GB2198741A

GB2198741A - Photopolymerisable materials

Info

Publication number: GB2198741A
Application number: GB08630358A
Authority: GB
Inventors: Norbert Kraus; Dr Uwe Muller; Klaus Rittmeier; Prof Dr Manfred Ratzsch; Dr Barbara Wohlfahrt; Prof Dr Hans-Joachim Timpe; Prof Dr Horst Bottcher; Dr Aniela Leistner; Dr Harald Baumann; Prof Dr Herward Pietsch
Original assignee: Filmfabrik Wolfen VEB
Current assignee: Filmfabrik Wolfen VEB
Priority date: 1984-04-03
Filing date: 1986-12-19
Publication date: 1988-06-22
Also published as: DD250593A1; FR2609186A1; DE3641687A1; CH669053A5; GB8630358D0

Abstract

A photopolymerisable material has a light-sensitive layer that comprises a maleic anhydride copolymer modified by hydrolysis or by converting the anhydride units to semi-ester, -imide or -amide form and having an average molecular weight of from 20,000 to 500,000 which on exposure and development coagulates and forms polyelectrolyle complexes. The layer generally also includes an unsaturated, polymerisable compound having at least one amino group capable of forming a salt with a carboxy group of the modified copolymer. The photopolymerisable material may be used for recording information, especially in the form of reproduction material.

Description

Photopolymerisable material The invention relates to photopolymerisable materials suitable for recording information, especially in the form of reproduction materials.

Photopol#ymerisable compositions and photopolymerisable materials have been described that consist of a polymer having salt-forming groups, an ethylenically unsaturated addition-polymerisable monomer containing at least one complementary salt-forming group, and an initiator that can be activated by light.

There are used as polymers containing salt-forming groups those in which the salt-forming groups are acidic groups, that is to say carboxylic, phosphoric and sulphonic acid groups, carbonate, sulphate and phosphate groups, or basic groups, for example primary, secondary and tertiary amino groups.

The unsaturated monomer component in the photopolymerisable composition then contains a corresponding complementary salt-forming group (US-PS 2 893 868, DE-OS 2 816 774).

Light-sensitive layers that contain polymer or monomer components with quaternary ammonium groups are described in US-PS 3 578 458.

The system of polyacrylate and Q-methacryloylethyl- trimethylammonium methyl sulphate described in US-PS 2 893 868 is polymerised only in solution.

A further possible method of obtaining ionically cross-linked polymers is proposed in US-PS 3 578 458 in which the unsaturated zwitterion 4-vinylpyridine-Nbutyl sulphobetaine is used.

t large number of compounds have been described as free radical-forming systems that can be activated by actinic radiation and that trigger polymerisation of the unsaturated monomer component. There may be mentioned as examples: aromatic ketones, for example benzophenone, Michler's ketone, benzoin, benzoin ethers, for example benzoin methyl ether (US-PS 2 893 868, DE-OS 2 816 774) and 2,4,5-triarylimidazolyl dimers, for example 2-(ochlorophenyl)-4,5-diphenylimidazole dimers (US-PS 3 479 185, US-PS 3 784 557). Various dyes, for example Bengal pink and eosin Y (US-PS 3 578 58) may also be used. A very wide variety of natural or synthetic materials have been described as support materials for photopolymerisable materials.The support materials can be produced in the form of flexible or rigid sheets or plates, for example copper, aluminium with a coating of aluminium oxide, silicon wafers, oriented polyester films, glass, laminated papers. When using synthetic polymer films, it is necessary for there to be additional adhesive layers on the support and for adhesion-improving additives to be present in the casting solution. As described in US-PS 2 893 868, layers that become insoluble as a result of the action of light are imagewise exposed and then developed. Generally, the unexposed parts of the layer are in addition removed, preferably by washing out with a solvent.There are described as solvents for this purpose a large number of organic compounds: cyclic ethers, for example dioxan, ketones, for example acetone, alcohols, for example methanol, esters, for example propyl acetate, aromatic compounds, for example toluene, and chlorinated hydrocarbons, for example dichloromethane: these solvents are used on their own or in admixture. In some cases water may be added to those organic solvents with which it is miscible . For some materials water and diluted aqueous organic and inorganic acids and bases, for example acetic acid and hydrochloric acid, ammonium, alkali metal and alkaline earth metal hydroxides, carbonates and bicarbonates, are mentioned as solvents After development colourless relief images are obtained, which are used, for example, as printing formes.To obtain readily visible images, dyes or pigments (for example carbon black) must be embedded in the light-sensitive layer, or the exposed, cured areas of the layer must be coloured in the developed material.

