JP2861022B2 - Metal-free phthalocyanine, production method thereof, and electrophotographic photoreceptor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a metal-free phthalocyanine, a method for producing the same, and a photoreceptor for electrophotography, and particularly to a near-infrared light such as a semiconductor laser beam. The present invention relates to a photosensitive member having high sensitivity.

(Prior Art) In an electrophotographic photoreceptor using a photoconductive material as a photosensitive material, an inorganic photoconductive material such as selenium, cadmium sulfide, and zinc oxide has conventionally been used. However, these materials generally have poor processability and are highly toxic, and some materials have problems regarding their disposal.

In order to improve the disadvantages of such inorganic materials, research on electrophotographic photoreceptors using an organic compound as a photoconductive substance has been extensively conducted, and it is non-toxic, easy to process, lightweight, and flexible. It has been put to practical use taking advantage of such advantages.

On the other hand, in recent years, as information processing has become more sophisticated and faster, a non-impact page printer using a semiconductor laser as a light source as a computer output terminal, that is, a so-called laser beam printer, has been actively developed. There is also an active movement toward digitalization of copiers. The photoconductive material used in the photoreceptor of these devices is sensitive not only to the oscillation wavelength of the semiconductor laser, but also exhibits flat spectral sensitivity characteristics in the wavelength range before and after that, and the temperature dependence of the oscillation wavelength of the semiconductor laser. It is required to be able to cope with gender. In addition to the electrophotographic properties of the photoconductive material, it is also important in terms of practical use that a material having a certain level of performance can be stably manufactured.

Bisazo and trisazo compounds, phthalocyanine compounds, azurenium salt compounds, squarylium salt compounds, and the like are known as organic photoconductive substances used for these applications. Among them, phthalocyanine-based compounds have been studied extensively because they are relatively easy to synthesize, have no portions that are susceptible to photochemical reactions such as azo bonds, and can be expected to have excellent light resistance.

Phthalocyanine has many metastable states between the thermodynamically most stable β-form and the unstable α-form. Among these, X-type metal-free phthalocyanine described in US Pat.
No. 39, a τ-type metal-free phthalocyanine.

(Problems to be Solved by the Invention) As shown in FIG.
Bragg angles of α to X-ray are 7.6, 9.2, 16.8, 17.
It has diffraction peaks at 4, 20.4 and 20.9 degrees. The production method is that α-type metal-free phthalocyanine is mixed with a grinding aid such as salt and an inert organic solvent such as ethylene glycol.
~ 180 ° C, preferably 60 to 130 ° C for 5 to 20 hours by wet kneading, it is necessary to add a post-treatment step to remove the grinding aid and the like, and the process is not only complicated ,
The quality tends to vary, and the stability of the electrophotographic characteristics of the photoreceptor using this as a carrier-generating substance is insufficient.

On the other hand, the X-type metal-free phthalocyanine described in US Pat. No. 3,579,893 has diffraction peaks at CuKα X-ray Bragg angles of 7.5, 9.1, 16.7, 17.3 and 22.3 degrees as shown in FIG. X-type metal-free phthalocyanine is produced by dry grinding of α-type metal-free phthalocyanine,
Although the production method is easier than τ-type metal-free phthalocyanine, it is not always sufficient in terms of product stability.

The phthalocyanine compound has a crystal structure in which disk-shaped molecules are stacked in a columnar shape, and the spacing between molecules, the direction of stacking, the length in the stacking axial direction, the distance between adjacent columnar structures, etc., have important effects on conductivity. And causes a marked change in characteristics when used as a photoreceptor. Differences in these factors appear as differences in X-ray diffraction patterns. The X-type metal-free phthalocyanine also has a different crystal habit from the X-type metal-free phthalocyanine described in US Pat.
Some are known which show a line diffraction spectrum.
For example, JP-A-60-243089 and JP-A-61-115085
JP-A-62-47 discloses an X-type metal-free phthalocyanine produced from a high-purity α-type metal-free phthalocyanine.
No. 054 describes an X-type metal-free phthalocyanine treated with a non-polar organic solvent such as tetrahydrofuran. These are shown in FIG. 4 and FIG.
X-type metal-free phthalocyanine described in the specification of 57989 is X
Not only are the diffraction patterns different from each other, but also the characteristics as a carrier generating substance are different.

