U.S. patent application number 10/359347 was filed with the patent office on 2003-10-30 for packaging material and products comprising indicia-former which changes from a first visual condition to a second visual condition and indicates a characteristic of the package contents.
Invention is credited to Aloisi, Robert J., Hollenberg, David H., Schmelzer, Michael A..
Application Number | 20030200725 10/359347 |
Document ID | / |
Family ID | 29255240 |
Filed Date | 2003-10-30 |
United States Patent
Application |
20030200725 |
Kind Code |
A1 |
Aloisi, Robert J. ; et
al. |
October 30, 2003 |
Packaging material and products comprising indicia-former which
changes from a first visual condition to a second visual condition
and indicates a characteristic of the package contents
Abstract
Packaging materials, in particular, film and products that are
marked with an energy sensitive indicia-former. The film has at
least one heat sensitive indicia-former on at least part of the
film. The film comprises a thin film substrate which is
substantially transparent to radiant energy. Associated with at
least part of the film substrate is an absorbent material which is
sufficiently opaque to radiant energy to absorb said radiant energy
and convert the radiant energy into heat energy. The indicia-former
undergoes conversion from a first visual condition to a second
visual condition upon exposure to heat energy from the absorbent
material. The film is used preferably as a shrink wrap of the open
top of drink containers and to identify the contents of the
container.
Inventors: |
Aloisi, Robert J.;
(Kaukauna, WI) ; Hollenberg, David H.; (Kaukauna,
WI) ; Schmelzer, Michael A.; (Appleton, WI) |
Correspondence
Address: |
John S. Child, Jr., Esquire
DANN, DORFMAN, HERRELL AND SKILLMAN
Suite 720
1601 Market Street
Philadelphia
PA
19103-2307
US
|
Family ID: |
29255240 |
Appl. No.: |
10/359347 |
Filed: |
February 5, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10359347 |
Feb 5, 2003 |
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10183415 |
Jun 28, 2002 |
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60302232 |
Jun 29, 2001 |
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60387366 |
Jun 10, 2002 |
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Current U.S.
Class: |
53/442 |
Current CPC
Class: |
B65D 77/2012 20130101;
B65B 7/2885 20130101; B65B 61/06 20130101; B65B 61/26 20130101;
B65H 2701/1752 20130101; B65B 7/167 20130101; B26F 1/3846 20130101;
B65H 23/048 20130101; B65B 53/02 20130101; B26D 1/045 20130101;
B65H 23/14 20130101; B65H 23/16 20130101 |
Class at
Publication: |
53/442 |
International
Class: |
B65B 053/02 |
Claims
We claim:
1. A packaging material which comprises: a) a substrate; and b) at
least one indicia-former carried by said substrate which undergoes
conversion from a first visual condition to a second visual
condition upon exposure to heat energy.
2. The packaging material according to claim 1, wherein the
material is flexible.
3. The packaging material according to claim 1, wherein the
material is dimensionally stable.
4. The film according to claim 1, wherein the absorbent material
comprises at least one radiant energy absorbing component selected
from the group consisting of carbon black, graphite and iron
oxide.
5. The flexible material according to claim 1, wherein the
indicia-former undergoes a change in perceptibility.
6. The flexible material according to claim 1, wherein the
indicia-former undergoes a change in appearance.
7. The flexible material according to claim 1, wherein the
indicia-former undergoes a change in hue.
8. The flexible material according to claim 1, wherein the
indicia-former undergoes a change in shade.
9. The flexible material according to claim 1, wherein the
indicia-former undergoes a change in brightness.
10. The flexible material according to claim 1, wherein the
indicia-former undergoes a change in lightness.
11. The flexible material according to claim 1, wherein the
indicia-former undergoes a change in saturation.
12. The flexible material according to claim 1, wherein the
indicia-former undergoes a change in color.
13. The flexible material according to claim 1, wherein the
indicia-former undergoes a change in reflectiveness.
14. The flexible material according to claim 1, wherein the
indicia-former undergoes a change in absorbtivity.
15. The flexible material according to claim 1, wherein the
indicia-former undergoes a change from white to black.
16. The flexible material according to claim 1, wherein the
indicia-former undergoes a change from light gray to dark gray.
17. The film according to claim 1, wherein the indicia-former is
configured to comprise a circle enclosing the letter "x."
18. The film according to claim 1, wherein the indicia-former is
configured to comprise a check mark.
19. The film according to claim 1, wherein the indicia-former is
configured to comprise words identifying beverage options.
20. The film according to claim 1, wherein the heat sensitive
indicia-former comprises thermochromic ink.
21. The film according to claim 20, wherein the thermochromic ink
undergoes conversion from white to black upon exposure to heat
energy from the absorbent material.
22. The film according to claim 20, wherein the thermochromic ink
is applied onto the film substrate by printing.
23. The film according to claim 22, wherein the thermochromic ink
is applied onto the film substrate by flexographic printing.
