EP0273263B1 - Light-sensitive mixture with diazonium salt polycondensation products, and light-sensitive registration material prepared therewith - Google Patents

Description

The invention relates to a light-sensitive mixture which contains a diazonium salt polycondensation product and a polymeric binder and which is particularly suitable for the production of printing plates.

From DE-A 30 36 077 (= US-A 4 387 151) it is known to produce photosensitive mixtures of mixed condensation products of condensable diazonium salts and other non-photosensitive condensable compounds, in combination with polymeric binders which contain pendant alkenylsulfonylurethane groups, for the production of printing plates to use. These mixtures can be developed with purely aqueous, alkaline solutions. When processed into planographic printing plates, however, they result in light-hardened layers whose color acceptance is unsatisfactory.

DE-A 24 29 251 describes similar light-sensitive mixtures which contain, as binders, organic synthetic resins with free hydroxyl or carboxyl groups which have been reacted with polyvalent isocyanates, epoxides or acid anhydrides as crosslinking agents. The mixtures contain partly unreacted crosslinking groups and partly insoluble components, so that their storability and developability is limited.

EP-A 152 819 discloses light-sensitive mixtures of diazonium salt polycondensation products and binders containing carboxyl groups, which have been obtained by reacting polymers containing hydroxyl groups with acid anhydrides. These mixtures can be developed with aqueous-alkaline solutions and are suitable for the production of planographic printing plates with high circulation rates. However, a further increase in the circulation of these mixtures is desirable. It is therefore recommended in this publication to use other polymers, e.g. As polyurethanes, to increase the abrasion resistance in a smaller amount. However, this combination leads to copying disadvantages, e.g. B. to an undesirable dot gain. This also affects the developability and storage stability.

Finally, US Pat. No. 3,660,097 and DE-A 27 39 774 disclose mixtures of the type specified, in which polyurethane resins are used as polymeric binders. The disadvantage of these mixtures is that the binders are poorly soluble in the usual coating solvents and the solutions have to be filtered several times to remove insoluble residues. The aqueous-alkaline developability of these mixtures is very limited and the print run that can be achieved is insufficient for a high-performance range.

A similar mixture is known from EP-A 0 030 001, which contains a branched polyurethane as a binder. Although relatively large print runs can be achieved with the aid of this mixture, it also has some disadvantages. For example, for a fog-free, rapid development of the light-cured layer, use should preferably be made of acidic aqueous developer solutions, which can lead to corrosion problems in the light metal parts of the developer machines during machine processing.

The object of the invention was to propose a negative-working light-sensitive mixture which is suitable for the production of printing plates, in particular planographic printing plates, and which has all the advantages of the best known mixtures based on diazonium salt polycondensation products and which can be used with practically solvent-free neutral or alkaline aqueous solutions Allows solutions to be developed and the printing plates to be produced with a higher number of copies without impairing developability and storage stability.

According to the invention, a light-sensitive mixture is proposed which contains a diazonium salt polycondensation product and a non-light-sensitive polymeric binder with pendant carboxyl groups, which is soluble or at least swellable in aqueous alkaline solutions and a reaction product of an intramolecular anhydride of an organic polycarboxylic acid with a hydroxyl-containing polymer which contains no other functional groups capable of reacting with acid anhydrides,

The mixture according to the invention is characterized in that the binder also carries pendant urethane-containing substituents which are formed by reacting organic monoisocyanates with hydroxyl groups of the polymer.

R^a und R^c

ggf. substituierte Alkyl-, Alkenyl- oder Arylreste sind und

R^b

ein ggf. substituierter Alkylen-, Cycloalkylen-, Arylen- oder Arylenalkylenrest ist.

The organic monoisocyanates used to produce the new binders can also contain minor amounts of polyvalent isocyanates. If diisocyanates are used, care must be taken to ensure that their proportion is not too high, since otherwise crosslinked, insoluble reaction products can arise. The isocyanates can be aliphatic or aromatic compounds. Compounds according to one of the formulas IV and V are preferred:



R ^a -NCO (IV) R ^c -O-CONH-R ^b -NCO (V)



wherein

R ^a and R ^c

are optionally substituted alkyl, alkenyl or aryl radicals and

R ^b

is an optionally substituted alkylene, cycloalkylene, arylene or arylenealkylene radical.

The radical R ^a is preferably an alkyl radical with 1 to 18, in particular 1 to 7, carbon atoms, a cyclohexyl radical, an alkenyl radical with 2 to 6 carbon atoms or an aryl radical with 6 to 12 carbon atoms, in particular a phenyl radical. If R ^{b is} an aliphatic radical, it preferably has 4 to 10 carbon atoms, and as an aromatic radical it preferably has 6 to 12 carbon atoms. R ^c is preferably an aliphatic radical and has 1 to 12 carbon atoms.

Suitable substituents for the radicals R ^a , R ^b and R ^c are in particular alkyl, alkoxy, alkoxyalkyl, cycloalkyl, aryl, aryloxy, aralkyl, acyl, acyloxy, alkoxycarbonyl radicals and halogen atoms.

Examples of isocyanates of the general formula IV are methyl, ethyl, propyl, isopropyl, butyl, hexyl, cyclohexyl or octadecyl isocyanate and phenyl, tolyl, chlorophenyl, fluorophenyl or naphthyl isocyanate. Unsaturated isocyanates such as allyl isocyanate or substituted isocyanates such as alkyl isocyanatoalkanoic acid are also suitable. Most of the isocyanates listed are commercially available or can be prepared according to known working procedures.

