Preparation Of Anti-Ultraviolet Light Aging Polyurethane Acrylate-Based Light-Curing Composite Coating And Its Coating Performance

In recent years,as more and more countries and regions pay attention to environmental protection and sustainable development,green technology is also attracting much attention.UV curing technology as a green and efficient coating technology has also been developed rapidly.However,UV-curable coatings currently available on the market are mostly used in indoor environments such as paper,wood,and furniture,etc.In order to make their applications more extensive,it is necessary to develop a UV-curable coating suitable for outdoor weathering.In this thesis,four composite urethane acrylates were prepared as the matrix of UV-curable coatings by designing orthogonal experiments with two-functional urethane acrylates（PUA2）as the main base and four-functional urethane acrylates（PUA4）and six-functional urethane acrylates（PUA6）as the complementary base,and graphene and graphitic phase carbon nitride（g-C₃N₄）were added into the composite urethane acrylates to prepare UV-curable composite coatings.The main studies are as follows:（1）The curing time and mechanical properties,etc.of urethane acrylates with different functionalities were tested separately,and the results showed that PUA 2 had a curing time of705 s,hardness of H,and adhesion of grade 1;PUA 4 had a curing time of 598 s,hardness of H,and adhesion of grade 1;PUA 6 had a curing time of 543 s,hardness of H,and adhesion of grade 1.Through orthogonal experiments,four resin systems A₁B₀C₅,A₁B₁C₄,A₂B₂C₂and A₂B₄C₀were obtained,where A₁B₀C₅indicates 50%PUA 2 content,0 PUA 4 content and 50%PUA 6 content;A₁B₁C₄indicates 50%PUA 2 content,10%PUA 4 content and 40%PUA 6content;A₂B₂C₂indicates 60%PUA 2 content,20%PUA 4 content,and 20%PUA 6 content;A₂B₄C₀indicates 60%PUA 2 content,40%PUA 4 content,and 0 PUA 6 content.The curing time of these four resin ratios is between 300 s～500 s,the adhesion is all 0 grade,and the pencil hardness is between H～2 H.（2）Melamine was used as the reaction monomer to prepare g-C₃N₄by thermal polymerization,and then different contents of g-C₃N₄were added to four composite resins,A₁B₀C₅,A₁B₁C₄,A₂B₄C₀,and A₂B₂C₂.The curing time,hardness,adhesion,gloss,tensile strength,impact resistance test,thermal stability,water resistance,acid and alkali resistance,heat aging and light aging resistance tests.The results showed that the three groups of coatings,A₁B₀C₅-0.1 wt%,A₁B₁C₄-0.1 wt%,and A₂B₂C₂-0.3 wt%,had curing times ranging from 300 s to 360 s,hardnesses from 2 H to 3 H,adhesion grades from 0 to 1,tensile strengths from 25 to35 MPa,and impact strengths from 34 KJ/m²to 36 KJ/m².The addition of g C₃N₄reduces the gloss loss rate by 4%～5%,and there is no significant change in the decomposition temperature of the coating,and the water resistance,acid and alkali resistance,heat aging and light aging resistance are good.（3）The curing time,hardness,adhesion,gloss,impact test,tensile strength,thermal stability,water resistance,acid and alkali resistance,heat aging resistance and light aging resistance of the composite urethane acrylate coatings with different contents of graphene were prepared and studied by adding different contents of graphene to the four composite resins,A₁B₀C₅,A₁B₁C₄,A₂B₄C₀and A₂B₂C₂.Testing.The results showed that the three groups of coatings,A₁B₀C₅-0.1 wt%,A₂B₂C₂-0.1 wt%,and A₂B₄C₀-0.1 wt%,had curing times between280 s and 300 s,hardnesses between 2 H and 3 H,adhesion grades of 0,tensile strengths between 12 and 17 MPa,and impact strengths between 36 KJ/m²and 37K J/m².the addition of graphene reduced the gloss loss rate was reduced by 4%～5%,and the decomposition temperature of the coating did not change significantly,and the water resistance,acid and alkali resistance,heat aging resistance and light aging resistance were good.