Note: Descriptions are shown in the official language in which they were submitted.
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HEAT-TRANSFER LABEL INCLUDING
NON-WAX RELEASE COATING
BACKGROUND OF THE INVENTION
The present invention relates generally to heat-transfer labels and more
particularly to heat-transfer labels that include a non-wax release layer or a
non-wax
release coating.
Heat-transfer labels are commonly used in the decorating and/or labelling of
commercial articles, such as, and without limitation to, containers for
beverages
(including alcoholic beverages, such as beer), essential oils, detergents,
adverse
chemicals, as well as health and beauty aids. As can readily be appreciated,
heat-
transfer labels are desirably resistant to abrasion and chemical effects in
order to
avoid a loss of label information and desirably possess good adhesion to the
articles
to which they are affixed.
One of the earliest types of heat transfer label is described in U.S. Patent
No.
3,616,015, inventor Kingston, which issued October, 1971. In the
aforementioned
patent, there is disclosed a heat-transfer label comprising a paper sheet or
web, a wax
release layer affixed to the paper sheet, and an ink design layer printed on
the wax
release layer. In the heat-transfer labelling process, the label-carrying web
is subjected
to heat, and the label is pressed onto an article with the ink design layer
making direct
contact with the article. As the paper sheet is subjected to heat, the wax
layer begins
to melt. This enables the paper sheet to be released from the ink design
layer, with a
portion of the wax layer being transferred with the ink design layer onto the
article and
with a portion of the wax layer remaining with the paper sheet. After transfer
of the
design to the article, the paper sheet is immediately removed, leaving the
design firmly
affixed to the article and the wax transferred therewith exposed to the
environment. The
wax layer is thus intended to serve two purposes: (1 ) to provide release of
the ink design
from the web upon application of heat to the web and (2) to form a protective
layer over
the transferred ink design. After transfer of the label to the article, the
transferred wax
release layer is typically subjected to a post-flaming technique which
enhances the
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optical clarity of the wax protective layer (thereby enabling the ink design
layer
therebeneath to be better observed) and which enhances the protective
properties
of the transferred wax release.
Many heat-transfer labels include, in addition to the layers described above,
an adhesive layer (comprising, for example, a polyamide or polyester adhesive)
deposited over the ink design to facilitate adhesion of the label onto a
receiving
article, An example of a heat-transfer label having an adhesive layer is
disclosed in
U.S. Patent No. 4,548,857, inventor Galante, which issued October 22, 1985.
Additionally, many heat-transfer labels additionally include a protective
lacquer layer
interposed between the wax release layer and the ink layer. An example of such
a
label is disclosed in U.S. Patent No. 4,426,422, inventor Daniels, which
issued
January 17, 1984.
One phenomenon that has been noted with heat-transfer labels of the type
described above containing a wax release layer is that, quite often, a degree
of
hazing or a "halo" is noticeable over the transferred label when the transfer
is made
onto clear materials. This "halo" effect, which persists despite post-flaming
and which
may detract from the appearance of the label, is caused by the presence of the
wax
coating around the outer borders of the transferred ink design layer. Hazing
due to
the wax release layer may also appear in "open-copy" areas of the label, i.e.,
areas
of the label where no ink is present between the adhesive and protective
lacquer
layers, and also may detract from the appearance of the label.
In addition to and related to the aforementioned problem of hazing, when heat-
transfer labels of the type described above are applied to dark-colored
containers, the
outer wax layer of the label often appears as a whitish coating on the
container,
which effect is undesirable in many instances. Furthermore, scratches and
similar
abrasions to the outer wax layer of the label can occur easily and are readily
detectable.
Accordingly, to address the aforementioned issues, considerable effort has
been expended in replacing or obviating the need for a wax release layer. One
such
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approach to this problem is disclosed in U.S. Patent No. 3,922,435, inventor
Asnes;
which issued November 25, 1975. In the aforementioned Asnes patent, which
relates
to a heat-transfer label for objects such as plastic bottles, the customary
release layer
of wax is replaced with a release layer of a non-wax resin. This non-wax
resinous
layer is referred to in the Asnes patent as a dry release since it does not
transfer to
the article along with the ink design layer and is said to comprise a
thermoset
polymeric resin, such as cross-linked resins selected from the group
consisting of
acrylic resins, polyamide resins, polyester resins, vinyl resins, epoxy
resins, epoxy-
acrylate resins, allyl resins, aldehyde resins, such as phenol-formaldehyde
resins and
the amino-aldehyde resins, e.g., urea formaldehyde or melamine formaldehyde,
and
combinations thereof.
The heat-transfer label of the foregoing Asnes patent also comprises a clear
lacquer layer which is printed onto the release layer, a design print (which
may
include a number of ink layers) which is printed onto the clear lacquer layer,
and a
heat-activatable adhesive layer which is printed onto the design print and the
clear
lacquer layer. The Asnes patent explicitly teaches that "the design print and
the
adhesive print are both located marginally wholly within the lacquer print.
The
adhesive layer may be of the same area or larger in area than the design print
so
long as it is smaller in area than the lacquer print." The Asnes patent also
teaches
that "it is highly preferred that neither the release layer nor the lacquer
layer, at least
where they are in contact with each other, contain any substance which is oily
or
liquid at heat transfer temperature since the oil or liquid, like the wax in
wax release
layers, will part, leaving some on the lacquer surface and some on the removed
release surface."
Another example of a heat-transfer label comprising a non-wax release layer is
disclosed in U.S. Patent No. 4,935,300, inventors Parker et al., which issued
June 19,1990.
In the aforementioned Parker patent, the label, which is said to be
particularly well-suited for
use on high density polyethylene, polypropylene, polystyrene,
polyvinylchloride and
polyethylene terephthalate surfaces or containers, comprises a paper carrier
web which is
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overcoated with a layer of thermoplastic polyethylene. A protective lacquer
layer
comprising a polyester resin and a relatively small amount of a nondrying oil
is printed
onto the polyethylene layer. An ink design layer comprising a resinous binder
base
selected from the group consisting of polyvinylchloride, acrylics, polyamides
and
nitrocellulose is then printed onto the protective lacquer layer. A heat-
activatable
adhesive layer comprising a thermoplastic polyamide adhesive is then printed
onto
the ink design layer.
