LIGHT MANAGEMENT FILM AND ITS PREPARATION AND USE
BACKGROUND OF THE INVENTION
Light management films are widely used in backlight display devices, such as the flat
panel displays of laptop computers. They are used to control the light intensity of the
display as a function of viewing angle. Light management films comprising a
thermoplastic base layer, such as polycarbonate or polyethylene terephthalate, and a
microstrucrured prismatic layer are known. However, handling of such light
management films during device fabrication causes accumulation of static energy,
which in turn leads to dust attraction. Dust build-up on the film increases device
manufacturing time, decreases device yield, and compromises device appearance.
Further, flat panel displays, for example, employ a plurality of films arranged in a
manner to obtain the desired brightness and diffusion of the light directed to the
viewer. It is noted that as the number of films employed increases, the over thickness
of the display increases.
Since a demand exists for increasingly thinner flat panel display devices, what is
needed in the art is a multifunctional light management film, as well as a light
management films with improved anti-static, anti-dust properties.
BRIEF DESCRIPTION OF THE INVENTION
The above-described and other drawbacks are alleviated by a light management film,
comprising:
a first layer comprising
a thermoplastic resin selected from aromatic polycarbonates, polyetherimides,
polyesters, polyphenylene ethers, polyphenylene ether/styrene polymer blends,
polyamides, polyketones, acrylonitrile-butadiene-styrenes, and blends thereof, and
a phosphonium sulfonate salt haying the structure
(Figure Removed)
wherein each occurrence of X is independently halogen or hydrogen provided that at
least one X is halogen; m, p, and q are integers from 0 to 12; n is 0 or 1 with the
proviso that when n is 1, p and q are not both 0; R'-R3 are each independently Ci-Cu
hydrocarbyl; R4 is Ci-C|g hydrocarbyl; and Y is selected from
(Figure Removed)
wherein R5 is hydrogen or Ci-Ci: hydrocarbyl; and
a second layer disposed on a face of the first layer; wherein the second layer is the
cured product of a curable composition; and wherein the second layer has an index of
refraction of at least 1.5.
Other embodiments, including a method of preparing the light management film and a
flat panel display comprising the light management film are described in detail below.
BRIEF DESCRIPTION OF THE DRAWINGS
Referring now to the drawings wherein like elements are numbered alike in several
FIGURES:
FIG. 1 is a schematic cross-sectional view of a segment of a light management film 1
.comprising a first layer 10 and a second layer 20; and
FIG. 2 is a schematic cross-sectional view of a segment of a light management film 1
comprising a first layer 10, a second layer 20, a first masking layer 30, and a second
masking layer 40.
DETAILED DESCRIPTION OF THE INVENTION
The present inventors have conducted extensive research on the methods of reducing
the static electricity build-up and dust attraction of light management films. They
have surprisingly discovered that incorporation of a particular type of phosphonium
sulfpnate salt into the thermoplastic first (base) layer dramatically improves the antistatic
and anti-dust properties of the film, even though the phosphonium sulfonate salt
is not added to the second (cured) layer. Incorporation of the phosphonium sulfonate
salt reduces the surface resistivity of the thermoplastic base layer by up to four orders
of magnitude or more, and reduces the static decay half-life of the entire lightmanagement
film by up to three orders of magnitude or more.
;Th.e light management film comprises a first layer that includes a thermoplastic resin.
Suitable thermoplastic resins include, for example, aromatic polycarbonates,
polyetherimides, polyesters, polyphenylene ethers, polyphenylene ether/styrene
polymer blends, polyamides, polyketones, acrylonitrile-butadiene-styrenes, and blends
thereof. In one embodiment, the thermoplastic resin comprises an aromatic
polycarbonate. The first layer may comprise the thermoplastic resin in an amount of
about 50 to about 99.99 weight percent, based on the total composition of the first
layer. Within this range, the thermoplastic resin amount may specifically be at least
about 90 weight percent, more specifically at least about 95 weight percent, still more
specifically at least 98 weight percent.
In addition to the thermoplastic resin, the first layer includes a phosphonium sulfonate
salt that contributes anti-static properties. Suitable phosphonium sulfoiiate salts
include those having the structure
(Figure Removed)
wherein each occurrence of X is independently halpgen or hydrogen provided that at
least one X is halogen; m, p, and q are integers from 0 to 12; n is 0 or 1 with the
proviso that when n is 1, p and q are not both 0; R'-R3 are each independently C|-Ci2
hydrocarbyl; R4 is C|-C|8 hydrocarbyl; and Y is selected from
(Figure Removed)
wherein R5 is hydrogen or Ci-Cu hydrocarbyl. As used herein, the term
"hydrocarbyl", whether used by itself, or as a prefix, suffix, or fragment of another
term, refers to a residue that contains only carbon and hydrogen. The residue may be
aliphatic or aromatic, straight-chain, cyclic, bicyclic, branched, saturated, or
unsaturated. It may also contain combinations of aliphatic, aromatic, straight chain,
cyclic, bicyclic, branched, saturated, and unsaturated hydrocarbon moieties. The
hydroearbyl residue, when so stated however, may contain heteroatoms over and
above the carbon and hydrogen members of the substituent residue. Thus, when
specifically noted as containing such heteroatoms, the hydrocarbyl or hydrocarbylene
residue may also contain carbonyl groups, amino groups, hydroxyl groups, or the like,
or it may contain heteroatoms within the backbone of the hydrocarbyl residue. As
used herein, the term "halogen" includes fluorine, chlorine, bromine, and iodine.
In one embodiment, the phosphonium sulfonate salt has the structure above, wherein
n, p, and q are zero, and m is ,1 to 12. Thus, the phosphonium sulfonate salt has the
structure
wherein each occurrence of X is independently halogen or hydrogen provided that at
least one X is halogen; R'-R3 are each independently Ci-Ci2 hydrocarbyl; and R4 is
Ci-Ci8 hydrocarbyl.
