JP3129530B2 - Electrophotographic toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic toner, and more particularly, to an electrophotographic toner for a copying machine or a printer which employs heat roll fixing.

[0002]

2. Description of the Related Art In recent years, as copiers and printers using the electrophotographic system have become widespread, including in general households, low energy consumption (power consumption) has been achieved mainly for multifunctional copiers and printers. Reduction), a higher speed for the purpose of spreading to a so-called gray area located at the boundary between the printing machine and the copying machine, or a lower roll pressure for simplifying the fixing roll to reduce the machine cost is desired. ing. In addition, as copiers have become more sophisticated, since copiers equipped with a two-sided copy function and an automatic document feeder have become widespread, the fixing temperature of electrophotographic toner used in copiers and printers is low, and the There is a demand for a sheet having an excellent offset property and an excellent fixing strength to transfer paper in order to prevent stains during double-sided copying and the occurrence of stains in an automatic document feeder.

[0003] In response to the above demands, in the prior art, there have been proposed, for example, ones in which the molecular weight and molecular weight distribution of the binder resin are improved as described below.

Specifically, attempts have been made to lower the molecular weight of the binder resin and lower the fixing temperature. However, the lowering of the molecular weight lowers the melting point but also lowers the viscosity at the same time, so that there has been a problem that an offset phenomenon to the fixing roll occurs. In order to prevent this offset phenomenon, a method of widening a low molecular weight region and a high molecular weight region of the molecular weight distribution of the binder resin, or a method of cross-linking a polymer portion has been performed. However, in this method, the glass transition point of the resin must be lowered in order to have sufficient fixability, and it is inevitable that the storage stability of the toner is impaired. Further, when the amount of the low-molecular-weight portion of the binder resin is increased, the toner itself becomes brittle, and stains during double-sided copying and stains in the automatic document feeder have occurred.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an electrophotographic apparatus which can fix at a low fixing temperature, does not cause any practical problem in offset properties, and has excellent fixing strength to transfer paper. To provide a toner for use.

[0006]

Means for Solving the Problems The present invention contains a styrene copolymer and a vegetable wax, a styrene copolymer, a peak position of molecular weight in the GPC chromatogram 10 ³ to 10 ⁴ and ¹⁰⁵ to mix with the polymer a to the at least one organic polymer B in the respective areas of the ⁷
And the mixing ratio of the polymer A and the polymer B is 7
0:30 to 90:10, and the melting start temperature is 1
An electrophotographic toner, wherein the toner has a softening point of 105 ° C. or less.

Hereinafter, the present invention will be described in detail. The styrenic copolymer in the present invention has a molecular weight peak position of 10 ³ to 1 on a chromatogram measured by gel permeation chromatography (hereinafter referred to as GPC).
It has at least one in each of the regions 0 ⁴ and 10 ⁵ to 10 ⁷ , and has no peak position outside the range of the region. In this case, the peak position of the molecular weight is 1
In less than 0 ^3, it becomes difficult to maintain good offset resistance. On the other hand, if the peak position of the molecular weight exceeds 10 ⁷ , the toner is not sufficiently dissolved by the fixing roll,
The state becomes the same as the low-temperature offset.

In the present invention, the molecular weight at the peak position of the molecular weight distribution of the styrene copolymer is a value measured by GPC under the following conditions. That is, a solvent (tetrahydrofuran) is allowed to flow at a flow rate of 1 ml per minute at a temperature of 25 ° C., and 8 mg of a tetrahydrofuran sample solution having a concentration of 0.4 gr / dl is injected as a sample weight and measured. In the measurement of the molecular weight of the sample, the molecular weight distribution of the sample is within a range in which the logarithm of the molecular weight and the count number of a calibration curve prepared from several monodisperse polystyrene standard samples are linear. Select In this measurement, the reliability of the measurement was based on the NBS706 polystyrene standard sample (Mw = 28.8 × 10 ⁴ , Mn = 1) under the above measurement conditions.
Mw / Mn of 3.7 × 10 ⁴ , Mw / Mn = 2.11)
Can be confirmed by being 2.11 ± 0.10.

