EP0628884B1 - Electrostatic toner, comprising a polyamine as charge control agent - Google Patents

Description

The present invention relates to new electrostatic toners containing a polymeric binder and a polyamine as charge stabilizer, the average molecular weight of which is 150 to 15,000 and which has at least 3 nitrogen atoms, the nitrogen atoms being separated from one another by C ₂ -C ₄ -alkylene and having C ₁ -C ₁₃ alkyl, which is optionally substituted by phenyl, hydroxy or carboxyl, phenyl, C ₁ -C ₁₀ alkanoyl, benzoyl, C ₁ -C ₆ alkylcarbamoyl, phenylcarbamoyl or a radical of the formula CO-L-CO, where L is C ₂ -C ₈ -alkylene, where in the latter case a crosslinking of two polyamine units results, and the use of the above-mentioned polyamines as charge stabilizers in electrostatic toners.

Latent electrostatic image recordings are developed that the toner is inductive on the electrostatic image is deposited. The charge stabilizers stabilize the electrostatic charge of the toner. This makes the picture more vivid and sharper contours.

• Fähigkeit zur Entwicklung des latenten elektrostatischen Bildes zu einem farbstarken sichtbaren Bild.
• Leichte Verteilbarkeit in der Tonerzubereitung, um ein störungsfreies, konturenscharfes, gleichförmiges Bild zu erzeugen.
• Unempfindlichkeit gegen Feuchtigkeit.
• Hohe Thermostabilität.

The charge stabilizers used must meet a wide range of requirements:

• Ability to develop the latent electrostatic image into a highly visible color image.
• Easily distributable in the toner preparation in order to produce a trouble-free, contour-sharp, uniform image.
• Insensitivity to moisture.
• High thermal stability.

From EP-A-242 420 electrostatic toners are known which are known as Charge stabilizers contain amines or ammonium salts.

EP-A-163 528 and JP-A-279 258/1989 describe electrostatic Toner with polyamines as charge stabilizers.

However, it has been shown that the charge stabilizers of State of the art often deficiencies in their requirement profile exhibit.

The object of the present invention was therefore to develop new electrostatic Provide toners that have charge stabilizers have the advantageous application properties exhibit.

Accordingly, the electrostatic specified in the beginning Toner found.

All alkyl and alkylene residues occurring in the polyamines can be straight or branched.

Suitable alkyl radicals are e.g. Methyl, ethyl, propyl, isopropyl, Butyl, isobutyl, sec-butyl, pentyl, isopentyl, neopentyl, tert-pentyl, Hexyl, 2-methylpentyl, heptyl, 2-methylhexyl, octyl, Isooctyl, 2-ethylhexyl, nonyl, isononyl, decyl, isodecyl, undecyl, Dodecyl, tridecyl, isotridecyl, benzyl, 1- or 2-phenylethyl, 2-hydroxyethyl, 2- or 3-hydroxypropyl, 1-carboxylethyl or 2-carboxylpropyl. (The terms isooctyl, isononyl, Isodecyl and isotridecyl originate from those after oxosynthesis alcohols obtained - cf. also Ullmann's Encyclopedia der technical chemistry, 4th edition, volume 7, pages 215 to 217, and volume 11, pages 435 and 436).

Suitable alkylene radicals are (CH ₂ ) ₂ , (CH ₂ ) ₃ , (CH ₂ ) ₄ , CH (CH ₃ ) CH ₂ , CH (CH ₃ ) CH (CH ₃ ), CH (C ₆ H ₅ ) CH ₂ or CH (C ₆ H ₅ ) CH (C ₆ H ₅ ).

Suitable alkanoyl residues are e.g. Formyl, acetyl, propionyl, Butyryl, isobutyryl, pentanoyl, isopentanoyl, hexanoyl, heptanoyl, Octanoyl, 2-ethylhexanoyl, nonanoyl or decanoyl.

Suitable alkyl carbamoyl residues are e.g. Methylcarbamoyl, ethylcarbamoyl, Propylcarbamoyl, isopropylcarbamoyl, butylcarbamoyl, Isobutylcarbamoyl, pentylcarbamoyl, isopentylcarbamoyl, neopentylcarbmaoyl or hexylcarbamoyl.

Electrostatic toners containing a polyamine are preferred. whose average molecular weight is 400 to 4,000.

In the electrostatic toners containing a polyamine that has at least 3 nitrogen atoms, the polyamines in generally different proportions of primary, secondary and tertiary nitrogen atoms.

Electrostatic toners which contain a polyamine in which the nitrogen atoms have C ₁ -C ₁₃ -alkyl as substituents are further preferred.

Electrostatic toners containing a polyamine are particularly preferred contain, in which the nitrogen atoms by ethylene or 1,2- or 1,3-propylene, especially ethylene, separated from each other are.

