Title of Invention

A METHOD FOR MANUFACTURING AN ARTICLE SUCH AS CONTACT LENS.

Abstract A method for manufacturing an article comprising the steps of: coating a molding surface of a mold or a mold half with a coating effective amount of a high molecular weight coating composition comprising at least one polymer selected from the group consisting of poly(vinyl alcohol), polyethylene oxide, poly(2-hydroxyethyl methacrylate), poly(acrylic acid), poly(methacrylic acid), poly(maleic acid), poly(itaconic acid), poly(acrylamide), poly(dimethylacrylamide), carboxymethylated polymers, polystyrene sulfonic acid, polysulfonate polymers, polysaccharides, glucose amino glycans, block or random copolymers thereof, or mixtures thereof; dispensing a monomer mixture comprising, a silicone-containing hydrogel monomer, into the mold or mold half; and curing the monomer mixture and the coating composition using a dwell time of less than about 5 minutes and under conditions suitable to form an article coated with the coating composition.
Full Text METHOD FOR COATING ARTICLES BY MOLD TRANSFER
Field of the Invention
This invention relates to coated articles including, without limitation,
contact lenses. In particular, the invention relates to coated hydrogel and
silicone-hydrogel articles formed by curing a reaction mixture of article-
forming material in a mold the molding surface of which has a film of the
coating.
Background of the Invention
The use of hydrogels to form articles such as contact lenses is well
known. It is further known to increase the oxygen permeability of hydrogels
by adding silicone-containing monomers to the hydrogel formulations to
produce silicone hydrogels.
Typically, it is desirable to increase the surface wettability of
hydrogel and silicone hydrogel articles by coating the articles with a
hydropbilic coating. Numerous hydrophilic coatings and methods for their
application are known. For example, it is known to apply a coating to a
silicone hydrogel lens using gas plasma. This coating method is
disadvantageous in that it requires dehydration of the lens prior to application
of the plasma treatment, which treatment must be carried out under vacuum
conditions.
Alternatively, it is known to use solution- or solvent-based coatings
to coat lenses. However, these coating methods, as does the plasma
treatment, add steps to the lens manufacturing process and also result in the
production of large quantities of waste. Further, application of a solution-
based coating uniformly over a lens surface requires extremely precise-
process control.
Application of a coating onto a mold into which a lens material is
dispensed also has been disclosed. However, this method has been
successfully demonstrated only with non-silicone hydrogel materials.
Therefore a need exists for a coating method for coating hydrogel and
silicone hydrogel lenses that overcomes one or more of these disadvantages.
Detailed Description of the Invention and Preferred Embodiments
A method for coating hydrogel and silicone hydrogel articles, and
articles made by the method, are provided in which an uncured coating is
first applied to the molding surface of a mold in which an article-forming
material will be cured to form the article. Thus, the article is coated during
the course of curing the material from which it is formed eliminating the
need for additional processing steps after curing is completed. Additionally,
the method permits the thickness and uniformity of the coating to be more
easily controlled than in known coating methods. Finally, because the
method does not rely on specific reaction chemistries for attachment of the
coating to the lens, as do other known coating methods, any of a wide variety
of coatings that cannot be adequately achieved using known coating methods
are made possible.
The invention provides a method for coating articles the method
comprising, consisting essentially of, and consisting of: a.) coating a molding
surface of a mold or a mold half with a coating effective amount of a high
molecular weight coating composition; b.) dispensing a mixture comprising a
hydrogel monomer, a silicone-containing hydrogel monomer, or a
combination thereof into the mold or mold half; and c.) curing under
conditions suitable to form an article coated with the coating composition.
The invention may be used to produce any of a wide variety of coated
articles. Preferably, the invention is used to produce ophthalmic lenses
including, without limitation, contact, intraocular, and onlay lenses. More
preferably, the invention is used to produce contact lenses.
For purposes of the invention, by "melding surface" is meant a
surface used to form a surface of an article. Typically, molded articles are
formed within a mold or between two mold halves. The mold or mold halves
used to form an article have an inner surface, the molding surface, and an
outer non-molding surface. One ordinarily skilled in the art will recognize
that the molding surface will be of the dimensions and surface type requisite
for forming the desired molded article.
By "high molecular weight" is meant an average molecular weight
("Mw") sufficiently high so as to avoid dissolution of the coating into the
monomer mixture used. For purposes of the invention, preferably the
molecular weight is determined using gel permeation chromatography
("GPC") wits a light scattering detector and a high sensitivity refractive
index detector, for example model PL-RI available from Polymer Labs. The
GPC is performed using a phenogel 5 µm linear column equipped with a
guard column of the same components and a solution of 0.5 weight percent
lithium bromide in dimethyl formamide as the eluent. Flow rates are 0.5 mL
per minute with injection volumes from about 10 to about 20 µL. The
precise Mw used will depend upon the coating selected and the monomer
mixture used. In a preferred embodiment, the Mw of the coating is greater
than about 300 kD.
As an alternative, useful coating compositions have a viscosity of a
greater than about 1 cP, preferably at least about 4 cP, at 25 degrees
centigrade. For purposes of the invention, preferably the viscosity is
determined by dissolving the monomer or polymer component in a suitable
solvent and measuring the viscosity at a shear rate of 40/s. Preferably used,
when the article forming material is a silicone hydrogel is 1.00 weight
percent in a 1:1 solvent mixture of ethanol:ethyl lactate or
isopropanol'.isopropyl lactate.
By "hydrogel monomer" is meant is a material that after curing and
hydration is elastomeric and has a water content of about 20 weight percent
or more. By "silicone-containing hydrogel monomer" is meant a hydrogel
monomer that contains one or more silicone groups.
For purposes of the invention, the term "monomer" refers to
compounds having number average molecular weights less than about 700,
that can be polymerized, and to medium to high molecular weight
compounds or polymers, sometimes referred to as macromonomers or
macromers, having number average molecular weights greater than about
700, containing functional groups capable of further polymerization. The
term monomer includes monomers, macromonomers, macromers, and
prepolymers. Prepolymers are partially polymerized monomers or monomers
that are capable of further polymerization.
In preferred embodiment, the invention provides a method for coating
hydrogel and silicone-containing hydrogel articles the method comprising,
consisting essentially of, and consisting of: a.) coating a molding surface of a
mold or a mold half with a coating effective amount of a high molecular
weight hydrophilic coating composition; b.) dispensing a mixture comprising
a hydrogel monomer, a silicone-containing hydrogel monomer, or a
combination thereof into the mold or mold half; and c.) curing under
conditions suitable to form an article coated with the coating composition.
For purposes of the invention, by "hydrophilic" is meant a material that,
when polymerized, exhibits an advancing dynamic contact angle of less than
about 100 degrees in physiological saline.
In a more preferred embodiment, the invention is used to produce
physiologically compatible contact lenses and, thus, provides a method for
coating contact lenses the method comprising, consisting essentially of, and
consisting of: a.) coating a molding surface of a mold or a mold half with a
coating effective amount of a high molecular weight hydrophilic coating
composition; b.) dispensing a mixture comprising a hydrogel monomer, a
silicone-containing hydrogel monomer, or a combination thereof into the
mold or mold half; and c.) curing under conditions suitable to form a contact
lens coated with the coating composition, wherein the lens exhibits
physiological compatibility.
By "physiologically compatibility" or "physiological compatible," is
meant that the lens exhibits clinical performance, in terms of on-eye
wettability and resistance to surface deposits that is equal to or better than
that of an etafilcon A lens. On-eye wettability is determined by measuring
non-invasive, tear break-up time using a tear scope placed between a slit
lamp microscope and a lens wearer's eye. The lens wearer blinks and holds
the eye open while the eye is viewed through the slit lamp, typically at a
magnification of about 16 to 20x. The time between the blink and the first
observed non-wetting of the lens surface is the non-invasive, tear break-up
time. The non-invasive tear break-up time for the lenses of the invention are
equal to or greater than that of an etafilcon A lens or equal to or greater than
about 5 to about 10 sees. Preferably, the lens of the invention exhibit a non-
invasive tear break-up time of about 7 to about 10 sees.
