DE19729834A1 - Toner for electrophotography - Google Patents

Description

In formulations for the production of toners for use in the Electrophotography uses a variety of waxes as an anti-offset agent.

Waxes from thermal degradation of polypropylene plastic are hard waxes with a narrow molecular weight distribution. However, the type of manufacture results partially discolored products with unsaturated end groups.

The use of a syndiotactic polypropylene wax to make one Toner is described in EP-A-563 834. These waxes have the disadvantage of one low crystallinity and hardness, which the use as a component for Difficult to make a toner.

The use of narrowly distributed low molecular weight polyolefins manufactured under Use of metallocene catalysts with a polydispersity less than 2 for Production of toners has been proposed in PCT / JP96 / 02134. A disadvantage of materials made with metallocenes is that they are insufficient Temperature stability of the wax melts when entering air.

One way to avoid discoloration of wax melts is Additization of the wax with an antioxidant. However, this is disadvantageous associated costs and partially different discoloration of the melts.

Another possibility is the extreme cleaning of the waxes to remove all residues originating from the polymerization process. This is often done Cleaning via a solution and filtration process or via a Fine distillation.  

All of the methods mentioned cause a considerable amount of production effort of temperature-stable waxes.

The task was therefore to provide easily accessible, temperature-stable waxes to find which for use as a component in toners in improved Are usable.

It was found that waxes from the polymerization of propene together with Comonomers using metallocenes catalysts in additional Use of hydrogen significantly improved temperature stability have, which for the use of these polypropylenes for the production of Toners is beneficial.

The invention thus relates to the use of polypropylene Homopolymer and copolymer waxes, which are less than 10% unsaturated Have chain ends and a melt viscosity of 10 to 100000 mPas measured at 170 ° C, made by polymerization using of metallocene compounds in the presence of hydrogen, as a component for the production of toners.

Such PP waxes are therefore used in a special way for the Use as a component in black and color toners in photocopiers and Laser printers.

In all applications there is discoloration or crosslinking of the melt avoided, which means for the user even at high temperatures and long Waiting times in processing machines no change in the wax melt he follows.

Another advantage of using such polypropylene waxes is that Avoidance of gel-like cross-links, which in the further application Inhomogeneities in the toner result.  

Preferred are polyolefin waxes produced by using sandwich chelate compounds, in particular those produced by using metallocene compounds, characterized in that the metallocene is a compound of the formula I.

This formula also includes compounds of the formula Ia

and the formula Ib

In formulas I, Ia and Ib, M ^{1 is} a metal from group IVb, Vb or VIb of the periodic table, for example titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, preferably titanium, zirconium and hafnium.

R ¹ and R ² are the same or different and represent a hydrogen atom, a C ₁ -C ₁₀ , preferably C ₁ -C ₃ alkyl group, in particular methyl, a C ₁ -C ₁₀ , preferably C ₁ -C ₃ alkoxy group , a C ₆ -C ₁₀ -, preferably C ₆ -C ₈ aryl group, a C ₆ -C ₁₀ -, preferably C ₆ -C ₈ aryloxy group, a C ₂ -C ₁₀ -, preferably C ₂ - C ₄ - Alkenyl group, a C ₇ -C ₄₀ , preferably C ₇ -C ₁₀ arylalkyl group, a C ₇ -C ₄₀ , preferably C ₇ -C ₁₂ alkylaryl group, a C ₈ -C ₄₀ , preferably C ₈ -C ₁₂ Arylalkenyl group or a halogen atom, preferably chlorine.

R ³ and R ⁴ are the same or different and mean a mono- or polynuclear hydrocarbon radical which can form a sandwich structure with the central atom M ¹ . R ³ and R ⁴ are preferred cyclopentadienyl, indenyl, benzoindenyl or fluorenyl, it being possible for the base members to carry additional substituents or to be bridged to one another. In addition, one of the radicals R ³ and R ^{4 can be} a substituted nitrogen atom, where R ^{24 has} the meaning of R ¹⁷ and is preferably methyl, t-butyl or cyclohexyl.

