Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G13/00—Electrographic processes using a charge pattern
  • G03G13/20—Fixing, e.g. by using heat
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G9/00—Developers
  • G03G9/08—Developers with toner particles
  • G03G9/097—Plasticisers; Charge controlling agents
  • G03G9/09708—Inorganic compounds
  • G03G9/09716—Inorganic compounds treated with organic compounds

Definitions

• the present invention relates to a toner composition suited for development of electrostatic charge images or magnetic patterns and for Direct Electrostatic Printing. It also relates to an electrostatographic method for imaging with a dry toner particles, wherein the toner image is fixed to a final substrate by a non-contact fusing process.
• Electrostatic printing methods are manifold, e.g. Direct Electrostatic Printing, wherein electrostatic printing is performed directly from a toner delivery means on a receiving substrate, the latter not bearing any imagewise latent electrostatic image, by means of an electronically addressable printhead structure.
• electrostatic printing toner images are made on an image-forming element in the form of a rotating drum provided with an electrostatic layer built up from a number of controllable electrodes in and beneath a dielectric layer.
• the voltage that is image-wise applied to said controllable electrodes attracts charged toner particles from a toner source.
• an electrostatic latent image is formed by the steps of uniformly charging a photoconductive member and imagewise discharging it by an imagewise modulated photo-exposure.
• an electrostatic latent image is formed by imagewise depositing electrically charged particles, e.g. from electron beam or ionized gas onto a dielectric substrate.
• the obtained latent images are developed, i.e. converted into visible images by selectively depositing thereon light absorbing particles, called toner particles, which usually are triboelectrically charged.
• the visible image of electrostatically or magnetically attracted toner particles is not permanent and has to be fixed by causing the toner particles to adhere to each other and the substrate by softening or fusing them followed by cooling. Normally fixing proceeds on more or less porous paper by causing or forcing the softened or fused toner mass to penetrate into the surface irregularities of the paper.
• Dry-development toners essentially comprise a thermoplastic binder consisting of a thermoplastic resin or mixture of resins (ref. e.g. US-P 4,271,249) including colouring matter, e.g. carbon black or finely dispersed dye pigments.
• the triboelectrically chargeability is defined by said substances and may be modified with a charge controlling agent.
• Dry-development toners can be of various types. It can be magnetic toner particles, used as such in a mono-component dry developer, it can also be non-magnetic particles being used as such in a non-magnetic mono-component developer or being mixed with magnetic carrier particles to form a two-(multi-)component dry developer.
• EP-A 479 875 it is disclosed to blend hydrophobic silica with small (diameter lower than 7 ⁇ m) toner particles wherein the silica is characterised by a product of methanol value (degree of hydrophobicity) and BET surface.
• the mixing proceeds in such a way that a determined ratio between apparent density and bulk density of the toner composition is reached.
• the aim of that disclosure is to improve the fluidity of small toner particles.
• the use of two different types of hydrophobic additives is described, one being hydrophobized silica, the other being hydrophobized titania.
• the teachings of said application are directed to an electrostatic imaging process wherein the toner particles are fixed upon a final substrate by heat and pressure (by a hot pressure roller).
• JP-A 62/129866 the use of a silica additive together with non-silica inorganic additives is described in a very general way over a very broad range of concentrations as a way to stabilise positive chargeability in a multi-component developer. It is taught that the concentration of the silica should be smaller than that of the other inorganic additive and that the relative proportion of the silica to the other additive is in the range of 0.01 to 0.50.
• a mono-component developer i.e.
• a developer without magnetic carrier particles has been disclosed wherein two different types of inorganic particles, one type with a BET surface between 0.2 and 30 m 2 /g, preferably between 1.0 and 6.0 m 2 /g and one with a BET surface between 40 and 400 m 2 /g, are also present.
• the particles with low BET are preferably hard and are strontium titanate or cerium oxide.
