U.S. patent application number 09/896410 was filed with the patent office on 2001-12-13 for sealant composition, article including same, and method of using same.
This patent application is currently assigned to 3M Innovative Properties Company. Invention is credited to Boettcher, Robert J., George, Clayton A., Johnson, Michael A..
Application Number | 20010051260 09/896410 |
Document ID | / |
Family ID | 25476448 |
Filed Date | 2001-12-13 |
United States Patent
Application |
20010051260 |
Kind Code |
A1 |
Johnson, Michael A. ; et
al. |
December 13, 2001 |
Sealant composition, article including same, and method of using
same
Abstract
A multi-layer article which may be provided in the form of a
tape comprises a conformable, compressible, melt flow-resistant
core layer having first and second major surfaces, a sealant layer
on the first major surface of the core layer, and optionally a
bonding layer on the second major surface of the core layer. The
sealant layer and the bonding layer each have a surface available
for contacting a separate substrate. Various thermoset and foam
core layers are disclosed as are thermosettable and thermoplastic
sealant layers. The articles are useful for sealing two substrates
together, particularly where one of the substrates is glass. Thus,
the articles are especially adapted for sealing motor vehicle
windshields to a frame. Various assemblies and methods for
producing the same are also described.
Inventors: |
Johnson, Michael A.;
(Stillwater, MN) ; George, Clayton A.; (Afton,
MN) ; Boettcher, Robert J.; (Stillwater, MN) |
Correspondence
Address: |
Office of Intellectual Property Counsel
3M Innovative Properties Company
PO Box 33427
St. Paul
MN
55133-3427
US
|
Assignee: |
3M Innovative Properties
Company
|
Family ID: |
25476448 |
Appl. No.: |
09/896410 |
Filed: |
June 29, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09896410 |
Jun 29, 2001 |
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08941430 |
Sep 30, 1997 |
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6284360 |
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Current U.S.
Class: |
428/317.7 ;
428/308.8; 428/314.4; 428/317.1; 428/319.3; 428/426; 428/430;
428/457; 428/458 |
Current CPC
Class: |
B32B 2307/54 20130101;
C09J 7/35 20180101; B32B 5/18 20130101; B32B 2375/00 20130101; B32B
2266/08 20130101; B32B 27/08 20130101; Y10T 428/249959 20150401;
Y10T 428/249991 20150401; B32B 27/40 20130101; Y10T 428/31678
20150401; C09J 7/38 20180101; Y10T 428/31616 20150401; Y10T
428/249985 20150401; B32B 27/18 20130101; B60J 10/70 20160201; C09J
7/26 20180101; Y10T 428/249976 20150401; Y10T 428/31681 20150401;
C03C 27/048 20130101; C09J 7/22 20180101; Y10T 428/249982 20150401;
B32B 2605/006 20130101; B32B 7/12 20130101 |
Class at
Publication: |
428/317.7 ;
428/308.8; 428/314.4; 428/317.1; 428/319.3; 428/426; 428/430;
428/457; 428/458 |
International
Class: |
B32B 007/12 |
Claims
What is claimed is:
1. An article comprising (a) a conformable, compressible, melt
flow-resistant foam core layer having first and second major
surfaces, and (b) a thermosettable sealant layer on said first
major surface of said core layer, said sealant layer having a
surface available for contacting a substrate.
2. An article according to claim 1 wherein said thermosettable
sealant layer comprises a curing agent.
3. An article according to claim 2 wherein said curing agent
comprises a photo-active curing agent.
4. An article according to claim 2 wherein said curing agent
comprises a thermally active curing agent.
5. An article according to claim 1 wherein said thermosettable
sealant layer is a blend comprising (a) an epoxy resin, (b) a resin
selected from the group consisting of polyacrylates,
semi-crystalline polyesters, and combinations thereof, and (c) a
curing agent selected from the group consisting of (i) thermally
activated agents characterized by a thermal activation temperature
and (ii) photo-active curing agents characterized by a thermal
decomposition temperature.
6. An article according to claim 1 wherein said thermosettable
sealant layer substantially retains it shape when heated to a
temperature greater than the softening temperature of said
composition, but less than about 200.degree. C., until acted upon
by an external force other than gravity.
7. An article according to claim 1 wherein said thermosettable
sealant layer includes a curing agent selected from the group
consisting of (a) thermally activated agents characterized by a
thermal activation temperature and (b) photo-active curing agents
characterized by a thermal decomposition temperature, said sealant
composition characterized in that prior to cure, said composition
substantially retains its shape when heated to a temperature
greater than the softening temperature of said composition, but
less than (a) the thermal activation temperature of said curing
agent, where said curing agent is a thermally activated curing
agent, or (b) the thermal decomposition temperature of said curing
agent, where said curing agent is a photo-active curing agent,
until acted upon by an external force other than gravity.
8. An article according to claim 1 wherein said thermosettable
sealant layer comprises a blend of an epoxy resin, a
semi-crystalline polyester, and a curing agent selected from the
group consisting of (a) thermally activated agents characterized by
a thermal activation temperature and (b) photo-active curing agents
characterized by a thermal decomposition temperature, said sealant
composition characterized in that prior to cure, said sealant
composition substantially retains its shape when heated to a
temperature greater than the melting temperature of said polyester
but less than (a) the thermal activation temperature of said curing
agent, where said curing agent is a thermally activated curing
agent or (b) the thermal decomposition temperature of said curing
agent, where said curing agent is a photo-active curing agent,
until acted upon by an external force other than gravity.
9. An article according to claim 8 wherein prior to cure, said
thermosettable sealant composition substantially retains its shape
when heated to a temperature greater than the melting temperature
of said polyester, but less than about 200.degree. C., until acted
upon by an external force other than gravity.
10. An article according to claim 8 wherein said curing agent
comprises a photo-active curing agent.
11. An article according to claim 1 wherein said sealant layer
comprises a moisture-curable polyurethane.
12. An article according to claim 1 wherein said core layer has an
ultimate tensile strength no greater than the ultimate tensile
strength of said thermosettable sealant layer.
13. An article according to claim 1 wherein said core layer
comprises a foam.
14. An article according to claim 13 wherein said core layer
comprises a closed cell foam.
15. An article according to claim 1 wherein said core layer
comprises a foam selected from the group consisting of acrylic,
urethane and polyolefin foams.
16. An article according to claim 1 wherein said core layer
comprises a pressure sensitive adhesive.
17. An article according to claim 1 further comprising a bonding
layer provided on the second major surface of said core layer.
18. An article according to claim 17 wherein said sealant layer and
said bonding layer are thermally insulated from each other.
19. An article comprising (a) a conformable, compressible, melt
flow-resistant thermoset core layer having first and second major
surfaces, and (b) a thermosettable sealant layer on said first
major surface of said core layer, said sealant layer having a
surface available for contacting a substrate.
20. An article according to claim 19 wherein said thermosettable
sealing layer includes a photo-active curing agent.
21. An article according to claim 19 wherein said thermosettable
sealing layer comprises a thermally active curing agent.
22. An article according to claim 19 wherein said thermosettable
sealant layer is a blend comprising (a) an epoxy resin, (b) a resin
selected from the group consisting of polyacrylates,
semi-crystalline polyesters, and combinations thereof, and (c) a
curing agent selected from the group consisting of (i) thermally
activated agents characterized by a thermal activation temperature
and (ii) photo-active curing agents characterized by a thermal
decomposition temperature.
23. An article according to claim 19 wherein said thermosettable
sealant layer substantially retains it shape when heated to a
temperature greater than the softening temperature of said
composition, but less than about 200.degree. C., until acted upon
by an external force other than gravity.
24. An article according to claim 19 wherein said core layer has an
ultimate tensile strength no greater than the ultimate tensile
strength of said thermosettable sealant layer.
25. An article according to claim 19 wherein said core layer
comprises a closed cell foam.
26. An article according to claim 19 wherein said core layer
comprises a pressure sensitive adhesive.
27. An article according to claim 19 further comprising a bonding
layer provided on the second major surface of said core layer.
28. An article comprising (a) a conformable, compressible, melt
flow-resistant core layer having first and second major surfaces,
and (b) a thermoplastic sealant layer on said first major surface
of said core layer, said sealant layer having a surface available
for contacting a substrate, and further wherein said sealant layer
is formed from a thermoplastic polymer selected from the group
consisting of polyurethanes, polyesters, polyaromatic-containing
block copolymers, and silicones.
29. An article according to claim 28 wherein said core layer has an
ultimate tensile strength no greater than the ultimate tensile
strength of said thermoplastic sealant layer.
30. An article according to claim 28 wherein said core layer
comprises a foam.
31. An article according to claim 30 wherein said core layer
comprises a pressure sensitive adhesive foam.
32. An article according to claim 28 further comprising a bonding
layer provided on the second major surface of said core layer.
33. An article comprising (a) a conformable, compressible, melt
flow-resistant thermoset core layer having first and second major
surfaces, (b) a sealant layer on said first major surface of said
core layer and having a surface available for contacting a first
substrate, and (c) a thermosettable bonding layer on said second
major surface of said core layer and having a surface available for
contacting a second substrate.
34. An article comprising (a) a conformable, compressible, melt
flow-resistant core layer comprising a closed cell foam having
first and second major surfaces and (b) a sealant layer provided on
said first major surface, said sealant layer having a surface
available for contacting a substrate, said sealant layer comprising
a sealant composition comprising a blend of an epoxy resin, a
semi-crystalline polyester, and a curing agent selected from the
group consisting of (a) thermally activated agents characterized by
a thermal activation temperature and (b) photo-active curing agents
characterized by a thermal decomposition temperature, said sealant
composition characterized in that prior to cure, said composition
substantially retains its shape when heated to a temperature
greater than the melting temperature of said polyester but less
than (a) the thermal activation temperature of said curing agent,
where said curing agent is a thermally activated agent or (b) the
thermal decomposition temperature of said curing agent, where said
curing agent is a photo-active curing agent, until acted upon by an
external force other than gravity.
35. An article comprising: (a) a substrate having a first major
surface and a second major surface separated by an edge region
having a finite thickness; (b) a conformable, compressible, melt
flow-resistant core layer having first and second major surfaces,
said core layer being affixed at its second major surface to (i)
said first major surface of said substrate and/or (ii) said edge
region of said substrate, said core layer imparting vibration
damping properties to the article; and (c) a thermosettable sealant
layer provided on said first major surface of said core layer, said
sealant layer having a surface available for contacting a second
substrate.
36. An article according to claim 35 wherein said substrate
comprises glass.
37. An article according to claim 35 wherein said substrate
comprises a glass windshield adapted for use in a motor
vehicle.
38. An article according to claim 35 wherein said first major
surface of said substrate is characterized by a first perimeter and
said second major surface of said substrate is characterized by a
second perimeter, said core layer being affixed at its second major
surface to (i) said first major surface of said substrate such that
said core layer extends substantially around the entire perimeter
of said first major surface of said substrate, and/or (ii) said
edge region of said substrate such that said core layer
substantially surrounds said edge region.
39. An article according to claim 35 wherein said thermosettable
sealant layer comprises a photo-active curing agent.
40. An article according to claim 35 wherein said thermosettable
sealant layer comprises a blend of (a) an epoxy resin, (b) a resin
selected from the group consisting of polyacrylates,
semi-crystalline polyesters, and combinations thereof, and (c) a
curing agent selected from the group consisting of (i) thermally
activated agents characterized by a thermal activation temperature
and (ii) photo-active curing agents characterized by a thermal
decomposition temperature.
41. An article according to claim 35 wherein said thermosettable
sealant layer substantially retains it shape when heated to a
temperature greater than the softening temperature of said
composition, but less than about 200.degree. C., until acted upon
by an external force other than gravity.
42. An article according to claim 35 wherein said thermosettable
sealant layer comprises a curing agent selected from the group
consisting of (a) thermally activated agents characterized by a
thermal activation temperature and (b) photo-active curing agents
characterized by a thermal decomposition temperature, said sealant
composition characterized in that prior to cure, said composition
substantially retains its shape when heated to a temperature
greater than the softening temperature of said composition, but
less than (a) the thermal activation temperature of said curing
agent, where said curing agent is a thermally activated curing
agent, or (b) the thermal decomposition temperature of said curing
agent, where said curing agent is a photo-active curing agent,
until acted upon by an external force other than gravity.
43. An article according to claim 35 wherein said sealant layer
comprises a sealant composition comprising a blend of an epoxy
resin, a semi-crystalline polyester, and a curing agent selected
from the group consisting of (a) thermally activated agents
characterized by a thermal activation temperature and (b)
photo-active curing agents characterized by a thermal decomposition
temperature, said sealant composition characterized in that prior
to cure, said composition substantially retains its shape when
heated to a temperature greater than the melting temperature of
said polyester but less than (a) the thermal activation temperature
of said curing agent, where said curing agent is a thermally
activated curing agent or (b) the thermal decomposition temperature
of said curing agent, where said curing agent is a photo-active
curing agent, until acted upon by an external force other than
gravity.
44. An article according to claim 35 wherein said core layer has an
ultimate tensile strength no greater than the ultimate tensile
strength of said sealant layer.
45. An article according to claim 35 wherein said core layer
comprises a foam.
46. An article according to claim 35 further comprising a bonding
layer interposed between said second major surface of said core
layer and (a) said first major surface of said substrate where said
core layer is affixed to said first major surface of said
substrate, and/or (b) said edge region where said core layer is
affixed to said edge region.
47. A windshield adapted for use in a motor vehicle comprising: (a)
a glass substrate having a first major surface characterized by a
first perimeter and a second major surface characterized by a
second perimeter, said first and second surfaces being separated by
an edge region having a finite thickness; (b) a conformable,
compressible, melt flow-resistant core layer having first and
second major surfaces, said core layer being affixed at its second
major surface to said first major surface of said glass substrate
such that said core layer extends substantially around the entire
perimeter of said first major surface of said glass substrate said
core layer having vibration damping properties; and (c) a sealant
layer provided on said first major surface of said core layer, said
sealant layer having a surface available for contacting a
substrate.
48. An article according to claim 47 wherein said sealant layer
comprises a thermosetting sealant composition comprising a curing
agent selected from the group consisting of (a) thermally activated
agents curing characterized by a thermal activation temperature and
(b) photo-active curing agents characterized by a thermal
decomposition temperature, said sealant composition characterized
in that prior to cure, said composition substantially retains its
shape when heated to a temperature greater than the softening
temperature of said composition, but less than (a) the thermal
activation temperature of said curing agent, where said curing
agent is a thermally activated curing agent, or (b) the thermal
decomposition temperature of said curing agent, where said curing
agent is a photo-active curing agent, until acted upon by an
external force other than gravity.
49. An article according to claim 47 wherein said sealant layer
comprises a sealant composition comprising a blend of an epoxy
resin, a semi-crystalline polyester, and a curing agent selected
from the group consisting of (a) thermally activated curing agents
characterized by a thermal activation temperature and (b)
photo-active curing agents characterized by a thermal decomposition
temperature, said sealant composition characterized in that prior
to cure, said composition substantially retains its shape when
heated to a temperature greater than the melting temperature of
said polyester but less than (a) the thermal activation temperature
of said curing agent, where said curing agent is a thermally
activated curing agent or (b) the thermal decomposition temperature
of said curing agent, where said curing agent is a photo-active
curing agent, until acted upon by an external force other than
gravity.
50. An article according to claim 47 wherein said core layer has an
ultimate tensile strength no greater than the ultimate tensile
strength of said sealant layer.
51. An article according to claim 47 wherein said core layer
comprises a foam.
52. An article comprising (a) a substrate having a first major
surface characterized by a first perimeter and a second major
surface characterized by a second perimeter, said first and second
surfaces being separated by an edge region having a finite
thickness; (b) a conformable, compressible, melt flow-resistant
core layer having first and second major surfaces, said core layer
being affixed at its second major surface to (i) said first major
surface of said substrate such that said core layer extends
substantially around the entire perimeter of said first major
surface of said substrate, and/or (ii) said edge region of said
substrate such that said core layer substantially surrounds said
edge region, said core layer imparting vibration damping properties
to the article; (c) a sealant layer provided on said first major
surface of said core layer; and (d) a second substrate joined to
said first substrate through said sealant layer.
53. An article according to claim 52 wherein said first substrate
comprises glass and said second substrate comprises metal.
54. An article according to claim 52 wherein said first substrate
comprises glass and said second substrate comprises a painted
substrate.
55. An article according to claim 52 wherein said first substrate
comprises a windshield and said second substrate comprises a frame
for supporting said windshield.
56. An article according to claim 52 wherein said sealant layer
comprises a thermosetting composition comprising a photo-active
curing agent.
57. An article according to claim 52 wherein said sealant layer
comprises a thermosetting blend comprising (a) an epoxy resin, (b)
a resin selected from the group consisting of polyacrylates,
semi-crystalline polyesters, and combinations thereof, and (c) a
curing agent selected from the group consisting of (i) thermally
activated curing agents characterized by a thermal activation
temperature and (ii) photo-active curing agents characterized by a
thermal decomposition temperature.
58. An article according to claim 52 wherein said sealant layer
comprises a thermoplastic or thermosetting sealant composition
that, prior to cure in the case of thermosetting sealant
compositions, substantially retains it shape when heated to a
temperature greater than the softening temperature of said
composition, but less than about 200.degree. C., until acted upon
by an external force other than gravity.
59. An article according to claim 52 wherein said sealant layer
comprises a thermosetting sealant composition comprising a curing
agent selected from the group consisting of (a) thermally activated
curing agents characterized by a thermal activation temperature and
(b) photo-active curing agents characterized by a thermal
decomposition temperature, said sealant composition characterized
in that prior to cure, said composition substantially retains its
shape when heated to a temperature greater than the softening
temperature of said composition, but less than (a) the thermal
activation temperature of said curing agent, where said curing
agent is a thermally activated curing agent, or (b) the thermal
decomposition temperature of said curing agent, where said curing
agent is a photo-active curing agent, until acted upon by an
external force other than gravity.
