U.S. patent application number 13/504810 was filed with the patent office on 2012-11-15 for optical device with antistatic property.
Invention is credited to Mahfuza B. Ali, Brandt K. Carter, Michael K. Gerlach, Thomas P. Klun, Mark J. Pellerite, Thomas M. Snyder.
Application Number | 20120288675 13/504810 |
Document ID | / |
Family ID | 43922983 |
Filed Date | 2012-11-15 |
United States Patent
Application |
20120288675 |
Kind Code |
A1 |
Klun; Thomas P. ; et
al. |
November 15, 2012 |
OPTICAL DEVICE WITH ANTISTATIC PROPERTY
Abstract
An optical device having a first optical member, a second
optical member, and an antistatic layer disposed between the first
optical member and the second optical member wherein the antistatic
layer contains the reaction product of a mixture comprising at
least one polymerizable onium salt having an anion and at least one
non-onium polymerizable monomer, oligomer, or polymer.
Inventors: |
Klun; Thomas P.; (Lakeland,
MN) ; Carter; Brandt K.; (Woodbury, MN) ;
Gerlach; Michael K.; (Huntsville, AL) ; Ali; Mahfuza
B.; (Mendota Heights, MN) ; Pellerite; Mark J.;
(Woodbury, MN) ; Snyder; Thomas M.; (St. Paul,
MN) |
Family ID: |
43922983 |
Appl. No.: |
13/504810 |
Filed: |
October 28, 2010 |
PCT Filed: |
October 28, 2010 |
PCT NO: |
PCT/US10/54509 |
371 Date: |
July 31, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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61256641 |
Oct 30, 2009 |
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Current U.S.
Class: |
428/141 ;
428/339; 428/411.1; 428/425.9; 428/473.5; 428/521; 428/522;
428/704 |
Current CPC
Class: |
Y10T 428/31504 20150401;
C09D 4/00 20130101; C08F 222/1006 20130101; Y10T 428/269 20150115;
Y10T 428/24355 20150115; C08F 220/30 20130101; Y10T 428/31721
20150401; Y10T 428/31931 20150401; Y10T 428/31935 20150401; Y10T
428/31609 20150401; C08F 222/1006 20130101; C08F 220/30
20130101 |
Class at
Publication: |
428/141 ;
428/411.1; 428/473.5; 428/704; 428/521; 428/425.9; 428/522;
428/339 |
International
Class: |
B32B 27/00 20060101
B32B027/00; B32B 9/00 20060101 B32B009/00; B32B 5/00 20060101
B32B005/00; B32B 27/30 20060101 B32B027/30; B32B 3/30 20060101
B32B003/30; B32B 27/28 20060101 B32B027/28; B32B 27/40 20060101
B32B027/40 |
Claims
1. An optical device comprising a first optical member, a second
optical member, and an antistatic layer disposed between said first
optical member and said second optical member wherein said
antistatic layer comprises the reaction product of a mixture
comprising at least one polymerizable onium salt having an anion
and at least one non-onium polymerizable monomer, oligomer, or
polymer.
2. The optical device of claim 1 wherein the onium salt is a
quaternary ammonium salt.
3. The optical device of claim 1 wherein the anion is a
fluorochemical anion.
4. The optical device of claim 3 wherein the fluoroorganic anion is
an imide.
5. The optical device of claim 3 wherein the fluoroorganic anion is
a methide.
6. The optical device of claim 1 wherein said onium salt is
selected from the group consisting of ammonium salts, sulfonium
salts, phosphonium salts, pyridinium salts, and imadazolium
salts.
7. The optical construction of claim 1 wherein said onium salt has
the formula:
(R.sup.1).sub.a-bG.sup.+[(CH.sub.2).sub.qDR.sup.2].sub.bX.sup.- (I)
wherein each R.sup.1 comprises independently an alkyl, alicyclic,
aryl, alkalicyclic, alkaryl, alicyclicalkyl, aralicyclic, or
alicyclicaryl moiety, wherein such moieties may comprises one or
more heteroatoms such as for example, nitrogen, oxygen, or sulfur,
or may comprise phosphorus, or a halogen; R.sup.1 may be cyclic or
aromatic and include G.sup.+ in the cycle, G is nitrogen, sulfur or
phosphorous; a is 3 where G is sulfur and a is 4 where G is
nitrogen or phosphorous then; b is an integer of 1 to 3 where G is
sulfur and b is an integer of 1 to 4 where G is nitrogen or
phosphorous; q is an integer from 1 to 4; D is oxygen, sulfur, or
NR wherein R is H or a lower alkyl of 1 to 4 carbon atoms; R.sup.2
is a (meth)acryl; and X.sup.- is an anion.
8. The optical device of claim 1 wherein said polymerizable
monomer, oligomer, or polymer is independently selected from the
group consisting of mono-(meth)acrylate monomers bearing
ethyleneoxy moieties, and polyurethane multi-acrylates.
9. The optical device of claim 8 wherein the acrylate or
methacrylate is alkoxylated.
10. The optical device of claim 8 wherein the acrylate or
methacrylate is ethoxylated.
11. The optical device of claim 1 wherein the at least one
non-onium polymerizable monomer, oligomer, or polymer comprises a
mixture of at least two polymerizable compounds.
12. The optical device of claim 1 wherein the at least one
non-onium polymerizable monomer, oligomer, or polymer comprises an
acrylate or a methacrylate.
13. The optical device of claim 1 wherein the at least one
non-onium polymerizable monomer, oligomer, or polymer comprises a
monofunctionally polymerizable monomer or oligomer.
14. The optical device of claim 1 wherein the at least one
non-onium polymerizable monomer, oligomer, or polymer comprises a
di- or multi-functionally polymerizable monomer or oligomer.
15. The optical device of claim 1 wherein the at least one
non-onium polymerizable monomer, oligomer, or polymer comprises a
monofunctionally polymerizable monomer or oligomer and a di- or
multi-functionally polymerizable monomer or oligomer.
16. The optical device of claim 1 wherein the at least one
non-onium polymerizable monomer, oligomer, or polymer comprises a
mixture of an aliphatic urethane diacrylate and an ethoxylated
phenoxy ethyl acrylate.
17. The optical device of claim 1 wherein the at least one
polymerizable onium salt comprises from 2 to 50% by weight of the
mixture.
18. The optical device of claim 1 wherein the mixture further
comprises a photoinitiator.
19. The optical device of claim 1 wherein the glass transition
temperature of the antistatic layer is less than 40.degree. C.
20. The optical device of claim 1 wherein the antistatic layer is
affixed to at least one of the first optical member and the second
optical member.
21. The optical device of claim 1 wherein the antistatic layer is
affixed to both the first optical member and the second optical
member.
22. The optical device of claim 1 wherein the antistatic layer is
affixed to at least one of the first optical member and the second
optical member via an intervening layer.
23. The optical device of claim 22 wherein the antistatic layer is
affixed to both the first optical member via an intervening layer,
and the second optical member via an intervening layer.
24. The optical device of claim 1 wherein the antistatic layer is
affixed to either the first optical member or the second optical
member, and is also affixed to the remaining optical member via an
intervening layer.
25. The optical device of claim 1 exhibiting a charge decay time of
less than 10 seconds.
26. The optical device of claim 1 exhibiting a charge decay time of
less than 5 seconds.
27. The optical device of claim 1 exhibiting a charge decay time of
less than 2 seconds.
28. The optical device of claim 1 wherein the first optical member
and the second optical member are independently selected from the
group consisting of optical base films, multilayer optical films,
diffuse reflecting polarizer films, prismatic brightness
enhancement films, arrays of prismatic optical features, arrays of
lenticular optical features, and beaded gain diffuser films.
29. The optical device of claim 1 wherein the first optical member
comprises an optical base film and the second optical member
comprises a prismatic brightness enhancement film.
30. The optical device of claim 29 having an Optical Gain greater
than 1.6
31. The optical device of claim 28 wherein the first optical member
comprises an optical base film and the second optical member
comprises an array of prismatic optical features.
32. The optical device of claim 28 wherein the first optical member
comprises a multilayer optical film and the second optical member
comprises a prismatic brightness enhancement film.
33. The optical device of claim 28 wherein the multilayer optical
film is a polarizer.
34. The optical device of claim 28 wherein the first optical member
comprises a multilayer optical film and the second optical member
comprises an array of prismatic optical features.
35. The optical device of claim 34 having an Optical Gain greater
than 2.0.
36. The optical device of claim 1 wherein the antistatic layer has
a surface texture on one or both sides.
37. The optical device of claim 1 wherein the antistatic layer is
greater than 0.25 micron thick.
38. The optical device of claim 1 wherein the antistatic layer is
greater than 0.5 micron thick.
39. The optical device of claim 1 wherein the antistatic layer is
greater than 1 micron thick.
40. The optical device of claim 1 wherein the charge decay time is
lower than that for an optical device which lacks said second
optical member but is otherwise identical in all respects.
41. The optical device of claim 1 wherein the charge decay time is
lower than that for an optical device which lacks said antistatic
layer but is otherwise identical in all respects.
Description
FIELD OF INVENTION
[0001] The present invention relates to optical devices exhibiting
excellent antistatic properties and optical performance.
BACKGROUND
[0002] Various optical devices employing structured surface films,
microsphere layers, or multilayer optical constructions to manage
and alter light transmission are known.
[0003] Such devices are commonly used as or in assemblies to
increase the sharpness of images produced by displays and to reduce
the power consumption necessary to produce a selected brightness.
Such assemblies are commonly used in such equipment as computers,
televisions, video recorders, mobile communication devices, and
vehicle instrument displays, etc.
[0004] Illustrative examples of brightness enhancement films and
optical assemblies comprising such films are disclosed in U.S. Pat.
Nos. 5,161,041 (Abileah), 5,771,328 (Wortman et al.), 5,828,488
(Ouderkirk et al.), 5,919,551 (Cobb et al.), 6,277,471 (Tang),
6,280,063 (Fong), 6,354,709 (Campbell et al), 6,581,286 (Campbell
et al.), 6,759,113 (Tang), 7,269,327 (Tang), and 7,269,328
(Tang).
[0005] Optical assemblies are typically assembled by laminating or
joining in desired arrangement two or more layers or films that
were separately acquired or manufactured. In the course of handling
and joining such films, e.g., removing temporary liners, packaging,
placing in desired position, etc. static electrical charges may be
created. Such charges may interfere with handling properties of the
films, e.g., causing them to undesirably cling together, cause dirt
to be entrapped in the construction, etc. Accordingly, it is
typically desirable to take steps to prevent the creation and
buildup of static electricity in the optical construction.
[0006] For example, it has been known to deposit thin film metal
layers on optical films. However, it is difficult to provide the
necessary metal film on complex surfaces (e.g., many optical film
constructions having surfaces made up of concave and convex
features) and to do so without undesirably impairing optical
performance of the construction and depending upon the construction
such films may undesirably impact optical properties of the
assembly. U.S. Pat. No. 6,577,358 (Arakawa et al.) discloses the
incorporation of a resin layer containing conductive fine particles
in an optical construction. The conductive particles in such
constructions are likely to impart haze, thereby impairing the
optical performance of the construction.
[0007] The need exists for improved constructions that exhibit
excellent antistatic properties and optical performance
SUMMARY OF INVENTION
[0008] The present invention provides novel optical devices
incorporating layers exhibiting exceptional antistatic
performance.
[0009] In brief summary, a typical embodiment of the present
invention is an optical device comprising a first optical member, a
second optical member, and an antistatic layer disposed between the
first optical member and the second optical member wherein the
antistatic layer comprises the reaction product of a mixture
comprising at least one polymerizable onium salt and at least one
non-onium polymerizable monomer, oligomer, or polymer. The
antistatic layer is disposed intermediate to the two optical
members within the optical path of the device. In some embodiments,
the antistatic layer may be affixed to either or both of the
optical members. In such embodiments, the antistatic layer may be
affixed directly to the optical member(s) or may be affixed through
an intervening layer. In other embodiments, the antistatic layer is
not in direct contact with either optical member.
[0010] Optical devices of the invention can exhibit a surprising
combination of performance including excellent optical performance,
e.g., high optical gain, and good antistatic performance evidenced
by low static decay times. The invention permits selection and use
of a variety of optical members and facilitates easy assembly
permitting convenient, cost effective assembly of optical devices
configured for desired optical performance.
BRIEF DESCRIPTION OF THE DRAWING
[0011] The invention is further explained with reference to the
drawing wherein:
[0012] FIG. 1 is a schematic illustration of an illustrative
embodiment of the invention;
[0013] FIG. 2 is a schematic cross sectional illustration of
another illustrative embodiment of the invention; and
[0014] FIG. 3 is a schematic cross sectional illustration of still
another illustrative embodiment of the invention.
[0015] These figures are not to scale and are intended to be merely
illustrative and non-limiting.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0016] All amounts are expressed in wt. % unless otherwise
indicated. All numerical quantities expressed herein are understood
to be preceded by the modifier "about" or "approximately". The
optical devices of this invention are static dissipative and will
dissipate in less than 10 seconds 90% of an electrostatic charge
applied to the front surface of the device under an applied voltage
of 5 kilovolts, preferably in less then 5 sec, more preferably in
less than 2 sec, even more preferably in less than 1 sec, and most
preferably in less than 0.1 sec. The test used is described in the
Test Methods section.
[0017] "Optical path" refers to the path in which light incident to
the front surface of the device is reflected, refracted,
transmitted, or otherwise passes through the members of the optical
device. As used herein, front refers to the surface of the optical
device or component member thereof which in use is presented for
incidence of light thereto for desired light management.
[0018] In view of this strong static dissipative performance and
the other advantageous properties of the antistatic layer, the
invention can be used to make a variety of optical devices.
[0019] "Optical Gain" of an optical device or optical stack is
defined as the ratio of the axial output luminance of an optical or
display system with the optical stack to the axial output luminance
of the same optical or display system without the optical
stack.
Optical Devices
[0020] Optical constructions of the present invention typically
comprise a first optical member, a second optical member, and an
antistatic layer disposed between the first optical member and the
second optical member within the optical path of the device wherein
the antistatic layer comprises at least one polymerizable onium
salt having a fluoroorganic anion and at least one non-onium
polymerizable monomer, oligomer, or polymer.