• an electrophotographic toner is disclosed containing a colorant and a binder resin also containing fine SiO 2 powder with an average particle size of maximum 0.1 ⁇ m and TiO 2 particles with an average size of minimum 0.1 ⁇ m.
• the inorganic particles are adhered on the surface of the toner particles.
• toner particles minimises blurring (e.g. poor toning and satellite formation), due to the formation of toner with opposite charge. It can be used with or without a carrier.
• the fusing in the patent cited proceeds by a hot roller fuser, being a contact fuser.
• a fine toner is described, for a full-colour system.
• a mixture of both a inorganic hydrophobic additive and an inorganic hydrophillic additive is described.
• the use of a hydrophillic additive in the toner composition will impede proper melting of the hydrophobic binder of the toner and hence good interpenetration during the melt-fixing step, when no additional forces are used, such as in a non-contact fusing process.
• the described toner is used in a fusing system using heat and pressure, the electrophotographic device containing a hot roller fusing system.
• One of the quality parameters of an image formed by dry toner particles is the gloss of the final image.
• Methods for producing toner images using non-contact fusing steps are often preferred, since the drawbacks (hot-offset, addition of silicone oil with detrimental influence on gloss) of hot-roller fixing are avoided.
• the toner resins are to be designed low viscous in behaviour above the softening point of the toner. This implies that the toners have the tendency to interflow very good and to offer rather smooth surfaces, thus giving a rather high gloss.
• the single layers are conforming to the paper and offer a less smooth image.
• the bi-, ter- and quadruple layers are however more glossy. Therefore there is apart from a rather glossy appearance the problem of gloss differences depending on thickness.
• the objects of the invention are realized by providing a toner composition comprising toner particles and number n of different types of hydrophobic inorganic particles, characterised in that
• the BET surface of both toner particles and hydrophobic inorganic particles can be measured by a method described by Nielsen and Eggertsen in "Determination of Surface Area Adsorption measurements by continuous Flow Method", Analytical Chemistry, Vol. 30, No. 9 (1958) p. 1387-1390.
• Toner particles with a BET surface between 0.4 m 2 /g and 1.5 m 2 /m are toner particles having an average volume diameter between 10 and 3 ⁇ m.
• BET ton stands for the BET surface of the toner particles as such.
• the toner particles have a melt viscosity ⁇ between 250 and 1,500 Pa.s.
• the number n of different types of inorganic hydrophobic particles is 2 and the first type of inorganic hydrophobic particles (IP1) has a BET surface (BET ip1 ) larger than the BET surface of the second type of said inorganic particles (BET ip2 ) and each of said two types of inorganic hydrophobic particles are present in said toner composition in an amount (A 1 , A 2 ) in % by weight (% wt) with respect tot the toner particles) such that 150 ⁇ BR ⁇ 375, or more preferred 200 ⁇ BR ⁇ 330.
• each of said two types of inorganic hydrophobic particles are present in said toner composition in an amount (A 1 , A 2 in % by weight (% wt) with respect tot the toner particles) such that 0.25 % wt ⁇ A 1 + A 2 ⁇ 2.5 % wt and 0.4 ⁇ A 1 /A 2 ⁇ 2, moreover it is preferred that BET ip1 > 150 m 2 /g and BET ip2 ⁇ 150 m 2 /g. Most preferably BET ip1 ⁇ 200 m 2 /g and 30 m 2 /g ⁇ BET ip2 ⁇ 100 m 2 /g.
• said two different types of inorganic hydrophobic particles are each present in said toner composition in an amount (A 1 , A 2 in % by weight (% wt) with respect tot the toner particles) such that 0.5 % wt ⁇ A 1 + A 2 ⁇ 1.5 % wt and 0.5 ⁇ A 1 /A 2 ⁇ 1.5.
• the inorganic hydrophobic particles with the larger BET surface are hydrophobic silica particles and the inorganic hydrophobic particles with the smaller BET surface are hydrophobic titania (TiO 2 ).
