Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
I l 69187
INPROVED OXYGEN PERMEABLE HARD AND
SEMI-HARD CONTACT LENS COMPOSITIONS,
METBODS AND ARTICLES OF MANUFACTURE
BACKGROUND OF THE INVENTION
The present invention relates to novel chemical
compounds, polymers made from such compounds and novel
materials and products made from such compounds. In
particular, one important use of the materials made from
the invention is the manufacture of corneal contact lenses.
In recent years, corneal contact lenses have
become more and more popular in the ~nited States and
throughout the world.
The great popularity of contact lenses is easily
understood. One important reason is that such lenses
provide perhaps the best possible manner of achieving
optical correction for the eyes. The lenses fit directly
over the eye, and when properly fitted, are easily retained
in place. Problems common with spectacles, such as inter-
ference with peripheral vision, moving about on the head,
discomfort, and the possibility of improper inter-
pupilary distance, are easily overcome. Contact lenses
provide cosmetic advantages and afford convenience and
increased safety when used in diverse pursuits, particularly
sporting events.
Contact lenses, which were originally made from
glass, were gradually improved as improved materials be-
came available. Now most commonly used contact lenses
~,~
l ~ 69187
are generally subdivided into two types, so-called hard
contact lenses, and soft contact lenses. Each type of lens
has its own advantages, but each also includes certain
disadvantages.
Referring first to the advantages of hard contact
lenses, these lenses provide dimensional stability, so that
the characteristics of an optical prescription will remain
unchanged while the lens is in use in the eye. In some
cases, the eye will actually conform to the contour of the
lens over a period of time so as to improve the vision of
the wearer. Moreover, hard contact lenses are relatively
durable i~ relation to soft lenses.
~ aile hard contact lenses have the above and other
advantages, some patients find such lenses somewhat un-
comfortable in use, and prefer the so-called soft contact
lens. These lenses fall generally into three categories,
namely lenses made from silicone rubber or like materials,
lenses made from "HEMA" (hydroxyethylmethacrylate) or so-
called "hydrogel" lenses, and finally, lenses of the methyl
methacrylate base type, modified by the addition of polymers
such as cellulose acetate butyrate ("CAB"). Soft lenses
readily conform to the eye and are quite comfortable in
short term use. They are extremely thin as well as soft and
pliable. However, they do not provide satisfactory oxygen
transmissibility through the lens.
Referring now to the disadvantage of both soft and
hard contact lenses, neither type of lens is able to be worn
by a user over an extended period of time because both types
of lenses are not enough permeable to the oxygen. As a
result, the cornea is unable to "breathe" properly. Con-
sequently, after a period of time, the cornea be-
comes irritated or perhaps even damaged. More-
over, the lenses sometime tend to adhere to the eye of the
wearer after being in place for an unduly long period of
time, and this can cause discomfort and even damage to the
l l 69187
eye .
In view of the foregoing advantages of contact
lenses, it would ~e even further advantageous if there were
a contact lens that possessed the known advantages of
machinability, dimensional stability, toughness and optical
clarity, and which were also sufficiently oxygen permeable
to be worn by a user for an extended period, such as for
several days, weeks, or even months or more. Users of such
lenses, could wear them for extended periods and still feel
comfortable, could have good vision and not risk injuring
their eyes. Contact lenses which could be worn for an
extended period would eliminate common problems with exist-
ing lenses. These p~-oblems include losing or misplacing the
lenses because of frequent handling, wear and tear occas-
ioned by such handling, and the general inconvenience oflocating and inserting the lenses when they are needed, but
not being worn.