[0021] Depending upon the embodiment, (1) the first optical member,
second optical member, and antistatic layer may be disposed in
direct contact with one another (or with intervening connecting
layers such as adhesives, etc.), (2) the antistatic layer may be in
direct contact to either the first optical member or the second
optical member (or with intervening connecting layers such as
adhesives, etc.) and disposed some defined distance away from the
other, or (3) there may be a defined distance or gap between the
antistatic layer and the first optical member and between the
antistatic layer and the second optical member.
[0022] A schematic of an illustrative embodiment of the invention
is shown in FIG. 1 wherein optical device 10 comprises first
optical member 12, second optical member 14, and antistatic layer
16 therebetween. In this embodiment, antistatic layer 16 is in
direct contact with both first optical member 12 and second optical
member 14. In intended use, light as shown by ray 18 will be
incident to front surface 20 whereupon it will be manipulated as
desired by optical device 10.
[0023] A schematic illustration of another illustrative embodiment
of the invention is shown in FIG. 2 wherein optical device 210
comprises first optical member 212, second optical member 214 and
antistatic layer 216 which is adhered to back surface 222 of first
optical member 212 by optional adhesive layer 224. Device 210
further comprises optional frame 226 which supports first optical
member 212 and second optical member 214 in desired optically
effective arrangement to achieve desired optical performance.
[0024] A schematic illustration of still another illustrative
embodiment of the invention is shown in FIG. 3 wherein optical
device 310 comprises first optical member 312, second optical
member 314, and intermediately thereto without contact to either
optical member antistatic layer 316 which are supported in desired
optically effective arrangement by optional frame 326.
[0025] Those skilled in the art will be able to readily select
suitable adhesives, if any, frame components, if any, and other
components of the optical device in accordance with the present
invention.
[0026] Optical members for use in optical devices of the present
invention can be readily selected by those skilled in the art,
dependent in part upon the optical performance desired of the
resultant device. Optical films used herein could be monolayer
members, e.g., substantially flat sheet of polyester sometimes
referred to as a polyester base film, or multilayer assemblies
comprising intricately formed component features that provide more
specialized optical performance. For example, the first optical
member and the second optical member may be independently selected
from the group consisting of optical base films, multilayer optical
films, diffuse reflecting polarizer films, prismatic brightness
enhancement films, arrays of prismatic optical features, arrays of
lenticular optical features, and beaded gain diffuser films.
[0027] In some embodiments, one or both of the optical members will
be individually selected from the group consisting of reflective
polarizers (e.g., so-called multilayer optical films or "MOFs"
having regularly repeating layers of alternating refractive
indices), brightness enhancement films, and diffuse reflecting
polarizer films (sometimes referred to as "DRPFs" having multiphase
structures with domains of differing refractive indices). One
illustrative example of a reflective polarizer is VIKUITI.TM. Dual
Brightness Enhancement Film II (DBEF-II), commercially available
from 3M Company, St. Paul Minn., and described in U.S. Pat. No.
7,345,137 (Hebrink et al.). Suitable prismatic brightness
enhancement films (sometimes referred to as "BEFs"), also
commercially available from 3M, are described in, e.g., U.S. Pat.
Nos. 5,771,328 (Wortman et al.), 6,280,063 (Fong), and 6,354,709
(Campbell et al.) and U.S. Patent Appln. Publn. No. 20090017256
(Hunt et al.). Illustrative examples of diffuse reflecting
polarizer films that can be used as optical members herein include
those disclosed in U.S. Pat. No. 5,825,543 (Ouderkirk et al.).
Illustrative examples of commercially available optical films
suitable for use herein include VIKUITI.TM. Dual Brightness
Enhanced Film (DBEF), VIKUITI.TM. Brightness Enhanced Film (BEF),
VIKUITI.TM. Diffuse Reflective Polarizer Film (DRPF), VIKUITI.TM.
Enhanced Specular Reflector (ESR), and VIKUITI.TM. Advanced
Polarizing Film (APF), all available from 3M Company.
[0028] As described in U.S. Pat. Nos. 5,175,030 and 5,183,597 (both
Lu et al.), a microstructure-bearing article (e.g. brightness
enhancing film) can be prepared by a method including the steps of
(a) preparing a polymerizable composition; (b) depositing the
polymerizable composition onto a master negative microstructured
molding surface in an amount barely sufficient to fill the cavities
of the master; (c) filling the cavities by moving a bead of the
polymerizable composition between a preformed base (such as a PET
film) and the master, at least one of which is flexible; and (d)
curing the composition. The master can be metallic, such as nickel,
nickel-plated copper or brass, or can be a thermoplastic material
that is stable under the polymerization conditions, and that
preferably has a surface energy that allows clean removal of the
polymerized material from the master.
[0029] Useful base materials include, for example,
styrene-acrylonitrile, cellulose acetate butyrate, cellulose
acetate propionate, cellulose triacetate, polyether sulfone,
polymethyl methacrylate, polyurethane, polyester, polycarbonate,
polyvinyl chloride, polystyrene, polyethylene naphthalate,
copolymers or blends based on naphthalene dicarboxylic acids,
polycyclo-olefins, polyimides, and glass. Optionally, the base
material can contain mixtures or combinations of these materials.
Further, the base may be multi-layered or may contain a dispersed
component suspended or dispersed in a continuous phase.
[0030] For some microstructure-bearing products such as brightness
enhancement films, examples of preferred base materials include
polyethylene terephthalate (PET) and polycarbonate. Examples of
useful PET films include photograde polyethylene terephthalate and
MELINEX.TM. PET available from DuPont Teijin Films of Hopewell,
Va.
[0031] Some base materials can be optically active, and can act as
polarizing materials. Polarization of light through a film can be
accomplished, for example, by the inclusion of dichroic polarizers
in a film material that selectively absorb passing light. Light
polarization can also be achieved by including inorganic materials
such as aligned mica chips or by a discontinuous phase dispersed
within a continuous film, such as droplets of light modulating
liquid crystals dispersed within a continuous film. As an
alternative, a polarizing film can be prepared from microfine
layers of different materials. The materials within the film can be
aligned into a polarizing orientation, for example, by employing
methods such as stretching the film, applying electric or magnetic
fields, and coating techniques.
[0032] Examples of polarizing films include those described in U.S.
Pat. Nos. 5,825,543 and 5,783,120 (both Ouderkirk et al.). The use
of these polarizer films in combination with a brightness
enhancement film has been described in U.S. Pat. No. 6,111,696
(Allen et al.). Other examples of polarizing films that can be used
as a base are those films described in U.S. Pat. No. 5,882,774
(Jonza et al.).
[0033] Useful substrates include commercially available optical
films marketed as VIKUITI.TM. Dual Brightness Enhancement Film
(DBEF), VIKUITI.TM. Brightness Enhancement Film (BEF), VIKUITI.TM.
Diffuse Reflective Polarizer Film (DRPF), VIKUITI.TM. Enhanced
Specular Reflector (ESR), and VIKUITI.TM. Advanced Polarizing Film
(APF), all available from 3M Company.
[0034] One or more of the surfaces of the base film material can
optionally be primed or otherwise be treated to promote adhesion of
the optical member to the base. Primers particularly suitable for
polyester base film layers include sulfopolyester primers, such as
described in U.S. Pat. No. 5,427,835 (Morrison et al.). The
thickness of the primer layer is typically at least 20 nm and
generally no greater than 300 nm to 400 nm.
[0035] The optical member can have any of a number of useful
patterns. These include regular or irregular prismatic patterns,
which can be an annular prismatic pattern, a cube-corner pattern or
any other lenticular microstructure. A useful microstructure is a
regular prismatic pattern that can act as a totally internal
reflecting film for use as a brightness enhancement film. Another
useful microstructure is a corner-cube prismatic pattern that can
act as a retro-reflecting film or element for use as reflecting
film. Another useful microstructure is a prismatic pattern that can
act as an optical turning film or element for use in an optical
display.
[0036] One preferred optical film having a polymerized
microstructured surface is a brightness enhancing film. Brightness
enhancing films generally enhance on-axis luminance (referred
herein as "brightness") of a lighting device. The microstructured
topography can be a plurality of prisms on the film surface such
that the films can be used to redirect light through reflection and
refraction. The height of the prisms typically ranges from 1 to 75
microns though features outside this range may, of course, be used.
When used in an optical display such as that found in laptop
computers, watches, etc., the microstructured optical film can
increase brightness of an optical display by limiting light
escaping from the display to within a pair of planes disposed at
desired angles from a normal axis running through the optical
display. As a result, light that would exit the display outside of
the allowable range is reflected back into the display where a
portion of it can be "recycled" and returned back to the
microstructured film at an angle that allows it to escape from the
display. The recycling is useful because it can reduce power
consumption needed to provide a display with a desired level of
brightness.
[0037] The microstructured optical member of a brightness enhancing
film generally comprises a plurality of parallel longitudinal
ridges extending along a length or width of the film. These ridges
can be formed from a plurality of prism apexes. Each prism has a
first facet and a second facet. The prisms are formed on a base
that has a first surface on which the prisms are formed and a
second surface that is substantially flat or planar and opposite
the first surface. By right prisms it is meant that the apex angle
is typically 90.degree.. However, this angle can range from
70.degree. to 120.degree. and may range from 80.degree. to
100.degree.. These apexes can be sharp, rounded or flattened or
truncated. For example, the ridges can be rounded to a radius in a
range of 4 to 7 to 15 micrometers. The spacing between prism peaks
(or pitch) can be 5 to 300 microns. The prisms can be arranged in
various patterns such as described in U.S. Pat. No. 7,074,463
(Jones et al.).
[0038] The pitch of the structures of a brightness enhancing film
is typically preferably 1 millimeter or less, more preferably from
10 microns to 100 microns, and still more preferably from 24
microns to 50 microns. A pitch of 50 microns has been found to work
quite well. The preferred pitch will depend, in part, on the pixel
pitch of a liquid crystal display or the parameters of some other
optical application of the film. The prism pitch should be chosen
to help minimize moire interference.
[0039] In optical devices of the invention using thin brightness
enhancing films, the pitch is preferably 10 to 36 microns, and more
preferably 17 to 24 microns. This corresponds to prism heights of
preferably 5 to 18 microns, and more preferably 9 to 12 microns.
The prism facets need not be identical, and the prisms may be
tilted with respect to each other. The relationship between the
total thickness of the optical article, and the height of the
prisms, may vary. However, it is typically desirable to use
relatively thinner optical members with well-defined prism facets.
For thin brightness enhancing films on substrates with thicknesses
close to 1 mil (20 to 35 microns), a typical ratio of prism height
to total thickness is generally from 0.2 to 0.4. In other
embodiments, thicker BEF materials will be used, such as BEF
materials having a 50 micron pitch and 25 micron thickness.
[0040] As will be understood by those skilled in the art, optical
devices of the invention may be made using other kinds of optical
members or other embodiments of MOF, BEF, or DRPF materials than
those illustrative examples discussed above.
[0041] The antistatic constructions described herein comprise a
polymerized reaction product of a polymerizable resin composition
comprising an antistatic agent.
[0042] Although various antistatic agents can provide static decay
times (as measured according to the test method described in the
Examples) of 2 to 10 seconds, it has been found that only certain
kinds and amounts of antistatic agents can provide static decay
times of less than 2 seconds. Preferred antistatic agents provide
static decay times of no greater than 2, 1, or 0.1 seconds.
[0043] For embodiments wherein microstructures or a microstructured
member are disposed upon the antistatic layer which is in turn
disposed upon a base layer such as a light transmissive (e.g.,
polyester) film or multilayer optical film, the kind and amount of
antistatic agent in the antistatic layer is also selected such that
the presence thereof in the polymerizable resin does not detract
from the adhesion of the polymerized antistatic layer with the base
film layer or the microstructures or microstructured member. The
entire construction so obtained exhibits a crosshatch peel adhesion
(as measured according to the test method described in the
Examples) to the base film layer of at least 80%, 85%, or 90%. In
most preferred embodiments, the crosshatch adhesion is 95 to
100%.
Antistatic Layer
[0044] The antistatic layer comprises the reaction product of at
least one polymerizable onium salt having an anion and at least one
non-onium polymerizable monomer, oligomer, or polymer.
[0045] Suitable onium salts can be selected from the group
consisting of: ammonium salts, sulfonium salts, phosphonium salts,
pyridinium salts, and imidazolium salts
[0046] A preferred onium salt for use in the present invention has
the formula:
(R.sup.1).sub.a-bG.sup.+[(CH.sub.2).sub.qDR.sup.2].sub.bX.sup.-
(I)
wherein: [0047] each R.sup.1 comprises independently an alkyl,
alicyclic, aryl, alkalicyclic, alkaryl, alicyclicalkyl,
aralicyclic, or alicyclicaryl moiety, wherein such moiety may
comprises one or more heteroatoms such as for example, nitrogen,
oxygen, or sulfur, or may comprise phosphorus, or a halogen (and
thus can be fluoroorganic in nature), R.sup.1 may be cyclic or
aromatic and may include G.sup.+ in the cycle; [0048] G is
nitrogen, sulfur or phosphorus; [0049] a is 3 where G is sulfur and
a is 4 where G is nitrogen or phosphorus then; [0050] b is an
integer of 1 to 3 where G is sulfur and b is an integer of 1 to 4
where G is nitrogen or phosphorus; [0051] q is an integer from 1 to
4; [0052] D is oxygen, sulfur, or NR wherein R is H or a lower
alkyl of 1 to 4 carbon atoms; [0053] R.sup.2 is a (meth)acryl; and
[0054] X.sup.- is an anion, preferably an organic anion, and more
preferably a fluoroorganic anion.
[0055] Throughout this disclosure, the use of "(meth)" in front of
any derivative of "acryl" will be understood to mean "acryl or
methacryl".
