EP0966395A1

EP0966395A1 - Wound core

Info

Publication number: EP0966395A1
Application number: EP98916882A
Authority: EP
Inventors: Jan Chal; Hans Hazes; Hansjürgen LINDE; Bernd Lühmann; Uwe Neumann; Ralf Schliephacke
Original assignee: Beiersdorf AG
Current assignee: Tesa SE
Priority date: 1997-03-13
Filing date: 1998-03-04
Publication date: 1999-12-29
Anticipated expiration: 2018-03-04
Also published as: EP0966395B1; WO1998040301A1; ATE242169T1; ES2200336T3; DE19710331C2; DE19710331A1; DE59808636D1; US6390411B1

Abstract

Core for winding self-adhesively coated materials in web form, wherein the outer contour of the core is formed by at least one substantially round, self-contained segment, the ends of which run together in an edge, witha) the round segment being shaped convexly with respect to the axis of the core,b) the normals to the surface of the round segment being aligned substantially orthogonally with respect to the axis of the core,c) the edge being aligned substantially parallel with respect to the axis of the core and the core having a recess on the inside, so that the roll together with the core can be fitted on commercially available adhesive tape dispensers which have cylindrical core holders.

Description

description

Winding core

The invention relates to a further development of the known cores of cylindrical shape, which serve as a carrier for a roll of self-adhesive coated, sheet-like materials.

Such winding cores are generally cylindrical, that is to say circular in shape. Typical embodiments include single or double-walled plastic cores or also those made of cardboard. The inner diameters of adhesive tape winding cores are usually adapted to the processing equipment of the self-adhesive tape rolls containing them. Typical inner diameters are, for example, 1 inch, 1, 5 inch, 50 mm or 3 inches. Thickness, shape and inner diameter of the winding cores are oriented u. a. to the requirements for the manufacture and processing of individual rolls. The widths of assembled self-adhesive tape rolls are typically in the range of a few mm up to approx. 200 mm. Usually, the width of the winding cores used corresponds to the width of the adhesive tape wound on them.

Non-cylindrical winding core shapes are used for special self-adhesive tapes. For example, US Pat. No. 5,269,421 ("Package for PSA tape has thin two-ply core with length of PS tape wound around it in layers") describes, for example, a flat, flat, two-layer rectangular core, around which an adhesive tape is wound. One advantage of the adhesive tape wound on the rectangular core is its space-saving (flat) form of assembly.

Because of their round shape, cylindrical winding cores offer numerous advantages over the non-round geometries for the winding and slitting process when processing the adhesive tape nut rolls (jumbos) into small rolls. In particular constant winding forces can be easily adjusted over the entire roll circumference during roll production. Corresponding advantages also apply to the processing of small rolls.

An important quality criterion of self-adhesive tape rolls is their freedom from telescoping and in many cases the absence of air pockets (fish eyes) between adjacent layers of adhesive tape. Telescoped self-adhesive tape rolls can often no longer be processed properly due to the changes in shape and dimensions of the roll and the frequently observed deformation of the adhesive film strip itself. Fish eyes are often undesirable on transparent adhesive tape rolls for aesthetic reasons, since they reduce roll transparency. Often, however, they also cause increased rolling noise when the adhesive tape is cut to length and uneven adhesive forces in the order of magnitude of the fish eyes that occur, and can therefore also cause technical disadvantages.

Furthermore, for example, information applied to the outside of the winding core by, for example, printing or inserting a printed paper, is not or only partially visible despite the use of highly transparent adhesive tapes in individual layers due to the formation of fish eyes. Such cloudy rolls often give consumers the impression of inferior quality. The production of telescopic adhesive tape rolls, which at the same time do not have any fish eyes, is often mutually exclusive or is nevertheless without correspondingly complex technical precautions, as described, for example, in EP 0 670 277 A ("Method of making pressure sensitive adhesive tape rolls with a transparent to the core appearance ") are difficult to achieve in many cases. For example, a fish-eye-free winding can only be achieved with a correspondingly high winding tension or a comparatively high contact pressure when manufacturing small rolls. However, the aforementioned measures consistently increase the risk of subsequently telescoping adhesive tape rolls. This applies in particular to adhesive tape rolls with long assembly lengths and at the same time a small roll width.

