Patent Application
20200324527
The present disclosure broadly relates to composite films, covers for electronic devices, and methods of making the same.
Covers for electronic devices, including transparent thermoformed covers for electronic displays, are prone to surface damage such as gouging and scuffing that may occur during handling and use. Such damage can detract from performance and/or aesthetic appearance of the electronic device.
It would be desirable to have materials and methods for protecting covers for electronic devices from physical damage such as, for example, gouging and/or scuffing. It would further be desirable that such materials and methods would be amenable to shaping and post-forming processes used to incorporate them into various articles.
Accordingly, in one aspect, the present disclosure provides a composite film comprising:
a first unitary thermoplastic polymer film having first and second opposed major surfaces;
a low surface energy abrasion resistant layer disposed on the first major surface of the first unitary thermoplastic polymer film, wherein the low surface energy abrasion resistant layer comprises an at least partially cured curable composition, the curable composition comprising components:
a first adhesive layer proximate and securely bonded to the second major surface of the first unitary thermoplastic polymer film;
a second unitary thermoplastic polymer film proximate having two opposed major surfaces and securely bonded to the first adhesive layer; and
a second adhesive layer proximate and securely bonded to the second unitary thermoplastic polymer film opposite the first adhesive layer.
In a second aspect, the present disclosure provides a protective cover for an electronic device, the protective cover comprising:
a first unitary thermoplastic polymer film having first and second opposed major surfaces;
a low surface energy abrasion resistant layer disposed on the first major surface of the first unitary thermoplastic polymer film, wherein the low surface energy abrasion resistant layer comprises an at least partially cured curable composition, the curable composition comprising components:
a first adhesive layer proximate and securely bonded to the second major surface of the first unitary thermoplastic polymer film,
wherein the protective cover comprises a central planar section having first and second opposed major surfaces, wherein the central planar section is bounded by at least two linear side sections, wherein the at least two linear side sections extend out of plane from the central planar section to define inner and outer surfaces of the protective cover, and wherein the low surface energy abrasion resistant layer is disposed on the outer surface of the central planar section.
In yet another aspect, the present disclosure provides a method of making a protective cover for an electronic device, the method comprising:
thermoforming a composite film to provide a protective cover comprising a central planar section having first and second opposed major surfaces, wherein the central planar section is bounded by at least two linear side sections, and wherein the composite film comprises:
a first unitary thermoplastic polymer film having first and second opposed major surfaces;
a low surface energy abrasion resistant layer disposed on the first major surface of the first unitary thermoplastic polymer film, wherein the low surface energy abrasion resistant layer comprises an at least partially cured curable composition, the curable composition comprising components:
a first adhesive layer proximate and securely bonded to the second major surface of the first unitary thermoplastic polymer film,
wherein the at least two linear side sections extend out of plane from the central planar section to define inner and outer surfaces of the protective cover, and wherein the low surface energy abrasion resistant layer is disposed on at least a portion of the outer surface.
As used herein:
The term “carbamylene” refers to the divalent group
The prefix “(meth)acryl” refers to methacryl and/or acryl;
“transparent” means having the property of transmitting rays of light through its substance so that bodies situated beyond or behind can be distinctly seen by an unaided human eye; and
“urethane (meth)acrylate compound” means a compound having at least one (preferably at least 2, 3, 4, or more) carbamylene group (i.e., —NHC(═O)O—) and at least one (meth)acryl group.
Features and advantages of the present disclosure will be further understood upon consideration of the detailed description as well as the appended claims.
Repeated use of reference characters in the specification and drawings is intended to represent the same or analogous features or elements of the disclosure. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art, which fall within the scope and spirit of the principles of the disclosure. The figures may not be drawn to scale.
Composite films according to the present disclosure include various components. Referring now to
First adhesive layer 130 is proximate and securely bonded to second major surface 114. Second unitary thermoplastic polymer film 140 has two opposed major surfaces (142, 144) and is securely bonded to first adhesive layer 130. Second adhesive layer 150 is proximate and securely bonded to second unitary thermoplastic polymer film 140 opposite first adhesive layer 130. Optional releasable liner 160 is releasably adhered to the second adhesive layer.
Composite films according to the present disclosure and related subassemblies thereof may be useful for making protective covers for electronic devices
Referring now to
Two embodiments of a thermoformed protective cover are shown in
Referring now to
Curable compositions that may be at least partially cured to provide the low surface energy abrasion resistant layer comprise, based on the total weight of components a) to d):
a) 70 to 95 weight percent of urethane (meth)acrylate compound (i.e., one or more urethane (meth)acrylate compounds) having an average (meth)acrylate functionality of 3 to 9, preferably 3 to 7, and more preferably 3 to 6;
b) 2 to 20 weight percent (meth)acrylate monomer (i.e., one or more (meth)acrylates) having a (meth)acrylate functionality of 1 to 2, preferably 2;
c) 0.5 to 2 weight percent of silicone (meth)acrylate (i.e., one or more silicone (meth)acrylates), preferably having 1 or 2 (meth)acrylate groups per silicone (meth)acrylate molecule;
d) optional effective amount of photoinitiator (i.e., one or more photoinitiators), preferably 1 to 3 photoinitiators;
e) optional solvent (i.e., one or more solvents), preferably organic solvent; and
f) optional alpha alumina particles having a Dv50 of from 0.1 to 1 micron.
The urethane (meth)acrylate compound contributes to the conformability and flexibility of the cured composition, and hence its suitability for thermoforming. Exemplary urethane (meth)acrylate compounds having an average (meth)acrylate functionality of 3 to 9 are available from commercial sources, and/or can be prepared according to known methods.
Commercially available urethane (meth)acrylate compounds include EBECRYL 264 aliphatic urethane triacrylate, EBECRYL 265 aliphatic urethane triacrylate, EBECRYL 1258 aliphatic urethane triacrylate, EBECRYL 4100 aliphatic urethane triacrylate, EBECRYL 4101 aliphatic urethane triacrylate, EBECRYL 8412 aliphatic urethane acrylate (trifunctional), EBECRYL 4654 aliphatic urethane triacrylate, EBECRYL 4666 aliphatic urethane triacrylate, EBECRYL 4738 aliphatic allophanate urethane triacrylate, EBECRYL 4740 aliphatic allophanate urethane triacrylate, EBECRYL 8405 aliphatic urethane tetraacrylate, EBECRYL 8604 aliphatic urethane tetraacrylate, EBECRYL 4500 aromatic urethane tetraacrylate, EBECRYL 4501 aromatic urethane tetraacrylate, EBECRYL 4200 aliphatic urethane tetraacrylate, EBECRYL 4201 aliphatic urethane tetraacrylate, EBECRYL 8702 aliphatic urethane hexaacrylate, EBECRYL 220 aromatic urethane hexaacrylate, EBECRYL 221 aromatic urethane hexaacrylate, EBECRYL 2221 aromatic urethane hexaacrylate, EBECRYL 2221 aromatic urethane hexaacrylate, EBECRYL 5129 aliphatic urethane hexaacrylate, EBECRYL 1290 aliphatic urethane hexaacrylate, EBECRYL 1291 aliphatic urethane hexaacrylate, EBECRYL 8301-R aliphatic urethane hexaacrylate, EBECRYL 8602 aliphatic urethane acrylate (nonafunctional), all from Allnex, Brussells, Belgium; and CN929 trifunctional urethane acrylate and CN9006 aliphatic urethane acrylate (hexafunctional) from Sartomer Co., Exton, Pa.
In some embodiments, the urethane (meth)acrylate compound can be synthesized by reacting a polyisocyanate compound with a hydroxyl-functional (meth)acrylate compound. A variety of polyisocyanates may be utilized in preparing the urethane (meth)acrylate compound. As used herein, the term “polyisocyanate” means any organic compound that has two or more reactive isocyanate (—NCO) groups in a single molecule such as, for example, diisocyanates, triisocyanates, tetraisocyanates, and mixtures thereof. For improved weathering and diminished yellowing the, urethane (meth)acrylate compound(s) employed herein are preferably aliphatic and therefore derived from an aliphatic polyisocyanate.
The urethane (meth)acrylate compound is preferably a reaction product of hexamethylene diisocyanate (HDI), such as available from Covestro LLC, Pittsburgh, Pa. as DESMODUR H, or a derivative thereof. These derivatives include, for example, polyisocyanates containing biuret groups, such as the biuret adduct of hexamethylene diisocyanate (HDI) available from Covestro LLC as DESMODUR N-100, polyisocyanates containing one or more isocyanurate rings
such as that available from Covestro LLC as DESMODUR N-3300, as well as polyisocyanates containing urethane groups, uretdione groups, carbodiimide groups, and/or allophanate groups. Yet another useful derivative, is a hexamethylene diisocyanate (HDI) trimer, available from Covestro LLC as DESMODUR N-3800. These derivatives are preferred as they are polymeric, exhibit very low vapor pressures and are substantially free of isocyanate monomer.
