U.S. patent application number 10/427532 was filed with the patent office on 2003-10-23 for faceless pressure-sensitive adhesive construction.
This patent application is currently assigned to Avery Dennison Corporation. Invention is credited to Conti, Norman A., Miekka, Frederick N., Scholz, William F., Su, Eric Chen-nan.
Application Number | 20030198737 10/427532 |
Document ID | / |
Family ID | 23025866 |
Filed Date | 2003-10-23 |
United States Patent
Application |
20030198737 |
Kind Code |
A1 |
Scholz, William F. ; et
al. |
October 23, 2003 |
Faceless pressure-sensitive adhesive construction
Abstract
Faceless PSA label constructions of this invention comprise a
flexible substrate having a release surface, and a layer of
pressure-sensitive adhesive disposed on the release surface. A
nonblocking continuous film that, in combination with the
pressure-sensitive adhesive is sufficiently self supporting, is
disposed over a surface of the layer of pressure-sensitive adhesive
to render the pressure-sensitive adhesive tack free. The continuous
film is selected from the group of film-forming polymers consisting
of polyamide resins, polyester resins, polyurethane resins,
polyacrylate resins, vinyl acetate resins and mixtures thereof
having a tensile strength of at least 200 psi, and a percent
elongation of at least 50. The continuous film can be applied
sequentially or simultaneously with the PSA. For purposes of
simultaneous application it is desired that the continuous film be
formed from a material having a hot melt viscosity that is within a
factor of about two times a hot melt viscosity for the PSA. The
completed faceless PSA label construction is adapted to receive and
retain printing or marking indicia directly onto a surface of the
continuous film.
Inventors: |
Scholz, William F.;
(Altadena, CA) ; Su, Eric Chen-nan; (Mentor,
OH) ; Conti, Norman A.; (Painesville, OH) ;
Miekka, Frederick N.; (Sierra Madre, CA) |
Correspondence
Address: |
JEFFER, MANGELS, BUTLER & MARMARO, LLP
1900 AVENUE OF THE STARS, 7TH FLOOR
LOS ANGELES
CA
90067
US
|
Assignee: |
Avery Dennison Corporation
Painesville
OH
|
Family ID: |
23025866 |
Appl. No.: |
10/427532 |
Filed: |
April 30, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10427532 |
Apr 30, 2003 |
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10179982 |
Jun 26, 2002 |
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6562402 |
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10179982 |
Jun 26, 2002 |
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09269115 |
Mar 19, 1999 |
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6461707 |
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Current U.S.
Class: |
427/208.4 |
Current CPC
Class: |
Y10T 428/31786 20150401;
C09J 2467/006 20130101; Y10T 428/24802 20150115; Y10T 428/14
20150115; Y10T 428/31551 20150401; Y10T 428/31725 20150401; C09J
2203/334 20130101; Y10S 428/914 20130101; G09F 3/10 20130101; C09J
2431/006 20130101; C09J 2477/006 20130101; G09F 19/22 20130101;
C09J 7/35 20180101; C09J 2433/006 20130101; C09J 7/22 20180101;
C09J 2475/006 20130101 |
Class at
Publication: |
427/208.4 |
International
Class: |
B05D 005/10 |
Claims
What is claimed is:
1. A pressure-sensitive adhesive construction comprising: a
flexible substrate; a pressure-sensitive adhesive material disposed
on the flexible substrate; a layer of releasable material
interposed between the flexible substrate and the
pressure-sensitive adhesive material; a continuous film layer
disposed onto a surface of the pressure-sensitive adhesive material
to render the pressure-sensitive adhesive nonblocking, the
continuous film layer being provided as a film-forming
thermoplastic material; wherein the combined pressure-sensitive
adhesive layer and continuous film layer is sufficiently self
supporting to facilitate conversion and dispensing of the
construction.
2. The pressure-sensitive adhesive construction as recited in claim
1 wherein the continuous film layer is printable.
3. The pressure-sensitive adhesive construction as recited in claim
1 wherein the continuous film layer has a thickness of less than
about 100 micrometers.
4. The pressure-sensitive adhesive construction as recited in claim
1 wherein the pressure-sensitive adhesive material and continuous
film layer have a combined thickness of less than about 225
micrometers.
5. The pressure-sensitive adhesive construction as recited in claim
4 wherein the pressure-sensitive adhesive material and continuous
film layer have a combined thickness of less then about 150
micrometers.
6. The pressure-sensitive adhesive construction as recited in claim
1 wherein the continuous film layer has a tensile strength of at
least 200 psi.
7. The pressure-sensitive adhesive construction as recited in claim
6 wherein the continuous film layer has a tensile strength of less
than about 2,000 psi.
8. The pressure-sensitive adhesive construction as recited in claim
1 wherein the continuous film layer has a percent elongation of at
least 50.
9. The pressure-sensitive adhesive construction as recited in claim
8 wherein the continuous film layer has a percent elongation of
less than about 500.
10. The pressure-sensitive adhesive construction as recited in
claim 1 wherein the film-forming thermoplastic used to form the
continuous film layer is selected from the group consisting of
polyamide resins, polyester resins, polyurethane resins,
polyacrylate resins, vinyl acetate resins, and mixtures
thereof.
11. A method for the continuous production of a pressure-sensitive
adhesive construction, the method comprising the steps of: applying
a layer of pressure-sensitive adhesive material onto a flexible
substrate, wherein a layer of releasible material is interposed
between the flexible substrate and the pressure-sensitive adhesive;
and applying a layer of film-forming thermoplastic material onto a
surface of the pressure-sensitive adhesive to render the
pressure-sensitive adhesive material tack free; wherein the
combined layer of pressure-sensitive adhesive material and layer of
film-forming thermoplastic material is sufficiently self supporting
to facilitate conversion and dispensing of the construction.
12. The method as recited in claim 11 further comprising, prior to
the step of applying the pressure-sensitive adhesive material, the
step of dispensing the flexible substrate in the form of a
continuous web.
13. The method as recited in claim 11 further comprising,
subsequent to the step of applying the layer of film-forming
thermoplastic material, the step of collecting the
pressure-sensitive construction in the form of a continuous
web.
14. The method as recited in claim 11 wherein the steps of applying
are carried out in a single step simultaneously.
15. The method as recited in claim 11 wherein the film-forming
thermoplastic material is applied before the pressure-sensitive
adhesive material is fully developed.
