JPH1184718A - Electrophotographic toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily obtain thermally stable waxes having more favorable usefulness as components in a toner. SOLUTION: Polypropylene homopolymer and copolymer waxes prepd. by polymn. using a metallocene compd. in the presence of hydrogen and having <10% unsatd. chain terminals and 10-100,000 mPas melt viscosity measured at 170 deg.C are used as components for producing a toner. These waxes have very satisfactory thermal stability and do not cause the discoloration and crosslinking of a melt of the waxes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for using a polypropylene homopolymer or copolymer wax prepared by using a metallocene compound in the presence of hydrogen as a component in an electrophotographic toner.

[0002]

BACKGROUND OF THE INVENTION Various waxes have been used as anti-offset agents in formulations for producing toners used in electrophotography. The wax obtained from the pyrolysis of polypropylene plastic is a hard wax with a narrow molecular weight distribution. However, this process occasionally gives discolored products with unsaturated end groups.

[0003] The use of syndiotactic polypropylene waxes for toner production is described in EP-A-563 834. These waxes have the disadvantage of low crystallinity and hardness, which makes it more difficult to use them as a component for toner production. A method is proposed in PCT / JP96 / 02134 in which a low molecular weight polyolefin produced with a metallocene catalyst and having a narrow molecular weight distribution, ie a polydispersity of less than 2, is used for the production of toner. A disadvantage of materials made with metallocenes is the poor thermal stability of the wax melt when exposed to air.

One possible way to avoid discoloration of the wax melt is to add an antioxidant to the wax. However, this method is compromised by the disadvantages of the associated costs and other types of discoloration of the melt that sometimes occurs. Another possible method is to thoroughly purify the wax to remove any residual material from the polymerization process. This purification process often involves a solution and filtration process.
process) or by a precise distillation process.

[0005] All of these methods require considerable expense to produce thermally stable waxes.

[0006]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to find a thermally stable wax which can be obtained in a simple manner and has better utility as a component in a toner. It is.

[0007]

SUMMARY OF THE INVENTION Waxes obtained by polymerizing propene together with comonomers using metallocene catalysts and additionally hydrogen are advantageous when these polypropylenes are used for toner production. It has now been found that it has a significantly improved thermal stability.

Therefore, the present invention has been obtained by polymerizing with a metallocene compound in the presence of hydrogen,
Less than 10% unsaturated chain ends and 10-100, measured at 170 ° C.
Provided is a method for using polypropylene homopolymer and copolymer wax having a melt viscosity of 000 mPas as a component for toner production. Therefore, such a
PP waxes are used in particular as components in black and color toners in photocopiers and laser printers.

In all applications, discoloration or cross-linking of the melt is avoided, so that users do not experience wax denaturation, even at high temperatures and long wait times in process equipment. Disappears. A further advantage of the use of such a polypropylene wax is that the generation of crosslinked gel-like material, which leads to inhomogeneity of the toner in later use phases, can be avoided.

[0010] Polyolefin waxes prepared using sandwich-type chelating compounds are preferred, and in particular the following formula I:

[0011]

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Those produced using the metallocene compound represented by the formula (1) are preferred. At this time, the above equation is obtained by the following equation Ia

[0013]

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And the formula Ib

[0015]

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The compound represented by the formula: In the formulas I, Ia and Ib, M ¹ is a group IVb, Vb or VIb of the periodic table
Group metals such as titanium, zirconium, hafnium,
Vanadium, niobium, tantalum, chromium, molybdenum,
Tungsten, preferably titanium, zirconium and hafnium.

R¹And R^TwoAre the same or different,
Hydrogen atom, C₁-C_Ten-Preferably C₁-C_Three-Alkyl group,
Especially methyl, C₁-C_Ten-Preferably C₁-C_Three-Alkoxy
Group, C₆-C_Ten-Preferably C₆-C₈-Aryl group, C₆-C_Ten-
 , Preferably C₆-C₈-Aryloxy group, C_Two-C_Ten-Good
Preferably C_Two-C_Four-Alkenyl group, C₇-C₄₀-Preferably C₇
-C _Ten-Arylalkyl group, C₇-C₄₀-Preferably C₇-C
₁₂-Alkylaryl group, C₈-C₄₀-Preferably C₈-C₁₂
-An arylalkenyl group or a halogen atom, preferably
Is chlorine.

