Note: Descriptions are shown in the official language in which they were submitted.
~27~427
PHOTOCHROMIC PLASTIC ARTICLE AND METHOD FOR PREPARING SAM~
Description of the Invention
The present invention relates to photochromic synthetic plastic
articles, particularly photochromic optical elements, such as lenses.
More particularly, the present invention relates to a method for prepar-
ing photochromic synthetic plastic articles. Photochromism is a revers-
ible phenomenon illustrated by a compound which, when exposed to ultra-
violet irradiation, changes color and subsequently reverts to its origi-
nal color or state upon removal of the initial source of ultraviolet
irradiation. A compound illustrating this property is called a photo-
chromic compound.
Several approaches have been used to incorporate photochromic
compounds into a synthetic plastic host material. For example, U.S. Pat-
ent 3,212,898 describes preparing a photosensitive composition by suspend-
ing a photochromic benzospiropyran in a preformed polyester resin. U.S.
Patent 3,666,352 describes dispersing a mercury thiocarbazone compound in
a solidified plastlcized vinyl chloride-vinyl acetate copolymer, which
copolymer is laminated between two plastic or glass layers, thereby to
form a photochromic sunglass lens.
U.S. Patent 3,508,810 describes preparing a safety glass unit
by incorporating a photochromic mercury dithizonate or benzospiropyran
compound into the polyvinyl butyral film sealed between the two glass
plates of the unit. In one embod~ment, a glass plate is coated with the
44;~7
photochromic benzospiropyran compound and the polyvinyl butyral plastic
film placed over the photochromic coating. A second piece of glass of
placed on top of the polyvinyl butyral film and the composite structure
cured in an autoclave at 275F. (135C.) and a pressure of 150 pounds per
square inch gauge (1034 kPa). Similarly, U.S. Patent 3,522,143 describes
milling or mixing a photochromic metal dithizonate compound into the film
before sheeting or applying the photochromic compound as a coating onto
one of the surfaces of the film to provide a material suitable for use as
a lamina or interlayer in a laminated safety glass unit.
U.S. Patent 4,173,672 describes a decorated safety glass com-
prising two glass sheets joined by a decorated film of a thermoplastic
polymer, e.g., a polyvinyl butyral film. The thermoplastic polymer is
decorated by transferring a colored impression to it from a temporary
cellulosic support sheet~ e.g., a printed paper bearing a color impres-
sion formed of organic or inorganic colorants, by heat and pressure.
Subsequently, the temporary cellulosic support sheet is removed and a
second sheet of glass placed over the decorated thermoplastic film. The
two glass sheets and the interposed decorated film is sub~ected to heat
and pressure until the organic or inorganic colorant becomes impregnated
into the interposed thermoplastic film.
U.S. Patent 4,268,134 describes interposing a photochromlc
glass sheet between two layers of optically clear plastic to produce a
light-weight laminated photochromic lens. U.S. Patent 4,289,497
describes a gradient photochromic lens in which the photochromic material
is imbibed intothesynthetic plastic lens by immersion of the lens into
a solution of the photochromic compound.
U.S. Patent 4,286,957 utili~es the conventional "thermal trans-
fer" technique to integrate a photochromic material into a synthetic
. ~.
~2'~44~7
organic polymer host material. In this technique, the photochromic com-
pound is applied to the surface of the organic host and then heated at
between 180C. and 220C. for from 30 to 45 seconds to integrate by ther-
mal transfer the photochromic material into the host material. It
appears from published melting ranges of several of the benzospiropyrans
described in that patent that the reported heating temperatures of
180C.-220aC.is above the melting temperature of such benzospiropyran
material.
The present invention resides in the discovery of a combination
of process steps that yield an expedient method for incorporating photo-
chromic compound(s) into a synthetic plastic material. In an embodiment
of this process, a relatively thin, substantially dry homogeneous film
containing a photochromic substance dissolved in a carrier polymeric resin
is applied to at least one surface of the synthetic plastic material.
The photochromic substance is then incorporated into the plastic material
by heating the resin film substantially uniformly at temperatures below
the melting temperature of the photochromic substance. Subsequently, the
resin film depleted of photochromic substance is removed from the surface
of the plastic material.
The aforesaid method permits the preparation of photochromic
plastic films, sheets and castings useful in optical applications such as
sunglasses, ski goggles, visors, camera lenses, optical filters, lens
blanks, automotive windshields and ophthalmic lenses. As used herein,
the term "optical element" is meant to include lenses and transparencies.
DETAILED DESCRIPTION OF THE INVENTION
In accordance with an embodiment of the present process, a
thin, substantially dry homogeneous film of polymeric organic resin having
lX744~7
a photochromic substance, e.g., a spiro(indoline)-type photochromic
compound, dissolved therein is applied to at least one principal surface,
e.g., a substantially planar surface, of a synthetic plastic host mate-
rial. The plastic material to which the film is applied may be substan-
tially flat or may have some degree of curvature, such as the convex
and/or concave surfaces of a lens. As used herein, the terms "principal
surface" or "planar surface" are intended tc refer to that surface or
those surfaces (flat or curved) of the plastic host material other than
the side corresponding to the thickness of the plastic host. Preferably,
the film is applied to at least one and, more preferably, to both princi-
pal surfaces of a substantially flat, preformed synthetic plastic host
material.
Application of the photochromic-containing resin film to the
receptor surface is by a technique which produces a substantially dry,
substantially mottle-free film or coating of substantially uniform thick-
ness. By substantially mottle-free i9 meant that the film is substan-
tially free of droplets, ridges, streaks, blotches, spots etc. of solidi-
fied resin produced by non-uniformity in film thickness or uneven solvent
removal. The thickness of the film is not critical but will commonly be
between about 0.5 and 3.0 mils (0.0005-0.003 inches), e.g., 1-2 mils.