However, JP-A-60-243089 and JP-A-61-11
Although the one described in 5085 is relatively excellent in electrophotographic properties and the quality is stable, the production process is extremely complicated and poor in practical use, and it is described in JP-A-62-47054. Although the stability of the quality is good, the primary particles grow by the solvent treatment and the particle diameter is increased as evident from the small half width of the X-ray diffraction peak. When used, the sensitivity of the photoreceptor is low.

(Means for Solving the Problems) Under such circumstances, the present inventors have excellent performance as a carrier-generating substance and have no variation in quality.
As a result of intensive studies on phthalocyanine-based photoconductive materials that are easy to manufacture, the Bragg angle (allowable range ± 0.2 degrees) of CuKα to X-rays is 7.4, 9.0, 16.5, 17.2, 22.1, 2
It has major diffraction peaks at 3.8, 27.0 and 28.4 degrees, and has substantially only two diffraction peaks at Bragg angles (acceptable range ± 0.2 degrees) in the range of 21 to 25 degrees, and infrared absorption has four peaks from 700 cm ^-1 in the range of 760 cm ^-1 in the spectrum, metal-free phthalocyanine peak of 732 cm ^-1 is the most intense peak, it has excellent performance as the carrier generating substance, the product due to manufacturing Have been found to be easy to manufacture and have led to the completion of the present invention.

That is, the present invention provides an electrophotographic photoreceptor having high sensitivity in the oscillation wavelength region of a semiconductor laser and having good quality stability.

Here, “substantially” in the expression “substantially two diffraction peaks” refers to not only a case having a triangular peak as shown in FIG. 1 but also a case where the peak is broadened and trapezoidal. This means that a case where a minute peak or a shoulder peak that does not show a clear vertex exists in the range is also included.

As shown in FIG. 1, the metal-free phthalocyanine in the present invention has a Bragg angle of 7.4, 9.0, 16.
It has an X-ray diffraction spectrum with major diffraction peaks at 5, 17.2, 22.1, 23.8, 27.0 and 28.4 degrees. This metal-free phthalocyanine of the present invention has a Bragg angle of 7.6, 9.
Τ with diffraction peaks at 2, 16.8, 17.4, 20.4, 20.9 degrees
It has no diffraction peaks at Bragg angles of 20.4 and 20.9 degrees with the non-metallic phthalocyanine type, while the Bragg angles of 22.1 and 23.
It differs in having characteristic peaks at 8, 27.0, and 28.4 degrees. Bragg angles of 7.5, 9.2, 16.7, 17.3 and 2
It differs from X-type metal-free phthalocyanine having a diffraction peak at 2.3 degrees in that it has characteristic peaks at Bragg angles of 23.8, 27.0, and 28.4 degrees. Further, three or more metal-free phthalocyanines described in JP-A-60-243089 and JP-A-61-115085 and metal-free phthalocyanines described in JP-A-62-47054 in the range of Bragg angle of 21 to 25 degrees are used. 4
In contrast to having two peaks, the metal-free phthalocyanine of the present invention differs from these metal-free phthalocyanines in that it has substantially only two peaks within the same angle range.

As shown in FIG. 6, the IR absorption spectrum of the metal-free phthalocyanine in the present invention was 732 c in the region of 700 to 760 cm ^−1.
m ^-1 has the strongest four peaks, and in the same region,
X-type metal-free phthalocyanine to 746cm ^-1, τ type metal-free phthalocyanine to 751cm ^-1, metal-free phthalocyanine Sho 62-47054 JP differ as having the strongest peak respectively 720 cm ^-1. It also differs from the metal-free phthalocyanine described in JP ^- A-62-47054 in that it has two peaks in the region of 1320 to 1340 cm ^-1 .

