U.S. patent application number 12/541089 was filed with the patent office on 2011-02-17 for photochromic optical article.
This patent application is currently assigned to DARWIN OPTICAL CO., LTD.. Invention is credited to Yi-Tang Wang, Yun-Cheng Wang.
Application Number | 20110038024 12/541089 |
Document ID | / |
Family ID | 43531971 |
Filed Date | 2011-02-17 |
United States Patent
Application |
20110038024 |
Kind Code |
A1 |
Wang; Yun-Cheng ; et
al. |
February 17, 2011 |
PHOTOCHROMIC OPTICAL ARTICLE
Abstract
A photochromic optical article comprises a substrate, and a
photochromic coating coated on an outer surface of the substrate
and having at least two photochromic layers. Each of the
photochromic layers has a composition that contains a carrier and
at least one photochromic dye. The compositions of the photochromic
layers are different from each other.
Inventors: |
Wang; Yun-Cheng; (Yuanli
Town, TW) ; Wang; Yi-Tang; (Yonghe City, TW) |
Correspondence
Address: |
TOWNSEND AND TOWNSEND AND CREW, LLP
TWO EMBARCADERO CENTER, EIGHTH FLOOR
SAN FRANCISCO
CA
94111-3834
US
|
Assignee: |
DARWIN OPTICAL CO., LTD.
Taichung
TW
|
Family ID: |
43531971 |
Appl. No.: |
12/541089 |
Filed: |
August 13, 2009 |
Current U.S.
Class: |
359/241 |
Current CPC
Class: |
G02B 5/23 20130101; G02C
2202/16 20130101; G02C 7/102 20130101 |
Class at
Publication: |
359/241 |
International
Class: |
G02F 1/23 20060101
G02F001/23; G02B 1/10 20060101 G02B001/10 |
Claims
1. A photochromic optical article comprising: a substrate; and a
photochromic coating coated on an outer surface of the substrate
and having at least two photochromic layers, each of the
photochromic layers having a composition that contains a carrier
and at least one photochromic dye, the compositions of the
photochromic layers being different from each other; wherein the
photochromic dyes of the photochromic layers are the same, the
carriers of the photochromic layers being the same, the
compositions for the photochromic layers being different in weight
ratio of the photochromic dye to the carrier; wherein the weight
ratio of the photochromic dye to the carrier decreases from an
innermost one of the photochromic layers that is nearest to the
outer surface of the substrate to an outermost one of the
photochromic layers that is farthest from the outer surface of the
substrate.
2. The photochromic optical article of claim 1, wherein the
substrate is made of a material selected from the group consisting
of glass, ceramics, and plastic.
3. The photochromic optical article of claim 1, wherein the
substrate is made of a material selected from the group consisting
of polycarbonate (PC), polymethyl methacrylate (PMMA), allyl
diglycol carbonate resin, polyethylene terephthalate (PET),
polyvinyl alcohol (PVA), and nylon.
4. The photochromic optical article of claim 1, wherein the carrier
of each of the photochromic layers is made of a polymeric material
selected from the group consisting of polyurethane-based polymer,
polyurea urethane-based polymer, poly(meth)acrylic-based polymer,
aminoplast, epoxy-based polymer, ethyleneglycol bismethacrylate
polymer, ethoxylated phenol bismethacrylate polymer, urethane
acrylate polymer, polythiourethane polymer, cellulose acetate
butyrate (CAB), styrene polymer, and styrene-methyl methacrylate
copolymer.
5-7. (canceled)
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to an optical article, more
particularly to a photochromic optical article.
[0003] 2. Description of the Related Art
[0004] A carrier containing a photochromic dye(s) can undergo
change in color when exposed to light radiation, such as UV
radiation or sunlight, and returns to its original color when
removed from the light radiation. This phenomenon is known as a
photochromic effect. In general, the same photochromic dye(s)
present in different carriers will produce different colors,
different activated intensities, different color activating and
fading rates, etc. Further, different carriers have different
capacities for mixing with the same photochromic dye(s) so that a
dye-to-carrier weight ratio varies for different carriers and the
same photochromic dye(s). Methods of providing a photochromic
effect in the prior art have the following characteristics and
drawbacks:
[0005] 1. In one conventional method, a photochromic dye(s) is
directly mixed with a material of a target body, such as an
eyeglass lens, so that the target body contains the photochromic
dye(s). Commonly used materials for the eyeglass lens are allyl
diglycol carbonate (CR-39), polycarbonate, and other polymeric
materials with high refractive indices. A disadvantage of this
method is that it is unable to be used where the material of the
target body is not suitable for use as a carrier for the
photochromic dye(s). Even if the material of the target body can be
a photochromic dye carrier, it may not be the best carrier to allow
particular photochromatic dye(s) to achieve sufficiently fast rates
of color change and color fading, a sufficient darkness, or
satisfactory color.
