U.S. patent application number 16/162591 was filed with the patent office on 2019-02-14 for activatable adhesive, labels, and related methods.
The applicant listed for this patent is Avery Dennison Corporation. Invention is credited to Rishikesh K. BHARADWAJ, David N. EDWARDS, Dong-Tsai HSEIH, Kourosh KIAN, Sou Phong LEE, Johannes LENKL, Kai LI, Prakash MALLYA.
Application Number | 20190051219 16/162591 |
Document ID | / |
Family ID | 49210665 |
Filed Date | 2019-02-14 |
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United States Patent
Application |
20190051219 |
Kind Code |
A1 |
KIAN; Kourosh ; et
al. |
February 14, 2019 |
Activatable Adhesive, Labels, and Related Methods
Abstract
An activatable adhesive that is formulated to readily absorb
energy from a given radiation source, an activatable adhesive label
that incorporates such an activatable adhesive, a system for
activating such labels, and related methods and uses are described.
The activatable adhesive includes a plasticizer, a tackifier, and
an adhesive base polymer that includes butyl acrylate, styrene,
methyl methacrylate, methacrylic acid, and acrylic acid.
Inventors: |
KIAN; Kourosh; (Altadena,
CA) ; LEE; Sou Phong; (Arcadia, CA) ; HSEIH;
Dong-Tsai; (Arcadia, CA) ; EDWARDS; David N.;
(Pasadena, CA) ; LENKL; Johannes; (Freising,
DE) ; BHARADWAJ; Rishikesh K.; (Temple City, CA)
; MALLYA; Prakash; (Sierra Madre, CA) ; LI;
Kai; (Diamond Bar, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Avery Dennison Corporation |
Glendale |
CA |
US |
|
|
Family ID: |
49210665 |
Appl. No.: |
16/162591 |
Filed: |
October 17, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15591364 |
May 10, 2017 |
10140891 |
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16162591 |
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13892443 |
May 13, 2013 |
9653006 |
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15591364 |
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13119006 |
Mar 15, 2011 |
9200186 |
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PCT/US10/47428 |
Sep 1, 2010 |
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13892443 |
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12561349 |
Sep 17, 2009 |
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13119006 |
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61097822 |
Sep 17, 2008 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C09J 7/35 20180101; C09J
2400/226 20130101; G09F 3/02 20130101; Y10T 428/2891 20150115; C08K
5/10 20130101; C08K 5/12 20130101; Y10T 428/2848 20150115; Y10T
428/28 20150115; C08K 5/0016 20130101; C09J 2433/00 20130101; C09J
133/02 20130101; C09J 7/29 20180101; C09J 2400/163 20130101; G09F
2003/025 20130101; Y10T 428/24355 20150115; Y10T 428/2843 20150115;
C09J 125/14 20130101; G09F 2003/0201 20130101; G09F 3/10 20130101;
Y10T 428/2813 20150115; C09J 133/10 20130101; C09J 2203/334
20130101; C09J 2301/408 20200801; C08K 3/013 20180101; C09J
2400/283 20130101; C08K 3/04 20130101; C09J 7/385 20180101; C09J
133/08 20130101; G09F 2003/0241 20130101; C09J 2301/41
20200801 |
International
Class: |
G09F 3/10 20060101
G09F003/10 |
Claims
1. An aqueous adhesive composition which is activatable by exposure
to IR radiation and exhibits pressure sensitive adhesive properties
once activated by IR radiation or by heating, the adhesive
composition comprising (i) an emulsion base copolymer exhibiting a
glass transition temperature Tg above 25.degree. C. and a weight
average molecular weight within a range of from 10,000 Daltons to
150,000 Daltons, (ii) a solid plasticizer for such copolymer
exhibiting a melting point above 40.degree. C., and (iii) a high
softening point tackifier.
2. An adhesive comprising: an adhesive base polymer including at
least one lower alkyl acrylate, styrene, methyl methacrylate,
methacrylic acid, acrylic acid, at least one multifunctional
monomer, and at least one chain transfer agent; a plasticizer; and
atackifier.
3. The adhesive according to claim 2 wherein the adhesive
comprises: from about 20% to about 35% of an adhesive base polymer;
from about 50% to about 75% of a plasticizer; and from about 5% to
about 20% of a tackifier.
4. The adhesive according to claim 2 wherein the adhesive base
polymer includes: from about 5% to about 50% of at least one lower
alkyl acrylate; from about 20% to about 85% of styrene; from about
1% to about 35% methyl methacrylate; from about 0.5% to about 5%
methacrylic acid; from about 0.5% to about 5% acrylic acid; from
about 0% to about 5.0% of at least one multifunctional monomer; and
from about 0% to about 5.0% of at least one chain transfer
agent.
5. The adhesive according to claim 2 wherein the at least one lower
alkyl acrylate is selected from the group consisting of methyl
acrylate, butyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate,
and combinations thereof.
6. The adhesive according to claim 5 wherein the at least one lower
alkyl acrylate is butyl acrylate.
7. The adhesive base polymer according to claim 6 wherein: the
butyl acrylate is from about 9% to about 14% of the adhesive base
polymer; the styrene is from about 68% to about 80% of the adhesive
base polymer; the methyl methacrylate is from about 2% to about 6%
of the adhesive base polymer; themethacrylic acid is about 1% to
about 2% of the adhesive base polymer; the acrylic acid is about 1%
to about 2% of the adhesive base polymer; the multifunctional
monomer is from about 0.5% to about 2.5% of the adhesive base
polymer; and the chain transfer agent is from about 1.0% to about
4.0% of the adhesive base polymer.
8. The adhesive according to claim 2 wherein the adhesive is
white.
9. The adhesive according to claim 2 wherein the adhesive does not
include an additive selected from the group consisting of carbon
black, graphite, an ink, a dye, a pigment, and a colorant.
10. The adhesive according to claim 2 wherein the adhesive further
comprises at least one additive selected from the group consisting
of carbon black, graphite, an ink, a dye, a pigment, and a
colorant.
11. The adhesive according to claim 2 wherein the plasticizer is a
material selected from dicyclohexyl phthalate, glyceryltribenzoate,
diphenyl phthalate, 1,4-cyclohexane dimethanoldibenzoate, and
combinations thereof.
12. The adhesive according to claim 2 wherein the tackifier is
provided in the form of an aqueous resin ester dispersion.
13. The adhesive according to claim 2 wherein the plasticizer is
configured to melt after exposure to energy.
14. The adhesive according to claim 2 wherein the adhesive is
configured to be activated by exposure to energy for less than one
second.
15. The adhesive according to claim 13 wherein the energy is
selected from the group consisting of NIR energy, MWIR energy, IR
energy, microwave energy, inductive heating energy, visible light
energy, radiant heat energy, and UV energy.
16. The adhesive according to claim 14 wherein the energy has a
peak wavelength from approximately 0.8 micrometer to approximately
3.0 micrometers.
17. The adhesive according to claim 2 wherein: the adhesive is
activatable; the adhesive has a tackiness; and the adhesive's
tackiness is maintained for at least approximately two minutes
after the adhesive is activated.
18. The adhesive of claim 14 wherein the adhesive exhibits an open
time of from 0.1 second to 72 hours.
19. The adhesive of claim 14 wherein the adhesive upon activation,
exhibits an initial tack to a substrate of at least 1.0 Newton.
20. The adhesive of claim 19 wherein the substrate is selected from
the group consisting of cardboard and steel.
21. The adhesive of claim 14 wherein the adhesive upon activation,
exhibits an optical clarity having less than 10% haze.
22. The adhesive of claim 14 wherein the adhesive upon activation,
is clear.
23. The adhesive of claim 22 wherein the adhesive remains clear for
at least 1 year.
24. The adhesive of claim 2 wherein the adhesive base polymer has a
weight average molecular weight within a range of 10,000 Daltons to
150,000 Daltons.
25. The adhesive of claim 14 wherein the adhesive is activated by
exposure to electromagnetic radiation having a wavelength of from
0.1 micrometers to 10 micrometers.
26. The adhesive of claim 14 wherein the intensity of the
electromagnetic radiation is from about 100 kW/m.sup.2 to about 800
kW/m.sup.2.
27. A system that is configured to facilitate the application of an
activatable label to an item, the system comprising: a means for
emitting energy; and one or more actuators that are configured to:
receive the activatable label, transport the activatable label
through the emitted energy, and transport the activatable label to
a position where the activatable label is applied to the item;
wherein the activatable label includes an adhesive having: i. an
adhesive base polymer including butyl acrylate, styrene, methyl
methacrylate, methacrylic acid, acrylic acid, at least one
multifunctional monomer, and at least one chain transfer agent, ii.
a plasticizer, and iii. a tackifier.
28. The system according to claim 27 wherein the one or more
actuators is selected from the group consisting of a blower system,
a conveyor belt, a paddle, a carrier sheet, a plunger, a vacuum
drum, a roller, a vacuum belt, and a vacuum head.
29. The system according to claim 27 wherein the item is selected
from the group consisting of a bottle, a can, a container, a
vessel, a bag, a pouch, an envelope, a parcel, and a box.
30. The system according to claim 27 wherein the activatable label
is one of a stack of precut activatable labels.
31. A method for activating a label, the method comprising:
providing the label wherein the label has a first surface that is
coated with an activatable adhesive, the activatable adhesive
including: i. an adhesive base polymer including butyl acrylate,
styrene, methyl methacrylate, methacrylic acid, and acrylic acid,
ii. a plasticizer, and iii. a tackifier; providing a source of
energy configured to output radiant energy; and exposing the label
to the radiant energy that is output from the source of energy so
the first surface of the label becomes tacky.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a division of U.S. patent
application Ser. No. 15/591,364 filed May 10, 2017, which is a
continuation of U.S. patent application Ser. No. 13/892,443 filed
May 13, 2013, now U.S. Pat. No. 9,653,006, which is a division of
U.S. patent application Ser. No. 13/119,006 filed Mar. 15, 2011,
now U.S. Pat. No. 9,200,186, which is a 371 of International Patent
Application No. PCT/US2010/047428 filed Sep. 1, 2010, which is a
Continuation-In-Part of U.S. patent application Ser. No. 12/561,349
filed Sep. 17, 2009, and further claims the benefit of U.S.
Provisional Patent Application No. 61/097,822 filed Sep. 17, 2008,
all of which are incorporated herein by reference in their
entireties.
FIELD OF THE INVENTION
[0002] The present invention generally relates to adhesives and
labels. More specifically, the invention relates to activatable
adhesives and activation of label adhesives using radiation and
temperature changes.
BACKGROUND OF THE INVENTION
[0003] Traditional pressure sensitive labels are supplied to the
user affixed to a release liner. These release liners are typically
silicone coated, and, as such, are not usable as sources for
recycled paper. In an effort to reduce cost, improve efficiencies,
and reduce environmental impact, consumer demand for labels without
liners has increased in recent years. The most common forms of
these labels are "linerless labels" and "activatable labels".
[0004] "Linerless labels" have a sticky side and a release-coated
side so they can be wound upon themselves into rolls. The use of
these linerless labels requires either preprinting or special
printers that are configured to print on release coating. The
equipment used to manipulate linerless labels includes special
rollers and platens that are configured to contact the sticky side
of the labels. Despite many improvements in this equipment,
adhesive buildup still occurs in various sections of the equipment.
Because of these shortcomings, and also the high price of the final
sticky "linerless" product, these linerless labels have not
received wide customer acceptance.
[0005] "Activatable labels" are supplied to the end user in a
non-tacky state, and then the labels are activated, i.e., the
label's adhesive is activated, to a tacky state just prior to
application to the intended object. Most often, activatable labels
are printed with indicia prior to activation. Known activation
schemes include the use of ultraviolet ("UV") energy to heat the
adhesive (see U.S. Pat. No. 6,492,019 to Shipston et al.), corona
treatment to activate the surface (see U.S. Pat. No. 6,326,450 to
Shipston et al.), radiant heat to warm the adhesive (see U.S. Pat.
No. 6,500,536 to Yamada et al.), moisture to activate a rewettable
adhesive (see U.S. Pat. No. 6,803,100 to Hintz et al.),
microencapsulating an activator material, which can then be crushed
to allow the activator to mix with the rest of the formulation and
activate the adhesive (see U.S. Pat. No. 7,026,047 to Krolzig),
overcoating the adhesive with a detackifier layer, which is later
removed by heat or mechanical means (see U.S. Pat. No. 5,569,515 to
Rice et al.), and ultrasound energy to activate the adhesive (see
U.S. Pat. No. 5,702,771 to Shipston et al.).
[0006] By far, the most common activation scheme utilizes heat
activation, i.e., the activation of the label using heat. For heat
activation, various techniques have been proposed. These include
the use of the following: heated drums or rollers (see U.S. Pat.
Nos. 5,749,990 and 5,480,502 to Rello et al.), direct contact with
the heating element (see U.S. Pat. Nos. 6,388,692 to Iwata et al.
and 6,501,495 to Ichikawa et al.), microwave energy (see U.S. Pat.
No. 3,461,014 to James), heated belts in contact with the adhesive
(see U.S. Pat. Nos. 4,468,274 to Adachi and 6,031,553 to Nagamoto
et al.), and infrared ("IR") and near infrared radiation ("NIR")
(see U.S. Pat. Nos. 3,247,041 to Henderson and 4,156,626 to
Souder). In addition, general methods for heating using radio
frequency ("RF") energy, inductive heat, radiant heat, and visible
light also are well known and could be applied to this list of
activation methods. These techniques have all proven useful at
low-speed operations, but as application speeds increase, these
methods all suffer in that the exposure times of the labels to the
heating elements must somehow be increased in order to gain
sufficient heating. Either the size or the cost of the units
capable of supplying sufficient heating has thwarted high-speed
applications.
[0007] One way to overcome the need for larger or longer heaters is
to increase the ability of the adhesive to absorb the energy from
the heating devices. U.S. Pat. Nos. 4,156,626 to Souder and
6,043,190 to Ichikawa et al., and U.S. Patent Application
Publication Numbers 2003/0041963 and 2004/0166309 to Gong et al.
all describe the use of NIR absorbers to increase the energy
absorbance by adhesives. Hence, the use of NIR absorbers and
high-intensity NIR lamps might appear to be a viable route for
activating the adhesive. Although satisfactory in many respects,
disadvantages exist involving currently known activatable labels,
labeling systems, and related methods.
[0008] Hence, there remains a need for a label without a liner and
a related method of high-speed activation of the label. The present
invention satisfies these needs.
SUMMARY OF THE INVENTION
[0009] The embodiments of the present invention described below are
not intended to be exhaustive or to limit the invention to the
precise forms disclosed in the following detailed description.
Rather, the embodiments are chosen and described so that others
skilled in the art may appreciate and understand the principles and
practices of the present invention.
[0010] An exemplary embodiment of the present invention is an
aqueous adhesive composition which is activatable by exposure to IR
radiation and which exhibits pressure sensitive adhesive properties
once activated by IR or by heating. The adhesive composition
comprises (i) an emulsion base copolymer exhibiting a glass
transition temperature Tg above 25.degree. C. and a weight average
molecular weight within a range of from 15,000 Daltons to 100,000
Daltons, (ii) a solid plasticizer for such copolymer exhibiting a
melting point above 40.degree. C., and (iii) a high softening point
tackifier.
[0011] Another exemplary embodiment is an adhesive that includes a
plasticizer, a tackifier, and an adhesive base polymer that
includes a lower alkyl acrylate such as butyl acrylate, styrene,
methyl methacrylate, methacrylic acid, and acrylic acid.
