METHOD OF FORMULATING INK HAVING MINIMAL VISIBLE COLORATION

• US 20110226156A1
• Filed: 05/30/2011
• Published: 09/22/2011
• Est. Priority Date: 07/10/2006
• Status: Active Grant

• Current Assignee: BASF SE
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Hall, Lachlan Everett, Silverbrook, Kia, Indusegaram, Sutharsiny, Vonwiller, Simone Charlotte, Starling, Scott Matthew, Ridley, Damon Donald, Gonzaga, Graciel
• Granted Patent: US 8,110,030 B2
• Time in Patent Office: Days
• US Class Current: 106/31.49
• CPC Class Codes: C09B 47/0673 having alkyl radicals linked directly to the Pc skeleton; having carbocyclic groups linked directly to the skeleton
• CPC Class Codes: C09B 47/0678 having-COOH or -SO3H radicals or derivatives thereof directly linked to the skeleton
• CPC Class Codes: C09B 47/26 Amide radicals
• CPC Class Codes: C09B 69/04 of anionic dyes with nitrogen containing compounds
• CPC Class Codes: C09D 11/328 characterised by dyes
• CPC Class Codes: Y10T 428/24802 Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]
• CPC Class Codes: Y10T 428/24934 including paper layer

Abstract

A method of formulating an aqueous ink having minimal visible coloration. The method includes the steps of: providing an aqueous ink formulation containing a sulfonated water-soluble IR-absorbing naphthalocyanine dye having a central metal atom moiety; and adjusting a pH of the formulation to a pH value in the range of 4 to 6.5 so as to minimize visible coloration of the formulation.

Claims

1. A method of formulating an aqueous ink having minimal visible coloration, said method comprising the steps of:

providing an aqueous ink formulation comprising a sulfonated water-soluble IR-absorbing naphthalocyanine dye having a central metal atom moiety; and

adjusting a pH of said formulation to a pH value in the range of 4 to 6.5 so as to minimize visible coloration of the formulation.

2. The method of claim 1, wherein said pH is adjusted using a buffer formulation is buffered.

3. The method of claim 1 wherein said pH is adjusted using at least one base B, wherein a conjugate acid BH⁺ of said at least one base B has a pK_a of between 4 and 9.

4. The method of claim 3, wherein the conjugate acid BH⁺ of said at least one base B has a pK_a of between 4.5 and 8.

5. The method of claim 3, wherein said pH is adjusted using a nitrogen base, an oxyanion base or mixtures thereof

6. The method of claim 5, wherein said nitrogen base is a nitrogen-containing C_5-12 heteroaryl base.

7. The method of claim 6, said nitrogen base is imidazole or pyridine.

8. The method of claim 1, wherein said dye has a λ

_max of 800 nm or more.

9. The method of claim 1, wherein said dye is of formula (II):

10. The method of claim 9, wherein A¹ is selected from the group consisting of:

—

OH and —

Cl.

11. The method of claim 9, wherein R¹ and R² are both hydrogen.