Method of inkjet printing onto aligners

Patent metadata

Field	Value
Publication number	US-10336102-B2
Application number	US-201815945224-A
Country	US
Kind code	B2
Filing date	Apr 4, 2018
Priority date	Apr 4, 2017
Publication date	Jul 2, 2019
Grant date	Jul 2, 2019

Abstract

Provided herein are methods of obtaining good photocured-ink adhesion to low surface energy materials. The methods have greatly improved adhesion of photocured ink on low surface energy materials, including those that are subjected to high humidity or wet environments. The methods take into account the glass transition temperature (T g ) of the materials and the onset for the glass transition temperature, including ink applied to an exposed surface of the material at an elevated temperature that is close to the T g of the material. The ink is allowed to sit briefly or soak, such as for more than 1 second, before the ink is cured. The ink may be photocured. Furthermore, the methods do not require solvents or surface treatment, including plasma or corona treatments, to obtain good ink adhesion.

First claim

I claim:

1. A method of printing ink to a low surface energy material, the method comprising:
heating a low surface energy material to an elevated temperature that is greater than or equal to an onset temperature associated with a glass transition temperature of said low surface energy material;
applying a printable ink to an exposed surface of said heated low surface energy material;
soaking said applied printable ink and said heated low surface energy material for a soak time to facilitate penetration of said applied printable ink into the heated low surface energy material; and
curing said printable ink applied to said exposed surface after said soak time to durably adhere said cured printable ink to said low surface energy material when said cured printable ink applied to said exposed surface is immersed in a liquid at a liquid temperature substantially near human body temperature for at least approximately twenty-four (24) hours.

2. The method of claim 1 , wherein said elevated temperature is less than or equal to the glass transition temperature plus 70° C.

3. The method of claim 1 , wherein heating said low surface energy material comprises applying radiative heat or convective heat to said low surface energy material.

4. The method of claim 1 , wherein heating said low surface energy material comprises exposing said low surface energy material to infrared light having wavelengths that are substantially matched to an absorbance spectrum of said low surface energy material, to substantially confine heating to said exposed surface, thereby avoiding a bulk material property change to said low surface energy material.

5. The method of claim 1 , wherein heating said low surface energy material is substantially confined to a printing area of said exposed surface or to a geometric shape having a border area in which said applied printable ink is confined.

6. The method of claim 1 , wherein said heating step comprises heating of said printable ink.

7. The method of claim 1 , wherein said heating is by one or more of:
infrared radiation;
microwave radiation;
contact heating with a heating element;
ultrasonic radiation;
radiofrequency heating;
heated air; and
heated liquid.

8. The method of claim 1 , wherein said elevated temperature is between 70° C. and 130° C. for said low surface energy material having the glass transition temperature greater than or equal to 130° C.

9. The method of claim 1 , wherein the property of durably adhered is characterized by a tape test of adhesion.

10. The method of claim 1 , wherein said soak time is less than or equal to 30 seconds.

11. The method of claim 1 , wherein said soak time is selected to achieve a desired maximum penetration depth of said applied printable ink into said low surface energy material.

12. The method of claim 1 , wherein applying said printable ink comprises ink-jet printing of said printable ink.

13. The method of claim 1 , wherein said exposed surface is not pretreated prior to said applying step.

14. The method of claim 1 , further comprising pretreating said exposed surface before said applying step and optionally before said heating step.

15. The method of claim 1 , wherein said low surface energy material comprises a plastic.

16. The method of claim 15 , wherein said plastic is selected from the group consisting of: a polyolefin, a polyester, a polyacrylate, polymethacrylates, polystyrenes, polypropylenes, polyethylenes, polyethylene terephthalates, poly lactic acid, polyurethanes, epoxide polymers, polyethers, poly(vinyl chlorides), polysiloxanes, polycarbonates, polyamides, poly acrylonitriles, polybutadienes, poly(cycloolefins), and copolymers.

17. The method of claim 1 , wherein said low surface energy material comprises a polymer.

18. The method of claim 1 , wherein said printable ink comprises a pigmented resin.

19. The method of claim 1 , wherein said curing comprises exposing said applied printable ink to electromagnetic radiation.

20. The method of claim 1 , wherein said printable ink comprises a dual cure system having a cationic component and a free radical component.

21. The method of claim 1 , wherein said printable ink has a low molecular weight component that diffuses into said low surface energy material to a depth from said exposed surface.

22. The method of claim 1 , wherein curing said printable ink occurs after said printable ink penetrates to a depth below said exposed surface, so that after said curing said printable ink is at least partially embedded in said low surface energy material.

23. The method of claim 1 , wherein said method is substantially solvent-free.

24. The method of claim 1 , further comprising coating said applied printable ink with an overcoat layer.

25. The method of claim 1 , further comprising thermoforming the low surface energy material and the heating of the low surface energy material corresponds to a residual elevated temperature from the thermoforming process.

26. The method of claim 1 , wherein the glass transition temperature and the onset temperature of the low surface energy material is above room temperature.

27. A dental aligner having one or more printed regions by the method of claim 1 .

28. A system for durably adhering cured printable ink onto an exposed surface of a low surface energy material, the system comprising:
said low surface energy material;
said printable ink;
a printer configured to apply said printable ink to said exposed surface of said heated low surface energy material when said low surface energy material is within an elevated temperature range;
a substrate configured to:
hold said low surface energy material to facilitate soaking of said applied printable ink and said low surface energy material for a soak time to facilitate penetration of said applied printable ink into said heated low surface energy material; and facilitate curing of said printable ink applied to said exposed surface after said soak time to durably adhere said cured printable ink to said low surface energy material when said cured printable ink applied to said exposed surface is immersed in a liquid at a liquid temperature substantially near human body temperature for at least approximately twenty-four (24) hours, and is durably adhered to said exposed surface as characterized by a tape test of adhesion.

29. The system of claim 28 , wherein said printer is configured to make a dental aligner from a polymer.

Assignees

• Align Technology Inc

Inventors

• Cole Michael Christopher

Classifications

• A61C7/08

  Mouthpiece-type retainers {or positioners, e.g. for both the lower and upper arch (arch-shaped medicament applicators for teeth or gums A61C19/063; mouthguards for protecting the teeth of sportsmen A63B71/085)} · CPC title

• C09D11/322

  Pigment inks · CPC title

• C09D11/101

  Inks specially adapted for printing processes involving curing by wave energy or particle radiation, e.g. with UV-curing following the printing · CPC title

• B41M5/0064

  on plastics, horn, rubber, or other organic polymers · CPC title

• B41M7/009

  using thermal means, e.g. infrared radiation, heat · CPC title