Developer composition and process for using same

PATENT DESCRIPTION

Additional patent to patent No.

Reported: 10.10.72 (P. 158 183)

Priority: 12.10.71 United

United States of America

The application was announced: 01.06.73

Patent description published: 01.03.1977

MKP G03g 9/02

Int. Cl.² G03G 9/10

Inventor of the invention: _

Patent Holder: Xerox 'Corporation, Rochester, (United States of America)

Electrostatographic developer and

The present invention relates to an electrostatographic developer consisting of a developing powder which is a colored resin. The developer of the invention contains additions that allow the production of very good quality copies in industrial duplication duplicating machines.

Many electroscopic developing powders are known. The most commonly used developing powders are resins colored with appropriate pigments and although they have appropriate tribodlectric properties they also have disadvantages, among others tendency to settle on the surface of the photoreceptor and remain on this surface after moving the image.

This results in the need to remove the residual image to avoid the formation of spectral images in subsequent copies and to prevent the formation of a thin powder layer on the photoreceptor surface. Incomplete transfer of powder particles is undesirable because it reduces the optical density of the image of recent copies and causes the need to clean the photoreceptor surface from powder residue, which can cause scratches or other damage to the photoreceptors.

The different cleaning systems used, unfortunately, do not completely remove all types of developing powder particles from all types of photoreceptors adapted for multiple use.

However, this is not a disadvantage of purification systems, but is a disadvantage of specific powders used in conjunction with specific photoreceptors. If the specified powder did not show a significant amount of waste that adheres to the specific photoreceptor, the purification systems described above would effectively remove all the powder remaining on the photoredzptoazz.

ίο Significant improvement in the properties of developing powders was achieved by incorporating into the developer composition a small amount of hydrophobic fatty acid metal salt, which gives British Patent Specification No. 1,172,839. The developing powder of colored resin proposed in this patent contains the addition of 0.02 - - 20% by weight of fatty acid metal salt. This additive causes a significant reduction in friction between the powder particles and between the powder and carrier particles. Due to this addition, the resulting developing powder exhibited the ability to flow freely, less tendency to deposit of particulate, due to friction, particles on the surface of the photoreceptor, which allowed for obtaining more good quality copies. However, it turned out that even better developing powders can be obtained, the use of which is effectively eliminated. forming a thin film of developing powder. on the photoreceptor. They provide greater

S9 055

055 the optical density of copies at image locations, reduces the optical density of the background copy and also exhibits better more stable triboeectric properties and allows the formation of a thin film of developing powder on the photoreceptor that is used repeatedly with sufficiently long-term adjustment.

The electrostatographic developing material according to the invention consists of particles of finely divided developing powder, and as additions of a smaller amount, by weight to this powder, of finely divided solid friction reducing material, with a hardness lower than the hardness of the developing powder, and showing greater ability to reduce friction. than developing powder; the friction reducing material being characterized by a greater than powder causing the ability to form a thin, adherent layer on the surface when applied from the mixture by lateral forces, a smaller and smaller amount in weight ratio to the developing powder, of a finely divided abrasive with a hardness greater than the reducing material friction and developing powder.

The electrostatographic developer according to the invention consists of a developing powder consisting of a colored resin in which the amount of dye is 1 '- 30% by weight based on the developing powder, and optionally a carrier in an amount of 10 - 1000 parts per one part of developing powder.

