DE1217784B - Process for the production of planographic printing forms with an aluminum base - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. α .:

G03f

German KL: 57 d-2/01

Number: 1 217 784

File number: A 32938IX a / 57 d

Filing date: September 26, 1959

Opening day: May 26, 1966

It is already known that silver images produced by photographic means by oxidation in heavy metal and / or transferring silver salt images and converting them with organic compounds, which contain SH, SeH or NH groups, resulting in 5 sparingly soluble salt-like compounds, that accept bold inks.

From the processing of commercially available photographic materials for the production of planographic printing plates there is also known a method of converting silver photographic images by the silver salt diffusion method on unprepared aluminum plates with a rough surface suitable for planographic printing and deposited by subsequent Treatment with organic compounds that are adsorbed on metallic silver, these Silver images are made hydrophobic in such a way that they accept fat printing inks. One gets in this way Planographic printing forms.

Suitable organic compounds that adsorb onto metallic silver are from the German patents 1,058,844 and 1,064,343 known, e.g. B. 2,5-dimercapto-l, 3,4-thiodiazole, 5-mercapto-3-phenyl-l, 3,4-thiodiazolthione-2, 5-mercaptotetrazole, 1-phenyl-5-mercaptotetrazole, 3-mercapto-1,2,4 - triazole, 1 - phenyl - 3 - mercapto -1,2,4 - triazole, 2,4,6-trimercapto -1,3,5 - triazine, 2 - mercapto - 4,5 - dimethyl-6-oxypyrimidine, 6-mercaptopurine, tetraethylthiuram disulfide, thiourea, phenylthiourea, Phenylthiosemicarbazide, diphenylthiosemicarbazide, diphenylthiocarbazone, diphenylcarbazide and compounds the general formula

Process for the production of
Planographic printing forms with a
Aluminum base

R - X - C - NH - NH ₂
Y

where R = alkyl, X = O, S, NH and Y = O or S means.

The quality of the hydrophobization of the silver images achieved with these compounds is, however, in many ways Cases not satisfactory, as either the color acceptance increases due to insufficient water repellency is low or with good ink acceptance, the resistance of the hydrophobized silver images to the influence of the atmosphere and compared to dilute phosphoric acid is low. A consistency

N-

Applicant:

Agfa Aktiengesellschaft,

Leverkusen, Kaiser-Wilhelm-Allee 24

Named as inventor:

Dr. Anita von König, Leverkusen

the hydrophobized silver images against atmospheric influences is therefore necessary because the finished planographic printing forms are stored in the printing works for a few hours or days. The finished planographic printing forms must be resistant to dilute phosphoric acid because as Fountain solutions phosphoric acid solutions are used and therefore the printing inks and dampening systems the printing machines as well as the sponges used to rub off the excess fixative may contain phosphoric acid in the course of use.

For practical use it is advantageous if the used to make the silver images water-repellent organic compounds in the fixing solutions customary in planographic printing, e.g. B. aqueous Solutions of gum arabic, polyvinyl alcohol, carboxymethyl cellulose and others, which are made using phosphoric acid or phosphates are adjusted to a pH value between 4 and 6, soluble or suspendable without the use of organic solvents, as these interfere with printing by removing the Dissolve printing inks.

It has now been found that obtained by the silver salt diffusion process on aluminum plates Silver images can be brought to good color acceptance if one is used for the water repellency Solution or suspension used, the derivatives of 2,5-Dimercapto-l, 3,4-thiodiazole with at least two Mercapto groups, two 1,3,4-thiodiazole radicals being bonded via an organic radical, according to of the following general formula:

N-

HS '

! - (CH ₂ ) «- SS

609 570/319

where η is an integer, preferably 1 to 10.

The silver images rendered hydrophobic with such a solution or suspension are resistant to atmospheric influences and extremely resistant to dilute phosphoric acid.

