DE2165328A1 - MANUFACTURE OF ELECTROSTATIC TONER MATERIAL - Google Patents

Description

28, Üez.

AGI A-GEYAEEI AG

LEVEEKUSEN ·. ,.

Manufacture of electrostatic toner material.

Priority: Great Britain, JO December 1970, 8 June 1971 (compl.)

Note no. 61 855/70

The subject of this invention is the manufacture of an electrostatic Toner material and the resulting electrostatic toner material itself.

According to an already known method, electrostatic ■ latent images with the help of a toner made up of tiny particles a certain material - usually a resin - which is usually colored and special triboelectric Has properties converted into visible images. Depending on With the sign of the electrostatic charge, the resin particles are either attracted to the charged zones of the "latent" image and deposited there or repelled from the charged zones and deposited at the discharged points. This process is called as the development of the electrostatic latent image. That latent image itself can be generated by methods already known e.g. by exposing a uniformly electrostatically charged, photoconductive surface that contains zinc oxide, selenium or a suitable organic compound as a photoconductor.

In order to better control the development of the latent image, the toner is used together with solid carrier parts brought or you can also put the toner particles in an insulating Disperse liquid.

If a dry developer is used, it consists of two ■ ■ Components, namely a finely ground ,, pigmented or

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colored resin toner and a relatively coarse-grained carrier material with a particle diameter between about 0.3 and 1.5 mm. The development mixture is left to develop the latent image just trickle over the exposed plate. The carrier material - e.g. glass or steel balls, which can be coated with a resin-like, f. forming product, carries the toner trickling over the plate and by the formation of static electricity at the same time charges the toner particles with the correct sign. A toner-laden carrier particle slides over an electrical one If there is an interruption on the surface of the plate, the toner particles will only settle on the charged areas of the image but not on the discharged parts or background

k divide the picture. There should be toner particles on the background parts of the image, they are carried away by the following carrier particles running over the plate. This operation results in an image composed of toner particles that are electrostatically attracted to the image surface. This powder picture can be fixed on the photoconductive plate or transferred to a receiving surface - e.g. a sheet of paper. The transfer can be done by taking the powder image optionally in the presence of an electrostatic field with the receiving surface brings into contact. If then the The receiving surface - e.g. the sheet of paper - is peeled off the image-bearing surface, it takes up a considerable amount Toner particles in the shape of the desired image with. This image can then subsequently be converted into a permanent image - i.e. be fixed - by any convenient method, such as heating or fixing by solvents.

The photographic and physical properties of the Toners should of course be as cheap as possible. So the choice of the binder contained in the toner material is made mainly determined by its triboelectric properties, since the binder must enable the toner to receive a charge with a sign that is equal to the sign of - Photoconductor and carrier are opposite. In case of a

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The most suitable binders for the toner are polystyrene and polymers of styrene homologues, copolymers of styrene and acrylates or methacrylates, rosin and polyalcohol esters of rosin. Also through the physical properties the choice of binding agent is determined. It must have a melting point which is such that the properties of the toner are not affected by normal processing temperatures to be changed. On the other hand, the toner must by itself

Heat can be fixed while the paper on which the toner image has been transferred, are not countersunk by this heat darf.- The melting range of the toner therefore should preferably be between 80 and 140 ⁰ C. The binders listed above can be adapted to their intended use, in particular by adjusting their molecular weight. If the melting point is too high, it can be reduced by adding plasticizers - ζ. · Β. Ester compounds such as dibutyl phthalate, triphenyl phosphate or by adding low molecular weight polyethylene or polymeric plasticizers such as polyvinyl acetals can be reduced. The toner should also only have a low degree of brittleness, because a toner that is too brittle would contaminate the selenium drum, so that, as a result of the development of dust, fog forms on the image and the apparatus becomes soiled.

The toner must also have appropriate plasticity properties. The toner particles collide in the development zone constantly together, and these collisions must not be part of it cause the triboelectric and physical properties of the toner to change. You can only do that by using it of a sufficiently elastic toner, i.e. a toner that exhibits a certain degree of deformation when subjected to pressure learns, but his again immediately after the end of the print takes on its original shape. Connections that work for one Suitable toners with very good elastic properties are e.g. polyvinyl butyraldehyde acetal, polyethylene and copolymers like those made from vinyl acetate and ethylene.

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303831/1038. BATH ORIGINAL

It is now the object of this invention to provide an electrostatic toner material with excellent triboelectric and to create physical properties.

