Note: Descriptions are shown in the official language in which they were submitted.
CA 02769260 2013-04-03
1
Dimensionally stable polyester foil and data carrier having the polyester foil
[00011 The subject matter of the present invention is a foil composite
material
having at least one base layer of a base layer material, which has a first
surface and
a second surface, and having a first cover layer of a first cover layer
material,
which covers the first surface of the base layer. The subject matter of the
present
invention is also a method for manufacturing the foil composite material, as
well as
products manufactured with the foil composite material, such as a card having
an
electronic data carrier, and a method for manufacturing such cards.
[0002] The contactless data transmission is increasingly gaining in
importance,
for example for the marking of goods, for the purposes of merchandise control,
and
in particular also for electronic ID documents. The data carrier here
typically is a
module of IC chip and antenna in the form of an integrated thin-film circuit.
The
chip consists of a plurality of electronic components such as transistors,
capacitors,
resistors, diodes, etc., and the antenna is a conductive layer, typically in a
coil form.
The stored information can be read-out and shown for example on a display or
transmit certain commands. The data carriers are attached on the surface of
objects,
for example integrated in labels, or integrated in the layer structure of a
card with
applications such as ID documents, display cards or in transponder technology.
For
this purpose, the data carriers are enclosed between foils, a carrier foil and
at least
one covering further foil. Carrier foils typically are foils of polyester,
polycarbonates, polyamides, polyimides, and in particular biaxially stretched
foils
like BOPET. Covering foils typically are foils of polyethylene, polypropylene,
polystyrene, polyamides, polycarbonates, polyesters and other thermoplastics.
The
foils are connected by laminating, whereby temperature loads acting on the
foils are
inevitable. If the carrier foil is thereby distorted, disruptions in the
contacting
among the components may occur. In use, such a data carrier card may also be
exposed to high temperatures, for example in a parked car in sunlight.
[0003] Because of the high temperature stability required, as carrier foils
for
electronic components, or also for other elements to be accommodated in a
protected fashion in the layer structure of a card, there are often used
biaxially
CA 02769260 2012-01-26
2
. =
oriented semi-crystalline polyester foils, such as biaxially oriented semi-
crystalline
PET. Such foils are known and available for example under the brand name
Melinex or Mylar. Such foils have the advantage that through the stretching
they
are very dimension-stable and temperature-stable, i.e. the dimensions of the
foils
hardly change even under laminating temperatures. Furthermore, through the
stretching there is achieved a high mechanical stability of the foil.
100041 The biaxially oriented polyester foils, however, also have
disadvantages.
For example, the foils lose their inner strength, when they are manufactured
with
fillers in order to receive opaque foils. In filled foils through the
stretching there
arise micropores in the material which lead to striking material weaknesses,
which
in turn has the effect that these foils have the tendency to so-called
"cohesive
fractures". Furthermore, the foils must not only be mechanically stable and
temperature-stable, but also be able to be laminated well to usual card
materials and
preferably be well printable. The biaxially oriented polyester foils, however,
cannot
be laminated without auxiliary layers, and a printing is only possible after a
preceding priming and/or coating, because the foils normally are
manufacturable
only without the desired and for the printing necessary surface roughness.
Another
disadvantage is that the stretched foils are available only in a limited
number of foil
types and foil thicknesses and that due to their orientation they can only be
incorporated as a core layer in a symmetrical card structure, because
otherwise it
may come to a warping of the card.
[0005] Other foils which often are employed as carrier foils are for example
foils
of polycarbonate which have the disadvantage that they are not very scratch-
resistant, not very dimensionally stable, difficult to process and also
relatively
expensive, and foils of polyvinyl chloride which have the disadvantage that
they
are not dimensionally stable and fracture easily, so that cards manufactured
with
these foils often have to be replaced after a short time.
CA 02769260 2013-04-03
3
[0006] Desirable would be a foil which does not have the above-mentioned
disadvantages of the prior art and is suitable as a carrier foil for
electronic
components and other elements in the layer composite of a card.
100071 It is therefore the object of the present invention to provide a foil
which
avoids the disadvantages of the foils of the prior art to the greatest extent
possible.
