JPH0119143B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a one-component developer used to develop an electrical latent image or a magnetic latent image in electrophotography or electrostatic printing, and particularly to a one-component developer used in pressure fixing. The present invention relates to suitable developer compositions.

Conventionally, as an electrophotographic method, U.S. Patent No. 2297691
Specification of No. 42-23910 and Special Publication No. 1973
Many methods are known, as described in Japanese Patent No. 24748, etc., but in general, a photoconductive substance is used to form an electrical latent image on a photoreceptor by various means, and then the A latent image is developed using toner, and after the toner image is transferred to a transfer material such as paper as necessary, it is fixed by heat, pressure, solvent vapor, etc. to obtain a copy.

Various methods are also known for visualizing electrical latent images using toner.

For example, the magnetic brush method described in U.S. Pat. No. 2,874,063, the cascade development method described in U.S. Pat. Many developing methods are known, such as the developing method.

The developed toner image is transferred and fixed onto a transfer material such as paper, if necessary. Methods for fixing toner images include a method in which the toner is heated and melted using a heater or a heated roller, and then fused and solidified on the support, a method in which the binder resin of the toner is softened or dissolved with an organic solvent, and then fixed on the support, and a method in which the toner is fixed on the support by applying pressure. A method of fixing toner on a support by using a method is known.

Conventionally, the toner used here is a fine powder in which dyes and pigments are dispersed in natural or synthetic resin. Furthermore, it is also known to use fine developing powder to which a third substance is added for various purposes. Furthermore, toner materials are selected to be suitable for each fixing method, and generally, toners used for a particular fixing method cannot be used for other fixing methods.

In particular, it is almost impossible to transfer the toner used in the conventionally widely used heat fusion fixing method using a heater to a hot roller fixing method, a solvent fixing method, a pressure fixing method, or the like. Therefore, toners suitable for each fixing method are being researched and developed.

The method of fixing toner under pressure is based on US Patent No.
It is described in specification No. 3269626, Japanese Patent Publication No. 46-15876, etc., and is energy saving, non-pollution, copying can be done without waiting time when the copier is turned on, there is no risk of burning copies, and high speed. It has many advantages such as being able to be fixed and having a simple fixing device.

However, there are problems such as toner fixability and offset phenomenon to the pressure roller, and various research and development efforts are being carried out to improve toners for pressure fixing.

For example, Japanese Patent Publication No. 44-9880 describes a pressure fixing toner containing an aliphatic component and a thermoplastic resin;
-17739 and No. 52-108134, etc., describe a capsule-type pressure fixing toner containing a soft material in the core, and JP-A-48-75033 describes a toner containing a sticky polymer and a soft polymer block. Pressure-fixed toners using copolymers have been described.

However, it is easy to manufacture, has sufficient pressure fixing performance, does not cause any offset phenomenon to the pressure roller, and has stable developing performance and fixing performance even after repeated use. A practical pressure fixing toner that does not adhere to the body surface, does not aggregate or form cakes during storage, and has good storage stability has not been obtained. Furthermore, recently, a method has been used in which electrostatic latent images are developed using a one-component developer that contains magnetic fine particles in the toner and does not use carrier particles, but in this case, the toner binding resin contains magnetic fine particles. Dispersibility and adhesion with the toner, as well as impact resistance and fluidity of the toner, are required.

In addition, Japanese Patent Application Laid-Open No. 54-42141, which was previously proposed by the present applicant,
No. 55-18656, when developing by frictional charging between a one-component developer and a developing sleeve roller, the insulating material separates due to impact or use over time, causing triboelectricity. Single-component developers also have many problems, such as when they adhere to the sleeve roller and accumulate, affecting development durability.

Also, Special Publication No. 11493, Special Publication No. 11493, Special Publication No. 51-11493,
Publication No. 35867, Japanese Patent Application Laid-Open No. 1983-64931, Japanese Patent Application Publication No. 1987-64931
It is known that polyethylene resin is a material with excellent pressure fixing properties, as described in Japanese Patent Laid-Open No. 53-6034 and Japanese Patent Laid-Open No. 53-6039. However, no developer has been found that exhibits good pressure fixing properties under a linear pressure of about 10 to 15 kg/cm and has development durability that can withstand tens of thousands of copies. An object of the present invention is to provide a developer that has stable developing performance such as chargeability and pressure fixing performance even after repeated use, and has excellent durability.

Another object of the present invention is to provide a developer that has good pressure fixing performance and does not cause offset to the pressure roller.

