U.S. patent application number 14/851276 was filed with the patent office on 2016-01-07 for bi-layer adhesive for lens lamination.
The applicant listed for this patent is Essilor International (Compagnie Generale d'Optique). Invention is credited to ARNAUD GLACET, PEIQI JIANG, BRUCE KEEGAN.
Application Number | 20160002504 14/851276 |
Document ID | / |
Family ID | 41445670 |
Filed Date | 2016-01-07 |
United States Patent
Application |
20160002504 |
Kind Code |
A1 |
GLACET; ARNAUD ; et
al. |
January 7, 2016 |
Bi-Layer Adhesive for Lens Lamination
Abstract
A bi-layer adhesive and a method for laminating a film onto an
optical article utilizing the bi-layer adhesive are described. A
method for laminating the film onto an optical article and the
bi-layer adhesive for use in the method are also described. The
bi-layer adhesive includes a latex adhesive layer and an HMA layer
sequentially disposed on the film and dried to form a solid layer
of uniform thinness throughout to provide optical quality. Various
types of films may be employed to provide an optical function.
Following optional pre-treatment steps, the bi-layer adhesive is
coated on to the film. An optical hot press technique is used to
deliver heat and pressure over a short period of time to form a
functionally-enhanced optical article with high adhesive
strength.
Inventors: |
GLACET; ARNAUD; (Clearwater,
FL) ; JIANG; PEIQI; (Tarpon Springs, FL) ;
KEEGAN; BRUCE; (Seminole, FL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Essilor International (Compagnie Generale d'Optique) |
Charenton-le-Pont |
|
FR |
|
|
Family ID: |
41445670 |
Appl. No.: |
14/851276 |
Filed: |
September 11, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12264376 |
Nov 4, 2008 |
9132594 |
|
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14851276 |
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Current U.S.
Class: |
428/174 ;
428/336; 428/412; 428/423.3 |
Current CPC
Class: |
G02B 1/041 20130101;
Y10T 156/1002 20150115; Y10T 428/265 20150115; C09J 175/04
20130101; Y10T 428/2896 20150115; Y10T 428/31551 20150401; B29D
11/0073 20130101; Y10T 428/2878 20150115; C09J 119/02 20130101;
Y10T 428/28 20150115; G02B 5/3041 20130101 |
International
Class: |
C09J 119/02 20060101
C09J119/02; G02B 1/04 20060101 G02B001/04; G02B 5/30 20060101
G02B005/30; C09J 175/04 20060101 C09J175/04 |
Claims
1. A functionalized optical element comprising: an optical base
element; and a functionalized layered structure glued directly to
the optical base element, the functionalized layer structure
incorporating at least one functional layer to form a
functionalized optical element, the functionalized layer structure
as the functionalized optical element further comprising a bi-layer
adhesive structure, the bi-layer adhesive structure comprising: a
layer of latex adhesive disposed on a surface of said
functionalized layered structure and bonding strongly to the at
least one functional layer; and a layer of hot melt adhesive (HMA)
disposed between the layer of latex adhesive and the optical base
element, a polymer for forming the layer of HMA comprising only a
thermoplastic polymer, the bi-layer adhesive structure forming a
uniformly thin bi-layer of an optical quality permanently bonding
the functionalized layered structure on the optical base element
while maintaining optical quality, each of the layer of latex
adhesive and the layer of HMA comprising a different adhesive to
address disparate material properties of the least one functional
layer and the optical base element.
2. The functionalized optical element of claim 1, wherein said
layer of latex adhesive comprises a material selected from the
group consisting of an acrylic latex, a (meth)acrylic latex, a
polyurethane latex, a core/shell latex, and combinations
thereof.
3. The functionalized optical element of claim 2, wherein said
layer of latex adhesive comprises a dry, solid layer of between 0.5
microns and 10 microns thick with a substantially uniform thickness
throughout to provide the optical quality.
4. The functionalized optical element of claim 2, wherein said
layer of latex adhesive comprises a dry, solid layer of between 1.0
microns and 5.0 microns thick with a substantially uniform
thickness varying by less than 0.3 microns to provide the optical
quality.
5. The functionalized optical element of claim 1, wherein said
layer of HMA is formed from a starting material selected from one
or more of a group consisting of a UV curable HMA, a UV curable
monomer, a thermal curable HMA, and a thermal curable monomer.
6. The functionalized optical element of claim 1, wherein said
layer of HMA further comprises one or more of an HMA polymer, and a
colloid.
7. The functionalized optical element of claim 1, wherein said
layer of HMA is formed from a polyurethane HMA.
8. The functionalized optical element of claim 7, wherein the layer
of HMA comprises a dry, solid layer between 1.0 microns and 20
microns with a substantially uniform thickness throughout to
provide the optical quality.
9. The functionalized optical element of claim 8, wherein the layer
of HMA comprises a dry, solid layer between 1.5 microns and 10
microns with a substantially uniform thickness varying by less than
0.3 microns to provide the optical quality.
10. The functionalized optical element of claim 1, wherein the
functionalized layered structure includes one or more layers
selected from the group consisting of: an optical function layer;
an optical structured layer; a Fresnel lens structure; a
performance function layer; a polarizing layer; a photochromic
layer; a hard coat layer; a top coat layer; an anti-fog layer; an
anti-smudge layer; an anti-reflective layer; and an anti-static
layer.
11. The functionalized optical element of claim 1, wherein the
functionalized layered structure includes one of a polarizing film,
a TAC/PVA/TAC polarizing film and a PET polarizing film.
12. The functionalized optical element of claim 1, wherein the
optical base element is a thermoplastic optical base element
selected from the group consisting of a finished lens, a
semi-finished lens, a PAL lens, an afocal lens, a plano lens, a
unifocal lens, and a multifocal lens.
