FI57320B - FOER FARING FRAMSTAELLNING AV DIAZOTYPKOPIOR - Google Patents

Description

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Netherlands-Nederlanderna (NL) 7207099 (71) Oce-van der Grinten N.V., St. Urbanusweg 102, Venlo, Netherlands-Nederlanderna (NL) (72) Johannes Petrus BSmers, Grubbenvorst, Gerardus Jacobus Vosbeek,

Yelden, Netherlands-Nederländema (NL) (7 ^) Berggren Oy Ab (5 * 0 Method for the preparation of azotypes Utopias - Förfarande for framställning av diazotypkopior

The invention relates to a method of making copies, in which a diazo-type substance consisting of a substrate coated with a diazo layer is developed after image exposure by uniformly applying a buffered aqueous solution of an azo coupling component to the diazo layer.

In the diazotype method, as explained in detail in J. Kosar's book "Light Sensitive Systems", published by John Wiley and Sons Inc., New York / London / Sydney (1965) on pages 19 et seq., Two different systems are well known.

The dry or ammonia process uses a diazotype substance in which the photosensitive diazonium compound and the azo coupling component are present in the same layer. This layer also contains an acid stabilizer. After image exposure, this material is generated by the action of moist ammonia gas, whereby the diazonium compound remaining in the parts in the unexposed tower is coupled to the azo coupling component to form an azo dye. An unpleasant and pungent odor of ammonia must be considered a serious drawback in this method. In order to prevent too much ammonia from escaping into the work area, the copier used in this method must be equipped with 2 57320 exhaust systems. Nevertheless, copies always smell of ammonia for a long time. The half-process uses a diazotypic substance in which the photosensitive layer contains only the diazonium compound with or without stabilizers and other additives. The copy is developed by applying a uniformly thin layer of a buffered aqueous solution of the azo coupling component to the diazo layer.

In practice, the amount of the layered azo coupling component solution is 7-8 cm / m per side. This amount is necessary to make the developer evenly distributed and to achieve rapid and complete development with conventional development equipment and slides of warfare agents. Generally, a virtually equal amount of developer is also applied to the opposite side of the copy medium to prevent the paper from curling.

A copy developed in this way contains quite a lot of moisture. In fact, a few copies can be air-dried, but if a large number of copies have to be made, a drying device is necessary. Such a drying device requires a large heating capacity, especially in copiers operating at high speeds. Besides, it takes quite a while for the dryer to reach the desired drying temperature. This causes an unwanted waiting time before the copier can be used. For this reason, efforts have long been made to find a development method which could produce dry or virtually dry copies but which would not have the disadvantages of the ammonia method.

For this purpose, U.S. Patent No. 1,841,653 proposes the application of developing fluid by means of press rolls. With the help of two rubber-coated rollers, an excess developer is applied, which the same rollers squeeze out again the next moment. According to this patent publication, the copy thus obtained is practically dry. In fact, however, the developer has completely penetrated the copier, as a result of which this contains a considerable amount of moisture. Therefore, a drying device is necessary for fast-acting copiers.

Another solution is proposed in British Patent Specification 1 1 ^ 3 702. According to the method described in this patent publication, a two-component diazotype substance is used as in the ammonia process. Instead, the development is carried out by applying a controlled amount of up to 3 cm / m of an alkaline liquid containing at least 20% of an aliphatic amine. Copies obtained in this way are immediately dry but feel slightly greasy. A further disadvantage is the relatively slow development due to the fact that slow-coupling diazonium compounds are generally used in the two-component material used and probably also because the viscosity developer penetrates relatively slowly through the material to be developed.

A method for making copies has now been developed which provides dry copies immediately and does not have the disadvantages associated with the above methods. According to the invention, diazotype copies are prepared by exposing, as shown, a diazo compound containing a diazo compound in a photosensitive surface layer having a thickness not exceeding 8 μm which in vitro binds more actively than 4-diazo-2-chloro-N, N-diethylaniline and developing it by exposing the photosensitive side of the material to an aqueous developer solution in an amount of 1.5 to 4.5 cm / m, buffered to a pH of 5.5 to 7.0 and containing 0.1 to 0.6 g of an azo coupling compound, and 1-3 g equivalents of buffer salt per liter.

