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: $\mathrm{Rs}=\frac{\begin{array}{c}\mathrm{theoretical}\mathrm{dry}\mathrm{matter}\mathrm{weight}\mathrm{of}\\ \mathrm{compounds}I\mathrm{in}\mathrm{the}\mathrm{upper}\mathrm{layer}\mathrm{composition}\end{array}}{\begin{array}{c}\mathrm{theoretical}\mathrm{dry}\mathrm{matter}\mathrm{weight}\mathrm{of}\\ \mathrm{compounds}\mathrm{II}\mathrm{in}\mathrm{the}\mathrm{upper}\mathrm{layer}\mathrm{composition}\end{array}}$
said lower layer composition comprising at least one organosilane, or a hydrolyzate thereof, of formula R.sub.nY.sub.mSi(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: $\mathrm{Ri}=\frac{\begin{array}{c}\mathrm{theoretical}\mathrm{dry}\mathrm{matter}\mathrm{weight}\mathrm{of}\\ \mathrm{compounds}\mathrm{III}\mathrm{in}\mathrm{the}\mathrm{lower}\mathrm{layer}\mathrm{composition}\end{array}}{\begin{array}{c}\mathrm{theoretical}\mathrm{dry}\mathrm{matter}\mathrm{extract}\mathrm{of}\\ \mathrm{compounds}\mathrm{IV}\mathrm{in}\mathrm{the}\mathrm{lower}\mathrm{layer}\mathrm{composition}\end{array}}$
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.

Claims

1. An optical article comprising a substrate having at least one main surface coated with an abrasion- and scratch-resistant coating, the coating comprised of, starting from the substrate, a lower layer and an upper layer that 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: the 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) wherein the R groups are individually monovalent organic groups that are bound to silicon through a carbon atom and that contain at least one epoxy function, the X groups are individually 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) wherein M represents a metal or a metalloid, the Z groups are individually hydrolyzable groups and x, equal to or higher than 4, is a metal or metalloid M valence, the ratio: $\mathrm{Rs}=\frac{\begin{array}{c}\mathrm{theoretical}\mathrm{dry}\mathrm{matter}\mathrm{weight}\mathrm{of}\\ \mathrm{compounds}I\mathrm{in}\mathrm{the}\mathrm{upper}\mathrm{layer}\mathrm{composition}\end{array}}{\begin{array}{c}\mathrm{theoretical}\mathrm{dry}\mathrm{matter}\mathrm{weight}\mathrm{of}\\ \mathrm{compounds}\mathrm{II}\mathrm{in}\mathrm{the}\mathrm{upper}\mathrm{layer}\mathrm{composition}\end{array}}$ being lower than or equal to 2.3; and the lower layer composition comprises: at least one organosilane compound, or a hydrolyzate thereof, of formula:
R.sub.nY.sub.mSi(X).sub.4-n-m(III) wherein the R groups are individually monovalent organic groups that are bound to silicon through a carbon atom and that contain at least one epoxy function, the X groups are individually 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, wherein the lower and/or upper layer compositions comprise a catalytic system composed of aluminum acetylacetonate or composed of a mixture of itaconic acid and N-cyanoguanidine.

2. The article of claim 1, wherein compound (II) is of formula Si(Z).sub.4, wherein the Z groups are individually hydrolyzable groups.

3. The article of claim 1, wherein the lower layer composition further comprises at least one compound, or a hydrolyzate thereof, of formula:
M(Z)y(IV) wherein M represents a metal or a metalloid, the Z groups are individually hydrolyzable groups and y is higher than or equal to 4 and the metal or metalloid M valence, the ratio: $\mathrm{Ri}=\frac{\begin{array}{c}\mathrm{theoretical}\mathrm{dry}\mathrm{matter}\mathrm{weight}\mathrm{of}\\ \mathrm{compounds}\mathrm{III}\mathrm{in}\mathrm{the}\mathrm{lower}\mathrm{layer}\mathrm{composition}\end{array}}{\begin{array}{c}\mathrm{theoretical}\mathrm{dry}\mathrm{matter}\mathrm{weight}\mathrm{of}\\ \mathrm{compounds}\mathrm{IV}\mathrm{in}\mathrm{the}\mathrm{lower}\mathrm{layer}\mathrm{composition}\end{array}}$ being higher than 2.3.