13. The functionalized optical element of claim 1, wherein the
optical base element is a thermoset optical base element selected
from the group consisting of a finished lens, a semi-finished lens,
a PAL lens, an afocal lens, a plano lens, a unifocal lens and a
multifocal lens.
14. The functionalized optical element of claim 1, wherein the
optical base element is a polycarbonate lens, wherein the
functionalized layered structure includes a polarizing film,
wherein the layer of latex adhesive is a polyurethane latex
adhesive, and wherein the layer of HMA is a polyurethane HMA, which
collectively form a laminated polarized ophthalmic lens.
15. (canceled)
16. The functionalized optical element of claim 1, wherein the
optical base element has a base curve, and prior to bonding with
the functionalized layer structure, the functionalized layered
structure has a curve that is close to the base curve.
17. The functionalized optical element of claim 1, wherein the
functionalized layered structure includes at least one treated
surface.
18. (canceled)
19. (canceled)
20. (canceled)
21. The functionalized optical element of claim 1, wherein said
layer of latex adhesive is a polyurethane latex adhesive dried to a
final dry thickness of between 1.0 microns and 5.0 microns, said
layer of HMA is a polyurethane HMA dried to a final dry thickness
of between 1.5 microns and 10 microns, and the bi-layer adhesive
structure has the optical quality and uniform thickness varying by
less than 0.3 microns.
22. (canceled)
23. (canceled)
24. (canceled)
25. (canceled)
26. The functionalized optical element of claim 1, wherein the
optical base element is a polycarbonate lens, and the
functionalized layered structure includes a polarizing film which
collectively form a laminated polarized ophthalmic lens.
27. The functionalized optical element of claim 1, wherein the
layer of latex adhesive is formed from a thermoset material.
28. The functionalized optical element of claim 1, wherein the
bi-layer adhesive structure provides both good dry adhesion and
good wet adhesion to the functionalized optical element when formed
with the optical base element and the functionalized layered
structure.
29. The functionalized optical element of claim 1, wherein the
bi-layer adhesive structure is a structure operable with film
lamination, in which film lamination is utilized to form the
functionalized optical element, the bi-layer adhesive being less
susceptable to defects from the film lamination as compared with a
comparative functionalized optical element formed without the
bi-layer structure.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional patent application of U.S.
patent application Ser. No. 12/264,376 filed Nov. 4, 2008, which
issued as U.S. Pat. No. 9,132,594 on Sep. 15, 2015, the entirety of
which is incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The invention relates to a method for laminating a
functionalized layered structure to an optical base element with a
bi-layer adhesive and the resulting functionalized optical
element.
BACKGROUND
[0003] Various films and coatings are combined with optical
elements to enhance their performance. Adhesion between polarized
films and plastic lenses has been a long standing problem within
the industry. The selection of one adhesive always represents a
compromise between ease of use, mechanical integrity and optical
quality.
[0004] One approach is detailed in WO 2006/082105, which employs a
latex glue in a film transfer process. In EP 1868798, an HMA glue
for a film transfer process is described. In WO 2007/096521, a
polarized film is laminated with a pressure sensitive adhesive. In
a mechanical approach described in US Publication No. 2007/0195262,
a complex support is used to warp the film during lamination to
improve adhesion.
[0005] However, the techniques previously disclosed have a number
of drawbacks, mainly due to low adhesion or low mechanical
performance. Attempts to cure these defects have marginally
improved adhesion strength with a loss of optical quality.
Accordingly, there is a need to provide a method of adhesive
application which compensates for the different material properties
of the film and lens surface to provide high adhesive strength in a
basic lamination process.
SUMMARY
[0006] It is therefore an object as described herein to improve
both the mechanical and optical properties of laminated
functionalized optical elements.
[0007] It is a further object to present two different adhesives
and methods for applying same to provide a bi-layer adhesive that
can be readily employed in a variety of optical hot press
methods.
[0008] It is another object to apply the different adhesives in
such a manner as to form a uniformly thin layer at optical
quality.
[0009] These and other objects described herein are achieved by a
functionalized optical element that includes an optical base
element and a functionalized layered structure incorporating at
least one functional layer which is glued directly to the optical
base element to form a functionalized optical element. A bi-layer
adhesive structure is disposed between the optical base element and
the functionalized layered support. The bi-layer adhesive structure
includes a layer of latex adhesive disposed on a surface of said
functionalized layered structure and a layer of hot melt adhesive
disposed between the latex layer and the optical base element to
form a bi-layer adhesive that permanently retains the
functionalized layered structure on the optical base element while
maintaining optical quality.
[0010] The latex adhesive layer comprises a material selected from
the group consisting of an acrylic latex, a (meth)acrylic latex, a
polyurethane latex, a core/shell latex, and combinations thereof.
The latex layer comprises a dry, solid layer of between 0.5 microns
and 10 microns thick with a uniform thickness throughout to provide
optical quality. In some preferred embodiments, the latex layer is
between 1.0 microns and 5.0 micron thick with a uniform thickness
varying by less than 0.3 microns throughout to provide optical
quality.
[0011] The hot melt adhesive (HMA) layer includes one or more of a
UV curable HMA, a UV curable monomer, a thermal curable HMA, a
thermal curable monomer, a polymer HMA, a thermoplastic polymer
HMA, and a colloid. In some preferred embodiments, the HMA is a
polyurethane HMA. The HMA layer comprises a dry, solid layer
between 1.0 micron and 20 microns with a uniform thickness
throughout to provide optical quality. In a preferred embodiment
the HMA layer is between 1.5 microns and 10 microns with a uniform
thickness varying by less than 0.3 microns throughout to provide
optical quality.
[0012] Various types of functionalized layered structure includes
one or more layers selected from the group consisting of: an
optical function layer; an optical structured layer; a Fresnel lens
structure; a performance function layer; a polarizing layer; a
photochromic layer; a hard coat layer; a top coat layer; an
anti-fog layer; an anti-smudge layer; an anti-reflective layer; and
an anti-static layer. In a preferred embodiment, the functionalized
layered structure includes one of a polarizing film, a TAC/PVA/TAC
polarizing film and a PET polarizing film.
