US20080124555A1

US20080124555A1 - Polymerizable composition comprising perfluoropolyether urethane having ethylene oxide repeat units

Info

Publication number: US20080124555A1
Application number: US11/564,463
Authority: US
Inventors: Thomas P. Klun; Richard J. Pokorny; Joan M. Noyola
Original assignee: 3M Innovative Properties Co
Current assignee: 3M Innovative Properties Co
Priority date: 2006-11-29
Filing date: 2006-11-29
Publication date: 2008-05-29
Also published as: US8415014B2; US20100055470A1; WO2008067262A1; TW200837381A; EP2087053A4; EP2087053B1; US20130004773A1; KR101455421B1; US8383694B2; KR20090086613A; CN101541900B; US20120142856A1; JP2010511206A; JP5694667B2; TWI457587B; CN101541900A; EP2087053A1

Abstract

Presently described are optical substrates having a surface layer and optical displays comprising such optical substrates. The surface layer comprises the reaction product of a polymerizable mixture comprising at least one perfluoropolyether urethane polymeric material comprising at least two free-radically polymerizable groups and greater than 6 ethylene oxide repeat units and at least one non-fluorinated crosslinker comprising at least two free-radically polymerizable groups.

Description

BACKGROUND OF THE INVENTION

Hardcoats have been used to protect the face of optical displays. These hardcoats typically contain inorganic oxide particles, e.g., silica, of nanometer dimensions dispersed in a binder precursor resin matrix, and sometimes are referred to as “ceramers”.
U.S. Pat. No. 6,132,861 (Kang et al. '861); U.S. Pat. No. 6,238,798 B1 (Kang et al. '798); U.S. Pat. No. 6,245,833 B1 (Kang et al. '833); U.S. Pat. No. 6,299,799 (Craig et al.) and Published PCT Application No. WO 99/57185 (Huang et al.) describe ceramer compositions containing blends of colloidal inorganic oxide particles, a curable binder precursor and certain fluorochemical compounds. These compositions are described as providing stain and abrasion resistant hardcoats in a single layer coating.
U.S. Pat. No. 6,660,389 (Liu et al.) describes information display protectors for display devices having an information display area, comprising a stack of flexible substantially transparent sheets, the sheets having on one side thereof an adhesive layer and having on the other side thereof a hardcoat layer comprising inorganic oxide particles dispersed in a binder matrix and a low surface energy fluorinated compound, the stack being cut so that the sheets will fit the information display area. The low surface energy fluorinated compound can be part of the hardcoat layer or can be a separate layer atop the hardcoat layer. The protectors have very good scratch, smudge and glare resistance. The stack of protectors can be stored, for example, on a personal digital assistant or its cover or case.
WO 2005/111157 describes (Abstract) A hard coating composition for use as a stain repellent single layer on an optical display. The coating composition adds a monomer of a mono or multi(methyl)acrylate bearing at least one monovalent hexafluoropolypropylene oxide derivative and a free radically reactive compatibilizer consisting of either a fluoroalkyl-group containing acrylate compatibilizer or a fluoroalkylene-group containing acrylate compatibilizer to a conventional hydrocarbon-based hard coat formulation. The resultant coating is substantially smooth and forms a durable surface layer that has low surface energy that is stain and ink repellent.
WO2006/102383 describes various polymerizable perfluoropolyether urethane additives and there use as hardcoats for optical displays.
WO 03/002628 describes (Abstract) A perfluoropolyether-containing composition which has an affinity for nonfluorinated substrates and can form on the surface thereof a film firmly adherent to the surface. It is a composition containing carbon-carbon double bonds which comprises (A) a triisocyanate obtained by trimerizing a diisocyanate and (B) a combination of at least two compounds having active hydrogen, the component (B) comprising (B-1) a perfluoropolyether having at least one active hydrogen atom and (B-2) a monomer having an active hydrogen atom and a carbon-carbon double bond.

SUMMARY OF THE INVENTION

Presently described are optical substrates having a surface layer and optical displays comprising such optical substrates. The surface layer comprises the reaction product of a polymerizable mixture comprising at least one perfluoropolyether urethane polymeric material comprising at least two free-radically polymerizable groups and greater than 6 ethylene oxide repeat units and at least one non-fluorinated crosslinker comprising at least two free-radically polymerizable groups.
In another embodiment, a free-radically polymerizable composition is described comprising a mixture of reaction products of i) at least one polyisocyanate; ii) at least one isocyanate reactive perfluoropolyether compound; iii) at least one isocyanate reactive compound comprising greater than 6 repeat units of ethylene oxide; and iv) at least one isocyanate reactive non-fluorinated crosslinker comprising at least two free-radically polymerizable groups. The composition may be a coating dispersed in an alcohol-containing solvent that is particularly useful for coating optical substrates such as polycarbonate, acrylic, cellulose acetate, and cellulose triacetate.
Also described are certain multifunctional perfluoropolyether urethane compositions that comprise the reaction product of a polyisocyanate with an isocyanate reactive perfluoropolyether compound, an isocyanate reactive multifunctional hydrocarbon crosslinker, and an isocyanate reactive compound having greater than 6 ethylene oxide repeat units. Preferred multifunctional perfluoropolyether urethane compositions are set forth in the claims.
In each of these embodiments, the perfluoropolyether urethane polymeric material comprises at least two (meth)acrylate groups such as a terminal group having at least two (meth)acrylate groups. The perfluoropolyether urethane may comprise a monovalent perfluoropolyether moiety such as F(CF(CF₃)CF₂O)_aCF(CF₃)— wherein a ranges from 4 to 15. At least one (e.g. non-fluorinated) hydrocarbon crosslinker that comprises at least three free-radically polymerizable groups is typically employed. In some aspects, the surface layer or polymerizable composition further comprises inorganic oxide particles. In other aspects, a hardcoat layer comprising inorganic oxide particles is disposed between the substrate and an inorganic particle free surface layer.

DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS

Presently described are optical displays including a light transmissive optical substrate. The surface layer of the optical substrate comprises the reaction product of a polymerizable mixture comprising at least one free-radically polymerizable perfluoropolyether urethane polymeric material having ethylene oxide repeat units. In another embodiment, certain multifunctional perfluoropolyether urethane compositions are described. In another embodiment, coating compositions are described that comprise a (e.g. ultraviolet) polymerizable mixture comprising the perfluoropolyether urethane polymeric material dispersed in an alcohol-containing solvent.
In one aspect a free-radically polymerizable coating composition is described that comprises a mixture of reaction products of
i) at least one polyisocyanate,
ii) at least one isocyanate reactive perfluoropolyether compound,
iii) at least one isocyanate reactive compound containing greater than 6 ethylene oxide repeat units, and
iv) at least one isocyanate reactive (e.g. non-fluorinated) hydrocarbon crosslinker comprising two or more free-radically polymerizable groups.
The perfluoropolyether compound (i.e. ii) and ethylene oxide repeat unit containing compound (i.e. iii) preferably comprise a (e.g. terminal) alcohol, thiol, or amine group. Typically both the perfluoropolyether compound and the ethylene oxide compound contain (e.g. terminal) reactive alcohol groups.
For embodiments wherein the perfluoropolyether compound, ethylene oxide repeat unit containing compound, and hydrocarbon crosslinker have monofunctional isocyanate reactivity the isocyanate employed is typically at least trifunctional. However, when one of more of the isocyanate reactive compounds have at least difunctional isocyanate reactivity, difunctional isocyanates can be employed.
The hydrocarbon crosslinker (i.e. iv) typically comprises (meth)acryl groups such as (meth)acrylate groups. A substantial excess of hydrocarbon crosslinker (i.e. iv) is typically employed such that the perfluoropolyether urethane polymeric material as well as other reaction products of the reaction mixture comprise unreacted free-radically polymerizable groups which can be subsequently cured for example by radiation (e.g. UV) curing.
Typically, the perfluoropolyether urethane composition is made by first reacting a polyisocyanate with a perfluoropolyether compound containing an alcohol, thiol, or amine group, followed by reaction with one or more ethylene oxide compounds containing an alcohol, thiol, or amine group. The perfluoropolyether urethane additive is then combined with the (e.g. non-fluorinated) isocyanate reactive multifunctional free-radically polymerizable (e.g. (meth)acrylate) crosslinker. Alternatively, these perfluoropolyether urethane additives can be formed by other reaction sequences such as by first reacting the polyisocyanate with the crosslinker, followed by the addition of the ethylene oxide containing compound. In addition, the additives could be made by reacting all three components concurrently.
Although these reaction sequences are generally conducted in a solvent that does not contain hydroxyl groups (such as MEK) in the presence of a catalyst such as an organotin compound, the composition thus formed has improved compatibility with hydroxyl group containing solvents, commonly know as alcohols. Alcohol based coating compositions are especially useful for coating light transmissive substrates such as polycarbonate, acrylic, cellulose acetate, and cellulose triacetate which are susceptible to swelling, cracking, or crazing by organic solvents such as ketones (e.g. MEK), aromatic solvents (e.g. toluene), and esters (e.g. acetate solvents).
One or more polyisocyanate materials are employed in the preparation of the perfluoropolyether urethane. A variety of polyisocyanates may be utilized as component i) in the preparation of the perfluoropolyether urethane polymeric material.
“Polyisocyanate” means any organic compound that has two or more reactive isocyanate (—NCO) groups in a single molecule such as diisocyanates, triisocyanates, tetraisocyanates, etc., and mixtures thereof. Cyclic and/or linear polyisocyanate molecules may usefully be employed. For improved weathering and diminished yellowing the polyisocyanate(s) of the isocyanate component is typically aliphatic.
Useful aliphatic polyisocyanates include, for example, bis(4-isocyanatocyclohexyl)methane (H₁₂MDI) such as available from Bayer Corp., Pittsburgh, Pa. under the trade designation “Desmodur W”; isophorone diisocyanate (IPDI) such as commercially available from Huels America, Piscataway, N.J.; hexamethylene diisocyanate (HDI) such as commercially available from Aldrich Chemical Co., Milwaukee, Wis.; trimethyl hexamethylene diisocyanate such as commercially available from Degussa, Corp., Dusseldorf, Germany under the trade designation “Vestanate TMDI”; and m-tetramethylxylene diisocyanate (TMXDI) such as commercially available from Aldrich Chemical Co., Milwaukee, Wis. Although typically less preferred, aromatic isocyanates such as diphenylmethane diisocyanate (MDI) such as commercially available from Bayer Corp., Pittsburgh, Pa. under the trade designation “Mondur M”; toluene 2,4-diisocyanate (TDI) such as commercially available from Aldrich Chemical Co., Milwaukee, Wis., and 1,4-phenylene diisocyanate are also useful.
Preferred polyisocyanates include derivatives of the above-listed monomeric polyisocyanates. These derivatives include, but are not limited to, polyisocyanates containing biuret groups, such as the biuret adduct of hexamethylene diisocyanate (HDI) available from Bayer Corp. under the trade designation “Desmodur N-100”, polyisocyanates based on HDI containing isocyanurate groups, such as that available from Bayer Corp. under trade designation “Desmodur N-3300”, as well as polyisocyanates containing urethane groups, uretdione groups, carbodiimide groups, allophonate groups, and the like. These derivatives are preferred as they are polymeric, exhibit very low vapor pressures and are substantially free of isocyanate monomer.
Other polyisocyanates that may be used are available from Bayer Polymers LLC of Pittsburgh, Pa. under the trade designations “Desmodur TPLS2294”, and “Desmodur N 3600”
Various isocyanate reactive perfluoropolyethers materials can be utilized as component ii). The synthesis of various perfluoropolyether materials having (e.g. terminal) isocyanate reactive groups such as OH, SH or NHR wherein R is H of an alkyl group of 1 to 4 carbon atoms is known. For example, a methyl ester material (e.g. having an average molecular weight of 1,211 g/mol) for preparation of the alcohol can be prepared according to the method reported in U.S. Pat. No. 3,250,808 (Moore et al.), the disclosure of which is incorporated herein by reference, with purification by fractional distillation. Perfluoropolyether alcohol materials can be made by a procedure similar to that described in U.S. Publication No. 2004-0077775, filed May 24, 2002. Perfluoropolyether alcohol materials having an SH group can be made using this same process by use of aminoethane thiol rather than aminoethanol. Perfluoropolyether amine materials can be synthesized as described in US 2005/0250921.
One or more isocyanate reactive perfluoropolyether materials are employed in the preparation of the perfluoropolyether urethane. The perfluoropolyether urethane material is preferably prepared from an isocyanate reactive HFPO-material. Unless otherwise noted, “HFPO-” refers to the end group F(CF(CF₃)CF₂O)_aCF(CF₃)— of the methyl ester F(CF(CF₃)CF₂O)_aCF(CF₃)C(O)OCH₃, wherein “a” averages 2 to 15. In some embodiments, a averages between 3 and 10 or a averages between 5 and 8. Such species generally exist as a distribution or mixture of oligomers with a range of values for a, so that the average value of a may be non-integer. For example, in one embodiment, “a” averages 6.2. The molecular weight of the HFPO-perfluoropolyether material varies depending on the number (“a”) of repeat units from about 940 g/mole to about 1600 g/mole, with 1100 g/mole to 1400 g/mole typically being preferred.
One or more isocyanate reactive ethylene oxide repeat unit materials are employed in the preparation of the perfluoropolyether urethane. The ethylene oxide containing isocyanate reactive compound generally comprises greater than 6 repeat units of ethylene oxide. The number of ethylene oxide repeat units may be at least 7, 8, or 9 repeat units. In some embodiments, the isocyanate reactive ethylene oxide containing compound has at least 10 repeat units of ethylene oxide. For example, the number of repeat units may be 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20. Generally the number of ethylene oxide repeat units does not exceed about 40 and may be for example up to 25, 30, or 35 repeat units.
The ethylene oxide containing compounds may be represented by the following formula:
X¹(C₂H₄O)_jR^j
wherein

X¹is OH, SH or NHR, where R is H or lower alkyl of 1 to 4 carbon atoms; and

R₁is H, —C(O)C(R₂)═CH₂, where R₂is a lower alkyl of 1 to 4 carbon atoms or H or F, or a group selected from alkyl, aryl, alkaryl, aralkyl, that can optionally be substituted with a heteroatom, a heteoratom functional groups (such as —OH —SH, and —NH₂), or a (meth)acryl functional group; and
j ranges from 7 to 40.
The ethylene oxide containing compound may also comprise other alkylene oxide compounds such as propylene oxide. In such embodiment, a major amount of the alkylene oxide repeat units are typically ethylene oxide repeat units.
Various isocyanate reactive non-fluorinated hydrocarbon crosslinkers can be employed in the synthesis of the perfluoropolyether urethane polymeric material. Such crosslinkers comprise at least two and preferably three free-radically polymerizable groups. The free-radically polymerizable groups are preferably (meth)acryl and more preferably (meth)acrylate groups.
Suitable isocyanate reactive non-fluorinated hydrocarbon crosslinkers may be described by the formula:
HOQ(A)_p;
wherein

Q is a connecting group of valency at least 2;

A is a (meth)acryl functional group such as —XC(O)C(R2)=CH2, where

- X is O, S or NR, where R is H or lower alkyl of 1 to 4 carbon atoms, and
- R₂is a lower alkyl of 1 to 4 carbon atoms or H or F; and
  p ranges from 2 to 6.

Q can comprise a straight chain, branched chain, or cyclic-containing connecting group. Q can include an alkylene, an arylene, an aralkylene, an alkarylene. Q can optionally include heteroatoms such as O, N, and S, and combinations thereof. Q can also optionally include a heteroatom-containing functional group such as carbonyl or sulfonyl, and combinations thereof.
Exemplary isocyanate reactive crosslinkers include for example 1,3-glycerol dimethacrylate available from Echo Resin Inc. of Versailles, Mo. and pentaerythritol triacrylate, available from Sartomer of Exton, Pa. under the trade designation “SR444C”. Additional useful isocyanate reactive (meth)acrylate crosslinkers include hydantoin moiety-containing poly(meth)acrylates, for example, as described in U.S. Pat. No. 4,262,072 (Wendling et al.).
If the mole fraction of isocyanate groups is arbitrarily given a value of 1.0, then the total mole fraction of isocyanate reactive groups used in making the perfluoropolyether urethane material is 1.0 or greater. Although, the polymerizable compositions described herein typically comprise at least 0.2 mole fraction of crosslinking agent(s), it is typically preferred to maximize the concentration of isocyanate reactive hydrocarbon crosslinker to improve the durability and compatibility with the binder of the hardcoat. Accordingly, the total amount of crosslinking agent(s) may comprise at least 0.5 mole fraction and may be at least 0.6 mole fraction, at least 0.7 mole fraction, at least 0.8 mole fraction, or at least 0.9 mole of the sum of the isocyanate reactants. The mole fraction of the perfluoropolyether reactant is typically at least 0.05 and no greater than 0.5. The mole fraction of ethylene oxide repeat unit containing reactant is also typically at least 0.05 and no greater than 0.5.
The reaction product generally includes a distribution of various reaction products. In addition to the reaction product of the polyisocyanate with all three reactants (ii, iii, and iv) the reaction product of the polyisocyanate with two of the three as well as reaction products of the polyisocyanate the individual reactants are also present.
For example, one representative structure formed by the reaction product of a biuret of HDI with one equivalent of HFPO oligomer amidol HFPO—C(O)NHCH₂CH₂OH wherein “a” averages 2 to 15, and further with two equivalents of pentaerythritol triacrylate is shown as follows
In one preferred embodiment, the perfluoropolyether urethane composition is of the formula:
Ri-(NHC(O)XQRf), —(NHC(O)OQ(A)p), —(NHC(O)X^j(C₂H₄O)_jR^j,
wherein Ri is a residue of a multi-isocyanate;

