Decorative labels and method of their production

A method for the production of environmentally compatible decorative labels, which are produced without using a PVC film, is described. The method involves the application of an embossing film, which is capable of transferring heat, on a substrate comprising a separation paper, an adhesive layer, and a plastic film made of homopolymers or copolymers of ethylene with a crystallite melting point (DIN 53765) of 110.degree. to 120.degree. C., a heat of fusion (DIN 53765) of 125 to 180 J/g, melt index (DIN 53735) of 2.0 to 3.5 g/10 min. The embossing film contains a melt adhesive layer that can be activated at 110.degree. to 230.degree. C. The embossing process takes place at a temperature of 110.degree. to 230.degree. C. under a pressure of 1.0 to 7.0 bar for a period of 3 to 0.3 sec.

BACKGROUND OF THE INVENTION 
The invention concerns, a method for the production of decorative labels 
and the decorative labels themselves, which can be obtained according to 
this method. 
A common method for the production of decorative labels consists of placing 
an embossing film on a substrate, using pressure and/or heat. Here, an 
embossing film capable of transferring heat and containing a carrier 
layer, a separation layer, one or more decorative layers, and a melt 
adhesive layer, is generally first applied on a substrate, which comprises 
a separation paper, an adhesive layer, and a plastic film, in such a way 
that the melt adhesive layer of the embossing film and the plastic film of 
the substrate face one another. 
In a second step, the above combination consisting of an embossing film and 
substrate is embossed with a heated stamp, whose stamp area bears a 
certain motif and exhibits raised edges in comparison to the interior of 
the stamp area and acts on the carrier layer of the embossing film, so 
that within the stamp area, the embossing film and substrate are bonded to 
one another via the melt adhesive layer. The edges of the stamp area act 
simultaneously like a punching line, wherein during the embossing process 
in the area of the edges, the separation layer, decorative layer(s), and 
melt adhesive layer of the embossing film--and the plastic film and 
adhesive layer of the substrate are fused and punched through. 
The carrier layer of the embossing film is subsequently removed, wherein 
the parts of the embossing film that are not bonded to the substrate are 
also removed from it. 
Finally, the parts of the plastic film and the adhesive layer of the 
substrate that lie outside the confines of the stamp motif (stamp area) 
are removed. 
The method of the aforementioned type is, for example, described in U.S. 
Pat. No. 4,581,088. 
The plastic film used in the substrate, as a rule, consists of colored 
polyvinyl chloride (PVC), wherein an aluminum film can also be provided 
between the adhesive film of the substrate and the PVC film. 
A plastic film made of polyvinyl chloride, however is no longer desired 
because of concerns having to do with environmental protection and because 
of health hazards due to plasticizers that are eventually present in the 
polyvinyl chloride or residual monomers of vinyl chloride, so that there 
is an urgent need to replace the PVC film in decorative labels, which are 
frequently handled by children in particular. Here, however, there is a 
problem to the effect that until now, no plastic material is known, aside 
from PVC, that is suitable for the hot embossing process of the 
aforementioned type because of its heat-resistance capability and its melt 
behavior. 
SUMMARY OF THE INVENTION 
The goal of the invention under consideration consists of creating a method 
for the production of decorative labels, which avoids the use of a 
polyvinyl chloride film. Another goal consists of making available 
decorative labels without PVC. 
