EP0447209B1 - Enveloppe munie d'une tirette d'ouverture - Google Patents

Enveloppe munie d'une tirette d'ouverture Download PDF

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Publication number
EP0447209B1
EP0447209B1 EP19910302114 EP91302114A EP0447209B1 EP 0447209 B1 EP0447209 B1 EP 0447209B1 EP 19910302114 EP19910302114 EP 19910302114 EP 91302114 A EP91302114 A EP 91302114A EP 0447209 B1 EP0447209 B1 EP 0447209B1
Authority
EP
European Patent Office
Prior art keywords
tear
envelope
sheetstock
weakness
lines
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
EP19910302114
Other languages
German (de)
English (en)
Other versions
EP0447209A1 (fr
Inventor
Wayne K. C/O Minnesota Mining And Morris
Donald J. C/O Minnesota Mining And Klassen
Richard L. Jr. C/O Minnesota Mining And Sheehan
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.)
3M Co
Original Assignee
Minnesota Mining and Manufacturing Co
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 Minnesota Mining and Manufacturing Co filed Critical Minnesota Mining and Manufacturing Co
Publication of EP0447209A1 publication Critical patent/EP0447209A1/fr
Application granted granted Critical
Publication of EP0447209B1 publication Critical patent/EP0447209B1/fr
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
    • B65D27/00—Envelopes or like essentially-rectangular containers for postal or other purposes having no structural provision for thickness of contents
    • B65D27/32—Opening devices incorporated during envelope manufacture
    • B65D27/38—Tearing-strings or -strips

