JPH065392B2 - Electrophotographic toner for heat roller fixing - Google Patents

Description

TECHNICAL FIELD The present invention relates to a heat roller fixing electrophotographic toner.

Conventional technology Conventionally, in a heating roller fixing method that uses a roller formed of a material having excellent releasability for toner such as fluorine resin on the roller surface, if the roller temperature is too high, the molten toner image Moved to the heat roller,
Hot offset development that re-transfers onto the fixed sheet,
When the roller temperature is low, there is a problem that cold offset development, in which a non-melted toner image is transferred again, occurs.

In order to solve these problems, in the heating roller fixing method, how to widen the temperature range from the temperature at which cold offset occurs to the hot offset temperature is a major issue, and various improvements have been attempted for that purpose. Was there.

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

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

3) The binder resin contains a material having good releasability such as low molecular weight polyolefin.

Each method is proposed. However, above 1), 2)
Although the method (1) is effective for hot offset, the lower limit fixing temperature rises, so the appropriate fixing temperature range is not expanded. The method 3) is effective for jam winding, but the offset resistance is not sufficient.

To prevent cold offset, it has been proposed to use a resin that has good adhesiveness to paper, such as polyester or epoxy resin, but this method also does not have sufficient hot offset resistance, and the appropriate temperature range is not maintained. It cannot be expanded.

OBJECT The present invention solves the above problems of the prior art.

According to the present invention, the toner particles contain a vinyl resin and a polyester resin as main components, the vinyl resin forms a continuous phase, and the polyester resin forms a discontinuous phase having a diameter of 0.5 μm or more. This is an electrophotographic toner for fixing on a heat roller.

With the above structure, the toner of the present invention has a low fixing lower limit temperature and a high hot offset temperature.

The vinyl resin used in the present invention includes styrene, o
-Methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2,
4-dimethylstyrene, pn-butylstyrene, p-
tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, p-methoxy styrene, p-phenyl styrene , P
-Styrenes such as chlorostyrene and 3,4-dichlorostyrene, vinylnaphthalene, ethylene, propylene,
Ethylene unsaturated monoolefins such as butylene and isobutylene, vinyl chloride, vinyl bromide, vinyl fluoride, vinyl acetate, vinyl propionate, vinyl benzoate, vinyl esters such as vinyl butyrate, methyl acrylate, ethyl acrylate, N-Butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, α- Methyl chloroacrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, lauryl methacrylate. Α-Methylene aliphatic monocarboxylic acid esters such as 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, acrylonitrile, methacrylonitrile, and acrylamide. Acrylic acid or methacrylic acid derivatives, vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, methyl isopropenyl ketone, N-vinyl pyrrole, N-vinyl Examples include homopolymers, copolymers and terpolymers obtained by polymerizing N-vinyl compounds such as carbazole, N-vinylindole and N-vinylpyrrolidene. .

Among these many vinyl resins, styrene-α-
Vinyl-based resins composed of methylene aliphatic monocarboxylic acid esters are preferable, and the weight average molecular weight measured by the gel permeation method is about 20,000 to 400,000.
Are preferred.

The polyester resin used in the present invention has a softening point of 50 which is synthesized from a diol component and a dicarboxylic acid component.
Refers to saturated or unsaturated polyesters at ~ 150 ° C. Examples of those combinations include fumaric acid / oxypropylene-2,2
-Bis (4hydroxyphenyl) propane, terephthalic acid / polyethylene glycol, maleic anhydride / hydrogenated bisphenol A, phthalic anhydride / polyoxyethylene (2) -2,2 bis (4hydroxyphenyl) propane, etc. .

Since the continuous phase in the toner is a vinyl resin, the ratio of the vinyl resin to the polyester resin of the present invention is 50/50 to 95.
/ 5 is preferable, and more preferably 75/25 to 90/10.
Is the range.

The diameter of the polyester resin particles forming the discontinuous phase is
It is 0.5 μ or more, preferably 0.5 μ to 3 μ. 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 piece. Therefore, the kneading conditions may be adjusted while checking the diameter of the discontinuous layer. As shown in the figure, the cross section of the toner after it has been made into toner shows a continuous phase of vinyl resin.
Discontinuous phase 2 of polyester resin exists in 1 in a dispersed state.

As the colorant used in the present invention, various pigments and dyes are used and are not particularly limited. For example, carbon black, copper phthalocyanine blue, oil black,
Nigrosine dye, ultramarine, navy blue, chrome yellow, rhodamine,
Carmin 6B, quinacridone pigment, benzidine pigment and the like.

The invention of this application will be specifically described below with reference to Examples. The amounts (parts) of the respective components in the examples 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 with fumaric acid and etherified bisphenol A (molecular weight 10,000) 20 parts Carbon black 10 parts The material of the above formulation is heat-kneaded with two roll mills to make polyester The kneading time was determined so that the diameter of the discontinuous phase was 1 μm. The diameter of the discontinuous phase was measured as follows. That is, a small piece of the kneaded material was taken out from two rolls, cooled, and cut with a microtome to obtain a thin piece of about 0.1 μm.

This thin piece was observed with a transmission scanning electron microscope to measure the diameter of the discontinuous layer.

Next, the kneaded product was taken out from the two rolls after kneading, cooled, pulverized, and classified to obtain toner particles having a particle size of 5 to 20 μm. 95 parts of carrier iron powder was mixed with 5 parts of this toner to obtain a developer. Next, after developing an electrostatic latent image formed by a usual electrophotographic method with this developer, the toner image was transferred onto a transfer paper and a fixing test was conducted as follows.

The fixing roller has a surface formed of Teflon (DuPont) (FT4700; manufactured by Ricoh Co., Ltd.). When fixing with this fixing device, the cold offset is 135 °.
It was confirmed that C and hot offset occurred at 220 ° C and the fixing temperature range was wide.

Example 2 Toner composition Styrene-2 ethylhexyl acrylate copolymer (polymerization ratio 85/15, molecular weight 200,000) 70 parts Polyester resin with terephthalic acid and etherified bisphenol A (molecular weight 10000) 30 parts Carbon black 10 parts The above toner composition Other than that, toner was prepared under the same conditions as in Example 1 and tested under the same conditions, and it was found that the cold offset was 130 ° C and the hot offset was 230 ° C, and the fixing temperature range was wide.

Example 3 Toner Composition Styrene-butyl acrylate copolymer (polymerization ratio 70/3
0, molecular weight 300,000) 85 parts Polyester resin with fumaric acid and etherified bisphenol A (molecular weight 15,000) 15 parts Nigrosine dye 2 parts Carbon black 10 parts A toner was prepared under the same conditions as in Example 1 except for the above toner composition and 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 the polyester discontinuous phase was sufficiently dispersed to form a dispersed phase of particles of 0.1 μm or less.
When the obtained toner was tested in the same manner as in Example 1,
The cold offset remained unchanged at 135 ° C, but the hot offset dropped significantly to 170 ° C.

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

[Brief description of drawings]

 The drawing is a schematic view showing a cross section of the toner of the present invention. 1 ... Continuous phase of vinyl resin 2 ... Discontinuous phase of polyester resin

Claims (1)

[Claims] 1. A toner particle 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 μm or more. An electrophotographic toner for fixing on a heat roller.