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US3067079A - Thermoplastic seam - Google Patents

Thermoplastic seam Download PDF

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Publication number
US3067079A
US3067079A US104927A US10492761A US3067079A US 3067079 A US3067079 A US 3067079A US 104927 A US104927 A US 104927A US 10492761 A US10492761 A US 10492761A US 3067079 A US3067079 A US 3067079A
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United States
Prior art keywords
sheet material
edge
seam
sheet
edge margin
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Expired - Lifetime
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US104927A
Inventor
Hyman G Chinn
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Union Carbide Corp
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Union Carbide Corp
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Priority claimed from US749274A external-priority patent/US3018212A/en
Application filed by Union Carbide Corp filed Critical Union Carbide Corp
Priority to US104927A priority Critical patent/US3067079A/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
    • B29C65/02—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
    • B29C65/40—Applying molten plastics, e.g. hot melt
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/01—General aspects dealing with the joint area or with the area to be joined
    • B29C66/05—Particular design of joint configurations
    • B29C66/10—Particular design of joint configurations particular design of the joint cross-sections
    • B29C66/11—Joint cross-sections comprising a single joint-segment, i.e. one of the parts to be joined comprising a single joint-segment in the joint cross-section
    • B29C66/112—Single lapped joints
    • B29C66/1122—Single lap to lap joints, i.e. overlap joints
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/01—General aspects dealing with the joint area or with the area to be joined
    • B29C66/05—Particular design of joint configurations
    • B29C66/10—Particular design of joint configurations particular design of the joint cross-sections
    • B29C66/11—Joint cross-sections comprising a single joint-segment, i.e. one of the parts to be joined comprising a single joint-segment in the joint cross-section
    • B29C66/114—Single butt joints
    • B29C66/1142—Single butt to butt joints
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/40—General aspects of joining substantially flat articles, e.g. plates, sheets or web-like materials; Making flat seams in tubular or hollow articles; Joining single elements to substantially flat surfaces
    • B29C66/41—Joining substantially flat articles ; Making flat seams in tubular or hollow articles
    • B29C66/43—Joining a relatively small portion of the surface of said articles
    • B29C66/432—Joining a relatively small portion of the surface of said articles for making tubular articles or closed loops, e.g. by joining several sheets ; for making hollow articles or hollow preforms
    • B29C66/4322—Joining a relatively small portion of the surface of said articles for making tubular articles or closed loops, e.g. by joining several sheets ; for making hollow articles or hollow preforms by joining a single sheet to itself
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/40—General aspects of joining substantially flat articles, e.g. plates, sheets or web-like materials; Making flat seams in tubular or hollow articles; Joining single elements to substantially flat surfaces
    • B29C66/41—Joining substantially flat articles ; Making flat seams in tubular or hollow articles
    • B29C66/43—Joining a relatively small portion of the surface of said articles
    • B29C66/432—Joining a relatively small portion of the surface of said articles for making tubular articles or closed loops, e.g. by joining several sheets ; for making hollow articles or hollow preforms
    • B29C66/4329—Joining a relatively small portion of the surface of said articles for making tubular articles or closed loops, e.g. by joining several sheets ; for making hollow articles or hollow preforms the joint lines being transversal but non-orthogonal with respect to the axis of said tubular articles, i.e. being oblique
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/40—General aspects of joining substantially flat articles, e.g. plates, sheets or web-like materials; Making flat seams in tubular or hollow articles; Joining single elements to substantially flat surfaces
    • B29C66/49—Internally supporting the, e.g. tubular, article during joining
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/70—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material
    • B29C66/72—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the structure of the material of the parts to be joined
    • B29C66/723—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the structure of the material of the parts to be joined being multi-layered
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/80—General aspects of machine operations or constructions and parts thereof
    • B29C66/83—General aspects of machine operations or constructions and parts thereof characterised by the movement of the joining or pressing tools
    • B29C66/834—General aspects of machine operations or constructions and parts thereof characterised by the movement of the joining or pressing tools moving with the parts to be joined
    • B29C66/8341—Roller, cylinder or drum types; Band or belt types; Ball types
    • B29C66/83411—Roller, cylinder or drum types
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C53/00—Shaping by bending, folding, twisting, straightening or flattening; Apparatus therefor
    • B29C53/56—Winding and joining, e.g. winding spirally
    • B29C53/58—Winding and joining, e.g. winding spirally helically
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/70—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material
    • B29C66/72—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the structure of the material of the parts to be joined
    • B29C66/723—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the structure of the material of the parts to be joined being multi-layered
    • B29C66/7232—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the structure of the material of the parts to be joined being multi-layered comprising a non-plastics layer
    • B29C66/72321—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the structure of the material of the parts to be joined being multi-layered comprising a non-plastics layer consisting of metals or their alloys
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/70—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material
    • B29C66/72—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the structure of the material of the parts to be joined
    • B29C66/723—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the structure of the material of the parts to be joined being multi-layered
    • B29C66/7232—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the structure of the material of the parts to be joined being multi-layered comprising a non-plastics layer
    • B29C66/72327—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the structure of the material of the parts to be joined being multi-layered comprising a non-plastics layer consisting of natural products or their composites, not provided for in B29C66/72321 - B29C66/72324
    • B29C66/72328—Paper
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2711/00—Use of natural products or their composites, not provided for in groups B29K2601/00 - B29K2709/00, for preformed parts, e.g. for inserts
    • B29K2711/12—Paper, e.g. cardboard
    • B29K2711/126—Impregnated
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2009/00—Layered products
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2023/00—Tubular articles
    • B29L2023/22—Tubes or pipes, i.e. rigid

