JP3104315B2 - Method of manufacturing toner for heat fixing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for developing an electrostatic image formed on the surface of an image carrier by a magnetic brush method, and is used for heat fixing by mixing with a magnetic carrier or constituting a magnetic developer alone. Related to toner,
In particular, the present invention relates to a method for producing a toner for heat fixing, which prevents background fog and has improved offset resistance.

[0002]

2. Description of the Related Art Conventionally, as an image forming means in an electrophotographic method or an electrostatic recording method, a photoconductive substance is generally used, and after forming an electrostatic charge image on a surface of an image carrier by various means, the electrostatic charge image is formed. Is developed using a toner, and if necessary, a toner image is transferred to a transfer material such as paper and fixed by heating or pressure application to obtain a copy. When the electrostatic image is developed, a magnetic brush method is generally used. As a developer used in the developing means by the magnetic brush method, a magnetic carrier and a non-magnetic or weak magnetic toner are used. There are many two-component developers mixed. On the other hand, there is a method of using a one-component developer composed of a resin and magnetic powder as a developer.

[0003] Among the above-mentioned developers, most of those containing a toner which is easily melted by heating have a property of easily aggregating during storage or in a copying machine, and have a drawback that the so-called preservability is reduced. On the other hand, if a resin having a high molecular weight is used as the resin constituting the toner in order to improve the preservability, the fixing temperature rises and more heat is required at the time of fixing, so that the fixing property is lowered. Further, in order to improve the preservability, for example, it is conceivable to add a large amount of a fluidity modifier or the like, but as described above, the fixability deteriorates, so that it is not preferable to include too much.

[0004]

SUMMARY OF THE INVENTION In order to solve the above problems,
In order to achieve both fixability and storage stability, the maximum value of a chromatogram (hereinafter referred to as GPC chromatograph) measured by gel permeation chromatography is as follows:
A toner containing an ethylene-based olefin polymer (for example, polyethylene wax) using a styrene-based copolymer present in each of a low molecular weight region and a high molecular weight region and having a melt viscosity at 140 ° C. of 10 to 10 ⁶ CPS is proposed. (See, for example, U.S. Pat. No. 4,499,168).

However, the above-mentioned resin having a so-called two-peaked peak has a disadvantage that the dispersibility is low due to the mixture of a high-viscosity component and a low-viscosity component. Therefore, when such a resin is used, there is a problem that the background density increases and a so-called fogging phenomenon occurs. In addition, the toner containing the ethylene-based olefin polymer has a low offset resistance in a hot roll fixing method using an oilless type heat roll, and the toner adheres to the hot roll, and this toner is used in the next copy. There is also a problem that an offset phenomenon of being transferred to paper occurs. In any case, the image quality is degraded due to the occurrence of the undesired phenomena as described above, and there is a problem in that it is not possible to meet the demands that have become increasingly strict in recent years.

The present invention solves the above-mentioned problems in the prior art, prevents the background fog, improves the offset resistance, and enables a method of manufacturing a toner for heat fixing capable of forming a high-quality image. The purpose is to provide.

[0007]

In order to achieve the above object, according to the present invention, a chromatogram measured by gel permeation chromatography has a molecular weight of one.
It has a maximum value in the range of 10,000 to 500,000 and a molecular weight of 10,000 to 5
Thousands of ranges styrene having no maximum value - a binder resin comprising an acrylic copolymer, and polypropylene 1 to 5 wt% is that 10,000CPS hereinafter melt viscosity at 160 ° C., colorant, a charge control agent , And a total of 20% by weight or less of optional components such as a flow modifier , and then heated at 180 to 220 ° C.
The styrene-acrylic copolymer is obtained by heat kneading.
The chromatograph in the coalescence has a molecular weight of 100,000 to 50
Maximum value in the range of 10,000 and molecular weight in the range of 10,000 to 50,000
So, it adopted the technical means that.

[0008] In the present invention, the magnetic material fine powder is 20 to
80 wt% is contained in or as a manufacturing method of the magnetic toner. Such a magnetic toner may be used alone or in combination with a magnetic carrier.

In the present invention, it is not preferable that the maximum value of the GPC chromatograph is in a region exceeding a molecular weight of 500,000 because the fixing temperature of the toner becomes high. On the other hand, when the maximum value is in a region having a molecular weight of less than 100,000, the impact resistance and durability of the toner are reduced, which is inconvenient.

By setting the kneading conditions, the maximum value of the GPC chromatograph is configured to be in the range of 10,000 to 50,000 in molecular weight, but if the maximum value is in the region exceeding 50,000 in molecular weight, This is not preferable because the fixing temperature of the toner increases. On the other hand, when the above-mentioned maximum value is in a region having a molecular weight of less than 10,000, the fluidity of the toner is reduced, and the toner is easily aggregated, which is disadvantageous.

