DD236739A1 - PHOTOPOLYMERIZABLE COMPOSITION - Google Patents

Abstract

The invention relates to a photopolymerizable composition for the production of printing plates, relief images and for information recording. The aim of the invention is to improve the photosensitivity of the photopolymerizable composition in the visible spectral range. The task of developing initiators with a higher efficiency of radical formation is achieved by using the photopolymerizable composition as initiator system an organic peroxide, an acid, a pyrylium cation of general formula I and an α-hydroxycarboxylate of general formula II, where R 1 to R 5 are identical or different radicals such as hydrogen, optionally substituted phenyl rings or electron-withdrawing substituents and R6 and R7 are identical or different radicals such as hydrogen, alkyl and / or optionally substituted phenyl groups, contains. Formulas I, II

Description

and an α-hydroxycarboxylate of the general formula

where Ri to R _{5 are} identical or different radicals such as hydrogen, optionally substituted phenyl rings or electron-withdrawing substituents and R ₆ and R _{7 are} identical or different radicals such as hydrogen, alkyl and / or optionally substituted phenyl groups.

Field of application of the invention

The invention relates to a photopolymerizable composition which can be used for the production of printing plates, relief images and for information recording.

Characteristic of the known technical solutions

It is known that ethylenically unsaturated compounds can be brought to polymerization in the presence of a photoinitiator by light. If such systems are present in thin layers, the properties altered by the polymerization, such as adhesion, solubility, swellability or stickiness, can be used to record information (J.Verebst, Chimia 34/1980 /, 190-199). An important influence on the photosensitivity has the photoinitiator. In most cases, the initiator decomposes into radicals when exposed to light, causing polymerization. Examples of photoinitiators are dye-redox systems (US Pat. No. 3,092,096), benzoin ethers (DE-OS 2232365), hexaaryibisimidazoles in a mixture with amino compounds (DE-OS 3211312), furthermore benzophenone and its derivatives such as Michler's ketone, xanthen-9-one, thioxanthen-9-one , Anthraquinone derivatives, etc. (see also Böttcher, Epperlein, Modern Photographic Systems, VEB Deutscher Verlag für Grundstoffindustrie, Leipzig 1983). Photopolymerizable compositions with these initiators often have the disadvantage that their effectiveness is too low. Often you try this deficiency by adding thermal initiators such. B. to eliminate organic peroxides (DE-OS 2919416). Another disadvantage of many photopolymerizable compositions is their insensitivity to visible light. In DE-OS 3332286 sensitive in the visible spectral range initiator combination consisting of pyrylium, thia or Selenapryryliumsalzen and organic peroxides is described. In this system, it is disadvantageous that, especially when using the anions perchiorate and tetrafluoroborate, which are designated as preferred, the absorbed light is not completely utilized for the formation of radicals, but is lost to a considerable extent by fluorescence. This does not achieve the potentially high sensitivity of this system.

Object of the invention

The aim of the invention is a photopolymerizable composition with improved sensitivity in the visible spectral range.

Explanation of the essence of the invention

The object of the invention is to develop a photoinitiator system which forms radicals on exposure of the photopolymerizable composition with higher efficiency. The object is achieved in that the photopolymerizable composition as an initiator system

an organic peroxide,

an acid,

a Pyryliumkation of the general formula

-2- 758

and an α-hydroxycarboxylate of the general formula

^ C CC ©

where Ri to R _{6 are} identical or different radicals such as hydrogen, optionally substituted phenyl groups or electron-withdrawing substituents and R ₆ and R _{7 are} identical or different radicals such as hydrogen, alkyl and / or optionally substituted phenyl groups.

Suitable organic peroxides are compounds with 0-O bonds, for. As dibenzoyl peroxide, di-tert-butyl peroxide, lauroyl peroxide, etc. As the acid may preferably be used to the a-hydroxycarboxylate belonging carboxylic acid, optionally in combination with other acids, for. B. sulfonic acids. As electron-withdrawing substituents carbonyl, carboxyl, carbamoyl, ester, cyano and nitro groups are suitable. As α-hydroxycarboxylates, in addition to glycolic acid salts, ring-substituted benzilates or almonds, if appropriate, are preferably used.

The photopolymerizable composition of the invention may contain as ethylenically unsaturated compounds all known mono-, oligo- and polymers, for. As acrylic and methacrylic acid monohydric or polyhydric alcohols such as methyl methacrylate, ethylene glycol diacrylate, trimethylolpropane triacrylate, but also acrylamide derivatives, butadiene polymers or unsaturated polyesters. It is advantageous to use a binder for property improvement.

Suitable binders are z. As polyacrylate, polymethacrylate, polyvinylpyrrolidone, polyvinyl acetate, polyvinyl acetates, cellulose derivatives and polyurethanes. Pigments or dyes may be added to the binder for contrasting purposes. To improve the storage stability, preferably 0.01 to 0.1% of an inhibitor is added, for. As hydroquinone or p-methoxyphenol.

The photopolymerizable composition is preferably used in the following concentration ratios (% by weight):

Pyrylium cation (e.g., as Cl ", CIOJ, etc.) 1-10

organic peroxide 2-30

Carboxylates. As tetraalkylammonium salt) 1-20

Acid 0.1-10

ethylenically unsaturated compound 10-50

Binder 0-80

Inhibitor 0.01-0.1

If necessary, the exposed composition can be made insensitive to daylight with NH3 gas.

Thus, the composition between exposure and further processing in the daylight is storable.

The photopolymerizable composition of the present invention is characterized by high sensitivity of blue and green light.

Exemplary embodiments Example 1

A 0.1 mm thick polyester film is coated with the following gassing solution:

100 ml acetone / methylene chloride (2: 1)

10 g of polyvinyl acetate

3 g of pentaerythritol triacrylate

2 g Triemthyllolpropantrimethacrylat

0.3 g of 2,6-diphenyl-4-carboxylpyrylium perchlorate

0.5 g of dibenzoyl peroxide

0.5 g of tetraethylammonium anisilate

0.2 g of anisilic acid

0.07 g of p-toluenesulfonic acid

0.02 g of p-methoxyphenol

The layer is dried at room temperature for 24 hours with exclusion of light. The exposure was carried out with a 200 W high pressure mercury lamp (366, 405 and 436 nm) monochromatically and with an argon ion laser (488 and 514 nm) each through a mask. The irradiation time was chosen so that after development (methanol / acetone 2: 1) a sharp, abrasion-resistant relief image was formed.

As a comparative example, layers were prepared whose composition corresponds to the above information but which contained neither anisilate nor acid (the composition of the comparative layers thus corresponds to DE-OS 3332286). Here, the irradiation time required for an image comparable to the above relief image is larger by a factor of 2 to 3.

Claims (1)

-1- 758 61 Invention claim: 1. A photopolymerizable composition consisting of at least eienr ethylenically unsaturated compound, a photoinitiator and optionally a binder and further additives, characterized in that the photopolymerizable composition as an initiator system
an organic peroxide,
an acid,
a Pyryliumkation of the general formula