Electrostatic toners which contain a polyamine in which the nitrogen atoms have C ₁ -C ₆ -alkyl as substituents are also particularly preferred.

The polyamines mentioned above are generally known per se or can according to methods known per se, as in the US-A-3 705 200, DE-A-2 253 594 or DE-A-2 606 823, be preserved.

They can be obtained, for example, by using polyamine bases reacted with alkylating or acylating substances, which are the primary and secondary nitrogen atoms of the main body substitute higher. Come as alkylating substances all substances that are associated with the NH groups of Base body under exchange and enter into a reaction for this a substitutable group, e.g. Sulfate, halogen, hydroxy or Acetate. E.g. also consider such substances which contain an activated double bond, such as acrylic acid or styrene, or a reactive group, such as an oxirane ring, exhibit. Also acylating reagents like carboxylic acids, Carboxylic acid esters or isocyanates can be used for this purpose, since they also contain the primary and secondary nitrogen atoms of the Base body can substitute higher.

Those reagents which are themselves substituted are particularly preferred Contain nitrogen atoms and easily with the nitrogen atoms of the base body can react and the largest Part of the primary and secondary amine functions in the main body in Convert tertiary amine functions. Particularly worth mentioning are Dialkylhydroxyalkylamines, whose alkyl groups have 1 to 13 carbon atoms contain linear, branched or cyclic with each other can be connected. They react with the polyamine body with leakage of water.

The corresponding polyamine base bodies can e.g. on itself known way by conventional condensation, addition or substitution reactions from ammonia or amines and the like Reactants, for example by reacting ammonia with ethylene dichloride or propylene dichloride. You can also be produced by partial acylation of the nitrogen atoms with appropriate carboxylic acids. Especially as a basic body those base bodies are preferred which e.g. through polymerization can be obtained from aziridine.

The proportion of the polyamines specified above in the electrostatic Toner is usually 0.01 to 10 wt .-%, based on the weight of the toner.

The polymers contained in the new electrostatic toners Binders are known per se. They are usually thermoplastic and have a softening point of 40 to 200 ° C, preferably 50 to 130 ° C and especially 65 to 115 ° C. Examples for polymeric binders are polystyrene, copolymers of styrene with an acrylate or methacrylate, copolymers of styrene with Butadiene and / or acrylonitrile, polyacrylates, polymethacrylates, Copolymers of an acrylate or methacrylate with vinyl chloride or Vinyl acetate, polyvinyl chloride, copolymers of vinyl chloride with Vinylidene chloride, copolymers of vinyl chloride with vinyl acetate, Polyester resins, epoxy resins, polyamides or polyurethanes.

In addition to the above polyamines and polymers The toners according to the invention can be binders in known Amounts of colorant, magnetically attractable material, waxes and Contain plasticizers.

The colorants can be organic dyes or pigments, such as Nigrosine, aniline blue, 2,9-dimethylquinacridone, C.I. Disperse Red 15 (C.I. 6010), C.I. Solvent Red 19 (C.I. 26 050), C.I. pigment Blue 15 (C.I. 74 160), C.I. Pigment Blue 22 (C.I. 69 810) or C.I. Solvent Yellow 16 (C.I. 12 700) or inorganic pigments, such as carbon black, red lead, yellow lead oxide or chrome yellow. Generally the amount of colorant present in the toner exceeds not 15% by weight based on the weight of the toner.

The magnetically attractable material can be, for example, iron, nickel, chromium oxide, iron oxide or a ferrite of the formula MeFe ₂ O ₄ , in which Me is a divalent metal, for example iron, cobalt, zinc, nickel or manganese.

The toners according to the invention are produced by customary methods Methods, e.g. by mixing the ingredients in a kneader and then pulverizing or melting the polymer Binder or a mixture of the polymeric binders, subsequent fine division of one or more of the polyamines specified above, and the other additives, if used, in the molten resin using the Mixing and kneading machines known for this purpose, subsequent Cooling of the melt to a solid mass and finally Grinding the solid mass to particles of the desired particle size (usually 0.1 to 50 µm). It is also possible that polymeric binder and the charge stabilizer in one Suspend solvent and the other additives in to give the suspension. The suspension can be used as a liquid toner be used.

However, the liquid can also be prepared in a manner known per se spray dry, evaporate the solvents or the liquid freeze dry and the solid residue into particles of grind the desired particle size.

It is also possible to use the charge stabilizers Not to dissolve polyamines, but fine in the solution of the disperse polymeric binder. The toner preparation thus obtained can then, for example according to US-A-4,265,990, in a xerographic imaging system.