[0006] 2. In another conventional method, a suitable polymer, such
as cellulose acetate butyrate, is selected as a carrier, and a
photochromic dye(s) is added to the selected polymer to make a
laminate. The laminate is then adhered to a polycarbonate lens to
form a photochromic lens. Although such a technique can resolve the
drawback of the aforementioned method that involves directly mixing
photochromic dye(s) with a target body, the steps involved therein
are complicated so that a high manufacturing cost and a high defect
rate result.
[0007] 3. To resolve the aforesaid drawbacks, the use of a coating
process to form a photochromic layer on a surface of a lens is
developed. Aside from allowing selection of a good carrier for the
photochromic dye(s), use of the techniques disclosed in these
patents is such that the manufacturing process is simplified, and
the manufacturing cost is minimized. However, while the original
color prior to color change and the resulting color after color
change are important factors that determine whether a photochromic
article is acceptable or not in the market, a single photochromic
dye, as is used in these patents, cannot ensure that such color
transformation characteristics will be achieved.
[0008] 4. Referring to FIG. 1, a photochromic article 9 includes
two different photochromic dyes (A, B). A polymeric material is
first selected as a carrier (X), after which a photochromic dye (A)
and a photochromic dye (B) are mixed with the polymer or prepolymer
carrier (X). The carrier (X) is then coated on a substrate 91 by a
coating process. After curing, a single photochromic layer 92 is
formed on the substrate 91. Since a photochromic dye demonstrates
different photochromic properties in different carriers, the
photochromic dyes (A, B) in the photochromic layer 92 may therefore
demonstrate different photochromic properties after mixing with the
carrier (X). Hence, the carrier (X) cannot be a suitable carrier
for both of the photochromic dyes (A) and (B).
[0009] 5. Referring to FIG. 2, a conventional method to increase
the activated color intensity of the photochromic article 9
involves increasing the thickness of the photochromic layer 92 or
increasing a weight ratio of photochromic dye to carrier. However,
a coating process cannot produce a very thick coating layer.
Further, if the coating layer is very thick, it easily shrinks
during a curing process so that the coating layer will be uneven or
produces an internal stress. Moreover, the weight ratio of
photochromic dye to carrier can be increased only within a limited
range. If the weight ratio of photochromic dye to carrier is
excessively large, not only is it not possible to intensify the
color, any color change at all may be rendered difficult.
SUMMARY OF THE INVENTION
[0010] Therefore, the object of the present invention is to provide
a photochromic optical article with enhanced photochromic
properties.
[0011] According to this invention, a photochromic optical article
comprises a substrate, and a photochromic coating coated on an
outer surface of the substrate and having at least two photochromic
layers. Each of the photochromic layers has a composition that
contains a carrier and at least one photochromic dye. The
compositions of the photochromic layers are different from each
other.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Other features and advantages of the present invention will
become apparent in the following detailed description of the
preferred embodiments of the invention, with reference to the
accompanying drawings, in which:
[0013] FIG. 1 is a sectional view of a conventional photochromic
optical article;
[0014] FIG. 2 is a sectional view of another conventional
photochromic optical article;
[0015] FIG. 3 is a sectional view of a photochromic optical article
according to the first preferred embodiment of the present
invention;
[0016] FIG. 4 is a sectional view of a photochromic optical article
according to the second preferred embodiment of the present
invention, wherein three photochromic layers have different
compositions; and
[0017] FIG. 5 is a view similar to FIG. 4, but illustrating a
photochromic coating having the same composition for three
photochromic layers.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] Before the present invention is described in greater detail,
it should be noted that the same reference numerals have been used
to denote like elements throughout the specification.