24. A product which comprises: a) a substrate; and b) at least one
indicia-former carried by said substrate which undergoes conversion
from a first visual condition to a second visual condition upon
exposure to heat energy.
25. A flexible material which comprises: a) a thin film substrate
which is substantially transparent to radiant energy; b) an
absorbent material associated with at least a portion of the
substrate, said absorbent material being sufficiently opaque to
radiant energy to absorb said radiant energy and convert said
energy into heat energy; and c) at least one indicia-former carried
by said film substrate which undergoes conversion from a first
visual condition to a second visual condition upon exposure to heat
energy from said absorbent material.
26. A heat-shrinkable flexible packaging film, said film having at
least one energy sensitive indicia-former on the surface thereof,
said film comprising: a) a thin film substrate which is flexible
and shrinks when heated, and which is substantially transparent to
radiant energy, thereby remaining substantially unchanged on
exposure to radiant energy; b) an absorbent material associated
with at least a portion of said substrate, said absorbent material
being sufficiently opaque to radiant energy to absorb said energy
and convert said radiant energy into heat energy, with said heat
energy being transferred to said indicia-former; and c) said energy
sensitive indicia-former carried by said film being caused to
undergo conversion from a first visual condition to a second visual
condition upon exposure to said heat energy.
27. The packaging film according to claim 26, wherein the
temperature at which the energy sensitive indicia-former undergoes
conversion from one visual condition to another is lower than the
temperature at which said film is caused to shrink.
28. The packaging film according to claim 26, wherein the film
substrate is selected from the group consisting of polyvinyl
chloride, polyolefins such as polypropylene, linear-low density
polyethylene, low density polyethylene, high density polyethylene,
copolymers of ethylene and vinyl acetate, copolymers of ethylene
and vinyl alcohols, isonomers; copolymers of vinylidone chloride,
copolymers of ethylene and acrylic acid, polyamides, polyesters,
polystyrene, nylon and copolymers of ethylene and octenes.
29. The packaging film according to claim 28, wherein the film
substrate is a polyvinyl chloride or a polyolefin.
30. The packaging film according to claim 29, wherein the film
substrate is a bi-axially oriented shrink film having a thickness
of between about 0.0127 millimeters and about 0.0381
millimeters.
31. The packaging film according to claim 26, wherein the absorbent
material comprises at least one radiant energy absorbing component
selected from the group consisting of carbon black, graphite and
iron oxide.
32. The flexible material according to claim 26, wherein the
indicia-former undergoes a change in perceptibility.
33. The flexible material according to claim 32, wherein the
indicia-former undergoes an enhancement in perceptibility.
34. The packaging film according to claim 26, wherein the heat
sensitive indicia-former comprises an ink elected from the group of
thermochromic pigment, thermochromic dye and thermochromic ink.
35. The packaging film according to claim 34, wherein the heat
sensitive indicia-former comprises thermochromic ink.
36. The packaging film according to claim 35, wherein the
thermochromic ink undergoes conversion from white to black upon an
increase in temperature due to heat energy from the absorbent
material.
37. The packaging film according to claim 26, wherein the heat
sensitive indicia-former is applied to the film substrate by
printing.
38. The packaging film according to claim 37, wherein the
thermochromic ink is applied onto the film substrate by
flexographic printing.
39. The packaging film of claim 26, wherein the thermochromic ink
is applied to the film surface by brushing.
40. The film according to claim 26, wherein the indicia-former is
configured to comprise a circle enclosing the letter "x."
41. The film according to claim 26, wherein the indicia-former is
configured to comprise a check mark.
42. The film according to claim 26, wherein the indicia-former is
configured to comprise words identifying beverage options.
43. A method of sealing a beverage in an open-top container, said
method comprising the steps of a) filling the container with the
beverage; b) applying over the open top of the container the
heat-shrinkable flexible packaging film of claim 26; and c)
exposing the film to at least one radiant energy source, resulting
in the conversion of the radiant energy to heat energy that causes
the film to shrink and seal the open top of the container and
change the indicia-former from a first visual condition to a second
visual condition.
44. The method according to claim 43, wherein the radiant energy
sources used to shrink and seal the film and to change the
indicia-former from the first visual condition to the second visual
condition are distinct.
45. The method according to claim 43, wherein the radiant energy
source is a halogen lamp.
46. The method according to claim 43, wherein the radiant energy
source is a tungsten halogen lamp emitting light energy having wave
lengths of between about 600 nm and about 1400 nm.
47. In combination, an open-top container, the open top of which is
covered by a heat-shrinkable flexible packaging film, said film
comprising: a) a thin film substrate which is flexible and shrinks
when heated, and which is substantially transparent to radiant
energy, thereby remaining substantially unchanged by radiant
energy; b) an absorbent material associated with at least a portion
of said substrate, said absorbent material being sufficiently
opaque to radiant energy to absorb said radiant energy and convert
said radiant energy into heat energy; and c) an energy sensitive
indicia-former carried by said film and comprising an ink
formulation which undergoes conversion from a first visual
condition to a second visual condition upon exposure to heat energy
converted from the absorbent material.