The styrenic copolymer in the present invention is obtained by synthesizing the following monomers by a suspension polymerization method, an emulsion polymerization method, a solution polymerization method, a bulk polymerization method or the like. As the monomer, styrenes such as styrene, α-methylstyrene and chlorostyrene, acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, octyl acrylate and alkyl acrylate, Examples thereof include methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, octyl methacrylate, stearyl methacrylate, glycidyl methacrylate, and alkyl methacrylate. Other copolymerization components include acrylonitrile, maleic acid,
Vinyl monomers such as maleic acid ester, methyl methacrylate, methyl acrylate, vinyl chloride, vinyl acetate, vinyl benzoate, vinyl methyl ketone, vinyl hexyl ketone, vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, etc. 30% by weight
It may be contained below.

[0010] Such a styrenic copolymer can be obtained by the above-mentioned GP.
In the C chromatogram, the molecular weight is 10 ³ to 10 ⁴ and 1
It is prepared by mixing a polymer A and a polymer B each having at least one peak position in the region of 0 ⁵ to 10 ⁷ .
The mixing ratio of the polymer A and the polymer B is 70:30 to 9
A ratio of 0:10 is necessary because the fixing property and the non-offset property are good. When the proportion of the polymer A is more than 90%,
There is no effect of mixing a low molecular weight polymer and a high molecular weight polymer to broaden the molecular weight distribution and improve non-offset properties.
On the other hand, if the proportion of the polymer B is more than 30%, the amount of the high molecular weight polymer increases, so that a large amount of heat energy is required for fixing on the heat fixing roll, which is not preferable.

Next, as the plant wax used in the present invention, candelilla wax, carnauba wax,
Rice wax, wood wax and the like. Vegetable wax has a relatively low softening point compared to animal wax, mineral wax, petroleum wax or synthetic wax, and dissolves sharply in heat. By lowering the softening point of the toner, even a low-temperature heat fixing roll sufficiently dissolves and enables low-energy fixing. The melting start temperature of the vegetable wax is preferably 80 ° C. or lower, because the melting start temperature and the softening point of the toner for electrophotography of the present invention can be adjusted to predetermined numerical limited ranges.

The electrophotographic toner of the present invention must have a melting start temperature of 105 ° C. or lower and a softening point of 125 ° C. or lower. This is because electrophotographic toners having a dissolution starting temperature or softening point higher than the above values do not dissolve with a low-temperature heat fixing roll, fail to provide sufficient fixing strength to transfer paper, and deteriorate rubbing resistance. It is. The melting start temperature and softening point referred to in the present invention refer to values measured by the following measuring instrument and measuring conditions. The melting start temperature refers to the temperature at which the plunger starts to lower, and the softening point refers to the temperature at the middle of the travel distance from the start to the end of the plunger's lowering. Measuring machine: Koka type flow tester CF-500 manufactured by Shimadzu Corporation Measurement conditions: Plunger: 1 cm ² Die diameter: 1 mm Die length: 1 mm Load: 20 kgF Preheating temperature: 50 to 80 ° C Preheating time: 300 sec Speed: 6 ° C / min

As the binder resin for the electrophotographic toner of the present invention, in addition to the styrene copolymer, a polyethylene resin,
A resin such as an epoxy resin, a silicone resin, a polystyrene, a polyamide resin, a polyurethane resin, and a polyester resin may be added.

The electrophotographic toner of the present invention is a particle obtained by appropriately dispersing and containing other toner components such as a colorant, a magnetic substance, and a property improving agent in the styrene copolymer and the vegetable wax as described above. Having an average particle size of 5 to 3
The range is 0 μm. Further, a toner may be constituted by adding and mixing a flow improver composed of silica fine powder or the like to the particles thus obtained. Colorants include carbon black, nigrosine dye, aniline blue, coco oil blue, chrome yellow, ultramarine blue, Dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black rose bengal and the like. Mixtures and others can be mentioned. These colorants need to be contained in a sufficient ratio to form a visible image having a sufficient density.
The ratio is about 1 to 20 parts by weight with respect to 0 parts by weight.

The magnetic material does not include ferrite, magnetite and other ferromagnetic metals or alloys such as iron, cobalt and nickel, compounds containing these elements, or ferromagnetic elements. Alloys that exhibit ferromagnetism when subjected to various heat treatments, such as manganese-copper-aluminum, manganese-copper-tin, and other alloys of the type called Heusler alloys containing manganese and copper, or chromium dioxide, and the like. be able to. These magnetic materials are uniformly dispersed in the binder resin in the form of fine powder having an average particle size of 0.1 to 1 micron. The content is 20 to 7 parts per 100 parts by weight of the toner.
0 parts by weight, preferably 40 to 60 parts by weight.

