Production of composites articles composed of thin layers
View Patent ↗A method is described of producing thin layers (below 10 μm in thickness) by directing droplets (preferably by inkjet printing techniques) onto precise locations on a substrate, the liquid of the droplets having a viscosity such that the droplets, on impact with the substrate, spread out to form relics on the substrate that are at least 1.4 times the diameter of the droplets in flight, adjacent droplets merging to form a continuous layer on the substrate. The droplets may have different compositions to form images within the layer. Successive layers may be added to built up a three dimensional structure whose properties can be tailored by the compositions used to build up a composite.
1. A method of forming a film comprising of at least one layer of at least one resin, which method comprises directing droplets of a liquid composition comprising:
a) the said at least one resin; and
b) at least one curable diluent onto an array of locations on a substrate, the liquid composition being such that the droplets, on impact with the substrate, spread out to form droplet relics on the substrate that have a diameter at least 1.4 times the diameter of the droplets in flight, such that adjacent droplets merge to form a continuous layer of substantially uniform thickness on the substrate; and curing the curable materials in the continuous layer to solidify the layer, wherein said composition contains substantially no non-curable diluent and wherein the layer has a thickness of less than 10 μm and
wherein the said resin comprises liquid cristals and the film includes a liquid crystal alignment layer under the said liquid crystal layer.
2. A method as claimed in claim 1 , wherein the liquid crystal alignment layer is deposited by directing droplets of a liquid onto the substrate and is photocured or photoisomerised under polarised light.
3. A method as claimed in claim 1 , wherein the liquid crystal alignment layer orientates the liquid crystals in the liquid crystal layer in two or more different directions.
4. A method as claimed in claim 1 , and further comprising cross-linking the liquid crystals to an extent sufficient to maintain the birefringence of the liquid crystals.
5. A method as claimed in claim 1 , wherein the curable diluent used to deposit the liquid crystal layer is an acrylate, a methacrylate, a vinyl ether, or a compound containing an allyl or a styryl group.
6. A method as claimed in claim 1 , wherein the curable diluent is an acrylate or methacrylate containing at least one aromatic ring.