60. An article according to claim 52 wherein said sealant layer
comprises a sealant composition comprising a blend of an epoxy
resin, a semi-crystalline polyester, and a curing agent selected
from the group consisting of (a) thermally activated curing agents
characterized by a thermal activation temperature and (b)
photo-active curing agents characterized by a thermal decomposition
temperature, said sealant composition characterized in that prior
to cure, said composition substantially retains its shape when
heated to a temperature greater than the melting temperature of
said polyester but less than (a) the thermal activation temperature
of said curing agent, where said curing agent is a thermally
activated curing agent or (b) the thermal decomposition temperature
of said curing agent, where said curing agent is a photo-active
curing agent, until acted upon by an external force other than
gravity.
61. An article according to claim 52 wherein said core layer has an
ultimate tensile strength no greater than the ultimate tensile
strength of said sealant layer.
62. An article according to claim 52 wherein said core layer
comprises a foam.
63. An article according to claim 52 further comprising a bonding
layer interposed between said second major surface of said core
layer and (a) said first major surface of said first substrate
where said core layer is affixed to said first major surface of
said first substrate and/or (b) said edge region where said core
layer is affixed to said edge region.
64. A method of joining a first substrate to a second substrate
comprising: (a) providing an article comprising: (1) a first
substrate having a first major surface and a second major surface
separated by an edge region having a finite thickness; (2) a
conformable, compressible, melt flow-resistant core layer having
first and second major surfaces, said core layer being affixed at
its second major surface to (i) said first major surface of said
first substrate and/or (ii) said edge region of said first
substrate, said core layer having vibration damping properties; and
(3) a thermosettable sealant layer provided on said first major
surface of said core layer, said sealant layer having a surface
available for contacting a second substrate; and (b) contacting
said sealant layer with a second substrate to join said second
substrate to said first substrate through said sealant layer.
65. A method according to claim 64 wherein said first major surface
of said first substrate is characterized by a first perimeter and
said second major surface of said first substrate is characterized
by a second perimeter, said core layer being affixed at its second
major surface to (i) said first major surface of said first
substrate such that said core layer extends substantially around
the entire perimeter of said first major surface of said first
substrate, and/or (ii) said edge region of said first substrate
such that said core layer substantially surrounds said edge
region.
66. A method according to claim 64 wherein said first substrate
comprises glass and said second substrate comprises metal.
67. A method according to claim 64 wherein said first substrate
comprises glass and said second substrate comprises a painted
substrate.
68. A method according to claim 64 wherein said first substrate
comprises a windshield and said second substrate comprises a frame
for supporting said windshield.
69. A method according to claim 64 wherein said second substrate
comprises a U-shaped bracket.
70. A method according to claim 64 wherein said thermosettable
sealant layer comprises a photo-active curing agent.
71. A method according to claim 64 wherein said thermosettable
sealant layer comprises a blend of (a) an epoxy resin, (b) a resin
selected from the group consisting of polyacrylates,
semi-crystalline polyesters, and combinations thereof, and (c) a
curing agent selected from the group consisting of (i) thermally
activated agents characterized by a thermal activation temperature
and (ii) photo-active curing agents characterized by a thermal
decomposition temperature.
72. A method according to claim 64 wherein said thermosettable
sealant layer substantially retains it shape when heated to a
temperature greater than the softening temperature of said
composition, but less than about 200.degree. C., until acted upon
by an external force other than gravity.
73. A method according to claim 64 wherein said thermosettable
sealant layer comprises a curing agent selected from the group
consisting of (a) thermally activated curing agents characterized
by a thermal activation temperature and (b) photo-active curing
agents characterized by a thermal decomposition temperature, said
sealant composition characterized in that prior to cure, said
composition substantially retains its shape when heated to a
temperature greater than the softening temperature of said
composition, but less than (a) the thermal activation temperature
of said curing agent, where said curing agent is a thermally
activated curing agent, or (b) the thermal decomposition
temperature of said curing agent, where said curing agent is a
photo-active curing agent, until acted upon by an external force
other than gravity.
74. A method according to claim 64 wherein said thermosettable
sealant layer comprises a blend of an epoxy resin, a
semi-crystalline polyester, and a curing agent selected from the
group consisting of (a) thermally activated curing agents
characterized by a thermal activation temperature and (b)
photo-active curing agents characterized by a thermal decomposition
temperature, said sealant composition characterized in that prior
to cure, said composition substantially retains its shape when
heated to a temperature greater than the melting temperature of
said polyester but less than (a) the thermal activation temperature
of said curing agent, where said curing agent is a thermally
activated curing agent or (b) the thermal decomposition temperature
of said curing agent, where said curing agent is a photo-active
curing agent, until acted upon by an external force other than
gravity.
75. A method according to claim 64 wherein said core layer has an
ultimate tensile strength no greater than the ultimate tensile
strength of said sealant layer.
76. A method according to claim 64 wherein said core layer
comprises a foam.
77. A method according to claim 64 further comprising a bonding
layer interposed between said second major surface of said core
layer and (a) said first major surface of said first substrate
where said core layer is affixed to said first major surface of
said first substrate and/or (b) said edge region where said core
layer is affixed to said edge region.
78. A method according to claim 70 comprising (a) heating said
sealant layer under conditions that cause said sealant layer to
soften and (b) photo-activating said sealant layer to initiate cure
of said sealant layer.
79. A method of joining a windshield to a motor vehicle comprising:
(a) providing a windshield comprising (1) a glass substrate having
a first major surface characterized by a first perimeter and a
second major surface characterized by a second perimeter, said
first and second surfaces being separated by an edge region having
a finite thickness; (2) a conformable, compressible, melt
flow-resistant core layer having first and second major surfaces,
said core layer being affixed at its second major surface to said
first major surface of said glass substrate such that said core
layer extends substantially around the entire perimeter of said
first major surface of said glass substrate said core layer having
vibration damping properties; and (3) a sealant layer provided on
said first major surface of said core layer; and (b) joining said
windshield to said frame through said sealant layer.
80. A sealant composition comprising a blend of an epoxy resin, a
semi-crystalline polyester, and a curing agent selected from the
group consisting of (a) thermally activated curing agents
characterized by a thermal activation temperature and (b)
photo-active curing agents characterized by a thermal decomposition
temperature, said sealant composition characterized in that prior
to cure, said composition substantially retains its shape when
heated to a temperature greater than the melting temperature of
said polyester but less than (a) the thermal activation temperature
of said curing agent, where said curing agent is a thermally
activated curing agent or (b) the thermal decomposition temperature
of said curing agent, where said curing agent is a photo-active
curing agent, until acted upon by an external force other than
gravity.
81. A sealant composition according to claim 80 wherein said
sealant composition further comprises a thixotropic agent.
82. A sealant composition according to claim 81 wherein said
thixotropic agent is selected from the group consisting of
particles, chopped fibers, bubbles, beads and combinations
thereof.
83. A sealant composition according to claim 82 wherein said
thixotropic agent comprises silica particles.
84. A sealant composition according to claim 80 wherein said curing
agent comprises a photo-active curing agent.
85. A sealant composition according to claim 80 wherein said curing
agent comprises a thermally activated curing agent.
86. A sealant composition according to claim 80 wherein prior to
cure, said composition substantially retains its shape when heated
to a temperature greater than the melting temperature of said
polyester, but less than about 200.degree. C., until acted upon by
an external force other than gravity.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to establishing a seal between two
substrates, particularly where at least one of the substrates is
glass.
[0002] Many applications exist where it is necessary to secure a
glass substrate within a frame such as a metal, plastic or wood
frame, which may be painted. For example, glass windshields are
secured within the metal or plastic frame of a motor vehicle both
during vehicle manufacture and following manufacture to replace the
windshield in the event that it cracks or breaks.
[0003] It is difficult to establish a strong bond to glass using
conventional sealants and adhesives such as polyurethane pastes. To
enhance adhesion, the glass surface is typically primed prior to
inserting it into the frame.
[0004] Polyurethane pastes are conventionally used to establish a
seal between the primed glass and the frame. Such pastes, however,
are difficult to apply uniformly and reproducibly. Another problem
is that pushing the glass into the frame causes the paste to flow
and squeeze out of the bond line. This creates bond lines of uneven
thickness and glass-frame contact points that can act as failure
points because any stress applied to the frame is transmitted
directly to the glass at these points. This is particularly a
problem when a motor vehicle windshield is installed into a frame
that has a highly uneven surface. To address this problem,
discontinuous "spacers" are typically placed at various points
around the perimeter of the frame. While these spacers help avoid
creating glass-frame contact points, they also act as stress
concentration points because while the sealant shrinks during cure,
the spacers do not. It is then necessary to use extra sealant to
accommodate the spacers.
[0005] Another problem is encountered in the case of polyurethane
sealant pastes that require a relatively long time to cure and
build bond strength such as those which are moisture-curable.
During this vulnerable curing period, the glass can vibrate within
the frame, making the seal and the glass susceptible to damage.
Gaps in the seal can form, giving rise to wind noise and
compromising seal integrity. The noise associated with the
vibrations is also undesirable. Moreover, the reliance on ambient
moisture means that the cure process varies depending upon ambient
conditions.
SUMMARY OF THE INVENTION
[0006] In a first aspect, the invention features an article (e.g.,
in the form of a tape) that includes (a) a conformable,
compressible, melt flow-resistant foam core layer having first and
second major surfaces, and (b) a the thermosettable sealant layer
on said first major surface of the core layer. The sealant layer
has a surface available for contacting a substrate.
[0007] A "sealant composition" or a "sealant layer" is a
gap-filling material. Consequently, at the time of seal formation,
sealant compositions according to the invention have an elasticity
that is sufficiently low such that the sealant composition is able
to flow into and fill gaps in the substrate to which it is applied
and, after the sealant has cured (in the case of thermosetting
sealant compositions) or solidified upon cooling (in the case of
thermoplastic sealant compositions), still sufficiently fill the
gaps so as to seal the substrate. Both the surface of the sealant
layer available for contacting a substrate and the bulk composition
of the sealant layer meet these criteria. Sealant compositions
useful in the invention are non-tacky (i.e., they are not tacky to
the touch) once they have cured (in the case of thermosetting
sealant compositions) or solidified upon cooling (in the case of
thermoplastic sealant compositions).
[0008] In addition, the sealant compositions do not meet the
definition of a pressure sensitive adhesive as established by the
Pressure Sensitive Tape Council (PSTC), Glenview, Ill. According to
the PSTC Glossary of Terms (August, 1985 revision), pressure
sensitive adhesives are aggressively and permanently tacky at room
temperature and firmly adhere to a wide variety of dissimilar
surfaces upon mere contact and without the need for more than
finger or hand pressure. They require no activation by water,
solvent or heat in order to exert a strong adhesive holding force
toward materials such as paper, plastic, glass, wood, cement and
metals. They have a sufficiently cohesive holding and elastic
nature so that, despite their aggressive tackiness, they can be
handled with the fingers and removed from smooth surfaces without
leaving a residue.
[0009] A "thermosetting" or "thermosettable" composition is one
which can be cured (i.e., crosslinked), for example by exposure to,
preferably, heat or actinic radiation (although exposure to
moisture or other chemical means may also suffice), to yield a
substantially infusible (i.e., thermoset) material. Combinations of
these various curing means may also be used (e.g., a combination of
heat and actinic radiation). Such compositions may include a curing
agent (e.g., a thermal or photo-active curing agent).
[0010] A "thermoplastic" composition is one which is capable of
being repeatedly softened by heat and hardened by cooling.
[0011] A "melt flow-resistant" material is a material that resists
undergoing macroscopic mass flow under conditions at which the
sealant layer exhibits macroscopic flow. Typically, the melt
flow-resistant material resists undergoing macroscopic mass flow
when subject to temperatures of up to about 200.degree. C.
[0012] A "conformable, compressible" material is a material that
readily deforms when subjected to an applied stress, but will tend
to elastically recover when the stress is removed within the time
frame that it takes to establish a seal between two substrates of
interest, although some permanent set or deformation may occur
depending on the stress to which the material is subjected in a
given application.
[0013] In one embodiment, the thermosettable sealant layer includes
a blend of (a) an epoxy resin, (b) a resin selected from the group
consisting of polyacrylates, semi-crystalline polyesters, and
combinations thereof, and (c) a curing agent selected from the
group consisting of (i) thermally activated curing agents
characterized by a thermal activation temperature and (ii)
photo-active curing agents characterized by a thermal decomposition
temperature.
[0014] In another embodiment, the thermosettable sealant layer
substantially retains its shape when heated to a temperature
greater than the softening temperature of the composition, but less
than about 200.degree. C., until acted upon by an external force
other than gravity. Such force includes the pressure exerted during
sealing by pushing two substrates together. One test for
determining whether a given composition exhibits this behavior
involves placing a sample of the composition on a plate maintained
at an angle in an oven, heating the sample to the desired
temperature, and observing the extent to which the sample loses its
initial shape and flows down the surface of the plate within a set
period of time. Because the test is conducted in the absence of an
applied external force, any such flow is attributable to the
combined effect of temperature and gravity alone. This test is
described in greater detail in the "Examples" section below.
[0015] In another embodiment, the sealant layer includes a
thermosetting sealant composition that includes a curing agent
selected from the group consisting of (a) thermally activated
curing agents characterized by a thermal activation temperature,
and (b) photo-active curing agents characterized by a thermal
decomposition temperature. The sealant composition is characterized
in that, prior to cure, the composition substantially retains its
shape when heated to a temperature greater than the softening
temperature of the composition, but less than (a) the thermal
activation temperature of the curing agent, where the curing agent
is a thermally activated curing agent, or (b) the thermal
decomposition temperature of the curing agent, where the curing
agent is a photo-active curing agent, until acted upon by an
external force other than gravity, measured according to the test
procedure generally described above.
[0016] An example of a preferred sealant composition includes a
blend of an epoxy resin, a semi-crystalline polyester, and a curing
agent selected from the group consisting of (a) thermally activated
curing agents characterized by a thermal activation temperature,
and (b) photo-active curing agents characterized by a thermal
decomposition temperature. The sealant composition is characterized
in that, prior to cure, the sealant composition substantially
retains its shape when heated to a temperature greater than the
melting temperature of the polyester but less than (a) the thermal
activation temperature of the curing agent, where the curing agent
is a thermally activated curing agent or (b) the thermal
decomposition temperature of the curing agent, where the curing
agent is a photo-active curing agent, until acted upon by an
external force other than gravity, measured according to the test
procedure generally described above. Preferably, this sealant
composition substantially retains its shape when heated to a
temperature greater than the melting temperature of the polyester,
but less than about 200.degree. C., until acted upon by an external
force other than gravity.
[0017] The core layer preferably has a tensile strength no greater
than the tensile strength of the sealant layer. Examples of
suitable core layers include foams, which may be open or closed
cell foams, although closed cell foams are preferred. Examples of
suitable foams include polyacrylic, polyurethane and polyolefin
foams. Also useful are core layers in the form of pressure
sensitive adhesives, e.g., pressure sensitive adhesive foams.
[0018] The article may further include a bonding layer provided on
the second major surface of the core layer. In such embodiments,
the sealant layer and the bonding layer preferably are thermally
insulated from each other.
[0019] In a second aspect, the invention features an article that
includes (a) a conformable, compressible, melt flow-resistant
thermoset core layer having first and second major surfaces, and
(b) a thermosettable sealant layer on said first major surface of
the core layer. The sealant layer has a surface available for
contacting a substrate. The thermoset core layer may be provided
by, for example, a closed cell foam or a pressure sensitive
adhesive. Useful thermosettable sealant layers include those which
were described above.
[0020] In a third aspect, the invention features an article that
includes (a) a conformable, compressible, melt flow-resistant core
layer having first and second major surfaces, and (b) a
thermoplastic sealant layer on said first major surface of the core
layer. The sealant layer has a surface available for contacting a
substrate and is formed from a thermoplastic polymer selected from
the group consisting of polyurethanes, polyesters,
polyaromatic-containing block copolymers, and silicones. Useful
core layers include those previously described.
[0021] In a fourth aspect, the invention features an article
comprising (a) a conformable, compressible, melt flow-resistant
thermoset core layer having first and second major surfaces, (b) a
sealant layer on said first major surface of said core layer and
having a surface available for contacting a substrate, and (c) a
thermosettable bonding layer on said second major surface of said
core layer and having a surface available for contacting a second
substrate. Useful core and sealant layers include those materials
previously mentioned.
[0022] In a fifth aspect, the invention features an article that
includes (a) a substrate having a first major surface and a second
major surface separated by an edge region having a finite
thickness; (b) a conformable, compressible, melt flow-resistant
core layer having first and second major surfaces; and (c) a
thermosettable sealant layer provided on the first major surface of
the core layer and having a surface available for contacting a
second substrate. Examples of suitable core and sealant layers
include the materials described above. The core layer is affixed at
its second major surface to (i) the first major surface of the
substrate and/or (ii) the edge region of the substrate. The core
layer imparts vibration damping properties to the article.
[0023] The invention also features a method for joining these
articles to a second substrate by contacting the sealant layer with
the second substrate to join the second substrate to the first
substrate through the sealant layer.
[0024] An example of a preferred substrate is glass, e.g., a glass
windshield adapted for use in a motor vehicle. Such substrates can
be joined to, e.g., metal substrates, painted substrates (e.g.,
painted metal substrates), and, in the case of windshields, frames
of the type found in motor vehicles. Higher surface energy
substrates are particularly usefully joined to each other. Another
example of a second substrate is a U-shaped bracket into which the
sealant-bearing article can be placed.
[0025] In one embodiment, particularly useful in the case of
windshields or substrates installed in grooves, the first major
surface of the substrate is characterized by a first perimeter, the
second major surface of said substrate is characterized by a second
perimeter, and the core layer is affixed at its second major
surface to (i) the first major surface of the substrate such that
the core layer extends substantially around the entire perimeter of
the first major surface of the first substrate, and/or (ii) the
edge region of the substrate such that the core layer substantially
surrounds the edge region.
[0026] In a sixth aspect, the invention features an article that
includes (a) a substrate having a first major surface characterized
by a first perimeter and a second major surface characterized by a
second perimeter, in which the first and second surfaces are
separated by an edge region having a finite thickness; (b) a
conformable, compressible, melt flow-resistant core layer having
first and second major surfaces; (c) a sealant layer provided on
the first major surface of the core layer; and (d) a second
substrate joined to the first substrate through the sealant layer.
