JPH01133065A - Heat roll fixable toner - Google Patents

Abstract

PURPOSE:To enable fixing at low temperature and low pressure by incorporating a binder resin specified in melt viscosity and a colorant. CONSTITUTION:The heat roll fixable toner contains the binder resin having a melt viscosity of 5X10<5>-1X10<6> poise at 110 deg.C and that of 9X10<4>-3X10<5> poise at 120 deg.C, and the colorant, that is, the binder resin to be used is a thermoplastic resin having a low melt viscosity at low temperature in order to obtain good fixability and a melt viscosity near the conventional ones at high temperature in order to prevent hot offset, thus permitting the obtained toner to be fixed at a fixing temperature and a fixing pressure both lower than the conventional ones, and warming-up time to be remarkably shortened.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a toner for thermal roll fixing that visualizes an electrostatic latent image or a magnetic latent image formed on a two-image carrier, and particularly relates to a The present invention relates to a toner for thermal roll fixing that can be fixed at high temperature and low pressure.

[Conventional technology]

Conventional 3 For example, as an image forming method in an electrophotographic apparatus, 9 a photoreceptor drum is used as an image carrier, and after the surface of the photoreceptor drum is uniformly charged by a corona charging means or the like,
The most common method is to expose the image to light to form an electrostatic charge image on the surface of the photoreceptor drum, visualize it using a developer using a magnetic brush method, etc., transfer it onto a recording material, and then heat and fix it. .

Most of the above-mentioned fixing temperatures require a temperature of 150° C. or higher.

[Problem that the invention seeks to solve]

In recent years, there has been a strong demand for copying machines that are energy efficient and have short warm-up times, and especially in these days when home-use copying machines are desired, it is necessary to use a commercial low-voltage power supply, and the emergence of developers with low fixing temperatures is desired. It is rare. As means for lowering the fixing temperature, there are methods such as lowering the average molecular weight of the binding resin or lowering it by mixing a low molecular weight substance such as wax with the binding resin. However, in this method, blocking may occur and the developer may become lumpy, and after the developer is melted by the heat roll, a portion of the melt remains on the heat roll.

There is a problem in that an offset occurs. Further, conventional toners for hot roll fixing use resins with a wide molecular weight distribution (weight average molecular weight/number average molecular weight) to prevent cold offset and hot offset. That is, in order to prevent offset, a resin having a high melt viscosity at low temperatures and a low melt viscosity at high temperatures is used. Therefore, in order to obtain good fixing properties, it is necessary to maintain a temperature of 140 to 190°C, and to maintain a temperature of 1 kg between a pair of fixing rolls.
It is necessary to apply a pressure of about / cm. - It is advantageous to lower the fixing temperature from the viewpoint of power consumption and to fix at a low pressure to prevent paper wrinkles etc. during fixing, but conventional toners cannot satisfy these points. The problem is that it cannot be done.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems existing in the above-mentioned prior art and to provide a toner for hot roll fixing that can be fixed at low temperature and low pressure.

[Means for solving problems]

As a result of intensive research to solve the problems existing in the above-mentioned prior art, the present inventors found that compared to conventional bonding resins, the melt viscosity at high temperatures is close to that, but the melt viscosity at low temperatures is The present inventors have discovered that good fixing can be achieved at low temperature and pressure by using a binding resin with a significantly lower temperature than the above range, and have come up with the present invention.

That is, the toner for thermal roll fixing of the present invention is as follows.

The melt viscosity at 110°C is in the range of 5 x 104 to 1 x 106 voids, and the melt viscosity at 120°C is 9 x
It is characterized by containing a binding resin in the range of 104 to 3X105 poise and one colorant.

When fixing a toner image using a hot roll, a primary thermoplastic resin is used as the binding resin. for example,
Styrenes, vinyl esters.

Esters of α-methylene aliphatic monocarboxylic acids.

Acrylonitrile, methacrylonitrile, acrylamide, vinyl ethers, vinyl ketones.

A homopolymer obtained by polymerizing monomers such as an N-vinyl compound, a copolymer obtained by copolymerizing a combination of two or more of these monomers, or a mixture thereof is used.

Also used are non-vinyl thermoplastic resins such as epoxy resins and polyester resins, or mixed resins with vinyl resins such as those described above.

However, as mentioned above, conventionally, among such resins, those having a high melt viscosity at low temperatures and a low melt viscosity at high temperatures have been used.

Good fixing at low temperature and low pressure was insufficient. On the other hand, in the present invention, in order to obtain good fixing properties when hot roll fixing is performed at low temperature and low pressure, the present invention has a low melt viscosity at low temperatures and a method for preventing hot offset. .

At high temperatures, a thermoplastic resin with a melt viscosity close to that of conventional resins is used. Specifically, the melt viscosity at 110°C is 5×1
The range is 04 to 1X106 poise and 5.

The melt viscosity at 120° C. is in the range of 9×10 4 to 3×10 5 poise. This is because if the melt viscosity at 110° C. is smaller than 5×10 5 , cold offset tends to occur, while if it is larger than 1×10 6 poise, the fixing performance at low temperature and low pressure decreases. Also 12
If the melt viscosity at 0° C. is smaller than 9×10 4 poise, hot offset is likely to occur, and if it is larger than 3×10 5 poise, fixing performance is reduced. The melt viscosity of the resin can be adjusted by introducing a crosslinking reaction during the polymerization process to partially crosslink the resin, for example in the case of a styrene-acrylic copolymer.

