Problem in EPDM based rollers

[nightrain]

Hello.

Currently i am having problem of my EPDM rolls, the layers of the rubbers are separating. i have purchased a PF resin named Durez 19900.

I would like to know if this is the right solution for my problem.

Also PF resin as tackifying agent, do i need to add HMT ?

Here is the formula i have now

EPDM (60 MV, 70 % ethylene, 4.5 % enb) = 100 phr
Zinc oxide = 5 phr
Stearic Acid = 1 phr

Hard clay = 130 phr
N 550 Carbon black = 50 phr
Calcium carbonate 1500 mesh = 20 phr
Parafinic oil = 40 phr

Sulphur = 1,5 phr
MBTS = 1,5 phr
TMTD = 0,5 phr
ZDBC = 2 phr

 

[GrahamBennett]

If you add HMT to your formulation there will be a chemical reaction between it and the PF resin that will result in a significant increase in hardness.

forumtowers.com

 

[nightrain]

I see... do you have starting recommebdation on how many phr the pf resin as tackifier ?

Or is there any better option ?

 

[GrahamBennett]

I would be inclined to use between 1 and 1.5phr of KORESIN rather than the normal lower cost grades of PF resins (you need more than 5phr of these for not even the same level of tackiness).

forumtowers.com

 

[tom1953]

Another thought is to replace some of the 60 viscosity EPDM with lower viscosity EPDM (keeping the E/P ratio and ENB as similar as possible), which may improve flow of the rubber.
How are you vulcanizing? In a steam or hot air autoclave? If so, try increasing the amount of time at <110°C to give the rubber more time to soften and flow together before curing (keeping the pressure high with the hot air/electric autoclave; if it's steam, the pressure and temp are related so low steam pressure gives low temperature). Also, make sure you've got a good pressure wrap on the roller.

Tom J.