In some embodiments, the urethane (meth)acrylate compound is the reaction product of a polyisocyanate such as a hexamethylene diisocyanate (HDI) derivative having an —NCO (i.e., isocyanate group) content of at least 10 percent, at least 15 percent, or even at least 20 weight percent. In some cases, HDI or other polyisocyanate may be reacted with hydroxyl-functional (meth)acrylate compounds and polyols. The —NCO content of the polyisocyanate is preferably not greater than 50 weight percent. On some embodiments, the polyisocyanate typically has an equivalent weight of at least 80, 100, 120, 140, 160, 180, or even 200 grams/per —NCO group. The equivalent weight is typically no greater than 500, 450, or 400 grams/per —NCO group and in some embodiments no greater than 350, 300, or 250 grams/per —NCO group, although this is not a requirement.
When aliphatic polyisocyanates comprising a cyclic group such as an isophorone diisocyanate (IPDI) derivative are used, the resulting cured composition can be less flexible (e.g., have poor thermoformability) and poor abrasion resistance.
The polyisocyanate is reacted with a hydroxyl-functional acrylate compound having the formula HOQ(A)p; wherein Q is a divalent organic linking group, A is a (meth)acryl functional group —XC(═O)C(R2)═CH2 wherein X is O, S, or NR wherein R is H or C1-C4 alkyl, R2 is a lower alkyl of 1 to 4 carbon atoms or H; and p is 1 to 6. The —OH group reacts with the isocyanate group forming a urethane linkage.
In some embodiments, the polyisocyanate can be reacted with a diol acrylate, such as a compound of the formula HOQ(A)Q1Q(A)OH, wherein Q1 is a divalent linking group and A is a (meth)acryl functional group as previously described. Representative compounds include hydantoin hexaacrylate (HHA) (e.g., see Example 1 of U.S. Pat. No. 4,262,072 (Wendling et al.), and H2CH═C(CH3)C(═O)OCH2CH(OH)CH2O(CH2)4OCH2CH(OH)CH2OC(═O)C(CH3)═CH2.
Q and Q1 are independently a straight or branched chain or cycle-containing connecting group. Q can, for example, include a covalent bond, alkylene, arylene, aralkylene, or 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. In one embodiment, the hydroxyl-functional acrylate compounds used to prepare the urethane (meth)acrylate compound are monofunctional, such as in the case of hydroxyethyl acrylate, hydroxybutyl acrylate, and caprolactone monoacrylate, available as SR-495 from Sartomer Co. In this embodiment, p is 1.
In another embodiment, the hydroxyl-functional acrylate compounds used to prepare the urethane (meth)acrylate compound are multifunctional, such as the in the case of glycerol dimethacrylate, 1-(acryloxy)-3-(methacryloxy)-2-propanol, pentaerythritol triacrylate. In this embodiment, p is at least 2, at least 3, at least 4, at least 5, or at least 6.
In some embodiments, only monofunctional hydroxyl-functional acrylate compounds are utilized in the preparation of the urethane (meth)acrylate compound. In other embodiments, a combination of monofunctional and multifunctional hydroxyl-functional acrylate compounds are utilized in the preparation of the urethane (meth)acrylate compound. In some embodiments, the weight ratio of monofunctional hydroxyl-functional acrylate compound(s) to multifunctional hydroxyl-functional acrylate compound(s) ranges from 0.5:1 to 1:0.5. When the urethane (meth)acrylate compound is prepared from only multifunctional hydroxyl-functional acrylate compound(s), in some embodiments the resulting cured composition can be less flexible.
The average (meth)acrylate functionality is calculated in the following fashion. The functionality of the added acrylates for each compound is first calculated. For instance, the PE3 below is designated as 1.0 DESN100+0.25 HEA+0.75 PET3A. This means that the compound is the reaction product of 1 equivalent of isocyanate groups (as DESN100) and 0.25 hydroxyl equivalents of hydroxyethyl acrylate and 0.75 hydroxyl equivalents of PET3A. The HEA has 1 acrylate group per hydroxyl group and the PET3A has 3 acrylate groups per hydroxyl group. The functionality of added acrylates for this compound is then (0.25*1)+(0.75*3) or 2.5. The average (meth)acrylate functionality is found by multiplying the functionality of the added acrylates for each compound by the average functionality of the polyisocyanate. According to Covestro, the average functionality for DESN100 is 3.6, so the average (meth)acrylate functionality for the compound is at 2.5*3.6 or 9.
Other estimated average functionality of polyisocyanates for DESN3300, DESN3800, and DESZ4470BA are 3.5, 3.0, and 3.3 respectively.
In some embodiments, some of the isocyanate groups on the polyisocyanate can be reacted with a polyol such as, for example, an alkoxylated polyol available from Perstorp Holding AB, Sweden as Polyol 4800. Such polyols can have a hydroxyl number of 500 to 1000 mg KOH/g and a molecular weight ranging from at least 200 or 250 g/mole up to 500 g/mole.
In some embodiments, some of the isocyanate groups on the polyisocyanate can be reacted with a polyol such as 1,6-hexanediol.
Selection of reaction conditions used to react the polyisocyanate with (meth)acrylated alcohols, and choice of catalyst if any, will be apparent to those of skill in the art. Further examples can be found in the Examples section hereinbelow.
Useful (meth)acrylate monomers (which are preferably non-urethane, and preferably non-silicone, although this is not a requirement) have a (meth)acrylate functionality of 1 to 2. These monomers may function as diluents or solvents, as viscosity reducers, as binders when cured, and as crosslinking agents, for example. Examples of useful (meth)acrylates include mono(meth)acrylates such as octyl (meth)acrylate, nonylphenol ethoxylate (meth)acrylate, isononyl (meth)acrylate, isobornyl (meth)acrylate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, beta-carboxyethyl (meth)acrylate, isobutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, isodecyl (meth)acrylate, dodecyl(meth)acrylate, n-butyl (meth)acrylate, methyl (meth)acrylate, hexyl (meth)acrylate, (meth)acrylic acid, stearyl (meth)acrylate, hydroxy functional caprolactone ester (meth)acrylate, isooctyl (meth)acrylate, hydroxymethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxyisopropyl (meth)acrylate, hydroxybutyl(meth)acrylate, hydroxyisobutyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, and alkoxylated versions of the above (meth(acrylate monomers, such as alkoxylated tetrahydrofurfuryl (meth)acrylate and combinations thereof. Tetrahydrofurfuryl (meth)acrylate is preferred in some embodiments; di(meth)acrylates such as 1,6-hexanediol di(meth)acrylate, poly(ethylene glycol) di(meth)acrylates, polybutadiene di(meth)acrylates, polyurethane di(meth)acrylates, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, alkoxylated versions of the above di(meth)acrylates, and combinations thereof. Of these, 1,6-hexanediol diacrylate is preferred n some embodiments. (Meth)acrylate monomers having a functionality of 1 or 2 (e.g., as listed above) are widely commercially available.
Exemplary useful silicone (meth)acrylates include mono- and polyfunctional silicone (meth)acrylates. Of these, silicone poly(meth)acrylates may be preferred because the likelihood of unbound silicone (meth)acrylate after curing is generally reduced. Exemplary silicone (meth)acrylates include EBECRYL 350 silicone diacrylate and EBECRYL 1360 silicone hexaacrylate from Allnex, CN9800 aliphatic silicone acrylate and CN990 siliconized urethane acrylate compound from Sartomer Co., and TEGO RAD 2100, TEGO RAD 2250, and TEGO RAD 2500 silicone polyether acrylate from Evonik Industries, Parsippany, N.J.
The curable composition may optionally, but preferably, further comprise an effective amount of photoinitiator. By the term “effective amount” is meant an amount that is at least sufficient amount to cause curing of the curable composition under ambient conditions. It will be recognized that curing may be complete even though polymerizable (meth)acrylate groups remain.
Exemplary photoinitiators include α-cleavage photoinitiators such as benzoin and its derivatives such as α-methylbenzoin; α-phenylbenzoin; α-allylbenzoin; α-benzylbenzoin; benzoin ethers such as benzil dimethyl ketal (available as IRGACURE 651 from Ciba Specialty Chemicals, Tarrytown, N.Y.), benzoin methyl ether, benzoin ethyl ether, benzoin n-butyl ether; acetophenone and its derivatives such as 2-hydroxy-2-methyl-1-phenyl-1-propanone (available as DAROCUR 1173 from Ciba Specialty Chemicals) and 1-hydroxycyclohexyl phenyl ketone (available as IRGACURE 184 from Ciba Specialty Chemicals); 2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone (available as IRGACURE 907 from Ciba Specialty Chemicals); 2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone (available as IRGACURE 369 from Ciba Specialty Chemicals); titanium complexes such as bis(η5-2,4-cyclopentadien-1-yl)bis[2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl]titanium (available as CGI 784 DC from Ciba Specialty Chemicals); and mono- and bis-acylphosphines (available from Ciba Specialty Chemicals as IRGACURE 1700, IRGACURE 1800, IRGACURE 1850, and DAROCUR 4265). One useful photoinitiator, a difunctional alpha hydroxyketone, is available as ESACURE ONE from Lamberti S.p.A, Albizzate, Italy.
Desirably, if an acylphosphine or acylphosphine oxide photoinitiator is utilized, it is combined with a photoinitiator (e.g., 2-hydroxy-2-methyl-1-phenyl-1-propanone) having a high extinction coefficient at one or more wavelengths of the actinic radiation. Such combination typically facilitates surface cure while maintaining low levels of costly photoinitiator.
