CN103066141A - Modified polypropylene resin composition and solar energy rear panel made of the same - Google Patents

Abstract

The invention discloses a solar backboard and a preparation method thereof. It includes an inner surface layer, a core layer and an outer surface layer from the inside to the outside. In terms of mass ratio, inner surface layer: core layer: outer layer = 10~20: 20~40: 40~60; the inner and outer layers are made of polyamide resin, fillers and additives; the core layer is made of a modified polypropylene resin composition; the modified polypropylene resin composition includes the following components : 100 parts of polypropylene resin, 5~50 parts of grafted polyethylene, 0~2.5 parts of additive, 0~100 parts of filler. The present invention simultaneously develops a new modified polypropylene resin composition for solar backsheets, and the obtained final product has excellent low-temperature impact resistance and aging resistance, especially moisture and heat aging resistance. The prepared solar backsheet has better water absorption rate, water vapor transmission rate, interlayer peeling and excellent electrical insulation than other backsheets, and meets the shrinkage rate, hot air aging and insulation properties required by the solar backsheet, and can be used for Manufacture of solar modules.

Description

A kind of modified polypropylene resin composition and the solar energy backboard made of it

technical field

The invention relates to a solar cell module polymer back sheet, in particular to a modified polypropylene resin solar back sheet and a preparation method thereof, belonging to the technical field of solar cell module manufacturing.

Background technique

Solar energy is the most abundant renewable energy resource, with unique advantages and huge potential for development and utilization. Solar power generation is a new technology in the way of solar energy utilization. The solar photovoltaic system is composed of solar battery packs, solar controllers, batteries, etc. The solar battery module is the core part of the solar power generation system, and the solar backplane is the structural packaging material of the solar battery module, which plays an important role in prolonging the service life of the solar battery. It plays a very important role and is an indispensable part of the solar cell module. The material for the preparation of the back sheet should have reliable insulation, water resistance, mechanical properties, UV aging resistance, and humidity and heat aging resistance.

At present, the main backsheets used at home and abroad are all multi-layer composite structures, all of which use polyester film (BOPET) as the base film and laminated with fluorine-containing materials such as polyvinyl fluoride film (PVF), polyvinylidene fluoride film ( PVDF) or coated with fluorocarbon resin (FEVE), etc., the price is more expensive, the production process is complicated, the electrical insulation and adhesion are poor, and it is easy to embrittle. From the point of view of the material of the backboard, the existing backplanes are generally based on polyester film (BOPET), and some researchers have improved the polyester film. Japanese Patent Application Publication No. 2007-007885, Japan Patent Publication No. 2006-306910 proposes a technical solution for using a polyester film containing 2,6-naphthalene dicarboxylic acid as a solar backsheet material, and a new type of rutile-type oxidation film is disclosed in the Chinese invention patent application CN102365172A. The laminated polyester film of titanium particles, but its adhesion with the adjacent EVA film cannot be guaranteed, and due to the structural characteristics of the material, it is difficult for polyester resin to overcome the high water absorption rate and poor moisture and heat aging resistance (brittleness) Defects, it is difficult to meet the performance requirements of solar backplanes.

Polypropylene resin has high strength, high heat resistance, high wear resistance, excellent electrical insulation, stress crack resistance and low creep, low water vapor transmission rate and excellent dielectric properties, and due to Propylene has no polar functional groups at the end of its molecular chain, so its water absorption rate is extremely low, which can meet the aging resistance performance requirements of solar cell modules, and is expected to become an important backsheet material. However, its cold resistance is poor, and it is brittle at low temperature. If it is directly used as a solar backplane substrate material, it cannot meet its low temperature impact resistance.

Therefore, to develop a resin composition with low water absorption, low embrittlement temperature and high insulation, and to prepare a resin composition with excellent moisture and heat aging resistance, adhesiveness and mechanical properties, which is suitable for industrial solar back panels. Is necessary.

Contents of the invention

The object of the present invention is to provide a solar back sheet and its preparation method, the back sheet has interlayer peel strength, excellent moisture and heat aging resistance, adhesiveness and mechanical insulation performance, and is suitable for the application of solar cell modules.

