Ethylene-Vinyl Acetate:Photovoltaic module encapsulated with ethylene vinyl acetate (EVA) film

Foreword

This standard was drafted in accordance with the rules given in GB/T 1.1-2009.

Please note that some of the contents of this document may involve patents. The issuing agency of this document does not assume responsibility for identifying these patents.

This standard was proposed and managed by the National Semiconductor Equipment and Materials Standardization Technical Committee (SAC/TC 203).

This standard was drafted by: Hangzhou Forster Photovoltaic Materials Co., Ltd., Wuxi Suntech Solar Power Co., Ltd., Changzhou Trina Solar Energy Co., Ltd., Yingli (China) Green Energy Co., Ltd., National Photovoltaic Product Quality Supervision and Inspection Center, Lekai Film Co., Ltd., Wenzhou Rui Sunshine Vol., Ltd., Zhejiang Lanshao Photovoltaic Materials Co., Ltd., Zhuji Fenghua Plastics Technology Co., Ltd.

The main drafters of this standard are: Lin Jianhua, Zhou Guangda, Hou Hongbing, Sang Yan, Chen Xiang, Yang Chufeng, Sun Yuhai, Wang Zhaoyun, Wang Xiuxiang, Wu Jianguo, Wang Li, Zhan Xianguang, Long Zhongnan and Zhou Junhua.

1 Scope

This standard specifies the terms and definitions, requirements, test methods, inspection rules, packaging, marking, transportation and storage of Ethylene Vinyl Copolymer (EVA) film for photovoltaic module packaging (hereinafter referred to as EVA film).

This standard applies to the Ethylene-Vinyl Acetate copolymer (EVA) as the main raw material, add a variety of additives, the melt processing molding, for the packaging of terrestrial photovoltaic modules film.

2 normative references

The following documents are indispensable for the application of this document. For dated references, only dated versions apply to this document. For undated references, the latest version (including all amendments) applies to this document.

GB/T 1033.1-2008 Plastics - Determination of the density of non-cellular plastics - Part 1: Immersion method, liquid pycnometer method and titration

GB/T 1410-2006 Test method for volume resistivity and surface resistivity of solid insulating materials

GB/T 1695-2005 Test method for breakdown voltage strength and withstand voltage of vulcanized rubber

GB/T 2410-2008 Determination of Transparency and Haze of Transparent Plastics

GB/T 2423.3-2006 Environmental testing for electric and electronic products Part 2: Test methods Test Cab: Constant damp heat test

GB/T 2790 adhesive 180° peel strength test method flexible material to rigid material

GB/T 2828.1 Count Sampling Inspection Procedures Part 1: Batch Inspection Sampling Plans Retrieved by Acceptance Quality Limit (AQL)

Standard environment for GB/T 2918 plastic sample conditioning and testing

GB/T 6672 Determination of thickness of plastic film and book sheet - Mechanical measurement method

GB/T 19394-2003 Photovoltaic (PV) module UV test

Standard practice for calculating yellowness and whiteness indices from instrumentally measured color coordinates

3 Terms and Definitions

The following terms and definitions apply to this document.

3.1

EVA film Copolymer Ethylene Vinyl Acetate (EVA) film

EVA (ethylene vinyl acetate copolymer) resin as the main raw material, add a variety of additives, the melt processing molding, for the packaging of terrestrial photovoltaic modules film.

3.2

Cross-linking degree

Used to characterize the degree of cross-linking of polymer chains.

Note: The degree of cross-linking of EVA film is generally represented by the gel content, that is, the percentage of the cross-linked polymer chain that accounts for the total amount of EVA.

3.3

Shrinkage rate

The percentage of the original length after the material has been treated (water immersed, heat set or resin treated).

4 requirements

4.1 Specifications

The specifications of single-roll products should comply with Table 1.

4.2 Appearance

The appearance should be smooth, no visible impurities, no bubbles, and clear embossing.

4.3 Physical Performance

The physical properties of the product should comply with Table 2.

5 test methods

5.1 sampling methods

After removing the outer layer of the tested EVA film roll for 3 to 5 layers, take the EVA film section wound in the middle of the roll as the test sample film.

