EP1318433A2 - Use of polyolefinic waxes in electrophotographic toners - Google Patents

Abstract

Polar modified polyolefin waxes (I), produced using metallocene catalysts, are used in phototoners. <??>An Independent claim is also included for phototoners containing pigment component(s), resin component(s) and (I).

Description

The present invention relates to the use of means Metallocene catalysts produced polar modified polyolefin waxes in Photo toners as well as photo toners, such polar modified polyolefin waxes contain.

So-called photo toners are usually used in modern copying processes used from resins, pigments, charge control agents and waxes as well where appropriate, flow aids exist. The powdery photo toners form the Copying the template to be copied usually first on a Transfer roller, are transferred from there to the copy paper and then thermally fixed.

The waxes contained in the toner as a recipe component favor and anti-offset agents, the detachment of the photo toner from the fixing roller, act as Adhesion promoter in the transfer to paper and contribute in the manufacture of the Toner as a dispersion aid for the homogeneous distribution of the pigments.

Modern copiers can process more than 40 copies / min according to a conveying speed of more than 0.2 m / s.

The need for copiers that work ever faster is correspondingly quick attractive toner systems and places high demands on the Individual components of the toner formulation.

US-A-5,707,772 describes the use of an anti-offset agent based on with Metallocene catalysts described non-polar polyolefins described.

EP-0 843 222 A1 describes the use of release agents based on non-polar olefin homo- and copolymer waxes, which are also produced using Metallocene catalysts were produced.

EP-0 890 882 A1 describes the use of non-polar, by means of metallocenes produced propylene homo- and copolymer waxes in photo toners.

The waxes mentioned are the requirements of modern, fast-running Make copying machines, not fair in all aspects. In particular there is Need for wax components with improved anti-offset effect, improved Effect on the adhesion of the print on the paper as well as further optimized pigment dispersing properties.

Oxidized waxes are also known (DE-A-196 17 230), obtainable from Metallocene catalysis produced polyolefins.

DE-A-198 10 890 describes the polar modification of Metallocene catalysts produced polyethylene waxes by oxidation with Oxygen or gases containing oxygen are described in the melt.

DE-A-10 13 672 is the production of polar modified waxes Oxidation of high molecular weight, made with metallocene catalysts Polyethylene described.

DE-A-196 48 895 discloses polar modified polypropylene waxes, made with the help of catalysts of the Ziegler or metallocene type obtained polypropylene waxes. These are used for modification α, β-unsaturated carboxylic acids or their derivatives implemented. As possible It is used in aqueous dispersions, hot melt adhesive formulations and called plastic additives.

Surprisingly, it has now been found that polar waxes, their non-polar precursors were produced with the help of metallocene catalysts, in are particularly advantageously suitable as additives for photo toners. In particular with such waxes a more homogeneous dispersion of the pigment in the Production of the toner and an improved anti-offset effect during the fixing process and increases the adhesion of the print to the paper.

The invention therefore relates to the use of means Metallocene catalysts produced polar modified polyolefin waxes in Photo toners.

a) durch Oxidation mit Sauerstoff oder sauerstoffhaltigen Gasen und gegebenenfalls Derivatisierung der Oxidate und/oder

b) durch Umsetzung mit α,β-ungesättigten Carbonsäuren, Estern oder Anhydriden und gegebenenfalls Derivatisierung der Umsetzungsprodukte und/oder

c) durch Umsetzung mit Styrol

erfolgt.The invention also relates to the use of polar modified polyolefin waxes in photo toners, the polar modification starting from non-polar polyolefin waxes produced with metallocene catalysts

a) by oxidation with oxygen or oxygen-containing gases and, if appropriate, derivatization of the oxidates and / or

b) by reaction with α, β-unsaturated carboxylic acids, esters or anhydrides and, if appropriate, derivatization of the reaction products and / or

c) by reaction with styrene

he follows.

