Coating processes – Coating remains adhesive or is intended to be made adhesive – Heat sensitive adhesive
Reexamination Certificate
1998-10-21
2001-01-09
Zirker, Daniel (Department: 1771)
Coating processes
Coating remains adhesive or is intended to be made adhesive
Heat sensitive adhesive
C427S208400, C428S343000, C428S3550BL, C442S150000, C442S151000
Reexamination Certificate
active
06171648
ABSTRACT:
The invention relates to a backing material which has been given a partial self-adhesive treatment on at least one side, having been coated with a self-adhesive composition in the form of geometric structures, to processes for producing the coated backing material and to its use.
The partial coating of backing materials with pressure-sensitive self-adhesive compositions is a known technique, whether the self-adhesive compositions are applied in patterned form, for example by screen printing (DE-C 42 37 252), in which case the domes of adhesive can also differ in their size and/or distribution (EP-B 353 972), or by intaglio printing, in lines which interconnect in the longitudinal and transverse directions (DE-C 43 08 649).
It is also known that backing materials detachable especially without residue can be coated with self-adhesive materials.
DE-A 42 37 252 uses special geometries to achieve the absence of residue.
The doping of partially coated self-adhesive tapes has also been described. US 4,699,792 describes a plaster device of this kind, comprising active substances.
Sheet-like structures which can be redetached without residue are obtainable commercially in block form, inter alia, under the name “tesa Notes”® from Beiersdorf.
As backing materials, numerous materials on a film, foil, woven, knit, nonwoven, gel or foam basis have already been described and are also being employed in practice.
Particular requirements are placed on the backing materials in the medical sector. The materials are required to be compatible with the skin, generally permeable to air and water vapour, and also easy to model and conformable. As a result of these requirements, a very thin or soft backing is frequently preferred. For handling and in use, however, the backing materials are also required to be of sufficient strength and possibly of limited extensibility. Furthermore, the backing material should retain sufficient strength and low extensibility even after becoming wet through.
Specific applications, an example being tapes for functional tape dressings for the prophylaxis and therapy of injuries, disorders and altered states of the locomotor system, require non-elastic backings having high strength in the direction of stress. This is achieved by using wovens, usually of cotton or viscose. Backing materials of this kind, with appropriately high basis weight, are generally costly. High flexibility can be achieved only by means of a woven of relatively low strength. When such a fabric is stressed, however, it generally exhibits a certain degree of extension, which is undesirable for the application.
The advantage of patterned application is that the adhesive materials, given an appropriately porous backing material, are permeable to air and water vapour and, in general, are readily redetachable.
The partial application makes it possible, especially in the case of medical applications, for the transepidermal water loss to be dissipated through regulated channels, and improves the evaporation of perspiration from the skin, especially when the backing materials used are permeable to air and water vapour. This prevents the skin irritations induced by instances of build-up of body fluids. The dissipation channels employed allow such fluids to be conducted away even when a multi-ply dressing is used.
A disadvantage of these products, however, is that if the area covered by the adhesive film, which is impermeable per se, is too large there is a corresponding reduction in the permeability to air and water vapour, and the consumption of adhesive composition rises, and also, if the area covered by the adhesive film is too small, the adhesion properties suffer, i.e. the product is detached too readily from the substrate, in particular from the skin, and especially in the case of heavy, textile backing materials.
In the case of the pressure-sensitive self-adhesive compositions referred to, the compositions may be present in a carrier matrix for the purpose of processing. The term carrier matrix is understood to refer to common organic or inorganic solvents or dispersion media.
Systems without a carrier matrix are referred to as 100% systems and are likewise not unknown. They are processed in the elastic or thermoplastic state. A common mode of processing is that of the hotmelt.
Pressure-sensitive hotmelt adhesive compositions of this kind have also already been described in the prior art. They are based on natural or synthetic rubbers and/or other synthetic polymers.
An advantage of the 100% systems is that they avoid an operation of removing the carrier matrix, i.e. the auxiliary media, thereby raising the productivity of processing and at the same time reducing the expenditure on machinery and the energy costs. In addition, this reduces the occurrence of residues of the carrier matrix, which, in turn, is to the benefit of a reduction in the allergenic potential.
The object of the invention was to provide a backing material which is partially self-adhesive on at least one side and which owing to its treatment, i.e. to the applied form and properties of the adhesive composition, and to the material properties of the backing material, serves a functionally appropriate purpose for various fixings, especially for medical products and, in doing so, offers both functional and economic advantages.
This object is achieved by a backing material which is partially self-adhesive on at least one side, as specified in the main claim. The subclaims relate to advantageous embodiments of the backing material, to processes for producing the backing material, and to particularly advantageous uses.
The invention accordingly provides a backing material with a partial self-adhesive coating on at least one side, the application of the self-adhesive composition taking place in the form of geometric structures. For at least some of the geometric structures the base area by means of which the geometric structures adhere to the backing material lies within the area of projection of the geometric structures which is formed as a consequence of the fact that the geometric structures are projected perpendicularly onto the backing material.
Within the geometric structures, therefore, there is at least one cross-sectional area which is aligned parallel to the backing material and which is greater than the base area, i.e. the area by which the geometric structures are anchored to the backing material.
Suitable backing materials are all rigid and elastic sheet-like structures composed of synthetic and natural raw materials. Preference is given to backing materials which, following the application of the adhesive composition, can be employed in such a way that they fulfil the characteristics of a functional bandage. Examples are textiles such as wovens, knits, lays, nonwovens, laminates, nets, films, foams and papers. In addition, these materials can be pretreated or aftertreated. Common pretreatments are corona and hydrophobicization; customary aftertreatments are calendering, thermal conditioning, laminating, punching and lining.
For the coating of the backing it is possible with advantage to employ thermoplastic hotmelt adhesive compositions based on natural and synthetic rubbers and on other synthetic polymers such as acrylates, methacrylates, polyurethanes, polyolefins, polyvinyl derivatives, polyesters or silicones with corresponding additives such as tackifier resins, plasticizers, stabilizers and other auxiliaries where necessary.
Their softening point should be higher than 50° C., since the temperature of application is generally at least 90° C. and preferably between 120° C. and 150° C., or between 180° C. and 220° C. in the case of silicones. Postcrosslinking by means of UV or electron-beam irradiation may be appropriate, if desired, in order to establish particularly advantageous properties of the hotmelt adhesive composition.
Hotmelt adhesive compositions based on block copolymers, in particular, are notable for their diverse variation options, since the controlled reduction in the glass transition temperature of the self-a
Himmelsbach Peter
Jauchen Peter
Keite-Telgenb{umlaut over (u)}scher Klaus
Lehder Matthias
Beiersdorf AG
Norris McLaughlin & Marcus P.A.
Zirker Daniel
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