Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
2000-03-24
2001-04-03
Martin, Roland (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
C430S109500, C430S111400
Reexamination Certificate
active
06210852
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a toner for heat roller fixing type electrostatically charged image development.
More specifically, the present invention relates to a toner in a developer which is excellent in fixability, anti-spent toner effect and transparency and can form a sharp image when fixing a dry magnetic one-component, dry nonmagnetic one-component, dry two-component, a dry polymerized, liquid dried or liquid toner developer on a copying medium such as paper or a film, which can secure quite a broad temperature range in which a so-called offset phenomenon does not occur (hereinafter referred to as an offset-free temperature range), which is excellent in high-speed fixability and which is satisfactorily put to practical use.
Further, the present invention relates to the toner which can find wide acceptance in copiers, printers, facsimile machines, color copiers, color laser copiers, color laser printers and high speed electrophotographic printers.
BACKGROUND OF THE INVENTION
With the background of the rapid spread of office automation, high-quality or sharp, light-transmissive, well-fixed copied images have been in higher demand than before in electrostatically charged image developing copiers and printers.
One of requirements for such high-quality images is prevention of an offset phenomenon that a toner is not completely fixed on a copying medium such as paper or a film and a part thereof remains on a heat roller and is fixed on a next copying medium to stain the same.
A heat (fixing) roller of a copier is usually heated at 160 to 180° C. in operation. Accordingly, a toner is designed in order to be fixed (bound) at 120 to 190° C. by providing an extra width. The offset phenomenon occurs when a temperature is too high or too low. Thus, for preventing the offset phenomenon and improving the fixability and the sharpness, it is important to secure a toner fixing temperature range which does not cause the offset phenomenon, namely, the offset-free temperature range as broad as possible within said range of 120 to 190° C.
Under these circumstances, the present inventors tried to improve the fixability by selecting a high-viscosity olefin polymer having a cyclic structure as a binder resin for a toner, and further proposed that waxes having a melting point of 60 to 170° C. are added for preventing the offset phenomenon (refer to JP-A-101631/97) . However, the offset-free temperature range so far realized could not reach to the level to be altogether satisfactory enough.
Moreover, the inventors proposed in International Patent publication No. WO 98/29783 specification that the high-viscosity olefin polymer having a cyclic structure is selected as a binder resin for a toner for prevention of the offset phenomenon and a wax selected from amide wax, carnauba wax, higher fatty acids and their esters, higher fatty acid metallic soaps, partially saponified higher fatty acid esters, higher fatty alcohols, polyolefin waxes and paraffin waxes is used. The offset-free temperature range was in the range of 30 to 40° C., and the binder resin could be put to practical use. However, a satisfactory offset-free temperature range being applicable when a binder resin is an olefin polymer having a cyclic structure and a combination of different molecular weights or is made of plural different polymers has not been obtained.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a toner for a dry two-component, dry magnetic one-component, dry nonmagnetic one-component, dry polymerized, liquid dried or liquid toner developer which can more broaden an offset-free temperature range achieved by the invention described in said International Patent Publication No. WO 98/29783 Specification to secure a broad offset-free temperature range being applicable and well suitable for practical use when a binder resin is an olefin polymer having a cyclic structure and a combination of various molecular w eights or is composed of various polymers and which can attain a satisfactory fixability even in the high-speed copying to provide higher-quality or well-fixed, highly light-transmissive, quite sharp copied images of electrostatically charged image developing copiers and printers.
The foregoing object is attained by a toner for development of an electrostatically charged image comprising a binder resin, a function imparting agent, a colorant and a charge control agent, in which the binder resin contains an olefin polymer having a cyclic structure, a combination of two or more waxes having different melting points in the range of 80 to 140° C. is used as the function imparting agent, preferably the difference in the melting point between the wax having the highest melting point and the wax having the lowest melting point is 10 to 40° C. in the combination of two or more waxes, preferably a wax having a polar group and a wax having a nonpolar group are used in the combination of two or more waxes, and preferably the function imparting agent is one of the following combinations (a) to (c) of waxes,
(a) a combination of fatty acid amide wax, oxidized polyethylene wax and polyethylene wax,
(b) a combination of fatty acid amide wax, oxidized polyethylene wax, polyethylene wax and acid-modified polypropylene wax, and
(c) a combination of fatty acid amide wax and acid-modified polypropylene wax.
Further, preferably the olefin polymer having a cyclic structure is composed of a polymer or a polymer fraction having a number average molecular weight of 7,500 or more and a polymer or a polymer fraction having a number average molecular weight of less than 7,500, and in the olefin polymer having a cyclic structure, the content of a polymer or a polymer fraction having a number average molecular weight of 7,500 or more, a weight average molecular weight of 15,000 or more and an intrinsic viscosity (i.v.) of 0.25 dl/g or more is less than 50% by weight based on the entire binder resin, whereby a toner superior in the offset prevention property and the fixability can be provided.
DETAILED DESCRIPTION OF THE INVENTION
The invention is described in detail below.
[I] Components of a Toner
(1) Binder Resin
A binder resin is used to fix a toner onto a copying medium such as paper or a film, and it contains an olefin polymer having a cyclic structure as a main component.
A) Olefin Polymer Having a Cyclic Structure
The olefin polymer is a copolymer of an &agr;-olefin (broadly an acyclic olefin) such as a lower alkene having 2 to 12 carbon atoms, preferably 2 to 6 carbon atoms, for example, ethylene, propylene or butylene, and a cyclic and/or polycyclic compound (cycloolefin) having at least one double bond and 3 to 17 carbon atoms, preferably 5 to 12 carbon atoms, such as norbornene, tetracyclododecene, dicyclopentadiene or cyclohexene, especially preferably norbornene or tetracyclododecene, and it is colorless and transparent, and has a high light-transmission.
This olefin polymer having a cyclic structure is a polymer obtained by, for example, a polymerization method using a metallocene catalyst or a Ziegler catalyst and a catalyst for metathesis polymerization, namely double-bond-opening and ring-opening polymerization reactions.
Examples of synthesis of the olefin polymer having a cyclic structure are disclosed in JP-A-339327/93, JP-A-9223/93, JP-A-271628/94, EP-A-203799, EP-A-407870, EP-A-283164, EP-A-156464, and JP-A-253315/95.
According to these examples, the olefin polymer is obtained by polymerizing at least one of the cycloolefin monomers optionally with at least one of the cycloolefin monomers at a temperature of −78 to 150° C., preferably 20 to 80° C. and a pressure of 0.01 to 64 bars in the presence of a catalyst comprising at least one metallocene containing zirconium or hafnium together with a cocatalyst such as aluminoxane. Other useful polymers are described in EP-A-317262, and hydrogenated polymers and copolymers of styrene and dicyclopentadiene are also available.
The metallocene catalyst is activated when dissolved in an inert hydrocarbon such as an al
Frommer & Lawrence & Haug LLP
Martin Roland
Ticona GmbH
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