CH645197A5 - Toner powders for the development of electrostatic images - Google Patents

Description

The invention is illustrated by the following non-limiting examples.

Example I

164 g of 4-a, a-dimethylbenzylphenol, 526 g of "Epikote" type 1001 (Shell), 0.3 g of tetramethylammonium chloride and 60 g of carbon black ("Printex" -G, Degussa ) mixed. During the homogenization, the temperature was raised to 200 ° C and then left at that value for 60 min. The blocking reaction of the epoxy resin was completed at this point and the low molecular weight portion of the toner was ready. Then 250 g of phenoxy resin "Rütapox" type 07-17 (Bakelite) were added as a higher molecular fraction and the mixture was homogenized for a further 150 min. After cooling to room temperature, the mixture was ground and classified. The particle size distribution of the resulting toner powder was 6-30 (im, the specific area 0.42 (im "" 1.

The glass transition temperature (Tg), measured with a thermal analyzer from Du Pont, type 990, was 58 ° C. The molar epoxy mass (EMM) was 9100 and the residual proportion of monofunctional phenol was less than 0.1%. The melt viscosity at 140 ° C., measured in a mechanical spectrometer from Rheometrics, Inc. with cone and plate, was 210 s-Pa.

Three parts of this toner powder were mixed with 97 parts of oxidized iron powder ("Fer-mag" MTM Brunito; Tinioli, Italy). This developer was charged by stirring in a developer unit, the toner taking on a charge of -19 \ iC / g. The developer was used to develop a positively charged latent image on a selenium type photoconductor. The image was transferred electrically to normal paper and melted under the influence of heat. A good copy has been received. Large, contiguous black areas of an original artwork could be copied with a high and uniform density of the corresponding areas on the copy without the so-called edge effect. The toner could be fixed in a thermal contact melting system used for test purposes at temperatures between 68 and 114 ° C (melting range width 46 ° C). The melting system worked with a contact time of 1.3 seconds between the heated roller and an A4 copy sheet.

Example 2

s A commercially available, negatively charged toner based on an a-methylstyrene / butyl acrylate copolymer was tested under exactly the same conditions described in Example 1. The glass transition temperature (Tg) of this toner was 55 ° C. The toner could be fixed on plain paper at temperatures between 88-131 ° C corresponding to a melting range of 43 ° C. The distance between the Tg value and the lower limit of the melting range of this toner is accordingly considerably larger than that of the toner of Example 1.

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Example 3

The procedure of Example 1 was repeated, but with 350 g of "Epikote" type 1001.88 g of 4-a, a-dimethylbenzylphenol and additionally with 0.1 g of tetramethylammonium chloro-2o rid as a catalyst. After 45 minutes, a second portion of 0.1 g catalyst was added. After a reaction time of 90 min, the low molecular weight portion was ready. The residual 4-a, a-dimethylbenzylphenol was below 0.1% and the EMM was 4470, indicating that approximately 88% of the epoxy groups had been blocked for 2s.

A higher molecular weight fraction was produced in a Z mixer by reacting 455 g of "Epikote" type 1009 (EMM = 3000) with 34 g of 4,4'-isopropylidenediphenol. Tetra-30 methylammonium chloride was used in catalytic amounts (0.2 g). After a reaction time of 2 hours, the low molecular weight fraction prepared as described above and 73 g of carbon black were added and mixed in thoroughly. The Tg was 67 ° C, the EMM 10 900 35 and the melt viscosity at 140 ° C was 1600 s-Pa.

A toner powder produced from this mixture showed an electrostatic behavior which was as good as that of the product of Example 1. The melting range was between 82 and 135 ° C. (Range 53 ° C).

40

Example 4

A low-viscosity toner was obtained by mixing and reacting 601 g of “Epikote” type 1001, 151 g4-a, a-dimethylbenzylphenol and 0.3 g of tetramethylammonium chloro-45 rid over 90 minutes at 150 ° C., adding 60 g of carbon black and then Addition of 188 g of 4,4'-isopropylidenediphenol-propylidene oxide fumarate polyester with an acid number of 15 (“Atlac” type 382E, Atlas Company) was prepared with a mixing time of 2 hours. The Tg was 47 ° C, the EMM 8500 so and the melt viscosity at 140 ° C was 7 s-Pa. The melt was ground and classified. The resulting toner powder could be charged triboelectrically with negative polarity against the oxidized iron powder from Example 1 up to charges of -27 | xC / g.

