Note: Descriptions are shown in the official language in which they were submitted.
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COLOR-NEUTR~L UV BLOCKING C'OATING FOR PLASTIC LENS
Reference to Provisional Application
This application claims the benefit of U.S. Provisional Application Serial
No. 60/01 1,537 filed February 13, 1996.
Field of the Invention
This invention relates to stable color-neutral, abrasion resistant coatings
with ultraviolet radiation blocking properties Such coatings are useful on
substrates such as plastic ophthalmic lenses. The coatings of this invention have
a neutral transmittance, a very desirable property particular]y when the coatingare used with ophthalmic lenses where UV ~locking of the UV-A region below
10 about 400 nrn i5 required.
Back~round of the Invention
Ophthalmic lenses are formed from glass or plastics. Plastics include,
for example, polymers based on allyl diglycolcarbonate monomers and
polycarbonates. Ophthalmic lenses are formed as a single integral body or as
laminated lenses that are f'abricated by bonding two lens wafers (i.e., a front
wafer and a back wafer) together with a transparent adhesive. T ~ n~tecl lens
wafers are described, for example, in U.S. Patent Nos. 5,149,181, 4,857,553, and4,645,317.
Commercially avai]able plastic ophthalmic lenses are commonly coated
with a thin polymeric scratch resistance coating. The thickness of the polymericscratch resistance coating will depend, in part, on the substrate material.
Abrasion resistant radiation curable coatings for polycarbonate substrates are
described, for example, in U.S. Patent No. 4,954,591. The vast majority of
ophthalmic lenses are clear.
Absorption of ultraviolet radiation, especially those having higher
wavelengths, by the retina is believed to accelerate or cause retinal injuries such
as macular degeneration. Specifically, epiderniological data correlates UV
sunlight exposure with the incidence of lenticular opacities (cataracts) and
possibly with pseudo exfoliation in the eyes.
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Consequently, there is a demand for finished eyeglass lenses, including
sunglasses, with UV-A, absorption capabilities. Conventional methods of
fabricating plastie len ,es with UV protection have added UV absorbers into the
casting monomer systems that form the ophth~lmic lenses. Unfortunately, UV
S absorbers can interact with the casting monomer system thereby blocking
complete polymerization. This results in a variety of lens defects including
softness. The efi'ect i, exacerbated in prescription lenses where the thicker
regions of the lens Will emit a more intense yellow color. The lens will provideUV-A protection but will be aesthetically undesirable.
U.S. Patent 5,013,608 describes a coatlng composition containing at least
about 3% to about 20'Yo(wt) of coating solids of a tintability enhancing
compound (i.e.. lJV a~bsorbers) in a base resin comprising an aqueous, aqueous-
alcoholic, or alcoholic dispersion of colloidal silica, or a mixture of colloidal
silica with a metal oxide, and a partial condensate of an epoxy-functional silanol
which is blended with a partia] condensate of another silanol. A crosslinking
agent and a curing cat~lyst are added to form purportedly highly tintable
abrasion resistant coating compositions. The coating composition upon curing is
alleged to forrn hard films that provide both abrasion resistance and high levels
of tinting and, op~ionally, absorbance of ultraviolet radiation. Although this
coating composition may be suitable for fabricating tinted articles such as
sunglasses, it is not suitable for fabricating non-tinted articles. The reason is
that these hard films invariably exhibit a yellowish hue.
U.S. Patent 5,3'71,138 describes a UV absorbing polysiloxane resin
composition for coatin,g transparent sheets and plastic spectacle lenses. It is
formed by adding water-based colloidal silica to a silanol blend, heating,
incorporating additives and incorporating a U~f' absorbing material such as
2,2',4,4'-tetrahydroxy-tlenzophenone, benzothiazoles and benzotriazoles, U.S.
