Note: Descriptions are shown in the official language in which they were submitted.
CA 02391854 2005-O1-24
OPTICAL RESIN COI~OSITI~1
BACKGROnND OF THE INVENTION
1. Field of the Invention
The present invention relates to polymerizable organic
compositions and polymerizates obtained therefrom having a
refractive index of at least 1.6, an Abbe number of at least
33 and an initial Barcol hardness of at least 1. More
particularly, the present invention relates to certain
polymerizable organic compositions comprising a radically
polymerizable monomer having at least two (meth)acryloyl
groups and backbone linkages., selected from thiourethane
linkages and/or dithiourethane linkages. The present
invention also relates to photochromic articles prepared from
such polymerizable compositions.
2. Description of the Prior Art
A number of organic polymeric materials, e.g., plastics,
have been developed as alternatives and replacements for glass
in applications such as optical lenses, fiber optics, windows
and automotive, nautical and aviation transparencies. As used
herein, the term 'glass' is meant to refer to silica-based
inorganic glass. These polymeric materials can provide
advantages relative to glass, including, shatter resistance,
lighter weight for a given application, ease of molding and
ease of dying. Representative examples of such polymeric
materials include, poly(methyl methacrylate), thermoplastic
polycarbonate and poly[diethylene glycol bis(allylcarbonate)].
The refractive indices of many polymeric materials are
generally lower than that of glass. For example, the
refractive index of poly[diethylene glycol
bis(allylcarbonate)] is about 1.50, compared to that of high
index glass, which can range, for example, from 1.60 to 1.80.
When fabricating lenses to correct a given degree of visual
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-2-
defect, e.g., a correction for myopia, the use of a polymeric
material having a lower refractive index will require a
thicker lens relative to a material having a higher refractive
index, e.g., high index glass. If the degree of correction
required is substantial, as in the case of severe myopia, a
lens fabricated from a low index polymeric material can be
required to be very thick. A very thick lens may negate any
benefit of reduction in weight relative to an equivalent
degree of correction obtained from a higher refractive index
lens, e.g., a high index glass lens. In addition, thicker
optical lenses are not aesthetically desirable.
It is known that polymeric materials having refractive
indices greater than 1.50 can be prepared from aromatic
monomers and monomers containing halogens and/or sulfur atoms.
The materials from which-lenses, and in particular optical
lenses, are fabricated can be categorized by their refractive
indices. As is known to those of ordinary skill in the art,
low indices typically include indices of refraction of from
less than 1.50 through 1.53; middle indices comprise indices
of refraction of from 1.54 through 1.57; and high indices
commonly include indices of_refraction of 1.58 and greater.
Lenses prepared from polymeric materials having high
refractive indices typically also have lower Abbe numbers
(also known as nu-values). Lower Abbe numbers are indicative
of an increasing level of chromatic dispersion, which is
typically manifested as an optical distortion at or near the
rim of the lens.
U.S. Patent No. 5,384,379 to Bader et al. discloses
sulfur-containing poly(meth)acrylates for optical
applications. Although the materials disclosed by Bader et al.
can be used as lenses to provide optical corrections, the
poly(meth)acrylates disclosed generally provide an inadequate
refractive index and chromatic dispersion. They also,
generally, have poor impact resistance.
It is accordingly desirable then to identify new
polymerizable organic compositions, which can be used to
prepare transparent polymerizates, particularly optical
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-3-
lenses, that possess a combination of high refractive index
and adequately high Abbe numbers. It is further desirable
that these polymeric materials also possess physical
properties, and in particular thermal properties, that are at
S least equivalent to and preferably better than those of lower
index polymeric materials.
SiJMHIARY OF THE INVENTION
In accordance with the present invention, there is
provided a polymerizable organic composition comprising one or
more radically polymerizable monomers with at least one.
radically polymerizable monomer having at least two
(meth)acryloyl groups that have backbone linkages selected
from thiourethane linkages, dithiourethane linkages,
combinations of thiourethane linkages and dithiourethane
1S linkages.
The present invention is also directed to polymerizates
prepared from the polymerizable organic composition of the
present invention.
The present invention is further directed to shaped
articles prepared from the polymerizable compositions of the
present invention.
The present invention is yet further directed to
photochromic articles that may be prepared from the
polymerizable organic composition of the present invention.
2S DETAILED DESCRIPTION OF THE INVENTION
Unless otherwise indicated, all numbers or expressions
referring to quantities of ingredients, reaction conditions,
etc. used herein are to be understood as modified in all
instances by the term "about."
The present invention is directed to a polymerizable
organic composition comprising:
(a) a first radically polymerizable monomer having
at least two (meth)acryloyl groups, said first monomer having
backbone linkages selected from thiourethane linkages,
3S dithiourethane linkages, combinations of thiourethane linkages
and dithiourethane linkages, and optional backbone linkages
CA 02391854 2005-O1-24
selected from urethane linkages, urea linkages, thiocarbamate
linkages and combinations thereof:
(b) optionally a second radically polymerizable
monomer that is different than said first radically
S polymerizable monomer (a) and having at least two
ethylenically unsaturated radically polymerizable groups
selected from vinyl, allyl and (meth)acryloyl:
(c) optionally a third radically polymerizable
monomer having at least one ethylenically unsaturated
radically polymerizable group, which is different than monomer
(a) and monomer (b), selected from the group consisting of,
(i) a monoethylenically unsaturated monomer;
(ii) an anhydride monomer having at least one
ethylenically unsaturated group, which is different than
monomer (i): and
(iii) mixtures of monomers (i) and (ii); and
(d) optionally a polythiol monomer having at least
two thiol groups.
The present invention is also directed to a polymerizate
of the polymerizable organic composition, which has a
refractive index of from about 1.57 to about 1.80, preferably
about 1.60 to about 1.75: an Abbe number of at least about 30,
preferably at least about 33; and an initial Barcol hardness
of at least 1. In a most preferred~embodiment, the refractive
index will be at least 1.6 (e.g., from 1.60 to 1.74). The
refractive index is determined in accordance with American
Standard Test Method (ASTM) number D 542-95. The Abbe number
or nu-value is determined using an appropriate instrument, for
TM
example a Bausch ~ Lomb ABBE-3L Refractometer. The initial
Barcol hardness (also commonly referred to as a zero second
Barcol hardness) is determined in accordance with ASTM No. D
2583-95.
The first monomer (a) of the polymerizable composition
has backbone linkages selected from thiourethane linkages (-
NH-C(O)-S-), dithiourethane linkages (-NH-C(S)-S-) and
combinations thereof. In addition, the first monomer may also
optionally have backbone linkages selected from urethane
CA 02391854 2005-O1-24
-5-
linkages (-NH-C(O)-0-), urea linkages (e. g., unsubstituted
urea linkages -NH-C(O)-NH- andlor substituted urea linkages -
N (R1,) -C (0) -NH- where R14 may be a C1-C, alkyl group) ,
thiocarbamate linkages (-NH-C(S)-O-) and combinations thereof.
The first monomer is typically prepared in a two step
process in which a precursor which forms the backbone of the
first monomer is formed, followed by functionalization of the
terminal portions of the precursor with (meth)acryloyl groups.
The precursor of the first monomer is generally prepared from
the reaction of (1) a polythiol monomer having at least_two
thiol groups; (2) a polycyanate monomer having at least two
functional groups selected from isocyanate (-NCO),
isothiocyanate (-NCS) and combinations thereof: and (3)
optionally a reactive hydrogen material having at least two
reactive hydrogen groups selected from hydroxyl, primary
amine, secondary amine and combinations thereof. The thiol
groups of the polythiol monomer (1) typically comprise at
least 50 mole percent, e.g., at least 80 mole percent or at
least 90 mole percent, of the total molar equivalents of thiol
groups, hydroxyl groups, primary amine groups and secondary
amine groups of said polythiol monomer and said reactive
hydrogen material.
In the preparation of the precursor of the first monomer,
the molar equivalents ratio of (NCO + NCS)/(SH + OH + NH2 + -
NH-) is typically from'0.25 . 1 to 4 . 1, e.g., from 0.5 : 1
to 2 . 1 or from 0.8 . 1 to 1.2 . 1. Accordingly, the
precursor of the first monomer may have terminal cyanate
groups, e.g., isocyanate andlor isothiocyanate groups, or
terminal reactive hydrogen groups selected from
hydroxyl, primary amine, secondary amine, compounds having one or
more thiol and one or more hydroxyl groups, and combinations
thereof .
When the precursor of the first monomer has terminal
cyanate groups, the terminal portions of the precursor may be
functionalized by reaction with an alkyl (meth)acrylate having
reactive hydrogen functionality selected from hydroxyl, thiol
and primary amine. Typically the terminal cyanate portions of
the precursor are functionalized by reaction with a
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-6-
hydroxyalky (meth)acrylate, such as 2-hydroxyethyl
methacrylate. As used herein, by "(meth)acryloyl" and similar
terms, such as "(meth)acrylate," is meant to refer to acryloyl
groups, methacryloyl groups, and combinations of acryloyl
groups and methacryloyl groups. As used herein, the term
"cyanate," and similar terms, such as "polycyanate" and
"cyanate group(s)," refers to isocyanate groups (-NCO),
isothiocyanate groups (-NCS) and combinations of isocyanate
and isothiocyanate groups.