Still further, the anticipated life of an
extended duration contact lens would be lengthened con-
siderably. This is because the requirement for handlingwould be very greatly reduced. At present, the frequent
handling of relatively delicate lenses, and the requirement
that they be c}eaned frequently, is largely responsible for
the premature degeneration of many such lenses. For
example, it is not uncommon for a pair of hydrogel lenses
costing perhaps hundreds of dollars, to last for only about
one year or 50 without cracking or becoming torn as a result
of frequent handling. More sturdy lenses, such as known
types of hard lenses, are not susceptible to tearing or
cracking, but can be scratched by frequent removal and
insertion, and cleaning, particularly if they are dropped
occasionally. Losing the lenses is a realist$c possibility
which could be minimized substantially by having lenses
which are removed weekly, or monthly, or at greater in-
tervals.
Referring now to prior attempts to provide
l l 69187
polymers with increased oxygen permeability, normally, mostor all such known polymers have either been too dimen-
sionally unstable for satisfactory use, or have had other
disadvantages. For example, it is known to add significant
amounts of additives normally intended to increase wett-
ability. While such materials are helpful in proper
amounts, using excess amounts thereof has often tended to
cause proteinaceous matter to deposit on and impair the
transparency of the inner surface of the lens.
While numerous attempts have been made to improve
the oxygen permeability of both hard and soft contact lenses,
the attempts have met with only limited success, parti-
cularly in thicker lenses. Moreover, many soft lens
material provide an environm--nt which is highly suitable
for bacterial growth, and this calls for sterilization
procedures which in turn require the lenses to be handled
frequently.
The present invention, therefore, is intended
from the standpoint of an end use product to provide con-
tact lens materials which are sùfficiently oxygen per-
meable that they may be worn by the user on a greatly
extended basis in relation to prior art lenses, which do
not have the disadvantages associated with known prior
art lenses intended for this purpose.
Referring now to its chemical aspects, the
invention relates to the manufacture of copolymers of an
acrylic or methacrylic material of a known type and novel,
silicone substitute arcylic or methacrylic compounds so as
to produce an oxygen permeable plastic material which is
uniquely suitable for manufacturing novel corneal contactlenses as referred to above. The expression "copolymers"
is sometimes used herein for simplicity in referring to a
polymer which includes two principal comonomers, although
such polymer may incidentally include one or more
additional known monomers in minor amounts for purposes
such as cross-linking, increasing the wettability of the
1169187
final product, or otherwise.
The copolymer compositions and products made
therefrom, are improved over counterpart prior art com-
positions by reason of increased dimensional stability and
improved gas permeability. Such novel compositions also
retain or provide improvements in desirable prior art
characteristics such as optical clarity, the ability to be
cast, molded and machined, and compatability with chemically
bonded, hydrophilic materials adapted to improve the
wettability of the finished product.
Preferably, the compositions comprise high
molecular weight polysiloxanylalkylesters of acrylic
and methacrylic acids and other compositions as monomers,
copolymerized with methacrylates or other esters of
acrylic or methacrylic acids, vinyl carbazole, vinyl
benzenes or vinyl pyrrolidinone.
According to the invention, one comonomer (the
"first" comonomer) is an acrylic or methacrylic ester
silane, substituted with one or more highly substituted
siloxanyl groups. Two such typical comonomers are
nonamethyltetrasiloxanyl- or decamethylpentasiloxanyl-
methacryloxyalkylsilane, which can be copolymerized with
an alkyl acrylate or alkyl methacrylate, (the "second"
comonomer), with this copolymer composition in turn being
cross-linked to a slight degree by cross-lin~ing agents,
and preferably further modified by the addition of
compounds intended to increase the wettability of the
finished copolymer material. This basic polymerization
of the no~el comonomers with known comonomers occurs
through a known double-bond polymerization mechanism.
A certain proportion, such as 10% to 60% of
this compound, is then polymerized with one or more or
other second comonomer compounds having the same or
similar acrylic or methacrylic ester portion, together
with the minor amounts of cross-linking and wetting
agents, referred to above.