Other useful photoinitiators include: anthraquinones (e.g., anthraquinone, 2-ethylanthraquinone, 1-chloroanthraquinone, 1,4-dimethylanthraquinone, 1-methoxyanthraquinone) and benzophenone and its derivatives (e.g., phenoxybenzophenone, phenylbenzophenone).
The curable composition may contain optional solvent, generally organic solvent, although water/solvent blends may be used. Exemplary optional solvents include hydrocarbons or halogenated hydrocarbons (e.g., toluene, cyclohexane, petroleum ether, lower alcohols (e.g., methanol, ethanol, propanol, and isopropanol), esters of aliphatic acids (e.g., ethyl acetate), ethers (e.g., tetrahydrofuran), and ketones (e.g., acetone and methyl ethyl ketone). The solvents can be used singly or in admixture. One skilled in the art can readily determine which solvent to use, and its amount.
The curable composition may contain alpha alumina particles having a particle size distribution with a Dv50 of from 0.15 to 1 micron. If present, the curable composition preferably contains from 0.2 to 9 weight percent (preferably 0.2 to 3 weight percent) of alpha alumina particles based on the total weight of components a) and b). In some preferred embodiments, the alpha alumina particles have a particle size distribution with a Dv50 of from 0.2 to 0.3 micron. In some preferred embodiments, the alpha alumina particles have a polymodal distribution.
The alpha alumina particles comprise, preferably consist essentially of (e.g., are at least 99 weight percent), or even consist of, alumina in its alpha crystalline form. In some preferred embodiments, the alpha alumina particles have a particle size distribution with a Dv50 of greater than or equal to 0.21, 0.23, 0.25, 0.30, 0.40, or even 0.50 micron. In some preferred embodiments, the curable composition and the polymer composition may contain less than 8, 7, 6, 5, 4, 3, or even less than 2 weight percent of alpha alumina particles having a particle size distribution with a Dv50 of from 0.2 to 0.3 micron, based on the total weight of components a) and b).
The alpha alumina particles can be made by milling larger size alpha alumina, for example, using a ball mill or a jet mill. If using a ball mill the milling media preferably comprises, or even consists of, alpha alumina, although other milling media such as, for example, aluminum zirconate media may be used.
Alpha alumina particles, which may even be in the size range of having particle size distribution with a Dv50 of from 0.15 to 1 micron, can be readily obtained from commercial sources. Suppliers include US Research Nanomaterials, Inc., Houston, Tex.; Sisco Research Laboratories Pvt. Ltd., Mumbai, India; and Baikowski International Corp., Charlotte, N.C.
The curable composition may also contain one or more optional additional additives such as, for example, fillers, thickeners, tougheners, pigments, fibers, tackifiers, lubricants, wetting agents, surfactants, antifoaming agents, dyes, coupling agents, plasticizers, and suspending agents.
The first and second unitary thermoplastic films (which are preferably optically transparent although this is not a requirement) each independently comprise one or more thermoplastic polymers. The unitary thermoplastic films may be in sheet form or continuous (e.g., a web), and may have any thickness suitable for thermoforming. In some embodiments, one or both of the first and second unitary thermoplastic film has a thickness of from 25 microns to 3 mm, although this is not a requirement.
Useful thermoplastic polymers include, for example, polylactones (e.g., poly(pivalolactone) and poly(caprolactone)); polyurethanes (e.g., those derived from reaction of diisocyanates such as 1,5-naphthalene diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, 2,4-toluene diisocyanate, 4,4′-diphenylmethane diisocyanate, 3,3′-dimethyl-4,4′-diphenylmethane diisocyanate, 3,3′-dimethyl-4,4′-biphenyl diisocyanate, 4,4′-diphenylisopropylidene diisocyanate, 3,3′-dimethyl-4,4′-diphenyl diisocyanate, 3,3′-dimethyl-4,4′-diphenylmethane diisocyanate, 3,3′-dimethoxy-4,4′-biphenyl diisocyanate, dianisidine diisocyanate, toluidine diisocyanate, hexamethylene diisocyanate, or 4,4′-diisocyanatodiphenylmethane with linear long-chain diols such as poly(tetramethylene adipate), poly(ethylene adipate), poly(1,4-butylene adipate), poly(ethylene succinate), poly(2,3-butylenesuccinate), polyether diols); polycarbonates (e.g., poly(methane bis(4-phenyl) carbonate), poly(1,1-ether bis(4-phenyl)carbonate), poly(diphenylmethane bis(4-phenyl)carbonate), poly(1,1-cyclohexane bis(4-phenyl) carbonate), or poly(2,2-(bis4-hydroxyphenyl)propane) carbonate); polysulfones; polyether ether ketones; polyamides (e.g., poly(4-aminobutyric acid), poly(hexamethylene adipamide), poly(6-aminohexanoic acid), poly(m-xylylene adipamide), poly(p-xylylene sebacamide), poly(m-phenylene isophthalamide), and poly(p-phenylene terephthalamide)); polyesters (e.g., poly(ethylene azelate), poly(ethylene-1,5-naphthalate), poly(ethylene-2,6-naphthalate), poly(1,4-cyclohexane dimethylene terephthalate), poly(ethylene oxybenzoate), poly(para-hydroxy benzoate), poly(1,4-cyclohexylidene dimethylene terephthalate)(cis), poly(1,4-cyclohexylidene dimethylene terephthalate)(trans), polyethylene terephthalate, and polybutylene terephthalate); poly(arylene oxides) (e.g., poly(2,6-dimethyl-1,4-phenylene oxide) and poly(2,6-diphenyl-1,1-phenylene oxide)); polyetherimides; vinyl polymers and their copolymers (e.g., polyvinyl acetate, polyvinyl alcohol, polyvinyl chloride, polyvinyl butyral, polyvinylidene chloride, and ethylene-vinyl acetate copolymers); acrylic polymers (e.g., poly(ethyl acrylate), poly(n-butyl acrylate), poly(methyl methacrylate), poly(ethyl methacrylate), poly(n-butyl methacrylate), poly(n-propyl methacrylate), polyacrylamide, polyacrylonitrile, ethylene-ethyl acrylate copolymers, and ethylene-acrylic acid copolymers, poly(acrylonitrile-co-butadiene-co-styrene) and poly(styrene-co-acrylonitrile)); styrenic polymers (e.g., polystyrene, poly(styrene-co-maleic anhydride) polymers and their derivatives, methyl methacrylate-styrene copolymers, and methacrylated butadiene-styrene copolymers); polyolefins (e.g., polyethylene, polybutylene, polypropylene, chlorinated low density polyethylene, poly(4-methyl-1-pentene)); cellulose ester plastics (e.g., cellulose acetate, cellulose acetate butyrate, and cellulose propionate); polyarylene ethers (e.g., polyphenylene oxide); polyimides; polyvinylidene halides; aromatic polyketones; and polyacetals. Copolymers and/or combinations of these aforementioned polymers can also be used. Of these polycarbonates are typically preferred.
The curable composition may be coated onto a major surface of the first unitary polymer film by any suitable technique including, for example, spray coating, roll coating, gravure coating, slot coating, knife coating, bar coating, and dip coating. If optional solvent is present, it is typically at least substantially removed at this point (e.g., using a forced air oven or other heating means).
Next, the optionally at least partially dried, curable composition is at least partially cured, preferably fully cured to provide a, typically thermoformable, composite film. Curing may be accomplished using heat if the curable composition comprises a thermal initiator (e.g., a peroxide initiator), particulate radiation (e.g., e-beam), or photocuring (e.g., using ultraviolet and/or visible wavelengths of electromagnetic radiation). Techniques for such curing technologies are well-known in the art and are within the capability of the skilled artisan.
Subsequent layers of adhesive(s), optional second unitary polymer film, and optional release liner may be added using techniques known to those of skill in the art such as, for example, by lamination. Lamination can be accomplished by heating and/or pressure, more preferably using the first and option second adhesive layers. Preferably the adhesive layer are pressure-sensitive and/or hot melt adhesives. Exemplary pressure-sensitive adhesives include latex crepe, rosin, acrylic polymers, and copolymers including polyacrylate esters (e.g., poly(butyl acrylate)), vinyl ethers (e.g., poly(vinyl n-butyl ether)), alkyd adhesives, rubber adhesives (e.g., natural rubber, synthetic rubber, chlorinated rubber), and mixtures thereof. Exemplary hot melt adhesive include styrene-butadiene block copolymers; for example, as available under the trade designation KRATON from Kraton Corporation, Houston, Tex.
Thermoforming is a manufacturing process whereby the plastic film is heated to a pliable forming temperature, formed to a specific shape in a mold, and trimmed to create a usable product. The film is typically heated in an oven to a high-enough temperature that permits it to be stretched into or onto a mold and cooled to a finished shape. Its simplified version is vacuum forming. Suitable thermoforming techniques are well known to those of skill in the art. Protective films according to the present disclosure may be assessed for their thermoformability by thermoforming them in a mold (e.g., having right angle surfaces) and determining the amount of cracking of the cured composition from the edges of the molded shape to the center of the thermoformed shape. Preferred embodiments exhibit no cracking anywhere on the thermoformed shape. If the coating on the thermoformed shape cracks, the crack usually starts on the edge. For example, if a crack starts at the edge and continues 20% of the distance between the edge and the center of the thermoformed shape, then cracking is reported as 20% from the edge. Once a shape is thermoformed, typically there is no further cracking when that shape is used in further molding operations.
