JPS60198558A - Production of capsule toner - Google Patents

Abstract

PURPOSE:To improve a powder characteristic and to enable formation of a sharp image even if environmental conditions fluctuate by performing formation of the shell of a microcapsule in an aq. medium contg. pulverous solid particles under dispersion. CONSTITUTION:A shell is formed around an oil drop-like core material contg. pulverous solid particles, display recording material and binder dispersed in an aq. medium to form a microcapsule. Such microcapsule is separated from the aq. medium and is washed and dried to obtain a capsule toner. There are CaCO3, MgCO3, BaCO3, BaSO4, SiO2, TiO2, Al2O3, fine granular carbon and fine granular polymer material as the pulverous solid particles and the average grain size thereof is preferably <=1mum. There are a polurea resin, polyurethane resin, etc. as the shell thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a toner used for converting a latent image formed in an electrostatic recording method into a visible image. More specifically, the present invention relates to a method for producing a capsule toner having particularly improved powder characteristics.

[Description of technical field] The electrostatic recording method, which is generally called electrophotography, is an iμ
The toner image formed on the image is transferred to a support medium J such as transfer paper.
This is a recording method in which the image is transferred to the support medium 1- and visualized by fixing it on the supporting medium 1-. There are three known methods for fixing a toner image on a support medium: heat fixing, solvent fixing, and pressure fixing.

Since the pressure foot 11 method does not use heat or solvent, there are no problems associated with methods such as heating chamber A' or solvent fixing, and the access time is fast, making it capable of keeping up with high-speed fixing methods. It inherently has various advantages such as:

However, the pressure fixing method has poor fixing properties compared to fixing methods such as heat fixing, and the fixed image is easily peeled off when rubbed. Since X pressure is required, fatigue of the medium is likely to occur due to destruction of the m-fibers of the support medium such as transfer paper.

In addition, there are various problems such as the surface of the support medium tends to become excessively glossy, and there are limits to the miniaturization of the pressure roller that applies high pressure, which limits the miniaturization of the entire copying device. There is.

In order to solve the above problem 4 associated with the pressure fixing method, a capsule toner in which I-ner is contained in microcapsules has already been developed. Capsule toner - A pressure of l4 is applied around the core material containing the display recording material.
This is a toner in the form of microcapsules that is obtained by forming an outer shell that has the property of being destroyed. Capsule toner is said to be a toner suitable for the pressure fixing method because it does not require high pressure for fixing and has excellent fixing properties.

[Problems with the Prior Art] However, conventionally known capsule toners cannot necessarily be said to be satisfactory in terms of various properties originally required as toners for electrophotography.

In other words, toner used as an electrophotographic developer is required to have good powder characteristics, excellent developing performance, and not to stain the surface of the photoreceptor, which is the surface on which a latent image is formed. In the case of a component development method, it is necessary that the surface of the carrier particles used is not contaminated. In addition, the toner used in the pressure fixing method must have good pressure fixing properties and be unlikely to cause an offset phenomenon (a phenomenon in which the toner sticks to the pressure roller surface and stains it) on the pressure roller used for pressure fixing. etc. are necessary.

Therefore, the toner used in the pressure chamber 7 method is determined depending on its powder properties, fixability to support media such as paper (including the shelf life of the fixed image), non-offset properties, and chargeability depending on the developing method used. All properties such as electrical properties and/or electrical conductivity must be at a high level. However, the capsule toners known so far have not always been satisfactory in terms of the above-mentioned properties.

For example, a common manufacturing method for capsule toner is to form microcapsules by forming an outer shell made of a resin material around a hydrophobic core material containing a display recording material dispersed as microdroplets in an aqueous medium. A method is known in which JLML and then this microcapsule dispersion are made into a powdered capsule toner using a drying method such as spray drying.

However, the capsule toner obtained by the above manufacturing method does not have sufficient powder properties, and after dry cooking, such a capsule toner may form a lump due to secondary aggregation of a large number of capsule particles. Even if it is in a powder state immediately after drying, it tends to aggregate if it is placed in a high humidity or high temperature environment or left in the air at room temperature for a long period of time. Furthermore, aggregation of capsule toner often occurs during the developing process in an actual developing device, and in such a case, problems such as a significant decrease in resolution of the developed visible image occur.

[Object of Unreleased 'II] An object of the present invention is to provide a method for producing a capsule toner with good powder properties and less secondary aggregation in a developing device or during storage. More specifically, the present invention includes:
The object of the present invention is to provide a method for producing a capsule toner that makes it possible to always form clear images even under fluctuations in normal environmental conditions by improving the powder properties of the capsule toner.

