U.S. patent application number 10/443541 was filed with the patent office on 2003-10-30 for digital color-design composite for use in laminated glass.
This patent application is currently assigned to Solutia Inc. Invention is credited to Bell, William Paul, Moran, James R., Yacovone, Vincent J..
Application Number | 20030203167 10/443541 |
Document ID | / |
Family ID | 29249453 |
Filed Date | 2003-10-30 |
United States Patent
Application |
20030203167 |
Kind Code |
A1 |
Bell, William Paul ; et
al. |
October 30, 2003 |
Digital color-design composite for use in laminated glass
Abstract
This invention is directed to a plastic composite comprising
color images printed onto a polyethylene terephthalate (PET)
substrate using digital printing technology. The PET layer is then
bonded to a second PET layer using a thermally activated adhesive,
preferably ethylene vinyl acetate copolymer (EVA). The bonded PET
layers are then disposed between two layers of plasticized PVB,
forming the plastic composite. The plastic composite can then be
placed between two sheets of glass forming the final laminated
glass product.
Inventors: |
Bell, William Paul; (Reston,
VA) ; Moran, James R.; (Longmeadow, MA) ;
Yacovone, Vincent J.; (Springfield, MA) |
Correspondence
Address: |
Craig M. Lundell
Howrey Simon Arnold & White, LLP
750 Bering Drive
Houston
TX
77057
US
|
Assignee: |
Solutia Inc
|
Family ID: |
29249453 |
Appl. No.: |
10/443541 |
Filed: |
May 22, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10443541 |
May 22, 2003 |
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10135417 |
Apr 30, 2002 |
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Current U.S.
Class: |
428/195.1 ;
428/430; 428/435 |
Current CPC
Class: |
Y10T 428/31627 20150401;
B32B 17/10018 20130101; B32B 17/10036 20130101; Y10T 428/24802
20150115; B32B 17/10247 20130101; Y10T 428/31623 20150401; Y10T
428/2495 20150115; Y10T 428/3163 20150401; Y10T 428/2848 20150115;
B32B 17/10788 20130101; Y10T 428/264 20150115; Y10T 428/28
20150115; Y10T 428/31786 20150401; Y10T 428/31725 20150401; B32B
17/10339 20130101; B32B 17/10935 20130101; B32B 27/36 20130101;
B32B 17/10981 20130101; Y10T 428/31616 20150401; Y10T 428/2874
20150115; Y10T 428/31645 20150401; B32B 17/10275 20130101; B32B
17/10284 20130101; B32B 17/10761 20130101; B32B 17/10577 20130101;
Y10T 428/2813 20150115; B32B 17/10005 20210101; B32B 2367/00
20130101 |
Class at
Publication: |
428/195.1 ;
428/435; 428/430 |
International
Class: |
B32B 009/00 |
Claims
We claim:
1. An interlayer for laminated glass, the interlayer comprising a
polymeric support film supporting at least one color image; a
polymeric film bonded to the polymeric support film, such that the
color image is between the polymeric support film and the polymeric
film; a first adhesive layer bonded to the polymeric support film;
and a second adhesive layer bonded to the polymeric film.
2. The interlayer of claim 1, wherein the polymeric support film
and the polymeric film are individually selected from the group
consisting of nylons, epoxies, polyurethanes, polyacrylates,
polycarbonates, cellulose acetates, cellulose triacetates, vinyl
chloride polymers, vinyl chloride copolymers and polyesters.
3. The interlayer of claim 1, wherein both the polymeric support
film and the polymeric film are biaxially stretched polyethylene
terephthalate.
4. The interlayer of claim 1, wherein the polymeric film is
provided by coating the polymeric support film with a reactive
mixture and then curing the reactive mixture using ultraviolet
light or heat.
5. The interlayer of claim 4, wherein the reactive mixture is
selected from the group consisting of polyacrylate, epoxy,
polyester or polyurethane chemistries.
6. The interlayer of claim 1, wherein the polymeric film is
provided by coating the polymeric support film with an aqueous
emulsion or a solvent based polymer solution and then removing the
water or solvent component by evaporation.
7. The interlayer of claim 6, wherein the polymer used with the
aqueous emulsion or solvent based solution is selected from the
group consisting of polyacrylate, epoxy, polyester or polyurethane
chemistries.
8. The interlayer of claim 1, wherein the color image is printed on
the polymeric support film using digital printing technology.
9. The interlayer of claim 8, wherein the color image is printed on
the polymeric support film using thermal transfer printing
technology.
10. The interlayer of claim 8, wherein the color image is printed
on the polymeric support film using inkjet printing technology.
11. The interlayer of claim 1, wherein the polymeric support film
is bonded to the polymeric film using a thermally activated
adhesive
12. The interlayer of claim 11, wherein the thermally activated
adhesive is ethylene vinyl acetate copolymer.
13. The interlayer of claim 1, wherein the polymeric support film
and polymeric film are bonded together with a minimum bond strength
of 4 N/cm.
14. The interlayer of claim 1, wherein the polymeric support film
and polymeric film are bonded together with a preferred bond
strength of at least 8 N/cm.
15. The interlayer of claim 1, wherein the thickness of the
polymeric support film is between about 25 to 250 micrometers and
the polymeric film is between about 10 to 125 micrometers.
16. The interlayer of claim 15, wherein the thickness of the
polymeric support film is about 75 micrometers.
17. The interlayer of claim 15, wherein the thickness of the
polymeric film is about 75 micrometers.
18. The interlayer of claim 1, wherein the adhesive layer is
selected from the group consisting of polyurethane, ethylene vinyl
acetate copolymer, plasticized polyvinyl chloride and plasticized
polyvinyl butyral.
19. The interlayer of claim 18, wherein the adhesive layer is
plasticized polyvinyl butyral.
20. The interlayer of claim 19, wherein the plasticized polyvinyl
butyral is plasticized with a plasticizer selected from the group
consisting of triethylene glycol di-(2-ethylbutyrate),
triethyleneglycol di-(2-ethylhexanoate), tetraethyleneglycol
diheptanoate, dihexyl adipate, dioctyl adipate, mixtures of heptyl
and nonyl adipates, dibutyl sebacate, polymeric plasticizers, and
mixtures of phosphates and adipates, mixtures of adipates and alkyl
benzyl phthalates, mixed adipates made from C.sub.4 to C.sub.9
alkyl alcohols and cyclo C.sub.4 to C.sub.10 alcohols, C.sub.6 to
C.sub.8 adipate esters, and mixtures thereof.
21. The interlayer of claim 1, wherein one or both of the adhesive
layers comprise an ultra-violet light absorber.
22. The interlayer of claim 1, wherein one or both of the polymeric
support film or the polymeric film comprise an ultra-violet light
absorber.
23. The interlayer of claim 1, wherein one or both of the adhesive
layers are colored.
24. The interlayer of claim 1, wherein the first and the second
adhesive layers have a thickness of about 0.38 to 1.5 mm.
25. The interlayer of claim 1, wherein the surfaces of the
polymeric support film and the polymeric film in contact with the
adhesive layers are chemically modified using a process selected
from the group consisting of flame treatment, chemical oxidation,
corona discharge, carbon sputtering, plasma treatment in vacuum,
and plasma treatment in air.
26. The interlayer of claim 1, wherein an adhesive is applied to
the surfaces of the polymeric support film and polymeric film in
contact with the adhesive layers.
27. The interlayer of claim 1, wherein the color image is selected
from the group consisting of a logo, symbol, geometric pattern,
photograph, alphanumeric characters and combinations thereof.
28. The interlayer of claim 1 wherein the color image is printed on
an image layer comprising a polymer film selected from the group
consisting of polyvinyl butyral, nylons, epoxies, polyurethanes,
polyacrylates, polycarbonates, cellulose acetates, cellulose
triacetates, vinyl chloride polymers, vinyl chloride copolymers and
polyesters.
29. The interlayer of claim 28 wherein the color image is printed
on an image layer comprising a polyvinyl butyral polymer film.