55 The toner was easily fixed in a radiant heating system on normal paper.

Example 5

Following the procedure of Example 1, a toner was made from 60 48.9 g of "Epikote" type 1001 (EMM = 495), 12.1 g of benzoic acid as a modifier, 6 g of carbon black and 33 g of phenoxy resin ("Rütapox", type 07-17 ) produced. A thermally stable toner powder with the following properties was obtained: melt viscosity (140 ° C.) = 600 s-Pa, Tg value = 6S 61 ° C., EMM = 35,000. The toner could be negatively charged against a technically obtainable iron carrier powder and can be fixed both by radiation and by contact heat.

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645197

Example 6

A mixture of 450 g of "Epikote" type 1004 (EMM = 900), 111.2 g of p-toluenesulfonanilide as a modifier and 35.8 g of carbon black was mixed at 200 ° C. for 3 hours. The mixture showed a Tg of 72 ° C, an EMM of 18,000 and a melt viscosity (140 ° C) of 85 s-Pa. The resulting toner powder was thermally stable and could easily be fixed on paper by heat.

Example 7

A mixture of 25.3 g of "Epikote" type 828 21.7 g4-a, a-dimethylbenzylphenol, 0.5 g of tetramethylammonium chloride and 6.0 g of carbon black was heated to a temperature of about 180 ° C. in a container provided with a stirrer and oil bath heating and kept this temperature for 90 min. The reaction mixture showed an EMM value of 3800.88% of the starting epoxy groups had been converted. The reaction mixture was mixed with 46.5 g of “Epikote” type 1009 (EMM value = 3150) and the mixture was stirred at 200 ° C. for a further 90 minutes.

The melt was poured off and cooled to room temperature. The solid mass was ground and sieved in a known manner to give a toner powder with a particle size between 8 and 24 µm. The toner had a Tg of 51 ° C and an EMM of 4100. About 82% of the starting epoxy groups (which were present in the "Epikote" type 828 and 1009 products used as starting resins) had reacted.

The use of a liquid epoxy resin with a

EMM of less than 500, and preferably less than 250, as the starting epoxy resin for making the modified resin, as explained in this example, has the important advantage that a toner powder with a Tg 5 of about 50 ° C and a melting range is obtained which begins just above the Tg temperature without the need for an auxiliary such as N-cyclohexyl-p-toluenesulfamide, as described for this purpose in the applicant's Dutch patent application No. 7415325. The auxiliary has the disadvantage that it tends to migrate out of the toner powder and to deposit on the carrier particles and / or the fusing rollers of the fixing system. It therefore adversely affects the charging properties of the toner powder and the durability of the fusing rollers.

When used in an electrophotographic copying machine with a contact melting device, the rollers of which were coated with silicone rubber and provided with a thin layer of silicone oil, the above toner powder could be fixed excellently with an effective contact time of 0.03 sec and a temperature of the contact roller of 165 ° C . In order to fix a technically available toner powder based on styrene / butyl acrylate copolymer in the same period of time, the temperature of the contact roller would have to be 210 ° C., which is less desirable in terms of heat loss and energy efficiency.

If a toner powder according to the invention is to be used for high-output electro-photocopiers, it is therefore very advantageous to use a liquid epoxy resin as the starting material for the production of such a toner powder.

C.

Claims (23)

