DE3641014A1 - PHOTOPOLYMERIZABLE MATERIAL - Google Patents

Description

The invention relates to a photopolymerizable material, that for information recording, especially as reproductive material, for the production of printed circuits and relief images for printing plates or for the production of image-hardened coatings is suitable.

It is known that a variety of ethylenically unsaturated Compounds can be polymerized in that a Photo initiator forms radicals under the influence of light and these radicals initiate polymerization. They are one Series of compounds known to be under the influence of light various mechanisms form radical radicals, which then form the Can trigger photopolymerization (see H. Baumann, H. J. Timpe, H. Böttcher, Z. Chem. 23 (1983) 197).

With the help of these photoinitiators, photopolymerizable Build up layers that are polymerizable in addition to the photoinitiator or crosslinkable compounds and a binder contain.

Since the polymeric binders, like other hydrocarbons, are oxidatively degraded by atmospheric oxygen during storage and for many vinyl polymers and olefins, the total activation energy of the gross polymerization rate without initiation step is only 20 kJ mol ^-1 (J. Ulbricht, basis for the synthesis of polymers Akademie-Verlag Berlin , 1978), inhibitors are expediently added to the photopolymerizable layers. These inhibitors increase the storage stability of the photopolymerizable layers and thus prevent thermal fogging.

In the patent literature, the following classes of substances are described as inhibitors, among others: phenols, e.g. B. p-methoxyphenol, t-butyl catechol, β- naphthol, hydroquinone, quinones, e.g. B. p-benzoquinone, 2,5-diphenyl-p-benzoquinone; organic nitrogen compounds, e.g. B. Amines (US-PS 41 67 415, 40 57 431, GB-PS 15 53 823, DE-OS 25 17 034, US-PS 40 53 317), N-nitroso compounds (DE-AS 12 91 620, US- PS 40 55 317, 36 15 629), thiourea, thiosemicarbazide, thiosemicarbazone (DE-OS 30 13 170); organic phosphorus compounds, e.g. B. Phosphines (US-PS 39 32 188, 40 97 283) phosphites (DE-OS 19 34 637, 21 04 958, DE-AS 10 98 712, US-PS 41 16 788); Epoxides, e.g. B. 1.2.Epoxydekan, glycidyl acrylate, styrene oxide (US-PS 41 46 453) and organosulfur compounds (US-PS 41 68 981, DE-OS 12 82 447). The inhibitors are generally used in a concentration of 0.001 to 10%, based on the compound to be polymerized.

In addition to the initiators, inhibitors, monomers and binders If necessary, the photopolymerizable layers or several additives such as plasticizers, pigments or dyes contain. Furthermore, oxygen extinguishers, e.g. B. bis-tetrahydrofuran carboxamide (DE-AS 22 45 549) photopolymerizable layers added to the inhibiting To suppress the influence of oxygen.

The photopolymerizable layer is then applied a solution or dispersion of all individual components on the Pad applied. The most varied are suitable as a base natural or synthetic materials used as flexible or rigid film or plates can be produced can.

The photopolymerizable layers are used for image generation hardened on exposure. The pictorial hardening generally does not lead to visual images but to a pictorial change in physical properties the exposed areas due to polymerization or crosslinking. These property changes can then be done in a downstream Development step can be used for visualization (see H. Böttcher, J. Signal AM, 8 (1980) 405). After development you get relief images on the substrate, the can be used as a printing form or after staining result in a review or supervision picture.

The aim of the invention is to develop photopolymerizable Materials with improved detail reproduction and  improved thermal storage stability.

The invention has for its object such organic To find compounds for photopolymerizable materials, suppress the reflected light effects and stray light effects and prevent thermal fogging without the Sensitivity (reactivity) of the material adversely influence.

According to the invention the object is achieved in that a photopolymerizable material, consisting of a base, at least one photosensitive layer that consists of Monomer, initiator, binder, inhibitor and other additives composed, as well as, if necessary, further auxiliary layers, Compounds with N-oxyl structural units corresponding to the Formula I, which fixes freely and / or via Coulomb interactions and / or fixed covalently, as polymer chain segments or Substituents of a polymer are present.

wherein

R¹-R⁴ = identical or different H, alkyl,

contains.

