How to Obtain Small Natural Rubber Particles for Textile Impregnation?

Manufacturer: We are manufacturing textile and similar products treated with natural rubber latex. We understand that one of the criteria of good penetration and impregnation of the rubber into the textile is the rubber particle size in the latex i.e. we need small rubber particles.

We have been told that in the normal centrifuged latex concentrates, the inherently smaller rubber particles of the latex have been removed by the centrifugation process. My question is how and where do we obtain such small sized rubber particles which are originally present in the latex?


John Woon (Senior Latex Consultant): Good question! Though it is possible it is costly to recover the small sized rubber particles from the skim after the centrifugation of field latex to obtain the concentrated latex.

Fortunately all is not lost because latex concentrates made by evaporation process are commercially available from Revertex Malaysia (Synthomer). In the evaporation process, only water is removed from the latex hence the inherently present small rubber particles are not removed, unlike the centrifuged latex.

Also, these evaporated latex concentrates have excellent mechanical and compounding stability besides having excellent penetrating property. They are available with 68% and 73% TSC.

How to Minimize Copper Staining While Maintening Dithiocarbamates in the Compound Fromulations

Manufacturer: We are a medium sized factory manufacturing latex thread and other dipped products. In one of our products we would like to minimize copper staining. We also want good heat resistance. However we do not want to replace dithiocarbamate in your latex compound. What shall we do?

John Woon (Senior Latex Consultant): It is not easy to prevent copper staining without removing dithiocarbamates from your latex compound formulations. However, I have the following suggestion to control the staining:

1) Try reducing the level of dithiocarmate to the very minimal while adding a thiazole (ZMBT) as the main accelerator. The reduced level of dithiocarbamate is such that it still gives you reasonable rate of vulcanization and physical properties of the final products.

2) If you are using ZDEC, replace it with ZDBC as the latter has lesser tendency to cause migration staining.

As for heat resistance, you can try sulphur donors such as TMTD, DPTT or Morpholine disulphide in conjunction with thiazoles.