645197 PATENT CLAIMS 1. Heat-fusible, negatively chargeable toner powder for the development of latent electrostatic images, which powder contains finely divided toner particles containing an insulating thermoplastic resin and coloring material, characterized in that the insulating thermoplastic resin consists predominantly of: a modified resin, which is a derivative of an epoxy resin or several epoxy resins, in which or in which at least 50% of the starting epoxy groups (a) partially and at least 5% by chemical reaction with a monofunctional carboxylic acid, a monofunctional phenol or N-arylarylsulfonamide and (b) partly by reaction with the hydroxyl groups of the epoxy resin or epoxy resins or / and are blocked by reaction with a difunctional or polyfunctional epoxy hardener, and that the toner powder at 140 ° C has a melt viscosity between 2 and 200,000 s-Pa and also a glass transition temperature between 45 and 8 5 ° C. 2. Toner powder according to claim 1, characterized in that the modified epoxy resin is at least 20% by weight a derivative of a liquid epoxy resin with a molecular weight of at most 500, the epoxy groups of 50-95% by chemical reaction with a monofunctional carboxylic acid, a monofunctional Phenol or N-aryl-arylsulfonamide and 5-50% blocked by intermolecular reactions and, if desired, by reaction with an epoxy hardener. 3. Toner powder according to claim 1 or 2, characterized in that the epoxy groups of the epoxy resin or epoxy resins, from which or which the modified epoxy resin has been derived, are blocked to such an extent that the total mass of the components (1) and ( 2) has a molar epoxy mass of at least approximately 8000. 4. Toner powder according to claim 1, 2 or 3, which is particularly suitable for fusing by radiation, characterized in that the viscosity of the toner powder, measured at 140 ° C, between 2 and 1000 s-Pa and its glass transition temperature between 45 and 65 ° C lies. 5. Toner powder according to claim 4, characterized in that at least 50% and preferably at least 70% of the epoxy groups of the epoxy resin or epoxy resins, which or which has been or are used as the starting material, by chemical reaction with a monofunctional carboxylic acid, one monofunctional phenol or N-aryl-arylsulfonamide are blocked. 6. Toner powder according to claim 1, 2 or 3, which is particularly suitable for fixing by contact melting, characterized in that the viscosity of the powder measured at 140 ° C between 200 and 200,000 s-Pa and its glass transition temperature between 45 and 80 ° C. lies. 7. Toner powder according to claim 6, characterized in that 10-35% of the epoxy groups of the starting epoxy resin or the starting epoxy resins are blocked by chemical reaction with a monofunctional carboxylic acid, a monofunctional phenol or N-aryl-arylsulfonamide, while the remaining epoxy groups are blocked up are blocked to a total of at least 50% by intermolecular reaction with the alcoholic hydroxyl groups of the resin itself. 8. Toner powder according to claim 6, characterized in that at least approximately 40-75% of the total number of starting epoxy groups of the starting epoxy resin or of the starting epoxy resins mainly by chemical reaction with a monofunctional carboxylic acid, a monofunctional phenol or N-aryl-arylsul-fonamide and only to a lesser extent through intermolecular Reaction and 25-60% blocked by reaction with an epoxy hardener. 9. Toner powder according to one of the preceding claims, characterized in that the monofunctional 5 carboxylic acid is a substituted or unsubstituted. 10. Toner powder according to any one of claims 1-8, characterized in that the monofunctional phenol is a phenol which io substituted with one or more alkyl, aralkyl, cycloalkyl, aryl, alkylaryl, alkoxy or aryloxy groups and under the conditions of the blocking reaction is practically non-volatile. 11. Toner powder according to claim 10, characterized in that the monofunctional phenol is 4-a, a-dimethylbenzyl) phenol. 15 12. Toner powder according to any one of claims 1-8, characterized in that N-aryl-arylsulfonamide is the p-to-luenesulfonanilide. 20th Both two-component and one-component developer based on toner powder containing toner particles, which in turn contain an insulating thermoplastic resin 25 and coloring material, are generally used for the development of latent electrostatic images, e.g. can be obtained on a suitable support by electrographic or electrophotographic processes. The latent electrostatic images can have a positive polarity, as is the case, for example, with electrophotographic elements based on selenium, or a negative polarity, as is the case, for example, with zinc oxide-based electrophotographic elements or based on a number of organic photoconductive compounds 35 is Examples of insulating thermoplastic resins that have been proposed for use in toner powders are polystyrene, copolymers of styrene with an acrylic acid reester and / or methacrylic acid ester, polyamides, phenol-4o formaldehyde, polyester and to a lesser extent epoxy resins. The color material used in black toner powders for use in a two-component developer is mostly carbon black (carbon black), while the color material of black toner powders intended for use as a one-component developer generally consists predominantly of finely divided magnetic material, such as e.g. Iron powder, chrome oxide or nickel ferrite. For colored