阅读说明：本技术 一种透明背板膜用聚烯烃膜及其制备方法 (Polyolefin film for transparent back plate film and preparation method thereof ) 是由 朱业玲 于 2019-12-02 设计创作，主要内容包括：本发明提供一种透明背板膜用聚烯烃膜及其制备方法。所述聚烯烃膜包括依次层叠的复合层、芯层和热封层；所述复合层的材料包括：线性低密度聚乙烯60-78％、低密度聚乙烯20-38％、紫外吸收剂0.5-1％和光稳定剂0.5-1％；所述芯层的材料包括：线性低密度聚乙烯60-75％、低密度聚乙烯20-35％、紫外吸收剂2-6％和光稳定剂1-3％；所述热封层的材料按包括：线性低密度聚乙烯60-75％、低密度聚乙烯20-35％、紫外吸收剂1.5-3％和光稳定剂0.5-2％。所述聚烯烃膜具有很好的机械性能和加工性,还具有优异的抗紫外性、高透光性和绝缘性,与PET剥离强度高,与EVA的粘结强度好。(The invention provides a polyolefin film for a transparent back plate film and a preparation method thereof. The polyolefin film comprises a composite layer, a core layer and a heat sealing layer which are sequentially laminated; the material of the composite layer comprises: 60-78% of linear low-density polyethylene, 20-38% of low-density polyethylene, 0.5-1% of ultraviolet absorbent and 0.5-1% of light stabilizer; the material of the core layer comprises: 60-75% of linear low-density polyethylene, 20-35% of low-density polyethylene, 2-6% of ultraviolet absorbent and 1-3% of light stabilizer; the heat-sealing layer is made of materials comprising: 60-75% of linear low density polyethylene, 20-35% of low density polyethylene, 1.5-3% of ultraviolet absorbent and 0.5-2% of light stabilizer. The polyolefin film has good mechanical property and processability, excellent ultraviolet resistance, high light transmittance and insulativity, high peeling strength with PET and good bonding strength with EVA.)

1. The polyolefin film for the transparent back plate film is characterized by comprising a composite layer, a core layer and a heat sealing layer which are sequentially laminated;

the composite layer comprises the following materials in percentage by weight: 60-78% of linear low-density polyethylene, 20-38% of low-density polyethylene, 0.5-1% of ultraviolet absorbent and 0.5-1% of light stabilizer;

the core layer comprises the following materials in percentage by weight: 60-75% of linear low-density polyethylene, 20-35% of low-density polyethylene, 2-6% of ultraviolet absorbent and 1-3% of light stabilizer;

the heat sealing layer comprises the following materials in percentage by weight: 60-75% of linear low density polyethylene, 20-35% of low density polyethylene, 1.5-3% of ultraviolet absorbent and 0.5-2% of light stabilizer.

2. The polyolefin film for transparent backsheet film according to claim 1, wherein the polyolefin film has a thickness of 50 to 150 μm;

preferably, the thickness ratio of the composite layer to the core layer to the heat-sealing layer is 1 (2-3) to (1-1.5), and preferably 1 (2-3) to 1.

3. The polyolefin film for transparent backsheet film according to claim 1 or 2, wherein the melt index of linear low density polyethylene in the material of the composite layer is 1 to 5g/10 min;

preferably, the melt index of the low-density polyethylene in the material of the composite layer is 1-5g/10 min;

preferably, the ultraviolet absorbent in the material of the composite layer comprises any one of or a combination of at least two of a high molecular weight benzophenone-based absorbent or a benzotriazole-based absorbent;

preferably, the benzophenone-based absorber comprises any one of UV-531, UV-981 or UV-1009 or a combination of at least two thereof;

preferably, the benzotriazole-based absorber comprises any one or a combination of at least two of UV-326, UV327 or UV-360;

preferably, the light stabilizer in the material of the composite layer comprises UV3529 and/or light stabilizer 622;

preferably, the material of the composite layer further comprises an antioxidant;

preferably, the antioxidant comprises antioxidant 1076 and/or antioxidant 168;

preferably, the material of the composite layer further comprises a processing aid;

preferably, the processing aid comprises a PPA aid and/or a mouth-opening agent;

preferably, the opening agent is a silica opening agent;

preferably, the particle size of the silica opening agent is 4-5 μm;

preferably, the material of the composite layer comprises, in weight percent: 60-78% of linear low density polyethylene, 20-38% of low density polyethylene, 0.5-1% of ultraviolet absorber, 0.5-1% of light stabilizer, 0.5-1% of antioxidant and 0.5-2% of processing aid.