The isocyanates of the general formula V can be prepared in a known manner by reacting a diisocyanate with an alcohol in such a way that only one of the two isocyanate functions is reacted. In question come as isocyanates z. B. aliphatic diisocyanates such as 1,6-diisocyanatohexane or 1,4-diisocyanatocyclohexane, aromatic diisocyanates such as 1,4-diisocyanatobenzene or 2,4-diisocyanatotoluene, or mixed aromatic-aliphatic diisocyanates such as 1-isocyanato-3-isocyanatomethyl benzene or 1,3-bis-isocyanatomethyl-benzene. Alcohols which can be used are simple aliphatic alcohols, such as methanol, ethanol, propanol, butanol or the like, aliphatic ether alcohols, such as ethylene glycol monoalkyl ether or propylene glycol monoalkyl ether, and monoethers of di- or triethylene glycol, monoesters of aliphatic diols, such as ethylene glycol monoacetate, or araliphatic alcohols, or alcoholic alcoholic benzyl alcohols, Find use.

The acid anhydride is preferably derived from a di- or tricarboxylic acid, in particular a dicarboxylic acid, and can contain one, two or more rings.

erhalten, worin

R¹ und R²

einzeln Wasserstoff-, Halogenatome oder Alkylgruppen bedeuten oder miteinander zu einem aromatischen oder heteroaromatischen, gegebenenfalls substituierten und ggf. teilweise hydrierten 5- oder 6-gliedrigen Ring verbunden sind, an den bis zu zwei aromatische oder cycloaliphatische Ringe ankondensiert sein können,

R³, R⁴ und R⁵

einzeln Wasserstoffatome oder Alkylgruppen bedeuten oder

R³ und R⁵

miteinander zu einem ggf. substituierten gesättigten oder ungesättigten aliphatischen Ring verbunden sind, der einschließlich X fünf oder sechs Ringglieder haben kann,

R⁶ und R⁷

Wasserstoffatome oder Alkylgruppen,

X

eine Einfachbindung, eine 1,1-Alkylengruppe, eine 1,1-Cycloalkylengruppe, die ggf. substituiert sind, ein Sauerstoff- oder Schwefelatom,

Y

ein Sauerstoff- oder Schwefelatom, eine 1,1- oder 1,2-Alkylengruppe oder eine 1,2-Alkenylengruppe, an die ggf. ein aromatischer oder cycloaliphatischer Ring ankondensiert ist, und

Z

die zur Vervollständigung eines gesättigten oder ungesättigten ggf. substituierten Rings erforderlichen Ringglieder bedeuten, wobei an diesen Ring bis zu zwei aromatische oder cycloaliphatische Ringe ankondensiert sein können.

Particularly preferred binders are reacted with acid anhydrides of one of the formulas I, II or III

get what

R1 and R2

individually denote hydrogen, halogen atoms or alkyl groups or are linked to one another to form an aromatic or heteroaromatic, optionally substituted and optionally partially hydrogenated 5- or 6-membered ring to which up to two aromatic or cycloaliphatic rings can be fused,

R³, R⁴ and R⁵

individually represent hydrogen atoms or alkyl groups or

R³ and R⁵

are linked together to form an optionally substituted saturated or unsaturated aliphatic ring which, including X, can have five or six ring members,

R⁶ and R⁷

Hydrogen atoms or alkyl groups,

X

a single bond, a 1,1-alkylene group, a 1,1-cycloalkylene group which are optionally substituted, an oxygen or sulfur atom,

Y

an oxygen or sulfur atom, a 1,1- or 1,2-alkylene group or a 1,2-alkenylene group, to which an aromatic or cycloaliphatic ring is optionally fused, and

Z

mean the ring members required to complete a saturated or unsaturated optionally substituted ring, it being possible for up to two aromatic or cycloaliphatic rings to be fused onto this ring.

If R¹, R², R³, R⁴, R⁵, R⁶ or R⁷ are alkyl groups, these generally have 1 to 4, preferably 1 to 2, carbon atoms. Substituents that can be attached to the aromatic or cycloaliphatic rings are e.g. B. alkyl groups, alkoxy groups, halogen atoms, nitro groups or carboxyl groups.

Examples of suitable acid anhydrides are given in EP-A 152 819. The reaction products with maleic, chloromaleine, hexahydrophthalic, phthalic, succinic, trimellitic and 3-oxa-glutaric anhydride are preferred.

Polymers containing hydroxyl groups include, in particular, polymers with vinyl alcohol units, but also epoxy resins and saponified epoxy resins, polyamides, polyurethanes or polyesters with free OH groups, copolymers of allyl alcohol or higher unsaturated ones Alcohols, polyhydroxyalkyl acrylates and methacrylates or their copolymers, natural hydroxyl-bearing polymers, such as cellulose esters and ethers and similar polymers containing free OH groups, are considered.

Partially saponified polyvinyl esters, polyvinyl acetals with free hydroxyl groups, in particular polyvinyl formals and butyrals, and corresponding reaction products of copolymers or copolymers with vinyl ester or vinyl acetal or vinyl alcohol units are suitable as polymers with vinyl alcohol units. The OH number of these starting polymers should be in the range between 30 and 700, preferably from 100 to 500. The molecular weight distribution, i.e. H. the dispersity of these polymers should be as small as possible.

The molecular weight of the carboxyl group-containing binders is generally between 5,000 and about 200,000 and above, preferably between 10,000 and 100,000. The acid number of the binders can generally be between 10 and 120, preferably between 15 and 100.

The binders contained in the mixture according to the invention have lateral urethane and carboxyl groups. The binders should advantageously contain at least 1% by weight of urethane groups (-OCONH-) and at least 3% by weight of carboxyl groups. The upper limit for the content of urethane and carboxyl groups is not critical, but it has proven to be favorable for the abrasion resistance of the printing forms obtained with the recording material according to the invention if about 5 to 80% by weight of the OH groups of the starting polymer remain unreacted. The polymers should preferably contain about 1 to 15, in particular 1.5 to 10,% by weight of urethane groups.

The reaction between isocyanate, acid anhydride and polymers containing hydroxyl groups is very clear and in many cases quantitative; it can therefore be reproduced very well. It is therefore possible to very precisely and reproducibly the desired acid number of the binder and the desired amount of urethane groups, e.g. for using a particular developer.