The film should be sufficiently thin to enable the photochromic substance
to move from the film and permeate or diffuse readily into the interior
of the plastic host material, thereby to produce a plastic article
exhibiting a photochromic response, i.e., exhibiting a change in
transmission upon exposure to ultraviolet irradiation, which change in
transmission (color change) can be visualized. If the film is too thick,
the temperature and time required to transfer a photochromic amount of
photochromic substance to the plastic host may be excessive and cause
~2744~7
decomposition of the photochromlc substance. Further, a relatively sig-
nificant amount of the photochromic substance will remain in the thick
film, which adds an adverse economic burden to the process by loss of the
photochromic substance or by adding the cost of recovering it from the
spent film.
The amount of photochromic material required to achieve a
visual photochromic response in the plastic host, i.e., a photochromic
amount, can vary and will generally depend upon the intensity of the
color change desired upon ultraviolet irradiation of the treated plastic
article and the photochromic material used. The greater the desired
change in color intensity, the greater the amount of the photochromic
material required. Typically, a photochromic response may be achieved
when the amount of the photochromic material dispersed within the plastic
host is from about 0.2 to 1 milligram per square inch, based on the area
o one planar surface. Generally, the photochromic substance will be
present in the resin solution in amounts of between about 1.0 and 5
weight percent, more commonly between about 1.5 and 3.5 weight percent.
Expressed differently, the photochromic substance will, in a preferred
embodiment, constitute between about 25 and 40 weight percent, more pref-
erably between 30 and 35 weight percent, o the dried solid resin film.
It i8 also contemplated that different surfaces or even different parts
or portions of the same surface may have different film thicknesses
and/or different concentrations of photochromic substances to thereby
vary the intensity of the color change in different portions of the plastic
host.
The polymeric resin used to form the film on the surface of the
plastic host material serves as a solvent for the photochromic substance,
e.g., a spiro(indoline)-type photochromic material such as a spiro(indo-
- 5~-
~74~;~7
line)naphthoxazine. The affinity between the carrier resin and photo-
chromic substance, i.e., the solubility of the photochromic compound in
the carrier resin, should preferably not be high but sufficient to form a
homogeneous solution at the above-described concentrations, i.e., the
photochromic compound should be only slightly to moderately soluble in
the resin so as to permit ready removal of the photochromic compound from
the resin film. If, for example, the photochromic substance is infinite-
ly, i.e., highly, soluble in the resin, the driving force required to
transfer the photochromic material to the plastic host would be higher
than if the photochromic substance were slightly or moderately soluble in
the resin. Further, the efficiency of the transfer, i.e., the amount of
photochromic substance transferred (basis the total amount in the resin)
would be lower. Moreover, increasing the temperature of transfer to
attain higher transfer efficiencies may promote pyrolysis of the photo-
chromic substance. The resin should, however, have sufficient affinity
for the photochromic compound to achieve a concentration of the
photochromic compound of, for example, from Z5-40 weight percent in the
dried resin film without crystallization or segregation of the
photochromic compound in the dried film. If the photochromic compound is
too insoluble in the resin, it will crystallize out of the resin and form
localized concentrations or islands in the solid resin film, i.e., form a
non-homogeneous coating. Such an occurrence results in a mottled film
and the non-uniform transfer of photochromic compound into the plastic
article, thereby resulting in the article exhibiting a non- uniform color
density - a result which is undesirable. Similarly, the resin should not
adhere strongly to the synthetic plastic host material to which it is
applied so that it can be readily removed from the surface of the plastic
without leaving any marks on the surface. The resin should also remain
solid and not become liquid at the temperature at which the photochromic
substance is transferred.
~74~;~7
Examples of suitable polymeric resins that can be used to form
the above~described film are: polyvinyl chloride, polyvinylacetate, poly-
urethanes, polyvinylbutyral, copolymers of vinyl chloride and vinyl ace~
tate, copolymers of vinyl chloride and vinylidene chloride, polyvinyl
propionate, cellulose acetate butyrate, polymerizates of the lower alkyl
(Cl-C4), e.g., methyl, ethyl, n-butyl and isobutyl, esters of acrylic
and methacrylic acid such as polymethylacrylate, polymethylmethacrylate
and polymethyl/butyl methacrylate and mixtures of polyvinyl chloride and
the aforesaid polyacrylates, e.g., mixtures of from about 90 parts of
polyvinyl chloride and 10 parts of polymethylmethacrylate to about 10
parts of polyvinyl chloride and 90 parts of polymethylmethacrylate.
The photochromic-containing resin is applied to the surface of
the plastic host by means resulting in a substantially dry coating 80 as
to obtain a substantially mottle-free coating. The photochromic-resin
carrier medium generally comprises a solution of the photochromic-bearing
resin in an organic solvent(s) that is readily volatile at ambient temper-
atures, e.g., room temperatures (20-22C.). Preferably, the solvent is
colorless. The solution generally comprises between about 1 and S weight
percent of the photochromic substance9 between about 2 and 10 weight per-
cent of the resin and between about 85 and 97 weight percent of solvent.
Preferably, the solution comprises between about 1.5 and about 3.5 weight
percent of the photochromic material, between about 3 and 7 weight per-
cent of the resin and between about 89.5 and 9S.S percent of solvent.
Examples of readily volatile or vaporizable solvents include
toluene, benzene, xylene, methylethylketone, methylisobutylketone, methyl-
chloroform, acetonitrile, tetrahydrofuran, dioxane, cyclohexanone, ethyl
acetate, propyl acetate, isopropyl acetate, isobutyl acetate, butyl ace-
tate, methyl alcohol, ethyl alcohol, butanol, isopropanol, 2-methoxy-
-- 7 --
1~744;~7
ethanol, acetone, and mixtures of such solvents~ Preferably, the solventis selected from toluene, methylethylketone, methylisobutylketone and
mixtures of such solvents.
The solution of photochromic material, resin and solvent can be
prepared by any convenient technique, e.g., by dissolving independently
the resin and photochromic substance in appropriate solvents. The result-
ing two solutions can then be mixed to produce the solution of
photochromic-bearing resin used to apply the coating to the surface of
the plastic host.
