Method for evaluating mobility of auxiliaries in photovoltaic adhesive film

Abstract

The invention belongs to the technical field of photovoltaic packaging adhesive films, and particularly relates to a method for evaluating mobility of an assistant in a photovoltaic adhesive film, which comprises the following steps: S1, sample preparation: fully mixing POE particles and EVA particles with an assistant respectively, standing, then taking the POE particles and the EVA particles for open milling, and tabletting to obtain POE and EVA film samples; wherein the auxiliary agent comprises at least one of a peroxide initiator, an acrylate cross-linking agent and a silane coupling agent; s2, pre-treating: discharging interlayer air from laminated films after tabletting, standing, separating the laminated films, and cutting the middle part into a small-specification sample for later use; s3, extracting and testing, namely weighing a small-specification sample, cutting into fragments, standing by using ethyl acetate as an extracting agent, and testing the content of the auxiliary agent through a liquid chromatograph.

Description

Technical Field

[0001] This invention belongs to the field of photovoltaic encapsulation film technology, specifically relating to a method for evaluating the migration of additives in photovoltaic encapsulation films. Background Technology

[0002] Photovoltaic encapsulation films are used in photovoltaic modules to bond solar cells to glass or backsheets, while also providing sealing, insulation, and protection. Mainstream TOPCon cells are susceptible to corrosion from moisture and acidic substances; therefore, the primary encapsulation films selected are polyolefin elastomer (POE) films and EVA-POE-EVA (EPE) co-extruded films, which offer relatively better moisture barrier properties. EPE co-extruded films are expected to become the mainstream choice for photovoltaic encapsulation materials, with their market share projected to approach 40% by 2025. Because POE is a non-polar molecule, while most additives are polar molecules, additives in the polyolefin (P) layer can easily diffuse and migrate into the elastomer (E) layer during extrusion, storage, and even lamination. This results in a significant reduction in the actual additive content in the P layer compared to the theoretical content, potentially leading to a decrease in the basic performance of the encapsulation film and the reliability of the module.

[0003] CN 117825553A discloses a method for quantitatively evaluating the precipitation of additives in POE films. The steps are as follows: (1) The POE film test sample is rinsed with a mixed solvent to obtain a rinsing solution; the mixed solvent includes a combination of solvents with high solubility parameters and solvents with low solubility parameters; (2) The rinsing solution is subjected to gas chromatography to obtain gas chromatography data, and the gas chromatography data is analyzed to obtain quantitative detection results of additive precipitation in the POE film. This method mainly assesses the precipitation of additives in POE films by rinsing the additives on the surface of the film and testing the content of each additive. However, this method cannot be used to assess the migration and distribution of additives in each layer of co-extruded EPE films.

[0004] Therefore, we need a method to assess the migration of additives in each layer of EPE film. This would allow developers to intuitively and quantitatively determine the true content of additives in each layer, and also enable the screening of low-migration additives and optimization of formulation structures. Currently, however, a simple and intuitive method for assessing additive migration in EPE films is lacking.

[0005] It should be noted that the information disclosed in this background section is only for understanding the background technology of the present application concept, and therefore, the above description is not considered to constitute prior art information. Summary of the Invention

[0006] This disclosure provides at least one method for evaluating the migration of additives in photovoltaic films.

[0007] In a first aspect, embodiments of this disclosure provide a method for evaluating the migration of additives in photovoltaic films, comprising the following steps: S1, sample preparation, thoroughly mixing POE particles and EVA particles with additives and allowing them to stand, then taking POE particles and EVA particles for open mixing and pressing to obtain POE and EVA film samples; wherein, the additives include at least one of peroxide initiators, acrylate crosslinking agents and silane coupling agents; S2, pretreatment, after pressing the film sheets, removing the air between the layers and allowing them to stand, then separating the laminated film sheets and cutting the middle portion into small-sized samples for later use; S3, extraction test, weighing the small-sized samples, cutting them into fragments, using ethyl acetate as the extraction solvent, allowing them to stand, and then testing the additive content using a liquid chromatograph.

