Resorcinol or B-20-S is added at step 2.
Generally，resorcinol can’t be added in step1 due to its significant fuming under temperature as high as to 160-180℃.
It’ known to all that B-20-S is non-fuming, does it can be added in step1?
Usually, B-20-S is used in some skim compounds. One of our customers told us that when mixed with B-20-S, the skim compound got blooming. We can’t see the real conditions of blooming rubber, so it’s not confirmed whether the blooming is caused by addition of B-20-S. What’s your comment?
From some papers drawn by compounders, in the subsequent processing of skim compound, especially when calendering, compound mixed with resorcinol still has problem of fuming. We are confident that B-20-S can resolve this upsetting. What’s your recommendations in the subsequent process?
Additionally, we don’t know how long B-20-S could be stored in normal conditions?
- Penacolite®Resin B-20-S can be added to the first mix stage without significant fuming. However we have seen slightly higher cured modulus if it is added in a later mix stage. Adhesion is not affected by which mix stage B-20-S is added. A B-20-S containing compound should not fume during calendering, however it might be slightly higher in Mooney viscosity than a resorcinol compound so other compound adjustments might be necessary if they cannot tolerate increased Mooney viscosity.
- Penacolite Resin B-20-S does not usually bloom. Several things could be happening:
- Because B-20-S does increase Mooney viscosity, they might be running a higher temperature during mixing or calendering, which may lead to sulfur bloom.
- HMTA (hexamethylenetetramine) is very prone to blooming. If their formulation contains HMTA, this might be causing the problem. When changing from resorcinol to B-20-S it is necessary to lower the level of HMTA. If there is too much HMTA in the formulation, the excess will bloom. When using B-20-S we usually recommend a resin/HMTA ratio between 80/20 and 85/15 (i.e. 3 parts of B-20-S with 0.5-0.75 parts HMTA). We have the ability to analytically determine the composition of the bloom if you want to send a sample.
- We do not have a definite age limit on B-20-S. Chemically, B-20-S does not change with time. The only issue is that over time it might pick up some moisture, which may cause it to agglomerate, making it difficult to handle in the factory. If the resin is in the original un-opened bag this will be a slow process.
From some applications, in resorcinol-HMMM system, the ratio of resorcinol/HMMM can vary from 3/5 to 5/3, even from 1/3 to 3/1. As for methylene donor and acceptor, someone said, one of them is supposed to be excessive in compound. Actually there is no specific ratio for methylene donor and acceptor. But for modified resorcinol, such as resorcinol-80 and B-20-S, is it so?
In resorcinol-HMMM-cobalt system, regardless of active content of HMMM, B-20-S can be used less than HMMM, instead of typical formulation indicated in your presentation. What’s your comments?
As you said, I agree that people use a wide range of resorcinol/HMMM ratios. In our experience a 50/50 resorcinol/HMMM ratio seems to work best (i.e. 3 parts of resorcinol with 3 parts HMMM). The point I am trying to make is that with B-20-S, one does not need to use as much HMMM as when resorcinol is used. For example, if a customer is currently using 3 parts of resorcinol with 3 parts of HMMM, we would typically recommend 3.6 parts B-20-S with 2.4 parts HMMM. That should match the adhesion and tensile properties of the resorcinol compound (but may be slower curing). Using more HMMM than our typical recommendation may increase adhesion and modulus slightly but will significantly increase Rheometer t’90 cure times. Using less HMMM than we recommend can have a negative effect on adhesion. It is a waste of money for someone to use 5 parts of resorcinol with only 3 parts of HMMM, since the resorcinol will not be fully crosslinked. I would encourage that customer to consider using 3.6 parts of B-20-S with 2.4 parts of HMMM instead. They will likely see much greater adhesion with the B-20-S formulation.
For a customer using 3 parts resorcinol with 5 parts HMMM, it might be necessary for them to use a higher level of HMMM to match the properties of their control compound. In this example, I would recommend 3.6 parts B-20-S with 3.6 parts HMMM as a starting point.
From a practical point of view it is important for the methylene donor (HMMM) to be in excess. One mole of HMMM can theoretically react with 6 moles of resorcinol. Theoretically, if one used 3 parts of resorcinol, it is only necessary to use 1.76 parts of HMMM. However our experience shows us that we obtain better adhesion and higher modulus if 3 parts of resorcinol are used with 3 parts of HMMM – a 171% excess of HMMM! Since B-20-S is already partially crosslinked, it is not necessary to use as much HMMM as is used with resorcinol, however there should still be an excess of HMMM.