30. The interlayer of claim 29 wherein the color image is printed
by inkjet technology on an image layer comprising a polyvinyl
butyral polymer film.
31. A laminated glass composite comprising an interlayer disposed
between two glass sheets, the interlayer comprising a polymeric
support film supporting at least one color image; a polymeric film
bonded to the polymeric support film, such that the color image is
between the polymeric support film and the polymeric film; a first
adhesive layer bonded to the polymeric support film; and a second
adhesive layer bonded to the polymeric film.
32. The laminated glass composite of claim 31, wherein the two
glass sheets are a pair of matching float glass sheets.
33. The laminated glass composite of claim 31, wherein the two
glass sheets are individually selected from the group consisting of
clear glass, tinted glass, annealed glass, heat strengthened glass,
and tempered glass.
34. The laminated glass composite of claim 31, wherein the
polymeric support film and the polymeric film are individually
selected from the group consisting of nylons, epoxies,
polyurethanes, polyacrylates, polycarbonates, cellulose acetates,
cellulose triacetates, vinyl chloride polymers, vinyl chloride
copolymers and polyesters.
35. The laminated glass composite of claim 31, wherein both the
polymeric support film and the polymeric film are biaxially
stretched polyethylene terephthalate.
36. The laminated glass composite of claim 31, wherein the
polymeric film is provided by coating the polymeric support film
with a reactive mixture and then curing the reactive mixture using
ultraviolet light or heat.
37. The laminated glass composite of claim 36, wherein the reactive
mixture is selected from the group consisting of polyacrylate,
epoxy, polyester or polyurethane chemistries.
38. The laminated glass composite of claim 31, wherein the
polymeric film is provided by coating the polymeric support film
with an aqueous emulsion or a solvent based polymer solution and
then removing the water or solvent component by evaporation.
39. The laminated glass composite of claim 38, wherein the polymer
used with the aqueous emulsion or solvent based solution is
selected from the group consisting of polyacrylate, epoxy,
polyester or polyurethane chemistries.
40. The laminated glass composite of claim 31, wherein the color
image is printed on the polymeric support film using digital
printing technology.
41. The laminated glass composite of claim 40, wherein the color
image is printed on the polymeric support film using thermal
transfer printing technology.
42. The laminated glass composite of claim 40, wherein the color
image is printed on the polymeric support film using inkjet
printing technology.
43. The laminated glass composite of claim 31, wherein the
polymeric support film is bonded to the polymeric film using a
thermally activated adhesive
44. The laminated glass composite of claim 43, wherein the
thermally activated adhesive is ethylene vinyl acetate
copolymer.
45. The laminated glass composite of claim 31, wherein the
polymeric support film and polymeric film are bonded together with
a minimum bond strength of 4 N/cm.
46. The laminated glass composite of claim 31, wherein the
polymeric support film and polymeric film are bonded together with
a preferred bond strength of at least 8 N/cm.
47. The laminated glass composite of claim 31, wherein the
thickness of the polymeric support film is between about 25 to 125
micrometers and the polymeric film is between about 10 to 125
micrometers.
48. The laminated glass composite of claim 47, wherein the
thickness of the polymeric support film is about 75
micrometers.
49. The laminated glass composite of claim 47, wherein the
thickness of the polymeric film is about 75 micrometers.
50. The laminated glass composite of claim 31, wherein the adhesive
layer is selected from the group consisting of polyurethane,
ethylene vinyl acetate copolymer, plasticized polyvinyl chloride
and plasticized polyvinyl butyral.
51. The laminated glass composite of claim 50, wherein the adhesive
layer is plasticized polyvinyl butyral.
52. The laminated glass composite of claim 51, wherein the
plasticized polyvinyl butyral is plasticized with a plasticizer
selected from the group consisting of triethylene glycol
di-(2-ethylbutyrate), triethyleneglycol di-(2-ethylhexanoate),
tetraethyleneglycol diheptanoate, dihexyl adipate, dioctyl adipate,
mixtures of heptyl and nonyl adipates, dibutyl sebacate, polymeric
plasticizers, and mixtures of phosphates and adipates, mixtures of
adipates and alkyl benzyl phthalates, mixed adipates made from
C.sub.4 to C.sub.9 alkyl alcohols and cyclo C.sub.4 to C.sub.10
alcohols, C.sub.6 to C.sub.8 adipate esters, and mixtures
thereof.
53. The laminated glass composite of claim 31, wherein one or both
of the adhesive layers comprise an ultra-violet light absorber.
54. The laminated glass composite of claim 31, wherein one or both
of the polymeric support film or the polymeric film comprise an
ultra-violet light absorber.
55. The laminated glass composite of claim 31, wherein one or both
of the adhesive layers are colored.
56. The laminated glass composite of claim 31, wherein the first
and the second adhesive layers have a thickness of about 0.38 to
1.5 mm.
57. The laminated glass composite of claim 31, wherein the surfaces
of the polymeric support film and the polymeric film in contact
with the adhesive layers are chemically modified using a process
selected from the group consisting of flame treatment, chemical
oxidation, corona discharge, carbon sputtering, plasma treatment in
vacuum, and plasma treatment in air.
58. The laminated glass composite of claim 31, wherein an adhesive
is applied to the surfaces of the polymeric support film and
polymeric film in contact with the adhesive layers.
59. The laminated glass composite of claim 31, wherein the color
image is selected from the group consisting of a logo, symbol,
geometric pattern, photograph, alphanumeric characters and
combinations thereof.
60. The laminated glass composite of claim 31 wherein the color
image is printed on an image layer comprising a polymer film
selected from the group consisting of polyvinyl butyral, nylons,
epoxies, polyurethanes, polyacrylates, polycarbonates, cellulose
acetates, cellulose triacetates, vinyl chloride polymers, vinyl
chloride copolymers and polyesters.
61. The laminated glass composite of claim 60 wherein the color
image is printed on an image layer comprising a polyvinyl butyral
polymer film.
62. The laminated glass composite of claim 61 wherein the color
image is printed by inkjet technology on an image layer comprising
a polyvinyl butyral polymer film.
63. An interlayer comprising a polymeric support film supporting at
least one color image; a polymeric film bonded to the polymeric
support film, such that the color image is between the polymeric
support film and the polymeric film; wherein the interlayer is used
in a glass laminate.
64. The interlayer of claim 63, wherein the polymeric support film
and the polymeric film are individually selected from the group
consisting of nylons, epoxies, polyurethanes, polyacrylates,
polycarbonates, cellulose acetates, cellulose triacetates, vinyl
chloride polymers, vinyl chloride copolymers and polyesters.
65. The interlayer of claim 63, wherein both the polymeric support
film and the polymeric film are biaxially stretched polyethylene
terephthalate.
66. The interlayer of claim 63, wherein the polymeric film is
provided by coating the polymeric support film with a reactive
mixture and then curing the reactive mixture using ultraviolet
light or heat.
67. The interlayer of claim 66, wherein the reactive mixture is
selected from the group consisting of polyacrylate, epoxy,
polyester or polyurethane chemistries.
68. The interlayer of claim 63, wherein the polymeric film is
provided by coating the polymeric support film with an aqueous
emulsion or a solvent based polymer solution and then removing the
water or solvent component by evaporation.
69. The interlayer of claim 68, wherein the polymer used with the
aqueous emulsion or solvent based solution is selected from the
group consisting of polyacrylate, epoxy, polyester or polyurethane
chemistries.
70. The interlayer of claim 68, wherein the reactive mixture is
selected from the group consisting of polyacrylate, epoxy,
polyester or polyurethane chemistries.
71. The interlayer of claim 53, wherein the color image is printed
on the polymeric support film using digital printing
technology.
72. The interlayer of claim 71, wherein the color image is printed
on the polymeric support film using thermal transfer printing
technology.
73. The interlayer of claim 63, wherein the color image is printed
on the polymeric support film using inkjet printing technology.