Patent 4,233,441 describes an acryloxybenzothiazole copolymerizable UV light
absorber that can be copolymerized with monomers and oligomers by free
radical or radiatioln curing. JP Patent 55093447 describes polycarbonate articles
that are coated with an adhesive and an overcoat, which contains a
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benzotriazole-type UV absorber. This apparently prevents the substrate from
dusting, alkali and solvent attack, and yellowing. U.S. Patent 4,216,267
describes a laminate that comprises a sheet of clear PVC or polycarbonate with
a 0.1-10 mil thiek coating of an acrylic polyurethane and an acrylic UV
absorber. U.S. Patent 4,202,834 describes a copolymerizable UV light absorber,
cyanodiphenyl-acryloxy-alkyl-allyl or substituted allyl ether, purportedly useful
in providing UV protection to radiation cured coatings. U.S. Patent 4,284,485
describes a polyalkylpiperidine derivative as a UV absorber useful in coatings
that are applied to various materials. JP Patent 50054670 describes
polycarbonate moldings coated with solutions prepared by mixing siloxanes and
UV absorbers (benzophenones, triazoles, and salicylates). A
preferred UV absorber is ~-hydroxy-4-octoxybenzophenone is claimed as one of
the examples. ll.S. F'atent 5,013,608 describes a coating composition containing3-20% by weight (of coating solids) of a UV absorber used as a tintability
1 5 enhancer.
As is apparenl, the prior art methods of fabricating films with UV
radiation blocking properties are deficient in I number of respects. First~ for
UV absorbers which are colorless or nearly colorless, UV blocking is
incomplete in the UV-range of 290 nm-380 nm and at longer wavelengths.
These UV absorbers e xhibit maximum absorption at relatively short wavelengths
in the UV spectrum. Subsequently, these U~' absorbers have the undesirable
side effect of imparting a yellow hue to the coating at the concentrations needed
for full UV blocking at these ranges. UV absorbers demonstrating incomplete
UV-A blocking include acrylics, benzothiazoles and benzotriazoles, HALS
(hindered amino light absorbers), monohydroxy benzophenones and salicylates.
Second, when a UV absorber is capable of blocking the full UV-A range
due to an absorption maximum at relatively long UV wavelengths, the UV
absorber is yellow and imparts a ye11Ow hue to the coating. This is caused by
the absorption of visible light, particularly in the blue region (wavelengths above
400 nm) by these UV absorbers. This is part~cularly problematic for ophthalmic
lenses where coatings are relative thin, e.g., from 0.1 llm to 25 ,um, and if full
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blocking of the UV-~ range or at longer wavelengths is desired, the UV
absorbers must have a strong absorption in those wavelength ranges. UV-A
absorbers in thii latter category include the dihydroxy benzophenones such as
2,2',4,4'-tetrahydroxy-benzophenone .
Summary of the Invention
This invention is based in part on the discovery that the polymer
compositions having both UV absorbers and dyes can be employed to produce
transparent, durable lilms that can significantly increase the level of UV
radiation blockage when coated onto substrates including ophthalmic lenses. A
feature of the invention is that the addition of the dyes to the polymer
compositions significantly enhances the optical qualities of the films by
producing a stable, weather resistant coating that is color-neutral, that is, the
coating does not exhibit a hue.
In one aspect. the invention is directed to a composition suitable for
forming a stable color-neutral, transparent coating which includes:
(a) a polymeric composition;
(b) an ultraviolet absorber;
(c) an effective amount of a dye comprising 1-[(4-methylphenyl)amino]-
4-hydroxy-9,10-anthracenedione to neutralize yellow color caused by said
ultraviolet absorber; ;md
(d) a solvent.
In another aspect, the invention is directed to a transparent article
exhibiting low ultraviiolet radiation transmittance which includes:
(a) a substrate; and
(b) a stable color-neutral coating on a surface of said substrate wherein
the coating includes:
(i) a polymeric matrix;
(ii) an ultraviolet absorber; and
(iii) an effective amount of a dye comprising 1-[(4-
methylphenyl)amino]-4-hydroxy-9,10-anthracenedione to neutralize yellow color
caused by said ultraviolet absorber.
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In a further aspect, the invention is directed to a method of fabricating a
transparent article exhibiting low ultraviolet radiation transmittance which
comprises the steps of:
(a) providing a substrate; and
(b) preparing a stable color-neutral coating on a surface of said substrate
wherein the coating comprises:
(i) a polymeric matrix;
(ii~ an ultraviolet absorber; and
(ih) an effective amount of a d~e comprising 1-[(4-
methylphenyl)amino]-4-hydroxy-9,10-anthracenedione to neutralize yellow color
caused by said ultraviolet absorber.