The compounds of the formula can be prepared as follows: 2 moles of 2,5-dimercapto-1,3,4-thiodiazole are dissolved in a solution of 2 moles of sodium or potassium hydroxide in 1200 cm ^{3 of aqueous alcohol (85 percent by volume).} 1 mol of an ω-dihaloalkane is added to this solution. The solution is refluxed for 2 to 6 hours and, after cooling, the precipitated product is suction filtered and washed free of halogen. The yield is 85 to 95%. The products are cleaned by recrystallizing from alcohol or by repeating them. The following table shows the melting points of some of the compounds so prepared:

Table 1 Table 2

Emulsifier

number of Melting point link CH ₂ groups
in formula I. 174 to 176 ° C A. «= 1 214 to 216 ° C B. k = 2 162 to 163 ⁰ C C. n = 3 191 to 193 ° C D. «= 4 162 to 163 ⁰ C E. n = 6 131 to 132 ° C F. η = 10

35

The compounds are used in amounts of about 5 to 20 g / l in an aqueous alkaline solution or suspended in the fixing solutions customary in planographic printing with the aid of emulsifiers. The well-known Way produced by the silver salt diffusion process on an aluminum foil with a rough surface Silver images are rendered hydrophobic by being coated with these solutions or suspensions.

It is also possible to separate a solution of the compounds and the acidic fixing solution one after the other To use operations.

However, it is more convenient to make the connections with a planographic printing with aluminum plates per se known fixing solution, e.g. B. aqueous solutions of gum arabic, polyvinyl alcohol, carboxymethyl cellulose inter alia, which can be adjusted to a pH value between 4 and 6 with the help of phosphoric acid or phosphates are set to combine. The film can then after the simultaneous hydrophobization of the Silver image and the fixation of the plate in the usual way with printing ink by hand or on the Printing machine rubbed or rolled. The printing parts are characterized by a large Adhesive strength for bold printing ink. Flawless prints up to a run length of about 5000 pieces are produced.

In order to produce stable suspensions in the acidic fixing solutions, the compounds must be emulsified by means of preferably anionic emulsifiers. Suitable emulsifiers and emulsifying aids Medium are given in Table 2.

constitution

1 sulfated castor oil

2 secondary alkyl sulfate

3 Na oleoyl isethionate

4 acid diethylamine oleate

5 di-naphthyl methanesulfonate

6 sulfonated ricinoleic acid dibutylamide

7 polyglycol
Coconut fatty alcohol sylate

example 1

50 g of compound B (Table 1) are ^{mixed with 100 cm 3 of} emulsifier 4 (Table 2), preferably in a mixer, e.g. B. Cutting mill, rocker mill, high-pressure homogenizer, swirl chamber high-speed stirrer or three-roller steel, etc., suspended. The homogeneous suspension is ^{dispersed in 4900 cm 3 of} a 10% strength aqueous polyvinyl alcohol solution and the dispersion is adjusted to pH 4.4 with 10% strength phosphoric acid. A silver image produced on an aluminum offset plate by the silver salt diffusion process is rubbed with the above dispersion. The excess is wiped off with a damp sponge, which is followed by printing. _;

Example 2

75 g of compound A (Table 1) are suspended in a mixing apparatus in 150 cm ³ of a 50 ° / ₀ aqueous solution of emulsifier 1 (Table 2). The homogeneous mixture is ^{dispersed in 4850 cm 3 of} a 7% strength aqueous carboxymethyl cellulose. The dispersion is adjusted to pH 5.2 with 10% phosphoric acid. Use as in example 1.

Example 3

100 g of compound F (Table 1) are ^{mixed with 20 cm 3 of} a 20% commercial solution of emulsifier 2 (Table 2) and 200 cm ^{3 of} polyglycol and 100 g of aqueous gum arabic solution 1: 1 in a ball mill for 3 hours. The homogeneous mixture is ^{dispersed in 4800 cm 3 of} a 2.0% strength aqueous carboxymethyl cellulose solution and the dispersion is adjusted to pH 4.6 with 10% strength phosphoric acid. Use as in example 1.

