Description:

The invention pertains to a system for handling winding reels that comprises a cantilever expansion shaft with an integrated axial sliding mechanism and a retractable shaft-end support Expansion shafts (also known as expansion axis) are widely used for handling winding reels in the processing of web-fed materials as for example is common in the coating, laminating and printing industry.

The expansion shaft is usually fitted into a core onto which film like materials (such as paper, plastic film, metal foils, etc.) are wound. The core onto which film like material is wound is also referred to as a reel. An expansion shaft is designed such that it can be slid into the core of the reel and expanded to fix to the core onto the shaft. The expansion shaft can also be contracted such that the shaft may be removed from the core. The expansion shaft makes it possible to grip the core without damage and at the same time it provides an interface for

handling/controlling the core and web via motors and brakes.

The expansion/contracting mechanism in the expansion shaft is normally driven pneumatically or mechanically. A pneumatic expansion shaft may also be referred to as an air expanding shaft or airshaft. A pneumatic expansion shaft tightens to the core by filling the shaft with compressed air. Although multiple designs exist, a pneumatic expansion shaft typically contains one or more air inflatable

compartments that upon inflation press against lugs. The lugs are pressed outwards and grip into the inside of the core. The pneumatic system makes it relatively simple to use this type of shaft. However, the weight of the shaft and/or core (with film like material) might cause the shaft to clamp to the core in a non- concentric way. To overcome this problem DE 91 13939 U1 teaches the use of spring loaded balls which are placed partially sunk into the surface of the expansion shaft. The spring balls facility concentric positioning of the expansion shaft into the core. Also, the applied gripping force that can be applied using pneumatic systems is limited when compared to the mechanical expansion shaft. A mechanical expansion shaft works on similar principles as the pneumatic version, however, the outward motion of the lugs is driven by a mechanical movement such as turning a screw. This type of shaft has the advantage of a more concentric clamping and high gripping force.

Expansion shafts are usually inserted into the core or reel. The expansion shaft, including the core/reel, is then positioned on both sides into bearings. However, in some cases the core or reel is slid over the expansion shaft instead of the expansion shaft inserted into the core or reel. The expansion shaft is on one side (permanently) fixed and the other side is free such that the core or reel can slid over the shaft. This design is known as a cantilever expansion shaft and is particularly useful when handling cores/reels that are relatively narrow and low weight. Common cantilever expansion shafts thus have therefore normally a length of <0.6 meters. An example of a cantilever shaft is given in

JP 2012153438. The document teaches a shaft that allows easy positioning of a reel onto said shaft, but also prevents idle turning of the reels upon

winding/unwinding. Hereto rollers are fixed to a spring leaf positioned on the outer surface of said shaft. The spring leaf is pressed inwards when a reel is positioned on the shaft. The spring-loaded rollers now allow easy movement of the reel in the axial direction of the shaft, but at the same time prevent movement in the tangential direction. This system is useful for small and light weight reels.

For larger rolls the friction between the shaft and reel is a known problem. For example, US 2005/150996 teaches the use of a fluid cushion between a shaft and reel to reduce friction between the reel and shaft. Reduced friction at the shaft/reel interface lowers the forces required to separate reels from the shaft. Lower separation forces should mean less damage to the wound web material and less wear and tear on the shaft and extraction equipment. To avoid friction in large/heavy reels, the expansion shaft (being the lighter component of the two) is usually inserted into the reel rather than vice versa. It is one objective of this invention to provide expansion shafts that are capable to also handle cores/reels of greater width and/or weight. More in particular the invention is related to provide cantilever expansion shafts that are useful for a process wherein a continuous process for making coated adhesive tapes is described comprising the steps of dosing a polymerizable mixture containing mono ethylenically unsaturated monomers and/or oligomers on a carrier foil, guiding the mixture on the carrier foil through a UV-light curing zone to initiate the polymerization and forming the adhesive tapes, releasing the carrier foil and taking up the adhesive tapes, which process sets forth that a dry coating film is positioned between the carrier foil and the polymerizable mixture to form the coated pressure sensitive adhesive tape.

Such a process is e.g. disclosed in EP 0 259 094 A2, US 4 894 259 and in EP 2 147 025 B1 and may essentially be described as follows:

A polymerizable mixture containing mono ethylenically unsaturated monomer and/or oligomers is dosed on a carrier foil. The polymerizable mixture might also contain non-polymeric fillers and additives such as hollow glass/plastic spheres, fumed silica, talc, aluminum trihydrate, quartz powder, etc.