In a first embodiment, the present disclosure provides a composite film comprising:
a first unitary thermoplastic polymer film having first and second opposed major surfaces;
a low surface energy abrasion resistant layer disposed on the first major surface of the first unitary thermoplastic polymer film, wherein the low surface energy abrasion resistant layer comprises an at least partially cured curable composition, the curable composition comprising components:
a first adhesive layer proximate and securely bonded to the second major surface of the first unitary thermoplastic polymer film;
a second unitary thermoplastic polymer film proximate having two opposed major surfaces and securely bonded to the first adhesive layer; and
a second adhesive layer proximate and securely bonded to the second unitary thermoplastic polymer film opposite the first adhesive layer.
In a second embodiment, the present disclosure provides a composite film according to the first embodiment, further comprising a releasable liner releasably adhered to the second adhesive layer.
In a third embodiment, the present disclosure provides a composite film according to the first or second embodiment, wherein the first and second adhesive layers are pressure-sensitive adhesive layers.
In a fourth embodiment, the present disclosure provides a protective cover for an electronic device, the protective cover comprising:
a first unitary thermoplastic polymer film having first and second opposed major surfaces;
a low surface energy abrasion resistant layer disposed on the first major surface of the first unitary thermoplastic polymer film, wherein the low surface energy abrasion resistant layer comprises an at least partially cured curable composition, the curable composition comprising components:
a first adhesive layer proximate and securely bonded to the second major surface of the first unitary thermoplastic polymer film,
wherein the protective cover comprises a central planar section having first and second opposed major surfaces, wherein the central planar section is bounded by at least two linear side sections, wherein the at least two linear side sections extend out of plane from the central planar section to define inner and outer surfaces of the protective cover, and wherein the low surface energy abrasion resistant layer is disposed on the outer surface of the central planar section.
In a fifth embodiment, the present disclosure provides a cover for an electronic device according to the fourth embodiment, further comprising a releasable liner releasably adhered to the first adhesive layer.
In a sixth embodiment, the present disclosure provides a cover for an electronic device according to the fourth embodiment, further comprising:
a second unitary thermoplastic polymer film having two opposed major surfaces, the second unitary thermoplastic polymer film being proximate and securely bonded to the first adhesive layer; and
a second adhesive layer proximate and securely bonded to the second unitary thermoplastic polymer film opposite the first adhesive layer.
In a seventh embodiment, the present disclosure provides a cover for an electronic device according to the sixth embodiment, further comprising a releasable liner releasably adhered to the second adhesive layer.
In an eighth embodiment, the present disclosure provides a cover for an electronic device according to the sixth or seventh embodiment, wherein the first and second adhesive layers are pressure-sensitive adhesive layers.
In a ninth embodiment, the present disclosure provides a cover for an electronic device according to any one of the fourth to eighth embodiments, wherein if mounted to the electronic device the protective cover conforms to the surface of the electronic device.
In a tenth embodiment, the present disclosure provides a cover for an electronic device according to the ninth embodiment, wherein the protective cover has at least one opening therethrough to permit a user to access an operational control feature of the electronic device.
In an eleventh embodiment, the present disclosure provides a cover for an electronic device according to any one of the fourth to tenth embodiments, wherein the electronic device is a cell phone or a tablet computer.
In a twelfth embodiment, the present disclosure provides a cover for an electronic device according to any one of the fourth to eleventh embodiments, wherein the protective cover is thermoformed.
In a thirteenth embodiment, the present disclosure provides a cover for an electronic device according to any one of the fourth to twelfth embodiments, wherein the first and second unitary thermoplastic polymer films independently comprise polycarbonate or polyester.
In a fourteenth embodiment, the present disclosure provides a cover for an electronic device according to any one of the fourth to thirteenth embodiments, wherein the component d) is present in the curable composition.
In a fifteenth embodiment, the present disclosure provides a cover for an electronic device according to the fourteenth embodiment, wherein the component d) comprises a free-radical photoinitiator.
In a sixteenth embodiment, the present disclosure provides a cover for an electronic device according to any one of the fourth to fifteenth embodiments, wherein the component b) comprises at least one of 1,6-hexanediol di(meth)acrylate or an alkoxylated tetrahydrofurfuryl (meth)acrylate.
In a seventeenth embodiment, the present disclosure provides a cover for an electronic device according to any one of the fourth to sixteenth embodiments, wherein the component a) the urethane (meth)acrylate compound includes at least one of an isocyanurate ring or a biuret group.
In an eighteenth embodiment, the present disclosure provides a cover for an electronic device according to any one of the fourth to seventeenth embodiments, wherein the curable composition comprises alpha alumina particles having a Dv50 of from 0.1 to 1 micron.
In a nineteenth embodiment, the present disclosure provides a cover for an electronic device according to the eighteenth embodiment, wherein the alpha alumina particles have a Dv50 of from 0.2 to 0.3 micron.
In a twentieth embodiment, the present disclosure provides a cover for an electronic device according to the eighteenth or nineteenth embodiment, wherein the at least partially cured curable composition comprises from 0.2 to 3 weight percent of the alpha alumina particles.
In a twenty-first embodiment, the present disclosure provides a cover for an electronic device according to any one of the fourth to twentieth embodiments, wherein the at least partially cured curable composition comprises carbamylene groups. In a twenty-second embodiment, the present disclosure provides a cover for an electronic device according to any one of the fourth to twentieth embodiments, wherein the at least partially cured curable composition comprises a polyether.
In a twenty-third embodiment, the present disclosure provides a method of making a protective cover for an electronic device, the method comprising:
thermoforming a composite film to provide a protective cover comprising a central planar section having first and second opposed major surfaces, wherein the central planar section is bounded by at least two linear side sections, and wherein the composite film comprises:
a first unitary thermoplastic polymer film having first and second opposed major surfaces;
a low surface energy abrasion resistant layer disposed on the first major surface of the first unitary thermoplastic polymer film, wherein the low surface energy abrasion resistant layer comprises an at least partially cured curable composition, the curable composition comprising components:
a first adhesive layer proximate and securely bonded to the second major surface of the first unitary thermoplastic polymer film,
wherein the at least two linear side sections extend out of plane from the central planar section to define inner and outer surfaces of the protective cover, and wherein the low surface energy abrasion resistant layer is disposed on at least a portion of the outer surface.
In a twenty-fourth embodiment, the present disclosure provides a method according to the twenty-third embodiment, wherein the composite film further comprises a releasable liner releasably adhered to first adhesive layer.
In a twenty-fifth embodiment, the present disclosure provides a method according to the twenty-third embodiment, wherein the composite film further comprises:
a second unitary thermoplastic polymer film having two opposed major surfaces, the second unitary thermoplastic polymer film being proximate and securely bonded to the first adhesive layer; and
a second adhesive layer proximate and securely bonded to the second unitary thermoplastic polymer film opposite the first adhesive layer.
In a twenty-sixth embodiment, the present disclosure provides a method according to the twenty-fifth embodiments, wherein the composite film further comprises a releasable liner releasably adhered to the second adhesive layer.
In a twenty-seventh embodiment, the present disclosure provides a method according to the twenty-fifth or twenty-sixth embodiment, wherein the first and second adhesive layers are pressure-sensitive adhesive layers.
In a twenty-eighth embodiment, the present disclosure provides a method according to any one of the twenty-third to twenty-seventh embodiments, wherein if mounted to the electronic device the protective cover conforms to the surface of the electronic device.
In a twenty-ninth embodiment, the present disclosure provides a method according to the twenty-eighth embodiment, wherein the protective cover has at least one opening therethrough to permit a user to access an operational control feature of the electronic device.
In a thirtieth embodiment, the present disclosure provides a method according to the twenty-ninth embodiment, wherein the electronic device is a cell phone or a tablet computer.
In a thirty-first embodiment, the present disclosure provides a method according to any one of the twenty-third to thirtieth embodiments, wherein the first and second unitary thermoplastic polymer films independently comprise polycarbonate or polyester.
In a thirty-second embodiment, the present disclosure provides a method according to any one of the twenty-third to thirty-first embodiments, wherein the component d) is present in the curable composition.
In a thirty-third embodiment, the present disclosure provides a method according to the thirty-second embodiment, wherein the component d) comprises a free-radical photoinitiator.
In a thirty-fourth embodiment, the present disclosure provides a method according to any one of the twenty-third to thirty-third embodiments, wherein the component b) comprises at least one of 1,6-hexanediol di(meth)acrylate or an alkoxylated tetrahydrofurfuryl (meth)acrylate.
In a thirty-fifth embodiment, the present disclosure provides a method according to any one of the twenty-third to thirty-fourth embodiments, wherein in the component a) the urethane (meth)acrylate compound includes at least one of an isocyanurate ring or a biuret group.
In a thirty-sixth embodiment, the present disclosure provides a method according to any one of the twenty-third to thirty-fifth embodiments, wherein the curable composition comprises alpha alumina particles having a Dv50 of from 0.1 to 1 micron.
In a thirty-seventh embodiment, the present disclosure provides a method according to the thirty-sixth embodiment, wherein the alpha alumina particles have a Dv50 of from 0.2 to 0.3 micron.