[Summary of the Invention] The present invention involves forming microcapsules by forming an outer shell around an oil droplet-like core material containing a display recording material and a binder dispersed in an aqueous medium, and then separating the microcapsules from the aqueous medium. Provided is a method for producing a capsule toner, characterized in that the formation of the outer shell is carried out in the aqueous medium containing fine solid particles dispersed therein. It is something to do.

E Effects of the present invention] The capsule toner obtained by the production method of the present invention has excellent powder properties such as cohesiveness, especially since the solid particles are attached to or contained on the surface of the outer shell. Therefore, it exhibits excellent properties as a developer used for carrying out electrophotography.

[Detailed Description of the Invention] In a liquid medium such as ice, an oil droplet core material containing a display recording material dispersed in the medium and a binder which is an auxiliary material for fusing the display recording material to a support medium is prepared. As mentioned above, methods for preparing microcapsules by forming an outer shell around them are already known.

Generally, a binder, an oily solvent, a display/recording material, etc. are used as the core material of a capsule toner.

When carrying out the method for producing a capsule toner of the present invention, examples of polymers that can be used as binder components among the components constituting the core material include the following compounds.

Polyolefin, olefin copolymer, styrene resin, styrene-butadiene copolymer, epoxy resin,
Polyester, rubber, polyvinylpyrrolidone, polyamide, coumaron/indene copolymer, methyl vinyl ether/maleic anhydride copolymer, amino resin, polyurethane, polyurea, homopolymer or copolymer of acrylic ester, homopolymer or methacrylic ester Copolymer, copolymer oligomer of acrylic acid and long-chain alkyl methacrylate, polyacid-resistant vinyl, polyvinyl chloride.

Particularly preferred as the binder polymer are homopolymers or copolymers of acrylic esters, homopolymers or copolymers of methacrylic esters, or styrene-butadiene copolymers.

Examples of oil-based solvents that can be used as a component of the binder include high-boiling point solvents (hereinafter also simply referred to as high-boiling point solvents) with a boiling point of 150 ° C or more that can dissolve or swell the polymer described in -1-. can. Examples of this high boiling point solvent are described below.

Phthalate esters (e.g., diethyl phthalate, dibutyl phthalate); aliphatic dicarboxylic acid esters (e.g.,
diethyl malonate, dimethyl oxalate) diphosphate esters (e.g., tricresyl phosphate, tricresyl phosphate); citric acid esters (e.g., 0-acetyl triethyl silicate, tributyl citrate); benzoate esters (e.g., butylbenzony-1, hexylbenzoate); aliphatic acid esters (e.g., hexadecyl myristate, dioctyl adipate); alkylnaphthalenes (e.g., methylnaphthalene, dimethylnaphthalene, monoisopropylnaphthalene, diisopropylnaphthalene) ; Alkyldiphenyl ethers (e.g., 0-
1m-1p-methyl diphenyl ether); higher fatty acids or aromatic sulfone amide compounds (e.g., N, N
-dimethyllauramide, N-butylbenzenesulfonamide); trimellitic acid esters (e.g., trioctyl trimellitate-1); diarylalkanes (e.g., diarylmethane such as dimethylphenylphenylmethane, l-phenyl-1); -diarylethanes such as methylphenylethane, l-dimethylphenyl-1-phenylethane, l-ethylphenyl-1-phenylethane).

Oil-based solvents that can be used as a component of the binder include, in addition to high-boiling point solvents, temperatures at 100 to 120°C (100 to 120°C) that do not substantially dissolve or swell the polymer contained in the core material. Preferably 140-220
Inorganic liquids (hereinafter also simply referred to as organic liquids) having a lighting temperature in the range of 100° C.) can also be mentioned. As the organic liquid, an aliphatic saturated hydrocarbon or the like can be used.

Preferably, the binder is a composition containing a polymer k Krj molten melt and optionally an organic liquid.

Black toners such as carbon black and grafted carbon black are generally used as display and recording materials for electrophotographic toners, but various chromatic colorants such as 17 colors, red, and yellow are also used. It is used. 1! by the manufacturing method of the present invention! These known display and recording materials can also be used as the display and recording materials used in the capsule toner.

The core material of the capsule toner obtained by the manufacturing method 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 metals such as cobalt, iron, or nickel, single substances, alloys, or metal compounds. 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 serves as both the magnetic particles and the display recording material.

