DE2162296A1 - Use of organic pigments in photoelectrophoretic imaging - Google Patents

Description

Use of organic pigments in photoelectrophoric imaging. '- - · - .. "- V _'-'; - ■

I.

It is known that one can use electrophoretic means can produce single and multi-colored reproductions by using photoconductive organic pigments. This system makes use of photoconductive particles and is described, for example, in U.S. Patents No. 3 ^ 84 565, 3 38 ^ 566 and 3 385 48θ · described. In one Such imaging systems are differently colored, light absorbing particles in a non-conductive

■. · ORIGINAL INSPECTED

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suspended liquid carrier. The suspension is placed between electrodes, whereupon a voltage is applied and irradiated with an image. This is followed by migration of dye particles in the electric Field an image on one or both electrodes.

An essential component of the system are the suspended particles, which are electrically "photosensitive" have to. These particles obviously suffer when exposed to an activating electromagnetic Radiation causes a charge change, through interaction with one of the electrodes. In a monochromatic System uses particles of a single color, producing a single-colored image, which is equivalent to a usual black and white picture. In a poiychromatic system, the images are in Natural color created as mixtures of particles of two or more different colors, each are sensitive to light of a specific wavelength or a narrow range of wavelengths will.

So far only a few pigments are known, polygamy the high ones The requirements of electrophoretic reproduction technology are sufficient. The dyes in question must be namely characterized by the following properties:

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pure hue, high color strength and lightfastness, insolubility in water and organic solvents and strong photosensitivity. It is also important that the maximum of the photosensitivity as possible in the same wave range as the maximum of the light absorption lies. The dyes must also be sufficiently transparent so that when three are stacked on top of each other Toning creates an intense, deep black.

It has now been found that excellent results can be obtained if you use the following dyes: ------ 4, V-Diamino-ljl'-dianthraehinonyl, 'as well as

Naphtofurandione of the formula. .

COl] H-H-IIHCO

wherein R is an arylene radical, or the quinophthalones of the formula

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in which R is an arylene radical, X and Y are hydrogen or halogen atoms, alkyl or alkoxy groups, or in which X and Y can form a benzene ring together with two adjacent carbon atoms of the basic structure, or phthalimidopyrazolones
the formula

O = C

C-COlJH-H-IIHGO-a

C = O

wherein R is an arylene radical, X and Y _{1 are} hydrogen or halogen atoms, alkoxy, carbonamide or nitro groups and R ^
mean a benzene residue.

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From the series of the naphtofurandiones are in particular the dyes of the formula

T2

COHH-

- ¹ 2

Where Xg and Y »mean chlorine atoms or alkyl groups or the dye of the formula

COMH -

mentioned. The production of these dyes is described in German patent specification 1 "209 683 (Case 4905),

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From the series of quinophthalone dyes, in particular those of the formula are mentioned

- ¹ 2

mentioned, where X and Y are hydrogen or halogen atoms, alkyl or alkoxy groups and Z .. a chlorine atom or an alkoxy group mean. The preparation of these dyes is described in German Patent 1,279,258 (Case 5 ^ 91).

Finally, from the series of phthalimidopyrazolones, in particular those of the formula

com

or

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_. 7 -

. Z

C-CONH-

mentioned, where in the given formulas X ₁ and Y. hydrogen or halogen atoms, nitro or alkoxy groups, X-. and Y, Z ₂ and Z are hydrogen or halogen atoms, alkyl or alkoxy groups. The preparation of these dyes is described in the Swiss patent application G.No. 13260/69 (Case 6850).

The dyes are preferably present in finely divided form, wherein the average particle size below 10 μ zweekmässig and advantageously between 0.1 and 5 m. It is advantageous if the particles are of a uniform size.

The toners suitably contain a binder which fixes the pigment particles on the final image carrier enables. The specific resistance of the binding agent should be higher than 10 ohm cm, two-way higher than

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10 ohm cm. Natural, semi-synthetic or synthetic resins such as Abietic acid esters, tetrahydroabietic acid esters, cellulose esters, cellulose ethers, chlorinated rubber, vinyl resins, such as e.g. polyvinyl chloride, polyvinyl acetate,! copolymers of vinyl chloride and vinyl acetate, polyvinyl acetate, polyvinyl alcohols, Polyvinyl ether, polyvinyl carbazole, polyisobutylene, polybutadiene, polyacrylic or polymethacrylic ester, Polystyrene, polyacrylonitrile or silicone resins. Examples from the series of condensation resins include: Phenol-formaldehyde resins, urea-formaldehyde resins, Melamine-formaldehyde resins, aldehyde or ketone resins, polyamides, Polyurethanes or epoxy resins. The proportion of binder in the toner is expediently between 10 and 60 #. It proves to be advantageous, for example when grinding or kneading the toner with the binder as possible inninge to achieve mixing of the two. At the same time, when using a crude pigment, the desired Reduction of the particle size can be achieved.