4. The polyolefin film for transparent backsheet film according to any one of claims 1 to 3, wherein the melt index of the linear low density polyethylene in the material of the core layer is 1 to 5g/10 min;

preferably, the melt index of the low density polyethylene in the material of the core layer is 1-5g/10 min;

preferably, the ultraviolet absorbent in the material of the core layer comprises any one of or a combination of at least two of a high molecular weight benzophenone-based absorbent or a benzotriazole-based absorbent;

preferably, the high molecular weight benzophenone-based absorber comprises any one of UV-531, UV-981 or UV-1009 or a combination of at least two thereof;

preferably, the benzotriazole-based absorber comprises any one or a combination of at least two of UV-326, UV327 or UV-360;

preferably, the light stabilizer in the material of the core layer comprises UV3529 and/or light stabilizer 622;

preferably, the material of the core layer further comprises an antioxidant;

preferably, the antioxidant comprises antioxidant 1076 and/or antioxidant 168;

preferably, the core layer comprises the following materials in percentage by weight: 60-75% of linear low density polyethylene, 20-35% of low density polyethylene, 2-6% of ultraviolet absorbent, 1-3% of light stabilizer and 0.5-1% of antioxidant.

5. The polyolefin film for transparent backsheet films according to any one of claims 1 to 4, wherein the linear low density polyethylene in the material of the heat-seal layer has a melt index of 1 to 5g/10 min;

preferably, the melt index of the low-density polyethylene in the material of the heat sealing layer is 1-5g/10 min;

preferably, the ultraviolet absorbent in the material of the heat sealing layer comprises any one of or a combination of at least two of a high molecular weight benzophenone-based absorbent or a benzotriazole-based absorbent;

preferably, the high molecular weight benzophenone-based absorber comprises any one of UV-531, UV-981 or UV-1009 or a combination of at least two of the above;

preferably, the benzotriazole-based absorber comprises any one of UV-326, UV327 or UV-360 or a combination of at least two thereof;

preferably, the light stabilizer comprises UV3529 and/or light stabilizer 622;

preferably, the material of the heat sealing layer further comprises an antioxidant;

preferably, the antioxidant comprises antioxidant 1076 and/or antioxidant 168;

preferably, the material of the heat sealing layer further comprises a processing aid;

preferably, the processing aid comprises a PPA aid and/or a mouth-opening agent

Preferably, the opening agent is a silica opening agent;

preferably, the particle size of the silica opening agent is 4-5 μm;

preferably, the material of the heat-sealing layer comprises the following components in percentage by weight: 60-75% of linear low density polyethylene, 20-35% of low density polyethylene, 1.5-3% of ultraviolet absorbent, 0.5-2% of light stabilizer, 0.5-1% of antioxidant and 0.5-2% of processing aid.

6. The method for producing a polyolefin film for a transparent backsheet film according to any one of claims 1 to 5, characterized by comprising the steps of:

(1) respectively mixing the materials of the composite layer, the core layer and the heat sealing layer to obtain a composite layer premix, a core layer premix and a heat sealing layer premix;

(2) respectively blending the composite layer premix, the core layer premix and the heat sealing layer premix obtained in the step (1) to obtain composite layer compound particles, core layer compound particles and heat sealing layer compound particles;

(3) and (3) carrying out melting plasticization, extrusion and sizing on the composite layer compound particles, the core layer compound particles and the heat sealing layer compound particles obtained in the step (2) to obtain the polyolefin film for the transparent back plate film.

7. The method of claim 6, wherein the mixing of step (1) is performed in a high-speed mixer;

preferably, the rotation speed of the high-speed mixer in the mixing in the step (1) is 500-1000 rpm.

