Three dimensional printing materials and method for making a 3D printed article

Abstract

Methods and materials are disclosed for making three dimensional articles via 3d printing. The methods can include printing both electrically insulating and electrically conducting portions, transparent, reflective or opaque portions, transparent portions having different refractive indices, portions of different colors, and where the various deposited portions are UV or heat curable, and optionally comprise particles, such as metallic particles in electrically conductive portions and ceramic particles in electrically insulating portions. A variety of 3D articles can be made, such as transparent articles such as eyeglasses, or electronics articles such as portions of smartphones, tablets or the like.

Claims

1. A three dimensional printing process comprising, concurrently or sequentially depositing electrically conductive and electrically insulating materials so as to form a 3D printed article; wherein both the electrically conductive and electrically insulating materials comprise a siloxane polymer that is cured upon deposition by electromagnetic radiation or heat.

2. The process of claim 1, wherein the electrically conductive siloxane polymer is cured by heat and the electrically insulating siloxane polymer is cured by UV light.

3. The process of claim 2 or 3, wherein the electrically conductive siloxane polymer is cured by heat and UV light.

4. The process of any of the preceding claims, wherein the electrically conductive siloxane polymer comprises particles.

5. The process of any of the preceding claims, wherein the particles are metal particles.

6. The process of any of the preceding claims, wherein the electrically insulating siloxane polymer comprises particles.

7. The process of any of the preceding claims, wherein the particles in the electrically insulating siloxane polymer are nitride or oxide particles.

8. The process of any of the preceding claims, wherein the coefficient of thermal expansion difference between the electrically insulating and electrically conducting materials in the 3D printed article is less than 10%.

9. The process of any of the preceding claims, wherein the coefficient of thermal expansion difference is less than 5%.

10. The process of any of the preceding claims, wherein the particles in the electrically insulating siloxane comprise an oxide of silicon, zinc, aluminum, yttrium, ytterbium, tungsten, titanium silicon, titanium, antimony, samarium, nickel, nickel cobalt, molybdenum, magnesium, manganese, lanthanide, iron, indium tin, copper, cobalt aluminum, chromium, cesium or calcium.

11. The process of any of the preceding claims, wherein the particles in the electrically insulating siloxane comprise silica, quartz, alumina, aluminum nitride, aluminum nitride coated with silica, barium sulfate, alumina trihydrate, or boron nitride.

12. The process of any of the preceding claims, wherein the particles in the electrically insulating siloxane are nitride particles and comprise aluminum nitride, tantalum nitride, boron nitride, titanium nitride, copper nitride, molybdenum nitride, tungsten nitride, iron nitride, silicon nitride, indium nitride, gallium nitride or carbon nitride.

13. The process of any of the preceding claims, wherein the particles in the electrically conductive siloxane comprise gold, silver, copper, platinum, palladium, indium, iron, nickel, aluminum, carbon, cobalt, strontium, zinc, molybdenum, titanium, tungsten, silver plated copper, silver plated aluminum, bismuth, tin, or alloys or combinations thereof.

14. The process of any of the preceding claims, wherein a first group and second group of particles are provided within the electrically conductive siloxane, wherein the first group is different from the second group based on average particle size, shape, and/or composition.

15. The process of any of the preceding claims, wherein the first group of particles has an average particle size of greater than 500 nm, and the second group of particles has an average particle size of less than 200 nm.

16. The process of any of the preceding claims, wherein the electrically insulating siloxane comprises particles.

17. The process of any of the preceding claims, wherein the electrically insulating siloxane comprises first and second groups of particles, where the first group is different from the second group based on average particle size, shape and/or composition.

18. The process of any of the preceding claims, wherein the electrically insulating siloxane is transmissive to visible light such that at least 85% of light incident thereon is transmitted.

19. The process of any of the preceding claims, wherein the 3D article is a modular smartphone, tablet or laptop.

20. An article formed by the process of any of claims 1 to 19.

21. A 3D printed article, comprising: a first portion that is electrically insulating and comprises a siloxane polymeric material; a second portion that is electrically conductive and comprises a siloxane polymeric material.

22. The article of claim 21, wherein the second portion comprises metal particles.

23. The article of claim 21 or 22, wherein the first portion comprises ceramic particles.

24. The article of any of claims 21 to 23, wherein the electrically insulating first portion is a light transmissive portion that transmits at least 85% of visible light incident thereon.

25. The article of any of claims 21 to 24, wherein the electrically insulating first portion comprises subportions that are of different colors.

26. The article of any of claims 21 to 25, wherein the electrically insulating first portion comprises subportions that are light transmissive with different refractive indices.

