PVB (Polyvinyl Butyral) resin and PVB film for packaging solar photovoltaic module as well as preparation method and application of PVB resin and PVB film

Abstract

The invention belongs to the technical field of photovoltaic module packaging materials, and particularly relates to PVB (polyvinyl butyral) resin and a PVB film for packaging a solar photovoltaic module as well as a preparation method and application of the PVB resin and the PVB film. The preparation method of the PVB resin comprises the following steps: adding an emulsifier, hydrochloric acid and n-butyraldehyde dissolved with an antioxidant into a PVA solution, carrying out a condensation reaction, adjusting the pH value to 3.8-4.1, adding water at 40-45 DEG C for washing until the pH value is neutral, and drying to obtain the PVB resin. According to the PVB resin provided by the invention, alkali liquor is not added in the washing stage, the PVB resin has extremely low metal ion content, the prepared PVB film for packaging the solar photovoltaic module is high in volume resistivity, high in transparency and good in weather resistance, long-time and high-efficiency operation of the photovoltaic module can be ensured, and the PVB film is good in mechanical property, moderate in hardness, large in tensile strength and good in weather resistance. The application requirements in the solar photovoltaic field are met, and the application prospect is good.

Description

Technical Field

[0001] The invention belongs to the technical field of photovoltaic module packaging materials, and specifically relates to a PVB resin and a PVB film for solar photovoltaic module packaging, and a preparation method and application thereof. Background Art

[0002] As a transparent adhesive film for photovoltaic module encapsulation, a cross-linkable ethylene-vinyl acetate (EVA) system is often used. However, one disadvantage of this system is that during the curing process, corrosive substances such as acid are often released, which will damage the photosensitive semiconductor layer. In addition, EVA has poor anti-aging performance, and its service life does not match the module. Moreover, the yellowing of EVA will affect the power generation of the module system. PVB (polyvinyl butyral) film is a non-cross-linked thermoplastic plastic, which shows higher penetration resistance and better fracture resistance.

[0003] PVB film is also called PVB film or PVB interlayer. It is the best material for making laminated safety glass. PVB film is made of PVB resin, which is non-toxic, odorless, non-corrosive, and non-flammable. It has good light transmittance, insulation, weather resistance, wear resistance, water resistance, oil resistance, and aging resistance. It has special adhesion and light transmittance to inorganic and organic glass. Therefore, PVB film is widely used in automobiles, buildings, various bulletproof glass, flying spacecraft, military instruments, solar cells, and industrial composite shock-absorbing steel plates.

[0004] Chinese invention patent publication number CN113683969A discloses a PVB film, which includes the following components in parts by mass: 68-74 parts of PVB resin, 26-30 parts of plasticizer, 0.1-0.3 parts of antioxidant, 0.1-0.3 parts of light stabilizer, 0.03-0.07 parts of adhesion regulator, and 0.004-0.008 parts of coupling agent. The adhesion regulator is at least one of 1,2-pentanediol and monoglyceride of citrate. The PVB film prepared by the invention has good adhesion to glass. When the film is assembled under the condition of a moisture content of 2%, the knocking grade of the laminated glass can still reach above level 4; the edges will not debond in 72-hour boiling and 28-day humidity resistance tests, and it has excellent wet adhesion.

[0005] Another Chinese invention patent publication number CN116875225A discloses a PVB film with excellent bonding performance and a preparation method thereof. The scheme first uses PVA and n-butyraldehyde as reaction raw materials, and introduces chain extender A during the reaction process to prepare a high molecular weight PVB resin, thereby improving the bonding and mechanical properties of the PVB film; a two-step method is used to increase the molecular weight of the PVB resin. First, chain extender A is introduced into the condensation reaction of PVA and butyraldehyde to generate PVB resin, and then chain extender B is used to mix and evenly melt-extrude to further achieve chain extension. The prepared PVB film not only has excellent bonding performance, but also has good flame retardant properties, and can be used for laminated glass.