In a thirty-eighth embodiment, the present disclosure provides a method according to any one of the thirty-sixth or thirty-seventh embodiment, wherein the at least partially cured curable composition comprises from 0.15 to 9 weight percent of the alpha alumina particles.
In a thirty-ninth embodiment, the present disclosure provides a method according to any one of the twenty-third to thirty-eighth embodiments, wherein the at least partially cured curable composition comprises carbamylene groups.
In a fortieth embodiment, the present disclosure provides a method according to any one of the twenty-third to thirty-ninth embodiments, wherein the at least partially cured curable composition comprises a polyether.
Objects and advantages of this disclosure are further illustrated by the following non-limiting 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 disclosure.
Unless otherwise noted, all parts, percentages, ratios, etc. in the Examples and the rest of the specification are by weight.
Abrasion of film samples was tested downweb to the coating direction using a Taber model 5750 Linear Abraser (Taber Industries, North Tonawanda, N.Y.). The film samples tested were not thermoformed. The collet oscillated at 40 cycles/minute and the length of stroke was 2 inches (5.08 cm). The abrasive material used for this test was an eraser insert (obtained from Summers Optical, a division of EMS Acquisition Corp., Hatfield, Pa.). The eraser insert had a diameter of 6.5 mm and met the requirements of military standard Mil-E-12397B.
The eraser insert was held in place through duration of test by the collet. One sample was tested on three different spots for each example with a weight of 1.1 kg weight and 20 cycles. After abrasion, the sample was cleaned by wiping with a lens cleaning towelette (Radnor Products, Radnor, Pa.). The optical haze and transmission of each sample was measured using a Haze-Gard Plus haze meter (BYK Gardner, Columbia, Md.) at the three different spots. The reported values of haze and transmission are the average of the values obtained on the three different spots. The delta haze value for each sample was calculated by subtracting the haze of an untested region of the sample. The loss of transmission for each sample was calculated by subtracting the transmission after testing from the transmission of an untested region of the sample.
The steel wool abrasion test was performed on a Taber model 5750 Linear Abraser (Taber Industries, North Tonawanda, N.Y.). The collet oscillated at 60 cycles/minute and the length of stroke is 4 inches. The abrasive material used for this test was a steel wool pad (Grade #0000, 2 cm×2 cm square). The steel wool pad was held in place through duration of test by the collet. One sample was tested for each example with a weight of 1.0 kg weight and 500 cycles. After abrasion, the sample was cleaned by wiping with a lens cleaning towelette (Radnor Products, Radnor, Pa.). The optical haze and transmission of each sample was measured using a Haze-Gard Plus haze meter (BYK Gardner, Columbia, Md.) at three different points along the abraded area. The reported values of haze and transmission are the average of the values obtained on the three different spots. The delta haze value for each sample was calculated by subtracting the haze of an untested region of the sample. The loss of transmission for each sample was calculated by subtracting the transmission after testing from the transmission of an untested region of the sample.
The alpha alumina nanoparticle dispersions were made through a media milling process. MEK (280 grams), 86 grams of BYK-W 9010 dispersing additive (BYK USA, Wallingford, Conn.), and 418 grams of ultrapure alpha alumina NP were mixed together using a Dispermat CN-10 laboratory high-shear disperser (BYK-Gardner USA, Columbia, Md.). The mixed dispersion was milled in MiniCer laboratory media mill (Netzsch, Exton, Pa.) with 0.2 mm yttria stabilized zirconia milling media. Aliquots (40 grams) were sampled at 10, 20, 30 and 90 min. The solid content of the samples collected at 10, 20, 30 and 90 min was 59.6 weight percent, 60.1 weight percent, 61.1 weight percent and 53.6 weight percent, respectively. 0.2 mL of alpha alumina NP was diluted with 2 mL of MEK prior to particle size analysis by laser diffraction, which was performed on Horiba LA-960. Dv10 means a cumulative 10% point of diameter (or 10% pass particle size). Dv50 means a cumulative 50% point of diameter (or 50% pass particle size), also refer to median diameter. Dv90 means a cumulative 90% point of diameter. The volume average Dv10, Dv50 and Dv90 values (in micrometers, μm) for each filled resin are shown in Table 2, below.
Thermoforming on lens mold was performed using a MAAC sheet feed vacuum thermoforming system (MAAC machinery Corp., Carol Stream, Ill.). The thermoforming system clamped the coated film sheet to be thermoformed, and the sheet was shuttled between top and bottom heating elements to heat the sheet to a temperature of 340° F. (171° C.) to 380° F. (193° C.). The heated sheet was then shuttled over the top of a forming tool with the 8 base lens geometry (length of the mold cavity was 8 mm and the width was 65 mm). The tool was heated to a temperature of 150° F. (66° C.) to 250° F. (121° C.). Then, the tool was raised into the sheet and vacuum was pulled to force the heated sheet to form to the 8 base lens tool geometry.
Hardcoats on thermoplastic films were assessed for their thermoformability, by thermoforming them into a lens shape and determining the amount of cracking of the hardcoat from the edges of the lens shape to the center of the lens shape. The most preferred embodiments exhibit no cracking anywhere on the lens shape. If the coating on the lens shape cracked, the crack usually started on the edge. The percent crack from the edge was measured from the edge of the lens to the center of the lens. For example, if a crack started at the edge and continued 20% of the distance between the edge and the center of the lens shape, then cracking was reported as 20% from the edge. If cracks were present half way between the edge and the center, the crack level was recorded as 50% crack up from the edge. The percentage location was measured visually with an un-aided eye.
Rating Scale for the Amount of Cracks
Thermoforming on a one-millimeter edge aluminum phone mold was performed on a Hytech AccuForm IL50 thermoforming apparatus. The mold had a generic phone shape, with 1 mm radii on four edges. The four corners of the top surface where the films are formed have radii of 0.1 in (2.54 mm), 0.15 in (3.81 mm), 0.25 in (6.35 mm), and 0.5 in (12.7 m), respectively. The thermoforming conditions include heated platen temperature of 350° F. (177° C.), mold temperature of 80° F. (27° C.), preheat time of 6 seconds, preheat pressure of 60 psi and form time of 6 seconds.
The thermoformed samples were rated as “no cracks”, “cracks at edge only” and “cracks across surface”. “Cracks at the edge only” means cracking developed around the bottom of the sample where the bottom of the mold touches the mold platform of the molding machine. It does not necessary mean the cracks were on the actual usable part of the thermoformed samples.
Static water contact angle was measured on KRUSS Drop Shape Analyzer DSA100, Kruss Gmbh, Hamburg, Germany. Water (5 microliters) was transferred onto the surface, and the static water contact angle was obtained through analyzing the image. Three measurements were performed on different locations on the surface and the average value and standard deviation were calculated.
Crosshatch adhesion of each sample was measured using the ASTM D3359-09, “Standard Test Methods for Measuring Adhesion by Tape Test”, Test Method B using 3M 893 filament tape (3M Company, St. Paul, Minn.).
A 250-mL jar equipped with a magnetic stir bar was charged with 39.76 g (0.2082 eq.) of DESN100, 25 g of MEK, 12.33 g (0.1062 eq.) of HEA, 47.91 g (0.1062 eq.) of PETA, for a total of 1.01 eq. OH per eq. of NCO, 0.025 g (250 ppm) BHT, 0.005 g (50 ppm) of 4-hydroxy TEMPO, and 0.05 g (500 ppm) of DBTDL. The jar was placed in a water bath at room temperature and allowed to stir for 10 min. After 10 min., it was placed into a 55° C. bath for 4 hr. At the end of that time, the reaction mixture was monitored by FTIR and found to have no NCO peak at 2265 cm−1. The resulting material was 80 weight percent solids.
PE2-PE14 were prepared in the same manner as PE1 described above by reacting the preparations reported in Table 3. The reactions were carried out using an appropriately sized jar. The amount of materials used in preparations described in Table 3 were reported in grams (g), and, unless noted otherwise, further included 250 ppm BHT, 50 ppm 4-hydroxy TEMPO, and 500 ppm DBTDL with respect to solids. The resulting products were 80 weight percent solids in MEK.
The average (meth)acrylate functionality is calculated in the following fashion. The functionality of the added acrylates for each compound is first calculated. For instance, the PE3 below is designated as 1.0 DESN100+0.25 HEA+0.75 PETA. This means that the compound is the reaction product of 1 equivalent of isocyanate groups (as DESN100) and 0.25 hydroxyl equivalents of hydroxyethyl acrylate and 0.75 hydroxyl equivalents of PETA. The HEA has one acrylate group per hydroxyl group and the PETA has 3 acrylate groups per hydroxyl group. The functionality of added acrylates for this compound is then (0.25×1)+(0.75×3)=2.5. The average (meth)acrylate functionality is found by multiplying the functionality of the added acrylates for each compound by the average functionality of the polyisocyanate. According to Covestro, the average functionality for DESN100 is 3.6, so the average (meth)acrylate functionality for the compound is at 2.5×3.6=9.
By this method, average functionality of polyisocyanates for DESN3300, DESN3800, and DESZ4470BA are 3.5, 3.0, and 3.3, respectively.
