JPS63243963A - Electrostatic charge image developing powder toner and its manufacture - Google Patents

Abstract

PURPOSE:To smooth the surface of the toner and to eliminate too fine particles by coating fine resin particles specified in particle diameter with a hydrophobic resin and exerting mechanical stress to melt the surfaces of the agglomerated particles. CONSTITUTION:The fine spherical resin particles (A) of <=10mu average particle diameter are coated with the hydrophobic resin (B) and agglomerated, and the surfaces of the agglomerates are heat melted by mechanical stress and smoothed, and the colorant and other necessary fine particles are contained in said the fine particles A or said resin B. This toner is prepared by producing the fine particles A by the emulsion polymerization method or the suspension polymerization method, when needed, attaching the colorant and the like to the surfaces of them, coating them with the resin B, thus forming the agglomerates of the toner particles, then, disintegrating the agglomerates and classifying them, applying the prescribed mechanical stress to heat melt the resin B, thus smoothing the surfaces of the agglomerates and eliminating the fine particles, and rendering them resistant to crushing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a powder toner for dry developing electrostatic latent images in electrophotography, ion flow recording, etc.

(Prior Art) As a method for producing powder toner for dry developing electrostatic images, dyes, pigments, magnetic powder, etc. are dispersed in toner resin by melt mixing, and then mechanically pulverized.

A common method is to obtain it by classification.

However, the toner obtained by this method has an amorphous shape, and it is difficult to obtain a uniform charge.

Furthermore, the consumption of electrical energy required for melting, kneading and pulverization is enormous, and various methods have been proposed for producing toner by methods other than so-called pulverization.

As methods other than the above-mentioned pulverization method, spray drying method, emulsion polymerization method, interfacial polymerization method, suspension polymerization method, etc. are known.

However, since the spray drying method generates a single spherical toner, uniform charge is exchanged and the fluidity is good, but on the other hand, it requires explosion-proof measures and solvent recovery, and the thermal energy required for drying is enormous. There are drawbacks such as the fact that the solvent remains in the toner after drying and is difficult to remove.

For example, JP-A-36-10231.47-5183
Various methods have been studied for producing spherical toner particles in water using the suspension polymerization method disclosed in various publications such as No. 0.51-14895. This method makes it easy to obtain particles with a particle size suitable for toners, colorants, and waxes. It is easy to contain necessary ingredients for toner such as magnetic powder. However, dispersants of toner particles in water.

The stabilizer remains on the toner surface and is difficult to remove, and this stabilizer adsorbs moisture in the air, reducing the electrical resistance of the toner. Such toner has the disadvantage that V-sheet copying is difficult and the surface charge is non-uniform. Furthermore, in place of the suspension polymerization method,
It is also possible to use the emulsion polymerization method shown in various publications such as -50962.59-152459, but this method generally makes it easy to adjust the molecular weight distribution, which affects fixing properties, etc. However, on the other hand, the particle size of the particles produced However, they are too small as toner particles.

Another problem is that it is difficult to contain other toner components inside. Also, similar to the suspension polymerization method, a decrease in electrical resistance due to adsorption of moisture in the air is also a problem.

As mentioned above, each method for powder toner has its advantages and disadvantages, but the common problem is that when adjusting the particle size distribution to a range that can be passed as a toner, there are many particles that cannot be used, especially on the fine particle side. Depart. These materials are mixed into raw materials again for reuse, but those obtained by breast polymerization, suspension polymerization, etc. cannot be reused.

For example, there is one method of using a toner material that has been made fine in advance and aggregating it to granulate the toner.

Japanese Patent Publication No. 46-185.60-220358.61-16
It is described in various publications such as No. 7956.61-167957. However, this method has so far had the following problems and has not been fully put into practical use.

(2) Part of the finely divided toner material forms a secondary agglomerate, which is difficult to break up, so that the composition of the toner particles is not uniform.

(2) The granulated material has a highly uneven surface, becomes porous, has poor fluidity as an FA body, and is bulky, so that triboelectric charging does not occur uniformly.

■Because the cohesive force is weak, toner particles are destroyed by a relatively weak impact.

