[Literature Interpretation] Is it feasible to synthesize UV-curable polyurethane acrylate using a solvent-free one-pot method?

Keywords: castor oil one-pot solvent-free polyurethane acrylate UV curable coating

Background introduction

UV curing technology is widely used in coatings, inks, adhesives and other industries, and has the advantages of high efficiency, energy saving, economy, effectiveness, and environmental protection

Most vegetable oils require chemical modification of triglycerides and double bonds before they can synthesize polymers

The Yang Zhuohong team of the Key Laboratory of Bio-based Materials and Energy of the Ministry of Education, South China Agricultural University, innovatively proposed a solvent-free one-pot synthesis method of castor oil-based polyurethane acrylate (COPUA) from the perspective of industrialization

research content

1.

The chemical structures of IBOA, HEMA and TPGDA are shown in Figure 1

2.

COPUA was simply synthesized using castor oil (CO), isophorone diisocyanate (IPDI), hydroxyethyl acrylate (HEA) and isobornyl acrylate (IBOA) as raw materials, as shown in Figure 2

3.

Table 1 shows the formulas for preparing different UV-curable films, denoted as F1-F7
.
Add COPUA, active diluent and photoinitiator into a 25 mL brown glass bottle in proportion, heat and stir in the dark for 1 h, and then use a 500μm mold to uniformly wet coat the tinplate and glass plate
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Then under the UV curing machine, the wet film is converted into a solid film with a 5 kW high-pressure mercury lamp, the irradiation distance is 10 cm, and the irradiation time is 40 seconds
.

Results discussion

1.
Structural analysis of CO, CO-NCO and COPUA

2.
Viscosity and volume shrinkage

3.
Swelling analysis and gel content

4.
Mechanical properties

5.
Thermomechanical analysis

6.
Thermal stability

7.
Coating performance

in conclusion

In summary, the synthesis conditions and process of COPUA are simple, but the performance is excellent
.
More importantly, the synthesis time of COPUA is only 6h, and the reaction temperature is not high
.
No post-treatment is required at the end of the reaction and can be used directly
.
Therefore, the solvent-free one-pot synthesis of COPUA has broad application prospects
.
FT-IR and 1h-NMR indicated that COPUA was successfully synthesized
.
Using COPUA, HEMA and TPGDA to prepare cured film formulations, the viscosity, mechanical properties, thermal stability, dynamic thermodynamic properties, gel rate and coating properties of the cured film were studied
.
The results show that the pure COPUA cured film and other samples have excellent performance
.
The long fatty chain of castor oil makes the cured film have excellent flexibility and solvent resistance.
The high glass transition temperature and mechanical properties make it widely used
.
Its excellent comprehensive performance makes it possible for COPUA to replace petroleum-based oligomers
.
The experimental results of COPUA show that it has a great possibility of commercialization, which provides a new idea for the industrial production of vegetable oil-based products
.

References: Li P, Chu Z, Chen Y, etal.
One-pot and solvent-free synthesis of castor oil-based polyurethaneacrylate oligomers for UV-curable coatings applications[J].
Progress in OrganicCoatings, 2021,159:106398.