JPS6230258A - True spherical electrophotographic toner - Google Patents

Abstract

PURPOSE:To improve mobility of a toner, its ability of jumping to the magnetic drum of a copying machine, and heat fixability to a paper and to obtain a sharp and stable image by forming a true spherical electrophotographic toner containing a specified amount of colorant and a specified amount of pigment, and the like, and a specified range of particle diameter. CONSTITUTION:The colorant C is melt mixed with 100pts.wt. of the sum of x pts.wt. of a binder component A and y pts.wt. of a component B incompatible with the component A (x+y=100) in an amount of 1-60pts.wt. at a temperature of not below the boiling points of A and B, and an A/B ratio is controlled so as to form B in a continuous phase and A in a dispersed phase. The molten mixture is directly cooled or after heat treatment within 2hr at such a temperature. The cooled mixture is immersed in a solvent S being a poor solvent for A and a good solvent for B to decompose the mixture, and a suspension of the particles of A incorporated C and suspended in a solution of S dissolving B is obtained, and these particles of A are used for the component of the toner. A styrene-acrylic type copolymer and the like are preferable for the binder component A.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a truly spherical electrophotographic toner.

[Conventional technology]

Conventionally, electrophotographic toner is produced by mechanically crushing its composition.
Heat treatment and the like were performed to classify the particles into particles of a predetermined size and to make them closer to a spherical shape. In addition, suspension polymerization method,
Methods such as emulsion polymerization in which binder monomer droplets containing colorants, magnetic pigments, etc. are polymerized while being dispersed in a solvent are also being considered.

[Problem that the invention seeks to solve]

However, the former method actually yields only particles that deviate greatly from a true sphere, and the yield is low due to the classification process. Even with the latter method, it is difficult to contain a predetermined amount of colorant, magnetic pigment, etc.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems of the prior art and to provide a truly spherical electrophotographic toner containing a predetermined amount of a colorant, a magnetic pigment, etc. and having a predetermined particle size.

[Means for solving problems]

The true spherical electrophotographic toner of the present invention is as follows.

That is, (1) "X parts by weight of binder component A, 1 part by weight of component B which is not compatible with A, 1 to 60 parts by weight of colorant C for x + y = 100 parts by weight, B By adjusting the ratio of X and y under the mixing ratio where A is a continuous phase and A is a dispersed phase,
and B are melted and mixed at a temperature above the melting temperature of A and B, and the molten mixture is cooled as it is or after heat treatment at a temperature above the melting temperature of A and B for within 2 hours. The molten mixture is immersed in solvent S, which is a good solvent, to disintegrate the molten mixture, and the suspension is obtained in solvent S in which B is dissolved.True spherical electrophotographic use 2 containing particles of A containing C as a component component-based toner, (2) X parts by weight of binder component A, 1 part by weight of component B that is incompatible with A, 1 to 60 parts by weight of colorant C for x+y=100 parts by weight, and magnetic Pigment concentration 10-1
20 parts by weight are melt-mixed at a temperature higher than the melting temperature of A and B by adjusting the ratio of X and y under a mixing ratio where B forms a continuous phase and A forms a dispersed phase, and the molten mixture is As is or A
After heat treatment at or above the melting temperature of and B for up to 2 hours, the molten mixture is cooled and immersed in a solvent S that is a poor solvent for A and a good solvent for B to disintegrate the molten mixture,
This is a spherical one-component toner for electrophotography, which consists of particles of A containing C and D in a suspension obtained in a solvent S in which C and D are dissolved.

In the present invention, the two-component toner for electrophotography is used by mixing with so-called carriers such as iron powder, ferrite spheres, aluminum powder, glass spheres, etc. This method is used for the electrofax method (EF method), electrostatic recording method (facsimile), etc.

Further, in the present invention, a one-component toner for electrophotography refers to a toner alone without a carrier that is used in PPC method, EF method, electrostatic recording method, etc.

In the present invention, colorants include cargin black, nigrosine-based basic dyes, acid dyes, organic pigments, and inorganic pigments.

In the present invention, magnetism and pigments include iron and cobalt.

2. Kel, manganese, magnesium, and their alloys and oxides.

In the present invention, the binder component A is a styrene-acrylic copolymer, a polyester type, a polypropylene type, a polyethylene type, or an epoxy type.

SBR type, polystyrene type, polyacrylic wax,
and copolymers and blends thereof are desirable, but other general thermoplastic resins can also be used.

Component B in the present invention forms a continuous phase in which the binder component A is dispersed to form microspheres.

Preferred examples of component B include the above-mentioned exemplary polymers of binder component A, as well as polyalkylene oxides such as polyethylene oxide, polyethylene glycol, polyvinyl alcohol, polymethyl methacrylate, polybutene, wax, natural rubber, synthetic rubber, etc. I-liptadiene, styrene-butadiene copolymer rubber, petroleum resin, etc. can also be used.

However, not all of the illustrated binder components A and B can be used in any combination;
and B must choose an incompatible combination.

