Cost effective Epoxy formulation

Would like to know what a good, cost effective formulation would be using Epon 828 for wooden boat building.

Part one, Epon 828 is the basic resin (bisphenol A) found in almost all two part epoxies. There are just basically 3 manufactures of resin in North America. It can be had for $25.00 a gallon if bought in 55gal drums.

Something called a modifier/epoxied is also used, it is really another form of the resin and its mixed in very small proportions to the basic resin.

Part two, the hardener comes in hundreds of varieties, mixing ratios, and many manufacturers. Two well known hardeners that also work well are DETA and TETA. They are cheap ($30.00 a gallon) but are very toxic, so other alternatives have to be used. Other popular hardeners that are less toxic are cycloaliphatics, aliphatics, and polyamides.

As you can see the whole system can be purchased by anybody for less the $30.00 per gallon in bulk. Epon 828 is very thick and its viscosity (14,000 centipoise) has to be reduced to make it workable (1000 centipoise and under is ideal).

Many formulations are well known by end users, some are trade secrets (WEST,MAS, etc.) but epoxy has been around now for over 60 years and it characteristics are well know by even casual chemists and can be easily formulated to your desired qualities.

Question: What are some favorite epoxy formulations used by boat builders?

 

And they will rush to share that with you
You will have, I am afraid, to make your own home work, invest the $50 plus the $30 and try.
Then I will ask you your formulation
Just kidding.
I think the only one who can answer your question will be Richard.
Daniel

 

Calling Richard.....

Seriously, most of us pay a little more and just buy it. It takes years of experience and experiment before you get a good mix, much less a better combination. I have done it, and determine it was better to buy to get consistency, advantage in price was lost by having remove bad epoxy that never adhere or held properly. Epoxies are art and science in one...

 

In the region where I work, I am not aware of any boatbuilder formulating his own epoxy, as in modifying a base resin.

Some of my clients modify resins, for various reasons, most are basicly Epon 828 or similar, with 1,2 hexane diol.
Get yourself a catalogue of what is available in your region, in terms of base resins and reactive diluents, and ask for a couple of samples. I would first tackle the resin, and concentrate on curing agents later. These are far more complicated. I even doubt that you will be able to source all ingredients from a resin supplier. Also most formulators are a bit wary for sharing their trade secrets. Check the MSDS and you will get a general idea. Many curing agents are IPD based, at least in my field.

As for sourcing cheap resin, I would definately check usable/workable systems from your suppliers, make a request for the complete year, and have them base an offer on that, instead of small batches. The prices you mention could be reduced somewhat, although resin prices are rising at the moment. (especially Hexion / Shell)
Mixing your own is fun, but the hours spent cannot be invoiced on any project. They are overhead. However, they can give you understanding of the product.

 

Let me just second Hermans comments!

The statement that epoxies "are well know by even casual chemists and can be easily formulated to your desired qualities"
is not true.
It is a field most boatbuilders don´t play on! We ask our suppliers to formulate to our demands. (it is his insurance paying the screwed hull, not mine)

Regards
Richard

 

Good post Herman,

As stated, epoxy manufacturers have system formulas that can be aquired for free in small batches to get familiar with their products. Went to your website but could not correspond the Hexion curing agent numbers with what is available through thier website in North America.

Also correct, that you can get MSDS sheets on epoxy formulators products and have probably 90% of thier formula. That is also one reason for trying to find a different curing agent because most of them use amines to a high percentage and those are the dangerous ones.

Apex, can understand that you feel more comfortable using well known brands and furthermore you can use that to sell your product, but its still correct that a good formulation can be had going the bulk route.

One example that was learned on this forum was from jimbo. He also has worked in the composites field and is very knowledgable in it.

His suggestion was to use Hexion 862 which is a bispenol F, which has better characteristics than almost any resin used in name brand formulas, used with a cVc cycloaliphatic hardener gets down to 1000cps if further thinning needed reactive modifier 62 can be added in small amounts.

Two requirements that are absolutely needed, they are:
1. Low viscosity.
2. Working time.
With these two met most other things like flexibility, abrasion, bonding, and tensile can be adjusted because epoxy has such superior strength. If for instance you went with something with a high abrasion you might get low flexibility, but the flexibility would still be very strong to build with, unless you go into something very unusual and weak, those would be spotted quickly by just comparing those characteristics with other CA on the flexibility number.

With a little research this route can have tremendous savings of paying $30.00 a gallon vs. $90.00 gallon with good possibility of better quality epoxy.

 

As former experimenter with epoxy to try to save a little money...The problem comes several months later when it starts to peal off. Not all epoxies are the same not all are 100% water proof, not all bond to everything. Also you may need to add additives like for UV.

 

mydauphin, you are right with being careful in your formulation, this is the reason for asking other boatsmiths of thier formulas if they mix their own.
UV protection is needed only if the boat is not going to be painted, otherwise
painting is sufficient UV protection.

 

I guess you misunderstood something. I do not use known brands (I am not a idiot) I get my stuff formulated as I want it. And I process some 800 or so tonnes per year. They are all very keen to provide exactly what I want, and of course the prices are a bit lower than for the homebuilder.

The latter should not try to experiment with formulations, he could probably screw up his entire project, and notice that only after launching!

Btw.
I still have to meet the customer who asks for the resin we process.................

Regards
Richard

 

Goodwilltoall you are sitting in the best location in North America for epoxy formulation. If you want good ideas there are a few books that you can read at the College of Polymer Science and Polymer Engineering library at U of Akron with Epoxy formulations for marine use. They are not available for check out so get in yur car.

You can buy it already formulated for not much more than $30 per gallon if you know where to go.

 

I might be interested in that book as well. What does it cost? Do you happen to know? And if someone is picking up that book, would he be so kind to pick one up for me as well?

 

http://www.amazon.com/Epoxy-Adhesive-Formulations-Chemical-Engineering/dp/0071455442
Maybe this..

and some commercial links to formulators etc..http://www.globalspec.com/industrial-directory/epoxy_formulations_inc

 

Sorry about the names of those books. It was a good ten years ago when I was scanning those books for a project. I doubt I would even recognize the books on Amazon.com.

I was easy for me because I am located very near Akron and formulate adhesives.

 

Pierre,
Akron U is a top polymer researcher with the major tire manufacters located there. Might have to eventually do more research overthere, but hope not.
With information widely available through the internet its much easier to just click.
Thought there might be formulations brought out that could be considered and wieghed for price and qualities.

Apex, other than actually mixing formulas, how did you originally learn the characteristics of certain mixes?

 

How does one learn about material properties?
As a boatbuilder you specify what you want for your money, and kick the suppliers asses when they don´t deliver what you paid for.
And be sure, when you come above the 20 - 30 tonnes figure annually, they do what you want, and they do it right.

But that does not help you (or any homebuilder). And it must not in this case, because you still don´t even know which sort of craft to build, but screw with Epoxy formulations even Herman, Jimbo and our "Mexican" specialist would fear.

Regards
Richard