[0008] It is in particular the object of the present invention to provide a
foil
material which has an advantageous combination of the following properties:
¨ It should be as dimension-stable and temperature-stable as possible;
¨ it should have a high mechanical stability;
¨ it should not tend to cohesive fracture;
¨ it should be well laminatable with all usual plastic card materials, also
without
the use of auxiliary layers;
¨ it should be well printable, also without print pretreatment;
and
¨ it should be manufacturable in an opaque fashion.
[0009] It is also the object of the present invention to provide a
dimensionally
stable and mechanically stable card, such as a data carrier card, which
contains an
electronic data carrier or another object in a fashion protected against
manipulation.
The card should be manufacturable by means of lamination technology.
[0010] The objects are achieved by the foil composite material, the data
carrier
card and the methods for the manufacturing thereof that are disclosed herein.
CA 02769260 2012-01-26
4
, =
100111 In the simplest embodiment, the foil composite material according to
the
invention has two layers, a base layer of a base layer material and a first
cover layer
of a first cover layer material, whereby the first cover layer covers one of
the
surfaces of the base layer all over. The base layer material is a polybutylene
terephthalate material and the first cover layer material is a polyester
material
different from the base layer material, preferably a co-polyester material,
i.e. a
polyester copolymer.
[0012] According to preferred embodiments, the foil composite material
according to the invention has at least three layers. A foil composite
material with
three layers has, additionally to the base layer and the first cover layer, a
second
cover layer of a second cover layer material, whereby the second cover layer
covers
the other surface of the base layer all over, and whereby the second cover
layer
material is a polyester material different from the base layer material,
preferably a
co-polyester material, i.e. a polyester copolymer. The first and the second
cover
layer material may be the same or different.
[0013] Further embodiments of the foil composite material according to the
invention have between the base layer and the first cover layer at least one
first
intermediate layer of a first intermediate layer material and/or have between
the
base layer and the second cover layer at least one second intermediate layer
of a
second intermediate layer material. The first and/or the second intermediate
layer is
respectively formed all over between the base layer and the first cover layer
or the
second cover layer. The first intermediate layer material is a polyester
material
different from the base layer material and the first cover layer material,
which
contains polybutylene terephthalate (PBT) in a lower quantity than the base
layer
material, but in a higher quantity than the first cover layer material. The
second
intermediate layer material is a polyester material different from the base
layer
material and the second cover layer material, which contains polybutylene
terephthalate (PBT) in a lower quantity than the base layer material, but in a
higher
CA 02769260 2012-01-26
quantity than the second cover layer material. The first and the second
intermediate
layer material may be the same or different.
100141 The foil composite material according to the invention may contain
further intermediate layers, whereby the quantity of PBT in the intermediate
layers
decreases respectively from the base layer to the cover layer.
[0015] The base layer material is a polybutylene terephthalate material. A
polybutylene terephthalate material within the terms of the present invention
is a
material of polymers and, optionally, additives. The polymer portion of the
polybutylene terephthalate material is at least 75 weight per cent, preferably
at least
85 weight per cent, and the portion of polybutylene terephthalate (PBT) of the
polymer is at least 50 weight per cent, preferably 60 to 100 weight per cent,
more
preferred 80 to 100 weight per cent, particularly prefered 100 weight per cent
PBT.
The other polymers, if present, are preferably a polyester and/or copolyester
or a
mixture of polyesters and/or copolyesters different from PBT. Particularly
preferred
is polyethylene terephthalate glycol copolymer (PETG). Attention has to be
paid to
the fact that no polyesters are used which may act as plasticizers. The
polymer
portion may also contain extenders, but preferably no extenders are contained.
[0016] PBT is a semi-crystalline polyester with a balanced combination of
stiffness and strength with at the same time good toughness and high heat
resistance and excellent dimensional stability. In this respect, PBT reaches
the
properties of BOPET foils, in contrast to these, however, without stretching.
Therefore, PBT foils or foils of the above-mentioned polybutylene
terephthalate
material can be provided with additives such as fillers without problems. As
no
stretching needs to take place, there will not occur the micropores arising
upon the
stretching with fillers, nor the associated danger of self-splitting of the
foil, i.e. with
the polybutylene terephthalate material used according to the invention there
is no
danger of cohesive fracture. For this reason, the base layer can be easily
filled with
fillers and thus be manufactured in an opaque fashion.