[0012] Generally, the present invention provides an adhesive system
that comprises from about 20% to about 35% of an adhesive base
polymer, from about 50% to about 75% of a plasticizer, and from
about 5% to about 20% of a tackifier.
[0013] Preferably, the adhesives comprise from about 24% to about
30% of an adhesive base polymer, from about 56% to about 68% of a
plasticizer, and from about 8% to about 16% of a tackifier.
[0014] In a more detailed embodiment, particular formulations are
provided for the adhesive systems. In one preferred composition,
the adhesive comprises about 28.6% of an adhesive base polymer,
about 57.1% of a plasticizer, and about 14.3% of a tackifier. In
another preferred composition, the adhesive comprises about 25% of
an adhesive base polymer, about 66% of a plasticizer, and about 9%
of a tackifier.
[0015] Generally, in one embodiment, the invention provides an
adhesive base polymer that includes from about 10% to about 50% of
at least one lower alkyl acrylate, from about 20% to about 85%
styrene, from about 1% to about 35% methyl methacrylate, from about
0.5% to about 5% methacrylic acid, from about 0.5% to about 5%
acrylic acid, from about 0% to about 5.0% of at least one
multifunctional monomer, and from about 0% to about 5.0% of at
least one chain transfer agent.
[0016] In a more detailed aspect, the adhesive base polymer
comprises from about 12% to about 48% of at least one lower alkyl
acrylate, from about 23% to about 78% styrene, from about 3% to
about 30% methyl methacrylate, from about 1% to about 2%
methacrylic acid, from about 1% to about 3% acrylic acid, from
about 0.5% to about 2.5% of at least one multifunctional monomer,
and from about 1.0% to about 4.0% of at least one chain transfer
agent.
[0017] In another detailed embodiment, particular formulations are
provided for the adhesive base component. In one preferred
composition for the adhesive base polymers, the butyl acrylate is
about 37.2% of the adhesive base polymer, the styrene is about
29.3% of the adhesive base polymer, the methyl methacrylate is
about 29.3% of the adhesive base polymer, the methacrylic acid is
about 1.7% of the adhesive base polymer, and the acrylic acid is
about 2.5% of the adhesive base polymer. In another embodiment, the
butyl acrylate is about 48.0% of the adhesive base component, the
styrene is about 23.9% of the adhesive base component, the methyl
methacrylate is about 23.9% of the adhesive base component, the
methacrylic acid is about 1.7% of the adhesive base component, and
the acrylic acid is about 2.5% of the adhesive base component. In
still another embodiment, the butyl acrylate is about 12.8% of the
adhesive base component, the styrene is about 77.6% of the adhesive
base component, the methyl methacrylate is about 3.2% of the
adhesive base component, the methacrylic acid is about 1.2% of the
adhesive base component, and the acrylic acid is about 1.7% of the
adhesive base component, a multifunctional monomer amount is 1.5%,
and a chain transfer agent amount is 1.9%.
[0018] In other more detailed features of the invention, the
adhesive is white. Also, in other features, the adhesive does not
include and so, is free from carbon black, graphite, an ink, a dye,
a pigment, and/or a colorant. In addition, the plasticizer can be
UNIPLEX 250 or dicyclohexyl phthalate. In addition, the tackifier
can be TACOLYN 3400 or ARAKAWA SE-E 650.
[0019] In other more detailed features of the invention, the
plasticizer is configured to melt upon and/or after exposure to
energy. Also, the adhesive can be configured to be activated by
exposure to energy for less than one second. In addition, the
adhesive can be configured to be activated by exposure to energy
for less than 0.3 second.
[0020] In other more detailed features of the invention, the energy
is NIR, short IR energy, Mid Wave IR energy, IR energy, microwave
energy, RF energy, inductive heat energy, visible light energy,
radiant heat energy, or UV energy. Also, the IR energy can have a
peak wavelength from approximately 0.8 micrometer to approximately
3.0 micrometers. In addition, the energy can have a peak wavelength
from approximately 1.2 micrometers to approximately 2.5
micrometers.
[0021] In other more detailed features of the invention, the
adhesive is activatable, the adhesive has a tackiness, and the
adhesive's tackiness is maintained for at least approximately two
minutes after the adhesive is activated.
[0022] Another exemplary embodiment is a label that includes a
facestock layer and an adhesive layer that is coupled to the
facestock layer. The adhesive layer includes a plasticizer, a
tackifier, and an adhesive base polymer that includes butyl
acrylate, styrene, methyl methacrylate, methacrylic acid, and
acrylic acid.
[0023] In other more detailed features of the invention, the label
is configured to be exposed to radiant energy, the radiant energy
has a wavelength and an intensity that results in the adhesive
layer becoming tacky after exposure to the radiant energy, and the
facestock layer is not discolored after the exposure of the label
to the radiant energy. Also, the facestock layer can be made of
paper, polymer film, metallized paper, metallized film, paper
backed foil, or metal foil.
[0024] In other more detailed features of the invention, the label
is configured to be applied to an item, and to be repositioned for
approximately one minute after the label is applied to the item.
Also, the adhesive layer can be activatable, have a tackiness, and
be configured to be applied to an item, so that after the label is
applied to the item, the adhesive layer's tackiness prevents the
label from inadvertently being removed from the item. In addition,
the label can be configured to be applied to an item, and after the
label is applied to the item, the label permanently bonds with the
item after approximately two hours.
[0025] Another exemplary embodiment is a label assembly comprising
a facestock layer and a heat activatable adhesive layer, and a
functional coating layer disposed between the adhesive layer and
the facestock layer.
[0026] Another exemplary embodiment is a label that includes a
facestock layer, an adhesive layer, and a reflective layer that is
coupled between the facestock layer and the adhesive layer.
[0027] Another exemplary embodiment is a label that includes a
facestock layer, an adhesive layer, and a barrier layer disposed
between the facestock layer and the adhesive layer.
[0028] And, another exemplary embodiment is a label that includes a
facestock layer, an adhesive layer, and a primer layer disposed
between the facestock layer and the adhesive layer.
[0029] In other more detailed features of the invention, the
adhesive layer of the various label assemblies includes a
plasticizer, a tackifier, and an adhesive base polymer including
butyl acrylate, styrene, methyl methacrylate, methacrylic acid, and
acrylic acid.
[0030] In other more detailed features of the invention, the label
is configured to be exposed to a radiant energy, the radiant energy
has a wavelength and an intensity that results in the adhesive
layer becoming tacky after exposure to the radiant energy, and the
facestock layer is not discolored after the exposure of the label
to the radiant energy. Also, the facestock layer can have a bottom
surface, and the label can include a reflective layer that is made
of a material that is applied as a coating to the bottom surface of
the facestock layer. In addition, the material of the reflective
layer can be gold, silver, aluminum, or copper. Furthermore, the
reflective layer can have a thickness of not greater than one
micron.
[0031] In other more detailed features of the invention, the
reflective layer has a reflectivity value, and the reflectivity
value is greater than approximately 90 percent. Also, the
reflective layer can underlie only a portion of the facestock
layer. In addition, the adhesive layer can have a first surface,
the reflective layer can have a second surface that is adjacent to
the first surface, and the second surface can be textured.
Furthermore, the second surface's texture can be configured to be
retroreflective.
[0032] In other more detailed features of the invention, the label
is configured to be exposed to a radiant energy, the radiant energy
has a wavelength and an intensity that results in the adhesive
layer becoming tacky after exposure to the radiant energy, and the
facestock layer is not discolored after the exposure of the label
to the radiant energy. Also, the facestock layer can have a bottom
surface, and the label can include a barrier layer that is made of
a material that is applied as a coating to the bottom surface of
the facestock layer. In addition, the material of the barrier layer
is selected so as to prevent or at least significantly reduce
discoloration of the facestock layer.
[0033] Another exemplary embodiment is a system that is configured
to facilitate the application of an activatable label to an item.
The system includes an energy source that is configured to emit
energy and one or more actuators that are configured to receive the
activatable label, transport the activatable label through the
emitted energy, and transport the activatable label to a position
where the activatable label is applied to the item. The activatable
label includes an adhesive having a plasticizer, a tackifier, and
an adhesive base polymer that includes butyl acrylate, styrene,
methyl methacrylate, methacrylic acid, and acrylic acid.
[0034] Another exemplary embodiment is a system that is configured
to facilitate the application of an activatable label to an item.
The system includes an energy source that is configured to emit
energy, a printer that is configured to print indicia on the
activatable label, and one or more actuators that are configured to
receive the activatable label, transport the activatable label past
the printer that then prints the indicia on the activatable label,
transport the activatable label through the emitted energy, and
transport the activatable label to a position where the activatable
label is applied to the item. The activatable label includes an
adhesive having a plasticizer, a tackifier, and an adhesive base
polymer that includes butyl acrylate, styrene, methyl methacrylate,
methacrylic acid, and acrylic acid.
[0035] In other more detailed features of the invention, the one or
more actuators is a blower system, a conveyor belt, a paddle, a
carrier sheet, a plunger, a vacuum drum, a roller, a vacuum belt,
or a vacuum head. Also, the item to receive the label can be a
bottle, a can, a container, a vessel, a bag, a pouch, an envelope,
a parcel, or a box. In addition, the activatable label can be one
of a stack of precut activatable labels.
[0036] An exemplary method according to the invention is a method
for applying a label with an activatable adhesive to an item. The
method includes providing a label that has a first surface that is
coated with an activatable adhesive, the adhesive including a
plasticizer, a tackifier, and an adhesive base polymer including
butyl acrylate, styrene, methyl methacrylate, methacrylic acid, and
acrylic acid. The method also includes providing the item that has
a second surface, providing a source of energy that is configured
to output radiant energy, exposing the first surface of the label
to the radiant energy that is output from the source of energy so
the first surface of the label becomes tacky, and placing the first
surface of the label in contact with the second surface of the
item.
[0037] In other more detailed features of the invention, the label
is pre-printed with indicia. Also, the method can further include
providing a printer that is configured to print an image on the
label, and printing the image on the label before the step of
exposing the label to the radiant energy. Also the method includes
providing a cutter that is configured to cut the dry label to a
desired length before the activation stage. In addition, the label
can include a facestock layer and an adhesive layer. The adhesive
layer includes the adhesive base polymer, the plasticizer, and the
tackifier, and the facestock layer is not discolored after the
exposure of the label to the radiant energy.
[0038] In other more detailed features of the invention, the step
of providing the label includes providing a plurality of labels,
the step of providing an item includes providing a plurality of
items, the step of exposing the label includes exposing at least
one of the plurality of the label to the radiant energy, and the
step of placing the label in contact with the item includes placing
one of the plurality of labels in contact with one of the plurality
of items at a rate greater than approximately 60 labels per minute.
Also, the step of placing the label in contact with the item
includes placing one of the plurality of labels in contact with one
of the plurality of items at a rate of less than or equal to
approximately 1,000 labels per minute.
[0039] Another exemplary method according to the invention is a
method for activating a label. The method includes providing a
label having a first surface that is coated with an activatable
adhesive, the activatable adhesive includes a plasticizer, a
tackifier, and an adhesive base polymer including butyl acrylate,
styrene, methyl methacrylate, methacrylic acid, and acrylic acid.
The method also includes providing a source of energy that is
configured to output radiant energy, and exposing the label to the
radiant energy that is output from the source of energy so the
first surface of the label becomes tacky.
[0040] In another exemplary embodiment, a system is provided for
printing and applying labels to articles. The system comprises a
printer unit, a thermal activation unit downstream of the printer
unit, and an applicator unit downstream of the thermal activation
unit. The thermal activation unit includes a label transport
assembly and one or more emitters that are configured to emit
radiation to labels. In particularly preferred aspects of this
system, unique sensor arrangements are utilized to assess whether
label degradation condition(s) are occurring. And, optional quartz
glass members are preferably used to improve safety and operability
of the system.
BRIEF DESCRIPTION OF THE DRAWINGS
[0041] These, as well as other features, aspects, and advantages of
this invention, will be more completely understood and appreciated
by referring to the following more detailed description of the
exemplary embodiments of the invention in conjunction with the
accompanying drawings.
[0042] FIG. 1 is a sectional view of a preferred embodiment
activatable label in accordance with the invention.
[0043] FIG. 2 is a diagram of an exemplary system in accordance
with the invention for printing, cutting, activating and applying
one or more labels to a container.
[0044] FIG. 3 is a diagram of an exemplary system for printing and
activating a stack of labels and applying them to a container.
[0045] FIG. 3A is a diagram of an exemplary system for performing a
print and apply type of label application.
[0046] FIG. 3B is a diagram of another preferred system for
applying a label with an activatable adhesive to an item.
[0047] FIG. 3C is a diagram of yet another preferred system for
applying a label with an activatable adhesive to an item.
[0048] FIG. 3D is a diagram of another preferred system for
applying a label with an activatable adhesive to an item.
[0049] FIG. 4 is a flowchart of an exemplary method for applying a
label with an activatable adhesive to an item.
[0050] FIG. 5 is a flowchart of an exemplary method for activating
a label according to the invention.
[0051] FIG. 6 is a flowchart of an exemplary method for printing,
cutting and applying a label with an activatable adhesive to an
item.
[0052] FIG. 6A is a flowchart of an exemplary method for applying a
label according to the invention.
[0053] FIG. 6B is a flowchart of another exemplary method for
applying a label according to the invention.
[0054] FIG. 7 is a sectional view of a label having a reflective
layer where the reflective layer is continuous according to an
embodiment of the invention.
[0055] FIG. 8 is a sectional view of another label having an
optional coating on the indicia bearing surface of the facestock
according to an embodiment of the invention.
[0056] FIG. 9 is a sectional view of another label having a
reflective layer where the reflective layer is patterned according
to an embodiment of the invention.
[0057] FIG. 10 is a top plan view of another label having a
reflective layer where the reflective layer is patterned according
to an embodiment of the invention.
[0058] FIG. 11 is a sectional view of yet another label having a
reflective layer where the reflective layer is retroreflective
according to an embodiment of the invention.
[0059] FIG. 12 is a top plan view of an exemplary rectangular label
having angular corners according to the invention.
[0060] FIG. 13 is a top plan view of an exemplary rectangular label
having rounded corners according to the invention.
[0061] FIG. 14 is a schematic illustration of a preferred
embodiment layered array in accordance with the invention.
[0062] FIG. 15 is a SPAT probe test of several preferred embodiment
adhesive compositions illustrating changes in tack over time after
activation.
[0063] FIG. 16 is a graph illustrating short term aging effects on
tack of an activated preferred embodiment adhesive according to the
invention.
[0064] FIG. 17 is a graph of MWIR activated preferred embodiment
adhesive using a high softening point tackifier.
[0065] FIG. 18 is a graph illustrating effect of dwell time on
adhesion of a preferred embodiment adhesive.
[0066] FIG. 19 is a graph illustrating effect of open time on the
tack of a preferred embodiment adhesive.
[0067] FIG. 20 is a graph illustrating the results of 90 degree
peel tests at 5.degree. C. using a preferred embodiment
adhesive.
[0068] FIG. 21 includes plots illustrating 90 degree peel tests
using the adhesive referenced in FIG. 20, in which the peel tests
were performed at 5.degree. C. and at room temperature.
[0069] FIG. 22 is a graph illustrating maximum temperatures of
label assemblies containing carbon black compared to a label
assembly free of carbon black, resulting after exposure to
radiation.
[0070] FIG. 23 is a graph illustrating various temperature and
dwell time plots illustrating the effect of using quartz glass
members.