The dry coating does not contain any significant amount of carrier fluid such as solvents or water. Small amounts of residual carrier fluids (typically no more than 10%, preferably even less than 2% and most preferably 0%) might be present in the coating material since the coating materials can be applied to a carrier foil via wet processing. The residual carrier fluids might be left in the coating even after removal (e.g. evaporation) of the carrier fluids. These carrier fluids typically have viscosity of less than 25 mPas and most of them have a viscosity which is even below 5 mPas. A carrier fluid is a fluid that is used to modify the viscosity of a coating formulation such that the coating materials can be processed via wet processing. A dry coating is obtained by extracting the carrier fluid from the coating via evaporation. Examples of typical carrier fluids are water and solvents such as acetone, acetonitrile, benzene, butanol, carbon tetrachloride, chloroform, cyclohexane, 1 ,2- dichloroethane, dichloromethane, dimethyl formamide, dimethyl sulfoxide, dioxane, ethanol, ethyl acetate, ethyl ether, heptane, hexane, Isopropyl alcohol, methanol, methyl-t-butyl ether, methyl ethyl ketone, pentane,

tetrahydrofuran, toluene, and xylene. The viscosity of the carrier fluids is measured at 20 °C with an Ostwald

viscometer.

The coating material is preferably a polymeric material with adhesive properties. It can for example be based on a thermoplastic hot melt adhesive such as Ethylene- vinyl acetate (EVA), Ethylene-acrylate copolymers, Polyolefins (PO), Polyamides (PA) and polyesters, Polyurethanes (PU) and Styrene block copolymers. The coating material can also be a pressure sensitive adhesive (PSA). PSA's are typically based on elastomeric polymers (often compounded with tackifiers) that are based on acrylics, butyl rubber, ethylene-vinyl acetate (EVA), natural rubber, nitriles, silicone rubbers and styrene block copolymers. The coating material can be based on materials that have a glass transition temperature. The coating material can consist of a viscous material, in case the coating material is a polymer, which is not cross-linked and which has a glass transition temperature below room temperature. Although the coating material might be a viscous material, it does not mean that it is wet material since it does not contain any carrier fluid such as solvents or water. Preferably, the viscosity of such a viscous coating material is higher than 2 Pas, even more preferably it is higher than 10 Pas.

The dry coating is a layer that comprises a polymerizable mixture containing mono ethylenically unsaturated monomers and/or oligomers. Thus, two layers of polymerizable mixtures are formed on top of each other. Each mixture can be designed differently and, after UV curing, each layer may have different adhesive (and cohesive) properties. The resulting product - although comprising two layers - would still form one single tape which just has a two-layer-structure. By doing so, one would be able to create a tape which has on each side a different

adhesive/cohesive property. For example, one would be able to make a tape which is ideal for bonding two totally different substrates like a metal with a plastic. One layer is designed for adhesion to metal; the other layer is designed for adhesion to plastic. From a production point of view one could dose the first polymerizable mixture, if needed (partially) UV cure the mixture, and then apply the second polymerizable mixture. If the first polymerizable mixture is not sufficiently hardened or sufficiently viscous, the two layers with polymerizable mixtures could mix and form one more or less homogenous composition. The viscosity of suitable monomers would be within the range of < 25mPas.

However, these materials are excluded from the list of carrier fluids since these compounds are not extracted via evaporation from a coating to obtain a dry coating. Instead these materials can polymerize into a dry coating. Monomers are therefore not considered a carrier fluid. Monomers do not "carry" the dry coating; instead they form the dry coating.

To this end the dry coating comprises or is made of essentially the same

components as mentioned above for the backing material.

The UV-light zone is preferably based on low intensity UV light (<20 mW/cm2) with a wavelength that is predominantly between 320-400 nm. The UV-light zone consists of multiple UV lamps that might be located on one side of the carrier foil on which the polymerizable mixture of mono ethylenically unsaturated monomers and/or oligomers is dosed. Preferably, the UV-light zone consists of multiple UV lamps that are located on both sides of the carrier foil on which the polymerizable mixture of mono ethylenically unsaturated monomers and/or oligomers is dosed. The releasing carrier foil is preferably based on a bi-axially oriented p-polyethylene terephthalate (BO-PET). Even more preferably the surfaces of the BO-PET are siliconized and most preferably the surfaces are differential siliconized. In the latter case the release value of the silicon layer on both surfaces of the BO-PET is different. It should be mentioned that the siliconization on the carrier foil is not a dry coating as claimed in the invention since it does not adhere to the

polymerizable mixture after polymerization of said mixture in the UV-zone. In contrary, the siliconization aims to facilitate easy release of the polymerized mixture after polymerization and will not adhere to it. Preferably a second foil is used to cover the polymerizable mixture of mono ethylenically unsaturated monomers and/or oligomers. By sandwiching the polymerizable mixture between the carrier foil and a second foil it is avoided that oxygen can inhibit the polymerization reaction by which the polymerizable mixture is hardened in the UV-zone. The second foil is preferably based on a bi-axially oriented p Polyethylene terephthalate (BO-PET). Even more preferably the surfaces of the BO-PET are siliconized and most preferably the surfaces are differential siliconized. In the latter case the release value of the silicon layer on both surfaces of the BO-PET is different.