[0013] The optical base element is a thermoplastic or thermoset
optical base element selected from the group consisting of a
finished lens, a semi-finished lens, a PAL lens, an afocal lens, a
plano lens, a unifocal lens, and a multifocal lens.
[0014] One or more preferred ensembles include an optical base
element comprising a polycarbonate lens, and wherein the
functionalized layered structure includes a polarizing film and
wherein the latex adhesive is a polyurethane latex adhesive, and
wherein the HMA is a polyurethane HMA, which collectively form a
laminated polarized ophthalmic lens.
[0015] Another aspect as described herein includes a method for
manufacturing a functionalized optical element comprising the
following steps. An optical base element and a functionalized
layered structure that include at least one functional layer are
provided. A layer of latex adhesive is firstly coated onto one
surface of said functionalized layered structure. A layer of
hot-melt adhesive is secondly coated onto the dried latex adhesive
layer to form a uniformly thin bi-layer adhesive lamina of optical
quality. The functionalized layered structure is hot pressed
against the optical base element with the second HMA coating layer
in contact with a surface of the optical base element to form a
functionalized optical element with high adhesive strength.
[0016] The functionalized layered structure is thermoformed to a
curve that is close to the base curve of the optical base element,
prior to lamination. An additional pre-treatment step may include
surface treating the functionalized layered structure with a corona
discharge.
[0017] The first coating step comprises spin coating a liquid
polyurethane latex adhesive to a final dry thickness of between 0.5
microns and 10 microns. The second coating step comprises spin
coating a liquid polyurethane HMA to a final dry thickness of
between 1 micron and 20 microns. The laminated functionalized
optical element may be exposed to heat and UV radiation.
[0018] In a preferred embodiment, the first coating step comprises
spin coating a liquid polyurethane latex adhesive to a final dry
thickness of between 1.0 microns and 5.0 microns; and wherein said
second coating step comprises spin coating a liquid polyurethane
HMA to a final dry thickness of between 1.5 microns and 10 microns
to provide a bi-layer adhesive lamina at optical quality with a
uniform thickness varying by less than 0.3 microns across the
surface. In a preferred embodiment, the optical base element is a
polycarbonate lens, and wherein the functionalized layered
structure includes a polarizing film, which, collectively, form a
laminated polarized ophthalmic lens.
[0019] In additional embodiments, described herein is a method for
manufacturing a functionalized optical element. The method
comprises providing an optical base element. The method also
comprises providing a functionalized layered structure that
includes at least one functional layer, such that the
functionalized layered structure adheres to the optical base
element. The providing includes the steps of applying a first
coating as a layer of latex adhesive onto one exposed surface of
the at least one functional layer, drying said first coating
thereby forming a dried latex adhesive layer which bonds strongly
to the at least one functional layer, applying a second coating as
a layer of hot-melt adhesive (HMA) onto the dried latex adhesive
layer to form a uniformly thin bi-layer adhesive lamina of optical
quality, wherein a polymer for forming the HMA layer includes only
a thermoplastic polymer, drying the second coating applied as the
HMA layer before hot pressing, each of the first coating and the
second coating comprising a different adhesive layer, and upon
preparing the bi-layer adhesive lamina, hot pressing the
functionalized layered structure against the optical base element
with the bi-layer adhesive lamina therebetween, whereby the second
coating formed as a dried HMA layer bonds with the optical base
element, the bi-layer adhesive lamina forming a functionalized
optical element, such that a high adhesive strength is thereby
provided between the optical base element and the functionalized
layered structure by using the latex adhesive and the HMA layer in
combination to form the bi-layer adhesive lamina to address
disparate material properties between the at least one functional
layer and the optical base element. The optical base element may
have a base curve, and prior to applying said first coating, the
method may further include thermoforming the functionalized layered
structure to a curve that is close to a base curve. Prior to
applying said first coating, the method may further include surface
treating the functionalized layered structure with a corona
discharge. Applying said first coating may comprise spin coating a
liquid polyurethane latex adhesive to a final dry thickness of
between about 0.5 microns and about 10 microns. Applying said
second coating may comprise spin coating a liquid polyurethane HMA
to a final dry thickness of between 1 micron and 20 microns. The
method may further include exposing the functionalized optical
element to UV radiation. Applying said first coating may comprise
spin coating a liquid polyurethane latex adhesive to a final dry
thickness of between 1.0 microns and 5.0 microns and wherein
applying said second coating may comprise spin coating a liquid
polyurethane HMA to a final dry thickness of between 1.5 microns
and 10 microns to provide a bi-layer adhesive lamina at optical
quality with a uniform thickness varying by less than 0.3 microns.
The functionalized layered structure may include one or more layers
selected from the group consisting of an optical function layer, an
optical structured layer, a Fresnel lens structure, a performance
function layer, a polarizing layer, a photochromic layer, a hard
coat layer, a top coat layer, an anti-fog layer, an anti-smudge
layer, an anti-reflective layer, and an anti-static layer. The
functionalized layered structure may include a polarizing film. The
optical base element may be a thermoplastic optical base element
selected from the group consisting of a finished lens, a
semi-finished lens, a PAL lens, an afocal lens, a plano lens, a
unifocal lens, and a multifocal lens. The optical base element may
be a thermoset optical base element selected from the group
consisting of a finished lens, a semi-finished lens, a PAL lens, an
afocal lens, a plano lens, a unifocal lens, and a multifocal lens.
