JP3250569B2 - Non-magnetic one-component developing toner composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder toner composition used for electrophotographic development.

[0002]

2. Description of the Related Art Powder toners used in electrophotography are:
In electrical properties such as triboelectric charging and electrical resistance related to development and transfer performance, thermal properties related to fixing performance and heat resistance (storage stability), and powder properties such as fluidity and hardness, An appropriate level according to the use conditions is required. Conventionally, as resin materials used for powder toner, polystyrene, styrene-acrylate copolymer, styrene-butadiene copolymer,
Examples include polyester, epoxy resin, butyral resin, xylene resin, and cumarone indene resin. Various proposals have been made for the detailed design of the resin depending on the application. In particular, resins for heat roll fixing are required to have improved fixing performance to transfer paper and anti-offset performance.
The fixing performance of the toner is achieved by being heated and melted by a fixing roller or the like and binding to the transfer paper, and the anti-offset performance is such that the toner melted by the heating roller does not cause cold offset and loses viscosity. Hot offset does not occur at that time. Numerous design examples have been proposed to achieve these objectives, among which, in order to maintain viscoelasticity during heating and melting, or to suppress viscosity changes due to temperature changes, expand the molecular weight distribution, provide a crosslinked structure, and use rubber elastic materials. Technologies to which means such as application were applied were being considered. For example, Japanese Patent Application Laid-Open No. 1-267661 discloses a technique using these means.

[0003] As for electrophotography, US Pat.
297, 691, JP-B-42-23910 and JP-B-43-24748, etc., describe various methods. In general, a photoconductive substance is used and photosensitive is performed by various means. Form an electrostatic latent image on the body,
Next, the latent image is developed with a developer (toner for electrostatic charge development) to form a visible image, and, if necessary, after the visible image is transferred to paper or the like, is fixed by pressing, heating, or solvent vapor, This is to obtain a fixed image.

[0004] Many methods are known as a developing method in electrophotography. When roughly classified, fine particles (20 to 500 µm) of iron powder, ferrite, nickel, glass and the like can be roughly classified.
m), a two-component development method using a mixture of a carrier and a toner as a developer, and a one-component development method using a developer consisting of only a toner. In either method, generally, charge is injected into the toner in a triboelectric manner.

Representative examples of the two-component developing method include a cascade method described in US Pat. No. 2,618,552 and a magnetic brush method described in US Pat. No. 2,874,063. According to these methods, a good image can be obtained stably, but on the other hand, the image quality is deteriorated due to a change in the triboelectrification due to the contamination of the carrier surface by the toner or the like and a change in the mixing ratio of the carrier and the toner. This is likely to occur, and various measures must be taken in terms of equipment and materials in order to prevent this.

The one-component developing method avoids such problems of the two-component developing method. For example, US Pat. No. 4,336,318 discloses a method using an electrically insulating magnetic toner. A method for developing is described. In these methods, the charge is injected into the toner by frictional charging between the toner particles and the toner carrier and the toner thinning member, or by the frictional charging between the toner particles, so that the electrostatic latent image on the photosensitive member is Electrostatically adheres to Since this developing method does not use a carrier and does not require a device for controlling the mixing ratio between the carrier and the toner, the problems of the two-component developing method can be avoided and the developing device can be reduced in size. Having.

On the other hand, in this method, in order to form a magnetic brush layer of a toner on a metal sleeve, it is necessary to impart proper magnetic characteristics to the toner itself.
A magnetic material such as ferrite is an essential material in the toner components. The necessary content of these magnetic materials is slightly different depending on the developing conditions and the kind of the materials, but it can be generally said that the required content is 30 to 60% by weight. However, in general, the electric resistance is low,
Containing a large amount of such a magnetic material that easily absorbs moisture causes a decrease in electric resistance and a decrease in moisture resistance of the toner itself. As a result, it becomes difficult to obtain stable developing performance against environmental changes. This causes a large fluctuation in the image density or the background contamination level. Further, the fact that the proportion of the resin material as a binder contained in the toner is smaller than that of the two-component type toner is disadvantageous in terms of fixing performance in terms of design. Furthermore, considering the increasing use of color images in recent years, since many magnetic materials are colored, there is a problem that the colors that can be supported are limited, or it is difficult to obtain clear color image quality. .

In order to solve the problems of the one-component developing method using the magnetic toner, a non-magnetic one-component developing method which does not require magnetic properties of the toner has been proposed. As such a method, various devices have been studied. In many cases, a toner is attached to a developing sleeve or the like by electrostatic force, and the toner is transported to a latent image surface and developed. The development method differs greatly from the development method in that a magnetic material is not an essential component in the structure of the toner to be used, and is expected to avoid the above-mentioned various problems caused by the inclusion of the magnetic material.