Although the above-described Parker label substantially reduces the wax-
related effects discussed previously, said label does not quite possess the
same
release characteristics of heat-transfer labels containing a wax release
layer. In fact,
when put to commercial use, the polyethylene release layer of the Parker label
was
found to become adhesive when subjected to the types of elevated temperatures
typically encountered during label transfer. Accordingly, anothertype of heat-
transfer
label differs from the Parker heat-transfer label in that a very thin layer or
"skim coat"
of carnauba wax is interposed between the polyethylene release layer and the
protective lacquer layer to improve the release of the protective lacquer from
the
polyethylene-coated carrier web. The thickness of the skim coat corresponds to
approximately 0.1-0.4 Ibs. of the wax spread onto about 3000 square feet of
the
polyethylene release layer. The aforementioned "skim coat-containing" heat-
transfer
label also differs from the Parker label in that the heat-activatable adhesive
of the
"skim coat" label is printed over the entirety of the ink and protective
lacquer layers,
with the peripheral edges of the adhesive layer in direct contact with the wax
skim
coat.
An example of a "skim coat-containing" heat-transfer label of the type
described
above is disclosed in U.S. Patent No. 5,800,656, inventors Geurtsen et al.,
which issued
September 1, 1998. According to one embodiment, the Geurtsen label is designed
for use
on silane-treated glass containers of the type that are subjected to
pasteurization
conditions, the label including a support portion, a skim coat positioned on
top of the
support portion and a transfer portion positioned on top of the support
portion. The support
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portion includes a sheet of paper overcoated with a release layer of
polyethylene.
The transfer portion includes an organic solvent-soluble phenoxy resin
protective
lacquer layer, an organic solvent-soluble polyester resin ink layer over the
protective
lacquer layer, and a water-dispersible acrylic adhesive resin layer over the
ink and
protective lacquer layers and onto a surrounding portion of the skim coat.
Although the release properties of heat-transfer labels that include the
aforementioned wax skim coat are much improved compared to similar heat-
transfer
labels lacking said wax skim coat, said labels do result in a portion of the
wax skim
coat being transferred to the article being decorated during label transfer.
As a result,
particularly when the labelled article is dark in color, a wax residue is
often visible to
the naked eye on the article around the peripheries of the label and in open-
copy
areas of the label. Such a wax residue, for the reasons discussed above, is
undesirable from an aesthetic standpoint. In addition, said wax residue
precludes the
possibility of decorating articles, such as containers, with "wrap-around"
labels of the
type that completely encircle an object since the adhesive present at the
trailing end
of the label will not adhere to that portion of the article covered by the wax
residue
that is deposited with the leading end of the label.
Heat-transfer labels of the type that include the aforementioned wax skim coat
are typically heated during the labelling process in order to cause the wax
skim coat
to soften, thereby facilitating label transfer. However, the heating
temperatures
needed to soften the wax skim coat have become increasingly more difficult to
achieve as new decorating systems are being developed in which bottle
throughput
is higher and, consequently, the dwell time for heating is shorter, and the
actual
heating temperatures are lower.
Yet another example of a heat-transfer label comprising a non-wax release
layer is
disclosed in PCT Appln. No. PCT/US89/01731, inventors Abber et al., which was
published
February 8, 1990. In the aforementioned Abber PCT application, a heat-transfer
label for
application to a plastic bottle or container is described that includes a
carver sheet and a
transferable substrate affixed to the carrier sheet. The carrier sheet
includes a nonwax thermoset
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release layer coated over a paper sheet. The nonwax thermoset release layer is
a
noncellulosic alkyd resin formed by the crosslinking of an alkyd polymer with
a
methoxy melamine to produce a thermoset release. The alkyd polymer employed is
preferably of the type formed by the thermosetting reaction product of a
hydroxy-
functional polyester with a drying oil. The transferable substrate affixed to
the carrier
sheet includes a nonwax lacquer transfer layer, an ink design layer over the
lacquer
transfer )ayer and a heat-activatable adhesive layer over the ink design
layer.
Still another example of a heat-transfer label comprising a non-wax release
layer is disclosed in PCT Appln. No. PCTIEP97/00642, inventors Ast, which was
published on August 14, 1997. In the aforementioned Ast PCT application, the
release
layer is made of polypropylene or polyethylene.
Still yet another example of a heat-transfer label comprising a non-wax
release
layer is disclosed in European Patent Appln. No. 824,251, inventors Brandt et
al., which
was published on February 18, 1998. In the aforementioned Brandt EPO
application,
there is disclosed a heat-transfer label that is designed for use on a crate
and that, once
applied to a crate, can easily be removed therefrom in a washing process
without the ink
dissolving in the wash liquid. The foregoing Brandt label comprises a backing
layer and
a transfer layer, the transfer layer being releasably attached to the backing
layer. The
backing layer comprises a polypropylene film coated with a silicone layer. The
transfer
layer comprises a first containment layer in contact with the silicone layer,
an ink layer
on top of the first containment layer and marginally wholly within the first
containment
layer, a second containment layer on top of the ink layer and on top of the
first
containment layer, the first and second containment layers contacting one
another
outside the perimeter of the ink layer to form a closed envelope around the
ink layer,
and an adhesive layer on top of the first and second containment layers, the
first
containment layer and the adhesive layer contacting one another outside the
perimeter
of the second containment layer to form a closed envelope around the ink layer
and
second containment layer.
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Unfortunately, the use of :silicone as a release coating, as in the preceding
example, presents certain proble ~ns or shortcomings. One of these problems is
the
difficulty of printing a label on a silicone release. Other possible problems
or
shortcomings are set forth in U.3. Patent No. 5,314,929, inventors Crivello et
al.,
which issued May 24, 1994. In them aforementioned Crivello patent, there is
disclosed a
silicone-free release coating composition adapted for use with adhesive tapes,
said
silicone-free coating composition being said to be rapidly curable and
comprising (a)
between about 50 and about 95 wt % of an alkyl vinyl ether monomer having the
formula
C~Hz~+~O-CH-CH2 wherein n has a value of from 8 to 20, optionally containing a
cationically polymerizable comonomer; (b) between about 5 and about 50 wt % of
a
multifunctional vinyl ether monomer and (c) between about 0.1 and about 10 wt
% of an
opium salt photoinitiator.
