Rubber,mixing-hardnes?
Rubber,mixing-hardnes?
(OP)
Hello,
We have problem with rubber hardness it is sometimes higher and sometimes lower with same raw materials, so could somebody tell me how can we encrease hardness during mixing step in our production. Does the odrder of adding raw matterials has some infulance of the hardness or temperature of mixer or something else. Of course I know that hardness is function of filler properties and quantity.
Thank you.
We have problem with rubber hardness it is sometimes higher and sometimes lower with same raw materials, so could somebody tell me how can we encrease hardness during mixing step in our production. Does the odrder of adding raw matterials has some infulance of the hardness or temperature of mixer or something else. Of course I know that hardness is function of filler properties and quantity.
Thank you.





RE: Rubber,mixing-hardnes?
RE: Rubber,mixing-hardnes?
We have good hardnes when we mix the whole batch in the open mill , but we have 2 shores lower hardnes when we mix it in the internall mixer? And we also have problems with some types of formulations with lower hardness on the internall mixer?
Regards,
RE: Rubber,mixing-hardnes?
What I meant to tell you was that a 2 pass mix in an internal mixer (banbury) is more liable to weighing errors than a one pass open mill mix. With a mill mix it is easy to see the iunincorporated materials in the pan, sweep them up and add them to the batch--you should not "loose" anything.
If you are getting 2 points lower durometer on this compound mixed in a banbury then you are probably losing pigments due to 1)a worn out mixer, 2)incorrect material addition, or 3) mix cycle (time) or a combination of all three--carbon black or other pigment will be visible when the batch is discharged. Are you getting a lower sp. grav. on the mixer batch vs. the mill batch?? If you run rheometers is their a difference in the curves from mill mix and banbury??
You haven't provided enough info to make a thorough analysis. If you are running both high and low durometer on different compounds I am sure I can heelp you correct this but I would need the formula and mix spec details for each problem compound.
KEL2149@yahoo.com cell.. 513.312.0457
RE: Rubber,mixing-hardnes?
Thank you for the answer.
I'm on the holliday now, but after I'll check reo curves and spec gravity .
What does it mean "worn out mixer"?
Thank you for the lot off information and of course for your time.
Regards,
RE: Rubber,mixing-hardnes?
What part of the world are you located in? Hope ur holdiay is enjoyable