48. The combination of claim 47, wherein the indicia-former
undergoes conversion at a temperature below that at which said film
is caused to shrink.
49. The combination of claim 47, wherein the absorbent material
comprises at least one radiant energy absorbing component selected
from the group consisting of carbon black, graphite and iron
oxide.
50. The combination of claim 47, wherein the heat sensitive
indicia-former is selected from the group consisting of
thermochromic pigment, thermochromic dye and thermochromic ink.
51. The combination of claim 47, wherein the heat sensitive
indicia-former is thermochromic ink.
52. The combination of claim 47, wherein the open-top container is
a beverage container.
53. The combination according to claim 47, wherein the
indicia-former is configured to comprise a circle enclosing the
letter "x."
54. The combination according to claim 47, wherein the
indicia-former is configured to comprise a check mark.
55. The combination according to claim 47, wherein the
indicia-former is configured to comprise words identifying beverage
options.
56. A method of manufacturing a flexible film packaging material,
said method comprising the steps of: a) applying to a thin film
substrate an absorbent material being sufficiently opaque to
radiant energy to absorb said radiant energy and convert said
radiant energy into heat energy; and b) applying to the substrate
of the film a heat sensitive indicia-former which undergoes
conversion from a first visual condition to a second visual
condition upon exposure to heat energy.
57. The method according to claim 56, wherein application steps (a)
and (b) are carried out by printing the absorbent material and heat
sensitive indicia-former onto the film.
58. A heat shrinkable flexible packaging film, said film having at
least one energy sensitive indicia-former on the surface thereof,
said film comprising: a) a thin film substrate which is flexible
and shrinks when heated, and which is substantially transparent to
energy, thereby remaining substantially unchanged on exposure to
energy; and b) said energy sensitive indicia-former carried by said
film comprising an ink formulation which undergoes conversion from
a first visual condition to a second visual condition upon exposure
to energy.
59. The heat shrinkable flexible packaging film according to claim
58, wherein the indicia-former is selected from the group
consisting of photochromic ink and electrochromic ink.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/387,366, filed Jun. 10, 2002, and U.S. patent
application Ser. No. 10/183,415, filed Jun. 28, 2002, both of which
are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] This invention pertains generally to packaging material and
products which comprise (a) a substrate; and (b) an energy
sensitive indicia-former carried by the substrate. The invention
also pertains, in particular, to the use of such indicia-former on
containers, having the capability of indicating the contents of
such containers.
BACKGROUND OF THE INVENTION
[0003] In numerous instances, products are made and packaged that
do not have markings that would be useful, for example, to identify
the product, parts of the product or how to use the product. This
is also true for packaging. Product identifiers on packaging
material such as labels require time to complete and affix to the
package, particularly if used in fast food preparation.
[0004] In fast food outlets, convenience stores and the like,
beverage dispensing machines are used which are capable of
dispensing a number of beverages of different brands and flavors.
These beverages are usually poured into disposable paper cups
having advertising printed thereon, but bearing no markings to
identify the cups' contents.
[0005] When a beverage order includes a number of different brands
and/or flavors, it is extremely difficult to determine the contents
of each cup by visual inspection. Identification is further
complicated by the placement of thermoformed lids over the cups to
prevent spillage.
[0006] As a consequence of this problem, mixups occur and customers
get the wrong beverage and do not discover the error until they
taste it.
[0007] One way in which this confusion can be avoided is by using
paper cups of different colors or having different designs or
markings thereon. However, this requires a large inventory of cups,
and the person filling the order must be attentive to selecting the
appropriate cup in order to avoid the error of filling the selected
cup with the incorrect beverage.
[0008] Other ways of solving this problem include the use of labels
affixed to the outer surface of the container or thermoformed lids
having manually deformable buttons identifying drinks of various
kinds. A further approach is marking the identity of the drink onto
the container or its lidding with a pen, i.e., by circling the
drink type or checking or box a dot next to a specific drink type.
These solutions require an inventory of container labels or lids
and consistently attentive servers.
SUMMARY OF THE INVENTION
[0009] Accordingly, it is an object of the invention to provide a
product comprising a substrate and an energy sensitive
indicia-former carried by said substrate that undergoes conversion
from a first visual condition to a second visual condition.
[0010] It is another object of this invention to provide a
packaging material which comprises such energy sensitive
indicia-former. It is a further object of this invention to provide
a packaging material which shrinks in a controlled fashion upon
exposure to heat of appropriate intensity, i.e. a shrink wrap
material, thereby serving as a replacement for plastic lids as
closures for drink containers.
