JPS62242959A - Capsuled toner - Google Patents

Abstract

PURPOSE:To provide positive triboelectric chargeability to a capsuled toner by forming the shell with polyurethane contg. isocyanate units having the structure of isocyanurate and/or polyurea. CONSTITUTION:The shell of a capsuled toner is formed with polyurethane and/or polyurea. The polyurethane is obtd. by reacting isocyanate having the structure of isocyanurate with polyol or polyamine by interfacial polymn. or other method. The isocyanate used is preferably derived from a trimer of hexamethylene diisocyanate and/or a trimer of tolylene diisocyanate. The preferred amount of the shell is 5-30wt% of the amount of the capsuled toner. The resulting capsuled toner shows high positive triboelectric chargeability, the shell is made dense and a clear image is obtd.

Description

Detailed Description of the Invention [Field of the Invention] The present invention relates to a capsule toner used for converting a latent image formed in an electrophotographic recording method into a visible image. This invention relates to a capsule toner with excellent charging properties.

[Background of the Invention 1] There are three known methods for fixing toner images in recording methods such as electrophotography: heat fixing, solvent fixing, and pressure fixing. and.

Due to environmental concerns, heat fixing methods and pressure fixing methods that do not use solvents are often used these days.

Toners formed by binding display recording materials with binders have been used in the heat fixing method. The same type of toner is also used in the pressurized chamber 77 method, but recently the use of capsule toner has been considered.

Capsule toner is a toner in the form of microcapsules obtained by forming a resin shell that can be destroyed by applying pressure around a core material containing a display recording material such as carbon black and a binder.

[Prior art and problems] Toner used as a developer for electrophotography must have good powder properties, excellent developability, and do not stain the surface of the photoreceptor, which is the surface on which a latent image is formed. It is said that In addition, the toner used in the pressure fixing method has good pressure fixing properties and is unlikely to cause offset phenomenon (a phenomenon in which toner adheres to the pressure roller surface and stains it) on the pressure roller used for pressure fixing. It becomes necessary.

Therefore, the toner used in the pressure fixing method is required to have excellent properties in various aspects such as toner fluidity, storage stability, non-offset property, and chargeability depending on the developing method used. The inferiority of any of these results in poor quality of the resulting visible image.

Furthermore, toners with insulating surfaces have generally been used as developers for electrophotography, but recently, toners with appropriate positive or negative triboelectric properties have been used on the toner surfaces. being developed.

In other words, the toner used in electrophotography is a method in which the toner is (1) electrically charged by rubbing it against carrier particles such as iron powder or Celsius skin, and this charged toner is attracted to a latent image. It is necessary to have negative or positive triboelectric chargeability corresponding to the chargeability of the latent image, which is defined as positive or negative depending on the type.

Up to now, capsule toners with an outer shell made of polyurethane resin or polyurea resin formed from isocyanate, polyol, polyamine, etc. have been proposed as capsule toners with excellent triboelectric charging properties (Japanese Patent Laid-Open No. 57-179860). Public bulletin).

According to this, since the polyurethane resin or polyurea resin is a resin that has negative triboelectricity, the surface of the capsule toner whose outer shell is made of the resin is negatively abraded! M4rP
Power up.

Furthermore, since the polyurethane resin or polyurea resin has appropriate strength and flexibility as the outer shell material, the outer shell of the capsule toner made of the resin is extremely dense, and the powder properties are also improved.

Therefore, if it is necessary to have a negative triboelectric chargeability corresponding to the chargeability of a latent image that is positively determined depending on the type of device, the capsule toner having an outer shell made of polyurethane resin or polyurea resin may be used as a developer. It is particularly effective as a

However, in contrast to the above-mentioned case, when it is necessary to have positive triboelectric charging properties, the capsule toner having an outer shell made of the polyurethane resin or polyurea resin is not suitable for use as a developer.

[Object of the Invention] An object of the present invention is to provide a novel electrophotographic capsule toner having excellent positive triboelectric charging properties.