Homopolymers are preferred as polyolefin waxes for polar modification of linear or branched α-olefins with 2 to 30 carbon atoms or copolymers these olefins used with each other.

The polar modified polyolefin waxes preferably have melt viscosities, measured at 170 ° C, from 5 to 10000 mPa.s, saponification numbers from 0.1 to 100 mg KOH / g and softening points from 80 to 160 ° C.

The invention further relates to photo toners containing at least one Pigment component, a resin component and a by means of metallocene catalyst manufactured polar modified polyolefin wax.

As a basic component, photo toners generally contain resins based on polyesters or styrene-acrylate copolymers. For example, quaternary ammonium salts for a positive charge and aluminum-azo complexes for a negative charge of the toner powder are used as charge control agents which support the transfer of the toner from the photo roller to the paper base.
To support the free-flowing properties, small amounts of highly disperse silicas can be added to the toner powder.

Depending on the desired color, the toners are already in the thermoplastic Mixture of suitable black or color pigments added.

The term "polyolefin waxes" are used below Low molecular weight polymers of linear or metallocene catalysts understood branched α-olefins having 2 to 30 carbon atoms. Locked in are both homopolymers of the olefins mentioned and copolymers of these Olefins among each other in any ratio.

Metallocene catalysts for the production of the polyolefin waxes are chiral or nonchiral transition metal compounds of the formula M ¹ L _x . The transition metal compound M ¹ L _x contains at least one metal central atom M ¹ to which at least one π ligand, for example a cyclopentadienyl ligand, is bonded. In addition, substituents such as halogen, alkyl, alkoxy or aryl groups can be bonded to the metal central atom M ¹ . M ¹ is preferably an element of III., IV., V. or VI. Main group of the periodic table of the elements, such as Ti, Zr or Hf. Cyclopentadienyl ligand is understood to mean unsubstituted cyclopentadienyl radicals and substituted cyclopentadienyl radicals such as methylcyclopentadienyl, indenyl, 2-methylindenyl, 2-methyl-4-phenylindenyl, tetrahydroindenyl or octa-tetra-hydrofluoryl or octa-tetra-hydrofluoryl or octa. The π ligands can be bridged or unbridged, whereby single and multiple bridging - also via ring systems - are possible. The term metallocene also includes compounds with more than one metallocene fragment, so-called multinuclear metallocenes. These can have any substitution pattern and bridging variant. The individual metallocene fragments of such multinuclear metallocenes can be of the same type or different from one another. Examples of such multinuclear metallocenes are described, for example, in EP-0 632 063 A1.

Examples of general structural formulas of metallocenes and their use for the production of olefin homo- and copolymer waxes include in EP-0 571 882 A1.

The polyolefin waxes have melt viscosities before polar modification, measured at 170 ° C, between 5 and 10000 mPa.s and softening points between 85 and 165 ° C.

The polar modification of these polyolefin waxes can be by oxidation with Oxygen or gases containing oxygen below or above the melting point respectively. The wax is preferably in the molten state Temperatures between the melting point of the wax and 200 ° C Introducing oxygen or gases containing oxygen, preferably air, oxidized. The waxes modified by oxidation have acid numbers between 0.1 and 100, preferably 1 and 30 mg KOH / g, melt viscosities, measured at 170 ° C, from 5 to 10,000 mPa.s, preferably 20 to 5000 mPa.s and Softening points from 80 to 160 ° C. Derivatives are also included such oxidates, such as those caused by their esterification with mono- or polyvalent ones aliphatic or aromatic alcohols, e.g. Ethanol, propanols, butanols, Ethanediol, butanediols, glycerin, trimethylolpropane, pentaerythritol or Benzyl alcohol can be produced. Also, in the event that partial esters are present, the further derivatization of such esters, for example, by esterification with Acid components such as acrylic acid or methacrylic acid possible.