[0056] In some embodiments, in which G.sup.+ is included in the
cycle, the onium salt has one of the formulas:
##STR00001##
[0057] The onium salt may be present in the layer at a weight
percentage of 1 to 99%, preferably 10 to 60%, more preferably 30 to
50%. The acryl functional oniums are preferred over the methacryl
oniums because they exhibit a faster and greater degree of
cure.
[0058] Illustrative examples of anions useful herein include alkyl
sulfates, methane sulfonates, tosylates, fluoroorganics,
fluoroinorganics, and halides.
[0059] Most preferably the anion is a fluorochemical anion.
Fluoroorganic anions suitable for use herein include those
described in U.S. Pat. No. 6,924,329 (Klun et al.), column 8, lines
2 to 65. The fluoroorganic ions provide greater solubility and
compatibility of the onium salt with the non-onium polymerizable
monomers, oligomers, or polymers. This is important in providing a
layer with good clarity, and good ion mobility which can improve
the antistatic performance of the resultant layer. Some
illustrative examples include --C(SO.sub.2CF.sub.3).sub.3,
--O.sub.3SCF.sub.3, --O.sub.3SC.sub.4F.sub.9, and
--N(SO.sub.2CF.sub.3).sub.2. Due to availability and cost the
following are often preferred: --O.sub.3SCF.sub.3,
--O.sub.3SC.sub.4F.sub.9, and --N(SO.sub.2CF.sub.3).sub.2.
Typically --N(SO.sub.2CF.sub.3).sub.2 is most preferred because it
provides a broader range of solubility than some of the
alternatives, making compositions containing it somewhat easier to
prepare and use.
[0060] The non-onium polymerizerable monomers, oligomer, or
polymers are key to the performance of the optical film. They,
along with the onium salts, control key characteristics of the
antistatic optical film including the static decay of the film, its
haze and clarity, its cohesive strength, and its interlayer
adhesion.
[0061] The onium salt, polymerizable silicone and/or
perfluoropolyether content, and other components, if any, should be
compatible in that they will mix and polymerize to form transparent
films.
[0062] In some embodiments, the antistatic layer will be formed on
the optical layer by the following method: (1) providing a liquid
coating composition comprising (a) at least one polymerizable onium
salt as described herein, (b) at least one non-onium polymerizable
silicone or perfluoropolyether moiety-containing monomer, oligomer,
or polymer as described herein, and optionally (c) at least one
non-silicone, non-perfluoropolyether monomer, oligomer, or polymer;
(2) applying the liquid coating composition to the surface of an
optical layer; and (3) curing the liquid coating composition in
situ to form the antistatic layer on the surface of the optical
layer. In other embodiments, the antistatic layer will be formed on
one side of a substrate film, e.g., a polyester film, the other
side of which is subsequently positioned on the surface of an
optical film, e.g., adhered by lamination or with adhesive, or held
in place with mechanical means.
[0063] The Examples disclosed in this application provide data
correlating the T.sub.g of antistatic layers and static decay
exhibited by optical devices of the invention.
[0064] The T.sub.g of the cured antistatic layer is preferably less
than 50.degree. C., more preferably less than 40.degree. C., even
more preferably less than 30.degree. C., even more preferably less
than 20.degree. C., even more preferably less than 10.degree. C.,
and most preferably less than 0.degree. C. While not wishing to be
bound by this theory, it is believed that ionic mobility is needed
to provide desired antistatic performance.
[0065] The non-onium polymerizerable monomers, oligomers, or
polymers must be carefully chosen to be compatible with the onium
salts so as to provide for clear, homogeneous solutions that are
amenable to processing and coating. If the intended coating
formulations are significantly incompatible, then the constituents
wan stratify into two liquid phases or can also form solid
precipitates so as to render the mixtures inappropriate for
handling in a coating process and/or can yield hazy and
inhomogeneous cured coatings.
[0066] The material choices for the antistat layer affect the
adhesion of the antistat layer to the first optical member and the
second optical member in those cases where the layers are in
intimate contact. This adhesion requirement is particularly acute
in optical display films wherein the construction needs to survive
the durability requirements of the backlight industry without
adhesion failure between optical members and the interstitial
antistatic coating.
[0067] The non-onium polymizerable monomers, oligomer, or polymers
must be carefully chosen to provide a layer with sufficient
cohesive strength of the cured antistatic layer. The cohesive
strength is not only important for the durability of the finished
optical construction as described above but is also critical to the
successful coating and curing of the antistatic formulation. For
example, if the antistatic formulation of choice is cast and cured
against tooling for development of microtexture (as described
below) then the effective and comprehensive release of the cured
coating from the replication surface is strongly dependent on the
cohesive strength of the coating. This is particularly challenging
for the lower T.sub.g (mechanically softer) formulations required
for premium charge decay and attendant antistatic performance.
[0068] Useful non-onium polymizerable monomers, oligomers, or
polymers, may include, for example, poly (meth)acryl monomers
selected from the group consisting of: [0069] (a) mono(meth)acryl
containing compounds such as phenoxyethyl acrylate, ethoxylated
phenoxyethyl acrylate, 2-ethoxyethoxyethyl acrylate, ethoxylated
tetrahydrofurfural acrylate, and caprolactone acrylate; [0070] (b)
di(meth)acryl containing compounds such as 1,3-butylene glycol
diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate,
1,6-hexanediol monoacrylate monomethacrylate, ethylene glycol
diacrylate, alkoxylated aliphatic 30 diacrylate, alkoxylated
cyclohexane dimethanol diacrylate, alkoxylated hexanediol 26
diacrylate, alkoxylated neopentyl glycol diacrylate, caprolactone
modified neopentylglycol hydroxypivalate diacrylate, caprolactone
modified neopentylglycol hydroxypivalate diacrylate,
cyclohexanedimethanol diacrylate, diethylene glycol diacrylate,
dipropylene glycol diacrylate, ethoxylated (10) bisphenol A
diacrylate, ethoxylated (3) bisphenol A diacrylate, ethoxylated
(30) bisphenol A diacrylate, ethoxylated (4) bisphenol A
diacrylate, hydroxypivalaldehyde modified trimethylolpropane
diacrylate, neopentyl glycol diacrylate, polyethylene glycol (200)
diacrylate, polyethylene glycol (400) diacrylate, polyethylene
glycol (600) diacrylate, propoxylated neopentyl glycol diacrylate,
tetraethylene glycol diacrylate, tricyclodecanedimethanol
diacrylate, triethylene glycol 10 diacrylate, tripropylene glycol
diacrylate; [0071] (c) tri(meth)acryl containing compounds such
asglycerol triacrylate, trimethylolpropane triacrylate,
pentaerythritol triacrylate, ethoxylated triacrylates (e.g.,
ethoxylated (3) trimethylolpropane triacrylate, ethoxylated (6)
trimethylolpropane triacrylate, ethoxylated (9) trimethylolpropane
triacrylate, ethoxylated (20) trimethylolpropane triacrylate),
propoxylated triacrylates (e.g., propoxylated (3) glyceryl 15
triacrylate, propoxylated (5.5) glyceryl triacrylate, propoxylated
(3) trimethylolpropanetriacrylate, propoxylated (6)
trimethylolpropane triacrylate), trimethylolpropanetriacrylate,
tris(2-hydroxyethyl)isocyanurate triacrylate; [0072] (d) higher
functionality (meth)acryl containing compounds such as
pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate,
dipentaerythritol pentaacrylate, ethoxylated (4) pentaerythritol
tetraacrylate, caprolactone 20 modified dipentaerythritol
hexaacrylate; [0073] (e) oligomeric (meth)acryl compounds such as,
for example, urethane acrylates, polyester acrylates, epoxy
acrylates; polyacrylamide analogues of the foregoing; and [0074]
(f) combinations thereof. Such compounds are widely available from
vendors such as, for example, Sartomer Company, Exton,
Pennsylvania; UCB Chemicals Corporation, Smyrna, Georgia; Cytec
Corporation, Smyrna, Georgia; Cognis Performance Chemicals UK,
South Hampton, UK; and Aldrich Chemical Company, Milwaukee, Wis.
Additional useful (meth)acrylate materials include hydantoin
moiety-containing poly(meth)acrylates, for example, as described in
U.S. Pat. No. 4,262,072 (Wendling et al.).
[0075] The onium salt and polymerizable non-onium content should be
compatible in that they will mix and polymerize to form transparent
films.
[0076] In many applications, it may be beneficial to apply the
antistatic coatings of the current invention is such a way that at
least one surface of the resulting cured coating layer is not
perfectly smooth, but rather, has a microtextured surface and/or a
matte finish. In this way, the antistatic layer may also serve the
additional purpose of, for example, optically masking and/or
eliminating physical defects such as scratches, and undesirable
optical effects such as moire and color mura.
[0077] One method of producing such a surface involves forming the
antistatic layer against microstructured tooling. Illustrative
examples are disclosed PCT Application Nos. US2010/036018 (Aronson
et al.) and US2010/045118 (Yapel et al.). Microstructures which
have been machined into the tooling are replicated on the surface
of the final cured coating which has been cast against the
tooling.
[0078] Microstructures can be any type microstructures that may be
desirable in an application. In some cases, microstructures can be
recessions or depressions. In some cases, microstructures can be
protrusions. In some cases, microstructures form a regular pattern.
In some cases, microstructures form an irregular pattern. In some
cases, microstructures form a pseudo-random pattern that appears to
be random. In general, microstructures can have any height and any
height distribution.
[0079] As disclosed in PCT Application Nos. US2010/036018 and
US2010/045118, certain advantages useful in a given application can
be obtained by controlling the fraction of the textured surface
having a slope magnitude greater than some threshold size, and/or
controlling the microstructures such that they have a slope
distribution having a half width at half maximum (HWHM) that is not
greater than some threshold value, or whose value lies in some
preferred range.
[0080] Another method of producing such a surface involves forming
the antistatic layer against tooling that has been subjected to
electrodeposition of metal to form a fine structure on the tooling,
as taught in PCT Application No. WO2009/079275 (Aronson et al.).
The tooling may or may not have a microstructure of some kind
already machined upon it prior to the electrodeposition. This
deposition process creates raised areas on the tooling, which in
turn create recesses in a cured coating that had been cast against
the tooling.
[0081] The shapes and sizes of the recesses vary depending upon the
type of metal that is electroplated onto a roll mold. The shapes
and sizes of the recesses are the reverse of the shapes and sizes
of the metal structures plated onto the roll. Such shapes include
those that resemble pores, semi-hemispheres, "jagged" valleys,
"craters," and the surface of cauliflower. Recesses may overlap, be
within one another, or be isolated from one another. The size, that
is, largest diameter, of the recesses can range from 0.5
micrometers to 125 micrometers at their largest diameter. A typical
range is from 0.5 to 15 micrometers. Areas of the recesses can
range from 0.01 to 1100 square micrometers. Depths can range from
0.2 to 20 micrometers.
[0082] In order to form the recesses on the microstructured
surface, in one embodiment, a microstructured roll is subjected to
an electroplating process. Metal accretes inhomogeneously on the
microstructured surface of the roll, forming protuberances. The
microstructured surface of the optical film replicates with pores
or pits, etc., relative to the microstructured surface of the roll.
The size and density of the metal structures deposited onto the
microstructured roll via the electroplating process is determined
by the current density, the roll face speed, and the plating time.
The type of metal salt used in the electroplating process
determines the geometry of the deposited metal structures, and
thus, determines the shape of the recesses on the microstructured
surface. The location and disposition of the deposited metal
structures on the microstructured roll is random.
[0083] Yet another method of producing such a surface involves
manipulating the process of curing the coating, after it has been
applied smooth, in such a way that texture can be simply imposed
upon the coating and cured in place, as taught in US Patent Appln.
Publn. No. 2009/0029054 (Yapel et al.).
[0084] A coated substrate comprising a coatable material disposed
on a substrate is treated in such a way as to change the viscosity
of the coatable material from the initial viscosity to a second
viscosity, and then the surface of the coating is contacted with at
least one face-side roller to impart a matte finish and the
coatable material is optionally further hardened to provide the
finished coating film.
[0085] A coatable material is applied to (e.g., coated on) a
substrate to provide the coated substrate. Coatable material is
carried on the substrate and is treated to change the viscosity of
the coatable material from a first or initial viscosity to a second
viscosity. In some embodiments, the first viscosity is lower than
the second viscosity so that the coatable material is changed by
being thickened or partially cured. In some embodiments, the
coatable material may have an initial viscosity that is higher than
the second viscosity so that changing the viscosity of the coatable
material may require at least some softening of the coatable
material. Once the viscosity of the coatable material is at a
second viscosity, the material is then subjected to face-side
pressure to impart a matte finish thereon. With its matte finish,
the coatable material may optionally be further hardened, cured or
solidified and the resulting film may be conveyed to another
processing station such as a cutting station, or to a wind-up roll,
for example. Expensive tooling is not required to impart a matte
finish.
[0086] Yet another method of producing such a surface involves the
inclusion of beads in the coating as applied to its substrate. A
multiphase coating can have a matte surface structure generated
from immiscible materials incorporated in the coating at the
surface or within the bulk of the coating, e.g., entrainment of
particles such as polymethyl methacrylate beads in the coating. In
some embodiments, particles with different refractive index from
the bulk of the coating can be used to impart desired haze
properties without necessarily yielding a matte surface. Though
useful particles can be of any shape, typically preferred particle
shapes are often in the form of spherical or oblong beads.
Preferable particle sizes are generally 0.1 microns to 20 microns
average diameter. Particles can be made from any material that is
compatible with the coating. Some illustrative examples of suitable
materials for particles include polymethylmethacrylate,
polybutylmethacrylate, polystyrene, polyurethane, polyamide,
polysilicone, and silica. Useful particles can be obtained from
Ganz Chemical, Sekisui Plastics Co., Ltd., and Soken Chemical &
Engineering Co., Ltd, all of Japan.
[0087] These methods of providing surface microtexture or matte
finish to an antistatic layer, can be particularly effective in
reducing color mura or color banding in optical devices. This is
especially true when the antistatic layer bearing the
microstructured surface or matte finish is subsequently overcoated
with another optical film, especially a microprismatic layer.
