Novel composite functional master batch as well as preparation method and application thereof

Abstract

The invention discloses a novel composite functional master batch, a preparation method and application thereof, and the novel composite functional master batch comprises the following components by mass percentage: 75-85% of EVA resin; 9.1 to 20% of an acid absorbing auxiliary agent; 0.1 to 3% of an anti-PID auxiliary agent; 0.1 to 2% of an anti-aging auxiliary agent; and 0.005 to 1% of a silane coupling agent. The novel composite functional master batch can significantly improve the PCT aging stripping force of a photovoltaic packaging adhesive film, a silane coupling agent is used for premixing an acid absorption auxiliary agent, an anti-PID auxiliary agent and an anti-aging auxiliary agent, granulation is carried out through a double-screw extruder, and the master batch is added into an existing EVA adhesive film formula to be extruded and cast into a film.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic film packaging, in particular to a novel composite functional masterbatch, a preparation method and application thereof. Background Art

[0002] The main problems of photovoltaic EVA film technology at this stage are as follows:

[0003] 1. The long-term reliability of photovoltaic modules is highly dependent on the weather resistance of the encapsulant film. The encapsulant film must maintain its bonding strength with the glass, cells, and backsheet in high-temperature and high-humidity environments (e.g., PCT test conditions: 121°C, 100% RH, 48 hours) to prevent delamination, bubbles, and other factors that can cause significant module power degradation.

[0004] 2. EVA film is easily hydrolyzed in a hot and humid environment to produce acetic acid, which will corrode the battery grid and release sodium ions in the glass in contact with it, causing potential induced degradation (PID) of photovoltaic modules. At the same time, the acidic environment causes the adhesion between the film and the glass, battery or backplane to deteriorate sharply, accelerating delamination and water ingress and corrosion at the edge of the module.

[0005] 3. The cross-linking agents, UV stabilizers, antioxidants and other additives in photovoltaic encapsulation films are easy to migrate to the interface, causing film slippage, local uneven cross-linking, adhesion degradation, film delamination and other reliability problems.

[0006] The current anti-acidification, anti-PID and anti-oxidation technical solutions for photovoltaic EVA films are as follows:

[0007] 1. Neutralize the acetic acid decomposed by EVA by adding acid-absorbing additives (such as alkaline compounds). This type of additive includes traditional inorganic alkaline compounds such as magnesium oxide, magnesium hydroxide, calcium carbonate, and calcium hydroxide. These inorganic powder additives are pre-granulated and dispersed with EVA resin, and then added to the EVA film formulation as functional masterbatch. They are widely used as acid-absorbing additives. However, these inorganic powders have large particle sizes and are prone to agglomeration during masterbatch processing. They are unevenly dispersed in the film and have insufficient contact with acetic acid. The acid-absorbing effect is affected by factors such as the additive particle size, agglomeration, and uneven dispersion, making it unstable. As a result, the film's performance, especially the adhesion after wet-heat aging, is unstable.

[0008] To improve EVA film's resistance to PID, chelating agents such as zirconium hydrogen phosphate are often added to the formulation. Zirconium hydrogen phosphate absorbs free sodium ions in the system through ion exchange, releasing hydrogen ions simultaneously. These inorganic powder additives are also pre-mixed with EVA resin, extruded and granulated, and then added to the film formulation to enhance powder dispersion. However, granulation of zirconium hydrogen phosphate alone is prone to agglomeration, potentially negatively impacting the film's mechanical properties, light transmittance, crosslinking characteristics, bond strength, and long-term weatherability.