Examples of the property improving agent include a charge control agent, an anti-offset agent, a lubricant for improving fluidity, and the like.

The toner for electrophotography of the present invention is mixed with a carrier composed of iron powder, ferrite, granulated magnetite and the like to form a two-component developer. When a magnetic material is contained, the toner is mixed with the carrier. Instead, it may be used as it is as a one-component developer for developing an electrostatic image, or may be mixed with a carrier and used as a two-component developer.

[0018]

The present invention will be described below with reference to examples. In the examples, parts are parts by weight. Example 1 Weight average molecular weight 9 × 10 ⁵ and number average molecular weight 3.9 × 1
0 ⁵ of styrene - butyl copolymer A30 parts of acrylic acid, the weight-average molecular weight 8 × 10 ³ and a number average molecular weight 2.7
× 10 ³ styrene-butyl acrylate copolymer B70
Were mixed to obtain a styrene-based copolymer having peak positions at molecular weights of 7.5 × 10 ⁵ and 4.5 × 10 ³ in the GPC chromatogram. Next, the styrene-based copolymer and other raw materials are mixed in a supermixer at the following mixing ratio, melt-kneaded, pulverized and classified to obtain particles having an average particle size of 11 μm, 0.3 parts of silica (trade name: R-972, manufactured by Nippon Aerosil Co., Ltd.) was attached to the surface of the particles by a Henschel mixer to obtain a negatively chargeable electrophotographic toner of the present invention.

Example 2 Weight average molecular weight 9 × 10 ⁵ and number average molecular weight 3.9 × 1
0 ⁵ of styrene - butyl copolymer A20 parts of acrylic acid, the weight-average molecular weight 8 × 10 ³ and a number average molecular weight 2.7
× 10 ³ styrene-butyl acrylate copolymer B80
Were mixed to obtain a styrene-based copolymer having peak positions at molecular weights of 7.5 × 10 ⁵ and 4.5 × 10 ³ in the GPC chromatogram. Next, the styrene-based copolymer and other raw materials are mixed in a supermixer at the following mixing ratio, melt-kneaded, pulverized and classified to obtain particles having an average particle size of 11 μm, 0.3 parts of silica (trade name: R-972, manufactured by Nippon Aerosil Co., Ltd.) was attached to the surface of the particles by a Henschel mixer to obtain a negatively chargeable electrophotographic toner of the present invention.

Example 3 Weight average molecular weight 9 × 10 ⁵ and number average molecular weight 3.9 × 1
0 ⁵ of styrene - butyl copolymer A10 parts of acrylic acid, the weight-average molecular weight 8 × 10 ³ and a number average molecular weight 2.7
× 10 ³ styrene-butyl acrylate copolymer B90
Were mixed to obtain a styrene-based copolymer having peak positions at molecular weights of 7.5 × 10 ⁵ and 4.5 × 10 ³ in the GPC chromatogram. Next, the styrene-based copolymer and other raw materials are mixed in a supermixer at the following mixing ratio, melt-kneaded, pulverized and classified to obtain particles having an average particle size of 11 μm, 0.3 parts of silica (trade name: R-972, manufactured by Nippon Aerosil Co., Ltd.) was attached to the surface of the particles by a Henschel mixer to obtain a negatively chargeable electrophotographic toner of the present invention.

Comparative Example 1 A comparative electrophotographic toner was prepared in the same manner as in Example 1 except that the styrene-butyl acrylate copolymer A was not used and the styrene-butyl acrylate copolymer B was changed to 100 parts. I got

Comparative Example 2 A comparative electrophotographic toner was prepared in the same manner as in Example 1 except that the styrene-butyl acrylate copolymer B was not used and the styrene-butyl acrylate copolymer A was 100 parts. I got

Comparative Example 3 An electrophotographic toner for comparison was obtained in the same manner as in Example 1, except that no rice wax was used.