[0088] US Patent Appln. Publn. No. 2007/0115407 (Richard et al.)
discusses the issue of color banding and the role of optical
diffusion, such as can be provided by a microstructured surface or
matte finish on the cured antistatic layer of the present
invention, in removing color banding.
EXAMPLES
[0089] The invention will be further explained with reference to
the following examples wherein amounts are expressed in parts by
weight unless otherwise indicated.
Test Methods
[0090] The following methods were used in the examples.
[0091] Charge Decay for Antistatic Performance
[0092] Average static decay was determined for film samples using
the following method. Sheets of test materials were cut into 12 cm
by 15 cm samples and conditioned at relative humidity ("RH") of 44%
to 50% at nominal room temperature ("RT") of 23.degree. C. to
27.degree. C. for at least 12 hours. The static charge dissipation
time was measured under the same conditions of temperature and
humidity as used for the 12 hour preconditioning according to
MIL-STD 3010, Method 4046, formerly known as the Federal Test
Method Standard 10113, Method 4046, "Antistatic Properties of
Materials", using an ETS.TM. Model 406D Static Decay Test Unit
(manufactured by Electro-Tech Systems, Inc., Glenside, Pa.). This
apparatus was used to induce an initial static charge (Average
Induced Electrostatic Charge) on the surface of the flat test
material by using high voltage (5000 volts), and a field meter was
used to observe the charge decay. The actual charge induced by the
imposition of the 5000 volt induction was noted. Then the time
required for the charge to decay to 10 percent of the initial
induced charge was recorded. This is the static charge dissipation
time. The lower the static charge dissipation time, the better are
the antistatic properties of the test material. All reported values
of the static charge dissipation times in this specification were
determined by taking the average of at least 6 separate
determinations (Average Charge Decay). At least three of these
determinations were measured using a positive +5 KV applied charge
and at least three of these determinations were measured using a
negative -5 KV applied charge. When a sample being tested did not
accept a charge of at least 80% of the imposed 5 KV potential
(i.e., 4000 volts) it was deemed not to be antistatic and assigned
the designation of "wnc" (would not charge).
[0093] Differential Scanning Calorimetric Determination of Glass
Transition Temperature
[0094] The glass transition temperatures (T.sub.g) for cured
specimens of antistatic coating formulations were determined using
a model Q100 Differential Scanning calorimeter (manufactured by TA
Instruments, Inc., New Castle, Del.). 20 milligrams of cured
coating material was charged into standard DSC sample pans and the
pans were crimped to close. Specimens, as loaded into crimped pans,
were delivered into the measurement cell of the Q100 instrument,
and the thermogram was recorded under a modulated temperature scan
protocol described as follows: Initially, the specimen was cooled
quickly to -50.degree. C. and held under isothermal conditions for
5 minutes to stabilize heat flow. Subsequently, the sample was
scanned at an overall heating rate of 2.5.degree. C./min, with
superimposed modulation amplitude of 0.5.degree. C. and modulation
period of 60 seconds, to a final temperature of 100.degree. C. The
reversible component of heat flow was recorded by the instrument
and analyzed using software provided by TA Instruments to determine
the T.sub.g as the midpoint of the characteristic inflection
associated with the glass transition as seen in reversible heat
flow thermograms.
[0095] Cross Hatch Peel ("CHP") Measurement for Adhesion
[0096] Adhesion of the BEF prism coat and antistatic under coat to
a base film were determined using ASTM D3359-02, with minor
modifications as detailed here. First, the specimen coatings were
scored in a selected test area with a cross hatch pattern. Next,
adhesive tape was adhered to the test area. Finally, the tape was
peeled from the test area in a prescribed manner. The adhesion was
evaluated based upon the extent of removal of cross hatch scored
coating from the specimen. The device for scoring the specimen had
6 sharp scoring blades arranged in parallel array with equal
blade-to-blade spacing of approximately 1 mm. The scoring device
was dragged across the test area with an applied load of 1000
grams. This force was chosen as adequate to penetrate the two
stacked coatings such that each blade penetrated at least to the
surface of the film underlying the coatings, and possibly slightly
beyond and into the film. The six lanes of score were applied to a
length of 2 to 3 inches (5 to 7.5 cm) at an angle of 45 degrees to
the BEF prism axis. Scoring to similar length was then performed
approximately orthogonally to the first scoring direction to form a
cross hatch such that the second scoring was at an angle of (-)45
degrees to the BEF prism axis. This provided a 5 by 5 array of
scored squares at a final cross hatch area of 25 mm.sup.2. One
diagonal of the cross hatch square lay parallel to the BEF prism
axis. A piece of 3M.TM. #610 tape (a cellophane tape with a high
tack, rubber resin adhesive) was then applied by hand to the test
area such that the long axis of the tape was coincident with the
BEF prism axis. The tape was pressed firmly onto the test specimen
using firm hand pressure with a soft plastic squeegee. The test
specimen was then allowed to relax undisturbed for three to four
minutes to allow the adhesion to build to a steady state. The tape
was then removed by hand as quickly and aggressively as possible,
such that the tape end was pulled straight up in the direction
normal to the coated surface. The evaluation of adhesion was based
on how much of the cross hatched area was removed (transferred to
tape adhesive) after the tape peel according to the following
ranking system:
TABLE-US-00001 Rank % Area Removed 0 0 to 5 1 5 to 50 2 50 to 95 3
95 to 100
[0097] In this test protocol the cross hatch adhesion was measured
four times on a given material and performance was reported as an
average of the rankings determined for each of the four peel tests.
The same operator performed all cross hatch peel adhesion tests
reported herein, so as to eliminate the possibility of operator
variability.
Materials
[0098] The following commercial products and materials were used in
the Examples and Comparative Examples: [0099] CD 9087
(monofunctional acrylate): ethoxylated (3) phenol acrylate from
Sartomer Company, Inc. (Exton, Pa.); [0100] CD 9088 (monofunctional
acrylate): ethoxylated (6) phenol acrylate from Sartomer Company,
Inc.; [0101] EBECRYL.TM. 110 (monofunctional acrylate): ethoxylated
(2) phenol acrylate from Cytec Surface Specialties Inc. (Smyrna,
Ga.); [0102] EBECRYL.TM. 8402 (multifunctional acrylate): aliphatic
urethane diacrylate from Cytec Surface Specialties Inc.; [0103]
IRGACURE.TM. 819 photoinitiator from Ciba Specialty Chemicals, now
a part of BASF Group (Florham Park, N.J.); [0104] SR 339
(monofunctional acrylate): 2-phenoxy ethyl acrylate from Sartomer
Company, Inc.; [0105] SR 494 (multifunctional acrylate):
ethoxylated (4) pentaerythritol tetraacrylate from Sartomer
Company, Inc.; [0106] SR 9035 (multifunctional acrylate):
ethoxylated trimethylolpropane triacrylate from Sartomer Company,
Inc.; [0107] AGEFLEX.TM. FA1Q80MC*500
(N-acryloyloxyethyl-N,N,N-trimethylammonium chloride,
(CH.sub.3).sub.3NCH.sub.2CH.sub.2OC(O)CH.dbd.CH.sub.2.sup.+Cl.s-
up.-) at 80% solids in water, from Ciba, Suffolk, Va.; [0108]
AGEFLEX.TM. FM2*PTZ (N-methacryloyloxyethyl-N,N-diethyl amine,
(CH.sub.3CH.sub.2).sub.2NCH.sub.2CH.sub.2OC(O)C(CH.sub.3).dbd.CH.sub.2),
from Ciba; [0109] AGEFLEX.TM. FA 1 (dimethylaminoethyl acrylate)
from CIBA; 3M.TM. FLUORAD.TM. HQ-115 (lithium
bis(trifluoromethanesulfonyl)imide,
Li.sup.+-N(SO.sub.2CF.sub.3).sub.2): from 3M Company; [0110]
lithium nonafluorobutanesulfonate from 3M; [0111] lithium
trifluoromethanesulfonate from 3M; [0112]
tris(trifluoromethanesulfonyl)methane, HC(SO.sub.2CF.sub.3).sub.3
from DayChem Laboratories, Vandalia, Ohio; [0113] lithium hydroxide
monohydrate from J. T. Baker; [0114] 1-bromohexadecane from
Aldrich; [0115] BHT (i.e., 2,6-di-tert-butyl-4 methyl phenol),
dimethyl sulfate, hexadecyl bromide, N-(hydroxyethyl)-N,N-diethyl
amine (CH.sub.3CH.sub.2).sub.2NCH.sub.2CH.sub.2OH),
N-(hydroxyethyl)-N,N-dibutyl amine,
(CH.sub.3CH.sub.2CH.sub.2CH.sub.2).sub.2NCH.sub.2CH.sub.2OH),
phenothiazine, methoxy hydroquinone (MEHQ), and acryloyl chloride
from Sigma-Aldrich, Milwaukee, Wis.; and [0116] triethylamine,
methyl t-butyl ether ("MTBE"), acetone, anhydrous magnesium
sulfate, and dichloromethane from EMD Chemicals, Gibbstown,
N.J.
[0117] The various polymerizable onium materials used in the
examples were prepared as follows.
Preparation of
(CH.sub.3).sub.3NCH.sub.2CH.sub.2OC(O)CH.dbd.CH.sub.2.sup.+-N(SO.sub.2CF.-
sub.3).sub.2; acryloyloxyethyl-N,N,N-trimethylammonium
bis(trifluoromethanesulfonyl)imide (Referred to Herein as
POS-1)
[0118] A tared 5 L, 3-necked round bottom flask equipped with
overhead stirrer was charged with 148 6 g (79.1% solids in water,
6.069 mol) AGEFLEX.TM. FA1Q80MC*500 and the contents were heated to
40.degree. C. To the flask was added over one minute 2177.33 g (80%
solids in water, 6.069 mol) HQ-115, followed by 597.6 g deionized
water. After stirring for 1 hour, the reaction was transferred to a
separatory funnel and the lower organic layer (2688.7 g) was
returned to the reaction flask and washed with 1486 g deionized
water at 40.degree. C. for 30 min. The lower layer (2656.5 g) was
again separated from the aqueous layer and placed in a dry 5 L,
3-necked round bottom equipped with overhead stirrer and stillhead,
and air bubbler. To the flask was added 2000 g acetone and the
reaction was distilled at atmospheric pressure over 6 hour with an
air sparge to azeotropically dry the product, yielding 2591 g of a
clear liquid which slowly crystallized to a solid.
Preparation of
(CH.sub.3CH.sub.2).sub.2N(CH.sub.3)CH.sub.2CH.sub.2OC(O)CH.dbd.CH.sub.2.s-
up.+-N(SO.sub.2CF.sub.3).sub.2;
acryloyloxyethyl-N,N-diethyl-N-methylammonium
bis(trifluoromethanesulfonyl)imide (Referred to Herein as
POS-2)
[0119] A 5 L, 3-necked roundbottom flask equipped with overhead
stirrer was charged with 500 g (4.24 mol)
N-(hydroxyethyl)-N,N-diethyl amine, 1329 g of t-butyl methyl ether
and 0.046 g phenothiazine and cooled in an isopropanol-water-dry
ice bath to -4.degree. C. Next, via two dropping funnels, were
added simultaneously, at approximately equimolar rates, 422.23 g
(4.67 mol) acryloyl chloride and 407.12 g (5.09 mol) of 50% solids
sodium hydroxide in water, over 3 hours, during which time 418 g
additional t-butyl methyl ether was added. After 3 hours, the
reaction was diluted with 1329 g of t-butyl methyl ether, and
washed with 443 g water containing 25.47 g (0.424 mol) acetic acid.
The layers were separated and the upper organic layer was washed
with 4443 g of saturated aqueous sodium carbonate. The layers were
separated, and the organic layer dried over magnesium sulfate,
filtered, and concentrated on a rotary evaporator to provide the
intermediate N-(acryloyloxyethyl)-N,N-diethyl amine. A cylindrical
reactor under an air atmosphere equipped with overhead stirrer and
reflux condenser was charged with 600 g (3.49 mol)
N-(acryloyloxyethyl)-N,N-diethyl amine, 24.74 g (0.21 mol) sodium
carbonate, 0.15 g MEHQ, and 0.03 g phenothiazine at 23.degree. C.
Next 462.7 g (3.67 mol) dimethyl sulfate was added via dropping
funnel over 5 hours with the reaction reaching a maximum
temperature without added heating of 60.4.degree. C. The
intermediate
(CH.sub.3CH.sub.2).sub.2N(CH.sub.3)CH.sub.2CH.sub.2OC(O)CH.dbd.CH.sub.2.s-
up.+-O.sub.3SOCH.sub.3 was dissolved in 512.3 g deionized water,
and removed from the reactor, which was rinsed with an additional
100 g of deionized water. This solution was filtered through
cheesecloth to remove particulates into a 6 L Erlenmeyer flask. To
the Erlenmeyer was added with overhead stirring over 1 min 1218 g
(82.3% solids in water, 3.49 mol) HQ-115. After 10 min of stirring,
the lower organic layer was separated, washed with 612 g of
deionized water, diluted with 700 g acetone, dried over magnesium
sulfate, filtered, treated with 0.32 g MEHQ and 0.08 g
phenothiazine, and concentrated on a rotary evaporator to yield
1394 g of POS-2 as a yellow oil.
Preparation of
(CH.sub.3CH.sub.2).sub.2N(CH.sub.3)CH.sub.2CH.sub.2OC(O)C(CH.sub.3).dbd.C-
H.sub.2.sup.+-N(SO.sub.2CF.sub.3).sub.2;
methacryloyloxyethyl)-N,N-diethyl-N-methylammonium
bis(trifluoromethane sulfonyl)imide (Referred to Herein as
POS-3)
[0120] A cylindrical reactor under an air atmosphere, equipped with
overhead stirrer and reflux condenser was charged with 500 g (2.69
mol) AGEFLEX.TM. FM2*PTZ, 19.06 g (0.16 mol) sodium carbonate, 0.10
g MEHQ, and 0.02 g phenothiazine, and heated to 39.5.degree. C.