16. The pressure-sensitive adhesive construction as recited in
claim 11 wherein the film-forming thermoplastic material is
selected from the group consisting of polyamide resins, polyester
resins, polyurethane resins, polyacrylate resins, vinyl acetate
resins, and mixtures thereof.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 10/179,982, filed on Jun. 26, 2002, which was
a a divisional application of U.S. patent application Ser. No.
09/269,115, filed Mar. 19, 1999, which claimed the priority of
International application No. PCT/US97/17404 filed on Sep. 26,
1997, which claimed the benefit of U.S. Provisional application No.
60/026,819.
FIELD OF THE INVENTION
[0002] The present invention relates to pressure-sensitive adhesive
constructions used for making tags, labels and the like and, more
particularly, to pressure-sensitive adhesive constructions
comprising a thin continuous film disposed onto a layer of a
pressure-sensitive adhesive that renders an underlying
pressure-sensitive adhesive layer surface tack free, and that is
printable, convertible and dispensable.
BACKGROUND OF THE INVENTION
[0003] Pressure-sensitive adhesive (PSA) constructions such as
labels, tapes, decals and the like are known in the art. For
example, PSA label constructions are commonly used to apply a
particular face stock having a specific nature of printing to an
object or article, and are especially useful where objects having
low surface energies are to be labeled. PSA label constructions
typically comprise a liner, a PSA layer disposed onto the liner,
and a face stock laminated onto the PSA layer. The face stock is
typically made from a web or sheet of paper, cardboard or plastic
and is applied or laminated to the PSA layer sequentially at some
time after the application of the PSA layer. The face stock is
printed on with information or other indicia before or after it is
laminated onto the PSA layer. The conventional PSA label
construction is applied to an article surface or other substrate
surface by removing the liner to expose the PSA layer and placing
the PSA layer into contact with the desired surface, wherein the
face stock remains attached to the opposite surface of the PSA
layer.
[0004] In the manufacture and production of PSA constructions, a
substantial amount of the overall cost involved is in the material
costs for the face stock, be it paper, cardboard, or plastic.
Additionally, where the tag or label is to be adhered to a
contoured or irregular surface, and where a high degree of
flexibility is desired, the rigidity of the face stock may
interfere with the application and the adherence of the tag or
label. Further, conventional PSA label constructions require
sequential processing of the PSA layer and face stock, thereby
lengthening the amount of time needed to manufacture a completed
PSA label construction.
[0005] It is, therefore, desired that a PSA construction be
constructed for use as a label, tag, tape, decal and the like that
avoids the need to use a conventional face stock formed from paper,
cardboard or plastic. It is desired that the PSA label construction
have printability, convertibility and dispensability properties
that are better than or equal to that of PSA label constructions
having a conventional face stock. It is also desired that such PSA
label construction be designed in a manner that reduces the amount
of manufacturing time needed to complete the same, when compared to
a PSA construction comprising a conventional face stock.
SUMMARY OF THE INVENTION
[0006] Faceless PSA label constructions of this invention are
constructed without having a conventional face stock for printing
indicia thereon but, rather comprise a thin, printable, convertible
and dispensable continuous film disposed on an underlying PSA
layer, that is preferentially removed with the PSA from a release
liner to facilitate application onto a designated substrate. In an
example embodiment, faceless PSA label constructions of this
invention comprise a flexible substrate having a release surface,
and a layer of pressure-sensitive material disposed on the release
surface, and a continuous film is disposed over a surface of the
layer of pressure-sensitive adhesive to render the
pressure-sensitive adhesive tack free. The final film-forming layer
is derived from a coatable or extrudable fluid with film-forming
properties that is delivered to the pressure-sensitive adhesive
layer in either 100 percent solids form, in an emulsion latex, or
dissolved in a suitable solvent. Upon cooling or with removal of
the water or solvent, a continuous, printable, self supporting film
with measurable tensile, elongation, and tear properties is
formed.
[0007] The continuous film is selected from the group of
film-forming polymers consisting of polyamide resins, polyester
resins, polyurethane resins, polyacrylate resins, vinyl acetate
resins, and mixtures thereof. Because it is desired that the
continuous film be self supporting, the continuous film has a
tensile strength of at least 200 psi, and a percent ultimate
elongation of at least 50. The continuous film can be applied
sequentially or simultaneously with the pressure-sensitive
adhesive. For purposes of simultaneous application it is desired
that the continuous film be formed from a material having a hot
melt viscosity that is within a factor to two times that of a hot
melt viscosity for the PSA. The completed faceless PSA construction
thus formed is capable of receiving and retaining printing and
marking indicia directly onto the surface of the continuous
film.
[0008] Faceless PSA constructions of this invention can be used as
a label, tag, tape, decal and the like that avoids the need to use
a conventional face stock formed from paper, cardboard or plastic,
thereby eliminating application limitations regarding the same,
e.g., now permitting application of label onto substrates having
irregular surfaces. PSA constructions of this invention are self
supporting and display printability, convertibility and
dispensability properties that are better than or equal to that of
PSA label constructions having a conventional face stock. PSA
constructions of this invention also reduce manufacturing costs,
avoiding the need to use a separate paper, cardboard, metallic or
plastic face stock, and increase manufacturing efficiency by
permitting simultaneous application of the continuous film layer
and PSA, when compared to a PSA construction comprising a
conventional face stock.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] These and other features and advantages of the present
invention will become appreciated as the same becomes better
understood with reference to the specification, claims and drawings
wherein:
[0010] FIG. 1 is semi-schematic side elevation of a method of
manufacturing a prelaminate PSA label construction;
[0011] FIG. 2 is a semi-schematic side elevation of a method of
applying a conventional face stock to the PSA label construction of
FIG. 1 to form a laminated PSA label construction;
[0012] FIG. 3 is a semi-schematic side elevation of a method of
converting the laminated PSA label construction of FIG. 2;
[0013] FIG. 4 is a cross-sectional side view of a faceless PSA
label construction prepared according to principles of the
invention;
[0014] FIG. 5 is a semi-schematic side elevation of a first method
making the faceless PSA label construction of FIG. 4;
[0015] FIG. 6 is a semi-schematic side elevation of a second method
of making the faceless PSA label construction of FIG. 4; and
[0016] FIG. 7 is a semi-schematic side elevation of a method for
heat treating a continuous film material layer of faceless PSA
label constructions of this invention.
