Process for obtaining a substrate provided with a coating

Abstract

A process for obtaining a substrate provided with a coating, in which the coating includes a pattern with spatial modulation of at least one property of the coating, includes performing a heat treatment, using a laser radiation, of a continuous coating deposited on the substrate. The heat treatment is such that the substrate is irradiated with the laser radiation focused on the coating in the form of at least one laser line, keeping the coating continuous and without melting of the coating, and a relative displacement of the substrate and of the laser line focused on the coating is imposed in a direction transverse to the longitudinal direction of the laser line, while temporally modulating during this relative displacement the power of the laser line as a function of the speed of relative displacement and of the dimensions of the pattern in the direction of relative displacement.

Claims

1. A process for obtaining a substrate provided, on at least part of at least one of its faces, with a coating comprising a pattern with spatial modulation of at least one property of the coating, the process comprising performing a heat treatment, using a laser radiation, of a continuous coating deposited on the substrate, in which the coating before heat treatment at least partially absorbs the laser radiation, the heat treatment being such that the substrate is irradiated with the laser radiation focused on the coating in the form of at least one laser line, keeping the coating continuous and without melting the coating, and during said heat treatment a relative displacement of the substrate and of the laser line focused on the coating in a direction transverse to a longitudinal direction of the laser line is performed while temporally modulating during the relative displacement a power of the laser line as a function of a speed of the relative displacement and of dimensions of the pattern in the relative displacement direction, wherein the power of the laser line is temporally modulated by temporally modulating an input electrical signal of each laser source forming the laser line, and wherein the laser line is formed using several independent laser sources, the temporal modulation of the input electrical signal being different from one laser source to another forming the laser line during the relative displacement.

2. The process according to claim 1, wherein the coating before heat treatment is monolayer.

3. The process according to claim 1, wherein the coating before heat treatment is a stack of layers, of which at least one layer at least partially absorbs the laser radiation.

4. The process according to claim 1, wherein the coating before heat treatment comprises at least one layer based on at least one metal, metalloid, oxide, nitride, carbide, sulfide, or any mixture thereof.

5. The process according to claim 1, wherein the longitudinal direction of the laser line is substantially perpendicular to the direction of relative displacement.

6. The process according to claim 1, wherein the laser line is fixed and the substrate is moved in translation in a transverse direction relative to the longitudinal direction of the laser line.

7. The process according to claim 1, wherein the pattern has a spatial periodicity and the frequency of temporal modulation of the input electrical signal of the laser source is equal to a ratio of the speed of relative displacement between the substrate and the laser line to the period of the pattern.

8. The process according to claim 1, wherein the temporal modulation of the input electrical signal of the laser source varies during the relative displacement of the substrate and of the laser line.

9. The process according to claim 1, wherein the laser line has a mean width of between 10 m and 1000 m.

10. The process according to claim 9, wherein the mean width is between 30 m and 200 m.

11. The process according to claim 1, wherein the mean power per unit area of the laser line in a focal plane is greater than or equal to 10.sup.3 W/cm.sup.2.

12. The process according to claim 1, wherein each laser source forming the laser line is a continuous or quasi-continuous source.

13. The process according to claim 1, wherein each laser source forming the laser line is a pulsed source and the power of the emitted pulses is temporally modulated.

14. The process according to claim 1, wherein the laser line is fixed and the substrate has at least one first dimension and one second dimension which are mutually transverse, the process comprising at least one first step and one second step such that: in the first step, the substrate is moved in translation parallel to the first dimension and transversely to the longitudinal direction of the laser line, and the power of the laser line is temporally modulated; in the second step, the substrate is moved in translation parallel to the second dimension and transversely to the longitudinal direction of the laser line, and the power of the laser line is temporally modulated.

15. The process according to claim 1, wherein the speed of relative displacement is at least 3 meters per minute.

16. The process according to claim 1, wherein, during the heat treatment, the temperature of the face of the substrate that is opposite from the treated coating is less than or equal to 100 C.

17. The process according to claim 16, wherein, during the heat treatment, the temperature of the face of the substrate that is opposite from the treated coating is less than or equal to 50 C.

18. The process according to claim 17, wherein, during the heat treatment, the temperature of the face of the substrate that is opposite from the treated coating is less than or equal to 30 C.

19. The process according to claim 1, wherein the coating, once treated, comprises a pattern with spatial modulation of at least one property from among electrical conductivity, emissivity, radiation transmission, radiation reflection, radiation absorption, haze, colorimetric coordinates, hydrophilicity, photocatalytic activity of the coating.

