Production Method for Sheets of Glass with a Diffuse Finish, and Resulting Sheet of Glass

Abstract

The present invention relates to a process for manufacturing glass sheets with diffuse finish and the resulting glass sheet by this process. The glass sheet is subjected to a series of alternate immersions in acidic solutions and alkaline solutions to remove impurities and waste and to generate a diffuse finish on both sides of the glass sheet. The process generates in the glass sheet in at least one side, a diffuse surface with a peak to valley roughness (Rt) of between 5.8343 ?m and 9.3790 ?m; an average roughness (Ra) value between 0.8020 ?m and 0.9538 ?m; an RMS roughness between 0.9653 ?m and 1.1917 ?m; a solar transmission between 84.8% and 46.50%; a solar reflection between 7.4 and 4.4%; a light transmission between 88.5% and 67.70%; a reflection of light between 6.50% and 5.20%; and UV transmission between 35.60% and 70.20%.

Claims

1. A process for manufacturing glass sheets with diffuse finish comprising the steps of: a) Providing at least one sheet of glass; b) Providing a first immersion of at least one glass sheet in a first acidic solution for a predetermined time, to remove the impurities from the glass; c) Rinsing or washing the glass sheets once they have been immersed in the first acidic solution to remove the remaining acidic solution and avoid the formation of undesirable lines and marks in the glass; d) Providing a second immersion step to said glass sheet in a second acidic solution for a second predetermined time to generate a diffuse finish on both sides of the glass; e) Providing a third step of immersing the glass sheet from step d) in an alkaline solution in a third predetermined period. f) Rinsing or washing the glass sheets to remove any residual alkaline solution from the glass sheet; g) Providing a fourth immersion step to said glass sheet in a third acidic solution for a third predetermined period; h) Providing a fifth step of immersing the glass sheet from step g) in the alkaline solution of step e) to stop the reaction of the third alkaline solution in said glass sheet; and, i) Rinsing the glass sheet to remove residues of the alkaline solution.

2. The manufacturing process of glass sheets with diffuse finish in accordance with claim 1, wherein after step i) it comprises the step of: drying the glass sheet for storage.

3. The manufacturing process of glass sheets with diffuse finish in accordance with claim 1, wherein the first acidic solution is a hydrochloric acid solution.

4. The manufacturing process of glass sheets with diffuse finish in accordance with claim 3, wherein the hydrochloric acid solution is a solution of 32.5% hydrochloric acid.

5. The manufacturing process of glass sheets with diffuse finish in accordance with claim 1, wherein the time of immersion of the first glass sheet in step b) is from 20 to 60 seconds.

6. The manufacturing process of glass sheets with diffuse finish in accordance with claim 1, wherein the second acidic solution is a solution selected of ammonium difluoride, hydrochloric acid or a mixture thereof.

7. The manufacturing process of glass sheets with diffuse finish in accordance with claim 6, wherein the second acidic solution is a mixture of 70% Ammonium Difluoride and 30% of 32.5% hydrochloric acid.

8. The manufacturing process of glass sheets with diffuse finish in accordance with claim 1, wherein the second immersion time of the glass sheet in step d) is from 30 to 300 seconds.

9. The manufacturing process of glass sheets with diffuse finish in accordance with claim 1, wherein the third acidic solution is a hydrofluoric acid solution.

10. The manufacturing process of glass sheets with diffuse finish in accordance with claim 9, wherein the third acidic solution is a 35% hydrofluoric acid solution.

11. The manufacturing process of glass sheets with diffuse finish in accordance with claim 1, wherein the time of immersion of the first glass sheet in step g) is from 30 to 600 seconds.

12. The manufacturing process of glass sheets with diffuse finish in accordance with claim 1, wherein the alkaline solution is a caustic soda solution.

13. The manufacturing process of glass sheets with diffuse finish in accordance with claim 12, wherein the caustic solution has a concentration of 2%.

14. The manufacturing process of glass sheets with diffuse finish in accordance with claim 1, wherein the immersion time in the alkaline solution of step e) is between 2 and 5 minutes.

15. The manufacturing process of glass sheets with diffuse finish in accordance with claim 1, wherein the immersion time in the alkaline solution of step h) is between 20 and 60 seconds.

16. The manufacturing process of glass sheets with diffuse finish in accordance with claim 1 wherein the glass sheet is supplied with a thickness between 2 and 19 mm.

