GB/T 22888-2021 English PDF (GBT22888-2021)

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GB/T 22888-2021: Leather - Physical and mechanical tests - Determination of cold crack temperature of surface coatings
GB/T 22888-2021
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 59.140.30
Y 46
Replacing GB/T 22888-2008
Leather - Physical and mechanical tests -
Determination of cold crack temperature of surface
coatings
(ISO 17233:2017, MOD)
ISSUED ON: MAY 21, 2021
IMPLEMENTED ON: DECEMBER 01, 2021
Issued by: State Administration for Market Regulation;
Standardization Administration of the PRC.
Table of Contents
Foreword ... 3 
1 Scope ... 6 
2 Normative references ... 6 
3 Principle ... 6 
4 Apparatus and materials ... 6 
5 Sampling and sample preparation ... 8 
6 Test procedure ... 8 
7 Test report ... 10 
Annex A (Informative) Example for fixing test pieces with adhesive tape ... 11 
Foreword
This Standard is drafted in accordance with the rules given in GB/T 1.1-2009.
This Standard replaces GB/T 22888-2008 "Leather - Physical and mechanical
tests - Determination of cold crack temperature of surface coatings".
Compared with GB/T 22888-2008, in addition to editorial changes, the main
technical changes of this Standard are as follows:
- Delete the description of the number of test pieces in "3 Principle" (see
Clause 3 of the 2008 edition);
- Add the requirement for door of "4.1 Cooled chamber" (see 4.1);
- Add the provision of fixing the test pieces with an adhesive tape in "4.3
Hinged sample holder" (see 4.3);
- Simplify the requirements of "4.4 Press knife"; adjust relevant content to
sampling and sample preparation (see 4.4 and 5.2; 4.4 of the 2008 edition);
- Add "4.6 Adhesive tape" (see 4.6);
- Add instructions for sampling at non-standard locations (see 5.1);
- Refine "5.2 Sample preparation"; modify the number of test pieces prepared
(see 5.2; 5.2 of the 2008 edition);
- Modify Figure 1; add the content of fixing test pieces with adhesive tape
(see Figure 1; Figure 1 of the 2008 edition);
- Modify and refine the test procedure (see 6.1~6.7; 6.1~6.3 of the 2008
edition);
- Modify the judgment of cold crack temperature of surface coatings (see 6.8;
6.4 of the 2008 edition);
- Adjust the test report (see Clause 7; Clause 7 of the 2008 edition).
This Standard uses the redraft law to modify and adopt ISO 17233:2017
"Leather - Physical and mechanical tests - Determination of cold crack
temperature of surface coatings".
Compared with ISO 17233:2017, the structural adjustments of this Standard
are as follows:
- Delete "3 Terms and definitions". The subsequent clause-subclause
numbers are changed in turn (see Clause 3 of ISO 17233:2017);
- Combine 6.2 and 6.3 in ISO 17233:2017 into 5.2 (see 5.2).
The technical differences between this Standard and ISO 17233:2017 and their
reasons are as follows:
- As for the normative references, this Standard has made adjustments with
technical differences, to adapt to the technical conditions of China. The
adjustments are mainly reflected in Clause 2 “Normative references”. The
specific adjustments are as follows:
 Replace ISO 2418 with GB/T 39364, which modifies and adopts the
international standard (see 5.1 and Clause 7);
 Replace ISO 2419 with QB/T 2707, which modifies and adopts the
international standard (see 4.4);
 Delete the reference to EN 15987 (see Clause 2 of ISO 17233:2017).
- Delete "3 Terms and definitions". There is no actual content. It does not
affect understanding and use (see Clause 3 of ISO 17233:2017).
- Modify the requirements for adhesive tape, to avoid ambiguity (see 4.6).
- Add the requirements for sampling at non-standard locations, to meet the
needs of daily testing (or sampling directly from shoes and clothing) (see
5.1).
- Modify the test result presentation method if "the surface coating does not
crack when tested at −30 °C", which is in line with China's custom and to
avoid repetition (see 6.8).
This Standard has made the following editorial changes:
- Modify the expression method of test temperature range (see 4.1 and 4.2);
- Add subclause numbers for sampling and sample preparation (see Clause
5);
- Modify the content of testing at the specific temperature in the note to 6.2
(see 6.2);
- Adjust the sorting of the contents in the test report (see Clause 7);
- Delete the subclause numbers of A.2~A.10 in Annex A (see Annex A of ISO
17233:2017).
Leather - Physical and mechanical tests -
Determination of cold crack temperature of surface
coatings
1 Scope
This Standard specifies a method for determining the cold crack temperature of
surface coatings applied to leather.
This Standard is applicable to the determination of crack temperature of surface
coatings of all leathers which have a surface coating and can be easily flexed.
2 Normative references
The following documents are indispensable for the application of this document.
For the dated references, only the editions with the dates indicated are
applicable to this document. For the undated references, the latest edition
(including all the amendments) are applicable to this document.
GB/T 39364 Leather - Chemical, physical, mechanical and fastness tests -
Sampling location (GB/T 39364-2020, ISO 2418:2017, MOD)
QB/T 2707 Leather - Physical and mechanical tests - Sample preparation
and conditioning (QB/T 2707-2018, ISO 2419:2012, MOD)
3 Principle
A strip of leather test piece is held in a hinged apparatus in a cooled chamber
at a given temperature for a certain period of time. The hinged apparatus is
closed rapidly causing the leather to be folded with the surface coating outwards.
The leather is examined to determine if the surface coating has cracked.
4 Apparatus and materials
4.1 Cooled chamber; the internal height is ≥500 mm; the internal width and
depth are both ≥300 mm; with a rack or other support; the temperature control
range is −30 °C~5 °C; the temperature control accuracy is at least ±2 °C. The
design of the chamber shall allow free circulation of air around the test piece