5.2 sample requirements

5.2.1 Sample Condition Adjustment and Test Environment

Sample state adjustment and test environment According to the provisions of GB/T 2918, ambient temperature 23 °C ± 2 °C, relative humidity 50% ± 5%, the sample under the conditions of the test set aside not less than 24h, and under this condition experimenting.

5.2.2 back plate for sample

The backsheets used in this standard shall meet the following requirements: The surface is a fluorine-containing material, the moisture vapor transmission rate is less than 2.5g/(m2·d), and the irradiation intensity is 120kW·h/m2. After the test, the change in the yellow index of the backsheet itself was less than 2.0, Titanium Dioxide,and no separation between layers occurred on the backsheet itself after a constant damp-heat aging test.

5.3 Measurements

5.3.1 Thickness

According to GB/T 6672 determination method, with an accuracy of 0.01mm thickness gauge determination. At least 5 points are measured in the direction of the amplitude and averaged.

5.3.2 Density

According to GB/T 1033.1-2008 determination method, the density of Eva Ethylene film was measured. Each sample at least measured 3 groups, averaged.

5.4 Appearance Inspection

Visually inspect the film for transparency, color, bubbles, impurities, perforations, and cracks.

5.5 Determination of physical properties

5.5.1 Determination of vinyl acetate vinegar (VA)

5.5.1.1 Thermogravimetric Analyzer (TGA) Method (Arbitration Method)

5.5.1.1.1 Instruments and Equipment

Thermogravimetric Analyzer (TGA)

5.5.1.1.2 Test procedure

The test process is as follows:

a) start TGA instrument, Pvc Resin ,open the software, set the TGA test program: the starting temperature is 40 °C, constant temperature 3min-5min, the termination temperature is above 450 °C, the heating rate is 10 °C / min-20 °C / min;

b) Put a 5mg-12mg EVA film sample on a clean empty sample pan after peeling and load the sample pan. After the balance reading is stable, run the temperature increase program.

c) After the test is finished, heat loss curve of the sample is processed, and the mass fraction of the first step change of the thermal weight loss curve is recorded, that is, the Acetic Acid mass fraction of the vinyl acetate vinegar breaks in the EVA molecule.

5.5.1.1.3 Test results

According to equation (1), calculate the VA content in the EVA film, and take the arithmetic average of the three groups of samples, accurate to 0.1%.

5.5.1.2 Hydrolysis and back titration

The hydrolysis and back titration methods are shown in Appendix A.

5.5.2 Determination of Transmittance

5.5.2.1 Instruments and Equipment

Ultraviolet spectrophotometer with integrating sphere, the integrating sphere diameter must be greater than 90mm.

5.5.2.2 Sample Preparation

One piece of EVA film with a size of 50mm x 50mm and one piece of glass with a size larger than 50mm x 50mm, two pieces of no-mucosa, one piece of back plate for sample, glass/non-mucosa/EVA film/non-mucosa/sample After laminating the back plates one by one, they are placed in a vacuum laminator.

Curing cross-linking is carried out according to the product's required curing temperature and time, then removed and placed in a desiccator to cool to room temperature. No less than 3 samples per group.

5.5.2.3 Test procedure

The specimens were tested by the spectrophotometer method of GB/T 2410-2008, and the transmittance curves of 290 nm-1100 nm were taken.

At least 3 samples of each group were tested and the test results were averaged.

5.5.3 Determination of degree of crosslinking

5.5.3.1 Principle

The EVA film is cured by heating to form crosslinks, and the uncrosslinked portion of the sample is extracted with xylene solvent to determine the degree of crosslinking.

5.5.3.2 Instruments and Equipment

The required equipment is as follows:

a) A three-neck round bottom flask with a capacity of 500 mL with a 24# grinding mouth;

b) reflux condenser with 24# grinding mouth;

c) electric heating jacket equipped with a temperature controller;

d) An electronic balance with an accuracy of 0.001g;

e) vacuum oven;

f) Stainless steel wire mesh bag: Cut a 120 mesh stainless steel screen with a size of 120mm x 60mm, fold it into 60mm x 60mm, fold the two sides into 5mm twice and fix it inward to make the top opening size as 60mm x 40mm mesh bag.

5.5.3.3 Reagents

Xylene (AR grade).