[0008] In one optional embodiment, the POE particles include at least one of ethylene-octene copolymer particles and ethylene-butene copolymer particles.

[0009] In one optional embodiment, the EVA particles are ethylene-vinyl acetate copolymer particles.

[0010] In one optional embodiment, the additive includes one or more combinations of diisopropyl peroxide, tert-butyl peroxide-2-ethylhexyl percarbonate, 1,1'-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, benzoyl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, diisopropyl peroxide-2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, trimethylolpropane triacrylate, triallyl isocyanate, pentaerythritol triacrylate, isopropyl methacrylate, vinyltrimethoxysilane, methacryloxysilane, aminopropyltriethoxysilane, vinyltrimethoxysilane prepolymer, and vinyltrimethoxysilane prepolymer.

[0011] In one optional implementation, the settling temperature in step S1 is 50°C, and the settling time is not less than 5 hours.

[0012] In one optional embodiment, the tableting temperature in step S1 is 95-105°C, the tableting time is not less than 60 seconds, and the holding time is not less than 5 seconds.

[0013] In one optional embodiment, the temperature for standing in step S2 is 25–60°C, and the standing time is 12–48 hours.

[0014] In one optional implementation, the size of the small sample is not less than 10cm*10cm.

[0015] In one optional implementation, the size of the fragment is not less than 2mm*2mm.

[0016] In one optional implementation, the settling time in step S3 is not less than 24 hours.

[0017] The beneficial effects of this invention are that, when using the same adhesive particles, the method for evaluating the migration of additives in photovoltaic films can be used to screen additives with low migration and optimize the formulation structure. It can also serve as a reference for the migration of additives in the E and P layers of co-extruded films.

[0018] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained through the structures particularly pointed out in the description and the drawings.

[0019] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 A pre-extraction liquid phase spectrum provided in an embodiment of this disclosure;

[0022] Figure 2 This is a post-extraction liquid phase spectrum provided in an embodiment of the present disclosure. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] As used herein, the phrases “in one embodiment,” “according to one embodiment,” “in some embodiments,” etc., generally refer to the fact that a particular feature, structure, or characteristic following the phrase can be included in at least one embodiment of this disclosure. Therefore, a particular feature, structure, or characteristic can be included in more than one embodiment of this disclosure, such that these phrases do not necessarily refer to the same embodiment. As used herein, the terms “example,” “exemplary,” etc., are used to “serve as an example, instance, or illustration.” Any implementation, aspect, or design described herein as “example” or “exemplary” is not necessarily to be construed as preferred or superior to other implementations, aspects, or designs. Rather, the use of the terms “example,” “exemplary,” etc., is intended to present concepts in a specific manner.

[0025] In this document, exemplary embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. As used herein, expressions such as “at least one of…” modify the entire list of elements when following a list of elements, rather than individual elements in the list. For example, the expression “at least one of a, b, and c” should be understood to include only a, only b, only c, both a and b, both a and c, both b and c, or all of a, b, and c.

[0026] The terminology used herein is for the purpose of describing specific exemplary configurations only and is not intended to be limiting. As used herein, the singular articles “a,” “an,” and “the” may also be intended to include plural forms unless otherwise clearly stated herein. The terms “comprising,” “including,” and “having” are inclusive and thus specify the presence of features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein should not be construed as requiring them to be performed in the specific order discussed or shown, unless specifically identified as such. Additional or alternative steps may be employed.

[0027] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0028] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0029] This disclosure provides a method for evaluating the migration of additives in photovoltaic films, comprising the following steps: S1, sample preparation, POE particles and EVA particles are thoroughly mixed with additives and allowed to stand, then POE particles and EVA particles are taken for open mixing and pressing to obtain POE and EVA film samples; wherein, the additives include at least one of peroxide initiators, acrylate crosslinking agents and silane coupling agents; S2, pretreatment, after the film sheets are pressed and stacked, the air between the layers is removed and allowed to stand, then the stacked film sheets are separated, and the middle part is cut into small-sized samples for later use; S3, extraction test, the small-sized sample is weighed and cut into fragments, ethyl acetate is used as the extraction solvent, and after standing, the additive content is tested by liquid chromatography.

