EP0943545A2 - Cutting blade for an adhesive tape dispenser - Google Patents

Abstract

The cutting edge has convexly rounded cutting teeth in relation to the adhesive film location and concavely rounded areas between adjacent cutting teeth. Between tooth points and tooth bases are linear areas. The tooth spacing (23) amounts to 1.25mm, the tooth height (24) amounts to 0.4mm, the curvature radius in the area of the contour between two adjacent tooth points (21) is 0.4mm and the curvature radius in the area of the tooth points (22) is 0.13mm.

Description

The invention relates to a dispenser knife for the known adhesive tape dispenser.

• Dispenser von zumeist sehr kompakter Gestalt (nachfolgend auch als Kompaktdispenser bezeichnet), bestehend aus einem offenen oder geschlossenen Gehäuse, welches in seitlicher Ansicht zum Beispiel rund, trapezförmig, rechteckig oder polygonisch geformt sein kann. Die Klebebandrolle wird zur Nutzung auf einen zumeist zylinderförmigen Kemaufnehmer aufgebracht, der etwa mittig im Gehäuse integriert ist. Seitlich enthält der Dispenser einen schlitzartigen Austrittsspalt, aus dem das Klebeband zum Ablängen herausgezogen wird. Üblicherweise befindet sich auf der einen Seite des Austrittsschlitzes das Schneidmesser über das ein Klebebandstück gewünschter Länge abgeschnitten werden kann. Die dem Schneidmesser gegenüberliegende Seite des Austrittsschlitzes ist zumeist als Aufnahmefläche für die haftklebrige Klebebandseite gedacht und derart ausgeformt, daß ein hierauf verklebtes Stück Selbstklebeband leicht abgehoben werden kann.
  Eine beispielhafte Ausführungsform eines entsprechenden Dispensers beschreibt WO 95/23108.
• Dispenser, bei denen das die Klebebandrolle aufnehmende, offen oder auch geschlossen ausgeführte Gehäuse von den Elementen Klebefilmauflage und Schneidmesser räumlich getrennt ist. Entsprechende Dispenser finden als Hand- und als Tischdispenser breite Anwendung. Sie bieten bei verringerter Kompaktheit den Vorteil, daß Klebeband schnell und einfach entnommen werden kann sowie oft eine Einhandbedienung möglich ist.
  Eine beispielhafte Ausführungsform eines entsprechenden Dispensers beschreibt US 4,059,210.
• Dispenser, bei welchen das benötigte Klebeband über zum Beispiel eine Führungsrolle, die gleichzeitig als Andruckrolle fungiert, direkt auf das Substrat übertragen werden kann (nachfolgend auch als Transferdispenser bezeichnet). Zum Abschneiden befindet sich der Andruckrolle vorgelagert ein Schneidmesser oder eine vergleichbare Einrichtung, mittels welchem das Klebeband durch zum Beispiel eine leichte Drehbewegung des Dispensers abgeschnitten werden kann.
  Eine beispielhafte Ausführungsform eines entsprechenden Dispenser beschreibt WO 96/06790.

Dispensers for adhesive tape rolls, also called dispensers, serve the user as a storage container for the adhesive tape rolls themselves and as an application aid for their processing. The primary task of an adhesive tape dispenser is the simple, easy and clean cutting and cutting of adhesive tape strips in the length required for the intended application. Typical embodiments of dispensers include, as basic elements, a supporting housing, a roll core holder, an adhesive tape support and a cutting or tearing device. The following can be distinguished as essential embodiments:

• Dispensers of mostly very compact shape (hereinafter also referred to as compact dispensers), consisting of an open or closed housing, which can be round, trapezoidal, rectangular or polygonal in side view, for example. The tape roll is applied to a mostly cylindrical core receiver, which is integrated approximately in the center of the housing. On the side, the dispenser contains a slot-like exit gap from which the adhesive tape is pulled out to cut it to length. Usually, the cutting knife is located on one side of the outlet slot, via which a piece of adhesive tape of the desired length can be cut off. The side of the exit slot opposite the cutting knife is mostly intended as a receiving surface for the pressure-sensitive adhesive side of the tape and is shaped in such a way that a piece of self-adhesive tape glued thereon can be easily lifted off.
  WO 95/23108 describes an exemplary embodiment of a corresponding dispenser.
• Dispensers in which the housing which holds the roll of adhesive tape, is of open or closed design, is spatially separated from the elements of adhesive film support and cutting knife. Appropriate dispensers are widely used as handheld and table dispensers. With reduced compactness, they offer the advantage that adhesive tape can be removed quickly and easily, and often one-handed operation is possible.
  An exemplary embodiment of a corresponding dispenser is described in US 4,059,210.
• Dispensers in which the required adhesive tape can be transferred directly to the substrate via, for example, a guide roller, which also functions as a pressure roller (hereinafter also referred to as a transfer dispenser). For cutting, the pressure roller is preceded by a cutting knife or a comparable device by means of which the adhesive tape can be cut off by, for example, a slight rotary movement of the dispenser.
  WO 96/06790 describes an exemplary embodiment of a corresponding dispenser.

To cut a section of adhesive tape of the desired length, a corresponding piece of adhesive tape is cut to length and cut off with the cutting knife. The shape and materials of suitable cutting knives vary.
Cutting knives with a toothed cutting edge are most frequently used. The toothed cutting edge can be produced by injection molding dispensers in the injection molding process (see for example tesa film dispenser 55975-87). It is also common to integrate a metal cutting knife into the dispenser. Compared to plastic tooth edges, metal knives generally offer the advantage of higher mechanical strength and greater sharpness, are therefore more durable and more flexible in terms of the materials that can be cut (for example in terms of film thickness and type).

