JPS5911102B2 - Pressure fixable magnetic microcapsule toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrostatic photographic toner, and more particularly to a magnetic microcapsule toner having pressure fixability.

Conventionally, the dry developing methods for electrostatic photography include the cascade method,
Both methods, such as the magnetic brush method, use a method in which carrier particles such as glass beads or iron powder are mixed as a developer, and the toner particles are charged by frictional electrification, which is brought into contact with the electrostatic latent image and visualized. 5 It has been done.

The toner particles used in these methods are made by finely pulverizing thermoplastic resin lumps in which colorants are uniformly dispersed, but in these methods, the toner particles are further pulverized during frictional charging with carrier particles. During operation, toner scattering not only contaminates the inside and outside of the copying apparatus 10, but also causes deterioration of carrier particles and deterioration of image quality, necessitating early replacement of the developer. Moreover, when thermally fixing an image obtained using such toner, it takes a long time to raise the temperature of the fixing device to the softening point of the toner15, and a large amount of power is consumed to maintain this temperature. It has the following disadvantages. On the other hand, in order to omit the step of mixing toner particles and carrier particles and eliminate the above-mentioned inconvenience, a simple development method is available in which a developer in which the toner particles themselves have magnetism is attached to a magnetic roller 20 for development. It has been developed, and part of it is shown in Japanese Patent Application Laid-open Nos. 49-4532 and 49-5035.

In addition, fixing methods are becoming simpler and lower in energy consumption, and the conventional heat fixing method is being replaced by a pressure fixing method that uses only pressure. Dry electrophotographic copying machines are also commercially available. As described above, the requirements for toner used in copying machines are that the magnetic field of the magnetic roller causes the roller surface 3 to
It has various properties such as magnetic properties and fluidity that allow it to easily adhere to zero, electrical properties that allow it to easily transfer to the electrostatic latent image on the image receiving surface, and pressure fixing properties that allow it to be fixed with as low a pressure as possible. This can be mentioned.

However, it is extremely difficult to obtain a toner that satisfies all of these properties at the same time.
In the case of the pressure-fixable magnetic toner described in No. 739, hydrophobic silica is mixed in to impart fluidity, but in such a toner, the hydrophobic silica impedes the fixing performance and reduces the amount of time required for fixing. The pressing force is extremely large, 300 to 400 pounds/inch, and there are still many drawbacks in practical use. The present invention improves the above-mentioned drawbacks, has sufficient magnetic properties, fluidity, and electrical properties, and can fix with low pressure.
Therefore, a practical pressure-fixable magnetic toner is provided.

The toner of the present invention is a microcapsule toner having a double capsule wall, and has the ability to form a hydrophilic film on the outside of a core material mainly consisting of a non-aqueous solution or dispersion of a soft solid that has adhesive properties under pressure at room temperature. A first wall mainly made of a polymer material and a second wall obtained from an aqueous suspension mainly made of a hard resin are sequentially provided, and a coloring agent and It contains magnetic particles separately or in a mixture.

The basic method for producing such a toner is to emulsify and disperse a non-aqueous solution or non-aqueous dispersion of a pressure-adhesive soft solid into an aqueous solution of a hydrophilic film-forming polymeric substance, and then add the dispersed particles to a core material. After encapsulation in water, this encapsulation liquid is mixed with an aqueous suspension of hard resin to form a capsule slurry, and this is spray-dried to perform double encapsulation. At this time, the colorant and magnetic particles are added separately or in a mixture to a non-aqueous solution (or non-aqueous dispersion) of a soft solid, an aqueous solution of a hydrophilic film-forming polymeric substance, and/or an aqueous suspension of a hard resin. Blend. Methods for encapsulating the core material include phase separation from an aqueous solution such as complex coacervation method, simple coacervation method, salt coacervation method, and polymer insolubilization method by PH change, temperature change, and solvent removal. Hydrophobic substances are treated by force in an aqueous medium, such as by polymerization, interfacial polymerization, and in-situ polymerization. - Any method that can be made into a package can be adopted.