toner powders, e.g. For use in multicolor reproduction processes, organic dyes are usually added to the thermoplastic resin. When developing a latent electrostatic image, the toner powder is deposited on the charged parts of the image, creating a visible image. One-component developers can be used to develop electrostatic images with positive polarity or to develop such images with negative polarity without the need for special precautions. For two-component developers, the carrier 60 to be mixed with the toner powder must be selected so that the toner powder takes on the desired triboelectric charge. Examples of commonly used carriers are iron, nickel, metal oxide, glass, sand or quartz particles of the desired particle size. If desired, the particles can be provided with a polymer coating. Negatively charged developers are mostly used for the development of electrostatic images with positive polarity 3 645197 used, while positively charged developers mainly powder much closer to the glass conversion for the development of electrostatic images with non-temperate than is currently the case with the negative polarity. For the development, used toner powder is the case. the toner powder on the charged latent image areas - The triboelectrically negatively charged heat-stored, whereby a visible image is created. 5 contain fusible toner powder according to the invention The powder image formed with either the one-component developer or meltable particle that forms a thermoplastic resin-compatible two-component developer can be fixed component, color material and, if desired, a negative directly on the surface on which it contains deposited polarity control agent; they have been made, e.g. in the so-called direct elec-, that the thermoplastic resin component is the case of photographic photography. In the so-called indirect 10, for the most part and preferably completely, electrophotography, the powder image is made to a suitable residue: Transfer zeptorblatt and subsequently fixed on this. (1) a modified resin which is a derivative of a The fixation is usually carried out by the action of heat, nem or more epoxy resins, of which or which e.g. In so-called radiation or flash melting devices, at least 50% of the total number of the original or in the so-called contact melting devices, in which 15 epoxy groups are blocked, (a) partially and at least the powder image with a heated surface in contact at least 5% by chemical reaction with a monofunk brought, e.g. a roller and / or a belt. tional carboxylic acid, a monofunctional phenol Apart from the above-mentioned components, ent- or N-aryl-arylsulfonamide, and (b) partially by reactive often hold the toner powder another known tion with hydroxyl groups of the epoxy resin or the epoxy Component or several known components, in particular resins and / or by reaction with a bifunctional special plasticizer and polarity control agent. or polyfunctional epoxy hardener, and if desired The basic requirements to which a toner powder for (2) a phenoxy resin, the components (1) and satisfactory results should correspond, can be cross-linked (2) with one another, the toner powder embossed polarity, good charging properties, such as sufficient a melt viscosity measured at 140 ° C of between 2 appropriate charge capacity, uniform charge distribution, 25 and 200,000 s-Pa and a glass transition temperature Has charge stability and low sensitivity to moisture between 45 and 80 ° C. Activity and temperature, good and reproducible melt set- To meet the requirement that the toner powder properties, thermal stability and good durability- according to the invention under normal storage and Ver-keit with prolonged use. In order to save melting energy, the turning conditions should be stable, at least 50% of the time, it is mostly still desirable that the temperature, 30 total number of epoxy groups in the starting epoxy at which the toner powder begins to melt, be so close to resin or the starting epoxy resins in the above indicated as possible above the minimum value of the glass-encased way. What percentage of the gel temperature is, which minimum value for the thermal total number of epoxy groups in the starting epoxy resins see stability of the powder is necessary; Generally, in order to achieve the desired stability, this transition temperature should be between 45 and 80 ° C. At 35 depends on the reactivity of the starting epoxy ear. Toner powder for contact melting is also desirable. The higher the reactivity of the starting epoxy resin, the greater the melting range being as wide as possible, or the starting epoxy resin, i.e. the lower the so-preferably several ten degrees. This is intended to minimize the molar epoxy mass of the starting epoxy resin or the possibility that part of the powder-forming resin is or are, the higher the percentage of the melt roller and from it back to the Pa portion of the blocked epoxy groups lying around to get a stable pier is transferred, which creates so-called "ghosting" toner powder. As a molar “epoxy mass”, the melting rollers are contaminated. The resin mass in grams, which contains one gram equivalent of the lower limit of the melting range, is the lowest temperature epoxy (see page 4-14 "Handbook of Epoxy Re-tur, at which the image is just sufficiently fixed; sins", Lee and Neville, McGrawhill Company, 1967). The upper limit of the melting range is the temperature, for