[0071] Unless otherwise indicated, the illustrations in the above
figures are not necessarily drawn to scale.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0072] The present invention is now illustrated in greater detail
by way of the following detailed description, which represents the
best presently known mode of carrying out the invention. However,
it should be understood that this description is not to be used to
limit the present invention, but rather, is provided for the
purpose of illustrating the general features of the invention.
[0073] As previously noted, the use of energy absorbers in an
adhesive formulation is well documented, but in certain instances,
can result in darkly colored adhesives that are not compatible with
the aesthetic requirements of today's consumer market. As a result,
investigations were conducted to identify other absorbers that
possessed little or no color. By using common adsorption
spectroscopy including UV and IR spectral analysis, a comparison of
the absorption spectra of various adhesive components with the
emission spectra of various commercial energy sources was obtained.
By matching the absorbance range of the adhesive with the emission
range of the radiation or energy source, one can achieve maximum
energy transfer or substantially so, from the radiation source to
the adhesive. The radiation source can emit a broad spectrum of
energy wavelengths, typically with a peak wavelength, i.e. the
wavelength associated with the peak energy value in the spectrum.
As a result, it was possible to create adhesives that demonstrated
high absorption properties. These absorption properties allow for
the heat activation of the adhesives at faster rates while
requiring less energy to power the radiation sources and without
the drawback of having a darkly colored adhesive. Likewise, by
tuning the adhesive absorption to approximately match the radiation
emission, most of the energy that is radiated upon the label is
absorbed by the adhesive, leaving little energy remaining to couple
with the facestock or the indicia printed upon the facestock. If
energy is allowed to be absorbed by the facestock or the indicia,
the resulting heating of the facestock or the indicia can cause
discoloration of the facestock. While tuning the adhesive's
absorption to the radiation source lowers the occurrence of this
form of facestock discoloration, it has been discovered that, in
some cases, additional measures to avoid discoloration of the
facestock are warranted. In these cases, the discoloration can be
avoided by use of a functional layer such as a reflective layer
and/or a barrier layer between the adhesive and the facestock. It
is also contemplated that the functional layer could be in the form
of a primer layer.
[0074] It will be appreciated that although various preferred
embodiments of the invention are directed to providing adhesives
that are transparent, translucent, or white in appearance; the
invention is also applicable in providing adhesives that are opaque
or dark in appearance. Thus, for many applications in which the
former type of adhesives find use, such adhesives are preferably
free of additives, pigments, dyes, inks, and/or colorants such as
for example, carbon black or graphite. And for the latter type of
adhesives, such adhesives may contain one or more additives,
pigments, dyes, inks, and/or colorants such as for example carbon
black or graphite.
[0075] Another important attribute of the activatable adhesive is
the ability of the adhesive to stay in an activated state, i.e.,
the adhesive is in a tacky state, long enough to allow application
of the label to an item before the adhesive loses its tackiness.
This time period is commonly referred to as the "open time" of the
adhesive. Depending on the speed of application of the label to the
item, and the distance between the activating device and the point
where the label is applied to the item, this open time could be a
fraction of a second and as long as several minutes or more.
Embodiments of the adhesive can be repositionable for approximately
60 seconds, e.g., one minute, after application of the label to the
item so that minor adjustments can be made to the label's position
on the item immediately after application. Embodiments of the
adhesive form a permanent bond between the label and the item
within approximately two minutes, after activation of the label, so
that the label can not inadvertently be removed from, or
repositioned on, the item.
Adhesives
[0076] Generally, in accordance with the present invention, various
activatable adhesives or adhesive systems are provided as described
in greater detail herein. However, it will be appreciated that in
no way is the invention limited to the use of the particular
adhesive systems described herein. Preferably, the adhesive systems
utilize the particular adhesive base polymers described herein. The
adhesive systems generally comprise (i) an adhesive base polymer,
(ii) a plasticizer, and (iii) a tackifier. Typical and preferred
weight percent concentrations for each of these components are set
forth below in Table 1. It will be appreciated that the noted
weight percent concentrations are based upon the total weight of
components (i)-(iii). Thus, it is contemplated and expected that
the adhesive systems may include additional components and
additives in addition to components (i)-(iii) listed below in Table
1.
TABLE-US-00001 TABLE 1 Typical and Preferred Concentrations of
Components in Preferred Adhesive Systems Component Typical
Concentration Preferred Concentration Adhesive Polymer Base 20%-35%
24%-30% Plasticizer 50%-75% 56%-68% Tackifier 5%-20% 8%-16%
[0077] The preferred adhesive systems described herein generally
comprise an adhesive base polymer (described in greater detail
herein), a plasticizer which preferably, is in a solid crystalline
state below the application temperature, and a solid tackifier
which preferably, is also in a solid state below the application
temperature. The physical states of the adhesive material can be
switched between solid and non-solid by altering the temperature.
The open time of the adhesive can be controlled by adjusting the
ratio of the components, i.e. the adhesive polymer base, the
plasticizer, and the tackifier. The preferred activation
temperature is preferably within the range of from about 50.degree.
C. to about 120.degree. C. However, it will be understood that the
invention is not limited to adhesive systems exhibiting activation
temperatures within this range.
[0078] At the switching temperature of the adhesive, the properties
of adhesion and viscosity markedly change. Therefore, a pressure
sensitive adhesive system can be thermally switched from "off" to
"on" by using these strategies described herein. If such adhesive
system is then coated on a facestock at a temperature below the
designed switch temperature, the material is in its non-sticky
solid state. Thus, the label construction can be wound in a roll
form. During the application process, the temperature is increased
to the switching temperature so that the material will change to a
non-solid state and then exhibit its pressure sensitive adhesive
properties, which allow the label to be adhered to a substrate as
desired as a result of increased adhesion properties. If the
substrate exhibits a porous surface, the preferred embodiment
adhesive systems will flow into the pores and "stick" very well, as
a result of the interlocking effect even when the temperature is
reduced below that of the switching temperature of the
adhesive.
[0079] The formulation shown in Table 2, illustrates one exemplary
adhesive formulation wherein dicyclohexyl phthalate is used both as
a plasticizer and as an energy absorption agent. Another example of
a preferred plasticizer is glyceryl tribenzoate. Additional
examples of preferred plasticizers include diphenyl phthalate and
1,4-cyclohexane dimethanol dibenzoate.
TABLE-US-00002 TABLE 2 Exemplary Adhesive Formulation Weight %
Concentration Adhesive Polymer Base Butyl Acrylate ("BA") 37.2%
Styrene 29.3% Methyl Methacrylate ("MMA") 29.3% Methacrylic Acid
("MAA") 1.7% Acrylic Acid ("AA") 2.5% Heat-Activatable Adhesive:
Adhesive Polymer Base 28.6% Dicylclohexyl Phthlate (Plasticizer)
57.1% TACOLYN 3400 (Tackifier) 14.3%
[0080] As explained in greater detail herein, in forming the
adhesive polymer base it is preferred to utilize effective amounts
of one or more multifunctional monomers and one or more chain
transfer agents. A representative preferred multifunctional monomer
is ethylene glycol dimethacrylate (EGDMA). A preferred chain
transfer agent is n-dodecyl mercaptan (n-DDM).
[0081] The present invention also provides various preferred
embodiment adhesive polymer bases comprising (i) one or more lower
alkyl acrylates, (ii) styrene, (iii) methyl methacrylate (MMA),
(iv) methacrylic acid (MAA), (v) acrylic acid (AA), one or more
multifunctional monomers, and one or more chain transfer agents. In
one embodiment, typical and preferred concentrations for each of
these components are set forth below in Table 3 as follows. The
weight percent concentrations listed in Table 3 are based upon the
total weight of the adhesive polymer base. It will be understood
that the various adhesive base polymers described herein are merely
representative in nature. Although generally constituting preferred
embodiments of the invention, in no way is the invention limited to
the use of the particular adhesive base polymers described
herein.
TABLE-US-00003 TABLE 3 Typical and Preferred Concentrations of
Components in Adhesive Polymer Bases Typical Preferred Component
Concentration Concentration Lower Alkyl Acrylate 5%-50% 12%-48%
Styrene 20%-85% 23%-78% MMA 1%-35% 3%-30% MAA 0.5%-5% 1%-2% AA
0.5%-5% 1%-3% Multifunctional Monomer 0%-5% 0.5%-2.5% Chain
Transfer Agent 0%-5% 1.0%-4.0%
[0082] A wide array of lower alkyl acrylates can be used singly or
in combination for component (i) in the preferred embodiment
adhesive polymer base. For example, methyl acrylate, butyl
acrylate, ethyl acrylate, and 2-ethylhexyl acrylate could be used.
However, butylate acrylate and ethyl acrylate are generally
preferred with butyl acrylate being most preferred.
[0083] A wide array of styrene and styrene based materials can be
used for component (ii).
[0084] Similarly, for component (iii), it is generally preferred
that methyl methacrylate (MMA) be used. However, it will be
appreciated that other analogues and functionally equivalent
monomers could be used in conjunction with or instead of MMA.
[0085] The preferred monomer for component (iv) is methacrylic acid
(MAA). However, it will be appreciated that the invention includes
the use of other equivalent monomers in conjunction with or instead
of MAA.
[0086] And, although acrylic acid (AA) is noted for use as
component (v), it will be understood that the invention includes
the use of other equivalent monomers.
[0087] A wide array of multifunctional monomers or multifunctional
monomer agents can be used in the present invention. The
multifunctional monomers can be used to achieve cross-linking of
the base polymer. Representative examples of such multifunctional
monomers include, but are not limited to, difunctional monomers,
trifunctional monomers, and multifunctional monomers having more
than three active functional sites. Preferred examples of
difunctional monomers include, but are not limited to 1,4
butanediol diacrylate, polyethylene glycol (200) diacrylate, and
combinations thereof. Another preferred difunctional monomer is
ethylene glycol dimethacrylate (EGDMA). Preferred examples of
trifunctional monomers include, but are not limited to ethoxylated
(15) trimethylolpropane triacrylate, propoxylated (3) glycerol
triacrylate, and combinations thereof. Preferred examples of
multifunctional monomers having more than three active functional
sites include, but are not limited to, ethoxylated pentaerythritol
tetraacrylate, dipentaerythritol, pentaacrylates, and combinations
thereof. These and numerous other suitable multifunctional monomers
are commercially available from various suppliers such as Sartomer
of Exton, PA. Typical concentrations of multifunctional monomers
range from about 0 to about 5.0%, with from about 0.5% to about
2.5% being preferred, and from about 1.5% to about 2.0% being most
preferred.
[0088] Chain transfer agents when used in forming the adhesives,
are typically used at concentrations of from about 0 to about 5.0%,
and preferably from about 1.0% to about 4.0% (percentages are based
upon the total weight of monomers). Representative examples of
suitable chain transfer agents include, but are not limited to
n-dodecyl mercaptan (n-DDM), tert-nonyl mercaptan, isooctyl
3-mercaptopropionate, and combinations thereof. It will be
understood that in no way is the invention limited to these chain
transfer agents. Instead, a wide array of chain transfer agents can
be used. Suitable chain transfer agents are available commercially
such as from Sigma Aldrich of St. Louis, Mo. Most preferably, the
adhesive polymer bases include both (i) one or more multifunctional
monomer agents and (ii) one or more chain transfer agents.
[0089] In one embodiment, a particularly preferred adhesive polymer
base composition is set forth below in Table 3A.
TABLE-US-00004 TABLE 3A Preferred and Most Preferred Concentrations
of Components in an Adhesive Polymer Base Preferred Most Preferred
Component Concentration Concentration Butyl Acrylate 9%-14% 12.8%
Styrene 68%-80% 77.6% MMA 2%-6% 3.2% MAA 1%-2% 1.2% AA 1%-2% 1.7%
EGDMA 0.5%-2.5% 1.5% n-DDM 1.0%-4.0% 1.9%
[0090] The present invention provides a wide array of adhesives
having unique characteristics that enable the adhesives to be used
in numerous applications. One feature of the adhesives relates to
the relatively short time period required for activating the
adhesive, i.e. selectively changing the adhesive from a non-tacky
state to a tacky state. Fast activation times enable the adhesive
to be used in high speed labeling operations. Preferably, the
adhesives of the present invention can be activated within a time
period of about 0.3 seconds and generally activated in a time
period of less than 1 second, and more typically, less than 0.5
seconds. This time period is referred to herein as the adhesive's
"activation time."
[0091] As previously described herein, the adhesives, once
activated, remain in their activated state long enough to at least
allow application of a label carrying the adhesive to an item or
receiving substrate before the adhesive loses its tackiness. This
characteristic is described herein as the "open time" of the
adhesive. The adhesives of the invention preferably exhibit an open
time of at least from about 0.1 second to 10 minutes or longer. For
certain applications, the adhesives can be tailored to exhibit
relatively long open times, such as up to 72 hours or longer.
Typically, the adhesives of the invention exhibit open times of
from 10 seconds to 60 seconds.
[0092] Once the adhesives of the invention are activated, i.e.
while in their "open" and tacky state, the adhesives exhibit
relatively high tackiness. For example, the adhesives exhibit an
initial peak tack to a substrate such as cardboard or steel of at
least about 1.0 Newton, and preferably at least about 1.25 Newtons.
As described in conjunction with the examples presented herein,
typically, the preferred embodiment adhesives exhibit initial peak
tack values in the range of from 1.0 Newton to 2.0 Newtons. These
tack values are measured using SPAT, which is described in detail
herein. Preferably, these tack values are with regard to the
substrates as described herein. However, it will be appreciated
that the present invention is not limited to adhesives that exhibit
these tack values in association with the substrates described
herein. That is, it is contemplated that the invention includes
adhesives exhibiting these tack values in association with other
substrates and substrate materials not expressly described herein.
Furthermore, it is generally preferred that upon activation of the
adhesive, the tackifier softens and is in a flowable state.
[0093] In addition, in certain embodiments, the adhesives of the
present invention are generally clear after activation to allow the
passage of light without any detrimental absorbance. Preferably the
adhesives, once activated, remain in a clear or at least
substantially clear state for relatively long time periods and
preferably for at least 1 year, and more preferably longer than 1
year. It will also be understood that in other embodiments of the
invention, the adhesives may contain one or more pigments, dyes,
inks, colorants or the like such as for example, carbon black or
graphite. In the event that the adhesive contains carbon black or
graphite, typical concentrations range from about 0.01% to about
0.1% and preferably from about 0.02% to about 0.08%, based on wet
weight. In certain applications, a concentration of about 0.05% of
carbon block is used. A wide array of commercially available
sources of carbon black may be used. Preferably, carbon black from
Cabot Corporation of Boston, Mass. is utilized. Another preferred
carbon black is available under the designation AURASPERSE W-7012,
available from BASF Corporation of Florham Park, N.J.
[0094] The present invention adhesives, e.g. those for linerless
label applications, can be solvent based, water based such as
emulsion adhesives, hot melt, or UV curable adhesives, in which an
adhesive base polymer is blended with other adhesive components
such as a solid plasticizer, and/or a solid tackifier to yield a
linerless adhesive that is heat activatable, and particularly, a
light activatable adhesive such as NIR activatable adhesive
formulation.
[0095] Additional aspects of the preferred embodiment adhesives are
as follows. A typical range of average molecular weight of the
adhesive base polymer is from about 10,000 Daltons to about 150,000
Daltons. A preferred range is from about 15,000 Daltons to about
100,000 Daltons, with a range of from about 20,000 Daltons to about
40,000 Daltons being most preferred. A lower molecular weight base
polymer is generally preferred because such polymer can be
activated faster than a corresponding base polymer having a higher
molecular weight.