Coating solutions were prepared by mixing components as reported in Table 4. Then, to prepare each preparative example, the indicated coating solution composition in Table 4 was coated at 32 weight percent solids onto PC film. In Table 5, the identity of the Preparative Example Oligomer is reported for each Preparative Hard Coated Film. The coating was done using a No. 7 wire-wound rod (available from RD Specialties, Webster, N.Y., nominal wet film thickness 0.63 mils (16.0 microns)) and dried at 80° C. for 1.5 min. The dried coating was then cured using a UV processor equipped with an H-type bulb (500 W, available from Heraeus Noblelight America/Fusion UV Systems, Gaithersburg, Md.) at 100% power under nitrogen at 30 feet/minute (12.1 m/min). The cured coating had an estimated thickness of about 3.4 microns.
Thermoforming of Preparative Examples PE9-PE16 to generate thermoformed CPEX9-CPEX16 was performed using a MAAC sheet feed vacuum thermoforming system (MAAC Machinery Corp., Carol Stream, Ill.). The thermoforming system clamped the coated film sheet to be thermoformed, and the sheet was shuttled between top and bottom heating elements to heat the sheet to a temperature of 340° F. (171° C.) to 380° F. (193° C.). The heated sheet was then shuttled over the top of a forming tool with the 8 base lens geometry (length of the mold cavity was 8 mm and the width was 65 mm). The tool was heated to a temperature of 150° F. (66° C.) to 250° F. (121° C.). Then, the tool was raised into the sheet and vacuum was pulled to force the heated sheet to form to the 8 base lens tool geometry.
Test results for films used for thermoforming are reported in Table 6, below.
Thermoforming results are reported in Table 7, below.
Formulation A1 was made by adding 0.64 g of photoinitiator ESACURE ONE and 0.32 g of TEG2100 to 34.80 g of PE1 (80 wt. % of MEK), followed by dilution with 48 g of ethanol and 6.0 g of 1-methoxy-2-propanol. The resulting Formulation A1 had 32.1 wt. % solids.
Formulation A1 was used to make coating formulations in Table 8. HDDA and SR217 in Table 8 were diluted to 32 wt. % solids in ethanol. Tego Rad additives (TEG2500 and TEG2700) were diluted to 10 wt. % solids in ethanol prior to use. PE25-PE31 were made by mixing different amounts of prepared solutions of ingredients at room temperature. The formulations were hand-coated on 5 mil PC substrate using a #12 wire-wound rod (RD Specialties, Webster, N.Y., nominal wet film thickness 1.08 mils (27.4 microns)). The coated PC films were allowed to dry at room temperature first and then dried at 80° C. in an oven for 1 min. The dried samples were cured using a UV processor equipped with an H-type bulb (500 W, Heraeus Noblelight America/Fusion UV Systems), Gaithersburg, Md.) at 100% power under nitrogen purge at 30 feet/min (12.1 m/min). Coatings made from PE30 and PE31 had an uneven surface.
The coating formulations and resulted coated articles were reported in Table 9. The haze and transmission before and after eraser abrasion tests were measured and results are reported in Table 10. The thermoforming on lens mold and crosshatch results are reported in Table 11.
Formulation A1 was used in making the formulations shown in Table 12. The SR611 used in Table 12 was diluted to 32 wt. % solids in ethanol. TEG2500 was diluted to 10 wt. % solids in ethanol. The formulations were made by mixing different amounts of prepared solutions of ingredients at room temperature. The formulations were hand-coated on 5-mil (0.127 mm) PC substrate using a #12 wire-wound rod (nominal wet film thickness 1.08 mils (27.4 microns)). The coated PC films were allowed to dry at room temperature first and then dried at 80° C. in an oven for 1 min. The dried samples were cured using a UV processor equipped with an H-type bulb (500 W, Heraeus Noblelight America/Fusion UV Systems, Gaithersburg, Md.) at 100% power under nitrogen purge at 30 feet/min (12.1 m/min).
The formulations and resultant coated articles are reported in Table 13. The haze and transmission before and after eraser abrasion tests were measured and results are reported in Table 14. The thermoforming on lens mold and crosshatch results are reported in Table 15.
To compare the effects of coating thickness on A Haze and A Transmission, PE40 was coated on 5 mil PC films using #12, #9, and #7 wire-wound rods (RD Specialties, nominal wet film thicknesses of 1.08 mils (27.4 microns), 0.81 mil (20.57 microns), and 0.62 mil (16.00 microns), respectively), and the resulting coated PC films were named as PE 53, PE54 and PE55, respectively. Each coating thickness had 5 replicates. The coated PC films were allowed to dry at room temperature first and then dried at 80° C. in an oven for 1 min. The dried samples were cured using a UV processor equipped with an H-type bulb (500 W, Heraeus Noblelight America/Fusion UV Systems, Gaithersburg, Md.) at 100% power under nitrogen purge at 30 feet/min (12.1 m/min). The haze and transmission of cured hardcoats were measured after eraser abrasion test (Table 16). After thermoforming on lens mold, all hardcoated PC films had no or only slight edge cracking (2 replicates using a #12 wire-wound rod had an area of very slight and few lines that went up about 20-30% from the edge).
Formulation B was made by adding 0.64 g of photoinitiator Esacure One to 34.80 g of PE1 (80 wt. % of MEK), followed by dilution with 54 g of MEK. The resulting Formulation B had 32.1 wt. % solids.
Formulation B was used in making the formulations shown in Table 17. The SR611 solution used in Table 17 had 32 wt. % solids in MEK. The TEGO Rad additives (TEG2100, TEG2250, TEG2500) were diluted to 10 wt. % solids in MEK. The fluoro additives (HFPO-Urethane and —C4F9-acrylate) had 30 wt. % solids in MEK. The formulations were made by mixing different amounts of prepared solutions of ingredients at room temperature. The formulations were hand-coated on 2 mil PET substrates using a #12 wire-wound rod (RD Specialties, nominal wet film thickness 1.08 mils (27.4 microns)). The coated PET films were allowed to dry at room temperature first and then dried at 90° C. in an oven for 1 min. The dried samples were cured using a UV processor equipped with an H-type bulb (500 W, Heraeus Noblelight America/Fusion UV Systems, Gaithersburg, Md.) at 100% power under nitrogen purge at 30 feet/min (12.1 m/min).
The formulations and resulted coated articles are reported in Table 18. The haze and transmission before and after eraser abrasion tests as well as static water contact angle were measured and results are reported in Table 19. Six replicates of PE61 were thermoformed on 1 mm edge aluminum phone mold following the described procedure. Cracks were observed at the edge only. PE56, PE57 and PE60 were thermoformed on 1 mm edge aluminum phone mold following the described procedure and cracks were observed at the edge only.
Formulation A2 was made by adding 0.64 g of photoinitiator ESACURE ONE and 0.32 g of TEG2100 to 34.80 g of PE1 (80 wt. % of MEK), followed by dilution with 54.0 g of MEK. The resulting Formulation A2 had 32.1 wt. % solids.
Formulation A2 was used in making the formulations shown in Table 20. The SR611 used in Table 20 was diluted to 32 wt. % solids in MEK. The HFPO-Urethane had 30 wt. % solids in MEK. The formulations were made by mixing different amounts of prepared solutions of ingredients at room temperature. The formulations were hand-coated on 2 mil PET substrates using a #12 wire-wound rod (RD Specialties, nominal wet film thickness 1.08 mils (27.4 microns)). The coated PET films were allowed to dry at room temperature first and then dried at 90° C. in an oven for 1 min. The dried samples were cured using a UV processor equipped with an H-type bulb (500 W, Heraeus Noblelight America/Fusion UV Systems, Gaithersburg, Md.) at 100% power under nitrogen purge at 30 feet/min (12.1 m/min).
The formulations and resulted coated articles are reported in Table 21. The haze and transmission before and after steel wool abrasion tests as well as static water contact angle values were measured and results are reported in Table 22.
Formulation A2 was used in making the formulations shown in Table 23. The SR611 and HDDA used in Table 23 were diluted to 32 wt. % solids in MEK. The TEG2100 were diluted to 10 wt. % solids in MEK. PE78 and PE79 were made by mixing different amounts of prepared solutions of ingredients at room temperature. The formulations were hand-coated on 2 mil PET substrates using a #12 wire-wound rod (RD Specialties, nominal wet film thickness 1.08 mils (27.4 microns)). The coated PET films were allowed to dry at room temperature first and then dried at 90° C. in an oven for 1 min. The dried samples were cured using a UV processor equipped with an H-type bulb (500 W, Heraeus Noblelight America/Fusion UV Systems, Gaithersburg, Md.) at 100% power under nitrogen purge at 30 feet/min (12.1 m/min). The PET films coated with PE78 and PE79 were labeled as PE80 and PE81.
PE80 and PE81 were thermoformed on 1 mm edge aluminum phone mold following the described procedure and cracks were observed at the edge only.
Formulation C and Formulation D were made by mixing the listed ingredients in Table 24 and Table 25 at room temperature, respectively. The formulations were hand-coated on 2 mil PET substrates using #12 wire-wound rod (RD Specialties, nominal wet film thickness 1.08 mils (27.4 microns)). The coated PET films were allowed to dry at room temperature first and then dried at 80° C. in an oven for 1 min. The dried samples were cured using a UV processor equipped with an H-type bulb (500 W, Heraeus Noblelight America/Fusion UV Systems, Gaithersburg, Md.) at 100% power under nitrogen purge at 30 feet/min (12.1 m/min).
