JPS63311264A - Low-temperature fixable toner for electrophotography - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a toner for dry developing electrostatic latent images such as electrophotography.

(Prior Art) Conventionally, dry developing methods include a method using a two-component developer in which toner particles are mixed with carrier particles, that is, glass beads or magnetic powder, and a method in which a two-component developer is used in which toner particles are mixed with carrier particles, that is, glass beads or magnetic powder. There is a method using component toner,
Furthermore, recently, a method using a non-magnetic component toner having excellent environmental resistance has been proposed.

As for the conventional method of manufacturing these toners.

Thermoplastic resins, colorants such as pigments and dyes, and waxes.

Additives such as plasticizers and charge control agents are mixed, heated, and melted, and the secondary agglomerated pigment or charge control agent is kneaded by applying strong shearing force, and if necessary, magnetic powder is added to the mixture. In most cases, the toner is uniformly dispersed to form a uniform composition, which is then cooled and then pulverized into 9 classifications.In recent years, there has been an active development of pressure-fixable toners that do not require heating during fixing for the purpose of saving energy. Research has been conducted and various proposals have been made. Pressure fixable toner is a so-called capsule toner consisting of a core material and an outer shell that covers the core material, and methods for producing it include spray drying, interfacial polymerization, coacervation, and phase separation methods. However, it is a combination of complicated processes such as kneading coloring agent and magnetic powder into the core material, forming the outer shell, and classifying, which leaves high costs and many issues in stabilizing quality. Due to the very high pressure of 30 to 40 kg/cm in the fixing system, problems such as glossy tube paper wrinkles occur in the image, and the size of the fixing machine is unavoidable. Furthermore, due to the properties of the capsule toner used, a small amount of toner is deposited on the surface of the photoconductor due to the frictional force that acts between the cleaning member such as a brush or blade and the toner during cleaning. As a result, the characteristics of the photoreceptor may change, such as increasing the residual potential of the photoreceptor, resulting in a deterioration of image quality.

As mentioned above, there are important problems that need to be improved regarding the pressure fixing method.

Due to the above-mentioned problems, the pressure fixing method described above is currently being replaced with a high-speed, low-temperature fixing method, which shortens the preheating time from when the copier is turned on until it is ready for copying. Powder toner that has a quick rise time and can be fixed at low temperatures is desired.

However, in order to satisfy the low-temperature fixability of toner produced by conventional pulverization methods, a resin with a low softening point must be used, resulting in decreased productivity and quality due to toner particles adhering to each other, or when the product is stored. Blocking occurs, and it is difficult to use a resin with a softening point of less than ioo''c, so it has not been practically industrialized.

(Problems to be Solved by the Invention) The present invention provides low-temperature fixing that allows the fixing temperature of the heat roller for fixing to be 100° C., preferably 80° C. or less, and prevents blocking during handling or in the copying machine. The present invention provides an electrophotographic toner that does not generate electrophotographic toner.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides toner core particles (A) containing a thermoplastic resin having a heat softening temperature of 20°C to 100''C as a main component.

2. Average particle size of one or more types selected from colorants, magnetic powders, charge control agents, and other fine particles. Fine particles (B) of OIJm or less are mixed with mechanical strain.

A low-temperature fixing electrophotography in which 50 to 500% of the surface of the core particle (A) is covered with the fine particle (B) by fixing the fine particle (B) to the surface of the core particle (A) or partially embedding it inside the core particle (A). This toner does not cause blocking even when stored at temperatures ranging from room temperature to around 60℃, and is suitable for use in fiber drums packed with 20Kg, 100~20℃.
Stored in a 0g plastic bottle.

You don't have to worry about transporting it at all, and even a copy machine weighs 1kg7.
It is capable of fixing even at low temperatures when a pressure of 2 kg or more, preferably 2 kg or more, is applied.

The thermoplastic resin for core particles (A) used in the present invention includes styrene and acrylic ester.

Copolymer systems containing styrene with methacrylic acid esters, acrylonitrile or maleic esters, polyacrylic ester systems, polymethacrylic ester systems, polyester systems, polyamide systems, polyvinyl acetate systems,
Epoxy resin, phenolic resin, hydrocarbon resin 1
Examples include well-known binder resins such as petroleum resins and chlorinated paraffins.

These can be used alone or in combination.

The heat softening temperature of these resins is 20-100"c.

Preferably, the temperature is 20 to 80°C, and in order to enable fixing at a certain desired low temperature, the molecular weight distribution is sharp, Mw/Mn is 5 or less, and the molecular weight is 3.0.
00 to 20,000 is preferred. Further, by using core particles (A) in which the thermoplastic resin is mixed with a wax known per se such as natural wax, polyethylene wax, polypropylene wax, or amide wax, low-temperature fixability can be controlled.

