Hybrid marking instrument and writing ink composition
AssigneeParker Pen (Benelux) B.V.
InventorsJohn Thompson, Philip Wallis
Life of this patent
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Abstract
A writing ink composition having a pseudoplasticity index value between about 0.02 and 0.18, a low-shear viscosity between about 25,000 and 120,000 cP, and a high-shear viscosity between about 6 and 26 cP can be used in a hybrid, ball-point marking instrument which combines advantageous features of both paste-ink and liquid-ink ballpens. The writing ink can be prepared using a colloid milling procedure.
Claims25
A writing ink composition comprising (i) an amount of at least one pseudoplastic resin and (ii) a carrier medium for said resin, said amount being such that said ink composition has:
- (a) a pseudoplasticity index value between about 0.02 and 0.18;
- (b) a viscosity at 0.1 sec.sup.-1 shear rate between about 25,000 and 120,000 cP;
- and
- (c) a viscosity at 10,000 sec.sup.- shear rate between about 6 and 26 cP.
A method for preparing a writing ink composition comprising (i) an amount of at least one pseudoplastic resin and (ii) a carrier medium for said resin, said method comprising the steps of (1) adding a predetermined amount of said pseudoplastic resin to an organic liquid to produce a slurry of said resin in said organic liquid;
- (2) mixing said slurry with a solvent comprising at least one from the group consisting of water and an organic solvent in which said resin is soluble, said mixing being carried out under sufficiently high shear conditions such that a partially solvated fine dispersion of the resin is produced;
- and then (3) adding a colorant to said partially solvated fine dispersion and subjecting said partially solvated fine dispersion to hydraulic shear such that a fully solvated lyophilic sol of said resin is produced, said lyophilic sol having (a) a pseudoplasticity index value between about 0.02 and 0.18, (b) a viscosity at 0.1 sec.sup.-1 shear rate between about 25,000 and 120,000 cP and (iii) a viscosity at 10,000 sec.sup.-1 shear rate between about 6 and 26 cP.
Dependencies are inferred from the claim text.