Known methods for reducing the tendency to telescope while increasing the winding tension (and thus reducing the frequency of fish eyes) are the use of barrel-shaped winding cores, the use of winding cores, which carry a slight increase in the middle, and the use of slotted ones Cores, as described for example in EP 0 430 548 A ("Collapsible core adhesive rolls").

Significant disadvantages of using the aforementioned cores include that

- Barrel-shaped winding cores and those which carry a slight increase in the center cannot be obtained in a simple manner by separating logs.

- Slotted cores have a lower mechanical stability due to the insertion of the slots.

- When using barrel-shaped winding cores or those with a central elevation, adhesive tape from the winding close to the core is noticeably deformed by the non-cylindrical core surface, which can not only result in an unsightly appearance of the unwound adhesive tape, but also cause a reduction in the technical suitability of the corresponding material can.

Another possibility of reducing the tendency to telescope while increasing the winding tension is to use cores that have a smaller width than the adhesive tape wound on them. This method is disadvantageous in that, depending on the difference in width between the winding core and the adhesive tape, the wound adhesive tape can crimp, which can lead to similar disadvantages as described above.

The object of the invention was to provide a core which does not have the disadvantages of the prior art mentioned, and which is therefore in particular able to wind largely without fish eyes while at the same time reducing the tendency to telescope.

This problem was solved by a core, as described in claim 1. The subclaims relate to advantageous developments of the core according to the invention. Accordingly, the outer contour of the core for winding self-adhesive coated web-shaped materials is formed from at least one essentially round, self-contained segment, the ends of which converge in an edge, a) the round segment being convex to the axis of the core, b) the surface normals of the round segment are aligned essentially orthogonally to the axis of the core, c) the edge is aligned essentially parallel to the axis of the core, and the core has a recess on the inside, so that the roll and core are attached to commercially available adhesive tape assemblies, the one in particular have cylindrical core receptacles, can be used.

In a second embodiment, the outer contour of the core for winding self-adhesive, coated web-shaped materials is formed by at least two essentially circular segment-shaped segments, with a) the segments being arranged convex to the axis of the core, b) the surface normals of the segments orthogonal to the axis of the core are aligned, c) the edges at which the segments meet, are aligned parallel to the axis of the core and the core has a recess on the inside, so that the roll together with the core can be used on commercially available adhesive tape offices, which in particular have a cylindrical core receiver.

Advantageously, the outer contour of the core is formed by two to seven circular segment-shaped segments of the same shape, which are arranged symmetrically about the axis of the core, with a) the segments being arranged convex to the axis of the core, b) the surface normals of the segments orthogonal to the axis of the Core are aligned, c) the edges where the segments meet are aligned parallel to the axis of the core.

When the core according to the invention is viewed from the side, the delimitation of the outer contour edge spans a regular arch triangle to a pentagon. Typical embodiments include curve shapes of the same thickness, such as those based on regular or non-regular Reuleaux polygons. In a particularly preferred embodiment of the core according to the invention, the outer contour is formed by three circular segment-shaped segments of the same shape, which are arranged symmetrically about the axis of the core, again a) the segments being arranged convex to the axis of the core, b) the surface normals of the segments are aligned orthogonally to the axis of the core, c) the edges where the segments meet are aligned parallel to the axis of the core.

When the core according to the invention is viewed from the side, the delimitation of the outer contour edge spans a regular arch triangle.

The edges at which the segments meet are preferably pointed. In a further advantageous embodiment, the edges have a radius of curvature of less than 3 mm, preferably less than 1 mm, very particularly preferably less than 0.6 mm.

