Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2000-07-17
2003-09-30
Crispino, Richard (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S289000, C156S324000, C428S352000, C428S354000
Reexamination Certificate
active
06627023
ABSTRACT:
The invention relates to the use of specific pressure-sensitive adhesive (PSA) tapes for flying splice (flying reel change) as practised, for example, in paper converting machines or printing machines with paper webs or the like.
This technique enables splicing to be carried out on reel change without stopping the machine. In a simplified description, the reel to be newly inserted is provided at its leading edge with a pressure-sensitively adhering area which, after the reel has been accelerated to the web speed of the machine, is brought adjacent to the end of the web of the expiring reel and bonded to it, as a result of which the leading edge of the replacement reel is drawn by the expiring web into the machine. The PSA areas required are produced using pressure-sensitive adhesive tapes. In the case of flying splice, these tapes are either double-sidedly pressure-sensitively adhering tapes, with which the webs are bonded in an overlapping formation (web over web), or else, in many cases, are splicing tapes (end to end) of sufficient width which adhere pressure-sensitively on one side.
Although the principle has become established in practice for decades, its technical implementation has had to be continually adapted to the increased web speeds and web widths of the machines. Thus within three decades web speeds have been increased from approximately 600 m/min to the present-day levels of up to 2500 m/min, and machine widths from approximately 2 m to approximately 8 m nowadays. The associated, relatively high forces which act on the splices mean that, even with a somewhat reduced web speed during the splicing operation, it is necessary to improve the adhesive compositions and to prepare the splice in a carefully worked-out manner. A machine stoppage due to web breakage at such speeds and web widths is the cause of very high costs of loss (outage time and reject product during the start-up phase).
A particularly large amount of time and care in preparing the splice is required to fix the leading edge to the replacement reel. Prior to splicing, indeed, it is necessary to bring the new reel to a peripheral speed which corresponds approximately to the web speed. For this operation it is necessary for the leading edge, which carries the PSA area applied for splicing, to adhere firmly to the surface of the reel by means of fixing aids. At the high speeds, even slight fluttering of this web surface hinders full-area bonding to the expiring web, and leads to breakage. As soon as the bond has been produced, on the other hand, fixing aids must be detached in order that the leading edge can separate from the reel surface. Pressure-sensitively adhering paper labels, for example, are used as such fixing aids, these labels possessing a more or less defined tensile strength as a result of choice of the paper and/or by means of specific geometry, and being stuck onto the reel by hand, in a defined number, so that the leading edge is fixed to the underlying area of the following turn of the reel. Immediately after the splicing of the two webs, the fixing aids are torn apart by the web tension.
For reliable splice preparation, and to avoid the time-consuming and not always reliable manual fixing, pressure-sensitively adhering splicing tapes have been developed which comprise in integrated form not only the adhesive areas provided for splicing but also the fixing aid for the leading edge. Divided up in the longitudinal direction, these adhesive tapes possess on their backing material two striplike zones, one zone being double-sidedly or single-sidedly pressure-sensitively adhering for the splicing operation and being stuck onto (in the case of double-sided pressure-sensitive adhesion) or in part under (in the case of single-sided pressure-sensitive adhesion) the leading edge of the replacement reel. The second, likewise pressure-sensitive adhesive zone, which is arranged on the adhesive tape adjacent to the first zone, at a greater or lesser distance from it, serves, by means of its adhesive area lying on the underside of the adhesive tape, for fixing to the following turn which is formed by the reel surface.
WO 95/29115 describes a splicing tape where the integrated fixing aid is fastened to the reel surface by means of a weakly adhering, reversibly adhering adhesive composition. The reversibly adhering coating is intended to ensure that during the splicing operation the fixture is detached readily and without leaving sticky residues on the reel surface. This procedure has not become established in practice, since the strength levels of the reversible bond are dependent on the nature of the type of paper to be converted and hence are not constant. Furthermore, the PSA area of the fixing aid remains uncovered on the underside of the paper web and, during the converting process, is passed over the hot drying cylinders of the paper machine, depositing sticky particles which contaminate the paper, soil the drying felts and wires, and if allowed to accumulate substantially may cause breaks by causing the web to stick to drying cylinders.
Similarly, in DE 40 33 900, web fixing is carried out with a weakly pressure-sensitively adhering section in conjunction with the splicing zone.
0 418 527 A2 describes a splicing method especially for flying reel change in a printing machine. Here, the integrated, pressure-sensitively adhering fixing aid is separated from the splice zone, following the bonding of the webs, by means of an incorporated predetermined breakage point. The predetermined breakage point used is a longitudinal perforation of the backing material in the adhesive tape between the pressure-sensitive adhesive films for the splice zone and fixing zone. An advantage with this method is that the pressure-sensitively adhering areas remain covered, after splicing, by non-adhesive substrates and, consequently, no sticky surfaces are passed through the printing machine or the like. A disadvantage, on the other hand, is the poorly defined breaking strength of the predetermined breakage point in the form of a perforation. The fluctuations in strength in this case may be considerable. Moreover, separation via the individual perforations takes place jerkily in the manner of a touch-and-close fastener. Because of the individual tensile strength peaks which occur in this case, it is possible, even with small weaknesses of the individual perforation interstices, for the entire assembly to tear prematurely in a manner of a touch-and-close fastener. For printing machines with web speeds of around approximately 800 m/min, this principle may be sufficient; with the substantially faster-running paper converting machines, improved solutions to the problem are desirable.
U.S. Pat. No. 5,702,555 describes a method of releasably securing web ends to reel surfaces, release taking place in a defined manner, using a double-sidedly pressure-sensitively adhering tape which comprises, between the pressure-sensitively adhering coatings, a readily cleavable paper backing which acts as a predetermined breakage zone. When the fixture is detached, the pressure-sensitive layers remain on the paper web, with the paper backing positioned between them cleaving more or less centrally and so breaking the bond between the leading edge and the underlying turn of the reel. In this case, the pressure-sensitive adhesive layers remain covered by the two relatively thin paper webs formed in the cleavage, so that no sticky areas are passed through the machine.
DE 196 28 317 A 1 and DE 196 32 689 A1 describe pressure-sensitive adhesive tapes constructed especially for flying splice in high-speed paper machines and comprising particularly readily cleaving paper as intermediate backing material for an integrated fixing aid of the leading edge.
WO 99/46196 describes, inter alia, a repulpable splicing tape with an integrated fixing aid, the multi-ply fixing aid comprising incorporated therein a water-soluble polymer layer in contact with a silicone or organofluorine-compound release layer as a predetermined breakage point. The cleavage force is
Gleichenhagen Peter
Müller Annemarie
Chan Sing P.
Crispino Richard
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