The reaction can be carried out in ketones, e.g. Butanone, or tetrahydrofuran or dioxane can be carried out. Tertiary amines are expediently used as catalysts. In general, 0.5 to 80 parts by weight of anhydride, 1000 to 3000 parts by weight of solvent and 0.5 to 5 parts by weight of tertiary amine are used per 100 parts by weight of polymer containing hydroxyl groups.

To prepare the new binders, the hydroxyl-containing starting polymer is first dissolved in a suitable, anhydrous solvent, if appropriate in the heat. This solution becomes a basic one Catalyst, preferably diaza-bicyclo [2.2.2] octane, added and then the corresponding isocyanate, optionally in dissolved form, was added dropwise. The reaction mixture sometimes heats up; To complete the reaction, the mixture is kept at temperatures between 50 and 120 ° C. for about 4 to 24 hours. The completion of the desired reaction is determined by checking the free isocyanate content. After the completion of the reaction, the mixture is again mixed with a basic catalyst, preferably triethyl or tributylamine, and then with the required amount of the anhydride. The mixture is again brought to temperatures between 50 and 120 ° C and left for about 5 to 10 hours. The cooled solution of the binder is then ready for use and can be used in the specified coating solutions.

For some applications, the polymer may need to be isolated in solid form. For this purpose, the reaction solution is dropped into a large amount of a suitable non-solvent, especially in water. The precipitated polymer is filtered off and dried.

The polymers of the invention can also be prepared by first carrying out the reaction with the anhydride and then the reaction with the isocyanate. However, it has been shown that the polymers obtained are not always clearly reproducible can be obtained. In addition, it was found that more drastic reaction conditions often have to be used in this reaction procedure. Therefore, this order of implementation is not preferred.

As diazonium salt polycondensation products are condensation products of condensable aromatic diazonium salts, e.g. B. of diphenylamine-4-diazonium salts, with aldehydes, preferably formaldehyde, suitable. Mixed condensation products which contain, in addition to the diazonium salt units, other, non-photosensitive units derived from condensable compounds, in particular aromatic amines, phenols, phenol ethers, aromatic thioethers, aromatic hydrocarbons, aromatic heterocycles and organic acid amides, are used with particular advantage. These condensation products are described in DE-A 20 24 244. In general, all diazonium salt polycondensation products are suitable, which are described in DE-A 27 39 774.

Q

das Anion der Diazoniumverbindung,

p

eine ganze Zahl von 1 bis 3,

R⁸

einen aromatischen Rest mit mindestens einer zur Kondensation mit aktiver Carbonylverbindung befähigten Position,

R¹⁰

eine Phenylengruppe,

R⁹

eine Einfachbindung oder eine der Gruppen:

-(CH₂)_q-NR¹¹-,
-O-(CH₂)_r-NR¹¹-,
-S-(CH₂)_r-NR¹¹-,
-S-CH₂CO-NR¹¹-,
-O-R¹²-O-,
- O -
- S - oder
-CO-NR¹¹-
bedeuten, worin

q

eine Zahl von 0 bis 5,

r

eine Zahl von 2 bis 5,

R¹¹

Wasserstoff, eine Alkylgruppe mit 1 bis 5 C-Atomen, eine Aralkylgruppe mit 7 bis 12 C-Atomen oder eine Arylgruppe mit 6 bis 12 C-Atomen, und

R¹²

eine Arylengruppe mit 6 bis 12 C-Atomen ist.

The diazonium salt units A-N₂Q are preferably derived from compounds of the formula (R⁸-R⁹-) _p R¹⁰-N₂Q, wherein

Q

the anion of the diazonium compound,

p

an integer from 1 to 3,

R⁸

an aromatic radical with at least one position capable of condensation with an active carbonyl compound,

R¹⁰

a phenylene group,

R⁹

a single bond or one of the groups:

- (CH₂) _q -NR¹¹-,
-O- (CH₂) _r -NR¹¹-,
-S- (CH₂) _r -NR¹¹-,
-S-CH₂CO-NR¹¹-,
-O-R¹²-O-,
- O -
- S - or
-CO-NR¹¹-
mean what

q

a number from 0 to 5,

r

a number from 2 to 5,

R¹¹

Hydrogen, an alkyl group with 1 to 5 carbon atoms, an aralkyl group with 7 to 12 carbon atoms or an aryl group with 6 to 12 carbon atoms, and

R¹²

is an arylene group with 6 to 12 carbon atoms.

The mixtures according to the invention generally contain 5 to 90, preferably 10 to 70% by weight of diazonium compound and 95 to 10, preferably 90 to 30% by weight of polymeric binder.

To stabilize the light-sensitive mixture, it is advantageous to add a compound with an acid character to it. Mineral acids and strong organic acids are possible, of which phosphoric acid, sulfuric acid, perchloric acid, boric acid or p-toluenesulfonic acid are preferred. A particularly suitable acid is phosphoric acid. The mixtures Plasticizers, adhesion promoters, dyes, pigments and color formers can also be added.

The type and amount of these additives depend on the area of application intended for the light-sensitive mixture. It is important to note that the added substances do not absorb an excessive amount of the actinic light necessary for the crosslinking and thereby reduce the practical sensitivity to light.

The light-sensitive mixtures can also contain dyes and / or pigments, which can act both as a contrast agent and as a layer-strengthening agent. Suitable dyes are given, for example, in US Pat. Nos. 3,218,167 and 3,884,693. Z are particularly suitable. B. Victorian blue FGA (C.I. Basic Blue 81), Renol blue B2G-H (C.I. 74160), crystal violet or Rhodamine 6 GDN (C.I. 45160). Metanil yellow (C.I. 13065), methyl orange (C.I. 13025) or phenylazodiphenylamine can be used to increase the image contrast after exposure.