When the precursor of the first monomer has terminal
reactive hydrogen groups, e.g., terminal thiol groups, the
terminal portions of the precursor may be functionalized by
reaction with (meth)acrylic anhydride, (meth)acrylyl chloride
or a (meth)acrylate monomer having functionality that is
reactive with the terminal reactive hydrogen groups, for
example glycidyl (meth)acrylate, isocyanato alkyl
(meth)acrylate or hydroxy alkyl (meth)acrylate chloroformate
esters, an example of which is hydroxyethylmethacrylate
chloroformate ester.
The first monomer may be monomeric, oligomeric or
polymeric, and consequently may have a wide range of molecular
weights, for example, having a number average molecular weight
(Mn) of from 500 to 15,000, or from 500 to 5,000, as
determined by gel permeation chromatography using polystyrene
standards. Typically, the molecular weight of the first
monomer is selected such that the viscosity of the first
monomer is not too high for the application in which it is
used. For example, when used to prepare ophthalmic lenses,
the first monomer typically has a viscosity at 25°C of less
than 800 centipoise (cPs), e.g., less than 500 cPs.
The polythiol monomer used to prepare the precursor of
the first monomer has at least two thiol groups and may be
selected from 2,5-dimercaptomethyl-1,4-dithiane, 2,2'-
thiodiethanethiol, pentaerythritol tetrakis(3-
mercaptopropionate), pentaerythritol tetrakis(2-
mercaptoacetate), trimethylolpropane tris(3-
mercaptopropionate), trimethylolpropane tris(2-
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
mercaptoacetate), 4-mercaptomethyl-3,6-dithia-1,8-
octanedithiol, 4-tert-butyl-1,2-benzenedithiol, 4,4'-
thiodibenzenethiol, benzenedithiol, ethylene glycol di(2-
mercaptoacetate), ethylene glycol di(3-mercaptopropionate),
polyethylene glycol) di(2-mercaptoacetate), polyethylene
glycol) di(3-mercaptopropionate). Mixtures of polythiols may
be used to prepare the precursor of the first monomer.
A polythiol represented by the following general formula
I, may also be used to prepare the precursor of the first
monomer,
SH
(I) CH
2 I~
HS Rl C O C~CH2 O C RASH
wherein R1 and RZ are each independently selected from the
group consisting of straight or branched chain alkylene,
cyclic alkylene, phenylene and C1 - C9 alkyl substituted
phenylene, and mixtures of said polythiol monomers. Examples
of straight or branched chain alkylene from which Rl and RZ may
be selected include, but are not limited to, methylene,
ethylene, 1,3-propylene, 1,2-propylene, 1,4-butylene, 1,2-
butylene, pentylene, hexylene, heptylene, octylene, nonylene,
decylene, undecylene, octadecylene and icosylene. Examples of
cyclic alkylenes from which R1 and RZ may each be selected
include, but are not limited to, cyclopentylene,
cyclohexylene, cycloheptylene, cyclooctylene, and alkyl
substituted derivatives thereof. The divalent linking groups
R1 and Rz may also be selected from phenylene and alkyl
substituted phenylene, e.g., methyl, ethyl, propyl, isopropyl
and nonyl substituted phenylene. In a preferred embodiment of
the present invention, R1 and RZ are each methylene or
ethylene.
The polythiol represented by general formula I may be
prepared from an esterification or transesterification
reaction between 3-mercapto-1,2-propanediol (Chemical Abstract
Service (CAS) Registry No. 96-27-5) and a thiol functional
carboxylic acid or carboxylic acid ester in the presence of a
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
_g_
strong acid catalyst, e.g., methane sulfonic acid, with the
concurrent removal of water or alcohol from the reaction
mixture.
As used herein, the polythiol monomer described and named
with reference to general formula I, e.g., thioglycerol bis(2-
mercaptoacetate), is meant to include also any related co-
product oligomeric species and polythiol monomer compositions
containing residual starting materials. For example, when
washing the reaction mixture resulting from the esterification
of 3-mercapto-1,2-propanediol and a thiol functional
carboxylic acid, e.g., 2-mercaptoacetic acid, with excess
base, e.g., aqueous ammonia, oxidative coupling of thiol
groups may occur. Such an oxidative coupling can result in
the formation of oligomeric polythiol species having disulfide
linkages, i.e., -S-S- linkages.
The polythiol monomer used to prepare the precursor of
the first monomer may be a polythiol oligomer having disulfide
linkages, which is prepared from the reaction of a polythiol
monomer having at least two thiol groups and sulfur in the
presence of a basic catalyst. The molar equivalent ratio of
polythiol monomer to sulfur is from m to (m-1) wherein m is an
integer from 2 to 21. The polythiol monomer may be selected
from those examples as recited previously herein, e.g., 2,5-
dimercaptomethyl-1,4-dithiane. The sulfur used may be in the
form of, for example, crystalline, colloidal, powder and
sublimed sulfur, and having a purity of at least 98 percent
and preferably at least 99 percent.
Co-product oligomeric species can include oligomers of
general formula I which can be described by general formula
Ia:
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-9-
' $H
I a ~ ~Hz
S-R~ -C-O-CH-CHz-O-C-~z-S H
m
~Hz
S-Ri -C-O-CH-CHz-O-C~z-SH
~H ...
~Hz
S-R~ -C-O-CH-CHz-O-C-~z-S H
n
wherein R1 and Rz are as described above, n and m are
independently an integer from 0 to 21 and n + m is at least 1.
General formula Ia demonstrates that oligomerization can occur
through disulfide bonds forming between any of the thiol
groups in general structure I. Although all possibilities are
not shown, general structure II is meant to represent all
possible oligomers that can form from general structure I.
The basic catalyst used to prepare the polythiol oligomer
having disulfide linkages may be selected from ammonia, amine
and mixtures thereof. Examples of amines include, but are not
limited to alkylamines, e.g., ethylamine and n-butylamine,
dialkylamines, e.g., diethylamine, trialkylamines, e.g.,
triethylamine, morpholine, substituted morpholine, piperidine
and substituted piperidine. The basic catalyst is typically
present in an amount of from 0.001 to 1.0 mole percent, e.g.,
from 0.01 to 0.1 mole percent, based on the moles of polythiol
monomer present at the beginning of the reaction. The basic
catalyst may be charged together to a reaction vessel along
with the polythiol monomer and sulfur, or may be added to the
reaction vessel after the addition of the polythiol monomer
and sulfur.
Synthesis of the polythiol oligomer having disulfide
linkages may be conducted in the presence of a solvent, for
example, halogenated hydrocarbons, such as chloroform,
CA 02391854 2005-O1-24
-10-
aliphatic hydrocarbons, such as hexane, aromatic hydrocarbons,
such as toluene, and ethers, such as tetrahydrofuran. The
polythiol oligomer may be prepared at a temperature ranging
from room temperature to the boiling point of the solvent,
e.g., from room temperature to 120°C. The preparation of
polythiol oligomers having disulfide linkages that are useful
in the present invention is described in further detail in
United States Patent No. 5,961,889.
In an embodiment of the present invention, the polythiol
oligomer having disulfide linkages may be selected from those
represented by the following general formula II,
S
H-~--S
(II)
S
wherein y is an integer from 1 to 21. The polythiol aligomer
represented by general formula II may be prepared from the
reaction of 2,5-dimeracaptomethyl-1,4-dithiane with sulfur in
the presence of a basic catalyst, as described previously
herein.
The polycyanate monomer used to prepare the precursor of
the first monomer may be selected from polyisocyanates having
at least two isocyanate groups, isothiocyanates having at
least two isothiocyanate groups and polycyanates having both
isocyanate and isothiocyanate groups. Classes of
polyisocyanates from which the polycyanate monomer may be
selected include, but are not limited to: aliphatic
polyisocyanates: ethylenically unsaturated polyisocyanates;
alicyclic polyisocyanates: aromatic polyisocyanates wherein
the isocyanate groups are not bonded directly to the aromatic
ring, e.g., a,a'-xylene diisocyanate: aromatic polyisocyanates
wherein the isocyanate groups are bonded directly to the
aromatic ring, e.g., benzene diisocyanate: aliphatic
polyisocyanates containing sulfide linkages; aromatic
polyisocyanates containing sulfide or disulfide linkages
aromatic polyisocyanates containing sulfone linkages: sulfonic
ester-type polyisocyanates, e.g., 4-methyl-3-
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-11-
isocyanatobenzenesulfonyl-4'-isocyanato-phenol ester; aromatic
sulfonic amide-type polyisocyanates; sulfur-containing
heterocyclic polyisocyanates, e.g., thiophene-2,5-
diisocyanate; halogenated, alkylated, alkoxylated, nitrated,
carbodiimide modified, urea modified and biuret modified
derivatives of polyisocyanates belonging to these classes; and
dimerized and trimerized products of polyisocyanates belonging
to these classes. A particularly preferred sulfur containing
polycyanate monomer is one of general formula (III):
S ~~ Rt t ...
S~ NCO
(III) OCN ~
\ Rlo/- S
wherein Rlo and Rll are each independently C1 to C3 alkyl.