Comparative Example 4 Weight average molecular weight 9 × 10 ⁵ and number average molecular weight 3.9 × 1
⁵ parts of styrene-butyl acrylate copolymer A5,
Weight average molecular weight 8 × 10 ³ and number average molecular weight 2.7 × 1
0 ³ styrene - mixing a butyl acrylate copolymer B95 parts, molecular weight in the GPC chromatogram 7.5
Styrene-based copolymers having peak positions at × 10 ⁵ and 4.5 × 10 ³ were obtained. Next, the styrene-based copolymer and other raw materials were mixed in a supermixer at the following mixing ratio, melt-kneaded, crushed and classified to have an average particle diameter of 11 μm.
After obtaining particles of m, 0.3 parts of hydrophobic silica (trade name: R-972, manufactured by Nippon Aerosil Co., Ltd.) is adhered to the surface of the particles using a Henschel mixer to prepare a negatively chargeable electrophotographic toner for comparison. Obtained.

Comparative Example 5 A comparative electrophotographic toner was obtained in the same manner as in Example 1, except that the rice wax was replaced by 5 parts of polyethylene wax (melting start temperature: 81.1 ° C.).

Next, the following items were tested for the above-mentioned Examples and Comparative Examples. (1) Fixing Strength First, 60 parts of each of the electrophotographic toners obtained in the above Examples and Comparative Examples and 100 parts of a ferrite carrier without a resin coating (trade name: FL-1020, manufactured by Powder Tech) were mixed. To produce a developer. Next, a commercially available copier (trade name: SF-980, manufactured by Sharp Corporation) is used by using the developer.
In 0), a plurality of belt-shaped unfixed images each having a length of 2 cm and a width of 5 cm were formed on A4 transfer paper. Next, a fixing device including a heat fixing roll having a surface layer formed of Teflon and a pressure fixing roll having a surface layer formed of silicone rubber was set to a pressure of 5 mm.
Kg / cm ² and roll speed 450mm / sec
And set the temperature of the heat fixing roll to 16
The temperature was set to 0 ° C., and the toner image on the transfer paper on which the unfixed image was formed was fixed. Then, the formed fixed image was rubbed with a cotton pad, and the fixing strength was calculated according to the following equation, which was used as an index of low energy fixing property. (2) High-temperature offset property The set temperature of the heat fixing roll of the fixing device is adjusted to 220 ° C. to fix the toner image of the transfer sheet on which the unfixed image is formed, and the toner image on the margin of the transfer sheet The toner stain was observed. Table 1 shows the results of the examples and the comparative examples obtained by the above test. Table 1 also shows the melting start temperature and the softening point of the electrophotographic toners obtained in each of Examples and Comparative Examples. Is indicated by x.

[0027]

[Table 1]

As is clear from the results shown in Table 1, the electrophotographic toner of the present invention had a fixing strength of 87% or more even at a low temperature of the heat fixing roll of 160 ° C., and no high-temperature offset occurred. On the other hand, the comparative electrophotographic toner could not maintain both the fixing strength and the high-temperature offset property.

[0029]

As described above, the toner for electrophotography of the present invention has sufficient fixing strength even when the temperature of the heat fixing roll is low and does not cause high-temperature offset. Therefore, the effects such as reduction in machine cost due to lower roll pressure and increase in copying speed can be achieved.

Continued on the front page (72) Inventor Koji Nakayama 3-1, Yosoba-cho, Shizuoka-shi, Shizuoka Pref. Inspector in the chemical product factory of Hamakawa Paper Mill Kanae Isogai (56) References JP-A-3-1222659 (JP JP-A-4-211271 (JP, A) JP-A-3-91764 (JP, A) JP-A-3-139664 (JP, A) JP-A-4-78864 (JP, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 9/08

Claims (2)

(57) [Claims] [Claim 1] contains a styrene copolymer and a vegetable wax, a styrene copolymer, a peak position of molecular weight in the GPC chromatogram 10 ³ to 10 ⁴ and 10 ⁵ to 10 ^7, respectively is obtained by mixing a polymer a you at least one chromatic <br/> polymer B in the region, the polymerization
The mixing ratio of the polymer A and the polymer B is from 70:30 to 90:10
And a melting start temperature of 105 ° C. or less and a softening point of 125 ° C. or less. 2. The melting start temperature of the vegetable wax is 8
2. The electrophotographic toner according to claim 1, wherein the temperature is 0 [deg.] C. or less.