The photopolymerizable layers are preferably steric hindered cyclic 5- or 6-ring N-oxyls of the formula II, with R¹-R⁴ = C₁-C₄ alkyl added.

Advantageously, 6-ring N-oxyls are used according to formula III freely and / or via Coulomb interactions fixed, present in the layer and / or accordingly of the formula IV with 1-50 mol% constituent of a Co, Ter or Multipolymers are, which itself is the layer binder represents or is added to the binder.

As substituents are preferably for R¹-R⁴ = CH₃; X = NR⁶-, -O-; R⁵ = C₁-C₁₈ acid residue z. B. acetyl, benzoyl, salicyl, 2-ethylhexanoyl; R⁶ = H, CH₃; Y = carboxy group of a modified maleic acid unit which forms a co-, ter- or multipolymer with styrene, methyl methacrylate-modified maleic acid units, vinyl acetate, vinyl ether, α- methylstyrene, propylene and other α- olefins.

R¹-R⁴ = identical or different H, alkyl; R⁵ = H, alkyl, Aryl; C₁-C₁₈ acid residue R⁶ = H, CH₃

n = 0.1.

However, polymeric N-oxyls can also be used in addition to polymer-bound N-oxyl substituents, polymer-bound Contain piperidine residues.

The N-oxyl concentration in the layer is between 10 and 10⁴ ppm, based on the monomer, depending on the monomer used. The photopolymerizable layers furthermore contain organic compounds which have one or more radically polymerizable groups (monomer). Furthermore, the photopolymerizable layers contain a natural or synthetic binder. The addition of binder is particularly expedient when the compounds to be polymerized are liquid substances. Suitable binders are those polymers or polymer mixtures which, after exposure, have a sufficiently high solubility to the developer. Suitable polymers include gelatin, polyvinyl alcohol, polyvinyl pyrrolidone, copolymers of maleic anhydride with styrene, α- methylstyrene, propylene, methyl methacrylate. The use of binders with carboxyl groups increases the diffusion resistance of the N-oxyls used.

To initiate the photopolymerization, the photopolymerizable Layers of initiators added under Influence of light according to various mechanisms radicals form, which then trigger a polymerization or crosslinking. The photopolymerizable layers are still characterized in that, depending on the intended use, Plasticizers, pigments or dyes are added can.

The photopolymerizable layers are best through Application of a solution or dispersion of all individual components applied to the pad. Are suitable as a base various natural or synthetic materials, which are produced as flexible or rigid foils or plates can be such. B. copper, oriented polyester film, laminated papers, glass, sandblasted with aluminum oxide Aluminum, silicon and wood.

The photopolymerizable materials are used for image generation networked during exposure, d. H. hardened figuratively. The The layers produced according to the invention are exposed with the high pressure mercury lamps commonly used in repro technology, High pressure xenon lamps or halogen spotlights. But sunlight is also suitable for the exposure. After the imagewise exposure, development takes place with a solvent tailored to the overall system or -mixture. Which development time is necessary depends on according to the layer thickness, the binder used and the Temperature. However, the development time is general <10 minutes.

example 1

A mixture consisting of 60 parts of styrene-butyl half-ester copolymer, 50 parts of pentaerythritol tetraacrylate, 2 parts Michler's ketone, 10 parts benzophenone, 10 parts diphenyl iodonium chloride, 0.02 parts of N-oxyl of the formula III with R¹-R⁴ = CH₃; R⁵ = CH₃CO-; X = -NH-, 200 parts of butanol and 620 parts of methanol, is with the help Pour a 0.25 nm doctor blade onto PETP film and at room temperature dried.

The mask is exposed for 10 s using a high-pressure mercury lamp, HBO 500, at a distance of 80 cm.