The aforementioned tasks are solved by a method for the production of 
decorative labels, comprising the following steps: 
a) the application of an embossing film capable of transferring heat and 
containing a carrier layer, a separation layer, one or more decorative 
layers, and a melt adhesive layer, on a substrate comprising a separation 
paper an adhesive layer, and a plastic film, in such a way that the melt 
adhesive layer of the embossing film and the plastic film of the substrate 
face one another (FIG. 1a), 
b) embossing of the above combination of embossing film and substrate with 
a heated stamp, whose stamp area bears a certain motif, exhibiting raised 
edges in comparison to the interior of the stamp area and acting on the 
carrier layer of the embossing film, so that within the stamp area the 
embossing film and the substrate are bonded to one another via the melt 
adhesive layer, and with the separation layer, decorative layer(s), and 
melt adhesive layer of the embossing film, along with the plastic film and 
adhesive layer of the substrate, being fused and punched through in the 
area of the raised edges (FIG. 1b); 
c) removal of the carrier layer of the embossing film and the parts of the 
embossing film that are not bonded to the substrate (FIG. 1c); and 
d) removal of the parts of the plastic film and the adhesive layer of the 
substrate that lie outside the confines of the stamp motif (stamp 
area)(FIG. 1d); 
characterized by the fact that one uses homopolymers or copolymers of 
ethylene, with a crystallite melting point (DIN 53765) of 110.degree. to 
120.degree. C., a heat of fusion (DIN 53765) of 125 to 180 J/g, and a melt 
index (DIN 53735) of 2.0 to 3.5 g/10 min, as a plastic film in the 
substrate; and one selects, for the embossing film, a melt adhesive layer 
that can be heat-activated in the range of 110.degree. to 230.degree. C. 
and carries out the embossing process at a temperature of 110.degree. to 
230.degree. C. under a pressure of 1.0 to 7.0 bar for a period of 3 to 0.3 
sec. The terms DIN and FINAT (below) respectively refer to standardized 
test methods for the determination of specific properties and which are 
well-recognized and well-documented. In particular, DIN 53765 refers to 
DIN test method no 53765 for the testing of plastics and elastomers, 
especially thermal analysis by the DSC method. DIN 53735 refers to DIN 
test method no 53735 for determining melt flow index of thermoplastics.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In a specific embodiment of the method in accordance with the invention, a 
suitable low-density polyethylene (LDPE) is used as a plastic film in the 
substrate. The thickness of the film is hereby preferably 20 to 200 .mu.m. 
Solvent adhesives, aqueous adhesive dispersions, or hot-melt adhesives, 
which are preferably based on poly(meth)acrylates and/or rubber compounds, 
can be used for the adhesive layer in the substrate. The adhesive is 
hereby preferably applied in a quantity of 5 to 25 g/m.sup.2, wherein 15 
to 20 g/m.sup.2 is particularly preferred. The application can take place 
on the entire area or partially by rolling or via a printing process 
(flexographic printing, screen printing). 
Silicone paper is preferably used as the separation paper of the substrate. 
By this, one means, on the one hand, calendered or supercalendered paper, 
which is provided with a silicone layer. On the other hand, the silicone 
paper can also contain combinations of paper, a coating, or a polyethylene 
film, and a silicone layer. 
The silicone paper hereby exhibits, in the most favorable case, a basis 
weight of 50 to 300 g/m.sup.2, a thickness of 50 to 300 .mu.m, and 
separation values (FiNAT FTM3) of 0.05 to 0.5 N/25 mm. FINAT FTM3 refers 
to FINAT test method no. 3 for determining force necessary to separate a 
label coated with an adhesive from the support (protection) material. 
In another specific embodiment of the method in accordance with the 
invention, the plastic film of the substrate is provided with an adhesive 
layer (primer) on one or both sides. The thickness of this adhesive layer 
is hereby preferably 2 to 10 .mu.m. 
In accordance with another specific embodiment, the surface of the plastic 
film of the substrate is pretreated with corona or plasma discharge. 
A polyester film, which preferably has a thickness of 4 to 10 .mu.m, is 
advantageously used as a carrier layer in the embossing film for reasons 
having to do with heat resistance. 
A wax layer, which melts when acted en by heat and makes possible an easy 
separation of the carrier layer of the embossing film, can be used as a 
separation layer in the embossing film. 
The decorative layers in the embossing film comprise nonpigmented 
transparent lacquer layers, pigmented lacquer layers, and or metal layers. 
