U.S. patent application number 09/838992 was filed with the patent office on 2001-09-27 for uv blocking lenses and material containing benzotriazoles and benzophenones.
This patent application is currently assigned to Wesley-Jessen Corporation. Invention is credited to Faubl, Hermann.
Application Number | 20010025198 09/838992 |
Document ID | / |
Family ID | 22394323 |
Filed Date | 2001-09-27 |
United States Patent
Application |
20010025198 |
Kind Code |
A1 |
Faubl, Hermann |
September 27, 2001 |
UV blocking lenses and material containing benzotriazoles and
benzophenones
Abstract
A contact lens with enhanced UV blocking to meet ANSI Class 1
specifications includes enhanced effective amounts of two different
UV absorbing compounds. One UV absorber is a benzotriazole
derivative, and the other UV absorber is a benzophenone
derivative.
Inventors: |
Faubl, Hermann; (Lake Bluff,
IL) |
Correspondence
Address: |
Marc V. Richards
BRINKS HOFER GILSON & LIONE
P.O. BOX 10395
CHICAGO
IL
60610
US
|
Assignee: |
Wesley-Jessen Corporation
|
Family ID: |
22394323 |
Appl. No.: |
09/838992 |
Filed: |
April 20, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09838992 |
Apr 20, 2001 |
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09121071 |
Jul 21, 1998 |
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6244707 |
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Current U.S.
Class: |
623/6.6 |
Current CPC
Class: |
G02B 1/043 20130101 |
Class at
Publication: |
623/6.6 |
International
Class: |
A61F 002/16; G02C
007/04 |
Claims
What is claimed is:
1. A contact lens comprising a hydrogel polymer formed by
polymerizing one or more monomers suitable for use in making such
lenses, and incorporating effective amounts of a first ultraviolet
absorber and a second ultraviolet absorber, wherein said first UV
absorber is a benzotriazole compound represented by the formula:
7where R.sup.1a, R.sup.1b, and R.sup.1c are independently hydrogen,
halogen, C.sub.1-C.sub.6 straight or branched chain alkoxy group,
aryl or substituted aryl; R.sup.2 is hydrogen or lower alkyl, aryl
or substituted aryl; R.sup.3 is hydrogen, lower alkyl, aryl,
substituted aryl, or R.sup.4-R.sup.5-R.sup.6, where R.sup.4 is an
oxygen or is absent, R.sup.1 is a linking group selected from
--(CH.sub.2).sub.nO--, --CH(CH.sub.3)CH.sub.2O--,
--CH.sub.2CH(CH.sub.3)O--, --(CH.sub.2).sub.nOCH.sub.2--,
--CH(CH.sub.3)CH.sub.2OCH.sub.2--, or
--CH.sub.2CH(CH.sub.3)OCH.sub.2-- group, or is absent; R.sup.6 is
acrylate, methacrylate, styrene or vinyl; and n is 2 or 3; and
wherein the second UV absorber is a substituted
2-hydroxy-benzophenone according to the formula: 8where R.sup.7a,
R.sup.7b, and R.sup.7c are independently hydrogen, halogen,
C.sub.1-C.sub.6 straight or branched chain alkoxy group, aryl or
substituted aryl; R.sup.8 is a linking group selected from alkyl,
--(CH.sub.2).sub.mO--, --CH(CH.sub.3)CH.sub.2O--,
--CH.sub.2CH(CH.sub.3)O--, --(CH.sub.2).sub.mOCH.sub.2--,
--CH(CH.sub.3)CH.sub.2OCH.sub.2--, or
--CH.sub.2CH(CH.sub.3)OCH.sub.2-- group, or is absent; and R.sup.9
is alkyl, acrylate, methacrylate, styrene or vinyl; and m is 2 or
3.
2. The lens of claim 1 wherein the first UV absorber is a
benzotriazole compound represented by the formula: 9where R.sup.1
is hydrogen, halogen, C.sub.1-C.sub.6 straight or branched chain
alkoxy group, aryl or substituted aryl; and R.sup.5 is a linking
group selected from --(CH.sub.2).sub.nO--,
--CH(CH.sub.3)CH.sub.2O--, --CH.sub.2CH(CH.sub.3)O- --,
--(CH.sub.2).sub.nOCH.sub.2--, --CH(CH.sub.3)CH.sub.2OCH.sub.2--,
or --CH.sub.2CH(CH.sub.3)OCH.sub.2-- group, or is absent; and n is
2 or 3.
3. The lens of claim 2 wherein R.sup.1 is methoxy.
4. The lens of claim 2 wherein R.sup.5 is
--(CH.sub.2).sub.nOCH.sub.2--.
5. The lens of claim 4 wherein n is 3.
6. The lens of claim 1 wherein the second UV absorber is
2-hydroxy-4-acryloxyethoxy-benzophenone,
2-hydroxy-4-methacryloxy-benzoph- enone, or
2-hydroxy-4-methoxy-benzophenone.
7. The lens of claim 6 wherein the second UV absorbing compound is
2-hydroxy-4-acryloxyethoxy-benzophenone.
8. The lens of claim 1 wherein the lens has an average UV
transmittance of less than 10 percent in the UVA range and an
average UV transmittance of less than 1.0 percent in the UVB
range.
9. The lens of claim 8 wherein the average UV transmittance is less
than 1.0 percent in the UVA range.
10. A rigid gas permeable contact lens comprising a polymer formed
by incorporating a monomer suitable for use in making such lenses,
and effective amounts of a first ultraviolet absorber and a second
ultraviolet absorber, wherein said first UV absorber is a
benzotriazole compound represented by the formula: 10where R.sup.1
is a hydrogen, halogen or lower alkoxy, and R.sup.2 and R.sup.3 are
independently hydrogen or lower alkyl; and the second UV absorber
is selected from the group consisting of
2-hydroxy4-acryloxyethoxy-benzophenone,
2-hydroxy-4-methacryloxy-benzophenone and
2-hydroxy4-methoxy-benzophenone- .
11. The lens of claim 10 wherein R.sup.2 and R.sup.3 are
independently hydrogen, methyl or tert-butyl.
12. The lens of claim 10 wherein R.sup.2 is tert-butyl.
13. The lens of claim 10 wherein R.sup.1 is halogen.
14. The lens of claim 10 wherein the first UV absorber is
2-(2'-hydroxy-3 '-tert-butyl-5
'-methylphenyl)-5-chlorobenzotriazole.
15. The lens of claim 10 wherein the second UV absorber is
2-hydroxy-4-methoxy-benzophenone.
16. The lens of claim 10 wherein the first UV absorber is
2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole
and the second UV absorber is 2-hydroxy4-methoxy-benzophenone.