In addition, the electrostatographic developer of the invention contains a two-component additive consisting of a solid friction reducing substance in the amount of about 0.01-10% by weight and fine abrasive in sub-micrometer dimensions of about 0.01-10% by weight based on the amount of developing powder . The friction reducing substance is saturated or unsaturated, optionally substituted fatty acids with 8 - 35 carbon atoms or salts of the above fatty acids, fatty alcohols corresponding to the above acids, esters of mono- or polyhydric alcohols with the above acids and the corresponding amides, polyethylene glycols and polymethoxyethylene glycols, terephthalic acid, isophthalic acid, 2,5-dimethyl terephthalic acid, 2,5-dichloroterephthalic acid, p-phenylenediacrylic acid, aniseic acid, terephthalaldehyde, terephthalic acid salts, cholesterol, peoChoorpentacycycodecane, polycaporlactams with a molecular weight not greater than 4000, fluorocarbon compounds with a low molecular weight e.g. short-chain telomere tetrafluoroethylene and low molecular weight prismatalphthyl ether, while the abrasive material Is colloidal silica, surface-modified organophilic silica, optionally surface treated aluminum silicate, calcium silicate, calcium carbonate, titanium dioxide, aluminum oxide, antimony trioxide barium, calcium or strontium, magnesium oxide, zirconia or mixtures thereof.

As developer powder, the present invention may contain any electroscopic developer powder, preferably colored or dyed. Typical developing materials are polystyrene resins, acrylic resin, polyethylene resin, polyvinyl chloride resin, prliakoylamide resin, terephthalate resin. polyethylene, polyamide resin and copolymers, mixtures and multi-component mixtures. Suitable developing powders are preferably suitable vinyl resins with a melting point of at least 43 ° C. Suitable vinyl resins are homopolymers or copolymers of two or more vinyl monomers.

As monomers for the production of vinyl polymers, styrene vinylnaphthalene, monoolefins such as ethylene, propylene, butyl, and the like, vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate and the like, alpha-methylene aliphatic monocarboxylic acid esters such as methyl acrylate are used , ethyl acrylate, t-butyl acrylate, isobutyl acrylate, dodecyl acrylate, n-octyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate and the like, vinyl ethers such as vinyl methyl ether, vinyl isobutyl ether, vinyl ether and the like, vinyl ketones such as methyl vinyl ketone, vinyl hexyl ketone, melyl isopropylene ketone and the like, and mixtures thereof. The appropriate developing powder material used in the process of the invention typically has an average molecular weight of from about 3,000 to about 500,000.

Any suitable dye or pigment can be used to stain the developing powder particles. Developing powder coloring agents are well known and are, for example, carbon black, nitrosine, aniline blue, Oalco Gil blue, chrome yellow, duPomt fat red, Ciinoline Yellow, methylene chloride, phthalocyanine blue, malachite oxalate, lamp carbon black, Bengal pink and mixtures thereof. The pigment or dyes must be on the developing powder in an amount sufficient for strong coloring to form an easily visible image on the substrate. For example, when one wants to obtain ordinary photocopies of documents, the developing powder may contain black pigment such as carbon black or black dyes such as National Anilina Products Amaplast Black.

The pigment is used in an amount of about 1-38% by weight relative to the total amount of colored developing powder. If the developing powder coloring agent is a dye, it can be used in much smaller amounts. In order to use the developing powder of the invention for the developing process, the powder should have an average particle size less than 30 microns.

Metal fatty acid salts may be used as the friction reducing additive, but other substances with suitable properties may also be used. It is important that the lubricating or friction reducing additive is able to form a thin film adjacent to the surface of the photoreceptor, capable of repeated use during repeated cycles of the electrostatographic process. This add-on does not have to create a completely continuous film on the image surface, although many of these materials create such a film. Friction reducing materials tend to fill surface cavities and cover fine hills only with a monolayer of friction reducing material.

Such material must exhibit properties that enable it to be deposited on the imaging surface in a much easier manner than the deposition of used developing powder. The hardness of the taita-reducing material is associated with 'the ability of this additive to form a precipitate' or film on the image surface. So the friction reducing material has to be more. softer than the selected developing powder. Determining whether the selected friction reducing material is softer than the selected developing powder is carried out by any hardness determination method. For example, using a Shore hardness tester, A, B, C or D scales, and using methods according to ASTM D-1706; it can be determined if the material has a lower hardness than the selected developing powder and whether it is. effective. The melting point of the friction reducing additive should be. be slightly higher than the ambient temperature.