In order to achieve the above object, the technical solution adopted by the present invention is: a solar backboard, which includes an inner surface layer, a core layer and an outer layer from the inside to the outside, and the mass ratio of the inner surface layer, the core layer and the outer layer is 10-20 : 20~40: 40~60;

Wherein, the inner surface layer is made of polyamide resin, fillers and additives; the additives are selected from one or more of antioxidants, ultraviolet absorbers and light stabilizers;

The outer layer is made of polyamide resin, fillers and additives; the additives are selected from one or more of antioxidants, ultraviolet absorbers and light stabilizers;

The core layer is made of modified polypropylene resin composition;

The modified polypropylene resin composition, in parts by mass, includes the following components:

Polypropylene resin 100 parts

Grafted polyethylene 5-50 parts

Filler 0～100 parts

Additives 0～2.5 parts

The polypropylene resin is a homopolypropylene resin, a copolymerized polypropylene resin or a mixture of the two, the DSC melting point of the polypropylene resin is 160-168°C, and the melt flow rate is 1-2 g/10min;

The grafted polyethylene is prepared by grafting reaction from the following components:

Polyethylene resin 100 parts

Grafting agent 0.5～2.0 parts

Initiator 0.03～0.2 parts

The polyethylene resin is a homopolyethylene resin, a copolymerized polyethylene resin or a mixture of the two, the DSC melting point of the polyethylene resin is 120-135°C, and the melt flow rate is 1-2 g/10min.

In the above technical solution, the grafting agent is acrylic acid, acrylate ester, maleic acid, maleic anhydride or methine succinic acid.

In the above technical solution, the initiator is di-tert-butyl peroxide (DTBP) or dicumyl peroxide (DCP).

In the above technical solution, the filler is glass fiber, carbon fiber, talcum powder, mica, wollastonite or titanium dioxide.

The preparation of the above-mentioned solar backboard comprises the following steps:

(1) Mix polyethylene resin, grafting agent and initiator uniformly according to the described proportion, and process through screw melt extrusion to prepare grafted polyethylene;

(2) Add polypropylene resin, fillers and additives to the above-mentioned grafted polyethylene according to the proportion and mix them uniformly, and melt process with a screw to obtain the modified polypropylene resin composition;

(3) According to the ratio, the materials for preparing the inner surface layer, core layer and outer layer are respectively added to the A screw, B screw and C screw of the three-layer co-extrusion sheet unit, and melted and extruded in the screw extruder at the same time. Casting, cooling, pulling, and coiling can obtain the solar backsheet.

In the above preparation method, the reaction extrusion temperature of the screw melt extrusion processing in the step (3) is 180~240°C, the screw speed is controlled at 95~105 rpm, and the residence time of the material in the screw is 2-2. 4 minutes.

The invention also claims a modified polypropylene resin composition and a preparation method thereof.

The technical solution adopted is that a modified polypropylene resin composition, in parts by mass, includes the following components:

Polypropylene resin 100 parts

Grafted polyethylene 5-50 parts

Filler 0～100 parts

Additives 0～2.5 parts

The polypropylene resin is a homopolypropylene resin, a copolymerized polypropylene resin or a mixture of the two, the DSC melting point of the polypropylene resin is 160-168°C, and the melt flow rate is 1-2 g/10min;

The grafted polyethylene is prepared by grafting reaction from the following components:

Polyethylene resin 100 parts

Grafting agent 0.5～2.0 parts

Initiator 0.03～0.2 parts

The polyethylene resin is a homopolyethylene resin, a copolymerized polyethylene resin or a mixture of the two, the DSC melting point of the polyethylene resin is 120-135°C, and the melt flow rate is 1-2 g/10min.

In the above technical solution, the grafting agent is acrylic acid, acrylate ester, maleic acid, maleic anhydride or methine succinic acid.

In the above technical solution, the initiator is di-tert-butyl peroxide (DTBP) or dicumyl peroxide (DCP).

In the above technical solution, the filler is glass fiber, carbon fiber, talcum powder, mica, wollastonite or titanium dioxide.

The preparation method of above-mentioned modified polypropylene resin composition, comprises the steps:

(1) Mix polyethylene resin, grafting agent and initiator uniformly according to the proportion, and process through screw melt extrusion to prepare grafted polyethylene;

(2) Add the remaining components into the above-mentioned grafted polyethylene according to the proportion and mix them evenly, and melt process with a screw to obtain the resin composition.