The above-described solution of photochromic-bearing resin mate-
rial is applied to at least one principal surface, e.g., a substantially
flat surface, of the film-receiving surface of the plastic host by tech-
niques known in the art that are suitable to produce a substantially
mottle-free coating or film of substantially uniform thickness. Prefera-
bly, the solution is applied in such a manner that the resulting film is
substantially dry as soon as it is formed, i.e., the readily vaporizable
solvent is substantially volatilzed as the resin is applied to the recep-
tor surface of the plastic host, thereby leaving a substantially dry
film. Application techniques that may be employed include spraying,
brushing, spin-coating, dip coating and use of a draw-down blade or wire
bar. Of the aforesaid techniques, spraying ls preferred. Sprsying
allows for good solvent release from the atomized droplets of the solu-
tion which, in a preferred mode, has a viscosity of about 1 to 20, e.g.,
5, centipoises. The viscosity of the spray solution will depend on its
constituents and the amount of each used. More preferably, the viscosity
of the solution is in the lower portion of the aforesaid range, e.g., l
to 10 centiposes.
~744~
Spraying also permits the controlled application of a thin coat-
ing of substantially uniform thickness~ Thickness and uniformity of the
film can be controlled by the number of times the surface is sprayed and
the shape of the spray exiting the spray gun. Preferably, from two to
six coverages of the sprayed solution over the receptor surface are used
in producing a relatively thin film of substantially uniform thickness
and composition, i.e., a homogeneous film. The high surface area of the
atomized solution achieved with the spray technique provides for ready
evaporization of the solvent so that the film is substantially dry at the
instant of application to the surface of the plastic host. This avoids
the formation of droplets, streaks, blotches, spots or other imperfec-
tions when the applied film is still in liquid form.
Before applying the solution of photochromic-bearing resin to
the plastic host, the surface of the plastic to which the resin is to be
applied is preferably cleaned. Cleaning may be accomplished by washing
the surface with an aqueous medium, e.g., soapy water, to remove dust and
dirt; washing the surface with an organic solvent such as methylchloro-
form or methylethylketone to remove any organic film present on the sur-
face; and/or eliminating static charges that are present on the surface
of the plastic material. Elimination of static electricity can be accom-
plished by commércially available equipment which ionize the air above
the surface, thereby producing a conductive path which allows the static
charge to drain off or otherwise be neutralized.
The surface of the plastic material to which the resin is
applied should be receptive to imbibition of the photochromic substance
during the heating step. If the receptor surface is not amenable to imbi-
bition, it can be treated to permit improved diffusion of the photo-
chromic substance into the subsurface of the plastic host, e.g., by
1~74~7
physically or chemically etching the surface. A receptive surface can be
achieved usually by undercuring slightly the plas~ic during its forma-
tion, or by addition of a plas~icizeL- to the monomeric materialts) used
to prepare the organic plastic host. Such techniques are conventional in
the polymerization art.
Following application of the photochromic-bearing resin film to
the surface(s) of the plastic host material, the substantially dry film
is permitted to completely dry. Drying can be conveniently conducted at
room temperature in air; but, other conditions of drying which avoid
crystallization of the photochromic compound within the resin film may be
used as the occasion warrants. Thereafter, the coated plastic article is
heated substantially uniformly at temperatures below the melting tempera-
ture of the photochromic compound used. Heating can be accomplished by
any convenient technique which results in substantially uniform heating
of the film and plastic host. Preferably, heating is accomplished in a
conventional hot air recirculating oven, which allows for uniform heating
and hence a constant driving force for transfer of the photochromic com-
pound into the plastic host. Heating may also be accomplished in a vacuum
or with use of an inert, e.g., nitrogen atmosphere.
The temperatures to which the coated plastic article is heated
wlll vary and depend on the melting temperature and vapor pressure of the
particular photochromic compound utilized as well as the softening temper-
ature of the synthetic plastic article. Such temperatures should prefer-
ably be near to but below the melting temperature of the photochromic
compound and below the softening temperature of the synthetic plastic
article. Moreover, such temperatures, i.e., photochromic transfer or
incorporation temperatures, should be such as to minimiæe decomposition
(pyrolysis) of the photochromic compound. Hence, the transfer temperatures
-- 1~ --
~27~
chosen are sufficient to raise the vapor pressure of the photochromic
compound adequately to permit its transfer to the plastic host without
significant decomposition of the compound and softening of the plastic
host. As the melting temperatures and vapor pressures of photochromic
compounds, e.g., spiro(indoline)-type photochromic compounds, will
vary depending on the nature of the compound and its substituents,
one temperature range applicable to all photochromic materials cannot be
described. However, given the above requirements one skilled in the art
can readily determine an appropriate temperature for heating the cGated
plastic article. Transfer temperatures of between about 5C. and about
50C., preferably between 5C. and 10C., less than the melting tempera-
ture of the photochromic compound are contemplated except where signifi-
cant decomposition of the photochromic compound is experienced at such
temperatures. Generally, temperatures contemplated for use in associa-
tion with spiro(incloline)naphthoxazine and with spiro(indoline)pyrido
benzoxazine photochromic compounds are between about 145C. and about
160C. More particularly, for the photochromic compounds: 1,3,3,5,6-
pentamethyl-a'-methoxyspiro[indolino-2,3'[3H]-naphtho [2,1-b] [1,4]-
oxazine]; 1,3,5,6-tetramethyl-3-ethylspiro[indoline-2,3'[3H] pyrido
[3,2-f] [1,4]-benzoxazine]; and 1,3,3,4,5-(or 1,3~3,5,6-)pentamethylspiro
[indoline-2,3' [3H] pyrido [3,2-f] [1,4] benzoxazine], temperature~ of
between about 145C. and about 155C., e.g., 150-155C., are contemplated.