• solche von gezackter Grundstruktur mit aneinandergrenzenden zumeist dreieckigen Schneidzähnen. Eine beispielhafte Ausführungsform zeigt die Figur 5a.
  Die Schneide kann im Bereich der Zahnspitzen (51) und/oder an der Zahnbasis (52) im Übergangsbereich benachbarter Zähne spitz oder auch mehr oder weniger rund ausgeformt sein. Üblicherweise sind die Bereiche (53) zwischen Zahnspitzen (51) und Zahnbasis (52) näherungsweise geradlinig ausgeformt.
• kammförmig ausgeformte Schneidkanten. Eine beispielhafte Ausführungsform zeigt die Figur 5b.
  In diesem Fall besitzen benachbarte Schneidzähne an der Zahnbasis einen definierten Abstand voneinander. Die einzelnen Zähne können über die Zahnhöhe eine etwa gleiche Breite aufweisen oder auch im oberen Bereich verjüngt ausgeformt sein. Einen Grenzfall stellen im Bereich der Zahnspitzen spitz ausgeformte Schneidzähne dar. Im Bereich der Zahnspitzen (51) und/oder im Übergangsbereich der Zähne zur Zahnbasis (52) können die Schneidzähne ebenfalls mehr oder weniger stark rund ausgeformt sein. Üblicherweise sind die Bereiche (53) von den Zahnspitzen (51) zur Zahnbasis (52) wiederum näherungsweise linear ausgeführt.

Typical embodiments of cutting edges include in their front view:

• those of serrated basic structure with mostly triangular cutting teeth. An exemplary embodiment is shown in FIG. 5a.
  In the area of the tooth tips (51) and / or on the tooth base (52) in the transition area of adjacent teeth, the cutting edge can be pointed or more or less rounded. The areas (53) between tooth tips (51) and tooth base (52) are usually approximately rectilinear.
• comb-shaped cutting edges. FIG. 5b shows an exemplary embodiment.
  In this case, adjacent cutting teeth have a defined distance from one another at the tooth base. The individual teeth can have approximately the same width over the tooth height or can also be tapered in the upper region. In the area of the tooth tips (51) and / or in the transition area of the teeth to the tooth base (52), the cutting teeth can also be more or less strongly rounded. The areas (53) from the tooth tips (51) to the tooth base (52) are usually again approximately linear.

In the upper area of the cutting edge, the cutting knives are sufficient to achieve Sharpness optionally beveled. The bevel can have a constant angle exhibit or also run round in the area of the cutting teeth.

Common manufacturing methods for dispenser knives include punching, grinding and wire EDM.
For cutting knives made of hardened steel, the tooth shape is usually generated by grinding (for example in the tesa unwinder 56210) or by wire EDM. For example, the cut is made at an acute angle of 30 ° to the cutting knife level in order to achieve sufficient knife sharpness.
For dispenser knives manufactured using the stamping process, for example, steel strip qualities K 40 and K 60 are used. The punching angle is often 90 ° to the cutting knife level (i.e. runs vertically to the cutting knife level), as implemented in the tesa hand dispenser 5003, for example. In the stamping process, a stamping burr correspondingly perpendicular to the cutting plane is usually formed.
To make it easy to cut off the adhesive film strips, the cutting knives are therefore placed in the dispenser at an angle of attack of, for example, 45 ° to the film level.

With the cutting knives described above, classic transparent ones can be made Self-adhesive tapes with PVC backing, such as the tesa-Film 4104 or the tesa-Film Cut 7121 excellently. A residue-free resumption accordingly Adhesive film strips are also possible throughout.

A disadvantage of dispensers with toothed cutting knives is that, in particular, self-adhesive films which use backing materials with low tear propagation resistance and low ductility cannot be detached without tear from many adhesion reasons. This applies in particular to the widely used adhesive films that use highly stretched biaxially oriented films based on PP homopolymers as carriers, but also for highly stretched films based on other highly crystalline polyolefins and biaxially stretched PETP, to name just a few.
When using a dispenser knife with a serrated cutting edge, the knife contour (tooth structure) forms more or less well on the cutting edges of the cut piece of adhesive tape when cutting off an adhesive film strip, depending on the cutting quality. The type of toothing of the knife edge and the sharp burrs or damage that are often present in the knife very often produce the finest tears in the cut edges of the adhesive film strips obtained.
As a result of the tooth structure shown and the finest tears in the cut edges of the adhesive film strips mentioned, the attempt by the adhesive tape user frequently fails subsequently to detach a bonded adhesive film strip from the adhesive base in one piece. Rather, adhesive film strips obtained in this way frequently tear when the attempt is made to detach them, starting from the cut edges produced by the cutting knives.
In order to completely detach individual adhesive film strips, it is not uncommon that a time-consuming and difficult unwinding of them is subsequently required from the adhesive base. As a result, residues of adhesive film that are difficult to remove, residues of adhesive on the bonding surface and damage to sensitive surfaces are not excluded.

In any case, the use of a is sufficient for easy cutting off sharp cutting knife. This applies in particular in the case of transparent self-adhesive films for materials with high tear resistance, such as mono- and biaxially oriented polypropylene and for those based on polyethylene terephthalate.

