U.S. patent application number 11/037758 was filed with the patent office on 2006-12-28 for methods for embossing and embossed articles formed thereby.
Invention is credited to James Anthony Cella, Thomas Bert Gorczyca, John Bradford Reitz.
Application Number | 20060293421 11/037758 |
Document ID | / |
Family ID | 23093738 |
Filed Date | 2006-12-28 |
United States Patent
Application |
20060293421 |
Kind Code |
A1 |
Reitz; John Bradford ; et
al. |
December 28, 2006 |
Methods for embossing and embossed articles formed thereby
Abstract
A method for manufacturing an embossed surface including a
polymer composition having reactive moieties and a first glass
transition temperature T.sub.g1. The method includes embossing the
surface a temperature T.sub.emb; and raising the first glass
transition temperature T.sub.g1 of the embossed polymeric surface
to a second glass transition temperature T.sub.g2 such that
T.sub.g2>T.sub.emb. In another embodiment, a method for
improving the release of a polymeric surface from an embossing tool
includes incorporating one or more of fluorine atoms, silicon
atoms, or siloxane segments into the backbone of polymer. The
methods are particular suited for direct patterning of
photoresists, fabrication of interdigitated electrodes, and
fabrication of data storage media.
Inventors: |
Reitz; John Bradford;
(US) ; Gorczyca; Thomas Bert; (US) ; Cella;
James Anthony; (US) |
Correspondence
Address: |
CANTOR COLBURN, LLP
55 GRIFFIN ROAD SOUTH
BLOOMFIELD
CT
06002
US
|
Family ID: |
23093738 |
Appl. No.: |
11/037758 |
Filed: |
January 18, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10063407 |
Apr 19, 2002 |
6977057 |
|
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11037758 |
Jan 18, 2005 |
|
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60285323 |
Apr 19, 2001 |
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Current U.S.
Class: |
524/104 ;
524/105; G9B/5.299; G9B/7.196 |
Current CPC
Class: |
C08G 73/1071 20130101;
G11B 7/241 20130101; B29C 59/005 20130101; C08G 73/1042 20130101;
G11B 7/263 20130101; H01B 3/306 20130101; G11B 5/74 20130101; C08G
73/1064 20130101; G11B 11/10582 20130101; C08G 73/1039 20130101;
C08G 73/106 20130101; C08G 73/1067 20130101; C08G 73/10 20130101;
G11B 5/8404 20130101 |
Class at
Publication: |
524/104 ;
524/105 |
International
Class: |
C08K 5/34 20060101
C08K005/34; C08K 5/3445 20060101 C08K005/3445 |
Claims
1. An article comprising a surface, wherein the surface comprises a
polymer composition having a first glass transition temperature
(T.sub.g1), and wherein the article is formed by: embossing the
surface at temperature T.sub.emb; and altering the T.sub.g1 of the
surface polymer composition to provide a second glass transition
temperature (T.sub.g2), wherein the altering is during embossing,
after embossing, or both during and after embossing.
2. The article of claim 1, wherein the polymer composition
comprises a thermoplastic polymer, a thermoset polymer, a blend
comprisig a thermoplastic polymer, a blend comprising a thermoset
polymer, or a blend comprising a thermoplastic polymer and a
thermoset polymer.
3. The article of claim 2, wherein the polymer is a thermoplastic
selected from the group consisting of polyvinyl chloride,
polyolefins, polyethylene, chlorinated polyethylene, polypropylene,
polyesters, polyethylene terephthalate, polybutylene terephthalate,
polycyclohexylmethylene terephthalate, polyamides, polysulfones,
hydrogenated polysulfones, polyimides, polyether imides, polyether
sulfones, polyphenylene sulfides, polyether ketones, polyether
ether ketones, ABS resins, polystyrenes, hydrogenated polystyrenes,
syndiotactic and atactic polystyrenes, polycyclohexyl ethylene,
styrene-co-acrylonitrile, styrene-co-maleic anhydride,
polybutadiene, polyacrylates, polymethylmethacrylate, methyl
methacrylate-polyimide copolymers, polyacrylonitrile, polyacetals,
polycarbonates, polyphenylene ethers, ethylene-vinyl acetate
copolymers, polyvinyl acetate, liquid crystal polymers,
ethylene-tetrafluoroethylene copolymer, aromatic polyesters,
polyvinyl fluoride, polyvinylidene fluoride, polyvinylidene
chloride, polytetrafluoroethylene, and combinations comprising at
least one of the foregoing thermoplastics.
4. The article of claim 2, wherein the polymer is a thermoplastic
blend selected from the group consisting of
acrylonitrile-butadiene-styrene/nylon,
polycarbonate/acrylonitrile-butadiene-styrene, acrylonitrile
butadiene styrene/polyvinyl chloride, polyphenylene
ether/polystyrene, polyphenylene ether/nylon,
polysulfone/acrylonitrile-butadiene-styrene,
polycarbonate/thermoplastic urethane, polycarbonate/polyethylene
terephthalate, polycarbonate/polybutylene terephthalate,
thermoplastic elastomer alloys, nylon/elastomers,
polyester/elastomers, polyethylene terephthalate/polybutylene
terephthalate, acetal/elastomer, styrene-maleic
anhydride/acrylonitrile-butadiene-styrene, polyether
etherketone/polyethersulfone, polyimide/polysiloxane,
polyetherimide/polysiloxane, polyethylene/nylon,
polyethylene/polyacetal, and combinations comprising at least one
of the foregoing blends of thermoplastic polymers.
5. The article of claim 2, wherein the polymer is a thermoset
selected from the group consisting of epoxys, phenolics, alkyds,
polyesters, polyurethanes, silicone polymers, mineral filled
silicones, bis-maleimides, cyanate esters, vinyl, benzocyclobutene
polymers, and combinations comprising at least one of the foregoing
thermosetting polymers.
6. The article of claim 1, wherein the polymer is selected from the
group consisting of polyimides, polyetherimides, copolymers of
polyimides, copolymers of polyetherimides, and blends comprising at
least one of the foregoing polymers.
7. The article of claim 6, wherein the polymer comprises reactive
moieties selected from the group consisting of vinyl substituted
aromatic monoamines, polyfunctional alkenyl aromatic monomers,
acryloyl monomers, sulfides, toluidines, ethynyl groups, ethyl
groups, ethenyl groups, epoxies, fluoroolefins, alkoxysilanes, and
combinations comprising at least one of the foregoing reactive
moieties.
8. The article of claim 6, wherein T.sub.g2 is greater than
T.sub.emb, wherein T.sub.g2 is greater than T.sub.g1, or wherein
T.sub.g2 is greater than T.sub.emb and T.sub.g1.
9. The article of claim 6, wherein the polymer comprises a reactive
plasticizer having the structural formula A-R-A wherein A is a
reactive functionality selected from the group consisting of vinyl
substituted aromatic monoamines, polyfunctional alkenyl aromatic
monomers, acryloyl monomers, sulfides, toluidines, ethynyl groups,
ethyl groups, ethenyl groups, epoxies, fluoroolefins,
alkoxysilanes, and combinations comprising at least one of the
reactive functionalities and R is a monomeric or oligomeric
polyimide repeat unit shown in the formula (XVIII) ##STR20##
wherein Y is --O-- or a group of the formula --O- Z- O-- wherein
the divalent bonds of the --O-- or the --O- Z- O-- group are in the
3,3', 3,4', 4,3', or the 4,4' positions, and wherein Z comprises
divalent radicals of formula (III) ##STR21## wherein n is an
integer from 0 to about 5 and Ar is an aromatic group comprising
reactive diamines.
10. The article of claim 6, wherein the polymer comprises a
reactive plasticizer selected from the group having the structural
formula XIXa, XIXb, XIXc, ##STR22## or combinations comprising at
least one of XIXa, XIXb, XIXc, wherein R is an aromatic moiety
having about 36 to about 60 carbon atoms.
11. The article of claim 6, wherein the polymer comprises about 0.1
to about 30 wt. % reactive moieties, based on the total weight of
the polymer.
12. An embossed polymer surface formed by a process comprising:
embossing a surface comprising a polymer and a plasticizer having
reactive moieties; and reacting the reactive moieties to increase
the glass transition temperature of the embossed polymer
surface.
13. The embossed polymer surface of claim 12, wherein the amount of
reactive plasticizer is effective to raise the glass transition
temperature of the polymer after reaction to reast the glass
transition temperature
14. The embossed polymer surface of claim 12, wherein the polymer
surface comprises a thermoplastic selected from the group
consisting of polyimides, polyetherimides, copolymers of
polyimides, copolymers of polyetherimides, blends of polyimides
with perfluorocarbons, blends of polyetherimides with
perfluorocarbons and combinations comprising at least one of the
foregoing thermoplastics.
15. The embossed polymer surface of claim 12, wherein the polymer
comprises reactive moieties selected from the group consisting of
vinyl substituted aromatic monoamines, polyfunctional alkenyl
aromatic monomers, acryloyl monomers, sulfides, toluidines, ethynyl
groups, ethnyl groups, ethenyl groups, epoxies, fluoroolefins,
alkoxysilanes, and combinations comprising at least one of the
foregoing reactive moieties.