In the context of the invention, the following weight-based distribution of the most important additives in the light-sensitive mixture is preferred, based on the content of non-volatile constituents, ie the constituents of the solid light-sensitive layer obtained after evaporation of the solvent. binder 30 to 90% Diazonium salt polycondensation product 10 to 70% acid 0 to 10% Dye or pigment 0 to 12% Exposure Contrast Agent (Dye) 0 to 5%

The carrier material is coated from appropriate organic solvents or solvent mixtures, generally by pouring, spraying or dipping.

Alcohols, ketones, esters, ethers and the like are suitable as solvents. The partial ethers of the glycols or the keto alcohols have proven to be cheap solvents, e.g. B. ethylene glycol monomethyl ether or propylene glycol monomethyl ether.

As layer supports are, for. As magnesium, zinc, copper, mechanically, chemically and / or electrochemically roughened aluminum, anodized aluminum, steel, but also polyester or cellulose acetate film, perlong gauze, etc., the surface of which may be subjected to a pretreatment if necessary. The carrier material can act as the final layer carrier or as a temporary carrier material from which the light-sensitive layer is transferred to the workpiece to be processed by means of lamination.

The recording material produced with the light-sensitive mixtures is used on the one hand for production of images on suitable supports or receiving sheets, on the other hand for the production of reliefs, which are used as printing forms, screens, reserves and the like.

In addition, however, it is also possible to use the light-sensitive mixtures for the production of lacquers curable by UV radiation, which can be used as surface protection, or for the formulation of UV-curable printing inks.

The mixture is particularly preferably used for the production of planographic printing forms, aluminum being preferred as the carrier material.

Aluminum is particularly preferred, which is pretreated for this purpose in the usual way, e.g. B. by mechanical, chemical and / or electrochemical roughening and optionally subsequent anodic oxidation. Another treatment of this carrier material, e.g. B. with polyvinylphosphonic acid, alkali silicate, phosphate, hexafluorozirconate, chromate, borate, polyacrylamide and cellulose derivatives is advantageous.

The recording materials obtained from the mixtures are processed in a known manner by imagewise exposure and washing out of the unexposed areas of the layer with a suitable developer.

The exposure of the recording material takes place in a known manner under a template with copy light sources which emit the highest possible spectral component in the near ultraviolet range. It can also be done by laser radiation. Suitable for the irradiation are power-appropriate shorter-wave lasers, for example Ar lasers, krypton-ion lasers, helium / cadmium lasers, which emit between 300 and 600 nm, but for some layers also CO₂ lasers, which are at 10.6 µm emit, or YAG lasers that emit at 1.06 µm.

Neutral or alkaline aqueous solutions with a pH in the range from 6 to 14, preferably 7.5 to 12, are used as developers, the buffer salts, e.g. B. water-soluble alkali metal phosphates, silicates, borates, carbonates, acetates or benzoates. Wetting agents, preferably anionic wetting agents, and optionally water-soluble polymers are used as further constituents. The solution can also contain small amounts, e.g. B. up to 5, preferably not more than 2 wt .-% of water-miscible organic solvents. Low volatility solvents, e.g. B. araliphatic alcohols, the vapor pressure of which is negligible when handling the developer.

Development can be carried out in a known manner by dipping, spraying, brushing or tamping.

The binders containing urethane and carboxyl groups used according to the invention can be produced easily and reproducibly. They have good compatibility with other layer components and can be easily combined with one another and with other polymers to form homogeneous layers.

The layers are not sensitive to scratching, can be easily developed with aqueous alkaline solutions and result in a very good differentiation between image and non-image areas and a steep gradation.

Of particular advantage is the unusually long print run, which is achieved with the printing forms made from the material according to the invention, and the good ink acceptance. The stencils are also highly resistant to alkaline developers.

Another advantage is the very good tonal value reproduction of the layers as well as their unusually low susceptibility to radiation. In addition, the mixtures and recording materials according to the invention have an excellent shelf life.

The following examples are intended to illustrate the invention. Parts by weight and parts by volume are in the ratio of g / ccm, percentages and proportions are to be understood in units of weight unless otherwise stated.

example 1

40 pbw of a polyvinyl butyral with a molecular weight of about 70,000 to 80,000 and containing 71% vinyl butyral, 2% vinyl acetate and 27% vinyl alcohol units are dissolved in 700 pbw of methyl ethyl ketone with heating. 0.4 pbw of diazabicyclo [2.2.2] octane are added to the clear solution. Then 5 pbw of butyl isocyanate are added dropwise. The mixture is heated to reflux for 4 hours. A residual isocyanate determination carried out at this point shows that the reaction has practically been quantitative. Now it is cooled to 50 ° C., 1.2 pbw of triethylamine and then 5 pbw of maleic anhydride are added in one portion. The mixture is refluxed for another 5 hours. After cooling, the solution is added dropwise to 10,000 pbw of distilled water, a fibrous, white material being obtained. This is filtered off and dried in vacuo at 40 ° C.
Yield: 47 pbw
Analysis: C 61.8%; H 9.4%; N 0.42%
Acid number: 43.

A coating solution
31 pbw of the polymer described above,
10.5 pbw of a diazonium salt polycondensation product, prepared from 1 mol of 3-methoxy-diphenylamine-4-diazonium sulfate and 1 mol of 4,4'-bis-methoxymethyl-diphenyl ether in 85% phosphoric acid and isolated as mesitylene sulfonate,
2.0 pbw of phosphoric acid (85%),
1.5 Gt Victorian Pure Blue FGA (CIBasic Blue 81) and
0.3 pbw of phenylazodiphenylamine in
1400 pbw of ethylene glycol monomethyl ether and
320 pbw tetrahydrofuran
is applied to an aluminum foil, which is roughened by brushing with an abrasive suspension, then anodized and then pretreated with a 0.1% aqueous solution of polyvinylphosphonic acid, and then dried.

The light-sensitive layer thus obtained, which has a layer weight of 0.92 g / m 2, is exposed under a standard negative original for 18 seconds with a metal halide lamp of 5 kW output.