Polypropylene has a viscosity of 10,000 CP
If it exceeds S, the dispersibility in the binder resin becomes poor. However, if the viscosity is too low, the effect of preventing offset is reduced. If the addition amount is less than 1% by weight, the intended offset resistance deteriorates, while if it exceeds 5% by weight, the fogging phenomenon deteriorates, which is not preferable.

In the toner of the present invention, various materials such as a colorant and a charge control agent can be used together with the binder resin as required. As the colorant, for example, pigments or dyes such as carbon black, aniline blue, calco oil blue, chrome yellow, quinoline yellow, Dupont oil red, malachite green oxalate, lamp black, rose bengal, and nigrosine dye can be used. As the charge control agent, for example, a fatty acid-modified nigrosine dye, a triphenylmethane dye, a metal-containing azo dye and the like can be used. Further, a magnetic powder such as Fe ₃ O ₄ may be added.

Further, if necessary, inorganic fine powder such as hydrophobic silica, alumina and titanium dioxide, and fine resin powder such as polytetrafluoroethylene and polystyrene may be added to the toner of the present invention.

The amounts of various materials other than the binder resin described above may be determined according to the electrical characteristics required of the toner, but generally 5% by weight in order to secure the fixing property.
It is desirable to make the following.

The toner in the present invention can be produced by a known method such as a pulverization method, but is adjusted to an average particle size of 5 to 15 μm from the viewpoint of image quality. The toner of the present invention is mixed with a magnetic carrier and prepared as a developer. Known magnetic carriers can be used, but from the viewpoint of image quality, magnetite or soft ferrite (Ni-Zn, Mg-Zn, Cu-Zn, Ba-
Carriers containing iron oxides of Ni-Zn type or the like are preferable. The average particle diameter of the magnetic carrier is 30.
It is preferable to adjust so that the saturation magnetization s becomes 50 to 70 emu / g.

In the present invention, the particle size of the toner is a value measured by a Coulter Counter Model TA-II (manufactured by Coulter Electronics Co., Ltd.), and the magnetic characteristics of the magnetic carrier are measured by a vibrating sample magnetometer (VSM-manufactured by Toei Kogyo). III)
Is a value measured with a maximum magnetic field of 10 kOe.

Next, the toner is contained in the toner of the present invention.
As magnetic material fine powder to be used, Fe _ThreeO_Four, Fe
_TwoO_Three, Γ-Fe_TwoO_Three, NMO • Fe_TwoO_Three(However,
M is one of metals such as Ni, Cu, Mn, and Zn, or
Oxidation of two or more, one or two or more of n = 5 to 6)
Iron-based magnetic material fine powder can be used. Above
Among the above materials, in terms of magnetic properties and hue, Fe_ThreeO_FourBut
desirable. The above magnetic material fine powder is uniformly dispersed in the toner.
The average particle size is about 0.1 to 3 μm to be dispersed and contained in
Degree is desirable.

Next, when the magnetic toner is used, if the content of the magnetic material fine powder is less than 20% by weight, the fixing property is improved, but the magnetic force of the toner is reduced. This is inconvenient because it separates from the surface, fouls the image with ground fog, and causes toner scattering. On the other hand, if the content is more than 80% by weight, the attraction force to the surface of the developing roll becomes large, preventing smooth transfer to the image carrier side in the developing area, lowering the developing property, and impairing the fixing property in the later stage. Is not preferred.

[0019]

According to the above construction, the dispersibility is improved even during the kneading step in the production of the toner, and a uniform composition can be obtained. On the other hand, after the kneading, the toner has a so-called two-peak peak molecular weight distribution, and the fixability and preservation are improved. It is possible to balance with sex.

[0020]

Example: 80 parts by weight of styrene-acrylic copolymer (TIZ102 manufactured by Fujikura Kasei) 10 parts by weight of carbon black (# 50 manufactured by Mitsubishi Kasei) 3 parts by weight of polypropylene (Viscol 550P manufactured by Sanyo Chemical Industries, melt viscosity at 160 ° C. 200 CPS) 2 parts by weight of a charge control agent (oil black BY manufactured by Orient Chemical) 5 parts by weight of CaCO ₃ (NS # 2500 manufactured by Nitto Powder Chemical Co., Ltd.) The above components were dry-mixed and kneaded by heating in a kneader at the temperature shown in Table 1. . The resulting mixture was cooled and solidified, and then pulverized by a jet mill into particles of 20 μm or less. Next, the toner was classified through a zigzag classifier to obtain a toner having a volume average particle diameter of 10 μm. 0.5 parts by weight of SiO ₂ (R972 manufactured by Nippon Aerosil) was externally added to this toner, mixed with a Henschel mixer, and adhered to the surface of the toner to obtain a positively charged toner. Next, this toner and ferrite carrier (KBN-100 manufactured by Hitachi Metals, average particle size: 74 to 149 μm)
To prepare a heat-fixing developer having a toner concentration of 3% by weight. A commercially available copying machine (SF7300 manufactured by Sharp Corporation) is used.
Table 1 also shows the results of image evaluations using

[0021]

[Table 1]

The average molecular weight of the binder resin alone before kneading according to GPC chromatography has a single peak at 21.5 × 10 ^4.
By kneading at 0 ° C., it was confirmed that there was a peak also on the low molecular weight side. It was also confirmed that the image quality such as image density and resolution was good, and that the fixing property and the offset resistance were also excellent. This shows that the effect is remarkable when compared with the comparative example described below.