[0009]

In many non- magnetic one-component developing methods, the toner is held and conveyed only by charging and electrostatic force of the toner. Therefore, when the toner is supplied to the developing sleeve or the like, the toner is instantaneously charged. Since it is necessary to charge the toner to an appropriate level, a toner charging mechanism is important in the design of the apparatus, and various methods have been proposed.
A method of passing the toner between the developing sleeve and the charging member pressed against the developing sleeve to frictionally charge the toner is generally used. In this case, it is clear that the material selection of the sleeve and the charging member needs to be sufficiently considered, but in many cases, a relatively high pressure contact condition is required. However, these conditions are such that the toner is liable to fuse due to heat generation or excessive pulverization. When these phenomena occur, the image density is reduced, and the toner conveyance to the developing sleeve is hindered. This causes various undesired image degradations such as white spots.

[0010] An object of the present invention is to provide a toner composition for non-magnetic one-component development that enables a long life of a developer while maintaining required fixing performance.

[0011]

Means for Solving the Problems The present inventors have made intensive studies to solve the above problems, and as a result, have reached the present invention. That is, in order to solve the above-mentioned problem, the present invention contains a polyester resin composed of a polybasic acid and a polyhydric alcohol containing a trivalent or more carboxylic acid as a toner component, and the glass transition point of the toner is 70 ° C. or more. The temperature at which the melt viscosity becomes 1 × 10 ⁵ poise is in the range of 140 to 170 ° C., and a stainless steel ball (SUS
No. 440C) was used as a carrier, and a developer prepared by blending 100 ml of polyvin at a toner concentration of 4% was added.
In a stirring test in which stirring is performed at 0 rpm, when the number 95% particle size before stirring and the number 95% particle size after stirring are B and B measured by a coulter counter,

[0012]

(B / A) × 100 ≧ 80%

A non-magnetic one component characterized by satisfying the following:
A developing toner composition is provided.

The polyester resin used in the present invention is produced by an esterification reaction of a polyhydric alcohol and a polycarboxylic acid. The specific method is a method which can be easily synthesized by polycondensation in a known solution, but the polyester resin used in the present invention is characterized by a polyhydric alcohol component and a dibasic acid as raw material monomers. The use of a carboxylic acid having a valency of 3 or more in addition to the components is further intended to control the esterification reaction and to impart appropriate glass transition points and melt viscosity characteristics.

The following are examples of the raw material monomer. Examples of the polyhydric alcohol component include hydrogenated bisphenol A, a propylene oxide adduct of bisphenol A, and an ethylene oxide adduct of bisphenol A. Examples of the dibasic acid component include aliphatic unsaturated dibasic acids such as maleic acid, maleic anhydride, fumaric acid, itaconic acid, and citraconic acid; phthalic anhydride, terephthalic acid, isophthalic acid, orthophthalic acid, and hexahydrophthalic anhydride. Acid, tetrahydrophthalic anhydride,
Examples include cyclohexanedicarboxylic acid, succinic acid, malonic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid and the like. Further, as a carboxylic acid component having three or more valences,
Trimellitic anhydride is preferred, but not limited thereto. As other components, an esterification catalyst, for example, zinc oxide, stannous oxide, dibutyltin oxide, dibutyltin dilaurate, etc. can be appropriately used for the purpose of accelerating the reaction.

Other components that can be used in the toner composition of the present invention include various auxiliaries such as a colorant, a charge controlling agent, and a release agent. Various components are used depending on the purpose and conditions of use. it can. In addition, as a fluidity improver, an inorganic fine powder such as silica can be used, if necessary, as a so-called external additive attached to the toner surface.

As the coloring agent, for example, carbon black, various organic and inorganic pigments and the like are used.

Examples of the charge control agent used for the purpose of imparting a positive charge include nigrosine dyes, quaternary ammonium salts, and trimethylethane dyes. Examples thereof include heavy metal-containing acid dyes such as Cr.

Further, in heat roll fixing applications, various metallic soaps and waxes may be used as necessary as an auxiliary agent for enhancing the releasing effect in order to prevent troubles due to toner adhesion to the heat roll (offset). Can be. Specific examples thereof include natural wax such as montanic acid ester wax, and polyolefin-based wax such as high-pressure polyethylene and polypropylene.