Examples of aliphatic polyisocyanates that may be used to
prepare the precursor of the first monomer include, but are
not limited to, ethylene diisocyanate, trimethylene
diisocyanate, tetramethylene diisocyanate, hexamethylene
diisocyanate, octamethylene diisocyanate, nonamethylene
diisocyanate, 2,2'-dimethylpentane diisocyanate, 2,2,4-
trimethylhexane diisocyanate, decamethylene diisocyanate,
2,4,4,-trimethylhexamethylene diisocyanate, 1,6,11-
undecanetriisocyanate, 1,3,6-hexamethylene triisocyanate, 1,8-
diisocyanato-4-(isocyanatomethyl)octane, 2,5,7-trimethyl-1,8-
diisocyanato-5-(isocyanatomethyl)octane, bis(isocyanatoethyl)-
carbonate, bis(isocyanatoethyl)ether, 2-isocyanatopropyl-2,6-
diisocyanatohexanoate, lysinediisocyanate methyl ester and
lysinetriisocyanate methyl ester.
Examples of ethylenically unsaturated polyisocyanates
include, but are not limited to, butene diisocyanate and 1,3-
butadiene-1,4-diisocyanate. Alicyclic polyisocyanates that
may be used to prepare the precursor of the first monomer may
be selected include, but are not limited to, isophorone
diisocyanate, cyclohexane diisocyanate, methylcyclohexane
diisocyanate, bis(isocyanatomethyl)cyclohexane,
bis(isocyanatocyclohexyl)methane, bis(isocyanatocyclohexyl)-
2,2-propane, bis(isocyanatocyclohexyl)-1,2-ethane, 2-
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-12-
isocyanatomethyl-3-(3-isocyanatopropyl)-5-isocyanatomethyl-
bicyclo[2.2.1]-heptane, 2-isocyanatomethyl-3-(3-
isocyanatopropyl)-6-isocyanatomethyl-bicyclo[2.2.1]-heptane,
2-isocyanatomethyl-2-(3-isocyanatopropyl)-5-isocyanatomethyl-
bicyclo[2.2.1]-heptane, 2-isocyanatomethyl-2-(3-
isocyanatopropyl)-6-isocyanatomethyl-bicyclo[2.2.1]-heptane,
2-isocyanatomethyl-3-(3-isocyanatopropyl)-6-(2-
isocyanatoethyl)-bicyclo[2.2.1]-heptane, 2-isocyanatomethyl-2-
(3-isocyanatopropyl)-5-(2-isocyanatoethyl)-bicyclo[2.2.1]-
heptane and 2-isocyanatomethyl-2-(3-isocyanatopropyl)-6-(2-
isocyanatoethyl)-bicyclo[2.2.1]-heptane.
Examples of aromatic polyisocyanates wherein the
isocyanate groups are not bonded directly to the aromatic ring
include, but are not limited to, bis(isocyanatoethyl)benzene,
a,a,a',a'-tetramethylxylene diisocyanate, 1,3-bis(1-
isocyanato-1-methylethyl)benzene, bis(isocyanatobutyl)benzene,
bis(isocyanatomethyl)naphthalene,
bis(isocyanatomethyl)diphenyl ether,
bis(isocyanatoethyl)phthalate, mesitylene triisocyanate and
2,5-di(isocyanatomethyl)furan. Examples of aromatic
polyisocyanates, having isocyanate groups bonded directly to
the aromatic ring, that may be used to prepare the first
monomer precursor, include, but are not limited to, phenylene
diisocyanate, ethylphenylene diisocyanate, isopropylphenylene
diisocyanate, dimethylphenylene diisocyanate, diethylphenylene
diisocyanate, diisopropylphenylene diisocyanate,
trimethylbenzene triisocyanate, benzene triisocyanate,
naphthalene diisocyanate, methylnaphthalene diisocyanate,
biphenyl diisocyanate, ortho-tolidine diisocyanate, 4,4'-
diphenylmethane diisocyanate, bis(3-methyl-4-
isocyanatophenyl)methane, bis(isocyanatophenyl)ethylene, 3,3'-
dimethoxy-biphenyl-4,4'-diisocyanate, triphenylmethane
triisocyanate, polymeric 4,4'-diphenylmethane diisocyanate,
naphthalene triisocyanate, diphenylmethane-2,4,4'-
triisocyanate, 4-methyldiphenylmethane-3,5,2',4',6'-
pentaisocyanate, diphenylether diisocyanate,
bis(isocyanatophenylether)ethyleneglycol,
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-13-
bis(isocyanatophenylether)-1,3-propyleneglycol, benzophenorie
diisocyanate, carbazole diisocyanate, ethylcarbazole
diisocyanate and dichlorocarbazole diisocyanate.
Aliphatic polyisocyanates containing sulfide linkages
that may be used to prepare the first monomer precursor may be
selected from, for example, thiodiethyl diisocyanate,
thiodipropyl diisocyanate, dithiodihexyl diisocyanate,
dimethylsulfone diisocyanate, dithiodimethyl diisocyanate,
dithiodiethyl diisocyanate, dithiodipropyl diisocyanate and
dicyclohexylsulfide-4,4'-diisocyanate. Examples of aromatic
polyisocyanates containing sulfide or disulfide linkages
include, but are not limited to, diphenylsulfide-2,4'-
diisocyanate, diphenylsulfide-4,4'-diisocyanate, 3,3'-
dimethoxy-4,4'-diisocyanatodibenzyl thioether, bis(4-
isocyanatomethylbenzene)-sulfide, diphenyldisulfide-4,4'-
diisocyanate, 2,2'-dimethyldiphenyldisulfide-5,5'-
diisocyanate, 3,3'-dimethyldiphenyldisulfide-5,5'-
diisocyanate, 3,3'-dimethyldiphenyldisulfide-6,6'-
diisocyanate, 4,4'-dimethyldiphenyldisulfide-5,5'-
diisocyanate, 3,3'-dimethoxydiphenyldisulfide-4,4'-
diisocyanate and 4,4'-dimethoxydiphenyldisulfide-3,3'-
diisocyanate.
Aromatic polyisocyanates containing sulfone linkages that
may be used to prepare the first monomer precursor may be
selected from, for example, diphenylsulfone-4,4'-diisocyanate,
diphenylsulfone-3,3'-diisocyanate, benzidinesulfone-4,4'-
diisocyanate, diphenylmethanesulfone-4,4'-diisocyanate, 4-
methyldiphenylmethanesulfone-2,4'-diisocyanate, 4,4'-
dimethoxydiphenylsulfone-3,3'-diisocyanate, 3,3'-dimethoxy-
4,4'-diisocyanatodibenzylsulfone, 4,4'-
dimethyldiphenylsulfone-3,3'-diisocyanate, 4,4'-di-tert-butyl-
diphenylsulfone-3,3'-diisocyanate and 4,4'-
dichlorodiphenylsulfone-3,3'-diisocyanate.
Examples of aromatic sulfonic amide-type polyisocyanates
that may be used to prepare first monomer precursor include,
but are not limited to, 4-methyl-3-isocyanato-benzene-
sulfonylanilide-3'-methyl-4'-isocyanate, dibenzenesulfonyl-
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-14-
ethylenediamine-4,4'-diisocyanate, 4,4'-
methoxybenzenesulfonyl-ethylenediamine-3,3'-diisocyanate and
4-methyl-3-isocyanato-benzene-sulfonylanilide-4-ethyl-3'-
isocyanate.
Classes of polyisothiocyanates that may be used to
prepare the first monomer precursor include, but are not
limited to: aliphatic polyisothiocyanates: alicyclic
polyisothiocyanates, e.g., cyclohexane diisothiocyanates;
aromatic polyisothiocyanates wherein the isothiocyanate groups
are not bonded directly to the aromatic ring, e..g., a,a_'-
xylene diisothiocyanate; aromatic polyisothiocyanates wherein
the isothiocyanate groups are bonded directly to the aromatic
ring, e.g., phenylene diisothiocyanate; heterocyclic
polyisothiocyanates, e.g., 2,4,6-triisothicyanato-1,3,5-
triazine and thiophene-2,5-diisothiocyanate; carbonyl
polyisothiocyanates; aliphatic polyisothiocyanates containing
sulfide linkages, e.g., thiobis(3-isothiocyanatopropane);
aromatic polyisothiocyanates containing sulfur atoms in
addition to those of the isothiocyanate groups; halogenated,
alkylated, alkoxylated, nitrated, carbodiimide modified, urea
modified and biuret modified derivatives of
polyisothiocyanates belonging to these classes; and dimerized
and trimerized products of polyisothiocyanates belonging to
these classes.
Examples of aliphatic polyisothiocyanates that may be
used to prepare the first monomer precursor include, but are
not limited to, 1,2-diisothiocyanatoethane, 1,3-
diisothiocyanatopropane, 1,4-diisothiocyanatobutane and 1,6-
diisothiocyanatohexane. Examples of aromatic
polyisothiocyanates having isothiocyanate groups bonded
directly to the aromatic ring include, but are not limited to,
1,2-diisothiocyanatobenzene, 1,3-diisothiocyanatobenzene, 1,4-
diisothiocyanatobenzene, 2,4-diisothiocyanatotoluene, 2,5-
diisothiocyanato-m-xylene, 4,4'-diisothiocyanato-1,1'-
biphenyl, l,1'-methylenebis(4-isothiocyanatobenzene), 1,1'-
methylenebis(4-isothiocyanato-2-methylbenzene), 1,1'-
methylenebis(4-isothiocyanato-3-methylbenzene), 1,1'-(1,2-
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-15-
ethane-diyl)bis(4-isothiocyanatobenzene), 4,4'-
diisothiocyanatobenzophenenone, 4,4'-diisothiocyanato-3,3'-
dimethylbenzophenone, benzanilide-3,4'-diisothiocyanate,
diphenylether-4,4'-diisothiocyanate and diphenylamine-4,4'-
diisothiocyanate.