Another possibility of polar modification is to implement the Polyolefin wax with α, β-unsaturated carboxylic acids or their derivatives, optionally in the presence of a radical initiator. Examples of α, β-unsaturated Carboxylic acids are acrylic acid, methacrylic acid, crotonic acid and maleic acid. Examples of derivatives of α, β-unsaturated carboxylic acids are their esters or Amides or anhydrides, e.g. Acrylic acid alkyl esters, acrylic acid amides, semi or Diesters of maleic acid, maleic anhydride or amides of maleic acid such as e.g. Maleimide or N-alkyl substituted maleimides. Mixtures of these can also be used Connections are used. Maleic acid and its are preferred Descendants, maleic anhydride is particularly preferred. The α, β-unsaturated Carboxylic acids or their derivatives come in an amount based on the amount used Polyolefin wax, from 0.1-20% by weight, is used. The production of such radically generated polar reaction products is, for example, in EP-0 941 257 A1. By implementing polyolefin waxes with α, β-Unsaturated carboxylic acids and their derivatives obtained polar modified Polyolefin waxes have melt viscosities, measured at 170 ° C, from 5 to 10000 mPa.s, preferably 10 to 5000 mPa.s, saponification numbers from 0.1 to 100 mg KOH / g, preferably 2 to 80 mg KOH / g and softening points from 80 to 160 ° C, preferably 100 to 155 ° C.

According to the invention is also the use of wax products by radical conversion of polyolefin waxes with styrene in an amount of 0.1-30% by weight, based on the polyolefin wax used.

It is also possible to apply the modification methods mentioned combine, for example in such a way that the polyolefin wax is initially mixed with α, β-unsaturated Implemented carboxylic acids or their derivatives and then oxidized.

Examples

The melt viscosities of the wax products described below were: measured according to DIN 51562 with a rotary viscometer. The saponification numbers were in accordance with DIN standard 53401, the softening points and flow hardness (Stamp penetrations) according to the "standard methods" M-IV 2 (75) and M-III 13 (75) of the German Society for Fat Chemistry.

The following polyolefin waxes were prepared for the derivatization based on the examples of the patents EP 321 851 and EP 571 882 using metallocene catalysts: Type Viscosity / 170 ° C mPa.s Erweichungspkt. R / K (° C) Flow hardness bar Polyolefin wax 1 Ethylene homopolymer 50 123 530 Polyolefin wax 2 Propylene homopolymer 30 136 880 Polyolefin wax 3 Propylene homopolymer 2800 140 900

Derivatization through oxidation

In a with thermometer, high-speed propeller stirrer and a dip tube As a gas inlet equipped 2 I four-necked flask was a mixture of 700 g of the polyolefin wax 1 melted. After reaching an internal temperature from 140 ° C the agitator was put into operation at 4000 revolutions / min and an air flow of 200 l / h was introduced into the wax melt. The The reaction temperature rose to a maximum of 165 ° C. At intervals of 2 hours Samples taken to determine viscosity. The reaction was stopped after 6 h completed. The product formed (modified wax 1) showed a saponification number of 30 mg KOH / g, a viscosity of 20 mPa.s at 170 ° C, a softening point (Ring / ball) of 118 ° C and a flow hardness of 380 bar.

Derivatization by reaction with maleic anhydride

500 g of the polyolefin wax 2 were in a with a stirrer, internal thermometer and distillation bridge equipped glass apparatus under nitrogen blanket melted. At a temperature of 165 ° C in the course of 3 h a dosing funnel continuously 26.7 g liquid, heated to approx. 60 ° C Maleic anhydride metered in; at the same time, from a second dropping funnel the continuous addition of 10.5 g of di-tert-butyl peroxide. After the end of A further 1.1 g of di-tert-butyl peroxide were added to the reaction mixture, increased the reaction temperature to 170 ° C and allowed to readjust for 2 h. Subsequently a vacuum of about 30 mbar was applied and the volatile components were distilled off. After about 30 minutes, the pressure was released to atmospheric pressure by introducing nitrogen. Nitrogen was passed through the for a further 15 min to remove volatile residuals Wax melt and poured it out. A light yellow wax was obtained (modified wax 2) with a saponification number of 58 mg KOH / g, one Melt viscosity at 170 ° C of 20 mPa.s, a ring / ball softening point of 134 ° C and a flow hardness of 900 bar.