(Problems to be Solved by the Invention) In light of the above-mentioned current situation, the inventors of the present invention have conducted intensive studies and found that, in place of the conventional toner manufacturing method, which was extremely complicated and energy-consuming, all toner constituent components were made into fine particles. as particles,
This is coated with a resin and agglomerated using the coating resin as a binder. After that, a desired particle size distribution is obtained in a crushing process, and the shape is also adjusted. By doing so, it has excellent functionality as a toner, and simplifies the manufacturing process. We have discovered a method for producing powder toner that reduces energy consumption.

[Structure of the invention]

(Means for Solving the Problems) That is, the first invention of the present application essentially consists of: (1) spherical resin fine particles (A
), either the coating or the resin fine particles (A) contains a coloring agent and other necessary fine particles, and the surface of the aggregate is heated to melt the powder toner. A powder toner for developing an electrostatic image, characterized in that it is shaped into a preferable shape, and the second invention of the present application is a powder toner having an average particle size of 10 μm or less, containing a colorant and other necessary fine particles as necessary. The spherical resin fine particles (A) are coated with a hydrophobic resin together with a colorant or other necessary fine particles as the case may be, and then the coated fine particles are agglomerated, and the aggregate contains a plurality of spherical resin fine particles (A). Production of a powder toner for electrostatic image development, in which the hydrophobic resin is crushed into aggregates, and the surface of the aggregate is formed into a shape suitable for a powder toner by thermally melting the hydrophobic resin by mechanical strain during crushing. It's a method.

The present invention will be explained more specifically.

■ Add a coloring agent and other necessary fine particles as necessary to an aqueous dispersion of spherical resin fine particles (A) obtained by emulsion polymerization method or suspension polymerization method, etc., and homogenize.

Other fine particles are uniformly adhered to the surface of the resin fine particles (A) by applying strong shearing force using a colloid mill or the like. Here, other fine particles include dyes.

These include pigments, charge control agents, waxes, magnetic powder particles, etc.

At this time, the agglomerations of the resin fine particles (A) are also broken up. (
When fine particles other than the resin fine particles (A) are not used, the main purpose of the above operation is to crush the resin fine particles (A). ) ■Next, replace water with solvent. Or a spray dryer.

After drying with a vacuum dryer etc., immerse in a solvent.

Thereafter, it is coated with a hydrophobic resin by a coacervation method and dried using a spray dryer, a vacuum dryer, etc. to obtain an aggregate of toner raw materials.

(2) The toner raw material aggregate is a brittle mass in which fine resin particles (A) are coated with a hydrophobic resin. For this reason, it is easily crushed by a relatively light impact force, but normal crushing results in very broad particles with a particle size distribution ranging from fine powder to quite coarse particles.
The shape is porous and has many irregularities.

Therefore, in the present invention, in addition to impact type grinders such as hammer mills, rotary grinders such as coffee mills,
After using a crusher such as a rotary crusher or a cone crusher to obtain a mode diameter of about 10 to 25 μm with a volume-based particle size distribution, 1. For example, particles with a size of 25 μ or more are substantially removed by air classification, etc., and 5 volume-based particles are The median diameter (hereinafter referred to as average particle diameter) is adjusted to 5 to 15μ.

■The toner particles at this stage still maintain a porous shape with many irregularities, and the particle size is 5μ, which is inappropriate for toner.
A large number of the following particles are included. Next, by applying a mechanical strain force to the particles under conditions such that the average particle size of the particles is in the range of 8 to 20 μm by applying a rather strong impact force to the particles, substantially no fine particles are present.

Toner particles with smooth surfaces can be obtained. The number of fine resin particles (A) contained in each toner particle ranges from a few to several hundred.

Incidentally, as long as the above-mentioned processing conditions are understood, there is no problem even if the toner surface is smoothed and the fine particles are removed in advance, and then the coarse particles are removed.

The reason why the application of mechanical strain to toner particles produces the effect of smoothing the toner surface and removing fine particles is considered to be as follows. The toner particles collide with each other or with a dispersion medium such as two wall blades, and instantaneously and locally become quite high in temperature.