the sake of brevity the molar epoxy mass will begin to appear as "ghosting" in the following. Denoted “EMM” value. Preferably, the epoxy groups of the starting epoxy resin or resins in such an object of the present invention are toner powder that blocks at bulk that the EMM value of the total mass of triboelectric contact with metal carrier particles is a ne component (1) and (2) in the Assume toner-negative charge according to the invention, under normal storage and so powder is at least 8000. For some of the commercial conditions of use are highly stable and in the most readily available technically available epoxy resins, hem degrees are the desirable properties indicated above - in the following table they have the mean EMM values and the shade of toner powders. Another goal of the inven- tion percentage of the epoxy groups of the resins specified is that toner powder with a lower glass conversion - which must be blocked in order to increase the EMM values of the temperate - at which the lower limit of the melting range 55 resins to a predetermined higher value bring to. table «Epikote» percentage the blockie type: 828 1001 1004 1009 rank 0 middle EMM 190 500 900 3200 50 do. do. 380 1000 1800 6400 75 do. do. 760 2000 3600 12850 87.5 do. do. 1520 4000 7200 25600 93.75 do. do. 3040 8000 14400 > 50000 96.87 do. do. 6080 16000 28800 98.43 do. do. 12160 32000 > 50000 645 197 4 From the table above it can be seen that in an "Epi-kote" type 1009 only a little more than 50% of the epoxy groups of the resin have to be blocked in order to achieve a resin with an EMM value of approximately 8000, whereas in the case of a low molecular resin type generally at least about 87.5% of the epoxy groups of the resin must be blocked for this purpose. It should also be noted that in the case of the low molecular weight epoxy resins, an increase in the EMM value by a few thousand actually corresponds to only a few percent increase in blocked epoxy groups. It is therefore readily understandable that the condition that the EMM value of the total mass of components (1) and (2) in the toner powder is preferably at least 8000 is less stringent, the lower the molecular weight of the starting resin. Although the sensitivity of the EMM value as a measure of the reactivity remaining in the thermoplastic resin apparently decreases with decreasing molecular weight of the epoxy resin used as the starting material, 20 the applicant assumes that the EMM value is still the best measure currently available for this. The modified epoxy resins used in the toner powders according to the invention can be produced in a particularly economical manner from technically or commercially available epoxy resins. Mixtures of such resins can also be used. “Epoxy resins” are understood here to mean condensation products of a polyphenol, in particular 4,4'-isopropylidene diphenol, with a halohydrin, in particular 1-chloro-2,3-epoxypropane. As is known, technically available epoxy resins mostly have EMM values of less than 4000. Examples of epoxy resins which are suitable as starting material for the production of the modified epoxy resin which is used for 3 seconds in the toner powder according to the invention are “Epikote” type 1001 (mp 60-70 ° C., EMM 450-500, both values from the manufacturer), «Epikote» type 1004 (mp 90-100 ° C, EMM 850-940), «Epikote» type 1006 (mp 115-125 ° C, EMM 1550-1900, «Epikote» type 1007 (mp 40 120-130 ° C , EMM 1700-2050) and "Epikote" type 1009 (mp 140-155 ° C, EMM 2300-3400). Mixtures of two or more epoxy resins can also be used. For certain purposes it may be advantageous to use a liquid epoxy resin as Use raw material, as explained 45 below. The choice of the blocking method or the combination of blocking methods according to the above information is related to the type of fixing intended for the toner powder. It was found that when the toner powder according to the invention is to be heated or fixed with radiation for melting, the viscosity of the toner powder, measured at 140 ° C., advantageously between 2 and 1000 s-Pa and its glass transition temperature (in the following Tg designated) should be between 45 and 65 ° C. 55 For use in a contact melting plant, the viscosity of the resin at 140 ° C should preferably be between 200 and 200,000 s-Pa and its Tg value between 45 and 80 ° C. Blocking by means of a monofunctional carboxylic acid, a monofunctional phenol or N-aryl-arylsulfonamide leads to the desired increase in the EMM value of the starting epoxy resin without a substantial increase in molecular weight and viscosity. This blocking method should therefore have been applied to modified epoxy resins which are intended in the toner powder according to the invention for use in a jet melting plant. The above parameters for viscosity and Tg- Radiation fixation values of a preferred toner powder according to the invention are generally obtained when at least 50% and preferably at least 70% of the starting epoxy groups of the modified epoxy resin or the mixture of epoxy resins are blocked by chemical reaction with a monofunctional carboxylic acid, a monofunctional phenol or N-aryl-arylsulfonamide are, only a minor part, e.g. 5-10%, is blocked by intermolecular reaction and preferably no epoxy groups are blocked by reaction with an epoxy hardener. The monofunctional carboxylic acids, phenols or N-aryl-arylsulfonamides which can be used in