Liquid formulations for coating and printing substrates

Abstract

A method is disclosed of preparing a liquid formulation for application as a deposit on a substrate. The method includes the steps of providing a liquid having a first viscosity in a non-evaporative state; and adding an amine-acid adduct to the liquid to form a mixture having a second viscosity greater than the first viscosity. The amine-acid adduct is evaporative such that the amine-acid adduct is substantially completely removed from the deposit in a functionally dry state.

Claims

1. A method of coating or printing a substrate with a liquid, said method comprising: providing a liquid including a conductive ink and having a first viscosity; providing an amine-acid adduct that includes amine; combining said liquid with said amine-acid adduct to form a mixture having a second viscosity greater than said first viscosity; applying said mixture as a deposit on the surface of the substrate; and drying the deposit to a functionally dry state in which said amine-acid adduct is substantially completely removed from said deposit.

2. The method of claim 1 wherein said amine-acid adduct comprises more than 10% by weight of said mixture.

3. The method of claim 1 wherein said amine-acid adduct is evaporative to a reduced level of less than about 0.2% by weight of said deposit.

4. The method of claim 3 wherein said reduced level is less than about 0.1% by weight of said deposit.

5. The method of claim 3 wherein said reduced level is less than about 0.01% by weight of said deposit.

6. The method of claim 3 wherein said reduced level is less than about 0.001% by weight of said deposit.

7. The method of claim 1, wherein said drying is achieved by a process selected from the group consisting of thermal drying, air drying, infrared drying, microwave drying and vacuum drying.

8. The method of claim 1 wherein said liquid includes a dispersion of nano particles.

9. The method of claim 8, wherein said nano particles are carbon nanotubes.

10. The method of claim 1, wherein said amine-acid adduct further includes a diluting acrylate.

11. The method of claim 1, wherein the amine-acid adduct includes propyl amine.

12. The method of claim 1, wherein the amine acid adduct includes butyl amine.

13. The method of claim 1, wherein the amine acid adduct includes CO.sub.2.

14. The method of claim 1, wherein the amine is a primary or secondary amine.

15. The method of claim 1, wherein the amine is selected from the group consisting of morpholine, N-ethyl-n-butyl amine, n-butyl amine, sec-butyl amine, t-butyl amine, n-propyl amine, n-pentyl amine, di-n-butylamine, N-methyl-n-butylamine, ethylene diamine, 2-amino-2-methyl-1-propanol and di methyl, ethanol amine.

16. The method of claim 1, wherein the amine-acid adduct further includes one of: carbon disulfide (CS.sub.2), hydrochloric acid (HCL), or a low boiling temperature organic acid.

17. The method of claim 16, wherein the low boiling temperature organic acid is one of: acetic acid, formic acid, or propionic acid.

18. The method of claim 1, wherein the liquid mixture comprises a hydrocarbon, water, or an alcohol.

19. The method of claim 1, wherein the amine-acid adduct is a carbamate or the carbonate wherein the carbamate or the carbonate is a viscosity control agent that alters the first viscosity of the liquid.

20. A method of coating or printing a substrate with a liquid, said method comprising: providing a liquid including carbon nanotubes and having a first viscosity; providing an amine-acid adduct that includes amine; combining said liquid with said amine-acid adduct to form a mixture having a second viscosity greater than said first viscosity; applying said mixture as a deposit on the surface of the substrate; and drying the deposit to a functionally dry state in which said amine-acid adduct is substantially completely removed from said deposit.

21. The method of claim 20 wherein said amine-acid adduct comprises more than 10% by weight of said mixture.

22. The method of claim 20 wherein said amine-acid adduct is evaporative to a reduced level of less than about 0.2% by weight of said deposit.

23. The method of claim 22 wherein said reduced level is less than about 0.1% by weight of said deposit.

24. The method of claim 22 wherein said reduced level is less than about 0.01% by weight of said deposit.

25. The method of claim 22 wherein said reduced level is less than about 0.001% by weight of said deposit.

26. The method of claim 20, wherein said drying is achieved by a process selected from the group consisting of thermal drying, air drying, infrared drying, microwave drying and vacuum drying.

27. The method of claim 20, wherein the amine-acid adduct includes propyl amine.

28. The method of claim 20, wherein the amine acid adduct includes butyl amine.

29. The method of claim 20, wherein the amine acid adduct includes CO.sub.2.

30. The method of claim 20, wherein the amine is a primary or secondary amine.

31. The method of claim 20, wherein the amine is selected from the group consisting of morpholine, N-ethyl-n-butyl amine, n-butyl amine, sec-butyl amine, t-butyl amine, n-propyl amine, n-pentyl amine, di-n-butylamine, N-methyl-n-butylamine, ethylene diamine, 2-amino-2-methyl-1-propanol and dimethyl, ethanol amine.

