Item coated with a silicon/organic layer improving the performances of an outer coating

Abstract

The invention concerns an item comprising a substrate having at least one main surface coated with a layer A in direct contact with a hydrophobic outer layer B, characterized in that said layer A has been obtained by depositing, under ion beam, activated species from at least one compound C, in gas form, containing, in the structure of same: at least one carbon atom, at least one hydrogen atom, at least one SiX group, in which X is a hydroxy group or a hydrolysable group chosen from the H, halogen, alkoxy, aryloxy and acyloxy groups, NR.sup.1R.sup.2 in which R.sup.1 and R.sup.2 separately designate a hydrogen atom, an alkyl group or an aryl group, and N(R.sup.3)Si in which R.sup.3 designates an alkyl group or an aryl group, said compound C being neither tetramethyldisiloxane nor tetraethoxysilane, nor vinylmethyldiethoxysilane, nor hexamethylcyclotrisilazane, said layer A not being formed from inorganic precursor compounds.

Claims

1. An article comprising a substrate having at least one main surface coated with a layer A making direct contact with a hydrophobic external coating B, wherein the atomic percentage of carbon atoms in layer A ranges from 8 to 25%, and layer A is obtained by depositing, under an ion beam, activated species originating from at least one compound C, in gaseous form, comprising in its structure: at least one carbon atom; at least one hydrogen atom; and at least one SiX group, where X is a hydroxy group or a hydrolyzable group chosen from the groups H, halogen, alkoxy, aryloxy, acyloxy, NR.sup.1R.sup.2 where R.sup.1 and R.sup.2 designate independently a hydrogen atom, an alkyl group or an aryl group, and N(R.sup.3)Si where R.sup.3 designates an alkyl group or an aryl group; said compound C being neither tetramethyldisiloxane, nor tetraethoxysilane, nor vinylmethyldiethoxysilane, nor hexamethylcyclotrisilazane and said layer A not being formed from inorganic precursor compounds, wherein the article is further defined as an ophthalmic lens.

2. The article as claimed in claim 1, wherein the ion beam is emitted by an ion gun.

3. The article as claimed in claim 1, wherein the compound C contains at least one SiC bond.

4. The article as claimed in claim 1, wherein the silicon atom of the group SiX is directly bonded to at least one carbon atom.

5. The article as claimed in claim 1, wherein the compound C contains at least one group of formula: ##STR00004## where R.sup.1 to R.sup.4 independently designate alkyl, vinyl or aryl groups or a group X, one at least of R.sup.1 to R.sup.4 designating a group X, X being such as defined in claim 1.

6. The article as claimed in claim 1, wherein the compound C is a compound of formula: ##STR00005## where X is such as defined in claim 1, n designates an integer ranging from 2 to 20 and R.sup.1a and R.sup.2a represent independently an alkyl, vinyl or aryl group or a hydrolyzable group.

7. The article as claimed in claim 1, wherein the layer A has a thickness ranging from 20 to 150 nm.

8. The article as claimed in claim 1, wherein the group SiX is an SiH group.

9. The article as claimed in claim 1, wherein the layer A has a refractive index lower than or equal to 1.55.

10. The article as claimed in claim 9, wherein the layer A is the external layer of a multilayer interference coating.

11. The article as claimed in claim 10, wherein the interference coating is an antireflection coating.

12. The article as claimed in claim 10, wherein the interference coating contains low refractive index layers having a refractive index lower than or equal to 1.55 and in that all these low refractive index layers are inorganic in nature except for the layer A.

13. The article as claimed in claim 10, wherein all the layers of the interference coating are inorganic in nature, except for the layer A.

14. The article as claimed in claim 1, wherein the silicon atom of the group SiX is not bonded to more than two non-hydrolyzable groups.

15. The article as claimed in claim 4, wherein the silicon atom of the group SiX is directly bonded to at least one alkyl group.

16. A process for manufacturing the article of claim 1, comprising at least the following steps: providing an article comprising a substrate having at least one main surface; depositing on said main surface of the substrate a layer A, wherein the atomic percentage of carbon atoms in layer A ranges from 8 to 25%; depositing directly on said layer A a hydrophobic external coating B; obtaining an article comprising a substrate having a main surface coated with said layer A making direct contact with the hydrophobic external coating B, said layer A having been obtained by depositing, under an ion beam, activated species originating from at least one compound C, in gaseous form, comprising in its structure: at least one carbon atom; at least one hydrogen atom; and at least one SiX group, where X is a hydroxy group or a hydrolyzable group chosen from the groups H, halogen, alkoxy, aryloxy, acyloxy, NR.sup.1R.sup.2 where R.sup.1 and R.sup.2 designate independently a hydrogen atom, an alkyl group or an aryl group, and N(R.sup.3)Si where R.sup.3 designates an alkyl group or an aryl group; said compound C being neither tetramethyldisiloxane, nor tetraethoxysilane, nor vinylmethyldiethoxysilane, nor hexamethylcyclotrisilazane and said layer A not being formed from inorganic precursor compounds, wherein the article is further defined as an ophthalmic lens.