• the hydrophobic titania is preferably crystalline of the rutile or anatase type.
• Suitable hydrophobic silica can be fumed silica as well as precipitated silica.
• Useful silica, for the instant invention, can be found among the different types of hydrophobic silica marketed by DEGUSSA of Germany under the trade name AEROSIL. Particularly suitable are AEROSIL R812 with BET surface of 260 m 2 /g, AEROSIL R974 with BET surface of 170 m 2 /g and AEROSIL R805 with BET surface of 150 m 2 /g, AEROSIL R202 with BET surface of 100 m 2 /g and AEROSIL R972 with BET surface of 110 m 2 /g.
• silica particles can be precipitated silica particles that are made hydrophobic.
• silica particles are available through NIPPON SILICA of Japan under trade names SILICA SS10, with BET surface of 87 m 2 /g, SILICA SS20 with BET surface of 113 m 2 /g, SILICA SS40 with BET surface of 59 m 2 /g and SILICA SS70 with BET surface of 42 m 2 /g.
• Suitable hydrophobic TiO 2 is, e.g., TITANDIOXID T805 (tradename of DEGUSSA of Germany) with BET surface of 45 m 2 /g.
• the toner compositions according to the present invention can be used in any electrostatographic printing system known in the art, electrophotography, ionography, direct electrostatic printing, etc. They are especially useful in classical electrophotography and in Direct Electrostatic Printing. When the toner particles in a composition according to this invention are magnetic they can also be used in magnetographic printing systems.
• the inorganic hydrophobic particles are simply mixed with the toner particles. It was found that, when the mixing proceeded in a way that also mechano-fusing of the particles in the toner surface appeared, (e.g. by long mixing times in an HENSCHEL mixer at temperatures higher than room temperature), the effect on gloss control was essentially the same as when the inorganic particles were simply mixed with the toner particles.
• the toner particles can comprise any toner resin known in the art and any known pigment or dye as long as said toner particles have a melt viscosity ⁇ such that 150 Pa.s (1,500 poise) ⁇ ⁇ ⁇ 2,000 Pa.s (20,000 poise).
• the toner particles Preferably have a melt viscosity ⁇ such that 250 Pa.s (2,000 poise) ⁇ ⁇ ⁇ 1,500 Pa.s (15,000 poise).
• melt viscosity of the toner particles were quite critical. Too low melt viscosity (below 150 Pa.s) resulted in good fixing, but also in too high gloss that not could be diminished by the addition of different types of hydrophobic inorganic particles to the toner particles. Toner particles with too high melt viscosity (over 2,000 Pa.s) could not be properly fixed in a non-contact fusing process.
• toner resin for toner particles useful in this invention is primarily chosen with emphasis on its melting behaviour, but also the other properties as chargeability, hardness, etc have to be considered.
• the toner resin can be a polycondensation polymer or a mixture of polycondensation polymers as well as an addition polymer or a mixture of addition polymers. Also mixtures of polycondensation polymers and addition polymers are suitable as toner resin for toner particles according to the present invention. When polycondensation polymers are used, the use of polyesters is preferred.
• Polyester resins suitable for use in toner particles according to the present invention are selected e.g. from the group of linear polycondensation products of (i) di-functional organic acids, e.g. maleic acid, fumaric acid, terephthalic acid and isophthalic acid and (ii) di-functional alcohols (diol) such as ethylene glycol, triethylene glycol, an aromatic dihydroxy compound, preferably a bisphenol such as 2,2-bis(4-hydroxyphenyl)propane called "Bisphenol A” or an alkoxylated bisphenol, e.g. propoxylated bisphenol examples of which are given in US-P 4,331,755.
