U.S. patent application number 12/160587 was filed with the patent office on 2011-03-10 for optical article comprising a double-layer abrasion and scratch resistant coating and method for production thereof.
This patent application is currently assigned to Essilor International (Compagnie Generale d'Otique. Invention is credited to Fabien Berit-Debat, Christian Bovet, Jean-Paul Cano, Amelie Kudla, Yves Leclaire.
Application Number | 20110058142 12/160587 |
Document ID | / |
Family ID | 38268898 |
Filed Date | 2011-03-10 |
United States Patent
Application |
20110058142 |
Kind Code |
A1 |
Berit-Debat; Fabien ; et
al. |
March 10, 2011 |
Optical Article Comprising a Double-Layer Abrasion and Scratch
Resistant Coating and Method for Production Thereof
Abstract
The invention relates to an optical article comprising a
substrate coated with an abrasion- and scratch-resistant coating
composed of a lower layer and an upper layer that do adhere to each
other, the upper layer and the lower layer being layers of cured
upper and lower layer compositions, said upper layer composition
comprising at least one organosilane, or a hydrolyzate thereof, of
formula R.sub.nY.sub.mSi(X).sub.4-n-m and at least one compound, or
a hydrolyzate thereof, of formula M(Z).sub.x, the following ratio
being lower than 2.3: Rs = theoretical dry matter weight of
compounds I in the upper layer composition theoretical dry matter
weight of compounds I I in the upper layer composition ##EQU00001##
said lower layer composition comprising at least one organosilane,
or a hydrolyzate thereof, of formula
R'.sub.n'Y'.sub.m'Si(X').sub.4-n'-m' and, optionally, at least one
compound, or a hydrolyzate thereof, of formula M'(Z').sub.y, the
following ratio being higher than 2.3: Ri = theoretical dry matter
weight of compounds III in the lower layer composition theoretical
dry matter extract of compounds I V in the lower layer composition
##EQU00002## In the hereabove formulas, M and M' are metals or
metalloids of valences x and y, at least equal to 4, R and R'
groups are monovalent organic groups that are bound to silicon
through a carbon atom and that contain at least one epoxy function,
X, X', Z and Z' groups are hydrolyzable groups, Y and Y' are
monovalent organic groups that are bound to silicon through a
carbon atom, n, m, n' and m' being integers such that n and n'=1 or
2 with n+m and n'+m'=1 or 2.
Inventors: |
Berit-Debat; Fabien;
(Charenton Le Pont, FR) ; Bovet; Christian;
(Charenton Le Pont, FR) ; Cano; Jean-Paul;
(Charenton Le Pont, FR) ; Kudla; Amelie;
(Charenton Le Pont, FR) ; Leclaire; Yves;
(Charenton Le Pont, FR) |
Assignee: |
Essilor International (Compagnie
Generale d'Otique
Charenton Le Pont
FR
|
Family ID: |
38268898 |
Appl. No.: |
12/160587 |
Filed: |
November 22, 2007 |
PCT Filed: |
November 22, 2007 |
PCT NO: |
PCT/FR2007/052383 |
371 Date: |
April 14, 2010 |
Current U.S.
Class: |
351/159.57 ;
427/164; 428/213; 428/336; 428/413 |
Current CPC
Class: |
C09D 183/04 20130101;
Y10T 428/265 20150115; G02B 1/14 20150115; G02C 7/02 20130101; Y10T
428/2495 20150115; G02B 1/105 20130101; Y10T 428/31511 20150401;
B05D 7/546 20130101; B05D 3/0254 20130101 |
Class at
Publication: |
351/166 ;
428/413; 428/336; 428/213; 427/164 |
International
Class: |
G02B 1/10 20060101
G02B001/10; B32B 27/38 20060101 B32B027/38; B32B 7/02 20060101
B32B007/02; B05D 5/06 20060101 B05D005/06; G02C 7/02 20060101
G02C007/02 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 23, 2006 |
FR |
0655085 |
Claims
1. An optical article comprising a substrate having at least one
main surface coated with an abrasion- and scratch-resistant
coating, said coating being composed, starting from the substrate,
of a lower layer and an upper layer that do adhere with each other,
the upper layer being a layer of a cured upper layer composition
and the lower layer being a layer of a cured lower layer
composition, wherein said upper layer composition comprises: at
least one organosilane compound, or a hydrolyzate thereof, of
formula: R.sub.nY.sub.mSi(X).sub.4-n-m (I) in which the R groups,
being the same or different, are monovalent organic groups that are
bound to silicon through a carbon atom and that contain at least
one epoxy function, the X groups, being the same or different, are
hydrolyzable groups, Y is a monovalent organic group bound to
silicon through a carbon atom, n and m being integers such that n=1
or 2 with n+m=1 or 2, and at least one compound, or a hydrolyzate
thereof, of formula: M(Z).sub.x (II) in which M represents a metal
or a metalloid, the Z groups, being the same or different, are
hydrolyzable groups and x, equal to or higher than 4, preferably
from 4 to 6, is the metal or metalloid M valence, the ratio: Rs =
theoretical dry matter weight of compounds I in the upper layer
composition theoretical dry matter weight of compounds I I in the
upper layer composition ##EQU00008## being lower than or equal to
2.3, and wherein said lower layer composition comprises: at least
one organosilane compound, or a hydrolyzate thereof, of formula:
R'.sub.n'Y'.sub.m'Si(X').sub.4-n'-m' (III) in which the R' groups,
being the same or different, are monovalent organic groups that are
bound to silicon through a carbon atom and that contain at least
one epoxy function, the X' groups, being the same or different, are
hydrolyzable groups, Y' is a monovalent organic group bound to
silicon through a carbon atom, n' and m' being integers such that
n'=1 or 2 with n'+m'=1 or 2, and optionally, at least one compound,
or a hydrolyzate thereof, of formula: M'(Z').sub.y (IV) in which M'
represents a metal or a metalloid, the Z' groups, being the same or
different, are hydrolyzable groups and y, equal to or higher than
4, preferably from 4 to 6, is the metal or metalloid M' valence,
the ratio: Ri = theoretical dry matter weight of compounds III in
the lower layer composition theoretical dry matter weight of
compounds I V in the lower layer composition ##EQU00009## being
higher than 2.3.
2. An article according to claim 1, wherein compound (II) is of
formula Si(Z).sub.4, in which the Z groups, being the same or
different, are hydrolyzable groups, and/or wherein compound (IV) is
of formula Si(Z').sub.4, in which the Z' groups, being the same or
different, are hydrolyzable groups.
3. An article according to claim 1 or 2, wherein R.sup.5 is lower
than or equal to 2.0, preferably lower than or equal to 1.5, more
preferably lower than or equal to 1.25, and even more preferably
lower than or equal to 1.1, and higher than or equal to 0.85, more
preferably higher than or equal to 0.9, even more preferably higher
than or equal to 0.95.
4. An article according to claim 1, 2 or 3, wherein R.sup.1 is
higher than or equal to 3.0, preferably higher than or equal to
3.5, more preferably higher than or equal to 4.5, even more
preferably higher than or equal to 10.
5. An article according to any preceding claim, wherein the
theoretical dry matter weight of compounds I represents from 30 to
60% of the upper layer composition dry matter weight, more
preferably from 40 to 55%.
6. An article according to any preceding claim, wherein the
theoretical dry matter weight of compounds III represents more than
40% of the lower layer composition dry matter weight, more
preferably more than 50%, even more preferably more than 60% and
most preferably more than 65%.
7. An article according to any preceding claim, wherein the
theoretical dry matter weight of compounds IV represents less than
30% of the lower layer composition dry matter weight, more
preferably less than 25%, even more preferably less than 20% and
most preferably less than 10%.
8. An article according to any preceding claim, wherein the
thickness of the abrasion- and scratch-resistant coating does vary
from 1 to 15 .mu.m, preferably from 1 to 10 .mu.m, more preferably
from 2 to 8 .mu.m, and even more preferably from 3 to 6 .mu.m.
9. An article according to any preceding claim, wherein the
thickness ratio of the lower layer to the upper layer is higher
than or equal to 1.5, more preferably higher than or equal to 2.0,
and even more preferably higher than or equal to 3.0.
10. An article according to any preceding claim, wherein the X, X',
Z, Z' hydrolyzable groups are selected, independently from each
other, from --O--R.sup.1 alkoxy groups, wherein R.sup.1 is a linear
or branched, alkyl group, preferably a C.sub.1-C.sub.4 alkyl group,
or an alkoxyalkyl group, --O--C(O)R.sup.3 acyloxy groups, wherein
R.sup.3 is an alkyl group, preferably a C.sub.1-C.sub.6 alkyl
group, preferably a methyl or an ethyl group, halogens such as Cl
and Br and amino groups optionally substituted by one or two alkyl
or silane group(s).
11. An article according to any preceding claim, wherein the Y or
Y' groups are selected, independently from each other, from
C.sub.1-C.sub.4 alkyl groups, alkenyl, C.sub.6-C.sub.10 aryl
groups, methacryloxyalkyl, acryloxyalkyl, fluoroalkyl,
perfluoroalkyl, (poly)fluoro alkoxy[(poly)alkylenoxy]alkyl and
perfluoro alkoxy[(poly)alkylenoxy]alkyl groups.
12. An article according to any preceding claim, wherein the R or
R' groups are selected, independently from each other, from groups
of formulas V and VI: ##STR00003## in which R.sup.2 is an alkyl
group, preferably a methyl group, or a hydrogen atom, a and c are
integers ranging from 1 to 6, and b is 0, 1 or 2.
13. An article according to claim 12, wherein the R or R' groups
are selected, independently from each other, from
.gamma.-glycidoxypropyl groups, .beta.-(3,4-epoxycyclohexyl)ethyl
and .gamma.-glycidoxyethoxypropyl groups, and preferably represent
the .gamma.-glycidoxypropyl group.
14. An article according to any preceding claim, wherein compounds
of formula I and/or III are selected, independently from each
other, from compounds of formulas VII and VIII: ##STR00004## in
which R.sup.1 is an alkyl moiety having from 1 to 6 carbon atoms,
preferably a methyl or an ethyl moiety, a and c are integers
ranging from 1 to 6, and b is 0, 1 or 2.
15. An article according to any preceding claim, wherein compounds
of formula II and/or IV are selected, independently from each
other, from tetraalkoxysilanes, preferably from tetrathoxysilane,
tetramethoxysilane, tetra(n-propoxy)silane, tetra(1-propoxy)silane,
tetra(n-butoxy)silane, tetra(sec-butoxy)silane and
tetra(t-butoxy)silane.
16. An article according to any preceding claim, wherein the lower
and/or upper layer compositions comprise at least one condensation
catalyst and/or at least one curing catalyst.
17. An article according to claim 0, wherein the condensation
catalyst is selected from acids or anhydrides of polyfunctional
saturated or unsaturated acids, preferably from maleic acid,
itaconic acid, trimellitic acid and trimellitic anhydride.
18. An article according to claim 0 or 0, wherein the curing
catalyst is selected from imidazole derivatives and their
imidazolium salts, N-cyanoguanidine, acetylacetone metallic salts
of formula M(CH.sub.3COCHCOCH.sub.3).sub.n, wherein M is a metallic
ion, preferably Zn.sup.2+, Co.sup.3+, Fe.sup.3+ or Cr.sup.3+, and n
is an integer ranging from 1 to 3, ammonium tetrathiocyanatodiamine
chromate(III), aluminium-based compounds, metal-based carboxylates
such as zinc, titanium, zirconium, tin or magnesium, preferably
zinc octoate or stannous octoate, iodonium salts and sulfonium
salts.
19. An article according to claim 0, wherein the aluminium-based
compound is selected from aluminium chelates, aluminium(III)
acylates and alcoholates, preferably from aluminium
acetylacetonate, aluminium ethylmono(acetoacetate)
bisacetylacetonate, aluminium monoacetyl acetonate ethyl
bis(acetoacetate), di-n-butoxy aluminium ethyl mono(acetoacetate)
and di-i-propoxy aluminium ethylmono(acetoacetate).
20. An article according to any of claims 1 to 0, wherein the lower
and/or upper layer compositions comprise a catalytic system
composed of aluminium acetylacetonate or composed of a mixture of
itaconic acid and N-cyanoguanidine.
21. An article according to any preceding claim, wherein the lower
and/or upper layer compositions comprise less than 10% by weight of
fillers as related to the total weight of the composition, more
preferably are free from any filler.
22. An article according to any preceding claim, wherein it
comprises, starting from the substrate, an impact-resistant primer
layer coated with said abrasion- and scratch-resistant coating,
said primer layer preferably comprising colloidal fillers.
23. An article according to any preceding claim, wherein it
comprises a supplementary layer of an abrasion-resistant and/or
scratch-resistant coating contacting said upper layer, said
abrasion-resistant and/or scratch-resistant supplementary layer
being a layer of cured supplementary abrasion-resistant and/or
scratch-resistant layer composition, said supplementary layer
composition comprising: at least one organosilane compound, or a
hydrolyzate thereof, of formula:
R''.sub.n''Y''.sub.m''Si(X'').sub.4-n''-m'' (IX) in which the R''
groups, being the same or different, are monovalent organic groups
that are bound to silicon through a carbon atom and that contain at
least one epoxy function, the X'' groups, being the same or
different, are hydrolyzable groups, Y'' is a monovalent organic
group bound to silicon through a carbon atom, n'' and m'' being
integers such that n''=1 or 2 with n''+m''=1 or 2, and at least one
compound, or a hydrolyzate thereof, of formula: M''(Z'').sub.z (X)
in which M'' represents a metal or a metalloid, the Z'' groups,
being the same or different, are hydrolyzable groups and z, equal
to or higher than 4, preferably from 4 to 6, is the metal or
metalloid M'' valence, the ratio: Rss = theoretical dry matter
weight of compounds IX in the supplementary layer composition
theoretical dry matter weight of compounds X in the supplementary
layer composition ##EQU00010## being lower than or equal to 2.3 and
strictly lower than ratio Rs, the supplementary theoretical dry
matter weight of compounds X representing at least 45% of the dry
matter weight of the supplementary abrasion-resistant and/or
scratch-resistant layer composition and the thickness of the
supplementary abrasion-resistant and/or scratch-resistant layer
being lower than that of said upper layer.
