JPH061924A - Dispersion of titanyl phthalocyanine crystal - Google Patents

Abstract

PURPOSE:To obtain the subject dispersion of a titanyl phthalocyanine crystal, excellent in sensitivity, exhibiting a low humidity dependency and capable of providing a low-cost photoreceptor by adding a compound having mutually adjacent OH groups to a dispersion of a specified titanyl phthalocyanine crystal. CONSTITUTION:Amorphous titanyl phthalocyanine is subjected to crystal exchange in the presence of a 1 to 3C compound (hereinafter abbreviated to 'adjacent diol compound') having mutually adjacent OH groups so as to obtain a crystal composed of a titanyl phthalocyanine adduct, e.g. an ethylene glycol- titanyl phthalocyanine adduct, exhibiting peaks, at least, at 7.4 deg., 11.0 deg., 17.9 deg., 20.1 deg., 26.5 deg. and 29 deg.C Bragg angle (2theta+ or -0.2) in its X-ray diffraction spectrum in which the standard is CuKalpha. The obtained titanyl phthalocyanine adduct crystal is dissolved in a solvent (e.g. methyl ethyl ketone or tetrahydrofuran), as necessary, in the presence of a polymer binder (e.g. butyral resin). The resultant solution is ground and dispersed in a sand grinder, etc., and the adjacent diol compound is added to the obtained dispersion, thus producing the objective dispersion of the crystal, improved in stability.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a dispersion of a titanyl phthalocyanine pigment. Especially used for printers,
The present invention relates to a dispersion liquid of an electrophotographic photosensitive material effective for LED light and semiconductor laser light.

[0002]

2. Description of the Related Art In recent years, the development of electronic equipment has been remarkable, and the demand for printers and digital copying machines used for computer output is increasing. These devices require a photoconductor that is sensitive to red to near infrared light because a semiconductor laser or LED is used as a light source.

Conventional inorganic photoreceptors such as selenium series are not sufficient for this purpose, and many organic photoreceptors (OPC) in which phthalocyanines are dispersed have been investigated.

It is known that the phthalocyanines have different photoelectron characteristics depending on their crystal form, and especially at 27.2 degrees.
Y-type titanyl phthalocyanine, which has a peak at 9.6 degrees, is an excellent material with a high photon efficiency of 0.94 (Japan Hardcopy 89, Proceedings 103, (1989)). However, this material has a drawback that the sensitivity is somewhat affected by humidity. There are several thoughts on this cause. While studying the excellent physical properties of Y-type crystals, Fujimaki et al. Found that this material causes a decrease in photon efficiency due to reversible dehydration treatment by heating or dry nitrogen atmosphere. This is because Y-type particles are crystals that adsorb water because they recover again when water is reabsorbed at room temperature and normal humidity, which assists the dissociation of holes and photoelectrons from the titanyl phthalocyanine excitons generated when the water molecules are exposed to light. To do. That is Y
It is speculated that it is one of the causes of the high sensitivity of type titanyl phthalocyanine, and may cause the sensitivity decrease at low humidity (Y.Fujimaki: IS &T's 7th International Co.
ngress on Advance in Nonimpact Printing Technologi
es, Paper Summaries, 269, (1991)). From that viewpoint, it is expected that the same effect will be obtained by adding a compound having an OH group instead of water. We obtained the target titanyl phthalocyanine adduct by crystallizing amorphous titanyl phthalocyanine in the presence of compounds having adjacent OH groups such as ethylene glycol and propylene glycol. As expected, these products gave excellent photoreceptors with high sensitivity and no humidity dependence. However, these crystals are stable in powder or a completed photoreceptor without a solvent, but it is difficult to say that they are stable crystals in a dispersion liquid. There is a problem that performance will deteriorate due to mixing. When the photosensitive drum is manufactured by a technique such as spray coating in the research stage, most of the dispersion liquid is consumed, so there is no problem. However, in the future, it will be left untouched, and in the current dip (immersion) coating, only a small part of the coating liquid adheres to the drum and is carried away, and the storability of the remaining coating liquid accounts for a large proportion of the manufacturing cost. .

[0005]

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a stable coating solution of titanyl phthalocyanine crystals having high sensitivity and less humidity dependency, and to provide a low cost photoreceptor. .

[0006]

Structure of the Invention and Its Function The object of the present invention was achieved by adding a compound having adjacent OH groups to a dispersion of specific titanyl phthalocyanine crystals. The specific titanyl phthalocyanine crystal is an adduct with a compound containing an adjacent OH (hereinafter referred to as an adjacent diol compound). The fact that the titanyl phthalocyanine crystals are added can be seen from the fact that the thermal analysis (TG) of the titanyl phthalocyanine crystals shows a weight reduction at a temperature higher than the boiling point by 100 ° C. or more and releases the adjacent OHs. Adjacent diol compound / titanyl phthalocyanine = 1/2 from the weight reduction.