16. An embossed polymer surface formed by: embossing a surface
comprising the reaction product of m-phenylenediamine and a
dianhydride; and treating the embossed polymer to increase the
glass transition temperature of the embossed polymer.
17. The embossed polymer surface of claim 16, wherein the
dianhydride is selected from the group consisting of bisphenol A
dianhydride, 4,4'-oxydiphthalic anhydride, hexafluoroisopropylidene
diphthalic anhydride, and combinations comprising at least one of
the foregoing dianhydrides.
18. The embossed polymer surface of claim 16, wherein the reaction
product is the reaction product of m-phenylenediamine, a
dianhydride, and a terminated siloxane, the reaction product of
m-phenylenediamine, a dianhydride, and polyamic acid.
19. The embossed polymer surface of claim 17, further comprising a
reactive plasticizer.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a division of U.S. application Ser. No.
10/063,407, filed on Apr. 19, 2002, which claims the benefit of
U.S. Provisional Application Ser. No. 60/285,323, filed Apr. 19,
2001, the entire contents of which are incorporated herein by
reference.
BACKGROUND OF INVENTION
[0002] This disclosure relates to the embossing of polymeric
surfaces, and the articles formed thereby.
[0003] Optical, magnetic, and magneto-optic media are primary
sources of high performance storage technology, allowing both high
storage capacity and reasonable cost per megabyte of storage. One
such type of media generally comprises a substrate covered by a
polymer film. The film can be embossed to provide, for example,
pits, grooves, asperities, bit patterns, servo-patterns, and edge
features. The desired surface quality can also be embossed e.g., to
obtain a desired smoothness, roughness, flatness, microwaviness,
and texture, e.g., microtexturing for magnetic grain orientation.
The embossed surface features can have a depth of up to about 200
nanometers (nm). Deeper features or features that vary outside the
ranges can be produced, but, in general, for flying head
applications, these can result in undesirable head-disk
interactions. In the lateral dimension, the surface features,
particularly of a magnetic data storage media, preferably have a
"short" dimension of up to or exceeding about 250 nm, with less
than about 200 nm more preferred, less than about 150 nm even more
preferred, and less than about 100 nm especially preferred.
[0004] It is presently difficult to emboss polymer surfaces having
high glass transition temperatures with nanometer-scale precision
because extremely elevated temperatures (well above the glass
transition) are required to ensure adequate flow and pattern
replication. Under these conditions, there is potential to not only
degrade the polymer surface, but also damage the substrate or
surrounding sensitive layers and features.
[0005] When using either high or low glass transition polymers,
another drawback associated with embossing methods such as hot
stamping is the significant degree of adhesion that can develop
between the embossed polymer surface and the stamping tool. This is
particularly a problem when embossing at high temperatures. Such
adhesion can lead to a number of problems, for example nanoscale
defects and roughness, and gross defects such as film or stamper
damage upon separation. Traditionally, adhesion of this type is
mitigated through the use of mold release agents and other low
surface energy molecules. These may be used as additives in the
polymer, and/or applied topically to the mold surface and/or the
surface of the polymer. While effective, these approaches are not
often compatible with high temperature embossing processes, wherein
the materials can undergo reaction and/or degradation at elevated
temperature. The use of topically applied materials additionally
necessitates reapplication after a relatively low number of molding
cycles, adding to process cost and complexity. Finally, in the case
of sub-micron replicated features, build-up of mold release
additives can lead to poor feature replication.
[0006] There accordingly remains a need in the art for methods and
materials that enable the embossing of polymeric surfaces without
degradation, and/or with nanometer-scale precision, whether at high
or low temperatures.
SUMMARY OF INVENTION
[0007] A method for embossing a surface of a polymer with a first
glass transition temperature (T.sub.g1), the method comprising:
embossing the surface at temperature T.sub.emb; and altering the
T.sub.g1 of the surface to provide a second glass transition
temperature (T.sub.g2), wherein altering is during embossing, after
embossing, or both during and after embossing.
[0008] In another embodiment, a method for improving the release of
a polymeric surface from an embossing tool comprises incorporating
of one or more of fluorine atoms, silicon atoms, or siloxane
segments into the backbone of polymer.
BRIEF DESCRIPTION OF DRAWINGS
[0009] Referring now to the drawings, which are meant to be
exemplary, not limiting:
[0010] FIG. 1 shows an exemplary embodiment of a polymer comprising
reactive sulfide moieties, wherein the glass transition temperature
T.sub.g2 may be increased to a temperature greater than the
embossing temperature T.sub.emb.
[0011] FIG. 2 shows an exemplary embodiment of a polymer comprising
toluidine reactive moieties, wherein the glass transition
temperature T.sub.g2 may be increased to a temperature greater than
the embossing temperature T.sub.emb.
[0012] FIG. 3 shows an exemplary embodiment of a polymer comprising
a reactive plasticizer, wherein the glass transition temperature
T.sub.g2 may be increased to a temperature greater than the
embossing temperature T.sub.emb.
[0013] FIG. 4 shows an exemplary polyamic acid that may be
cured.
DETAILED DESCRIPTION
[0014] Glass transition temperature (hereinafter "Tg") is described
in PRINCIPLES OF POLYMER CHEMISTRY, Flory, Cornell University
Press, Ithaca, N.Y., 1953, pages 52-57. The T.sub.g of a material
can be calculated as described by Fox in Bull. Amer. Physic.
Society, Vol. 1, No. 3, page 123 (1956), and can be measured
experimentally by using a penetrometer such as a DuPont 940
Thermomedian Analyzer. A number of factors can affect the Tg of a
material, including, for example, the identity of the polymer, the
level of crosslinking, processing conditions, and the presence of
additives such as plasticizers, fillers, and the like.
[0015] For purposes of this disclosure, the temperature at which a
material is embossed (the embossing temperature) is denoted as
T.sub.emb, while the glass transition temperature of that material
prior to embossing is denoted as T.sub.g1. T.sub.emb may vary from
slightly lower to slightly higher than the glass transition
temperature T.sub.g1. In accordance with the present method, a
material having a first Tg (T.sub.g1) is embossed, and the material
is treated so as to provide it with a second glass transition
temperature, denoted herein as T.sub.g2. Treatment includes, but is
not limited to, processes such as crosslinking, chain extension,
solvent removal, plasticizer removal, reactive plasticization, and
the like. Such treatment may be concurrent with or subsequent to
the embossing. It is generally desirable for T.sub.g2 to be greater
than T.sub.emb and T.sub.g1. While the present methods find utility
with polymers having a low Tg (typically greater than about
90.degree. C.), they are also useful for polymers having a Tg of
greater than about 120.degree. C., preferably greater than about
150.degree. C., and more preferably greater than about 180.degree.
C. The methods may also be used to emboss high Tg polymers, which
are defined herein as polymers having a Tg greater than or equal to
about 200.degree. C.
[0016] In one embodiment, the Tg of the polymer is depressed
(T.sub.g1), the polymer is embossed, and the Tg of the polymer is
then returned to its typical Tg (T.sub.g2). For example, amorphous
polyimide polymers typically have a Tg of greater than about
200.degree. C. The Tg of polyimides can be temporarily depressed to
T.sub.g1 as the result of a reversible chemical change in the
structure, environment, and the like, of the polymer molecules.
During or following embossing, the factors that caused the
depression of the glass transition to T.sub.g1 are reversed or
removed, thereby allowing the embossed polymer to return to a
higher glass transition temperature T.sub.g2, which is preferably
greater than both T.sub.g1 and T.sub.emb.
[0017] In another embodiment, the Tg of the polymer is not first
adjusted, i.e., the Tg of the material as embossed is T.sub.g1.
Embossing is at or close to T.sub.g1, and during or following
embossing, the Tg of the embossed polymer is adjusted, preferably
raised, to T.sub.g2. For semi-crystalline polymers such as
polyesters, polyamides, and the like, the embossing may be carried
out at a temperature from slightly below the T.sub.g1 to slightly
above the T.sub.g1, for example by crosslinking, curing, or
deplasticization.
