Technical Field
The present invention relates to a primer composition
having photochromic property and impact resistance for
coating transparent materials and to a photochromic
transparent material having a primer layer formed by coating
and curing the primer composition.
Background Art
The primer composition for coating transparent
materials according to the present invention is applied to
various transparent materials requiring transparency such as
lenses for glasses, glass for cars, optical lenses, optical
films, etc. Raw materials for transparent materials include
plastics and glass. Among these, plastic lenses have strong
breaking resistance and a lighter weight compared to glass
and thus are largely used as substitutes for transparent
glass. Particularly, plastic lenses are widely used in the
field of optical lenses or lenses for glasses.
Materials for transparent plastic lenses include
polyallylcarbonate, acrylic resin or polythiourethane. Such
materials for transparent plastic lenses have soft surfaces
and tend to be cracked or scratched. Therefore, such
materials have a need of surface reinforcement, for example,
by a silicone-based hard coating. However, a silicone-based
hard coating is problematic in that it decreases impact
resistance of a plastic lens. Accordingly, in order to
prevent such a problem, it is necessary to coat a primer

layer between a plastic lens and a hard coating layer.
Japanese Laid-Open Publication No. H8-54501 discloses a
method for improving impact resistance of a plastic lens,
wherein a layer formed of urethane-based resin is used as a
primer layer.
Meanwhile, use of a photochromic compound as a primer
layer has been disclosed in the prior art. For example,
Japanese Laid-Open Publication No. H3-269507 discloses a
photochromic lens comprising a plastic substrate, a hard
coating layer formed of silicone resin and a primer layer
between the plastic substrate and the hard coating layer, the
primer layer containing a photochromic substance. In
addition, use of photochromic coating composition is
disclosed in several patent publications including Japanese
Laid-Open Publication No. H5-28753 and US Patent' Nos.
4,889,413, 6,107,396, 6,187,444, 6,268,055, 6,060,001 and
6,436,525.
However, when a photochromic dye combined with
polyurethane is coated on a plastic substrate as a primer
coating layer, there are problems in that the optical density
is low and the bleaching rate is also low. Additionally, when
the thickness of a primer layer is increased to 10 pm or more
so as to obtain a high optical density, the hardness of a
hard coating layer is decreased after applying the hard
coating layer.
Generally, important factors to evaluate a photochromic
lens are a high activation/bleaching rate, a high optical
density (OD) and fatigue resistance. Among these factors,
fatigue resistance can be improved by the selection of a
suitable matrix and the addition of a UV stabilizer, etc.

Therefore, it is necessary to increase the optical density of
a lens while maintaining a desired activation/bleaching rate.
Particularly, it is an imminent subject in the field of
photochromic primer coatings to improve the optical density.
The most important factors determining the optical density of
an organic photochromic dye are a structure of the dye itself
and environments of the dye. However, these factors have not
been considered heretofore in photochromic primer
compositions according to the prior art.
Disclosure of the Invention
The present inventors have found that when a
photochromic dye is used to apply a photochromic primer
coating layer on a transparent plastic material, a high
optical density can be obtained even at a small coating layer
thickness if the environment of the dye is polar. Because the
polarity of environments of the dye increases, the activated
dye molecules are more stabilized. Additionally, they have
found that as a free volume present in constitutional
elements of a primer composition increases, reversible,
activation/bleaching of a photochromic dye is facilitated and
thus the activation/bleaching rate increases.
Therefore, the present invention has been made based on
these findings. It is an object of the present invention to
provide a primer composition for coating transparent
materials and a transparent material having a primer layer
formed by coating and curing the primer composition, wherein
the primer composition comprises a polyurethane containing a
Brϴnsted salt, a polyepoxy resin and a photochromic dye.
According to an aspect of the present invention, there

