Erasable inks containing thermoplastic block copolymers
AssigneeThe Gillette Company
InventorRobert F. Farmer, III
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Abstract
An erasable ink containing a thermoplastic block copolymer, pigment particles, and a solvent. In a preferred embodiment, an erasable ink requiring little or no pressurization is provided by employing a mixture of radial and linear block copolymers and a mixed solvent system falling within a specific range of solubility parameter. Polybutene and poly-alpha-methylstyrene are preferred additives to decrease smearing tendency.
Claims5
An erasable ink for use in a ball-point writing instrument consisting essentially of a pigmented organic solvent solution containing a thermoplastic block copolymer having an arrangement of A (thermoplastic) and B (rubbery) blocks selected from the class consisting of ABA, (AB).sub.n X and (--AB)--.sub.n ;
- in which said thermoplastic blocks are selected from the class consisting of styrene, ester and urethane blocks;
- in which said rubbery blocks are selected from the class consisting of butadiene, isoprene and ethylene-butylene blocks;
- in which the ratio of said rubbery blocks to said thermoplastic blocks is from 60:40 to 90:10;
- in which the solubility parameter of said organic solvent is from about 7 to about 10.5;
- and containing an effective amount up to about 10% by weight of said solution of an additive to increase erasability selected from the class consisting of polybutenes and poly-alpha-methylstyrene.
Dependencies are inferred from the claim text.