[0018] Suitable polymers for embossing include thermoplastics,
thermosets, blends of thermoplastics, thermoplastic copolymers,
blends of thermosets, blends of thermoplastics with thermosets and
the like. Suitable thermoplastics and thermoplastic blends include,
but are not limited to, polyvinyl chloride, polyolefins (including
but not limited to linear and cyclic polyolefins and including
polyethylene, chlorinated polyethylene, polypropylene, and the
like), polyesters (including, but not limited to, polyethylene
terephthalate, polybutylene terephthalate, polycyclohexylmethylene
terephthalate, and the like), polyamides, polysulfones (including
but not limited to hydrogenated polysulfones, and the like),
polyimides, polyether imides, polyether sulfones, polyphenylene
sulfides, polyether ketones, polyether ether ketones,
acrylonitrile-butadiene-styrene (ABS) resins, polystyrenes
(including, but not limited to, hydrogenated polystyrenes,
syndiotactic and atactic polystyrenes, polycyclohexyl ethylene,
styrene-co-acrylonitrile, styrene-co-maleic anhydride, and the
like), polybutadiene, polyacrylates (including, but not limited to,
polymethylmethacrylate, methyl methacrylate-polyimide copolymers,
and the like), polyacrylonitrile, polyacetals, polycarbonates,
polyphenylene ethers (including, but not limited to, those derived
from 2,6-dimethylphenol and copolymers with 2,3,6-trimethylphenol,
and the like), ethylene-vinyl acetate copolymers, polyvinyl
acetate, liquid crystal polymers, ethylene-tetrafluoroethylene
copolymer, aromatic polyesters, polyvinyl fluoride, polyvinylidene
fluoride, polyvinylidene chloride, polytetrafluorethylenes, and the
like, and combinations comprising at least one of the foregoing
thermoplastic polymers.
[0019] Additional specific non-limiting examples of blends of
thermoplastic polymers include
acrylonitrile-butadiene-styrene/nylon,
polycarbonate/acrylonitrile-butadiene-styrene, acrylonitrile
butadiene styrene/polyvinyl chloride, polyphenylene
ether/polystyrene, polyphenylene ether/nylon,
polysulfone/acrylonitrile-butadiene-styrene,
polycarbonate/thermoplastic urethane, polycarbonate/polyethylene
terephthalate, polycarbonate/polybutylene terephthalate,
thermoplastic elastomer alloys, nylon/elastomers,
polyester/elastomers, polyethylene terephthalate/polybutylene
terephthalate, acetal/elastomer, styrene-maleic
anhydride/acrylonitrile-butadiene-styrene, polyimide/polysiloxane,
polyetherimide/polysiloxane, polyether
etherketone/polyethersulfone, polyethylene/nylon,
polyethylene/polyacetal, and the like, and combinations comprising
at least one of the foregoing blends of thermoplastic polymers.
[0020] Suitable thermosetting polymers include but are not limited
to thermosetting resins such as epoxy, phenolics, alkyds,
polyesters, polyurethanes, silicone polymers, mineral filled
silicones, bis-maleimides, cyanate esters, vinyl, benzocyclobutene
polymers, and the like, as well as combinations comprising at least
one of the foregoing thermosetting polymers.
[0021] Additionally, the polymers may comprise blends, copolymers,
mixtures, reaction products, and combinations comprising at least
one of the foregoing thermoplastics and thermosets. Particularly
preferred polymers are polyesters, partly fluorinated polymers such
as perfluorocarbons, polyarylene ethers, polyethersulfones,
polysulfones, polyetherimides, polyimides, polyamidimides, and
polyacetals. Of these, the most preferred for embossing are
polyimides and polyetherimides, copolymers of polyimides and
polyetherimides, and blends of polyimides and polyetherimides with
perfluorocarbons.
[0022] Suitable polyimides have the general formula (I) ##STR1##
wherein a is more than 1, typically about 10 to about 1000 or more,
and more preferably about 10 to about 500; and wherein V is a
tetravalent linker without limitation, as long as the linker does
not impede synthesis or use of the polyimide. Suitable linkers
include but are not limited to: (a) substituted or unsubstituted,
saturated, unsaturated or aromatic monocyclic and polycyclic groups
having about 5 to about 50 carbon atoms, (b) substituted or
unsubstituted, linear or branched, saturated or unsaturated alkyl
groups having about 1 to about 30 carbon atoms; or combinations
thereof. Suitable substitutions and/or linkers include, but are not
limited to, ethers, epoxides, amides, esters, and combinations
thereof. Preferred linkers include but are not limited to
tetravalent aromatic radicals of formula (II), such as ##STR2##
wherein W is a divalent moiety selected from the group consisting
of --O--, --S--, --C(O)--, --SO.sub.2--, --SO--,
--C(CF.sub.3).sub.2--, --C.sub.yH.sub.2y-- (y being an integer from
1 to 5), and halogenated derivatives thereof, including
perfluoroalkylene groups, or a group of the formula --O-Z-O--
wherein the divalent bonds of the --O--or the --O-Z-O-- group are
in the 3,3', 3,4', 4,3', or the 4,4'positions, and wherein Z
includes, but is not limited, to divalent radicals of formula
(III). ##STR3##
[0023] R in formula (I) includes but is not limited to substituted
or unsubstituted divalent organic radicals such as: (a) aromatic
hydrocarbon radicals having about 6 to about 20 carbon atoms and
halogenated derivatives thereof; (b) straight or branched chain
alkylene radicals having about 2 to about 20 carbon atoms; (c)
cycloalkylene radicals having about 3 to about 20 carbon atoms, or
(d) divalent radicals of the general formula (IV) ##STR4## wherein
Q includes but is not limited to a divalent moiety selected from
the group consisting of --O--, --S--, --C(O)--, --SO.sub.2--,
C.sub.yH.sub.2y-- (y being an integer from 1 to 5), and halogenated
derivatives thereof, including perfluoroalkylene groups.
[0024] Preferred classes of polyimides include polyetherimides,
particularly those polyetherimides known in the art which are melt
processable, such as those whose preparation and properties are
described in U.S. Pat. Nos. 3,803,085 and 3,905,942.
[0025] Preferred polyetherimide resins comprise more than 1,
typically about 10 to about 1000 or more, and more preferably about
10 to about 500 structural units, of the formula (V) ##STR5##
wherein T is --O--or a group of the formula --O-Z-O-- wherein the
divalent bonds of the --O-- or the --O-Z-O-- group are in the 3,3',
3,4', 4,3', or the 4,4' positions, and wherein Z includes, but is
not limited, to divalent radicals of formula (III) as defined
above.
[0026] In one embodiment, the polyetherimide may be a copolymer
that, in addition to the etherimide units described above, further
contains polyimide structural units of the formula (VI) ##STR6##
wherein R is as previously defined for formula (I) and M includes,
but is not limited to, radicals of formula (VII). ##STR7##
[0027] Polyetherimides can be prepared by methods well known to
those skilled in the art, including the reaction of an aromatic
bis(ether anhydride) of the formula (VIII) ##STR8## with an organic
diamine of the formula (IX) H.sub.2N--R--NH.sub.2 (IX) wherein T is
defined in formula (V) and R is defined in the formula (I).
[0028] Examples of specific aromatic bis(ether anhydride)s and
organic diamines are disclosed, for example, in U.S. Pat. Nos.
3,972,902 and 4,455,410. Illustrative examples of aromatic
bis(ether anhydride)s of formula (VIII) include: 2,2-bis
[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride;
4,4'-bis(3,4-dicarboxyphenoxy) diphenyl ether dianhydride;
4,4'-bis(3,4-dicarboxyphenoxy) diphenyl sulfide dianhydride;
4,4'-bis(3,4-dicarboxyphenoxy) benzophenone dianhydride;
4,4'-bis(3,4-dicarboxyphenoxy) diphenyl sulfone dianhydride;
2,2-bis[4-(2,3-dicarboxyphenoxy) phenyl]propane dianhydride;
4,4'-bis(2,3-dicarboxyphenoxy) diphenyl ether dianhydride;
4,4'-bis(2,3-dicarboxyphenoxy) diphenyl sulfide dianhydride;
4,4'-bis(2,3-dicarboxyphenoxy) benzophenone dianhydride;
4,4'-bis(2,3-dicarboxyphenoxy) diphenyl sulfone dianhydride;
4-(2,3-dicarboxyphenoxy)-4'-(3,4-dicarboxyphenoxy)
diphenyl-2,2-propane dianhydride;
4-(2,3-dicarboxyphenoxy)-4'-(3,4-dicarboxyphenoxy) diphenyl ether
dianhydride; 4-(2,3-dicarboxyphenoxy)-4'-(3,4-dicarboxyphenoxy)
diphenyl sulfide dianhydride;
4-(2,3-dicarboxyphenoxy)-4'-(3,4-dicarboxyphenoxy) benzophenone
dianhydride and 4-(2,3-dicarboxyphenoxy)-4'-(3,4-dicarboxyphenoxy)
diphenyl sulfone dianhydride, as well as various mixtures
thereof.
[0029] The bis(ether anhydride)s can be prepared by the hydrolysis,
followed by dehydration, of the reaction product of a nitro
substituted phenyl dinitrile with a metal salt of dihydric phenol
compound in the presence of a dipolar, aprotic solvent. A preferred
class of aromatic bis(ether anhydride)s included by formula (VIII)
above includes, but is not limited to, compounds wherein T is of
the formula (X) ##STR9## and the ether linkages, for example, are
preferably in the 3,3', 3,4', 4,3', or 4,4' positions, and mixtures
thereof, and where Q is as defined above.