Definitions

  • This invention relates to thermoplastic edged webs and thermoplastic lined containers and a method for their manufacture.
  • thermoplastic coatings over both the surface and the edges of sheet material have heretofore been generally unsatisfactory and difiicult to obtain.
  • continuous thermoplastic coatings have been impossible to obtain. Coating the fiat expanse of sheet material faces is easily accomplished, but the edges of the sheet material web cannot be successfully coated with thermoplastic by any of the presently known coating techniques.
  • bonds employed to join or seal webs of sheet material
  • a butt-joint or edge-to-edge bond and a lap joint or edge margin-over-edge margin bond wherein the portion of sheet material immediately adjacent to the edge, or edge margin, is lapped over the corresponding portion of the sheet material web.
  • a web of sheet material is folded lengthwise and the opposite edge margins are brought into contact with one another and bonded with a suitable adhesive.
  • a suitable adhesive there is a seam running the entire length of the bag. If the bag is fabricated from sheet material coated on the inner side, a continuous thermoplastic lining would be obtained if a suitable bond were made between the edges.
  • a lap joint is employed because it affords greater strength than butt joint bonds, and in many applications the extra bulk at the seam which invariably accompanies lap joints is not harmful. Whether bulky or not, the lap joint exposes an edge of the Web inside the container which, if uncoated, breaks the continuity of the thermoplastic lining and defeats the purpose of the coating. Bags with discontinuous linings are prone to unsightly staining and physical weakening due to seepage of the contents. Because a butt joint generally lacks the necessary strength for most bag making and similar applications, it is not so widely used, although with such a joint adjacent, uncoated edges are co-extensive and are thus not exposed to the container contents and a bond of less bulk is obtained.
  • a bag with a long seam is only one of the many types of containers in which the problem of exposed uncoated edges arises.
  • Others are spiral wound containers and convolute containers which offer greater rigidity and strength but are subject to the same limitations as bags with regards to liquid and semi-liquid goods. Also, in these containers, the bulk of a lap joint can become a serious drawback.
  • a very particular object of my invention is to provide containers having a continuous plastic lining throughout.
  • edge margin of the sheet material and the remainder of the flattened bead extends outwardly from the web edge
  • the sheet material can be fabricated into a container by placing a skirted sheet material edge adjacent to a second sheet material edge in such manner that the skirt of said skirted sheet material edge overlaps the edge margin of said second sheet ma-. terial edge and placing adhesive therebetween and simultaneously pressing said skirt and said edge margin against said adhesive to form a joint therebetween.
  • the method of my invention utilizes one and preferably two extruders.
  • the first extruder places a head of resin upon a travelling web of sheet material near the edge.
  • the bead after flattening adheres firmly to the sheet material and is sufliciently solidified to extend outwardly without outside support as a skirt.
  • the second extruder places a bead of hot resin between said skirt and a second web edge margin and said skirt and edge margin are then pressed against the hot bead and become firmly bonded together thereby. Additionally, in those instances in which the two web edges are aligned in substantially abutting relation, some of the resin from the second extruder may be squeezed between said edges and form a bond therebetween as well.
  • the bond when formed, possesses the valuable attributes of both an overlap seal and a butt joint seal and also avoids the disadvantages of both.
  • the bond possesses great strength, is uniform, does not leak, does not expose an uncoated surface, is easily applied, is not bulky, and is universally adaptable. This combination of qualities has not been attained before.