20. The process according to claim 1, comprising, prior to performing the heat treatment, a depositing each layer of the coating onto the substrate.

21. A process for obtaining a substrate provided, on at least part of at least one of its faces, with a coating comprising a pattern with spatial modulation of at least one property of the coating, the process comprising performing a heat treatment, using a laser radiation, of a continuous coating deposited on the substrate, in which the coating before heat treatment at least partially absorbs the laser radiation, the heat treatment being such that the substrate is irradiated with the laser radiation focused on the coating in the form of at least one laser line, keeping the coating continuous and without melting the coating, and during said heat treatment a relative displacement of the substrate and of the laser line focused on the coating in a direction transverse to a longitudinal direction of the laser line is performed while temporally modulating during the relative displacement a power of the laser line as a function of a speed of the relative displacement and of dimensions of the pattern in the relative displacement direction, wherein the laser line is formed using several independent laser sources that are controlled during the relative displacement so that the temporal modulation of the power of the laser line varies along the laser line during said displacement, thereby modulating the at least one property of the coating in a longitudinal direction of the laser line.

22. The process according to claim 21, wherein the power of the laser line is temporally modulated by temporally modulating an input electrical signal of each laser source forming the laser line.

Description

(1) The characteristics and advantages of the invention will emerge in the description that follows of several implementation examples of a process and of a substrate according to the invention, which is given solely as an example and with reference to the attached drawings, in which:

(2) FIG. 1 is a top view of a substrate provided on one of its faces with a coating comprising a pattern with spatial modulation of at least one property of the coating, obtained according to the process of the invention, the lower part of FIG. 1 showing the electrical power of square wave type applied as input to the laser sources (Examples 1 and 2);

(3) FIG. 2 is a top view of a substrate provided on one of its faces with a coating comprising a pattern with spatial modulation of at least one property of the coating, obtained according to the process of the invention, the lower part of FIG. 2 showing the electrical power of sinusoidal type applied as input to the laser sources (Example 3);

(4) FIGS. 3 and 4 are top views of a substrate provided on one of its faces with a coating comprising a pattern with spatial modulation of at least one property of the coating, obtained according to the process of the invention comprising two successive heat treatment steps in two mutually perpendicular directions, so as to create a lattice, the lower part of FIGS. 3 and 4 showing the electrical power of square wave type applied as input to the laser sources for each heat treatment step (Examples 4 and 5).

(5) In the examples, the quantities used are the following: the light transmission, in the sense of standard NF EN 410, noted TL and expressed in %, the light reflection, in the sense of standard NF EN 410, noted RL and expressed in %, the square resistance, noted R.sub.c and expressed in ohms, the normal emissivity at a temperature of 283 K, calculated according to standard EN 12898 from a reflection spectrum in the spectral range from 5 to 50 micrometers, noted E.sub.n and expressed in %.

EXAMPLE 1

(6) A layer of titanium metal 6 nm thick is deposited on a main face of a substrate made of silico-sodio-calcic glass, obtained via the float process and then cut into a rectangular shape of length L=6 m and width =3.3 m, via the magnetron process using a titanium target, under an argon plasma.

(7) The substrate thus coated is treated in air using a laser line formed by laser sources of InGaAs laser diode type, which are quasi-continuous sources emitting at a wavelength of between 900 nm and 1000 nm. The laser line has a length of 3.3 m, equal to the width of the substrate, and a mean width of 50 m. The width of the laser line is uniform over the length of the line, such that the difference between the greatest width and the smallest width is 3% of the mean value, i.e. 1.5 m.

(8) The substrate is placed on a roll conveyor so as to travel in a direction X parallel to its length. The laser line is fixed and positioned above the coated face of the substrate with its longitudinal direction Y extending perpendicularly to the direction X of travel of the substrate, i.e. along the width of the substrate, extending over this entire width.

(9) The position of the focal plane of the laser line is adjusted so as to be in the thickness of the titanium layer when the substrate is positioned on the conveyor, the mean power per unit area of the laser line at the focal plane being 10.sup.5 W/cm.sup.2.

(10) The substrate is made to travel under the laser line at a speed of 10 m/min, the speed not varying by more than 1 rel %. During the travel of the substrate under the laser line, a square wave electrical power P.sub.elec is applied as input to the laser diodes, as is seen at the bottom of FIG. 1, which shows the variation of P.sub.elec as a function of the time t. The period of the square wave signal P.sub.elec(t) is 1.2 s and the pulse duration is 300 ms.