CA 02769260 2012-01-26
6
. =
[0017] As further additives, besides the fillers, there can also be contained
color
pigments and other usual auxiliary substances such as oxidation stabilizers,
flame
retardants or optical brighteners. Color pigments at the same time can act as
fillers.
Examples of fillers are in particular titanium dioxide (Ti02; white), soot
(black) and
colored pigments such as various metal oxides, metal silicates, metal
sulphates, etc.
[0018] Cover layer materials are laminatable polyester materials, in
particular
laminatable co-polyester, different from the base layer material. As in the
base
layer material, the polymer portion is preferably at least 75 weight per cent,
more
preferred at least 85 weight per cent, remainder usual additives such as
fillers, for
example color pigments, and optional other auxiliary substances such as
oxidation
stabilizers, flame retardants, optical brighteners, etc. A preferred filler is
titanium
dioxide, a white pigment which is preferably used in order to make the foils
opaque.
[0019] The polymer portion in the polyester material may contain extenders,
but
preferably is free from extenders. Preferably, no PBT is contained in the
cover
layer materials and particularly preferably at least 80 weight per cent of the
polymer portion consists of polyethylene terephthalate glycol copolymer
(PETG).
In the most preferred embodiment, the polymer portion consists exclusively
(100
%) of PETG.
[0020] Intermediate layer materials are polyester materials which at least
with
respect to the composition of their polymer portion differ from the
neighboring
layers. They consist of a polyester or of a mixture of polyesters and/or a
copolyester or a mixture of copolyesters, whereby the polymer portion is
preferably
at least 75 weight per cent, particularly preferably at least 85 weight per
cent. There
can be contained usual additives such as fillers and extenders, as they were
mentioned above, whereby extenders are preferably not contained.
[0021] The preferred polyester material for the intermediate layers is a
mixture of
PBT and one or more polyesters and/or copolyesters different therefrom,
whereby
CA 02769260 2012-01-26
7
PETG is preferred. Particularly preferably, the intermediate layers consist of
a
mixture of PBT and PETG, optionally with fillers such as for example pigments,
in
order to achieve opacity or a certain coloring.
[0022] The intermediate layers, if present, establish a transition, in terms
of
material, between the base layer and the cover layers, and thus preferably
consist of
the same polymer materials as the adjacent layers, albeit in accordingly
modified
quantitative portions. I.e., in an intermediate layer between the base layer
and the
cover layer, the PBT content of the intermediate layer is to range between the
PBT
content of the base layer and the PBT content of the cover layer. If for
example the
base layer has 90 weight per cent PBT, and the cover layer has 3 weight per
cent
PBT, the PBT content of the intermediate layer ranges between 3 weight per
cent
and 90 weight per cent.
[0023] In the case of several intermediate layers between the base layer and a
cover layer, the PBT content is to decrease from the base layer to the cover
layer.
The intermediate layers preferably contain 30 to 60 weight per cent PBT,
remainder
PETG, and optionally fillers such as for example titanium dioxide.
[0024] When the base layer, the cover layers and the optional intermediate
layers
contain fillers, then the filler content in the layers preferably ranges
respectively
between approx. 5 to 15 weight per cent.
[0025] The foil composite material according to the invention consists of at
least
two layers, one base layer and one cover layer, but preferably has a cover
layer on
both surfaces of the base layer. Between the base layer and a cover layer, or
between the base layer and both cover layers, there can be respectively
provided an
intermediate layer or also several intermediate layers. If intermediate layers
are
present, their number is preferably the same on both sides of the base layer.
The
foil composite material according to the invention is thus built up
"symmetrically"
or at least "partly symmetrically" with respect to the base layer.
CA 02769260 2012-01-26
8
. =
[0026] "Symmetric" means, the foil composite material is mirror-symmetric
related to the base layer as the plane of symmetry. On both sides of the base
layer
there is the same number of layers, and each layer is identical with its
corresponding mirror layer with respect to thickness and composition.
[0027] "Partly symmetric" means, the foil composite material is mirror-
symmetric with respect to the number of layers on both sides of the base
layer, but
the mirror-symmetric layers differ in their thickness and/or composition
(polymer
material, fillers, etc.).
[0028] The prefered embodiments have three or five layers and are symmetric or
partly symmetric.
