JPH02285363A - Production of toner for electrophotography - Google Patents

Abstract

PURPOSE:To obtain stable electrostatic chargeability by adding an org. solvent which is a lean solvent of a fixable resin into an org. solvent soln. of the fixable resin dissolved or dispersed with a coloring agent and a charge control agent to the toner. CONSTITUTION:The toner is formed by utilizing the microcapsulation by a coacervation method in the org. solvent. Namely, the coloring agent and the charge control agent are dissolved into the org. solvent which is a good solvent of the fixable resin and the org. solvent which is the lean solvent of the fixable resin is added into this soln. to deposit the fixable resin around the coloring agent and the charge control agent. The org. solvent is then removed. The need for melting and kneading is eliminated in this way and the deterioration of the fixing resin is obviated; in addition, the toner characteristic imparting agents, such as coloring agent and charge control agent, are uniformly dispersed in the fixing resin, by which the stable electrostatic characteristics are obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Application The present invention relates to a method for producing an electrophotographic toner having stable charging characteristics.

(Prior art and its problems) In the field of electrophotography, toner used to visualize an electrostatic latent image formed on the surface of a given photoreceptor usually contains a colorant and a fixing resin. A charge control agent is dispersed therein.

This toner for electrophotography is generally obtained by kneading and pulverizing a fixing resin, a colorant, and a charge control agent, and then classifying the mixture into a predetermined particle size range.

However, in the toner obtained by this method, the coloring agent, etc. is partially exposed on the resin surface, and it is difficult to say that these are uniformly dispersed, making it difficult to obtain stable charging characteristics. There is a problem.

(Means for Solving the Problems) The present invention utilizes microencapsulation using a coacervation method in an organic solvent to produce toner, thereby eliminating the need for dispersants such as surfactants. , succeeded in uniformly dispersing components such as colorants in fixing resin.

That is, according to the present invention, a fixing resin, a colorant, and a charge control agent are dissolved in an organic solvent that is a good solvent for the fixing resin, and then an organic solvent that is a poor solvent for the fixing resin is added to the solution. A method for producing an electrophotographic toner is provided, which comprises: adding a fixing resin to a colorant, depositing a fixing resin around a colorant and a charge control agent, and removing the organic solvent.

(Function) In the present invention, an organic solvent serving as a poor solvent for the fixing resin is added to an organic solvent solution of the fixing resin in which the colorant and the charge control agent are dissolved or dispersed. , the fixing resin is precipitated around the colorant and charge control agent as a nucleus.

By removing the organic solvent in this manner, a toner in which the colorant and charge control agent are uniformly dispersed within the fixing resin can be obtained.

In this method, the toner particle size can be easily adjusted by appropriately setting the dropping rate of the poor solvent and stirring conditions.

(Preferred embodiments of the invention) Tadashi-5 (a) Fixing resin: The fixing resin used in the present invention has the fixing properties and electrodetection properties required for the toner, and has ethylenic unsaturation. A polymer or copolymer composed of one type or a combination of two or more monomers is used.

Examples of such monomers include monovinyl aromatic monomers, acrylic monomers, vinyl ester monomers, vinyl ether monomers, diolefin monomers, monoolefin monomers, etc. It is.

As a monovinyl aromatic monomer, in the formula, R is a hydrogen atom, a lower alkyl group, or a halogen atom, and R2 is a hydrogen atom, a lower alkyl group, a halogen atom, an alkoxy group, an amino group, a nitro group, or a vinyl atom. or carboxy group, monovinyl aromatic hydrocarbons such as styrene, α-methylstyrene, vinyltoluene, α-chlorostyrene,
o+, m-, p-chlorostyrene, p-ethylstyrene, sodium styrene sulfonate, divinylbenzene alone or in combination of two or more, and other monomers mentioned above include the following: Each can be mentioned.

formula, R.

CHz-C-Co-0-R4... (2) In the formula, R3
is a hydrogen atom or a lower alkyl group, and R4 is a hydrogen atom, a hydrocarbon group having up to 12 carbon atoms, a hydroxyalkyl group, a vinyl ester group, or an aminoalkyl group. Acrylic monomers such as acrylic acid, methacrylic acid, Methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, β-hydroxyethyl acrylate, γ -Propyl hydroxyacrylate, δ-butyl hydroxyacrylate, β-ethyl hydroxymethacrylate, γ-aminopropyl acrylate, γ-N-N-diethylaminopropyl acrylate, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate acid esters, etc.

