阅读说明：本技术 一种用于太阳能电池的背板及制备方法 (Back plate for solar cell and preparation method ) 是由 罗吉江 符书臻 崔如玉 花超 朱瑜芳 于 2020-12-25 设计创作，主要内容包括：本发明开发了一种新的用于太阳能电池的背板的制备方法,先采用静电纺丝的方法制备骨架结构的B层,然后在B层的上下两面流延聚烯烃材料的A层和C层,然后在真空压膜机内进行层压,由于层压的温度高于A层和C层的熔融温度、且低于B层的软化温度,在压力下熔融的聚烯烃薄膜层可以穿透并填充纳米纤维网络,由于A层和C层的聚烯烃在硅烷偶联剂的作用下会发生接枝交联反应,使得上下2层聚烯烃发生局部交联,从而彻底提高了复合背板各层之间的粘合力,不仅彻底解决了各层之间的层间剥离力差的技术问题。(The invention has developed a new preparation method used for the slab of the solar cell, adopt the B layer of the method preparation skeleton structure of the electrostatic spinning first, then the A layer and C layer of the polyolefin material of upper and lower two sides curtain coating of B layer, then laminate in the vacuum film pressing machine, because the temperature of laminating is higher than the fusing temperature of A layer and C layer, and lower than the softening temperature of B layer, the polyolefin film layer melted under the pressure can penetrate and pack the nanofiber network, because the polyolefin of A layer and C layer will take place the graft cross-linking reaction under the influence of silane coupling agent, make the polyolefin of upper and lower 2 layers take place the local cross-linking, thus has improved the cohesive force among each layer of the composite slab completely, not only solved the poor technical problem of interlaminar stripping force among each layer completely.)

1. A method for preparing a back sheet for a solar cell, comprising the steps of:

(1) preparing a layer B: respectively adding a high-molecular spinning solution and an inorganic nano filler suspension into two injectors of an electrostatic spinning machine by adopting the electrostatic spinning machine, performing electrostatic spinning, and then drying to obtain a layer B; the thickness of the layer B is 20-100 microns;

the high-molecular spinning solution is a mixture of a high-molecular polymer and a solvent, the mass content of the high-molecular polymer is 20-40%, the high-molecular polymer is selected from one or more of PET, PA6 or PA66, and the solvent is 2,2, 2-trifluoroethanol, trifluoroacetic acid or hexafluoroisopropanol;

the inorganic nano filler suspension is a mixture of methanol and inorganic nano filler, the mass content of the inorganic nano filler is 5-20%, and the inorganic nano filler is selected from one or more of titanium dioxide, silicon oxide, aluminum oxide, magnesium oxide, zinc oxide, aluminum nitride, boron nitride, silicon carbide, aluminum hydroxide, barium sulfate, talcum powder and mica powder;

(2) carrying out surface treatment on the B layer by using a silane coupling agent;

(3) respectively putting the raw materials of the layer A and the layer C into 2 groups of screws of a screw extruder according to the following formula, respectively carrying out melt extrusion and tape casting on two sides of the layer B to form a film, thus obtaining a composite film with an A/B/C three-layer structure; the thicknesses of the layer A and the layer C are the same or different and are respectively 20-200 micrometers;

the layer A comprises the following raw materials in parts by mass:

the layer C comprises the following raw materials in parts by mass:

(4) placing the A/B/C three-layer composite film obtained in the step (3) into a vacuum film pressing machine, laminating at 180-220 ℃ under 3-20 MPa for 3-8 min, and naturally cooling to room temperature to obtain the back plate for the solar cell;

the temperature of the lamination is higher than the melting temperature of the A layer and the C layer and lower than the softening temperature of the B layer.

2. The method for producing a back sheet for a solar cell according to claim 1, wherein: and (2) after electrostatic spinning is carried out in the step (1), putting the product into a vacuum drying oven at 80 ℃ for drying for 24 hours to obtain a layer B.

3. The method for producing a back sheet for a solar cell according to claim 1, wherein: in the step (1), the two syringes are placed side by side, the distance between the midpoint of the two syringes and the collector is 15cm, the speed of the injection pump is 1-3 mL/h, and the voltage is 25 kilovolts.

