CN101240157A - Ethylene-vinyl acetate copolymer adhesive film for packaging solar energy battery and preparation method thereof - Google Patents

Abstract

The invention discloses an ethylene-vinyl acetate copolymer adhesive film for solar cell packaging and a preparation method thereof. The adhesive film is made of ethylene-vinyl acetate copolymer particles, curing agent, thermally conductive filler, antioxidant, ultraviolet light stabilizer, and coupling agent in a certain proportion by mass; Filler and coupling agent are mixed, dried, and ground and dispersed to obtain active thermally conductive filler; ② Mix ethylene-vinyl acetate copolymer particles with curing agent; ③ Mix antioxidant and ultraviolet light stabilizer with the above-mentioned active thermally conductive filler; ④ The mixture of the above step ③ is added to the mixture of step ②, blended and extruded, and the extruded product is cast, cooled, drawn, and coiled to obtain the film of the present invention. It has the characteristics of high thermal conductivity, which is more than three times higher than that of existing products, improves the photoelectric conversion rate of solar cells, and prolongs the service life.

Description

Ethylene-vinyl acetate copolymer adhesive film for solar cell encapsulation and preparation method thereof

1. Technical field

The invention relates to a polymer encapsulation material for solar cells, in particular to an ethylene-vinyl acetate copolymer (EVA) adhesive film used for encapsulation of solar cells and a preparation method thereof.

2. Background technology

Solar cells are packaged with silicon wafers by means of two layers of polymer packaging films, and then bonded with upper and lower protective layer materials glass, TPT film or aluminum alloy plate. First of all, the encapsulation material must be transparent, and the transmittance must be high, so as to ensure that the encapsulated solar cell module has sufficient photoelectric conversion efficiency; in addition, the encapsulation material must have strong adhesive force, so that it can be better fixed and Protect the solar cells; the packaging material is thermosetting to ensure reliable operation of solar modules at high temperatures. Before the 1980s, liquid silicone resin and polyvinyl butyral resin sheets (PVB) were tried at home and abroad, but they were all eliminated due to high prices and harsh construction conditions. Beginning in the 1980s, American Jet Propulsion and Springbom laboratories, the National Renewable Energy Laboratory (NREL), etc., based on the light transmittance, modulus, processability, price, etc. of the material, ethylene-vinyl acetate copolymer (EVA) and ethylene-methyl methacrylate (EMMA) are included in the research plan, and the EVA film is easy to turn yellow under harsh weather conditions, thereby affecting the shortcoming of the photoelectric conversion rate of solar cells (A.W.Czanderna*, F.J.Pern, Encapsulation of PV modules using ethylene vinyl acetate copolymer as a pottantA critical review, Solar Energy Materials and Solar Cells 43(1996) 101-181.); In order to improve the yellowing phenomenon of EVA film, you can adjust the UV light stabilizer in the formula, Antioxidants, cross-linking curing agents and other varieties and proportions to improve the aging resistance of EVA film (application number 200510034750, South China University of Technology, EVA film for aging-resistant solar cell packaging and preparation method thereof).

In deserts or plateau areas rich in solar energy resources, solar cell components have to bear more solar radiation, and the heat accumulated on the silicon cell is more, if it is not dissipated in time, it will lead to a decrease in the photoelectric conversion rate of the silicon cell. , The yellowing problem of EVA film will also be very prominent, affecting its light transmittance, which greatly restricts the application of solar cell modules in these areas. In addition, with people's attention to environmental protection issues in solar cell production and the shortage of silicon cell resources, people have put forward higher requirements on the service life of solar cell components. However, in the literature published abroad at present, there are few studies on the thermal conductivity of EVA film, and no literature reports have been seen yet.

3. Contents of the invention

(1) Purpose of the invention:

The purpose of the present invention is to aim at the deficiency of the weather resistance of the EVA adhesive film used in the solar cell in the prior art, emphatically improve the thermal conductivity coefficient of the existing EVA adhesive film, provide a kind of heat-resistant oxygen, anti-ultraviolet light aging resistance, high heat good solar energy The invention discloses an EVA adhesive film for battery packaging, and provides a preparation method of the adhesive film.