1 1 69~87
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One more aspect of the present invention relates
to the method of making the so-called first or novel
comonomers of the invention. According to this method,
chlorosilanes are reacted with hydroxy derivatives of
polysiloxanyl groups, in the presence of pyridine to
bond released hydrochloric acid in the form of pre-
cipitated salt of pyridinium hydrochloride at low
temperatures. The details of this method are brought out
in other portions of the specification. In still another
aspect, the invention relates to alternate methods of
preparing the above or similar products. One alternate
method comprises reacting others, mono-, di- or
methacryloxypropyltrichlorosilanes with an excess of
pyridine and reacting the resulting intermediatc~j with
polysilanols (tetra or penta~ at -509C.
Monomer is removed from these reaction mixtures
by purification following removal of the low molecular
weight materials, with the reaction products being
purified by washing with weak alkalies or like materials.
The novel comonomer compounds of the present
invention can be represented by the following formulas:
1 169187
-- 7 ~
O ~ OSi(CH,),
CH,-C-C-O(CH,).Si(CH~)n - O-Si-CH,
CH, OSi(C~,) 2-0Si (CH,), (3-n)
where n is an integer 0 1 2.
and by:
CH, ~ O-Si(CH,~,
CH,=C-C-O(CH2),Si(CH,)n t ~s -CH,
O
~y,_c -C~,
CH, ~
CH, C-C-O(CH,) Si(CH )n t o~l c;
l O-~i(CH~)~ (3-n)
where n is an integer Df 0, 1 2.
In the alkyl or phenyl ester second principal
comonomer, the alkyl group contains 1 to about 10 carbon
atoms, (typically one to six carbon atoms) and the phenyl
ester contains a single phenyl group, N-vinyl carbazole,
N-vinyl pyrrolidinone, ethyl vinyl benzene and divinyl
benzenes~
One compound which may be used as the first
principal comonomer of the present invention is a
nonamethyltetrasiloxanylmethacryloxypropyldimethylsilane:
l 169187
OSi(CH,),
Il /
CH,-C-C-O(CH,~ ,Si (CH,) ,-O-Sl-CH, (I )
CH, OSi (t H,) ~-OSi (CH,),
another compound is bis(nonamethyltetrasiloxanv1)r,e~hacry`oxy-
propvlmethylsilane:
O OSi(CH,),
CH~=C-C-O(CH2),5i(CH,) O Si CH, (I})
CH, OSi~C~ -OSi (CH,), ~
still another comround is tris(nonamethyltetrasiloxanyl)~eth-
acrvloxyprc,py'silane
O ~ O-Si(C?1.),
Cl`:,~C-C-O(CH~),Si~ Sl-CH, (:11)
CH, O-Sl(CH,~,-O-Si(CH~ .
another suitable compounc' is decamethylren~aslloY.any~-di(~eth-
acryloxypropvldimethylsilane~
CH, O-Si(CH,~,
CH~C-C-OtCH~),Si(CH,)~ - O5i-CH,
O O
CH,-Si-CH, (I~
CH, O
CH,-C-C-O(CH,),Si(CH,), - OSj CH,
O O-Si(CH,),
I 1 69187
One more suitable compound is bis(decamethylpentasilox-
anyl)di-(methacryloxypropylmethylsilane):
C~ O- S i ( CH, ),
CH7~C-g-O(CH7),Si(CH,) ~ OSi-CH,
(H,-Si-CH, (V)
CH, ~ O
CH,-C-C-()(CH7),Si(CH,) ~ OS,-CH,
~ O-'i(~U.), ~
The last suitable compound is tris(decamethylpentasiloxanyl)-
di-(methacryloxypropylsilane):
CH, ¦' ~O-Si~CH,),
CH,~C-~Ct-O(C}¦~),.SiJ 05i-CH,
~Ci-t, - Si - CH, ( \
CH, O
CH,~C-~-0(CH,) ~Si oS t -CU,
O Si (CH,)
l l 69187
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Representative known or second comonomers which
may be employed in the practice of the invention include
the following:
methyl acrylate, methyl methacrylate
ethyl acrylate, ethyl methacrylate
propyl acrylate, propyl methacrylate
isopropyl acrylate, isopropyl methacrylate
2-ethylhexyl acrylate, 2-ethylhexyl methacrylate
cyclohexyl acrylate, cyclohexyl methacrylate
benzyl acrylate, benzyl methacrylate
phenyl acrylate, phenyl methacrylate
N-Yinyl carbazole, N-vinyl pyrrolidinone
3-hydroxy 2-naphtyl methacrylate
ethyl vinyl benzene, divinyl benzenes
dimethyl itaconate, dibutyl itaconate
Such secondary comono~ers are preferably present in an
amount of from about 40% to 90~ of the composition.