Copies developed in this way immediately feel dry because the small amount of moisture that is added to them evaporates very quickly and by itself, which is why even high-speed copiers do not require a dryer.

The process of the invention uses an aqueous, weakly acidic, buffered solution of one or more azo coupling components, buffered to pH 5.5-7.0 and containing 0.6 g of the azo coupling component and 1-3 g equivalents of a buffer salt. per liter. The developer solution preferably contains phloroglucinol as an azo coupling component. In addition to or instead of phloroglucinol, other azo coupling components known from diazotype developer solutions, for example resorcinol, can be used. The total amount of azo coupling component in the developer solution should be 0.1-0.6 g-moles per liter.

As the buffer salt, the developer solution may contain buffer salts known per se from aqueous diazotype developer solutions. Suitable buffer salts include succinic, glutaric, adipic, g-methyladipic, maleic, malonic and citric acid alkali metal, magnesium and ammonium salts.

Examples of suitable buffer salts are given in GB Patent 857,836 and FR Patent 1,347,703. Of course, mixtures of buffer salts can be used in the developers for use in the process according to the invention. The total amount of buffer salt in the developer is 1-3 g equivalents per liter.

4,57320

The developer solution may also contain anti-yellowing agents, antioxidants, growth accelerators and wetting agents known per se.

The process according to the invention uses a diazotype material which, in a photosensitive surface layer with an average thickness not exceeding 8 [mu] m, contains a diazo compound which binds more actively in vitro than 4-diazo-2-chloro-N, N-diethylaniline.

With such diazo compounds, the development proceeds quickly and completely when the above-mentioned neutral / weakly acidic developers are used.

Therefore, the diazo layer primarily contains a diazonium compound having a higher in vitro coupling activity than p-diazo-o-chloro-diethylaniline. The coupling activity of diazo compounds is measured as described in British Patent Publication 957,836.

Examples of such fast coupling diazonium compounds are disclosed, for example, in the aforementioned patents and in British Patent Publication 957,838. Certain compounds are preferred. These include: 1-diazo-4-benzoylamino-2,5-dibutoxy-benzene, 1-diazo-2,5-diethoxy-4- (4'-methoxy) phenyl-benzene, 1-diazo-2,5- Dimethoxy-4- (4 * -methyl) phenylthio-benzene, 1-diazo-2,5-diethoxy-4- (4 * -methyl) phenylthio-benzene, 1-diazo-4-dimethylamino-3- (4'-chloro) ) phenoxy-6-chloro-benzene, 1-diazo-4-dimethylamino-3- (N'-chloro) phenoxy-2-chloro-benzene, 1-diazo-2- (ethoxycarbonyl) (benzyl) amino-4- ( methyl) (cyclohexyl) amino-3-methoxybenzene, 1-diazo-4-benzoylamino-2- (ethoxycarbonyl) (methyl) amino-5-methoxybenzene, 1-diazo-2- (ethoxycarbonyl) (methyl) amino-5-methoxy-4- (4'-methyl) phenylthiobenzene.

For the reasons mentioned below, the diazonium compounds are preferably used as water-soluble salts, e.g. hydrogen sulphate or chloride. The diazon layer may contain more than one diazonium compound. In addition, conventional additives such as acids and stabilizers may be present, e.g., the sodium salt of 1,3,6-naphthalene trisulfonic acid, reducing agents, thiourea, etc.

5,57320

The film layers described in British Patent Publication No. 957,836, in which the diazonium compound is present in a hydrophilic film layer having a thickness of about 4.5, are particularly suitable for development by the process of the invention.

In opaque materials used in the semi-wet process, which are based on paper that may be pre-coated, some of the diazonium compounds are located much deeper in the material »This is because the diazonium compound is added as a diazo solution in an amount of about 10-15 cnr / m. This may be the reason why the diazonium compound penetrates deep into the substance.

Since in the method according to the invention the development is achieved with an amount of developer which is only 1.5-4.5 cm / m, the azo coupling component cannot penetrate so deep into the substance. The consequence of this is that development does not become perfect. Generally, the diazonium compound is converted to the azo dye in an amount not to exceed about 70%.

