DE2344680A1 - Photopolymerisable relief printing plates - copolymer of monounsatd. acids esters and nitroiles crosslinked by divinyl compounds - Google Patents

Abstract

Photopolymerisable mixts. comprise 50-80% copolymer (A), 20-50% polyfunctional monomeric crosslinker (B) and, optionally, inhibitors and sensitisers. (A) is prepd. by copolymerising 25-60%, pref. 35-50%, of aliphatic monounsaturated carboxylic acids or anhydrides with 3-12C atoms, 15-50% pref. 23-46% acrylonitrile and/or vinyl chloride, and 5-60% of >=1 monovinyl cpds. pref. acrylic esters and styrene. (B) consists of a diacrylate or dimethacrylate of a glycol or oligoether of a glycol, or other divinyl or diallyl cpds. The mixts. are used in the preparation of relief printing plates by UV light exposures through a negative to cure the polymer and washing away unexposed polymer. The unexposed, unpolymerised mixt. is readily dissolved by weak alkalies e.g. N/10 Na2CO3 aq. but the exposed polymer resists washing away. Organic solvents which are flammable,toxic and costly are not required for this etching process. The polymer mixt. coats metal plate efficiently and when cured and etched, the relief pattern accepts inks well and resists abrasive wear during printing.

Description

Patent attorney HvK / D (568)

Dr. Michael Hann 3rd September 1973

63 casting
Ludwigstrasse 67

Professor Dr. Bruno Vollmert, Karlsruhe

PHOTOPOLYMERIZABLE MIX AND USE IT FOR THE PRODUCTION OF RELIEF PRINT PLATES

The present invention relates to a photopolymerizable Mixture for the production of relief printing plates and their use for the production of relief printing plates.

It is known, printing plates by photopolymerization of Mixtures of polymers and polyunsaturated, polymerisier to produce monomers.

Films made from such mixtures become insoluble on exposure to UV light as a result of crosslinking photopolymerization, so that when you expose a film through a negative, the unexposed Parts can be washed out with solvents, whereas the exposed parts remain unchanged due to their insolubility stay back. To accelerate the polymerization in UV light these mixtures usually contain sensitizers. At the same time, however, they usually also contain inhibitors, which prevent undesired, premature polymerization during the preparation and storage of the mixtures.

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Numerous polymers and copolymers have been proposed for the preparation of such blends, such as z.3. Cellulose derivatives, polyamides, unsaturated polyesters, Vinyl chloride copolymers, polyethylene oxide, epoxy resins and the like. The use of such mixtures for the production of relief printing plates and the use of the printing plates themselves require certain properties with regard to the polymers, all of which require the usefulness of a polymer determine.

To be suitable, the polymers must meet the following requirements:

With polyunsaturated compounds, they should result in solutions or mixtures that are as homogeneous as possible. From these solutions or mixtures must be easy to produce, e.g. by casting, foils. These foils must not be sticky and should have good mechanical strength. The foils should be soluble in solvents so that the unexposed ones and non-crosslinked parts can be washed out. During photopolymerization, they should be crosslinked as homogeneously as possible deliver solid films. The latter must be able to be glued with metals. In addition, they should be abrasion-resistant and tough; If possible, they should not swell in printing inks, but should be easy to wet with the latter.

The unexposed parts of the photo relief plates are washed out with organic solvents, and it is disadvantageous that these solvents, such as acetone or !! ethanol, are easily flammable; in addition, their fumes are mostly poisonous. It is also disadvantageous that the washing solutions by a Distillation process must be worked up.

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It would therefore be desirable to have relief printing plates, whose unexposed areas are water or weakly Wash out alkaline} water.

It has now been found that this object in connection with the previously known properties of the invention Mixture and the method according to the invention solved will.

This photopolymerizable mixture of a copolymer, a polyunsaturated monomer and optionally polymerization inhibitors and sensitizers for the production of relief printing plates contains,

a) 50 to 80 parts of a copolymer of 25 to 60 wt.% of a copolymerizable unsaturated carboxylic acid-or anhydride thereof, 15 to 50 wt.% acrylonitrile and / or vinyl chloride and 5 to 60 wt. ° U one or more further Monoviny! compounds in polymerized form

b) 20 to 50 parts of a crosslinking monomer containing more than one polymerized double bond per molecule.

Component a) according to the invention can be prepared by free-radical copolymerization by the customary processes, for example by solution or emulsion polymerization. The solution here is particularly useful because it gets the CGpoI.71r.ere equal in eir.tr form in which it '..' else b easily with component mixed) and

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23U680

Manufacture of foils can be used.