Friction reducing material. it must also have a higher friction-reducing capacity than the chosen developing powder. Any dynamic measurement method can be used to determine the relative friction-reducing ability of the tested friction-reducing materials compared to the developing powders. The test consists in comparing the degree of friction reduction caused by. a material that reduces friction in relation to the developing powder when they are placed between two mating surfaces in motion relative to each other. The mating surfaces should be sufficiently flat and each of them should have a kinetic coefficient of friction greater than the coefficient of friction of the material reducing the friction and the coefficient of friction of the developing powder.

A useful method is that a flat piece of rubber-like material stretches over the image surfaces covered with the tested materials, then the values ​​are determined. relative friction coefficients of the materials used to cover the surface.

The flat bar is rubbed in the frame, it is used in conjunction with the lock mechanism and base supporting the surface of the photoreceptor. The flat can be a piece of rubber-like polyurethane with dimensions: length 36 mm, thickness 1.5 mm and width 12 mm. The edge of the flat that touches the imaging surface is bevelled or skewed at an angle of 60 ° to the horizontal. The flat bar should be attached so that the slant place extends in the direction of movement. It should be attached at an angle of 22 ° to the image surface so that its position causes wiping, not scratching the surface.

The image surfaces are generally aluminum plates, selenium coated, 270-340 mm. Friction coefficient measurements are made using an Instron Model TN (Instron Corporation Ćenton) device connected to the flat bar sledge mechanism. The strength needed for is determined. the sledge device moves, after which this value is subtracted from the value of the force necessary to move the sledge device and move the flat bar across the image surface. The result is the kinetic force of friction needed to move the flat bar itself. The normal force moving a flat bar along the image surface is measured using a gauge. The kinetic force divided by this value results in a kinetic coefficient of friction.

The friction coefficient values ​​are determined using as many selenium plates as there are materials to characterize. Any disc showing a deviation of more than 10% on the average is discarded. A different plate and a different flat plate are used for each tested material, each plate is coated with the tested material in an identical manner. Material · is always applied to the plate. in the same amount.

The friction reducing materials must also have a sufficiently high specific resistance to not damage the latent image on the image surface.

Preferred friction reducing materials with the properties set out above are metallic salts of fatty acids such as lithium, sodium, potassium, copper, rubidium, silver, magnesium, calcium, strontium, cadmium, barium, mercury, aluminum, chromium, tin, titanium, zirconium, lead, manganese, iron, cobalt and nickel as well as mixtures of these salts as well as other metal salts.

Alternatively, fatty acid ammonium salts. The fatty acids in question are e.g. .

Optionally, suitable solid fatty alcohols, esters, amides and theirs are used. derivatives of a mixture.

Preferred esters of monohydric and polyhydric alcohols and of the fatty acids discussed above are alcohol esters with 1 to 20 carbon atoms and acids which are solid in the above conditions. Preferably, alcohols such as methyl, ethyl, propyl, etc., alkylene alcohols or diols and triols having 2 to 10 carbon atoms, at least partially esterified with 8 to 35 carbon atoms. Examples of suitable esters are methyl stearate, glycerol monostearate, ethylene glycol monostearate, tri- / 12-hydroxystearate / glycerin, trisolate 1,

2, 4, -butanotriol, etc.

Preferred glycols - polyethylene and polymethoxydethylene glycols -. there are condensed products, known in _. trade under the name Carbowax. These condensation products are. solids, similar to wax, with a molecular weight of up to about 2,000.

In addition, preferred flakes are cholesterol, polycaprolactam with a molecular weight of no more than 4000, terephthalic acid, perchlorocyclodecane, and low molecular weight tetrafluoroethylene waxy fdomers. %

The friction-reducing material referred to above, when used as the sole developer additive, forms a film of grease on the Image surface with great ease, until the film formed from the developing powder is completely removed. This filim not only allows more effective removal of the developing powder - it also extends the life and increases the effectiveness of any cleaning agent used to remove developer residues.

