DE2037459C3 - A method for forming hexagonal crystals of metal-free α-phthalocyanine and using these hexagonal crystals of metal-free α-phthalocyanine - Google Patents

Description

The invention relates to a process for the formation of hexagonal crystals of metal-free alpha-phthalocyanine ranging in size from about 1 to about 75 microns.

Phthalocyanine, also called Tetrabenzotetraazc.porphin and Te'rabenzoporphyrazine is known, can be referred to as a condensation product of four isoindole groups will. Metal-free phthalocyanine has the following structure:

In addition to the metal-free phthalocyanine of the above structure, there are numerous metal derivatives of Phthalocyanine is known in which the two hydrogen atoms in the center of the molecule are replaced by metals of each group of the periodic table are replaced. It is also known that one to sixteen of the peripheral hydrogen atoms in the four benzene rings of the phthalocyanine molecule through halogen atoms and can be replaced by numerous organic and inorganic groups.

Metal-free phthalocyanine is known to exist in at least three polynorphic forms, the alpha-, the

beta and the X shape. The X-form is a newly discovered pclymorphic form of phthalocyanine, the It shows unique electrophotographic properties, for example, in UK patents 11 16 553 and 11 16 554. The different Forms of metal-free phthalocyanine can be easily identified by comparing their X-ray diffraction patterns and / or Infrared spectra can be determined as described in British Patent 1169901.

The alpha form of phthalocyanine has several important properties. For example, it is used commercially for plastics, paints, and printing inks. It is also known that alpha-phthalocyanine can be used alone or together with the X-form of phthalocyanine as a photoconductive material for electrophotography. Furthermore, the alpha form of phthalocyanine can be converted into the X form, for which purpose any suitable milling process, for example ball milling or salt milling, can be used. Alpha-phthalocyanines j _{O also} find use in image formation by particle migration, for example in photoelectrophoresis, described in US Pat. No. 3,384,448 and in the multilayer process.

Will drive at a fotoelektrophoretischen Abbildungsver- _2S variously colored light used absorbent particles that are suspended in a non-conductive TrägerlFlüssigkeit. This suspension is placed between two electrodes, exposed to a potential difference and exposed to an image. When performing these steps, there is selective particle migration in an image-wise distribution that creates a visible image on one or both electrodes. An essential part of the process are the suspended particles, which must be intensely colored and electrically sensitive to light and evidently experience a change in their self-charge polarity when exposed to activating radiation through interaction with one of the electrodes. Colored images are generated because mixtures of two or more differently colored types of particles are used, each of which is only sensitive to light of a certain wavelength or a narrow wavelength band. The particles used must be intensely colored and very sensitive to light.

An imaging method using a multilayer arrangement has already been proposed containing an electrically photosensitive substance between two sheets of paper. In this procedure the image material layer is made by applying an electrically photosensitive image material to a support educated. In one embodiment, the image layer contains a photosensitive material such as e.g. B. alpha-phthalocyanine, dispersed in a tough, soft, non-conductive binder. The coated base is also referred to as a donor sheet. The image layer can be made tough and soft if necessary. The process step of this softening the The image layer is referred to as Aktivitrung and usually takes place by touching the image layer with r> o a swelling agent, a solvent, a partial solvent, or by exposure to heat. the Activation can also be omitted if the image material layer after its formation on the substrate from a Solution or paste enough remaining solution <> s contains medium or is sufficiently viscous that it can be exposed to electromagnetic radiation, for which purpose normally visible light is used, and an electric field in an image-wise distribution can break. After activation, a receiver sheet is applied to the surface of the adhesive layer Then an electric field is generated on this multilayer arrangement while simultaneously an exposure takes place with a light-shadow pattern that corresponds to the image to be reproduced. When the donor sheet is separated from the receiver sheet, the image material layer breaks along the through the Light-shadow pattern defined lines. Part of the image layer is then placed on one of the sheets transferred while the remainder remains on the other sheet, so that a positive image, i.e. H. a duplicate of the Originals that have one sheet of paper and a negative image on the other sheet

In the formation of alpha phthalocyanine for use in a process of the above many difficulties arise. The use of alpha phthalocyanine in particle migration processes places certain requirements on the crystal size of this material. For example the crystals of alpha-phthalocyanine are said to be largely be pure and range in size from about 1 micron to about 75 microns. Become hexagonal crystals of this Size used also results in easier and more complete color separation.