[0006] Another Chinese invention patent publication number CN107955304A discloses a photovoltaic PVB resin and a production method thereof, and a method for producing photovoltaic PVB film using the resin powder, which comprises: using 4,5-epoxytetrahydrophthalic acid dioctyl (2-ethylhexyl) ester as an internal plasticizer, reacting with the hydroxyl groups on PVB, and finally grafting it into the PVB molecular chain in the form of a side group to play a self-lubricating role. The obtained photovoltaic PVB film has higher fluidity, lower hygroscopicity and higher resistivity.

[0007] However, the optical transparency, aging resistance and insulation performance of the PVB film prepared by the above invention patent are average. Therefore, the art urgently needs to provide a photovoltaic PVB film with good mechanical properties, moderate hardness and high tensile strength to meet the application requirements of the solar photovoltaic field. Summary of the invention

[0008] In view of the problems existing in the prior art, the present invention provides a PVB resin and a PVB film for encapsulating a solar photovoltaic module and a preparation method and application thereof.

[0009] A PVB resin for encapsulating solar photovoltaic modules, the preparation method of which comprises the following steps:

[0010] First, add an emulsifier, hydrochloric acid and an antioxidant dissolved in n-butyraldehyde to the PVA solution to carry out a condensation reaction, then adjust the pH to 3.8-4.1, add 40-45° C. water for washing until the pH is neutral, and dry to obtain the product.

[0011] Preferably, the preparation process of the PVA solution comprises soaking the PVA in water at 20-30°C for 15-25 minutes, heating to 90-100°C, keeping warm for 1.5-2.5 hours to obtain a solution with a solid content of 6-12%, filtering, and then cooling the filtrate to 7-15°C.

[0012] Preferably, the mass ratio of the PVA, emulsifier, hydrochloric acid, n-butyraldehyde and antioxidant is 160-170:1:20-30:90-100:0.4-0.5.

[0013] More preferably, the mass ratio of the PVA, emulsifier, hydrochloric acid, n-butyraldehyde and antioxidant is 165-170:1:20-35:90-95:0.45-0.5.

[0014] Further preferably, the mass ratio of the PVA, emulsifier, hydrochloric acid, n-butyraldehyde and antioxidant is 165:1:24:94:0.5.

[0015] Preferably, the emulsifier is selected from one or more of sodium dodecylbenzene sulfonate, sodium dioctyl sulfosuccinate, sodium lauryl sulfate and alkylphenol polyoxyethylene ether.

[0016] Preferably, the alkylphenol polyoxyethylene ether is dodecylphenol polyoxyethylene ether, nonylphenol polyoxyethylene ether or hexadecylphenol polyoxyethylene ether.

[0017] More preferably, the emulsifier is sodium dioctyl sulfosuccinate.

[0018] Preferably, the mass concentration of the hydrochloric acid is 30-40%.

[0019] Preferably, the antioxidant is selected from one or more of 2,6-di-tert-butyl-p-methylphenol, β-(4-hydroxy-3,5-di-tert-butylphenyl) propionate, pentaerythritol tetrakis[methyl-β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl)hexanediamine and triethylene glycol bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate].

[0020] More preferably, the antioxidant is n-octadecyl β-(4-hydroxy-3,5-di-tert-butylphenyl) propionate.

[0021] Preferably, the condensation reaction process includes first reacting for 0.5-1.5 hours, then heating to 30-40° C. and keeping warm for 1-1.5 hours, and finally heating to 60-70° C. and keeping warm for 1-1.5 hours.

[0022] Preferably, the pH is adjusted using a sodium hydroxide solution with a mass concentration of 30-35%, and after the pH is adjusted to 3.8-4.1, the solution needs to be kept warm at 60-70°C for 0.5-1h.

[0023] Preferably, the resin is washed 2-3 times with water at 18-25° C. before drying, and the drying is performed until the moisture content of the PVB resin is less than 1.2%.

[0024] Preferably, the polymerization degree of the PVA is 1200-1800, the alcoholysis degree of the PVA is higher than 98%, the pH of the water is 6.8-7.2, and the conductivity of the water is less than 2.0 μS / cm.

