Transitorially erasable ink compositions and writing instruments containing same

Patent metadata

Field	Value
Publication number	US-9809722-B2
Application number	US-201514788320-A
Country	US
Kind code	B2
Filing date	Jun 30, 2015
Priority date	Jun 30, 2015
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

The disclosure provides transitorially erasable ink compositions, including an aliphatic hydrocarbon solvent, a rubber dissolved in the aliphatic hydrocarbon solvent, a hydrophilic pigment, and a surfactant. The disclosure further provides methods of preparing transitorially erasable ink compositions and writing instruments comprising transitorially erasable ink compositions. The disclosed erasable ink compositions write well, have strong color and erase easily transitorially, and demonstrate color stability.

First claim

What is claimed:

1. An erasable ink composition, comprising:
an aliphatic hydrocarbon solvent;
a rubber dissolved in the aliphatic hydrocarbon solvent;
a hydrophilic pigment; and
a surfactant.

2. The ink composition of claim 1 , wherein the pigment is provided in an amount between about 5 wt. % and about 50 wt. %, based on the total weight of the ink.

3. The ink composition according to claim 1 , wherein the rubber is provided in an amount between about 10 wt. % to about 50 wt. %, based on the total weight of the ink.

4. The ink composition according to claim 1 , wherein the solvent is provided in an amount between about 15 wt. % to about 90 wt. %, based on the total weight of the ink.

5. The ink composition according to claim 1 , wherein the surfactant is provided in an amount between about 2 wt. % and about 20 wt. %, based on the total weight of the ink.

6. The ink composition according to claim 1 , wherein the aliphatic hydrocarbon solvent comprises at least one of aliphatic petroleum naphtha, naphtha blends, mixtures of hydrotreated isoparaffins with naphthenics having low levels of aromatics, mixtures of hydrotreated isoparaffins with cycloparaffins having low levels of aromatics, and oil compatible plasticizers.

7. The ink composition according to claim 1 , wherein the hydrophilic pigment comprises at least two hydrophilic groups selected from the group consisting of amide, amine, hydroxyl, carboxyl, alkoxy, carbonyl, esters, ethers, salts of the foregoing, and combinations of the foregoing.

8. The ink composition according claim 1 , wherein the hydrophilic pigment is selected from the group consisting of easy-to-disperse-in-water (EDW) pigment preparations, pigments treated for water based inks or coatings, polar and hydrophilic inorganic pigments, and combinations thereof.

9. The ink composition according to claim 1 , wherein the composition is substantially free of water.

10. The ink composition according claim 9 , wherein the composition comprises less than 8 wt. % water, based on the total weight of the ink composition.

11. The ink composition according to claim 1 , wherein the hydrophilic pigment is a dry powdery pigment.

12. The ink composition according to claim 1 , wherein the surfactant is at least one selected from the group consisting of water-in-oil emulsifiers, pigment dispersants, and combinations thereof.

13. The ink composition according to claim 1 , further comprising less than about 8 wt. %, based on the total weight of the ink, of a hydrophilicity enhancing agent selected from the group consisting of water, glycerol, and combinations thereof.

14. The ink composition according to claim 1 , further comprising up to about 5 wt. %, based on the total weight of the ink, of a hydrophobicity enhancing agent and/or a rheology modifier.

15. The ink composition according to claim 1 , the ink composition having a viscosity in a range of about 1 cps to about 2,000,000 cps.

16. A writing instrument comprising the ink composition according to claim 1 .

17. The writing instrument of claim 16 , wherein the writing instrument is a ball-point pen and the ink is under positive pressure in the range of 15 to 100 psi.

18. A method of making an erasable ink composition comprising:
combining an aliphatic hydrocarbon solvent, a rubber, a surfactant and a hydrophilic pigment; and
mixing the solvent, rubber, surfactant, and hydrophilic pigment to provide a homogeneous dispersion, thereby forming the erasable ink composition.

19. The ink composition according to claim 1 , wherein the aliphatic hydrocarbon solvent is provided in an amount between about 20 wt. % to about 50 wt. %, based on the total weight of the ink.

20. The ink composition according to claim 1 , wherein the hydrophilic pigment is provided in an amount in a range of about 5 wt. % to about 10 wt. %, based on the total weight of the ink.

Assignees

• Sanford Lp

Inventors

• Zhu Jiandong
• Kwan Wing Sum Vincent

Classifications

• C09D11/18

  specially adapted for ball-point writing instruments · CPC title

• C09D11/16 Primary

  Writing inks · CPC title

• B43K7/03

  pressurised, e.g. by gas · CPC title

• C09D107/00

  Coating compositions based on natural rubber · CPC title

• B43K5/00

  Pens with ink reservoirs in holders, e.g. fountain-pens (nibs or writing-points with ink reservoirs B43K1/01; ball-point pens B43K7/00; pens with writing-points other than nibs or balls B43K8/00; multiple-point writing implements B43K27/00) · CPC title