[0009] 3. To improve the film's aging resistance, especially its thermal-oxidative aging resistance, additives such as oxidants and light stabilizers are added to the film formula. These additives are typically mixed with EVA resin, extruded, and pelletized before being added to the film formula to increase their dispersion. However, the different additive particles need to be redispersed during film melt extrusion. This can lead to phase separation or agglomeration due to differences in surface energy polarity, resulting in imbalanced additive concentrations in certain areas of the film. Furthermore, the large variations in particle size, density, and melting rate of different additive masterbatches can lead to stratification or fluctuating feedstock during extrusion, affecting product consistency. Summary of the Invention

[0010] In order to solve the above problems existing in the prior art, the present invention provides a novel composite functional masterbatch, a preparation method and application thereof.

[0011] In order to solve the above-mentioned technical problems, the present invention adopts the following solutions:

[0012] In a first aspect, a technical solution of the present invention is to provide a novel composite functional masterbatch, which comprises the following components in terms of mass percentage:

[0013] EVA resin, 75-85%;

[0014] Acid absorption aid, 9.1-20%;

[0015] Anti-PID additive, 0.1-3%;

[0016] Anti-aging additives, 0.1-2%;

[0017] Silane coupling agent, 0.005-1%.

[0018] Furthermore, the acid absorption auxiliary agent comprises, by weight percentage, 9-15% of magnesium hydroxide and 0.1-5% of magnesium oxide.

[0019] Furthermore, the anti-PID additive is zirconium hydrogen phosphate.

[0020] Furthermore, the anti-aging aid is antioxidant 1076.

[0021] Furthermore, the silane coupling agent is KH570.

[0022] Furthermore, the particle sizes of magnesium hydroxide, magnesium oxide and zirconium hydrogen phosphate are all greater than 20 μm.

[0023] Furthermore, the particle sizes of magnesium hydroxide, magnesium oxide and zirconium hydrogen phosphate are all less than 6 μm.

[0024] In a second aspect, a technical solution of the present invention is to provide a method for preparing the novel composite functional masterbatch, the preparation method comprising the following steps:

[0025] The acid-absorbing auxiliary agent is pre-surface coated by a dry high-speed mixing coating process;

[0026] Premixing the acid-absorbing auxiliary agent powder that has been subjected to a surface coating process with an anti-PID auxiliary agent, an anti-aging auxiliary agent, and a silane coupling agent to obtain a premix;

[0027] The EVA resin is mixed with the above premix, added into a twin-screw extruder, melt-blended, extruded and granulated to obtain the novel composite functional masterbatch.

[0028] In a third aspect, a technical solution of the present invention is to provide an application of the novel composite functional masterbatch for preparing photovoltaic encapsulation film.

[0029] Beneficial effects:

[0030] Compared to films containing three single-functional masterbatches, the adhesive film of this invention, with the same additive formulation, exhibits significantly improved adhesion after wet-heat aging, while maintaining similar performance in terms of PID resistance and thermal oxidative aging resistance. This solution significantly reduces processing costs, offering significant economic benefits, while also significantly improving film performance and component reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of the principle of the present invention for improving the peeling force of PCT after aging based on the composite functional masterbatch;

[0032] Figure 2 Schematic diagram of the PCT aging test sample structure according to one embodiment of the present invention. DETAILED DESCRIPTION

[0033] The present invention will be further described below with reference to the accompanying drawings and examples.

[0034] To reduce pelletizing costs, the inventors attempted to combine an acid-absorbing agent, an anti-PID agent, an anti-aging agent, and a silane coupling agent in a specific formula ratio. The mixture was then melt-blended with EVA resin in a twin-screw extruder and extruded into pellets. The original intention was to combine the three functional masterbatches into a single composite masterbatch to reduce masterbatch processing costs. However, in actual application, the inventors unexpectedly discovered that the composite functional masterbatch could improve the peel strength of the EVA encapsulation film PCT after aging, compared to the three single-functional masterbatches. The inventors analyzed and verified this finding, and through repeated experiments, they found the optimal composite functional masterbatch ratio, which significantly improved the peel strength of the EVA encapsulation film PCT after aging.

