UV-curable PCDL-based Polyurethane Acrylate Functional Coatings

Polycarbonate diol(PCDL) was firstly synthesized and industrialized by ToagoseiCo.(Japan) in the1980’s. Compared to traditional long-chain diols, PCDL has excellentperformance because of its special structure, and that’s why PCDL attracted attention ofresearchers both in academia and industry. However, because of its later appearance, thereweren’t many research and industrial application on PCDL so far.PCDL is a new material for synthesizing novel polycarbonate based polyurethane, whichhas excellent mechanical properties, thermal stability, abrasion resistance, oxidation resistance,hydrolysis resistance and chemical resistance. They can be used in some special occasions.In this paper, application of PCDL and research on UV-curable coatings are combinedtogether. The main content of the research is synthesis of polycarbonate based polyurethanesand their application on3C products(Computer、Communication and Consumer Electronics).The main work is listed as follows:1. A serious of UV-curable polyurethane-acrylates(PCDL-PUAs) were synthesized fromPCDL with different molecular weights(1000,2000,2600,3000) and different structures(C5/C6structure and C3/C4structure), isophorone diisocyanate(IPDI), methylacrylatehydroxyethyl methacrylate(HEMA) and pentaerythritol triacrylate(PET3A). FT-IR,1H-NMR,GPC and viscosity measurements were used to characterize the PCDL-PUAs’ structure,molecular weights and viscosity, respectively. Mechanical and thermal properties of the curedfilms were characterized with stress-strain test and TGA. The results show that thePCDL-PUA cured films have good tensile properties, flexibility and chemical resistance.A series of soft-touch coating formulas were prepared with PCDL-PUA as matrix resins,1,6-hexanediol diacrylate(HDDA), tripropylene glycol diacrylate(TPGDA), ethoxylatedtrimethylolpropane acrylate(TMP3EOTA), pentaerythritol tetraacrylate(PET4A) as reactivediluents, cross-linked polyurethane particulates(ART PEARL, black,8μm) as flexiblesoft-touch aids, TS-100as matting agent, Irgacure184as photoinitiator and butyl acetate assolvent. And coating performance such as adhesion on ABS and PC, pencil hardness,pendulum hardness and chemical resistance were tested and compared with each other. Theresults show that all the soft-touch coating films have excellent chemical resistance, goodadhesion on PC and full matt surface the soft-touch coatings have good touching feeling.2. A serious of UV-curable fluorinated polycarbonate-based UV-curable polyurethane-acrylates(F-PCDL-PUAs) dispersions were synthesized from PCDL with different molecularweights(500,1000,2000) and IPDI. PET3A was used to impart tri-acrylate functionality tothe end-capping group, and1H,1H,2H,2H-Perfluoro-1-octanol(PFEL) was used toincorporate fluorine segment. FT-IR,1H-NMR and19F-NMR were used to characterize theF-PCDL-PUAs’ structure. Mechanical and thermal properties of the cured films werecharacterized with stress-strain test and TGA. The results show that F-PCDL-PUA cured filmshave better performance on hardness and thermal decomposition than those of PCDL-PUA.F-PCDL-PUAs were used as hydrophobic additives into PCDL-PUA to prepare aneasy-to-clean hydrophobic coating, which can be used in3C products. And coating properties were tested with water-oil contact angle test, surface tension calculation and XPS. The resultsshow that PCDL-PUA film’s water/oil contact angle can be greatly increased and the surfacetension can be greatly decreased by adding F-PCDL-PUA. At the same time, there were notany harmful effects on other coating properties.