Preferred unsaturated carboxylic acids are mono- and dicarboxylic acids with less than 12 carbon atoms, e.g. acrylic acid, ivathacrylic acid, Maleic acid, fumaric acid, itaconic acid and esters ozw. Amides of these acids with hydroxycarboxylic acids or aminocarboxylic acids. Other monovinyl compounds are e.g. styrene, acrylic ester, Methacrylic acid ester, butadiene, acrylamide, vinylpyrrolidone .. They are also used in amounts of 5 to 60% by weight, u ;;. the To be able to adapt the properties of the copolymers as precisely as possible to the application requirements from case to case. For example, by using styrene as well, the relief printing plates can be made more hard after exposure, using curd of acrylic esters and / or butadiene, on the other hand a higher one Flexibility that can go as far as the rubbery consistency of the foils or the exposed plates. Also the solubility can be achieved by using the Ccr.ionoraeren mentioned modify as desired. The solubility decreases one so from that on the one hand a sufficient solubility of the unexposed Parts in dilute alkali are guaranteed, on the other hand the exposed and thus networked parts as far as possible swell little during the washout process. The type and amount of the proportions of further monomers also depend above all on the type of component b). By modifying component a) it is possible to use other monovinyl compounds - w: _e preferably styrene or AcrylviStern - the compatibility with of component b) optimally set. After all, the

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Affinity of the printing plates for the inks used in printing can be influenced by using other monomers such as acrylamide. Particularly preferred further monomers for modifying component a) are styrene and acrylic esters, which can also be used as a mixture. Among the acrylic esters, those with 1 to 18 carbon atoms, preferably 1 to 8 carbon atoms in the alcohol radical, have proven useful for the production of versatile printing plates with balanced properties. Preferred acrylic esters are, for example, the acrylic esters of methanol, ethanol, propanol, n-butanol, 2-ethylhexanol and the acrylic esters of ether alcohols, for example ethylene glycol monomethyl ether, ethylene glycol monoethyl ether and the higher homologues of these compounds and also the higher ethoxylation products of ethanol, methanol or other alcohols . Preferred acrylic esters are also the monoacrylates of glycols, e.g. Ächylenglykolraonoacrylat, Bucandiolmonoacrylat, and the Konoacrylester of polyethylene glycols, for example of diethyienglykol, triethylene glycol and tetraethylene glycol. The Acrylester v / ground expediently in amounts of from 5 to 30 wt.%, Preferably from 10 to 20 wt.% Is used. Styrene kar.n in amounts of up to 0 to 60% by weight, preferably from 20 to 30 C sr- ;. / be used.

:. ie inventive component b), that is Vernetzar sawn ^ j ^ lc of compounds containing more than one polymerislerbare -V ~ y- ~ - contain · "education known Such compounds ijt, they del in the polymerization crosslinked polymers deliver Gaeiyae .. ^ Vgi \ jindungen dias'ar kind include, for example, _t diacrylate esters and DiniethacryL2s_er Oly / ICEN, Z.3. of ethylene glycol, propylene

O 0 9 B) ?. ! 0 ύ -j J

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glycol, butanediol or glycol ethers, such as diethylene glycol, triethylene glycol and tetra-ethylene glycol or acrylic or methacrylic esters of glycerol or pentaerythritol; Furthermore, Di- and TrialIy! connections, such as 3. Diallyl fumarate, triallyl cyanurate or diallyl esters of succinic acid _y adipic acid, sebacic acid; also divinylbenzene and acrylamides: from di- and triamines or acrylesteramides from aminoalkol'.olen, such as, for example, ethanolamine. These and analogous connections Ice on individually or in a mixture with one another with the component - mixed v / earth. Which compound or which combination.:ion of compounds of group b) is most suitable in each case depends on the composition of the copolymer a) and can easily be determined in each case by simple experiments.

A preferred class of compounds from the network Component b) is that of the oligoglycol ether diacrylates ur.a -dimethacrylates, e.g. tri- or tetraethylene glycol diacrylate or dimethacrylate, and mixtures of these Diacrylace raic other divinyl or diallyl compounds.

The Kcr.ponenfce b) canoe next to din Divinyl / erbindungen _ ^ c. subordinate manganese, for example 5 to 40% by weight monovinylvei., -..- contains; -. Preferred monovinyl compounds ε5 ^ those with low volatility and mi ^ Copv.-./^irisa-ior.oparamete ^.i (λ ir the chosen DivL-.vlvcrbradnng) near oe ,. I e.g. -vcrylesi; ... of higher * U '. * iols and ivcher alcohols with 4 to 12 ^ - ..

