STRUCTURED ZIRCONIUM SOLUTIONS

Abstract

This invention relates to azirconium solution or sol comprising: (a) zirconium, (b) nitrate, acetate and/or chloride ions, and (c) one or more complexing agents being an organic compound comprising at least one of the following functional groups: an amine, an organosulphate, a sulphonate, a hydroxyl, an ether or a carboxylic acid group, wherein the molar ratio of components (a):(b) is 1:0.7 to 1:4.0, the molar ratio of components (a):(c) is 1:0.0005 to 1:0.1, and the pH of the zirconium solution or sol is less than 5. The invention also relates to a process for preparing a zirconium solution or sol, the process comprising the steps of: (a) dissolving a zirconium salt in nitric, acetic and/or hydrochloric acid, and (b) adding one or more complexing agents to the resulting solution, the one or more complexing agents being an organic compound comprising at least one of the following functional groups: an amine, an organosulphate, a sulphonate, a hydroxyl, an ether or a carboxylic acid group, and (c) heating the solution or sol to a temperature of at least 75? C. In addition, the invention relates to products formed from the zirconium solution or sol or obtainable by the process.

Claims

1. A zirconium solution or sol comprising: (a) zirconium, (b) nitrate, acetate and/or chloride ions, and (c) one or more complexing agents being an organic compound comprising at least one of the following functional groups: an amine, an organosulphate, a sulphonate, a hydroxyl, an ether or a carboxylic acid group, wherein the molar ratio of components (a):(b) is 1:0.7 to 1:4.0, the molar ratio of components (a):(c) is 1:0.0005 to 1:0.1, and the pH of the zirconium solution or sol is less than 5.

2. A zirconium solution or sol as claimed in claim 1 wherein when the solution or sol comprises nitrate ions as component (b), the molar ratio of components (a):(b) is 1:0.8 to 1:2.0; when the solution or sol comprises acetate ions as component (b), the molar ratio of components (a):(b) is 1:1.5 to 1:4.0; and when the solution or sol comprises chloride ions as component (b), the molar ratio of components (a):(b) is 1:0.7 to 1:2.2.

3. A zirconium solution or sol as claimed in claim 1, comprising nitrate ions as component (b).

4. A zirconium solution or sol as claimed in claim 1 having a refractive index of at least 1.34.

5. A zirconium solution or sol as claimed in claim 1, wherein the conductivity in mS/cm is at least 10% higher after being heated to a temperature of 94? C. at a heating rate of 1? C./min, with a dwell time of 2 hours.

6. A zirconium solution or sol as claimed in claim 3, wherein there is an increase in size of the absorbance peak at 361 nm as measured by UV-Vis spectroscopy by a factor of 2.7 after the solution is heated to a temperature of 94? C. at a heating rate of 1? C./min, with a dwell time of 2 hours.

7. A zirconium solution or sol as claimed in claim 1, wherein component (a) is zirconium basic sulphate.

8. A process for preparing a zirconium solution or sol, the process comprising the steps of: (a) dissolving a zirconium salt in nitric, acetic and/or hydrochloric acid, and (b) adding one or more complexing agents to the resulting solution, the one or more complexing agents being an organic compound comprising at least one of the following functional groups: an amine, an organosulphate, a sulphonate, a hydroxyl, an ether or a carboxylic acid group, and (c) heating the solution or sol to a temperature of at least 75? C.

9. A process as claimed in claim 8, wherein the zirconium salt is zirconium basic carbonate.

10. A process as claimed in claim 8, wherein in step (a) the solution or sol is heated to a temperature of at least 40? C.

11. A process as claimed in claim 8, wherein the method comprises the step of increasing the pH of the solution or sol by adding a base.

12. A process as claimed in claim 8, wherein in step (c) the heating comprises heating the solution or sol to a temperature of at least 80? C.

13. A process as claimed in claim 8, wherein in step (c) the solution is maintained at that temperature for 1-5 hours.

14. A process as claimed in claim 8 comprising, after step (c), the step of: (d) adding sulphate ions.

15. A zirconium solution or sol as claimed in claim 1, wherein the solution or sol comprises zirconium in an amount of 5-30% by weight based on ZrO.sub.2 equivalent.

16. A zirconium solution or sol as claimed in claim 1, wherein the complexing agent is an alpha hydroxycarboxylic acid.

17. A mixed metal hydroxide, mixed metal oxide, crosslinker, or functional or non-functional binder, formed from a zirconium solution or sol as claimed in claim 1.

18. A zirconium basic sulphate obtainable by the process of claim 14.

19. A process as claimed in claim 8, wherein the solution or sol comprises zirconium in an amount of 5-30% by weight based on ZrO.sub.2 equivalent.

