DD243573A1 - NEGATIVELY WORKING PHOTOPOLYMERIZABLE COMPOSITION - Google Patents

Abstract

The invention relates to an alkaline developable photopolymerizable composition for the production of relief images for information recording materials, negative printing plates and printed circuits. The composition according to the invention contains a radical-forming photoinitiator, at least one ethylenically unsaturated compound and a binder mixture of an alkali-soluble polymer and an oligomer of the structure (see formula). The new composition improves the physical-mechanical properties of wet-crosslinked areas.

Description

-η

wherein

η = 3-10, R ₁ = H, CH ₃ , C ₂ H ₅ , C ₆ H ₅ , contains.

Field of application of the invention

The invention relates to a negative-working photopolymerizable composition for the production of relief images for information recording materials, negative printing plates and printed circuits.

Characteristic of the known technical solutions

Photopolymerizable compositions are currently very versatile. Examples of these are photoresists, light-crosslinkable lacquer layers for the insulation or refinement of surfaces, printing plates, printing inks, printed circuits, information recording materials or dental prostheses. They comprise as main components at least one ethylenically unsaturated compound which, in the presence of photoinitiators, is converted by irradiation into higher molecular weight, mostly crosslinked compounds, thereby achieving a change in adhesion, tackiness, refractive index or solubility. Examples of free-radically polymerizable unsaturated compounds are preferably polyfunctional acrylic or methacrylic acid esters, such as butanediol diacrylate, ethylene glycol diacrylate, trimethylolpropane triacrylate or pentaerythritol tetraacrylate (US Pat. No. 2,760,863, 2,791,504, 3,066,112, 3,353,955).

As further components photopolymerizable compositions usually contain a binder, stabilizers and contrast agents such as dyes or pigments. The binder used not only determines the nature of the development of photosensitive photopolymerizable layers, but also significantly the physico-mechanical properties. As organically developable binders are described polybutadiene (US Patent 3,024,180), polyurethanes (US Patent 2948611), chlorinated polyolefins (DE-PS 2414240), diene block copolymers (EP-PS 27612) or polyvinyl polymers (DE-PS 2759164). More advantageous is the use of binders that enable an environmentally friendly aqueous development. Examples are polyvinyl alcohol (GB-PS 834337), polyacrylamide (CH-PS 594704), acrylic acid or methacrylic acid. Mixed polymers (DE-PS 2320849), styrene-maleic acid half-ester copolymers (DE-PS 2205146) or carboxyl-containing oligomers based on α-methylstyrene (DD-PS 155361). The use of polyvinyl alcohol and polyacrylamide is possible only in those compositions containing water-soluble ethylenically unsaturated compounds and initiators and thus very limited. However, the known alkali-soluble binders are also associated with a number of disadvantages. Thus, these are mostly included in the light-crosslinked areas.

This causes a high water absorption and swelling of the irradiated areas and thus easy vulnerability of the relief structures in the developing baths. When mechanical treatment is used to promote development in the aqueous baths, damaged or blurred relief images are often obtained.

Object of the invention

The aim of the invention is a negative-working photopolymerizable composition which is aqueous-alkaline developable and allows the production of layers and relief images with improved physical and mechanical properties in the wet state.

-2- 243 573 Explanation of the essence of the invention

It is an object of the invention to develop a new binder system, which is firmly anchored in the crosslinked areas and improves the strength of the layers or relief images in the wet state and thus ensures low vulnerability in the development baths under mechanical stress.

This object is achieved according to the invention in that the aqueous alkaline developable photopolymerizable composition consisting of at least one photosensitive, radical-forming initiator and an ethylenically unsaturated compound, a binder mixture of an alkali-soluble polymer and an oligomer of the structural formula

CH.,

⁰ 0

UUUC-GiI = CH-CO-Cl-I-CW ₀ -OC-CM ₀ -O-CU-CU-OC-Gi-I-CiI-CUUn

2 2 2 |

wherein π = 3-10, R ₁ = H, CH ₃ , C ₂ H ₅ , C ₆ H ₅ mean.