The resin forming the outer shell of the capsule toner obtained by the method of the present invention is not particularly limited as long as it can form an outer shell around the oil droplet-like core substance in an aqueous medium.
Considering the characteristics as a capsule toner, the outer shell resin is preferably polyurea, polyurethane, polyamide, or polyester. These resins can be used alone or as a mixture for forming the outer shell. Then, according to the method of the present invention 1! It is particularly preferable that the capsule toner shown in FIG.

The method for producing the undeveloped Zino capsule toner can utilize a known method for producing a capsule toner, which consists of forming a resin shell around a core material through a polymerization reaction.

Next, the production capacity V of the capsule toner of the present invention will be explained by taking as an example a method V for producing a capsule toner made of an outer shell of polyurethane resin or polyurea resin.

In an aqueous medium, display and recording materials and binders (
There is already a known method for manufacturing microcapsules by forming an outer shell made of polyurea resin and/or polyurethane resin around a core material that is separated into oil droplets and containing magnetic particles (if desired). These known methods can also be used in the present invention.

Examples of the method for forming the outer shell that can be used as the method for producing the capsule toner of the present invention include the following.

An interfacial polymerization method can be mentioned. Further, other methods for forming the outer shell that can be used as a method for manufacturing the capsule toner of the present invention include an internal polymerization method and an external polymerization method.

The outer shell made of polyurea resin and/or polyurethane resin is made of polyisocyanate such as diisocyanate, triisocyanate, tetraisocyanate, polyisocyanate prepolymer, diamine, triamine,
Easily formed as the outer shell of microcapsules by reacting polyamines such as tetraamine, prepolymers containing two or more amino groups, hyherazine and its derivatives, polyols, etc. in a wood melt using an interfacial polymerization method. is known to be possible.

Further, a composite wall made of polyurea resin and/or polyurethane and polyamide resin which is preferable as the outer shell of the capsule toner of the present invention, for example, a composite wall made of polyurea resin and polyamide resin, a composite wall made of polyurethane resin and polyamide resin, or, A composite wall made of polyurea resin, polyurethane resin and polyamide resin can be manufactured by the following method.

Composite walls made of polyurea resin and polyamide resin, composite walls made of polyurethane resin and polyamide resin, for example, use polyisocyanate, acid chloride, polyamine and polyol, and adjust the pH of the emulsifying medium that becomes the reaction liquid.
It can be prepared by an interfacial polymerization method consisting of 11 steps of conditioning and then heating. Further, a composite wall made of a polyurea resin and a polyamide resin can be prepared by using a polyisocyanate, an acid chloride, and a polyamine, by adjusting the pH of an aqueous medium serving as a reaction solution, and then heating it. Details of the manufacturing method of these composite walls made of a polyurea resin and a polyamide resin, and the composite wall made of a polyurethane resin and a polyamide resin are described in JP-A-58-66948. Such composite-walled shells are particularly suitable for forming toner capsules containing magnetic particles within the core material.

The polymers involved in the polymerization reaction for forming the outer shell resin vary depending on the resin forming the outer shell, but two types of similar polymers are usually used in combination. Examples of such monomer combinations include incyanate groups,
At least one bifunctional compound containing a group selected from the group consisting of a thioisocyanate group, a bistaroloformate group, an acid chloride group, and a sulfonyl chloride group, and water, a polyvalent amine, a polyvalent alcohol, and a polyvalent thiol. ,
Combinations with at least one compound selected from the group consisting of polyvalent amines and polyvalent carboxylic acids can be mentioned.

In the method for manufacturing the capsule toner of the present invention, fine solid particles are dispersed in an aqueous medium in the form of oil droplets in accordance with known techniques. The solid particles are present in a dispersed state in an aqueous medium in which the reaction to form the outer shell of the capsule is carried out, and the encapsulation reaction to form the outer shell is carried out in the aqueous medium in which the solid fine particles are dispersed. There is. It has been determined that solid fine particles are contained or attached to the surface of the outer shell of a capsule toner obtained by separating, washing, and drying the microcapsules obtained by carrying out an encapsulation reaction in such a reaction system. It is estimated that the solid fine particles having the shape m; improve the powder characteristics of the capsule toner.