Formulation C, D, and A2 were coated on PET films and the resulting coated articles were labeled as PE82, PE83 and PE84, respectively (Table 26). The haze and transmission before and after eraser abrasion tests are reported in Table 27.
Formulation A1 was used to make coating formulations in Table 28. In Table 28, SR611 was diluted to 32 wt. % solids in ethanol. Formulations in Table 28 were made by mixing the indicated amounts of ingredients at room temperature. The formulations were hand-coated on PC film using a #12 wire-wound rod (RD Specialties, nominal wet film thickness 1.08 mils (27.4 microns)). The coated PC films were allowed to dry at room temperature first and then dried at 80° C. in an oven for 1 min. The dried samples were cured using a UV processor equipped with an H-type bulb (500 W, Heraeus Noblelight America/Fusion UV Systems, Gaithersburg, Md.) at 100% power under nitrogen purge at 30 feet/min (12.1 m/min).
The results of thermoforming of hardcoated PC films on lens mold following a described procedure are also reported in Table 29. Haze and transmission before and after eraser abrasion tests were measured on hardcoated PC films and results are reported in Table 30.
Formulation A1 was used to make coating formulations in Table 31. SR611 in Table 31 was diluted to 32 wt. % solids in ethanol.
PE96-PE100, PE101-PE104 were prepared using 30 min milled alpha alumina nanoparticle dispersion with a concentration of 61.1 wt. % solids in MEK. PE105, PE106 and PE107 were prepared using 10 min, 20 min, and 90 min milled alpha alumina nanoparticle dispersions, respectively. Alpha alumina nanoparticle dispersions used in PE105, PE106 and PE107 were 59.6 wt. %, 60.1 wt. % and 53.6 wt. % solids in MEK, respectively. PE95-PE107 were made by mixing different amounts of prepared solutions of ingredients at room temperature. The formulations were hand-coated on PC film using a #12 wire-wound rod (RD Specialties, nominal wet film thickness 1.08 mils (27.4 microns)). The coated PC films were allowed to dry at room temperature first and then dried at 80° C. in an oven for 1 min. The dried samples were cured using a UV processor equipped with an H-type bulb (500 W, Heraeus Noblelight America/Fusion UV Systems, Gaithersburg, Md.) at 100% power under nitrogen purge at 30 feet/min (12.1 m/min).
The results of thermoforming of hardcoated PC films on lens mold following a described procedure are reported in Table 32. The haze and transmission of the hardcoated PC films before and after eraser abrasion tests were measured and results are reported in Table 33.
Formulation E was made by adding 0.64 g of photoinitiator ESACURE ONE to 34.80 g of PE1 (80 wt. % of MEK), followed by dilution with 48 g of ethanol and 6.0 g of 1-methoxy-2-propanol. The resulting Formulation E was 31.8 wt. % solids.
Formulation E was used to make coating formulations in Table 34. SR611 in Table 34 was diluted to 32 wt. % solids in ethanol. Alpha alumina nanoparticles (30 min milled) used in Table 34 were used at a concentration of 61.1 wt. % solids in MEK. PE121-PE127 were made by mixing different amounts of prepared solutions of ingredients shown in Table 34 at room temperature. The formulations were hand-coated on PC film using a #12 wire-wound rod (RD Specialties, nominal wet film thickness 1.08 mils (27.4 microns)). The coated PC films were allowed to dry at room temperature first, and then dried at 90° C. in an oven for 1 min. The dried samples were cured using a UV processor equipped with an H-type bulb (500 W, Heraeus Noblelight America/Fusion UV Systems, Gaithersburg, Md.) at 100% power under nitrogen purge at 30 feet/min (12.1 m/min).
The results of thermoforming of the hardcoated PC films on lens mold following a described procedure are reported in Table 35. The haze and transmission of the hardcoated PC films before and after eraser abrasion tests were measured and results are reported in Table 36.
To make PE135-PE139, a master Formulation B was first prepared by adding 0.64 g of photoinitiator ESACURE ONE to 34.80 g of urethane acrylate PE1 (80 wt. % of MEK), followed by dilution with 54.0 g of MEK. The resulting Formulation C has 31.8 wt. % of solid.
Formulation B was used to make coating formulations in Table 37. SR611 in Table 37 was diluted to 32 wt. % solids in MEK. Alpha alumina nanoparticle dispersion was used at a concentration of 61.1 wt. % solids in MEK, which was prepared by milling commercially available alpha alumina particles following a described procedure. PE135-PE139 were made by mixing different amounts of prepared solutions of ingredients shown in Table 37 at room temperature. The formulations were hand-coated on PET film using a #12 wire-wound rod (RD Specialties, nominal wet film thickness 1.08 mils (27.4 microns)). The coated PET film were allowed to dry at room temperature first and then dried at 90° C. in an oven for 1 min. The dried samples were cured using a UV processor equipped with an H-type bulb (500 W, Heraeus Noblelight America/Fusion UV Systems, Gaithersburg, Md.) at 100% power under nitrogen purge at 50 feet/min (15.2 m/min). The formulations and resulted hardcoated PET films are reported in Table 38. The eraser abrasion test was performed and results are reported in Table 39.
Alpha alumina nanoparticles were added to crosslinked polyurethane coatings. Alpha alumina nanoparticle dispersion was used at a concentration of 61.1 wt. % solids in MEK, which was prepared by milling commercially available alpha alumina particles following a described procedure. PE145-PE147 were made by mixing different amounts of prepared solutions of ingredients shown in Table 40 at room temperature. The formulations were hand-coated on PET film using a #12 wire-wound rod (RD Specialties, nominal wet film thickness 1.08 mils (27.4 microns)). After drying at room temperature, the coated samples were cured in an oven at 80° C. for 30 min. The formulations and resulted hardcoated PET films are reported in Table 41. The haze and transmission of the hardcoated PET films before and after eraser abrasion tests were measured and results are reported in Table 42.
Alpha alumina nanoparticles were added to crosslinked epoxy coatings. Alpha alumina nanoparticle dispersion was used at a concentration of 61.1 wt. % solids in MEK, which was prepared by milling commercially available alpha alumina particles following a described procedure. PE151-PE156 were made by mixing different amounts of prepared solutions of ingredients shown in Table 43 at room temperature. The formulations were hand-coated on PET film using a #12 wire-wound rod (RD Specialties, Webster, N.Y., nominal wet film thickness 1.08 mils (27.4 microns)). The samples were first dried in air at room temperature and then cured using a UV processor equipped with a D-type bulb (Heraeus Noblelight America/Fusion UV Systems, Gaithersburg, Md.) at 100% power under nitrogen purge at 30 feet/min (12.1 m/min). The UV cured samples were further cured in an oven at 100° C. for 30 min.
The formulations and resulted hardcoated PET films are reported in Table 44. The haze and transmission before and after eraser abrasion tests were measured and results are reported in Table 45.
The optically clear adhesive used in making the multilayer articles containing hardcoats was prepared as follows. 80 g of 2-ethylhexyl acrylate (Sigma-Aldrich, St. Louis, Mo.), 10 g of 2ethylhexyl methacrylate (Sigma-Aldrich), 4 g of hydroxyethyl acrylate (Kowa America, New York, N.Y.), 6 g of acrylamide (Zibo Xinye Chemical, Zibo City, China), 0.15 g of thermal initiator Vazo52 (Dupont, Wilmington, Del.), 0.08 g of Karenz MT PE1 (Showa Denko America, New York, N.Y.), and 60 g of MEK were charged to a reactor vessel. This vessel was sparged with nitrogen for 5 minutes, sealed, and then placed in an agitated water bath at 60° C. for 20 hours. The generated solution polymer was then cooled, sparged with air for 10 minutes, and 0.3 g of isocyanatoethyl methacrylate (Showa Denko America) was added to the vessel. The vessel was again sealed and heated to 50° C. for 12 hours to allow for the IEM to react with pendant OH functionality on the formed acrylic polymer. Following this functionalization, 0.4 g of Irgacure 184 (BASF, Florham Park, N.J.), 1 g of SR351 (Sartomer Co, Exton, Pa.), 25 grams of 2-methoxypropanol (Alfa Aesar, Ward Hill, Mass.), and 3.3 grams of methanol were added to the vessel and mixed for 1 hour.
The adhesive was applied on PET film using a notched bar coater with the slot size set between size 0.003 in and 0.004 in (0.08 mm-0.10 mm) followed by baking in an oven for 10 min at 70° C. The resulting adhesive coated PET film was used in making the multilayer articles along with the hardcoated PET film. The thickness of the adhesive on PET film was determined as 135.7±1.5 μm using a digital thickness gauge after photo curing of the multilayer article.
Four different hardcoats were applied on PET film for making the multilayer articles.