Pressure-adhesive soft solids used as core materials include higher fatty acids such as stearic acid, palmitic acid, myristic acid, lauric acid, and puric acid, aluminum stearate, lead stearate, barium stearate tetraphosphate, and stearic acid. Higher fatty acid metal salts such as magnesium, zinc stearate, zinc palmitate, higher fatty acid derivatives such as hydrogenated castor oil, cocoa butter, methyl hydroxystearate, glycerol monohydroxystearate, octadecaneamide, hexadecaneamide, tetradecaneamide, dodecane Higher fatty acid amides such as amide, decane amide, octanamide, hexane amide, waxes such as beeswax, carnauba wax, microcrystalline wax, rosin, hydrogenated rosin, rosin derivatives such as rosin ester, dry oil type or semi-dry type Alkyd resins such as oil-type alkyds, rosin-modified alkyds, phenol-modified alkyds, and styrenated alkyds, epoxy-modified phenolic resins, natural resin-modified phenolic resins, amino resins, silicone resins, polyurethanes, area resins, condensation polymers such as polyesters, A copolymerized oligomer of acrylic acid and a long-chain alkyl acrylate, a copolymerized oligomer of acrylic acid and a long-chain alkyl methacrylate, a copolymerized oligomer of methacrylic acid and a long-chain alkyl acrylate, and a copolymerized oligomer of methacrylic acid and a long-chain alkyl methacrylate. copolymerized oligomer of styrene and long-chain alkyl acrylate, copolymerized oligomer of styrene and long-chain alkyl methacrylate, polyolefin such as polyethylene, ethylene-vinyl acetate copolymer, ethylene-vinyl alkyl ether Copolymers, maleic anhydride copolymers, asphalt, petroleum residues such as gilsonite, and rubbers such as isobutylene rubber, nitrile rubber, and chlorinated rubber are exemplified. Note that when a resin is used as the soft solid, one with a low molecular weight is suitable. Hydrophilic film-forming polymer substances include gum arabic, gelatin, albumin, sodium alginate, carboxymethyl cellulose, hydroxyethyl cellulose, ethylene-sodium maleic anhydride copolymer, polyvinyl methyl ether-maleic anhydride (or its ester) copolymer There are styrene-acrylic acid-butyl methacrylate copolymers, etc.

Hard resins include polycarbonate, polyester, polyamide, polyether, polyolefin, polystyrene, styrene - acrylate copolymer, styrene -
Methacrylate copolymer, styrene - ethylenically unsaturated monoolefin copolymer, styrene - vinyl ester copolymer, styrene - vinyl ether copolymer, styrene - acrylonitrile copolymer, styrene - methacrylonitrile copolymer, styrene - acrylamide copolymer,
Styrene - α-methylene fatty acid monocarboxylic acid ester copolymer, styrene - vinylidene halide copolymer,
Polyvinyl acetate or copolymers or blends of two or more of these are used.

Coloring agents include pigments such as carbon black and dyes such as oil black, and magnetic materials include metal powders such as iron, nickel, and cobalt, alloy powders of these metals, and fine particles such as magnetic iron oxide, carbonyl iron, and ferrite. or a mixture thereof (the particle size is preferably 1 μm or less).

Examples are shown below.

Example 1 0.57% of terephthaloyl chloride was dissolved in 62.5y of a 20wt% toluene solution of lauryl methacrylate polymer, and magnetic iron powder (M-32 manufactured by Toda Kogyo Co., Ltd.) 2 was added to this.
07 is dispersed to form a core material.

Next, this was emulsified and dispersed in 500 d of water in which 2.5 t of sodium bicarbonate and polyvinyl alcohol were dissolved, and 50 d of a 10 wt% hexamethylene diamine aqueous solution was added while stirring.
7 was added to form a polyamide capsule film around the emulsified droplets. On the other hand, water-dispersible carbon black (Colloidex Black 5, manufactured by Columbia Carbon Co., USA) 37 was dispersed in an aqueous suspension of polyvinyl acetate (A-522 manufactured by Daicel Corporation, solid content 50 wt%) 657, and this dispersion liquid was Mix uniformly with the capsule liquid prepared in step 1 to make capsule slurry.