DETAILED DESCRIPTION OF THE INVENTION
[0017] The present invention is directed to thin, printable,
convertible and dispensable PSA constructions which do not have a
conventional face stock formed from paper, cardboard, or plastic
laminated to a PSA layer. PSA constructions of this invention
generally comprise a first flexible substrate, a layer of
releasable material disposed on a surface of the flexible
substrate, a PSA disposed on the layer of releasable material, and
a thin layer of film-forming material (FFM) disposed onto a surface
of the PSA layer that renders the PSA layer surface tack free, and
that is adapted to be printed or otherwise marked upon. PSA
constructions of this invention are referred to as being Afaceless@
because the FFM forms the substrate that is printed or marked upon,
rather than using a conventional face stock that is subsequently
laminated to the PSA layer. The design of a faceless PSA
construction, avoiding the need to use such a conventional face
stock, reduces the material costs for such PSA construction and
reduces manufacturing time associated with producing the same.
[0018] FIG. 1 illustrates a conventional prelaminate PSA label
construction 10 comprising a liner 12 having disposed thereon at
station 14 a layer of releasable material 16, forming a release
liner. A PSA layer 18 is disposed on the layer of the releasable
material 16 at station 20. Referring to FIG. 2, a conventional face
stock 22, in sheet stock or roll stock form made from paper,
cardboard, plastic and the like, is disposed on a surface of the
PSA layer 18 to form a completed conventional PSA label
construction. Typically, the layer of releasible material 16 and
PSA layer 18 are manufactured and laminated together with the face
stock 22 during a single process, e.g., by a roll coating and
lamination process or by a die coating and lamination process. As
illustrated in FIG. 2, the face stock 22 is laminated to the PSA
layer 18 sequentially, after the PSA layer is applied.
[0019] The completed or laminated PSA label construction is
distributed to a converter where it is printed, cut and stripped,
e.g., by conventional die cutting and matrix stripping methods, to
form the desired shape and size label. Thus for example, FIG. 3
illustrates the die cutting of the face stock 22 at a station 24
into a series of PSA labels 26 of desired shape and size, carried
by the release liner 16.
[0020] For purposes of reducing material costs and manufacturing
time, and increasing PSA construction application flexibility, PSA
constructions of this invention are constructed without the use of
a conventional face stock. Instead, PSA constructions of this
invention comprise a layer of FFM in the form of a thin continuous
film that is formed on and disposed over PSA layer and that is
printable, convertible and dispensable, thereby eliminating the use
of conventional face stock materials. Dispensing of the thicker
label construction is achieved by the traditional peel-plate
method, or the equivalent, and dispensing for the thin label
construction is achieved by techniques described in U.S. Pat. Nos.
4,217,164 and 4,303,461, which are incorporated herein by
reference.
[0021] With reference now to FIG. 4, an example embodiment of a
faceless PSA label construction 28, prepared according to
principles of this invention, includes a substrate 30 and a layer
of releasable material 32 disposed on a surface of the substrate
30. It is to be understood that the substrate 30 may be in the form
of any material suitable to act as a carrier for the construction.
Preferred substrates include flexible materials that are selected
from the group of stocks selected from sheet stock and roll or web
stock. A particularly preferred substrate is a web stock in the
form of a liner having a release material disposed thereon, thereby
forming a release liner. A particularly preferred release liner is
one that is commercially available from, for example, Rhinelander
Paper of Rhinelander, Wis. under the product name Rhi-Liner 12,
that has a thickness of about 65 micrometers and has a 42 pound per
ream basis weight.
[0022] Suitable releasable materials 32 include those materials
with a low surface free energy that have a low affinity for the
PSA, thereby allowing the PSA to be peeled away without cohesive
failure. Preferred releasable materials are selected from the group
of silicone-containing materials. A particularly preferred
silicone-containing material for forming the layer of releasable
material is commercially available from, for example, General
Electric Silicones of Waterford, N.Y. under the product name GE
6000.
[0023] A layer of PSA 34 is disposed on a layer of the releasable
material 32, and a layer of FFM 36 is disposed on a surface of the
PSA layer 34. The PSA layer 34 has a body portion and has a surface
portion that is oriented immediately adjacent the layer of FFM 36.
The FFM layer 36 renders the underlying PSA layer 34 tack free,
thereby forming a nonblocking faceless PSA construction that
enables subsequent handling or treatment of the construction
without it adhering to itself or to any other adjacent surface. The
tack-free surface is designed to accommodate printing indicia 38
directly thereon. The FFM 36 layer is in the form of a continuous
film that completely covers the underlying PSA layer, and renders
the faceless PSA construction completely nonblocking. Faceless PSA
constructions of this invention are nonblocking up to a minimum
temperature of at least 50 C, and in some instances up to about 70
C, for a 24 hour period under a pressure of about 40 kPa, as will
be discussed in greater detail below.
[0024] It is important that faceless PSA constructions of this
invention display such nonblocking characteristics to facilitate
removing or separating the collected and/or stored faceless PSA
construction from contiguous layers after it has been manufactured
without causing the release liner to be pulled free of the PSA
layer. The use of the releasable material on the release liner
allows the release liner to be easily removable from the PSA layer
to facilitate attachment of the completed, i.e., laminated, PSA
construction to a desired article. Adhesive interference or
blocking between the FFM and an adjacent backside surface of the
release liner is not desired because it results in the release
liner being pulled away from the PSA layer during the removal or
separation operation, thereby rendering the faceless PSA
construction useless.
[0025] It is desired that the FFM layer be formed from a material
that is capable of being used with a variety of conventional PSAs,
including silicone-based PSAs, rubber-based PSAs, and acrylic-based
PSAs, without interfering with the desired performance
characteristics of the PSA. PSAs useful in forming faceless PSA
constructions of this invention include those that are
conventionally used in forming PSA constructions, such as
rubber-based, silicone-based, and acrylic-based PSAs. Preferred
adhesives systems are described in detail in U.S. patent
application Ser. No. 07/755,585 filed Sep. 3, 1991, abandoned on
Sep. 25, 1992, and incorporated herein by reference.
[0026] PSAs useful in forming faceless PSA constructions according
to principles of this invention can include:
[0027] S-246--a hot melt rubber based PSA that is manufactured by
the Fasson Division of Avery Dennison Corporation. S-490--An
acrylic emulsion PSA that is manufactured by the Chemicals Division
of Avery Dennison Corporation.