Cross-linking monomers include difunctional
compounds such as:
ethyleneglycoldimethacrylate
diethyleneglycoldimethacrylate
triethyleneglycoldimethacrylate
tetraethyleneglycoldimethacrylate
polyethyleneglycoldimethacrylate
divinyl benzene
tetramethyldisiloxane di(methylmethacrylate)
and mixtures thereof. From 0% to about 10% by weight of
such cross-linking monomers may be used.
The wetting agents include, but are not limited
to:
acrylic acid
methacrylic acid
N-vinyl 2-pyrrolidone, and
hydroxyalkyl esters of acrylic and methacrylic
acids,
and mixtures thereof. From 0% to 20% by weight of such
1 1 6~87
11 --
wetting agents may be used in the composition.
In view of the shortcomings of prior art contact lenses and
the compounds and compositions used in making ~hem, in accordance with
one aspect of this invention there is provided an oxygen permeable,
hard or semi-hard, machinable, dimensionally stable, wettable, contact
lens material of high transparency consisting essentially of a polymer
formed by free radical polymerization of
(a) 10% to 60% by weight of at least one silicon-containing
nomer selected from the class consisting of nonamethyltetrasiloxanyl-
methacryloxypropyldimethylsilane having the following formula:
fi /OSi(CH3)3
CH2~c-c-o(cH2)3Si(CH3)2-o-si-cH3
CH3 OSi(CH ) -OSi(CH )
bis(nonamethyltetrasiloxanyl)methacryloxypropylmethylsilane
having the following formula: II
1l OSi(CH3)3
CH2~C-C-O(CH2)3 Si(CH3)- -0 -Si-CH3
CH3 OSf(CH ) -OSi(CH ) 2.
tris(nonamethyltetrasiloxanyl)methacryloxypropylsllane
having the following formula:
. 0-Si(CH3)3 ~ III
CH2~c-c-o(cH2)3si-
CH3 0-Si(CH ) -0-Si(C~l ) 3.
decamethylpentasiloxanyl-di(methacryloxypropyldimethylsilane)
having the following formula:
1 169187
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IV
C~H3 O-Si(CH3)3
2 11 o(CH2)3Si(CH3)2- OSi-CH3
CH3-Si-CH3
CIH3 1
CH2-C-C-O ( CH2~ 3Si ( CH3~ 2-OS~-CH3
O O-Si(CH3)3
bis(decamethylpentasiloxanyl)di(methacryloxypropylmethylsilane)
having the following formula:
CH3 I /O-Sl(CH3)3 j V
CH25C-Icl-O(cH2)3s ~ 3 _ OSi-CH3
CH3-lSi-CH3
cl~3 1 ,
CH2=c-c-o(cH2)3si(cH3)- I \
O L O-Si(CH3)3 2.
tsis(decamethylpentasiloxanyl)di(methacryloxypropylsilane)
having the following formula:
CIH3 /O-Si(CH3)3 VI
~CN ~C-C-O(CH2)3Si- _ OSi-CH3
; CH3-Si-CH3
CIH3 O
CH2~c-c-o(cH2)3si- l ~
O O-Si(CH3)3 3.