Furthermore, another object of the present invention is to provide a developer which has excellent properties as described above even when used as a magnetic toner, and which can be electrostatically transferred.

Another object of the present invention is to provide a developer which has good storage stability and does not adhere to the surface of a photoreceptor or sleeve, nor does it aggregate or form a cake during storage.

Specifically, the present invention uses pressure fixable toner particles with an average particle size of 10 to 15 μm and a primary average particle size of 5 to 100 μm.
A fluidity improver made of colloidal silica or alumina powder granulated to a size of 0.1 to 20 times the average particle size of the toner particles so that it can be gradually loosened by stirring in the developing device. This invention relates to a one-component developer.

In pressure fixable toners, fixability and development durability are contradictory. That is, if the fixing property is increased, the fluidity of the toner becomes poor, resulting in a markedly poor development durability, and in extreme cases, images may not be reproduced after only a few sheets. In order to prevent paper curling, excessive glossiness, changes in paper thickness, etc., toners that can be fixed with a linear pressure of 10 kg/cm or less are currently being developed, which increases development durability. This is strongly requested.

That is, in order to increase the development durability of pressure-fixed toner, a mixture of toner and a fluidity improver is used, but the fluidity improver is extremely smaller than the toner particle size (actually about 5 to 50 mμ). Using
The initial copy image is good, but during the durability test of the copy, this fluidity improver is embedded in the toner or detached, so the fluidity improver that is actually necessary for image reproduction tends to be insufficient. As a result, the image density becomes extremely low. This phenomenon is thought to occur because the fluidity improver is smaller and harder than the toner binder, and it occurs more severely in pressure-fixed toners with a linear pressure of 10 kg/cm or less as described above.

In the present invention, since the developer contains a granulated fluidity improver, when copying is repeated, the developer in the developing device is agitated, and the granulated fluidity improver is agitated. Since the agent is gradually loosened into single particles of the fluidity improver, and a constant amount of single grains of the fluidity improver are always present in the developer, durability is significantly extended.

In the present invention, colloidal silica or alumina particles having a primary average particle diameter of 5 to 100 mμ are granulated so as to be gradually loosened by stirring the developer in the developing device, and are used as the fluidity improver. .
As for the granulation method, these may be aggregated alone or solidified with a resin or the like. Various natural or synthetic resins can be used, and the softer the resin, the easier it is to unravel and the more durable the developer is.

The size of the granulation fluidity improver is determined by the average particle size of the toner.
A value of 0.1 to 20 times (preferably 5 to 15 times) was good. If it is smaller than 0.1 times, sufficient durability cannot be obtained, and if it is more than 20 times, streaks (due to the uniform distribution of toner being disturbed) may occur on the developing sleeve of the developing device. In order to obtain this granulation size, classification may be performed as necessary.

The content of the granulated fluidity improver in the developer is preferably 0.1 to 10 parts by weight (more preferably 0.3 to 3 parts by weight) per 100 parts by weight of the toner. It is. If it is less than 0.1 part by weight, the durability will not be sufficient, and if it is more than 10 parts by weight, the fixing performance will be poor.

The toner particles contain a binder, a colorant, and, if necessary, magnetic powder and additives. In the present invention, toner particles having an average particle size of 10 to 15 microns are used.

In the case of a pressure fixing toner, the binder should preferably be one that easily fixes to paper fibers when pressure is applied, and particularly preferred binders include polyethylene, polypropylene, and ethylene.
Ethylene polymers with a melt viscosity of 10 to 106 cps at 140°C, such as propylene copolymers, ethylene-acrylic copolymers, and ethylene-vinyl acetate; rubbers, such as styrene-isoprene copolymers, and styrene-butadiene copolymers. ; Elastomers such as polyurethane elastomer and saturated linear polyester; stearic acid, oleic acid, myristic acid,
These include fatty acids and derivatives thereof such as stearamide, oleic acid amide, and zinc stearate; waxes such as paraffin wax and carnauba wax;

As seen in the Examples below, it is particularly preferable to use an ethylene polymer or wax as the pressure fixing binder.

As the coloring agent, known dyes and pigments such as carbon black, iron black, phthalocyanine blue, ultramarine blue, quinacridone, and benzidine yellow can be used.