[0029] In the particularly preferred embodiment, the base layer consists of
PBT,
if appropriate with a portion of PETG, optionally with fillers, and the two
cover
layers consist of PETG, likewise optionally with fillers.
[0030] In the alternative particularly preferred embodiment, between the base
layer and the cover layers there is respectively provided an intermediate
layer
which consists of PBT and PETG, optionally with fillers. The intermediate
layers
contain less PBT than the base layer. With regard to the composition of the
base
layer and the cover layer, to the five-layered particularly preferred
embodiment
applies the same as to the three-layered particularly preferred embodiment.
[0031] The foil composite material according to the invention has,
particularly in
its preferred embodiments, a number of advantages compared to conventional
foils
used in the prior art as carrier foils for electronic components. Due to the
fact that
the base layer, which represents a significant part of the foil composite
material,
consists of PBT or largely of PBT, the foil composite material as a whole has
a
high dimensional stability and a high mechanical strength. PBT is a semi-
crystalline polyester with a balanced combination of stiffness and strength
with at
the same time good toughness and good stability of shape against heat and
excellent dimensional stability. The cover layers, however, i.e. the outer
layers of
CA 02769260 2012-01-26
9
=
the foil composite material according to the invention, consist of a
laminatable
material, preferably a co-polyester, and in particular of PETG. These outer
layers
impart to the foil composite material optimal lamination properties with all
common card materials (polyvinyl chloride, polycarbonate, chlorinated
polyethylene, acrylonitrile butadiene styrene, polyethylene, polypropylene,
thermoplastic polyurethanes, cycloolefin copolymers, etc.) as well as optimal
printing properties. The outer layers can be laminated without laminating
aids, such
as for example primers, adhesives, other coatings, and be printed without
preceding
priming and/or coating. The foil composite materials do not have to be
stretched,
but can be used in the unstretched state. Thus, there is also no problem with
micropores, as occurs in particular with filled BOPET foils, and the foil
composite
materials can be filled with fillers in one or in several layers of the layer
structure,
without there possibly occurring micropores and thus the danger of splitting
of the
foil in itself (cohesive fracture). Through the high dimensional stability,
which
among other things is very important upon the population with electronic
components so as to ensure their good contact among each another, and through
the
high mechanical strength the foil composite material according to the
invention is
also very suitable as a mechanical stabilizer in and with other card materials
in the
layer structure of a card. Here, the foil composite material needs not to be
incorporated as a core layer in a symmetric structure, but can also be used as
an
outer layer.
[0032] The properties of the foil composite material according to the
invention
can be varied over a broad spectrum. This is possible by changing the recipes
of the
individual layers (type and portions of different polymers, type and portions
of
fillers etc.), the number of layers and changing the individual layer
thicknesses.
[0033] The total thickness of the foil composite material according to the
invention is approx. 20 m to 1000 pm, preferably approx. 40 pm to 700 m,
particularly preferably approx. 80 pm to 500 pm. In a three-layered material
the
base layer constitutes approx. 60 to 90% of the total thickness of the foil,
and in a
CA 02769260 2012-01-26
five-layered material the base layer constitutes approx. 50 to 80% of the
total
thickness of the foil.
[0034] The foil composite materials according to the invention are preferably
manufactured by the coextrusion of the thermoplastic polyesters which are to
form
the individual layers. Suitable extruders are in principle all commonly used
extruders, for example screw-type extruders, such as single-screw extruders or
twin-screw extruders or combinations of both types. Fillers and other
auxiliary
substances can already be added upon the manufacturing of the polymers or
polymer mixtures from which the individual layers are to be manufactured, i.e.
the
polymer feed materials of the respective extruders already contain in this
case the
finished layer materials. The desired additives, however, can also be added
directly
upon the foil extrusion. Exemplary extrusion conditions for a foil composite
material having a base layer of PBT (thickness 80 gm) and two cover layers of
PETG (thickness 10 gm each), respectively with 10 weight per cent titanium
dioxide, are a melting temperature between 250 C and 275 C. By changing the
temperature, the melting viscosity of the individual layers is influenced with
the
aim of achieving substantially matching melting viscosities.