A preferred method of p,~parillg the stable color-neutral coating is by a
process comprising:
(i) preparing a composition comprising a polymeric material, an
ultraviolet absorber, an effective amount of a dye comprising 1-~(4-
methylphenyl)amino]-4-hydroxy-9,l0-anthracenedione to neutralize yellow color
caused by said ultraviolet absorber, and a solvent;
(ii) coating a layer of the composition on a surface of the substrate; and
(iii) removing solvent from the layer to form the coating.
Preferred ultra~iolet absorbers include 2,2'-dihydroxy-4-methoxy
benzophenone~ 2,2'-dihydroxy-4,4'-dimethoxy benzophenone, 2,2',4,4'-
tetrahydroxy benzophenone~ and mixtures thereof. Preferred polymeric materials
include silanols, epoxies, acrylates, methacrylates, polyurethanes, melamines,
and mixtures thereof.
Preferably, for transparent plastic ophthalmic lens, the color-neutral
coating has a UV absorbance of about 98% or more (2% UV transmittance or
less) measured at 380 nm and the coating is about l.S to about S.0 ~m thick.
(Transmittance is defined in accordance with ANSI Z 80.1-l99S). The coating
can substantially absorb UV-A (315 nm - 380 nm) and UV-B (290 nm - 315
nm) radiation.
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The coatings have excellent weatherahility, adhesion and abrasion
resistance. The blue dyes for these applications are most preferably
UV-resistant to avoid degradation of the dye with the consequent destruction of
the neutral transmitta]lce. The blue dye is resistant to degradation or change of
5 color by the coating curing conditions and to the catalysts that bring about this
curing. The UV absorbers must be also weather and coating-curing resistant
and most preferably should be UV stabilizers such as the dihydroxy
benzophenones The coatings used in this invention can be tintable or
non-tintable.
Brief Description of the Drawin~s
Figure I ~s a graph illustrating the spectral transmittance of an uncoated
lens and of hard coated lenses (with and without UV absorbers~.
Detailed DescriPtion of the Preferred Embodiments
This invention is directed to articles OJ substrates that are coated with a
clear transparent, durable, abrasion resistant film (also referred to as a hard
coating) which has ul~raviolet radiation absorbing properties. This film can be
coated onto any suitable substrate such as pla.stic ophthalmic lenses. The film is
prepared from a hard coating composition whlch comprises a mixture of a
polymeric composition, an ultraviolet absorber, and a dye. Incorporation of the
UV absorber not only significantly reduces UV transmittance, but it also
improves the durability of the coated substrate to environmental exposure. The
inventive coating apparently shields the coating/substrate interface, which is
vulnerable to UV degradation, to excessive exposure to UV radiation.
Furthermore, incorpor;~tion of the dye to the coating composition provides a
neutral color to the coating. The dye effectively elimin~tes the yellow hue thatis characteristic of prior art hard coatings and systems where UV cutoff is
achieved by adding the UV absorbers to the monomers.
However, prior to describing the invention in further detail, the following
terms will be defined:
The term ''substrate" refers to a material which preferably has superior
structural and optical properties. Crystalline quart~., fused silica, soda-lime
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silicate glass, and plastics such as from polymers based on allyl diglycol
carbonate monomers (available as CR-39TM f1om PPG Industries, Inc., Hartford,
Conn.) and polycarbonates such as LexanTM, available from General Electric
Co., are preferred substrate materials. Substrates include ophthalmic lenses
5 (including sunglasses). Pret'erred ophthalmic lenses also include l~rnin~e-l lenses
that are fabricated by bonding two lens wafers (i.e., a front wafer and a back
wafer) together with a transparent adhesive. l ~min~d lens wafers are
described, for example, in U.S. Patents 5,149,181, 4,857t~53, and 4,645,317 and
U.K. Patent Application, GB 2,260,937A, all of which are incorporated herein.
10 Suitable substrates further include glass ophthalmic lenses, as described, for
instance, in U.S. Patents 3,899,315 and 3,899,314, both of which are
incorporated herein. Another preferred ophthalmic lens is a plastic lens
available as SpectraliteT'~( from SOLA Optical USA and is described in U.S.