[0028] The layer of PSA material can be applied to the substrate
for example in the form of a hot melt, an emulsion or aqueous
dispersion, as a solvent solution, or as a film membrane. The
method that is used to apply the PSA material depends on the
physical form of the PSA, and can include spray, roll, and die
application methods. In preferred embodiments, the PSA material is
applied in the form of a hot melt, solution, or emulsion by die
application method. As will be discussed below, multi-die
application methods can be used to simultaneously apply the PSA
material along with the FFM.
[0029] The type of FFM that is selected may vary depending on the
type of material that is used to form the PSA layer. For example,
it may be desired that the FFM have a solubility parameter that is
inconsistent or incompatible with that of the PSA to prevent
migration between the two layers when applied simultaneously.
Different methods can be used to apply the FFM to the surface of
the PSA layer, depending on the type of FFM that is selected.
Generally speaking, the methods described above for applying
different forms of the PSA material can also be used to apply the
same forms of the FFM. For example, FFMs in the form of aqueous
dispersions can be applied by conventional coating methods such as
roll coating, spray coating, die coating and the like, or by Meyer
rod process; FFMs in the form of a solution or emulsion can be
applied by die, spray, or roll process; and FFMs in the form of a
hot melt can be applied by roll, spray or die process.
[0030] If desired, the application methodology used for the FFM can
be independent of both the FFM chemistry and the particular method
employed to apply the PSA layer. However, for purposes of
manufacturing efficiency, it is generally desirable to use a FFM
that is in the same form as the PSA material so that the same
application methodology can be used for each. For example, when the
PSA is in the form of a hot melt or a solution that is applied by
die process, it may be desired that the FFM also be in the form of
a hot melt or solution to facilitate its application by a die
process, e.g., by multi-die process.
[0031] As discussed above, suitable techniques for applying the FFM
onto the surface of the PSA layer include roll, spray, Meyer rod,
electrostatic, and die process depending on the particular form of
the FFM as mentioned above. The application techniques generally
fall into the category of either being a multi-step or sequential
coating process, e.g., application of first the PSA layer and then
the FFM, or a single-step or simultaneous process, e.g.,
application of the PSA and FFM together. In the multi-step process,
the FFM can be applied to the surface of the PSA layer, after the
PSA has been applied to the layer of releasable material on the
release liner, in the form of a hot melt, aqueous dispersion, or
solution by roll, spray, electrostatic, or die process. In the
single-step process, die technology is preferably used to apply the
FFM onto the PSA layer simultaneously with applying the PSA layer
onto the layer of releasable material, in the form of a solution,
emulsion or hot melt.
[0032] FIG. 5 illustrates a first method of applying the PSA layer
and FFM layer onto a substrate in the form of a web stock by a
multi-step die or tandem die process 40, where the PSA layer 42 is
applied to a release liner 44 in the form of a solution, emulsion
or a hot melt, and the FFM layer 46 is subsequently applied to the
PSA layer 42 as a solution, emulsion or a hot melt. This first
method is illustrative of one that can easily be implemented using
existing PSA coating equipment to permit subsequent application of
the FFM. The PSA layer 42 is applied to the layer of releasable
material on the release liner 44 by a PSA coating station 48, which
contains a volume of PSA material 50. A FFM coating station 52 is
disposed downstream from the PSA coating station 48 and comprises a
volume of FFM 54 for depositing onto the PSA layer 42.
[0033] In the event that the PSA layer and FFM layer are each
applied in the form of a hot melt, it may be desirable that a
cooling platen (not shown) or the like be placed between the PSA
coating station 48 and the FFM coating station 52, to cool the PSA
layer 42 to prevent migration of the FFM therein. It may also be
desirable to place a cooling platen (not shown) or the like after
the FFM coating station 52 to cool the FFM 46 to ensure that it is
tack free before the faceless PSA construction is wound on a
collection roll 56.
[0034] In the event that both the PSA layer and FFM layer are
applied in the form of a solution or emulsion, it may be desirable
to place an evaporator (not shown) or the like between the PSA
coating station 48 and the FFM coating station 52, to drive the
solution out of the PSA layer to prevent bubble formation after
application of the FFM layer. It may also be desirable to place an
evaporator (not shown) or the like after the FFM coating station 52
to drive the evaporatable species out of the FFM layer 46 before
the faceless PSA construction is wound on the collection roll
56.
[0035] As a continuous roll of the release liner 44 is unwound or
dispersed from a pay out roll 58, the PSA coating station 48
deposits a predetermined thickness of PSA material 50 onto the
layer of releasable material on the release liner 44, forming a PSA
layer 42 thereon. The FFM coating station 52 deposits a
predetermined thickness of the FFM 54 onto the surface of the PSA
layer 42, as the faceless PSA construction travels in a continuous
web through the FFM coating station 52, forming a FFM layer 46
thereon.
[0036] In an example embodiment, the PSA layer 42 has a coat weight
in the range of from about 5 to 125 grams/square meter (g/m.sup.2),
or has a thickness in the range of from about 5 to 125 micrometers
assuming a PSA density of about one. It is desired that the FFM
layer 46 have a coat weight in the range of from about 0.5 to 100
g/m.sup.2 (0.5 to 100 micrometers thickness assuming a density of
about 1), where a preferred FFM layer coat weight is in the range
of from about 1 to 50 g/m.sup.2 (1 to 50 micrometers thickness),
and where a most preferred FFM layer coat weight is in the range of
from about 4 to 35 g/m.sup.2 (4 to 35 micrometers thickness).
[0037] It is to be understood that the coat weight and layer
thickness of both the PSA and FFM may vary depending on the
particular faceless PSA construction application. A FFM having a
coat weight and/or thickness in the desired range provides a
desired degree of protection against adhesion between the PSA layer
and an adjacent backside surface of a release liner when in the
stored position, to permit storage and transporting of the
collected faceless PSA construction for further processing, e.g.,
printing, conversion or the like.
[0038] A key feature of faceless PSA constructions of this
invention is the ability of the thin FFM layer to provide the
structural properties necessary to facilitate conversion and
dispensing without the use of a conventional face stock. A FFM
having a coat weight and/or thickness in the desired range provides
a faceless PSA construction that is, in combination with the
pressure-sensitive adhesive layer, sufficiently self supporting to
facilitate conversion and dispensing.
