Study on the bonding force of photovoltaic backplate bonding coating and encapsulation film

photovoltaic backpanel sits on the outermost layer of the photovoltaic module and acts as a protection and support for the cellWith the vigorous development of the photovoltaic industry, photovoltaic backpanels, as important packaging materials for components, have been paid more and more attentionThe back plate is mainly composed of 3 layers of structure, from the outside to the inside in turn is the weather ingress, insulation layer, bonding layerIn recent years, the bonding layer of the back plate has been mostly fluorine-carbon coating (fluorocarbon bonding layer/bond coating)Bonding coating and encapsulation film EVA layering in the components feedback from the power station are the main problems of component failure in recent years, the bonding performance of fluorocarbon coating and EVA is the key factor in determining the effect of backplate and EVA packaging, and some component manufacturers have even raised the gluable force standard of fluorocarbon coating and EVA from the original 40N/cm to 60N/cmDetermining the factors that affect the bonding force of the backplate bonding coating and EVA, and making effective use of the adhesive force between the coating and EVA, has become an important subject for many backplate manufacturersbecause the fluorocarbon coating and EVA film will affect the bonding force, so this paper from the EVA film and fluorocarbon coating formulation of these two aspects, the factors affecting the coating and EVA adhesion force, for the preparation and EVA film bonding force excellent fluorocarbon coating to provide a useful reference1 experimental1.1 experimental raw materialsfluorocarbon resins: trifluoroethylene-vinyl ether copolymer, Changxing Chemical Co., Ltd.; acrylic resin: Deqian Chemical; titanium dioxide: DuPont; anti-light powder: 5 m, Degusay; anion dispersant agent: Bik chemical; acrylic gator: evononic; curing HDI triglist: CosyEVA film A: transparent, universal, a domestic company provides; EVA film B: transparent, anti-snail grain, a domestic company provides; EVA film C: transparent, with anti-PID function, a domestic company provides; film A, film B, film C placed for a period of time spare1.2 coating and coating sample preparationwill be fluorocarbon resin, acrylic resin, solvent, dispersant, titanium dioxide in a certain proportion added to the beaker, dispersed uniformly, import edgout grinding machine, control the fineness of the coating after 5 m, get the pre-mix of fluorocarbon coating, and then add a certain amount of anti-carbon powder, concentrate in the premix to the secondary dispersion, dispersant coatingwill be fluorocarbon coating, curing agent, solvent in a certain proportion into the beaker, mixed evenly after the back plate bonding layer with fluorocarbon coating, the coating with a silk rod coated on the corona after the polyphenyl glycol (PET) substrate, dry, cooked to get the sun back plate with the bonding layer1.3 performance test
the bonding force of the backplate and EVA is tested in accordance with the requirements of GB/T2790-1995The crosslinking of EVA film is tested according to the extraction method 2 results and discussion
2.1EVA film on the coating and EVA bonding force EVA film is an important packaging material for battery components, with the recent years more and more functional requirements for EVA film, in addition to the conventional film A, there is also anti-snail grain film B, anti-PID function of the film C, so this paper on the three kinds of packaging film research 2.1.1 THE EFFECT OF THE TYPE OF
EVA FILM ON THE COATING AND EVA ADIS
AT DIFFERENT LAMINATION TIMES, THE BONDING FORCE OF THE 3 KINDS OF FILM AND COATING IS SHOWN IN FIGURE 1 Figure 1 The change of 3 kinds of adhesive force of different laminates is visible from Figure 1, in different laminate time, 3 kinds of film and coating bonding force are showing the trend of increasing and then decreasing, the best lamination time of 3 kinds of film is 11min, and under this condition, A, B film and coating bonding force is better than C different laminate time, the cross-linking degree of the three types of film sits is shown in Figure 2 Figure 2 Changes in the crosslinking degree of 3 different laminates by Figure 2, in laminate 7min, the crosslinking degree of the film C is higher than that of A and B, the time is extended to 11min, the reaction rate of the film A and B increases rapidly, the crosslinking degree exceeds the cross-linking degree C cross-linking degree, the trend of this change corresponds to the adhesive force of the film and the coating, that is, the greater the cross-linking degree, the greater the bonding force of the film and the coating, so in the best lamination time of 11min, the adhesive force of the film A, B and the coating is better than C 2.1.2 EVA film placement of different time on the effect of the coating and EVA bonding force
in the case of poor sealing, after a period of time, the coating and EVA film bonding force as shown in Figure 3 Figure 3 the effect of the glue time on the coating and the adhesive force of the film visible from Figure 3, with the extension of the EVA film placement time, 3 kinds of EVA film and coating bonding force are showing a downward trend of shock Because the bonding performance of the adhesive film A and B is quite and better than C, this paper uses the vulcanization curve of the adhesive film A to study the effect of EVA film placement on the coating and EVA bonding force at different times, and analyzes the reasons for the attenuation of the adhesive force of the adhesive film The vulcanization curve of the film is shown in Figure 4 Figure 4 the vulcanization curve of the old and new film is
