Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Adhesive outermost layer
Reexamination Certificate
1999-04-06
2002-10-01
Truong, Duc (Department: 1711)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Adhesive outermost layer
C428S340000, C428S391000, C428S402000
Reexamination Certificate
active
06458454
ABSTRACT:
FIELD OF THE INVENTION
The present invention refers to a removable holding device, such as a wall hook, which bears a pressure-sensitive adhesive layer.
BACKGROUND OF THE INVENTION
Holding devices such as hooks bearing pressure-sensitive adhesive tapes are known, for example, from U.S. Pat. No. 4,671,480 and U.S. Pat. No. 4,756,498. Many pressure-sensitive adhesive materials suggested for such applications either split apart under stress of removal, leaving stubborn residue on the surface which must be removed with the aid of organic solvents and mechanical scraping tools, or they form a permanent bond with the surface. Acrylate based pressure-sensitive adhesive materials having high adhesion strength and quick build-up of adhesion strength which are useful for bonding structural components, are described, for example, in Japanese patent JP 8-109,356.
To overcome these problems, pressure-sensitive adhesive tape holding devices have been developed which allow the adhesive bond to be broken on demand by stretching the adhesive layer in the plane of the adhesive bond. These holding devices which are described, for example, in WO 92/11,333, U.S. Pat. No. 5,507,464 or U.S. Pat. No. 5,409,189 have the advantage that they provide strong bonding to smooth and rigid surfaces and also provide a pressure-sensitive adhesive bond that can be broken at any desired time. The removal mechanism requires, however, that a section of the pressure-sensitive adhesive tape protrude from the bonding plane to aid in grasping and debonding, a feature often undesirable from an aesthetic point of view. Additionally, most of the pressure-sensitive adhesives used are opaque and therefore less suitable for bonding transparent objects.
There was therefore a need for providing a holding device bearing a pressure-sensitive adhesive which is attachable to rigid surfaces whereby the pressure-sensitive adhesive is easily removable from the surface on demand, which holding device does not exhibit the disadvantages of the holding devices described in prior art or exhibits them to lesser degree only.
SUMMARY OF THE INVENTION
The present invention refers to a holding device which is attachable to a smooth and rigid surface comprising a holding means bearing an exposed pressure-sensitive adhesive layer wherein the pressure-sensitive adhesive is obtainable by polymerizing a precursor comprising
a) a monomer component which contains one or more alkyl acrylates, the aikyl groups of which have an average of 4-14 C atoms, and at least 5 phr of at least one copolymerizable monomer having a polar group,
b) 5-15 phr of hydrophobic silica,
c) one or more polymerization initiators, and
d) one or more crosslinker compounds in a concentration resulting in a crosslink density obtainable by using hexanedioldiacrylate as a reference crosslinker compound in the concentration of between 0.06-0.13 phr,
and exhibits
a compliance of between 5×10
−6
to 2×10
−5
m
2
/N (5×10
−7
to 2×10
−6
cm
2
/dyne), and
a toughness of between 2.9×−10
3
to 9.8×10
3
kg/m
2
(6×10
2
to 2×10
3
pounds/inch
2
)
DETAILED DESCRIPTION OF THE INVENTION
The present invention concerns a holding device comprising an exposed pressure-sensitive adhesive layer. The holding device can exhibit various forms and can comprise, for example, one or several pieces.
One-piece constructions such as, for example, one-piece hooks are described, for example, in WO 92/11,333, p. 12, ln. 18 to p. 13, ln. 23.
The holding device can also comprise an anchoring device the front surface of which bearing the pressure-sensitive adhesive layer and the rear surface of which comprising engagement means to engage a cooperative feature of a holder.
An example of a holding device comprising an anchoring device which is designed to releasably engage the rearview mirror of a car, is described in co-pending PCT patent application PCT/US 96/05,416 (see, in particular, FIG.
1
and
2
). This anchoring device is commercially available under the trademark GM #5-3823 from SSI Technology, Inc., of Janesville, Wis. Other commercially available mirror buttons include the following non-exclusive list S-3756, S-3823 and S-2525, all available from SSI Technology, Inc., of Janesville, Wis.
Another example of a holding device comprising an anchoring device which is suitable in the present invention is described in EP 0,289,962. This anchoring device has a forwardly protruding nose forming the front surface which carries the pressure-sensitive adhesive layer and a rear surface comprising a recess surrounded by a circular rim which forms a base for removable supporting hooks or the like.
It is also possible that the holding device according to the present invention consists of the pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer according to the invention can be used for mounting objects such as, for example, body side moldings on cars, pictures frames, posters or graphics.
The holding devices described are merely illustrative and it will be recognized that numerous other designs can be used. Holding devices which comprise a holding means of one or more pieces and a pressure-sensitive adhesive layer which is attached to at least one of these pieces, are preferred.
In case of holding devices comprising a holding means, the pressure-sensitive adhesive layer is usually attached to part of the holding means such as, for example, to the rear surface of a one-piece construction type hook or the rear surface of an anchoring device. The thickness of the adhesive layer and its extension in the bonding area are chosen to provide a sufficient holding power for the respective applications.
The pressure-sensitive adhesive layer of the holding device is attached to rigid surfaces.
Examples of rigid surfaces include glass, metal surfaces such as stainless steel and brushed aluminum, wood, painted metal and wood, plastics such as polymethylmethacrylate, polypropylene, melamine-coated chipboard such as that used in countertops, concrete (painted or unpainted) and cinderblock (painted or unpainted). Rigid surfaces which can be bonded, but are somewhat less suitable for use with the holding device of the present invention include wallpaper, sheetrock and such surfaces which delaminate easily after prolonged contact with a strong adhesive bond.
In case of a holding device comprising a holding means, part of the surface of the holding means bears a layer of a pressure-sensitive adhesive which is attached to the rigid surface. The shape of the area of the holding means bearing the pressure-sensitive adhesive is preferably chosen to conform closely to the shape of the area where it is intended to be adhered so that maximum contact and a good adhesive bond will result.
The holding device of the present invention bears a pressure-sensitive adhesive layer selected so that
(i) the pressure-sensitive adhesive layer exhibits a high internal strength,
(ii) the holding device exhibits a high cantilever resistance, and
(iii) the pressure-sensitive adhesive layer can be readily removed from rigid surfaces.
Feature (i) ensures that the pressure-sensitive adhesive does not split apart under the stress of removal or breaks apart in larger adhesive parts only which can be gripped manually.
The cantilever resistance of feature (ii) is defined as ability of the pressure-sensitive adhesive bond to resist failure under forces which occur when, for example, an object is attached to a hook bonded to an essentially vertical surface. The required cantilever resistance depends on the intended application, but it should be high enough to render the holding device suitable for many practical applications such as, for example, mounting a liquid soap dispenser or a dispenser for tissues on ceramic tile walls. Another more demanding application which requires high cantilever resistance is, for example, mounting of wall hooks which are intended to hold heavy and bulky objects such as bathrobes and coats which exert not only great forces in the vertical
3M Innovative Properties Company
Peters Carolyn V.
Truong Duc
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