R ³ and R ⁴ are the same or different and are each a monocyclic or polycyclic hydrocarbon residue capable of forming a sandwich structure with the central atom M ¹ . R ³ and R ⁴
Is preferably cyclopentadienyl, indenyl,
Benzindenyl or fluorenyl, wherein
These basic structures may have additional substitutions or may be cross-linked to one another. Furthermore, these groups R ³ and
One of R ⁴ may be a substituted nitrogen atom,
Here, R ²⁴ has the meaning defined for R ¹⁷ and is preferably methyl, t-butyl or cyclohexyl.

R ⁵ , R ⁶ , R ⁸ and R ⁹ are the same or different;
A hydrogen atom, a halogen atom, preferably fluorine,
Chlorine or bromine atom, C ₁ -C _10- , preferably C ₁ -C ₄ -alkyl group, C ₆ -C _10- , preferably C ₆ -C ₈ -aryl group, C ₁ -C
₁₀ -, preferably C ₁ -C ₃ - alkoxy group, -NR ¹⁶ _2, -S
_{^{R 16, -OSiR 16 3, -SiR}} 16 2 or -PR ¹⁶ ₂ group (herein, R
¹⁶ is C ₁ -C _10- , preferably C ₁ -C ₃ -alkyl or C ₆
-C _10- , preferably a C ₆ -C ₈ -aryl group, or
A halogen atom in the case of a Si- or P-containing group, preferably also a chlorine atom) or two adjacent
The R ⁵ , R ⁶ , R ⁸ or R ⁹ groups together with the carbon atoms connecting them form a ring. Particularly preferred ligands are substituted compounds derived from the basic structures of indenyl, benzindenyl, fluorenyl and cyclopentadienyl.

R ¹³ is

[0021]

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= 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 the same or different and each is a hydrogen atom A halogen atom, a C ₁ -C _30- , preferably a C ₁ -C ₄ -alkyl group, especially a methyl group, a C ₁ -C ₁₀ -fluoroalkyl group, preferably a CF ₃ group, a C ₆ -C ₁₀ -fluoroaryl Group, preferably a pentafluorophenyl group,
C ₆ -C _10- , preferably C ₆ -C ₈ -aryl, C ₁ -C _10- , preferably C ₁ -C ₄ -alkoxy, especially methoxy, C ₂ -C ₁₀
-, Preferably C ₂ -C ₄ -alkenyl group, C ₇ -C _40- , preferably C ₇ -C ₁₀ -arylalkyl group, C ₈ -C _40- , preferably C ₈ -C ₁₂ -arylalkenyl group Or C ₇ -C _40- , preferably C ₇ -C ₁₂ -alkylaryl, or R
¹⁷ and R ¹⁸ or R ¹⁷ and R ¹⁹ are each, together with the atoms connecting them form a ring.

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, a = PR ¹⁷ or = P (O) R ^17. R ¹¹ and R ¹² are the same or different and each has the meaning defined for R ¹⁷ . m and n are the same or different;
Or 2, preferably 0 or 1, where m and n
Is 0, 1 or 2, preferably 0 or 1.