Carbonyl polyisothiocyanates that may be used to prepare
the first monomer precursor include, but are not limited to,
hexane-dioyl diisothiocyanate, nonaedioyl diisothiocyanate,
carbonic diisothiocyanate, 1,3-benzenedicarbonyl
diisothiocyante, 1,4-benzenedicarbonyl diisothiocyanate..and
(2,2'-bipyridine)-4,4'-dicarbonyl diisothiocyanate. Examples
of aromatic polyisothiocyanates containing sulfur atoms in
addition to those of the isothiocyanate groups, that may be
used to prepare the first monomer precursor include, but are
not limited to, 1-isothiocyanato-4-[(2-
isothiocyanato)sulfonyl]benzene, thiobis(4-
isothiocyanatobenzene), sulfonylbis(4-isothiocyanatobenzene) ,
sulfinylbis(4-isothiocyanatobenzene), dithiobis(4-
isothiocyanatobenzene), 4-isothiocyanato-1-[(4-
isothiocyanatophenyl)-sulfonyl]-2-methoxybenzene, 4-methyl-3-
isothicyanatobenzene-sulfonyl-4'-isothiocyanate phenyl ester
and 4-methyl-3-isothiocyanatobenzene-sulfonylanilide-3'-
methyl-4'-isothiocyanate.
The polycyanate monomer used to prepare the first monomer
precursor may also be selected from polycyanate monomers
having both isocyanate and isothiocyanate groups, which may
be, for example, aliphatic, alicyclic, aromatic, heterocyclic,
or contain sulfur atoms in addition to those of the
isothiocyanate groups. Examples of such compounds, include,
but are not limited to, 1-isocyanato-3-isothiocyanatopropane,
1-isocanato-5-isothiocyanatopentane, 1-isocyanato-6-
isothiocyanatohexane, isocyanatocarbonyl isothiocyanate, 1-
isocyanato-4-isothiocyanatocyclohexane, 1-isocyanato-4-
isothiocyanatobenzene, 4-methyl-3-isocyanato-1-
isothiocyanatobenzene, 2-isocyanato-4,6-diisothiocyanato-
1,3,5-triazine, 4-isocyanato-4'-isothiocyanato-diphenyl
sulfide and 2-isocyanato-2'-isothiocyanatodiethyl disulfide.
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-16-
A reactive hydrogen material having at least two reactive
hydrogen groups may optionally be used to prepare the
precursor of the first monomer. The reactive hydrogen
material may be selected from polyols, polyamines having at
least two primary amine and/or secondary amine groups, and
materials having both hydroxyl and amine functionality. As
used herein, by "reactive hydrogen material" is meant a
material having reactive hydrogen groups that are capable of
forming covalent bonds with isocyanate and isothiocyanate
groups.
Classes of polyols that may be used to prepare the
precursor of the first monomer, include, but are not limited
to: straight or branched chain alkane polyols, e.g., 1,2-
ethanediol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol,
1,3-butanediol, glycerol, neopentyl glycol, trimethylolethane,
trimethylolpropane, di-trimethylol propane, erythritol,
pentaerythritol and di-pentaerythritol; polyalkylene glycols,
e.g., diethylene glycol, dipropylene glycol and higher
polyalkylene glycols such as polyethylene glycols having
number average molecular weights of, for example, from 200 to
2000 grams / mole; cyclic alkane polyols, e.g.,
cyclopentanediol, cyclohexanediol, cyclohexanetriol,
cyclohexanedimethanol, hydroxypropylcyclohexanol and
cyclohexanediethanol; aromatic polyols, e.g.,
dihydroxybenzene, benzenetriol, hydroxybenzyl alcohol and
dihydroxytoluene; bisphenols, e.g., 4,4'-
isopropylidenediphenol; 4,4'-oxybisphenol, 4,4'-
dihydroxybenzophenone, 4,4'-thiobisphenol, phenolphthlalein,
bis(4-hydroxyphenyl)methane, 4,4'-(1,2-ethenediyl)bisphenol
and 4,4'-sulfonylbisphenol; halogenated bisphenols, e.g.,
4,4'-isopropylidenebis(2,6-dibromophenol), 4,4'-
isopropylidenebis(2,6-dichlorophenol) and 4,4'-
isopropylidenebis(2,3,5,6-tetrachlorophenol); alkoxylated
bisphenols, e.g., alkoxylated 4,4'-isopropylidenediphenol
having from 1 to 70 alkoxy groups, for example, ethoxy,
propoxy, a-butoxy and (3-butoxy groups; and biscyclohexanols,
which can be prepared by hydrogenating the corresponding
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-17-
bisphenols, e.g., 4,4'-isopropylidene-biscyclohexanol, 4,4'-
oxybiscyclohexanol, 4,4'-thiobiscyclohexanol and bis(4-
hydroxycyclohexanol)methane.
Compounds containing one or more hydroxy and one or more
thiol groups may be used to prepare the precursor of the first
monomer. Examples of materials having both hydroxyl and thiol
groups include, but are not limited to, 2-mercaptoethanol, 3-
mercapto-1,2-propanediol, glycerin bis(2-mercaptoacetate),
glycerin bis(3-mercaptopropionate), 1-hydroxy-4-
mercaptocyclohexane, 2,4-dimercaptophenol, 2-
mercaptohydroquinone, 4-mercaptophenol, 1,3-dimercapto-2-
propanol, 2,3-dimercapto-1-propanol, 1,2-dimercapto-1,3-
butanediol, trimethylolpropane bis(2-mercaptoacetate),
trimethylolpropane bis(3-mercaptopropionate), pentaerythritol
mono(2-mercaptoacetate), pentaerythritol bis(2-
mercaptoacetate), pentaerythritol tris(2-mercaptoacetate),
pentaerythritol mono(3-mercaptopropionate), pentaerythritol
bis(3-mercaptopropionate), pentaerythritol tris(3-
mercaptopropionate), hydroxymethyl-
tris(mercaptoethylthiomethyl)methane, 1-hydroxyethylthio-3-
mercaptoethylthiobenzene, 4-hydroxy-4'-
mercaptodiphenylsulfone, dihydroxyethyl sulfide mono(3-
mercaptopropionate and hydroxyethylthiomethyl-
tris(mercaptoethylthio)methane.
Polyamines that may be optionally used to prepare the
first monomer precursor have at least two functional groups
selected from primary amine (-NHz), secondary amine (-NH-) and
combinations thereof. Preferably the optional polyamine has
at least two primary amine groups.
The polyamine that may be used to prepare the first
monomer precursor may be selected from any of the family of
ethyleneamines, e.g., ethylenediamine (EDA),
diethylenetriamine (DETA), triethylenetetramine (TETA),
tetraethylenepentamine (TEPA), pentaethylenehexamine (PEHA),
piperazine, i.e., diethylenediamine (DEDA), and 2-amino-1-
ethylpiperazine. The optional polyamine may also be selected
from one or more isomers of C1-C3 dialkyl toluenediamine, such
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-18-
as, 3,5-dimethyl-2,4-toluenediamine, 3,5-dimethyl-2,6-
toluenediamine, 3,5-diethyl-2,4-toluenediamine, 3,5-diethyl-
2,6-toluenediamine, 3,5-diisopropyl-2,4-toluenediamine, 3,5-
diisopropyl-2,6-toluenediamine and mixtures thereof.
Additional example of polyamines that may be used to prepare
the first monomer precursor include, but are not limited to
methylene dianiline and trimethyleneglycol di(para-
aminobenzoate).
In an embodiment of the present invention, the optional
polyamine reactant can generally be described as.having_one of
the following general structures (IV-VI):
H2N NH2
(IV) U U
H2N NH2
(V)
S
H2N NH2
(VI)
Particularly preferred structures include one or more diamines
represented by the following general formulas VII-XX,
NH2
(VII)
~4
H2r
(VIII)
~5
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-19-
Ra
(IX)
~s
R3
(x)
~1H2
R3
(XI)
'~H2
(XII) \ /
Rs / S \ Rs
H2T NH2
~a
NH2
HZT Ra
(XIV)
\ Rs
Rs
(xv)
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-20-
s
H2r R3
'NH2
NH3 s
R3
(XVI)
Rs / S \ NH2 . _
Ks H4
( xV z I ) NH O O NH2
~s 1~ \~
( XV I I I ) NHOOOOoo-
Ra Rs Rs . Rs
3
(XIX) R4 O O
Rs ~s ~ Rs
) R3 o~---C
NH2 R4 Rs ~Rs
wherein R3 and RQ are each independently C1-C3 alkyl, and RS is
selected from hydrogen and halogen, e.g., chlorine and
bromine. The diamine represented by general formula VII can be
described generally as a 4,4'-methylene-bis(dialkylaniline).