The fine particles (B) have an average particle size of 2.0. Colorants of c/m or less, magnetic powders, charge control agents, etc. that are themselves used as components of electrophotographic toners, and those that do not impair the properties even when used as electrophotographic toners can be used. Fine particles (B) having an average particle diameter of 2.0 μm or more are difficult to stick to the core particles (A) or to be embedded in the surface.

Coloring agents include zinc yellow, yellow iron oxide, Hansa Yellow,
Disazo Yellow, Quinoline Yellow, Permanent Yellow, Red Garla, Permanent Red, Lysol Red, Pyrazolone Red, Wochanresodo Ca Salt, Wochanresodo Mn Salt, Lakeresodo C, Lake Red D,
Brilliant Carmine 3B.

Navy blue, phthalocyanine blue, metal-free phthalocyanine,
Various pigments and dyes can be used, such as titanium oxide, carbon black.

As the magnetic powder, it is preferable to use fine magnetic powder with an average particle size of 2.0 μm or less, and various types of ferrite,
Iron and zinc such as magnetite and hematite.

Known materials such as alloys or compounds of cobalt, nickel, manganese, etc. can be used.

These magnetic powders may be classified depending on the purpose, or may be subjected to surface treatments known per se, such as hydrophobic treatment or silane coupling agent treatment.

The charge control agent is known per se, for example,
Fesoto Schwarz HBN, Nigrosine Base, Brilliant Spirit, Zabon Schwarz X.

Ceres Schwarz RG, copper phthalocyanine dye 9 alloy dye, and others C, 1, solvent black 1° 2.
3,5.7. C, 1, acid black 123.22.
23, 28.42.43. Oil black (C, 1, 2
6150), dyes such as Subiron blank, quaternary ammonium salts, naphthenic acid metal salts, fatty acid or resin acid metal soaps, etc.

Other fine particles include inorganic fine particles such as alumina, barium titanate, strontium titanate, zinc oxide, iron oxide, barium sulfate, silicon carbide, cerium oxide, silica, carbon powder, polyvinylidene fluoride, vinylidene fluoride, and vinyl fluoride. Ride.

Trifluoroethylene, ethylene, copolymers with propylene or butene, polystyrene, styrene-methyl methacrylate copolymers, xylene resins.

Petroleum resins such as polyamide, coumaron-indene resin,
Benzoguanamine resin, phenol resin, melamine resin, epoxy resin, etc. can be used.

In the present invention, the core particles (A) and the fine particles (B) collectively form a toner. Therefore, the core particle (A) is only a thermoplastic resin.

Alternatively, it is also possible to use a thermoplastic resin and, if necessary, wax together, and use colorants, magnetic powders, charge control agents, etc. as the fine particles (B), or to add various additives such as colorants, magnetic powders, etc. to the thermoplastic resin. It is also possible to prepare core particles (A) mixed with the following, and use other fine particles (B) such as a residual colorant. Also, since the charge control agent acts on the surface of the toner, it is preferable to It is preferable to fix or embed the charge control agent on the toner surface in the final step, and if the charge control agent is used by attaching magnetic powder or other relatively large particles (B) to the surface, a toner with uniform charge can be obtained. . (See Japanese Patent Application No. 62-7618 of the present patent application) For ease of understanding, preferred embodiments are listed below, but the order is not limited thereto.

(11 A thermoplastic resin and a wax are mixed and pulverized to form core particles (A) with an average particle size of 1 to 25 μm, and a coloring agent and a charge attached to the surface of the above-mentioned relatively large fine particles (B) are prepared. A method of mixing control agents simultaneously or sequentially by applying mechanical strain.

(2) Thermoplastic resin 1 A coloring agent, wax, etc. are mixed and crushed to obtain core particles (A) with an average particle size of 1 to 25 μm, and the above-mentioned relatively large fine particles (B) are attached to the surface of the core particles (A). A method of mixing a charge control agent and other necessary fine particles simultaneously or sequentially by applying mechanical strain.

(3) Thermoplastic resin and wax are mixed and pulverized to form particles, and a coloring agent, etc. is mixed with the particles by applying mechanical strain, and 1) the mixture is fixed to the particle surface or partially embedded in the particle surface in the same way as the method of the present invention. A method in which core particles (A) are prepared, and a charge control agent or a charge control agent attached to the surface of fine particles (B) is mixed therein by applying mechanical strain.

In the present invention, the obtained toner differs depending on the size of the fine particles (B), but 50 to 500%, preferably 100% or more of the surface of the core particles (A) is the fine particles (
B). This fine particle (
B) by the formation of an outer shell layer.

