introduction
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ISO 12625-4-2022 “Toilet paper and sanitary paper products – Part 4: Determination of tensile strength, tensile at break and energy absorption at stretch”

Voluntary, related standards and conformity assessment related ISO specific and express the meaning of terminology as well as in relevant ISO technical barriers to trade (TBT) adhere to the principle of the world trade organization (WTO) information, please refer to the iso.org/iso/foreword.html.

This document has been prepared by the Technical Committee ISO/TC 6 (Paper, board and pulp), SC 2 Subcommittees (Test methods and quality specifications for paper and paperboard) in collaboration with the Technical Committee CEN/TC 172 (Pulp, paper and paperboard) of the European Committee for Standardization (CEN). In accordance with the Technical Cooperation Agreement between ISO and CEN (Vienna Agreement).

The third edition cancels and replaces the technically revised second edition (ISO 12625-4:2016).

The main changes are as follows:

– Includes Appendix B, which describes the method for determining the tensile modulus.

A list of all parts in the ISO 12625 series can be found on the ISO website.

Any feedback or questions regarding this document should be directed to the user’s national standards body. A complete list of these institutions can be found at iso.org/members.html.

ISO 12625-4-2022 “Toilet paper and sanitary paper products – Part 4: Determination of tensile strength, tensile at break and energy absorption at stretch”

1 Range
This document specifies test methods for the determination of tensile strength, maximum tensile strength and tensile energy absorption of tissue and household paper products. It uses tensile test equipment that operates at a constant elongation rate.

It also specifies the calculation methods of tensile index and tensile energy absorption index.

2 Normative references
The following files are referenced in text in a manner that constitutes part or all of the requirements of this document. For dated references, only the cited version applies. For undated references, a new version of the reference (including any revisions) applies.

ISO 186, Paper and board – sampling to determine average quality

ISO 187, Paper, board and pulp – Standard atmospheres for conditioning and testing and procedures for monitoring sample atmospheres and conditioning

ISO 1924-2, Paper and board – Determination of tensile properties – Part 2: constant elongation method (20 mm/min)

ISO 7500-1, Metallic materials – Calibration and verification of static uniaxial testing machines – Part 1: Tensile/compression testing machines – Calibration and verification of force measuring systems

ISO 12625-1, tissue paper and tissue products – Part 1: Vocabulary

ISO 12625-6, Tissue paper and tissue paper products – Part 6: Determination of gram weight

ISO 12625-4-2022 “Toilet paper and sanitary paper products – Part 4: Determination of tensile strength, tensile at break and energy absorption at stretch”

3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 12625-1 and below apply.

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

– ISO Online browsing platform: available at iso.org/obp

– IEC electronic encyclopedia: available at electropedia.org/

3.1 Tensile strength

The maximum tensile force per unit width that a specimen can withstand before breaking

3.2 Tensile index I

Tensile strength (3.1) divided by gram weight

3.3 Stretch at maximum strength

The ratio of the elongation of the specimen over its initial length at the moment when the maximum tension is reached during the tensile test

Note 1: The stretch at maximum force is expressed as a percentage of the initial test span length.

Note 2: This process uses relaxation correction, and the elongation is not measured until the force of (0,25 ± 0,05) N.

ISO 12625-4-2022 “Toilet paper and sanitary paper products – Part 4: Determination of tensile strength, tensile at break and energy absorption at stretch”

3.4 Drawing energy to absorb TEA

Energy absorbed by stretching a specimen under tension per unit surface area until fracture begins (maximum pulling moment)

[Source: ISO 12625-1:2019, 3.53.1.3]

3.5 Tensile Energy absorption index IZ

Tensile energy absorption (3.4) divided by gram weight

[Source: ISO 1924-2:2008, 3.7]

3.6 Tensile modulus M

The slope between the two force points of the tensile force-elongation curve obtained from a constant elongation device

Note 1: In the paper industry, “modulus” refers to the tensile stiffness of the paper, the unit of force per unit width (as opposed to the true “stress” in engineering terms, i.e. force per unit area).

Note 2: This procedure is optional, but if the tensile modulus is required as a measurement for this method, it should be measured and calculated according to the procedure in Annex B.

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