Finally, this capsule slurry was spray-dried using a Niro atomizer at an inlet temperature of 135°C, an outlet temperature of 85°C, and a spraying pressure of 5.6 kg/Cd (compressor pressure), with magnetic particles in the core and carbon black on the outer wall. A double encapsulated pressure fixable magnetic microcapsule toner containing the following was obtained. Example 2 A 40wt% aliphatic hydrocarbon (Isopar H manufactured by Etsuo Standard) dispersion of vinyl acetate-lauryl methacrylate graft copolymer (dispersed in a swollen state) was heated to 62.5V with carbon black (Mitsubishi Chemical Corporation). ) Mitsubishi color carbon ◆44
)27 is dispersed, and 1 of terephthaloyl chloride is further dispersed.
A 0 wt% toluene solution 5f7 is dissolved to obtain a core material.

Next, this core material was emulsified and dispersed in 500 ml of water in which 2.5% of bicarbonate of soda and polyvinyl alcohol were dissolved, and a 10 wt % hexamethylene diamine aqueous solution 507 was added dropwise with stirring to form emulsified droplets of the core material. A dispersion of capsules coated with a polyamide film was prepared.

Further, the polyvinyl acetate aqueous suspension 657 of Example 1 and the magnetic iron powder 207 of Example 1 were uniformly mixed and dispersed to form a capsule slurry. Example 1 below
The capsule slurry was spray-dried according to the spraying method described above to obtain a pressure-fixable magnetic microcapsule toner which was double encapsulated and contained carbon black in the core and magnetic iron powder in the outer wall.
Example 3 10 of the lauryl methacrylate polymer in Example 1
Styrene-butadiene rubber (Solprene 303, manufactured by AA Chemical Co., USA) was used instead of the wt% toluene solution, and an aqueous suspension of polystyrene (DOw-201, manufactured by Tau Chemical Co., USA, solid content 50 wt%) was used instead of the aqueous suspension of polyvinyl acetate. Example 1 using
The above method was repeated to obtain a similar pressure-fixable magnetic microcapsule toner.

Example 4 In Example 2, instead of the vinyl acetate-lauryl methacrylate graft copolymer dispersion, styrene-isobutyl methacrylate copolymer (molar ratio 1/9) was used.
Using 0wt% toluene solution, 10wt% hexamethylenediamine 507 was mixed with 10wt% ethylenediamine 25t.
A similar pressure-fixable magnetic microcapsule toner was obtained instead.

Example 5 62.5 f of a 50 Wt% toluene solution of isobutyl methacrylate-lauryl methacrylate copolymer (molar ratio 2/8)! and terephthaloyl chloride 0.5
2 parts each of sodium bicarbonate and polyvinyl alcohol.

Emulsify and disperse 5y in 500ml of water, and add 50wt% hexamethylene diamine aqueous solution to this while stirring.
y was added dropwise to prepare a dispersion of capsules in which the emulsion droplets were covered with a polyamide film.

Next, the aqueous polystyrene suspension 607 used in Example 3, carbon black 27, and ultrafine iron-nickel alloy powder (Vacuum Mettallu) were added to this solution.
(manufactured by Rgjcal) 20y, uniformly dispersed to form a capsule slurry, and finally spray-dried using a nitro atomizer under conditions of an inlet temperature of 135°C, an outlet temperature of 85°C, and a compressor pressure of 6.0kg/Cd. A double encapsulated pressure fixable magnetic microcapsule toner having magnetic particles and carbon black was obtained. Example 6 3.5wt% gum arabic aqueous solution 100V 1NN&0
50 tons of the 10 wt% toluene solution of the styrene-butadiene rubber of Example 3 in which 0.5 tons of oil-soluble dye (Oil Black EB manufactured by Orient Chemical Co., Ltd.) was dissolved was emulsified and dispersed. Mix 100f of a 5wt% gelatin aqueous solution of PHLO into the solution and raise the temperature to 50%.
While maintaining the temperature at ±1° C. and gently stirring, acetic acid was added dropwise over about 2 hours until the pH reached 4.8, causing phase separation of gelatin and gum arabic mixed particles around the emulsion droplets.