The metal-free phthalocyanine of the present invention is obtained by dry-milling an α-type metal-free phthalocyanine at a temperature of 20 to 80 ° C., preferably 30 to 60 ° C., which is higher than a usual milling condition, using a ball mill or a vibration mill. Can be manufactured. Milling under such high temperatures
This can be achieved by using a jacketed mill.
In the case of a small manufacturing apparatus in which it is difficult to use a mill with a jacket, the temperature around the mill may be kept high. In this case, the ambient temperature should be at least 20 ° C, average 30
It is preferred to keep it at 4040 ° C. A photoreceptor using the metal-free phthalocyanine thus produced can be obtained with less variation in performance such as sensitivity characteristics.

In the electrophotographic photoreceptor of the present invention, other carrier-generating substances may be used in addition to the metal-free phthalocyanine of the present invention as the carrier-generating substance. Examples of the carrier generating substance that can be used in combination include α-type, β-type, γ-type, τ-type,
π-type, τ'-type, η-type, η'-type metal-free phthalocyanine,
JP-A-60-243089, JP-A-61-115085, and non-metallic phthalocyanines described in JP-A-62-47054, copper, titanium, indium, manganese, aluminum, magnesium, tin and other central metals. A phthalocyanine compound, a bisazo and trisazo compound, an anthraquinone compound, a perylene compound, a perinone compound, a polycyclic quinone compound, a dioxazine compound, a quinacridone compound, an azulhenium salt compound,
Squarylium salt compounds, pyrrolopyrrole compounds,
And the like.

In order to form the photosensitive layer of the electronic photographic photoreceptor of the present invention, the above-mentioned carrier generating substance is dispersed in a resin binder, and the obtained coating solution is coated on various known conductive supporting substrates. It may be dried to form a film. As the binder, any material can be used as long as it has a film-forming property, but a polymer having a high dielectric constant and good electric insulation is particularly preferable. Examples of high-molecular polymers include polyester resins, polycarbonate resins, polyvinyl butyral resins, polyvinyl carbazole resins, polystyrene resins, polyvinyl acetate resins, polyvinyl chloride resins, polyvinylidene chloride resins, polyvinylidene fluoride resins, acrylic resins, and methacrylic resins. , Silicone resin, alkyd resin, melamine-alkyd resin, melamine resin, phenol resin, polyamide resin, polyurethane resin, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, vinyl chloride-vinyl acetate copolymer, chloride And vinyl-vinyl acetate-maleic anhydride copolymer.

Examples of solvents that can be used when preparing the coating liquid include hydrocarbons such as toluene, xylene and mineral spirit, ketones such as acetone, methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone and cyclohexanone, dichloromethane, dichloroethane and trichloroethane. , Trichloroethylene, halogenated hydrocarbons such as chlorobenzene, ethers such as tetrahydrofuran, dioxane, monoglyme, diglyme, anisole, alcohols such as methanol, ethanol, propanol, butanol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, cyclohexanol, acetic acid Ester such as ethyl, propyl acetate, butyl acetate, cellosolve acetate, butyl cellosolve acetate, dimethylformamide, - amino such as methylpyrrolidone, water, etc. can be exemplified, further these solvents 2
Mixtures of more than one species can also be used.

The coating liquid can be prepared by dispersing the above-mentioned carrier-generating substance, binder, and solvent using a dispersing means such as a ball mill, a bead mill, a paint shaker, a sand grinder, an attritor, a disperser, and a homomixer.

The formation of the photosensitive layer of the photoreceptor can be performed by spreading the coating solution on a conductive support substrate using a means such as a spin coater, an applicator, a bar coater, a doctor blade, a roll coater, a spray coater, and dipping. it can.

As the structure of the electrophotographic photoreceptor of the present invention, any of a single-layer structure and a laminated structure in which a carrier generation function and a carrier transport function are assigned to different layers can be used. Further, in addition to the above-mentioned layers, an intermediate layer may be provided on the conductive support base, and a surface protective layer may be provided on the uppermost portion. A photoreceptor having a single-layer structure is preferably used as a photoreceptor for positive charging. Can also be used as

As the carrier transporting substance that can be used in the function-separated electrophotographic photoreceptor of the present invention, hydrazone-based compounds, oxazole-based compounds, oxadiazole-based compounds, oxathiazole-based compounds, thiazole-based compounds, thiadiazole-based compounds, triazole-based compounds, Styryl / stilbene compounds, pyrazoline compounds, triarylamine compounds, dibenzylamine compounds, triarylmethane compounds, azine compounds, imidazole compounds, imidazolidine compounds, dicyanomethylene compounds, and the like. it can. Among these compounds, those having an aromatic ring may have a condensed polycyclic structure such as a benzo analog.