The optical base element may be a polycarbonate lens, and the
functionalized layered structure may include a polarizing film
which collectively form a laminated polarized ophthalmic lens. The
HMA may be selected from the group consisting of polyolefins,
polystyrene block elastomers, polyisoprene block elastomers,
ethylene-butylene copolymer block elastomers, polyamides,
polyurethanes, polyurethane-ureas, polyvinylpyrrolidones,
polyesters, polyesteramides, poly(oxazolines) and poly(meth)
acrylic systems. The HMA may be a polyurethane-based HMA. The HMA
may be UV curable. The second coating may have a final dry
thickness of between 1.5 microns and 10 microns, in which there is
a small variation in thickness that is less than 0.3 microns and
1.0 microns, respectively. Drying said first coating may include an
introduction of heat. Drying the second coating may include an
introduction of heat. Hot pressing the functionalized layered
structure against the optical base element with the bi-layer
adhesive lamina therebetween may further comprise exposing to UV
radiation. The first coating may form a thermoset layer.
[0020] In still further embodiments are described a functionalized
optical element comprising an optical base element and a
functionalized layered structure glued directly to the optical base
element. The functionalized layer structure incorporates at least
one functional layer to form a functionalized optical element. The
functionalized layer structure as the functionalized optical
element further comprises a bi-layer adhesive structure. The
bi-layer adhesive structure comprises a layer of latex adhesive
disposed on a surface of said functionalized layered structure and
bonding strongly to the at least one functional layer; and a layer
of hot melt adhesive (HMA) disposed between the layer of latex
adhesive and the optical base element. T polymer for forming the
layer of HMA may comprise only a thermoplastic polymer. The
bi-layer adhesive structure forms a uniformly thin bi-layer of an
optical quality permanently bonding the functionalized layered
structure on the optical base element while maintaining optical
quality. Each of the layer of latex adhesive and the layer of HMA
comprise a different adhesive to address disparate material
properties of the least one functional layer and the optical base
element. The layer of latex adhesive may comprise a material
selected from the group consisting of an acrylic latex, a
(meth)acrylic latex, a polyurethane latex, a core/shell latex, and
combinations thereof. The layer of latex adhesive may comprise a
dry, solid layer of between 0.5 microns and 10 microns thick with a
substantially uniform thickness throughout to provide the optical
quality. The layer of latex adhesive may comprise a dry, solid
layer of between 1.0 microns and 5.0 microns thick with a
substantially uniform thickness varying by less than 0.3 microns to
provide the optical quality. The layer of HMA may be formed from a
starting material selected from one or more of a group consisting
of a UV curable HMA, a UV curable monomer, a thermal curable HMA,
and a thermal curable monomer. The layer of HMA may further
comprise one or more of an HMA polymer and a colloid. The layer of
HMA may be formed from a polyurethane HMA. The layer of HMA may
comprise a dry, solid layer between 1.0 microns and 20 microns with
a substantially uniform thickness throughout to provide the optical
quality. The layer of HMA may comprise a dry, solid layer between
1.5 microns and 10 microns with a substantially uniform thickness
varying by less than 0.3 microns to provide the optical quality.
The functionalized layered structure may include one or more layers
selected from the group consisting of: an optical function layer;
an optical structured layer; a Fresnel lens structure; a
performance function layer; a polarizing layer; a photochromic
layer; a hard coat layer; a top coat layer; an anti-fog layer; an
anti-smudge layer; an anti-reflective layer; and an anti-static
layer. The functionalized layered structure may include one of a
polarizing film, a TAC/PVA/TAC polarizing film and a PET polarizing
film. The optical base element may be a thermoplastic optical base
element selected from the group consisting of a finished lens, a
semi-finished lens, a PAL lens, an afocal lens, a plano lens, a
unifocal lens, and a multifocal lens. The optical base element may
be a thermoset optical base element selected from the group
consisting of a finished lens, a semi-finished lens, a PAL lens, an
afocal lens, a plano lens, a unifocal lens and a multifocal lens.
The optical base element may be a polycarbonate lens, the
functionalized layered structure may include a polarizing film, the
layer of latex adhesive may be a polyurethane latex adhesive, and
the layer of HMA may be a polyurethane HMA, which collectively form
a laminated polarized ophthalmic lens. The optical base element may
have a base curve, and prior to bonding with the functionalized
layer structure, the functionalized layered structure has a curve
that is close to the base curve. The functionalized layered
structure may include at least one treated surface. The layer of
latex adhesive may be a polyurethane latex adhesive dried to a
final dry thickness of between 1.0 microns and 5.0 microns, said
layer of HMA may be a polyurethane HMA dried to a final dry
thickness of between 1.5 microns and 10 microns, and the bi-layer
adhesive structure having the optical quality may have a uniform
thickness varying by less than 0.3 microns. The optical base
element may be a polycarbonate lens, and the functionalized layered
structure includes a polarizing film which collectively form a
laminated polarized ophthalmic lens. The layer of latex adhesive
may be formed from a thermoset material. The bi-layer adhesive
structure provides both good dry adhesion and good wet adhesion to
the functionalized optical element when formed with the optical
base element and the functionalized layered structure. The bi-layer
adhesive structure may be a structure operable with film
lamination, in which film lamination is utilized to form the
functionalized optical element, the bi-layer adhesive being less
susceptible to defects from the film lamination as compared with a
comparative functionalized optical element formed without the
bi-layer structure.
[0021] These and other embodiments are described herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The advantages, nature, and various additional features of
the invention will appear more fully upon consideration of the
illustrative embodiments now to be described in detail in
connection with accompanying drawing:
[0023] FIG. 1 is a flowchart showing various steps according to an
embodiment of the lamination method as described herein.
DESCRIPTION
[0024] In the manufacture and customization of optical elements,
the properties of the optical base element are frequently enhanced
by laminating a functionalized layered structure onto a surface of
the optical base element. Within the category of adhesive based
lamination methods, various techniques have been proposed which
include a single layer of thermal curable glue, UV curable glue,
hot melt adhesives (HMA) or pressure sensitive adhesives (PSA). All
of the prior art techniques have either optical or mechanical
performance issues due to un-even thickness of the glue layer, a
lack of good adhesion or low mechanical properties of the adhesive
layer.