74. The interlayer of claim 63, wherein the polymeric support film
is bonded to the polymeric film using a thermally activated
adhesive
75. The interlayer of claim 74, wherein the thermally activated
adhesive is ethylene vinyl acetate copolymer.
76. The interlayer of claim 63, wherein the polymeric support film
and polymeric film are bonded together with a minimum bond strength
of 4 N/cm.
77. The interlayer of claim 63, wherein the polymeric support film
and polymeric film are bonded together with a preferred bond
strength of at least 8 N/cm.
78. The interlayer of claim 63, wherein the thickness of the
polymeric support film is between about 25 to 125 micrometers and
the polymeric film is between about 10 to 125 micrometers.
79. The interlayer of claim 78, wherein the thickness of the
polymeric support film is about 75 micrometers.
80. The interlayer of claim 78, wherein the thickness of the
polymeric film is about 75 micrometers.
81. The interlayer of claim 63, wherein one or both of the
polymeric support film and the polymeric film comprise an
ultra-violet light absorber.
82. The interlayer of claim 63, wherein the color image is selected
from the group consisting of a logo, symbol, geometric pattern,
photograph, alphanumeric characters and combinations thereof
83. The interlayer of claim 63 wherein the color image is printed
on an image layer comprising a polymer film selected from the group
consisting of polyvinyl butyral, nylons, epoxies, polyurethanes,
polyacrylates, polycarbonates, cellulose acetates, cellulose
triacetates, vinyl chloride polymers, vinyl chloride copolymers and
polyesters.
84. The interlayer of claim 83 wherein the color image is printed
on an image layer comprising a polyvinyl butyral polymer film.
85. The interlayer of claim 84 wherein the color image is printed
on the polymeric support film using inkjet printing technology.
Description
[0001] This application is a continuation in part of application
Ser. No. 10/135,417, filed Apr. 30, 2002.
BACKGROUND
[0002] There is significant commercial interest in the fabrication
of customized glass laminates with encapsulated digitally printed
images having vibrant colors for use in architectural and
automotive applications. Because project delivery times for current
methods of producing limited quantities of glass laminates with
customized graphics can be very long with accompanying high costs,
there is a strong market need for methods that will allow rapid
turnaround time at reasonable cost.
[0003] Up to now options to create such laminates have been
virtually limited to traditional screen printing methods involving
the deposition of solvent based colored inks onto plastic
substrates and subsequent encapsulation of the printed film in
glass using multiple layers of adhesive. This screen printing
process involves time consuming and costly preparation of multiple
screens--one for each color separation. Issues related to the use
of solvents must be managed in order to prevent environmental
problems. In addition, the required setup and cleanup times result
in a process that is not cost effective for limited quantities of
printed film.
[0004] Digital printing methods such as inkjet and thermal transfer
printing seem like a natural fit for production of glass laminates
with customized graphics, with each technology having its own
distinct advantages. While most commercial uses of inkjet printing
utilize opaque substrates such as white polyester, paper or white
polyvinyl chloride film (white vinyl) for optimum appearance, clear
films are also available. Thermal transfer print technology is also
able to print on many clear films so encapsulation of these printed
color images in glass laminates for customized applications
provides an opportunity to deliver a see-through laminate
appearance desired in many glass applications.
[0005] Thermal transfer color printing was developed in early
1980's and first used in commercial color printers for corporate
office printing. In the mid-1990's inkjet printing technology
became dominant because of its much lower cost. Thermal transfer
printing is still broadly used today for numerous applications such
as printing bar codes onto labels and tags. Inkjet is the dominant
print technology in many markets, including desktop publishing and
digital photography processing. It continues to expand into other
areas such as textile and fabric printing.
[0006] Thermal transfer printing is a dry-imaging process that
involves the use of a printhead containing many resistive heating
elements that selectively transfer solid ink from a coated ribbon
to a substrate. As the coated ribbon is transported through the
print head, targeted areas of the ink layer are heated, softened
and transferred to the substrate. The consumed ribbon is usually
rewound and disposed.
[0007] The resolution of a typical thermal transfer printer is
usually around 200-400 dpi with software capability to utilize
variable dot shapes and screen angles so that output quality can be
very high quality depending upon media used. Because the ink is not
required to pass through a small nozzle in the printhead, larger
pigment particles and greater pigment loadings can be used to
achieve a durability and vibrancy of color. However, achieving
acceptable quality on clear media is more challenging than opaque
media and because there is little commercial activity in this area,
the print media choices are limited which can also affect the
quality.
[0008] Inkjet printing is usually a wet-imaging and non-contact
process where a vehicle or carrier fluid is energized to "jet" ink
components from a printhead over a small distance onto a substrate.
The vehicle can be solvent or aqueous based and may contain dyes or
pigments. Along with the chromophore, an inkjet ink formulation may
contain humectants, surfactants, biocides and penetrants along with
other ingredients. Inkjet technologies include continuous and
drop-on-demand types, with drop-on-demand printing being the most
common. While the printhead, or arrays of the same, traverse the
web, there are two main types. Thermal printheads are used with
aqueous inks and piezo-electric types are used with solvents.
Knowledge of the printhead, ink formulation and substrate are
critical to producing a good image. Printer resolutions can now
exceed 1440 dpi with photographic and continuous tone
capabilities.
[0009] A major advantage of digital printing is the minimal setup
times required to produce an image which reduces the cost and
turnaround time of a short run as compared to traditional screen
printing operations.
[0010] There are numerous types of ink formulations used for
thermal transfer print ribbons including those that are primarily
wax, wax/resin or resin based. Resin based ribbons are usually more
expensive and are primarily used for production of more durable
images with the ability to withstand outdoor exposure for up to 3-5
years without lamination. Wax based ribbons are usually less
expensive and used for less demanding applications.
[0011] Thermal transfer printing has been used for many years in
the printing of bar codes on labels, tags, and tickets and the
technology for production of these ribbons has become very
specialized.
[0012] A typical color ribbon is a relatively complex composite
structure that has been developed to provide for optimum
performance in the thermal transfer printing process. A typical
high performance thermal transfer color ribbon consists of a very
thin biaxially oriented polyethylene terephthalate (PET) film
substrate usually with a thickness of .about.3-6 micrometers that
acts as a carrier or support layer for the ink layer(s). PET film
is selected as the preferred substrate because of its physical
properties and ability to withstand print head temperatures of up
to 120.degree. C. This PET substrate is coated on one side with at
least one thin layer of pigmented resin. With many resin based
color ribbons there is also a release layer between the PET
substrate and the pigmented ink layer to facilitate transfer of the
ink layer to the print media. Such a release layer will end up on
top of the image that in many applications will provide additional
protection for the printed image. On the other side of the thin
substrate is usually a "backcoating" that provides the correct
frictional properties between the printhead and the ribbon.
[0013] U.S. Pat. No. 5,939,207, the contents of which are
incorporated herein by reference, describes the composition of a
four layer thermal transfer ribbon structure for use in the
printing of black bar codes. With minor changes, this structure is
thought to be representative of a typical color ribbon formulation
utilized with the present invention. This structure described in
the '207 patent comprises a heat-resistant backcoat bonded to one
side of a thermally and dimensionally stable substrate, such as PET
film. An ultra thin release layer is provided on the other side of
the substrate, with a pigmented layer then being provided on the
release layer.
[0014] The pigmented layer contains carbon black and resin binder
including polystryrene and polyacrylate resin with various
functional groups such as methacrylic acid to promote adhesion to a
variety of printing substrates. During printing, the pigmented
layer is transferred to the print medium. Formulations for color
ribbons used in applications requiring exterior durability will
likely utilize a resin binder containing only polyacrylate resins
and colored pigments with superior UV light stability. The
formulation of the pigmented layer may also contain various waxes
and other additives in order to achieve targeted viscosity and
physical properties for optimum printing and coating
performance.
[0015] In its final printed form, it is the release layer which if
present functions as the top surface of the printed image. As
described in the '207 patent, the formulation of this layer
contains components that provide for easy release of the pigmented
layer from the substrate and may include such components as
ethylene vinyl acetate copolymer, an .alpha.-olefin maleic
anhydride copolymer and various waxes such as Carnauba wax.
