Production of composites articles composed of thin layers

• US 20060035034A1
• Filed: 11/11/2002
• Published: 02/16/2006
• Est. Priority Date: 11/13/2001
• Status: Active Grant

• Current Assignee: Huntsman Advanced Materials Americas, Inc.
• Original Assignee: Huntsman Advanced Materials BV (Huntsman Corporation)
• Inventors: Zhao, Yong, Barny, Stefan, Studer, Peggy Diane, Matsumoto, Yonetatsu, Patel, Ranjana Changanbhai
• Granted Patent: US 7,416,764 B2
• Time in Patent Office: Days
• US Class Current: 427/487
• CPC Class Codes: B29C 64/106 using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material
• CPC Class Codes: B29C 64/112 using individual droplets, e.g. from jetting heads
• CPC Class Codes: B33Y 10/00 Processes of additive manufacturing
• CPC Class Codes: B33Y 70/00 Materials specially adapted for additive manufacturing
• CPC Class Codes: B42D 2033/20 Coloured material; Pigments or inks
• CPC Class Codes: B42D 2033/24 Reliefs or indentations
• CPC Class Codes: B42D 2033/46 with electrical circuitry
• CPC Class Codes: B42D 25/00 Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof printing processes to produce identification or security features B41M3/14
• CPC Class Codes: B42D 25/29 Securities; Bank notes
• CPC Class Codes: B42D 25/324 Reliefs
• CPC Class Codes: B42D 25/328 Diffraction gratings; Holograms
• CPC Class Codes: B42D 25/333 Watermarks

Abstract

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.

Claims

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) a diluent for the resin, said diluent consisting of 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 μ

m.

2. ) A method as claimed in claim 1, wherein said film comprises a stack of at least two layers.

3. ) A method as claimed in claim 2, wherein the properties of at least two layers in the stack are different.

4. ) A method as claimed in claim 1, wherein the resin is curable.

5. ) A method as claimed in claim 4, wherein the curable resin is a photosetting resin.

6. ) A method as claimed in claim 5, wherein the curable resin is selected from the group of resins curable by electromagnetic radiation and consisting of cyclic ether compounds, cyclic lactones, cyclic acetal compounds, cyclic thioether compounds, spiroorthoester compounds and vinyl compounds and the composition further includes at least one cationic photo-initiator salt.

7. ) A method as claimed in claim 4, wherein the curable resin is selected from the group of resins curable by radicals and consisting of acrylates, methacrylates, allyl urethane, urethane acrylates, epoxy-acrylates, epoxy-anhydrides and unsaturated polyester compounds, and the composition further includes at least one radical photoinitiator.

8. ) A method as claimed in claim 4, wherein the curable resin is selected from the group of resins curable by undergoing photo-dimerisation or a Diels Alder reaction.

9. ) A method as claimed in claim 1, wherein the composition comprises 5 to 80%, by weight, of the diluent.

10. ) A method as claimed in claim 1, wherein the composition comprises 20 to 60%, by volume, of the diluent.

11. ) A method as claimed in claim 1, wherein different compositions are deposited and the different compositions form visual and/or machine-readable information such as a photograph, a photorefractive image or a fluorescent image.

12. ) A method as claimed in claim 1, which includes removing the substrate from under the lowest layer.

13. ) A method as claimed in claim 1, wherein the said resin comprises liquid crystals and the film includes a liquid crystal alignment layer under the said liquid crystals layer.

14. ) A method as claimed in claim 13, 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.

15. ) A method as claimed in claim 13, wherein the liquid crystal alignment layer orientates the liquid crystals in the liquid crystal layer in two or more different directions.

16. ) A method as claimed in claim 13, and further comprising cross-linking the liquid crystals to an extent sufficient to maintain the birefringence of the liquid crystals.

17. ) A method as claimed in claim 13, 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, e.g. butanediol diacrylate, hexanediol diacrylate, isobomyl acrylate, phthalic acid mono hydroxyethyl acrylate, N-vinyl pyrrorydinone, tetrahydrofurfuryl acrylate, methyl methacrylate, propyleneglycol diacrylate, triethyleneglycol acrylate, neopentylglycol diacrylate, cyclohexyl acrylate, lauryl acrylate, most preferably, benzyl acrylate and phenoxyethyl acrylates.

18. ) A method as claimed in claim 13, wherein the curable diluent is an acrylate or methacrylate containing at least one aromatic ring.

19. ) A method as claimed in claim 1, wherein the curable diluent has a weight average molecular weight of less than 300 daltons.

20. ) A method as claimed in claim 1, wherein the curable diluent has a functionality of at least 2.

21. ) A method as claimed in claim 1, wherein the liquid composition has a viscosity of not greater than 70 cps at the temperature at which the droplets are directed onto the substrate.

22. ) A method as claimed in claim 1, wherein the droplets are directed onto the substrate by at least one inkjet.

23. ) A method as claimed in claim 1, wherein the at least one layer has a thickness of less than 5 μ

m.

24. ) An article comprising a film, e.g. a security device, made by the process of claim 1.