U.S. patent application number 10/369019 was filed with the patent office on 2003-09-11 for media for cold image transfer.
This patent application is currently assigned to 3M Innovative Properties Company. Invention is credited to Engle, Lori P., Graham, Paul D., Kitchin, Jonathan P., Samdahl, Lisa M., Tweeten, David W..
Application Number | 20030168156 10/369019 |
Document ID | / |
Family ID | 23988250 |
Filed Date | 2003-09-11 |
United States Patent
Application |
20030168156 |
Kind Code |
A1 |
Engle, Lori P. ; et
al. |
September 11, 2003 |
Media for cold image transfer
Abstract
Image transfer media and methods of transferring images are
provided. The image transfer media comprise a sheet having a
nonporous micro-embossed surface topography comprising cavities on
one major surface of the sheet and an ink release coating on the
embossed surface, wherein said major surface has a surface energy
of about 43 dyne/centimeter or less. A method of transferring an
image to a substrate comprises the steps of (a) printing a selected
image onto an imaging surface of an image transfer medium of the
invention; (b) contacting the imaged micro-embossed surface with
the substrate using pressure; and (c) removing the micro-embossed
surface of the image transfer medium from the substrate.
Inventors: |
Engle, Lori P.; (Little
Canada, MN) ; Graham, Paul D.; (Woodbury, MN)
; Kitchin, Jonathan P.; (Austin, TX) ; Samdahl,
Lisa M.; (Woodbury, MN) ; Tweeten, David W.;
(Oakdale, MN) |
Correspondence
Address: |
3M INNOVATIVE PROPERTIES COMPANY
PO BOX 33427
ST. PAUL
MN
55133-3427
US
|
Assignee: |
3M Innovative Properties
Company
|
Family ID: |
23988250 |
Appl. No.: |
10/369019 |
Filed: |
February 19, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10369019 |
Feb 19, 2003 |
|
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09778473 |
Feb 7, 2001 |
|
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09778473 |
Feb 7, 2001 |
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09500150 |
Feb 8, 2000 |
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Current U.S.
Class: |
156/230 ;
156/277 |
Current CPC
Class: |
B41M 5/025 20130101;
B41M 5/504 20130101; B41M 5/52 20130101; B44C 1/17 20130101; Y10T
428/24802 20150115; Y10T 428/249953 20150401; D06P 5/003 20130101;
B41M 5/508 20130101; B33Y 80/00 20141201; B44C 1/1737 20130101;
B41M 5/0256 20130101; B41M 5/529 20130101; B41M 3/006 20130101 |
Class at
Publication: |
156/230 ;
156/277 |
International
Class: |
B32B 031/00 |
Claims
What is claimed is:
1. A method of transferring an image to a substrate comprising the
steps of: (a) printing a selected image onto an imaging surface of
an image transfer medium wherein the image transfer medium
comprises a sheet having a back surface and a nonporous imaging
surface having a micro-embossed surface topography comprising
micro-embossed elements on one major surface of the sheet wherein
said major surface has a surface energy of about 43 dyne/centimeter
or less; (b) contacting the imaged micro-embossed surface with the
substrate using pressure; and (c) removing the micro-embossed
surface of the image transfer medium from the substrate.
2. The method of claim 1 wherein the image is selected on a
computer.
3. The method of claim 1 wherein the image is manipulated or
modified on a computer.
4. The method of claim 3 wherein the image is manipulated by
reversing, rotating, reducing, adjusting color, removing or adding
background, removing or adding foreground, removing or adding
images, adjusting the brightness of the image, and combinations
thereof.
5. The method of claim 1 wherein the image is applied to the image
transfer medium using inkjet printing techniques.
6. The method of claim 1 wherein the substrate comprises cloth,
wood, gypsum, sheet rock, plastic, glass, metal, ceramic, painted
surfaces, paper, cardboard, or combinations thereof.
7. The method of claim 1 wherein the pressure applied to the back
of the image transfer medium is by hand, rollers, stamps, or
combination thereof.
8. The method of claim 1 wherein the image is created by printing
ink onto the micro-embossed surface.
9. The method of claim 1 wherein at least 20 percent of the ink is
transferred to the substrate as measured by color density.
10. The method of claim 1 wherein at least 50 percent of the ink is
transferred to the substrate as measured by color density.
11. The method of claim 1 wherein at least 75 percent of the ink is
transferred to the substrate as measured by color density.
12. The method of claim 1 wherein the image transfer medium has an
ink release coating on the micro-embossed surface.
13. The method of claim 1 wherein the sheet comprises
polydimethylsiloxane, fluorinated polymer, polyolefin, polyvinyl
chloride, reactive silicones, or combinations thereof.
14. The method of claim 1 wherein the sheet has two or more
layers.
15. The method of claim 1 wherein the micro-embossed elements are
cavities.
16. The method of claim 1 wherein the micro-embossed elements are
posts.
17. The method of claim 1 wherein the micro-embossed elements are a
combination of cavities and posts.
18. The method of claim 1 wherein the nonporous imaging surface of
the image transfer medium has an ink release coating thereon.
19. The method of claim 18 wherein the ink release coating
comprises fluorinated surfactants, silicone surfactants, silicones,
fluorochemicals, polymers of silicones, polymers of
fluorochemicals, and combinations thereof.
20. The method of claim 18 wherein the ink release coating is a
result of surface energy modifying additives in the sheet.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional of U.S. application Ser.
No. 09/778,473, filed on Feb. 7, 2001, which is
continuation-in-part of U.S. application Ser. No. 09/500,150, filed
Feb. 8, 2000, now abandoned.
FIELD OF THE INVENTION
[0002] The invention provides improved image transfer media and
methods for transferring ink images from the image transfer media
to a second substrate at ambient temperature.
BACKGROUND OF THE INVENTION
[0003] It is known to transfer images from the imaged medium to
another medium using an external heat source such as heated roll or
a hot iron. It is also known to transfer images from an image
medium to another medium using a process that does not require
heat. For example, PCT Publication WO 97/33752 describes a method
of transferring a digitized computer images to a second medium. The
method describes the use of an inkjet printer to print an image on
a laser transparency film, placing the imaged film onto the second
medium under pressure and then removing the transparency film. If
the transferred image was not satisfactory, the method was to be
repeated again using the same image. Although the method is capable
of producing high quality transferred images, a high-density image
could only be accomplished by repeating the process one or more
times, requiring precise registration of each transferred image. In
addition, the amount of ink that could be applied to the transfer
medium was limited by the substantially smooth laser transparency
transfer medium surface since relatively large amounts of ink on
the transfer medium were prone to smearing during handling and
transfer.
[0004] Additionally, the method required that pressure be applied
to the back of the transfer medium by burnishing, rollers, or
stamps in a substantially vertical manner.
SUMMARY OF THE INVENTION
[0005] The present invention is useful for indirect printing of an
image by printing an ink image onto an image transfer medium and
transferring the image to a second substrate without the
application of external heat. The image can be transferred using
minimal or low pressure (for example, on the back surface of the
transfer medium), and which may be applied with a finger or
hand.
[0006] In one aspect, the invention provides an image transfer
medium that comprises a sheet having an imaging surface, a
nonporous micro-embossed surface topography on the imaging surface
and an ink release coating on the micro-embossed surface. The
nonporous micro-embossed surface topography comprises
micro-embossed elements, preferably, cavities and the
micro-embossed surface has a surface energy of about 43
dyne/centimeter or less.
[0007] In another aspect, the invention provides an indirect method
for printing an ink image on a substrate. The method comprises the
steps of printing a selected image onto a nonporous imaging surface
of an image transfer medium wherein the image transfer medium
comprises a sheet having a back surface and a nonporous imaging
surface having a micro-embossed surface topography comprising
micro-embossed elements on one major surface of the sheet wherein
said major surface has a surface energy of about 43 dyne/centimeter
or less; contacting the imaged micro-embossed surface with the
substrate using pressure on the back of the image transfer medium;
and removing the micro-embossed surface of the image transfer
medium from the substrate. The method can be used to transfer
images made from inks and other materials to another substrate.
[0008] A "micro-embossed element" means a recognizable geometric
shape that either protrudes or is depressed. "Micro-embossed
capacity" means that the imaging surface is capable of receiving at
least one drop of inkjet ink within or about each micro-embossed
element on the imaging surface. A "micro-embossed" or
"microstructured" surface has a topography wherein the average
micro-embossed element pitch, that is, center to center distance
between features, is from about 1 to about 1000 micrometers and
average peak to valley distances of individual features is from
about 1 to about 100 micrometers. "Micro-embossing" means embossing
a surface and making it a micro-embossed surface. "Nonporous" means
that the integral imaging surface of the sheet is not substantially
porous to liquid inks. "Ink release coating" means a coating that
provides for the release of not only inks but other printed
materials as well. "Surface energy" as used herein is equal to the
surface tension of the highest surface tension liquid (real or
imaginary) that will completely wet a solid with a contact angle of
0 degrees, which may be determined by measuring the critical
surface tension from static contact angles of pure liquids using
the method of W. A. Zisman described in "Relation of Equilibrium
Contact Angle to Liquid and Solid Constitution", ACS Advances in
Chemistry Series #43, American Chemical Society, 1961, pages 1-51,
incorporated by reference herein.
BRIEF DESCRIPTION OF THE FIGURES
[0009] FIG. 1 shows a magnified illustrative cross sectional view
of an embodiment of the invention.
