DE1472988A1 - Toner for electrophotographic purposes - Google Patents

Description

Unitr «sign tag sheet

K 136o SP-Dr.R-eg 8.11.19-62 '■.

description
to register

KAIIl AKTIENGESEIISCHAIO}

Wiesbaden-Biebrieh

for a patent

concerning
Toner for electrophotographic purposes

The "" present invention relates to electrophotographic Toners having a spherical or nearly spherical shape and a process for their production,

As is known, latent electrostatic images are produced in electrophotography by contacting them with finely divided, mostly organic, resin-like particles small grain size and triboelectric properties visible made. These resin-like particles, the so-called toners, adhere according to their electrostatic charge either at the charged points of the latent image or are repelled by them, so that they are discharged Cover places. The relationships here are very complicated and of many factors, some known, some up to now

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K 136o SP-Dr.E-eg November 8, 1962 $

unknown, a "dependent ₀

The desired electrical charging of the toner can be achieved in various ways. ^ü o it has already been suggested that the toner mixed with a carrier particle of larger diameter to form the so-called developer, or brought to the latent electrophotographic image in the form of a cloud of dust or by trickling over it. In any case, the properties of the toner depend on the quality ie the optical impression depends on the copy. Particular attention must be paid to the round line, ie the non-image areas must not show any traces of toner that can be perceived by the eye.

Attempts have been made to meet this requirement by selecting suitable, non-sticking plastics as a basic toner substance and by producing toner particles with the cheapest possible to meet triboelectric properties. However, the toners used heretofore could meet the above-mentioned desires do not meet the mentioned properties, as they due to their non-uniform electrostatic properties and due to their mechanical qualities by a electrostatically differentiated surface, as it is on an exposed, electrophotographic paper,

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not be influenced in a desirable way "

The present invention relates to ions for electrophotographic use "consisting of resins and optionally additives, characterized in that they are spherical or nearly spherical in shape.

Natural, modified natural and synthetic resins are used in IVage as Ha, rg; e ^{of which the ioner according to the invention can consist.} Natural resins are, for example, balsam resins, rosin or shellac. Modified natural resins are, for example, oil-modified phenolic resins and other resins, such as those specified below, with the greatest possible rosin content. In the present case, all plastics known and usable for toner purposes are to be used as synthetic resins, for example polymers such as vinyl polymers, for example polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyvinyl acetals, polyvinyl ethers, polyacrylic and polymethacrylic acid esters, also polystyrene and substituted polystyrenes or polycondensates, e.g. polyesters, such as phthalate resin, terephthalic acid and isophthalic acid polyesters, maleinate resin and rosin mixed esters of higher alcohols, also phenol-formaldehyde resin, especially rosin-modified phenol-formaldehyde condensates,

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Aldehyde, ketone, xylene-formaldehyde resins, polyamides, polyadducts, such as polyurethanes, ^ s come but also · -tolyolefine how various polyethylene, polypropylene, polyisobutylene, chlorinated rubber in question _o

In the present case, we understand additives essentially Dyes and color pigments. These should make the toner more visible through coloring. Also serve they sometimes also serve to influence the sense of charge of the toner in a known manner

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In principle, all compounds such as those mentioned in the Color Index, Vol. I and II, Second Edition, 1956, can be used as dyes, in particular Fettschwarz HBN (C ₀ Ie No. ₀ 26 15o), Nigro are soluble in fuel (CI, No. 5o.415), Sudantiefschwarζ BB (Solvent.BLack 9), Ohromögschwarz ETOO (C ₄ I. Nr. 14 645), Azo Oil Black (Solvent Black 12), Josol Black (Solvent Black 13), ^z aponschwarz X (Farbw. Hoechst AG-), Ceresschwarz ^ 'G ^ Farbenfabrik Bayer AG), and also mixtures of such dyes and / or pigments. It is also, often expedient, to add small amounts, for example 0.1 to 10 #, preferably 1 to 5 #, to the toners, waxes or low- melting organic compounds and their substitution products

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add in order to "influence the melting point and the adhesiveness of the toner mixture in the desired manner". Other additives include "fillers, pigments, e.g. Hüss or aniline black or stabilizers in Question how they are used in known ways for these purposes will"

Another object of the invention is a process for the production of said toners, characterized in that that the components of the toner in a solution and / or "Dissolved" dispersant or dispersed, sprayed and by subsequently heating the sprayed material from the liquid "to be freed.