The toner composition of the present invention can be obtained by an extremely general manufacturing method, without depending on a specific manufacturing method. For example, the above components are mixed by kneading means such as a two-roll, three-roll, pressure kneader, or a twin-screw extruder, and after cooling, finely pulverized by a pulverizer such as a jet mill, and an air classifier or the like. To obtain a toner composition intended for the present invention.

In the present invention, the glass transition point is D
It was measured by SC. The melt viscosity was measured using a Shimadzu Corporation Koka type flow tester. For a large number of sheets printed during the image stability ensured in the high-speed printing, higher melt viscosity, it can be said to be desirable for one purpose and toner excessive grindability improvement of the of the present invention.

The excessively-pulverized evaluation method in the present invention is characterized by examining the toner particles diameter change of a predetermined condition, evaluation conditions and numerical limitations found in the present invention
Is indicative of the toner is running stability plane for one-component system (toner over grindability, spent occurs, the toner aggregation fixation etc.) hardness required from the preferred range of heat resistance. The evaluation conditions at this time were as follows: a stainless steel ball (SUS No. 440C)
Put 120g and 5g of toner, 10
Rotate at 0 RPM for 60 minutes. The toner is sampled from the rotated polybin, and the particle size is measured with a Coulter counter. Coulter counter is a measuring method, using a Coulter counter TAII type as a measuring machine, a measurement sample, a small amount of toner and a water spot inhibitor to a sample bottle, sufficiently wet the toner with ultrasonic waves, and further add Isoton II, Disperse and make well with ultrasound. The measurement conditions were as follows: measurement particle size range: 2.0 μm to 50.8 μm, count number: 30,000, aperture size: 100 μm
Measure with The measurement procedure is as follows: 1) Isoton II is placed in a measurement beaker and bubbles are removed by ultrasonic waves. 2) Use a pulse amplifier as the scope display and confirm that there is no noise. 3) The sample was measured with a concentration meter of 10
Measure down to about 20%. On the other hand, in consideration of the toner fixing performance required for a copy or printed matter, when a toner having a melt viscosity of 1 × 10 ⁵ poise and a temperature exceeding 170 ° C. is used, for example,
In the heat roll fixing, in order to obtain a practically sufficient fixing level, the heat roll temperature needs to be higher than 220 ° C., which causes problems in device design such as increased power consumption and accelerated heat roll deterioration. .

[0023]

The present invention will be described below in more detail with reference to Examples and Comparative Examples. In the following, “parts” and “%” represent “parts by weight” and “% by weight”, respectively.

(Resin Synthesis Example) Resin X: bisphenol A
A flask was charged with 68 mol parts, 16 mol parts of terephthalic acid, 10 mol parts of trimellitic anhydride and 0.06 mol parts of dibutyltin oxide, and reacted at 220 ° C. for about 20 hours under a nitrogen atmosphere.

(Comparative Resin Synthesis Example) Resin Y: The same starting monomer composition as resin X was charged into a flask and reacted at 200 ° C. for about 10 hours under a nitrogen atmosphere.

Resin Z: 68 mol parts of bisphenol A, 16 mol parts of terephthalic acid, 20 mol parts of trimellitic anhydride and 0.06 mol parts of dibutyltin oxide were charged into a flask and reacted at 220 ° C. for about 20 hours under a nitrogen atmosphere. .

[0027]

[0028]

[0029]

[0030]

[0031]

[0032]

[0033]

(Example 1 ) Resin X 92%, "Mogal
L "(carbon black manufactured by Cabot Corporation) 4%
TRON S-34 "(Orient charge control agent) 2%
And "Viscole 550P" (polypropylene manufactured by Sanyo Chemical Industries, Ltd.)
2% melt-kneaded, pulverized and classified to average particle size
Was 10.2 μm. Gara of the obtained toner
The transition point is 71 ° C. and the melt viscosity is 1 × 10 ⁵ poise.
Temperature is 145 ℃, B / A value of over-crushing test is 90%
Met. On the surface of this toner, “R-972” (Japan
0.5% of Erosil hydrophobic silica fine powder)
This was processed to obtain a toner. This toner is used as a non-magnetic one-component developing system printer (LP-1060S commercially available from Ricoh Company).
P3 remodeled machine, hereafter referred to as machine A), and a printing test was performed. As a result, no image deterioration was observed even after printing 5000 sheets.
Optical density D. Showed a high value of 1.4. In addition,
The image density was measured with a Macbeth reflection densitometer on the solid black portion of the printed portion. In addition, fixing is not based on the fixing device built in
The test was performed using the conditions of a heat roll fixing machine. The fixing rate was 100%. Heat roll (top) is Teflon
The lower roll is made of HTV silicon and the load is 7kg / 35
0 mm, nip width 4 mm, fixing speed at 50 mm / sec.
Tested. In addition, evaluation of fixability was performed using a commercially available
Fixing Tape ”(Sumitomo 3M / 810)
After gently rubbing with your finger and peeling off with gentle operation,
Measure the image density of that part and determine the image density before peeling the tape.
Judgment was made based on the rate of change with respect to. The judgment criteria are
If the deposition rate is 90% or more, it can be said that there is no practical problem
You. Fixing rate = (image density after peeling / image density before peeling) × 100

