Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Patent
1986-12-03
1989-08-29
Reamer, James H.
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
568331, 562 41, 562 42, 564353, 564354, 564323, 564324, 560250, 560251, 560252, 560254, 522 40, 522 39, 522 46, C07C 4982
Patent
active
048619167
DESCRIPTION:
BRIEF SUMMARY
The invention relates to new ketone derivatives and their use as photoinitiators for the photopolymerization of ethylenically unsaturated compounds or systems containing these.
The invention relates in particular to the use of these compounds as photoinitiators for the photopolymerization of ethylenically unsaturated compounds in aqueous systems and to aqueous photopolymerizable systems containing such ketone derivatives. The invention also relates to photopolymerization processes for the preparation of aqueous polymer solutions or polymer dispersions and for the preparation of water-soluble or hydrophilic polymers, in which processes ketones of this type are employed as photoinitiators. The invention furthermore relates to the use of these compounds as photoinitiators generally, that is to say also in non-aqueous systems, and corresponding photopolymerizable systems.
Photochemically induced polymerization reactions have acquired considerable importance in industry, particularly when the rapid curing of thin layers is involved, such as, for example, in the curing of lacquer and resin coatings on paper, metal and plastics or in the drying of printing inks, since these processes are distinguished, compared with conventional methods for printing and coating articles, by a saving in raw materials and energy and by reduced pollution of the environment.
The preparation of polymer materials in themselves by the polymerization of corresponding unsaturated monomeric starting materials is, however, also carried out photochemically in many cases. In addition to the customary processes of solution polymerization in organic solvents, solution polymerization and emulsion polymerization in aqueous systems are of importance in this connection.
Since, as a rule, none of the reactants in the said reactions is capable of absorbing the photochemically active radiation to an adequate extent, it is necessary to add so-called photoinitiators, which do not take part in the desired reaction, but are capable of absorbing irradiated light or UV radiation, transferring the energy thus absorbed to one of the reactants and thus forming active initiator radicals which, in turn, initiate the photopolymerization. Essential criteria for the selection of such initiators are, inter alia, the nature of the reactions to be carried out, the relationship of the absorption spectrum of the initiator to the spectral distribution of energy of the available source of radiation, the solubility of the initiator in the reaction mixture, the stability when stored in the dark of the reaction system to which the initiator has been added and the effect on the end products caused by residues remaining therein of the initiator and/or of the products formed therefrom during the photochemical reaction. In particular, the rate of the reaction depends greatly on the initiator used. There has, therefore, been no lack of attempts to find new initiators which exhibit increased reactivity in their power to initiate the photopolymerization of ethylenically unsaturated compounds or the curing of photopolymerizable systems.
The initiators which havehitherto been employed for the photopolymerization of unsaturated compounds are principally benzophenone derivatives, benzoin ethers, benzil ketals, dibenzosuberone derivatives, anthraquinones, xanthones, thioxanthones, .alpha.-halogenoacetophenone derivatives, dialkoxyacetophenones and hydroxyalkylphenones.
As is known, however, the industrial applicability of many of the substances mentioned is in some cases markedly limited by a number of disadvantages. These include, in particular, the fact that the reactivity in the power of initiating the photopolymerization of ethylenically unsaturated compounds is frequently too low. As well as molecule-specific reactivity, the solubility of the photoinitiators, or the capacity thereof to be incorporated as uniformly as possible, in the photopolymerizable systems frequently plays a decisive part in this respect.
For particular suitability for photopolymerization reactions in aqueous s
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Gehlhaus Jurgen
Kohler Manfred
Ohngemach Jorg
Wehner Gregor
Merck Patent Gesellschaft mit beschrankter Haftung
Reamer James H.
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