[0025] The present invention also provides a PVB film for encapsulating solar photovoltaic modules, comprising the following components: the above-mentioned PVB resin for encapsulating solar photovoltaic modules, a plasticizer, an ultraviolet absorber, a light stabilizer, a mixture of hindered phenol antioxidants and phosphite antioxidants, and a silane coupling agent.

[0026] Preferably, the plasticizer includes one or more of trioctyl trimellitate, dioctyl terephthalate, triethylene glycol diisooctanoate, di(2-ethylhexyl) phthalate, dioctyl adipate, dioctyl sebacate and diisooctyl phthalate.

[0027] More preferably, the plasticizer is selected from one or more of trioctyl trimellitate, dioctyl terephthalate, triethylene glycol diisooctyl ester and diisooctyl phthalate.

[0028] More preferably, the plasticizer is a mixture of dioctyl terephthalate and triethylene glycol diisooctanoate in a mass ratio of 1:1.

[0029] Preferably, the ultraviolet absorber includes at least one of benzophenone, benzotriazole and triazine ultraviolet absorbers.

[0030] More preferably, the ultraviolet absorber includes at least one of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2'-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole and 2-(2'-hydroxy-3',5'-di-tert-pentylphenyl)benzotriazole.

[0031] More preferably, the ultraviolet absorber is 2'-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole.

[0032] Preferably, the light stabilizer includes one or more of UV-3581, light stabilizer 744, light stabilizer 770, light stabilizer 944 and light stabilizer LA-63.

[0033] Preferably, the hindered phenol antioxidant includes at least one of 2,6-di-tert-butyl-p-methylphenol, β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl)hexanediamine and triethylene glycol bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate].

[0034] More preferably, the hindered phenol antioxidant is selected from octadecanol β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] or triethylene glycol bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate].

[0035] More preferably, the hindered phenol antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0036] Preferably, the phosphite antioxidant includes at least one of diphenyl isooctyl phosphite, tris[2,4-di-tert-butylphenyl]phosphite, bisphenol A phosphite and triphenyl phosphite.

[0037] More preferably, the phosphite antioxidant is tris[2,4-di-tert-butylphenyl]phosphite.

[0038] Preferably, the mass ratio of the hindered phenol antioxidant to the phosphite antioxidant is 1:0.5-1.5.

[0039] More preferably, the mass ratio of the hindered phenol antioxidant to the phosphite antioxidant is 1:0.8-1.2.

[0040] Further preferably, the mass ratio of the hindered phenol antioxidant to the phosphite antioxidant is 1:.

[0041] Preferably, the silane coupling agent is N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, vinyltriethoxysilane or aminoethylaminoethylaminopropyltrimethoxysilane.

[0042] Preferably, the composition comprises the following components by weight: 100 parts of the above-mentioned PVB resin for encapsulating solar photovoltaic modules, 17-40 parts of a plasticizer, 0.05-0.5 parts of an ultraviolet absorber, 0.05-0.3 parts of a light stabilizer, 0.05-0.5 parts of a mixture of a hindered phenol antioxidant and a phosphite antioxidant, and 0.001-0.01 parts of a silane coupling agent.

[0043] More preferably, the composition comprises the following components, measured by mass: 100 parts of the above-mentioned PVB resin for encapsulating solar photovoltaic modules, 20-30 parts of a plasticizer, 0.1-0.4 parts of an ultraviolet absorber, 0.1-0.2 parts of a light stabilizer, 0.1-0.3 parts of a mixture of a hindered phenol antioxidant and a phosphite antioxidant, and 0.003-0.008 parts of a silane coupling agent.

[0044] Further preferably, the composition comprises the following components, calculated by mass: 100 parts of the above-mentioned PVB resin for encapsulating solar photovoltaic modules, 22 parts of a plasticizer, 0.2 parts of an ultraviolet absorber, 0.15 parts of a light stabilizer, 0.2 parts of a mixture of a hindered phenol antioxidant and a phosphite antioxidant, and 0.005 parts of a silane coupling agent.

[0045] The present invention also provides a method for preparing the above-mentioned PVB film for encapsulating solar photovoltaic modules, comprising the following steps: mixing and extruding the above-mentioned PVB resin for encapsulating solar photovoltaic modules, a plasticizer, an ultraviolet absorber, a light stabilizer, a mixture of hindered phenol antioxidants and phosphite antioxidants, and a silane coupling agent through an extruder at 150°C to obtain the obtained film.