[0016] Thermal transfer printing offers various color options
including the standard cyan, magenta, yellow and black (C-M-Y-K)
process colors as well as a wide range of spot colors including
white, metallics, fluorescents and specialized colors. The ability
to print process colors onto either a clear substrate or on a white
printed background provides the unique combination of vibrant
colors and see-through laminate appearance.
[0017] Thermal transfer printing can be used to print images on a
wide variety of substrates including PET, paper, vinyl, etc.
Accurate color transfer during printing, ink/substrate adhesion and
overall visual appearance are usually dependent upon the surface
characteristics, such as surface smoothness of the print media.
There are a number of companies, including Dunmore Corporation of
Bristol, Pa. who supply print media for use with thermal transfer
printing. Ribbon suppliers such as IIMAK/T2 Solutions of Amherst,
N.Y. will usually provide lists of qualified media to customers. In
many cases there is a proprietary or patented coating on the print
surface of the substrate that provides for improved ink transfer
characteristics. Warranty of outdoor color durability of the
printed image by the ribbon supplier is usually dependent upon use
of qualified media.
[0018] Recent advances in thermal printing technology include the
introduction of lower cost and higher performance color ribbons
with excellent outdoor durability. IIMAK of Amherst, N.Y. makes a
line of high performance resin based color ribbons called
DuraCoat.RTM. (DC-300 series).
[0019] For greater productivity, thermal transfer printing
equipment, such as the Sprinter B Printer manufactured by Matan,
Ltd./Israel, are designed with multiple print heads and ribbons.
Use of multiple print heads and corresponding ribbons require the
use of a substrate with high enough modulus so that color
registration or misaligned color placement is not an issue. For
example, qualified thermal transfer printing media such as white
vinyl needs to be reinforced with a "backing" to minimize this
issue. Commercial printers with width capabilities up to 132 cm.
are available.
[0020] In contrast to the traditional screen print approach for
creation of vibrant colored images, the use of digital printing
provides a very quick means to finished printed images. Use of
digital image manipulation software such as Adobe's Photoshop.RTM.
and/or Illustrator.RTM. in combination with the raster image
processing (RIP) software can complete a full project from design
to finished proof in a matter of hours as compared to days or
longer for the screen print process. The combination of thermal
transfer printing and commercially available graphics software
provides great opportunity for a wide range of customized
aesthetics for use in laminated glass.
[0021] In glass laminate applications involving a glass/plasticized
polyvinyl butyral (plasticized PVB)/glass combination, direct
printing onto a plasticized PVB surface has been demonstrated to be
very difficult with thermal transfer. The poor dimensional
stability of plasticized PVB causes significant problems with color
registration and poor appearance. Surface texture normally present
on commercially available plasticized PVB interlayers for
facilitating effective glass laminate processing also presents a
significant problem in achieving acceptable appearance of the
printed image. For these reasons, accurate transfer of multiple
colors onto plasticized PVB substrates using thermal transfer
technology generally has not been attempted. It would thus be
desirable to develop a laminate composite in which digital color
images are printed onto a sufficiently rigid and smooth substrate
which is then incorporated into the glass/plasticized PVB/glass
laminate.
[0022] Dunmore Corporation produces a clear polyethylene
terephthalate (PET) called Dun-Kote.RTM. DP38 film coated with its
own proprietary coating specifically designed for thermal transfer
printing. However, printing directly onto this substrate and
subsequently incorporating the printed film into a glass laminate
via encapsulation with two layers of plasticized PVB has been found
to yield a laminate with inadequate structural integrity and with
inconsistent printed image quality. These problems have been found
to be the result of poor adhesion between the plasticized PVB and
printed film component--both on the printed and unprinted surfaces
as well as unacceptable interactions between the PVB plasticizer
and the printed side of the PET film. It would thus be desirable to
develop a laminate composite that provides a means for
incorporation of digitally printed color images into
glass/plasticized PVB/glass laminates for customized
applications.
SUMMARY OF THE INVENTION
[0023] The intent of this invention is to achieve a glass laminate
with an encapsulated digitally printed image that has overall
performance characteristics including penetration resistance,
optical quality and durability equivalent to a conventional
glass/plasticized PVB/glass laminate. Because of the well
recognized barrier characteristics of PET film, use of a second PET
film component that is laminated to the printed PET film avoids any
interaction between the PVB plasticizer and the print media coating
or ink layers.
[0024] One embodiment of this invention is directed to an
interlayer for laminated glass, the interlayer comprising a
polymeric support film supporting at least one color image; a
polymeric film bonded to the polymeric support film, such that the
color image is between the polymeric support film and the polymeric
film; a first adhesive layer bonded to the polymeric support film;
and a second adhesive layer bonded to the polymeric film.
[0025] Another embodiment of this invention is directed to a
plastic composite comprising color images printed onto a
polyethylene terephthalate (PET) substrate using digital printing
technology. The PET layer is then bonded to a second PET layer
using a thermally activated adhesive, preferably ethylene vinyl
acetate copolymer (EVA). The bonded PET layers are then disposed
between two layers of plasticized PVB, forming the plastic
composite. The plastic composite can then be placed between two
sheets of glass forming the final laminated glass product.
[0026] A further embodiment of this invention is directed to a
laminated glass composite comprising an interlayer disposed between
two glass sheets, the interlayer comprising a polymeric support
film supporting at least one color image; a polymeric film bonded
to the polymeric support film, such that the color image is between
the polymeric support film and the polymeric film; a first adhesive
layer bonded to the polymeric support film; and a second adhesive
layer bonded to the polymeric film.
[0027] A further embodiment of this invention is directed to an
interlayer comprising a polymeric support film supporting at least
one color image; a polymeric film bonded to the polymeric support
film, such that the color image is between the polymeric support
film and the polymeric film; wherein the interlayer is used in a
glass laminate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1 shows one embodiment of the laminate of the present
invention.
[0029] FIG. 2 is a nip-roll press bonding for forming plasticized
PVB-PET-PET-plasticized PVB laminate.
[0030] FIG. 3 is a cross sectional view of the test fixture used
for compressive shear measurements.
DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS
[0031] The invention disclosed herein describes an interlayer for
use in glass laminates. One embodiment of the present invention is
shown in FIG. 1. The interlayer (2) comprises a printed composite
structure (18) that itself comprises a polymeric support film (16)
having images (13) printed thereon bonded with an adhesive (12) to
a protective polymeric film (14). This printed composite structure
(18) is disposed between two adhesive layers (8, 10) to form the
resultant interlayer (2). The interlayer can then be disposed
between two sheets of glass (4, 6), thereby forming the final glass
laminate product.
[0032] In one embodiment of the present invention, an image is
printed onto a polymeric support film and coated with a polymer
film to improve its ink transfer characteristics. Alternatively, an
image may be printed onto an image layer that is supported by the
polymeric support film. An image can be a logo, symbol, geometric
pattern, photograph, alphanumeric characters or combinations
thereof. The term "color" includes all colors as well as black and
white.
[0033] The thickness of the polymeric support film is preferably 25
to 250 micrometers. The polymeric support film of the present
invention should have properties to maintain its integrity during
handling and deposition of the image onto its surface, as well as
during subsequent bonding and laminating steps. Furthermore, the
polymeric support film should have properties sufficient to be an
integral part of the final safety-glazing product. To satisfy such
performance requirements, the polymeric support film should be
optically transparent (i.e. objects adjacent one side of the layer
can be comfortably seen by the eye of a particular observer looking
through the layer from the other side). The polymeric support film
preferably has, at minimum, an equal to or greater, preferably
significantly greater, tensile modulus than that of the outside
adhesive layers.
[0034] Among thermoplastic materials having the desired physical
properties for use as the polymeric support film are nylons,
polyurethanes, polyacrylates, polyesters, polycarbonates, cellulose
acetates and triacetates, vinyl chloride polymers and copolymers
and the like. Most preferred is polyethylene terephthalate (PET).