17. The article as claimed in claim 1, wherein layer A is deposited without plasma assistance at the substrate level.

18. The process as claimed in claim 16, wherein layer A is deposited without plasma assistance at the substrate level.

19. The article as claimed in claim 1, wherein the atomic percentage of oxygen atoms in layer A ranges from 20 to 60%.

20. The article as claimed in claim 1, wherein the atomic percentage of oxygen atoms in layer A ranges from 35 to 45%.

21. The article as claimed in claim 1, wherein compound C further comprises at least one nitrogen atom and/or at least one oxygen atom.

22. The process as claimed in claim 16, wherein compound C further comprises at least one nitrogen atom and/or at least one oxygen atom.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1. Depiction of deformation D that the eyeglass can experience before cracks appear.

(2) The invention is illustrated in a nonlimiting way by the following examples. Unless otherwise indicated, refractive indices are given for a wavelength of 630 nm and T=20-25? C.

EXAMPLES

1. General Procedures

(3) The articles employed in the examples comprised a 65 mm-diameter ORMA? ESSILOR lens substrate with a power of ?2.00 diopters and a thickness of 1.2 mm (except for the tests for evaluating the possible presence of cosmetic defects, which were carried out on MR8 thiourethane substrates from Mitsui Toatsu Chemicals Inc., of refractive index of 1.59, all else moreover being equal), coated on its concave face with the anti-shock primer coating and the anti-scratch and anti-abrasion coating (hard coat) disclosed in the experimental section of the patent application WO 2010/109154, with an antireflection coating and with the anti-smudge coating disclosed in the experimental section of patent application WO 2010/109154.

(4) The layers of the antireflection coating were deposited, without heating the substrates, by vacuum evaporation optionally, when specified, assisted during the deposition by a beam of oxygen and possibly argon ions (evaporation source: electron gun).

(5) The vacuum deposition reactor was a Leybold LAB 1100+ machine 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 use in the preliminary phase of (IPC) preparation of the surface of the substrate by argon ion bombardment and in the ion-assisted deposition (IAD) of the layer A or of other layers, and with a system for introducing liquid, which system was used when the precursor compound of the layer A was a liquid under standard temperature and pressure conditions (the case of TMCTS). This system comprises a reservoir containing the liquid precursor compound of the layer A, resistive heaters for heating the reservoir, tubes connecting the reservoir of liquid precursor to the vacuum deposition machine, and a vapor flowmeter from MKS (MKS1150C), raised to a temperature of 30-150? C. during its use, depending on the flow rate of the vaporized precursor, which preferably varied from 10 to 50 sccm. The precursor vapor exited from a tube inside the machine, at a distance of about 30 cm from the ion gun. Flows of oxygen and optionally of argon were introduced into the ion gun. Preferably, neither argon or any other noble gas is introduced into the ion gun.

(6) The layers A according to the invention were formed by evaporation under ion bombardment of TMCTS compound.

(7) The thickness of the deposited layers was controlled in real time by means of a quartz microbalance. Unless otherwise indicated, the thicknesses mentioned are physical thicknesses. A number of samples of each eyeglass were prepared.

2. Operating Modes

(8) The method used to produce optical articles according to the invention comprised introducing the substrate coated with the primer coating and the anti-abrasion coating defined above into the vacuum deposition chamber; a step of preheating the vaporizer, tubes and the vapor flowmeter to the chosen temperature (?20 min); a primary pumping step; then a secondary pumping step lasting 400 seconds and allowing a secondary vacuum to be obtained (?2?10.sup.?5 mbar, pressure read from a Bayard-Alpert gauge); a step of activating the surface of the substrate with a beam of argon ions (IPC: 1 minute, 100 V, 1 A, the ion gun being stopped at the end of this step); then deposition by evaporation of the following inorganic layers using the electron gun until the desired thickness was obtained for each layer: a 20 nm-thick ZrO.sub.2 layer, a 25 nm-thick SiO.sub.2 layer, a 80 nm-thick ZrO.sub.2 layer, and a 6 nm-thick electrically conductive ITO layer deposited with oxygen-ion assistance.

(9) The layer A was then deposited on the ITO layer in the following way.

(10) The ion gun was then started with argon, oxygen was added in the ion gun with a set flow rate (20 sccm), the flow of argon was cut, the desired anode current (3 A) was input and the TMCTS compound was introduced into the chamber (flow rate set to 20 sccm). (Summary of the deposition conditions (flow rates): TMCTS: 20 sccm; Ar: 0 sccm; and O.sub.2: 20 sccm; current 3 A).

(11) Generally, the process according to the invention is carried out with oxygen (O.sub.2) in the ion gun, in the absence of noble gas introduced into the ion gun.

(12) The TMCTS compound supply was stopped once the desired thickness had been obtained, then the ion gun was turned off.

(13) In example 1, an anti-smudge coating layer (top coat) based on Optool DSX? from Daikin and of about 5 nm was deposited directly on an 85 nm-thick layer A that formed the external layer of the antireflection coating.

(14) Lastly, a venting step was carried out.

(15) Comparative example 1 differs from the stack according to the invention in that the layer A is replaced with a silica layer of the same thickness (85 nm).