24. An article according to claim 22, wherein Rss is lower than or
equal to 2.0, more preferably lower than or equal to 1.5, even more
preferably lower than or equal to 1.25, and most preferably lower
than or equal to 1.1.
25. An article according to claim 23, wherein Rss is higher than or
equal to 0.85, more preferably higher than or equal to 0.9, even
more preferably higher than or equal to 0.95.
26. An article according to any preceding claim, wherein an
antireflective coating is deposited onto the abrasion- and
scratch-resistant coating.
27. An article according to any preceding claim, further defined as
being an optical lens, preferably an ophthalmic lens.
28. A method for making an abrasion- and scratch-resistant optical
article comprising a substrate, comprising: a) providing an optical
article comprising a substrate having at least one main surface; b)
depositing onto a substrate main surface a layer of a lower layer
composition such as defined in any of claims 1 to 0; c) at least
partially curing said lower layer composition using a thermal
process; d) depositing onto the layer resulting from the previous
step a layer of an upper layer composition such as defined in any
of claims 1 to 0; e) curing said upper layer composition using a
thermal process; f) recovering an optical article comprising a
substrate having a main surface coated with an abrasion- and
scratch-resistant coating composed of a lower layer adhering to an
upper layer.
29. A method according to claim 27, wherein the lower layer
composition is totally cured using a thermal process during step c)
at a temperature ranging from 80 to 150.degree. C., for 30 minutes
to 4 hours.
30. A method according to claim 27 or 28, wherein the surface of
the article resulting from step c) does undergo before step d) a
surface preparation treatment intended to increase the adhesion of
the upper layer.
31. A method according to claim 29, wherein the surface preparation
treatment is selected from a bombardment with energetic species,
preferably an ion beam or an electron beam, a corona discharge
treatment, an ion spallation, an ultraviolet treatment, a plasma
treatment under vacuum, an acidic or a basic treatment and/or a
treatment with solvents, or any combination of these treatments,
preferably a basic solution treatment.
32. The method of claim 27, wherein the lower layer composition is
partially cured using a thermal process during step c) at a
temperature ranging from 70 to 120.degree. C., preferably from 80
to 120.degree. C., for 1 to 30 minutes, more preferably for 3 to 20
minutes and even more preferably for 5 to 10 minutes and wherein
the surface of the article resulting from step c) does not undergo
before step d) any surface preparation treatment.
Description
[0001] The present invention relates to an optical article, such as
an ophthalmic lens in organic glass, coated with a bilayered
coating based in particular on thermosetting polysiloxane
compositions which do provide it simultaneously with performances
in both abrasion and scratch resistance, closed to those of mineral
glass, as well as a method for making such an optical article.
[0002] Ophthalmic lenses made of a transparent, organic material,
or organic glass, lighter than mineral glass, are nowadays broadly
used. However, organic glasses as a drawback suffer from being more
sensitive to scratch and abrasion as compared to traditional
mineral glasses.
[0003] It is usual to coat any ophthalmic lens with various
coatings, so as to provide this lens with improved mechanical
and/or optical properties. Thus, traditionally, coatings are
successively deposited onto an ophthalmic lens, such as
impact-resistant coatings, abrasion-resistant coatings and/or
scratch-resistant and antireflective coatings.
[0004] Abrasion-resistant and/or scratch-resistant coatings used to
protect the surface of organic glasses are typically hard
monolayered coatings of the poly(meth)acrylic type or based on
silane hydrolyzates.
[0005] A known method for making abrasion-resistant coatings
consists in polymerizing alkoxysilanes in the presence of curing
catalysts such as aluminium derivatives. As an illustration of some
literature covering such a technique, the U.S. Pat. No. 4,211,823
may be mentioned, that describes compositions comprising a
hydrolyzate of a silane having an epoxy moiety and at least two
alkoxy moieties directly bound to the silicon atom, silica fine
particles, some aluminium chelates, in a solvent medium comprising
more than 1% by weight of water, said compositions being used for
coating substrates in a plastic material.
[0006] The U.S. Pat. No. 5,916,669 describes a bilayered coating
which poly(urethane-acrylate) type upper layer is a hard layer,
more vulnerable than the lower layer, which is a more flexible
layer of acrylate nature. The upper layer is a layer providing a
protection against scratching, whereas the lower layer makes it
possible to increase the upper layer abrasion resistance without
impairing its scratch resistance properties. The patent does
mention that combining these two layers makes it possible to obtain
simultaneously good abrasion and scratch resistances.
[0007] The U.S. Pat. No. 5,254,395 and U.S. Pat. No. 5,114,783 also
describe bilayered abrasion-resistant and scratch-resistant
coatings, comprising a hard, highly cross-linked acrylic
copolymer-based upper layer, bonded to a flexible lower layer
formed from a mixture consisting in a cross-linked, aliphatic
urethane and acrylate copolymer and in a small amount of a
multifunctional acrylic monomer.
[0008] The U.S. Pat. No. 6,808,812 describes a composition for an
abrasion-resistant or scratch-resistant coating, comprising the
reaction product of oxalic acid with an organometallic derivative,
preferably a titanate such as tetra-isopropoxytitanium, an
epoxyalkoxysilane such as .gamma.-glycidoxypropyl trimethoxysilane
(GLYMO) and optionally a second alkoxysilane such as dimethyl
diethoxysilane (DMDES).
[0009] According to an embodiment described in this patent, this
composition may be deposited onto a substrate already coated with
an abrasion-resistant coating of (meth)acrylic or polysiloxane
nature, for example based on an epoxyalkoxysilane and colloidal
silica hydrolyzate. Such a bilayered coating offers an excellent
combination of abrasion and scratch resistance properties.
[0010] The French patent FR 2721720 discloses a bilayered coating
comprising an upper layer consisting in an impact-resistant primer
of the polysiloxane type (methyl-GLYMO or GLYMO) and an
abrasion-resistant lower layer also of the polysiloxane type,
comprising a methyl-GLYMO (.gamma.-glycidoxypropylmethyl
dimethoxysilane) matrix wherein colloidal silica is dispersed.
[0011] There is a need to improve the scratch-resistance properties
of such coatings.
[0012] It is therefore an object of the present invention to
provide a transparent optical article, particularly an ophthalmic
lens, comprising a substrate in mineral or organic glass and a
coating providing it with significantly improved scratch resistance
and abrasion resistance properties, wherein obtaining either one of
both properties should not be detrimental to the other, and this
even when said coating is combined with an antireflective
coating.
[0013] It is also an object of the present invention to provide a
scratch-resistant and abrasion-resistant coating such as hereabove,
that does not make vulnerable the substrate onto which it is
deposited. The scratch-resistant and abrasion-resistant coating
must have the transparency required for being applicable to the
optics field, as well as a good adhesion to the substrates,
particularly those made of an organic material. Moreover, the
layers forming it must possess a good adhesion to each other.
[0014] It is a further object of the present invention to provide a
method for making such optical articles, which may be easily
integrated into the usual production process for optical
articles.
[0015] The hereabove determined objectives are aimed at according
to the invention by an optical article comprising a substrate
having at least one main surface coated with an abrasion- and
scratch-resistant coating, said coating being composed, starting
from the substrate, of a lower layer and an upper layer that do
adhere with each other, the upper layer being a layer of a cured
upper layer composition and the lower layer being a layer of a
cured lower layer composition, said upper layer composition
comprising: [0016] at least one organosilane compound, or a
hydrolyzate thereof, of formula:
[0016] R.sub.nY.sub.mSi(X).sub.4-n-m (I)
[0017] wherein the R groups, being the same or different, are
monovalent organic groups that are bound to silicon through a
carbon atom and that contain at least one epoxy function, the X
groups, being the same or different, are hydrolyzable groups, Y is
a monovalent organic group bound to silicon through a carbon atom,
n and m being integers such that n=1 or 2 with n+m=1 or 2, and
[0018] at least one compound, or a hydrolyzate thereof, of
formula:
[0018] M(Z).sub.x (II)
[0019] wherein M represents a metal or a metalloid, the Z groups,
being the same or different, are hydrolyzable groups and x, equal
to or higher than 4, is the metal or metalloid M valence, the
ratio:
Rs = theoretical dry matter weight of compounds I in the upper
layer composition theoretical dry matter weight of compounds I I in
the upper layer composition ##EQU00003##
[0020] being lower than or equal to 2.3, and said lower layer
composition comprising: [0021] at least one organosilane compound,
or a hydrolyzate thereof, of formula:
[0021] R'.sub.n'Y'.sub.m'Si(X').sub.4-n'-m' (III)
[0022] wherein the R' groups, being the same or different, are
monovalent organic groups that are bound to silicon through a
carbon atom and that contain at least one epoxy function, the X'
groups, being the same or different, are hydrolyzable groups, Y' is
a monovalent organic group bound to silicon through a carbon atom,
n' and m' being integers such that n'=1 or 2 with n'+m'=1 or 2, and
[0023] optionally, at least one compound, or a hydrolyzate thereof,
of formula:
[0023] M'(Z').sub.y (IV)
[0024] wherein M' represents a metal or a metalloid, the Z' groups,
being the same or different, are hydrolyzable groups and y, equal
to or higher than 4, is the metal or metalloid M' valence, the
ratio:
Ri = theoretical dry matter weight of compounds III in the lower
layer composition theoretical dry matter weight of compounds I V in
the lower layer composition ##EQU00004##
[0025] being higher than 2.3.
[0026] In the present application, when an optical article
comprises one or more coating(s) on its surface, "depositing a
layer or a coating onto the article" means that a layer or a
coating has been deposited on the exposed surface of the article
external coating, that is to say on its coating that is the most
distant from the substrate.
[0027] A coating that is "on" a substrate or that has been
deposited "onto" a substrate is defined as being a coating (i) that
is positioned above the substrate, (ii) that is not necessarily in
contact with the substrate, which means that one or more
intermediate coating(s) may be arranged between the substrate and
the coating of interest, and (iii) that does not necessarily
totally cover the substrate.
[0028] The optical article of the invention comprises a substrate,
preferably a transparent substrate, in organic or mineral glass,
having front and rear main faces, at least one of said main faces
bearing a bilayered scratch-resistant and abrasion-resistant
coating, preferably both main faces. Throughout the following
application, the abrasion- and scratch-resistant coating of the
invention will typically be simply called "abrasion-resistant
coating" or "bilayered coating."
[0029] Generally speaking, the abrasion-resistant coating of the
optical article of the invention may be deposited onto any
substrate, and preferably organic glass substrates, for example a
thermoplastic or thermosetting plastic material.
[0030] Thermoplastic materials suitable for substrates encompass
(meth)acrylic (co)polymers, in particular methyl poly(methacrylate)
(PMMA), thio(meth)acrylic (co)polymers, polyvinyl butyral (PVB),
polycarbonates (PC), polyurethanes (PU), poly(thiourethanes),
polyol allylcarbonate (co)polymers, thermoplastic copolymers of
ethylene and vinyl acetate, polyesters such as polyethylene
terephthalate (PET) or polybutylene terephthalate (PBT),
polyepisulfides, polyepoxides, copolymers of polycarbonates and
polyesters, copolymers of cycloolefins such as copolymers of
ethylene and norbornene or ethylene and cyclopentadiene, and
combinations thereof.
[0031] As used herein, a "(co)polymer" means either a copolymer or
a polymer. A "(meth)acrylate" means either an acrylate or a
methacrylate.
[0032] According to the invention, preferred substrates may include
substrates obtained by polymerizing alkyl (metha)crylates, in
particular C.sub.1-C.sub.4 alkyl (meth)acrylates, such as methyl
(meth)acrylate and ethyl (meth)acrylate, aromatic polyethoxylated
(meth)acrylates such as polyethoxylated bisphenol
di(meth)acrylates, allyl derivatives such as allyl carbonates of
aliphatic or aromatic, linear or branched polyols,
thio(meth)acrylates, episulfides and polythiol and polyisocyanate
based precursor mixtures (for producing polythiourethans).
[0033] As used herein, a "polycarbonate" (PC) means equally
homopolycarbonates and copolycarbonates and block copolycarbonates.
Polycarbonates are commercially available and are marketed for
example by GENERAL ELECTRIC COMPANY under the trade name
LEXAN.RTM., by TEIJIN under the trade name PANLITE.RTM., by BAYER
under the trade name BAYBLEND.RTM., by MOBAY CHEMICHAL Corp. under
the trade name MAKROLON.RTM. and by DOW CHEMICAL Co. under the
trade name CALIBRE.RTM..
[0034] Suitable examples of (co)polymers of polyol allyl carbonates
encompass (co)polymers of ethylene glycol bis(allyl carbonate), of
diethylene glycol bis 2-methyl carbonate, of diethylene glycol
bis(allyl carbonate), of ethylene glycol bis(2-chloro allyl
carbonate), of triethylene glycol bis(allyl carbonate), of
1,3-propanediol bis(allyl carbonate), of propylene glycol
bis(2-ethyl allyl carbonate), of 1,3-butenediol bis(allyl
carbonate), of 1,4-butenediol bis(2-bromo allyl carbonate), of
dipropylene glycol bis(allyl carbonate), of trimethylene glycol
bis(2-ethyl allyl carbonate), of pentamethylene glycol bis(allyl
carbonate), of isopropylene bisphenol A bis(allyl carbonate).
[0035] Particularly recommended substrates are those substrates
obtained by (co)polymerizing diethylene glycol bis allyl carbonate
marketed, for example, under the trade name CR-39.RTM. by PPG
Industries (ORMA.RTM. lenses, by ESSILOR).
[0036] Particularly recommended substrates also encompass those
substrates obtained by polymerizing thio(meth)acrylic monomers,
such as those described in the French patent application FR
2734827.
[0037] Naturally, the substrates may be obtained by polymerizing
mixtures from the previously mentioned monomers, or they may also
comprise mixtures of these polymers and (co)polymers.