and mixtures thereof,
(b) 40% to 90% by weight of at least one secondary comonomer
selected from the group consisting of methyl acrylate, methyl methacrylate,
- 12a - l ~69187
-
ethyl acrylate,ethyl methacrylate, propyl acrylate, propyl methacrylate,
isopropyl acrylate, isopropyl methacrylate, 2-ethylhexyl acrylate,
2-ethylhexyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate,
benzyl acrylate, benzyl methacrylate, phenyl acrylate, phenyl methacrylate,
N-vinyl pryrolidinone, 3-hydroxy 2-naphthyl methacrylate, ethyl vinyl
benzene, divinyl benzene, methyl itaconate, butyl itaconate, dimethyl
itaconate, dibutyl itaconate and mixtures thereof,
(c) 0% to 20% by weight of a monomer adapted to act as a
wetting agent, and
(d) from about 0% to 10% by weight of at least one cross-linking
monomer,
said weight percents of (a), (b), (c) and (d) being based on the total
weight of the entire composition.
In accordance with another aspect of this invention the silicon-
containlng monomer of the oxygen permeable contact lens material is
tris(nonamethyltetrasiloxanyl)methacryloxypropylsllane.
B
1 169187
- 13 -
Chlorine gas is then introduced through the
gas inlet tube. A white precipitate of pyridinium
hydrochloride is formed. The temperature is maintained
in the range of 5-8C, while chlorine is bubbled through
the reaction mixture. Cessation of the exotherm indicates
that the reaction is complete. Pyridinium hydrochloride
is isolated by filtration and then discarded. Then n~
hexane and the excess of pyridine is removed by means
of distillation and the product is analyzed by IR
spectroscopy~ The complete disappearance of Si-H band
at about 2200 cm 1 region concludes that the reaction is
completed.
Example 2
This example illustrates a preparation of a
new and useful monomer, Tris(nonamethyltetrasiloxanyl)-
methacryloxypropylsilane.
Step 1
Nonamethylchlorotetrasiloxane (300 g.) is
dissolved in 1200 ml of diethylether and placed in a 3
liter, 3 necked, round bottom flask equipped with a
mechanical stirrer, a thermometer and additional funnel,
and cooled to 0C in the ice bath. After flushing the
system with nitrogen for 15 minutes, when the temperature
reaches 0C, start titration with saturated aqueous
solution of sodium bicarbonate. The pH of the reaction
mixture is controlled so as to remain neutral. After
all the sodium bicarbonate solution is added, the pH
still remains above 6.9-7.0, the organic layer is
separated and dried over anhydrous magnesium sulfate
for 30 minutes. Magnesium sulfate is filtered by means
of a frit filter type C. Crude nonamethyltetrasiloxanol
i5 holding for Step 2, Example 2.
1 169187
- 14 -
Step 2
Trichloromethacryloxypropylsilane (82 g.) is
dissolved in 700 ml of dry diethylether and placed in a
3 liter, 3 necked, round bottom flask equipped with a
mechanical stirrer, a thermometer and an additional
funnel. The solution is cooled down to -50C ~ith a
dry ice - isopropanol cooling bath. When the temperature
has reached -50C, 85 grams (slight excess) of dry
pyridine is added over a period of about 2 hours, with
the temperature being held at -50C or less during
pyridine addition. At the same temperature, an equimolar
amount of nonamethyltetrasiloxanol, which can be that
prepared as disclosed above, is added in a diethylether
solvent, forming a white precipitate of pyridinium
hydrochloride. When all the nonamethyltetrasiloxanol
has been added, the temperature of the reaction mixture
is increased rapidly to about +30C and stirred for 1/2
hour. The pyridinium hydrochloride is isolated by
filtration and the filter cake is washed with diethylether.