Definitions

  • the invention concerns a tear-open mailing envelope. More specifically, the invention concerns an envelope that has a tear strip at lines of weakness in the sheetstock of which the envelope is made.
  • the presently preferred sheetstock for tear-resistant mailing envelopes is spunbonded polyolefin which is sold by E.I. du Pont de Nemours under the trademark "Tyvek”. It is so resistant to tearing that it must be formed with lines of weakness to be torn open by a tear strip, but it delaminates fairly easily and thus tends to leave visual evidence of any attempt to surreptitiously open a flap or a seam.
  • the present invention provides a mailing envelope that is made of tear-resistant sheetstock and can easily be opened by a tear strip, but won't open accidentally.
  • the tear-open feature of the invention should be more economical to manufacture, because it employs only one tape, instead of two. It should also leave smoother edges at the opening.
  • mailing envelope is here used to encompass shipping bags and any other shipping container made with a tear-resistant sheetstock such as "Tyvek” spunbonded polyolefin.
  • a tear-open mailing envelope comprising tear-resistant sheetstock having a pair of closely spaced parallel lines of weakness formed in the sheetstock and a length of flexible reinforcing tape bonded over said pair of lines of weakness in the longitudinal direction thereof, characterised in that:- said tape readily tears longitudinally while being highly resistant to transverse tearing so that only a strip of reinforcing tape that lies between said lines is torn off to open the envelope.
  • a method of making a tear-open mailing envelope of tear-resistant sheetstock including the steps of forming in the sheetstock a pair of closely spaced parallel lines of weakness and cutting, folding, and sealing said tear-resistant sheetstock to form the envelope, characterised by the step of; (a) bonding to the sheetstock over said lines of weakness in the longitudinal direction thereof a length of flexible tape that readily tears longitudinally while being highly resistant to transverse tearing, for reinforcing the lines of weakness and for opening the envelope.
  • the tear-open mailing envelope of the invention like that of the Morris patent, is a tear-resistant sheetstock having a pair of closely spaced parallel lines of weakness over which is bonded a length of flexible, reinforcing tape.
  • the novel tear-open mailing envelope differs from that of Morris in that the reinforcing tape has an Impact Value (as herein defined) of at least 300 N/dm, a longitudinal break strength (ASTM D-3759) of at least 1500 N/dm, readily tears longitudinally while being highly resistant to transverse tearing, and has a Tear Value (as herein defined) of less than 4 oz. (1 N) so that only a strip of the reinforcing tape that lies between said lines is torn off to open the envelope.
  • lines of weakness is here used to encompass any line at which the tear-resistant sheetstock can be easily and cleanly separated, e.g., a razor cut or a fused score line of the Morris patent. With some tear-resistant sheetstock, it may be sufficient to form closely spaced perforations or partial cuts, but uninterrupted lines of weakness that extend completely through the thickness are required when using "Tyvek” spunbonded polyolefin, the sheetstock of choice for tear-open mailing envelopes of the invention. "Tyvek” spunbonded polyolefin is currently available in thicknesses from about 0.1 to 0.2 mm, all of which have sufficient tear resistance to be useful in tear-open mailing envelopes of the invention.
  • the length of reinforcing tape is applied to cover an inner surface of the novel mailing envelope.
  • the length of reinforcing tape can be cut for a short distance along the lines of weakness which, if not already cut, are cut to allow that portion of the end of the tape to serve as a pull tab.
  • the strip of tape between the lines of weakness readily separates from the rest of the tape and acts as a tear strip through the envelope to open the envelope between the above-described parallel lines of weakness.
  • one end of the length of reinforcing tape can be left unbonded at an opening in the envelope through which the tab can be grasped to initiate the opening.
  • the reinforcing tape of the novel envelope can be any flexible tape that has the above-listed properties.
  • a preferred reinforcing tape is disclosed in EPO Pat. Publ. No. 343,896 (Minnesota Mining and Manufacturing Company) that was published Nov. 29, 1989.
  • the backing of that reinforcing tape is a polymeric film having longitudinal polymeric ribs at one surface that afford easy longitudinal tearing and excellent resistance to crosswise tearing.
  • the other surface of the backing bears an adhesive by which the tape is adhered to the novel envelope so that the ribs cleave the polymeric film when the tear strip is pulled through the envelope, thus leaving smooth edges at the opening.
  • filament-reinforced tapes such as that of US-A-2,753,284 (Pahl et al.) which has a kraft paper backing that should tear to leave smooth edges when the tear strip is pulled through the envelope.
  • Tapes having polymeric film backings that are highly tensilized longitudinally should also be useful as the reinforcing tape. Such a backing could be embossed or scored in the lengthwise direction to enhance both widthwise strength and longitudinal tearing.
  • the strip of tape that opens the novel mailing envelope is reinforced by the underlying sheetstock and accordingly has greater strength and toughness than does unreinforced tape of the same width, thus significantly minimizing any danger of breakage of the tear strip while the envelope is being opened.
  • the spacing between the lines of weakness is from 3 to 10 mm.
  • the tear strip would be more difficult to grasp and might hurt the fingers of some persons.
  • a narrow spacing would afford less sheetstock reinforcement to the tape strip, so that it would be more likely to break.
  • spacings substantially larger than 10 mm would require the reinforcing tape to be wider and hence of greater cost with no offsetting advantage.
  • the length of reinforcing tape preferably has sufficient width to extend at least 6 mm laterally beyond each of the lines of weakness in order to make the mailing envelope adequately resistant to accidental opening in use.