17. A glass sheet with diffuse finish produced according to the process claimed in claim 1 wherein the process generates in the glass sheet, on at least one side, a diffuse surface with a peak-valley roughness (Rt) from 5.8343 ?m to 9.3790 ?m; an average roughness (Ra) between 0.8020 ?m and 0.9538 ?m; RMS roughness between 0.9653 ?m and 1.19167 ?m; a solar transmission between 84.8% and 46.50%; a solar reflection between 7.4 and 4.4%; a light transmission between 88.5% and 67.70%; a reflection of light between 6.50% and 5.20%; and UV transmission between 35.60% and 70.20%.

18. A glass sheet with diffuse finish produced according to the process claimed in claim 1 wherein the process generates in the glass sheet, in at least one side, a diffuse surface comprising: a peak-valley roughness (Rt) of about 5.9244 ?m; an Ra roughness of about 0.7081 ?m; an RMS roughness of about 0.8764 ?m; a solar transmission of at least 84%; a solar reflectance of about 7.3%; a light transmission of about 88.5%; and UV transmission of about 64.2%.

19. A glass sheet with diffuse finish produced per the process claimed in claim 1 wherein the process includes in the glass sheet, in at least one side, a diffuse surface without attack, comprising: one peak-valley roughness (Rt) of about 0.0641 ?m; an Ra roughness of about 0.0091 ?m; and an RMS roughness of about 0.0111 ?m.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG. 1 a shows an image of roughness for ATR glass, 3-dimensional, side one.

[0022] FIG. 2 shows a plot of roughness, in one dimension, for ATR glass, side one.

[0023] FIG. 3 shows an image of roughness for ATR glass, 3-dimensional, side two.

[0024] FIG. 4 shows a plot of roughness, in one dimension, for ATR glass, side two.

[0025] FIG. 5 shows an image of roughness for PAVIA glass, 3-dimensional, side one.

[0026] FIG. 6 shows a plot of roughness, in one dimension, for PAVIA glass, side one.

[0027] FIG. 7 shows an image of roughness for PAVIA glass, 3-dimensional, side two.

[0028] FIG. 8 shows a plot of roughness, in one dimension, for PAVIA glass, side two.

DETAILED DESCRIPTION OF THE INVENTION

[0029] Referring to the manufacturing process of glass sheets comprising the following steps:

[0030] a) Providing Flat Glass Plates

[0031] For the start of the manufacturing process, packages of flat glass are supplied, to be processed in groups, which are received in storage racks specially designed so that the glass does not suffer any damage either by scratches or breaks.

[0032] b) Immersion of Glass Plates in an Acid Solution

[0033] The next step is to introduce at least one glass sheet in a first acidic solution. Such a solution may be a solution of 32.5% hydrochloric acid for a time from 20 to 60 seconds, to remove all impurities that may be present in the sheets of flat glass such as any remains of separator dust, fingerprint marks, glove stains, etc. This process is carried out in a container that can process from 1 to 7 sheets of minimum size 1200 cm by 1800 cm and maximum dimensions of 1800 cm by 2600 cm with thicknesses ranging from 2.0 mm to 19 mm which is equivalent to processing from 75.6 kg to 1556.1 kg of glass.

[0034] c) Rinsing Glass Sheets.

[0035] Once the glass sheet has been subjected to the acidic solution, the sheets are subjected to a washing or rinsing process to remove the remaining acid solution and avoid the formation of lines and undesirable marks in the flat glass.

[0036] d) Immersion of Glass Sheets in a Second Acidic Solution

[0037] Once the remains of the first acidic solution (hydrochloric acid) are removed, the sheet or sheets of glass are subjected to a second immersion in a second acidic solution composed of a mixture of 70% ammonium difluoride and 30% hydrochloric acid 32.5% for a period of between 30 seconds and 300 seconds. Immersing the glass sheets in this mixture produces a finish on both sides of the glass sheets but also leaves a crust on them, which must be removed.

[0038] e) Immersion of Glass Sheet in an Alkaline Solution.

[0039] To achieve crust removal, it is necessary to introduce again the glass sheet or sheets in an alkaline solution, such as a 2% solution of caustic soda. To facilitate removal of the crust, the caustic solution is subjected to a stirring by bubbling process, for a time from 2 minutes to 5 minutes depending on the degree of crust removal.

[0040] f) Flushing Glass Plates

[0041] After removing the crust the glass sheet is carried to a second rinse step and the residual caustic soda solution present in the sheets and container is removed.

[0042] g) Immersion of Glass Sheets in an Acidic Solution

[0043] The next step is to introduce again one or more sheets of glass in an acidic solution. Said acidic solution may be a solution of 32.5% hydrofluoric acid. The immersion time will be from 30 to 600 seconds. With this immersion, the opacity generated in the previous step can be eliminated, keeping the roughness originated on the surface of the glass, making the glass resume its transparency but with a low level of light reflection.