However, when using the content of the friction reducing material, it increases steadily, resulting in a gradual steady deterioration in copy quality. By incorporating a small amount of non-lubricating material into the developer, exhibiting little abrasive properties, in a state of far-reaching fragmentation, this material causes the material to regulate the expansion of the friction-reducing material film due to its abrasive action, while the cleaning agent removes developer residue from the image surface by force, which causes the developer mixture to abrade from at least part of the imaging surface.

This combination of additives allows the friction reducing material to perform its function when the abrasive prevents the formation of an excessive, disturbing • lubricant layer. In addition, the difference in triboelectric properties between electrified agents, e.g. carrier particles and developing powder, is stabilized because the abrasive prevents harmful discharge of the developing image powder.

As a suitable abrasive, materials with a surface modified in this manner are preferably used to also give it a hydrophobic character. For example, hydrophobic silicas are obtained by reacting freshly obtained colloidal silica with at least one organosilicon compound having hydrocarbon groups and hydrolysable groups bound to a silicon atom. In one technique, the reagents and steam are pneumatically introduced in parallel streams into a reactor heated to a temperature of about 400 ° C. The organosilicon compound reacts with silane groups on the surface of the S1O2 molecules, as a result of which a bond is formed through an oxygen atom between the silicon atom in the organosilicon compound and the silicon atom in S1O2. bonded directly to the silicon atom in combination with the organosilicon group. It is best if this organic group can give the abrasive material hydrophobic properties and increase the stability of developing materials in conditions of varying humidity.

Organic groups can be saturated or unsaturated hydrocarbon groups or their derivatives. Saturated organic groups include: methyl, ethyl propyl, butyl, chloropropyl and chloromethyl groups. Suitable siliconongenic compounds are: dimethylchlorosilane, trimethylchlorosilarine, dimethylchlorosilane, methyltrichlorachilane, dimethylchlorosilane, methyltrichlorosilane, vinyltriethoxysilane. The type of organic group can affect the triboelectric properties of the developer. For example, aminopropylsilane treated silica can be used in a reversible developer.

The particle size of the abrasive should be very fine in the submicron order and be about 1,500 millimicrons, preferably about 10-100 millimicrons.

Regarding the comparative hardness of the abrasive type material, it has been found that it must be harder than both the developing powder and the friction reducing material. Most of the materials used, determined according to the Mo ^ s hardness scale, are considered very hard materials. However, a material with a hardness lower than talc on the Mohs hardness scale can also be used if it is harder than the developing powder and the friction reducing material. Materials softer than · talc are usually classified according to the technique of plunging into hardness testers. Sho.re and falls into the range of the A, B, C and D scales of this test.

The chemical composition of the abrasive additive is not important provided that it does not contain harmful impurities or does not adversely affect the process of image formation and development in the electrostaltographic system. What's more, the shape of the abrasive particles is not important, as additives with both spherical and irregular shape work effectively. The best abrasives are Areosil R 972 hydrophobic silica gel, manufactured by DeGussa Inc. and Kaophile-2 hydrophobic aluminum silicate, from the Georgie Caolin Company.

The developing material of the invention finds application in all known electrostatographic developing systems. These include systems in which the carrier is used, such as magnetic brush development and cascading, as well as systems in which the use of the carrier is not necessary, such as dust cloud development, brush development, and contact development.

The developer of the invention optionally comprises a carrier. Suitably coated or uncoated support materials for cascading are well known. The carrier particles contain any solid that causes the carrier particles to receive a charge having an opposite sign to that of the developing powder particles at the time of contact with the developing powder particles such that the powder particles wyV.

055 those preferring adhere and - surround - the carrier molecules. · If - 'you want to receive - a positive · image reproduction · of electrostatic, · the carrier particles should be selected so that the particles - of the developing powder have a charge · with a sign opposite to the sign of the electrostatic image.