Surface deposition resistance is measured for both the front and back
lens surfaces by scanning the entire lens on eye using a slit lamp with a
magnification of about 16 to about 20x and a beam width and height set at
approximately one-half of the corneal diameter, typically a width of
approximately 2 mm and a beam height of approximately 6 mm. Deposits
may be appear as discrete deposits, such as jelly bumps, or as oily patches or
film and will move with the lens during blink or Josephson Push-Up testing.
No observable deposition is a grade 0; grade 1 is about 1 to about 5 percent
of the lens surface with deposition; grade 2 is about 6 to about 15 percent
with deposition; grade 3 is about 16 to about 25 percent deposition and grade
4 is greater than about 26 percent deposition. The surface deposition for the
lenses of the invention are equal to or greater than that of an etafilcon A lens
meaning that less than about 15 % of a clinical population will have Grade 3
or higher deposition after one week of wear.
Coating compositions useful in the invention may contain any of a
wide variety of monomers and polymers known in the art. Preferred are
polyvinyl alcohol), polyethylene oxide, poly(2-hydroxyethyl methacrylate),
poly(methyl methacrylate), poly(acrylic acid), poly(methacrylic acid),
poly(maleic acid), poly(itaconic acid), poly(acrylamide),
poly(methacrylamide), poly(dimethylacrylamide), poly(glycerol
methacrylate), polystyrene sulfonic acid, polysulfonate polymers, polyvinyl
pyrrolidone), carboxymethylated polymers, such as carboxymethylcellulosc,
polysaccharides, glucose amino glycans, polylactic acid, polyglycolic acid,
block or random copolymers of the aforementioned, and the like, and
mixtures thereof. Preferably, poly(2-hydroxyethyl methacrylate), polyvinyl
pyrrolidone), poly(acrylic acid), poly(methacrylic acid),
poly(meth)acrylamide, or poly(acrylamide) is used. More preferably, poly(2-
hydroxyethyl methacrylate) is used.
The coating composition may, and for spin coating purposes
preferably does, include a low boiling point, or less than about 90°C, solvent
and a high boiling point, or greater than about 100°C, solvent. Suitable low
boiling solvents include, without limitation, n-methyl pyrrolidone, acetone,
chloroform, and alcohols such as methanol, ethanol, isopropanol, tert-
butanol, and the like. Useful high boiling solvents include, without
limitation, methyl-, ethyl-, and isopropyl lactate, ethylene and (poly)ethylene
glycol, propylene glycol, n-methyl pyrrolidone, dimethyl formamide,
tetrahydrogeraniol, 1-butanol, 1-pentanol, 1-hexanol, 1-octanol, 3-methyl-3-
pentanol, dimethyl-3-octanol, 3-methoxy-1-butanol, 1,2 and 1,4-butanediol,
1,3-hexanediol, water, and the like. Typically, the ratio of the low to the high
boiling solvent will be about 1:1 at room temperature.
Additionally, the coating composition may include, and preferably
includes, at least one surfactant. Suitable surfactants include, without
limitation, anionic surfactants, such as carboxylic acid salts, sulfonic acid
salts, sulfuric acid salts, phosphoric and polyphosphoric acid esters, cationic
surfactants, such as long chain amines and their salts, diamines and
polyamines and their salts, quartemary ammonium salts, amine oxides,
nonionic surfactants, such as polyoxyethylenated alkylphenols, alkyl phenol
ethoxylates, polyoxyethylenated straight chain alcohols, polyethoxylated
polyoxypropylene glycols, polyethoxylated polydimethylsiloxane
copolymers, fluorinated alkane ethoxylate copolymers, and long chain
carboxylic acid esters, zwitterionic surfactants, such as pH-sensitive and pH
insensitive surfactants, and the like, and combinations thereof. The specific
type and amount of surfactants used will depend upon the other components
of the coating composition and the molding surface used. Typically, greater
than or equal to about 0.001 weight percent and less than or equal to about 5
weight percent based on the total weight of the coating composition will be
used.
In a first step of the method of the invention, a coating effective
amount of a suitable coating composition is coated onto the molding surface
of a mold or mold half. Preferably, all exterior surfaces of the article are
coated and, thus, preferably the entire or substantially the entire molding
surfaces of both mold halves are coated. One ordinarily skilled in the art will
recognize that one of the mold half's molding surfaces may be coated with a
coating different or the same as that used on the other mold half's molding
surface.
The thickness of the coating composition, when dry, on the molding
surface of the mold must be such that an article with an acceptable surface
roughness results. In embodiments in which the article is a contact lens,
preferably a peak-to-peak surface roughness of the hydrated lens is less than
about 500 nrn is desirable. Thus, by coating effective amount is meant an
amount of the coating composition sufficient to provide a dry film thickness
of the coating composition on the molding surface that will result in a
hydrated article with an acceptable surface roughness and for contact lenses
preferably a hydrated lens peak-to-peak surface roughness of less than about
SOO nm. More preferably, for contact lens embodiments, the amount of
coating composition used is an amount sufficient to produce a dry film
thickness of at least about 5 nm and no more than about 70 nm, preferably at
least about 5 nm and no more than about SO nm, more preferably at least
about 20 nm and no more than about 40 nm.
The coating composition may be applied to the molding surface by
any suitable method including, without limitation, compression, swabbing,
spray coating, ink jet printing, aerosolization, nebulization, dip coating, spin
coating, and the like and combinations thereof. Preferably, spin coating is
used. Also, preferably, the coating is dried, or rendered non-tacky, prior to
introduction of the article forming material into the mold. Drying may be
carried out using any suitable method, but preferably is carried out at
temperatures up to about the glass transition temperature ("Tg") of the mold
material in air or under vacuum followed by equilibration under a blanket of
nitrogen at any temperature up to about the Tg of the mold material. During
the vacuum exposure process, cold traps or other filters preferably are used to
prevent contamination of the mold.
In a spin coating method, the coating composition preferably has a
lower surface tension than that of the molding surface's surface energy.
More preferably, the surface tension of the coating composition is greater
than about 3 dynes/cm below that of the surface energy of the molding
surface to which it is applied when measured at the coating application
temperature. Most preferably, the surface tension of the coating composition
is more than 8 dynes/cm below that of the surface energy of the molding
surface.
In a preferred spin coating method for use in forming contact lenses,
spin coating is used to deposit a coating of a dry thickness of about 5 to about
70 run onto a molding surface of a mold. If the surface tension of the coating
differs from the surface energy of the mold by greater than about 8 dynes/cm
when measured at the coating application temperature, a suitable spin profile
is at least about 6,000 and no more than about 8,000 RPM using at least
about 2 and no more than about 20 µl of coating composition and spinning
for at least about 3 sec. If the surface tension difference is less than about 8
dynes/cm, the mold is spun up to at least about 3,000 and no more than about
5,000 RPM using at least about 2 and no more than about 10µl of coating
composition and then the mold is span up to at least about 7,000 and more
than about 10,000 RPM for at least about 3 seconds prior to stopping.
Any excess coating accumulating at the mold edges must be removed
and removal may be carried out by any convenient method including, without
limitation, swabbing the excess, removing the excess using vacuum, solvent,
washing or pressurized air jet. Preferably, the excess is removed using an air
jet. In using the air-jet, it is critical that spinning is started prior to the jet
being turned on and, preferably, the air jet pressure is equal to or greater than
about 10psi.