  • the joint produced by the method of my invention is ideal in containers which are to package liquid, semi-liquid, and/or chemically active goods.
  • the method is extremely versatile in that the extruded head can be any thermoplastic composition and can be applied to virtually any web of sheet material, regardless of thickness, whether single or multi-ply, e.g., paper, metal foil, coated paper, and laminates.
  • the width and thickness of both the portion of the flattened bead adhering to the web and the portion protruding outwardly from the web, i.e., the skirt, can be exactly controlled during the process.
  • FIGURE 1 is a diagrammatic isometric view of the apparatus according to and for carrying out the method of the preferred embodiment of the present invention
  • FIGURE 2 is a section taken along the line 22 of FIGURE 1,
  • FIGURE 3 is a pictorial view of the preferred embodiment of a product of the method of my invention.
  • FIGURE 4 is a section taken along the line 4-4 of FIGURE 3.
  • FIG. 1 The method of my invention as particularly adapted to the formation of spiral wound containers is shown in FIGURE 1. From a consideration of the figure, it will be seen that sheet material is withdrawn from a supply roll 12 at a constant rate along a predetermined path. An extruder, not shown, with nozzle 14 is positioned above the travelling web of sheet material 10 so as to be approximately A; inch from the edge of the sheet material 10. A bead of molten resin 16 is forced from the nozzle 14 onto the sheet material 10 which advances with the resin bead 16 through the nip of a pair of pinch rolls 18. The pinch rolls 18 serve to flatten the resin bead 16, causing it to adhere to the sheet material 10 and to extend outwardly from the sheet material 10 in a selfsupporting manner as a skirt 20. The relation of the skirt 20 and the sheet material 10 is best shown in FIG- URE 2.
  • the sheet material 10 with skirt 20 is wound around fixed mandrel 22.
  • a paraffin-waxed paper slip sheet 24 is wound simultaneously with and slightly ahead of the sheet material 10 to ensure easy removal of the tube formed.
  • a second extruder or sealer with nozzle 26 places adhesive bead 28' on the skirt 20 of sheet material 10. Winding of sheet material 10 about the mandrel 22 is accomplished in a manner which places edge margin 34 adjacent to edge margin 36.
  • edge margins 34 and 36 are in abutting relation, however, it is within the scope of my invention for edge margins 34 and 36 to be in overlapping relation.
  • skirt 20 is positioned in contact with slip sheet 24 against mandrel 22. Successive turns of sheet material 10 place edge margin 36 of sheet material 10 in overlapping relation with skirt 20.
  • the nozzle 26 places a bead of adhesive between skirt 20 and the next turn of sheet material 10.
  • the pressure induced by the winding action forces edge margin 36 against skirt 26 to form a bond such as shown in FIGURE 4.
  • the bond hardens and the spiral wound container is cut as withdrawn from the mandrel and appears in FIGURE 3.
  • a sheet material container having a moisture proof seam comprising contoured sheet material and wherein adjacent edges of said sheet material define a seam and extending from the edge margin of the first sheet to the edge margin of the second sheet across said seam a hardened, self-supporting skirt of thermoplastic which is heat and pressure bonded to the edge margin of said first sheet and adhesive bonded to the edge margin of said second sheet.
  • a tubular sheet material container having a moisture proof seam comprising spiral wound sheet material and wherein adjacent edges of said Wound sheet material define a seam and extending from the edge margin of one turn of the sheet material to the edge margin of the next turn of the sheet material across said seam a hardened, self-supporting skirt of thermoplastic which is heat and pressure bonded to one edge margin and adhesive bonded to the other edge margin.
  • tubular sheet material container claimed in claim 4 wherein the entire interior surface of the container is plastic coated.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Lining Or Joining Of Plastics Or The Like (AREA)