Conversely, if you want to obtain a reproduction of an electrostatic image compatible with tonally (reversible), the carrier should be selected so that the particles of the developing powder obtain a charge with a sign such as the electrostatic image sign. Thus, · substances for carrier particles are selected according to their triboelectric properties with respect to the electroscopic pigment · so that when these substances are mixed or subjected to permanent contact, one developer component has a positive charge if · the second is below the first in · · tryibcoelectric series and negative charge, if the second component is in this series above the first component By appropriate selection of substances according to their triboelectric properties, the signs of their charges after mixing are such that the particles of the electroscopic pigment take on and cover the surface of the carrier particles. The particles thus selected also adhere to those parts of the electrostatic image whose surface has a greater affinity for the developing powder than the carrier particles.

Typical carriers are: steel, granular flint pellets, aluminum, potassium chloride, sodium potassium tartrate, nickel, potassium chlorate, granulated zirconium, granulated silica, · methyl methacrylate, glass and the like. · Normal and mixed media can be used. Many of the abovementioned and other typical carriers are described in U.S. Patent No. 2,615,452. Preferably, the mixed carrier particle diameter is about 50-2000 microns, because the carrier particles are then sufficiently dense and inert enough to avoid sticking to the electrostatic image in the cascading process. Carrier particles with an average size of less than 800 microns are satisfactory for melt development.

A relatively wide range of proportions of the powder material in relation to the additional materials can be used. The friction reducing material should be · in at least sufficient amount to form an adherent film, substantially evenly distributed over at least 20% of the image surface during cyclical use of this image surface. Preferably, approximately 10% of the image surface will be covered by the friction reducing material. It was found that about 0.01 - 10% by weight of the friction reducing agent relative to the powder material was needed to obtain the coverage level mentioned above. The particularly preferred ratio is about 0.1 - 2.0% by weight of the friction reducing agent in relation to the weight of the developing powder.

It was determined that the abrasive should be in an amount sufficient to maintain the layer thickness of the friction reducing material within sub-micron boundaries, i.e. below 10.00 A, in order to avoid the formation of an interier layer. However, this amount relative to the friction reducing material must be sufficiently low that it does not remove the layer of deposited friction reducing material or prevents the formation of this layer.

If the relative amount is so large that the film is not formed or not retained, the abrasive will act directly on the photoreceptor, which in the long run can shorten the durability of the photoreceptor and some cleaning agents . It should be assumed that the image surface must have a layer of friction reducing material at least about 5 A. The ratio of the amount of both additives can be optimally determined by controlling the thickness of the remaining layer of friction reducing material. The use of a radioactive indicator in friction reducing material is an excellent means of optimizing the ratio of both additives. The length of working time should also be taken into account. In general, it has been found that the expected results are obtained using amounts of abrasive of about 0.01-10% by weight based on the weight of the powder, preferably 0.1-2®% by weight of the abrasive based on the powder.

The examples below illustrate the subject of the invention. Part and percentages, if not stated otherwise · are given by weight. The control examples are intended to illustrate the selected application of the present invention.

Example · control I. The developer control sample, consisting of 2 parts of developing powder made of colored polystyrene resin, with an average particle size of about 12 microns mixed with 100 parts of carrier balls of steel shot, about 125 microns in size, was tested.

For this purpose, the drum, from amorphous selenium, automatic copying machines charged by corona discharge to a positive potential of about 800 V and exposed to an image consisting of lights and shadows to create an electrostatic latent image. The selenium drum was then rotated in a device with a magnetic developing brush. After developing the electrostatic image 'latent in the developing device, the resulting powder image' was transferred to a sheet of paper in the copying device. · Powder particles remaining on the selenium drum after it passed through the image transfer device were removed by three different methods. A pure selenium drum was used in this and in further examples.