4. The method for producing a back sheet for a solar cell according to claim 1, wherein: in the step (3), the temperature of the screw extruder is 160-200 ℃, and the rotating speed is 90-120 r/min.

5. The method for producing a back sheet for a solar cell according to claim 1, wherein: in the step (3), the compatilizer in the raw material formula of the layer A and the layer C is selected from one or more of PE-g-MAH, PP-g-MAH, POE-g-MAH and polyethylene-glycidyl methacrylate.

6. The method for producing a back sheet for a solar cell according to claim 1, wherein: in the step (3), the additives in the raw material formulas of the layer A and the layer C are a cross-linking agent, an initiator, an antioxidant, an ultraviolet absorbent and a light stabilizer.

7. The method for producing a back sheet for a solar cell according to claim 1, wherein: the thickness of the layer B is 20-40 micrometers; the thicknesses of the layer A and the layer C are the same or different and are respectively 30-40 micrometers; the total thickness of the three layers is less than 100 microns.

8. The method for producing a back sheet for a solar cell according to claim 1, wherein: in the step (4), the laminating pressure is 10-18 MPa, and the laminating time is 3-5 min.

9. The back sheet for a solar cell produced by the production method according to any one of claims 1 to 8.

10. A solar cell prepared from the backsheet of claim 9.

Technical Field

The invention relates to the technical field of solar cell backboard materials, in particular to a backboard for a solar cell and a preparation method thereof.

Background

At present, with the exhaustion of non-renewable energy and the growing environmental problem, solar energy as clean energy has received unprecedented attention and attention. Solar power generation (also called photovoltaic power generation) is one of the main ways to effectively utilize solar energy, and as a core component of solar power generation, the reliability of a solar cell (also called photovoltaic cell) directly determines the efficiency of solar power generation.

In the prior art, a solar cell generally comprises an upper cover plate, an adhesive film, a cell sheet, an adhesive film and a solar back plate. The back plate is an important part of the solar cell, plays a role in bonding and packaging the structure of the solar cell module on one hand, and protects the solar cell on the other hand, so that water vapor is prevented from permeating, the humidity-heat-aging resistance and the photoelectric conversion efficiency of the solar cell are improved, and the service life of the solar cell is prolonged. Because the solar energy backplate directly exposes in the air, the environmental condition of institute is abominable, therefore current product is multilayer composite construction: a substrate and a weatherable layer; the base plate mainly adopts polyester base materials or polyolefin, and most of the weather-resistant layers are fluorine-containing weather-resistant layers. However, the existing back plate mainly has the following problems: (1) the molecular main chain of the polyester contains a large amount of ester groups, so that the polyester is easy to hydrolyze, and even if the polyester is modified, the requirement on the humidity and heat aging resistance of the solar backboard is still difficult to meet; (2) the fluorine-containing weather-resistant layer is expensive and has poor bonding performance, so that the interlayer peeling force between layers is poor; (3) the back sheet itself requires extremely high mechanical strength, low-temperature impact strength and toughness, and the existing back sheet material is difficult to be excellent in this respect.

Therefore, the development of the multilayer back plate which can meet the adhesive force between the back plate layers and simultaneously can ensure the requirements of high adhesive property, high mechanical strength and high and low temperature impact property of the back plate obviously has positive practical significance.

Disclosure of Invention

The invention aims to provide a back sheet for a solar cell and a preparation method thereof.