At low pressure, blocking of toner particles does not occur unless the temperature is considerably high, and furthermore, when pressure is applied, a toner that can be fixed at low temperatures can be obtained.

In the present invention, fine particles (B) are added to the above core particles (A).
The conditions for fixing or partially embedding on the surface using mechanical strain force are such that the core particles (A) are not fused to form a large lump, or conversely, the strain force is too large and the core particles (A) are not pulverized into fine particles. As for the specific method of satisfying both of these conditions, industrially, the operating conditions for dispersion machines such as ball mills and sand mills, and the conditions such as throughput 1 dispersion medium, etc., are set so that the above objectives are achieved. However, since ball mills and sand mills require a long time, industrially the powder is processed in a fluidized bed state.

These are mixers that move at high speed with airflow, or are equipped with impellers, hammers, etc. that give impact. The outline is the special public service 57-43
051), Atomizer-1 free crusher (Ill Nara Machinery Works), Kawasaki Heavy Industries 0@ crusher (KTM-1
), Pipe Retizer (@Nara Kikai Seisakusho), etc., and these devices can be used as they are or after being modified as appropriate to meet the purpose of the present invention. Preferably, a closed system device, such as a hybridizer, is preferably of a circulating type.

Further, it is preferable that the core particles (A) and the fine particles (B) are premixed under stirring conditions 1, which are weaker than the above-mentioned mixing treatment, for example, using a Henschel mixer. By electrostatically adhering the fine particles (B) to the core particles (A) through such preliminary mixing, the mixing process can be carried out smoothly.

This mixing process produces the effect that the fine particles (B) can be fixed to the surface of the core particle (A) or partially embedded in the surface because these particles are attached to each other, or when they are attached to a single wall, a bead, etc. It is thought that a phenomenon similar to a mechanochemical reaction in the field of inorganic chemistry is caused by collision with a dispersion medium and the like, resulting in instantaneous and local high temperatures. Such a mixing treatment has the advantage that the colorant, magnetic powder, etc. are fixed or embedded on the surface of the core particle (A) from an aggregated state to a primary particle state. By this mixing process, the system becomes E
'/K, and in some cases it may be necessary to cool the system with an external jacket or the like. When the airflow temperature within the system rises to near the Tg of the resin, particles tend to fuse together.

According to research by the present inventors, there are two possible factors for obtaining the above effects.

In the case of using the above-mentioned mixer that utilizes airflow, the speed of the airflow is the highest, and is preferably several tens of meters/second to several hundred meters/second.

In the present invention, the average particle size of the toner is 1
~25 μm, and preferably does not substantially contain toner of 0.5 μm or less and 25 μm or more.
When the amount of toner with a particle size of 0.5 μm or less increases, fluidity deteriorates and background smudges occur. Furthermore, if the amount of toner larger than 25 μm increases, two images will be distorted, reducing the commercial value.

2 In this specification, the particle size is measured using a Coulter counter TAn type (manufactured by Coulter Electronics).
is shown on a 1 volume basis.

The present invention will be explained below using specific examples. The middle part of the example shows parts by weight.

Example 1 94 parts of styrene-acrylic resin (manufactured by Vercules, Picolastink A-75, softening point 75°C, trade name) and 6 parts of low molecular weight polyethylene (manufactured by Mitsui Polychemicals, trade name Hiwax 1140H) were mixed in a Henschel mixer. The mixture is melted, kneaded, and left to cool using a two-wheeled extruder, and the kneaded mixture is coarsely crushed, and further core particles (A1) with an upper limit particle size of 25 μm or less and an average particle size of about 10 IIm are produced using a one-set jet mill. Obtained.

In addition, 100 parts of carbon powder (Sepacarbo MT-CI, trade name manufactured by Columbia Carbon Co., Ltd., average particle size 0.35 μm), 20 parts of a charge control agent (PNP-BE, trade name manufactured by Orient Chemical Al), and 200 parts of water were milled in a ball mill. The mixture was kneaded for 24 hours, filtered, and dried at 100° C. for 24 hours to obtain a carrier powder (1) carrying a charge control agent on its surface.

100 parts of the above core particles (AI), 6 parts of carrier powder (1), 2 parts of black pigment (Carbon Black, Monarch 880, trade name manufactured by Cavont), and magnetite powder (MA
T305. Product name manufactured by Toda Kogyo ■, average particle size 0゜3μm)
18 parts were pre-mixed for 5 minutes at a circumferential speed of 8 m/sec using a multi-blender mill BL-1 model (Nippon Seiki Seisakusho mixing container 800 m1), and then 100 g of this mixture was mixed using a hybridizer NNS-1 model at 6.40 rpm. It was operated for 4 minutes with negative magnetic polarity and average particle size of about 11 μm.
A toner containing substantially no particles of 5 μm or less and 25 μm or more was obtained.

