Classifications

• • 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
• • 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
  • G03G9/09733—Organic compounds
  • G03G9/09741—Organic compounds cationic
• • 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
  • G03G9/09733—Organic compounds
  • G03G9/0975—Organic compounds anionic

Definitions

• the present invention relates to the use of special aryl and aralkyl sulfide, sulfoxide or sulfone compounds as charge control agents in electrophotographic toners and developers and as charge control agents in powders and powder coatings for surface coating.
• the compounds according to the invention have particularly high and constant charge control effects and are distinguished by the simplicity of the synthesis components and the production process. Furthermore, these compounds have very good temperature stability and dispersing properties.
• a "latent charge image” is generated on a photoconductor. This is done, for example, by charging a photoconductor by means of a corona discharge and then imagewise exposing the electrostatically charged surface of the photoconductor, the exposure of the charge to the grounded base at the exposed locations being effected by the exposure.
• the "latent charge image” thus generated is then developed by applying a toner.
• the toner is transferred from the photoconductor to, for example, paper, textiles, foils or plastic and is fixed, for example, by means of pressure, radiation, heat or the action of solvents.
• the photoconductor used is then cleaned and is available for a new recording process.
• toners The optimization of toners is described in numerous patents, including the influence of the toner binder (variation of resin / resin components or Wax / wax components), the influence of carriers (for two-component developers) and magnetic pigments (for one-component developers) are examined.
• a measure of the toner quality is its specific charge q / m (charge per mass unit).
• the decisive factor in quality is the rapid achievement of the desired charge level and the constancy of this charge over a longer activation period. In practice this is of central importance in that the toner in the developer mixture can be subjected to a considerable activation time before it is transferred to the photoconductor, since it remains in the developer mixture in part over a period of production of up to several thousand copies.
• Both positively and negatively chargeable toners are used in copiers and laser printers depending on the type of process and device.
• charge control agents also called charge control agents
• charge control agents are often added.
• the extent of the control effect is important, since greater effectiveness allows a small amount to be used. Since toner binders generally have a strong dependence of the charge on the activation time, it is the task of a charge control agent to set the sign and amount of the toner charge on the one hand and to counteract the charge drift of the toner binder on the other hand and to ensure constant toner charge.
• charge control agents are absolutely particularly important absolutely without their own color.
• the three toners yellow, cyan and magenta have to be exactly matched to each other in terms of their triboelectric properties in addition to the precisely defined color requirements.
• This triboelectric adjustment is necessary because in the case of full-color printing or in the case of full-color copying, the three color toners (or four color toners if black is included) must be transferred in succession in the same device.
• Colorants are known to have a lasting influence on the triboelectric charging of toners (H.-T. Macholdt, A. Sieber, Dyes & Pigments 9 (1988), 119-27; US Pat. No. 4,057,426). Because of the different triboelectric effects of colorants and the resulting, in some cases, very pronounced influence on the toner chargeability, it is not possible to simply add them as a colorant to a toner base formulation that has already been created. Rather, it may be necessary to create a separate recipe for each colorant. B. The type and amount of charge control agent required can be specially tailored. This procedure is correspondingly complex and comes in addition to those already described for color toners for process color (trichromatic) Added difficulties.
• a thermal stability of> 200 ° C, better still> 250 ° C is a great advantage. It is also important that the thermal stability is guaranteed over a longer period (approx. 30 min.) And in different binder systems. This is important because recurring matrix effects lead to premature decomposition of the charge control agent in the toner resin, which results in a dark yellow or dark brown coloration of the toner resin and the charge control effect is lost in whole or in part.
• Typical toner binders are polymerization, polyaddition and polycondensation resins such as. B. styrene, styrene acrylate, styrene butadiene, acrylate, polyester, phenol and epoxy resins, individually or in combination, which may contain other ingredients such as colorants, waxes or flow aids, or can be added afterwards.
• the charge control agent preferably has no wax-like properties, no stickiness and a melting or softening point of> 150 ° C., better> 200 ° C.
• Stickiness often leads to problems when metering in the toner formulation, and low melting or softening points could lead to the fact that no homogeneous distribution is achieved when dispersing, since the material z.
• B. combines droplet-shaped in the carrier material.
