DE4429741C1 - 1-component diazo blueprint material - Google Patents

Description

The invention is directed to a 1-component diazo blueprint material for the Semi-dry process with on a flat carrier material on one or photosensitive recording layer arranged on both surfaces, the after imagewise exposure to UV light using a one Aqueous liquid developer containing coupling component in semi-dry or thin film process is developed.

Conventional 1-component diazo blueprint materials for semi-dry Processes consist of a backing paper or a backing film, which / with a primer and a sensitizing solution. After Exposure is on both sides of the developer part of the blueprint machine Wet the recording material with the developer liquid. At a Further development of the process, the so-called thin-film process, will only be done wetted the image side with a very small amount of developer fluid to directly to get almost dry breaks. Because in the case of paper as Backing material becomes damp only on one side of the photosensitive paper, it is necessary for papers a barrier layer between the paper and apply light-sensitive coating to the flatness during development guarantee. The thin-film diazo blueprint process is described in detail in DE-A- 23 25 529. The appropriate light-sensitive materials are known from DE-A-25 22 173 and DE-A-25 40 393.

In the known processes, diazo compounds are used, which are very are reactive. This already leads to the production of the products in the Be Layering solution to thermal and photochemical problems Decomposition of these compounds with negative effects on the coated Blueprint material. Furthermore, the durability of the photosensitive materials relatively short because of the high reactivity.  

Conventional stabilizers, such as ZnCl₂, acids, such as. B. citric acid, tartaric acid or 1,3,6- and 1,3,7-naphthalene trisulfonic acid trisodium salt, only limited use and limited effectiveness in the Improve the shelf life of these diazo solutions and those made from them photosensitive diazo materials.

The use of cyclodextrins in thermally developing diazo Typical materials are described in JP-A 58124692. Then the cyclodextrin act in that the coupler, for. B. phloroglucin is complexed and thus the Reactivity of the coupler is reduced, so that the material has good durability having.

JP-A-49120629 and JP-A-51003220 disclose the use of cyclodextrin for Hot water developing or thermal developing diazonium layers for Stability improvement known.

CA-87104244 describes the use of cyclodextrin in two-component light paus materials for stabilization against pre-coupling reactions during the Storage described. The effect is based on reducing the reactivity of the Coupling component resorcinol by complexing the same.

The object of the present invention is to overcome the disadvantages of semi-dry diazo Blueprint materials, especially those due to the highly reactive diazo low stability of both the coating solution during manufacture and also the coated photosensitive material for their use clearly to improve without negatively affecting other properties of the semi-dry materials influence.  

This problem is solved by a 1-component diazo blueprint material for the semi-dry process or the thin-film process with on one flat carrier material arranged on one or both surfaces photosensitive recording layer (s) containing a semi-dry Ver driving / thin film process coupling water soluble diazonium salt and Contains conventional binders, pigments and auxiliaries, characterized in that the recording layer (s) cyclodextrin or a cyclodextrin derivative as Stabilizer included.

Α-Cyclodextrin, β-cyclodextrin, γ-cyclodextrin have been found to be particularly suitable or their derivatives resulting from substitution on the OH groups or Mixtures of the same proved.

Cyclodextrin or its derivatives is preferably in an amount of 1 mg / m 2 to 500 mg / m² present in the recording layer.

Surprisingly, it was found that cyclodextrins in semi-dry light material or in the thin-film process to an essential Improve stability when combined with the usual ones Diazonium compounds are used.

It was found that the addition of cyclodextrin or mixed various cyclodextrins or their derivatives to stabilize the photosensitive diazonium coating solution and improve the Durability of the unexposed blueprint material leads. Furthermore, a Reduction of yellowing of exposed areas of the finished breaks and one Reduction in fading of the image lines was observed under the influence of light.  

The development speed (coupling speed) with the im Liquid developers usual couplers, such as resorcinol and phloroglucin, changes at Presence of cyclodextrin not. This is surprising because of this Coupler such an effect has been described in 2-component materials.

