JP3268464B2 - Titanyl phthalocyanine crystal dispersion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a dispersion of a titanyl phthalocyanine pigment. Especially used for printers, etc.
The present invention relates to a dispersion of an electrophotographic photosensitive member material that is effective for LED light and semiconductor laser light.

[0002]

2. Description of the Related Art In recent years, there has been a remarkable development of electronic equipment, and there is an increasing demand for printers and digital copiers used for output from computers. 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 photoconductors such as selenium are not sufficient for this purpose, and many organic photoconductors (OPC) in which phthalocyanines are dispersed have been studied.

It is known that phthalocyanines have different photoelectron characteristics depending on their crystal forms.
Y-type titanyl phthalocyanine, which has a peak at 9.6 degrees, is an excellent material having a high photon efficiency of 0.94 (Japan Hardcopy 89, Proceedings 103, (1989)). However, this material has the disadvantage that the sensitivity is somewhat affected by humidity. There are several ideas for this cause. While studying the excellent physical properties of the Y-type crystal, Fujimaki et al. Found that this material reduced photon efficiency due to reversible dehydration treatment in a heated or dry nitrogen atmosphere. This is because when water is reabsorbed at room temperature and humidity, it recovers again, so the Y-type particles are water-adsorbed crystals, and assist the dissociation of holes and photoelectrons from the titanyl phthalocyanine exciton generated by the exposure of water molecules to light. I do. That is Y
It is speculated that there is one cause of high sensitivity of type titanyl phthalocyanine and a cause of 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 this idea, it is expected that a similar effect can be obtained by adding a compound having an OH group instead of water. We crystallized amorphous titanyl phthalocyanine in the presence of compounds having adjacent OH groups such as ethylene glycol and propylene glycol to obtain the desired titanyl phthalocyanine adduct. These gave excellent photoreceptors with high sensitivity and no humidity dependence as expected. However, these crystals are stable in a powder or a completed photoreceptor without a solvent, but are hardly stable crystals in a dispersion. There is a problem that the performance is deteriorated by being mixed. When the photosensitive drum is manufactured by a technique such as spray coating at the research stage, there is no problem because most of the dispersion is consumed. However, in the future, in the current dip (dipping) coating, only a very small part of the coating liquid will be attached to and removed from the drum, and the preservability of the remaining coating liquid will account for a large proportion of the manufacturing cost. .

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a stable coating solution of titanyl phthalocyanine crystal having good sensitivity and low humidity dependency in view of the above-mentioned circumstances, and to provide a photoreceptor having a low cost. .

[0006]

The object of the present invention has been achieved by adding a compound having an adjacent OH group to a dispersion of a specific titanyl phthalocyanine crystal. The specific titanyl phthalocyanine crystal is an adduct with a compound containing adjacent OH (hereinafter, adjacent diol compound). The addition is apparent from the thermal analysis (TG) of the titanyl phthalocyanine crystal, in which a weight loss is observed at a temperature higher than the boiling point by 100 ° C. or more, and the adjacent OHs are released. From the weight reduction, adjacent diol compound / titanyl phthalocyanine = 1/2.

[0007] Examples of the titanyl phthalocyanine adduct of the adjacent diol compound of the present invention include, but are not limited to, the following.

In the following, adjacent diol compounds, crystal type names,
The 2θ peaks in the X-ray diffraction spectrum are listed as a set. The following tentative names were used for the crystal type names for the sake of organization.

Adjacent diol compound Crystalline 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. The dispersion of the present invention is a dispersion of these adducts of titanyl phthalocyanine with diol compounds. The diol compound is added to the solution to improve the stability. The diol compound may be added before or after the pigment is dispersed. The addition amount of the diol compound is 0.
It may be as high as 01%, preferably 0.1 to 5%. As will be described in the examples, there is a remarkable stabilizing effect. That is, the diol compound adduct of titanyl phthalocyanine is in a metastable state and is in an equilibrium state as shown in the following formula in the dispersion.

[0011] TiOPc + diol compound ⇔ TiOPc adduct It is considered that equilibrium shifts to the right when a small amount of diol compound is added to this system.

The dispersion of the present invention can use a polymer binder. 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, and vinyl chloride. -Vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol-
Examples include formaldehyde resin, styrene-acrylic copolymer resin, styrene-alkyd resin, poly-N-vinylcarbazole, polyvinylbutyral resin, polycarbonate Z resin, ethylcellulose resin, nitrocellulose resin, and polyvinyl alcohol resin. These binders can be used alone or as a mixture of two or more. Examples of the solvent used for the dispersion include acetone, methyl ethyl ketone, cyclohexanone, toluene, dichlorobenzene, dichloromethane, dichloroethane, tetrahydrofuran, dioxane, methanol, ethanol, isopropanol, ethyl acetate, butyl acetate and the like. As a means for preparing the dispersion, a well-known means such as a sand grinder, a ball mill, and ultrasonic waves can be used.

[0013]

EXAMPLES The synthesis examples and examples are described below.

(Synthesis Example 1: Synthesis of E-type TiOPc crystal) (Synthesis of TiOPc-amorphous product) 1,3 diiminoisoindoline; 29.2 g; ortho-dichlorobenzene 200 ml
And 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 standing to cool, the precipitated crystals were filtered and washed with chloroform, 2%
After washing with an aqueous hydrochloric acid solution, washing with water, and washing with methanol, 26.2 g (91.0%) of crude titanyl phthalocyanine was obtained after drying.
Its crystal form is shown in FIG. Then, 20.0 g of the crude titanyl phthalocyanine was added in 200 ml of concentrated sulfuric acid at 5 ° C. or lower.
Stir for hours to dissolve and pour into 4 l of water at 20 ° C. The precipitated crystals were filtered and sufficiently washed with water to obtain 180 g of a wet paste product. The dried and powdered crystal form is in an amorphous state as shown in FIG.