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-21-
Specific examples of diamines represented by general formula
VII include, but are not limited to, 4,4'-methylene-bis(2,6-
dimethylaniline), 4,4'-methylene-bis(2,6-diethylaniline),
4,4'-methylene-bis(2-ethyl-6-methylaniline), 4,4'-methylene-
bis(2,6-diisopropylaniline), 4,4'-methylene-bis(2-isopropyl-6-
methylaniline) and 4,4'-methylene-bis(2,6-diethyl-3-
chloroaniline). A preferred diamine represented by general
formula VII is 4,4'-methylene-bis(2,6-diethyl-3-
chloroaniline).
~ In another embodiment of the present invention, the
polyamine reactant can generally be a 2,6 diamino toluene 3,5
dialkyl sulfide having the following general structures XXI:
H2N NH2
(XXI)
R6S~ ~ ~SR~
wherein R6 and R~ are linear, branched or cyclic C , to CZo
alkyl. Preferred compounds of general structure XXI are 2,6
diamino toluene 3,5 dimethyl sulfide and 2,6 diamino toluene
3,5 diethyl sulfide.
The diamine represented by general formula VII can be
described generally as a 4,4'-methylene-bis(dialkylaniline).
Specific examples of diamines represented by general formula
VII include, but are not limited to, 4,4'-methylene-bis(2,6-
dimethylaniline), 4,4'-methylene-bis(2,6-diethylaniline),
4,4'-methylene-bis(2-ethyl-6-methylaniline), 4,4'-methylene-
bis(2,6-diisopropylaniline), 4,4'-methylene-bis(2-isopropyl-6-
methylaniline) and 4,4'-methylene-bis(2,6-diethyl-3-
chloroaniline). A preferred diamine represented by general
formula VII is 4,4'-methylene-bis(2,6-diethyl-3-
chloroaniline).
The precursor of the first monomer may be prepared in the
presence of a catalyst. Catalysts that may be used in the
preparation of the first monomer precursor include, for
example, tertiary amines, e.g., triethylamine,
triisopropylamine and N,N-dimethylbenzylamine, and
organometallic compounds, e.g., dibutyltin dilaurate,
CA 02391854 2005-O1-24
-22-
dibutyltin diacetate and stannous octoate. Additional
examples of tertiary amines are listed in United States Patent
No. 5,693,738 at column 10 lines 6 through 38, the disclosure
of which is incorporated herein by reference. Additional
examples of organometallic compounds useful as catalysts are
listed in United States Patent No. 5,631,339 at column 4,
lines 26 through 46.
Catalyst levels are typically less than
5 % by weight, preferably less than 3 % by weight and more
preferably less than 1 % by weight, based on the. total weight
of the polythiol monomer, polycyanate monomer and optiona l
reactive hydrogen material.
The polymerizable composition of the present invention,
may optionally comprise a second radically polymerizable
IS monomer that is different that the first radically
polymerizable monomer. The second monomer has radically
polymerizable groups selected from vinyl, allyl and
(meth)acryloyl.
In an embodiment of the present invention, the second
monomer is an aromatic monomer having at least two vinyl
groups. Examples of aromatic monomers that may be used in the
polymerizable organic compositions of the present invention
include, but are not limited to: divinyl benzene, e:g., 1,2-
divinyl benzene, 1,3-divinyl benzene, 1,4-divinyl benzene and
mixtures of structural isomers of divinyl benzene:
diisopropenyl benzene, e.g., 1,2-diisopropenyl benzene, 1,3-
diisopropenyl benzene, 1,4-diisopropenyl benzene and mixtures
of structural isomers of diisopropenyl benzene: trivinyl
benzene, e.g., 1,2,4-triethenyl benzene, 1,3,5-triethenyl
benzene and mixtures of structural isomers of trivinyl
benzene; divinyl naphthalene, e.g., 2,6-diethenyl naphthalene,
1,7-diethenyl naphthalene, 1,4-diethenyl naphthalene and
mixtures of structural isomers of divinyl naphthalene: halogen
substituted derivatives of divinyl benzene, diisopropenyl
benzene, trivinyl benzene and divinyl naphthalene, e.g., 2-
chloro-1,4-diethenyl benzene: and mixtures of such aromatic
CA 02391854 2005-O1-24
-23-
monomers. In a preferred embodiment of the present invention,
the aromatic monomer is divinyl benzene.
In another embodiment of the present invention, the
second radically polymerizable monomer (b) having at least two
ethylenically unsaturated groups has (meth)acryloyl groups and
is selected from:
(i) a monomer represented by the following general
formula XXII,
(XXII)
HZC ~ O-CH-CHi O A-O HZ-CH-O =CHi
n
3 ~s
wherein m and n are each zero or a positive number, the sum of m
and n being from 0 to 70, preferably 2 to 40, and more preferably
5 to 2 0 , R3 and R4 are each hydrogen or methyl , RS and R6 are each
hydrogen or C1 to Cz alkyl, and A is a divalent linking group
selected from the group consisting of straight or branched chain
i5 alkylene (usually containing from 1 to 8 carbon atoms), cyclic
alkylene (usually being 5 to 8 carbon atoms), phenylene, C1 - C9
alkyl substituted phenylene, and a group represented by the
following general formula XXIII,
wherein, R~ and R8 are each C1 - C4 alkyl, chlorine or bromine,
7~p ~8~q
(XXIII) Z X Z
Z
p and q are each an integer from 0 to 4, represents a
divalent benzene group or a divalent cyclohexane group and X
i s O, S , -S ( OZ ) -, -C ( 0 ) -, -CHZ-, -CH=CH-, -C ( CH3 ) 2=.
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-24-
O
\ Z
O
-C (CH3) (C6H5) - or when is the divalent
Z
benzene group, and X is O, S, -CHz-, or -C(CH3)2- when
is the divalent cyclohexane group;
(ii) a bis[(meth)acryloyl-terminatedJpoly(ethylene
glycol) monomer, that is different than monomer (i), having a
number average molecular weight from 200 to 2,000 grams /
mole; and
(iii) a poly(meth)acryloyl terminated monomer represented
by the following general formula XXIV,
(xxlv) R' O-~CH2 CH O~-C C CH2
~5 d ~9
wherein R' is a polyvalent radical of a polyol, R9 is hydrogen
or methyl, RS is hydrogen or C1 to Cz alkyl, d is a number from
0 to 20, and j is a whole number from 3 to 6, preferably 3 to
4 and more preferably 3~. and
(iv) mixtures of monomers selected from the monomers
(i) , (ii) and (iii) .
The polymerizable second monomer (i) represented by
general formula IV may be prepared by methods that are well
known in the art. One such commonly used method involves a
two-step process, when the sum of m and n is greater than 0.
In the first step, a polyol, e.g., 4,4'-
isopropylidenediphenol, is reacted with an oxirane containing
substance, for example ethylene oxide, propylene oxide, a-
butylene oxide or (3-butylene oxide, to form what is commonly
referred to as an ethoxylated, propoxylated or butoxylated
polyol having hydroxy functionality. In the second step, the
ethoxylated, propoxylated or butoxylated polyol is esterified,
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-25-
or transesterified, with an alpha - beta unsaturated acid or
ester such as methacrylic acid, a C1 to C6 alkyl methacrylate,
an acrylic acid, a C1 to C6 alkyl acrylate, or a combination
thereof. The second step results in the formation of the
radically polymerizable monomer represented by general formula
IV. When the sum of m and n is 0, monomer (i) may be prepared
by esterifiying or transesterfying a polyol, e.g., 4,4'-
isopropylidenediphenol, with an alpha - beta unsaturated acid
or ester such as methacrylic acid, a C1 to C6 alkyl
methacrylate, an acrylic acid, a C1 to C6 alkyl acrylate, or a
combination thereof.
Examples of polyols suitable for use in preparing second
monomer (i) represented by general formula IV, include, but
are not limited to: straight chain alkylene glycols such as
ethylene glycol, propylene glycol, trimethylene glycol,
tetramethylene glycol, or diethylene glycol, triethylene
glycol; branched chain alkylene glycols such as 1,2-
propanediol, 2-methyl-1,3-propanediol, 1,2-butanediol, 1,3-
butanediol, 2,3-butanediol; cyclic alkylene diols such as 1,2-
cyclohexanediol, 1,3-cycl-ohexanediol and 1,4-cyclohexanediol;
phenylene diols such as ortho, meta and para dihydroxy
benzene; alkyl substituted phenylene diols such as 2,6-
dihydroxytoluene, 3-methylcatechol, 4-methylcatechol, 2-
hydroxybenzyl alcohol, 3-hydroxybenzyl alcohol, and 4-
hydroxybenzyl alcohol; dihydroxybiphenyls such as 4,4'-
dihydroxybiphenyl and 2,2'-dihydroxybiphenyl; bisphenols such
as 4,4'-isopropylidenediphenol; 4,4'-oxybisphenol; 4,4'-
dihydroxybenzophenone; 4,4'-thiobisphenol; phenolphthalein;
bis(4-hydroxyphenyl)methane; 4,4'-(1,2-ethenediyl)bisphenol;
and 4,4'-sulfonylbisphenol; halogenated bisphenols such as
4,4'-isopropylidenebis(2,6-dibromophenol), 4,4'-
isopropylidenebis(2,6-dichlorophenol) and 4,4'-
isopropylidenebis(2,3,5,6-tetrachlorophenol); and
biscyclohexanols, which can be prepared by hydrogenating the
corresponding bisphenols, such as 4,4'-isopropylidene-
biscyclohexanol; 4,4'-oxybiscyclohexanol; 4,4'-
thiobiscyclohexanol; and bis(4-hydroxycyclohexanol)methane.