Patent 5,373,033. As used herein, the term "lens" refers to both single integral15 body and laminated types.
The material and dimensions (e.g., thickness) of the substrate employed
will influence the formulation of the coating compositlon. Specifically, most
glasses, for example, absorb ultraviolet light having a wavelength of less than
about 260 nm. Thus, the UV absorber used need only be effective for many
20 applications above about 250 nm in this case. ~onversely, many plastics will
transmit ultraviolet light having a wavelength of less than 260 nm. Thus, the
type of UV absorber can be selected accordingly. Finally, since natural sunlightonly has ultraviolet liyht having a wavelength of about 290 nm and about 400
nm, for ophthalmic lens coatings, the UV absorber employed must be effective
25 in this range.
The term 'coating polymeric composition" or "polymeric composition"
refers to a composition that comprises monomers, oligomers, polymers, and
mixtures thereof, which forrns the polymeric structure of the inventive durable,abrasive resistant coatings which are also referred to as hard coatings.
30 Preferably the monomers, oligomers, and/or polymers can be cured by heat,
and/or actinic radiation. Initiators and/or catalysts can be added to facilitate
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polymerization and crosslinking. Preferred monomers, oligomers, and/or
polymers for the polymeric composition include, for example, silanols, epoxies,
acrylates, methacrylates, melamines, polysiloxanes"?olyurethanes, and mixtures
thereof. Preferred siloxanes include, for example, RISiOl 5 an,d RIR2SiO in
5 which Rl and R2 aJe each independently selected from suitable functional
groups including, for example, g~mm~lycidoxypropyl, methyl, phenyl, ethyl,
propyl, and methacryloxypropyl.
Polysiloxanes are particularly suited for fabricating hard coatings for
plastic lens. A preferred polysiloxane resin is available as TS-56HF (Tokuyama
10 Corporation, Japan). This product comes as two separate components A and B,
one being the polymer system and the other being a catalyst solution. Coating
polymeric compositions are further described in U.S. Patents 4,954,591 and
5,013,608, which an- incorporated herein. The resin compositi,on preferably
includes a solvent to facilitate coating the resin composition onto a substrate
1~ surface. Suitable solvents include, for example, alcohols, glycol ethers, and a~et~s ~e.g., propyl and butyl).
The term "ultraviolet absorber" or "'UV absorber" refers to any suitable
substance that absor,bs ultraviolet radiant energy, then dissipates the energy.
Preferred ultraviolet absorbers include, for example, substituted benzophenones,20 benzotriazoles and diphenyl acrylates and substituted or unsllbstinlted dihydroxy
benzophenones. Particularly useful dihydroxy benzophenones have the
structure:
OH O OH
R2~Rl
preferably where Rl and R2 are each independently selected from the group
consisting of H, OH, ard an alkoxy (i.e., OCnH2n+l) having I to 12 carbons.
Preferred dihydroxy benzophenones include 2,2'-dihydroxy-4-methoxy
30 benzophenone available as Cyasorb UV 24TM from Cytec Corporation,
2,2'-dihydroxy-4,4'dimethoxy benzophenone available as Uvinul D-49TM frorn
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BASF Corp., and 2.2',4.4'tetrahydroxy benzophenone available as Uvinul
3050TM (BASF'~, and mixtures thereof. Use of tetrahydroxybenzophenones in
the coating provides for both a UV cut-off less than 400 nm and a smooth,
clear, cosmetically superior coated film.
The amount of incident ultraviolet light blocked by the inventive coating
can vary depending, for example, on the thickness of the coating and the amount
of UV absorbers emp]oyed. For ophthalmic lenses, an absorbance of about 98%
or more (2% UV transmittance or less) measured at 380 nm is preferred. The
coating can substantially absorb radiation in both the UV-A and UV-B regions.
The term "dye" generally refers to any suitable substance that neutralizes
the yellow color Gaused by some UV absorbing materials. Preferred dyes
include, for example, blue dyes or a mixture of solvent soluble dyes imparting ablue hue. The blue dye is used in combination with the dihydroxy
benzophenones to obtain a neutral color must be also compatible with the
coatings to obtain transparent coatings and preferably must be weather resistant.