After development with a 2% aqueous Na₂CO₃ solution you get a relief image that z. B. with Solamin light turquoise blue can be stained.

Example 2

A mixture consisting of 77 parts of styrene-butyl half-ester copolymer, 43 parts of N, N-dimethylaminopropylacrylamide, 2 parts Michler's ketone, 10 parts bezophenone, 10 parts Diphenyliodonium chloride, 0.015 parts of the N-oxyls Formula II with R¹-R⁴ = CH₃; R⁵ = CH₃CO-; X = -NH-, 600 parts of methanol and 250 parts of butanol, is with the help a 0.1 mm squeegee onto one blasted with alumina Aluminum plate applied.

The dry layer thickness is after room temperature drying 8 µm.  

The material is imagewise exposed for 15 s an HBO 500 at a distance of 80 cm. After development with water you get a relief image that z. B. with Walkbrillan red can be stained.

Example 3

A mixture consisting of 60 parts of styrene maleic acid propyl half ester copolymer, 40 parts of pentaerythritol tetraarylate 10 Parts methylene bisacrylamide, 2 parts Michler's ketone, 10 Parts benzophenone, 10 parts diphenyl iodonium chloride, 0.02 Share the N-oxyl of formula III with R¹-R⁴ = CH₃; R₅ = PhCO X = -O-, 600 parts of methanol and 250 parts of propanol is applied using a 0.25 mm doctor blade Cellite foil applied and dried at room temperature. The imagewise exposure takes place for 10 s with an HBO 500 in a distance of 80 cm.

After development with a 1% KOH solution, one obtains a relief image that z. B. stained with Wofalan black can.

Example 4

A mixture consisting of 76 parts of a styrene-butyl half-ester copolymer, 40 parts of N, N-dimethylaminopropylacrylamide, 10 parts of triethanolamine trisacrylate, 2 parts Michler's ketone, 10 parts benzophenone, 10 parts diphenyl iodonium chloride, 1 part of a polymeric N-oxyl of the formula IV, which consists of 50 mol% styrene, 48 mol% maleic acid butyl half ester and 2 mol% maleic acid 4- (2,2,6,6-tetramethylpiperidino- N-oxyl) half amide, 250 parts butanol and 600 parts of methanol is unsubstrated with a 0.25 mm doctor blade Pour PETP film and then at room temperature dried.

The imagewise exposure takes place for 10 s with an HBO 500 in a distance of 80 cm. Obtained after development with water one a relief picture, which z. B. with Solamin light turquoise blue can be stained.

Example 5

A mixture consisting of 50 parts of gelatin, 25 parts of polyvinyl alcohol, 2 parts m, m′-disulfonated Michler's ketone, 10 parts of the sodium salt of p, p'-benzophenenedisulfonic acid, 10 parts diphenyl iodonium hydrogen sulfate, 40 parts acrylamide, 40 parts of N, N-dimethylaminopropylacrylamide, 20 parts of methylene bisacrylamide, 0.04 part of the N-oxyl of formula III  with R¹-R⁴ = CH₃; R⁵ = CH₃CO; X = -NH-, 1200 parts of water and 300 parts of methanol, using a 0.1 mm doctor blade on an aluminum plate blasted with aluminum oxide applied and dried at room temperature.

The imagewise exposure takes place for 15 s with an HBO 500 in a distance of 80 cm. After development is with water a relief image recognizable, the z. B. stained with methylene blue can be.

Example 6

A mixture consisting of 50 parts of polyvinylpyrrolidone, 10 Parts 2-methylstyrene maleic acid butyl half ester, 30 parts Pentaerythritol tetraacrylate, 10 parts trisacrylic formal, 10 parts Glycerol trisacrylate, 2 parts Michler's ketone, 10 parts Benzophenone, 10 parts diphenyl iodonium chloride, 0.01 parts of N-oxyls of the formula III with R¹-R⁴ = CH₃; R⁵ = CH₃CO-; X = -O-, 250 parts of ethanol and 600 parts of methanol, with Pour with the help of a 0.25 mm doctor blade and then with Room temperature dried.