Examples of the titanyl phthalocyanine adduct of the adjacent diol compound of the present invention include, but are not limited to, the following.

Below, the adjacent diol compound, crystal type name,
The 2θ peaks in the X-ray diffraction spectrum are listed as a set. For the sake of simplification, the crystal form name uses the following tentative name.

Adjacent diol compound Crystal type X-ray diffraction peak (degree) Ethylene glycol E type 7.4, 11.0, 17.9, 20.1, 26.5, 29.0 1,2-Propanediol Q1 type 12.9, 16.2, 24.4, 26.6 Q2 type 6.9, 7.3 , 16.0, 26.6 The above X-ray diffraction spectrum was measured under the following conditions.

X-ray tube Cu voltage 40.0 kv current 100 mA start angle 6.00 deg. Stop angle 35.00 deg. Step angle 0.020 deg. Measurement time 0.50 sec. Dispersion liquid of the titanyl phthalocyanine diol compound adduct is dispersion of the present invention. This is intended to improve the stability by adding the diol compound to the liquid. The diol compound may be added before the pigment is dispersed or after the pigment is dispersed. The amount of the diol compound added was 0.
It may be as high as 01%, preferably 0.1-5%. As described in Examples, the stabilizing effect is remarkable. That is, the titanyl phthalocyanine diol compound adduct is in a metastable state in the equilibrium state as shown in the following formula in the dispersion.

TiOPc + diol compound ⇔ TiOPc adduct It seems that the equilibrium is biased to the right when a small amount of diol compound is added to this system.

A polymer binder may be used in the dispersion of the present invention. Examples of the binder include polycarbonate resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, vinyl chloride. -Vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol-
Examples thereof include formaldehyde resin, styrene-acrylic copolymer resin, styrene-alkyd resin, poly-N-vinylcarbazole, polyvinyl butyral resin, polycarbonate Z resin, ethyl cellulose resin, nitrocellulose resin, polyvinyl alcohol resin and the like. These binders can be used alone or as a mixture of two or more kinds. Acetone, methyl ethyl ketone, cyclohexanone, toluene, dichlorobenzene, dichloromethane, dichloroethane, tetrahydrofuran, dioxane, methanol, ethanol, isopropanol, ethyl acetate, butyl acetate and the like can be used as the solvent for the dispersion liquid. Well-known means such as a sand grinder, a ball mill, and an ultrasonic wave can be used as a means for producing a dispersion liquid.

[0013]

EXAMPLES Synthesis examples and examples will be described below.

(Synthesis Example 1; Synthesis of E-type TiOPc crystal) (Synthesis of TiOPc-amorphous product) 1,3 diiminoisoindoline; 29.2 g of 200 ml of ortho-dichlorobenzene
20.4 g of titanium tetra-n-butoxide was added, and the mixture was heated at 150 to 160 ° C. for 5 hours under a nitrogen atmosphere. After allowing to cool, the precipitated crystals are filtered and washed with chloroform, 2%
After washing with an aqueous solution of hydrochloric acid, washing with water and washing with methanol, and drying, 26.2 g (91.0%) of crude titanyl phthalocyanine was obtained.
The crystal form of this product is shown in FIG. Then, 20.0 g of this crude titanyl phthalocyanine was mixed with 200 ml of concentrated sulfuric acid at a temperature of 5 ° C. or lower.
Stir for hours to dissolve and pour it into 4 liters of water at 20 ° C. The precipitated crystals were filtered and thoroughly washed with water to obtain 180 g of a wet paste product. The crystal form of this product dried and powdered is in an amorphous state as shown in FIG.

(Synthesis of E-type TiOPc crystal of the present invention) 100 ml of tetrahydrofuran and 50 ml of ethylene glycol were placed in a flask, and the above-mentioned chlorine-free TiOPc was added thereto.
-Add 8 g of amorphous dry powder. The mixture was then stirred at room temperature for 10 hours. Then add this to methanol
It was poured into 800 ml to precipitate crystals. The crystals were filtered, washed with methanol, and dried to obtain 8.4 g of desired titanyl phthalocyanine crystals. As shown in FIG. Bragg angle 2θ; 7.4,
It has peaks at 11.0, 17.9, 20.1, 26.4, 29.0 degrees (E
Type crystal).