27. The article of any of claims 21 to 26, wherein the electrically insulating portions are electrical connections within an electronics device.

28. The article of any of claims 21 to 27, wherein the electronics device is a smartphone, tablet or laptop.

29. The article of any of claims 21 to 28, wherein both the first and second portions comprise particles.

30. The article of any of claims 21 to 29, wherein the particles in the first portion are different from the particles in the second portion.

31. A 3D printed article comprising: a cured siloxane material having therein a first group of particles and a second group of particles, wherein the first group is different from the second group based on average particle size, shape or particle material.

32. A 3D printed article comprising: a first portion that transmits at least 85% of visible light incident thereon; a second portion that transmits at least 85% of visible light incident thereon; wherein the first portion and the second portion have different refractive indices.

33. The article of claim 32, wherein the first portion and second portion are directly contacting each other.

34. A 3D printed article comprising: a first portion that is light transmissive and transmits at least 85% of visible light incident thereon, and wherein the first portion has an index of refraction less than 1.4 at 632.8 nm wavelength and has an optical birefringence less than 0.01.

35. The article of claim 34, wherein the refractive index is less than 1.3.

36. The article of claim 34 or 35 wherein the first portion comprises particles.

37. The article of any of claims 34 to 36, wherein the particles have an average particle size of less than 400 nm.

38. The article of any of claims 34 to 36, wherein the particles have an average particle size of less than 100 nm.

39. A 3D printed article comprising: a light transmissive portion that transmits at least 85% of visible light incident thereon, and wherein the portion has an index of refraction greater than 1.55 at 632.8 nm wavelength and has an optical birefringence less than 0.01.

40. The article of claim 39, wherein the index of refraction is 1.65 or higher.

41. The article of claim 39 or 40, wherein the index of refraction is 1.70 to 1.95.

Description

COMPOSITION EXAMPLES

[0098] The following composition examples are given by way of illustration and are not intended to be limitative.

[0099] Comp. example 1, Silver filled adhesive: A siloxane polymer with epoxy as a crosslinking functional group (18.3 g, 18.3%), silver flake with average size (D50) of 4 micrometer (81 g, 81%), 3-methacrylatepropyltrimethoxysilane (0.5 g, 0.5%) and King Industries K-PURE CXC-1612 thermal acid generator (0.2%) where mixed together using high shear mixer. The composition has a viscosity of 15000 mPas.

[0100] Comp. example 2, Alumina filled adhesive: A siloxane polymer with epoxy as a crosslinking functional group (44.55, 44.45%), aluminium oxide with average size (D50) of 0.9 micrometer (53 g, 53%), 3-methacrylatepropyltrimethoxysilane (1 g, 1%), Irganox 1173 (1 g, 1%) and King Industries K-PURE CXC-1612 thermal acid generator (0.45 g, 0.45%) where mixed together using three roll mill. The composition has a viscosity of 20000 mPas.

[0101] Comp. example 3, BN filled adhesive: A siloxane polymer with epoxy as a crosslinking functional group (60 g, 60%), boron nitride platelet with average size (D50) of 15 micrometer (35 g, 35%), Irganox 1173 (1.3 g, 1.3%), 2-(3,4-Epoxycyclohexyl)ethyltrimethoxysilane (3.4 g, 3.4%) and King Industries K-PURE CXC-1612 thermal acid generator (0.3 g, 0.3%) where mixed together using three roll mill. The composition has a viscosity of 25000 mPas.

[0102] Comp. example 4, Translucent material: A siloxane polymer with methacrylate as a functional group (89 g, 89%), fumed silica with average size (D50) of 0.007 micrometer (5 g, 5%), Irganox 1173 (2 g, 2%) and Irgacure 917 photoinitiator (4 g, 4%) where mixed together using three roll mill. The composition has a viscosity of 25000 mPas.

[0103] In view of the disclosed methods and materials, a stable composition is formed. The composition may have one part that is a siloxane polymer having a [SiOSiO].sub.n repeating backbone, with alkyl or aryl groups thereon, and functional cross-linking groups thereon, and another part that is particles mixed with the siloxane material, wherein the particles have an average particle size of less than 100 microns, the particles being any suitable particles such as metal, semi-metal, semiconductor or ceramic particles. The composition as shipped to customers may have a molecular weight of from 300 to 10,000 g/mol, and a viscosity of from 1000 to 75000 mPa-sec at 5 rpm viscometer.