[0039] If desired, the coat weight and/or thickness of either the
FFM or PSA layer can be metered by use of a Meyer rod that can be
placed after each respective coating station. To ensure accurate
monitoring of the thickness of the FFM, ultraviolet (UV)
chromophores can be added to the FFM to allow visual observation of
coating quality during the application process, and to allow
monitoring of the coat weight by on-line use of a combination
ultraviolet and radio frequency gauge. A particularly preferred UV
chromophore is Leucopure EGM available from Clariant Chemicals.
[0040] After the faceless PSA construction has passed the FFM
coating station 52 and the FFM 54 has been applied, the faceless
PSA construction is routed to and is collected on the collection
roll 56. When a desired quantity of the faceless PSA construction
has been manufactured, the collection roll 56 is removed from the
process and is stored for subsequent processing, e.g., printing,
and/or conversion, during a separate operation at either the same
or at a different geographic location, thereby providing enhanced
manufacturing flexibility. Alternatively, rather than being
collected, the completed faceless PSA construction can be routed
for printing or other marking process and/or conversion during the
same manufacturing operation.
[0041] A second method of applying the PSA layer and FFM by a
single-step multi-die process 60 is illustrated in FIG. 6. A dual
die station 62, comprising a PSA die chamber 64 and a FFM die
chamber 66, comprises a quantity of PSA 68 and FFM 70 in respective
separated compartments. The dual die station 62 is used to deposit
both the PSA and the FFM, in the form of either a hot melt,
solution or emulsion, simultaneously in one step.
[0042] Although FIG. 6 illustrates a single-step multi-die process
comprising a dual die station for applying the PSA layer and FFM
layer, it is to be understood that the multi-die process may
comprise a die station having more than two die compartments,
depending on the number of layers to be deposited onto the release
liner. Multi-die application methods useful for applying both the
PSA layer and the FFM layer are further described in Published PCT
International Application Nos. PCT/US95/11807; PCT/US95/11733;
PCT/US95/11734; and PCT/US95/11717, which are herein incorporated
by reference.
[0043] As a continuous roll of the release liner 72 is unwound from
a pay out roll 74, the PSA die chamber 64 deposits a thickness of
the PSA material 68 onto the layer of releasable material on the
release liner 72, forming a PSA layer 76 thereon. At the same time
that the PSA material is being deposited, a thickness of the FFM 70
is deposited by the FFM die chamber 66 onto the just-formed surface
of the PSA layer 76, forming a FFM layer 78 thereon. The completed
faceless PSA construction is either routed for subsequent printing
and/or conversion, or is collected on a collection roll 80.
[0044] As discussed above, subsequent printing and conversion of
the faceless PSA construction may occur at the same geographical
location where the faceless PSA construction is manufactured, or
may occur at a different geographical location. Alternatively,
rather than being collected, the completed faceless PSA
construction can be routed for printing and/or conversion during
the same manufacturing operation.
[0045] In the event that the PSA layer and FFM layer are applied as
a hot melt, a cooling platen (not shown) or the like can be placed
between the dual die station 62 and the collection roll 80 to
reduce the temperature of the FFM layer 78 to ensure that it is
tack free before being collected on the collection roll 80, thereby
avoiding unwanted sticking to the adjacent backside surface of the
release liner.
[0046] In the event that the PSA layer and FFM layer are applied as
a solution or emulsion, an evaporator (not shown) or the like can
be placed between the dual die station 62 and the collection roll
80 to drive off the evaporatable species from the faceless PSA
construction before being collected on the collection roll 80 to
avoid unwanted sticking to the adjacent backside surface of the
release liner.
[0047] After the FFM layer has been deposited onto the underlying
PSA layer, the faceless PSA construction, it may be desirable to
further heat the FFM layer to ensure that any streaks, surface
imperfections or other voids that may have been formed therein and
that expose the underlaying PSA layer are removed so that the FFM
layer forms an imperforate continuous film covering the PSA layer
before being collected. Such further heat treating step is helpful
when the FFM has a high solids content either during or after its
application. A FFM applied as a hot melt, by either multi-step or
tandem die process, has a solids content of approximately 100
percent. Streaks or other surface imperfections that expose the
underlaying PSA layer may be formed in the FFM during its
application by particulate matter in the die. Because of its high
solids content, the FFM is unable to readily migrate or flow after
it is applied to fill in such streaks or imperfections in the FFM
layer. If left untreated, the exposed PSA layer will be allowed to
make contact with a backside surface of the release liner when the
faceless PSA construction is collected on the collection roll.
[0048] Contact between the PSA layer and the contiguous release
layer backside surface will cause the faceless PSA construction to
adhere to such backside surface, thereby making the faceless PSA
construction difficult to unwind and causing the PSA layer to bond
permanently to the release layer backside surface. Once the PSA
layer is pulled away from its underlaying release layer and is
transferred to the backside surface of the contiguous release layer
the PSA faceless construction is ruined and is unsuited for
lamination.
[0049] A FFM that is applied as a solution or as an emulsion, by
either multi-step or tandem die process, will have a solids content
of approximately 100 percent after the solvent or emulsifying agent
has been evaporated away. Like the hot melt applied FFM layer, the
die process that is used to apply a solvent or emulsion FFM may
also create streaks or other imperfections in the FFM that exposes
the underlaying PSA layer. Streaks or imperfections in the FFM may
be formed in solution or emulsion applied FFMs when either the FFM
does not adequately wet the underlying PSA layer, or when the FFM
becomes dewetted with the underlaying PSA layer during further
processing, e.g., during evaporation. If left untreated, the
streaks or imperfections could cause a catastrophic failure of the
faceless PSA construction as discussed above during the unwinding
process by PSA layer transferal.
[0050] Streaking or the formation of other imperfections in the
FFM, that expose the underlaying PSA layer, are eliminated by heat
treating the faceless PSA construction at a stage after application
of the FFM layer but before the faceless PSA construction is
collected on a collection roll. Heat treating the FFM layer at this
point causes the FFM to soften, reflow and migrate to fill in any
streaks or imperfections.
[0051] Referring to FIG. 7, where the FFM layer 82 is applied as a
hot melt, it is preferably heat treated by exposure to a radiation,
convention or conduction heating means as indicated generally by
arrow 84 to a flow temperature that is below the FFM liquification
temperature but sufficiently high to cause the FFM to reflow and
fill any streaks or imperfections. In an example embodiment, the
FFM layer is heated to a temperature of approximately 150 C (300 F)
to cause it to flow a sufficient amount to fill all streaks or
imperfections that expose the underlying PSA, and thereby produce a
FFM layer in the form of an imperforate continuous film that
completely covers the underlaying PSA layer.
