What does vulcanizing solution in patch kits consist of? Can I buy it?

Question

I have a pile of old patch kits for inner tubes that are complete except for the little tube of "vulcanizing solution" that comes in patch kits. With time, these tubes crack, or have a cap fail to seal perfectly, and dry out completely. I would love to be able to buy a larger container of solution.

Vulcanizing solution appears and smells like rubber cement but I've seen suggestions that rubber cement simply contain similar solvents and/or polymers. None of my patch kits describe the chemicals in the vulcanizing solution tubes.

What is vuncalizing solution made of?

Can I obtain it in quantitites larger than a tiny tube in a patch kit? Could I make it? Can I at least obtain larger quantities of the little tubes?

Answer 1

The manufacturer sells said "vulcanizing solution" in quantities of 25g tubes through 1 gallon cans, so you should be able to buy it in larger quantities. Indeed, a quick search of Amazon yield 8 oz cans (or slightly cheaper), and while I couldn't find it on something well known like Amazon there are other places that sell the 1 gallon quantity. However, as many of the reviewers on Amazon point out, an 8 oz can should be a lifetime supply, and won't dry up nearly as quickly as those little tubes.

As far as what it is, that's a little harder to figure out. Checking the MSDS, we find only that it consists of 40-70% trichloroethelyne, an organic solvent. That doesn't really solve the problem, as that's just the solvent used.

To address the question of rubber cement, if we follow your link to Wikipedia, we find that it's generally a non-vulcanizing cement, while the tire patch stuff definitely claims to be vulcanizing.

Moving on, we can think about what the traditional solution to closely held trade secret formulas is. And the tool that was designed to solve that, though only does so imperfectly, is the patent system. Maybe we can find something in a patent filing.

A quick check over on Google Patents yields something promising, Cold self-vulcanizing rubber compositions; however, upon reading the patent, it's a three part mixture, and the process involves things like "the rubber used is a natural rubber, partially depolymerized by mechanical working and peptization with diorthobenzamidophenyl." I don't know about you, but peptization with diorthobenzamidophenyl is not exactly something I feel like trying to cook up with common household substances in my basement.

Reading further on, we find some further promising patents like Tire repair with cured patch or Tire repair by "patch only" method, but they all also involve discussions of the following form:

Suitable vulcanization accelerators include, but are not limited to, thiazoles, sulphenamides, guanidines, thiourea derivatives, amine derivatives, and combinations thereof. Examples of these include, but are not limited to: N-cyclohexyl-2-benzothiazyl sulfenamide (CBS), dibenzylamine (DBA), N-N'-diphenylguanidine (DPG), Dicyclohexylamine (DCHA), 2-mercaptobenzothiozyl disulfide (MBTS).

As well as references to entire books on rubber and the process of vulcanization: 'Rubber Technology, edited by Maurice Morton, Chapter 2, "The Compounding and Vulcanization of Rubber," 3rd edition, 1987'

None of these appears to have any kind of description of a single readily available material or combination of a few that could be mixed together to work; they all appear to be fairly intricate, specialized compounds consisting of a variety of ingredients.

So I think that the 8oz can on Amazon is probably your best bet. I've heard some people claim you can just use regular rubber cement, but given that there are big cans of the "vulcanizing solution" readily available, my instinct would be to go for that.

Answer 2

For those that are curious what the difference is between "rubber cement" and "vulcanizing fluid", here's a summary of the chemistry.

The actual process of vulcanization of rubber (Thank you Charles Goodyear) involves the introduction of cross-links between the strands of rubber through a high temperature process. The cross-links are composed of sulfur atoms, and they act to strengthen the rubber.

Vulcanizing solution does not actually vulcanize rubber. What it does is to break the bonds between sulfur atoms in these crosslinks of rubber that has already been vulcanized (for chemists out there, it's a reduction of disulfide bonds). In the presence of oxygen, the bonds between the sulfur atoms slowly reform and restore the crosslinks. If new rubber, such as a patch, is in contact with the old rubber and has exposed sulfur atoms, new cross-links can be formed between the old and new rubber. The result is a true (covalent) chemical bond between the inner tube and the patch. This is called "cold vulcanization", but shouldn't be confused with true vulcanization.