[0096] The adhesive base polymers also exhibit certain glass
transition temperatures, Tg. Although the Tg of the base polymer
depends upon pressure and temperature requirements of the process,
and pressure and temperature conditions which the product may
encounter, a typical Tg range is from about 20.degree. C. to about
100.degree. C. A preferred Tg range is from about 55.degree. C. to
about 80.degree. C. And, a most preferred range for the glass
transition temperature Tg of the base polymer is from 60.degree. C.
to 75.degree. C.
[0097] It is also preferred that when forming the adhesives, after
melting, the plasticizer remains in a liquid or flowable form for
an extended period of time. The temperatures at which the
plasticizers exist in a liquid or flowable state are typically from
50.degree. C. to 120.degree. C.
[0098] As a result of the particular formulation and selection of
components, many of which have particular properties and
characteristics, the preferred embodiment adhesives remain tacky in
a temperature range of from about -10.degree. C. to about
50.degree. C. and preferably from ambient temperature to about
45.degree. C. The preferred adhesives typically remain tacky for
time periods of from about 0.1 seconds to about 2 weeks. However,
it will be appreciated that the invention is not limited to these
particular time periods. For example, adhesives can be formulated
which remain tacky for periods longer than 2 weeks. Many of the
preferred adhesives exhibit remarkably long open times, i.e. the
period of time during which the adhesive is in a tacky state.
[0099] In accordance with the present invention, it is found that,
by controlling various factors including the molecular weight and
molecular weight distribution of the base polymer, as well as the
level of the multifunctional monomer of the base polymer by using a
combination of multifunctional monomer and chain transfer material,
a heat switchable adhesive that has superior properties of fast
activation, high tack, long open time, and long lasting clarity is
obtained. Upon heating, the activatable adhesive behaves as a
typical pressure sensitive adhesive, and the property of tack can
be maintained for a prolonged period of time, which allows the
adhesive material to flow or wet-out on the targeted substrate
surface for enhancing the adhesion. Furthermore, the adhesive
materials in this invention are inherently activatable with Near IR
radiation, which leads to a short activation time for fast line
speed.
[0100] The base polymers of the preferred adhesives of the
invention typically exhibit a polydispersity index of from about
2.0 to about 10.0, and preferably from 2.0 to 4.0. However, it will
be appreciated that the base polymers of the adhesives of the
invention include polymeric systems exhibiting polydispersities
less than 2.0 and greater than 10.0.
Labels, Additional Layers, Methods for Applying, and Equipment
[0101] FIG. 1 shows an exemplary activatable label construction 100
where a 10 mil facestock 110 (for example, the paper facestock used
is APPLETON C1S LITHO 60 lb, by Appleton of Appleton, Wis.) is
coated with a 1 mil layer of adhesive 120, the formulation of which
is described in Table 2. The preparation of such label
constructions is detailed, for example, in U.S. Pat. No. 4,745,026
to Tsukahara et al.
[0102] These labels 100 are typically printed with indicia 130
prior to activation. Indicia can include, for example, alphanumeric
data/information and/or graphical images. Printing techniques are
commonly known and include letterpress, laser, offset, gravure,
flexographic, silk screen, and digital methods. Digital printing
techniques can include, for example, ink jet, Xerographic, thermal,
and electrographic techniques. To activate and apply the labels to
an item, the labels are typically placed on a delivery device or
actuator. These delivery devices include blower systems (see U.S.
Pat. No. 4,784,714 to Shibata), conveyor belts (see U.S. Pat. No.
5,895,552 to Matsuguchi), paddles (see U.S. Pat. No. 5,922,169 to
Chodacki), plungers (see U.S. Pat. No. 6,006,808 to Ewert et al.),
carrier sheets (see U.S. Pat. No. 7,029,549 to Von Folkenhausen et
al.), vacuum drums (see U.S. Pat. No. 6,899,155 to Francke et al.),
rollers (see U.S. Pat. No. 5,964,975 to Hinton), and vacuum heads
or belts (see U.S. Pat. No. 6,471,802 to Williamson). The items to
which a label can be applied can include, for example, boxes,
parcels, envelopes, pouches, bags, vessels, containers, cans, and
bottles.
[0103] The delivery device or actuator receives the label 100, then
transports the label such that the adhesive 120 side of the label
is exposed to an activation device, which employs an activation
scheme as previously noted. In an example embodiment, the
activation scheme can include the exposure of the label to IR
energy having a peak wavelength from approximately 0.8 micrometers
to approximately 3 micrometers. Multiple delivery devices can be
used in sequence to transport the label from its unactivated state
to attachment to an item. For example, the delivery devices can
include one or more actuators that are configured to receive the
label, transport the label through the radiant energy, and
transport the label to a position where the label is applied to the
item. Examples of the one or more actuators include a blower
system, a conveyor belt, a paddle, a carrier sheet, a plunger, a
vacuum drum, a roller, a vacuum belt, and a vacuum head.
[0104] In an embodiment, labels 100 are activated using a ten-inch
long NIR unit by Advance Photonics Technology AG of Bruckmuhl,
Germany with emitters that each are configured to emit from
approximately 200 kW/m.sup.2 to 800 kW/m.sup.2 irradiance
delivering up to 4000 kW/m.sup.2 mostly around the peak wavelength
of 0.8 micrometer. The same activation rates in excess of 200
labels/minute were also obtained using a Mid Wave IR ("MWIR") unit
(Model M110) by Heraeus Noblelight GmbH of Keinostheim, Germany
that include two twin tube carbon emitters (Model #45134293) with
short response times of 1-2 second. Short response times are
advantageous because the unit(s), i.e., the energy source(s) that
are part of the activation device(s), can be turned ON and OFF at a
fast rate, for example, a rate of once every second or two seconds.
Energy savings result from avoiding the need to leave the unit(s)
ON continuously. Because of the high energy density provided by the
unit(s), the unit(s) need only be turned ON for a limited period of
time to activate the adhesive 120. Depending on the dimensions of
each label, exposure times of the adhesive to the radiation can be
for less than one second, and typically range from approximately
0.1 second to approximately 0.5 second. The same high activation
rates in excess of 200 labels/min were also obtained also using
another type of Mid Wave IR referred to as twin tube Fast Mid Wave
by Heraeus Noblelight GmbH radiating at slightly shorter
wavelengths with a peak at 1.5 um. The response time is around 1
second for these emitters. They are narrower than carbon types
giving higher energy densities. The selection of the type of
emitter depends upon a variety of factors, and particularly is a
trade off between high energy densities, e.g. highest absorption by
the adhesive and lowest absorption by the printed indicia, or
controlled penetration into the structure and fastest ON/OFF
cycles. Other factors especially relating to safety of using these
high power lamps in industrial applications need to be taken into
account when designing the activation system.
[0105] FIG. 2 shows an exemplary embodiment of a system 140 for a
Cut and Stack type of label application, where a stack of precut
activatable labels 150 are activated and affixed to items, e.g.,
containers 160. Each of the labels 100 are picked up by a vacuum
drum 180 such that the label's adhesive layer 120 is not in contact
with the vacuum drum, and the vacuum drum transports the labels
past a NIR or MWIR source 200, which activates the labels, in
particular, the labels' adhesive. The activated labels are then
transported to the items where they are affixed to the items.
Referring additionally to FIG. 1, in one embodiment, the labels are
preprinted with indicia on the face 210 of the label.
[0106] One advantage of such a system 140 is that the system uses
pre-coated and dried adhesive 120, which covers the edges 220 of
the label 100 as evenly as other areas on the labels. Current Cut
and Stack technology, which is generally known in the art, uses wet
applied glue, which is not always well applied near the edge of a
label. The poor alignment of the glue with the edge of the label
can result in curling of label's edges where the adhesive coverage
is not constant. This curling of the label's edges and the
resulting lifting of the edges is referred to as "flagging". This
often results in a label that, after application to an item, does
not adhere to the item near the label's edge, and thus, the label
is subject to tearing during transport and use.
[0107] Another advantage of such a system 140 is that the system
allows for short changeover times. Current Cut and Stack technology
requires special glue application feet that must match the size of
the label 100, and must be adjusted to properly register with the
label area and not cause edge bleeding of the adhesive 120. A
typical change over time for such a process is up to eight hours.
There is no need for special application feet and registration with
the current invention. In example embodiments of the present
invention, the change over time can range from, for example,
approximately one hour to approximately two hours. Accordingly,
change over time is greatly reduced as a result of the present
invention.
[0108] FIG. 3 shows an exemplary embodiment of a system 230 where a
stack of precut activatable labels 150 are activated and affixed to
items, e.g., containers 160. Each of the labels 100 are picked up
by an actuator, for example, a conveyor belt 240, such that the
adhesive layer 120 is in contact with the conveyor belt, and each
of the labels is transported past a printer 250, which prints
indicia 130 onto the face of the label. In example embodiments, the
printer is configured to print images digitally, for example, using
a thermal or other type of printer. The conveyor belt then
transfers the label to another actuator, for example, a vacuum drum
180, such that the adhesive layer is not in contact with the drum,
and the drum transports the labels past a NIR source 200, which
activates the labels, in particular, the labels' adhesive. The
activated labels are then transported to the items where they are
affixed to the items.
[0109] FIG. 3A shows an exemplary embodiment of a system 141 for a
Print and Apply (P&A) type of label applicators, where a
continuous roll of labels 151 is provided to the Print and Apply
machine. The web of labels is moved on a line 152 to a printer 251
where each label is printed by indicia 130 before it is cut by a
cutter 252. The printed and cut labels are then transferred in the
activation area using a conveyor, a vacuum belt 101 or similar
component, past a NIR Short Wave IR (SWIR) or MWIR source 201 which
activates each label in a fraction of a second. The activated label
is then transported to the product 161 to which they are affixed. A
belt applicator 181 can be used for transporting and/or applying
labels.
[0110] Test results show that the spectra of IR from both NIR and
MWIR radiations are highly effective at coupling with the
dicyclohexyl phthalate based adhesive 120; other forms of heating
such as microwave, laser, inductive heating, forced air, IR,
visible light energy, radiant heat energy, and UV, are also useful
when used in combination with appropriately matched additives that
absorb in the appropriate frequency ranges. In an example
embodiment, the energy that is used to activate the adhesive has a
peak wavelength from approximately 0.8 micrometer to approximately
3.0 micrometers. In another example embodiment, the energy has a
peak wavelength from approximately 1.25 micrometer to approximately
2.5 micrometers. The energy that is used to activate the adhesive
can be output from a lamp(s) 200. In one example embodiment, the
lamp(s) output energy wavelengths from approximately 0.8 micrometer
to approximately 5 micrometers with a peak wavelength at
approximately 0.8 micrometer. In yet another embodiment, the
lamp(s) are used to output activation energy having wavelengths
from approximately 0.8 micrometer to approximately 5 micrometer
with a peak wavelength at approximately 2.0 micrometer. In yet
another embodiment, the lamp(s) are used to output activation
energy having wavelengths from approximately 0.8 micrometer to
approximately 5 micrometer with a peak wavelength at approximately
1.5-1.6 micrometer.
[0111] FIG. 3B schematically illustrates another preferred
embodiment system 90 for applying a label with an activatable
adhesive to an item such as a container. The system 90 generally
comprises a printer unit designated as A in FIG. 3B, a thermal
activation unit designated as B, and an applicator unit designated
as C. The system also preferably comprises a control system (not
shown) described in greater detail herein. The printer unit A
applies printed text, indicia or other markings onto one or more
labels or label assemblies. The label or label assemblies
preferably carry a layer of pre-activated adhesive. The printer
unit includes a label roll, a print roller, and a print head as
schematically depicted in FIG. 3B. The printer unit may also
comprise one or more ribbon sensors 25 for detecting movement,
position, and/or characteristics of the printing ribbon. The ribbon
sensor(s) 25 ensure that no ribbon is transported into the thermal
activation unit B, with the labels.
[0112] The preferred system 90 also comprises a thermal activation
unit B which activates the adhesive layer or regions of adhesive
carried on the label or label assembly transported from the printer
unit A. As label or label assemblies enter the thermal activation
unit B, a cutter 1 cuts or otherwise forms the label or label
assemblies into desired sizes and/or shapes. Cut or sized labels 3
are then transported through the thermal activation unit B by a
transport unit 5 having a transport chain 4, conveyor or other
suitable transport means. The transport chain 4 may be coated or
otherwise receive one or more protective coatings. The transport
chain 4 is configured to allow air flow therethrough and
accommodate a relatively small bending radius. These
characteristics promote a compact design and heat resistance. As
the labels 3 are transported through the thermal activation unit B,
the labels 3 are exposed to near infra red (NIR) radiation, such as
emitted by one or more NIR lamps 10, 11, 12, and 13. The lamps 10,
11, 12, and 13 are preferably part of a lamp unit 19 which includes
cooling units such as a first fan 8 that draws air into the region
of interest, and a second fan 9 that exhausts air therefrom. The
thermal activation unit B preferably includes one or more covers,
the position of which is detected by cover switches such as
switches 23 and 24. Preferably provided proximate the outlet for
heated air exiting the thermal activation unit B, one or more lamp
temperature sensor units 15 are provided. It is also preferred that
one or more sensors be provided in and around the area in which the
labels 3 are activated. For example, a first label sensor 16 is
positioned proximate labels entering the activation area. A second
label sensor 17 is positioned proximate labels exiting the
activation area. These sensors review material of the incoming and
outgoing labels, particularly the material position and
completeness by analyzing the edges of the label. Upon detecting
any differences, the control system will initiate an emergency
stop. The sensors 16 and 17 are particularly suited for detecting a
condition in which labels are burning or otherwise undergoing
degradation. Specifically, the outputs from the sensors 16 and 17
can be compared, as performed by a comparator, and if sufficiently
different from one another, can indicate the existence of a label
degradation condition. For example, labels exiting the transport
unit 5 having edges that were charred or curled would indicate a
problematic and/or hazardous situation. An emergency shutdown
sequence could then be initiated. A temperature sensor 18 may be
used to analyze the temperature of the labels 3 or layers thereof.
Specifically, the temperature sensor(s) 18 are used to control the
activation temperature of the label. The transport unit is
generally noted as 5 and may include infrared (IR) shielding 2 to
prevent damage or exposure to infrared radiation by the fans 6 and
7. Fans 6 and 7 generally serve to exhaust relatively hot air away
from the labels 3 and transport unit 5. The fans 6 and 7 are
preferably located below the transport chain 4, or on an opposite
side from the labels, to thereby assist in holding the label flat
on the transport chain so that the labels do not contact any hot
objects within this region.
[0113] The thermal activation unit B also preferably comprises one
or more quartz glass plates, schematically depicted in FIG. 3B as
item 14. The quartz glass plates 14 are positioned between the
labels 3 and the lamps or emitters. The quartz glass plates 14
prevent contact from occurring between the emitters and the labels.
In one embodiment, the area or region around the quartz glass
plate(s) is enclosed and one or more large displacement or high
speed fans are used to withdraw relatively hot air from the
enclosed area. The hot air surrounding the emitters is thereby
prevented from reaching or contacting the labels. The use of one or
more quartz glass plates significantly increases the safety and
dramatically reduces the potential for fire hazards resulting from
labels igniting or burning. The use of the quartz glass plate(s)
also serves to allow only particular wavelengths of light to pass
through the plates and thereby reach the labels. Thus, the labels
are only heated by a portion of the spectrum of radiation from the
emitters.
[0114] FIG. 23 illustrates average maximum temperatures reached at
various dwell times using emitters at 90% power and 100% power in
two different arrangements. The emitters used were Fast Response
Midwave IR Emitters from Heraeus Noblelight GmbH of Germany. In one
arrangement, quartz glass plates are positioned between the
emitters and the labels. In another arrangement, quartz glass
plates are not used, and so the labels are fully exposed to the
emitted radiation. The quartz members absorbed a portion of the
emitter's energy thereby reducing the overall energy absorption by
the label, as indicated by the somewhat lower temperatures. The
quartz members are believed to block or otherwise hinder
transmission of radiation from the emitters having wavelengths
longer than 3.5 .mu.m.