[Summary of the Invention] The present invention provides a capsule toner comprising a core material containing a binder containing a polymer and an oil-based solvent and a display/recording material, and an outer shell formed around the core material. The capsule toner is characterized in that the outer shell is made of a polyurethane resin and/or a polyurea resin containing an isocyanate unit having an isocyanurate structure as an isocyanate unit.

[Effects of the Invention] The capsule toner of the present invention has a high positive J1? since the outer shell is made of a polyurethane resin and/or a polyurea resin containing isocyanate units having an isocyanurate structure as repeating isocyanate units. ! It exhibits triboelectric properties and has a dense outer shell, resulting in clear images. Therefore, the capsule toner of the present invention is excellent as a developer that is required to have positive triboelectric charging properties for use in electrophotography.

[Detailed Description of the Invention] The capsule toner of the present invention has a basic structure consisting of a core material and an outer shell formed around the core material.

The core substance of the capsule toner of the present invention exhibits a high viscosity oily state,
Included are binders consisting of polymers and oily solvents, and display and recording materials.

Among the components constituting the core material of the capsule toner of the present invention, there are no particular limitations on the polymer used as the binder component. Examples of polymers include polyolefins, olefin copolymers, styrene resins, styrene-butadiene copolymers, epoxy resins, polyesters, rubbers, polyvinylpyrrolidone, polyamides, coumaron-indene copolymers, methyl vinyl ether-maleic anhydride copolymers. , amino resins, polyurethanes, polyureas, homopolymers or copolymers of acrylic esters, homopolymers or copolymers of methacrylic esters,
Examples include copolymer oligomers of acrylic acid and long-chain alkyl methacrylate, polyvinyl acetate, and polyvinyl chloride, and these can be used singly or in combination.

Particularly preferred polymers for the binder are homopolymers or copolymers of acrylic acid esters,
A homopolymer or copolymer of methacrylic acid ester, or a styrene-butadiene copolymer.

There are no particular restrictions on the oily solvent used as a component of the binder, but it is preferable to use a high-boiling point solvent (hereinafter also simply referred to as a high-boiling point solvent) that can dissolve or swell the above-mentioned polymer and has a boiling point of 150° C. or higher.

Examples of high-boiling solvents include phthalates (e.g., diethyl phthalate, dibutyl phthalate); aliphatic dicarboxylic esters (e.g., diethyl malonate, dimethyl oxalate); diphosphates (e.g., tricresyl phosphate). , tricresyl phosphate); Citric acid esters (e.g., 0-acetyl triethyl citrate, tributyl citrate); Benzoic acid esters (e.g., butyl benzoate, hexyl benzoate); Fatty acid esters (e.g., hexadecyl myristate); , dioctyl adipate): Alkylnaphthalenes (e.g., methylnaphthalene, dimethylnaphthalene, monoisopropylnaphthalene, diisopropylnaphthalene); Alkyldiphenyl ethers (e.g., 0-1m-1p-methyldiphenyl ether): Amides of higher fatty acids or aromatic sulfonic acids Compounds (e.g., N,N-dimethyllauramide, N-butylbenzenesulfonamide), nitrimellitic acid esters (e.g., trioctyl trimellitate) and diarylalkanes (e.g., diarylmethane such as dimethylphenylphenylmethane, Examples include diarylethanes such as 1-phenyl-1-methylphenylethane, 1-dimethylphenyl-1-phenylethane, and 1-ethylphenyl-1-phenylethane.

Preferably, the binder is a composition comprising a polymer and a high boiling point solvent.

The mixing ratio of the polymer and the high boiling point solvent is desirably in the range of 1 to 100 in terms of polymer/high boiling point solvent ratio, and the binder has a viscosity of 1000 to 100.
0000 cp (25°C) (preferably 500 cp)
A high viscosity oily liquid (0 to 40,000 cp) is desirable.