Preferably, the PET is biaxially stretched to improve strength and
is also heat stabilized to provide low shrinkage characteristics
when subjected to elevated temperatures (i.e. less than 2%
shrinkage in both directions after 30 minutes exposure at
150.degree. C.). The tensile modulus (at 21-25.degree. C.) of PET
is about 10.sup.10 Pa as compared with about 10.sup.7 Pa for
plasticized PVB of the type used in safety glazings.
[0035] The alternative image layer onto which an image may be
printed is a polymeric film having a non-critical thickness,
preferably 0.1 mm to about 1.5 mm. This image layer should have
properties to maintain its integrity during handling and deposition
of the image onto its surface, as well as during subsequent bonding
and laminating steps. Furthermore, the image layer should have
properties sufficient to be an integral part of the final
safety-glazing product. To satisfy such performance requirements,
the image layer should be optically transparent (i.e. objects
adjacent one side of the layer can be comfortably seen by the eye
of a particular observer looking through the layer from the other
side).
[0036] Among thermoplastic materials having the desired physical
properties for use as the image layer are polyvinyl butyral,
nylons, polyurethanes, polyacrylates, polyesters, polycarbonates,
cellulose acetates and triacetates, vinyl chloride polymers and
copolymers and the like. Most preferred is polyvinyl butyral
(PVB).
[0037] Merely adhering the printed polymeric support film to two
adhesive layers, such as plasticized polyvinyl butyral, such as is
commonly done in the glass laminate industry, does not appear to
provide for a stable laminate composite structure. The polyacrylate
resin binder typically used for the ink layer of the thermal
transfer ribbons seems to interact with common plasticizers used in
commercially available plasticized PVB interlayers (glycol esters,
adipate esters, etc.). This interaction may result in significant
changes in laminate appearance and interply adhesion as well as
compromises in long term laminate durability.
[0038] By introducing a polymeric film to cover the printed surface
of the polymeric support film, which is very impervious to most of
these common plasticizers, the interaction between the plasticized
PVB and polyacrylate resin or any proprietary thermal transfer
coating is virtually eliminated. This polymeric film preferably has
a thickness of around 10 to 125 micrometers. If such a polymeric
film is not used, it is also possible for there to be significant
interactions between the proprietary coatings used on the thermal
transfer print media and the adhesive layer. Similar consequences
as those described in the preceding paragraph are possible and not
desirable. For inkjet formulations, the polymeric film helps bond
the printed support film to the adhesive layer(s) as well as acting
as a barrier to migration of printed ink components,(e.g., carrier
solvents, etc) into the adhesive layers which can significantly
affect the integrity of the glass laminate. It also acts as a 2-way
barrier by protecting the print from interaction with the adhesive
layer components, such as plasticizer contact as described
above.
[0039] One aspect of the present invention, though, is to achieve
adequate adhesion between the polymeric film and the polymeric
support film in order to achieve acceptable long term laminate
integrity. In the preferred embodiment of the present invention,
the polymeric film covering the printed surface is a second
polymeric support film, such as a second PET layer. In another
embodiment, the polymeric support film comprising the color image
is coated with reactive mixture that is cured by ultraviolet light
or heat to form a polymeric film that serves as the protective
layer. Possible coatings could include epoxy, polyester,
polyacrylate or polyurethane compositions. In another embodiment,
the polymer film is coated with a water emulsion or solvent based
polymer in which the water or solvent is removed to form a
polymeric film. Possible coatings could include epoxy, polyester,
polyacrylate or polyurethane compositions.
[0040] In the graphics industry use of an "overlay" film to provide
protection of printed images is well known and practiced widely.
The technology usually involves the use of a clear plastic film
such as PET film coated with either a pressure activated acrylic
adhesive or a heat activated adhesive such ethylene vinyl acetate
copolymer. In the case of the PET overlay film with the pressure
activated adhesive there is usually a silicone release liner mated
to the adhesive surface which prevents blocking of the film in roll
form and which must be removed prior to use.
[0041] With properly selected chemistry use of thermally activated
adhesives commonly result in robust adhesion between PET layers.
Use of ethylene vinyl acetate (EVA) copolymer provides acceptable
peel and compressive shear adhesion properties that can result in
excellent laminate integrity. Use of EVA copolymer adhesive will
result in penetration resistance and other laminate performance
properties that will be equivalent or superior to standard
glass/plasticized PVB/glass laminates. Furthermore, the use of a
thermally activated adhesive system to combine the PET-PET
components is likely to provide for significant processing
advantages over acrylic pressure sensitive adhesives, for example,
during the manufacturing process of the plasticized
PVB/PET-PET/plasticized PVB composite structure. With the use of a
polymeric film comprising a PET overlay film coated with a heat
activated adhesive there is normally no need to provide a separate
release liner if an adhesive with proper tacticity has been
selected. Other thermally activated adhesives such as polyurethane
thermoplastic adhesives can also be used as well.
[0042] While EVA copolymer/PET composites have been used
extensively as protective overlays of printed materials which are
combined using heat/pressure lamination, it is normally not used in
the manufacture of glass laminates which require much longer (45-60
minutes vs. 10-20 seconds) and higher temperature (135.degree. C.
vs. 65-95.degree. C.) processing conditions. For successful glass
lamination the EVA copolymer adhesive composition (i.e. % vinyl
acetate content) and thickness must be carefully selected in order
to minimize haze formation caused by crystallization and less than
optimum adhesion. Higher vinyl acetate content allows for greater
adhesion between layers and lower haze levels. At vinyl acetate
contents above 28% issues with roll blocking of the EVA/PET
composite will cause processing difficulties during the overlay
lamination step. Use of thinner layers of EVA and/or multi-layer
co-extruded EVA structures can be used to achieve acceptable
adhesion and haze results.
[0043] Typical heat/pressure laminating equipment as manufactured
by companies such as General Binding Corporation are useful with
the present invention. This type of equipment typically employs a
supply roll of overlay film (heat activated adhesive+clear polymer
film) that can be preheated using heated rolls or infra-red heating
elements prior to combination with the printed film using nip roll
pressure lamination. Such process equipment is normally configured
with line speed, heating and nip roll pressure controls to provide
for a resultant two ply laminate with excellent transparency which
is indicative of no air entrapment between the layers and adequate
flow of the adhesive.
[0044] As with the conventional use of this laminating technology
in the graphic arts industry it is important to operate in a clean
environment to minimize any contamination that might be entrapped
between the polymeric support film and polymeric film and cause
significant optical defects. Use of PET films with antistatic
coatings is a preferred embodiment of the current invention and its
value is derived from the reduction in airborne contamination and
consequential improvement in optical quality.
[0045] After the printed polymeric support film is adhered to the
second polymeric film, the combined structure is then disposed
between two adhesive layers. Adhesive layers that can be utilized
with the present invention include polyurethane, ethylene vinyl
acetate copolymer, plasticized polyvinyl chloride as well as other
elastomeric polymers with energy absorbing properties and surface
chemistry to provide adequate adhesion to glass and the polymeric
support film and polymeric film layers. The preferred adhesive
layer of the present invention is plasticized PVB.
[0046] The outer surface layers of the combined polymeric support
and polymeric films in contact with the adhesive layers must be
appropriately coated and/or treated to achieve adequate adhesion
and laminate integrity. Preferred techniques are chemical
modification of the outer polymeric support and polymeric films by
flame treatment, chemical oxidation, corona discharge, carbon
sputtering, plasma treatment in vacuum or in air, application of an
adhesive, or other treatments well known to those of ordinary skill
in the art.