8. The production method according to claim 6 or 7, wherein the blending of step (2) is carried out in a twin-screw extruder;

preferably, the temperature for the blending in step (2) is 150-250 ℃.

9. The production method according to any one of claims 6 to 8, wherein the melt plasticization of step (3) is performed in a multilayer coextrusion casting apparatus or a film blowing apparatus;

preferably, the temperature for melt plasticizing in the step (3) is 160-250 ℃;

preferably, the shaping in the step (3) is cooling shaping;

preferably, step (3) is followed by step (4): and carrying out corona treatment on the transparent back plate film by using a polyolefin film, and winding to obtain a finished product.

10. The method according to any one of claims 6 to 9, characterized in that it comprises the steps of:

(1) respectively putting the materials of the composite layer, the core layer and the heat sealing layer into a high-speed mixer with the speed of 500-1000rpm for uniform mixing to obtain a composite layer premix, a core layer premix and a heat sealing layer premix;

(2) respectively carrying out blending modification granulation on the composite layer premix, the core layer premix and the heat sealing layer premix obtained in the step (1) at the temperature of 150 ℃ and 250 ℃ by a double-screw extruder to obtain composite layer compound particles, core layer compound particles and heat sealing layer compound particles;

(3) melting and plasticizing the composite layer compound particles, the core layer compound particles and the heat sealing layer compound particles obtained in the step (2) in multilayer coextrusion casting equipment or film blowing equipment at the temperature of 160-250 ℃, extruding through a die head, and cooling and shaping to obtain the polyolefin film for the transparent back plate film;

(4) and (4) carrying out corona treatment on the transparent back plate film obtained in the step (3) by using a polyolefin film, and winding to obtain a finished product.

Technical Field

The invention belongs to the technical field of packaging composite materials, and particularly relates to a polyolefin film for a transparent back plate film and a preparation method thereof.

Background

With the rapid development of the photovoltaic power generation technology, in order to realize the flat-price network access of the photovoltaic power generation, the double-sided power generation battery is concerned, and the appearance of the transparent back plate leads the double-sided power generation technology to have a new application prospect. In addition to the electrical insulation, weather resistance and moisture resistance of conventional back sheets, the transparent back sheet also needs to have high light transmittance and excellent ultraviolet resistance. At present, composite back panels in the market occupy an important position, and most of the materials used for the contact surfaces of the composite back panels and ethylene-vinyl acetate copolymer (EVA) are polyolefin films, while the ultraviolet shielding function of transparent EVA is poor, so in order to protect polyethylene terephthalate (PET) in the middle layer of the composite back panels from being damaged by ultraviolet rays, it is urgently needed to improve the light transmittance and ultraviolet resistance of the polyolefin films except for fluorine films.

CN108682707A discloses a transparent back plate of solar photovoltaic cell module for double-sided power generation. The transparent back plate is composed of a weather-resistant layer, a first bonding layer, a substrate layer, a second bonding layer and a high-transmittance barrier layer from top to bottom in sequence, wherein the first bonding layer and the second bonding layer are one of polyurethane, acrylate or epoxy resin systems, the substrate layer is a transparent weather-resistant film, and the high-transmittance barrier layer is an annular polyolefin film. The transparent back plate belongs to a fluorine-free back plate, the weather resistance has a risk, and the ultraviolet resistance of the transparent back plate is to be improved.

CN110271254A discloses a polyolefin-based transparent photovoltaic back sheet, which comprises, in order from the cell side to the air side: transparent polyolefin inlayer, first glue layer, transparent PET substrate layer, second glue layer and transparent fluoropolymer layer of nai time. The weatherability, especially the ultraviolet resistance of the polypropylene-containing transparent back sheet is also to be further improved.

Therefore, the development of a polyolefin film for a transparent back sheet film having excellent uv resistance and high light transmittance is a major research in the art.

