GB/T 29848-2018 PDF in English
GB/T 29848-2018 (GB/T29848-2018, GBT 29848-2018, GBT29848-2018)
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Ethylene-vinyl acetate copolymer (EVA) film for PV module
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GB/T 29848-2018: PDF in English (GBT 29848-2018) GB/T 29848-2018
Ethylene--vinyl acetate copolymer (EVA) film for PV module
GB/T 29848-2018
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 31.030
L 90
Replacing GB/T 29848-2013
Ethylene-vinyl acetate copolymer
(EVA) film for PV module
Issued on: December 28, 2018 Implemented on: April 01, 2019
Issued by: State Market Regulatory Administration;
Standardization Administration of PRC.
Table of Contents
Foreword ...3
1 Scope ...6
2 Normative references ...6
3 Terms and definitions ...7
4 Requirements ...8
5 Test methods ...9
6 Inspection rules ...26
7 Packaging, marking, transportation, storage ...27
Foreword
This standard was drafted in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 29848-2013 “Ethylene-vinyl acetate copolymer
(EVA) film for PV module”.As compared with GB/T 29848-2013, the main
technical changes are as follows:
- MODIFY the scope of application (see clause 1; clause 1 of the 2013
version);
- MODIFY the normative reference (see clause 2; clause 2 of the 2013
version);
- ADD the terms and definitions of transparent EVA film, white EVA film,
surface density.DELETE the terms and definitions of EVA film, crosslinking
degree, shrinkage rate (see clause 3; clause 3 of the 2013 version);
- MODIFY the specification requirements, which is divided into transparent
EVA specifications, white EVA specifications.ADD the deviation of surface
density (see clause 4.1; clause 4.1 of the 2013 version);
- ADD the requirements of “no folding mark, no stain” in the appearance
requirements (see clause 4.2; clause 4.2 of the 2013 version);
- ADD the physical performance requirements of transparent EVA.CHANGE
the “indicators” in Table 2 of the 2013 version into the “transparent EVA
indicators”.DELETE the requirements for vinyl acetate content.MODIFY
the transmittance, peel strength, volume resistivity, UV-aging resistance,
high-temperature and high-humidity aging performance.CHANGE the
breakdown voltage strength into electrical strength.ADD the tensile
strength, elongation at break, tracking resistance index, dry-heat aging
performance (optional), UV high-temperature high-humidity aging
performance (optional), PCT aging performance (optional), (see clause 4.3;
clause 4.3 of the 2013 version);
- CHANGE the “requirements for specimen” into “test conditions”.MODIFY
the relevant requirements (see clause 5.2; clause 5.2 of the 2013 version);
- MODIFY the test method of thickness.ADD the test method of the deviation
of the surface density (see clause 5.3; clause 5.3 of the 2013 version);
- ADD the visual inspection method (see clause 5.4; clause 5.4 of the 2013
version);
- ADD the test method of the deviation of surface density (see clause 5.3.2);
Ethylene-vinyl acetate copolymer
(EVA) film for PV module
1 Scope
This standard specifies the terms and definitions, requirements, test methods,
inspection rules, packaging, marking, transportation and storage of ethylene-
vinyl acetate copolymer (EVA) film for photovoltaic module (hereinafter referred
to as EVA film).
This standard is applicable to EVA film for surface crystalline silicon photovoltaic
module.The film module may make reference to this standard.
2 Normative references
The following documents are essential to the application of this document.For
the dated documents, only the versions with the dates indicated are applicable
to this document; for the undated documents, only the latest version (including
all the amendments) are applicable to this standard.
GB/T 1033.1-2008 Plastics - Methods for determining the density of non-
cellular plastics - Part 1: Immersion method liquid pycnometer method and
titration method
GB/T 1040.1-2006 Plastics - Determination of tensile properties - Part 1:
General principles
GB/T 1040.3-2006 Plastics - Determination of tensile properties - Part 3: Test
Conditions for films and sheets
GB/T 1408.1-2016 Electrical strength of insulating materials - Test methods
- Part 1: Tests at power frequencies
GB/T 1410-2006 Methods of test for volume resistivity and surface resistivity
of solid electrical insulating materials
GB/T 2410-2008 Determination of the luminous transmittance and haze of
transparent plastics
GB/T 2790-1995 Adhesives, 180° peel strength test method for a flexible-
bonded-to-rigid test specimen assembly
GB/T 2828.1-2012 Sampling procedures for inspection by attributes - Part 1:
Sampling schemes indexed by acceptance quality limit (AQL) for lot-by-lot
inspection
GB/T 2918-1998 Plastics - Standard atmospheres for conditioning and
testing
GB/T 4207-2012 Method for the determination of the proof and the
comparative tracking indices of solid insulating materials
GB/T 6672-2001 Plastics film and sheeting - Determination of thickness by
mechanical scanning
IEC 61215-2:2016 Terrestrial photovoltaic (PV) modules - Design
qualification and type approval - Part 2: Test procedures
ASTM E313-2010 Standard practice for calculating yellowness and
whiteness indices from instrumentally measured color coordinates
ASTM E424-71 (2015) Standard test methods for solar energy transmittance
and reflectance (terrestrial) of sheet materials
3 Terms and definitions
The following terms and definitions apply to this document.