17. An intraocular lens comprising a polymer incorporating
effective amounts of a first ultraviolet absorber and a second
ultraviolet absorber, wherein said first UV absorber is a
benzotriazole compound represented by the formula: 11where
R.sup.1a, R.sup.1b, and R.sup.1c are independently hydrogen,
halogen, C.sub.1 -C.sub.6 straight or branched chain alkoxy group,
aryl or substituted aryl; R.sup.2 is hydrogen, lower alkyl, aryl or
substituted aryl; R.sup.3 is hydrogen, lower alkyl, aryl,
substituted aryl, or R.sup.4-R.sup.5-R.sup.6, where R.sup.4 is an
oxygen or is absent, R.sup.5 is a linking group selected from
--(CH.sub.2).sub.nO--, --CH(CH.sub.3)CH.sub.2O--,
--CH.sub.2CH(CH.sub.3)O- --, --(CH.sub.2).sub.nOCH.sub.2--,
--CH(CH.sub.3)CH.sub.2OCH.sub.2--, or
--CH.sub.2CH(CH.sub.3)OCH.sub.2-- group, or is absent; R.sup.6 is
acrylate, methacrylate, styrene or vinyl; and n is 2 or 3; and
wherein the second UV absorber is a substituted
2-hydroxy-benzophenone according to the formula: 12where R.sup.7a,
R.sup.7b, and R.sup.7care independently hydrogen, halogen,
C.sub.1-C.sub.6 straight or branched chain alkoxy group, aryl or
substituted aryl; R.sup.8 is a linking group selected from alkyl,
--(CH.sub.2).sub.mO--, --CH(CH.sub.3)CH.sub.2O--,
--CH.sub.2CH(CH.sub.3)O--, --(CH.sub.2).sub.mOCH.sub.2--,
--CH(CH.sub.3)CH.sub.2OCH.sub.2--, or
--CH.sub.2CH(CH.sub.3)OCH.sub.2-- group, or is absent; and R.sup.9
is alkyl, acrylate, methacrylate, styrene or vinyl; and m is 2 or
3.
18. The lens of claim 17, wherein the first UV absorber and the
second UV absorber are present in a ratio of between about 3:1 and
1:3 by weight.
19. The lens of claim 17, wherein the total amount of UV absorbers
present is between about 0.8 and about 3.0 percent dry weight of
the lens material.
20. The lens of claim 19, wherein the total amount of UV absorbers
present is between about 1.0 and about 2.0 percent by dry weight of
lens material.
21. The lens of claim 17, wherein the amount of the first UV
absorber present is less than 0.5 percent by dry weight of lens
material so as to minimize any observable yellowish tint.
22. The lens of claim 17 wherein the first UV absorber is a
benzotriazole compound represented by the formula: 13where R.sup.1
is hydrogen, halogen, C.sub.1-C.sub.6 straight or branched chain
alkoxy group, aryl or substituted aryl; and R.sup.5 is a linking
group selected from --(CH.sub.2).sub.nO--,
--CH(CH.sub.3)CH.sub.2O--, --CH.sub.2CH(CH.sub.3)O- --,
--(CH.sub.2).sub.nOCH.sub.2--, --CH(CH.sub.3)CH.sub.2OCH.sub.2--,
or --CH.sub.2CH(CH.sub.3)OCH.sub.2-- group, or is absent; and n is
2 or 3.
23. The lens of claim 22 wherein R.sup.1 is methoxy.
24. The lens of claim 22 wherein R.sup.5 is
--(CH.sub.2).sub.nOCH.sub.2--.
25. The lens of claim 24 wherein n is 3.
26. A UV-absorbing transparent plastic material incorporating at
least two UV absorbing compounds, wherein the first UV absorber is
a benzotriazole compound represented by the formula: 14where
R.sup.1a, R.sup.1b, and R.sup.1c are independently hydrogen,
halogen, C.sub.1-C.sub.6 straight or branched chain alkoxy group,
aryl or substituted aryl; R.sup.2 is hydrogen, lower alkyl, aryl or
substituted aryl; R.sup.3 is hydrogen, lower alkyl, aryl,
substituted aryl, or R.sup.4-R.sup.5-R.sup.6, where R.sup.4 is an
oxygen or is absent, R.sup.5 is a linking group selected from
--(CH.sub.2).sub.nO--, --CH(CH.sub.3)CH.sub.2O--,
--CH.sub.2CH(CH.sub.3)O--, --(CH.sub.2).sub.nOCH.sub.2--,
--CH(CH.sub.3)CH.sub.2OCH.sub.2--, or
--CH.sub.2CH(CH.sub.3)OCH.sub.2-- group, or is absent; R.sup.6 is
acrylate, methacrylate, styrene or vinyl; and n is 2 or 3; and
wherein the second UV absorber is a substituted
2-hydroxy-benzophenone according to the formula: 15where R.sup.7a,
R.sup.7b, and R.sup.7care independently hydrogen, halogen,
C.sub.1-C.sub.6 straight or branched chain alkoxy group, aryl or
substituted aryl; R.sup.8 is a linking group selected from alkyl,
--(CH.sub.2).sub.mO--, --CH(CH.sub.3)CH.sub.2O--,
--CH.sub.2CH(CH.sub.3)O- --, --(CH.sub.2).sub.mOCH.sub.2--,
--CH(CH.sub.3)CH.sub.2OCH.sub.2--, or
--CH.sub.2CH(CH.sub.3)OCH.sub.2-- group, or is absent; and R.sup.9
is alkyl, acrylate, methacrylate, styrene or vinyl; and m is 2 or
3.
27. The plastic material of claim 26 wherein the first UV absorber
is a benzotriazole compound represented by the formula: 16where
R.sup.1 is hydrogen, halogen, C.sub.1-C.sub.6 straight or branched
chain alkoxy group, aryl or substituted aryl; and R.sup.5 is a
linking group selected from --(CH.sub.2).sub.nO--,
--CH(CH.sub.3)CH.sub.2O--, --CH.sub.2CH(CH.sub.3)O--,
--(CH.sub.2).sub.nOCH.sub.2--, --CH(CH.sub.3)CH.sub.2OCH.sub.2--,
or --CH.sub.2CH(CH.sub.3)OCH.sub.2-- group, or is absent; and n is
2 or 3.
28. The plastic material of claim 27 wherein R.sup.1 is
methoxy.
29. The plastic material of claim 27 wherein R.sup.5 is
--(CH.sub.2).sub.nOCH.sub.2--.
30. The plastic material of claim 29 wherein n is 3.
31. The plastic material of claim 26 wherein the second UV absorber
is 2-hydroxy4-acryloxyethoxy-benzophenone,
2-hydroxy-4-methacryloxy-benzophe- none, or
2-hydroxy-4-methoxy-benzophenone.