(16) Comparative example 2 differs from the stack according to the invention in that the layer A is replaced by a layer of the same thickness (85 nm) obtained under the same conditions by evaporating, under ion bombardment, the compound OMCTS (octamethylcyclotetrasiloxane, which possesses no Si-hydrolyzable group bond) provided by the company ABCR, in place of the compound TMCTS. The article of comparative example 2 is in accordance with those forming the subject matter of patent application PCT/FR 12053092.

3. Characterizations

(17) Abrasion resistance was evaluated by determining Bayer ASTM (Bayer sand) values for substrates coated with the antireflection coating and anti-smudge 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.

(18) The critical temperature of the article was measured in the way indicated in patent application WO 2008/001011, 24 hours after the preparation of this article.

(19) The bending resistance test allowed the capacity of an article having a curvature to undergo a mechanical deformation to be evaluated. This test was carried out on an initially spherical lens that was trimmed to the shape of a rectangle of 50?25 mm size. The forces applied in this test were representative of the forces applied at an optician's when fitting the glass, i.e. when the glass is compressed in order to be inserted into a metal frame. This test used an Instron machine to controllably deform the eyeglass, light-emitting diodes (LEDs) to illuminate the eyeglass, a video camera and an image-analyzing software package. The coated eyeglass was compressed by the Instron machine, by applying forces exerted along the axis of the main length of the trimmed eyeglass until cracks appeared, perpendicular to the movement direction, in the antireflection coating, which cracks were detected by image analysis in transmission. The result of the test was the critical deformation D in mm that the eyeglass can experience before cracks appear, see FIG. 1. This test was carried out one month after the eyeglasses had been produced. The higher the value of the deformation, the better the resistance to the applied mechanical deformation.

(20) Generally, interference coatings according to the invention have critical deformation values ranging from 0.7 to 1.2 mm, preferably from 0.8 to 1.2 mm and more preferably from 0.9 to 1.2 mm.

(21) The possible presence of cosmetic defects in the optical articles (articles according to the invention or comparative articles) was evaluated visually under an arc lamp (high-intensity lamp), after storage of the articles under tropical conditions in an environmental chamber regulated to 40? C. with 80% relative humidity at atmospheric pressure, and for a set length of time (t0+1 week or t0+1 month, the reference time t0 corresponding to 1 day after preparation of the articles). The expression atmospheric pressure is understood to mean a pressure of 1.01325 bar. These storage conditions allowed the optical articles to be prematurely aged and the possible appearance of cosmetic defects to be accelerated. The defects visible under the arc lamp took the form of spots or small filaments. These were localized optical defects. Although the most pronounced were visible to the naked eye in reflection at a grazing angle, observation thereof was facilitated by use of an arc lamp.

(22) The adhesion test allowed the adhesive properties of the coating to be evaluated; it consisted in dipping the article into warm water and then stressing its surface mechanically. The higher the result obtained the better the adhesion.

(23) The ink test allowed the performance of the anti-smudge coating to be evaluated. This test consisted in drawing a line with a No. 500 magic ink felt tip from Teranishi Chemical Industries Ltd, and in then evaluating the trace left on the eyeglass. If the ink rapidly retracted (<3 s) into small droplets, the result was considered to be a pass. If the trace was continuous or contained continuous intervals, the result was considered to be a fail.

4. Results

(24) The tables below indicate for each of the examples and comparative examples the results of the tests to which the prepared articles were subjected.

(25) TABLE-US-00001 Bending resistance test, Critical deformation Bayer temperature Adhesion in mm before Ink Example sand (? C.) test cracking test 1 6 110 4.9 0.9 pass Comparative 1 4.5 70 5 0.6 pass Comparative 2 7.5 100 4.3 0.9 fail
Possible Presence of Cosmetic Defects

(26) TABLE-US-00002 t0 (ambient t0 + 1 week temperature of tropical t0 + 1 month of tropical Example and humidity) storage storage 1 no no yes for 1 eyeglass in 2 Comparative 1 no no no Comparative 2 slight yes yes

(27) The article according to the invention has a better critical temperature and exhibits a significant improvement in how far it can be bent before cracks appear, relative to comparative example 1. These improvements are directly attributable to the presence of a layer A in the antireflection stack. It will be noted that it is not necessary for all the layers of the antireflection coating to be layers of organic nature, like the layer A, to obtain an improvement in the behavior of the product with respect to thermomechanical stresses.

(28) The article according to the invention possesses an anti-smudge coating that has a higher performance than that of comparative example 2 and a performance equal to the anti-smudge coating deposited on a silica layer (comparative example 1), as revealed by the ink test, while preserving good mechanical properties. It will be noted that the use of other precursors such as hexamethyldisiloxane, decamethyltetrasiloxane or decamethylcyclopentasiloxane, which like OMCTS do not possess Si-hydrolyzable group bonds, lead to anti-smudge coating performances poorer than those obtained using a layer A according to the invention. Furthermore, the article according to the invention has a limited tendency to develop cosmetic defects over time, whereas that of comparative example 2 exhibits such defects a relatively short time after its preparation.