[0025] The principle of the embodiments described herein is to use
a bi-layer adhesive that is applied to the functionalized layered
structure in stages before laminating to the lens. The first
adhesive layer is latex which can bond strongly to the
functionalized layered structure. The second adhesive layer is a
hot melt adhesive (HMA) which can bond strongly to the lens. By
using the combination of these two layers, the functionalized
layered structure can be strongly bonded to the lens by a variety
of methods in a very short time. The latex and HMA layers can be
applied to the functionalized layered support in liquid form, for
example, via spin coating or dip coating, to obtain a very thin,
and uniformly thick adhesive layer of optical quality. To improve
the adhesion between the latex and the functionalized layered
support, optional pre-treatment steps can be performed, such as
corona or caustic treatment. The functionalized layered support may
be thermoformed to a shape close to the base curve of the optical
base element. In addition, the surface of the functionalized
layered support may be subjected to a corona discharge
treatment.
[0026] The bi-layer adhesive is useful in laminating to optical
base elements made from plastic which could be thermoplastic or
thermoset material. The base elements could be made from any
suitable optical thermoset material including polyurethanes, CR-39,
and high index polyurethanes, for example 1.67 and 1.74 materials.
An exemplary list of plastics includes polycarbonate, polyamide,
polyimide, polysulfone, copolymers of polyethyleneterephthalate and
polycarbonate, polyolefin, homopolymers and copolymers of
diethylene glycol bis(allylcarbonate), homopolymers and copolymers
of (meth)acrylic monomers, homopolymers and copolymers of
thio(meth)acrylic monomers, homopolymers and copolymers of
urethane, homopolymers and copolymers of thiourethane, epoxy
homopolymers and copolymers, and episulfur homopolymers and
copolymers. In a preferred embodiment the optical base element
comprises an injection molded thermoplastic lens, for example,
polycarbonate.
[0027] The bi-layer adhesive is useful in laminating to either the
convex or the concave side of optical base elements, for example,
ophthalmic lenses. The lenses may be sunglasses, plano lenses,
visors, or prescription (Rx) lenses. Such lenses may include
finished lenses (F), semi-finished lenses (SF), progressive
addition lenses (PAL), multifocal lenses, unifocal lenses and
afocal lenses. The optical base element may be clear, tinted or
dyed.
[0028] The functionalized layered support may comprise a film or
coating that contributes an optical or performance function to the
optical base element. In addition, the functionalized layered
support may comprise a multi-functional film or coating that
contributes at least one optical function, at least one performance
function, or combinations thereof. Examples of optical functions
include polarizing and photochromically enabling optical elements.
Such functions are realized by polarized films, microstructured
films as described for example in WO 2006/013250, photochromic
films and photochromic coatings. Polarizing materials are
commercially available as polyethyleneterephthalate film (PET) or
polyvinylacetate film (PVA) encapsulated by two cellulose films of
two major types: cellulose triacetate (TAC) films and cellulose
acetate butyrate (CAB) films. Other functionalized layer films
could be PET which bear an antireflective coating, hard coat, or
any other top-coat, such as an antistatic coating, anti-fog or
anti-smudge coating, and a polarized coating or layers. In a
preferred embodiment described herein, a polarizing film is adhered
to an optical base element to provide a polarized lens.
[0029] Examples of performance functions include hard coating,
impact resistant, anti-fog, anti-static, anti-smudge and
anti-reflective. Such functions are realized in the form of hard
multi-coat (HMC) films which have several layers capped by a top
coat film.
[0030] The functionalized layered element will have one surface
designated for contact with the optical base element. Following any
optional pre-treatment steps, this contact surface will receive a
layer of latex adhesive, applied so as to achieve optical quality
and good bond to the functionalized layered element. The various
application processes shall be described in greater detail below.
The application step involves drying the latex layer so that a
thin, solid layer of latex remains. The dried latex layer shall be
of sufficient purity to display color, transmission and clarity at
a level consistent with optical quality ophthalmic lenses. In
addition, the latex layer shall possess a uniform thickness across
its surface. Uniform thickness refers to a layer which has a
consistent thickness that varies by less than 0.01 microns to 0.3
microns. According to the description presented herein, the latex
layer shall be applied to a thickness of between about 0.5 and
about 10 microns. In a preferred embodiment, the latex layer shall
have a thickness of between 1.0 microns to 5.0 microns. For layers
about 0.5 microns thick, the variation in thickness should be less
than 0.05 microns. For layers about 5.0 microns thick, the
variation in thickness should be less than 0.3 micron.
[0031] Latex materials meeting such requirements that may be used
as described herein include polyurethane latex, acrylic latex, and
core/shell latex. For example, (meth)acrylic such as acrylic
latexes commercialized under the name Acrylic latex A-639 by
Zeneca, polyurethane latexes such as the latexes commercialized
under the names W-213, W-240 and W-234 by Baxenden, and a
polyurethane latex based on this commercialized product.
Preferably, polyurethane latexes are utilized in the practice of
the one or more embodiments described herein and more particularly
such latexes as described in U.S. Pat. No. 5,316,791. Other
preferred latexes are core/shell latexes such as those described in
U.S. Pat. No. 6,503,631 and U.S. Pat. No. 6,489,028. Other
preferred latexes are alkyl(meth)acrylates, such as butylacrylate
and butyl(meth) acrylate.
[0032] The latex materials may optionally be blended with additives
to adjust the rheological, mechanical or optical properties
thereof. For example, a coupling agent may be added to the latex
material to promote adhesion to the functionalized layered support.
The latex material may include a cosmetic or photochromic dye or
color dye or functional materials, such as anti-static materials,
for example, as described in EP 1161512, U.S. Pat. No. 6,770,710
and U.S. Pat. No. 6,740,699.