20. A process as claimed in claim 8, wherein the complexing agent is an alpha hydroxycarboxylic acid.

Description

EXAMPLES 1-11

[0042] These examples are all a variation on the first example, Example 1. In Example 1, a stock solution was prepared by dissolving zirconium basic carbonate in nitric acid to give a NO.sub.3:Zr molar ratio of 0.9:1. This stock solution was heated to 60? C. to complete the dissolution. The concentration of this stock solution (quoted as ZrO.sub.2 equivalent on a mass basis) was 26.0%, referred to as ZHN-1 (ie zirconium hydroxy nitrate).

[0043] The required amounts of deionised water, nitric acid, sodium hydroxide, mandelic acid were then added as required for each experiment such that the starting zirconium concentration was 14% (ZrO.sub.2 equivalent on a mass basis).

[0044] A stock solution of mandelic acid (8.0% by weight) was prepared by dissolving commercially available mandelic acid in deionised water. Unless specified below, mandelic acid (Mand) was added in an amount of 1.5 mol % (based on zirconium), the heating rate was 1? C./min, the peak temperature was 94? C. and the dwell time at peak temperature was 2 hours.

[0045] The experimental conditions for Examples 1-11 are set out in Table 1 below, and the results in Table 2 below. In Table 1 below, ZOC refers to zirconium oxychloride. The complexing agent is mandelic acid unless specified otherwise.

[0046] In Table 2, Before refers to the values measured on the initial solution (ie before heated to and dwelling at peak temperature). After refers to the values once this heat treatment has been carried out and cooled to ambient temperature (i.e. room temperature).

TABLE-US-00001 TABLE 1 Complexing Peak Heat Example agent Temp. Rate Dwell ZrO.sub.2 number NO.sub.3:Zr Na:Zr (mol %) (?C.) (?C./min) (hr) (%) 1 1:1 0 5 94 1 2 14 2* 1:1 0 0 94 1 2 14 3 ZOC 0 1.5 94 1 2 14 4 1.3:1 0.3:1 0.5 94 1 2 14 5 1:1 0 1.5 94 1 2 14 6 1:1 0 1.5 85 1 2 14 7 1:1 0 Starch, 1.5 94 1 2 14 8 1:1 0 0.1 94 1 2 14 9 0.8:1 0 1.5 94 1 2 14 10 1:1 0 1.5 94 0.25 2 14 11 2:1 0 1.5 94 1 2 14 * = comparative example

[0047] Additional detail on the preparation of the solutions for the Examples in Table 1 is given below.

Example 1

[0048] 65.38 g of ZHN-1 stock solution was mixed with 2.877 g of 30% HNO.sub.3, 13.03 g of mandelic acid stock solution and 40.14 g of deionised water. This was stirred for 10 mins. 53 cm.sup.3 of this solution was then added to the reaction vessel of a Chandler 5550 Viscometer, pressurised to 500 psi under nitrogen, and with a shear rate of 100 s.sup.?1 (which remained constant throughout the duration of the experiment).

[0049] The temperature was increased from ambient to 60? C. over 15 mins and then dwelled at 60? C. for 10 mins. The temperature was then increased from 60? C. to 94? C. at a rate of 1? C./min followed by a dwell at 94? C. for 2 hrs. Finally, the temperature was reduced to ambient over approximately 20 mins. The in-situ viscosity was recorded during this program.

[0050] The resulting sol was removed from the viscometer vessel and characterised by pH, conductivity, refractive index, density, base-titration and UV-Vis measurements. The original solution (i.e. without being subjected to the above temperature program) was characterised equivalently.

Comparative Example 2

[0051] 65.38 g of ZHN-1 stock solution was mixed with 2.877 g of 30% HNO.sub.3 and 53.17 g of deionised water (ie no complexing agent was added). This was stirred for 10 mins. 53 cm.sup.3 of this solution was then added to the reaction vessel of a Chandler 5550 Viscometer and then processed in exactly the same way as Example 1.

Example 3

[0052] 82.13 g of a zirconium oxychloride solution (20.7% ZrO.sub.2 equivalent, prepared from commercial crystals) was mixed with 3.909 g of the mandelic acid stock solution and 35.39 g of deionised water (ie no complexing agent was added). This was stirred for 10 mins. 53 cm.sup.3 of this solution was then added to the reaction vessel of a Chandler 5550 Viscometer and then processed in exactly the same way as Example 1.

Example 4

[0053] 65.38 g of ZHN-1 stock solution was mixed with 11.51 g of 30% HNO.sub.3, 1.303 g of mandelic acid stock solution, 16.44 g of sodium hydroxide solution (10% by weight) and 26.79 g of deionised water. This was stirred for 10 mins. 53 cm.sup.3 of this solution was then added to the reaction vessel of a Chandler 5550 Viscometer and then processed in exactly the same way as Example 1.

