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GB/T 39369-2020 English PDF (GBT39369-2020)

GB/T 39369-2020 English PDF (GBT39369-2020)

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GB/T 39369-2020: Leather - Physical and mechanical tests - Determination of water vapour permeability

This Standard specifies the determination method of water vapour permeability of leather. This Standard applies to the determination of water vapour permeability of various types of leather.
GB/T 39369-2020
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 59.140.30
Y 46
Leather - Physical and mechanical tests -
Determination of water vapour permeability
(ISO 14268:2012, MOD)
ISSUED ON: NOVEMBER 19, 2020
IMPLEMENTED ON: JUNE 01, 2021
Issued by: State Administration for Market Regulation;
Standardization Administration of the PEOPLE Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Principle ... 5
4 Instruments and materials ... 6
5 Sampling and sample preparation ... 7
6 Test method ... 8
7 Result expression ... 9
8 Test report ... 10
Foreword
This Standard was drafted in accordance with the rules given in GB/T 1.1-2009. This Standard uses the redrafting method to modify and adopt ISO 14268:2012 ?€?Leather - Physical and mechanical tests - Determination of water vapour permeability?€?.
The technical differences between this Standard and ISO 14268:2012 and the reasons are as follows:
-- Modify the statement of the standardization object in Chapter 1 "Scope"; add the description of the applicability of the standard;
-- With regard to the normative references, this Standard makes technical adjustments to adapt to the technical conditions of China. The
adjustments are concentrated in Chapter 2 ?€?Normative references?€?. The
specific adjustments are as follows:
??? Use GB/T 39364 which modifies and adopts international standards to
replace ISO 2418 (see 5.1 and Chapter 8);
??? Use QB/T 2707 which modifies and adopts international standards to
replace ISO 2419 (see 4.7 and 5.3);
??? Use QB/T 2709 which modifies and adopts international standards to
replace ISO 2589 (see 5.2);
??? Use QB/T 2714 which modifies and adopts international standards to
replace ISO 5402-1 (see 4.10 and 5.2);
-- Add related labels to Figure 1 (see Figure 1);
-- Modify accuracy requirements for "analytical balance" (see 4.4);
-- Add the provision that other equivalents can be used instead of beeswax (see 4.8);
-- Add titles to the first-level articles in Chapter 5 (see Chapter 5); -- Adjust the second paragraph of 5.1 to 5.2 (see 5.2);
-- Add the requirement that "it can be polished with a suitable instrument" (see 5.2);
-- Adjust the last paragraph of 5.2 to a note of 5.2 (see 5.2);
Leather - Physical and mechanical tests -
Determination of water vapour permeability
1 Scope
This Standard specifies the determination method of water vapour permeability of leather.
This Standard applies to the determination of water vapour permeability of various types of leather.
2 Normative references
The following documents are indispensable for the application of this document. For dated references, only the dated version applies to this document. For undated references, the latest edition (including all amendments) applies 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);
QB/T 2709, Leather - Physical and mechanical tests - Determination of
thickness (QB/T 2709-2005, ISO 2589:2002, MOD)
QB/T 2714, Leather - Physical and mechanical tests - Determination of flex resistance (QB/T 2714-2018, ISO 5402-1:2011, MOD)
3 Principle
Fix the sample in an open container bottle that contains a solid desiccant; then, place it in a standard atmosphere with strong fluidity. The air in the container bottle is continuously absorbed by the solid desiccant that rotates with the container bottle. By weighing the mass of the container bottle before and after the test, calculate the water vapour permeability of the sample.
4 Instruments and materials
4.1 Container bottle: the inner diameter of the bottleneck is (30??3) mm; it has a swiveling cover that has a round hole; the diameter of the round hole is equal to the inner diameter of the bottleneck; the bottle height is about 70 mm ~ 90 mm.
4.2 Tester, which includes the following parts:
a) Turntable: it is installed vertically; the speed is (75??5) r/min; it can support the container bottle (4.1); the circular axis of the container bottle is parallel to the axis of the turntable; the distance between the two axes is (67??2) mm.
b) Fan: it is installed on the bottle mouth opposite to the container; it contains 3 fan blades that are 120?? each other; the fan blade plane passes through the extension line of the axis of the vertically-installed turntable. The size of the fan blade is 90 mm ?? 75 mm; the distance BETWEEN the 90 mm
end that is closest to the container bottle mouth AND the container bottle, when it passes the container bottle, is (10??5) mm. The fan speed is (1
400??100) r/min; the direction of rotation is opposite to the direction of the turntable. See Figure 1 for the installation of the turntable and fan.
4.3 Dry allochroic silica gel: the particle size is 2 mm ~ 5 mm; sift out smaller particles and dust. Before the test, dry it in a ventilated oven at (125??5) ??C for about 16 h; then, cool to the test temperature in a closed container bottle. The particle size of silica gel shall be such that it cannot pass through a 2-mm screen; the desiccant that has not been cooled to the test temperature shall not be used. Note 1: It is recommended to use silica gel beads, because compared with silica gel particles, silica gel beads generate less dust.
Note 2: When a large amount of silica gel is placed in a closed container bottle, the cooling rate is slow; the cooling time can be appropriately extended, so as to cool all silica gel to the test temperature.
4.4 Analytical balance: the accuracy is 0.1 mg.
4.5 Timer: the accuracy is 1 min.
4.6 Caliper: the accuracy is 0.1 mm; it can measure the inner diameter of the bottleneck of the container bottle.
4.7 Die cutter: in line with the provisions of QB/T 2707. It can cut a round sample that matches the container bottle mouth, so that it has a better airtightness at the container bottle mouth.
the leather during the sanding process is about 2 N (It can also be polished with a suitable instrument). Then, use the die cutter (4.7) to cut a round specimen in the area of the leather after sanding.
b) According to the provisions of QB/T 2714, bend the specimen 20 000 times; use the die cutter (4.7) to cut a round specimen within the bent area.
c) Use the die cutter (4.7) to directly cut a round specimen.
Note 2: The coating of leather grain can affect the penetration of water vapour into the leather; this effect will be reduced after a slight sanding or bending test. The treatment methods which are specified in a) and b)
are intended to imitate the wear of leather in use. If the specimen does not require pretreatment, directly use method c), which is more
suitable for suede leather or uncoated leather.
5.3 Adjustment of specimens
Adjust according to the provisions of QB/T 2707; test in standard atmosphere. 6 Test method
6.1 Put half a bottle of freshly-dried silica gel in the container bottle (4.1). 6.2 Place the specimen on the container bottle mouth, with the use side facing out.
6.3 Cover the swiveling cover and tighten it, so as to fix the sample and keep the container bottle tightly sealed at the edge.
Note: If necessary, heat the container bottle appropriately, and apply a thin layer of beeswax (4.8) to the bottleneck, so as to seal the specimen and the
bottleneck. If using beeswax to seal, heat the container bottle to (50 ?? 5) ??C before putting the silica gel and the sample.
6.4 Place the container bottle on the turntable and start the instrument. Note: Additional containers and bottles that are specified in 6.1 ~ 6.3 can be used to ensure the balance of the turntable.
6.5 Use a caliper (4.6) to measure the inner diameter of the bottleneck of the second container bottle in two mutually perpendicular directions, to the nearest 0.1 mm. Calculate the average of the diameters in the two directions as the average inner diameter d of the bottleneck of the container.
6.6 After (20??4) h, remove the first container bottle as soon as possible. Put half a bottle of freshly-dried silica gel in the second container bottle; remove the

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