In the above preparation method, the reaction extrusion temperature of the screw melt extrusion processing in the step (1) is 160~220°C; the screw speed is controlled at 95~105 rpm; the screw melt extrusion process in the step (2) The reaction extrusion temperature of extrusion processing is 180~240°C; the screw speed is controlled at 95~105 rpm.

The principle of the present invention: the polypropylene/polyethylene alloy designed and manufactured by the present invention is based on the latest theory of polymer alloying, that is, the theory of polymer self-solubilization. Due to the introduction of polymer crosslinking elements, the product can obtain excellent low temperature impact resistance. At the same time, aging resistance, especially high temperature, humidity and heat aging resistance, is also obtained. One of the reasons why the present invention uses polypropylene or polypropylene copolymer or its blend with a melting point (DSC) greater than 150°C as the main material of the present invention is that it can meet the processing requirements of solar panels. Due to the introduction of the grafting agent, part of the polyethylene is cross-linked to form a rubber-like cross-linked network structure to toughen the polypropylene, so that it can obtain excellent low-temperature impact resistance and high-temperature humidity-heat aging resistance. Through the test (test standard ASTM D6110), its Charpy notched impact (-20°C) can reach 15 KJ/m ² , which is much higher than the 2.55 KJ/m ² of ordinary polypropylene materials, so it can be used as a solar backplane Substrate. In addition, the low-temperature embrittlement temperature of the resin composition of the present invention is lower than -40°C, and the low-temperature embrittlement temperature of block copolymerized polypropylene without toughening modification is only -30°C, adding linear low-density polyethylene to the block The low-temperature embrittlement temperature of the copolymerized polypropylene blended modified resin composition can only reach -20°C.

The additives used in the present invention mainly include antioxidants, ultraviolet absorbers and light stabilizers.

Antioxidants can effectively inhibit the thermo-oxidative aging of polymers. The present invention has no particular limitation on the type of antioxidant. Antioxidants such as hindered phenol type, phosphite type and thioester type can be used as antioxidants of the present invention, and preferred antioxidants are tetrakis[?-(3',5'-di-tert-butyl-4' -Hydroxyphenyl)propionate]pentaerythritol and tris(2,4-di-tert-butylphenyl)phosphite.

The present invention has no particular limitation on the types of the ultraviolet light absorber and light stabilizer. A preferred UV absorber is 2-hydroxy-4-n-octyloxybenzophenone and a preferred light stabilizer is bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacic acid ester. Preferably, the light stabilizer is used together with the UV absorber, which can achieve the best effect that cannot be achieved by using the UV absorber alone, effectively preventing the yellowing of the material and retarding the loss of physical properties, and inhibiting or weakening photodegradation function to improve light aging resistance.

In the present invention, the inner surface layer is in contact with the EVA adhesive film in the solar battery module, and the outer surface layer is located outside the solar battery module. The polyamide resin selected for the inner and outer layers is a polycondensate of repeated amide structural units (-RCONH-) as the main chain of the polymer, which has high tensile strength, impact strength, excellent wear resistance and self-lubricating properties , and has good adhesion with EVA (ethylene vinyl acetate copolymer) film as packaging material and silica gel as filling and sealing.

In addition, the present invention uses a polar monomer as a grafting agent to undergo a grafting reaction with polyethylene under the action of an initiator. Grafted polyethylene not only has good compatibility with polypropylene resin, but also has good adhesion with adjacent polyamide resin, and maintains good interlayer peeling force between the three layers of materials.

Due to the adoption of the above-mentioned technical solution, compared with the prior art, the present invention has the following advantages:

1. The present invention develops a new resin composition for solar backsheets, which uses polypropylene resin as the main body, and grafts polyethylene toughening agent with grafting agent for toughening, and the obtained final product has excellent low temperature resistance In addition to impact resistance, it also has aging resistance, especially damp heat aging resistance, low saturated water absorption, low water vapor transmission rate and excellent electrical insulation, and can be used to manufacture solar back panels.

2. The solar back sheet prepared by the modified polypropylene resin composition disclosed in the present invention not only has excellent interlayer peeling force, but also has the performance of high temperature, humidity and heat aging resistance, and has good adhesion with EVA layer and silica gel, and can be used for the manufacture of solar cell modules.

3. The preparation method of the invention is simple and easy to implement, has low cost and is suitable for popularization and application.