The force required to cut off a piece of adhesive film increases with the film thickness and generally decreases significantly as the degree of stretching of the film decreases.

By using very sharp, smooth-edged cutting knives, it is generally possible to detach the aforementioned self-adhesive films easily and without tearing, since in this case the cut edges are not damaged in the form of tears and, due to the high sharpness, films which are difficult to cut can also be cut. The tesa table dispenser 6082 uses smooth cutting knives, which enable an absolutely straight cut edge of the adhesive tape to be portioned. Adhesive film strips cut to length with the tesa table dispenser 6082, which use a biaxially oriented PP carrier, for example tesa-Multi-Film or tesa-Practic-Film, can be removed without tearing in almost all cases.
However, injuries to the fingers in particular when using the aforementioned dispensers cannot be excluded. US 4,175,685 describes an adhesive tape dispenser which uses a cutting unit containing a razor blade. A flexible thread-like material is spirally wrapped around the knife to protect against injuries. The razor blade edge is accessible between individual spiral turns. A cross-cutting smooth knife integrated in a knife bar is used in the tesa industrial table dispenser 6080. The special arrangement and orientation of the cutting knife underneath the knife bar largely excludes the risk of injury to the user. The tesa automat 6056 also uses a knife that runs diagonally to the adhesive tape and is controlled electromagnetically. A risk of injury to the user is also largely excluded.

A disadvantage of the aforementioned tape dispensers with smooth, straight knife edges of high sharpness is the increased risk of injury on the cutting edges, if there is no protective cover and that for processing the adhesive film by manually removing or moving a knife protection cover additional operations are necessary. In the case of the above through a Automation in the cutting process is often a cutting knife complex mechanical construction of the tape dispenser necessary, which manufacturing costs and size of the devices increased and also reduce the functionality can.

The object of the invention was to remedy this, in particular to provide dispenser knives for tape dispensers,
which, analogous to the tooth-shaped metal or plastic knives known today, can be easily integrated into the cutting devices of dispensers of known embodiments,
which produce a cut edge in the adhesive film, so that tear-free removal of applied adhesive films, in particular adhesive films with a carrier film based on mono- and biaxially oriented polypropylene, is possible,
which have a high sharpness of the cutting knife for the adhesive tapes to be cut, but at the same time do not have a significantly increased risk of injury compared to classic dispenser knives with serrated knife edge, which are inexpensive to implement.

This task is solved by a dispenser knife as in the main claim is marked. Advantageous embodiments of the dispenser knife according to the invention are the subject of the subclaims.

• konvex abgerundeten Schneidzähnen und
• konkav abgerundeten Bereichen zwischen benachbarten Schneidzähnen, so daß die durch benachbarte Schneidzähne im abzuschneidenden Klebebandstreifen erzeugten Einschnitte derart an der Kontur der Messerschneide weitergeleitet wird, daß sie näherungsweise ineinanderlaufen, wodurch
  keine oder nur geringfügig Einrisse in Längsrichtung der abgeschnittenen Klebebandstreifen erzeugt werden und die Klebebandstücke nachfolgend von einem Verklebungsuntergrund einreißfrei wiederabgelöst werden können,
  die Zahnhöhe bevorzugterweise geringer oder gleich dem Abstand benachbarter Zahnspitzen zueinander ist,
  die hohe Schärfe der Schneidmesser durch einen optionalen Stanzgrat auf der Zahnkontur insbesondere auf den Zahnspitzen erzielt wird,
  sich die Welligkeit des Schnittbildes durch den Anstellwinkel des Schneidmessers steuern läßt.

Accordingly, the invention relates to a dispenser knife containing a cutting knife edge, wherein
the knife edge has a wavy shape with no or only short linear areas between tooth tips and tooth base, with respect to the adhesive film layer

• convex rounded cutting teeth and
• concavely rounded areas between adjacent cutting teeth, so that the incisions produced by adjacent cutting teeth in the adhesive tape strip to be cut are passed on to the contour of the knife edge such that they run approximately into one another, whereby
  no or only slight tears are produced in the longitudinal direction of the cut off adhesive tape strips and the pieces of adhesive tape can subsequently be detached again without tear from an adhesive substrate,
  the tooth height is preferably less than or equal to the distance between adjacent tooth tips,
  the high sharpness of the cutting knives is achieved by an optional punch burr on the tooth contour, especially on the tooth tips,
  the ripple of the sectional image can be controlled by the angle of attack of the cutting knife.

Figur 1 zeigt eine erfindungsgemäße Abschneidevorrichtung (11) bestehend aus einer Filmauflagefläche (12), an deren Vorderseite (Seite, auf der ein abgelängtes Stück Klebeband entnommen wird) ein gezahntes Schneidmesser (14) integriert ist.
Die Zahnspitzen verlaufen etwa parallel zur Vorderseite der Abschneidevorrichtung und parallel zur Filmauflagefläche (12). Seitlich an der Filmauflagefläche (12) befinden sich optionale Stege (13). Die Filmauflagefläche (12) besitzt vorteilhafterweise eine ausreichend große Fläche, um eine sichere Fixierung des Klebefilms während des Abschneidevorganges zu gewährleisten und insbesondere ein Rutschen des Klebebandes über das Messer beim Abschneiden zu verhindern.
Das Messer (14) ist im Verhältnis zur Höhe der Auflagefläche so angeordnet, daß die Zahnspitzen ca. 2 mm unterhalb bis 3 mm oberhalb selbiger, bevorzugt 0,3 bis 1 mm oberhalb selbiger angeordnet sind. Der Abstand des Messers von der Auflagefläche beträgt ca. 0,1 bis 5 mm, bevorzugt 0,2 bis 2 mm, besonders bevorzugt 0,3 bis 1 mm.

