EP0671026A1

EP0671026A1 - Electrostatic toners containing amphiphilic liquid crystals

Info

Publication number: EP0671026A1
Application number: EP93924082A
Authority: EP
Inventors: Peter Neumann; Claudia Kraeh; Karin Heidrun Beck
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 1992-11-07
Filing date: 1993-10-29
Publication date: 1995-09-13
Also published as: WO1994011789A1; DE4237661A1; JPH08503083A; CA2147171A1

Abstract

The invention concerns electrostatic toners containing a polymeric binder and, as charge stabilizer, a compound of formula (I) in which n is 2 to 6; Q is a 2- to 6-valent group derived from benzene, cyclohexane, naphthalene, triphenylene or perylene; X is a chemical bond, oxygen, sulphur, sulphonyl, carbonyl or a group of the formula O-CO, CO-O, NH-CO or CO-NH; L is a bridging member; R?1, R2 and R3¿ are C¿1?-C4 alkyl or C5-C7 cycloalkyl, or R?1 and R2¿ together are 1,4-butylene, 1,5-pentylene or 1,5-(3-oxapentylene), or the group (a) is the pyridinium or 3-carboxylpyridinium ion; and An-O is the anion equivalent. The invention also concerns the use of such compounds as charge stabilizers in electrostatic toners.

Description

Electrostatic toners containing amphiphilic liquid crystals

description

The present invention relates to new electrostatic toners containing a polymeric binder and a charge of a compound of formula I as a charge stabilizer

in the

n 2 to 6,

Q is a 2- to 6-valent radical which is derived from benzene, cyclohexane, naphthalene, triphenylene or perylene,

X is a chemical bond, oxygen, sulfur, sulfonyl, carbonyl or a radical of the formula O-CO, CO-O, NH-CO or CO-NH,

LC ₃ -C ₂ o-alkylene or a radical of the formula IΛ-XL ² , in which L ^{1 is} C ₂ -C ₃ alkylene and L ^{2 is} C ₂ -C ₂ o-alkylene and X, with the exception of the chemical bond, is the has the above meaning,

R ¹ , R ² and R ³ independently of one another are each C ¹ -C ₄ -alkyl, C ₅ -C -cycloalkyl or R ¹ and R ² together 1,4-butylene, 1,5-pentylene or 1,5- ( 3-0xapentylene) or the rest

θ / / ^Rl

N - R ²

\

R ³

Pyridinium or 3-carboxylpyridinium and

Where _n θ ^{ö is} the equivalent of an anion, and the use of the above-mentioned compounds as charge stabilizers in electrostatic toners.

Latent electrostatic image recordings are developed by inductively depositing the toner on the electrostatic image. The charge stabilizers stabilize the electrostatic charge on the toner. This makes the image more vivid and sharper.

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

Ability to develop the latent electrostatic

Picture to a brightly colored visible picture. - Easily distributable in the toner preparation in order to produce a trouble-free, contour-sharp, uniform image.

Insensitivity to moisture.

High thermal stability.

US Pat. No. 4,851,561 discloses electrostatic toners which have benzyldimethylalkylammonium salts as charge stabilizers, with 3,5-dimethoxycarbonylbenzenesulfonate as the anion.

However, it has been shown that the charge stabilizers of the prior art frequently have deficiencies in their requirement profile.

The object of the present invention was therefore to provide new electrostatic toners which have charge stabilizers and which have advantageous application properties.

We have found that this object is achieved by the electrostatic toners described in the introduction, containing amphiphilic liquid crystals of the formula I, as charge stabilizers.

All alkyl or alkylene groups occurring in the above formula I can be both straight-chain and branched.