Generally, steps must be taken to protect the light-sensitive layer against the inhibiting action of oxygen, for example exposure to light in vacuo, or use of a coating that acts as a barrier layer to oxygen, for example a polyvinyl alcohol layer.

In DE-OS 2 816 774 protection against oxygen is unnecessary as a result of the use of very thin layers (= 25.4um) of an ionically cross-linkable photopolymerisable material. The material has a low sensitivity and poor adhesion to a PETP (polyethylene terephthalate) support.

The aim of the invention is to develop a photopolymerisable material suitable for recording information that is distinguished by very good adhesion of the areas of the light-sensitive layer that have been irradiated with actinic light and by making possible the use of simple procedures for development and for the rendering the image visible.

In accordance with the present invention there is provided a photopolymerisable material which gives a good contrast between exposed and unexposed areas after development without additional steps for making the image visible and of which the exposed cross-linked components adhere very well to the support.

The present invention provides a photopolymerisable material comprising a light-sensitive layer that comprises a modified maleic anhydride copolymer having salt-forming groups and having an average molecular weight of from 20,000 to 500,000.

Preferably, the light-sensitive layer comprises an ethylenically un#saturated monomer having at least one group capable of acting as a complementary salt-forming group with respect to the salt-forming groups of the copolymer.

Advantageously the modified maleic anhydride copolymer is an alternating copolymer, especially a modified alternating maleic anhydride/styrene copolymer, and the light-sensitive layer further comprises a modified non-alternating maleic anhydride copolymer of average molecular weight of from 10,000 to 300,000, having salt-forming groups and containing'60 to 95 mole % of a comonomer, the amount of the modified alternating maleic anhydride copolymer being 20 to 95% of the total maleic anhydride copolymer content of the layer.

The binder or the binder mixture (that is, the modified maleic anhydride polymer or mixture of modified maleic anhydride polymers) is dissolved in a solvent or solvent mixture, preferably aliphatic C1-C8 alcohols, together with at least one ethylenically unsaturated addition-polymerisable monomer, at least one monomer containing at least one primary, secondary or tertiary amino group, and with an initiator system that can be activated by actinic radiation in the range of from 200 to 800 nm to initiate the polymerisation, and contains at least one compound with a molar extinction coefficient of at least 50 when irradiated in the range of from 200 to 800 nm . The solution is cast onto a support, preferably biaxially stretched PETP film, and dried to an optically clear transparent film with a layer thickness of t 30 um.The material is image-wise exposed with actinic radiation in the range of from 200 to 800 nm, as a result of which polymerisation of the ethylenically unsaturated addition polymerisable monomer is triggered by means of the initiator system and an ionically crosslinked polymer is formed with the binder. The development is carried out by dissolving out the unexposed parts of the layer with water, an aliphatic C 1C4 alcohol or an aqueous solution.

Surprisingly it was found that with modified alternating maleic acid anhydride copolymers having several salt-forming groups and a mean molar mass of from 20,000 to 500,00, preferably, 80,000 to 250,000 as binder, and a thickness of the light-sensitive layer of =30 urn, the ionically cross-linked polymer formed coagulates during the development step and consequently there is a pronounced clouding of the exposed areas of the layer. A clearly recognisable opaque image is obtained which when projected has an excellent black/ white contrast as a result of the light scatter at the coagulated polymer particles. If, in addition, a modified non-alternating maleic acid anhydride copolymer with several salt-forming groups and a mean molar mass of from 10,000 - 300,000 and 60-95 mole E comonomer are used as a binder constituent in an amount of from of 5 to 80E of the total binder mixture the physico-mechanical properties of the layer, especially the adhesive property, and the drying behaviour after casting, are substantially improved, and the colouring of the exposed areas of the layer can be carried out more quickly and to higher colour densities.If there is used an initiator system that is especially suitable for such materials for example , one that consists of an H-donor, preferably Michler's ketone, an H-acceptor, preferably benzophenone, and one or more 'onium compounds, preferably iodonium compounds, then monomers having at least one primary, secondary or tertiary amino group as H-acceptors may also act as a component of the initiator system and cause a surprisingly high increase in sensitivity.