The process can be carried out on equipment as further elucidated by Fig. 5 and 6. Such an equipment comprises as components a dispenser for dosing a polymerizable mixture on a carrier foil, a roller-knife-coater, one or more means for supplying and retrieving carrier foils, second foils and/or protection foils, a UV-light curing system, a means for taking up the tapes and a means for transporting the polymerizable mixture on the carrier foil form the dispenser to the taking-up means. In particular, during such a process, it is necessary to slide reels of carrier foils and cores over a cantilever expansion shaft.

Cantilever expansion shafts are particularly useful for this process since an equipment, as shown in Fig. 5 and 6, allows minimal space for handling cores, reels and expansion shafts. In particular, the siliconized bi-axially oriented polyethylene terephthalate (BOPET) production liners applied in a process as mentioned above need to be handled carefully. The layers of siliconized BOPET can easily slip due to the low friction between the layers of siliconized BOPET. When mechanical force is applied to the side of a roll of siliconized BOPET (as for example is done when the roll of siliconized BOPET is placed over a cantilever expansion shaft), layers of siliconized BOPET can easily slip causing a distorted roll of siliconized BOPET to be placed on the cantilever expansion shaft. Besides problems from a production point of view, this also causes dangerous situations when the roll of siliconized BOPET is placed on the cantilever expansion shaft. This invention aims to overcome the restrictions of known cantilever expansion shaft designs and in particular when handling wide and/or heavy reels with low friction material such as siliconized BOPET.

This is achieved by providing a system for handling winding reels that comprises a cantilever expansion shaft with an integrated axial sliding mechanism and a retractable shaft-end support and which is further characterized by that said axial sliding mechanism is based on at least three rollers that are partially sunk into the cantilever expansion shaft and which are distributed at equal distance around said shafts circumference.

The invention is exemplified by Fig. 1 a. Here a cantilever expansion shaft (1 ) is shown which comprises rollers (2) which rollers rotate in axial direction to allow a reel or a core to easily be moved onto the shaft. In Fig. 1 b represents a schematic drawing of the cross-section of the cantilever expansion shaft (1 ) shown in Fig. 1 a. In Fig. 1 a and Fig. 1 b three sets of three rollers (2) that are partially sunk into the cantilever expansion shaft (1 ) and which are distributed at equal distance (d1 , d2 and d3) around said shafts circumference. The numbers of rollers or sets of rollers are not limited and can be chosen to best fit the purpose. It is sufficient and also preferred that the rollers only slightly project over the surface of the shaft to serve the purpose. A roller can be any object than can be rotated around a central axis and which has a projected circular circumference when viewed parallel to said central axis. Said central axis can be an actual physical axis around which a roller rotates as well as an imaginary axis. Preferentially said roller is based on a cylindrical shape with a narrow height and which can rotate around the central cylinder axis. But also, a spherical or ball like shape could be possible.

The rolls or balls can be made of steel, essentially of the same material as the shaft itself. Also, other materials are possible, such as ceramics or plastics, as e.g. polyethylene, nylon, polytetrafluorethylene and so on. A shaft according to the invention typically has a rod or pole like shape. The cross- section of the shaft can have any shape, but it is preferably ellipsoidal, rectangular, square, pentagonal, hexagonal, heptagonal, octagonal, nonagonal or decagonal. Most preferably the shape is circular.

The cantilever expansion axle comprises lugs which can be pressed outwards or move inwards to hold/release the core of a winding reel. The lugs can have any shape or size such as bars or pins. In the expanded state the lugs prevent the winding reel from moving. Therefore, the distance between the central axis of the cantilever expansion shaft and the outmost parts of the lugs is larger than the distance between the central axis of the cantilever expansion shaft and the outmost parts of the rollers, when the lugs are pushed outwards and said distance is smaller when the lugs are pressed inwards. If this requirement is not fulfilled, then the reel is not fixed and it can still be moved with relative ease. The absolute value to which the distance is smaller or larger is less relevant and would depend on the required force to fix the reel and diameter of the cantilever expansion shaft. A winding reel is a roll shaped object and which comprises material which have been wound around a central core. In particular, to invention relates to winding reels that are based on materials such as paper, plastic film and metal foils. Such materials are particular sensitive to axial forces because friction between layers of material can be very low. The retractable shaft-end support supports the end of the cantilever expansion shaft according to the invention when a winding reel is being wound/unwound. The tension on the web and/or the weight of the reel itself can cause the cantilever expansion shaft to deflect which can in turn result in severe web tension problems. The retractable shaft-end support prevents deflection of the cantilever expansion shaft, but at the same time it can be easily retracted when mounting/demounting of a winding reel is required.

