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Development on New-type Liquid Release Agents for Polyurethane Foam

Author: XiaoYao
Tutor: HeHui; TangFuGen
School: South China University of Technology
Course: Materials Engineering
Keywords: PU foam oil based release agent water based release agent release effect PUfoam surface quality
CLC: TQ328.0
Type: Master's thesis
Year: 2012
Downloads: 25
Quote: 0
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Abstract


Polyurethane (PU) is an important polymer material which has been widely used in manyfields with its unique properties. In PU foam forming process, the mould material is usuallywith high thermal conductivity, such as aluminum, steel, etc. Due to the cohesiveness of theisocyanate component, release agent is needed to prevent materials from cohering on themould.Release agent with fatty acid is a popular organic release agent due to its properties likenon-toxic, good lubrication, stable, low cost and easy to prepare. But it will form a membranewith low strength, which will lead to the crack on the surface of PU foam. Release agent withwax has good release effect, but it will lower the quality of products with its poorcompatibility, unstable property and increasing closed porosity. Release agent with silicon iswidely used in polymer industry for its low surface tension, heat resistance, non-toxic andexcellent release performance. But bubbles will appear on the surface of products, leading toan unpleasant appearance.In this study, oil based liquid release agent products consisted of main releasesubstances(WRA/SRA/PRA), auxiliary release agent, surface active agent and organicadditive agent were developed and applied to the mould release of PU foam, the influence ofrelease agents’ solid content, viscosity, surface tension on the PU foam releasing and porositywas investigated. The results show: when WRA is used alone, the release effect is not ideal, itneed to use with other types of mold release material. SRA can improve the release effect, andthe surface of PU foam has good quality; Release active substance PRA-2can improvesolubility and release effect, but the holes on PU foam surface are seriously closed. Auxiliaryrelease agent can obviously increase the solid content and viscosity, but the dosage should notbe more than1.0%, or the holes will be jammed with the solidification of agent. Organicadditive A can improve the quality of PU foam surface, but it will lower the stability, so thedosage should not be more than0.5%.In addition, water based liquid release agent products consisted of main releasesubstances(WRA-1/SRA), auxiliary release agent, surface active agent, organic additiveagent and water were developed and applied to the mould release of PU foam. The formulasand processes were optimized through orthogonal design method, and the influence ofcomponent contents, emulsification time, surface tension on the releasing of PU foam andporosity was mainly discussed. The results indicated that, the optimum preparation conditionis: the ratio of main release substance(WRA-1:SRA) is5:1, auxiliary release agent dosage is 1.0%, emulsifier concentration is0.2%, organic additive A concentration is0.25%,emulsification time is1.25hr and the surface tension is13.9mN/m; The optimum PU foamopening effect condition is: the ratio of main release substances (WRA-1:SRA) is3:1,auxiliary release agent dosage is0.67%, emulsifier concentration is0.1%, organic additive Aconcentration is0.08%, emulsification time is1.5hr and the surface tension is15.3mN/m.Surface of PU foam was observed by optical microscope and scanning electron microscopy,the results showed that both the two optimum conditions can obtain good release effects andguarantee the quality of the surface of PU foam.

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CLC: > Industrial Technology > Chemical Industry > Synthetic resins and plastics industry > Foam > General issues
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