In one embodiment, the phosphonium sulfonate salt is a fluorinated phosphonium
sulfonate salt and is composed of a fluorocarbon containing an organic sulfonate
anion and an organic phosphonium cation. Examples of such fluorinated organic
sulfonate anions include perfluoro methane sulfonate, perfluoro butane iulfonate,
perfluoro hexane sulfonate, perfluoro heptane sulfonate, perfluoro octane sulfonate,
and the like. Examples of the aforementioned organic phosphonium cation include
aliphatic phosphonium cations such as tetramethyl phosphonium, tetraethyl
phosphonium, tetrabutyl phosphonium, triethylmethyl phosphonium, tributylmethyl
phosphonium, tributylethyl phosphonium, trioctylmethyl phosphonium, trimethylbutyl
phosphonium, trimethyloctyl phosphonium, trimethyllauryl phosphonium,
trimethylstearyl phosphonium, triethyloctyl phosphonium; and aromatic .phosphonium
cations such as tetraphenyl phosphonium, triphenylmethyl phosphonium,
triphenyibenzyl phosphonium, tributylbenzyl phosphonium; and the like.
, The phosphonium sulfonate salt can be .obtained by any combination of any of these
organic sulfonate anions and organic cations but is not limited by the examples given
. above. Fluorinated phosphonium sulfonate salts may be produced in a very pure form
by mixing the corresponding sulfonic acid and the quaternary phosphonium hydroxide
in a solvent mixture followed by evaporation of the solvent mixture. Tetrabutyl
phosphonium perfluoro butane sulfonate, for example, can be produced with a yield of
about 95% by placing 98.6 grains (g) of perfluoro butane sulfonic acid, 200 milliliters
(mL) of a 40 weight percent solution of tetrabutyl phosphonium hydroxide, and 500
mL of a solvent mixture in a flask, stirring the mixture for one hour at room
temperature, isolating phosphonium sulfonate, which separates as an oily layer,
washing it with 100 mL of water, and evaporating the solvents using a vacuum pump.
In one embodiment, the phosphonium sulfonate salt comprises tetra-nbutylphosphonium
noriafluoro-n-butylsulfonate (tetrabutylphosphonium
1,1,2,2,3,3.4,4,4-nonafluoro-l-butanesulfonate; Chemical Abstracts Service Registry
No! 220689-12-3). ,
The phosphonium sulfonate salt may be used in an amount effective to improve the
anti-static properties of the light management film. Such amounts are generally about
0.00001 to about.2 weight percent, based on the total composition of the first layer.
Within this range, the phosphonium sulfonate salt amount may specifically be at least
0.001- weight percent, more specifically at least 0,1 weight percent, still more
specifically at least 0.2 weight percent. Also within this range, the phosphonium
sulfonate salt amount may specifically be up to 1.5 weight percent, more specifically
up to 1 weight percent.
In one embodiment, the light management film is substantially free of fluorinated
compounds other than fluorinated phosphonium sulfonate salts. It may be desirable to
minimize the content of halogenated compounds in order to improve the
environmental friendliness of the light management film.
The first layer may generally have a thickness of about 25 to about 300 micrometers,
Within this range, the thickness may specifically be at least about 50 micrometers,
more specifically at least 100 micrometers. Also within this range, the thickness may
specifically be up to about 250 micrometers, more specifically up to 200 micrometers.
In addition to the first layer, the light management film comprises a second layer
disposed on a face of the first layer. The second layer has an index of refraction of at
. least 1.5, more specifically at least about 1.61. The second layer is the cured product
of a curable composition. The curable composition generally comprises a
polymerizable compound. Polymerizable compounds, as used herein, are monomers
or.oligomers comprising one or more functional groups capable of undergoing radical,
cationic, anionic, thermal, or photochemical polymerization. Suitable functional
groups include, for example, acrylate, methacrylate, vinyl, epoxide, and the like.
In one embodiment, the curable composition comprises an alkane diol
. di(meth)acrylate having 2 to about 12 carbon atoms in the alkane moiety. As used
herein, the fragment -(meth)acryl- includes -acryl-, -methacryl-, -thioacryl-
(CH2=CH2-C(=O)-S-), and -thiomethacryl- (CH2=CH(CH3)-C(=O)-S-). Suitable
alkane diol di(meth)acrylates include, for example, ethylene glycol di(meth)acrylate,
1,4-butane diol di(meth)acrylate, 1,6-hexane diol di(meth)acrylate, 1,8-octane diol
diacrylate, 1,10-decane diol diacrylate, and the like, and mixtures thereof. In one
embodiment, the alkane diol di(meth)acrylate comprises 1,6-hexane diol
di(meth)acrylate.
In' 'one embodiment, the curable composition comprises a multifunctional
(meth)acrylate having the structure
wherein R6 is hydrogen or methyl; X1 is O, NH, or S; R7 is substituted or
unsubstituted Ci-Cioo hydrocarbyl having a valence of r; and r is 2, 3, or 4. The
substitution on R7 may include fluorine, chlorine, bromine, iodine, C\-C(, alkyl, Q-Cs
perhalogenated alkyl, hydroxy, C\-C<, ketone, Ci-C6 ester, N,ISI-(C|-C3) alkyl
substituted amide, or the like, or a combination thereof.
In one embodiment, the curable composition comprises a difunctional (meth)acrylate,
an arylether (meth)acrylate, and a polymerization initiator.