Next, 150 r of water at 5°C was added to this system, and the mixture was stirred for 30 minutes while maintaining this temperature.
ZAN-119) 10wt% aqueous solution 301 and 37w
After adding 3y of t% formaldehyde aqueous solution, the pH was adjusted to 1.
Adjusted to 0. The temperature was gradually raised to 50° C. over about 1 hour with continued stirring to harden the obtained capsule walls, and then 2 tons of the aqueous polystyrene suspension 50V1 carbon black of Example 3 and Example 5 were added to the capsule dispersion. A capsule slurry was prepared by mixing and dispersing 20 tons of iron to nickel alloy fine powder. This capsule slurry was spray-dried under the spray-drying conditions of Example 5 to obtain a double-encapsulated pressure-fixable magnetic microcapsule toner. Example 7 A mixture of 37wt% formaldehyde aqueous solution and urea 100r was purified with 10wt% ethanolamine aqueous solution.
The temperature was adjusted to 7.5 and stirred at 70° C. for about 2 hours to prepare an initial mixture of urea and formaldehyde.

Next, in 200 d of an aqueous solution diluted to 5 wt%, 80 liters of a toluene solution of styrene-butadiene rubber colored with an oil-soluble dye and 3 t of the water-dispersible carbon black of Example 1 were mixed uniformly in the same way as in Example 6. After dispersion, citric acid was added to the dispersion while stirring to adjust the pH to 3.
5 and continued stirring for about 5 hours while keeping the temperature at 48±2°C, and encapsulated by precipitation hardening of the urea-formaldehyde resin containing carbon black around the emulsified droplets of the styrene-butadiene rubber solution. Summer. Next, this capsule dispersion was added with 110y of the same polystyrene aqueous suspension as in Example 3 and 35y of magnetic iron powder.
was uniformly dispersed to form a capsule slurry, which was spray-dried under the same spray-drying conditions as in Example 5 to obtain a pressure-fixable magnetic microcapsule toner in which double capsules were formed. Example 8 In Example 6, instead of the toluene solution of styrene-butadiene rubber, 10r of aluminum stearate was heated and dissolved in 40f of toluene. A pressure-fixable magnetic microcapsule toner was obtained by following the method of Example 6, except that 0.5 t of Oil Black HBB (manufactured by Co., Ltd.) was dissolved and this was used as the core material.

Comparative Example For comparison, a toner was prepared according to the method described in the Examples of JP-A-49-17739.

That is, two volumes each of polystyrene (PS-2 manufactured by Tau Chemical Co., USA) and phenol-formaldehyde resin (ERLB-0449 manufactured by Union Carbide Co., USA) were added to a mixed solvent of 4507 chloroform and cyclohexane at a volume ratio of 4/3.
Carbon black (Peerless 155 manufactured by Colombia Carbon Co., USA) 2.57 and nickel~iron~'::12 gold alloy (AcumMetal
After uniformly dispersing 57 (manufactured by Lurgiml), the inlet temperature was 76°C, the outlet temperature was 53°C, and the compressor pressure was 5k9/Cri. It was spray-dried under the following conditions to obtain a pressure fixable magnetic toner for comparison.

Using the toners obtained in the above Examples and Comparative Examples, an electrostatic latent image formed on a commercially available electrophotographic photosensitive material was developed using a commercially available developing device, and after being transferred to transfer paper, variable pressure pressure was applied. The image was fixed by passing it through a pair of fixing rollers under pressure to form an image.

Claims (1)

[Claims] 1 A first wall mainly made of a hydrophilic film-forming polymeric material and a second wall obtained from an aqueous suspension mainly made of a hard resin on the outside of a core material mainly made of a non-aqueous solution or dispersion of a soft solid. A pressure fixable magnetic microcapsule toner, characterized in that the core material and/or the outer wall further contain a colorant and magnetic particles, either separately or in a mixture.