(2) Technical solutions for realizing the purpose of the invention

The principle of the invention: take EVA (ethylene-vinyl acetate copolymer) as the matrix, adopt suitable antioxidant, ultraviolet light stabilizer, curing agent, and select high thermal conductivity inorganic filler and/or coupling agent, adopt mechanical extrusion calendering The way of molding makes EVA film with uniform dispersion and good thermal conductivity.

An ethylene-vinyl acetate copolymer adhesive film for solar cell encapsulation is characterized in that it is an ethylene-vinyl acetate copolymer containing a thermally conductive filler, and is made of the following materials in proportions by weight:

100 parts of ethylene-vinyl acetate copolymer pellets, 0.5-2.0 parts of cross-linking curing agent, 30-200 parts of thermally conductive filler, 0.1-1.0 parts of antioxidant, 0.1-1.0 parts of ultraviolet light stabilizer, and 0-4.0 parts of coupling agent.

The preparation method of ethylene-vinyl acetate copolymer (EVA) adhesive film for solar cell encapsulation is as follows

(1) Mix 30-200 parts of thermally conductive filler with 0-4.0 parts of coupling agent, dry, grind and disperse to obtain active thermally conductive filler;

(2) Mix 100 parts of EVA pellets and 0.5-2.0 parts of cross-linking curing agent evenly;

(3), mix 0.1-1.0 part of antioxidant, 0.1-1.0 part of ultraviolet light stabilizer and the active thermally conductive filler prepared in step (1), and mix evenly;

(4) Add the mixture of the above step (3) to the mixture of step (2), and after mixing evenly, carry out blending and extrusion, the temperature is controlled at 80-105°C, and the extrudate is cast, cooled, Traction, coiling operation, obtain the solar cell encapsulation EVA adhesive film of the present invention;

One molecule of EVA in the above-mentioned EVA pellets contains a segmented vinyl group: vinyl acetate group (mass ratio)=2:1;

The above-mentioned crosslinking curing agent is a peroxide, such as 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane;

The above-mentioned antioxidants are hindered phenols, such as n-octadecyl p-(4-hydroxy-3,5-di-tert-butylphenyl) propionate; or phosphites, such as triphosphite (2,4-Di-tert-butylphenyl) ester;

The above-mentioned UV stabilizers are hindered amines, such as bis(2,2,6,6-tetramethyl-4-piperidine) sebacate;

The above-mentioned thermally conductive filler is one of aluminum oxide, magnesium oxide, BeO, AlN or SiC as an inorganic thermally conductive filler, and its particle size is 10nm-1μm;

The above-mentioned coupling agents are silane series coupling agents or titanate coupling agents.

In the present invention, under the condition of ensuring that the EVA adhesive film is fully bonded to glass, TPT or aluminum alloy plates, a formula that can greatly improve the thermal conductivity of the EVA packaging adhesive is selected and compounded to obtain not only good thermal oxygen resistance and ultraviolet light resistance, but also a EVA film with good thermal conductivity, the thermal conductivity of EVA film can be increased by about 3 times compared with the existing film.

Compared with the prior art, the inventive method has the following advantages:

(1) The thermal conductivity of the existing EVA adhesive film (such as FIRST ^™ EVA solar cell adhesive film) is about 0.32W/m K, and the thermal conductivity of the EVA adhesive film of the present invention: more than 0.5-1.0W/m K . The thermal conductivity can be increased by more than 3 times.

(2) The thermal conductivity of the EVA adhesive film of the present invention is improved, the heat on the silicon cell can be preferably dispersed, the photoelectric conversion rate of the solar cell is improved, the resource of monocrystalline silicon or polycrystalline silicon is saved, the use cost of the solar cell is reduced, and the performance-price ratio is relatively high. high.