The inventive toners "have" preferred properties; their spherical shape means that the particles only develop a point-like contact on the surface. The electrophotographic paper and therefore have a high degree of mobility; they will therefore be able to follow the influence of the electrostatic forces of the latent image in an ideal way, since their mobility is not hindered by corners and edges or by any other uneven formation of their surfaces also has the consequence that they also have the light-discharged areas with which they are fully in from the start

Be brought into contact, can easily be left again. 909819/0924

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This results in image-free areas that do not match the Have more traces of toner perceptible to the eye. Perner is by the same radius of curvature, which is present at every point of the individual particle, the electrical charge so evened out that no M or polypolar particles can appear, which are mutually charged or uncharged areas of the electrophotograph! see layer to visit in the - ^ age are

Furthermore, the equalization of the electrostatic properties is also expressed in terms of the charge level of the individual toner particles, i.e. the spread of the charge level "of the individual Toner particles kept within very narrow limits. As a result, there are practically no toner particles on the residual charge respond more at the exposed areas of the photoconductive layer. Through this laktor, the far-reaching The fundamental freedom of the image developed with the toner according to the invention is also determined.

In the following the invention on the basis of a principle Examples of the production of the toner include the following Are explained in more detail:

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Io selection of the components of the solution or dispersion taking into account the heart-forming particles,

2. H _ers tellung the solution or dispersion,

3 ο spraying the solution

4 »the drying,

5. the deposition ·

The choice of the components of the solution or dispersion should be considered in general according to two points ":

a) the carrier of the phase property, ie. the solution

or dispersants and
Ta) the grit to be dried, "consisting of resins and 'if necessary additives"

Essentially organic liquids come into consideration as solvents and dispersants they should desirably not possess low boiling point, such as below ¹ ^ o ⁰ O ■, but as small as possible TercLamp ^ fungswäriiie having ^first Ss has been found to be beneficial; Above all, using liquids that are not flammable \ otherwise a protective gas would have to be used. It is further desirable, -that a selection of the solvent 'is ^^ ^ ahingehend made that all components of the toner material, except as the pigment additives therein are readily soluble ₀

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Particularly favorable results are obtained when using halogenated, saturated or unsaturated, low Hydrocarbons. Also mixtures of these solvents respectively Dispersants are for the present purpose good to use.

Solvents and dispersants to be used according to the invention include straight and branched, saturated and unsaturated hydrocarbons with hydrocarbon chains of about 5-11 carbon atoms, such as pentane, pentene, iso-hexane, dimethyloctene, saturated and unsaturated cycloaliphatic ones Hydrocarbons, such as cyclopentane or ^u yclohexane, aromatic ^ erbungen such as benzene, toluene, xylene, mesithylene, also substituted aliphatic and aromatic hydrocarbons, especially chlorinated hydrocarbons with low carbon chains, such as methylene chloride, the various commercially available ethylene chlorides, fluorinated hydrocarbons and compounds with H hydrocarbons, eg ^A ther as ethyl, '· ether, ^ iäthyläther, or tetrahydrofuran, dioxane, esters, such as of monobasic and polybasic alcohols with mono- or polybasic acids, eg Essigeeter, Glykoleeter uswl, ketones such as acetone, ethyl Metliyl ketone containing nitrogen end compounds, such as ^ ormamid; also liquefied gases are BEZW in the present case. Procedure applicable.

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The goods to be dried can consist of the resins and additives as described in detail above. Palis it is desired can be added to the G-ut to be sprayed also inorganic, finely powdered material, such as which has magnetically excitable properties, e.g. «, finest powder made of iron or magnetite or glass dust can be added.