According to the invention, an electrostatic toner material is created, the finely divided particle with a diameter between 1 and JO microns of a mixture of coloring substance and one Mixture of the resins (A), (B) described below and (C) in which the weight ratio of coloring matter to resin mixture is not less than -5:95 "uncL is greater than 15 = 85, and the resin mixture is the following resins (A), (B) and (C) in weight ratios of 40-60, 20-40 or 5-20 based on the total weight of (A), (B) and (C) contains:.

Resin (A), which is a polymer or copolymer that is

repeating units of at least one styrene

contains the following formula:

in which R represents hydrogen or methyl,

Resin (B), which is a homopolymer of butyl acrylate or methacrylate or is a copolymer of butyl acrylate or methacrylate and methyl acrylate or methacrylate, ^ 'the up to 80 wt .-% methyl acrylate or methacrylate

contains, and

Resin (C), which is a polymeric, thermoplastic plasticizer, such as polyvinyl butyral, polyethylene or copolymer is made of vinyl acetate and ethylene.

The invention also includes an electrophotographic process, which is characterized in that an electrostatic image is made visible by adding an electrostatic Brings image-bearing image surface with a toner material in contact, the finely divided particles with a diameter between

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1 "and 30 microns of a mixture of coloring substance and a mixture of the resins (A) described below,

(B) and (C) in which the weight ratio of coloring agent Substance to the resin mixture not smaller than 5:95 "and not is greater than 15:85, and the resin mixture is as follows Resins' (A), (B) and (C) in weight ratios "of 40-60," 20-40 or 5-20 based on the total weight of (A), (B) and

(C) contains: -

Resin (A), which is a polymer or. Is a mixed polymer that Contains repeating units of at least one styrene with the following formula:

R-C = CH

in which R represents hydrogen or methyl,

Resin (B), which is a homopolymer of butyl acrylate or methacrylate or is a copolymer of butyl acrylate or methacrylate and methyl acrylate or methacrylate, the up to 80 wt .-% methyl acrylate or methacrylate contains, and.

Resin (C), which is a polymeric, thermoplastic plasticizer, such as Polyvinyl butyral, polyethylene or mixed polymer Vinyl acetate and ethylene is.

The coloring substance (pigment or dye) is said to be in the toner be present in an amount that makes the toner intensely colored, so that a clearly visible image is obtained. The pigment is usually a black pigment such as carbon black. Should a color copy organic pigment or a dye can be used. Usually this is the weight ratio from coloring substance to resin mixture not less than 5 = 95 and not greater than 15:85 · The mixing of the resin mixture with the coloring substance is preferably carried out in a ball mill.

The coloring substance is mixed with one of the resins (A), (B) and (C)

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containing resin mixture intimately mixed. The resin (A), which is present in this mixture in a weight ratio of 40-60 based on the total weight of the resins (A), ■ (B) and (C), is a polymer or copolymer; of repeating units of at least one styrene with the formula:

in which R represents hydrogen or methyl.

In a preferred embodiment of the invention, the resin (A) is a copolymer of 50 "to 63% by weight of repeating Units of at least one styrene compound according to the above formula, such as styrene, together with a minor one Amount <X-methylstyrene and from 50 to 37 wt .-% repeating Units of at least one alkyl methacrylate whose Alkyl groups consist of 1 to 4 carbon atoms. It can be methyl, ethyl, n-propyl, isopropyl-5η-butyl and isobutyl methacrylate and mixtures of these compounds can be used. When interpolymerizing e.g. styrene, <X-methylstyrene and one Alkyl methacrylate contains the resulting copolymer usually a small amount too - usually less than about -1 % By weight - units containing free carboxyl groups which likely to be formed in a saponification reaction occurring during polymerization.

The mixed polymer of alkyl methacrylate and styrene is mixed in a weight ratio of 20 to 40, based on the total weight of resins (A), (B) and (C), with a homopolymer of butyl acrylate or methacrylate or a mixed polymer of butyl acrylate or methacrylate and methyl acrylate or methacrylate mixed with up to 80% by weight of methyl acrylate or methacrylate. Preference is given to the homopolymers of n-butyl methacrylate and the copolymers of n-butyl methacrylate and methyl acrylate (25:75% by weight ).