Detailed ways

The present invention will be further described below in conjunction with embodiment:

Embodiment one:

A modified polypropylene resin composition, its preparation method is as follows:

(1) Preparation of grafted polyethylene PE-MA

100 parts (parts by mass) of LLDPE7042 (Beijing Yanshan Petrochemical Company), 1 part of maleic anhydride (chemical reagent, analytical grade), and 0.05 parts of DCP initiator (Tianjin Aksu Company) were measured and added to the mixer for mixing and homogenization. After homogenizing for two hours, put it into a twin-screw extruder for melt extrusion and granulation; cool and granulate to obtain granular grafted polyethylene PE-MA, and its melt flow rate at 190°C/2.16kg is 0.5g/10min. The diameter of the screw is 75mm, the aspect ratio is 33, the temperature of the screw is controlled at 160-220°C, the rotational speed of the screw is controlled at 100 rpm, and the residence time of the material in the screw is 2-4 minutes.

The LLDPE7042 (Beijing Yanshan Petrochemical Company) is a linear low-density polyethylene with a DSC melting point of 125°C, a melt flow rate of 2g/10min (190°C, 2.16 kg), a number average molecular weight of 17,000, a weight average molecular weight of 100,000, and a tensile Strength 12MPa, elongation at break 500%;

(2) Preparation of modified polypropylene resin composition: 67 parts of polypropylene K8303 (Beijing Yanshan Petrochemical Company), 33 parts of grafted polyethylene PE-MA, 20 parts of rutile titanium dioxide R960 (U.S. DuPont Company), 0.2 Parts of antioxidant tetrakis[?-(3',5'-di-tert-butyl-4'-hydroxyphenyl) propionate] pentaerythritol ester (Beijing Institute of Addition Auxiliaries, KY1010), 0.2 part of UV absorber 2-Hydroxy-4-n-octyloxybenzophenone (Beijing Institute of Addition Auxiliaries, GW531), 0.1 parts of light stabilizer bis(2,2,6,6-tetramethyl-4-piperidinyl ) sebacate (Beijing Institute of Addition Auxiliaries, GW480) were measured separately and mixed evenly; put into a twin-screw extruder for melt extrusion (the twin-screw adopts exhaust screw, the screw diameter is 75 mm, and the length-to-diameter ratio 33. The screw temperature is controlled at 180-240°C, the screw speed is controlled at 100 rpm, and the residence time of the material in the screw is 2-4 minutes); the material is cooled, granulated and dried to become the finished product S1.

The polypropylene K8303 is a block copolymer polypropylene product produced by Beijing Yanshan Petrochemical Company, with a DSC melting temperature of 163°C, a melt flow rate of 2g/10min (230°C, 2.16 kg), a number average molecular weight of 29,000, and a weight average molecular weight of 38,000 , the tensile yield strength is 22MPa, the elongation at break is 22%, the Rockwell hardness is 75R, the Izod impact strength is 480J/M at 23°C, and 40J/M at -20°C.

Embodiment two:

A modified polypropylene resin composition, its preparation method is as follows:

(1) Preparation of grafted polyethylene PE-MA: see Example 1

(2) Preparation of modified polypropylene resin composition: 75 parts of block copolymerized polypropylene K8303, 25 parts of grafted polyethylene PE-MA, 50 parts of rutile titanium dioxide R960, 0.25 parts of antioxidant tetra[?- (3',5'-di-tert-butyl-4'-hydroxyphenyl) propionate] pentaerythritol ester, 0.2 part of UV absorber 2-hydroxy-4-n-octyloxybenzophenone, 0.1 part of light stabilizer The agent bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate is mixed evenly according to the metering ratio, and then put into the twin-screw extruder for melt extrusion (the twin-screw adopts the exhaust screw, The diameter of the screw is 75 mm, the ratio of length to diameter is 33, the temperature of the screw is controlled at 180-240 ° C, the speed of the screw is controlled at 100 rpm, and the residence time of the material in the screw is 2-4 minutes); the material is cooled, granulated and dried That is the finished product S2.