Figur 2 zeigt schematisch die Form des Schneidmessers. Die Kontur der Schneide zeichnet sich dadurch aus, daß ihr Verlauf zwischen den Zahnspitzen (21) abgerundet ist. Die Zahnspitzen (22) weisen ebenfalls eine runde Kontur auf.
Der Abstand (23) benachbarter Zahnspitzen voneinander beträgt ca. 0,3 bis 4 mm, bevorzugt 0,5 bis 3 mm, besonders bevorzugt 1 bis 1,5 mm. Die Höhe (24) der Zähne, gemessen zwischen dem tiefsten Punkt der Kontur (21) und den Zahnspitzen (22), beträgt ca. 0,15 bis 2 mm, bevorzugt 0,2 bis 1,5 mm, besonders bevorzugt 0,3 bis 0,7 mm. Bevorzugt ist die Höhe (24) der Zähne, gemessen zwischen dem tiefsten Punkt der Kontur (21) und den Zahnspitzen (22) geringer als der Abstand (23) benachbarter Zahnspitzen voneinander, besonders bevorzugt geringer als die Hälfte des Abstandes benachbarter Zahnspitzen.
Bevorzugterweise ist die Kontur erfindungsgemäßer Schneidmesser gleichförmig, d. h., Zahnabstand und Höhe sowie die Zahnform variieren innerhalb des Schneidmesssers nicht.
Der Krümmungsradius der Zahnspitzen (22) beträgt ca. 0,05 bis 0,7 mm, bevorzugt 0,07 bis 0,4 mm, besonders bevorzugt 0,1 bis 0,25 mm. Der Krümmungsradius der Kontur zwischen den Zahnspitzen weist Werte von ca. 0,1 bis 2 mm, bevorzugt 0,15 bis 1,4 mm, besonders bevorzugt 0,25 bis 0,7 mm auf.
Die linearen Bereiche zwischen Zahnspitze und Zahnbasis überstreichen weniger als ca. 60% der Höhe der Zähne (24), bevorzugt weniger als 30% der Höhe der Zähne. In einer besonderen Ausführungsform wird die Zahnkontur von zwei runden ineinander übergehenden Bereichen ohne wesentliche lineare Zwischenbereiche gebildet.
In einer weiteren besonderen Ausführungsform ist die zweifache Summe der Krümmungsradien der Zahnspitzen und der Kontur zwischen den Zahnspitzen größer als 75% des Abstandes benachbarter Schneidzähne.

Figur 3 zeigt das seitliche Profil eines erfindungsgemäßen Schneidmessers. Die Materialstärke des Schneidmessers an seiner Basis (31) beträgt ca. 0,1 bis 1,6 mm, bevorzugt 0,2 bis 0,9 mm, besonders bevorzugt 0,3 bis 0,5 mm.
Das Schneidmesser ist bevorzugt im einem Winkel (32) von ca. 20° bis 70°, besonders bevorzugt in einem Winkel von 35° bis 60° in Zugrichtung des Klebefilmes (42) abgeschrägt.
Eine wesentliche Unterstützung beim Eindringen der Metallklinge in den Klebfilm bildet die optional vorhandene, bevorzugt in der gesamten Klingenbreite verlaufende Materialverjüngung zum oberen Ende des Messers. Die Materialverjüngung hat eine eigene Höhe (34) von 0,05 - 1 mm, bevorzugt 0,1 - 0,5 mm, besonders bevorzugt 0,2 - 0,4 mm, wobei die Materialstärke (35) im Ansatz bei ca. 0,1 mm liegt. Die Materialverjüngung wird zum Beispiel als Grat beim Stanzvorgang erhalten.
Das Schneidmesser ist in der Abschneidvorrichtung bevorzugt so eingebaut, daß die abgeschrägte Seite in Zugrichtung des abzutrennenden Klebestreifens liegt.

Figur 4 zeigt den Anstellwinkel (43) des Messers (41) in Richtung des abzulängenden Klebefilmstreifens (42). Der Anstellwinkel beträgt vorteilhafterweise ca. 30° - 110°, bevorzugt 45° - 100°, besonders bevorzugt 60° - 90°. Kleine Anstellwinkel verursachen im allgemeinen eine ausgeprägt wellige Schnittkante, Anstellwinkel nahe 90° lassen eine fast gerade, nur leicht wellige Schnittkante am Klebefilm entstehen.

In the following, advantageous embodiments of the dispenser knife are to be set out on the basis of several figures, without thereby wishing to restrict the invention unnecessarily.

Figure 1 shows a cutting device (11) according to the invention consisting of a film contact surface (12), on the front (side on which a cut piece of adhesive tape is removed) a toothed cutting knife (14) is integrated.
The tooth tips run approximately parallel to the front of the cutting device and parallel to the film contact surface (12). Optional webs (13) are located on the side of the film support surface (12). The film contact surface (12) advantageously has a sufficiently large area to ensure a secure fixation of the adhesive film during the cutting process and in particular to prevent the adhesive tape from slipping over the knife during the cutting process.
The knife (14) is arranged in relation to the height of the support surface so that the tooth tips are arranged approximately 2 mm below to 3 mm above the same, preferably 0.3 to 1 mm above the same. The distance of the knife from the support surface is approximately 0.1 to 5 mm, preferably 0.2 to 2 mm, particularly preferably 0.3 to 1 mm.