Example 4

50 g of Compound D (Table 1) with 7.5 cm ³ of a 20 ° / ₀ strength commercial solution of the emulsifier 2 (Table 2), 50 cm ³ polyglycol and 50 cm ³ of a 10% aqueous solution of polyvinylpyrrolidone (molecular weight mixed for about 700,000) in a mixing apparatus, and dispersed for ³ a 2.5 ° / _o aqueous solution of carboxymethyl cellulose in 4900 cm. The dispersion is adjusted to a pH of 4.1 with 10% phosphoric acid. Use as in example 1.

Example 5

A silver image produced on an aluminum offset plate using the silver salt diffusion process is with a solution of 5 g of compound C (Table 1)

Treated in 100 cm ³ l, 8% potassium hydroxide solution. According to this hydrophobization the disk at a 25 ° / _o aqueous solution of gum arabic which is adjusted with phosphoric acid to pH 4.0, is rubbed and printed.

Example 6

40 of Compound B g (Table 1) ³ 2 ° / _o aqueous solution of the emulsifier suspended in 100 cm 5 (Table 2) and then in 4900 cm ³ of a 10 ⁰ / o aqueous solution of polyvinylpyrrolidone (molecular weight about 700,000), which is set at 10 ° / ₀ phosphoric acid to a pH value of 4.3, are dispersed. Use as in example 1.

Example 7

50 g of compound E (Table 1) are dissolved in 2.5 cm ³ of a 20 ° / ₀ strength commercial solution of the emulsifier 2 (Table 2), 2.5 cm ^{3 of} 20% emulsifier 3 (Table 2) and 100 cm ³ Polyglycol suspended and ao then ^{dispersed in 4900 cm 3 of} 2.5% strength aqueous carboxymethyl cellulose solution and the dispersion is adjusted to pH 4.1 with phosphoric acid. Use as in example 1.

25th

Example 8

60 g of compound C (Table 1) are dissolved in 6.0 cm ³ emulsifier 8 (20% ^he aqueous solution) and suspended 150 cm ³ polyglycol and then in 4850 cm ³ of 2 ° / _o aqueous sodium alginate solution, 436 g of the primary Contains potassium phosphate and 48.5 g of secondary sodium phosphate and has a pH of 5.7, dispersed. Use as in example 1.

Example 9

50 of compound D g (Table 1) cm mixed with cm ³ of 20 ° / _o strength commercial solution of the emulsifier 2 (Table 2), and 100 ³ of a 1.5 ° / _o aqueous solution of a Alginsäurepropylenglykolesters in a mixing apparatus and in 4890 cm ^{3 of} a% strength aqueous alginic acid propylene glycol ester solution dispersed.

Example 10

60 g of compound E (Table 1) are ^{mixed with 12 cm 3 of} a 20% strength aqueous solution of the emulsifier 8 (Table 2) and 150 cm ^{3 of} a 1.5% strength aqueous solution of an alginic acid amide in a mixer and in a mixture from 1850 cm ^{3 of} a% strength aqueous alginic acid propylene glycol ester solution and 3000 cm ^{3 of} a 2% strength aqueous carboxymethyl cellulose solution. The dispersion is adjusted with a 10 ° / ₀ phosphoric acid to pH 4.3.

Claims (3)

Patent claims: 1. Process for the production of planographic printing forms using according to the silver salt diffusion process silver images produced on an aluminum plate, characterized in that that these silver images are treated with an aqueous solution or dispersion, the derivatives of 2,5-Dimercapto-1,3, 4-thiodiazoles with at least two mercapto groups, with two 1,3,4-thiodiazole residues above an organic bridge member are bound, according to the following general formula: N-, C, HS -N Il - (CH ₂ ) ,, N- Il , C, -N Il
, c, where η is an integer. 2. The method according to claim 1, characterized in that the silver images are treated with a dispersion which, in addition to the said thiodiazole derivatives, a known preservative such as carboxymethyl cellulose, polyvinyl alcohol, gum arabic, sodium alginate, alginic acid ester and alginic acid amide, among others, and phosphoric acid and / or acid Contains water-soluble phosphates.
3. The method according to claim 1 and 2, characterized in that the silver images with a Dispersion treated using emulsifiers and emulsifying aids known per se was produced.