[0035] The inventors tested the granulation ratios of magnesium hydroxide, magnesium oxide, antioxidant 1076, zirconium hydrogen phosphate, and KH570. At the same time, they also tested the comparison of granulation types. For example, magnesium oxide, magnesium hydroxide, etc. were not added during granulation. The mixture was stirred and mixed with EVA resin in a mixing kettle. The mixture was added to a twin-screw extruder, melt-blended, and extruded into granules. The granulated composite functional masterbatch was melt-extruded through a twin-screw extruder and cast into a film at a casting temperature of 65-78°C. The obtained photovoltaic encapsulation film 1 was vacuum laminated with glass 2 and backboard 3 to obtain a PCT test sample. Figure 2 As shown in the figure, the yellowing value and peel strength of the samples after aging were tested at 121°C and 100% high humidity for 48 hours. After repeated verification and optimization, a composite granulation masterbatch solution for optimizing the peeling strength of PCT after aging was proposed:

[0036] A novel composite functional masterbatch contains EVA resin, magnesium hydroxide (particle size >20 μm, preferably <6 μm) and magnesium oxide (particle size >20 μm, preferably <6 μm) that have been treated by a coating process (according to existing technology, the coating process can achieve uniform and stable organic modification of the powder surface, improving its dispersibility and uniformity in the film), zirconium hydrogen phosphate (particle size >20 μm, preferably <6 μm), antioxidant 1076, and silane coupling agent KH570 accounting for 0.005% to 1% of inorganic powder.

[0037] The inventors speculate that the composite functional masterbatch improves PCT peel strength after aging due to the inherent anti-aging properties of the various additives. Furthermore, the silane coupling agent KH570 is used to pre-mix the various powder additives before pelletizing the composite functional masterbatch, allowing the various powders to be dispersed before pelletization. Granulation through a twin-screw extruder ensures uniform dispersion of the additives. Furthermore, compared to separate pelletization, the inorganic particles are far apart after being dispersed in the film. In composite pelletization, the inorganic particles are fully in contact with each other, creating a synergistic interfacial effect that maximizes the anti-aging properties of the various inorganic compounds. This composite functional masterbatch, through its four-dimensional protection system of "flame retardant - antioxidant - ion lock - interfacial bond," provides core material support for the high-reliability system of photovoltaic modules.

[0038] like Figure 1 As shown, the role of composite functional masterbatch in film:

[0039] The inorganic powder is added to a blending device with a spray device, the silane coupling agent and ethanol are mixed, and the pH value is adjusted to 4 with acetic acid to obtain a silane coupling agent mixed liquid. The above-obtained silane coupling agent mixed liquid is spray-dried and mixed at a mass ratio of 1% to obtain an inorganic functional masterbatch coated with a silane coupling agent. The obtained inorganic functional masterbatch is blended with antioxidant 1076 to obtain a multifunctional inorganic functional masterbatch.

[0040] 1. Interaction mechanism during processing

[0041] During the masterbatch melt granulation process, the silane coupling agent first forms a covalent coating layer on the surface of magnesium hydroxide (MH), magnesium oxide (MgO) and zirconium hydrogen phosphate (ZHP) particles through the orientation of molecular chain segments. This coating effect is achieved through the following mechanism:

[0042] Chemical anchoring: The alkoxy group (-OCH3) of the silane coupling agent reacts with the hydroxyl group (-OH) on the surface of the inorganic particles to form a Si-OM (M = Mg, Zr) covalent bond;

[0043] Steric hindrance effect: The organic long chain segments of the silane coupling agent molecules extend outward to form a three-dimensional barrier on the particle surface, effectively preventing particle agglomeration.

[0044] Improved interfacial compatibility: The organic functional groups undergo entanglement or chemical reaction with the matrix resin molecular chains, allowing the inorganic particles to be evenly dispersed in the molten matrix. Antioxidant 1076 is evenly distributed in the matrix continuous phase through molecular diffusion. Its hindered phenol structure can form weak hydrogen bond interactions with the organic chain segments of the silane coupling agent, further promoting system compatibility.

