A tear-resistant and light-transmissive composite film, its preparation method and application

Abstract

The present invention belongs to the field of membrane material technology and discloses a tear-resistant, light-transmitting composite film and its preparation method and application. The composite film, from bottom to top, comprises, in sequence, a blown film layer, a cloth base layer, and a mask layer; the cloth base layer is formed by interweaving warp and weft threads, and in the cloth base layer, the spacing between each two adjacent warp and weft threads is 0.5-2.5 cm; the components of the blown film layer include metallocene linear polyethylene, low-density polyethylene, and ethylene-vinyl acetate copolymer; the components of the mask layer include low-density polyethylene and linear low-density polyethylene. The composite film has excellent light transmittance, for example, a visible light transmittance of not less than 90%. When used in greenhouses for planting, it can greatly improve the strength of the greenhouse, effectively resist storms and hail, and greatly extend the service life of the greenhouse.

Description

Technical Field

[0001] The present invention belongs to the technical field of membrane materials, and in particular relates to a tear-resistant, light-transmitting composite membrane and a preparation method and application thereof. Background Art

[0002] Agricultural greenhouse films, such as light-reflecting films and anti-fog films, play a vital role in improving crop yield and quality and shortening the crop growth cycle. However, existing greenhouse films often have poor mechanical properties. They can easily tear, become punctured, or become damaged after one to two years of use, or in extreme weather conditions such as hail, storms, and heavy rain, becoming discarded plastic. This significantly increases the environmental burden and costs for farmers.

[0003] Invention patent CN109130409A discloses a PE (polyethylene) greenhouse film produced by coextrusion blow molding using PE with a specific density, melt index, and molecular weight and a certain content of EVA (ethylene-vinyl acetate copolymer). While density, melt index, and molecular weight determine the basic physical properties of PE greenhouse film, polymers require stretching and orientation to achieve higher mechanical properties. Films (especially those produced by blow molding) with low orientation levels often exhibit limited mechanical properties.

[0004] Invention patent CN102952310A discloses a metallocene polyethylene agricultural film. By modifying m-LLDPE (metallocene linear polyethylene), a film with good tear strength is blown. This patent is aimed at modifying the raw materials and preparing the film by blow molding. However, the blow molding method has low mechanical properties due to the low orientation of the polymer during the processing process.

[0005] Invention patent CN105440269A discloses a tear-resistant, biaxially oriented polyester greenhouse film. This patented film is made from polyester (PET) material using a biaxial stretching process. Biaxial stretching offers the advantage of high tensile strength, but significantly reduces tear resistance. Polyester (PET) material has irregular crystallization, which significantly affects transparency and hinders light transmittance.

[0006] If the existing greenhouse film focuses on improving its mechanical properties, its light transmittance is often poor, and the visible light transmittance is often difficult to exceed 88%.

[0007] Therefore, there is an urgent need to provide a new film that not only has good mechanical properties but also has good light transmittance. Summary of the Invention

[0008] The present invention aims to address at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention provides a tear-resistant, light-transmitting composite film, a preparation method, and applications thereof. The film not only has good mechanical properties but also has good light transmittance, for example, a visible light transmittance of not less than 90%.

[0009] The inventive concept of the present invention is as follows: the composite film of the present invention has a three-layer structure, which includes, from bottom to top, a blown film layer, a cloth base layer, and a mask layer; the cloth base layer is formed by interweaving warp and weft yarns, and in the cloth base layer, the spacing between every two adjacent warp and weft yarns is 0.5-2.5 cm (preferably 0.5-2.0 cm). The present invention weaves a lightweight, porous cloth base layer (as a skeleton), blows a film, and then uses cast film composite to form a composite film reinforced by a woven skeleton while forming the mask. Since the cloth base layer has a porous structure, the resulting composite film has good light transmittance. When used in greenhouses for planting, it can greatly improve the strength of the greenhouse, effectively resist storms and hail, and greatly extend the service life of the greenhouse.