Disclosure of Invention

In view of the defects of the prior art, the invention aims to provide a polyolefin film for a transparent back plate film and a preparation method thereof, wherein the polyolefin film has excellent ultraviolet resistance, high light transmission and insulation, and the film has high peeling strength with PET and good bonding strength with EVA.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides a polyolefin film for a transparent backsheet film, the polyolefin film comprising a composite layer, a core layer and a heat-seal layer laminated in this order; the composite layer comprises the following materials in percentage by weight: 60-78% of linear low-density polyethylene, 20-38% of low-density polyethylene, 0.5-1% of ultraviolet absorbent and 0.5-1% of light stabilizer; the core layer comprises the following materials in percentage by weight: 60-75% of linear low-density polyethylene, 20-35% of low-density polyethylene, 2-6% of ultraviolet absorbent and 1-3% of light stabilizer; the heat sealing layer comprises the following materials in percentage by weight: 60-75% of linear low density polyethylene, 20-35% of low density polyethylene, 1.5-3% of ultraviolet absorbent and 0.5-2% of light stabilizer.

Wherein, the heat sealing layer needs to be bonded with EVA, the material needs to have good hot melting property, and the sealing needs to be easy; the core layer plays a supporting role on the film, and the stiffness of the film is improved; the composite layer is required to be compounded with PET, and has moderate surface tension and high compounding strength.

In the invention, the polyolefin film comprises a composite layer, a core layer and a heat sealing layer which are sequentially laminated, wherein the core layer is positioned between the composite layer and the heat sealing layer. The three layers of material each comprise linear low density polyethylene and low density polyethylene. Linear Low Density Polyethylene (LLDPE) is non-toxic, tasteless and odorless milky white particles, has higher softening temperature and melting temperature, and simultaneously has the advantages of high strength, good toughness, high rigidity, heat resistance and cold resistance, and also has good environmental stress crack resistance, impact strength and tear strength resistance. Low Density Polyethylene (LDPE), also known as high pressure low density polyethylene, has good flexibility, extensibility, electrical insulation, transparency, easy processability and a certain gas permeability. It has better chemical stability, alkali resistance and organic solvent resistance. The two polyethylene materials are mutually matched and have synergistic interaction, so that each layer has excellent mechanical property and processability.

In the invention, the ultraviolet absorbent is a high molecular weight ultraviolet absorbent, can strongly absorb ultraviolet rays with the wavelength of 280-380nm, and has stable chemical properties, extremely low volatility and good compatibility with polyolefin.

In the present invention, the light stabilizer is a high molecular weight light stabilizer, has low migration and volatility and good heat resistance, and effectively prevents degradation of the polyolefin material by light, heat and moisture.

In the invention, the ultraviolet absorber and the light stabilizer are used in a matching way, and have a synergistic effect. The yellowing of the material and the reduction of the mechanical property of the material are prevented, the aging resistance of the material is improved, in addition, the optical property of the material is not influenced, and simultaneously, the composite strength of the polyolefin material and PET and the heat sealing of EVA are not influenced.

In the material of the composite layer of the present invention, the linear low density polyethylene is 60 to 78% by weight, for example, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%.

In the material of the composite layer of the present invention, the low density polyethylene is 20 to 38% by weight, for example, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%.

In the material of the composite layer of the present invention, the weight percentage of the uv absorber is 0.5 to 1%, and may be, for example, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%.

In the material of the composite layer of the present invention, the light stabilizer may be 0.5 to 1% by weight, for example, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%.

In the material of the core layer of the present invention, the linear low density polyethylene is 60 to 75% by weight, for example, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%.

In the material of the core layer of the present invention, the weight percentage of the low density polyethylene is 20 to 35%, and may be, for example, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%.

In the material of the core layer of the present invention, the weight percentage of the uv absorber is 2-6%, for example, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%.

In the material of the core layer of the present invention, the light stabilizer is 1 to 3% by weight, and may be, for example, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.6%, 2.8%, 3%.

In the material of the heat-sealable layer of the present invention, the linear low density polyethylene is 60 to 75% by weight, for example 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%.

In the material of the heat-sealable layer of the present invention, the low-density polyethylene is 20 to 35% by weight, and may be, for example, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%.

In the material of the heat-seal layer of the present invention, the weight percentage of the ultraviolet absorber is 1.5 to 3%, and may be, for example, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%.