The exposed layer shows a clear contrast between the exposed and unexposed areas and is made with a developer solution of the following composition:
5.0 pbw of sodium octyl sulfate,
1.5 pbw of sodium metasilicate x 5 water,
1.5 pbw of trisodium phosphate x 12 water,
0.5 pbw of disodium hydrogen phosphate x 12 water,
91.5 pbw of demineralized water
treated with a plush tampon, the unexposed layer areas within a short time be removed clean, and then rinsed with water and dried.

In the copy, stage 4 of a halftone step wedge with a density range of 0.15 to 1.50 and density increments of 0.15 is fully covered. The printing plate obtained in this way delivers a print run of 95,000 sheets on a sheetfed offset press.

Example 2

25.3 pbw of a copolymer of styrene and allyl alcohol, which contains 46% styrene and 54% allyl alcohol units and has an OH number of 420, is dissolved in 402 pbw of methyl ethyl ketone. A solution of 2.5 pbw of methyl isocyanate and 0.1 pbw of diazabicyclo [2.2.2] octane is added dropwise to the clear solution. When the addition is complete, the mixture is slowly heated to the reflux temperature. After about 3 hours, the mixture is allowed to cool to 50 ° C. and a solution of 3 pbw of phthalic anhydride and 0.3 pbw of triethylamine in 20 pbw of methyl ethyl ketone is metered in. The mixture is heated to reflux for a further 5 hours and, after cooling, is added dropwise to 10,000 pbw of demineralized water, a very fine-grained but easily filterable white powder being obtained, which is filtered off with suction and dried as described in Example 1.
Yield 28 pbw
Analysis 0.8% N
Acid number 35.

A coating solution
86.5 pbw of the binder described above,
29 pbw of the diazonium salt polycondensate described in Example 1,
3.5 pbw of phosphoric acid (85%),
4.3 Gt Victorian pure blue FGA and
1 pbw of phenylazodiphenylamine in
4000 pbw of ethylene glycol monomethyl ether
is applied to an aluminum foil which has been electrochemically roughened in nitric acid, then anodized and aftertreated with polyvinylphosphonic acid. The dry layer weight is 0.9 g / m².

The exposure is carried out as indicated in Example 1, while developing a mixture
25 pbw of salicylic acid and
75 gt water
used, which has been brought to a pH of about 8 with ethylenediamine.

After inking, a printing form is obtained which is good in terms of color and the non-image areas of which do not assume a bold color. When you run a sheetfed offset press, you get a few thousand good prints.

Example 3

36.4 pbw of the polyvinyl butyral described in Example 1 are reacted with 8.5 pbw of ethyl isocyanate and 3 pbw of maleic anhydride in accordance with the instructions given there. The precipitated polymer has an acid number of 21 and has a carbon content of 61.1%, a hydrogen content of 9.4% and a nitrogen content of 1.0%.

A coating solution
20 pbw of the polymer described above,
20 pbw of the diazonium salt polycondensation product described in Example 1,
2 pbw of phosphoric acid (85%),
2 Gt Renol Blue B2G-HW (CI 74160) and
0.2 pbw of phenylazodiphenylamine in
1500 pbw of ethylene glycol monomethyl ether
is applied to the carrier described in Example 2 by spinning. The layer weight of the dried layer is 1.0 g / m².

The exposure is carried out as indicated in Example 1. The development takes place within a very short time with a developer of the following composition:
21 pbw of sodium salicylate,
8 pbw of sodium tetrapolyphosphate,
4 pbw of trisodium phosphate x 12 water,
0.5 pbw of benzyl alcohol,
66.5 pbw of demineralized water
by rubbing carefully with a soft plush pad. The aluminum is exposed in the unexposed areas after just a few seconds.

The resultant, veil-free, steep gradation and high resolution printing form prints in a sheetfed offset press a print run of 210,000 sheets, without a significant wear of the copy being visible.

Example 4

56 pbw of the polyvinyl butyral described in Example 1 and 15 pbw of ethyl isocyanatoacetate and 9 pbw of phthalic anhydride are reacted in 980 pbw of methyl ethyl ketone with the addition of the corresponding catalysts as described in Example 1. After the precipitation, a white, fibrous polymer is obtained which has an acid number of 19 and a nitrogen content of 0.65%. The yield is about 65 pbw.

A coating solution
62 pbw of the above polymer,
21 pbw of the diazonium salt polycondensation product described in Example 1,
2 pbw of phosphoric acid (85%),
3 Gt Victorian Pure Blue FGA and
1 pbw of phenylazodiphenylamine in
2570 pbw of ethylene glycol monomethyl ether and
780 pbw tetrahydrofuran
is applied to an aluminum foil as described in Example 2 and then processed with a developer of the following composition:
5.0 pbw of sodium octyl sulfate,
1.5 pbw of sodium metasilicate x 5 water,
1.0 pbw of trisodium phosphate x 12 water,
1.5 pbw of phenoxyethanol,
91.0 pbw of demineralized water.

After just a few seconds of wiping with a plush pad, the non-image areas come off; it is rinsed with water and dried.

You get a very high quality copy, in which even the finest elements of the template are reproduced exactly. The ink takes on unusually quickly when it is pressed. With a sheetfed offset press, 240,000 high-quality prints are achieved.

Examples 5 to 9

The following examples are intended to compare the abrasion resistance of various light-sensitive mixtures with one another, the formulations differing in the binder components used.

Example 5: Resin A is a reaction product of the polyvinyl butyral described in Example 1 with phenyl isocyanate and maleic anhydride. It has an acid number of 40 (nitrogen content: 0.54%).

Comparative Example 6: Resin B is the reaction product of the polyvinyl butyral described in Example 1 with 3-oxaglutaric anhydride and has the acid number 50 (corresponds to Example 19 of DE-A 34 04 366).

Comparative Example 7: Resin mixture of resin B and resin C, which is a reaction product of equal molar amounts of 2,4-toluenediisocyanate and triethylene glycol.

