Preparation Of The Resin For Stereolithography And Modification Study Of Flame-Retarding

Stereolithography(SLA) is characterized by low energy consumption, low cost and high molding precision, which is one of the most important Rapid Prototyping (RP) processes, promoting the great changes in the field of manufacturing. However, the research of photosensitive resin for SLA has started late in China. The monopoly of the resin manufacturers overseas and the lack of series of domestic selected photosensitive resin lead to the restriction of the application of SLA in China. In this case, the development of the high-performance, low-cost resin would have great practical significance to the promotion of rapid prototyping in our country.Starting from hybrid system, a photosensitive resin used for stereolithography was prepared, consisted of bisphenol A type epoxy resin E44 as prepolymer, alicylic epoxy resin CY179 and ethoxylated trimethylolpropane triacrylate SR454 as reactive diluents. By FT-IR and tests of gel content, it is determined that the photosensitive resin could polymerized efficiently when the content of radical initiator 184 was 2%, and the content of cationic initiator PAG202 was 3%. By learning the effect of the hybrid ratio of resin on thethermostability, capability, mechanical properties, curing shrinkage, etc, the best hybrid ratio 1:0.75 was determined. The tensile strength of the cured resin could be up to 57.12MPa, flexural strength could be up to 49.18MPa, elongation at break could be 6.35%, while the impact strength could be 5.55kJ·m-2. Meanwhile, the mechanical properties of the resin could be improved significantly by heat treatment.In order to improve the curing speed and flexibility of the resin formula mentioned above, we synthesized a monofunctional oxetane used as cationic active diluents with trimethylolpropane and diethyl carbonate as raw materials. The structure of the products was tested by FT-IR and 1H-NMR. During the preparation, the effect of ratio of input material, the content of catalysts, reaction time and temperature were studied so that the best synthesis condition was determined. This active diluents mixed in the hybrid resin above could speed up curing rate, reinforce mechanical properties and increase Tg at the same time.For the purpose of improving the flame retardant properties of the photosensitive resin, we also prepared flame retardant photocurable resin composite. By comparing several Halogen-free flame retardant, aluminum diethylphosphinate was thought to be the suitable flame retardant used in UV curing system. The effect of the content of ADP on the UV curing properties was studied by tests of gel content, viscosity and penetration depth. Data from scanning electron microscope (SEM), limit oxygen index (LOI), thermogravimetry (TG), horizontal burning tests and CONE show that retardant properties of the resin modified with ADP was improved significantly compared with pure resin formula while the fire-retardant mechanism was initially revealed and the desired objectives of the basic research was achieved.