In the material of the heat-sealable layer of the present invention, the light stabilizer may be 0.5 to 2% by weight, for example, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%.

Preferably, the polyolefin film has a thickness of 50 to 150. mu.m, and may be, for example, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm.

Preferably, the thickness ratio of the composite layer, the core layer and the heat-sealing layer is 1 (2-3): 1-1.5, and may be, for example, 1:2:1, 1:2.2:1, 1:2.4:1, 1:2.6:1, 1:2.8:1, 1:3:1, 1:2:1.1, 1:2:1.2, 1:2:1.3, 1:2:1.4, 1:2:1.5, 1:2.2:1.1, 1:2.5:1.2, 1:2.8:1.3, 1:3:1.4, 1:3:1.5, preferably 1 (2-3): 1.

Preferably, in the material of the composite layer, the linear low density polyethylene has a melt index of 1-5g/10min, such as 1g/10min, 1.5g/10min, 2g/10min, 2.5g/10min, 3g/10min, 3.5g/10min, 4g/10min, 4.5g/10min, 5g/10 min.

Preferably, in the material of the composite layer, the low density polyethylene has a melt index of 1-5g/10min, and may be, for example, 1g/10min, 1.5g/10min, 2g/10min, 2.5g/10min, 3g/10min, 3.5g/10min, 4g/10min, 4.5g/10min, 5g/10 min.

Preferably, in the material of the composite layer, the ultraviolet absorbent includes any one of a high molecular weight benzophenone-based absorbent or a benzotriazole-based absorbent or a combination of at least two of them.

Preferably, in the material of the composite layer, the high molecular weight benzophenone-based absorber comprises any one of UV-531 (2-hydroxy-4-n-octoxybenzophenone), UV-981 or UV-1009 or the combination of at least two of the UV-531, the UV-4-n-octoxybenzophenone and the UV-1009. UV-981 and UV-1009 isocyanurate, higher fatty acid and 2, 4-dihydroxy benzophenone under the action of catalyst.

Preferably, in the material of the composite layer, the benzotriazole-based absorbent includes any one of UV-326(2'- (2' -hydroxy-3 '-tert-butyl-5' -methylphenyl) -5-chlorobenzotriazole), UV327(2- (2 '-hydroxy-3', 5 '-di-tert-butylphenyl) -5-chlorobenzotriazole) or UV-360(2,2' -methylenebis (4-tert-octyl-6-benzotriazolylphenol)) or a combination of at least two thereof.

Preferably, in the material of the composite layer, the light stabilizer comprises UV3529 and/or light stabilizer 622.

Preferably, in the material of the composite layer, the material of the composite layer further comprises an antioxidant.

Preferably, the antioxidant comprises antioxidant 1076 and/or antioxidant 168 in the material of the composite layer.

Preferably, in the material of the composite layer, the material of the composite layer further comprises a processing aid.

Preferably, in the material of the composite layer, the processing aid comprises a PPA aid and/or an opening agent.

The PPA additive is a polymer processing additive taking a fluorine-containing high molecular polymer as a basic structure. The significance in the composite co-extruded film is as follows: the gloss of the product is improved to a certain extent, the processability of the resin is improved, the extrusion efficiency of co-extrusion is improved, and the processing temperature of the resin is reduced.

Preferably, in the material of the composite layer, the opening agent is a silicon dioxide opening agent.

Preferably, in the material of the composite layer, the particle size of the silicon dioxide opening agent is 4-5 μm, and may be, for example, 4 μm, 4.1 μm, 4.2 μm, 4.3 μm, 4.4 μm, 4.5 μm, 4.6 μm, 4.7 μm, 4.8 μm, 4.9 μm, or 5 μm.

Preferably, the material of the composite layer comprises, in weight percent: 60-78% of linear low density polyethylene, 20-38% of low density polyethylene, 0.5-1% of ultraviolet absorber, 0.5-1% of light stabilizer, 0.5-1% of antioxidant and 0.5-2% of processing aid.

In the material of the composite layer of the present invention, the antioxidant may be 0.5 to 1% by weight, for example, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%.

