The Invention is a hand-held tool to remove a liner protecting pressure-sensitive adhesives and tapes. While the Invention is useful for removing a liner in any circumstance, it is particularly useful for removing an exposed secondary liner from a pressure-sensitive adhesive disposed on the secondary side of a tape carrier where the opposing primary side of the tape carrier is adhered to a surface.
Two-sided tape is widely used in the assembly of manufactured objects, such as windows, electronics and automobiles. The two-sided tape comprises a tape carrier coated on both sides with a pressure-sensitive adhesive and with a liner on one or both sides covering the pressure-sensitive adhesive. As used in this document, the side of a tape carrier that will be adhered to a surface is referred to as the ‘primary’ side and the pressure-sensitive adhesive disposed on the primary side is the ‘primary pressure-sensitive adhesive.’ If present, a ‘primary liner’ protects the primary pressure-sensitive adhesive. The opposite side of the tape carrier is referred to in this document as the ‘secondary’ side of the tape carrier. The ‘secondary pressure-sensitive adhesive’ is disposed on the secondary side of the tape carrier and the ‘secondary liner’ protects the secondary pressure-sensitive adhesive.
The tape carrier of a two-sided tape is very thin compared to its length and width and may be composed of a polymer film, foam or paper. The primary liner (if present) and the secondary liner may be composed of polymer film or paper coated with a release agent. The primary or secondary liner is engineered to adhere only weakly to the primary or secondary pressure-sensitive adhesive, allowing the primary or secondary liner to be removed from the primary or secondary pressure-sensitive adhesive and hence from the tape carrier. When the primary or secondary liner is removed, the corresponding pressure-sensitive adhesive is exposed and may aggressively attach the tape carrier to any object to which the adhesive may come in contact. The primary or secondary liner prevents unintended, premature adhesion of the primary or secondary pressure-sensitive adhesive and makes possible the storage, transportation and use of the two-sided tape.
To assemble a manufactured object using two-sided tape with pressure-sensitive adhesive, an operator may manually remove the primary liner from the primary side of the carrier to expose the primary adhesive. The operator applies the exposed primary adhesive to a first surface to be joined, such as a flat surface. The primary pressure-sensitive adhesive and therefore the primary side of the carrier then is adhered to the surface. The operator then manually removes the secondary liner from the secondary side of the tape carrier, revealing the secondary pressure-sensitive adhesive. The operator then will engage a second surface to be joined to the secondary adhesive on the secondary side of the carrier, adhering the second surface to the secondary pressure-sensitive adhesive and hence to the first surface.
While the secondary liner is weakly joined to the secondary pressure-sensitive adhesive, the secondary liner nonetheless may be challenging to remove from the adhesive. Several tools have been developed to assist in separating a liner from pressure-sensitive adhesive applied to a tape or label. Most of the prior liner removal tools involve a blade or wedge that passes into the pressure-sensitive adhesive between the carrier and the liner. See, for example, U.S. Pat. No. 3,040,802 to Frazer issued May 22, 1958, which has a pointed blade against which an operator presses the end of a tape so that the point passes between the carrier and liner. Another example is U.S. Pat. No. 6,685,795 to Braun, issued Feb. 3, 2004, in which a pointed wedge presses into the adhesive between the carrier and liner. See also U.S. Pat. No. 6,158,493 to Hildebrand, issued Dec. 12, 2000, that teaches a hand-held chisel that is pressed between the liner and carrier. Similar to Hildebrand are U.S. Pat. No. 4,128,452 to Johnson issued Dec. 5, 1978 and U.S. Pat. No. 4,248,660 to Johnson issued Feb. 3, 1981. See also U.S. Pat. No. 5,022,951 to Behlmer issued Jan. 11, 1991 that teaches sliding a blade under a label to remove the label from a liner. Some prior patents combine a blade passing between the carrier and liner with a tape dispenser. See U.S. Pat. No. 3,107,193 to De Neui issued Mar. 16, 1960 and U.S. Pat. No. 3,477,896 to Townsend issued Nov. 11, 1969. All of the blade and wedge tools may damage the adhesive layer that is engaged by the blade or wedge.