[0115] Referring to FIG. 3B again, after the labels 3 have been
activated, they are transported to an applicator unit generally
denoted as C in FIG. 3B. The applicator unit or transport
applicator 26 applies the activated labels 3 onto the items of
interest. One or more sensors such as sensor label progress sensors
20 and 21, and a sensor label stop position 22, are preferably used
to control material transport. The number of sensors used generally
depends upon the label size and shape. A movement sensor 28 may
also be used to detect movement within the applicator unit C.
[0116] The system 90 may include additional sensors and control
provisions. For example, the system 90 may include one or more
signal interfaces between any of components A, B, and C. A
Universal Signal Interface 27 is illustrated between components A
and B. A start sensor or foot switch 29 can be used in conjunction
with any of the components. The system 90 can include a
programmable logic controller (PLC) or other control system as
known in the art.
[0117] FIG. 3C shows an exemplary embodiment of a system 790 using
digital printing and laser cutting. System 790 is referred to
herein as a Prime, Print & Apply System, where a continuous
roll of labels is provided to the system. The system 790 generally
parallels previously described system 90 of FIG. 3B and includes a
printer unit A, a thermal activation unit B, and an applicator unit
C. However, instead of a cutter 1 used in the system 90, a laser
cutter la is used. And, instead of a print head and ribbon assembly
as used in the system 90 shown in FIG. 3B, the system 790
preferably utilizes a digital printer. The remaining components in
the system 790 are as previously described in conjunction with the
system 90 of FIG. 3B. Generally, a web of labels is moved on a line
to a digital printer where each label is printed to form indicia or
other markings before the label is cut by a laser to a predefined
shape. The label matrix is then separated from one or more
substrate layer(s) kept in place on a vacuum belt or alike. The
label matrix is driven to another direction and rewinds around a
roller. The printed and cut labels are then transferred in the
thermal activation area B using a conveyor, a vacuum belt or
similar component, past a SWIR or MWIR source which activates each
label in a fraction of second. The activated label is then
transported to the product to which they are affixed in the
applicator unit C. A belt applicator can be used for transporting
and/or applying labels.
[0118] FIG. 3D shows an exemplary embodiment of a system 890 using
digital printing and laser cutting. This system is also referred to
as a Prime, Print & Apply System, where a continuous roll of
labels is provided. The system 890 generally parallels the system
790 however uses a laser cutter lb that is located further
downstream, in the applicator unit C shown in FIG. 3D. In contrast
and as previously described in conjunction with FIG. 3C, the laser
cutter la is located between the printer unit A and the thermal
activation unit B, and particularly, within the thermal activation
unit B. In system 890, the web of labels is moved on a line to a
digital printer where each label is printed to form indicia or
other markings. The web of printed labels is then transferred in
the thermal activation area B past a SWIR or MWIR source which
activates each printed label in a fraction of second. The activated
web of printed labels is then transferred to the applicator unit C
where the web or plurality of labels is cut into a predetermined
label shape by a laser while on a vacuum belt or alike. The label
matrix is separated from the individual label which is kept in
place on a vacuum belt or alike and winds up around a roller. The
cut and activated label is then transported to a product to which
they are affixed.
[0119] In another variant of the previously noted embodiments, the
printer and laser cutting systems may also be placed after or
downstream of the activation of the web. The prime printer prints
indicia or other markings on the web of activated adhesive which is
then cut in label shape using a laser while on a vacuum belt or
alike. The label matrix is separated from the individual label
which is kept in place on a vacuum belt or alike and winds up
around a roller. The cut and activated label is then transported to
the product to which they are affixed.
[0120] In yet another embodiment, the web of activatable linerless
is pre-perforated to the shape of the labels. The web will follow
the same path as in FIG. 3D but instead of laser cutting the
activated labels, the web passes over a sharp edge that separates
the leading edge of the label from the matrix. The label is then
placed in contact with a receiving substrate, adhering to the
substrate, upon which the matrix is separated therefrom.
[0121] FIG. 4 shows an exemplary method of applying a label 100
with an activatable adhesive 120 to an item 160. The method starts
at step 260, and then, at step 270, a plurality of labels with a
layer of activatable adhesive are provided. At step 280, a
plurality of items with a second surface are provided, and at step
290, a source of energy 200 is provided. At step 300, the adhesive
on the labels is exposed to radiation to render a tacky surface on
the adhesive. At step 310, the label is applied to the item at a
rate of approximately 500 labels per minute. The method ends at
step 320.
[0122] FIG. 5 shows an exemplary method of activating a label 100.
The method starts at step 330, and then, at step 340, the label
with a layer of activatable adhesive 120, as defined in Table 1, is
provided. At step 350, a source of energy 200 is provided, and, at
step 360, the adhesive on the label is exposed to radiation so that
the adhesive becomes tacky. The method ends at step 370.
[0123] FIG. 6 shows an exemplary method of applying a label 100
with an activatable adhesive 120 to an item 160. The method starts
at step 380, and then, at step 390, a plurality of labels with a
layer of activatable adhesive are provided. At step 400, a
plurality of items with a second surface is provided, and, at step
410, a printer 250 is provided. At step 420, the facestock 110 of
the label is printed. At step 430, a source of energy 200 is
provided. At step 440, the adhesive on the labels is exposed to
radiation to render a tacky surface on the adhesive. At step 450,
the label is applied to the item at a rate of approximately 500
labels per minute. The method ends at step 460.
[0124] FIG. 6A shows an exemplary method of applying a label such
as label 100 depicted in FIG. 1 with an activatable adhesive 120 to
an item such as a container 160 depicted in FIG. 2. The method
starts at step 381, and then, at step 391, a roll of labels with a
layer of activatable adhesive are provided. At step 401, a
plurality of items with a second surface is provided, and, at step
411, a printer 251 is provided. Preferably, the printer is a
digital printer. At step 421, the facestock 110 of the label is
printed. At step 431 a cutter is provided. Preferably, the cutter
is a laser cutting system. At step 441 the label is cut to a
pre-set length. After cutting, an optional operation (not shown)
may be performed in which the label matrix is separated and wound
up. At step 451 a source of energy 200 (FIG. 2) is provided. At
step 461, the adhesive on the labels is exposed to radiation to
render a tacky surface on the adhesive. At step 462, the label is
applied to the item, such as the container 160 in FIG. 2, at a rate
in excess of 60 labels per minute. The method ends at step 463.
[0125] FIG. 6B illustrates another exemplary method of applying a
label to an item such as a container. Upon initiating a start 1000,
an operation 1005 of providing a roll of activatable adhesive
labels is performed. In operation 1010, a plurality of items such
as containers to receive the labels are provided. In operation
1015, a printer and preferably a digital printer is provided. The
facestock side of the label is then printed in operation 1020. In
operation 1025, a source of activating energy is provided. In
operation 1030, the adhesive is exposed to direct radiation to
render the surface of the adhesive tacky. A cutting system is
provided in operation 1035. In operation 1040, the activated label
is cut to a desired shape. In operation 1045, labels are applied to
the items such as containers, and preferably at a rate of greater
than 60 labels per minute. In operation 1050, the label matrix is
separated and wound up. The end of the process is designated as
operation 1055.
[0126] While the above methods mention an exemplary rate for
applying a label 100 to an item 160 of approximately 500 labels per
minute, the rate can range from greater than approximately 60
labels per minute to upwards of approximately 1,000 labels per
minute. Example rates for applying a label to an item according to
the methods of the present invention include approximately 120
labels per minute, approximately 250 labels per minute, and
approximately 500 labels per minute.
[0127] As previously noted, NIR and Short Wave IR energies are
efficient tools for activating the adhesives 120 in a rapid manner,
but may cause damage to printed labels 100 due to absorption of the
energy by the pigments in the indicia 130 that is printed on the
facestock 110 of the labels. Referring additionally to FIG. 7, to
overcome this issue a reflective layer 470 is introduced into the
construction of another embodiment of a label 480. The reflective
layer is placed between the facestock layer 110 and the adhesive
layer 120. When the adhesive of the adhesive layer is directly
exposed to NIR energy, some of the energy is absorbed as the
radiation passes through the adhesive. The remaining, non-absorbed
energy is reflected by the reflective layer and redirect back
through the adhesive layer causing additional NIR energy to be
adsorbed by the adhesive in the adhesive layer. Hence, not only is
the indicia on the facestock layer protected by overheating, but
the redirection of the radiation by the reflective layer allows for
greater absorption of the energy by the adhesive, thus, requiring
less residence time by the adhesive in the presence of the
radiation to obtain the desired level of exposure to the radiation.
Exposures of the adhesive layer to less than 0.3 seconds of
radiation are possible with these methods using a NIR radiation
source 200, and thus, activation and application rates of greater
than approximately 250 labels per minute can be obtained.
Generally, it is preferred to utilize electromagnetic radiation
emitters to produce the desired radiation at relatively high
intensities.
[0128] Referring to FIG. 7, the reflective layer 470 can be made
with any material that reflects NIR energy. Suitable examples
include gold, silver, aluminum and copper. Aluminum is the one of
the best choices for the reflective layer's material in that
aluminum is inexpensive compared with other suitable metals such as
those previously listed; can easily be applied to the facestock 110
using various metallization techniques, including, for example,
vacuum metallization or coating; and has greater than 95%
reflectivity to NIR energy. The thickness "T" of the reflective
layer can be as small as one micron and still provide suitable
reflectivity, which can be, for example, greater than approximately
90%. It is understood that other reflective layers can be employed
for other suitable radiation sources which would also help to
protect the facestock from discoloration.
[0129] The label's facestock layer 110 can be constructed from any
material that is receptive to the ink that is used to print the
indicia 130 on the facestock layer. Example materials for the
facestock layer include paper, polymer films, metallized paper,
paper backed foil, and metallic foils. Referring additionally to
the example embodiment illustrated in FIG. 8, these facestock
materials can be treated with coatings 490. Examples include clear
top coats, which can further enhance the facestock layer's ability
to receive and retain the ink that is used to print/deposit the
indicia on the facestock layer. Further examples include coatings
that contain a high level of pigment, for example, titanium
dioxide, which can be applied to the facestock layer to increase
the opacity of the label 500.
[0130] Referring additionally to the example embodiment illustrated
in FIG. 9, the reflective layer 470 can include a reflective
pattern 510 that covers partially or in totality the non indicia
bearing surface (also known as "back surface") 520 of the facestock
layer 110. For example, referring additionally to FIG. 10, a
reflective pattern 510 can be placed on the facestock layer so as
to overly indicia 130 on the facestock layer's back surface when
viewed through the label's adhesive layer. This reduces the amount
of reflective material that is needed for the label's
construction.
[0131] Referring additionally to the example embodiment illustrated
in FIG. 11, while the back surface 520 of the facestock layer 110
can be smooth, it is also possible that the back surface of the
facestock layer can be textured. Vacuum metallization of the
textured facestock layer, for example, can yield a textured
reflective surface. Likewise, embossing of a smooth reflective
layer 470 can yield a similar textured reflective surface. Such
textured surfaces can be used to redirect radiation or improve
reflection of radiation from radiation sources that are not
perfectly perpendicular to the plane of the facestock. For example
in FIG. 11, a retroreflective microtexture 530 is shown. U.S. Pat.
No. 6,767,102 to Heenan et al. illustrates examples of various
retroreflective surfaces. A retroreflector is a device or surface
that reflects light back to its source with a minimum scattering of
light. Thus, an electromagnetic wave front is reflected back along
a vector that is parallel to, but opposite in direction from the
wave's source.
[0132] The labels 100, 480, and 500 of the various embodiments of
the invention can have a variety of sizes and shapes. For example,
referring additionally to FIGS. 12 and 13, the width "W" of an
exemplary rectangular label can range from approximately 0.5
centimeters to approximately 30 centimeters, and the length "L" of
the exemplary rectangular label can range from approximately 0.5
centimeters to approximately 30 centimeters. Accordingly, the
overall surface area of exemplary rectangular labels can range from
approximately 0.25 square centimeters to approximately 900 square
centimeters. The exemplary labels according to the invention can
have any shape, for example, the labels can be rectangular, square,
circular, and other shapes including irregular shapes. Examples of
various label shapes are shown in U.S. Pat. Nos. 2,304,787,
2,569,140 and 2,783,172 to Avery Dennison.
[0133] The various labels and label systems described herein may
further comprise one or more barrier coats or layers. Generally, a
barrier coat prevents discoloration of the facestock and print
under a wide array of conditions to which the label may be exposed.
Preferably, the barrier coat prevents discoloration of the
facestock and print upon exposure to temperatures of from about
-20.degree. C. to about 80.degree. C., for times of up to several
months or longer and preferably up to 1 year, and at humidity
levels of from about 10% to 99%. Generally, such barrier coats
comprise polymeric materials compatible with the adhesives
described herein and which include an effective concentration of
styrene moieties. In certain embodiments, the adhesive layer and
the barrier layer can be coated with one pass using dual die
technology.
[0134] In several of the preferred embodiment adhesive
formulations, dicyclohexyl phthalate is used as a plasticizer and
has a peak melting temperature at 63.degree. C. Once the adhesive
is activated by radiation or other energy source, the plasticizer
stays in liquid form and may migrate from the adhesive layer to its
contact area. The higher the temperature, the faster the migration.
Thus, the barrier layer covers the adhesive side of a label, seals
capillaries of facestock and serves as a barrier to minimize
plasticizer migration from the adhesive side to the print side of
the label.
[0135] Poly(vinyl alcohol) is a very commonly used material for an
oxygen permeability barrier and dye migration barrier. However
label construction with this poly(vinyl alcohol) layer produces a
lower tack than that without this layer. From a compatibility point
of view, a polymer material bearing styrene units should be more
compatible. A mixture of one to one weight ratio of HYCAR 26288 and
HYCAR 26315, both available from Lubrizol Corp. of Cleveland, Ohio,
is an example of a preferred formulation for use as a barrier
coating or layer. Both polymers include styrene moiety in their
molecular backbone. The coat weight of the barrier layer also
impacts the adhesive performance as well, since plasticizer will be
absorbed by the barrier layer. Since plasticizer is "consumed" by
the barrier layer, the higher the barrier layer coat weight, the
lower the adhesive tack. The preferred barrier layer coat weight is
below 12 g/m.sup.2 (gsm). The most preferred coat weight is in
between 2 to 10 g/m.sup.2 (gsm). The barrier layer is preferably
used to cover the adhesive side of the label and to seal
capillaries of the facestock. For this reason, polymeric substances
having glass transition temperatures less than 80.degree. C. are
preferred. The most preferred glass transition temperature is lower
than 60.degree. C.
[0136] The present invention adhesives can be used in a wide range
of layered arrays. Generally, such arrays include a substrate, one
or more functional layers such as reflective layers and/or barrier
layers, and one or more layers of the adhesive, which is preferably
in the form for use as a linerless adhesive. FIG. 14 schematically
illustrates a layered assembly 600 comprising a layer 610 of a
linerless adhesive, a substrate 630, and a barrier layer 620
disposed between the adhesive layer 610 and the substrate 630. The
substrate is preferably a paper facestock or a transparent film
substrate such as PET and BOPP, etc. As illustrated in FIG. 14, the
barrier material, which also functions as a binder layer, is coated
on the substrate 630, followed by coating the adhesive 610 on the
barrier layer 620 by direct coating techniques. The barrier layer
620 can be coated on the film substrate 630 by either direct coat
or transfer coat techniques. In general, such adhesives include
materials that have relatively low melting points such as in the
range of 50.degree. C. to 120.degree. C., which includes organic
materials such as plasticizers, tackifiers, and combinations. The
inclusion of such relatively low melting point materials in the
adhesives imparts a resulting activation temperature of such
adhesive within this range of temperatures. Upon heating, the
molecules of the solid plasticizer, and/or tackifier will be
absorbed and interact with the adhesive base polymer at a molecular
level to provide an either permanent or removable pressure
sensitive paper or film label construction.
