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Investigating the Chemical Properties of UV 3D Printing

Release time:

2026-07-15 23:10

Investigating the Chemical Properties of UV 3D Printing

The core of UV‑3D printing technology lies in the photopolymerization reaction of photosensitive resins, a process that involves intricate chemical transformations. From the molecular structures of monomers and prepolymers in the liquid resin, to the reactive species generated by the decomposition of photoinitiators under UV irradiation, and finally to the formation of crosslinked networks and the resulting material properties, chemical principles permeate the entire printing process. Unlike FDM, which relies on physical melt‑based deposition, UV‑3D printing is fundamentally a chemical reaction—specifically, a UV‑initiated polymerization‑crosslinking process. A thorough understanding of these chemical characteristics enables one to grasp, at the molecular level, the underlying logic governing material performance, process optimization, and application selection.

I. Chemical Composition of Photopolymer Resins

Photosensitive resins consist of three major components: oligomers, photoinitiators, and reactive diluents. Among these, the oligomer (also known as a pre-polymer) is the key constituent that determines the material’s principal properties after curing. Different types of oligomers impart distinct performance characteristics to the material.

Epoxy acrylates are one of the most widely used types of oligomers. They cure rapidly, yielding cured films with high hardness, excellent gloss, and superior chemical resistance; however, they tend to be relatively brittle and exhibit poor yellowing resistance. Polyurethane acrylates contain urethane linkages that can form multiple hydrogen bonds between polymer chains, resulting in cured films with outstanding abrasion resistance and flexibility, as well as good adhesion to substrates such as plastics, thus delivering overall superior performance. Polyester acrylates have lower viscosity and offer better flexibility and pigment wetting properties.

In free-radical photopolymerization systems, reactive diluents are monomers containing unsaturated double bonds, with photoreactivity increasing in the following order: acryloyloxy, methacryloyloxy, vinyl, and allyl. In contrast, cationic photopolymerization systems employ resins bearing epoxy groups or vinyl ether groups.

II. Photoinitiated Polymerization Reaction

The curing process in UV 3D printing is a typical photoinitiated polymerization reaction. Depending on the photoinitiating mechanism, it is broadly classified into two major categories: radical‑based photopolymerization systems and cationic photopolymerization systems.

In free-radical systems, photoinitiators absorb light energy under UV irradiation and decompose to generate highly reactive radical species. These radicals attack the unsaturated double bonds in monomer or oligomer molecules, initiating a chain‑growth polymerization reaction. This process proceeds rapidly, but the radicals have short lifetimes and are subject to oxygen inhibition. For printed parts requiring high surface cure quality, oxygen inhibition can lead to a tacky surface, compromising print accuracy.

Cationic photocuring systems generate acids via a photoinitiator, which in turn initiates the polymerization reaction. Cationic polymerization proceeds at a slightly slower rate than free-radical polymerization; however, the generated acid can persist for an extended period, endowing cationic systems with dark‑curing capability—meaning that once irradiation ceases, the polymerization reaction can continue. This property enables cationic photocurable resins to achieve curing even in shadowed regions where light cannot penetrate, making them well suited for deep‑layer curing of complex‑shaped components.

III. Formation and Shrinkage of the Crosslinked Network

Photopolymerization causes the monomers in the liquid resin to crosslink among themselves, forming an irregular three-dimensional crosslinked network. This chemical transformation is accompanied by volumetric shrinkage: the intermolecular distances in the liquid resin correspond to the range of van der Waals forces, whereas upon curing these distances are reduced to covalent bond lengths, leading to a decrease in molecular spacing and, consequently, macroscopic volume contraction.

Shrinkage is a critical issue in UV‑3D printing, as it generates internal stresses that can lead to deformation, warping, or cracking of printed parts, thereby compromising print accuracy. The magnitude of shrinkage is closely linked to the chemical structure of the resin system; developing low‑shrinkage resins is one of the key research directions in photocurable materials.

IV. Photosensitivity

Photosensitive resins used in UV‑based 3D printing must exhibit high photosensitivity, a requirement dictated by the characteristics of the printing process. Some technologies employ lasers as the light source; because laser wavelengths are relatively monochromatic, the absorption wavelength of the photoinitiator should closely match the laser wavelength and fall within a narrow range. This ensures that curing occurs exclusively at the laser‑irradiated spot, thereby enhancing fabrication accuracy.

Different wavelengths of ultraviolet light correspond to different photoinitiator systems. The photosensitivity of the resin is also reflected in its curing rate—completing a printed part typically requires curing hundreds to thousands of layers; if the curing rate is insufficient, it not only compromises print quality but also directly impacts production efficiency.

V. The Duality of Chemical Stability

The highly cross‑linked polymer network formed by UV‑based 3D printing imparts superior thermal and chemical stability to the printed parts—key advantages—but also introduces a significant drawback: the cross‑linked network is difficult to degrade and recycle.

By incorporating compounds containing cleavable chemical bonds into the resin system, it is possible to impart degradability to printed parts under specific conditions without significantly compromising their printability or mechanical properties. This chemical modification approach offers a new avenue for enhancing the recyclability and sustainability of photocurable 3D‑printing materials.