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-26-
In a preferred embodiment of the present invention, with
reference to general formulas IV and V, X is -C(CH3)2-,
Z
represents a divalent benzene group, p and q are each
0, R3 and R9 are each methyl, RS and R6 are each hydrogen, and
the sum of m and n is from 5 to 20.
Polymerizable second monomer (ii) is different than
second monomer (i) and can be prepared as is known in the art
from an esterification or transesterification reaction between
polyethylene glycol) and an alpha - beta unsaturated acid or
ester such as methacrylic acid, a C1 to C6 alkyl methacrylate,
acrylic acid, a C1 to C6 alkyl acrylate, or a combination
thereof. The bis[(meth)acryloyl-terminated]poly(ethylene
glycol) monomer, preferably has a number average molecular
weight from 200 to 1200, more preferably from 500 to 700,
grams / mole, as determined by gel permeation chromatography
using a polystyrene standard. A particularly preferred second
monomer (ii) is a bismethacrylate of polyethylene glycol,
having a number average molecular weight of 600 grams / mole.
Polymerizable second monomer (iii), as previously
described with reference to general formula VI, may be
prepared by methods that are well known in the art. One such
commonly used method involves a two step process, when d is
greater than 0. In the first step, a-polyol, e.g.,
trimethylolpropane, is reacted with an oxirane containing
substance, for example ethylene oxide, propylene oxide, a-
butylene oxide or (3-butylene oxide to form what is commonly
referred to as an ethoxylated, propoxylated or butoxylated
polyol having hydroxy functionality. In the second step, the
ethoxylated, propoxylated or butoxylated polyol is esterified,
or transesterified, with an alpha - beta unsaturated acid or
ester such as methacrylic acid, a C1 to C6 alkyl methacrylate,
acrylic acid, a C1 to C6 alkyl acrylate, or a combination
thereof. The second step results in the formation of
polymerizable second monomer (iii). When d is 0, second
monomer (iii) may be prepared by esterifiying or
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-27-
transesterfying a polyol, e.g., trimethylolpropane, with an
alpha - beta unsaturated acid or ester such as methacrylic
acid, a C1 to C6 alkyl methacrylate, an acrylic acid, a C1 to C6
alkyl acrylate, or a combination thereof.
Examples of polyols suitable for use in preparing
polymerizable second monomer (iii) include, but are not
limited to, glycerol, trimethylolpropane, 1,3,5-tris(2-
hydroxyethyl)isocyanurate, di-trimethylolpropane,
pentaerythritol and dipentaerythritol. A particularly
preferred polymerizable second monomer (iii) may, be defined
with reference to general formula VI, wherein R' is a radical
of pentaerythritol, d is 0, j is 3 or 4 and R9 is hydrogen.
As used herein, and with reference to general formula VI,
the phrase "R' is a polyvalent radical of a polyol" is meant
to refer to the polyvalent residue of the polyol used in
preparing polymerizable second monomer (iii). For example, in
the case of pentaerythritol tetraacrylate (for which d is 0, j
is four and R9 is hydrogen), R' is the tetravalent radical of
pentaerythritol, i.e., tetramethylenemethane. In the case of
trimethylolpropane triacrylate (for which d is 0, j is 3 and R9
is hydrogen) R' is the trivalent radical of
trimethylolpropane, i.e., 1,1,1-trimethylenepropane.
In a further embodiment of the present invention, the
polymerizable second monomer having two or more ethylenically
unsaturated groups has allyl groups and is represented by the
following general formula XXV,
(XXV) R- [-O-C (O) -O-Rlo] i
wherein R is a radical derived from a polyol, Rlo is a radical
derived from an allyl or substituted allyl group and i is a
whole number from 2 to 6.
The polymerizable second monomer represented by general
formula XXV, may be further described as a polyol(allyl
carbonate) monomer. Polyol(allyl carbonate) monomers that may
be used in the aforedescribed polymerizable organic
composition are allyl carbonates of linear or branched
aliphatic or aromatic liquid polyols, e.g., aliphatic glycol
bis(allyl carbonate) compounds and alkylidene bisphenol
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-28-
bis(allyl carbonate) compounds. These monomers may also be
described as unsaturated polycarbonates of polyols, e.g.,
glycols and bisphenols. The polyol(allyl carbonate) monomer
may be prepared by procedures well known in the art, e.g., as
described in U.S. Patents 2,370,567 and 2,403,113.
In reference to general formula XXV, Rlo is a radical
derived from an allyl group which may be substituted at the 2-
position with a halogen, most notably chlorine or bromine, or
an alkyl group containing from 1 to 4, e.g., 1 to 2, carbon
atoms. Generally, the alkyl substituent is methyl or ethyl.
The Rlo radical may be represented by the following general
formula XXVI:
(XXVI ) HzC=C ( Ril ) -CHz-
wherein Rll is hydrogen, halogen or a C1 to C9 alkyl group.
Most commonly, Rll is hydrogen and consequently Rlo is the
unsubstituted allyl group, HZC=CH-CHZ- .
In reference to general formula XXV, R is a polyvalent
radical derived from a polyol which can be an aliphatic,
cycloaliphatic or an aromatic polyol containing 2, 3, 4, 5 or
6 hydroxy groups. Typically, the polyol contains 2 hydroxy
groups, i.e., a glycol or bisphenol. The aliphatic polyol may
be linear or branched and contain from 2 to 10 carbon atoms.
Commonly, the aliphatic polyol is an alkylene glycol having
from 2 to 4 carbons atoms, ethylene glycol, propylene glycol,
trimethylene glycol, tetramethylene glycol, or a poly(CZ - C9)
alkylene glycol, e.g., diethylene glycol, triethylene glycol,
etc. Other useful polyols include aromatic polyols such as
bisphenols, e.g., 4,4'-isopropylidenediphenol, and
cycloaliphatic polyols such as biscyclohexanols, e.g., 4,4'-
isopropylidenebiscyclohexanol.
Specific examples of polyol(allyl carbonate) monomers
that may be used in the polymerizable organic compositions of
the present invention, include, but are not limited to,
ethylene glycol bis(2-chloroallyl carbonate), ethylene glycol
bis(allyl carbonate), diethylene glycol bis(2-methylallyl
carbonate), diethylene glycol bis(allyl carbonate),
triethylene glycol bis(allyl carbonate), propylene glycol
CA 02391854 2005-O1-24
-29-
bis(2-ethylallyl carbonate), 1,3-propanediol bis(allyl
carbonate), 1,3-butanediol bis(allyl carbonate), 1,4
butanediol bis(2-bromoallyl carbonate), dipropylene glycol
bis(allyl carbonate), trimethylene glycol bis(2-ethylallyl
carbonate), pentamethylene glycol bis(allyl carbonate), 9,4'-
isopropylidenediphenol bis(allyl carbonate), and 4,4'-
isopropylidenebiscyclohexanol bis(allyl carbonate). A
preferred polyol(allyl carbonate) monomer is 4,4'-
isopropylidenediphenol bis(allyl carbonate).
A more detailed description of polyol(allyl carbonate)
monomers suitable for use in the present invention is found in
U.S. Patent 4,637,698 at column 3, line 33 through column 5,
line 61.
As used in the present description
with reference to general formula VII, the term polyol(allyl
carbonate) monomer or like names, e.g., diethylene glycol
bis(allyl carbonate), is intended to mean and include the
named monomers or prepolymers thereof and any related monomer
or oligomer species found with said monomer as a consequence
of the process used to synthesize the monomer.
The polymerizable composition of the present invention,
may optionally further comprise a third radically
polymerizable monomer that is different than the first and
second radically polymerizable monomers. The third radically
polymerizable monomer may be selected from monoethylenically
unsaturated monomers. Examples of such monoethylenically
unsaturated monomers include, but are not limited to, acrylic
acid, methacrylic acid, esters of acrylic acid such as methyl
or ethyl acrylate and 2-hydroxyethyl acrylate, esters of
methacrylic acid, such as methyl or ethyl methacrylate,
phenoxyethyl methacrylate, isobornyl methacrylate, cyclohexyl
methacrylate and 2-hydroxyethyl methacrylate, vinyl esters'
such as vinyl acetate, styrene and vinyl chloride and
monoethylenically unsaturated monomers containing thiol
groups, such as mercaptoethyl (meth)acrylate, vinyl mercaptan
and allyl mercaptan. Preferred monoethylenically unsaturated
monomers include, methyl methacrylate, isobornyl methacrylate,
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-3 0-
phenoxyethyl methacrylate, cyclohexyl methacrylate, vinyl
chloride, mercaptoethyl (meth)acrylate, vinyl mercaptan and
allyl mercaptan and mixtures thereof. If used in the
polymerizable composition, third monomer (c)(i) is typically
present in an amount of not greater than 30 o by weight,
preferably not greater than 20 o by weight, and more
preferably not greater than 10 % by weight, based on the total
weight of the polymerizable composition.
Further optionally included in the compositions of the
present invention is an anhydride monomer having. at least one
polymerizable ethylenically unsaturated group, preferably a
radically polymerizable group, which is described in the
discussion of third monomer (c)(ii) above. Specific examples
of suitable anhydride monomers include, but are not limited
to, methacrylic anhydride, acrylic anhydride, malefic
anhydride, 1-cyclopentene-1,2-dicarboxylic anhydride, itaconic
anhydride and mixtures of such anhydride monomers. If used in
the polymerizable composition, anhydride monomer (c)(ii) is
typically present in an amount of not greater than 40 o by
weight, preferably not greater than 35 °s by weight and more
preferably not greater than 30 °s by weight, based on the total
weight of the polymerizable composition.
