Erasable ink for a writing implement
View Patent ↗At least one embodiment of the present invention relates to an erasable ink composition particularly useful in a writing instrument for simultaneous the appearance of a graphite pencil. The composition of the present invention comprises a solvent system, a rubber and a pigment. The solvent system used in the present invention comprises an organic ester and a component selected from the group consisting of an optionally substituted cycloalkane, an optionally substituted cycloalkanone, an optionally substituted cycloalkene, or mixtures thereof. A sufficient amount of the solvent system is present so that the erasable ink composition will flow in a writing instrument. Preferably, the erasable ink composition of the present invention includes a pigment comprising graphite and carbon black. Finally, the erasable ink composition optionally includes a plasticizer, a liquid butene, or one or more additives selected from the group consisting of a corrosion inhibitor, a flow enhancing compound, and mixtures thereof.
1. An erasable ink composition comprising:
a solvent system including:
a component selected from the group consisting of an optionally substituted cycloalkane, an optionally substituted cycloalkene, an optionally substituted cycloalkanone, and mixtures thereof; and
isobutyl butyrate;
a rubber; and
a pigment; the solvent system present in a sufficient amount that the erasable ink composition will flow in a writing implement.
2. The erasable ink composition of claim 1 wherein the pigment is graphite powder, carbon black powder, or mixture thereof.
3. The erasable ink composition of claim 1 wherein the pigment is present in an amount of 2% to 25% of the total weight of the erasable ink composition.
4. The erasable ink composition of claim 1 wherein a sufficient amount of the solvent system is present so that the erasable ink composition has a viscosity from 20,000 cP to 60,000 cP at 25° C.
5. The erasable ink composition of claim 1 wherein the solvent system comprises a component selected from the group consisting of an optionally substituted cycloalkane having a 4 to 7 member ring, an optionally substituted cycloalkanone having a 4 to 7 member ring, an optionally substituted cycloalkene having a 4 to 7 member ring, and mixtures thereof; and an organic ester.
6. The erasable ink composition of claim 1 wherein the solvent system comprises:
a component selected from the group consisting of cyclohexane, cyclohexanone, and mixtures thereof; and
isobutyl butyrate.
7. The erasable ink composition of claim 1 wherein the solvent system is present in an amount of 25% to 55% of the total weight of the erasable ink composition.
8. The erasable ink composition of claim 7 wherein the solvent system includes:
cyclohexane present in an amount of 40% to 80% of the total weight of the solvent system; and
isobutyl butyrate present in an amount of 20% to 60% of the total weight of the solvent system.
9. The erasable ink composition of claim 1 wherein the rubber is a natural or synthetic rubber.
10. The erasable ink composition of claim 1 wherein the rubber is a synthetic rubber which is a copolymer of styrene and isoprene.
11. The erasable ink composition of claim 1 wherein the natural or synthetic rubber is a present in an amount of 10% to 40% of the total weight of the erasable ink composition.
12. The erasable ink composition of claim 1 further comprising a component selected from the group consisting of:
a plasticizer;
an additive selected from the group consisting of a corrosion inhibitor, a flow enhancing compound, and mixtures thereof;
a liquid butene polymer; and
mixtures thereof.
13. The erasable ink composition of claim 12 wherein the additive comprise a corrosion inhibitor.
14. The erasable ink composition of claim 13 wherein the corrosion inhibitor comprises a phosphate ester present in an amount of 0.5% to 6% of the total weight of the erasable ink composition.
15. The erasable ink composition of claim 12 wherein the additive comprises a flow enhancing material.
16. The erasable ink composition of claim 15 wherein the flow enhancing material is a mineral oil present in an amount of 0.5% to 12% of the total weight of the erasable ink composition.
17. The erasable ink composition of claim 12 wherein the liquid butene polymer comprises a component selected from the group consisting of polybutene, a copolymer of butene and isobutene, and mixtures thereof.
18. The erasable ink composition of claim 12 wherein the plasticizer is at least one phthalic ester selected from the group consisting a dibutyl phthalate, dioctyl phthalate, and mixtures thereof.
19. The erasable ink composition of claim 18 wherein the at least one phthalic ester is present in an amount of 3% to 25% of the total weight of the erasable ink composition.
20. The erasable ink composition of claim 18 wherein the at least one phthalic ester is a phthalic ester mixture comprising:
dibutyl phthalate in an amount of 10% to 40% of the total weight of the phthalic ester mixture; and
dioctyl phthalate in an amount of 60% to 90% of the total weight of the phthalic ester mixture.
21. An erasable ink composition comprising:
a solvent system including:
a component selected from the group consisting of an optionally substituted cycloalkane, an optionally substituted cycloalkene, an optionally substituted cycloalkanone, and mixtures thereof; and
isobutyl butyrate;
at least one phthalic ester selected from the group consisting a dibutyl phthalate, dioctyl phthalate, and mixtures thereof;
a rubber;
an additive selected from the group consisting of a corrosion inhibitor, a flow enhancing compound, and mixtures thereof;
a liquid butene polymer; and
a pigment comprising graphite and carbon black.
22. The erasable ink composition of claim 21 wherein the solvent system present in a sufficient amount that the erasable ink composition will flow in a writing implement and the erasable ink composition has a viscosity from 20,000 cP to 60,000 cP at 25° C.
23. The erasable ink composition of claim 21 wherein the solvent system comprises a component selected from the group consisting of an optionally substituted cycloalkane having a 4 to 7 member ring, an optionally substituted cycloalkanone having a 4 to 7 member ring, an optionally substituted cycloalkene having a 4 to 7 member ring, and mixtures Thereof; and an organic ester.
24. The erasable ink composition of claim 21 wherein the solvent system comprises:
a component selected from the group consisting of cyclohexane, cyclohexanone, and mixtures thereof; and
isobutyl butyrate.
25. The erasable ink composition of claim 21 wherein the solvent system is present in an amount of 25% to 55% of the total weight of the erasable ink composition.
26. The erasable ink composition of claim 21 wherein the graphite is present in an amount of about 2% to about 20% of the total weight of the erasable ink composition and the carbon black is present in an amount of about 20% to about 20% of the total weight of the erasable ink composition.
27. An erasable ink composition comprising:
a solvent system including:
cyclohexane present in an amount from about 40% to about 80% of the total weight of the solvent system; and
isobutyl butyrate present in an amount from about 20% to about 60% of the total weight of the solvent system;
at least one phthalic ester selected from the group consisting a dibutyl phthalate, dioctyl phthalate, and mixtures thereof;
a rubber;
an additive selected from the group consisting of a corrosion inhibitor, a flow enhancing compound, and mixtures thereof;
a liquid butene polymer; and
a pigment comprising graphite and carbon black; the solvent system present in a sufficient amount that the erasable ink composition will flow in a writing implement and the erasable ink composition has a viscosity from 20,000 cP to 60,000 cP at 25° C.
28. The erasable ink composition of claim 27 wherein the solvent system is present in an amount of 25% to 55% of the total weight of the erasable ink composition.