is provided a primer composition for coating transparent
materials, comprising: (a) 5-90 parts by weight of a
polyurethane containing a Bransted salt; (b) 5-50 parts by
weight of a polyepoxy resin; and (c) 1-40 parts by weight of
a photochromic dye, based on 100 parts by weight of the total
primer composition.
According to another aspect of the present invention,
there is provided a photochromic transparent material having
a primer layer formed by coating and curing the above-
described primer composition on the surface of the
transparent material.
The foregoing and other objects, features and
advantages of the present invention will be explained in
detail hereinafter.
In the primer . composition according to the present
invention, the first component, i.e., the. polyurethane is
characterized by containing a Brϴnsted salt and thus having
polarity. The Bransted salt provides the photochromic dye
contained in the primer layer formed by the primer
composition with polar environment.
Such effect may be explained as follows: most
photochromic dyes such as merocyanine may be transformed into
an activated state having a zwitterion by a cleavage of a
certain chemical bond in the original structure of the dye,
when exposed to UV, etc. By virtue of the polyurethane
containing a Brϴnsted salt, the activated photochromic dye
can be provided with polar environment. When UV is
irradiated, such polar environment can stabilize the
activated dye and can minimize the progress of a reverse
reaction so that a strongly activated state can be

maintained. Therefore, even if the photochromic primer
coating layer has a small thickness, a high optical density
can be accomplished.
According to the present invention, the Brϴnsted salt
in the polyurethane may be provided by a reaction product
between an aminodiol and a Brϴnsted acid. Such a Bronsted
salt formed of an anionic conjugate base of a Bransted acid
and a cationic amine stabilizes an activated photochromic dye
having zwitterions so that a high optical density can be
obtained.
Other physical properties of polyurethane are
determined by characteristics of a polyol and an isocyanate
used in the preparation of the polyurethane. Particularly,
physical properties of polyurethane may be determined . by
controlling the ratio of a hard segment to a soft segment in
the polyurethane through the kind and amount of the polyol.
The soft segment of polyurethane is produced by the reaction
of an isocyanate and a high molecular weight polyol such as a
polyester polyol or polyether polyol. The soft segment
provides the photochromic dye with a free space required to
perform a reversible reaction and provides. a transparent
material to which the primer composition according to the
present invention is applied with impact resistance. The hard
segment of polyurethane is produced by the reaction between
an isocyanate with a low molecular weight polyol. The hard
segment improves mechanical strength, heat resistance and
chemical resistance of a coating layer formed by the primer
composition according to the present invention.
Examples of the polyurethane containing a Brϴnsted salt
that may be used in the present invention include Estane

5778, Estane 5707, Estane 5701, etc., available from Noveon,
Inc. Among these, the polyurethane, Estane 5778 is a
thermosetting polyurethane resin containing an aromatic
polyester functional group. Estane 5778 can disperse metal
oxides, pigments, etc., stably and has a high solubility to a
solvent such as methylethyl ketone, dimethylformamide,
tetrahydrofuran, cyclohexanone, or the like. It is largely
used in the manufacture of recording media such as
videotapes, audiotapes, etc.
Since the polyurethane containing a Bransted salt is a
reaction product of an isocyanate with a polyol, the primer
composition of the ' present invention may include a
polyurethane reaction mixture (reaction mixture for preparing
polyurethane) comprising an isocyanate and a polyol, instead
of the polyurethane.
The isocyanate component used in the preparation of the
polyurethane containing a Brϴnsted salt is preferably an
aliphatic isocyanate, an alicyclic isocyanate, an aromatic
isocyanate, a heterocyclic isocyanate, a blocked aliphatic
isocyanate or a blocked alicyclic isocyanate. More
particularly, preferred examples of the isocyanate component
include diisocyanates such as hexamethylene diisocyanate,
1,3,3-trimethyl hexamethylene diisocyanate, isophorone
diisocyanate, toluene-2,6-diisocyanate, 4,4'-
dicyclohexylmethane diisocyanate, etc.
Preferably, the polyol used in the preparation of the
polyurethane containing a Bransted salt includes: (i) a diol
containing a Bransted salt, (ii) a polyol generating a soft
segment of polyurethane, and (iii) a polyol generating a hard
segment of polyurethane.

