JPS5840735B2 - Denshishashinyoukanshikigenzozai - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dry developer for electrophotography, and more particularly to a magnetic microcapsule toner that can be fixed by pressure.

The development methods for dry electrophotography are generally the cascade method,
Magnetic blurring etc. are used.

In both of these methods, carrier particles such as glass beads or iron powder are mixed with toner particles to form a developer, the toner particles are charged by frictional charging, and this is brought into contact with an electrostatic latent image to visualize it. However, toner particles (finely pulverized thermoplastic resin with colorant uniformly dispersed in them) further become pulverized during frictional charging with carrier particles, causing contamination inside and outside the copying machine due to scattering of toner particles. At the same time, this also causes deterioration of carrier particles and deterioration of image quality, forcing early replacement of the developer.

Furthermore, in order to fix powder images obtained with these toners, it is necessary to heat and melt the toner, and to do so, it is necessary to raise the temperature of the fixing device to the softening point of the toner. This has drawbacks such as being worn for a long time and consuming a considerable amount of power to maintain the temperature at a predetermined temperature.

On the other hand, in order to omit the mixing step of toner particles and carrier particles, in recent years a method of developing with a magnetic roller (Japanese Unexamined Patent Application Publication No. 49/1989) has been developed.
No. 4532, etc.) have been developed, and developers for this system are also being studied.

This type of developer consists of toner, each of which contains its own carrier.

In addition, the fixing method after development is becoming simpler, and the conventional high-energy heat fixing method is being replaced by a low-energy pressure fixing method. are also commercially available.

The pressure fixing magnetic developer used in such copying machines has magnetic properties that allow it to easily adhere to the roller surface due to the magnetic field of the magnetic roller, and electrostatic properties that resist magnetic force due to its own charge or electric field. It is necessary to have electrical properties that allow the latent image to be easily attracted, properties as a carrier particle, and other properties such as sufficient fluidity and pressure fixing properties that allow fixing at as low a pressure as possible.

However, it is extremely difficult to obtain a toner that satisfies all of these requirements.
The pressure-fixable magnetic toner described in the above issue has poor fluidity, so a fluidity improver such as hydrophobic silica is added, but as a result, the toner's fixability is inhibited and the pressure required for fixing is reduced. The amount is extremely large at 300 to 400 pounds/(inch)2, and it cannot be called a completed product in practical terms.

The present invention eliminates the above-mentioned drawbacks and provides a practical pressure-fixable magnetic toner that has excellent fluidity and can be fixed at low pressure.

That is, the present invention has a pressure-adhesive soft solid as a core material,
A first wall mainly made of a film-forming polymer material and a second wall mainly made of synthetic resin are provided on the outside of the core material, and at least one of the core material, the first wall, and the second wall is made of a magnetic material. An object of the present invention is to provide a dry developer for electrophotography, which contains a powder and a colorant, and further contains a water-soluble or water-dispersible silicone in the second wall.

By containing water-dispersible or water-soluble silicone in the outermost wall of the double capsule wall, the developer of the present invention has a narrower particle size distribution and better fluidity than conventional developer.

One basic method for manufacturing such a developer is to emulsify and disperse a non-aqueous solution or aqueous dispersion of a pressure-adhesive soft solid in an aqueous solution of a film-forming polymeric substance, and use the dispersed particles as a core material. After encapsulation in water, this encapsulation liquid is mixed with a synthetic resin emulsion and a water-soluble or water-dispersible silicone to form a capsule slurry, which is then spray-dried to perform double encapsulation.

In this case, the magnetic powder and the coloring agent may be contained in at least one of the core material, the first wall, and the second wall.

As a method for encapsulating the core substance, known microencapsulation methods such as complex coacervation method, simple coacervation method, salt coacervation method, aqueous solution or insolubilization of polymer by pH change, solvent change, and solvent removal can be used. Phase separation method from aqueous dispersion,
Any method that can encapsulate a hydrophobic substance in an aqueous medium, such as interfacial polymerization method or In5itu polymerization method, can be used.

Example The encapsulation method and developer manufacturing method using the Eva complex coacervation method are as follows.

A non-aqueous solution or aqueous dispersion of a soft solid is added to an aqueous solution of a film-forming polymeric substance (for example, gum arabic) adjusted to a predetermined pH (alkaline side), concentration, and temperature, and then dispersed and emulsified. An aqueous solution of a film-forming polymeric material (eg gelatin), which is a gelatinable isoelectric colloid, is added to the temperature adjusted solution.