Suitable radicals L and L ² are, for example, (CH ₂ ) ₃ , (CH ₂ ) ₄ , (CH ₂ ) ₅ , {CE ₂ ) ₆ ,

(CH ₂ ) ₇ , (CH ₂ ) ₈ , (CH ₂ ) ₉ , (CH ₂ ) ιo, (CH ₂ ) _n , (CH ₂ ) ₁₂ , (CH ₂ ) ι ₃ , (CH ₂ ) ₁₄ , ( CH ₂ ) i5, (CH ₂ ) i6r (CH ₂ ) i7, (CH ₂ ) _lβ , (CH ₂ ) i9, (CH ₂ ) ₂₀ , CH (CH ₃ ) CH ₂ or CH (CH ₃ ) CH (CH ₃ ). L ¹ are, for example, (CH ₂ ) ₂ , (CH ₂ ) ₃ or CH (CH ₃ ) CH. L ² radicals are furthermore, for example, (CH ₂ ) ₂ .

R ¹ , R ² and R ³ are, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, cyclopentyl, cyclohexyl or cycloheptyl.

Suitable anions based on the equivalent of an anion (An) are, for example, halide ions such as chloride, bromide or iodide, cyanide, thiocyanate, tetrafluoroborate, methanesulfonate,

Benzenesulfonate, methylbenzenesulfonate, sulfate or hydrogen sulfate.

If the rest

_R ι

© /

N - R ²

3-Carboxylpyridinium means, no external anion is necessary, since then the compound of formula I is present as betaine:

Electrostatic toners containing a compound of the formula I in which n is 2 or 4 and Q are a 2 or 4-valent radical which is derived from benzene are preferred.

Also preferred are electrostatic toners containing a compound of the formula I in which X is a radical of the formula O-CO or CO-O.

Also preferred are electrostatic toners containing a compound of the formula I in which L is Cs-Cis-alkylene, in particular C ₉ - or Cχo-alkylene.

Electrostatic toners containing a compound of the formula I in which L is unbranched C ₃ -C ₂ o-alkylene are particularly noteworthy.

REPLACEMENT LEAF The amphiphilic liquid crystals of the formula I are known per se and are described, for example, in EP-A-199 211. They are manufactured using the methods mentioned there.

The following is an example of the synthesis route for compounds of the formula I in which Q is a 2- or 4-valent radical derived from benzene and X is a radical of the formula CO-O or O-CO .

You can e.g. Benzene-1,2,4,5-tetracarboxylic acid dianhydride with an alcohol of formula II

HO-L-Hal (II),

in which L has the meaning given above and Hai means chlorine or bromine, implement and the resulting tetraester of the formula III

in which L and shark each have the abovementioned meaning, with a nitrogen-containing compound of the formula IV

(IV),

in which R ¹ , R ² and R ³ each have the meaning given above, bring to reaction.

One can also start from hydroquinone and this with an acid halide of the formula V

Hal-CO-L-Hal (V),

in which Shark and L each have the abovementioned meaning, implement and convert the resulting ester of the formula VI

REPLACEMENT LEAF

in which shark and L each have the meaning given above, react with the amine IV.

The proportion of the compounds of the formula I in the electrostatic toner is generally from 0.01 to 10% by weight, based on the weight of the toner.

The polymeric binders contained in the new electrostatic toners are known per se. They are generally thermoplastic and have a softening point of 40 to 200 ° C., preferably 50 to 130 ° C. and in particular 65 to 115 ° C. Examples of 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 abovementioned compounds of the formula I and the polymeric binders, the toners according to the invention can contain colorants, magnetically attractable material, waxes and flow agents in known amounts.

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 the colorant present in the toner does not exceed 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 0 ₄ , in which Me is a divalent metal, for example iron, cobalt, zinc, nickel or manganese.

REPLACEMENT LEAF The toners according to the invention are produced by customary processes, for example by mixing the constituents in a kneader and then pulverizing or by melting the polymeric binder or a mixture of the polymeric binders, then finely dividing one or more compounds of the formula I , and the other additives, if USAGE ^¬ det, in the molten resin using methods known for this purpose, mixing and kneading machines, subsequent cooling of the melt to a solid mass, and finally grinding the solid mass to give particles of the desired particle size (usually 0.1 to 50 μm). It is also possible to suspend the polymeric binder and the charge stabilizer in a common solvent and to add the other additives to the suspension. The suspension can thus be used as a liquid toner.