[0010] A first aspect of the present invention provides a tear-resistant, light-transmitting composite film.

[0011] Specifically, a tear-resistant, light-transmitting composite film comprises, from bottom to top, a blown film layer, a fabric base layer, and a mask layer;

[0012] The base fabric is formed by interweaving warp and weft threads, and the distance between every two adjacent warp and weft threads in the base fabric is 0.5-2.5 cm;

[0013] The components of the blown film layer include metallocene linear polyethylene (m-LLDPE), low density polyethylene (LDPE), and ethylene vinyl acetate copolymer (EVA);

[0014] The components of the facial mask layer include low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE).

[0015] Preferably, the components of the warp and weft in the fabric base layer include high-density polyethylene (HDPE), light stabilizer masterbatch, and anti-reflection masterbatch.

[0016] Preferably, the light stabilizer masterbatch includes a hindered amine light stabilizer, a UV absorber, high-density polyethylene (HDPE), low-density polyethylene (LDPE), and an antioxidant.

[0017] Preferably, the hindered amine light stabilizer is selected from at least one of BASF's FD944 and FD770, and Cytec's UV3853 and UV3529.

[0018] Preferably, the ultraviolet absorber is selected from UV328, UV327 of BASF, UV2908, UV531 of Cytec,

[0019] Preferably, the light stabilizer masterbatch comprises, by weight, 5-25 parts of hindered amine light stabilizer, 5-15 parts of ultraviolet absorber, 20-50 parts of high-density polyethylene (HDPE), 20-60 parts of low-density polyethylene (LDPE), and 1-5 parts of antioxidant; further preferably, the light stabilizer masterbatch comprises, by weight, 5-15 parts of hindered amine light stabilizer, 5-10 parts of ultraviolet absorber, 30-50 parts of high-density polyethylene (HDPE), 30-60 parts of low-density polyethylene (LDPE), and 1-3 parts of antioxidant.

[0020] Preferably, the components of the warp and weft yarns in the cloth base layer, by weight, include 85-97.5 parts of high-density polyethylene (HDPE), 2-10 parts of light stabilizer masterbatch, and 0.5-5 parts of anti-reflection masterbatch; further preferably, the components of the warp and weft yarns in the cloth base layer, by weight, include 91-97.5 parts of high-density polyethylene (HDPE), 2-6 parts of light stabilizer masterbatch, and 0.5-3 parts of anti-reflection masterbatch.

[0021] Preferably, the density of the warp yarns in the base fabric is controlled at 5-35 yarns / 10 cm, and the density of the weft yarns is controlled at 5-35 yarns / 10 cm; further preferably, the density of the warp yarns in the base fabric is controlled at 5-30 yarns / 10 cm, and the density of the weft yarns is controlled at 5-30 yarns / 10 cm.

[0022] Preferably, the density of the base fabric is 28-135 g / m 2 Further preferably, the density of the base fabric is 28-130g / m 2 .

[0023] Preferably, the width of the warp and weft in the base fabric is 1.2-5.5 mm; further preferably, the width of the warp and weft in the base fabric is 1.5-3.5 mm.

[0024] Preferably, the components of the blown film layer include, by weight, 30-60 parts of metallocene linear polyethylene (m-LLDPE), 10-30 parts of low-density polyethylene (LDPE), and 10-30 parts of ethylene-vinyl acetate copolymer (EVA).

[0025] Preferably, the components of the blown film layer also include light stabilizer masterbatch and anti-reflection masterbatch.

[0026] Preferably, the components of the blown film layer include, by weight, 30-60 parts of metallocene linear polyethylene (m-LLDPE), 10-30 parts of low-density polyethylene (LDPE), 10-30 parts of ethylene-vinyl acetate copolymer (EVA), 2-6 parts of light stabilizer masterbatch, and 0.5-3 parts of anti-reflection masterbatch.

