Título: | OPERABILITY LIMITS OF THE CURTAIN COATING PROCESS | ||||||||||||||||||||||||||||||||||||||||
Autor: |
MELISA YVONE ZAMBRANO BECERRA |
||||||||||||||||||||||||||||||||||||||||
Colaborador(es): |
MARCIO DA SILVEIRA CARVALHO - Orientador |
||||||||||||||||||||||||||||||||||||||||
Catalogação: | 20/ABR/2010 | Língua(s): | PORTUGUESE - BRAZIL |
||||||||||||||||||||||||||||||||||||||
Tipo: | TEXT | Subtipo: | THESIS | ||||||||||||||||||||||||||||||||||||||
Notas: |
[pt] Todos os dados constantes dos documentos são de inteira responsabilidade de seus autores. Os dados utilizados nas descrições dos documentos estão em conformidade com os sistemas da administração da PUC-Rio. [en] All data contained in the documents are the sole responsibility of the authors. The data used in the descriptions of the documents are in conformity with the systems of the administration of PUC-Rio. |
||||||||||||||||||||||||||||||||||||||||
Referência(s): |
[pt] https://www.maxwell.vrac.puc-rio.br/projetosEspeciais/ETDs/consultas/conteudo.php?strSecao=resultado&nrSeq=15502&idi=1 [en] https://www.maxwell.vrac.puc-rio.br/projetosEspeciais/ETDs/consultas/conteudo.php?strSecao=resultado&nrSeq=15502&idi=2 |
||||||||||||||||||||||||||||||||||||||||
DOI: | https://doi.org/10.17771/PUCRio.acad.15502 | ||||||||||||||||||||||||||||||||||||||||
Resumo: | |||||||||||||||||||||||||||||||||||||||||
Curtain coating is one the preferred methods for precision multi-layer coatings at
high speeds. Curtain coating belongs to the class of premetered coating methods.
Liquid falls as a sheet, or curtain, freely over a considerable height and under
the action of gravity before it impinges onto the substrate being coated. Edge
guide are needed to maintain at specific width of the falling curtain. Precision
curtain coating was originally developed for multi-layer photographic film but
its use has expanded to many different applications such as optical films and
specialty papers. Some advantages of this process include very high coating
speeds, adaptability to a wide range of liquids and flexibility to apply thin liquid
layer to irregular surfaces. The operability limits of the process are set by different
flow instabilities in the coating bead, such as air entrainment, low speed heels and
curtain pulling, and by curtain breakup. The goal of this research is to analyze
these operability limits by theory and experiments. The focus is to determine
the effect of operating parameters; edge guides design and polymer additives on
the coating solution on the bead configuration and liquid curtain breakup. The
conservation mass and momentum equations with the boundary conditions were
used to describe the flow. The equations were solved all together by Galerkin’s
method with finite element basis functions and non-linear system solved by
Newton’s method. Theoretical results show the bead configuration, including heel
formation and curtain pulling as a function of web speed, curtain height and flow
rate. Theoretical predictions will also be extended to include viscoelastic behavior
of the coating liquid. This results was compared with experimental results to
obtain the coating windows for fixed parameters. The visualization results show
the critical condition at which a viscoelastic liquid curtain breaks was determined
as a function of the rheological properties of the coating liquid. The results show
that the viscoelastic properties can affect the force balance in the curtain flow.
High extensional viscosity liquids can drastically reduce the minimal flow rate to
create more stable curtains.
|
|||||||||||||||||||||||||||||||||||||||||
|