However, the liquid can also be spray-dried in a manner known per se, the solvents evaporated or the liquid freeze-dried and the solid residue ground into particles of the desired particle size.

It is also possible not to dissolve the compounds of the formula I used as charge stabilizers, but rather to disperse them finely in the solution of the polymeric binder. The toner preparation obtained in this way can then be used in a xerographic image recording system, for example in accordance with US Pat. No. 4,265,990.

The compounds of formula I mentioned above are advantageous charge stabilizers. They generally satisfy the application profile initially mentioned and are particularly distinguished by the fact that, when added to a toner preparation, they give it a favorable electrostatic charging profile, i.e. the toners can be quickly and highly charged. The charge stabilizers to be used according to the invention furthermore ensure that the charge is kept constant at a high level.

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

A) Production of the amphiphilic liquid crystals

Example St.

a) 25.5 g (117 mmol) of benzene-1, 2, 4, 5-tetracarboxylic acid dianhydride, 120 g (478 mmol) of 11-bromundecanol and a catalytic amount of p-toluenesulfonic acid were dissolved in 1 1 of toluene and heated under reflux on a water separator . As soon as no more water was separated, toluene was reduced

REPLACEMENT LEAF Pressure distilled off. The residue was taken up in methyl tert-butyl ether, filtered and the ether solution was shaken out with 0.1 N hydrochloric acid, saturated aqueous sodium hydrogen carbonate solution and water. After drying with magnesium sulfate, the solvent was distilled off. The

Crude product (45.2 g brown oil) was dissolved in hot ethanol and allowed to crystallize in the refrigerator. 32 g (67% of theory) of a compound of the formula were obtained

in the form of colorless crystals with a melting point of

31 ° C.

Elemental analysis: calc. : C 54, 6 H 7, 6 Br 26, 9 found : C 54, 8 H 7, 8 Br 26, 8

b) 13.5 g (11.4 mmol) of the compound described under a) were mixed with 12.0 g (92.0 mmol) of 45% strength by weight aqueous trimethylamine solution in 250 ml of acetonitrile at 50 ° C. stirred until no more educt could be detected (TLC control). 250 ml of methyl tert-butyl ether were added to the reaction mixture and the precipitate formed was filtered off with suction. 8.9 g (55% of theory) of a compound of the formula were obtained

in the form of colorless crystals with a melting point of 180 ° C (dec.).

The compounds of the formula listed in Table 1 below are used in an analogous manner

E ^l - (CH ₂ ) CO-0 (CH ₂ ) _n -E ^l

E ¹ - (CH ₂ ) CO-0 (CH ₂ ) uE ¹

receive,

REPLACEMENT LEAF Table 1

The bromides described in Examples Hl, H2, H3 and H5 were converted into the corresponding tetrafluoroborates by reaction with sodium tetrafluoroborate in water. They were all oil.

Example H6

a) 19.4 g (0.18 mol) of hydroquinone and 116 g (0.42 mol) of 11-bromo-decanoyl chloride were heated to 150 ° C. with stirring for 30 minutes. After cooling, the mixture was poured into water, the precipitate formed was filtered off, washed with ether and then dried. 101 g (93% of theory) of a compound of the formula were obtained

0-CO- (CH ₂ ) ₁₀ Br

with a melting point of 73 ° C.

b) 6.9 g (11.4 mmol) of the compound described under a) were mixed with 12.0 g (92.0 mmol) of 45% strength by weight aqueous trimethylamine solution in 250 ml of acetonitrile at 50 ° C. stirred until no more educt could be detected (TLC control). 250 ml was added

REPLACEMENT LEAF Methyl tert-butyl ether to the reaction mixture and suctioned off the precipitate formed. 4.2 g (51% of theory) of a compound of the formula were obtained

(CH ₃ ) ₃ Br Θ

(CH ₃ ) ₃ Br ©

in the form of colorless crystals with a melting point of 91 ° C.