[0052] Referring still to FIG. 7, where the FFM layer 82 is applied
in the form of a solvent or emulsion, the FFM layer is heat treated
by exposure to radiation, convention or conduction heating as
indicated by arrow 84. Heat treating the FFM layer 82 can take
place independently from the evaporation operation, and can be
effected by a heating means that is independent of that used for
the evaporating operation. Alternatively, the step of heat treating
the FFM layer 82 can be carried out as part of the evaporation
operation by further heating the FFM after evaporation to a flow
temperature that is below the FFM liquification temperature but
sufficiently high to cause the FFM to flow and fill any streaks or
imperfections. In an example embodiment, the FFM layer is heated to
a temperature of approximately 150 C (300 F) after being evaporated
to cause it to flow a sufficient amount to fill all streaks or
imperfections that expose the underlying PSA, and thereby produce a
FFM layer in the form of an imperforate continuous film the
completely covers the underlaying PSA layer.
[0053] In a preferred embodiment, where streaks or other
imperfections are discovered to be present in the FFM layer, the
FFM is heat treated in three continuous zones using forced air
convection ovens. The first zone was heated to 100 C, the second to
120 C, and the third to 140 C. Each oven was approximately eight
feet in length. The coated laminate traveled at a speed of
approximately 50 feet per minute, giving a residence time of
approximately 9.6 seconds through each zone.
[0054] Samples of faceless PSA constructions prepared according to
the conditions discussed below were tested to determine the surface
roughness of the FFM layer before and after being heat treated in
the manner discussed immediately above. The FFM layer of a non-heat
treated faceless PSA construction had an average surface roughness
of approximately 0.87 micrometers, and a RMS surface roughness of
approximately 1.08, when measured using a Wyco surface morphology
microscope scanned at a magnification of approximately 5.3 times,
using a scan area of approximately 1170.times.880 micrometers, and
using a point-to-point distance of approximately 3.10 micrometers.
The FFM layer of a heat treated faceless PSA construction had an
average surface roughness of approximately 0.58 micrometers, and a
RMS surface roughness of approximately 0.71 micrometers under the
same measurement conditions. Based on these results, the process of
heat treating the FFM layer as described herein reduced the surface
roughness of the FFM layer by approximately 40 percent, thereby
evidencing the filling and minimization of streaks and other
imperfections in the FFM layer. Additionally, the heat treated FFM
layer also displayed a surface finish that was glossier than that
of the non-heat treated faceless PSA construction.
[0055] A key feature of faceless PSA constructions of this
invention is that they do not rely on the use of conventional face
stocks for purposes of proving a substrate for accommodating
printing and marking indicia. This permits PSA construction to be
manufactured at a lower material cost than convention PSA
constructions comprising such conventional face stocks. Faceless
PSA constructions of this invention also promote manufacturing
efficiency by both enabling the FFM to be applied with readily
available coating machinery, thereby eliminating the need for
subsequent laminating machinery, and by enabling simultaneous
application of the FFM and PSA, thereby avoiding the need for
sequentially applying the face stock. Faceless PSA constructions of
this invention also promote application flexibility, enabling use
of the PSA construction in applications where the construction
adherend has a contoured or irregular shape and a high degree of
flexibility is required.
[0056] While particular methods for manufacturing faceless PSA
constructions have been described and illustrated, it is to be
understood that conventional methods for applying PSA materials,
and for making PSA constructions, can also be adapted to
manufacture faceless PSA constructions of this invention. Suitable
FFMs useful for forming faceless PSA constructions of this
invention include materials that are: (1) coatable or extrudable;
(2) continuous film formers; (3) capable of completely and
uniformly covering the underlying PSA layer; and (4) that are, in
combination with the PSA, sufficiently self supporting to
facilitate printing, conversion, and dispensing. A key feature of
FFMs useful for forming faceless PSA constructions is that they
cure, dry or cool to both form a completely nonblocking layer and,
in combination with the PSA, are sufficiently self supporting,
having properties of tensile strength, elongation and tear. Example
FFMs include thermoplastic polymers selected from the group
including, but not limited to, polyamide resins, polyester resins,
polyurethane resins, polyacrylate resins, vinyl acetate resins, and
mixtures thereof.
[0057] When the FFM used to form faceless PSA construction is
applied in the form of a hot melt, solution, or emulsion by dual
die method, it is desired that the FFM have a hot melt, solution,
or emulsion viscosity during the coating operation that is within a
viscosity window similar to that of the PSA material. This is
desired to enable the FFM to form a continuous film that completely
and uniformly covers the underlying PSA layer, thereby forming a
nonblocking faceless PSA construction. The simultaneous delivery of
the PSA and FFM is possible using conventional coating equipment
and a multi-die or an extruder if the viscosities between the
respective materials are relatively close and the two materials do
not significantly interact with each other. When applied
simultaneously using conventional die methods it is desired that
the PSA and FFM have a hot melt viscosity and melting temperature
that are relatively similar. The use of polyamide resins in
particular are suitable FFMs for conventional hot melt adhesives
because their viscosities are similar in magnitude at the
application temperatures used to deliver the respective
materials.
[0058] For example, when the PSA is a conventional hot melt
adhesive, the melting temperatures of the PSA are in the range of
from about 150 C to about 200 C, and preferably in the range of
from about 165 C to about 180 C. It is, therefore, desired that the
FFM selected for use with such PSA have a melt temperature below
about 200 C, and preferably in the range of from about 150 C to 180
C.
[0059] Conventional hot melt PSAs have a Brookfield viscosity in
the range of from about 25,000 to 90,000 centipoise at 175 C. It is
desirable that the FFM that is used with such PSA have a viscosity
that is within a factor of two times that of the PSA. A FFM having
a hot melt, solution, or emulsion viscosity more than about two
times below that of the PSA material can produce a FFM layer having
film defects that prevent complete and uniform PSA layer coverage.
A FFM having a hot melt, solution, or emulsion viscosity of more
that about two times higher than the PSA material can produce a FFM
layer that also displays film defects, thereby preventing complete
and uniform PSA layer coverage. Preferred FFMs have a hot melt,
solution, or emulsion viscosity window during coating by dual die
process that is within a factor of about two times the viscosity of
the just-applied PSA material.
