JPS63182660A - Toner for developing electrostatic latent image - Google Patents

Abstract

PURPOSE:To obtain a toner which permits low-temp. fixing, good blocking resistance, obviates filming and has excellent durability by embedding small grain size particles having low pressure deformability into the surface of large grain size base body particles having high pressure deformability. CONSTITUTION:The small particles B which have the lower pressure deformability than the base body particles A and the smaller grain size are embedded and coated to the depth below the grain size of the small particles B into and on the surface of the base body particles A having the pressure deformability larger than the pressure deformability of the small particles B and the larger grain size. The particles A are formed by using wax or resin having the pressure deformability higher than the pressure deformability of the particles B and the larger grain size as an essential component and adding a coloring agent and/or magnetic material at need thereto. Said particles are mainly used for the purpose of low- pressure fixing, coloring, etc. On the other hand, the small particles B are formed by using an org. or inorg. material having the smaller pressure deformability than the pressure deformability of the particles A and the smaller grain size as the essential component and likewise adding the coloring agent and/or magnetic material thereto. Said particles are mainly used for the purpose of improving blocking resistance, preventing filming of the toner to a photosensitive body, carrier, etc., and assuring good electrostatic chargeability.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a one-component type or two-component type pressure fixable toner using two types of particles having different pressure deformability and particle size.

Conventionally, pressure-fixing toners used for developing electrostatic latent images are generally composed of a pressure-deformable material as a main component, to which colorants and carriers are added as necessary. As pressure deformable materials, soft materials such as wax and polyvinyl acetate are generally used because they can be fixed at low pressure and have good fixing properties. However, this type of pressure fixable toner (1) tends to cause so-called blocking, in which toner particles fuse together during storage or use, and (2) during copying, it is crushed by contact with the carrier to form spent toner, which further 3) It adheres to the photoreceptor and carrier and forms a film (so-called filming), degrading their performance. 3) It is easy to scatter during development, so repeated use causes compositional changes and decreases the amount of charge. There were drawbacks such as deterioration of image quality and fixing performance.

Therefore, in order to eliminate these drawbacks, for example, Japanese Patent Application Laid-Open No. 52-9
No. 8531 proposes a toner in which a pressure-deformable material is used as a core material and is encapsulated in a hard resin shell material, but in the case of this toner, the walls of the shell material cannot be sufficiently destroyed during fixing. The internal pressure-deformable material does not flow out smoothly onto the paper, which tends to cause poor fixing. Also, JP-A-59-223450 and JP-A-52-130332
No. 2, a toner in which a release material such as fine silica powder is dispersed in a pressure-deformable material is proposed, but low-pressure fixing is difficult with this toner due to the inclusion of the release material.

The object of the present invention is to enable low-pressure fixing, have good anti-blocking properties, not cause filming on the photoreceptor or carrier, and maintain good charging properties even after repeated use. To provide a durable toner for developing electrostatic latent images.

The toner for developing electrostatic latent images of the present invention is as shown in FIG.
Small particles B, which have less pressure deformability than the base particles A and have a smaller particle size, are placed on the surface of the base particles A, which have a larger pressure deformability and a larger particle size than the base particles B. It is characterized by being buried and covered at a depth of .

In the present invention, the base particles A have greater pressure deformability than the small particles B, and are mainly composed of a wax or resin having a larger particle size, to which a colorant and/or a magnetic substance is added if necessary, and are mainly made of Used for low pressure fixing, coloring, etc. On the other hand, the small particles B have smaller pressure deformability than the base particles A and mainly consist of an organic or inorganic substance with a small particle size,
If necessary, a coloring agent and/or a magnetic substance may be added as in the case of base particle A, mainly to improve blocking resistance, prevent toner from filming on photoreceptors, carriers, etc., and ensure good charging properties. used for.

Here, it is preferable that the base particles A further have heat softening properties, and are preferably three times or more of the average particle size. Note that the average particle diameter of the base particles A is specifically 5 to 25
Approximately μm is appropriate.

Specific examples of base particles A include natural paraffin, microcrystalline wax, polyethylene wax, chlorinated naphthalene, synthetic wax, polyvinyl acetate, acrylic resin, styrene-butadiene copolymer, ethylene-vinyl acetate copolymer, and ethylene-vinyl acetate. Examples include acrylic copolymers, vinyl acetate-acrylic copolymers, epoxy resins, urethane resins, polyisobutylene, polyamides, low molecular weight styrene resins, ester rubbers, rosin ester resins, and mixtures thereof. Others: stearic acid, palmitic acid, myristic acid, capric acid, lauric acid, stearic acid amide, myristic acid amide, oleic acid amide, lauric acid amide, capric acid amide, octanamide, hexanamide, methylene bis stearamide, ethylene It is also possible to use lubricants such as bisstearamide, hydrogenated tallow amide, butyl stearate, ethylene glycol monostearate, methyl hydroxystearate, glycerol monostearate, hydrogenated castor oil, cetyl alcohol, stearyl alcohol, and ethylene glycol. . It is also possible to add inorganic fine powder such as hydrophobic or hydrophilic silica, aluminum oxide, titanium oxide, zinc oxide, talc, etc. as a grinding aid for forming particles.