The difunctional (meth)acrylate may have the structure
wherein R6 is hydrogen or methyl; X1 is O, NH, or S; and R8 has the structure
wherein Q is -C(CH3)2- -CH2- -C(O)-, -0-, -S-, -S(O>-, or-S(O)2-; R9 is d-C6
alkylene or hydroxy-substituted Ci-C6 alkylene; each occurrence oft is independently
0, 1, 2, 3, or 4; and d is 1 to 3. Suitable difunctional (meth)acrylates include, for
example, 2,2-bis(4-(2-(meth)acryloxyethoxy)phenyl)propane; 2,2-bis((4-
(meth)acryloxy)phenyl)propane; (meth)acrylic acid 3-(4-{l-[4-(3-acryloyloxy-2-
hydroxy-propoxy)-3,5,-dibromo-phenyl]-l-methyl-ethyl}-2,6-dibromo-phenoxy)-2-
hydroxy-propyl ester; (meth)acrylic acid 3-[4-(l-{4-[3-(4-{l-[4-(3-acryleyloxy-2-
hydroxy-propoxy)-3,5-dibromo-phenyl]-l-methyl-ethyl}-2,6-dibromo-phenoxy)-2-
hydroxy-propoxy]-3,5-dibromo-phenyl}-l-methyl-ethy])-2,6-dibromo-phenoxy]-2-
hydroxy-propyl ester; and the like, and combinations thereof. The difunctional
(meth)acrylate may be .prepared, for example, by reacting a brominated bisphenol with
epichlorohydrin to form ah epoxide copolymer, which is then reacted with
(meth)acrylic acid to produce the difunctional (meth)acrylate. Difunctional
(meth)acrylates are also commercially available as, for example, the multifunctional
(meth)acrylate based on the reaction product of tetrabrominated bisphenol-A diepoxide
available as RDX 51027 from UCB Chemicals. Additional commercially
available multifunctional epoxides include, for example, EB600, EB3600, EB3700,
EB3701, EB3702, and EB3703, all available from UCB Chemicals, as well as CN104
and CN120 available from Sartomer. The difunctional (meth)acrylate may be present
in an amount of about 10 to about 90 weight percent based on the total curable
composition. V/ithin this range, the difunctional (meth)acrylate amount may
specifically be at least about 35 weight percent, more specifically at least about 45
weight percent, even more specifically at least about 50 weight percent. Also within
this range, the difunctional (meth)acrylate amount may specifically, be up to about 70
weight percent, more specifically ;up to about 65 weight percent,, even more
specifically up to about 60 weight percent.
The arylether (meth)acrylate may have the structure
wherein R6 is hydrogen or methyl; X1 is 0, NH, or S; X2 is O, NH, or S; R10 is
substituted or unsubstituted divalent C|-Ci2 alkylene or alkenylene; Ar is substituted
or unsubstjruted C6-C|2 aryl, including phenyl; wherein the substitution on the R10 and
Ar may independently include fluorine, chlorine, bromine, iodine, C\-C(, alky], C\-C$
perhalogenated alkyl, hydroxy, C|-C6 ketone, C|-Ce ester, N,N-di(Ci-C3)alkyJamide,
or a combination comprising at least one of the foregoing substituents. The Ar group,
when substituted, may be mono-, di-, tri-, tetra- or penta-substituted. As used herein,
"arylether" 'is inclusive of both arylethers and arylthioethers, also known as
arylsulfides. In one embodiment, X2 is S. In one embodiment; the arylether
(meth)acrylate comprises 2-phenoxyethyl (meth)acrylate, 2-phenylthioethyl
(meth)acrylate, or a combination thereof. Methods of preparing arylether
(meth)acrylates are known in the art. For example, the synthesis of 2-phenoxyethyl
niethacrylate is described in U.S. Patent Nos,5;498,751 to Trapasso et al, and
6,714,712 to Bishop et al. Arylether methacrylates are also commercially available.
For example, phenylthioethyl acrylate is available as BX-PTEA from Bimax
Company, and 2-phenoxyethyl acrylate is available as SR339 from Sartomer. The
arylether (meth)acrylate is present in an amount of about 15 to about 70 weight
percent based on the total curable composition. Within this range, the arylether
(meth)acrylate amount may specifically be at least about 20 weight percent, more
specifically at least about 30 weight percent. Also within this range, the arylether
(meth)acrylate amount may specifically be up to about 60 weight percent, more
^specifically up to about 50 weight percent, even more specifically up to about 40
weight percent.
Suitable polymerization initiators and ampunts are discussed below.
In another embodiment, the curable coating comprises a difunctional (meth)acrylate,
an arylether (meth)acrylate, a brominated aromatic (meth)acrylate, and a
polymerization initiator. The difunctional (meth)acrylate and the arylether
(meth)acrylate are the same as those described above. The brominated aromatic
(meth)acrylate may have the structure
wherein R6 is hydrogen or methyl; X1 is O, NH, or S; X3 is O, NH, or S; r is 0,1, 2, or
3, and s is 0 or 1, with the proviso that if r is 0 then s is 0; and u is 3, 4, or 5. Suitable
brominated aromatic (meth)acrylates include, for example, 2,4,6-tribromobenzyl
(meth)acrylate, tetrabromobenzyl (meth)acrylate, tribromophenyl (meth)acrylate,
pentabromophenyl (meth)acrylate, and pentabromobenzyl (meth)acrylate. Methods of
.preparing brominated aromatic (meth)acrylates are known in the art. For example,
preparations of various brominated benzyl (meth)acrylates are described in U.S.
Patent No. 4,059,618 to Blumenfeld et al. Brominated aromatic (meth)acrylates are
also commercially available. For example, pentabromobenzyl acrylate is available as
FR1025M from Ameribrom. The amounts of the difunctional (meth)acrylate, and the
arylether (meth)acrylate may be the same as those discussed above: The amount of
the brominated aromatic (rneth)acrylate may be about 1 to about 20 weight percent
based on the total curable composition. Within this range, the brominated aromatic
(meth)acrylate amount may specifically be at least about 3 weight percent, more
specifically at least about 4, even more specifically at least about 5 weight percent.
Also within this range, the brominated aromatic (meth)acrylate amount may
specifically be up to about 15 weight percent, more specifically up to about 10 weight
percent, even more specifically up to about 8 weight percent.
In another embodiment, the curable composition comprises a high refractive index
monomer having the structure
wherein Z is an ethylenically unsaturated group; X4 is 0, S, or NH; L1 and L2 are each
independently C|-C2 alkylene, -(C|-C3 alkylene)-S-(Ci-C3 alkylene)-, or -(CrCa
; alkylene)-O-(C(-C3 alkylene)-; R" is hydrogen or CrC6 alkyl; R12 and R13 are each
independently aryl, including phenyl or naphthyl, aryl(Ci-C6 alkylene)-, heteroaryl, or
heterbaryl(C|-C6 alkylene)-, each of which group is substituted with 0 to 5
substituents independently chosen from halogen, C|-C4 alkyl, C\-C« alkoxy, (C|-C4
alkyl)S-, Ci-C4 haloalkyl, and C|-C4 haloalkoxy; and Y1 and Y2 are each
independently O, S, NH, or N. In one option of this embodiment, Y1 and Y2 are both
S, and i) X4 is S, or ii) at least one of R12 and R13 is heteroaryl or heteroaryl(C|-C6
alkylene) substituted as previously described; or iii) one or both of L1 and L2 are -(Ci*
C3 alkylene)-S-(C|-C3 alkylene)-, or -(C|-C3 alkylene)-0-(CrC3 alkylene)-. In another
option of this embodiment, Y1 or Y2 is N, and each corresponding combination RI2-Y*
or RI3-Y2 is independently an N-containing heteroaryl excluding carbazole. In
another option of this embodiment, Z is acryloyl, methacryloyl, vinyl, or ally!; X is O
or S; and R is hydrogen. "High refractive index monomer" refers to a monomer that
may contribute increased refractive index to cured compositions comprising it.