The coated plastic article is maintained at the above-described
transfer temperatures, for a time sufficient to allow a substantial por-
tion, i.e., a photochromic amount, of the photochromic compound to dif-
fuse into and penetrate beneath the surface of the plastic article. Typi-
cally, the heating period is from between about 15 minutes and about 60
-- 11 --
1~74~7
minutes, usually between about 20 and about 45 minutes at the transfer
temperatures. For the above-described photochromic benzoxazine com~
pounds, heating for from 25 to 30 minutes is adequate.
The mechanism by which the photochromic compound transfers from
the resin film adhered to the surface of the plastic host into the plas-
tic host material has not been established with certainty. It is postu-
lated that transfer may be accomplished by-thermal diffusion, sublimation
and condensation or a combination of the aforesaid mechanisms. Whatever
the specific mechanism(s), the photochromic compound permeates into the
interior of the plastic substrate, usually into the subsurface regions
thereof, and becomes permanently and solidly incorporated within the plas-
tic host material. In this manner, a photochromic amount of the photo-
chromic substance is transferred substantially uniformly into and across
the planar surface of the plastic host.
Following transfer of the photochromic compound into the plas-
tic article, the coated plastic is allowed to cool, e.g., to room tempera-
ture, and subsequently the residual resin film, its concentration of
photochromic substance reduced, is removed from the surface of the plas-
tic host. Removal of the photochromic compound-depleted film may be
accomplished by any suitable technique; preferably a technique that does
not impair the optical quality of the surface of the plastic. Conveniently,
the depleted film is stripped from the plastic substrate by contacting
the film with a suitable organic solvent such as methylchloroform,
trichloroethylene, methylethylketone, methylisobutylketone,
methylethylketone-toluene mixture, or other solvents such as: acetone,
ethylene dichloride, chloroform and chlorobenzenes. The same solvent
used to prepare the photochromic-bearing resin solution may be used to
remove the residual resin film.
~ 12 -
~274~ 7
A suitable method for contacting the film with organic solvent
is in a vapor degreasing unit wherein the film is exposed to the vapors
of the ~elected solvent(s) which condense on and run off the surface of
the plastic material, thereby washing the photochromic-depleted resin
film from the surface. Al~ernatively, the resin film can be removed by
dipping the plastic substrate into a bath of the solvent, spraying the
solvent of the film or physically stripping the film from the substrate.
After the photochromic compound-depleted or spent film has been
removed from the surface of the plastic article, the surface can be
washed with water or other suitable aqueous medium such as, for example,
soap or detergent solutions and dried. If desired, the plastic article
can be tinted with conventional disperse and soluble dyes used in the
tinting of organic plastic materials uslng techniques well-known in the
art, eOg., a conventional dye bath. Thereafter, the tinted plastic arti-
cle is washed, e.g., with soapy water, and dried. Tinting of the plastic
article can be performed immediately after removal of the spent resin
film and before washing with the aqueous medium. Alternatively, tinting
can be performed before the photochromic compound is applied.
Synthetic plastic host materials that may be utilized in the
process of the present invention are solid, transparent polymerized organ-
ic materials. Preferably, the host material is an optically clear mate-
rial, i.e., material suitable for ophthalmic or optical elements, such as
ophthalmic lenses, or materials useful for such applications as windows,
windshields, etc.
Examples of transparent host materlals which may be used with
the photochromic compounds of the present invention include: polymers
and copolymers of polyol(allyl carbonate) monomers, polyacrylates, poly-
(alkylacrylates) such as polymethylmethacrylates, cellulose acetate, cel-
- 13 -
~74~7
lulose proplonate, cellulose butyrate, cellulose triacetate, cellulose
acetate propionate, cellulose acetate butyrate, poly(vinyl acetate), poly-
(vinyl alcohol), polyurethanes, polycarbonates, polyethyleneterephtha-
late, polystyrene, poly(styrene-methylmethacrylate) copolymers, poly-
(styrene-acrylonitrile) copolymers, polyvinyl pyrrolidone, polyvinyl chlo-
ride, polyvinyl butyrate and polyvinylbutyral. Transparent blends of the
transparent polymers and copolymers are also suitable as host materials.
Preferably, the host material i6 an optically clear polymerized organic
material prepared from a polycarbonate, such as poly(4,4'-dioxydiphenol-
2,2-propane), which is sold under the trademark, LEXAN; a polyol(allyl
carbonate), especially polymers of diethylene glycol bis(allyl carbon-
ate), which is sold under the trademark, CR-39, and its copolymers with,
for example, vinyl acetate, e.g., copolymers of from 80-90 percent di-
ethylene glycol bis(allyl carbonate) and 10-20 percent vinyl acetate,
particularly 80-85 percent of the bis(allyl carbonate) and 15-20 percent
vinyl acetate; cellulose acetate, cellulose propionate, cellulose butyr-
ate; polystyrene and its copolymers with methyl methacrylate, vinyl ace-
tate and acrylonitrile, and cellulose acetate butyrate. Polymethylmeth-
acrylate, such as the material sold under the trademark, PLEXIGLAS may
also be used with photochromic substances having melting points les6 than
about 140C.
Polyol (allyl carbonate) monomers which may be polymerized to
form a transparent host material are the allyl carbonates of linear or
branched aliphatic or aromatic liquid polyols, e.g., aliphatic glycol
bis(allyl carbonate) compounds, or alkylidene bisphenol bis(allyl carbon-
ate) compounds. These monomers can be described as unsaturated polycar-
bona~es of polyols, e.g., glycols. The monomers can be prepared by proce-
dures well known in the art, e.g., U.S. Patents 2,370,567 and
2,403,113.