[0010] FIG. 2 shows a magnified illustrative cross sectional view
of an embodiment of the invention.
[0011] FIGS. 3 and 4 show magnified illustrative cross sectional
views of further embodiments of the invention.
[0012] FIGS. 5-17 are magnified digital images of imaged
comparative examples, imaged examples, and image transfer media of
the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0013] FIG. 1 illustrates a preferred embodiment of the present
invention: an image transfer medium 10 that is constructed of a
sheet 12 having an imaging surface characterized by a
micro-embossed image surface topography 14 of multiple wells or
cavities 16 and peaks 18 and having a coating of an ink release
material 20. The imaging surface of the sheet is nonporous as
defined above. The ink release material is used to lower the
surface energy of the micro-embossed image surface, which
facilitates ink transfer. The image transfer medium 10 is useful
for receiving an ink image and protecting the ink image from
abrasion, and then capable of transferring the ink to another
substrate. FIG. 1 also illustrates an ink drop 30 within one cavity
16 such that the outermost surfaces or peaks 18 of the
micro-embossed topography, on a macroscopic level, control
placement of the ink drop 30 before transfer.
[0014] Sheet 12 used in the image transfer medium can be made from
any polymer or combination of polymers capable of being
micro-embossed in the manner of the present invention.
[0015] The ink release coating is a coating that resides on the
micro-embossed surface. The ink release coating may be continuous
or discontinuous and is preferably continuous. The purpose or
function of the ink release coating is to lower the surface energy
of the micro-embossed surface of the image transfer medium, thereby
facilitating a more complete transfer of the ink to a second
substrate to form an image of high color density to a second
substrate. Without the ink release coating, only portions of the
image may transfer or only a top portion of the ink contained in
each cavity may transfer to the second substrate, requiring perhaps
a second ink image printed and transferred. Thus, useful ink
release coatings are those coatings that can be applied or migrate
to the micro-embossed surface of the sheet to lower the surface
energy of the portions of the cavities which ink will contact such
that at least 20 percent, preferably at least 50 percent, even more
preferably at least 75 percent of the ink is transferred as
measured by reflectance color density.
[0016] Preferred ink release coatings include compositions
comprising silicones, fluorochemicals, and polymers thereof.
Alternatively, additives may be incorporated into polymeric
materials used for sheets or surfaces of sheets that migrate to the
surface of the image transfer medium and provide a low surface
energy coating, that is, ink release coating. These additives may
be added to thermoplastic and/or thermoset resins that are extruded
and micro-embossed to form image transfer media of the invention.
Useful surface energy modifying additives include silicone
surfactants such as those available from Osi Specialties, Inc., of
Danbury, Conn., under the tradename SILWET, and fluorinated
surfactants such as those available under the tradename FLUORAD
FC-1802, etc., available from Minnesota Mining and Manufacturing
Company, St. Paul, Minn.
[0017] Preferred ink release coatings provide the micro-embossed
surface with a surface energy of about 43 dyne/centimeter or less,
preferably about 30 dyne/centimeter or less, more preferably about
25 dyne/centimeter or less. Ink release coating materials that will
provide surface energies of 43, 30, and 25 dynes/centimeter or less
are commercially available.
[0018] In general, the choice of geometrical configuration of the
specific micro-embossed features does not greatly influence image
transfer performance, so long as there is sufficient micro-embossed
capacity to control placement of an individual drop of ink. In some
preferred embodiments, the geometrical configuration is chosen such
that the micro-embossed element pitch (i.e., center to center
distance between micro-embossed elements) is less than about 340
micrometers. In further preferred embodiments, the micro-embossed
micro-embossed element density of the pattern is such that the
cavity walls actually collapse when moderate pressure is applied by
hand to effect the transfer of the image.
[0019] For example, low density polyethylene walls micro-embossed
as an orthogonal grid and having an average wall thickness of 10-25
micrometers, spaced with a micro-embossed element pitch of 338
micrometers, and having square cavities with a depth of 25
micrometers, completely collapse during image transfer with
moderate hand pressure. On the other hand, the same low density
polyethylene material micro-embossed with an orthogonal grid
pattern with walls 10-25 micrometers thick, spaced with a
micro-embossed element pitch of 127 micrometers, and having square
cavities with a depth of 25 micrometers do not collapse.
[0020] In general, the amount of ink transferred from films with
collapsible features is superior to those films containing more
rigid features. Silicone rubber micro-embossed elements are
preferred, since they collapse under pressure, but quickly recover
to their original shape when pressure is removed so the film can be
used again.
[0021] In a preferred embodiment, the micro-embossed imaging
surface topology is chosen so that ink droplets printed onto the
micro-embossed surface do not protrude above the tops of the
micro-embossed elements thereby improving handling properties of
imaged sheet.
[0022] In another embodiment, shown in FIG. 2, the image transfer
medium 40 is constructed of a sheet 42 having an micro-embossed
imaging surface topography 44 of multiple wells or cavities 46 and
peaks 48 wherein the micro-embossed or image surface has ink
release properties. In this embodiment, the micro-embossed imaging
surface itself has ink release properties, that is, the
micro-embossed surface has a surface energy that facilitates the
transfer of ink from the surface topography without any additional
ink release coating added (See FIG. 1). The imaging surface of the
sheet is also nonporous as defined above.
[0023] Materials having a surface energy in the range of from about
43 dyne/centimeter or less are suitable for use as sheets 42 or as
a micro-embossed surface topography 44. Non-limiting examples of
materials that provide a suitable surface energy include polymeric
materials such as polydimethylsiloxanes, fluorinated polymers,
polyolefins (e.g., such as polyethylene, polypropylene, etc.) and
polyvinyl chloride. For use with aqueous inks, useful materials
have a surface energy of less than about 43 dyne/centimeter, with
materials having a surface energy of from about 30 dyne/centimeter
or less being preferred. For use with non-aqueous inks (i.e.,
solvent based or. 100 percent solids), materials having a surface
energy of from about 30 dyne/centimeter or less are useful,
preferably from about 25 dyne/centimeter or less.
[0024] In another embodiment, shown in FIG. 3, the image transfer
medium 50 is constructed of a sheet 52 having a micro-embossed
imaging surface topography 54 of multiple posts 56. The posts may
be any protruding geometric shape, for example, circular, oval,
trapezoidal, spiral, square, triangular, octagonal, and the like.
Preferably, the space between posts is from about 10 to about 1000
micrometers, even more preferably from about 50 to about 800
micrometers and even more preferably from about 200 to about 600
micrometers. Preferably, the height of the posts ranges from about
5 to about 100 micrometers, more preferably from about 10 to about
70 micrometers, even more preferably from about 10 to about 40
micrometers. Preferably, the diameter of the posts ranges from
about 10 to about 150 micrometers, more preferably from about 10 to
about 100 micrometers and even more preferably from about 30 to
about 90 micrometers. Preferably, the density of the posts ranges
from about 1 to about 40 posts per square millimeter, more
preferably from about 2 to about 20 posts per square millimeter and
even more preferably from about 2 to about 10 posts per square
millimeter. As shown above sheet 52 may be made from a material
that provides an ink release property to the imaging surface.
Alternatively, an ink release coating may be coated onto the
imaging surface.
[0025] In another embodiment shown in FIG. 4, the image transfer
medium 60 is constructed of a sheet 62 having a micro-embossed
imaging surface topography 64 of wells or cavities 66 and posts 68.
The cavities are spaced such that they provide control over the
placement of the ink droplets while the posts are spaced to prevent
accidental smearing of the wet ink. Preferably, the pitch of the
cavities is finer than the pitch of the posts. However, the pitch
of the cavities when combined with the posts can typically be wider
than the pitch of cavities alone since the posts prevent the wet
image from smearing during handling. The posts may also be applied
in a random manner to an imaging substrate having cavities such
that some of the posts are within a cavity. The height of the posts
may or may not exceed the height of the walls of the cavities. As
described above, the imaging surface may be constructed of a
material that provides an ink release property of the imaging
surface may be coated with an ink release coating.
[0026] The sheets described in FIGS. 1-4 can be a solid film. The
sheets may be transparent or translucent, clear or tinted, or
optically transmissive. The sheets 12 and 42 are preferably
transparent.
[0027] Nonlimiting examples of polymeric films useful as sheets in
the present invention include thermoplastics such as polyolefins
(for example, polyethylene, polypropylene, polybutylene, copolymers
of styrene and butadiene, copolymers of ethylene and propylene,
etc.); poly(vinyl chloride); hydrolyzed or unhydrolyzed copolymers
of ethylene with vinyl acetate; polycarbonates; norbornene
copolymers; fluorinated thermoplastics such as copolymers and
terpolymers comprising hexafluoropropylene, vinylidene fluoride,
tetrafluoroethylene, or vinyl fluoride, and surface modified
versions thereof, poly(ethylene terephthalate) and copolymers
thereof, polyurethanes, polyimides, acrylics, and filled versions
of the above using fillers such as silicates, aluminates, feldspar,
talc, calcium carbonate, titanium dioxide, and the like. Also
useful in the application are non-wovens, coextruded films, and
laminated films made from the materials listed above. A person of
ordinary skill in the art can easily measure the surface energy of
any of the above films to determine whether the films provide a
suitable surface energy for use in an image transfer media
described by FIG. 2 and the accompanying text.
[0028] More specifically, polyolefins can be ethylene homopolymers
or copolymers, such as "7C50" brand ethylene propylene copolymer
commercially available from Union Carbide Co. of Houston, Tex.