5.5.3.4 Sample Preparation

Take 2 pieces of EVA film with dimensions of 75mm x 150mm, 1 piece of glass, and 1 piece of sample back plate. Laminate the glass/two-layer EVA film/sample back plate one by one. Inside the machine, the curing cross-linking is performed according to the curing temperature and time required by the product, then removed, and the backing plate on the sample is peeled off, and about 1 g of the cross-linked and cured EVA film is removed from the glass with a blade in the middle of the sample. , and EVA film cut into 3mm × 3mm below the small particles. Take 2 samples for each group.

5.5.3.5 Test procedure

The test process is as follows:

a) The stainless steel wire mesh bag is washed, dried, weighed to WI (accurate to 0.001g);

b) take a sample of 0.5g ± 0.01g, put a person in a stainless steel mesh bag, make a sample package, weighing W2 (accurate to 0.001g);

c) Seal the sample bag with a thin wire, mark it, insert it from the side port of the three-necked flask and seal it with a rubber stopper. Add 1/2 volume of xylene solvent to the flask to immerse the sample packet in the solvent. in. Heated to about 140 °C, the solvent boiled reflux 5h. Reflow rate to maintain 20 drops / min-40 drops / min;

d) After the reflux is completed, take out the sample bag and suspend to remove the solvent droplets. Then placed in a vacuum oven, the temperature was controlled at 140 ° C, drying 3h, completely remove the solvent;

e) Remove the sample from the oven, remove the wire, and place it in a desiccator for 20 minutes. Remove it and weigh it as W3 (accurate to 0.001g).

5.5.3.6 Test results

According to equation (2) to calculate the degree of cross-linking, take the arithmetic mean of the two groups of samples, accurate to 0.1%.

5.5.4 Determination of Peel Strength

5.5.4.1 Sample Preparation

The sample preparation procedure is as follows:

a) Prepare 2 pieces of EVA film with dimensions of 300mm x 150mm, 1 piece of clean glass with 3mm thickness, and 1 piece of back plate;

b) After the glass/two-layer EVA film/backplane is stacked in order, the vacuum laminator is placed and curing cross-linked according to the curing temperature and time required by the product. Laminated and cured EVA film should have no bubbles on the surface. 3 samples for each group;

c) The EVA film/backplane layer was cut into a sample having a width of 10 mm±0.5 mm every 5 mm in the width direction for measuring the peeling force between the glass and the EVA film.

5.5.4.2 Test procedure

According to the GB/T 2790 test method, the peel force between the EVA film and the glass was measured on a tensile machine at a pulling speed of 100 mm/min.

5.5.4.3 Test results

The peel strength was calculated according to equation (3). The arithmetic average of the three groups of samples was taken to the nearest 0.1 N/cm.

5.5.5 Determination of Shrinkage

5.5.5.1 Sample preparation

Take a piece of EVA film and cut the sample according to the longitudinal length of 200mm and transverse width of 100mm. Take 3 samples for each group.

5.5.5.2 Test procedure

First place the sample on the glossy surface of 3mm thick suede glass, place it in an oven preheated to 120°C or on the surface of the hot plate of the laminator. After heating for 3 minutes, remove the sample and cool it to room temperature. Length L (in mm) and width B (in mm)

5.5.5.3 Test Results

The shrinkage rate was calculated according to equations (4) and (5), and the arithmetic average of the three groups of specimens was taken to the nearest 0.1%.

5.5.6 Determination of volume resistivity

5.5.6.1 Instruments and Equipment

High resistance tester.

5.5.6.2 Sample Preparation

Take one piece of EVA film with a size of 80mm×80mm and one piece of glass with a size larger than 80mm×80mm, two pieces without a mucous membrane, one piece of back plate for sample, press glass/non-mucosa/EVA film/non-mucosa/sample After superimposing the back plates one by one, the vacuum laminator is released, and curing cross-linking is performed according to the curing temperature and time required by the product, so that the cross-linking degree of the sample is greater than 75%. Take 3 samples for each group.

5.5.6.3 Test procedure

According to the requirements of GB/T 1410-2006, the volume resistivity of the sample is tested. The test result is to take the arithmetic mean of the three groups of samples.

5.5.7 Determination of breakdown voltage strength

5.5.7.1 Instruments and Equipment

The required equipment is as follows:

a) Power frequency power supply;

b) high voltage transformers;

c) regulator transformer;

d) Overcurrent relays;

e) Electrode.