[0046] Preferably, the screw speed of the extruder is 80-200 rpm.

[0047] More preferably, the screw speed of the extruder is 100-150 rpm.

[0048] The present invention also provides the use of the PVB film for solar photovoltaic module encapsulation or the PVB film for solar photovoltaic module encapsulation prepared by the above preparation method in the preparation of photovoltaic module encapsulation materials.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] (1) The PVB resin provided by the present invention does not require the addition of alkali solution during the water washing stage and has an extremely low metal ion content. The prepared PVB film for encapsulating solar photovoltaic modules has high volume resistivity, high transparency and good weather resistance, and can be used for encapsulating photovoltaic modules to ensure long-term and high-efficiency operation of photovoltaic modules.

[0051] (2) The PVB film for encapsulating solar photovoltaic modules provided by the present invention has good mechanical properties, moderate hardness and high tensile strength, meets the application requirements in the field of solar photovoltaics, and has good application prospects. DETAILED DESCRIPTION

[0052] It is worth noting that the raw materials used in the present invention are all common commercially available products, and the specifications and purchase sources of some raw materials are shown in Table 1.

[0053] Table 1 Raw material specifications and purchase sources

[0054] raw material Specification factory PVA15-99 The degree of polymerization is 1500 and the degree of alcoholysis is 99% Anhui Longyang Environmental Protection Technology Co., Ltd. PVA17-99 The degree of polymerization is 1700 and the degree of alcoholysis is 99% Shenzhen Boshun Chemical Co., Ltd. Butyraldehyde Content>99%, acid value<3mgKOH / g Dongguan Ruijing Chemical Co., Ltd. hydrochloric acid The mass fraction is 31% Taixing Meilan Chemical Co., Ltd. Pure water Conductivity <2.0us / cm, pH = 7 /

[0055] Example 1

[0056] A PVB resin for encapsulating solar photovoltaic modules, the raw material composition of which is shown in Table 2 by weight:

[0057] Table 2 Raw material composition and quantity of PVB resin for encapsulation of solar photovoltaic modules

[0058] A method for preparing PVB resin for encapsulating solar photovoltaic modules, comprising the following steps:

[0059] S1. Dissolution: Add PVA15-99 into pure water, soak at room temperature for 20 minutes, then heat to 97°C and keep warm for 2 hours to prepare PVA solution.

[0060] S2. Filtration and cooling: Filter the dissolved PVA solution into the condensation kettle and cool the filtrate to 10°C.

[0061] S3, feeding condensation: firstly dissolve the antioxidant in n-butyraldehyde to prepare a mixed solution, then add the emulsifier, hydrochloric acid and the mixed solution of n-butyraldehyde and antioxidant to the PVA solution in sequence to carry out a condensation reaction.

[0062] S4, temperature control reaction: keep the original temperature for 1 hour, slowly heat it to 35°C at a uniform speed over 1.5 hours, and keep it for 1 hour; then slowly heat it to 65°C at a uniform speed over 1.5 hours, and keep it for 1 hour; finally, add 32% sodium hydroxide solution, adjust pH to 4.1 to terminate the reaction, keep it for 0.5 hours, and then place the material in a water washing kettle for water washing.

[0063] S5. Washing: Add 45℃ pure water to wash for 30 minutes and then drain. Repeat the water washing 20 times until the pH value of the PVB resin is 7 and there is no chloride ion. Then wash twice with 20℃ pure water.

[0064] S6. Air drying: Dehydrate by centrifugal drying machine and dry in air drying tower to make the moisture content of PVB resin powder below 1.2%.