Additional high refractive index monomers and curable compositions comprising
them are described copending U.S. Serial No. [attorney docket number 134434-7
filed 7-21-04], filed July 21, 2004.
The curable compositions described above comprise a polymerization initiator to
promote polymerization of the curable components. Suitable polymerization initiators
include photoinitiators that promote polymerization of the components upon exposure
to ultraviolet radiation. Particularly suitable photoinitiatprs include phosphine oxide
photoinitiators. Examples of such photoinitiators include the IRGACURE® and
DAROCUR® series of phosphine oxide photoinitiators available from Ciba Specialty
Chemicals; the LUCIRIN® series from BASF Corp.; and the.ESACURE® series of
photoinitiators available from Lamberti. Other useful photoinitiators include ketonebased
photoinitiators, such as hydroxyalkyl phenyl ketones and alkoxyalkyl phenyl
ketones, and thioalkylphenyl morpholinoalkyl ketones. Also suitable are benzoin
ether photoinitiators. Combinations of the foregoing photoinitiators may be used.
The polymerization initiator may include peroxy-based initiators that promote
polymerization under thermal activation. Examples of useful peroxy initiators
include, for example, benzoyl peroxide, dicumyl peroxide, methyl ethyl ketone
peroxide, lauryl peroxide, cyclohexanone peroxide, t-butyl hydroperoxide, t-butyl
benzene hydroperoxide, t-butyl peroctoate, 2,5-dimethylhexane-2,5-dihydroperoxide,
2,5-dimethyl-2,5-di(t-butylpercxy)-hex-3-yne, di-t-butylperoxide, t-butylcumyl
peroxide, alpha,alpha'-bis(t-butylperoxy-m-isopropyl)benzene, 2,5-dimethyl-2,5-iii(tbutylperoxy)
hexane, dicumylperoxide, di(t-butylperoxy) isophthalate, tbutylperoxybenzoate,
2,2-bis(t-butylperoxy)butane, 2,2-bis(t-butylperoxy)octane, 2,5-
dimethyl-2,5-di(benzoylperoxy)hexane, di(trimethylsilyl)perpxide,
trimethylsilylphenyltriphenylsilyl peroxide, and the like, and combinations thereof.
The polymerization initiator may be used in an amount effective to promote curing of
the curable composition. For example, the polymerization initiator may be used in an
amount of about 0.01 to about 10 weight percent based on the total weight of the
composition. Within this range, it may be preferred to use a polymerization initiator
amount of at least about 0.1 weight percent, more preferably at least about 6.5'weight
percent. Also within this range; it may be preferred to use a: polymerization initiator
amount of up to about 3 weight percent, more preferably up to about 1 weight percent.
Other suitable curable compositions include those describe in commonly assigned
U.S. Application Serial No. 10/336,493, filed January 6, 2003.
The second layer has a refractive index of at least 1.5, more specifically at least 1.61,
still more specifically at least 1,63, The refractive index of the second layer may be
increased by including in the curable composition metal oxide nanoparticles. Suitable
metal oxide nanoparticles and methods for their preparation are described, for
example, in U.S. Patent Nos. 6,261,700 Bl to Olson et al., 6,291,070 Bl to Arpac et
al.i as well as commonly ^assigned, co-pending U.S. Serial No. 10/652,812. For
example, metal oxide nanoparticles may be prepared by a method comprising:
hydrolyzing metal alkoxide with an acidic alcohol solution, wherein the acidic alcohol
solution comprises an alkyl alcohol, water, and an acid to form a first sol comprising
metal oxide nanoparticles; treating the first sol with an organosilane to form a second
sol comprising treated metal oxide nanoparticles; and treating the second sol with an
organic base in an amount of about 0.1:1 to about 0.9:1 molar ratio of organic base to
acid to form a third sol comprising treated metal oxide nanoparticles. The metal of
the metal alkoxide may be, for example, titanium, cerium, zirconium, or tin. The
alkoxide of the metal alkoxide may be, for example, a linear or branched Ci-Cu
alkoxide.
The glass transition temperature of the cured resin obtaining on curing the curable
composition may be at least about 35°C, specifically at least about 40°C. The cured
resin also may have one or more of the following properties: a tensile strength of
about 70 to about 700 kilograms per square-centimeter (kg/cm2); a modulus of
elasticity of about 140 to about 14,000 kg/cm2; an elongation to break of about 5 to
about 300 percent; a transmittance of at least about 91%; a haze value less than about
5%; and a birefringence of less than or equal to about 0,002. Both transmittance and
haze may be measured on a hazemeter on samples having cured coating thicknesses of
about 10 to about 30 micrometers.
The curable composition may, optionally, further comprise an additive selected from
flame retardants, antioxidants, thermal stabilizers, ultraviolet stabilizers, dyes,
colorants, anti-static agents^ surfactant, arid the like, and combinations thereof, so long
as they do not deleteriously affect the polymerization of the composition or the
properties of the second layer.
The second layer may have a thickness of at about 10 to about 100 micrometers.
Within this range, the second layer thickness may specifically be at least about 20
micrometers, more specifically at least about 35 micrometers. Also within this range,
the second layer thickness may specifically be up to about 80 micrometers, more
specifically up to about 60 micrometers.