[0019] The photochromic optical article of the present invention
may be a lens (such as an eyeglass lens), a screen, a window, a
protective plate, etc., and may be an element having a special
function, such as a photochromic film/coating, a polarized lens, or
a colored lens. The photochromic optical article of the present
invention is not limited to the aforesaid disclosure.
[0020] Referring to FIG. 3, a photochromic optical article
according to the first preferred embodiment of the present
invention is shown to comprise a substrate 1 and a photochromic
coating 2.
[0021] The substrate 1 is a transparent or semi-transparent optical
element, and may be made of a glass material, a ceramic material,
or a plastic material, such as polycarbonate (PC),
polymethylmethacrylate (PMMA), allyl diglycol carbonate resin
(MasterCast 1 or MasterCast 2, or CR-39), polyethylene
terephthalate (PET), polyvinyl alcohol (PVA), nylon, etc. However,
the material of the substrate 1 is not limited to the aforesaid
disclosures.
[0022] The photochromic coating 2 is coated on an outer surface of
the substrate 1, and has two photochromic layers 21, 22. Each of
the photochromic layers 21, 22 has a composition that contains a
carrier (X, Y) and a photochromic dye (A, B). The compositions of
the photochromic layers 21, 22, in this embodiment, are different
from each other, i.e., the carrier (X) and the photo chromic dye
(A) of the photochromic layer 21 are different from the carrier (Y)
and the photochromic dye (B) of the photochromic layer 22. The
photochromic layer 21 is formed by mixing the photochromic dye (A)
and the carrier (X). The photochromic layer 22 is formed by mixing
the photochromic dye (B) and the carrier (Y). The photochromic
coating 2 is not limited to being coated on a single surface of the
substrate 1, and may be coated on both surfaces or one or more
parts of one or both surfaces of the substrate 1 as required.
[0023] The carrier (X, Y) of each photochromic layer 21, 22 is made
of a polymeric material selected from the group consisting of
polyurethane-based polymer, polyurea urethane-based polymer, poly
(meth) acrylic-based polymer, aminoplast, epoxy-based polymer,
ethyleneglycol bismethacrylate polymer, ethoxylated phenol
bismethacrylate polymer, urethane acrylate polymer,
polythiourethane polymer, cellulose acetate butyrate (CAB),
polystyrene, and styrene-methyl methacrylate copolymer.
[0024] The present invention is aimed at selecting suitable
carriers for different photochromic dyes. In this embodiment, the
photochromic dye (A) is mixed with the carrier (X), and the
photochromic dye (B) is mixed with the carrier (Y). The carrier (X)
is then coated onto the substrate 1 by a coating process, and is
then cured to form the photochromic layer 21. Afterwards, the
carrier (Y) is coated on the photochromic layer 21 by a coating
process, and is then cured to form the photochromic layer 22.
[0025] The mixing of the photochromic dyes (A, B) with the
respective carriers (X, Y) is carried out through a conventional
method, such as direct mixing without using any solvent, or using a
solvent as a mixing medium. However, the mixing is not limited only
to such methods. The coating process may be any one of the
following conventional coating processes: dip coating, spin
coating, flow coating, spray coating, etc.
[0026] Further, according to the present invention, the color and
the activated color intensity required by the photochromic optical
article can be achieved by adjusting the thickness of the
photochromic layers 21, 22 or the weight ratio of the photochromic
dye (A, B) to the carrier (X, Y) of each photochromic layer 21,
22.
[0027] It is worth mentioning that each photochromic layer 21, 22
may include more than one kind of photochromic dye, and that the
kind of the photochromic dye (A) used in the photochromic layer 21
may be different from the kind of the photochromic dye (B) used in
the photochromic layer 22. Further, the number of the photochromic
dyes (A, B) need not correspond exactly to the number of the
photochromic layers 21, 22. That is, more than one kind of
photochromic dye may be present in a single photochromic layer. The
number of the photochromic layers required and the number of the
photochromic dyes to be added to each photochromic layer are
determined according to the color change requirement of the
photochromic optical article and the characteristics of the
photochromic dye.
[0028] Moreover, in the present invention, a primer (not shown) may
be coated between the photochromic layers 21, 22 or between the
photochromic layer 21 and the substrate 1 as required so as to
improve surface characteristics therebetween (such as the adhesion
force therebetween).Also, a protective layer may be added to an
outer surface of the photochromic layer 22 as required so as to
isolate the photochromic layer 22 from the outside environment, so
that the photochromic properties of the present invention are not
affected by exposure to the outside environment. If necessary,
other coatings, such as a hard coating, a tint coating, an
anti-reflection coating, an anti-fog coating, waterproof coating,
an anti-static coating, and an anti-radiation coating may be added
to the outer surface of the photochromic layer 22.