Next, H in this mixed solution is made acidic to cause phase separation.

In this way, the polymer substance is precipitated around the droplets of the soft solid non-aqueous solution or aqueous dispersion, and then the liquid is cooled,
A hardening agent (formalin) is added to make the solution alkaline and the temperature of the solution is raised to harden the precipitate.

A colorant, magnetic particles, a synthetic resin emulsion, and a water-soluble or water-dispersible silicone are added to the obtained capsule liquid, uniformly dispersed, and then spray-dried.

In this case, a toner containing a colorant and magnetic particles in the second wall is obtained.

In the toner of the present invention, the appropriate amount of the soft solid used is about 0.5 to 15 parts by weight, preferably about 3 to 10 parts by weight, in terms of solid content per 1 part by weight of the film-forming polymeric substance.

The amounts of magnetic particles, colorant, synthetic resin, and silicone used are 20 to 70% by weight (preferably 40 to 60% by weight), 0 to 10% by weight, 1 to 60% by weight, and 0.0001 to 0.0001% by weight, respectively, based on the total amount of the toner. Approximately 5% by weight is appropriate.

The soft solid has adhesive properties under pressure, acts as a fixing agent, and serves as the core material of the microcapsule toner of the present invention.

Examples of such soft solids include higher fatty acids such as stearic acid, palmitic acid, myristic acid, lauric acid, and capric acid; higher fatty acid metal salts such as aluminum, lead, barium, magnesium, or zinc salts of stearic acid; and zinc palmitate; Higher fatty acid derivatives such as hydrogenated castor oil, cocoa butter, methyl hydroxystearate, glycerol monohydroxystearate, higher fatty acid amides such as octadecaneamide, hexadecaneamide, tetradecanamide, dodecanamide, decanamide, octanamide, hexaneamide, etc. , beeswax, carnauba wax, microcrystalline wax, 7 grade waxes, rosin,
Condensation of rosin derivatives such as hydrogenated rosin and rosin ester, alkyd resins such as drying oil or semi-drying oil type alkyd, epoxy-modified phenolic resin, natural resin-modified phenolic resin, amine resin, silicone resin, polyurethane, urea resin, polyester, etc. -based polymers, copolymerized oligomers of acrylic acid or methacrylic acid and long-chain alkyl methacrylates or long-chain alkyl acrylates, copolymerized oligomers of styrene and long-chain alkyl acrylates or long-chain alkyl methacrylates, polyolefins such as polyethylene, ethylene-based polymers, etc. Examples include vinyl acetate copolymers, ethylene rubinyl alkyl ether copolymers, maleic anhydride copolymers, petroleum residues such as asphalt and giltnite, and rubbers such as imbutylene rubber, nitrile rubber, and chlorinated rubber. .

Note that when a resin is used as the soft solid, one with a low molecular weight is suitable.

Film-forming polymeric substances forming the first wall include gum arabic, gelatin, albumin, sodium alginate, carboxymethyl cellulose, hydroxyethyl cellulose, ethylene-sodium maleic anhydride copolymer, polyvinylmethylniteryl maleic anhydride (or its ester) copolymers, styrene acrylic acid-butyl methacrylate copolymers, etc.

The synthetic resin forming the second wall is polycarbonate,
Polyester, polyamide, polyether, polyolefin, polystyrene, styrene acrylate copolymer, styrene-methacrylate copolymer, styrene-ethylenically unsaturated monoolefin copolymer, styrene rubinyl ester copolymer, styrene rubinyl ether copolymer Coalescence, styrene-acrylonitrile copolymer, styrene ~
Methacrylonitrile copolymer, styrene acrylamide copolymer, styrene-α-methylene fatty acid monocarboxylic acid ester copolymer, styrene to vinylidene halide copolymer, polyvinyl acetate, or two or three of these
Copolymers or mixtures of these polymers are used in the form of aqueous dispersions.

Coloring agents include carbon black, nigrosine dye, aniline blue, calco oil blue, chrome yellow, cream clean, ultramarine blue, cobalt flu, typhon oil, benzidine yellow,
These include quinoline yellow, methylene blue chloride, phthalocyanine blue or green, malachite green oxalate, lamp black, rose bengal and mixtures thereof.