32. The plastic material of claim 26 wherein the second UV
absorbing compound is 2-hydroxy4-acryloxyethoxy-benzophenone.
33. The plastic material of claim 26 wherein the lens has an
average UV transmittance of less than 10 percent in the UVA range
and an average UV transmittance of less than 1.0 percent in the UVB
range.
34. The plastic material of claim 33 wherein the average UV
transmittance is less than 1.0 percent in the UVA range.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to transparent plastic materials for
optical use, and particularly to ocular devices which absorb
ultraviolet radiation, and to their production from ultraviolet
absorbing compounds, such as by copolymerizing the compounds with
suitable reactive monomers.
[0002] Contact lenses containing compounds for blocking ultraviolet
("UV") light have been on the market for several years. Such lenses
are useful to all who live in areas where bright sunlight is
common. As UV radiation is likely to be a cause of cataracts and
senile macular degeneration, everyone who wears contact lenses can
benefit from the type which block this radiation. Younger persons,
whose eye lenses transmit more ultraviolet radiation than do those
of older persons, also should be concerned with providing
additional protection.
[0003] Ultraviolet blocking lenses are especially useful for those
who have had the natural lens of the eye removed, since the natural
lens has UV absorption properties that help to protect the interior
of the eye. Hence, UV absorbing intraocular lenses (IOLs) are also
highly desirable, since such lenses are implanted in place of the
eye's natural lens.
[0004] Loshaek discovered the use of polymerizable UV absorbing
compounds for producing contact and intraocular lenses in the early
1970's, e.g., as shown in U.S. Pat. No. Re. 33,477. More recently,
substituted 2-phenyl benzotriazole compounds having a polymerizable
acrylic group have been used to produce contact lenses, e.g., as in
U.S. Pat. No. 4,716,234 to Dunks et al. The UV absorption
technology has been applied primarily to rigid, gas permeable
lenses, most commercially available soft lenses do not contain UV
absorbers.
[0005] Hydrogels are desirable for use in lenses, particularly
IOLs. However, because of their hydrophilic nature and expanded
structure, it has been difficult to incorporate UV absorbing
compounds into hydrogels. Prior art UV absorbers are generally
hydrophobic and have limited solubility in hydrogels. Due in part
to this limited solubility, it has been difficult to copolymerize
UV absorbers with hydrogel forming monomers. UV absorbers are
preferably copolymerized, rather than physically entrapped within
the hydrogel, to prevent the absorber from being leached out of the
UV absorbing hydrogel when the hydrogel is in the aqueous
environment of the eye or stored in solution.
[0006] In addition to problems of incorporation of UV absorbers
into hydrogels, UV absorbers having the required characteristics
such as UV absorption between 300-400 nm and hydrolytic stability
have been difficult to synthesize.
[0007] Recently, Collins, et al. discovered a new class of
benzotriazoles that are useful in soft contact lenses, as shown in
U.S. Pat. No. 5,637,726. The compounds absorb UV light very well at
the upper end of the UV spectrum. These benzotriazoles copolymerize
well into hydrogel polymers without the problems of leaching out.
Also, effective amounts of these benzotriazoles incorporated into
the contact lens polymer do not negatively affect the properties of
the polymer. Also, these compounds increase the refractive index
and optic potential of the contact lenses, allowing for thinner
lenses with enhanced oxygen permeability. These compounds also have
a higher cut-off, up to 400 nm, to block more light in the UVA
range.
[0008] While contact lenses containing a UV absorbing compound are
now commercially available, these lenses do not block all of the UV
light from entering the eye, and typically only block about 90% of
the entire UV range. The UV range is generally broken in to two
subranges, known as UVA and UV B. ANSI Class 1 specifications for
UV absorption require an average percent transmittance of less than
1.0% at 280-315 nm (UVB range) and only less than 10% at 316-380 nm
(UVA range). Commercially available UV absorbing contact lenses do
not meet this standard.
[0009] The difficulty in obtaining a UV blocking contact lens that
meets Class 1 standards by using a benzotriazole, as described by
Collins et al., is that one has to use so much benzotriazole that
the lens also absorbs significant amount of light at the upper end
of the UVA range and into the visible light range. This results in
an observable yellowish tint in the contact lens, which is not
appealing to consumers. More importantly, this yellowish tint
throws off the cosmetic appearance of colored contact lenses. In
addition, too much benzotriazole, or other UV absorbing compound,
can adversely affect the properties of the lens polymer, such as
durability, flexibility, hydrophilicity, stability to sterilizing
regimes, etc. Also, the compound may be present in too high
quantities for all of it to covalently bond with the other monomers
during the polymerization, resulting in excessive residual monomer
content that may gradually leach out during use.
[0010] Hung et al., U.S. Pat. No. 4,963,160, proposes a solution to
some of these problems by bonding two different UV absorbing
compounds that each have a different UV absorbing spectra onto a
triazine derivative, which is then applied as a coating onto a
polymeric lens. The UV absorbers are preferably selected to provide
a UV absorbing agent with the broadest UV absorption range
possible. Hung et al. disclosed embodiments of these UV absorbing
agents that include p-aminobenzoic acid and a benzotriazole, or
p-aminobenzoic acid and a benzophenone. The use of this UV
absorbing agent has certain limitations because the UV absorbing
compounds can only be used in a one-to-one mole ratio, so that the
UV absorption spectra of the lens cannot be optimized Also, there
are difficulties to achieve consistent coating thicknesses.
SUMMARY OF THE INVENTION
[0011] The present invention overcomes some of these problems
unsolved by prior art UV blocking lenses by providing a plastic
material, preferably in the form a of an ocular device such as a
contact lens or an intraocular lens, comprising a polymer formed by
incorporating one or more monomers suitable for use in making such
lenses, and effective amounts of a combination of a first
ultraviolet absorber and a second ultraviolet absorber, wherein the
first UV absorber is a benzotriazole compound represented by the
formula: 1
[0012] where R.sup.1a, R.sup.1b, and R.sup.1c are independently
hydrogen, halogen, C.sub.1-C.sub.6 straight or branched chain
alkoxy group, aryl or substituted aryl; R.sup.2 is hydrogen, lower
alkyl, preferably tert-butyl, aryl or substituted aryl; R.sup.3 is
hydrogen, lower alkyl, aryl, substituted aryl, or
R.sup.4-R.sup.5-R.sup.6, where R.sup.4 is an oxygen or is absent,
R.sup.5 is a linking group selected from --(CH.sub.2).sub.nO--,
--CH(CH.sub.3)CH.sub.2O--, --CH.sub.2CH(CH.sub.3)O- --,
--(CH.sub.2).sub.nOCH.sub.2--, --CH(CH.sub.3)CH.sub.2OCH.sub.2--,
or --CH.sub.2CH(CH.sub.3)OCH.sub.2-- group, or is absent; R.sup.6
is acrylate, methacrylate, styrene or vinyl; and n is 2 or 3;
[0013] and wherein the second UV absorber is a substituted
2-hydroxy-benzophenone according to the formula: 2
[0014] where R.sup.7a, R.sup.7b, and R.sup.7c are independently
hydrogen, halogen, C.sub.1-C.sub.6 straight or branched chain
alkoxy group, aryl or substituted aryl; R.sup.8 is a linking group
selected from alkyl, --(CH.sub.2).sub.mO--,
--CH(CH.sub.3)CH.sub.2O--, --CH.sub.2CH(CH.sub.3)O- --,
--(CH.sub.2).sub.mOCH.sub.2--, --CH(CH.sub.3)CH.sub.2OCH.sub.2--,
or --CH.sub.2CH(CH.sub.3)OCH.sub.2-- group, or is absent; and
R.sup.9 is alky, acrylate, methacrylate, styrene or vinyl; and m is
2 or 3.
