Stock material or miscellaneous articles – Layer or component removable to expose adhesive – Halogen containing compound
Patent
1993-07-21
1995-05-09
Ahmad, Nasser
Stock material or miscellaneous articles
Layer or component removable to expose adhesive
Halogen containing compound
156 71, 156249, 156344, 206389, 206400, 428219, 428220, 4283211, 428346, 428352, 428354, 428355, 428511, 428514, 4289044, 428906, D21H 2720
Patent
active
054138299
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to wallcovering product that comprises a decorative sheet material which carries a layer of pressure sensitive adhesive and which is supplied in the form of a roll.
Conventional wallcoverings either require wet adhesive to be applied to the back of the sheet material for application to a wall or, in the case of ready pasted products, require application of water. These products are inconvenient to use, since the handling of the paste and brushes or water troughs requires that furniture and preferably also carpets be removed from the vicinity of the walls to which the wallcoverings are being applied.
In addition, wet wallcoverings become soft and present handling difficulties. Stretching of the product can occur and can lead to difficulties in matching the pattern repeat on the walls. Walls with lining paper must be sized with glue or the lining paper must be removed before application of further wallcovering and these tasks are inconvenient and time consuming. Once these types of products are applied to the wall and the adhesive has dried it is, however, rare for the dimensional stability, or rather inherent lack thereof, of paper-based substrates to cause problems on changing humidity.
In order to overcome the above-mentioned problems, it has been proposed to provide wallcovering material with a pressure sensitive adhesive or a heat activatable adhesive already in place so that a roll can be unrolled and immediately applied to a wall surface without wetting being necessary. However, generally wallcoverings comprise cellulosic substrates primarily for reasons of economy and there are difficulties with the dimensional stability of these types of products when in place on a wall due to changing moisture content of the atmosphere, especially when exposed to humid environments such as bathrooms. Dimensional stability is a particular problem when the sheet material comprises an adhesive layer, a substrate layer and a decorative-surface layer, the surface layer being provided on a layer of polymeric material such as for example, PVC, ie, a vinyl wallcovering. This type of wallcovering is described for example, in GB 1264795 and GB 1315114.
The particular difficulty arises with polymeric coated substrates, when the atmosphere becomes humid, because water vapour is transmitted through the polymeric coating into the substrate layer. Although this might not be a problem, if the substrate is wholly non-hydrophilic, for economic reasons it always contains hydrophilic material. As a result the transmitted moisture from the atmosphere will be absorbed by the substrate layer and this will cause expansion which may be considerable. This can then give rise to bubbling of the product on the wall or the edges of adjoining strips can become raised. Also, when the external air temperature rises and relative humidity falls, moisture escapes from the product and can cause the product to shrink due to the fibre shrinkage and so leave gaps between strips, though this is less of a problem than that of expansion.
Various methods have been suggested to overcome the problems of dimensional stability of this type of wallcovering product. One way to overcome the problem of dimensional stability could be to use a substrate which does not include hydrophilic material so that differing humidities will not affect the material. Suitable non-hydrophilic substrates include for example glass fibre and polyester fibres. However, such substrates are very expensive and therefore not preferred.
In DE-A-3741194, in order to avoid formation of creases in the wallcovering, it is suggested to use a substrate which expands relatively little in damp conditions, in addition to using an adhesive in the form of small islands of foam so that expansion and contraction which give dimension changes in the substrate caused by moisture changes in the room, will be diverted in a direction away from the wall surface due to micro expansion between adhesive points. In GB 2117271, "dry-on dry-off" wallcoverings, i.e.
REFERENCES:
patent: 3620366 (1971-11-01), Parkinson
William E. Scott and Stanley Trosset, "The Influence of the Environment on Paper Properties", pp. 89-99, Copyright 1989, Tappi Press.
Brown Kenneth D.
Williams David A.
Ahmad Nasser
Forbo-CP Limited
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