The core layer is affixed at its second major surface to (i) the
first major surface of the first substrate such that the core layer
extends substantially around the entire perimeter of the first
major surface of the first substrate, and/or (ii) the edge region
of the substrate such that the core layer substantially surrounds
the edge region. The core layer imparts vibration damping
properties to the article. Examples of suitable core and sealant
layers include the materials described above.
[0027] In one preferred embodiment, the first substrate includes
glass and the second substrate includes metal. In a second
preferred embodiment, the first substrate includes glass and the
second substrate includes a painted substrate (e.g., a painted
metal substrate). In one particularly preferred embodiment, the
first substrate is a glass windshield and the second substrate is a
frame (e.g., formed in a motor vehicle) for supporting the
windshield.
[0028] In a seventh aspect, the invention features a sealant
composition that includes a blend of an epoxy resin, a
semi-crystalline polyester, and a curing agent selected from the
group consisting of (a) thermally activated curing agents
characterized by a thermal activation temperature, and (b)
photo-active curing agents characterized by a thermal decomposition
temperature. The sealant composition is characterized in that,
prior to cure, the composition substantially retains its shape when
heated to a temperature greater than the melting temperature of the
polyester but less than (a) the thermal activation temperature of
the curing agent, where the curing agent is a thermally activated
curing agent, or (b) the thermal decomposition temperature of the
curing agent, where the curing agent is a photo-active curing
agent, until acted upon by an external force other than gravity,
measured according to the test procedure described generally
above.
[0029] In preferred embodiments, the sealant composition further
includes a thixotropic agent, e.g., selected from the group
consisting of particles (such as silica particles), chopped fibers,
bubbles (such as glass, ceramic or polymeric bubbles), and
combinations thereof Prior to cure, the composition preferably
substantially retains its shape when heated to a temperature
greater than the melting temperature of the polyester, but less
than about 200.degree. C., until acted upon by an external force
other than gravity.
[0030] The invention provides an easy-to-use sealant in the form of
an article such as a tape for establishing a seal between two
substrates that is particularly useful where at least one of the
substrates is glass. The sealant and one of the substrates may be
provided in the form of a single, ready-to-use article. The sealant
can be applied uniformly and consistently, and does not excessively
squeeze out when the substrate is pushed into a frame. Thus,
clean-up following the sealing operation is simplified. The
sealants may also be used without a primer.
[0031] Once placed between two substrates the preferred sealants
build strength quickly, resulting in a seal having good green
strength. Thus, it minimizes or eliminates the need for special
precautions to support one, or both, of the substrates during the
sealing operation. The rapid build-up of strength also eliminates
problems relating to stresses imposed on the substrate prior to
full cure such as may be caused by movement of the substrate
relative to the frame. Thus, for example, in the case of windshield
installation, it is possible to drive away in the vehicle bearing
the newly installed windshield before cure is complete.
[0032] The ability to build green strength rapidly, coupled with
the ability to eliminate processing steps such as priming and
cleaning up excess sealant squeezed out of the bond line,
simplifies the sealing process. This, in turn, facilitates use of
the sealants in a motor vehicle assembly line. In addition, this
imparts greater flexibility to the motor vehicle assembly process.
For example, instead of installing the windshield early in the
manufacturing process to allow time for sealant cure before the
vehicle is driven off the manufacturing line, it becomes possible
to install the windshield late in the manufacturing process.
[0033] The preferred sealants can be stored for extended periods of
time without degrading because cure does not commence until the
composition is exposed to heat or actinic radiation.
Advantageously, the preferred heat- or actinic radiation-curable
sealants cure relatively independently of ambient conditions that
could limit the utility of temperature- and humidity-sensitive
materials such as moisture-curable sealants.
[0034] Following cure, the sealant forms a tough, ductile material
having good tensile strength. Thus, it maintains a good seal
between the substrate and the frame even when the seal is subjected
to ambient moisture and stress, e.g., of the type encountered
during motor vehicle use. In addition, the sealant exhibits low
shrinkage upon cure, thereby maintaining the seal and minimizing
stress to the substrate. Particularly in the case of glass
substrates, such stresses can cause the glass to crack.
[0035] The compressible, conformable core layer acts as an integral
bond line spacer and forms a vibration damping cushion on which the
substrate floats within the frame. Because it preferably is
substantially continuous around the perimeter of the substrate
surface, it can advantageously accommodate and dissipate stresses
to which the article is subjected under normal use conditions. An
additional advantage is that the preferred constructions, under
high shear rate catastrophic impact, may transmit the imposed
stress to the substrates. In addition, the compressible,
conformable property of the core layer allows for greater sealing
capacity, thus reducing the amount of sealant needed and minimizing
squeeze out.
[0036] Other features and advantages will be apparent from the
following description of the preferred embodiments thereof, and
from the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] The invention will be more fully understood with reference
to the following drawings in which similar reference numerals
designate like or analogous components throughout and in which:
[0038] FIG. 1 is an enlarged, fragmentary, cross-sectional view of
a multi-layer article according to the invention;
[0039] FIG. 2 is a plan view of a motor vehicle windshield having a
multi-layer tape secured to one major face thereof according to the
invention;
[0040] FIG. 3 is an enlarged cross-sectional view taken along lines
3--3 in FIG. 2;
[0041] FIG. 4 is an exploded perspective view illustrating the
installation of a windshield into a motor vehicle according to the
invention;
[0042] FIG. 5 is a schematic cross-sectional drawing showing,
according to the invention, the use of a multi-layer tape to secure
a windshield to a frame in a motor vehicle;
[0043] FIG. 6 is a plan view of a substrate having a multi-layer
tape secured to an edge surface thereof according to the
invention;
[0044] FIG. 7 is an enlarged cross-sectional view taken along lines
7--7 in FIG. 6; and
[0045] FIG. 8 is a sectional view illustrating a substrate sealed
into a bracket using a multi-layer tape according to the
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMOBDIMENTS
[0046] Article
[0047] FIG. 1 illustrates a multi-layer article 10 in the form of a
tape useful for establishing a seal between two substrates. Tape 10
features a sealant layer 12, a core layer 14, an optional bonding
layer 16, and an optional, temporary, removable liner 18 for
protecting the bonding layer (if present) or the core layer. Liner
18 is removed prior to attaching the surface that it protects to a
substrate. Alternatively, optional bonding layer 16 may be replaced
by an optional, second sealant layer.
[0048] Conveniently, though not shown separately in the drawings,
tape 10 may be provided in the form a roll of tape for easy
storage, shipping, handling and use. In such constructions, tape 10
is typically wound about a paper or plastic core having a diameter,
conventionally, of about 7.6 centimeters. In such constructions,
the tape may be wound up with a temporary, removable liner that
separates adjacent windings in the roll. The provision of tape 10
in roll form is facilitated by selecting the sealant layer to have
a thickness and a modulus that promotes easy wind-up without
exerting a force that could result in permanent deformation of core
layer 14 in the article, oozing of any of the layers in the article
beyond the widest layer in the article, or telescoping of the
article, when stored under ordinary, ambient conditions of
temperature and humidity.
[0049] Tape 10 can be used to seal a variety of substrates
together. The substrates may be the same as, or different from,
each other. Examples of suitable substrates include glass, metal,
plastic, wood, and ceramic substrates. Representative plastic
substrates include polyvinyl chloride, ethylene-propylene-diene
monomer rubber, polyurethanes, polymethyl methacrylate, engineering
thermoplastics (e.g., polyphenylene oxide, polyetheretherketone,
polycarbonate), and thermoplastic elastomers, including
thermoplastic elastomeric olefins. Glass, and polymers which may be
used as substitutes for glass (e.g., polycarbonate and polymethyl
methacrylate), may be referred to as glazing materials. Tape 10 is
particularly effective in sealing substrates that have a higher
surface energy (as measured by a Zisman critical wetting tension
greater than 35 millijoules/m.sup.2) such as metal, painted metal
and many polymers. The surface of the substrate may be coated,
e.g., with paint, an abrasion-resistant coating, or an anti-glare
coating. In the case of, e.g., windshields, the glass may include a
ceramic-frit layer.
[0050] Tape 10 is particularly useful for sealing glass substrates
to, e.g., metal and plastic substrates. For example, article 10 is
particularly useful for sealing a glass windshield to a metal or
plastic frame in a motor vehicle.
[0051] Core layer 14 supports sealant layer 12. One purpose of core
layer 14 is to act as an integral spacer when tape 10 is used to
establish a seal between a pair of substrates. Thus, during
pressurized application of the tape-bearing substrate to the other
substrate, core layer 14 prevents the two substrates from coming
together in the event that the sealant is displaced. Such contact
is particularly undesirable where one of the substrates is glass
because the resulting stress can cause the glass to break. Core
layer 14 also dissipates stress resulting from cure of the sealant,
thereby minimizing stress in the seal.
[0052] Core layer 14 also preferably acts as an internal vibration
damper to minimize noise associated with variable frequency
substrate movement once the two substrates have been sealed
together. The core layer also isolates the substrate to which it is
affixed from stresses transmitted to that substrate and from the
other substrate. For example, in the case of a glass windshield
installed in a motor vehicle, the core layer damps vibrations
arising from wind impinging on the glass, as well as vibrations
arising from the motor vehicle frame.
[0053] Another function of core layer 14 is to thermally insulate
sealant layer 12 from bonding layer 16, regardless of whether the
bonding layer is integral with tape 10, or applied separately to
the substrate surface prior to application of the tape. In this
way, the respective curing reactions that may take place in the
sealant and bonding layers can be isolated from each other,
affording the opportunity to cure the tape in stages. It also
offers the advantage of increasing formulation freedom with respect
to the compositions of the sealant and bonding layers.
[0054] Yet another function of core layer 14 is to act as a failure
zone such that cohesive failure of the tape (as opposed to failure
at a tape/substrate interface) preferentially occurs in the core
layer, rather than the sealant layer or the bonding layer (if
present). This feature is particularly advantageous when bonding
glass substrates such as windshields to a metal or plastic frame in
a motor vehicle because it ensures that adhesive bonds between the
glass and the tape, and between the tape and vehicle, remain intact
when subject to stress, thereby enhancing overall performance.
[0055] To achieve these functions core layer 14 is designed to be
compressible and conformable. These features enable core layer 14,
for example, to cushion the substrate to which the tape is affixed,
and to absorb and distribute stress applied to the sealed
construction. In addition, compressibility and conformability aid
in achieving complete body contact and seal formation.
[0056] Core layer 14 is also designed to be melt-flow resistant
such that it does not undergo macroscopic mass flow when exposed to
the temperatures and pressures used during the sealing
operation.
[0057] To promote cohesive failure of tape 10, core layer 14 is
preferably formulated to be weaker than either the sealant layer or
the bonding layer (if present). That is, the ultimate tensile
strength of the core layer is no greater than the ultimate tensile
strength of either the sealant layer or the bonding layer (if
present) so as to encourage cohesive failure within the core layer.
For example, the ultimate tensile strength of the core layer is
preferably no greater than about 80% of the ultimate tensile
strength of either the sealant layer or the bonding layer, as
measured according to the test procedure described in the
"Examples" section below. "Ultimate tensile strength" refers to the
tensile strength as measured under the temperature and humidity
conditions specified in the "Examples" section below and after any
individual thermosettable layers within the tape have cured.
[0058] Typically, core layer 14 has an ultimate tensile strength no
greater than about 6.9 MPa, preferably no greater than about 5.2
MPa, and more preferably no greater than about 3.5 MPa, measured
according to the test procedure described in the "Examples" section
below. The particular maximum tensile strength value is a function
of the application for which tape 10 is designed to be used. For
example, in the case of windshields installed in motor vehicles,
the ultimate tensile strength of the core layer preferably is no
greater than about 3.5 MPa.
[0059] To further localize cohesive failure in the core layer, a
tie layer (not shown separately in the drawings) may be disposed
between the sealant layer and the core layer to enhance adhesion
between the two layers. A second tie layer (also not shown
separately in the drawings) may be similarly disposed between the
core layer and the bonding layer (if present). Enhancing adhesion
between the individual layers increases the likelihood that the
failure mode will be cohesive failure in the core rather than
failure at a tape/substrate interface.
[0060] Useful materials for the tie layer include, for example,
polymeric films, pressure-sensitive adhesives, pressure-activated
adhesives, heat activated adhesives, and the like, any of which may
be latently curable or not. Often, the choice of tie layer is based
upon the composition of the respective layers. For example, in the
case of core and sealant layers having acid functional groups,
thermoplastic polyamides are useful tie layers. In the case of
epoxy-containing sealant layers and acrylic-based cores,
water-borne dispersions of a blend of an epoxy and a polyamide are
useful. Such dispersions are commercially available from Union Camp
Corp., Wayne, N.J. under the designation Micromid.TM. 142LTL. Other
methods for enhancing adhesion between the individual layers of
tape 10 include providing the core layer with functional groups,
such as carboxylic acid groups, to enable the core layer to bond
covalently to the sealant layer, the bonding layer, or both. The
surface of the core layer may also be treated, e.g., by corona
discharge, to enhance adhesion to adjoining layers.
[0061] The thickness of core layer 14 must be sufficient for the
core layer to perform the bond line spacing function and,
preferably, the vibration damping and thermal insulation functions
as well. The particular thickness of a given core layer is selected
based upon the application for which tape 10 is intended. For
example, in the case of motor vehicle windshield installation, the
thickness of the core layer must be small enough such that the tape
can fit within the frame for which the windshield is designed.
Typically, the thickness of core layer 14 is at least about 1 mm,
preferably at least about 2 mm, and more preferably at least about
3 mm.
[0062] Preferred materials for core layer 14 are viscoelastic
materials. These materials may be thermoplastic or thermoset, with
thermoset materials being preferred. Examples of suitable materials
for core layer 14 include thermoset materials such as polyacrylates
and polyurethanes, and thermoplastic materials such as
ethylene-vinyl acetate copolymers. An example of a suitable,
commercially available material is sold by 3M Company under the
designation Structural Bonding Tape No. 9214.
[0063] Polyurethane-based core layers can be provided as solid
elastomers or as cellular foams and may be formed from one- or
two-part compositions. One-part compositions can be
moisture-activated, in which case water, either purposefully
introduced or acquired from the atmosphere, initiates the curing
reaction. Alternatively, a blocked isocyanate may be used with heat
being employed to unblock the isocyanate and initiate the curing
reaction. Two-part urethanes include a first component that
contains one or more isocyanate-based resins and second component
that contains one or more polyols and curatives.
[0064] Also suitable are pressure sensitive adhesives. Such
adhesives allow the free ends of tape 10 to be fused together in
the form of a joint to yield a continuous seal, preferably a joint
in which the tape ends remain in the same plane such as a
side-to-side joint, scarf joint, or butt joint. In addition, when
core layer 14 is in the form of a pressure sensitive adhesive, it
is possible to bond the core layer directly to the substrate,
thereby eliminating the need for a separate bonding layer (integral
or otherwise).
[0065] Preferably, core layer 14 is in the form of a foam, with
thermoset acrylic foams being particularly preferred. The foam may
have an open or closed cell structure, although closed cell foams
are preferred. Examples of suitable foams are described, for
example, in Levens, U.S. Pat. No. 4,223,067, and Esmay et al., U.S.
Pat. No. 4,415,615. Polyethylene and ethylene vinyl acetate-based
foams may also be used and are typically produced by extruding a
resin composition from an extruder and foaming the material before
or after crosslinking. Commercial suppliers for these types of foam
include Voltek Div. of Sekisui America Corp., Lawrence, Mass. or
Sentinel Products Corp., Hyannis, Mass.
[0066] Other materials that can be incorporated into core layer 14
include, for example, stabilizers, antioxidants, plasticizers,
tackifiers, flow control agents, adhesion promoters (e.g., silanes
and titanates), colorants, thixotropes, and other fillers.
[0067] Sealant layer 12 is preferably in the form of a continuous
layer. However, discontinuous layers may also be used as long as
the sealant fuses under the application of heat and pressure to
form an effective seal in the final article. To aid in achieving a
good seal to irregular surfaces, the surface of sealant layer 12
available for sealing to the second substrate may be textured. In
addition, both single and multi-layer sealant compositions are
envisioned.
[0068] Sealant compositions useful in the invention are non-tacky
(i.e., they are not tacky to the touch) once they have cured (in
the case of thermosetting sealant compositions) or solidified upon
cooling (in the case of thermoplastic sealant compositions). In
order to facilitate the provision of such compositions and to
facilitate the manufacture and handling of tape 10 when it is in
the form of a tape roll, it is preferred that the sealant
composition have a room temperature (i.e., about 23.degree. C.)
shear modulus of at least about 3.times.10.sup.6 dynes/cm.sup.2,
more preferably about 10.sup.7 to 10.sup.10 dynes/cm.sup.2, when
measured at a frequency of 1 hertz.
[0069] The width of sealant layer 12 is application-dependent. In
general, however, the width of sealant layer 12 is no greater than
the width of core layer 14.
[0070] The purpose of sealant layer 12 is to establish and maintain
a seal between a pair of substrates. The sealant is designed to
have a relatively high ultimate tensile strength following cure (in
the case of thermosettable materials) or upon cooling (in the case
of thermoplastic materials), without being brittle, to promote
localized failure in the core layer. The particular minimum tensile
strength value is application-dependent. In general, however,
tensile strengths are on the order of at least about 3.5 MPa,
preferably at least about 5.2 MPa, and more preferably at least
about 6.9 MPa when measured according to the test procedure
described in the "Examples" section below. For example, in the case
of windshields installed in motor vehicles, the ultimate tensile
strength of the sealant layer preferably is greater than about 3.5
MPa.