In the material of the composite layer of the present invention, the processing aid may be 0.5 to 2% by weight, for example, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%.

Preferably, the linear low density polyethylene has a melt index of 1-5g/10min, for example, 1g/10min, 1.5g/10min, 2g/10min, 2.5g/10min, 3g/10min, 3.5g/10min, 4g/10min, 4.5g/10min, 5g/10min in the material of the core layer.

Preferably, in the material of the core layer, the low density polyethylene has a melt index of 1-5g/10min, and may be, for example, 1g/10min, 1.5g/10min, 2g/10min, 2.5g/10min, 3g/10min, 3.5g/10min, 4g/10min, 4.5g/10min, 5g/10 min.

Preferably, in the material of the core layer, the ultraviolet absorbent comprises any one of or a combination of at least two of a high molecular weight benzophenone-based absorbent or a benzotriazole-based absorbent;

preferably, in the material of the core layer, the high molecular weight benzophenone absorbent comprises any one of UV-531, UV-981 or UV-1009 or the combination of at least two of the UV-531, UV-981 and UV-1009;

preferably, in the material of the core layer, the benzotriazole-based absorber comprises any one or a combination of at least two of UV-326, UV327 or UV-360;

preferably, in the material of the core layer, the light stabilizer comprises UV3529 and/or light stabilizer 622;

preferably, in the material of the core layer, the material of the core layer further comprises an antioxidant;

preferably, in the material of the core layer, the antioxidant comprises antioxidant 1076 and/or antioxidant 168;

preferably, the core layer comprises the following materials in percentage by weight: 60-75% of linear low density polyethylene, 20-35% of low density polyethylene, 2-6% of ultraviolet absorbent, 1-3% of light stabilizer and 0.5-1% of antioxidant.

In the core layer material of the present invention, the antioxidant may be 0.5 to 1% by weight, for example, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%.

Preferably, in the material of the heat-seal layer, the linear low-density polyethylene has a melt index of 1-5g/10min, and may be, for example, 1g/10min, 1.5g/10min, 2g/10min, 2.5g/10min, 3g/10min, 3.5g/10min, 4g/10min, 4.5g/10min, 5g/10 min.

Preferably, in the material of the heat-sealing layer, the low-density polyethylene has a melt index of 1-5g/10min, and may be, for example, 1g/10min, 1.5g/10min, 2g/10min, 2.5g/10min, 3g/10min, 3.5g/10min, 4g/10min, 4.5g/10min, 5g/10 min.

Preferably, in the material of the heat-sealing layer, the ultraviolet absorbent comprises any one of or a combination of at least two of a high molecular weight benzophenone-based absorbent or a benzotriazole-based absorbent;

preferably, in the material of the heat sealing layer, the high molecular weight benzophenone absorbent comprises any one of UV-531, UV-981 or UV-1009 or the combination of at least two of the UV-531, the UV-981 or the UV-1009;

preferably, in the material of the heat-sealing layer, the benzotriazole-based absorbent comprises any one of UV-326, UV327 or UV-360 or a combination of at least two of the UV-326, the UV327 and the UV-360;

preferably, in the material of the heat-seal layer, the light stabilizer comprises UV3529 and/or light stabilizer 622;

preferably, in the material of the heat-sealing layer, the material of the heat-sealing layer further comprises an antioxidant;

preferably, in the material of the heat-seal layer, the antioxidant comprises antioxidant 1076 and/or antioxidant 168;

preferably, in the material of the heat-sealing layer, the material of the heat-sealing layer further comprises a processing aid;

preferably, in the material of the heat-seal layer, the processing aid comprises a PPA aid and/or an opening agent

Preferably, in the material of the heat-sealing layer, the opening agent is a silicon dioxide opening agent;

preferably, in the material of the heat-seal layer, the particle size of the silica opening agent is 4 to 5 μm, and may be, for example, 4 μm, 4.1 μm, 4.2 μm, 4.3 μm, 4.4 μm, 4.5 μm, 4.6 μm, 4.7 μm, 4.8 μm, 4.9 μm, or 5 μm.

