Adhesive-tape system for forming a tear-open strip

Abstract

An adhesive tape system, for opening cardboard packaging, having an adhesive tape A furnished on at least one side with an adhesive coating and having a film carrier, the film being a polyolefin film oriented monoaxially in the longitudinal direction of the strip, and the film comprising a mixture of an olefinic polymer and a polar nonolefinic polymer. The adhesive tape system also has an adhesive tape B furnished on at least one side with an adhesive coating and having a film carrier, wherein the adhesive tapes A and B are disposed one above the other.

Claims

1. A carton consisting of an outer liner and an inner liner, there being disposed between the liners at least one corrugation of card, furnished with an adhesive tape system consisting of: an adhesive tape A furnished on at least one side with an adhesive coating and having a film carrier, the film carrier being a film oriented monoaxially in the longitudinal direction of the strip, and the film carrier comprises a mixture of an olefinic polymer and a polar nonolefinic polymer; and an adhesive tape B furnished on at least one side with an adhesive coating and having a film carrier, wherein the adhesive tapes A and B are disposed one above the other, wherein the total width of the adhesive tape B is less than the total width of the adhesive A, wherein the adhesive tape A of the adhesive tape system is applied on the inside of the outer liner, and the adhesive tape B of the adhesive tape system is applied on the outside of the inner liner, so that the adhesive tape B is disposed beneath the adhesive tape A, and further wherein the adhesive tape A is located between the adhesive tape B and the carton.

2. The carton according to claim 1, wherein, in the film carrier of the adhesive tape A, a fraction of polar nonolefinic polymer in the mixture of the film carrier of the adhesive tape A is in the range from 5 to 50 wt %.

3. The carton according to claim 1, wherein the film carrier of the adhesive tape A and the film carrier of the adhesive tape B is a polyolefin film oriented monoaxially in the longitudinal direction of the system, and the film carrier of adhesive tape B comprises a mixture of olefinic polymer and a polar nonolefinic polymer.

4. The carton according to claim 1, wherein the film carrier of the adhesive tape A has a thickness of 15 to 200 m.

5. The carton according to claim 1, wherein, in the film carrier of the adhesive tape A, the olefinic polymer comprises at least 50 wt % of propylene.

6. The carton according to claim 1, wherein, in the film carrier of the adhesive tape A, the polar nonolefinic polymer is selected from the group consisting of polyesters, polyamides, polyoxymethylene, polyarylene sulfides, polyarylene oxides, and polyurethanes, wherein the nonolefinic polymer is semicrystalline.

7. The carton according to claim 1, wherein the film carrier of the adhesive tape B has a tensile strength of 200 N/mm.sup.2 to 300 N/mm.sup.2, and a stretchability of less than 35%.

8. The carton according to claim 1, wherein, in the film carrier of the adhesive tape A, the polar nonolefinic polymer is polybutylene terephthalate.

9. The carton according to claim 3, wherein the film carrier of the adhesive tape A and the film carrier of adhesive tape B are identical.

10. The carton according to claim 4, wherein the film of the adhesive tape A has a thickness of 50 to 100 m.

11. The carton according to claim 1, wherein the film of the adhesive tape A has: a machine-direction draw ratio of at least 1:4.5; a machine-direction tensile strength of 200 N/mm.sup.2 to 300 N/mm.sup.2; and a machine-direction stress at 10% strain of at least 80 N/mm.sup.2.

12. The carton according to claim 1, wherein the total width of the adhesive tape B is located centrally with respect to the total width of the adhesive tape A producing a symmetrical construction of the system.

13. The carton according to claim 7, wherein the stretchability of the film carrier of the adhesive tape B is at least 27%.

14. The carton according to claim 13, wherein the stretchability of the film carrier of the adhesive tape B is no more than 30%.

Description

EXAMPLES

Test Methods

(1) The measurements are conducted under test conditions of 231 C. and 505% relative humidity.

Tensile Elongation Behavior

(2) The tensile elongation behavior of the adhesive tape is determined on test specimens (rectangular test strips 100 mm long and 15 mm wide) in accordance with DIN EN 14410:2003 527-3/2/300, with a test velocity of 300 mm/min, a clamped-in length of 100 mm, and a pre-tensioning force of 0.3 N/cm, with specimens being cut to shape with sharp blades for the determination of the data.

(3) Unless indicated otherwise, the tensile elongation behavior is tested in machine direction (MD). The force (tensile strength) is expressed in N/strip width, and the elongation at break in %. The test results, especially the elongation at break (breaking stretch), must be statistically ensured by means of five measurements.

Peel Strength (Bond Strength BS)

(4) For the measurement of the bond strengths, test strips 19 mm wide were adhered without bubbles to a finely abraded (emery paper with FEPA 240 grade abrasive) plate made of stainless steel, and were pressed on using a rubber-clad 2 kg roller, with a speed of 10 m/min. The steel plate and the protruding end of the adhesive tape were then clamped into the ends of a tensile testing machine in such a way as to produce a peel angle of 180. The adhesive tape was peeled from the steel plate at a speed of 300 mm/min. The bond strength is stated in N/cm.

Holding Power (HP; Shear Resistance Time)

(5) The holding power indicates the bonding strength for a loading force acting parallel to the bonded tape. It is the time measured until a loaded adhesive tape shears off completely from a steel plate.

(6) To determine the HP values, a test strip 19 mm wide is adhered to a pretreated steel plaque in such a way as to give a bond area of 1920 mm.sup.2. By means of a clip, a 1 kg weight is suspended from the protruding end of the adhesive tape, thus transmitting a vertical tension force of 5.15 N per 1 cm tape width.