• di-functional organic acids e.g. maleic acid, fumaric acid, terephthalic acid and isophthalic acid
• di-functional alcohols diol
• diol such as ethylene glycol, triethylene glycol, an aromatic dihydroxy compound, preferably a bisphenol such as 2,2-bis(4-hydroxyphenyl)propan
• styrene/acrylic resins When addition polymers are used, it is preferred to use styrene/acrylic resins.
• Preferred styrene-acrylic resins have a relatively high (more than 70 mol %) styrene content, and are more particularly copolymers of styrene-acrylic resins or styrene-methacrylic resins, e.g. copoly(styrene/n-butylmethacrylate) or copoly(styrene/2-ethyl-hexylacrylate).
• Typical useful resins for the toner resin in toner particles according to the present invention are tabulated in table 1.
• TABLE 1 N o Polymer Tg °C Meltvisco Pa.s 1 Polyester P1 50,5 140 2 Polyester P2 65 550 3 Polyester P3 63 700 4 Polyester P4 69 1600 5 Styr/acryl S1 67 1700 6 Styr/acryl S2 68 285 7 Styr/acryl S3 78 170 8 Styr/acryl S4 79 290 9 Styr/acryl S5 79.5 700 10 Styr/acryl S6 79 2250 Polyester P1 is ATLAC T500 (tradename).
• Polyester P2 is an aromatic polyester resin derived from terephthalic acid (100 mol %) as aromatic diacid and a mixture of DIANOL 33 (50 mol %) and ethylene glycol (50 mol %) as diols.
• Polyester P3 is an aromatic polyester resin derived from terephthalic acid (40 mol %), isophthalic acid (60 mol %) as aromatic di-acids and a mixture of DIANOL 22 (40 mol %) and ethylene glycol (60 mol %).
• DIANOL 22 is di-ethoxylated Bisphenol A.
• DIANOL 33 is di-propoxylated Bisphenol A.
• Bisphenol A 4,4'isopropylidenediphenol.
• Polyester P4 is an aromatic polyester resin derived from terephthalic acid (64 mol %), isophthalic acid (36 mol %) as aromatic di-acids and ethylene glycol (100 mol %).
• Styr/acryl S1 is a copolymer of styrene and methyl acrylate in a 65/35 molar ratio.
• Styr/acryl S2 is a terpolymer of styrene, methyl acrylate and dimethylaminoethyl methacrylate in a 87/3/10 molar ratio.
• Styr/acryl S3, S4, S5 and S6 are a copolymer of styrene and methyl acrylate in a 80/20 molar ratio, only differing in molecular weight.
• resins for use in toner particles have been disclosed in US 5,395,726, that is incorporated herein by reference.
• the resins disclosed in said patent and comprised in a toner composition according to the present invention are a mixture of resins, resin A and at least one resin B, characterized in that :
• the toner particles comprise a resin mixture of at least two resins being selected in such a way that they have slight incompatibility with respect to each other.
• the HILDEBRAND parameter solubility for polymers is described in the book “Properties of Polymers” by D.W. Van Krevelen, 2nd. ed., Elseviers Scientific Publishing Company, New York, 1976, Chapter 7.
• the combination of the inorganic particles according to the present invention with toner particles comprising a resin mixture of at least two resins being selected in such a way that they have slight incompatibility with respect to each other, offers a useful method for gloss control.
• the desired slight incompatibility can be obtained by combining a polyester resin P1 from table 1, e.g. a polyester, with an other polyester P2 from table 1, having a more polar character than said polyester resin P1.
• a polyester resin P1 from table 1 e.g. a polyester
• an other polyester P2 from table 1 having a more polar character than said polyester resin P1.
• Such mixtures of resins and of resins and incompatible compounds have been disclosed in EP-A 656 129, which is incorporated herein by reference.
• the toner resin of toner particles according to the present invention can comprise more than 3 % by weight with respect to the total resin content or can consist of a polysiloxane modified resin comprising polysiloxane moieties (PS) and other polymeric moieties (POL).