The diol (i) containing a Brϴnsted salt may be a
reaction product of an aminodiol with a Bransted acid. The
aminodiol may be prepared by conventional methods well known
to persons skilled in the art. Particular examples of the
aminodiol include 2-amino-2-methyl-l,3-propanediol, N-(n-
butyl) diethanolamine, 3-diethylamino-l, 2-propanediol, N- (t-
butyl)diethanolamine, N-methyldiethanolamine, N-
phenyldiethanolamine, diethyl N,N-bis(2-
hydroxyethyl) aminomethyl phosphonate, etc.
The Brϴnsted acid to be reacted with the aminodiol may
include phosphonic acid, phosphinic acid or sulfonic acid.
Preferred examples of the Bransted acid include
methylphosphonic acid, ethylphosphonic acid, propylphosphonic
acid, butylphosphonic acid, t-butylphosphonic acid,
methylenediphosphonic acid, 2-chloroethylphosphonic ' acid,
phenylphosphonic acid, phosphonoacetic acid,
phosphonopropionic acid, methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, sulfoacetic acid, sulfosuccinic
acid, benzenesulfonic acid, ethylbenzenesulfonic acid, 4-
hydroxybenzenesulfonic acid, etc., but are not limited
thereto.
Non-limitative examples of the polyol (ii) generating a
soft segment of polyurethane include a polyesterdiol,
polyetherdiol, polyacrylic diol and polycarbonate diol. When
the polyol (ii) has a molecular weight less than 300 g/mole,
impact resistance and optical density may be decreased. On
the other hand, when the polyol (ii) has a molecular weight
exceeding 6,000 g/mole, coatability may be deteriorated.
Therefore, the polyol (ii) preferably has a molecular weight
of 300 to 6,000 g/mole and more preferably 500 to 2,000

g/mole. Further, the amount of the polyol (ii) is preferably
10-70 parts by weight and more preferably 20-60 parts by
weight, based on 100 parts by weight of the polyurethane.
Preferably, the polyol (iii) generating a hard segment
of polyurethane is a low molecular weight polyol having a
molecular weight of 50 to 500 g/mole. Examples of the polyol
(iii) may include 1,4-butanediol, l,2~butanediolr 1,5-
pentanediol, 2,4-pentanediol, 1,4-cyclohexanediol, 1,6-
hexanediol, 2,5-hexanediol, 2,4-heptanediol, pentaerythritol
and trimethylolpropane, but are not limited thereto. Further,
the amount of the polyol (iii) is preferably 1-50 parts by
weight and more preferably 5-30 parts by weight, based on 100
parts by weight of the polyurethane.
According to the present invention, a catalyst may be
used for preparing the polyurethane containing a Bransted
salt. Such catalysts include a Lewis base, a Lewis acid.or an
insertion reaction catalyst well known to persons skilled in
the art, etc. Particular examples of the catalyst may include
tin octylate, dibutyltin diacetate, dibutyltin dilaurate,
dibutyltin mercaptide, dibutyltin dimaleate, dimethyltin
hydroxide, triethylamine, etc., but are not limited thereto.
Preferably, the Bransted salt in the polyurethane
exists in the ratio of 10 to 100 gram equivalents per IXio6 g
of polyurethane. Although the Brϴnsted salt exists in such a
small amount, it provides polar environment to a photochromic
dye so that optical density can be improved.
In the polyurethane containing a Bransted salt,
isocyanate and polyol are present in such an amount that the
mole ratio between both functional groups of NCO and OH,
i.e., NCO/OH ranges preferably from 0.5 to 3.0 and more