[0011] It is a further object of this invention to provide a
closure which comprises as the heat sensitive indicia-former,
thermochromic ink that is converted from a first visual condition,
preferably a visually indistinct, low contrast condition, to a
second visual condition, preferably a visually distinctive, high
contrast condition, when undergoing a temperature change. The first
visual condition is preferably white. The second visual condition
is preferably black or another dark hue, so that the conversion
from the first to the second condition is clearly visually
perceptible, thereby enabling the use of the ink as a marker of the
contents of the container to which the closure is applied.
[0012] These and other objects are achieved by the packaging
material and products of the present invention which comprise (a) a
substrate and (b) an energy sensitive indicia-former carried by the
substrate, which undergoes conversion from a first visual condition
to a second visual condition upon exposure to heat energy. A
preferred embodiment of the invention is a flexible packaging
material which comprises (a) a substrate that is substantially
transparent to radiant energy, (b) an energy absorbent material
associated with at least a portion of the substrate, the absorbent
material being sufficiently opaque to radiant energy to absorb and
convert radiant energy into heat energy, thereby raising the
temperature of the absorbent material, and (c) an energy sensitive
indicia-former carried by said substrate which undergoes conversion
from a first visual condition to a second visual condition upon an
increase in temperature resulting from exposure to heat energy from
the absorbent material. In a preferred form, the packaging material
is a flexible film used to cover open-top containers. Other aspects
of the invention include a method of manufacturing the
above-described packaging and open-top containers covered by the
above-described closures, and a method of filling an open-top
container with a beverage and sealing the container with such
closures.
BRIEF DESCRIPTION OF THE DRAWING
[0013] FIG. 1 illustrates a configuration used for the
indicia-former.
DETAILED DESCRIPTION OF THE INVENTION
[0014] The invention has many applications. These include use of
the indicia-former in packaging, product marking, decorative and
labeling material and as a barrier material to protect articles
from damage from, for example, water, heat, cold and radiation. The
products to be marked can be any product to which the
indicia-former can be affixed. The packaging may be any material
continuously used for packaging, such as paper, dimensionally
stable materials such as cardboard and heat sensitive packaging
such as polyurethane or transparent clam shells used to hold
take-out food. The packaging material may also be a film, and
preferably a flexible film.
[0015] The present invention will be described below with
references to thin film closures which are preferably transparent.
A particularly preferred type of film is shrink film, commonly
referred to as "shrink wrap film." It should be understood,
however, that the packaging material of the invention may also be
embodied in a variety of other forms, such as thermoformed lids,
packaging for construction materials, paper goods and
pharmaceutical containers.
[0016] End uses of these films include food packaging (for example,
oxygen and moisture barrier bag for frozen poultry; prime meat cuts
and processed meat and cheese products for preservation of
freshness and hygienics) and non-food packaging (for example,
"overwraps" for protecting goods against damage, soiling, tampering
and pilferage) during transporting, distribution, handling and
display. A typical end use is in retail sales where the films are
wrapped air-tight around single or multiple items of compact disks,
audio/video tapes, computer software boxes, magazines,
confectionery, boxed products, single serve bowls, etc. Another
common end use is in wholesale marketing, where multiple containers
of bottled and canned goods such as beverages, condiments and
personal hygiene products are sold in bulk. Yet another example is
in courier shipping, where singular items of shrink-wrapped
sporting goods and household appliances are safely transported
without the need for bulky protective cardboard cartons.
[0017] The term "shrink film" refers to a plastic wrapping film
which has the capability of shrinking when it is heated to near the
melting point of the film. These films are commonly manufactured
from plastic resins such as polyvinyl chloride (PVC); polypropylene
(PP); linear-low density polyethylene (LLDPE); low density
polyethylene (LDPE); high density polyethylene (HDPE); copolymers
of ethylene and vinyl acetate (EVA); copolymers of ethylene and
vinyl alcohols (EVOH); ionomers (e.g., SURLYN.RTM., a registered
trademark of E. I. duPont de Nemours and Co., Wilmington, Del.);
copolymers of vinylidene chloride (e.g., PVDC, SARAN, a trademark
of the Dow Chemical Company); copolymers of ethylene and acrylic
acid (EAA); polyamides (PA); polyester, polystyrene, nylon and
copolymers of ethylene and octene.
[0018] Film Substrate
[0019] Films particularly suitable for this purpose are flexible
and substantially transparent to radiant energy. It will be
appreciated by those skilled in the art that the thickness of the
film can be varied without adversely affecting the operation of the
present invention. For certain applications, when greater strength
is required, substantial film thickness may be appropriate, such as
200-gauge (0.05 mm) and more. Considerations such as price, tear
resistance, degree of shrink and clarity will affect the selection
of an appropriate film and thickness to suit the commercial
objective to be met. When used in contact with food or beverage
products, the film should be approved by the appropriate regulatory
authorities.