[0071] After causing the sealant composition to flow and form a
seal (e.g. by applying beat and/or pressure), the sealant layer 12
is preferably designed to build cohesive strength rapidly,
resulting in a construction having good green strength. One measure
of the rate at which strength builds is the overlap shear adhesion
of the sealant layer relative to the core layer, as measured
according to the test procedure described in the "Examples" section
below. Preferably, the overlap shear adhesion of the sealant layer
is greater than the overlap shear adhesion of the core layer within
about 30 minutes following the initial application of heat and
pressure, more preferably within about 15 minutes, and even more
preferably within about 5 minutes. Of course, the sealant
composition also needs to exhibit adequate adhesion to the
substrate surface that it is intended to seal, recognizing that the
desired adhesion may be application dependent. This may be
reflected by a shear adhesion value of preferably at least about 25
psi, more preferably at least about 50 psi, and most preferably at
least about 100 psi. In certain applications, however, higher
values such as at least about 300 psi, more preferably at least
about 500 psi, or even more preferably at least about 700 psi may
be desirable. Such values refer to the measurement of shear
adhesion at a jaw separation rate of 50.8 mm/minute when an
approximately 1 mm thick sealant layer is placed between an
approximately 0.9 mm thick E-coated steel substrate (i.e., using
ED-5 100 coated panels as obtained from Advanced Coating
Technlogies Inc., Hillsdale, Mich.), and an anodized aluminum
substrate as obtained from Hiawatha Panel & Name Plate Co.,
Inc., Minneapolis, Minn.
[0072] The thickness of sealant layer 12 is a function of the
particular sealing application for which article 10 is intended.
Typically, however, the thickness of sealant layer 12 is at least
about 0.25 mm, preferably at least about 1 mm, and more preferably
at least about 1.5 mm, which thicknesses are also useful in
providing article 10 in the form of a roll of tape. In some
applications, the relative thicknesses of core layer 14 and sealant
layer 12 may influence the performance of the multi-layer article
since the compressive force exerted by the core layer on the
sealant layer can contribute to the formation of a good seal to the
substrate. Consequently, it may be desirable in some instances for
the thickness of sealant layer 12 to be at least 30% of the
thickness of core layer 14, more preferably at least 50% of the
thickness of the core layer.
[0073] Melt-flowable compositions may be used for sealant layer 12.
Suitable compositions include thermosettable materials such as
epoxy resins, or the combination of such materials with
thermoplastic materials to form miscible or physical blends.
Examples of such blends are described, e.g., in Johnson et al.,
"Melt-Flowable Materials and Method of Sealing Surface," filed Apr.
12, 1995 and bearing Ser. No. 08/421,055, which is assigned to the
same assignee as the present application and hereby incorporated by
reference, and (b) Kitano et al., U.S. Pat. No. 5,086,088, also
incorporated by reference.
[0074] One suitable class of materials includes blends of epoxy
resins with semi-crystalline polymers such as polyesters, as
described in the aforementioned Johnson et al. application.
Semi-crystalline polymers are advantageous because they contribute
to rapid build-up of sealant strength, leading to a seal having a
high green strength.
[0075] A polymer that is "semi-crystalline" displays a crystalline
melting point, as determined by differential scanning calorimetry
(DSC), preferably with a maximum melting point of about 200.degree.
C. Crystallinity in a polymer is also observed as a clouding or
opacifying of a sheet that had been heated to an amorphous state as
it cools. When the polymer is heated to a molten state and knife
coated onto a liner to form a sheet, it is amorphous and the sheet
is observed to be clear and fairly transparent to light. As the
polymer in the sheet material cools, crystalline domains form and
the crystallization is characterized by the clouding of the sheet
to a translucent or opaque state. The degree of crystallinity may
be varied in the polymers by mixing-in any compatible combination
of amorphous polymers and semi-crystalline polymers having varying
degrees of crystallinity. The clouding of the sheet provides a
convenient non-destructive method of determining that
crystallization has occurred to some degree in the polymer. During
use when the preferred sealants based on blends of epoxy-containing
material and polyester components softens, flows and fills gaps in
the surface to be sealed, the epoxy resin and the polyester
component form a homogenous system as evidenced by a lack of
macroscopic phase separation to the unaided human eye.
[0076] The polymers may include nucleating agents to adjust the
rate of crystallization at a given temperature, and thus the rate
at which green strength builds. Useful nucleating agents include
microcrystalline waxes. A suitable wax is, for example, sold by
Petrolite Corp. as Unilin.TM. 700.
[0077] Preferred polyesters are hydroxyl-terminated and
carboxyl-terminated polyesters that are semi-crystalline at room
temperature. Other functional groups that may be present include
--NH, --CONH, --NH.sub.2, --SH anhydride, urethane, and oxirane
groups.
[0078] The preferred polyesters are also solid at room temperature.
Preferred polyester materials have a number average molecular
weight of about 7,500 to 200,000, more preferably from about 10,000
to 50,000, and most preferably, from about 15,000 to 30,000.
[0079] Polyester components useful in the invention comprise the
reaction product of dicarboxylic acids (or their diester
equivalents, including anhydrides) and diols. The diacids (or
diester equivalents) can be saturated aliphatic diacids containing
from 4 to 12 carbon atoms (including branched, unbranched, or
cyclic materials having 5 to 6 carbon atoms in a ring) and/or
aromatic acids containing from 8 to 15 carbon atoms. Examples of
suitable aliphatic diacids are succinic, glutaric, adipic, pimelic,
suberic, azelaic, sebacic, 1,12-dodecanedioic,
1,4-cyclohexanedicarboxylic, 1,3-cyclopentanedicarboxylic,
2-methylsuccinic, 2-methylpentanedioic, 3-methylhexanedioic acids,
and the like. Suitable aromatic acids include terephthalic acid,
isophthalic acid, phthalic acid, 4,4'-benzophenonedicarboxylic
acid, 4,4'-diphenylmethanedicarboxylic acid,
4,4'-diphenylthioetherdicarboxylic acid, and
4,4'-diphenylaminedicarboxylic acid. Preferably the structure
between the two carboxyl groups in the diacids contain only carbon
and hydrogen, and more preferably, the structure is a phenylene
group. Blends of the foregoing diacids may be used.
[0080] The diols include branched, unbranched, and cyclic aliphatic
diols having from 2 to 12 carbon atoms. Examples of suitable diols
include ethylene glycol, 1,3-propylene glycol, 1,2-propylene
glycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol,
2-methyl-2,4-pentanediol- , 1,6-hexanediol,
cyclobutane-1,3-di(2'-ethanol), cyclohexane-1,4-dimethan- ol,
1,10-decanediol, 1,12-dodecanediol, and neopentyl glycol. Long
chain diols including poly(oxyalkylene)glycols in which the
alkylene group contains from 2 to 9 carbon atoms, preferably 2 to 4
carbon atoms, may also be used. Blends of the foregoing diols may
be used.
[0081] Useful commercially available hydroxyl terminated polyester
materials include various saturated linear, semi-crystalline
copolyesters available from Huls America, Inc. such as Dynapol.TM.
S330, Dynapol.TM. S1401, Dynapol.TM. S1402, Dynapol.TM. S1358,
Dynapol.TM. 1359, Dynapol.TM. S1227, and Dynapol.TM. S1229. Useful
saturated, linear amorphous copolyesters available from Huls
America, Inc. include Dynapol.TM. S1313 and Dynapol.TM. S1430.
[0082] Useful epoxy-containing materials are epoxy resins that have
at least one oxirane ring polymerizable by a ring opening reaction.
Such materials, broadly called epoxides, include both monomeric and
polymeric epoxides and can be aliphatic, cycloaliphatic or
aromatic. These materials generally have, on the average, at least
two epoxy groups per molecule (preferably more than two epoxy
groups per molecule). The "average" number of epoxy groups per
molecule is defined as the number of epoxy groups in the
epoxy-containing material divided by the total number of epoxy
molecules present. The polymeric epoxides include linear polymers
having terminal epoxy groups (e.g., a diglycidyl ether of a
polyoxyalkylene glycol), polymers having skeletal oxirane units
(e.g., polybutadiene polyepoxide), and polymers having pendent
epoxy groups (e.g., a glycidyl methacrylate polymer or copolymer).
The molecular weight of the epoxy-containing material may vary from
58 to about 100,000 or more. Mixtures of various epoxy-containing
materials can also be used.
[0083] Useful epoxy-containing materials include those which
contain cyclohexene oxide groups such as the
epoxycyclohexanecarboxylates, typified by
3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate,
3,4-epoxy-2-methylcyclohexylmethyl-3,4-epoxy-2-methylcyclohexanecarboxyla-
te, and bis(3,4-epoxy-6-methylcyclohexylmethyl) adipate. For a more
detailed list of useful epoxides of this nature, reference may be
made to U.S. Pat. No. 3,117,099.
[0084] Further epoxy-containing materials which are particularly
useful are glycidyl ether monomers such as glycidyl ethers of
polyhydric phenols obtained by reacting a polyhydric phenol with,
e.g., an epichlorohydrin (e.g., the diglycidyl ether of
2,2-bis-(2,3-epoxypropoxyphenol)propane). Further examples of
epoxides of this type which can be used in the practice of this
invention are described in U.S. Pat. No. 3,018,262. Other useful
glycidyl ether based epoxy-containing materials are described in
U.S. Pat. No. 5,407,978.
[0085] There are a number of commercially available
epoxy-containing materials which can be used. In particular,
epoxides which are readily available include octadecylene oxide,
epichlorohydrin, styrene oxide, vinylcyclohexene oxide, glycidol,
glycidyl methacrylate, diglycidyl ether of Bisphenol A (e.g., those
available under the trade designations EPON SU-8, EPON SU-2.5, EPON
828, EPON 1004F, and EPON 1001F from Shell Chemical Co., and
DER-332 and DER-334, from Dow Chemical Co.), diglycidyl ether of
Bisphenol F (e.g., ARALDITE GY281 from Ciba-Geigy),
vinylcyclohexene dioxide (e.g., ERL 4206 from Union Carbide Corp.,
Danbury, Conn.), 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexene
carboxylate (e.g., ERL-4221 from Union Carbide Corp.),
2-(3,4-epoxycylohexyl-5,5-spiro-3,4-epoxy)cyclohexane-metadioxane
(e.g., ERL-4234 from Union Carbide Corp.), bis(3,4-epoxycyclohexyl)
adipate (e.g., ERL-4299 from Union Carbide Corp.), dipentene
dioxide (e.g., ERL-4269 from Union Carbide Corp.), epoxidized
polybutadiene (e.g., OXIRON 2001 from FMC Corp.), epoxy silanes
(e.g., beta-(3,4-epoxycyclohex- yl)ethyltrimethoxysilane and
gamma-glycidoxypropyltrimethoxysilane, commercially available from
Union Carbide), flame retardant epoxy resins (e.g., DER-542, a
brominated bisphenol type epoxy resin available from Dow Chemical
Co.), 1,4-butanediol diglycidyl ether (e.g., ARALDITE RD-2 from
Ciba-Geigy), hydrogenated bisphenol A-epichlorohydrin based epoxy
resins (e.g., EPONEX 1510 from Shell Chemical Co.), and
polyglycidyl ether of phenolformaldehyde novolak (e.g., DEN-431 and
DEN-438 from Dow Chemical Co.).
[0086] Useful photo-active curing agents are cationic and include
aromatic iodonium complex salts, aromatic sulfonium complex salts,
and metallocene salts, and are described in, for example, U.S. Pat.
No. 5,089,536 (Palazzotto). Peroxides and oxalate esters can be
used with the metallocene salts to increase the cure speed, as
described in U.S. Pat. No. 5,252,694 (Willett). Useful commercially
available photo-active curing agents include FX-512, an aromatic
sulfonium complex salt (3M Company), CD-1010 an aromatic sulfonium
complex salt from Sartomer, CD-1012, a diaryliodonium complex salt
from Sartomer, an aromatic sulfonium complex salt (Union Carbide
Corp.), UVI-6974, an aromatic sulfonium complex salt (Union Carbide
Corp.), and IRGACURE 261, a metallocene complex salt (Ciba-Geigy).
Photosensitizers may also be included, for example, to enhance the
efficiency of the photo-active curing agent and/or to adjust the
wavelength of photoactivity. Examples of photosensitizers include
pyrene, fluoroanthrene, benzil, chrysene, p-terphenyl,
acenaphthene, phenanthrene, biphenyl and camphorquinone.
[0087] A variety of thermally activated curing agents may also be
incorporated into the compositions. For example, useful thermally
activated curing agents include amine-, amide-, Lewis acid
complex-, and anhydride-type materials and those which are
preferred include dicyandiamide, imidazoles and polyamine salts.
These are available from a variety of sources, e.g., Omicure.TM.,
available from Omicron Chemical, Ajicure.TM., available from
Ajinomoto Chemical, and Curezol.TM., available from Air
Products.
[0088] In certain cases, it may be advantageous to add an
accelerator to the composition, so that it will fully cure at a
lower temperature, or will fully cure when exposed to heat for
shorter periods. Imidazoles are useful, suitable examples of which
include 2,4-diamino-6-(2'-methylimidaz- oyl)-ethyl-s-triazine
isocyanurate; 2-phenyl-4-benzyl-5-hydroxymethylimida- zole; and
Ni-imidazole-phthalate.
[0089] Other useful blends for sealant layer 14 include
epoxy-acrylate blends, such as those described, e.g., in Kitano et
al., U.S. Pat. No. 5,086,088. These blends are preferably the
photopolymerized reaction product of a composition featuring (i) a
prepolymeric (i.e., partially polymerized to a viscous syrup
typically between about 100 and 10,000 centipoise) or monomeric
syrup of an acrylic or methacrylic acid ester; (ii) optionally, a
reinforcing comonomer; (iii) an epoxy resin; (iv) a photoinitiator;
and (v) a thermally activated curing agent for the epoxy. Also
useful is the thermally polymerized reaction product of a
composition featuring (i) a prepolymeric (i.e., partially
polymerized to a viscous syrup typically between about 100 and
10,000 centipoise) or monomeric syrup of an acrylic or methacrylic
acid ester; (ii) optionally, a reinforcing comonomer; (iii) an
epoxy resin; (iv) a thermal initiator; and (v) a photo-active
curing agent for the epoxy. Suitable epoxy resins, and thermally
activated curing agents include those described above. Examples of
useful photoinitiators include quinones, benzophenones,
triacylimidazoles, acylphosphine oxides, bisimidazoles,
chloroalkyltriazines, benzoin ethers, benzil ketals, thioxanthones,
and acetophenone derivatives, and mixtures thereof Examples of
useful thermal initiators include organic peroxides and azo
compounds. During use when the preferred sealants based on blends
of epoxy-containing material and polyacrylate components softens,
flows and fills gaps in the surface to be sealed, the epoxy resin
and the polyacrylate component form a homogenous, single phase
system, as evidenced by a lack of macroscopic phase separation to
the unaided human eye.
[0090] The relative amounts of the different ingredients are
selected to balance ultimate tensile strength and heat resistance,
on the one hand, with flexibility and green strength build-up on
the other hand. For example, increasing the amount of epoxy resin
increases ultimate tensile strength and heat resistance, while
decreasing flexibility and rate of green strength build-up.
Conversely, increasing the amount of polyester or polyacrylate
increases flexibility and rate of green strength build-up, while
decreasing ultimate tensile strength and heat resistance.
[0091] In the case of epoxy-polyacrylate and epoxy-polyester
blends, the compositions typically include from 0.01 to 95 parts
per 100 parts total of the epoxy-containing material and,
correspondingly, from 99.99 to 5 parts of the polyester or
polyacrylate component. More preferably, the compositions include
from 0.1 to 80 parts of the epoxy-containing material and,
correspondingly, from 99.9 to 20 parts of the polyester or
polyacrylate component. Most preferably, the compositions include
from 0.5 to 60 parts of the epoxy-containing material, and,
correspondingly, from 99.5 to 40 parts of the polyester or
polyacrylate component.
[0092] Other melt-flowable thermosettable compositions useful for
sealant layer 12 include urethane-based materials such as
moisture-curable urethanes that may also be hot-melt compositions.
Such compositions often comprise one or more polyisocyanates (e.g.,
diisocyanates such as 4,4'-diphenylmethylene diisocyanate, toluene
diisocyanate, isophorone diisocyanate, or hexamethylene
diisocyanate, including isocyanate derivatives of these materials),
one or more polyhydroxy-functional materials (e.g, polyester or
polyether polyols including polycaprolactones), optionally a
catalyst for the moisture curing reaction (e.g, dibutyltin
dilaurate), and optionally a variety of additives or adjuvants
(e.g., fillers, colorants, beads, bubbles, fibers, plasticizers,
tackifiers, flow control agents, thixotropes, adhesion promoters,
etc.) that do not materially interfere with the moisture curing
reaction.
[0093] Sealant layer 12 may also be formed from a thermoplastic
composition. Examples of suitable thermoplastic compositions
include polyesters, thermoplastic elastomer block copolymers (e.g.,
styrene-butadiene- or styrene-isoprene-based block copolymers),
phenoxy resins, polyurethanes, silicones, and polyamides.
Polyesters, block copolymers and polyurethanes are particularly
preferred thermoplastics. Preferably, thermoplastic compositions
used in the sealant layer are provided as homogenous, single phase
materials that do not include a dispersed phase such as
cross-linked particles. Thermoplastic compositions selected for
sealant layer 12 preferably display a softening temperature (as
measured by a ring and ball softening test) that is greater than
the service temperature for the ultimate construction into which
the sealant-bearing article will be incorporated. The service
temperature for the ultimate construction refers to the maximum
temperature that the ultimate construction is expected to be
exposed to under ordinary use conditions.
[0094] Preferred compositions for sealant layer 12 are sealant
compositions that resist flow, and thus substantially retain their
shape, when heated to a temperature above the softening temperature
of the sealant, and for thermosetting sealant compositions, a
temperature that is less than (a) in the case of thermally
activated curing agents, the thermal activation temperature of the
curing agent or (b) in the case of photo-active curing agents, the
thermal decomposition temperature of the curing agent, until
subjected to pressure on the order of the pressure applied during
installation as the tape-bearing substrate is pressed into contact
with the other substrate. Under the influence of heat and applied
pressure, these compositions undergo controlled flow to conform and
functionally seal against uneven surfaces.