It is to be noted that the aforementioned Crivello patent neither teaches nor
suggests the use of its release composition as a release coating in a heat-
transfer label.
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SUMMARY OF THE INVENTION
It is an object of the present invention to provide a heat-transfer label that
includes a novel release layer or release coating.
It is another object of the present invention to provide a heat-transfer label
as
described above whose release layer or release coating overcomes at least some
of
the problems associated with many of the heat-transfer label release layers or
coatings described above.
It is still another object of the present invention to provide a heat-transfer
label
as described above whose release layer or release coating does not transfer,
to any
discernible degree observable to the naked eye, with the transfer portion of
the label
onto the article that is being labelled.
In furtherance of the above and other objects to be set forth or to become
apparent from the description to follow, and according to one aspect of the
invention,
there is provided a heat-transfer label, said heat-transfer label comprising:
(a) a transfer portion, said transfer portion comprising
(i) an ink design layer, and
(ii) a heat-activatable adhesive layer over said ink design layer;
and
(b) a support portion, said transfer portion being positioned over said
support portion for transfer ofthe transfer portion from the support portion
to an article
under conditions of heat and pressure, said support portion comprising
(i) a carrier, and
(ii) a release coating positioned over said carrier, said release
coating being made of a non-wax, non-silicone, thermoset release material,
said
release coating separating cleanly from said transfer portion with no visually
discernible portion of said release coating being transferred to the article
along with
said transfer portion, said release coating having a total surface energy of
about 25
to 35 mN/m (preferably about 30 mN/m), of which about 0.1 to 4 mN/m
(preferably
about 1.3 mN/m) is polar surface energy.
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Said release coating preferably has a thickness of about 0.01 to 10 microns,
more preferably about 0.02 tot micron, even more preferably about 0.1 micron.
In
addition, when analyzed by XPS (X-ray photoelectron spectroscopy), said
coating
preferably has a carbon content (by atomic %) of about 90 to 99.9% (preferably
about
97%) and an oxygen content (by atomic %) of about 0.1 to 10% (preferably about
3%). Accordingly, said coating is predominantly a hydrocarbon in terms of its
chemical makeup.
An example of the present support portion is a coated film structure
preferably
comprising:
(i) polymers selected from the group consisting of polyesters such as
polyethylene terephthalate, polyethylene napthylene; polyolefins such as
polyethylene and polypropylene; and polyamides; wherein said polymers form a
polymeric film surface; and
(ii) a primer coating comprising:
(A) functionalized a-olefin containing copolymers, preferably acid
functionalized a-olefin containing copolymers, selected from the group
consisting of
ethylene/acrylic acid copolymers; ethylene/methacrylic acid copolymers;
ethylene/vinylacetate/acrylic acid terpolymers; ethylene/methacrylamide
copolymers;
ethylene/glycidyl methacrylate copolymers; ethylene/dimethylaminoethyl
methacrylate
copolymers; ethylene/2-hydroxyethyl acrylate copolymers; propylene/acrylic
acid
copolymers; etc. and
(B) crosslinking agents selected from the group consisting of amino
formaldehyde resins, polyvalent metal salts, isocyanates, blocked isocyanates,
epoxy
resins and polyfunctional aziridines;
(iii) wherein said primer coating is applied as a primer to the polymeric film
surface, preferably in its amorphous or semi-oriented state and reacted with
newly
generated polymeric film surfaces formed during uniaxial or biaxial stretching
and
heat setting.
Preferably, the above-mentioned transfer portion further comprises a
protective lacquer layer, said ink design layer being positioned over said
protective
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lacquer layer, said heat-activatable adhesive layer extending beyond the
peripheries
of said ink design layer and said protective lacquer layer. The release layer
of the
aforementioned support portion is preferably in direct contact with the
transfer portion
thereof; more preferably, the release layer is in direct contact with each of
the
protective lacquer layer and the periphery of the heat-activatable adhesive
layer.
The heat-activatable adhesive layer of the foregoing heat-transfer label
preferably comprises a polyester resin and more preferably additionally
comprises an
anti-blocking agent, such as a paraffinic wax. The protective lacquer layer of
the
foregoing heat-transfer label preferably comprises a phenoxy resin, more
preferably
a cross-linked phenoxy resin. The ink design layer of the foregoing heat-
transfer
label preferably comprises a polyester resin.
According to another aspect of the invention, there is provided a heat-
transfer
label comprising:
(a) a transfer portion, said transfer portion comprising
(i) an ink design layer, and
(ii) a heat-activatable adhesive layer over said ink design layer;
and (b) a support portion, said transfer portion being positioned over said
support
portion for transfer of the transfer portion from the support portion to an
article under
conditions of heat and pressure, said support portion comprising
(i) a carrier, and
(ii) a release coating positioned over said carrier, said release
coating being made of a non-wax, non-silicone, thermoset release material,
said
release coating separating cleanly from said transfer portion with no visually
discernible portion of said release coating being transferred to the article
along with
said transfer portion, said release coating having a carbon content (by atomic
%) of
about 90 to 99.9% (preferably about 97%) and an oxygen content (by atomic %)
of
about 0.1 to 10% (preferably about 3%), as measured by X-ray photoelectron
spectroscopy.
The present invention is also directed to a method of decorating an article,
such as a clear glass container, said method comprising in one aspect the
steps of:
WO 01/03950 CA 02378656 2002-O1-08 PCT/[JS00/177~3
(a) providing a heat-transfer label, said heat-transfer label comprising:
(i) a transfer portion, said transfer portion comprising
(A) an ink design layer, and
(B) a heat-activatable adhesive layer over said ink design
layer, and
(ii) a support portion, said transfer portion being positioned over
said support portion for transfer of the transfer portion from the support
portion to a
glass article under conditions of heat and pressure, said support portion
comprising
(A) a carrier, and
(B) a release layer positioned over said carrier, said
release layer being made of a non-wax, non-silicone, thermoset release
material, said
release layer separating cleanly from said transfer portion with no visually
discernible
portion of said release layer being transferred to the glass article along
with said
transfer portion, said release layer having a total surface energy of about 25
to 35
mN/m (preferably about 30 mN/m), of which about 0.1 to 4 mN/m (preferably
about
1.3 mN/m) is polar surface energy; and
(b) transferring said transfer portion from said support portion onto the
article.