[0030] Many different diamino compounds may be employed in the
production of polyimides and polyetherimides. Examples of suitable
compounds are ethylenediamine, propylenediamine,
trimethylenediamine, toluenediamine, diethylenetriamine,
triethylenetetramine, hexamethylenediamine, heptamethylenediamine,
octamethylenediamine, nonamethylenediamine, decamethylenediamine,
1,12-dodecanediamine, 1,18-octadecanediamine,
3-methylheptamethylenediamine, 4,4-dimethylheptamethylenediamine,
4-methylnonamethylenediamine, 5-methylnonamethylenediamine,
2,5-dimethylhexamethylenediamine,
2,5-dimethylheptamethylenediamine, 2,2-dimethylpropylenediamine,
N-methyl-bis (3-aminopropyl) amine, 3-methoxyhexamethylenediamine,
1,2-bis(3-aminopropoxy) ethane, bis(3-aminopropyl) sulfide,
1,4-cyclohexanediamine, bis-(4-aminocyclohexyl) methane,
m-phenylenediamine, p-phenylenediamine, 2,4-diaminotoluene,
2,6-diaminotoluene, m-xylylenediamine, p-xylylenediamine,
2-methyl-4,6-diethyl-1,3-phenylene-diamine,
5-methyl-4,6-diethyl-1,3-phenylene-diamine, benzidine,
3,3'-dimethylbenzidine, 3,3'-dimethoxybenzidine,
1,5-diaminonaphthalene, bis(4-aminophenyl) methane,
bis(2-chloro-4-amino-3, 5-diethylphenyl) methane,
bis(4-aminophenyl) propane, 2,4-bis(b-amino-t-butyl) toluene,
bis(p-b-amino-t-butylphenyl) ether, bis(p-b-methyl-o-aminophenyl)
benzene, bis(p-b-methyl-o-aminopentyl) benzene,
1,3-diamino-4-isopropylbenzene, bis(4-aminophenyl) sulfide, bis
(4-aminophenyl) sulfone, bis(4-aminophenyl) ether and
1,3-bis(3-aminopropyl) tetramethyldisiloxane. Mixtures of these
compounds may also be present. The preferred diamino compounds are
aromatic diamines, especially m- and p-phenylenediamine and
mixtures thereof.
[0031] Additional useful structures for preparing polyetherimides
are the dianhydrides shown in formulas VIIIa, VIIIb, and VIIIc
below, where n is about 1 to about 50, ##STR10## as well as the
diamines shown in formulas IXa and IXb below, where n is about 1 to
about 50. ##STR11##
[0032] In another preferred embodiment, the polyetherimide resin
comprises structural units according to formula (V) wherein each R
is independently p-phenylene, m-phenylene, or a mixture thereof and
T is a divalent radical of the formula (XI) ##STR12##
[0033] Included among the many methods of making the polyimides,
particularly polyetherimides, are those disclosed in U.S. Pat. Nos.
3,847,867, 3,814,869, 3,850,885, 3,852,242, 3,855,178, 3,983,093,
and 4,443,591.
[0034] In general, the reactions can be carried out employing
well-known solvents, e.g., o-dichlorobenzene, m-cresol/toluene and
the like, to effect a reaction between the anhydride of formula
(VIII) and the diamine of formula (IX), at temperatures of about
100.degree. C. to about 250.degree. C. Alternatively, the
polyetherimide can be prepared by melt polymerization of aromatic
bis(ether anhydride)s (VIII) and diamines (IX) by heating a mixture
of the starting materials to elevated temperatures with concurrent
stirring. Generally, melt polymerizations employ temperatures of
about 200.degree. C. to about 400.degree. C. Chain stoppers and
branching agents may also be employed in the reaction. When
polyetherimide/polyimide copolymers are employed, a dianhydride,
such as pyromellitic anhydride, is used in combination with the
bis(ether anhydride). The polyetherimide resins can optionally be
prepared from reaction of an aromatic bis(ether anhydride) with an
organic diamine in which the diamine is present in the reaction
mixture at no more than about 0.2 molar excess, and preferably less
than about 0.2 molar excess. Under such conditions the
polyetherimide resin has less than about 15 microequivalents per
gram (.mu.eq/g) acid titratable groups, and preferably less than
about 10 .mu.eq/g acid titratable groups, as shown by titration
with chloroform solution with a solution of 33 weight percent (wt
%) hydrobromic acid in glacial acetic acid. Acid-titratable groups
are essentially due to amine end-groups in the polyetherimide
resin.
[0035] Generally, useful polyetherimides have a melt index of about
0.1 to about 10 grams per minute ("g/min"), as measured by American
Society for Testing Materials ("ASTM") D1238 at 295.degree. C.,
using a 6.6 kilogram ("kg") weight. In a preferred embodiment, the
polyetherimide resin has a weight average molecular weight (Mw) of
about 10,000 to about 150,000 grams per mole ("g/mole"), as
measured by gel permeation chromatography, using a polystyrene
standard. Such polyetherimide resins typically have an intrinsic
viscosity [.eta.] greater than about 0.2 deciliters per gram,
preferably about 0.35 to about 0.7 deciliters per gram measured in
m-cresol at 25.degree. C.
[0036] The polyimides of formula (I) and the polyetherimides of
formula (V) may be copolymerized with other monomers or polymers
such as polysiloxanes, polyesters, polycarbonates, polyacrylates,
fluoropolymers, and the like. Preferred among these are
polysiloxanes having the formula ##STR13## wherein R is the same or
different C.sub.(1-14) monovalent hydrocarbon radical or
C.sub.(1-14) monovalent hydrocarbon radical substituted with
radicals inert during polycondensation or displacement reactions,
and n is an integer from about 1 to about 200. The reactive end
group R.sup.1 is a functionality capable of reacting with the
reactive endgroups on the polyimide of formula (I) or the
polyetherimide of formula (V). Reactive end groups include, for
example, halogen atoms; lower dialkylamino groups of from 2 to
about 20 carbon atoms; lower acyl groups of from 2 to about 20
carbon atoms; lower alkoxy of from 2 to about 20 carbon atoms; and
hydrogen. Particularly preferred siloxane oligomers are those in
which R.sup.1 represents a dimethylamino group, a hydroxyl group,
an acetyl group, or a chlorine atom. U.S. Pat. No. 3,539,657 to
Noshay et al. discloses certain siloxane-polyarylene polyether
block copolymers, and describes, in general and specific terms,
numerous siloxane oligomers having reactive end groups.
[0037] The polyimide-siloxane copolymers used for embossing may be
block or graft copolymers wherein the polysiloxane oligomer is
present in an amount of greater than or equal to about 1,
preferably greater than or equal to about 3, more preferably
greater than or equal to about 5 wt % of the polyimide-siloxane
copolymer. It is generally desirable for the polysiloxane oligomer
to be present in an amount of less than or equal to about 60,
preferably less than or equal to about 45, and more preferably less
than or equal to about 40 wt % of the polyimide-siloxane copolymer.
The reaction between the polyimide oligomer and the siloxane
oligomer is conducted under etherification conditions. Such
conditions generally include a substantially anhydrous, organic
reaction medium, and an elevated temperature. The temperature
advantageously ranges from about 100.degree. C. to about
225.degree. C., preferably from about 150.degree. C. to about
200.degree. C. The reaction is conducted in an inert organic
solvent, and preferred solvents are the non-polar aprotic and polar
aprotic reaction solvents. A particularly preferred reaction
solvent is o-dichlorobenzene. Other suitable methods are set forth
in U. S. Pat. Nos. 4,690,997, 4,808,686, 4,981,894, 5,028,681,
5,104,958, and 5,194,566.
[0038] The embossed polymer surfaces may also include blends of
polyetherimide siloxane copolymer or polyimide siloxane copolymer
with a polyetherimide or a polyimide. The amount of polyetherimide
siloxane copolymer or polyimide siloxane copolymer is preferably
effective to enhance the impact strength of the polymer
composition, and can vary over a fairly wide range. For example,
the copolymer can be present in an amount of greater than or equal
to about 2, preferably greater than or equal to about 5 wt % of the
total polymer composition. Similarly, the copolymer may be present
in an amount of less than or equal to about 90, preferably less
than or equal to about 75, preferably less than or equal to about
35 wt% of the total polymer composition.
[0039] Perfluorocarbon polymers may also be used in blends with the
polymers that are to be embossed. Suitable perfluorocarbon polymers
are thermoplastic fluorinated polyolefins that maybe
semi-crystalline in structure and have a melting point in excess of
about 100.degree. C. They are preferably a polymer of one or more
of perfluorinated monomers containing ethylenic unsaturation and
optionally one or more other compounds containing ethylenic
unsaturation. Suitable monomers include, for example,
perfluorinated monoolefins, such as hexafluoropropylene or
tetrafluoroethylene, and perfluoroalkyl vinyl ethers in which the
alkyl group contains up to six carbon atoms, e.g., perfluoro
(methyl vinyl ether). The monoolefin is preferably a straight or
branched chain compound having a terminal ethylenic double bond and
containing less than six carbon atoms, especially two or three
carbon atoms. The perfluorocarbon polymers also include those in
which portions of the fluorine atoms have been replaced by other
halogen atoms, such as chlorine or bromine. Preferred
perfluorocarbon polymers include polytetrafluoroethylene,
polychlorotrifluoroethylene, polybromotriflurooethylene, and
copolymers thereof. A particularly preferred fluorinated
polyethylene is polytetrafluoroethylene. Other suitable fluorinated
polyolefins include polyperfluoropropane, polyperfluorobutadiene,
polyhexafluoropropylene, fluorinated ethylene propylene copolymer,
and perfluoroalkoxy resin.
