What are the component raw materials of light-curing UV coatings?
Quick answer: For practical formulation work, photoinitiator screening starts with the light source and film build, then checks yellowing, adhesion, and cure completeness under real production conditions.
Ultraviolet curing (UV) coating is a new type of environmentally friendly coating. It has an extremely fast drying rate and can be cured in just a few seconds by UV light, with a high production efficiency.
UV cured coatings are mainly composed of oligomers, reactive diluents, photoinitiators and additives.
1. UV Oligomer
The film-forming compound is the main composition of the coating, which is the fluid component in the coating. The coating film performance, construction performance and other special properties of the coating mainly depend on the film-forming compound. UV coating film-forming compound is oligomer, its performance basically determines the construction performance and light curing rate of the coating before curing, the coating film performance and other special properties after curing.
UV coatings are mainly free radical light curing systems, so the oligomers used are various types of acrylic resins. Cationic UV coating oligomers are epoxy resins and vinyl ether compounds.
2.Active diluents
Active diluents are another important component of UV coatings, which can dilute and reduce viscosity, and also have the ability to adjust the performance of the cured film. The acrylate functional monomer has high reactivity and low volatility, so it is commonly used in UV coatings. acrylates are commonly used as active diluents for UV coatings, and in the actual formulation, single, double and multi-functional acrylates will be used together to make their performance complementary and achieve good overall effect.
3. Photoinitiator
Photoinitiator is a special catalyst in UV coatings, it is an important component of UV coatings, to determine the light curing rate of UV coatings.
For colorless varnish UV coatings, photoinitiators are often used 1173, 184, 651 and BP/tertiary amine. 184 high activity, low odor, yellowing resistance, is the preferred photoinitiator for yellowing resistant UV coatings, in order to improve the light curing rate, often used in conjunction with Photoinitiator TPO.
For colored UV coatings, photoinitiators such as ITX, 907, 369, Photoinitiator TPO, and Photoinitiator 819 are commonly used. Sometimes UV coatings in order to reduce oxygen blocking, improve the light curing rate, often into a small amount of active amine.
4. Additives
Auxiliary agent is the auxiliary component of UV coating. The role of additives is to improve the processing performance of coatings, storage performance and construction performance, improve the film performance and give the film some special features, etc. UV coatings commonly used additives are defoamer, leveling agent, wetting and dispersing agent, adhesion promoter, matting agent, resist, etc., they play a different role in UV coatings.
Is the smell of UV printer toxic?
UV printer is a kind of printing equipment that responds to the green environment. Due to the uniqueness of the UV printer curing method, in the UV light curing process, it is inevitable that some odor will be generated. Many friends who have purchased or plan to purchase UV printers, there are such questions about the smell: whether the smell is toxic, how to deal with it?
Of course, the user’s concern about the smell is normal, especially those who are not too clear about the UV printer printing process, the smell will be more obvious when using a flatbed UV printer to print large-format materials. To answer the above questions, we should first understand the composition of the UV printer ink. After all, the source of the odor lies in the UV ink.
UV ink is mainly composed of photoinitiators, reactive diluents, oligomers and various additives. UV printer ink layer is formed by: photoinitiators absorb UV light to produce free radicals or cations, causing reactive diluents and oligomers polymerization cross-linking reaction. Odor mainly from the UV ink acrylates, but also a small amount from the additives. Odor will slowly fade in a short period of time eventually disappear, and really harmful to humans and must pay attention to heavy metals such as lead, cadmium, mercury, hexavalent chromium, as well as polybrominated biphenyls, polybrominated diphenyl ethers, phthalates and other volatile high, odor, allergy-prone substances content exceeds the standard. At present, the regular manufacturers of ink can provide the above substances test reports.
Since we know the composition of UV ink, the source of odor and the focus to detect which harmful components, we only need to do the following in the actual product selection, printing production, you can not worry about poisoning or other serious harm to the human body occurred. First of all, we must choose a guaranteed brand of UV printer manufacturers, choose their compatible ink, it is best to let them issue test reports; secondly, regardless of whether the smell is toxic, for insurance and operator comfort considerations, the use of the production environment to have good ventilation, the conditions of the unit can be configured with some gloves, masks and other protective equipment; finally, the printing of waste to facilitate recycling or disposal To avoid “secondary pollution”.
A practical selection route for photoinitiator-related projects
When technical buyers or formulators screen photoinitiators, the most useful decision frame is usually cure quality plus application fit: which package cures reliably, keeps appearance acceptable, and still works under the lamp, film thickness, and substrate conditions of the actual process.
- Match the package to the lamp first: mercury lamps, UV LEDs, and visible-light systems can rank the same photoinitiators very differently.
- Check depth cure and surface cure separately: a film that feels dry on top can still be weak underneath.
- Balance yellowing with reactivity: the strongest deep-cure route is not always the best commercial choice if color or migration risk becomes unacceptable.
- Use the final formula as the benchmark: pigment load, monomer package, and film thickness can all change the apparent ranking of the same initiator.
Recommended product references
- CHLUMINIT 819: Useful when a formulation needs stronger absorption and deeper cure support.
- CHLUMINIT 184: A classic free-radical benchmark for fast surface cure in many UV systems.
- CHLUMINIT 1173: A practical comparison point for classic short-wave UV initiation.
- CHLUMINIT ITX: A useful long-wave support route in many printing-ink packages.
FAQ for buyers and formulators
Why are blended photoinitiator packages so common?
Because one product may control yellowing or lamp fit well while another improves cure depth or line-speed performance, so the full package is often stronger than any single grade.
Should incomplete cure always be solved by adding more initiator?
Not automatically. The real limitation may be the lamp, film thickness, pigment shading, or the rest of the reactive system rather than simple under-dosage.