  • the reinforcing tape wide enough to extend substantially more than 12 mm beyond each line of weakness might be economically wasteful.
  • Mailing envelopes typically are formed from long rolls of sheetstock using apparatus that continuously cuts, folds and seals the sheetstock.
  • apparatus that continuously cuts, folds and seals the sheetstock.
  • the lines of weakness preferably are razor cuts, because to create the lines ultrasonically would be likely to require slower line speeds.
  • the lines of weakness are formed, they preferably extend in the direction of movement of the sheetstock, typically adjacent an edge of the envelope that is perpendicular to the edge that bears a flap.
  • the length of reinforcing tape that covers the lines of weakness bears an adhesive by which it can be bonded to the sheetstock of the mailing envelop.
  • that adhesive is pressure-sensitive, but it can be heat- or solvent-activated.
  • the novel tear-open mailing envelope may have only one line of weakness and to form a nick in the reinforcing tape at each side of the line of weakness to initiate tearing.
  • that single line is formed ultrasonically, it should have sufficient width to permit a strip of tape to be pulled through without hurting ones' fingers. To form such a wide line might be unduly slow and wasteful of energy. If a relatively wide line of weakness is created by cutting, the adhesive of the reinforcing tape would be exposed, and the tear strip portion of the reinforcing tape would not derive reinforcement from the sheetstock of the envelope and so would be more likely to break accidentally.
  • the mailing envelope 10 of Figs. 1 and 2 is formed of tear-resistant spunbonded polyolefin sheetstock.
  • a flap 12 bears a layer of pressure-sensitive adhesive 13 that is protected by a removable liner 14.
  • Formed in the flap are a pair of closely spaced parallel lines of weakness 16 and 17 at which the fibers of the spunbonded polyolefin have been changed to a film ultrasonically.
  • a length of reinforcing tape 18 has an adhesive layer 20 by which it has been permanently bonded to the flap to cover the lines of weakness 16 and 17. At one end, the tape has been cut at 21 over a short distance to coincide with the underlying lines of weakness which also have been cut over the same distance to create a pull tab 22 as shown in FIG. 1A.
  • the tab 22 can be pulled with ones fingertips. This separates the strip of tape between the lines of weakness from the rest of the reinforcing tape 18 so that the strip can act as a tear strip upon being pulled through the flap to open the envelope between the parallel lines of weakness.
  • the mailing envelope 30 of Figs. 3 and 4 also is formed of tear-resistant sheetstock. Adjacent an edge of the envelope that is perpendicular to the edge that bears a flap 32 are a pair of closely spaced parallel cuts 33 and 34. A length of reinforcing tape 36 has an adhesive layer 37 by which it has been permanently bonded to the inner surface of the envelope to cover the cuts 33 and 34. At one end, the tape has been cut over a short distance to coincide with the cuts in the envelope to create a pull tab 39.
  • a sample is prepared using two rectangles of "Tyvek” spunbonded polyolefin sheetstock, each 2 by 6 inches (5.1 by 15.2 cm).
  • a gap of 1/4 inch (6 mm) between long edges of the "Tyvek” polyolefin is spanned by a 6-inch (15.2 cm) length of 1-inch (2.54 cm) wide reinforcing tape to be tested.
  • This assembly is mounted between the jaws of an Instron Tensile Tester (CRE), which jaws are 1.5 inches (3.8 cm) wide and spaced 2 inches (5.1 cm) apart. The jaws are separated at a rate of 1000 inches (2.54 m) per minute.
  • the "Impact Value” is peak resistance, reported in N/dm (of jaw width).
  • a length of reinforcing tape to be tested is razor slit about 4 cm lengthwise at the center.
  • the free ends at either side of the slit are clamped to the jaws of an Instron Tensile Tester (CRE which are then separated longitudinally at a rate of 50 inches (127 cm) per minute, and the average resistance is the "Tear Value”.
  • CRE Instron Tensile Tester
  • a "2-pound Pak” Express Mail envelope was obtained from the U.S. Postal Service, made of 18-pound “Tyvek” spunbonded polyolefin sheetstock, was 39 cm in length, 31 cm in width, and had a flap.
  • two lines of weakness were formed ultrasonically across the flap.
  • the lines of weakness were 2 mm wide, 6 mm apart, and extended through the thickness of the sheetstock from a spacing of 3 mm from a first edge of the flap through the second edge of the flap.
  • a pressure-sensitive adhesive reinforcing tape one inch (2.54 cm) in width was adhered by its own adhesive as shown in Fig. 1, which tape had been made as disclosed in the above-cited Leseman EPO patent publication.
  • the reinforcing tape had an Impact Value of 490 N/dm, a longitudinal break strength of 3150 N/dm, and a Tear Value of 0.75 N.
  • a razor slit was then made through each line of weakness and the overlying tape to a distance of 1.3 cm from the second edge of the tape to provide a pull tab.
  • the tab was pulled to carry with it a tear strip from the middle of the tape and underlying envelope sheetstock until reaching the weakness-free area at the first edge of the tab, there coming to an abrupt stop that caused the tab to slip from the fingertips.
  • the torn-off portion of the flap and tear strip remained attached to the envelope to permit both to be discarded as one unit after materials had been removed from the envelope.
  • the edges of the flap at the tear were smooth. It was significantly easier to tear open the envelope of this Example 2 as compared to that of Example 1.
  • FIG. 1 An envelope identical to that of Fig. 1 was provided with a tear-open feature like that of Example 1 except that the lines of weakness were razor slits. Pulling on its tab with ones' fingertips removed the strip of tape between the razor slits and thus opened the flap, again leaving the torn-off portion of the flap and tear strip attached to the envelope, and the torn edges were smooth.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Laminated Bodies (AREA)
  • Making Paper Articles (AREA)
  • Adhesive Tapes (AREA)
  • Bag Frames (AREA)