[0060] It is desired that the FFM selected also have a chemistry
that is not compatible with the underlying PSA material to prevent
its migration into the PSA layer when deposited onto the PSA layer.
Migration of the FFM into the PSA layer is not desired because it:
(1) impairs the ability of the FFM to form a completely nonblocking
layer; (2) interferes with the adhesive properties of the PSA
layer; and (3) reduces the ability of the FFM layer to serve as a
substrate for receiving and retaining printing and marking
indicia.
[0061] It is desired that the FFM layer have a tensile strength of
at least 200 psi, and more preferably in the range of from 200 to
2,000 psi. A FFM having a tensile strength less than about 200 psi
can produce a faceless PSA construction that is difficult to
convert by die cut and matrix strip methods at cost effective web
speeds, e.g., at web speeds greater than about 50 feet per minute.
A FFM layer having a tensile strength greater than about 2,000 psi
can produce a faceless PSA construction that is difficult to die
cut and matrix strip, depending on the particular type of PSA and
FFM, and on the particular coat weights of the same.
[0062] It is desired that the FFM layer have a percent ultimate
elongation of at least 50, and more preferably in the range of from
about 50 to 500. A FFM having a percent ultimate elongation less
than about 50 can produce a faceless PSA construction that is
difficult to convert due to tearing and the like. A FFM layer
having a percent ultimate elongation greater than about 500 can
produce a faceless PSA construction that is difficult to convert by
die cutting and matrix stripping, depending on the type of PSA and
FFM, and on their respective coat weights.
[0063] Preferred film-forming resins useful for forming the FFM
layer are thermoplastic polyamide resins. Particularly preferred
polyamide resins are those commercially available, for example,
from Union Camp of Wayne, N.J. under the Uni-Rez product line.
Dimer-based polyamide resins available from Bostik, Emery, Fuller,
Henkel (under the Versamid product line) to name a few can also be
used. Other suitable polyamides include those produced by
condensing dimerized vegetable acids with hexamethylenediamine.
Referring to the Union Camp materials, the particular Uni-Rez
polyamide resin or resin blend that is selected ultimately depends
on the particular faceless PSA construction physical properties
desired, and may depend on the type and viscosity of the PSA
material used to form the underlying PSA layer.
[0064] In an exemplary embodiment, where the underlying PSA
material is S-246, a preferred FFM formed from the polyamide resin
comprises a blend of Uni-Rez resins that both provides a desired
viscosity within the range described above, and produces a
self-supporting surface having desired properties of tensile
strength, elongation and peel. For example, a 1:3 mixture of the
Uni-Rez 2620 and 2623 polyamide resins produces a blend having a
Goettfert viscosity curve at 155.quadrature.C, within a shear rate
range of from 0 to 40,000 seconds.sup.-1, that is within a factor
of about two times the Goettfert viscosity curve at
155.quadrature.C for the S-246 PSA material.
[0065] Physical properties of FFM layers formed from the Uni-Rez
product line, such as viscosity, tensile strength (ASTM D1708),
percent ultimate elongation (ASTM D1708), and peel (ASTM D1876),
are set forth in Table 1 below.
1TABLE 1 Brookfield FFM Type Softening Viscosity Tensile Percent
(Uni-Rez Point (cPs at Strength Ultimate product code) (.degree.
C.) 190.degree. C.) (Psi) Elongation Peel (pli) 2620 105 900 1,000
50 0 2623 136 6,500 1,000 400 0 2665 165 11,000 2,000 500 0 2695
128 5,000 200 175 30 2620 & 2623 128 5,100 1,000 313 0 (blend
at 1:3)
[0066] After the FFM layer is deposited on the faceless PSA
construction the completed construction can either be collected for
future printing and converting at a different time and/or
geographic location, or can be routed to another station for
printing and/or converting during the same operation. In an example
process, the completed faceless PSA construction is collected for
future printing and conversion. Before printing it is desired that
the faceless PSA construction be treated to make the surface of the
FFM layer more receptive to subsequent printing or marking. In an
example embodiment, the faceless PSA construction is treated by
conventional surface treatment method, such as corona treatment and
the like, to increase the surface energy of the FFM layer to
facilitate wetting during the printing process.
[0067] After the faceless PSA construction is surface treated it is
passed to one or more printing stations where the treated FFM layer
surface is printed upon by conventional method, such as by Gravure
method, Flexo method, and the like. The FFM layer surface can be
printed upon using conventional water-based, solvent-base, and
ultra-violet inks, to provide a desired design and/or message. In
an example embodiment, the FFM layer is printed upon via one or
more printing station by Flexo method applying ultra-violet ink via
Anilox rolls. The total thickness of the print layer is understood
to vary depending on the number of printing stations and thickness
of ink applied at each station to create a particular design or
message. In an example embodiment, the total print thickness is
approximately 10 micrometers, applied via multiple printing
stations and multiple Anilox rolls. Ultra-violet ink is designed to
cure to form a cross linked structure that provides supplemental
reinforcement to the underlying FFM layer, thereby aiding
subsequent convertibility and dispensability.
[0068] After the faceless PSA label construction is printed or
marked it is routed for converting, where it can be converted by
conventional conversion methods, such as by die cutting and matrix
stripping. In an example embodiment, the faceless PSA label
construction is converted by die cutting and matrix stripping
methods at a web speed that is comparable to PSA label
constructions comprising conventional face stocks. In an example
embodiment, the faceless PSA construction is die cut and matrix
stripped at a web speed of approximately 150 feet per minute, and
can be die cut and matrix stripped at web speeds up to
approximately 300 feet per minute depending on a number of factors,
such as the type of FFM used, the coat weight of the FFM, the
thickness and type of ink used to print or mark the FFM layer.
Generally speaking, faceless PSA constructions comprising higher
coat weights of the FFM layer permit conversion at greater speeds
than those comprising lower coat weights of the FFM layer.