preferably from 0.75 to 2.0. If the mole ratio is less than
0.5, the coating layer formed by the primer coating
composition cannot be cured sufficiently. On the other hand,
if the mole ratio between both functional groups is more than
3.0, unreacted isocyanate may exist and thus have possibility
to react with an upper hard coating layer, thereby detracting
from the performance and appearance of the hard coating
layer.
The amount of the polyurethane reaction mixture
containing an isocyanate with a polyol or the polyurethane is
preferably 5 to 90 parts by weight based on 100 parts by
weight of the total primer composition. If the amount is less
than 5 parts by weight, impact resistance and optical density
may be decreased, while the amount is more than 90 parts by
weight, activation/bleaching rate becomes low and adhesive
property may be decreased.
According to the primer composition of the present
invention, it is preferable that the second component, i.e.,
the polyepoxy resin is linear and has a molecular weight of
about 300-2,000 g/mole. Epoxy groups in the epoxy resin can
react with hydroxy groups present in the polyurethane
reaction mixture or polyurethane. This results in ring-
opening of epoxy groups simultaneously with the generation of
new OH groups, which in turn can react with NCO groups
present in the isocyanate to form urethane bonds that may
become a part of the polyurethane. Additionally, unreacted
epoxy groups may react with OH groups present in an upper
hard coating layer so that the primer layer can be in close
contact with the hard coating layer. Further, use of the
polyepoxy component result in the formation of an additional

free space in the primer layer formed by the primer
composition according to the present invention. Therefore,
the chemical structural change of a photochromic dye may be
facilitated and thus activation/bleaching rate may be
increased.
Preferably, the amount of the polyepoxy resin is 5 to
50 parts by weight based on 100 parts by weight of the total
primer composition. If the amount is less than 5 parts by
weight, adhesive property becomes poor, while if the amount
is more than 50 parts by weight, coatability may be
decreased.
Examples of the polyepoxy resin that may be used in the
present invention include bisphenol A epoxy of Lucky Epoxy
Resin, available from LG Chem., Ltd., polysulfido-modified
epoxy resin Flep available from Toray Thiokol Corp., or the .
like. For example, polyepoxy resin LER-840, which is a
typical example for the bisphenol A epoxy of Lucky Epoxy '
Resin, is a polyepoxy resin having two epoxy groups at both-
ends and comprising bisphenol A as a basic structure. It has
an epoxy equivalent of 180-190 and a viscosity of 9000-11000
cps at 25°C. It also has excellent adhesive properties, low
shrinkage, high chemical resistance and other advantages. .
Further, because it has a relatively long chain and a large
molecular weight, it can form an additional free space in the
structure of a primer layer. Therefore, it causes a
photochromic dye to be easily changed in chemical. structure,
thereby increasing activation/bleaching rate and optical
density.
According to the present composition, the third
component for providing photochromic property may be any

photochromic dyes with no particular limitation. For example,
benzopyran-, naphthopyran-, phenanthropyran-,
indenonaphthopyran-, fulgide, spirooxazine-, and spiropyran-
based compounds may be used. One primer composition according
to the present invention may include various photochromic
dyes so as to exhibit various colors.
The amount of the photochromic dye is preferably 1 to
40 parts by weight based on 100 parts by weight of the total
primer composition. If the amount is less than 1 part by
weight, optical density is low, while if the amount is more
than 40 parts by weight, coatability is poor.
The primer composition according to the present
invention may dissolve in an organic solvent to apply on a
transparent material. Organic solvents that may be used in
the present invention include alcohols, ketones, esters and
ethers. More particularly, methylethyl ketone, acetylacetone,
ethylcellosolve acetate, diacetone alcohol, ethyl acetate,
etc., are preferably used.
The primer composition according to the present
invention may be coated on a transparent material,
particularly on a plastic lens, etc. More particularly, the
primer composition according to the present invention may be
applied to materials including polycarbonates, acrylic
resins, polydiethylene glycolbisallyl carbonate(CR-39) and
polyethylene terephthalate. The primer composition according
to the present invention has excellent adhesion force to the
above-described materials and photochromic property with
which it is activated in the outdoor environment and is
bleached in the indoor environment. In order to provide a