According to the invention, β-cyclodextrin is very particularly preferred as a stabilizer used. The solubility of β-cyclodextrin in the diazonium compounds containing coating compositions is significantly above the solubility in pure water (approx. 1.8% at 23 ° C). This allows the use of β-cyclodextrins e.g. B. in equimolar amount to the diazonium compound.

Suitable carrier materials for the blueprint materials according to the invention are conventional opaque coating base papers, transparent papers, waterproof Papers and foils, e.g. B. from PETP and OPP. These backing materials will be by means of known coating methods, generally initially with a Provide pre-coating that the inclusion of the photosensitive substances in a second coating is used.

The precoat exists on conventional semi-dry materials Paper base from an aqueous dispersion of silica pigments, Binders such as As polyvinyl alcohol, casein, plastic dispersions, for. B. Polyvinyl acetate or styrene-acrylate dispersions, and auxiliaries, such as. B. Wetting agents, defoamers, thickeners, dyes, lubricants, stabilizers.

According to the invention, cyclodextrin can be used as an auxiliary in these coating solutions be incorporated. However, it is beneficial because of the improvement in Stability (service life), the inventive cyclodextrin in  to incorporate the solution of the photosensitive diazo compounds, which are based on the Pre-coating is applied. The effect achieved by the cyclodextrin is in Finished product the same.

Suitable cyclodextrins are α-, β-, γ-cyclodextrins and their derivatives, which are characterized by Etherification, esterification or other reaction on the free OH groups be preserved. These include e.g. B. hydroxypropyl-β-cyclodextrins or methylated β-cyclodextrins or β-cyclodextrin polymers. It is particularly suitable β-cyclodextrin for the claimed application.

In addition to the cyclodextrin, the light-sensitive coating contains diazonium compounds and other auxiliaries suitable for the semi-dry process. Suitable diazonium compounds include e.g. B. 1-diazo-2,5-diethoxy-4-para-tolylmercaptobenzol-1/2-ZnCl₄ salt, 1-diazo-2,5-dimethoxy-4-para-tolylmercapto-benzene-1/2-ZnCl₄ salt , 1-Diazo-2-chloro-4-diethylamino-5-para-chloro phenoxybenzene-1/2-ZnCl₄ salt, 1-diazo-2-chloro-4-dimethylamino-5-para-chloro-phenoxybenzene-1/2 -ZnCl₄ salt, 1-diazo-3-chloro-4-pyrrolidinobenzene-1/2-ZnCl₄ salt, 1-diazo-3-chloro-4-N, N-dibutylamino-benzene-1/2-ZnCl₄ salt , 1-diazo-3-chloro-4-N, N-diethylaminobenzene-1/2-ZnCl₄ salt, 1-diazo-3-chloro-4-N-methyl-N-cyclohexylamino benzene-1/2-ZnCl₄- Salt. Furthermore, the corresponding diazo compounds as counterions other groups than ZnCl₃⁻ or ZnCl₄ ^2- contain z. B. PF₆⁻, BF₄⁻, sulfosuccinate.

The aqueous photosensitive coating solution can also be used as auxiliary substances usual stabilizers, such as. B. Acids (tartaric acid, citric acid, 5- Sulfosalicylic acid, P-toluenesulfonic acid), and thiourea, urea or the like  Derviate, sugar, such as B. milk sugar, glucose, sorbitol, sodium salt of 1,3,6- or 1,2,7-naphthalene trisulfonic acid, dyes, wetting agents, such as. B. Isopropanol, saponin, humectants, such as. B. contain glycol and glycerin.

As a rule, both coatings are made in two in one machine run Commissioned works with subsequent dry sections, the Final moisture for paper coating between 2.0% and 4.5% residual moisture is provided.

In the copying process, the blueprint material is first of all using UV lamps in the Imagesetter part of commercially available blueprint devices or in the frame by means of pictures exposed to a transparent original and then through the wetting on both sides developed with 5-10 ml / m² developer liquid each. After drying the The copy is ready on the surface, possibly through a heatable drying section. The Developer liquid consists essentially of the coupler or couplers, e.g. B. Resorcinol and phloroglucin and buffer substances, e.g. B. sodium or potassium salt Succinic acid, tartaric acid malonic acid, benzoic acid, acetic acid. Furthermore are Auxiliaries for wetting and stabilization are common.