In addition, the binder can be prepared by further using an organic liquid (hereinafter also simply referred to as a non-dissolving organic liquid) having a boiling point within the range of 100 to 250°C that does not substantially dissolve or swell the polymer. It is also preferable that the composition is a composition containing three components: , a high boiling point solvent, and an insoluble organic liquid.

Examples of insoluble organic liquids include paraffinic hydrocarbons, naphthenic hydrocarbons, and organic liquid mixtures containing these as main components. Examples suitable for use as the insoluble organic liquid to be contained in the core material of the present invention include boiling point ranges (initial boiling point to
Paraffinic hydrocarbons at 177°C (e.g. l5opar
G, trade name, manufactured by Kokuson Kagaku ■, hereinafter the same), paraffinic hydrocarbons with a boiling point range of 174 to 189°C (e.g., l
5opar11), paraffinic hydrocarbons with a boiling point range of 188-210'C (e.g. rsopar L), paraffinic hydrocarbons with a boiling point range of 207-258°C (e.g. lsoparM), boiling points range of 162-197°C Naphthenic hydrocarbons (e.g., 5IIELLSOL-040
, trade name, manufactured by Shell Chemical Co., Ltd. (hereinafter the same), boiling point range 1
Naphthenic hydrocarbons at 85-220°C (e.g. 5HELL
SQL-D60) and the boiling point range is 195-251"C
naphthenic hydrocarbons (e.g., 5HELLSQL-D7
0).

The insoluble organic liquid can be mixed with the above-mentioned high boiling point solvent at any ratio of 2:1, but generally the weight ratio of high boiling point solvent/insoluble organic liquid is 9/l to 1/l. It is preferable to mix within the range of 9.

Further, the mixing ratio of the [polymer 10 high boiling point solvent] and the insoluble organic liquid is preferably in the range of O.l to Zoo in terms of weight ratio of [polymer 10 high boiling point solvent]/insoluble organic liquid.

Display and recording materials for electrophotographic toners include commonly used black toners such as carbon black and grafted carbon black, and various chromatic colorants such as eight colors, red and yellow. is also used. The capsule toner of the present invention can also use these known display and recording materials as display and recording materials.

The core material of the capsule toner of the present invention may contain magnetic particles. As the magnetic particles, known magnetic particles (magnetizable particulate matter) for magnetic toner can be used. Examples of such magnetic particles include magnetic particles made of a simple metal such as cobalt, iron, or nickel, an alloy, or a metal compound.

In addition, when colored magnetic particles such as black magnetite are used as the magnetic particles, the colored magnetic particles such as magnetite can also be used as a component that functions as both the magnetic particles and the blue material [1].

The outer shell of the capsule toner of the present invention is characterized in that it is made of a polyurethane resin and/or a polyurea resin containing isocyanate units having an isocyanurate structure as repeating isocyanate units.

The outer shell of the capsule toner of the present invention has positive triboelectric charging properties and is highly dense, and is therefore easily attracted to a negatively charged latent image.

The weight of the outer shell of the capsule toner of the present invention is preferably in the range of 5 to 30% by weight based on the total weight of the capsule toner.

Next, a capsule toner comprising an outer shell of a polyurethane resin and/or a polyurea resin containing an isocyanate unit having an incyanurate structure as the unagigae isocyanate unit of the present invention will be described below.

In an aqueous medium, display and recording materials and binders (
A method of manufacturing a capsule toner by forming an outer shell made of polyurethane resin and/or polyurea resin around a core material dispersed in the form of oil droplets containing magnetic particles (if desired) is already known. These known methods can also be used to produce the capsule toner of the present invention.

For example, methods for producing microcapsules using polymerization reactions that can be used to produce capsule toner include interfacial polymerization, internal polymerization, and external polymerization.

The outer shell made of the polyurethane resin and/or polyurea resin of the present invention can be easily formed into the outer shell of the microcapsule by reacting an isocyanate having an isocyanurate structure with a polyol and/or polyamine in an aqueous medium by an interfacial polymerization method. It can be formed as

During the reaction for forming the outer shell, it is preferable to carry out the reaction for forming the outer shell while removing the organic solvent contained in the reaction system.

