Wednesday, December 31, 2014

Residual monomers and the indoor air lacquers which harden by irradiation with ultraviolet light, i

Træmøbellakker better indoor climate
In a substitution project funded by the Environmental Protection Agency has paint manufacturer Teknos in collaboration with FORCE Technology developed UV-curable coatings for wood furniture, where emissions of allergenic unreacted monomers are substantially reduced. Read the original article here
The aim of the project was to eliminate or greatly reduce the diffusible substances in UV-curing due varnishes for furniture and thus reduce the emission of allergens in the home environment. The work has mainly focused on 1.6 hexandiolakrylat (HDDA). UV-curing furniture varnishes contain more or less unreacted monomers after UV curing, and the project showed that the paint company by a careful choice of the relevant commodities miscible to reduce this emission.
Residual monomers and the indoor air lacquers which harden by irradiation with ultraviolet light, is the main surface in the Danish furniture industry, and especially for the furniture plate. Because UV-curable varnishes and sealers applied with roller or spraying and then cured in special ovens with UV light. Paints are great advantage is an extremely rapid curing after application, which allows the handling and packaging by less than 10 seconds. When the UV-curable varnishes applied to wood, the proportion of these low viscosity varnishes miscible penetrate into the wood, whereby they can not be reached by the UV light. They therefore remain uncured. Further, the paint to a greater or lesser extent, contain substances and binders, which is not completely cross-linked by UV irradiation. These uncured substances can freely diffuse out of the tree and of lakbehandlingen when the furniture on end-user and thereby miscible affect the indoor climate negatively. One of the monomers miscible that are used in UV lacquer formulations, is 1.6 hexandiolakrylat (HDDA). According to Norse SPIN database was used a total of 31.8 tons HDDA the manufacture of paints and varnishes in Denmark in 2007. The allergenic binder is classified miscible as irritant with the risk phrases R36 / 38 (Irritating to eyes and skin) and R43 (May cause sensitization by skin contact). Uncured HDDA can evaporate and expose consumers in the domestic environment. In the Nordic ecolabelling considered health impact of allergic and / or carcinogenic miscible residual monomers to be so great that made specific requirements for the maximum miscible content of residual monomers, for example. Ecolabel criteria for chemical building products. IKEA requires UV varnishes for their wooden furniture maximum can deliver 800 mg / m2 monomers after application.
New prescription for UV-curing cabinet varnish Spray Applied miscible UV varnishes must have a sufficiently low viscosity. For both environmental and hærdningsmæssige reasons, normal lacquer thinners are not used as monomers used instead to dilution of UV varnish. A spray applied UV varnish contains, therefore, typically 35% polymer, 3% photoinitiator, 60% monomer and oligomers, as well as 2% filler. A number of suppliers of UV binders, oligomers and monomers were contacted to obtain information on possible miscible alternative raw materials. On the basis of the alternative raw physical / chemical and environmental characteristics were a testing program designed to find the best color scheme of UV-curable binder, oligomer and monomer. Both the previous miscible and new alternative binders, oligomers and monomers were acrylates. The focus was therefore on increasing the molecular weight of the acrylates used and consequently reduce miscible emissions, but without changing møbellakkens other technical properties, miscible eg. hardenability, hardness and resistance to spills. In laboratory scale was new lacquer formulations with different monomers (16 in total) miscible and various polymers miscible (18 in total) tried. The formulation was kept constant, i.e., same polymer and photo-initiator in one set of tests (with changing monomer) and the same monomer and photoinitiator in the second set of tests (with varying polymer). The first round of testing showed that 32 of the 34 new lacquer formulations hardened sufficiently. Testlakkerne was applied to wood panels and UV-cured, after which the wood panels were cut into precisely metered pieces and extracted by the requirements of IKEA's standard IOS-TM-002nd Via GC analysis was free of extractable residues per monomer. square meter applied UV-cured lacquer measured. Based on the results, the four monomers and the six polymers with the lowest values miscible of residual monomers selected for the second round of testing. In the second round of testing, all combinations of the selected monomers and polymers were tested and the 24 again lacquer formulations were applied to wood panels, UV-cured, sliced and analyzed for extractable free monomers. The results of this second round of testing miscible showed that all 24 formulations gave results of free extractable monomers during IKEA's limit of 800 mg / m2. The lowest value was 8 mg / m 2, and the maximum 527 mg / m 2. Already on the market equivalent paints were applied miscible to wood pieces, miscible UV-cured in the laboratory and analyzed in the same manner, and here the results were respectively 900 (primer) miscible and 1100 (peak

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