Figure 2 shows schematically the shape of the cutting knife. The contour of the cutting edge is characterized in that its course between the tooth tips (21) is rounded. The tooth tips (22) also have a round contour.
The distance (23) of adjacent tooth tips from one another is approximately 0.3 to 4 mm, preferably 0.5 to 3 mm, particularly preferably 1 to 1.5 mm. The height (24) of the teeth, measured between the lowest point of the contour (21) and the tooth tips (22), is approximately 0.15 to 2 mm, preferably 0.2 to 1.5 mm, particularly preferably 0.3 up to 0.7 mm. The height (24) of the teeth, measured between the lowest point of the contour (21) and the tooth tips (22), is preferably less than the distance (23) of adjacent tooth tips from one another, particularly preferably less than half the distance of adjacent tooth tips.
The contour of the cutting knife according to the invention is preferably uniform, ie the tooth spacing and height and the tooth shape do not vary within the cutting knife.
The radius of curvature of the tooth tips (22) is approximately 0.05 to 0.7 mm, preferably 0.07 to 0.4 mm, particularly preferably 0.1 to 0.25 mm. The radius of curvature of the contour between the tooth tips has values of approximately 0.1 to 2 mm, preferably 0.15 to 1.4 mm, particularly preferably 0.25 to 0.7 mm.
The linear areas between the tooth tip and the tooth base cover less than about 60% of the height of the teeth (24), preferably less than 30% of the height of the teeth. In a special embodiment, the tooth contour is formed by two round areas which merge into one another without substantial linear intermediate areas.
In a further special embodiment, twice the sum of the radii of curvature of the tooth tips and the contour between the tooth tips is greater than 75% of the distance between adjacent cutting teeth.

Figure 3 shows the side profile of a cutting knife according to the invention. The material thickness of the cutting knife at its base (31) is approximately 0.1 to 1.6 mm, preferably 0.2 to 0.9 mm, particularly preferably 0.3 to 0.5 mm.
The cutting knife is preferably bevelled at an angle (32) of approximately 20 ° to 70 °, particularly preferably at an angle of 35 ° to 60 ° in the pulling direction of the adhesive film (42).
The optionally available material taper towards the upper end of the knife, which runs preferably across the entire width of the blade, provides essential support when the metal blade penetrates the adhesive film. The material taper has its own height (34) of 0.05-1 mm, preferably 0.1-0.5 mm, particularly preferably 0.2-0.4 mm, the material thickness (35) starting at about 0 , 1 mm. The material rejuvenation is obtained, for example, as a burr during the punching process.
The cutting knife is preferably installed in the cutting device in such a way that the beveled side lies in the pulling direction of the adhesive strip to be separated.

FIG. 4 shows the angle of attack (43) of the knife (41) in the direction of the adhesive film strip (42) to be cut to length. The angle of attack is advantageously approximately 30 ° to 110 °, preferably 45 ° to 100 °, particularly preferably 60 ° to 90 °. Small angles of attack generally cause a distinctly wavy cutting edge, angles of attack close to 90 ° give rise to an almost straight, only slightly wavy cutting edge on the adhesive film.

Self-adhesive films can be made by means of the cutting devices shown in FIG with, for example, biaxially oriented polypropylene carrier, with biaxially stretched Polyethylene terephthalate carrier, with cellulose acetate carrier with cellophane carrier or with PVC strips, to name just a few, are excellently cut. A smooth to wavy Cutting edge, which has no or only very small microscopic injuries in the form of sharp cuts or cracks in the longitudinal direction of the cut off adhesive tape is usually generated both if the self-adhesive film strips in the middle of the front of the cutter cut off downwards, i.e. without deflection to the left or to the right, or also with lateral deflection, i.e. cut off diagonally to the left or to the right become.

It is essential for a very easy severing that the self-adhesive film through the tapered material experiences incisions at the tooth tips. This is shown in Figure 3 Blade edge described in the sharp area to choose high enough to the usual self-adhesive films with a thickness of approx. 0.02 mm to approx. 0.07 mm are complete to sever. The incision through the tooth tips is subsequently on the Knife contour forwarded such that a smooth to slightly wavy cutting edge over the entire width of the self-adhesive film used is generated. The cut edge experiences in particular no or only to a very small extent microscopic injuries in the form of sharp cuts or cracks in the longitudinal direction of the cut off adhesive film strips, on which the adhesive film tear when detached can.

The low risk of injury with an otherwise very high sharpness of the blade will in the cutting device according to the invention by the two-stage material taper the cutting blade achieved. The sharp protruding area of the blade is merely able to scratch the surface of the skin slightly. A deeper penetration of the Teeth into the skin is prevented by the relatively obtuse angle (32) in FIG. 3.

For example, galvanized or nickel-plated punchable steel strip can be used as the blade material can be used to name just a few materials. Different plastics such as PS or ABS are also suitable. For versions in plastic must however, generally a significantly reduced service life compared to a metal knife of the cutting knife are accepted.

Cutting devices for self-adhesive films according to the invention can be in one large number of dispenser types can be used. Suitable dispenser types include Table and hand-held dispensers, where the one that holds the tape roll The housing is separate from the film support and the cutting device, compact dispenser as well as transfer dispensers as previously described.