[0065] Example 2

[0066] A PVB resin for encapsulating a solar photovoltaic module is the same as that in Example 1, except that PVA15-99 is replaced by PVA17-99. The raw material composition thereof is shown in Table 3 by weight:

[0067] Table 3 Raw material composition and quantity of PVB resin for encapsulation of solar photovoltaic modules

[0068] Example 3

[0069] A PVB resin for encapsulating a solar photovoltaic module is the same as that in Example 1, except that the emulsifier is nonylphenol polyoxyethylene ether. The raw material composition thereof is shown in Table 4 by weight:

[0070] Table 4 Raw material composition and quantity of PVB resin for encapsulation of solar photovoltaic modules

[0071]

[0072] Example 4

[0073] A PVB resin for encapsulating a solar photovoltaic module is the same as Example 1, except that the composition ratio is different. The raw material composition is shown in Table 5:

[0074] Table 5 Raw material composition and quantity of PVB resin for encapsulation of solar photovoltaic modules

[0075]

[0076] Example 5

[0077] A PVB film for encapsulating solar photovoltaic modules, the raw material composition of which is shown in Table 6 by weight:

[0078] Table 6 Raw material composition and quantity of PVB film for encapsulating solar photovoltaic modules

[0079]

[0080] A method for preparing a PVB film for encapsulating a solar photovoltaic module comprises the following steps: setting the extrusion temperature of a venting twin-screw extruder to 150°C and the screw speed to 100 rpm, mixing and casting the above raw materials through the extruder to obtain a PVB film.

[0081] Example 6

[0082] A PVB film for encapsulating solar photovoltaic modules is the same as Example 5, except that the plasticizer is triethylene glycol diisooctanoate. The raw material composition thereof is shown in Table 7 by weight:

[0083] Table 7 Raw material composition and quantity of PVB film for encapsulating solar photovoltaic modules

[0084]

[0085]

[0086] Example 7

[0087] A PVB film for encapsulating a solar photovoltaic module is the same as Example 5, except that the PVB resin is the PVB resin prepared in Example 2. The raw material composition thereof is shown in Table 8 by weight:

[0088] Table 8 Raw material composition and quantity of PVB film for encapsulating solar photovoltaic modules

[0089]

[0090] Example 8

[0091] A PVB film for encapsulating solar photovoltaic modules is the same as Example 5, except that the amount of plasticizer is changed. The raw material composition thereof is shown in Table 9 by weight:

[0092] Table 9 Raw material composition and quantity of PVB film for encapsulating solar photovoltaic modules

[0093]

[0094] A method for preparing a PVB film for encapsulating a solar photovoltaic module comprises the following steps: setting the temperature of a venting twin-screw extruder to 150°C and the screw speed to 100 rpm, mixing and casting the above raw materials through the extruder to obtain a PVB film.

[0095] Example 9

[0096] A method for preparing laminated glass using the PVB film prepared in Example 5, comprising the following steps:

[0097] The PVB film prepared in Example 4 was placed between two sheets of 2.5 mm thick float glass. The film was cold-drawn for 30 min at a pressure of -0.1 to -0.09 MPa. The temperature and pressure were then increased for 20 min to a pressure of 1.2 MPa and a temperature of 140°C. The temperature and pressure were maintained at this constant temperature and pressure for 40 min to obtain laminated glass.

[0098] Comparative Example 1

[0099] A PVB resin for encapsulating solar photovoltaic modules is the same as Example 1, except that in step S5, after the resin pH is 7, alkali washing is performed. The raw material composition thereof is shown in Table 10 by weight:

[0100] Table 10 Raw material composition and quantity of PVB resin for encapsulation of solar photovoltaic modules

[0101]

[0102] A method for preparing PVB resin for encapsulating solar photovoltaic modules, comprising the following steps:

[0103] S1. Dissolution: Add PVA15-99 into pure water, soak at room temperature for 20 minutes, then heat to 97°C and keep warm for 2 hours to prepare PVA solution.

[0104] S2. Filtration and cooling: Filter the dissolved PVA solution into the condensation kettle and cool the filtrate to 10°C.

[0105] S3, feeding condensation: firstly dissolve the antioxidant in n-butyraldehyde to prepare a mixed solution, then add the emulsifier, hydrochloric acid and the mixed solution of n-butyraldehyde and antioxidant to the PVA solution in sequence to carry out a condensation reaction.