In the second step of the method of the invention, an article-forming
material that is a mixture comprising a hydrogel monomer, a silicone-
containing hydrogel monomer, or combinations thereof is dispensed into the
mold or mold half. Useful hydrogel monomers are known and include,
without limitation, hydrophilic monomers, preferably acrylic- or vinyl-
containing. Hydrogel monomers that may be used include, without
limitation, polyoxyethylene polyols having one or more of the terminal
hydroxy groups replaced with a functional group containing a polymerizable
double bond. Suitable monomers include, without limitation, polyethylene
glycol, ethoxylated alkyl glucoside and ethoxylated bisphenol A reacted with
one or more equivalents of an end-capping group such as isocyanatoethyl
methacrylate, methacrylic anhydride, methacryloyl chloride, vinylbenzoyl
chloride, or the like, to produce a polyethylene polyol having one or more
terminal polymerizable olefinic groups bonded to the polyethylene polyol
through linking moieties such as carbamate or ester groups. Additional
examples of hydrogel monomers include, without limitation, hydrophilic
vinyl carbonate or vinyl carbamate monomers as disclosed in U.S. Patent No.
5,070,215 and the hydrophilic oxazolone monomers as disclosed in U.S.
Patent No. 4,910,277, both references incorporated herein in their entireties
by reference.
The term "vinyl-type" or "vinyl-containing" monomers refer to
monomers containing the vinyl grouping (-CH=CH2) and are generally
highly reactive. Such hydrophilic vinyl-containing monomers are known to
polymerize relatively easily. "Acrylic-type" or "acrylic-containing"
monomers are those monomers containing the acrylic group: (CH2=CRCOX)
wherein R is H or CH3, and X is O or N and which are known to polymerize
readily such as, without limitation, N,N-dimethyl acrylamide (DMA), 2-
hydroxyethyl methacrylate (HEMA), glycerol methacrylate, 2-hydroxyethyl
methacrylamide, polyethyleneglycol monomethacrylate, methacrylic acid and
acrylic acid.
The preferred hydrogel monomers used to make the silicone-
containing hydrogel useful in the invention may be either acrylic- or vinylic-
containing and the monomers themselves may be crosslinkers. Useful
vinylic-containing monomers include, without limitation, N-vinyl lactams,
such as N-vinyl pyrrolidone ("NVP"), N-vinyl-N-methyl acetamide, N-vinyl-
N-ethyl acetamide, N-vinyl-N-ethyl formamide, and N-vinyl formamide with
N-vinyl pyrrolidone being preferred.
Particularly useful silicone-containing hydrogel monomers include
those that contains at least two [-Si-O-] repeating units. Preferably, the total
Si and attached O are present in the silicone-containing monomer in an
amount greater than about 20 weight percent, and more preferably greater
than about 30 weight percent of the total molecular weight of the silicone-
containing monomer.
Preferred silicone-containing hydrogel monomers are of the following
of Structure I:
wherein R51 is H or CH3, q is 1,2, or 3 and for each q, R52, R53 and R54 are
independently an alkyl or an aromatic, preferably ethyl, methyl, benzyl,
phenyl, or a siloxane chain comprising from 1 to 100 repeating Si-O units, p
is 1 to 10, r = (3-q), X is O or NR55, where R55 is H or a alkyl group with 1 to
4 carbons, a is 0 or 1, and L is a divalent linking group which preferably
comprises from 2 to 5 carbons, which may also optionally comprise ether or
hydroxyl groups, for example, a polyethylene glycol chain. Examples of
such monomers include, without limitation,
methacryloxypropylbis(trimethylsiloxy)methylsilane,
methacryloxypropyltris(trimethylsiloxy)methylsilane,
methacryloxypropyipentamethyidisiloxane, and (3-methacryloxy-2-
hydroxypropyloxy)propylbis(trimethylsiloxy)methylsilane.
It is more preferred to use linear mono-alkyl terminated
polydimethylsiloxanes ("mPDMS") such as those shown in the following
Structure II:
where b is a distribution having a most frequently occurring b value and that
b value is 0 to 100, preferably 8 to 10; Rsg is a group containing a free radical
polymerizable ethylenically unsaturated moiety, preferably methacrylate,
methacrylamide, styryl, N-vinyl amide, N-vinyl lactams, vinyl carbonates,
vinyl carbamates, maleate, or fumarate; each R59 is independently an alkyl, or
aryl group, which may be further substituted with alcohol, amine, ketone,
carboxylic acid or ether groups, preferably unsubstituted alkyl or aryl groups,
more preferably methyl; and R60 is an alkyl, or aryl group, which may be
further substituted with alcohol, amine, ketone, carboxylic acid or ether
groups, preferably unsubstituted alkyl or aryl groups, preferably a C1-10
aliphatic or aromatic group which may include hetero atoms, more preferably
C3-8 alkyl groups, most preferably butyl.
Additional silicone-containing hydrogel monomers may be combined
with the silicone-containing hydrogel monomers of Stuctures I and II to form
the articles produced by the method of the invention. Any known silicone-
containing hydrogel monomer useful for making silicone-containing
hydrogels can be used in combination with the silicone-containing hydrogel
monomer of Structure I and II to form the articles of this invention. Many
silicone-containing hydrogel monomers useful for this purpose are disclosed
in U.S. Patent No. 6,020,445 incorporated herein in its entirety by reference.
Useful additional silicone-containing hydrogel monomers combined with the
silicone-containing monomers of Structure I to form the silicone hydrogels of
this invention are the hydroxyalkylamine-functional silicone-containing
monomers disclosed in U.S. Patent No. 5,962,548 incorporated herein in its
entirety by reference. The preferred silicone-containing linear or branched
hydroxyalkylamine-functional monomers comprising a block or random
monomer of the following structure:
Structure III
wherein:
where n and m each is a distribution having a most frequently occurring n
and m value, respectively and that n value is 0 to 500 and that m value is 0 to
500 and (n + m) = 10 to 500 and more preferably 20 to 250; R2, R4, R5, R6
and R7 are independently a alkyl, or aryl group, which may be further
substituted with alcohol, ester, amine, ketone, carboxylic acid or ether
groups, preferably unsubstituted alkyl or aryl groups; and R1, R3 and R8 are
independently an alkyl, or aryl group, which may be further substituted with
an alcohol, ester, amine, ketone, carboxylic acid or ether group, preferably
unsubstituted alkyl or aryl groups, or are the following nitrogen-containing
structure:
Structure IV
with the proviso that at least one of R1, R3, and R8 are according to Structure
IV, wherein R9 is a divalent alkyl group such as -(CH2)s- where s is from 1.
to 10, preferably 3 to 6 and most preferably 3;
R10 and R11 are independently H, a alkyl or aryl group which may be further
substituted with an alcohol, ester, amine, ketone, carboxylic acid or ether
group, or has the following structure:
Structure V
where R14, is H, or a polymerizable group comprising acryloyl,
methacryloyl, styryl, vinyl, allyl or N-vinyl lactam, preferably H or
methacryloyl; R16 is either H, a alkyl or aryl group which can be further
substituted with alcohol, ester, amine, ketone, carboxylic acid or ether
groups, or a polymerizable group comprising acrylate, methacrylate, styryl,
vinyl, allyl or N-vinyl lactam, preferably alkyl substituted with an alcohol or
methacrylate; R12, R13 and R15 are independently H, an alkyl or aryl, which
can be further substituted with alcohol, ester, amine, ketone, carboxylic acid
or ether groups, or R12 and R15, or R15 and R13 can be bonded together to
form a ring structure, with the proviso that at least some of the Structure IV
groups on the monomer comprises polymerizable groups. R12, R13 and R15
are preferably H.
In alternative embodiments, the silicone-containing hydrogel
mixtures useful in this invention, composed of the silicone-containing
hydrogel monomers of either or both Structure I and Structure II also may
contain hydrophilic monomers. The hydrophilic monomers optionally used
can be any of the known hydrophilic monomers useful in making hydrogels.
The preferred hydrophilic monomers used to make the silicone-
containing hydrogel monomers of this invention may be either acrylic- or
vinyl-containing. Such monomers may themselves be used as crosslinking
agents. Hydrophilic vinyl-containing monomers that may be incorporated
into the silicone-containing hydrogels of the present invention include
monomers such as N-vinyl lactams (e.g. NVP), N-vinyl-N-methyl acetamide,
N-vinyl-N-ethyl acetamide, N-vinyl-N-ethyl fonnamide, N-vinyl formamide,
with NVP being preferred.