The surface normals preferably form an angle between 80 ° and 90 ° with the axis of the core.

The segments preferably have a circular section angle greater than or equal to 30 °.

Furthermore, it is within the inventive concept if the segments have a slightly spherical shape, with the segments preferably having the highest elevation in the center.

Suitable materials for the production of cores according to the invention are the conventional materials which are also used for the production of cylindrical cores, such as numerous plastics which can be pigmented, colored or used in a transparent look. Plastics that can be processed in injection molding, for example polystyrene, are preferably used. Depending on the design of the dispenser used, cores made of stone, ceramic, metal or cardboard can also be used. Suitable adhesive films include those which contain a plastic film carrier which is equipped on one or both sides with a pressure-sensitive adhesive. Suitable plastic films include those based on polyolefins, especially made of polyethylene and polypropylene, polyesters, polyamides, polystyrene, to name just a few. Films can be used unstretched or stretched (monoaxial or biaxial). Film carrier thicknesses are preferably between 12 μm and 100 μm, preferably between 20 μm and 60 μm. Suitable PSAs include, inter alia, those based on natural rubber-resin mixtures, synthetic rubber-resin mixtures, acrylate copolymers and polyolefins.

The materials listed represent only exemplary possibilities. Of course, the inventive concept also includes other materials not mentioned here.

Surprisingly, the cores according to the invention, which differ from the conventional cylindrical shape, have excellent properties. When the cores are used, non-round rolls of adhesive tape are obtained, which are better referred to as adhesive tape winding forms in the further description. These forms of adhesive tape enable a high degree of fish-eye freedom while reducing the tendency to telescope.

In addition, the cores or adhesive tape winding forms according to the invention have further advantages. Upright cores and adhesive tape winding molds offer a more stable stand than rolls in the production and processing area. Furthermore, such adhesive tape winding forms have an appealing design that stands out from the previously known rolls.

Explanations for increasing fish-eye freedom while lowering the tendency to telescope can be found in the following observations:

• The forces causing the telescoping of the adhesive tape rolls are distributed very favorably. A correspondingly positive influence of the pulsating winding tensions / contact pressures which develop in accordance with the core shape used in the production of the adhesive tape winding molds.

In the following, cores according to the invention are to be described by means of several examples, without wishing to restrict the invention unnecessarily.

example 1

Adhesive tape rolls measuring 33 m x 19 mm (the information corresponds to the length times the width of the adhesive tape rolls) were wound by a defined winding tensile force and at the same time pressed on with a rotating rubber roller. The aim was to obtain a transparent roll which, on the one hand, does not telescope after winding due to the winding tension being too high, and on the other hand has no air pockets in the form of small bubbles, the so-called fish eyes.

The following test parameters were chosen:

- web speed = 20 m / min

- winding tension = 1.1 N / cm

- Pressure force of the pressure rollers = 1, 0 + 0.5 N / cm

In a similar way, a 19 mm wide hexagonal core, which laterally presents itself as a regular hexagon, with rounded edges (corners), as well as a curve body similar to 19 mm in width, as shown in Figure 1, consisting of three uniform, symmetrically arranged Circular segments, processed into appropriate adhesive tape winding forms.

The hexagon core had an inner diameter of 26 mm. Its outer diameter was 28 mm between parallel outer boundaries and 30 mm between opposite edges. The edges showed a radius of curvature of 3 mm.

Curve bodies of the same thickness have a constant contour width. The basic shape of the curve body with the same thickness is determined by an isosceles triangle. Uniform thicknesses are usually used in the construction of gears in order to smoothly derive straight-line movements in back and forth or up and down movements.