The blow-off charge amount of this toner was measured using a tear/particle charge measuring device (manufactured by Hosokawa Micron ■) of -20 μc/g, and almost no toner of opposite polarity was observed.

The blocking properties of this toner were good without any problems in a 24 hour blocking test at 50°C.

In addition, this blocking test refers to 225ml of mayonnaise i! Gently put 50g of toner into a bottle (diameter 50 opened), leave it for 24 hours at 50℃ and 80RH, then turn the bottle upside down to let the toner flow out, and visually determine the presence and size of toner clumps. It is something.

Add 100 parts of this toner to silica fine powder (Nippon Aerosil ■
Manufactured by R-972. A developer was prepared by adding and mixing 0.3 parts of Microcarrier MC-30 (trade name) and 700 parts of Microcarrier MC-30 (carrier manufactured by Toyo Ink Manufacturing Co., Ltd.). This developer was placed in a copying machine manufactured by Matsushita Electric Industrial (trade name: FP 3030), and a copy was made on plain paper using a test chart.

Furthermore, as a result of testing with a commercially available heat-pressure fixing machine, the pressure was 2°5.
Kg/cm (Prescale, Fuji Photo Film)
(using pressure-sensitive paper) at a fixing temperature of 75°C.

Images with good offset properties and no background smear or fog were obtained.

Example 2 In Example 1, styrene-acrylic resin (manufactured by Arayo Kagaku ■, KR3400,
Molecular weight distribution 1. Mn/Mw=0.7, average particle size 11
μm.

Softening point: 75°C, trade name) 100 parts, carrier powder (
1) A toner was obtained by the same operation using 6 parts of carbon black, 2 parts of carbon black, and 18 parts of magnetite powder.

The blow-off charge amount of this toner was -16 μc/g, and almost no toner of opposite polarity was observed.

Regarding the blocking property of this toner, there was no problem in the blocking test described above, and the same fixing property test as in Example 1 showed that the blocking property was 8.
It was fixed at 0° C., had good fixing properties and offset properties, and an excellent image was obtained.

Example 3 In Example 1, instead of styrene-acrylic resin,
Polyamide (DPX-903/D manufactured by Henkel Hakusui ■
PX-802(7) 6/4 mixture, softening point 85℃
) was used to obtain a toner.

The blow-off charge amount of this toner was -15 .mu.c/g, and when it was measured with a single particle charge amount measuring device (manufactured by Hosokawa Miku 0-N), hardly any toner of opposite polarity was observed.

Add 100 parts of this toner to silica fine powder (Nippon Aerosil ■
Manufactured by R-972. A developer was prepared by adding and mixing 0.1 part of product name) and 30,700 parts of Microcarrier MC, and the same test as Resin 1 was conducted. As a result, the pressure was 2°5 K.
It was fixed at a fixing temperature of 60° C. under the conditions of g/cI 11, and an image with good offset properties and no background smear or fog was obtained.

Example 4 100 parts of core particles (A) used in Example 1, 6 parts of carrier powder (1), 7 parts of precipitated barium sulfate with an average particle size of 0.4 μm, and polymethyl methacrylate with an average particle size of 0.4 μm. The blow-off charge amount of the toner obtained by the same procedure as in Example 1 using 2 parts of powder and 2 parts of carbon black (same as in Example 1) was -19 μc/g.

Further, 0.1 part of fine silica powder (same as in Example 1) was added and mixed with 100 parts of this toner, and 5 parts of this mixture and 95 parts of iron powder carrier (manufactured by Nippon Tetsuko ■, F141-1530B, trade name) were mixed. A two-component developer was prepared by mixing the two components.

This developer was placed in a copying machine (DC-112) manufactured by Sanda Kogyo ■, and a copy was made on plain paper using a test chart.

The test was carried out using the same heat pressure fixing machine as in Example 1, and the pressure was 2.
．． The image was fixed at 75° C. under the conditions of g/c+w to 5, and an image with good offset properties and no background smear or fog was obtained.

Claims (1)

[Claims] 1. Toner core particles (A) mainly composed of a thermoplastic resin having a heat softening temperature of 20°C to 100°C, a colorant, a magnetic powder,
One or more types of fine particles (B) with an average particle diameter of 2.0 μm or less selected from a charge control agent and other fine particles are mixed with mechanical strain, and the fine particles (B) are coated on the surface of the core particles (A). ) by fixing or partially embedding the fine particles (
A low-temperature fixing electrophotographic toner 2 coated with B), toner core particles containing a thermoplastic resin and wax (
The toner according to claim 1, characterized in that A) is used.