X and X^jare each independently O, S or NR, where R is H or lower alkyl of 1 to 4 carbon atoms;

Q is independently a connecting group of valency at least 2;

Rf is a monovalent perfluoropolyether moiety composed of groups comprising the formula A is a (meth)acryl functional group such as —XC(O)C(R2)=CH2, where R2 is a lower alkyl of 1 to 4 carbon atoms or H or F;

p is 2 to 6;
j ranges from 7 to 40; and
R^jis H, —C(O)C(R₂)═CH₂, where R₂is a lower alkyl of 1 to 4 carbon atoms or H or F, or a group selected from alkyl, aryl, alkaryl, aralkyl, that can optionally be substituted with a heteroatom, heteoratom functional groups (such as —OH —SH, and —NH₂), or a (meth)acryl functional group.
Depending on the number of individual materials employed as well as the functionality of the reactants, a variety of perlfluoropolyether urethane materials can be prepared having at least one of each of the unit of this formula.
Q in association with the Rf group is a straight chain, branched chain, or cycle-containing connecting group. Q can include an alkylene, an arylene, an aralkylene, an alkarylene. Q can optionally include heteroatoms such as O, N, and S, and combinations thereof. Q can also optionally include a heteroatom-containing functional group such as carbonyl or sulfonyl, and combinations thereof.
When X is O, Q is typically not methylene and thus contains two or more carbon atoms. In some embodiments, X is S or NR. In some embodiments, Q is an alkylene having at least two carbon atoms. In other embodiments, Q is a straight chain, branched chain, or cycle-containing connecting group selected from arylene, aralkylene, and alkarylene. In yet other embodiments, Q contains a heteroatom such as O, N, and S and/or a heteroatom containing functional groups such as carbonyl and sulfonyl. In other embodiments, Q is a branched or cycle-containing alkylene group that optionally contains heteroatoms selected from O, N, S and/or a heteroatom-containing functional group such as carbonyl and sulfonyl. In some embodiments Q contains a nitrogen containing group such an amide group such as —C(O)NHCH₂CH₂—, —C(O)NH(CH₂)₆—, and —C(O)NH(CH₂CH₂O)₂CH₂CH₂—.
Various other reactants can be included in the preparation of the perfluoropolyether urethane such as described in WO2006/102383; incorporated herein by reference.
The perfluoropolyether urethane polymeric material described herein may be employed alone or in combination with various other fluorinated compounds having at least one moiety selected from fluoropolyether, fluoroalkyl, and fluoroalkylene linked to at least one free-radically reactive group. When a second fluorinated compound is employed, it is typically preferred that such second fluorinated compound also comprises an HFPO-moiety. Various fluorinated materials that can be employed in combination with the perfluoropolyether urethane polymeric material described are also described in WO2006/102383.
The polymerizable perfluoropolyether urethane composition is typically dispersed in a hardcoat composition in combination with a (e.g. alcohol based) solvent, applied to an optical substrate and photocured to form the easy to clean, stain and ink repellent light transmissible surface layer. The hardcoat is a tough, abrasion resistant layer that protects the optical substrate and the underlying display screen from damage from causes such as scratches, abrasion and solvents. Typically the hardcoat is formed by coating a curable liquid ceramer composition onto the substrate and curing the composition in situ to form a hardened film.
The surface energy can be characterized by various methods such as contact angle and ink repellency, as determined by the test methods described in the Examples. In this application, “stain repellent” refers to a surface treatment exhibiting a static contact angle with water of at least 70 degrees. More preferably, the contact angle is at least 80 degrees and most preferably at least 90 degrees. Alternatively, or in addition thereto, the advancing contact angle with hexadecane is at least 50 degrees and more preferably at least 60 degrees. Low surface energy results in anti-soiling and stain repellent properties as well as rendering the exposed surface easy to clean.
Another indicator of low surface energy relates to the extent to which ink from a pen or marker beads up when applied to the exposed surface. The surface layer and articles exhibit “ink repellency” when ink from pens and markers beads up into discrete droplets and can be easily removed by wiping the exposed surface with tissues or paper towels, such as tissues available from the Kimberly Clark Corporation, Roswell, Ga. under the trade designation “SURPASS FACIAL TISSUE.” Durability can be defined in terms of results from a modified oscillating sand test (Method ASTM F 735-94) carried out at 250 rpm for 5 minutes as described in the Test Methods of this application. Preferably, a durable coating exhibits an ink repellency loss value of 65 mm (75% loss) or less, more preferably 40 mm (45% loss) or less, most preferably 0 mm (no loss) of ink repellency (IR) in this test.
The perfluoropolyether urethane polymeric material described herein can be employed as the sole fluorinated component of a one-layer hardcoat composition. For embodiments wherein high durability is desired, the hardcoat composition typically further comprises (e.g. surface modified) inorganic particles. The thickness of the hardcoat surface layer is typically at least 0.5 microns, preferably at least 1 micron, and more preferably at least 2 microns. The thickness of the hardcoat layer is generally no greater than 25 microns. Preferably the thickness ranges from 3 microns to 5 microns.
Alternatively, an inorganic particle free perfluoropolyether urethane polymer containing surface layer may be employed alone for uses where durability is not required. In yet other embodiments, an inorganic particle free perfluoropolyether urethane polymer containing surface layer may be provided in combination with an inorganic particle containing hardcoat layer disposed between the substrate and the surface layer. This will be referred to as a two-layer hardcoat. In these embodiments, the surface layer preferably has a thickness ranging from about 10 to 200 nanometers.
For one-layer hardcoat embodiments, the total of all (per)fluorinated compounds, (e.g. the perfluoropolyether urethane(s) alone or in combination with other fluorinated compounds) ranges from 0.01% to 10%, and more preferably from 0.1% to 1%, of the total solids of the hardcoat composition. For two-layer hardcoat embodiments the amount of perfluoropolyether urethane(s) in the coating compositions ranges from 0.01 to 50 wt-% solids, and more preferably from 1 to 25 wt-% solids.
A variety of binder precursors that form a crosslinked polymeric matrix upon curing can be employed in the hardcoat. The isocyanate reactive non-fluorinated crosslinking materials previously described are suitable binder precursors.
Di(meth)acryl binder precursors include for example 1,3-butylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol monoacrylate monomethacrylate, ethylene glycol diacrylate, alkoxylated aliphatic diacrylate, alkoxylated cyclohexane dimethanol diacrylate, alkoxylated hexanediol diacrylate, alkoxylated neopentyl glycol diacrylate, caprolactone modified neopentylglycol hydroxypivalate diacrylate, caprolactone modified neopentylglycol hydroxypivalate diacrylate, cyclohexanedimethanol diacrylate, diethylene glycol diacrylate, dipropylene glycol diacrylate, ethoxylated bisphenol A diacrylate, hydroxypivalaldehyde modified trimethylolpropane diacrylate, neopentyl glycol diacrylate, polyethylene glycol diacrylate, propoxylated neopentyl glycol diacrylate, tetraethylene glycol diacrylate, tricyclodecanedimethanol diacrylate, triethylene glycol diacrylate, tripropylene glycol diacrylate.
Tri(meth)acryl binder precursore include for example glycerol triacrylate, trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylates (e.g. having 3 to 20 ethoxylate repeat), propoxylated glyceral triacrylates, trimethylolpropane triacrylate, tris(2-hydroxyethyl)isocyanurate triacrylate. Higher functionality (meth)acryl containing compounds include for example ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, ethoxylated pentaerythritol tetraacrylate, caprolactone modified dipentaerythritol hexaacrylate.
One commercially available form of pentaerythritol triacrylate (“PET3A”) is SR444C and one commercially available form of pentaerythritol tetraacrylate (“PET4A”) is SR295, each available from Sartomer Company of Exton, Pa.
Oligomeric (meth)acryl such as urethane acrylates, polyester acrylates, epoxy acrylates; and polyacrylamide analogues of the foregoing can also be employed as the binder.
In one embodiment, the binder may comprise one or more N,N-disubstituted acrylamide and or N-substituted-N-vinyl-amide monomers as described in Bilkadi et al. The hardcoat may be derived from a ceramer composition containing about 20 to about 80% ethylenically unsaturated monomers and about 5 to about 40% N,N-disubstituted acrylamide monomer or N-substituted-N-vinyl-amide monomer, based on the total weight of the solids in the ceramer composition.
To facilitate curing, polymerizable compositions described herein may further comprise at least one free-radical thermal initiator and/or photoinitiator. Typically, if such an initiator and/or photoinitiator are present, it comprises less than about 10 percent by weight, more typically less than about 5 percent of the polymerizable composition, based on the total weight of the polymerizable composition. Free-radical curing techniques are well known in the art and include, for example, thermal curing methods as well as radiation curing methods such as electron beam or ultraviolet radiation. Further details concerning free radical thermal and photopolymerization techniques may be found in, for example, U.S. Pat. No. 4,654,233 (Grant et al.); U.S. Pat. No. 4,855,184 (Klun et al.); and U.S. Pat. No. 6,224,949 (Wright et al.).
Useful free-radical thermal initiators include, for example, azo, peroxide, persulfate, and redox initiators, and combinations thereof.
Useful free-radical photoinitiators include, for example, those known as useful in the UV cure of acrylate polymers such as described in WO2006/102383.
The polymerizable composition for use as the surface layer or an underlying hardcoat layer preferably contains surface modified inorganic particles that add mechanical strength and durability to the resultant coating.