[0035] Alternatively, the individual layers, i.e. base layer, cover layers and
optionally intermediate layers, can be respectively separately extruded and
then
hot-laminated. The lamination conditions are material-dependent, and typical
lamination conditions are for instance temperatures of 120 C to 160 C and a
pressure of 20 to 150 bar.
[0036] The foil composite material according to the invention can be
advantageously integrated as a carrier foil in the layer structure. With
regard to the
type, number and arrangement of the further card layers there are no specific
restrictions. The foil composite material according to the invention can be
laminated without problems with all common card materials and may serve
alternatively as a core layer of the card or as an outer layer of the card. Of
course, a
lamination is only possible with such card materials which are laminatable
CA 02769260 2012-01-26
11
=
themselves. If the card contains for example layers of paper or paperboard,
these
layers must be adhesively bonded.
[0037] In the card the foil composite material may serve as a carrier foil for
different objects, in particular areal objects which are to be accommodated in
a
protected fashion in the layer structure of the card, for example electronic
data
carriers.
[0038] The manufacturing of such a card having objects integrated in a
protected
fashion in the card structure, such as electronic data carriers, is carried
out in such a
way that the carrier foil is populated with the objects and then is laminated
to one
or several further foils, so that the object is enclosed between the carrier
foil and the
further foil or the further foils. Upon populating the carrier foil with the
objects, the
objects typically are adhesively bonded to the carrier foil. Certain objects,
such as
antennas, will be applied in the form of a metallization or printing (e.g.
screen
printing, flexographic printing etc.) of the carrier foil, i.e. for example by
vacuum
vapor deposition.
[0039] Depending on the configuration of the card in the individual case, it
may
be useful to laminate all card layers in one single step with each other, or
to carry
out the lamination in several steps. A lamination in several steps can be
advantageous in particular when objects are to be accommodated not only
between
the foil composite material according to the invention and a further card
foil, but
also between other card foils. For example, such a card may contain further
objects
and/or features, such as security elements in the form of embossed structures,
as
prints or as independent, inserted or adhesively bonded elements, markings,
codings etc., as they are in principle known with respect to their type and
mounting.
For the lamination of the card foils, the standard lamination techniques can
be used,
as they are known to a person skilled in the art. The foil composite material
according to the invention does not require any specific measures upon its
lamination with other card foils. It maintains its shape substantially
unchanged
under lamination conditions, so that contact problems in electronic components
are
CA 02769260 2012-01-26
12
. .
avoided, and can be easily manufactured in an opaque fashion, i.e. with
fillers,
without a possible cohesive fracture of the material having to be feared. The
foil
composite material namely is preferably used in a non-stretched form, and it
also
acts in the non-stretched form, because of its high mechanical strength, as a
mechanically stabilizing element of the card.
100401 In the following the present invention is still further illustrated
with
reference to Figures. It is pointed out that the Figures are not true-to-
proportion. In
addition, it is pointed out that the Figures are only to explain the invention
in more
detail, and are in no way restrictive. The same reference numbers denote the
same
or corresponding elements.
Fig 1 shows a section through a foil composite material having three layers
according to the invention;
Fig 2 shows a section through a foil composite material having five layers
according to the invention, and
Fig 3 shows a section through a card with a foil composite material
according to
the invention as a carrier layer for a data carrier.
[0041] Fig 1 shows an embodiment of a foil composite material 1 according to
the invention with a base layer 2 having a first surface 2' and a second
surface 2".
On the first surface 2' a first cover layer 5 is located, and on the second
surface 2" a
second cover layer 6 is located. The first cover layer 5 and the second cover
layer 6
are the outer layers of the foil composite material 1. They consist for
example of
polyethylene terephthalate glycol copolymer (PETG), and the base layer 2
consists
for example of 60 to 100 weight per cent polybutylene terephthalate (PBT),
remainder optionally PETG. The base layer 2 and/or one or both outer layers
may
contain fillers in order to make the foils opaque, for example 5 to 15 weight
per
cent titanium dioxide.
CA 02769260 2012-01-26
13
=
[0042] In its simplest version (not shown) the foil composite material 1
according to the invention has only one base layer 2 and one cover layer 5.