Other hydrophilic monomers that can be employed in the invention
include polyoxyethylene polyols having one or more of the terminal hydroxyl
groups replaced with a functional group containing a polymerizable double
bond. Examples include polyethylene glycol, ethoxylated alkyl glucoside,
and ethoxylated bisphenol A reacted with one or more molar equivalents of
an end-capping group such as isocyanatoethyl methacrylate ("EM"),
methacrylic anhydride, methacryloyl chloride, vinylbenzoyl chloride, or the
like, to produce a polyethylene polyol having one or more terminal
polymerizable olefinic groups bonded to the polyethylene polyol through
linking moieties such as carbamate or ester groups.
Still further examples are the hydrophilic vinyl carbonate or vinyl
carbamate monomers disclosed in U.S. Patents No. 5,070,215, and the
hydrophilic oxazolone monomers disclosed in U.S. Patents No. 4,910,277,
both references incorporated herein in their entireties by reference. Other
suitable hydrophilic monomers will be apparent to one skilled in the art.
More preferred hydrophilic monomers which may be incorporated
into the polymer of the present invention include hydrophilic monomers such
as N,N-dimethylacrylamide ("DMA"), 2-hydroxyethyl methacrylate
("HEMA"), glycerol methacrylate, 2-hydroxyethyl methacrylamide, NVP,
polyethyleneglycol monomethacrylate, methacrylic acid and acrylic acid with
DMA being the most preferred.
Other monomers that can be present in the reaction mixture used to
form the hydrogel or silicone-containing hydrogel monomer mixtures useful
in this invention include ultra-violet absorbing monomers, reactive tints,
pigments, and the like. Additional processing aids such as release agents or
wetting agents can also be added to the reaction mixture.
A polymerization initiator preferably is included with the hydrogel or
silicone-containing hydrogel monomer mixture. An initiator also may be
used in the coating composition, but is not preferred. The coating
composition and monomer mixture initiators may be the same or different.
The polymerization initiators used may be visible light, thermal, an
ultraviolet initiators, or the like, or a combination thereof. These initiators
are well known in the art and commercially available. The initiator may be
used in catalytically effective amounts which is an amount sufficient to
initiate the polymerization reaction desired Generally, about 0.1 to about 2
parts by weight per 100 parts of the hydrogel or silicone hydrogel will be
used.
The monomer mixture is dispensed into the coated mold. The
hydrogel or silicone-containing hydrogel monomer mixture may be dispensed
into the mold or mold half by any convenient means including, without
limitation, pipetting, dispensing via syringe, pumping via automated or
manual pump, and the like and combinations thereof. In the next step of the
invention, the hydrogel or silicone-containing hydrogel monomer mixture is
cured, or polymerized to form a coated article. Dwell time, or the elapsed
time from which the monomer mixture is dispensed into the mold until
curing commences is critical because the coating composition is soluble in
the hydrogel and silicone-containing hydrogel monomer mixtures. Dwell
time must be less than about S minutes and preferably is less than about 45
sees.
The curing additionally is carried out under conditions suitable for
curing the coated article to be formed. Suitable conditions will depend on a
number of factors including, without limitation, the amount and type of the
coating composition and monomer mixture used, the article to be formed,
and the nature, i.e., visible light or heat, of the cure used. The determination
of the precise conditions required are within the ability of one ordinarily
skilled in the art.
Curing of the monomer mixture may be initiated using the
appropriate choice of heat, visible or ultraviolet light, or other means and
preferably is carried out in the presence of a polymerization initiator. For
contact lens production, the preferred initiator is a 1:1 blend of 1-
hydroxycyelohexyl phenyl ketone and bis(2,6-dimethoxybenzoyl)-2, 4,4-
trimethylpentyl phosphine oxide and the preferred method of polymerization
initiation is visible light For some monomer reaction mixtures it is preferred
to cure the reaction mixtures at temperatures slightly above room
temperature, such as 25-90°C, so as to prevent phase separation of the
components. In a particularly preferred embodiment for contact lens
production, the reaction mixture is precured at about 45 °C followed by
through-curing at about 70°C.
The resulting article will be coated with the coating composition
coated onto the molding surface of the mold. After curing of the monomer
mixture and coating composition, the resulting article may be treated with a
solvent to remove any diluent used or any traces of unreacted components,
and hydrate the polymer to form the hydrogel. For contact lenses, the solvent
used may be water or an aqueous solution such as physiological saline.
Alternatively, and depending on the solubility characteristics of the
diluent used to make the lens and the solubility characteristics of any residual
unpolymerized monomers, the solvent initially used may be an organic liquid
such as ethanol, methanol, isopropanol, mixtures thereof, or the like, or a
mixture of one or more such organic liquids with water, followed by
extraction with pure water (or physiological saline) to produce a hydrogel or
silicone hydrogel lens swollen with water.
In a preferred embodiment, a silicone-containing hydrogel lens is
made by dispensing into the mold or mold half, and subsequently curing, a
macromer with a reaction mixture that include silicone-containing monomers
and hydrophilic monomers. This technique affords a high level of control of
the structure of the ultimate product.
The macromers may be, and preferably are, made by combining a/an
(meth)acrylate and a silicone in the presence of a Group Transfer
Polymerization ("GTP") catalyst. These macromers typically comprise
copolymers of various monomers. They may be formed in such a way that
the monomers come together in distinct blocks, or in a generally random
distribution. These macromers may furthermore be linear, branched, or star
shaped. Branched structures are formed for instance if polymethacrylates, or
crosslinkable monomers such as 3-(trimethylsiloxy)propyl methacrylate are
included in the macromer. Initiators, reaction conditions, monomers, and
catalysts that can be used to make GTP polymers are known, as for example
described in "Group-Transfer Polymerization" by O.W. Webster, in
Encyclopedia of Polymer Science and Engineering Ed. (John Wiley & Sons)
p. S80, 1987. These polymerizations are conducted under anhydrous
conditions. Hydroxyl-functional monomers, like HEMA, can be
incorporated as their trimethylsiloxy esters, with hydrolysis to form free
hydroxyl group after polymerization. GTP offers the ability to assemble
macromers with control over molecular weight distribution and monomer
distribution on the chains. This macromer is then reacted with a reaction
mixture comprising predominantly polydimethylsiloxane (preferably,
rnPDMS), and hydrophilic monomers.
Preferred macromer components include mPDMS, 3-
methacryloxypropyltris(trimethylsiloxy)silane ('TRIS"), methyl
methacrylate, HEMA, DMA, methacrylonitrile, ethyl methacrylate, butyl
methacrylate, 2-hydroxypropyl-1-methacrylate, 2-hydroxyethyl
methacrylamide and methacrylic acid. It is even more preferred that the
macromer is made from a reaction mixture comprising HEMA, methyl
methacrylate, TRIS, and mPDMS. It is most preferred that macromer is
made from a reaction mixture comprising, consisting essentially of, or
consisting of about 19.1 moles of the trimethylsilyl ether of HEMA, about
2.8 moles of methyl methacrylate, about 7.9 moles of TRIS, and about 3.3
moles of mono-methacryloxypropyl terminated mono-butyl terminated
polydimethylsiloxane, and is completed by reacting the aforementioned
material with about 2.0 moles per mole of 3-isopropenyl-?,?-dimethylbenzyl
isocyanate using dibutyltin dilaurate as a catalyst.