In the preparation of the solutions respectively. Dispersions should it can be assumed that only such a concentration is used that the viscosity of such solutions cannot affect the sprayability. Very favorable results were obtained when spraying a solution with a viscosity between 2 and 8 cp «achieved; however, those with a viscosity between 1 and 15 o.p. and even those up to viscosity from 5o c.p. applicable. In the normal case one corresponds to Viscosity of the preferred type specified, a concentration between 1 and Io G-ewichts- ^ of the solid, based on the total weight of the solution or Dispersion.

The preparation of the solution itself can be done in a known manner, can be done by stirring with or without heating * The Persistence of the BispersioB should watoen, until their later revision has ended ”.

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The solution can be sprayed from one or more one or two-fluid nozzles. So-called mixing nozzles can also be used. JSs must also ensure that these result in a defined degree of atomization. Normally, at a pressure between Io and 5o kgf / cm to work, but is in "special cases a higher or lower pressure of Yorteil. ^ He Düsendurch- W knife, the pressure and viscosity" have a certain influence on the average particle size and on the throughput quantity »This generally means that with a smaller diameter and higher pressure a smaller particle diameter of the sprayed material results» Particularly good results are achieved when using a separating current radiation spray drying process according to patent _o

(Patent application * - 47 951 X / 82a).

y The drying, i.e. the liberation of the dissolved and diaper-

gated solid from the solvent or dispersion medium can be effected in various ways In general, the following G-esichtpunkts decisive:

The heat output of the heat source * ζ, Β "-from infrared radiators" the M _e length of the supplied Irägergases, for "B. of the air, the throughput rate, the constants of the solvent components, such as boiling points and heat of vaporization »

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It should be noted that the heating power is sufficient to completely evaporate the solvent within the heating zone. When dimensioning the tightness of the carrier gas, it must be ensured that it is sufficient to convey and separate the dry material. ^ö ie must also be sufficient to provide a feedback of the solvent evaporate in the dry material to prevent, for example, in the form of a Wiederanquellung and resultant subsequent deformation of the particles.

The throughput speed and the material yield per hour is determined by the choice of nozzle and the spray pressure and the number of nozzles. In general, good results have been achieved with throughput, which is yield corresponds to from loo to looo g dry matter per hour and nozzle, however, larger quantities can also be achieved with good quality of the desired end product.

The material constants of the solution are: The heat of evaporation and the boiling point of the solvent, the specific ^ * poor of the "main products and additives" As an apparatus for drying the sprayed particles the aforementioned separating current radiation spray dryer is preferably suitable. This has compared to the usual hot air dryers the merit that the solvent fumes

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which can change the nature of a casing, can be removed almost quantitatively from the dry material. As a final product a completely dry, free-flowing powder is obtained according to the invention. The yield is close quantitatively.

The inventive method is advantageously obtained toner particles which have a very narrow grain size distribution, for example between 2 and 2o / u or between 5 and 25 / u. If it is for special cases If it is desirable, the center of gravity of the grain size can also be shifted upwards, for example up to 3o, 4o or 5o / u <> Desirably, the invention the The limits of the size spectrum kept sharp; it is therefore an additional sifting or separation of individuals Fractions are no longer necessary due to relatively complex procedures.

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Example 1; .

loo g maleinate resin (Hobimal ^ 'P 59) »loo g polystyrene üß, Io g nigrosine aprit-soluble are dissolved in 3ooo ml trichlorethylene at room temperature and in this solution Io g Euss (Peerless Black) and 5 g pigment deep black suspended with vigorous mixing, what a solution of 5 g by weight corresponds to solids. This mixture is at a pressure of 3o kp / om by a "circ ^ll - ^ e'beldüse of o pressed 35 mm diameter and sprayed into an infrared radiation field, which is generated from 9 radiators with about 5 kW total power As ürenn. - and separating medium, about 4oo obm air per hour from room temperature needed about 8o obm with solvent vapor laden ^"A BlAir per hour is drawn off, the discharge temperature of the solvent-free dry material is about 4o ° O. ^ m cyclone separates out about 9o $ the set. Pesticide, which consists entirely of whole spheres with particle sizes between 2 and -2o / u.

