×

Method of making and the composition for an initially erasable ink for a ball point writing instrument

  • US 4,349,639 A
  • Filed: 03/26/1981
  • Issued: 09/14/1982
  • Est. Priority Date: 03/26/1981
  • Status: Expired due to Fees
First Claim
Patent Images

1. The method of making an ink composition which is characterized by initial erasability by ordinary pencil erasers of a trace thereof when applied by a ball-point writing instrument to an absorbent paper-like writing surface and which trace thereafter develops permanence, said method comprising the steps of:

  • (a) providing a pre-pigmented elastomer component in which pigment is substantially homogeneously distributed throughout and aggregated onto molecular chains of elastomer component;

    (b) dispersing the pre-pigmented elastomer component in a solvent system, the solvent system being present in amount sufficient to provide an ink composition having a viscosity in the range of 1-4×

    106 cps and comprising a volatile component having a boiling point less than about 180°

    C. and which contributes to initial erasability of an applied trace of the ink composition and an essentially non-volatile component which contributes to development of permanence of the applied trace; and

    (c) controlling initial erasability of the ink composition and capability of subsequently developing permanence when applied as a trace to the absorbent writing surface with the ball-point writing instrument by selecting, for the elastomer component of step (a), elastomeric materials which exhibit predetermined molecular weight distribution over a wide molecular weight range and by milling the pigment into the elastomer component in the absence of the solvent system to provide the pre-pigmented elastomer component of step (a), and by selecting, for the essentially non-volatile component of step (b), a liquid having a boiling point in the range 180°

    -300°

    C. and a viscosity in the range 1-15 cps.

View all claims
  • 4 Assignments
Timeline View
Assignment View
    ×
    ×