[0095] The softening temperature represents the minimum temperature
at which the composition is sufficiently malleable such that it can
be mounted to and held in place on a substrate. The softening
temperature is a function of the particular sealant composition. In
the case of crystalline or semi-crystalline component-containing
sealing compositions, this generally corresponds to the melting
temperature of this component. Typically, the upper temperature
limit is on the order of about 200.degree. C.
[0096] To determine whether any particular sealant composition
meets these performance criteria, the composition is subjected to
the test procedure described in further detail in the "Examples"
section below. Briefly, this test involves placing a sample of the
composition on a plate maintained at an angle in an oven, heating
the sample to the desired temperature, and observing the extent to
which the sample loses its initial shape and flows down the surface
of the plate within a set period of time.
[0097] Examples of compositions meeting these requirements include
both thermoplastic and thermosettable materials. In the case of the
latter, the compositions may incorporate one or more photo-active
curing agents, thermally activated curing agents, or combinations
thereof, with the use of photo-active curing agents being
preferred.
[0098] Particular compositions meeting these requirements include
the epoxy/polyester and epoxy/polyacrylate compositions described
above, but particularly designed or formulated such that melt-flow
does not occur under the influence of heat and gravity alone, but
instead requires applied pressure as well. One useful formulation
involves including one or more thixotropic agents into the
composition in an effective amount; i.e., an amount necessary to
achieve the desired rheological properties. In general, the total
amount of thixotropic agents is no greater than about 20% by
weight, based upon the total weight of the uncured sealant
composition, preferably no greater than about 10% by weight, more
preferably no greater than about 5% by weight, and most preferably
in the range of about 3-5% by weight.
[0099] Suitable thixotropic agents do not materially interfere with
cure, in the case of thermosetting compositions, or otherwise cause
degradation of the composition. Representative examples of
thixotropic agents include particulate fillers, beads (which may be
of the glass, ceramic or polymeric type), bubbles (which may be of
the glass, ceramic or polymeric type), and chopped fibers, as well
as combinations thereof. Suitable particulate fillers include,
e.g., hydrophobic and hydrophilic silica, calcium carbonate,
titania, bentonite, clays and combinations thereof. Suitable fibers
include polymeric fibers (e.g., aromatic polyamide, polyethylene,
polyester and polyimide fibers), glass fibers, graphite fibers, and
ceramic fibers (e.g., boron fibers).
[0100] Other materials that can be incorporated into sealant layer
12 include, for example, stabilizers, antioxidants, plasticizers,
tackifiers, flow control agents, adhesion promoters (e.g., silanes
and titanates), colorants, and other fillers.
[0101] Bonding layer 16 is preferably in the form of a continuous
layer. The width of bonding layer 16 is application-dependent. In
general, however, the width of bonding layer 16 is preferably no
greater than the width of core layer 14. In addition, both single
and multilayer bonding compositions are envisioned.
[0102] In use, bonding layer 16 is disposed between core layer 14
and the surface of the substrate to which tape 10 is affixed. The
purpose of bonding layer 16 is to enhance adhesion between the
substrate and core layer 14. It may be integral with tape 10, as
shown in FIG. 1, or may be provided separately on the face of the
substrate prior to affixing tape 10 to the substrate. It is
particularly useful when the substrate is glass.
[0103] The thickness of bonding layer 16 is selected based upon the
particular application for which the tape is to be used. In
general, however, the thickness of bonding layer 16 is no greater
than about 500 microns, preferably no greater than about 250
microns, and more preferably no greater than about 125 microns.
[0104] Suitable materials for bonding layer 16 are tacky at the
installation temperature. Both thermoplastic and thermosetting
materials may be used, The bonding layer is ordinarily selected so
as to have, as compared to the sealant layer, a different
composition, thickness or both. The choice of a particular material
for bonding layer 16 depends on the substrate to which tape 10 is
affixed. For example, in the case of glass substrates,
thermosetting materials are preferred, whereas in the case of
encapsulated glass substrates, in which a polymer encapsulates the
peripheral edge of the glass, it is preferred to use thermoplastic
bonding materials.
[0105] The bonding layer is designed to have a relatively high
ultimate tensile strength following cure (in the case of
thermosettable materials) or upon cooling (in the case of
thermoplastic materials), without being brittle, to promote
localized failure in the core layer. The particular minimum tensile
strength value is application-dependent. In general, however,
tensile strengths are on the order of at least about 3.5 MPa,
preferably at least about 5.2 MPa, and more preferably at least
about 6.9 Mpa when measured according to the test procedure
described in the "Examples" section below. For example, in the case
of windshields installed in motor vehicles, the ultimate tensile
strength of the bonding layer preferably is greater than about 3.5
MPa.
[0106] Thermosetting materials may incorporate a photo-active
curing agent (i.e., photo-curable materials) or a thermally
activated curing agent (i.e., thermally curable materials).
Preferably, bonding layer 16 cures under conditions different from
the conditions under which sealant layer 12 cures. For example, if
both sealant layer 12 and bonding layer 16 are photo-curable
materials, the wavelength of radiation needed to initiate cure of
layer 12 differs from that needed to initiate cure of layer 16.
Similarly, if both sealant layer 12 and bonding layer 16 are
thermally curable materials, they cure at different temperatures.
Bonding layer 16, for example, is typically formulated such that it
cures within the range 90-200.degree. C., preferably within the
range 120-170.degree. C., and more preferably within the range
140-160.degree. C. It is also possible to use a photo-curable
material for layer 12 and a thermally curable material for layer
16, and vice versa.
[0107] Examples of suitable materials for bonding layer 16 include
epoxy/polyacrylate blends as described, e.g., in Kitano et al.,
U.S. Pat. No. 5,086,088; epoxy/amorphous polyester blends;
polyolefin adhesives (e.g., polyethylene, polypropylene,
polyhexene, polyoctene, and blends and copolymers thereof;
ethylene-vinyl monomer (e.g., ethylene-vinyl acetate) copolymer
adhesives; epoxy adhesives; silicone adhesives; silicone-acrylate
adhesives; acrylic adhesives; rubber adhesives (e.g., butyl
rubber); and adhesives based upon thermoplastic elastomer block
copolymers (e.g., styrene-butadiene-styrene,
styrene-isoprene-styrene, or styrene-ethylene-propylene-styrene
block copolymers). These materials may be provided in film or bulk
form, and may be supplied as hot melt materials. Depending upon the
substrate to which the bonding layer will be adhered, the use of a
primer may be advantageous in promoting adhesion. An example of a
suitable commercially available material is 3M Company's Structural
Bonding Tape No. 9214.
[0108] Other materials that can be incorporated into bonding layer
16 include, for example, stabilizers, antioxidants, plasticizers,
tackifiers, flow control agents, adhesion promoters (e.g., silanes
and titanates), colorants, thixotropes, and other fillers.
[0109] Optional, temporary, protective liner 18, if included,
protects bonding layer 16 (if present) or core layer 14 from
damage, actinic radiation exposure, and dirt or other contaminants
until article 10 is intended for use and is typically removed
shortly before attaching article 10 to a substrate. Liner 18 may
comprise a variety constructions, including those conventionally
used to protect adhesive surfaces. For example, the liner may be in
the form of a paper or polymeric web having a release material such
as a polyolefin (e.g., polyethylene, polypropylene, etc.), silicone
or fluorosilicone on a surface thereof that bears against the
bonding layer or the core layer. Liners that are slightly tacky can
be used to protect non-tacky surfaces.
[0110] Manufacture
[0111] Multi-layer articles according to the invention may be
readily prepared in many ways. For example, the ingredients for the
sealant composition may be melted and stirred in a suitable mixing
vessel (e.g., a batch mixer, an extruder, etc.) at an elevated
temperature low enough to avoid activating any thermally activated
curing agent or decomposing any photo-active curing agent present
in the sealant composition. After mixing, the sealant composition
may be formed into its final shape by a variety of different
methods. For example, the sealant composition can be coated onto a
release liner using a heated knife coater. Alternatively, the
sealant composition ingredients may be compounded in an extruder
and then extruded through a die having a desired profile to produce
a shaped strip of sealant; i.e., a strip having the desired
cross-sectional shape. In another approach, the composition can be
extruded as a mass and delivered between a pair of motor-driven
chilled rolls spaced apart a predetermined distance to form a flat
sheet of the sealant composition that may be subsequently
calendared to the desired thickness. In another approach, a flat
die may be coupled to the extruder to extrude the sealant
composition into a flat sheet, either onto a release liner or
directly onto a separately provided core layer. A structure can be
imparted to a major surface of the sealant layer by extruding the
sealant sheet between a pair of nip rolls, at least one of which is
embossed with the desired pattern. A sheet of the sealant
composition can also be embossed at any subsequent time by heating
the sheet (if necessary) and pressing the sheet with an embossing
roll (which may be heated or unheated) carrying the desired
pattern.
[0112] In one preferred method of manufacture, where the sealant
composition comprises an epoxy-containing material and a polyester
component, these ingredients are compounded using a twin screw
extruder adjusted to provide an appropriate barrel temperature
profile. Typically, the feed end of the extruder is set at a
relatively low temperature, e.g., about 60 to 70.degree. C., and
the temperature is increased along the length of the barrel such
that the temperature is high enough to mix the sealant composition
ingredients into a uniform blend, but low enough to avoid
activating any curatives at the die end of the extruder, e.g.,
about 60 to 110.degree. C. Residence time within the extruder
should also be balanced with the extruder temperature profile so as
to avoid activating any curatives. Preferably the extruder has one
or more vent ports along the barrel toward the die end so that a
vacuum can be applied to remove entrapped air and moisture. The
composition is extruded into a calendar nip or through an
appropriately shaped die, which results in a sheet of the sealant
composition having the desired thickness and width.
[0113] Batch mixing techniques may also be employed in preparing
the sealant compositions used in the invention and for certain
sealants (e.g., those that are moisture-curable) such approaches
may be preferred.
[0114] The core layer can also be prepared in many ways, depending
on its composition.
[0115] For example, in a thermosettable acrylic core layer,
appropriate acrylate and/or methacrylate monomers are mixed
together and then combined with a suitable photo- or
thermally-activated polymerization initiator. The monomer
composition is then preferably sparged with an inert gas such as
nitrogen to eliminate most of the oxygen from the composition, and
then either exposed to an ultraviolet light source or heated to
initiate polymerization of the monomer mixture. Once the desired
viscosity has been reached, the reaction is quenched by either
removing the light source, cooling the composition, sparging with
oxygen, or a combination thereof, resulting in a viscous
polymer/monomer mixture having a syrup-like consistency.
[0116] The polymer/monomer mixture may be blended with various
ingredients such as additional initiator, particulate additives
such as fumed silica (of the hydrophilic and/or hydrophobic type),
fillers such as glass, ceramic or polymeric bubbles, or glass,
ceramic or polymeric beads, thixotropes, colorants, stabilizers,
antioxidants, plasticizers, tackifiers, surfactants and other flow
control agents, adhesion promoters (e.g., silanes and titanates),
and crosslinking agents. This composition is then degassed and/or
sparged with an inert gas such as nitrogen, and then coated between
a pair of release liners (e.g., silicone-coated, biaxially-oriented
polyethylene terephthalate films). For compositions that are to be
further polymerized by exposure to ultraviolet radiation, the
release liners are preferably transparent to ultraviolet
radiation.
[0117] Alternatively, the composition may be pumped to a frother
where an inert gas such as nitrogen is introduced into the
composition creating a cellular foam mixture that is subsequently
coated between a pair of release liners, such as those just
described. The uniformity, density, cell size, tensile strength and
elongation of the final foam product are controlled by the
selection and amount of surfactant, the nitrogen flow rate, and the
pressure in the frother, as described in the technical
literature.
[0118] If the composition is to be polymerized with actinic
radiation, the composite construction comprising the
polymer/monomer syrup between the pair of release liners is, for
example, irradiated by an ultraviolet light source, preferably of
low intensity (e.g., below about 20 milliWatts/square centimeter as
measured with NIST units, more preferably below about 10
milliWatts/square centimeter). The amount of radiation energy
required to polymerize the composition varies depending upon the
thickness and its chemical make-up, but typically ranges from about
200 to 2,000 millijoules. Preferably, sufficient radiation is used
to reduce the volatile monomer content to less than 5%, and more
preferably to less than 2% by weight of the entire composition.
Alternatively, the composition can be polymerized with heat.
[0119] If the polymerization reaction is exothermic, temperature
control of the composite construction (preferably to less than
85.degree. C.) is desired. This can be accomplished in a number of
ways including blowing cool air against the faces of the composite
construction, immersing the composite construction in a water bath,
running the composite construction over cooling platens, and the
like.
[0120] In the case of a urethane-based core layer, the core layer
components (whether from a one- or a two-part system) are mixed
just prior to coating the resulting composition between two release
liners, such as those described previously. A small amount of heat
may be used to accelerate the curing reaction, although many
urethanes will cure at room temperature. Alternatively, urethane
compositions, after mixing, can be coated between a release liner
and a sealant layer, between a sealant layer and a bonding layer,
or between a release liner and a bonding layer. When the urethane
composition is applied directly to a sealant layer and/or a bonding
layer, additional layers, e.g., tie layers advantageously may not
be needed.
[0121] Polyethylene and ethylene vinyl acetate-based foams may also
be used and are typically produced by extruding a resin composition
from an extruder and foaming the material before or after
crosslinking.
[0122] The bonding layer may also be prepared in many ways.
Pressure-sensitive adhesive bonding layers are formed from
compositions that can be prepared by solvent, emulsion or
solventless processes. For solvent- and emulsion-based systems, the
compositions are coated onto a release liner (such as those
described above) and heated in an oven to evaporate the solvent or
the water and form an adhesive film. Such adhesives are well-known
and described in, for example, U.S. Pat. No. Re. 24,906 (Ulrich).
For solventless compositions, a pre-polymeric composition is coated
onto a release liner and exposed to an energy source to form an
adhesive film. These types of processes are described in, for
example, U.S. Pat. Nos. 4,181,752 (Martens et al.), and 5,086,088
(Kitano et al.).
[0123] In a preferred embodiment, a bonding layer composition is
prepared by mixing acrylic monomers such as n-butyl acrylate and
N-vinylcaprolactam, an epoxy resin such as diglycidylether of
Bisphenol A, a-photoinitiator, a thermal curative, and fumed silica
in a high speed Cowles mixer. The composition is then coated
between polyethylene terephthalate release liners and exposed to an
ultraviolet radiation source, similar to that described above for
the manufacture of acrylic foam core layers, to produce a latently
reactive, curable pressure sensitive adhesive.
[0124] One approach is particularly useful when an acrylic foam
core layer is to be combined with a solventless pressure sensitive
acrylic adhesive bonding layer of the type described above. The
composition for the acrylic foam core layer may be coated onto an
ultraviolet radiation-transparent release liner as described above,
and then the composition for the pressure-sensitive acrylic
adhesive bonding layer is coated onto the core layer composition. A
second ultraviolet radiation-transparent release liner is then
placed over the bonding layer composition and the entire
construction is exposed to ultraviolet light to concurrently cure
both the acrylic foam core layer and the pressure-sensitive acrylic
adhesive bonding layer thereby yielding a finished composite. It is
also contemplated that the bonding layer and the core layer, the
core layer and the sealant layer, or the core layer, the bonding
layer, and the sealant layer can be made simultaneously using, for
example, the techniques described in conjunction with the
manufacture of urethane-based core layers.
[0125] The multi-layer articles of the invention may also be
produced by laminating a previously prepared sealant layer, core
layer and bonding layer (if provided). For example, the bonding
layer and/or the sealant layer can be readily laminated to the core
layer under the influence of pressure to produce a finished tape.
When the core layer, sealant layer, and bonding layer are each made
separately, adhesion between these layers may be enhanced through
the use of primers or tie layers. The primer or tie layer can be
applied by extrusion coating a compatible material onto either the
sealant layer or the core layer, coating a primer onto either
layer, optionally drying the primer or tie layer, and then pressing
the layers together to form a multi-layer article according to the
invention.
[0126] In another embodiment, a sealant layer can be extruded or
coated directly onto a core layer.
[0127] Once the tape has been fabricated a release liner may
optionally be laminated to protect the exposed surfaces of the
sealant layer and/or the core layer or the bonding layer (if
provided). The tape may be converted into the desired final form
by, for example, slitting it to the desired width and winding it up
into roll form and around a suitable plastic or paper core if
needed. Alternatively, the tape can be slit or otherwise cut into
discrete lengths or die cut into desired shapes.
[0128] Use
[0129] The above-described tapes can be used to establish a seal
between a variety of substrates. For the sake of simplicity,
however, the sealing process will be described in the context of
installing a glass windshield in a motor vehicle.
[0130] Referring to FIGS. 2 and 3, tape 10 is initially affixed to
one face 22 of glass windshield 20 through bonding layer 16 such
that the tape substantially surrounds the perimeter of face 22 and
smoothly adheres to the glass without wrinkling, puckering or
gapping as the tape traverses the approximately ninety degree bends
at the corners of the windshield. This arrangement avoids forming
stress concentration points previously associated with the use of
discontinuous spacers. If the bonding layer is not tacky at room
temperature, it is then activated to bond tape 10 permanently to
the glass, preferably without activating sealant layer 12. The
particular activation method used depends on the composition of the
sealant and bonding layers. Examples of suitable activation methods
include thermal and actinic radiation (e.g., ultraviolet or visible
radiation). In the case of thermal radiation, either the tape, the
glass, or both, may be heated. Because the sealant layer is not
activated, the resulting tape-bearing windshield can be packed or
racked in close proximity with other tape-bearing windshields
without transferring sealant to a neighboring windshield. The tape
also prevents the windshields from bumping into each other which
eliminates costly packaging materials that space adjacent racked or
packed windshields from each other (e.g., polymeric foam or
cellulosic spacers) and which may require separate disposal or
recycling.
[0131] The next step is to heat the sealant, e.g., by exposing it
to a bank of heat lamps, to the point where the sealant softens but
does not flow. As represented by FIGS. 4 and 5, the windshield
containing the heated, softened sealant is then installed in the
frame 24 of a motor vehicle 26. It is also possible to heat the
sealant after installing it in the motor vehicle frame to soften
the sealant. During installation, pressure is applied that causes
the softened sealant to flow and "self level" with the core layer
12 relative to the uneven surface of the vehicle. The sealant flows
away from high spots and fills in recessed areas such as spot welds
and cavities, creating an effective seal. In severely distorted
metal areas, the core layer 12 compresses upon itself and may be
permanently deformed in the process of creating a seal with the
uneven surface.
