Three-dimensionally printed lens elements

A three-dimensional printing system for forming a lens element, the three-dimensional printing system comprising:

• a fluid ejector loaded or loadable with a fusing agent to eject the fusing agent onto a powder bed of build material, the fusing agent separate from the build material and consisting of a liquid vehicle and from about 0.5 wt % to about 20 wt % of a UV radiation absorber having a D50 particle size of from about 30 nm to about 1000 nm, wherein the liquid vehicle consists of water and optionally an organic cosolvent an non-ionic ethoxylated surfactant, or a combination thereof, and wherein the UV radiation absorber is:
• a triazine radiation absorber selected from the group consisting of 2,4-bis(2,4-dimethylphenyl)-6-(2-hydroxy-4-octyloxyphenyl)-1,3,5-triazine, 2,4-bis(2,4-dimethylphenyl)-6-(2-hydroxy-4-isooctyloxyphenyl)-1,3,5-triazine, 2,4-bis(2,4-dimethyl phenyl)-6-(2-hydroxy-4-methoxy phenyl)1,3,5-triazine, 2-(2-hydroxy-4-hexyloxyphenyl)-4,6-bis(phenyl)-1,3,5-triazine, 2-(2-hydroxy-4-methoxyphenyl)-4,6-bis(phenyl)-1,3,5-triazine, 2,4-bis(2-hydroxy-4-methoxyphenyl)-6-ethyl mercaptan-1,3,5-triazine, and 2,2′-[6-(4-methoxyphenyl)-1,3,5-triazine-2,4-diyl]bis{5-[(2-ethylhexyl)oxy]phenol}, and a combination thereof;
• or
• a benzotriazole radiation absorber selected from the group consisting of 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol, 2-(2H-benzotriazol -2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, 2-(2H-benzotriazol-2-yl)-4,6-bis (1-methyl-1-phenylethyl)phenol, 2-tert-butyl-6-(5-chloro-2H-benzotriazol-2-yl)-4-methylphenol, 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol, 2-(2H -benzotriazol-2-yl)-4,6-di-tert-pentylphenol, 2,2′-methylenebis[6-(2H -benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol], 2-(2H-benzotriazol-2-yl) -6-dodecyl-4-methylphenol, and a combination thereof;
• or
• terephthalylidene dicamphor sulfonic acid;
• or
• milled avobenzone particles,
• wherein the fusing agent exhibits an absorbance of from about 0.3 to about 2 at a radiation wavelength of from about 340 nm to about 415 nm;
• and
• a UV energy source that emits electromagnetic radiation at an energy level of from about 2 W/cm2 to about 50 W/cm2, wherein the electromagnetic radiation includes the radiation wavelength.

A method for three-dimensional printing a lens element, the method comprising:

• iteratively applying individual build material layers including from about 80 wt % to 100 wt % of thermoplastic polyamide elastomeric particles having a D50 particle size of from about 10 μm to about 150 μm to a powder bed;
• based on a three-dimensional object model, iteratively and selectively dispensing a fusing agent onto the individual build material layers, wherein the fusing agent is separate from the build material and consists of includes an aqueous liquid vehicle and from about 0.5 wt % to about 20 wt % of a UV radiation absorber having a D50 particle size of from about 30 nm to about 1000 nm, wherein the liquid vehicle consists of water and optionally an organic cosolvent, a non-ionic ethoxylated surfactant, or a combination thereof, and wherein the UV radiation absorber is:
• a triazine radiation absorber selected from the group consisting of 2,4-bis(2,4-dimethylphenyl)-6-(2-hydroxy-4-octyloxyphenyl)-1,3,5-triazine, 2,4-bis(2,4-dimethylphenyl)-6-(2-hydroxy-4-isooctyloxyphenyl)-1,3,5-triazine, 2,4-bis(2,4-dimethyl phenyl)-6-(2-hydroxy-4-methoxy phenyl)1,3,5-triazine, 2-(2-hydroxy-4-hexyloxyphenyl)-4,6-bis(phenyl)-1,3,5-triazine, 2-(2-hydroxy-4-methoxyphenyl)-4,6-bis(phenyl)-1,3,5-triazine, 2,4-bis(2-hydroxy-4-methoxyphenyl)-6-ethyl mercaptan-1,3,5-triazine, and 2,2′-[6-(4-methoxyphenyl)-1,3,5-triazine-2,4-diyl]bis{5-[(2-ethylhexyl)oxy]phenol}, and a combination thereof;
• or
• a benzotriazole radiation absorber selected from the group consisting of 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol, 2-(2H-benzotriazol -2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, 2-tert-butyl-6-(5-chloro-2H-benzotriazol-2-yl)-4-methylphenol, 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol, 2-(2H -benzotriazol-2-yl)-4,6-di-tert-pentylphenol, 2,2′-methylenebis[6-(2H -benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol], 2-(2H-benzotriazol-2-yl) -6-dodecyl-4-methylphenol, and a combination thereof;
• or
• terephthalylidene dicamphor sulfonic acid;
• or
• milled avobenzone particles,
• wherein the fusing agent exhibits an absorbance of from about 0.3 to about 2 at a radiation wavelength of from about 340 nm to about 415 nm;
• and
• iteratively exposing the powder bed to electromagnetic radiation that includes the radiation wavelength at an energy level of from about 2 W/cm2 to about 50 W/cm2 for a time duration of from about 0.1 second to about 10 seconds to selectively fuse the thermoplastic polyamide elastomeric particles in contact with the UV radiation absorber at the individual build material layers resulting in a transparent or translucent lens element.