The manufacture of alpha-Phthalocyar.in after known processes, such as those in "Phthalocyanine Compounds" by Moser and Thomas, Rheinhold Publishin Company, pages 104-189, descriptive, results in crystals less than 1 micron in size. Furthermore, the application of the most organic solvents for crystal growth, for example of o-dichlorobenzene or Dimethylformamide, into large crystals of the polymorphic beta form. The ^ -phthalocyanine can be in the «Form can be implemented by dissolving it in 98% sulfuric acid solution and converting the solution into Ice water is precipitated. However, sulfuric acid degrades the phthalocyanine and leads to the formation of Phthalimide, phthalic acid and various nitrogenous compounds that are produced in a particle migration process are undesirable. Furthermore, the -phthalocyanine produced in this way has a particle size of less than 1 micron.

From FR-PS 15 46168 a process for the production of water-soluble nitrogen-containing dyes is known for dry mixing with food, the colorants under special Conditions are precipitated from aqueous solutions and obtained an average crystal length of 40 to 120 μ. However, α-phthalocyanine cannot be obtained or recrystallized in this way.

The object of the invention is to "-phthalocyanine while avoiding the above To produce disadvantages while achieving a particle size that is comparable to that of a particle migration process is applicable. This size should be between about 1 micron and about 75 microns. Furthermore, the end product should be free of sulfuric acid impurities and decomposition products, so it is an improved one photoelectrophoretic imaging method, a multilayer method and a particle migration method with color separation is suitable.

A method of the type mentioned at the outset is designed to solve this problem in such a way that metal-free -phthalocyanine and / or metal-free β- phthalocyanine with a basic

alcoholic solvent is mixed. Here can heating to approximately the reflux temperature also takes place, which favors crystal growth.

Any suitable substituted or unsubstituted metal-free phthalocyanine can be used. These include metal-free -phthalocyanine, metal-free -phthalocyanine or mixtures of these two, however, the best results are achieved with metal-free α-phthalocyanine. When the invention Process is converted ^ -phthalocyanine into «-phthalocyanine.

Any basic alcoholic solvent can be used in the method according to the invention, in particular will give good results with sodium ethoxide, sodium propoxide, potassium propoxide or lithium butoxide achieved, each dissolved in ethanol, propanol or butanol.

The metal-free phthalocyanine should remain in the solvent as long as crystals with the size about 1 micron to about 75 microns can be produced. A preferred time is between approx. 4 and approx. 8 days without heating, shorter times result when heating up to the reflux temperature.

The following examples serve to further illustrate preferred embodiments of the invention. Parts and percentages relate to the weight, unless otherwise stated.

Example I.

Approx. 30 g of metal-free / J-phthalocyanine with a Particle sizes of less than 1 micron are added to a solution that dissolves approx. 30 g of potassium propoxide in approx. Contains 170 ml of propanol. The material will be roughly up to heated to reflux temperature and after a short time hexagonal crystals result from metal-free «-Phthalocyanine, the size of which is between about 1 micron and about 75 microns.

Example II

Example I is repeated, but with metal-free alpha-phthalocyanine instead of the metal-free beta-phthalocyanine is used. The solution is not heated, but left to stand for about 5 days. It result in hexagonal crystals of metal-free alpha-phthalocyanine, their size between approx. 1 micron and about 75 microns.

Example Ellund IV

Example I is repeated, but instead of the metal-free b: ta-phthalocyanine, metal-free alpha-phthalocyanine is used and Example II is repeated with the difference that instead of the alpha form the polymorphic beta form is used. In any case, metal-free crystals result alpha phthalocyanine approximately 1 micron in size up to approx. 75 microns.