[0044] h) Immersion of Glass Sheets in an Alkaline Solution.

[0045] Once completed the attack time with the 35% hydrofluoric acid solution, the glass sheet or sheets are introduced again in a tank containing a solution of 2% caustic soda. This stage aims to stop the reaction of hydrofluoric acid with glass. Such glass sheets are kept within the tank from 20 seconds to 60 seconds as required.

[0046] i) Rinsing and Drying the Glass Sheets

[0047] Once the glass sheet was treated with caustic soda, a second step of rinsing and drying takes place, to remove the residual solution of caustic soda present in the sheets and the tank.

[0048] Finally, once the product meets the required specifications and quality, it is taken to storage.

[0049] Per the above-described process, roughness measurements were made by profilometry for glass types ATR (anti reflection) and PAVIA? (Trademark of company Vitro Vidrio y Cristal), on both faces.

[0050] All measurements were made under the following conditions:

[0051] Swept area: 1.2?1.2 cm with sweeping steps every 1 ?m.

[0052] Force applied to the sample: 10 mg.

[0053] Sweeping speed: 200 ?m.Math.s.sup.?1

[0054] At atmospheric pressure and room temperature.

[0055] The results obtained are summarized in Tables 1, 2 and 3. FIGS. 1 to 8 show for each measurement, an image of 3D roughness and a graph of the roughness in one dimension.

TABLE-US-00001 TABLE 1 Parameters obtained from measurements ATR PAVIA Side 1 side 2 Side 1 side 2 PARAMETER (attack) (attack) (attack) (No attack) Roughness peak - 5.8343 ?m 5.9244 ?m 9.3790 ?m 0.0641 ?m valley (Rt) Roughness average 0.8020 ?m 0.7081 ?m 0.9538 ?m 0.0091 ?m (Ra) Roughness RMS 0.9653 ?m 0.8764 ?m 1.1917 ?m 0.0111 ?m

TABLE-US-00002 TABLE 2 Optical Properties of Anti-Glare Glass (ATR) Sample R Solar R Solar R light R Light (thickness) T Solar (Front) (Back) T light (Front) (Back) T UV 2.0 ATR 84.8% 7.4% 7.3% 88.5% 7.8% 7.7% 64.2% Color T Color RDP Color RDV Sample L* a* b* L* a* b* L* a* b* 2.0 ATR 95.353 ?0.698 0.256 33.515 ?0.585 ?0.347 33.345 ?0.582 ?0.231 T Solar: Solar transmission; R Solar: Solar reflection; T light: Light Transmission; R Light: Light reflection

TABLE-US-00003 TABLE 3 Optical Properties of PAVIA Anti-Glare Glass Sample R Solar R Solar R light (thickness) T Solar (Front) (Back) T light (Front) R Light (Back) T UV 3.0 PAVIA 82.60% 6.00% 6.00% 88.60% 6.50% 6.50% 70.20% Color T Color RDP Color RDV (Color to (Color to reflection (Color to reflection Transmission) film side) glass side) Sample L* a* b* L* a* b* L* a* b* 3.0 PAVIA 95.43 0.119 0.298 30.58 4.25 10.18 30.58 4.25 10.18 Sample R Solar R Solar R light (thickness) T Solar (Front) (Back) T light (Front) R Light (Back) T UV 6.0 PAVIA 74.10% 5.50% 5.50% 84.50% 6.20% 6.20% 59.60% Color T Color RDP Color RDV Sample L* a* b* L* a* b* L* a* b* 6.0 PAVIA 93.67 0.16 0.412 29.93 4.32 10.41 29.93 4.32 10.41 Sample R Solar R Solar R light (thickness) T Solar (Front) (Back) T light (Front) R Light (Back) T UV 12.0 PAVIA 59.10% 4.80% 4.80% 76.10% 5.70% 5.70% 45.70% Color T Color RDP Color RDV Sample L* a* b* L* a* b* L* a* b* 12.0 PAVIA 89.98 0.249 0.662 28.66 4.47 10.86 28.66 4.47 10.86 Sample R Solar R Solar R light (thickness) T Solar (Front) (Back) T light (Front) R Light (Back) T UV 19.0 PAVIA 46.50% 4.40% 4.40% 67.70% 5.20% 5.20% 35.60% Color T Color RDP Color RDV Sample L* a* b* L* a* b* L* a* b* 19.0 PAVIA 85.94 0.351 0.953 27.64 4.64 11.33 27.46 4.64 11.33

[0056] From the above, a manufacturing process has been described to manufacture a diffuse glass and a resulting glass and it will be apparent to those skilled in the art that other possible advances or improvements can be performed, which may be considered within the field determined by the following claims.