Further, in the electrophotographic photoreceptor of the present invention, an electron accepting substance may be present for the purpose of improving sensitivity, reducing residual potential, and the like. Examples of electron accepting substances include succinic acid, maleic acid, benzoic acid, phthalic acid, trimellitic acid, pyromellitic acid, melitic acid, and their acid anhydrides, and the halogens of these carboxylic acids and acid anhydrides. Atoms, nitro groups, cyano groups, and other substituted derivatives with electron-withdrawing substituents, nitrobenzene and its substituted derivatives, benzoquinone and its substituted derivatives, naphthoquinone and its substituted derivatives, anthraquinone and its substituted derivatives, fluorene and its substituted derivatives, salicylic acid and Examples thereof include substituted derivatives thereof, tetracyanoethylene, tetracyanoquinodimethane, and other compounds having high electron affinity. As the addition amount of the electron accepting substance, based on 100 parts by weight of the carrier generating substance,
0.01 to 100 parts by weight, especially 0.1 to 20 parts by weight is preferred.

It was confirmed that the photoreceptor using the metal-free phthalocyanine of the present invention has good sensitivity not only to white light but also to light in the near infrared region. This will be specifically described in the following examples.

(Examples) Hereinafter, the present invention will be described in more detail with reference to examples.
In addition, “parts” means parts by weight.

Example 1 (Production of metal-free phthalocyanine) β-metal-free phthalocyanine was acid pasted by a known method to obtain α-metal-free phthalocyanine. 5000 ml alumina ball mill, 5000 parts of alumina balls with a diameter of 10 mm, α-type metal-free phthalocyanine obtained above
300 parts were charged and milled at about 100 rotations for 150 hours. During this time, the temperature around the ball mill was kept at a minimum of 32 ° C and an average of 40 ° C. After grinding, the contents were discharged and sieved to obtain 290 parts of a metal-free phthalocyanine of the present invention.

The X-ray diffraction pattern of this metal-free phthalocyanine was as shown in FIG. 1, and the infrared absorption spectrum was as shown in FIG. 6 (a).

Comparative Example 1 (Production of X-type metal-free phthalocyanine) The ambient temperature around the ball mill was set to normal temperature (minimum 12 ° C., average 18
° C) to obtain 290 parts of metal-free phthalocyanine in the same manner as in Example 1. The X-ray diffraction pattern of this metal-free phthalocyanine is shown in FIG. 3, and the infrared absorption spectrum is as shown in FIG. 6 (b). It was an X-type metal-free phthalocyanine described in US Pat.

Comparative Example 2 (Production of Conventional Metal-Free Phthalocyanine) A 2000 ml alumina ball was charged with 1700 parts of alumina balls having a diameter of 10 mm, 120 parts of the X-type metal-free phthalocyanine obtained in Comparative Example 1, and 300 parts of tetrahydrofuran. , At about 80 rotations for 24 hours. After discharging the contents and sieving the balls, the mixture is filtered, washed with a small amount of tetrahydrofuran, and dried to obtain a metal-free phthalocyanine 110.
Got a part. The X-ray diffraction pattern of this metal-free phthalocyanine is shown in FIG. 5, and the infrared absorption spectrum thereof is shown in FIG. 6 (c). It was a metal-free phthalocyanine described in JP-A-62-47054.