[0020] If the film is a shrink wrap film, the preferred shrink film
substrate will have shrink characteristics suitable for the given
packaging objectives. Some of these characteristics include the
degree and orientation of the shrink and whether the shrink is to
occur in both or only in one direction. Most common commercially
available shrink film substrates are substantially transparent,
meaning that light, infrared radiation and other forms of radiant
energy pass through the substrate with very little, if any,
absorption. In this case, substantially transparent means that at
least 75% and preferably more than 90% of radiant energy passes
through said film. Such transparency has led to the utilization of
a heat absorbing medium, in physical contact with the film, to
provide sufficient heat transfer to cause the desired shrink. A
preferred film is a bi-axially oriented thin shrink film, having a
preferred thickness of between approximately 50 to 150-gauge
(0.0127 mm to 0.0381 mm) with the most preferred range being from
60 to 75-gauge (0.0152 mm to 0.0191 mm). Films meeting these
specifications are a 75-gauge (0.0191 millimeter). CLYSAR.RTM.
polyolefin shrink film sold by Bernis Corporation of Minneapolis,
Minn. and a 75-gauge 0.0191 millimeter Exfilm.TM. polyolefin shrink
film sold by Intertape Corp. of Bradenton, Fla.
[0021] An alternate film is a shrink film that is made of polyvinyl
chloride and sold under the trade name #2024 REYNOLON.RTM., a trade
name of Reynolds Metals Company of Richmond, Va. Such films are
disclosed in U.S. Pat. No. 6,291,037 B1 to Bakker, the contents of
which are incorporated by reference herein.
[0022] Energy Absorbent Material
[0023] The energy absorbent material used in practicing this
invention is a material which is adapted to be associated with at
least a portion of the film substrate and is sufficiently opaque to
absorb energy, preferably radiant energy. Radiant energy includes
electromagnetic energy. See The Condensed Chemical Dictionary,
8.sup.th Edition, Revised by Hawley, Gessner G. (Van Nostrand
Reinhold Company, New York, 1971) p. 750, in which radiation is
defined as "energy in the form of electromagnetic waves (also
called radiant energy or light)." The energy absorbent material
functions to convert radiant (electromagnetic) energy into heat
energy, thereby causing an increase in temperature of the film.
[0024] The absorbent material may be formed on the film by a
variety of well-known methods such as printing means (flexographic,
rotogravure, screen, transfer, etc.), brushing, spray coating,
electrostatic coating, electrodeposition coating, flow coating,
roller coating, dip coating, and the like. Printing is the
preferred method (e.g., using flexographic or rotogravure
techniques). The energy absorbent material includes at least one
radiant energy absorbing component such as carbon black, graphite,
iron oxide or the like. It will be appreciated by those skilled in
the art that while certain specific energy absorbing materials have
been identified, other material will also be suitable. What is
desired is that the energy absorption rate of the material be
sufficient so that upon exposure of the material to radiant energy,
the heat generated will cause the desired degree of shrinkage of
the film substrate in a predetermined amount of time.
[0025] In some cases, such films may require special treatment to
be made more adaptable to printing of the energy absorbent material
thereon, such as the application of a charged electric field, known
as corona treating, which is done before printing to ensure
adhesion of the absorbent material, and its carrier vehicle, if
any. Other methods of promoting adhesion of the absorbent material
include flame treatment or chemical primer application. For other
films, such as polyvinyl chloride shrink films, corona treating is
not necessary for good printing results.
[0026] In an alternate embodiment, the absorbent material may be
physically incorporated into the film substrate and absorbs the
radiant energy from within the film. This latter approach is less
preferred to printing the absorbent material onto the film, since
incorporating the absorbent material into the film may change the
heat shrink characteristics of the film, such as flexibility,
degree of shrink and the like.
[0027] According to the present invention, radiant energy means
energy which may be transmitted from a suitable source to the
absorbent layer, where it is absorbed to produce heat. In a
preferred embodiment, the radiant energy is infrared radiation,
which is efficiently absorbed by the absorbent layer, but not the
film. In this way, heat energy is provided directly to the heat
shrinkable film, thus avoiding the necessity of using any other
heating medium, such as hot water or air, as in the past to carry
the heat to the film. Thus, radiant energy in this context means
any form of radiant energy that is transmissible through a medium
such as air, without being substantially absorbed thereby. In a
preferred embodiment, the radiant energy is supplied by a halogen
bulb.
[0028] Carbon black provides good results when incorporated as the
energy absorbent material on or in the film substrate. In
particular, carbon black responds readily to the radiant energy
output of a halogen bulb, which emits energy primarily in the
visible and near infrared spectrum. Carbon black is a standard
pigment in printing inks. This combined ability to blend with
existing printing inks, and to absorb radiant energy such as
infrared radiation, makes it well suited for use in the present
invention.
