Item having improved thermomechanical properties, comprising an organic-inorganic layer

Abstract

The invention relates to an item comprising a substrate having at least one main surface coated with a multilayer interferential coating comprising at least one layer with a refractive index higher than 1.65 and at least one layer with a refractive index lower than, or equal to, 1.65, at least one of the layers of the interferential coating being an organic-inorganic layer that has been deposited in a vacuum environment and has a thickness of at least 30 nm, said interferential coating having a thickness of at least 450 nm and/or at least 8 layers.

Claims

1. An article comprising a substrate having at least one main surface coated with a multilayer interference coating comprising at least one layer having a refractive index higher than 1.65 and at least one layer having a refractive index lower than or equal to 1.65 comprising SiO.sub.2, at least one of the layers of the multilayer interference coating being an organic-inorganic layer obtained by deposition under vacuum of at least one organosilicon compound and that has a physical thickness larger than or equal to 250 nm, said multilayer interference coating having a number of layers higher than or equal to 9; wherein said organic-inorganic layer does not comprise any metal oxide; wherein the article comprises the following components stacked in the following order: said substrate, a first layer having a refractive index higher than 1.65 comprising ZrO.sub.2, said organic-inorganic layer, in direct contact with a layer comprising a silicon oxide and having a physical thickness less than or equal to 15 nm, in direct contact with a second layer having a refractive index higher than 1.65 containing at least one metal oxide, wherein the organosilicon compound is chosen from octamethylcyclotetrasiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane, decamethyltetrasiloxane, decamethyl cyclopentasiloxane, dodecamethylpentasiloxane, and hexamethyldisiloxane, and wherein the substrate is an organic substrate.

2. The article as claimed in claim 1, wherein the organic-inorganic layer comprises atoms of carbon, of oxygen and of a metal or metalloid.

3. The article as claimed in claim 1, wherein the organic-inorganic layer is deposited under the assistance of a source of ions.

4. The article as claimed in claim 1, wherein the organic-inorganic layer is a layer A having has a refractive index lower than or equal to 1.65.

5. The article as claimed in claim 1, wherein said organic-inorganic layer does not comprise any purely inorganic compound.

6. The article as claimed in claim 1, wherein the multilayer interference coating has a physical thickness larger than or equal to 450 nm.

7. The article as claimed in claim 1, wherein the multilayer interference coating has a physical thickness larger than 1 μm.

8. The article as claimed in claim 1, wherein said organic-inorganic layer has a physical thickness larger than or equal to 300 nm.

9. The article as claimed in claim 1, wherein the multilayer interference coating comprises a second organic-inorganic layer.

10. The article as claimed in claim 1, wherein the multilayer interference coating is a selective optical filter and/or an antireflection coating.

11. The article as claimed in claim 1, wherein the organic-inorganic layer is deposited under ion bombardment achieved by means of an ion gun.

12. The article as claimed in claim 1, wherein the multilayer interference coating is a selective optical filter that at least partially blocks blue light having a wavelength ranging from 400 to 500 nm.

13. The article as claimed in claim 1, wherein said organic-inorganic layer contains more than 90% by weight of organosilicon compounds with respect to the weight of the layer.

14. The article as claimed in claim 1, wherein said organic-inorganic layer contains 100% by weight of organosilicon compounds with respect to the weight of the layer.

15. The article as claimed in claim 1, wherein the multilayer interference coating comprises at least one purely inorganic layer.

16. The article as claimed in claim 1, wherein said organic-inorganic layer contains more than 80% by weight of organosilicon compounds with respect to the weight of the layer.

17. The article as claimed in claim 1, wherein the multilayer interference coating has a number of layers higher than or equal to 10.

18. The article as claimed in claim 1, wherein said second layer having a refractive index higher than 1.65 comprises ZrO.sub.2.

19. The article as claimed in claim 18, wherein the organosilicon compound is decamethyltetrasiloxane.

Description

DETAILED DESCRIPTION

(1) The invention is illustrated in a nonlimiting way by the following examples.

Examples

(2) 1. General Procedures

(3) The articles employed in the examples comprise an Orma® Essilor lens substrate with a diameter of 65 mm, with a power of −2.00 diopters and with a center thickness of 1.2 mm, coated on its concave face with the impact-resistant primer coating and with the scratch-resistant and abrasion-resistant coating (hard coat), which are disclosed in the experimental section of the application WO 2010/109154, and an antireflection interference coating comprising a layer A according to the invention.