Other specifically useful films include "LEXAN" polycarbonate from
General Electric Plastics of Pittsfield, Mass., "ZEONEX" polymer
from B. F. Goodrich of Richfield, Ohio, fluoropolymers such as
"THV-500" and "THV 250" polymers from Dyneon LLC of Oakdale, Minn.,
plasticized poly(vinyl chloride), poly(ethylene terephthalate)
copolymer "EASTAR" 6763 from Eastman Chemical Co. of Kingsport,
Tenn., "AFFINITY" PL 1845 from Dow Chemical Co. of Midland, Mich.,
and SURLYN.TM. acrylic acid copolymers from E. I. Du Pont de
Nemours and Co. of Wilmington, Del.
[0029] In further embodiments of sheets shown in FIGS. 1-4, any
sheet suitable for feeding into an inkjet printer may be further
coated, laminated, or co-extruded with one or more of the polymers
suitable for use in polymeric films of according to the invention
and further micro-embossed (and, if necessary, coated with an ink
release material as described herein) to provide image transfer
media of the invention. Non-limiting examples of such sheets are
papers, including for example xerographic grade papers, specialty
inkjet papers, and coated papers, etc.; nonwoven materials,
including for example spunbond polyolefins, etc.; card stock;
envelopes; etc.
[0030] Thermoset materials are also additionally useful as
materials for sheets or micro-embossed imaging surface topographies
that have ink release properties without the use of an ink release
coating. For example, reactive silicones (either two-part or
moisture curable, UV-curable materials (e.g., acrylate mixtures)
may be applied to a micro-embossed roll, cured and removed from the
roll to give an micro-embossed film having an inverse image of the
roll.
[0031] The structure of the micro-embossed surface topography can
be any structure that provides cavities that will each hold at
least 10 pL of ink. For example, the topographies for the cavities
can range from the extreme of cubic cavities with parallel
vertical, planar walls, to the extreme of hemispherical cavities,
with any possible solid geometrical configuration of walls in
between the two extremes. Specific examples include conical
cavities with angular, planar walls, truncated pyramid cavities
with angular, planar walls, and cube comer shaped cavities. Other
useful micro-embossed structures are described in PCT publications
WO 00/73082 and WO 00/73083, incorporated by reference herein for
the micro-embossed structures and methods of making micro-embossed
substrates.
[0032] The pattern of the topography can be regular, random, or a
combination of the two. "Regular" means that the embossing pattern
is planned and reproducible regardless of the pattern of the
embossing. "Random" means one or more features of the
micro-embossed elements are intentionally and/or systematically
varied in a non-regular manner. Examples of features that are
varied include for example, micro-embossed element pitch,
peak-to-valley distance, depth, height, wall angle, edge radius,
and the like. Combination patterns may for example comprise
patterns that are random over an area having a minimum radius of
ten cavity widths from any point, but these random patterns can be
reproduced over larger distances within the overall pattern.
[0033] More than one drop of ink may be contained in a cavity
because the mixing of the colors cyan, yellow, and magenta are
required to create the infinite number of colors demanded in the
inkjet industry. Thus, the volume of the cavities should be capable
of holding as many as three drops of different colors of ink. The
volume of a cavity can range from about 1 to about 20,000 pL,
preferably from about 1 to about 10,000 pL, more preferably from
about 3 to about 1,000 pL, even more preferably from about 30 to
about 10,000 pL, and even more preferably from about 300 to about
10,000 pL.
[0034] For applications in which desktop inkjet printers (typical
drop size of 3-20 pL) will be used to generate the image, cavity
volumes of from about 1000 to about 3000 pL are preferred. For
applications in which large format desktop inkjet printers (typical
drop size of 10-200 pL) will be used to generate the image, cavity
volumes of from about 3,000 to about 10,000 pL are preferred.
[0035] Another way to characterize the structure of the cavities is
to describe the cavities in terms of aspect ratios. An "aspect
ratio" is the ratio of the depth to the width of the cavity. Useful
aspect ratios range from about 0.01 to about 2, preferably from
about 0.05 to about 1, and more preferably from about 0.05 to about
0.3.
[0036] The overall depth of the cavities depends on the shape,
aspect ratio, and desired volume of the cavities. For a
cubic-shaped cavity, the depth ranges from about 5 to about 100
micrometers. For a hemispherical-shaped cavity, the depth ranges
from about 7 to about 100 micrometers. The depths of other
geometrically shaped cavities reside in between these two extremes
for a given volume.
[0037] Micro-embossed element pitch of the micro-embossed image
transfer media of the invention are in the range of from 1 to about
1000 micrometers, preferably from 10 to about 500 micrometers, more
preferably from about 50 to about 400 micrometers. It is recognized
that in some embodiments of the invention, it may not be necessary,
or desirable, that uniform micro-embossed element pitch be observed
between micro-embossed elements, nor that all features be
identical. Thus, an assortment of different types of features, for
example, cavities or wells with, perhaps, an assortment of
micro-embossed element pitches may comprise the micro-embossed
surface of the image transfer media according to the invention.
[0038] Image transfer media of the invention may be prepared and
used in many dimensions. Useful lengths may be from about 1
centimeter up to 2,000 meters or even longer (especially when used
in roll form). Useful widths may be from about 0.5 centimeter up to
about 250 centimeters or even wider. Useful thicknesses of image
transfer media of the invention may range from about 25 micrometers
up to 0.5 millimeter or even higher so long as the material may be
printed by inkjet means.
[0039] The image transfer media of the invention may also
optionally have an ink receptive coating on the micro-embossed
imaging surface. The ink receptive coating may comprise one or more
layers. The purpose of the ink receptive coating is to limit
migration of colorant both prior to and after subsequent image
transfer. The ink receptive coating may be used on any image
transfer media described in this application.
[0040] Useful ink receptive coatings are hydrophilic and aqueous
ink sorptive. Such coatings include, but are not limited to,
polyvinyl pyrrolidone, homopolymers and copolymers and substituted
derivatives thereof; vinyl acetate copolymers, for example,
copolymers of vinyl pyrrolidone and vinyl acetate, copolymers of
vinyl acetate and acrylic acid, and the like, and hydrolyzed
derivatives thereof; polyvinyl alcohol, acrylic acid homopolymers
and copolymers; co-polyesters such as the VITEL co-polyesters
including VITEL-2700B co-polyester available from Bostick,
Middleton, Mass.; acrylamide homopolymers and copolymers;
cellulosic polymers; styrene copolymers with allyl alcohol, acrylic
acid, and/or maleic acid or esters thereof; alkylene oxide polymers
and copolymers; gelatins and modified gelatins; polysaccharides,
and the like, as disclosed in U.S. Pat. Nos. 5,766398; 4,775,594;
5,126,195; and 5,198,306. Vinyl pyrrolidone homopolymers and
copolymers are preferred.
[0041] Optionally, the ink receptive coatings may also include
additives that provide a visual property to the transferred image.
Such additives include glitter, glass bubbles, pigments, mica, UV
absorbers and stabilizers, etc.
[0042] Additionally, the image transfer media of the invention may
also have one or more surfactants coated onto the micro-embossed
imaging surface. Examples of useful surfactants include those
described in U.S. Pat. No. 5,932,355 at column 7, lines 22-31,
incorporated by reference in this application.
[0043] The transfer medium 10 optionally has an adhesive layer on
the major surface of the sheet opposite micro-embossed image
surface 12 that is also optionally but preferably protected by a
release liner. After imaging, the receptor medium 10 can be adhered
to a rigid substrate before image transfer.
[0044] The choice of adhesive and release liner depends on usage
desired for the image graphic.
[0045] Pressure-sensitive adhesives can be any conventional
pressure-sensitive adhesive that adheres to both the polymer sheet
and to the surface of the item upon which the transfer medium
having the precise image is to be placed. Pressure-sensitive
adhesives are generally described in Satas, Ed., Handbook of
Pressure Sensitive Adhesives 2nd Ed. (Von Nostrand Reinhold 1989),
the disclosure of which is incorporated by reference.
Pressure-sensitive adhesives are commercially available from a
number of sources. Particularly preferred are acrylate
pressure-sensitive adhesives commercially available from Minnesota
Mining and Manufacturing Company, and generally described in U.S.
Pat. Nos. 5,141,790; 4,605,592; 5,045,386; and 5,229,207; and EPO
Patent Publication EP 0 570 515 B1.
[0046] Release liners are also well known and commercially
available from a number of sources. Nonlimiting examples of release
liners include silicone coated kraft paper, silicone coated
polyethylene coated paper, silicone coated or non-coated polymeric
materials such as polyethylene or polypropylene, as well as the
aforementioned base materials coated with polymeric release agents
such as silicone urea, fluorinated polymers, urethanes, and long
chain alkyl acrylates, such as defined in U.S. Pat. Nos. 3,957,724;
4,567,073; 4,313,988; 3,997,702; 4,614,667; 5,202,190; and
5,290,615; the disclosures of which are incorporated by reference
herein and those liners commercially available as POLYSLIK brand
liners from Rexam Release of Oakbrook, Ill., and EXHERE brand
liners from P. H. Glatfelter Company of Spring Grove, Pa.