Comparative Example 8: Resin D is a polymerization product of hydroxyethyl methacrylate, acrylonitrile and methyl methacrylate, then esterified with phthalic anhydride. It has an acid number of 32 (corresponds to example 8 of US Pat. No. 4,123,276).

Comparative Example 9: Resin Mixture of Resin C and Resin D.

Coating solutions of the following compositions are produced in parts by weight:

The solutions are filtered and each applied to a dry layer weight of 1.0 g / m² on an aluminum support which has been roughened electrolytically in nitric acid, anodized and aftertreated with polyvinylphosphonic acid.

The copying layers are exposed imagewise and processed with the developer described in Example 4. All layers can be developed quickly. While the layers of Examples 5 and 6 have a hard gradation, the gradation of the layer of Example 8 is softer and that of Examples 7 and 9 is extremely soft, making it difficult for them to assess the covered level of the test wedge. However, it is determined after thorough examination that all layers have a covered level 4 in the halftone step wedge.

The planographic printing plates obtained are clamped side by side in a sheetfed offset machine. All 5 plates quickly take on color. After long periods of inactivity, the ink acceptance of plates 7 and 9 is delayed.

In the case of plates 6 and 8, first outbreaks are observed in the screen areas at approximately 150,000 prints; plates 7 and 9, with the same assessment, achieve runs of up to around 190,000. The layer according to the invention of Example 5 is still intact even with a circulation of 230,000 sheets.

Example 10

A terpolymer which consists of 50% hydroxyethyl methacrylate, 20% methyl methacrylate and 30% hexyl methacrylate and has an average molecular weight of about 35,000 is, as described in Example 1, reacted with allyl isocyanate and maleic anhydride. The product has an acid number of 82.

A coating solution is prepared
3.5 pbw of the reaction product described above,
2.3 pbw of a diazonium salt condensation product, prepared by condensing 1 mol of 3-methoxy-diphenylamine-4-diazonium sulfate with 1 mol of 4-methyl-4ʹ-methoxymethyl-diphenyl ether and then with 1 mol of 4,4ʹ-bis-methoxymethyl-diphenyl ether in 85% phosphoric acid and precipitated as mesitylene sulfonate,
0.2 pbw of phosphoric acid (85%),
0.1 pbw of crystal violet (CI 42555) and
0.1 pbw of phenylazodiphenylamine in
160 pbw of ethylene glycol monomethyl ether.

After the processing described in Example 2, a printing form is obtained which has a print run of approximately 200,000.

If the exposed and developed printing form is treated with a stoving gum and heated to 220 ° C for 7 minutes, a print run of well over 270,000 prints is achieved.

Examples 11 to 15

The layers described in Examples 5 to 9 are tested for their shelf life. For this purpose, 5 plates are produced from each light-sensitive mixture and these are heated to 100 ° C. in a drying cabinet for 1 to 4 hours. For comparison, the fifth plate is not exposed to any heat storage. After the heat storage, the plates are exposed imagewise and developed with the developer described in Example 4. The dried plates are colored with protective paint to make the remaining layer residues visible in the non-image areas.

All plates containing a pure resin component (Examples 5, 6 and 8) can be developed perfectly after two hours of heat storage. The layer of Example 8 shows a clear extension of the halftone step wedge. The layers containing resin mixtures (Examples 7 and 9) already clearly tone after such a heat treatment.

After three hours of heat storage, the layer of Example 8 likewise shows the first sound tracks in the non-image areas, while those of Examples 5 and 6 have only a slight extension of the halftone step wedge.

The plates stored for four hours behave as follows: The planographic printing plate according to the invention of Example 11 (layer composition Example 5) can be developed with a delay, but without the formation of pancakes; the extension of the halftone step wedge is 4 steps. The comparative plate of Example 12 (layer composition Example 6) can be developed flat. The comparison plate of example 14 (layer composition example 8) shows strong clay and is no longer usable, the comparison plates of examples 13 and 15 (layer composition examples 7 and 9) can no longer be developed. In the combination of storage stability and abrasion resistance, the mixture according to the invention is thus clearly superior to the comparison mixtures.

Example 16

A monoisocyanate containing urethane groups is prepared from 1,6-diisocyanato-hexane and ethanol. It is obtained in a purity of 97% by distillation in a high vacuum. 20 pbw of the polyvinyl butyral described in Example 1 are dissolved in 300 pbw of dioxane and 6 pbw of the above isocyanate are added with the addition of 0.3 pbw of diazabicyclo [2.2.2] octane. The mixture is heated to 80 ° C. for 5 hours and then refluxed with a mixture of 4 pbw of trimellitic anhydride and 0.5 pbw of triethylamine for 5 hours. The cooled solution is dropped into distilled water. The dried polymer has an acid number of 53 and a nitrogen content of 1.2%.

A coating solution is made from
1.8 pbw of the polymeric reaction product described above,
1.8 pbw of the diazonium salt polycondensation product described in Example 1,
0.2 pbw of phosphoric acid (85%),
0.1 Gt Victorian Pure Blue FGA and
0.06 pbw of phenylazodiphenylamine in
150.0 pbw of ethylene glycol monomethyl ether.

The solution is applied to an electrochemically roughened and anodized aluminum foil which has been post-treated with polyvinylphosphonic acid and dried to a dry layer weight of 0.73 g / m 2.

The processing is carried out in a similar manner to that given in Example 3. The development is rapid and there is no residual veil in the non-image areas.

In the sheetfed offset press, the printing form immediately takes on bold color and a print run of more than 240,000 sheets is achieved.

Example 17

The coating solution described in Example 1 is spun onto the support described in Example 2. The layer weight after drying is about 1 g / m². Four plates of this type are stored in a tropical cabinet, which is heated to 40 ° C and has a relative humidity of 60%. One plate at a time is removed after 3, 6, 9 and 12 months, exposed imagewise and developed as described in Example 1. For comparison, a plate not exposed to these conditions is used, which has a covered step 4 in the halftone step wedge when exposed for 25 seconds.

