JPS60260062A - Electrophotographic toner for heat roller fixing - Google Patents

Abstract

PURPOSE:To improve offset resistance by consisting essentially toner particles of a vinyl resin and polyester resin in which the vinyl resin forms a continuous phase and the polyester resin forms a discontinuous phase of a specific diameter or above. CONSTITUTION:The toner particles consist essentially of the vinyl resin and polyester resin in which the vinyl resin forms the continuous phase and the polyester resin forms the discontinuous phase of >=0.5mu diameter. The vinyl resin to be used is the vinyl resin constituted of styrene alpha-methylene aliphat. monocarboxylate and the weight average mol.wt. thereof is preferably about 20,000- 400,000. The polyester resin to be used refers to the satd. or unsatd. polyester which is synthesized from a diol component and dicarboxylic acid component and has 50-150 deg.C softening point. The lower limit of the fixing temp. is thus made low and the upper limit high and therefore the region of the adequate fixing temp. is expanded and the offset resistance is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD This invention relates to an electrophotographic toner for heated roller servings.

Help i1 Conventionally, in heated roller fixing systems that use rollers whose surfaces are made of a material with excellent toner release properties, such as fluororesin, if the roller temperature is too high, the molten toner may Problems include a hot offset phenomenon in which the image is transferred to the heated roller and then transferred again onto the fixing sheet, and a cold offset phenomenon in which the non-melted toner image is transferred again when the roller temperature is low. .

In order to solve these problems, a major challenge in the heated roller fixing method is how to widen the temperature range from the temperature at which cold offset occurs to the hot offset temperature, and various improvements have been attempted to this end. was.

To prevent hot offset, 1) Expanding the molecular weight distribution of the binder resin.

2) Partially crosslinking the binder resin to increase the cohesive force of the toner.

3) A material with good mold releasability, such as a low molecular weight polyolefin, is included in the binder resin.

Various methods have been proposed. However, above 1), 2)
Although the above method is effective against hot offset, the lower limit fixing temperature increases, so the appropriate fixing temperature range is not expanded. Furthermore, although method 3) is effective against jamming, the offset resistance is not sufficient.

To prevent cold offset, it has been proposed to use resins with good adhesion to paper, such as polyester or epoxy resin, but even with this method, the hot offset resistance is insufficient and it is difficult to maintain the appropriate temperature range. Cannot be expanded.

Purpose This invention solves the above-mentioned problems of the prior art.

Structure This invention provides toner particles containing a vinyl resin and a polyester resin as main components, the vinyl resin forming a continuous phase, and the polyester resin forming a discontinuous phase having a diameter of 0.5 μ or more. This is an electrophotographic toner for thermal roller fixing.

With the above configuration, the toner of the present invention has a low minimum fixing temperature and a high hot offset density.

The vinyl resin used in this invention includes styrene, 0
-Methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2
, 4-dimethylstyrene, p-n-butylstyrene, p
-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene, 1-n-dodecylstyrene, p-methoxystyrene, p-phenyl styrene, p
- Styrenes such as chlorostyrene and 3,4-dichlorostyrene, vinylnaphthalenes, ethylenically unsaturated monoolefins such as ethylene, propylene, butylene and isobutylene, vinyl chloride, vinyl bromide, vinyl fluoride, vinyl acetate, Vinyl esters such as vinyl propionate, vinyl benzoate, vinyl butyrate, methyl acrylate,
Ethyl acrylate, loobyl acrylate, isobutyl acrylate, propyl acrylate, acrylic 1lJn-
octyl, dodecyl acrylate, lauryl acrylate,
Acrylic M2-■Derhexyl, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate,
α-methyl chloroacrylate, methyl methacrylate,
Ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate,
α- such as n-octyl methacrylate, dodecyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylamine ethyl methacrylate, etc. Methylene aliphatic monocarboxylic acid esters, acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide, vinyl ethers 1 such as vinyl methyl ether, vinyl ethyl ether, and vinyl isobutyl ether, vinyl methyl ketone, vinyl hexyl ketone, Homopolymers, copolymers, terpolymers, etc. obtained by polymerizing vinyl ketones such as methyl isopropenyl ketone, N-vinyl compounds such as N-vinylpyrrole, N-vinylcarbazole, N-vinylindole, and N-t'ylpyrrolidene, etc. be.

Among these many vinyl resins, vinyl resins composed of styrene α-methylene aliphatic monocarboxylic acid esters are preferred, and have a weight average molecular weight of about 20,000 to 20,000 as measured by gel permeation method. 40
0,000 is preferred.

