JPH0736218A - Heating roller fixing type toner for electrostatic image development - Google Patents

Abstract

(57) [Summary] [Structure] A heating roller fixing type electrostatic image developing toner to which a polyethylene wax having a melting point peak temperature of DSC of 70 to 120 ° C., in which components having a melting point of 50 ° C. or less are removed, is added. This toner can be applied to both a one-component developer and a two-component developer. The polyethylene wax preferably has a number average molecular weight of 300 to 2000, a weight average molecular weight of 300 to 4000, and a melt viscosity at 130 ° C. of 4 to 350 centipoise. [Effect] The fixing temperature of the toner is lowered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat roller fixing type electrostatic image developing toner, and more specifically, to prevent offset and fixability when fixing a toner in a one-component or two-component dry developer at a low temperature. And a toner excellent in hiding power.

[0002]

2. Description of the Related Art The demand for power saving and miniaturization in addition to higher copying speed in heating roller fixing type electrostatic charge image developing type copying machines and printers is increasing due to the spread of office automation in recent years. It's starting. One of the factors for increasing the copying speed in the heating roller fixing type electrostatic image developing type copying machine and printer is mainly the step of fixing the toner image transferred to the plain paper or the like. That is, in a heating roller fixing type electrostatic charge image developing type copying machine and printer, after toner is supplied to the electrostatic charge image on the latent image carrier to obtain a visible image (toner image), the toner image is transferred to a plain paper. Etc., and this is fixed. Here, the fixing of the toner image is generally performed by heat, pressure, or both, but in recent years, a device using a combined heat and pressure method for fixing the toner has become dominant in the market. However, under the present circumstances, since a colorant, a high melting point binder resin, and a high melting point wax are often used as toner components, the fixing temperature of the toner is 150 to 1 on copying paper (plain paper, etc.).
The temperature is as high as 80 ° C, and accompanying this, it is inevitable that the equipment will become larger and consume more power.

[0003]

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to fix a heating roller fixing type electrostatic image developing type copying machine and a printer for downsizing, power saving and speeding up of copying speed. The present invention provides a toner for a one-component type or two-component type developer which is excellent in the prevention of offset, the improvement in fixing property and the hiding power in addition to the reduction of the temperature.

[0004]

The heating roller fixing type electrostatic image developing toner of the present invention contains a colorant and a binder resin as main components, and a portion having a melting point of 50 ° C. or lower is substantially removed. Further, it is characterized by containing a polyethylene wax having a melting point peak temperature of DSC (Differential Scanning Calorimeter) in the range of 70 to 120 ° C. The "polyethylene wax" used here is produced by separating a portion having a predetermined DSC melting point peak temperature by distillation from low molecular weight polyethylene produced by a known method. At this time, a material which does not substantially include a portion having a melting point of 50 ° C. or lower is collected. In addition, the fact that a portion having a melting point of 50 ° C. or lower is not substantially included means that the component is 2% of the whole wax.
It means less than or equal to wt%. Here, the melting point is a value measured by DSC.

In order to solve the above problems, the present inventors considered as one solution to use an additive having a low melting point for the binder resin. Such substances include paraffin wax, higher fatty acid ester wax, for example, montan wax, vegetable natural wax, animal fat wax. However, as a result of further detailed study by the present inventors, the paraffin wax has an adverse effect on the fixability, the storage stability of the toner, the effect of preventing offset, and the fixability when the higher fatty acid ester wax is used, Although the offset prevention effect is obtained to some extent, it has been found that the storage stability of the toner is affected.

By the way, polyethylene waxes having a wide range of melting points are known, but at present, those having a melting point peak temperature of DSC of about 120 to 155 ° C. are added to the toner. In this case, a satisfactory result cannot be obtained unless the fixing temperature of the toner is 150 ° C. or higher on the copy paper. When a polyethylene wax having a melting point of 120 ° C. or lower is added to the toner, like the low melting wax described above,
The toner causes blocking in a short period of time and cannot be used.

The inventors of the present invention have studied from various angles in order to ameliorate this drawback. As a result, the DSC melting point peak temperature of polyethylene wax from 70 to 120 ° C.
By using the one in which the melting point component of 0 ° C. or lower is removed, the above-mentioned defects are improved, the offset prevention effect, the fixability,
It was confirmed that a toner excellent in hiding power could be manufactured.
The present invention has been completed based on these findings.

The polyethylene wax used in the present invention has a number average molecular weight (Mn) of 300 to 2000, preferably 500 to 1500, and a weight average molecular weight (Mw) of 300 to 4.
The melting point peak temperature of DSC is 70 to 120 ° C., preferably 85 to 118.
It is desirable that the melt viscosity at 40 ° C., further at 130 ° C., is 4 to 350 centipoise, preferably 4 to 100 centipoise.