[0047] Method of Forming Micro-Embossed Image Surface
[0048] The micro-embossed imaging surface can be made from any
contacting technique such as casting, coating, or compressing
techniques. More particularly, micro-embossing can be achieved by
at least any of (1) casting a molten thermoplastic using a tool
having a pattern, (2) coating of a fluid onto a tool having a
pattern, solidifying the fluid, and removing the resulting
micro-embossed solid, or (3) passing a thermoplastic film through a
nip roll to compress against a tool having that micro-embossed
pattern. Desired embossing topography can be formed in tools via
any of a number of techniques well-known to those skilled in the
art, selected depending in part upon the tool material and features
of the desired topography. Illustrative techniques include etching
(e.g., via chemical etching, mechanical etching, or other ablative
means such as laser ablation or reactive ion etching, etc.),
photolithography, stereolithography, micromachining, knurling
(e.g., cutting knurling or acid enhanced knurling), scoring or
cutting, etc.
[0049] Alternative methods of forming the micro-embossed image
surface include thermoplastic extrusion, curable fluid coating
methods, and embossing thermoplastic layers which can also be
cured.
[0050] Compressing Method
[0051] This method uses a hot press familiar to those skilled in
the art of compression molding.
[0052] The pressure exerted in the press typically ranges from
about 48 kPa to about 2400 kPa.
[0053] The temperature of the press at the mold surface typically
ranges from about 100.degree. C. to about 200.degree. C. and
preferably from about 110.degree. C. to about 150.degree. C.
[0054] The dwell time of pressure and temperature in the press
typically ranges from about 1 to about 5 minutes. The pressure,
temperature and dwell time used depend primarily on the particular
material being micro-embossed, as is well known to those skilled in
the art. The process conditions should be sufficient to cause the
material to flow and faithfully take the shape of the surface of
the tool being used. Any generally available commercial hot press
may be used, such as Wabash Model 20-122TM2WCB press from Wabash
MPI of Wabash, Ind.
[0055] Extrusion Method
[0056] A typical extrusion process for the present invention
involves passing an extruded material or preformed substrate
through a nip created by a chilled roll and a casting roll having a
surface having a random pattern inverse of desired micro-embossed
image surface, with the two rolls rotating in opposite
directions.
[0057] Single screw or twin screw extruders can be used. Conditions
are chosen to meet the general requirements which are understood to
the skilled artisan. Representative but non-limiting conditions are
outlined below.
[0058] The temperature profile in the extruder can range from
100.degree. C. to 250.degree. C. depending on the melt
characteristics of the resin.
[0059] The temperature at the die ranges from 150.degree. C. to
230.degree. C. depending on the melt strength of the resin.
[0060] The pressure exerted in the nip can range from about 140 to
about 1380 kPa and preferably from about 350 to about 550 kPa.
[0061] The temperature of the nip roll can range from about
5.degree. C. to about 150.degree. C. and preferably from about
10.degree. C. to about 100.degree. C., and the temperature of the
cast roll can range from about 25.degree. C. to about 100.degree.
C. and preferably about 40.degree. C. to about 60.degree. C.
[0062] The speed of movement through the nip typically ranges from
about 0.25 to about 10 m/min and preferably as fast as conditions
allow.
[0063] Nonlimiting examples of equipment useful for this extrusion
method include single screw extruders such as a 1{fraction (1/4)}
inch KILLION extruder, available from Killion Extruders, Inc. of
Cedar Grove, N.J., equipped with a gear pump such as a ZENITH gear
pump, available from Parker Hannifin Corp., Zenith Pumps Division
of Sanford, N.C., to control flow rate; co-rotating twin screw
extruders such as a 25 millimeters BERSTORFF extruder, available
from Berstorff Corporation of Florence, Ky.; and counter-rotating
twin screw extruders such as a 30 millimeters LEISTRITZ extruder,
available from American Leistritz Extruder Corporation of
Somerville, N.J. Flow rate in the twin screw extruder can be
controlled using weight loss feeders such as a K-TRON extruder,
available from K-tron America of Pitman, N.J., to feed the raw
material into the extruder. A film die with adjustable slot is used
to form a uniform film out of the extruder.
[0064] Calendering may be accomplished in a continuous process
using a nip, as is well known in the film handling arts. In the
present invention, a web having a suitable embossable thermoplastic
exposed layer, and having sufficient thickness to receive the
desired pattern is passed through a nip formed by two cylindrical
rolls, one of which has an inverse image to the desired embossing
engraved into its surface. The embossable thermoplastic exposed
layer must contact the engraved roll at the nip. Sufficient heating
to temperatures of from 100.degree. C. up to 540.degree. C. of the
web so that embossing may occur may be supplied to the web prior to
reaching the nip by radiant heat sources (e.g., heat lamps,
infrared heaters, etc.) and/or by use of heated rolls at the nip. A
combination of heat and pressure at the nip (typically, 100 to 500
lb/inch (1.8 kg/centimeter to 9 kg/centimeter)) is generally used
in the practice of the present invention.
[0065] The image transfer media of the invention are useful for
receiving an ink image and then transferring that image to another
substrate. The transfer of the image is a "cold transfer" in that
no external heat is required to transfer the image and the image is
transferred at ambient temperature. Generally, an image is printed
onto the micro-embossed surface of the image transfer media. The
image transfer media is then applied to a second substrate, image
side down, and pressure is applied to the back of the image
transfer medium such that the ink image is transferred to the
second substrate. Then the image transfer medium is removed from
the second substrate.
[0066] The image to be transferred is first preferably selected on
a computer. After the image is selected, the image is manipulated
or modified as desired on the computer. Examples of image
manipulation include reversing, rotating, reducing, distorting,
adjusting color, removing or adding background, removing or adding
foreground, removing or adding images, and adjusting the brightness
of the image. Then the image is printed onto the image transfer
medium of the invention.
[0067] The image is preferably applied to the image transfer medium
using inkjet printing techniques. Nonlimiting commercially
available examples include thermal inkjet printers such as DESKJET
brand, PAINTJET brand, DESKWRITER brand, DESIGNJET brand, and other
printers commercially available from Hewlett Packard Corporation of
Palo Alto, Calif., and the NovaJet brand wide format printers
commercially available from Encad, Inc., of San Diego, Calif. Also
included are piezo type inkjet printers such as those from
Seiko-Epson, Raster Graphics, and Xerox, spray jet printers and
continuous inkjet printers. Any of these commercially available
printing techniques introduce the ink in a jet spray of a specific
image into the medium of the present invention. Any of the above
printers can be attached to a computer so to print computer
generated images.
[0068] The image transfer media of the invention can be used with a
variety of inkjet inks obtainable from many commercial sources. It
should be understood that each of these inks has a different
formulation, even for different colors within the same ink family.
Nonlimiting sources include Minnesota Mining and Manufacturing
Company, Encad Corporation, Hewlett Packard Corporation, NuKote,
and the like. These inks are preferably designed to work with the
inkjet printers described above, although the specifications of the
printers and the inks will have to be reviewed for appropriate drop
volumes and dote per inch (dpi) in order to further refine the
usefulness of the present invention.
[0069] Once the image has been printed onto the transfer medium,
the image can be transferred to a second medium. The image may be
transferred to any substrate capable of receiving the ink image.
Specific examples include cloth, wood, gypsum or sheet rock (either
painted or unpainted), plastics, glass, for example windows,
metals, ceramics, stone, painted surfaces such as walls, paper,
cardboard, and the like. Once the image transfer medium is placed
onto the second substrate, pressure is applied to the back of the
transfer medium. The pressure is preferably applied by hand, but
may be applied using rollers, stamps, or any other means of
applying substantially vertical pressure to the back of the
transfer medium. After sufficient pressure has been applied to the
back of the transfer medium, the transfer medium is removed from
the second substrate and the image transfer has been completed.
[0070] Image transfer media of the present invention can also be
employed with other jettable materials, i.e., those materials
capable of passing through an inkjet printing head. Nonlimiting
examples of jettable materials include adhesives, biological
fluids, chemical assay reagents, pharmaceuticals, particulate
dispersions, waxes, and combinations thereof.
[0071] Image transfer media of the present invention can also be
employed with non-jettable materials so long as an inkjet printing
head is not needed to deposit the material on the micro-embossed
surface. For example, U.S. Pat. No. 5,658,802 (Hayes et al.)
discloses printed arrays for DNA, immunoassay reagents or the like
using arrays of electromechanical dispensers to form extremely
small drops of fluid and locate them precisely on substrate
surfaces in miniature arrays.
EXAMPLES
[0072] "TESLIN" is a trade designation for silica-filled high
density polyethylene having very small pore sizes (typically
0.02-0.5 micrometers), available from PPG Industries of Pittsburgh,
Pa.
[0073] "HP-870C", "HP855Cse", "HP680C", and "HP2000C" are trade
designations for desktop thermal inkjet printers, and "HP GLOSSY
PAPER" is a trade designation for a thermal inkjet printer paper,
all available from Hewlett-Packard Corp.
[0074] "HP51645A" and "HP51641A" inks were used with "HP-870C"
printer; "HP51641A" and "HP51645A" inks were used with "HP855Cse"
printer; "HP51649A" and "HP51641A" inks were used with "HP680C"
printers; and "HP Part No. 10" ink was used with "HP2000C"
printer.
[0075] 7C50 is a trade designation for ethylene-propylene
copolymer, available from the Union Carbide Corp.
[0076] "THV FLUOROPOLYMER THV-200" is a trade designation for
fluorinated polymer film, available from Dyneon, LLC.
[0077] "PETG" copolyester film is available from Eastman
Chemical.