Vinyl esters of the formula, C)l, =CH0-C-R, (3) where RS is a hydrogen atom or a lower alkyl group, such as vinyl formate, vinyl acetate , vinyl propionate, etc.

Vinyl ethers of the formula, C) 12-CH RIG, where R6 is a monovalent hydrocarbon group having up to 12 carbon atoms, such as vinyl methyl ether, vinyl ethyl ether, vinyl-n-butyl ether, vinyl phenyl ether, vinyl cyclohexyl ether etc.

Formula, CHx-C-C-CH-Re (
5) Diolefins, particularly butadiene, isoprene, chlorobrene, etc., in which each of R, , R, , R is a hydrogen atom, a lower alkyl group, or a halogen atom.

formula, CHx thousand CR,.

...(6) In the formula, each of R1° and R11 is a hydrogen atom or a lower alkyl group, monoolefins, especially ethylene, propylene, isoprene, butene-1, pentene-1,4-methylpentene- 1st prize.

(b) Coloring agent; Suitable examples of colorants are:

Black pigments carbon black, acetylene black, lamp black, aniline black.

Yellow pigments yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral leufast yellow, nickel titanium yellow, navels yellow, naphthol yellow S1 banza yellow G1 benzidine yellow GR, quinoline yellow lake, vermanent yellow NCC, tartrazine lake .

Orange pigment red yellow lead, molybdenum orange, permanent orange GTR, pyrazolo orange, palkan orange, indus-threan blue luant orange RK, penzidine orange G1 indus-threan blue luant orange GK.

Red pigment red pigment Red Garla, Cadmium Red, Red Lead, Mercury Cadmium Sulfide, Permanent Red 4R, Lysole Red, Pyrazolone Red, Watching Red Calcium Salt, Lake Red D, Brilliant Carmino 6B, Eosin Lake, Rhodamine Lake B1 Alizarin Lake, Brilliant Carmine 3B, purple pigment manganese purple, fast violet B1 methyl violet lake.

Blue pigments navy blue, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, partially chlorinated phthalocyanine blue, fast sky blue, industhrene blue BC.

Green pigment chrome green, chromium oxide, pigment green B1
Malachite Green Lake, Fanal Yellow Green G.

white pigment Zinc white, titanium oxide, antimony white, zinc sulfide.

Extender pigments Palite powder, barium carbonate, clay, silica, white carbon, talc, alumina white.

These colorants may be blended in the amount contained in the toner resin, and are generally used in an amount of 1 to 30% by weight, particularly 3 to 20% by weight, based on the monomer.

Further, in the present invention, when producing a so-called -component type developing toner, a magnetic material can be used as a colorant.

Such magnetic material pigments include, for example, triiron tetroxide (FesOJ), iron sesquioxide (T-Fe203), iron zinc oxide (2nFe*04), iron yttrium oxide (Y
sFesO+2), cadmium oxide (CdFe1204
), iron gadolinium oxide (GdsFllsQsz), iron copper oxide (CuFe204), iron oxide complex (PbFll+z
Ots), neodymium iron oxide (NdFeOs), barium iron oxide (BaFe+20+e), iron manganese oxide (MnFe*04), lanthanum iron oxide (LaFe03)
, iron powder (Fe), cobalt powder (Go), nickel powder (
Nl) and the like are known, but any fine powder of these known magnetic materials can be used in the present invention.

Such magnetic materials generally have a concentration of 5 to 3'0 per fuser resin.
0% by weight, in particular 10 to 250% by weight.

(8) Charge control agent; Also, as a charge control agent, nigrosine base (CI50
45), oil-soluble dyes such as oil black (CI26150) and spirone black, naphthenic acid metal salts, fatty acid metal soaps, resin acid soaps, metal-containing azo dyes, and the like are used.

This charge control agent is usually 1 to 20% by weight based on the fixing resin.
, in particular in a proportion of 3 to 151i%.

(:) Other compounding agents; Furthermore, in addition to the colorant and charge control agent, a toner characteristic imparting agent such as a release agent may be used in conjunction with the colorant and charge control agent, if necessary.

The mold release agent is used to prevent offset, and for example, low molecular weight polyethylene, low molecular weight polypropylene, various waxes, silicone oil, etc. are used.