Embodiment three:

A modified polypropylene resin composition, its preparation method is as follows:

(1) Preparation of grafted polyethylene PE-MA: see Example 1

(2) Preparation of modified polypropylene resin composition: 96 parts of polypropylene 1300 and 4 parts of grafted polyethylene PE-MA, 40 parts of rutile titanium dioxide R960, 0.2 parts of antioxidant tetrakis[?-(3' , 5'-di-tert-butyl-4'-hydroxyphenyl) propionate] pentaerythritol ester, 0.25 parts of UV absorber 2-hydroxy-4-n-octyloxybenzophenone, 0.15 parts of light stabilizer bis( 2,2,6,6-tetramethyl-4-piperidinyl) sebacate is mixed evenly and put into a twin-screw extruder for melt extrusion (the twin-screw adopts an exhaust screw, and the diameter of the screw is 75 mm. The aspect ratio is 33, the screw temperature is controlled at 180-240°C, the screw speed is controlled at 100 rpm, and the residence time of the material in the screw is 2-4 minutes); the material is cooled, granulated and dried to become the finished product S3.

Embodiment four:

A modified polyamide resin composition, its preparation method is as follows:

(1) Preparation of grafted polyethylene PE-MA: see Example 1

(2) Preparation of modified polypropylene resin composition: 50 parts of block copolymerized polypropylene K8303, 50 parts of grafted polyethylene PE-MA, 60 parts of rutile titanium dioxide R960, 0.3 parts of antioxidant tetra[?- (3',5'-di-tert-butyl-4'-hydroxyphenyl) propionate] pentaerythritol ester, 0.25 parts of UV absorber 2-hydroxy-4-n-octyloxybenzophenone, 0.15 parts of light stabilizer The agent bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate is mixed evenly and put into the twin-screw extruder for melt extrusion (the twin-screw adopts exhaust screw, the screw diameter 75mm, length-to-diameter ratio 33, screw temperature controlled at 180-240°C, screw speed controlled at 100 rpm, residence time of the material in the screw is 2-4 minutes); the material is cooled, pelletized and dried Finished product S4.

Embodiment five:

A co-extruded polypropylene solar back sheet, the preparation method of which is as follows:

(1) Add 100 parts of polyhexamethylene dodecamide (PA612) into the desiccator, dry at 80°C for 4 hours, put it into a high mixer, add 20 parts of rutile titanium dioxide R960, 0.2 parts of antioxidant four [?-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionic acid]pentaerythritol ester, 0.2 parts of UV absorber 2-hydroxy-4-n-octyloxybenzophenone, 0.1 One part of light stabilizer bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, stirred for 30 minutes, the speed was 600 rpm, and the materials were mixed evenly; then the above materials were put into three The A screw of the layer co-extruded sheet unit has a screw diameter of 60 mm and a ratio of length to diameter of 33.

(2) Put the finished product S1 prepared in Example 1 into the B screw of the three-layer co-extrusion sheet unit, the screw diameter is 90 mm, and the aspect ratio is 33.

(3) Add 100 parts of polyhexamethylene dodecamide (PA612) into the desiccator, dry at 80°C for 4 hours, put it into a high mixer, add 20 parts of rutile titanium dioxide R960, 0.2 parts of antioxidant IV [?-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionic acid]pentaerythritol ester, 0.2 parts of UV absorber 2-hydroxy-4-n-octyloxybenzophenone, 0.1 One part of light stabilizer bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, stirred for 30 minutes, the speed was 600 rpm, and the materials were mixed evenly; then the above materials were put into three The C screw of the layer co-extruded sheet unit has a screw diameter of 60 mm and an aspect ratio of 33.

(4) Melt and extrude the three materials in the screw extruder at the same time, the screw temperature is controlled at 180-240°C, the screw speed is controlled at 100 rpm, and the residence time of the materials in the screw is 2-4 minutes. The inner surface layer, core layer and outer layer are distributed in the distributor with a weight ratio of 10/40/50, and then enter the T-shaped die (die width 1200mm), after cooling, pulling, coiling and other processes The finished product S5 was obtained, the cooling water temperature of the three rolls was 60-70°C, the pulling speed was 3-4 m/min, the product thickness was 0.33mm, and the width was 1000mm. The test results are shown in Table 1.

Embodiment six:

A co-extruded polypropylene solar back sheet, the preparation method of which is as follows:

(1) Add 100 parts of polysebacyldecanediamine (PA1010) into the desiccator, dry at 80°C for 4 hours, put it into a high mixer, add 20 parts of rutile titanium dioxide R960, 0.2 parts of antioxidant four [? -(3',5'-di-tert-butyl-4'-hydroxyphenyl) propionate] pentaerythritol ester, 0.2 parts of UV absorber 2-hydroxy-4-n-octyloxybenzophenone, 0.1 parts of light Stabilizer bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, stir for 30 minutes, rotate at 600 rpm, mix the materials evenly; then put the above materials into three layers The A screw of the extruded sheet unit has a screw diameter of 60 mm and a length-to-diameter ratio of 33.