A variety of inorganic oxide particles can be used in the hardcoat. The inorganic oxide particles can consist essentially of or consist of a single oxide such as silica, or can comprise a combination of oxides, such as silica and aluminum oxide, or a core of an oxide of one type (or a core of a material other than a metal oxide) on which is deposited an oxide of another type. Silica is a common inorganic particle. The inorganic oxide particles are often provided in the form of a sol containing a colloidal dispersion of inorganic oxide particles in liquid media. The sol can be prepared using a variety of techniques and in a variety of forms including hydrosols (where water serves as the liquid medium), organosols (where organic liquids so serve), and mixed sols (where the liquid medium contains both water and an organic liquid), e.g., as described in U.S. Pat. No. 5,648,407 (Goetz et al.); U.S. Pat. No. 5,677,050 (Bilkadi et al.) and U.S. Pat. No. 6,299,799 (Craig et al.), the disclosure of which is incorporated by reference herein. Aqueous sols (e.g. of amorphous silica) can be employed. Sols generally contain at least 2 wt-%, at least 10 wt-%, at least 15 wt-%, at least 25 wt-%, and often at least 35 wt-% colloidal inorganic oxide particles based on the total weight of the sol. The amount of colloidal inorganic oxide particle is typically no more than 50 wt-% (e.g. 45 wt-%). The surface of the inorganic particles can be “acrylate functionalized” as described in Bilkadi et al. The sols can also be matched to the pH of the binder, and can contain counter ions or water-soluble compounds (e.g., sodium aluminate), all as described in Kang et al. '798.
Various high refractive index inorganic oxide particles can be employed such as for example zirconia (“ZrO₂”), titania (“TiO₂”), antimony oxides, alumina, tin oxides, alone or in combination. Mixed metal oxide may also be employed. Zirconias for use in the high refractive index layer are available from Nalco Chemical Co. under the trade designation “Nalco OOSSOO8” and from Buhler AG Uzwil, Switzerland under the trade designation “Buhler zirconia Z-WO sol”. Zirconia nanoparticle can also be prepared such as described in U.S. patent application Ser. No. 11/027,426 filed Dec. 30, 2004 and U.S. Pat. No. 6,376,590.
The inorganic nanoparticles are preferably treated with a surface treatment agent. Surface-treating the nano-sized particles can provide a stable dispersion in the polymeric resin. Preferably, the surface-treatment stabilizes the nanoparticles so that the particles will be well dispersed in the polymerizable resin and results in a substantially homogeneous composition. Furthermore, the nanoparticles can be modified over at least a portion of its surface with a surface treatment agent so that the stabilized particle can copolymerize or react with the polymerizable resin during curing. The incorporation of surface modified inorganic particles is amenable to covalent bonding of the particles to the free-radically polymerizable organic components, thereby providing a tougher and more homogeneous polymer/particle network.
In general, a surface treatment agent has a first end that will attach to the particle surface (covalently, ionically or through strong physisorption) and a second end that imparts compatibility of the particle with the resin and/or reacts with resin during curing. Examples of surface treatment agents include alcohols, amines, carboxylic acids, sulfonic acids, phosphonic acids, silanes and titanates. The preferred type of treatment agent is determined, in part, by the chemical nature of the metal oxide surface. Silanes are preferred for silica and other for siliceous fillers. Silanes and carboxylic acids are preferred for metal oxides such as zirconia. The surface modification can be done either subsequent to mixing with the monomers or after mixing. It is preferred in the case of silanes to react the silanes with the particle or nanoparticle surface before incorporation into the resin. The required amount of surface modifier is dependant upon several factors such as particle size, particle type, modifier molecular wt, and modifier type. In general, it is preferred that approximately a monolayer of modifier is attached to the surface of the particle. The attachment procedure or reaction conditions required also depend on the surface modifier used. For silanes it is preferred to surface treat at elevated temperatures under acidic or basic conditions for from 1-24 hr approximately. Surface treatment agents such as carboxylic acids may not require elevated temperatures or extended time.
Representative embodiments of surface treatment agents suitable for the compositions include compounds such as, for example, isooctyl trimethoxy-silane, N-(3-triethoxysilylpropyl)methoxyethoxyethoxyethyl carbamate, N-(3-triethoxysilylpropyl)methoxyethoxyethoxyethyl carbamate, 3-(methacryloyloxy)propyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-(methacryloyloxy)propyltriethoxysilane, 3-(methacryloyloxy)propylmethyldimethoxysilane, 3-(acryloyloxypropyl)methyldimethoxysilane, 3-(methacryloyloxy)propyldimethylethoxysilane, 3-(methacryloyloxy)propyldimethylethoxysilane, vinyldimethylethoxysilane, phenyltrimethoxysilane, n-octyltrimethoxysilane, dodecyltrimethoxysilane, octadecyltrimethoxysilane, propyltrimethoxysilane, hexyltrimethoxysilane, vinylmethyldiacetoxysilane, vinylmethyldiethoxysilane, vinyltriacetoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyltrimethoxysilane, vinyltriphenoxysilane, vinyltri-t-butoxysilane, vinyltris-isobutoxysilane, vinyltriisopropenoxysilane, vinyltris(2-methoxyethoxy)silane, styrylethyltrimethoxysilane, mercaptopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, acrylic acid, methacrylic acid, oleic acid, stearic acid, dodecanoic acid, 2-[2-(2-methoxyethoxy)ethoxy]acetic acid (MEEAA), beta-carboxyethylacrylate (BCEA), 2-(2-methoxyethoxy)acetic acid, methoxyphenyl acetic acid, and mixtures thereof.
The surface modification of the particles in the colloidal dispersion can be accomplished in a variety known ways, such as described in U.S. patent application Ser. No. 11/027,426 filed Dec. 30, 2004; U.S. Pat. No. 6,376,590.
A combination of surface modifying agents can be useful, wherein at least one of the agents has a functional group co-polymerizable with a hardenable resin. Combinations of surface modifying agent can result in lower viscosity. For example, the polymerizing group can be ethylenically unsaturated or a cyclic function subject to ring opening polymerization. An ethylenically unsaturated polymerizing group can be, for example, an acrylate or methacrylate, or vinyl group. A cyclic functional group subject to ring opening polymerization generally contains a heteroatom such as oxygen, sulfur or nitrogen, and preferably a 3-membered ring containing oxygen such as an epoxide.
A preferred combination of surface modifying agent includes at least one surface modifying agent having a functional group that is copolymerizable with the organic component of the polymerizable resin and a second amphiphilic modifying agent, such as a polyether silane, that may act as a dispersant. The second modifying agent is preferably a polyalkyleneoxide containing modifying agent that is optionally co-polymerizable with the organic component of the polymerizable composition.
Surface modified colloidal nanoparticles can be substantially fully condensed. Non-silica containing fully condensed nanoparticles typically have a degree of crystallinity (measured as isolated metal oxide particles) greater than 55%, preferably greater than 60%, and more preferably greater than 70%. For example, the degree of crystallinity can range up to about 86% or greater. The degree of crystallinity can be determined by X-ray diffraction techniques. Condensed crystalline (e.g. zirconia) nanoparticles have a high refractive index whereas amorphous nanoparticles typically have a lower refractive index.
The inorganic particles preferably have a substantially monodisperse size distribution or a polymodal distribution obtained by blending two or more substantially monodisperse distributions. Alternatively, the inorganic particles can be introduced having a range of particle sizes obtained by grinding the particles to a desired size range. The inorganic oxide particles are typically non-aggregated (substantially discrete), as aggregation can result in optical scattering (haze) or precipitation of the inorganic oxide particles or gelation. The inorganic oxide particles are typically colloidal in size, having an average particle diameter of 5 nanometers to 100 nanometers. The particle size of the high index inorganic particles is preferably less than about 50 nm in order to provide sufficiently transparent high-refractive index coatings. The average particle size of the inorganic oxide particles can be measured using transmission electron microscopy to count the number of inorganic oxide particles of a given diameter.
The optical film having a perfluoropolyether urethane containing surface layer as described herein may have a gloss or matte surface. Matte films typically have lower transmission and higher haze values than typical gloss films. For examples the haze is generally at least 5%, 6%, 7%, 8%, 9%, or 10% as measured according to ASTM D1003. Whereas gloss surfaces typically have a gloss of at least 130 as measured according to ASTM D 2457-03 at 60°; matte surfaces have a gloss of less than 120.
A particulate matting agent can be incorporated into the polymerizable composition in order to impart anti-glare properties to the surface layer. The particulate matting agent also prevents the reflectance decrease and uneven coloration caused by interference with an associated hard coat layer.
Exemplary systems incorporating matting agents into a hard coating layer, but having a different hard coating composition, are described, for example, in U.S. Pat. No. 6,693,746, and herein incorporated by reference. Further, exemplary matte films are commercially available from U.S.A. Kimoto Tech of Cedartown, Ga., under the trade designation “N4D2A.”
The amount of particulate matting agent added is between about 0.5 and 10% of the total solids of the composition, depending upon the thickness of the layer, with a preferred amount around 2%.
The average particle diameter of the particulate matting agent has a predefined minimum and maximum that is partially dependent upon the thickness of the layer. However, generally speaking, average particle diameters below 1.0 microns do not provide the degree of anti-glare sufficient to warrant inclusion, while average particle diameters exceeding 10.0 microns deteriorate the sharpness of the transmission image. The average particle size is thus preferably between about 1.0 and 10.0 microns, and more preferably between 1.7 and 3.5 microns, in terms of the number-averaged value measured by the Coulter method.