The above statements are examples.

Test methods Testing for tear-free redetachment of applied self-adhesive films

10 strips of adhesive film each with a length of approx. 3 cm are cut off on the dispenser. The The tape is removed by pulling the adhesive film at an angle of approx. 75 ° to the Front of the cutting device without lateral deflection of the adhesive film strips (Cut off from). The experiment can also be carried out with lateral deflection of the Adhesive films take place (oblique cutting). In the latter case, the adhesive film each cut off from one side. The adhesive film strips obtained are Then, by rubbing lightly with your finger, free of air bubbles on plastic plates consisting of hard PVC (type: Kömadur WA; supplier: Fa. Krüger / Wedel) glued, then rolled over 5 times with a 1 kg pressure roller. The one with adhesive film strips PVC sheets provided are subsequently 3 days in the climatic room (T = 23 ± 2 ° C; Humidity = 50 ± 10%).

To check for tear-free redetachment, the adhesive strips are removed manually from the PVC primer removed. To do this, the adhesive film strips are started from a corner peeled off with your fingernail, then carefully up to half the length of the adhesive film peeled off. The adhesive film strips are on the opposite separating edge replaced in the same way. A total of 20 attempts are made to remove the 10 adhesive film strips performed. The trials are counted in which the adhesive film strips let it peel off the PVC without tearing at the cut edge.

Testing for the ability to cut off pieces of adhesive film

Prüfung auf einreißfreies Wiederablösen applizierter Selbstklebefilme" beschrieben. Abgeschnitten wird ohne seitliche Auslenkung der Klebefilmstreifen (Abschneiden nach vorn). Die zum Abtrennen der Klebefilmstreifen benötigte Kraft wird subjektiv mit derjenigen verglichen, die zum Abtrennen am tesa-Tischabroller 6059 notwendig ist. Die Beurteilung lautet

• mäßig schwer",
  wenn die Abtrennkraft subjektiv derjenigen Kraft vergleichbar ist, die zum Abtrennen eines Stückes tesa-Multi-Film am tesa-Tischabroller 6059 nötig ist;
• "sehr leicht",
  wenn die Abtrennkraft subjektiv derjenigen Kraft vergleichbar ist, die zum Abtrennen eines Stückes tesa-Multi-Film an einem tesa-Tischabroller 6059 benötigt wird, bei welchem das vorhandene gezahnte Schneidmesser gegen ein Rasierklingenmesser ausgetauscht ist (Klingendicke = 0,3 mm; Material: Stahl; Schneide beidseitig senkrecht geschliffen; Schleifwinkel = 10° je Seite).

10 strips of adhesive film each with a length of approx. 3 cm are cut off on the dispenser. The separation takes place as below

Testing for tear-free redetachment of applied self-adhesive films "is described. The adhesive film strips are cut off without lateral deflection (cutting to the front). The force required to remove the adhesive film strips is subjectively compared with that required to tear off the tesa table dispenser 6059. The assessment is

• moderately difficult ",
  if the severing force is subjectively comparable to the force required to tear off a piece of tesa-Multi-Film on the tesa table dispenser 6059;
• "very easy",
  if the severing force is subjectively comparable to the force required to sever a piece of tesa-Multi-Film on a tesa table dispenser 6059, in which the toothed cutting knife is exchanged for a razor blade knife (blade thickness = 0.3 mm; material: steel ; Cutting edge vertically ground on both sides; grinding angle = 10 ° on each side).

example 1

With the housing of a tesa hand dispenser 5003 the existing metal knife is cut through replaced a knife according to the invention. The dimensions according to Figure 2 are as follows: The Tooth distance (23) is 1.25 mm, the tooth height (24) is 0.4 mm, the radius of curvature in the area of the contour between two adjacent tooth tips (21) is 0.4 mm, the radius of curvature in the area of the tooth tips (22) is 0.13 mm. Of the Angle of attack of the knife to the film (43) according to FIG. 4 is 80 °. The cutting knife is beveled in the pull-off direction (42) at an angle of 45 °. The height of the ridge in the area of the tooth tips (34) is approx. 0.3 mm, the material thickness at the base of the ridge (35) approx. 0.1 mm.

Self-adhesive films # 1 to # 6 with a width of 19 mm are tested for their ability to be cut off, the structure of the cut edge and tear-free detachable adhesive film strips. The following properties result:

In all cases, the cutting device according to the invention results a slightly wavy cut edge. All of the adhesive films can be used for both Cutting off from as well as when cutting obliquely or respectively very light, the calender film based on a mixture of PE and EVAc copolymer detach easily. Almost all adhesive strips can be torn after gluing detach. For comparison, the adhesive films # 1 to # 3 on the with an original knife equipped tesa dispenser 5003 processed. The severing will be in all Cases as easy when cutting obliquely and as moderately difficult when cutting in the middle judged. A tear-free redetachment of glued adhesive film strips is only possible in approx. 10 to 30% of all cases.