Said release coating preferably has a thickness of about 0.01 to 10 microns,
more preferably about 0.02 tot micron, even more preferably about 0.1 micron.
In
addition, when analyzed by XPS (X-ray photoelectron spectroscopy), said
coating
preferably has a carbon content (by atomic %) of about 90 to 99.9% (preferably
about
97%) and an oxygen content (by atomic %) of about 0.1 to 10% (preferably about
3%). Accordingly, said coating is predominantly a hydrocarbon in terms of its
chemical makeup.
An example of the present support portion is the above-described coated film
structure.
The present invention is also directed to a method of decorating an article,
such as a clear glass container, said method comprising in another aspect the
steps
of:
(a) providing a heat-transfer label, said heat-transfer label comprising:
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(i) a transfer portion, said transfer portion comprising
(A) an ink design layer, and
(B) a heat-activatable adhesive layer over said ink design
layer, and
(ii) a support portion, said transfer portion being positioned over
said support portion for transfer of the transfer portion from the support
portion to a
glass article under conditions of heat and pressure, said support portion
comprising
(A) a carrier, and
(B) a release layer positioned over said carrier, said
release layer being made of a non-wax, non-silicone, thermoset release
material, said
release layer separating cleanly from said transfer portion with no visually
discernible
portion of said release layer being transferred to the glass article along
with said
transfer portion, said release layer having a carbon content (by atomic %) of
about
90 to 99.9% (preferably about 97%) and an oxygen content (by atomic %) of
about
0.1 to 10% (preferably about 3%), as measured by X-ray photoelectron
spectroscopy;
and
(b) transferring said transfer portion from said support portion onto the
article.
The present invention is also directed to a transfer label, said transfer
label
differing from the above-described heat-transfer label in that a pressure-
sensitive
adhesive is used in place of the above-described heat-activatable adhesive.
For purposes ofthe present specification and claims, it is to be understood
that
certain terms used herein, such as "on" or "over," when used to denote the
relative
positions of two or more layers of a heat-transfer label, are primarily used
to denote
such relative positions in the context of how those layers are situated prior
to transfer
of the transfer portion of the label to an article since, after transfer, the
arrangement
of layers is inverted as those layers which were furthest removed from the
associated
support sheet are now closest to the labelled article.
Additional objects, as well as features, advantages and aspects of the present
invention, will be set forth in part in the description which follows, and in
part will be
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obvious from the description or may be learned by practice of the invention.
In the
description, reference is made to the accompanying drawings which form a part
thereof and in which is shown by way of illustration specific embodiments for
practicing the invention. These embodiments will be described in sufficient
detail to
enable those skilled in the art to practice the invention, and it is to be
understood that
other embodiments may be utilized and that structural changes may be made
without
departing from the scope of the invention. The following detailed description
is,
therefore, not to be taken in a limiting sense, and the scope of the present
invention
is best defined by the appended claims.
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BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are hereby incorporated into and
constitute a part of this specification, illustrate preferred embodiments
ofthe invention
and, together with the description, serve to explain the principles of the
invention. In
the drawings wherein like reference numerals represent like parts:
Fig. 1 is a schematic section view of one embodiment of a heat-transfer label
constructed according to the teachings of the present invention;
Fig. 2 is a graph depicting the release values obtained in Example 2;
Fig. 3 is a graph depicting the release values obtained in Example 3;
Fig. 4 is a graph depicting the release values obtained in Example 4;
Fig. 5 is a graph depicting the surface oxygen content values obtained by X-
ray photoelectron spectroscopy (XPS) in Example 5;
Fig. 6 is a graph depicting the release values obtained in Example 6; and
Fig. 7 is a graph depicting the surface oxygen content values obtained by X-
ray photoelectron spectroscopy (XPS) in Example 7.
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DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring now to Fig. 1, there is shown a schematic section view of one
embodiment of a heat-transfer label constructed according to the teachings of
the
present invention, said heat-transfer label being represented generally by
reference
numeral11.
Label 11 comprises a support portion 13. Support portion 13, in turn,
comprises a carrier 15. Carrier 15 preferably is a polymeric film selected
from the
group consisting of polyesters, such as polyethylene terephthalate,
polyethylene
napthylene; polyolefins, such as polyethylene and polypropylene; and
polyamides.
More preferably, carrier 15 is a clear plastic film of the type described
above.
As can readily be appreciated, one benefit to using a clear material as
carrier 15 is
that, if desired, one can inspect the quality of the printed matter of the
label by looking
at said printed matter through carrier 15 (from which perspective said printed
matter
appears as it will on the labelled article), as opposed to looking at said
printed matter
through the adhesive layer of the label (from which perspective said printed
matter
appears as the mirror image of what will appear on the labelled article).
A particularly preferred plastic material for use as carrier 15 is a clear
polyester
film, such as a clear polyethylene terephthalate (PET) film. This is because,
at least
as compared to some other plastic materials like polyethylene and
polypropylene,
polyester is a strong plastic material and makes a good substrate to be
printed onto.
In addition, unlike polyethylene, polyester does not tend to soften and become
tacky
at the types of temperatures typically encountered during heat-transfer.
Typically,
carrier 15 has a thickness of about 1-2 mil.
Support 13 also includes a release layer or coating 17, coating 17 preferably
being applied directly on top of carrier 15. Coating 17 is a thermoset release
material that separates cleanly from the below-described transfer portion of
label 11
and is not transferred, to any visually discernible degree, with said transfer
portion of
label 11 onto an article being labeled. (For purposes of the present
specification and
claims, the term "visually discernible" is to be construed in terms of an
unaided or
CA 02378656 2004-O1-22
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naked human eye.) Preferably, release coating 17 is clear for the same types
of
reasons given above in connection with carrier 15.
Coating 17 does not contain any waxes or any silicones, except to the limited
extent provided below, and the terms "non-wax" and "non-silicone," when used
in the
present specification and claims to describe and to define the present release
layer
or coating, are defined herein to exclude from said release layer or coating
the
presence of any and all waxes and silicones not encompassed by the limited
exceptions provided below.