The toner to which the polyethylene wax satisfying these characteristics is added has a low viscosity, a high melting temperature and a fast solidification rate, is excellent in all of the anti-offset effect, the fixability and the hiding power, and is blocked during storage. It has no phenomenon and is excellent in storage stability. In the present invention, the melting point peak temperature of the polyethylene wax measured by DSC is as low as 70 to 120 ° C., so that the copying speed can be increased and the fixing temperature can be decreased.
With respect to the offset prevention effect, an improvement was observed particularly in a low temperature portion as compared with a conventional polyethylene or polypropylene wax having a high melting point, that is, a melting point higher than 120 ° C. Regarding the fixing property, the temperature of the heating roller is 170 to
When the temperature was set to 200 ° C. and the copying speed was 100 sheets / minute, the lower the temperature of the heating roller, the higher the fixability as compared with the high melting point polyolefin wax. Next, when the heating roller was set at 120 to 150 ° C. and the copying speed was operated at 10 sheets / minute, the fixability was dramatically improved. Regarding the storage stability of the toner, although the polyethylene wax in the present invention has a low melting point, the toner to which the polyethylene wax was added did not show a great difference compared with the toner to which the high melting point polyolefin wax was added. . Regarding the hiding power of the toner, the toner of the present invention to which the polyethylene wax was added showed an improvement in the hiding power at the same usage amount as compared with the toner of the high melting point polyolefin wax. At the same time, the gloss was improved. In order to further lower the fixing temperature of the toner, a low melting point binder resin may be combined with the low melting point polyethylene wax according to the present invention.

In view of the above, the polyethylene wax having a melting point peak temperature of DSC from which components having a melting point of 50 ° C. or lower in the present invention is 70 to 120 ° C. is a heating roller fixing type electrostatic image developing type copying machine or It can be concluded that it is effective as an additive to be used in toners that can meet the demands for higher speed and lower temperature fixing in printers in the future.

Examples of the binder resin used in the present invention include those known in this field such as styrene-acrylic copolymers, polyesters and epoxy resins. Examples of the colorant include carbon black. In addition, various cyan, magenta, and yellow dyes and pigments can be used. In addition, colloidal silica (for external addition and internal addition), a charge control material and the like may be used as a toner component, if necessary. The toner of the present invention can be used as a one-component developer or a two-component developer toner. Further, the toner of the present invention can be mixed with magnetic powder to be used as a one-component magnetic toner, or can be used as a full-color toner.

Regarding the addition of low molecular weight polyethylene wax to the toner, Japanese Patent Publication No. 57-52574 and Japanese Patent Publication No. 63-32 are disclosed.
It is also proposed in Japanese Patent No. 180. That is, in the above, the low-molecular-weight polyethylene has a weight-average molecular weight of about 100.
It is said that polyethylene having a weight average molecular weight of about 1000 to 5000 can be effectively used. In addition, these low molecular weight polyethylenes are said to be effective if they have a softening point of 90 to 180 ° C, especially a softening point of 100 to 150 ° C. In the above description, an ethylene-based olefin polymer having a melt viscosity at 140 ° C. of 10 to 10 ⁶ CPS, preferably 10 ² to 10 ⁵ CPS, is 0.1 to 5% by weight of a low molecular weight polyethylene similar to the present invention based on the weight of the developing powder. It is contained. However, these documents and references do not remove low-melting point components having a melting point of about 50 ° C. or lower. Therefore, in any case, those having a low melting point, particularly those having a melting point of 120 ° C. or lower, have low storage stability due to the low melting point component. Expected to be compromised.

[0013]

EXAMPLES The present invention will be described more specifically with reference to Examples and Comparative Examples. (Toner Preparation Method) As a binder resin, MC-10 manufactured by Nippon Carbide Industries Co., Ltd. is used for a styrene-acrylic copolymer.
0, polyester resin Kao Tuffton NE21
55 was used. Binder resin 80% by weight, carbon black (Cabot, Raven 150) 10% by weight, charge control agent (Hoechst Copy Blue PR) 2% by weight, colloidal silica (Fuji Monte Edison # 150) 4
% Of wax and 4% by weight of wax are mixed and melted and kneaded by a two-roll at 130 ° C., cooled and solidified, coarsely crushed, finely classified by a jet mill, and then adjusted to an average particle size of about 10 μm. To create toner.

Example 1 Styrene-acrylic copolymer was used as the binder resin, and HC-A was used as the wax in the above preparation method.

Example 2 Styrene-acrylic copolymer was used as the binder resin, and HC-B was used as the wax in the above preparation method.

Example 3 Styrene-acrylic copolymer was used as the binder resin, and HC-C was used as the wax in the above preparation method.

Example 4 Styrene-acrylic copolymer was used as the binder resin and HC-D was used as the wax in the above preparation method.

Example 5 Styrene-acrylic copolymer was used as the binder resin, and HC-E was used as the wax in the above preparation method.

Example 6 Styrene-acrylic copolymer was used as the binder resin, and HC-C was used as the wax in the above preparation method.

The wax used in Examples 1 to 6 is a low molecular weight polyethylene obtained by polymerizing ethylene by a low pressure method using a Ziegler-Natta catalyst, and a portion having a predetermined melting point is fractionated by a distillation method. At the same time, the portion having a DSC melting point of 50 ° C. or lower was also removed. The physical properties of this product are shown in Table 1.