The surface of the toner appears to be in a thermally fused state. At this time, since fine particles tend to aggregate, the fine particles usually adhere to each other or to the surface of the particles, and the heat generated by the impact force softens the resin and fuses it together, resulting in the above effect. This can be understood by observing the electron micrographs before and after the above treatment. Namely.

Before processing, toner particles with relatively large particle sizes and porous particles are mixed, and some fine toner particles are aggregated on the surface of large toner particles. After processing, the toner surface becomes smooth and the toner particles are mixed. Almost no particles are seen.

Furthermore, the particles are difficult to break even during a running test inside a copying machine. This is how this method works.

A major feature of this method is that it can be processed continuously at room temperature without requiring special heating of the machine.

There are various factors that can be considered to achieve the above effects, but according to research by the present inventors.

The greatest effect is on the speed of the toner particles in the crusher.

Specifically, in hammer mills, coffee mills, etc., the rotation speed of the internal rotary plate is from several tens of revolutions/second to several hundred revolutions/second, and in other cases, it is desirable that the air flow velocity be approximately the same as above. Furthermore, at the same rotational speed (or airflow speed), the longer the residence time of particles within the machine, the greater the effect, so if necessary, the crusher may be recycled as a closed circuit.

In the present invention, the average particle size of the toner is in the range of several microns to 20 microns, and since the fine particles are sized, no special classification is required. In addition to the resin as a binder, the toner may optionally contain fine particles having an average particle size of 2 μm or less, such as a coloring material, magnetic powder, wax, and a charge control material. These fine particles may be aggregated together with the resin fine particles (A) or may be contained in the resin fine particles (A) in advance.

Resins that can be used for the resin fine particles (A) of the present invention include those having the function of holding a colorant, magnetic powder, etc. and fixing a visible image on one paper surface, such as ethylene-vinyl acetate copolymer, polystyrene-based resins, etc. , styrene-containing copolymers of styrene and acrylic esters or methacrylic esters, acrylonitrile or maleic esters, polyacrylic ester-based, polymethacrylic ester-based, polyester-based, polyamide-based, polyvinyl acetate-based, epoxy-based Examples include phenolic, hydrocarbon, and petroleum-based resins, and these can be used alone or in combination.

In the coacervation method that can be preferably used for coating the resin particles (A) with a hydrophobic resin in the present invention, first, the hydrophobic resin is dissolved in a good solvent, and then the hydrophobic resin particles (A) are added to this solution. Disperse.

A nonsolvent or a phase separation agent for the hydrophobic resin is added to this dispersion to cause phase separation and coat the surface of the resin fine particles (A). Examples of combinations of hydrophobic resin/good solvent/non-solvent (phase-separated organic agent) include 2.

polyvinyl acetate/methyl ethyl ketone/n-hexane,
Polyvinyl acetate/chloroform/isopropanol, styrene-maleic acid copolymer/ethanol/isopropyl ether, polyethylene/xylene/ethanol, polystyrene/benzene/polydimethylsiloxane, polystyrene/xylene/petroleum ether, ketone resin/ethanol/water , polymethyl methacrylate/Hensen/polydimethylsiloxane, acrylonitrile-styrene copolymer/methyl ethyl ketone/polybutadiene, epoxy resin/toluene/polybutadiene, polystyrene/benzene/poly p-chlorostyrene, and the like.

The coloring materials include dyes and pigments, and although they are not necessarily limited to these, nine examples include the following.

Yellow pigment/dye zinc yellow, yellow iron oxide, Hansa Yellow, Disazo Yellow,
Quinoline yellow, permanent yellow.

red pigment/dye Red Garla, Permanent Red, Lysole Renoto.

Pyrazolone Red, Wochanresodo Ca salt.

Wosochan Resodo Mn Salt, Lake Red C,
Lake Red D, Brilliant Carmine 6B, Brilliant Carmine 3B.

Blue pigment/dye Navy blue, phthalocyanine blue, metal-free phthalocyanine.