[0040] In one embodiment, the molecular weight of preferred
perfluorocarbon polymers is generally less than about 500,000.
Particularly preferred polytetrafluorethylenes having number
average weights of less than about 100,000. The optimal molecular
weight may vary from one perfluorocarbon polymer to another, and
can be determined empirically. The perfluorocarbon polymers are
advantageously dispersed in the thermoplastic matrix. Uniform
dispersion of the perfluorocarbon polymer throughout the matrix
results in products having low adhesion to the mold. Dispersibility
is related to the molecular weight and/or particle size of the
perfluorocarbon polymer. The uniformity of the dispersion of the
perfluorocarbon polymer can be determined by observing the physical
appearance of the molded product or test specimen and by measuring
the degree of elongation at break of the product. Low elongation
values are indicative of poorly dispersed products.
[0041] The perfluorocarbon polymers are employed in particulate
form, preferably in the form of finely divided solids. The
perfluorocarbon polymers may be polymerized to a high molecular
weight and then broken down to a desired lower molecular weight and
particle size by irradiation. Preferred perfluorocarbon polymers
are polymerized in Freon to a desired molecular weight using a
chain stopper. Examples of perfluorocarbon polymers prepared by the
latter procedure are VYDAX.RTM. AR and VYDAX.RTM. 1000, which are
available from E. I. du Pont de Nemours Co., Inc., Wilmington,
Del., U.S.A. An example of a perfluorocarbon polymer prepared by
the irradiation procedure is POLYMIST.RTM. F5A available from
Ausimont, Morristown, N.J. U.S.A.
[0042] The increase in the glass transition temperature to T.sub.g2
either during or after the embossing process may be made, for
example, by physical or chemical crosslinking. Chemical
crosslinking may be achieved by inclusion of reactive moieties in
the embossed polymer that will confer a higher glass transition
temperature to the polymer upon reacting. The reactive moieties may
be physically blended with the polymer or covalently bound to the
polymer, by reaction with the polymer or copolymerization. Suitable
reactive moieties include but are not limited to, vinyl substituted
aromatic monoamines, polyfunctional alkenyl aromatic monomers,
acryloyl monomers, sulfides, pr toluidines, ethynyl, ethnyl or
ethenyl groups, strained ring systems (such as epoxides),
fluoroolefins, alkoxysilanes, and the like. These types of reactive
moieties may function by facilitating crosslinking or chain
extension of the embossed polymer surface, thereby increasing
molecular weight and consequently increasing the glass transition
temperature to T.sub.g2.
[0043] Suitable vinyl substituted aromatic monoamine compounds
include, for example, vinyl aniline, aminophenyl ethylene (APE),
alkyl substituted vinyl substituted anilines such as vinyl
substituted toluidines and xylidines, vinyl substituted
naphthylamines, vinyl substituted monoamino substituted biphenyls,
and the like. Aminophenyl ethylene (APE) is preferred.
[0044] When the embossed polymer comprises a polyarylene ether, a
preferred reactive moiety is a polyfunctional alkenyl aromatic
monomer. Polyfunctional alkenyl aromatic monomer may generally be
used as reactive moieties when polyarylene ethers are used in the
embossed surface. Suitable polyfunctional alkenyl aromatic monomer
may have the structure (XIII): ##STR14## wherein each R.sup.16 is
independently hydrogen, C.sub.1-C.sub.12 alkyl, C.sub.2-C.sub.12
alkenyl, C.sub.2-C.sub.12 alkynyl, C.sub.6-C.sub.18 aryl, or the
like; each R.sup.17 is independently halogen, C.sub.1-C.sub.12
alkyl, C.sub.1-C.sub.12 alkoxyl, C.sub.6-C.sub.18 aryl, or the
like; p is 2 to 4; and q is 0 to 4. Suitable polyfunctional alkenyl
aromatic monomers include those such as 1,2-divinylbenzene,
1,3-divinylbenzene, 1,4-divinylbenzene, trivinylbenzenes,
1,3-diisopropenylbenzene, 1,4-diisopropenylbenzene, and the like;
and mixtures comprising at least one of the foregoing alkenyl
aromatic monomers. In the foregoing for which no substituent
position is specified, the substituents may occupy any free
position on the aromatic ring.
[0045] In one embodiment, a suitable polyfunctional acryloyl
reactive moiety comprises at least two acryloyl groups having the
structure (XIV): ##STR15## wherein R.sup.18 and R.sup.19 are each
independently hydrogen, C.sub.1-C.sub.12 alkyl, or the like; and
wherein R.sup.18 and R.sup.19 may be disposed either cis or trans
about the carbon-carbon double bond. Preferably, R.sup.18 and
R.sup.19 are each independently hydrogen or methyl.
[0046] Suitable polyfunctional acryloyl reactive moieties of this
type include, for example, unsaturated polyester resins that are
the polycondensation reaction product of one or more dihydric
alcohols and one or more ethylenically unsaturated polycarboxylic
acids. By polycarboxylic acid is meant polycarboxylic or
dicarboxylic acids or anhydrides, polycarboxylic or dicarboxylic
acid halides, and polycarboxylic or dicarboxylic esters. For
example, suitable unsaturated polycarboxylic acids, and the
corresponding anhydrides and the acid halides that contain
polymerizable carbon-to-carbon double bonds, may include maleic
anhydride, maleic acid, and fumaric acid. A minor proportion of the
unsaturated acid, up to about forty mole percent, may be replaced
by dicarboxylic or polycarboxylic acid that does not contain a
polymerizable carbon-to-carbon bond. Examples thereof include the
acids (and corresponding anhydrides and acid halides):
orthophthalic, isophthalic, terephthalic, succinic, adipic,
sebacic, methylsuccinic, and the like. Dihydric alcohols that are
useful in preparing the polyesters include, for example,
1,2-propane diol (hereinafter referred to as propylene glycol),
dipropylene glycol, diethylene glycol, 1,3-butanediol, ethylene
glycol, glycerol, and the like. Examples of suitable unsaturated
polyesters are the polycondensation products of (1) propylene
glycol and maleic and/or fumaric acids; (2) 1,3-butanediol and
maleic and/or fumaric acids; (3) combinations of ethylene and
propylene glycols (approximately 50 mole percent or less of
ethylene glycol) and maleic and/or fumaric acids; (4) propylene
glycol, maleic and/or fumaric acids and dicyclopentadiene reacted
with water; and the like; and mixtures comprising at least one of
the foregoing polyfunctional acryloyl monomers. In addition to the
above-described polyesters, dicyclopentadiene modified unsaturated
polyester resins such as those described in U.S. Pat. No. 3,883,612
to Pratt et al. may be used. The molecular weight of the
polymerizable unsaturated polyester may vary over a considerable
range, but ordinarily useful polyesters have a number average
molecular weight of about 300 AMU to about 5,000 AMU, and more
preferably about 500 AMU to about 5,000 AMU.
[0047] In another embodiment, the polyfunctional acryloyl reactive
moiety is a monomer comprising at least two acryloyl moieties
having the structure (XV): ##STR16## wherein R.sup.20-R.sup.22 are
each independently hydrogen, C.sub.1-C.sub.12 alkyl,
C.sub.2-C.sub.12 alkenyl, C.sub.6-C.sub.18 aryl, C.sub.7-C.sub.18
alkyl-substituted aryl, C.sub.7-C.sub.18 aryl-substituted alkyl,
C.sub.2-C.sub.12 alkoxycarbonyl, C.sub.7-C.sub.18 aryloxycarbonyl,
C.sub.8-C.sub.18 alkyl-substituted aryloxycarbonyl,
C.sub.8-C.sub.18 aryl-substituted alkoxycarbonyl, nitrile, formyl,
carboxylate, imidate, thiocarboxylate, or the like. Preferably,
R.sup.20-R.sup.22 are each independently hydrogen or methyl.
[0048] Suitable polyfunctional acryloyl monomers further include,
for example, compounds produced by condensation of an acrylic or
methacrylic acid with a di-epoxide, such as bisphenol-A diglycidyl
ether, butanediol diglycidyl ether, or neopenylene glycol
dimethacrylate. Specific examples include 1,4-butanediol
diglycidylether di(meth)acrylate, bisphenol A diglycidylether
dimethacrylate, and neopentylglycol diglycidylether
di(meth)acrylate, and the like. Also included as polyfunctional
acryloyl monomers are the condensation of reactive acrylate or
methacrylate compounds with alcohols or amines to produce the
resulting polyfunctional acrylates or polyfunctional acrylamides.