[0027] Preferably, the components of the mask layer also include light stabilizer masterbatch, and in parts by weight, include 40-50 parts of low-density polyethylene (LDPE), 50-60 parts of linear low-density polyethylene (LLDPE), and 3-10 parts of light stabilizer masterbatch.

[0028] Preferably, the thickness of the blown film layer is 0.05-0.6 mm; further preferably, the thickness of the blown film layer is 0.05-0.3 mm.

[0029] Preferably, the density of the mask layer is 10-120 g / m 2 Further preferably, the density of the mask layer is 20-100g / m 2 .

[0030] A second aspect of the present invention provides a method for preparing a tear-resistant, light-transmitting composite film.

[0031] Specifically, a method for preparing a tear-resistant, light-transmitting composite film comprises the following steps:

[0032] (1) Preparation of the fabric base: high-density polyethylene (HDPE), light stabilizer masterbatch, and anti-reflection masterbatch are mixed, extruded, cut into strips, stretched, shaped, and rolled into spindles, which are then woven into the fabric base;

[0033] (2) Preparation of blown film layer: Metallocene linear polyethylene (m-LLDPE), low-density polyethylene (LDPE), and ethylene-vinyl acetate copolymer (EVA) are mixed and blown into a blown film layer;

[0034] (3) Preparation of the mask layer: The blown film layer is placed at the bottom, and the cloth base layer is stacked on the blown film layer. Then, low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE) are mixed, melt-extruded and cast onto the cloth base layer to form a mask layer on the surface of the cloth base layer, and then cooled to obtain the composite film.

[0035] Preferably, in step (1), the preparation process of the light stabilizer masterbatch is to mix the hindered amine light stabilizer, the ultraviolet absorber, the high-density polyethylene (HDPE), the low-density polyethylene (LDPE), and the antioxidant, and extrude and granulate to obtain the light stabilizer masterbatch.

[0036] Preferably, in step (1), the extrusion process is carried out in a screw extruder.

[0037] Preferably, in step (1), the stretching process is to stretch more than 7 times, for example, if the length of the strip obtained by cutting is 1 unit, it is stretched to more than 7 times the length, for example, 7-12 times the length.

[0038] Preferably, in step (1), after the stretching, the tensile strength of a single silk ingot is ≥0.46N / tex, and the thermal shrinkage rate of the single silk ingot is 3% or less.

[0039] Preferably, in step (1), the process of weaving the silk spindles into the cloth base layer can be carried out by using a water loom, a circular loom, or a projectile loom.

[0040] Preferably, in step (2), metallocene linear polyethylene (m-LLDPE), low-density polyethylene (LDPE), ethylene-vinyl acetate copolymer (EVA), light stabilizer masterbatch, and anti-reflection masterbatch are mixed and blown into a blown film layer.

[0041] Preferably, in step (2), a single-screw film blowing machine is used to blow the film into the blown film layer.

[0042] Preferably, in step (3), a single-screw extruder is used for melt extrusion.

[0043] Preferably, in step (3), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE) and light stabilizer masterbatch are mixed.

[0044] In step (3), since the fabric base layer is porous, part of the cast mixture will pass through the fabric base layer, bonding the blown film layer to the fabric base layer. At the same time, there is also a layer of cast mixture above the fabric base layer, which will eventually form a mask layer.

[0045] The blown film layer, the base fabric layer, and the mask layer are bonded together to form a whole. The base fabric layer is the core of the significantly improved mechanical properties of the composite film, which can significantly improve the tensile and tear strength of the composite film. At the same time, the one-time laminating and laminating (step (3) is also a laminating process) reduces the damage of the cast mixture to the base fabric layer. Because the base fabric layer has pores, it is more translucent than ordinary woven agricultural films. Therefore, the base fabric layer prepared by this method can overcome the disadvantage of low mechanical strength of the blown film while maintaining the translucency of the blown film, thus overcoming the disadvantage of low translucency of the woven greenhouse film.