Examples of the isocyanate having an isocyanurate structure used to produce the polyurethane resin and/or polyurea resin described in item 1-1 include trimers of hexamethylene diisocyanate, trimers of tolylene diisocyanate, and mixtures thereof. I can name some things.

Examples of trimers of hexamethylene diisocyanate include Coronate EH (manufactured by Nippon Polyurethane) and Desmodur N3390 (Sumitomo Bayer Urethane 15).
i1) ;) - King of lylene diisocyanate? As an example of the body, Sumidur FL (made by Resident Bayer Urethane ■)
; Examples of these mixtures include Desmodur HL (
Sumitomo Bayer Urethane 5A), Coronate 2031 (
(manufactured by Nippon Polyurethane), Suprasec 3240 and 3340 (manufactured by Nippon Polyurethane), Takenate D20
0 and D202 (manufactured by Narita Pharmaceutical Co., Ltd.), Desmodur IL (manufactured by Sumitomo Bayer Urethane), and Burnock D800 (manufactured by Dainippon Ink & Chemicals, Ltd.), which are generally commercially available.

Specific examples of polyamine compounds include ethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, p-phenylenecyamine, m-phenylenecyamine, 2-hydroxytrimethylenediamine, diethylenetriamine, triethylenetetraamine. , diethylaminopropylamine, tetraethylenepentamine, and adducts of epoxy compounds and amines.

Examples of specific polyol compounds include ethylene glycol, 1,4-butanediol, hexamethylene glycol, hydroquinone, resorcinol, glycerin, pentaerythritol, bisphenol A, alkali salts of 4-chlorresorcinol, 2,2° - Alkaline salt of bis(4-hydroxyphenyl)propane, alkaline salt of l,5-dihydroxynaphthalene, alkaline salt of phenolphthalene, alkaline salt of phenol formaldehyde initial condensate, alkaline salt of 4.4°-dihydroxydiphenylsulfone. , 2,4-dihydroxybenzophenone alkali salt, 4,4'-dihydroxybenzophenone alkali salt, 2,4-dihydroxybenzaldehyde alkali salt, melamine/formaldehyde initial condensate, urea/formaldehyde initial condensate. .

The microcapsules with the outer shell formed are then washed with water.

The microcapsules are then separated from the liquid phase and dried. This separation and drying operation is usually carried out by spray drying a dispersion containing microcapsules or heating and drying a slurry containing microcapsules.

Note that it is desirable that the separated and dried microcapsules be further subjected to heat treatment. This heat treatment particularly improves the powder properties of the capsule toner.

The heat treatment is preferably carried out at a temperature in the range of 50 to 300°C, and particularly preferably in the range of 80 to 150°C. The heating time can be appropriately determined depending on the heating temperature, the type of core material used, etc., but is preferably heated for 2 to 24 hours.

If desired, a charge control agent such as nigrosine or other arbitrary additives can be added to the outer shell of the capsule toner of the present invention. These additive substances can be incorporated into the outer shell of the capsule toner at any time, such as when the outer shell is formed or after the capsule toner is separated and dried.

Next, Examples and Comparative Examples of the present invention will be shown. In the Examples and Comparative Examples, "1%" means "weight%" unless otherwise specified.

[Example 1] Polyisobutyl methacrylate (trade name Niacrybase, MM-2002-2: manufactured by Fujisuke Kasei ■) 20 Tama i@g
40 g of a solution of l-isopropyl-phenyl-2-phenylethane containing 10 wt.
g in an automatic mortar to create a dispersion (magnetic ink).
: Manufactured by A.

Separately, add 20 g of paraffin oil with a boiling point of 170°C to 190°C to 60 g of ethyl acetate, and add dimethylphenylsiloxane (
Product name: Silicone KF50゜3000cs: Shin-Etsu Chemical ■) 3g, hexamethylene diisocyanate trimer (Product name: Coronate EH: Japan Polyurethane ■)
A solution was prepared by dissolving 20 g of the above-mentioned dispersion liquid (1M ink) to prepare an oily phase.