The polyamines described in more detail above are advantageous charge stabilizers. As a rule, they meet the requirements initially stated Application profile and are particularly characterized in that they when added to a toner preparation, this is a favorable electrostatic Give a charging profile, i.e. leave the toner charge yourself quickly and highly. Those to be used according to the invention Charge stabilizers also cause the charge to is kept constant at a high level.

The following examples are intended to explain the invention in more detail.

A) Preparation of the polyamines Example H1

277.3 g (1.6 mol) of N, N-dibutyl-N- (2-hydroxyethyl) amine were added Room temperature with 69.6 g (1.28 mol) of polyethylene amine (medium Molecular weight: 430) with the addition of 5 g of 50 wt .-% aqueous hypophosphorous acid mixed. With stirring and nitrogen atmosphere the mixture was heated to 230 ° C. Here distilled a total of 26.9 g of water and 15.1 g of N, N-dibutyl-N- (2-hydroxyethyl) amine from. The residue (a viscous oil) was incorporated into the toner after cooling.

Examples H2 to H6 listed in Table 1 below were carried out analogously to Example H1. N, N-Dibutyl-N- (2-hydroxyethyl) amine was used as the amine. E.g. Polyethylene amine No. Molecular weight Amount [g] Amine amount [g] Distilled water amount [g] Discharge quantity [g] H2 860 94.5 260 18.5 314 H3 860 113.4 234 16.7 308 H4 1500 96.6 260 21.2 313 H5 1500 82.4 277.3 23.5 308 H6 430 69.6 277.3 24.4 303

B) application

The application examples were made with colorant-free toner models, consisting of resin and the charge stabilizers according to the invention, carried out.

I. Production of the toners Example A1

In a solution of 10 g of an uncrosslinked styrene / butyl acrylate resin 0.2 g of the were in 100 ml of xylene at room temperature Polyamine from Example H 1 entered and then freeze-dried.

Example A2

10 g of a non-crosslinked styrene / butyl acrylate resin were placed in a mixer and 0.2 g of the polyamine from Example H 1 intensive mixed, kneaded at 120 ° C, extruded and ground. There were by sighting toner particles with an average particle size of 50 µm generated.

II. Development of the developer and testing

99% by weight of a steel carrier, which had an average particle size of 100 microns with 1% by weight of the toner weighed in exactly and more closely below activated for a certain period of time on a roller block. After that the electrostatic charge of the developer was determined. About 5 g of the activated developer were in a commercially available q / m meter (Epping GmbH, Neufahrn) in a hard-blow-off cell, that was electrically connected to an electrometer, filled. The mesh sizes of those used in the measuring cell Sieves were 80 µm.

This ensured that the toner was blown out as completely as possible, but the carrier remained in the measuring cell. The toner was almost completely removed from the carrier particles by means of a strong air flow (approx. 4,000 cm ³ / min) and simultaneous suction, the latter remaining in the measuring cell. The charge on the carrier was registered on the electrometer. It corresponded to the amount of charging of the toner particles, but with the opposite sign. The amount of q with the opposite sign was therefore used to calculate the q / m value. The mass of blown-off toner was determined by weighing the measuring cell back and the electrostatic charge q / m was calculated therefrom.

The charge determined on the toners is summarized in Table 2 below. Example No. Connection from example Preparation of the toner Charging after activation of 10 min 30 min 60 min 120 min [µC / g] A1 H1 G 9.5 8.8 7.9 7.3 A2 H1 K 6.6 6.9 6.9 6.1 A3 H2 G 5.3 5.5 4.8 4.8 A4 H3 G 6.7 6.4 5.5 5.2 A5 H4 G 6.6 6.4 6.1 5.8 A6 H5 G 7.3 6.8 7.2 7.0 A7 H5 K 4.8 5.1 4.8 3.1 A8 H6 G 6.1 6.5 6.6 6.8

Claims (4)

1. Electrostatic toners comprising a polymeric binder and a charge stabilizer that is a polyamine whose average molecular weight is from 150 to 15,000 and which has at least three nitrogen atoms, wherein the nitrogen atoms are separated from each other by C₂-C₄-alkylene, and are substituted by C₁-C₁₃-alkyl, which may be phenyl-, hydroxyl- or carboxyl-substituted, phenyl, C₁-C₁₀-alkanoyl, benzoyl, C₁-C₆-alkylcarbamoyl, phenylcarbamoyl or a radical of the formula CO-L-CO, where L is C₂-C₈-alkylene, the last case resulting in the crosslinking of two polyamine units.
2. Electrostatic toners as claimed in claim 1 comprising a polyamine whose average molecular weight is from 400 to 4,000.
3. Electrostatic toners as claimed in claim 1 comprising a polyamine in which the nitrogen atoms are substituted by C₁-C₁₃-alkyl.
4. The use of the amines of claim 1 as charge stabilizers in electrostatic toners.