R ¹⁴ and R ¹⁵ have the meaning defined for R ¹⁷ and R ¹⁸ . An example of a suitable metallocene is the rac-isomer of the following compound: dimethylsilylbis-1-
(2,3,5-trimethylcyclopentadienyl) zirconium dichloride, dimethylsilylbis-1- (2,4-dimethylcyclopentadienyl) zirconium dichloride,
Dimethylsilylbis-1- (2-methyl-4,5-benzindenyl) zirconium dichloride, dimethylsilylbis
-1- (2-methyl-4-ethylindenyl) zirconium dichloride, dimethylsilylbis-1- (2-methyl-4-i-
Propylindenyl) zirconium dichloride, dimethylsilylbis-1- (2-methyl-4-phenylindenyl) zirconium dichloride, dimethylsilylbis-1
-(2-methylindenyl) zirconium dichloride,
Dimethylsilylbis-1- (2-methyltetrahydroindenyl) zirconium dichloride, dimethylsilylbis
-1-indenyl zirconium dichloride, dimethylsilylbis-1-indenyldimethylzirconium, dimethylsilylbis-1-tetrahydroindenylzirconium dichloride, diphenylmethylene-9-fluorenylcyclopentadienyl zirconium dichloride, diphenylsilylbis- 1-indenyl zirconium dichloride, ethylenebis-1- (2-methyl-4,5-benzindenyl) zirconium dichloride, ethylenebis-1- (2-
Methyl-4-phenylindenyl) zirconium dichloride, ethylenebis-1- (4,7-dimethylindenyl) zirconium dichloride, ethylenebis-1-indenylzirconium dichloride, ethylenebis-1-tetrahydroindenylzirconium dichloride, ethylene Bis-1- (2-methyltetrahydroindenyl) zirconium dichloride, ethylenebis-1- (2-methyl-4,5-benzo-6,7-dihydroindenyl) zirconium dichloride, ethylenebis-1- (2- Methylindenyl) zirconium dichloride, and the alkyl or aryl derivatives of each of these metallocene dichlorides.

Activate this single center catalyst system
For this purpose, a suitable cocatalyst is used. Of the metallocene of formula I
Suitable co-catalysts are organoaluminum compounds, especially
Aluminoxane, or R^{twenty two} _xNH_4-xBR^{twenty three} _Four, R^{twenty two} _xPH
_4-xBR^{twenty three} _Four, R^{twenty two} _ThreeCBR^{twenty three} _FourOr BR^{twenty three} _ThreeEtc. aluminum
It is a system that does not contain. In these formulas, x is 1 to 4,
R^{twenty two}Are the same or different, preferably the same, C₁-C_Ten
-Alkyl or C₆-C ₁₈-Is aryl, or
Two groups R^{twenty two}Forms a ring with the atoms connecting them
And the group R^{twenty three}Are the same or different, preferably the same
One C₆-C₁₈-Aryl, which is alkyl, haloa
It may be substituted by alkyl or fluorine. Special
And R^{twenty two}Is ethyl, propyl, butyl or phenyl
Yes and R^{twenty three}Is phenyl, pentafluorophenyl,
3,5-bis (trifluoromethyl) phenyl, mesityl,
Xylyl or tolyl.

These cocatalysts are particularly preferred for use in combination with metallocenes of the formula I in which R ¹ and R ² are each C ₁ -C ₁₀ -alkyl or aryl or benzyl, preferably methyl. It is. Derivative formation to obtain such metallocenes of the formula I can be carried out by methods described in the literature,
For example, it can be carried out by reacting with an alkylating agent such as methyllithium (Organometallics 9 (199
0) 1539; J. Am. Chem. Soc. 95 (1973) 6263).

In addition, a third component is often required to protect against polar catalyst poisons. Organoaluminum compounds such as triethylaluminum, tributylaluminum and the like, and mixtures thereof, are suitable for this purpose. Depending on the manufacturing process, supported single center catalysts can also be used. Due to the high polymerization activity, the support material and cocatalyst residues in the product are 100 p
Catalyst systems which do not exceed a concentration of pm are preferred.

For the preparation of the waxes according to the invention, propene is converted to hydrogen and, if necessary, to 2
It polymerizes in the presence of yet another olefin having 1818 carbon atoms. Examples of comonomers that can be used are ethylene,
1-butene, 1-pentene, 1-hexene, 1-octene, 2-methyl-1-propene, 3-methyl-1-butene, 3-methyl-1-
Penten, 4-methyl-1-pentene, 4-methyl-1-hexene and styrene. It is preferred to polymerize propylene and copolymerize propylene with a 1-olefin having 2 to 10 carbon atoms. Examples of copolymer waxes are propylene-ethylene wax, propylene-1-
Butene wax and propylene-1-hexene wax.

The copolymer waxes contain comonomer in an amount of 0 to 20% by weight, based on the total polymer. The terpolymer wax comprises the main polymer in an amount of at least 80% by weight and the two comonomers are each present in an amount of up to 19% by weight, the sum of these two comonomers being 20% by weight of the total polymer. % Does not exceed. The waxes according to the invention contain unsaturated terminal groups in a proportion of less than 10%, preferably less than 5%.