Examples include N,N-bis(2-hydroxyethyl)(meth)acrylamide,
methylenebis((meth)acrylamide),
1,6-hexamethylenebis((meth)acrylamide), diethylenetriamine
tris((meth)acrylamide), bis(gamma-((meth)acrylamide)propoxy)
ethane, beta-((meth)acrylamide) ethylacrylate, ethylene glycol
di((meth)acrylate)), diethylene glycol di(meth)acrylate,
tetraethylene glycol di(meth)acrylateglycerol di(meth)acrylate,
glycerol tri(meth)acrylate, 1,3-propylene glycol di(meth)acrylate,
dipropyleneglycol di(meth)acrylate, 1,4-butanediol
di(meth)acrylate, 1,2,4-butanetriol tri(meth)acrylate,
1,6-hexanedioldi(meth)acrylate, 1,4-cyclohexanediol
di(meth)acrylate, 1,4-benzenediol di(meth)acrylate,
pentaerythritoltetra(meth)acrylate, 1,5-pentanediol
di(meth)acrylate, trimethylolpropane di(meth)acrylate,
trimethylolpropane tri(meth)acrylate),
1,3,5-triacryloylhexahydro-1,3,5-triazine,
2,2-bis(4-(2-(meth)acryloxyethoxy)phenyl)propane,
2,2-bis(4-(2-(meth)acryloxyethoxy)-3,5-dibromophenyl)propane,
2,2-bis((4-(meth)acryloxy)phenyl)propane,
2,2-bis((4-(meth)acryloxy)-3,5-dibromophenyl)propane, and the like,
and mixtures comprising at least one of the foregoing
polyfunctional acryloyl monomers. It will be understood that the
suffix (meth)acryl- denotes either acryl- or methacryl-.
[0049] Preferred polyfunctional acryloyl monomers include
trimethylolpropane tri(meth)acrylate, 1,6-hexanediol
di(meth)acrylate, ethylene glycol di(meth)acrylate, propylene
glycol di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate,
butanedioldi(meth)acrylate, diethylene glycol di(meth)acrylate,
triethylene glycol di(meth)acrylate, and the like, and mixtures
comprising at least one of the foregoing polyfunctional acryloyl
monomers.
[0050] Sulfides may also be utilized as reactive moieties for
increasing the T.sub.g of the polymer surface to be embossed. Chief
among the sulfides are polyarylene sulfides having halogen
termination, for example those having the formula
XR--(SR).sub.n+2--X wherein R is a C(6-14) arylene radical, or
C(6-14) arylene radical substituted with radicals inert during
displacement, X is a halogen radical such as chloro and n is 0 to
50.
[0051] Amino terminated polyarylene sulfides having the formula
H.sub.2RN-(SR).sub.n+2--NH.sub.2 may also be used, wherein R and n
are as defined above. Amino terminated polyarylene sulfides can be
made by effecting a reaction between halogen-terminated polyarylene
sulfide and an amino thio-arylol, in the presence of an acid
acceptor, such as an alkali metal carbonate to produce the
corresponding terminated polyarylene sulfide shown above. Details
of making the polyarylene sulfides and incorporating them into
various polyimides, polyetherimides and polyetherimide-siloxane
copolymers are available in U.S. Pat. Nos. 4,609,712 and
5,194,566.
[0052] Ethynyl end capping may also be used to increase the Tg of
the polymer. Ethynyl endcapping is typically carried out using
4-ethynylbenzoyl chloride and can generally be used for end-capping
polymers having terminal groups that react with acid chlorides,
such as hydroxyl, amine, amide and similar groups. U.S. Pat. Nos.
4,431,761, 4,567,240 and 4,638,083 detail the reactions of
4-ethynylbenzoyl chloride with various oligomer and polymers to
produce ethynyl end caps. Ethynyl terminated polyimides are
detailed in U.S. Pat. Nos. 4,098,767 and 4,100,138.
[0053] Epoxy functional materials suitable for use as reactive
moieties may contain aliphatic, cycloaliphatic, or aromatic epoxy
groups, and may be monomeric, dimeric, oligomeric, or polymeric
materials having at least one epoxy group. Generally, epoxy
functional reactive moieties suitable for use herein are derived by
the reaction of an epoxidizing agent, such as peracetic acid, and
an aliphatic or cycloaliphatic point of unsaturation in a molecule.
Other functionalities that will not interfere with the epoxidizing
action of the epoxidizing agent may also be present in the
molecule, for example, esters, ethers, hydroxy, ketones, halogens,
aromatic rings, and the like. A well-known class of epoxy
functionalized reactive moieties are glycidyl ethers of aliphatic
or cycloaliphatic alcohols or aromatic phenols. The alcohols or
phenols may have more than one hydroxyl group. Suitable glycidyl
ethers may be produced by the reaction of, for example, monophenols
or diphenols such as bisphenol-A with epichlorohydrin. Polymeric
aliphatic epoxides might include, for example, copolymers of
glycidyl methacrylate or allyl glycidyl ether with methyl
methacrylate, styrene, acrylic esters, or acrylonitrile. Other
classes of curable epoxy containing polymers are epoxy-siloxane
resins, epoxy-polyurethanes, and epoxy-polyesters Such polymers
usually have epoxy functional groups at the ends of their chains.
Epoxy-siloxane resins and method for making are more particularly
shown by E. P. Plueddemann and G. Fanger, J. Am. Chem. Soc. 80,
632-635 (1959). As described in the literature, epoxy resins can
also be modified in a number of standard ways such as by reaction
with amines, carboxylic acids, thiols, phenols, alcohols, and the
like, as shown in U.S. Pat. Nos. 2,935,488; 3,235,620; 3,369,055;
3,379,653; 3,398,211; 3,403,199; 3,563,850; 3,567,797; and
3,677,995. Further examples of useful epoxy resins are shown in the
Encyclopedia of Polymer Science and Technology, Vol 6, 1967,
Interscience Publishers, New York, pp 209-271.
[0054] Specifically, the epoxies that can be employed herein
include glycidol, bisphenol-A diglycidyl ether,
tetrabromobisphenol-A diglycidyl ether, diglycidyl ester of
phthalic acid, diglycidyl ester of hexahydrophthalic acid,
epoxidized soybean oil, butadiene diepoxide, tetraphenylethylene
epoxide, dicyclopentadiene dioxide, vinylcyclohexene dioxide,
bis(3,4-epoxy-6-methylcyclohexylmethyl) adipate, and
3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate.
[0055] Suitable epoxy functionalized materials are available from
Dow Chemical Company under the tradename DER-332; from Shell Oil
Corporation under the trade names EPON 826, 828, and 871; from
Ciba-Giegy Corporation under the trade names CY-182 and CY-183; and
from Union Carbide under the tradename ERL-4221.
[0056] The reactive moieties may generally be present in an amount
of greater than or equal to about 0.1, preferably greater than or
equal to about 1, more preferably greater than or equal to about 3,
most preferably greater than or equal to about 5 wt % of the total
composition. It is generally desirable to have the reactive
moieties present in an amount of less than or equal to about 30,
preferably less than or equal to about 20, more preferably less
than or equal to about 15, and most preferably less than or equal
to, about 12 wt % of the total composition.
[0057] Reaction may occur by heat treatment, ultraviolet
irradiation, e-beam irradiation, oxidation, catalytic action, and
the like, depending on the particular reactive moiety used. For
example, the polymer may optionally further comprise a curing
catalyst to increase the curing rate. Curing catalysts, also
referred to as initiators, are well known to the art, and are used
to initiate the polymerization, cure, or crosslink thermoplastics
and thermosets, including unsaturated polyester, vinyl ester, and
allylic thermosets. Non-limiting examples of curing catalysts are
those described in "Plastic Additives Handbook, 5.sup.th Edition"
Hans Zweifel, Ed, Carl Hanser Verlag Publishers, Munich, 2001, and
in U.S. Pat. Nos. 5,407,972 to Smith et al., and 5,218,030 to
Katayose et al.
[0058] Suitable curing catalyst for the unsaturated portion of the
thermoset are those capable of producing radicals at elevated
temperatures. Such curing catalysts may include both peroxy and
non-peroxy based radical initiators. Examples of useful peroxy
initiators include, for example, benzoyl peroxide, dicumyl
peroxide, methyl ethyl ketone peroxide, lauryl peroxide,
cyclohexanone peroxide, t-butyl hydroperoxide, t-butyl benzene
hydroperoxide, t-butyl peroctoate,
2,5-dimethylhexane-2,5-dihydroperoxide,
2,5-dimethyl-2,5-di(t-butylperoxy)-hex-3-yne, di-t-butylperoxide,
t-butylcumyl peroxide,
.alpha.,.alpha.'-bis(t-butylperoxy-m-isopropyl)benzene,
2,5-dimethyl-2,5-di(t-butylperoxy)hexane, dicumylperoxide,
di(t-butylperoxy isophthalate, t-butylperoxybenzoate,
2,2-bis(t-butylperoxy)butane, 2,2-bis(t-butylperoxy)octane,
2,5-dimethyl-2,5-di(benzoylperoxy)hexane,
di(trimethylsilyl)peroxide, trimethylsilylphenyltriphenylsilyl
peroxide, and the like, and mixtures comprising at least one of the
foregoing curing catalysts. Typical non-peroxy initiators include,
for example, 2,3-dimethyl-2,3-diphenylbutane,
2,3-trimethylsilyloxy-2,3-diphenylbutane, and the like, and
mixtures comprising at least one of the foregoing curing catalysts.