Silicone-containing hydrogels can be made by reacting blends of
macromers, monomers, and other additives such as UV blockers, tints,
internal wetting agents, and polymerization initiators. The reactive
components of these blends typically comprise a combination of hydrophobic
silicone with hydrophilic components. Because these components are often
immiscible because of their differences in polarity, it is particularly
advantageous to incorporate a combination of hydrophobic silicone
monomers with hydrophilic monomers, especially those with hydroxyl
groups, into the macromer. The macromer can then serve to compatibilize
the additional silicone and hydrophilic monomers that are incorporated in the
final reaction mixture. These blends typically also contain diluents to further
compatibilize and solubilize all components. Preferably, the silicone based
hydrogels are made by reacting the following monomer mix: macromer; an
Si8-10 monomethacryloxy terminated polydimethyl siloxane; and hydrophilic
monomers together with minor amounts of additives and photoinitiators. It is
more preferred that the hydrogels are made by reacting macromer; an Si8-10
monomethacryloxy terminated polydimethyl siloxane; TRIS; DMA; HEMA;
and tetraethyleneglycol dimethacrylate ("TEGDMA"). It is most preferred
that the hydrogels are made from the reaction of (all amounts are calculated
as weight percent of the total weight of the combination) macromer (about
18%); an Si8-10 monomethacryloxy terminated polydimethyl siloxane (about
28%); TRIS (about 14%); DMA (about 26%); HEMA (about 5%);
TEGDMA (about 1%), polyvinylpyrrolidone ("PVP") (about 5%); with the
balance comprising minor amounts of additives and photoinitiators, and that
the reaction is conducted in the presence of 20%wt dimethyl-3-octanol
diluent.
The preferred range of the combined silicone-containing monomer of
Structure I and additional silicone-containing monomers, if present in the
reaction mixture, is at least about 5 to about 100 weight percent, more
preferably at least about 10 and no more than about 90 weight percent, and
most preferably at least about 15 and no more than about 80 weight percent
of the reactive components in the reaction mixture. The preferred range of
optional hydrophilic monomer if present in the above invention is at least
about S and no more than about 80 weight percent, more preferably at least
about 10 and no more than about 60 weight percent, and most preferably at
least about 20 and no more than about 50 weight percent of the reactive
components in the reaction mixture. The preferred range of diluent is from
about 0 to no more than about 70 weight percent, more preferably about 0 to
no more than about 50 weight percent, and most preferably about 0 to no
more than about 20 weight percent of the total reaction mixture. The amount
of diluent required varies depending on the nature and relative amounts of
the reactive components.
In a preferred combination of reactive components at least about 10
and no more than about 60, more preferably at least about 15 and no more
than about 50 weight percent of the reactive components is silicone-
containing monomer, at least about 20 and no more than about 50 weight
percent of the reactive components is silicone-containing monomer of
Structure I, at least about 10 and no more than 50 percent of the reactive
components is a hydrophilic monomer, more preferably DMA, at least about
about 0.1 and no more than about 1.0 percent of the reactive components is a
UV or preferably a visible light-active photoinitiator and about 0 to no more
than about 20 weight percent of the total reaction mixture is a secondary or
tertiary alcohol diluent, more preferably a tertiary alcohol.
Mold materials useful in the invention are those that are unreactive to
the coating composition and monomer mixture used. Preferably mold
materials are polyolefins, such as polypropylene, and cyclic polyoelfins, such
as those available under the tradename TOPAS®.
The invention may be further clarified by a consideration of the
following, non-limiting examples.
Examples
In the examples, the following abbreviations are used:
Blue-HEMA product of the base-promoted displacement of one chloride of
Reactive Blue # 4 dye by hydroxyethyl methacrylate.
CGI 1850 1:1 (wt) blend of 1-hydroxycyclohexyl phenyl ketone and
bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentyl phosphine
oxide
DMA N,N-dimethylacrylamide
DOE-120 polyethylene glycol 120 methyl glucose dioleate
EtOH ethanol
HEMA 2-hydroxyethyl methacrylate
IPA isopropanol
mPDMS monomethacryioxypropyl terminated polydimethylsiloxane
Norbloc 2-(2"-hydroxy-5-methacrylyloxyethylphenyl)-2H-
benzotriazole
PVP poly(N-vinyl pynolidone)
TEGDMA tetraethyleneglycol dimethacrylate
TBACB tetrabutyl ammonium-m-chlorobenzoate
THF tetrahydrofuran
TMI 3-isopropenyl-a,a-dimethylbenzyl isocyanate
TRIS 3-methacryloxypropyltris (trimethylsiloxy) silane
Example 1
A predominantly poly-DMA ("pDMA") pre-polymer of
DMArHEMA of n = 70 : n = 4 was made using Group Transfer
Polymerization and functionalized with n = 3 mole equivalents of TMI as
follows. 40 g THF, tetrabutylammonium 3-chlorobenzoate (TBACB, lM
solution n THF, 0.31 mL, 0.00031 moles), 0.09 g bis(dimethylamino)-
methylsilane, 0.7 g p-xylene and 20.23 g (0.1 moles) 2-trimethylsiloxyethyl
methacrylate were charged to a dry, three-necked flask under nitrogen. 4.36
g (0.025 moles) Memyhnmethylsilyl dimethylketene acetal were added to the
mixture while stirring. The reaction was allowed to reach an exothermal
peak and then to cool to 24°C. The solution was diluted with 82g THF and
173.5 g (1.75 moles) DMA was fed through a 100 mL syringe over a two
hour period. The exothermal increase was controlled to below 55 °C by
reducing the feed rate of DMA and cooling the flask with ice. Additional
TBACB (lM solution in THF, 0.94 mL, 0.00094 moles) diluted with 9 mL
of THF was fed slowly during the reaction. 160 g dry THF were added to the
solution after the temperature was dropped back to 36 °C. The reaction was
quenched with a mixture of 3.6 g deionized water, 6.40 g methanol, and 0.06
g dichloroacetic acid at 24 °C after 4 ½ hours of total reaction time. The
quenched solution was allowed to reflux at 65 °C for 5 hours and then
solvents were distilled off while toluene was added until the vapor
temperature reached 110.3 °C. To the toluene solution was added a mixture
of 15.1 g (0.08 moles) TMI and 0.98 g dibutyl tin dilauratc and the mixture
refluxed at 115 °C for 3 hours. The resulting solution was allowed to cool
and was then filtered through a membrane and the solvent evaporated off
under vacuum at 30-45°C.
Two coating formulations were made by dissolving the pre-polymer
into IPA at 25 weight percent based on the total weight of the solution, along
with 0.1 weight percent of DOE-120 surfactant. The coatings each were
applied to the molding surfaces of complementary mold halves of lens molds
made of TOP AS® 5013. Application of the coating was by compression
molding of approximately 3 µl of coating solution onto the molding surface
with a silicone pad. For the front curve molding surface, the pad was
brought into contact with the coating, dropped onto the molding surface,
compressed for approximately 0.5 sec., held for 1 sec., and released over a
period of approximately 2 sec. For the back curve molding surface, the pad
was dropped onto the molding surface, compressed and released over a
period of approximately 0.5 sec. The coating was dried at room temperature
for 30 min. Mean dry coating thicknesses were estimated to vary between 1
and 2 µm based on thickness measurements on flat TOPAS surfaces using
Atomic Force Microscopy ("AFM").
Lenses were cast using the molds by dispensing into the molds a
silicone hydrogel lens material of the following formulation:
100 parts of the above listed formulation were mixed with 20 parts of 3,7-
dimethyl-3-octanol diluent.
Macromer Preparation
To a dry container housed in a dry box under nitrogen at ambient
temperature was added 30.0 g (0.277 mol) of
bis(dimethylamino)methylsilane, a solution of 13.75 ml of a 1M solution of
TBACB (386.0 g TBACB in 1000 ml dry THF), 61.39 g (0.578 mol) of p-
xylene, 154.28 g (1.541 mol) methyl methacrylate (1.4 equivalents relative to
initiator), 1892.13 (9.352 mol) 2-(trimethylsiloxy)ethyl methacrylate (8.5
equivalents relative to initiator) and 4399.78 g (61.01 mol) of THF. To a
dry, three-necked, round-bottomed flask equipped with a thermocouple and
condenser, all connected to a nitrogen source, was charged the above mixture
prepared in the dry box.