[0137] Additionally, the barrier layer can enhance the anchorage of
the adhesive with a wider drying temperature range during adhesive
coating process. In addition, the barrier layer also serves as a
guard to minimize bleeding of plasticizer from the adhesive side to
the facestock. Furthermore, the barrier layer can have a thickness
of less than 12 microns and have a glass transition temperature
lower than 80.degree. C.
[0138] Referring to FIG. 14, the barrier layer 620 can be a
polymeric material having a glass transition temperature less than
80.degree. C. and with a thickness less than 12 microns. The primer
layer can be applied by traditional coating methods, such as knife
coating, roll coating, and die coating.
[0139] In certain embodiments, and as described herein, carbon
black or other like agent(s), are incorporated into one or more
layers of a label assembly to promote activation of the adhesive.
Generally, the incorporation of carbon black reduces energy
consumption for the activation process. Reduced energy consumption
may be exhibited or result in cost savings, higher processing
speeds, and/or further promote "green" aspects of the technology.
Moreover, incorporating carbon black in one or more layers or a
label assembly enables isolation of lamps or other radiation
emitters for adhesive activation. Additionally, incorporating
carbon black in one or more layers of a label assembly enables the
distance between the lamps or radiation emitters, and the labels to
be increased, thereby further promoting safety of the system.
[0140] The carbon black or other alternate mediums, when
incorporated into a label or label assembly promote energy
absorption of the material, thereby leading to improved
efficiencies. The carbon black can be incorporated into any layer
of a label assembly. However, it is generally preferred that the
carbon black be incorporated within the adhesive layer. However,
the invention is not limited to such and includes the incorporation
of carbon black in other layers in addition to or instead of the
adhesive layer. For example, carbon black can be incorporated in a
barrier layer. It is also contemplated that carbon black or other
like agent(s) can be incorporated in a primer layer. If carbon
black is used in a primer or barrier layer, it can be used at the
previously noted concentrations as when incorporated in an adhesive
layer. However, for many applications, it is preferred to use
carbon black at higher concentrations such as about 0.1%.
[0141] It is noted that other agents can be used instead of or in
addition to carbon black for promoting energy absorption.
Non-limiting examples of such other agents include various organic
dyes, coloring agents, and pigments; and various inorganic dyes,
coloring agents, and pigments. It will be understood that a wide
array of inks or other agents could be used. Moreover, combinations
of any of these can be used. It is contemplated that combinations
of agents can be incorporated in multiple or different layers of a
label assembly. For example, carbon black can be incorporated into
an adhesive layer and one or more organic and/or inorganic dyes can
be incorporated in a barrier layer.
[0142] The concentration of the carbon black or other like agent(s)
in the layer of interest can vary, so long as the concentration
beneficially promotes energy absorption into that layer and an
increase in temperature. For example, when incorporating carbon
black into an adhesive or barrier layer, generally the
concentration is at least about 0.1%, and preferably at least about
1%. The upper limit depends on numerous factors.
Systems
[0143] The present invention also provides various systems using
the activatable adhesives, and layered arrays and/or label
assemblies described herein. In one preferred aspect, a system for
applying printed labels to an article comprises an activatable
label including a layer of selectively activatable adhesive that
exhibits an activation time of less than 1 second, and an apparatus
configured to apply the label to an article. The apparatus includes
an energy source that is configured to emit energy, and one or more
actuators that are configured to (i) receive the activatable label,
(ii) transport the activatable label through the emitted energy,
and (iii) transport the activatable label to a position at which
the activatable label is applied to the article. The activatable
adhesive preferably exhibits the characteristics noted herein
associated with the preferred adhesives such as an activation time
of less than 1 second, more preferably less than 0.5 seconds, and
most preferably of about 0.3 seconds or less. The adhesives also
preferably exhibit an open time of from about 0.1 seconds to about
72 hours, and more preferably of from about 10 seconds to 60
seconds. The adhesives used in these systems also exhibit certain
preferred initial tack properties as described herein.
[0144] Another preferred embodiment system comprises an activatable
label including a layer of selectively activatable adhesive that
upon activation, exhibits an open time of at least 72 hours, and an
apparatus configured to apply the label to an article. The
apparatus includes an energy source that is configured to emit
energy, and one or more actuators that are configured to (i)
receive the activatable label, (ii) transport the activatable label
through the emitted energy, and (iii) transport the activatable
label to a position at which the activatable label is applied to
the article. As previously noted, the adhesives used in this system
preferably exhibit the previously noted activation times, and
initial tack values.
Uses
[0145] The adhesives described herein can be used in a wide array
of applications. A preferred use is in layered arrays such as label
assemblies.
[0146] The various layered arrays and label assemblies can be used
in numerous applications such as for example, receiving printed
indicia, information, designs, and the like. A particularly
preferred use for label assemblies as described herein is use in
printers.
EXAMPLES
[0147] Exemplary procedures for preparing the base polymer noted in
Table 2, are as follows:
Example 1
[0148] An emulsion adhesive polymer base is prepared by emulsion
polymerization from a plurality of monomers consisting of 37.2%
butyl acrylate (BA), 29.3% styrene, 29.3% methyl methacrylate
(MMA), 1.7% methacrylic acid (MAA), and 2.5% acrylic acid (AA),
based on the weight of all monomers, with 0.06% by weight of
n-dodecy mercaptan added as a chain transfer agent. A one-liter,
jacketed, cylindrical reaction flask equipped with a four-neck
flask head was fitted with a steel stirring rod with multiple steel
blades, a reflux condenser, a thermometer, and a nitrogen inlet
tube. The stirring speed is set at approximately 126 rpm, and the
reaction temperature was set at 80.degree. C. A reactor pre-charged
solution is made by dissolving 1.0 g of HITENOL BC-10 (97% solids,
manufactured by Dai-lchi Kogyo Seiyaku Co., Ltd. of Kyoto, Japan)
surfactant in 100 g deionized ("DI") water. A pre-emulsion feed
soap solution is formed by dissolving 2.0 g HITENOL BC-10 and 105 g
DI water. A monomer mix is made up with 140 g of n-butyl acrylate,
110 g styrene, 110 g of methyl methacrylate, 6.5 g of methacrylic
acid, 9.1 g of acrylic acid, and 0.24 g of n-dodecyl mercaptan. The
monomer mix is added to the pre-emulsion solution under stirring
for 10 min. An initiator solution A is prepared by dissolving 0.75
g potassium persulfate ("KPS") in 67 g of DI water; solution B is
made by dissolving 0.5 g of KPS in 67g of DI water. A kickoff
initiator solution is prepared by dissolving 0.75 g of KPS in 38 g
of water. The reactor pre-charged solution is introduced to the
glass reactor, which has been flushed with nitrogen. The kickoff
initiator solution is added when the solution temperature reached
80.degree. C. After 5 minutes, 20 g of the pre-emulsion solution
was introduced into the reactor. Upon observing polymerization, the
pre-emulsion solution and initiator solution A feeds are started.
Initiator solution B is fed at the end of solution A. The
pre-emulsion solution feed is completed in a 4 hour period, and the
initiator solution A and B feeds are completed in 4 hours and 15
minutes. Polymerization continues for another 30 minutes after
completion of the initiator solution B feed. The polymerization
temperature is maintained at 80.degree. C. during the
polymerization. Polymerization of the monomer mixture yields a
polymer latex, which can be formulated further for linerless
adhesives, and which can be coated on the desired substrates.
Example 2
[0149] The same polymerization procedure that is used in Example 1
is used, except that the monomers used for the polymerization are
used in the following weight percentages. 48.0% BA, 23.9% styrene,
23.9% MMA, 1.7% MAA, and 2.5% AA.
[0150] Preparation of an exemplary white heat-activated adhesive is
as follows. A switchable adhesive formulation is prepared from the
noted adhesive polymer base by blending with a selected plasticizer
and tackifier at room temperature for enough time to ensure a
homogenous composition. Typically, the preferred melting point of
such solid plasticizer is above 40.degree. C. In this example,
ground plasticizer dicyclohexyl phthalate or U250M supplied by
Unitex Corp. of Greensboro, N.C. is used. The melting point of
U250M is in the range of 63.degree. C. to 65.degree. C. The
exemplary tackifier is TACOLYN 3400 (softening point 92.degree. C.)
which is a resin dispersion by Eastman Chemical Company of
Kingsport, Tenn. TACOLYN 3400 is a resin ester dispersion. More
specifically, TACOLYN 3400 is an aqueous, 55% solids, solvent-free
anionic rosin ester dispersion prepared from a highly hydrogenated,
high softening point resin. Not to be held to any particular
theory, it is believed that when the adhesive is irradiated, the
selected plasticizer is melted. The small plasticizer molecules are
able to slip in between the adhesive base polymer chains to
function as a "lubricant", even after the polymer cools. As a
result, the free volume of the polymer is increased, or the glass
transition temperature (T.sub.g) of the adhesive polymer base is
lowered, which leads to highly flexible adhesive coating.
Advantageously, in certain exemplary embodiments, the adhesive does
not include carbon black, graphite, ink(s), dye(s), pigment(s),
and/or colorant(s). However, other exemplary embodiments of the
adhesive include the use of such agents.
Example 3
[0151] An acrylic emulsion based polymer particularly adapted for
linerless heat-activatable adhesives was prepared as follows.
Referring to Table 4 below, a reactor charge is made by dissolving
18.2 g HITENOL BC-10 surfactant (97% solids), 18.2 g POLYSTEP B-19
surfactant available from Stepan of Northfield, Ill. (sodium lauryl
ether sulfate, 32.5% solids), and 1.1 g DREWPLUS L-198 foam control
agent available from Ashland Aqualon of Ashland, Inc. of Lexington,
Ky, in 19.376 kg of deionized ("DI") water. This is summarized as
reactor charge (A) in Table 4. As described later herein, 90.8 g of
potassium persulfate ("K-persulfate") is subsequently added to this
charge prior to pre-emulsion feed.
TABLE-US-00005 TABLE 4 Exemplary Reactor Charge Parts by Weight g
Lbs A) Reactor Charge: Di-water 19,376 42.718 POLYSTEP B-19
(32.50%) 18.20 0.04 HITENOL BC-10 (97.0%) 18.20 0.04 DREWPLUS L-198
(100.0%) 1.10 0.002 Kick-off K-persulfate 90.80 0.20 Total
19,504.30 43.00 B) Soap Solution: Di-water 14,455 31.868 POLYSTEP
B-19 (32.50%) 853.52 1.88 AEROSOL OT-75 (75.0%) 227.00 0.50 HITENOL
BC-10 (97.0%) 472.20 1.04 DREWPLUS L-198 (100.0%) 1.10 0.002 Total
16,008.80 35.29 C) Monomer Mix: BA 5248 11.57 EA -- -- Styrene
31,919 70.37 MMA 1333 2.94 MAA 508.48 1.12 AA 708.24 1.56 EGDMA
621.98 1.37 n-DDM 771.80 1.70 Total 41,110.50 90.63 D) Catalyst
Solution for Delay Addition: Di-water 4213 9.29 K-persulfate 108.96
0.24 Total 4321.96 9.53 E) Rinse Di-water 227.00 0.50 F) 19%
Ammonia Solution: 272.40 0.60 G) DREWPLUS L-198 18.20 0.04 H)
ACTICIDE GA (1.50%) 4.54 0.01 I) Di-water 227.00 0.40 Batch Total
81,694.7 180.00 Surfactants: 2.248 pphm K-persulfate: 0.481
pphm
[0152] The reactor charge was then introduced into a reactor and
heated to 78.degree. C. The reactor contents are preferably
agitated.
[0153] A soap solution is formed for pre-emulsion as follows.
853.52 g of POLYSTEP B19, 227 g of AEROSOL OT-75 surfactant
available from Cytec Industries, Inc. of West Paterson, N.J.
(sodium dioctyl sulfosuccinate), 472.2 g of HITENOL BC-10, and 1.1
g DREWPLUS L-198 were added to 14.455 kg of deionized water. This
is summarized as soap solution (B) in Table 4.
[0154] A monomer mix is formed by combining 5248 g BA, 31.919 kg
styrene, 1333 g MMA, 508.48 g MAA, 708.24 g AA, 621.98 g EGDMA, and
771.8 g n-DDM. This is summarized as monomer mix (C) in Table 4.
Expressed as a weight percentage based upon the adhesive polymer
base, the concentrations of these monomers are 12.8% BA, 77.6%
styrene, 3.2% MMA, 1.2% MAA, and 1.7% AA, 1.5% EGDMA, and 1.9%
n-DDM.
[0155] The monomer mix (C) is added to the soap solution (B) while
agitating to form a stable monomer mix (B+C) pre-emulsion.
Preferably, the mix (B+C) is subjected to slow agitation while
feeding as described below in Table 5.
TABLE-US-00006 TABLE 5 Details of Pre-Emulsion Mix Amount Time Rate
Delay Addition: Lbs Minute Lbs (g)/min. Pre-emulsion (B + C) (1)
125.92 200.00 0.63 (285.8 g) Pre-emulsion (B + C) (2) -- -- --
Catalyst Solution (D) 9.53 200.00 0.048 (21.8 g)
[0156] A catalyst solution for delay addition is formed by adding
108.96 g potassium persulfate to 4213 g deionized water.
[0157] At a reactor contents temperature of 78.degree. C., the 90.8
g of potassium persulfate are added. The reactor contents are
purged with nitrogen for 2 minutes. After the noted 2 minutes, the
nitrogen purge is discontinued and a first portion of the
pre-emulsion (B+C) is fed to the reactor and introduced to the
reactor charge (A).
[0158] The pre-emulsion (B+C) is fed to the reactor for 30 minutes.
After 30 minutes, a catalyst solution (D) is then administered to
the reactor. As summarized in Table 4 under (D), the catalyst
solution includes 108.96 g of potassium persulfate in 4213 g
deionized water.
[0159] After administering the catalyst solution (D) to the
reactor, the reactor batch temperature is increased and maintained
at 86.+-.3.degree. C. The batch is agitated as needed.
[0160] Upon addition of the pre-emulsion (B+C), one half of an
additional amount of deionized water in an amount of 113.5 g is
used to rinse the tank previously retaining the pre-emulsion (B+C)
and that portion of rinse water is then added to the reactor.
[0161] After the catalyst solution (D) has been fully administered
to the reactor, the batch is maintained at a temperature of from
about 82.degree. C. to about 85.degree. C. for 20 minutes.
[0162] After expiration of the noted 20 minute period,
concentration of residual monomers in the batch is measured. Once
the concentration of residual monomers is less than 0.05%, cooling
of the batch to 35.degree. C. is initiated. If the concentration of
residual monomers is not less than 0.05%, the batch temperature of
82.degree. C. to 85.degree. C. is held for an additional 30 minutes
and then allowed to cool to 35.degree. C.