The use of the dyes according to the invention in photoelectrophoretic Imaging systems will be understood from the following statements with reference to the appended Drawing showing an example of such a system.

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From the drawing a transparent electrode 1 can be seen, which in this case consists of a layer of an optically transparent glass 2, with a thin optically transparent layer 3 ^a us tin oxide is covered with a layer. This material is commercially available under the name "NESA glass". This electrode is hereinafter referred to as "injector electrode". A thin layer 4 of finely divided, light-sensitive particles, dispersed in an insulating liquid carrier, is coated on the surface of the injection electrode 1. According to the invention, the term "photosensitive" is to be understood as meaning the property of a particle that, once it has been attracted by the injection electrode, it migrates away from the electrode under the influence of an applied electric field when irradiated with actinic electromagnetic radiation. A more detailed theoretical explanation of the mechanism likely to take place can be found in US Patents 3,384,565, 3,384,566 "and 3,385,488. The liquid suspension

4 may also contain a sensitizer and / or a binder for the pigment particles, wherein these agents are at least partially soluble in the suspension or carrier liquid, as will be explained below will be set out in more detail. Adjacent to the liquid

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Suspension there is a second electrode .5., Hereinafter referred to as the "blocking electrode". This electrode is connected to one side of the voltage source through a switch 7. The opposite Side of the voltage source, 6 is with the injection electrode

1 · connected so that if the switch 7 is closed is an electric field across the liquid suspension

4. is applied between electrodes 1 and 5. A projector made from a source of light 8, a dispositive

9i and a lens 10 ^ irradiate the dispersion 4 .: with a light image of the slide 9 to be reproduced. The electrode 5 is _ν in the form of a roller having a conductive zentralen'Kern 11 mit'der voltage source _V is connected 6 "is formed. .The core with a layer of a blocking electrode material 12, which is to act baryta The pigment suspension is irradiated with the image to be reproduced, a voltage being applied across the blocking and injector electrode by closing the switch (7. The roller 5 is moved over the upper surface of the injection electrode 1 ". when the switch 7 is closed The exposure to light causes exposed pigment particles originally attracted to the electrode; 1 to migrate through the liquid

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and stick to the surface of the blocking electrode, leaving behind a pigment image on the injector electrode surface that is a duplicate of the slide is. After the irradiation, the relatively volatile carrier liquid evaporates, leaving the pigment image behind. This pigment image can then be fixed in place, for example by applying a Coating layer on the upper surface or by means of a dissolved binding material in the carrier liquid, such as paraffin wax. It can also be another A suitable "binder can be used which will come out of solution as the carrier liquid evaporates. Approx j5 - 6 percent by weight of the paraffin binder in the Carriers give good results. The carrier liquid itself can be a liquid paraffin wax or another be a suitable binder. According to another embodiment, the pigment image that is on the. Injector electrode remains behind, transferred to another surface and fixed on this. As below will be explained in more detail, this system can produce either monochromatic or polychromatic images, depending on the type as well as depending on the number of pigments suspended in the carrier liquid are, as well as depending on the color of the light with which this suspension is irradiated when carrying out the process will.

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Any suitable isolation fluid can be used as a carrier for the pigment particles in the system. Typical carrier fluids are decane, dodecane, N-tetradecane, paraffin, diene wax or other thermoplastic materials, Sohio Odorless Solvent (a kerosene fraction marketed by the Standard Oil Company, Ohio) and Isopar-E (a branched chain saturated aliphatic hydrocarbon marketed by Esso Oil Company, New Jersey). Good quality images are obtained at voltages between 300 and 5000 volts applied using the apparatus shown in the accompanying drawing. The proportion of pigment in the solvent is expediently 2 - 10 %. The addition of smaller amounts, for example 0.5-5 mol- #, of electron donors or acceptors to the suspensions has a marked improvement in the photosensitivity of the

System.

In a monochromatic system, particles of the same composition are dispersed in the carrier liquid and irradiated with a black and white image. A single color is obtained, and accordingly a usual black and white picture. In a polychromatic system, this is how the particles become selected that the particles with different colors on it

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the different wavelengths in the visible spectrum address according to their main absorption bands. ■ Furthermore, the pigments should be selected in such a way that their spectral response curves do not essentially differ overlap so that a color separation and a sub-. attractive multicolor image generation is possible. In one Typical multicolor system should be the particle dispersion blue-green colored particles, which are mainly opposed red light, purple colored particles that are primarily sensitive to green light, as well contain yellow colored particles that are primarily sensitive to blue light. When mixing in one Carrier fluid, these particles create a black-looking appearance Liquid. If one or more of these particles migrates from the electrode 11 in the direction of the upper one Electrode, particles are left behind that produce a color equivalent to the color of the incident light is. For example, irradiation with red light has the consequence that the blue-green colored pigments migrate, leaving the purple and yellow pigments behind. The combination of these colors results in a red finished picture. In the same way, by removing yellow and purple, respectively, blue and green colors colored pigments reproduced. If white light hits the mixture, all pigments migrate, so that transparent substrate remains. If there is no irradiation

lung, then all the pigments remain, which together form one result in black color. This is an ideal method of subtractive color generation because the particles do not each consist only of a single component, but also have the double function of an image colorant and of a photosensitive medium.