3.1
Transparent EVA film
A film which uses the EVA resin as the main raw material, is added with
various additives, is formed by melt processing, has transparent appearance,
is used for terrestrial PV assembly.
3.2
White EVA film
A film which uses the EVA resin as the main raw material, is added with white
fillers and various additives, is formed by melt processing, has white
appearance, is used for terrestrial PV assembly.
3.3
Surface density
The EVA film mass per unit area.
According to the determination method of GB/T 1033.1-2008, determine the
density of the EVA film.Determine at least 3 groups for each specimen.Take
the average value.
5.4 Appearance
The appearance of EVA film shall, under the illumination of not less than 1000
lx, be subjected to visual inspection.It requires the observer to have normal
vision or corrected visual acuity of 0.8 or above.Lay the EVA film flatly on a
static workbench.The distance from the observer's eye to the observed
specimen does not exceed 0.6 m, to make observation at an angle of 45° to the
workbench.Check whether the film is flat, free of creases, stains, visible
impurities, or bubbles, has clear embossing.
5.5 Determination of physical performance
5.5.1 Luminous transmittance
5.5.1.1 Instrumentation
Spectrophotometer: It is equipped with an integrating sphere, the diameter of
which shall be greater than 90 mm.
5.5.1.2 Preparation of specimen
Take a piece of EVA film which has a size of 50 mm × 50 mm.From top down,
sequentially superimpose the front-panel material, the non-adhesive film, the
EVA film, the non-adhesive film, the back-panel material.Place it into the
vacuum laminating machine, allowing the front-panel to face downwards.
According to the curing temperature and time as required for the product, carry
out curing and crosslinking.Then take it out.Place it into a desiccator to cool it
to room temperature.Prepare for use.For the specimen as taken from the non-
adhesive film, the upper and lower surfaces shall be flat; the thickness shall be
uniform; the crosslinking degree reaches above 75%.The number of
specimens for each group is not less than 3.
Note 1: The front-panel material and the back-panel material shall be consistent
with the materials used in the actual PV modules.
Note 2: The non-adhesive film does not react with EVA film during the
lamination process.It can withstand temperatures above 200 °C.It may use the
surface-untreated ETFE film; the thickness of which ranges 50 μm ~ 125 μm.
5.5.1.3 Test method
Test the specimen according to the spectrophotometer method of GB/T 2410-
2008.Set the wavelength range of the spectrophotometer to be 290 nm ~ 1100
nm.Respectively calculate the average values of the luminous transmittances
W2 - The mass of the specimen-contained bag, in grams (g);
W3 - The mass of the specimen package after solvent extraction and drying,
in grams (g).
5.5.3.2 Differential scanning calorimetry (DSC method)
5.5.3.2.1 Instrumentation
The instrumentation is as follows:
a) Micro-electronic balance: Accurate to 0.01 mg; the range is greater than 1
g;
b) Differential scanning calorimeter (DSC): The temperature accuracy is ±
0.05 °C; the calorimetric accuracy is ± 0.2%; the temperature sensitivity is
10 μW; the temperature measurement repeatability is ±0.1%; the
temperature-rising rate is 5 °C/min ~ 30 °C/min; the temperature
measurement accuracy is ±0.1 °C; the baseline curvature and baseline
drift are less than 10 μW.
5.5.3.2.2 Preparation of specimen
The specimen preparation process is as follows:
a) Respectively cut the un-laminated EVA film and the EVA film as laminated
according to 5.5.1.2 into 7 mg ~ 10 mg of test samples (hereinafter
referred to as uncured sample and cured sample, respectively).The
accuracy of weighed sample is within 1%.Prepare 3 sets of specimens;
b) Place the uncured and cured samples in two sample crucibles,
respectively.Press and pack it on the sample packaging machine.