[0015] Other aspects and advantages of the present invention will
be apparent from the following detailed description.
BRIEF DESCRIPTION OF THE DRAWING
[0016] FIG. 1 shows the UV transmission spectra from the
formulations of Example 5.
DETAILED DESCRIPTION OF THE DRAWING AND PREFERRED EMBODIMENTS OF
THE INVENTION
[0017] In the following description and claims, the term "percent"
will be used to represent percentage by weight, unless the context
indicates otherwise.
[0018] Ocular devices contemplated in connection with the present
invention include, without limitation, windows, lenses for
eyeglasses and instruments such as binoculars, goggles, face
shields, contact lenses, intraocular lenses and the like. Contact
lenses can include both those for correcting defective visual
acuity and the so-called "bandage lenses" which are used in
treating eye disorders, as well as the purely cosmetic lenses used
for purposes such as changing the apparent eye color.
[0019] For convenience, the following acronyms and abbreviations
are used to describe the below-identified compounds, unless
otherwise noted:
[0020] A. UV Absorbing Compounds
[0021] 1. BZT
[0022]
2-(2'-hydroxy-3'-tert-butyl-5'-(3"-(4'"-vinylbenzoxy)propoxy)phenyl-
)-5-methoxy-2H-benzotrizole; C.sub.29H.sub.33N.sub.3O.sub.4
[0023] 2. UVAM
[0024]
2-(2'-hydroxy-3'-tert-butyl-5'-vinylphenyl)-5-chloro-2H-benzotrizol-
e; C.sub.18H.sub.18CIN.sub.3O
[0025] 3. BP
[0026] 2-hydroxy-4-acryloxyethoxy-benzophenone;
C.sub.18H.sub.16O.sub.5
[0027] 4. MBP
[0028] 2-hydroxy4-methoxy-benzophenone; C.sub.14H.sub.12O.sub.3
[0029] B. Lens Monomers and Structures
[0030] 1. HEMA; Hydroxyethyl methacrylate;
C.sub.6H.sub.10O.sub.3
[0031] CH.sub.2.dbd.C(CH.sub.3)CO.sub.2CH.sub.2CH.sub.2OH
[0032] 2. EOEMA; Ethoxyethyl methacrylate;
C.sub.8H.sub.14O.sub.3
[0033]
CH.sub.2.dbd.C(CH.sub.3)CO.sub.2CH.sub.2CH.sub.2OCH.sub.2CH.sub.3
[0034] 3. EDMA; Ethyleneglycol dimethacrylate;
C.sub.10H.sub.14O.sub.4
[0035] [CH.sub.2.dbd.C(CH.sub.3)CO.sub.2CH.sub.2--].sub.2
[0036] 4. MAA; Methacrylic acid; C.sub.4H.sub.6O.sub.2
[0037] CH.sub.2.dbd.C(CH.sub.3)CO.sub.2H
[0038] 5. NVP; N-vinyl pyrrolidone; C.sub.6H.sub.9NO
[0039] (CH.sub.2).sub.3C(O)N--CH.dbd.CH.sub.2
[0040] 6. AMA; Allyl methacrylate; C.sub.7H.sub.10O.sub.2
[0041] CH.dbd.C(CH.sub.3)CO.sub.2CH.sub.2CH.dbd.CH.sub.2
[0042] 7. MMA; Methyl methacrylate; C.sub.5H.sub.8O.sub.2
[0043] CH.sub.2.dbd.C(CH.sub.3)CO.sub.2CH.sub.3
[0044] 8. DMA; N,N-Dimethylacrylamide; C.sub.5H.sub.9NO
[0045] CH.sub.2.dbd.CHC(O)N(CH.sub.3).sub.2
[0046] 9. GMA; Glyceryl methacrylate; C.sub.6H.sub.12O.sub.4
[0047] CH.dbd.C(CH.sub.3)CO.sub.2CH.sub.2CH(OH)CH.sub.2OH
[0048] 10. TEGDMA; Tetraethylene glycol dimethacrylate,
[0049]
CH.sub.2.dbd.C(CH.sub.3)COOCH.sub.2(CH.sub.2OCH.sub.2).sub.3CH.sub.-
2OOC(CH.sub.3)C.dbd.CH.sub.2
[0050] 11. Polymerization initiators
[0051] VAZO 64; 2,2'-azobis(2-methylpropanenitrile);
C.sub.8H.sub.12N.sub.4
[0052] [C(CH.sub.3).sub.2(CN)--N.dbd.].sub.2
[0053] VAZO 52; 2,2'-azobis(2,4-dimethylpentanenitrile);
C.sub.14H.sub.24N.sub.4
[0054] [C(C.sub.4H.sub.9)(CH.sub.3)(CN)--N.dbd.].sub.2
[0055] tBPP; t-Butyl peroxypivalate; C.sub.9H.sub.12O.sub.3
[0056] (CH.sub.3)CO.sub.2C(O)C(CH.sub.3).sub.3
[0057] IPP; Isopropylperoxydicarbonate; C.sub.8H.sub.14O.sub.6
[0058] [(CH.sub.3).sub.2CHOC(O)O--].sub.2
[0059] The present invention includes a contact lens, intraocular
lens, or an optical quality plastic comprising a polymer formed by
incorporating one or more monomers suitable for use in making such
lenses, and effective amounts of a first ultraviolet absorber and a
second ultraviolet absorber to provide amounts of UV absorption to
meet ANSI Class 1 specifications without creating an observable
yellowish tint to the lens, wherein the first UV absorber is a
benzotriazole compound represented by the formula: 3
[0060] where R.sup.1a, R.sup.1b, and R.sup.1c are independently
hydrogen, halogen, C.sub.1-C.sub.6 straight or branched chain
alkoxy group, aryl or substituted aryl; R.sup.2 is hydrogen, lower
alkyl, preferably tert-butyl, aryl or substituted aryl; R.sup.3 is
hydrogen, lower alkyl, aryl, substituted aryl, or
R.sup.4-R.sup.5-R.sup.6, where R.sup.4 is an oxygen or is absent,
R.sup.5 is a linking group selected from --(CH.sub.2).sub.nO--,
--CH(CH.sub.3)CH.sub.2O--, --CH.sub.2CH(CH.sub.3)O- --,
--(CH.sub.2).sub.nOCH.sub.2--, --CH(CH.sub.3)CH.sub.2OCH.sub.2--,
or --CH.sub.2CH(CH.sub.3)OCH.sub.2-- group, or is absent; R.sup.6
is acrylate, methacrylate, styrene or vinyl; and n is 2 or 3;
[0061] and wherein the second UV absorber is a substituted
2-hydroxy-benzophenone according to the formula: 4
[0062] where R.sup.7a, R.sup.7b, and R.sup.7c are independently
hydrogen, halogen, C.sub.1-C.sub.6 straight or branched chain
alkoxy group, aryl or substituted aryl; R.sup.8 is a linking group
selected from alkyl, --(CH.sub.2).sub.mO--,
--CH(CH.sub.3)CH.sub.2O--, --CH.sub.2CH(CH.sub.3)O- --,
--(CH.sub.2).sub.mOCH.sub.2--, --CH(CH.sub.3)CH.sub.2OCH.sub.2--,
or --CH.sub.2CH(CH.sub.3)OCH.sub.2-- group, or is absent; and
R.sup.9 is alkyl, acrylate, methacrylate, styrene or vinyl; and m
is 2 or 3.