A method for selecting incompatible combinations of A and B can be as follows. 30 volume parts of binder component A and 70 volume parts of component B are melt-mixed at a temperature higher than the melting temperature of A and B, the molten mixture is hot press-molded into a sheet with a thickness of 0.5 wn, and the poor solvent of A is When the sheet is immersed in solvent S, which is a good solvent for B, and stirred for 1 hour, and the sheet collapses to form a suspension, A and B are an incompatible combination.

When binder component A or component B dissolves in a solvent at the usage temperature to a concentration of 1 part by weight or more, the solvent is said to be a good solvent for A or B, and only dissolves at a concentration of less than 1 part by weight. , the solvent is said to be a poor solvent for A or B.

This dissolution test involves adding one weight of a film or powder sample with a thickness of about 0.5 mm to a solvent at a predetermined temperature.
After sufficient stirring for 2 hours, judgment can be made.

The mixing ratio in which B forms a continuous phase and A forms a dispersed phase is usually a mixing ratio in which B is 50 volume ratio or more and A is less than 50 volume ratio, but in detail, this mixing ratio may deviate. Yes, this can be determined as follows. That is, A and B, which are not compatible, are melt-mixed at a predetermined mixing ratio at a temperature higher than the melting temperature of A and B, and the molten mixture is hot press-molded to a thickness of 0.5.
When the sheet is immersed in solvent S, which is a poor solvent for A and a good solvent for B, and stirred for 1 hour, and the sheet collapses to form a suspension, the mixing ratio is such that B is a good solvent. It can be determined that the mixing ratio is such that A forms a dispersed phase in the continuous phase.

When melting and mixing A, B, and C, or A, B, C, and D, it is necessary to perform the melting at a temperature higher than the melting temperature of A and B. Otherwise, the structure of the mixture in which A becomes fine microspheres and is dispersed in phase B cannot be changed.

In the present invention, the method of melt-mixing is not particularly limited. The process can be carried out using a side light, a roll, a Banbury mixer, a kneader, a single screw extruder, a twin screw extruder, or the like.

A and B! :C, t or a molten mixture of A, B, C and D may be immersed in a solvent S which is a poor solvent for A and a good solvent for B after cooling. In this case, the molten mixture may be cooled and then crushed using a crusher or the like, pelletized using a pelletizer, or formed into a sheet using an extruder, roll, etc., and then immersed in the solvent S.

In addition, after heat-treating the molten mixture at a temperature higher than the melting temperature of A and B for less than 2 hours in a state where no shear deformation force is applied, the solvent S
It may be immersed in it.

In this case, during the heat treatment in the molten state, the human phase grows into a perfect spherical shape with a more beautiful shape, and the A phase coagulates with each other to grow into a true spherical shape with a large particle size.

Therefore, by controlling the heat treatment time, the particle size can be easily controlled.

The heat treatment method is not particularly limited. For example, if the molten mixture is made into a crusher-pulverized product, a pellet, a sheet, etc., A,! : Place in a constant temperature bath set at a predetermined temperature higher than the melting temperature of B and leave to stand for a predetermined time. In this case, it may be in air, but if the time is long, it may be in nitrogen gas or A.
Deterioration can be prevented by heat treatment in a poor solvent containing B and B.

In addition, heat treatment methods include extrusion molding, inflation molding, roll molding, etc. of the molten mixture of A and B! The molded product may be formed into a sheet or strand, and the time taken for the molded product to cool and solidify may be adjusted by controlling the cooling conditions or by heating. It should be noted that if the heat treatment time is 2 hours or more, deterioration will occur, which is not preferable.

When a molten mixture of A and B is immersed in solvent S and stirred, component B forming the continuous phase dissolves, causing the molten mixture to collapse and form microspheres of binder component A. A cloudy suspension is obtained.

The method for separating the microspheres of A from the suspension is as follows:
Not particularly limited. For example, it can be carried out by centrifugation, filtration, sedimentation, floating separation, evaporation, etc. At this time, it is desirable to wash with solvent S several times.

The shape and particle size of the microspheres of A thus obtained are as follows:
It can be observed and measured using a scanning electron microscope, transmission electron microscope, etc.

In the present invention, A, B and cl or A, B, C and D
When melt-mixing the two, if necessary, charge control agents (dyes, organic acid salts, surfactants, etc.), flow improvers (hydrophobic silica, graphite, molybdenum disulfide, etc.), and anti-blocking agents are added. By adding other additives (silicone resin, higher fatty acid ester, etc.), microspheres A containing the additives can also be produced.

Alternatively, A and C, or A, C, and D may be first melt-mixed, and the resulting molten mixture may be mechanically pulverized or pelletized, and then B may be melt-mixed with the resulting molten mixture.

〔Effect of the invention〕

According to the present invention, a perfectly spherical electrophotographic toner containing a predetermined amount of a colorant, a magnetic pigment, etc. and having a predetermined particle size can be obtained, and the toner has excellent mobility and flight to a magnetic drum of a copying machine. This has the effect of improving heat fixability to the paper surface and making it possible to obtain clear and stable images.

〔Example〕

Examples of the present invention are shown below.