The wax of the invention can be produced in any suitable type of reactor, for example a loop reactor, an autoclave or a gas-phase reactor. Adjustment of molecular weight
Preferably, rather than by changing the polymerization temperature,
Rather, it is performed by changing the hydrogen pressure at a constant temperature. The polypropylene homopolymer and copolymer waxes according to the invention have a viscosity of 10-100,000 mPas at 170 DEG C. and a narrow molecular weight distribution, less than 5, preferably 3,5.
_Mw / _Mn less than.

[0031]

【Example】

Examples: The following abbreviations are used in the following examples: DSC = Differential Scanning Calorimeter GPC = Gel Permeation Chromatography GC = Gas Chromatography M _w = Weight average molecular weight (g / mol) measured by GPC M _n = Number average molecular weight measured by GPC (g / mol) M _w / M _n = polydispersity Melting point (mp) and heat of fusion (ΔH)
Perkin-Elmer DSC7 at heating / cooling rate of ° C / min
Was measured by DSC measurement using.

The melt viscosity (MV) was measured using a rotary viscometer.
Measured at 0 ° C. Isotactic index (II)
Was measured by IR spectroscopy using the method described in JPLuongo, J. Appl. Polym. Chem., 3, 302 (1960). The chain ends of the polymer are described in Polymer, 1989, Vol. 30, p. 4
As described in 28, was examined by ¹³ C-NMR spectroscopy. If less than 10% of all end groups were isopropenyl end groups, the polymer was described in Table 1 as "saturated". Example 1 In an inert 100 dm ³ volume reactor, propene 30 was added.
kg and 12 mmol of triisobutylaluminum were introduced, the mixture was heated to 70 ° C. with stirring and metered in with 1.0 bar of hydrogen.

In parallel, 15 ml of a 10% strength by weight solution of methylaluminoxane in toluene in ethylene
31 mg of 1 '-(tetrahydroindenyl) zirconium dichloride was dissolved and stirred. The polymerization was started by adding the catalyst solution in small portions and the internal temperature of the reactor was adjusted to 70 ° C. Hydrogen was metered in while monitoring by GC to keep the concentration constant at the initial value. After 1 hour, the polymerization was stopped by the addition of CO _2, the reactor was vented and the product was discharged as a melt. 12.1 kg of PP wax was obtained. By GPC measurement,
A _{Mw of} 3528 and a _Mw / _{Mn of} 2.1 were measured. Table 1 summarizes the characteristic data. Comparative Example 1: Example 1 is repeated, but without supplying hydrogen. Table 1 summarizes the characteristic data. GPC measurements indicated a M _{w of} 12640 and a M _w / M _n of 2.5. Example 2 Example 1 was repeated using 26 mg of dimethylsilylbisindenyl zirconium dichloride and 230 mbar of hydrogen. 9.9 kg of PP wax were obtained. GPC measurements showed a _Mw of 6920 and a _Mw / _Mn of 2.9. Table 1 summarizes the characteristic data. Comparative Example 2 Example 1 was repeated with the exception that 200 mmol of trimethylaluminum were metered in as a solution in toluene instead of hydrogen. Table 1 summarizes the characteristic data. GPC measurement showed a _{Mw of} 24300 and a _Mw / _Mn of 2.8. Example 3 The wax of the above example was heated in a drying oven at 200 ° C. for 4 hours in the presence of air. After cooling the samples, the discoloration was evaluated using a set of comparative samples (grade 1: colorless, grade 6: dark brown). The results of this heating test (Table 1) show that the wax produced in the presence of hydrogen has improved thermal stability.

[0034]

[Table 1]

Claims (2)

[Claims] 1. A polypropylene homopolymer prepared by polymerizing with a metallocene compound in the presence of hydrogen and having an unsaturated chain end of less than 10% and a melt viscosity of 10-100,000 mPas measured at 170 ° C. And the use of copolymer waxes as components for the production of toners. 2. The method according to claim 1, wherein the metallocene compound is a sandwich type chelate compound containing titanium, zirconium or hafnium as a metal atom.