• the powder coating or powder receives an electrostatic charge in the spray device, which is opposite to the charge of the friction partner, generally a hose or spray tube (for example made of polytetrafluoroethylene).
• Epoxy resins, carboxyl- and hydroxyl-containing polyester resins, acrylic resins and polyurethanes are typically used as powder coating resins together with the corresponding hardeners. Combinations of resins are also used.
• epoxy resins are often used in combination with carboxyl- and hydroxyl-containing polyester resins.
• Typical hardener components for epoxy resins are, for example, acid anhydrides, imidazoles and dicyandiamide and their derivatives.
• Typical hardener components for polyester resins containing hydroxyl groups are, for example, acid anhydrides, blocked isocyanates, bisacyl urethanes, phenolic resins, melamine resins, and typical hardener components for polyester resins containing carboxyl groups are, for example, triglycidyl isocyanurates or epoxy resins.
• Typical hardener components used in acrylic resins are, for example, oxazolines, isocyanates, triglycidyl isocyanurates or dicarboxylic acids.
• DE-OS 3144017, JP-OS 61-236557 and US-PS 4656112 describe metal complexes and metal organyls, DE-OS 3837345, DE-OS 3738948, DE-OS 3604827, EP-OS 242420, EP-OS 203532, US- PS 4684596, US-PS 4683188 and US-PS 4493883 ammonium and Immonium compounds and DE-OS 3912396, US-PS 4496643 and US-PS 3893935 phosphonium compounds and EP-PS 185509, JP-OS 01-136166, JP-OS 63-060458, JP-OS 62-264066, US-PS 4840863 US- PS 4639043, US-PS 4378419, US-PS 4355167 and US-PS 4299898 polymeric ammonium compounds as colorless charge control agents for electrophotographic toners.
• the colorless charge control agents known hitherto have a number of disadvantages which severely restrict their use in practice or make them impossible in some cases.
• the chromium, iron, cobalt and zinc complexes described in DE-OS 3144017 and US Pat. No. 4,655,112 and the antimony organyls described in JP-OS 61-236557 also have the disadvantage, in addition to the problem of heavy metals, that they are sometimes not really colorless , and can therefore only be used to a limited extent in color toners.
• the known quaternary ammonium and phosphonium compounds, which are suitable per se, are often difficult to disperse, which leads to an uneven charging of the toner.
• the problem often arises that the toner charge generated by these compounds is not stable over a longer activation period (up to 24 hours activation time), in particular at high temperature and air humidity (EP-OS 242420), which then occurs in the course of a copying process. or printing process leads to the accumulation of incorrectly or insufficiently charged toner particles and thus brings the process to a standstill.
• ammonium and immonium based charge control agents can be sensitive to light or mechanical effects (EP-OS 203532, US-PS 4683188) and can be thermally unstable and that they form decomposition products which adversely affect the triboelectric charging of the toner can have (US-PS 4684596) and / or a strong, often dark brown, own color (DE-OS 3738948, DE-OS 3604827, US-PS 4493883). In addition, they often show wax-like Behavior, in part water solubility and / or low effectiveness as a charge control agent.
• Charge control agents which are suitable per se based on highly fluorinated ammonium, immonium and phosphonium compounds (DE-OS 3912396, DE-OS 3837345) have the disadvantage of complex synthesis, as a result of which high production costs for the corresponding substances are incurred. In addition, they are not sufficiently thermostable.
• Phosphonium salts are less effective as charge control agents than ammonium salts (US Pat. No. 4,496,643, US Pat. No. 3,893,939) and can be toxicologically problematic.
• Charge control agents based on polymeric ammonium compounds partially lead to amine odor in the toner or developer, and the charge control properties of these substances can change due to relatively easy oxidation and moisture absorption. Furthermore, the oxidation products are colored and therefore particularly troublesome in color toners (US Pat. No. 4,840,863).
• the above charge control agents for electrophotographic toners and developers are e.g. B. not suitable due to their color for use in the predominantly white or clear triboelectric or electrokinetically sprayed powders and powder coatings. Furthermore, a lack of thermal stability severely limits the use of such charge control agents, since powder coatings are baked for 15 minutes at, for example, over 200 ° C.