Magnetic materials (including those that can be magnetized) include cobalt,
Metals like iron, nickel; aluminum, cobalt,
copper, iron, lead, magnesium, nickel, tin, zinc, gold,
silver, antimony, beryllium, bismuth, cadmium,
Alloys or mixtures of metals such as calcium, manganese, selenium, titanium, tungsten, vanadium, zirconium; metal oxides such as aluminum oxide, iron oxide, copper oxide, nickel oxide, zinc oxide, zirconium oxide, titanium oxide and magnesium oxide refractory nitrides such as chromium nitride; carbides such as tungsten carbide and silica carbide; ferromagnetic ferrites and mixtures thereof.

Water-soluble or water-dispersible silicone has antifoaming effect, slipping effect,
It has a dispersing effect and also has the effect of lowering the viscosity of the liquid, so it not only improves the dispersion of magnetic particles and colorants during toner preparation and improves workability, but also enables particles with uniform diameter and well-shaped shape. A toner with good fluidity can be obtained.

Moreover, unlike conventional fluidity improvers such as silica, such silicone has the feature that it has almost no effect on pressure fixing properties within the above-mentioned addition amount range.

As the water-soluble silicone, we use silicone oil, which is a linear polymer substance with -8i -08i- siloxane bonds as its backbone, that is, a compound represented by the general formula (R is hydrogen, an alkyl group, or an alkyl group) to make it hydrophilic. Examples include silicone-glycol copolymers and polyether-modified silicone oils.

The water-dispersible silicone is made by emulsifying silicone oil with water (and a surfactant), and a low-viscosity silicone with little stickiness is particularly preferred.

Commercially available products include Toray Silicone 5H28, 5H3746,
SH3747, 5H3748, 5H3749, 5H37
71 (manufactured by Toshi), Shin-Etsu Silicone KF-351, KF-
353, KF-610゜KF-352, KF-611, etc. (water-soluble silicones made by Shin-Etsu Chemical), Shin-Etsu Silicone KM681F, KM68-2F, Kt-70, KM-7
2, KM-72A, KM-73, KM-74, KM-7
5, KM-82, KM-83, KM-84, KM-85
(water-dispersible silicone manufactured by Shin-Etsu Chemical Co., Ltd.), Lehle Silicone 5H Fu036 (water-dispersible silicone manufactured by Toshi Chemical Industry Co., Ltd.), and the like.

Examples are shown below.

Example 1 After adjusting the pH to 10 with lN-NaOH, solid content 1002 of wax emulsion (Central Oil ■Cellosol #967) was added as a core material to 5% aqueous solution 1001 of acid-treated gelatin (isoelectric point 8.8) at 40°C. plus 550 rpm
Stir with a three-one motor.

To this was added a 5% aqueous solution 1002 of gum arabic (isoelectric point 8.7) at 40°C adjusted to pH 10 with 1N-NaOH and stirred for 10 minutes, then a 5% acetic acid aqueous solution was gradually added dropwise for 1 hour. The pH was lowered to 4.4 over a period of time to cause phase separation, and a gelatin-gum arabic film containing wax was precipitated.

After stirring for another 10 minutes, 660 g of water at 0°C was added, and the
The film was solidified by cooling to <RTIgt;°C.

This solution was stirred as it was for 30 minutes, 5rrLl of 37% formaldehyde aqueous solution was added, and after stirring for 20 minutes, 1N
-NaOH was gradually added dropwise to raise the pH to 10 in 30 minutes.

This was then heated to 50°C at a temperature increase rate of 1°C/min to complete the curing process.

In the thus obtained capsule liquid, triiron tetroxide powder 1702,
Carbon black IOP, styrene-butadiene copolymer dispersion (solid content 32%) 1569, and water-soluble silicone (5H28 manufactured by Toray Silicone) 0.5? Add
Stir in a homomixer for 1 hour to obtain a capsule slurry, which is then atomized using an atomizer at a temperature of 130°C and a temperature of 80 to 90°C at a pressure of 4.8 kg/cst and a dropping rate of 400 ml/hour. It was dried to obtain a dry developer for electrophotography.

Example 2 In Example 1, similar water-soluble silicone (KF-3 manufactured by Shin-Etsu Silicone Co., Ltd.) was used instead of water-soluble silicone 5H28.
51) A dry developer for electrophotography was obtained in the same manner using 0.3y.

