Liquid developer compositions with a vinyl polymeric gel
AssigneeNashua Corporation
InventorsNorman T. Veillette, Charles H. C. Pian
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Abstract
Disclosed is a developer composition which in use exhibits improved depletion characteristics and produces copies of high image density. The developer comprises an organic carrier containing a pigment system, a charge control agent, and a "gelatex" which acts as a fixitive and a dispersant. The gelatex comprises a carrier-insoluble vinyl polymer and a multiply-branched, vinyl polymer which physically entraps or entangles the carrier-insoluble polymer and is on the borderline of solubility in the carrier. The gelatex component is present in the carrier as a stable dispersion and is substantially uniformly depleted as multiple copies are produced, resulting in a significantly reduced rate of image density deterioration as multiple copies are produced.
Claims17
A liquid developer composition for developing an electrostatic latent image on the surface of an image bearing member, said composition comprising:
- an organic liquid carrier having a resistivity greater than 10.sup.9 ohm-cm and a dielectric constant less than 3;
- a charge control agent;
- a pigment;
- and
- a gelatex consisting essentially of
- a covalently cross-linked, vinyl polymeric gel on the borderline of solubility in said carrier and comprising a three-dimensional, multiply-branched molecular framework comprising a major amount of monomer units selected from the group consisting of:
- ##STR3## where X is H or CH.sub.3 and Y is C.sub.n H.sub.2n+1, where 8.ltoreq.n.ltoreq.20 and a trace amount of monomer units having 2-5 vinyl moieties attached by covalent bonds;
- and
- a carrier-insoluble vinyl polymeric latex physically held within said framework comprising a major amount of monomer units selected from the group consisting of:
- ##STR4## where X is H or CH.sub.3 and Z is C.sub.n H.sub.2n+1, where 1.ltoreq.n.ltoreq.6.
In a method of creating an image, the improvement comprising applying under electrostatic control to an electrostatic image bearing member so as to selectively deposit a coating thereon, a liquid electrostatic developer comprising:
- an organic liquid carrier having a resistivity greater than 10.sup.9 ohm-cm and a dielectric constant less than 3;
- a charge control agent;
- a pigment;
- and
- a gelatex consisting essentially of
- a covalently cross-linked, vinyl polymeric gel on the borderline of solubility in said carrier and comprising a three-dimensional, multiply-branched molecular framework comprising a major amount of monomer units selected from the group consisting of:
- ##STR5## where X is H or CH.sub.3 and Y is C.sub.n H.sub.2n+1, where 8.ltoreq.n.ltoreq.20 and a trace amount of monomer units having 2-5 vinyl moieties attached by covalent bonds;
- and
- a carrier-insoluble vinyl polymeric latex physically held within said framework comprising a major amount of monomer units selected from the group consisting of:
- ##STR6## where X is H or CH.sub.3 and Z is C.sub.n H.sub.2n+1, where 1.ltoreq.n.ltoreq.6.
A liquid negative developer composition for developing an electrostatic latent image on the surface of an image bearing member, said composition comprising:
- an organic liquid carrier having a resistivity greater than 10.sup.9 ohm-cm and a dielectric constant less than 3;
- a charge control agent comprising a copolymer of 10-50 parts of a lower alkyl (C.sub.2 -C.sub.6) vinyl ether and 50-90 parts of a vinyl chloride;
- a pigment;
- and
- a gelatex consisting essentially of
- a covalently cross-linked, vinyl polymeric gel on the borderline of solubility in said carrier and comprising a three-dimensional, multiply-branched molecular framework having a major amount of monomer units selected from the group consisting of:
- ##STR7## where X is H or CH.sub.3 and Y is C.sub.n H.sub.2n+1, where 8.ltoreq.n.ltoreq.20 and
- a carrier-insoluble vinyl polymeric latex physically held within said framework and having a major amount of monomer units selected from the group consisting of:
- ##STR8## where X is H or CH.sub.3 and Y is C.sub.n H.sub.2n+1, where 1.ltoreq.n.ltoreq.6.
A method of manufacturing a liquid developer composition comprising the steps of:
- A. reacting in a reaction medium at least one monovinyl monomer with a trace amount of monomer units having 2-5 covalently attached vinyl moieties to produce a gel-like three-dimensional, multiply-branched vinyl polymeric molecule on the borderline of solubility in organic liquid carriers having a resistivity greater than 10.sup.9 ohm-cm and a dielectric constant less than 3;
- B. reacting in the presence of the product of step A at least one monovinyl monomer to produce a polymeric latex, insoluble in said carriers, and physically held within the framework of the multiply-branched product of step A;
- C. adding a charge control agent and a pigment to said reaction medium;
- D. milling the product of step C to produce a substantially homogeneous dispersion;
- and
- E. diluting the product of step D with an organic liquid carrier having a resistivity greater than 10.sup.9 ohm-cm and a dielectric constant less than 3.
Dependencies are inferred from the claim text.