[0078] "SCOTCHCAL WHITE GRAPHIC MARKING FILM" is a trade
designation for PVC film, available from the Minnesota Mining and
Manufacturing Company.
[0079] "3M FINE GRADE SANDING SPONGE" was obtained from Minnesota
Mining and Manufacturing Company.
[0080] "PVP/VA S-630" is a trade designation for a powdered form of
poly(vinylpyrrolidone-co-vinyl acetate); VIVIPRINT 111 is a trade
designation for a 10 weight percent solids hydrophilic acrylic
polymer in water having amine functionality, both are available
from International Specialty Products of Wayne, N.J.
[0081] Mayer Rods (i.e., wire-wound rods) are available from R D
Specialties, Inc. of Webster, N.Y.
[0082] "SILICONE SPRAY MOLD RELEASE" is a trade designation for a
silicone spray release agent, available from IMS Company, Inc. of
Chagrin Falls, Ohio.
[0083] "SILASTIC J" and "SILASTIC E" are trade designations for
curable RTV silicone elastomers, available from Dow Coming Co. of
Midland, Mich.
[0084] "MICROPRINT MULTI-SYSTEM" paper and Xerographic grade paper
(20 lb. paper) are available from Georgia Pacific Corp.
[0085] Silicone coated LDPE/PET/HDPE (i.e., low density
polyethylene/polyethylene terephthalate/high density polyethylene)
film surface and polyethylene coated paper each having a thin
silicone topcoat on the LDPE surface, are available from Rexam
Release.
[0086] "GRETAG SPM 55 REFLECTANCE DENSITOMETER" is available from
Gretag-Macbeth of Gastonia, N.C.
[0087] "LEXMARK Z11" is a trade designation for a thermal inkjet
printer, available from Lexmark International of Lexington, Ky. Ink
used with this printer was Lexmark Part No. 12A1980.
[0088] "EPSON STYLUS COLOR" is a trade designation for a thermal
inkjet printer, available from US Epson, Inc. of Torrance, Calif.
Ink used with this printer was Epson Part Nos. S020034 and
S020036.
[0089] The 100 percent cotton T-shirt cloth used in the examples
was "HANES SPECIAL-TEE BRAND", 100 percent combed cotton (white),
available from Hanes Companies of Winston Salem, N.C. and had a
thickness of 0.203 millimeter and basis weight of 104
g/m.sup.2.
[0090] "NAFION SE-20092" is a trade designation for perfluorinated
vinyl ether having sulfonic acid functionality/tetrafluoroethylene
copolymer as a 20 weight percent solids in
ethanol/isopropanol/water, available from E. I. du Pont de Nemours
Co.
[0091] "ASPEN SELECT GRADE HOBBY WOOD" is a trade designation for
aspen, which has been sanded smooth for use by hobbyists and it or
equivalents may be obtained at hobby and craft stores.
[0092] "DISPAL 23N4-20" and "DISPAL 11N7-12" are trade designations
for an aqueous alumina dispersion, available from Vista Chemical
Co. of Houston, Tex.
[0093] "FREESOFT 970" is a trade designation for an aqueous
silicone polymer emulsion (20 weight percent solids), available
from B. F. Goodrich Co.
[0094] "WYP-ALL" is a trade designation for heavy-duty paper
wipers, available from Scott Paper Co. of Van Nuys, Calif.
[0095] Isopropanol and denatured ethanol were obtained from E.M.
Science of Gibbstown, N.J.
[0096] "VITEL-2700B" is a trade designation for a co-polyester,
available from Bostick, Middleton, Mass.
[0097] "AIRFLEX 460" is a trade designation for a 63 weight percent
solids in water vinyl acetate-ethylene copolymer emulsion available
from Air Products and Chemicals of Allentown, Pa.
[0098] Ink transfer was calculated by measuring color density of
the imaged ink transfer medium before and after transfer using a
Gretag SPM 55 REFLECTANCE DENSITOMETER. Percent ink transfer was
calculated according to the following equation:
Percent ink transfer=(reflective optical density of material
receiving image)/(reflective optical density of material receiving
image)+(reflective optical density of remainder on transfer
sheet).times.100 percent.
[0099] The following patterns were used in many of the examples,
which follow and are referred to as Pattern 1 and Pattern 2. Both
patterns were micro-embossed by calendering of a continuous web of
the materials to be micro-embossed using a corresponding engraved
roll having an inverse image as the roll contacting the
micro-embossed side of the web, unless otherwise specified.
[0100] Pattern 1 is a "75 LPI" pattern referred to in the examples
as an array of square cavities that are 25 micrometers deep and
having a micro-embossed element pitch of 332 micrometers and walls
that are 9 micrometers thick at their top and 22 micrometers thick
at their base.
[0101] Pattern 2 is a "130 LPI" pattern of square cavities of 197
micrometers micro-embossed element pitch, cavity depth of 15
micrometers, and included wall angle of 60.degree.. The wall
thickness is 20 micrometers at the bottom of the cavity.
Additionally, at the center of the bottom of this cavity resides a
second cavity that increases the total volume of the structure.
This second cavity is pyramid shaped (four sides proceeding to a
point at the deepest point of the two-cavity structure). It is 38
micrometers wide at the opening, and is 10 micrometers deep with a
125.degree. included angle of descent.
Example 1
[0102] A solution was prepared by diluting 2 parts NAFION SE-20092
(perfluorinated vinyl ether having sulfonic acid
functionality/tetrafluor- oethylene copolymer as a 20 weight
percent solids in ethanol/isopropanol/water) with a solution
consisting of 10 parts ethanol, 5 parts isopropanol, 1 part water.
This solution was coated with a #4 Mayer Rod (0.0091 millimeter
nominal wet thickness) onto silicone coated LDPE/PET/HDPE film
having Pattern 2 micro-embossed thereon and dried for 15 minutes in
an oven at 70.degree. C.
[0103] The coated film was imaged with a test pattern of solid
block colors and lines contained in the blocks using an EPSON
STYLUS COLOR inkjet printer operating in 720 dpi mode and using the
recommended aqueous inks (i.e., the black ink cartridge was Epson
Part No. S020034, and the color ink cartridge was Epson Part No.
S020036). The film was individually applied to MICROPRINT
MULTI-SYSTEM paper so as to contact the ink image with the paper.
Moderate hand pressure was applied to the unimaged side of the film
so to effect transfer of the image to the paper, and the film was
subsequently removed.
[0104] The image transferred from this micro-embossed film had very
good image quality characterized by sharp edges, good color
density, and color uniformity.
Comparative Example 1
[0105] Black pigmented solvent borne ink (3M Commercial Graphics
Division Ink #3700 series) was jetted directly onto plain aluminum
panels using 1.4 centimeters high boldface type to form the
characters "3M" using a piezoelectric printhead (MIT) equipped with
128 nozzles, available from Modular Ink Technology of Stockholm,
Sweden, jetting 70 pL drops at 195.times.195 dpi and then dried at
ambient temperature for about 30 minutes. The resultant magnified
printed image is shown in FIG. 5.
Comparative Example 2
[0106] An unembossed sheet of fluoropolymer film (THV 200 film) was
printed as described in Comparative Example 1. The imaged side of
film was immediately applied to an aluminum panel, and the unimaged
side of the film was rolled 3-4 times with firm hand pressure using
a rubber roller. The film was removed, leaving behind an imaged
aluminum panel shown in FIG. 6 in magnified form.
Example 2
[0107] A crosslinked silicone mold (SILASTIC J) having an inverse
image of the resulting pattern was compression molded against a
sheet of fluoropolymer film (THV 200 film) to micro-emboss a
pattern of cavities 25 micrometers deep and 250 micrometers from
center to center, with walls 25 micrometers thick at the base of
the wall and a 15.degree. included wall angle, onto the substrate;
the structure was confirmed in each case using standard
interferometry techniques. The imaged side of the micro-embossed
film was printed as described in Comparative Example 1, and
immediately applied to an aluminum panel and the backside of the
film was rolled 3-4 times with firm hand pressure using a rubber
roller. The film was removed, leaving behind an imaged aluminum
panel shown in FIG. 7 in magnified form.
[0108] FIGS. 6-7 clearly show that the micro-embossed film was much
more effective at transferring an ink image to a substrate than was
a flat film.
[0109] FIGS. 5 and 7 show that image quality of the transferred
image approaches that of direct printing.
[0110] Examples 3a and 3b show the improvement in image quality
observed when a fabric substrate is dampened prior to image
transfer.
Example 3a
[0111] An array of 25 micrometer deep truncated square pyramidal
cavities that had a micro-embossed element pitch of 50 micrometers
were micro-embossed into a piece of PETG film. The micro-embossed
pattern was made by compression molding a PETG film with heating
against a SILASTIC J master having the inverse pattern. The
cavities were surrounded by walls that were 4 micrometers thick at
their tops and 16 micrometers thick at their base. A thin layer of
SILICONE SPRAY MOLD RELEASE was applied to the micro-embossed
surface of this film using a spray bottle. The micro-embossed
surface was then imaged using an HP855Cse ink jet printer with the
print driver set to the best quality setting (i.e., HP Glossy Paper
Media Setting). The imaged surface of the transfer film was
intimately contacted with a dry 100 percent cotton cloth and
moderated pressure was applied to the backside of the transfer film
to effect transfer of the image to the cotton fabric.
Example 3b
[0112] The exact procedure described in Example 3a was repeated,
except the 100 percent cotton cloth was moistened with deionized
water and wrung out by hand prior to transfer of the wet ink image.