• the charge control agents for powders and powder coatings claimed in DE-OS 3837345 and DE-OS 3600395 are difficult to handle due to their waxiness and water solubility or hygroscopy and can only be used to a limited extent.
• the aim of the present invention was therefore to find new colorless charge control agents which have high and constant charge control effects and are distinguished by very good thermostabilities and dispersing properties.
• charge control agents should be able to be synthesized from inexpensive, readily available intermediate products by simple manufacturing processes.
• a metal ion preferably a calcium, magnesium, barium , Aluminum, chromium, manganese, iron, cobalt, nickel, copper or zinc ions, furthermore an ammonium or immonium or guanidinium ion of the general formula respectively.
• R11, R12, R13, R14 independently of one another are hydrogen atoms or a radical based on a hydrocarbon which can be interrupted by heteroatoms, such as, for. B.
• alkyl groups of 1 to 30 carbon atoms, preferably of 1 to 22 carbon atoms, oxethyl groups of the general formula - (CH2-CH2-O) n -R, where R is a hydrogen atom or an alkyl (C1-C4) group, Acyl group, such as the acetyl, benzoyl or naphthoyl group, and n is a number from 1 to 10, preferably from 1 to 4, furthermore mono- or polynuclear cyclopentyl groups, mono- or polynuclear aromatic radicals, such as phenyl, 1- Are naphthyl, 2-naphthyl, tolyl or bisphenyl radicals, or araliphatic radicals, such as, for example, the benzyl radical, the aliphatic, araliphatic and aromatic radicals being substituted by hydroxy, alkyl (C1-C4) -, alkoxy (C1-C4) groups,
• alkyl (C1-C6) - or alkoxy (C1-C6) groups which can be interrupted by heteroatoms or represent an amino group of the general formula -NR17R18, wherein R17 and R18 independently of one another are hydrogen atoms or radicals based on a hydrocarbon, preferably Are alkyl (C1-C6) groups, where R11 and R13 or R11 and R15 form a saturated or unsaturated, substituted or unsubstituted ring system with 5 to 7 atoms, the further heteroatoms, preferably nitrogen atoms and / or oxygen atoms and / or sulfur atoms, can contain, can join together (examples of such ring systems include phenylene, naphthylene, pyridine, piperidine and their derivatives) and wherein the two carboxyl or carboxylate groups -COOA and -COOB can be located at any position on the respective aromatic ring, but preferably in the 2.2 'or 3.3' or 4.4'-position to each other
• B a straight-chain or branched, saturated or unsaturated alkyl group having 1 to 30 carbon atoms, preferably having 1 to 22 carbon atoms, also alkoxylene (C1-C4) groups, polyoxalkylene groups of the general formula - [alkylene (C1-C5) -O] nR, wherein R is a hydrogen atom or an alkyl (C1-C4) group, an acyl group such as an acetyl, benzoyl or naphthoyl group, and n is a number from 1 to 10, preferably from 1 to 4, furthermore mononuclear or polynuclear cycloaliphatic radicals of 5 to 12 carbon atoms, such as, for example, a cyclopentyl or cyclohexyl radical, mono- or polynuclear aromatic radicals, such as, for example, phenyl, naphthyl, tolyl or biphenyl radicals, or an araliphatic radical, such
• the compounds claimed according to the invention can also be used as charge-improving agents in the form of coatings from carriers or as part of coatings from carriers which are used in developers of electrophotographic copiers or printers.
• the particular advantage of the compounds claimed according to the invention is that they are colorless and very thermostable and have a high charge control effect and that this is constant over a longer activation period (up to 24 hours). So shows z. B. a test toner with 1 percent by weight of the monotetrapropylammonium salt of 2,2'-dithiodibenzoic acid (2,2'-DTDB) after 10 minutes a charge of + 11 ⁇ C / g, after 30 minutes of +12 uC / g, after 2 hours of +10 uC / g and after 24 hours of +7 ⁇ C / g.
• the charge control effect is also not susceptible to changes in air humidity from 50% to 20% or to 90% (example 5).
• the high charge control effect becomes even clearer if, for comparison, e.g. B. the charging behavior of the pure toner binder "Dialec S-309" is considered (comparative example: -4 ⁇ C / g after 10 min., -12 uC / g after 30 min., -27 uC / g after 2 hours. -48 u C / g after 24 hours).