As the particulate matting agent, inorganic particles or resin particles are used including, for example, amorphous silica particles, TiO₂particles, Al₂O₃particles, cross-linked acrylic polymer particles such as those made of cross-linked poly(methyl methacrylate), cross-linked polystyrene particles, melamine resin particles, benzoguanamine resin particles, and cross-linked polysiloxane particles. By taking into account the dispersion stability and sedimentation stability of the particles in the coating mixture for the anti-glare layer and/or the hard coat layer during the manufacturing process, resin particles are more preferred, and in particular cross-linked polystyrene particles are preferably used since resin particles have a high affinity for the binder material and a small specific gravity.
As for the shape of the particulate matting agent, spherical and amorphous particles can be used. However, to obtain a consistent anti-glare property, spherical particles are desirable. Two or more kinds of particulate materials may also be used in combination.
One commercially available silica particulate matting agent having an average particle size of 3.5 microns is commercially available from W.R. Grace and Co., Columbia, Md. under the trade designation “Syloid C803”.
Other types of inorganic particles can also be incorporated into the hardcoat compositions. Particularly preferred are conducting metal oxide nanoparticles such as antimony tin oxide, fluorinated tin oxide, vanadium oxide, zinc oxide, antimony zinc oxide, and indium tin oxide. They can also be surface treated with materials such as 3-methacryloxypropyltrimethoxysilane. These particles can provide constructions with antistatic properties. This is desirable to prevent static charging and resulting contamination by adhesion of dust and other unwanted debris during handling and cleaning of the film. Preferably, such metal oxide particles are incorporated into the top (thin) layer of the two-layer constructions of this invention, in which the fluorinated hardcoat is applied to a hydrocarbon-based hardcoat. Examples of conducting metal oxide nanoparticles useful in this embodiment include antimony double oxide available from Nissan Chemical under the trade designations Celnax CXZ-2101P and CXZ-2101P-F2.
The perfluoropolyether urethane polymeric material alone or in combination with the hardcoat composition can be dispersed in a solvent to form a dilute coating composition. The amount of solids in the coating composition is typically at least 20 wt-% and usually no greater than about 50 wt-%. For some optical substrate such as polycarbonate, acrylic, cellulose acetate, and cellulose triacetate, it is preferred to employ an alcohol based solvent including for example methanol, ethyl alcohol, isopropyl alcohol, propanol, etc. as well as glycol ethers such as propylene glycol monomethyl ether or ethylene glycol monomethyl ether, etc. For such optical substrates, the coating compositions may contain predominantly alcohol solvent(s). For other uses, however, alcohol based solvent(s) may be combined with other (i.e. non-alcohol) solvents.
Thin coating layers can be applied to the optical substrate using a variety of techniques, including dip coating, forward and reverse roll coating, wire wound rod coating, and die coating. Die coaters include knife coaters, slot coaters, slide coaters, fluid bearing coaters, slide curtain coaters, drop die curtain coaters, and extrusion coaters among others. Many types of die coaters are described in the literature such as by Edward Cohen and Edgar Gutoff, Modern Coating and Drying Technology, VCH Publishers, NY 1992, ISBN 3-527-28246-7 and Gutoff and Cohen, Coating and Drying Defects: Troubleshooting Operating Problems, Wiley Interscience, NY ISBN 0-471-59810-0.
A die coater generally refers to an apparatus that utilizes a first die block and a second die block to form a manifold cavity and a die slot. The coating fluid, under pressure, flows through the manifold cavity and out the coating slot to form a ribbon of coating material. Coatings can be applied as a single layer or as two or more superimposed layers. Although it is usually convenient for the substrate to be in the form of a continuous web, the substrate may also be a succession of discrete sheets.
The term “optical display”, or “display panel”, can refer to any conventional optical displays, including but not limited to multi-character multi-line displays such as liquid crystal displays (“LCDs”), plasma displays, front and rear projection displays, cathode ray tubes (“CRTs”), and signage, as well as single-character or binary displays such as light emitting diodes (“LEDs”), signal lamps, and switches. The exposed surface of such display panels may be referred to as a “lens.” The invention is particularly useful for displays having a viewing surface that is susceptible to being touched or contacted by ink pens, markers and other marking devices, wiping cloths, paper items and the like. The protective coatings of the invention can be employed in a variety of portable and non-portable information display articles. These articles include PDAs, cell phones (including combination PDA/cell phones), LCD televisions (direct lit and edge lit), touch sensitive screens, wrist watches, car navigation systems, global positioning systems, depth finders, calculators, electronic books, CD and DVD players, projection television screens, computer monitors, notebook computer displays, instrument gauges, instrument panel covers, signage such as graphic displays and the like. The viewing surfaces can have any conventional size and shape and can be planar or non-planar, although flat panel displays are preferred. The coating composition or coated film, can be employed on a variety of other articles as well such as for example camera lenses, eyeglass lenses, binocular lenses, mirrors, retroreflective sheeting, automobile windows, building windows, train windows, boat windows, aircraft windows, vehicle headlamps and taillights, display cases, road pavement markers (e.g. raised) and pavement marking tapes, overhead projectors, stereo cabinet doors, stereo covers, watch covers, as well as optical and magneto-optical recording disks, and the like.
A variety of substrates can be utilized in the articles of the invention. Suitable substrate materials include glass as well as thermosetting or thermoplastic polymers such as polycarbonate, poly(meth)acrylate (e.g., polymethyl methacrylate or “PMMA”), polyolefins (e.g., polypropylene or “PP”), polyurethane, polyesters (e.g., polyethylene terephthalate or “PET”), polyamides, polyimides, phenolic resins, cellulose diacetate, cellulose triacetate, polystyrene, styrene-acrylonitrile copolymers, epoxies, and the like. Typically the substrate will be chosen based in part on the desired optical and mechanical properties for the intended use. Such mechanical properties typically will include flexibility, dimensional stability and impact resistance. The substrate thickness typically also will depend on the intended use. For most applications, a substrate thickness of less than about 0.5 mm is preferred, and is more preferably about 0.02 to about 0.2 mm. Self-supporting polymeric films are preferred. Films made from polyesters such as PET or polyolefins such as PP (polypropylene), PE (polyethylene) and PVC (polyvinyl chloride) are particularly preferred. The polymeric material can be formed into a film using conventional filmmaking techniques such as by extrusion and optional uniaxial or biaxial orientation of the extruded film. The substrate can be treated to improve adhesion between the substrate and the hardcoat layer, e.g., chemical treatment, corona treatment such as air or nitrogen corona, plasma, flame, or actinic radiation. If desired, an optional tie layer or primer can be applied to the substrate and/or hardcoat layer to increase the interlayer adhesion.
Various light transmissive optical films are known including but not limited to, multilayer optical films, microstructured films such as retroreflective sheeting and brightness enhancing films, (e.g. reflective or absorbing) polarizing films, diffusive films, as well as (e.g. biaxial) retarder films and compensator films such as described in U.S. Patent Application Publication No. 2004/0184150.
As described is U.S. Patent Application Publication 2003/0217806, multilayer optical films provide desirable transmission and/or reflection properties at least partially by an arrangement of microlayers of differing refractive index. The microlayers have different refractive index characteristics so that some light is reflected at interfaces between adjacent microlayers. The microlayers are sufficiently thin so that light reflected at a plurality of the interfaces undergoes constructive or destructive interference in order to give the film body the desired reflective or transmissive properties. For optical films designed to reflect light at ultraviolet, visible, or near-infrared wavelengths, each microlayer generally has an optical thickness (i.e., a physical thickness multiplied by refractive index) of less than about 1 μm. However, thicker layers can also be included, such as skin layers at the outer surfaces of the film, or protective boundary layers disposed within the film that separate packets of microlayers. Multilayer optical film bodies can also comprise one or more thick adhesive layers to bond two or more sheets of multilayer optical film in a laminate.
Further details of suitable multilayer optical films and related constructions can be found in U.S. Pat. No. 5,882,774 (Jonza et al.), and PCT Publications WO 95/17303 (Ouderkirk et al.) and WO 99/39224 (Ouderkirk et al.). Polymeric multilayer optical films and film bodies can comprise additional layers and coatings selected for their optical, mechanical, and/or chemical properties. See U.S. Pat. No. 6,368,699 (Gilbert et al.). The polymeric films and film bodies can also comprise inorganic layers, such as metal or metal oxide coatings or layers
Various permanent and removable grade adhesive compositions may be coated on the opposite side (i.e. to the hardcoat) of the substrate so the article can be easily mounted to a display surface. Suitable adhesive compositions include (e.g. hydrogenated) block copolymers such as those commercially available from Kraton Polymers of Westhollow, Tex. under the trade designation “Kraton G-1657”, as well as other (e.g. similar) thermoplastic rubbers. Other exemplary adhesives include acrylic-based, urethane-based, silicone-based, and epoxy-based adhesives. Preferred adhesives are of sufficient optical quality and light stability such that the adhesive does not yellow with time or upon weather exposure so as to degrade the viewing quality of the optical display. The adhesive can be applied using a variety of known coating techniques such as transfer coating, knife coating, spin coating, die coating and the like. Exemplary adhesives are described in U.S. Patent Application Publication No. 2003/0012936. Several of such adhesives are commercially available from 3M Company, St. Paul, Minn. under the trade designations 8141, 8142, and 8161.