In contrast, rubber cement is simply rubber polymers in a solvent. When you use rubber cement, the surface polymer molecules of the rubber get tangled up with the rubber molecules in the cement as the solvent dries, but there is no new chemical linkage (by which I mean a covalent bond, chemically speaking) between the molecules.

For most applications, both methods generally work fine for patching an inner tube, but the cold vulcanization creates a stronger bond.

Answer 3

The problem with a larger container would be if it didn’t seal properly and evaporated like your small tubes have before, you’d have the same problem. What you need is a stock of smaller tubes you can keep sealed.

Try searching online for a supply of small tubes (I can find 10 small tubes for $4 on eBay where I live). Then open a fresh tube each time you need some, if the previous tube has evaporated.

Answer 4

According to the safety sheet of the vulcanizing solution type D intended for tyre repair made by Ferdus it is "solution of a rubber compound in liquid hydrocarbons predominantly of a paraffinic character", i.e. C6-C7, n-alkanes, isoalkanes, cyclic, <5% n-hexane) 92%, in which there is: cyclohexane 10%, n-hexane < 5%. An old version of the safety sheet for type D solution also listed <1% of toluene and <0.1% of benzene.

The manufacturer's e-shops shows packagings from 4 ml to 800 ml (no idea whether that is more or less than a gallon).

Another vulcanizing solution type F consists of a similar mixture of rubber in paraphinic hydrocarbons, but different ones: (C6-C7, n-alkanes, isoalkanes, cyclic, < 5 % n-hexane) 84% in which: cyclohexane 10%. The intended usage listed is the same as for the former, but the smallest packaging is 100 ml, it does not come in the small one for bicycle repair sets.

They also have another type T which is intended for refreshing the surfaces of tyres and inner tubes and has similar ingredients as type F, at least when considering the dangerous chemicals listed in the safety sheet.

Answer 5

Is it possible to refresh the evaporated tube with brake parts cleaner? I guess, it is, because only the solvent evaporates the functional ingredients are still there. I figured out that old rubber cement is very good removable from the inner tube with brake parts cleaner, if you want to redo your work. I will test that.

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UPDATE: Dried up fluid: mix it with brake cleaner, let it sit a few months, after that it is as good as new. Tested.

Answer 6

It's not the cap that causes the unused tubes of patch glue to dry. It's the crimp on the other end. The crimp isn't perfect, and the solvent in the patch glue is highly evaporative.

I suspect the manufacturers of these tubes fill the tube with glue, but not completely, and have the cap end down and crimp end up on the assembly line. Thus, there is a pocket of air near the crimp. Then the tube is crimped shut, but air remains there. If you store the tube in an orientation where the crimp is up and cap is down, the pocket of air remains near the imperfect crimp. Due to temperature changes, the pressure inside the tube changes, and the pressure differential allows the evaporated solvent to escape through the imperfect crimp.

You can reduce the occurrence of this by following several instructions:

1. Store all tubes crimp end down, cap end up. It's bit harder that way, since the tube doesn't naturally stand crimp end down. This ensures that the evaporated solvent can't escape through the crimp, but rather what should escape is the liquid, and liquid is always more viscous than gas.
2. Every time you use the glue in a tube, before closing the cap, turn it in such a manner that the cap end is up. Then push all air away from the tube, so that the liquid glue is pouring away near the cap threads. Only then close the cap, so that no air remains inside the tube.

Actually, it might also be beneficial to manually open every glue tube in a patch kit, and to procedure (2) to ensure that no air is inside the glue tube.

Also it is beneficial to use name brand patch kits (Rema Tip Top), and only buy them from stores that have a high turnover rate so that you know you get a newly manufactured tube and not something that could be years old.