Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1989-06-26
1991-11-19
Bleutge, John C.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
524847, 526318, 5263182, 526346, 526934, C08F26510, C08K 304
Patent
active
050667270
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a resin suitable for use in an electrophotographic toner which is adapted to develop electrophotographic latent images in electrophotography, electrostatic recording, electrostatic printing and the like.
BACKGROUND ART
In electrophotography, the copying speed tends to increase further in recent years to meet the ever increasing quantity of information to be dealt with. On the other hand, it is desired in electrophotography that copied marks have the same quality from the first copy to the several ten thousandth copy.
In order to obtain vivid marks even in high-speed copying, it has conventionally attempted to improve toner resins by placing importance on heat-melting characteristics such as low-temperature fixing property and offsetting resistance as well as the electrification stability of toners.
With a view toward attaining such a goal, the present inventors have already developed a new technique in which a styrene resin having a lower molecular weight (Mn: 1,000-5,000) is used as a toner resin (PCT/JP 87/00819).
However, polyvinyl chloride (PVC) resistance has recently come to the surface as a new problem. When a sheet of paper bearing a price or the like copied thereon by way of example is left over under a load on a PVC sheet for one week, some of the marks copied is caused to transfer to the PVC sheet and for example, one zero (0) disappears from the copied paper sheet. This will certainly causes a serious problem because the price has been reduced by one figure. Further, the PVC sheet has been smeared by the sticky tone deposited thereon, thereby causing another problem.
As a result of a follow-up test, it was found that the above-mentioned technique developed by the present inventors is not fully satisfactory in PVC resistance although it is extremely good in low-temperature fixing property, offsetting resistance, mark vividness and other properties. As possible reasons for this insufficiency, it may be mentioned that since the styrene-base resin has strong absorbing capacity for a plasticizer such as dioctyl phthalate in the PVC sheet, the plasticizer is caused to migrate into the toner and the toner is plasticized as a result.
DISCLOSURE OF THE INVENTION
An object of this invention is to provide a toner resin, which has excellent fixing property and also significantly-improved PVC resistance, by dissolving a low molecular polymer in a monomer, dispersing the resultant mixture in an aqueous system and then polymerizing same.
The above object of this invention has been fulfilled by the provision of a toner resin which comprises as a principal component a polymer obtained by mixing 20-80 parts by weight of a low molecular polymer having a number average molecular weight of 1,000-5,000 and a glass transition temperature (Tg) of 40.degree.-75.degree. C., 80-20 parts by weight of a vinyl monomer, the sum of said low molecular polymer and vinyl monomer being 100 parts by weight, 0.01-5 parts by weight of a polymerization initiator and 0-3 parts by weight of a crosslinking agent, dispersing the resultant mixture in an aqueous system and then polymerizing same.
BEST MODE FOR CARRYING OUT THE INVENTION
The low molecular polymer useful in the practice of this invention may preferably be that produced by feeding a vinyl monomer, a polymerization initiator and a solvent continuously into a system of 190.degree.-230.degree. C. and polymerizing them in a liquid state by solution polymerization. Illustrative examples of the vinyl monomer include acrylic esters such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, octyl acrylate, cyclohexyl acrylate, lauryl acrylate, stearyl acrylate, benzyl acrylate, furfuryl acrylate, tetrahydrofurfuryl acrylate, hydroxyethyl acrylate, hydroxybutyl acrylate, dimethylaminomethyl acrylate and dimethylaminoethyl acrylate; methacrylic esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, octyl methacrylate, lauryl methacrylate, stearyl methacrylate, cyclohexyl methacr
REFERENCES:
patent: 4535049 (1985-08-01), Honda et al.
patent: 4837100 (1989-06-01), Murofushi et al.
Aizawa Hironori
Okubo Atsuo
Shin Masaaki
Bleutge John C.
Jagannathan Vasu S.
Mitsui Toatsu Chemicals Incorporated
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