For protection and convenience of handling in between preparation of the light
management layer and its incorporation into a device, the light management layer may
comprise one or more masking layers in addition to the first layer and the'second
layer. For example, the light management layer may comprise a masking layer
disposed on a surface of the first layer opposite the second layer, and/or a masking
layer disposed on a surface of the second layer opposite the first layer. Suitable
masking layers include single or coextruded layers of polyethylene, polypropylene,
polyester or combinations thereof where the adhesion to the first or second layer is
controlled either by pressure sensitive adhesive or static.
One embodiment is a light management film, comprising:
a first layer comprising
an aromatic polycarbonate, and
a phosphonium sulfonate salt having the structure
(Figure Removed)
wherein each occurrence of X is independently halogen or hydrogen provided that at
least one X is halogen; R'-R3 are each independently C|-C|2 hydrocarbyl; and R4 is
Cj-C|g hydrocarbyl; and .
a second layer disposed on a face of the first layer; wherein the second layer has an
index of refraction of at least 1.5; and wherein the second layer is the cured product of
a curable composition comprising a multifunctional (meth)acrylate having the
structure
(Figure Removed)
wherein R6 is hydrogen or methyl; X1 is O, NH, or S; R7 is substituted or
unsubstituted Ci-Ciob hydrocarbyl having a valence of r; and r is 2, 3, or 4.
Another embodiment is a light management film, comprising:
a first layer comprising •
an aromatic polycarbonate, and .
tetra-n-butylphosphonium nonafluoro-n-butylsulfonate; and
a second layer disposed on a face of the first layer; wherein the second layer has an
index of refraction of at least 1.61; and wherein the second layer is the cured product
of a curable composition comprising
a difunctional (meth)acrylate having the structure
wherein R6 is hydrogen or methyl; X1 is O, NH, or S; and R8 has the structure
(Figure Removed)
wherein Q is -C(CH3)2- -CH2-, -O-,' -S-, C(OH -8(0)-, or -S(O)r-; R9 is CrC6
• alkylene or hydroxy-substituted Ci-C6 alkylene; each occurrence oft is independently
0,1,2, 3, or 4; and d is 1 to 3;
an arylether (meth)acrylate having the structure
wherein R6 is hydrogen or methyl; X1 is 0, NH, or S; X2 is O, NH, or S; R10 is
substituted or unsubstituted divalent Ci-Cn a'lkylene or alkenylene; Ar is substituted
or unsubstituted C6-C|2 aryl, including phenyl; wherein the substitution on the Rloand
Ar may independently include fluorine, chlorine, bromine, iodine, C\-C(, alkyl, C\-C^
perhalogenated alkyl, hydroxy, C|-C6 ketone, C\-C(, ester, N,N-di(Ci-C3)alkylamtde,
or a combination comprising at least one of the foregoing substituents; and
a polymerization initiator. ., .
In one embodiment, the second layer bears a microstructured pattern on the surface
opposite the first layer. More particularly, the first layer (base film) comprises a first
surface (i.e., the surface of the first layer that faces toward a LCD when employed.in a
flat panel display, more particularly the surface of the first layer that faces toward the
user of the device) and a second surface (i.e., the surface that faces toward the light
guide, more particularly the surface that faces away from the user of the device),
wherein, the second layer is disposed in physical communication with the first surface
of the first layer.
In an embodiment, the first layer comprises a second surface, which, can comprise a
polished surface or a textured surface (e.g., a matte surface, velvet surface, .and the
like). It is noted that when a textured second surface is employed in a laptop
computer, the overall thickness of the films employed can advantageously be
decreased by at least the thickness of a light diffusing film. More particularly, the
overall thickness can be decreased by greater than or equal to about 50 micrometers,
more specifically greater than or equal to about 100 micrometers. ,
The terms "polish", "matte", and "velvet" are all terms readily understood by those
skilled in the art. For example, a polish surface can comprise a surface roughness
(Ra) of less than 0.3 micrometers; a matte (e.g., fine matte, medium matte, course
matte, and the like) surface can comprise a surface roughness (Ra) of 0.3 micrometers
to 2.2 micrometers; and a velvet surface can comprise a surface roughness (Ra)
greater than 2.2 micrometers. It is noted that the term surface roughness (Ra) is a term
.readily understood by those skilled in the art. Generally, the Ra is a measure of the
average roughness of the film. It can be determined by integrating the absolute value
of the difference between the surface height and the average height and dividing by
the measurement length for a one dimensional surface profile, or the measurement
area for a two dimensional surface profile. More particularly, surface roughness can
be measured using a Serfcorder SE4000K, commercially available from Kosaka
Laboratory Ltd., wherein the surface roughness is measured according to ASME
B46.1-1995.
Further, the first layer of the light management film can comprise a haze value
sufficient to eliminate at least one light-diffusing film (e.g., a bottom light diffusing
film) in a display device. In other words, the light management film can b<5 a
multifunctional film, acting to direct light along a viewing axis (i.e., an axis normal
: (perpendicular) to the display), and as a light diffusing film. The terms "top" and
"bottom" used herein with regards to light-diffusing films, as well as any other film
employed in a display device, e.g., a backlight display device, are readily understood
by those skilled in the art. The term "top" generally refers to a side of a film or the
film itself that is closest to the LCD (i.e., the side or the film itself that is closest to
and/or faces toward the viewer). Conversely, the term "bottom" generally refers to a
side of a film or the film itself that is farthest away from the LCD (i.e., the side of the
film itself that is farthest away from and/or faces away from the viewer). For
example, the first layer can comprise a haze value of about 20% to about 80%.
It is noted that the percent haze can be predicted and calculated from the following
equation:
Transmission
Total Transmission
wherein total transmission is the integrated transmission; and the .total diffuse
transmission is the light transmission that is scattered by the film as defined by ASTM
D1003.
One embodiment of a method of preparing a light management film, comprises:
coating a curable composition on a surface of a substrate; wherein the substrate
comprises
a thermoplastic resin selected from aromatic polycarbonates, polyetherimides,
polyesters, polyphenylene ethers, polyphenylene ether/styrene polymer blends,
polyamides, polyketones, acrylonitrile-butadiene-styrenes, and blends thereof; and
a phosphonium sulfonate salt having the structure
wherein each occurrence of X is independently halogen or hydrogen provided that at
.least one X is halogen; m, p, and q are integers from 0 to 12; n is 0 :or 1 with the
proviso, that when n is 1, p and q are not both 0; R'-R3 are each independently Ci-Ci2
hydrocarbyl; R4 is Ci-Cu hydrocarbyl; and Y is selected from
(Figure Removed)
wherein R5 is hydrogen or Ci-Ci2 hydrocarbyl;
passing the coated substrate through a compression nip defined by a nip roll and a
casting drum having a microstructured pattern master; and
curing the curable composition while the curable composition is in contact with the
microstructured pattern master.