5.5.7.2 Sample preparation

Take two pieces of EVA film with a size of 80mm×80mm and one piece of glass with a size larger than 80mm×80mm, two pieces without a mucous membrane, and one piece of a back plate for samples. Press glass/no mucous membrane/two-layer EVA film/no mucous membrane After the sample is laminated with the back plate in turn and placed in a vacuum laminator, curing cross-linking is performed according to the curing temperature and time required by the product, so that the cross-linking degree of the sample is greater than 75%. The cross-linked EVA film was then trimmed, and a circular sample with a diameter of 50 mm±1 mm was cut out, and the average thickness of the sample was measured with a thickness gauge. Take 3 samples for each group.

5.5.7.3 Test procedure

According to the provisions of GB/T 1695-2005, the breakdown voltage strength test of the sample. The test results take the arithmetic mean of the three groups of samples.

5.5.8 Ultraviolet accelerated aging test

5.5.8.1 Purpose

The UV accelerated aging test was used to examine the photo-aging resistance of the cured EVA film exposed to the atmosphere.

5.5.8.2 Instruments and Equipment

The required equipment is as follows:

a) UV accelerated aging test box;

b) Laminator;

c) Spectrophotometer;

d) Rally machine.

5.5.8.3 Sample preparation

Cut back the glass, EVA film and sample back plate according to the size of the test rig, and stack the glass/two-layer EVA film/sample back plate one by one, and cure and crosslink according to the curing temperature and time required by the product. Samples were prepared.

5.5.8.4 Test procedure

According to the requirements specified in GB/T 19394-2003 UV irradiation aging test.

a) Place the sample in a UV aging test box, where the irradiance of the UV light does not exceed 120 W/m2. The test conditions are as follows:

1) The sample surface temperature 60 °C ± 5V;

2) Irradiation intensity: When the wavelength is in the range of 280nm-320nm, it is 6kW·h/m2;

When the wavelength is in the range of 280nm to 400nm, it is 60kW·h/m2°

3) Accumulation of irradiation power: accumulate according to the actual irradiation dose on the surface of the sample, and calibrate the UV power with an irradiation meter at least every 30 kW·h/m2.

b) Before and after the test, the yellow index shall be measured according to ASTM E313. The number of each sample shall be not less than 3 points. The yellow index of the sample shall be the average of the measured points. After the sample is heated at an ambient temperature of 23 °C ± 2 °C for 60 min, take a distance of at least 10 mm from the edge of the specimen. Measure the peel strength between the EVA film and the glass according to the test method of 5.5.4. Record the EVA film separately. The difference between the peel strength and the yellow index before and after aging of the glass.

5.5.9 Constant Humidity Aging Test

5.5.9.1 Purpose

The aging resistance of the cured EVA film under constant moist heat conditions was measured.

5.5.9.2 Sample Preparation

Take two pieces of EVA film with a size of 300mm×300mm, sandwich it between the glass with the size of 300mm×300mm and the backplate for the sample, cure and crosslink according to the curing temperature and time required by the product, and prepare the test. kind.

5.5.9.3 Test procedure

According to the test method of GB/T 2423.3-2006 heat aging test. The test process is as follows:

a) Place the sample in a constant test chamber and set the test conditions: temperature 85 °C ± 2 °C, relative humidity 85% ± 5%;

b) Remove the sample when the heat and humidity aging time reaches 1000h;

c) Before and after the test, the yellow index shall be measured according to ASTM E313. Each sample shall be measured at not less than 3 points. The yellow index of the sample shall be the average of the measured points. After the sample is heated at an ambient temperature of 23°C±2°C for 60 min, take a distance of at least 30 mm from the edge of the sample. Measure the peel strength between the EVA film and the glass according to the test method of 5.5.4. Record the EVA film separately. The difference between the peel strength and the yellow index before and after aging of the glass.

6 inspection rules

6.1 factory inspection

6.1.1 General

Products must be manufactured by the manufacturer's quality inspection department in accordance with the provisions of this standard after passing inspection, and attach a product quality certificate, before leaving the factory.

6.1.2 Factory Inspection Items

Appearance, degree of crosslinking and shrinkage.