The release agent is used in a proportion of 1.0 to 20% by weight, especially 3 to 15% by weight, based on the fixing resin.

Soil: Δ and Takuho In the present invention, first, an organic solvent solution of the fixing resin in which a colorant, a charge control agent, etc. are dissolved or dispersed is prepared using an organic solvent that is a good solvent for the fixing resin. do.

In this case, a dispersant such as a surfactant may be appropriately used if necessary so that the colorant and the like are uniformly dispersed in the organic solvent solution.

There is no particular limit to the amount of organic solvent used as long as the fixing resin is completely dissolved, but if it is used too much, the amount of poor solvent used to precipitate the fixing resin in the subsequent steps will be reduced. There will be a lot of them, so be careful.

According to the present invention, a poor solvent for the fixing resin is then dropped into the organic solvent solution.

The addition of such a poor solvent reduces the solubility of the fixing resin in the system, causing the fixing resin to precipitate.

Examples of suitable combinations of good solvents and poor solvents for the above-mentioned fixing resins are shown in Table 1 below.

The particle size of the toner obtained in the present invention can be easily adjusted, for example, by appropriately setting stirring conditions such as the concentration of the dispersant used in the manufacturing process, the dropping speed of the poor solvent, and the stirring speed during precipitation of the fixing resin. In particular, the toner particles obtained by adjusting the stirring conditions moderately aggregate during resin precipitation to become amorphous particles having an optimum particle size range of about 5 to 20 μm.

The thus obtained toner is subjected to solid-liquid separation and dried to obtain an electrophotographic toner.

This toner is coated with carbon black, hydrophobic silica, etc., if necessary, to form a final toner.

(Effects of the Invention) In the method of the present invention, there is no need for melt mixing at all, so not only is there no deterioration of the fixing resin, but also toner characteristic imparting agents such as colorants and charge control agents are uniformly dispersed in the fixing resin. An electrophotographic toner having stable charging characteristics was obtained.

Furthermore, since this toner is amorphous particles obtained by moderately aggregating individual particles, it also has the advantage of having excellent cleaning properties unlike a spherical toner.

In other words, true spherical toner particles easily scrape through the gap between the blade and the surface of the photoreceptor when being scraped off by the cleaning blade, but in the case of amorphous particles, such scraping is effectively prevented, and the cleaning blade Scraping is done smoothly.

Further, the toner obtained according to the present invention has the advantage that it has excellent moisture resistance because the manufacturing process is carried out in an organic solvent and no aqueous medium is used.

The invention is illustrated by the following example.

(Example) Example 1 Polystyrene 0.157 in xylene 400a+Jl
Weight%, 5PAN80 (manufactured by IC1, trade name 5PAN80) as a surfactant 0.1g, Bontron 5-40 (manufactured by Oriconto Chemical Co., Ltd., tradename) as a charge control agent 0.0157% by weight, as an offset inhibitor 0.02% by weight of low molecular weight polypropylene was added to the reactor and stirred at 700 rpm to uniformly disperse it.

Next, 5 g of carbon black MA-100 (Mitsubishi Kasei, trade name) was added and dispersed uniformly, and the system was heated to 70
While stirring at 0 rpm, 100 g of petroleum ether was added dropwise at a dropping rate of 2.20 g/s, and the stirring rate was further increased to 15
The rpm was changed to 0 rpm, and 100 g of petroleum ether was added dropwise to form a polystyrene aggregate with carbon black as the core.

The resulting aggregate had a toner size with an average particle size of 12 μm.

Using this toner, electrophotographic copying machine DC-2055 (
When an image was formed using a product manufactured by Sanda Kogyo Co., Ltd. (trade name), a clear and good image was formed. Furthermore, 30℃, 85
Similar image formation was carried out at a high temperature and high humidity of 50%, but there was no deterioration of the image, no filming of toner on the photoreceptor, and good cleaning performance.

Claims (1)

[Claims] (1) A fixing resin, a colorant, and a charge control agent are dissolved in an organic solvent that serves as a good solvent for the fixing resin, and then an organic solvent that serves as a poor solvent for the fixing resin is added to the solution; A method for producing an electrophotographic toner, which comprises depositing a fixing resin around a colorant and a charge control agent, and removing the organic solvent.