Example 2 90% of resin X, 6% of "Mogal L", 2% of "Bontron S-34" and 2% of "Viscol 550P" were melt-kneaded by a twin screw extruder.
After the pulverization and classification, the temperature at which the average particle size is 11.0 μm, the glass transition point is 71 ° C., and the melt viscosity is 1 × 10 ⁵ poise is 1
A toner at 55 ° C. was obtained.

"R-972" is applied to the surface of the toner by 0.5
% To obtain a toner. Example of this toner
When a printing test similar to that of Example 1 was performed, no image deterioration was observed even after printing 5,000 sheets, and the optical density O.D. D. Is 1.4
It showed a high numerical value. Also, the same fixing property as in Example 1 was exhibited.

[0037]

[0038]

[0039]

[0040]

[0041]

[0042]

(Comparative Example 1 ) In Example 1, the resin X
Except that resin Y was used instead, the same as in Example 1,
Glass transition point 62 ℃, melt viscosity 1 × 10 ⁵ poise
Is 135 ° C., and the value of B / A in the overcrushing test is 50.
% Toner was prepared. This toner was put into a non-magnetic one-component developing system printer (A machine) and a printing test was performed. As a result, the fixing property was good. However, toner adhesion occurred on the charging member at the time of printing 30 sheets, and the image density was low. Remarkable image deterioration due to reduction and white spot phenomenon was observed.

(Comparative Example 2 ) In Example 1, the resin X
Except that resin Z was used instead, the same as in Example 1
Glass transition point is 75 ℃, melt viscosity is 1 × 10 ⁵ poise
Is 180 ° C, and the value of B / A in the over-crushing test is 90.
% Toner was prepared. The toner was put into a non-magnetic one-component developing system printer (A machine) and a printing test was carried out. As a result, no toner adhered to the charging member, and the image density decreased and the white spot phenomenon was observed even after printing 5,000 sheets. However, the fixability deteriorated, and O.D. D. Is as low as about 1.0,
Further, the occurrence of partial peeling of the toner at the printing portion was recognized only by overlapping the printed matter.

[0045]

[Table 1]

[0046]

[Table 2]

The temperatures in the table are indicated by the upper heat roll surface temperature.

[0048]

As described above, according to the toner of the present invention, it has sufficient fixing performance for practical use in the non- magnetic one-component system, and has good image quality even when developing a large number of sheets. Can be provided stably.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-62-102252 (JP, A) JP-A-2-256063 (JP, A) JP-A-4-211273 (JP, A) JP-A-3-312 110571 (JP, A) JP-A-2-284159 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 9/08

Claims (4)

(57) [Claims] 1. A toner comprising a polyester resin comprising a polybasic acid containing a tri- or higher carboxylic acid and a polyhydric alcohol as a toner component, having a glass transition point of 70 ° C. or higher and a melt viscosity of 1 × 10 3 ^The temperature to become ⁵ poise is 140
And a stainless steel ball (SUS No. 440C) having a diameter of 5 mm and a carrier in the range of
In a stirring test in which a developer mixed with 00 ml polybin at a toner concentration of 4% was stirred at 100 rpm, the number 95% particle diameter before stirring measured by a coulter counter was A, and the number 95% particle diameter after stirring was A. A non-magnetic one-component developing toner composition characterized by satisfying the following formula: (B / A) × 100 ≧ 80% where B is 2. A toner having a melt viscosity of 1 × 10 ⁵ Poise
The temperature at which the temperature is in the range of 145 to 155 ° C.
The toner composition for non-magnetic one-component development as described in the above. 3. The method according to claim 1, wherein the toner comprises a polyolefin wax.
2. The non-magnetic one-component developing toner set according to claim 1, further comprising:
Adult. 4. The toner according to claim 1, wherein the toner contains a heavy metal-containing acid dye.
4. The non-magnetic one-component component according to claim 1,
Developing toner composition.