The individual lacquer layers hereby preferably exhibit a thickness of 0.5 
to 5 .mu.m, whereas the metal layers, which are applied by evaporation or 
by cathode sputtering, preferably have a thickness in the range of 50 nm. 
The individual layers can also be provided with a two- or 
three-dimensional pattern. 
In a specific embodiment, the decorative layers in the embossing film 
comprise a pigmented lacquer layer or metal layer on the side facing the 
melt adhesive layer and a nonpigmented lacquer layer on the side facing 
the separation layer. 
With regard to the sequence of the individual steps of the method, there 
are several variants of the method described above. Thus, for example, in 
step b), the embossing film and substrate are first bonded on an entire 
area via the melt adhesive layer at a temperature of 110.degree. to 
200.degree. C. under a pressure of 1.0 to 5.5 bar for a period of 1 to 
0.01 sec, for example, with the use of a stamp or a pressure roller with a 
smooth surface, before the combination of the embossing film and substrate 
is embossed with a heated stamp. The stamp area bears a certain motif and 
exhibits raised edges in comparison to the interior of the stamp area and 
acts on the carrier layer of the embossing film, so that within the 
embossing area, the separation layer, the decorative layer(s), and the 
melt adhesive layer of the embossing film, along with the plastic film and 
adhesive layer of the substrate, are fused and punched through in the area 
of the raised edges, wherein in step c), the carrier layer of the 
embossing film is removed, and in step d), the parts of the embossing 
film, the plastic film, and the adhesive layer of the substrate that lie 
outside the confines of the stamp motif (stamp area) are removed. 
In order to obtain a decorative label with a particularly good spatial 
effect, the method variant described above can be modified by removing the 
carrier layer of the applied embossing film in step b) after the thermal 
bonding of the entire area of the embossing film and substrate, then 
applying a second embossing film with a different decoration consisting of 
a carrier layer, separation layer, one or more decoration layers, and a 
melt adhesive layer, which can be activated in the range of 110.degree. to 
230.degree. C., on the part of the first embossing film remaining on the 
substrate in such a way that the melt adhesive layer of the second 
embossing film faces the decoration layer(s) of the first embossing film. 
The second embossing layer on the decoration layer(s) of the first 
embossing film is embossed with a stamp whose stamp area exhibits 
area-recessing, outer contour patterns with raised edges at a temperature 
of 110.degree. to 230.degree. C., under a pressure of 1.0 to 7.0 bar for a 
period of 3 to 0.3 sec, so that in the immediate area of the contour 
patterns of the stamp area, the first and second embossing films are 
bonded to one another via the melt adhesive layer. In the area of the 
raised edges, the separation layers, decorative layers, and melt adhesive 
layers of the embossing films, along with the plastic film and adhesive 
layer of the substrate, are fused and punched through. Subsequently, in 
step c), the carrier layer of the second embossing film and the parts of 
the second embossing film that are not bonded to the first embossing film 
are removed from it. Finally, in step d), the parts of the first embossing 
film and the parts of the plastic film and the adhesive film of the 
substrate that lie outside the confines of the stamp motif (stamp area) 
are removed. 
In a special form of the above modified method, using two embossing films, 
one can, during the embossing process in step b), use a stamp whose stamp 
area at the same time contains, in addition to the area-recessing, outer 
contour patterns with raised edges, inner, less raised contour lines so 
that the first and second embossing films are bonded in the area of the 
contour pattern and the contour lines via the melt adhesive layer, but the 
separation layers, decorative layers, and melt adhesive layers of the 
embossing films and the plastic film and the adhesive layer of the 
substrate are fused and punched through only in the area of the raised 
edges of the contour pattern. 