(Synthesis Example 2; Synthesis of Q1 type TiOPc) 100 ml of ortho-dichlorobenzene and 50 ml of 1,2-propanediol were placed in a flask, and 8 g of the above titanyl phthalocyanine-amorphous dry powder was added thereto. The mixture was then stirred at room temperature for 10 hours. After standing overnight, this was poured into 800 ml of methanol to precipitate crystals. Filtered,
The crystals were washed with methanol and dried to obtain 8.4 g of desired titanyl phthalocyanine crystals. As shown in FIG. Bragg angle 2θ; maximum peak at 26.6 degrees, but other 12.9, 1
It is a crystal (Q1 type crystal) having a peak at 6.2 degrees.

(Synthesis Example 3; Synthesis of Q2-type TiOPc) 100 ml of ortho-dichlorobenzene and 50 ml of 1,2-propanediol were placed in a flask, and 8 g of titanyl phthalocyanine-amorphous dry powder obtained by the method of Synthesis Example 1 was added to the flask. added. The mixture was then heated to reflux for 7 hours. After allowing to cool, this was poured into 800 ml of methanol to precipitate crystals. The crystals were filtered, washed with methanol, and dried to obtain 8.4 g of desired titanyl phthalocyanine crystals. As shown in FIG. Similar to Synthesis Example 1, it is a crystal (Q2 type crystal) having a maximum peak at 26.6 degrees in Bragg angle 2θ and other peaks at 6.9, 7.3, 11.2, 12.9, 16.0 degrees.

Example 1 2 parts of the chlorfree E-type titanyl phthalocyanine (hereinafter TiOPc) crystal (FIG. 3) of the present invention obtained in Synthesis Example 1, 1 part of butyral resin (“BX-1” manufactured by Sekisui Chemical Co., Ltd.), methyl ethyl ketone 100 parts (wt) was pulverized and dispersed by a sand grinder to obtain a dispersion liquid. Expected to absorb moisture after long-term use, 0.5 parts of water was added to this. 0.5 part of ethylene glycol was added thereto to obtain a dispersion liquid (Sample 1) of the present invention. For comparison, a forced deterioration test was carried out for 2 weeks in a constant temperature box at 60 ° C. together with the dispersion liquid (comparative sample (1)) to which ethylene glycol was not added. Apply the dispersion on a glass slide,
The X-ray diffraction spectrum was measured. Results are shown in FIG. Dispersion sample 1 containing ethylene glycol of the present invention
In contrast to maintaining the crystal form after the forced deterioration test, Comparative Sample (1) has changed to another crystal form. Example 2 3 parts of the titanyl phthalocyanine E-type crystal of the present invention obtained in Synthesis Example 1, 20 parts of a silicone resin (“KR-5240, 15% xylene butanol solution” manufactured by Shin-Etsu Chemical Co., Ltd.), and 100 parts (wt) of methyl ethyl ketone were sanded. It was pulverized and dispersed by a grinder to obtain a dispersion liquid. To this was added 0.5 part of ethylene glycol. (Sample 2) Similarly, a titanyl phthalocyanine Q1 type crystal of the present invention obtained in Synthesis Example 2 was used to obtain a dispersion liquid, to which 0.5 part of propylene glycol was added. (Sample 3) Similarly, a titanyl phthalocyanine Q2-type crystal of the present invention obtained in Synthesis Example 3 was used to obtain a dispersion liquid, to which 0.5 part of propylene glycol was added. (Sample 4) These dispersions of the present invention were subjected to a forced deterioration test for 12 weeks in a constant temperature box of 40 ° C. together with a comparative dispersion in which no diol was added as in Example 1. This dispersion was applied on a slide glass and the X-ray diffraction spectrum was measured. The results are shown in FIGS. The crystal form is changing in the comparative dispersion liquid in which the diols of the present invention are not changed, whereas the crystal form is changing in the comparative dispersion liquid in which the diols of the present invention are not added. Reference Example The diol compound of the present invention of Example 1 was added. The dispersion liquid containing no diol, which was used for comparison with the dispersion liquid, was applied to the electrophotographic photosensitive member, and the dispersion liquid was prepared on the photosensitive member immediately after the dispersion and after the forced deterioration test for comparative evaluation. That is, a polyamide resin (“CM8000” manufactured by Toray Industries, Inc.) was dissolved in methanol and coated on an aluminum vapor-deposited polyester base to form an undercoat layer having a thickness of 0.2 μm. The above-mentioned chloro-free E-type crystal dispersion liquid (Sample 1, and comparative sample (1)) was applied to this to form a film with a thickness of 0.2 μm.
The carrier generation layer of was formed. On the other hand, 1 part of the following carrier-transporting substance (1), 2 parts (wt) of a polycarbonate resin (“Upilon Z200” manufactured by Mitsubishi Gas Chemical Co., Ltd.) and 0.01 part of silicone oil (“KF-54” manufactured by Shin-Etsu Chemical Co., Ltd.) -Dissolved in 15 parts by weight of dichloroethane (wt), and blade coating this on the carrier generation layer to form a carrier transport layer having a dry film thickness of 25 μm to prepare a photoreceptor.