[0033] Second HMA Layer. After the latex layer is dry, solid and
stable, a hot melt adhesive (HMA) material is applied over the
latex layer, in a manner to achieve optical quality. The various
application processes shall be described in greater detail below.
The application step involves drying the HMA so that a thin, solid
layer of HMA remains. The dried HMA layer shall be of sufficient
purity to display color, transmission and clarity at a level
consistent with optical quality ophthalmic lenses. In addition, the
HMA layer shall possess a uniform thickness across its surface.
Uniform thickness refers to a layer which has a consistent
thickness that varies by less than 0.05 microns to 0.3 microns. As
described herein, the HMA layer shall be applied to a thickness of
between about 1.0 and about 30 microns. In a preferred embodiment,
the latex layer shall have a thickness of between 1.5 microns to 15
microns. For layers about 1.5 microns thick, the variation in
thickness should be less than 0.3 microns. For layers about 10.0
microns thick, the variation in thickness should be less than 1.0
micron.
[0034] HMA materials meeting such requirements that may be used as
described herein include polyurethane based HMA materials. These
materials are characterized as aqueous anionic dispersions of high
molecular weight polyurethane. One kind of HMA is commercially
available from Bayer, such as Dispercoll.RTM. U 42 and KA-8758. The
HMA materials may optionally be blended with additives to adjust
the rheological, mechanical or optical properties thereof. For
example, additives, such as colloid silica, can be added to the HMA
formulation to facilitate crosslinking to improve the hardness and
durability. A suitable colloid could be LUDOX.RTM. SM-30 colloidal
silica, 30 wt. % suspension in water. The percentage of colloid in
HMA could be in the range of 1-20 wt. % and with a preferred range
of 2-10 wt. %. The HMA materials utilized herein as described can
also be any known polymer for formulating a hot melt adhesive, but
is preferably a thermoplastic polymer. Thus, an HMA polymer can be
chosen amongst polyolefins, polyamides, polyurethanes,
polyurethane-ureas, polyvinylpyrrolidones, polyesters,
polyesteramides, poly(oxazolines) and poly(meth)acrylic systems.
Suitable polyolefins are disclosed in particular U.S. Pat. No.
5,128,388. Preferred polyolefins are block thermoplastic elastomers
such as block elastomers comprising polystyrene blocks,
polybutadiene blocks, polyisoprene blocks or ethylene-butylene
copolymer blocks. Besides, any kind of UV/thermal curable HMA or
HMA blend with UV/thermal curable monomers adhesive layers can be
utilized as described herein as a second adhesive layer.
[0035] The bi-layer adhesive according to embodiments described
herein comprises dry latex adhesive layer disposed between a
functionalized layered structure and a dry polyurethane HMA layer.
Under various processes that provide heat, pressure and time, the
bi-layer adhesive operates to adhere the functionalized layered
structure to an optical base element. The bi-layer adhesive
comprises a uniformly thin layer at optical quality. We refer to
this construct as a lamina, meaning an ultra thin layer composed of
two different adhesives with uniform thickness thereby providing
optical quality. The bi-layer adhesive provides a unique
combination of materials that address disparate material properties
between the functionalized layered structure and the optical base
element. The latex layer typically exhibits good adhesion to the
functionalized layered support, or to the optical base element in
one surface alone during wet coating and to dry stage. However, it
has poor adhesion to a lens when re-activated by heating and
pressure after drying on the TAC film. The HMA layer, in contrast,
has variable adhesive strength to lens when re-activated after
drying. But it does not have a good adhesion as the latex layer to
the film during wet and dry stage. More particularly, the many HMAs
have limited adhesive strength to the surface of the functionalized
layered structure. Surprisingly, it was discovered that treating
the functionalized layered structure with a latex adhesive primer
layer, the HMA would now have high adhesive strength on both the
lens and the functional film. Accordingly, the combination of the
latex layer and the HMA layer overcomes the problems associated
with adhering different materials together to provide a
functionalized optical element with both optical quality and high
mechanical strength.
[0036] As can be seen in the flowchart of FIG. 1, there are shown
various steps for the manufacturing of a functionalized optical
element. While one optional pre-processing step is shown, there may
be two or more pre-processing steps involved in a particular
embodiment described herein. Likewise, other steps may be
introduced at various stages and the claimed method is intended to
cover those in a non-limiting fashion.
[0037] In step 10, there is provided a functionalized layered
structure. The functionalized layered structure may have more than
one layer. The functionalized layered support can include a
combination of functional layers and non-functional layers. The
types and categories of functional layers are described above in a
non-limiting exemplary listing. An optical base element is also
provided. The types and categories of optical base elements are
described above in a non-limiting exemplary listing.
[0038] In step 13, optional pre-processing steps may be employed.
The functionalized layered structure may be pre-processed to
improve the adhesion of the latex adhesive thereto. For example,
the facing surface may be exposed to a corona discharge treatment.
Alternatively, or in addition, the functionalized layered structure
may be thermoformed to a curve that is similar to the base curve of
the facing surface of the optical base element. If thermoforming is
employed, the functionalized layered support will be thermoformed
to a curve within about 1 diopter of the base curve of the optical
base element. Both thermoforming and an adhesion improvement step
may be carried out, in any order.
[0039] Step 16 encompasses a latex adhesive application step to
deposit the latex material onto the functionalized layered
structure. Prior to application, an optional blending step 15 may
be provided. The latex material may be combined with an additive to
enhance rheological, mechanical or optical properties. For example,
a coupling agent may be blended with the latex material in order to
promote adhesion with the functionalized layered structure. A
cosmetic dye or photochromic dye or a color dye may be blended with
the latex material. Two or more compatible additives may be
employed.
[0040] In step 16a, the latex adhesive is applied in a liquid form
to the facing surface of the functionalized layered structure. The
latex adhesive is then dried in step 16b to form a uniformly thin,
solid layer of optical quality. The latex adhesive may be deposited
by various application methods known within the optics industry to
provide thin even coating layers, for example, spin coating or dip
coating. The wet latex layer is subjected to a drying step 16b,
which may include the introduction of heat. Drying may take place
within a controlled atmosphere involving clean, dry air.