EP published application 90102322.6 by Krause published Aug. 22, 1990 takes a different approach; namely, the Krause tool pushes the carrier and liner in opposite directions until the shear force exceeds the shear strength of the adhesive-to-liner bond, separating the adhesive and liner.
The prior art does not teach the liner removal tool of the Invention.
The Invention is a hand-held tool for the removal of a secondary liner from secondary pressure-sensitive adhesive disposed on the secondary side of the tape carrier of a two-sided tape where a primary side of the tape carrier is adhered to a surface. This situation frequently occurs when using two-sided tape during product assembly in manufacturing operations. The tool of the Invention is used to peel the exposed secondary liner from the secondary pressure-sensitive adhesive without damage to either the tape carrier or to the secondary pressure-sensitive adhesive.
The tool of the Invention peels the secondary liner from the secondary pressure-sensitive adhesive at any point along the secondary liner when the width and length are substantially the same, but toward the end of the secondary liner when the width and length are substantially not the same. The tool operates by penetrating the exposed secondary liner surface using a plurality of sharp points. The operator then rotates the tool to lift the sharp points from the tape while the sharp points are secured to the secondary liner. The force applied by the plurality of sharp points to the secondary liner exceeds the peeling force to peel the secondary liner from the secondary pressure-sensitive adhesive, lifting the end of the secondary liner from the secondary pressure-sensitive adhesive. The use of the plurality of sharp points provides that the force applied by any one of the sharp points to the secondary liner is less than the force that would cause tearing of the secondary liner. While any number of sharp points is contemplated by the Invention, the minimum number believed to be effective is three sharp points while five sharp points have proven suitable in practice.
The hand tool of the invention includes a handle that may be gripped by a user. The handle defines a first end and a second end. The first end of the handle may define a handle fulcrum, which may be curved. The user may grip the handle and may slide the handle fulcrum along the surface of the exposed secondary liner of a two-sided tape where the primary side of the two-sided tape is adhered to a surface. The sharp points are attached to and supported by the handle.
Each of the sharp points defines a point axis tangent to the sharp point. The point axes in combination define a mathematical plane. The plurality of sharp points in combination define a mathematical line normal to the point axes of the sharp points, with the mathematical line defined by the sharp points coincident with the mathematical plane. The mathematical plane is substantially tangent to, but exterior to, the handle fulcrum. The geometric relationship among the sharp points and between the sharp points and the handle allow the hand tool to successfully remove the secondary liner from the secondary pressure-sensitive adhesive on the secondary side of the tape carrier without damage to the secondary pressure-sensitive adhesive or tape carrier.
The sharp points may be supported by and connected to the handle by one or more pointed members. The one or more pointed members have a curved surface. A first portion of the pointed member curved surface proximal to the sharp points defines a first pointed member radius of curvature. A second portion of the pointed member curved surface that is immediately adjacent to the first pointed member portion has a second radius of curvature. The second pointed member portion is separated from the sharp points by the first pointed member portion and the second pointed member radius of curvature is greater than the first pointed member radius of curvature.
When the user rotates the hand tool with the sharp points penetrating the liner, the curved surface of the first portion of the pointed member engages the exposed liner surface close to the sharp points. The location on the curved surface of the pointed member that touches the exposed liner surface defines a pointed member fulcrum and the hand tool defines a lever of the second class. The load moved by the lever is the resistance to peeling of the liner. The motive force for the lever is provided by the user pressing on the handle and the pointed member fulcrum provides the fulcrum about which the lever acts.
The pointed member fulcrum moves as the user rotates the hand tool and different locations on the curved surface of the pointed member touch the exposed secondary liner surface. When the first portion of the pointed member contacts the exposed secondary liner surface, the pointed member fulcrum is close to the sharp points, the radius of curvature is relatively small and the mechanical advantage of the lever is relatively large. When the user rotates the hand tool so that the second portion of the pointed member contacts the exposed secondary liner surface, the radius of curvature is relatively large, the pointed member fulcrum is farther from the sharp points, and the mechanical advantage of the lever is relatively small.