The ratio of alkali-soluble polymers to oligomers is 20: 1 to 1: 9, preferably 1: 1 to 4: 1. Suitable alkali-soluble binders are all known acid-containing copolymers, for example copolymers based on styrene-maleic acid half-esters, acrylic acid esters, methacrylic acid-methacrylic acid esters, acrylic acid-styrene acrylic esters, cellulose succinates or carboxyl-containing oligomers based on α-methylstyrene according to DD-PS 155361 As radical-forming photoinitiators, the photopolymerizable composition may comprise all known photosensitive compounds or mixtures thereof, as described, for example, in Chem. Rev. 68 (1968) p. 125 and Z. Chem. 23 (1983).

P. 197. Acrylic acid esters, epoxy acrylates (US Pat. No. 3,066,112) and urethane acrylates (US Pat. No. 4,131,723) are particularly suitable as ethylenically unsaturated compounds. However, it is also possible to include other known ethylenically unsaturated compounds, for example unsaturated polyesters (US Pat. No. 3,794,494) and prepolymers based on butadiene (German Pat. No. 293,989).

To improve the storage stability, it is advantageous to add to the composition stabilizers which suppress thermal polymerization. Depending on the application of the composition according to the invention, the visualization (contrasting) of the relief images may furthermore contain dyes or pigments such as carbon black.

For optimum sensitivity, it is necessary to provide the photosensitive layers in a known manner with a protective layer of polyvinyl alcohol, gelatin, polyvinylpyrrolidone or other known oxygen-impermeable polymers.

The composition of the invention preferably contains

50-70% by weight of binder

10-60% by weight of ethylenically unsaturated compounds

3-20% by weight initiator

0.01-0.5% by weight of stabilizer

1-10% by weight of pigments

Suitable solvents are alcohols, esters, ketones or chlorinated hydrocarbons.

The composition according to the invention is suitable for the production of information recording materials, negative printing plates, coatings or printed circuits.

It is characterized by a good solubility in the known solvents and allows a complete removal in the known aqueous alkaline development baths. The binder mixture according to the invention is well compatible with the conventional ethylenically unsaturated compounds and gives tack-free layers with improved physico-mechanical properties in the wet state.

embodiments example 1

On a 100 / thick polyethylene terephthalate base, the following compositions are coated and dried at 50 ° C:

ml composition B C connection ml A 40 40 acetone G 40 10 10 ethyl glycol G 10 0.48 0.48 benzoin G 0.48 1.2 1.2 Trimethylölpropantriacrylat G 1.2 2.89 - Binder 1 G 3.46 - 2.9 Binder 2 - 0.8 1.0 Binder 3 -

Binder 1: copolymer of the composition styrene / ethyl acrylate / acrylic acid = 50/32/18 (wt .-%) with a

average molecular weight of 76000. Binder 2: alternating copolymer of styrene and maleic acid half-ester having an average molecular weight

of 95000 binder 3: oligomer of the structure

!! UOC-CM = C; ! -GO-CIi ₂ -CH ₂ -

CiL i °

^A - i '- - - n_ с ! - '' * '! -O-C-C''= Ci I-

Subsequently, the dried layers are provided with a protective layer of 2% polyvinyl alcohol solution. With a 500 W high-pressure mercury lamp, the plates are then exposed at a distance of 25 cm for 1 min. To determine the wet strength, the plates are swollen in a 0.1 η sodium hydroxide solution for 1 min. A steel mandrel is then moved over this moist layer, which is loaded with different weights. The layer of composition A shows a slight vulnerability at a load of 0.7 kp, while the layers of composition B and C are only broken at a load of 2.0 kp.