Next 356.5 g (2.83 mol) dimethyl sulfate was added via dropping
funnel over 2.25 hour with the reaction reaching a maximum
temperature without added heating of 76.3.degree. C. After 3.25
hour a sample was taken for .sup.1H NMR analysis, and at 4.25 hour
the reaction was heated to 50.degree. C. The intermediate
(CH.sub.3CH.sub.2).sub.2N(CH.sub.3)CH.sub.2CH.sub.2OC(O)C(CH.sub.3).dbd.C-
H.sub.2.sup.+-O.sub.3SOCH.sub.3 was diluted with 504 g deionized
water to form a solution. To the reaction at 50.degree. C. was
added 987.94 g (79.8% solids in water, 2.75 mol) HQ-115 over one
minute. After 30 min, the bottom organic layer was separated,
washed at 50.degree. C. with 504 g of deionized water, separated
from the aqueous layer, diluted with 600 g of acetone, dried over
anhydrous magnesium sulfate, filtered, and concentrated by rotary
evaporation to provide 1269 g of POS-3 product as a yellow oil.
Preparation of
(CH.sub.3CH.sub.2CH.sub.2CH.sub.2).sub.2N(CH.sub.3)CH.sub.2CH.sub.2OC(O)C-
H.dbd.CH.sub.2.sup.+-N(SO.sub.2CF.sub.3).sub.2;
acryloyloxyethyl-N,N-dibutyl-N-methylammonium
bis(trifluoromethanesulfonyl)imide (referred to as POS-4)
[0121] Using a preparation similar to that for
(C.sub.2H5).sub.2N(CH.sub.3)CH.sub.2CH.sub.2OC(O)CH.dbd.CH.sub.2.sup.+-N(-
SO.sub.2CF.sub.3), 500 g (2.89 mol) N-(hydroxyethyl)-N,N-dibutyl
amine (C.sub.4H.sub.9).sub.2NCH.sub.2CH.sub.2OH in 1064 g MTBE with
0.0394 g phenothiazine was reacted with 287.25 g (3.174 mol)
acryloyl chloride and 276.98 g (3.46 mol) 50% aqueous sodium
hydroxide, to yield after workup with 17.33 g acetic acid in water,
followed by washing with 354.7 g deionized water, drying over
magnesium sulfate, filtering, treatingd with 0.10 g MEHQ and 0.025
g phenothiazine, 441.2 g of slightly yellow product,
(C.sub.4H.sub.9).sub.2NCH.sub.2CH.sub.2OC(O)CH.dbd.CH.sub.2.
Combined preparations of 525 g (2.31 mol)
(C.sub.4H.sub.9).sub.2NCH.sub.2CH.sub.2OC(O)CH.dbd.CH.sub.2 were
reacted in the presence of 16.35 g (0.139 mol) sodium carbonate
with 305.85 g (2.425 mol) dimethyl sulfate to form the intermediate
(C.sub.4H.sub.9).sub.2N(CH.sub.3)CH.sub.2CH.sub.2OC(O)CH.dbd.CH.sub.2.sup-
.+-O.sub.3SOCH.sub.3 (referred to herein as POS-5), which is a
solid melting above 70.degree. C. This intermediate (with no
filtration) (816.3 g (2.31 mol)) was dissolved in 612.2 g deionized
water and reacted with 804.3 g (82.3% solids in water, 2.31 mol)
HQ-115, to form a lower organic layer which was washed with an
additional 612 g deionized water, separated, diluted with 600 g
acetone, dried over magnesium sulfate, filtered, and concentrated
on a rotary evaporator to yield 1164.6 g POS-4 as a brownish
oil.
Preparation of
(C.sub.4H.sub.9).sub.2N(CH).sub.3CH.sub.2CH.sub.2OC(O)CH.dbd.CH.sub.2.sup-
.+-O.sub.3SCF.sub.3; acryloyloxyethyl-N,N-dibutyl-N-methylammonium
trifluoromethanesulfonate (Referred to Herein as POS-6)
[0122] A 500 mL round bottom flask equipped with an overhead
stirrer was charged with 100.0 g (0.269 mol)
(C.sub.4H.sub.9).sub.2N(CH.sub.3)CH.sub.2CH.sub.2OC(O)CH.dbd.CH.sub.2.sup-
.+-O.sub.3SOCH.sub.3, 100 g of deionized water, 0.0923 g MEHQ, and
0.023 g phenothiazine. Next, 111.37 g (72% solids in water, 0.269
mol) lithium trifluoromethane sulfonate was added. After 15 min of
stirring, 150 g of dichloromethane was added to the reaction, and
after 5 min of stirring, the lower dichloromethane layer was
separated. The aqueous layer was re-extracted with another 150 g of
dichloromethane. The two dichloromethane extracts were combined,
along with 30 g of additional dichloromethane used for washing
glassware containing the dichloromethane layers, and were washed
with 100 g of deionized water. The organic layers were dried over
magnesium sulfate, filtered, and concentrated on a rotary
evaporator to yield 97.59 g of POS-6 as a light tan solid.
Preparation of
(C.sub.4H.sub.9).sub.2N(CH).sub.3CH.sub.2CH.sub.2OC(O)CH.dbd.CH.sub.2.sup-
.+-C(SO.sub.2CF.sub.3F.sub.3).sub.3;
acryloyloxyethyl-N,N-dibutyl-N-methylammonium
tris(trifluoromethanesulfonyl)methide (Referred to Herein as
POS-7)
[0123] Tris(trifluoromethanesulfonyl)methane,
HC(SO.sub.2CF.sub.3).sub.3, 75.0 g (60% solids in water, 0.10 mol)
was neutralized with 4.55 g (0.10 mol) lithium hydroxide
monohydrate to a pH of 0. With addition of 1.2 g more lithium
hydroxide monohydrate (total of 5.75 g) the pH rose to 2. Addition
of 0.81 g more lithium hydroxide monohydrate (total of 6.56 g) the
pH rose to 14. Addition of 7.08 g of the
tris(trifluoromethanesulfonyl)methane left the pH of the solution
at pH of 14. Solution was assumed to have all of the acid
neutralized and was used as prepared to provide a 51.37% solids of
an aqueous lithium tris(trifluoromethanesulfonyl)methide solution.
A 250 mL round bottom flask equipped with overhead stirrer was
charged with 20.0 g (0.538 mol)
(C.sub.4H.sub.9).sub.2N(CH.sub.3)CH.sub.2CH.sub.2OC(O)CH.dbd.CH.sub.2.sup-
.+-.sub.3SOCH.sub.3, 30 g of deionized water, 0.0295 g MEHQ, and
0.007 g phenothiazine, to which was added 87.59 g (51.37% solids,
0.0538 mol) lithium tris(trifluoromethanesulfonyl)methide. After
stirring for a few minutes, 30 g MTBE was added and stirring
continued for 30 min, at which time the reaction was allowed to
separate between an upper aqueous layer and a lower organic layer.
The organic layer was washed with 30 g of deionized water, dried
over anhydrous magnesium sulfate, filtered and concentrated on a
rotary evaporator to yield 34 g POS-7 as a brown liquid.
Preparation of
C.sub.8H.sub.17N(CH.sub.3).sub.2CH.sub.2CH.sub.2OC(O)CH.dbd.CH.sub.2.sup.-
+-N(SO.sub.2CF.sub.3).sub.2;
acryloyloxyethyl-N,N-dimethyl-N-octylammonium
bis(trifluoromethanesulfonyl)imide (Referred to Herein as
POS-8)
[0124]
C.sub.8H.sub.17N(CH.sub.3).sub.2CH.sub.2CH.sub.2OH.sup.+-N(SO.sub.2-
CF.sub.3).sub.2 is prepared as described in Example 1 of U.S. Pat.
No. 6,372,829. A 500 mL, 3-necked roundbottom flask with overhead
stirrer was charged with 125 g (0.259 mol)
C.sub.8H.sub.17N(CH.sub.3).sub.2CH.sub.2CH.sub.2OH.sup.+-N(SO.sub.2CF.sub-
.3).sub.2, 35.39 g (0.350 mol) triethylamine, and 190.87 g MTBE.
The flask was cooled in an ice bath and 30.48 g (0.337 mol)
acryloyl chloride was added over 30 min. After 1 hour, 125 ml of
about 0.02M HCl was added to the flask and with stirring for 5 min.
The layers were separated and the top organic layer was washed with
130 g of saturated aqueous sodium carbonate for 30 min. The top
organic layer was separated, dried over magnesium sulfate, filtered
and concentrated to yield 131.3 g POS-8 as a yellow oil.
Preparation of
C.sub.16H.sub.33N(CH.sub.3).sub.2CH.sub.2CH.sub.2OC(O)CH.dbd.CH.sub.2.sup-
.+-N(SO.sub.2CF.sub.3).sub.2;
acryloyloxyethyl)-N,N-dimethyl-N-hexadecylammonium
bis(trifluoromethane sulfonyl)imide (Referred to Herein as
POS-9)
[0125] A three neck 3 L round bottom reaction flask equipped with
overhead stirrer, condenser, and temperature probe was charged with
234 weight parts of AGEFLEX.TM. FA 1, 617 parts of acetone, 500
parts of 1-bromohexadecane, and 0.5 parts of BHT
(butylhydroxytoluene, antioxidant added as inhibitor to prevent
premature polymerization). The mixture was heated to 35.degree. C.
by using two IR lamps with stirring at 150 rpm. After 24 hours of
heating the reaction mixture was cooled to room temperature. The
clear reaction solution was transferred to a round bottom flask and
acetone was removed by rotary evaporation under vacuum at
40.degree. C. The resulting solid residue was mixed with 1 L cold
ethyl acetate and mixed for 10 min. The mass was filtered and the
solid product was washed with 500 ml cold ethyl acetate. The solid
product was transferred to a tray and dried overnight in a vacuum
oven at 40.degree. C. to yield
acryloyloxyethyl-N,N-dimethyl-n-hexadecyl ammonium bromide. A
2-necked, 500 ml round bottom flask equipped with overhead stirrer
was charged with 25.0 g (0.558 mol)
acryloyloxyethyl-N,N-dimethyl-n-hexadecyl ammonium bromide, and 80
g of deionized water, and was heated in a 65.degree. C. oil bath.
Next, 39.56 g (80.97% solids in water, 0.0558 mol) HQ-115 was added
in one portion to the heterogeneous mixture, and stirred for 1 hour
at 65.degree. C., providing two liquid phases. The reaction mixture
was allowed to cool to 40.degree. C. and 49.89 g of MTBE was added
to the reaction mixture with stirring. After 5 min, the reaction
mixture separated into a lower aqueous layer and an upper organic
layer. The aqueous layer was extracted twice with 25 g MTBE. The
combined MTBE layers were washed twice with 50 g of deionized
water, dried over anhydrous magnesium sulfate, filtered and
concentrated on a rotary evaporator to yield 39.2 g POS-9 as a
yellow liquid.
Preparation of
(CH.sub.3).sub.3NCH.sub.2CH.sub.2OC(O)CH.dbd.CH.sub.2.sup.+-OSO.sub.2CF.s-
ub.3; acryloxyethyl-N,N,N-trimethylammonium
trifluoromethanesulfonate (Referred to Herein as POS-10)
[0126] A 250 mL, 3-neck round bottom flask equipped with overhead
stirring was charged with 50.00 g (79.9% solids in water, 0.2063
mol) of AGEFLEX.TM. FA1Q80MC*500 and 15.00 g deionized water. This
solution was heated in an oil bath to 45.degree. C. To the solution
was rapidly added, over 10 seconds, 42.91 g (75% solids in water,
0.2063 mol) lithium trifluoromethanesulfonate
(Li.sup.+-OSO.sub.2CF.sub.3), after 1.5 hrs, 75 g of
dichloromethane was added to initiate a phase split. Resultant
biphasic system was transferred to a reparatory funnel and the
bottom (organic) layer was washed with 50 g deionized water. The
resultant aqueous phase was combined with the first aqueous phase
and distilled at 80.degree. C. with an air bubbler and a slight
aspirator vacuum to yield 53 g POS-10 as a thick white liquid which
solidified into a flaky white wax.
Preparation of
(CH.sub.3).sub.3NCH.sub.2CH.sub.2OC(O)CH.dbd.CH.sub.2.sup.+-OSO.sub.2C.su-
b.4F.sub.9; acryloxyethyl-N,N,N-trimethylammonium
(1,1,1,2,2,3,3,4,4-nonafluoro)butanesulfonate (Referred to Herein
as POS-11)
[0127] A 250 mL, 3-neck round bottom flask equipped with overhead
stirring was charged with 50.00 g (79.9% solids in water, 0.2063
mol) of AGEFLEX.TM. FA1Q80MC*500 and 20.11 g deionized water. This
solution was heated in an oil bath to 45.degree. C. To the solution
was rapidly added, over 10 seconds, 140.28 g (40% solids in water,
0.2063 mol) lithium (1,1,1,2,2,3,3,4,4-nonafluoro)butanesulfonate
(Li.sup.+-OSO.sub.2C.sub.4F.sub.9), after 1.5 hrs, the biphasic
system was transferred to a separatory funnel and the bottom
(organic) layer was washed with 50 g deionized water. The resultant
organic phase was distilled at 80.degree. C. with an air bubbler
and a slight aspirator vacuum to yield 73 g POS-11 as a thick white
liquid which solidified into a breakable white solid.