Example 2

In a tesa hand dispenser 5003 modified analogously to the example, the height of the knife tips is varied over the contact surface (12) in FIG. 1. tesa-Multi-Film (= adhesive film # 2 from example 1) is compared for cutting ability, structure of the cut edge and tear-free redetachment of glued adhesive film strips. The distance between the cutting knife (14) and the film contact surface (12) is 0.5 mm. The following characteristics are the result: attempt Knife height above the contact surface Can be cut to the front / side Cutting edge tear-free redetachment 2.1 0 mm easy // very easy slightly wavy > 80% 2.2 0.5 mm easy // very easy slightly wavy > 90% 2.3 1.0 mm easy // very easy slightly wavy > 80% 2.4 1.5 mm easy // very easy slightly wavy > 80% 2.5 2.0 mm easy // very easy slightly wavy > 70%

As a result of the distance between the cutting knife (14) and the film contact surface (12) the knife lies in one plane with the knife rest, d. that is, the knife height above the Film contact area be 0 mm. In the present case, the knife tips should not protrude more than 1 mm beyond the film support surface, otherwise a secure support the film is not realized on the film support surface. The tear-free redetachment the self-adhesive film in the present example is compared to the original dispenser knife of the tesa hand dispenser 5003 (see example 1) significantly improved in all cases.

Example 3

A tesa hand dispenser 5003 is provided with a cutting knife according to the invention in accordance with Example 1. The position of the bevel (32) of the cutting knife is varied (see FIG. 3). The tapered side of the knife is tested in the pulling direction and against the pulling direction of the adhesive film strip to be cut. tesa-Multi-Film (= adhesive film # 2 from example 1) is compared for cutting ability, structure of the cut edge and tear-free redetachment of glued adhesive film strips. The following properties result: attempt Punched bevel Can be cut forward // laterally Cutting edge tear-free redetachment 3.1 in the pulling direction of the adhesive film to be cut easy // very easy slightly wavy > 80% 3.2 against the pulling direction of the adhesive film to be cut easy // very easy slightly wavy approx. 50%

A very easy cutability of the used is used for all experimental setups Adhesive film observed with formation of a slightly wavy cut edge. When aligning the bevel (32) of the punching knife in the direction of the pulling direction to be cut The adhesive film can be tear-free in more than 80% of the cases detach. However, the knife with the punch bevel opposite to the direction of pull installed, the adhesive film tears significantly more often. The cause can be seen under light microscopy Detect very fine incisions in the longitudinal direction of the adhesive film. in the Comparison to the original knife of the tesa hand dispenser 5003 is nevertheless a clear one Improvement realized.

Example 4

A tesa hand dispenser 5003 modified analogously to Example 1 is provided with different cutting knives. The tooth cutting edges correspond to those of example 1. The angle of attack of the cutting knife is varied in the direction of the adhesive film strips to be cut. tesa-Multi-Film (= adhesive film # 2 from example 1) is compared for cutting ability, structure of the cut edge and tear-free redetachment of glued adhesive film strips. The following properties result: attempt Angle of attack of the knife to the film level Can be cut forward // laterally Cutting edge tear-free redetachment 4.1 80 ° easy // very easy slightly wavy > 80% 4.2 60 ° easy // very easy moderately wavy > 80% 4.3 45 ° easy // very easy very wavy > 80% 4.4 30 ° easy // very easy very wavy > 80%

The easy cutting ability is given for all angles of attack. The amplitude of the ripple, that is formed on the knife edge increases with the smaller angle of attack of the knife. The course of the cut is clean in all cases and without damage longitudinal. All patterns can be at least 80% without tears replace.

Example 5

Different dispense available on the market are compared to a tesa hand dispenser 5003, which is equipped with cutting knives according to the invention, for tear-free removal of tesa-Multi-Film.

Legend of the columns:

A

punched (ST) / sharpened (Schl) knife

B

Radius of curvature of the knife tips

C.

Radius of curvature in the area of the contour between the tooth tips

D

linear cutting area between tooth tips and tooth base

E

Punching angle

F

Can be cut forward // laterally

G

tear-free resumability

Point dispenser knife with punching angles close to 90 ° (tests 5.1, 5.2, 5.3, 5.5 and 5.6) in all cases low values for tear-free resumability. The Cross-sectional images obtained are typically very uneven, which can be cut off required forces high. In no case the cutting knife shape is clean on the cut off adhesive film and thus creates a clean cut. In many In some cases, the adhesive film tears irregularly when it is cut and it becomes no rectangular adhesive film strips received. Numerous microscopic incisions in Longitudinal direction of the cut off adhesive film strips can be demonstrated which is the cause of the unsatisfactory results in residue-free Are resuming. The 3M table dispenser HE 200 with a punching angle of 30 ° also gives low values for residue-free resumption, which essentially due to the low radii of curvature in the area of the tooth tips Cutting knife as well as in the area of the contour between adjacent cutting teeth is caused. The tesa table dispenser 56210 is due to the small radius of curvature in the area of the contour between adjacent tooth tips and the low punch angle with a tear-free repeatability of over 40% well above the previously described dispensers (experiment 5.4). Has a disadvantage the high sharpness of the tooth tips, which is in the small radius of curvature of only 0.03 mm. In this case, the high sharpness of the teeth creates what also continues over the tooth flanks, incisions in the direction of the cut off Adhesive film strips, which will subsequently attempt to remove the adhesive film strips from the substrate fails to detach in one piece. The also has a disadvantage linear (straight) course of the knife contour in the intermediate area of tooth tips and Tooth base.