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The third component is a polymeric, thermoplastic Plasticizer in a weight ratio of 5 "to 20 to the resin mixture added. The plasticizer is polyvinyl butyral, polyethylene or a copolymer of ethylene such as a copolymer made of vinyl acetate and ethylene. If polyvinyl butyral is used, the polymer chain can contain smaller amounts of units made of vinyl alcohol and vinyl acetate.

The different resins can be mixed together by melting and the coloring substance is added to the melt with stirring until a homogeneous mixture is formed Has. The solid mass after cooling is crushed and ground to a particle size by grinding in a ball mill brought between 1 and 3Q microns. The resulting powder does not stick at ordinary temperature, so it is easy over the top soaking the latent electrostatic images surfaces can flow.

The toner is used to develop the electrostatic images loosely poured onto the latent electrostatic image, where it is electrostatically attracted in the zones of the latent image will. The most widely used development method is Cascade development in which the electrostatic toner is mixed with a granular carrier that is either electrical can be conductive or insulating. The granular carrier material consists of glass or steel balls that are uncoated or can be provided with a suitable coating that gives the granular carrier material the necessary triboelectric Gives properties. Normally, 1 part by weight of toner powder with about 130 parts by weight of granular carrier material mixed.

If the carrier particles are brought into close contact with the particles of the toner powder, they are given a charge. whose sign is opposite to that of the toner particles, so that the latter envelop the carrier particles. Intended to If a positive reproduction of an electrostatic image is to be produced, the support is chosen such that

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the toner particles receive a charge whose sign corresponds to opposite to the electrostatic charge. In order to obtain a negative copy, the carrier can be chosen in such a way that that the toner particles acquire a charge which has the same sign as that of the electrostatic image.

The carrier particles must be sufficiently large; in any case larger than. the toner particles, the shape of which must be such that they roll over the image-bearing surface. Preferably, glass beads between 600 and 800 microns in diameter are used. The toner particles are attracted by the 'charged areas of the surface and separated from the carrier, the roll further due to the gravity W. . . ■. '

Carrier particles and their treatment are described in British patents 679 715, 686 466, 1 172 839, 1 174 571, 1 174 572, 1 I74 573, 1 225 980, 1 227 Λ71, 1 232 117 -and 1 232 118 described.

If the carrier particles used together with the electrostatic toner material according to the invention are glass beads, they can be subjected to a special pretreatment in which the degreased glass beads are treated with a trialkoxysilane or an organic phosphorus compound and coated with a layer of ethyl cellulose. ψ Such a pretreatment of carrier glass beads is the British patent application 61 885/70. and in the application filed by the applicant on the same day as this application for "Process for the production of electrostatic carrier material".

Fixing the toner particles on paper or another Carrier is done by heat or fixation by solvents. Applies thermal energy to the toner or becomes a solvent added, so the toner becomes soft, becomes more liquid, flows together and irreversibly combines with the Paper carrier .. ■

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The invention will now be illustrated by means of the following examples will.

Example 1

A toner mixture is produced from 5 »2 parts by weight of polystyrene with a molecular weight of about 30,000 and -1 part by weight of polyvinyl butyral with a molecular weight of about 30,000, which in addition to the polyvinyl butyral groups also contains about 20% by weight of vinyl alcohol groups and contains 2.5% by weight vinyl acetal groups. Then be 2.8 parts by weight copolymer of methyl methacrylate and n-butyl methacrylate (50:50 mole -%, corresponding to 39: 61 wt .-%, which - as measured in chloroform "at 20 ⁰ C - 0.2 has a limiting viscosity number) is added and 1 part by weight Spezialschwarz IV (registered trademark for Buss sold by the Deutsche Gold- und Silberscheideanstalt, Frankfurt / Main). ■

The ingredients are dry blended together at a temperature of I50 - 160 ⁰ C and melted, the melt durchgeknedet 30 minutes at the same temperature. After cooling and comminuting to a particle size of about 1 mm, this powder is ground in an aqueous medium in a vibrating ball mill for 15 hours. After drying and sieving, a toner with a particle size of 37-5 microns is obtained, which has a fixing temperature of. about 130 ⁰ C has.

Then, by mixing 1 g of this toner powder with 100 g of carrier particles in the form of glass beads with a diameter a developer mix of 600-800 microns.

After positive charging of a selenium drum and imagewise exposure according to an original, the developer mixture is left trickle over the electrostatic latent image, 'whereupon a black toner image remains on the selenium drum. This image is then transferred to a paper support and the image is fixed on this paper support by heating.