Example 2

On a ΙΟΟμ, ιτ »strong polyethylene terephthalate base, the following compositions are coated:

ml composition B connection ml A 750 acetone G 750 250 methyl ethyl ketone G 250 3 trimethylolpropane G 3 7 ethylene glycol G 7 0.08 2,6-di-tert-butyl-cresol ml 0.08 2.5 benzoin G 2.5 100 Carbon black dispersion (2% in butanol) G 100 - Binder 1 G 35 20 Binder 2 - 15 Binder 3 -

According to Example 1, these are provided with a protective layer of polyvinyl alcohol and 15s exposed with a 250 watt high pressure mercury lamp in the contact process under a photographic raster wedge with a density increase of V2. The development of the material takes place at 25 ° C 90s in a developer solution of:

950 ml of water 50 ml of isopropanol Ig NaOH 1 g of sodium sulfosuccinic acid dialkyl ester

The sample is then rinsed under a powerful jet of water. As a measure of the sensitivity of the composition, the number of recognizable levels is used. The following results are obtained:

Number of levels of halftone dot sharpness

8 deficient

9 good

With less sensitivity, poor halftone dot sharpness is obtained with Sample A by the water jet purging.

Example 3

Photosensitive layers of the following composition are prepared, exposed and developed analogously to Example 2:

connection ml A B C acetone ml 600 700 200 butanol ml 300 200 800 ethyl glycol G 100 100 - trimethylolpropane 9 4 - - Diethylenglykoldimetacrylat G 8th - - pentaerythritol G - - 15 butanediol G - 12 - Michler's ketone G 1 1 1 benzophenone G 7 7 7 2,6-di-tert-buthylkresol ml 0.05 0.5 0.5 Carbon black dispersion (2% in butanol) G 100 100 100 Binder 1 G 10 - 5 binder G 20 25 - binder G 8th 13 12 Binder 5 - - 20

Binder 4: Oligomer of the structure

i! OOC-CH = CH? CO-Cii-CH ₂ -Ü

CiL

CrL

Ci! ..,

-4

Binder 5: oligomer based on α-methylstyrene with carboxyl end groups corresponding to DD-PS 155361 The following results are obtained:

Composition A B

Number of steps 11

Halftone dot sharpness very good

12 very good

11 very good

The following compositions are applied to a pretreated aluminum substrate, as used in a known manner for negative printing plates:

connection ml A B C acetone ml 100 100 100 butanol G 900 900 900 pentaerythritol G 12 12 6 butanediol G - - 6 Michler's ketone G 1 1 1 benzophenone G 7th 7 7 2,6-di-tert-butyl cresol G 0.05 0.05 0.05 methylene blue G 0.1 0.1 0.1 binder G - 25 28 Binder 3 G - 9 8th Binder 6 36 2 -

Binder 6: copolymer of the composition methyl methacrylate / ethyl acrylate / aryl acid = 40/40/20 with a

average molecular weight of 65,000.

There is obtained a 20 ^ m thick layer, which is provided with a 1 μπτι strong protective layer of polyvinyl alcohol. After 2 min exposure with a 2000 watt high pressure mercury lamp through a template at a distance of 1 m is carried out at 25 ⁰ C for 1 min development in a 1% sodium carbonate solution. Subsequently, the plates are briefly treated with a water jet with a soft brush to completely remove the unexposed areas and dried. Relief images are obtained which absorb hydrophobic colors very well and show no quality fluctuations after 20,000 printing tests. The printing plate with the composition A is defective. In the mechanical treatment in the wet state, crosslinked areas of the layer are also removed or injured.

Claims (2)

Invention claim: A negative-working photopolymerizable composition which is aqueous-alkaline developable and at least one light-sensitive, radical-forming initiator, an ethylenically unsaturated compound and a binder, characterized in that it comprises as a binder a mixture of an alkali-soluble polymer and an oligomer of the structural formula о? ^H 3 Il HOOC-CH-CH-CO-CH-CH ₀ O C-CH -0-CH - CH-0-C-CH = CH-COOH , 2, 2 2