5.5.3.2.3 Test method
The test method is as follows:
a) Turn on the DSC instrument.Set the parameters.The test shall be carried
out under the atmosphere of protective gas (including nitrogen, helium,
argon).The gas flow rate is 20 mL/min ~ 50 mL/min.The initial
temperature is 30 °C.The termination temperature is 250 °C.The
temperature-rise rate is 10 °C/min;
b) Put the sample crucible and the reference crucible into the furnace,
respectively.Close the furnace cover;
c) From the setting interface of operating software, input the mass of the
sample.After confirming the test conditions, click the “startup” to run the
According to the test procedure as specified in GB/T 1040.1-2006, carry out the
test at a tensile speed of 100 mm/min ± 10 mm/min.Test at least 5 specimens.
According to the formula as specified in GB/T 1040.1-2006, calculate the tensile
strength and elongation at break of the specimen.Calculate the tensile strength
and elongation at break of each specimen.Take the average value.
5.5.5 EVA/glass peel strength
5.5.5.1 Instrumentation and supporting materials
Instrumentation and supporting materials are as follows:
a) Tensile testing machine;
b) Laminating machine;
c) Ultra-white embossed tempered glass: The surface shall be clean and flat,
without stain; the thickness is 3.2 mm; the transmittance in the 380 nm ~
1100 nm band is above 91.5%;
d) Flexible back-panel: The surface shall be clean and flat, without wrinkles,
scratches, delamination, air bubbles, etc.The transmission rate of water
vapor shall be less than 2.0 g/(m2 • 24 h).The back-panel itself does not
separate between layers.The breaking force is greater than 300 N;
e) Floating-plate semi-tempered glass: The surface shall be clean and flat,
without stain; the thickness is 2.5 mm.
5.5.5.2 Preparation of specimen
The procedures for the preparation of specimens are as follows:
a) Prepare two pieces of uncured EVA film, one piece of glass, one piece of
flexible back-panel which have a size of 300 mm × 150 mm;
b) Superimpose the glass/EVA film (two pieces)/flexible back-panel
sequentially.Put it in the vacuum laminating machine.According to the
curing temperature and time as required for the product, carry out curing
and cross-linking.In the laminated and cured sample, the EVA film shall
not have air bubbles.Prepare 3 specimens;
c) In the width direction, at an interval of 5 mm, cut the flexible back-
panel/EVA film layer into the specimens which have a width of 10 mm ±
0.5 mm.Use them for the test of peel force between EVA and glass.
Note: The glass for preparing the transparent EVA sample is ultra-white
embossed tempered glass.The glass for preparing white EVA sample is floating
flat semi-tempered glass.The non-tin surface is facing EVA.
The instrumentation is as follows:
a) Pressure resistance tester;
b) Thickness gauge, which has a minimum scale of 0.01 mm.
5.5.8.2 Preparation of specimens
Take a piece of 200 mm × 200 mm uncured EVA film.Follow the requirements
of 5.5.1.2 to laminate it.Trim the crosslinked EVA film.Cut off the specimen
whose surface is flat and free from air bubbles and impurities and which has a
size of 100 mm × 100 mm.Prepare 5 specimens.
5.5.8.3 Test method
The test procedure is as follows:
a) Use a thickness gauge to measure the specimen’s thickness.Make 3
measurements at different locations.Take the average value as the
thickness value of the specimen;
b) According to the provisions of GB/T 1408.1-2016, at power frequency, test
the breakdown voltage of the specimen; calculate the electrical strength
of the specimen.For the test results, take the average of 5 specimens.
5.5.9 Tracking resistance index
5.5.9.1 Preparation of specimen
Take uncured EVA film.Follow the requirements of 5.5.1.2 to laminate it.Cut off
the specimen which has a size of 30 mm × 30 mm from the location where the
surface is flat and free from air bubbles and impurities.Superimpose multiple
samples, to obtain one group of specimens which have a thickness of at least
3 mm.Prepare 5 groups of specimens.
5.5.9.2 Test method
According to the provisions of GB/T 4207-2012, prepare the solution A.On the
surface of the specimen, at a rate of 30 s ± 5 s, add 50 drops or 100 drops of
the solution A.Observe and record the appearance of the 5 groups of
specimens.According to the provisions of GB/T 4207-2012, judge the tracking
resistance index (PTI) or the contrast tracking index (CTI) of the specimen.
5.5.10 UV-aging resistance
5.5.10.1 Purpose
Use the ultraviolet accelerated aging test to check the performance of the
atmospheric light-aging performance of the cured EVA film which is exposed to
5.5.10.5 Test procedure
It is according to the provisions of 4.10 of IEC 61215-2:2016.The test procedure
is as follows:
a) Allow the glass side of the specimen to face the light source, place it in the
effective irradiation area of the UV-aging test chamber.Test conditions are
as follows:
1) Ultraviolet spectral distribution: The irradiation intensity between the
wavelengths of 280 nm and 400 nm is 50 W/m2 ~ 150 W/m2.The
illumination uniformity at the surface of the test sample is within 15%.