[0029] Referring to FIG. 4, there is shown a photochromic optical
article according to the second preferred embodiment of the present
invention which differs from the first preferred embodiment in that
the photochromic coating 2 has three photochromic layers 21, 22,
23. The photochromic layers 21, 22, 23 have the same photochromic
dye (A) and the same carrier (Z). However, the compositions for the
photochromic layers 21, 22, 23 are different in weight ratio of the
photochromic dye (A) to the carrier (Z). The weight ratio of the
photochromic dye (A) to the carrier (Z) decreases from an innermost
photochromic layer 21 that is nearest to the outer surface of the
substrate 1 to an outermost photochromic layer 23 that is farthest
from the outer surface of the substrate 1. The thickness of each
photochromic layer 21, 22, 23 is about one-third of that of the
conventional photochromic layer 92 shown in FIG. 2.
[0030] Referring to FIG. 5, if a photochromic optical article 3
includes three photochromic layers 31, 32, 33 which have the same
photochromic dye and the same carrier as the photochromic layers
21, 22, 23 shown in FIG. 4, but are provided with the same weight
ratio of the photochromic dye to the carrier, the following
problems will arise:
[0031] When the photochromic optical article 3 is irradiated by
ultraviolet (UV) light, the UV light rays first pass through the
outermost photochromic layer 33 so that it changes color. Since the
remaining UV light rays then pass consecutively through the
photochromic layers 32, 31, the photochromic layer 31 receives the
smallest amount of UV light rays. In this situation, because the
same weight ratio of the photochromic dye to the carrier is used in
each photochromic layer 31, 32, 33, the amount of the photochromic
dye activated by the UV light is the smallest in the photochromic
layer 31 so that the activated color intensity thereof cannot be as
good as that of the photochromic layer 33.
[0032] In case the weight ratio of the photochromic dye to the
carrier is increased in order to increase the activated color
intensity as in the prior art, this will help only to a certain
point, past which further increases in the weight ratio will result
in waste of the photochromic dye (C). Similarly, if the thickness
of the photochromic coating 30 or the photochromic layer 31 is
increased as in the prior art, this will result in waste of the
coating liquid after the thickness reaches a certain high level.
This is why in the prior art shown in FIG. 2, the activated color
cannot be intensified or the color cannot be easily changed.
[0033] Referring back to FIG. 4, in the present invention, in order
to effectively increase the activated color intensity, the weight
ratio of the photochromic dye (A) to the carrier (Z) is decreased
as the distance from the outer surface of the substrate 1 is
increased, so that the photochromic dye (A) in the photochromic
layers 21, 22, 23 can be fully utilized and will not be wasted.
Since varying the weight ratio of the photochromic dye to the
carrier is difficult for a single layer photochromic coating, the
present invention employs a multi-layered structure for the
photochromic coating 2 including the photochromic layers 21, 22, 23
to achieve this purpose. The weight ratios of the photochromic dye
(A) to the carrier (Z) in the photochromic layers 21, 22, 23 are
sequentially reduced from the innermost photochromic layer 21 to
the outermost photochromic layer 23 in order to thereby increase
the activated color intensity of the photochromic coating 2.
Therefore, even if the total amount of the photochromic dye (A)
used in the present invention is similar to that of the
photochromic dye in the photochromic layer 92 shown in FIG. 2, a
higher activated color intensity can be achieved in the present
invention.
[0034] While three photochromic layers are used in this embodiment,
the present invention is not limited only thereto. Two or more
photochromic layers may be employed according to the present
invention. Further, each photochromic layer may have one or more
kinds of photochromic dyes. The thicknesses of the photochromic
layers may also differ. Further, as long as the photochromic dyes
in the layers can be fully activated and utilized, the photochromic
layers should not be limited to the same carrier.
[0035] While the present invention has been described in connection
with what are considered the most practical and preferred
embodiments, it is understood that this invention is not limited to
the disclosed embodiments but is intended to cover various
arrangements included within the spirit and scope of the broadest
interpretations and equivalent arrangements.
* * * * *