[0030] In some embodiments, specifically, the POE particles include at least one of ethylene-octene copolymer particles and ethylene-butene copolymer particles.

[0031] In some embodiments, specifically, the EVA particles are ethylene-vinyl acetate copolymer particles.

[0032] In some embodiments, the additives specifically include one or more combinations of diisopropyl peroxide, tert-butyl peroxide-2-ethylhexyl percarbonate, 1,1'-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, benzoyl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, diisopropyl peroxide-2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, trimethylolpropane triacrylate, triallyl isocyanate, pentaerythritol triacrylate, isopropyl methacrylate, vinyltrimethoxysilane, methacryloxysilane, aminopropyltriethoxysilane, vinyltrimethoxysilane prepolymer, and vinyltrimethoxysilane prepolymer.

[0033] In some embodiments, specifically, the temperature for standing in step S1 is 50°C, and the standing time is not less than 5 hours.

[0034] In some embodiments, specifically, in step S1, the tableting temperature is 95-105°C, the tableting time is not less than 60 seconds, and the holding time is not less than 5 seconds.

[0035] In some embodiments, specifically, the temperature for standing in step S2 is 25–60°C, and the standing time is 12–48 hours.

[0036] In some embodiments, specifically, the size of the small-sized sample is not less than 10cm*10cm.

[0037] In some embodiments, specifically, the size of the fragment is not less than 2mm*2mm.

[0038] In some embodiments, specifically, the settling time in step S3 is not less than 24 hours.

[0039] Example 1

[0040] Sample preparation stage: 100 parts of POE particles (Dow PV8860) were mixed with 0.65 parts of TBEC, 0.65 parts of TAIC, 0.45 parts of cyclic siloxane, 0.45 parts of silane coupling agent K570, and 0.45 parts of TMPTMA until homogeneous. After standing at 50°C for 5 hours, the mixture was started for refining. 100 parts of EVA particles were then refined separately without any additives. 50g of each of the POE particles and EVA particles (Sirbon V2825) were then compressed into tablets.

[0041] Pretreatment: Stack the compressed POE and EVA films, remove the air between the layers, let stand at 25℃ for 24 hours, separate the stacked films, take the middle part, and cut it into 10*10cm samples for later use.

[0042] Extraction test: Weigh 3g of sample, cut it into 2*2mm fragments, add 18mL of ethyl acetate as the extraction solvent, let stand for 24h, and test the content of auxiliary agent by liquid chromatography.

[0043] Example 2

[0044] Compared with Example 1, this embodiment is the same except for the sample preparation stage.

[0045] Sample preparation stage: Mix 100 parts of POE particles with 0.45 parts of TBEC, 0.45 parts of TAIC, 0.3 parts of cyclic siloxane, 0.3 parts of silane coupling agent K570, and 0.3 parts of TMPTMA until homogeneous. Let stand at 50°C for 5 hours before starting the refining process. Separately, refining 100 parts of EVA particles without any additives. Take 50g of POE particles and 50g of EVA particles respectively for tableting.

[0046] Example 3

[0047] Compared with Example 1, this embodiment is the same except for the sample preparation stage.

[0048] Sample preparation stage: Mix 100 parts of POE particles with 0.25 parts of TBEC, 0.25 parts of TAIC, 0.15 parts of cyclic siloxane, 0.15 parts of silane coupling agent K570, and 0.15 parts of TMPTMA until homogeneous. Let stand at 50°C for 5 hours before starting the refining process. Separately, refining 100 parts of EVA particles without any additives. Take 50g of POE particles and 50g of EVA particles respectively for tableting.

[0049] Example 4

[0050] In Example 2, the POE film after the initial extraction was thoroughly dried, and then extracted again for 24 hours using the same operating procedure. The content of the auxiliary agent was then tested by liquid chromatography.