[0132] Following intimate contact between the sealant layer and the
vehicle frame, the heat sink of the large metal vehicle mass
effectively quenches the sealant layer, allowing it to solidify
rapidly, recrystallize (in the case of crystalline or
semi-crystalline component-containing sealant compositions), and
form a durable, permanent bond.
[0133] A variation of this process involves the use of photocurable
sealant layers (i.e., sealant layers that incorporate a
photo-active curing agent). Using a photocurable sealant
composition is advantageous because the tape can be affixed to the
windshield and run through a glass manufacturing autoclave cycle to
activate the bonding layer, while at the same time softening the
sealant composition without causing it to flow. After leaving the
autoclave, the construction is cooled, causing the softened sealant
layer to re-solidify. Next, the sealant composition is activated,
e.g., by exposure to heat followed by actinic radiation, after
which the tape-bearing windshield is placed in the vehicle frame.
The radiation simultaneously softens and initiates cure of the
sealant composition. Once installed, the heat sink created by the
vehicle body effectively quenches the sealant layer, causing it to
re-solidify and, in the case of crystalline or semi-crystalline
component-containing compositions, to re-crystallize. At this
point, the green strength of the sealant layer is sufficiently high
that a person can drive away in the vehicle even though the sealant
continues to cure.
[0134] In the case of photocurable sealant compositions, it is also
necessary to protect the composition from premature activation,
e.g., during storage and shipping. This may be accomplished, for
example, by covering the sealant composition with a
radiation-blocking release liner. Alternatively, the entire
tape-bearing construction can be stored in a radiation-blocking
container.
[0135] Although it is preferable to include the sealant layer, core
layer, and bonding layer in the form of a single integral tape, it
is also possible to apply these materials separately, or in various
combinations with each other, to the glass surface. For example, it
is possible to apply a tape featuring the core layer and the
bonding layer to the glass surface, followed by application of a
separate sealant layer. Alternatively, the bonding layer may be
provided in the form of a primer applied to the glass surface,
after which a two-layer tape (containing the sealant layer and the
core layer) is affixed to the primed surface.
[0136] Although in the case of substrates such as windshields it is
preferable to apply the tape to a face of the substrate, it is also
possible to apply the tape around the edge 30 of a substrate 32, as
shown in FIGS. 6 and 7, such that the tape 10 substantially
encircles the substrate. Such constructions are useful, e.g., in
architectural applications for bonding the substrate within a
groove such as a window frame.
[0137] In addition to windshields, in which a seal is established
between a face of the windshield and the frame of a motor vehicle,
it is also possible to seal a substrate 40 bearing a tape 10
according to the invention within a U-shaped bracket 42, as shown
in FIG. 8.
[0138] The invention will now be described further by way of the
following non-limiting examples.
EXAMPLES
[0139] Unless otherwise specified the materials used in these
examples may be obtained from standard commercial sources such as
Aldrich Chemical Co. of Milwaukee, Wis. All amounts used in the
examples are in parts by weight unless otherwise specified. Sealant
Layers were prepared by calendering the corresponding Sealant
Composition to a desired thickness. Thus Sealant Layer A is
composed of Sealant Composition A, Sealant Layer B is composed of
Sealant Composition B, and so on. All Sealant Layers, Core Layers
and Bonding Layers were nominally 1.0 mm thick unless otherwise
specified. The following list contains commercial sources for
materials employed in the examples that follow. The Fusion Systems
Processor (lamp housing and conveyor apparatus) was fitted with a V
bulb unless otherwise specified.
[0140] Epoxy Resin A is a Bisphenol A endcapped aliphatic epoxy
resin, as described in Example 1 of U.S. Pat. No. 5,407,978 (Bymark
et. al.).
[0141] Primer Composition A is: 2.45 parts Nipol.TM. 1002, 1.23
parts Epon.TM. 828, 2.05 parts Versamid.TM. 115, 42.20 parts methyl
ethyl ketone, 50.84 parts toluene, 1.23 parts 1-butanol.
[0142] Metallocene Catalyst A is
Cp(Xylenes)Fe.sup.+SbF.sub.6.sup.-, also described as:
(eta.sup.6-xylenes)(eta.sup.5-cyclopentadienyl)iron (1+)
hexafluoroantimonate as disclosed in U.S. Pat. No. 5,089,536
(Palazzotto). (Cp=cyclopentadiene.)
[0143] Scotchkote.TM. 215, FX-512, K15 glass bubbles (250 mesh),
and Auto Glass Urethane Windshield Adhesive No. 08693 urethane
paste sealant were obtained from 3M Company of St. Paul, Minn.
[0144] E-coated steel panels (ED 5100), and painted stell panels
clear coated with DCT 5000, DCT 5002 and Stainguard.TM. IV were
obtained from Advanced Coating Technologies, Inc. of Hillsdale,
Mich.
[0145] Dicyandiamide (CG-1200) and Curezol.TM. 2MZ-Azine were
obtained from Air Products and Chemicals, Inc. of Allentown,
Pa.
[0146] n-Butyl acrylate, N-vinylcaprolactam were obtained from BASF
Corp. of Mount Olive, N.J.
[0147] Vitel.TM. 5833B was obtained from Bostik of Middleton,
Mass.
[0148] Cab-O-Sil.TM. M5 was obtained from Cabot Corp. of Boston,
Mass.
[0149] Irganox.TM. 1010 was obtained from Ciba Specialty Chemicals
of Ardsley, N.Y.
[0150] Aerosil.TM. R972 was obtained from DeGussa Corp. of
Ridgefield Park, N.J.
[0151] Voranol.TM. 230-238 was obtained from Dow Chemical Co. of
Midland, Mich.
[0152] Isocryl.TM. EP550, Octaflow.TM. ST 70 and Oxymelt.TM. A-1
were obtained from Estron Chemical, Inc. of Calvert City, Ky.
[0153] Melinex.TM. 054 is a treated biaxially oriented polyester
film available from ICI Americas of Wilmington, Del.
[0154] Fusion Systems Processor and accessories were obtained from
Fusion Systems Corp. of Rockville, Md.
[0155] Versamid.TM. 115 was obtained from Henkel Corp. of Ambler,
Pa.
[0156] Dynapol.TM. S1402, Dynapol.TM. S13 13, Dynapol.TM. S1359,
Dynacoll.TM. 7130, Synthetic Resin SK, Hydrosil.TM. 2627, Synthetic
Resin AP, Synthetic Resin Calif., Synthetic Resin LTH, Polyester A
(a hydroxyl functional, semi-crystalline copolymer of 50 wt. %
butanediol, 23 wt. % terephthalic acid, and 27 wt. % sebacic acid,
with a melting point of 116 C., a glass transition temperature of
-40.degree. C., and a melt flow rate at 160.degree. C. of 250 g/10
minutes), were obtained from Huls America Inc. of Somerset,
N.J.
[0157] Santicizer.TM. 278 was obtained from Monsanto Co. of St.
Louis, Miss.
[0158] Penn Color 9B117 pigment was obtained from Penn Color of
Doylestown, Pa.
[0159] Unilin.TM. 700 wax was obtained from Petrolite Corp. of St.
Louis, Miss.
[0160] #5 Meyer rods (wire wound rods) were obtained from R & D
Specialties of Webster, N.Y.
[0161] KB-1 and SarCat.TM. CD 1012 were obtained from Sartomer Co.
of Exton, Pa.
[0162] Epon.TM. 1001, Epon.TM. SU-8 and Epon.TM. 828 were obtained
from Shell Chemical Co. of Houston, Tex.
[0163] Benzoflex.TM. S-404 was obtained from Velsicol Chemical
Corp. of Rosemont, Ill.
[0164] Nipol.TM. 1002 was obtained from Zeon Chemicals, Inc. of
Louisville, Ky.
[0165] Anodized aluminum panels were obtained from Hiawatha Panel
& Name Plate Co., Inc., Minneapolis, Minn.
Test Methods
[0166] 45.degree. Flow Test
[0167] An E-coated panel was cleaned by spraying with 50% aqueous
isopropanol and wiping dry, allowing sufficient time to ensure
complete drying. The sample to be measured (typically 14.5 mm by
25.4 mm) was lightly adhered to an E-coated panel so that the
narrow edge of the sample was pointing down the panel. The panel
was then placed in an oven at a 45.degree. incline for 12 minutes
at 177.degree. C. unless otherwise specified. The sample was then
removed from the oven and allowed to cool to room temperature. Flow
was measured as the distance ( in mm) the sample had flowed
relative to its initial position.
[0168] Tensile and Elongation Test
[0169] Tensile measurements were made in the usual fashion with
attention to the following parameters. Samples were cut to size
using ASTM method D-412, Die C. The samples were then conditioned
under constant temperature (23.+-.2.degree. C.) and humidity
(50.+-.10% relative humidity) for at least 24 hours after
preparation and before testing. Tensile strength and elongation
were measured using an Instron tensile tester using a jaw gap of
50.8 mm and a crosshead speed of 508 mm/minute. Peak tensile
strength ( in MPa) and optionally % elongation at peak were
recorded.
[0170] Overlap Shear Test
[0171] A sealant composition was laminated between anodized
aluminum and E-coated aluminum coupons both 25.4 mm by 76.2.mm that
had been cleaned with 50% aqueous isopropanol as follows: a 12.7 mm
by 25.4 mm sample of sealant was attached flush to the narrow edge
of both coupons so that the overall construction was about 63.5 mm
in length. The laminate was heated in an oven at 140.degree. C. for
25 minutes while under approx. 2.3 kg compressive force, unless
otherwise specified. Samples were then conditioned under constant
temperature and humidity (23.+-.2.degree. C. and 50.+-.10% relative
humidity) for at least 24 hours after preparation and before
testing.
[0172] Overlap shear was measured using an Instron tensile testing
apparatus using a crosshead speed of 50.8 mm/minute, and a jaw gap
of 50.8 mm. The maximum force before breakage of the sample and the
failure mode (e.g., cohesive, adhesive, mixed) were noted.
Example 1
[0173] This example describes the preparation of Bonding Layer A. A
solution was prepared by mixing of 29 g n-butyl acrylate (BA) and
29 g N-vinylcaprolactam (NVC) and heating at about 49.degree. C. To
this solution, an additional 42 g of BA and 0.05 g of hexanediol
diacrylate were added. This acrylate monomer solution, 45 g of
diglycidyl ether of bisphenol A (Epon.TM. 828), and 25 grams of
diglycidyl ether oligomer of bisphenol A (Epon.TM. 1001) were
placed in a glass jar. The jar was sealed and placed on rollers at
ambient temperature (about 21.degree. C.) until a uniform adhesive
solution resulted. To this epoxy/acrylate solution (170.05 parts),
7 g CG-1200, and 2.7 g of an accelerator (Curezol.TM. 2MZ-Azine)
were added and mixed with at Cowles blade mixer at high speed,
while keeping the temperature below about 37.degree. C., for 15
minutes. In the final step, 0.24 g of benzil dimethyl ketal
photoinitiator (KB-1), 0.1 g of Irganox.TM. 1010 antioxidant, 0.38
g of Penn Color 9B117 pigment, and 8 g of Cab-O-Sil.TM. M5 silica
were added and mixed to form a uniform mixture. The adhesive
mixture was degassed, and then coated to a thickness of 0.508 mm
between two silicone release material treated polyester films. The
sandwiched coating of adhesive was exposed to ultraviolet light
having a majority of its emissions between 300 and 400 nm with a
peak emission at 351 nm to form a pressure sensitive adhesive tape.
The adhesive was exposed to 350 mJ/cm.sup.2 (NIST units) on the top
and bottom, with a total energy of approx. 700 mJ/cm.sup.2. The
intensities were 4.06 mW/cm.sup.2 on the top and 4.03 mW/cm.sup.2
on the bottom of the adhesive.
[0174] Examples 2-7 describe the preparation of various Core
Layers
Example 2
[0175] A composition was prepared by mixing 87.5 parts isooctyl
acrylate, 12.5 parts acrylic acid, and 0.04 parts of a
photoinitiator (benzil dimethyl ketal available as Irgacure.TM. 651
from Ciba Geigy). The mixture was exposed to low intensity
ultraviolet radiation (described below) to a viscosity of about
2200 centipoise. Then an additional 0.19 part of benzil dimethyl
ketal was added as well as 0.55 part 1,6-hexanedioldiacrylate, 8
parts K15 glass bubbles, and 2 parts of hydrophobic silica
(Aerosil.TM. R972). The composition was mixed until it was uniform
throughout, degassed, and then pumped into a 90 mm frother
(available from E.T. Oakes, Hauppage, N.Y.) operating at about 300
to 350 rpm. Concurrently, and continuously, nitrogen, black pigment
(PennColor 9B117), and approximately 1.5 parts of a 60/40 mixture
of surfactant A/surfactant B were fed into the frother per 100
parts of the total composition. The nitrogen was controlled to
provide the desired foam density. Surfactant A was
C.sub.8F.sub.7SO.sub.2N(C.sub.2H.sub.5)(C.sub.2-
H.sub.4O).sub.7CH.sub.3 and surfactant B was a 50% solids solution
in ethyl acetate of the fluoroaliphatic oligomer of Example 2 of
U.S. Pat. No. 3,787,351. The black pigment was added in an amount
to provide a finished product L value of about 32 as measured with
a HunterLab colorimeter (Color `L` calorimeter and a D25 Optical
Sensor, both available from HunterLab Associates, Reston Va.).
[0176] The frothed mixture was delivered under a pressure of 205
kilopascals to the nip of a roll coater to a thickness of about 1
mm between a pair of sheets of transparent, biaxially-oriented
polyethylene terephthalate, the facing surfaces of which had
release coatings, to produce a composite. The tubing was partially
constricted by a clamp to provide the desired level of pressure in
the frother. The composite emerging from the roll coafer was
irradiated from both the top and bottom with banks of Sylvania
fluorescent black light bulbs, 90% of the emissions of which were
between 300 and 400 nm, with a maximum of 351 nm. The composite was
successively exposed to the bulbs at an intensity of 2.65
milliWatts/square centimeter (mW/cm.sup.2) and a total energy of
165.4 millijoules per square centimeter (mJ/cm.sup.2) each from the
top and bottom, then likewise to an intensity of 2.70
mW/cm.sup.2and a total energy of 168.5 mJ/cm.sup.2, and then
likewise to an intensity of 5.90 mW/cm.sup.2 and a total energy of
516.8 mJ/cm.sup.2. Light measurements were measured in MST units.
The cured core (i.e., Core Layer A) between the release liners had
a density of about 0.64 g/cm.sup.3.
Example 3
[0177] Core Layer B was prepared as described above for Core Layer
A except that the processing conditions were varied as follows. The
composite was successively exposed to the Sylvania fluorescent
black light bulbs at an intensity of 4.3 mW/cm.sup.2 for a total
energy of 160.7 mJ/cm.sup.2 each from the top and bottom, and then
an intensity of 5.1 mW/cm.sup.2 for a total energy of 892.6
mJ/cm.sup.2. The cured core between the release liners had a
density of about 0.64 g/cm.sup.3.
Example 4
[0178] Core Layer C was prepared as described above for Core Layer
A except that the pigment was a mixture of 77 parts of a 20%
stannous chloride and 80% polyoxypropylenediol, and 23 parts of 20%
carbon black in 80% polyoxypropylenediol and the amount of pigment
was adjusted to provide a final core color L value of 45. The
processing conditions were also varied as follows, The composite
was successively exposed to the Sylvania fluorescent black light
bulbs at an intensity of 1.25 mW/cm.sup.2 for a total energy of
73.5 mJ/cm.sup.2 each from the top and bottom, then likewise to an
intensity of 1.50 mW/cm.sup.2 for a total energy of 88.2
mJ/cm.sup.2, and then likewise to an intensity of 4.3 mW/cm.sup.2
for a total energy of 353.5 mJ/cm.sup.2. The cured core between the
release liners had a density of about 0.64 g/cm.sup.3.
Example 5
[0179] Core Layer D was prepared by laminating two layers of Core C
together, 2.0 mm total thickness.
Example 6
[0180] Core Layer E was prepared by laminating three layers of Core
C together, 3.0 mm total thickness.
Example 7
[0181] Core Layer F was prepared by extruding Auto Glass Urethane
Windshield Adhesive No. 08693 from a caulk gun onto a silicone
release material coated polyester liner and coated into a film 5 mm
in thickness.
[0182] Examples 8 through 28 describe the preparation of various
sealant layers and compositions useful in the invention.
[0183] Sealant Layers A through C were extruded onto a polyester
carrier film having a double sided silicone release coating, and
fed through nip rollers to achieve the desired layer thickness.
Example 8
[0184] This example describes the preparation of Sealant Layer A. A
2:1 ratio of Dynapol.TM. S1402 polyester and Scotchkote.TM. 215
powder coating resin was melt mixed in a twin screw extruder and
calendered to a thickness of 1.5 mm. Representative extruder
operating conditions were: Screw RPM=100, Melt Temp=103.9.degree.
C., Zone 1 Temp=81.1.degree. C., Zone 2 Temp =85.5.degree. C. A
45.degree. flow test was performed on 25.4 mm.times.25.4 mm
samples. Test conditions were 177.degree. C. for 12 minutes. Reflow
was also done by allowing the samples to cool to room temp for 30
minutes and then placing them in the oven again. Flow was 42 mm.
There was no flow after 30 minutes, indicating the formation of a
thermoset material.
Example 9
[0185] This example describes the preparation of Sealant Layer B.
Dynapol.TM. S1359 polyester (60 parts by volume), and a powder
mixture of Epon.TM. 1001 epoxy resin (10 parts by volume),
dicyandiamide (7 parts by volume), and Curezol.TM. 2MZ-Azine (3
parts by volume) was fed into a twin screw extruder. Epon.TM. 828
epoxy resin (20 parts by volume) was introduced through an
injection port.