In addition, if necessary, colored pigments such as orange, purple, and green, titanium oxide, and white colors such as oil blanks.

Black pigments or dyes can be used.

Magnetic powders include various types of ferrite, magnetite, hematite, etc., including iron, zinc, cobalt, and nickel.

An alloy or compound such as manganese can be used, but its magnetic properties include a saturation magnetization of 70 e mu / g or more under a magnetic field of 5 kOe, and a coercive force of 2.
000e or less is particularly preferred. These magnetic powders are crystalline (cubic, octahedral, acicular, etc.), irregularly spherical,
All shapes such as rice grains can be used. Further, depending on the purpose, the material may be classified or may be subjected to surface treatment known per se, such as hydrophobic treatment or silane coupling agent treatment.

Waxes include polyolefin waxes such as polyethylene wax and polypropylene wax.

Petroleum waxes such as paraffin wax and microcrystalline wax, carnauba wax, and Senkun wax. There are natural waxes such as rice wax.

Charge control agents include Fetschwarz HBN, Nigrosine Base, and Brilliant Spirit.

Zaponsupalun X, Ceresupalun RG,!
There are dye 1 alloy dyes such as the same phthalocyanine dye, and others C01, Solvent Black 1, 2, 3, 5, 7°C, 1, Acid Black 123, 22, 23, 8, 4
2.43. Oil black (C, 1,6150), dyes such as Spiron black, quaternary ammonium salts.

Examples include naphthenic acid metal salts, fatty acid or resin acid metal soaps, and colloidal silica.

The present invention will be explained in detail below with reference to Examples. The middle part of the example shows parts by weight.

Example 1 A separable flask equipped with a stirrer, thermometer, condenser, dropping funnel, and gas introduction tube was heated to 80°C in advance.
, 0% polyvinyl alcohol (Nippon Gosei Chemical ■Product name G
H-20) Add 1,500 g of an aqueous solution and a liquid material pre-mixed according to the following recipe, and mix at 110,000 rpm for 10 minutes using a volume 31 Ultra Homo Mixer (manufactured by Nippon Seiki UL).
Stir for a minute.

Styrene 240g Methyl methacrylate 60g Benzoyl peroxide 60% xylene solution 12g After stopping the stirring, the emulsion was stirred at low speed at 90°C for 7 hours while purging with nitrogen to continue the double polymerization reaction.

Spherical fine resin particles with an average particle size of 8 μm were obtained. This is referred to as resin fine particles (AI). Next, the resin fine particles (A1) were once filtered, and the resulting cake was poured into n-hexane, water was replaced with n-hexane, and then filtered again.

Next, the ingredients are weighed and premixed according to the following recipe.

100 g of this mixture was poured into 300 g of a 10% ethyl alcohol solution of a ketone resin (trade name: Hilac 110H, manufactured by Hitachi Chemical! 11) and stirred for 5 minutes using a TK homomixer (manufactured by Tokushu Kika ■).

Resin fine particles (AI) 60 parts Triiron tetroxide powder (particle size 0.3μ) 40 parts Polypropylene wax (trade name: Viscol 550P, Sanyo Chemical Industries (manufactured by Ikiku) 2 parts Charge control agent (
Product name: Spiron Black TRH.

0.5 parts of carbon black (trade name: Mogul-L, manufactured by Cabosoto, USA) 1 part of carbon black (trade name: Mogul-L, manufactured by Cabosoto, USA)
100 g of hexane was gradually added over 5 minutes. This operation yielded an aggregate coated with ketone resin. From this, the solvent was filtered off and dried.

Next, this was introduced into a hammer mill (Sample Mill, manufactured by Hosokawa Micron (manufactured by 4-to-1)) and processed at high speed rotation.

The product discharged to the collector was treated in the same manner a total of 8 times to obtain toner particles having the desired average particle size of 13 μm. This contained substantially no particles with a size of 5μ or less, and almost no particles with a size of 25μ or more. Also, the electron microscope'RXt! According to visual observation using i, the surface was smooth and had a rounded shape. This was subjected to 1 classification treatment to completely remove particles larger than 25μ, and then the toner 1
0.3 parts of colloidal silica (trade name, R
-972, manufactured by Nippon Aerosil 91) was added and set in a commercially available copying machine (trade name: NP-3002, manufactured by Canon (manufactured by 11)).