In the same way, polyolefin wax 3 became polar with maleic anhydride modified. A light yellow wax (modified wax 3) was obtained with a Saponification number of 60 mg KOH / g, a melt viscosity at 170 ° C of 2100 mPa.s, a ring / ball softening point of 138 ° C and a flow hardness of 1000 bar.

In the following examples, the processing of the invention Waxes in toners, such as those used in photocopiers and digital printing machines are shown:

example 1

90 parts by weight of a styrene-acrylate resin (type CPR 100, manufacturer Mitsui; Glass temperature 60 ° C; MFR / 140 ° C 5 g / 10 min) with 4 parts by weight of a Black pigments (carbon black average particle size of 2 µm; manufacturer: Timcal), 1.0 part by weight of a charge control agent (Copy Charge N4S, manufacturer: Clariant GmbH) and 4 parts by weight of the modified wax 1 according to the invention 150 ° C mixed homogeneously in a kneader. This mixture now became one Shredded toner powder with an average particle size of 12 µm (100% <20 µm). the Toner powder was now 0.5 parts by weight of a silica-based Superplasticizer (type HDK, manufacturer: Wacker) added. 5 g of this now pourable Mixture was mixed with 95 g of iron powder and placed in the storage container Copier filled.

With the help of the photomagnetic roller in the copier was now in one Area of 20x100 mm toner powder applied to a paper. This picture was taken then with a roller arrangement consisting of a rigid heatable roller and an elastic cold roller, at 160 ° C and a throughput speed of 150 mm / s fixed. Then another white sheet was passed through the hot one Roll pairing performed and examined for toner residues. On the white sheet no "ghost pictures" recognizable.

Example 2

1 g of the toner powder from Example 1 was stirred with 2 g of ethanol and with a Doctor blade applied to a paper base (layer thickness: 40 µm). To The remaining powder layer was dried at 40 ° C at 140 ° C and 120 mm / s throughput speed fixed. The fixed toner layer was with a test construction abrasion test as used in the testing of printing inks, examined. The friction paper on toner with 50 rubbing movements showed no measurable abrasion. After folding the toner layer by 180 °, none visible fold lines and flaking.

Example 3

Instead of the modified wax 1 mentioned in Example 1, the modified waxes 2 and 3 used. At the same time, the pigment content was around 25% reduced. Otherwise, the procedure was as in Example 1. The prints showed that same color depth as a standard without wax tested in parallel according to Example 1. This shows that the addition of wax makes it more effective Pigment dispersion is achieved.

Claims (5)

Use of polar produced using metallocene catalysts modified polyolefin waxes in photo toners. Use of polar modified polyolefin waxes in photo toners, the polar modification starting from non-polar polyolefin waxes produced with metallocene catalysts a) by oxidation with oxygen or oxygen-containing gases and, if appropriate, derivatization of the oxidates and / or b) by reaction with α, β-unsaturated carboxylic acids, esters or anhydrides and, if appropriate, derivatization of the reaction products and / or c) by reaction with styrene he follows. Use of polyolefin waxes according to claims 1 and 2, wherein as polyolefin waxes for polar modification homopolymers of linear or branched α-olefins with 2 to 30 carbon atoms or copolymers of these olefins can be used with each other. Use according to claims 1 to 3, wherein the polar modified Polyolefin waxes melt viscosities, measured at 170 ° C, from 5 to 10000 mPa.s, saponification numbers from 0.1 to 100 mg KOH / g and Have softening points of 80 to 160 ° C. Photo toner containing at least one pigment component, one Resin component and a polar produced using a metallocene catalyst modified polyolefin wax.