Glossary

For the following defined terms, these definitions shall be applied, unless a different definition is given in the claims or elsewhere in the specification.
“Free-radically polymerizable” refers to the ability of monomers, oligomers, polymers or the like to participate in crosslinking reactions upon exposure to a suitable source of free radicals.
“(Meth)acryl” refers to functional groups including acrylates, methacrylates, acrylamides, methacrylamides, alpha-fluoroacrylates, thioacrylates and thio-methacrylates. A preferred (meth)acryl group is acrylate.
“Monovalent perfluoropolyether moiety” refers to a perfluoropolyether chain having one end terminated by a perfluoroalkyl group.
Unless otherwise noted, “HFPO-” refers to the end group F(CF(CF₃)CF₂O)aCF(CF₃)— of the methyl ester F(CF(CF₃)CF₂O)aCF(CF₃)C(O)OCH3, wherein “a” averages 2 to 15. In some embodiments, a averages between 3 and 10 or a averages between 5 and 8. Such species generally exist as a distribution or mixture of oligomers with a range of values for a, so that the average value of a may be non-integer. In one embodiment a averages 6.2. This methyl ester has an average molecular weight of 1,211 g/mol, and can be prepared according to the method reported in U.S. Pat. No. 3,250,808 (Moore et al.), the disclosure of which is incorporated herein by reference, with purification by fractional distillation.
The recitation of numerical ranges by endpoints includes all numbers subsumed within the range (e.g. the range 1 to 10 includes 1, 1.5, 3.33, and 10).
Objects and advantages of this invention are further illustrated by the following examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this invention.

EXAMPLES

Test Methods

1. Spots: The number of spots was determined visually in a 25 cm²area by counting the number of spots with the coating held against a black background. When the composition includes a particulate matting agent such as silica, the spots are white in appearance and can be more easily detected.
2. Contact Angle: Measurements were made using deionized water filtered through a filtration system obtained from Millipore Corporation (Billerica, Mass.), on a PgX Goniometer contact angle analyzer available as product number PGX from FIBRO System AB, Sweden. Reported values are the averages of measurements on at least three drops. Drop volumes were 5 μL for static measurements.
3. Durability of Ink Repellency was assessed using a modified Oscillating Sand Method (ASTM F 735-94). An orbital shaker was used (VWR DS-500E, from VWR Bristol, Conn.). A disk of diameter 89 mm was cut from the sample, placed in a 16 ounce jar lid (jar W216922 from Wheaton, Millville, N.J.), and covered with 40 grams of 20-30 mesh Ottawa sand (VWR, Bristol, Conn.). The jar was capped and placed in the shaker set at 250 rpm for 5 minutes. After shaking, a Sharpie permanent marker was used to draw a line across the diameter of the disk surface. The portion of the ink line that did not bead up was measured. A measure of 89 mm is equal to 100% ink repellency loss; a measure of 0 mm would be perfect durability or 0% ink repellency (IR) loss.

Synthesis of Perfluoropolyether Alcohol Starting Materials

HFPO—C(O)N(H)CH₂CH₂OH of different molecular weights (938.5, 1314, 1344, and 1547.2) were made by a procedure similar to that described in U.S. Publication No. 2004-0077775, (Docket Number 57823), entitled “Fluorochemical Composition Comprising a Fluorinated Polymer and Treatment of a Fibrous Substrate Therewith,” filed on May 24, 2002, for Synthesis of HFPO-oligomer alcohols with the exception that HFPO methyl ester F(CF(CF₃)CF₂O)aCF(CF₃)C(O)CH₃with a=6.2 was replaced with F(CF(CF3)CF2O)aCF(CF3)C(O)OCH3 wherein a=4.41, 6.67, 6.85, and 8.07 respectively.
The methyl ester material for preparation of the alcohol can be prepared according to the method reported in U.S. Pat. No. 3,250,808 (Moore et al.), the disclosure of which is incorporated herein by reference, with purification by fractional distillation.
1. HFPO—C(O)N(H)(CH₂CH₂O)₃H, MW 1329 was prepared according to the procedures for HFPO—C(O)N(H)CH₂CH₂OH, using F(CF(CF₃)CF₂O)aCF(CF₃)C(O)CH₃with a=6.2 (1211 MW) and substituting H₂N(CH₂CH₂O)₃H for H₂NCH₂CH₂OH.
2. HFPO—C(O)N(H)(CH₂)₆OH, MW 1297 was prepared according to the procedures for HFPO—C(O)N(H)CH₂CH₂OH, using F(CF(CF₃)CF₂O)aCF(CF₃)C(O)CH₃with a=6.2 (1211 MW) and substituting H₂N(CH₂)₆OH for H₂NCH₂CH₂OH
Polyisocyanate was obtained from Bayer Polymers LLC, of Pittsburgh, Pa. under the trade designation “Desmodur N100”. (“DesN100”)
Polyisocyanate was obtained from Bayer Polymers LLC, of Pittsburgh, Pa. under the trade designation “Desmodur N3300”. (“DesN3300”)
Pentaerythritol triacrylate (“PET3A”), under the trade designation “SR444C”, was obtained from Sartomer Company of Exton, Pa.
2,6-di-t-butyl-4-methylphenol (BHT) and dibutyltin dilaurate (DBTDL) are each available from Sigma Aldrich of Milwaukee, Wis.