Example 10
[0186] This example describes the preparation of Sealant Layer C.
The preparation for Sealant Layer B was repeated except that an
additional 1 part by volume Aerosil.TM. R972 silica was
incorporated into the powder mixture that was fed into the
extruder.
Example 11
[0187] This example describes the preparation of Sealant Layer D.
Dynapol.TM. S1359 (59 parts), 15 parts Epoxy Resin A, 7 parts
dicyandiamide, and 3 parts Curezol.TM. 2MZ-Azine was fed into a
twin screw extruder. 15 parts Epon.TM. 828 was introduced through
an injection port. The resulting extruded Sealant Layer D was
calendered to 1.75 mm thickness and wound onto a roll using a
Melinex.TM. 054 polyester film as a carrier.
Example 12
[0188] This example describes the preparation of Sealant Layer E.
Sealant Layer E was prepared by mixing together 90 parts
Dynapol.TM. S1402, 10 parts Epon.TM. 1001, 1 part Unilin.TM. 700
wax, and 0.5 parts of FX-512 (triarylsulfonium salt
photoinitiator). This mixture was heated on a hot plate until
homogeneous and then pressed into a layer between silicone treated
polyester liners. The film was allowed to cool to room temperature
and recrystallize.
Example 13
[0189] This example describes the preparation of Sealant Layer F.
Sealant Layer F was prepared by mixing together 80 grams
Dynapol.TM. S 1402, 20 grams Epon.TM. 1001, 1 gram Unilin.TM. 700
wax, and 0.5 grams FX-512. This mixture was heated on a hot plate
until homogeneous and then pressed into a layer between silicone
treated polyester liners. The film was allowed to cool to room
temperature and recrystallize.
Example 14
[0190] This example describes the preparation of Sealant Layer G.
Sealant Layer G was prepared by mixing together 70 parts
Dynapol.TM. S1402, 30 parts Epon.TM. 1001, 1 part Unilin.TM. 700
wax, and 0.5 parts of FX-512. This mixture was heated on a hot
plate until homogeneous and then pressed into a layer between
silicone treated polyester liners. The film was allowed to cool to
room temperature and recrystallize.
Example 15
[0191] This example describes the preparation of Sealant Layer H.
Sealant Layer H was prepared by mixing together 70 parts
Dynapol.TM. S1402, 30 parts Epoxy Resin A, 1 part Unilin.TM. 700
wax, and 0.5 parts of FX-512. This mixture was heated on a hot
plate until homogeneous and then pressed into a layer between
silicone treated polyester liners. The film was allowed to cool to
room temperature and recrystallize.
Example 16
[0192] This example describes the preparation of Sealant Layer I.
Sealant Layer I was prepared by mixing together 70 parts Polyester
A, 30 parts Epon.TM. 1001, 1 part Unilin.TM. 700 wax, and 0.5 parts
of FX-512. This mixture was heated on a hot plate until homogeneous
and then pressed into a layer between silicone treated polyester
liners. The film was allowed to cool to room temperature and
recrystallize.
Example 17
[0193] This example describes the preparation of Sealant Layer J.
Sealant Layer J was prepared by mixing together 70 parts
Dynapol.TM. S1402, 30 parts Epoxy Resin A, 1 part Unilin.TM. 700
wax, and 0.1 parts of FX-512. This mixture was heated on a hot
plate until homogeneous and then pressed into a layer between
silicone treated polyester liners. The film was allowed to cool to
room temperature and recrystallize.
Example 18
[0194] This example describes the preparation of Sealant Layer K.
Sealant Layer K was prepared by mixing together 70 parts
Dynapol.TM. S1402, 30 parts Epoxy Resin A, 1 part Unilin.TM. 700
wax, and 0.3 parts of FX-512. This mixture was heated on a hot
plate until homogeneous and then pressed into a layer between
silicone treated polyester liners. The film was allowed to cool to
room temperature and recrystallize.
Example 19
[0195] This example describes the preparation of Sealant Layer L.
Polyester A was heated to 177.degree. C., then pressed into a layer
between silicone coated polyester release liners.
Example 20
[0196] This example describes the preparation of Sealant Layer M.
Polyester A (100 parts) was heated to 177.degree. C. and mixed by
hand with 5 parts Cab-O-Sil.TM. M5 silica. The sample was pressed
into a layer between silicone coated polyester release liners.
Example 21
[0197] This example describes the preparation of Sealant Layer N.
The following formulation was extruded using a Berstorff twin screw
extruder fitted with two feeders and a liquid injection port.
Cab-O-Sil.TM. M5 fumed silica was added through one feeder. The
other feeder was used to feed the polyester pellets, wax and solid
epoxy. The liquid injection port was used to feed the liquid epoxy
resin, polyether triol, photocatalyst and sensitizer. The following
formulation was used: 50 parts Polyester A, 20 parts Epon.TM. 1001,
12.5 parts Epon.TM. 828, 7.5 parts Voranol.TM. 230-238 polyether
triol, 1 part Unilin.TM. 700, 2 parts SarCat.TM. CD 1012
photocatalyst, 0.5 parts 1,3-diphenylisobenzofiran, 7 parts
Cab-O-Sil.TM. M5.
[0198] The extrudate was fed into a calender nip between two
process liners and calendered to a thickness of 1.5 mm. The top
side liner was a polycoated silicone paper liner, and the bottom
side liner was a green-colored polyethylene liner. Using the liners
resulted in a very uniform coating of the sealant between the two
liners and also assisted in protecting the sealant from ambient
light. The paper liner was stripped off, leaving the green
polyethylene liner in place. The use of Polyester A resin
significantly simplified the extrusion operation since the fast
recrystallization process enhanced the windability and resulted in
a tack-free sealant.
Example 22
[0199] This example describes the preparation of Sealant Layer O.
Polyester A (57 parts), 15 parts Epon.TM. 1001F, 12.5 parts
Epon.TM. 828, 7.5 parts Voranol.TM. 230-238, 1 part Unilin.TM. 700,
5 parts Santicizer.TM. 278, 2 parts diphenyliodonium
hexafluorophosphate, 0.005 parts 1,3-diphenylisobenzofiuran, and 3
parts Aerosil.TM. R972 silica were heated to 127.degree. C. and
melt mixed by hand. Samples were pressed into layers between
silicone coated polyester release liners.
Example 23
[0200] This example describes the preparation of Sealant Layer P.
Sealant Layer P was prepared by melt mixing 10 parts Dynapol.TM.
S1402, 10 parts Epon.TM. 1001, and 4 parts Benzoflex.TM. S-404
plasticizer. This sample had a much longer recrystallization time
than samples not containing the plasticizer. Samples were pressed
into layers between silicone coated polyester release liners.
Example 24
[0201] This example describes the preparation of Sealant Layers Q
through V. Table 1 gives the parts by weight of ingredients used to
prepare Sealant Layers Q through V. The components were melt mixed
and pressed into layers between silicone coated polyester release
liners.
1TABLE 1 Seal- Seal- Seal- Sealant Sealant Sealant ant ant ant
Layer Layer Layer Layer Layer Layer Ingredient Q R S T U V
Polyester A 45 45 45 0 0 0 Dynapol .TM. S1402 0 0 0 45 45 45
Synthetic Resin SK 15 0 0 0 0 0 Synthetic Resin AP 0 15 0 15 0 0
Synthetic Resin CA 0 0 15 0 15 0 Synthetic Resin LTH 0 0 0 0 0
15
[0202] Overlap shear adhesion panels were prepared by placing a
12.7 mm by 25.4 mm piece of each sealant layer between an anodized
aluminum coupon and a DCT 5000 metal coupon as outlined above in
the Overlap Shear test method, and heating on a hot plate to allow
the sealant layer to soften. Overlap bonds were made while the
sealant was still molten such that an approx. 25 mm by 25 mm
sealant layer area was realized. These samples were allowed to cool
for 24 hours prior to testing. Table 2 shows overlap shear test
results.
2TABLE 2 Sealant Sealant Sealant Sealant Sealant Sealant Ingredient
Layer Q Layer R Layer S Layer T Layer U Layer V Overlap 4.62 4.04
4.75 2.10 2.37 3.43 Shear Adhesion (MPa) Failure Mode AA AA AA AA
AA AA "AA" means adhesive failure at the DCT 5000/sealant layer
interface.
Example 25
[0203] This example describes the preparation of Sealant Layer W.
Sealant Layer W was prepared by melt mixing by hand 45 parts
Dynapol.TM. S 1402, 30 parts Dynacoll.TM. 7130, 20 parts Epon.TM.
828, 5 parts Voranol.TM. 230-238, 1 part SarCat.TM. CD 1012, 0.005
part 1,3-diphenylisobenzofuran, and coating the mixture onto a
silicone coated polyester film at 1.0 mm thickness.
Example 26
[0204] This example describes the preparation of Sealant Layers X
through Z. Table 3 shows the parts by weight of the ingredients
used to prepare Sealant Layers X through Z. The components were
melt mixed by hand and coated at 1 mm thickness between silicone
coated polyester liners.
3TABLE 3 Sealant Layer Sealant Layer Sealant Layer Ingredient X Y Z
Polyester A 12 12 12 Epon .TM. 828 4 4 4 Synthetic Resin CA 4 4 4
Metallocene 0.15 0.15 0.15 Catalyst A Octaflow .TM. ST 70 0.5 0 0
Oxymelt .TM. A-1 0 1 0 Isocryl .TM. EP550 0 0 2
Example 27
[0205] This example describes the preparation of Sealant Layer AA.
Sealant Layer AA was prepared by melt mixing by hand 12 parts
Vitel.TM. 5833B polyester, 8 parts Epon.TM. 828, and 0.2 part
Metallocene Catalyst A. The mixture was coated at 1.0 mm thickness
between silicone coated polyester liners. The layer was laminated
to anodized aluminum foil, heated in an oven to 125.degree. C.,
removed from the oven and immediately photolyzed with a Fusion
Systems Processor (Lamp Model i300MB, conveyor model LC-6) at 24.4
meters/minute (total energy was about 103 mjoules), and laminated
to Stainguard.TM. IV and DCT 5000 panels. In both cases adhesive
failure at the paint/sealant layer interface was observed.
Example 28
[0206] This example describes the preparation of Sealant Layers AB
through AH. Table 4 shows the parts by weight of ingredients used
to prepare Sealant Layers AB through AH. To prepare the following
examples samples were melt mixed by hand to reach a homogeneous
mixture. Silica was manually well dispersed in the mixture with a
tongue depressor. Samples were cast between silicone treated
polyethylene terephthalate liners using spacers to create the
desired thickness of 1.0 mm.
4TABLE 4 Sealant Sealant Sealant Sealant Sealant Layer Layer Layer
Layer Layer Formulation AB AC AD AE AF Polyester A 16 16 16 16 20
Vitel .TM. 5833B 4 4 4 4 0 Synthetic Resin CA 8 8 8 8 8 Dynapol
.TM. 81313 4 4 4 4 4 Epon .TM. 828 6 6 6 6 6 Epon .TM. SU-8 2 2 2 2
2 Cab-O-Sil .TM. M-5 2 0 2 2 2 Silica 1,12-Dodecanedioic 0 0 3 6
1.5 Acid Metallocene Catalyst 0.2 0.2 0.2 0.2 0.2 A
[0207]
5TABLE 5 Sealant Sealant Sealant Sealant Sealant Layer Layer Layer
Layer Layer Test Results AB AC AD AE AF 45.degree. Flow Test
Results <1 mm 94 mm <1 mm <1 mm <1 mm (20 mm at
120.degree. C.)
Example 29
[0208] This example illustrates the co-dependence of core and
sealant layer thickness on gap filling effectiveness. Sealant Layer
AB was prepared at 1.0, 2.0, and 3.0 mm thicknesses as before. Core
Layer B was laminated together to prepare 2.0 and 3.0 mm thick core
layers. Three sealant thicknesses were then laminated to the three
core layer thicknesses. Tape samples were then cut to 10 mm width
by 127 mm length.
[0209] Glass coupons (5.08 cm by 12.7 cm by 0.394 cm) were primed
with a 1 wt. % solution of 3-aminopropyltrimethoxysilane in
methanol and allowed to dry at room temperature. Tape samples were
then laminated to the primed glass surface. ED 5100 (25.4 mm by 102
mm by 0.89 mm) coupons were laminated together with Bonding Layer A
(0.51 mm thickness) to make spacers of various thicknesses and
these were attached to a DCT 5002 painted panel (102 mm by 305 mm).
The first stack was 5.6 mm, the second stack was 4.0 mm, the third
stack was 2.6 mm, and the last stack was 1.8 mm. The spacing
between stacks was 10 mm. The panel was then baked for 25 minutes
at 140.degree. C. The taped glass coupons were then placed in an
oven for approximately 5 minutes at 120.degree. C. The coupons were
then exposed to one pass at 16.5 meter/minute on the Fusion Systems
Processor. The taped glass coupon was then pressed onto the stacked
panel so that the coupon spanned the gaps, and hand pressure was
applied and released, and the sample allowed to cool. The gaps were
then inspected to determine if the sealant was able to span the gap
and wet-out the painted surface.
[0210] The table below shows the results. "C" indicates that a seal
was achieved; "I" indicates an incomplete seal. As can be seen, the
core layer contributes to sealing efficiency by assisting the
sealant layer to reach into gaps that would otherwise require more
sealant.
6TABLE 6 Core Sealant Gap Depth Gap Depth Gap Depth Thickness
Thickness 2.6 mm 4.0 mm 5.6 mm 1 mm 1 mm C I I 2 mm 1 mm C I I 3 mm
1 mm C I I 1 mm 2 mm C C I 2 mm 2 mm C C I 3 mm 2 mm C C I 1 mm 3
mm C C I 2 mm 3 mm C C C 3 mm 3 mm C C C
Example 31
[0211] This examples describes a Two Layer Tape Construction A and
its use with bracket mounted windows. Bonding Layer A was laminated
to the Melinex.TM. 054 side of 1.0 mm thick Sealant Layer D. The
resulting laminate was then cut into a 25.4 mm.times.50.8 mm strip.
The release liner was then removed from the bonding layer side and
the tape applied to one side of a piece of plate glass near the
edge of the glass. It was then wrapped around the edge of the glass
and fastened to the opposite side of the glass so that the Sealant
Layer faced out. A metal U-shaped channel bracket was then slid
over the tape. There was enough resistance to maintain a snug fit.
The assembly was then placed in an oven and baked for 25 minutes at
141.degree. C. The sealant layer had filled the channel
encompassing the glass and had filled the bracket volume
sufficiently to give a look which closely resembled that for paste
adhesive systems.
[0212] The strength of the bond between the metal and the glass was
tested using the Tensile and Elongation Test after periods up to 14
days at 70.degree. C., or alternatively at 37.8.degree. C. and 100
% relative humidity, and resulted in fracture of the glass.
Delamination or adhesive failure at either substrate was not
observed.
Example 31
[0213] This examples describes the preparation of a Two Layer Tape
Construction B. Sealant Layer W was laminated to Core Layer D which
had been primed with Primer Composition A using a #5 Meyer (wire
wound) rod. The primer was allowed to dry for about 5 minutes prior
to laminating it to the core layer. The resulting laminate was then
slit into 12.7 mm wide strips.
[0214] The frit surface of a piece of a 1985 Buick Somerset quarter
window glass, was primed with a solution of Primer Composition A
with 2 wt. % 3-aminopropyltrimethoxysilane added thereto. This
solution was then brushed onto the frit bonding surface of the
glass and allowed to air dry at room temperature. The foam core
layer side of the tape construction was then laminated to the glass
using a scarf joint to butt the ends of the tape together
encircling the circumference of the part.
[0215] The resultant assembly was then packaged by using an
overhanging liner composed of 76.2 mm wide labeling tape which had
a liner layer of green polyethylene laminated to it. The tape was
applied over the taped surface by having the liner serve as a light
protector for the sealant and overhanging the tacky labeling tape
so that it bonded along the surface edge of the tape. A quartz IR
lamp was used to heat the surface of the tape. It took
approximately 2 minutes in order for this light system to heat the
tape to 80.degree. C. Next the taped glass assembly was exposed to
a super diazo blue lamp (Black Ray Lamp Model No. XX-15L, from UVP
Inc., San Gabriel, California, equipped with two bulbs, Model TLD
15W/03 from Philips B.V., The Netherlands) for 25 seconds ( total
energy was approx. 137 mjoules), and then installed in a painted
metal cut-out. Good flow occurred. The sealant was able to flow
through the weld spot burn holes and mushroom on the opposite side
forming a good seal.
Example 32
[0216] These examples describe the preparation of Two Layer Tape
Constructions C through E. Sealant Layers X through Z were
laminated to Core Layer C (primed with Primer Composition A), and
the core layers were then laminated to anodized aluminum foil. The
sealant layer was then exposed to UV light from a Fusion Systems
Processor (total energy was approx. 137 mjoules) and applied to DCT
5000 painted metal coupons at room temperature and refrigerated
panels. Samples were aged overnight and pulled apart by hand
followed by scraping with a spatula to try to force an adhesive
failure.
7TABLE 7 2 Layer Tape Sealant Re- Re- Room Room Construc- Layer
frigerated frigerated Temperature Temperature tion Used First Pull
Scraping First Pull Scraping C X AD AD AD AD D Y FS Coh FS Coh E Z
FS Coh/AD FS Coh/AD In Table 7, "FS" means that the foam core layer
split (core layer cohesive failure); "AD" means adhesive failure at
the sealant layer/paint layer interface; "Coh" means cohesive
failure of the sealant layer.
Example 33
[0217] This example describes the preparation of Two Layer Tape
Construction F. As a comparative example, Hydrosil.TM. 2627 glass
primer was applied to a 50.7 mm.times.100.1 mm piece of glass. A
6.3 mm diameter bead of Auto Glass Urethane Windshield Adhesive No.
08693 was applied to the glass and the assembly was laminated to a
DCT 5002 painted metal coupon.
[0218] According to the invention, Core Layer E was applied to a
separate piece of glass primed as above. A 6.3 mm bead of Auto
Glass Urethane Windshield Adhesive No. 08693 was then applied to
the foam core layer, and the assembly applied to the painted metal
coupon as before.