[0038] According to an embodiment of the invention, the substrate
comprises a front face and a rear face, and the abrasion-resistant
coating may be applied on at least one of said faces. It is
preferably applied on the front and rear faces of the
substrate.
[0039] As used herein, the "rear face" (typically concave) of the
substrate means the face which during the use of the article stands
the nearest to the wearer's eye. On the contrary, the "front face"
(typically convex) of the substrate means the face which during the
use of the article is the most distant from the wearer's eye.
[0040] Prior to depositing the abrasion-resistant coating onto the
substrate that has been optionally already coated, for example with
an impact-resistant primer layer, it is usual to expose the
optionally coated surface of said substrate to a treatment for
reinforcing the adhesion of the abrasion-resistant lower layer,
that is typically conducted under vacuum, such as a bombardment
with energetic species, for example with an ion beam ("Ion
Pre-Cleaning" or "IPC"), a corona discharge treatment, by ion
spallation or plasma treatment under vacuum. Thanks to these
cleaning treatments, the substrate surface cleanliness is
optimized. The ion bombardment treatment is preferred, using
preferably argon, oxygen or mixtures thereof as the ionizing gas,
under an accelerating voltage typically ranging from 50 to 200
V.
[0041] As used herein, "energetic species" means species which
energy ranges from 1 to 150 eV, preferably from 10 to 150 eV, and
more preferably from 40 to 150 eV. The energetic species may be
chemical species such as ions, radicals or species like photons or
electrons.
[0042] An acidic or a basic chemical surface pre-treatment may also
be conducted, or using a solvent or a mixture of solvents.
[0043] According to the present invention, the bilayered
scratch-resistant and abrasion-resistant coating may be deposited
directly onto a bare substrate. In some applications, it is
preferred the substrate main surface be coated with one or more
functional coating(s) prior to depositing the abrasion-resistant
coating of the invention. These functional coatings may be, without
limitation, an impact-resistant primer layer, a polarized coating,
a photochromic coating, an antistatic coating, an additional
abrasion-resistant and/or scratch-resistant coating or a coloured
coating.
[0044] The abrasion-resistant bilayered coating of the invention is
preferably deposited onto a bare substrate, onto a substrate coated
with an additional abrasion-resistant and/or scratch-resistant
coating which has preferably a single layer, or onto a substrate
coated with a primer layer improving the impact resistance and/or
the adhesion of the following layers in the final product.
[0045] Such coating may be any impact-resistant primer layer
traditionally used for articles made of a transparent polymer
material, such as ophthalmic lenses.
[0046] As preferred primer compositions, compositions may be
mentioned, that are based on thermoplastic polyurethanes, such as
those described in the Japanese patents JP 63-141001 and JP
63-87223, poly(meth)acrylic primer compositions, such as those
described in the U.S. Pat. No. 5,015,523, compositions based on
thermosetting polyurethanes, such as those described in the
European patent EP 0404111 and compositions based on
poly(meth)acrylic latex or polyurethane type latex, such as those
described in the U.S. Pat. No. 5,316,791 and EP 0680492.
[0047] Preferred primer compositions are those compositions based
on polyurethanes and those compositions based on latex, in
particular polyurethane type latex.
[0048] Poly(meth)acrylic latices are copolymer latices mainly
consisting in a (meth)acrylate, such as for example ethyl, butyl,
methoxyethyl or ethoxyethyl (meth)acrylate, with a typically minor
content of at least one other co-monomer, such as for example
styrene.
[0049] Preferred poly(meth)acrylic latices are copolymer latices of
acrylate and styrene. Such copolymer latices of acrylate and
styrene are commercially available from ZENECA RESINS under the
trade name NEOCRYL.RTM..
[0050] Polyurethane latices are also known and commercially
available. As an example, polyurethane latices containing polyester
units may be mentioned. Such latices are also marketed by ZENECA
RESINS under the trade name NEOREZ.RTM. and by BAXENDEN CHEMICALS
under the trade name WITCOBOND.RTM..
[0051] Commercial primer compositions to be suitably used in the
present invention include Witcobond.RTM. 232, Witcobond.RTM. 234,
Witcobond.RTM. 240, Witcobond.RTM. 242, Neorez.RTM. R-962,
Neorez.RTM. R-972, Neorez.RTM. R-986 and Neorez.RTM. R-9603
compositions.
[0052] Mixtures of such latices may also be used in the primer
compositions, in particular mixtures of polyurethane latex and
poly(meth)acrylic latex.
[0053] The primer composition preferably comprises fillers, that
are typically nanoparticles, so as to increase the hardness and/or
the refractive index of the cured coating, and also to prevent any
possible diffusion of the layer just deposited onto the primer.
Such nanoparticles may be organic or inorganic in nature. A mixture
of organic and inorganic nanoparticles may also be used.
[0054] Inorganic nanoparticles are preferably used, and in
particular nanoparticles of the metal oxide or metalloid, nitride
or fluoride type, or mixtures thereof.
[0055] Examples of nanoparticles that are suitably used in the
invention include nanoparticles of the following compounds:
SiO.sub.2, Al.sub.2O.sub.3, ZrO.sub.2, TiO.sub.2, Sb.sub.2O.sub.5,
Ta.sub.2O.sub.5, ZnO.sub.2, tin oxide, indium oxide, cerium oxide,
WO.sub.3, Y.sub.2O.sub.3, and mixtures thereof.
[0056] Fillers are preferably used in the colloidal form, that is
to say in the form of fine particles, which diameter (or the
longest side) is lower than 1 .mu.m, preferably lower than 150 nm,
more preferably lower than 100 nm, even more preferably comprised
from 10 to 80 nm, dispersed in a dispersing medium such as water,
an alcohol, a ketone, an ester or mixtures thereof, preferably an
alcohol.
[0057] Fillers are preferably high refractive index colloids (or
precursors thereof), that is to say colloids consisting in a
material which refractive index is higher than 1.55. Fillers may in
particular be TiO.sub.2, ZrO.sub.2, Sb.sub.2O.sub.5, SnO.sub.2,
WO.sub.3, Al.sub.2O.sub.3, Y.sub.2O.sub.3, Ta.sub.2O.sub.5 colloids
and mixtures thereof. The primer composition preferably comprises
from 5% to 65%, preferably from 5 to 50% by weight of fillers.
[0058] Fillers may also be composite particles, preferably
composite particle colloids, for example based on following oxides:
SiO.sub.2/TiO.sub.2, SiO.sub.2/ZrO.sub.2,
SiO.sub.2/TiO.sub.2/ZrO.sub.2,
TiO.sub.2/SiO.sub.2/ZrO.sub.2/SnO.sub.2. Such composite particle
colloids are available from the Catalysts and Chemical Company.
[0059] Particularly recommended composite particles are described
in the patents EP 730168, JP 11310755, JP 200204301 and JP
2002363442.
[0060] Such primer compositions may be deposited onto the article
faces by dip coating or by spin coating, then are dried at a
temperature of at least 70.degree. C. and up to 100.degree. C.,
preferably of about 90.degree. C., for a time period ranging from 2
minutes to 2 hours, typically of about 15 minutes, to form primer
layers which once cured are from 0.2 to 2.5 .mu.m, preferably from
0.5 to 1.5 .mu.m thick.
[0061] The optional abrasion-resistant and/or scratch-resistant
coating onto which the bilayered scratch-resistant and
abrasion-resistant coating of the invention may be deposited will
be typically called "additional abrasion-resistant and/or
scratch-resistant coating." This additional abrasion-resistant
and/or scratch-resistant coating is preferably a monolayered
coating.
[0062] It may be formed with any layer traditionally used as an
abrasion-resistant and/or scratch-resistant coating in the field of
ophthalmic lenses. It is preferably a hard coating based on
poly(meth)acrylates or silicones comprising typically one or more
mineral filler(s) that are intended to increase the hardness and/or
the refractive index of the coating once cured. Additional
abrasion-resistant and/or scratch-resistant hard coatings
recommended according to the present invention include for example
coatings obtained from compositions comprising at least one silane,
preferably one alkoxysilane and/or one hydrolyzate thereof,
obtained for example by hydrolyzing with a hydrochloric acid
solution and optionally with condensing and/or curing
catalysts.
[0063] The additional abrasion-resistant and/or scratch-resistant
coatings preferred in the present invention are coatings based on
epoxysilane hydrolyzates, in particular those described in the
French patent application FR 2702486 and in the U.S. Pat. No.
4,211,823 and U.S. Pat. No. 5,015,523, or coatings based on
poly(meth)acrylates such as those described in the international
application WO 2007/051841.
[0064] The additional abrasion-resistant and/or scratch-resistant
coating composition may be deposited onto the substrate main face
by dip coating or by spin coating. It is then cured using the
suitable mode (preferably a thermal mode, or using ultraviolet
radiation).
[0065] In the final optical article, the thickness of this
additional abrasion-resistant and/or scratch-resistant coating does
typically vary from 2 to 10 .mu.m, preferably from 2 to 5
.mu.m.
[0066] The abrasion- and scratch-resistant coating of the invention
does consist in two adjacent layers having different
characteristics and strongly adhering to each other. The
compositions for preparing these two layers, the composition of the
abrasion-resistant upper layer and the composition of the
abrasion-resistant lower layer are formulated so that said coating
has a hardness gradient, the upper layer being harder than the
lower layer.
[0067] As used herein, the "abrasion-resistant coating upper
layer", which will be simply called "upper layer," means the
abrasion-resistant coating layer that is the most distant from the
substrate.
[0068] As used herein, the abrasion-resistant coating lower layer,
which will be simply called "lower layer," means the
abrasion-resistant coating layer that is the nearest to the
substrate.
[0069] Both abrasion-resistant coating compositions of the
invention are thermosetting compositions which, after having been
applied onto a substrate main surface of the optical article, and
once cured, do result in a bilayered scratch-resistant and
abrasion-resistant coating, preferably of the polysiloxane
type.
[0070] The upper layer composition necessarily comprises a
cross-linking agent of formula II, whereas the presence of a
cross-linking agent of formula IV is only optional in the lower
layer composition. Its amount is intentionally limited so as to
obtain a lower layer that is more flexible as compared to the upper
layer which in turn does possess a higher hardness because of its
higher crosslinking rate.
[0071] In the present application, the characteristics and
preferences stated as regards compounds of formulas I to IV also
apply to their hydrolyzates.
[0072] Epoxysilane compounds of formulas I and III will be first
described simultaneously. Of course, the nature of compound I
present in the upper layer and that of compound III present in the
lower layer are independent from each other. This means, for
example, that the values for n and m integers are independent from
those of n' and m' integers.
[0073] Compounds of formulas I or III do comprise two or three X or
X' hydrolyzable groups directly bound to the silicon atom, each
leading to an OH group after hydrolysis, one or two monovalent
organic R or R' groups that are bound to silicon with a carbon atom
and that contain at least one epoxy function, and zero or one
organic monovalent Y or Y' group (m and m'.dbd.0 or 1). It should
be noted that Si--OH functions may initially be present in
compounds of formulas I or III, and if so, they are considered as
being hydrolyzates.
[0074] n et m integers such as defined hereabove do define three
classes of compounds I. Compounds of formula RYSi(X).sub.2,
compounds of formula R.sub.2Si(X).sub.2, and lastly compounds of
formula RSi(X).sub.3. Amongst them, epoxysilanes of formula
RSi(X).sub.3, which comprise three hydrolyzable groups bound to the
silicon atom, are preferred. The same conclusions apply to
compounds of formula III defined by n' and m' integers.
[0075] X or X' hydrolyzable groups may represent, independently
from each other and without limitation, --O--R.sup.1 alkoxy groups,
wherein R.sup.1 is preferably a linear or branched, alkyl group,
preferably a C.sub.1-C.sub.4 alkyl group, or an alkoxyalkyl group,
--O--C(O)R.sup.3 acyloxy groups, wherein R.sup.3 is an alkyl group,
preferably a C.sub.1-C.sub.6 alkyl group, preferably a methyl or an
ethyl group, halogens such as Cl and Br, amino groups optionally
substituted with one or two functional group(s) such as an alkyl or
a silane group, for example a --NHSiMe.sub.3 group.
[0076] Preferably, X or X' groups are alkoxy groups, and in
particular methoxy, ethoxy, propoxy or butoxy groups, more
preferably methoxy or ethoxy groups, thus making the compounds of
formulas I or III defined as epoxyalkoxysilanes.
[0077] Monovalent R or R' groups that are bound to silicon with a
carbon atom are organic groups as they do contain at least one
epoxy function, preferably only one epoxy function.
[0078] As used herein, an "epoxy function" means a group of atoms
wherein an oxygen atom is directly bound to two adjacent or non
adjacent carbon atoms in a carbon chain or in a cyclic carbon
system. Amongst the epoxy functions, oxirane functions are
preferred, that is to say three-membered, saturated, cyclic ether
groups.
[0079] Preferred R or R' groups do correspond to following formulas
V and VI:
##STR00001##
[0080] wherein R.sup.2 is an alkyl group, preferably a methyl
group, or a hydrogen atom, most preferably a hydrogen atom, a and c
are integers ranging from 1 to 6, and b is 0, 1 or 2.
[0081] The preferred group of formula V is the
.gamma.-glycidoxypropyl group (R.sup.2.dbd.H, a=3, b=0) and the
preferred (3,4-epoxycyclohexyl)alkyl group of formula VI is the
.beta.-(3,4-epoxycyclohexyl)ethyl group (c=1). The
.gamma.-glycidoxyethoxypropyl group may also be used
(R.sup.2.dbd.H, a=3, b=1).
[0082] The preferred epoxysilanes of formula I or III are
epoxyalkoxysilanes comprising preferably one R or R' group and
three alkoxy groups, the latter being directly bound to the silicon
atom. Particularly preferred epoxytrialkoxysilanes do correspond to
following formulas VII and VIII:
##STR00002##
[0083] wherein R.sup.1 is an alkyl moiety having from 1 to 6 carbon
atoms, preferably a methyl or an ethyl moiety, and a, b and c are
such as defined hereabove.
