Introduction

Holik, Herbert; Moldenhauer, Thomas; Rentrop, Gert-Heinz; Tschudin, Peter F.; Kendenich, Wilhelm Kufferath von

doi:10.1002/9783527652495.ch1

Cited by 2 publications

(1 citation statement)

References 2 publications

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“…Paper can be impregnated, coated, laminated, creped, molded etc. (Holik et al, 2013). One of the technique used to improve the paper and print resistance and its appearance is varnishing process (Majnarić et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Measurements of surface free energy as a tool to asses the effect of varnishing and printing of the paper substrates

Żołek‐Tryznowska¹,

Więcek²

2020

Proceedings - The Tenth International Symposium GRID 2020

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Nowadays, printing products might be finished in various ways. Varnishing process is one of the most popular finishing method which gives various effect, such as mate, glossy etc. However, the varnish layer applied on the paper is very thin, therefore it can be invisible to the naked human eye. The aim of this work was to use contact angle measurement and surface free energy determination as a tool to assess the effect of printing and varnishing process of paper materials. We have used various tools in order to analyses the changes of surface: surface roughness, gloss, water contact angle absorption and surface free energy determination. Those tools were used in order to confirm whether the print has been covered with varnish or not. In this work six various paper substrates were used (glossy, coated and un-coated papers). The printing and varnishing was performed in laboratory conditions using flexographic water-based printing and waterbased varnish. Samples were prepared as follows: paper with ink coating, paper with varnish coating and paper with ink layer and varnish layer on the top. The surface roughness was determinated of all samples and compared. The surface roughness changes were observed for pure paper, overprinted and overvarnished. Next, the gloss of samples prior and after printing and varnishing was measured. The gloss of the samples increases when they are printed or varnished, what is related with properties of ink and varnish. Also, the thickness of ink and varnish layers was determinated. The thickness of the samples increases when the number of layers increases. Finally, the water contact angle was measured and surface free energy was calculated with Owens-Wendt method. Our results reveal the possibility of using various tools in order to confirm the performance of varnishing of the prints. The printing with various colors is always seen by the naked human eye. On the other hand, the varnish layer might be not visible. However, such a comparison is not possible if we do not have the pure paper substrates prior printing or varnish.

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Section: Introductionmentioning

confidence: 99%

Measurements of surface free energy as a tool to asses the effect of varnishing and printing of the paper substrates

Żołek‐Tryznowska¹,

Więcek²

2020

Proceedings - The Tenth International Symposium GRID 2020

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Fold cracking of coated papers: investigation on automated computer-aided visual assessment method

Pál

Dedijer

Koltai

et al. 2021

Nordic Pulp &Amp; Paper Research Journal

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In this paper, white pixel percentage (WPP) value, as an overall measure of fold crack damages, has been analysed with respect to selected parameters of sample preparation and digitalization process, as well as the results of residual tensile strength. The WPP values were derived by an automated image processing algorithm, developed earlier, based on extensive comparative analysis of the existing computer-aided methods. Results indicate that WPP values correlate well with the extent of fold cracks on the coated samples, as far as the used parameters of sample preparation and digitalization are concerned. In the case of correlation with residual tensile strength, results for samples folded in cross direction revealed that the extent of the visually registered fold cracks agree well with the actual damage, while for samples folded in machine direction, the overall strength losses weren’t alarming, although the fold cracks were detected correctly. In addition, results pointed out that the simplest sample placement position (inner angle of 180°) is not applicable for realistic sample representation. Furthermore, scanners could provide a superior image quality in lab conditions, but for industry application, a camera-based solution would be more purposeful, while micrographs are more suitable for traditional visual analysis.

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Introduction

Cited by 2 publications

References 2 publications

Measurements of surface free energy as a tool to asses the effect of varnishing and printing of the paper substrates

Measurements of surface free energy as a tool to asses the effect of varnishing and printing of the paper substrates

Fold cracking of coated papers: investigation on automated computer-aided visual assessment method

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