The first method used to clean the drum was a cylindrical * brush 10 cm in diameter, made of 15 den polystyrene fibers, about 9 mm high, with a fiber density of about 9,350 Amm *. The brush was positioned relative to the drum so that the play between the fibers and the drum surface was. 2.4 mm,. the brush performed about 175 drum laps per minute. The quality of the first copy was excellent, however, after 25,000 copies, the optical density of the background was very high, the resolution visibly dropped, the image was blurred, the line was not reproduced correctly, and the edge sharpness was poor. . Visual inspection of the drum revealed slight signs of wear and significant buildup of developing powder on the drum surface.

The second method used to clean the drum was a fabric of the type described in US Pat. United States No. 31.86858. A non-woven artificial silk fabric was used as the fabric with a pressure of about 1.3 kg / cm², the relative fabric speed relative to the photoreceptor was about 3.6 cm / second and the contact path length was about 3 mm. After repeating the copying process about 5,000 times, the copies showed good contrast and a small background residue. However, the large surfaces of the image looked faded. The micrographic examination of the drum surface showed a significant build up of the film formed from the developing powder.

In the third method of cleaning, the scraper was trampled to remove residual powders. A rectangular piece of polyurethane, similar to 1.5 mm thick rubber, one end of which was chamfered creating a cleaning hole inclined at an angle of about -60 ° parallel to the axis of the drum. The chamfered edge of the blade is positioned in relation to the moving drum in a position resembling cutting rather than wiping.

The resulting vertical force, used to press the entire blade against the drum surface, was about 1.35 kg on a spring scale. The first copies showed good quality in every respect, however, after making about 2,000 copies, the image stood still. clearly worse,. showed high optical density of the background, large planes were insufficiently covered, resolution decreased. Drum examination revealed significant build up of developing powder on the photoreceptor surface. The above tests illustrate. difficulties encountered when using typical powder material, which is characterized by a high tendency to build up on the photoreceptor. Increasing accumulation is undoubtedly the cause of a decrease in copy quality.

Control Example II. The developer control sample used in Example 1 was modified so that 0.1 part per zinc stearate with a particle size of 0.75 - 40 microns was gently added for 1 part of developing powder.

The resulting mixture was ground for 10 minutes in a Szegvari mill. After transferring the developed image as described in Example 1, a scraper was used. and a cleaning technique according to example I with the difference that a force of about 90 grams was applied to the scraper. After about 2,000 cycles, the copies were characterized by a high optical density of the background and high sediment buildup · When observed on the drum surface. selenium has been found to have excessive film build up.

This film was. formed either from zinc stearate or from a mixture of this stearate and developing powder. Through . increasing the strength of the blade relative to the photoreceptor to about 1.35 kg copy quality. remained very good for about 2,000 cycles.

This example illustrates that by using appropriate friction-reducing material in the developer, i.e., zinc stearate, together with a device transmitting sufficient strength during cleaning, control of harmful film build-up has been achieved.

The following examples show that by using a two-component abrasive additive together with a film-forming lubricant, extremely high-quality knuckle copies are obtained to more effectively control film build-up.

Example III. The developer was prepared as described below. For developing powder used. in example I, consisting of. 0.25% zinc stearate was added from a 12 micron colored polystyrene resin and milled in a Szegvari mill for 10 minutes. 1.0% by weight of purified silicon dioxide was then added in submicron grinding and milled for a further 10 minutes. Purified silicon dioxide was obtained by flame hydrolytic decomposition of silicon tetrachloride in a gas phase in a hydrogen oxyhydrogen flame at 1100^ABOUTC and the next reaction with dimethyl dichlorosilane in a heated fluidized bed reactor.

About 75% of the groups reacted in the silane fluidized bed reactor. silanol on the surface of freshly prepared silicon dioxide. Silicon dioxide particles containing approximately 3 silanol groups on 100a2 surface reacted particularly easily with silane. Analysis of the final product showed 99.8% silicon dioxide and small amounts of carbon, chlorine, heavy metals, ferric trioxide, titanium dioxide and nitrogen trioxide. The particle size was 10-30 millimicrons and the surface area was about 90-150 m2 / g.