Description

Dec. 4, 1962 H. G. CHINN THERMOPLASTIC SEAM Original Filed July 17, 1958 INVENTOR HYMAN G. CHINN A 7'7'ORNE Y United States Patent Ofitice 3,067,079 Patented Dec. 4, 1962 THERMOPLASTIC SEAM Hyman G. Chinn, Somerviile, N.J., assignor to Union Carbide Corporation, a corporation of New York Original application July 17, 1958, Ser. No. 749,274, now Patent No. 3,018,212, dated Jan. 23, 1962. Divided and this application Apr. 24, 1961, Ser. No. 104,927
5 Claims. (Cl. 154-43) This invention relates to thermoplastic edged webs and thermoplastic lined containers and a method for their manufacture.
This is a divisional application of my copending application Serial No. 749,274, filed July 17, 1958, now US. Patent 3,018,212, issued January 23, 1962.
Continuous thermoplastic coatings over both the surface and the edges of sheet material have heretofore been generally unsatisfactory and difiicult to obtain. In certain instances, as when the sheet material has been fabricated into a container, continuous thermoplastic coatings have been impossible to obtain. Coating the fiat expanse of sheet material faces is easily accomplished, but the edges of the sheet material web cannot be successfully coated with thermoplastic by any of the presently known coating techniques.
The presence of a discontinuity in a coating such as is created by an uncoated and exposed sheet material edge almost completely nullifies the advantages realized from coating the sheet material faces. Uncoated sheet ma terial edges are a point, in an otherwise completely coated container, at which leakage can develop, if the packaged contents are liquid or even semi-liquid. In addition, contamination of the contents by the elution of chemicals from the sheet material is a distinct possibility. Thus the presence of even one uncoated edge interrupts the inert, chemically resistant, moisture and vapor impermeable barrier which resin coatings, when continuous, provide.
Inaccessibility of the edges, particularly after the sheet material has been fabricated into a container, and coincidence of a sheet material edge with a container edge preclude use ,of spray coating techniques which are awkward, time consuming, and unreliable in these applications. Further, with thermoplastic resins, such as polyethylene, a problem of adhesion to nonmetallic substrates arises, rendering spray-coating techniques even less desirable. In other applications, such as coating of sharpedged webs with plastic to prevent their cutting, a convenient, widely adaptable method is not known. Dip coating techniques such as are used with wax coatings are not practicable with thermoplastics.
There are two general types of bonds employed to join or seal webs of sheet material, a butt-joint or edge-to-edge bond, and a lap joint or edge margin-over-edge margin bond wherein the portion of sheet material immediately adjacent to the edge, or edge margin, is lapped over the corresponding portion of the sheet material web. In the fabrication of a paper bag, for example, a web of sheet material is folded lengthwise and the opposite edge margins are brought into contact with one another and bonded with a suitable adhesive. Thus there is a seam running the entire length of the bag. If the bag is fabricated from sheet material coated on the inner side, a continuous thermoplastic lining would be obtained if a suitable bond were made between the edges. Generally a lap joint is employed because it affords greater strength than butt joint bonds, and in many applications the extra bulk at the seam which invariably accompanies lap joints is not harmful. Whether bulky or not, the lap joint exposes an edge of the Web inside the container which, if uncoated, breaks the continuity of the thermoplastic lining and defeats the purpose of the coating. Bags with discontinuous linings are prone to unsightly staining and physical weakening due to seepage of the contents. Because a butt joint generally lacks the necessary strength for most bag making and similar applications, it is not so widely used, although with such a joint adjacent, uncoated edges are co-extensive and are thus not exposed to the container contents and a bond of less bulk is obtained.
A bag with a long seam is only one of the many types of containers in which the problem of exposed uncoated edges arises. Others are spiral wound containers and convolute containers which offer greater rigidity and strength but are subject to the same limitations as bags with regards to liquid and semi-liquid goods. Also, in these containers, the bulk of a lap joint can become a serious drawback.
It is an object, therefore, of my invention to provide a method for forming a bond between webs of sheet material which possesses the advantages but not the drawbacks of both the butt joint and the lap joint.
It is another object of my invention to provide a joint between webs of sheet material which is. moisture impermeable, non-bulky, and strong.
A very particular object of my invention is to provide containers having a continuous plastic lining throughout.
These and other objects are accomplished in accordance with my invention by extruding a bead of a thermoplastic onto the edge margin of a web of sheet. material and flattening the extruded bead, as by a pair of pinch rolls,
so that a portion of the flattened bead adheres to the web.
edge margin of the sheet material and the remainder of the flattened bead extends outwardly from the web edge,
margin as a skirt. Thereafter the sheet material can be fabricated into a container by placing a skirted sheet material edge adjacent to a second sheet material edge in such manner that the skirt of said skirted sheet material edge overlaps the edge margin of said second sheet ma-. terial edge and placing adhesive therebetween and simultaneously pressing said skirt and said edge margin against said adhesive to form a joint therebetween.