[0084] Examples of such epoxysilanes encompass
.gamma.-glycidoxypropyl triethoxysilane, .gamma.-glycidoxypropyl
trimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,
2-(3,4-epoxycyclohexyl)ethyltriethoxysilane. Other suitable
examples of useful epoxytrialkoxysilanes are given in the U.S. Pat.
No. 4,294,950. Amongst them, .gamma.-glycidoxypropyl
trimethoxysilane (GLYMO) is the most preferred.
[0085] Epoxysilanes I or III may optionally comprise a monovalent
organic Y or Y' group, directly bound to the silicon atom through a
Si--C linkage. These groups may be hydrocarbon groups, saturated or
not, preferably C.sub.1-C.sub.10 and more preferably
C.sub.1-C.sub.4 groups, for example an alkyl group, preferably a
C.sub.1-C.sub.4 alkyl group, such as a methyl or an ethyl group, an
alkenyl group such as a vinyl group, a C.sub.6-C.sub.10 aryl group,
for example a phenyl group, optionally substituted, particularly by
one or more C.sub.1-C.sub.4 alkyl group(s), a (meth)acryloxyalkyl
group, or they may represent the fluorinated or perfluorinated
analog groups of the hereabove mentioned hydrocarbon groups, for
example fluoroalkyl or perfluoroalkyl groups, or (poly)fluoro or
perfluoro alkoxy[(poly)alkylenoxy]alkyl groups.
[0086] Y (or Y') groups preferably do not comprise any function
that might react with the hydrolyzed silanes present in the upper
(or lower) layer composition, and particularly with the SiOH and/or
epoxy moieties of these silanes. Most preferably, Y (or Y')
represents an alkyl group, preferably a C.sub.1-C.sub.4 alkyl
group, and more preferably a methyl group.
[0087] Preferred epoxysilanes I or III comprising a Y or Y' group
are epoxydialkoxysilanes such as .gamma.-glycidoxypropyl(methyl)
dimethoxysilane, .gamma.-glycidoxypropyl(methyl) diethoxysilane and
.gamma.-glycidoxyethoxypropyl(methyl) dimethoxysilane. When used,
epoxydialkoxysilanes are preferably combined with
epoxytrialkoxysilanes such as those described hereabove, and are
then preferably used in lower amounts as compared to said
epoxytrialkoxysilanes.
[0088] Compounds of formulas II and IV will now be described
simultaneously. Naturally, the nature of compound II present in the
upper layer and that of compound IV present in the lower layer are
independent. This means, for example, that the nature of the Z
groups is independent from that of the Z' groups.
[0089] Z or Z' groups are hydrolyzable groups that may be selected,
independently from each other, from the hydrolyzable groups that
were previously mentioned for the description of X and X' groups.
It should be noted that M-OH or M'-OH functions may be initially
present in compounds of formulas II or IV, and if so, they are
considered as being hydrolyzates.
[0090] M and M' represent, independently from each other, metals or
metalloids, which respective valences x or y are equal to or higher
than 4, and do typically vary from 4 to 6. They are preferably
tetravalent or pentavalent. Preferably, compounds II or IV are
tetravalent species (x=4. y=4). M or M' represents atoms selected
for example from metals such as Sn, transition metals such as Zr,
Hf, Nb, Cr, Ta, W or Ti or metalloids such as silicon or germanium.
The antimony in its pentavalent form is also suitable. M or M'
preferably corresponds to silicon, zirconium, aluminium or
titanium, most preferably silicon.
[0091] Thus, preferred compound II is a compound of formula
Si(Z).sub.4, wherein the Z groups, being the same or different, are
hydrolyzable groups, and preferred compound IV is a compound of
formula Si(Z').sub.4, wherein Z' groups, being the same or
different, are hydrolyzable groups.
[0092] Amongst those compounds, preferred compounds II or IV are
tetraalkyl orthosilicates (or tetraalkoxysilane). Tetraethoxysilane
(or tetraethyl orthosilicate) Si(OC.sub.2H.sub.5).sub.4 noted TEOS,
is advantageously employed, as well as tetramethoxysilane
Si(OCH.sub.3).sub.4 noted TMOS, tetra(n-propoxy)silane,
tetra(i-propoxy)silane, tetra(n-butoxy)silane,
tetra(sec-butoxy)silane or tetra(t-butoxy)silane, and preferably
TEOS.
[0093] Surprisingly, the inventors discovered that using a silica
matrix precursor such as TEOS was better than using colloidal
silica, which will clearly appear hereafter in the description of
the examples. Coatings based on a composition comprising a mixture
of epoxyalkoxysilane and colloidal silica, broadly used in the
previous art, do result in coatings which performances as regards
abrasion and/or scratch resistance, especially abrasion resistance,
are lower than those of the abrasion-resistant coatings according
to the invention.
[0094] In the upper layer or lower layer compositions of the
invention, compounds I to IV may be either partially or totally
hydrolyzed. Advantageously, they are totally hydrolyzed. It is
preferred for hydrolyzing to use an at least stoichiometric amount
of water, that is to say a molar amount of water corresponding at
least to the mole number of hydrolyzable groups.
[0095] Hydrolyzates are prepared in a way that is known per se. The
methods illustrated in the patents FR 2702486 and U.S. Pat. No.
4,211,823 may in particular be employed.
[0096] Hydrolyzates of compounds I to IV may be prepared by adding
water to the compositions or an organic solvent or a mixture of
water and organic solvent, and preferably a catalyst for
hydrolyzing the X, X', Z or Z' groups, such as a mineral acid,
typically an aqueous solution of hydrochloric, sulfuric, nitric or
phosphoric acid or an organic acid organic such as acetic acid,
preferably HCl or H.sub.3PO.sub.4.
[0097] Organic solvents or the mixture of organic solvents suitably
used for the hydrolysis step are preferably polar solvents,
particularly alkanols such as methanol, ethanol, isopropanol,
isobutanol, n-butanol, propylene glycol methyl ethers and mixtures
thereof. Other solvents may be used, for example ketones such as
acetone, ethers such as tetrahydrofurane or 1,4-dioxane,
acetonitrile, aromatic solvents such as toluene or xylene or alkyl
chlorides. Methanol is the most preferred organic solvent.
[0098] The compositions of the abrasion-resistant coating according
to the invention comprise, after hydrolysis, preferably at least 1%
by weight of water as related to the weight of said composition.
This water may result from the partial hydrolysis of the initial
silanes, from the condensation reaction of the silanols formed
during this hydrolysis or from using an excessive amount of
water.
[0099] After the step for hydrolyzing the precursor compounds I to
IV, which does typically last for 1 h to 24 h, preferably 2 h to 6
h, at least one condensation catalyst and/or at least one curing
catalyst may optionally be added to the compositions of the lower
and/or higher abrasion-resistant layer so as to reduce the
temperature and the condensation and curing times. Many examples of
useful condensation and/or curing catalysts are given in the
following literature "Chemistry and Technology of the Epoxy
Resins", B. Ellis (Ed.) Chapman Hall, New York, 1993 and "Epoxy
Resins Chemistry and Technology" 2d Ed., C. A. May (Ed.), Marcel
Dekker, New York, 1988.
[0100] As useful condensation catalysts for the hydrolyzed
compounds I to IV, polyfunctional, saturated or unsaturated acids
or acid anhydrides may be mentioned. As used herein, a
"polyfunctional acid or acid anhydride" means an acid or an acid
anhydride comprising several acid or acid anhydride functions.
There are preferably compounds of carboxylic nature, including for
example maleic, chloromaleic, fumaric, itaconic, citraconic,
tetrahydrophthalic, trimellitic, oxalic, chlorendic
(1,4,5,6,7,7-hexachlorobicyclo[2.2.1]-hept-5-ene-2,3-dicarboxylic
acid) acids and maleic, itaconic, phthalic, hexahydrophthalic,
hexahydro-4-methylphthalic, tetrachlorophthalic, citraconic,
1,2-trimellitic (1,2,4-benzenetricarboxylic), 1,2-cyclohexane
dicarboxylic, bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic,
methylbicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic,
bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic, dodecenylsuccinic,
dichloromaleic anhydrides, pyromellitic dianhydride, and mixtures
thereof. Non carboxylic acids or anhydrides such as vanadic
anhydride may also be used. Preferred condensation catalysts are
maleic acid, itaconic acid, trimellitic acid and trimellitic
anhydride.
[0101] Curing catalysts do particularly act on the polymerization
of the epoxy functions and do favour the action of the condensation
catalysts. The compounds that can be employed encompass the
imidazole derivatives and their imidazolium salts, N-cyanoguanidine
(H.sub.2NC(.dbd.NH)NHCN, cyanamide dimer), also known under the
name dicyandiamide, acetylacetone metallic salts of formula
M(CH.sub.3COCHCOCH.sub.3).sub.n, wherein M is a metallic ion,
preferably Zn.sup.2+, Co.sup.3+, Fe.sup.3+ or Cr.sup.3+, and n is
an integer ranging typically from 1 to 3, preferably corresponding
to the metal M oxidation level, ammonium tetrathiocyanatodiamine
chromate(III) NH.sub.4[Cr(SCN).sub.4(NH.sub.3).sub.2], also known
under the name Reinecke salt, compounds based on aluminium,
metal-based carboxylates such as zinc, titanium, zirconium, tin or
magnesium, for example zinc octoate or stannous octoate, iodonium
salts such as hexafluoroantimonates and diaryliodonium
tetrakis(pentafluorophenyl)borate, sulfonium salts such as
triarylsulfonium hexafluorophosphates and hexafluoroantimonates,
and mixtures thereof.
[0102] Non limitative examples of imidazole derivatives that may be
used as curing catalysts are 2-alkyl imidazoles such as 2-methyl
imidazole, 2-phenyl-4-methyl imidazole or 2-propyl-4-methyl
imidazole, 1-cyanoalkyl imidazoles such as 1-cyanoethyl-2-methyl
imidazole, 1-cyanoethyl-2,4-dimethyl imidazole or
1-cyanoethyl-2-phenyl-4,5-dicyanoethoxymethyl imidazole, and
5-hydroxyalkyl imidazoles such as 2-phenyl-4-methyl-5-hydroxymethyl
imidazole or 2-phenyl-4,5-dihydroxymethyl imidazole. Other examples
of such compounds are given in the U.S. Pat. No. 4,294,950.
[0103] Non limitative examples of aluminium-based compounds that
may be used as curing catalysts are aluminium chelates and
aluminium(III) acylates and alcoholates of preferred general
formulas Al(OC(O)R).sub.n(OR').sub.3-n and
Al(OSiR''.sub.3).sub.n(OR').sub.3-n, wherein R and R' are linear or
branched chain alkyl groups containing from 1 to 10 carbon atoms,
R'' is a linear or branched chain, alkyl group containing from 1 to
10 carbon atoms, a phenyl moiety, an acylate moiety of formula
OC(O)R, wherein R is as defined hereabove, and n is an integer from
1 to 3. Preferably, R' is an isopropyl or ethyl group, R and R''
are methyl groups.
[0104] Aluminium chelates may be formed by reacting an aluminium
alcoholate or acylate with chelating agents free from nitrogen or
sulfur, comprising oxygen as a coordinating atom, for example
acetylacetone, ethyl acetoacetate or diethyl malonate. They may be
chosen from aluminium acetylacetonate noted Al(acac).sub.3, ethyl
mono(acetoacetate) aluminium bisacetylacetonate, ethyl
bis(acetoacetate) aluminium monoacetyl acetonate, di-n-butoxy
aluminium ethyl mono(acetoacetate) and di-i-propoxy aluminium ethyl
mono(acetoacetate). Other examples of such compounds are given in
the patent EP 0614957. When the curing catalyst is an aluminium
chelate, the coating composition preferably comprises an organic
solvent which boiling temperature at the atmospheric pressure does
range from 70 to 140.degree. C., for example ethanol, isopropanol,
ethyl acetate, methylethylketone or the tetrahydropyrane.
[0105] Preferably, a combination of itaconic acid and
N-cyanoguanidine or an aluminium chelate such as aluminium
acetylacetonate is used as a catalytic system in the
abrasion-resistant coating compositions of the invention.
Abrasion-resistant coating compositions comprising a mixture of
compounds I/II or III/IV, for example the upper layer compositions,
or the lower layer compositions, preferably comprise a combination
of itaconic acid and N-cyanoguanidine as a catalytic system.
[0106] Without wishing to be bound by any theory, the inventors
think that beyond a certain amount of II or IV type crosslinking
agents, using a catalytic system as active as an aluminium chelate
leads to a cured layer with an excessively high crosslinking
rate.
[0107] It is thus preferred that the lower layer compositions
comprising more than 10% by weight of compounds IV as related to
the composition weight, do not comprise any aluminium chelate.
[0108] Curing and condensation catalysts are used in usual amounts
in order to obtain the condensation and the hardening of the
compositions of the invention within a time period of about a few
hours at temperatures of about 100.degree. C. Curing catalysts are
typically used in an amount ranging from 0 to 5% by weight as
related to the total weight of the upper (or lower) layer
composition, preferably from 0.1 to 3%. Condensation catalysts are
typically used in an amount ranging from 0 to 10% by weight as
related to the total weight of the upper (or lower) layer
composition, preferably from 0 to 8%.
[0109] Both abrasion-resistant coating compositions of the
invention may contain additives traditionally used in the
abrasion-resistant and/or scratch-resistant coating compositions,
such as surfactants which improve the deposition optical quality,
preferably fluorine or silicone type surfactants, stabilizers, for
example additives to extend the shelf life of the compositions such
as chelating agents of the .beta.-diketone or .beta.-ketoester
type, as for example acetylacetone or ethyl acetoacetate, fillers,
pigments, dyes, UV absorbers, antioxidants, additional crosslinking
agents and optionally photo-initiators if the compositions do
contain photopolymerizable compounds.
[0110] The upper or lower layer compositions of the invention may
contain fillers in a small amount, typically one or more mineral
filler(s) that are intended to increase the hardness and/or the
refractive index of the coating once cured.