4. The article of claim 3, wherein compound (IV) is of formula Si(Z).sub.4, wherein the Z groups are individually hydrolyzable groups.

5. The article of claim 3, wherein Ri is higher than or equal to 3.5.

6. The article of claim 3, wherein compound III is -glycidoxypropyl trimethoxysilane, compound IV is tetraethoxysilane and Rs ranges from 1 to 1.5.

7. The article of claim 1, wherein Rs is lower than or equal to 2.0 and higher than or equal to 0.85.

8. The article of claim 1, wherein the theoretical dry matter weight of compound I represents from 30 to 60% of the upper layer composition dry matter weight.

9. The article of claim 1, wherein the theoretical dry matter weight of compound III represents more than 40% of the lower layer composition dry matter weight.

10. The article of claim 1, wherein the theoretical dry matter weight of compound IV represents less than 30% of the lower layer composition dry matter weight.

11. The article of claim 1, wherein the thickness of the abrasion- and scratch-resistant coating does vary from 1 to 15 m.

12. The article of claim 1, wherein the thickness ratio of the lower layer to the upper layer is higher than or equal to 1.5.

13. The article of claim 1, wherein the Y or Y groups are independently 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/or perfluoro alkoxy[(poly)alkylenoxy]alkyl groups.

14. The article of claim 1, wherein the R or R groups are selected, independently from each other, from groups of formulas V and VI: ##STR00003## wherein R.sup.2 is an alkyl group or a hydrogen atom, a and c are integers ranging from 1 to 6, and b is 0, 1 or 2.

15. The article of claim 14, wherein the R or R groups are independently -glycidoxypropyl groups, -(3,4-epoxycyclohexyl)ethyl and/or -glycidoxyethoxypropyl groups.

16. The article of claim 1, wherein compounds of formula I and/or III are, independently compounds of formulas VII and ##STR00004## wherein R.sup.1 is an alkyl moiety having from 1 to 6 carbon atoms, a and c are integers ranging from 1 to 6, and b is 0, 1 or 2.

17. The article of claim 1, wherein compounds of formula II and/or IV are independently a tetraalkoxysilane.

18. The article of claim 1, wherein the lower and/or upper layer compositions comprise at least one condensation catalyst and/or at least one curing catalyst.

19. The article of claim 18, wherein the condensation catalyst comprises an acid or anhydride of polyfunctional saturated or unsaturated acids.

20. The article of claim 1, 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.

21. The article of claim 1, further defined as comprising, starting from the substrate, an impact-resistant primer layer coated with the abrasion- and scratch-resistant coating.

22. The article of claim 1, further comprising a supplementary layer of an abrasion-resistant and/or scratch-resistant coating contacting the upper layer, the abrasion-resistant and/or scratch-resistant supplementary layer being a layer of cured supplementary abrasion-resistant and/or scratch-resistant layer composition, the supplementary layer composition comprising: at least one organosilane compound, or a hydrolyzate thereof, of formula:
R.sub.nY.sub.mSi(X).sub.4-n-m(IX) wherein the R groups are individually monovalent organic groups that are bound to silicon through a carbon atom and that contain at least one epoxy function, the X groups are individually 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) wherein M represents a metal or a metalloid, the Z groups are individually hydrolyzable groups and z, equal to or higher than 4, is a metal or metalloid M valence, the ratio: $\mathrm{Rss}=\frac{\begin{array}{c}\mathrm{theoretical}\mathrm{dry}\mathrm{matter}\mathrm{weight}\mathrm{of}\\ \mathrm{compounds}\mathrm{IX}\mathrm{in}\mathrm{the}\mathrm{supplementary}\mathrm{layer}\mathrm{composition}\end{array}}{\begin{array}{c}\mathrm{theoretical}\mathrm{dry}\mathrm{matter}\mathrm{weight}\mathrm{of}\\ \mathrm{compounds}X\mathrm{in}\mathrm{the}\mathrm{supplementary}\mathrm{layer}\mathrm{composition}\end{array}}$ being lower than or equal to 2.3 and strictly lower than ratio Rs, the supplementary theoretical dry matter weight of compounds X comprising 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.