Synthesis of Perfluoropolyether Urethane Multiacrylate

Example 1

Preparation of Des N100/0.85 PET3A/0.10 HFPO—C(O)NHCH₂CH₂OH/0.10 C₁₈H₃₇(OCH₂CH₂)₁₀OH

A 500 ml roundbottom flask equipped with magnetic stir bar was charged with 25.0 g (0.131 eq, 191 EW, 1.0 mole fraction) Des N100, 106.75 g methyl ethyl ketone (MEK), and 0.05 g BHT. The reaction was swirled to dissolve all the reactants, the flask was placed in a oil bath at 55 degrees Celsius, and fitted with a condenser under dry air. Sixty-five microliters of a 10% dibutyltin dilaurate solution in MEK was added to the reaction. Over 20 min, 17.59 g (0.0131 eq, 1344 EW, 0.10 mole fraction)
F(CF(CF₃)CF₂O)_6.85CF(CF₃)C(O)NHCH₂CH₂OH was added to the reaction via addition funnel. Two hours after the addition was complete, 9.07 g (0.0131 eq, 692.6 EW, 0.10 mole fraction) C₁₈H₃₇(OCH₂CH₂)₁₀OH (Brij 76) was added over 20 min. After reaction overnight, the following afternoon, 54.99 g (0.1115 eq, at 494.3 EW, 0.85 mole fraction) of Sartomer SR444C was added in one portion to the reaction which was allowed to proceed overnight. (The actual OH equivalent weight of the SR444C was 421.8, but 494.3 is used in calculations for all lots of SR444C, so that for any given material made, the weight percentage of SR444C will remain constant). The reaction was monitored by FTIR and initially showed an isocyanate absorption at 2273 cm⁻¹. This absorption was gone after reaction overnight, and 7.40 g of MEK was added to compensate for MEK lost during the reaction to adjust the final solids to 50% solids.
The perfluoropolyether urethane multiacrylates of Preparations 2-14, C1 and C2 were made by substantially the same procedure with 1.0 mole fraction (Des N100) isocyanate, the HFPO-alcohol at 0.10 mole fraction and each of the modifying alcohols at the mole fractions indicated in column 5 of the following Table 1. The HFPO—C(O)NHCH₂CH₂OH amidol of 1344 molecular weight was used for Example numbers C1, C3, 2, 3, 4, 5; whereas the HFPO—C(O)NHCH₂CH₂OH amidol of 1314 molecular weight was used for C2.


				PET3A/
				Alcohol
Ex.	Trade		Modifying Alcohol	Mole
No.	Designation	Supplier, location	Molecular Weight	Fraction

C1			None	0.95/0.0
C2		Aldrich,	HO(CH₂)₁₀OH	0.75/0.2
		St. Louis, MO	1–10 decane diol Mn = 174.3 g/mole
C3	Bisomer	Cognis, Cincinnati,	HO(CH₂CH₂O)₆C(O)CH═C₂	0.75/0.2
	PEA6	OH	Polyethylene glycol (6) monoacrylate
2	MA-100	Nippon Nyukazai,	HO(CH₂CH₂O)₁₀C(O)CH(CH₃)═CH2	0.85/0.1
		Tokyo, Japan	Hydroxyl alkylene oxide methacrylate
			Mn = 517 g/mole
3	NOVEL II	Sasol North	50:50 blend of	0.85/0.1
	810-10-10	America, Huston,	HO—(CH₂CH₂O)₁₀C₈H₁₇and
		TX.	HO—(CH₂CH₂O)₁₀C₁₀H₂₁
			Mn = 592.4 g/mole
4	CALGENE	Lambent	C₁₁H₂₃C(O)(CH₂CH₂O)₁₀OH	0.85/0.1
	40-L	Technologies,	Mn = 640 g/mole
		Gurnee, IL
5	Brij 78	Uniqema, New	C₁₈H₃₇(OCH₂CH₂)₂₀OH	0.85/0.1
		Castle, DE	Mn = 1058.5 g/mole

Ex. 6 and C4

1.0 DES N3300/PET3A/0.1 HFPOC(O)NHCH₂CH₂OH/C₁₈H₃₇(OCH₂CH₂)₂₀OH

Brij 78 at 50% solids in MEK. Both made with SR444C 421.8 EW., HFPOC(O)NHCH₂CH₂OH MW 1314, DES N3300 has an equivalent weight of 193.


	Example No.	PET3A/Alcohol Mole Fraction

	C4	0.95/0.0
	6	0.85/0.10

Ex. 7 and C5

1.0 DES N100/PET3A/0.1 HFPOC(O)NHCH₂CH₂OH C₁₈H₃₇(OCH₂CH₂)₂₀OH

Brij 78 at 50% solids in MEK. Both made with SR444C 421.8 EW., HFPOC(O)NHCH₂CH₂OH MW 938.5.


	Example No.	PET3A/Alcohol Mole Fraction

	C5	0.95/0.0
	7	0.85/0.10

Ex. 8 and C6

1.0 DES N100/PET3A/0.1 HFPOC(O)NH(CH₂CH₂O)₃H/C₁₈H₃₇(OCH₂CH₂)₂₀OH

Brij 78 at 50% solids in MEK.
Both made with SR444C 421.8 EW., HFPOC(O)NH(CH₂CH₂O)₃H MW 1329


	Example No.	PET3A/Alcohol Mole Fraction

	C6	0.95/0.0
	8	0.85/0.10

Ex. 9 and 10

1.0 DES N100/0.1 PET3A/0.1 HFPOC(O)NHCH₂CH₂OH/Modifying Alcohol

at 50% solids in MEK. Both made with SR444C 421.8 EW., HFPOC(O)NHCH₂CH₂OH MW 1314


				PET3A/
				Alcohol
	Trade	Supplier,	Modifying Alcohol,	Mole
Example No.	Designation	location	Molecular Weight	Fraction

9	“Carbowax	Dow Chemical	CH₃—(OCH₂CH₂)₁₃—OH	0.85/0.1
	MPEG 550”	Co., Midland, MI	Mn = 553 g/mole
10	“Carbowax	Dow Chemical	H—(OCH₂CH₂)₂₀—OH	0.85/0.20
	PEG 900”	Co.,	Mn = 900 g/mole
		Midland, MI

The perfluoropolyether urethane multiacrylates of Examples 11-12 and C7 and C8 were made by substantially the same procedure with 1.0 mole fraction (Des N100) isocyanate and the HFPO-alcohol (MW=1314) amounts indicated in column 2 and the modifying alcohols indicated in column 3, at the ew amounts indicated in column 4 of the following Table 3:


Example	HFPO		PET3A/Alcohol
No.	Mole fraction	Modifying Alcohol	Mole Fractions

C7	0.25	None	0.8/0.0
11	0.25	C₁₈H₃₇(OCH₂CH₂)₂₀OH	0.65/0.15
		Brij 78
12	0.25	C₁₈H₃₇(OCH₂CH₂)₂₀OH	0.55/0.25
		Brij 78

Ex. 13 and C8

1.0 DES N100/PET3A/0.1 HFPOC(O)NHCH₂CH₂OH/C₁₈H₃₇(OCH₂CH₂)₂₀OH

Brij 78 at 50% solids in MEK. Both made with SR444C 421.8 EW., HFPOC(O)NHCH₂CH₂OH MW 1547


	Example	PET3A/Alcohol
	No.	Mole Fraction

	C8	0.95/0.0
	13	0.85/0.10

Ceramer Hardcoat Comprising the Perfluoropolyether Urethane Multiacrylates

The ceramer hardcoat base compositions (“HCB-1”, “HCB-2” and “HCB-3”) used in the examples were made as described in column 10, line 25-39 and Example 1 of U.S. Pat. No. 5,677,050 to Bilkadi, et al. with the following (wt-% solids) additions:


Material	HCB-1	HCB-2	HCB-3

Example 1, No. 5,677,050 (solids)	94.4
Syloid C803 (silica)	2.8	2.75	2.7
Disperbyk 163 (dispersant)	2.8	2.75	2.7
Sartomer SR 295		46.75
Sartomer SR 238		46.75
Irgacure 819		1.0
SM Zirconia			74.1
Irgacure 184			1.4
Sartomer 399			19.1

Syloid C 803 is a fine silica from W.R. Grace and Co., Columbia, Md. Disperbyk 163 is a dispersant from Byk-Chemie USA, Wallingford, Conn. Irgacure 819 and 184 are photoinitiators from Ciba Specialty Chemicals, Tarrytown, N.Y. Sartomer SR 295, SR238, SR399 are all multifunctional acrylate monomers from Sartomer Corp., West Chester, Pa.
ZrO₂sols (40.8% solids in water) was prepared were prepared in accordance with the procedures described in U.S. patent application Ser. No. 11/079,832 filed Mar. 14, 2005 that claims priority to U.S. patent application Ser. No. 11/078,468 filed Mar. 11, 2005. The resulting ZrO₂sols were evaluated with Photo Correlation Spectroscopy (PCS), X-Ray Diffraction and Thermal Gravimetric Analysis as described in U.S. patent application Ser. Nos. 11/079,832 and 11/078,468. The ZrO₂sols used in the examples had properties in the ranges that follow:


	PCS Data

	Intensity	Volume-	(Intensity-
Dispersion	avg size	avg size	avg)/(Volume-
Index	(nm)	(nm)	avg)

1.0–2.4	23.0–37.0	8.0–18.8	1.84–2.97


Relative Intensities	Apparent Crystallite Size (nm)		Weighted

Cubic/		(C, T)	M	M	Avg M		Avg XRD
Tetragonal	Monoclinic	(1 1 1)	(−1 1 1)	(1 1 1)	Size	% C/T	Size

100	6–12	7.0–8.5	3.0–6.0	4.0–11.0	4.5–8.3	89%–94%	7.0–8.4

Surface Modified Zirconia Nanoparticles (SM Zirconia)

20.4 lbs of an aqueous dispersion of 10 nm zirconia nanoparticles (40.8% solids in water) was added to a 10 gallon reactor. 12.9 lbs additional water and 33.3 lbs 1-methoxy-2-propanol were added to the reactor with stirring. 2.5 lbs of 3-methacryloxypropyltrimethoxysilane was added slowly to the reactor with stirring. 0.021 lbs of a 5% solution in water of Prostab 5198 was added to the reactor with stirring. The mixture was stirred 18 hours at 80° C.
The reaction mixture was heated under vacuum (24-40 torr) and the 1-methoxy-2-propanol/water azeotrope was distilled off to remove substantially all of the water, while slowly adding 70.5 lbs of additional 1-methoxy-2-propanol. 0.4 lbs of 30% ammonium hydroxide was added to the reaction mixture, then the reaction was concentrated to 59.2% solids by distilling off 1-methoxy-2-propanol. The surface modification reaction resulted in a mixture containing 59.2% surface modified zirconia (ZrO₂-SM), by weight, in 1-methoxy-2-propanol. The final mixture was filtered through a 1 micron filter.

Coating and Curing of Hardcoat Composition on Optical Film

Solutions were prepared at 30% solids in a solvent blend of 1:1 isopropanol:propylene glycol methyl ether and coated to yield a dry thickness of about 4 microns using a number 12 wire wound rod onto 5-mil Melinex 618 film. The coatings were dried in a 100 degree Celsius oven for 2 minutes and then placed on a conveyer belt coupled to a ultraviolet (“UV”) light curing device and UV cured under nitrogen using a Fusion 500 watt H bulb at 30 ft/min. The values reported in the Tables refer to the percent solids of each component of the dried coating. The coatings were then visually inspected for surface smoothness (dewetting). The coatings were also tested for durability of ink repellency. Results are shown in Tables 4 and 5.

TABLE 4

Hardcoat Composition Comprising Perfluoropolyether (PFPE)
Urethane Additive

Wt-%
solids	Wt-%
HCB-1	Solids		PFPE	Spots
in	PFPE		Urethane	(per	Contact
coating	Urethane	Sample #	Example No.	cm²)	Angle

HC-1	99.4	0.6	27	C1	1.2	100
HC-2	99.4	0.6	91	C2	0.32	100
HC-3	99.4	0.6	38	C3	0.36	105
Ex. 14	99.4	0.6	42	2	0.2	105
Ex. 15	99.4	0.6	47	1	0.04	102
Ex. 16	99.4	0.6	48	3	0.08	102
Ex. 17	99.4	0.6	49	4	0.04	105
Ex. 18	99.4	0.6	53	5	0	103
HC-4	99.4	0.6	70	C4	1.6	104
Ex. 19	99.4	0.6	71	6	0.8	102
HC-5	99.4	0.6	72	C5	0.04	95
Ex. 20	99.4	0.6	73	7	0.04	94
HC-6	99.4	0.6	74	C6	0.28	103
Ex. 21	99.4	0.6	75	8	0.04	102
Ex. 22	99.4	0.6	78	9	0.04	105
Ex. 23	99.4	0.6	79	10	0.12	100
HC-7	99.4	0.6	82	C7	2.8	103
Ex. 24	99.4	0.6	83	11	2.8	103
Ex. 25	99.4	0.6	84	12	0.88	94
HC-8	99.4	0.6	85	C8	0.16	106
Ex. 26	99.4	0.6	86	13	0.04	102
	HCB-2
HC-9	99.4	0.6	27	C1	0.36	102
Ex. 27	99.4	0.6	53	5	0.16	93
	HCB-3
HC-10	99.4	0.6	27	C1	0.6	103
Ex. 28	99.4	0.6	53	5	0.24	94

Examples 16-18 were tested for Durability of Ink Repellency.
The results are as follows:


	Durability of Ink
	Repellency
	(% loss)

	HC1	0
	Comparative
	Example 16	0
	Example 17	11
	Example 18	34

Claims

1. An optical display comprising:

an optical substrate having a surface layer comprising the reaction product of a polymerizable mixture comprising

at least one perfluoropolyether urethane polymeric material comprising at least two free-radically polymerizable groups and greater than 6 ethylene oxide repeat units;

at least one non-fluorinated crosslinker comprising at least two free-radially polymerizable groups.

2. The optical display of claim 1 wherein the perfluoropolyether urethane polymer comprises at least two (meth)acrylate groups.

3. The optical display of claim 2 wherein the perfluoropolyether urethane comprises a terminal group having at least two (meth)acrylate groups.

4. The optical display of claim 1 wherein the perfluoropolyether urethane comprises a monovalent perfluoropolyether moiety.

5. The optical display of claim 1 wherein the perfluoropolyether moiety is F(CF(CF₃)CF₂O)aCF(CF₃)— and a ranges from 4 to 15.

6. The optical display of claim 1 wherein the non-fluorinated crosslinker comprise at least three free-radically polymerizable groups.

7. The optical display of claim 1 wherein the substrate is selected from polycarbonate, acrylic, cellulose acetate, and cellulose triacetate.

8. The optical display of claim 1 wherein the surface layer further comprises inorganic oxide particles.

9. The optical display of claim 1 wherein a hardcoat layer comprising inorganic oxide particles is disposed between the substrate and the surface layer.

10. An optical substrate having a surface layer comprising the reaction product of a polymerizable mixture comprising

11. A multifunctional perfluoropolyether urethane composition having the general formula

Ri-(NHC(O)XQRf), —(NHC(O)OQ(A)p), —(NHC(O)X^j(C₂H₄O)_jR^j

wherein Ri is a residue of a multi-isocyanate;

Q is independently a straight chain, branched chain, or cyclic-containing connecting group having a valency at least 2;

Rf is a monovalent perfluoropolyether moiety composed of groups comprising the formula F(RfcO)xCdF2d-, wherein each Rfc independently represents a fluorinated alkylene group having from 1 to 6 carbon atoms, each x independently represents an integer greater than or equal to 2, and wherein d is an integer from 1 to 6;

A is a (meth)acryl functional group —XC(O)C(R2)=CH2, where R2 is a lower alkyl of 1 to 4 carbon atoms or H or F;

p is 2 to 6;

j ranges from 7 to 40; and

R^jis H, —C(O)C(R₂)═CH₂, where R₂is a lower alkyl of 1 to 4 carbon atoms or H or F, or a group selected from alkyl, aryl, alkaryl, aralkyl, optionally substituted with a heteroatom, heteoratom functional group, or a (meth)acryl functional group.

12. The composition of claim 11 with the proviso that when X is O, Q is not methylene.

13. The composition of claim 11 wherein Q is selected from an alkylene having at least two carbon atoms, arylene, aralkylene, and alkarylene.

14. The composition of claim 13 wherein Q comprises a heteroatom selected from O, N, and S.

15. The composition of claim 14 wherein Q comprise a nitrogen containing group.

16. The composition of claim 15 wherein Q contains an amide group.

17. The composition of claim 16 wherein Q is selected from —C(O)NHCH₂CH₂—, —C(O)NH(CH₂)₆—, and —C(O)NH(CH₂CH₂O)CH₂CH₂—.

18. A free-radially polymerizable composition comprising a mixture of reaction products of

i) at least one polyisocyanate;

ii) at least one isocyanate reactive perfluoropolyether compound;

iii) at least one isocyanate reactive compound comprising greater than 6 repeat units of ethylene oxide; and

iv) at least one isocyanate reactive non-fluorinated crosslinker comprising at least two free-radically polymerizable groups.

19. The composition of claim 18 dispersed in an alcohol-containing solvent.

20. The free-radically polymerizable coating of claim 24 wherein ii) and iii) comprise alcohol isocyanate reactive groups.