Decorative sheet and process for producing the same

Details Decorative sheet and process for producing the same Decorative sheet and process for producing the same

1999-10-19

2002-03-05

Zirker, Daniel (Department: 1771)

Stock material or miscellaneous articles

Web or sheet containing structurally defined element or...

Adhesive outermost layer

C428S306600, C428S315500, C428S542200, C428S542600, C428S913300, C156S077000, C156S078000, C156S079000, C156S083000, C156S273300, C427S373000

Reexamination Certificate

active

06352769

ABSTRACT:

DETAILED DESCRIPTION OF THE INVENTION
1. Field of Utilization in Industry
The present invention relates to a decorative sheet, having irregularities, for decoration or other purposes and a process for producing the same. The decorative sheet of the present invention, by virtue of its three-dimensional decorative effect, can be advantageously used as labels, stickers, emblems, and other similar articles.
2. Prior Art
Various decorative sheets have hitherto been proposed for providing three-dimensional decoration. In most of these decorative sheets, a thermal expandable microcapsule or a similar expandable material is used in areas, of the sheets, to be decorated, and the desired decorative effect is attained as a result of expansion of the microcapsule or the like.
For example, Japanese Patent Unexamined Publication (Kokai) No. 60-246878 discloses a pattern print leather. This pattern print leather is formed by printing a pattern on the surface of a substrate film using a printing ink containing a microcapsule with a foaming agent expandable upon heating. The claimed advantage of this technique is that the need to perform embossing can be eliminated and, at the same time, it is possible to avoid misregistration, between the printed pattern and the concave or convex portions, which unavoidably occurs due to the embossing.
Japanese Patent Unexamined Publication (Kokai) No. 63-273673 discloses a three-dimensional ink comprising a binder, a colorant and a foamed microcapsule. The claimed advantage of this technique is that letters, figures or the like can be provided using the color of the ink per se.
Japanese Patent Unexamined Publication (Kokai) No. 2-295730 discloses a decorative material prepared by forming a film of a resin composition containing not more than 4% by weight, based on the total solid content, of a microcapsule type foaming agent on an opaque substrate and foaming the microcapsule type foaming agent. The claimed advantage of this technique is that the surface of the substrate is dimly seen through the film to impart mohair effect while maintaining the features, such as the three-dimensional decorative effect attained by the foamed film.
Japanese Patent Unexamined Publication (Kokai) No. 3-50274 discloses a foamable ink. This foamable ink is characterized in that ultrafine particles having high thermal conductivity or the like are incorporated into an ink containing microspheres of thermal expandable microcapsules having a particle diameter of 10 to 30 mm. The claimed advantage of this technique is that a three-dimensional image can be readily formed by mere rapid drying utilizing high frequency, resulting in enhanced profitability.
The above and other decorative sheets having irregularities, however, involve problems, to be solved, attributable to the layer construction. Specifically, a decorative sheet
20
of the above conventional type, as shown in
FIG. 1
(cross-sectional view), generally has a layer construction comprising: a substrate
21
; and, provided thereon in the following order, an expandable layer
23
containing a foamable microcapsule
24
, a color layer
22
, and a clear layer
27
or a transparent protective layer. A pressure-sensitive adhesive layer
25
with a release liner
26
is provided on the surface of the substrate
21
remote from the decoration side. According to such a layer construction, however, the color layer
22
and the clear layer
27
, which protect the foamed, expanded layer
23
, have no satisfactory thickness, posing a problem that, despite low cohesive force of the foamed, expanded layer
23
, the decorative sheet
20
in its decorated areas (areas corresponding to the expanded layer), when it undergoes abrasion or impact during use or the like, is cracked or separated from the sheet, resulting in remarkable deterioration in appearance.
Problems to be Solved by Invention
An object of the present invention is to solve the above problems of the prior art and to provide an improved decorative sheet which can offer a three-dimensional decorative effect and is free from creation of defects, such as cracks, or separation of the decorated area from the sheet upon being exposed to abrasion, impact or other conditions.
Another object of the present invention is to provide a process for producing the above improved decorative sheet.
The above and other objects of the present invention will be easily understood from the following detailed description.
Means for Solving the Problems
According to one aspect of the present invention, the above objects can be attained by a decorative sheet having irregularities, comprising; a transparent substrate; and, laminated thereon in the following order, a color layer, an expandable layer, and a pressure-sensitive adhesive layer.
According to another aspect of the present invention, there is provided a process for producing the above decorative sheet having irregularities, comprising the steps of:
successively laminating a color layer and an expandable layer on a transparent substrate and drying the laminate;
applying thereon a pressure-sensitive adhesive layer with a release liner provided on the surface of the pressure-sensitive adhesive layer remote from the substrate and pressing the pressure-sensitive adhesive layer against the underlying layer including the color layer; and heating the whole laminate to foam the expandable layer.
According to the decorative sheet of the present invention, in particular, by virtue of partial provision of the expandable layer, that is, provision of the expandable layer in a pattern form, a three-dimensional decorative effect can be attained, and, in addition, since the color layer and the expandable layer underlies the substrate, inadvertent separation of the decorated area from the decorative sheet can be prevented upon being exposed to unfavorable external action, for example, abrasion or impact conditions.
Further, in the decorative sheet of the present invention, there has not been adopted a structure in which a substrate is disposed below an expandable layer as in the prior art-sheet, however, the substrate itself, if it is positioned above the expandable layer, has a strength sufficient to eliminate a lower support.
EMBODIMENTS OF THE INVENTION
FIG. 2
is a cross-sectional view of one preferred embodiment of the decorative sheet according to the present invention. A decorative sheet
10
, as shown in the drawing, comprises: a transparent substrate
1
; and, laminated thereon in the following order, a color layer
2
, an expandable layer
3
containing a thermal expandable microcapsule
4
, and a pressure-sensitive adhesive layer
5
. A release liner
6
is provided on the surface of the pressure-sensitive adhesive layer
5
remote from the color layer
2
. Further, a clear layer
7
is provided on the surface of the substrate
1
(viewer side of the decorative sheet
10
). The decorative sheet of the present invention will be described in more detail based on this embodiment.
In the decorative sheet having irregularities according to the present invention, the transparent substrate serving as a base of the decorative sheet is not limited so far as it has excellent transparency and good adhesion to the underlying color layer and the clear layer covering the surface of the substrate remote from the expandable layer
3
. Specifically, for the substrate, any material may be suitably selected from transparent, naturally occurring or synthetic substrate materials commonly used in the art. The substrate material, which may be advantageously used, is a resin composition which preferably has a softening point below the thermal expansion temperature of the foaming agent used in the expandable layer. Suitable resin compositions include, for example, resins such as polyvinyl chloride (PVC) and polyurethane. Especially, thin films or sheets of polyvinyl chloride and polyurethane can be advantageously used as the substrate. Although the layer thickness of the substrate is not particularly limited, it is usually about 30 to 400 &mgr;m, preferably about 50 to 300 &mg

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