Preparation of
(CH.sub.3CH.sub.2CH.sub.2CH.sub.2).sub.2N(CH.sub.3)CH.sub.2CH.sub.2OC(O)C-
H.dbd.CH.sub.2.sup.+-OSO.sub.2C.sub.4F.sub.9;
acryloxyethyl-N,N-dibutyl-N-methylammonium
(1,1,1,2,2,3,3,4,4-nonafluoro) butanesulfonate (Referred to Herein
as POS-12)
[0128] A 1 L, 3-neck round bottom flask equipped with overhead
stirring was charged with 100.00 g (100% solids, 0.4390 mol) of
acryloxyethyl-N,N-dibutylamine. This solution was set to stirring
at 45.degree. C., and 56.46 g (1.02 eq., 0.4477 mol)
dimethylsulfate was added dropwise over 1 hr, under air. After
approximately 25% of the DMS was added, 123 g acetone was added to
solubilize the product, which is a tan-colored solid; the
temperature was lowered to 40.degree. C. Reaction progressed for a
total of 4 hours, whereupon the acetone was distilled off at
56.degree. C. and atmospheric pressure for 1 hr, then under a water
aspirator vacuum for 1 hr. Final product is a tan to yellow-colored
solid, which was not isolated directly. This solid was dissolved in
156 g deionized water, and set to stirring at 45.degree. C. Over
the course of 1 min, 335.84 g (40% solids in water, 0.4390 mol)
lithium (1,1,1,2,2,3,3,4,4-nonafluoro)butanesulfonate
(Li.sup.+-OSO.sub.2C.sub.4F.sub.9) was added. 100 g deionized water
was added to aid in lowering the viscosity of the solution. The
temperature was increased to 50.degree. C. and an aliquot was taken
and filtered through a ceramic filter with filter paper. The
resultant white solid met our assumptions of product consistency,
and the entire reaction was then filtered in the same manner. The
filter cake was washed 4 times with 100 g deionized water, and the
solid was broken up by hand into a finer powder and dried in a
50.degree. C. oven overnight. Isolated yield of POS-12 was 203.9 g
white/tan colored solid.
Preparation of
(CH.sub.3).sub.3NCH.sub.2CH.sub.2OC(O)CH.dbd.CH.sub.2.sup.+-O.sub.3SOCH.s-
ub.3; acryloyloxyethyl-N,N,N-trimethylammonium methylsulfate
(Referred to Herein as POS-13)
[0129] A 250 mL round bottom flask equipped with an overhead
stirrer and fitted with a reflux condenser was charged with 50 g
(0.349 mol) dimethylaminoethyl acrylate. The flask was placed in an
oil bath at room temperature under dry air, and a pressure
equalizing addition funnel charged with 44.03 g (0.349 mol)
dimethyl sulfate was added over 5.5 h. The oil bath temperature was
raised to 30.degree. C. at 2 h with 50% of the dimethyl sulfate
addition complete. The bath temperature was raised to 40.degree.
C., at 3 h with 75% of the dimethyl sulfate addition complete. The
bath temperature was raised to 60.degree. C., at 3.5 h with 80% of
the dimethyl sulfate addition complete. At 6.75 h the bath was
heated to 80.degree. C., and POS-13 was isolated as a brown-yellow
liquid.
Preparation of
C.sub.12H.sub.25N(CH.sub.3)(CH.sub.2CH.sub.2OC(O)CH.dbd.CH.sub.2).sub.2.s-
up.+-N(SO.sub.2CF.sub.3).sub.2;
bis-(acryloyloxyethyl)-N-methyl-N-dodecylammonium
bis(trifluoromethanesulfonyl)imide (Referred to Herein as
POS-14)
[0130] POS-14 was prepared as described in Preparation of
Antistatic Agent C in U.S. Patent Appln. Publn. No. 2007141329. A
250 mL, 3-necked round bottom flask with overhead stirrer was
charged with 40 g (0.0706 mol)
C.sub.12H.sub.25N(CH.sub.3)(CH.sub.2CH.sub.2OH).sub.2.sup.+-N(SO.sub.2CF.-
sub.3).sub.2, 17.14 g (0.1694 mol) triethylamine, and 71.84 g
dichloromethane. The flask was cooled in an ice bath and 14.70 g
(0.1624 mol) acryloyl chloride was added over 45 min. After 2.25
hour more, 71.84 ml of water was added to the flask and with
stirring for 10 min. The layers were separated, a few hundred ppm
of 4-methoxyphenol (MEHQ, Sigma-Aldrich) were added to the top
organic layer which was concentrated to yield 50 g POS-14 as a
orange colored oil.
Examples 1 to 12
Antistatic Coating Compositions
[0131] For Examples 1 to 12, a variety of liquid UV-curable
antistatic coating compositions were prepared by mixing 40 parts by
weight of the polymerizable onium salt POS-1, with 35 parts of a
monofunctional acrylate, 25 parts of a multifunctional acrylate,
and 0.5 parts of IRGACURE.TM. 819 as photoinitiator. The
monofunctional acrylates used were selected as indicated from the
following: SR 339 (2-phenoxy ethyl acrylate), EBECRYL.TM. 110
(ethoxylated.sub.2 phenol acrylate), CD 9087 (ethoxylated.sub.3
phenol acrylate), and CD 9088 (ethoxylated.sub.6 phenol acrylate).
The multifunctional acrylates used were selected as indicated from
the following: EBECRYL.TM. 8402 (aliphatic urethane diacrylate), SR
494 (ethoxylated trimethylolpropane triacrylate), and SR 9035
(ethoxylated.sub.4 pentaerythritol tetraacrylate). The specific
antistatic coating formulations are shown in Table 1 below. Each
mixture was heated to 60.degree. C. for 30 minutes in a sealed
sample bottle, shaken vigorously by hand to mix, and then allowed
to cool at ambient conditions. At room temperature all the
solutions were homogeneous, clear, slightly yellow due to the
photoinitiator, and of modest viscosity.
TABLE-US-00002 TABLE 1 Antistatic Coating Composition (parts by
weight) Polymerizable Onium Salt Acryloyloxyethyl- Multifunctional
Acrylate Monofunctional Acrylates N,N,N-trimethyl- Aliphatic
Ethoxylated Ethoxylated.sub.4 2-Phenoxy Ethoxylated.sub.2
Ethoxylated.sub.3 Ethoxylated.sub.6 ammonium bis(trifluoro- Exam-
Urethane Trimethylolpropane Pentaerythritol Ethyl Phenol Phenol
Phenol methanesulfonyl)imide Photo- ple Diacrylate Triacrylate
Tetraacrylate Acrylate Acrylate Acrylate Acrylate (POS-1) initiator
1 25 0 0 35 0 0 0 40 0.5 2 25 0 0 0 35 0 0 40 0.5 3 25 0 0 0 0 35 0
40 0.5 4 25 0 0 0 0 35 40 0.5 5 0 25 0 35 0 0 0 40 0.5 6 0 25 0 0
35 0 0 40 0.5 7 0 25 0 0 0 35 0 40 0.5 8 0 25 0 0 0 0 35 40 0.5 9 0
0 25 35 0 0 0 40 0.5 10 0 0 25 0 35 0 0 40 0.5 11 0 0 25 0 0 35 0
40 0.5 12 0 0 25 0 0 0 35 40 0.5
[0132] Coating and Cure of Antistatic Formulations
[0133] A laboratory scale coating device was used to fabricate
coated film samples. The coating apparatus as well as the coating
procedures that were followed are described in detail in U.S. Pat.
No. 6,899,922. The apparatus was used to precisely apply
continuous, void-free, and uniform coatings of liquid UV-curable
antistatic coating compositions onto rectangular pieces of
VIKUITI.TM. DBEF II film (3M). The film specimens for coating were
circumferentially wrapped around the mounting roll of the apparatus
such that the ends of the film met nearly flush with no gap and
minimal overlap. The mounting roll was then placed atop the primary
and secondary pick-and-place rolls such that the film was nipped
between the mounting roll and each of these two supporting
auxiliary rolls. Coating thickness was controlled by the precise
dispensing of a known volume of coating formulation via syringe
pump, model FUSION.TM. 200 (Chemyx, Inc., Stafford, Tex.). An
oscillating delivery system was used to distribute the metered
coating volume via a 1/16 inch (1.6 mm) ID piece of flexible
TYGON.TM. tubing across the operating width of the primary transfer
roll, as the three rolls of the apparatus were driven to rotate.
This effectively delivered the coating as multiple beads, in helix
patterns of opposite hand, on the operating width of the primary
roll thus providing cross wise coating uniformity. Rotation of the
rolls was maintained after the full complement of coating volume
had been dispensed onto the primary roll such that the wetted
surfaces of the primary and secondary rolls continuously contacted
the film surface on the mounting roll. The coating formulation was
thus picked up from and placed back on to the film substrate,
randomly and repeatedly, by the auxiliary rolls. The rolls of the
coating device were rotated for a plurality of revolutions until
the coating was evenly distributed in the direction of roll
rotation. In this way, uniform coverage was achieved over the test
coating area on the VIKUITI.TM. DBEF II film piece, with that area
being defined by the operating width of the primary and secondary
transfer rolls and the circumference of the mounting roll. The
syringe delivery volumes were set to achieve coating thicknesses of
1, 2, 3, and 4 microns for each of the formulations in Table 1. All
antistatic coatings were carried out at room temperature. This
apparatus is hereafter referred to as the laboratory scale
multi-roll coater.
[0134] The coating formulations, applied as described above, were
cured using a UV processor outfitted with a FUSION.TM. UV D bulb,
from Fusion UV Systems Inc. (Gaithersburg, Md.). Coated specimens
were first preheated by placing each specimen, with its coated side
facing up, onto a temperature controlled heating platen at
140.degree. F. (60.degree. C.) for 30 seconds. The specimen was
then placed immediately onto the conveyer of the UV processer which
then carried the specimen through the cure chamber at 30 ft/min.
(9.1 m/min.), with the D bulb power setting set at 100%. The coated
side was oriented to face the UV source. The cure chamber was
purged with nitrogen so as to effect the cure under essentially
oxygen free conditions. Upon recovery from the UV processor the
coatings were clear, smooth, and solid in nature, at room
temperature as evidenced by touching and rubbing the cured
coatings.
[0135] Characterization of Antistatic Coatings
[0136] The charge decay was measured for each formulation coating
on VIKUITI.TM. DBEF II at each coating thickness as per procedures
documented above. The average of six determinations was reported
for each formulation at each coating thickness (1, 2, 3, and 4
microns) as delivered onto VIKUITI.TM. DBEF II film, and these are
shown in Table 2, in the column labeled "DBEF II with Antistatic
Coating".
[0137] Prism Overcoat Procedure
[0138] The antistatic coatings as applied on each VIKUITI.TM. DBEF
II specimen in Table 2 were subsequently over-coated with 90
degree, 50 pitch, BEF prisms using an optical grade acrylate resin
similar to that cited in US Patent Appin Publn. No. 2009/0017256
(Hunt et al.), Resin R8 of Table 1, with the exception that 1.0%
rather than 0.3% of the photoinitiator was used. A 14 inch.times.18
inch (36 cm.times.46 cm) flat tool with a 90.degree. included angle
prism geometry at a pitch of 50 microns, and having a repeating
pattern of prism zones which includes a first zone having a
plurality of prism elements which have their peaks disposed at a
first distance above a reference plane and a second zone having a
plurality of prism elements which have their peaks disposed at a
lesser distance from the reference plane as described in U.S. Pat.
No. 5,771,328 (Wortman et al.), was mounted on a 3/16 inch (4.8 mm)
aluminum plate for mechanical support and heat retention
characteristics. The tool was arranged with the axis of the prisms
parallel to the long axis of the tool (18 inch; 46 cm). This
assembly was preheated to 140.degree. F. (60.degree. C.) on a
thermally controlled hot plate set at this target temperature. A
caulk-sized bead of optical acrylate resin was applied to the top
14 inch (36 cm) edge of the tool. Next, a specimen of antistatic
coated VIKUITI.TM. DBEF II was laminated to the tool with the cured
antistatic coated surface facing the tool. A laboratory roll
lamination machine (model Catena 35 available from General Binding
Corporation of Northbrook, Ill.) was then used for the BEF prism
coating procedure. The lab scale laminator was run at a gap setting
of 3/16 inch (4.8 mm), a roll temperature of 140.degree. F.
(60.degree. C.), and speed setting of 3. As the specimen progressed
through the nip rolls of the laminator, with the edge having the
bead of optical acrylate resin as the leading edge, the bead of
optical grade acrylate was spread in a thin layer down the long
axis of the tool such that the uncured optical acrylate resin
evenly wetted the antistatic coating and concomitantly filled the
prism geometry of the tooling. Immediately after lamination the
specimen was cured on the tool using a laboratory scale UV
processor outfitted with a FUSION.TM. UV D bulb, from Fusion UV
Systems Inc. The laminate was processed with the VIKUITI.TM. DBEF
II film facing the UV source such that the sandwiched optical resin
was cured by UV light passing through the DBEF II film and
proceeding through the resin toward the tooling. The line speed of
the UV processor was 30 ft/min (9.1 m/min) and the UV power was set
at 100%. Nitrogen purge was not used during the cure. The finished
prototype specimen was removed from the tool immediately after
curing for characterization. This provided a continuous cured BEF
prism coat over the antistatic coating, with overall continuous
prism structure thickness of 26 to 28 microns.
[0139] Characterization of the Prism Over-Coated Antistatic
Samples
[0140] The prism-coated specimens were again characterized for
charge decay after the requisite preconditioning cycle (12 hours at
nominal 50% RH and RT) using the same test procedures as used to
characterize the specimens prior to BEF prism overcoat. These
results are reported in Table 2 in the column labeled "DBEF II with
Antistatic Coating and Prism Overcoat".
[0141] Determination of Antistatic Coating Glass Transition
Temperature
[0142] Each of the same formulations as shown in Table 1 was
smeared onto unprimed 5 mil (127 micron) PET film. A coating bar
was used, resulting in much thicker though less uniform coatings of
10 to 20 microns. These specimens were then cured under the same
preheat regimen and UV process conditions as described above for
the cure of antistatic coatings on VIKUITI.TM. DBEF II. Each cured
specimen was easily removed from the unprimed PET film and
recovered for DSC characterization of the glass transition
temperature using the test procedures outlined above. The T.sub.gs
from the DSC heating scan are reported in Table 2 in the column
labeled "Glass Transition Temperature from DSC".
[0143] Charge Decay and Glass Transition Temperatures
[0144] Most of the coated film examples summarized in Table 2 show
excellent antistatic characteristics as indicated by their lower
charge decay values. These formulations each include 40% of
acryloyloxyethyl-N,N,N-trimethylammonium
bis(trifluoromethanesulfonyl)imide (POS-1) which is believed to be
the active agent for antistatic performance, yet there were
significant differences in measured charge decay even at comparable
thickness of the cured coating onto VIKUITI.TM. DBEF II film.
