16 which are heat-sealed between the front and rear walls 11 and 12.
  • each edge gusset is folded reversely toward the center of the bag, to the position illustrated in FIG. 5 of the drawings.
  • This folding operation creates a double-walled triangular portion 20 along the lower extremity of the gusset 13 and a companion double-walled triangular portion 21 along the lower extremity of the gusset 16.
  • the lower wall of each of the triangular portions 20 and 21 is constituted by the tubular material on both sides of the opposed extremities of the sealed bottom portion; the upper wall of each triangular portion is contiguous with the lower wall thereof and is constituted by the immediately adjacent portion of the associated gusset.
  • the vertical center line of the outer surface or wall of each of these triangular portions is constituted by an extremity of the sealed bottom edge 19 and the bottom corners of the bag are inwardly tapered as indicated by the outer folded edge 22 of the gusset triangle 20 and the outer folded edge 23 of the triangle 21.
  • a vertical crease or fold line 24 is created along the front wall of the bag in alignment with the center or depth fold of the gusset l3 and a similar vertical crease or fold line 25 is created along the front bag wall in alignment with the center or depth fold of the gusset 16.
  • FIG. 7 of the drawings where the gussets l3 and 16 are opened outwardly and returned to their original positions. It will be noted however that this same opening or return folding operation also extends across the two triangular portions 20 and 21 and, as shown clearly in FIG. 8 of the drawings, the extremity of the sealed bottom edge 19 within each triangular portion assumes a vertical position centrally of the respective gusseted portions 13 and 16.
  • the halves of the folded triangular portions 20 and 21 are mirror images of each other.
  • the triangular portion 20 has an angular edge 26 extending at right angles with respect to the edge 22 and the upper extremities of these triangular portions are contiguous with the folded edge 27 which is parallel to the bottom seal 19 and extends the full width of the gusset l3.
  • the triangular portion 22 has an angularly directed folded edge 28 also disposed as a right angular or 90' relationship with respect to the folded edge 23 and the upper extremities of the edges 28 and 23 are contiguous with the folded line 29 extending across the full width of the gusset 16 and also disposed in parallel relationship with respect to the sealed bottom 19.
  • the lower extremity of the sealed bag is then folded upwardly and transversely from edge to edge, as indicated at FIG. 9 of the bag, to create a folded line 30 extending across the entire front wall of the bag and a companion fold line 31 extending across the entire rear wall of the bag, the location or plane of these fold lines 30 and 31 being in the identical plane as the folded edges of the triangular portions 27 and 29, respectively, of the triangular portions 20 and 21.
  • FIG. 1 of the drawings A simple grasping of one wall of the bag mouth and a swinging, opening operation, will produce a self-' supporting flat-bottom plastic bag, when an article or the like will have been placed therein, the lower portion of which is illustrated in FIG. 1 of the drawings.
  • transverse fold lines 30 and 31 are critical since the distance between the bottom seal 19 and these transverse fold lines which are parallel to said bottom sealed edge must be substantially identical to the depth of the gussets 13 and 16, simultaneously produces contiguous fold lines 32 and 33 which extend, respectively, across the associated gussets.
  • the flat bottom of the opened bag is defined by (a) the fold line 30 extending across the bag front wall 11, (b) the fold line 31 extending across the bag rear wall 12, (c) a fold line 32 extending across the gusset l3, and (d) the fold line 33 extending across the gusset 16.
  • the vertical edges of the opened bag are defined by the edge folds of the opened gussets 13 and 16 and the depth of the opened bag is determined by the width of the flat bottom portion which is identical to that of the fully opened or extended gussets.
  • the film blowing, gusseting and flattening, and bag forming can be completed in line as a continuous operation.
  • the gusseted flat tube may be provided in roll form or sealed and severed lengths may be fed to the apparatus from a stacked supply thereof. While the continuous method of operation will make for improved economy, under any of these circumstances a superior fiat-bottom plastic bag can be provided with sufficient economy to compete more than favorably with paper bags manufactured in accordance with present-day practices.
  • the plastic bag will have greater strength, complete resistance to rupture under stresses vastly in excess of those to be expected under normal conditions, and will be fluid-proof as against both internal and external adverse influences. Bags of this character may be manufactured with equal facility through a particularly wide range of sizes with appropriate adjustment of the apparatus to compensate for bag width, length, and gusset depth.
  • thermoplastic film having satisfactory properties of strength, stiffness and heat scalability can be used in accordance with this invention, such as polyolefins, polyamides (nylon), polyvinyl chlorides, polyvinylidene chlorides, polyesters, polycarbonates, and polystyrene, and the like.
  • Polypropylene and polyethylene are preferred.
  • Linear high density polyethylene having a density in the range of about 0.945 to 0.960 is especially preferred.
  • Typical properties of films found to be satisfactory for the present invention are:
  • the thickness of the film is not critical and will vary with the other properties depending on the desired stiffness and strength of the bag. Economy will be another factor which determines how thick the film will be. Typical thicknesses are in the range of about 1.0 to about 5.0 mils.
  • reverse fold plastic bags may be in the form of a continuous roll where a perforation or the like is provided immediately adjacent each bottom heat seal and successive bags can be separated from the prefabricated endless roll or length, with particular convenience, as required.
  • a length of prefabricated bags also could be packaged in either flat or roll form in a despenser box for convenient home or commercial use.
  • thermoplastic material which includes the steps of:

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Bag Frames (AREA)
  • Making Paper Articles (AREA)
US00243946A 1972-04-14 1972-04-14 Flat-bottom plastic bags and method for the production thereof Expired - Lifetime US3799042A (en)

Priority Applications (9)

Application Number Priority Date Filing Date Title
US00243946A US3799042A (en) 1972-04-14 1972-04-14 Flat-bottom plastic bags and method for the production thereof
BE129916A BE798095A (fr) 1972-04-14 1973-04-11 Sacs en matiere plastique a fond plat et procede de fabrication de ces sacs
FR7313441A FR2180402A5 (de) 1972-04-14 1973-04-13
IT23006/73A IT982766B (it) 1972-04-14 1973-04-13 Procedimento per produrre un sac chetto di materiale termoplastico
NL7305201A NL7305201A (de) 1972-04-14 1973-04-13
SE7305323A SE7305323L (de) 1972-04-14 1973-04-13
JP48041493A JPS4919976A (de) 1972-04-14 1973-04-13
LU67422A LU67422A1 (de) 1972-04-14 1973-04-13
US413467A US3917159A (en) 1972-04-14 1973-11-07 Reverse fold self-opening plastic square bottom bag

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US00243946A US3799042A (en) 1972-04-14 1972-04-14 Flat-bottom plastic bags and method for the production thereof

Publications (1)

Publication Number Publication Date
US3799042A true US3799042A (en) 1974-03-26

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ID=22920756

Family Applications (1)

Application Number Title Priority Date Filing Date
US00243946A Expired - Lifetime US3799042A (en) 1972-04-14 1972-04-14 Flat-bottom plastic bags and method for the production thereof

Country Status (8)

Country Link
US (1) US3799042A (de)
JP (1) JPS4919976A (de)
BE (1) BE798095A (de)
FR (1) FR2180402A5 (de)
IT (1) IT982766B (de)
LU (1) LU67422A1 (de)
NL (1) NL7305201A (de)
SE (1) SE7305323L (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4273550A (en) * 1978-03-24 1981-06-16 Union Carbide Corporation Method for producing a flat bottom plastic bag
GB2362351A (en) * 2000-03-18 2001-11-21 Harris Parts Ltd Extruded tubular packaging

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5196177A (en) * 1975-02-20 1976-08-23 Jutanno kuriiningusochi
JPS52139672U (de) * 1976-04-19 1977-10-22
CA1114215A (en) * 1978-03-24 1981-12-15 Ewald A. Kamp Method for producing a flat bottom plastic bag
JPS5541838A (en) * 1978-09-18 1980-03-24 Kubota Ltd Inner surface brushing method of cement lining pipe

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US502847A (en) * 1893-08-08 Paper-bag machine
US689998A (en) * 1900-12-01 1901-12-31 Charles F Coburn Bag-machine.
US711369A (en) * 1900-06-28 1902-10-14 Union Paper Bag Machine Co Paper-bag machine.
US3136475A (en) * 1961-01-16 1964-06-09 Bemis Bro Bag Co Bag bottom closure having a v-shaped bottom
US3435736A (en) * 1965-10-11 1969-04-01 Erwin W P Reiche Method of making a square bottom bag
US3606822A (en) * 1970-01-12 1971-09-21 Nat Distillers Chem Corp Method and apparatus for producing a flat-bottom plastic bag
US3618478A (en) * 1969-07-31 1971-11-09 Continental Can Co Three dimensional bag with reinforced bottom and method of forming same
US3680445A (en) * 1970-06-05 1972-08-01 Apl Corp Method and apparatus for manufacturing shopping bag

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US502847A (en) * 1893-08-08 Paper-bag machine
US711369A (en) * 1900-06-28 1902-10-14 Union Paper Bag Machine Co Paper-bag machine.
US689998A (en) * 1900-12-01 1901-12-31 Charles F Coburn Bag-machine.
US3136475A (en) * 1961-01-16 1964-06-09 Bemis Bro Bag Co Bag bottom closure having a v-shaped bottom
US3435736A (en) * 1965-10-11 1969-04-01 Erwin W P Reiche Method of making a square bottom bag
US3618478A (en) * 1969-07-31 1971-11-09 Continental Can Co Three dimensional bag with reinforced bottom and method of forming same
US3606822A (en) * 1970-01-12 1971-09-21 Nat Distillers Chem Corp Method and apparatus for producing a flat-bottom plastic bag
US3680445A (en) * 1970-06-05 1972-08-01 Apl Corp Method and apparatus for manufacturing shopping bag

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4273550A (en) * 1978-03-24 1981-06-16 Union Carbide Corporation Method for producing a flat bottom plastic bag
GB2362351A (en) * 2000-03-18 2001-11-21 Harris Parts Ltd Extruded tubular packaging
GB2362351B (en) * 2000-03-18 2004-01-14 Harris Parts Ltd Extruded packaging material

Also Published As

Publication number Publication date
NL7305201A (de) 1973-10-16
IT982766B (it) 1974-10-21
FR2180402A5 (de) 1973-11-23
SE7305323L (de) 1973-10-15
JPS4919976A (de) 1974-02-21
BE798095A (fr) 1973-10-11
LU67422A1 (de) 1973-06-18

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