Acryloylmorpholine in UV-Curable Coatings and Adhesives

Acryloylmorpholine (ACMO, CAS 5117-12-4) is a low-viscosity, water-soluble acrylate monomer used mainly as a reactive diluent in UV- and electron-beam-curable coatings, inks and adhesives. This page explains what it does in the formulation.

What a reactive diluent does

UV inks and coatings must be applied at a workable viscosity, but they cannot simply contain solvent (which must evaporate, causing emissions and shrinkage). A reactive diluent solves this: it thins the formulation like a solvent, but then reacts into the cured film instead of evaporating.

Function	Reactive diluent (e.g. ACMO)	Solvent
Lowers viscosity	Yes	Yes
Ends up in the film	Yes (reacts in)	No (evaporates)
VOC emissions	Very low	High
Effect on film properties	Part of the crosslinked network	None after drying

Why ACMO specifically

Property	Benefit
Water-soluble	Works in aqueous and solvent systems; improves substrate wetting
Low viscosity (9 – 15 mPa·s)	Efficient thinning at low use levels
Low colour (50 APHA max)	Suits clear and light-coloured coatings/inks
Polar, amide functionality	Good adhesion, including to difficult substrates
Mono-functional	Contributes flexibility rather than over-rigidity

Where ACMO is used

Product	Role of ACMO
UV/EB coatings	Reactive diluent that cures into the film
Graphic-arts inks	Reactive diluent/monomer for UV inks
Overprint varnishes	Low-viscosity, low-colour monomer
Adhesives	Monomer for radiation-curable and specialty adhesives

Formulation notes

Level – added as the reactive diluent, set by the target viscosity and cure speed.
Cure – polymerises with the rest of the system under UV/EB or peroxide initiation.
Hygroscopic – moderately hygroscopic (1.8 g/100 g at 60% RH); keep sealed and account for moisture pickup.
Inhibitor – contains about 1000 ppm inhibitor; do not strip it out.

Frequently Asked Questions

Why use ACMO instead of a solvent?

Because it is a reactive diluent: it lowers viscosity but reacts into the film, so there are almost no volatile emissions and the film keeps the material.

Why ACMO rather than another acrylate?

Its water solubility, low viscosity, low colour and good adhesion make it especially useful in aqueous and adhesion-critical systems.

Is ACMO mono- or multi-functional?

Mono-functional, so it acts as a diluent and contributes flexibility rather than high crosslink density.

What is the use level?

Set by the target viscosity and cure speed; confirmed by formulation testing.

How is it stored?

Sealed, cool and dark; it is a reactive monomer containing an inhibitor.