The method of my invention utilizes one and preferably two extruders. The first extruder places a head of resin upon a travelling web of sheet material near the edge. The bead after flattening adheres firmly to the sheet material and is sufliciently solidified to extend outwardly without outside support as a skirt. The second extruder places a bead of hot resin between said skirt and a second web edge margin and said skirt and edge margin are then pressed against the hot bead and become firmly bonded together thereby. Additionally, in those instances in which the two web edges are aligned in substantially abutting relation, some of the resin from the second extruder may be squeezed between said edges and form a bond therebetween as well. The bond, when formed, possesses the valuable attributes of both an overlap seal and a butt joint seal and also avoids the disadvantages of both. The bond possesses great strength, is uniform, does not leak, does not expose an uncoated surface, is easily applied, is not bulky, and is universally adaptable. This combination of qualities has not been attained before. The joint produced by the method of my invention is ideal in containers which are to package liquid, semi-liquid, and/or chemically active goods.
The method is extremely versatile in that the extruded head can be any thermoplastic composition and can be applied to virtually any web of sheet material, regardless of thickness, whether single or multi-ply, e.g., paper, metal foil, coated paper, and laminates. The width and thickness of both the portion of the flattened bead adhering to the web and the portion protruding outwardly from the web, i.e., the skirt, can be exactly controlled during the process.
Additional advantages will become apparent from a consideration of the detailed description below of one embodiment of the invention which is described in conjunction with the attached drawings in which:
FIGURE 1 is a diagrammatic isometric view of the apparatus according to and for carrying out the method of the preferred embodiment of the present invention,
' FIGURE 2 is a section taken along the line 22 of FIGURE 1,
FIGURE 3 is a pictorial view of the preferred embodiment of a product of the method of my invention, and
FIGURE 4 is a section taken along the line 4-4 of FIGURE 3. a
The method of my invention as particularly adapted to the formation of spiral wound containers is shown in FIGURE 1. From a consideration of the figure, it will be seen that sheet material is withdrawn from a supply roll 12 at a constant rate along a predetermined path. An extruder, not shown, with nozzle 14 is positioned above the travelling web of sheet material 10 so as to be approximately A; inch from the edge of the sheet material 10. A bead of molten resin 16 is forced from the nozzle 14 onto the sheet material 10 which advances with the resin bead 16 through the nip of a pair of pinch rolls 18. The pinch rolls 18 serve to flatten the resin bead 16, causing it to adhere to the sheet material 10 and to extend outwardly from the sheet material 10 in a selfsupporting manner as a skirt 20. The relation of the skirt 20 and the sheet material 10 is best shown in FIG- URE 2.
In order to form a spiral wound container such as shown in FIGURE 3, the sheet material 10 with skirt 20 is wound around fixed mandrel 22. A paraffin-waxed paper slip sheet 24 is wound simultaneously with and slightly ahead of the sheet material 10 to ensure easy removal of the tube formed. A second extruder or sealer with nozzle 26 places adhesive bead 28' on the skirt 20 of sheet material 10. Winding of sheet material 10 about the mandrel 22 is accomplished in a manner which places edge margin 34 adjacent to edge margin 36. In the specific embodiment shown, the edges of the respective edge margins 34 and 36 are in abutting relation, however, it is within the scope of my invention for edge margins 34 and 36 to be in overlapping relation. In FIGURE 1, as the sheet material 10 is wound, skirt 20 is positioned in contact with slip sheet 24 against mandrel 22. Successive turns of sheet material 10 place edge margin 36 of sheet material 10 in overlapping relation with skirt 20. The nozzle 26 places a bead of adhesive between skirt 20 and the next turn of sheet material 10. The pressure induced by the winding action forces edge margin 36 against skirt 26 to form a bond such as shown in FIGURE 4. The bond hardens and the spiral wound container is cut as withdrawn from the mandrel and appears in FIGURE 3.
Various modifications such as formation of two skirts simultaneously and alternate embodiments of our invention such as bag and convolute wound container manufacture are obvious to those skilled in the art.
The scope of my invention, therefore, is not limited except as defined in the appended claims.
What is claimed is:
1. A sheet material container having a moisture proof seam comprising contoured sheet material and wherein adjacent edges of said sheet material define a seam and extending from the edge margin of the first sheet to the edge margin of the second sheet across said seam a hardened, self-supporting skirt of thermoplastic which is heat and pressure bonded to the edge margin of said first sheet and adhesive bonded to the edge margin of said second sheet.
2. The sheet material container claimed in claim 1, wherein the seam is a lap joint seam.
3. The sheet material container claimed in claim 1 wherein the seam is a butt joint seam;
4. A tubular sheet material container having a moisture proof seam comprising spiral wound sheet material and wherein adjacent edges of said Wound sheet material define a seam and extending from the edge margin of one turn of the sheet material to the edge margin of the next turn of the sheet material across said seam a hardened, self-supporting skirt of thermoplastic which is heat and pressure bonded to one edge margin and adhesive bonded to the other edge margin.
5. The tubular sheet material container claimed in claim 4 wherein the entire interior surface of the container is plastic coated.
References Cited in the file of this patent UNITED STATES PATENTS 2,415,906 Paige Feb. 18, 1947 2,677,633 Gross May 4, 1954 2,943,540 McBain July 5, 1960