The polymerizable composition of the present invention,
may yet further optionally comprise a polythiol monomer (d)
having at least two thiol groups. The polythiol monomer (d)
may be selected from any one or more of those polythiol
monomers as recited and described previously herein with
regards to the preparation the precursor of the first monomer.
Polymerization of the polymerizable organic composition
of the present invention may be accomplished by adding to the
composition an initiating amount of material capable of
generating free radicals, such as organic peroxy compounds or
azobis(organonitrile) compounds, i.e., an initiator. Methods
for polymerizing compositions having therein monomers
containing radically polymerizable groups are well known to
the skilled artisan and any of those well known techniques may
be used to polymerize the aforedescribed polymerizable organic
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-31-
compositions. Such polymerization methods include thermal
polymerization, photopolymerization or a combination thereof.
Examples of suitable organic peroxy compounds, that may
be used as thermal polymerization initiators include:
peroxymonocarbonate esters, such as tertiarybutylperoxy 2-
ethylhexyl carbonate and tertiarybutylperoxy isopropyl
carbonate; peroxyketals, such as l,l-di-(t-butyl peroxy)-
3,3,5-trimethylcyclohexane; peroxydicarbonate esters, such as
di(2-ethylhexyl) peroxydicarbonate, di(secondary butyl)
peroxydicarbonate and diisopropylperoxydicarbonate;
diacyperoxides, such as 2,4-dichlorobenzoyl peroxide,
isobutyryl peroxide, decanoyl peroxide, lauroyl peroxide,
propionyl peroxide, acetyl peroxide, benzoyl peroxide, p-
chlorobenzoyl peroxide; peroxyesters such as t-butylperoxy
pivalate, t-butylperoxy octylate, and t-
butylperoxyisobutyrate; methylethylketone peroxide, and
acetylcyclohexane sulfonyl peroxide. Preferred thermal
initiators are those that do not discolor the resulting
polymerizate. A particularly preferred thermal initiator is
l,l-di-(t-butyl peroxy)-3,3,5-trimethylcyclohexane, which is
commercially available from Elf Atochem under the tradename
LUPERSOL 231.
Examples of suitable azobis(organonitrile) compounds,
that may be used as thermal polymerization initiators include:
azobis(isobutyronitrile) and azobis(2,4-
dimethylvaleronitrile).
The amount of thermal polymerization initiator used to
initiate and polymerize the polymerizable organic compositions
of the present invention may vary and will depend on the
particular initiator used. Only that amount that is required
to initiate and sustain the polymerization reaction is
required, i.e., an initiating amount. With respect to the
preferred peroxy compound, 1,1-di-(t-butyl peroxy)-3,3,5-
trimethylcyclohexane, typically between 0.01 and 3.0 parts of
that initiator per 100 parts of monomers (phm) present in the
polymerizable organic composition may be used. More usually,
between 0.05 and 1.0 phm is used to initiate the
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-32-
polymerization. Typically, the thermal cure cycle involves
heating the polymerizable organic composition in the presence
of the initiator from room temperature to 85°C to 130°C over a
period of from 2 hours to 48 hours.
Photopolymerization of the polymerizable organic
composition according to the present invention may be carried
out in the presence of a photopolymerization initiator using
ultraviolet light, visible light, or a combination thereof.
Examples of suitable photopolymerization initiators include
benzoin, benzoin methyl ether, benzoin isobutyl_ether, _
benzophenone, acetophenone, 4,4'-dichlorobenzophenone,
diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one,
1-hydroxycyclohexyl phenyl ketone, 2-isopropylthixanthone and
2,4,6-trimethylbenzoyldiphenylphosphine oxide. The amount of
photopolymerization initiator used to initiate and polymerize
the polymerizable organic compositions of the present
invention vary and will depend on the particular initiator
used. Only that amount that is required to initiate and
sustain the polymerization reaction is required, i.e., an
initiating amount. A preferred photopolymerization initiator
is 2,4,6-trimethylbenzoyldiphenylphosphine oxide. The
photopolymerization initiator is typically used in an amount
from 0.01 o to 2 % by weight, based on the total weight of
monomer components.
The light source used for the photopolymerization is
preferably selected from those which emit ultraviolet light.
The light source is preferably a mercury lamp, a germicidal
lamp or a xenon lamp. Visible light, e.g., sunlight, may also
be used. The exposure time may differ depending upon, e.g.,
the wavelength and intensity of .the light source and the shape
of the mold, and is typically determined empirically.
The amount of thermal polymerization initiator or
photopolymerization initiator and / or the consequent cure
cycle should be adequate to produce a polymerizate according
to the present invention which has an initial (zero second)
Barcol hardness of at least 1, preferably at least 4, e.g.,
from 4 to 35.
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-33-
It should be understood that the polymerizable organic
composition of the present invention may be polymerized in the
absence of a polymerization initiator. In particular,
photopolymerization of the polymerizable organic composition
of the present invention may be achieved in the absence of any
externally added photopolymerization or thermal initiators.
Various conventional additives may be incorporated with
the polymerizable organic composition of the present
invention. Such additives may include light stabilizers, heat
stabilizers, antioxidants, ultraviolet light absorbers,_mold
release agents, static (non-photochromic) dyes, pigments,
polymerization inhibitors to promote stability during storage,
and flexibilizing additives that are not radically
polymerizable, e.g., alkoxylated phenol benzoates and
poly(alkylene glycol) dibenzoates. Anti-yellowing additives,
e.g., 3-methyl-2-butenol, organo pyrocarbonates and triphenyl
phosphite (CAS registry no. 101-02-0), may also be added to
polymerizable organic compositions of the present invention to
enhance resistance to yellowing. Such additives are typically
present in the compositions of the present invention in
amounts totaling less than 10 % by weight, preferably less
than 5 % by weight, and more preferably less than 3 o by
weight, based on the total weight of the polymerizable
composition.
It is also contemplated that a polymerization moderator,
or mixtures of polymerization moderators, may be added to the
polymerizable organic composition of the present invention to
minimize the formation of distortions, such as striations, in
polymerizates obtained therefrom. Suitable polymerization
moderators include for example, dilauryl thiodipropionate,
terpinolene, 1-isopropyl-4-methyl-1,4-cyclohexadiene, 1-
isopropyl-4-methyl-1,3-cyclohexadiene, alpha-methyl styrene,
2,4-diphenyl-4-methyl-1-pentene, l,l-diphenylethylene, cis-
1,2-diphenylethylene, 2,6-dimethyl-2,4,6-octatriene, 4-tert-
butylpyrocatechol, and mixtures thereof. The polymerization
moderator may be added to the polymerizable organic
composition of the present invention in an amount from 0.01
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-34-
percent to 10 percent by weight, preferably from 0.1 percent
to 8 percent by weight and more preferably from 0.3 percent to
percent by weight, based on the total weight of the
polymerizable organic composition.
5 Polymerizates obtained from polymerization of
polymerizable organic compositions of the present invention
will be solid, and preferably transparent, e.g., suitable for
optical or ophthalmic applications. The polymerizates of the
present invention will also have a refractive index of from
about 1.57 to about 1.80, preferably about 1.60.to about 1.75;
an adequately high Abbe number, such as an Abbe number of at
least about 30, preferably at least about 33; and an initial
(zero second) Barcol hardness of at least 1. More preferably,
the refractive index will be at least 1.6, even more
preferably at least 1.63 and most preferably at least 1.65,
and have a more preferable Abbe number of at least 35. Solid
articles that may be prepared from polymerizable organic
compositions of the present invention include, but are not
limited to, optical lenses, such as plano and ophthalmic
lenses, sun lenses, windows, automotive transparencies, e.g.,
windshields, sidelights and backlights, and aircraft
transparencies, etc.
When used to prepare photochromic articles, e.g., lenses,
the polymerizate should be transparent to that portion of the
electromagnetic spectrum which activates the photochromic
substances) incorporated in the matrix, i.e., that wavelength
of ultraviolet (UV) light that produces the colored or open
form of the photochromic substance and that portion of the
visible spectrum that includes the absorption maximum
wavelength of the photochromic substance in its UV activated
form, i.e., the open form. Photochromic substances that may
be utilized with the polymerizates of the present invention
are organic photochromic compounds or substances containing
same that may be incorporated, e.g., dissolved, dispersed or
diffused into such polymerizates.
A first group of organic photochromic substances
contemplated for use to form the photochromic articles of the
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-35-
present invention are those having an activated absorption
maximum within the visible range of greater than 590
nanometers, e.g., between greater than 590 to 700 nanometers.
These materials typically exhibit a blue, bluish-green, or
bluish-purple color when exposed to ultraviolet light in ari
appropriate solvent or matrix. Examples of classes of such
substances that are useful in the present invention include,
but are not limited to, spiro(indoline)naphthoxazines and
spiro(indoline)benzoxazines. These and other classes of such
photochromic substances are described in the open literature.