Examination of these charge decay differences in light of the DSC
data suggests that lower glass transition temperatures favored
better charge decay. For values of T.sub.g below -10.degree. C.
charge decay values of the formulations as coated and cured onto
VIKUITI.TM. DBEF II were often well below 0.1 seconds, sometimes
approaching 0.01 seconds. On the other extreme, if the glass
transition of the cured formulation was too high, then the charge
decay of the coated film was higher, and can be too high to be
useful as an antistatic construction for some uses. A specific
example of this was found in Example 5 wherein the T.sub.g of the
cured formulation is 36.6.degree. C. and associated charge decay of
coated VIKUITI.TM. DBEF II was in excess of 17 seconds for coating
thicknesses from 1 to 4 microns.
[0145] Surprisingly, the antistatic performance did not suffer from
over-coating with BEF prisms and in many cases actually improved
(charge decay decreased) after over-coating with BEF prisms. For
example, the formulation of Example 7 as coated and cured onto
VIKUITI.TM. DBEF II to a final thickness of approximately 1 micron
had a charge decay of 1.98 seconds. After overcoating with BEF
prisms the final construction had a charge decay of 0.59 seconds.
This charge decay time is sufficiently low as to dissipate charge
on a time scale of significance for preventing defects in the
assembly of brightness enhancement films into backlight
assemblies.
TABLE-US-00003 TABLE 2 Examples 1 to 12 Charge Decay and Glass
Transition Temperature Average Charge Decay (seconds) Antistatic
Coating DBEFII with DBEFII with T.sub.g Thickness Antistatic
Antistatic Coating Example (.degree. C.) (microns) Coating and
Prism Overcoat 1 13.9 1 4.57 1.10 2 3.92 0.65 3 2.59 0.29 4 2.57
0.28 2 -2.5 1 0.35 0.19 2 0.31 0.08 3 0.22 0.06 4 0.15 0.05 3 -8.6
1 0.63 1.00 2 0.24 0.14 3 0.10 0.05 4 0.11 0.06 4 -20.4 1 0.09 0.63
2 0.04 0.05 3 0.02 0.03 4 0.02 0.02 5 36.6 1 29.73 13.32 2 17.46
10.74 3 18.29 13.28 4 24.98 12.16 6 10.8 1 1.17 1.10 2 1.35 0.67 3
1.76 0.81 4 0.73 0.72 7 2.7 1 1.98 0.59 2 0.66 0.21 3 0.56 0.13 4
0.47 0.12 8 -16.7 1 0.11 0.08 2 0.06 0.04 3 0.05 0.04 4 0.03 0.02 9
5.8 1 0.17 0.13 2 0.14 0.07 3 0.15 0.05 4 0.10 0.05 10 -9.8 1 0.05
0.05 2 0.02 0.02 3 0.02 0.02 4 0.01 0.01 11 -16.3 1 0.03 0.05 2
0.01 0.02 3 0.01 0.02 4 0.01 0.01 12 -24.0 1 0.02 0.05 2 0.01 0.02
3 0.01 0.01 4 0.01 0.01
Comparative Examples C13 and C14
[0146] For comparison, the charge decay of VIKUITI.TM. DBEF II film
without an antistatic coating and DBEF II film with 90 degree 50
pitch prisms coated directly onto film without an intervening
antistatic coating were measured for charge decay. Each of these
specimens failed to accept a minimum charge of at least 4000 volts
and as such were not considered to be antistatic in nature.
Comparative Examples C15 to C20
[0147] Coating compositions for Comparative Examples C15 to C20
were designed to be analogous to Examples 1 to 5 and Example 12,
respectively, but without the polymerizable onium salt.
Formulations are indicated in Table 3.
TABLE-US-00004 TABLE 3 Comparative Coating Composition (parts by
weight) Multifunctional Acrylate Monofunctional Acrylates Aliphatic
Ethoxylated Ethoxylated.sub.4 2-Phenoxy Ethoxylated.sub.2
Ethoxylated.sub.3 Ethoxylated.sub.6 Exam- Urethane
Trimethylolpropane Pentaerythritol Ethyl Phenol Phenol Phenol Onium
Salt Photo- ple Diacrylate Triacrylate Tetraacrylate Acrylate
Acrylate Acrylate Acrylate -- initiator C15 41.7 0 0 58.3 0 0 0 0
0.5 C16 41.7 0 0 0 58.3 0 0 0 0.5 C17 41.7 0 0 0 0 58.3 0 0 0.5 C18
41.7 0 0 0 0 0 58.3 0 0.5 C19 0 41.7 58.3 0 0 0 0.5 C20 0 0 41.7 0
0 0 58.3 0 0.5
[0148] Using the same procedures as described for Examples 1 to 12,
the mixtures in Table 3 were each heated to 60.degree. C. for 30
minutes in sealed sample bottles, shaken vigorously by hand to mix,
and finally allowed to cool at ambient conditions. At room
temperature the solutions of Comparative Examples C15 to C20 were
similar to their counterparts (Examples 1 to 5 and 12) and found to
be homogeneous, clear, and slightly yellow due to the
photoinitiator.
[0149] Coating of the formulations of Comparative Examples C15 to
C20 onto VIKUITI.TM. DBEF II was accomplished using the same
procedures and apparatus as outlined above with the exception that
these comparative coating examples were prepared at only a single
coating thickness of 4 microns. Over-coating of the 4 micron
coatings with 90.degree., 50 pitch BEF prisms was conducted as
already described. Table 4 documents the glass transition
temperature of each cured formulation, the charge decay of the 4
micron coating formulations on VIKUITI.TM. DBEF II, and finally the
charge decay of the specimens of the 4 micron coatings on
VIKUITI.TM. DBEF II after over coat with the BEF prisms. These data
can be directly compared to the results of Examples 1 to 5 and
Example 12 shown in Table 2.
TABLE-US-00005 TABLE 4 Comparative Examples C15 to C20 Charge Decay
and Glass Transition Temperature Average Charge Decay Antistatic
(seconds) Coating DBEFII DBEFII with Acrylate T.sub.g Thickness
with Acrylate Coating and Prism Example (.degree. C.) (microns)
Coating Overcoat C15 4.74 4 wnc wnc C16 -12.99 4 greater than
greater than 100 sec 100 sec C17 -19.94 4 90.90 greater than 100
sec C18 -34.43 4 2.17 6.18 C19 28.23 4 wnc wnc C20 -36.24 4 0.76
2.01
[0150] Generally, the charge decay of all samples with prism over
coat in Table 4 indicated that either the samples were not
antistatic (designated as wnc) or had charge decay times so long
that they were deemed not practically useful as antistatic optical
film constructions.
Examples 21 to 33
[0151] Table 5 documents a series of antistatic coating
formulations that were prepared using various charges of the
polymerizable onium acryloyloxyethyl-N,N,N-trimethylammonium
bis(trifluoromethanesulfonyl)imide. The amount of polymerizable
onium salt in these formulations ranges from 0.5 wt % to 90 wt %,
with composition determined as a weight percent of the total
acrylate charged. The same multifunctional and mono-functional
acrylate pair was used with the polymerizable onium salt in each of
these formulations. The multifunctional acrylate used was
EBECRYL.TM. 8402. The monofunctional acrylate used was SR 339.
Compositions were formulated such that the mass ratio of the
EBECRYL.TM. 8402 to the SR 339 was constant at 0.714. The
photoinitiator used was IRGACURE.TM. 819. The specific antistatic
coating formulations for Examples 21 to 33 are shown in Table 5. As
in previous examples, these mixtures were each heated to 60.degree.
C. for 30 minutes in sealed sample bottles, shaken vigorously by
hand to mix, and finally allowed to cool at ambient conditions. At
room temperature all the solutions were homogeneous, clear,
slightly yellow due to the photoinitiator, and of modest
viscosity.
TABLE-US-00006 TABLE 5 Antistatic Coating Composition (parts by
weight) Polymerizable Onium Salt Acryloyloxyethyl- Multifunctional
Acrylate Monofunctional Acrylates N,N,N-trimethylammonium Aliphatic
Urethane 2-Phenoxy Ethyl bis(trifluoromethanesulfonyl)imide Example
Diacrylate Acrylate (POS-1) Photoinitiator 21 41.46 58.04 0.5 0.5
22 41.25 57.75 1 0.5 23 40.83 57.17 2 0.5 24 39.58 55.42 5 0.5 25
37.50 52.50 10 0.5 26 33.33 46.67 20 0.5 27 25.00 35.00 40 0.5 28
22.92 32.08 45 0.5 29 20.83 29.17 50 0.5 30 18.75 26.25 55 0.5 31
16.67 23.33 60 0.5 32 8.33 11.67 80 0.5 33 4.17 5.83 90 0.5
[0152] Formulations of Examples 21 to 33 were coated and cured onto
VIKUITI.TM. DBEF II using the same procedures and apparatus as
outlined above with the exception that these examples were limited
to a single antistatic coating thickness of 3 microns. Overcoat of
the 3 micron antistatic coatings with 90.degree., 50 pitch BEF
prisms was also similarly completed. Table 6 documents the glass
transition temperature of each cured antistatic formulation, the
charge decay of the 3 micron coating formulations on VIKUITI.TM.
DBEF II, and the charge decay of the specimens of the 3 micron
coatings on VIKUITI.TM. DBEF II after overcoating with the BEF
prism structure, performed as in previous Examples. In addition,
the cross hatch peel adhesion of the prism over-coated
constructions was measured four times for each, with the average
peel adhesion rating also documented in Table 6.
TABLE-US-00007 TABLE 6 Examples 21 to 33 Charge Decay, Glass
Transition Temperature, and Cross Hatch Peel Rating Amount of
Average Charge Decay Polymerizable Antistatic (seconds) CHP
(average) Onium Salt Coating DBEFII with DBEFII with Exam- (POS-1)
Thickness DBEFII with Antistatic Coating Antistatic Coating ple (wt
%) (microns) T.sub.g (.degree. C.) Antistatic Coating and Prism
Overcoat and Prism Overcoat 21 0.5 3 -14.41 14.92 14.81 0.00 22 1 3
-14.39 9.11 8.70 0.00 23 2 3 -13.28 5.77 5.07 0.00 24 5 3 -10.95
2.25 2.12 0.00 25 10 3 -9.89 0.49 0.43 0.00 26 20 3 -7.39 0.22 0.15
0.00 27 40 3 -4.29 0.18 0.05 0.00 28 45 3 -0.79 0.16 0.06 0.00 29
50 3 -0.31 0.11 0.04 0.75 30 55 3 1.72 0.18 0.05 1.75 31 60 3 3.63
0.14 0.04 1.50 32 80 3 13.45 0.14 0.06 2.50 33 90 3 20.41 0.14 0.06
2.50
[0153] Remarkably, low charge decay times persisted even at
surprisingly low concentrations of the polymerizable onium salt
with particularly useful static decay time (5 seconds) realized at
concentrations of as low as 2 wt % of the polymerizable onium salt.
This effect may be due, in part, to the lower T.sub.g seen in this
lower range of composition. At the higher levels of polymerizable
onium salt the adhesion of the prism and antistatic coating
suffered such that above 50 wt % of the polymerizable onium salt
the adhesion was compromised. The optimum compositions for the
antistatic coating in this type of optical film construction, which
effectively balances the antistatic performance with durability of
coating/prism adhesion may be from 2 wt % and 50 wt % for this
particular selection of polymerizable onium salt chemistry and
coupled with these choices for the co-acrylates in the coating
formulation.
Examples 34 to 39 and 41 and Comparative Examples C40 and C42 to
C47
[0154] In Examples 34 to 39 and 41 as well as in Comparative
Examples C40 and C42 to C47 a number of polymerizable onium salt
candidates were tested for compatibility with a specific but
representative acrylate coating formulation. The acrylate coating
mixtures in this test protocol were all based on 40 parts by weight
of polymerizable onium salt combined with the acrylate mixture
composed of 35 parts of SR 339, 25 parts of EBECRYL.TM. 8402, and
0.5 parts of the photoinitiator IRGACURE.TM. 819. The various
polymerizable onium salt chemistries tested are listed in Table
7.
[0155] Consistent with the mixing process described in previous
examples, each polymerizable onium salt described in Table 7 was
combined with the acrylate formulation into a sample bottle, sealed
with a screw cap, and subsequently heated to 60.degree. C. for 30
minutes in a convection oven. Each sample was vigorously shaken
intermittently by hand during the course of the 30 minute heating
cycle. After heating and shaking each sample was allowed to cool at
ambient conditions. Samples were held quiescently at RT conditions
for up to 2 days and then evaluated visually for homogeneity.
[0156] Solutions of Examples 34 to 39 and 41 were each homogeneous,
clear, and slightly yellow due to the photoinitiator. Comparative
Examples C40 and C42 to C47 resulted in mixtures that were
profoundly non-homogeneous as evidenced by either stratification
into liquid layers, formation of solid precipitates, or in some
cases the formation of an opaque high viscosity paste.
[0157] The experimental protocol previously described was used in
an attempt to coat and cure each formulation of this study onto
VIKUITI.TM. DBEF II. Due to the non-homogeneous nature of the
mixtures of Comparative Examples C40 and C42 to C47, these could
not be effectively processed to provide a uniform coating. However,
formulations of Examples 34 to 39 and 41 were coated successfully
onto VIKUITI.TM. DBEF II and cured to a finished thickness of
approximately 3 microns. Examples 34 to 38 provided very clear,
smooth and uniform cured coatings with very adequate charge decay
as tabulated in Table 7. The coatings from Examples 39 and 41
exhibited a very slightly streaky finish. However, these
formulations were considered to be marginally acceptable for
application into optical film constructions and also demonstrated
good charge decay.