Claims (10)

  1. Enveloppe d'expédition à ouverture par déchirure (10) fabriquée en une feuille de base résistant à la déchirure qui comporte deux lignes d'affaiblissement parallèles et peu espacées (16,17),formées dans la feuille, et une longueur de bande de renforcement souple (18) collée sur lesdites deux lignes d'affaiblissement, dans leur direction longitudinale, caractérisée en ce que :
       ladite bande de renforcement se déchire facilement dans la direction longitudinale tandis qu'elle est très résistante à la déchirure transversale,de sorte qu'une petite largeur ou un ruban seulement de la bande de renforcement, qui est situé entre lesdites lignes, est déchiré pour ouvrir l'enveloppe.
  2. Enveloppe d'expédition à ouverture par déchirure (10) suivant la revendication 1, caractérisée en outre en ce que la feuille de base est une polyoléfine non-tissée spunbonded.
  3. Enveloppe d'expédition à ouverture par déchirure (10) suivant la revendication 1, caractérisée en outre en ce que les lignes d'affaiblissement (16,17) sont ininterrompues et s'étendent complètement à travers l'épaisseur de la feuille.
  4. Enveloppe d'expédition à ouverture par déchirure (10) suivant la revendication 1, caractérisée en outre en ce que la longueur de bande de renforcement (18) est collée à une surface intérieure de l'enveloppe d'expédition (10).
  5. Enveloppe d'expédition à ouverture par déchirure (10) suivant la revendication 4, caractérisée en outre en ce que la longueur de bande de renforcement est coupée sur une courte distance le long des lignes d'affaiblissement, pour permettre à cette partie de l'extrémité de la bande de servir de languette de traction.
  6. Enveloppe d'expédition à ouverture par déchirure (10) suivant la revendication 1,caractérisée en outre en ce que la bande de renforcement (18) comprend un support en film de polymère comportant des nervures de polymère sur une surface et une couche d'adhésif sur l'autre surface, la bande étant collée à l'enveloppe par cette couche d'adhésif.
  7. Méthode de fabrication d'une enveloppe d'expédition à ouverture par déchirure (10), en feuille résistant à la déchirure, qui comprend les étapes de création de deux lignes d' affaiblissement parallèles et peu espacées (16,17) dans la feuille, et de coupe, pliage et jonction de ladite feuille résistant à la déchirure, pour former l'enveloppe, caractérisée par l'étape de :
       collage à la feuille de base, sur lesdites lignes d'affaiblissement, dans leur direction longitudinale, d'une longueur de bande flexible (18) qui se déchire facilement dans la direction longitudinale alors qu'elle est très résistante à la déchirure transversale, pour renforcer les lignes d'affaiblissement et pour ouvrir l'enveloppe.
  8. Méthode suivant la revendication 7, dans laquelle la feuille est pliée de sorte que la longueur de bande de renforcement (18) couvre une surface intérieure de l'enveloppe.
  9. Méthode suivant la revendication 8, dans laquelle les lignes d'affaiblissement (16,17) sont formées par une coupe complète à travers la feuille, sur une distance sensiblement égale à la longueur de la bande de renforcement (18).
  10. Méthode suivant la revendication 9, dans laquelle il est prévu l'étape supplémentaire de coupe d'une extrémité de la bande de renforcement (18) sur une courte distance le long des lignes d'affaiblissement (16, 17) pour créer une languette de traction.
EP19910302114 1990-03-14 1991-03-13 Enveloppe munie d'une tirette d'ouverture Expired - Lifetime EP0447209B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US49344190A 1990-03-14 1990-03-14
US493441 1990-03-14