Coating 17 preferably has a thickness of about 0.01 to 10 microns, more
preferably about 0.02 tot micron, even more preferably about 0.1 micron. In
addition,
coating 17 preferably has a total surface energy of about 25 to 35 mN/m
(preferably
about 30 mN/m), of which about 0.1 to 4 mN/m (preferably about 1.3 mN/m) is
polar
surface energy. Furthermore, when analyzed by XPS (X-ray photoelectron
spectroscopy), coating 17 preferably has a carbon content (by atomic %) of
about 90
to 99.9% (preferably about 97%) and an oxygen content (by atomic %) of about
0.1
to 10% (preferably about 3%). Accordingly, coating 17 is predominantly a
hydrocarbon in its chemical makeup.
An example of a coated polymer film suitable for use as support 13 of the
present invention is available from DuPont Corp. (Wilmington, DE) as product
number
140AXM 701 (140 gauge coated polyester film). Other coated polymer films which
may be used as support 13 are described in European Patent Application No.
819,726, published January 21, 1998. The aforementioned European patent
application
teaches a coated film structure preferably comprising:
(i) polymers selected from the group consisting of polyesters such as
polyethylene terephthalate, polyethylene napthylene; polyolefins such as
polyethylene and polypropylene; and polyamides; wherein said polymers form a
polymeric film surface; and
(ii) a primer coating comprising:
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WO 01/03950 CA 02378656 2002-O1-08 PCT/US~O/17703
(A) functionalized a-olefin containing copolymers, preferably acid
functionalized a-olefin containing copolymers, selected from the group
consisting of
ethylene/acrylic acid copolymers; ethylene/methacrylic acid copolymers;
ethylene/vinylacetate/acrylic acid terpolymers; ethylene/methacrylamide
copolymers;
ethylene/glycidyl methacrylate copolymers; ethylene/dimethylaminoethyl
methacrylate
copolymers; ethylene/2-hydroxyethyl acrylate copolymers; propylene/acrylic
acid
copolymers; etc. and
(B) crosslinking agents selected from the group consisting of amino
formaldehyde resins, polyvalent metal salts, isocyanates, blocked isocyanates,
epoxy
resins and polyfunctional aziridines;
(iii) wherein said primer coating is applied as a primer to the polymeric film
surface, preferably in its amorphous or semi-oriented state and reacted with
newly
generated polymeric film surfaces formed during uniaxial or biaxial stretching
and
heat setting.
Although the above-described polymeric film surface is preferably formed of
a polyester, a polyolefin, or a polyamide, it may be formed form any material
capable
of being formed into a sheet or film. The polymeric film surface should be
capable
of binding or reacting with an acid-functionalized a-olefin copolymer to form
a
modified film base.
The above-mentioned polymer films can be manufactured by an extrusion
process, such as a cast film or blown film process. In a cast film process,
the polymer
resin is first heated to a molten state and then extruded through a wide slot
die in the
form of an amorphous sheet. The sheet-like extrudate is rapidly cooled or
"quenched" to form a cast sheet of polyester by contacting and traveling
partially
around a polished, revolving casting drum. Alternatively, the extrudate can be
blown
in a conventional blown film process. Regardless of the process, however, the
polyester sheet is preferably uniaxially or biaxially (preferably biaxially)
stretched in
the direction of film travel (machine direction) and/or perpendicular to the
machine
direction (traverse direction), while being heated to a temperature in the
range of from
about 80°C to 160°C, preferably about 90°C to
110°C, the degree of stretching may
17
CA 02378656 2004-O1-22
WO 01/03950 PCTlUS00117703
range from 3.0 to 5.0 times the original cast sheet unit dimension, preferably
from
about 3.2 to about 4.2 times the original cast sheet dimension. Reaction with
the
newly generated polymer film surfaces formed during stretching preferably
occurs at
temperatures about 130°C or higher,
Additives such as coating aids, wetting aids such as surfactants (including
silicone surfactants), slip additives, antistatic agents can be incorporated
into the
primer coating in levels from 0 to 50% based on the total weight of additive-
free
coating solids.
The above-described primer coating may additionally be applied to the bottom
surface of the polymeric film for use in preventing the adhesive layer of a
transfer
portion from adhering to the underside of carrier 15 when a label assembly
comprising a plurality of transfer portions on a single support portion13 is
wound into
a roll.
Label 11 further comprises a transfer portion 21 (it being understood that a
plurality of transfer portions 21 may be spaced apart on a single support
portion 13).
Transfer portion 21, in turn, preferably includes (i) a protective lacquer
layer 23
printed directly on top of a desired area of release layer 17, (ii) an ink
design layer 25
printed directly onto a desired area of lacquer layer 23, and (iii) a heat-
activatable
adhesive layer 27 printed directly onto ink design layer 25, any exposed
portions of
lacquer layer 23 and a surrounding area of release layer 17.
Where the article being labeled is a glass article, such as a silane-treated
glass container, protective lacquer layer 23 preferably is a phenoxy
protective lacquer
layer, such as that described in U.S. Patent tJo. 5,800,656, or is a cross-
linked
phenoxy lacquer layer such as that disclosed in U.S. Patent No. 6,033,763.
This is
because phenoxy protective lacquer layers tend to possess the high degree of
scuff
resistance and chemical resistance preferred for glass articles. It should be
understood,
however, that release layer 17 releases well from a variety of protective
lacquer layers
of different compositions and that other types of protective lacquer resins
may also be
18
W~ 01/03950 CA 02378656 2002-O1-08 pCT/US00/17703
suitable for use in layer 23 depending upon the type of article being labeled
and the
use to which the decorated article is to be put.
Examples of phenoxy lacquer resins suitable for use in the aforementioned
phenoxy or cross-linked phenoxy protective lacquer layer include the PAPHEN
Phenoxy Resins (Phenoxy Specialties, Rock Hill, SC - a division of InChem
Corp.),
which have the following chemical structure:
~~3 H H N
o ~-a-0_ ~_ C _ C
cH3 N oN H
r~= sz -~ X23.