• eines Stanzwinkels von << 90°,
• hoher Werte für das Verhältnis Zahnabstand zu Zahnhöhe,
• einer durchgehend runden Kontur der Messerschneide mit
  • mäßigen Krümmungsradien im Bereich der Zahnspitzen,
  • niedrigen Krümmungsradien im Bereich der Kontur zwischen benachbarten Schneidzähnen
  sowie der Integration einer Materialverjüngung im Bereich der Zahnspitzen eine leichte beziehungsweise sehr leichte Schneidbarkeit von tesa-Multi-Film auf. Die durch benachbarte Schneidzähne im abzuschneidenden Klebebandstreifen erzeugten Einschnitte werden derart an der Kontur der Messerschneide weitergeleitet, daß sie näherungsweise ineinanderlaufen, wodurch keine oder nur geringfügig Einrisse in Längsrichtung der abgeschnittenen Klebebandstreifen erzeugt werden und die Klebebandstücke nachfolgend von einem Verklebungsuntergrund einreißfrei wiederabgelöst werden können.

Knives according to the invention (experiments 5.8 a, b, c) show in all cases by implementation

• a punching angle of << 90 °,
• high values for the ratio of tooth spacing to tooth height,
• with a continuous round contour of the knife edge
  • moderate radii of curvature in the area of the tooth tips,
  • low radii of curvature in the area of the contour between adjacent cutting teeth
  as well as the integration of a material rejuvenation in the area of the tooth tips make tesa-Multi-Film easy or very easy to cut. The incisions produced by adjacent cutting teeth in the adhesive tape strip to be cut are forwarded to the contour of the knife edge in such a way that they run approximately into one another, whereby no or only slight tears are produced in the longitudinal direction of the cut adhesive tape strips and the pieces of adhesive tape can subsequently be detached without tear from a bonding surface.

Claims (13)

Dispenser knife for an adhesive tape dispenser, in particular consisting of a housing, a roller core receptacle and an adhesive tape support arranged in front of the dispenser knife, the dispenser knife containing a knife edge which has a wavy shape, with cutting teeth rounded off convexly with respect to the adhesive film overlay, and concave rounded areas between adjacent cutting teeth linear areas between the tooth tips and the tooth base, the linear areas between the tooth tip and the tooth base covering less than 60% of the height of the teeth, preferably less than 30% of the height of the teeth,
so that the incisions produced by adjacent cutting teeth in the adhesive tape strip to be cut are forwarded to the contour of the knife edge in such a way that they run approximately into one another, whereby no or only slight tears in the longitudinal direction of the cut adhesive tape strips are produced and the adhesive tape pieces can subsequently be detached from a bonding surface without tearing. Dispenser knife according to claim 1, characterized in that between tooth tips and tooth base no linear areas is provided. Dispenser knife according to claims 1 and 2, characterized in that the Dispenser knife is arranged in relation to the height of the contact surface so that the tooth tips 2 mm below to 3 mm above the same, preferably 0.3 to 1 mm are arranged above the same and / or the distance of the dispenser knife from the contact surface is 0.1 mm to 5 mm, preferably 0.2 mm to 2 mm, particularly preferably 0.3 mm to 1 mm. Dispenser knife according to claims 1 to 3, characterized in that the Dispenser knife an angle of attack in the direction of the adhesive film strip to be cut 30 ° to 110 °, preferably 45 ° to 100 °, particularly preferably 60 ° to 90 °. Dispenser knife according to claims 1 to 4, characterized in that the dispenser knife
has at its base a material thickness of 0.1 mm to 1.6 mm, preferably 0.2 mm to 0.9 mm, particularly preferably 0.3 mm to 0.5 mm,
is chamfered at an angle of 20 ° to 70 °, particularly preferably at an angle of 35 ° to 60 °, in the pulling direction of the adhesive film and / or
has a material taper towards the upper end, in particular across the entire width of the blade. Dispenser knife according to claim 5, characterized in that the material taper a height of 0.05 mm to 1 mm, preferably 0.1 mm to 0.5 mm, particularly preferably 0.2 mm to 0.4 mm, the material thickness in Approach is 0.1 mm. Dispenser knife according to claims 1 to 6, characterized in that the Distance between adjacent tooth tips from 0.3 mm to 4 mm, preferably 0.5 mm up to 3 mm, particularly preferably 1 mm to 1.5 mm. Dispenser knife according to claims 1 to 7, characterized in that the twice the radius of curvature of the tooth tips and the contour between the tooth tips are greater than 75% of the distance between adjacent tooth tips is. Dispenser knife according to claims 1 to 8, characterized in that the Height of the teeth, measured between the concave rounded area between adjacent cutting teeth and the tooth tips, is less than the distance Adjacent tooth tips from one another, particularly preferably less than half the distance between adjacent tooth tips. Dispenser knife according to claims 1 to 9, characterized in that the Height of the teeth, measured between the concave rounded area between adjacent cutting teeth and the tooth tips 0.15 mm to 2 mm, preferred 0.2 mm to 1.5 mm, particularly preferably 0.3 mm to 0.7 mm. Dispenser knife according to claims 1 to 10, characterized in that the Radius of curvature of the tooth tips 0.05 mm to 0.7 mm, preferably 0.07 mm to 0.4 mm, particularly preferably 0.1 mm to 0.25 mm, and / or the radius of curvature the contour between the tooth tips values of 0.1 mm to 2 mm, preferred 0.15 mm to 1.4 mm, particularly preferably 0.25 mm to 0.7 mm. Dispenser knife according to claims 1 to 11, characterized in that the Dispenser knife has a punching ridge on the tooth contour, especially on the tooth tips having. Dispenser knife according to claims 1 to 12, characterized in that the Contour of the dispenser knife is uniform.

Images