lens with a higher optical density and improved fatigue
resistance when the lens is exposed to UV light, it is
important to select a suitable matrix. Also, various
additives (for example, a UV stabilizer such as Tinuvin available from Ciba-Geigy Japan Corp., a surfactant, etc.)
may be added to the matrix.
Preferably, the primer composition according to the
present invention is coated on a plastic lens by a suitable
method including a dipping method, a spin coating method, etc., and then is cured at 50-150°C for 0.5-4 hours. In order
to prevent the deterioration and deformation of the plastic
material due to overheating during a curing process, it is
more preferable that the primer composition is cured at 90-
120°C for 0.5-4 hours.
According to the present invention, dry coating
thickness may be 0.1-40 pm, preferably 1-10 urn and more
preferably 2-5 urn. If the thickness is less than 2 um,
optical density is low. On the other hand, if the thickness
is more than 5 um, hardness may be decreased after applying a
hard coating layer.
Since the plastic lens coated with the photochromic
primer layer has a soft surface, it is preferable to apply a
hard coating layer on the grimer layer. Even if a hard
coating layer is formed, the primer coating layer formed
between the hard coating layer and the plastic lens can
prevent decrease of impact resistance.
Silicone resins are preferable for a hard coating agent
used for forming the hard coating layer. Preferred examples
of silicone resins include compositions based on (A)
inorganic oxide sol formed of nano-particles having a

particle diameter of 1-100 nra including at least one element
selected from the group consisting of Ti, Zr, Si, M, Sn, Sb,
Ta, Ce, La, Fe, Zn, W and In; (B) a silane compound having no
functional group; and/or (c) an epoxy-containing silicone
compound or hydrolyzate thereof.
The inorganic oxide sol (A) improves the hardness, heat
resistance and weather resistance of a hard coating layer and
increases the refractive index of a hard coating layer
approximately to that of the lens so that a light
interference phenomenon can be prevented. The protective
coating agent including the silane compound (B) having no
functional group may be a commercially available hard coating
composition and is preferably STUMS available from LG Chem.,
Ltd. Examples of the epoxy-containing silicone compound (C)
include yglycidoxypropyl trimethoxysilane, yglycidoxypropyl
methyldiethoxysilane, Y~glycidoxyProPyl triethoxy-silane,
etc.
Methods for coating a hard coating composition on the
primer coating layer include a dipping method, a flow method,
a spin coating method, a spray coating method, etc., but are
not limited thereto.
The hard coating layer can be formed by applying a hard
coating composition onto the primer layer on the surface of a
plastic lens, heating it at 80-120°C for 1-24 hours and then
curing it. The thickness of a hard coating layer is
preferably 0.5 to 5 um and more preferably 1-4 um.
Best Mode for Carrying Out the Invention
Reference will now be made in detail to the preferred
embodiments of the present invention, however the scope of

the present invention is not restricted by the embodiments.
Example 1
Preparation of Primer Composition for Coating
Transparent Materials
296 g of methylethyl ketone, 351 g of ethylcellosolve
acetate and 164 g of acetylacetone were added to a jacketed
reactor. 72 g of polyurethane, Estane 5778 available from
Noveon Inc. (polyurethane containing a Brϴnsted salt) was
added thereto and the mixture was stirred for about 1 hour.
To the stirred mixture, 26.7 g of polyepoxy resin, LER-840
available from LG Chem., Ltd., was added and the resultant
mixture was stirred until it is homogenized. Then, added were
12 g of a photochromic dye (naphthooxazine exhibiting a blue
color when exposed to UV) and 1.4 g of Tinuvin 144 available
from Ciba-Geigy Corp. as a UV stabilizer- Further, TEGO-410
and TEGO-450 available from TEGO Inc. were added as leveling
agents, each in the amount of 1.57 g.
Lens Coating Using Primer Composition
A medium-refractive index lens for glasses (BS
available from H7AND0K Optec Co., Ltd.; refractive index
1.553) was etched in NaOH at 60°C for 4 minutes, dipped in the
coating composition obtained as described above to be coated
with the coating composition and dried at 110 °C for 60
minutes.
The coated lens was further dip-coated with a silicone-
based hard coating protective layer, STUMS available from LG
Chem., Ltd. and cured at 120°C for 2 hours.
Example 2
308 g of methylethyl ketone, 366 g of ethylcellosolve
acetate, 171 g of acetylacetone and 54.6 g of polyurethane,