A particularly preferred PAPHEN Phenoxy Resin is PKHH, a medium weight grade
of the above structure which, at 40% solids, by weight, in methyl ethyl ketone
(MEK),
has a solution viscosity of 4500 to 7000 mPa~s(cP). Examples of a suitable
cross-
linker for cross-linking the aforementioned phenoxy resin include partially
methylated
melamine-formaldehyde resins of the type present in the CYMEL 300 series of
partially methylated melamine-formaldehyde resin solutions (Cytec, Industries,
Inc.,
West Paterson, NJ) and, in particular, CYMEL 370 partially methylated melamine-
formaldehyde resin solution (8812% nonvolatiles, iBuOH solvent). Preferably,
the
solids of the aforementioned CYMEL 370 resin solution constitute no more than
about 5%, by weight, of lacquer layer 23 (with the remainder of lacquer layer
23 being
the aforementioned phenoxy resin) since amounts of CYMEL 370 in excess thereof
may cause lacquer layer 23 to become tacky.
To form a cross-linked phenoxy lacquer layer 23, a lacquer composition
comprising the above-identified phenoxy lacquer resin, a suitable cross-linker
and
one or more suitable volatile solvents are deposited onto a desired area of
release
layer 17, preferably by gravure printing or a similar technique. After
deposition of the
lacquer composition onto the desired area of layer 17, the volatile solvents)
evaporate(s), leaving only the non-volatile components thereof to make up
lacquer
layer 23. In a preferred embodiment, the lacquer composition comprises about
20%,
by weight, PKHH; about 1 %, by weight, CYMEL 370 resin solution; about 59%, by
weight, methyl ethyl ketone; and about 20%, by weight, toluene.
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WO 01/03950 PCT/US00/17703
Ink design layer 25 of transfer portion 21, which layer may actually comprise
either a single ink layer or a plurality of ink layers, may be made using one
or more
conventional inks, such as polyester inks, polyester/vinyl inks, polyamide
inks andlor
acrylic inks, as well as the phenoxy ink described in commonly-assigned U.S.
Patent No.
6,099,944. Such inks typically comprise a resin of the type described above, a
suitable
pigment or dye, and one or more suitable volatile solvents. Ink design layer
25 is formed
in the conventional manner by depositing, preferably by gravure printing, one
or more
ink compositions of the type described above onto one or more desired areas of
lacquer
layer 23 and, thereafter, allowing the volatile solvents) of the ink
compositions) to
evaporate, leaving only the non-volatile ink components to form layer 25.
An example of polyester ink suitable for use in forming layer 25 comprises 18
wt % ViTEL~2700 (a copolyester resin commercially available from Bostik,
Middleton,
MA, having a high tensile strength (6700 psi) and a low elongation (3%
elongation)),
6 wt % pigment, 30.4 wt % n-propyl acetate and 45.6 wt % toluene. An example
of
another suitable polyester ink comprises ViTEL~ 2300 polyester resin (a
copolyester
resin also commercially available from Bostik having a high tensile strength
(8000 psi)
and a low elongation (7% elongation)).
Adhesive layer 21 preferably comprises a heat-activatable, polyester-based
adhesive; however, other types of heat-activatable adhesives, such as water-
based
acrylic adhesives (see, for example, U.S.S.N. 09/093,153, which application is
incorporated herein by reference), phenoxy adhesives (see, for example, U.S.
Patent No.
6,083,620) and the like, are also suitable for use as layer 27. (In fact,
certain pressure-
sensitive adhesives may also be used, instead of heat-activatable adhesives,
in forming
adhesive layer 27.) Adhesive layer 27 is preferably formed by depositing, by
gravure
printing or the like, onto (i) ink layer 25, (ii) exposed portions of lacquer
layer 23 and (iii) a
surrounding area of release coating 17 an adhesive composition comprising an
adhesive
resin and one or more volatile solvents and then evaporating the volatile
components) of
WO 01/039$0 CA 02378656 2002-0l-08 PCT/[J$00/17703
the composition (for example, by oven-heating for 30 seconds at 200
°F), leaving only
the non-volatile solid components) thereof to form layer 27.
An example of a suitable polyester-based adhesive composition for use in
forming a polyester-based adhesive of the type mentioned above comprises about
10.7 wt % of ViTEL~ 2700 polyester resin, about 10.7 wt% of ViTEL~ 2300, about
1.1
wt % of BENZOFLEX~ S404 glyceryl tribenzoate plasticizer (commercially
available
from Velsicol Chemical Corporation, Chicago, IL), about 1.1 wt % HULS 512
adhesion promoter (commercially available from Sivento Inc., Piscataway, NJ),
about
19.20 wt % toluene and about 57.10 wt % methyl ethyl ketone.
Adhesive layer 27 may additionally include an anti-blocking agent for use in
preventing adhesive layer 27 from adhering to the underside of carrier 15 when
a
label assembly comprising a plurality of transfer portions 21 on a single
support
portion13 is wound into a roll. The inclusion of said anti-blocking agent in
said
adhesive may be particularly desirable in those instances in which adhesive
layer 27
and carrier 15 have a high degree of adherence to one another, such as where
adhesive layer 27 comprises a polyester-based adhesive and carrier 15 is a
polyester
film. An example of a suitable anti-blocking agent is a wax, such as a
paraffinic wax,
which is added to the adhesive composition used to form adhesive layer 27 in
an
amount constituting about 1 wt % of said composition.
As seen in the examples below, in those instances in which a wax is included
in adhesive layer 27, a percentage of said wax is believed to migrate to other
layers
of label 11, including to the interface between release layer 17 and
protective lacquer
layer 23.
Moreover, as also seen in the examples below, said wax migration appears
to improve the release of protective lacquer layer 23 and adhesive layer 27
from
release layer 17. Nevertheless, notwithstanding the presence of said minute
quantities of wax at the surface of release layer 17, the present inventors
did not
detect any visually discernible amount of wax that was transferred from the
release
layer to the labeled article. Any such quantities of migrated wax do not
render a
release layer of the present invention outside the meaning of the term "non-
wax."
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WO 01/03950 CA 02378656 2002-O1-08 PCT/US00/17703
Label 11 may be used in the conventional manner by contacting adhesive
layer 27 with a desired article, such as a pre-heated (preferably to about 275-
300°F),
silane-treated clear glass container, while applying sufficient heat to the
bottom of
carrier 15 (e.g., using a platen heated to about 300-350°F) so as to
cause transfer
portion 21 to be released from support portion 13 and so as to cause adhesive
layer
27 to become heat-activated for bonding to the desired article. Prior to label
transfer,
the label construction is preferably pre-heated sufficiently so that the
adhesive layer
is heated to about 170-250°F.