When
such a foil composite material is integrated in the layer structure of a card,
it is
usually not used as a core layer of the card, but as an outer layer, whereby
the cover
layer 5 is laminated to a further card foil, while the base layer 2 serves as
an outer
layer of the card. Alternatively, it is in principle also possible to use the
cover layer
as an outer layer, or to use the foil composite material 1 having only two
layers as
a core layer of a card, whereby then, however, in most cases lamination aids
must
be used.
[0043] Fig 2 shows a foil composite material 1 having five layers according to
the invention, a base layer 2, a first cover layer 5, a second cover layer 6,
and with a
first intermediate layer 3 between the base layer and the first cover layer 5
and a
second intermediate layer 4 between the base layer 2 and the second cover
layer 6.
The base layer and the two cover layers consist of the same materials as the
base
layer and the two cover layers in the embodiment shown in Fig 1, i.e. 60 to
100
weight per cent PBT, remainder PETG as polymer material of the base layer, and
PETG as polymer material of the cover layers, whereby the layers respectively
may
contain, additionally to the polymer material, 5 to 15 weight per cent
titanium
dioxide (related to the respective total amount of the base layer material or
of the
cover layer material). The first intermediate layer 3 and the second
intermediate
layer 4 likewise consist of polymer material plus optionally 5 to 15 weight
per cent
titanium dioxide, whereby the polymer material in turn consists of 30 to 60
weight
per cent PBT, remainder PETG.
[0044] Fig. 1 and Fig. 2 respectively show symmetric embodiments of the foil
composite material 1 according to the invention. The symmetric embodiments are
preferred, but also other embodiments are within the scope of the present
invention.
For example, the embodiment shown in Fig. 2 may have two intermediate layers
between the base layer 2 and the first cover layer 5 and/or no second
intermediate
layer 4 between the base layer 2 and the second cover layer 6. It is also not
CA 02769260 2012-01-26
14
, =
mandatory, that layers symmetric to each other have the same thickness, as
shown
in Fig 1 and Fig. 2. Rather, for example the two cover layers can be
differently
thick. Alternatively, symmetric layers may differ with respect to their
composition,
for example may contain different portions of PBT and PETG, or may contain
different fillers and/or colored pigments, or alternatively no fillers at all.
These
embodiments, which merely have the same number of layers on both sides of the
base layer, but differ with regard to layer thicknesses and/or composition of
the
layers, are partly symmetric. Partly symmetric embodiments, too, are preferred
embodiments, in particular when they only differ with regard to their content
of
fillers or pigments. These additives only serve to produce opacity or color.
100451 Fig. 3 shows a data carrier card 10 with a foil composite material 1
according to the invention (as represented in Fig. 1 or Fig. 2) in cross-
section. For
the sake of a clearer visibility of the structure, the card foils are
represented in the
unconnected state. The foil composite material is the core foil of the card
and
serves as a carrier layer for an IC chip 11. The foil composite material 1 is
used in
the non-stretched state. The card 10 represented in Fig. 3, moreover, has four
further layers, namely the outer layers 14, 15, and the layers 12 and 13
between the
foil composite material 1 and the outer layer 14 or between the foil composite
material 1 and the outer layer 15. The card foils 12 and 13 respectively have
a
design print layer 16, 17. Suitable are for example opaque foils of
polycarbonate,
polyester, ABS, PVC, polyethylene, polypropylene etc. with a thickness of for
example approx. 100 to 250 gm. The outer layers 14, 15 are preferably
transparent
foils with a slightly smaller thickness, for example 50 to 105 gm. These foils
are to
be transparent, so that the design print thereunder can be recognized, and
resistant
to abrasion and scratching in order to protect the card.
100461 A suitable material is for example PVC. Furthermore, suitable are PVC,
PETG, polycarbonate (PC), ABS or so-called blends of different materials, such
as
PC/PETG, PC/ABS, etc. The outer layers, too, can be provided with additional
CA 02769260 2012-01-26
.
features, for example with security elements or individualization features. In
the
embodiment shown the outer foil 14 has a diffraction structure 18.
[0047] In Fig. 3, the card foils are shown in their state before the
lamination. For
manufacturing the card 10, the foils 1, 12, 13, 14 and 15 are brought together
and
laminated to each other without lamination aids under standard lamination
conditions. The card 10 resulting therefrom is, even under thermal load,
mechanically very stable, durable and does not tend to break.