[0111] Mineral fillers may be selected from metal or metalloid
oxides or fluorides such as Si, Sb, Ti, Ta, Zr, Al, Ce, Sn, In, W
and mixtures thereof, preferably silica, titanium dioxide,
Sb.sub.2O.sub.5, ZrO.sub.2, Al.sub.2O.sub.3 and/or mixed oxides
such as TiO.sub.2/ZrO.sub.2, TiO.sub.2/ZrO.sub.2/SiO.sub.2 and
TiO.sub.2/Fe.sub.2O.sub.3 (composite particles of these oxides).
Preferably, mineral fillers are used in a colloidal form, that is
to say in the form of fine particles which diameter (or the longest
side) is preferably lower than 1 .mu.m, more preferably lower than
150 nm and even more preferably lower than 100 nm, dispersed in a
dispersing medium, such as water, an alcohol, a ketone, an ester or
mixtures thereof, preferably an alcohol. Colloidal silica is a
suitable example of such a filler, for example the silica from
Nissan Sun Colloid Mast which comprises 30% by weight of SiO.sub.2
as a solid matter suspended in methanol.
[0112] According to a preferred embodiment, the upper layer
composition and/or the lower layer composition of the invention
comprises less than 10% by weight of fillers (solids) as related to
the total weight of the composition, more preferably is free from
any filler. In particular, it is preferred that the upper layer
composition and/or the lower layer composition of the invention
comprises less than 10% by weight of colloidal silica as related to
the total weight of the composition, more preferably is free from
any colloidal silica.
[0113] Preferably, the filler total weight present in the upper
layer composition and/or the lower layer composition, in other
words the theoretical dry matter weight of fillers represents less
than 30% of the theoretical dry matter weight of the composition,
more preferably less than 20% and even more preferably less than
10%. Such preferences do also apply to the colloidal silica
theoretical dry matter weight.
[0114] As used herein, the "theoretical dry matter weight of a
composition component" means the theoretical weight of solids
represented by this component in said composition, that is to say
its weight contribution to the theoretical dry matter weight of the
composition.
[0115] The theoretical dry matter weight of a composition is
defined as being the sum of all component theoretical dry matter
weights.
In the present context, the "theoretical dry matter weight of
component I, II, III or IV" means: [0116] for compounds I and III,
the weight of said compounds as calculated in
R.sub.nY.sub.mSi(O).sub.(4-n-m)/2 or
R'.sub.n'Y'.sub.m'Si(O).sub.(4-n'-m')/2 units, wherein R, Y, n, m,
R', Y', n' and m' are such as previously defined; [0117] for
compounds II and IV, the weight of said compounds as calculated in
M(O).sub.x/2 or M'(O).sub.y/2 units, wherein M, M', x and y are
such as previously defined.
[0118] The theoretical dry matter weight of component I, II, III or
IV is lower than the weight of component I, II, III or IV actually
used. The theoretical dry matter weight of catalysts or mineral
fillers is typically equal to the weight of compounds actually
used.
[0119] The upper and lower abrasion-resistant layer compositions of
the invention may contain in some embodiments the same compound
categories, but they are different as regards the contents of their
components.
[0120] Thus, the Rs ratio is lower than or equal to 2.3, preferably
lower than or equal to 2.0, more preferably lower than or equal to
1.5, even more preferably lower than or equal to 1.25, and most
preferably is lower than or equal to 1.1, Rs being defined as
follows:
Rs = theoretical dry matter weight of compounds I in the upper
layer composition theoretical dry matter weight of compounds I I in
the upper layer composition ##EQU00005##
[0121] This definition of The Rs ratio does imply that an upper
layer composition free from any component II does not correspond to
the definition of the invention. Rs is preferably higher than or
equal to 0.85, more preferably higher than or equal to 0.9, even
more preferably higher than or equal to 0.95.
[0122] The theoretical dry matter weight of compounds I represents
preferably from 30 to 60% of the upper layer composition dry matter
weight, more preferably from 40 to 55%. The theoretical dry matter
weight of compounds II represents preferably from 30 to 60% of the
upper layer composition dry matter weight, more preferably from 40
to 55%. The sum of the theoretical dry matter weights of compounds
I and II represents preferably at least 75% of the lower layer
composition dry matter weight, more preferably at least 80%, even
more preferably at least 85%.
[0123] The upper layer composition dry matter weight represents
preferably from 5 to 40%, more preferably from 15 to 25% by weight,
as related to the total weight of the composition.
[0124] The upper layer composition does preferably comprise from 5
to 30% by weight of compounds I as related to the composition
weight, preferably from 10 to 25%, more preferably from 10 to 20%.
The upper layer composition does preferably comprise from 15 to 50%
by weight of compounds II as related to the composition weight,
preferably from 20 to 40%, more preferably from 25 to 40%.
[0125] The sum of the weights of compounds I and II represents
preferably from 25 to 65% of the upper layer composition weight,
preferably from 30 to 60%, more preferably from 35 to 55%. The
weight ratio of compounds I to compounds II in this composition
does preferably range from 0.25 to 0.60, more preferably from 0.30
to 0.60, and even more preferably from 0.35 to 0.45.
[0126] Ratio Ri is higher than 2.3, preferably higher than or equal
to 3.0, more preferably higher than or equal to 3.5, even more
preferably higher than or equal to 4.5, and most preferably is
higher than or equal to 10, Ri being defined as follows:
Ri = theoretical dry matter weight of compounds III in the lower
layer composition theoretical dry matter weight of compounds I V in
the lower layer composition ##EQU00006##
[0127] This definition of ratio Ri does imply that a lower layer
composition free from any component IV corresponds to the
definition of the invention, where Ri does indeed tend to
infinity.
[0128] The theoretical dry matter weight of compounds III
represents preferably more than 40% of the lower layer composition
dry matter weight, more preferably more than 50%, even more
preferably more than 60% and most preferably more than 65%. The
theoretical dry matter weight of compounds IV represents preferably
less than 30% of the lower layer composition dry matter weight,
more preferably less than 25%, even more preferably less than 20%
and most preferably less than 10%. The sum of the theoretical dry
matter weights of compounds III and IV represents preferably at
least 70% of the lower layer composition dry matter weight, more
preferably at least 75%, even more preferably at least 80%.
[0129] The theoretical dry matter weight of the lower layer
composition represents preferably from 10 to 50%, more preferably
from 25 to 40% by weight, as related to the total weight of the
composition.
[0130] The lower layer composition does preferably comprise from 15
to 70% by weight of compounds III as related to the composition
weight, preferably from 20 to 60%, more preferably from 25 to 55%.
The lower layer composition does preferably comprise from 0 to 35%
by weight of compounds IV as related to the composition weight,
preferably from 0 to 25%, more preferably from 0 to 15% and even
more preferably from 0 to 10%. According to a particular
embodiment, the lower layer composition does not comprise any
compound of formula IV or any hydrolyzate of compounds of formula
IV.
[0131] The sum of the weights of compounds III and IV represents
preferably from 25 to 75% of the lower layer composition weight,
preferably from 30 to 70%, more preferably from 35 to 65%. The
weight ratio of compounds III to compounds IV in this composition
is preferably higher than or equal to 1.25, more preferably higher
than or equal to 1.50, even more preferably higher than or equal to
1.75. According to a particular embodiment, this ratio is higher
than or equal to 4.
[0132] In the final optical article, the thickness of the abrasion-
and scratch-resistant coating of the invention does typically vary
from 1 to 15 .mu.m, preferably from 1 to 10 .mu.m, more preferably
from 2 to 8 .mu.m, and even more preferably from 3 to 6 .mu.m. The
thickness of the abrasion-resistant coating lower layer does
preferably vary from 1 to 6 .mu.m, more preferably from 2 to 5
.mu.m, and even more preferably from 3 to 5 .mu.m and the thickness
of the abrasion-resistant coating upper layer does independently
vary preferably from 0.5 to 4 .mu.m, more preferably from 0.7 to 2
.mu.m and even more preferably from 0.7 to 1.5 .mu.m. The thickness
ratio of the lower layer to the upper layer is preferably higher
than or equal to 1.5, more preferably higher than or equal to 2.0,
and even more preferably higher than or equal to 3.0.
[0133] A supplementary abrasion-resistant and/or scratch-resistant
coating layer may optionally be deposited onto the upper layer of
the bilayered coating of the invention. It will be typically called
"supplementary abrasion-resistant and/or scratch-resistant layer".
This supplementary layer and said upper layer are preferably
adjacent to each other, that is to say directly contacting with and
adhering to each other.
[0134] The supplementary abrasion-resistant and/or
scratch-resistant layer is a cured layer of a supplementary
abrasion-resistant and/or scratch-resistant composition, which
comprises: [0135] at least one organosilane compound, or a
hydrolyzate thereof, of formula:
[0135] R''.sub.n''Y''.sub.m''Si(X'').sub.4-n''-m'' (IX)
[0136] wherein the R'' groups, being the same or different, are
monovalent organic groups that are bound to silicon through a
carbon atom and that contain at least one epoxy function, wherein
the X'' groups, being the same or different, are hydrolyzable
groups, Y'' is a monovalent organic group bound to silicon through
a carbon atom, n'' and m'' being integers such that n''=1 or 2 with
n''+m''=1 or 2, and [0137] at least one compound, or a hydrolyzate
thereof, of formula:
[0137] M''(Z'').sub.z (X)
[0138] wherein M'' represents a metal or a metalloid, Z'' groups,
being the same or different, are hydrolyzable groups and z, equal
to or higher than 4, preferably from 4 to 6, is the metal or
metalloid M'' valence, the ratio:
Rss = theoretical dry matter weight of compounds IX in the
supplementary layer composition theoretical dry matter weight of
compounds X in the supplementary layer composition ##EQU00007##
being lower than or equal to 2.3 and strictly lower than ratio Rs
as previously defined, the theoretical dry matter weight of
compounds X representing at least 45% of the dry matter weight of
the supplementary abrasion-resistant and/or scratch-resistant layer
composition and the thickness of the supplementary
abrasion-resistant and/or scratch-resistant layer being lower than
that of the upper layer of the bilayered coating of the
invention.
[0139] The structural characteristics of the supplementary
abrasion-resistant and/or scratch-resistant layer, and those
concerning its preparation, may be selected from the ones which
have been previously described for the upper layer of the bilayered
coating of the invention, and for this reason they will not be
repeated, except however the characteristics concerning ratio Rss,
the thickness of this layer and the theoretical dry matter weight
content for epoxysilanes of formula X as related to the dry matter
weight of the composition, which are different.
[0140] Thus, for example, epoxysilanes of formula IX may be
selected from the previously mentioned compounds as related to the
description of compounds of formula I, and compounds of formula X
may be selected from the previously mentioned compounds as related
to the description of compounds of formula II.
[0141] Preferably, the theoretical dry matter weight of compounds X
represents at least 50% of the dry matter weight of the
supplementary abrasion-resistant and/or scratch-resistant layer
composition, and preferably 65% or less, more preferably 60% or
less, the most preferred range varying from 55 to 60%.
[0142] In the final optical article, the thickness of the
abrasion-resistant and/or scratch-resistant additional layer, while
being lower than that of the upper layer of the bilayered coating
of the invention, does preferably vary from 0.5 to 2 .mu.m, more
preferably from 0.5 to 1.5 .mu.m.
[0143] Ratio Rss is strictly lower than ratio Rs, which makes it
possible to obtain a hardness gradient by increasing the ratio of
II/IV/X type compounds from the abrasion-resistant lower layer to
the supplementary abrasion-resistant and/or scratch-resistant
layer. Rss is preferably lower than or equal to 2.0, more
preferably lower than or equal to 1.5, even more preferably lower
than or equal to 1.25, and most preferably is lower than or equal
to 1.1. Rss is preferably higher than or equal to 0.85, more
preferably higher than or equal to 0.9, even more preferably higher
than or equal to 0.95. Preferably, the optical article of the
invention comprises 4 or less abrasion-resistant and/or
scratch-resistant coating layers, more preferably 3 or less
abrasion-resistant and/or scratch-resistant coating layers, and
even more preferably 2 abrasion- and scratch-resistant coating
layers, that is to say it does not comprise any further
abrasion-resistant and/or scratch-resistant layers than those of
the bilayered coating of the invention.
[0144] An antireflective coating may optionally be deposited onto
the abrasion- and scratch-resistant coating, that is to say on its
upper layer, or onto the supplementary abrasion-resistant and/or
scratch-resistant layer. An antireflective coating is defined as a
coating, deposited on the surface of an optical article, which
improves the antireflective properties of the final optical
article. It makes it possible to reduce the light reflection at the
article-air interface over a relatively broad portion of the
visible spectrum.
[0145] Antireflective coatings are well known and traditionally
comprise a monolayered or a multilayered stack of dielectric
materials such as SiO, SiO.sub.2, Al.sub.2O.sub.3, MgF.sub.2, LiF,
Si.sub.3N.sub.4, TiO.sub.2, ZrO.sub.2, Nb.sub.2O.sub.5,
Y.sub.2O.sub.3, HfO.sub.2, Sc.sub.2O.sub.3, Ta.sub.2O.sub.5,
Pr.sub.2O.sub.3, or mixtures thereof.
[0146] As is also well known, antireflective coatings are
preferably, multilayered coatings comprising high refractive index
(HI) layers and low refractive index (LI) layers, alternately.
Advantageously, the LI layers of the antireflective coating
comprise a mixture of SiO.sub.2 and Al.sub.2O.sub.3.
[0147] In the present application, a layer of an antireflective
stack is said to be a high refractive index layer when its
refractive index is higher than 1.55, preferably higher than or
equal to 1.6, more preferably higher than or equal to 1.8 and even
more preferably higher than or equal to 2.0. A layer of an
antireflective stack is said to be a low refractive index layer
when its refractive index is lower than or equal to 1.55,
preferably lower than or equal to 1.50, more preferably lower than
or equal to 1.45.
[0148] Unless otherwise specified, the refractive indices which it
is referred to in the present invention are expressed at 25.degree.