[0029] A preferred energy absorbing material is carbon
pigment-containing black ink sold by Coates Ink, a division of Sun
Chemical, under the trade name Brazilia TN15787. This ink is
readily adapted for printing onto the film substrate. The Brazilia
inks are available in many colors and are broadly usable as
absorbing materials according to the invention if the ink meets the
requirements specified hereinabove. In a preferred embodiment, a
reflective coating, preferably composed of white ink, is overlaid
on the energy absorbent material in an amount sufficient to provide
appropriate contrast with the areas the indicia-former, after it is
caused to change from the first visual condition to the second
visual condition, so that the latter is more easily observed. A
preferred white ink is also sold by Coates Ink under the trade
names Lunar TN12316 and Alfalam. The use of a white ink overlay
depends on whether a black or white background is more effective in
facilitating visual observation of the change in the indicia-former
from a preferred low contrast, first visual condition to the high
contrast, second visual condition.
[0030] Energy Sensitive Indicia-Former
[0031] As described hereabove, the energy sensitive indicia-former
changes from one visual condition to a second visual condition.
Change in visual condition would include but not be limited to
change in appearance, hue, shade, perceptibility, including an
enhancement in perceptibility, brightness, lightness,
reflectiveness, absorptivity and color, including, for example,
light gray to dark gray and white to black.
[0032] The preferred indicia-former is a thermochromic pigment or
dye, which may be dispersed in a suitable carrier. These
thermochromic materials are preferably used in the form of a
thermochromic ink incorporating a thermochromic pigment or dye in a
carrier vehicle. The thermochromic ink may be applied to the film
substrate by the methods identified above for applying the
absorbent material to the substrate. The preferred method is
printing the thermochromic ink onto the substrate. The energy
sensitive indicia-former is preferably an irreversible
thermochromic ink that undergoes a change from white to black when
adequately heated. A preferred thermochromic ink, (sold by Sherwood
Technologies Limited of Nottingham, UK under the trade name
Sherwood Type 90) is white below about 90.degree. C. and undergoes
an irreversible color change to black above about 90.degree. C.
Those of ordinary skill in the art will understand there are a
variety of ink systems comprising one or more inks that can
function as the radiant energy absorbent material and as the heat
sensitive indicia-former.
[0033] Those of ordinary skill in the art will understand that a
variety of ink colors can be used to obtain satisfactory results
with the present invention and that a variety of energy sensitive
indicia-formers other than thermochromic ink can also be used.
Other inks that can be used in the invention as indicia-former are
photochromic ink and electrochromic ink, such as those disclosed in
U.S. Pat. No. 5,830,529 to Ross, the entire disclosure of which is
incorporated herein by reference. Of course, photochromic and
electrochromic inks, when employed as the indicia-former, would not
require an absorbent layer. Instead, the indicia-former would be
exposed directly to energy capable of causing the desired visual
transformation of the indicia-former. In addition, those of
ordinary skill in the art will understand that it is not necessary
to coat the entire film substrate with ink. Moreover, those of
ordinary skill in the art will appreciate that ink patterns can be
used in applying the indicia-former to the substrate.
[0034] Preferred Applications of Absorbent and Indicia-Former
Layers
[0035] As noted above, in a particularly preferred embodiment
relating to films used to cover drink containers, an absorbent
material comprising an ink composition containing carbon black is
printed onto the film substrate. As this ink composition is black
in appearance due to its carbon black content, white ink, for
example, is applied over the portions of the black ink on which the
indicia-former is to be located to show the contents of the
container, in order to provide appropriate contrast for the
indicia-former. Then the indicia-former is superimposed on the
areas of white ink, preferably by printing.
[0036] There are, of course, numerous possible combinations of the
absorbent layer, optional contrast layer and energy sensitive
indicia-former that can be employed in carrying out the
invention.
[0037] Those of ordinary skill in the art will understand that a
variety of ink concentrations can achieve satisfactory results in
the present invention. The second ink which acts as an energy
sensitive indicia-former may be, as identified above, an ink that
undergoes conversion from one color to another that contrasts with
the color of the absorbent material upon a predetermined increase
in temperature. Alternatively, it may be an ink that undergoes a
different sort of visually observable conversion, such as a dye or
luminescent pigment that is covered by a patch that disintegrates
upon a specific increase in temperature. The requirements for the
energy sensitive indicia-former are that they undergo a conversion
from a first visual state to a second visual state upon exposure to
appropriate energy, and that such changes in visual state or
condition are perceptible to the human eye.
[0038] Radiant Energy Source
[0039] According to one embodiment of the invention, the radiant
energy source produces radiant energy by emitting light having wave
lengths in the visible and near infrared range. Those of ordinary
skill in the art will understand that the wave length of the energy
emitted by the radiant energy source is not particularly critical,
provided that the absorbent material chosen is sufficiently
absorbent within the range of the wave lengths emitted, so that
conversion of the radiant energy into heat energy and increased
temperature of the film is reasonably rapid.