~Z74~7
The polyol (allyl carbonate) monomers can be represented by the
graphic formula:
R ~ O - C - O - R)
wherein R is the radical derived from an unsaturated alcohol and is com-
monly an allyl or substituted allyl group, R' is the radical derived from
the polyol, and n is a whole number from 2 - 5, preferably 2. The allyl
group (R) can be substituted at the 2 position with a halogen, most
notably chlorine or bromine, or an alkyl group containing from 1 to 4
carbon atoms, generally a methyl or ethyl group. The R group can be
represented by the graphic formula:
1o
H2C = C - CH2 - II
wherein R is hydrogen, halogen, or a C1-C4 alkyl group. Specific
examples of R include the groups: allyl, 2-chloroallyl, 2-bromoallyl,
2-fluoroallyl, 2-methallyl, 2-ethylallyl, 2-isopropylallyl, 2-n-propyl-
allyl, and 2-n-butylallyl. Most commonly, R is the allyl group, H2C =
CH - CH2-.
R' is a polyvalent radical derived from the polyol, which can
be an aliphatic or aromatic polyol that contains 2, 3, 4 or 5 hydroxy
groups. Typically, the polyol contains 2 hydroxy groups, l.e., a glycol
or bisphenol. The aliphatic polyol can be linear or branched and contain
from 2 to 10 carbon atoms. Commonly, the aliphatic polyol is an alkylene
glycol having from 2 to 4 carbon atoms or a poly(C2-C4) alkylene gly-
col, i.e., ethylene glycol, propylene glycol, trimethylene glycol, tetra-
methylene glycol, or diethylene glycol, triethylene glycol, etc.
The aromatic polyol can be represented by the graphic formula:
- 15 -
~2744~
OH OH
(Ra)p ~ A ~ _ (Ra)p III
wherein A is a bivalent radical derived from an acyclic aliphatic hydro-
carbon, e.g., an alkylene or alkylidene radical, having from 1 to 4 car-
bon atoms, e.g., methylene, ethylene, dimethylmethylene (isopropylidene),
Ra represents lower alkyl substituents of from 1 to 3 carbon atoms, and p
is the integer 0, 1, 2, or 3. Preferably, the hydroxyl group is in the
ortho or para posltion.
Specific examples of the radical R' include: alkylene groups
containing from 2 to 10 carbon atoms such as ethylene (-CH2-CH2-),
trimethylene, methylethylene, tetramethylene, ethylethylene, penta-
methylene, hexamethylene, 2-methylhexamethylene, octamethylene, and
decamethylene; alkylene ether groups such as -CH2-O-CH2-, -CH2CH2-O-CH2CH2-,
-CH2-O-CH2-CH2-, and -CH2CH2CH2-O-CH2CH2CH2-; alkylene polyether groups
2 2 2 2 CH2CH2- and -CH2CH2CH2-O-CH CH CH O CH CH
alkylene carbonate and alkylene ether carbonate groups such as -CH2CH2-O-CO-O-CH2CH2-
and -CH2CH2-O-CU2CH2-O-CO-O-CH2CH2-O-CH2CH2-; and isopropylidene bis(para-phenyl),
i.e., ~ C ~ IV
Most commonly, Rl is -CH2CH2-, -CH2CH2-O-CH2CH2-, or
-cH2cH2-o-cH2cH2-o CH2 2
- 16 -
~744~
Specific examples of polyol (allyl carbonate) monomers include
ethylene glycol bis(2-chloroallyl carbonate), ethylene glycol bis(allyl
carbonate), diethylene glycol bis(2-methallyl carbonate) 3 diethylene gly-
col bis(allyl carbonate), triethylene glycol bis(allyl carbonate), propyl-
ene glycol bis(2-ethylallyl carbonate), 1,3-propanediol bis(allyl carbon-
ate), 1,3-butanediol bis(allyl carbonate), 1,4-butanediol bis(2-bromo-
allyl carbonate), dipropylene glycol bis(allyl carbonate), trimethylene
glycol bis(2-ethylallyl carbonate), pentamethylene glycol bls(allyl car-
bonate), and isopropylidene bisphenol bis~allyl carbonate).
Industrially important polyol bis(allyl carbonate) monomers
which can be utilized in the invention herein contemplated are:
O O
Il 11
CH2 = CH-cH2-o-c-o-cH2cH2-o-cH2cH2-o-cH2cH2-o-c-o-cH2-cH = CH2, ~r
Triethylene Glycol bis(Allyl Carbonate)
O O
Il 11
CM = CH-CH O-C-O-CH2CH2-0-CH2CH20-c-o CH2 2 ~II
Diethylene Glycol bis(Allyl Carbonate)
O O
CH = CH-Cl~2-0-C-O-CH2C~2-~-C-o C1l2 2 VII
Ethylene Glycol bis(Allyl Carbonate)
Diethylene glycol bis(allyl carbonate) is preferred.
Because of the process by which the polyol(allyl carbonate)
monomer ls prepared, i.e., by phosgenation of the polyol (or allyl alco-
hol) and subsequent esterification by the allyl alcohol (or polyol)
- 17 -
~ ~74~;~7
respectively, the monomer product can contain related species in which
the moiety connecting the allyl carbonate groups contains one or more
carbonate groups. These related species can be represented by the graph-
ic formula:
O O
li 11
R-O-C-[O~~ -~C~]s~~ VIII
wherein R is as defined above, Rb is a bivalent radical, e.g., alkylene
or phenylene, derived from a diol, and s is a whole number from 2 to 5.
The related species of diethylene glycol bis(allyl carbonate) can be rep-
resented by the graphic formula,
O O
CH2 = CH-CH2-0-C[-O-CH2CH -O-CH CH _o-lC] -0-CH -CH = CH IX
wherein s is a whole number from 2 to 5. The polyol (allyl carbonate)
monomer can typlcally contain from 2 to 20 weight percent of the relateu
species and such related species can be present as mixtures, i.e., mix-
tures of the species represented by 9 being equal to 2, 3, 4 etc.