• PS polysiloxane moieties
• POL polymeric moieties
• toner particles used in toner compositions according to the present invention, comprise as toner resin amorphous complex macromelecular compound that comprises in its macromelecular structure, (i) an amorphous polycondensation backbone, the corresponding backbone polymer having a Tg of at least 45 °C and (ii) at least one polymer chain being attached to said backbone, either terminally and/or in a side-chain, said polymer chain being derived from a polymer which on itself has an average molecular weight by number (M avg ) so that 400 ⁇ M avg ⁇ 4,000, a melting point between 50 °C and 150 °C and a melting range of at most 15 °C.
• Such resins and toner particles comprising them are disclosed in EP-A 712 881, that is included herein by reference.
• the toner particles, incorporated in a toner composition according to this invention can be magnetic particles, incorporating a magnetic pigment, or can, preferably be non-magnetic.
• the non-magnetic toner particles in a toner composition according to this invention can beneficially be used in a two- (or multi) component developer, comprising a toner composition according to this invention together with magnetic carrier particles.
• Toner particles used in a toner composition according to the present invention, can have an average volume diameter between 1 and 50 ⁇ m, preferably between 3 and 20 ⁇ m. When the toner particles are intended for use in colour imaging, it is preferred that the volume average diameter is between 3 and 10 ⁇ m, most preferred between 3 and 8 ⁇ m.
• the particle size distribution of said toner particles can be of any type. It is however preferred to have an essentially (some negative or positive skewness can be tolerated, although a positive skewness, giving less smaller particles than an unskewed distribution, is preferred) Gaussian or normal particle size distribution, either by number or volume, with a coefficient of variability (standard deviation divided by the average) ( ⁇ ) smaller than 0.5, more preferably of 0.3.
• Toner particles used in toner compositions according to the present invention, can comprise any normal toner ingredient e.g. charge control agents, pigments both coloured and black, anorganic fillers, etc.
• charge control agents e.g. charge control agents, pigments both coloured and black, anorganic fillers, etc.
• a description a charge control agents, pigments and other additives useful in toner particles, to be used in a toner composition according to the present invention, can be found in e.g. EP-A 601 235.
• the images formed by deposition of a toner composition according to the present invention are preferably fixed in a non-contact fusing process.
• a non-contact fusing process includes a variety of embodiments, such as : (1) an oven heating process in which heat is applied to the toner image by hot air over a wide portion of the support sheet, (2) a radiant heating process in which heat is supplied by infrared and/or visible light absorbed in the toner, the light source being e.g. an infrared lamp or flash lamp, (3) a process wherein the heat is transferred to the toner layer by heating the side of the substrate opposite to the side carrying the image.
• This last process can be implemented in a non-contact system as well as by contacting said side opposite to the side carrying the image by heating means, e.g., a heated roller.
• heating means e.g., a heated roller.
• the non-contact fusing systems described above under (1) and (2) are preferred.
• this invention includes the use of toner compositions according to this invention in an electrostatographic method containing a non-contact fusing step, especially in those electrostatographic methods wherein said non-contact fusing step proceeds essentially by Infra Red (IR) radiation and optionally hot air.
• IR Infra Red
• the invention thus includes also a method for electrostatographic imaging comprising the steps of :
• the invention also encompasses a method for gloss control in electrostatically formed images comprising the steps of
• the amount and/or the dispersion of pigment in the toner particles, for a single colour is adjusted such that a full saturated density in said colour is achieved by the deposition of a thin, almost single, layer of toner particles.
• the amount of toner particles (Toner Mass, TM) being deposited to reach maximum optical density for each of the single colours follow the equation : TM ⁇ 0.8 ⁇ d v50 ⁇ ⁇ wherein TM is expressed in mg/cm 2 , d v50 is the average volume diameter of the toner particles expressed in cm, and ⁇ is the bulk density of the toner particles in mg/cm 3 .