23. The article of claim 22, wherein z is from 4 to 6.

24. The article of claim 22, wherein Rss is lower than or equal to 2.0.

25. The article of claim 24, wherein Rss is higher than or equal to 0.85.

26. The article of claim 1, further defined as an ophthalmic lens.

27. 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 claim 1; c) at least partially curing the lower layer composition using a thermal process; d) depositing onto the layer resulting from the previous step a layer of an upper layer composition as defined in claim 1; e) curing the upper layer composition using a thermal process; and 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.

28. The method of 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 C., for 30 minutes to 4 hours.

29. The method of claim 27, 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.

30. 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 C. for 1 to 30 minutes and wherein the surface of the article resulting from step c) does not undergo before step d) any surface preparation treatment.

31. The method of claim 30, wherein the lower layer composition is partially cured using a thermal process during step c) at a temperature ranging from 80 to 120 C., for 1 to 30 minutes.

32. The article of claim 1, wherein the lower and/or upper layer compositions comprise a catalytic system composed of a mixture of itaconic acid and N-cyanoguanidine.

33. An optical article comprising a substrate having at least one main surface coated with an abrasion- and scratch-resistant coating, the abrasion- and scratch-resistant coating comprised of, starting from the substrate, a lower layer and an upper layer that 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: the 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) wherein the R groups are individually monovalent organic groups that are bound to silicon through a carbon atom and that contain at least one epoxy function, the X groups are individually 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) wherein M represents a metal or a metalloid, the Z groups are individually hydrolyzable groups and x, equal to or higher than 4, is a metal or metalloid M valence, the ratio: $\mathrm{Rs}=\frac{\begin{array}{c}\mathrm{theoretical}\mathrm{dry}\mathrm{matter}\mathrm{weight}\mathrm{of}\\ \mathrm{compounds}I\mathrm{in}\mathrm{the}\mathrm{upper}\mathrm{layer}\mathrm{composition}\end{array}}{\begin{array}{c}\mathrm{theoretical}\mathrm{dry}\mathrm{matter}\mathrm{weight}\mathrm{of}\\ \mathrm{compounds}\mathrm{II}\mathrm{in}\mathrm{the}\mathrm{upper}\mathrm{layer}\mathrm{composition}\end{array}}$ being lower than or equal to 2.3; and the lower layer composition comprises: at least one organosilane compound, or a hydrolyzate thereof, of formula:
R.sub.nY.sub.mSi(X).sub.4-n-m(III) wherein the R groups are individually monovalent organic groups that are bound to silicon through a carbon atom and that contain at least one epoxy function, the X groups are individually 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, wherein the optical article further comprises an antireflection coating adhered to the upper layer composition.

34. The optical article of claim 33, wherein the lower and/or upper layer compositions comprise a catalytic system composed of aluminum acetylacetonate or composed of a mixture of itaconic acid and N-cyanoguanidine.

Description

EXAMPLES

1. General Procedures

(1) The optical articles used in examples 1-8 and 11-15 comprise an ORMA 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: optionally a 1 m-thick layer of a polyurethane type impact-resistant primer based on Witcobond 234 optionally filled (examples 15, 19, 21, 22); optionally a 2.5 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; 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; optionally a supplementary abrasion-resistant and/or scratch-resistant coating layer (example 20); and 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).

(2) 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.

(3) a) Preparation of the Abrasion-Resistant Lower Layer Compositions

(4) Lower Layer Composition A:

(5) 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 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.