[0046] A third aspect of the present invention provides an application of a tear-resistant, light-transmitting composite film.

[0047] Application of the tear-resistant and light-transmitting composite film in agricultural greenhouse film.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] The composite film of the present invention has a three-layer structure, which includes, from bottom to top, a blown film layer, a cloth base layer, and a facial mask layer; the cloth base layer is formed by interweaving warp and weft, and in the cloth base layer, the spacing between every two adjacent warp and weft is 0.5-2.5cm (preferably 0.5-2.0cm). The present invention is through weaving a lightweight porous cloth base layer (as a skeleton), a blown film, and then through cast composite, while forming a facial mask, the blown film layer and the cloth base layer are bonded together to form a composite film with a woven skeleton reinforcement. Because the cloth base layer has a porous structure, the composite film obtained has good light transmittance, for example, the transmittance of visible light is not less than 90%. It is used in greenhouses for planting, can well improve the strength of the greenhouse, effectively resist storms and hail, and greatly extend the service life of the greenhouse. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 Schematic diagram of the structure of the composite membrane prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0051] In order to make the technical solution of the present invention more clearly understood by those skilled in the art, the following examples are given for illustration. It should be noted that the following examples do not limit the scope of protection claimed by the present invention.

[0052] Unless otherwise specified, the raw materials, reagents, or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0053] The antireflection masterbatch used in the following examples was prepared according to the method of Example 2 of CN104530546A.

[0054] Example 1

[0055] A method for preparing a tear-resistant, light-transmitting composite film comprises the following steps:

[0056] (1) Preparation of fabric base: The preparation process of light stabilizer masterbatch is to mix hindered amine light stabilizer (model FD944), ultraviolet absorber (model UV328), high density polyethylene (HDPE), low density polyethylene (LDPE), antioxidant (1010 antioxidant) in a weight ratio of 10:9:40:40:1, and extrude granulate in a twin-screw granulator (the temperature distribution of barrel 1, barrel 2, barrel 3, barrel 4, barrel 5, barrel 6, filter area, connector, and die head in the twin-screw granulator is: 180℃, 200℃, 210℃, 220℃, 220℃, 225℃, 230℃, 235℃, 236℃, 237℃, 238℃, 240℃, 250℃, 260℃, 270℃, 275℃, 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, 350℃, 360℃, 370℃, 380℃, 390℃, 400℃, 410℃, 410℃, 420℃, 430℃, 440℃, 450℃, 460℃, 470℃, 480℃, 490℃, 500℃, 510℃, 510℃, 520℃, 53 ... 0℃, 220℃) to prepare a light stabilizer masterbatch; high-density polyethylene (HDPE), light stabilizer masterbatch, and anti-reflection masterbatch are mixed in a weight ratio of 100:4:1, extruded, cut into strips, stretched, shaped, and rolled into spindles, and then the spindles are woven into a cloth base using a water loom, the spindle width is 2.5mm, the spindle linear density is 80tex, the tensile strength is 0.48N / tex, the density of the warp yarns in the cloth base is 20 / 10cm, the density of the weft yarns is 20 / 10cm (that is, the spacing between every two adjacent warp yarns and weft yarns is in the range of 0.5-2.5cm), and the weight per unit area of the cloth base is 32g / m 2 ;

[0057] (2) Preparation of blown film layer: Metallocene linear polyethylene (m-LLDPE), low density polyethylene (LDPE), ethylene-vinyl acetate copolymer (EVA), light stabilizer masterbatch: antireflection masterbatch are mixed in a weight ratio of 50:25:20:4:1, and kneaded in an extruder (the temperature distribution of barrel 1, barrel 2, barrel 3, barrel 4, barrel 5, barrel 6, filter area, connector, and die head in the extruder is: 160°C, 180°C, 200°C, 200°C, 220°C, 225°C, 225°C, 225°C, 220°C), and a film embryo is extruded. The film embryo is blown and cooled with 30°C wind, and the blowing ratio is 3 times, and then blown into a blown film layer with a thickness of 0.1 mm and a unit area weight of 100 g / m 2 ;