Claims (1)

1. A SHEET MATERIAL CONTAINER HAVING A MOISTURE PROOF SEAM COMPRISING CONTOURED SHEET MATERIAL AND WHEREIN ADJACENT EDGES OF SAID SHEET MATERIAL DEFINE A SEAM AND EXTENDING FROM THE EDGE MARGIN OF THE FIRST SHEET TO THE EDGE MARGIN OF THE SECOND SHEET ACROSS SAID SEAM A HARDENED, SELF-SUPPORTING SKIRT OF THERMOPLASTRIC WHICH IS HEAT AND PRESSURE BONDED TO THE EDGE MARGIN OF SAID FIRST SHEET AND ADHESIVE BONDED TO THE EDGE MARGIN OF SAID SECOND SHEET.
US104927A 1958-07-17 1961-04-24 Thermoplastic seam Expired - Lifetime US3067079A (en)

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US749274A US3018212A (en) 1958-07-17 1958-07-17 Thermoplastic bonding and coating
US104927A US3067079A (en) 1958-07-17 1961-04-24 Thermoplastic seam

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3498521A (en) * 1967-12-11 1970-03-03 Lester D Gill Carton with plastic sealing
US5205340A (en) * 1989-06-27 1993-04-27 Brown Foundry System, Inc. Insulated paper sleeve for casting metal articles in sand molds
US20110097526A1 (en) * 2009-10-28 2011-04-28 Jonathan Goering Fiber preform, fiber reinforced composite, and method of making thereof

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2415906A (en) * 1943-04-07 1947-02-18 Richard E Paige Head construction for collapsible tubes
US2677633A (en) * 1950-08-07 1954-05-04 Rohr Aircraft Corp Processes for sealing the seams and joints of structures fabricated of nonporous materials
US2943540A (en) * 1958-01-24 1960-07-05 W C Ritchie & Co Method of making a spirally wound container

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2415906A (en) * 1943-04-07 1947-02-18 Richard E Paige Head construction for collapsible tubes
US2677633A (en) * 1950-08-07 1954-05-04 Rohr Aircraft Corp Processes for sealing the seams and joints of structures fabricated of nonporous materials
US2943540A (en) * 1958-01-24 1960-07-05 W C Ritchie & Co Method of making a spirally wound container

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3498521A (en) * 1967-12-11 1970-03-03 Lester D Gill Carton with plastic sealing
US5205340A (en) * 1989-06-27 1993-04-27 Brown Foundry System, Inc. Insulated paper sleeve for casting metal articles in sand molds
US20110097526A1 (en) * 2009-10-28 2011-04-28 Jonathan Goering Fiber preform, fiber reinforced composite, and method of making thereof
US9186850B2 (en) * 2009-10-28 2015-11-17 Albany Engineered Composites, Inc. Fiber preform, fiber reinforced composite, and method of making thereof

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