In order to achieve the purpose of the invention, the technical scheme adopted by the invention is as follows: a method for preparing a back sheet for a solar cell, comprising the steps of:

(1) preparing a layer B: respectively adding a high-molecular spinning solution and an inorganic nano filler suspension into two injectors of an electrostatic spinning machine by adopting the electrostatic spinning machine, performing electrostatic spinning, and then drying to obtain a layer B; the thickness of the layer B is 20-100 microns;

the high-molecular spinning solution is a mixture of a high-molecular polymer and a solvent, the mass content of the high-molecular polymer is 20-40%, the high-molecular polymer is selected from one or more of PET, PA6 or PA66, and the solvent is 2,2, 2-trifluoroethanol, trifluoroacetic acid or hexafluoroisopropanol;

the inorganic nano filler suspension is a mixture of methanol and inorganic nano filler, the mass content of the inorganic nano filler is 5-20%, and the inorganic nano filler is selected from one or more of titanium dioxide, silicon oxide, aluminum oxide, magnesium oxide, zinc oxide, aluminum nitride, boron nitride, silicon carbide, aluminum hydroxide, barium sulfate, talcum powder and mica powder;

(2) carrying out surface treatment on the B layer by using a silane coupling agent;

(3) respectively mixing the raw materials of the layer A and the layer C uniformly according to the following formula, then feeding the mixture into a screw extruder, respectively carrying out melt extrusion and tape casting on the two sides of the layer B to form a film, and obtaining a composite film with an A/B/C three-layer structure; the thicknesses of the layer A and the layer C are the same or different and are respectively 20-200 micrometers;

the layer A comprises the following raw materials in parts by mass:

the layer C comprises the following raw materials in parts by mass:

(4) placing the A/B/C three-layer composite film obtained in the step (3) into a vacuum film pressing machine, laminating at 180-220 ℃ under 3-20 MPa for 3-8 min, and naturally cooling to room temperature to obtain the back plate for the solar cell;

the temperature of the lamination is higher than the melting temperature of the A layer and the C layer and lower than the softening temperature of the B layer.

In the above, the mass content of the polymer in the polymer spinning solution is 20 to 40%, preferably 25 to 35%, and more preferably 28 to 32%.

In the above, the step of uniformly mixing the raw materials of the layer a and the layer C according to the following formula and then feeding the mixture into a screw extruder means that the raw materials of the layer a are uniformly mixed according to the formula and the raw materials of the layer C are uniformly mixed according to the formula; rather than a and C layers.

The mass content of the inorganic nano filler in the inorganic nano filler suspension is 5-20%, preferably 8-16%, and more preferably 10-13%.

Preferably, in the step (1), after electrostatic spinning, the product is dried in a vacuum drying oven at 80 ℃ for 24 hours to obtain the layer B.

Preferably, in the step (1), the two syringes are placed side by side, the midpoint of the two syringes is 15cm away from the collector, the speed of the injection pump is 1-3 mL/h, and the voltage is 25 kV.

Preferably, in the step (3), the temperature of the screw extruder is 160-200 ℃, and the rotating speed is 90-120 r/min.

Preferably, in the step (3), the compatilizer in the raw material formula of the layer A and the layer C is selected from one or more of PE-g-MAH, PP-g-MAH, POE-g-MAH and polyethylene-glycidyl methacrylate.

Preferably, in the step (3), the additives in the raw material formula of the layer a and the layer C are a cross-linking agent, an initiator, an antioxidant, an ultraviolet absorber and a light stabilizer.

Preferably, the thickness of the B layer is 20-40 micrometers; the thicknesses of the layer A and the layer C are the same or different and are respectively 30-40 micrometers; the total thickness of the three layers is less than 100 microns. Namely, the back plate of the invention is very thin, is smaller than the thickness of the existing back plate, and can ensure the strength of the back plate.

Preferably, in the step (4), the laminating pressure is 10-18 MPa, and the laminating time is 3-5 min.

The invention also discloses a back sheet for a solar cell prepared by the preparation method.

The invention also discloses a solar cell prepared from the back sheet.

The working mechanism of the invention is as follows: utilize two syringes to spray polymer spinning solution and inorganic nano filler turbid liquid simultaneously respectively, make inorganic nano filler particle can the homodisperse at synthetic nanofiber membrane surface to effectively avoided the reunion problem of inorganic nano filler in combined material, and made combined material's functional promotion: the nanofiber membrane prepared by electrostatic spinning is a three-dimensional porous non-woven fiber membrane formed by overlapping nanofibers, has a certain porosity, the temperature resistance of high polymer PET, PA6 and PA66 is superior to that of polyolefin materials, in addition, the rigidity and the tolerance of the high polymer are good, a nanofiber network formed by the high polymer can play a skeleton role in a composite backboard material, so that the rigidity of the backboard is increased, and the nanofiber membrane has the characteristics of high length-diameter ratio, large specific surface area, high molecular chain orientation and the like, so that the backboard is enhanced and toughened, and has good mechanical properties; in addition, the nanofiber membrane has heterogeneous nucleation effect in the preparation process of the back plate, the toughness of the back plate is improved, and the tensile strength and the Young modulus are increased.