A specific method for containing or adhering solid fine particles to the surface of the outer shell of the capsule toner is as long as the solid fine particles are dispersed in the aqueous medium in which the encapsulation reaction is carried out. Although there are no restrictions on the dispersion method, for example, by adding water to solid particles using a ball mill or the like to create a dispersion liquid, and adding this to an aqueous solution of a wood-philic polymer compound used as a protective colloid, A method can be adopted in which a core substance, an outer shell forming material, etc. are introduced into this aqueous solution according to a known technique to carry out an encapsulation reaction.

At this time, the amount of the solid fine particles added is 0.01 to 20% based on the total weight of the capsule toner to which the solid fine particles are attached.
It is preferably in the range of % by weight, particularly preferably 0
．． 1-10% by weight.

The solid fine particles used in the present invention are preferably substances that have substantially no reactivity with an aqueous medium and have extremely low solubility in water, and preferably have an average particle diameter of IILm or less.

The above “substances with extremely low solubility in water” refer to 25
It means a substance whose solubility in water at °C is 1 [wt/wt]% or less, preferably 0.1 [wt/wt]% or less.

The solid fine particles that can be used in the present invention are not particularly limited as long as they satisfy the above conditions, but include silicon dioxide (StO2) such as hydrophobic silica,
Metal resistant substances such as tita dioxide (T i O2) and aluminum fermentation (A lz O3), carbon salts such as calcium carbonate, km magnesium, barium carbonate,
Examples include acid salts such as barium sulfate, finely granular carbon such as carbon black, and finely granular polymers such as fluororesin fine granules, and these can be used alone or in combination. .

In this specification, "solid fine particles are contained or stuck to the surface of the outer shell of the capsule toner" means that at least a part of the solid fine particles does not easily detach from the surface of the outer shell of the capsule toner. A typical example of this state is that at least a part of the solid fine particles are exposed to the outside on the surface of the outer shell of a capsule toner. attached or embedded in a dispersed state;
Alternatively, the state in which solid particles are dotted and attached to the outer shell surface, or the state in which they are densely dotted and can be regarded as a film-like state, is defined as 8.
cormorant.

After preparing microcapsules by forming an outer shell around a core material, the microcapsules are 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 varies depending on the heating temperature and the type of core material used. However, the time period is usually chosen from 10 minutes to 48 hours, and more commonly from 2 to 48 hours.
Selected from a 24 hour range.

There are no particular restrictions on the equipment and instruments used for heat treatment, such as electric furnaces, Matsufuru furnaces, hot plates,
Any thermal drying equipment and appliances can be used, such as electric dryers, fluidized bed dryers, infrared dryers, etc.

If desired, metal-containing dyes, charge control agents such as nigrosine, or other arbitrary additives can be added to the outer shell of the capsule toner obtained by the production method 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.

Further, the method for manufacturing the capsule toner of the present invention is disclosed in Japanese Patent Application Laid-open No. 5
7-179860.58-21259.58-6694
8.58-66949.58-66950.58-68
753.58-70236.58-91464.58-
95353.58-100855.58-100856
．． 58-100857.58-100858.58-1
11050.5B-144932, 58-145233
Publications of No. 1, and Japanese Patent Application No. 57-64673.57-175404.57-
189139.58-41960.58-48418.
58-58419.58-57421.58-5742
It is also possible to use it in appropriate combination with the capsule toner and capsule toner manufacturing technology described in patent application No. 2.5B-174898.

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

The powder properties of the capsule toners obtained in the Examples and Comparative Examples shown below are based on the apparent density and tap density of the obtained capsule toners. ) was evaluated.

(Tap density) - (Appearance is density) Compression ratio (%) = - - - - - - - - - ( Tap density ) Here, apparent density means that the capsule toner is Tap density refers to the density measured for the accumulated material obtained by dropping it from a certain height into a container, and tap density is the density measured by placing capsule toner in the same container as above and dropping it from a certain height a predetermined number of times. The density measured after hardening. In addition,
The above apparent density and tap density were measured using a powder tester manufactured by Kaiyo Iron Works.

[Example 1] l-dimethylphenyl-1-phenylethane and l5ap
ar H (trade name, manufactured by Exxon Chemical, N point range is 17
40% of polyisobutyl methacrylate-1 was dissolved in a liquid mixture prepared by mixing an aliphatic saturated hydrocarbon mixture (4 to 189°C) at a weight ratio of 6:5. A dispersion liquid was prepared by taking 9 g of this solution and cross-dispersing 7 g of magnetite magnetic particles (EFT-1000, manufactured by To 11.1 Kogyo ■) therein. Next, a 3=1 (molar ratio) adduct of xylylene diisocyanate and trimethylolpropane as the outer shell material 1
．． 6 g of ethyl acetate solution was mixed with the dispersion to form a liquid.