Photochromic substances contemplated for use in the process of
the present invention are compounds, including spiro(indoline)-type com-
pounds, that provide a visual photochromic response, are moderately
soluble in the above- described resin carrier, are soluble in the plastic
host, and are readily transferrable to the plastic host from a film on
its surface by tha application of heat without significant decomposition
at temperatures near to but below its melting temperature, as heretofore
described. Particularly contemplated are spiro(indoline)pyrido benzox-
-- 1~ --
~27~4~7
azines, spiro(indoline)naphthoxazines, spiro(indoline)benzopyrans, spiro-
(indoline)naphthopyrans, spiro(indoline)quinopyrans, spiro(indoline)benzo-
xazines, spiro(indoline)pyridopyrans, and spiro(indoline)pyridooxazines
having a molecular weight less than 600, e.g., between about 250 and
450. Preferred are the aforesaid pyrido benzoxazines and naphthox-
azines.
Spiro(indoline)pyrido benzoxazines contempiated herein may be
represented by the following graphic formula:
?r~ X
In the above graphic formula X, R1 is selected from ehe group consist-
ing of hydrogen, C1-C8 alkyl, e.g., methyl, ethyl, propyl, butyl,
etc., phenyl, phen(C1-C4)alkyl, allyl snd mono- and di-substituted
phenyl, said phenyl substituents being selected from C1-C4 alkyl and
C1-C5 alkoxy, e.g., methoxy, ethoxy, propoxy, butoxy and pentoxy.
Preferably, R1 is hydrogen, a Cl-C4 alkyl, phenyl or benzyl
radical.
R2 and R3 of formula X are each selected from the group
consisting of hydrogen, C1-C5 alkyl, phenyl, mono- and di-substituted
phenyl, benzyl or combine to form a cyclic ring selected from the group
consisting of an alicyclic ring containing from 6 to 8 carbon atoms
- 19 -
1~7~4;~7
(including the spiro carbon atom), norbornyl and adamantyl. The phenyl
substituents may be selected from Cl-C4 alkyl and Cl-C5 alkoxy
radicals. Preferably, R2 and R3 are each selected from Cl-C5
alkyl such as methyl and ethyl. When one of R2 or R3 is a tertiary
alkyl radical, such as tertiary butyl or tertiary amyl 9 the other is
preferably an alkyl radical other than a tertiary alkyl radical.
R4 and R5 in graphic formula X are each selected from the
group consisting of hydrogen, Cl-C5 alkyl, halogen, Cl-C5 alkoxy,
nitro, cyano, Cl-C4 haloalkyl, Cl-C4 polyhaloalkyl, and Cl-C8
alkoxycarbonyl. R4 and R5 can be present on any two of the available
carbon atoms of the indolino portion of the compound, i.e., on the 4, 5,
6, or 7 positions. Preferably, when the substituents are other than
hydrogen, they are present at the 4 and 5, 5 and 6, 4 and 7 or 6 and 7
positions. While any halogen, i.e., chlorine, bromine, iodine and fluor-
ine, may be used in respect to the halogen or haloalkyl substituents,
chlorlne, bromine and trifluoromethyl are preferred. Preferably, R4
and R5 are selected from the group consisting of hydrogen, Cl-C2
alkyl, e.g., methyl and ethyl, chlorine, bromine, and Cl-C5 alkoxy,
e.g., methoxy and ethoxy.
Of particular interest, are photochromic compounds represented
by graphic formula X wherein Rl is a Cl-C4 alkyl, such as methyl~
ethyl, n-propyl, isopropyl, n-butyl, secondary butyl, isobutyl and ter-
tiary butyl; R2 and R3 are each methyl, ethyl or phenyl; and R4 and
R5 are each hydrogen, methyl, methoxy, or chloro.
The spiro(indoline)pyrido benzoxazines described above can be
synthesized by reaction of the corresponding nitroso-hydroxy quinoline
compound wlth the corresponding free indoline (Fischer's base) or
indolium salt, e.g., the iodide salt, compound. The two precursor mate-
- 20 -
~74~7
rials are refluxed in a suitable solvent such as toluene or isopropanol
until the reaction is completed. A base, such as triethylamine~ is
present in the reaction medium when the indolium salt is used as the reac-
tant. See, for example, European Patent Application 84/113167.5, which
describes the aforesaid pyrido benzoxazlnes and their synthesis.
Examples of suitable spiro(indoline)pyrido benzo~azines include
those in which R1, R2, R3~ R4~ and R5 are the following
TABLE I
Compound R1 R2 R3 R4 R5
1 CH3 CH3 CH3 H H
2 CH3 CH3 CH3 CH3 CH3
3 CH3 CH3 CH3 OCH3 H
4 CH3 CH3 CH3 Cl CH3
CH3 CH3 C2H5 H H
6 CH3 CH3 C2H5 CH3 CH3
7 CH3 C2H5 C2H5 H H
8 n-C4H9 CH3 C2H5 H H
9 CH3 CH3 phenyl H H
CH3 phenyl phenyl 11 H
11 C2~5 CH3 C2H5 C113 C~13
12 n-C4Hg CH3 C2H5 CH3 CH3
Compound 2 in Table I may be named 1,3,3,4,5-(or 1,3,3,5,6-) pentamethyl-
spiro [indoline-2,3' [3H] pyrido [3,2-f] [1,4] benzoxazine]. Similarly,
compound 6 in Table I may be named 1,3,5,6-tetramethyl-3-ethylspiro
[indoline-2,3' [3H] pyrido [3,2-f] [1 9 4] benzoxazine]. Other compounds
in Table I can be similarly named taking into account the different sub-
stituents.
- 21 -
~L274~;~7
Spiro(indoline)naphthoxazines contemplated herein may be repre-
sented by the following graphic formula:
~4 2 R3
~ X1
Spiro(indoline)naphthoxazines and thelr synthesis are described in, for
example, U.S. Patents, 3,562,172, 3,578,602 and 4,215,010.