The crude monomer tris~nonamethyltetrasiloxanyl)
methacryloxypropylsilane in diethylether is washed
twice with water (200 ml's each). The upper (organic)
layer is then separated and diethylether is removed by
means of distillation. The crude monomer (III) is
washed with 150 ml of distilled water, and thereafter
twice with a dilute sodium bicarbonate solution, again
with distilled water once, and then dried over anhydrous
magnesium sulfate for 2 hours. The dried monomer is
purified by distilling off all low boiling materials at
85C and 0.1 mm Hg pressure. The purified monomer is
refrigerated until used. Density of the monomer (III)
is 0.98 g/ml at 20C and n2D-1.4185.
Example 3
This example illustrates a preparation of a
new and useful monomer, bis(Decamethylpentasiloxanyl)di-
(methacryloxypropylmethylsilane).
I 1 69~87
- 15 -
Step 1
Decamethyldichloropentasiloxane (375 g.) is
dissolved in 1400 ml of n-hexane and placed in a 3
liter, 3 necked, round bottom flask equipped with a
mechanical stirrer, a thermometer and additional
funnel, and cooled to 0C in the ice bath. After
flushing the system with nitrogen for 15 minutes, when
the temperature reaches 0C, start titration with
saturated aqueous solution of sodium bicarbonate. The
pH of the reaction mixture is controlled so as to
remain neutral. After all the sodium bicarbonate
solution is added, the pH still remains about 6.9-7.0,
the organic layer is separated and dried over anhydrous
magnesium sulfate f~lr 30 minutes. Magnesium sulfate is
filtered by means of a frit filter type C. Crude
decamethyldihydroxypentasiloxane is holding for Step 2,
Example 3.
Dichloromethacryloxypropylmethylsilane (204
g.1 is dissolved in 1000 ml of dry n-hexane and placed
in a 3 liter, 3 necked, round bottom flask equipped
with a mechanical stirrer, a thermometer and an additional
funnel. The solution is cooled down to -50C with a
dry ice - isopropanol cooling bath. When the temperature
has reached -50C, 170 grams (slight excess) of dry
pyridine is added over a period of about 2 hours, with
the temperature being held at -50C or less during
pyridine addition. At the same temperature, 330 grams
of decamethyldihydroxypentasiloxane, which can be that
prepared in Step 1 of Example 3, is added in a n-hexane
solution, forming a white precipitate of pyridinium
hydrochloride. When all the decamethyldihydroxypentasiloxane
has been added, the temperature of the reaction mixture
is increased rapidly to about +30C and stirred for 1/2
hour. ~he pyridinium hydrochloride is isolated by
filtration and the filter cake is washed with n-hexane.
1 1 6gl87
- 16 -
The crude monomer bis(Decamethylpentasiloxanyl~di
~methacryloxypropylmethylsilane~ in n-hexane is washed
twice with water (200 ml's each). ~he upper (organic)
layer is then separated and n-hexane is removed by means
of distillation. The crude monomer (V) is was~ed with
150 ml of distilled water, and thereafter twice with
a dilute sodium bicarbonate solution, again with distilled
water once, and then dried over anhydrous magnesium sulfate
for 2 hours. The dried monomer is purified by distilling
Off all low boiling materials at 85DC and 0.1 mm Hg
pressure. The purified monomer is refrigerated until
used. Density of the monomer (V) is 0.995 g/ml at 20C.
Example 4
This example illustrates the preparation of a
representative oxygen permeable copolymer.
A mixture of 35 parts of the comonomer (III) of
Example 2, 60 parts of methyl methacrylate, 3 parts of
methacrylic acid and 2 parts of diethyleneglycoldimethacry-
late and 0.14% by weight of the entire mixture of tert-
butyl peroxypivalate is placed in a glass dish or tubeand then placed in a vacuum oven which has been purged with
nitrogen. The oven is closed and the temperature is main-
tained at 48C for 24 hours. The monomers react to create
a copolymer plastic which is hard, colorless, transparent,
and rigid. The oxygen permeability should be about
19.6 x lo~ll (cm2/sec)(ml 02/ml x mm Hg) The oxygen
permeability of a disc of polymethylmethacrylate, measured
in the same way is less 0.2 x 10 ll(cm2/sec)(ml 02/ml x mm Hg)
while that of a disc of hydrated polyhydroxyethylmethacryl
ate is 8,x 10 11 (,same units).