[0047] PVB resin is produced by known aqueous or solvent
acetalization processes reacting PVOH with butyraldehyde in the
presence of acid catalyst, followed by neutralization of the
catalyst, separation, stabilization and drying of the resin. It is
commercially available from Solutia, Inc. as Butvar.RTM. resin. PVB
resin typically has a weight average molecular weight greater than
70,000, preferably about 100,000 to 250,000, as measured by size
exclusion chromatography using low angle laser light scattering. On
a weight basis PVB resin typically comprises less than 22%,
preferably about 17 to 19% hydroxyl groups calculated as polyvinyl
alcohol (PVOH); up to 10%, preferably 0 to 3% residual ester
groups, calculated as polyvinyl ester, e.g. acetate, with the
balance being acetal, preferably butyraldehyde acetal, but
optionally including a minor amount of acetal groups other than
butyral, for example 2-ethyl hexanal as disclosed in U.S. Pat. No.
5,137,954.
[0048] The PVB resin of the sheet is typically plasticized with
about 15 to 50 and more commonly 25 to 45 parts plasticizer per
hundred parts of resin. Plasticizers commonly employed are esters
of a polybasic acid or a polyhydric alcohol. Suitable plasticizers
are triethylene glycol di-(2-ethylbutyrate), triethyleneglycol
di-(2-ethylhexanoate), tetraethyleneglycol diheptanoate, dihexyl
adipate, dioctyl adipate, mixtures of heptyl and nonyl adipates,
dibutyl sebacate, polymeric plasticizers such as the oil-modified
sebacic alkyds, and mixtures of phosphates and adipates such as
disclosed in U.S. Pat. No. 3,841,890 and adipates and alkyl benzyl
phthalates as disclosed in U.S. Pat. No. 4,144,217. Also mixed
adipates made from C.sub.4 to C.sub.9 alkyl alcohols and cyclo
C.sub.4 to C.sub.10 alcohols as disclosed in U.S. Pat. No.
5,013,779. C.sub.6 to C.sub.8 adipate esters such as hexyl adipate
are preferred plasticizers. A more preferred plasticizer is
triethylene glycol di-(2-ethylhexanoate).
[0049] It is also desirable to incorporate a UV absorber into the
plasticized PVB layers. One such UV absorber is disclosed in U.S.
Pat. No. 5,618,863, the contents of which are incorporated herein
by reference. The amount of UV absorber added to the plasticized
PVB can vary and is generally from 0.1 to 1.0 part per 100 parts
PVB polymer. Sandwiching the printed laminate composite between two
plasticized PVB adhesive layers containing a UV absorber eliminates
the need to include these expensive components in the PET print
media or PET overlay film. Because almost all commercially
available PET films do not contain UV absorbers, they are subject
to significant UV degradation resulting in embrittlement of the
film unless properly protected. In the preferred case when PET film
is used for the printing media or overlay film, addition of UV
absorber to the plasticized PVB layers is essential so that there
is no degradation of the PET polymer. Furthermore, the addition of
UV absorber in the plasticized PVB layers provides for improved
light stability of the colorants in the printed layer.
Alternatively, a UV absorber could be added to the PET or other
selected polymeric support films.
[0050] In addition to plasticizer, UV absorber and adhesion control
agent, the plasticized PVB layers may contain other performance
enhancing additives such as pigments or dyes for coloring all or
part of the sheet, antioxidants and the like. For example, one of
the PVB layers could be a white color with low visible
transmittance PVB layer which can increase the vibrancy of colors
on the printed PET layer.
[0051] Plasticized PVB sheet at a non-critical thickness of about
0.38 to 1.5 mm is formed by mixing resin and plasticizer plus
additives and preferably (in commercial systems) extruding the
mixed formulation through a sheet die, i.e., forcing molten,
plasticized PVB through a horizontally long vertically narrow die
opening substantially conforming in size to the sheet being formed.
Roughness of the surface of the sheet is usually produced through a
phenomenon known to those skilled in the art as melt fracture and
such desired characteristics can be derived by design of the
extrudate die opening as shown, for example, in FIG. 4 of U.S. Pat.
No. 4,281,980. Other known techniques for producing a rough surface
on one or more sides of an extruding sheet involve specifying or
controlling one of the following: polymer molecular weight
distribution, water content and temperature of the melt. These
techniques are disclosed in U.S. Pat. Nos. 2,904,844; 2,909,810;
3,994,654; 4,575,540 and European Patent No. 0185,863. Embossing of
the sheet downstream of the die can also be used to produce the
desired surface roughness. Examples of embossed plasticized PVB
sheets with regular patterned surfaces are described in U.S. Pat.
Nos. 5,425,977 and 5,455,103. This plasticized PVB surface
roughness is needed to facilitate the de-airing of the
glass/plasticized PVB interface and is completely eliminated during
subsequent autoclave lamination. The final laminate of the present
invention is formed using processes known in the art.
[0052] Referring to FIG. 2, a process will be described for forming
the full printed laminate composite 2 for use in a safety glazing
such as a vehicle or building window, skylight, sunroof or the
like. FIG. 2 illustrates a nip roll press-bonding system for
encapsulating the printed laminate layer 18 within plasticized PVB
layers 8 and 10. The printed laminate layer 18 from roll 62 is
passed over tension roll 64 and subjected to moderate surface
heating in stations 66 positioned to gently heat either printed
laminate layer 18, plasticized PVB sheets 8 and 10, or both.
Heating is to a temperature sufficient to promote temporary fusion
bonding in that the thermally softened surfaces of layers 8 and 10
become tacky. When the polymeric support layers of printed laminate
layer 18 are the preferred biaxially oriented polyethylene
terephthalate, suitable temperatures are from about 30.degree. C.
to about 120.degree. C., with the preferred surface temperature
reaching about 50.degree. C.
[0053] Printed laminate layer 18 and plasticized PVB layers 8 and
10, each having roughened de-airing surfaces, are directed into the
laminating nip between oppositely rotating press rolls 68a, 68b
where the three layers are merged together. This expels the air
between the layers and this process step is critical because it is
essential to remove as much air as possible from between the
layers. The result of this merging is the encapsulation of printed
laminate layer 18 within plasticized PVB layers 8 and 10 to form
the lightly bonded laminate 2 of FIG. 1, without flattening the
outer unbonded de-airing surfaces of layers 8 and 10. Layers 8 and
10 are supplied from rolls 72a, 72b and a tension roll 73 can be
included in the plasticized PVB layer supply line. If desired,
press rolls 68a, 68b can be optionally heated to promote bonding.
Bonding pressure exerted by press rolls 68a, 68b can be varied
depending on the carrier film material chosen and bonding
temperature employed but generally will range from about 0.7 to 5
kg/sq cm, preferably about 1.8 to 2.1 kg/sq cm. The tension of
laminate 2 is controlled by passage over idler roll 74. Typical
line speeds through the FIG. 2 assembly are from 1.5 to 10
m/min).
[0054] The laminate of the present invention will most commonly be
disposed between sheets of glass, preferably a pair of matching
float glass sheets. The glass sheets can be any combination of any
types of glass, including both clear glass and tinted glass, and
including annealed, heat strengthened or tempered glass. The
composite laminate of the present invention has the advantage that
it can be used in the same manner and laminated employing the same
equipment as that employed in forming conventional safety glass
laminates, for example, process forming a safety glass laminate
containing a single layer plasticized PVB safety film. The typical
commercial safety glass lamination process comprises the following
steps:
[0055] (1) hand assembly of the two pieces of glass and composite
laminate;
[0056] (2) passing the assembly through a pressure nip roll at room
temperature to expel trapped air;
[0057] (3) heating the assembly via IR radiant or convective means
for a short period, typically until reaching a glass surface
temperature of about 100.degree. C.;
[0058] (4) passing the hot assembly through a second pair of nip
rolls to give the assembly enough temporary adhesion to seal the
edge of the laminate and allow further handling and
[0059] (5) autoclaving the assembly typically at temperatures
between 130 to 150.degree. C. and pressures between 1050 to 1275
kN/sq. m for about 30 to 90 minutes.
[0060] Other means for use in de-airing of the plasticized
PVB/glass interfaces (steps 2-4) known in the art and are
commercially practiced include vacuum bag and vacuum ring processes
in which vacuum is utilized to remove the air.