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A sufficiently dense image is obtained, though sharp, but quite smoke. After further developments with the same developer mix, only a minor one becomes Change in contrast noted.

If you were to use the above method, the mixture would be Polystyrene, polyvinyl butyral and mixed polymer of methyl methacrylate and n-butyl methacrylate in the toner through pure Replacing polystyrene would produce images of good density; which also feel quite rough, however are fuzzy and where "due to further developments with the same developer mixture, the fogging is considerable increases, while the image density - i.e. the contrast, decreases significantly. - -

Also used for the developer mix made of polystyrene and Euss nor added polyvinyl butyral as described above, there would be a slight improvement with repeated use with regard to the obfuscation, the however, other disadvantages would still be present.

If you replace the polyvinyl butyral with polyisobutyl methacrylate, you get a better density and the copy still feels rough; however, the obfuscation still increases with repeated developments. . "" ---- ■■

This clearly shows that only with the inventive Mixture, the styrene polymers, polyvinyl butyral and 'mixed polymer of methyl methacrylate and n-butyl methacrylate contains, sharp, high-contrast images with good density can be obtained and that even with repeated use this developer mixture neither fog nor contrast decreases. '

Example 2 ■ -

A toner mixture is prepared from 5.2 parts by weight of resin Ά, 2.8 parts by weight of resin B, 1 part by weight of resin C and Λ part by weight of carbon black "Spezialschwarz IV".

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Resin A is a copolymer comprising 50 'wt .-% styrene, 5 wt .-% <\ methyl styrene and 45 wt .-% isobutyl contains.

Resin B is a copolymer of methyl methacrylate and n-butyl methacrylate (39:61% by weight).

Resin C is polyvinyl butyral that contains about 20 weight percent vinyl alcohol groups and contains 2.5 wt% vinyl acetate groups.

This toner mixture is melted as in Example 1 and ground in a ball mill. It has a fixing temperature of about 110 ^° C.

1 g of this. Toner powder comes with 100 g of carrier particles in the form of glass beads with a diameter of 600-800 microns mixed.

Image-wise exposure, development of the latent image, transfer onto a paper support and fixing done like in example 1.

Positive images with high density and sharpness are obtained. the The fixing temperature of the powder images is very favorable Temperature range, and if there are several developments with the same developer mixture, only a very small one will work Obscuration noticeable. ·

For comparison, it is left in the above-mentioned developer mixture from the resins A, B. and C the last two substances mentioned omitted, so that only a copolymer made of styrene, oi-methylstyrene and isobutyl methacrylate is used, so it is found that there is also a lowering of the fixing temperature and that the image has a smooth surface However, when the toner powder is used repeatedly, a very high degree of fogging can be observed.

If a developer mixture is used that contains resin C in addition to resin A, the fixing temperature is somewhat lower higher, with a haze value better than Resin A alone

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is. A better contrast is obtained than in the case from polystyrene alone, however, it is inferior to a mixture of all three resins.

Example 3

In the toner mixture of Example 2, the 2.8 parts by weight of polyvinyl butyral are replaced by an equal amount. Mixed polymer of vinyl acetate and ethylene (28/72 wt.%) Replaced. The resulting toner mixture is melted as in Example 1 and ground in a ball mill. It has a fixing temperature of 108 ⁰ G.

After imagewise exposure, developing the latent image, transferring it to a paper carrier and fixing as in the example 1 positive images of high density and sharpness are obtained, even with repeated developments with the same developer mixture there is only a very slight veil to be seen.

Example 4

The procedure of Example 2 is repeated with the difference that that instead of glass spheres, steel spheres with a diameter of 300-400 microns are used as the carrier material coated with a layer of cellulose nitrate. The coating with cellulose nitrate takes place in a ball mill in which the steel balls Tnit-4 wt .-% cellulose nitrate, in Methyl isobutyl ketone dissolved, mixed. The ball mill is heated with an ultrared lamp so that the solvent. slowly evaporated and the ball mill by an axial out. steppipe leaves.

0.5 g of the toner mixture from Example 2 is added to 100 g the steel balls pretreated as described above and the developer mixture used as in Example 1 to to develop a negatively charged and imagewise exposed zinc oxide layer. The sign of the charge of the toner is now positive, and you get a sharp positive image of the original.