Methods of coating a curable composition on a surface of a substrate are described,
for example, in U.S. Patent Nos. 5,175,030 to Lu et al., 5,183,597 to Lu, 5,271,968 to
Coyle et al., 5,468,542 to Crouch, 5,626,800 to Williams et al., and 6,280,063 to Fong
et a!., as well as U.S. Patent Application Publication No. 2003/0108710 Al to Coyle
etal.
Methods of creating microstructured surfaces include, for example, U.S. Patent Nos.
5,175,030 to Lu et al., 5,183,597 to Lu, 5,468,542 to Crouch, 5,626,800 to Williams et
al., 5,917,664 to O'Neill et al., 5,919,551 to Cobb, Jr. et al., and 6,280,063 to Fong et
al, as well as U.S. Patent Application Publication No. 2003/0108710 Al to Coyle et
al.
One embodiment is a light management film including any of the above first layer
compositions and second layer compositions, and prepared by any of the above
methods.
Another'embodiment is a flat patent display comprising the light management layer.
The light management film is useful as a component of a flat panel display or a backlight
display, as well as in projection displays, traffic signals, and illuminated signs.
Displays incorporating light management films are described, for example, in U.S.
Patent Nos. 5,161,041 to Abileah et al. and 6,052,164 to Cobb, Jr. et al, and U.S.
Patent Application Publication No. 2003/0214728 Al to Olczak et al.
FIG. 1 is a schematic cross-sectional view of a segment of a light management film 1.
The light management film comprising a first layer 10 and a second layer 20, which is
pictured as microstructured.
FIG. 2 is a schematic cross-sectional view of a segment of a light management film 1
comprising a first layer 10, a second layer 20, pictured as microstructured, a first
masking layer 30, and a second masking layer 40. Each masking layer contacts the
remainder of the light management layer via an adhesive face.
All ranges disclosed herein are inclusive of the endpoints, and the endpoints are
combinable with each other.
The invention is further illustrated by the following non-limiting examples.
EXAMPLES 1-26, COMPARATIVE EXAMPLES 1 AND 2
These examples describe the preparation and resistivity. testing of uncoated
polycarbonate films containing varying amounts of fluorinated phosphonium sulfonate
salt. It further includes static decay testing of uncoated and coated' films.
Polycarbonate resins containing tetrabutyl phosphonium perfluorobutylsulfonate
("FC-1") in the amounts specified in Tables 1 and 2, below, were extruded at 270*0
into base films having a thickness of about 175 micrometers. The film was extruded
between a polished chrome calendering roll maintained at 127°C and a steel
calendering roll coated with 3/8 to 1/2 inch thick, 70 durometer silicone rubber cooled
"with at 43°C water circulating inside the roll.
Surface resistivity was measured at 23°C and 50% relative humidity using a Keithley
model 6517A.Electrometer and Keithley model 8009 resistivity test fixture. The
electrodes were stainless steel covered by conductive rubber having dimensions of
50.8 millimeters outer diameter for the center electrode and 85.7 millimeters outer
diameter for top electrode. Resistances used to calculate resistivities were measured
at 100 volts for 10 minutes. The sample size was 10 centimeters square. Samples
were preconditioned for 48 'hours at 23 °C and 50% relative humidity before
measurements were conducted, and reported results are the average of three samples
per resin composition.
Static decay measurements were conducted on both uncoated and coated films.
Coated films were prepared as follows. During extrusion, the bottom masking layer,
obtained as Tru-Cling from Tredegar, was applied to the polycarbonate base film
described above. The curable coating composition contained about 60% of a
brominated difunctional acrylate, about 40% phenylthioethyl acrylate, and a trace
amount of photoinitiator. The brominated difunctional acrylate was
tetrabromobisphendl A diglycidyl ether diacrylate, having the structure below,
obtained from UCB Chemicals. The coating composition was applied to the bottommasked
base film by gravure roll at a thickness of about 40 micrometers. Surface
structures were impressed in the coating using a molding tool according to procedures
.described in U.S. Patent Application Publication No. 2003/0108710 to Coyle et al.
The surface structures had random patterns, with unsymmetrical tips and grooves, and
nommiform size, shape, orientation, and distance between grooves. The coating was
cured with UV light while in contact with the tool. A top mask, obtained as Hitachi
7325, was applied. Before static decay measurements, all films were preconditioned
,ifor.24 hours at 23°C and 50% relative humidity. To measure static decay time on
coated samples, samples measuring 3 inches by 8 inches (7.62 centimeters by 20.32
centimeters) were cut from the films, both masking layers were quickly (within about
1 second) peeled off to expose the base film and coated layer, the sample was
mounted in a static meter fixture to provide for measurement of the static charge at the
center of the coated side, the initial static charge was measured, and the time required
for the static charge to decrease to half its initial value (the "static decay half-life")
was recorded. For uncoated films, masking was removed and -10 kilovolts (kV)
static was applied to film surface prior to testing. Time required for static to decrease
to -5 kV was recorded as the static decay half-life.
Surface resistivity and static decay results for uncoated films are presented in Table 1.
Static decay results for coated films are presented in Table 2. The results show that
surface resistivity and static decay half-life decrease roughly in proportion to the
amount of fluorinated phosphonium sulfonate salt incorporated into the base resin.
' Many of the films exhibited decay half-lives in the desirable range of about 1 to about
100 seconds/and surface resistivities in the desirable range of about 10" to about 1014
ohm/m2. It was surprising that the coated sides of the films exhibited desirable
antistatic characteristics even though the antistatic agent was incorporated only in the
base film (not the coated layer).