(Example 1) The compounding recipe shown in Example 1 in Table 1 was kneaded in a kneader at 150 to 170°C for 10 minutes, and after cooling, the molten mixture was added to water at 30%. , stir for 2 hours to obtain a suspension.

This suspension was separated using a microfilter to obtain a perfectly spherical toner having a particle size of 1 to 10 μm.

This toner had a portion of a colorant dispersed in component A.

This toner was mixed with iron powder carrier EFV 250/400 at a toner content of 10% by weight, and Canon NP4
When copying was performed using 00RE, a clear image without fogging could be obtained.

(Example 2) After tri-blending the component A shown in Example 2 in Table 1, the colorant C, and the charge control agent, it was heated in a kneader, and the mixture was heated to 160-1
After kneading at 90° C. for 20 minutes, the molten mixture was cooled and then pulverized using a crusher.

Next, mix this pulverized material and component B in a kneader.
The mixture was kneaded at 60 to 180°C for 10 minutes, and after cooling, the molten mixture was immersed in water and stirred for 30 minutes to obtain a suspension.

This suspension was centrifuged to obtain particles with a particle size of 10-20□μ.
A perfectly spherical toner of m was obtained. In this toner, component A contains
Colorant C and a charge control agent were dispersed therein.

This toner was mixed with iron powder carrier EFV 250/400 at a toner content of 15% by weight, and the copying machine NP-55
00 machine and when copying was performed, clear images without fog could be obtained.

In addition, stable and good images were obtained even after continuous image printing of 100,000 sheets.

(Example 3) After tri-blending the component A, colorant C, and fluidizing agent shown in Example 3 in Table 1,
After kneading at 200° C. for 20 minutes, the molten mixture was cooled and pulverized using a crusher.

Next, this pulverized material and component B are put into a kneader,
The mixture was kneaded at 30 to 250°C for 5 minutes, and after the melt-mixing was completed, the rotation of the rotor was stopped and a static heat treatment was performed in a kneader for 5 minutes to complete the spherical component and grow the grains. .

After cooling, the molten mixture was added 10% to acetone at room temperature and stirred for 2 hours to obtain a suspension.

This suspension was centrifuged to obtain particles with a particle size of 2° to 30μ.
A perfectly spherical toner of m was obtained. In this toner, component A contains
Colorant C and a fluidizing agent were dispersed therein.

This toner was mixed with iron powder carrier EFV 250/400 at a toner content of 10% by weight, and the copying machine NP-5
When copying was performed using 500 machines, clear images with no fog could be obtained. In addition, stable and good images were obtained even after continuous image printing of 100,000 sheets.

(Example 4) Component A shown in Example 4 in Table 1, colorant C, magnetic pigment, and cleaning agent were triblended, and then kneaded in a kneader at 160 to 180°C for 10 minutes. After cooling, the resulting molten mixture was crushed using a crusher.

Next, this pulverized material and component B were mixed in a kneader,
The molten mixture was kneaded at 0 to 180°C for 10 minutes, and after cooling, 20% by weight of water was added and stirred for 1 hour to form a suspension.

This suspension was centrifuged to obtain particles with a particle size of 1o to 20μ.
A perfectly spherical toner of m was obtained. In this toner, component A contains
Colorant C, magnetic pigment, and cleaning agent were dispersed therein.

When this toner was applied to a copying machine (Xerox 4370) and copied, a clear image without fogging could be obtained. In addition, stable and good images were obtained even after continuous image printing of 100,000 sheets.

Claims (2)

[Claims] (1) x parts by weight of binder component A, y parts by weight of component B that is not compatible with A, 1 to 60 parts by weight of colorant C for x + y = 100 parts by weight, and B is a continuous phase. Under the mixing ratio at which A forms a dispersed phase, adjust the ratio of x and y,
A and B are melted and mixed at a temperature higher than the melting temperature of A and B, and the molten mixture is heated as it is or after being heat treated at a temperature higher than the melting temperature of A and B for up to 2 hours, cooled, and the molten mixture is mixed with a poor solvent of A and The molten mixture is immersed in a solvent S, which is a good solvent for B, to disintegrate the molten mixture, and the suspension obtained in the solvent S in which B is dissolved contains true spherical particles of A containing C as a component. Ingredient toner. (2) x parts by weight of binder component A, y parts by weight of component B that is not compatible with A, 1 to 60 parts by weight of colorant C, and 10 parts by weight of colorant C for x + y = 100 parts by weight. ~12
0 parts by weight are melt-mixed at a temperature equal to or higher than the melting temperature of A and B by adjusting the ratio of x and y under a mixing ratio in which B forms a continuous phase and A forms a dispersed phase, and the molten mixture is Either as it is or after heat treatment for up to 2 hours at a temperature above the melting temperature of A and B, the molten mixture is cooled, and the molten mixture is immersed in a solvent S that is a poor solvent for A and a good solvent for B. C and D in the suspension obtained in the solvent S in which B is dissolved
A true spherical one-component toner for electrophotography, which contains particles of A containing.