Solventless melt process

A solventless PMR resin became known under the designation LARC 160 (15), which could be processed as a hot melt. An exchange of MDA in PMR-15 with a liquid isomeric mixture of di- and trifunctional amines (Jeffamine 22) provided a mixture of monomeric reactants which was tacky at room temperature. In the presence of 3% methanol the resin could be processed via a hot melt process. Unfortunately, the cured resin was inferior with respect to thermal oxidative stability in comparison to PMR-15. 

From a manufacturing standpoint, the interfacial process is capital-intensive to purify the resin solution, isolate and dry the resin, and recycle solvents and brine. With melt transesterification, because it is a solventless process, the only recycle streams that must be dealt with are those related to the recovery of phenol for reuse in the production of DPC. Hence, there is no need to invest in solvent recovery infrastructure with the melt process, and polymer purification units and dryers can likewise be avoided. However, these investments are somewhat diminished by the investment required for the preparation and purification of DPC. 

The adhesives are applied mainly from solvents, some are applied solventless by calendering or as water-based latices. Quite recently solvent-free hot-melt processes have been introduced [229]. 

The synthesis of siloxane-urea block copolymers can be performed either in solution or in the melt at elevated temperatures up to 200 °C. We favor the use of dynamic mixers or extruders to ensure intensive mixing of the components. Surprisingly, adding aminosiloxane and isocyanate to get the block copolymers (2K process) is not the only possibility. We can also add the silanol fluid, the cyclic aminosilane, and the diiosocyanate consecutively to the extruder for a successful solventless preparation of siloxane-urea block copolymers (3K process). 

Asahi Kasei Corporation has developed a solventless, phosgene-free melt production process that uses CO2 as a starting material and employs a reactor that uses gravity, rather than melt mixing equipment, to transfer molten polymer. Chimei-Asahi has implemented the technology in a 50,000 ton per year commercial demonstration plant and has announced plans to expand production at their own plant and with other partners. ... 

Most often acrylic adhesives are applied from solvent or as water-based emulsions. For special applications, like thick double-sided tapes, a solventless process has been developed in which a partially prepolymerized mixture of acrylic monomers is coated onto a liner and subsequently polymerized by UV radiation to form the adhesive [236]. Moreover, acrylic hot-melt adhesives cross-linkable by UV and EB radiation are being developed [237], [238]. 

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