There may be used as comonomers for the manufacture of the modified alternating maleic acid anhydride copolymers used as binder any ethylenically unsaturated compound that together with maleic acid anhydride forms alternating copolymers, for example olefins, styrene, #-methylstyrene, vinyl acetate, alkylvinyl ethers.

There may be used as comonomers for the manufacture of the modified non-alternating maleic acid anhydride copolymers used as binder any ethylenically unsaturated compound that together with maleic acid anhydride forms non-alternating copolymers, for example acrylic and methacrylic compounds, styrene, vinyl acetate.

The modification of the maleic acid anhydride copolymers is in each case carried out by partial or complete hydrolysis and/or reaction with an aliphatic alcohol, preferably a q #-C8 alcohol, to form the semiester or with an aliphatic or aromatic amine, preferably a C1-C8 amine, or ammonia, to form the semiimide or amide respectively . The modification of the individual binder constituents may be carried out in the same or a different manner. One or more modification operations may be carried out on identical or different portions of the individual binder constituents.

There are used as monomers one or more ethylenically unsaturated addition-polymerisable compounds, of which at least one component contains one or more primary, secondary or tertiary amino groups, for example N,N'-dimethylaminopropyl acrylamide, N,N'diethylaminopropyl-ol-2-methyl acrylate, tris-(2-acryloyloxyethyl)amine. There may be used as comonomers other ethylenically unsaturated addition-polymerisable compounds, for example methylene bisacrylamide.

The ratio between the salt-forming groups of the binder and the salt-forming groups of the monomer shall be within the range of from 1 : 3 to 3 : 1.

There may be used as other additives in the light-sensitive layer inhibitors, for example hydroquinone monomethyl ether, for increasing storage stability, plasticisers, for example acrylate latices, and agents for protection against microorganisms.

After or during development the exposed areas of the layer can be coloured at room temperature, with a residence time of < 5 min., with light-fast dyes, for example Solamin light Turkish blue, methylene blue, Wofalan black, Walk brilliant red RS, densities > 1.5 in the absorption maximum of the respective colour being achieved.

The support may be coated with an adhesive layer.

Steps for protecting against the inhibiting effect of oxygen are not necessary.

In use, material according to the invention has a resolving power of 1 um uncoloured and 5 um coloured and an excellent edge definition, and there is complete absence of fogging. - Example 1 A mixture of 276 parts of styrene/maleic acid butyl semiester copolymer of a mean molar mass of 150,000, 156 parts of N,N-dimetbylaminopropyl acrylamide and 27 parts of benzoin sec.-butyl ether are dissolved in 316 parts of methanol and 1725 parts of n-butanol.

The layers are cast directly onto PETP film using a 0.25 mm doctor blade, and then dried. The dry layer thickness is 10 um. It is image-wise exposed for 60 seconds using high pressure mercury lamp HBO 200.

Development is carried out with a mixture of water/methanol (1:1) at room temperature over a period of not more than 30 seconds, A very good opaque image is obtained.

Example 2 A mixture of 237 parts of propylene/maleic acid butyl semiester copolymer of a mean molar mass of 35,000, 215 parts of 3-diethylamino-2-hydroxypropyl methacrylate and 51 parts of benzoin isopropyl ether are dissolved in 316 parts of methanol and 1665 parts of nbutanol and cast using a 0.25 mm doctor blade directly onto PETP sheet. The dry layer thickness is 8 um.

After 30 seconds' exposure analogously to Example 1, development with water is carried out over a period of less than 30 seconds at room temperature. A very good opaque image is obtained.