We have not evaluated Schenectady’s A250. We have been unable to obtain a sample of it. If you can obtain a sample for us, we would appreciate it.
We have looked at the other resin in the report, PN759. Attached is our report on this material. The big negatives for PN759 and likely the Schenectady resin (or any phenolic resin) are greater heat buildup (hysteresis, tangent delta) than B-20-S and poorer aged adhesion. Your customer’s data show’s a 9% increase in heat build-up with the Schenectady resin and a 24% increase with PN759. Our testing confirms the PN759 results. One of the unique features of the PN759 resin is that the tangent delta INCREASES with increasing temperature. This is very unusual and very bad for tire performance. With both B-20-S and resorcinol, the tangent delta decreases with increasing temperature. As a tire fails, it builds up heat. With PN759 (or possibly Schenectady’s A250) in the compound, the rubber becomes MORE hysteretic, causing the rubber temperature to build at a faster rate than if the compound had contained resorcinol or B-20-S, which actually becomes LESS hysteretic with increasing temperature. There is the potential that a tire containing PN759 (or possibly Schenectady’s A250) could fail faster than if it had contained resorcinol or B-20-S.
The aging conditions in your customer’s report are relatively mild. Even with their relatively mild aging conditions, the Schenectady resin is worse for salt water aging. I would encourage your customer to run longer aging tests. A good aging test, which doesn’t require any special equipment is to age the sample 2-3 weeks in water at 85C. When we water age, we place the samples in a glass tray, cover the tray with aluminum foil to prevent most evaporation, and place the tray in an 85C oven. Even with the cover, it is necessary to adjust the water level every several days. A longer term test like this, should show a clear advantage to using B-20-S. It is very difficult to tell one resin from another when one only ages 48 hours at 100C.
The only significant difference between B-21-S and B-20-S is that B-21-S is faster curing than B-20-S. The other differences you mention are just experimental error. Chemically, B-21-S has a higher free resorcinol content and a lower amount of styrene than B-20-S. The CRL-410 resin is slower curing than B-20-S and has a lower free resorcinol content and a higher amount of styrene than B-20-S. (Therefore, one could conclude that the amount of styrene in the resin effects the cure rate and the amount of free resorcinol.)
Question：One of our customer said they made a virtual dynamic test of all-steel tire incorporated with B-20-S, the result seemed not good. Main issue focused on the heat generation. They guess it may be related to its relatively high styrene content. We’ll let you know the details of that report when that customer finish.
We think its hydrophobic property may be relevant to the high styrene content, but, for B-20-S, how does the styrene influence on other properties of rubber? Could it act as a plasticizer compared with B-19-S or B-21-S? For these free styrene, they contain double-bonds in their molecular structure, do they consume some sulfur in vulcanization?
Sometimes we are told the rubber stocks incorporated with B-20-S is difficult to process in mixing or in calenderring, is it because of the slight pre-crosslinking of resorcinol and formaldehyde?
We know B-21-S is slightly styrenated, someone said it’s the only difference between B21 and B19, really?
Answer：Yes, I received your samples of A250 and A150. We have the A250 on test, but have not started testing the A150. We should have results on A250 in a couple of weeks. We heard that Schenectady is no longer promoting the A150. Have you heard the same?
For the customer that made a test with an all steel tire and saw a problem with heat generation, what material was B-20-S compared to? How much HMMM did they use? We have not seen any problems with heat generation and B-20-S.
The styrene in B-20-S is reacted onto the benzene ring of the resorcinol. The styrene reacts at the double bond, so the unsaturation of styrene is gone in B-20-S. The styrene in B-20-S does not react with sulfur. There is no free styrene in B-20-S, it is all reacted.
Styrene does help to make B-20-S hydrophobic. I would not call the styrene in B-20-S a plasticizer, however, we see slightly lower Mooney Viscosity with B-20-S than with B-19-S.
Typically, a B-20-S compound is more difficult to process than a resorcinol or a Rhenogran 80 compound. The B-20-S compound is more difficult to process because B-20-S has a higher molecular weight than resorcinol and causes a higher Mooney Viscosity. Resorcinol is a monomer. B-20-S is an oligomer, some of the resorcinol has been pre-reacted with formaldehyde. The molecular weight of resorcinol is 110.11. The number average molecular weight of B-20-S is about 450 –four times bigger!!
B-21-S contains 4 basic ingredients, resorcinol, formaldehyde, styrene and resorcinol polymer. B-19-S contains 3 basic ingredients, resorcinol, formaldehyde and resorcinol polymer. The ratios of these ingredients are different in B-19-S and B-21-S. We did not just add styrene to B-19-S to make B-21-S.