(2) Put the finished product S2 prepared in Example 2 into the B screw of the three-layer co-extrusion sheet unit, the screw diameter is 90 mm, and the aspect ratio is 33.

(3) Add 100 parts of polysebacyldecanediamine (PA1010) into the dryer, dry at 80°C for 4 hours, put the material into a high mixer, add 20 parts of rutile titanium dioxide R960, 0.2 parts of antioxidant IV [?-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionic acid]pentaerythritol ester, 0.2 parts of UV absorber 2-hydroxy-4-n-octyloxybenzophenone, 0.1 One part of light stabilizer bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, stirred for 30 minutes, the speed was 600 rpm, and the materials were mixed evenly; then the above materials were put into three The C screw of the layer co-extruded sheet unit has a screw diameter of 60 mm and an aspect ratio of 33.

(4) Melt and extrude the three materials in the screw extruder at the same time, the screw temperature is controlled at 180-240°C, the screw speed is controlled at 100 rpm, and the residence time of the materials in the screw is 2-4 minutes. The inner layer, core layer and outer layer are distributed in the distributor with a ratio of 20/40/40, and then enter the T-shaped die head with a width of 1200mm, and the finished product is obtained through cooling, pulling, coiling and other processes S6, the cooling water temperature of the three rolls is 60-70°C, and the pulling speed is 3-4 m/min. The thickness of the product is 0.33mm and the width is 1000mm. The test results are shown in Table 1.

Embodiment seven:

A co-extruded polypropylene solar back sheet, the preparation method of which is as follows:

(1) Add 100 parts of polysebacyldecanediamine (PA1010) into the desiccator, dry at 80°C for 4 hours, put it into a high mixer, add 20 parts of rutile titanium dioxide R960, 0.2 parts of antioxidant four [? -(3',5'-di-tert-butyl-4'-hydroxyphenyl) propionate] pentaerythritol ester, 0.2 parts of UV absorber 2-hydroxy-4-n-octyloxybenzophenone, 0.1 parts of light Stabilizer bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, stir for 30 minutes, rotate at 600 rpm, mix the materials evenly; then put the above materials into three layers The A screw of the extruded sheet unit has a screw diameter of 60 mm and a length-to-diameter ratio of 33.

(2) Put the finished product S3 prepared in Example 3 into the B screw of the three-layer co-extrusion sheet unit, the screw diameter is 90 mm, and the aspect ratio is 33.

(3) Add 100 parts of polysebacyldecanediamine (PA1010) into the desiccator, dry at 80°C for 4 hours, put it into a high mixer, add 20 parts of rutile titanium dioxide R960, 0.2 parts of antioxidant four [? -(3',5'-di-tert-butyl-4'-hydroxyphenyl) propionate] pentaerythritol ester, 0.2 parts of UV absorber 2-hydroxy-4-n-octyloxybenzophenone, 0.1 parts of light Stabilizer bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, stir for 30 minutes, rotate at 600 rpm, mix the materials evenly; then put the above materials into three layers The C screw of the extrusion sheet unit has a screw diameter of 60 mm and an aspect ratio of 33.

(4) Melt and extrude the three materials in the screw extruder at the same time, the screw temperature is controlled at 180-240°C, the screw speed is controlled at 100 rpm, and the residence time of the materials in the screw is 2-4 minutes. The inner layer, core layer and outer layer are distributed in the distributor with a ratio of 20/30/50, and then enter the T-shaped die head with a width of 1200mm, and the finished product is obtained through cooling, pulling, coiling and other processes S7, the cooling water temperature of the three rolls is 60-70°C, and the pulling speed is 3-4 m/min. The thickness of the product is 0.33mm and the width is 1000mm. The test results are shown in Table 1.