[0058] (3) Preparation of the mask layer: Place the blown film layer at the bottom, and stack the fabric base layer on top of the blown film layer. Then, mix low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and light stabilizer masterbatch in a weight ratio of 50:45:5, and mix in an extruder (the temperature distribution of barrel 1, barrel 2, barrel 3, barrel 4, barrel 5, barrel 6, filter area, connector, and die head in the extruder is: 180°C, 230°C, 250°C, 260°C, 260°C, 270°C, 270°C, 275°C, and 270°C). Melt-extrude and single-sided cast coating is applied to the fabric base layer to form a mask layer on the surface of the fabric base layer. The weight per unit area of the mask layer is 35 g / m2 , and then cooled to obtain a composite membrane.

[0059] Figure 1 Schematic diagram of the structure of the composite membrane prepared in Example 1 of the present invention. Figure 1 100 represents the blown film layer, 200 represents the fabric base layer, and 300 represents the mask layer.

[0060] Example 2

[0061] A method for preparing a tear-resistant, light-transmitting composite film comprises the following steps:

[0062] (1) Preparation of fabric base: The preparation process of light stabilizer masterbatch is to mix hindered amine light stabilizer (model UV3529), ultraviolet absorber (model UV360), high density polyethylene (HDPE), low density polyethylene (LDPE), antioxidant (1010 antioxidant) in a weight ratio of 10:9:20:60:1, and extrude granulation in a twin-screw granulator (the temperature distribution of barrel 1, barrel 2, barrel 3, barrel 4, barrel 5, barrel 6, filter area, connector, and die head in the twin-screw granulator is: 180℃, 200℃, 210℃, 220℃, 220℃, 23 ... 0℃, 225℃, 230℃, 230℃, 220℃) to prepare a light stabilizer masterbatch; high-density polyethylene (HDPE), light stabilizer masterbatch, and anti-reflection masterbatch are mixed in a weight ratio of 100:5:1, extruded, cut into strips, stretched, shaped, and rolled into spindles, and then the spindles are woven into a cloth base using a water loom, the spindle width is 2.0 mm, the spindle linear density is 100 tex, the tensile strength is 0.48 N / tex, the density of the warp yarns in the cloth base is 15 yarns / 10 cm, the density of the weft yarns is 15 yarns / 10 cm, and the weight per unit area of the cloth base is 30 g / m 2 ;

[0063] (2) Preparation of blown film layer: Metallocene linear polyethylene (m-LLDPE), low density polyethylene (LDPE), ethylene-vinyl acetate copolymer (EVA), light stabilizer masterbatch: antireflection masterbatch are mixed in a weight ratio of 60:15:20:4:1, and kneaded in an extruder (the temperature distribution of barrel 1, barrel 2, barrel 3, barrel 4, barrel 5, barrel 6, filter area, connector, and die head in the extruder is: 160°C, 180°C, 200°C, 200°C, 220°C, 225°C, 225°C, 220°C), and a film embryo is extruded. The film embryo is blown and cooled with 30°C wind, and the blowing ratio is 3 times, and blown into a blown film layer with a thickness of 0.08 mm. The weight per unit area of the blown film layer is 80 g / m 2 ;

[0064] (3) Preparation of the mask layer: Place the blown film layer at the bottom, and stack the fabric base layer on top of the blown film layer. Then, mix low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and light stabilizer masterbatch in a weight ratio of 40:45:10, and mix in an extruder (the temperature distribution of barrel 1, barrel 2, barrel 3, barrel 4, barrel 5, barrel 6, filter area, connector, and die head in the extruder is: 180°C, 230°C, 250°C, 260°C, 260°C, 270°C, 270°C, 275°C, and 270°C). Melt-extrude and single-sided cast coating is applied to the fabric base layer to form a mask layer on the surface of the fabric base layer. The weight per unit area of the mask layer is 50 g / m 2 , and then cooled to obtain a composite membrane.

