anti static shoe formulation

[henry_121979]

can somebody please help me to develop/formulate an anti static shoe formulation,im new in this kind of industry,we manufactured shoe sole/pvc compounding.im just 1 year in this kind of industry,so i need someones idea,opinion to where i will start.i already have an anti static agent,do i need to use an coupling agent?we use PVC resin K65.can somebody give me guidelines on these.because i know there are many of you here that are professional on this.pls...tnx

[Skip]

Henry,

The following information comes from "Handbook of PVC Formulating", edited by Edward J. Wickson, Wiley Interscience.1993, Chapter 17, "Antistats", by Richard F. Grossman, p.498.

Static Resistant Shoe Soles

PVC -----------------------------------------100
NBR Elastomer-------------------------------30
DINP------------------------------------------80
ESO-------------------------------------------10
CaCO3 Filler----------------------------------6
Stearic Acid----------------------------------1
Calcium Stearate----------------------------0.2
Tin Stabilizer--------------------------------2
Ethoxylated Amine Antistat---------------6

Surface resistivity with the antistat was 10 (to the 7th) ohms, providing protection from spark discharge resulting from static buildup. Surface resistivity without the amine antistsat was 10(to the 9th) ohms.
Hope this gives at least a starting point formulation.

[Len]

The K values of your resin is a little low, from my perspective. Is there any reason why you would not use a 68 or 70 K resin in this application? I would also pick a resin that had good dry up characteristics for better plasticizer absorption. And, do not add the NBR to the mixer until you have successfully absorbed all that DINP, or you'll have the biggest mess of your short career!

NBR has a greater affinity for plasticizer than the PVC resin. It will preferentially pull the oil away from the PVC and it will turn into a sticky, gummy mess in the HI mixer or ribbon blender.
Ingredients.................................PHR...Mixing sequence
PVC -----------------------------------------100 1.) Resin added at RT
NBR Elastomer-------------------------------30 Drop to cooler, Cool to 40C. Then add NBR at the cooler.
DINP------------------------------------------80 3.) Plasticizer and ESO added at 60C.
ESO-------------------------------------------10
CaCO3 Filler----------------------------------6 4.) Filler added at 100C. or after plasticizer dry up.
Stearic Acid----------------------------------1 5.) Lubricants and Anti-stat added after dry up.
Calcium Stearate----------------------------0.2
Tin Stabilizer--------------------------------2 2.) Tin Stabilizer added next. Blend.
Ethoxylated Amine Anti-stat---------------6

This is a good starting point batch sequence, using a high intensity (HI) blender w/ a cooler. Mix thoroughly after adding NBR to your cooler to give a uniform/homogeneous blend. You are making a PVC/NBR alloy. It's a little tricky, because the NBR powder will fuse in the mixer if it's mishandled.

Len

[Skip]

Len, thanks for that blend sequence------I had forgotton the affinity of NBR for plasticizers!!

[Len]

Skip,

That was my area of Technical Service for several years.

Each of us has his own special gift, and you know this was meant to be.
So, if you don't underestimate you, I swear I won't underestimate me,my brother.

Dear Landlord by Joe Cocker

Long live rock!

Len

[henry_121979]

im so thankful guys because somewhere out there is trying to help me in my formulation.even were far apart,i still have concerns,is it possible not to use nbr for anti static?can i just use anti static agent and coupling agent only w/out nbr?

[greg]

What great detailed answers guys, nice work, we're fortunate to have your participation

[Len]

Thanks, Greg.

Henry,

The NBR is an elastomer, very compatible w/ f-PVC, and gives great oil and solvent resistance. You can eliminate it w/ out effecting antistatic properties, but you must adjust you plasticizer level upward to compensate for the NBR you've taken out. At the 80 phr level of your DINP you might add an extra 5 to 10 phr of plasticizer to compensate if the 30 phr of NBR is removed.

The NBR is about 50% efficient as a plasticizer, but that only hold true a low overall plasticizer level, say 30 to 50 phr of DINP. At 80 PHR of DINP the loss of 30 phr of NBR will not drop your hardness very much. If you were at a 40 phr level of DINP and you removed 30 phr of NBR, you'd have to add 15-20 phr of DINP to compensate for the removing 30 phr of NBR rubber.

I hope this is helpful.

Len

[henry_121979]

tnx very much len!


are ESO and Chlorinated paraffin considered as secondary plasticizers?are they counted as plasticizer also?i know that eso also support the chain bonding of pvc resin and dop,we use dop right now but before we used dinp, and CP is a flame retardant,but does the two of them considered as plasticizer?im sorry guys if i have so many questions,i just wanna work on this thing,because i came from cosmetics industry before,so i guess its too far from pvc compounding.i am using about 60-65 phr of dop,when you say plasticizer,is it dop itself only or along with eso and cp?

Hope guys you could always help and guide me...