R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are identical or different and represent a hydrogen atom, a halogen atom, preferably a fluorine, chlorine or bromine atom, a C ₁ -C ₁₀ -, preferably C ₁ -C ₄ alkyl group, a C ₆ -C ₁₀ -, preferably C ₆ -C ₈ aryl group, a C ₁ -C ₁₀ -, preferably C ₁ -C ₃ alkoxy group, a -NR ¹⁶ ₂ -, -SR ¹⁶ -, -OSiR ¹⁶ ₃ -, -SiR ¹⁶ ₃ - or -PR ¹⁶ ₂ radical, wherein R ^{16 is} a C ₁ -C ₁₀ , preferably C ₁ -C ₃ alkyl group or a C ₆ -C ₁₀ , preferably C ₆ -C ₈ aryl group, or in the case of Si or P containing radicals is also a halogen atom, preferably chlorine atom, or two adjacent radicals R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ or R ¹⁰ form with the they connect C atoms to form a ring. Particularly preferred ligands are the substituted compounds of the basic bodies indenyl, benzoindenyl, fluorenyl and cyclopentadienyl.

R ¹³ is

= BR ¹⁷ , = AlR ¹⁷ , -Ge-, -Sn-, -O-, -S-, = SO, = SO ₂ , = NR ¹⁵ , = CO, = PR ¹⁵ or = P (O) R ¹⁵ , wherein R ¹⁷ , R ¹⁸ and R ^{19 are} identical or different and a hydrogen atom, a halogen atom, a C ₁ -C ₃₀ , preferably C ₁ -C ₄ alkyl group, in particular methyl group, a C ₁ -C ₁₀ fluoroalkyl group, preferably CF ₃ group, a C ₆ -C ₁₀ fluoroaryl group, preferably pentafluorophenyl group, a C ₆ -C ₁₀ , preferably C ₆ -C ₈ aryl group, a C ₁ -C ₁₀ , preferably C ₁ -C ₄ alkoxy group, in particular methoxy group, a C ₂ -C ₁₀ -, preferably C ₂ -C ₄ - alkenyl group, a C ₇ -C ₄₀ -, preferably C ₇ -C ₁₀ arylalkyl group, a C ₈ -C ₄₀ -, preferably C ₈ -C ₁₂ -Arylalkenyl group or a C ₇ -C ₄₀ -, preferably C ₇ -C ₁₂ - alkylaryl group, or R ¹⁷ and R ¹⁸ or R ¹⁷ and R ¹⁹ each form a ring together with the atoms connecting them.

M ² is silicon, germanium or tin, preferably silicon and germanium. R ¹³ is preferably -CR ¹⁷ R ¹⁸ , = SiR ¹⁷ R ¹⁸ , -GeR ¹⁷ R ¹⁸ , -O-, -S-, = SO, = PR ¹⁷ or = P (O) R ¹⁷ .

R ¹¹ and R ¹² are the same or different and have the meaning given for R ¹⁷ . m and n are identical or different and mean zero, 1 or 2, preferably zero or 1, where m plus n is zero, 1 or 2, preferably zero or 1.

R ¹⁴ and R ¹⁵ have the meaning of R ¹⁷ and R ¹⁸ .

Examples of suitable metallocenes are the rac isomers of:

Dimethylsilyl-bis-1- (2,3,5-trimethylcyclopentadienyl) zirconium dichloride,
Dimethylsilyl-bis-1- (2,4-dimethyl-cyclopentadienyl) zirconium dichloride,
Dimethylsilyl-bis-1- (2-methyl-4,5-benzoindenyl) zirconium dichloride,
Dimethylsilyl-bis-1- (2-methyl-4-ethylindenyl) zirconium dichloride,
Dimethylsilyl-bis-1- (2-methyl-4-i-propylindenyl) zirconium dichloride,
Dimethylsilyl-bis-1- (2-methyl-4-phenylindenyl) zirconium dichloride,
Dimethylsilyl-bis-1- (2-methyl-indenyl) zirconium dichloride,
Dimethylsilyl-bis-1- (2-methyltetrahydroindenyl) zirconium dichloride,
Dimethylsilyl-bis-1-indenylzirconium dichloride,
Dimethylsilyl-bis-1-indenylzirconiumdimethyl,
Dimethylsilyl-bis-1-tetrahydroindenylzirconium dichloride,
Diphenylmethylene-9-fluorenylcyclopentadienylzirconium dichloride,
Diphenylsilyl-bis-1-indenylzirconium dichloride,
Ethylene bis (1- (2-methyl-4,5-benzoindenyl) zirconium dichloride,
Ethylene bis-1 (2-methyl-4-phenylindenyl) zirconium dichloride,
Ethylene-bis-1- (4,7-dimethyl-indenyl) zirconium dichloride,
Ethylene bis-1-indenyl zirconium dichloride
Ethylene bis-1-tetrahydroindenyl zirconium dichloride,
Ethylene-bis-1- (2-methyl-tetrahydroindenyl) zirconium dichloride,
Ethylene-bis-1- (2-methyl-4,5-benzo-6,7-dihydroindenyl) zirconium dichloride,
Ethylene-bis-1- (2-methyl-indenyl) zirconium dichloride,
as well as the alkyl or aryl derivatives of these metallocene dichlorides.

Suitable cocatalysts are used to activate the single-center catalyst systems. Suitable cocatalysts for metallocenes of the formula I are organoaluminum compounds, in particular alumoxanes or aluminum-free systems such as R ²² _x NH _4-x BR ²³ ₄ , R ²² _x PH _4-x BR ²³ ₄ , R ²² ₃ CBR ²³ ₄ or BR ²³ ₃ . In these formulas, x is a number from 1 to 4, the radicals R ²² are the same or different, preferably the same, and are C ₁ -C ₁₀ alkyl or C ₆ -C ₁₈ aryl or two radicals R ²² form together with the they connect an atom to a ring, and the radicals R ²³ are identical or different, preferably identical, and represent C ₆ -C ₁₈ aryl, which can be substituted by alkyl, haloalkyl or fluorine. In particular, R ^{22 represents} ethyl, propyl, butyl or phenyl and R ^{23 represents} phenyl, pentafluorophenyl, 3,5-bis-trifluoromethylphenyl, mesityl, xylyl or tolyl.

These cocatalysts are particularly suitable in combination with metallocenes of the formula I when R ¹ and R ^{2 are} a C ₁ -C ₁₀ alkyl group or an aryl or benzyl group, preferably methyl group. The derivatization to the metallocenes of the formula I can be carried out by methods known from the literature, for example by reaction with alkylating agents such as methyl lithium (cf. Organometallics 9 (1990) 1539; J. Am. Chem. Soc. 95 (1973) 6263).

In addition, a third component is often required to protect against to maintain polar catalyst poisons. For this purpose are organoaluminum Connections such as B. triethyl aluminum, tributyl aluminum and others as well Mixtures of these are suitable.

Depending on the process, supported single-center catalysts can also be used Use come. Catalyst systems are preferred in which a high polymerization activity, the residual contents of the carrier material and cocatalyst do not exceed a concentration of 100 ppm in the product.

To prepare the waxes according to the invention, propene is present in the presence of Hydrogen and optionally further olefins with 2 to 18 carbon atoms as comonomers polymerized. Examples of comonomers which can be used are ethylene, 1-butene, 1- Pentene, 1-hexene, 1-octene, 2-methyl-1-propene, 3-methyl-1-butene, 3-methyl-1- pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, styrene. The is preferred Polymerization of propylene and the copolymerization of propylene with a 1- Olefin of 2 to 10 carbon atoms. Examples of copolymer waxes are Propylene / ethylene, propylene / 1-butene and propylene / 1-hexene waxes.

Copolymer waxes contain 0 to 20 wt .-% of the comonomer based on the  Total polymer. Terpolymer waxes contain at least 80% by weight of the Main polymer, the two comonomers each up to 19 wt .-%, in Sum of both comonomers, however, a maximum of 20% by weight of the total polymer are included.