This problem can be solved by first coating the paper with a hydrophobic barrier layer and depositing on it a hydrophilic layer of the desired thickness. The diazonium compound may be added simultaneously with the hydrophilic layer or later. In this way, the penetration of the diazonium compound too deep is prevented. The composition of the substance then resembles the film substances »described in British Patent Publication 957,836.

However, it has been found that penetration of the diazonium compound too deep can also be prevented by sensitizing the substance with a smaller amount of a diazole solution containing suitably more diazo compound. A suitable amount is e.g. 2-8 cm / m, preferably about 3 cm / m. In this way, the diazonium compound penetrates approximately as deeply and in the same manner as the azo coupling component. When a substance sensitized in this way is used, the development becomes practically complete (95-100%).

To illustrate the effect of this sensitization method, a series of diazotype papers sensitized in a known manner at 10-15 cnr per 11 m and a series of diazo-type papers sensitized according to the invention per 3 cnr per mole were developed with the developing solution described in Example 1. Pieces of the developed material were cut so that the cross section of the azo dye layer could be viewed under a microscope. The thickness of the dye layer turned out to vary greatly from place to place. Therefore, the layer thickness was measured at a large number of locations, and the arithmetic mean was calculated from the results of these measurements. This average value of 6,57320 is reported below as the average maximum layer thickness. For diazotype papers that were sensitized 10-13 3 2 ...

cm per 11 m, the average maximum layer thickness turned out to be about 9-12. For diazotype papers that were 3 2 ...

sensitized according to the invention per 3 cm, the average layer thickness was 5.5-7.5 μm.

The average maximum layer thickness of the diazotype papers used according to the invention should not exceed 8 [mu] m, in particular not more than 7 [mu] m.

If the diazo layer is deposited directly on the paper, the surface texture of the paper may appear in the copy as an uneven distribution of the azo dye. This can be avoided by providing the paper with a pre-coating as is already known. This precoat generally consists of an inorganic pigment such as silica, alumina or metal silicate, or an inorganic pigment such as starch, rice starch and the like, in a binder such as casein, polyvinyl alcohol, polyvinyl acetate.

Surprisingly, it has been found that even substances in which the diazonium compound is present in the hydrophilic membrane layer are sensitive to diazonium salt solution instead of 8 to 15 cnr per m instead of 8 to 15 cfr, as is customary for these substances. , has a beneficial effect on the rate of development and the completeness of development with the diazotypic substance thus prepared.

The cross-sections of the developed substance show that even in this case the diazonium compound is closer to the surface if the substance is sensitized by 2-6 cm per m. The azo coupling component is thus able to reach the diazonium compound in a simpler way.

The amount of developer that spreads to the diazo layer during development depends on the surface structure, hydrophilicity, and porosity of the diazotypic material to be developed. The smoother layer absorbs less developer than the coarser layer.

The amount deposited on lacquered materials with a synthetic substrate, for example polyester foil, or transparent paper, coated with a hydrophilic film layer and optionally a hydrophobic interlayer, e.g. a surface-saponified cellulose acetate layer, is about 1.5-3, 0 cm / m. These films contain more diazonium compound per unit area than diazotype paper. For the complete development of these substances, a certain minimum amount must be used by the developer. If the device used to develop these films is set to t 57320 to deliver the correct amount of deposition, the amount of deposition on the paper will be higher, which means that an excess of the azo coupling component will be deposited on the diazotype paper.

Thus, for ordinary, opaque, paper-based materials, with or without a precoat, the amount of developer to be deposited is 2.5 to 2.5 cm / m, preferably 2.5 to 3.5 cm / m. m.

The above minimum values are due to the requirement that the developer must be able to apply evenly to the diazo layer so that the entire surface is wetted. The upper limit values are due to the requirement that the substance must feel dry when it leaves the developing device.

Although various devices have been described in the literature with which such a small amount of liquid can be uniformly applied to the surface, the best results are obtained by the method according to the invention using the device described below, which means that all the above substances can be used well and the developer deposition becomes smooth and constant.