The dyes according to the invention are outstandingly suitable in a single or multi-color electrophoresis imaging system. Their good spectral response as well as their high photosensitivity make the formation denser as well as brilliant images.

The following examples illustrate the invention. The part- Unless otherwise stated, percentages relate to weight. These examples illustrate several Embodiments of the electrophoretic imaging process without, however, the invention being directed thereto restrict.

The following examples are carried out in a device which corresponds to the type which is explained by the accompanying drawing. The imaging mix 4 is applied to a NESA glass substrate. Because of this The irradiation takes place through the glass. The N'ESA glass surface is in series with a switch, a voltage source and the conductive core of a roller, which has an over-

2ΑΒβ? _β / η _η »η. OBiQINAL, NSPECTED

train made of barite paper on its surface, switched. The roller is approximately 6j5 mm (2/2 inches) in diameter and is moved across the platen surface at a speed of approximately 1.45 cm per second. The plate used has a size of about 19.3 cm (3 square inches) and is irradiated with a light intensity of 80000 puss candles, measured on the non-coated NESA glass surface. The size of the applied voltage is 2500 volts. The irradiation takes place with a 3200.K lamp through a neutral, dense wedge filter to measure the sensitivity of the suspensions to white light as well as through Wratten-Pilter 29, 6 "1 and 4? B, which are each brought in front of the light source to measure the sensitivity of the suspensions to red, green and blue light in separate tests The dyes according to the invention are also suitable for other photoelectrophoretic imaging processes, for example, for that described in the Swiss priority application Ges.

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example 1

10 g of 4,4'-diamino-1,1'-dianthraquinononyl with an average particle size of at most 1 μ are suspended in 90 g of Isopar E, a saturated aliphatic hydrocarbon, available from ESSO Standard. The dough obtained is diluted as it is or with further Isopar E, used for the process described above. Brilliant, red images of excellent transparency and lightfastness are obtained.

Example 2

The procedure is as in Example 1, but used as a toner the dyes of the formula

COiIH-

or

COHH-

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OH

COKH

■ dl

H-

Cl

oc σ = a

H OC

-G-CONH-

or

HQOO ft / noon

OC C = C C CONH

^HO = C 1

Cl

2.

in this way, brilliant, yellow images with high lightfastnesses are obtained.

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Claims (1)

Claims ..) Use of 4, V-diamino-1,1'-dianthraquinonyl Naphtofurandiones of the formula " COHH- H - KHCO wherein R is an arylene radical, quinophthalones of the formula COiTH-R-IIHO wherein R is an arylene radical, X and Y are hydrogen or halogen atoms, Alkyl or alkoxy group η, or in which "X and Y can form a benzene ring together with two adjacent carbon atoms of the basic body, or phthalimidopyrazolones the formula ^ 09826/0990 O = G C = O wherein R is an arylene radical, X ₁ and Y _{1 are} hydrogen or halogen atoms, alkoxy, carbonainide or nitro groups and R ₁ mean a benzene residue in the photoelectrophoretic Image generation. . Use according to claim 1 of a naphthofurandione formula COSH- • - ¹ 2 where X _? and Y ^ represent chlorine atoms or alkyl groups. 209826/0990 3. Use according to claim 1 of naphtofurandione the formula 4. Use according to claim 1 of a quinophthalone of the formula - ¹ 2 209826/0990 wherein X and Y are hydrogen or halogen atoms, alkyl or Alkoxy groups and Z represent a chlorine atom or an alkoxy group. 5. Use according to claim 1 of a phthalimidopyrazolone the formula wherein X, and Y- hydrogen or halogen atoms, nitro or alkoxy groups, X, Y-., Z _g and Z are hydrogen or halogen atoms, alkyl or alkoxy groups. 6th Use according to claim 1 of a phthalimidopyrazolone of the formula 209826/0990 C-COMt wherein X. and Y _{1 are} hydrogen or halogen atoms, nitro or alkoxy groups, X_ ,, Υ -, - and Z are hydrogen or halogen atoms, alkyl or alkoxy groups. 7. Use according to claims 1 to ¹ J, characterized in that the pigments have a particle size of 0.1 to 5 M. 209826/0990 L e e γ s e