Formulation B was used to make coating formulations in Table 46. SR611 in Table 46 was diluted to 32 wt. % solids in MEK. Alpha alumina nanoparticle dispersion was used at a concentration of 61.1 wt. % solids in MEK, which was prepared by milling commercially available alpha alumina particles following a described procedure. PE139 and PE163 were made by mixing different amounts of prepared solutions of ingredients shown in Table 46 at room temperature. The formulations were hand-coated on PET film using a #12 wire-wound rod (RD Specialties, nominal wet film thickness 1.08 mils (27.4 microns)). The coated PET films were allowed to dry at room temperature first and then dried at 90° C. in an oven for 1 min. The dried samples were cured using a UV processor equipped with an H-type bulb (500 W, Heraeus Noblelight America/Fusion UV Systems, Gaithersburg, Md.) at 100% power under nitrogen purge at 50 feet/min (15.2 m/min). The formulations and resulted hardcoated PET films as well as eraser abrasion test results are reported in Table 47.
Formulation F was first prepared by adding 0.32 g of photoinitiator ESACURE ONE to 17.40 g of the mixture of PE2 (80 wt. % of MEK) and 0.16 g of Tegorad 2100, followed by dilution with 27 g of MEK. The resulting Formulation D has 32.1 wt. % of solids.
Formulation F was used to make PE165 in combination with other listed ingredients in Table 48. SR611 was diluted to 32 wt. % solids in MEK. Tegorad 2100 was diluted to 10 wt. % solids in MEK and HFPO-Urethane had 30 wt. % solids in MEK. PE165 was prepared at room temperature and hand-coated on PET film using a #12 wire-wound rod (RD Specialties, nominal wet film thickness 1.08 mils (27.4 microns)). The coated PET films were allowed to dry at room temperature first and then dried at 90° C. in an oven for 1 min. The dried samples were cured using a UV processor equipped with an H-type bulb (500 W, Heraeus Noblelight America/Fusion UV Systems, Gaithersburg, Md.) at 100% power under nitrogen purge at 50 feet/min (15.2 m/min). The PET film coated with PE165 is labeled as PE166. The eraser abrasion test was performed following the described procedure and results are reported in Table 49.
Formulation G was prepared by adding 0.32 g of photoinitiator ESACURE ONE to the mixture of 17.40 g of PE3 (80 wt. % of MEK) and 0.16 g of Tegorad 2100, followed by dilution with 27 g of MEK. The resulting Formulation G has 32.1 wt. % of solid.
Formulation G was used to make PE167 in combination with other listed ingredients in Table 50. SR611 was diluted to 32 wt. % solids in MEK. Tegorad 2100 was diluted to 10 wt. % solids in MEK and HFPO-Urethane had 30 wt. % solids in MEK. PE167 was prepared at room temperature and hand-coated on PET film using a #12 wire-wound rod (RD Specialties, nominal wet film thickness 1.08 mils (27.4 microns)). The coated PET films were allowed to dry at room temperature first and then dried at 90° C. in an oven for 1 min. The dried samples were cured using a UV processor equipped with an H-type bulb (500 W, Heraeus Noblelight America/Fusion UV Systems, Gaithersburg, Md.) at 100% power under nitrogen purge at 50 feet/min (15.2 m/min). The PET film coated with PE167 is labeled as PE168. The eraser abrasion test was performed following the described procedure and results are reported in Table 51.
To make PE171, Formulation H was first prepared by adding 0.32 g of photoinitiator ESACURE ONE to the mixture of 17.40 g of PE169 (80 wt. % of MEK) and 0.16 g of Tegorad 2100, followed by dilution with 27 g of MEK. The resulting Formulation H has 32.1 wt. % of solid.
Formulation H was used to make PE171 in combination with other listed ingredients in Table 53. SR611 was diluted to 32 wt. % solids in MEK. Tegorad 2100 was diluted to 10 wt. % solids in MEK and HFPO-Urethane had 30 wt. % solids in MEK. PE171 was prepared at room temperature and hand-coated on PET film using a #12 wire-wound rod (RD Specialties, nominal wet film thickness 1.08 mils (27.4 microns)). The coated PET films were allowed to dry at room temperature first and then dried at 90° C. in an oven for 1 min. The dried samples were cured using a UV processor equipped with an H-type bulb (500 W, Heraeus Noblelight America/Fusion UV Systems, Gaithersburg, Md.) at 100% power under nitrogen purge at 50 feet/min (15.2 m/min). The PET film coated with PE171 is labeled as PE172. The eraser abrasion test was performed following the described procedure and results are reported in Table 54.
Formulation I was prepared by adding 0.32 g of photoinitiator ESACURE ONE to the mixture of 17.40 g of PE170 (80 wt. % of MEK) and 0.16 g of Tegorad 2100, followed by dilution with 27 g of MEK. The resulting Formulation I has 32.1 wt. % of solid.
Formulation I was used to make PE173 in combination with other listed ingredients in Table 55. SR611 was diluted to 32 wt. % solids in MEK. Tegorad 2100 was diluted to 10 wt. % solids in MEK and HFPO-Urethane had 30 wt. % solids in MEK. PE173 was prepared at room temperature and hand-coated on PET film using a #12 wire-wound rod (RD Specialties, nominal wet film thickness 1.08 mils (27.4 microns)). The coated PET films were allowed to dry at room temperature first and then dried at 90° C. in an oven for 1 min. The dried samples were cured using a UV processor equipped with an H-type bulb (500 W, Heraeus Noblelight America/Fusion UV Systems, Gaithersburg, Md.) at 100% power under nitrogen purge at 50 feet/min (15.2 m/min). The PET film coated with PE173 is labeled as PE174. The eraser abrasion test was performed following the described procedure and results are reported in Table 56.
Formulation A2 was used to make PE175 in combination with other listed ingredients in Table 57. SR611 was diluted to 32 wt. % solids in MEK. Tegorad 2100 was diluted to 10 wt. % solids in MEK and HFPO-Urethane had 30 wt. % solids in MEK. PE175 was prepared at room temperature and hand-coated on PET film using a #12 wire-wound rod (RD Specialties, nominal wet film thickness 1.08 mils (27.4 microns)). The coated PET films were allowed to dry at room temperature first and then dried at 90° C. in an oven for 1 min. The dried samples were cured using a UV processor equipped with an H-type bulb (500 W, Heraeus Noblelight America/Fusion UV Systems, Gaithersburg, Md.) at 100% power under nitrogen purge at 50 feet/min (15.2 m/min). The PET film coated with PE175 is labeled as PE176. The eraser abrasion test was performed following the described procedure and results are reported in Table 58.
Two different multilayer articles, Construction 1 and Construction 2, were laminated by hand using the hardcoated PET film (PE144, PE164, PE166 and PE168), adhesive coated PET film and a release liner. Construction 1 had four layers of materials from the top surface to the bottom, namely hardcoat, PET film, adhesive and release liner. Construction 2 had six layers of materials from the top surface to the bottom, namely hardcoat, PET film, adhesive, PET film, adhesive and release liner.
To make construction 1, the release liner was coated with adhesive using a notched bar coater with the slot size set between 0.003 in and 0.004 in (0.08 mm-0.10 mm) followed by baking in an oven for 10 min at 70° C. The PET side of the hardcoated PET film was laminated onto the adhesive coated release liner using a rubber hand roller. Air bubble and defects were carefully avoided by applying tension on the hardcoated PET film during lamination. The adhesive of laminated articles was cured with 2 passes using a UV processor equipped with a D-type bulb (600 W, Heraeus Noblelight America/Fusion UV Systems, Gaithersburg, Md.) at 50% power in air at 15 feet/min (4.6 m/min). The curing was performed through the release liner.
To make construction 2, the adhesive was first coated on PET film using a notched bar coater with the slot size set between 0.003 in and 0.004 in (0.08 mm-0.10 mm) followed by baking in an oven for 10 min at 70° C. The PET side of the hardcoated PET film was laminated onto the adhesive coated PET film. Air bubble and defects were carefully avoided by applying tension on the hardcoated PET film during lamination. This results in an intermediate article hardcoat/PET/adhesive/PET. The release liner was coated with adhesive using a notched bar coater with the slot size set between 0.003 in and 0.004 in (0.08 mm-0.10 mm) followed by baking in an oven for 10 min at 70° C. The PET side of the hardcoat/PET/adhesive/PET was laminated onto the adhesive coated release liner using a rubber hand roller. Air bubble and defects were carefully avoided by applying tension on the hardcoat/PET/adhesive/PET during lamination. This results in Construction 2. The adhesive of laminated articles was cured with 2 passes using a UV processor equipped with a D-type bulb (600 W, Heraeus Noblelight America/Fusion UV Systems, Gaithersburg, Md.) at 50% power in air at 15 feet/min (4.6 m/min). The curing was performed through the release liner.
Thermoforming of multilayer articles of Construction 1 and Construction 2 was performed on 1 mm edge aluminum phone mold following a described procedure. The hardcoated PET films used in making the multilayer articles were also thermoformed under the same conditions. The thermoforming results are reported in Table 59.
All cited references, patents, and patent applications in the above application for letters patent are herein incorporated by reference in their entirety in a consistent manner. In the event of inconsistencies or contradictions between portions of the incorporated references and this application, the information in the preceding description shall control. The preceding description, given in order to enable one of ordinary skill in the art to practice the claimed disclosure, is not to be construed as limiting the scope of the disclosure, which is defined by the claims and all equivalents thereto.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2018/059776 | 12/7/2018 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62597524 | Dec 2017 | US |