[0104] The viscous (or liquid) siloxane polymer is substantially free of OH groups, thus providing increased shelf-life, and allowing for storing or shipping at ambient temperature if desired. Preferably, the siloxane material has no OH peak detectable from FTIR analysis thereof. The increased stability of the formed siloxane material allows for storage prior to use where there is a minimal increase in viscosity (cross-linking) during storage, such as less than 25% over the period of 2 weeks, preferably less than 15%, and more preferably less than 10% over a 2 week period stored at room temperature. And, the storage, shipping and later application by the customer can be all performed in the absence of a solvent (except for possible trace residues that remain after drying to remove the solvent), avoiding the problems of solvent capture in the layer later formed in the final product, shrinkage during polymerization, mass loss over time during device usage, etc. No substantial cross-linking occurs during shipping and storage, without the application of heat preferably greater than 100 C or UV light.

[0105] When the composition is deposited and polymerized, e.g. by the application of heat or UV light, very small shrinkage or reduction in mass is observed. In FIG. 6, the x-axis is time (in minutes), the left y axis is the mass of the layer in terms of % of the starting mass, and the right y-axis is temperature in Celsius. As can be seen in FIG. 6, a siloxane particle mixture as disclosed herein is heated rapidly to 150 C, then held at 150 C for approximately 30 minutes. In this example, the siloxane particle has a SiO backbone with phenyl group and epoxy groups, and the particles are silver particles. The mass loss is less than 1% after heat curing for over this time period. Desirably the mass loss is typically less than 4%, and generally less than 2%however in many cases the difference in mass of the siloxane particle composition between before and after curing is less than 1%. The curing temperature is generally at less than 175 C., though higher curing temperatures are possible. Typically the curing temperature will be at 160 C. or below, more typically at 150 C. or below. However lower curing temperatures are possible, such as at 125 C. or below.

[0106] Regardless of whether the 3D printed material is deposited as an electrically insulating layer, an electrically conductive layer, as a thermally conductive layer, a transparent layer, a light reflecting layer, opaque or colored layer etc., once the composition is deposited and polymerized and hardened as desired, the siloxane particle layer or pattern is thermally very stable. As an example, heating the in situ material after hardening by heat or UV polymerization up to 600 C. at a ramp rate of 10 C. increase per minute, a mass loss of less than 4.0%, preferably less than 2.0%, e.g. less than 1.0% is observed at both 200 C. and 300 C. (typically a mass loss of less than 0.5% is observed at 200 C., or a mass loss of less than 0.2% at 200 C. is observed). At 300 C., a mass loss of less than 1% is observed, or more particularly less than 0.6%. Similar results can be observed by simply heating the polymerized material for 1 hour at 200 C., or at 300 C. Results of less than 1% mass loss by heating the polymerized deposited material at 375 C or more for at least 1 hour are possible. Even at temperatures of greater than 500 C., a mass loss of 5% or less is observed. Such a thermally stable material is desirable, particularly one as disclosed herein that can be deposited at low temperatures (e.g. less than 175 C., preferably less than 150 C., or less than 130 C. at e.g. 30 min curing/baking time), or that can be polymerized by UV light.

[0107] As can be seen from the above, various 3D articles can be printed with siloxane materials. Transparent articles, or portions or articles, with or without particles therein, reflective articles, and opaque articles are possible. In addition, electrically insulating and electrically conducting articles, or portions or articles, can be printed. A mixture of transparent materials, e.g. with different refractive indices, or a mixture of reflective and transparent materials, can be used for 3D printing an article. Colors can also be added to the siloxane materials being printed. It is possible to print continuously, or pixel by pixel (voxel by voxel). It is also possible to first print entirely one siloxane material (e.g one color, or e.g. electrically insulating) followed by entirely another color or e.g. electrically conductive.

[0108] It is also possible to print layer by layer, where first all of a first color (or electrically insulating) is printed in a layer, followed by all of a second color (or electrically conductive) is printed in that layer. For faster printing, it is desirable to have multiple print heads such that the different materials (different colors, different refractive indices, different conductivities, etc.) are printed at the same time, or immediately sequentially such that when the reciprocating or rotary platform of the 3D printing machine need not repeat movement over the same area.

[0109] The foregoing is illustrative of example embodiments and is not to be construed as limiting thereof. Although a few example embodiments have been described, those skilled in the art will readily appreciate that many modifications are possible in example embodiments without materially departing from the novel teachings and advantages. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the claims. Therefore, it is to be understood that the foregoing is illustrative of various example embodiments and is not to be construed as limited to the specific embodiments disclosed, and that modifications to the disclosed embodiments, as well as other embodiments, are intended to be included within the scope of the appended claims.