Example 5
This example illustrates the preparation of a repre-
sentative oxygen permeable copolymer from another
comonomer (V).
- I 169187
- 17 -
A mixture of 45 parts of novel comonomer (y~
of Example 3, 60 parts of methyl methacrylate, 10 parts
of cyclohexyl methacrylate, 2 parts of N-vinyl pyrrolidone
and 3 parts of triethyleneglycoldimethacrylate and
0.25% by weight of the entire composition of t-butyl
peroxydecanoate is polymerized in a polypropylene dish
or tube at 50C for 24 hours. The resulting copolymer
plastic material is machined, cut, polished, and finished
into a concaYoconVex lens of 0.20 mm thickness. The
lQ oxygen permeability of this lens should ~e about 18.6 x
lQ ll(cm2/sec)(ml 02/ml x mm Hg). (155 mm Hg is
the normal partial pressure of oxygen in a 760 mm Hg
atmosphere.) This particular type of measurement can
be made by a "Schema-Versatae" Model ~0 gas flux meter
which is known and widely used in the contact lens
industry.
The following Examples 6-18 illustrate the
conditions of preparation and properties of copolymers
which contain varying proportions of the novel comonomer
of Example 2 when such comonomers are reacted ~ith one
or more of the following compounds:
methyl methacrylate (MMA)
cyclohexyl methacrylate (CHMA)
methacrylic acid (MAA)
2S N-vinyl pyrrolidone (NVP)
triethyleneglycoldimethacrylate (,Tri-EGDMA)
tetraethyleneglycoldimethacrylate (.TEGDMA)
ethyleneglycoldimethacrylate (,EGDMA)
The siloxane comonomer used in these examples
is that prepared in Example 2, namely, tris(nonamethyl-
tetrasiloxanyl)me~hacryloxypropylsilane (,IIIl, and
which is abbreviated in the table below as C~III),.
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- 18 -
The polymerization is conducted in polypropy-
lene tubes for 24 hours at the temperature shown in the
table~ The table also shows the composition of each
form of polymer, and the temperature at which polymeriza-
tion took place. The properties of the polymer areabbreviated in the right hand corner, with the meanings
of the abbreviations appearing below.
In the examples, the principal polymers are
C(III) and MMA, with the compositions including one or
more other compounds as indicated. MAA provides
wettability, CHMA supplements the MMA to accomplish
better rigidity, and NVP provides increased wettability,
except that, where more than 4 or 5~ NVP is present, a
portion thereof serves as a third monomer. Th TEGDMA,
Tri-EGDMA, EGDMA and DVB (divinylbenzene) are cross-
linking agents.
COMPOSITION, WT., PERCE~T
Tri- TE~
ExamPle C(III) I~MA CH~A ~A NVP EGDM~ TEGD~.~A F,~D~ DVB C PROP.
6 35 57 3 2 3 49 T,H,R
20 7 40 5010 50 T,H,R
8 45 3510 4 2 4 45 T,H,R
9 60 40 45 T,H,R
38 4510 3.5 3 5 47 T,H,R
11 36 2530 4.5 4.5 43 T,H,R
2512 34 4026 4 4 3 46 T,H,R
13 37 2727 5 4 49 T H R
14 25 75 40 T H R
45 T,H R
16 42 2727 2 2 43 T H R
3017 40 4210 4.5 3.5 45 T H,R
18 38 45 8 4.7 3.6 0.7 46 T,H,R
TzTransparent
H=Hard
R=Rigid
Products of the invention herein described as
"hard" have a hardness, measured on the Shore D scale
of about 82-90, (ASTM 2240) while polymethylmethacrylate,
tested the same way, has a hardness of 90-93.