On the other hand, the polyolefin film layer (A/C layer) is cast on the surface of the nanofiber film layer, when lamination is carried out in a vacuum film pressing machine, the lamination temperature is higher than the melting temperature of the A layer and the C layer and lower than the softening temperature of the B layer, the polyolefin film layer melted under pressure can penetrate and fill the nanofiber network (while the nanofiber film still keeps the original fiber shape), and thus the polyolefin filled composite material is prepared; in addition, because the surface of the layer B is treated by adopting the silane coupling agent, the polyolefin of the layer A and the polyolefin of the layer C which are contacted with the silane coupling agent can generate grafting crosslinking reaction during lamination, so that the materials of the layer A and the layer C can generate certain crosslinking reaction, the adhesive force between the layers of the composite back plate is thoroughly improved, the technical problem of poor interlayer stripping force between the layers is thoroughly solved, and the obtained composite back plate has better mechanical property.

Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages:

1. the invention has developed a new preparation method used for the slab of the solar cell, adopt the B layer of the skeleton texture of the method preparation of electrostatic spinning first, then the A layer and C layer of the polyolefin material of upper and lower two sides curtain coating of B layer, then laminate in the vacuum film press, because the temperature of laminating is higher than the melting temperature of A layer and C layer, and lower than the softening temperature of B layer, the polyolefin film layer melted under the pressure can penetrate and pack the nanofiber network, because the polyolefin of A layer and C layer will take place the graft cross-linking reaction under the influence of silane coupling agent, make the upper and lower 2 layers of polyolefin take place the local cross-linking, thus has improved the cohesive force among each layer of the composite slab completely, not only solved the poor technical problem of interlaminar stripping force among each layer completely;

2. experiments prove that compared with the prior art, the composite back plate obtained by the invention not only has better interlayer peeling force, but also has better mechanical strength, elastic modulus, high and low temperature impact property and excellent mechanical property;

3. the preparation process is simple and easy to implement, has low cost and is suitable for popularization and application.

Detailed Description

The invention is further described below with reference to the following examples:

example one

A method for preparing a back sheet for a solar cell, comprising the steps of:

layer A: 70 parts of block copolymer polypropylene (Beijing Yanshan petrochemical company), 30 parts of HDPE (Beijing Yanshan petrochemical company), 1 part of PP-g-MAH (Beijing addition auxiliary research institute), 1 part of PE-g-MAH (Beijing addition auxiliary research institute), 0.1 part of antioxidant 2, 6-tertiary butyl-4-methylphenol (Beijing addition auxiliary research institute), 0.2 part of ultraviolet absorbent 2-hydroxy-4-n-octoxy benzophenone (Beijing addition auxiliary research institute), 0.2 part of light stabilizer bis (2,2,6, 6-tetramethyl-4-piperidyl) sebacate (Beijing addition auxiliary research institute), and uniformly mixing;

layer B: dissolving PET in a trifluoroacetic acid solvent with the mass content of 20% to obtain a high-molecular spinning solution; dispersing nano titanium dioxide in methanol to prepare a titanium dioxide suspension with the mass content of 10%, and ultrasonically oscillating for 15 min;

adding the 2 mixed solutions into two side-by-side injectors of an electrostatic spinning machine respectively, performing electrostatic spinning at the speed of an injection pump of 1mL/h and the distance between the midpoint of the two injectors and a collector of 15cm and at the voltage of 20kV, and drying the product in a vacuum drying oven at 80 ℃ for 24h to obtain TiO₂PET nanofiber membrane with a membrane thickness of 20 microns;