However, this oily phase mixed liquid (mixture of core material and outer shell forming material) was prepared while controlling the liquid temperature to 25°C or less.

An aqueous medium was prepared by adding 0.2 g of diethylenetriamine to 200 g of a 4% by weight aqueous solution of methylcellulose (methoxy group substitution degree = 1.8, average molecular weight: 15000),
The temperature of this aqueous medium was cooled to 15°C.

The oily phase mixed liquid was emulsified and dispersed in this aqueous medium to obtain an oil-in-water emulsion in which the average size of oil droplets in the emulsion was about 121 Lm.

Approximately 10 minutes after preparing the emulsion, 50 g of a 2.5% by weight aqueous solution of diethylenetriamine was gradually added dropwise, and the emulsion was stirred for 3 hours while removing the solvent to complete encapsulation. Next, this microcapsule dispersion was centrifuged at 5000 rpm to separate the generated microcapsules from the methylcellulose-containing aqueous solution (clear liquid), and the resulting microcapsule slurry was dispersed in water to form a 30% dispersion. Prepared. The resulting dispersion was centrifuged again, and the resulting microcapsule slurry was dispersed in water to again prepare a 30% dispersion. Centrifugation as described in
A water washing operation consisting of dispersion was performed once more, and 2% by weight of hydrophobic silica (RA-2008, manufactured by Nippon Aerosil ■) was added to the microcapsule slurry obtained by centrifugation, mixed, and heated in an oven for 60 minutes. A capsule toner consisting of an outer shell of polyurea resin was prepared by drying at ℃.

The obtained capsule toner was transferred to a carrier (DSP-132
, manufactured by Dowa Iron Powder Works

In addition, a negatively charged electrostatic latent image formed by a normal electrophotographic method using the obtained capsule toner was developed by a magnetic brush method, and then transferred onto plain paper at a rate of 150 kg/cm.
It was established under the pressure of '. The fixed visible image was clear and fog-free.

[Comparative Example] In Example 1, instead of the isocyanate having an isocyanurate structure, an addition compound of 3 moles of hexamethylene diisocyanate and 1 mole of trimethylolpropane (trade name:
Burnock D-950: Large [manufactured by 1 ink chemical industry ■]
The procedure was repeated in the same manner as in Example 1, except that 1Og and an addition compound of 3 moles of tolylene diisocyanate and 1 mole of trimethylolpropane (trade name: Burnock D-750: manufactured by Dainippon Ink & Chemicals) were used. The capsule toner consists of an outer shell made of polyurea resin.

The amount of charge of the obtained capsule toner was determined in the same manner as in Example 1 and was found to be 5 u-gq/g.

In addition, a negatively charged electrostatic latent image was formed using the obtained capsule toner by the same electrophotographic method as in Example 1, and then developed by a magnetic brush method, and then transferred to plain paper at 150K.
When the image was fixed at a pressure of g/cm2, the density of one image was too low to be suitable for practical use.

Claims (1)

[Claims] 1. A capsule toner comprising a core material containing a binder containing a polymer and an oil-based solvent and a display/recording material, and an outer shell formed around the core material, the capsule toner comprising a core material containing a binder containing a polymer and an oil-based solvent, and an outer shell formed around the core material, wherein A capsule toner characterized in that the outer shell is made of a polyurethane resin and/or a polyurea resin containing an isocyanate unit having an isocyanurate structure as a unit. 2. The isocyanate unit having an isocyanurate structure is derived from at least one isocyanate having an isocyanurate structure selected from the group consisting of a trimer of hexamethylene diisocyanate and a trimer of tolylene diisocyanate. The capsule toner according to claim 1. 3. The weight of the outer shell is 5% relative to the total weight of the capsule toner.
The capsule toner according to claim 1, wherein the content is in the range of 30% by weight.