9187
-- 19 --
Example 19
This example illustrates the preparation and
properties of a wettable, oxygen permeable polymer. A
disc is prepared in the manner described in Example 5
from a mixture of 40 parts of the bis(decamethylpenta-
siloxanyl)di(methacryloxypropylmethylsilane) (V) of
Example 3, 40 parts of methyl methacrylate, 5 parts of
N-vinyl pyrrolidone and 15 parts of dimethyl itaconate,
using t-butylperoxypivalate as a catalyst. The polymeriza-
tion is carried out at 48~C for 24 hours. The resultingdisc is colorless, transparent, hard and rigid. The
oxygen permeability of the polymer should be about 23.2
x 10 11 (cm2/sec)(ml 02/ml mm Hg) In this example,
no difunctional cross-linking agent was used.
Example 20
This example illustrates the preparation of a
copolymer of methyl methacrylate and the novel comonomer
~III) referred to in Example 2.
A cylindrical plug of the copolymer is prepared
by polymerizing a mixture of 40 parts of such novel
comonomer (III), 50 parts of methyl methacrylate, S
parts of vinyl carbazole and 5 parts of divinyl benzene,
in the presence of t-butylperoxydecanoate at 45C.
Lenses prepared from the plug are hard, rigid, transparent,
and highly oxygen permeable in relation to prior art
lenses.
Example 21
This example illustrates the preparation of a
copolymer of methyl methacrylate and the novel comonomer
(II), bis(nonamethyltetrasiloxanyl)methacryloxypropyl-
methylsilane. (The novel comonomer (II) is prepared by
the chemistry described in Example 2 or Example 3.)
A mixture of 37 parts of the comonomer (II),
58 parts of methyl methacrylate, 3 parts of methacrylic
I lfi~7
- 20 -
acid and 2 parts of triethyleneglycoldimethacrylate and
0.135% by weight of the entire mixture of t-butyl
peroxypivalate is polymerized in polypropylene tube at
48C for 24 hours; then insert to 108C thermostated
oven for an additional 24 hours to finalize polymerization.
Lenses prepared from this polymer plastic are hard,
rigid, transparent, and highly oxygen permeable.
Example 22
This example illustrates the preparation and
properties of a wettable, oxygen permeable copolymer.
A disc is prepared in the manner described in Example
21 from a mixture of 36 parts of comonomer (IV), deca-
methylpentasiloxanyl-di(methacryloxypropyldimethylsilane).
(The novel comonomer (IV) is prepared by the chemistry
described in Example 2 or Example 3.) 40 parts of
methyl methacrylate, 4 parts of methacrylic acid, 16
parts of dimethyl itaconate and 4 parts of triethylene-
glycoldimethacrylate, using t-butylperoxypivalate as a
catalyst. The polymerization is carried out at 47C
for 24 hours. The resulting disc is colorless, transparent,
hard and rigid.
The previous Examples illustrate the outstanding
properties of the resulting polymers of this invention.
The polymers referred to may be made from the materials
described specifically in detail in the Examples, or
may be made as therein illustrated from the other
monomers described herein. The desirable properties of
the finally produced copolymers result from the use of
one or more of the novel silicone comonomers referred
to herein.
Other additives to the polymers of this
invention, as known in the art, can be made. In all
cases, the polymers are optically clear and transparent
and meet required standards of desirably high oxygen
permeability in semi-rigid and hard contact lenses.
I l 69187
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Even though I have described specific examples
of this invention, there are many variations possible
within the scope of keeping the physical properties as
previously described. Such variations include the use
of mixtures of monomers within the components to comprise
of the required parts of each. For example, two or
more siloxanyl alkyl ester comonomers can be used
instead of a single such comonomer for the component of
the composition. Respectively, two or more cross-
linking agents can be used. Other additives to thecopolymers such as colorants, tints and the like
materials may also be employed within the scope of
normal ranges of this invention.
I CLAIM:
!