then, the fiber membrane is subjected to surface treatment by using a silane coupling agent KH550 (organic silicon material industry Co., Ltd., Danyang);

layer C: 70 parts of homo-polypropylene (Beijing Yanshan petrochemical company), 30 parts of HDPE (Beijing Yanshan petrochemical company), 1 part of PP-g-MAH (Beijing addition auxiliary research institute), 1 part of PE-g-MAH (Beijing addition auxiliary research institute), 0.1 part of antioxidant 2, 6-tertiary butyl-4-methylphenol (Beijing addition auxiliary research institute), 0.2 part of ultraviolet absorbent 2-hydroxy-4-n-octoxy benzophenone (Beijing addition auxiliary research institute), and 0.2 part of light stabilizer bis (2,2,6, 6-tetramethyl-4-piperidyl) sebacate (Beijing addition auxiliary research institute), and the components are uniformly mixed;

respectively feeding the materials of the layer A and the layer C into 2 groups of screws of a screw extruder, controlling the temperature at 180 ℃ and the rotating speed at 100 rpm, performing melt extrusion and tape casting on the materials of the layer A and the layer C to obtain the final product₂Obtaining an A/B/C three-layer structure film on two sides of the PET nano fiber film, wherein the thicknesses of the layer A and the layer C are both 35 microns;

then, the laminated film is placed in a vacuum film pressing machine, lamination is carried out for 5min under the conditions of 200 ℃ and 18MPa, simultaneously, a vacuum pump is started to vacuumize the system, bubbles contained in the system are removed, and the melted layer A and the layer C permeate into a fiber network of the layer B; after completion of the hot pressing, it was naturally cooled to room temperature, to obtain a high-strength back sheet S1.

Example two

A method for preparing a back sheet for a solar cell, which is the same as the first embodiment except that: the resulting TiO₂The thickness of the/PET nanofiber membrane was 30 microns. The a and C layers were both 30 microns thick.

A high strength backsheet S2 was obtained.

EXAMPLE III

A method for preparing a back sheet for a solar cell, which is the same as the first embodiment except that: the resulting TiO₂The thickness of the/PET nanofiber membrane was 40 microns. The a and C layers were both 25 microns thick.

A high strength backsheet S3 was obtained.

Example four

A method for preparing a back sheet for a solar cell, which is the same as the first embodiment except that: laminating for 6min in a vacuum film pressing machine at 200 ℃ under 10MPa, and simultaneously starting a vacuum pump to vacuumize the system to remove bubbles contained in the system, wherein the molten layer A and the molten layer C are permeated into a fiber network of the layer B; after completion of the hot pressing, it was naturally cooled to room temperature, to obtain a high-strength back sheet S4.

EXAMPLE five

A method for preparing a back sheet for a solar cell, which is the same as the first embodiment except that: laminating for 8min in a vacuum film pressing machine at 200 ℃ under 4MPa, and simultaneously starting a vacuum pump to vacuumize the system to remove bubbles contained in the system, wherein the molten layer A and the molten layer C are permeated into a fiber network of the layer B; after completion of the hot pressing, it was naturally cooled to room temperature, to obtain a high-strength back sheet S5.

EXAMPLE six

Preparation method of back plate for solar cell, which is the same as that in example one, obtained TiO₂The thickness of the/PET nanofiber membrane was also 20 microns; is only oneThe method is characterized in that:

layer B: dissolving PA6 in 2,2, 2-trifluoroethanol solvent with the content of 20 wt% to obtain the high-molecular spinning solution. The other is also the same titanium dioxide suspension as in example one.

A high strength backsheet S6 was obtained.

Comparative example 1

A method for preparing a back sheet for a solar cell, which is the same as the first embodiment except that: the resulting TiO₂The thickness of the/PET nanofiber membrane was 15 microns. The a and C layers were both 35 microns thick.

A high strength backsheet D1 was obtained.

Comparative example No. two

A method for preparing a back sheet for a solar cell, which is the same as the first embodiment except that: the resulting TiO₂The thickness of the/PET nanofiber membrane was 100 microns. The a and C layers were both 100 microns thick.