In addition, the polyester resin used in this invention is synthesized from a diol component and a dicarboxylic acid component and has a softening point of 5.
It refers to saturated or unsaturated polyesters with a temperature of 0 to 150°C. Examples of such combinations include fumaric acid/oxypropylene-
2,2-bis(4hydroxyphenyl)propane, terephthalic acid/polyethylene glycol, maleic anhydride/
Hydrogenated bisphenol A1 phthalic anhydride/polyoxyethylene (2)-2,2bis(4hydroxyphenyl)
There are propane, etc.

In order to make the continuous phase in the toner a vinyl resin, the ratio of the vinyl resin to the polynisder resin of the present invention is 50/5.
The range is preferably 0 to 9515, more preferably 75/
It ranges from 25 to 90/10.

Further, the diameter of the polyester resin particles constituting the discontinuous phase is 0.5μ or more, preferably 0.5μ to 3μ. The diameter of the discontinuous phase can be achieved by weak dispersion, but the diameter is measured by cutting the kneaded material with a microtome and taking a transmission micrograph of a thin section. Therefore, the crosstalk conditions may be adjusted while checking the diameter of the discontinuous layer.

A schematic diagram of a cross section of the toner after it has been made into a toner shows that a discontinuous phase 2 of polyester resin exists in a dispersed state in a continuous phase 1 of vinyl resin.

Various pigments and dyes can be used as the colorant used in this invention, and there are no particular limitations. For example, carbon black, copper phthalocyanine blue, oil black,
Nigrosine dye, ultramarine, navy blue, chrome yellow, rhodamine,
Carmino 63. Examples include quinacridone pigments and benzidine pigments.

The invention of this application will be specifically explained below with reference to Examples. Note that the amounts (parts) of each component in the formulation are parts by weight.

Example 1 Toner composition Styrene-n-butyl methacrylate copolymer (polymerization ratio 8/2, molecular weight 80,000) 80 parts Polyester resin made from fumaric acid and etherified bisphenol A (molecular weight 10,000) 20 parts Carbon black 10 The materials with the above formulation were heat-kneaded in a two-roll mill, and the mixing time was determined so that the diameter of the polyester discontinuous phase in the cross section of the toner was 1 μm.

The diameter of the discontinuous phase was measured as follows. That is, a small piece of the crosstalk was taken out from two rolls, cooled, and then cut with a microtome to obtain a thin piece of about 0.1 μm.

This thin section was observed with a transmission scanning electron microscope, and the diameter of the discontinuous layer was measured.

Next, the mixed material was taken out from the two rolls after being mixed, cooled, crushed, and classified to obtain toner particles having a particle size of 5 to 20 .mu.m.

Mixing 95 parts of carrier iron powder with 5 parts of this toner,
It was used as a developer.

Next, an electrostatic latent image formed by a conventional electrophotographic method was developed using this developer, and then the toner image was transferred onto a transfer paper and a fixing test was conducted as follows.

The surface of the fixing roller was made of Tebron (Dupont) (FT4γ00: ■, Ricoh @). When I performed fusing with this fuser, the cold offset was 1.
It was confirmed that the fixing temperature range was wide, with hot offset occurring at 35°C and 220°C.

Example 2 Toner composition Styrene-2-ethylhexyl acrylate copolymer (polymerization ratio 85/15, molecular weight 200,000) 70 parts Polyester resin made of terephthalic acid and etherified bisphenol A (molecular weight 10,000) 30 parts Carbon black 10 parts A toner was prepared under the same conditions as in Example 1 except for the above toner composition, and tested under the same conditions. It was found that the fixing temperature range was wide, with a cold offset of 130°C and a hot offset of 230°C.

Example 3 Toner composition Styrene-butyl acrylate copolymer (polymerization ratio 70/
A toner was prepared under the same conditions as Example 1 except for the above toner composition. When tested under the same conditions, the cold offset was 135°C and the hot offset was 240°C.

Comparative Example 1 The composition was the same as in Example 1, but sufficient dispersion was performed to transform the polyester discontinuous phase into a dispersed phase of particles of 0.1 μm or less. When the obtained toner was subjected to the same test as in Example 1, the cold offset remained unchanged at 135°C.
The hot offset was greatly reduced to 110°C.

Effects As explained above, according to the present invention, since the lower limit of the toner fixing temperature is low and the upper limit is high, the appropriate fixing temperature range is expanded and offset resistance is improved.

[Brief explanation of drawings]

The drawing is a schematic diagram without showing a cross section of the toner of the present invention. 1...Continuous phase of vinyl resin 2...Discontinuous phase of polyester resin Patent applicant Rico Co., Ltd. Agent Patent Attorney Hidetake Komatsu Agent Patent Attorney Hiroshi Asahi

Claims (1)

[Claims] The toner particles contain a vinyl resin and a polyester resin as main components, the vinyl resin forming a continuous phase,
An electrophotographic toner for thermal roller fixing, characterized in that a polyester resin forms a discontinuous phase with a diameter of 0.5 μm or more.