[0045] 2. Multi-component coordination mechanism network

[0046] Interface chemical bonding system (silane coupling agent)

[0047] Silane coupling agents build a double bonding network at the inorganic particle-matrix interface:

[0048] (1) Lateral bonding: Silane molecules on the surfaces of adjacent particles form a three-dimensional network structure through Si-O-Si crosslinking, which improves the mechanical strength of the interface layer.

[0049] (2) Longitudinal bonding: The organic functional groups of the silane coupling agent undergo grafting reaction with the molecular chains of the matrix resin to form chemical crosslinking points, combining the dispersed phase and the continuous phase into a whole.

[0050] This interfacial bonding enables the stress of the adhesive film to be effectively transferred through the interface layer when subjected to external force, avoiding interfacial peeling caused by stress concentration, thereby improving the adhesion with the glass / back panel.

[0051] Ion migration inhibition system (zirconium hydrogen phosphate)

[0052] Zirconium hydrogen phosphate (ZHP) builds an ion capture network through a layered structure and ion exchange mechanism:

[0053] (1) Physical adsorption: The ZHP interlayer channels have the selective adsorption capacity for migrating ions such as Na+ and K+, and the adsorption capacity can reach 0.8-1.2mmol / g.

[0054] (2) Chemical fixation: The interlayer phosphate groups (-PO4H2) form stable coordination compounds with metal ions, permanently fixing them.

[0055] (3) Synergistic blocking: It cooperates with the interface network of the silane coupling agent to form a triple ion blocking path of "adsorption-fixation-blocking", effectively blocking the PID degradation path.

[0056] Acid neutralization and free radical scavenging system (magnesium hydroxide and magnesium oxide)

[0057] Acid neutralization-free radical capture system composed of magnesium hydroxide (MH) and magnesium oxide (MgO) (1) Acid-base neutralization: The weak alkalinity of MH (pH = 9-10) can neutralize the acidic substances (such as HCl, HF) produced by degradation. The reaction equation is: Mg(OH)2+2HCl→MgCl2+2H2O.

[0058] (2) Free radical capture: MgO surface defect sites can capture alkyl radicals (·R) and peroxy radicals (·OOR) generated by polymer chain breakage, terminating the chain degradation reaction.

[0059] (3) Anti-water vapor penetration: MH / MgO particles form a tortuous path in the matrix, which reduces the water vapor diffusion coefficient by 30-40% and improves the water vapor resistance.

[0060] Antioxidant synergistic protection system (antioxidant 1076 and MH / MgO system compound)

[0061] Antioxidant 1076 forms a synergistic antioxidant network with MH / MgO:

[0062] (1) Main antioxidant effect: The hindered phenol group (-OH) of 1076 provides active hydrogen, captures peroxyl radicals and converts them into stable phenoloxyl radicals.

[0063] (2) Auxiliary antioxidant effect: MH / MgO removes hydroperoxide (ROOH) through physical adsorption, preventing its decomposition and generating new free radicals.

[0064] (3) Synergistic effect: The combination of the two can achieve an antioxidant efficiency (SE) of 1.5-1.8 (SE is <1.0 when used alone), significantly delaying thermal oxidative aging and inhibiting yellowing.

[0065] Core features: This system perfectly combines the functionality of inorganic fillers with the processing properties of organic matrices through a multi-stage action mechanism of "physical dispersion-chemical bonding-functional synergy", achieving a comprehensive improvement in the overall performance of the film.