C. for a wavelength of 550 nm.
[0149] Preferably, total physical thickness of the antireflective
coating is lower than 1 micrometer, more preferably lower than or
equal to 500 nm and even more preferably lower than or equal to 250
nm. The total physical thickness of the antireflective coating is
typically higher than 100 nm, preferably higher than 150 nm.
[0150] It is possible to interleave a sub-layer, typically a
SiO.sub.2 sublayer, between the antireflective coating and the
underlying coating, which is typically the abrasion- and
scratch-resistant coating, so as to improve the abrasion and/or
scratch resistance of the antireflective coating and to increase
its adhesion to the underlying coating.
[0151] The antireflective coating is typically applied by vacuum
deposition according to any of following procedures: i) by
evaporation, optionally ion beam assisted; ii) by ion beam
sputtering; iii) by cathode sputtering; iv) by plasma-assisted
chemical vapour deposition.
[0152] In addition to the vacuum deposition methods, it is possible
to apply a multilayered antireflective coating using a wet process,
particularly by spin-coating liquid compositions containing a
silane hydrolyzate and colloidal materials having a high or low
refractive index. Such coatings which layers comprise an
organic/inorganic hybrid matrix based on silanes wherein colloidal
materials are dispersed to adjust the refractive index of each
layer are described for example in the French patent FR
2858420.
[0153] However, an antireflective coating comprising a stack
exclusively comprising mineral dielectric layers is preferred. It
does preferably comprise a stack of at least three dielectric
layers with high refractive index and low refractive index layers,
alternately.
[0154] The optical article of the invention may also comprise
coatings formed on the antireflective coating that are able to
modify its surface properties, such as hydrophobic coatings and/or
oleophobic coatings (anti-fouling top coat). These coatings are
preferably applied onto the outer layer of the antireflective
coating. Their thickness is generally lower than or equal to 10 nm,
and preferably ranges from 1 to 10 nm, more preferably from 1 to 5
nm.
[0155] They are typically fluorosilane or fluorosilazane type
coatings. They may be obtained by depositing a fluorosilane or
fluorosilazane precursor, comprising preferably at least two
hydrolyzable groups per molecule. Fluorosilane precursors
preferably comprise fluoropolyether moieties and more preferably
perfluoropolyether moieties. These fluorosilanes are well known and
are described, amongst others, in the U.S. Pat. No. 5,081,192, U.S.
Pat. No. 5,763,061, U.S. Pat. No. 6,183,872, U.S. Pat. No.
5,739,639, U.S. Pat. No. 5,922,787, U.S. Pat. No. 6,337,235, U.S.
Pat. No. 6,277,485 and in the European patent application EP
0933377.
[0156] A preferred hydrophobic and/or oleophobic coating
composition is marketed by Shin-Etsu Chemical under the trade name
KP 801M.RTM.. Another preferred hydrophobic and/or oleophobic
coating composition is marketed by Daikin Industries under the
trade name OPTOOL DSX.RTM.. It is a fluorinated resin comprising
perfluoropropylene groups.
[0157] Typically, an optical article of the invention comprises a
substrate successively coated with an impact-resistant primer
layer, the bilayered scratch-resistant and abrasion-resistant
coating of the invention, an antireflective stack and a hydrophobic
and/or oleophobic coating. The article of the invention is
preferably an optical lens, more preferably an ophthalmic lens for
spectacles, or an optical or ophthalmic lens blank. The lens may be
a polarized lens or a photochromic lens.
[0158] The present invention further relates to a method for making
an abrasion- and scratch-resistant optical article such as defined
hereabove, comprising at least the steps of:
[0159] a) providing an optical article comprising a substrate
having at least one main surface;
[0160] b) depositing onto a substrate main surface a layer of a
lower layer composition such as previously defined;
[0161] c) at least partially curing said lower layer composition
using a thermal process;
[0162] d) depositing onto the layer resulting from the previous
step a layer of an upper layer composition such as previously
defined;
[0163] e) curing said upper layer composition using a thermal
process;
[0164] f) recovering an optical article comprising a substrate
having a main surface coated with an abrasion- and
scratch-resistant coating composed of a lower layer adhering to an
upper layer.
[0165] The lower layer composition may be deposited onto the
substrate of the optical article according to any known suitable
method, for example by dip coating, by spin coating, spraying,
wetting or roll or brush coating, preferably by dip coating or by
spin coating.
[0166] In a first alternative of the method, the lower layer
composition is totally cured using a thermal process prior to
depositing the upper layer composition, during step c). The curing
is carried out preferably at a temperature ranging from 80 to
150.degree. C., more preferably from 90 to 120.degree. C.,
typically for 30 minutes to 4 hours.
[0167] Preferably, the optical article surface resulting from step
c), that is to say the lower layer, does undergo a surface
preparative treatment before the step of depositing the upper layer
composition onto its surface (step d)).
[0168] This physical or chemical activating treatment, which is
intended to increase the upper layer adhesion, is typically
conducted under vacuum. It may comprise bombarding with the
energetic species as previously defined, for example using an ion
beam ("Ion Pre-Cleaning" or "IPC") or an electron beam, by a corona
discharge treatment, by ion spallation, an ultraviolet treatment, a
plasma treatment under vacuum, typically an oxygen or an argon
plasma, an acidic or a basic treatment and/or using solvents (water
or an organic solvent). Several of these treatments may be
associated.
[0169] The surface preparation intermediate step is preferably a
treatment using a basic solution, which comprises typically a few
minute-long etching step (for 1 to 3 minutes) at temperatures
approaching 40-50.degree. C. in a 5% weight soda bath optionally
containing surfactants.
[0170] The upper layer composition may be deposited onto the
abrasion-resistant coating lower layer according to the same method
than for the lower layer composition and may be cured using a
thermal process in similar conditions as for it.
[0171] In a second alternative of the method, the lower layer
composition is only partially cured using a thermal process prior
to depositing the upper layer composition, during step c). This
step, which may be defined as a prepolymerization or precuring
step, is typically carried out at a temperature ranging from 70 to
120.degree. C., preferably from 80 to 120.degree. C., more
preferably from 85 to 110.degree. C., even more preferably from 90
to 100.degree. C., for a relatively short time, typically for 1 to
30 minutes, more preferably for 3 to 20 minutes and even more
preferably for 5 to 10 minutes.
[0172] Surprisingly, the present inventors did observe that a too
long curing time could lead to a deterioration of the abrasion
resistance properties of the final coating.
[0173] The second alternative of the method of the invention
surprisingly enables omitting the previously described intermediate
surface preparation between depositing the lower layer and the
upper layer, which is particularly advantageous as regards the
implementation on an industrial scale. Despite the omission of the
intermediate step for preparing the lower layer surface, a very
good adhesion is obtained in the final product between the two
layers of the abrasion-resistant coating.
[0174] Thus, according to the second alternative of the method, the
surface of the article resulting from step c) does not undergo
before step d) a surface preparation treatment and the upper layer
composition may be deposited directly onto the abrasion-resistant
coating lower layer resulting from step c), according to the same
methods as mentioned hereabove.
[0175] The upper layer composition may then be cured using a
thermal process preferably at a temperature ranging from 80 to
150.degree. C., preferably from 90 to 120.degree. C., typically for
30 minutes to 4 hours, which does also complete the curing of the
lower layer composition.
[0176] When a supplementary abrasion-resistant and/or
scratch-resistant coating layer is required to be deposited onto
the upper layer of the bilayered coating of the invention, steps e)
and f) of the method of the invention then become:
[0177] e) at least partially curing said upper layer composition
using a thermal process;
[0178] e1) depositing onto the layer resulting from the previous
step a layer of a supplementary abrasion-resistant and/or
scratch-resistant layer composition such as previously defined;
[0179] e2) curing said supplementary layer composition using a
thermal process;
[0180] f) recovering an optical article composed of a substrate
having a main surface coated with an abrasion- and
scratch-resistant coating composed of a lower layer adhering to an
upper layer, and coated with a supplementary layer of
abrasion-resistant and/or scratch-resistant coating adhering to
said upper layer.
[0181] Said upper layer may undergo a surface preparation treatment
prior to depositing the supplementary layer composition onto its
surface. Such physical or chemical activating treatment, intended
to increase the adhesion of the supplementary layer, may be
selected, without limitation, from the lower layer activating
treatments as described hereabove.
[0182] In a first alternative, the upper layer composition is
totally cured using a thermal process prior to depositing the
supplementary abrasion-resistant and/or scratch-resistant layer
composition. Its curing is carried out preferably at a temperature
ranging from 80 to 150.degree. C., preferably from 90 to
120.degree. C., typically for 30 minutes to 4 hours.
[0183] In a second alternative, said upper layer composition may be
only partially cured using a thermal process prior to depositing
the composition of the supplementary layer. This step, which may be
defined as being a prepolymerization or precuring step, is
typically carried out at a temperature ranging from 80 to
120.degree. C., preferably from 85 to 110.degree. C., more
preferably from 90 to 100.degree. C., for a relatively short time,
typically for 1 to 30 minutes, more preferably for 3 to 20 minutes
and even more preferably for 5 to 10 minutes. In this second
alternative, the upper layer surface of the bilayered coating of
the invention does preferably not undergo, before the step of
depositing the supplementary abrasion-resistant and/or
scratch-resistant layer, any surface preparation treatment and the
supplementary layer composition may be deposited directly onto the
upper layer of the bilayered coating.
[0184] Despite the omission of the intermediate step of preparation
of the lower layer surface, an excellent adhesion is obtained in
the final product between the abrasion-resistant coating upper
layer and said supplementary layer.
[0185] The supplementary layer composition may then be cured using
a thermal process preferably at a temperature ranging from 80 to
150.degree. C., preferably from 90 to 120.degree. C., typically for
30 minutes to 4 hours, thus also completing the curing of the upper
layer composition, and optionally lower layer composition.
[0186] The abrasion-resistant and/or scratch-resistant
supplementary layer composition may be deposited according to any
known suitable method, for example by dip coating, by spin coating,
spraying, wetting or roll or brush coating, preferably by dip
coating or by spin coating.
[0187] The optical article comprising a substrate onto which the
abrasion- and scratch-resistant coating of the invention has been
formed may also be a temporary support, onto which said coating is
stored, waiting for being transferred to another substrate, which
is typically the final substrate, such as a substrate for an
ophthalmic lens. In this case, the lower layer and the upper layer
of the bilayered coating should be deposited onto the temporary
support in reverse order as compared to the expected stacking order
on the final support.
[0188] The present invention thus further relates to a method for
making an abrasion- and scratch-resistant optical article such as
defined hereabove, comprising at least the steps of:
[0189] a) providing a temporary support having at least one main
surface;
[0190] b) depositing onto a support main surface a layer of an
upper layer composition such as previously defined;
[0191] c) at least partially curing said upper layer composition
using a thermal process;
[0192] d) depositing onto the layer resulting from the previous
step a layer of a lower layer composition such as previously
defined;
[0193] e) curing said lower layer composition using a thermal
process;
[0194] f) transferring the layers present on the temporary support
main surface onto an optical article substrate main surface;
[0195] g) recovering an optical article comprising a substrate
having a main surface coated with an abrasion- and
scratch-resistant coating composed of a lower layer adhering to an
upper layer.
[0196] Said temporary support may be rigid or flexible, preferably
flexible. It is a removable support, that is to say it is intended
to be removed once the transfer of the abrasion- and
scratch-resistant coating of the invention has been effected to the
support which is typically the final support.
[0197] The temporary support may be used, having previously been
coated with a release agent layer so as to facilitate the transfer.
Such layer may optionally be removed at the end of the transfer
step.
[0198] Flexible temporary supports are typically a few
millimetre-thick fine elements, that are preferably from 0.2 to 5
mm thick, more preferably from 0.5 to 2 mm thick, in a plastic
material, preferably a thermoplastic material.
[0199] Thinner films may also be used as temporary supports.
[0200] Examples of thermoplastic (co)polymers that can be suitably
used for making the temporary support encompass polysulfones,
aliphatic poly(meth)acrylates, such as methyl poly(meth)acrylate,
polyethylene, polypropylene, polystyrene, SBM bloc copolymers
(styrene, butadiene and methyl methacrylate), polyphenylene sulfide
(PPS), arylene polyoxides, polyimides, polyesters, polycarbonates
such as bisphenol A polycarbonate, polyvinyl chloride, polyamides
such as nylons, their copolymers and mixtures thereof.
Polycarbonate is the preferred thermoplastic material.
[0201] The temporary support main surface may comprise a stack of
one or more functional coating(s) (already described) which will be
transferred on the final support at the same time as the abrasion-
and scratch-resistant coating of the invention, in particular a
supplementary abrasion-resistant and/or scratch-resistant layer
such as previously defined. Of course, the coatings to be
transferred have been deposited onto the temporary support in
reverse order as compared to the expected stacking order on the
final support.
[0202] Moreover, further functional coatings may be formed on the
lower layer of the bilayered coating prior to conducting the
transfer.
[0203] The present invention further relates to a method for
transferring the abrasion- and scratch-resistant coating of the
invention (or a coating stack comprising said abrasion- and
scratch-resistant coating) from the temporary support to a final
substrate.
[0204] The transfer of the coating(s) applied on the temporary
support may be conducted according to any suitable method known by
the man skilled in the art.
[0205] II is also possible to bound the abrasion- and
scratch-resistant coating having been formed on a temporary
support, to the final substrate, rather than to transfer it, the
support being thus integrated to the final substrate.
[0206] The alternatives of the traditional deposition method may be
adapted to the process including a transfer step. Thus, for
example, the upper layer composition may be totally cured using a
thermal process prior to depositing the lower layer composition,
the upper layer may undergo a surface preparation treatment before
the deposition step on its surface of the lower layer composition,
and the upper layer composition may be only partially cured using a
thermal process prior to depositing the lower layer
composition.
[0207] Moreover, both layers of the bilayered scratch-resistant and
abrasion-resistant coating of the invention may be separately
transferred to a substrate, as well as any other coating such as a
supplementary abrasion-resistant and/or scratch-resistant
layer.