The waxes according to the invention contain less than 10% unsaturated End groups, preferably less than 5% unsaturated end groups.

The waxes of the invention can be in any suitable type of reactor be produced, such as a loop reactor, autoclave or gas phase. The regulation the molecular weight is preferably not by varying the Polymerization temperature, but at constant temperature through change of hydrogen pressure.

The polypropylene homo- and copolymer waxes have a viscosity of 10 to 100,000 mPas at 170 ° C, the molecular weight distribution is narrow and is M _w / M _n <5, preferably less than 3.

Examples

The following abbreviations are used in the following examples:

DSC = Differential Scanning Calorimetry
GPC = gel permeation chromatography
GC = gas chromatography
Mw = weight average molar mass in g / mol according to GPC
Mn = number average molar mass in g / mol according to GPC
Mw / Mn = polydispersity.

Melting points (Smp) and heats of fusion (ΔH) were determined by DSC measurements with a "Perkin-Elmer DSC 7" at 10 ° C / min heating and cooling rate from the 2nd  Heating determined.

The melt viscosities (SV) are at 170 ° C with a rotary viscometer been determined.

The isotactic index (I.I.) is determined by IR spectroscopy J.P. Luongo, J. Appl. Polym. Chem., 3, 302 (1960).

The chain ends of the polymers are examined by means of ¹³ C-NMR as described in Polymer, 1989, Vol. 30, p. 428. If less than 10% of all end groups are present as isopropenyl end groups, the indication "saturated" is found in Table 1.

example 1

30 kg of propene, 12 mmol of triisobutylaluminum were placed in an inert 100 dm ³ reactor, heated to 70 ° C. with stirring and 1.0 bar of hydrogen were metered in.

At the same time, 31 mg of ethylene bis-1,1 '- (tetrahydroindenyl) zirconium dichloride are dissolved in 15 ml of a 10% by weight toluene solution of methylaluminoxane and stirred. The polymerization is started by adding the catalyst solution in portions and the internal temperature of the reactor is regulated at 70.degree. Hydrogen was metered in according to GC control and kept constant at the initial value. After 1 hour the polymerization was stopped by adding CO ₂ , the reactor was depressurized and the product was discharged as a melt. The result is 12.1 kg of PP wax. The GPC measurement shows an M _w of 3528 and Mw / Mn equal to 2.1. The properties are summarized in Table 1.

Comparative Example 1

Example 1 was repeated, but no hydrogen was metered in. The properties are summarized in Table 1. The GPC measurement gives an M _w of 12640 and M _w / M _n equal to 2.5.

Example 2

Example 1 was carried out with 26 mg of dimethylsilylbisindenyl zirconium dichloride, 230 mbar of hydrogen being used. The result is 9.9 kg of PP wax. The GPC measurement gives an M _w of 6920 and M _w / M _n equal to 2.9. The properties are summarized in Table 1.

Comparative Example 2

Example 1 was repeated, but instead of hydrogen, 200 mmol of trimethylaluminum were metered in as a solution in toluene. The properties are summarized in Table 1. The GPC measurement gives an M _w of 24300 and M _w / M _n equal to 2.8.

Example 3

The waxes from the previous examples were added in the drying cabinet Annealed at 200 ° C for 4 h with air. After the samples had cooled, the Discoloration is carried out using a set of comparison samples (grade 1: colorless, grade 6: dark brown). The results of the tempering tests (Table 1) show that waxes produced in the presence of hydrogen are improved Have thermal stability.

Table 1

Claims (2)

1. use of polypropylene homopolymer and copolymer waxes, which have less than 10% unsaturated chain ends and one Have a melt viscosity of 10 to 100,000 mPas measured at 170 ° C, made by polymerization using metallocene Compounds in the presence of hydrogen, as a component for the Production of toners. 2. Use according to claim 1, characterized in that it is the metallocene compounds around sandwich chelate compounds with titanium, Zircon or hafnium acts as a metal atom.