[0066] The following are specific recipe examples and test results:

[0067] The preparation of composite functional masterbatch is shown in Table 1:

[0068] Table 1

[0069]

[0070]

[0071] Preparation method:

[0072] 1. Magnesium hydroxide and magnesium oxide are pre-surface coated, and the coating process is: dry high-speed mixing coating process (existing technology), preheating (80°C × 10min, 800rpm, remove moisture, activate the surface) → spray coating agent (silane coupling agent and ethanol mixture, uniform wet hot particles) → mixing reaction (3000rpm × 15min, 85°C, promote condensation) → aging (120°C × 30min, hot air circulation, solidify the coating layer);

[0073] 2. Material preparation: magnesium hydroxide and magnesium oxide powders that have been subjected to a surface coating process are weighed with zirconium hydrogen phosphate, antioxidant 1076, and KH570 according to the proportions in Table 1, and premixed to obtain a premix;

[0074] 3. Melt blending: Mix the EVA resin with the above premix, add it to the twin-screw extruder, melt blend it, and set the granulation temperature to 80-90℃;

[0075] 4. Underwater pelletizing: The extruded melt is cooled in a water tank and then pelletized, mixed in a mixing bin and dried to a moisture content of <0.2%.

[0076] The performance data is shown in Table 2 below:

[0077] Table 2

[0078]

[0079] The comparative experimental data are shown in Table 3 below:

[0080] Table 3

[0081]

[0082]

[0083] Peel force test method and conditions:

[0084] 1. Use clean ultra-clear embossed tempered glass 2 with a thickness of 3.2mm and a transmittance of more than 91.5% in the 380-1100nm band, two layers of photovoltaic encapsulation film 1 and back sheet 3 to laminate together. Figure 2 As shown, the sizes of the three materials are all 30*20cm.

[0085] 2. Cut the backsheet 3 or the combined layer of the backsheet 3 and the photovoltaic encapsulation film 1 into specimens with a width of 10±0.5mm at 5mm intervals on the long side for peeling force testing between the photovoltaic encapsulation film 1 and the backsheet 3 or between the photovoltaic encapsulation film 1 and the glass 2.

[0086] 3. According to the test method of GB / T2790-1995, the peeling force between the glass 2 and the photovoltaic encapsulation film 1 or between the back sheet 3 and the photovoltaic encapsulation film 1 is measured on a tensile testing machine at a tensile speed of 100±10 mm / min.

[0087] Key points of the process:

[0088] Since composite functional masterbatches come in many qualities and in different proportions, attention should be paid to the uniformity of the mixing during granulation. Powders with a small addition amount can be pre-mixed with powders with a larger addition amount.

[0089] Cost-effectiveness:

[0090] The addition of 1-2wt% of composite functional masterbatch increases the mixing uniformity of the EVA film formula, reduces the film factory's incoming material inspection cost by about 50%, and reduces the granulation cost by about 66.67%.

[0091] Suitable for double-glass components.

[0092] From the comparative experimental data in Table 3 above, we can see that:

[0093] The inventors conducted 10 sets of comparative experiments to systematically explore the effects of inorganic particle size control and granulation process optimization on the peeling performance of photovoltaic encapsulation film PCT before and after aging. The experimental variables included:

[0094] 1. Particle size parameters: Particle size control of magnesium hydroxide (MH), magnesium oxide (MgO), and zirconium hydrogen phosphate (ZHP) (<6um VS>20um).

[0095] It can be seen from the examples that the particle size sensitivity should be magnesium hydroxide (MH) > magnesium oxide (MgO) > zirconium hydrogen phosphate (ZHP). It can be seen from the comparison of Example 2 with Example 1 that when composite granulation is performed and the particle size is larger, the various peeling forces of the material are significantly lower than those of Example 1 with a smaller particle size. This may be because the smaller particle size increases the contact area between the components, making the structure of the material more compact, thereby improving the adhesion and weather resistance of the material.

[0096] 2. Granulation method: full component composite granulation vs single component separate granulation (rest composite)

[0097] Comparing the granulation of a single component and the composite granulation of other components, the granulation of magnesium hydroxide (MH) alone has the greatest impact on the peeling force of PCT after aging, which decreases by 22.2%, indicating that the melt-synergistic dispersion of magnesium hydroxide (MH) and other components is crucial to the interface stability; the performance of antioxidant 1076 decreases the least when granulated alone, indicating that it has good migration and diffusion ability in the matrix; zirconium hydrogen phosphate (ZHP) alone still maintains 96.1% of the peeling force of PCT after aging, which may be related to the self-dispersion characteristics of its layered structure.