In a preferred embodiment, the curing catalyst may comprise t-butyl
peroxybenzoate or methyl ethyl ketone peroxide.
[0059] The curing catalyst may promote curing at a temperature of
about 0.degree. C. to about 250.degree. C. When present, the curing
catalyst may be used in an amount of at least about 0.1, preferably
at least about 1 wt %, of the total composition. The curing
catalyst may be used in an amount of up to about 10, preferably up
to about 5, more preferably up to about 3 wt % of the total
composition.
[0060] As stated above, polyimides, polyetherimides, and blends
comprising polyimides and polyetherimides are particularly suitable
for the incorporation of reactive moieties. For example, as shown
in FIG. 1, arylene sulfide moieties may be incorporated into a
polyimide backbone. After embossing, the sulfur atom may be
converted to a higher oxidation state (sulfoxide and/or sulfone) by
heating in air. These polyimides are available by appropriate
selection of starting monomers and reaction conditions as outlined
above. Methods for the conversion of sulfides in polyimide films
are described in U.S. Pat. No. 4,609,712.
[0061] Another example is shown in FIG. 2, wherein toluenediamine
moieties are incorporated into a polyimide backbone. After
embossing, crosslinking may be effected by heating in air. These
polyimides are available by appropriate selection of starting
monomers and reaction conditions as outlined above.
[0062] In accordance with another embodiment, a reactive
plasticizer may be incorporated into a polymer having a high Tg in
an amount effective to lower the glass transition temperature of
the polymer, to T.sub.g1. The polymer having T.sub.g1 is then
embossed at a temperature T.sub.emb, wherein T.sub.emb may be
slightly above or slightly lower than T.sub.g1. The plasticizer may
be cured during or after embossing, thereby increasing the glass
transition temperature of the polymer to T.sub.g2. Alternatively,
the plasticizer may be removed from the embossed polymer to achieve
T.sub.g2.
[0063] An example of this approach is shown in FIG. 3, wherein a
polyimide comprising a reactive alkene moiety, together with a
plasticizer, is embossed and then crosslinked to form a polymer
having a glass transition temperature T.sub.g2. When polyimides or
polyetherimides are used as the embossed polymer, it is desirable
to use a bis-biphenylene additive having a 4-membered ring as the
reactive plasticizer. The bis-biphenylene additive undergoes ring
scission at an elevated temperature. The reactive plasticizer is
preferably of the formula A-R-A where A is a reactive functionality
such vinyl substituted aromatic monoamines, polyfunctional alkenyl
aromatic monomers, acryloyl monomers, sulfides, toluidines, ethynyl
groups, ethyl groups, ethenyl groups, epoxies, fluoroolefins,
alkoxysilanes, and combinations comprising at least one of the
reactive functionalities, and R is a monomeric or oligomeric
polyimide repeat unit such as shown in the formula (XVIII)
##STR17## wherein Y is --O-- or a group of the formula --O-Z-O--
wherein the divalent bonds of the --O-- or the --O-Z-O-- group are
in the 3,3', 3,4', 4,3', or the 4,4' positions, and wherein Z
includes, but is not limited, to divalent radicals of formula (III)
as defined above, n is an integer from 0 to about 5 and Ar is an
aromatic groups from which diamines are obtained such as
m-phenylene, p-phenylene, diphenylether-4,4'-yl, and the like.
[0064] Suitable examples of reactive plasticizers are shown in
formulas (XIXa) and (XIXb) below: ##STR18##
[0065] Other reactive moieties are shown in formulas (XIXc) below
wherein R is a moiety having aromatic groups, and preferably R has
from 36 to 60 carbon atoms. ##STR19##
[0066] It is generally desirable for the reactive moieties to be
present in an amount greater than or equal to about 5, preferably
greater than or equal to about 7, more preferably greater than or
equal to about 10 wt % of the total polymer composition. It is
desirable for the reactive moieties to be present in an amount of
less than or equal to about 25, preferably less than or equal to
about 23, more preferably less than or equal to about 20 wt % of
the total composition.
[0067] In another embodiment, the incorporation of fluorine atoms,
silicon atoms, or siloxane segments into the backbone of polymer
improves the release of a polymeric surface from an embossing tool.
For polyimides, this may be achieved by use of one or more of the
diamine or dianhydride structures of formula VIIIa, VIIIc, IXa, or
IXb. The degree of release may be adjusted by variation in the
identity and quantity of the fluorine and/or silicone atom
containing monomers. Additionally, the polymer containing the
fluorine atom, silicone atom or siloxane segments may be blended
with perfluorocarbon polymers described above in order to adjust
the degree of release. If adhesion is desired in lieu of release,
then adhesion promoters may be used as described below.
[0068] In another embodiment, a polyimide comprising one or more of
fluorine atoms, silicon atoms, or siloxane segments is achieved by
applying the polyimide in polyamic acid form; and curing the
applied polyamic acid. This method can also be used to adjust the
degree of release from the stamper during the embossing process but
also improves adhesion of the embossed polymer surface to the
substrate. An exemplary polyamic acid is shown in FIG. 4. Cure of
polyamic acids is readily effected by heat treatment of the coated
polyamic acid with or by chemical imidization using an acid
anhydride/tertiary amine combination, such as acetic
anhydride/triethylamine.
[0069] Still another embodiment is directed to embossed films
produced by one or more of the above-described methods. These
methods are particularly suited for the production of optical,
magnetic, and magneto-optic data storage media. Production of such
patterned media generally comprises disposing a polymer layer
having T.sub.g1 on at least a portion of a substrate (e.g., the
data storage media or disk), embossing at least a portion of the
polymer layer, optionally removing at least a portion of the
polymer coating to expose at least a portion of the substrate,
applying one or more desired layer(s) to at least a portion of the
substrate, and optionally removing at least a portion, and
optionally all, of the remaining polymer coating. Conversion to
T.sub.g2 may occur at any point in the process during or after
embossing.
[0070] Suitable substrates are known, for example metal, (e.g.,
aluminum), glass, ceramic, polymer, metal-matrix composite, and
alloys and combinations comprising at least one of the foregoing,
and the like). In theory, the substrate can comprise any polymer
that exhibits appropriate properties, e.g., the polymer is capable
of withstanding the subsequent processing parameters (e.g.,
application of subsequent layers) such as sputtering (i.e.,
temperatures of room temperature up to and exceeding about
200.degree. C. (typically up to or exceeding about 250.degree. C.)
for magnetic media, and temperatures of about room temperature
(about 25.degree. C.) up to about 150.degree. C. for magneto-optic
media). That is, it is desirable for the polymer to have sufficient
thermal stability to prevent deformation during the deposition
steps.
[0071] Coating of the substrate with the polymer can be
accomplished by a number of methods as is readily understood by an
artisan. Exemplary coating techniques include spin coating, vapor
deposition (e.g., plasma enhanced chemical vapor deposition, and
the like), electrodeposition coating, meniscus coating, spray
coating, extrusion coating, and the like, and combinations
comprising at least one of the foregoing techniques.
[0072] In order to improve adhesion of the coating to the
substrate, optionally, an adhesion promoter, such as an
organosilane or another conventional adhesion promoter, can be
used. If an adhesion promoter is employed, it is typically
dissolved in a solvent, such as methanol, water, and combinations
comprising at least one of the foregoing solvents, and is applied
to the disk prior to applying the polymer. Once the adhesion
promoter is spin coated onto the disk, the polymer coating is
applied as described above.
[0073] Embossing by hot pressing is preferred, in order to achieve
sub-micron scale patterning. The mold is preferably preheated to a
temperature that, in conjunction with the temperature of the
substrate, is capable of embossing the desired surface features
onto the polymer surface of the substrate. The mold temperature can
be at, above, or below the T.sub.g1 of the polymer to be embossed.
If the mold temperature is above the T.sub.g1, it is preferred the
mold temperature be within about 30.degree. C., preferably within
about 15.degree. C., and more preferably within about 10.degree. C.
of T.sub.g1. Alternatively, the mold is preferably at or below
T.sub.g1 of the polymer to be embossed, within about 10.degree. C.
(especially for amorphous materials), more preferably within about
5.degree. C. (especially for amorphous materials), even more
preferably within about 2.degree. C. below T.sub.g1 (especially for
crystalline materials).
[0074] In addition to heating the mold, the coated substrate may be
heated to a temperature greater than the T.sub.g1 of the polymeric
surface to be embossed, preferably a temperature that facilitates
replication of the geographic locators and/or other surface
features on the substrate. Typically, the substrate is heated to
within about 5.degree. C. above T.sub.g1 for crystalline material,
and within about 10.degree. C. for amorphous materials.