Example 2 (Production and test of photoreceptor) One part of the metal-free phthalocyanine produced in Example 1 and maleic acid-modified vinyl chloride-vinyl acetate copolymer resin (trade name: SLEX M, manufactured by Sekisui Chemical Co., Ltd.) in a 100 ml glass pot 1 part, methyl ethyl ketone 20 parts, toluene 7 parts,
Then, 40 parts of glass beads having a diameter of 3 mm were charged, and the mixture was shaken and dispersed with a paint conditioner for 2 hours to prepare a carrier generation layer coating solution. On the other hand, 1 part of polycarbonate resin (trade name Panlite L-1250 manufactured by Teijin Chemicals Limited), p
-1 part of diethylaminobenzaldehyde diphenylhydrazine (trade name, manufactured by ABPH Inc.) was dissolved in 10 parts of tetrahydrofuran to prepare a carrier transport layer coating solution.

A carrier generation layer coating solution was applied on a PET film on which aluminum was deposited by a bar coater so as to have a dry film thickness of about 0.5 μm, and dried to form a carrier generation layer. Subsequently, a carrier transport layer coating solution was applied using a bar coater so as to have a dry film thickness of about 20 μm, and dried to form a carrier transport layer, thereby producing an electrophotographic photosensitive member.

The obtained photoreceptor was subjected to an electrostatic copying paper tester EPA-8100.
(Kawaguchi Electric Works) was used to measure the electrophotographic characteristics. The measurement was carried out by performing a −7 kV corona discharge for 3 seconds to negatively charge the surface, leaving it in a dark place for 5 seconds, and then irradiating 780 nm light obtained through a monochromator with a tungsten light source to reduce the surface potential by half. In this cycle, the amount of irradiation energy required for the exposure, ie, the so-called half-exposure amount, was obtained. The characteristics of the electrophotographic photoreceptor in this embodiment are as follows: the initial surface potential is -780 V, and the surface potential after dark decay for 5 seconds is-
678 V (charge retention rate: 87%), half-exposure amount: 5.0 erg / cm ² .

A metal-free phthalocyanine was produced 10 times in accordance with Example 1, and a photoreceptor was prepared in the same manner as described above for each. Electrophotographic characteristics were measured. As a result, the standard deviation of the initial surface potential was 7, and the standard deviation of the half-life exposure was It was 0.15.

Example 3 (Production and test of photoreceptor) 1-phenyl-3- (p-diethylaminostyryl) -5- (p-
Diethylaminophenyl) -2-pyrazolin (trade name AS
An electrophotographic photoreceptor was produced in the same manner as in Example 1 except that PP (Anan Perfumery) was used. When the electrophotographic characteristics were measured, the initial surface potential was -780 V, the charge retention was 88%, and the half-exposure amount was 5.6 erg / cm ² .

Example 4 (Manufacture and test of photoreceptor) 2,5-bis (4'-diethylaminophenyl) -1,3,4-oxadiazole (manufactured by Anan Fragrance Co., Ltd.) was used instead of ABPH as a carrier transporting substance. An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except for the difference. When the electrophotographic characteristics were measured, the initial surface potential was -740 V, the charge retention was 87%,
The half-life exposure amount was 5.4 erg / cm ² .

Comparative Example 3 (Production and Test of Photoconductor) Example 2 was repeated except that the X-type metal-free phthalocyanine produced in Comparative Example 1 was used instead of the metal-free phthalocyanine produced in Example 1 as a carrier-generating substance. An electrophotographic photoreceptor was produced in the same manner. When the electrophotographic characteristics were measured, the initial surface potential was -750 V, and the charge retention was 84.
% And the half-life exposure amount was 5.8 erg / cm ² . In addition, the metal-free phthalocyanine of Comparative Example 1 was manufactured ten times, an electrophotographic photoreceptor was manufactured for each of the phthalocyanines, and the electrophotographic characteristics were measured.
The standard deviation of the initial surface potential is 18, and the standard deviation of the half-life exposure is
0.17, which was larger than that of the electrophotographic photoreceptor manufactured using the metal-free phthalocyanine manufactured in Example 1.

Comparative Example 4 (Production and Test of Photoconductor) Example 2 except that the conventional metal-free phthalocyanine manufactured in Comparative Example 2 was used instead of the metal-free phthalocyanine manufactured in Example 1 as a carrier-generating substance.
An electrophotographic photoreceptor was produced in the same manner as described above. When the electrophotographic characteristics were measured, the initial surface potential was -800 V, and the charge retention was 87.
% And the half-life exposure amount was 8.6 erg / cm ² .