In this copy, charge stability, blocking resistance, and image quality were extremely good.

Comparative Example 1 A sample that had been subjected to the sample mill treatment only once in Example 1 was taken out. Visual observation using an electron microscope shows that this is a porous surface with many irregularities.

Furthermore, many fine powders of 5μ or less were also observed. When colloidal silica was added to this as in Example 1 and a copying test was conducted, blocking occurred in the toner hopper and the image density was extremely low and unsuitable.

Example 2 Using a pressurized reactor with a volume of 101 cm, a polymerization reaction was carried out according to the following recipe by an emulsion polymerization method while maintaining the temperature at 20° C. while purging with nitrogen.

Styrene 80 parts Butyl methacrylate 20 parts Divinylbenzene 0.2 parts This was dispersed in 200 parts of water. Furthermore, 2 parts of fatty acid potassium salt and 0.5 part of potassium phosphate were used as emulsifiers. 24 hours,
The polymerization reaction was continued with low speed stirring to obtain a latex with an average particle size of 0.8 μm. This is referred to as resin fine particles (A2). Hereinafter, n-hexane substitution was carried out in the same manner as in Example 1, and a mixture of the following formulation was used.

The same coating treatment as in Example 1 was performed.

Fine resin particles (A2) 60 parts Triiron tetroxide powder (particle size 0.3μ) 40 parts Polypropylene wax (trade name: Viscol 550P, manufactured by Sanyo Chemical Industries, Ltd.) 2 parts Charge control agent (trade name: Spiron Black TRH).

Hodogaya Chemical Industry Co., Ltd.) 0.5 parts Carbon blank (trade name: HMogul-L, manufactured by Cabot, USA) 1 part The obtained aggregates were first crushed in a sample mill.

Continuing with the circulation type impact crusher (product name type NH3-
1; Introduced 150g into Nara Machinery Craft) and 6000rp.
m for 2 minutes. The average particle size thus obtained was 12μ.
When the toner was subjected to the same treatment as in Example 1 and a two-image test was conducted, no blocking occurred and good images could be obtained.

〔Effect of the invention〕

The electrostatic toner according to the present invention consumes less energy in production than conventional toners, and through the post-processing according to the present invention, toner particles having a desired particle size can be efficiently obtained, and the particle shape of the toner can be improved. It becomes possible to improve.

Claims (1)

[Claims] 1. Essentially an average particle size of 10 with a coating of hydrophobic resin.
It is an aggregate of a plurality of spherical resin fine particles (A) of μ or less in size, and either the coating or the resin fine particles (A) contains a coloring agent and other necessary fine particles, and the surface of the aggregate is is a powder toner for developing an electrostatic image, characterized in that it is formed into a preferable shape as a powder toner by thermal melting. 2. The powder toner for developing electrostatic images according to claim 1, wherein the spherical resin fine particles (A) are produced by an emulsion polymerization method or a suspension polymerization method. 3. Spherical resin fine particles (A) with an average particle size of 10 μm or less, containing a colorant or other necessary fine particles as necessary, are coated with a hydrophobic resin, and then coated with a hydrophobic resin. The coated fine particles are agglomerated, the agglomerates are crushed into aggregates containing a plurality of spherical resin fine particles (A), and the hydrophobic resin is thermally melted by the mechanical strain at the time of crushing to form a powder toner. A method for producing a powder toner for developing an electrostatic image, which comprises shaping the surface of the aggregate into a preferred shape. 4. The method for producing a powder toner for developing electrostatic images according to claim 3, wherein the spherical resin fine particles (A) are produced by an emulsion polymerization method or a suspension polymerization method. 5. Electrostatic image development according to claim 3, wherein the surface of the spherical resin particles (A) is coated with a hydrophobic resin by a coacervation method in an organic solvent that does not dissolve or swell the spherical resin particles (A). A method for producing powder toner for use.