(3) The thermal oxygen resistance and ultraviolet light aging resistance are better than the EVA film for existing solar cells, which can improve the service life of existing solar cells;

(4) The EVA adhesive film of the present invention can not only meet the adhesion requirements of EVA and glass, TPT or aluminum alloy plate, but also has higher thermal conductivity than the existing EVA adhesive film, and can be used for concentrated photovoltaic power generation systems and Solar power applications in remote areas.

Detailed ways

Example 1

In terms of mass parts, 30 parts of 0.7 μm 0.5 μm alumina and 1.6 parts of titanate coupling agent (such as NDZ311) were thoroughly mixed, dried at 80 ° C, ground and dispersed, and then added to 1.3 parts of 2,5- Dimethyl-2,5-bis(tert-butyl peroxy)hexane curing agent and 100 parts of EVA pellets are mixed uniformly in the mixture; then 0.25 parts of p-(4-hydroxyl-3,5 di-tert Butylphenyl) n-octadecanyl propionate is used as an antioxidant, and 0.3 parts of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate UV light stabilizer is added to the above mixture, and mix well. Pour the mixture into the extruder for blending and extrusion. The temperature is controlled at 100°C. After the extrusion is cast, cooled, drawn, and coiled, the EVA glue with a thermal conductivity of about 0.68W/m·K can be obtained. membrane.

Example 2

In terms of mass parts, 100 parts of alumina with an average particle size of 0.7 μm and 2.0 parts of silane coupling agent (such as Al51) are fully mixed, dried at 80 ° C, ground and dispersed, and then added to 1.3 parts of 2,5-di Methyl-2,5-bis(tert-butyl peroxy)hexane curing agent and 100 parts of EVA pellets are mixed uniformly in the mixture; then 0.25 parts of antioxidant phosphite tris(2,4-di tert-butylphenyl) ester, 0.3 part of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate UV light stabilizer was added to the above mixture, and mixed uniformly, the mixture was co- Mixed extrusion, the temperature is controlled at 105°C, and the extruded product is cast, cooled, drawn, and coiled to obtain an EVA film with a thermal conductivity of about 0.94W/m·K.

Example 3

In terms of parts by mass, 80 parts of alumina with an average particle diameter of 1.0 μm are added to 1.3 parts of 2,5-dimethyl-2,5-bis(tert-butyl peroxy)hexane curing agent and 100 parts of EVA In the mixture after mixing uniformly in the pellets; then 0.25 parts of p-(4-hydroxy-3,5 di-tert-butylphenyl) n-octadecyl propionate as antioxidant, 0.3 parts of UV stabilizer Bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate was added to the above mixture and mixed well. Pour the mixture into the extruder for blending and extrusion. The temperature is controlled at 100°C. After the extrusion is cast, cooled, drawn, and coiled, the EVA glue with a thermal conductivity of about 0.63W/m·K can be obtained. membrane.

Example 4

In terms of parts by mass, 80 parts of aluminum nitride or beryllium oxide with an average particle size of 80nm and 1.6 parts of silane coupling agent (such as Al51) are thoroughly mixed, dried at 80°C, ground and dispersed, then added to 1.3 parts of 2, 5-Dimethyl-2,5-bis(tert-butyl peroxy)hexane curing agent and 100 parts of EVA pellets are mixed uniformly in the mixture; then 0.25 parts of p-(4-hydroxyl-3,5 Di-tert-butylphenyl) n-octadecyl propionate as antioxidant, 0.3 parts of UV stabilizer bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate Add the above mixture and mix well. Pour the mixture into the extruder for blending and extrusion, the temperature is controlled at 100°C, and the extruded product is cast, cooled, drawn, and coiled to obtain an EVA film with a thermal conductivity greater than 1.0W/m·K .