(7) The unit of the holding power is minutes. Where there is a > sign before the values, this means that the measurements were discontinued after this time, since no shearing at all was apparent at that point.

Thickness

(8) This is determined in accordance with DIN 53370.

Raw Materials

(9) Dow 7C06:

(10) PP block copolymer, MFI 1.5 g/10 min, not nucleated, flexural modulus 1280 MPa (Dow Chemical)

(11) Bormod HD 905 CF:

(12) PP homopolymer, MFI 6 g/10 min, flexural modulus 2150 MPa, contains an -nucleating agent (Borealis)

(13) Dowlex 2032:

(14) PE-LLD, MFI 2 g/10 min (Dow Chemical)

(15) Stryon 457:

(16) PS-HI, MFI 3 g/10 min, flexural modulus 2200 MPa (Dow Chemical)

(17) EVAL G156B:

(18) EVAL ethylene content 48 mol %, MFI 6.4 g/10 min, flexural modulus 2800 MPa (EVAL Europe)

(19) Licocene PP MA 7452 GR TP:

(20) PP-g-MA, metallocene polypropylene wax grafted with maleic anhydride (Clariant)

(21) Hostaform C9021 natural:

(22) POM, MFI 8 g/10 min, flexural modulus 2800 MPa (Ticona)

(23) Celanex 2002-2 natural:

(24) PBT, MFI 20, flexural modulus 2500 MPa (Ticona)

(25) Advantageous embodiments of the adhesive tape of the invention are described below by means of examples, without wishing to restrict the invention unnecessarily thereby.

Example 1

(26) The raw materials are compounded and pelletized. The pellets are supplied to a single-screw extrusion system. The film carrier for the adhesive tape A is produced on this single-screw extrusion system, with a flat die having a flexible die lip, in a layer, followed by a chillroll station and a single-stage short-gap drawing system.

(27) Dow 7C06, Celanex 2002-2 natural, and Licocene PP MA 7452 GR TP are mixed in a ratio of 15:4:1 and the mixture is extruded. The die temperature is 230 C. Chillroll temperatures and drawing roll temperatures are set so as to maximize the crystallinity of the film before and after drawing. The draw ratio is 1:5.

(28) Film Properties:

(29) TABLE-US-00001 Tensile strength/N/mm.sup.2 240 Width/mm 25 Elongation at break/% 30 Thickness/m 60

(30) The film is coated on the top face with 0.07 g/m.sup.2 carbamate release, and dried.

(31) The adhesive is mixed in the melt from 42 wt % SIS elastomer, 20 wt % pentaerythritol ester of hydrogenated rosin, 37 wt % a C.sub.5 hydrocarbon resin having an R&B value of 85 C., and 1 wt % Irganox 1010 antioxidant, and the mixture is applied to the underside of the film, at 28 g/m.sup.2 at 150 C. using a nozzle.

(32) A BS to steel of 5 N/cm and a shear strength of greater than 3000 minutes are obtained.

(33) The film carrier of the adhesive tape B is a MOPP film.

(34) Film Properties:

(35) TABLE-US-00002 Tensile strength/N/mm.sup.2 240 Width/mm 4 Elongation at break/% 27 Thickness/m 60

(36) The film is coated on the top face with 0.05 g/m.sup.2 silicone release, and dried.

(37) The adhesive is mixed in the melt from 42 wt % SIS elastomer, 20 wt % pentaerythritol ester of hydrogenated rosin, 37 wt % a C.sub.5 hydrocarbon resin having an R&B value of 85 C., and 1 wt % Irganox 1010 antioxidant, and the mixture is applied to the underside of the film, at 25 g/m.sup.2 at 150 C. using a nozzle.

(38) A BS to steel of 5 N/cm and a shear strength of greater than 3000 minutes are obtained.

(39) The adhesive tapes A and B are applied, as described in accordance with the invention, to a carton composed of a 2.30 double corrugation as per RAL-GZ 492 (DUETSCHES INSTITUT FOR GTESICHERUNG UND KENNZEICHNUNG E.V.).

(40) Tearing the carton open produces a clean edge and only a slight deterioration to the outer liner.

Example 2

(41) The film carrier for the adhesive tape A from example 1 is used, but with a width of 15 mm.

(42) Film Properties:

(43) TABLE-US-00003 Tensile strength/N/mm.sup.2 240 Width/mm 15 Elongation at break/% 30 Thickness/m 60

(44) The film carrier of the adhesive tape B is a MOPP film.

(45) Film Properties:

(46) TABLE-US-00004 Tensile strength/N/mm.sup.2 260 Width/mm 6 Elongation at break/% 30 Thickness/m 85

(47) The film is coated on the top face with 0.05 g/m.sup.2 silicone release, and dried.

(48) The adhesive is mixed in the melt from 42 wt % SIS elastomer, 20 wt % pentaerythritol ester of hydrogenated rosin, 37 wt % a C.sub.5 hydrocarbon resin having an R&B value of 85 C., and 1 wt % Irganox 1010 antioxidant, and the mixture is applied to the underside of the film, at 26 g/m.sup.2 at 150 C. using a nozzle.

(49) A BS to steel of 5 N/cm and a shear strength of greater than 3000 minutes are obtained.

(50) The adhesive tapes A and B are applied, as described in accordance with the invention, to a carton composed of a 1.40 single corrugation as per RAL-GZ 492 (DUETSCHES INSTITUT FOR GTESICHERUNG UND KENNZEICHNUNG E.V.).

(51) Tearing the carton open produces a clean edge and only a slight deterioration to the outer liner.