[0040] A preferred radiant energy source is a conventional halogen
lamp emitting light energy having wave lengths between about 600 nm
to about 1400 nm. It has been found that tungsten halogen lamps are
a preferred radiant energy source. However, those of ordinary skill
in the art will understand that a number of different radiant
energy sources are available which produce sufficient visible and
near infrared radiation, such as xenon arc lamps. The energy source
is preferred to have a total wattage of between 50 and 150 watts,
and most preferably comprises one 100-watt bulb. The wattage should
be chosen to provide sufficient energy to shrink the film without
burning through the film. One radiant energy source that has been
successfully used is a Osram JC24V-100 WG6.35 from Osram Sylvania,
Inc., of Danvers, Mass.
[0041] In a preferred embodiment, the invention is used on
packaging film which shrinks to form at least part of the package
when exposed to heat. The packaging film includes a thin film
substrate that contracts or shrinks when heated and which is
substantially transparent to radiant energy. The film also includes
an absorbent material that is sufficiently opaque to radiant energy
to absorb and transfer to the substrate enough heat energy to cause
the substrate to shrink when the film is exposed to a source of
radiant energy. In a particularly preferred embodiment, the
packaging film performs the function of a beverage container
lid.
[0042] In use, radiant energy is caused to impinge on the film
covering the container. The film has several marking options, such
as "soda," "diet cola," and "water," imprinted on the film. Next to
each option is an indicia area having absorbent and thermochromic
ink layers.
[0043] In a particularly preferred form, the marking options
printed onto the film have absorbent, reflective or
contrast-enhancing and thermochromic layers. Accordingly, after the
container is filled with a specific beverage, radiant energy is
directed to the film at the beverage option selected. The radiant
energy may be directed by indexing a variable mask situated,
between the radiant energy source and the indicia-former. The
radiant energy source may comprise one lamp or more than one lamp.
The radiant energy mask may have one orifice or several orifices
through which the radiant energy is directed to the film. If the
radiant energy is directed to the film at the beverage option
selected through one orifice, the radiant energy results in the
heating of the absorbent material precisely at the beverage option
selected and thereby causes a localized increase in temperature of
the indicia-former identifying that option. The increase in
temperature causes the indicia-former identifying that option to
change color (e.g., from white to black). The resultant black
marking identifies the option selected, thus indicating the
contents of the container. As radiant energy is not directed at the
indicia-formers identifying other drink options, those
indicia-formers do not change color. Accordingly, the beverage
option selected is identified by the color change of the particular
indicia-former identifying that option.
[0044] For example, if the container is filled with diet cola, the
radiant energy is directed to, and causes the indicia-former
identifying "diet cola" to change color, preferably from white to
black. In this embodiment, the indicia-former changes to a color
that contrasts with the background, so that the mark formed is
easily identifiable. The identification marking can take numerous
configurations. Preferred configurations are a circle enclosing the
letter "x," a check mark, or even a word or words identifying the
beverage. An illustration of one of these configurations, namely
the circle enclosing the letter "x," is shown in FIG. 1.
Preferably, the source of the radiant energy is positioned about
0.5 inch away from the film. In a most preferred form, the film is
0.932 inch from the center of the bulb filament and 0.464 inch from
the top of the bulb. If the radiant energy source is one 100-watt
halogen bulb, the film is exposed to the activated source typically
for one-quarter second, with the power applied at 30% of
capacity.
[0045] Alternatively, radiant energy can be directed to the film
precisely at the beverage options not selected so that the beverage
option selected would be the only option identified that did not
undergo a change from one visual condition to a second visual
condition. This process can be accomplished by directing the
radiant energy through several orifices in the variable mask. The
orifices are aligned to ensure that the radiant energy is directed
to the film precisely at the indicia-former identifying the
beverage options not selected.
[0046] In a preferred embodiment, this marking of the
identification of the drink is carried out in the same sequence of
operations during which the container is filled and the shrink wrap
film cover is applied to the open top of the container; however,
the energy source used for the marking operation is distinct from
the energy source used to shrink wrap the cover over the open
container.
[0047] The invention also includes a method of manufacturing the
film of the invention. According to this method, an absorbent
material is applied onto at least a portion of a thin film
substrate which is substantially transparent to radiant energy. The
absorbent material is sufficiently opaque to radiant energy to
absorb radiant energy and convert it to heat energy. Then an energy
sensitive indicia-former which undergoes conversion from a first
visual condition to a second visual condition upon exposure to heat
energy is applied onto the film substrate. The preferred methods of
application are by printing.
[0048] The invention also is directed to drink containers covered
by heat shrinkable flexible films. According to this embodiment of
the invention, an open-top container is covered by a heat
shrinkable, flexible packaging film having at least one heat
sensitive indicia-former on the surface thereof. The film material
comprises a thin film substrate which is flexible and contracts
when heated, and which is substantially transparent to radiant
energy, thereby remaining substantially unchanged by radiant
energy. An absorbent material overlays at least a portion of the
film substrate. The absorbent material is sufficiently opaque to
radiant energy to absorb and convert radiant energy into heat
energy. This heat energy causes the heat sensitive indicia-former
carried by the film to undergo conversion from a first visual
condition to a second visual condition. This change in visual
condition preferably occurs at a temperature below that at which
the film is caused to shrink.
