A new generation of glues: hybrid CA/ epoxy.
This is an article about an incredible material that we are starting to distribute.
It represents a huge chemical engineering breakthrough: the chemists of Henkel have managed to create a glue that is a mix of CA and structural epoxy.
The name of the product is Loctite 4090.
This is an impressive product for the following reason: it provides the advantages of both CA glue and epoxy:
It sets to a medium hard compound within about 3 minutes and provides decent fixture in that frame of time..
It can be accelerated with CA kicker for instant fixture and sets to 50% strength in 24 hours.
Once fully cured ( one week ) it almost has the strength of Hysol epoxies and displays very good shock resistance properties.
It sustains 300F temperature continuously and does provide excellent aging properties in these conditions.
It resists to most chemicals, including hydrocarbons and gains in strength when exposed to these chemicals up to 1000 hours.
It is shock resistant very much like Hysol 9462.
The glue comes in a 50 ml cartridge that can be put in the usual Hysol glue dispenser gun with 1:1 plungers.
Part A contains CA glue for 70% and the epoxy accelerator for 30%.
Part B contains mostly epoxy resin and a small quantity of CA accelerator.
The two parts are very reactive which each other. On that matter it is very important that they do not come in contact with each other at the cartridge tip.
For this reason the cartridge tip is very different from other Hysol products. The tip has two tubes quite largely spaced from each other that come into each cartridge compartment. The dispensing tip slots into the cartridge throat and can only be inserted one way.
For this reason the Loctite 4090 tips cannot be swapped with other Hysol tips. They are also much thinner and provide very precise dispensing in a thin glue string.
It is not recommended to try mixing the glue without dispensing tips because there is a very high risk of tubes cross-contamination that would render the whole cartridge unusable within minutes.
CA accelerator can be used on a part after assembly to boost the fixture time. Once set, the part has to be left alone for 24 hours before manipulating, and one week if full strength is required.
Storage is recommended in the fridge between 35 and 46 F
The properties of the glue are a fairly good bond to most material with a drop of shear strength compared to Hysol glues of about 15 to 20% except on hard wood.
Shear lap strength on steel is 2420 PSI vs 3000 PSI for Hysol products on average.
Shear lap strength on epoxy is 1320 PSI vs 3300 PSI for Hysol products on average.
Shear lap strength on hard wood is 700 PSI vs 1700 PSI for Hysol products on average.
I found this glue very interesting to assemble scale components like gluing fairings, scoops on the surface of a fuselage. It is also very handy for gear door hinges gluing. For bulkheads gluing in the fuselage, I would still recommend Hysol 9462. However a few dots of 4090 can be placed along the bulkhead to tack glue it in position together with CA accelerator.
This glue is also winner when you need to assemble plywood structures like component trays or gear mount assemblies. For servo brackets, I would still recommend the use of E-20NS or 9462.
Note that full curing property is achieved after one week and 50% after 24 hours. This is clearly not a glue one wants to bring to the field for structural repairs.