• maximum optical density for each of the single colours is meant an optical density on a reflecting support between 1.4 and 1.6 for yellow, magenta and cyan and an optical density between 1.6 and 2.0 for black.
• the invention also encompasses a toner composition, comprising toner particles and number n of different types of hydrophobic inorganic particles, characterised in that
• polyester P1 of Table 1 and 49 parts of polyester P3 of Table 1 were melt-blended for 30 minutes at 110 °C in a laboratory kneader with 2 parts of Cu-phthalocyanine pigment (Colour Index PB 15:3).
• the solidified mass was pulverized and milled using an ALPINE Fliessbettarnastrahlmühle type 100AFG (tradename) and further classified using an ALPINE multiplex zig-zag classifier type 100MZR (tradename).
• the melt viscosity of the toner particles was 400 Pa.s as measured in a plate/plate rheometer (CARIMED RHEOMETER CSL 500 trade name of TA instruments Ltd, Dorking UK) at 120 °C and 100 rad/s.
• polyester P1 of Table 1 98 parts were melt-blended for 30 minutes at 110 °C in a laboratory kneader with 2 parts of Cu-phthalocyanine pigment (Colour Index PB 15:3).
• the solidified mass was pulverized and milled using an ALPINE Fliessbettarnastrahlmühle type 100AFG (tradename) and further classified using an ALPINE multiplex zig-zag classifier type 100MZR (tradename).
• the melt viscosity ( ⁇ ) of the toner particles was 150 Pa.s.
• the solidified mass was pulverized and milled using an ALPINE Fliessbettarnastrahlmühle type 100AFG (tradename) and further classified using an ALPINE multiplex zig-zag classifier type 100MZR (tradename).
• the melt viscosity ( ⁇ ) of the toner particles was 2300 Pas.
• Toner 1 (T1), and one type inorganic hydrophobic particles were mixed using a HENSCHEL mixer with a filling factor of 30 % by volume, rotational speed 35 m/sec and during 30 sec.
• the inorganic hydrophobic particles were hydrophobic fumed SiO 2 particles with specific surface area of 110 m 2 /g (AEROSIL R972).
• the inorganic hydrophobic particles were added to the toner composition at a concentration of 1 parts for 100 parts of toner particles.
• toner preparation TC1 was repeated, except that fumed hydrophobic SiO 2 with a specific surface area of 170 m 2 /g (AEROSIL R974) was mixed with the toner particles at a concentration of 1 part for 100 parts of toner particles.
• fumed hydrophobic SiO 2 with a specific surface area of 170 m 2 /g AEROSIL R974
• toner composition TC1 was repeated, except that fumed hydrophobic SiO 2 with a specific area of 260 m 2 /g (AEROSIL R812) was added in a concentration of 1 part for 100 parts of toner particles.
• fumed hydrophobic SiO 2 with a specific area of 260 m 2 /g AEROSIL R812
• toner composition TC1 was repeated except for concentration of the hydrophobic silica, which was now 0.5 parts for 100 parts of toner particles.
• toner composition TC1 The preparation of toner composition TC1 was repeated except that NO hydrophobic inorganic particles were present.
• toner composition TC1 was repeated, except that hydrophobic precipitated SiO 2 with a specific area of 113 m 2 /g (SILICA SS20) was added in a concentration of 1 part for 100 parts of toner particles.
• hydrophobic precipitated SiO 2 with a specific area of 113 m 2 /g (SILICA SS20) was added in a concentration of 1 part for 100 parts of toner particles.
• toner composition TC1 was repeated, except that hydrophobic precipitated SiO 2 with a specific area of 42 m 2 /g (SILICA SS70) was added in a concentration of 1 part for 100 parts of toner particles.
• hydrophobic precipitated SiO 2 with a specific area of 42 m 2 /g (SILICA SS70) was added in a concentration of 1 part for 100 parts of toner particles.