F 0 h ■ "::> ■ 'G η 3 2

BATH

In detail, the mixture of components a) and b) can be prepared in various ways, for example by mixing them directly in a kneader, in an extruder or on a roller mill, or - and this is the preferred form of mixing - by a solution of the copolymer a) in a solvent, for example in acetone, tetrahydrofuran, dioxane, ethyl acetate, dimethylformamide, N-methylpyrrolidone, cyclohexanone or mixtures of such solvents, with the polyunsaturated compound b) or mixtures of such compounds. From the solutions obtained in this way, homogeneous films can be obtained in a known manner after the casting process by evaporation or evaporation of the solvent (s), which after irradiation with UV light by a negative and washing out the unexposed parts with aqueous alkali (NaOH, KOH, Na ₂ CO ₃ , K ₂ CO ₃ ) give relief printing plates.

So that no premature, uncontrolled polymerization takes place during the mixing and evaporation process, inhibitors are generally added to the mixture of components a) and b). Such inhibitors are e.g. quinone, Hydroquinone, anthraquinone, benzthiazine, methylene blue, di-t-butyl-p-cresol. They are preferably used in the mixtures according to the invention in amounts of 0.02 to 5 parts per 100 parts of the Mixture of a) and b) used.

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So that, on the other hand, the fastest possible polymerization begins when exposed to a UV-rich light source, the photomerizable mixture are usually sensitizers, usually in amounts of 0.1 to 5 parts to 100 parts of the mixture from a) and b). The addition of sensitizers makes the photopolymerization accelerated. Such compounds, which have been known for a long time, are z. B. azoisobutyric acid dinitrile, benzoin and benzoin ether, anthraquinone and its derivatives. Anthraquinone is particularly suitable because it is a normal one Polymerization prevents or delays photopolymerization but favored; so it is an inhibitor and sensitizer at the same time.

In addition to the sensitizers, dyes can be added to the photopolymerizable mixtures according to the invention preferably those that form radicals on exposure,

Some photopolymerizable mixtures according to the invention and their preparation and use are described in more detail in the following examples.
The quantities given are parts by weight.

example 1

70 parts of acrylic acid, 30 parts of acrylonitrile, 40 parts of styrene, 20 parts of methyl acrylate, 300 parts of dimethylformamide and 0.5 part of azodiisobutyric acid dinitrile are copolymerized at 70 ° C. with stirring, reflux cooling and the exclusion of oxygen. After 7 hours, the polymerization is terminated by cooling and adding 2 parts of anthraquinone and 1 part of di-tert-butyl-p-cresol. Evaporation of a sample of the polymer solution in vacuo results in a polymer residue of 26% by weight , from this

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a conversion of 75% is calculated b. .. sucked on the used Total amount of monomer

The solvent-free copolymer has the following composition;

32.0 Ge./. % Acrylic acid, 24 _y 9 wt.% Acrylonitrile, ■ 29.7 wt.% Styrene, 13.4 wt.% Methyl acrylate.

The remaining ionomer and 60 parts of dimethylformamide are distilled off from the polymer solution at 15 torr, so that a pause of about 360 parts remains. Then 50 parts of Tetraachyienglykolcijüauhacrylat are added and mixed in homogeneously. 24 parts of this mixture are drawn out evenly using a film-drawing device on a flat, grease-free 10 × 10 cm aluminum plate which has been coated with a spoxy resin-hardener mixture and pretreated at 70 ° C. for 25 minutes. The aluminum plates coated in this way are dried for 3 hours at 50 ° C. in a dark drying cabinet while passing a gentle stream of air over them. The drying cabinet is then placed under slowly increasing vacuum such that a vacuum of 15 torr is reached after 3 hours. The plates are then dried for a further hour at 50 C and 15 Torr. This gives an aluminum space coated with an approximately 1 mm thick photopolymerizable layer. In the unexposed state, the layer is _{soluble in n / 10 Na 2} CO solution, but becomes so insoluble on brief exposure to UV light that it is _{not attacked by n / 10 Na 2} CO ₃ solution during the washing process of the unexposed parts will.

Example 2

120 parts of acrylic acid, 60 parts of acrylonitrile, 60 parts of styrene, 30 parts of methyl acrylate, 400 parts of dimethylformamide and 0.8 parts of azodiisobutyronitrile are equal

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Way as described in Example 1 copolymerized. After 5 hours, the polymerization is terminated by cooling and adding 3.17 parts of anth.rach.inone and 1.6 parts of di-tert-butyl-p-cresol. Evaporation of a sample of the polymer solution in vacuo results in a polymer residue of 23% by weight . A conversion of 70% based on the total amount of monomer used is calculated from this. ·

The solvent-free copolymer has the following composition:

35.0 wt.% Acrylic acid, 27.0 wt.% Of acrylonitrile, 27.0 wt.% Styrene, 11.0 wt.% Methyl acrylate. About 100 parts of volatile constituents are distilled off from the polymer solution in vacuo (15 torr), so that a residue of about 570 parts remains. After adding 80 parts of tecraethylene glycol dimethacrylate, a mixture is obtained which Evaporation of the solvent provides flexible films which, as described in Example 1, can be processed into photographic printing plates with high mechanical strength, the unexposed portions of which are soluble in 1/10 normal sodium hydroxide solution,

Example 3

70 parts of acrylic acid, 50 parts of acrylonitrile, 20 parts of methyl acrylate, 0.5 parts of azodiisobutyric acid dinitrile and 200 parts of dimethylformamide are prepared in the same way as in Example 1 described, copolymerized. After 7 hours it will the polymerization was terminated by cooling and adding 1.3 parts of anthraquinone and 0.6 parts of di-tert-butyl-p-cresol. Evaporation of a sample of the polymer solution in vacuo results in a polymer residue of 23% by weight. From it a conversion of 57% based on the amount used is calculated

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BATH ORIGINAL

Total amount of money.