(Table Removed)
While the invention has been described with reference to a preferred embodiment, it
will be understood by those skilled in the art that various changes may be made and
equivalents may be substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications may be made to adapt a particular
situation or material to the teachings of the invention without departing from the
essential scope thereof. Therefore, it is intended that the invention not be limited to
the particular embodiment disclosed as the best mode contemplated for carrying out
this invention, but that the invention will include all, embodiments falling within the
scope of the appended claims.
The use of the terms "a" and "an" and "the" and similar referents in the context of
describing the invention (especially in the context of the following claims) are to be
construed to cover both the singular and the plural, unless otherwise indicated herein
or clearly contradicted by context. Further, it should further be noted that the terms
"first," "second," and the like herein do not denote any order, quantity, or importance,
but rather are used to distinguish one element from another.
All cited patents, patent applications, and other references are incorporated herein by
reference in their entirety.

CLAIMS:
1. A light management film, comprising:
a.first layer comprising
a thermoplastic resin selected from aromatic polycarbonates, polyetherimides,
.polyesters, polyphenylene ethers, polyphenylene ether/styrene polymer blends,
polyamides, polyketones, acrylonitrile-butadiene-styrenes, and blends thereof, and
a phosphonium sulfonate salt having the structure
(Figure Removed)
wherein each occurrence of X is independently halogen or hydrogen provided that at
least one X is halogen; m, p, and q are integers from 0 to 12; n is 0 or 1 with the
proviso that when n is 1, p and q are not both 0; R'-R3 are each independently Ci-Cia
hydrocarbyl; R4 is Ci-Cjg hydrocarbyl; and Y is selected from
(Figure Removed)
wherein.R5 is hydrogen or Ci-C|2 hydrocarbyl; and
a second layer disposed on a tace of the first layer; wherein the second layer is the
:ured product of a curable composition; and wherein the second layer has an index of
•efraction of at 1 east 1.5.
1. The light management film of claim 1, wherein the thermoplastic comprises an
iromatic polycarbonate.
!. The light management film of claim 1, wherein n, p, and q are zero, and m is 1
4. The light management film of claim 1, wherein the phosphonium sulfonate salt
comprises tetra-n-butylphosphonium nonafluoro-n-butylsulfonate.
5. The light management film of claim 1, wherein the phosphonium sulfonate salt
is present at about 0.00001 to about 2 weight percent, based on the total composition
of the first layer.
6. The light management film of claim 1, wherein, the light management film is
substantially free of fluorinated compounds other than fluorinated phosphonium
sulfonate salts.
7. The light management film of claim 1, wherein the first layer has a thickness
of about 25 to about 300 micrometers.
8. The light management film of claim 1, wherein the curable composition
comprises a polymerizable compound comprising at least one functional group
selected from (meth)acrylate, vinyl, and epoxide.
9. The light management film of claim 8, wherein the curable composition
further comprises metal oxide nanoparticles.
10. The light management film of claim 8, wherein the curable composition
further comprises a polymerization initiator. , .
11. The light management film of claim 1, wherein the curable composition
comprises a multifunctional (meth)acrylate having the structure
(Figure Removed)
wherein R6 is hydrogen or methyl; X1 is O, NH, or S; R7 is substituted or
unsubstituted Ci-Cioo hydrocarbyl having a valence of r; and r is 2, 3, or 4.
12. The light management film of claim 1, wherein the curable composition
comprises an alkane diol di(meth)acrylate having 2 to about 12 carbon atoms in the
alkane moiety.
13. The light management film of claim 1, wherein the curable composition
comprises
a difunctional (meth)acrylate having the structure
wherein R6 is hydrogen or methyl; X1 is 0, NH, or S; and R8 has the structure
wherein Q is -C(CH3)2-, -CH2-, -O-, -S-, -C(Q)~, -S(O)-, or -S(O)z-; R9 is C,-C6
alkylerie or hydroxy-silbstituted C|-Ce alkylene; each occurrence oft is independently
0,1,2,3, or 4; and d is 1 to 3;
an arylether (meth)acrylate having the structure
(Figure Removed)
wherein R6 is hydrogen or methyl; X1 is O, NH, or S; X2 is O, NH, or S; R10 is'
substituted or unsubstituted divalent C|-Ci2 aikylene or alkenylene; Ar is substituted
or unsubstituted Q-C^ aryl, including phenyl; wherein the substitution on the Rloand
Ar may independently include fluorine, chlorine, bromine, iodine, C\-C(, alkyl, Ci-Cs
perhalogenated alkyl, hydroxy, C|-C6 ketone, C\-Ct, ester, N,N-di(Cj-C3)alkylarnide,
or a combination comprising at least one of the foregoing substituents; and
a polymerization initiator.
14. The article of claim 13, wherein the difunctional (meth)acrylate is present in
an amount of about 1:0 to about 90 weight percent based on the total curable
composition.
15. The article of claim 13, wherein the arylether (meth)acrylate monomer is
present in an amount of about 35 to about 70 weight percent based on the .total curable
composition.
16. The article of claim 1, wherein the curable composition comprises
a difunctional (meth)acrylate having the structure
wherein R6 is hydrogen or methyl; X1 is O, NH, or S; and R* has the structure
wherein Q is -C(CH3)2- -CH2-, -O-, -S-, -C(OH -S(OK or -S(O)2-; R9 is C,-C6
alkylene or hydroxy-substituted Ci-Cs alkylene; each occurrence oft is independently
0,1,, 2,3, or 4; and d is 1 to 3;. ,
an arylether (meth)acrylate having the structure
. wherein R6 is hydrogen or methyl; X1 is O or S; X2 is O, NH, or S; R10 is substituted
or unsubstituted. divalent C|-C|2 alkylene or alkenylene; Ar is substituted or
unsubstituted Q-C|2 aryl, including phenyl; wherein the substitution on the R'°and
Ar may independently include fluorine, chlorine, bromine, iodine, Q-C6 alkyl, Ci-Ca
perhalogenated alkyl, hydroxy, Ci-Ca ketone, C\-C(, ester, N,N-di(C|-C3)alkylamide,
or a combination comprising at least one of the foregoing substituents;
a brominated aromatic (meth)acrylate having the structure
.wherein R6 is hydrogen or methyl; X1 is 0 or S; X3 is O or S; r is 0,1, 2, or 3, and s is
0 or 1, with the proviso that if r is 0 then s is 0; and u is 3,4, or 5; and
a polymerization initiator.