A large proportion of prior art blue dyes are not weather resistant. Non-weatherresistant dyes will degrade over a short time relative to the life of the coatedarticle (e.g., ophthalmic lens) so that the yellow color that was being neutralized
becomes evident. Further, the by-product of the degradation may also contribute
to intensify the yellow hue. The blue dyes must also be resistant to chemical
degradation or change of color by ingredients in the coating which normally are
very aggressive such as asids, free radicals, and bases. The blue dyes must
resist heat and actinic radiation used to cure polymeric compositions. A
particularly useful blue: dye which exhibit these characteristic is comprised of 1-
[(4-methylphenyl)amino]4-hydroxy-9,10-anthracenedione that is available as
Kayaset Blue A-2RTM (Nippon Kayaku, Japan~ and which has the following
structure:
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-- 10 --
Many organic dyes are sensitive to the elements. particularly to UV
10 radiation. This is due to the high electron mobility in these dyes which
accounts for their visual color and to the presence of anilino, imino, and
simi~arly UV sensitive chemical groups. Without being bound by theory, the
above referenced anthraquinone derivative is UV resistant because of the
presence within the rnolecule of a hydroxybenzophenone moiety similar to the
15 one present in tJV absorbers that protect against UV radiation. This chemicalgroup converts UV radiation to non-UV radi~tion and heat as in the case of
ordinary 2-hydroxy benzophenones.
METHODOLOGY
The process of fabricating an article coated with a transparent, durable
20 abrasion resiscant film comprises forrning a homogeneous coating polymeric
composition comprising the polymeric composition, UV absorber, dye and
solvent. Appropriate initiators an~/or catalysts are included where necessary.
The mixture is evenly coated onto a substrate, e.g., plastic lens, by conventional
means such as spin coating or dip c~tinE~ The composition is cured to produce
25 a hard coating film. tt has been demonstrated that the UV 380 nm cutoff and
higher ophth~lmic pe,~,lllance are achieved without the yellowing of the hard
coating. The coatings can be tinted if desired~ for instance, to make
"slln~l~c.ces." They can be therrnoplastic or therrnoset, polymerizable or already
polymerized, crosslink~hle and non-crosclink~ble. When curing is needed, the
30 coatings can be cured by the known processes such as by thermal energy or
actic radiation. Radiation and thermally curable coatings are preferred. The
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coatings can be single Jayered or multilayerecl. Typically, the homogeneous
coating polymeric composition comprises about 40% to 85% solvent, preferably
about 70%. (All percentages herein are based on weight.) The proportion of
solvent used wil] depend, in part, on the solubility of the UV absorber and other
5 components. Following removal of the solvent, the coating preferably comprisesabout from 0.5% to 50%, more preferably from 2% to 35% and most preferably
from 6% to 2~% of the U~ absorber. High ~JV absorber levels approaching
50% are to be a~oided since this will decrease the abrasion resistance of the
coating and consequently reduce the adhesion of the coating to the substrate.
The blue dye preferably comprises from about 0.00l% to 0.2% and more
preferably from ().001% to 0.1% of the coating. The ba]ance of the coating
comprises predominantly of the polymer matnx. There is generally an inverse
relationship between the concentrations of the UV absorber and dye and tl-e
thickness of the coating. Specifically, if a thin coating is desired or necessary
for a particular application, then high concentrations of UV absorber and dye are
required to achieve a desired level of UV blocking.
Typically the color-neutral, transparent coating has a thickness that
ranges from about O.l to 20 ,um, and more preferably from 0.8 to 5 ~lm. The
coating is expected to be stable or weather resistant in that it will remain
substantially color-neutral for the expected life of the article or substrate that is
coated. For ophthalmic lenses, it is expected lo be stable for at least about I to
2 years, preferably for about 2 to 3 years. Further, the coatings are resistant to
weather and UV degradation with respect to both physical and optical
characteristics .
It is expected tllat a coating composition comprising a catalyzed polymer,
UV absorber, and dye, that is maintained at ambient temperature, can be
employed for continuous coating applications. Indeed, for large scale coating ofophthalmic lenses, it is expected that up to 1(X~ liters or more of such a coating
eomposition can be formulated and employed to continuously coat lenses
without significant loss of the composition due to excessive polymerization prior
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12
to being coated. The coating formulation (e.g., viscosity) can be adjusted so
that uniform, thin films c~n be produced.