VI. Conclusion

The chemical properties of UV‑3D printing encompass multiple aspects, including the structure and functionality of resin components, the types and mechanisms of photoinitiated polymerization reactions, the formation of crosslinked networks and associated shrinkage effects, as well as light sensitivity and chemical stability. The rapid curing characteristic of radical‑based systems meets the demands of high‑efficiency printing, while the dark‑curing nature of cationic systems is well suited for deep‑layer curing in complex structures. A resin’s light sensitivity determines its compatibility with specific light sources, and the chemical stability conferred by the crosslinked network represents both an advantage and a challenge. A thorough understanding of these chemical properties underpins the optimization of printing processes, the selection of appropriate materials, and the development of novel biodegradable photosensitive resins.

Disclaimer: The above content has been compiled from publicly available sources and is provided for reference only. If any infringement occurs, please contact us, and we will address it promptly.

Bossin Related Product Recommendations – 3D Printing
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Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-100	Bisphenol A epoxy acrylate	High hardness, high gloss, excellent chemical resistance, and rich body.
B-113	Bisphenol A epoxy acrylate	High hardness, high gloss, high fullness, containing 20% TPGDA.
B-221	Aliphatic polyurethane acrylate	Fast curing, resistant to boiling water
B-276H	Aliphatic polyurethane acrylate	High hardness, fast curing, excellent toughness, and low yellowing.
B-296	Aliphatic polyurethane acrylate	Fast curing, chemical resistance, yellowing resistance, impact resistance
B-296M	Polyurethane acrylate	Fast curing, resistant to polar solvents, yellowing-resistant, and impact-resistant.
B-301	Aromatic polyurethane acrylate	Fast curing, excellent toughness, and good sandability.
B-302	Aromatic polyurethane acrylate	Fast curing, high strength, excellent toughness, and good grindability.
B-368	Aliphatic polyurethane acrylate	Good toughness, excellent leveling, excellent bend resistance, and excellent heat resistance.
B-529	Polyester acrylate	Excellent adhesion, low shrinkage, and good resin compatibility.
B-609	Aliphatic polyurethane acrylate	Fast curing, high hardness, scratch resistance, and chemical resistance.
Dentistry
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-100M	Bisphenol A epoxy acrylate	Low viscosity, high hardness, high gloss, and high body.
B-113	Bisphenol A epoxy acrylate	High hardness, high gloss, high fullness, containing 20% TPGDA.
B-276H	Aliphatic polyurethane acrylate	High hardness, fast curing, excellent toughness, and low yellowing.
B-296	Aliphatic polyurethane acrylate	Fast curing, chemical resistance, yellowing resistance, impact resistance
B-296M	Polyurethane acrylate	Fast curing, resistant to polar solvents, yellowing-resistant, and impact-resistant.
B-301	Aromatic polyurethane acrylate	Fast curing, excellent toughness, and good sandability.
B-302	Aromatic polyurethane acrylate	Fast curing, high strength, excellent toughness, and good grindability.
B-368	Aliphatic polyurethane acrylate	Good toughness, excellent leveling, excellent bend resistance, and excellent heat resistance.
B-376	Aliphatic polyurethane acrylate	LED yellowing is minimal, and the nail polish formulation exhibits excellent stability.
B-609	Aliphatic polyurethane acrylate	Fast curing, high hardness, scratch resistance, and chemical resistance.
B-79D	Polyester acrylate	High hardness, low yellowing, and high evaporation efficiency at elevated temperatures.
Casting
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B-79D	Polyester acrylate	High hardness, low yellowing, and high evaporation efficiency at elevated temperatures.
Resilience
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-210D	Aliphatic polyurethane acrylate	Fast curing, low heat of reaction, and excellent toughness.
B-286	Aliphatic polyurethane acrylate	Low heat generation, excellent toughness, wear resistance, and impact resistance.
B-296M	Polyurethane acrylate	Fast curing, resistant to polar solvents, yellowing-resistant, and impact-resistant.
Elasticity
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-268M	Aliphatic polyurethane acrylate	Good flexibility, excellent adhesion, superior plating performance, and strong hiding power.
B-296	Aliphatic polyurethane acrylate	Fast curing, chemical resistance, yellowing resistance, impact resistance
B-39	Aliphatic polyurethane acrylate	Low viscosity, good flexibility, and low volatility.
B-450-2	Aliphatic polyurethane acrylate	Low curing shrinkage, excellent flexibility, and good tensile strength and elasticity.
B-451	Aliphatic polyurethane methacrylate	Good stretchability, low shrinkage, and excellent flexibility.
High transparency
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-296	Aliphatic polyurethane acrylate	Fast curing, chemical resistance, yellowing resistance, impact resistance
B-376	Aliphatic polyurethane acrylate	LED yellowing is minimal, and the nail polish formulation exhibits excellent stability.
Environmental protection
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-296SW	Aliphatic polyurethane acrylate	Yellowing resistance, impact resistance, bio-based content > 40%
Monomer Recommendation
Product Model/English Abbreviation	Product Name/Product Type	Product Features
BM1211 (HPMA)	Hydroxypropyl methacrylate	HEMA-free, high strength, low irritation, and high adhesion
BM2223 (TPGDA)	Dipropylene glycol diacrylate	Good flexibility and low volatility
BM3231 (TMPTA)	Trimethylolpropane triacrylate	High crosslink density, high hardness, high gloss, and excellent wear resistance.
BM3235 (PET3A)	Pentaerythritol triacrylate	Fast curing, high crosslink density, high hardness, and chemical resistance.
BM3380 (3EO-TMPTA)	Pentaerythritol triacrylate	More flexible and less irritating than TMPTA.

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The process of using UV 3D printing

Investigating the Physical Properties of UV 3D Printing