The relative friction coefficient values ​​specified above. by technique, they were 5.23 selenium, 3.92 developing powder and 0.67 zinc stearate. The developing powder had a hardness determined on the Shore hardness tester greater than 100 on the A scale, and B zinc stearate 66 on the A scale and 52 on the B scale. The purified silicon dioxide had a hardness of about 5 on the Mohs scale. After transferring the developed image as described in Example 1, the cleaning with the scraper used in Example 1 was applied, using a pressure of about 1.35 kg. After 2,000 cycles, the copies were characterized by the same extremely high. image quality, such as initial copies. Inspection of the selenium drum found film deposition thinner than 3 grubości ·

Screaming ad IV. The procedure was similar to that described in Example 3, with the difference that the two-component additive consisted of 0.25% cadmium stearate with a particle size of 10-20 microns and 1.0% Kaophile 2,. commercially available hydrophobic aluminum silicate with a particle size of 200 millimicrons. The friction coefficient of cadmium stearate 'was 0.25 and the hardness measured with a Shore hardness tester was 78 on A scale and 66 on B scale. After 2000 cycles, this developer produced extremely good quality copies in every respect. The deposition of the film on the photoreceptor did not exceed 500A.

Example V. An analogous procedure to that described in Example 3 was followed, with the difference; 'that the two component additive consisted of 0.25% glycerol monostearate and 1.0% purified SiO2 according to example III. The friction coefficient of glycerol monostearate was 1.57, and the hardness measured with a Shore hardness tester was 67 on the A scale and 31 on the B scale. After 2000 cycles, this developer produced copies of outstanding quality in every respect. Film deposition on the photoreceptor did not exceed 3ΟθΑ ·

Example VI. The procedure was similar to that described in Example III, except that the two-component additive consisted of 4.0% e-Carbowax 4000, commercially available polyethylene glycol with a molecular weight of about 4,000 and a particle size of about 2 - 14 microns and 6.0% Aerosil R 972. Aerosil R 972 is a commercially available material, substantially identical to the purified silica according to 'Example III. The Carbowax 4000 friction coefficient was 1.63 and the hardness on the scale - A of the Shone hardness tester^,a was 95. Residual developer material remaining on the selenium drum after the drum passed through the transfer device was removed by a rotating brush and vacuum system. After 2000 cycles, this developer gave copies of excellent quality. Film deposition on the photoreceptor did not exceed 700A ·

Example VII. The procedure was analogous to that described in Example 3, with the difference that the two-component additive consisted of 0.25% cholesterol and 1.0% Aerosil R 972. Cholesterol had a particle size of 5 - 140 microns, a friction factor of 2.1 and a hardness of 72 on the B scale of the Shore hardness tester. After 2000 cycles, excellent quality copies were obtained. Film deposition on the photoreceptor did not exceed 300A.

Example VIII. The procedure was analogous to that described in Example 3, except that the two-component additive consisted of 0.25 *% PC1-150 commercially available polycaprolactone with a molecular weight of about 4.000, and with 1% Aerosil R 972 PCI-150 had particles with size 2 - 140 microns, friction coefficient 2.0 and hardness 95 on the A scale of the Shore hardness tester. After 2000 cycles, this developer gave extremely high quality copies in every respect. Film deposition on the photoconductor did not exceed 300A ·

Example IX. The procedure was analogous to that described in Example -III · with the difference that the two-component additive consisted of 0.25% 'Vydax' of a low molecular weight waxy telemetry having lubricating properties. This is a tetrafluoromethylene telomer produced by SI DuPont. The second component was Aerosil R '972 in an amount of 1.0%' Vydax 'with a particle size of 2 to 100 microns and a coefficient of friction less than the coefficient of friction⁵ powder material, hardness 72 on the B scale of a Shore hardness tester and a melting point of 300 ° C. After '2000 cycles, this developer produced copies of a quality comparable to the quality of the copies obtained in Examples 3 to 8. Residual film deposition did not exceed 300A ·