[0049] The invention is further directed to a method of preparing
and sealing beverage containers. According to this embodiment of
the invention, an open-top container is filled with a beverage. The
open-top container is then covered with the film of the invention.
The film material is then subjected to energy, which is converted
to heat energy. The heat energy causes the film material to shrink
to form a seal over the open top, and the indicia-former is
thereafter exposed to heat sufficient to transform it from the
first visual condition to the second visual condition.
Alternatively, the sealing step can be carried out simultaneously
with or after the step of transforming the indicia former from a
first visual condition to a second visual condition.
EXAMPLE 1
[0050] A test was performed to confirm the ability of the
combination of the thermochromic and absorbing inks to form in the
indicia-former after it undergoes exposure to radiant energy in the
form of a lightbulb. A 75-gauge CLYSAR film manufactured by Bernis
Corporation was printed with an absorbent material consisting of a
black ink that contains carbon pigment sold under the name Brazilia
TN15787 by Coates Ink, a division of Sun Chemical. Then a white ink
sold by Coates Ink under the trade name Lunar TN12316 was printed
over discrete portions of the black layer of absorbent material to
provide indicia areas showing the various types of drink options,
resulting in each indicia area having a gray color which serves to
provide a contrasting background for the indicia formed upon
conversion to the second visual condition. Next, an indicia-former
composed of a white thermochromic ink manufactured by Sherwood
Technologies, LLD, Nottingham, UK, under the trade name Sherwood
Type 90 was printed over each gray-colored indicia area. The
resulting indicia areas were gray in color.
[0051] The film was exposed to a 350-watt halogen lightbulb,
causing the thermochromic ink to turn from gray to black. The
change in color of the indicia area was visible, but it was felt
that the contrast could be improved as described in EXAMPLE 2
EXAMPLE 2
[0052] The test procedure used in EXAMPLE 1 was repeated, except
that additional white ink was provided for contrast on each indicia
area, resulting in the indicia area having a white appearance
relative to the gray appearance in EXAMPLE 1 above. Then the
thermochromic indicia-former was added over the white layer and
exposed to the same 350-watt halogen lightbulb, causing the
indicia-former to change from white to black. Accordingly, the
color change of the thermochromic ink in EXAMPLE 2 was more
pronounced and easier to see.
EXAMPLE 3
[0053] The film substrate was treated with the absorbent ink for
radiant energy absorption, white ink to provide contrast and
thermochromic ink as the indicia-former, as in EXAMPLE 1. The
treated film was exposed to the 350-watt halogen lightbulb for
one-half second at a distance of 0.5 inch. Following such exposure,
the thermochromic layer changed from white to black.
EXAMPLE 4
[0054] A packaging film was prepared as in EXAMPLE 3. The period of
exposure of the treated film to the 350-watt halogen lightbulb at a
distance of 0.5 inch was changed from 0.5 second to 1.0 second. The
resulting heat melted the film, causing a hole to form in the film,
indicating over-treatment.
EXAMPLE 5
[0055] The film of EXAMPLE 1 was exposed to radiant energy from a
100-watt halogen bulb for one-quarter of a second. The halogen bulb
was operating at 30% of full power (duty cycle energized 30% of the
time during activation period). Radiant energy was applied to the
film at a distance of 0.5 inch. These conditions resulted in the
transformation of the thermochromic ink from white to black,
without any noticeable deleterious effect on the thermochromic ink
layer.
EXAMPLE 6
[0056] The film of EXAMPLE 2 was exposed to radiant energy from a
100-watt halogen bulb for one-quarter of a second. The halogen bulb
was operating at 30% of full power (duty cycle energized 30% of the
time during activation period). Radiant energy was applied to the
film at a distance of 0.5 inch. These conditions resulted in the
transformation of the thermochromic ink from white to black,
without any noticeable deleterious effect on the thermochromic ink
layer.
EXAMPLE 7
[0057] The film of EXAMPLE 1 was treated with the black energy
absorbent ink, two layers of white ink for contrast and
thermochromic ink. The thermochromic ink was applied in the
configuration of a circle enclosing the letter "x." The film was
exposed to radiant energy from a 100-watt halogen bulb for
one-quarter of a second. The halogen bulb was operating at 30% of
full power (duty cycle energized 30% of time during activation
period). Radiant energy was applied to the film of a distance of
0.5 inch. The condition resulted in the transformation of the
thermochromic ink from white to black, resulting in a very distinct
circle enclosing the letter "x."
[0058] Other embodiments of the invention will be apparent to those
skilled in the art from consideration of the specification and
practice of the invention disclosed herein. It is intended that the
specification and examples be considered as exemplary only with a
true scope and spirit of the invention being indicated by the
following claims.
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