[0063] For the first UV absorber, the benzotriazole derivatives,
preferred substituent groups for R.sup.1 are H, Cl and CH.sub.3O--,
more preferably CH.sub.3O--. Preferably, R.sup.1a and R.sup.1c are
hydrogen when R.sup.1b is methoxy. The preferred substituent group
for R.sup.2 is tert-butyl. R.sup.3 is preferably oxygen. R.sup.4 is
preferably oxygen. R.sup.5 is preferably selected from
--(CH.sub.2).sub.3OCH.sub.2-- and --(CH.sub.2).sub.2OCH.sub.2--,
more preferably R.sup.5 is --(CH.sub.2).sub.3OCH.sub.2--. R.sup.6
is preferably methacrylate or styrene. The more preferred compound
is one wherein R.sup.1 is CH.sub.3O--; R.sup.2 is
--C(CH.sub.3).sub.3; R.sup.4 is O; R.sup.5 is
--(CH.sub.2).sub.3OCH.sub.2--; and R.sup.6 is styrene. The aryl
group may optionally be substituted with halogen, alkyl,
halogenated alkyl, alkoxy, alkenyl, alkynyl, and amino groups.
[0064] Generally, benzotriazole derivatives that have UV absorbing
qualities comparable to those described specifically in this
application, may be useful alternatives to those defined by this
invention. One skilled in the art may be able to find or synthesize
such compounds and apply them in accordance with the teaching of
this invention without undue experimentation.
[0065] A preferred class of benzotriazole compounds are represented
by the formula: 5
[0066] where R.sup.1 and R.sup.5 are as defined above.
[0067] Specifically, some of the preferred benzotriazole compounds
of this invention are prepared following the procedures described
in U.S. Pat. No. 5,637,726, to Collins et al., incorporated herein
by reference. For example, reacting a vinylbenzyl chloride with a
2-[2'-hydroxy-5'-(gamma-h-
ydroxyalkoxy)-3'-t-butylphenyl]-5-(alkoxy [or
halo])-2H-benzotriazole one obtains the compound of the above
formula. The starting benzotriazole can be prepared by the method
described in Examples 1-3 of U.S. Pat. No. 4,716,234 to Dunks et
al., which is incorporated herein by reference, substituting
4-halo-2-nitroaniline for the 4-methoxy-2-nitroaniline when it is
desired to make a halogen group, and using any of
3-chloro-1-propanol, 2-chloroethanol, 2-chloro-1-propanol or
1-chloro-2-propanol to produce the desired group for R.sup.2. Those
skilled in the art will be aware of other groups which can be
substituted for these chloro groups, such as other halogens, and
for groups such as methoxy. By appropriate choice of the
substituted nitroaniline, R.sup.1 can be made to occupy ring
positions other than that shown in the above structural formula
[0068] Alternatively, the first UV absorbing compound may
preferably be a benzotriazole derivative represented by the
formula: 6
[0069] where R.sup.1 is a hydrogen, halogen or lower alkoxy;
R.sup.2 and R.sup.3 are independently hydrogen or lower alkyl.
Preferably, R.sup.1 is halogen, with chlorine being more preferred.
Preferably, R.sup.2 and R.sup.3 are independently hydrogen, methyl
or tert-butyl. More preferably, R.sup.2 is tert-butyl. The
non-polymerizable benzotriazole derivative of this formula is
preferably used for rigid gas permeable contact lenses. A preferred
compound is 2-(2'-hydroxy-3'-tert-butyl-5'-me-
thyl-phenyl)-5-chlorobenzotriazole, which is manufactured by
Ceiba-Geigy Corp., and commercially available under the trademark
TINUVIN-326.
[0070] For the second UV absorbers, the benzophenone compounds,
preferably R.sup.7 is hydrogen, halogen or alkoxy. More preferably,
R.sup.7 is hydrogen or p is zero. R.sup.8 is preferably alkyl,
--(CH.sub.2).sub.nO--, or absent. R.sup.9 is preferably is alkyl,
acrylate, or methacrylate. The second UV absorbers are selected
from the group exemplified by
2-hydroxy4-acryloxyethoxy-benzophenone,
2-hydroxy4-methacryloxy-benzophenone, and
2-hydroxy4-methoxy-benzophenone- . More preferably, the selected
compounds are 2-hydroxy4-acryloxyethoxy-be- nzophenone or
2-hydroxy4-methacryloxy-benzophenone. Most preferably,
2-hydroxy-4-acryloxyethoxy-benzophenone is selected for use in
hydrogel lenses. For rigid gas permeable contact lenses or other
rigid plastics, it is preferred to use
2-hydroxy-4-methoxy-benzophenone. These compounds are well-known
and described, and are either commercially available or easily
synthesized.