The present inventors have noted that, when label 11 is used to decorate
silane-treated, clear glass containers, a good degree of label adherence and
scuff
resistance is achieved (i.e., at least about 5H pencil hardness, as measured
byASTM
standard D3363-92a for film hardness on a substrate).
One of the advantages associated with the use of a release layer like release
layer 17 is that transfer portion 21 of label 11 can be of the "wrap-around"
variety that
completely encircles a container.
The present invention may more clearly be understood by reference to the
following examples, it being understood that such examples are illustrative
and not
to be considered as limiting of the invention.
EXAMPLE 1
Four heat-activatable adhesive or protective lacquer films were coated onto
each of two types of coated polyethylene terephthalate (PET) film samples
(DuPont
92AXT coated polyester film), said two types of coated PET film samples being
similar to DuPont 140AXM 701 coated polyester film (and differing most notably
from
DuPont 140AXM 701 coated polyester film in that the two coated PET film
samples
comprised 92 gauge PET film, instead of 140 gauge PET film). The first of said
adhesive or protective films applied to said two coated PET film samples was a
polyester adhesive obtained by (i) depositing onto the coated PET film an
adhesive
composition comprising about 10.7 wt % of ViTEL~ 2700 polyester resin, about
10.7
wt% of ViTEL~ 2300, about 1.1 wt % of BENZOFLEX~ S404 glyceryl tribenzoate
plasticizer, about 1.1 wt % HULS 512 adhesion promoter, about 19.20 wt %
toluene
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CA 02378656 2004-O1-22
WO 01/0395D PCTNS00/17703
and about 57.10 wt % methyl ethyl ketone and (ii) drying the resulting product
at
70°C for 5 minutes to evaporate the volatile components thereof. The
second of said
films was an acrylic adhesive (see U.S.S.N. 09/093,153, which is incorporated
herein
by reference) obtained by (i) depositing onto the coated PET film an adhesive
composition comprising about 75 wt % of RHOPLEX~ GL-618 emulsion, about 17.5
wt % isopropyl alcohol, about 7.5 wt % of a 4% solution of NH40H, and about 1
wt
of Triton GR-5M dioctyl sodium sulfosuccinate surfactant and (ii) drying the
resulting product at 70°C for 5 minutes to evaporate the volatile
components thereof.
The third of said films was a water-based phenoxy adhesive (see U.S. Patent
No.
6,083,620) obtained by (i) depositing onto the coated PET film an adhesive
composition
comprising about 34 wt % PAHEN~ PKHW-34 phenoxy dispersion, about 12 wt % of
co-
solvent (2-4% butanol, 5-7% propylene glocyol n-propyl ether and 1-3% dimethyl
ethyl
amine), and about 54 wt % water and (ii) drying the resulting product at
70°C for 5 minutes
to evaporate the volatile components thereof. The fourth of said films was a
solvent-based
phenoxy protective lacquer obtained by (i) depositing onto the coated PET film
an adhesive
composition comprising about 25 wt % PKHH, about 46.6 wt % methyl ethyl
ketone, about
23.4 wt % toluene and about 5 wt % Dowanol PM propylene glycol methylether and
(ii)
drying the resulting product at 70°C for 5 minutes to evaporate the
volatile components
thereof.
The four films were removed from each of the two types of coated PET
samples, and the film surfaces from each coated PET sample that contacted the
sample were analyzed by XPS to determine whether there was any release
material
contamination from the samples on the film surfaces. Areas from the two types
of
coated PET samples which were not coated by film were also analyzed by XPS as
control samples. The results are shown below in TABLE 1.
TABLE I
Atomic
Sample C O Na N S
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WO 01/03950 CA 02378656 2002-0l-08 PCT/US00/17703
Uncoated 97.6 2.4 - - -
Sample
1
Phenoxy 85.4 14.6 - - -
Protective
Lacquer
from
Sample
1
Phenoxy 83.5 16.5 - - -
Adhesive
from
Sample
1
Polyester 80.4 19.6 - - -
Adhesive
from
Sample
1
Acrylic 71.2 22.9 0.5 4.2 1.2
Adhesive
from
Sample
1
Uncoated 96.3 3.7 - - -
Sample
2
Phenoxy 82.7 17.2 - - -
Adhesive
from
Sample
2
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WO 01/03950 CA 02378656 2002-O1-08 PCT/US00/1T703
Polyester 79.8 20.2 - - -
Adhesive
from
Sample 2
Acrylic 69.7 23.6 0.8 4.6 1.3
Adhesive
from
Sample 2
XPS measurements of the coated surfaces of the two types of coated PET
samples showed 97.6% carbon/2.4% oxygen and 96.3% carbon/3.7% oxygen,
respectively. This is consistent with a predominantly hydrocarbon surface. The
surface compositions of the four films deposited onto the two types of coated
PET
samples showed no significant change after having been peeled from the two
types
of coated PET samples. This indicates that the adhesive/protection layers were
free
of contamination from the support.
EXAMPLE 2
The four types of heat-activatable adhesive or protective lacquer films
described in Example 1 were formed on each of the two types of coated PET
support
samples of Example 1, and the respective release values for each were measured
with a TLMI Release Tester (see FINAT Test Method No. 3 of the FINAT Technical
Handbook, 4t" Edition) at a peel angle of 15 degrees using 810 tape at a peel
rate of
12 in/min at room temperature. The results are shown below in TABLE II and are
depicted graphically in Fig. 2.
TABLE II
Sample Release Value (g/in)Average (g/in)
Phenoxy protective 297, 335, 295, 268, 290
296,
lacquer 293, 296,243
on Sample 2
W~ 01/03950 CA 02378656 2002-O1-08 PCT/US00/17703
Phenoxy adhesive 215, 181, 212, 192, 198
on 188,
Sample 2 201, 191, 211, 195
Polyester adhesive 162, 162, 174, 173, 173
on 158,
Sample 2 197, 188
Acrylic adhesive 117, 116, 119, 99, 116
on 130
Sample 2
Phenoxy protective 224, 221, 218, 229, 224
243,
lacquer 223, 219, 218
on Sample1
Phenoxy adhesive 169, 149, 144, 158, 159
on 154,
Sample 1 159, 172, 172
Polyester adhesive 166, 123, 118, 144, 144
on 142,
Sample 1 164, 154
Acrylic adhesive 120, 93, 99, 103, 103
on 104, 99
Sample 1
The average release values for Sample 2 were higher than that for Sample 1.