This device is shown schematically in the accompanying drawing. In the drawing, reference numeral 1 denotes a dosing roll, the surface of which is profiled and which is partially embedded in the developer 3. The profiling can be carried out by forming a helical groove along the entire length of the roll. Reference numeral 2 denotes a deposition roller. The surface is flexible, non-porous, and suitably hard, the hardness usually being 10-50 °, preferably 25-35 ° Shore A. The number * 4 denotes a compression strip of which at least the part in contact with the deposition roll is a flexible material, e.g. Teflon. To prevent the formation of a liquid splash and the wetting of the back side of the copy, the edge of the press strip is preferably provided with U-shaped cuts.

For removing the press strip from contact with the deposition roll when there is no copy between the strip and the roll, means may be provided.

Instead of a press strip, it is also possible to use a press roll with protrusions on the surface which prevent the press roll from getting wet and thus also the wetting of the back side of the substance to be developed.

Reference numerals 5 and 6 denote a diazotype substance inlet and an outlet, respectively. 7 denotes the copying agent to be developed. 8 is a housing for preventing water from evaporating from the developer.

The copy to be developed is fed forward between the deposition roll 2 and the pressing strip 4 with the photosensitive side facing down.

8 57320

When the device is running, the dosing roller 1 hands the developer to the layering roller 2. The layering roller 2 takes a part of the developer to its surface and transfers it to the copy to be developed. This takes 2 from the roll, which depends on e.g. the substance to be developed. The amount of developer to be deposited on a particular material, e.g. paper, depends on e.g. the surface structure of the dosing roll 1, the hardness and hydrophilicity of the deposition roll 2, the pressure between the deposition roll 2 and the dosing roll 1, and the pressure between the pressing strip 4 and the deposition roll 2. Therefore, all of these quantities must be fitted to their terns, and many suitable combinations are possible.

Thus, e.g. a developing device in which the metering roller is provided with a groove having a depth of 25 μm and a pitch of 0.3 mm. The cross section of the groove is triangular. The top width is 50 μm. The surface of the deposition roll is made of polished rubber with a hardness of 25 ° Shore A. The line pressure between the metering roll and the deposition roll is 7 g / mm and the line pressure between the press strip and the deposition roll is 4 g / mm.

With this developing device, a deposition rate of the developer is obtained, which remains constant up to a flow rate of 20 m / min 3 2 of the material to be developed, namely between 3.5-4 enr / m on paper, and between 1.5-2 cm ^ / m ^ on the film. . In general, the pressure between the press strip and the deposition roll should be 2-10 g / mm and preferably 3-5 g / mm. The pressure must exceed a certain minimum value in order to achieve good and even humidification. If the pressure is too high, the deposition rate of the developer on the film material will be too low. The deposition roll must be coated with a material having a hardness of not more than 50 ° Shore A and preferably 25-35 ° Shore A. This is necessary to achieve uniform wetting at different thicknesses of the material to be developed and tolerance ranges of the press strip and rolls used. The pressure between the deposition roll 2 and the metering roll 1 is 3-9 g / mm, preferably 5.5-7.5 g / mm. The surface structure of the dosing roller, i.e. the overall cross-section of the holes obtained per millimeter must finally be chosen in such a way that the pressures used achieve the desired amount of deposition of the developer. This structure must not be too rough, as this would leave the structure more or less visible in the final copy, as the developer would then no longer be able to be applied evenly enough on the deposition roll. In the above example, the total cross-sectional area of the groove as seen in the longitudinal section 2 of the roll is about 2000 μm / mm.

In the method according to the invention, the developer is preferably deposited only on the diazo layer. For this reason, diazotype paper 9 57320 tends to curve backwards, i. so that the photosensitive side is facing out. This curvature phenomenon disappears in a short time. If desired, this curvature phenomenon can be reduced or its duration can be shortened. For example, the paper can be made more difficult to access by water by pre-coating it with a substance which forms a more or less barrier layer on the surface of the paper. In this way, too deep penetration of the diazonium compound is also prevented.