The reaction mixture was cooled to 15 °C while stirring and purging
with nitrogen. After the solution reaches 15°C, 191.75 g (1.100 mol) of 1-
trimethylsiloxy-1-methoxy-2-methylpropcnc (1 equivalent) was injected into
the reaction vessel. The reaction was allowed to exotherm to approximately
62 °C and then 30 ml of a 0.40 M solution of 154.4 g TBACB in 11 ml of dry
THF was metered in throughout the remainder of the reaction. After the
temperature of reaction reached 30 °C and the metering began, a solution of
467.56 g (2.311 mol) 2-(trimcthylsiloxy)ethyl methacrylate (2.1 equivalents
relative to the initiator), 3636.6. g (3.463 mol) n-butyl
monomethacryloxypropyl-polydimethylsiloxane (3.2 equivalents relative to
the initiator), 3673.84 g (8.689 mol) TRIS (7.9 equivalents relative to the
initiator) and 20.0 g bis(dimethylamino)methylsilane was added.
The mixture was allowed to exotherm to approximately 38-42 °C and
then allowed to cool to 30 °C. At that time, a solution of 10.0 g (0.076 mol)
bis(dimethylamino)methylsilane, 154.26 g (1.541 mol) methyl methacrylate
(1.4 equivalents relative to the initiator) and 1892.13 g (9.352 mol) 2-
trimethylsiloxy)ethyl methacrylate (8.5 equivalents relative to the initiator)
was added and the mixture again allowed to exotherm to approximately 40
°C. The reaction temperature dropped to approximately 30 °C and 2 gallons
of THF were added to decrease the viscosity. A solution of 439.69 g water,
740.6 g methanol and 8.8 g (0.068 mol) dichloroacetic acid was added and
the mixture refluxed for 4.5 hours to de-block the protecting groups on the
HEMA. Volatiles were then removed and toluene added to aid in removal of
the water until a vapor temperature of 110 °C was reached.
The reaction flask was maintained at approximately 110 °C and a
solution of 443 g (2.201 mol) TMI and 5.7 g (0.010 mol) dibutyltin dilaurate
were added. The mixture was reacted until the isocyanate peak was gone by
IR. The toluene was evaporated under reduced pressure to yield an off-
white, anhydrous, waxy reactive monomer. The macromer was placed into
acetone at a weight basis of approximately 2:1 acetone to macromer. After
24 hrs, water was added to precipitate out the macromer and the macromer
was filtered and dried using a vacuum oven between 45 and 60 °C for 20-30
hrs.
The lens material was cured in the molds using visible light for
approximately 30 min. at 45 °C after which the lenses were demolded,
leached using 100 % IPA, and exchanged into fresh borate-buffered saline
solution. The time between dispensing the lens material into the molds and
the initiation of the cure, or the dwell time, was less than 5 minutes in all
cases.
Lens wettability was measured using dynamic contact angle as
follows. Five samples of each lens type were prepared by cutting out a center
strip approximately 5 mm in width and equilibrating the strip in borate-
buffered saline solution for more than 30 min. Contact angles of the strips
were determined using a Cahn DCA-315 micro-balance. Each sample was
cycled x 4 in borate-buffered saline and the cycles were averaged to obtain
the advancing and receding contact angles for each lens. The contact angles
of the 5 lenses were then averaged to obtain the mean contact angle for the
set.
The advancing contact angles for the lenses from the coated molds
were 65 ± 4°. The advancing contact angle for the uncoated control was 99 ±
8°. This demonstrates that the mold transfer coating dramatically improved
the wettability of the silicone hydrogel lenses.
Examples 2-5
Random copolymers of DMA and HEMA (n = 272 for DMA and n =
23 for HEMA) were prepared using free-radical polymerization as follows.
HEMA (300 mg, 2.31 mmole), DMA (29.7 g, 300 mmole), and 100 mg CGI
1850 were dissolved in 120 mL of 3-methyl-3-pentanol. The mixture was
degassed thoroughly by evacuating for 10 to 15 min., followed by purging
with nitrogen. The evacuating/purging was repeated 3 to 4 times and then
the mixture was placed under a nitrogen environment and transferred to a
crystallizing dish and covered with a watch glass. The mixture was exposed
to visible light, Phillips TL20 W/03T bulbs, for a period of approximately 1
hr and then the polymerization was terminated by exposing the system to
oxygen.
The resulting polymer was precipitated by diluting the mixture with
hexanes. Further purification was carried out by dissolving the polymer in
acetone and re-precipitating with hexanes. The acetone/hexanes sequence
was repeated and the white polymer was washed thoroughly with hexanes
and dried on a rotary evaporator with the product being cut into several small
pieces prior to completion of drying. The yield was 27.0 g (90 %) of a white,
foam-like product.
A portion of the above product was derivatized as its methacrylate
using the following procedure. A three-necked, SO mL, round bottomed flask
was heat dried under vacuum, placed under nitrogen and charged with 10 mL
THF. Pyridine, 5 mL, was added to the flask, followed by 64S mg (7.5
mmole) methacrylic acid. The system was cooled to below S °C and 1.026 g
(9 mmole) methanesulfonyl chloride was added to the solution in a drop-wise
fashion over a period of 5 to 10 min. The mixture was stirred for an
additional 10 min while allowing it to warm to room temperature.
A 250 mL, three-necked flask was charged with 9 g HEMA/DMA
copolymer and 9 mg phenotbiazine. The system was purged with nitrogen
and 50 mL of THF was added to dissolve the compounds. The mixed
anhydride solution was added to the flask via a syringe and the reaction
mixture was stirred overnight at ambient temperature.
The solution was filtered through a sintered glass funnel into 200 mL
of stirred hexanes. The solvents were decanted and the product was purified
by dissolving it in isopropyl acetate, followed by the addition of hexanes.
The polymer was washed with 2 x 50 mL of hexanes and dried in a rotary
evaporator. Further purification was required due to the high methacrylic
acid content The product was dissolved in acetone, followed by
precipitation using hexanes.
A coating formulation of 20 wt percent pDMA/HEMA and 0.1 wt
percent DOE-120 in IPA was applied to TOPAS 5013 molds as in Example
1. Dry coating thickness was greater than 1 mn as measured by AFM. Both
the native polymer and functionalized (with methacrylate) were examined as
coatings. Lenses were made using the silicone hydrogel lens material of
Example 1, except that the dwell time was as set forth on Table 2 below.
Additionally on Table 2 is shown the wettability for the coatings.
The results demonstrate that acceptable wettability, or an advancing contact
angle less than 90°, can be obtained with or without the methacrylate group.
Further, the results show that contact angle is dependent on dwell time, times
of less than 2.5 min. producing the most wettable lens.
Examples 6-9
Poly-HEMA coatings were evaluated for efficacy and wettability.
The coatings were prepared by exposing a solution of HEMA, Blue HEM A,
and IRGACURE 1850 in ethylene glycol to low intensity visible light,
Phillips TL20 W/03T bulbs, using curing times ranging from 1 to 2 hours.
The polymers were isolated after aqueous work-ups followed by several
aqueous washes to remove unreacted components. Polymer molecular
weights of less than about 300 kD were found to be inadequate for use as a
coating polymer with the lens material of Example 1. A poly-HEMA of 360
kD MW, available from Aldrich Chemical Company, was successfully used
as a coating. Coating formulations with differing concentrations of poly-
HEMA were prepared as follows:
Poly-HEMA:water:ethanol:DOE-120= 10:20:70:0.1 wAv
Poly-HEMA:water:ethanol:DOE-120= 15:20:65:0.1 w/w
Poly-HEMA:water:ethanol:DOE-l20 = 20:20:60:0.1 w/w
The coatings were applied to the molding surfaces of TOPAS 5013
molds according to the procedure of Example 1, except that prior to coating,
the molds were treated for of the coating solution onto the mold. Lenses were made using procedures
and the silicone hydrogel lens material of Example 1, except that dwell time
was 45 sec.
The resulting coated lenses were tested for wettability using dynamic
contact angle and for surface roughness using AFM. AFM images were
acquired with contact mode AFM using a 0.06 N/m SiN4 cantilever imaging
in borate-buffered saline solution. Imaging was minimized before data was
acquired and typically was optical zone and on the anterior surface of each lens. Two lenses were
evaluated for a total of 6 images. Mean peak-to-peak roughness values were
calculated using 24 10 x 10 µm areas from these images. Peak-to-peak
roughness was defined as the difference in height between the lowest and the
highest point in the area tested. On Table 3 is shown the results.