29
17. The Jight management film of claim 1, wherein the curable composition
comprises a high refractive index monomer haying the structure
(Figure Removed)
wherein Z is an ethylenically unsaturated group;
X4isO,S,orNH;
L1 and L2 are each independently Ci-Cj alkylene, -(Ci-Cs alkylene)-S-(Ci-C3
R11 is hydrogen or C|-C6 alkyl;
R12 and R13 are each independently aryl, including phenylor naphthyl, aryl(C]-C6
alkylene)-, heteroaryl, or heteroaryl(C|-Q alkylene)-, each of which group is
substituted with 0 to 5 substituents independently chosen from halogen, C|-C4 alkyl,
d-C4 alkoxy, (Ci-C4 alkyl)S-, CrC4 haloalkyl, and CrC4 haloalkoxy; and
Y1 and Y2 are each independently O, S, NH, or N.
1 8. The light management film of claim 1 7,
wherein Y1 and Y2 are both S, and
wherein
i) X4 >s S, or
ii) at least one of R12 and R13 is heteroaryl or heteroarylCQ-Q alkylene) substituted as
previously described, or
iii) one or both of L1 and L2 are -(C|-C3 alkyiene)-S-(C]-Ca alkylene)-, or -(C|-C3
alkylene)-O-(C]-C3alkylene)-. , .
19. The light management film of claim 17,
wherein Y1 or Y2 is N, and each corresponding combination R12-Y* or R1?-Y2 is
independently an N-containing heteroaryl excluding carbazole.
20. The light management film of claim 17, wherein Z is acryloy], methacryloyl,
.vinyl,-or ally!; X is O or S; and R is hydrogen.
21. The light management film of claim 1, wherein the second layer has a
refractive index of at least 1.61.
22.-, The light management film of claim 1, wherein the second layer has a
thickness of at about 10 to about 100 micrometers.
; 23.-' The light management layer of claim 1, further comprising a masking layer
disposed on a surface of the first layer opposite the second layer.
24. The light management layer of claim 1, further comprising a masking layer
disposed on a.surface of the second layer opposite the first layer.
25. A light management film, comprising:
a first layer comprising
an aromatic polycarbonate, and .
a phosphonium sulfonate salt having the structure
O R 1
CXjtCXj^-S-O- R'-P^-R2
wherein each occurrence of X is independently halogen or hydrogen provided that at
least one X is halogen; R'-R3 are each independently Ci-Ciz hydrocarbyl; and R4 is
Ci-Ci8 hydrocarbyl; and
a second layer disposed on a face of the first layer; wherein the second layer has an
index of refraction of at least 1.5; and wherein the second layer is the cured product of
a curable composition comprising a multifunctional (meth)acrylate having the
structure
wherein R6 is hydrogen or methyl; X1 is 0, NH, or S; R7 is substituted or
imsubstituted Ci-Cioo hydrocarbyl having a valence of r; and r is 2, 3, or 4.
26. A light management film, comprising:
a first layer comprising
an aromatic polycarbonate, and
tetra-n-butylphosphonium nonafluoro-n-butylsulfonate; and
a second layer disposed on a face of the first layer; wherein the second layer has an
index of refraction of at least 1.61; and wherein the second layer is the cured product
of a curable composition comprising
a di functional (meth)acrylate having the structure
wherein R6 is hydrogen or methyl; X1 is 0, NH, or S; and R8 has the structure
wherein Q is -C(CH3)2- -CH2-, -C(O)-, -O, -S- -S(O)-, or-S(O)2-; R9 is CrC6
alkylene or hydroxy-substituted Ci-Ce alkylene; each occurrence oft is independently
0, 1, 2, 3, or 4; and d is 1 to 3;
an arylether (meth)acrylate having the structure
(Figure Removed)
wherein R6 is hydrogen or methyl; X1 is O, NH, or S; X2 is O, NH, or S; R'° is
substituted or unsubstituted divalent C|-Ci2 alkylene or alkenylene; Ar is substituted
or unsubstituted Ce-Cij aryl, including phenyl; wherein the substitution on the R10 and
Ar may independently include fluorine, chlorine, bromine, iodine, C\-C(, alky], Ci-Cs
perhalogenated alkyl, hydroxy, Ci-Ce ketone, CI-C& ester, N,N-di(Ci-C3)alkylamide,
or a combination comprising at least one of the foregoing substituents; and
a polymerization initiator.
27. A method of preparing a light management film, comprising:
coating a curable composition on a surface of a substrate; wherein the substrate
comprises
a thermoplastic resin selected from aromatic polycarbonates, polyetherimides,
polyesters, polyphenylene ethers, polyphenylene ether/styrene polymer blends,
polyamides, polyketones, acrylonitrile-butadiene-styrenes, and blends thereof; and
a phosphonium sulfonate salt having the structure
wherein each occurrence of X is independently halogen or hydrogen provided that at
least one X is halogen; m, p, and q are integers from 0 to 12; n is 0 or 1 with the
proviso that when n is 1, p and q are not both 0; R'-R3 are each independently CpCu
hydrocarbyl; R4 is Ci-Ci? hydrocarby); and Y is selected from
(Figure Removed)
wherein R5 is hydrogen or Ci-Ci2 hydrocarbyl;
passing the coated substrate through a compression nip defined by a nip roll and a
casting drum having a microstructured pattern master; and
curing the curable composition while the curable composition is in contact with the
microstructured pattern master.
28. A light management film prepared by the method of claim 27.
29. A flat panel display comprising the light management layer of claim 1.
30. A light management film, comprising:
a first layer comprising
a thermoplastic resin selected from aromatic polycarbonates, polyetherimides,
polyesters, polyphenylene ethers, polyphenylene ether/styrene polymer blends,
polyamides, polykclones, acrylonitrile-butadiene-styrenes, and blends thereof, and
a phosphonium sulfonate salt having the structure
wherein, each occurrence of X is independently halogen or hydrogen provided that at
least one X is halogen; m, p, and q are integers from 0 to 12; n is 0 or 1 with the
proviso that when n is 1, p and q are not both 0; R'-R3 are each independently Ci-Qa
hy