[0163] As the temperature of the batch cools, a 19% ammonia
solution (F) in Table 4, is slowly added beginning once the
temperature reaches 70.degree. C. Specifically, 272.4 g of 19%
aqueous ammonia solution are added. After addition of the ammonia
solution, another amount of DREWPLUS L-198 is added. This is
designated as (G) in Table 4 and constitutes 18.2 g of
DREWPLUS.
[0164] Once the temperature of the batch reaches 35.degree. C.,
4.54 g of ACTICIDE GA, an industrial microbiocide available from
Acti-Chem Specialties of Trumbull, Conn. is added. This is shown as
(H) in Table 4.
[0165] Additional amounts of deionized water can be added to adjust
for desired solids content and viscosity. For example, as noted in
Table 4 as (I), 227 g of deionized water is added to the resulting
product.
[0166] Additional processing operations can be performed such as
filtering. An example of a representative filtering operation is
filtering the product through a 25 micron or 50 micron filter.
[0167] Table 6 summarizes representative specifications for the
resulting emulsion based polymer product. The resulting dry base
polymer has a weight average molecular weight of 23,000 Daltons and
a glass transition temperature of 76.degree. C.
TABLE-US-00007 TABLE 6 Emulsion Based Polymer Product
Specifications: pH: 6.0-7.0 Total Solids: 53.0 .+-. 0.5% Grits:
<50 ppm. on 50 micron filter Reactor Fouling: very slight
Viscosity: 1,000-3,500 Cps., #3 Spindle/30 rpm/25.degree. C./LVT
Residual monomers: <0.05%
Example 4
[0168] An emulsion-based adhesive system was prepared by using the
acrylic emulsion based polymer formed in Example 3. Specifically,
the adhesive system was formed as set forth in Table 7.
TABLE-US-00008 TABLE 7 Exemplary Adhesive System Component Parts by
Dry Weight Polymer of Example 3 (Adhesive Polymer Base) 25.00
UNIPLEX 250 dispersion (Plasticizer) 66.00 ARAKAWA SE-E 650
dispersion (Tackifier) 9.00 Total 100.00
[0169] Specifically, the adhesive system is prepared by combining
25 parts by weight of the polymer produced in Example 3 with 66
parts by weight of UNIPLEX 250 dispersion and 9 parts by weight of
ARAKAWA SE-E 650 dispersion available from Arakawa Chemical of
Osaka, Japan. The UNIPLEX 250 dispersion was prepared by milling
UNIPLEX 250, water, dispersant and defoamer, and serves as a
plasticizer. And, the ARAKAWA component serves as a tackifier.
[0170] This emulsion based adhesive is stable, can be directly
coated onto papers or films and dried in an air-circulated oven up
to 56.degree. C. for 15 minutes without any sign of activation. The
dried adhesive shows very good anchorage to primed or unprimed
papers and film and passes blocking test at 45.degree. C. under 30
psi pressure (about 206,842 Newton/m.sup.2).
[0171] This type of adhesive exhibits excellent tack and good
adhesion to non-polar surfaces and cardboards as well as remains
very tacky greater than 48 hours and clear for a long period of
time after activation under one or more IR lamps for 5 to 10
seconds.
Example 5
[0172] In this investigation, various formulations of heat or
inherently near to mid IR (MWIR) activatable switchable adhesives
were investigated. A set of switchable adhesive formulations were
prepared from the polymers previously described in Example 2 using
base emulsion polymers by blending with a selected plasticizer,
however, without the selected tackifiers as illustrated in Table 8,
below. The preferred plasticizers are solid plasticizers, i.e., the
materials are in a solid state below the application temperature.
Typically, the preferred melting point of such solid plasticizer is
above 40.degree. C. In the following adhesive examples, a ground
plasticizer U250M from UNIPLEX 250 which is supplied by Unitex
Corp. is used. The melting point of U250M is in the range of
63.degree. C. to 65.degree. C. When NIR to MWIR radiation is used
to irradiate the adhesive, the selected plasticizer is melted. As
noted, it is believed that the relatively small plasticizer
molecules are able to slip in between the base polymer chains to
function as a "lubricant", even after the polymer cools. As a
result, the free volume of the polymer is increased, or the glass
transition temperature of the base polymer is lowered, which leads
to a highly flexible adhesive coating, and the G' or G'' can be
lowered to satisfy the Dalquist's criteria (the G' at room
temperature is approximately 5.times.10.sup.5 to 2.times.10.sup.6
dyne/cm.sup.2) for a linerless label application, such as for the
preferred embodiments of the present invention. Details as to
Dalquist's criteria are provided after the description of the
examples herein. In addition, in the adhesive formulations of
Example 5, noted amounts of water and a surfactant available under
the designation IGEPAL CO-887 were included. The water/IGEPAL
CO-887 mixture was prepared by combining 9 parts of water and 1
part of IGEPAL CO-887. IGEPAL CO-887 is a nonylphenoxy
poly(ethyleneoxy) ethanol from Rhodia of New Brunswick, N.J.
TABLE-US-00009 TABLE 8 Compositions of Adhesive Example 5a-5d
Composition Weight (g) (wt % on dry) Base Water/IGEPAL Base Example
polymer U250M CO-887 Polymer U250M 5a 40 20 20 50 50 5b 40 28 20
41.67 58.33 5c 40 36 20 35.71 64.29 5d 40 44 20 31.25 68.75
[0173] Thermal analysis was then performed on the resulting
adhesives to determine the effect of the selected plasticizer on
the rheology behavior of the formulated adhesives.
[0174] The adhesive samples of Examples 5a-5d are inherently NIR to
MWIR radiation activatable. Within up to at least ten minutes,
non-reversible tack was developed when the samples were subjected
to NIR to MWIR irradiation, though, a conventional heat source can
also be applied to activate the adhesive at an elevated
temperature. Adhesion tests using the sample 5a were performed on
different substrates, and the results are listed below in Table 9.
Details as to procedures and practices for measuring adhesive
characteristics such as via 90.degree. peel tests, tack
measurements, and failure mode determinations are set forth herein
after description of the examples.
TABLE-US-00010 TABLE 9 90.degree. Peel Test of Example 5a (Newton/
Sub- Sam- Dwell Coatweight in) (lbf/in) Failure strate ple Time
(g/m.sup.2) Average Average Mode glass 5a 20 min 26.0 5.492 1.235
Slight stain stainless 5a 20 min 26.0 6.399 1.439 Slight steel
stain cardboard 5a 20 min 26.0 2.359 0.530 Clean
[0175] The effect of selected tackifier in the preferred embodiment
adhesives is further demonstrated in the following examples
involving samples Example 5e and Example 5f.
[0176] Adhesive compositions of Examples 5e and 5f are shown in
Table 10, and the effect of the selected TACOLYN 3400 tackifier
(having a softening point of 92.degree. C.), a resin dispersion by
Eastman Chemical, on the switchable adhesive adhesion performance
is illustrated in Table 11. Example 5f shows a dramatic increase in
adhesion on all substrates, and paper failure mode is achieved
within a short dwell time. A preferred application and use of the
preferred embodiment switchable adhesives is in label applications,
which generally require that the activated adhesive has PSA
properties for lamination. FIG. 15 demonstrates that a preferred
embodiment adhesive has good adhesive open time after MWIR
activation to meet such needs for the label lamination. As
demonstrated in Table 11, the preferred embodiment switchable
adhesives are inherently NIR to MWIR radiation activatable, and
they have good adhesion on a broad range of substrates including
high as well as low surface energy surfaces.
TABLE-US-00011 TABLE 10 Compositions of Switchable Adhesive Example
5e and 5f Base TACOLYN Water/IGEPAL Base TACOLYN Polymer U250M 3400
CO-887 Polymer U250M 3400 Example (g) (g) (g) (g) (%) (%) (%) 5e 80
80 0 40 33.33 66.67 0 5f 80 80 80 40 24.39 48.78 26.83
TABLE-US-00012 TABLE 11 90.degree. Peel Test of Switchable Adhesive
Examples 5e and 5f with NIR Activation 90.degree. Peel Test @ 12
ipm Coatweight (Newton/in) (lbf/in) Substrate Sample Dwell Time
(g/m.sup.2) Average Average Failure Mode Glass 5e 20 min 26.0 5.492
1.235 Slight stain 5e 1 hour 26.0 6.852 1.540 Slight stain 5e 5
hours 26.0 6.644 1.494 Slight stain; some paper tear 5e 24 hours
26.0 8.016 1.802 Paper tear 5e 72 hours 25.0 11.52 2.589 Paper tear
5f 20 min 25.0 13.46 3.026 Paper tear 5f 1 hour 25.0 13.65 3.068
Paper tear 5f 5 hours 25.0 12.58 2.829 Paper tear 5f 24 hours 25.0
10.69 2.402 Paper tear 5f 72 hours 25.0 14.29 3.213 Paper tear
Stainless 5e 20 min 26.0 6.399 1.439 Slight stain Steel 5e 1 hour
26.0 7.634 1.716 Slight stain 5e 5 hours 26.0 7.541 1.695 Slight
stain 5e 24 hours 26.0 7.823 1.759 Paper tear 5e 72 hours 26.0
10.41 2.341 Paper tear 5f 20 min 25.0 12.46 2.802 Paper tear 5f 1
hour 25.0 14.61 3.284 Paper tear 5f 5 hours 25.0 13.14 2.954 Paper
tear 5f 24 hours 25.0 7.619 1.713 Paper tear 5f 72 hours 25.0 13.43
3.019 Paper tear Cardboard 5e 20 min 26.0 2.359 0.530 Clean 5e 1
hour 26.0 2.276 0.512 Clean 5e 5 hours 26.0 3.130 0.704 Clean 5e 24
hours 26.0 2.387 0.537 Some fiber tear 5e 72 hours 26.0 6.079 1.367
Paper tear 5f 20 min 25.0 5.404 1.215 CB tear 5f 1 hour 25.0 2.803
0.630 CB tear 5f 5 hours 25.0 3.802 0.855 CB fiber tear 5f 24 hours
25.0 5.615 1.262 CB tear 5f 72 hours 25.0 8.097 1.820 Paper tear
Polypropylene 5e 20 min 33.0 4.662 1.048 Clean 5e 1 hour 33.0 4.745
1.067 Clean 5e 5 hours 33.0 3.152 0.709 Clean 5e 24 hours 33.0
0.237 0.053 Clean 5e 72 hours 33.0 3.568 0.802 Clean 5f 20 min 34.0
13.05 2.933 Paper tear 5f 1 hour 34.0 13.34 2.998 Paper tear 5f 5
hours 34.0 15.52 3.488 Paper tear 5f 24 hours 34.0 14.38 3.233
Paper tear 5f 72 hours 34.0 18.99 3.082 Paper tear
[0177] It was observed that such PSA characteristics exhibited by
samples 5e and 5f can be maintained up to one week (see Table 12),
and longer.
TABLE-US-00013 TABLE 12 Aging Effect on Tack of Activated Adhesive
of Examples 5e and 5f Average Force (Newton) Example 30 min 1 hour
2 hours 3 hours 4 hours 1 day 2 days 3 days 4 days 5 days 1 week 5e
0.98 1.07 0.94 1.09 0.83 0.79 1.55 0.92 0.98 0.96 1.07 5f 1.72 1.39
1.37 1.39 1.52 1.85 1.20 1.96 1.97 1.73 1.86
[0178] In this investigation, a set of samples designated as
Example 5g were formed using a different type of solid
plasticizers. Specifically, a different solid plasticizer, glyceryl
tribenzoate supplied as UNIPLEX 260M by Unitex Corp., is used to
replace the dicyclohexyl phthalate. Table 13 shows the composition
of the adhesive for sample 5g.
TABLE-US-00014 TABLE 13 Adhesive Composition of Example 5g
Materials Parts Base Polymer 20 U260M 20 TACOLYN 3400 20 Water 9
IGEPAL CO-887 1
[0179] The coated adhesive on paper facestock was activated with
NIR, followed by adhesion testing. Table 14 shows the results of
90.degree. peel adhesion tests. The paper tear failure mode was
achieved on all tested substrates. The short term and long term
aging effects on adhesive open time are illustrated in FIG. 16 and
Tables 14 and 15, respectively.
TABLE-US-00015 TABLE 14 90.degree. Peel Test of Switchable Adhesive
Example 5g with NIR Activation Coatweight (Newton/in) (lbf/in)
Substrate Sample Dwell Time (g/m.sup.2) Average Average Failure
Mode 90.degree. Peel Test @ 12 ipm Glass 5g 20 min 24.0 10.20 2.292
Paper tear 5g 1 hour 24.0 10.11 2.273 Paper tear 5g 5 hours 24.0
10.58 2.378 Paper tear 5g 24 hours 24.0 12.18 2.739 Paper tear 5g
72 hours 24.0 12.19 2.740 Paper tear -- Stainless Steel 5g 20 min
24.0 10.78 2.423 Paper tear 5g 1 hour 24.0 10.77 2.422 Paper tear
5g 5 hours 24.0 10.42 2.342 Paper tear 5g 24 hours 24.0 10.44 2.347
Paper tear 5g 72 hours 24.0 12.00 2.698 Paper tear Cardboard 5g 20
min 24.0 1.263 0.284 CB fiber tear 5g 1 hour 24.0 1.394 0.314 CB
fiber tear 5g 5 hours 24.0 1.768 0.397 CB fiber tear 5g 24 hours
24.0 2.701 0.607 CB tear 5g 72 hours 24.0 3.855 0.867 CB tear
Polypropylene 5g 20 min 24.0 7.967 1.791 Paper tear 5g 1 hour 24.0
8.235 1.852 Paper tear 5g 5 hours 24.0 9.068 2.039 Paper tear 5g 24
hours 24.0 9.248 2.079 Paper tear 5g 72 hours 24.0 8.155 1.834
Paper tear
TABLE-US-00016 TABLE 15 Aging Effect on Tack of Activated Adhesive
of Example 5g Average Force (Newton) Example 30 min 1 hour 2 hours
3 hours 4 hours 1 day 2 days 3 days 4 days 5 days 1 week 5g 2.04
1.93 1.82 1.83 1.82 1.75 1.69 1.87 1.82 1.83 1.86
[0180] In another investigation, a set of samples designated as
Example 5h were prepared using a tackifier having a high softening
point. Rosin ester emulsion, available under the designation "SUPER
ESTER" E-650 (softening point 160.degree. C.), is used to replace
the TACOLYN 3400 in example 5f. SUPER ESTER E-650 is a polymerized
rosin ester emulsion available from Arakawa Chemical Ind. of Osaka,
JP. The formulated adhesive was coated on a 60# paper facestock,
then dried at 50.degree. C. for 10 minutes. MidWave IR or other
heating activation is used for adhesive activation. FIG. 17
outlines the 90.degree. peel test of Example 5h with two different
adhesive coat weights.
[0181] In yet another investigation, the effect of coat weight upon
adhesion properties was investigated. A set of samples designated
as Example 5i were prepared as follows. Specifically, NIR to
MidWave IR activatable adhesives were formulated in accordance with
Example 5 in which a combination of anionic and nonanionic
surfactants is used for the base polymer synthesis. The NIR to
MidWave IR activated adhesive was made, and the adhesion test
results of Example 5i adhesive with different adhesive coat weights
on the selected substrates are listed in Table 16.