[0021]

[Table 1] (Note) All numerical values are spot measurement values and do not cover all grades.

Comparative Example 1 Styrene-acrylic copolymer was used as the binder resin, and Hoechst wax PE-190 manufactured by Hoechst Co. was used as the wax in the above toner preparation method.

Comparative Example 2 A styrene-acrylic copolymer was used as the binder resin, and Hoechst wax PE-130 manufactured by Hoechst Co. was used as the wax in the above toner preparation method.

Comparative Example 3 Styrene-acrylic copolymer was used as the binder resin, and polypropylene wax was used as the wax (Viscole 550P,
Sanyo Kasei Kogyo) was used in the above toner preparation method.

Comparative Example 4 Styrene-acrylic copolymer was used as the binder resin, and polypropylene wax was used as the wax (Viscole 660P,
Sanyo Kasei Kogyo) was used in the above toner preparation method.

Comparative Example 5 A polyester resin was used as a binder resin, and a polypropylene wax (Viscole 660P, manufactured by Sanyo Chemical Industry) was used as a wax in the above toner preparation method.

2 parts by weight of these toners and iron powder carrier 9
The mixture was mixed with 8 parts by weight and put in a commercially available electrophotographic copying machine (manufactured by Canon Inc.) to perform a performance test. The results are summarized in Table 2. As is clear from the description in Table 2, the toner of the present invention is excellent in offset prevention effect, fixing property, hiding power, and storage stability, and is therefore effective in obtaining a good quality copy for a long period of time. Is. On the other hand, in Comparative Examples, all of them have high melting points (120 ° C. or higher), so that the low melting point component content is low and it is considered that there is no problem in storage stability.

[0028]

[Table 2] Evaluation Method and Judgment Criteria 1) Offset Prevention Effect Using toners prepared according to respective formulations, a copying speed and a fixing temperature were set to 100 sheets / min, respectively, in the range of 140 to 240 ° C. in 5 ° C. increments using a gray scale chart. A real copy test was conducted at. The stain on the fixing roll at that time was visually determined. At the same time, the copied sample was measured using a Macbeth reflection densitometer. The fixing roll and the copy paper (plain paper) at each temperature with no stain on the non-image area were regarded as acceptable. Non-offset temperature range (roll temperature range) is 155-
240 ℃ is ○, 160-240 ℃ is △, 165-240
C was set to x. 2) Fixability (at high speed / low speed) The copying speed and the fixing temperature using the toners prepared by the respective prescriptions are 100 sheets / min at a high speed, 170-min.
200 ℃, 10 sheets / min at low speed, 120-140
A sample copied on recycled paper in steps of 10 ° C. in the range of 0 ° C. was rubbed 10 times with an eraser using a wear resistance tester manufactured by Sutherland. The load at that time is 40 g / cm ^2.
Met. The print density of the sample was measured with a Macbeth reflection densitometer. If even one measured value at each temperature was 65% or less, it was ×, 66-75% was △, and 76% or more was ○.
And 3) Hiding power The copying speed and the fixing temperature were measured with a Macbeth reflection densitometer by using a toner prepared by each prescription and copying at a copying speed and a fixing temperature of 10 sheets / min and 120 ° C, respectively. When the measured value was 65% or less, it was evaluated as x, 66 to 75% was evaluated as Δ, and 76% or more was evaluated as o. 4) Storage stability Toners prepared by the respective formulations were stored for 8 hours at 50 ° C. and 50% RH, and then sieved with 100 mesh for a certain period of time. displayed. The numerical value increases when the toner particles aggregate during storage. The main cause of this is a low melting point substance of 50 ° C. or lower contained in the toner composition. ◯: 0.5% or less of residual mesh, Δ: 0.5 to 1.0%,
X: 1.0% or more was used as the evaluation method.

[0029]

When the toner composition according to the first aspect is used, the copying speed can be increased and the fixing temperature can be lowered. In addition, it is effective in preventing offset, improving fixability and hiding power. According to the inventions of claims 2, 3, 4 and 5, the above effect becomes more desirable.

Claims (5)

[Claims] 1. A polyethylene wax containing a colorant and a binder resin as main components and having a melting point peak temperature of DSC within a range of 70 to 120 ° C. without substantially including a portion having a melting point of 50 ° C. or lower. A heating roller fixing type toner for developing electrostatic images, which is characterized in that 2. The heating roller fixing type electrostatic image developing toner according to claim 1, wherein the polyethylene wax has a melting point peak temperature of DSC within a range of 85 to 118 ° C. 3. The polyethylene wax having a number average molecular weight in the range of 300 to 2,000 and a weight average molecular weight in the range of 300 to 4,000.
The heating roller fixing type electrostatic charge image developing toner as described above. 4. The polyethylene wax is 130 ° C.
The heat roller fixing type electrostatic image developing toner according to claim 1, 2 or 3, having a melt viscosity in the range of 4 to 350 centipoise. 5. The melting point of the polyethylene wax is 50 ° C.
The heating roller fixing type electrostatic image developing toner according to claim 1, which is obtained by removing the following portions by a distillation method.