[0041] Step 18 encompasses an HMA application step to deposit an
HMA material onto the dried latex layer. In step 18a, the HMA
material is applied in a liquid form to the facing surface of the
functionalized layered structure, on top of the latex layer. The
HMA material is then dried 18b to form a uniformly thin, solid
layer of optical quality. The HMA material may be deposited by
various application methods known within the optics industry to
provide thin even coating layers, for example, spin coating or dip
coating. The wet HMA layer is subjected to a drying step 18b, which
may include the introduction of heat. Drying may take place within
a controlled atmosphere involving clean, dry air.
[0042] The dried bi-adhesive layer is then placed in contact with
the facing surface of the optical base element, and subjected to a
lamination step 20. Generally, lamination involves a combination of
pressure and heat applied over a short period of time. It may also
include exposing the hot pressed ensemble to UV radiation, to cure
a UV curable adhesive, if present. Various systems and processes
are known within the optics industry to provide a precise and
uniform amount of pressure across optical surfaces. An exemplary
listing of lamination systems that may be employed with the
embodiments described herein include the following. So-called "hot
press" or "hot-air" systems may be used for lamination. An
accumulator device having a lens support may be set-up to apply
pressure, with the set-up then placed into an oven. An FST (Front
Side Transfer) process may be used, as described in EP 1917136. A
BST (Back Side Transfer) process may be used, as described in WO
2003/004255. Other HMC film lamination systems may be used. A
process, as described in WO 2006/105999, may be used with the
addition of heat. Injection molded lenses can be laminated in-mold,
by placing the functionalized layered structure into an open mold
opposite of where the lens is retained, and then closing the mold
in order to apply heat and pressure. We define Post Injection Press
Coating (PIPC) (as described in WO 2007/085910) as an in-mold
lamination system utilizing heat and pressure from an injection
mold to laminate a film onto a just molded lens. A basic laminating
process would involve applying pressure greater than 10 psi,
heating to at least 80 degrees C., and holding for at least about 2
to 5 minutes. Any one of these parameters could be adjusted higher
or lower depending on the overall process conditions and the total
amount of energy being introduced into the lamination.
[0043] The resulting functionalized optical element has good
mechanical properties as gauged by the high adhesive strength of
the functionalized layered support to the optical base element.
Samples of the resulting functionalized optical element are able to
withstand conventional lens processing and demanding adhesion tests
without delaminating. To conduct such adhesion tests, known as the
peel test, a 25.4 mm wide band was cut in the laminated film. The
lens was solidly attached to a platform. A force was applied at 90
degrees to peel the band of film from the lens. The peeling speed
was 2.54 mm/min. The force required to maintain the peeling speed
is recorded. The resulting functionalized optical element had good
optical properties due to the selection of adhesives and their
precise application methods. Several examples of the inventive
method are presented below along with comparative examples which
demonstrate their utility.
[0044] Examples 1 and 2. Adhesion comparison test on TAC/PVA/TAC
film between a urethane latex based on W-234 from Baxenden and
HMA-U42: TAC films were corona treated firstly, then the films were
spin coated with either the urethane latex solution or HMA-U42 in
the spin conditions of 450-500 rpm for 3-5 seconds and 1000-1500
rpm for 8-10 seconds and then dried at 60 degrees C. for 10-30 min.
After drying and cooling, the adhesion behavior on TAC film was
measured by classic crosshatch tape method as shown in the
following table. The results in the TABLE show that the latex had a
better adhesion score than the HMA on a TAC film.
TABLE-US-00001 TABLE Adhesive test on TAC polarized film Treat-
Crosshatch Tape Example Adhesives Film ment Coating adhesion score
Ex. 1 Latex TAC Corona Spin and dry 0 Ex. 2 HMA/U42 TAC Corona Spin
and dry 5
[0045] In the TABLE, crosshatch tape score 0 means perfect adhesion
between Latex adhesives and TAC film and 5 means adhesion failure
between HMA/U42 adhesives and TAC film.
[0046] Example 3. A TAC polarized film (TAC/PVA/TAC) was first
thermoformed to a curve close to the front side of a polycarbonate
lens. The convex side of the TAC film was subjected to a corona
discharge using Tantec equipment. A urethane latex adhesive, based
on W-234 from Baxenden, was spin coated onto the treated film
surface, and set to dry for 30 minutes at 60 degrees C. Next, an
HMA solution of Dispercoll.RTM. U 42 was spin coated on top of the
dried latex layer, and set to dry for 10 minutes at 60 degrees C.
The dried bi-adhesive layer was then set against a polycarbonate
lens, utilizing an accumulator device having a lens support and an
inflatable silicon membrane. The pressure was slowly increased to
30 psi to achieve full contact across the entire surfaces of the
film and lens. The accumulator set-up was place in an oven at 80
degrees C. for 30 minutes.
[0047] After lamination the polarized optical element exhibited
very strong adhesion between the film and the lens. No delamination
occurred even after severe Rx surfacing, polishing and edging. The
adhesion force between the laminated film and the lens was measured
by Instron equipment, wherein the 90 degree pull test resulted in a
1.01 N/mm measurement with a pull speed of 2.45 mm/minutes. In the
peel test, a force of 22.5 N was recorded to peel the film at 2.54
mm/min.
[0048] Comparative Example A. Example 3 was repeated except the TAC
film was only coated with a single layer of latex adhesive. The
resulting functionalized optical element displayed poor adhesion
between the film and the lens. The film could be easily peeled off
from the lens by hand. The adhesion was too low to be recorded by
the peel test.