[0071] Typically, useful amounts of the UV absorbing compounds in a
polymer range from about 0.01 percent to about 25 percent,
depending upon the intended use for the polymer. In general, it
will be desirable to minimize the amount of compound used, so that
the physical and chemical properties of the base polymer (other
than UV absorption) will not be significantly or detrimentally
effected. For contact and intraocular lenses made primarily from
acrylate and methacrylate polymers, about 0.05 to about 10 percent
of UV absorbers can be used. For creating lenses that meet Class 1
specifications and do not have observable yellowish tints, less
than 0.4 percent of the first UV absorbing compound (benzotriazole)
may be used. The preferred total amounts of UV absorbers are
between about 0.8 and about 3.0 percent, with between about 1.0 and
about 2.0 percent being more preferred. The desired ratio of the
amount of the first UV absorber to the second UV absorber (e.g.
BZT:BP) is between about 5:1 and about 1:3, preferably between
about 3:1 and 1:3.
[0072] The amounts of the individual UV absorbing compounds used
depend on the polymer base, thickness of the lens, water or solids
content and desired level of UV absorption. The preferred amounts
will, of course, vary depending upon the water content and
thickness of the lenses. For example, a lens that is twice as thick
will need only half the concentration of UV absorber, assuming its
water content is the same. On the other hand, a lens twice as thick
with doubled water content will require the same concentration of
UV absorber.
[0073] In practice, the first and second UV absorbers are present
in amounts to provide an enhanced reduction in the level of UV
transmission compared to the level of UV transmission than can be
achieved by using the same total amount of one UV absorbing
compound alone. In other words, the two UV absorbing compounds in
combination enhance the total effective UV light blockage. Greater
blocking of UV light can be achieved using lesser total amounts of
the combination of BZT and BP than using a like amount of either
BZT or BP alone.
[0074] The UV absorbing compounds can be copolymerized with a large
number of unsaturated and other monomers to produce polymers having
enhanced UV blocking properties. Representative useful monomers
include, without limitation:
[0075] (a) olefins, either straight- or branched-chain, including
ethylene, propene, butenes, pentenes and the like;
[0076] (b) dienes, such as butadiene, and trienes;
[0077] (c) styrene and substituted styrenes;
[0078] (d) silanes;
[0079] (e) halogen-containing vinyl or vinylidene compounds, vinyl
alcohols or esters, and the like;
[0080] (f) acrylic and methacrylic acids, esters, amides, nitriles
and the like;
[0081] (g) silicon substituted alkyl or aryl acrylic or methacrylic
esters, including alkyl silicates;
[0082] (h) fluorinated alkyl or aryl substituted acrylic or
methacrylic esters;
[0083] (i) vinyl pyrrolidones;
[0084] (j) vinyl silanes;
[0085] (k) vinyl sulfones;
[0086] (l) reactive mixtures of polyamines or polyhydroxy compounds
and polybasic acids;
[0087] (m) epoxides, alkylene oxides or ethers;
[0088] (n) alkylidene or phenylene oxides;
[0089] (o) reactive mixtures of carboxylic or carbonic acids and
polyhydroxy compounds; and
[0090] (p) reactive mixtures of isocyanates and polyhydroxy
compounds.
[0091] Those skilled in the art will recognize that various of the
monomers and reactive mixtures listed above, as well as others, can
be copolymerized, and that the compounds of this invention can be
used to form UV absorbing polymers with such mixtures of monomers.
Copolymers which are formed may be random, block or grafted
polymers.
[0092] In addition to incorporating the compounds into polymers by
copolymerization, it is possible to form a new WV absorbing polymer
structure by condensing or otherwise coupling absorbing compounds
with a polymerized material having pendant reactive groups, or to
form a WV absorbing polymer by physically dispersing the compounds
as additives in a formed polymer, e.g., adding a compound to a
polymer melt, provided that the ratio of the different UV absorbing
compounds in the polymer can be adjusted to achieve the desired
enhanced UV blocking.
[0093] Hydrogels for use in contact lenses or IOLs ideally should
contain a UV absorbing compound. This is particularly the case when
the lens is to be used to replace the natural lens of the eye lost
to injury or disease. The present invention is directed to UV
absorbing hydrogels having the following characteristics.
[0094] First, the UV absorbing monomer of the UV blocking hydrogel
should block UV radiation between about 300-400 nm, because the
purpose of incorporating a UV absorber into a hydrogel is to
prevent transmittance of UV radiation to the retina. As previously
discussed, this function is normally performed by the eye's natural
lens, which, however, is damaged by UV radiation. Although the UV
blocking hydrogel should block UV radiation between about 300 to
400 nm, it is desirable that absorbance sharply decrease above 400
nm. If absorbance does not sharply decrease above 400 nm, the UV
absorbing hydrogel will take on a significant yellow tint. In some
cases, however, some yellow tint may be desired. For example, it
has been thought that increased light absorbance in this range by
spectacles, goggles, contact lenses, etc., enhances visual
acuity.
[0095] Second, it is desirable to incorporate a UV absorbing
monomer into the hydrogel at the lowest concentration possible in
order to minimize the impact of the compound on the structure of
the hydrogel. Hydrogels are particularly susceptible to being
adversely affected by the addition of other compounds due to their
expanded structure. Most UV absorbing monomers with good UV
absorbing characteristics are more hydrophobic than
hydrogel-forming monomers. The addition of any significant amount
of a UV absorbing monomer to a hydrogel forming monomer decreases
the water content of the resulting UV absorbing hydrogel. This can
adversely impact the desirable properties of the hydrogel.
Therefore, it is desirable to use at least two different UV
absorbing compounds which in combination have an enhanced effective
blocking of UV radiation, thereby minimizing the concentration of
absorber required.
[0096] Third, it is important the UV absorbing hydrogel be stable
as a copolymer and in particular exhibit long-term hydrolytic
stability. This is a particularly important requirement when the
hydrogel is to be used as an IOL and surgically implanted within
the eye, since IOLs are generally intended to remain in the eye
indefinitely.
[0097] Fourth, the UV absorbing compound to be incorporated into
the hydrogel must be soluble in the hydrogel-forming monomer so
that it can be copolymerized with the hydrogel-forming monomer. It
is necessary that the UV absorber be copolymerized with the
hydrogel-forming monomer due to the expanded nature of hydrogels.
Because of this expanded structure it is impractical to rely on
imbedding or dispersing UV-absorbing compounds within the hydrogel
as can be done with rigid-gas-permeable (RGP) type lenses.
Moreover, copolymerization prevents the UV absorber from being
leached from the hydrogel while in the eye or in a storage
solution. At a minimum, the UV absorbing monomer should be soluble
in the hydrogel forming monomer in an amount sufficient to provide
the desired degree of UV absorbance in the UV blocking
hydrogel.