Example 3 In Example 1, water-dispersible silicone (SH1036 manufactured by Toray Silicone Co., Ltd.) was used instead of water-soluble silicone 5H28.
) A dry developer for electrophotography was obtained in the same manner using 1.5P.

Comparative Example 1 A dry developer for electrophotography was obtained in the same manner as in Example 1 except that the water-soluble silicone was not used.

Example 4 Polyisobutylene 502 as a core material and an activator (manufactured by Nikko Chemical, Tl-1o) were added to 100 g of a 5% aqueous solution of acid-treated gelatin (isoelectric point 8.8) at 40°C adjusted to pH 10 with IN-NaOH. Add 1.5P, 10.00 Or
Disperse and emulsify for 10 minutes using a pm homomixer.

This solution was added at 40°C, adjusted to pH 10 with 1N-NaOH.
100 g of an aqueous solution of 5% gum arabic was added and stirred for 10 minutes, and then a 5% acetic acid aqueous solution was gradually added dropwise to lower the pH to 4.4 over an hour to cause phase separation to produce polyisobutylene. An encapsulated gelatin-gum arabic film was deposited.

After stirring this solution for an additional 10 minutes, 660 g of water at 0°C was added and cooled to 5°C to solidify the film.

This was stirred as it was for 30 minutes, 5 ml of 37% formaldehyde aqueous solution was added, and after stirring for 20 minutes, lN-N
AOH was gradually added dropwise, and the pH of the solution was adjusted for another 30 minutes.
increased to 10.

This liquid was then heated to 50° C. at a temperature increase rate of 1° C./min to complete the curing process.

Magnetic powder (Toda Kogyo, M
32) 1102, carbon black 10? , molar ratio 10
0:94:6 methyl methacrylate/n-butyl methacrylate/acrylic acid copolymer dispersion (solid content 33
%) 121 and water-soluble silicone (KF-341 manufactured by Shin-Etsu Silicone Co., Ltd.) 0.1 were added and stirred for 1 hour with a homomixer to form a capsule slurry, which was mixed using an atomizer at an inlet temperature of 130°C and an outlet temperature of 80°C. ~90'C1
Spray pressure 4.8kg/crA and dropping rate 400Tul
Spray drying was carried out under the conditions of /hour to obtain a dry developer for electrophotography.

Example 5 In Example 4, water-soluble silicone (manufactured by Toray Silicone Co., Ltd. 5) (37) was used instead of water-soluble silicone KF-351.
46) A dry developer for electrophotography was obtained in the same manner using 0.1.

Example 6 In Example 4, water-dispersible silicone (KM74 manufactured by Shin-Etsu Silicone Co., Ltd.) was used instead of water-soluble silicone KF-351.
) A dry developer for electrophotography was obtained in the same manner using 2.0P.

Comparative Example 2 A dry developer for electrophotography was obtained in the same manner as in Example 4 except that the water-soluble silicone KF-351 was used.

The properties of the developer obtained as follows are shown in the table below.

*Measurement method for fluidity An electromagnetic micro-type sieve shaker (Tsutsui Rikagaku Kikai KK) was used, and toner for NT-630 (KK) was used as the standard toner.
Accurately weigh out 102 (manufactured by Ricoh, containing silicone powder),
Place it gently on a 150-mesh sieve, and use a slideac voltmeter to adjust so that all the toner passes through in 100 seconds.

Next, the flowability of toner 10' is measured. was weighed, and the time taken for all the toner to pass was taken as the value of toner fluidity.

As can be seen from this table, the developers of Comparative Examples 1 and 2 in which no water-soluble or water-dispersible silicone was added had poor fluidity and a wide particle size distribution.

On the other hand, the developer to which water-soluble or water-dispersible silicone is added as in the present invention has improved fluidity and narrowed particle size distribution.

Claims (1)

[Claims] 1. A pressurized adhesive soft solid is provided as a core material, and a first wall mainly made of a film-forming polymeric material and a second wall mainly made of a synthetic resin are provided on the outside of the core material, and the core material, 1st
A dry developer for electrophotography, wherein at least one of the wall and the second wall contains a magnetic powder and a colorant, and the second wall further contains a water-soluble or water-dispersible silicone.