In the thin-film process, the developer is one-sided to the photosensitive Layer applied. In order to dry the concentrated developer liquid in Preventing the break machine are usually humectants such as Glycol and glycerin added to the developer. When using paper as Base material, it is advantageous to place a barrier layer under the photosensitive layer to install against water or developer, which prevents during development that the paper bends towards the back due to moisture absorption on one side.  

This is achieved by pre-coating the paper with plastic dispersions, which result in a water-repellent, non-swellable film, e.g. B. by styrene Butadiene latices or ethylene acrylic acid latices or vinyl acetate homo or Copolymers. This pre-coating also contains z. B. pigments, dyes and other excipients.

This barrier coating is then either described above Layers applied in two further coating steps or coated with a layer that contains all components, i.e. the pigments, binders, Contains diazonium salt and auxiliary substances. In both cases, the addition of Cyclodextrin positive on the parameters described above.

The positive effect of cyclodextrin on a solution of a light sensitive Diazonium compound can be seen in the following experiment: 2.5 g of 1-diazo 2,5-diethoxy-4-para-tolylmercaptobenzol-1/2-ZnCl₄⁻ salt together with 0.8 g tartaric acid and 10 ml isopropanol dissolved in 90 ml distilled water. In 50 ml 3.0 g of β-cyclodextrin are added to the resulting solution quickly resolves. When the two solutions obtained are left to stand under the influence of light you can see that the solution that does not contain cyclodextrin quickly becomes cloudy, while the solution with cyclodextrin clears over a long period (hours) remains. The separation of oily substances at the Liquid surface is suppressed by cyclodextrin.  

The advantages of cyclodextrin for the blueprint semi-dry process are apparent the following examples:

Test methods Stability of the photosensitive coating solution

The finished coating solution is placed in a beaker with low lighting touched. After 3 h no oily components appear on the surface and Laboratory strokes after exposure and development do not give a clear result Change in background color, line art and sensitivity to light the stability was assessed as good.

Shelf life of the unexposed material

The unexposed material is in the dark at 30 ° C / 83% r. F. 3 days or 40 ° C / 25% r. F./14 days stored in a climatic cabinet. After that, the material exposed until the diazonium compounds are completely destroyed and with commercial liquid developer developed. The color difference Δ E according to DIN 6174 to the same material that was directly exposed and developed is done with a Colorimeter determined. The higher the measured Δ E value, the poorer durability the material has.

Yellowing due to light / fading of the image lines

The blueprint material is exposed and developed (yellowing of the Background) or developed to full tone (bleaching of the azo dye). The so prepared samples are compared with the respective comparative sample 2 weeks in one  Interior exposed to diffuse daylight. Using a colorimeter the color difference Δ E between freshly developed material and the light exposed material determined. The higher the Δ E value, the stronger it became the full tone or the exposed background is changed by the light.

Development speed

The sample and the comparative sample are placed side by side at the same time without prior Exposure in a standard blueprint machine with semi-dry development or thin-film development.

The development of the black solid tone is after leaving the developer part observed. If the black solid is formed within one minute, the Development speed described as good.

Example 1 (comparison)

A suitable 74 g / m² base paper is first washed with an aqueous one Pre-coating of 2.5 g / m² fixed application coated with an air brush. The For 1 l of solution, the coating solution contains:

50 g of commercially available precipitated silica
30 g casein
35 g polyvinyl acetate plastic dispersion (commercially available)
0.2 g defoamer
3.0 ml ammonia 25%

After application to the base paper, the coating is hot air dried.