[0061] Acceptable end use performance requirements of a glass
laminate include maintenance of structural integrity (that is, no
interfacial separations) when subjected to external forces such as
those imposed by wind, temperature, etc. In addition, the
nonplanarity of heat strengthened or tempered glass if used for the
fabrication of glass laminates can result in a force that may
result in the separation of one or more layers. For one of the
embodiments of the current invention there are at least six
additional interfaces (e.g., plasticized PVB/PET, PET/thermal
transfer coating, thermal transfer coating/ink layer, ink layer/EVA
adhesive, EVA adhesive/PET, PET/plasticized PVB) as compared to a
standard glass/plasticized PVB/glass laminate that need to be
considered. In order to avoid issues with laminate integrity it is
essential that the interfacial adhesion of all surfaces within a
glass laminate meet a minimum requirement. Measurement of the
compressive shear strength of a laminate provides an adhesion
measurement of the weakest interface. This result can be used as
means to determine laminate integrity and the potential for
interfacial delamination during installed use.
[0062] The compressive shear strength of a laminate is measured
using the test method outlined below and shown in FIG. 3. Glass
laminates for evaluation are prepared using conventional lamination
methods which have been described in a previous section. Thickness
of the glass layers used for the laminates is selected such that
during testing, the plastic/glass interfaces are able to move
freely within the test fixture as shown in the FIG. 3. For each
laminate type under evaluation a series of at least 6 circular test
specimens with a diameter of 30 mm are cut from a larger piece of
glass laminate using rotary diamond core drill with water cooling.
Water cooling is adjusted to avoid excessive heating of the
laminate and care is taken to minimize glass chipping. After the
test specimens have been cut, they are conditioned overnight at 21
to 23.degree. C. prior to testing.
[0063] To initiate the testing, the circular test specimen is
placed into the recessed circular area of the stationary lower half
of the test fixture after which the upper half of the test fixture
is mated with the lower half. The assembled test fixture with
loaded test specimen is then inserted into a testing apparatus such
as an Alpha Technologies T20 Tensometer in which a crosshead can
apply a measured force to the movable top surface of the test
fixture. Once the crosshead makes contact with the top surface of
the test fixture, the crosshead is moved at a constant rate of 3.2
mm/min and the maximum force required to shear the sample is
determined. The interface at which failure occurs should be noted
to identify the weakest interface. The measured force is then
converted in compressive shear strength by dividing it by the
cross-sectional area of the test specimen. Minimum compressive
shear strength for laminates with adequate integrity has been
estimated to be approximately 8 MPa.
[0064] The 90 degree peel adhesion test method measures the
adhesive bond strength between plasticized PVB and PET film.
Special test laminates (6.4 cm width.times.17.1 cm length)
containing the PET film to be tested and Saflex.RTM. RB41 a
commercially available plasticized PVB sheet from Solutia Inc. are
prepared using modified laminating techniques previously described
by substituting the PET test film for one glass piece of a standard
glass/plasticized PVB/glass laminate. The thickness of the
plasticized PVB layer is 0.76 mm. Glass thickness while not an
important factor is usually in the range of 2.0 to 3.0 mm.
Thickness of the PET to be tested ranges from 50-175 micrometers.
In order to ensure that the adhesion between the glass and the
plasticized PVB layer is greater than the adhesion between the PET
and plasticized PVB layer, the plasticized PVB film is dried at
70.degree. C. for one hour prior to assembly.
[0065] The glass/plasticized PVB/PET laminates are prepared by hand
assembly of the individual components. It is also useful to insert
a small (2.5 cm.times.6.4 cm) piece of thin piece (about 12
micrometers) PET film having very low adhesion to plasticized PVB
between the plasticized PVB and PET layers at the point where the
peel test specimen is scored and broken (see below) in order to
facilitate the initial peeling process otherwise it may be
difficult to initiate the separation of the plasticized PVB and PET
layers.
[0066] Two such assembled laminates are then placed with PET
surfaces in contact with each other and passed through deairing
rolls that have the gap adjusted to apply a required amount of
pressure and effectively expel excessive air located between the
various layers. The laminates are then placed individually into a
convection air oven at 105.degree. C. for 10 minutes. The hot
laminates are again coupled in pairs (with a paper separator if
needed to avoid adhesion between the PET layers) and passed through
the nip rolls as before. These laminates are then autoclaved at a
pressure of 1275 kN/sq m using an autoclave cycle with a 20 minute
hold time at 143.degree. C.
[0067] After autoclaving is completed, two cuts parallel to the
length of the laminate at a distance of 4 cm from each other are
made through the PET layer only using a razor blade or other
similar instrument. The surface is then scored on the glass side
and broken parallel to width dimension of the laminate at a
position approximately 4 cm from the end of the laminate. From the
glass side of the laminate, a cut is made through the plasticized
PVB layer at the glass break to allow the PET film to be peeled
from the plasticized PVB layer. The outside edge of the PET film on
each side of the 4 cm width strip is cut at the glass break. At
least three samples for each PET film type are tested per reported
value.
[0068] Before conducting the actual peel test, the samples are
conditioned overnight at 21.degree. C. During peel testing, the
glass/plasticized PVB/PET test specimen is positioned in the grips
of a peel tester (cross-head speed of 12.7 cm per min) which is
configured to peel the PET film from the plasticized PVB surface at
a 90 degree angle. The force necessary to separate the PET film
from the plasticized PVB surface is measured and the average of the
various recorded peaks is determined. Peel adhesion is then
calculated by dividing the measured force by the 4 cm width of the
test strip. Minimum peel adhesion for laminates with adequate
integrity has been estimated to be approximately 4 N/cm, with
preferred embodiments having a peel adhesion of about 8 N/cm.
[0069] When performing the five pound (2.27 kg) ball drop test, a
series of glass laminates having dimensions of 30.5 cm.times.30.5
cm are prepared using standard autoclave lamination techniques
described previously. At least 6 glass laminates, preferably 12
glass laminates are required to measure the penetration resistance.
The prepared glass laminates are individually positioned in a
support frame as described in the ANSI/SAE Z26.1 automotive test
code. While at a constant temperature of 21.degree. C..+-.2.degree.
C., a five pound (2.27 kg) spherical steel ball is dropped onto the
center of the laminate from a specified height that will result in
penetration of the laminate. Two spaced magnetic coils that are
coupled and positioned beneath the test laminate measure the time
for the steel ball to traverse the distance between the coils. This
measured time is then converted into the ball velocity after
lamination penetration. The velocity of the ball as it strikes the
glass surface is also calculated. The loss in kinetic energy of the
ball as it penetrates the laminate is then converted into break
height. Measured Mean Break Height is the average break height in
meters of at least 6 ball drops in which both glass laminate
failure and ball penetration occurs.
[0070] Finally, laminate haze is measured following ASTM D1003-00
(Test Method for Haze and Luminous Transmittance/Procedure B) using
a Byk-Gardner TCS Spectrophotometer.
[0071] The 0 degree Pummel Adhesion Test has been a standard
Solutia procedure for over 30 years. It measures the adhesion level
of glass to the PVB adhesive layer in a laminate construction. The
PVB layer to glass adhesion has a large effect on the impact
resistance and long term stability of glass/PVB structures.
[0072] A laminate is conditioned to 0 F. degrees and pummeled with
a 1 lb. hammer. The amount of glass remaining on the PVB adhesive
layer is compared to standards and given a 1 to 10 rating.
[0073] The most commonly used method is as follows: 1) Cut the
glass into 15 cm.times.15 cm sections. Then place the specimens in
a cold air cabinet at 0 F. degrees for at least 1 hour. Air
velocity in the cabinet should be a minimum of 100 fpm. The
specimens should be separated to ensure air circulation to all
surfaces. Using heavy cotton gloves, remove one sample at a time
and pummel the specimen using a one-pound hammer and the Solutia
Pummel Box. Specimens should be pummeled immediately after removal
from the conditioning cabinet to obtain accurate results. The
specimen is to be held at a 5 degree angle to the plane of the
pummel plate so that only the edge of the broken glass contacts the
plate. The specimen is then pummeled progressively in 1/2 inch
increments along its bottom 3/4 inch. When this bottom row has been
completely pulverized, the next 3/4 inch is pulverized and so on
until about 1/2 inch remains. The specimen is then turned over and
the pummel is repeated.
