TY - JOUR

T1 - Heat-Induced changes in oil and grease resistant hydroxypropylated-starch-based barrier coatings

AU - Ovaska, Sami Seppo

AU - Geydt, Pavel

AU - Österberg, Monika

AU - Johansson, Leena Sisko

AU - Backfolk, Kaj

N1 - This work has been carried as a part of the Future Biorefinery II (FuBio II) programme of Finnish Bioeconomy Cluster FIBIC Ltd, Finland. TEKES and the industrial partners of the FuBio II programme are acknowledged for their financial support. We also warmly thank Mr. Antti T. Karhu, Ms. Teija Laukala, Ms. Tilly Sainila and Ms. Henna Ukkonen for their contribution to the practical work in this project. The authors also would like to thank Dr. J. A. Bristow for the linguistic revision of the manuscript.

PY - 2015

Y1 - 2015

N2 - The effects of thermal treatment on the stability of the dispersion barrier coating layer and on the mechanical rigidity of the packaging material were studied via oil resistance measurements, microscopic and topographical analyses, and determinations of liquid spreading and absorption. The barrier coatings consisted of hydroxypropylated starch and talc, with and without latex. The coatings showed mainly excellent oil resistance at 23°C and 60°C, but at 100°C the coatings lost their oil resistance, which was considered to be due to the lower oil viscosity and segregation of coating components due to heat. It was found that two consecutive heat treatments at 100°C significantly increased the contact angle of rapeseed oil on coatings containing talc, making the coating more oleophobic. Without talc, the effect of heat treatment on the contact angle was weak. X-ray Photoelectron Spectroscopy data indicated that heat caused latex movement towards the surface. According to Atomic Force Microscopy adhesion images, poor miscibility of latex and starch resulted in local depletion and the agglomeration of latex particles, and reduced the diffusion. The changes in adhesion forces between the tip and coated surfaces were mostly reversible, whereas topographical changes were partly irreversible as an effect of in-situ thermal treatment. Scanning Electron Microscopy indicated that heat treatment of coatings containing latex may also induce self-healing and thus reduce the number of pinholes.

AB - The effects of thermal treatment on the stability of the dispersion barrier coating layer and on the mechanical rigidity of the packaging material were studied via oil resistance measurements, microscopic and topographical analyses, and determinations of liquid spreading and absorption. The barrier coatings consisted of hydroxypropylated starch and talc, with and without latex. The coatings showed mainly excellent oil resistance at 23°C and 60°C, but at 100°C the coatings lost their oil resistance, which was considered to be due to the lower oil viscosity and segregation of coating components due to heat. It was found that two consecutive heat treatments at 100°C significantly increased the contact angle of rapeseed oil on coatings containing talc, making the coating more oleophobic. Without talc, the effect of heat treatment on the contact angle was weak. X-ray Photoelectron Spectroscopy data indicated that heat caused latex movement towards the surface. According to Atomic Force Microscopy adhesion images, poor miscibility of latex and starch resulted in local depletion and the agglomeration of latex particles, and reduced the diffusion. The changes in adhesion forces between the tip and coated surfaces were mostly reversible, whereas topographical changes were partly irreversible as an effect of in-situ thermal treatment. Scanning Electron Microscopy indicated that heat treatment of coatings containing latex may also induce self-healing and thus reduce the number of pinholes.

KW - Composite coatings

KW - Dispersion coatings

KW - Grease barrier

KW - Heat treatment

KW - Hydroxypropylated starch

KW - Talc

UR - http://www.scopus.com/inward/record.url?scp=84951755279&partnerID=8YFLogxK

U2 - 10.3183/npprj-2015-30-03-p488-496

DO - 10.3183/npprj-2015-30-03-p488-496

M3 - Article

AN - SCOPUS:84951755279

VL - 30

SP - 488

EP - 496

JO - Nordic Pulp and Paper Research Journal

JF - Nordic Pulp and Paper Research Journal

SN - 0283-2631

IS - 3

ER -