In graphic formula XI, Rl may b~ selected from hydrogen and
C1-C8 alkyl, e.g., methyl, R2 and R3 may each be selected
from hydrogen, C1-C5 alkyl, and phenyl, typically Cl-C2 alkyl
such as methyl and ethyl, R4 and R5 may each be selected from
hydrogen, C1-C5 alkyl, halogen, P.g., chlorine or bromine, nitro,
cyano, Cl-C5 alkoxy and C1-C5 alkoxycarbonyl, and R6 and
R7 may each be selected from hydrogen, halogen, e.g., chlorine and
bromine, and Cl-C4 alkoxy.
Specific examples of splro(indoline)naphthoxazines contemplated
herein, include those in which the substituents Rl-R7 are the
following:
~274at27
T~BLE II
Compound R1 R2 R3 R4 R5R6 R7
1 CH3 C~3 CH3 H H OC113 H
2 CH3 CH3 CH3 CH3 CH3 OCH3 H
3 CH3 CH3 CH3 OCH3 H OCH3 H
4 CH3 CH3 CH3 Cl CH3 OCH3 H
CH3 CH3 C2H5 H H OCH3 T1
6 CH3 CH3 C2H5 CH3 CH3 OCH3 H
7 CH3 C2H5 C2H5 H H OCH3 H
8 n-C4Hg CH3 C2H5 H H OCH3 H
9 CH3 CH3 phenyl H H OCH3 H
CH3 phenyl phenyl H H OCH3 H
11 CH3 P-C6H40CH3 p-C6H40CH3 H OCH3 U
12 C2H5 CH3 C2H5 CH3 CH3 OCH3 H
13 n-C4Hg CH3 C2H5 CH3 CH3 OCH3 H
Compound 2 in Table II may be named 1,3,3,5,6-pentamethyl-9'-methoxyspiro
[indolino 2,3' [3H]-naphtho [2,1-b] [1,4]-oxazine]. Similarly, compound
6 in Table II may be named 1,3,5,6-tetramethyl-3-ethyl-9'-methoxyspiro
[indolino-2,3' [3H]-naphtho [2,1-b] [1,4]-oxazine]. Other compounds in
Table II can be similarly named taking into account the different sub-
stituents.
Spiro~indoline)benzopyrans that are contemplated for use in the
present invention include those represented by the following graphic for-
mula:
- 23 -
1274~7
R4 R'2 R3
R'' ~ 6
Spiro(indoline~benzopyrans are known in the art. These benzopyrans and
their synthesis are described in U.S. Patents 3,100,778, 3,212,898 and
3,346,385 as well as in British Patent 1,418,089.
In graphic formula XII, R'1 may be hydrogen or a Cl-C4
alkyl, R'2 and R3 may each be hydrogen, Cl-C5 alkyl and
phenyl, e.g., Cl-C2 alkyl such as methyl and ethyl, R4 and R5
may each be hydrogen, halogen, e.g., chlorine or bromine, Cl-C4
alkyl, nitro, cyano, and Cl-C4 alkoxyl, and R6 and R'7 may
each be selected from hydrogen, Cl-C4 alkoxy, nitro, phenyl, and halo-
gen, e.g., chlorine or bromine.
Examples of spiro(indoline)benzopyrans include: 1,3,3-tri-
methyl-6'-nitro-spiro(2~1-1-benzopyran-2,2'-indoline); 1,3,3-trimethyl-6'-
nitro-8'-methoxy-spiro(2~1-1-benzopyran-2,2'-indoline); 1,3,3-trimethyl-
6'-nitro-8'-bromo-spiro(2H-l-benzopyran-2,2'-indoline); 1,3,3-trimethyl-
5'-bromo-6'-nitro-8'-methoxy-spiro(2H-1-benzopyran-2,2'-indoline); 1,3,3-
trimethyl-5-chloro-6'-nitro-spiro(2H-1-benzopyran-2,2'-indoline); and
l-phenyl-3,3-dimethyl-6'-nitro-spiro(2H-1-benzopyr2n-2,2'- indoline).
Spiro(indoline) naphthopyrans and spiro(indoline) qulnopyrans
may be represented by the following graphic formula XIII,
1~74a~7
R4 R2 R3 R6
~ ~ ~ (XIII)
wherein R1, R2, R3, R4 and R5 are as described with respect to
graphic formula X, R6 and R9 may each be selected from hydrogen,
Cl-C4 alkyl, C1-C4 alkoxy, nitro, and halogen, e.g~, chloro or
bromo, and Y is carbon or nitrogen respectively.
Examples of spiro(indoline)naphthopyrans, include: 1,3,3-tri-
methyl spiro[indoline-2,2'-[2H]-naphtho[1,2-b] pyran]; 1,3,3,5,6-penta-
methyl-spiro[indoline-2,2'-[2H]-naphtho[1,2-b[pyran]; 1,3,3-trimethyl-5-
methoxy-spiro[indoline-2,2'-[2H~-naphtho[1,2-b] pyran]; 1,3,3-trimethyl-
6'-chloro-spiro[indoline-2,2'-[2H]-naphtho[1,2-b]pyran]; and 1,3,3-tri-
methyl-6'-nitro-spiro[indoline-2,2' [2H]-naphtho[1,2-b] pyran].
Examples of spiro(indoline)quinopyrans include:
Spiro[2H-indole-2,3'-[3H]pyrano[3,2-f]quinoline; 1,3,3-trimethyl
Spiro[2H-indole-2,3'-[3Hlpyrano[3,2-f]quinoline; 1,3,3,5,6-pentamethyl
Spiro[2H-indole-~2,3'-[3H]pyrano[3,2-f]quinoline; 1,3,5,6-tetramethyl-
3-ethyl Spiro[2H-indole-2,3'-[3H]pyrano[3,2-f]quinoline; 1,3,3-trimethyl-
5-methoxy Spiro[2H-indole-2,3'-[3H]pyrano[3,2-f]quinoline; and
5-chloro-1,3,3,6'-tetramethyl Sprio[2H-indole-2,3'-[3H]pyrano]3,2-f]-
quinoline.