Coloring agents include carbon black (e.g. channel black, acetylene black, lamp black, etc.), nigrosine dye, aniline blue, calco oil blue, phthalocyanine blue, chrome yellow, ultramarine blue, quinoline yellow, methylene blue chloride, monastral blue, malachite green. Examples include Ozalate, Lamp Black, Rose Bengal, Monastral Red, and Sudan Black BM.

Magnetic materials include metal powders such as cobalt, iron and nickel; aluminum, cobalt, copper, iron, lead, nickel,
Magnesium, tin, zinc, gold, silver, selenium, titanium,
Examples include metals such as tungsten and zirconium and mixtures thereof; metal oxides such as iron oxide and nickel oxide and metal compounds containing the same; ferromagnetic ferrite and mixtures thereof.

On the other hand, as for the small particles B, it is preferable that the average particle diameter is less than 173 times the base particle A as described above. Note that if this average particle diameter is ⅓ or more of the base particle A, the fixing properties will deteriorate rapidly.

Specific examples of small particles B include organic ones such as polystyrene, polyvinyltoluene, styrene-butadiene copolymer, styrene-acrylic acid copolymer, and styrene-
Polymers or copolymers of styrene or its substituted products such as maleic anhydride copolymers, polyester resins, acrylic resins, xylene resins, polyamide resins, ionomer resins, silicone resins, guanamine resins, ketone resins, terpene resins, phenols Modified terpene resins, rosin, rosin-modified resins, maleic acid-modified phenolic resins, petroleum-based resins, starch graft polymers, polyvinyl alcohol, polyvinylpyrrolidone, and mixtures thereof, and inorganic ones such as silica (glass powder) and oxidized Examples include aluminum, zinc oxide, ultramarine and mixtures thereof.

Furthermore, in the toner of the present invention, in order to maintain good low-pressure fixing properties and sufficient blocking resistance, the coverage of small particles B (as a projected area on the surface of base particles A) is 40 to 40% of the surface area of base particles A. A range of 100% is preferable. If this coverage is less than 40%, the blocking resistance will be insufficient, and if it exceeds 100%, the small particles will not be sufficiently buried in the base particles during fixing, and the contact area between the base particles and the copy paper will not increase. As a result, fixing performance deteriorates.

The coverage α (xlOO%) of the small particles B is determined as follows. That is, the diameter (as an average particle size) and true specific gravity of the small particles B are d and ρ61. The diameter (as an average particle size) and true specific gravity of base particle A are kd and ρ6, respectively, and the weight of one base particle is W*.

Since the weight of /11 particles per one base particle is W small, the following holds true. Substituting equation (1) into equation (2), W6
Obtain ρ small 4. Here, when the particle size ratio k and true weight ratio ρ6/ρi of the base particle A and small particle B are known, the appropriate coverage α(X 100 %), it was found to be in the range of 40 to 100%. To make the toner of the present invention, appropriate amounts of base particles A and small particles B are mixed using a type blender, vibrating mill, etc. Mix and stir with a stirrer.

The toner of the present invention as described above can be used as a one-component dry developer by containing a magnetic material in the base particles A and/or small particles B, or as a two-component dry developer by mixing with a magnetic material. Ru.

The present invention will be explained below by way of examples. Note that all parts are parts by weight.

Example 1 Carbon black (#44; manufactured by Mitsubishi Chemical Corporation)
The ingredients consisting of 10 parts were kneaded using two hot rolls at a temperature of 130°C for 3 hours, cooled, and coarsely ground using a hammer mill, and then finely ground using a jet mill to obtain particles with a particle size of approximately 11.
A μm base particle was created.

On the other hand, small particles with a molecular weight of 300,000 and an average particle size of 0.5 μm were prepared by suspension polymerization of methyl methacrylate monomer using benzoyl peroxide as an initiator.

Next, 10 parts of base particles and 1.5 parts of small particles were mixed and heated to 50°C.
A toner with a surface coverage of 82.5% was obtained by kneading the mixture in a V-type blender for 3 hours while maintaining the temperature.