The cantilever expansion shaft might contain a bearing at the shaft-end of said shaft. Said bearing can be placed into the retractable shaft-end support and its position can be fixed by a clamping mechanism which is part of the retractable shaft-end support. The bearing allows the shaft-end to be supported with very little frictional losses.

Alternatively, the retractable shaft-end support might contain a bearing in which the shaft-end of the cantilever expansion shaft can be placed. Preferably, the bearing consists of at least two parts that can be opened by moving the parts away from each other and closed by moving the parts toward each other. In the closed state the parts form a bearing around the shaft-end. The retractable shaft- end support might also further contain a locking mechanism which can be used to lock the position of the parts of which the bearing comprises. The invention also pertains to apparatuses which contain a system for handling winding reels that comprises a cantilever expansion shaft with an integrated axial sliding mechanism and a retractable shaft-end support and which is further characterized by that said axial sliding mechanism is based on at least three rollers that are partially sunk into the cantilever expansion shaft and which are distributed at equal distance around said shafts circumference. . Such

apparatuses can be many types of equipment and in particular web handling equipment. One such apparatus is for example described below with regard to Fig. 5 and 6. Fig. 1 further shows a lug 3, which can be pressed against the reel or the core in order to better fixate it to the shaft.

Fig. 2 shows an inventive cantilever expansion shaft (1 ) in operation having a roll with siliconized BOPET on it. The rollers (2) can be seen partially. The lugs cannot be seen.

Fig. 3 a, shows schematically the technical details of an inventive cantilever shaft (1 ) with the rollers (2), the lugs (3). In Fig. 3b the retractable shaft-end support (4) is shown in a retracted state and in Fig 3c the retractable shaft-end support is shown in a supporting state Fig. 4 shows schematically the inventive cantilever shaft in operation carrying a roll located on the shaft.

A process and an equipment for which the inventive cantilever shaft is suitable are further elucidated by reference to the Fig. 5 and 6. The rolls in the process and in the equipment elucidated by Fig. 5 and 6 are preferably located on cantilever shafts according to the present invention.

Fig. 5 is a schematic representation of a continuous process for making coated adhesive tapes according to the invention. The polymerizable mixture is kept in a container from which it is pumped to the roller-knife-coating system. Here the mixture is dosed on a carrier foil that contains a dry coating and said coating being positioned on the side of the carrier foil on which the polymerizable mixture is dosed. The carrier foil, dry coating and polymerizable mixture are transfer into a UV light zone. The UV light initiates the polymerization reaction of the

polymerizable mixture. After hardening of the polymerizable mixture the dry coating adheres to the hardened mixture, forming a coated adhesive tape. The carrier foil and/or second foil can be removed prior to winding the coated adhesive tape into a roll. It is also possible to apply an addition release liner to the coated adhesive tape prior to winding it into a roll. Fig. 6 is a further schematic representation of a continuous process for making coated adhesive tapes according to the invention. The polymerizable mixture is kept in a container from which it is pumped to the roller-knife-coating system. Here the mixture is dosed on a siliconized BOPET carrier foil that contains a dry coating and said coating being positioned on the side of the carrier foil on which the polymerizable mixture is dosed. A second siliconized BOPET foil that contains a dry coating (said coating being positioned on the side of the carrier foil that faces the polymerizable mixture) is applied to the polymerizable mixture. The carrier foil, second foil dry coatings and polymerizable mixture are transfer into a UV light zone. The UV light initiates the polymerization reaction of the polymerizable mixture. After hardening of the polymerizable mixture, the dry coatings adhere to the hardened mixture, forming a coated adhesive tape. The carrier foil and/or second foil are removed prior to winding the coated adhesive tape into a roll. It is also possible to apply an addition LDPE release liner to the coated adhesive tape prior to winding it into a roll (marked product)

Fig 7 shows the shaft-end of the cantilever expansion shaft and a bearing (10) which is placed at the end of said shaft. Fig. 7 b shows the retractable support mechanism (1 1 ) which comprises a clamping mechanism (12) which can be placed around bearing (10). Fig. 7 c shows the clamping mechanism (12) closed around bearing (10) and thus keeping the shaft-end of the cantilever expansion shaft in position without causing any significant friction losses.