The geometry of the curve body of the same thickness used could be described as follows: Its basic shape is an equilateral triangle with α = 120 °. When rotating around the center M, a circle with the arc radius r and a so-called stroke distance s are formed. The curve body of the same thickness used for the winding tests had the dimensions listed in the following table (see FIG. 1):

Table 1: Dimensions of the curve body of similar thickness used

All forms of adhesive tape were stored for 48 hours at a temperature of 40 ° C, then examined for fish eye-containing and telescopic goods. 50 adhesive tape winding bodies per winding form were evaluated. The following results were obtained:

Table 2: Results of the test series

Example 2

In order to demonstrate the explanations of why the curve body of the same thickness enables a roll winding that is free of telescoping and fish eye-free, a curve body consisting of two segments (arched triangle) with α = 180 ° was tested as the roll core in a second series of experiments.

The following test parameters were chosen:

- web speed = 20 m / min

- winding tension = 1.1 N / cm

- Pressure force of the pressure rollers = 1, 0 + 0.5 N / cm

50 adhesive tape winding bodies in the form of a bow were wound with pressure during the winding process; 50 adhesive tape winding bodies in the form of a bow were wound without pressure.

The geometry of the arched purpose used could be described as follows:

The basic shape of the arched object is fixed at α = 180 °. When rotating around the

Center M is a circle with the radius of curvature r and a so-called

Stroke distance s.

The arched triangle used for the winding tests showed that in the following

Dimensions listed in the table (see Figure 2):

Table 3: Dimensions of the arched purpose used

Table 4: Results of the second series of experiments

As can be seen from the two test series, the adhesive tape winding molds produced using the cores according to the invention had virtually no quality defects.

Claims

claims

1. core for winding self-adhesive coated web-shaped materials, characterized in that the outer contour of the core is formed from at least one essentially round, self-contained segment, the ends of which converge in an edge, with a) the round segment being convex to the axis of the core is formed, b) the surface normals of the round segment are oriented essentially orthogonally to the axis of the core, c) the edge is oriented essentially parallel to the axis of the core and the core has a recess on the inside, so that the roller together with the core on commercially available adhesive tape offices, which have a cylindrical core receiver in particular.

2. core for winding self-adhesive coated, sheet-like materials, characterized in that the outer contour of the core is formed by at least two substantially circular segment-shaped segments, with a) the segments being arranged convex to the axis of the core, b) the surface normals of the segments orthogonal are aligned with the axis of the core, c) the edges at which the segments meet, are aligned parallel to the axis of the core and the core has a recess on the inside, so that the roll and core are attached to commercially available adhesive tape assemblies, which in particular have a cylindrical core receiver , can be used.

3. Core according to claim 2, characterized in that the outer contour of the core is formed by two to seven circular segment-shaped segments of the same shape, which are arranged symmetrically about the axis of the core, wherein a) the segments are arranged convex to the axis of the core, b) the surface normals of the segments are aligned orthogonally to the axis of the core, c) the edges where the segments meet are aligned parallel to the axis of the core.

4. Core according to claims 2 or 3, characterized in that the outer contour of the core is formed by three circular segment-shaped segments of the same shape, which are arranged symmetrically about the axis of the core, wherein a) the segments are arranged convex to the axis of the core , b) the surface normals of the segments are aligned orthogonally to the axis of the core, c) the edges at which the segments meet are aligned parallel to the axis of the core.

5. Core according to claims 2 to 4, characterized in that the edges at which the segments meet are pointed.

6. Core according to claims 1 to 5, characterized in that the edges at which the segments meet have a radius of curvature of less than 3 mm, preferably less than 1 mm, very particularly preferably less than 0.6 mm.

7. Core according to claims 1 to 6, characterized in that the surface normals enclose an angle between 80 ° and 90 ° with the axis of the core.

8. Core according to claims 2 to 7, characterized in that the segments have a circular section angle greater than or equal to 30 °.

9. Core according to claims 1 to 8, characterized in that the segments have a slightly spherical shape.

10. Core according to claim 9, characterized in that the segments have the highest elevation in the center.