[0098] Ocular devices or UV blocking optical plastics, in
accordance with the invention, may be produced by incorporating a
first UV absorbing compound, a second UV absorbing compound, and at
least one monomeric compound suitable for producing an ocular
device, preferably in the case of contact and intraocular lenses,
hydroxyethyl methacrylate, N-vinyl pyrrplidone, alkyl methacrylates
such as methyl methacrylate, aryl methacrylates, silicone
methacrylate, glyceryl methacrylate, fluorinated methacrylates,
alkyl substituted styrene, or combination thereof. Of course, other
lens-producing monomers may be used.
[0099] Contact and intraocular lenses in accordance with invention
may be hydrophilic, hard, or rigid-gas-permeable (RGP), depending
on the monomer or combination thereof in which the UV-absorbing
compounds of the invention are incorporated. In the case of hard or
RGP lenses, it is preferred to have the UV absorbers dispersed in
the polymer matrix. In the case of hydrophilic lenses, it is
preferred to have the UV absorbers copolymerized with the base lens
monomers.
[0100] Copolymerization may take place by any of the methods well
known within the ocular device industry, e.g., by heat or UV light,
or with a suitable initiator. Polymerization temperatures are
typically 25.degree. to 140.degree. C., more preferably 30.degree.
to 100.degree. C., for 5 minutes to 96 hours, more preferably 1 to
24 hours. Suitable polymerization catalysts include
azobisisobutyronitrile, available from E. I. DuPont de Nemours
Corporation, Wilmington, Del. U.S.A. as Vazo 64.TM., 2,2'-azobis
(2,4-dimethylpentanenitrile), available from DuPont as Vazo
52.TM.m, and 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy) hexane,
available from Elf-Atochem, Buffalo, N.Y. U.S.A. as Lupersol
256.TM., as well as other peroxides.
[0101] If UV light is used to initiate the polymerization, its
intensity should be about 0.1 to about 50 milliwatts per square
centimeter, more preferably 1 to 5 mW/cm.sup.2. Generally, the time
required is from 1 minute to 10 hours, preferably from 5 minutes to
2 hours. The temperature is between about 20 and 50.degree. C.,
preferably 25-30.degree. C. Light-created radicals are derived from
the initiators such as Vazo 52 and the like.
[0102] Lenses of the invention may also be produced by first
polymerizing a rod of the copolymer, cutting the rod into bonnets
or buttons, and machining the bonnets or buttons into lenses, as is
well known in the art. If the polymer undergoes a UV cure, the
monomer mixture may also be heat cured after exposure to the UV
source. Alternatively, the lenses may be produced by any of the
known molding or casting techniques, such as the methods referred
to by Kindt-Larsen et al. in U.S. Pat. No. 5,039,459. The exact
manner used for polymerization and lens shaping is a matter of
choice and is not critical to this invention.
[0103] The following examples further describe the invention, but
are not to be construed as limiting the scope of the invention.
Generally, unless otherwise noted, the relative amounts of
ingredients are shown on a dry weight basis. In examples where the
total ingredients do not total exactly 100 percent or 1.000
fraction, the amount of ingredients should be considered to be
approximate relative proportions.
EXAMPLE 1
[0104] HEMA Based Class I Lens
1 Ingredient Weight Fraction of Polymer Base HEMA 0.5788 EOEMA
0.0647 EDMA 0.0148 MAA 0.0106 BZT 0.0044 BP 0.0096 IPA (Isopropyl
alcohol) 0.3099 Vazo 52 0.0072 TOTAL 1.0000
[0105] The hydrated lens had a water content of 53% with a center
thickness of 0.083 mm. The average light transmission was
%T(280-315nm)=0.02% and %T(315-380 nm)=2.2%.
EXAMPLE 2
[0106] NVP Based Class I Lens
2 Ingredient Weight Fraction MMA 0.2954 NVP 0.6743 AMA 0.0016 BZT
0.0063 BP 0.0136 Vazo 64 0.0088 TOTAL 1.0000
[0107] The hydrated lens had a water content of 74%
EXAMPLE 3
[0108] GMA-Based Class I Lens
3 Ingredient Weight Fraction GMA 0.6897 MMA 0.2871 EDMA 0.0034 BZT
0.0062 BP 0.0134 IPP 0.0002 TOTAL 1.0000
[0109] The hydrated lens had a water content of 38%
EXAMPLE 4
[0110] GMA/MMA-Based Class I Lens
4 Ingredient Weight Fraction GMA 0.5282 MMA 0.4303 Water 0.0196
EDMA 0.0010 BZT 0.0062 BP 0.0137 tBPP 0.0010 TOTAL 1.0000
EXAMPLE 5(a-h)
[0111] HEMA-Based Lenses
5 % Weight Ingredient 5a 5b 5c 5d 5e 5f 5g 5h HEMA 52.912 (SAME)
EOEMA 05.727 IPA 37.00 EDMA 01.618 MAA 1.057 Vazo-52 0.336 Lupersol
256 0.331 BZT 1.0 0.75 0.5 0.5 0.5 0.75 0.75 1.0 BP* 0.5 0.5 0.5
0.5 -- 0.75 0.75 -- Methyl- -- -- -- 0.5 0.5 -- 0.75 1.0 BZT** %
H.sub.2O 49 51 50 49 50 48 47 48 Avg. % T 0.45 0.92 2.26 0.25 1.23
0.34 0.25 0.14 (280- 315 nm) Avg. % T 0.32 0.82 2.85 1.91 5.24 0.57
0.46 0.13 (316- 380 nm) *2-hydroxy-4-methacryloxy-benzophenone
**2-(2'-(4"-vinylbenzoxy)-5'-methylphenyl)-2H-benzotriazole
[0112] The solids content of these lenses are shown on a dry basis.
The hydrated lenses had a water content as shown in the table. The
lenses were made by placing the monomer formulation in to the
contact lens mold at 70.degree. C. for 30 minutes, then ramping up
to 120.degree. C. over 10 minutes and holding for 30 minutes. The
lenses were cooled down and cycled through an autoclave in saline
solution.
[0113] The UV transmission spectra for the lenses of Examples 5a
through 5h are shown in FIG. 1.
