How to apply alicyclic epoxy resin in UV light curing coating?

January 6, 2023 Longchang Chemical

How to apply alicyclic epoxy resin in UV light curing coating?

UV curing technology is broadly divided into UV free radical and UV cationic systems, UV cationic coatings with excellent processing properties in metal cans, rolled steel and flexible packaging industry is widely used, the main market is now also In Europe and the United States.

 

 

UV cationic and UV free radical materials are very different, but the overall composition is similar. Cationic systems are dominated by epoxy materials, but ordinary bisphenol A type epoxy reacts slowly, with more applications of alicyclic epoxy/oxetane type materials; free radical systems are now very mature commercially, with epoxy/polyester/polyurethane modified acrylate materials providing more choice of solutions.

 

UV cationic system can choose fewer kinds of raw materials compared to free radical system, and the polymer is mainly low viscosity alicyclic epoxy resin. Take alicyclic epoxy resins as an example.

TTA21 of various purity specifications is the most dominant product in the UV coating industry. As the application of cationic UV coatings continues to grow significantly, it is expected that the amount of alicyclic epoxy resins represented by TTA21 will increase.

 

In the specific product application of ink/coatings, in addition to both needing UV light to provide curing energy, the two systems show major differences in performance and reaction characteristics.

 

1. Oxygen-blocking effect

UV cationic system does not have the effect of oxygen-blocking, but is more afraid of water, moisture will affect the curing efficiency of the cationic system; UV free radicals are the opposite, and are more affected by oxygen-blocking.

 

2. Substrate adhesion

Usually in the more difficult to adhere to the surface of the substrate, such as glass / metal / high-density plastic, UV cation than UV free base has better adhesion performance.

 

3. Volume shrinkage rate

UV free radical system formulation curing shrinkage rate is generally above 10%, while UV cation system can control the shrinkage rate of 1-3%, is a good solution to solve the volume shrinkage.

 

4. Dark curing characteristics

UV cation system can continue to react to the inner layer after stopping the light source irradiation, to complete the material after curing, this is the dark curing characteristics, very suitable for thick coating applications, heating the cation after curing speed is significantly helpful; UV free radical is a stop-and-go reaction system.

 

5. Contact safety

UV cation system reaction degree is close to 100%, safety can be REACH / FDA testing certification, can be used in food packaging and other related fields.

 

6. Light curing speed

In general the UV free radical system curing speed than the cationic system, affected by oxygen-blocking products cationic surface drying will be faster, but the actual drying speed is not as fast as the free radical, you can promote the reaction by heating, and eventually can reach a very good degree of completion.

 

Formulation notes

 

UV cation system can be mixed with UV free radical system in any proportion, called UV hybrid system, can improve the relative curing speed of UV cation and UV free radical shrinkage, affected by oxygen barrier and other shortcomings, the same film thickness of the system curing energy difference is not large.

 

UV cation system is to rely on the initiator generated by Lewis strong acid to do the active point of the ring-opening reaction, the formula will commonly affect the initiator activity of the material is mainly azo organic pigments (can be modified to do protection), and free radicals mixed with TPO/819/907 and other structures containing P, S and other elements of the initiator, and similar to 115 multi-level amine.

 

Humidity has a greater impact on the UV cation system curing, control the ambient humidity within 50% is appropriate; while heating will speed up the reaction rate.

 

UV Photoinitiator Same series products

 

Photoinitiator TPO CAS 75980-60-8
Photoinitiator TMO CAS 270586-78-2
Photoinitiator PD-01 CAS 579-07-7
Photoinitiator PBZ CAS 2128-93-0
Photoinitiator OXE-02 CAS 478556-66-0
Photoinitiator OMBB CAS 606-28-0
Photoinitiator MPBZ (6012) CAS 86428-83-3
Photoinitiator MBP CAS 134-84-9
Photoinitiator MBF CAS 15206-55-0
Photoinitiator LAP CAS 85073-19-4
Photoinitiator ITX CAS 5495-84-1
Photoinitiator EMK CAS 90-93-7
Photoinitiator EHA CAS 21245-02-3
Photoinitiator EDB CAS 10287-53-3
Photoinitiator DETX CAS 82799-44-8
Photoinitiator CQ / Camphorquinone CAS 10373-78-1
Photoinitiator CBP CAS 134-85-0
Photoinitiator BP / Benzophenone CAS 119-61-9
Photoinitiator BMS CAS 83846-85-9
Photoinitiator 938 CAS 61358-25-6
Photoinitiator 937 CAS 71786-70-4
Photoinitiator 819 DW CAS 162881-26-7
Photoinitiator 819 CAS 162881-26-7
Photoinitiator 784 CAS 125051-32-3
Photoinitiator 754 CAS 211510-16-6 442536-99-4
Photoinitiator 6993 CAS 71449-78-0
Photoinitiator 6976 CAS 71449-78-0 89452-37-9 108-32-7
Photoinitiator 379 CAS 119344-86-4
Photoinitiator 369 CAS 119313-12-1
Photoinitiator 160 CAS 71868-15-0
Photoinitiator 1206
Photoinitiator 1173 CAS 7473-98-5

 

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