[0069] An example illustrative of faceless PSA label constructions
of this invention is as follows:
EXAMPLE--FACELESS PSA CONSTRUCTION
[0070] A faceless PSA construction was prepared by hot melt dual
die method by applying a PSA layer comprising S-246 adhesive to a
42 pound basis weight per ream Rhi-Liner 12 release liner
comprising a layer of General Electric 6000 silicone releasable
material. A FFM comprising a blend of Uni-Rez 2620 and 2623
polyamide resin (having a hot melt viscosity similar to that of the
PSA) was simultaneously applied to a surface of the PSA layer. The
coat weight of the PSA adhesive was about 20 g/m.sup.2, or about 20
micrometers thick. Five grams of Leucopure EGM UV chromophore was
added to about five gallons of the polyamide blend at a blend ratio
of one gram Leucopure per gallon resin to permit visual observation
of the FFM layer under a UV light. The polyamide resin blend
comprised about 25 percent by weight 2620 and 75 percent by weight
2623. The polyamide resin was applied at a coat weight of about 25
g/m.sup.2, or about 25 micrometers thick.
[0071] Samples of the faceless PSA construction prepared in the
example were tested for tensile strength at a web speed comparable
to that used during a die cutting and matrix stripping conversion
process, as measured crosswise across the width of the web (cross
direction). The FFM layer of the faceless PSA construction was
found to have a tensile strength of approximately 1,000 psi.
[0072] The faceless PSA construction was printed upon by Flexo
method using three printing stations and three Anilox rolls. An
ultra-violet ink was used and the total ink coating thickness was
approximately 10 micrometers. The printed faceless PSA label
construction was next converted by die cutting and matrix
stripping. A 7.5 inch (190 mm) wide web was die cut and printed two
across. The label size measured 3.25 inch (82 mm) across (cross
direction), 4.5 inch (114 mm) long (machine direction), 0.25 inch
(6 mm) center matrix between labels, and 0.43 inch (11 mm) matrix
on outside edges. The labels had a 0.18 inch (4 mm) radius, 0.125
inch (3 mm) cross direction matrix at the narrowest point, and
tapered wider to 0.31 inch (8 mm) at ends to aid in matrix
stripping. The conversion process took place at a web speed of
approximately 160 feet per minute.
[0073] The ability of the FFM layer to form, in combination with
the PSA, a sufficiently self-supporting surface is important
because it permits the faceless PSA construction to be converted,
for example by die cutting and matrix stripping methods as
discussed above, without a conventional face stock material
laminated thereto at high web speeds without matrix breaking and
the like. This feature allows the faceless PSA construction to be
converted at speeds equal or greater than that of PSA constructions
comprising a conventional face stock, while both reducing raw
material costs and increasing application flexibility.
Additionally, the use of such a FFM layer forming a sufficiently
self-supporting construction permits the converted product to be
subsequent dispensed by conventional dispensing methods.
[0074] A key feature of faceless PSA constructions prepared
according to principles of this invention is that they display
excellent nonblocking properties, thereby allowing the construction
to be placed against a contiguous backside surface of the release
liner, or any other object surface, without adhesive interference
therewith. Faceless PSA constructions of this invention have been
tested to determine minimum nonblocking parameters. An example of
the block testing that was conducted is as follows:
[0075] Block Testing--Faceless PSA Construction
[0076] A polyamide resin FFM was prepared by reacting equimolar
quantities of 1,6-hexanediamine with Hystrene 3695 dimer acid from
Humco. The resulting mixture was dissolved at about 20 percent
solids into the following solvent mixture; 25 percent by weight of
2-propanol, 25 percent by weight of 1-pentanol, and 50 percent by
weight of 2-butanol.
[0077] A 42 pound bias weight Rhi-Liner SCK stock from Rhinelander
was coated with G. E. 6000 silicone release formulation to a coat
weight of about 1 g/m.sup.2, forming a first release liner. A hot
melt PSA was coated onto the surface of the first release liner at
a coat weight of about 20 g/m.sup.2, and a second release liner of
very low release force was laminate to the exposed PSA to form a
construction consisting of PSA between the two release liners. The
construction was placed on an unwind of a pilot coater, the
laminate was unwound, and the second release liner was removed to
expose the active PSA surface.
[0078] The polyamide solution prepared above was coated directly
onto the exposed PSA surface by direct application from a smooth
steel roll in a pan fed nip. The faceless PSA construction was
dried in air floatation ovens having three zones set for about 82
C. The resultant coating was uniform and tack free, producing a
completely nonblocking faceless PSA construction. The dried coat
weight of the polyamide FFM was measured to be about four
g/m.sup.2.
[0079] Samples from the above-described faceless PSA construction
consisted of four 50 millimeter by 200 millimeter strips. The
strips were block tested on a gradient temperature hot plate
operated in the range of from about 26 C to about 115 C. A first
strip was placed on the hot plate with the FFM layer positioned
adjacent the hot plate surface and a backside surface of the first
release liner directed up. A second strip was placed on top of the
first strip with its FFM layer positioned against the backside
surface of the release liner from the first strip, i.e., with
second strip's FFM layer facing upwardly. The strips were oriented
on the gradient hot plate in their machine direction between a
temperature gradient of from about 35 C to about 85 C
[0080] A weight of about 22 kilograms was placed on a sufficient
area the FFM layer of the second strip to impose a pressure of
about 40 kPa on the combined first and second strip faceless PSA
constructions. After about 24 hours at the about 40 kPa, the
samples were removed and observed for blocking. Blocking, for
purposes of this test, is defined as the point at which the
adhesive of the second strip transfers from the release liner of
the second strip. Blocking, at a hand delamination peel rate of
about 25 millimeters/sec, was observed to occur between the two
strips at a temperature of about 70 C. The force needed to peel the
adhesive from the release liner was in the range of from about 0.8
to 1.2 grams/millimeter.
[0081] The result of such experiment demonstrates that faceless PSA
constructions of this invention are nonblocking to a minimum
temperature of at least 50 C, and in some instances to about 70 C
for 24 hours at a pressure of about 40 kPa.
[0082] If desired, faceless PSA constructions of this invention may
comprise a FFM that has been treated to provide a particular
desired effect. For example, the FFM can be tinted to provide a
colored printable surface, or can be treated to provide an opaque
or non-transparent printable surface. If such effect is desired the
FFM can be modified with agents well known in the art to produce
the same.
[0083] Although limited embodiments of faceless PSA constructions
and methods for making the same according to principles this
invention have been described herein, many modifications and
variations will be apparent to those skilled in the art.
Accordingly, it is to be understood that, within the scope of the
appended claims, faceless PSA constructions of this invention may
be prepared other than as specifically described herein.
* * * * *