The UV absorber does not adversely affect the polymerization of the
polymeric composition. Further, the dye remains stable in the resin composition
5 and subsequent abrasion resistant coating. The latter was unexpected since
when blue dyes are added to a monomer cast cornposition containing allyl
dig}ycol carbonate monomers, which is comrnonly employed to prepare
ophthalmic lens, the dyes are degraded by the polymerization initiators.
An important advantage to mixing the dye with the polymeric
10 composition and UV absorber is that this produces color-neutral, UV blocking,abrasion resistant coatings of consistent quality. lt has been found that coating
compositions without the dyes produce coatings that have a yellow hue.
Furthermore, the process of dipping the substrate into the dye solution is not
acceptable for producing clear, non-tinted lenses because the necessary color
15 absorption is inconsistent from batch to batch and, indeed, within a given batch
of lenses.
EXPERIMENTAL
ExamPle I A polymeric coating composition comprising 100 grams of the TS-
56HF~TM, 3.13 grams of the UVinul 30~0TM, and 0.01 grams of the Kayaset Blue
20 A-2RTM was prepared as follows: the components A and B of the TS-56HFTM
resin were mixed together and stirred slowly for 24 hours at ambient
temperature. The weighed amount of the UV absorber is then added slowly to
the resin solution. Upon completing the addition, the solution is stirred for 30minutes more. Then, the blue dye is added to the resin solution and stirred for
25 30 minutes. At this point, the solution is ready for coating application.
Referring to Figure 1, this graph shows the transmittance spectrum
curves from an uncoated lens (10), a hard coated lens without UV absorber and
the dye (20), and a hard coated lens with UV absorber and blue dye (30). The
lenses employed were fabricated from poly (diethylene glycol diallyl carbonate).30 Each lens prior to coating was about 2 mm. thick. A coating solution without
the UV absorber and dye was used to coat a lens ~20). A second solution with
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the UA absorber and dye was coated on another lens. Both coatings had a
thickness of 2 ~m. 'rhe hard coating which ~id not have the UV absorber and
dye exhibited a yellowish hue whereas the hard coating which included the UV
absorber and dye was color neutral.
S Measurements show that the transmitlance for the uncoated lens (curve
10) was almost identical to that of the lens that was coated with the hard
coating not having the UV absorber and dye (Curve 20). In contrast, the
inventive lens coated with a hard coating with the UV absorber and dye (curve
30) shows a transmittance of less than 2% at 380 nm. The inventive coated lens
also exhibits good abrasion resistance properties.
In the following Examples 2-4, the weather resistance of the inventive
coating are demonstrated. Inventive and comparative lens substrates were
subjected to various physical and optical tests, the procedures of which are
described as follows:
1. Abrasion resistance test: A proprietary and automated scrubber having
a steel wool #00 surface was utili7.ed. Each sample was scrubbered 75 cycles
with the steel wool. Thereafter, abrasion was detected by visual inspection and
graded in accordance with the following scale: A-No scratches sustained with
rubbing; B-Scratches sustained slightly with rubbing; and C-Scratches sustained
even with weak rubbing. (Uncoated CR-39 lenses are in this category.)
2. Adhesiveness test: The so-called cross-cut tape test, where 11 parallel
lines each in two perpendicularly crossing directions are cut with a sharp razorblade, was employed. The lines are cut at fixed intervals of approximately I
mm, on the surface of the coating of a given sample to produce a total of 100
squares. Thereafter, adhesive cellophane tape is applied to the cut squares, thetape is peeled, and the squares on which the coat film remains are counted. The
adhesiveness is nleasured by the number of squares rem~ining.
3. Hot water resistance test: A sample is placed in boiling water for one
hour.
4. Yellowness index and white li~ht transmittance test: This test
employed a Gardner Pacific Colorimeter XL 835.
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5. Transmittance at 380 nm test: Spectrophotometric transmittance
measured at 38Q nm.