[0106] S4, temperature control reaction: keep the original temperature for 1 hour, slowly heat it to 35°C at a uniform speed over 1.5 hours, and keep it for 1 hour; then slowly heat it to 65°C at a uniform speed over 1.5 hours, and keep it for 1 hour; finally, add 32% sodium hydroxide solution, adjust pH to 4.1 to terminate the reaction, keep it for 0.5 hours, and then place the material in a water washing kettle for water washing.

[0107] S5. Washing: Add 45°C pure water to wash for 30 minutes and then drain. Repeat the washing 20 times until the pH value of the PVB resin is 7 and there is no chloride ion. Then add 32% sodium hydroxide solution to adjust the pH value to 13, soak for 2 hours, and then wash with 20°C pure water to pH = 10.

[0108] S6. Air drying: Dehydrate by centrifugal drying machine and dry in air drying tower to make the moisture content of PVB resin powder below 1.2%.

[0109] Comparative Example 2

[0110] A PVB resin for encapsulating a solar photovoltaic module is the same as that of Example 1, except that the washing conditions in step S5 are different.

[0111] A method for preparing PVB resin for encapsulating solar photovoltaic modules, comprising the following steps:

[0112] S1. Dissolution: Add PVA15-99 into pure water, soak at room temperature for 20 minutes, then heat to 97°C and keep warm for 2 hours to prepare PVA solution.

[0113] S2. Filtration and cooling: Filter the dissolved PVA solution into the condensation kettle and cool the filtrate to 10°C.

[0114] S3, feeding condensation: firstly dissolve the antioxidant in n-butyraldehyde to prepare a mixed solution, then add the emulsifier, hydrochloric acid and the mixed solution of n-butyraldehyde and antioxidant to the PVA solution in sequence to carry out a condensation reaction.

[0115] S4, temperature control reaction: keep the original temperature for 1 hour, slowly heat it to 35°C at a uniform speed over 1.5 hours, and keep it for 1 hour; then slowly heat it to 65°C at a uniform speed over 1.5 hours, and keep it for 1 hour; finally, add 32% sodium hydroxide solution, adjust pH to 4.1 to terminate the reaction, keep it for 0.5 hours, and then place the material in a water washing kettle for water washing.

[0116] S5. Washing: Add 25℃ pure water and wash for 30 minutes, then drain. Repeat the water washing 12 times, and then wash twice with 20℃ pure water.

[0117] S6. Air drying: Dehydrate by centrifugal drying machine and dry in air drying tower to make the moisture content of PVB resin powder below 1.2%.

[0118] Comparative Example 3

[0119] A PVB resin for encapsulating a solar photovoltaic module is the same as Example 1, except that the amount of the emulsifier is 5 parts by mass. The raw material composition is shown in Table 11:

[0120] Table 11 Raw material composition and quantity of PVB resin for encapsulation of solar photovoltaic modules

[0121]

[0122] Comparative Example 4

[0123] A PVB film for encapsulating a solar photovoltaic module is the same as Example 5, except that the PVB resin is the PVB resin prepared in Comparative Example 1. The raw material composition thereof is shown in Table 12 by weight:

[0124] Table 12 Raw material composition and quantity of PVB film for encapsulating solar photovoltaic modules

[0125]

[0126]

[0127] Comparative Example 5

[0128] A PVB film for encapsulating a solar photovoltaic module is the same as Example 5, except that the PVB resin is the PVB resin prepared in Comparative Example 2. The raw material composition thereof is shown in Table 13 by weight:

[0129] Table 13 Raw material composition and quantity of PVB film for encapsulating solar photovoltaic modules

[0130]

[0131] Comparative Example 6

[0132] A PVB film for encapsulating solar photovoltaic modules is the same as Example 5, except that the plasticizer is 42 parts of triethylene glycol diisooctanoate. The raw material composition is shown in Table 14 by mass:

[0133] Table 14 Raw material composition and quantity of PVB film for encapsulating solar photovoltaic modules

[0134]

[0135] Test Example 1

[0136] The sodium ion content of the PVB resin for solar photovoltaic module encapsulation prepared in Examples 1-4 and Comparative Examples 1-3 was measured respectively. The sodium ion content was measured according to JY / T0567-2020 "General Rules for Inductively Coupled Plasma Emission Spectroscopy Analysis Methods". The measurement results are shown in Table 15.