[0208] The following examples illustrate the invention in more
detail without being limitative in any way. Unless otherwise
specified, all percentages expressed are weight percentages.
EXAMPLES
1. General Procedures
[0209] The optical articles used in examples 1-8 and 11-15 comprise
an ORMA.RTM. lens substrate from ESSILOR having a 65 mm diameter, a
-2.00 dioptre power and being 1.2 mm thick, which convex face is
successively coated with: [0210] optionally a 1 .mu.m-thick layer
of a polyurethane type impact-resistant primer based on
Witcobond.RTM. 234 optionally filled (examples 15, 19, 21, 22);
[0211] optionally a 2.5 .mu.m-thick layer of an additional
abrasion-resistant and/or scratch-resistant monolayered coating
based on an epoxysilane hydrolyzate (example 18 only). The
formulation and the preparation method of such coating are
described in more detail hereunder; [0212] a bilayered
scratch-resistant and abrasion-resistant coating in accordance with
the invention, wherein the hardness gradient is obtained by
increasing the tetrathoxysilane rate from the abrasion-resistant
lower layer to the abrasion-resistant upper layer; [0213]
optionally a supplementary abrasion-resistant and/or
scratch-resistant coating layer (example 20); and [0214] optionally
an antireflective coating composed of a stack of four
ZrO.sub.2/SiO.sub.2/ZrO.sub.2/SiO.sub.2 layers formed by
evaporation under vacuum, that were respectively 27, 21, 80 and 81
nm thick (examples 1, 2, 4 and 5 only).
[0215] Examples 9, 10, 16 and 17 are comparative examples using
lower and/or upper layer compositions that are not in accordance
with the present invention.
[0216] a) Preparation of the Abrasion-Resistant Lower Layer
Compositions
[0217] Lower Layer Composition A:
[0218] 180 g of hydrochloric acid 0.1N were dropped into a solution
containing 280 g of Glymo and 150 g of tetrathoxysilane (TEOS).
During hydrolysis, the temperature raised up to 45.degree. C. The
hydrolyzed solution was stirred for 24 hours at room temperature,
then 45 g of itaconic acid, 14 g of N-cyanoguanidine, 330 g of
methanol and 1.5 g of surfactant FC 430 were added thereto, so as
to improve the spreading capacity of such formulation. The
theoretical dry matter (TDM) of this composition was of about 30%
by weight.
[0219] Lower Layer Composition A1:
[0220] 102.8 g of hydrochloric acid 0.1N were dropped into a beaker
containing 385.8 g of Glymo. During hydrolysis, the temperature
raised up to 40-42.degree. C. The hydrolyzed solution was stirred
for 24 hours at room temperature, then 61.6 g of itaconic acid,
15.4 g of N-cyanoguanidine, 432.9 g of methanol and 1.5 g of
surfactant FC 430 were added thereto. The theoretical dry matter
(TDM) of this composition was of about 35% by weight.
[0221] Lower Layer Composition A2:
[0222] 101.8 g of hydrochloric acid 0.1N were dropped into a beaker
containing 445.2 g of Glymo. During hydrolysis, the temperature
raised up to 43.degree. C. The hydrolyzed solution was stirred for
24 hours at room temperature, then 18.9 g of aluminium
acetylacetonate, 333 g of methanol and 1.5 g of surfactant FC 430
were added thereto. The theoretical dry matter (TDM) of this
composition was of about 35% by weight.
[0223] Lower Layer Composition A3:
[0224] 151.5 g of hydrochloric acid 0.1N were dropped into a
solution containing 365 g of Glymo and 196.6 g of tetrathoxysilane
(TEOS). During hydrolysis, the temperature raised up to 42.degree.
C. The hydrolyzed solution was stirred for 24 hours at room
temperature, then 18.9 g of aluminium acetylacetonate, 166.6 g of
methanol and 1.35 g of surfactant FC 430 were added thereto. The
theoretical dry matter (TDM) of this composition was of about 35%
by weight.
[0225] Lower Layer Composition A4 (Comparative Composition):
[0226] 64 g of hydrochloric acid 0.1N were dropped into 183 g of
Glymo under stirring.
[0227] During hydrolysis, the temperature raised up to 46.degree.
C. After 30 minutes, the hydrolyzate temperature had decreased to
28.degree. C., and 91 g of DMDES (dimethyl diethoxysilane) were
then dropped. This addition is slightly exothermic (29.degree.
C.).
[0228] The hydrolyzed solution was stirred for 24 hours at room
temperature, then 583.3 g of a colloidal silica dispersion
Suncolloid MAST from NISSAN, 30% dry matter in methanol, 10.5 g of
aluminium acetylacetonate, 31.5 g of methyl ethyl ketone, 35.2 g of
methanol and 1.5 g of surfactant FC 430 were added thereto. The
theoretical dry matter (TDM) of this composition was of about 35%
by weight.
[0229] Lower Layer Composition A5:
[0230] 2.15 g of phosphoric acid (purity: 99%) were dropped into a
solution containing 271.3 g of Glymo and 166.4 g of TEOS. During
hydrolysis, the temperature raised up to 45.degree. C. The
hydrolyzed solution was stirred for 24 hours at room temperature,
then 9.6 g of N-cyanoguanidine, 239.3 g of deionized water, 110.4 g
of 1-methoxypropan-2-ol marketed under the trade name DOWANOL
PM.RTM. by Dow Chemical and 0.8 g of surfactant EFKA.RTM. 3034
(Ciba Specialty Chemicals) were added thereto, so as to improve the
spreading capacity of such formulation. The theoretical dry matter
(TDM) of this composition was of about 31.2% by weight.
Remark: in comparative example 16, composition A5 was used as an
upper layer composition.
[0231] Lower Layer Composition A6:
[0232] 77.6 g of hydrochloric acid 0.1N were dropped into a beaker
containing 339.2 g of Glymo. During hydrolysis, the temperature
raised up to 40-42.degree. C. The hydrolyzed solution was stirred
for 24 hours at room temperature, then 10.8 g of itaconic acid, 3.4
g of N-cyanoguanidine, 367.9 g of methanol and 1.2 g of surfactant
EFKA.RTM. 3034 (Ciba Specialty Chemicals) were added thereto. The
theoretical dry matter (TDM) of this composition was of about
31.35% by weight.
[0233] Lower Layer Composition A7:
[0234] 102.4 g of hydrochloric acid 0.1N were dropped into a beaker
containing 224 g of Glymo and 120 g of TEOS. During hydrolysis, the
temperature raised up to 45.degree. C. The hydrolyzed solution was
stirred for 24 hours at room temperature, then 36 g of itaconic
acid, 11.2 g of N-cyanoguanidine, 264 g of methanol and 0.8 g of
surfactant EFKA.RTM. 3034 (Ciba Specialty Chemicals) were added
thereto. The theoretical dry matter (TDM) of this composition was
of about 30% by weight.
[0235] Lower Layer Composition A8:
[0236] This composition is obtained by mixing the components
mentioned in the table hereunder. The resulting layer has a high
refractive index because of the titanium-based colloid.
TABLE-US-00001 Components gram Glymo 174.88 HCl 0.1N 71.99
TiO.sub.2/SiO.sub.2/ZrO.sub.2 composite particle 609.61 colloid
(firm CCIC) Al(Acac).sub.3 9.08 Methyl ethyl ketone 27.23 Methanol
9.36 EFKA .RTM. 3034 1.50
[0237] b) Preparation of the Abrasion-Resistant Upper Layer
Compositions
[0238] Upper Layer Composition B:
[0239] 130.5 g of hydrochloric acid 0.1N were dropped into a
solution containing 126.1 g of Glymo and 294.4 g of TEOS. During
hydrolysis, the temperature raised up to 49.degree. C. The
hydrolyzed solution was stirred for 24 hours at room temperature,
then 20.8 g of itaconic acid, 5 g of N-cyanoguanidine, 423.1 g of
methanol and 1.5 g of surfactant FC 430 were added thereto, so as
to improve the spreading capacity of such formulation. The
theoretical dry matter (TDM) of this composition was of about 20%
by weight.
[0240] Upper Layer Composition B1:
[0241] 152.3 g of hydrochloric acid 0.1N were dropped into a
solution containing 141.3 g of Glymo and 346.7 g of TEOS. During
hydrolysis, the temperature raised up to 47.degree. C. The
hydrolyzed solution was stirred for 24 hours at room temperature,
then 12 g of aluminium acetylacetonate, 346 g of methanol and 1.5 g
of surfactant FC 430 were added thereto, so as to improve the
spreading capacity of such formulation. The theoretical dry matter
(TDM) of this composition was of about 20% by weight.
[0242] Upper Layer Composition B2 (Comparative Composition):
[0243] 29.1 g of hydrochloric acid 0.1N were dropped into a
solution containing 127.2 g of Glymo. During hydrolysis, the
temperature raised up to 45.degree. C. The hydrolyzed solution was
stirred for 24 hours at room temperature, then 366.7 g of a
colloidal silica dispersion Suncolloid MAST from NISSAN, 30% dry
matter in methanol, 6.3 g of aluminium acetylacetonate, 18.9 g of
methyl ethyl ketone, 450.4 g of methanol and 1.5 g of surfactant FC
430 were added thereto. The theoretical dry matter (TDM) of this
composition was of about 20% by weight.
[0244] Upper Layer Composition B3:
[0245] 2.43 g of phosphoric acid (purity: 99%) were dropped into a
solution containing 169.6 g of Glymo and 277.4 g of TEOS. During
hydrolysis, the temperature raised up to 45.degree. C. The
hydrolyzed solution was stirred for 24 hours at room temperature,
then 9.6 g of N-cyanoguanidine, 269.5 g of deionized water, 72.3 g
of 1-methoxypropan-2-ol marketed under the trade name DOWANOL
PM.RTM. by Dow Chemical and 0.8 g of surfactant EFKA.RTM. 3034
(Ciba Specialty Chemicals) were added thereto, so as to improve the
spreading capacity of such formulation. The theoretical dry matter
(TDM) of this composition was of about 26% by weight.
Remark: in comparative example 17, composition B3 was used as a
lower layer composition.
[0246] Upper Layer Composition B4 (Comparative Composition):
[0247] 2.45 g of phosphoric acid (purity: 99%) were dropped into a
solution containing 90.4 g of Glymo and 332.9 g of TEOS. During
hydrolysis, the temperature raised up to 45.degree. C. The
hydrolyzed solution was stirred for 24 hours at room temperature,
then 9.6 g of N-cyanoguanidine, 271.7 g of deionized water, 95.3 g
of 1-methoxypropan-2-ol marketed under the trade name DOWANOL
PM.RTM. by Dow Chemical and 0.8 g of surfactant EFKA.RTM. 3034
(Ciba Specialty Chemicals) were added thereto, so as to improve the
spreading capacity of such formulation. The theoretical dry matter
(TDM) of this composition was of about 20.8% by weight.
[0248] Upper Layer Composition B5:
[0249] 1.92 g of phosphoric acid (purity: 99%) were dropped into a
solution containing 102.4 g of Glymo and 249.6 g of TEOS. During
hydrolysis, the temperature raised up to 45.degree. C. The
hydrolyzed solution was stirred for 24 hours at room temperature,
then 5.6 g of N-cyanoguanidine, 219.2 g of deionized water, 220.5 g
of 1-methoxypropan-2-ol marketed under the trade name DOWANOL
PM.RTM. by Dow Chemical and 0.8 g of surfactant EFKA.RTM. 3034
(Ciba Specialty Chemicals) were added thereto, so as to improve the
spreading capacity of such formulation. The theoretical dry matter
(TDM) of this composition was of about 18% by weight.
[0250] c) Deposition Procedures for the Abrasion-Resistant
Bilayered Coating
[0251] Procedure 1
[0252] A substrate for an ophthalmic lens ORMA.RTM. (optionally
coated with a primer layer, example 15) was coated by being
dip-coated with a lower layer composition. The dewetting rate of
these lenses was adjusted in such a way that the deposited
thickness be of 3.5 .mu.m. The lower layer composition was then
polymerized in an oven for 3 h at 100.degree. C.
[0253] After such polymerization, the lens coated with the
abrasion-resistant lower layer did undergo a surface preparation
intermediate treatment aiming at activating the surface of the
abrasion-resistant lower layer so as to facilitate the anchoring of
the abrasion-resistant upper layer.
[0254] The lens was then coated by being dip-coated with an upper
layer composition, by adjusting the dewetting rate so as to obtain
a deposition of 1 .mu.m thick. Such upper layer composition was
then polymerized in an oven for 3 h at 100.degree. C.
[0255] Procedure 2
[0256] A substrate for an ophthalmic lens ORMA.RTM. was coated by
being dip coated with a lower layer composition. The dewetting rate
of these lenses was adjusted in such a way that the deposited
thickness be of 3.5 .mu.m. The lower layer composition was then
prepolymerized in an oven for 10 min at 90.degree. C.
[0257] The lens was then cooled for 15 minutes at room temperature
and was then directly coated by being dip-coated with an upper
layer composition by adjusting the dewetting rate so as to obtain a
deposition of 1 .mu.m thick.
[0258] This upper layer composition was then polymerized in an oven
for 3 h at 100.degree. C. thus also completing the polymerization
of the lower layer composition.
[0259] Procedure 3
[0260] The same as Procedure 2, except for the prepolymerization
step of the lower layer which was carried out for 15 min at
90.degree. C.
[0261] Procedure 4
[0262] The same as Procedure 2, except for the prepolymerization
step of the lower layer which was carried out for 5 min at
100.degree. C.
[0263] Procedure 5
[0264] The same as Procedure 2, except for the prepolymerization
step of the lower layer which was carried out for 10 min at
100.degree. C.
[0265] Procedure 6
[0266] The same as Procedure 2, except for the prepolymerization
step of the lower layer which was carried out at 100.degree. C. for
30 min, and the step of polymerization which was conducted at
100.degree. C. for 30 minutes.
[0267] Moreover, the lens dewetting rate was adjusted in such a way
that the lower layer composition deposited be 3 .mu.m thick and the
upper layer composition deposited be 1.5 .mu.m thick.