Furthermore, when used as a magnetic toner, it may also serve as a coloring agent, but ferromagnetic elements and alloys containing them, compounds such as magnetite, hematite, ferrite, etc., alloys of iron, cobalt, nickel, manganese, etc. It may also contain magnetic powders conventionally known as magnetic materials such as compounds and other ferromagnetic alloys. Furthermore, nigrosine, metal complex salts, colloidal silica powder, fluororesin powder, etc. may be added for the purpose of charge control, prevention of aggregation, and other purposes.

Examples will be shown below. Parts are parts by weight.

Example 1 20 parts of ethylene ethyl acrylic copolymer and 30 parts of castor wax were dissolved in a monomer of styrene-butyl methacrylate (30:20 parts by weight), and the polymerized polymer was prepared as follows: 100 parts Charge control agent 2 parts Magnetic material 50 parts Above The mixture was kneaded using a roll mill heated to 130°C, cooled, and finely pulverized using a zigzag classifier to obtain a toner having an average particle size of 12.5μ.

Meanwhile, 60 g of hydrophobic colloidal silica (R972 manufactured by Nippon Aerosil Co., Ltd.) was added to 100 ml of a 2% MEK solution of styrene-butyl acrylate-maleic anhydride resin (Daido Kogyo Co., Ltd. I put it in and let it air dry. Next, after air drying, the mixture was crushed in a mortar to obtain a granulated fluidity improver having an average particle size of 125 μm.

A developer was obtained by mixing 1.2 parts by weight of the granulated fluidity improver with 100 parts by weight of the toner.

Apply this developer to an electronic copying machine (manufactured by Canon, product name).
When copying was carried out under NP120 (fixing pressure, linear pressure 25 kg/cm), the maximum image density was within 1.2 ± 0.2 from the initial to 100,000 copies, and the images were clear.

As a comparative example, when the ungranulated hydrophobic colloidal silica was mixed in the same manner as in Example 1 and copies were made using the above-mentioned copying machine, only about 100 clear images were reproduced. .

Example 2 Polyethylene wax 50 parts Paraffin (melting point 70°C) 50 parts Charge control agent 2 parts Magnetic material 50 parts The above mixture was kneaded using a roll mill heated to 130°C, and after cooling, it was milled using a pulverizing zigzag classifier. A toner with an average particle size of 10 μm was obtained.

On the other hand, the granulated fluidity improver could be treated in the same manner as in Example 1.

Next, 2 parts of the granulated fluidity improver was mixed with 100 parts by weight of the above toner to prepare a developer.

When this developer was subjected to copy durability using the same electronic copying machine as in Example 1, the maximum image density was within 1.4 ± 0.3 from the initial to 3000 copies, and the images were clear and at the same time the linear pressure was 10 kg. /cm fixed.

As a comparative example, when the ungranulated hydrophobic colloidal silica was mixed in the same manner as in Example 2 and copies were made using the above-mentioned copying machine, the density became extremely low after only 3 copies were made.

Example 3 Using the toner of Example 1, a granulated fluidity improver was prepared according to the following procedure.

Colloidal silica (WACKER HDK H-
15) 100 g of cyclized rubber (Alpex CK450, manufactured by Hoechst) was added to 100 ml of a 1% toluene solution, stirred, and then the gel was placed in a vat and air-dried at 50°C. Next, after air-drying, grind the average particle size in a mortar and
A granulated fluidity improver of 160μ was obtained.

Next, 1.0 part of the granulated fluidity improver was mixed with 100 parts of the toner of Example 1 to obtain a developer. When this developer was subjected to copy durability using the same electronic copying machine as in Example 1, the maximum image density was within 1.3±0.2 from the initial stage to 100,000 copies, and the images were clear.

Example 4 In addition to the toner and granulated fluidity improver of Example 1, a fluidity improver R972 manufactured by Nippon Aerosil Co., Ltd.
were mixed at a ratio of 100 parts: 1.2 parts: 0.4 parts to obtain a developer.

When the same test as in Example 1 was conducted, Example 1
Similar good results were obtained.

Claims (1)

[Scope of Claims] 1 Pressure-fixable toner particles with an average particle size of 10 to 15 μm and colloidal silica or alumina powder with a primary average particle size of 5 to 100 μm are gradually loosened by stirring in a developing device. average particle size
A one-component developer characterized by containing a fluidity improver granulated to a size of 0.1 to 20 times. 2. The one-component developer according to claim 1, wherein the pressure-fixable toner particles are magnetic toner containing magnetic fine particles. 3. The one-component developer according to claim 1 or 2, wherein the pressure-fixable toner particles contain an ethylene polymer or wax as a pressure-fixable binder.