Rubber latex films having improved tear resistance
A method of making a rubber latex comprises providing a rubber latex and adding to the latex a solution of a reinforcing agent. Further, a method of making a reinforced rubber latex film comprises providing a rubber latex, adding to the latex a solution of a reinforcing agent, then forming a film from the latex. There is also provided a rubber latex comprising a solution of a reinforcing agent, which is preferably a solution of a water-soluble silicate. Rubber latex films and articles made therefrom are also provided.
1. A method of making a reinforced rubber latex film, which method comprises providing a rubber latex, adding to the latex a solution of a reinforcing agent, wherein said solution of a reinforcing agent is a water soluble silicate then forming a film from the latex, wherein the amount of reinforcing agent in the latex is from 0.1 to 10 parts per hundred rubber (pphr).
2. The method according to claim 1 wherein the silicate is sodium silicate.
3. The method according to claim 2 wherein the silicate is sodium metasilicate or sodium meta-disilicate.
4. The method according to claim 1 wherein the pH of the solution added to the latex is about pH 10 or above.
5. The method according to claim 1 wherein the rubber latex is prevulcanised before addition of the solution of reinforcing agent.
6. The method according to claim 1 wherein, after addition of the solution of reinforcing agent, the pH of the latex is reduced below its initial value.
7. The method according to claim 1 wherein the amount of reinforcing agent is 2 pphr or above.
8. The method according to claim 1 wherein the solution is a 40-60% w/w aqueous solution of a water-soluble silicate.
9. The method according to claim 1 wherein the rubber latex film is formed by dipping, casting or electrostatic spraying.
10. A rubber latex suitable for forming a latex film, said latex comprising a solution of a reinforcing agent wherein said solution of a reinforcing agent comprises a water soluble silicate wherein the amount of reinforcing agent in the latex is from 0.1 to 10 parts per hundred rubber (pphr).
11. The latex according to claim 10 which latex is prevulcanised.
12. The rubber latex film formed from a latex according to claim 10 .
13. A rubber article formed of a rubber latex film according to claim 12 .
14. A condom formed of a rubber latex film according to claim 12 .
15. A method comprising using a latex according to claim 10 in the manufacture of reinforced rubber films and articles.
16. A method comprising using a water-soluble silicate as a reinforcing agent for rubber latex films and articles made therefrom wherein the amount of reinforcing agent in the rubber latex film is from 0.1 to 10 parts per hundred rubber (pphr).