[0219] In both cases, sufficient pressure was applied to each
sample to squeeze the urethane out against the metal panel. After 1
week the samples were inspected, and it was apparent that each
construction was firmly bonded to the panel; however, in the case
of the sample with Core Layer E, the glass had an increased ability
to move relative to the metal coupon without bond failure.
Example 34
[0220] This example describes the preparation of Three Layer Tape
Construction A having a polyester tie layer and its use to bond
glass to metal. Core Layer A was laminated to the polyester side of
Sealant Layer D. On the opposite face of core layer A, a 0.25 mm
thick layer of bonding layer A was laminated. The laminate was cut
into a strip 19 mm wide and 100 mm long, and the bonding layer was
laminated to 4 mm thick plate glass. A 25.4 mm.times.100.2 mm
E-coated metal coupon was laid over the top of the sealant layer.
Spring clips were used to secure the ends of the E-coated coupon to
the glass plate creating a normal force that was meant to simulate
the weight of a windshield. A 25.4 mm.times.50.8 mm anodized
aluminum coupon was laid over the opposite edge of the sealant
layer and the sample placed in an oven for 25 minutes at
177.degree. C. Upon removal from the oven, Bonding Layer A had
changed color indicating that the tape had achieved a thermoset
state. Flow of the sealant layer and formation of a bond to the
coupon was observed in both cases.
[0221] When the anodized panel was deformed a significant amount of
acrylic foam core deformation occurred in the direction
perpendicular to the coupon, and the assembly remained intact.
Example 35
[0222] This example describes the preparation of Three Layer Tape
Construction B having a polyester tie layer and its use with
bracket mounted windows. A 30 mil thick layer of Bonding Layer A
was hand laminated to Core Layer B. Sealant Layer F was laminated
onto the opposite face of the Core Layer B.
[0223] A sample strip 25.4 mm by 76.2 mm was cut from the composite
laminate and the bonding layer was laminated to a 50.8 mm.times.127
mm piece of flat plate glass. This assembly was then placed in a
forced air convection oven at 140.degree. C. for 20 minutes with
the tape facing up. After baking it was observed that the bonding
layer had changed appearance and was now a mottled gray in
appearance and the sealant had softened/melted and was translucent
in appearance. The sealing layer did not run out and over the edge
of the tape which would have resulted in encapsulation of the
bonding and foam layers of the tape. Upon cooling the sealant
resolidified to a tack free state.
[0224] The assembly was then aged overnight and the next day the
sample was exposed to 5 minutes of low intensity UV radiation at a
distance of approximately 25.4 mm. After the exposure, a heat gun
was used to heat the tape. During the heating the sealant mass was
observed to go translucent and glossy in appearance which indicates
softening of the sealer mass. A 25.4 mm.times.100.2 mm painted (DCT
5002) piece of steel was bent into an inverted `U` shape with a
channel depth of approximately 3 mm. This was pressed, with hand
pressure, onto the softened sealer mass along its length to try to
simulate the sealer's ability fill gaps which are of greater depth
than the thickness of the sealer layer itself. Visually, one could
see that the sealant layer had effectively flowed toward the
channel cavity and was able to make contact with the deepest part
of the metal panel.
[0225] During the flow and bonding process, the sealant was
observed to wet-out the entire face of the painted surface and then
when hand pressure was released, the sealer necked in from the edge
creating a slight cavity. To test whether this cavity was sealed,
water was poured into the cavity. It was determined that an
effective seal had been achieved by the fact that the water was
retained in the cavity.
Example 36
[0226] This example describes the preparation of Three Layer Tape
Construction C having a polyester tie layer and its use with
bracket mounted windows. Tape Construction C was prepared by
laminating Core Layer B to Sealant Layer E. On the opposite face of
Core Layer B was laminated Bonding Layer A. The laminate was cut
into a strip 12.7 mm.times.25.4 mm, and the bonding layer was
laminated to 4 mm thick plate glass. The sealant layer of the
laminate was then exposed to UV radiation for 5 minutes using the
Sylvania fluorescent black light bulbs described in conjunction
with Example 2 at an approximate distance of 10 cm. The laminate
was then placed onto a DCT 5002 painted metal panel so that the
sealant layer was on top of and in contact with the panel. The
sample was placed in an oven for 20 minutes at 141.degree. C.
[0227] The strength of the bond between the metal and the glass was
tested using the Tensile and Elongation Test after periods up to 20
days at 70.degree. C. or, alternatively, at 37.8.degree. C. and
100% relative humidity, and resulted in fracture of the core layer.
Delamination or adhesive failure at either substrate was not
observed.
Example 37
[0228] This example illustrates Three Layer Tape Construction D
having a polyester tie layer and its use with bracket mounted
windows. Tape Construction D was prepared by laminating Core Layer
B to Sealant Layer F. On the opposite face of Core Layer B was
laminated Bonding Layer A. The laminate was cut into a strip 12.7
mm.times.25.4 mm, and the bonding layer was laminated to 4 mm thick
plate glass. The sealant layer of the laminate was then exposed to
UV radiation for 5 minutes using the Sylvania fluorescent black
light bulbs described in conjunction with Example 2 at an
approximate distance of 10 cm. The laminate was then placed onto a
DCT 5002 metal panel so that the sealant layer was on top of and in
contact with the panel. The sample was placed in an oven for 20
minutes at 141.degree. C.
[0229] The strength of bond between the metal and the glass was
tested using the Tensile and Elongation Test after periods up to 20
days at 70.degree. C or alternatively at 37.8.degree. C. and 100%
relative humidity, and resulted in fracture of the core layer.
Delamination or adhesive failure at either substrate was not
observed.
Example 38
[0230] This example describes the preparation of Three Layer Tape
Construction E having a polyester tie layer and its use with
bracket mounted windows. Tape Construction E was prepared by
laminating Core Layer C to Sealant Layer G. On the opposite face of
Core Layer C was laminated Bonding Layer A. The laminate was cut
into a strip 12.7 mm.times.25.4 mm, and the bonding layer was
laminated to 4 mm thick plate glass. The sealant layer of the
laminate was then exposed to UV radiation for 5 minutes using the
Sylvania fluorescent black light bulbs described in conjunction
with Example 2 at an approximate distance of 10 cm. The laminate
was then placed onto a DCT 5002 metal panel so that the sealant
layer was on top of and in contact with the panel. The sample was
placed in an oven for 20 minutes at 141.degree. C.
[0231] The strength of bond between the metal and the glass was
tested using the Tensile and Elongation Test after periods up to 20
days at 70.degree. C. or alternatively at 37.8.degree. C. and 100%
relative humidity, and resulted in fracture of the core layer.
Delamination or adhesive failure at either substrate was not
observed.
Example 39
[0232] This example describes the preparation of Three Layer Tape
Construction F having a polyester tie layer and its use with
bracket mounted windows. Tape Construction F was prepared by
laminating Core Layer B to Sealant Layer H. On the opposite face of
Core Layer B was laminated Bonding Layer A. The laminate was cut
into a strip 12.7 mm by 25.4 mm, and the bonding layer was
laminated to 4 mm thick plate glass. The sealant layer of the
laminate was then exposed to UV radiation for 5 minutes using the
Sylvania fluorescent black light bulbs described in conjunction
with Example 2 at an approximate distance of 10 cm. The laminate
was then placed onto a DCT 5002 metal panel so that the sealant
layer was on top of and in contact with the panel. The sample was
placed in an oven for 20 minutes at 141.degree. C.
[0233] The strength of bond between the metal and the glass was
tested using the Tensile and Elongation Test after periods up to 20
days at 70.degree. C. or alternatively at 37.8.degree. C. and 100%
relative humidity, and resulted in fracture of the core layer.
Delamination or adhesive failure at either substrate was not
observed.
Example 40
[0234] This example describes the preparation of Three Layer Tape
Construction G having a polyester tie layer and its use with
bracket mounted windows. Tape Construction G was prepared by
laminating Core Layer B to Sealant Layer I. On the opposite face of
Core Layer B was laminated Bonding Layer A. The laminate was cut
into a strip 12.7 mm by 25.4 mm, and the bonding layer was
laminated to 4 mm thick plate glass. The sealant layer of the
laminate was then exposed to UV radiation for 5 minutes using the
Sylvania fluorescent black light bulbs described in conjunction
with Example 2 at an approximate distance of 10 cm. The laminate
was then placed onto a DCT 5002 metal panel so that the sealant
layer was on top of and in contact with the panel. The sample was
placed in an oven for 20 minutes at 141.degree. C.
[0235] The strength of bond between the metal and the glass was
tested using the Tensile and Elongation Test after periods up to 20
days at 70.degree. C. or, alternatively, at 37.8.degree. C. and
100% relative humidity, and resulted in fracture of the core layer.
Delamination or adhesive failure at either substrate was not
observed.
Example 41
[0236] This example describes the preparation of Three Layer Tape
Construction having a polyester tie layer and its use with bracket
mounted windows. Tape Construction H was prepared by laminating
Core Layer B to Sealant Layer J. On the opposite face of Core Layer
B was laminated Bonding Layer A. The laminate was cut into a strip
12.7 mm by 25.4 mm, and the bonding layer was laminated to 4 mm
thick plate glass. The sealant layer of the laminate was then
exposed to UV radiation for 5 minutes using the Sylvania
fluorescent black light bulbs described in conjunction with Example
2 at an approximate distance of 10 cm. The laminate was then placed
onto a DCT 5002 painted metal panel so that the sealant layer was
on top of and in contact with the panel. The sample was placed in
an oven for 20 minutes at 141.degree. C. The strength of bond
between the metal and the glass was tested using the Tensile and
Elongation Test after periods up to 20 days at 70.degree. C. or,
alternatively, at 37.8.degree. C. and 100% relative humidity, and
resulted in fracture of the core layer. Delamination or adhesive
failure at either substrate was not observed.
Example 42
[0237] This example describes the preparation of Three Layer Tape
Construction I and its use to bond glass to metal. Tape
Construction I was prepared by laminating Core Layer B to Sealant
Layer K. On the opposite face of Core Layer B was laminated Bonding
Layer A. The laminate was cut into a strip 12.7 mm by 25.4 mm, and
the bonding layer was laminated to 4 mm thick plate glass. The
sealant layer of the laminate was then exposed to UV radiation for
5 minutes using the Sylvania fluorescent black light bulbs
described in conjunction with Example 2 at an approximate distance
of 10 cm. The laminate was then placed onto a DCT 5002 metal panel
so that the sealant layer was on top of and in contact with the
panel. The sample was placed in an oven for 20 minutes at
141.degree. C.
[0238] The strength of bond between the metal and the glass was
tested using the Tensile and Elongation Test after periods up to 20
days at 70.degree. C. or, alternatively, at 37.8.degree. C. and
100% relative humidity, and resulted in fracture of the core layer.
Delamination or adhesive failure at either substrate was not
observed.
Example 43
[0239] This example describes the preparation of Three Layer Tape
Construction J. Sealant Layer L was laminated to itself to a
thickness of 4 plies to achieve a final thickness of approximately
4.0 mm. The 4 ply laminated samples were then further laminated to
a 1.0 mm thick piece of Core Layer B and then Bonding Layer A was
laminated to the opposite face of the acrylic foam. Multiple
samples were then cut 25.4 mm by 12.7 mm and horizontally laminated
to a piece of plate glass at one edge. The glass was then racked in
a vertical fashion with the tapes on the upper edge and placed in
an oven set at 141.degree. C. for 25 minutes. Upon removal from the
oven, the entire sealant layer had flowed.
Example 44
[0240] This example describes the preparation of Three Layer Tape
Construction K. Sealant Layer M was laminated to itself to a
thickness of 4 plies to achieve a final thickness of approximately
4.0 mm. The 4 ply laminated samples were then further laminated to
a 1.0 mm thick piece of Core Layer B and then Bonding Layer A was
laminated to the opposite face of the acrylic foam. Multiple
samples were then cut 25.4 mm by 12.7 mm and horizontally laminated
to a piece of plate glass at one edge. The glass was then racked in
a vertical fashion with the tape on the upper edge and placed in an
oven set at 141.degree. C. for 25 minutes. Upon removal from the
oven, the sealant layer had flowed approximately 25.4 mm down the
face of the glass panel.
Example 45
[0241] This example describes the preparation of Three Layer Tape
Construction L. Sealant Layer N was laminated to itself to a
thickness of 4 plies to achieve a final thickness of approximately
4.0 mm. The 4 ply laminated samples were then further laminated to
a 1.0 mm thick piece of Core Layer B and then Bonding Layer A was
laminated to the opposite face of the acrylic foam. Multiple
samples were then cut 25.4 mm by 12.7 mm and horizontally laminated
to a piece of plate glass at one edge. The glass was then racked in
a vertical fashion with the tape on the upper edge and placed in an
oven set at 141.degree. C. for 25 minutes. Upon removal from the
oven, no flow of the sealant layer was observed and the sealant
still had square edges. After cooling the material was then
reheated for 5 minutes at 141.degree. C., taken from the oven and a
25.4 mm by 100.2 mm E-coated metal coupon with a 0.63 mm hole
cutout was pressed against the 10% silica containing sealant. The
sealant was observed to easily flow out and around the coupon, into
the hole and swelled on the back side to physically lock the coupon
to the sealant. The sealant cooled quickly and recrystallized to
form a strong bond/seal.
Example 46
[0242] This example describes the preparation of Three Layer Tape
Construction M. Bonding Layer A was laminated to a 3.0 mm thickness
Core Layer E laminated in turn to a 1.5 mm thick Sealant Layer
O.
Example 47
[0243] This example describes a glass window installation according
to the invention. Glass and a metal cut-out were obtained from a
1985 Buick Somerset quarter window (believed to be encapsulated
with polyvinyl chloride (PVC)). Both surfaces were cleaned and the
metal repainted prior to use with a conventional automotive repair
paint. Three Layer Tape Construction M was converted into strips
which were approximately 12.7 mm wide. The bonding layer of the
tape was bonded to the perimeter of the glass at room temperature
conditions, followed by heating with a quartz infrared lamp to
activate the bonding layer. During the process the PVC encapsulant
began to smoke. The sample was allowed to cool and the tape was
reheated by exposing the sealant face to the infrared radiation.
After it was softened, the laminated construction was exposed to 10
seconds of light using the super diazo blue lamp described in
conjunction with Example 31; the exposure was (approximately 110
mjoules/cm.sup.2). The sample was then quickly installed into the
metal cutout by applying uniform pressure to the face of the
glass.
Example 48
[0244] This example describes another glass window installation
according to the invention. Similar to Example 47, the glass was
preheated with infrared radiation to approx. 82.2.degree. C. Three
Layer Tape Construction M was easily applied to the perimeter of
the glass. The ends were lapped side by side for approximately 76.2
mm to effect a seal. Additional infrared heat was applied to the
back side (through the glass). After approximately 20 minutes the
sample was allowed to cool. The sealant layer was reheated with
infrared, then exposed to light using the super diazo blue lamp
described in conjunction with Example 31 and installed into the
metal cut out effecting a good seal.
Example 49
[0245] This example describes metal to glass seating using a 3
Layer Tape Construction. Bonding Layer A was laminated to one
surface of Core Layer F, the sample was slit to a width of 12.7 mm,
and the strip was laminated to a glass substrate and placed in an
oven for 25 minutes at 140.degree. C. After removing the sample
from the oven and allowing it to cool to room temperature, a 10 mm
diameter bead of Auto Glass Urethane Windshield Adhesive No. 08693
was applied to Core Layer F and the resulting assembly was
laminated to a DCT 5002 metal panel with sufficient pressure to
squeeze the sealant out against the surface. The film was allowed
to cure overnight under ambient conditions, thereby creating a good
seal.
Example 50
[0246] This example describes metal to glass sealing using a 3
Layer Tape Construction. The procedure of Example 49 was repeated
except that Sealant Layer AB was used instead of the urethane
paste. Thus, Sealant Layer AB was laminated on the surface of the
Core Layer F and the assembly was heated to 120.degree. C. for
approximately 5 minutes. The sample was then exposed to one pass at
16.5 meter/minute using the Fusion Systems Processor. The sample
was then placed on a DCT 5002 metal panel and sufficient pressure
applied to insure good wet-out.
Example 51
[0247] This example describes metal to glass sealing using a 3
Layer Tape Construction. In this example, Bonding Layer A was
applied in the form of a 25.4 mm wide tape around the perimeter of
a 102 mm by 203 mm piece of glass. The taped glass was cured for 25
minutes at 140.degree. C.
[0248] Sealant Layer AF was laminated to a two ply laminate of Core
Layer B (2 mm thickness) and slit to 12.7 mm width. This strip was
then laminated to the cured Bonding Layer A. A tenacious bond was
observed between the cured bonding layer and the core layer. A
scarf joint was used to attach the two ends after encircling the
perimeter of the glass. This assembly was then heated to
120.degree. C. for approximately 5 minutes and exposed at 16.5
meter/minute using the Fusion Systems Processor. The assembly was
then laminated to a DCT 5002 metal panel to produce a good
seal.
Example 52
[0249] This example describes metal to glass sealing using a 3
Layer Tape Construction. In this example, Bonding Layer A was
laminated to a two ply laminate of Core Layer B (2 mm thickness)
and slit to form a 12.7 mm width tape. The Bonding Layer A side of
the tape was laminated to the perimeter of an isopropanol-cleaned,
102 mm by 203 mm piece of glass. A scarf joint was used to butt the
two ends together and the sample was baked for 25 minutes at
140.degree. C. The sample was allowed to cool. After cooling,
Sealant Layer AB (12.7 mm width) was laminated to the core layer
and the two ends were butted together. This assembly was then
heated for approximately 5 minutes at 120.degree. C. and exposed at
16.5 meter/minute using the Fusion Systems Processor. The assembly
was then laminated to a DCT 5002 metal panel to create a good
seal.
[0250] Other embodiments are within the following claims. While the
invention has been described with reference to the particular
embodiments and drawings set forth above, the spirit of the
invention is not so limited and is defined by the appended
claims.
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