Example 5

In terms of mass parts, 80 parts of magnesium oxide with an average particle size of 100nm and 3.2 parts of titanate coupling agent (such as NDZ201) were thoroughly mixed, dried at 80°C, ground and dispersed, then added to 1.3 parts of 2,5- Dimethyl-2,5-bis(tert-butyl peroxy)hexane curing agent and 100 parts of EVA pellets are mixed uniformly in the mixture; then 0.25 parts of p-(4-hydroxyl-3,5 di-tert Butylphenyl) n-octadecanyl propionate was used as an antioxidant, and 0.3 parts of UV light stabilizer bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate was added to the above mixture, and mix well. Pour the mixture into the extruder for blending and extrusion, the temperature is controlled at 100°C, and the extruded product is cast, cooled, drawn, and coiled to obtain an EVA film with a thermal conductivity of about 0.58W/m·K .

Example 6

In terms of parts by mass, 80 parts of alumina with an average particle size of 20nm and 2.4 parts of titanate coupling agent (such as NDZ201) were thoroughly mixed, dried at 80°C, ground and dispersed, then added to 1.3 parts of 2,5- Dimethyl-2,5-bis(tert-butyl peroxy)hexane curing agent and 100 parts of EVA pellets are mixed uniformly in the mixture; then 0.25 parts of p-(4-hydroxyl-3,5 di-tert Butylphenyl) n-octadecanyl propionate was used as an antioxidant, and 0.3 parts of UV light stabilizer bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate was added to the above mixture, and mix well. Pour the mixture into the extruder for blending and extrusion. The temperature is controlled at 100°C. After the extrusion is cast, cooled, drawn, and coiled, the EVA glue with a thermal conductivity of about 0.67W/m·K can be obtained. membrane.

Claims (8)

1. An ethylene-vinyl acetate copolymer adhesive film for solar cell encapsulation, characterized in that it is an ethylene-vinyl acetate copolymer containing a thermally conductive filler, and is made of the following materials in proportions by weight: 100 parts of ethylene-vinyl acetate copolymer pellets, 0.5-2.0 parts of cross-linking curing agent, 30-200 parts of thermally conductive filler, 0.1-1.0 parts of antioxidant, 0.1-1.0 parts of ultraviolet light stabilizer, and 0-4.0 parts of coupling agent. 2. A method for preparing the film according to claim 1, the preparation steps of which are as follows: (1) Mix 30-200 parts of thermally conductive filler with 0-4.0 parts of coupling agent, dry, grind and disperse to obtain active thermally conductive filler; (2), 100 parts of ethylene-vinyl acetate copolymer pellets are mixed evenly with 0.5-2.0 parts of crosslinking curing agent; (3), 0.1-1.0 part of antioxidant, 0.1-1.0 part of ultraviolet light stabilizer and the active heat-conducting filler prepared in the above step (1) are mixed evenly; (4) Add the mixture of the above step (3) to the mixture of step (2), and after mixing evenly, carry out blending and extrusion, the temperature is controlled at 80-105°C, and the extrudate is cast, cooled, Traction and coiling process to obtain the ethylene-vinyl acetate copolymer adhesive film of the present invention. 3. The preparation method according to claim 2, characterized in that the thermally conductive filler described in step (1) is one of aluminum oxide, magnesium oxide, BeO, AlN or SiC as an inorganic thermally conductive filler, and its particle size It is 10nm-1μm. 4. The preparation method according to claim 2, characterized in that the coupling agent described in step (1) is a silane series coupling agent or a titanate coupling agent. 5. The preparation method according to claim 2, characterized in that 1 molecule of ethylene-vinyl acetate copolymer in the ethylene-vinyl acetate copolymer pellets described in step (2) contains segmented vinyl and vinyl acetate The mass ratio of ester groups is 2:1. 6. The method according to claim (2), characterized in that the cross-linking curing agent described in step (2) is peroxide-based 2,5-dimethyl-2,5-bis(tert butylperoxy) hexane. 7. The method according to claim (2), characterized in that the antioxidant described in step (3) is p-(4-hydroxyl-3,5-di-tert-butylphenyl)propane Acid n-octadecyl ester. 8. The method according to claim (2), characterized in that the ultraviolet light stabilizer described in step (3) is bis(2,2,6,6-tetramethyl-4- piperidinyl) sebacate.