• toner composition TC1 The preparation of toner composition TC1 was repeated except that two types of inorganic hydrophobic particles were present. Hydrophobic fumed SiO 2 particles with specific surface area of 260 m 2 /g (AEROSIL R812) and hydrophobic precipitated SiO 2 particles with a specific surface area of 42 m 2 /g (SILICA SS70) were each added to the toner composition at a concentration of 0.5 part versus 100 parts of toner particles.
• AEROSIL R812 hydrophobic fumed SiO 2 particles with specific surface area of 260 m 2 /g
• SILICA SS70 hydrophobic precipitated SiO 2 particles with a specific surface area of 42 m 2 /g
• toner composition TC1 The preparation of toner composition TC1 was repeated except that two types of inorganic hydrophobic particles were present. Hydrophobic fumed SiO 2 particles with specific surface area of 260 m 2 /g (AEROSIL R812) and hydrophobic precipitated SiO 2 particles with a specific surface area of 113 m 2 /g (SILICA SS20) were each added to the toner composition at a concentration of 0.5 part versus 100 parts of toner particles.
• AEROSIL R812 hydrophobic fumed SiO 2 particles with specific surface area of 260 m 2 /g
• SILICA SS20 hydrophobic precipitated SiO 2 particles with a specific surface area of 113 m 2 /g
• toner composition TC1 The preparation of toner composition TC1 was repeated except that two types of inorganic hydrophobic particles were present. Hydrophobic fumed SiO 2 particles with specific surface area of 260 m 2 /g (AEROSIL R812) and hydrophobic TiO 2 particles with a specific surface area of 50 m 2 /g (TITANDIOXID T805) were each added to the toner composition at a concentration of 0.5 part versus 100 parts of toner particles.
• toner composition TC10 was repeated except that each of the two types of hydrophobic inorganic particles was present for 0.3 parts for 100 parts of toner particles.
• toner composition TC10 was repeated except that fumed hydrophobic silica (AEROSIL R812) was present for 0.5 parts for 100 parts of toner particles and hydrophobic TiO 2 (TITANDIOXID T805) for 0.7 parts for 100 parts of toner particles.
• fumed hydrophobic silica AEROSIL R812
• hydrophobic TiO 2 TITANDIOXID T805
• toner composition TC10 was repeated except that fumed hydrophobic silica (AEROSIL R812) was present for 0.45 parts for 100 parts of toner particles and hydrophobic TiO 2 (TITANDIOXID T805) for 0.65 parts for 100 parts of toner particles.
• AEROSIL R812 fumed hydrophobic silica
• TITANDIOXID T805 hydrophobic TiO 2
• toner composition TC10 was repeated except that instead of fumed hydrophobic silica (AEROSIL R812), fumed hydrophobic silica with BET surface 170 m 2 /g (AEROSIL R974) was used.
• fumed hydrophobic silica AEROSIL R812
• fumed hydrophobic silica with BET surface 170 m 2 /g AEROSIL R974
• toner composition TC14 was repeated except that instead of hydrophobic titania (TITANDIOXID T805), precipitated hydrophobic silica with BET surface 42 m 2 /g (SILICA SS70) was used.
• hydrophobic titania TITANDIOXID T805
• precipitated hydrophobic silica with BET surface 42 m 2 /g SILICA SS70
• toner composition TC10 was repeated except that toner T2 was used.
• toner composition TC10 was repeated except that toner T2 was used.
• a multi-component developer was prepared by mixing each composition to a coated ferrite carrier with a volume average particle size of 50 ⁇ m, at a concentration of 5% toner weight with resect to the carrier and activated for 30 minutes in order to attain a stable charge level.
• optical density (a measure of amount of transferred toner mass) was evaluated and ranked according to the following ranking figures :

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• 1997
  • 1997-03-20 EP EP97200834A patent/EP0801333A3/de not_active Withdrawn
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