• a test powder coating in the polyester resin Crylcoat 430 shows with 1 percent by weight of the monotetrabutylammonium salt of 2,2'-DTDB or with 1 percent by weight of said 2,2′-DTDB salt and 30 percent by weight of Tiona RCL 628 (TiO2 from SCM, England) a charge of -7 or -6 ⁇ C / g after 10 minutes, of -6 or -6 ⁇ C / g after 30 minutes, of -5 or -5 ⁇ C / g after 2 hours and of -4 or -4 ⁇ C / g after 24 hours of activation time (Example 18 or Example 17), whereas the pure powder coating resin Crylcoat 430 without additional additives has a charge of -20 ⁇ C / g after 10 min., -15 ⁇ C / s after 30 min. , -8 ⁇ C / g after 2 hours and
• the compounds claimed according to the invention are chemically inert and well tolerated with binders such as. B. styrene acrylates, polyesters, epoxies and polyurethanes.
• binders such as. B. styrene acrylates, polyesters, epoxies and polyurethanes.
• the compounds can be incorporated into the common binders without difficulty using the customary processes (extrusion, kneading) under the customary conditions (temperatures between 100 ° C. and 200 ° C.).
• the synthesis of the compounds claimed according to the invention is not very expensive and the products are obtained in high purity.
• the compounds used according to the invention are generally used in a concentration of from about 0.01 to about 30 percent by weight, preferably from about 0.1 to about 5.0 Weight percent, in the respective binder in a known manner, for. B. homogeneously incorporated by extrusion or kneading.
• the compounds used according to the invention can in principle also be added during the preparation of the respective binders, ie in the course of their polymerization, polyaddition or polycondensation.
• the height of the electrophotographic toners or powder coatings, into which the charge control agents claimed according to the invention were homogeneously incorporated, was measured on standard test systems under the same conditions (such as the same dispersion times, same particle size distribution, same particle shape) at room temperature and 50% relative atmospheric humidity.
• the toner or powder coating was electrostatically charged by swirling with a carrier, ie a standardized friction partner (3 parts by weight of toner or powder to 97 parts by weight of carrier), on a roller bench (150 revolutions per minute).
• a carrier ie a standardized friction partner (3 parts by weight of toner or powder to 97 parts by weight of carrier)
• the electrostatic charge was then measured on a conventional q / m measuring stand (cf. JH Dessauer, HE Clark, "Xerography and related Processes", Focal Press, NY, 1965, page 289, or JF Hughes, "Electrostatic Powder Coating” , Research Studies Press Ltd., Letchworth, Hertfordshire, England, 1984, Chapter 2).
• the particle size is of great influence when determining the q / m value, which is why strict attention was paid to uniform particle size distribution [4-25 ⁇ m] in the toner or powder coating samples obtained by screening.
• 2,2'-DTDB monotetramethylammonium salt of 2,2'-dithiobenzoic acid
• the desired particle fraction was activated with a carrier made of magnetite particles of size 50 to 200 ⁇ m of the type “90 ⁇ m Xerographic Carrier” from Plasma Materials Inc., coated with a styrene-methacrylic copolymer 90:10.
• the measurement is carried out on a conventional q / m measuring stand (cf. JH Dessauer, HE Clark “Xerography and related Processes", Focal Press, NY 1965, page 289); by Using a sieve with a mesh size of 25 ⁇ m (508 mesh per inch), from Gebrüder Kufferath, Düren, it was ensured that no carrier could be entrained when the toner was blown out.
• the measurements were carried out at room temperature and 50% relative air humidity; different test conditions are noted in the relevant examples.
• the following q / m values [ ⁇ C / g) were measured as a function of the activation time:
• Example 2 The procedure is as in Example 1, with the difference that 72.9 g of a 25% strength aqueous tetramethylammonium hydroxide solution (0.20 mol) are added.
• Example 2 The procedure is as in Example 1, with the difference that 36.8 g of a 40% strength aqueous tetraethylammonium hydroxide solution (0.10 mol) are used instead of tetramethylammonium hydroxide solution.