Examples V to VII

Example I is repeated three times, the solvent being sodium ethoxide in ethanoi, potassium propoxide is used in propanol and lithium butoxide in butanol. The results agree with them Example I match. In each of the following Examples VIII-X a suspension is used, the same Contains proportions of three colored pigments. It is made by dispersing the pigments in a kerosene fraction formed, with the pigments making up eight percent by weight of the mixture. The mixture can also be referred to as a three-component mixture. The three-component mixtures are tested individually, by applying it as a layer to a NESA glass plate and as in Example I of the US patent 33 84 488 are exposed, with the difference that instead of a black and white slide a Kodachrome slide is used. In this way, a multicolored image is projected onto each plate while the Roller electrode is moved over its surface. One

ίο barrier electrode with baryta paper is used, and the roller has a negative voltage of approx. 2500 volts. The roll is passed over the plate six times, with after each transition, the adhering particles are removed from the barrier electrode. After the six

is transitions is the quality of the on the plate evaluates the existing image with regard to the tint density and the color purity.

Example VIII

The three-substance mixture contains metal-free alpha-phthalocyanine, formed according to Example I ₁ crystal size approx. 1 micron to approx. 75 micron, the yellow pigment "Indofast Yellow Toner", Flavanthron, CI No. 70 600 and the magenta pigment "Watchung

2s Red B ", a barium salt of 1- (4'-methyl-5'-chlorazobenzene-2-sulfonic acid) -2-hydroxy-3-naphthenic acid, C. I. No. 15 865. When exposed in the manner described above, this ternary mixture results in a multicolored image that corresponds to the original image and

ίο a very good color density, especially an excellent one Has color separation.

Example IX

Example VIII is repeated with a ternary mi-} s Schung, the alpha-phthalocyanine, formed according to Example II, crystal size about 1 micron to about 75 microns, the yellow pigment N-2 "(l", 3 "thiazole) -8-13-dioxodinaphtho- (l, 2-2 ', 3') -furan-6-carboxamide and a magenta pigment, namely a quinacridone pigment. As shown in Example VIII excellent tinting and color separation properties.

Example X

Example VIII is repeated with a three-component mixture, the alpha-phthalocyanine, formed according to Example III, crystal size approx. 1 micron to approx. 5 micron, the yellow pigment »Algol Yellow GC«, 1,2,5,6-di (C, C'-diphenyl) -thiazole-anthraquinone, N. I. No. 67 300,

so and "Bonadur Red B", an insolubilized azo dye, C.I. No. 15 865, contains. As in example VIII gives excellent tinting and color separation properties.

Examples XI-XIV

A multilayer arrangement is made as follows: 5 g Sunoco 1290, a microcrystalline Wax with a melting point of 81 ° C are dissolved in 100 ecm of reagent petroleum ether, which is diluted to approx.

50 ⁰ C, and quenched by immersing the container in cold water. In this way, small wax crystals are formed. 5 g of metal-free alpha-phthalocyanine, formed according to Example I (particle size about 1 micron to about 75 microns) are then added to the

i> s wax paste and poured into a grinding vessel of 568 ecm together with 284 ecm of clean porcelain balls. There is then a ball milling in the dark with a period of 3 ^1/2 hours at

70 rpm, and after grinding, 20 ecm of a kerosene fraction are added to the paste. The paste is then applied as a layer under subdued green light onto a Mylar sheet 0.05 mm thick with a wire-wound spreader rod No. 12, which produces a layer thickness of 2.5 microns after drying. The same paste is also applied to three other Mylar sheets, with a spreader stick no. 8 producing a layer thickness of 1.5 microns, a spreading stick no. 24 producing a layer thickness of 5 microns and a spreading stick no. 36 producing a layer thickness of 7.5 microns . Each of these layers is then ^{heated to approx. 60 °} C. in the dark for drying. The donor sheets formed in this way are placed on the tin oxide surface of a NESA glass plate, their layers being exposed. A Mylar film 0.05 mm thick, serving as the receiving sheet, is then placed on the coated surface of each donor sheet. A sheet of black, electrically conductive paper is then placed on the receiver sheet, after which the multilayer arrangement is complete. The receiver sheet is then raised and the phthalocyanine wax layer is activated with a quick stroke of the brush using a wide camel hair brush saturated with petroleum ether. The receiving sheet is then placed back on and a roller slowly guided over the closed multilayer arrangement with slight pressure in order to remove excess petroleum ether. The negative terminal of a DC voltage source of 8000 volts is then connected to the ^ o N ESA layer and to the black, opaque electrode and grounded. When voltage is applied, a light image with a white incandescent lamp is projected from below through the NESA glass plate, for which purpose Wollensak magnifying optics, 90 mm, f 4.5, are used. The exposure level is approx. 0.108 lux, the exposure time approx. 5 seconds. This results in a total energy of 215 lux / sec. After exposure, the receiver sheet is peeled off the assembly, with the voltage still on. The small amount of petroleum ether still present evaporates within about a second after separating the sheets, leaving two excellent images, one of which is a duplicate of the original image on the donor sheet, the other a reverse image of the original image on the receiving sheet. With all four layer thicknesses the images are very good.