Example 3 A mixture of 268 parts of styrene/maleic acid anhydride copolymer of a mean molar mass of 110 000, 80 mole % of which has been reacted to form the butyl semiester and 20 mole % to form the methyl semiester, 171 parts of N,N-diethylaminomethyl acrylate and 54 parts of benzoin sec.-butyl ether are dissolved in 316 parts of methanol and 1725 parts of n-butanol, and cast using a 0.25 mm doctor blade directly onto PETP film.

The dry layer thickness is 10 um. After an exposure of 20 seconds development is carried out for 30 seconds in a water/methanol mixture (1:3). A very good opaque image is obtained.

Example 4 A mixture of 775 parts of styrene/maleic acid butyl semiester copolymer of a mean molar mass of 130,000, 436 parts of N,N-dimethylaminopropyl acrylamide, 161 parts of benzoin-sec.- butyl ether, 26 parts of the sodium salt of 2,#-dichloro-fluorescein and 56 parts of p-toluylmethyl hydroxysulphone are dissolved in 2445 parts of butanol and 5514 parts of methanol.

Layers are cast directly onto polyester film using a 0.25 #m doctor blade, and then dried. The dry layer thickness is 11 urn. It is image-wise exposed for 15 seconds using an BBO 200. The development is carried out over a period of not more than 30 seconds at room temperature using a mixture of water/methanol (1:10). A very good opaque image is obtained.

Example 5 A mixture of 775 parts of styrene/maleic acid butyl semiester copolymer of a mean molar mass of 150,000, 436 parts of N,N-dimethylaminopropyl acrylamide, 21 parts of Michler's ketone and 109 parts of benzophenone are dissolved in 2455 parts of butanol and 5514 parts of methanol. Layers are cast using a 0.25 mm doctor blade directly onto PETP film, and then dried. The dry layer thickness is 9 urn. It is imagewise exposed for 5 seconds using an HBO 200. The development is carried out over a period of not more 30 seconds at room temperature with methanol. A very good opaque image is obtained.

Example 6 A mixture of 775 parts of styrene/maleic acid butyl semiester copolymer of a mean molar mass of 310,000, 436 parts of ,N-dimethylaminopropyl acrylamide, 21 parts of Michler's ketone and 109 parts of benzophenone are dissolved in 2455 parts of butanol and 5514 parts of methanol. A layer is cast using a 0.25 mm doctor blade directly onto PETP film and then dried. The dry layer thickness is 9 urn. It is exposed for 2 seconds using an HBO 200. The development is carried out over a period of not more than 30 seconds at room temperature with methanol. A very good opaque image is obtained.

Example 7 A material corresponding of that of Example 1 is exposed using a bar screen and developed. Using an electron microscope a resolution power of 1 um is determined and a very good edge definition ascertained.

Example 8 A material corresponding of that of Example 1 is, after image-wise exposure, placed in a developer bath for 30 mins. The exposed, layer areas are not removed and remain smudge-proof.

Example 9 A mixture of 207 parts of an alternating styrene/maleic acid butyl semiester copolymer of a mean molar mass of 300,000, 221 parts of a methyl methacrylate/maleic acid anhydride copolymer originally containing 12 mole F of anhyride units and reacted, in each case in an amount of 50 mole %, based on anhydride units, with ammonia and n-butylamine to form the semiamide and semiimide respectively , 156 parts of N,Ndimethylaminopropyl acrylamide, 7 parts of Michler's ketone, 38 parts of benzophenone and 33 parts of diphenyliodonium chloride are dissolved in 2,300 parts of methanol and 560 parts of n-butanol. The solution is cast directly onto PETP film and then dried. The dry layer thickness is 12 um. It is image-wise exposed for 1 second with an HBO 500 (high-pressure mercury lamp) at a distance of 1 metre.Development is carried out over a period of not more than 30 seconds by spraying with water at room temperature. A very good opaque image is obtained. The relative scattered light intensity is 50% of the incident light.

