The gasket includes a sealing strip comprising a resilient material, the resilient material comprising a chemically exfoliated vermiculite (CEV) component in a proportion of at least 25% w/w of the sealing strip, the said CEV component being at least partially derived from dry CEV, wherein the sealing strip does not include a carrier strip, made by the process of the application of a wet sealing strip material to a forming sheet to form a layer; partially drying the wet sealing strip layer on the forming sheet; removing the layer from the forming sheet; and (d) cutting the layer into strips suitable for use in the formation of a spirally wound gasket.
1. A spirally wound gasket comprising a sealing strip comprising a resilient material, the resilient material comprising a chemically exfoliated vermiculite (CEV) component in a proportion of at least 25% w/w of the sealing strip, the said CEV component being at least partially derived from dry CEV, wherein the sealing strip does not include a carrier strip, made by the process of:
(a) applying a wet sealing material to a forming sheet to form a layer;
(b) partially drying the wet sealing layer on the forming sheet;
(c) removing the partially dried sealing layer from the forming sheet; and
(d) cutting the partially dried sealing layer into strips suitable for use in the formation of a spirally wound gasket.
2. The gasket of claim 1 , wherein the solids content of the wet sealing material prior to the drying step is in the range of 20-70% w/w of the material.
3. The gasket of claim 1 , wherein step (c) is carried out after step (d).
4. The gasket of claim 1 , wherein the solids content of the wet sealing material is in the range 25-60% w/w of the wet material.
5. The gasket of claim 1 , wherein the water content of the partially dried sealing layer during removal from the forming sheet is 3-20% w/w.
6. The gasket of claim 1 , wherein a further drying step is carried out after removal of the partially dried sealing layer from the forming sheet.
7. The gasket of claim 1 , wherein the wet sealing layer is dried at temperatures between 50-135° C.
8. The gasket of claim 1 , wherein the wet sealing material is in the form of a spreadable paste.
9. The gasket of claim 1 , wherein the wet sealing material comprises a CEV component comprising a mixture of dried CEV and CEV in a slurry form.
10. The gasket of claim 1 , wherein the CEV component further comprises a plate-like filling agent.
11. The gasket of claim 10 , wherein the filling agent is present in an amount less than 75% w/w of the sealing strip.
12. The gasket of claim 10 , wherein the plate-like filling agent is thermally exfoliated vermiculite (TEV).
13. The gasket of claim 1 , wherein the wet sealing material is applied to the forming sheet by a spreading technique.
14. The gasket of claim 13 , wherein the spreading technique comprises the application of a doctor blade.
15. The gasket of claim 1 , wherein the resilient material further comprises a hydrolysis resistant polymer.
16. The gasket of claim 15 , wherein the hydrolysis resistant polymer is present in an amount equal to or less than 20% w/w of the sealing strip.
17. A spirally wound gasket comprising a sealing strip comprising a resilient material, the resilient material comprising a chemically exfoliated vermiculite (CEV) component in a proportion of at least 25% w/w of the sealing strip, the said CEV component being at least partially derived from dry CEV, wherein the sealing strip does not include a carrier strip.
18. The gasket of claim 17 , wherein the CEV component further comprises a plate-like filling agent.
19. The gasket according to claim 18 , wherein the filling agent is present in an amount less than 75% w/w of the sealing strip.
20. The gasket of claim 17 , wherein the water content of the sealing strip is less than 20% w/w.
21. The gasket of claim 18 , wherein the plate-like filling agent is thermally exfoliated vermiculite (TEV).
22. The gasket of claim 17 , wherein the resilient material further comprises a hydrolysis resistant polymer.
23. The gasket of claim 22 , wherein the hydrolysis resistant polymer is present in an amount equal to or less than 20% w/w of the sealing strip.