(4) The vacuum deposition reactor is a Leybold LAB1100+ device equipped with an electron gun for the evaporation of the precursor materials, with a thermal evaporator, with a KRI EH 1000 F ion gun (from Kaufman & Robinson Inc.), for the preliminary phase of preparation of the surface of the substrate by argon ions (IPC) and also for the deposition of the layers under ion bombardment (IAD), and with a system for the introduction of liquid, which system is used when the organosilicon precursor compound in particular of the layer A is a liquid under standard temperature and pressure conditions (case of decamethyltetrasiloxane). This system comprises a tank containing the liquid precursor compound of the layer in question, resistance heaters for heating the tank, tubes connecting the tank of liquid precursor to the vacuum deposition device and a vapor flowmeter from MKS (MKS1150C), brought to a temperature of 30-120° C. during its use, depending on the flow rate of vaporized decamethyltetrasiloxane, which preferably varies from 0.01 to 0.8 g/min (1 to 50 sccm) (the temperature is 120° C. for a flow rate of 0.3 g/min (20 sccm) of decamethyltetrasiloxane).

(5) The decamethyltetrasiloxane vapor exits from a copper tube inside the machine, at a distance of about 30 cm from the ion gun. Flows of oxygen and optionally of argon are introduced into the ion gun. Preferably, neither argon nor any other rare gas is introduced into the ion gun.

(6) The layers A according to the invention are formed by vacuum evaporation assisted by a beam of oxygen and optionally argon ions during the deposition (evaporation source: electron gun) of decamethyltetrasiloxane, supplied by Sigma-Aldrich.

(7) Unless otherwise indicated, the thicknesses mentioned in the present patent application are physical thicknesses. Several samples of each glass were prepared.

(8) 2. Procedures

(9) The process for the preparation of the optical articles according to the invention comprises the introduction of the substrate, coated with the primer coating and with the abrasion-resistant coating which are defined above, into the vacuum deposition chamber; the preheating of the tank, the pipes and the vapor flowmeter to the chosen temperature (˜15 min), a primary pumping stage, then a secondary pumping stage for 400 seconds making it possible to obtain a high vacuum (˜2×10.sup.−5 mbar, pressure read from a Bayard-Alpert gauge); a stage of activation of the surface of the substrate by a beam of argon ions (IPC: 1 minute, 100 V, 1 A, the ion gun remaining in operation at the end of this step), then the deposition by evaporation of an antireflection coating comprising at least one layer A.

(10) Deposition of a layer A according to the invention: The ion gun having been started with argon, oxygen is added to the ion gun with a programmed flow rate, the desired anode current (3 A) is programmed and the argon flow is optionally halted, depending on the deposition conditions desired. Generally, the process according to the invention is carried out with oxygen (flow rate of O.sub.2 in the ion gun level with the ion source: 20 sccm), in the absence of rare gas (no argon flow level with the ion source). The decamethyltetrasiloxane is introduced into the deposition chamber in gaseous form (injection flow rate: 20 sccm). The supply of this compound is stopped once the desired thickness has been obtained, then the ion gun is turned off.

(11) The other metal-oxide layers (containing no organosilicon compound) were deposited conventionally by vacuum evaporation of the right metal oxide (zirconium oxide, SiO.sub.2 etc.), without ion assistance.

(12) The thickness of the layers deposited was controlled in real-time by means of a quartz microbalance, the rate of deposition being modified, if need be, by adjusting the current of the electron gun. Once the desired thickness is obtained, the shutter or shutters were closed, the ion and electron gun or guns were switched off and the gas flows (oxygen, optionally argon and decamethyltetrasiloxane vapors) were halted.

(13) A final venting step was carried out once the deposition of the stack had finished.

(14) A plurality of comparative examples were prepared, the one or more layers A according to the invention being replaced with layers of SiO.sub.2. Thus, the stack of comparative example 1 differs from the stack of examples 1 to 3 in that the organosilicon compounds have been removed from the layers of the antireflection coating and replaced with silica, and the stack of comparative example 4 differs from the stack of the example 4 in that the organosilicon compounds have been removed from the layers of the antireflection coating and replaced with silica.

(15) The articles of examples 1-4 and of the comparative examples are selective optical filters for filtering blue light. The interference coating used in examples 1-3 and comparative example 1 is a stack of large thickness (1210.5 nm) comprising 5 layers having a large thickness (>100 nm). The interference coating used in example 4 and comparative example 4 is a stack of smaller thickness (510 nm) comprising a high number of layers (8).

(16) 3. Characterizations

(17) The critical temperature of the article is measured 24 hours and/or one week after its preparation, in the way indicated in the application WO 2008/001011.

(18) Unless otherwise indicated, the refractive indices to which reference is made in the present invention are expressed for a wavelength of 632.8 nm and were measured by ellipsometer at a temperature of 20-25° C.