[0019]

[Chemical 1]

The photoconductor, the photoconductor sample 1, and the photoconductor comparison sample 1, which were prepared immediately after dispersion, were used.

Evaluation: Each sample was evaluated using a paper analyzer EPA-8100 (manufactured by Kawaguchi Electric Co., Ltd.). -Electrically charged for 5 seconds under a discharge condition of -80 μA, surface potential immediately after charging [Va], surface potential after leaving for 5 seconds in the dark [V
i], exposure so that the surface illuminance becomes 2 (lux, and the exposure amount from the surface potential of -600V to -100V [E1 / 6 (lux.s
ec)]. Further formula: D = (Va-Vi) /
Va × 100 for attenuation of potential in the dark [D
(%)] Was calculated. The results are shown below.

Va E1 / 6 D Photoconductor sample 1 made immediately after dispersion 1560 0.85 5.2% Comparative photoconductor sample 1 made immediately after dispersion 1540 0.80 5.2% Photoconductor sample 1 after forced deterioration test 1550 0.86 5.1% Comparative photoconductor sample 1 forced deterioration After the test 1510 0.95 9.0 The electrophotographic performance of the dispersion liquid of the present invention to which the adjacent diol compound was added hardly changed immediately after the dispersion or after the forced deterioration test, whereas the comparative dispersion liquid containing no diol compound did the accelerated deterioration test. After that, D will increase significantly.

[0023]

According to the present invention, it is possible to provide a stable coating solution of titanyl phthalocyanine crystals having high sensitivity and low humidity dependency, and thus it is possible to provide a photoreceptor having a low cost.

[Brief description of drawings]

FIG. 1 is an X-ray diffraction spectrum diagram of crude TiOPc used in the synthesis of the present invention.

FIG. 2 is an X-ray diffraction spectrum diagram of TiOPc-amorphous obtained from crude TiOPc.

FIG. 3 is an X-ray diffraction spectrum of an E-type TiOPc crystal.

FIG. 4 is an X-ray diffraction spectrum diagram of a Q1-type TiOPc crystal.

FIG. 5: X-ray diffraction spectrum of Q2-type TiOPc crystal

FIG. 6 is an X-ray diffraction spectrum diagram of a raw sample and a forced deterioration sample of Sample 1 and Comparative Sample (1).

FIG. 7 is an X-ray diffraction spectrum diagram of a raw sample and a forced deterioration sample of Sample 2 and Comparative Sample (2).

FIG. 8 is an X-ray diffraction spectrum diagram of a raw sample and a forced deterioration sample of Sample 3 and Comparative Sample (3).

FIG. 9 is an X-ray diffraction spectrum diagram of a raw sample and a forced deterioration sample of Sample 4 and Comparative Sample (4).

Claims (5)

[Claims] 1. A dispersion liquid of titanyl phthalocyanine crystals, wherein a compound having adjacent OH and having 3 or less carbon atoms (adjacent diol compound) is added. 2. A dispersion of titanyl phthalocyanine adduct, wherein the compound having adjacent OH is ethylene glycol or propylene glycol. 3. An ethylene glycol-titanyl phthalocyanine adduct having a Bragg angle (2θ ± 0.2) of at least 7.4, 11. in an X-ray diffraction spectrum for CuKα.
The dispersion according to claim 1 or 2, which is a crystal having a peak at 0, 17.9, 20.1, 26.5, 29.0 degrees. 4. The 1,2-propanediol-titanyl phthalocyanine adduct has a Bragg angle (2θ ± 0.2) of at least 12.9,1 in an X-ray diffraction spectrum for CuKα.
The dispersion according to claim 1 or 2, which is a crystal having peaks at 6.2, 24.4, and 26.6 degrees. 5. A propylene glycol-titanyl phthalocyanine adduct having a Bragg angle (2θ ± 0.2) of at least 6.9, 7. in an X-ray diffraction spectrum with respect to CuKα.
The dispersion according to claim 1 or 2, which is a crystal having peaks at 3, 16.0 and 26.6 degrees.