The invention is illustrated by the following examples. Example 1

The base paper of the diazotype process was precoated on the other side in a known manner from a material having the following composition: 10 g of crystalline silica having a particle size of 5 μm, 6 cm 50 weight-5 £ polyvinyl acetate emulsion, to which water was added until the total amount was 100 cm 3.

Coating was performed by applying this mixture to 3 3 15 cm / m paper and drying it. The precoated surface was then sensitized by applying a 2 cnr / m 0.14 molar diazohydrate solution to the surface and drying. A mixture of two diazonium compounds was used in the diazole solution, namely 4-dimethylamino-3- (4'-chloro) phenoxy-6-chloro-benzene-diazonium hydrogen sulfate and 2,5-diethoxy-4- (4'-methyl) phenylthio-benzene-diazonium hydrogen sulfate by weight. - in a ratio of 2: 1. The diazotype material thus obtained was exposed under a transparent original and then developed by uniformly applying to the diazone layer a 5 2 3 cnr / m solution having the following composition using the developing device shown in the drawing: 260 g of dipotassium succinate (calculated anhydrous) 25 g of phloroglucinol 2aq.

6 g resorcinol 1 g Aerosol AY (wetting agent from American Cyanamid Co.) 1000 cm 2 water.

The pH of this solution was adjusted to 6.8 by the addition of succinic acid. The solution contained 0.9 moles of succinate and 0.2 moles of azocyte field component per liter.

Immediately after development, the copy felt dry and had a strongly black image containing hardly any unreacted diazonium compound.

Example 2

A layer of about 20 g / m cellulose acetate deposited on natural translucent paper having a basis weight of about 2 2 80 g / m 2 was hydrolyzed from the surface to a depth of about 5 μm by treating it with a KOH solution in a mixture of water and 10 57320 methanol. The chemicals used for the hydrolysis were removed by washing with water, and drying, after which the paper was sensitized by uniformly applying 3 cm / m of 0.35 molar diazonium salt solution to the hydrolyzed side. A similar result can be obtained by depositing the diazole solution in excess and removing it again after about 1 second, e.g., high-pressure air knives.

As the diazonium salt, n-benzoylamino-2- (ethoxycarbonyl) (methyl) amino-5'-methoxy-benzene-diazonium hydrogen sulfate was used. The diazotype material thus obtained was image exposed and developed as described in Example 1. The deposition rate of the developer was 2.5 cm3 / m. The copy thus obtained immediately felt dry and had a strongly purple / brown image with very good UV absorption against a bright background.

Example 3 2

The polyester foil was provided with a 10 g / m coating layer consisting of cellulose acetate and non-crystalline silica in a weight ratio of 3: 1. This layer was saponified on its surface as described in Example 2. The medium thus obtained was sensitized in the same manner as described in Example 2. The copying medium thus obtained was image-exposed and developed with the apparatus shown in the drawing by applying the 2 cm / m developer solution described in Example 1 to the diazo layer. The results obtained correspond to those obtained in Example 2.

Claims (6)

57320 A process for preparing diazotype copies, characterized in that a diazotypic material comprising a diazo compound in a photosensitive surface layer having a thickness not exceeding 8 μm which binds more actively in vitro than 4-diazo-2-chloro-N, N-diethylaniline, is exposed as shown and then developed by exposing its photosensitive side to an aqueous developer solution of 1.5-4.5 cm / m, buffered to pH 5.5-7.0 and containing 0.1- 0.6 g moles of azo coupling compound and 1-3 g equivalents of buffer salt per liter. A method according to claim 1, characterized in that the photosensitive layer of the diazotype material is formed by uniformly applying an aqueous diazo compound solution of 2 to 8 cm / m to the surface of the support. Process according to Claim 2, characterized in that the aqueous solution of the diazo compound contains 0.05 to 0.6 g of mole of the diazo compound per liter. A method according to claim 2, characterized in that the carrier is a paper with or without a pre-coating layer containing a filler and a binder. Process according to Claim 1, characterized in that the developer solution contains phloroglucinol as an azo-coupling component. Process according to Claim 1, characterized in that the developer solution comprises an alkali metal, magnesium or ammonium salt of succinic, glutaric, adipic, g-methyladipic, maleic, malonic or citric acid as a buffer salt.