A high strength backsheet D2 was obtained.

Comparative example No. three

A method for preparing a back sheet for a solar cell, comprising the steps of:

layer A: 70 parts of block copolymer polypropylene (Beijing Yanshan petrochemical company), 30 parts of HDPE (Beijing Yanshan petrochemical company), 1 part of PP-g-MAH (Beijing addition auxiliary research institute), 1 part of PE-g-MAH (Beijing addition auxiliary research institute), 0.1 part of antioxidant 2, 6-tertiary butyl-4-methylphenol (Beijing addition auxiliary research institute), 0.2 part of ultraviolet absorbent 2-hydroxy-4-n-octoxy benzophenone (Beijing addition auxiliary research institute), 0.2 part of light stabilizer bis (2,2,6, 6-tetramethyl-4-piperidyl) sebacate (Beijing addition auxiliary research institute), and uniformly mixing;

layer C, 70 parts of homopolymerized polypropylene (Beijing Yanshan petrochemical company), 30 parts of HDPE (Beijing Yanshan petrochemical company), 1 part of PP-g-MAH (Beijing addition auxiliary research institute), 1 part of PE-g-MAH (Beijing addition auxiliary research institute), 0.1 part of antioxidant 2, 6-tertiary butyl-4-methylphenol (Beijing addition auxiliary research institute), 0.2 part of ultraviolet absorbent 2-hydroxy-4-n-octoxy benzophenone (Beijing addition auxiliary research institute), 0.2 part of light stabilizer bis (2,2,6, 6-tetramethyl-4-piperidyl) sebacate (Beijing addition auxiliary research institute), and the components are uniformly mixed;

and respectively feeding the materials of the layer A and the layer C into 2 groups of screws of a screw extruder, controlling the temperature at 180 ℃ and the rotating speed at 100 rpm, and performing melt extrusion to obtain the A/C two-layer structure film, wherein the thicknesses of the layer A and the layer C are both 100 microns.

And then placing the laminated material in a vacuum film pressing machine, laminating for 5min at the temperature of 200 ℃ under the pressure of 18MPa, simultaneously starting a vacuum pump to vacuumize the system to remove bubbles contained in the system, and naturally cooling to room temperature after hot pressing is finished to obtain the high-strength backboard D3.

Comparative example No. four

A preparation method of a back sheet for a solar cell is the same as that of the first example, the previous preparation steps are the same as that of the first example, only a lamination step is not carried out, and an A layer and a C layer are directly subjected to melt extrusion and cast on two sides of a PET film to obtain an A/B/C three-layer structure film. A high strength backsheet D4 was obtained.

Some of the properties of the back sheets in the examples and comparative examples were tested and are detailed in the following table:

in the above table: s1 to S6 represent examples one to six, and D1 to D2 represent comparative examples one to four.

From the above table, S1 to S3 are different B layer thicknesses, which compared to D1 and D2 indicate that B layer thicknesses cannot be too small, and when B layer thicknesses are less than 20 μm, the backsheet is prone to wrinkling during aging tests; when the thickness of the second B layer is too large, problems such as poor interlayer peeling, poor low-temperature impact strength, and the like may occur.

S1, S4 and S5 are different lamination processes, which show that the lamination effect is better under high pressure for a short time, and the lamination time is too long, so that the back plate is not smooth.

S1 and S6 are different B layer materials, PET and PA6 can meet the requirements, and in comparison, PA6 is better in rigidity and elastic modulus, but in the low-temperature environment of PET, the composite material prepared by taking PET as the raw material of the B layer is higher in impact strength and cheaper.

D3 shows that the B layer is not present, the elastic modulus is poor, the water vapor permeability is poor, and the interlayer stripping force is poor, so that the requirements of the back sheet can not be met at all. D4 is the case without lamination, with very poor interlaminar peel and poor resistance to aging. Compared with the comparative example, the embodiment of the invention has better interlaminar peeling force, good mechanical property, high mechanical strength, and good low-temperature impact strength and toughness.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.