See for example, U.S. Patents: 3,562,172; 3,578,602;
4,215,010; 4,342,668; 5,405,958; 4,637,698; 4,931,219;
4,816,584; 4,880,667; 4,818,096. Also see for example:
Japanese Patent Publication 62/195383; and the text,
Techniques in Chemistry, Volume III, "Photochromism," Chapter
3, Glenn H. Brown, Editor, John Wiley and Sons, Inc., New
York, 1971.
A second group of organic photochromic substances
contemplated for use to form the photochromic articles of the
present invention are those having at least one absorption
maximum and preferably two absorption maxima, within the
visible range of between 400 and less than 500 nanometers.
These materials typically exhibit a yellow-orange color when
exposed to ultraviolet light in an appropriate solvent or
matrix. Such compounds include certain chromenes, i.e.,
benzopyrans and naphthopyrans. Many of such chromenes are
described in the open literature, e.g., U.S. Patents
3,567,605; 4,826,977; 5,066,818; 4,826,977; 5,066,818;
5,466,398; 5,384,077; 5,238,931; and 5,274,132.
A third group of organic photochromic substances
contemplated for use to form the photochromic articles of the
present invention are those having an absorption maximum
within the visible range of between 400 to 500 nanometers and
another absorption maximum within the visible range,of between
500 to 700 nanometers. These materials typically exhibit
colors) ranging from yellow/brown to purple/gray when exposed
to ultraviolet light in an appropriate solvent or matrix.
CA 02391854 2005-O1-24
-36-
Examples of these substances include certain benzopyran
compounds, having substituents at the 2-position of the pyran
ring and a substituted or unsubstituted heterocyclic ring,
such as a benzothieno or benzofurano ring fused to the benzene
portion of the benzopyran. Such materials are the subject of
U.S. Patent No. 5,429,774.
Other photochromic substances contemplated are
photochromic organo-metal dithizonates, i.e., (arylazo)-
thioformic arylhydrazidates, e.g., mercury dithizonates, which
are described in, for example, U.S. Patent 3,361.,706.
Fulgides and fulgimides, e.g. the 3-furyl and 3-thienyl
fulgides and fulgimides, are described in U.S. Patent
4,931,220 at column 20, line 5 through column 21, line 38.
The photochromic articles of the present
invention may contain one photochromic substance or a mixture
of photochromic substances, as desired. Mixtures of
photochromic substances may be used to attain certain
activated colors such as a near neutral gray or brown.
Each of the photochromic substances described herein may
be used in amounts and in a ratio (when mixtures are used)
such that a polymerizate to which the mixture of compounds is
applied or in which they are incorporated exhibits a desired
resultant color, e.g., a substantially neutral color such as
shades of gray or brown when activated with unfiltered
sunlight, i.e.,-as near a neutral color as possible given the
colors of the activated photochromic substances. The relative
amounts of the aforesaid photochromic substances used will
vary and depend in part upon the relative intensities of the
color of the activated species of such compounds, and the
ultimate color desired.
The photochromic compounds or substances described herein
may be applied to or incorporated into the poiymerizate by
various methods described in the art. Such methods include
dissolving or dispersing the substance within the
polymerizate, e.g., imbibition of the photochromic substance
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-37-
into the polymerizate by immersion of the polymerizate in a
hot solution of the photochromic substance or by thermal
transfer; providing the photochromic substance as a separate
layer between adjacent layers of the polymerizate, e.g., as a
part of a polymer film or polymer layer; and applying the
photochromic substance as a coating or as part of a coating or
polymer layer placed on the surface of the polymerizate. The
term "imbibition" or "imbibe" is intended to mean and include
permeation of the photochromic substance alone into the
polymerizate, solvent assisted transfer absorption of the
photochromic substance into a porous polymer, vapor phase
transfer, and other such transfer mechanisms. One example of
an imbibing method includes the steps of coating the
photochromic article with the photochromic substance; heating
the surface of the photochromic article; followed by removing
the residual coating from the surface of the photochromic
article.
The amount of photochromic substance or composition
containing same applied to or incorporated into the
polymerizate is not critical provided that a sufficient amount
is used to produce a photochromic effect discernible to the
naked eye upon activation. Generally such amount can be
described as a photochromic amount. The particular amount
used depends often upon the intensity of color desired upon
irradiation thereof and upon the method used to incorporate or
apply the photochromic substances. Typically, the more
photochromic substance applied or incorporated, the greater is
the color intensity. Generally, the amount of total
photochromic substance incorporated into or applied to a
photochromic optical polymerizate may range from 0.15 to
0.35 milligrams per square centimeter of surface to which the
photochromic substances) is incorporated or applied.
It is also contemplated that photochromic substances may
be added to the polymerizable organic compositions of the
present invention prior to curing. However, when this is done
it is preferred that the photochromic substances) be
resistant to potentially adverse interactions with
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-3 8-
initiators) that may be present and / or the polythiol
monomer and the sulfide linkages that form within the
polymerizate. These adverse interactions can result in
deactivation of the photochromic substance(s), e.g., by
trapping them in either an open or closed form. Photochromic
substances can also include photochromic pigments and organic
photochromic substances encapsulated in metal oxides, the
latter of which are described in U.S. Patents 4,166,043 and
4,367,170. Organic photochromic substances sufficiently
encapsulated within a matrix of an organic polymerizate, as
described in U.S. Patent 4,931,220, may also be incorporated
into the polymerizable organic compositions of the present
invention prior to curing.
EXAMPhE 1
Thioglycerol bis(2-mercaptoacetate) is a preferred
polythiol monomer of the present invention, in which R1 and Rz
are each methylene with reference to general formula I.
Thioglycerol bis(2-mercaptoacetate) was prepared from the
following ingredients.
Ingredient Amount (grams)
Charge 1
3-mercapto-1,2-propanediol 1995
2-mercaptoacetic acid 2333
methane sulfonic acid 14.2
Charge 2
aqueous ammonia (a) 4218
(a) An aqueous solution of 5 o by weight ammonia.
The ingredients of Charge 1 were added to a five liter
round bottom flask equipped with a magnetic stirrer, a
thermocouple and heating mantle coupled through a temperature
feed-back control device, and a vacuum distillation column. A
vacuum of from 5 to 10 millimeters (mm) of Hg was drawn and
the reaction mixture was heated to and held at 70°C for a
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-3 9-
period of 4 to 5 hours while water was collected from the
distillation column.
When no more water was observed to be collected from the
distillation column, the reaction mixture was cooled to room
S temperature and transferred to a six liter round bottom flask
equipped with a motor driven stir-blade, a thermocouple and a
water cooled jacket. Charge 2 was added to the mixture, which
was then stirred for 30 to 45 minutes with an accompanying
exotherm of from 10°C to 20°C. Upon cooling to room
temperature, the reaction mixture was left standing to allow
the accumulation of an upper ammonia layer, which was removed
by suctioning with a pipette. The remaining lower layer was
washed three times each with two liters of deionized water.
Vacuum stripping of water from the washed layer yielded 1995
1S grams of thioglycerol bis(2-mercaptoacetate) in the form of a
yellowish oil having a refractive index of 1.5825.
EXAMPLE 2
This example demonstrates the synthesis of an UV-curable
thiourethane monomer of the present invention. In a reaction
vessel equipped with mixing, a thermometer and a water-cooled
reflux condenser, 1 equivalent of tolylene-2,4-diisocyanate
(TDI) was mixed with 3 equivalents of 2,2'-thiodiethanethiol
(DMDS) under ambient conditions for 16 hours to yield a liquid
2S thiourethane prepolymer. 1 equivalent of the prepolymer was
warmed, to which was added 1 equivalent of isocyanatoethyl
methacrylate. The resulting mixture was stirred for 1.5 hours
at 70°C to yield a clear, viscous monomer.
EXAMPLE 3
This example demonstrates the synthesis of a polymerizate
prepared using the UV-cured thiourethane monomer of Example 2.
The casting composition for the polymerizate was as follows:
Component Composition (weight o)
Thiourethane monomer 35
Bisphenol A 2E0 dimethacrylate 30
CA 02391854 2002-05-16
WO 01/36506 PCT/US00/31651
-40-
Styrene 30
2,2'-thiodiethanethiol 5
Darocure 4265 initiator) Q.S.
'a mixture of 2-hydroxy-2-methyl-1-phenyl-1-propanone and
diphenyl-2,4,6-trimethyl benzyl phosphine oxide available from
Ciba Specialty Chemicals, Basel, Switzerland.
The components were charged to a vessel and mixed for several
minutes. The mixture was placed between two flat UV-
transmissive glass molds with a cavity thickness of 3.2 mm.
The mixture in the mold was photopolymerized by-passing-the
mold under an UV light source. The filled mold was passed
under the UV light a first time, exposing a first side of the
mold to the UV light source. The mold was then turned over,
and was passed under the UV light a second time, exposing a
second and opposite side of the mold to the UV light source.
The mold was then held at 120°C for one hour and afterwards
allowed to cool to ambient temperature. A solid polymer sheet
was recovered from the mold, which had a refractive index (D-
line, 20°C) of 1.60, Abbe number of 34 to 35, and an initial
Barcol 934 hardness of 18.
The invention has been described with reference to the
preferred embodiments. Obvious modifications and alterations
will occur to others upon reading and understanding the
detailed description. It is intended that the invention be
construed as including all such modifications and alterations
insofar as they come within the scope of appended claims or
the equivalents thereof.