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Example 5

The "procedure of Example 2 is repeated with the difference that that the resin B by a copolymer of methyl methacrylate and n-butyl methacrylate (33/67 wt.%) replaced,, is.

Very dense and sharp positive images are also obtained. "".

Example 6

A toner mix of 5 _? 2 parts by weight of resin A, 2.8 parts by weight of distorting resin B, 1 part by weight of resin 'C and 1 part by weight of Calco Oil Black. '

Resin A is a copolymer of 56% by weight styrene, 7% by weight α- methyl styrene and 37% by weight isobutylinethacrylate.

Resin B is a copolymer of methyl methacrylate and n-butyl methacrylate (75:25% by weight).

Resin C is polyvinyl butyral that contains about 20 weight percent vinyl alcohol units and contains 2.5% by weight of vinyl acetate units. "'

"Calco Oil Black" is the trade name for carbon black powder, sold by Pylam Products Co., USA.

The ingredients are mixed dry and then the mixture is kneaded for 30 minutes at about 135 ° C. After cooling and comminuting, 60 g of the mixture are ground in the vibrating ball mill for 15 hours with the addition of 240 ml of water. The mass is sucked off and dried in the air to a moisture content of a maximum of 0.5 % . After sieving the powder you get a toner with a. Particle size between 1 and 30 microns and a melting temperature of about 117 ° C. ", ■"

1 g of this toner powder -will with 99 S glass beads with a Mixed in diameter between 600 and 800 microns. These

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Developer mixture is used according to the cascade method a positive image on a negatively charged zinc oxide paper to produce that had been exposed imagewise. The image on the paper is made by applying heat or a solvent fixed. It is an image of sufficiently high density that only a low density in the areas not belonging to the image or has no obfuscation at all.

. Example 7 '■

A layer consisting of an organic photoconductor, as described in Belgian patent 7 ^ 7 849, is negatively charged and then exposed imagewise. To develop the latent image thus created, the developer mixture consisting of toner and glass beads according to Example 6 ™ is allowed to trickle over the exposed plate. The powder image is electrostatically transferred to a piece of paper, on which it is fixed, for example by means of heat. -The powder remaining on the organic photoconductor is removed electrostatically and mechanically; then the plate with the organic photoconductor is immediately ready again for image-wise development.

The resulting image showed good line reproduction and a satisfactory area coverage of the dark zones with only little background deposition. .

Example 8

Very good positive images are obtained on zinc oxide paper or on paper containing organic photoconductors - as described in Belgian patent 7 ^ 7 849 - if a toner mixture prepared according to Example 6 is used which contains the same components as however, instead of Calco Oil Black, the only difference is that it contains the same amount of Waxoline Nigrosine NS (trade name for an Euss from Imperial Chemical Industries, England).

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Example 9

A method according to the first part of Example 2 is used the difference repeats that the copolymer consists of Methyl methacrylate and n-butyl methacrylate (39:61% by weight) the same amount of poly-n-butyl methacrylate is replaced. the Fixing temperature of the toner "is about 125 ° C. With the toner material Copies made have the following properties:

- high density

- sharp positive images _

- an acceptable fixing temperature.

The toner "has high mechanical strength; this will "demonstrated in a continuous process," in which always same developer mix "is used.

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Claims (1)