[0098] 3. Performance indicators: initial peeling strength from glass, initial peeling strength from backsheet and peeling strength after PCT aging (121℃ / 100%RH / 2atm)

[0099] The effect of increasing the single particle size on the peeling performance can be seen from Table 3 above. When the particle size of zirconium hydrogen phosphate (ZHP) increases, the peeling force of PCT after aging is the highest, indicating that its aging resistance is not sensitive to changes in particle size.

[0100] Composite granulation is significantly superior to separate granulation, enabling better mixing of the components and forming a more stable structure, thereby improving film performance. In terms of particle size, smaller particles (less than 6 μm) significantly improve the film's initial adhesion and weather resistance. Larger particles (greater than 20 μm) also improve performance to a certain extent, but not to the same degree. This is because smaller particle sizes increase the interaction between the components, resulting in a denser and more uniform film structure, making it more resistant to environmental influences.

[0101] Based on the above analysis, a formulation with fully composited granulation and magnesium hydroxide, magnesium oxide, and zirconium hydrogen phosphate particles less than 6 μm can achieve optimal initial peel strength from glass and backsheet, as well as peel strength after PCT treatment. This formulation offers significant advantages in improving the film's adhesion and weather resistance.

[0102] The applicant declares that the present invention uses the above-described embodiments to illustrate the detailed process flow of the present invention, but the present invention is not limited to the above-described detailed process flow, that is, it does not mean that the present invention must rely on the above-described detailed process flow to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for various raw materials in the products of the present invention, additions of auxiliary ingredients, and selection of specific methods, etc., are all within the scope of protection and disclosure of the present invention.

Claims

1. A new type of composite functional masterbatch, characterized in that: Calculated by mass percentage, the novel composite functional masterbatch comprises the following components: EVA resin, 75-85%; Acid absorption aid, 9.1-20%; Anti-PID additive, 0.1-3%; Anti-aging additives, 0.1-2%; Silane coupling agent, 0.005-1%.

2. The novel composite functional masterbatch according to claim 1, characterized in that: Calculated by mass percentage, the acid absorption auxiliary agent includes: 9-15% of magnesium hydroxide and 0.1-5% of magnesium oxide.

3. The novel composite functional masterbatch according to claim 1, characterized in that: The anti-PID auxiliary agent is zirconium hydrogen phosphate.

4. The novel composite functional masterbatch according to claim 1, characterized in that: The anti-aging aid is antioxidant 1076.

5. The novel composite functional masterbatch according to claim 1, characterized in that: The silane coupling agent is KH570.

6. The novel composite functional masterbatch according to claim 1, characterized in that: The particle sizes of the magnesium hydroxide, magnesium oxide and zirconium hydrogen phosphate are all greater than 20 μm.

7. The novel composite functional masterbatch according to claim 1, characterized in that: The particle sizes of the magnesium hydroxide, magnesium oxide and zirconium hydrogen phosphate are all less than 6 μm.

8. The method for preparing the novel composite functional masterbatch according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: The acid-absorbing auxiliary agent is pre-surface coated by a dry high-speed mixing coating process; Premixing the acid-absorbing auxiliary agent powder that has been subjected to a surface coating process with an anti-PID auxiliary agent, an anti-aging auxiliary agent, and a silane coupling agent to obtain a premix; The EVA resin is mixed with the above premix, added into a twin-screw extruder, melt-blended, extruded and granulated to obtain the novel composite functional masterbatch.

9. The use of the novel composite functional masterbatch according to any one of claims 1 to 7, characterized in that: Used to prepare photovoltaic encapsulation films.

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