[0074] The pummeled samples are allowed to come to room temperature
and condensed moisture is allowed to evaporate until grading
begins. The samples are then compared to the standards. Standards
all have different levels of glass attached to the PVB adhesive
layer which is what is being judged. Both the test sample and one
of the standards are tilted together to catch the light source
reflection which is positioned overhead and in front of the
evaluator. The comparisons are repeated with all the standards
until a match is made. The pummel number is recorded and the sample
is turned over and the opposite side is also rated versus the
existing standards.
[0075] Pummel values are grouped and averaged for like specimens.
Reported values state the average pummel value for the group, the
number of samples in the group and the maximum range of the pummel
adhesion rating for individual surfaces.
EXAMPLES
Example 1
[0076] Dun-Kote.RTM. DP38--a 3 mil high clarity PET film
manufactured by Dunmore Corporation of Bristol, Pa.--having a
proprietary coating for improved performance with thermal transfer
printing was adhesion promoted on the uncoated side via plasma
treatment. Process conditions were employed during the plasma
treatment so that the resultant 90 degree peel adhesion of this
treated surface to Saflex.RTM. plasticized PVB interlayer (RB41)
commercially available from Solutia Inc. after autoclave lamination
was found to be 8 N/cm.
Example 2
[0077] A PET overlay film consisting of 1 mil layer of ethylene
vinyl acetate copolymer containing 28% vinyl acetate was coated
onto a 2.65 mil Hostaphan.RTM. 4707 PET film (commercially
available from Mitsubishi Films, Greer, S.C.). The surface of the
PET overlay film coated with the ethylene vinyl acetate copolymer
was not tacky prior to use. The uncoated PET surface of this
PET/EVA overlay film was plasma treated prior to coating. Testing
of the 90 degree peel adhesion of the uncoated PET surface to
standard Saflex.RTM. plasticized PVB (RB41) interlayer after
autoclave lamination was found to be 12 N/cm.
Example 3
[0078] A digital test image was printed onto the coated surface
film from Example 1 using the Matan Sprinter B printer and
Duracoat.RTM.) DC300 series C-M-Y-K ribbons supplied by T2
Solutions of Amherst, N.Y. The resultant test image showed
excellent color and image detail.
Example 4
[0079] The EVA/PET overlay film of Example 2 was heat laminated to
the printed PET film in Example 3 using a conventional heated
roll/pressure nip process configuration. Process conditions were
selected to achieve a final composite appearance with high
transparency and no visible air entrapment.
Example 5
[0080] The printed test image of Example 3 was "hand" encapsulated
with two layers of 0.38 mm standard Saflex.RTM. RB-11 plasticized
PVB interlayer (commercially available from Solutia) and then
laminated with two pieces of 2.3 mm annealed glass to form a
finished glass laminate using conventional nip roll deair/hot tack
and autoclave processing as described previously. Compressive shear
adhesion were measured and found to be low (7 MPa) with failure
observed at the ink/plasticized PVB interface. This low compressive
shear adhesion is considered at an unacceptable level for overall
glass laminate integrity. Significant changes in the visual
appearance of the printed image were also observed after lamination
and were considered unacceptable.
Example 6
[0081] The PET-PET composite of Example 4 was encapsulated with two
layers of 0.38 mm standard Saflex.RTM. plasticized PVB interlayer
(RB11) and then laminated with two pieces of 2.3 mm annealed glass
to form a finished glass laminate using conventional nip roll
deair/hot tack and autoclave processing. Both haze and compressive
shear adhesion were measured and found to be within acceptable
limits as shown below. No changes in the visual appearance or color
of the printed images were observed after lamination.
1 Haze 1.4% Compressive Shear 12.3 MPa
[0082] Mean Break Height (MBH) was tested using the 5 lb.ball drop
test method and found to be greater than 7.6 m which is at least
comparable to an equivalent glass/plasticized PVB/glass
laminate.
Example 7
[0083] A digital test image was printed on the coated side of a
Sentinel Imaging, Graphix brand clear polyester film using an HP
Designjet inkjet printer. An adhesive coating was applied to the
reverse side of the film. The resultant image showed good
appearance and vibrancy.
Example 8
[0084] A digital test image was printed on the coated side of a
Sentinel Imaging, Graphix brand clear polyester film using an HP
Designjet inkjet printer. An adhesive coating was applied to the
reverse side of the film. The resultant image was "hand"
encapsulated with two layers of 0.38 mm standard Saflex.RTM. RB-11
plasticized PVB interlayer (commercially available from Solutia)
and then laminated with two pieces of 2.3 mm annealed glass to form
a finished glass laminate using conventional nip roll deair/hot
tack and autoclave processing as described previously. Compressive
shear adhesion was measured and found to be low (5 MPa) with
failure observed at the ink/plasticized PVB interface.
Example 9
[0085] The EVA/PET overlay film of Example 2 was heat laminated to
the printed PET film in Example 7 using a conventional heated
roll/pressure nip process configuration. Process conditions were
selected to achieve a final composite appearance with high
transparency and no visible air entrapment.
Example 10
[0086] The PET-PET composite of Example 9 was encapsulated with two
layers of 0.38 mm standard Saflex.RTM. plasticized PVB interlayer
(RB11) and then laminated with two pieces of 2.3 mm annealed glass
to form a finished glass laminate using conventional nip roll
deair/hot tack and autoclave processing. Both haze and compressive
shear adhesion were measured; haze was found to be within
acceptable limit and the compressive shear measurement was 11.2
MPa. No changes in the visual appearance or color of the printed
images were observed after lamination.
Example 11
[0087] A digital test image printed onto an opaque white polyester
backlit film from Circle Graphics Co. using an inkjet printer known
as Purgatory, resulted in a 2-way signage effect in a window type
configuration. This printed support film was then bonded to the
polymeric film in the same processes as described above and had a
compressive shear result of 9.9 MPa. When the polymeric film was
not overlayed onto the print as described in Example 8, the
compressive shear measurement was 5.2 MPa.
Example 12
[0088] A digital test image printed onto plasticized polyvinyl
butyral using a Vutek UltraVu 3360 inkjet printer and Inkware ink
formulation. This printed test image was "hand" encapsulated with
two layers of 0.38 mm standard Saflex.RTM. RB-11 plasticized PVB
interlayer (commercially available from Solutia) and then laminated
with two pieces of 2.3 mm annealed glass to form a finished glass
laminate using conventional nip roll deair/hot tack and autoclave
processing as described previously. Peel adhesion results at the
printed PVB/PVB interface ranged from 1 to 6 N/cm depending on the
dominant color of the image and the percent of color coverage. The
glass to adhesive layer PVB adhesion level varied between 0 to 6
pummel units depending on the color of the print. This strongly
hints at migration of elements from the color inkjet ink
formulation through the structure to the outermost (glass/adhesive
PVB) interface. The results also indicate that the resulting
laminate will not have the integrity to be used in many
applications where traditional safety glass is used.
Example 13
[0089] Example 12 was repeated using a Mitsubishi 4707 PET
polymeric film as the polymeric overlay film as well as the
polymeric support film. The adhesion of the glass to the adhesive
PVB layer measured 5.0 pummel units which did not vary from a
targeted level of 5.0+/-1.0 pummel units. This result allows the
laminate performance to be predicted and used in a safety glass
application.
[0090] The preceding description is set forth for purposes of
illustration only and is not to be taken in a limited sense.
Various modifications and alterations will be readily apparent to
persons skilled in the art. It is intended, therefore, that the
foregoing be considered as exemplary only and that the scope of the
invention be ascertained from the following claims.
* * * * *