Next, in order to examine the blocking resistance of this toner, 10 g of the toner was placed in a glass bottle with an inner diameter of 25 rrel and a height of 70 mm.
g, put a load of 15 nmφ100 g on it,
After leaving it in a constant temperature bath at 50℃ for 24 hours, remove the load and JI
When the penetration (n,) was measured with a S-K2530 penetrometer, it was as high as 20 mm, indicating that it has blocking resistance.
Therefore, it was recognized that the storage stability was good.

Further, the above toner and silicone resin-coated ferrite particles (particle size 100 μm) as a carrier were mixed at 2.57100 μm.
A two-component developer was prepared by mixing at a weight ratio of . The toner charge amount of this product was good at -15 μC/g.

Next, apply this developer to a plain paper copying machine (Ricoh FT-406).
0 fixing unit part with metal roller 300kg/c
n? (modified to apply pressure to the copy paper), and when copies were made, clear copies were obtained. Furthermore, when the black solid area of this copy was rubbed with a crockmeter and the fixing rate (image density after rubbing with a crockmeter) was measured, it was found to be 85%, which is sufficient for practical use.

Furthermore, even after approximately 50,000 copies were continuously copied, no toner filming was observed on the photoreceptor, no image deterioration was observed, the toner charge amount was stable at -21 μc/g, and there was no toner scattering inside the machine. was also not recognized.

On the other hand, for comparison, when the base particles of this example were used as a toner and similarly evaluated, the toner charge amount when used as a developer was good at -21 μc/g, the copied image was clear, and the image was fixed. The rate was also good at 87%, but the blocking resistance (penetration), that is, the storage stability was poor at 0 mm.

After continuous copying of approximately 3,000 sheets, toner filming began to occur on the photoconductor, background stains appeared on the image, the toner charge amount decreased to approximately -8 μc/g, and the inside of the machine Toner scattering occurred.

Example 2 The components were subjected to cross-wire pulverization in the same manner as in Example 1 to prepare base particles having a particle size of about 10.5 μm.

On the other hand, (#44; manufactured by Mitsubishi Kasei Corporation) 10 components were similarly mixed by 600,000 yen at a temperature of 130°C using two heated rolls, then cooled, coarsely ground with a hammer mill, and then crushed with a jet mill. Finely grind to about 2.5μ
m small particles were created. 10 parts of base particles and 7.5 parts of small particles
A toner having a surface coverage of about 79% was prepared by mixing and agitating the two parts with a V-type blender at about 30°C.

The blocking resistance (penetration), or storage stability, of this product is good at 15 mm, the toner charge amount when used as a developer is good at -18 μc/g, the copied image is clear, and the image fixation rate is 88%. It was good.

In addition, even after approximately 50,000 copies were continuously copied, no toner filming was observed on the photoconductor, no image deterioration was observed, the toner charge amount was stable at -15 μc/g, and there was no toner scattering inside the machine. I was not able to admit.

Example 3 (Aerosil R-972) 30
Miyako terpene-phenol copolymer (ys polystar 82130: manufactured by Yasushi Oil Co., Ltd.) 3
Part 0 Phthalocyanine Blue
The components consisting of 5 parts were kneaded and pulverized in the same manner as in Example 1 to prepare base particles having a particle size of about 11 μm.

Below, 10 parts of base particles and 6.3 parts of glass powder with a particle size of about 1 μm as small particles are mixed, and mixed and stirred for 3 hours in a V-type blender while keeping the temperature at 50°C, to create a toner with a surface coverage of about 80%. It was created.

The blocking resistance (penetration), that is, the storage stability of this product is good at 25 mm, the toner charge amount when used as a developer is good at -15 μcog, the copied image is clear, and the image fixation rate is good at 88%. Met.

Furthermore, even after approximately 50,000 sheets were copied continuously, no toner filming was observed on the photoreceptor, no image deterioration was observed, the toner charge amount was stable at -16 μc/g, and there was no toner scattering inside the machine. Isao Issumi - As described above, the toner of the present invention has small particles with low pressure deformability embedded in the surface of large base particles with high pressure deformability, so it can be used under low pressure. It can be fixed, has anti-blocking properties, and therefore has good storage stability. It also has excellent durability as it does not cause filming on the photoreceptor or carrier, and maintains good charging performance even after repeated use. ing.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an example of the toner of the present invention.

Claims (1)

[Scope of Claims] 1. Small particles B, which are less susceptible to pressure deformation than the base particles A and have a smaller particle size, are placed on the surface of the base particle A, which has a larger pressure deformability and a larger particle size than the small particles B. A toner for developing an electrostatic latent image, which is embedded and coated at a depth less than the particle size of the small particles B. 2. A patent claim in which the surface coverage by the small particles B is in the range of 40 to 100% of the surface area of the base particles A, and the average particle size of the base particles A is 3 times or more the average particle size of the small particles B. The toner according to range 1.