The plates stored for 3 and 6 months correspond perfectly to the original plate. They can also be developed quickly and free of fog. The plate, which was stored for 9 months, shows a half-tone step wedge extension by not quite one step; however, their development is as rapid as that of the comparison sample. The plate stored for one year shows an extension by one step; their developability is practically not delayed. All plates are printed in a printing press and show no difference in terms of color acceptance or tint compared to the comparison plate.

Examples 18 and 19

It becomes a coating solution of the following composition
385 pbw of an 8% solution of the polymer described in Example 1 in methyl ethyl ketone,
12 pbw of the diazonium salt polycondensation product described in Example 1,
2 pbw of phosphoric acid (85%),
1 pbw of crystal violet (CI 42 555) and
0.4 pbw of phenylazodiphenylamine in
1350 pbw of ethylene glycol monomethyl ether
applied to an aluminum support which had been electrolytically roughened in hydrochloric acid, anodized and aftertreated with polyvinylphosphonic acid to a dry layer weight of 1.02 g / m 2 (Example 18).

For comparison, a mixture of appropriate composition is applied to the carrier described above, which differs in that as a polymer
385 pbw of an 8% solution of the reaction product from the polyvinyl butyral described in Example 1 with maleic anhydride in methyl ethyl ketone (acid number of the precipitated polymer 38) in accordance with DE-A 34 04 366
be used. The layer weight of this mixture after drying is 1 g / m² (comparative example 19).

Both plates are exposed and processed with the developer described in Example 1.

When clamping in a sheetfed offset press, 295,000 prints are achieved with the recording material according to the invention, while the recording material of the comparative example already shows clear signs of wear from 240,000 prints.

Example 20

Aluminum plates coated in accordance with Example 18 are stored unexposed in a hot cabinet which has a temperature of 56 ° C. for 2, 6, 13 and 26 weeks. After each removal, the plates are exposed and developed as described in Example 1.

It can be seen that the heat-stored plates show practically no delay in developability even after 26 weeks. The copy corresponds to the standard of example 18, whereby even the finest lines and picture elements of the original are flawlessly resolved.

The recording material of the invention is therefore very little sensitive to heat, so that elevated temperature, as can sometimes occur with improper storage, do not damage the material.

In Examples 21 to 24 below, the polyvinyl butyral described in Example 1 is reacted with different compositions of monoisocyanates and anhydrides. The reaction products obtained are processed in coating solutions in accordance with Example 18. In all cases, print runs of between 250,000 and 300,000 sheets are achieved.

Example 21

20 pbw of polyvinyl butyral are reacted with 3 pbw of n-hexyl isocyanate and 3 pbw of maleic anhydride. Acid number of the polymer: 32.

Example 22

20 pbw of polyvinyl butyral are reacted with 2.5 pbw of cyclohexyl isocyanate and 3 pbw of succinic anhydride. Acid number of the polymer: 28.

Example 23

20 pbw of polyvinyl butyral are reacted with 2 pbw of methyl isocyanate and 3 pbw of trimellitic anhydride. Acid number of the polymer: 47.

Example 24

20 pbw of polyvinyl butyral are reacted with 3 pbw of allyl isocyanate and 3 pbw of 3-oxaglutaric anhydride. Acid number of the polymer: 33.

In Examples 25 to 28 below, different hydroxyl-containing polymers are included a combination of 3 pbw of phenyl isocyanate and 3 pbw of maleic anhydride. The reaction products obtained are tested in formulations corresponding to Example 18. Depending on the starting polymers used, print runs of between 120,000 and 350,000 result, with the reaction products with polyvinyl acetals giving the best copying properties and the highest runs.

Example 25

20 pbw of a terpolymer of 91% vinyl chloride, 3% vinyl acetate and 6% vinyl alcohol are used. The reaction product has an acid number of 22. The circulation is 145,000 sheets.

Example 26

20 pbw of a polyvinyl butyral with an average molecular weight of 70,000-80,000 and 79% vinyl butyral, 2% vinyl acetate and 19% vinyl alcohol units are used. The acid number of the reaction product is 30. The print run is 350,000 sheets.

Example 27

20 pbw of a copolymer of 45% styrene, 7.5% methyl methacrylate, 38% hydroxyethyl methacrylate and 9.5% acrylonitrile with an OH number of 170 are used. The acid number of the reaction product is 30, the print run achieved 210,000.

Example 28

20 pbw of a polyvinyl formal with a molecular weight of 25,000 to 30,000 are used, which contains 68% vinyl formal, 25% vinyl acetate and 7% vinyl alcohol units. The acid number of the reaction product is 24, the print run achieved 285,000.

Examples 29 and 30

A coating solution of the following composition is applied to an aluminum plate which has been electrolytically roughened in nitric acid, anodized and aftertreated with polyvinylphosphonic acid to a dry layer weight of 1.0 g / m 2 (Example 29):
22 pbw of a reaction product of the polyvinyl butyral, methyl isocyanate and maleic anhydride described in Example 1 with a nitrogen content of 0.8% and an acid number of 40,
22 pbw of the diazonium salt polycondensation product described in Example 10,
1.9 pbw of phosphoric acid (85%),
2.6 pbw of Renolkarmin FBB-HW (CI Pigment Red 146) and
0.9 pbw of phenylazodiphenylamine in
1500 pbw of ethylene glycol monomethyl ether.

For comparison, a coating solution of the following composition is applied to the same support with the same layer thickness (Comparative Example 30):
22 pbw of a reaction product of the polyvinyl butyral described in Example 1 with propionic acid chloride and maleic anhydride (acid number 38),
22 pbw of the diazonium salt polycondensation product described above,
1.9 pbw of phosphoric acid (85%),
2.6 pbw of Renolkarmin FBB-HW (CI Pigment Red 146),
0.9 pbw of phenylazodiphenylamine in
1500 pbw of ethylene glycol monomethyl ether.