TABLE-US-00008 TABLE 7 Examples 34 to 39 and 41, Comparative
Examples C40 and C42 to C47 Polymerizable Onium Salt Compatability
into Acrylate Coating Formulations Average Antistatic Charge
Coating Decay Exam- Quality of Coated ple Polymerizable Onium Salt
Chemistry Coating Mixture on DBEF Film (POS) Cation Anion
Characteristics II Film (seconds) 34
(CH.sub.3).sub.3--N.sup.+--(CH.sub.2CH.sub.2OC(O)CH.dbd.CH.sub.2)
.sup.-N(SO.sub.2CF.sub.3).sub.2 homogeneous clear 0.11 (POS-1)
(Acryloyloxyethyl)-N,N,N-trimethylammonium Bis(trifluoromethane
sulfonyl)imide clear solution uniform 35
(CH.sub.3CH.sub.2).sub.2--N.sup.+--(CH.sub.3)--(CH.sub.2CH.sub.2OC(O)CH-
.dbd.CH.sub.2) .sup.-N(SO.sub.2CF.sub.3).sub.2 homogeneous clear
0.06 (POS-2) (Acryloyloxyethyl)-N,N-diethyl-N-methylammonium
Bis(trifluoromethane sulfonyl)imide clear solution uniform 36
(CH.sub.3CH.sub.2).sub.2--N.sup.+--(CH.sub.3)--(CH.sub.2CH.sub.2OC(O)C(-
CH.sub.3).dbd.CH.sub.2) .sup.-N(SO.sub.2CF.sub.3).sub.2 homogeneous
clear 0.01 (POS-3) (Methacryloyloxyethyl)-N,N-diethyl-N-
Bis(trifluoromethane sulfonyl)imide clear solution uniform
methylammonium 37
(C.sub.4H.sub.9).sub.2--N.sup.+--(CH.sub.3)--(CH.sub.2CH.sub.2OC(O)CH.d-
bd.CH.sub.2) .sup.-N(SO.sub.2CF.sub.3).sub.2 homogeneous clear 0.04
(POS-4) (Acryloyloxyethyl)-N,N-dibutyl-N-methylammonium
Bis(trifluoromethane sulfonyl)imide clear solution uniform 38
(C.sub.8H.sub.17)--N.sup.+--(CH.sub.3).sub.2--(CH.sub.2CH.sub.2OC(O)CH.-
dbd.CH.sub.2) .sup.-N(SO.sub.2CF.sub.3).sub.2 homogeneous clear
0.02 (POS-8) (Acryloyloxyethyl)-N,N-dimethtyl-N-octylammonium
bis(trifluoromethane sulfonyl)imide clear solution uniform 39
(C.sub.12H25)--N.sup.+--(CH.sub.3).sub.2--(CH.sub.2CH.sub.2OC(O)CH.dbd.-
CH.sub.2) .sup.-N(SO.sub.2CF.sub.3).sub.2 homogeneous uniform 0.75
(POS- (Acryloyloxyethyl)-N,N-dimethtyl-N- Bis(trifluoromethane
sulfonyl)imide clear solution coating 14) dodecylammonium w/
streaking C40
(C.sub.16H.sub.33)--N.sup.+--(CH.sub.3).sub.2--(CH.sub.2CH.sub.2OC(O)C-
H.dbd.CH.sub.2) .sup.-N(SO.sub.2CF.sub.3).sub.2 nonhomogeneous
could not be coated (POS-9) (Acryloyloxyethyl)-N,N-dimethtyl-N-
Bis(trifluoromethane sulfonyl)imide (stratification to
hexadecylammonium two liquid layers) 41
(C.sub.4H.sub.9).sub.2--N.sup.+--(CH.sub.3)--(CH.sub.3CH.sub.2OC(O)CH.d-
bd.CH.sub.2) .sup.-C(SO.sub.2CF.sub.3).sub.3 homogeneous uniform
0.55 (POS-7) (Acryloyloxyethyl)-N,N-dibutyl-N-methylammonium
Tris(trifluoromethane clear solution coating sulfonyl)methide w/
streaking C42
(CH.sub.3).sub.3--N.sup.+--(CH.sub.2CH.sub.2OC(O)CH.dbd.CH.sub.2)
.sup.-O.sub.3SOCH.sub.3 nonhomogeneous could not be coated (POS-
(Acryloyloxyethyl)-N,N,N-trimethylammonium Methane sulfate
(stratification to 13) two liquid layers) C43
(CH.sub.3).sub.3--N.sup.+--(CH.sub.2CH.sub.2OC(O)CH.dbd.CH.sub.2)
.sup.-OSO.sub.2CF.sub.3 nonhomogeneous could not be coated (POS-
(Acryloyloxyethyl)-N,N,N-trimethylammonium Trifluoromethane
sulfonate (white paste) 10) C44
(CH.sub.3).sub.3--N.sup.+--(CH.sub.2CH.sub.2OC(O)CH.dbd.CH.sub.2)
.sup.-OSO.sub.2C.sub.4F.sub.9 nonhomogeneous could not be coated
(POS- (Acryloyloxyethyl)-N,N,N-trimethylammonium Perfluorobutane
sulfonate (stratification and 11) precipitation) C45
(C.sub.4H.sub.9).sub.2--N.sup.+--(CH.sub.3)--(CH.sub.3CH.sub.2OC(O)CH.-
dbd.CH.sub.2) .sup.-O.sub.3SOCH3 nonhomogeneous could not be coated
(POS-5) (Acryloyloxyethyl)-N,N-dibutyl-N-methylammonium Methane
sulfate (stratification to two liquid layers) C46
(C.sub.4H.sub.9).sub.2--N.sup.+--(CH.sub.3)--(CH.sub.3CH.sub.2OC(O)CH.-
dbd.CH.sub.2) .sup.-OSO.sub.2CF.sub.3 nonhomogeneous could not be
coated (POS-6) (Acryloyloxyethyl)-N,N-dibutyl-N-methylammonium
Trifluoromethane sulfonate (solid precipitate) C47
(C.sub.4H.sub.9).sub.2--N.sup.+--(CH.sub.3)--(CH.sub.3CH.sub.2OC(O)CH.-
dbd.CH.sub.2) .sup.-OSO.sub.2C.sub.4F.sub.9 nonhomogeneous could
not be coated (POS- (Acryloyloxyethyl)-N,N-dibutyl-N-methylammonium
Perfluorobutane sulfonate (white paste) 12)
Example 48
[0158] An antistatic coating formulation was prepared by mixing 40
parts by weight of polymerizable onium salt
acryloyloxyethyl-N,N,N-trimethylammonium
bis(trifluoromethanesulfonyl)imide (POS-1), 35 parts by weight of
SR 339, 25 parts by weight of EBECRYL.TM. 8402, and 0.5 parts by
weight of IRGACURE.TM. 819 photoinitiator. This formulation was
coated and cured onto conventional 5 mil (127 micron) biaxially
oriented adhesion-primed PET film MELINEX.TM. 618, from DuPont
Teijin Films (Hopewell, Va.). One specimen was prepared at each of
the four coat thicknesses of 1, 2, 3, and 4 microns. Mixing of the
formulation as well as the coating and cure of the formulation onto
the primed surface of the 5 mil (127 micron) PET was accomplished
using equipment and experimental protocol as described in Examples
1 to 12. The samples were also over coated with 90/50 BEF prisms
using procedures and materials described in Examples 1 to 12.
Charge decay before and after over coating with BEF prisms as well
as the average cross hatch peel of the prism coated construction
are shown in Table 8.
TABLE-US-00009 TABLE 8 Example 48 PET Film Charge Decay and Cross
Hatch Peel Adhesion Rating Average Charge Decay CHP (average)
Antistatic (seconds) PET Film with Coating PET Film with PET Film
with Antistatic Coating Thickness Antistatic Antistatic Coating and
Prism (microns) Coating and Prism Overcoat Overcoat 1 0.32 1.00 0 2
0.25 0.56 0 3 0.15 0.31 0 4 0.13 0.24 0.5
Examples 49 to 54
[0159] A series of antistatic coating formulations were prepared by
mixing 40 parts of polymerizable onium
acryloyloxyethyl-N,N,N-trimethylammonium
bis(trifluoromethanesulfonyl)imide, with 60 parts of selected
multi-functional acrylates. Each formulation featured a single
multifunctional acrylate as listed in Table 9 and 0.5 parts of
IRGACURE.TM. 819 photoinitiator (no non-onium monofunctional
acrylates were used). As per procedures described in previous
examples, these mixtures were each heated to 60.degree. C. for
approximately 30 minutes in sealed sample bottles, shaken
vigorously by hand to mix, and finally allowed to cool at ambient
conditions. At room temperature all the solutions were homogeneous,
clear, slightly yellow due to the photoinitiator.
[0160] Formulations of Examples 49 to 54 were coated and cured onto
VIKUITI.TM. DBEF II using the same procedures and apparatus as
outlined above with the exception that the formulation of Example
49 was diluted with 20 parts by weight of isopropyl alcohol (IPA)
in order to decrease the viscosity and facilitate coating at room
temperature. The IPA was dried from the coated specimen of Example
49 during the standard 30 second preheat on the 140.degree. F.
(60.degree. C.) platen just prior to cure. Coating thickness for
each formulation of Examples 49 to 54 was 3 microns. Overcoat of
the cured 3 micron antistatic coatings with 90 degree 50 pitch BEF
prisms was completed under the same experimental protocol
previously described.
[0161] Table 9 documents the glass transition temperatures of the
cured antistatic formulations. The glass transition temperatures of
formulations of Examples 50 and 51 could not be determined with the
standard DSC technique described previously, as the transition was
too broad and diffuse to be distinguished from the specimen
thermogram. For comparative purposes the glass transition of the
constituent commercial acrylates as published by their
manufacturers is also documented in Table 9. The charge decay of
the 3 micron coating formulations on VIKUITI.TM. DBEF II, and the
charge decay of the specimens after overcoating with the BEF prism
structure were measured and documented. In addition, the peel
adhesion ratings of the prism over-coated constructions were each
measured four times with the average peel adhesion rating also
documented in Table 9.
TABLE-US-00010 TABLE 9 Examples 49 to 54 Single Multi-Functional
Acrylate Mixed with Polymerizable Onium Salt (POS-1) Charge Decay,
Glass Transition Temperature, and Cross Hatch Peel Rating Average
Charge Decay (seconds) CHP (average) Antistatic DBEFII with DBEFII
with Commercial Multi-Functional Acrylate Coating DBEFII with
Antistatic Antistatic Exam- Trade Acrylate Published (40% POS)
Antistatic Coating and Coating and ple Name Description
Functionality T.sub.g (.degree. C.) T.sub.g (.degree. C.) Coating
Prism Overcoat Prism Overcoat 49 EBECRYL Aliphatic Urethane
Diacrylate 2 14 35.4 36.6 1.03 3 8402 50 SR 494 Emoxylated.sub.4
Pentaerythritol 4 2 Transition 55.3 >100 3 Tetraacrylate too
broad 51 SR 454 Ethoxylated.sub.3 Trimethylolpropane 3 40 to 83.3
>100 3 Triacrylate determine 52 CD 561 Alkoxylated Hexanediol 2
-38 3.5 0.09 0.03 2 Diacrylate 53 CD 9038 Ethoxylated.sub.30
Bisphenol A 2 -42 -24.2 0.01 0.01 2 Diacrylate 54 SR 9035
Ethoxylated.sub.15 3 -32 -2.9 0.04 0.03 3 Trimethylolpropane
Triacrylate
[0162] These results clearly show that antistatic performance was
shown by effective acrylate coatings based on the simpler
combination of polymerizable onium salts with a single
multi-functional acrylate. Further, the charge decay was still
correlated to a great extent to the glass transition of the cured
coating. Although the actual value was not available from Examples
50 and 51, the higher T.sub.g of these three may be inferred from
the published T.sub.g of the constituent multi-functional
acrylates. Furthermore, the coatings of Example 50 and 51 were
discernibly higher modulus (harder to the touch) than the
counterparts of Examples 52, 53, and 54, which suggests they
possessed higher T.sub.g.
Examples 55 to 58
[0163] An antistatic coating formulation was prepared by mixing 40
parts of polymerizable onium salt
acryloyloxyethyl-N,N,N-trimethylammonium
bis(trifluoromethanesulfonyl)imide, 35 parts SR 339, 25 parts
EBECRYL.TM. 8402, and 0.5 parts by weight of IRGACURE.TM. 819
photoinitiator using standard mixing protocol described above. This
formulation was then diluted with an equal portion of isopropanol
(IPA) to form a 50% solids solution for coating. This recipe was
then coated onto VIKUITI.TM. DBEF II using the laboratory scale
multi-roll coater as described above. Just after coating each
specimen was immediately heated in a 140.degree. F. (60.degree. C.)
convection oven for 2 minutes to dry the IPA from the coating. This
step was provided in substitution for the platen heating step used
to preheat 100% solids coated samples just prior to UV cure. Cure
of the dried acrylate coating on DBEF II was then accomplished via
standard protocol using a UV processor. The coating thickness was
adjusted via the amount of coating solution delivered to the
multi-roll coater to yield the specimens for Examples 55 to 58 at a
dried and cured coating thickness of 0.25, 0.50, 1.0 and 2.0
microns, respectively. Each of the samples was also over coated
with BEF prisms. Charge decay before and after over coating with
BEF prisms as well as the average cross hatch peel of the prism
coated construction are shown in Table 10.
TABLE-US-00011 TABLE 10 Coating Thickness Study on DBEF II Charge
Decay and Cross Hatch Peel Rating Average Charge Decay (seconds)
CHP (average) Antistatic DBEF II with DBEF II with Coating DBEF II
with Antistatic Antistatic Thickness Antistatic Coating and Coating
and Example (microns) Coating Prism Overcoat Prism Overcoat 55 0.25
1.83 2.11 1.5 56 0.50 0.64 1.25 1.5 57 1.0 0.18 0.50 1 58 2.0 0.17
0.22 1
[0164] Although the present invention has been fully described in
connection with the preferred embodiments thereof with reference to
the accompanying drawings, it is to be noted that various changes
and modifications are apparent to those skilled in the art. Such
changes and modifications are to be understood as included within
the scope of the present invention as defined by the appended
claims unless they depart therefrom.
[0165] A number of patents and patent applications are referred to
herein; each is incorporated by reference in its entirety.
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