Publications (2)

Publication Number Publication Date
EP0447209A1 EP0447209A1 (fr) 1991-09-18
EP0447209B1 true EP0447209B1 (fr) 1993-07-14

Family

ID=23960236

Family Applications (1)

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EP19910302114 Expired - Lifetime EP0447209B1 (fr) 1990-03-14 1991-03-13 Enveloppe munie d'une tirette d'ouverture

Country Status (5)

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EP (1) EP0447209B1 (fr)
JP (1) JPH05319441A (fr)
AU (1) AU645530B2 (fr)
CA (1) CA2037964A1 (fr)
DE (1) DE69100165T2 (fr)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0755868A1 (fr) * 1995-07-25 1997-01-29 Scapa Group Plc Scellage et bande d'arrachage combinée pour enveloppe et procédé pour sa fabrication
AUPO031496A0 (en) * 1996-06-07 1996-07-04 Barr, William Henry II Easy open
CA2332912C (fr) 1998-05-28 2008-10-07 3M Innovative Properties Company Bande adhesive de fermeture dechirable et recipient muni d'un tel ruban adhesif
US6354739B1 (en) 1998-05-28 2002-03-12 3M Innovative Properties Company Tear control closing tape and container with tear control closing tape
NL1014188C1 (nl) * 2000-01-26 2001-07-27 Roelof Luiten Inrichting voor het snijden en aanbrengen van zelfklevend tape.
JP4482241B2 (ja) * 2000-08-03 2010-06-16 出光興産株式会社 包装体
US6513657B2 (en) 2001-04-26 2003-02-04 3M Innovative Properties Co. Product packaging with handle-forming tearable tape system
JP4798739B2 (ja) * 2001-07-31 2011-10-19 トッパン・フォームズ株式会社 封筒

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1411495A1 (de) * 1960-05-31 1968-10-10 Reemtsma H F & Ph Aufreissstreifen fuer Verpackungen
DE3234867A1 (de) * 1982-09-21 1984-03-22 Heinz 4406 Drensteinfurt Feldhaus Leicht oeffenbarer sicherheits-briefumschlag
US4781296A (en) * 1987-05-26 1988-11-01 Minnesota Mining And Manufacturing Company Method affording an easy opening device for nonwoven thermoplastic fiber envelopes
US5079066A (en) * 1988-05-25 1992-01-07 Minnesota Mining And Manufacturing Company Tape having improved tear strength

Also Published As

Publication number Publication date
CA2037964A1 (fr) 1991-09-15
DE69100165T2 (de) 1994-01-05
AU645530B2 (en) 1994-01-20
JPH05319441A (ja) 1993-12-03
AU7293991A (en) 1991-09-19
DE69100165D1 (de) 1993-08-19
EP0447209A1 (fr) 1991-09-18

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