ISO/TS 23885:2022 紙、板紙、グラフィック技術—内側の折り目のコーティング強度の決定 | ページ 2

Foreword

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This document was prepared by Technical Committee ISO/TC 6 Paper, board and pulps, Subcommittee SC 2, Test methods and quality specifications for paper and board, in collaboration with Technical Committee ISO/TC 130, Graphic technology.

Introduction

When folding coated paper during post-press operations, the paper surface can crack in the fold and coating particles can be separated. In the final printed product, the cracking of coatings can cause aesthetic and technical disturbances. Separated particles can occur on both sides of the fold but only remain between sheets of the product, if separated from the inner fold. In case of a good contrast between particles and the printed surface, aesthetic quality problems result, which can cause customer complaints. Cracks can also occur on both sides of the fold but can only result in aesthetic quality problems, if both the fold is still present in the final product and in case of a good contrast between cracked fold and printed surface. Technical quality problems can occur, e.g. on thread-sewn products, if weakened coatings disturb the spine-gluing quality.

To improve the folding behaviour of paper and board, creasing is recommended. For woodfree coated papers (WFC), creasing is typically recommended for grammages of 170 g/m² and higher. Thereby, it should not be neglected that some post-press operations (e.g. folding of signatures) do not allow an effective creasing, and creasing cannot always achieve the desired improvement.

The coating strength in the fold can be determined both in the inner and outer side of a fold. This document contains a test method for the inner fold. This method has been developed in a research project^[3] and is intended to be performed as general paper test to acquire knowledge on a material property and either as a print finishing quality prognosis or a quality acceptance test.

The test consists of four processes: folding of unprinted paper, separation of particles using an impact test device, image capturing of separated particles and image analysis.

1 Scope

This document specifies a test method for the evaluation of the paper coating strength in the inner fold. The test method is intended for single or multiple coated papers up to a thickness of 150 µm that can be folded without creasing.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

3 Terms and definitions

For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

Bibliography