(6) Lower Layer Composition A1:

(7) 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 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.

(8) Lower Layer Composition A2:

(9) 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 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.

(10) Lower Layer Composition A3:

(11) 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 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.

(12) Lower Layer Composition A4 (Comparative Composition):

(13) 64 g of hydrochloric acid 0.1N were dropped into 183 g of Glymo under stirring. During hydrolysis, the temperature raised up to 46 C. After 30 minutes, the hydrolyzate temperature had decreased to 28 C., and 91 g of DMDES (dimethyl diethoxysilane) were then dropped. This addition is slightly exothermic (29 C.).

(14) 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.

(15) Lower Layer Composition A5:

(16) 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 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 by Dow Chemical and 0.8 g of surfactant EFKA 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.

(17) Remark: in comparative example 16, composition A5 was used as an upper layer composition.

(18) Lower Layer Composition A6:

(19) 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 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 3034 (Ciba Specialty Chemicals) were added thereto. The theoretical dry matter (TDM) of this composition was of about 31.35% by weight.

(20) Lower Layer Composition A7:

(21) 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 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 3034 (Ciba Specialty Chemicals) were added thereto. The theoretical dry matter (TDM) of this composition was of about 30% by weight.

(22) Lower Layer Composition A8:

(23) 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.

(24) TABLE-US-00001 Components gram Glymo 174.88 HCl 0.1N 71.99 TiO.sub.2/SiO.sub.2/ZrO.sub.2 composite 609.61 particle colloid (firm CCIC) Al(Acac).sub.3 9.08 Methyl ethyl ketone 27.23 Methanol 9.36 EFKA 3034 1.50

(25) b) Preparation of the Abrasion-Resistant Upper Layer Compositions

(26) Upper Layer Composition B:

(27) 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 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.

(28) Upper Layer Composition B1:

(29) 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 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.

(30) Upper Layer Composition B2 (Comparative Composition):

(31) 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 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.

(32) Upper Layer Composition B3:

(33) 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 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 by Dow Chemical and 0.8 g of surfactant EFKA 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.

(34) Remark: in comparative example 17, composition B3 was used as a lower layer composition.

(35) Upper Layer Composition B4 (Comparative Composition):

(36) 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 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 by Dow Chemical and 0.8 g of surfactant EFKA 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.

(37) Upper Layer Composition B5:

(38) 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 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 by Dow Chemical and 0.8 g of surfactant EFKA 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.

(39) c) Deposition Procedures for the Abrasion-Resistant Bilayered Coating

(40) Procedure 1

(41) A substrate for an ophthalmic lens ORMA (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 m. The lower layer composition was then polymerized in an oven for 3 h at 100 C.

(42) 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.

(43) 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 m thick. Such upper layer composition was then polymerized in an oven for 3 h at 100 C.

(44) Procedure 2

(45) A substrate for an ophthalmic lens ORMA 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 m. The lower layer composition was then prepolymerized in an oven for 10 min at 90 C.

(46) 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 m thick.

(47) This upper layer composition was then polymerized in an oven for 3 h at 100 C. thus also completing the polymerization of the lower layer composition.

(48) Procedure 3

(49) The same as Procedure 2, except for the prepolymerization step of the lower layer which was carried out for 15 min at 90 C.

(50) Procedure 4

(51) The same as Procedure 2, except for the prepolymerization step of the lower layer which was carried out for 5 min at 100 C.

(52) Procedure 5

(53) The same as Procedure 2, except for the prepolymerization step of the lower layer which was carried out for 10 min at 100 C.

(54) Procedure 6

(55) The same as Procedure 2, except for the prepolymerization step of the lower layer which was carried out at 100 C. for 30 min, and the step of polymerization which was conducted at 100 C. for 30 minutes.

(56) Moreover, the lens dewetting rate was adjusted in such a way that the lower layer composition deposited be 3 m thick and the upper layer composition deposited be 1.5 m thick.