The moistened cotton cloth contained approximately 118 grams of
water per square meter.
[0113] Table 1 shows data on the percentage of ink transferred for
both of the aforementioned examples. Reflected color density
measurements used to calculate the percent ink transfer were made
using a Gretag SPM 55 REFLECTANCE DENSITOMETER.
1 TABLE 1 Percent Ink Transfer Substrate Black Magenta Cyan Yellow
Example 3a 27 74 75 75 (Dry Cotton) Example 3b 90 98 98 97 (Damp
cotton)
Example 4
[0114] Silicone treated polyethylene coated paper was
micro-embossed with a pattern of square cavities by compression
molding the film against a nickel plate whose surface consisted of
a square grid of intersecting 25.4 micrometer deep grooves. The
grooves in the plate were spaced with a micro-embossed element
pitch of 79 lines per centimeter and were nominally 25.4
micrometers wide.
[0115] A Hewlett-Packard HP-870C desktop ink jet printer was used
to image the films with a pattern that included square regions of
black and each of the three secondary colors (using paper mode,
best quality settings). The imaged surface of the film was
intimately contacted with a 100 percent cotton fabric and moderate
finger pressure was applied to the unimaged film surface to effect
transfer of the image to the fabric.
Example 5
[0116] A micro-embossed silicone rubber film was produced by
applying a 0.41 millimeter thick coating of SILASTIC E silicone
rubber material with a knife coater to the nickel plate of Example
4. The freshly applied SILASTIC E silicone rubber material was
degassed in a vacuum oven for approximately one hour and allowed to
cure fully while still covering the nickel plates. The cured film
was then carefully removed from the nickel plates. The film was
imaged and the image transferred to cotton as in Example 4.
[0117] Images produced using the silicone rubber film of Example 5
were superior in terms of their image density and color uniformity,
to those produced in Example 4. Table 2 compares the transferred
color density of Example 4 to that of Example 5.
[0118] The image densities shown in Table 2 were measured using a
GRETAG SPM 55 densitometer. For the secondary colors, the two
entries in each cell represent the CMYK components that are the
most intense for each color.
[0119] All images were of acceptable quality, but images resulting
from use of the flexible silicone elastomer film of Example 5 were
even better than those of Example 4.
2TABLE 2 Transfer Substrate Black Red (M, Y) Green (C, Y) Blue (C,
M) Example 4 0.42 0.52, 0.52 0.53, 0.50 0.55, 0.44 Example 5 1.18
0.78, 0.79 0.8, 0.69 0.66, 0.85
Example 6
[0120] Silicone treated polyethylene coated paper sheets,
micro-embossed with Pattern 1, were printed with a LEXMARK Z11
inkjet printer (tricolor ink cartridge, Lexmark Part No. 12A1980,
settings for high resolution print quality), and successfully used
to transfer ink images to the following surfaces as described in
Example 4 above: paper mache gift box, cotton T-shirt, polystyrene
foam, pine wooden picture frame surface, TESLIN film, and painted
drywall surface.
Example 7
[0121] This example illustrates the effect of microstructure on
image transfer quality.
[0122] Polyethylene coated paper having a thin silicone topcoat was
embossed by pressing it against a nickel plate with an orthogonal
grid of intersecting grooves in a compression molding apparatus.
The grooves in the plate were 25.4 micrometers deep, nominally 10
micrometers wide and spaced with a micro-embossed element pitch of
29.5 lines per centimeter. Embossed film samples with various
cavity depths were produced by systematically varying the residence
time of each of the film samples in the compression molding
apparatus.
[0123] After removal from the compression molding apparatus, this
resultant film (micro-embossed with the inverse image of the nickel
plate) was used as the image transfer film. An image containing
coverages of 60 percent and 100 percent solid blocks of color, as
well as resolution lines in blocks of color, was printed using a
Hewlett-Packard HP855Cse printer (black ink cartridge was
Hewlett-Packard Part No. 51645A, tricolor ink cartridge was
Hewlett-Packard Part No. 51641A, HP Glossy Paper media setting).
The wet image was transferred to plain xerographic paper. Results
are shown in Table 3.
3TABLE 3 Compression Molding Depth Of Conditions Pattern Lines/
(Temperature/ (Micrometers) Centimeter Pressure/Time) Results 5-6
30 110.degree. C./114 kPas/ Blotchy micrometers 1 min. transfers,
Poor resolution 10-12 30 110.degree. C./114 kPas Fair transfer
micrometers 110.degree. C./2 min. in colors: best for primary, 60
percent coverage, loss of resolution 23 30 110.degree. C./114 kPas
Good transfer, micrometers 110.degree. C./4 min. except for black,
which was fair 25 30 110.degree. C./114 kPas Good transfer,
micrometers 110.degree. C./5 min. except for black, which was
fair
Example 8
[0124] This example shows the effect on transfer image quality of
letting the wet ink image stay on the image transfer film for
various times.
[0125] A truncated pyramidal pattern having the micro-embossed
pattern of Example 3a was micro-embossed into PETG copolyester
films and sprayed with a silicone spray in similar manner to the
procedure of Example 3a. The surface of the micro-embossed films
were imaged using an EPSON STYLUS COLOR inkjet printer operating in
720 dpi mode, and Coated 720.times.720 Media setting and using the
manufacturer's recommended ink cartridges (all were aqueous dye
based inks). The films were individually applied to xerographic
paper so as to contact the ink image with the paper. Moderate hand
pressure was applied to the unimaged side of the transfer film to
effect transfer of the image to the paper, and then the image
transfer film was removed. The results for various times that the
ink sat before transfer are shown below in Table 4.
4TABLE 4 Elapsed Time between image and transfer to paper Results
Immediate (less than 1 min.) Excellent transfer, excellent
uniformity and resolution 2 hours Very good (>90 percent of ink)
transfer, some mottle, significant loss of resolution 20 hours Very
good transfer, some mottle, some loss of resolution
Example 9
[0126] A crosslinked silicone mold (SILASTIC J) having an inverse
image of the desired pattern was compression molded with 7C50
(ethylene-propylene copolymer) and THV 200 (fluoropolymer film) to
emboss a pattern of cavities 25 micrometers deep and 250
micrometers from center to center, with walls 25 micrometers thick
at the base of the wall and a 15.degree. included wall angle, onto
the substrates; the structure was confirmed in each case using
standard interferometry techniques.
[0127] SCOTCHCAL.TM. WHITE GRAPHIC MARKING FILM was micro-embossed
with a square array of cavities (0.250 millimeter micro-embossed
element pitch, 0.050 millimeter deep and surrounded by walls that
were nominally 0.025 millimeter wide). This micro-embossed pattern
was made by compression molding a SCOTCHCAL.TM. WHITE GRAPHIC
MARKING FILM against a KAPTON polyimide master having an inverse
image and prepared by laser ablation.
[0128] Each patterned substrate was subsequently printed upon with
an Hewlett-Packard HP855Cse (black ink cartridge was
Hewlett-Packard Part No. 51645A, tricolor ink cartridge was
Hewlett-Packard Part No. 51641A) and HP2000C (for ink cartridges
yellow, magenta, cyan, black Hewlett-Packard Part No. 10) desktop
printers. In each case, the print pattern was three contiguous 1
inch squares of red, green, and blue; the test pattern was printed
only in the printer mode intended for plain paper at "normal" or
standard print speed. Each print pattern was in each case
transferred immediately to an absorptive cloth, (i.e., white
WYP-ALL), which had been previously saturated with deionized water
and wrung out by hand. The image transfer was accomplished using a
small hand roller with firm pressure on the unimaged side of the
transfer film. Three to four passes with the roller were used per
transfer.
[0129] After transferring the print to the cloth, the remaining ink
on the micro-embossed substrate was measured using a Gretag SPM 55
REFLECTANCE DENSITOMETER. In each case, the level of cyan remaining
where the blue square had been printed onto the micro-embossed
substrate was measured. The density of cyan was also measured on
the unprinted micro-embossed substrates, and this baseline value
was then subtracted from the measured density after the transfer
was carried out. The cloth was also measured for ink transferred in
the same manner, where the baseline cyan density was subtracted
from that of the white substrate before transfer. The values for
each substrate are shown in Table 5.
5TABLE 5 Substrate Printer Percent Ink Transfer 7C50 film HP855Cse
96 HP2000C 95 PVC film HP855Cse 99 HP2000C 98 THV 200 film HP855Cse
100 HP2000C 97
Example 10
[0130] A printed image was generated using a Hewlett-Packard
HP855Cse inkjet printer onto the micro-embossed PVC as described in
Example 9, except that the printed image was allowed to dry for
about 24 hours before transferring the print to the cloth. The
percent ink transfer, calculated for cyan as above, was 94
percent.
Example 11
[0131] A film consisting of polyethylene coated paper with a thin
silicone topcoat was micro-embossed with Pattern 1. A 20 percent
solids solution of PVP/VA S-630 poly(vinylpyrrolidone-co-vinyl
acetate) in denatured ethanol, was coated onto the micro-embossed
film using a #4 Mayer Rod (0.0091 millimeter nominal wet thickness)
and the film was dried in a convection oven at 50.degree. C.