A toner produced in this way is now either mixed with a carrier, for example iron powder or glass beads, for use for electrophotographic purposes, or, as a ^two -component toner, an approximately equal amount of a finely divided powder, for example kieselguhr, is added. It can now be used in a conventional electrophotographic process for visualizing an electrostatic latent image

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This results in ground-free images with great hand sharpness, which has a desirable power to deceive the image areas demonstrate.

Example 2;

Ho g chlorodiphenyl resin, 90 g polystyrene IG, 12 g fat black HBN (C.I, 26 15o) and 2 g Geresschwarz ^^ · ("iärienfabrik Bayer AG ·) are in 28oo ml of 'trichlorethylene to "a'r Weight of solution dissolved. By condemnation, '

as in Example 1 and drying in infrared Strahlungsfeia of 12 emitters are obtained with about 6.4 kW total power * "at the same air flow rate and about loo cm- lösungsmitteibeladener exhaust air per hour in the cyclone a solvent-free toners of about 85 i ° yield, ^ he The toner obtained in this way is mixed with the same amount of kieselguhr and used to make a latent, electrostatic image visible. Eye no more traces of toner ^r "noticeable ■" - ' ■ ■■■■■■'" ^:

Example 3 t '"- ^: ■■■■ - ■ - ·' · ■ - ■ -'- ■ ■" ■■ '■ ■ "^; ■ - ■ · - ^: '" ■ '■ ^: ~~ * ■ '■ -'- ■ ^{/ s} 47o <G-' parts by weight of an Ölfröien alkyd resin with 'the weight ⁸ number 8o- --9o and the' ^: -melting point 63 - 8ö ⁹ 'G ^ Phteö ^ p are in V5oo " Divide by volume; Me ^ hylenOhl- or'id dissolved. Mari-

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mixes the solution with a second solution, the 47o parts by weight of a maleinate resin with an acid number of 2o - 25 and the melting point 95 - lo5 ° C (Beckacite ^ 'K Io5) and 6o Parts by weight of the dye Azo Oil Black in trichlorethylene contains, and diluted with .Trichlorethylene to a total volume of 50,000 parts by volume. The mixture is sprayed under a pressure of 25 kp / cm with a nozzle o.35 mm in diameter. The one for drying The necessary heat is supplied by 9 infrared heaters, which are operated with 6 kW. The ioner collected in the cyclone consists of spherical particles.

In a mixture with iron powder (particle size 15o - 3oo microns) the toner develops negative charge images to clean, ground-free reversal images

Example 4- »

Dissolve 2o parts by weight mentioned in Example 3 maleate, 2o ^& ewichtsteile a Ohlordiphenylharzes with the softening point 6o - 7o ° C (Olophenharz ^ W), 2o Gewiohtsteile polystyrene IG, 3 parts by weight of the dye Azo Oil Black, and 3 weight parts of the dye

(R)
Ceres black ^v 'S in trichlorethylene. To this is added a solution of 4o G _e vrichtsteilen mentioned in Example 3 alkyd resin in 2oo volumes of methylene chloride and

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f sprays the mixture under the same conditions as in

f, 'Example 3 given. Developed over preserved! Eoner

J; to f in mixture with iron powder, a negative charge image a clean, free base ümkehrbildo

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Claims (2)

KALLE AKTIENGESELLSCHAFT ^ ₇₂₉₈₈ * 'Our signs - day sheet (C X3iü 3P-Dr.E-ef 8.11.X962 P m t · ntaneprüohs phone for electrophotography 2 purposes, existing made of harsen and possibly ucatsen, thereby kean-lehnet, that they have a spherical or almost spherical shape, 2. A method for the production of toners for electrophotographic purposes according to claim 1. characterized gekennztiohnet that the components of the ioners in a solution and / or dispersant dissolved besw. dispersed, are sprayed and freed from the liquid by subsequently swirling the sprayed material. ACT IJSHGESE1L3 CHAPT 0 9 819/0924