[0049] Comparative Example B. Example 3 was repeated except the TAC
film was only coated with a single layer of HMA of U42. The
resulting functionalized optical element was measured as having
only 0.51 N/mm adhesion force between the film and the lens, which
is 50% of the adhesion force demonstrated in Example 3 with the
bi-adhesive layer. In the peel test a force of 11.5 N was recorded
to peel the film at 2.54 mm/min. Again, this correlates to 50% of
the adhesion force demonstrated in Example 3. These low adhesion
values are comparable to those obtained with PSA, for example, as
described in WO 2007/096521.
[0050] Example 4. Example 3 was repeated except the lamination step
was conducted by using a small hot press device with a pressure of
26 psi and heating at 90 degrees C. for 5 minutes. The resulting
functionalized optical element had the same good adhesion between
the functionalized layered structure and the optical base element.
In the peel test a force of 20 N was recorded to peel the film at
2.54 mm/min.
[0051] Example 5. Example 4 was repeated except the lamination step
was conducted by an in-mold lamination process (PIPC) right after a
lens was injection molded. The mold was opened, with the lens being
retained on one side. The polarized film was loaded into the other
side, against the empty molding insert. The mold was re-clamped at
considerable pressure whereby the residual mold heat allowed
lamination to be completed within 1 to 2 minutes. In this in-mold
lamination process, the molding pressure was about 7 tons and the
temperature was set at about 140 degrees C. The resulting
functionalized optical element had the same good adhesion between
the functionalized layered structure and the optical base element.
In the peel test a force of 65 N was recorded to peel the film at
2.54 mm/min. The increase is attributed to a more intimate bonding
resulting from the very higher temperature and pressure of the
injection mold.
[0052] Example 6. Example 4 was repeated except the polar TAC film
was replaced by a clear optical glade PET film and the lens was an
Essilor high index polyurethane lens material (Thin & Light
1.6). The obtained lens had very good adhesion between the
polyurethane lens and the PET film and the adhesion peel force was
about 31 N at 2.54 mm/min speed. The lens did not show any
de-lamination between the film and lens during edging and polish
processes.
[0053] Example 7. A bi-layer adhesive (a urethane latex based on
W-234 from Baxenden and Dispercoll.RTM. KA-8758) was also used to
adhere a top coat, and AR and HC coating layers onto the backside
of the lens materials. Firstly, the top coat and AR and HC coating
layers were reversely coated on a polycarbonate carrier (7.0 base
curve) which is described in the U.S. Pat. No. 6,562,466. Then a
bi-layer adhesive was coated as described in Example 1. After that,
the coated carrier was laminated onto a -2.00 Orma lens with the
back curve of 6.5 under lamination conditions of 30 psi balloon
pressure and 80 degrees C. for 4 minutes. After cool down, the
carrier was removed to get a top/AR and HC coating layer
transferred to the backside of the Orma lens. The adhesion between
coating layers and the lens was very good with an adhesion score of
0 according to the Essilor standard crosshatch tape test.
[0054] Comparative Example C. Example 7 was repeated except that no
latex adhesive layer was used between the HMC and Top/AR/HC layer.
The obtained lens showed that a good coating layer transferred but
did not have a good adhesion score (score 5) according to the
Essilor standard crosshatch tape test, which is considered a
coating adhesion failure.
[0055] Comparative Example D. Example 7 was repeated except that no
HMA adhesive layer was used. The obtained lens did not show a good
coating transfer and the adhesion score was 5 according to the
Essilor standard crosshatch tape test, which is considered a
coating adhesion failure.
[0056] Example 8. Example 7 was repeated except the pure KA-8758
HMA solution was replaced by a colloid contained in the KA-8758
HMA, which was made by a mixture of KA-8758 HMA solution (93 wt. %)
and the LUDOX.RTM. SM-30 colloidal silica, 30 wt. % suspension in
water (7 wt. %). The obtained lens had the same good adhesion
between the lens substrate and the AR and HC layer as found in
Example 7. It also had very good transparency. The most interesting
result by adding the silica colloid was that the hardness of the
HMA had been improved so that the surface of the lens was much
harder compared with Example 7. Therefore, the lens would not be
easily scratched by a finger nail.
[0057] The preceding description and examples have proposed
adhesive materials and methods for manufacturing functionally
enhanced optical articles. Various types of films and coatings have
been discussed which can be readily laminated onto optical base
elements. The embodiments described herein are useful in laminating
sandwiched polarizing films onto ophthalmic lenses. The films and
coatings are generally referred to as functionalized layered
structures, which may undergo pre-treatment steps prior to adhesive
application. The adhesive comprises a bi-layer adhesive structure
that includes two different types of adhesive. A latex adhesive
layer is disposed on the surface of the functionalized layered
structure, and a HMA is disposed between the latex adhesive layer
and the optical base element. The adhesive layers comprise a dry,
solid layer of uniform thinness throughout to provide optical
quality. Various dyes or other additive may be included in the
adhesive formulations.
[0058] In one embodiment of the method, the functionalized layered
support may be subject to corona discharge surface treatment and/or
thermoforming. The adhesive layers are individually coated on to
the functionalized layered support and allowed to dry, thereby
forming a uniformly thin bi-layer adhesive lamina of optical
quality. Spin-coating is advantageously employed as a coating
technique. Various hot press techniques for optical applications
may be used to deliver heat and pressure over a short period of
time to laminate the functionalized layered structure to the
optical base element to form a functionalized optical element with
high adhesive strength.
[0059] Having described preferred embodiments for lens
manufacturing, materials used therein for adhesives and films and
methods for processing same (which are intended to be illustrative
and not limiting), it is noted that modifications and variations
can be made by persons skilled in the art in light of the above
teachings. It is therefore to be understood that changes may be
made in the particular embodiments described herein as disclosed
which are within the scope and spirit of the invention as outlined
by the appended claims. Having thus described the embodiments with
the details and particularity required by the patent laws, what is
claimed and desired protected by Letters Patent is set forth in the
appended claims.
* * * * *