Embodiment eight:

A co-extruded polypropylene solar back sheet, the preparation method of which is as follows:

(1) Add 100 parts of polysebacyldecanediamine (PA1010) into the desiccator, dry at 80°C for 4 hours, put it into a high mixer, add 20 parts of rutile titanium dioxide R960, 0.2 parts of antioxidant four [? -(3',5'-di-tert-butyl-4'-hydroxyphenyl) propionate] pentaerythritol ester, 0.2 parts of UV absorber 2-hydroxy-4-n-octyloxybenzophenone, 0.1 parts of light Stabilizer bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, stir for 30 minutes, rotate at 600 rpm, mix the materials evenly; then put the above materials into three layers The A screw of the extruded sheet unit has a screw diameter of 60 mm and a length-to-diameter ratio of 33.

(2) Put the finished product S4 prepared in Example 4 into the B screw of the three-layer co-extrusion sheet material unit, the screw diameter is 90 mm, and the aspect ratio is 33.

(3) Add 100 parts of polydecanediamide sebacamide (PA1010) into the dryer, dry at 80°C for 4 hours, and test the moisture content (90°C, 3 hours) to be less than 0.1%. Then put the material into a high mixer, add 20 parts of rutile titanium dioxide R960, 0.2 parts of antioxidant tetrakis[?-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionic acid]pentaerythritol Esters, 0.2 parts of UV absorber 2-hydroxy-4-n-octyloxybenzophenone, 0.1 parts of light stabilizer bis(2,2,6,6-tetramethyl-4-piperidinyl) decane Ester, stirred for 30 minutes, the rotating speed was 600 rpm, and the materials were mixed evenly. Then put the above materials into the C screw of the three-layer co-extrusion sheet material unit, the diameter of the screw is 60 mm, and the aspect ratio is 33.

(4) Melt and extrude the three materials in the screw extruder at the same time, the screw temperature is controlled at 180-240°C, the screw speed is controlled at 100 rpm, and the residence time of the materials in the screw is 2-4 minutes. The inner layer, core layer and outer layer are distributed in the distributor with a ratio of 20/40/40, and then enter the T-shaped die head with a width of 1200mm, and the finished product is obtained through cooling, pulling, coiling and other processes S8, the cooling water temperature of the three rolls is 60-70°C, and the pulling speed is 3-4 m/min. The thickness of the product is 0.33mm and the width is 1000mm. The test results are shown in Table 1.

Comparative example one:

It is a TPT type backsheet (Kunshan Taihong Company), the product structure is PVF/PET/PVF, the thickness is 0.33mm, and it is recorded as B1. The test results are shown in Table 1.

Comparative example two:

It is a TPE type backsheet (Toyo Aluminum Co., Ltd., Japan), the product structure is PVDF/PET/PE, the thickness is 0.33mm, and it is recorded as B2. The test results are shown in Table 1.

Comparative example three:

It is a FEVE type backsheet (Suzhou Zhonglai Company), the product structure is FEVE/PET/FEVE, the thickness is 0.30mm, and it is recorded as B3. The test results are shown in Table 1.

Table 1 The characterization of the backplane in the embodiment and the comparative example

It can be seen from the results in Table 1 that the three-layer co-extruded solar backsheet of the present invention not only has the shrinkage rate, hot air aging resistance, and insulation performance that meet the requirements of the solar backsheet, but also has better water absorption than other backsheets, The water vapor transmission rate, interlayer peeling and moisture-heat aging resistance properties can be used to prepare solar cell modules.

The characterization method in above-mentioned each embodiment and comparative example adopts following standard:

Melt flow rate ASTM D1238 Standard test method for melt flow rate of thermoplastics;

Tensile Strength ASTM D638 Standard Test Method for Tensile Properties of Plastics;

Elongation at Break ASTM D638 Standard Test Method for Tensile Properties of Plastics;

Bending strength ASTM D790 unreinforced and reinforced plastic bending performance test;

Charpy notched impact strength ASTM D6110 Plastic notched specimen impact resistance test method;

Notched Izod Impact Strength ASTM D256 Test Method for Impact Resistance of Plastics and Electrical Insulation Materials;

Shrinkage GB/T 13541 Electrical plastic film test method

Saturated water absorption GB/T 1034 Plastic water absorption test method

Water vapor transmission rate GB/T 21529 Determination of water vapor transmission rate of plastic films and sheets

Thermal Oxygen Aging GB/T7141 Plastic Thermal Aging Test Method

Damp heat aging GB/T 2423.40 Environmental testing for electrical and electronic products Part 2: Test method Test Cx: Unsaturated high-pressure steam constant damp heat

Volume resistivity GB/T 1410 Test method for volume resistivity and surface resistivity of solid insulating materials.