Example 5 (Production and test of photoreceptor) 1 part of the metal-free phthalocyanine produced in Example 1 in a 100 ml glass pot, 6 parts of a polyester resin (trade name: Byron 200, manufactured by Toyobo Co., Ltd.), and tetrahydrofuran 30
And 40 parts of glass beads having a diameter of 3 mm were charged and shaken and dispersed with a paint conditioner for 2 hours to prepare a photoreceptor coating solution. A photoreceptor coating solution was applied on a PET film on which aluminum was deposited by a bar coater so as to have a dry film thickness of about 20 μm, and dried to prepare a photoreceptor.

The obtained photoreceptor was subjected to an electrostatic copying paper tester EPA-8100.
(Kawaguchi Electric Works) was used to measure the electrophotographic characteristics. The measurement is performed by applying +5.5 kV corona discharge for 3 seconds to positively charge the surface, leaving it in a dark place for 5 seconds, irradiating white light from a tungsten light source, and irradiating energy required to reduce the surface potential to half. Amount, that is, a so-called half-exposure exposure amount. The characteristics of the electrophotographic photoreceptor in this example were such that the initial surface potential was +360 V, the surface potential after dark decay for 5 seconds was +349 V (charge retention 97%), and the half-life exposure amount was 2.1 lux · sec.

Comparative Example 5 (Production and Test of Photoreceptor) In the same manner as in Example 5 except that the metal-free phthalocyanine produced in Comparative Example 2 was used instead of the metal-free phthalocyanine produced in Example 1 as a carrier-generating substance. Thus, an electrophotographic photosensitive member was manufactured. When the electrophotographic characteristics were measured, the initial surface potential was +350 V, the charge retention was 96%, and the half-life exposure amount was 3.9 lux · sec.

(Effects of the Invention) As described above, the use of the metal-free phthalocyanine according to the present invention has high sensitivity not only to white light but also to long-wavelength light, particularly in the oscillation wavelength range of a semiconductor laser. An electrophotographic photoreceptor can be manufactured. Furthermore, the metal-free phthalocyanine of the present invention has excellent sensitivity as a carrier-generating substance, has little variation among production lots in its performance, is easy to produce, and has extremely excellent production stability in performance. The produced electrophotographic photoreceptor has not only excellent characteristics but also a stable effect, that is, a remarkable effect that has not been obtained in the related art.

[Brief description of the drawings]

FIG. 1 is an X-ray diffraction diagram of the metal-free phthalocyanine of the present invention,
FIG. 2 is an X-ray diffraction diagram of the τ-type metal-free phthalocyanine, and FIG.
The figure shows the X-ray diffraction pattern of X-type metal-free phthalocyanine, FIG. 4 shows the X-ray diffraction pattern of metal-free phthalocyanine described in JP-A-60-243089, and FIG. FIG. 3 is an X-ray diffraction diagram of a metal-free phthalocyanine. FIG. 6 is an infrared absorption spectrum of the metal-free phthalocyanine (a), the X-type metal-free phthalocyanine (b), and the metal-free phthalocyanine (c) described in JP-A-62-47054 used in the present invention. .

Claims (3)

(57) [Claims] 1. The Bragg angle (allowable range ± 0.2 degrees) of CuKα to X-rays is 7.4, 9.0, 16.5, 17.2, 22.1, 23.8, 2
It has major diffraction peaks at 7.0 and 28.4 degrees, and has substantially two diffraction peaks at Bragg angles (acceptable range ± 0.2 degrees) of 21 to 25 degrees, and 700 cm in infrared absorption spectrum. ^-1 has four peaks in the range of 760 cm ^-1 from metal-free phthalocyanine, wherein the peak of 732 cm ^-1 is the strongest peak. 2. The method for producing a metal-free phthalocyanine according to claim 1, wherein the α-type metal-free phthalocyanine is dry-milled at 20 to 80 ° C. using a ball mill or a vibration mill. Production method. 3. An electrophotographic photoreceptor comprising the metal-free phthalocyanine according to claim 1.