Example 10 A mixture of 193 parts of an alternating styrene/maleic acid butyl semiester copolymer of a mean molar mass of 300,000, 118 parts of a non-alternating styrene/maleic acid butyl semiester copolymer with 32 mole % maleic acid butyl semiester units having a mean molar mass of 200,000, 156 parts of N,N-dimethylaminopropyl acrylamide, 7 parts of 4,4'-bis -P-diethylaminobenzophenone, 38 parts of benzophenone and 33 parts of diphenyliodonium chloride are dissolved in 1950 parts of methanol and 900 parts of n-butanol. The solution is cast directly onto PETP film and then dried. The dry layer thickness is 10 um. It is image-wise exposed for 2 seconds with an HBO 500 at a distance of 1 metre. The development is carried out over a period of not more than 45 seconds at room temperature in a water/methanol (1:1) bath. A very good opaque image is obtained.The relative scattered light intensity is 50 %.

Example 11 A mixture of 190 parts of an alternating propylene/maleic acid butyl semiester copolymer of a mean molar mass of 35,000, 126 parts of a nonalternating ethyl acrylate/maleic acid butyl semiamide copolymer, with originally 18 mole % anhydride units and a mean molar mass of 180,000, 193 parts of diethylamino-2-hydroxypropyl methacrylate, 15 parts of methylene bisacrylamide, 7 parts of Michler's ketone, 38 parts of benzophenone and 41 parts of Ermethoxy- benzenediazonium tetrafluoroborate is dissolved in 1800 parts of methanol and 520 parts of n-butanol. The solution is cast directly onto PETP film and then dried. It is image-wise exposed for 1 second with an HBO 500 at a distance of 1 metre. The development is carried out over a period of not more than 45 seconds at room temperature in a water/methanol (1:4) bath. At very good opaque image is obtained.The relative scattered light intensity is 52 %.

Example 12 A material corresponding to that of Example 1 is after development immersed for 2 minutes in a 2 % strength aqueous solution of Solamin light Turkish blue and then sprayed for 5 seconds with water. The optical density of the exposed parts of the layer in the absorption maximum of the dye is greater than 1.8.

The unexposed areas of the layer are fog-free.

Example 13 A material corresponding to that of Example 1 is after development immersed for 5 minutes in a 3% strength aqueous solution of Wofalan black and then sprayed with water for 5 seconds. The optical density of the exposed layer in the absorption maximum of the dye is 1.6. The unexposed parts of the layer are fogfree.

Example 14 A material corresponding to that of Example 1 is, after image-wise exposure, developed for 5 minutes at room temperature in a 2 % strength aqueous solution of Solamin light Turkish blue and then sprayed for 5 seconds with water. Strongly coloured images with an optical density of the exposed parts of the layer in the absorption maximum of the dye of greater than 2.0 are obtained. The resolution power is 140 lines/mm and the images have a very good edge definition.

Example 15 A mixture of 248 parts of an alternating styrene/maleic acid butyl semiester copolymer of a mean molar mass of 300,000, 88 parts of methylmethacrylate/maleic acid anhydride copolymer originally containing 12 mole % of anhydride units, and reacted in an amount of 50 mole % in each case, based on anhydride units, with ammonia and n-butylamine to form the semiamide and semiimide respectively , 156 parts of N,N-dimethylaminopropyl acrylamide, 7 parts of Michler's ketone, 38 parts of benzophenone and 33 parts of diphenyliodonium chloride are dissolved in 2,200 parts of methanol and 670 parts of n-butanol. The solution is cast onto an aluminium support which has been treated beforehand with phosphoric acid, and then dried. The dry layer thickness is 12 urn. Exposure is carried out for 10 seconds with a Tesla burner RVIF 3,500 at a distance of 80 cm. Development is carried out over a period of not more than 45 seconds by spraying with water at room temperature. The developed material is then immersed for 2 minutes in a 2 % strength aqueous solution of Solamin light Turkish blue and subsequently sprayed again for 5 seconds with water. Very easily visible images with a resolution power of 100 lines/mm are obtained.

Claims

Patent claims

1. Photopolymerisable material comprising a light sensitive layer that comprises a modified maleic anhydride copolymer having salt-forming groups and having an average molecular weight of from 20,000 to 500,000.