2185328 Claims (1y electrostatic toner material, characterized in that that there are finely divided particles with a diameter between 1 and 30 microns of a mixture of coloring agents Substance and a mixture of those designated below Resins (A), (B) and (C) in which the weight ratio of coloring substance to resin mixture is not is less than 5:95 'and not greater than 15:85 and that Resin mixture the following resins (A), (B) and (C) in weight ratios from 4-0-60., 20-40 or »5-20 based on the total weight of (A), (B) and (C) - contains: .... Resin (A), which is a polymer or copolymer, the repeating units of at least contains a styrene with the following formula: in which E is hydrogen or methyl, resin (B), which is a homopolymer of butyl acrylate or ■ methacrylate or a copolymer of butyl acrylate or methacrylate and methyl acryl at odor methacrylate is up to 80 wt .-% Molhyi-. acryl at. or methacrylate, and resin (C), which contains a polymeric plasticizer such as polyvinyl butyral, Polyethylene and copolymer made from vinyl acetate and is ethylene. 2. Electrostatic toner material according to claim 1, characterized in that the resin (A) is polystyrene. 3 ". Electrostatic toner material according to claim 1, characterized in that characterized in that the resin (A) from 50 to 63% by weight consists of repeating units of at least one styrene with the following formula: GV.526. . - 309831/1038 BADORtGINAL R-C = CH in 'the R represents hydrogen or methyl. ,, and 50 to 37% by weight of at least one alkyl methacrylate, the alkyl group of which contains 1 to 4 carbon atoms. 4. Electrostatic toner material according to claim 3, characterized in that the resin (A) consists of a copolymer Is styrene and isobutyl methacrylate; . 5- Electrostatic toner material according to claim 3, characterized characterized in that the resin (A) is a copolymer of styrene, rt-methylstyrene and isobutyl methacrylate. 6. Electrostatic toner material according to claims 1 to 5, characterized in that .. that the resin (B) is a homopolymer of n-butyl methacrylate. 7 · Electrostatic toner material according to claims 1 to 5, characterized in that the resin (B) is a mixed poly is a merisate of n-butyl methacrylate and methyl methacrylate, which contains 75% by weight methyl methacrylate. 8. Electrostatic toner material according to claims 1 to 5, characterized in that the resin (B) is a mixed poly is merisate of n-butyl methacrylate and methyl methacrylate, which contains 39 wt .-% methyl methacrylate. 9 · Electrostatic toner material according to claims 1 to characterized in that the resin (B) is a copolymer of n-butyl methacrylate and methyl methacrylate, which contains 33% by weight methyl methacrylate. "10. Electrophotographic process in which an electrostatic Image is made visible by having a 309831/1038 brings electrostatic image-bearing image surface into contact with electrostatic toner material, characterized in that the electrostatic toner material finely divided particles with a diameter between 1 and 30 microns of a mixture of coloring substance and a mixture of the resins (A), (B ) and- (C), in which the weight ratio of coloring substance to resin mixture is not less than 5 = 95 and. is not larger than 15:85, and the resin mixture consists of the following resins (A), (B) and (C) in weight ratios of 40-60, "20-4-0 and 5-20, respectively, based on the total weight of (A ), (B) and (C) contains:
Resin (A), which is a polymer or copolymer that repeating units of at least one. _ Contains styrene with the following formula: E.
EC = CH -in the E represents hydrogen or methyl, resin (B), which is a homopolymer of butyl acrylate or methacrylate or a copolymer of butyl acrylate or methacrylate and methyl acrylate or methacrylate, which is up to 80% by weight of methyl acrylate or methacrylate, and Resin (C), which is a polymeric plasticizer such as polyvinyl butyral, Polyethylene and copolymer of vinyl acetate and ethylene is. 11. The electrophotographic process according to claim 10, characterized in that the resin (A) is a copolymer, the -fo from 50 to 60 weight of repeating units consisting of at least one styrene of the formula.: GV.526 ^y 3 0 9 8 31/10 3 8 E.
I.
EC = CH In which E is hydrogen or methyl, and 50 "to 40% by weight of repeating units of at least an alkyl methacrylate whose alkyl group is 1 "to 4 carbon atoms "includes. 12. Electrophotographic process according to claim 11, characterized in that the resin (A) is a copolymer is made of styrene and isobutyl methacrylate. 13. Electrophotographic process according to claim 11, characterized characterized in that the resin (A) is a copolymer Styrene,-methylstyrene and isobutyl methacrylate it.t. 14. Electrophotographic process according to the claims 8 "to 13, characterized in that the resin (B) is a Is homopolymer of n-butyl methacrylate. 15 · Electrophotographic process according to claims "to 13, characterized in that the resin (B) is a copolymer from 25% by weight n-butyl methacrylate and 75% by weight Is methyl methacrylate. 1G. El oktrophotographicches method according to claims 8 "bir, 13, characterized in that the resin (B) is a copolymer from 61% by weight n-butyl methacrylate and 39% by weight Methyl methacrylate. is. 17 · Electrophotographic process according to the claims 8 "to 1.3, characterized in that the resin (B) is a copolymer of 67% by weight n-butyl methacrylate and 33% by weight Is methyl methacrylate. 18. Improved electrostatic developer made from spherical Carrier particles with a diameter of 0.3 "to 1.0 η and toner material, characterized in that 309831/1038 BADORiQIWAL 21SS32B- that the toner material according to claims 1 - <? Lf electrostatic attraction is releasably applied. 19- Electrophotographically generated images, characterized in that that they were generated with the aid of the electrostatic developer according to claim 18. 309831/1038
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