EXAMPLE 6(a-d)
[0114]
6 % Weight Ingredient 6a 6b 6c 6d MMA 29.88 NVP 69.34 AMA 0.15
(SAME) Vazo 64 0.89 BP 0.90 0.90 0.90 0.90 BZT 0.40 0.80 -- -- UVAM
-- -- 0.80 1.60 % H.sub.2O (after hydration) 77 76 72 68 Avg. % T
5.6 4.0 1.6 0.09 (280-315 nm) Avg. % T 17.5 9.2 9.3 0.54 (316-380
nm)
EXAMPLE 7 (a-f)
[0115] RGP lenses
7 % Weight Polymer Base Ingredient 7a 7b 7c 7d 7e 7f TPMD 40.00 MMA
54.77 MAA 5.00 (SAME) TEGDMA 0.10 TBPP 0.13 D&C Green #6
0.00715 Dye TINUVIN-326 0.06 0.75 0.50 0.75 0.82 0.90 MBP 0.15 --
0.15 0.15 -- -- Avg. % T 0.82 1.50 0.89 0.41 1.02 0.91 (280-315 nm)
Avg. % T 1.09 0.39 1.17 0.34 0.23 0.15 (316-380 nm)
[0116] A stock solution of the above polymer base ingredients was
prepared, and varying amounts of Tinuvin-326 and MBP were added to
separate portions of the polymer base to individually obtain
formulae 7a-7f. Rods were filled and warmed at 48.degree. C. for 24
hours; then cured at 110.degree. C. for 24 hours. The rods were
annealed by ramping the temperature to 110.degree. C. over 2 hours
and holding for 70 hours, then cooling over a 2 hour period. The
rods were irradiated with 1.0 mRad from a Co-60 source. The rods
were sliced into buttons and then machined and polished into 8 mm
diameter lenses. Five lenses for each UV absorber formulation,
Example 7a through 7f, were measured for UV absorption. The results
were averaged and listed above.
EXAMPLE No. 8
[0117] HEMA-based UV comparison
Example8(a)
[0118] A polymer base was prepared according to the following shown
on a total wet basis:
[0119] HEMA49.491%, EOEMA-4.97%, APM-0.08%, IPA-42.10%, EDMA-1.20%,
MAA-4.0590, Vazo 52-0.028%, BZT-0.82%. This amount of BZT added is
equivalent to 1.42% by weight of dry polymer. The resulting contact
lenses had average transmittance values of 6.8% for 280-315 nm
(UVB) and 2.1% for 316-380 nm (UVA). At 280 nm, the transmittance
was 18.72%, which is equivalent to 0.73 Absorbance units.
Example 8(b)
[0120] To the same polymer base as above 0.75% BZT and 0.79% BP on
a dry basis was added, for a total of 1.54% UV absorbers on a dry
weight basis. The resulting contact lenses had average
transmittance values of 1.03-% for 280-315 nm (UVB) and 4.07% for
316-380 nm (UVA). At 280 nm, the transmittance was 1.89%, which is
equivalent to 1.72 Absorbance units.
Comparison of Examples 8(a) and 8(b)
[0121] Based on the results of 8(a), one can calculate the amount
of BZT needed to obtain the same absorbance as was obtained in 8(b)
using a mixture of BZT and BP. Using Beer's Law, the following
equation is used % BZT (8a).times.Abs(8b)/Abs(8a)=% BZT. Plugging
in the numbers as follows: 1.42%.times.1.72/0.73 equals 3.35% BZT
on a dry basis is calculated to obtain 1.89% transmittance at
280nm. This is more than double the total amount by weight of
combined UV absorbers used in Ex. 8(b).
Example 8(c)
[0122] To the same polymer base as above 0.64% BZT and 0.1.39% BP
on a dry basis was added, for a total of 2.03% UV absorbers on a
dry weight basis. The resulting contact lenses had average
transmittance values of 0.15% for 280-315 nm (UVB) and 3.67% for
316-380 nm (UVA). At 280 nm, the transmittance was 0.249%, which is
equivalent to 2.62 Absorbance units.
Comparison of Examples 8(a) and 8(c)
[0123] Based on the results of 8(a), one can calculate the amount
of BZT needed to obtain the same absorbance as was obtained in 8(c)
using a mixture of BZT and BP. Again, using Beer's Law, one can
calculate the amount of BZT needed as follows:
1.42%.times.2.62/0.73 equals 5.10% BZT on a dry basis is calculated
to obtain 1.89% transmittance at 280 nm. This is more than 2.5
times the total amount by weight of combined UV absorbers used in
Ex. 8(c).
Example No. 9
[0124] DMA/MMA-based lenses Comparative Example
[0125] In this example, UV-blocking monomers, BP and BZT, were used
individually and in combination at the same levels to make molded
experimental RGP lenses. For comparison, the averaged percent
transmission data in the UVA and UVB range are reported below.
Target Formulations for Examples 9a and 9b
[0126]
8 UV DMA/MMA AIBN BP BZT Lens IMT Blocker Ratio IMT wt % wt % wt %
9a-1 D&C* BP 1.07:1 75 ppm 0.30 1.00 9b-1 D&C BZT 1:07:1 75
ppm 0.30 1.50 9a-2 APM** BP 1.07:1 75 ppm 0.30 1.00 9b-2 APM BZT
1.07:1 75 ppm 0.30 1.50 *D&C = D&C Green Number 6 **APM = A
dispersion of phthalocyanine green in DMA/MMA
Formulation Information for Example 9c
[0127]
9 Lens 9c-1 Lens 9c-2 Ingredient (Actual Wt. (g)) (Actual Wt. (g))
MMA 36.774 48.774 MMA/D + C 10.003 10 DMA 50.078 40.078 BP 1.001
1.003 BZT 1.505 1.506 AZBN 0.304 0.301 EGDMA 0.358 0.355
[0128] Lens Preparation
[0129] Lenses were filled on a LCCM type filler/sealer using hand
filling of cavities. Lenses were hydrated and processed as
follows:
[0130] Cure was carried out in a Gallenkamp oven as follows:
[0131] Nitrogen purge for 1 hour at ambient conditions
[0132] Ramp to 72.degree. C. at 45.degree. C. hour
[0133] Dwell at 72.degree. C. for one hour
[0134] Ramp to 124.degree. C. at 45.degree. C. hour
[0135] Dwell at 124.degree. C. for 48 minutes
[0136] Off
[0137] This polymerization is a thermal cure using AZBN (or AIBN,
Vazo 64, etc.). The lenses were hydrated after polymerization.
[0138] The UV/V spectra was run using a Perkin-Elmer
spectrophotometer fitted with an integrating sphere detector. The
percent transmissions of the different lens formulations were
averaged over the UVA and UVB region and listed in categories
according to UV monomer composition, as shown below.
10 UV Transmittance Comparison UV monomers(s) Ave % T Ave % T
Example (dry weight basis) (280-315 nm) (316-380 nm) 9a 1% BP 1.6
26.7 9b 1.5% BZT 4.7 7.7 9c 1% BP & 1.5% BZT 0.1 0.25
[0139] The data above show in a crisp way the benefit derived from
combining UV blockers. Besides the predictable "covering of holes"
in the UV spectrum, it is observed that an enhanced reduction in
percent transmission is obtained, greater than might have been
expected.
[0140] The invention has been described with reference to specific
embodiments, which are provided only for exemplification and are
not to be construed as limiting the scope of the invention as
defined by the appended claims.
* * * * *