6. Weatherin~ test: Samples were placed outdoors for five weeks,
thereafter, the yellowness index or microcracking of the coatings were measured.
s
Example 2 CR-39 plano lenses, 70 mm in diameter and 2 mm in thickness,
which had been dipped in an aqueous 35% potassium hydroxide solution at
40~C for 60 seconds and then washed, were spin coated with a polymeric
composition comprising hydrolyzed gamma-glycidoxypropryl trimethoxysilane
10 dissolved in methoxypropanol and then cured at 95~C for 4 hours. The solids
content for polymeric composition was 30%. The coating thickness was 2.3 lum.
Similarly. after caustic etching, another set of plano lenses were coated
with the same polymeric composition but funher including a UV absorber
15 (Cyasorb UV 24'M) and dye (Kayaset Blue A-2RTM). The coated lenses were
cured in an oven at 9:5~C for 4 hours. The coating thickness was 2.3 ~m. The
coating contained approximately 21.3~o UV absorber and 0.021% dye. The
lenses that contained ~:he UV absorber with the blue dye had a neutral color.
The test results were ;tS follows:
I Gn , ~tive) I lnvéntive)
coated, coated, UV absorber
no additives and blue dye
yellowness index 14 1.0
25 1~ . % 92 92
white light
abrasion resistance A A
adhesiveness 100 100
hot water l~,;,is~.ce 100 100
30 weall.. ,.illg test, 5 weeks no change no change
, %, at 380 nm. 24 0.2
As is apparent, the inventive coating provided excellent UV blocking and
other optical propertie,.
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Example 3 Caustic-erched and washed CR-3'J plano lenses prepared as in
Example 2 were coated with a polymeric coating composition comprising 100
grams of TS-56HFTM, 3.13 grams of Uvinul 3050TM and 0.01 grams of Kayaset
Blue A-2RTM. An ide:ntical control lens without adding the UV absorber and the
5 blue dye to the composition were also coated. The spin-coated lenses were
cured in an oven The coating thickness for both cases was 2 ~m. The
inventive coating contained approximately 9.5~o UV absorber and 0.03% dye.
The lenses with IJV absorber and the blue dye had a neutral color. The test
results are as follows:
] 0 (Compar~tive) (InventlveJ
coated, co~ted, UV absorber
no addi~ives and blue dye
yellowness index 1 2 1.()
tr~n ~e, %
white ligh~ 92 92
abrasion resistance A A
adhesiveness 100 100
hot water resistance 1()0 100
weathering test, 5 weeks no change no change
re~ %, at 380 nm 27 1.~
Again, as in Example 2, the inventive coating provided excellent UV
30 blocking and other oplical p~opellies.
Example 4 SpectraliteTM plano lenses, from SOLA Optlcal USA, 2 mm in
thickness, were surface-treated and then spin-coated with TR-65TM, a siloxane
coating composition, available from Transitions Corporation. It should be noted
35 that an uncoated SpectraliteTM lens by itself has UV-A blocking capabilities.Another set of SpectraliteTM plano lenses was also coated with TR-65TM that
contained UV absorbers comprising Cyasorb UV 24TM and Uvinul 3050TM, and
Kayaset Blue A-2RTM. The spin-coated lenses for both formulations were cured
in an oven at 105~C for 4 hours. The coating thickness was 2.2 ~Im for all
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lenses. The inventive coatings contained approximate]y 19% Cyasorb UV24TM,
23% Univul 2050TM, and 0.08% dye. The lenses were all color neutral. The
results of the tests are as follows:
(Compara~ive) ~Inventive)
coated, coated, UV absorber
no additives and blue dye
abrasion resistance A B-C
adhesiveness 100 95
As is apparent, high levels of UV absorber content adversely affected the
abrasion resistance and adhesiveness.
Example 5 Inventive coated lenses prepared by the methods described in
Examples 1, 2 and 3 were subjected to accelerated testing by exposure to
radiation from a xenon larnp (without filter) in a HeraeusTM accelerated
weathering device manufactured by DSET Laboratory. After 250 hours, the
20 lenses continued to exhibit excellent UV blocking without loss of white light transmittance or color neutrality.
Although only preferred embodiments of the invention are specifically
disclosed and described above, it will be appreciated that many modifications
and variations of the present invention are possible in light of the above
25 teachings and within the purview of the appended claims without departing from
the spirit and intendecl scope of the invention.