- 25 -
~7~4;~7
Spiro(indoline)-benzoxazines, -pyridopyrans, and -pyridoox-
azines may be represented by the following graphic formula XIV,
~ ~ ~ R6 (XI~)
R5
Rg
wherein Rl, R2, R3~ R4, and R5 are as described w~th respect to
graphic formula XIV, Z and Y are nitrogen and carbon, carbon and
nitrogen, and nltrogen and nitrogen respectively, and R6 and Rg are
as described with respect to graphic formula XIII.
In accordance with the present invention, a polymerizate of an
organic plastic host material, such as a polymerizate of diethylene gly-
col bis(allyl carbonate), copolymers of diethylene glycol bis(allyl car-
bonate) and from 10-20 percent vinyl acetate, or polycarbonate, are
degreased with an organic solvent such as methylethylketone to provide a
clean surface. Static charges are eliminated from the cleaned surface by
passing a high voltage discharge brush over the cleaned surface. A solu-
tion of a spiro(indoline)-type photochromic substance, such as a spiro-
(indoline)pyrido benzoxazine, and a polyvinylchloride resin in a readily
volatile organic solvent is then applied to the cleaned and substantially
static-free surface(s) of the plastic host, e.g., by spraying the solu-
tion onto the surface(s) thereby, to form a very thin, e.g., about 0.5 to
- 26 -
~;274~7
3 mils thick substantially dry coating or film of the polymeric resin
containing from about 30 to 35 percent of the photochromic substance.
The surface coated plastic host ls then treated in a heating zone at tem-
peratures below the melting temperature of the photochromic substance for
between about 10 and 60 minutes to thereby transfer the photochromic sub-
stance from the polymeric resin coating into the subsurface region of the
plastic host. After cooling, the photochromic-lean polymeric resin film
i8 removed by contacting the film with an organic solvent, such as methyl-
ethylketone. The photochromic-treated plastic host is optionally tinted
with a conventional dye which complements the color of the photochromic
substance. Thereafter the surface is washed with soapy water to remove
residues of dye and organic solvent and the article dried. The photo-
chromic (and optionally tinted) treated plastic can then be formed into
shapes such as lenses by known forming, e.g., thermoforming, techniques.
Thermoforming is a process wherein a flat lens is transformed
into a concave shape by thermal treatment of the lens, e.g., a flat lens
is placed on a female die, the geometry of which corresponds to a small
circular segment of a sphere of a radius of, for instance, 9 centimeters
and the lens is heated and pressed against said female die for several
minutes.
The present process is more particularly described in the fol-
lowing examples which are intended as illustrative only since numerous
modifications and variations therein will be apparent to those skilled in
the art.
Example
An air sprayable photochromic compound-containing solution was
prepared by dissolving one part of the photochromic compound in 17 parts
1~74~7
of methyl ethyl ketone and 17 parts of toluene. Two parts of a polyvinyl
chloride resin (Strip Coat 2253 available from the 3M Company) were dis-
solved in 9 parts of about an 80/20 toluene-methyl isobutyl ketor.e mix-
ture. The two resulting solutions were mixed and sprayed with a conven-
tional air atomization spray gun on a 1 inch (2.54 cm) x 2 inch (5.08 cm)
x 0.125 inch (0.32 cm) solid plastic coupon prepared from diethylene gly-
col bis(allyl carbonate). The solution was applied to the coupon using 4
successive coverages. All surface areas of the coupon received multiple
coverages to achieve maximum film uniformity. The resulting film was
substantially dry the instant it was applied to the coupon. The film was
permitted to dry completely and the coated coupons heated in an air circu-
lating oven for 20 minutes at 160C. When cooled, the photochromic spent
film was removed with either acetone or methyl ethyl ketone.
The coupons with the photochromic compound imbibed therein were
irradiated with a Xenon high pressure arc lamp at an ultraviolet energy
level of 3.0 milliwatts per square centimeter. The lamp was fitted with
an OX-l filter. The change in optical density (QOD) was measured with a
radiometer at 30 seconds illumination and at 4 minutes (saturation).
Ultraviolet absorbance at 347 nanometers (~max) was also measured with a
spectrophotometer.
These data are reported in Table III.
TABLE III
PHOTOCHROMIC MATERIA_ Ultraviolet ~OD
Absorbence,
Table Compd. No. at ~Max 30 sec.Saturation
I 1 2.60 0.46 0.73
I* 2 1.35 0.77 1.43
I 3 1.72 0.71 1.37
- 28 -
12~44~7
I 6 1.18 0.79 1.52
I 11 0.85 0.47 0.86
I 12 0.79 0.57 0.96
II 2 1.63 0.36 0.70
II 3 1.80 0.36 0.71
II 6 1.76 0.43 0.91
II 7 1.94 0.29 0.63
II 9 1.88 0.32 0.64
II 11 0.60 0.13 0.38
II 12 0.87 0.35 0.65
II 13 1.20 0.36 0.72
* 2.5 parts of polyvinyl chloride resin used.
The data of Table III show that the described method is effec-
tive for incorporating photochromic compounds into a synthetic plastic
host material.
While the above invention has been illustrated partlcularly
with spiro(indoline) pyrido benzoxazine and spiro(indoline) naphthoxazine
photochromic materials and the polymerizate of diethylene glycol bis-
(allyl carbonate) as the plastic host, it is expected that substantially
similar results will be obtained by substituting other photochromic mate-
rials described herein for the aforesaid spiro(indoline)-type photo-
chromic materials and other plastic host materials described herein for
the polymerizate of diethylene glycol bis(allyl carbonate).
Although the present invention has been described with refer-
ence to specific details of certain embodiments thereof, it is not intended
~ 29 -
~J
that such details should be regarded as limitations upon the scope of
the invention except as and to the extent that they are included in the
accompanying c1aims.
- 30 -