The relatively large mechanical advantage when the curved surface of the first portion of the pointed member first contacts the exposed secondary liner surface provides that a relatively large movement of the handle results in a relatively small movement of the sharp points, assisting in separating the liner from the pressure-sensitive adhesive and reducing the likelihood of tearing or delaminating the liner. The relatively small mechanical advantage when the second portion of the pointed member defines the pointed member fulcrum causes a relatively large movement of the sharp points for a relatively small movement of the handle, hastening the removal of the secondary liner from the secondary pressure-sensitive adhesive.
Alternatively, the hand tool may dispense with the handle fulcrum, in which event the mathematical plane defines an acute angle with respect to the longitudinal axis of the handle. The user may grip the handle so that the user's finger acts as the handle fulcrum. In all other respects, the hand tool without the handle fulcrum acts in the same manner as the hand tool with the handle fulcrum and described above.
The handle may be configured to be secured to one or more of the user's fingers on one hand. For example, the handle may comprise a ring defining an opening through which a user's finger may penetrate. The opening defines a ring axis generally normal to the opening. The mathematical line defined by the sharp points is substantially parallel to the ring axis. The ring may be substantially rigid. Alternatively, the ring may define a resilient or flexible strap that defines the opening through which the user's finger, or two or more fingers, may penetrate and that defines the ring axis. The outside of the ring may serve as the handle fulcrum. In all other respects, the ring embodiment operates as described above.
As an alternative, a bridge may join the sharp points proximal to the mathematical line and may define the depth to which the sharp points may penetrate the secondary liner. The bridge prevents the sharp point from penetrating the liner to a depth any greater than the limit defined by the combination of the bridge and the sharp points. The bridge assists in preventing damage to the secondary pressure-sensitive adhesive and tape carrier by the sharp points.
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The secondary liner 4 adheres only weakly to the secondary pressure sensitive adhesive 12. To adhere an object to the secondary pressure-sensitive adhesive 12, a user will remove the secondary liner 4 from the secondary pressure-sensitive adhesive 12 and will apply pressure between the object and the secondary pressure-sensitive adhesive 12.
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The relatively long handle 22 and the relatively short distance between the sharp points 26 and the location on the handle fulcrum 24 in contact with the secondary liner surface 18 gives the user exquisite control over the location of the sharp points 26 with respect to the secondary liner surface 18.
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While the handle fulcrum 24 is shown as being curved, the handle fulcrum 24 may be of any suitable shape, such as rectangular, triangular, a blade, or any other shape that provides a location about which to rotate the hand tool 2 on the exposed secondary liner surface 18 and which has the relationship to the mathematical plane 32 described above.
The pointed members 20 may be composed of any suitable material, for example a polymer, sheet metal or wire. The sharp points 26 may be composed of any suitable material, for example metal wire, sharpened sheet metal, or sintered carbide. Any material that can be sharp enough and strong enough to penetrate the secondary liner surface 18 and liner 4 and to pull the liner 4 from engagement with the secondary pressure-sensitive adhesive 12 is suitable for the sharp points 26.
The following is a list of numbered elements from the drawings and specification.
An element identified by name or number and described with respect to a figure has the same meaning when the element number is included in any other figure, unless the context requires a different meaning.
Hand tool 2
Secondary liner 4
Two-sided tape 6
Tape carrier 10
Secondary pressure-sensitive adhesive 12
Primary pressure sensitive adhesive 13
Primary side 14
Secondary side 16
Secondary liner surface 18
Plurality of pointed members 20
Handle fulcrum 24
Sharp point 26
Mathematical line 28
Point axis 30
Mathematical plane 32
First portion of the pointed member 34
First radius of curvature 36
Second portion of the pointed member 38
Second radius of curvature 40
Handle longitudinal axis 42
Arrow 44 indicating rotation of the tool
Arrow 46 indicating lateral movement of the tool
Acute angle 48
Pointed member fulcrum 50
Handle first end 54
Handle second end 56
Ring axis 58