Separately, add 1% hydrophobic silica (average particle size 0.016
1Lm) was dispersed in a ball mill to prepare 40g of a nt solution.

Secondary liquid at 10'C! The liquid was added dropwise to the mixture and stirred using a high speed homogenizer to obtain an oil-in-water emulsion having an average oil droplet size of about 14 pm.

3 g of a 10% by weight aqueous solution of diethylenetriamine was gradually added dropwise to the above emulsion, and then the pH was adjusted to 1O, and the mixture was stirred at 60°C for 3 hours to complete the encapsulation. Next, this microcapsule dispersion was centrifuged at 500 rpm to remove the resulting supernatant, water for washing fI11 was added, and the microcapsule dispersion was centrifuged again for water washing. Repeat this operation twice to remove methyl cellulose from the liquid phase.
The hydrophobic silica of l& was removed.

This dispersion was spray-dried in a spray dryer under conditions of an inlet temperature of 170° C., an outlet temperature of 110° C., and a spray pressure of 2 kg/cm' to obtain a powdered capsule toner.

This capsule toner was a very smooth and highly fluid powder, and microscopic observation confirmed that most of each capsule particle existed independently.

Table 1 shows the apparent density, tap density and compressibility of the capsule toner obtained above.

[Example 2] The same procedure as in Example 1 was performed except that the same amount of carbon black (manufactured by Mitsubishi Kasei ■, blade name: MA-100, average particle size 0.0221 Lm) was used instead of hydrophobic silica. Encapsulation, washing and spray drying,
A powdered capsule toner was obtained.

This capsule toner was a very smooth and highly fluid powder, and microscopic observation confirmed that most of each capsule particle existed independently.

The apparent density, tap density and compressibility of the capsule toner obtained in Section 2 are shown in Table 1.

[Example 3] Encapsulation, water washing, and spray drying were performed in the same manner as in Example 1, except that the same amount of charcoal calcium (average particle size 0.04 gm) was used instead of hydrophobic silica, and powder was obtained. A capsule toner of the form was obtained.

This capsule toner was a very smooth and highly fluid powder, and microscopic observation confirmed that most of each capsule particle existed independently.

Table 1 shows the apparent density, tap density and compressibility of the capsule toner obtained above.

[Comparative Example 1] A powder capsule toner was obtained by performing encapsulation, water washing, and spray drying in the same manner as in Example 1 except that hydrophobic silica was not used.

Table 1 shows the apparent density, lump density and compressibility of the capsule toner obtained above.

Table 1 Example 1 2 3 Comparative Example 1 Appearance is density 0.515 0.530 0.510 0
．． 445 tap density 0.715 0.728 0.7
19 0.706 Compression ratio ($) 28 27 2.9
37 Comparing with Comparative Example 1, the capsule toners obtained in Examples 1 to 3 are presumed to have fewer aggregates due to aggregation because of their apparent high density, and because of their low compressibility, they have a low cohesive force. is assumed to be weak.

From the a111 constant results shown in Table 1, the state of the obtained capsule toner, and the microscopic observation results, it can be said that the capsule toner obtained by the method of the present invention is a capsule toner with good powder properties.

Claims (1)

[Claims] l. The process includes forming an outer shell around an oil droplet-like core material containing a display recording material and a binder dispersed in an aqueous medium to form microcapsules, and then separating the microcapsules from the aqueous medium, washing, and drying the microcapsules. 1. A method for producing a capsule toner, wherein the outer shell is formed in a water-distributing medium containing fine solid particles dispersed therein. 2. The method for producing a capsule toner according to claim 1, wherein the average particle diameter of the solid fine particles is less than or equal to 1Ii,m. 3゜Solid fine particles are CaCO3, MgCO3, Ba
C03, BaSO4,5i02, T i 02, A l
203. The method for producing a capsule toner according to claim 1 or 2, wherein the solid particles are at least one type of solid fine particles selected from the group consisting of: 203, fine particulate carbon, and fine particulate polymer. 4. The method for producing a capsule i-ner according to claim 1, wherein the outer shell is made of polyurea resin or polyurethane resin. 2. The method for producing a capsule toner according to claim 1, wherein the 5° outer shell is made of a composite wall containing polyurea resin and/or polyurethane resin and polyamide resin. 2. The method for producing a capsule toner according to claim 1, wherein the 6° core material contains magnetic particles.