[0051] Test results:

[0052] Specifically, the initial P-layer additive content is shown in Table 1:

[0053] Table 1

[0054]

[0055] Specifically, the additive content in the P layer and E layer after the film laminations have been left to stand for 24 hours is shown in Table 2:

[0056] Table 2

[0057]

[0058]

[0059] Please see Figure 1 and Figure 2 ,like Figure 1 and Figure 2 As shown, comparing the test results, the initial P-layer additive content in Examples 1-3 shows that the extracted additives are very close to the initial added amount, indicating that the one-step extraction method can fully extract the free additives added inside the film. The reason for the partial difference from the initial added amount is the possible loss during processing, human operation error, and the shift in the liquid phase peak position caused by the reaction of a small amount of additives during processing. Example 4 illustrates that for this system (POE / EVA), the method described in the patent has achieved sufficient extraction of the additives at the stated standing temperature and time. Extending the standing time no longer increases the amount of additives extracted, indicating that the extraction has reached equilibrium.

[0060] Comparing the test results of Examples 1-3, the additive content in the P layer and E layer was determined after 24 hours of stacking. After the POE and EVA films were stacked, the additives in the P layer migrated to the E layer. After migration equilibrium, the additive concentration in the P layer was lower than the initial concentration, while the additive concentration in the E layer was higher than the initial concentration. The method described in this patent can be used to determine the final actual content of additives in the P and E layers of the EPE film.

[0061] Furthermore, the method described in this invention patent can be used to compare the migration capabilities of different additives, thereby screening for additives with better migration resistance.

[0062] In summary, this method for assessing the migration of additives in photovoltaic films, when using the same adhesive particles, can be used to screen additives with low migration and optimize formulation structures. It can also serve as a reference for the migration of additives in the E and P layers of co-extruded films.

[0063] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for evaluating the migration of an additive in a photovoltaic encapsulant, characterized by, Comprising the following steps: S1, sample preparation, respectively mix POE particles and EVA particles with additives, stand, then open mill POE particles and EVA particles, press into tablets, get POE and EVA tablet samples; Wherein, the additives include at least one of peroxide initiators, acrylate crosslinking agents and silane coupling agents; S2, pretreatment, after the tablet is stacked, the air between the layers is discharged and then stand, then separate the stacked tablets, cut the middle part into small size samples for standby; S3, extraction test, weigh the small size samples into pieces, use ethyl acetate as the extractant, stand, then test the additive content by liquid chromatograph.

2. The evaluation method of claim 1, wherein, The POE particles include at least one of ethylene-octene copolymer particles and ethylene-butene copolymer particles.

3. The evaluation method of claim 1, wherein, The EVA particles are ethylene-vinyl acetate copolymer particles.

4. The evaluation method of claim 1, wherein, The additives include one or more of a combination of diisopropyl peroxydicarbonate, tert-butyl peroxy-2-ethylhexyl carbonate, 1,1'-bis(tert-butyl peroxy)-3,3,5-trimethylcyclohexane, benzoyl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, dicumyl peroxide 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, trimethylolpropane triacrylate, triallylisocyanurate, pentaerythritol triacrylate, isopropyl methacrylate, vinyltrimethoxysilane, methacryloyloxysilane, aminopropyltriethoxysilane, vinyltrimethoxysilane prepolymer, and vinyltrimethoxysilane prepolymer.

5. The evaluation method of claim 1, wherein, The standing temperature in step S1 is 50℃, and the standing time is not less than 5h.

6. The evaluation method of claim 1, wherein, The tablet pressing temperature in step S1 is 95-105℃, the tablet pressing time is not less than 60s, and the holding time is not less than 5s.

7. The evaluation method of claim 1, wherein, The standing temperature in step S2 is 25-60℃, and the standing time is 12-48h.

8. The evaluation method of claim 1, wherein, The size of the small size sample is not less than 10cm*10cm.

9. The evaluation method of claim 1, wherein, The size of the pieces is not less than 2mm*2mm.

10. The evaluation method of claim 1, wherein, The standing time in step S3 is not less than 24h.

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