Modified, precipitated alumino silicate pigments

Abstract

Novel alkali aluminum silicate particulates, modified with and containing a chemically bound alkaline earth metal, are disclosed. The alumino silicate pigments contain an alkaline earth metal, preferably calcium or magnesium, in addition to an alkali metal, such as sodium. In chemical composition, the pigments contain oxides of the alkaline earth metal, the alkali metal, aluminum and silicon and are distinguishable from co-precipitates. The pigments are prepared by introducing dilute solutions of an alkali silicate and an aluminum salt of a mineral acid into an agitated aqueous receiving medium containing an alkaline earth salt or hydroxide. The pH of the fluid reaction medium may be controlled to form finely divided precipitated particulates having improved properties and which may be used as pigments in paper, paint, rubber, inks, plastics, and the like.

What is claimed is: .[.1. A finely divided, precipitated, white powdery composition comprising chemically bound oxides of magnesium, sodium, aluminum, and silicon in a uniform matrix substantially all of the particles of which are less than 1 micron in diameter, the molar ratio of SiO 2  to Na 2  O being at least about 4 to 1 and the molar ratio of Na 2  O to Al 2  O 3  being from about 0.8 to 1.4:1, said magnesium oxide being present in an amount of from about 0.1 to 8 percent based on the dry weight of the composition; said composition having a specific gravity of 2.0 to 2.4; said composition further having an alkalinity in the range of from about 40-60 meg/100 g; a LOI in the range of from about 6-8.5% by weight; an oil absorption in the range of from about 110 to 145 cc/100 g and a surface area in the range of from about 50 to 120 M 2  /g..]. .[.2. A finely divided precipitated, white powdery composition comprising chemically bound oxides of calcium, sodium, aluminum, and silicon in a uniform matrix substantially all of the particles of which are less than 1 micron in diameter, the molar ratio of SiO 2  to Na 2  O being at least about 4 to 1 and the molar ratio of Na 2  O to Al 2  O 3  being from about 0.8 to 1.4:1, said calcium being present in an amount of from about 0.1 to 8 percent based on the dry weight of the composition having a specific gravity of 2.0 to 2.4; said composition further having an alkalinity in the range of from about 40-60 meg/100 g; a LOI in the range of from about 6-8.5% by weight; an oil absorption in the range of from about 110 to 145 cc/100 g and a surface area in the range of from about 50 to 120 M 2  /g..]. .[.3. A finely divided, precipitated, white powdery composition comprising chemically bound oxides of barium, sodium, aluminum, and silicon in a uniform matrix substantially all of the particles of which are less than 1 micron in diameter, the molar ratio of SiO 2  to Na 2  O being at least about 4 to 1 and the molar ratio of Na 2  O to Al 2  O 3  being from about 0.8 to 1.4:1, said barium being present in an amount of from about 0.1 to 8 percent based on the dry weight of the composition having a specific gravity of 2.0 to 2.4; said composition further having an alkalinity in the range of from about 40-60 meg/100 g; a LOI in the range of from about 6-8.5% by weight; an oil absorption in the range of from about 110 to 145 cc/100 g and a surface area in the range of from about 50 to 120 M 2  /g..]. .[.4. The composition in accordance with claim 1, said composition further comprising the oxides of magnesium, sodium, aluminum, and silicon precipitated in intimate association with finely divided particles of precipitated silica..]. .[.5. The composition in accordance with claim 2, said composition further comprising the oxides of calcium, sodium, aluminum, and silicon precipitated in intimate association with finely divided particles of pre-precipitated silica..]. .[.6. The composition in accordance with claim 3, said composition further comprising the oxides of barium, sodium, aluminum, and silicon precipitated in intimate association with finely divided particles of pre-precipitated silica..]. .Iadd. 7. A finely divided precipitated, white powdery composition comprising chemically bound oxides of an alkaline earth metal selected from the group consisting of magnesium, calcium, barium, or combinations thereof; sodium; aluminum; and silicon in a uniform matrix substantially all of the particles of which are less than 1 micron in diameter, the molar ratio of SiO 2  to Na 2  78 O being at least about 4 to 1 and the molar ratio of Na 2  O to Al 2  O 3  being from about 0.8 to 1.4:1, said alkaline earth metal oxide being present in an amount of from about 0.1 to 8 percent based on the dry weight of the composition having a specific gravity of 2.0 to 2.4; said composition further having a LOI in the range of from about 6.38 to 9.7% by weight; an oil absorption in the range of from about 108 to 170 cc/100 g and a surface area in the range of from about 59 to 176 M 2  /g. .Iaddend..Iadd. 8. The composition in accordance with claim 7, said composition further comprising the oxides of an alkaline earth metal, sodium, aluminum, and silicon precipitated in intimate association with finely divided particles of pre-precipitated silicate. .Iaddend..Iadd. 9. The composition of claim 7 wherein said alkaline earth metal is magnesium. .Iaddend..Iadd. 10. The