(11) As shown in FIG. 1, a substrate is obtained whose coating comprises treated bands of titanium oxide with a width equal to 5 cm parallel to the length of the substrate, resulting from the oxidation of the layer of titanium metal in contact with the air when 100% of the power of the laser line is applied to the layer, which corresponds to the peaks of the square wave signal P.sub.elec(t), these titanium oxide bands being alternated with untreated bands of titanium metal with a width equal to 15 cm parallel to the length of the substrate. The treated bands of titanium oxide have a light transmission TL of 83% and a light reflection RL of 12%, whereas the untreated bands of titanium metal have a light transmission TL of 42% and a light reflection RL of 23%. The coated substrate thus has a striped visual appearance.

EXAMPLE 2

(12) As in Example 1, the heat treatment according to the invention is applied to a substrate made of silico-sodio-calcic glass, obtained via the float process and then cut into a rectangular shape of length L=6 m and width =3.3 m, which was coated on one of its main faces with a layer of titanium metal 6 nm thick, via the magnetron process using a titanium target under an argon plasma.

(13) In Example 2, the laser line used for performing the heat treatment is formed by laser sources of Yb:YAG disc laser type coupled into an optical fiber of 300 m core diameter, emitting at a wavelength of 1030 nm. The laser line has a length of 3.3 m, equal to the width of the substrate, and a mean width of 50 m. The width of the laser line is uniform over the length of the line, such that the difference between the greatest width and the smallest width is 3% of the mean value, i.e. 1.5 m.

(14) As in Example 1, the substrate is placed on a roll conveyor so as to travel in a direction X parallel to its length. The laser line is fixed and positioned above the coated face of the substrate with its longitudinal direction Y extending perpendicularly to the direction X of travel of the substrate, i.e. along the width of the substrate, extending over this entire width.

(15) The position of the focal plane of the laser line is adjusted so as to be in the thickness of the titanium layer when the substrate is positioned on the conveyor, the mean power per unit area of the laser line at the focal plane being 10.sup.5 W/cm.sup.2.

(16) The substrate is made to travel under the laser line at a speed of 10 m/min, the speed not varying by more than 1 rel %. During the travel of the substrate under the laser line, a square wave control voltage of the power P.sub.elec is applied as input to the laser sources, as is seen at the bottom of Figure which shows the variation of P.sub.elec as a function of the time t. The period of the square wave signal P.sub.elec(t) is 1.2 s and the pulse duration is 300 ms.

(17) A substrate as shown in FIG. 1 is thus obtained, whose coating comprises treated bands of titanium oxide with a width equal to 5 cm parallel to the length of the substrate, resulting from the oxidation of the layer of titanium metal in contact with the air when 100% of the power of the laser line is applied to the layer, which corresponds to the peaks of the square wave signal P.sub.elec(t), these titanium oxide bands being alternated with untreated bands of titanium metal with a width equal to 15 cm parallel to the length of the substrate. The treated bands of titanium oxide have a light transmission TL of 83% and a light reflection RL of 12%, whereas the untreated bands of titanium metal have a light transmission TL of 42% and a light reflection RL of 23%.

EXAMPLE 3

(18) As in Examples 1 and 2, the heat treatment according to the invention is applied to a substrate made of silico-sodio-calcic glass, obtained via the float process and cut into a rectangular shape of length L=6 m and width =3.3 m, which was coated on one of its main faces with a layer of titanium metal 6 nm thick, via the magnetron process using a titanium target under an argon plasma.

(19) In Example 3, the laser line used for performing the heat treatment is formed by pulsed laser sources, with a pulse duration of 400 fs and a repeat rate of 500 kHz, emitting at a wavelength of 1040 nm. The laser line has a length of 3.3 m, equal to the width of the substrate, and a mean width of 50 m. The width of the laser line is uniform over the length of the line, such that the difference between the largest width and the smallest width is 3% of the mean value, i.e. 1.5 m.

(20) The substrate is placed on a roll conveyor so as to travel in a direction X parallel to its length. The laser line is fixed and positioned above the coated face of the substrate with its longitudinal direction Y extending perpendicular to the direction X of travel of the substrate, i.e. along the width of the substrate, extending throughout this width.