Claims (10)

1. A solar backboard, comprising an inner surface layer, a core layer and an outer layer from the inside to the outside, characterized in that the mass ratio of the inner surface layer, the core layer and the outer layer is 10～20:20～40:40～ 60; Wherein, the inner surface layer is made of polyamide resin, fillers and additives; the additives are selected from one or more of antioxidants, ultraviolet absorbers and light stabilizers; The outer layer is made of polyamide resin, fillers and additives; the additives are selected from one or more of antioxidants, ultraviolet absorbers and light stabilizers; The core layer is made of modified polypropylene resin composition; The modified polypropylene resin composition, in parts by mass, includes the following components: Polypropylene resin 100 parts Grafted polyethylene 5-50 parts Filler 0～100 parts Additives 0～2.5 parts The additive is selected from one or more of antioxidants, ultraviolet absorbers and light stabilizers; The polypropylene resin is a homopolypropylene resin, a copolymerized polypropylene resin or a mixture of the two, the DSC melting point of the polypropylene resin is 160-168°C, and the melt flow rate is 1-2 g/10min; The grafted polyethylene is prepared by grafting reaction from the following components: Polyethylene resin 100 parts Grafting agent 0.5～2.0 parts Initiator 0.03～0.2 parts The polyethylene resin is a homopolyethylene resin, a copolymerized polyethylene resin or a mixture of the two. The DSC melting point of the polyethylene resin is 120-135°C, and the melt flow rate is 1-2 g/10min. 2 . The solar back sheet according to claim 1 , wherein the grafting agent is acrylic acid, acrylate ester, maleic acid, maleic anhydride or methine succinic acid. 3. The solar back sheet according to claim 1, characterized in that: the initiator is di-tert-butyl peroxide or dicumyl peroxide. 4. The solar backsheet according to claim 1, wherein the filler is glass fiber, carbon fiber, talcum powder, mica, wollastonite or titanium dioxide. 5. A method for preparing a solar back panel as claimed in claim 1, comprising the steps of: (1) Polyethylene resin, grafting agent and initiator are mixed homogeneously by the proportioning described in claim 1, process through screw melt extrusion, prepare grafted polyethylene; (2) Add polypropylene resin, fillers and additives to the above-mentioned grafted polyethylene according to the proportion and mix them uniformly, and melt process with a screw to obtain the modified polypropylene resin composition; (3) According to the ratio, the materials for preparing the inner surface layer, core layer and outer layer are respectively added to the A screw, B screw and C screw of the three-layer co-extrusion sheet unit, and melted and extruded in the screw extruder at the same time. Casting, cooling, pulling, and coiling can obtain the solar backsheet. 6. A modified polypropylene resin composition, characterized in that, in parts by mass, comprising the following components: Polypropylene resin 100 parts Grafted polyethylene 5-50 parts Filler 0～100 parts Additives 0～2.5 parts The polypropylene resin is a homopolypropylene resin, a copolymerized polypropylene resin or a mixture of the two, the DSC melting point of the polypropylene resin is 160-168°C, and the melt flow rate is 1-2 g/10min; The grafted polyethylene is prepared by grafting reaction from the following components: Polyethylene resin 100 parts Grafting agent 0.5～2.0 parts Initiator 0.03～0.2 parts The polyethylene resin is a homopolyethylene resin, a copolymerized polyethylene resin or a mixture of the two. The DSC melting point of the polyethylene resin is 120-135°C, and the melt flow rate is 1-2 g/10min. 7. The resin composition according to claim 6, characterized in that: the grafting agent is acrylic acid, acrylate ester, maleic acid, maleic anhydride or methine succinic acid. 8. The resin composition according to claim 6, characterized in that: the initiator is di-tert-butyl peroxide or dicumyl peroxide. 9. The resin composition according to claim 6, wherein the filler is glass fiber, carbon fiber, talcum powder, mica, wollastonite or titanium dioxide. 10. a preparation method of the resin composition as claimed in claim 6, is characterized in that, comprises the steps: (1) Polyethylene resin, grafting agent and initiator are mixed homogeneously by the proportioning described in claim 6, process through screw melt extrusion, prepare grafted polyethylene; (2) Add the remaining components to the above-mentioned grafted polyethylene according to the proportion and mix them uniformly, and melt process with a screw to obtain the modified polypropylene resin composition.