composition of claim 9 wherein said composition has an oil absorption in the range of from about 108 to 156 cc/100 g. .Iadd. 11. The composition of claim 7 wherein said alkaline earth metal is calcium. .Iadd. 12. The composition of claim 11 wherein said composition has a LOI in the range of about 8.5 to 9.3% by weight. .Iaddend..Iadd. 13. The composition of claim 12 wherein said composition has an oil absorption in the range of from about 132 to 170 cc/100 g. .Iaddend..Iadd. 14. The composition of claim 13 wherein said composition has a surface area in the range of from about 105 to 111 M 2  /g. .Iaddend..Iadd. 15. The composition of claim 7 wherein said alkaline earth metal is barium. .Iaddend..Iadd. 16. The composition of claim 15 wherein said composition has a LOI of about 9.0% by weight. .Iaddend..Iadd. 17. The composition of claim 16 wherein said composition has an oil absorption in the range of about 160 cc/100 g. .Iaddend..Iadd. 18. The composition of claim 17 wherein said composition has a surface area of about 112 M 2  /g. .Iaddend..Iadd. 19. The composition of claim 7 wherein said alkaline earth metal is a combination of magnesium and calcium. .Iaddend..Iadd. 20. The composition of claim 19 wherein said composition has a LOI of about 8.9% by weight. .Iaddend..Iadd. 21. The composition of claim 20 wherein said composition has an oil absorption of about 156 cc/100 g. .Iaddend..Iadd. 22. The composition of claim 21 wherein said composition has a surface area of about 130 M 2  /g. .Iaddend. .Iadd. 23. A finely divided precipitated, white powdery composition comprising chemically bound oxides of an alkaline earth metal selected from the group consisting of magnesium, calcium, barium, or combinations thereof; sodium; aluminum; and silicon in a uniform matrix substantially all of the particles of which are less than 1 micron in diameter, the molar ratio of SiO 2  to Na 2  O being at least about 4 to 1 and the molar ratio of Na 2  O to Al 2  O 3  being from about 0.8 to 1.4:1, said alkaline earth metal oxide being present in an amount of from about 0.1 to 8 percent based on the dry weight of the composition having a specific gravity of 2.0 to 2.4. .Iaddend..Iadd. 24. The composition of claim 23 wherein said alkaline earth metal is magnesium. .Iaddend..Iadd. 25. The composition of claim 23 wherein said alkaline earth metal is calcium. .Iaddend..Iadd. 26. The composition of claim 23 wherein said alkaline earth metal is barium. .Iaddend..Iadd. 27. The composition of claim 23 wherein said alkaline earth metal is a combination of magnesium and calcium. .Iaddend..Iadd. 28. The composition of claim 23 wherein said composition has a LOI in the range of from about 6.38 to 9.7% by weight. .Iaddend..Iadd. 29. The composition of claim 25 wherein said composition has a LOI in the range of about 8.5 to 9.3% by weight. .Iaddend..Iadd. 30. The composition of claim 23 wherein said composition has an oil absorption in the range of from about 108 to 170 cc/100 g. .Iaddend..Iadd. 31. The composition of claim 24 wherein said composition has an oil absorption in the range of from about 108 to 156 cc/100 g. .Iaddend. .Iadd. 32. The composition of claim 25 wherein said composition has an oil absorption in the range of from about 132 to 170 cc/100 g. .Iaddend..Iadd. 33. The composition of claim 23 wherein said composition has a surface area of from about 59 to 176 M 2  /g. .Iaddend..Iadd. 34. The composition of claim 25 wherein said composition has a surface area in the range of from about 105 to 111 M 2  /g. .Iaddend..Iadd. 35. The composition of claim 23 wherein said composition has a pigment (Elrepho) brightness of from about 90.4 to 94.5. .Iaddend..Iadd. 36. The composition of claim 23 wherein said composition has a 20% pH of from about 10.1 to 11.3. .Iaddend..Iadd. 37. The composition of claim 23 wherein said composition has a 325 screen residue of from about 0.04 to 5.3%. .Iaddend..Iadd. 38. The composition of claim 23 wherein said composition has a Valley Abrasion of from about 1.5 to 10.9 mg. loss. .Iaddend..Iadd. 39. The composition of claim 23 wherein said composition has a pour density of from about 8.6 to 12.0 lb./ft 3 . .Iaddend. .Iadd. 40. The composition of claim 23 wherein said composition has a pack density of from about 17.5 to 25.0 lb./ft 3 . .Iaddend..Iadd. 41. The composition of claim 23 wherein said composition has a percentage retention in fine paper of from about 42 to 57%. .Iaddend..Iadd. 42. The composition of claim 23 wherein said composition has a percentage of solids in its wet cake of from about 23.6 to 29.7% solids. .Iaddend..Iadd. 43. The composition of claim 23 wherein said composition has a TAPPI Brightness in fine paper of from about 87.1 to 90.2. .Iaddend. .Iadd. 44. The composition of claim 23 wherein said composition has a TAPPI Opacity in fine paper of from about 79.3 to 89.0. .Iaddend..Iadd. 45. The composition of claim 23 wherein said composition consists essentially of particles substantially all of which are less than 0.5 microns in diameter after milling. .Iaddend..Iadd. 46. The composition of claim 23 wherein said composition consists essentially of particles at least about 97 percent of which are less than 0.05 microns in diameter after milling. .Iaddend..Iadd. 47. The composition of claim 23 wherein said composition may be represented by the following formula: 
       