[0065] Example 3

[0066] A method for preparing a tear-resistant, light-transmitting composite film comprises the following steps:

[0067] (1) Preparation of fabric base: The preparation process of light stabilizer masterbatch is to mix hindered amine light stabilizer (model 625), ultraviolet absorber (model UV360), high density polyethylene (HDPE), low density polyethylene (LDPE), antioxidant (1010 antioxidant) in a weight ratio of 8:6:25:60:1, and extrude granulate in a twin-screw granulator (the temperature distribution of barrel 1, barrel 2, barrel 3, barrel 4, barrel 5, barrel 6, filter area, connector, and die head in the twin-screw granulator is: 180℃, 200℃, 210℃, 220℃, 220℃, 225℃, 230 ... ℃, 230℃, 230℃, 220℃) to prepare a light stabilizer masterbatch; high-density polyethylene (HDPE, model 6094), light stabilizer masterbatch, and anti-reflection masterbatch are mixed in a weight ratio of 100:6:3, extruded, cut into strips, stretched, shaped, and rolled into spindles, and then the spindles are woven into a cloth base using a water loom. The width of the spindle is 2.7 mm, the linear density of the spindle is 160 tex, the tensile strength is 0.47 N / tex, the density of the warp yarns in the cloth base is 18 yarns / 10 cm, the density of the weft yarns is 15 yarns / 10 cm, and the weight per unit area of the cloth base is 54 g / m 2 ;

[0068] (2) Preparation of blown film layer: Metallocene linear polyethylene (m-LLDPE), low density polyethylene (LDPE), ethylene-vinyl acetate copolymer (EVA), light stabilizer masterbatch: antireflection masterbatch are mixed in a weight ratio of 32:30:30:6:2, and kneaded in an extruder (the temperature distribution of barrel 1, barrel 2, barrel 3, barrel 4, barrel 5, barrel 6, filter area, connector, and die head in the extruder is: 160°C, 180°C, 200°C, 200°C, 220°C, 225°C, 225°C, 225°C, 220°C), and a film embryo is extruded. The film embryo is blown and cooled with 30°C wind, and the blowing ratio is 3 times, and then blown into a blown film layer with a thickness of 0.2 mm and a unit area weight of 200 g / m 2 ;

[0069] (3) Preparation of the mask layer: Place the blown film layer at the bottom, and stack the fabric base layer on top of the blown film layer. Then, mix low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and light stabilizer masterbatch in a weight ratio of 42:50:8, and mix in an extruder (the temperature distribution of barrel 1, barrel 2, barrel 3, barrel 4, barrel 5, barrel 6, filter area, connector, and die head in the extruder is: 180°C, 230°C, 250°C, 260°C, 260°C, 270°C, 270°C, 275°C, and 270°C). Melt-extrude and single-sided cast coating is applied to the fabric base layer to form a mask layer on the surface of the fabric base layer. The weight per unit area of the mask layer is 70 g / m 2 , and then cooled to obtain a composite membrane.

[0070] Example 4

[0071] A method for preparing a tear-resistant, light-transmitting composite film comprises the following steps:

[0072] (1) Preparation of fabric base: The preparation process of light stabilizer masterbatch is to mix hindered amine light stabilizer (model FD944), ultraviolet absorber (model UV531), high density polyethylene (HDPE), low density polyethylene (LDPE), antioxidant (1076 antioxidant) in a weight ratio of 15:4:20:60:1, and extrude granulation in a twin-screw granulator (the temperature distribution of barrel 1, barrel 2, barrel 3, barrel 4, barrel 5, barrel 6, filter area, connector, and die head in the twin-screw granulator is: 180℃, 200℃, 210℃, 220℃, 220℃, 23 ... 0℃, 225℃, 230℃, 230℃, 220℃) to prepare a light stabilizer masterbatch; high-density polyethylene (HDPE), light stabilizer masterbatch, and anti-reflection masterbatch are mixed in a weight ratio of 100:4:2, extruded, cut into strips, stretched, shaped, and rolled into spindles, and then the spindles are woven into a cloth base using a water loom. The width of the spindle is 3.0 mm, the linear density of the spindle is 200 tex, the tensile strength is 0.47 N / tex, the density of the warp yarn in the cloth base is 20 yarns / 10 cm, the density of the weft yarn is 18 yarns / 10 cm, and the weight per unit area of the cloth base is 78 g / m 2 ;