[0075] Once the substrate has attained the desired temperature, it
is placed in the mold and pressure is applied. After placing the
substrate in the mold the temperature thereof can be maintained,
increased or decreased as necessary in order to optimize
replication and enable substrate release from the mold while
maintaining the integrity of the surface features. Typically in
order to maintain the integrity of the surface features, the molded
substrate is cooled to below the glass transition temperature
T.sub.g1 prior to removal from the mold. Not to be limited by
theory, due to the rheology of the polymer, not only can pits,
grooves, bumps, bit patterns, servo-patterns, and edge features be
embossed into the substrate, but the desired surface quality can
also be embossed, e.g., the desired smoothness, roughness,
flatness, microwaviness, and texturing (e.g., microtexturing for
magnetic grain orientation). The embossed surface features can have
a depth of up to about 200 nm, although greater depths may also be
achived, for example up to about 210, or even 25 nm. Typically a
depth of about 10 nm, preferably about 20 nm, to about 150 nm,
preferably to about 50 nm, can be employed. In the lateral
dimension, the surface features, particularly of a magnetic data
storage media, would preferably have a "short" dimension of up to
or exceeding about 250 nm, with less than about 200 nm more
preferred, less than about 150 nm even more preferred, and less
than about 100 nm especially preferred.
[0076] The embodiments described above are exemplified by the
following non-limiting examples:
Preparation of ODPA-MPD Polyamic Acid.
[0077] A dry 250 ml 3-neck flask equipped with a mechanical
stirrer, condenser and a nitrogen inlet was charged with 2.7 gm
(0.025 mol) of m-phenylenediamine (MPD) and 20 ml of dry
N-methyl-2-pyrollidone (NMP). The mixture was stirred until all the
MPD dissolved at which point a solid mixture of 7.595 gm (0.0245
mol) of 4,4'-oxydiphthalic anhydride (ODPA) and 0.148 gm (0.001
mol) of phthalic anhydride was added in small portions over a 30
minute period. Solids adhering to the funnel and walls of the flask
were washed down with an additional 12 ml of NMP. The resulting
mixture became homogeneous after several hours and was stirred
overnight at room temperature then stored in a refrigerator. A
small sample of this solution was drawn on a clean, dry glass plate
to a thickness of 254 micrometers by means of a doctor blade. The
film was transferred to a vacuum oven where it was heated at
75.degree. C. for 1 hour then for 1 hour each at 150.degree. C.,
200.degree. C., and 300.degree. C. The resulting polymer film was
tough, flexible and exhibited a T.sub.g2 of 296.4.degree. C. as
measured by differential scanning calorimetry.
Preparation of 6FDA-MPD.
[0078] In a similar fashion to that described above, condensation
of 2.7 gm (0.025 mol) of MPD with 10.88 gm (0.0245 mol) of
hexafluoroisopropylidene diphthalic anhydride (6FDA) and 0.148 gm
(0.001 mol) of phthalic anhydride in 40 mL of dry NMP afforded a
polyamic acid solution from which a polymer film having a T.sub.g2
of 298.7.degree. C. was obtained as measured by differential
scanning calorimetry.
Preparation of ODPA/MPD/G-10 (97.5/2.5).
[0079] A dry 250 ml 3-neck flask equipped with a mechanical
stirrer, condenser and a nitrogen inlet was charged with 2.422 gm
(0.0224 mol) of m-phenylenediamine (MPD), 0.549 gm (0.006 mol) of
an amine terminated siloxane (G-10), having 10 repeat units and a
molecular weight of 954 g/mole and 20 ml of dry
N-methyl-2-pyrollidone (NMP). The mixture was stirred until the
amines dissolved at which point 7.13 gm (0.023 mol) of solid
4,4'-oxydiphthalic anhydride (ODPA) was added in small portions
over a 30 minute period. Solids adhering to the funnel and walls of
the flask were washed down with an additional 12 ml of NMP. The
resulting mixture became homogeneous after several hours and was
stirred overnight at room temperature then stored in a
refrigerator. A small sample of this solution was drawn on a clean,
dry glass plate to a thickness of about 254 microns by means of a
doctor blade. The film was transferred to a vacuum oven where it
was heated at 75.degree. C. for 1 hour then for 1 hour each at
150.degree. C., 200.degree. C., and 300.degree. C. The resulting
polymer film was tough, flexible and exhibited a T.sub.g2 of
272.8.degree. C. as measured by differential scanning
calorimetry.
Preparation of BPADA/MPD/G-10 (97.5/2.5)
[0080] A dry 250 ml 3-neck flask equipped with a mechanical
stirrer, condenser and a nitrogen inlet was charged with 2.422 gm
(0.0224 mol) of m-phenylenediamine (MPD), 0.549 gm (0.006 mol) of
an amine terminated siloxane (G-10), having a molecular weight of
954 g/mole and 20 ml of dry N-methyl-2-pyrollidone (NMP). The
mixture was stirred until the amines dissolved at which point 7.13
gm (0.023 mol) of solid Bisphenol A dianhydride (BPADA) was added
in small portions over a 30 minute period. Solids adhering to the
funnel and walls of the flask were washed down with an additional
12 ml of NMP. The resulting mixture became homogeneous after
several hours and was stirred overnight at room temperature then
stored in a refrigerator. A small sample of this solution was drawn
on a clean, dry glass plate to a thickness of about 254 microns by
means of a doctor blade. The film was transferred to a vacuum oven
where it was heated at 75.degree. C. for 1 hour then for 1 hour
each at 150.degree. C., 200.degree. C., and 300.degree. C.
respectively. The resulting polymer film was tough, flexible and
exhibited a T.sub.g2 of 215.degree. C. as measured by differential
scanning calorimetry.
EXAMPLES 1-9
[0081] Examples 1-9 are representative materials prepared by these
processes and are presented in the Table. Example 1 is a
polyetherimide obtained by the reaction product of ODPA and MPD,
having a T.sub.g2 of 296.degree. C. Examples 2 and 3 show the
addition of a polysiloxane to the reaction product of ODPA and MPA.
The incorporation of the (G10) dimethylamine-terminated
polysiloxane to the polyetherimide backbone in amounts of 2.5 and 5
wt % respectively appears to depress the glass transition
temperature. Example 4 represents a polyetherimide obtained as the
reaction of ODPA, 2 wt % phthalic anhydride disiloxane (PADS) and
MPD. Example 5 shows that the polyetherimide reaction product of
6FDA and MPD has a glass transition temperature of 299.degree. C.
Similarly the polyetherimide reaction product of BPADA with MPD
shows a T.sub.g depression when copolymerized with polysiloxane.
This is reflected in examples 7,8, and 9. TABLE-US-00001
Diamine/Siloxane Example Dianhydride(s) (Weight Ratio) Tg (.degree.
C.) 1 ODPA MPD 296 2 ODPA MPD/G10 (97.5/2.5) 273 3 ODPA MPD/G10
(95/5) ND* 4 ODPA/PADS (98/2) MPD 289 5 6FDA MPD 299 6 BPADA MPD
215 7 BPADA MPD/G10 (95/5) 201 8 BPADA MPD/G10 (90/10) 195 9 BPADA
MPD/G20** (95/5) 204 *ND = not detectable **G20 has 20 siloxane
repeat units.
EXAMPLE 10
[0082] Pyralin 2611 a commercially available polyimide (from HD
Microsystems) in polyamic acid form in NMP solvent was coated onto
a glass substrate. The coated disk was then soft-baked at
150.degree. C. for 2 hours whereupon the disk was placed in an
embossing press and embossed at 150.degree. C. with an optical disk
stamper having a digital versatile disk (DVD) format. Following
embossing, the disk was placed in an oven which was ramped from 150
to 300.degree. C. over 1 hour and held at 300.degree. C. for 1 hour
to cure the polymer. Once baked the polymer possessed a glass
transition temperature T.sub.g2 of greater than 300.degree. C. and
the pre-embossed pattern was maintained. In contrast, embossing of
a pre-cured Pyralin 2611 polymer at 150.degree. C. resulted in no
pattern transfer.
[0083] The method of embossing described in the above embodiments
provides several advantages that allow the production of improved
embossed surfaces. Defects caused by thermal and chemical
decomposition are minimized. Production defects caused by adhesion
of the embossed polymeric surface to the stamper or embossing tool
are reduced. Use of the polymers and methods described above allows
the fabrication of articles of high performance, high .sub.g
materials, particularly those wherein the T.sub.g is greater than
about 200.degree. C., with improved surface feature definition.
Lower temperatures may be used for embossing, resulting in an
energy savings. This method may be used in the production of
interdigitated electrodes, photoresists, optical, magnetic, and
magneto-optical media.
[0084] All patents and other references mentioned herein are
incorporated by reference in their entirety.
[0085] While the invention has been described with reference to an
exemplary embodiment, it will be understood by those skilled in the
art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications may be made to
adapt a particular situation or material to the teachings of the
invention without departing from the essential scope thereof.
Therefore, it is intended that the invention not be limited to the
particular embodiment disclosed as the best mode contemplated for
carrying out this invention, but that the invention will include
all embodiments falling within the scope of the appended
claims.
* * * * *