TABLE-US-00017 TABLE 16 90.degree. Peel Adhesion Test of Example 5i
90.degree. Peel Test @ 12 ipm Coat weight (Newton/in) (lbf/in)
Comments/ Substrate (g/m.sup.2) Average Average Failure Mode Glass
19.2 5.772 1.298 paper tear Stainless Steel 8.290 1.864 paper tear
Polypropylene 6.737 1.515 paper tear Cardboard 1.879 0.423 some CB
fiber tear Glass 25.6 5.109 1.149 paper tear Stainless Steel 6.725
1.512 paper tear Polypropylene 11.370 2.557 paper tear Cardboard
1.708 0.384 some CB fiber tear Glass 31.6 7.908 1.778 paper tear
Stainless Steel 12.152 2.732 paper tear Polypropylene 12.540 2.819
paper tear Cardboard 3.832 0.861 CB tear
Example 6 and Additional Investigations
[0182] Additional investigations were made as follows. A set of
adhesive samples of the previously described adhesive system of
Example 4 were prepared and the effect of dwell time on peel
characteristics was reviewed. This set of samples is designated as
Example 6a. Specifically, adhesive was coated on a paper facestock
(Vellum Challenger HW by Crown Van Gelder N.V. of Velson-Noord, the
Netherlands), and tested on different substrates. The activated
samples were laminated on to the substrate 5 minutes after the
activation (open time five minutes). Table 17 shows the
results.
TABLE-US-00018 TABLE 17 90.degree. Peel Test of Example 6a (5
Minutes Open Time) Coatweight (lbf/in) Substrate Sample Dwell Time
(g/m.sup.2) Average Polypropylene 6a 20 min 25.0 0.938 Stainless
Steel 6a 20 min 25.0 1.007 Cardboard 6a 20 min 25.0 0.406
[0183] The adhesion of the adhesive increases with increasing dwell
time. FIG. 18 illustrates the change of the 90.degree. peel values
of such adhesive on a cardboard substrate with dwell time. This
data clearly shows that the adhesion becomes stronger until paper
tear failure mode occurs.
[0184] In another set of investigations, a set of adhesive samples
designated as sample 6b were prepared to investigate the effect of
the open time of the adhesive. It is desirable for certain label
applications that a pressure sensitive (PS) property will remain
during the label lamination process, particularly, for high speed
automatic label lamination processes. The various preferred
embodiment adhesives exhibit a unique feature in which their
pressure sensitive properties can be maintained for relatively long
time periods once the adhesive is activated. In FIG. 19, a
spherical probe adhesive tester (SPAT) is used for testing the tack
of adhesive of Example 6. This data demonstrates that once the
adhesive is activated, the tack of the adhesive or the PS property
of the adhesive generally remains constant with time. This provides
a benefit of allowing labels to be laminated on to a targeted
substrate without the limit of open time.
[0185] The data presented in FIGS. 15, 16 and 19 obtained by the
noted SPAT test, reveals that certain preferred embodiment
adhesives exhibit initial peak tack values of from about 1.0 to
about 2.0 Newtons, and typically from about 1.25 to about 1.75
Newtons. However, it will be appreciated by those skilled in the
art that the adhesive formulations of the invention can be
specifically tailored to exhibit initial peak tack values less than
these or greater than these values.
[0186] In another set of investigations, the adhesive system
described in Example 4 was used in various peel tests at 5.degree.
C. as follows. Referring to FIG. 20, the adhesive of Example 4
designated as "LA" was applied to cardboard substrate samples and
dwelled for varying time periods at 5.degree. C. Four different
time periods were used--20 minutes, 1 hour, 24 hours, and 72 hours.
The adhesive was then activated, and the samples at 5.degree. C.
were then laminated with vellum or paper layers. The laminated
samples were then subjected to 90.degree. peel tests at 5.degree.
C. using a chambered Instron system. The laminated samples were
compared to similarly treated and laminated samples formed using a
conventional adhesive commercially available from Avery Dennison
Corporation and designated as "CA." As can be seen in FIG. 20, the
samples using the preferred embodiment adhesive noted from Example
4 exhibited generally consistently stronger adhesive
characteristics as compared to the samples using the conventional
adhesive. In addition, the preferred adhesive exhibited predictable
increased adhesive performance with increased dwell times.
[0187] FIG. 21 illustrates results from similar 90.degree. peel
tests of the two sets of samples, however, also illustrates
90.degree. peel tests performed at room temperature (right hand
side). As evident in FIG. 21, the laminated samples using the
preferred adhesive described in Example 4 exhibited consistent and
increasing adhesive characteristics as dwell time increased, at
both 5.degree. C. and at room temperature. These results
demonstrate the applicability and capabilities of the preferred
adhesives for a wide array of different end use applications.
[0188] Further investigations were conducted to review blocking of
coated adhesives. The various preferred embodiment adhesives
exhibit good anti-blocking properties which will meet the
requirements associated with most application processes. The
previously described coated adhesive on paper facestock was tested
under different pressures. Table 18 indicates that no blocking was
observed under the noted conditions.
TABLE-US-00019 TABLE 18 Blocking Test Temperature Pressure
(.degree. C.) (psi) Rating 45 20 Excellent 45 30 Good
[0189] This data demonstrates that certain classes of the preferred
embodiment adhesives exhibit blocking-free properties or
essentially so, under a temperature of 45.degree. C. and a pressure
of from about 20 to about 30 psi (approximately 137,895
Newton/m.sup.2 to 206,842 Newton/m.sup.2). It is contemplated that
these non-blocking properties are also exhibited at relative
humidity (RH) percentages of from 10% to 99%. These anti-blocking
properties provide a significant feature for the adhesives and
enable them to be used in a wide array of applications such as
labeling. More particularly, it is preferred that the adhesives
exhibit these non-blocking properties before activation and most
preferably, concurrently. That is, certain preferred adhesives
exhibit all of these properties, i.e. non-blocking at a temperature
of 45.degree. C., non-blocking at a pressure of from 15 psi to 30
psi, and non-blocking at a relative humidity level from 10% to
90%.
[0190] Clarity of the preferred embodiment adhesives was also
investigated as follows. Surprisingly, a preferred embodiment
adhesive remains clear or in a generally transparent state after
activation, even after heat is removed for months or longer. This
unique feature of the adhesive permits using the adhesive in
applications where a clear or transparent adhesive is needed, such
as in a clear film label or graphic application. A preferred
embodiment adhesive was coated on a PET film at 13 gsm under
standard coating conditions. The dried adhesive appears white or
translucent in color. Upon activating the adhesive with heat, the
adhesive turns clear and exhibits pressure sensitive properties.
Laminating this film label on a transparent substrate such as glass
shows that the adhesive will remain clear. The clarity of the film
substrate is measured with an optical measuring device available
under the designation Haze-Gard Plus by Gardner. Suitable Haze-Gard
Plus instruments are also available from Qualitest USA of
Plantation, FL. This instrument measures light transmittance, haze,
and other properties according to ASTMD1003D1044. Table 19
demonstrates that the haze of the label changes dramatically before
and after the activation. Meanwhile, it is noticed that the haze of
the laminated film label generally continually decreases over time.
It is believed that the melted plasticizer diffuses inside the base
polymer matrix, and upon uniform distribution, yields a clear
adhesive coating. Such clarity of the activated adhesive will
remain for a prolonged period of time.
TABLE-US-00020 TABLE 19 Clarity of Film Label With an Activated
Adhesive Sample Haze (%) Label before activation 92.37 Activated
label after different dwell time (hr) 0.3 5.46 1 4.94 6 5.17 72
1.77
[0191] Referring to Table 19, the haze for a PET film by itself is
about 1%. These results indicate another feature of the preferred
embodiment adhesives relating to their optical clarity after
activation. Generally, the preferred embodiment adhesives exhibit
an optical clarity after activation characterized by relatively low
levels of haze. Generally, after activation, the adhesives exhibit
haze levels of less than 10%, more preferably less than 8%, more
preferably less than 6%, more preferably less than 4%, more
preferably less than 2%, and most preferably less than 1%. The
foregoing is with regard to adhesives that are generally free from
pigments, colorants, dyes, inks, or the like. As previously noted,
the present invention includes in certain embodiments, adhesives
that are free of such components.
[0192] In yet another series of investigations, carbon black was
incorporation into various layers of a label assembly. The label
assemblies were then activated as described herein. Temperature
measurements were obtained. As demonstrated in the results set
forth below, labels containing carbon black, regardless of the
particular layer location, reached higher temperatures than a
control label that was free of carbon black in any layer.
[0193] Specifically, label assemblies having primer layers and
adhesive layers received carbon black as set forth below in Table
20.
TABLE-US-00021 TABLE 20 Comparing Carbon Black (CB) Placed in
Different Layers of a Label Assembly Samples Power % Speed Act Time
First Run 2nd Run 3rd Run 4th Run Primer with 0.1% CB 100 4.0 (10.5
ips) 0.53 s 108 101 95 104 Primer with 0.2% CB 100 4.0 (10.5 ips)
0.53 s 112 106 101 112 Only Adhesive with CB 100 4.0 (10.5 ips)
0.53 s 112 105 100 109 No CB in any layer 100 4.0 (10.5 ips) 0.53 s
95 85 90 93
[0194] Each sample and the control (free of carbon black) was
exposed to energy emitting lamps, all set at the same power output.
Each sample and the control were moved past the emitters past the
emitters at the same rate thereby achieving the same activation
time for all samples and control. Maximum temperatures reached by
the labels were measured for four trials. The results are
graphically illustrated in FIG. 22.
[0195] The results of this investigation reveal that incorporation
of carbon black, even at relatively low concentration levels of
0.1% and 0.2%, resulted in significantly higher temperatures
occurring in the labels.
[0196] With respect to the previously noted testing, the following
procedures were followed for the noted measurements or
evaluations.
Peel Adhesion
[0197] The adhesive was coated at an approximate coat weight in the
specified range of 20 gsm to 40 gsm onto the selected paper
facestock. A barrier coating is coated on the paper if needed. The
coated materials are dried at 50.degree. C. for 10 minutes. The
resulting construction was die-cut into 25.times.204 mm (1.times.8
inch) sized strips. The strips were then subjected to an activation
thermally via MidWave IR, and applied centered along the lengthwise
direction to 50.times.152 mm (2.times.6 inch) brightly annealed,
highly polished stainless steel test panels, or a paper cardboard,
and rolled down using a 2 kg (4.5 lb), 5.45 pli 65 shore "A"
rubber-faced roller, rolling back and forth once, at a rate of 30
cm/min (12 in/min). The samples were conditioned for either 20
minutes or 24 hours in a controlled environment testing room
maintained at 23.degree. C. (73.degree. F.) and 50% relative
humidity. After conditioning, the test strips were peeled away from
the test panel in an Instron Universal Tester according to a
modified version of the standard tape method Pressure-Sensitive
Tape Council, PSTC-1 (rev. 1992), Peel Adhesion for Single Coated
Tapes 180.degree. Angle, where the peel angle was either
180.degree. or 90.degree. , i.e., perpendicular to the surface of
the panel, at a rate of 30 cm/min (12 in/min). The force to remove
the adhesive test strip from the test panel was measured in lbs/in.
All tests were conducted in triplicate.
Loop Tack
[0198] Loop tack measurements were made for samples cut to
25.times.204 mm (1.times.8 inch) sized strips which is subsequently
heat activated with MWIR radiation. Stainless steel or glass is
used as the substrate at a withdraw rate of about 305 mm/min (12
in/min), according to standard test 1994 TLMI Test L-1132, TLMI
Loop Tack Test, by the Tag and Label Manufacturers Institute Inc.
(TLMI), using an Instron Universal Tester Tester Model 4501 from
Instron (Canton, Mass.). Loop tack values were taken to be the
highest measured adhesion value observed during the test. All tests
were conducted in triplicate.
ARC SPAT Test (For Tack)
[0199] The SPAT test was developed by Avery Dennison Research
Center. Generally, this test procedure is as follows:
[0200] Samples are prepared by applying a double side coated tape
FT530 available from Avery Dennison onto a 1/36 inch aluminum
panel. The tape is rolled down twice with a 14.5 pound roller. The
liner of the double sided tape is then removed. A sample is then
positioned face down onto the exposed double coated tape. The
sample and tape pieces were rolled down twice using the 14.5 pound
roller. The rolled samples were then subjected to a 20 minute dwell
period before testing. The remaining release liners were then
removed prior to testing.
[0201] Machine set up was performed as follows. Texture Analyzer
TA.XT2i from Texture Technologies of New York, N.Y. was used. A
SPAT tester with 1 inch diameter stainless steel probe was used to
perform analysis with a test speed at 0.04 mm/sec, compressive
force at 4.5 Newtons, and contact time of 0.01 sec.
[0202] Additional details concerning SPAT test procedures are
described in Chuang HK; Chiu C.; Paniagua R. Avery Adhesive Test
yields more performance data than traditional probe, Adhesives Age
(10) 1997, 18-23.
Failure Modes
[0203] The following adhesive failure modes were observed for some
samples: "panel failure" (p)--the adhesive construction detached
from the panel cleanly, without leaving a residue; "panel staining"
(ps),--the adhesive construction detached cleanly, but left a faint
stain or "shadow" on the panel; "high panel staining (hps)--the
adhesive construction left a markedly noticeable stain on the
panel; "cohesive failure"(c)--the adhesive construction split
apart, leaving adhesive residue on the test panel and the
facestock; "facestock failure"(fs)--the adhesive completely
detached from the facestock, and transferred to the test panel;
"zippy" (z)--the adhesive construction detached from the panel with
a slip-stick, jerky release; and "mixed"--mixed failure modes.
Definition of PSA and Non-PSA
[0204] Both rubber-based and acrylic-based PSAs are known. In 1966,
C. Dalquist identified a 1 second creep compliance greater than
1.times.10.sup.-6 cm.sup.2/dyne as the efficient contact criterium
of a good PSA. A more recent discussion of PSAs in the Handbook of
Pressure Sensitive Adhesive Technology (2d Edition), D. Satas, ed.
(1989), (hereafter, "Handbook"), pages 172-176, incorporated by
reference herein, identifies glass transition temperature (T.sub.g)
and modulus (G') at the application (use) temperature as the most
important requirements for PSA performance. Both properties are a
function of the identities and amounts of monomers that comprise
the PSA polymer(s). Thus, poly(acrylic acid) is not a PSA, but a
copolymer of acrylic acid with high mole % of 2-ethylhexyl acrylate
is.
[0205] The typical values of G' and T.sub.g for label and tape PSAs
are described in the Handbook. For a tape, G' at room temperature
is approximately 5.times.10.sup.5 to 2.times.10.sup.6
dyne/cm.sup.2, and T.sub.g is approximately -15.degree. C. to
10.degree. C.; while labels have a lower value of G' at room
temperature, i.e., about 2.times.10.sup.5 to 8.times.10.sup.5
dyne/cm.sup.2. T.sub.g requirements for cold temperature,
permanent, and removable applications are different, as is known in
the art. Thus, cold temperature label PSAs generally require a
T.sub.g of from about -30.degree. C. to -10.degree. C.
[0206] All patents, published applications, and articles noted
herein are hereby incorporated by reference in their entirety.
[0207] It will be understood that any embodiment, aspect, or detail
thereof can be used with any other embodiment, aspect, or detail
thereof described herein. Thus, the various adhesive systems and
adhesive base polymers described herein can be used in conjunction
with any of the labels, label assemblies, systems, and methods
described herein.
[0208] The invention has been described and illustrated by
exemplary and preferred embodiments, but is not limited thereto.
Persons skilled in the art will appreciate that variety of
modifications can be made without departing from the scope of the
invention, which is limited only by the claims. Throughout the text
and the claims, use of the word "about" in relation to a range of
numbers is intended to modify both the low and the high values
stated.
[0209] The inventors hereby state their intent to rely on the
Doctrine of Equivalents to determine and assess the reasonably fair
scope of their invention as it pertains to any apparatus, system,
method or article not materially departing from but outside the
literal scope of the invention as set out in the following
claims.
* * * * *