Example 5

[0054] 65.38 g of ZHN-1 stock solution was mixed with 2.877 g of 30% HNO.sub.3, 3.909 g of the mandelic acid stock solution and 49.26 g of deionised water. This was stirred for 10 mins. 53 cm.sup.3 of this solution was then added to the reaction vessel of a Chandler 5550 Viscometer and then processed in exactly the same way as Example 1.

Example 6

[0055] 65.38 g of ZHN-1 stock solution was mixed with 2.877 g of 30% HNO.sub.3, 3.909 g of mandelic acid stock solution and 49.26 g of deionised water. This was stirred for 10 mins. 53 cm.sup.3 of this solution was then added to the reaction vessel of a Chandler 5550 Viscometer and then processed in exactly the same way as Example 1, except that the temperature was increased from 60? C. to 85? C. at a rate of 1? C./min followed by a dwell at 85? C. for 2 hrs.

Example 7

[0056] 65.38 g of ZHN-1 stock solution was mixed with 2.877 g of 30% HNO.sub.3, 0.333 g of soluble starch powder and 52.83 g of deionised water. This was stirred for 10 mins. 53 cm.sup.3 of this solution was then added to the reaction vessel of a Chandler 5550Viscometer and then processed in exactly the same way as Example 1.

Example 8

[0057] 65.38 g of ZHN-1 stock solution was mixed with 2.877 g of 30% HNO.sub.3, 0.261 g of mandelic acid stock solution and 52.91 g of deionised water. This was stirred for 10 mins. 53 cm.sup.3 of this solution was then added to the reaction vessel of a Chandler 5550 Viscometer and then processed in exactly the same way as Example 1.

Example 9

[0058] An analogous solution to the ZHN-1 described above in relation to Examples 1-8 was prepared using the same reagents/conditions but at a NO.sub.3:Zr molar ratio of 0.8:1. The concentration (quoted as ZrO.sub.2 equivalent on mass basis) was 18.0%. 94.44 g of this solution was mixed with 3.909 g of the mandelic acid stock solution and 23.07 g of deionised water. This was stirred for 10 mins. 53 cm.sup.3 of this solution was then added to the reaction vessel of a Chandler 5550 Viscometer and then processed in exactly the same way as Example 1.

Example 10

[0059] 65.38 g of ZHN-1 stock solution was mixed with 2.877 g of 30% HNO.sub.3, 3.909 g of mandelic acid stock solution and 49.26 g of deionised water. This was stirred for 10 mins. 53 cm.sup.3 of this solution was then added to the reaction vessel of a Chandler 5550 Viscometer and then processed in exactly the same way as Example 1, except that a ramp rate of 0.25? C./min was applied from 60? C. to 94? C.

Example 11

[0060] 65.38 g of ZHN-1 stock solution was mixed with 31.65 g of 30% HNO.sub.3, 3.909 g of mandelic acid stock solution and 20.49 g of deionised water. This was stirred for 10 mins. 53 cm.sup.3 of this solution was then added to the reaction vessel of a Chandler 5550 Viscometer and then processed in exactly the same way as Example 1.

TABLE-US-00002 TABLE 2 Free Acidity Peak Conductivity Density Refractive (mmolH.sup.+/ UV-Vis visc. Exp. pH (ms) (g/cm.sup.3) Index gZrO.sub.2) (Abs at 361 nm) (cp) No Before After Before After Before After Before After Before After Before After in-situ 1 0.63 0.52 107 158 1.20 1.20 1.37001 1.37000 7.02 6.69 0.078 1.820 610 2* 0.60 0.52 95 168 1.20 1.20 1.37020 1.37021 6.87 6.50 0.040 0.107 18 3 0.41 0.3 203 233 1.23 1.24 1.37480 15.81 15.98 1.3 4 0.96 0.88 117 176 1.23 1.23 1.37064 1.37444 6.74 6.28 0.050 0.33 2300 5 0.99 0.91 97 162 1.20 1.20 1.37008 1.37066 6.98 6.64 0.056 0.336 21 6 0.87 0.78 99 150 1.20 1.19 1.37444 1.37049 6.90 6.59 0.045 0.176 2.5 7 0.65 0.53 96 154 1.20 1.19 1.37066 1.37037 6.12 5.75 0.030 0.187 6.4 8 0.41 0.3 92 154 1.20 1.20 1.37078 1.37015 6.70 6.26 0.036 0.109 2.7 9 0.9 0.54 35 82 1.19 1.19 1.37924 1.36825 5.25 4.91 0.060 0.176 1600 10 0.33 0.21 99 159 1.21 1.20 1.37138 1.37087 6.73 6.33 0.056 0.576 3.2 11 <0 <0 366 410 1.26 1.26 1.37445 1.38354 15.50 14.55 0.107 2.694 0.91 * = comparative example