Patent Application
20080081186
The adhesive tape further comprises a release system 6 for the non-adhesive masking of the upper self-adhesive composition 1, so that the adhesive top face of the adhesive tape is protected in storage. As the release system it is possible to use all conventional release papers, siliconized release papers for instance, or siliconized release films. The release system may be configured here in one part or in a plurality of parts (not shown in
The embodiment shown in
In order to illustrate the second embodiment of the adhesive tape of the invention, a specific design is set out below by way of example:
An inventive adhesive tape having a width of 50 mm was produced from a machine-finished base paper having a basis weight of 54 g/cm2 and a thickness of 66 μm, as non-splittable carrier 14. The top face of the non-splittable carrier 14 is coated with an upper self-adhesive composition 11.
The upper self-adhesive composition 11 used was a synthetic rubber based on styrene block copolymer, its composition being as follows: 48% by weight of a styrene-butadiene-styrene block copolymer (Kraton D1118 from Kraton), 24% by weight of an alpha-pinene resin (Dercolyte A 115 from DRT, softening point 115° C.), 27% by weight of a liquid hydrocarbon resin (Wingtack 10 from Goodyear—liquid synthetic aliphatic C-5 polyterpene/hydrocarbon resin; softening point 10° C.), 0.5% by weight of a primary antioxidant (Irganox 1010 from Ciba) and 0.5% by weight of a secondary antioxidant (Weston 339 from Interorgano).
The adhesive tape further comprises the splittable carrier 12 and also a lower self-adhesive composition 13 and a joining self-adhesive composition 15. The splittable carrier 12 used was a paper having a basis weight of 51 g/cm2 and a thickness of 90 μm. The width of the splittable carrier 12 was 12 mm.
In addition the adhesive tape has a two-part release system 16 for the non-adhesive masking of the upper self-adhesive composition 11, so that the adhesive top face is protected during storage of the inventive adhesive tape. This release system 16 was produced from siliconized release paper and comprises a back masking part 16a, which masks the part of the adhesive tape that is joined to the topmost ply of the web of the new roll, and a front masking part 16b, which masks the part of the adhesive tape that is joined to the web of the old roll. Both masking parts are separated from one another by a slit which runs in the longitudinal direction of the adhesive tape.
As the lower self-adhesive composition 13 and joining self-adhesive composition 15, identical self-adhesive compositions were used, their composition being as follows: 75% by weight of an acrylate-based polymer (as acrylate adhesive) and 25% by weight of a terpene phenolic resin (as tackifier resin).
The terpene phenolic resin used was the product DT110 from DRT. The acrylate-based polymer used was 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. This polymer had a mass-average molar mass of 950,000 g/mol and a polydispersity D of 8.7 (determined from the results of gel permeation chromatography on 100 μl of sample which had been subjected to clarifying filtration (containing 150 μg of copolymer in solution in tetrahydrofuran), using tetrahydrofuran as eluent (0.5 ml/min), a preliminary column (PSS SDV 10 μm, ID 8*50 mm) and a separating column (PSS SDV 10 μm linear one, 1 D 8*300 mm) from the company Polymer Standards Service, and a differential refractometer (Shodex R171) for detection; calibration with narrow-distribution polystyrene standard (PSS Ready Cals; Polymer Standards Service); conversion of the polystyrene calibration into a polymethyl methacrylate calibration using the Mark-Houwink coefficients for polystyrene (K=0.0136; a=0.7140) and polymethyl methacrylate (K=0.0126; a=0.6880)). For the purpose of crosslinking, 0.3% by weight of zinc chloride, as a Lewis acid, was added to the mixture, based on the dry mass of the copolymer, and the mixture was dried at 120° C. for 15 minutes.
First of all the technical adhesive properties of the upper self-adhesive composition 11 and of the lower self-adhesive composition 13, and also of the joining self-adhesive composition 15, were investigated, by determining the bond strength of the self-adhesive compositions to a polyethylene substrate (measurement method tesa test A), by determining their initial tack on the basis of the rolling-ball tack (measurement method tesa test D), and by determining their complex viscosities (measurement method tesa test F).
Also investigated were the technical adhesive properties of the adhesive tape produced using the self-adhesive compositions 11, 13 and 15. For this purpose, on the one hand, the shear strength of the adhesive tape was determined on a polyethylene backing in the form of the holding power (tesa test B). For this purpose a strip of the adhesive tape with a width of 13 mm and a length of 20 mm was applied to a polyethylene test sheet, which had been cleaned with ethanol beforehand, and was pressed onto the carrier four times with a constant applied pressure. The adhesive tape was loaded with 1 kg at room temperature and the holding power (in minutes) was determined as an average value from three measurements.
In addition, the relative splitting behaviour of a splittable carrier coated on both sides with the respective self-adhesive compositions was investigated (tesa test C). The comparison value used for this purpose was the splitting behaviour of a splittable carrier which had not been coated with self-adhesive compositions. For measurement, strips of the coated and non-coated carrier 12 cm long were first stored under load (2 kg/cm2) at 40° C. for 24 hours. For the purpose of measurement, the carriers were initially split to a length of 2 cm and a measurement was made of the force required in each case to continue to split the carriers with a splitting speed of 300 mm/min. A pass was scored in the test if the difference in force required for continued splitting between the coated and the non-coated carrier was less than 20%.
The results of the investigations are reproduced in Table 1 with reference to the respective test method (tesa test) for the upper self-adhesive composition 11, on the one hand, and for the lower self-adhesive composition 13/joining self-adhesive composition 15, on the other.
A number of further inventive adhesive tapes were produced by a method analogous to that of Example 1 and subjected to measurement, the upper adhesive in these tapes being based on the following compositions (overall composition of the adhesive: 99% base adhesive, 0.5% by weight primary antioxidant (Irganox 1010 from Ciba) and 0.5% by weight secondary antioxidant (Weston 339 from Interorgana), corresponding to Example 1). In this regard, compare Table 2.
The use of adhesive tapes produced in this way for the flying splice of polyethylene films with a thickness of 35 μm to 60 μm was successful in practical testing.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2006 008 561.2 | Feb 2006 | DE | national |
| 10 2006 053 439.5 | Nov 2006 | DE | national |