The results demonstrate that wettability improved with increasing levels of
poly-HEMA m the coating solution. Additionally, surface roughness
increased with increasing poly-HEMA content with the 20 wt percent poly-
HEMA lens being too rough and misshapen to analyze. The 10 wt percent
poly-HEMA coating produced a dry coating thickness on the mold of
approximately 200 nm. Target peak-to-peak roughness for a useful lens is 500 nm and, thus, the dry coating thickness must be substantially less than
200 nm to achieve an acceptable surface roughness while maintaining desired
wettability.
Examples 10-13
The silicone hydrogel lens material of Example 1 produced lenses
with a water content of approximately 31 percent. Another similar lens
formulation, with a water content of 39 % , is as follows:
The remainder of the formulation was additives and diluents. The monomer
to diluent ratio was 100:20, the diluent being 3, 7-dimethyl-3-octanol. The
lenses of this material were coated with the 300 kD poly-HEMA coating, but
resulting wettability and surface roughness were unacceptable.
A higher Mw poly-HEMA, containing greater than 1.6 wt percent of
Blue HEMA was synthesized using visible light initiated by CGI 1850 and
the resultant polymer had a Mw of > 1,000,000. A mixture of 900 mg blue
HEMA, 44.1 g HEMA, 615 mg CGI 1850 and 150 mL ethylene glycol was
stirred until homogeneous and the system was degassed as described in
Examples 2-5. The mixture was transferred to a large crystallizing dish and
covered with a watch glass. Polymerization of the olefinic moieties was
conducted under visible light for approximately 1 hour. Upon quenching of
the polymerization using oxygen, the mixture was poured into 500 mL
borate-buffered saline solution and stirred for several hours until the material
was transformed into a more rigid form. The liquids were decanted and the
product washed with another 500 mL borate-buffered saline solution. The
polymer was cut into several smaller pieces and stirred in 500 mL deionized
water for more than 1 hour to the point that the product becomes gel-like and
was sparingly soluble in the solvent. The mixture was then diluted with a
small quantity of borate-buffered saline solution to enable better precipitation
of the polymer. The mixture was filtered and washed in deionized water
until the material did not appear soluble. The suspension was filtered, dried
in a rotary evaporator, cut into smaller pieces and further dried until it
appeared crystalline and anhydrous. The dark blue polymer was then milled
into fine particles and subjected to more deionized water washings
accompanied by 1 to 2 hours of stirring with each wash. Washing continued
until little or no blue color was visible in solution and the product was
filtered, dried at reduced pressure, and ground in a blender. The Mw of this
coating polymer was measured to be 1.2 million g/mol using GPC and a 2 %
solution of the polymer in a 1:1 ethanolrethyl lactate solvent had a viscosity
of 17.7 cP at 25°C at a shear rate of 40/s.
This coating was used to coat TOPAS 5013 molds via spin coating
according to the following procedure. Solutions of the polymer from 0.5 to 2
wt percent by steps if 0.5 wt percent were dissolved in a mixed solvent
system of 1 part ETOH and 1 part ethyl lactate. The coating was applied to
the molding surface of the mold by dispensing the solution onto the center of
a part spinning at approximately 6000 rpm and allowing the part to spin for 5
sec. before stopping. Lenses were made with these coated molds using the
above-described lens material and a dwell time of 30 sec. On Table 5 is
shown the wettability and surface roughness of the resulting lenses.
The results show that changing the dry film thickness can simultaneously
achieve acceptable wettability and surface roughness.
Example 14
High Mw blue poly-HEMA coated silicone hydrogel lenses with the
formulation listed on Table 6 were formed.
The remainder of the formulation were additives and diluents. The monomer
to diluent ratio was 100:20, the diluent being 3,7-dimethyl-3-octanol. Acetic
acid, 1 % of the final mix, was used to stabilize the monomer.
TOPAS 5013 front and back curve molds were coated with a 1.25 wt
percent solution of blue-poly-HEMA and lens made as described in
Examples 10 -13. Excess coating accumulated near the edge of the front
surface mold was removed using a cloth swab during the spinning process.
The lenses were tested for wettability and surface roughness prior to
clinical evaluation. Mean peak-to-peak front surface roughness was 291 nm
and mean advancing contact angle was 83º. Five lenses of -0.50 diopter
power were fit in a contra-lateral study for a 30 min. wear schedule. The lens
surface was equivalent in on-eye wettability, or tear break-up time, and
deposition resistance to ACUVUE® etafilcon A lenses demonstrating that
application of the coating to the lens results in a physiological compatible
lens.
We Claim:
1. A method for manufacturing an article comprising the steps of:
a) coating a molding surface of a mold or a mold half with a
coating effective amount of a high molecular weight coating
composition comprising at least one polymer selected from the
group consisting of poly(vinyl alcohol), polyethylene oxide,
poly(2-hydroxyethyl methacrylate), poly(acrylic acid),
poly(methacrylic acid), poly(maleic acid), poly(itaconic acid),
poly(acrylamide), poly(dimethylacrylamide),
carboxymethylated polymers, polystyrene sulfonic acid,
polysulfonate polymers, polysaccharides, glucose amino
glycans, block or random copolymers thereof, or mixtures
thereof;
b) dispensing a monomer mixture comprising, a silicone-
containing hydrogel monomer, into the mold or mold half; and
c) curing the monomer mixture and the coating composition using
a dwell time of less than about 5 minutes and under conditions
suitable to form an article coated with the coating composition.
2. The method as claimed in claim 1, wherein the article is a contact
lens.
3. The method as claimed in claim 1 or 2, wherein the monomer
mixture comprises a hydrogel.
4. The method as claimed in claim 1 or 2, wherein the monomer
mixture comprises a silicone hydrogel monomer.
5. The method as claimed in claim 1, wherein the molecular weight
of the coating composition is greater than about 300 kD.
6. The method as claimed in claim 1, wherein the dwell time is less
than about 45 seconds.
7. The method as claimed in claim 5, wherein the dwell time is less
than about 45 seconds.
8. The method as claimed in claim 1, wherein the coating
composition further comprises a low boiling point solvent and a
high boiling point solvent.
9. The method as claimed in claim 8, wherein the coating of the
molding surface is carried out by spin coating.
10. The method as claimed in claim 9, wherein spin coating is carried
out using at least about 2 µl and no more than about 20 µl of the
coating composition.
11. The method as claimed in claim 10, further comprising applying,
subsequent to the spin coating step, a pressurized air jet to an edge
of the mold.
12. An article formed by the method as claimed in claim 1, 6, 7 or 9.
13. A contact lens formed by the method as claimed in claim 2.
14. The method as claimed in claim 1, wherein the article is a contact
lens.
15. The method as claimed in claim 14, wherein the monomer mixture
comprises a hydrogel monomer.
16. The method as claimed in claim 14, wherein the monomer mixture
comprises a silicone hydrogel monomer.
17. The method as claimed in claim 1, wherein the dwell time is less
than about 45 seconds.
18. The method as claimed in claim 16, wherein the silicone hydrogel
monomer mixture comprises a reaction product of a silicone based
macromer Group Transfer Polymerization product and a
polymerizable mixture comprising Si8-10 monomethacryloxy
terminated polydimethyl siloxane, polydimethylsiloxane other than
Si8-10 monomethacryloxy terminated polydimethyl siloxane, and a
hydrophilic monomer.
19. The method as claimed in claim 18, wherein the silicone hydrogel
monomer mixture comprises the macromer in an amount of about
15 to about 25 wt%, the Si8-10 monomethacryloxy terminated
polydimethyl siloxane in an amount of about 20 to about 30 wt%;
methacryloxypropyl tris(trimethyl siloxy) silane in an amount of
about 15 to about 25 wt%; N,N-dimethyl acrylamide in an amount
of about 20 to about 30 wt%; 2-hydroxy ethyl methacrylate in an
amount of about 2 to about 7 wt%; tetraethyleneglycol
dimethacrylate in an amount of about 0 to about 5 wt% and
poly(N-vinyl pyrrolidinone) in an amount of about 0 to about 5
weight percent.