(57) Procedure 7

(58) The same as Procedure 6, except that prior to depositing the lower layer composition, the substrate for the ophthalmic lens ORMA 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 m), which was prepolymerized in an oven for 30 min at 100 C.

(59) Moreover, the lens dewetting rate was adjusted in such a way that the lower layer composition deposited be 2 m thick and the upper layer composition deposited be 1.5 m thick.

(60) Said additional monolayered abrasion-resistant and/or scratch-resistant coating was formed from a composition obtained as follows:

(61) 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 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 3034 (Ciba Specialty Chemicals) were added thereto. The theoretical dry matter (TDM) of this composition was of about 31.35% by weight.

(62) Procedure 8

(63) The same as Procedure 2, except that prior to depositing the lower layer composition, the substrate for the ophthalmic lens ORMA was coated by being dip coated with a 8 m-thick impact-resistant primer layer, prepolymerized for 30 minutes at 90 C.

(64) The primer layer was formed from a composition prepared by successively mixing 225.7 g of the polyurethane latex Witcobond 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. The theoretical dry matter of this primer composition was of 20%.

(65) Moreover, the lens dewetting rate was adjusted in such a way that the lower layer composition deposited be 3 m thick and the prepolymerization step of the lower layer was conducted at 90 C. for 30 min.

(66) Procedure 9

(67) A substrate for an ophthalmic lens ORMA 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 m. The lower layer composition was then prepolymerized in an oven for 30 min at 100 C.

(68) 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 m. The upper layer composition was then prepolymerized in an oven for 30 min at 90 C.

(69) 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 m), such a deposition being followed with a polymerisation final step of the whole, that was conducted at 90 C. for 30 minutes.

(70) The additional layer of monolayered abrasion-resistant and/or scratch-resistant coating was formed from a composition obtained as follows:

(71) 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 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 by Dow Chemical and 0.8 g of surfactant EFKA 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.

(72) Procedure 10:

(73) 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 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. The theoretical dry matter of this primer composition was of 15%.

(74) d) Surface Pre-Treatment Procedures of the Abrasion-Resistant Lower Layer

(75) Surface Preparation Using Soda

(76) The lenses coated with the abrasion-resistant lower layer were dipped into a 5% weight soda bath at a temperature of 50 C. (except for tests 1 and 15 where the temperature was of 40 C.), provided with ultrasounds, for 1 minute. They were then rinsed in demineralized water, and dried.

(77) Surface Preparation Using Plasma

(78) 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).

(79) Surface Preparation Using Corona

(80) 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 V.

2. Characterizations

(81) 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.

(82) 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.

(83) The three tests employed are described hereunder.

(84) a) Characterization of the Abrasion Resistance: BAYER ISTM Test (Bayer Alumina)

(85) 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).

(86) 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).

(87) 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-based bare glass, for which the BAYER value ISTM was fixed to 1. The BAYER value ISTM was calculated as RH standard/H sample glass.

(88) Diffusion measurement was conducted by using a Hazeguard system model XL-211 made by Pacific Scientific.

(89) 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.

(90) b) Hardness CharacterizationScratch Resistance (Manual Test)

(91) 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 cm3 cm of extra fine steel wool STARWAX (grade 000) folded upon itself was used.

(92) 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).

(93) 1: there is no visible scratch observed or barely visible scratch on the glass (from 1 to 10 scratches)

(94) 3: relatively scratched glass (from 11 to 50 scratches)

(95) 5: strongly scratched glass (more than 50 scratches)

(96) c) Characterization of the Abrasion-Resistant Coating Adhesion (Cross-Hatch Test)

(97) 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.

(98) 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.

(99) 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

(100) 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.

(101) 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 + + 4.6 4.7 + 4.7 + 4.7 4.7 Rs 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 + + 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 + 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.

(102) 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.

(103) Examples 1 to 3 show that an intermediate surface preparation using soda is preferred as compared to a plasma or corona discharge treatment.

(104) 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.

(105) 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.

(106) 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 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.

(107) 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).

(108) 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).

(109) 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).