The compounds of the formula listed in Table 2 below are used in an analogous manner

O-CO- (CH ₂ ) O-OC (CH ₂ ) ι ₀ E ₂

receive,

Table 2

REPLACEMENT LEAF B) application

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

I. Production of the toners

Example AI

10

0.2 g of the compound from Example H 2 were introduced into a solution of 10 g of an uncrosslinked styrene / butyl acrylate resin in 100 ml of p-xylene at room temperature and then freeze-dried.

15

Example A2

10 g of a non-crosslinked styrene / butyl acrylate resin and 0.2 g of the compound from Example H 2 were mixed intensively in a mixer, kneaded at 120 ° C., extruded and ground. Toner particles with an average particle size of 50 μm were produced by screening.

II. Development of the developer and testing

25

To produce a developer, 99% by weight of a steel carrier, which had an average particle size of 100 μm, was precisely weighed in with 1% by weight of the toner and activated on a roller block in a period specified below. After that was

30 determines the electrostatic charge of the developer. About 5 g of the activated developer were filled into a hard-blow-off cell, which was electrically connected to an electrometer, in a commercial q / m meter (Epping GmbH, Neufahrn). The mesh size of the sieves used in the measuring cell was

35 80 μm.

This ensured that the toner was blown out as completely as possible, but the carrier remained in the measuring cell. Through a strong air flow (approx. 4,000 cm ³ / min) and at the same time

After suction, the toner was almost completely removed from the carrier particles, the latter remaining in the measuring cell. The charge on the carrier was registered on the electrometer. This corresponded to the amount of charging of the toner particles, only with the opposite sign. The amount of q with the opposite sign was therefore used to calculate the q / m value. By

REPLACEMENT LEAF Weighing out the measuring cell, the mass of blown-off toner was determined and the electrostatic charge q / m was calculated from it,

The charge determined on the toners is summarized in Table 3 below.

Table 3

* The toner was prepared either by freeze-drying according to Example AI (marked "G" in the table) or by kneading at a temperature above the softening point of the resin according to Example A2 (in the table with "K" marked).

REPLACEMENT LEAF

Claims

1. Electrostatic toners containing a polymeric binder and a charge of a compound of formula I as a charge stabilizer

in the

2 to 6,

a 2- to 6-valent radical which is derived from benzene, cyclohexane, naphthalene, triphenylene or perylene,

LC ₃ -C ₂ o-alkylene or a radical of the formula L ^! XL ² , in which L ^{1 is} C ₂ -C ₃ alkylene and L ^{2 is} C ₂ -C ₂ alkylene and X, with the exception of the chemical bond, has the abovementioned meaning,

R ¹ , R ² and R ³ independently of one another are each C ¹ -C ₄ -alkyl, C ₅ -C ₇ cycloalkyl or R ¹ and R ² together 1,4-butylene, 1,5-pentylene or 1, 5- (3rd -Oxapentylene) or the rest

R ^l

• /

N - R ²

\

R ³

Pyridinium or 3-carboxylpyridinium and

REPLACEMENT LEAF 2. Electrostatic toner according to claim 1, containing a compound of formula I in which

n 2 or 4 and

Q is a 2- or 4-valent radical derived from benzene.

3. Electrostatic toner according to claim 1, containing a compound of formula I, in which X is a radical of the formula O-CO or CO-O.

4. Electrostatic toner according to claim 1, containing a compound of formula I in which L is Ce-Cis-alkylene.

5. Electrostatic toner according to claim 1, containing 0.01 to 10 wt .-%, based on the weight of the toner, a compound of formula I.

6. Use of the compounds of formula I according to claim 1 as charge stabilizers in electrostatic toners.

REPLACEMENT LEAF