20. The method as claimed in claim 1, 14, 15, 16, 17, 18 or 19 wherein
the coating composition comprises poly(vinyl alcohol),
polyethylene oxide, poly(2-hydroxyethyl methacrylate),
poly(acrylic acid), poly(methacrylic acid), poly(maleic acid),
poly(itaconic acid), poly(acrylamide), poly(dimethylacrylamide),
carboxymethylated polymers, polystyrene sulfonic acid,
polysulfonate polymers polysaccharides, glucose amino glycans,
block or random copolymers thereof, or mixtures thereof.
21. The method as claimed in claim 20, wherein the coating
composition comprises poly(2-hydroxyethyl methacrylate).
22. The method as claimed in claim 14, wherein the coating
composition further comprises a low boiling point solvent and a
high boiling point solvent.
23. The method as claimed in claim 22, wherein the coating of the
molding surface is carried out by spin coating.
24. The method as claimed in claim 23, wherein spin coating is carried
out using at least about 2 µl and no more than about 20 µl of the
coating composition.
25. The method as claimed in claim 24, further comprising applying,
subsequent to the spin coating step, a pressurized air jet to an edge
of the mold.
26. An article formed by the method as claimed in claim 1.
27. A contact lens formed by the method as claimed in claim 14, 17,
18 or 19.
28. A contact lens formed by the method as claimed in claim 20.
29. A contact lens formed by the method as claimed in claim 21.
30. The method as claimed in claim 1, wherein the monomer mixture
comprises hydrogel monomer.
31. The method as claimed in claim 1, wherein the monomer mixture
comprises silicone hydrogel monomer.
32. The method as claimed in claim 31, wherein the silicone hydrogel
monomer mixture comprises a reaction product of a silicone based
raacromer Group Transfer Polymerization product and a
polymerizable mixture comprising Si8-10 monomethacryloxy
terminated polydimethyl siloxane, polydimethylsiloxane other than
Si8-10 monomethacryloxy terminated polydimethyl siloxane, and a
hydrophilic monomer.
33. The method as claimed in claim 32, wherein the silicone hydrogel
monomer mixture comprises the macromer in an amount of about
15 to about 25 wt%, the Si8-10 monomethacryloxy terminated
polydimethyl siloxane in an amount of about 20 to about 30 wt%;
methacryloxypropyl tris(trimethyl siloxy) silane in an amount of
about 15 to about 25 wt%; N,N-dimethyl acrylamide in an amount
of about 20 to about 30 wt%; 2-hydroxy ethyl methacrylate in an
amount of about 2 to about 7 wt%; tetraethyleneglycol
dimethacrylate in an amount of about 0 to about 5 wt% and
poly(N-vinyl pyrrolidinone) in an amount of about 0 to about 5
weight percent.
34. The method as claimed in claim 1, 30, 31, 32 or 33 wherein the
coating composition comprises poly(vinyl alcohol), polyethylene
oxide, poly(2-hydroxyethyl methacrylate), poly(acrylic acid),
poly(methacrylic acid), poly(maleic acid), poly(itaconic acid),
poly(acrylamide), poly(dimethylacrylamide), carboxymethylated
polymers, polystyrene sulfonic acid, polysulfonate polymers
polysaccharides, glucose amino glycans, block or random
copolymers thereof, or mixtures thereof.
35. The method as claimed in claim 34, wherein the coating
composition comprises poly(2-hydroxyethyl methacrylate).
36. The method as claimed in claim 34, wherein the coating
composition further comprises a low boiling point solvent and a
high boiling point solvent.
37. The method as claimed in claim 36, wherein the coating of the
molding surface is carried out by spin coating.
38. The method as claimed in claim 37, wherein spin coating is carried
out using at least about 2 µl and no more than about 20 µl of the
coating composition.
39. The method as claimed in claim 24, further comprising applying,
subsequent to the spin coating step, a pressurized air jet to an edge
of the mold.
40. A contact lens formed by the method as claimed in claim 1, 30, 31,
32 or 33.
41. A contact lens formed by the method as claimed in claim 34.
42. A contact lens formed by the method as claimed in claim 35.
43. A contact lens formed by the method as claimed in claim 36.
44. A contact lens formed by the method as claimed in claim 37.
45. The contact lens as claimed in claim 40, wherein the coating
composition comprises a coating of a dry film thickness of not less
than about 5 nm and not more than about 70 run.
46. The contact lens as claimed in claim 41, wherein the coating
composition comprises a coating of a dry film thickness of not less
than about 5 nm and not more than about 70 nm.
47. The contact lens as claimed in claim 44, wherein the coating
composition comprises a coating of a dry film thickness of not less
than about 5 nm and not more than about 70 run.
48. The contact lens as claimed in claim 43, wherein the coating
composition comprises a coating of a dry film thickness of not less
than about 5 nm and not more than about 70 nm.
49. The contact lens as claimed in claim 4, wherein the coating
composition comprises a coating of a dry film thickness of not less
than about 5 nm and not more than about 70 nm.
A method for manufacturing an article comprising the steps of: coating a
molding surface of a mold or a mold half with a coating effective amount of
a high molecular weight coating composition comprising at least one
polymer selected from the group consisting of poly(vinyl alcohol),
polyethylene oxide, poly(2-hydroxyethyl methacrylate), poly(acrylic acid),
poly(methacrylic acid), poly(maleic acid), poly(itaconic acid),
poly(acrylamide), poly(dimethylacrylamide), carboxymethylated polymers,
polystyrene sulfonic acid, polysulfonate polymers, polysaccharides, glucose
amino glycans, block or random copolymers thereof, or mixtures thereof;
dispensing a monomer mixture comprising, a silicone-containing hydrogel
monomer, into the mold or mold half; and curing the monomer mixture and
the coating composition using a dwell time of less than about 5 minutes and
under conditions suitable to form an article coated with the coating
composition.

Documents:


Patent Number 222900
Indian Patent Application Number 189/KOLNP/2004
PG Journal Number 35/2008
Publication Date 29-Aug-2008
Grant Date 27-Aug-2008
Date of Filing 12-Feb-2004
Name of Patentee JOHNSON & JOHNSON VISION CARE, INC.
Applicant Address 7500 CENTURION PARKWAY, SUITE 100, JACKSONVILLE, FLORIDA
Inventors:
# Inventor's Name Inventor's Address
1 DAVID TURNER C 12159 TRAVERTINE TRAIL, JACKSONVILLE, FL 32223
2 SHIVKUMAR MAHADEVAN RT. 1 BOX 759, STARKE, FL 32091
3 FRANK MOLOCK F 1643 WILDFERN DRIVE, ORANGE PARK, FL 32073
4 KEVIN MCCABE P 9087 STARPASS DRIVE, JACKSONVILLE, FL 32256
5 DHARMESH K. DUBEY 9087 STARPASS DRIVE, JACKSONVILLE, FL 32256
6 JEFFERY LONGO S 7068 HOLIDAY HILL COURT, JACKSONVILLE, FL 32215
7 JONATHAN P. ADAMS 11474 SHADY MEADOWS DRIVE, JACKSONVILLE, FL 32215
8 ANDREW J. WAGNER 1316 PINE BLOOM COURT, JACKSONVILLE, FL32259
9 XIOPING LIN 8980 ADAMS WALK DRIVE, JACKSONVLLE, FL 32257
10 LENORA C. COPPER 12306 PEACH ORCHARD DRIVE, JACKSONVILLE, FL 32205
11 DOMINIC GOURD 8090 ATLANTIC BOULEVARD, JACKSONVILLE, FL 32211
PCT International Classification Number B29C 39/08
PCT International Application Number PCT/US02/24022
PCT International Filing date 2002-07-29
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 09/921,192 2001-08-02 U.S.A.