Preferably, the material of the heat-sealing layer comprises the following components in percentage by weight: 60-75% of linear low density polyethylene, 20-35% of low density polyethylene, 1.5-3% of ultraviolet absorbent, 0.5-2% of light stabilizer, 0.5-1% of antioxidant and 0.5-2% of processing aid.

In the material of the heat-seal layer of the present invention, the antioxidant may be 0.5 to 1% by weight, for example, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%.

In the material of the heat-sealable layer of the present invention, the processing aid may be 0.5 to 2% by weight, for example, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%.

In a second aspect, the present invention provides a method for producing a polyolefin film for a transparent back sheet film as described in the first aspect, the method comprising the steps of:

(1) respectively mixing the materials of the composite layer, the core layer and the heat sealing layer to obtain a composite layer premix, a core layer premix and a heat sealing layer premix;

(2) respectively blending the composite layer premix, the core layer premix and the heat sealing layer premix obtained in the step (1) to obtain composite layer compound particles, core layer compound particles and heat sealing layer compound particles;

(3) and (3) carrying out melting plasticization, extrusion and sizing on the composite layer compound particles, the core layer compound particles and the heat sealing layer compound particles obtained in the step (2) to obtain the polyolefin film for the transparent back plate film.

Preferably, the mixing of step (1) is carried out in a high speed mixer.

Preferably, the rotation speed of the high-speed mixer in the mixing in the step (1) is 500-1000rpm, such as 500rpm, 600rpm, 700rpm, 800rpm, 900rpm and 1000 rpm.

Preferably, the blending of step (2) is carried out in a twin screw extruder.

Preferably, the temperature of the blending in step (2) is 150 ℃ and 250 ℃, for example, 150 ℃, 160 ℃, 170 ℃, 180 ℃, 200 ℃, 210 ℃, 220 ℃, 230 ℃, 240 ℃, 250 ℃.

Preferably, the melt-plasticization of step (3) is performed in a multilayer coextrusion casting apparatus or a film blowing apparatus.

Preferably, the temperature for the melt plasticizing in the step (3) is 160-.

Preferably, the shaping in step (3) is cooling shaping.

Preferably, step (3) is followed by step (4): and carrying out corona treatment on the transparent back plate film by using a polyolefin film, and winding to obtain a finished product.

Preferably, the preparation method comprises the following steps:

(1) respectively putting the materials of the composite layer, the core layer and the heat sealing layer into a high-speed mixer with the speed of 500-1000rpm for uniform mixing to obtain a composite layer premix, a core layer premix and a heat sealing layer premix;

(2) respectively carrying out blending modification granulation on the composite layer premix, the core layer premix and the heat sealing layer premix obtained in the step (1) at the temperature of 150 ℃ and 250 ℃ by a double-screw extruder to obtain composite layer compound particles, core layer compound particles and heat sealing layer compound particles;

(3) melting and plasticizing the composite layer compound particles, the core layer compound particles and the heat sealing layer compound particles obtained in the step (2) in multilayer coextrusion casting equipment or film blowing equipment at the temperature of 160-250 ℃, extruding through a die head, and cooling and shaping to obtain the polyolefin film for the transparent back plate film;

(4) and (4) carrying out corona treatment on the transparent back plate film obtained in the step (3) by using a polyolefin film, and winding to obtain a finished product.

Compared with the prior art, the invention has the following beneficial effects:

(1) the polyolefin film comprises a composite layer, a core layer and a heat sealing layer which are sequentially laminated, wherein the materials of each layer comprise linear low-density polyethylene and low-density polyethylene, and the two polyethylene materials are matched with each other to realize synergistic interaction, so that the mechanical property of each layer is improved, and the film is ensured to have good processability and light transmittance.

(2) In the invention, the polyolefin film has excellent ultraviolet resistance and high light transmittance, the ultraviolet transmittance to the wavelength of 280-380nm is below 15%, and the light transmittance to visible light is above 90%; the back sheet made of the polyolefin film has the peeling strength of the film and PET of more than 5N/cm and the bonding strength of the film and EVA of more than 70N/cm, and has excellent light transmission, ultraviolet resistance and insulation.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.