(19) The bending resistance test, described in patent application WO 2013/098531, allows the capacity of an article having a curvature to undergo a mechanical deformation to be evaluated. The result of the test, which was carried out one month after production of the eyeglasses, is the critical deformation D in mm that the eyeglass can undergo before cracks appear. The higher the value of the deformation, the better the resistance to applied mechanical deformation.

(20) The adhesion properties of the whole of the interference coating to the substrate were verified on the convex face of the lens by means of the test commonly referred to in French as the “n×10 coups” test (i.e. the “n×10 rubs” test) following the procedure described in international patent applications WO 2010/109154 and WO 99/49097 (N.B. in the latter this test is referred to as the “n 10 blow” test), using a number of cycles equal to 13. The test consists in noting the number of cycles that the lens was able to be subjected to before the appearance of a defect. Therefore, the higher the value obtained in the n×10 rubs test, the better the adhesion of the interference coating to the substrate.

(21) The abrasion resistance of the article was evaluated by determining Bayer ASTM (Bayer sand) values for substrates coated with the antireflection coating, using the methods described in patent application WO 2008/001011 (standard ASTM F 735.81). The higher the value obtained in the Bayer test, the higher the resistance to abrasion. Thus, the Bayer ASTM (Bayer sand) value was deemed to be good when it was higher than or equal to 3.4 and lower than 4.5 and excellent for values of 4.5 or more.

(22) Hardness, or scratch resistance, was evaluated by virtue of the test referred to in French as the “paille de fer (pdf manuel, ou test à la laine d'acier)” test i.e. the “manual steel wool” test, such as described in patent application WO 2008/062142. The higher the score obtained (score ranging from 1 to 5), the lower the scratch resistance of the eyeglass.

(23) 4. Results

(24) The tables below collate the optical and mechanical performance of comparative articles or various articles according to the invention and the deposition conditions of the various layers.

(25) TABLE-US-00001 Example 1 Substrate + primer + hard coat ZrO.sub.2 13.5 nm Layer A * 404 nm SiO.sub.2 8 nm ZrO.sub.2 153 nm SiO.sub.2 235 nm ZrO.sub.2 277 nm SiO.sub.2 120 nm Comparative example C1 Substrate + primer + hard coat ZrO.sub.2 13.5 nm SiO.sub.2 412 nm ZrO.sub.2 153 nm SiO.sub.2 235 nm ZrO.sub.2 277 nm SiO.sub.2 120 nm Example 3 Substrate + primer + hard coat ZrO.sub.2 13.5 nm Layer A * 404 nm SiO.sub.2 8 nm ZrO.sub.2 153 nm SiO.sub.2 235 nm ZrO.sub.2 277 nm Layer A * 120 nm Example 2 Substrate + primer + hard coat ZrO.sub.2 13.5 nm SiO.sub.2 412 nm ZrO.sub.2 153 nm SiO.sub.2 235 nm ZrO.sub.2 277 nm Layer A * 120 nm Example 4 Substrate + primer + hard coat ZrO.sub.2 47 SiO.sub.2 50 ZrO.sub.2 54 SiO.sub.2 69 ZrO.sub.2 44 SiO.sub.2 61 ZrO.sub.2 53 Layer A * 132  Comparative example C4 Substrate + primer + hard coat ZrO.sub.2 47 SiO.sub.2 50 ZrO.sub.2 54 SiO.sub.2 69 ZrO.sub.2 44 SiO.sub.2 61 ZrO.sub.2 53 SiO.sub.2 132  Layer A: Decamethyltetrasiloxane. * Deposition under ion assistance.

(26) TABLE-US-00002 Bayer n × 10 Steel Critical T Critical T Resistance to bending, ASTM rubs wool [° C.] [° C.] deformation in mm Example test test test at t + 24 h at t + 1 week before cracking 1 6.8 13 3 60 60 0.66 C1 6.8 13 3 60 50 0.32 2 10.0  13 3 70 70 0.36 3 9.0 13 1-3 70 60 0.63 4 3.2-5.5 13 3 70-80 50-70 0.65 C4 1.6 13 3 70 50 0.44

(27) The articles of examples 1 to 4 exhibit no cracking at the end of their production and performed well in the various durability tests carried out. They have critical temperatures higher by 10 to 20° C. and bending resistances 1.5 to 2 times higher than the articles of the comparative examples the antireflection layers of which contain no organosilicon compound.

(28) The best compromise in the performance level with respect to resistance to bending and abrasion and critical temperature was obtained with example 3.

(29) The resistance to abrasion of the articles of examples 2 and 3 is remarkably high.