Estane 5778 available from Noveon Inc. were added to a
jacketed reactor at room temperature and the mixture was
stirred for about 1 hour. To the stirred mixture, 48.4 g of
polyepoxy resin, LER-840 available from LG Chem., Ltd. was
added and the resultant mixture was stirred for about 30
minutes. Then, added were 12 g of a photochromic dye
(naphthooxazine exhibiting a blue color when exposed to UV)
and 1.4 g of Tinuvin 144 available from Ciba-Geigy Corp. as a
UV stabilizer. After stirring for about 30 minutes, TEGO-410
and TEGO-450 available from TEGO Inc. were added as leveling
agents, each in the amount of 1.57 g.
Next,' a medium-refractive index lens for glasses was
coated with the primer composition and further coated with a
hard coating protective layer, according to the same method
as Example 1.
Comparative Example 1
331 g of methylethyl ketone, 393 g of ethylcellosolve
acetate, 183 g of acetylacetone and 80.5 g of polyurethane,
Estane 5778 available from Noveon Inc. were added to a
jacketed reactor at room temperature and the mixture was
stirred for about 1 hour. To the stirred mixture, 9.2 g of a
photochromic dye (naphthooxazine exhibiting a blue color when
exposed to UV) and 1.1 g of a UV stabilizer were added. After
stirring for about 30 minutes, TEGO-410 and TEGO-450
available from TEGO Inc. were added as leveling agents, each
in the amount of 1.57 g.
Next, a medium-refractive index lens for glasses was
coated with the primer composition and further coated with a
hard coating protective layer, according to the same method
as Example 1.

Comparative Example 2
327 g of methylethyl ketone, 389 g of ethylcellosolve acetate,
181 g of acetylacetone and 110 g of polyepoxy resin, LER-840
available from LG Chem., Ltd. were added to a jacketed
reactor at room temperature and the mixture was stirred for
about 1 hour. To the stirred mixture, 12.4 g of a
photochromic dye (naphthooxazine exhibiting a blue color when
exposed to UV) and 1.4 g of a UV stabilizer were added. After
stirring for about 30 minutes, TEGO-410 and TEGO-450
available from TEGO Inc. were added as leveling agents, each
in the amount of 1.57 g.
Next, a medium-refractive index lens for glasses was
coated with the primer composition and further coated with a
hard coating protective layer, according to the same method
as Example 1.
Comparative Example 3
Example 1 was repeated to provide a primer composition
and a photochromic lens, except that D-ACE-606NY,
polyurethane available from DONGSUNG Chemical Co., Ltd. was
used instead of Estane 5778, polyurethane available from
Noveon Inc.
The polyurethane, D-ACE-606NY available from DONGSUNG
Chemical Co., Ltd. is a polyurethane resin having polyester
functional groups. It is a one-part resin of non-yellowing
type containing no Brϴnsted salt in its structure and having
excellent liquid stability and weather resistance. It is
largely used in clothes and direct coating technologies.
Comparative Example 4
50.53 g of methylethyl ketone, 50.53 g of toluene,
50.53 g of ethyl acetate, 3.27 g of linear polymeric

polytetrahydrofuran having a molecular weight of 1,000, 3.25
g of 1,4-butanediol, 3.25 g of trimethoxypropane and 3.25 g
of polyester, DESMOPHEN 67 0A 80 available from Bayer Co. (a
saturated polyester resin dissolved in n-butyl acetate) were
added to a jacketed reactor at room temperature and the
mixture were stirred for about 1 hour. To the stirred
mixture, 4 g of a photochromic dye (naphthooxazine exhibiting
a blue color when exposed to UV) , 1.4 g of a UV stabilizer,
85 g of VESTANAT B 1358A available from Degussa Corp. (a
blocked alicyclic polyisocyanate) and 0.64 g of dibutyltin
dilaurate were added. After stirring for about 30 minutes,
TEGO-410 and TEGO-450 available from TEGO Inc. were added as
leveling agents, each in the amount of 0.4 6 g.
Next, a medium-refractive index lens for glasses, was
coated with the primer composition and further coated with a
hard coating protective layer, according to the same method
as Example 1.
Experimental Example
The following experiments were performed for each lens
obtained by Examples 1 and 2 and Comparative Examples 1-4.
The results are shown in the following Table 1.
(1) Optical density (AOD)
Cured lenses were irradiated with UV light having a
wavelength of 365nm (1.35 mW/cm2) for 2 minutes. Right after
this, the output light was measured for each lens at an
activated state and a bleached state by using a UV-Vis
detector. The optical density (AOD) at an activated state
based on the optical density at a bleached state was
calculated by the following formula:


(2) Scratch resistance: Scratch test with #0000 steel
wool
Steel wool was mounted on the front-end of a cylinder
having a diameter of 25 ram and contacted with the surface of
a sample. They were rotated five times under a load of 100 g
and then observed by the naked eye. (0: no damage on the
surface, A: slightly damaged, X: excessively damaged).
(3) Adhesive property
A crosscut cellotape peel test was performed for each
coating in a crosslinked and cured state. More particularly,
each coating was notched with 11x11 lines in the longitudinal
direction and the horizontal direction by a crosscut method
at the line interval of 1 mm to form 100 divisions each
having an area of 1 mm2. A cellotape was adhered on the
notched coating and. removed rapidly. Such operation was
repeated three times at one position.
Or no peeling after repeating 3 times
A: peeling at 1 to 50 divisions after repeating 3
times
X: peeling at 51-100 divisions after 3 times
(4) Impact resistance
Steel balls having a weight of 16.32 g and 24.82 g were
set at a height of 131 cm and 154 cm, respectively, and
dropped downwardly to impact on the convex surface of a lens.
Such a breaking test was repeated while the impact energy was
gradually increased. When a lens was broken or cracked, the
impact energy value at the preceding energy level was
designated as impact resistance in terms of impact energy

(J) . According to the FDA standards, such impact energy
should be 0.2 J or more.
(5) Coating layer thickness
The section of a coated lens was observed with a FE-SEM
(field emission scanning electron microscope) to determine a
coating layer thickness.

As shown in Table 1, Examples 1 and 2 show excellent
optical density values compared to Comparative Examples 1-4.
Additionally, each primer coating layer formed by the primer

coating compositions according to Examples 1 and 2 has ti/2
(half-time of bleaching' rate) of 90 seconds or less and thus
is acceptable as a primer coating.
Industrial Applicability
As mentioned above, conventional photochromic primer
coatings formed on plastic materials by using a photochromic
dye have disadvantages in that they have a low optical
density and a low bleaching rate. However, as can be seen
from the foregoing, the primer composition according to the
present invention comprising a polar polyurethane containing
a Brϴnsted salt, a polyepoxy resin and a photochromic dye
shows a high optical density and a high activation/bleaching
rate when coated on a plastic lens.
It is to be understood that the "primer composition"
and the "protochromatic transparent material" having a layer
of such "primer composition" are not useful for, or relate
to the production/control/use or disposal of Atomic Energy,
nor any radioactive substance is used in Atomic Energy
operations.

WE CLAIM:
1. A primer composition for coating transparent
materials, comprising:
a) 5-90 parts by weight of a polyurethane containing a
Bransted salt;
b) 5-50 parts by weight of a polyepoxy resin; and
c) 1-40 parts by weight of a photochromic dye, based on
100 parts by weight of the total primer composition.

2. The primer composition for coating transparent
materials as claimed in claim 1, wherein the Brϴnsted salt
is present in the polyurethane containing a Brϴnsted salt in
an amount of 10-100 gram equivalents per 1x106 g of the
polyurethane.
3. The primer composition for coating transparent
materials as claimed in claim 1, wherein the polyurethane
containing a Brϴnsted salt is a reaction product of an
isocyanate with a polyol, the isocyanate and polyol being
present in such an amount that the mole ratio between both
functional groups of NCO and OH (NCO/OH) ranges from 0.5 to
3.0.
4. The primer composition for coating transparent
materials as claimed in claim 1, wherein the polyurethane
containing a Brϴnsted salt is a reaction product of an
isocyanate with a polyol, the isocyanate being selected from
the group consisting of an aliphatic isocyanate, an
alicyclic isocyanate, an aromatic isocyanate, a heterocyclic
isocyanate, a blocked aliphatic isocyanate and a blocked
alicyclic isocyanate.
5. The primer composition for coating transparent
materials as claimed in claim 1, wherein the polyurethane
containing a Brϴnsted salt is a reaction product of an
isocyanate with a polyol, the polyol including: (i) a diol
containing a Brϴnsted salt, (ii) a polyol generating a soft