connection with the invention should have, apart from the carboxyl, hydroxyl or sulfonamide groups which are characteristic of such compounds, no further substituents which, under the reaction conditions prevailing during the blocking step, with the epoxy groups of the starting resin can react. Both aliphatic and aromatic carboxylic acids can be used as the carboxylic acids for blocking. Suitable aliphatic carboxylic acids include heptanoic acid, nonanoic acid, dodecanoic acid and isododecanoic acid, hexadecanoic acid and octadecanoic acid. Good results are also obtained with aromatic carboxylic acids which are optionally or preferably substituted with at least one alk-yl, aralkyl, cycloalkyl, aryl, alkylaryl, alkoxy or aryloxy group and are practically non-volatile under the conditions of the blocking reaction. Examples of such aromatic carboxylic acids are benzoic acid and substituted benzoic acids, e.g. 2,4-dimethylbenzoic acid, 4- (a, a-dimethylbenzyl) benzoic acid, 4-phenylbenzoic acid, and 4-ethoxybenzoic acid. Further examples are the per-fluorocarboxylic acids, e.g. Perfluorobutyric acid, perfluoro-octanoic acid and perfluorodecanoic acid. Suitable phenols for the blocking are in particular those phenols which are substituted with at least one alkyl, aralkyl, cycloalkyl, aryl, alkylaryl, alkoxy or aryloxy group and are practically non-volatile under the conditions of the blocking reaction. Examples of such phenols are 4-n-butylphenol, 4-n-pentylphenol, 2,3,4,6-tetrameth-ylphenol, 2,3,5,6-tetramethylphenol, 4- (a, a-dimethyl) -benz- ylphenol, 4-cyclohexylphenol, 3-methoxyphenol, 4-meth-oxyphenol and 4-ethoxyphenol. Examples of suitable N-aryl-arylsulfonamides are benzene-sulfonanilide and its derivatives, e.g. those in which one or both benzene nucleus (s) carry (s) one or more lower alkyl or lower alkoxy group (s). Of the compounds discussed above, benzoic acid, substituted benzoic acid, 4- (a, a-dimethyl) benzyl phenol and p-toluenesulfonanilide have proven to be outstandingly suitable. In order to meet the above-mentioned parameters regarding viscosity and Tg values, which are preferred for a toner powder for use in a contact melting system, the modified epoxy resin must have a low molecular weight fraction with a molecular weight of less than 4000 and an optionally crosslinked high molecular weight fraction with a molecular weight of over 4000, preferably over 10,000. A modified epoxy resin with a low molecular weight and a high molecular weight fraction can e.g. by blocking the epoxy groups of a technical epoxy resin or a mixture of such epoxy resins to at least 5% and preferably at least 10-35% (depending on the epoxy resin used as the starting material) by chemical reaction with a monofunctional carboxylic acid or a monofunctional phenol or N-aryl arylsulfonamide while the remaining epoxy groups 5 645197 up to a total of at least 50% by internal methods to carry out the blocking reaction molecular reaction with the alcoholic hydroxyl groups of the epoxy groups of the starting resin for the formation pen of the resin itself can be obtained. The first of the desired modified epoxy resin in the course of Blocking method delivers the low molecular weight, making the toner powder itself are most suitable the latter blocking method of the higher molecular weight 5 compared to the separate production of the modifi- laren share. Both of these types of blocking can grace the resin a number of advantages. be carried out simultaneously or successively. The toner powder according to the invention is preferably used In the second case, a higher viscosity and a larger one is obtained by mixing the epoxy resin or the mixture Melting range than with simultaneous measurement of epoxy resins, starting from these in a melted methods, but the Tg remains practically the same. i0 nen shape, at temperatures between approximately 150 and However, the desired higher molecular weight fraction can be 250 ° C. with the coloring material and, if desired, further by reacting a part of the epoxy groups of the component, such as a polarity control agent, soft starting resin or the starting resin with a bifunctionalizing agent, which improve the flowability, and tional or polyfunctional epoxy hardeners are obtained, and the blocking reaction is carried out, whereby linear or cross-linked structures are obtainable 15 or reactions according to the above information during the process. In this case, too, the reaction methods can be mixed. Can be used simultaneously or in succession during this mixing process. The blocking reactions are easy and without difficult epoxy hardeners, in particular 4,4'-isopropylidene diphe- phene to a desired final stage. If proven at noi. Blocking reaction used an N-aryl-arylsulfonamide A third possibility for obtaining the higher molecular weight, the epoxy groups of the starting resin preferential part consists in blocking this in a separate reference by the amide, whereby only a moderate bloc process or to chew it as a technical product - Labeling by intermolecular reaction with the alcoholic oils. Then it can be provided with the low molecular weight fraction hydroxyl groups of the resin itself. When mixed into, which is a monofunctional carbon by one of the above-mentioned blocking reaction. If 4,4'-isopropylidenediphenol is used for the production of the higher molecular weight acid or a monofunctional phenol, it may be