Process for preparing deodorized resin for dry toner

Details Process for preparing deodorized resin for dry toner Process for preparing deodorized resin for dry toner

1996-12-26

1998-12-22

Lipman, Bernard

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

528491, 5263292, C08F 238

Patent

active

058521470

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The present invention relates to a process for preparing a deodorized resin for a dry toner. More particularly, it pertains to a process for preparing a deodorized resin for a dry toner, which comprises polymerizing an aromatic vinylic monomer and an acrylic monomer in the presence of a molecular weight-controlling agent, an initiator and an emulsifier using a two-step emulsion polymerization process to obtain a latex having a bimodal molecular weight distribution; and treating the latex with an oil-soluble peroxide.


BACKGROUND OF THE INVENTION

A binder resin for a copying machine toner should have a viscosity suitably adjusted to the copying speed of the machine; in particular, a toner for use in a high-speed copying machine requires a resin having a low viscosity and containing no gel. In order to have a low viscosity, the resin should have a sufficiently low molecular weight, and, to accomplish this, an excessive amount of molecular weight-controlling agent is usually added to the resin to lower its molecular weight. Because many of the molecular weight-controlling agents, e.g., mercaptans, release unpleasant sharp odors, the unreacted molecular weight-controlling agent remaining in the final product causes a toner to emit a bad smell. Unreacted monomers remaining in the resin are also considered to be the source of bad odors.
Hitherto, various methods for preparing a deodorized resin for a toner have been developed and reported.
U.S. Pat. No. 5,268,431 discloses an ozonizing method which comprises polymerizing diene monomer and styrene to obtain a copolymer and treating the copolymer with ozone to cut the double bond of the diene, thereby lowering the molecular weight of the copolymer without employing an excess amount of a molecular weight-controlling agent.
Japanese Patent No. 05-150545 discloses a process for preparing a deodorized resin by raising the reaction temperature after polymerization to bring the reactions of the foul smelling unreacted monomers to completion.
Japanese Patent No. 05-142860 discloses a process for preparing a deodorized resin by irradiating an electron beam on the residual monomers after polymerization, thereby generating radicals to complete the reaction of the monomers.
U.S. Pat. No. 5,342,722 reports a process for preparing a deodorized resin by using an odorless .alpha.-methylstyrene dimer as a molecular weight-controlling agent.
On the other hand, Japanese Patent No. 05-216272 discloses a process for preparing a deodorized toner by adding a terpene or a flavor to a resin for a toner.
However, the above methods have problems in that the reaction or work-up process is complicated, the process time unduly long, and/or an additional cost is incurred due to the use of a molecular weight-controlling agent having a low reactivity.
Therefore, there has continued to exist a need for a simple, effective process for the preparation of a deodorized resin for a dry toner.


SUMMARY OF THE INVENTION

Accordingly, it is a primary object of the present invention to provide a simple, effective process for the preparation of a deodorized resin for a dry toner.
In accordance with one aspect of the present invention, there is provided a process for preparing a deodorized resin for a dry toner, which comprises polymerizing an aromatic vinylic monomer and an acrylic monomer in the presence of a molecular weight-controlling agent, an initiator and an emulsifier using a two-step emulsion polymerization to obtain a latex having a bimodal molecular weight distribution; and treating the latex with an oil-soluble peroxide initiator.


DETAILED DESCRIPTION OF THE INVENTION

Generally, a binder resin for a toner is polymerized by any one of the conventional methods, e.g., an emulsion polymerization, a suspension polymerization, a solution polymerization or a bulk polymerization. In the present invention, a two-step emulsion polymerization method is employed.
The two-step emulsion polymerization of the present invention comprises a first step polymerization to obtain a hig

REFERENCES:
patent: 3928498 (1975-12-01), Uraneck et al.
patent: 4754008 (1988-06-01), Sid et al.
patent: 5521268 (1996-05-01), Ghyzel et al.

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