Area weight uniformity flexible graphite sheet material
View Patent ↗A process for enhancing the expansion of intercalated graphite flake is presented. The process includes annealing the graphite flake at a temperature of at least about 3000° C. prior to intercalation and intercalating in the presence of a lubricious additive.
1. A process for preparing flexible graphite sheet having a thickness of less than 3 mils and a tensile strength of at least about 750 lbs/in 2 , comprising:
(1) treating natural graphite flakes with an intercalant comprising a lubricious additive to provide intercalated graphite flakes;
(2) exfoliating the intercalated graphite flakes to form exfoliated graphite flakes; and
(3) thereafter forming the exfoliated graphite flakes into a flexible graphite sheet.
2. The process of claim 1 wherein the flexible graphite sheet is no more than 2 mils thick.
3. The process of claim 1 , which further comprises annealing the graphite flakes at a temperature of at least about 3000° C. prior to treatment with the intercalant.
4. The process claim of claim 3 wherein the annealing is performed for a period in excess of 1 hour.
5. The process of claim 4 wherein the annealing is performed in an inert environment.
6. The process of claim 1 wherein the lubricious additive is present in the intercalant at a level of at least about 1.4 pph.
7. The process of claim 6 wherein the lubricious additive comprises a long chain hydrocarbon or long chain hydrocarbon group.
8. The process of claim 7 wherein the lubricious additive comprises an oil.
9. The process of claim 7 wherein the lubricious additive comprises a hydrocarbon having at least 10 carbons.