In the present invention, among thermoplastic resins having such a melt viscosity, it is preferable to use styrene resins. From the viewpoint of preventing offset, among these styrene resins, those containing 25% or more of styrene components are desirable. In the case of hot roll fixing, styrene-acrylic copolymers or styrene-butadiene copolymers are often used as the styrene resin. Styrene-butadiene copolymers have a high offset prevention effect.

Since pulverization is difficult and productivity is low, it is preferable to use a styrene-acrylic copolymer when producing toner by a pulverization method. In the case of using a styrene-acrylic copolymer in the present invention, the weight average molecular weight (Mw) is 16.5% from the viewpoint of the above-mentioned melt viscosity, fixability and storage stability. OX 10'~19.5
×104, and the number average molecule it (Mn) is 1.3×105
~1.6×104 is desirable. Mw, Mn
If it is smaller than the above range, the storage stability will be reduced, and if it is larger than the above range, the fixing property will be reduced. Styrene like this
When using an acrylic copolymer, it is desirable to contain a mold release agent, typically an aliphatic resin, in an amount of 1 to 10% by weight in order to prevent offset. Preferred mold release agents include polyolefins (polyethylene, polypropylene, etc.) having a weight average molecular weight of 1X10' or less. Note that the molecular weight is a value measured by GPC method (gel permeation chromatography).

In addition to the above resin, the toner of the present invention contains known colorants such as carbon black, chrome yellow, rose bengal, phthalocyanine blue, and aniline black as essential components. Furthermore, known toner additives such as charge control agents such as nigrosine dyes, triphenylmethane dyes, and metal-containing ab dyes, and fluidity modifiers typified by hydrophobic silica may also be contained.

〔Example〕

Styrene acrylic copolymer 86 parts by weight (Mw
=18.6×1041104l, 5×104) Carbon black 10 parts by weight (manufactured by Mitsubishi Chemical
#44) Charge control agent 2 parts by weight (Bontron E81 manufactured by Orient Chemical) Low molecular weight polypropylene 2-layer II (Viscol 55 manufactured by Sanyo Chemical Co., Ltd.)
0 P) Preliminarily mix the raw materials in the above formulation using a ball mill.

After heating and melting and kneading with a kneader, it is cooled and solidified, crushed with a shared door, mill, etc., and then classified into two to obtain an average particle size of 12 μm.
created toner. For comparison, styrene acrylic copolymer Mw=27.0×104, Mn=
A toner was prepared in the same manner as above using 3.3×10 4 resin.

Table 1 shows the main physical properties of both styrene-acrylic copolymers, which are the above-mentioned binding resins, and Figure 9 also shows the relationship between viscosity and temperature.

Margin below The melt index in the table is 150°C.

The straight lines A and B in Figure 2 correspond to the above-mentioned Example and Comparative Example, respectively. In this case, the viscosity was measured using a commercially available flow tester (CFT-500 manufactured by Konsei Seisakusho) under conditions of a plunger area of LED, a die diameter of 11 cm, and a load of 20 kg.

As is clear from the figure, the binding resin of this example is 110~
Even at a low temperature of 125° C., the melt viscosity is lower than that of the binder resin of the comparative example, and the fixing properties tend to be good.

Next, a developer was prepared by mixing each toner of the above Examples and Comparative Examples with a ferrite carrier (Hitachi Metals KBN-100) so that the toner concentration was 4% by weight. A copying test was conducted using UBiX3000 (manufactured by Rokusha). Both developers.

A good image with a density of 1.3 was formed, and the fixing properties and anti-offset properties were also good. However, when the toner according to the comparative example was used, a fixing temperature of 160° C. and a fixing pressure of 1 kg/cm were required. On the other hand, when the toner of this example is used, the fixing temperature is 140°C.
It was confirmed that good fixing could be performed at a fixing pressure of 0.5 kg/cm.

In this embodiment, the case of a two-component developer which is a mixture of non-magnetic toner and carrier was described.
The same effect as described above can be expected when using a one-component developer containing F6i powder, or a mixture of the one-component developer and a carrier. Not only electrostatic latent images.

For example, a visualization of a magnetic latent image formed on a magnetic drum.

It can also be used for fixation.

〔Effect of the invention〕

Since the present invention has the structure and operation as described above, it has the effect of being able to fix at a lower fixing temperature and lower pressure than conventional toners. Therefore, it not only saves power but also significantly shortens the warming amplifier time, greatly contributing to improving office efficiency.

[Brief explanation of the drawing]

The figure is a diagram showing the relationship between the viscosity of the binding resin and the temperature.

Claims (3)

[Claims] (1) Melt viscosity is 5×10^5 to 1× at 110℃
10^6 poise, 9x10^4-3x at 120℃
A toner for hot roll fixing, characterized in that it contains a binder resin of 10^5 and a colorant. (2) The weight average molecular weight Mw of the binding resin is 16.0×
10^4 to 19.5 x 10^4, number average molecular weight Mn is 1
．． The toner for hot roll fixing according to claim 1, which uses a styrene-acrylic copolymer having a molecular weight of 3 x 10^4 to 1.6 x 10^4. (3) Claim 2 in which the toner contains 1 to 10% by weight of a releasing resin with a weight average molecular weight of 10,000 or less.
Toner for heat roll fixing as described in section.