Photocuring industrial applications

Whether radical or cationic initiators are employed depends on the kind of mechanism (free radical or cationic, see Sections 10.2 and 10.3) according to which the monomers polymerize. Industrial applications of photocuring are extremely varied and include the coating of metals (automotive varnishes), the... 

Given that the rate of generation of primary radicals, at a given light flux, is a function of the concentration of photoinitiator, the induction period depends also on initiator concentration. In order to eliminate this induction period of polymerization in industrial scale applications, many photocuring processes are carried... 

Examples of the basic chemistry involved in such polymerizations is shown in Fig. 2. In conventional SLA tools, the laser heam diameter is typically on the order of 100 p, in size and the focused heam has a large depth of focus such that a relatively consistent heam diameter can he maintained as the heam is scanned across large areas of the vat. After the first layer of the object is polymerized, the elevator is lowered down by some small incremental distance into the vat, the liquid resin is allowed to flow over the top of the first layer, and the laser is scanned over the surface to initiate polymerization of the second layer of the part in this new resin layer. This process is repeated over-and-over for each layer of the part until the object is completed. Once the object has been made, the part is raised from the resin vat on the elevator, drained and washed of the unreacted photocurable resin, and subjected to various treatments to finish hardening the object. The first commercially available SLA system was produced by 3D Systems in 1987 and SL is now a widely used technique in industries such as automotive and aerospace. In these industries, SL was originally used to fabricate an array of objects from basic design verification parts to show and tell objects at low cost before significant more expense was invested to mass produce or make any actual application-ready mechani-... 

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