The composition of the dry matter is:

48.0 wt.% Acrylic acid, 42.0 wt.% Of acrylonitrile, 10.0 wt.% Methyl acrylate.

After 70 parts of the polymer solution have been distilled off and 33 parts of tetraethylene glycol dimethacrylate have been added, a mixture is obtained which, after the solvent has evaporated, yields flexible, non-adhesive films which can be processed into photographic printing plates as described in Example 1. In the unexposed state, the films are soluble in n / 10 sodium hydroxide solution and become insoluble after exposure to UV light and take on a tough, hard consistency. As a result of their high acrylonitrile content, these printing plates are particularly resistant to printing inks.

Example 4

70 parts of acrylic acid, 70 parts of acrylonitrile, 20 parts of methyl acrylate, 0.5 part of azodiisobutyric acid dinitrile and 200 parts of dimethylformamide are copolymerized in the manner described in Example 1 for 7 hours. After 40 parts of liquid constituents have been distilled off, the polymerization is terminated by adding 2 parts of anthraquinone and 0.9 parts of di-tert-butyl-p-cresol. The polymer residue after evaporation of a sample is 35%. The conversion calculated from this is 78 %. The composition of the dry matter is:

38.0 wt.% Acrylic acid, 46.0 wt.% Of acrylonitrile, 16.0 wt.% Methyl acrylate.

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After adding 50 parts of butanediol diacrylate, a film is obtained which, as described in Example 1, turns into photographic printing plates can be processed. The properties of the film are the same as those described in Example 3.

The relief printing plates obtained from the mixtures according to the invention are characterized by high mechanical strength, good homogeneity and good wettability by printing inks. The elimination of their unexposed parts by dilute aqueous alkalis is associated with substantial savings and a reduction in the risk of accidents.

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Claims (10)

Claims Γ 1.'Photopolymerizable mixture of a copolymer, a polyunsaturated monomer and optionally polymerization inhibitors and sensitizers for the production of relief printing plates, characterized in that that the mix a) 50 to 80 parts of a copolymer of 25 to 60 wt.% of a copolymerizable unsaturated carboxylic acid or anhydride thereof, 15 to 50 wt.% acrylonitrile and / or vinyl chloride and 5 to 60 wt.% of one or more further Monovxnylverbindungen in polymerized form and b) 20 to 50 parts of a crosslinking, more than one polymer contains isable double bond per molecule containing monomers. 2.Photopolymerizable mixture according to claim 1, characterized characterized in that the copolymer 35 to 50 wt.% Of a aliphatic monoolefin mono- or dicarboxylic acid with Contains 3 to 12 carbon atoms or their anhydride. 3. A photopolymerizable mixture according to claims 1 or 2, characterized in that the copolymer contains 23 to 46 wt.% Acrylonitrile. 509BT2 / (K92 4. Photopolymerizable mixture according to one of claims 1 to 3, characterized in that the copolymer 10 to 20% by weight of acrylic esters of saturated alcohols
or of ether alcohols with 1 to 8 carbon atoms. 5. Photopolymerizable mixture according to one of claims 1 to 3, characterized in that the copolymer Contains 20 to 30% by weight of styrene. 6. Photopolymerizable mixture according to one of claims 1 to 3, characterized in that the copolymer
contains a mixture of acrylic ester and styrene. 7. Photopolymerizable mixture according to one of the claims 1 to 6, characterized in that the polyunsaturated, crosslinking monomer is a diacrylic and / or -dimethacrylic ester of a glycol. 8. Photopolymerizable mixture according to one of the claims 1 to 6, characterized in that the polyunsaturated, crosslinking monomer is an oligoglycol ether diacrylate and / or dimethyl acrylate. 9. Photopolymerizable mixture according to one of claims 1 to 6, characterized in that the polyunsaturated, crosslinking monomer is a mixture of one
Oligoglycol ether diacrylate with other divinyl or dial IyI is verb indungen. 509812/0492 10. Use of the photopolymerizable mixtures according to one of claims 1 to 9, for the production of relief Printing plates with washing out of the unexposed parts with aqueous alkalis. 509812/0492