2. A photopolymerisable material as claimed in claim 1, wherein the light-sensitive layer comprises an ethylenically unsaturated monomer having at least one group capable of acting as a complementary salt-forming group with respect to the salt-forming groups of the copolymer.

3. A photopolymerisable material as claimed in claim 1 or claim 2, wherein the light-sensitive layer has a thickness of not more than 30um.

4. A photopolymerisable material as claimed in any one of claims 1 to 3, wherein the modified maleic anhydride copolymer is an alternating copolymer, and the light-sensitive layer further comprises a modified nonalternating maleic anhydride copolymer of average molecular weight of from 10,000 to 300,000 having saltforming groups and containing 60 to 95 mole % of a comonomer, the amount of the modified alternating maleic anhydride copolymer being 20 to 95% of the total maleic anhydride copolymer content of the layer.

5. A polymerisable material as claimed in claim 4, wherein the non-alternating maleic anhydride copolymer is present in an amount of from 5 to 80% of the total maleic anhydride copolymer content of the layer.

6. A photopolymerisable material as claimed in any one of claims 1 to 5, wherein the light-sensitive layer comprises a mixture of a modified alternating maleic anhydride/styrene copolymer and at least one modified non-alternating maleic anhydride/methyl methacrylate copolymer.

7. A photopolymerisable material as claimed in any one of claims 1 to 5, wherein the modified maleic anhydride copolymer or modified maleic anhydride copolymers coagulate and form polyelectrolyte complexes on development of the material after exposure.

8. A photopolymerisable material as claimed in any one of claims 1 to 7, wherein the light-sensitive layer is applied to a support.

9. A photopolymerisable material substantially as described in any one of Examples 1 to 15 herein.

10. A method for the manufacture of a polymerisable material as claimed in any one of claims 1 to 9, wherein the light-sensitive layer is prepared by applying a solution of dispersion of the copolymer to the support.

11. An image-bearing material that has been obtained by the image-wise exposure to actinic radiation of a photopolymerisable material as claimed in any one of claims 1 to 9, followed by development.

11. Any novel feature or novel combination of features described herein.

Amended claims 1. Photopolymerisable material comprising a light sensitive layer that comprises a modified maleic anhydride copolymer having salt-forming groups and having an average molecular weight of from 20,000 to 500,000.

6. A photopolymerisable material as claimed in any one of claims 1 to 5, wherein the light-sensitive layer comprises a mixture of a modified alternating maleic anhydri#de/styrene copolymer and at least one modified non-alternating maleic anhydride/methyl methacrylate copolymer.

10. A method for the manufacture of a polymerisable material as claimed in any one of claims 1 to 9, wherein the light-sensitive layer is prepared by applying a solution or dispersion of the copolymer to the support.

12. Any novel feature or novel combination of features described herein.

13. A photopolymerisable material comprising a support and at least one light-sensitive layer, the layer comprising a modified maleic anhydride copolymer of average molecular weight of from 20,000 to 500,000 having salt forming groups and an ethylenically unsaturated monomer having at least one group capable of acting, as a complementary salt-forming group with respect to the salt-forming groups of the copolymer, in which material, on development of the layer following exposure, coagulation will occur and polyelectrolyte complexes will be formed.

14. A photopolymerisable material comprising a support and at least one light-sensitive layer, the layer comprising a modified alternating maleic anhydride copolymer of average molecular weight of from 20,000 to 500,000 having salt-forming groups, a modified nonalternating maleic anhydride copolymer of average molecular weight of from 10,000 to 300,000 having saltforming groups and containing from 60 to 95 mol % of comonomer - derived units and an ethylenically unsaturated addition-polymerisable monomer having at least one primary, secondary or tertiary amino group, the amount of the modified alternating maleic anhydride copolymer being from 20 to 95% of the total maleic anhydride copolymer content of the layer, whereby, on development of the layer following exposure, coagulation will occur and polyelectrolyte complexes will be formed.

15. A photopolymerisable material as claimed in claim 13 or claim 14, wherein the light-sensitive layer comprises a radical-forming initiator system.

16. A photopolymerisable material as claimed in claim 13 or claim 14, wherein the thickness of the lightsensitive layer is not more than 30 um.