Adhesive tape and its use

1. Adhesive tape suitable for flying splice of flat web materials having non-polar surfaces, which flat web materials have been wound to form rolls,

the adhesive tape comprising an upper self-adhesive composition, a splittable carrier and a lower self-adhesive composition on a bottom face of the splittable carrier,

wherein

the upper self-adhesive composition is a silicone-free self-adhesive composition that has a bond strength to a polyethylene substrate of 1.5 N/cm or more (measurement method tesa test A) and an initial tack corresponding to a rolling distance of 50 mm or less (measurement method tesa test D),

and the lower self-adhesive composition is a self-adhesive composition that has a bond strength to a polyethylene substrate of 1.5 N/cm or more (measurement method tesa test A) and a complex viscosity of 10 000 Pa·s or more at 1 rad/s and 40° C. (measurement method tesa test F).

2. Adhesive tape according to claim 1 , wherein the upper self-adhesive composition and/or the lower self-adhesive composition is a self-adhesive composition that has a bond strength to a polyethylene substrate of 3.0 N/cm or more (measurement method tesa test A).

3. The adhesive tape of claim 2 , wherein said bond strength is 5.0 N/cm or more.

4. Adhesive tape according to claim 1 , wherein the upper self-adhesive composition is a self-adhesive composition that has an initial tack corresponding to a rolling distance of 40 mm or less (measurement method tesa test D).

5. The adhesive tape of claim 4 , wherein said initial tack corresponds to a rolling distance of 20 mm or less.

6. Adhesive tape according to claim 1 , wherein the lower self-adhesive composition is a self-adhesive composition that has a complex viscosity of 12 000 Pa·s or more (measurement method tesa test F).

7. Adhesive tape according to claim 1 , wherein the upper self-adhesive composition is a synthetic rubber composition.

8. Adhesive tape according to claim 7 , wherein the synthetic rubber composition comprises 45% by weight of a styrene-isoprene-styrene block copolymer, 39% by weight of a rosin ester, 15% by weight of a liquid hydrocarbon resin, 0.5% by weight of a primary antioxidant and 0.5% by weight of a secondary antioxidant.

9. Adhesive tape according to claim 1 , wherein the upper self-adhesive composition is a self-adhesive composition based on block copolymers.

10. Adhesive tape according to claim 9 , wherein the upper self-adhesive composition is a self-adhesive composition based on a mixture of two or more styrene block copolymers comprising at least one diblock copolymer with one of the blocks based on styrene.

11. Adhesive tape according to claim 10 , wherein the upper self-adhesive composition comprises a styrene fraction that is at least 25% by weight and/or a diblock fraction that is at least 40% by weight, based on the total amount of block copolymer.

12. The adhesive tape of claim 11 , wherein said styrene fraction is at least 30% and said diblock fraction is at least 60% by weight.

13. Adhesive tape according to claim 1 , wherein the lower self-adhesive composition is a resin-modified acrylate adhesive.

14. Adhesive tape according to claim 13 , wherein the resin-modified self-adhesive composition is a self-adhesive composition comprising 70% to 80% by weight of acrylate adhesive and 20% to 30% by weight of tackifier resin.

15. Adhesive tape according to claim 14 , wherein the tackifier resin is a terpene phenolic resin and/or the acrylate adhesive is a copolymer of 48.5% by weight n-butyl acrylate, 48.5% by weight 2-ethylhexyl acrylate, 2% by weight glycidyl methacrylate and 1% by weight acrylic acid.

16. Adhesive tape according to claim 1 , further comprising a non-splittable carrier, a top face of the non-splittable carrier being coated with the upper self-adhesive composition, and at least one part of the bottom face of the non-splittable carrier being drawn into the top face of the splittable carrier.

17. Adhesive tape according to claim 16 , further comprising a joining self-adhesive composition that joins the at least one part of the bottom face of the non-splittable carrier to the top face of the splittable carrier.

18. Adhesive tape according to claim 1 , wherein the upper self-adhesive composition and/or the lower self-adhesive composition is a self-adhesive composition that has a complex viscosity of 15 000 Pa·s or more (measurement method tesa test F).

19. A method for bonding flat web materials having non-polar surfaces, which flat web materials been wound to form rolls, in the course of a flying splice, said method comprising bonding said materials with the adhesive tape of claim 1 during the course of said flying splice.

20. A splicing method for performing a flying splice of non-polar flat web materials that have been wound to form rolls, said method comprising adhering the adhesive tape according to claim 1 at least partially behind an end of a topmost web of a new roll or a non-polar flat web material, while bonding a bottom face of the adhesive tape to an underneath web of the new roll and thereby securing it, and placing the new roll thus equipped adjacent to an almost entirely unwound unwinding roll that requires replacement, and accelerating the new roll to the same superficial speed as the unwinding roll, and then pressing the new roll against the topmost web of the unwinding roll, bonding an exposed self-adhesive composition of the adhesive tape to the unwinding web when the webs have substantially the same speeds, while at the same time splitting the splittable system, and non-adhesively masking the self-adhesive compositions of the splittable system with split remnants of the splittable carrier.