visible from Figure 4, with the extension of the placement time, the maximum torque of the film is getting smaller and smaller, the maximum torque change of the film for 6 months is not much, but after 9 months of placement, the torque of the film is significantly reduced, that is, the degree of cross-linking of the old film significantly decreased, so the adhesive force of the coating and EVA decreased after a period of time Newly purchased film, if not tightly stored should be used up within 6 months 2.2 Coating Formulation's Effect on Coating and EVA Bonding Force
Coating Formulation mainly contains resin and face fillers, and differences in composition and content affect the bonding force of the coating and EVA 2.2.1 the quality ratio of fluorocarbon and acrylic resin on the effect of coating and EVA bonding force
bonding coating contains fluorocarbon resin, but the surface of fluorocarbon resin can be low, in order to improve the coating and EVA bonding performance, often add acrylic resin to modify The effect of the quality ratio of fluorocarbon resin sin on the coating and EVA bonding force is shown in Figure 5 Figure 5 resin quality ratio on the coating and EVA bonding force
can be seen by Figure 5, with the increase in acrylic resin addition ratio, the coating and EVA film bonding force gradually increased, mainly because acrylic resin contains good adhesion with EVA polar group, when the acrylic content increases, the number of polar groups in the coating increases, thus increasing the coating and EVA bonding force However, as the proportion of acrylic resin increases to 1:2, the increase in bonding force slows down, in addition, as the increase of acrylic resin, the weather resistance of the coating will decrease Therefore, it is appropriate to choose the quality ratio of fluorocarbon sofe and acrylic to be 1:1 2.2.2 Effects of the type and content of the extinction powder on the coating and EVA adhesion fluorocarbon coatings often add a decarbon powder to adjust the gloss of the coating, but the existing defrost powder has surface treatment and unsurface treatment, in order to improve the adhesive force of the coating and EVA, the effect of these 2 kinds of extinction powder dosage on the coating and EVA bonding force, the results are shown in Figure 6 Figure 6 The effect of the extinction powder on the coating and EVA bonding force
can be seen by Figure 6, with the increase of the content of the de-light powder, the coating and EVA bonding force are reduced, compared with 2 kinds of defrost powder, the surface-treated defrost powder preparation of the coating and EVA bonding force is reduced faster, because the surface-treated defrost surface has polyethylene wax, the substance will be in the lamination and the formation of a weak interface In order to ensure the bonding force of the coating and EVA, the surface untreated light-reformer should be selected, and the content of the decarbonized powder should be less than 3% 2.3 Effect of coating thickness on coating and EVA adhesion the thickness of the fluorocarbon coating on the coating and EVA adhesion are shown in Figure 7 Figure 7 The effect of the coating thickness on the bonding force of the coating and EVA visible from Figure 7, the thicker the thickness of the coating, the greater the bonding force of the coating and EVA, and the increase in the adhesion of the coating and EVA when the thickness of the coating is greater than 6.5 m The coating surface profile of different thicknesses is shown in Figure 8 Figure 8 the surface of the coating of different thicknesses
as can be seen from Figure 8, the thicker the coating, the less exposed inorganic particles Therefore, the more the adhesive resin in the coating and EVA contact, the greater the bonding force of the coating and EVA, when the thickness of the coating increased to 6.5 m, greater than the particle size of the defrost powder 5 m, the contact area of the resin and EVA in the coating tends to saturate, and then continue to increase the thickness of the coating, the more the adhesive force of the coating and EVA increases slowly Taking into account the effect of the particle size of the yan filler, the thickness of the coating is preferably 6.5 to 7.5 m 3 knot (1) 3 kinds of film (universal A, anti-PID function B, anti-snail pattern function C) and the same coating after the cross-linking degree is different, resulting in different bonding force, the adhesive effect of the film A and B bonding is equivalent, are better than the film C (2) the film in the process of placement will reduce the coating and the adhesive force of the film, in this experiment, the film seal bad storage, should be used up within 6 months (3) paint selection of fluorine carbon and acrylic 2 kinds of resin mix, acrylic content increased, will increase the coating and EVA bonding force, fluorine carbon and acrylic quality ratio of 1:1, the adhesion force value tends to stabilize (4) paint to add anti-light powder, it is best to use silicon dioxide without organic wax surface treatment, and its content should be less than 3% (5) the thickness of the coating should be larger than the particle size of the face filler in the coating, if the particle size of the face filler is 5 m, the thickness of the preferred coating is 6.5 to 7.5 m