32. The method of claim 20, wherein the amine-acid adduct further includes one of: carbon disulfide (CS.sub.2), hydrochloric acid (HCL), or a low boiling temperature organic acid.

33. The method of claim 32, wherein the low boiling temperature organic acid is one of: acetic acid, formic acid, or propionic acid.

34. The method of claim 20, wherein the liquid mixture comprises a hydrocarbon, water, or an alcohol.

35. The method of claim 20, wherein the amine-acid adduct is a carbamate or the carbonate wherein the carbamate or the carbonate is a viscosity control agent that alters the first viscosity of the liquid.

36. A method of coating or printing a substrate with a liquid, said method comprising: providing a liquid including an optical coating material and having a first viscosity; providing an amine-acid adduct; combining said liquid with said amine-acid adduct to form a mixture having a second viscosity greater than said first viscosity; applying said mixture as a deposit on the surface of the substrate; and drying the deposit to a functionally dry state in which said amine-acid adduct is substantially completely removed from said deposit.

37. The method of claim 36 wherein said amine-acid adduct comprises more than 10% by weight of said mixture.

38. The method of claim 36 wherein said amine-acid adduct is evaporative to a reduced level of less than about 0.2% by weight of said deposit.

39. The method of claim 38 wherein said reduced level is less than about 0.1% by weight of said deposit.

40. The method of claim 38 wherein said reduced level is less than about 0.01% by weight of said deposit.

41. The method of claim 38 wherein said reduced level is less than about 0.001% by weight of said deposit.

42. The method of claim 36, wherein said drying is achieved by a process selected from the group consisting of thermal drying, air drying, infrared drying, microwave drying and vacuum drying.

43. The method of claim 36 wherein said liquid includes a dispersion of nano particles.

44. The method of claim 43, wherein said nano particles are carbon nanotubes.

45. The method of claim 36, wherein said amine-acid adduct further includes a diluting acrylate.

46. The method of claim 36, wherein the amine-acid adduct includes propyl amine.

47. The method of claim 36, wherein the amine acid adduct includes butyl amine.

48. The method of claim 36, wherein the amine is a primary or secondary amine.

49. The method of claim 36, wherein the amine is selected from the group consisting of morpholine, N-ethyl-n-butyl amine, n-butyl amine, sec-butyl amine, t-butyl amine, n-propyl amine, n-pentyl amine, di-n-butylamine, N-methyl-n-butylamine, ethylene diamine, 2-amino-2-methyl-1-propanol and dimethyl, ethanol amine.

50. The method of claim 36, wherein the amine-acid adduct further includes one of: carbon disulfide (CS.sub.2), hydrochloric acid (HCL), or a low boiling temperature organic acid.

51. The method of claim 50, wherein the low boiling temperature organic acid is one of: acetic acid, formic acid, or propionic acid.

52. The method of claim 36, wherein the liquid mixture comprises a hydrocarbon, water, or an alcohol.

53. The method of claim 36, wherein the amine-acid adduct is a carbamate or the carbonate wherein the carbamate or the carbonate is a viscosity control agent that alters the first viscosity of the liquid.

54. The method of claim 36, wherein the amine acid adduct includes CO.sub.2.

Description

DETAILED DESCRIPTION

(1) The present invention employs the amine carbamate as a viscosity control agent for a range of solutions/dispersions from hydrocarbons to alcohols to water. Primary and secondary amines are candidates; tertiary amines are not useful.

(2) The amines, when treated with CO.sub.2 form the amine carbamate (and with water can form the amine carbonate). This zwitter ion salt formed can, as is the case of fatty acid esters and salts, be used to alter the rheology of a liquid in which such salts are compatible.

(3) The use of amines, especially those that have a boiling point at about the temperature of that of the solvent or the continuous phase of a liquid mixture, allows the carbamate (carbonate) to break down (release CO.sub.2) and the amine to evaporate off with the other volatile components of the mixture. In the course of applying the mixture to a substrate and processing it to its functionally dried state, the carbamate (carbonate) is substantially completely removed, with any residue being as low as 0.2%, typically less than 0.1%, preferably less than 0.01%, and most preferably less than 0.001% by weight of the thus applied and processed mixture.

(4) Applications where this type of rheology control is advantageous include, for example: (a) Nanotechnology, where the elements being coated are often in very dilute concentration, but the coatings need a higher viscosity to allow even placement. This is of particular interest when dealing with carbon nanotubes, where viscosity control not only facilitates application, but also has a stabilizing effect in preventing the nanotubes from entangling in the carrier liquid, thus agglomerating and falling out of the carrier liquid before coating, discrete coating, or printing. (b) The application of optical coatings, e.g., for film based vision driven user interfaces (displays, touchscreens), clear protective coatings for graphics, etc., where clarity of the functionally dried deposit is a prime requirement. (c) Other contamination-sensitive coatings that are used in electronic product fabrication. For example, use of “ink jet” type of coatings (printing) used in placement of resist coatings; or adhesion treatments for discrete placement of conductive elements in a circuit.