The intensely red-colored plates are exposed imagewise for 20 seconds under a test template and processed with a developer of the following composition by wiping with a plush pad:
0.1 pbw sodium metasilicate x 9 water,
3.9 pbw of disodium hydrogen phosphate x 12 water,
3.4 pbw of trisodium phosphate x 12 water,
1.5 pbw of potassium tetraborate x 4 water,
2.0 pbw of potassium oxalate x 1 water,
2.5 pbw of sodium benzoate and
2.0 pbw of sodium octyl sulfate in
84.6 pbw of demineralized water.

Both plates can be developed quickly and without fog, and the finest elements of the test template are reproduced.

When printing in a sheetfed offset machine, 315,000 flawless prints are achieved with the planographic printing plate according to the invention, while the comparison plate already shows signs of wear from 200,000 prints and can no longer be used from 260,000 prints.

Claims (10)

1. Photosensitive composition which contains a diazonium salt polycondensation product and a non-photosensitive polymeric binder with carboxyl side groups, which is soluble or at least swellable in aqueous-alkaline solutions and is a reaction product of an intramolecular anhydride of an organic polycarboxylic acid with a polymer containing hydroxyl groups and having no other functional groups capable of reaction with acid anhydrides, characterized in that the binder furthermore contains lateral substituents, containing urethane groups which have been formed by reacting organic monoisocyanates with hydroxyl groups of the polymer.
2. A photosensitive composition as claimed in claim 1, characterized in that the organic polycarboxylic acid is a di- or tricarboxylic acid.
3. A photosensitive composition as claimed in claim 2, characterized in that the acid anhydride is a compound of one of the formulae I, II and III

   

   where

   R¹ and R²   individually denote hydrogen atoms, halogen atoms or alkyl groups or are interconnected to form an aromatic or heteroaromatic, unsubstituted or substituted and optionally partially hydrogenated five-membered or six-membered ring which may be fused with up to two aromatic or cycloaliphatic rings,

   R³, R⁴ and R⁵   individually denote hydrogen atoms or alkyl groups or

   R³ and R⁵   are interconnected to form an unsubstituted or substituted saturated or unsaturated aliphatic ring which, inclusive of X, may have five or six ring members,

   R⁶ and R⁷   are hydrogen atoms or alkyl groups,

   X   is a single bond, a 1,1-alkylene group, a 1,1-cyclo-alkylene group, which are optionally substituted, an oxygen or sulfur atom,

   Y   is an oxygen or sulfur atom, a 1,1- or 1,2-alkylene group or a 1,2-alkenylene group, which may optionally be fused with an aromatic or cycloaliphatic ring, and

   Z   stands for the ring members required for the completion of a saturated or unsaturated, unsubstituted or substituted ring, it being possible for this ring to be fused with up to two aromatic or cycloaliphatic rings.
4. A photosensitive composition as claimed in claim 1, characterized in that the monoisocyanate corresponds to one of the formulae IV and V
   
   
   
           R^a - NCO   (IV)   R^c-O-CONH-R^b-NCO   (V)
   
   
   
   where

   R^a and R^c   are unsubstituted or substituted alkyl, alkenyl or aryl groups and

   R^b   is an unsubstituted or substituted alkylene, cycloalkylene, arylene or arylene-alkylene group.
5. A photosensitive composition as claimed in claim 1, characterized in that the polymer containing hydroxyl groups is a polyvinyl acetal, a polyvinyl acetate having free hydroxyl groups or a copolymer of a hydroxyalkyl acrylate or methacrylate.
6. A photosensitive composition as claimed in claim 1, characterized in that the binder contains from 1 to 15 % by weight of urethane groups.
7. A photosensitive composition as claimed in claim 1, characterized in that the binder has an acid number from 10 to 120.
8. A photosensitive composition as claimed in claim 1, characterized in that the negative-working diazonium salt polycondensation product comprises recurrent units A-N₂Q and B, which are linked by intermediate members, preferably methylene groups, which are derived from condensible carbonyl compounds, A being the radical of an aromatic diazonium compound which is capable of condensation with formaldehyde and B being the radical of a compound which is free of diazonium groups and is capable of condensation with formaldehyde, particularly of an aromatic amine, of a phenol, phenol ether, aromatic thioether, of an aromatic hydrocarbon, of an aromatic heterocyclic compound or of an organic acid amide.
9. A photosensitive composition as claimed in claim 8, characterized in that the diazonium salt polycondensation product is a product having recurrent units A-N₂Q and B, which are linked by bivalent intermediate members derived from a carbonyl compound which is capable of condensation, the units A-N₂Q being derived from compounds of the general formula
   
   
   
           (R⁸-R⁹-)_pR¹⁰-N₂Q
   
   
   
   where

   Q   is the anion of the diazonium compound,

   p   is an integer from 1 to 3,

   R⁸   is an aromatic radical which is capable of condensation with an active carbonyl compound, in at least one position,

   R¹⁰   is an unsubstituted or substituted phenylene group, and

   R⁹   is a single bond or one of the groups:

   -(CH₂)_q-NR¹¹-
   -O-(CH₂)_r-NR¹¹-,
   -S-(CH₂)_r-NR¹¹-,
   -S-CH₂CO-NR¹¹-,
   -O-R¹²-O-,
   -O-,
   - S -, or
   -CO-NR¹¹-,
   where

   q   is a number from 0 to 5,

   r   is a number from 2 to 5,

   R¹¹   is a hydrogen atom, an alkyl group having from 1 to 5 carbon atoms, an aralkyl group having from 7 to 12 carbon atoms or an aryl group having from 6 to 12 carbon atoms, and

   R¹²   is an arylene group having from 6 to 12 carbon atoms, and

   B being the radical of an aromatic amine, phenol, thiophenol, phenolether, aromatic thioether, aromatic hydrocarbon, of an aromatic heterocyclic compound, or of an organic acid amide, which is free of diazonium groups.
10. Photosensitive recording material comprising a support and a photosensitive layer, characterized in that the photosensitive layer comprises a composition as claimed in claim 1.