The imagewise exposure takes place for 10 s with an HBO 500 in a distance of 80 cm. The development was done with methanol and resulted in a relief image that z. B. dyeable with methylene blue is.

Example 7-12

The unexposed material samples from Example 1-6 are after drying at room temperature for 2.5 hours at 50 ° C stored. The samples treated in this way are analogous to the examples 1-6 exposed, developed and stained. You get completely fog-free relief images that correspond to detail reproduction the materials of Examples 1-6.

Example 13-18

To check the thermal storage stability, each 100 ul of the mixtures from Examples 1-6 to 1 cm₂ large nickel plate applied and then dried. With these samples, the reactivity becomes photocalorimetric of the corresponding material determined and standardized to 1. Further sample platelets with mixtures of Examples 1-6 are stored after drying for 2.5 hours at 50 ° C and then examined photocalorimetrically. Table 1 once again illustrates the very good thermal storage stability of the materials examined.  

Example 19-24 (Comparative Examples Without N-Oxyl)

Mixtures of Examples 1-6, but without the addition of the corresponding ones N-oxyls are analogous to Examples 1-6 applied to the appropriate documents, dried and then stored at 50 ° C for 2.5 hours. The so treated materials are according to the examples 1-6 exposed and developed. You get completely veiled Relief pictures without detail reproduction, which are not for Information recording are suitable.

Example 25-30 (comparative example without N-oxyl)

100 µl of the mixtures of Examples 19-24 are added to each applied a 1 cm² nickel plate, dried, Stored at 50 ° C for 2.5 hours and then photocalorimetric examined. After heat treatment decreases the reactivity of the samples by 90% (see Tab. 1).

Table 1

Relative reactivity of the photopolymerizable mixtures before and after storage for two and a half hours at 50 ° C

Example 31 (prior art)

A mixture consisting of 60 parts of styrene-butyl half-ester copolymers, 50 parts of pentaerythritol tetraacrylate, 2 Parts Michler's ketone, 10 parts benzophenone, 10 parts  Diphenyl iodonium chloride, 0.2 part hydroquinone monomethyl ether, 200 parts of butanol, 620 parts of methanol is made using a Pour 0.25 mm doctor blade onto PETP film and at room temperature dried.

The material is then exposed for 30 s an HBO 500 at a distance of 80 cm. After development with water you get a relief image that z. B. with Solamin light turquoise blue can be colored.

The unexposed material is stored at 50 ° C for 2.5 hours and then under the above Exposed conditions, then you get after development with water a heavily veiled Relief image that shows insufficient color density differences after staining between exposed and unexposed areas of the image having.

Claims (4)

1. Photopolymerizable material, consisting of a base, at least one light-sensitive layer, which is composed of monomer, initiator, binder, inhibitor and other additives, and optionally further auxiliary layers, characterized in that it contains compounds with N-oxyl structural units, according to formula I. which are free and / or fixed via Coulomb interactions and / or covalently fixed, as polymer chain segments or substituents of a polymer, are present in the layer whereinR¹-R⁴ = identical or different H, alkyl contains. 2. Photopolymerizable material according to claim 1, characterized in that it is sterically hindered cyclic 5- or 6-ring N-oxyls of the formula II whereinR¹-R⁴ = identical or different mean C₁-C₄ alkyl, contains. 3. Photopolymerizable material according to claim 1 and 2, characterized in that there are 6-ring N-oxyls which are free according to the formula III and / or fixed via Coulomb interactions in the layer and / or according to the formula IV with 1-50 mol% are part of a co-, ter- or multi-polymer, whereinR¹-R³ = identical or different C₁-C₄-alkyl R⁵ = H, alkyl, aryl, acyl, C₁-C₁₈ acid residue R⁶ = H, CH₃ n = 0.1, contains. 4. Photopolymerizable material according to claims 1-3 in that it contains the N-oxyl structural units in a concentration between 10 and 10⁴ ppm, based on monomer.