Then this paper is coated with a solution on the pre-coated side sensitized the following components:

900 ml of water
35 g of 1-diazo-2,5-diethoxy-4-para-tolyl mercaptobenzene 1/2-ZnCl₄ salt
15 g of 1-diazo-2-chloro-4-diethylamino-5-para-chlorophenoxy-benzene-1/2-ZnCl₄ salt
30 g tartaric acid
40 g ZnCl₂
0.1 g saponin
50 ml isopropanol

20 ml / m² of this solution are applied with an air brush and the paper then dried with hot air to a final moisture content of 3.5%.

The test results with the standard semi-dry blueprint paper obtained are shown in Table 1.

Example 2

The coatings are carried out as in Example 1, except that the Diazo solution as stabilizer a mixture of 20 g α-cyclodextrin and 20 g β- Cyclodextrin is added. The paper is made by adding cyclodextrin significantly improved (see Table 1).  

Example 3 (comparison)

A suitable 65 g / m² is used to produce a thin-layer blueprint paper Paper first using a doctor blade with a barrier layer with a dry application of 6.5 g / m² Mistake. 1 l of barrier layer dispersion contains:

420 ml styrene-butadiene plastic dispersion 50%
60 g commercially available silica (precipitated)
0.1 g blue dye
0.5 g defoamer
20 ml isopropanol

After this coating has dried, the photosensitive layer is applied Apply a layer of 18 ml / m² to the coated side using airbrush dosing. 1 l of Sensitization solution contains:

45 g commercially available silica (precipitated)
5 g commercially available silica (precipitated)
0.1 g blue dye
80 ml isopropanol
15 m ethylene glycol
3.0 g ZnCl₂
20 g polyvinyl alcohol (commercially available)
80 g polyvinyl acetate plastic dispersion 50%
16 g of 1-diazo-2,5-diethoxy-4-para-tolyl mercaptobenzene 1/2-ZnCl₄ salt
16 g of 1-diazo-2-chloro-4-diethylamino-5-para-chlorophenoxy-benzene-1/2-ZnCl₄ salt
1.2 g wetting agent / defoamer

The coating is dried with hot air so that the paper has a final moisture reached by 3%. The test result is shown in Table 1.

Example 4

The coatings are carried out as in Example 3, except that the Diazo solution as a stabilizer 30 g of β-cyclodextrin is added. The paper will significantly improved by the addition of β-cyclodextrin (see Table 1).  

Table 1

Claims (6)

1. 1-component diazo blueprint material for the semi-dry process or the thin-film process with a light-sensitive recording layer arranged on a planar support material on one or both surfaces, which contains a water-soluble diazonium salt coupling in the semi-dry process / thin-film process and conventional binders, pigments and auxiliaries, characterized in that that the recording layer contains cyclodextrin or a cyclodextrin derivative as a stabilizer. 2. 1-component diazo blueprint material according to claim 1, characterized records that the cyclodextrin (derivative) from α-, β-, γ-cyclodextrin, whose by Substitution on the OH groups resulting derivatives, or mixtures the same is selected. 3. 1-component diazo blueprint material according to one of claims 1 or 2, characterized characterized in that cyclodextrin or its derivatives in an amount of 1 mg / m² to 500 mg / m² is present in the recording layer. 4. 1-component diazo blueprint material according to one of claims 1-3, characterized in that the diazonium salt from 1-diazo-2,5-diethoxy-4- paratolyl mercaptobenzene-1/2-ZnCl₄ salt, 1-diazo-2,5-dimethoxy-4-paratolylmer captobenzol-1/2-ZnCl₄ salt, 1-diazo-2-chloro-4-diethylamino-5-para-chlorine phenoxy-benzene-1/2-ZnCl₄ salt, 1-diazo-2-chloro-4-dimethylamino-5-para-chlorine phenoxybezol-1/2-ZnCl₄ salt or mixtures thereof is selected. 5. Process for developing a 1-component diazo blueprint material according to one of claims 1-4 after its imagewise exposure by means of a Liquid developer in the semi-dry process with developer application on both sides of 5-10 ml / m² each on the surface (s) of the material. 6. Process for developing a 1-component diazo blueprint material according to one of claims 1-4 after its imagewise exposure by means of a Liquid developer in the thin film process with one - sided developer application from 2-5 ml / m² on the recording layer.