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

(Synthesis Example 2; Synthesis of Q1-type TiOPc) 100 ml of orthodichlorobenzene and 50 ml of 1,2-propanediol were placed in a flask, and 8 g of the above-mentioned 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,
After washing with methanol and drying, 8.4 g of the desired titanyl phthalocyanine crystal was obtained. As shown in FIG. Bragg angle 2θ; maximum peak at 26.6 degrees, but 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 orthodichlorobenzene and 50 ml of 1,2-propanediol were placed in a flask, and 8 g of the titanyl phthalocyanine-amorphous dry powder obtained by the method of Synthesis Example 1 was added thereto. added. The mixture was then heated at reflux for 7 hours. After cooling, the mixture was poured into methanol (800 ml) to precipitate crystals. After filtration, washing with methanol and drying, 8.4 g of the desired titanyl phthalocyanine crystal was obtained. As shown in FIG. A crystal (Q2-type crystal) having a maximum peak at a Bragg angle 2θ; 26.6 degrees as in Synthesis Example 1, but additionally having peaks at 6.9, 7.3, 11.2, 12.9, and 16.0 degrees.

Example 1 2 parts of the chlorofree E-type titanyl phthalocyanine (hereinafter referred to as 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.), and methyl ethyl ketone 100 parts (wt) were pulverized and dispersed by a sand grinder to obtain a dispersion. In anticipation of moisture absorption during long-term use, 0.5 parts of water was added to this. 0.5 parts of ethylene glycol was added thereto to obtain a dispersion of the present invention (sample 1). For comparison, a forced deterioration test was performed for 2 weeks in a 60 ° C. constant temperature box 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. FIG. 6 shows the results. Dispersion sample 1 to which ethylene glycol of the present invention is added
While the sample maintains the crystal form even after the forced deterioration test, the comparative sample (1) has changed to another crystal form. Example 2 3 parts of the titanyl phthalocyanine type E 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 The mixture was pulverized and dispersed by a grinder to obtain a dispersion. To this was added 0.5 parts of ethylene glycol. (Sample 2) Similarly, a dispersion was obtained using the titanyl phthalocyanine Q1 type crystal of the present invention obtained in Synthesis Example 2, and 0.5 part of propylene glycol was added thereto. (Sample 3) Similarly, a dispersion was obtained using the titanyl phthalocyanine Q2 type crystal of the present invention obtained in Synthesis Example 3, and 0.5 part of propylene glycol was added thereto. (Sample 4) As in Example 1, these dispersions of the present invention were subjected to a forced deterioration test together with a comparative dispersion to which no diol was added in a constant temperature box at 40 ° C. for 12 weeks. This dispersion was applied on a slide glass, and the X-ray diffraction spectrum was measured. The results are shown in FIGS. While the dispersion containing the diols of the present invention has no change, the crystal form of the comparative dispersion containing no diols is changing. The diol compound of the present invention of Example 1 was added. A diol-free dispersion liquid compared to the dispersion liquid was applied to an electrophotographic photosensitive member, and the dispersion was prepared immediately after dispersion and after a forced deterioration test, and evaluated for comparison. That is, a polyamide resin (“CM8000” manufactured by Toray Industries, Inc.) was dissolved in methanol and applied to an aluminum-evaporated polyester base to form an undercoat layer having a thickness of 0.2 μm. The above-mentioned chlorofree E-type crystal dispersion liquid (sample 1, and comparative sample (1)) was applied thereon, and the film thickness was 0.2 μm.
Was formed. On the other hand, 1 part of the following carrier transport material (1), 2 parts (wt) of a polycarbonate resin ("Iupilon Z200" manufactured by Mitsubishi Gas Chemical Company) and 0.01 part of silicone oil ("KF-54" manufactured by Shin-Etsu Chemical Co., Ltd.) were added for 1,2 parts. -The solvent was dissolved in 15 parts (wt) of dichloroethane, and this was coated on the carrier generating layer with a blade to form a carrier transport layer having a dry film thickness of 25 µm, thereby producing a photoreceptor.

[0019]

Embedded image

The photoreceptor, photoreceptor sample 1, and photoreceptor comparative sample 1 were prepared immediately after dispersion.

Evaluation: Each sample was evaluated using a paper analyzer EPA-8100 (manufactured by Kawaguchi Electric Co., Ltd.). It is charged for 5 seconds under a discharge condition of -80 μA, and the surface potential [Va] immediately after the charging and the surface potential [V] after being left in the dark for 5 seconds.
i], exposure is performed so that the surface illuminance becomes 2 (lux), and the exposure amount [E1 / 6 (lux.s
ec)]. Further, the formula: D = (Va−Vi) /
The decay rate of potential in a dark place [D
(%)]. The results are shown below.

Va E1 / 6 D Photoreceptor sample 1 prepared immediately after dispersion 1560 0.85 5.2% Comparative photoreceptor sample 1 Prepared immediately after dispersion 1540 0.80 5.2% Photoreceptor sample 1 After forced degradation test 1550 0.86 5.1% Comparative photoreceptor sample 1 forced degradation 1510 0.95 9.0 After the test, the dispersion of the present invention to which the adjacent diol compound was added showed little change in electrophotographic performance immediately after dispersion and after the forced deterioration test, whereas the comparative dispersion without the diol compound did not accelerate. After that, D greatly increases.

[0023]

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

[Brief description of the drawings]

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

FIG. 2 is an X-ray diffraction spectrum 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 of a Q1-type TiOPc crystal.

FIG. 5 is an X-ray diffraction spectrum of a Q2-type TiOPc crystal.

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

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

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

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

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C09B 67/50 G03G 5/06

Claims (5)

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