Irradiation in the 280 nm ~ 320 nm band accounts for 3% ~ 10% of the
total irradiation;
2) While the ultraviolet irradiation is being performed, the surface
temperature of the specimen in the test chamber is maintained at 60 °C
± 5 °C;
3) Accumulation of irradiation power: It is accumulated according to the
actual exposure of the specimen’s surface.
b) Test time: It is calculated based on the accumulated dosage of the
radiation power, 120 kWh/m2.
c) After the test, remove the specimen.At an open environment of
temperature 23 °C ± 5 °C and relative humidity of less than 75%, restore
it for 2 h ~ 4 h.Check the appearance.There shall be free from
appearance defects.The light-exposed surface of the white EVA is free
from embrittlement or powdering.
d) Respectively for the laminated specimen before and after the test, follow
the requirements of ASTM E313-2010 to measure the yellowing index YI.
For each specimen, make measurement for at least 3 points.The
yellowing index YI of the specimen is taken as the average of the
measured points.Record the difference between the yellowing index YI
after aging and the yellowing index YI before aging, which is the yellowing
index ΔYI.For laminates which use the flexible back-panel materials, use
the test method of 5.5.5 to measure the peel strength between the film
and the glass in the laminates before and after the tests.
5.5.11 High-temperature high-humidity aging performance
5.5.11.1 Purpose
Measure the aging resistance of the cured film under high-temperature high-
humidity constant damp heat conditions.
it for 2 h ~ 4 h.Check the appearance.There shall be free from
appearance defects.
d) Respectively for the laminated specimen before and after the test, follow
the requirements of ASTM E313-2010 to measure the yellowing index YI.
For each specimen, make measurement for at least 3 points.The
yellowing index YI of the specimen is taken as the average of the
measured points.Record the difference between the yellowing index YI
after aging and the yellowing index YI before aging, which is the yellowing
index ΔYI.For laminated specimens which use the flexible back-panel
materials, use the test method of 5.5.5 to measure the peel strength
between the film and the glass in the laminates before and after the tests.
5.5.14 PCT aging performance (optional item)
5.5.14.1 Purpose
Determine the aging resistance of the cured film under constant damp heat
conditions of high-temperature, high-humidity, high-pressure.
5.5.14.2 Instrumentation and supporting materials
Instrumentation and supporting materials are as follows:
a) High-temperature high-pressure cooking aging test chamber;
b) Colorimeter;
c) Tensile testing machine;
d) Supporting material, same as 5.5.10.3.
5.5.14.3 Preparation of specimens
Take two pieces of 300 mm × 300 mm EVA film.Follow the requirements of
5.5.10.4 to prepare the laminated specimens.Prepare 3 laminated specimens.
5.5.14.4 Test procedure
The test procedure is as follows:
a) Put the specimen into the PCT aging test chamber.Set the test conditions:
Temperature 121 °C ± 0.5 °C, relative humidity 99% ~ 100%;
b) Test time: 48 h;
c) After the test, remove the specimen.At an open environment of
temperature 23 °C ± 5 °C and relative humidity of less than 75%, restore
it for 2 h ~ 4 h.Check the appearance.There shall be free from
of the product, which may affect the performance of the product;
c) When the production is restored after suspension for more than 1 year or
when it is produced by new machine;
d) When the national quality supervision and inspection agency proposes the
requirements for type inspection;
e) When the exit-factory inspection result is significantly different from the
previous type inspection result.
7 Packaging, marking, transportation, storage
7.1 Packaging
7.1.1 The product is in the unit of rolls.Each roll of products uses moisture-
proof and dust-proof package.
7.1.2 Each roll of product is accompanied by a certificate of conformity, the
items include: product model, specification, batch number, production date.
7.2 Marking
Each box of products shall, during exit-factory, be marked of the name of the
manufacturer, product name, model, specification, quantity, date of
manufacture, implemented standards.
7.3 Transportation
The transportation of products shall be protected from light, heat, moisture,
throwing or stacking in open air.It shall not bend or damage the product.
7.4 Storage
7.4.1 Storage location
The product shall be stored indoors.The temperature is controlled within the
range of 0 °C ~ 30 °C.The relative humidity is less than 60%.Avoid direct
exposure to sunlight.Do not be close to heating equipment or expose to dusty
places.
7.4.2 Storage requirements
Storage requirements are as follows:
a) Before unpacking, check the packaging box of the stored product, which
shall be intact;
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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