METHODS OF FORMING DRY-TO-THE-TOUCH PEROXIDE COMPOSITIONS

Abstract

Methods of blending liquid peroxide solutions and crystalline or amorphous solid materials to provide a dry-to-the-touch peroxide containing solid materials.

Claims

1. A method of preparing a combination of liquid peroxide and dry solid support comprising spraying a liquid peroxide solution onto a dry silica solid support comprising mixing a hydrophobic or hydrophilic silica powder in a blending unit comprising mixing apparatus and one or more spray nozzles to form a powder wherein the spray nozzles are oriented to minimize impact of the spray on the surfaces of the blending unit or mixing apparatus and the ratio of the liquid peroxide spray droplet size to the silica solid support particle size is between about 0.5 and 10,000 and the blending unit is operated at a Froude number of 1 or less.

2. The method of claim 1, wherein the flow rate of liquid peroxide solution comprises an aqueous solution.

3. The method of claim 1 wherein the liquid peroxide solution comprises hydrogen peroxide, peracetic acid, organic peroxide or combination thereof.

4. The method of claim 1 wherein the concentration of the liquid peroxide solution is from about 0.5% to 70%.

5. The method of claim 1 wherein the concentration of the liquid peroxide solution is from 35% to 70.

6. The method of claim 1 wherein the concentration of the liquid peroxide solution is from 50 to 70%.

7. The method of claim 1, wherein the silica support comprises fumed, pyrogenic silica or precipitated silica or combinations thereof.

8. The method of claim 1, wherein the silica support is in the form of a powder or granules.

9. The method of claim 1, wherein the mixing apparatus comprises a blender operated at a blade tip speed between about 0.5 m/s and about 10.0 m/s.

10. The method of claim 1, wherein the ratio of the liquid peroxide spray droplet size to the silica solid support particle size is between about 0.5 and 10,000.

11. The method of claim 1, wherein the ratio of the liquid peroxide spray droplet size to the silica solid support particle size is between about 0.75 and 3,000.

12. The method of claim 1, wherein the liquid peroxide component flow rate through each one of the one or more nozzles ranges from about 0.5 gpm (1.89 liter per minute) to about 2 gpm (7.57 liters per minute) at 40 psig (276 kPa).

13. The method of claim 1, wherein the one or more spay nozzles are selected from the group consisting of flat spray nozzles, cone spray nozzles, hollow cone spray nozzles, mist/fog nozzles and combinations thereof.

14. The method of claim 1, wherein the blender is operated at a Froude number less than 1 and more than 0.05.

15. The method of claim 14, wherein the blender is operated at a Froude number less than 0.7 and more than 0.075.

16. The method of claim 14, wherein the blender is operated at a Froude number less than 0.5 and more than 0.1.

17. The method of claim 1, wherein the blender is operated at a mixing time between 5 and 45 minutes.

18. The method of claim 17, wherein the blender is operated at a mixing time between 10 to 35 minutes.

19. The method of claim 17, wherein the blender is operated at a mixing time between 15 to 30 minutes.

Description

EXAMPLES

Example 1

[0038] A 75 L double ribbon blender was operated at speed of 60 RPM. A Bete PJ24 90 spray angle nozzle working at high pressure (100 psig or 689 kPa) provided 50% liquid hydrogen peroxide solution at 0.16 gpm (0.60 liter per minute) into 2.5 kg Cab-O-Sil M5 silica to make 8.6 kg product. The spray pattern resulted in spray hitting the blending unit wall. The resulting product contained a large number of agglomerates, and was wet-to-the-touch and had a snowball type texture.

Example 2

[0039] In the same 75 L double ribbon blending unit, a Teejet nozzle, which provided a flat spray pattern, was used with a 50% liquid hydrogen peroxide solution component flow rate of 0.2 gpm (0.76 liter per minute) at 40 psig (276 kPa) into 2.5 kg Cab-O-Sil M5 silica to make 8.6 kg product. The product quality improved but there was still some wet agglomerate formation.

Example 3

[0040] In the same 75 L double ribbon blending unit, a Teejet nozzle, which provided a flat spray nozzle with a flow rate of about 0.067 gpm (0.25 liter per minute) at a pressure under 40 psig (276 kPa) into 2.5 kg Cab-O-Sil M5 silica led a total of 8.6 kg of good quality product, dry-to-the-touch powder, with minimal agglomerate formation.

Example 4

[0041] In a commercial size 1273 L paddle blender, 139 pounds (63 kg) of silica (Cab-O-Sil M5 available from Cabot Corp.) was loaded into the blender which occupied about 90% of the blender volume. The spray nozzles were directly outside of the silica. The blender was operated at a speed of 20.5 RPM, using a series of 5 TeeJet flat nozzles with a flow of 0.4 gpm (1.5 liter per minute) at a pressure of 30 psig (207 kPa), placed in a way that the spray patterns did not overlap or hit the blender sidewalls. A good quality product, dry-to-the-touch powder, with no agglomerate formation resulted. The Froude number was calculated to be 0.21, which is considerably less than 1 which literature states is ideal for mixing powers and liquid. The tip speed of the paddles was about 1 m/s. The blender was turned on with no discernable notice of dust in the dust collector. The 50.1% hydrogen peroxide addition occurred over 19 minutes and a total of 366 pounds (166 kg) of hydrogen peroxide was added, though it was calculated that 357 pounds (162 kg) actually went into the blender as 9 pounds (4 kg) filled the feed lines. After the hydrogen peroxide was added, the blender was allowed to blend for an additional 5 minutes with the chopper turned on for 5 seconds every minute. The resulting product was a free flowing dry-to-the-touch powder and was analyzed to have 36% hydrogen peroxide incorporated into the silica.