Example X. The procedure was analogous to that described in Example III except that the two-component additive consisted of 1.25 * °% terephthalic acid and 1.0% Aerosil R 972. · Acid

15, terephthalic had a coefficient of friction · 0.40 with a hardness on the Shore'ax hardness scale of 96 · This developer after 2000 cycles also gave a copy of a quality comparable to that of · copies according to examples III - VIII. Residual film placement o20 did not exceed 400A ·

Example XI. The procedure was analogous to that described in Example 3 except that the two-component additive consisted of 0.25% perchloropentacyclodecane and 1% titanium dioxide.

²⁵ Perchloropentacyclodecane had a friction factor of 1.0 and a hardness of 87 on the B scale of a Shore hardness tester. Titanium dioxide had an average particle size of about 30 millimicrons. This developer, after 2000 cycles, gave quality copies³⁰ comparable to copy quality according to examples 3 - 8. Residual film deposition did not exceed 300A ·

Example XII. The procedure was analogous to that described in Example 3 with this difference³⁵ that the two-component additive consisted of 0.25% stearyl alcohol and 1.0% antimony trioxide. Stearyl alcohol had a friction coefficient lower than the friction coefficient of the developing powder and hardness measured with a Shore hardness tester⁴⁰ less than powder hardness. The antimony trioxide powder had an average particle size of 100 microns. This developer, after 2000 cycles, gave copies of a quality comparable to the quality of copies according to examples III - · VIII. residual⁴⁵ film deposition did not exceed 400A Example XIII. The procedure was similar to that described in Example 3, except that the two-component additive consisted of 0.25% zinc stearate and 1.0 * °% crude dioxide⁵⁰ to silicon in submicron fragmentation. The addition of silicon was identical to the silicon dioxide used in Example 3, but with the difference that it was not subjected to a process that gives it organophilic properties. The process was carried out⁵⁵ at around 80% relative humidity and average temperature 24 ° C. In - initial copies, the background optical density, resolution, edge sharpness - were good. However, after making about 9,000 copies, the background optical density doubled,⁶⁰ resolution has decreased, edge sharpness has become poor. Inspection of the photoreceptor revealed a cloudy, moist, clayey film that could not be removed by the usual cleaning techniques.

The same process, carried out at humidity

-055 relative 30% and a temperature of about 24 ° gave perfect copies after about 2000 cycles. No clay film was seen on the photoreceptor surface.

If the developer used the prepared silicon dioxide according to example 3 and the process was carried out at a relatively high humidity of 60% and a temperature of 24 ° C, the image quality remained excellent and no colloidal silica deposit was noticed on the photoreceptor.

It is believed that unprocessed silica with a highly developed surface - acts as a drying agent and the water absorbed by it is harmful to the entire development and cleaning process. However, this activity is not observed if the process is carried out in low humidity conditions. .

Example XIV. The procedure was analogous to that described in Example 3 except that reversible development was used. Approximately 100 parts of 250 micron steel shot with particles coated with a mixture of polyvinyl chloride copolymer and polyvinyl acetate with Luxol Fast Blue, a commercially available dye, mixed with 1 part of the developing powder consisting of 65% polystyrene, 35% polyethylene n-butyl and 10% of soot. This reversible developer also contained, in addition to the zinc stearate of Example 2, also 1.0% by weight of alumina based on the weight of the developer powder. The average particle size of alumina was 30 millimicrons. Effective evocation took place in places without a charge on the image surface. After 1000 cycles, the copies were excellent in every respect. Thickness of developer residue on the imaging surface did not exceed 300A

Example XV The procedure was analogous to that described in Example 3, except that Q, 25% copper stearate was used instead of zinc stearate. The coefficient of friction of copper stearate was less than the coefficient of friction of the developing powder, and the hardness measured with a Shore hardness tester was less than the hardness of that powder. After 2000 cycles, this developer gave good copies in all respects.