6.1.3 Factory Inspection Group Approval

Using the same batch of raw materials, the same formula, the same specification of EVA film produced under the same process conditions is an inspection lot, and the film area is used as the unit.

6.1.4 Factory Inspection Sample

The factory inspection is carried out in accordance with the provisions of GB/T 2828.1, and a special inspection level S-3 is adopted. Normally, a sampling plan is checked and the quality of acceptance limit (AQL) is 6.5.

6.2 type inspection

6.2.1 General

In one of the following situations, a type test should be carried out:

a) When the production is resumed after the first production or shutdown;

b) When raw materials or processes change;

c) Once a year under normal production conditions;

d) When a national quality supervision agency or user proposes a type inspection request.

6.2.2 type inspection project

Full project inspection.

6.2.3 type test judgment

The test results meet the requirements of this standard, and the product meets the national environmental requirements for electrical and electronic products, then determine the type of inspection is qualified; if there is a non-conformity, the double sampling test is still not qualified, then determine the type of test Failed.

6.2.4 type test sampling

Type inspection samples are randomly selected from the factory inspection qualified products.

7 Packaging, Signage, Transport and Storage

7.1 Packaging

7.1.1 The product shall be in rolls and shall be packaged in a moisture-proof and dust-proof package for each roll of product.

7.1.2 Each volume of product is accompanied by a certificate of conformity. The item is product type, specification, batch number, and production date.

7.2 logo

Each box of products shall be marked with the factory name, product name, model number, specification, quantity, batch number, production date and execution standard.

7.3 Transportation

Products should be protected from light, heat, and moisture. Avoid beating and stacking in the open air. Do not bend the product or damage the package.

7.4 Storage

7.4.1 Storage location

The product should be stored indoors, with the temperature controlled within a range of 0°C to 30°C and a relative humidity of less than 60 00, avoiding direct light exposure. Do not go near heating equipment and expose it to dusty places.

7.4.2 Storage Method

The storage method is as follows:

a) Before opening the box, check the packaging box of the stored product should be left intact;

b) Once the original packaging box is opened, the product should be used within 48 hours and the unused part is resealed in the original packaging or similar packaging.

7.4.3 Storage time

The product has a shelf life of 6 months from the date of production.

Appendix A

(Normative Appendix)

Hydrolysis and back titration for measuring VA containing discs of EVA film

A.1 Principle

The sample was dissolved in xylene and a solution of potassium hydroxide-ethanol was added to hydrolyze the acetic acid hydrate. An excessive amount of sulfuric acid or hydrochloric acid was added, and phenolphthalein was used as an indicator to titrate the excess acid with a standard solution of alkali.

A.2 Reagents

The required reagents are as follows:

a) xylene;

b) Sulfuric acid solution: 5 g/L (or hydrochloric acid solution: 3.7 g/L);

c) Potassium hydroxide-ethanol solution: Dissolve 5.6 g of solid potassium hydroxide (KOH) in 500 mL of ethanol solution, dilute to 1000 mL with ethanol solution, and let it stand overnight before gently decanting the supernatant;

d) Sodium hydroxide standard titration solution: c (NaOH) = 0.1mol/L;

e) Phenolphthalein indicator: 0.7 g phenolphthalein was dissolved in 100 mL ethanol.

A.3 Sample preparation

The EVA film sample was cut into small particles, the mass of each particle should be less than 0.05g.

A.4 Test procedure

The test process is as follows:

a) Weigh 0.3g of particulate EVA film sample, accurate to 0.0001g, in a dry Erlenmeyer flask;

b) Add 50 mL of xylene to the Erlenmeyer flask and pipette 25 mL of potassium hydroxide-ethanol solution. The conical flask was equipped with a reflux condenser and placed on a heating device, the temperature was maintained at 200 ° C, reflux 2h;

. After the sample was completely hydrolyzed, the flask was removed and allowed to cool to room temperature. Use another pipette to transfer 30 mL of the sulfuric acid or hydrochloric acid solution to the flask. Plug the bottle with a stopper and add a few drops of phenolphthalein indicator after shaking. Titrate with standard titration with sodium hydroxide until the light red color appears.

A.5 Test results

According to formula (A.1), calculate the VA content in the EVA film sample, and take the arithmetic average of the three groups of samples, accurate to 0.1%.