[0110] The following embodiments can be particularly mentioned.

[0111] 1. A three dimensional printing process comprising, [0112] concurrently or sequentially depositing electrically conductive and electrically insulating materials so as to form a 3D printed article; [0113] wherein both the electrically conductive and electrically insulating materials comprise a siloxane polymer that is cured upon deposition by electromagnetic radiation or heat.

[0114] 2. The process of embodiment 1, wherein the electrically conductive siloxane polymer is cured by heat and the electrically insulating siloxane polymer is cured by UV light.

[0115] 3. The process of embodiment 1 or 2, wherein the electrically conductive siloxane polymer comprises particles, such as metal particles.

[0116] 4. The process of any of the preceding embodiments, wherein the electrically insulating siloxane polymer comprises particles, selected from nitride or oxide particles.

[0117] 5. The process of any of the preceding embodiments, wherein the particles in the electrically insulating siloxane comprise silica, quartz, alumina, aluminum nitride, aluminum nitride coated with silica, barium sulfate, alumina trihydrate, or boron nitride or the particles in the electrically insulating siloxane are nitride particles and comprise aluminum nitride, tantalum nitride, boron nitride, titanium nitride, copper nitride, molybdenum nitride, tungsten nitride, iron nitride, silicon nitride, indium nitride, gallium nitride or carbon nitride.

[0118] 6. The process of any of the preceding embodiments, wherein the particles in the electrically conductive siloxane comprise gold, silver, copper, platinum, palladium, indium, iron, nickel, aluminum, carbon, cobalt, strontium, zinc, molybdenum, titanium, tungsten, silver plated copper, silver plated aluminum, bismuth, tin, or alloys or combinations thereof.

[0119] 7. The process of any of the preceding embodiments, wherein a first group and second group of particles are provided within the electrically conductive siloxane, wherein the first group is different from the second group based on average particle size, shape, and/or composition, the first group of particles having an average particle size of greater than 500 nm, and the second group of particles having an average particle size of less than 200 nm.

[0120] 8. The process of any of the preceding embodiments, wherein the electrically insulating siloxane comprises first and second groups of particles, where the first group is different from the second group based on average particle size, shape and/or composition.

[0121] 9. An article formed by the process of any of embodiments 1 to 8.

[0122] 10. A 3D printed article, comprising: [0123] a first portion that is electrically insulating and comprises a siloxane polymeric material; [0124] a second portion that is electrically conductive and comprises a siloxane polymeric material.

[0125] 11. The article of embodiment 10, wherein the second portion comprises metal particles and the first portion comprises ceramic particles.

[0126] 12. The article of embodiments 10 or 11, wherein the electrically insulating first portion is a light transmissive portion that transmits at least 85% of visible light incident thereon.

[0127] 13. A 3D printed article comprising a cured siloxane material having therein a first group of particles and a second group of particles, wherein the first group is different from the second group based on average particle size, shape or particle material.

[0128] 14. A 3D printed article comprising: [0129] a first portion that transmits at least 85% of visible light incident thereon; [0130] a second portion that transmits at least 85% of visible light incident thereon; [0131] wherein the first portion and the second portion have different refractive indices.

[0132] 15. The article of embodiment 14, wherein the first portion and second portion are directly contacting each other.

[0133] 16. A 3D printed article comprising: [0134] a first portion that is light transmissive and transmits at least 85% of visible light incident thereon, and [0135] wherein the first portion has an index of refraction less than 1.4 at 632.8 nm wavelength and has an optical birefringence less than 0.01.

[0136] 17. The article of embodiment 16, wherein the refractive index is less than 1.3 and wherein the first portion comprises particles, for example particles of an average particle size of less than 400 nm, such as less than 100 nm.

[0137] 18. A 3D printed article comprising: [0138] a light transmissive portion that transmits at least 85% of visible light incident thereon, and wherein the portion has an index of refraction greater than 1.55 at 632.8 nm wavelength and has an optical birefringence less than 0.01, for example wherein the index of refraction is 1.65 or higher, such as 1.70 to 1.95.

INDUSTRIAL APPLICABILITY

[0139] The present methods can include printing both electrically insulating and electrically conducting portions, transparent, reflective or opaque portions, transparent portions having different refractive indices, portions of different colors, and where the various deposited portions are UV or heat curable, and optionally comprise particles, such as metallic particles in electrically conductive portions and ceramic particles in electrically insulating portions. A variety of 3D articles can be made, such as transparent articles such as eyeglasses, or electronics articles such as portions of smartphones, tablets or the like.

[0140] CITATION LIST

Patent Literature

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