The present invention is directed to a process for the treatment of talc, comprising the steps of (a) providing a talc having a first brightness value B1, measured according to ISO 2469, and forming a suspension of the talc in a liquid phase, the liquid phase of the suspension comprising at least on
The present invention is directed to a process for the treatment of talc, comprising the steps of (a) providing a talc having a first brightness value B1, measured according to ISO 2469, and forming a suspension of the talc in a liquid phase, the liquid phase of the suspension comprising at least one organic solvent, (b) delaminating and/or reducing the weight median particle size d50 of the talc, wherein the treated talc has a brightness value B2, measured according to ISO 2469, and B2≧B1.
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1. A process for the treatment of talc, the process comprising the steps of: (a) forming a suspension of a talc in a liquid phase, the liquid phase of the suspension comprising hexane, octane, or a mixture thereof, wherein the talc: (i) has a purity of 98 wt % or less and a specific surface area ran
1. A process for the treatment of talc, the process comprising the steps of: (a) forming a suspension of a talc in a liquid phase, the liquid phase of the suspension comprising hexane, octane, or a mixture thereof, wherein the talc: (i) has a purity of 98 wt % or less and a specific surface area ranging from about 2 to about 12 m2/g, measured by the BET method according to ISO 9277 using nitrogen;(ii) has an initial weight median particle size (d50), measured by laser diffraction/scattering particle size analysis according to the Malvern method, ranging from about 15 to about 40 μm;(iii) has a first brightness value B1 of 80% or less, measured according to ISO 2469; and(iv) includes impurities selected from the group consisting of iron sulphide, carbon, or any mixture thereof, and(b) increasing the specific surface area of the talc by about 100% to about 500% relative to the specific surface area of the talc provided in step (a) in the liquid phase to produce a treated talc, and decreasing the d50 of the talc into the range of about 7 to about 30 μm, wherein the treated talc has a brightness value B2, measured according to ISO 2469, and B2 is greater than B1 by at least 0.3%. 2. The process according to claim 1, wherein the talc provided in step (a) is talc from Sotkamo (Finland). 3. The process according to claim 1, wherein the talc content of the suspension is within the range of 5 to 25 wt %, based on the total weight of the suspension. 4. The process according to claim 1, wherein the at least one organic solvent is present in an amount of at least 50 wt %, based on the weight of the liquid phase of the suspension. 5. The process according to claim 4, wherein the liquid phase of the suspension consists of the organic solvent. 6. The process according claim 1, wherein the liquid phase of the suspension further comprises water. 7. The process according to claim 6, wherein the water and the organic solvent form an emulsion. 8. The process according to claim 1, wherein step (b) comprises grinding of the talc suspension. 9. The process according to claim 8, wherein the talc suspension is ground in a ball mill. 10. The process according to claim 1, wherein step (b) comprises treatment of the talc suspension in a homogeniser. 11. The process according to claim 10, wherein the homogeniser is a high pressure homogeniser. 12. The process according to claim 1, further comprising a step (c) wherein the talc content of the suspension is increased by removal of the liquid phase. 13. The process according to claim 12, wherein the liquid phase is removed until dryness of the treated talc. 14. The process according to claim 12, wherein step (c) comprises thermal treatment, filtration, centrifugation, evaporation at reduced pressure, or any combination thereof. 15. The process according to claim 1, wherein the difference between the brightness B2 of the treated talc and the brightness B1 of the talc provided in step (a), expressed as (B2−B1), is at least 0.5%. 16. The process according to claim 1, wherein step (b) is carried out for at least 1 hour. 17. The process according to claim 1, wherein the talc comprises particles that are larger than 100 μm. 18. The process according to claim 1, wherein the talc comprises macrocrystalline talc particles. 19. The process according to claim 1, wherein the talc comprises microcrystalline compact talc particles. 20. The process according to claim 1, wherein the initial weight median particle size d50 of the talc ranges from about 20 μm to about 30 μm, and is decreased to a size ranging from greater than 9 μm up to 23 μm.
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이 특허에 인용된 특허 (7)
Weber Kenneth E. (Pacific Palisades CA), Beneficiated talcs.
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