         1.3 Na.sub.2 O.1.0 Al.sub.2 O.sub.3.1.2 MgO.14.3 SiO.sub.2.4.3 H.sub.2 O. .Iaddend..Iadd. 48. The composition of claim 23 wherein said composition has a LOI in the range of from about 6.38 to 9.7% by weight; an oil absorption in the range of from about 108 to 170 cc/100 g; a surface area in the range of from about 59 to 176 M.sup.2 g; and a pigment (Elrepho) brightness of from about 90.4 to 94.5. .Iaddend..Iadd. 49. The composition of claim 48 wherein said composition has a 325 screen residue of from about 0.04 to 5.3%. .Iaddend..Iadd. 50. The composition of claim 49 wherein said composition has a Valley Abrasion of from about 1.5 to 10.9 mg. loss. .Iaddend..Iadd. 51. The composition of claim 50 wherein said composition has a pour density of from about 8.6 to 12.0 lb./ft.sup.3. .Iaddend..Iadd. 52. The composition of claim 51 wherein said composition has a pack density of from about 17.5 to 25.0 lb./ft.sup.3. .Iaddend..Iadd. 53. The composition of claim 52 wherein said composition consists essentially of particles substantially all of which are less than 0.5 microns in diameter after milling. .Iaddend. .Iadd. 54. The composition of claim 53 wherein said composition consists essentially of particles at least about 97 percent of which are less than 0.05 microns in diameter after milling. .Iaddend..Iadd. 55. The composition of claim 54 wherein said composition has a TAPPI Brightness in fine paper of from about 87.1 to 90.2. .Iaddend..Iadd. 56. The composition of claim 55 wherein said composition has a TAPPI Opacity in fine paper of from about 79.3 to 89.0. .Iaddend..Iadd. 57. The composition of claim 56 wherein said composition has a percentage retention in fine paper of from about 42 to 57%. .Iaddend..Iadd. 58. The composition of claim 57 wherein said composition has a 20% pH of from about 10.1 to 11.3. .Iaddend..Iadd. 59. The composition of claim 58 wherein said composition has a percentage of solids in its wet cake of from about 23.6 to 29.7% solids. .Iaddend..Iadd. 60. The composition of claim 59 wherein said alkaline earth metal is magnesium. .Iaddend..Iadd. 61. The composition of claim 60 wherein said composition has an oil absorption in the range of from about 108 to 156 cc/100 g. .Iaddend. .Iadd. 62. The composition of claim 61 wherein said composition may be represented by the following formula: 
       
       
         1.3 Na.sub.2 O.1.0 Al.sub.2 O.sub.3.1.2 MgO.14.3 SiO.sub.2.4.3 H.sub.2 O. .Iaddend. .Iadd. 63. The product of claim 23 wherein the product is produced by introducing a dilute aqueous solution of an alkali silicate and a dilute aqueous solution of an aluminum salt into an agitated aqueous receiving medium containing an alkaline earth metal salt or hydroxide, with at least some of the alkali silicate and aluminum salt solutions being simultaneously introduced into said receiving medium. .Iaddend..Iadd. 64. The product of claim 63 wherein said aqueous receiving medium contains an alkaline earth metal salt and the pH of the reaction solution is maintained between about 8 and 12. .Iaddend.