It is believed that this higher release force is attributable to the higher
oxygen content
in Sample 2 than in Sample 1 (3.7% vs. 2.4% as detected by XPS).
EXAMPLE 3
The phenoxy protective lacquer, phenoxy adhesive and polyester adhesive
films described in Example 1 were formed on each of the two types of support
samples of Example 1, and the respective release values for each were
measured,
as in Example 2, with a 15 degree tester with 810 tape at 12 in/min (i) at
room
temperature (R.T.) and (ii) at room temperature after heating at 110°C
for 20 minutes
(110°C). The results are shown below in TABLE III and are depicted
graphically in
Fig. 3.
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WO 01/03950 cA 02378656 2002-0l-08 pCT/[JS00/17703
TABLE III
RELEASE
VALUES
(g/in)
Sample 2 Sample 2 Sample 1 at Sample 1
at at at
R.T. 110C R.T. 110C
Phenoxy 290 876 224 784
Protective
Lacquer
Phenoxy 198 272 159 277
Adhesive
Polyester 188 504 144 448
Adhesive
The above data indicates that the phenoxy protective lacquer experienced the
biggest heat-related release increase among the three films while the phenoxy
adhesive experienced the smallest release increase. The 20-minute heating was
used to simulate severe aging conditions for a label. In reality, a label
experiences
heat at 110°C for less than a second.
EXAMPLE 4
A plurality of samples of a first type of label construction were prepared,
said
first type of label construction comprising a Sample 1-type support, a phenoxy
protective lacquer layer of the type described above printed on top of said
support,
an ink layer printed on top of said protective lacquer layer, and a polyester
adhesive
of the type described above comprising a paraffinic wax printed on top of said
support, said protective lacquer layer and said ink layer. In addition, a
plurality of
samples of a second type of label construction were prepared, said second type
of
label construction differing from said first type of label construction in
that said second
label construction did not include an adhesive layer. Six samples of each type
of
label construction were tested one week after printing using the above-
described 15
27
CA 02378656 2002-O1-08
WO 01/03950 PCT/US00/17703
degree release test at room temperature. These samples were identified as
"Room
Temp." Another six samples of each were tested after heating at 110°C
for 20
minutes. These samples were identified as "11 OC/20 min." Additional batches
of six
samples of each label construction were heated in a 70 °C oven for 1, 2
and 4 weeks,
respectively, with adhesive side up to prevent blocking and then tested. These
samples were identified as "70C/1 week," "70C/2 week," and "70C/4 week." Still
another six samples of each label construction were stored at room temperature
for
six weeks and then tested. These samples were identified as "RT 6." The
release
values obtained (g/inch) from the above-described testing are set forth below
in
TABLE IV and are shown graphically in Fig. 4.
TABLE IV
Constru- Room 110C/20 70C/1 70C/2 70C/4 RT/6
ction Temp. min week week week
First 78 191 244 255 374 119
type
Second 183 733 519 626 631 249
type
As can be seen, the heat-aged condition increased the release value for both
types of label constructions.
EXAMPLE 5
XPS measurements were obtained for the adhesive layer, the protective
lacquer layer and the release coating of the support portion of the first type
of label
construction described in Example 4. The oxygen % values from these
measurements are set forth below in TABLE V and are depicted graphically in
Fig.
5. (Virgin film denotes the surface of the adhesive or protective lacquer
material cast
on a substrate or the virgin release coating without any material
contamination.)
TABLE V
Virgin Room 110C/2 70C/1 70C/2 70C/4 RT/6
film Temp 0 min week week week
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WO 01/03950 CA 02378656 2002-O1-08 PCT/US00/17703
Ad hes- 22.4 16.0 13.6 15.3 16.7 18.0 18.1
ive
Protect-17.5 10.0 6.8 5.0 6.1 6.2 11.6
ive
Relea- 3.6 2.4 1.8 2.2 2.1 2.6 2.6
se
As can be seen from the above data, the wax from the adhesive layer migrated
to the protective lacquer and release layers.
EXAMPLE 6
A plurality of samples of a third type of label construction were prepared,
said
third type of label construction differing from said first type of label
construction in that
the support used was similar, but not identical, to the support used in the
first type
of label construction and in that the adhesive used was the polyester adhesive
of
Example 1 (which does not include a paraffinicwax orthe like). In addition, a
plurality
of samples of a fourth type of label construction were prepared, said fourth
type of
label construction differing from said third type of label construction in
that said fourth
label construction included the acrylic adhesive layer of Example 1. Several
samples
of each type of label construction were tested one week after printing using
the
above-described 15 degree release test at room temperature. These samples were
identified as "Room Temp." Another group of samples of each type of label
construction were tested after heating at 110 °C for 20 minutes. These
samples were
identified as "110C/20 min." Another group of several samples of each label
construction were heated in a 70°C oven for 1 week with adhesive side
up to prevent
blocking and then tested. These samples were identified as "70C/1 week." The
results of the above-described testing are shown graphically in Fig. 6.
EXAMPLE 7
XPS measurements were obtained for the adhesive layer, the protective
lacquer layer and the release coating of the support portion of the third type
of label
construction described in Example 6. The oxygen % values from these
29
WO 01/03950 CA 02378656 2002-O1-08 pCT~S00/17703
measurements are depicted graphically in Fig. 7. (Virgin film denotes the
surface of
the adhesive or protective lacquer material cast on a substrate or the virgin
release
coating without any material contamination.)
The embodiments of the present invention recited herein are intended to be
merely exemplary and those skilled in the art will be able to make numerous
variations and modifications to it without departing from the spirit of the
present
invention. For example, it should be appreciated that one may add, either
directly or
through trans-layer migration, trace or non-functional minor amounts of waxes
or
silicones to the release layer described herein as "non-wax" and "non-
silicone"
without being outside the scope of applicants' invention. Thus, the terms "non-
wax"
and "non-silicone" as used herein is intended to embrace this possibility. All
such
variations and modifications are intended to be within the scope of the
present
invention as defined by the claims appended hereto.