Polyvinyl pyrrolidone-co-vinyl acetate S-630 is a water soluble
adhesive material which becomes quite tacky, or activated, when
exposed to aqueous based fluids. To activate particular regions of
the PVP/VA S-630 coating, a Hewlett-Packard HP2000C desktop ink jet
printer with aqueous inks was used to image the coated film with a
pattern that included square regions of black and each of the three
secondary colors. The imaged side of the film was contacted with a
0.1 millimeter thick film of polyethylene terephthalate (PET) film
that had been primed with polyvinylidene chloride, and moderate
pressure was applied to the unimaged film surface with a rubber
roller to effect transfer of the ink and the PVP/VA S-630. The
transferred image appeared very bright with a minimum of smearing
and the imaged regions were tacky indicating the presence of the
PVP/VA S-630.
[0132] For a comparison, an identically micro-embossed film without
the PVP/VA S-630 coating was imaged and contacted with a primed PET
film as described above. In this case, there was significant
smearing of the inks and the imaged regions were not tacky.
Example 12
[0133] Various commercially available inkjet printers were used to
transfer images according to the invention, each using the same
transfer sheet: a silicone coated LDPE/PET/HDPE co-extruded film
transfer sheet construction with Pattern 2. The LDPE layer had the
micro-embossed pattern subsequently printed thereon.
[0134] The transfer sheet was imaged as described in Example 11
using a test pattern with 4 solid blocks of color (black, red,
green, blue) using an inkjet printer operating at its highest image
quality settings. Simultaneously, the same test pattern was also
printed (with the same printer settings) onto plain (xerographic
grade) paper.
[0135] The wet ink on each of the transfer sheets was transferred
to dry 100 percent cotton cloth (T-shirt weight). After allowing
the wet ink to fully dry at ambient conditions (more than 1 day),
the color densities of the transferred image and the comparative
image on paper were measured with a GRETAG SPM 55 REFLECTANCE
DENSITOMETER. Results are shown in Table 6.
6 TABLE 6 Reflectance Color Density Printer Substrate Black Red
Green Blue HP2000C Fabric 1.02 (poor color 0.91 0.75 0.95
uniformity, poor edge definition) HP2000C Fabric/paper 1.02 (poor
color 0.91/ 0.75/ 0.95/ uniformity, 1.00 0.89 1.09 poor edge
definition)/ 0.97 HP-870C Paper/fabric 0.97/1.04 1.00/ 0.89/ 1.09/
1.10 0.93 1.27 HP-870C Fabric/paper 1.04/1.36 1.10/ 0.93/ 1.27/
1.11 0.99 1.25 HP855Cse Paper/fabric 1.36/0.93 1.11/ 0.99/ 1.25/
1.14 0.97 1.36 HP855Cse Fabric/paper 0.93/1.41 1.14/ 0.97/ 1.36/
1.08 0.96 1.27 HP680C Paper/fabric 1.41/1.04 1.08/ 0.96/ 1.27/ 1.34
1.08 1.39 HP680C Fabric/paper 1.04/1.32 1.34/ 1.08/ 1.39/ 1.11 1.05
1.27 Canon-7000 Paper/fabric 1.32/0.71 1.11/ 1.05/ 1.27/ 0.78 0.63
0.93 Canon-7000 Fabric/paper 0.71/1.12 0.78/ 0.63/ 0.93/ 1.04 0.88
1.02 Paper 1.12 1.04 0.88 1.02
Examples 13 and 14
[0136] These examples show that various micro-embossed elements on
a substrate will work in the same fashion with similar
micro-embossed capacities to provide for aqueous ink transfer to
cotton fabric.
[0137] Two sample films of 7C50 (ethylene-propylene copolymer) were
micro-embossed to provide substrates with micro-embossed patterns.
Example 13 had a truncated pyramidal pattern of cavities or
cavities of 70 micrometers micro-embossed element pitch, with 5
micrometer wall thickness at the wall tops. Depth of the truncated
pyramid was 25 micrometers and the wall bases had a thickness of 19
micrometers. The pattern of Example 14 had cavities of similar
dimensions to that of Example 13, but completely without corners or
flat areas. The micro-embossed pattern of Example 14 was a random
pattern of hemispherical cavities of diameter 50-60 micrometers and
a depth of 25-30 micrometers, randomly packed.
[0138] Each patterned transfer film was subsequently printed upon
with a Hewlett-Packard HP680C desktop printer. The print pattern
was three contiguous 1 inch squares of red, green, and blue; the
test pattern was printed only in the printer mode intended for
plain paper at "normal" or standard print speed. The printed image
in each case was transferred immediately to a cotton T-shirt
material, which had been dampened prior to the transfer with
deionized water to about 100 percent wet pickup based on the
initial weight of the material. The image transfer was accomplished
using a small hand roller with firm pressure on the unimaged
surface of the transfer film. Three to four passes with the roller
were used per image transfer.
[0139] After transferring the printed image to the cloth, the
remaining ink on each micro-embossed transfer film was measured
using a GRETAG SPM 55 REFLECTANCE DENSITOMETER. In each case, the
level of cyan remaining where the blue square had been printed onto
the micro-embossed transfer film was measured. The reflectance
color density of cyan was also measured on the unprinted
micro-embossed transfer films, and this baseline value was then
subtracted from the measured densities of cyan after the transfer
was carried out. The results were as follows: Truncated pyramid
pattern: cyan=0.083; Hemispherical pattern: cyan=0.094.
[0140] The data show that micro-embossed patterns of similar
dimensions on the same nonporous film will transfer inks similarly,
regardless of the shape of the cavities.
Example 15
[0141] Pattern 1 was micro-embossed into a polyethylene coated
paper with a thin silicone release coating. A Hewlett-Packard
HP-870C desktop inkjet printer using transparency mode, best
quality settings, was used to image the micro-embossed side of the
film with a pattern consisting of a 2.54 centimeter wide red
stripe. With the imaged surface facing outward, the film was wound
and attached onto a 3 inch diameter cardboard core. Moderate
pressure was applied by hand as the core was rolled against 100
percent cotton T-shirt fabric.
[0142] Approximately 50 percent of the ink transferred from the
film to the cotton as determined by comparison of the image density
of the ink remaining on the film to the ink transferred to the
cotton.
Example 16
[0143] SCOTCHCAL.TM. WHITE GRAPHIC MARKING FILM was micro-embossed
as described in Example 9. A Hewlett-Packard HP-870C desktop inkjet
printer using paper mode, normal quality, was used to image the
micro-embossed side of the film with a pattern consisting of
adjacent boxes of cyan, magenta and yellow. The imaged film was
then attached to a 61 centimeter long section of unembossed
SCOTCHCAL.TM. WHITE GRAPHIC MARKING FILM and the film was wound
into an overlapping roll with a diameter of approximately 1.2
centimeter so that the imaged side of the film faced inward.
[0144] To form an image, the roll was unwound as the imaged side
was contacted with a 100 percent cotton T-shirt fabric. Moderate
finger pressure was used to transfer ink from the imaged regions of
the micro-embossed film to the cotton fabric. Approximately 60
percent of the ink jetted onto the film was transferred to the
cotton as determined comparisons of the image density of the ink
remaining on the film to the ink transferred to the cotton.
Comparative Example 3
[0145] Using a Hewlett-Packard DeskJet HP-870C thermal inkjet
printer in plain paper mode at normal print speed, an image of red
and blue blocks (100 percent ink complement) with contrasting red
and blue lines running through them was generated as a test print.
This image was printed onto polyethylene coated paper with a thin
silicone release coating. A representative printed area of the
image is shown in FIG. 8 in magnified form.
Example 17
[0146] Comparative Example 3 was repeated, except that Pattern 1
was used. A printed area corresponding to the same printed area
shown in FIG. 9 is shown in FIG. 10 in magnified form. The ink
residing in the corners of the square cavities is clearly visible
in FIG. 10.
[0147] The prints were smeared about 5 minutes after exiting the
printer at the same location in each test pattern, using light
finger pressure. The image on Comparative Example 3 was
catastrophically smeared (i.e., all ink was easily removed) as
shown in FIG. 11 in magnified form. The image of Example 17,
however, underwent only very slight damage during smear as shown in
FIG. 12 in magnified form.
Comparative Example 4
[0148] ASPEN SELECT GRADE HOBBY WOOD was sanded with a 3M FINE
GRADE SANDING SPONGE before addition of fixing agent. The fixing
agent used was 95 weight percent DISPAL 23N4-20 and 5 percent
FREESOFT 970. The aqueous mixture (20 percent total solids) was
sprayed onto one side of the wood to give an average wet coating
weight of 50 g/m.sup.2.
[0149] A test pattern consisting of adjacent colored blocks of
cyan, magenta, yellow, black, red, green, and blue, along with
narrow lines of these colors crossing color bars, were printed onto
silicone coated LDPE/PET/HDPE film using a Hewlett-Packard DESKJET
HP855Cse thermal inkjet printer in high quality/glossy paper mode.
The inked side of the image transfer film was subsequently placed
in intimate contact with the treated aspen prepared above, and
sufficient pressure applied to cause transfer of the image to the
wood. FIG. 13 depicts the magnified image formed in this
manner.
Example 18
[0150] Comparative Example 4 was repeated except that Pattern 2 was
micro-embossed into the image transfer film. FIG. 14 depicts the
magnified image formed in this manner.
[0151] The resulting transferred images clearly showed differences
in resolution attributable to the presence or absence of the
patterned film used to effect the transfer of ink to the wood
surface. The transferred image from the smooth film is prone to
show where the ink beaded up, ran together in an uncontrolled
fashion, and/or smeared before or during transfer. By comparison,
the image transferred by the micro-embossed film has good
resolution and ink placement.