[0268] Procedure 7
[0269] The same as Procedure 6, except that prior to depositing the
lower layer composition, the substrate for the ophthalmic lens
ORMA.RTM. was coated by being dip coated with a monolayer of an
additional abrasion-resistant and/or scratch-resistant coating (the
dewetting rate of the lens being adjusted in such a way that the
deposited thickness be of 2.5 .mu.m), which was prepolymerized in
an oven for 30 min at 100.degree. C.
[0270] Moreover, the lens dewetting rate was adjusted in such a way
that the lower layer composition deposited be 2 .mu.m thick and the
upper layer composition deposited be 1.5 .mu.m thick.
[0271] Said additional monolayered abrasion-resistant and/or
scratch-resistant coating was formed from a composition obtained as
follows:
[0272] 77.6 g of hydrochloric acid 0.1N were dropped into a beaker
containing 339.2 g of Glymo. During hydrolysis, the temperature
raised up to 40-42.degree. C. The hydrolyzed solution was stirred
for 24 hours at room temperature, then 10.8 g of itaconic acid, 3.4
g of N-cyanoguanidine, 367.9 g of methanol and 1.2 g of surfactant
EFKA.RTM. 3034 (Ciba Specialty Chemicals) were added thereto. The
theoretical dry matter (TDM) of this composition was of about
31.35% by weight.
[0273] Procedure 8
[0274] The same as Procedure 2, except that prior to depositing the
lower layer composition, the substrate for the ophthalmic lens
ORMA.RTM. was coated by being dip coated with a 8 .mu.m-thick
impact-resistant primer layer, prepolymerized for 30 minutes at
90.degree. C.
[0275] The primer layer was formed from a composition prepared by
successively mixing 225.7 g of the polyurethane latex
Witcobond.RTM. 234, 774.4 g of demineralized water, 370.8 g of
colloidal fillers HX305 W1 (colloid of SnO.sub.2) marketed by CCIC,
and 3 g of surfactant Silwet L-77.RTM.. The theoretical dry matter
of this primer composition was of 20%.
[0276] Moreover, the lens dewetting rate was adjusted in such a way
that the lower layer composition deposited be 3 .mu.m thick and the
prepolymerization step of the lower layer was conducted at
90.degree. C. for 30 min.
[0277] Procedure 9
[0278] A substrate for an ophthalmic lens ORMA.RTM. was coated by
being dip coated with a lower layer composition. The dewetting rate
of these lenses was adjusted in such a way that the deposited
thickness be of 2.5 .mu.m. The lower layer composition was then
prepolymerized in an oven for 30 min at 100.degree. C.
[0279] The lens was then cooled for 15 minutes at room temperature
and was then directly coated by being dip coated with an upper
layer composition by adjusting the dewetting rate so as to obtain a
deposit thickness of 1.5 .mu.m. The upper layer composition was
then prepolymerized in an oven for 30 min at 90.degree. C.
[0280] The lens was cooled for 15 minutes at room temperature and
was then directly coated by being dip coated with an
abrasion-resistant and/or scratch-resistant coating additional
layer (the dewetting rate of the lens being adjusted in such a way
that the deposited thickness be of 1 .mu.m), such a deposition
being followed with a polymerisation final step of the whole, that
was conducted at 90.degree. C. for 30 minutes.
[0281] The additional layer of monolayered abrasion-resistant
and/or scratch-resistant coating was formed from a composition
obtained as follows:
[0282] 2.45 g of phosphoric acid (purity: 99%) were dropped into a
solution containing 90.4 g of Glymo and 332.9 g of TEOS. During
hydrolysis, the temperature raised up to 45.degree. C. The
hydrolyzed solution was stirred for 24 hours at room temperature,
then 9.6 g of N-cyanoguanidine, 271.7 g of deionized water, 95.3 g
of 1-methoxypropan-2-ol marketed under the trade name DOWANOL
PM.RTM. by Dow Chemical and 0.8 g of surfactant EFKA.RTM. 3034
(Ciba Specialty Chemicals) were added thereto, so as to improve the
spreading capacity of such formulation. The theoretical dry matter
(TDM) of this composition was of about 20.8% by weight.
[0283] Procedure 10:
[0284] The same as Procedure 8, except that the primer layer was
formed from a composition prepared by successively mixing 171.81 g
of the polyurethane latex Witcobond.RTM. 234, 201.8 g of
demineralized water, 196.98 g of colloidal silica fillers LUDOX
H540 (silica content of 40% by weight), 531.2 g of demineralized
water and 1.844 g of surfactant Silwet L-77.RTM.. The theoretical
dry matter of this primer composition was of 15%.
[0285] d) Surface Pre-Treatment Procedures of the
Abrasion-Resistant Lower Layer
[0286] Surface Preparation Using Soda
[0287] The lenses coated with the abrasion-resistant lower layer
were dipped into a 5% weight soda bath at a temperature of
50.degree. C. (except for tests 1 and 15 where the temperature was
of 40.degree. C.), provided with ultrasounds, for 1 minute. They
were then rinsed in demineralized water, and dried.
[0288] Surface Preparation Using Plasma
[0289] The lenses coated with the abrasion-resistant lower layer
did undergo an oxygen plasma treatment (power 1200 W for 4.5
minutes, gas flow rate O.sub.2: 200 mL/min, pressure 0.2 bar).
[0290] Surface Preparation Using Corona
[0291] The lenses coated with the abrasion-resistant lower layer
did undergo a corona discharge treatment (distance between glass
and electrode from 1 cm to 2 cm, treatment time 10 seconds, power
of the emitter 100 W).
2. Characterizations
[0292] To appreciate the properties of the coated glasses obtained
in the examples, the abrasion resistance was measured by means of
the value obtained in the BAYER ISTM test, the scratch resistance
using a steel wool test, and the abrasion-resistant coating
adhesion using the "cross-hatch test".
[0293] Obtaining a high value in the BAYER ISTM test is an
indication of a high level of abrasion resistance, whereas a low
value in the steel wool test is an indication of a high level of
scratch resistance.
[0294] The three tests employed are described hereunder.
[0295] a) Characterization of the Abrasion Resistance: BAYER ISTM
Test (Bayer Alumina)
[0296] The abrasion resistance was evaluated by determining the
BAYER ISTM values for substrates coated with the abrasion-resistant
coating of the invention or with a comparative abrasion-resistant
coating, for substrates coated with the abrasion-resistant coating
of the invention and with an antireflective coating (examples 1, 2,
4, 5), for substrates coated with a primer coating and with the
abrasion-resistant coating of the invention (examples 15, 19, 21,
22), for substrates coated with an additional abrasion-resistant
and/or scratch-resistant coating and with the abrasion-resistant
bilayered coating of the invention (example 18), or for substrates
coated with the abrasion-resistant bilayered coating of the
invention and with a supplementary abrasion-resistant and/or
scratch-resistant coating layer (example 20).
[0297] This BAYER value was determined based on ASTM F735-81
standard, with following modifications: 300 cycles were effected
rather than 200 and the abrasive powder was not sand but alumina
(Al.sub.2O.sub.3) ZF 152412 provided by Ceramic Grains (formerly
Norton Materials, New Bond Street, PO Box 15137 Worcester, Mass.
01615-00137).
[0298] This test consists in simultaneously stirring a sample glass
and a standard glass with a determinated reciprocating motion in a
vessel containing the abrasive powder (approximately 500 g) having
a defined particle size at a frequency of 100 cycles/minute for 3
minutes. Diffusion measurement H "before/after" of the sample glass
was compared with that of a standard glass, especially a
CR-39.RTM.-based bare glass, for which the BAYER value ISTM was
fixed to 1. The BAYER value ISTM was calculated as R.dbd.H
standard/H sample glass.
[0299] Diffusion measurement was conducted by using a Hazeguard
system model XL-211 made by Pacific Scientific.
[0300] The BAYER ISTM value was estimated to be good when R was
higher than or equal to 3 and lower than 4.5, and excellent when R
was equal to or higher than 4.5
[0301] b) Hardness Characterization--Scratch Resistance (Manual
Test)
[0302] The scratch resistance was measured by using the steel wool
test which did consist in performing 5 forward and back motions by
rubbing with the hand along 4-5 cm the face of a glass coated
according to the invention with a steel wool, in the fiber
direction, while applying a constant pressure on the steel wool
during this operation (5 k g forward, 2.5 k g back). A piece of
about 3 cm.times.3 cm of extra fine steel wool STARWAX (grade 000)
folded upon itself was used.
[0303] The glass was then wiped with a dry cloth, rinsed with
alcohol, then visually examined. A notation was given according to
the following graduation (3 scores: 1, 3 or 5):
[0304] 1: there is no visible scratch observed or barely visible
scratch on the glass (from 1 to 10 scratches)
[0305] 3: relatively scratched glass (from 11 to 50 scratches)
[0306] 5: strongly scratched glass (more than 50 scratches)
[0307] c) Characterization of the Abrasion-Resistant Coating
Adhesion ("Cross-Hatch Test")
[0308] The adhesion test was made based on the ASTM D3359-93
standard and resulted in a qualitative ordering ranging from 0 to
5, 0 being the best result.
[0309] It did consist in notching the abrasion-resistant bilayered
coating of the invention deposited onto a substrate using a
precision knife, according to a cross-hatched pattern of notching
lines, in applying an adhesive tape onto the thus cross-hatched
coating and in trying to tear it out with the same. The results
were considered to be good at level zero if the edges where the
notches were made remained perfectly smooth and if no square,
amongst the ones they did delimit, came off.
[0310] This adhesion test may also be conducted after the lens
substrate coated with the abrasion-resistant bilayered coating of
the invention has been dipped into a bath of boiling hot water for
30 minutes.
3. Results
[0311] The performances of both abrasion and scratch resistance for
the various optical articles prepared are given in Table 1. The
results of the comparative tests are in bold.
TABLE-US-00002 TABLE 1 Example 1 2 3 4 5 6 7 8 9 10 11 12 Lower
layer A A A A1 A2 A3 A A1 A A4 A A composition Intermediate S P C S
S S S S S S -- -- surface preparation Upper layer B B B B B B B1 B1
B2 B2 B B composition AR coating yes yes no yes yes no no no no no
no no Ri 4.7 4.7 4.7 +.infin. +.infin. 4.6 4.7 +.infin. 4.7
+.infin. 4.7 4.7 Rs 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05
+.infin. +.infin. 1.05 1.05 Deposition 1 1 1 1 1 1 1 1 1 1 2 3
procedure of the abrasion- resistant coating Bayer ISTM 19.2 12.6
9.8 15.8 17.1 8.1 7.6 9.1 6.4 5.2 16.5 13.5 Test Without AR coating
Steel wool 1 1 1 1 1 1 1 3 1 3 1 1 test Without AR coating Bayer
ISTM 11.2 4.8 6.1 5.8 Test with AR coating Example 13 14 15* 16 17
18 19* 20 21* 22* Lower layer A A A A6 B3 A7 A7 A5 A7 A8
composition Intermediate -- -- S -- -- -- -- -- -- -- surface
preparation Upper layer B B B A5 B4 B5 B5 B3 B5 B5 composition AR
coating no no no no no no no no no no Ri 4.7 4.7 4.7 +.infin. 1.5
4.6 4.6 4 4.6 4.5 Rs 1.05 1.05 1.05 4 0.67 1 1 1.5 1 1 Deposition 4
5 1 6 6 7 8 9 10 8 procedure of the abrasion- resistant coating
Bayer ISTM 18.2 14.2 19.4 0.9 6.6 12.5 12.2 11.7 12.7 9.7 Test
Without AR coating Steel wool 1 1 1 3 3 3 test Without AR coating
Bayer ISTM 10 Test with AR coating S = soda, P = plasma, C =
corona. AR = antireflective. *Substrate pre-coated with an
impact-resistant primer layer.
[0312] The abrasion-resistant coatings according to the invention
offer much higher performances than those that would have been
obtained if a monolayered coating had been used. After having
deposited an antireflective coating onto the abrasion-resistant
coating, the performances were also much higher than those that
would have been obtained if a monolayered coating had been
used.
[0313] Examples 1 to 3 show that an intermediate surface
preparation using soda is preferred as compared to a plasma or
corona discharge treatment.
[0314] Compositions A and B, which contained a GLYMO and TEOS
mixture and which used the itaconic acid/N-cyanoguanidine catalyst
system are more efficient than compositions A3 and B1 which used
the Al(acac).sub.3 catalyst.
[0315] The results of comparative examples 9 and 10, which used
colloidal silica rather than TEOS, are much poorer as regards the
abrasion- and scratch resistance. In the same way, the articles of
comparative examples 16 and 17, which did not present Rs and/or Ri
ratios in accordance with those of the invention, have a poor
abrasion resistance.
[0316] The conducted adhesion tests (cross-hatch test) did reveal a
very strong intercoat adhesion (score: zero), even after the
glasses remained dipped for 30 minutes in water at 100.degree. C.,
and this result was obtained whether the first alternative of the
method the invention was carried out (examples 1 to 8 and 15, with
the intermediate surface preparation) or the second alternative of
the method of the invention (examples 11 to 14, with no
intermediate surface preparation). In the latter case, the adhesion
between the two layers of the abrasion-resistant coating is
obtained by prepolymerizing the lower layer.
[0317] Introducing a primer coating did not change the abrasion and
scratch resistance properties of the optical articles (results from
examples 1, 15, 19, 21 and 22).
[0318] Introducing an additional abrasion-resistant coating between
the substrate and the bilayered coating of the invention also leads
to articles having a very high abrasion resistance (example 18), as
well as introducing a supplementary abrasion-resistant and/or
scratch-resistant coating layer in contact with the upper layer of
the bilayered coating of the invention (example 20).
[0319] Examples 19, 21 and 22 illustrate the invention for a stack
comprising in a colloid filled primer (SiO.sub.2 for example 21 and
SnO.sub.2 for examples 19 and 22) and a lower layer of the
bilayered coating itself filled with colloid (example 22).
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