segment of polyurethane, and (iii)a polyol generating a hard
segment of polyurethane.
6. The primer composition for coating transparent
materials as claimed in claim 5, wherein the diol containing
a Brϴnsted salt is a reaction product of an aminodiol with a
Brϴnsted acid.
7. The primer composition for coating transparent
materials as claimed in claim 6, wherein the aminodiol is
selected from the group consisting of 2-amino-2-methyl-l, 3-
propanediol, N-(n-butyl)diethanolamine, 3-diethyl-amino-l,2-
propanediol, N-(t-butyl)diethanolamine, N-
methyldiethanolamine, N-phenyldiethanolamine and diethyl
N,N-bis(2-hydroxyethyl)aminomethyl phosphonate.
8. The primer composition for coating transparent
materials as claimed in claim 6, wherein the Brϴnsted acid
is selected from the group consisting, of phosphonic acid,
phosphinic acid and sulfonic acid.
9. The primer composition for coating transparent
materials as claimed in claim 5, wherein the polyol
generating a soft segment of polyurethane is selected from
the group consisting of a polyester diol, a polyether diol,
a polyacrylic diol and a polycarbonate diol.

10. The primer composition for coating transparent
materials as claimed in claim 5, wherein the polyol
generating a hard segment of polyurethane is selected from
the group consisting of 1,4-butanediol, 1,2-butanediol, 1,5-
pentanediol, 2,4-pentanediol, 1,4-cyclohexanediol, 1,6-
hexanediol, 2,5-hexanediol, 2,4-heptanediol, pentaerythritol
and trimethylolpropane.
11. The primer composition for coating transparent
materials as claimed in claim 1, wherein the polyurethane

containing a Brϴnsted salt is a polyurethane reaction
mixture containing an isocyanate and a polyol.
12. The primer composition for coating transparent
materials as claimed in claim 1, wherein the polyepoxy resin
is linear and has a molecular weight of 300-2,000 g/mole.
13. The primer composition for coating transparent
materials as claimed in claim 1, wherein the photochromic
dye is selected- from the group consisting of benzopyran-,
naphthopyran-, phenanthropyran-, indenonaphthopyran-,
fulgide, spirooxazine-, and spiropyran-based compounds.

14. A photochromic transparent material having a primer
layer formed by coating and curing the primer composition as
claimed in any one of claims 1 to 13 on a surface of a
transparent material.
15. The photochromic transparent material as claimed in
to claim 14, wherein the primer layer has a .thickness of 0.1
um to 4 0 um.
16. The photochromic transparent material as claimed in
claim 14, wherein a hard coating layer is formed on the
primer layer.
17. The photochromic transparent material as claimed in
claim. 16, wherein the hard coating layer comprises at least
one component selected from the group consisting of at least
one inorganic oxide sol containing at least one element
selected from the group consisting of Ti, Zr, Si, Al, Sn,
Sb, Ta, Ce, La, Fe, Zn, W and In; a silane compound having
no functional group; and an epoxy-containing silicone
compound or hydrolyzate thereof.

ABSTRACT

PHOTOCHROMIC PRIMER COMPOSITION HAVING HIGH IMPACT RESISTANCE AND
TRANSPARENT MATERIAL COATED WITH THE SAME
The present invention discloses a primer composition having photochromic property and impact
resistance for coating transparent materials and a photochromic transparent material having a primer
layer formed by coating and curing the primer composition. The primer composition for coating
transparent materials comprises:
a) 5-90 parts by weight of a polyurethane containing a Bronsted salt;
b) 5-50 parts by weight of a polyepoxy resin; and
c) 1-40 parts by weight of a photochromic dye, based on 100 parts by weight of the total
primer composition. The photochromic transparent material having a primer layer formed by coating
and curing the primer composition shows excellent photochromic property and impact resistance.