In the composition of the above example, the average molecular weight before kneading was determined to be 22.0 × 10 2 by GPC chromatography.
^{In 4} , a styrene-acrylic copolymer resin having no local maximum value on the low molecular weight side even after kneading was used, and a toner was produced in exactly the same manner at a kneading temperature of 200 ° C. The image with this toner had a density of 1.45, a resolution of 5.6 lines / mm, and was very good without fogging. However, the fixability was only 75% and the offset resistance was 185 to 220 ° C. The offset temperature range was narrow.

Styrene-acrylic copolymer 50 parts by weight (TIZ104 manufactured by Fujikura Kasei) Magnetite 45 parts by weight (EPT500 manufactured by Toda Kogyo) Polypropylene 3 parts by weight (Viscol 330P manufactured by Sanyo Kasei Kogyo, melt viscosity at 160 ° C. 4000 CPS) Charge control 2 parts by weight of the agent (Bontron E81 manufactured by Orient Chemical Co., Ltd.) The above components were dry-mixed and kneaded with a kneader at a temperature shown in Table 2. The resulting mixture was cooled and solidified, and then pulverized by a jet mill into particles of 20 μm or less. Next, this pulverized powder was introduced into a hot air stream at 120 ° C. and heat-treated, and then classified through a zigzag classifier to obtain a magnetic toner having a volume average particle diameter of 10 μm. This magnetic toner is made of SiO
₂ (R972 manufactured by Nippon Aerosil Co., Ltd.) was externally added in an amount of 0.5 part by weight, mixed with a Henschel mixer and attached to the surface of the magnetic toner to obtain a negatively charged magnetic toner. Next, 40 parts by weight of the magnetic toner and a ferrite carrier (manufactured by Hitachi Metals, Ltd.)
60 parts by weight of KBN-100 (average particle size: 74 to 105 μm) to prepare a developer for heat fixing, and the results of evaluation of the developed and fixed images are also shown in Table 2. The developing conditions and fixing conditions are as follows.

That is, a developing device having a SUS304 sleeve having an outer diameter of 31 mm, a cylindrical permanent magnet magnetized octapole symmetrically, and a magnet roll having a magnetic flux density on the sleeve of 650 G is provided. The electrostatic latent image (surface potential -600 to -400 V) on the OPC photosensitive member was reversely developed. The distance between the photoreceptor and the sleeve is 0.4 mm, the toner regulation thickness is 0.35 mm, the sleeve is rotated at 200 rpm in the same direction as the photoreceptor in the developing section, and the permanent magnet is rotated at 900 rpm in the opposite direction to the sleeve. Rotated at pm. The toner image obtained by the development was corona-transferred to plain paper and fixed by a hot roll. The fixing was carried out by using a heating roll whose surface was coated with a PFA resin and a pressure roll made of silicone rubber at a fixing temperature of 180 ° C. and a fixing pressure of 1.0 kg / cm as a linear pressure.

[0026]

[Table 2]

As is clear from Table 2, it was confirmed that the maximum value of the molecular weight distribution had two peaks after kneading and forming the toner (the molecular weight of the resin alone before forming the toner was 14.5 × 10 ^4). Has a single peak at the same time.), Very good results were obtained in terms of image, fixability, and offset resistance.

[0028]

As described above, the present invention has the structure and operation as described above. Therefore, it is possible to prevent the occurrence of ground fog, to achieve both the fixing property and the preservability, and to improve the offset resistance. This has the effect that a high quality image can be formed.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-56-16144 (JP, A) JP-A 1-284863 (JP, A) JP-A-3-63659 (JP, A) JP-A 3- 121460 (JP, A) JP-A-63-179367 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 9/08

Claims (2)

(57) [Claims] 1. A chromatograph measured by gel permeation chromatography has a molecular weight of 100,000 to 5
It has a maximum value in the range of 10,000 and a molecular weight in the range of 10,000 to 50,000
A binder resin comprising a styrene-acrylic copolymer having no maximum value, and a melt viscosity at 160 ° C. of 100,000.
Polypropylene 1 to 5% by weight is 0CPS hereinafter, colorants, charge control agents, the total of optional components such as flow modifiers 20
Wt% or less, and heat-kneaded at 180 to 220 ° C.
By doing so, the styrene-acrylic copolymer
The molecular weight is in the range of 100,000 to 500,000
Method for producing a heat-fixing the toner, characterized in that had to have a maximum value <br/> in the range of molecular weight from 10,000 to 50,000 and. 2. The method for producing a toner for heat fixing according to claim 1, wherein the magnetic material fine powder is contained in an amount of 20 to 80% by weight.