In another refinement of the above modified method, one applies in step d), 
a third embossing film consisting of the carrier layer, separation layer, 
one or more decorative layers, and a melt adhesive layer, which can be 
activated in the range of 110.degree. to 230.degree. C., on the first 
embossing film in such a way that the melt adhesive layer of the third 
embossing film faces the decorative layer(s) of the first embossing film 
with the third embossing film being embossed on the decorative layer(s) of 
the first embossing film at a temperature of 110.degree. to 230.degree. C. 
under a pressure of 1.0 to 7.0 bar for a period of 3 to 0.3 sec with a 
second stamp, whose stamp area contains contour lines that lie inside the 
contour pattern of the first stamp but which are less raised than the 
edges of the first stamp, so that in the area of the inner contour lines 
(stamp area) the first and third embossing films are bonded to one other, 
however without the separation layers, decorative layer, and melt adhesive 
layers of the embossing films and the plastic film and the adhesive layer 
of the substrate being fused and punched through, then with the parts of 
the third embossing film that are not bonded to the first embossing film 
being removed. 
In the embossing processes in accordance with the above method variants, a 
temperature of 150.degree. to 180.degree. C. and a pressure of 2.0 to 4.0 
bar are preferably used for a period of 2 to 0.5 sec. 
The bonding of the entire area of the substrate and the first embossing 
film preferably takes place with the above method variants at a 
temperature of 150.degree.-180.degree. C. under a pressure of 2.0 to 4.0 
bar for a period of 0.6 to 0.02 sec. 
The carrier layer used in the second or third embossing films and the 
decorative layers can have the preferred refinements mentioned in 
connection with the first embossing film. 
The method in accordance With the invention facilitates the production of 
environmentally compatible decorative labels that are free of health 
hazards. This was made possible in particular by combining a homopolymer 
or copolymer of ethylene with special fused-mass and melting point 
characteristics and specifically agreed-on embossing parameters. In this 
way, it was possible to prevent, contrary to existing fears, warping of 
the plastic film during the embossing and the blurring of two- or 
three-dimensional patterns of the decorative layer(s), which made an exact 
contouring impossible. 
The following is an example of the execution of the method in accordance 
with the invention, as well as a decorative label that can be obtained 
with this method. 
EXAMPLE 
A hot embossing film from the Oeser/Goeppingen Company (trade description: 
95323860, sparkling green) was applied on a substrate consisting of a 
supercalendered, silicone-coated separation paper with a basis weight of 
84 g/m.sup.2, a polyacrylate-based adhesive layer with a basis weight of 
20 g/m.sup.2, and a polyethylene film with a thickness of 140 .mu.m, a 
crystallite melting point (DIN 53765) of 116.degree. C., a heat of fusion 
(DIN 53765) of 138 to 146 J/g, and a melt index (DIN 53735) of 2.8 g/10 
min, wherein the surface of the polyethylene was protreated by means of 
corona discharge, then with the hot embossing film being bonded to the 
substrate by means of a heated pressure roller with a smooth surface at a 
temperature of 165.degree. C. under a pressure of 3.0 bar for a period of 
0.05 sec. 
Subsequent to this, the carrier film of the above hot embossing film was 
removed and a second hot embossing film with a different color from 
Kurz/Fuerth Company (trade description: ALFM 18,931, silver) was applied 
on the remaining part of the first embossing film. This second hot 
embossing film was bonded to the first hot embossing film by means of a 
stamp, whose stamp area 
contained the outer, area-recessing contour pattern of a horse's head with 
raised contour edges and inner, less raised contour lines--in the shape, 
for instance, of a horse's mane--at an embossing temperature of 
180.degree. C. under an embossing pressure of 4.0 bar for an embossing 
time of 1.0 sec. At the same time, in the area of the outer contour edges, 
the separation layers, decorative layers, and melt adhesive layers of the 
two embossing films, along with the plastic film and adhesive layer of the 
substrate, were thereby fused and punched through. 
Subsequently, the carrier layer of the second hot embossing film was 
removed, wherein also the parts of the second hot embossing film not 
bonded to the first hot embossing film were removed. Finally, the 
remaining parts of the first hot embossing film, the polyethylene film, 
and the adhesive layer of the substrate still outside the confines of the 
horse's head were removed.