[Skip]

Plasticizer efficiency is the determinant for classifying "primary" and "secondary" plasticizer types----and that efficiency rating is based on a comparison of flexibility/hardness properties of a PVC formulation with the plasticizer in question to a PVC formulation with 50 parts of DOP--the so called "standard" formulation.

ESO and Chlorinated Paraffin are secondary (less efficient) plasticizers, while DINP,DOP,DIDP or any other phthalate ester are primary (more efficient) plasticizers. ESO functions also as a synergistic stabilizer with the primary stabilizer----ESO can absorb HCl from degrading PVC, forming a Chlorohydrin. Removing HCl is important because it is a PVC degradation catalyst ,causing more "unzippering" of HCl. CP does have flame retardant properties----but not sure why you'd want it in shoe soles!

At any rate, the total plasticizer level will affect degree of hardness or flexibility, with changes in primary plasticizers having a greater effect than changes in secondary plasticizers.

Perhaps the best overall reference on the subject of plasticizers is "The Technology of Plasticizers" by J.K.Sears and J.R. Darby, published by John Wiley & Sons, 1982. I highly recommend it to anyone serious about their plasticizer choices.

[Len]

Skip, I have a copy which was handed to me by J. K. Sears.

Len

[henry_121979]

tnx len and skip!!


i've read something on the article that in formulating an anti static shoe sole,that theres a need to use a coupling agent to bind the organic and inorganic matters,is it possible not to use coupling agent like organo titanate? Here are my raw matls in shoe sole.

1.pvc resin-K65
2.DOP
3.ESO
4.CP
5.liquid stabilizer(Ba-cd-zn)
6.CaCO3
7.Powder stabilizer
8.lubricant

I dont use NBR,just pure pvc resin,can i just add the anti static agent alone in my formulation without coupling agent and NBR? because they tried it last year,they just add the anti static agent but when subjected to injection for molding of shoe sole,it didnt work out.the sole didnt mold.when i read your recomenmdation(skip and len) about the blending sequence,i suspected that our mixing process was the problem,because what they did was,they just put all the raw mtals in just single charging,they charge first the pvc resin then dop then stabilizer and so on and so fourth,simultaneously.

tnx again guys and hope u can provide me any info about my concerns.tnx!!!

[Len]

Henry,

A coupling agent should not be necessary in your formulation. Compatibility w/ your filler should be just fine w/ out titanate.

Ingredients.................................PHR...Mixing sequence
PVC -----------------------------------------100........1.) Resin added at RT
DINP------------------------------------------85-90....3.) Plasticizer, Anti-stat, and ESO added at 60C.
ESO-------------------------------------------10
CaCO3 Filler----------------------------------6......4.) Filler added at 100C. or after plasticizer dry up.
Stearic Acid----------------------------------1......5.) Lubricants added after dry up, last.
Calcium Stearate----------------------------0.2
Tin Stabilizer--------------------------------3......2.) Ba/Zn Stabilizer added next. Blend.
Ethoxylated Amine Anti-stat---------------6

I bumped your plasticizer level up to compensate for the removal of NBR. And, the anti-stat is probably a plasticizer/antistat blend, so I treated it like plasticizer in the addition sequence. When I speak of plasticizer I'm referring to DOP, DINP, DIDP, ESO, chlorinated Paraffin, etc. The later is a secondary plasticizer, as Skip pointed out.

You will not have great oil and/or solvent resistance w/ this formulation, but you may not need it. An increased K value would help that somewhat.

Do not under estimate your experience in the cosmetic business. Formulation in PVC is like cosmetics in that the end product is effected by the ingredients and sensitive to component properties, level and mixing sequence. One can not put on shoes before ones socks. Each component will effect the processing and the final properties in it's optimum way only if it is added in the proper amount and sequence.

The most important job in f-PVC compounding (dry blending) is to achieve plasticizer (also know as oil) dry up. Getting a good distribution of stabilizer is also very critical. That's why I add the stabilizers early in the batch process.

Len

[henry_121979]

tnx!tnx!tnx very much len!!! ur so kind and understandable for person like me,im very fortunate that sopmeone like you guys are there to guide me always,now i can move on to my sample trial batch first,im going to do a sample batch in pilot or small batch first,maybe 10% of our big batch size...one concern,my CaCo3 level is at 28 to 30 phr of resin,is it too much for shoe sole formulation?

[Len]

tnx!tnx!tnx very much len!!! ur so kind and understandable for person like me,im very fortunate that sopmeone like you guys are there to guide me always,now i can move on to my sample trial batch first,im going to do a sample batch in pilot or small batch first,maybe 10% of our big batch size...one concern,my CaCo3 level is at 28 to 30 phr of resin,is it too much for shoe sole formulation?

Not at all. Levels of 50 to 75 phr are routinely used in similar f-PVC formulations. W/ that much oil/plasticizer, in my opinion your not going to notice 25 - 30 phr of carbonate.

Please keep us apprised of your progress. And good luck.
Len