ExamplesXV andXV!

Example XI is repeated twice, the metal-free alpha-phthalocyanine from Examples II and III is used. In either case, images of excellent quality result.

Although certain substances and amounts of substance have been mentioned in the preceding examples, you can also other suitable substances can be used with similar results. Further substances can also be used be provided in order to have a synergistic, improving or otherwise beneficial effect on the properties to achieve the image material layer. For example, various dyes, spectral sensitizers, Complex substances and electrical sensitizers such as. B. Lewis acids be provided to to improve imaging upon particle migration.

Claims (14)

Patent claims: 1. Process for the formation of hexagonal crystals of metal-free alpha-i'hthalocyanine with a Size from about 1 to about 75 microns, thereby characterized in that metal-free alpha-phthalocyanine and / or metal-free beta-phthalocyanine mixed with a basic alcoholic solvent. 2. The method according to claim 1, characterized in that that the solvent is mixed with crystals of metal-free alpha-phthalocyanine. 3. The method according to claim 1 or 2, characterized in that a basic alcoholic Solvent is used, its basic properties by one or more of the substances Sodium ethoxide, sodium propoxide, potassium propoxide and lithium butoxide are produced. 4. The method according to any one of claims] to 3, characterized in that a solvent with an alcohol content from one or more of the substances ethanol, propanol and butanol is used will. 5. The method according to any one of claims 1 to 4, characterized in that the mixture of Phthalocyanine and solvent is stored for approximately 4 to approximately 8 days. 6. The method according to any one of claims 1 to 4, characterized in that the mixture of Phthalocyanine and solvent is stored for approximately 5 to approximately 8 days. 7. Process according to one of claims 1 to 4, characterized in that the mixture of Phthalocyanine and solvent is heated to about reflux temperature. 8. The method according to claim 2, characterized in that crystals of metal-free alpha-phthalocyanine which have a particle size of less than 1 micron can be used. 9. Metal-free alpha-phthalocyanine in the form of hexagonal crystals, produced according to the process according to any one of claims 1 to 8. 10. Use a according to the procedure according to one of claims 1 to 8 formed phthalocyanine in the electrophoretic image generation, characterized in that an image layer containing the phthalocyanine is between at least two electrodes, one of which is at least partially transparent, an electric field and at the same time through the transparent electrode through an image-wise distributed activating electromagnetic radiation is exposed, whereby an image on at least one of the electrodes is generated from migrated particles. 11. Use according to claim 10, characterized in that the image suspension is a Number of finely divided particles of at least two different colors in a non-conductive one Carrier liquid contains the particles of each color from a photosensitive pigment material exist whose main light absorption band essentially coincides with its main sensitivity band collapses and that the particles of a color from the metal-free alpha-phthalocyanine exist. 12. Use according to claim II, characterized characterized in that the image suspension rnagen- tan particles that are mainly sensitive to green light, yellow particles that are mainly are sensitive to blue light and cyan particles are primarily sensitive to red Light sensitive, contains, and that the cyan colored particles from the polymorphic alpha form of the metal-free phthalocyanine. 13. Use a according to the procedure according to one of claims 1 to 8 formed phthalocyanines for image formation in an image material layer, characterized in that a tough-soft, electrically photosensitive image material layer between a donor sheet and a receiver sheet containing the metal-free alpha-phthalocyanine contains that an electric field and an image-wise distributed one on the image material layer activating electromagnetic radiation is brought into action and that the receiving sheet from the donor sheet with applied electrical Field is separated, whereby the image material layer breaks in image-wise distribution and a Positive image attached to one of the sheets, a negative image attached to the other sheet. 14. Use according to claim 13, characterized in that at least the dispenser sheet and / or the receiving sheet is at least partially transparent to activating electromagnetic radiation is.