• Example 2 The procedure is as in Example 1, with the difference that 73.6 g of a 40% strength aqueous tetraethylammonium hydroxide solution (0.20 mol) are used instead of tetramethylammonium hydroxide solution.
• Example 2 The procedure is as in Example 1, with the difference that 101.7 g of a 20% strength aqueous tetrapropylammonium hydroxide solution (0.10 mol) are used instead of tetramethylammonium hydroxide solution.
• Example 2 The procedure is as in Example 1, with the difference that 65 g of a 40% strength aqueous tetrabutylammonium hydroxide solution (0.10 mol) are used instead of tetramethylammonium hydroxide solution.
• reaction solution After concentration in the circulating air cabinet, the reaction solution is dried at 120.degree. Then it is ground.
• Example 2 The procedure is as in Example 1, with the difference that instead of tetramethylammonium hydroxide solution, 130 g of a 40% strength aqueous tetrabutylammonium hydroxide solution (0.20 mol) be used.
• Example 2 The procedure is as in Example 1, with the difference that 54.4 g of a 40% strength aqueous tributylmethylammonium hydroxide solution (0.10 mol) are used instead of tetramethylammonium hydroxide solution.
• Example 2 The procedure is as in Example 1, with the difference that 47.7 g of a 35% strength methanolic benzyltrimethylammonium hydroxide solution (0.10 mol) are used instead of tetramethylammonium hydroxide solution.
• Example 1 We will proceed in Example 1 with the difference that 30.6 g of 4,4'-sulfonyldibenzoic acid (0.10 mol) instead of 2,2'-dithiodibenzoic acid and 65 g of a 40% aqueous tetrabutylammonium hydroxide solution (0 , 10 mol) can be used.
• Dialec S 309 toner binder described in Example i 100 parts were, without further additives, as described in Example 1, 30 min. kneaded in a kneader, and then ground, classified and measured on a q / m measuring stand.
• Example 7 Monotetrabutylammoniumsalzes the 2,2'-DTDB was incorporated together with 30 parts of Tiona RCL 628 (TiO2 from SCM, England), as described in Example 1, in 69 parts of Crylcoat 430 (carboxyl-containing polyester resin from UCB, Belgium). The following q / m values were measured as a function of the activation time:
• Example 7 A part of the monotetrabutylammonium salt of 2,2'-DTDB listed in Example 7 was, as described in Example 1, incorporated into 99 parts of 430 Crylcoat. The following q / m values were measured as a function of the activation time:
• polyester resin Crylcoat 430 100 parts were kneaded, ground, classified and then measured without any further additive, as described in Example 1.
• Example 5 A part of the monotetrapropylammonium salt of 2,2'-DTDB listed in Example 5 was, as described in Example 1, incorporated into 99 parts of Atlac T 500 (polyester resin based on bisphenol A fumarate, Atlas Chemicals, Belgium). The following q / m values were measured as a function of the activation time:
• Example 5 0.5 part of the monotetrapropylammonium salt of 2,2'-DTDB used in Example 5 was homogeneously incorporated into 99.5 parts of a powder coating binder ( R Alftalat AN 757 from Hoechst AG, polyester resin) analogously to that described in Example 1.
• a powder coating binder R Alftalat AN 757 from Hoechst AG, polyester resin

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Developing Agents For Electrophotography (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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• 1990
  • 1990-10-06 DE DE4031705A patent/DE4031705A1/de not_active Withdrawn
• 1991
  • 1991-10-01 JP JP3515476A patent/JP2687984B2/ja not_active Expired - Lifetime
  • 1991-10-01 EP EP91917235A patent/EP0551336B1/de not_active Expired - Lifetime
  • 1991-10-01 KR KR1019930701043A patent/KR0121884B1/ko not_active IP Right Cessation
  • 1991-10-01 WO PCT/EP1991/001873 patent/WO1992006414A1/de active IP Right Grant
  • 1991-10-01 DE DE59106558T patent/DE59106558D1/de not_active Expired - Lifetime
  • 1991-10-01 US US08/039,021 patent/US5378571A/en not_active Expired - Lifetime
  • 1991-10-01 CA CA002093418A patent/CA2093418C/en not_active Expired - Lifetime

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