expedient to use a catalyst, the resulting product is generally referred to as phenoxy resin. in order to prevent predominance of the intermolecular reaction. Such resins have a practically linear molecular structure, since otherwise unusable toner powders with much too high and a molecular weight between 10,000 and 80,000 could result in melting points. Suitable catalysts An example of a commercially available phenoxy resin is “Rüta- 30 for this purpose include quaternary ammonium pox” type 07-17 (molecular weight 30,000), a product of the compounds; is particularly useful as a catalyst e.g. Bakelite company. Tetramethylammonium chloride. The increase in the molecular weight of the starting ep- The color materials required for the production of oxy resin other than black colored by an epoxy hardener is generally considerable. is larger and is obtained faster than with intermolecular 35 oils used for the production of the toner powder Reaction. When using an epoxy hardener to form resins not sufficiently soluble; good solubility is, however, the higher molecular weight fraction is preferred especially for the production of transparent toner powder. 40-75% of the total number of the starting epoxy groups of the movern is desirable, as is largely required for many multi-color copying methods of differentiated epoxy resin or epoxy resins. As an additional benefit, the invented by chemical reaction with a monofunctional toner powder according to the invention that cationic carboxylic acid, a monofunctional phenol, contains numerous dyes in the resins or N-aryl-arylsulfonamide and only a small part can be dissolved sufficiently by zen. intermolecular reaction and at most 25-60% by re- To produce a developer of two-component action blocked with an epoxy hardener. The toner powder according to the invention can either be of the type The toner powder according to the invention can be obtained immediately after its production or at a later date by methods known per se, such as the point in time at which the desired carrier particles are mixed. e.g. Kneading, extrusion or hot melt processes. With the. If the developer for magnetic brush development first mentioned method, the resin, color material is correct, are preferably iron particles, which are combined with one and, if desired, other components, e.g. Polari surface coating can be provided as a carrier control means, used with each other at temperatures between so. The desired particle sizes of the carriers are mixed at about 90-160 ° C. With the hot-melt method, he is known in this technique. Generally they are between 50 mixing generally follows at temperatures around 200 ° C. and 150 µm, depending on the particle sizes of the After the mass obtained has cooled, it is formed into particles of two components. grind to the desired size, the sizes generally 1 to 8% by weight of toner particles. mine are between 2 and 50 | xm. The desired portions of the toner powders of the invention can generally be sized by spraying the hot mixture with conventional carriers, e.g. Iron powder and melt can be obtained in a cooler medium. layered iron oxide powder, sufficient negative La- From the three manufacturing processes mentioned above, man has. If desired, one of the hot melt and kneading methods added to this position as the conventional charge control agent known per se can be particularly preferred in order to obtain a higher negative charge. A proven. The toner powders produced in this way were very particularly suitable, negative-working charge control agents, and gave satisfactorily reproducible values. “Atlac” type 282E, a technical product from the At-resp. Properties, especially regarding their especially read company. The active component of this agent is important properties such as charging behavior, stability 4,4'-isopropylidene-diphenol-propylene oxide fumarate and meltability. This may include the fact that the acid number is 10-20. are attributed to the fact that in these processes the temperatures and if positively chargeable toner powders are required and reaction times are easiest to control, the toner powders according to the invention can be combined with one of them. Furthermore, it was found that these positive charge control agents are mixed, as described in 645 197 the applicant's post-published GB-PS 1550 555 or the applicant's post-published Dutch patent application No. 7711623. Both of these types of positively charged powders based on modified epoxy resins are not intended to fall under the present patent and are not claimed here. However, two component developers can be made in which the toner powders according to the present invention assume a charge of positive polarity without incorporating a polarity control agent into the toner powder itself. This can be achieved by using an appropriate carrier. Such carriers can be obtained by various methods, such as are described in GB-PS 1 251 752.1 389 744.1 438 973, 1 342 748 and 1 373 000. If the toner powder according to the invention as such, i.e. as a one-component developer to be used, a magnetizable material is preferably incorporated into the resin as a colorant; this enables the use of the toner powder in the so-called magnetic brush development systems, which have proven to be particularly suitable for the use of one-component developers. Generally 10-50% by weight of magnetizable material is required for this purpose.