(5) In the following examples, liquid mixtures were prepared using one or more of the following components: CNT Ink Concentrate (3000 ppm CNT) obtained from Eikos in Franklin, Mass. Solvent Ink Concentrate #7633-41P obtained from Raffi & Swanson in Wilmington, Mass. Diluting Acrylate IBOA (Isobornyl Acrylate) obtained from Surface Specialties UCB in Smyrna, Ga. UV Coating ECX 4019 obtained from Cognis Corporation in Ambler, Pa.

Example 1

(6) TABLE-US-00001 Conductive Ink WB Carbamate: sec-Butyl Amine 90 grams Water 10 grams CO.sub.2 Bubble through until viscosity 11,500-12,500 cP CNT Ink CNT Ink Concentrate  1% Formula: (3000 ppm CNT) Water 21% Solvent (IPA) 50% Carbamate 28% 100%  Starting viscosity of ink concentrate 30-100 cP Final viscosity of mixture 1500-2000 cP

Example 2

(7) TABLE-US-00002 Optical Coating Carbamate: n-Butyl Amine 50 grams Solvent 50 grams CO.sub.2 Bubble through until viscosity 10,000 cP Solvent Ink Formula: Solvent Ink Concentrate 10% Solvent 70% Carbamate 20% 100%  Starting viscosity of concentrate 100-200 cP Final viscosity of concentrate 1000-1200 cP

Example 3

(8) TABLE-US-00003 Optical Coating Carbamate: n-Propyl Amine 20 grams Diluting Acrylate 80 grams CO.sub.2 Bubble through until viscosity 10,000 cP UV Coating Formula: UV Coating 79% Carbamate 21% 100%  Starting viscosity of UV coating 200-250 cP Final viscosity of mixture 1500-1800 cP

(9) The mixtures of Examples 1-3 were applied to a clear polyester film using a Meyer drawdown rod and processed to their functionally dried state in a laboratory oven at 70° C. for one minute. The resulting dried deposits were tested for residual carbamate components using a pHydrion Insta-Check Surface pH Pencil (available from VWR International of West Chester, Pa., U.S.A.). In each case, the pH reading ranged between 5 and 6.

(10) Based on the definition of pH (the chemical fact that pH is the negative logarithmic function of the concentration of the hydrogen ion, written as the equation pH=−log [H.sup.+] from Holtzclaw et. al. General Chemistry, p. 459, 1984, D. C, Heath and Co., Lexington, Mass.), the higher the concentration of the hydrogen ion, the lower the pH. Any residual amine component of the carbamates would decrease the hydrogen ion concentration and thereby increase the pH as measured in this test.

(11) Using this method of calculation, and based on the pH readings recited above, the residual carbamate concentrations in the functionally dried residues of Examples 1-3 were determined to be in the range of 7.3×10.sup.−6%. To the extent present at such reduced levels, any residual carbamate was observed to have no significant adverse impact on the conductivity of the ink of Example 1, or on the clarity of the coatings of Examples 2 and 3.

(12) Zwitter ion adducts of amines can be formed with materials other than CO.sub.2. Carbon disulfide (CS.sub.2) also forms stable amine salts, as do hydrogen chloride (HCl) and low boiling temperature organic acids (e.g. acetic acid, formic acid, propionic acid). However, CO.sub.2 has the advantage of being of minimal toxicity and is a relatively weak acid, which may be a benefit to some of the coatings being treated.

(13) Another advantage is that few amine carbamates/carbonates are stable much above 100° C. Thus a CO.sub.2-based adduct, being easier to break down, has an excellent overall fugitive property.

(14) As an alternative to making an amine adduct and then adding the adduct to a coating (or printing) system, the amine may be added directly to the coating, followed by addition of the CO.sub.2, CS.sub.2, etc. so as to form the amine adduct in-situ. In all cases, upon drying, the amine carbamate would decarboxylate, and then the amine could be driven off. The temperature needed would depend on the amine and whether or not the regenerated amine was needed to play a roll in maintaining coating “wet out” during the drying process.

(15) The printed or coated mixtures of the present invention may be dried to their functionally dried state by various methods, e.g., thermal drying, air drying, infrared drying, microwave drying and vacuum drying.

(16) Amines useful in the present invention may be selected from the group listed below in Table 1.

(17) TABLE-US-00004 TABLE 1 Amine B.P. ° C. Morpholine 129 N-ethyl-n-butyl amine 91 n-butyl amine 78 sec-butyl amine 63 t-butyl amine 46 n-propyl amine 48 n-pentyl amine 104 di-n-butylamine 129 N-methyl-n-butylamine 91 Ethylene diamine 117 AMP (2 amino-2-methyl-1-propanol) 166 DMEA (dimethyl, ethanol amine) 135