(21) The position of the focal plane of the laser line is adjusted so as to be in the thickness of the titanium layer when the substrate is positioned on the conveyor, the mean power per unit area of the laser line at the focal plane being 10.sup.3 W/cm.sup.2.

(22) The substrate is made to travel under the laser line at a speed of 10 m/min, the speed not varying by more than 1 rel %. During the travel of the substrate under the laser line, an electrical power P.sub.elec of sinusoidal type is applied as input to the laser sources, as is seen at the bottom of FIG. 2, which shows the variation of P.sub.elec as a function of the time t. The period of the sinusoidal signal P.sub.elec(t) is 1.2 s, which makes it possible to temporally modulate the power of the pulses of the laser sources as shown schematically in FIG. 2 in which only a few pulses have been represented in the sinusoidal signal envelope.

(23) As shown in FIG. 2, a substrate is obtained whose coating comprises a pattern with modulation of its light transmission TL and of its light reflection RL having a spatial periodicity of 15 cm, with a gradient of TL and RL alternately increasing and decreasing in the length direction of the substrate. The zones of highest TL, which have a TL equal to 83% and an RL equal to 12%, are titanium oxide bands resulting from the oxidation of the layer of titanium metal in contact with the air when 100% of the power of the laser line is applied to the layer, which corresponds to the peaks of the sinusoidal signal P.sub.elec(t). The zones of lowest TL, which have a TL equal to 42% and an RL equal to 23%, are untreated bands of titanium metal, which corresponds to the troughs of the sinusoidal signal P.sub.elec(t).

EXAMPLE 4

(24) A stack of thin layers comprising a silver layer, the said silver layer giving the glass low-emissivity properties, is deposited in a known manner via the magnetron process onto a main face of a substrate made of silico-sodio-calcic glass, obtained via the float process and then cut into a square shape with a side length of 3.3 m.

(25) This stack comprises in order (from the substrate to the outer surface) the following layers of oxides, metals or nitrides, the geometrical thicknesses being indicated in parentheses:
Glass/SnO.sub.2 (20 nm)/ZnO (15 nm)/Ag (8.5 nm)/NiCr/ZnO (15 nm)/Si.sub.3N.sub.4 (25 nm).

(26) In Example 4, the process comprises two successive heat treatment steps, the first step being identical to the treatment applied to the coated substrate in Example 1, with the substrate which travels parallel to one of its sides C1, and the second step also being identical to the treatment applied to the coated substrate in Example 1, but the substrate travelling this time parallel to another of its sides C2 perpendicular to the side C1. This second step is illustrated in FIG. 3.

(27) As shown in FIG. 3, a substrate is obtained whose coating comprises a pattern with modulation of its properties in the form of a lattice, the strands of the lattice being treated strips with a width equal to 5 cm, which delimit between them untreated zones having a square shape with a side length of 15 cm. The treated strips have a square resistance R.sub.c of 4.5 and a normal emissivity .sub.n of 5.0%, whereas the untreated zones have a square resistance R.sub.c of 5.5 and a normal emissivity .sub.n of 6.0%. The glazing obtained thus has an openwork pattern of reflection of infrared radiation making it possible to control the gain in solar heat.

EXAMPLE 5

(28) A layer of titanium metal 6 nm thick is deposited in a known manner via the magnetron process using a titanium target, under an argon plasma, onto a main face of a substrate made of silico-sodio-calcic glass, obtained via the float process and then cut into a square shape with a side length of 3.3 m.

(29) As in Example 4, the process comprises two successive heat treatment steps. The first step is substantially identical to the treatment applied to the coated substrate in Example 1, with the substrate which travels parallel to one of its sides C1, except that the square wave electrical power P.sub.elec(t) which is applied as input to the laser diodes is the one visible at the bottom of FIG. 4, in which the period of the signal is 3 ms and the pulse duration is 300 s. The second step is identical to the first step, but with the substrate which travels this time parallel to one of its other sides C2 perpendicular to the side C1. This second step is illustrated in FIG. 4.

(30) As shown in FIG. 4, a substrate is obtained whose coating comprises a pattern with modulation of its electrical conductivity in the form of a lattice, the strands of the lattice being untreated strips with a width equal to 50 m, which delimit between them treated zones having a square shape with a side length of 500 m. The treated zones have a square resistance R.sub.c of 2000, whereas the untreated strips have a square resistance R.sub.c of 400 . The glazing obtained thus has a conductive grid on its surface.