[0137] Table 15 Sodium ion content of PVB resin prepared in Examples 1-4 and Comparative Examples 1-3

[0138] serial number Sodium ion content (mg / kg) Example 1 10 Example 2 9 Example 3 7 Example 4 8 Comparative Example 1 78 Comparative Example 2 69 Comparative Example 3 38

[0139] It can be seen from Example 1 and Comparative Examples 1-3 that by changing the water washing conditions or the amount of emulsifier added, the sodium ion content of the prepared PVB resin is significantly lower than that of the comparative example, and has an extremely low metal ion content, so that the extruded PVB film has a higher volume resistivity.

[0140] Test Example 2

[0141] The PVB films for solar photovoltaic module encapsulation prepared in Examples 5-8 and Comparative Examples 4-6 were tested for transmittance, haze, tensile strength, elongation at break and volume resistivity, respectively, and the reference standards are as follows:

[0142] Light transmittance and haze: measured according to GB / T 2410-2008 "Determination of light transmittance and haze of transparent plastics";

[0143] Tensile strength and elongation at break: measured according to GB / T 1040.3-2016 "Test for tensile properties of plastics";

[0144] Volume resistivity: Determined according to GB / T 1410-2006 “Test method for volume resistivity and surface resistivity of solid insulating materials”.

[0145] The performance test results are shown in Table 16:

[0146] Table 16 Performance test results of PVB films prepared in Examples 5-8 and Comparative Examples 4-6

[0147]

[0148]

[0149] It can be seen from Table 16 that the PVB films prepared in Examples 5 to 8 are superior to those in Comparative Examples 4 to 6 in terms of transmittance, haze, tensile strength, elongation at break and volume resistivity. That is, the PVB film for solar photovoltaic module encapsulation provided by the present invention has good mechanical properties, moderate hardness and high tensile strength, meets the application requirements in the field of solar photovoltaics, and has good application prospects.

[0150] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A PVB resin for encapsulating solar photovoltaic modules, characterized in that: The preparation method of the PVB resin comprises the following steps: firstly, adding an emulsifier, hydrochloric acid and n-butyraldehyde containing an antioxidant into a PVA solution to carry out a condensation reaction, then adjusting the pH to 3.8-4.1, adding 40-45° C. water for washing until the pH is neutral, and drying to obtain the PVB resin.

2. The PVB resin for encapsulating solar photovoltaic modules according to claim 1, characterized in that: The preparation process of the PVA solution comprises soaking the PVA in water at 20-30° C. for 15-25 minutes, heating to 90-100° C., keeping warm for 1.5-2.5 hours to obtain a solution with a solid content of 6-12%, filtering, and then cooling the filtrate to 7-15° C. to obtain the solution.

3. The PVB resin for encapsulating solar photovoltaic modules according to claim 2, characterized in that: The mass ratio of the PVA, emulsifier, hydrochloric acid, n-butyraldehyde and antioxidant is 160-170:1:20-30:90-100:0.4-0.

5.

4. The PVB resin for encapsulating solar photovoltaic modules according to claim 1, characterized in that: The emulsifier is selected from one or more of sodium dodecylbenzene sulfonate, sodium dioctyl sulfosuccinate, sodium lauryl sulfate and alkylphenol polyoxyethylene ether, and the alkylphenol polyoxyethylene ether is dodecylphenol polyoxyethylene ether, nonylphenol polyoxyethylene ether or hexadecylphenol polyoxyethylene ether.

5. The PVB resin for encapsulating solar photovoltaic modules according to claim 1, characterized in that: The mass concentration of the hydrochloric acid is 30-40%, and the antioxidant is selected from one or more of 2,6-di-tert-butyl-p-methylphenol, β-(4-hydroxy-3,5-di-tert-butylphenyl) propionate, pentaerythritol tetrakis[methyl-β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine and triethylene glycol bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate].