Example 19
[0152] This example demonstrates the use of microstructures
consisting of posts or combinations of posts and wells as image
transfer films.
[0153] A film consisting of polyethylene coated paper with a thin
silicone topcoat (as in Example 12) was embossed with an array of
hexagonally packed posts which were about 92 micrometers in
diameter at the top and 110 micrometers in diameter at the base of
the post. An additional sample of the same film was embossed with a
pattern consisting of both an array of 15 micrometer deep hexagonal
wells with an overall pitch of 100 lines per inch (39.4 lines/cm)
and a random arrangement of 75 micrometer tall posts packed with an
average density of about 4.6 posts/mm.sup.2 superimposed throughout
the well structure. The well walls were 2 micrometers wide at the
top and 11 micrometers wide at the bottom, while the posts were 31
micrometers in diameter at the top and 59 micrometers in diameter
at the bottom.
[0154] An HP2000C ink jet printer equipped with aqueous inks was
used to image each of the embossed films with a pattern consisting
of adjacent squares of red, green and blue using paper mode, normal
quality. For comparative purposes, an unembossed sheet of
polyethylene coated paper with a thin silicone topcoat was also
imaged. Each of the freshly imaged films were then smeared with
light finger pressure. As shown in FIGS. 15 (unembossed), 16
(hexagonally packed posts) and 17 (hexagonal cavities and random
posts) the smear resistance of the embossed films were superior to
the unembossed films.
[0155] The imaged surface of each of these films were then
contacted with a sheet of bond paper (75 g/m.sup.2, available from
Boise Cascade Paper Division, Boise, Id., USA) and moderate
pressure was applied to the unimaged side of the film with a lab
roller to effect transfer of the image to the paper. The efficiency
of the transfer was determined by comparing the amount of ink
transferred to the paper to the amount of ink remaining on the
transfer film.
[0156] Table 7 shows the ratio of red ink transferred to red ink
remaining on the transfer film. In each case, the red ink density
was determined by averaging the yellow and magenta intensities that
were measured using a Gretag SPM reflectance densitometer. Table 7
shows that image transfer media having embossed post patterns
according to the invention provides acceptable ink transfer and
protects the image transfer medium from accidental smearing.
7TABLE 7 Ratio of Ink Transferred to Ink Remaining: Transfer Film
for Several Patterns Pattern Ink Transferred:Ink remaining
Hexagonally Packed Posts 7.9 Hex Wells + Random Posts 12.4
Unembossed .about.Complete transfer
Example 20
[0157] Table 8 shows a composition (Composition 1) of a coating
solution coated onto the color/image transfer medium surface. The
composition is prepared by mixing a copolyester resin (VITEL
-2700B) in a glass beaker (1 L capacity) using a mechanical stirrer
at ambient temperature.
8 TABLE 8 Component Weight/g Weight % VITEL-2700B 75 g 15% Toluene
360 g 72% Isopropyl Alcohol 65 g 13% Total = 500 g
[0158] Compositon-1 was coated onto a silicone coated LDPE/PET/HDPE
film having Pattern 2 micro-embossed thereon. The film was air
dried for 10 min or dried at .about.50.degree. C. for {fraction
(1/2)} min to obtain a clear-coated film. When imaged using a
Hewlett Packard HP855Cse or HP2000C, LEXMARK Z11 or Epson 2
printer, the image transfer medium provided a higher density
solid-color image which was recognizable by the naked eye. The
color/image densities of the colors on this medium were compared
with transfer media having no Composition-1 coating. The data is
shown in Table 9 below.
9TABLE 9 Micro-embossed LDPE/PET/HDPE Color Density (Pattern 2)
Printer Green Red Blue Magenta No Coating/15 .mu.m HP855Cse 0.560
0.481 0.496 0.361 With Coating/15 .mu.m " 1.753 1.730 1.812 1.064
No Coating/25 .mu.m " 0.323 0.309 0.303 0.196 With Coating/25 .mu.m
" 0.984 0.879 0.948 0.591 No Coating/15 .mu.m HP2000C 0.490 0.534
0.443 0.437 With Coating/15 .mu.m " 1.563 1.949 1.545 1.448 No
Coating/15 .mu.m LEXMARK 0.352 0.375 0.324 0.330 Z11 With
Coating/15 .mu.m " 0.562 0.517 0.487 0.455 No Coating/25 .mu.m "
0.350 0.311 0.223 0.210 With Coating/25 .mu.m " 0.449 0.463 0.411
0.345 No Coating/15 .mu.m Epson II 0.289 0.253 0.272 0.240 With
Coating/15 .mu.m " 0.698 0.541 0.847 0.532 Micro-embossed
LDPE/PET/HDPE Color Density (Pattern 2) Printer Cyan Yellow Black
No Coating/15 .mu.m HP855Cse 0.369 0.340 0.327 With Coating/15
.mu.m " 1.379 1.064 0.477 No Coating/25 .mu.m " 0.196 0.190 0.193
With Coating/25 .mu.m " 0.732 0.600 0.456 No Coating/15 .mu.m
HP2000C 0.360 0.485 0.322 With Coating/15 .mu.m " 1.201 1.626 0.670
No Coating/15 .mu.m LEXMARK 0.305 0.361 0.392 Z11 With Coating/15
.mu.m " 0.507 0.532 0.557 No Coating/25 .mu.m " 0.201 0.195 0.358
With Coating/25 .mu.m " 0.377 0.364 0.557 No Coating/15 .mu.m Epson
II 0.252 0.197 0.245 With Coating/15 .mu.m " 0.700 0.205 0.321
[0159] The data show that the Composition-1 coating significantly
enhanced the color/image density and provided improved color
uniformity to the color/image on the uncoated image transfer
medium.
Example 21
[0160] Table 10 shows a comparison of % Color Image transfer from
an uncoated image transfer medium and an image transfer medium
coated with Composition 1. An image receiving medium was prepared
by coating a piece of 100% cotton T-shirt cloth with a coating
prepared by combining 60 g VIVIPRINT 111, 80 g deionized water, 60
g DISPAL 11N7-12, 12 g AIRFLEX 460, 60 g of a mixture of 8 g
Al.sub.2(SO.sub.4).sub.3.14H.sub.20 and 1.67 g dihexyl
sulfosuccinate in a mixture of 75 g deionized water and 25 g
isopropanol, and 20 g of 1 weight percent aqueous sodium
carboxymethylcellulose in deionized water. The coating process was
carried out using a using a #26 Mayer rod followed by drying of the
coating.
[0161] Image transfer was carried out by intimately contacting the
imaged surface of the image transfer medium with the receptor sheet
and rubbing with pressure applied by hand.
[0162] Composition 1 did not have any affect on the color/image
transfer. Color density of the imaged film was measured in a
densitometer and the results are shown in Table 10.
10TABLE 10 Micro-embossed LDPE/PET/HDPE % Color/Image Transfer
(Pattern 2) Printer Colors* Black No Coating/15 .mu.m HP855Cse 94
52 With Coating/15 .mu.m " 89 41 No Coating/15 .mu.m HP2000C 93 48
With Coating/15 .mu.m " 91 22 No Coating/15 .mu.m LEXMARK Z11 98
With Coating/15 .mu.m " 98 No Coating/15 .mu.m Epson II 94 72 With
Coating/15 .mu.m " 91 47 No Coating/15 .mu.m Epson Photo 78 83 With
Coating/15 .mu.m " 82 76 *based on average density of all the
colors
Example 22
[0163] This example shows the dry time of an imaged uncoated image
transfer medium and an image transfer medium coated with
Composition 1 at ambient temperature. Dry time was measured by (1)
observing the disappearance of wetness on the film and (2) by
laying a piece of plain paper onto the color/image (without putting
any hand pressure) observing color transfer (if any) to the plain
paper.
11 TABLE 11 Micro-embossed LDPE/PET/HDPE (Pattern 2) Printer
Dry-Time No Coating/15 .mu.m HP855Cse indefinite With Coating/15
.mu.m " 7-8 minutes No Coating/25 .mu.m " indefinite With
Coating/25 .mu.m " 7-8 minutes No Coating/15 .mu.m HP2000C
indefinite With Coating/15 .mu.m " 20 minutes No Coating/15 .mu.m
LEXMARK Z11 indefinite With Coating/15 .mu.m " .sub..about.2 days
No CoatinG/25 .mu.m " indefinite With Coating/25 .mu.m "
.sub..about.2 days No Coating/15 .mu.m Epson II indefinite With
Coating/15 .mu.m " .sub..about.1 hour No Coating/15 .mu.m Epson
Photo indefinite With Coating/15 .mu.m " .sub..about.1 hour
Example 23
[0164] This example shows that a color/image can be transferred
from a color/image transfer medium coated with Composition 1 after
imaging at various times.
12TABLE 12 Coated Color Micro-embossed Transfer Time LDPE/PET/HDPE
(After Color % Color (Pattern 2) Printer Printing) Transfer 15
.mu.m HP855Cse 1/2 hour 92 24 hours 93 48 hours 89 15 .mu.m HP2000C
1/2 hour 95 24 hours 93 48 hours 92
[0165] Various modifications and alterations of this invention will
become apparent to those skilled in the art without departing from
the scope and spirit of this invention, and it should be understood
that this invention is not to be unduly limited to the illustrated
embodiments set forth herein.
* * * * *