6. The PVB resin for encapsulating solar photovoltaic modules according to claim 1, characterized in that: The condensation reaction process includes reacting for 0.5-1.5h, heating to 30-40°C and keeping warm for 1-1.5h, and finally heating to 60-70°C and keeping warm for 1-1.5h; the pH is adjusted using a sodium hydroxide solution with a mass concentration of 30-35%, and after the pH is adjusted to 3.8-4.1, it needs to be kept warm at 60-70°C for 0.5-1h; before drying, it needs to be washed with 18-25°C water for 2-3 times, and the drying is carried out until the moisture content of the PVB resin is less than 1.2%.

7. The PVB resin for encapsulating solar photovoltaic modules according to any one of claims 1 to 6, characterized in that: The polymerization degree of the PVA is 1200-1800, the alcoholysis degree of the PVA is higher than 98%, the pH of the water is 6.8-7.2, and the conductivity of the water is less than 2.0 μS / cm.

8. A PVB film for encapsulating solar photovoltaic modules, characterized in that: The invention comprises the following components: the PVB resin for encapsulating solar photovoltaic modules according to any one of claims 1 to 7, a plasticizer, an ultraviolet absorber, a light stabilizer, a mixture of a hindered phenol antioxidant and a phosphite antioxidant, and a silane coupling agent.

9. The PVB film for encapsulating solar photovoltaic modules according to claim 8, characterized in that: The plasticizer includes one or more of trioctyl trimellitate, dioctyl terephthalate, triethylene glycol diisooctanoate, di(2-ethylhexyl) phthalate, dioctyl adipate, dioctyl sebacate and diisooctyl phthalate.

10. The PVB film for encapsulating solar photovoltaic modules according to claim 8, characterized in that: The ultraviolet absorber includes at least one of benzophenone, benzotriazole and triazine ultraviolet absorbers; the light stabilizer includes one or more of UV-3581, light stabilizer 744, light stabilizer 770, light stabilizer 944 and light stabilizer LA-63.

11. The PVB film for encapsulating solar photovoltaic modules according to claim 10, characterized in that: The ultraviolet absorber includes at least one of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2'-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole and 2-(2'-hydroxy-3',5'-di-tert-pentylphenyl)benzotriazole.

12. The PVB film for encapsulating solar photovoltaic modules according to claim 8, characterized in that: The hindered phenol antioxidant includes at least one of 2,6-di-tert-butyl-p-methylphenol, β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine and triethylene glycol bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate]; the phosphite antioxidant includes at least one of diphenyl isooctyl phosphite, tris[2.4-di-tert-butylphenyl] phosphite, bisphenol A phosphite and triphenyl phosphite; the mass ratio of the hindered phenol antioxidant to the phosphite antioxidant is 1:0.5-1.

5.

13. The PVB film for encapsulating solar photovoltaic modules according to claim 8, characterized in that: The silane coupling agent is N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, vinyltriethoxysilane or aminoethylaminoethylaminopropyltrimethoxysilane.

14. The PVB film for encapsulating solar photovoltaic modules according to any one of claims 8 to 13, characterized in that: The invention comprises the following components in parts by mass: 100 parts of the PVB resin for encapsulating solar photovoltaic modules according to any one of claims 1 to 7, 17 to 40 parts of a plasticizer, 0.05 to 0.5 parts of an ultraviolet absorber, 0.05 to 0.3 parts of a light stabilizer, 0.05 to 0.5 parts of a mixture of a hindered phenol antioxidant and a phosphite antioxidant, and 0.001 to 0.01 parts of a silane coupling agent.

15. A method for preparing a PVB film for encapsulating a solar photovoltaic module according to any one of claims 8 to 14, characterized in that: The method comprises the following steps: mixing and extruding the PVB resin for encapsulating the solar photovoltaic module according to any one of claims 1 to 7, a plasticizer, an ultraviolet absorber, a light stabilizer, a mixture of a hindered phenol antioxidant and a phosphite antioxidant, and a silane coupling agent through an extruder to obtain the product.

16. Use of the PVB film for encapsulating a solar photovoltaic module according to any one of claims 8 to 14 or the PVB film for encapsulating a solar photovoltaic module prepared by the preparation method according to claim 15 in the preparation of photovoltaic module encapsulation materials.

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