[0073] (2) Preparation of blown film layer: Metallocene linear polyethylene (m-LLDPE), low density polyethylene (LDPE), ethylene-vinyl acetate copolymer (EVA), light stabilizer masterbatch: antireflection masterbatch are mixed in a weight ratio of 60:15:18:5:2, and kneaded in an extruder (the temperature distribution of barrel 1, barrel 2, barrel 3, barrel 4, barrel 5, barrel 6, filter area, connector, and die head in the extruder is: 160°C, 180°C, 200°C, 200°C, 220°C, 225°C, 225°C, 225°C, 220°C), and a film embryo is extruded. The film embryo is blown and cooled with 30°C wind, and the blowing ratio is 3 times, and then blown into a blown film layer with a thickness of 0.25 mm and a unit area weight of 250 g / m 2 ;

[0074] (3) Preparation of the mask layer: Place the blown film layer at the bottom, and stack the fabric base layer on top of the blown film layer. Then, mix low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and light stabilizer masterbatch in a weight ratio of 60:30:10, and mix in an extruder (the temperature distribution of barrel 1, barrel 2, barrel 3, barrel 4, barrel 5, barrel 6, filter area, connector, and die head in the extruder is: 180°C, 230°C, 250°C, 260°C, 260°C, 270°C, 270°C, 275°C, and 270°C). Melt-extrude and single-sided cast coating is applied to the fabric base layer to form a mask layer on the surface of the fabric base layer. The weight per unit area of the mask layer is 85g / m 2 , and then cooled to obtain a composite membrane.

[0075] Example 5

[0076] A method for preparing a tear-resistant, light-transmitting composite film comprises the following steps:

[0077] (1) Preparation of fabric base: The preparation process of light stabilizer masterbatch is to mix hindered amine light stabilizer (model 783), ultraviolet absorber (model UV360), high density polyethylene (HDPE), low density polyethylene (LDPE), antioxidant (1076 antioxidant) in a weight ratio of 10:3:50:35:2, and extrude granulation in a twin-screw granulator (the temperature distribution of barrel 1, barrel 2, barrel 3, barrel 4, barrel 5, barrel 6, filter area, connector, and die head in the twin-screw granulator is: 180℃, 200℃, 210℃, 220℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, 340℃, 360℃, 370℃, 380℃, 390℃, 400℃, 410℃, 420℃, 430℃, 440℃, 450℃, 460℃, 470℃, 480℃, 490℃, 500℃, 510℃, 510℃, 520℃, 530℃, 530℃, 540℃, 550℃, 560℃, 570℃, 580℃, 590℃, 600℃, 610℃, 600℃, 610℃, 600℃, 600℃, 610℃, 420℃, 5 ℃, 225℃, 230℃, 230℃, 220℃) to prepare a light stabilizer masterbatch; high-density polyethylene (HDPE), light stabilizer masterbatch, and anti-reflection masterbatch are mixed in a weight ratio of 100:6:3, extruded, cut into strips, stretched, shaped, and rolled into spindles, and then the spindles are woven into a cloth base using a water loom. The width of the spindle is 1.8 mm, the linear density of the spindle is 150 tex, the tensile strength is 0.48 N / tex, the density of the warp yarns in the cloth base is 28 yarns / 10 cm, the density of the weft yarns is 25 yarns / 10 cm, and the weight per unit area of the cloth base is 82 g / m 2 ;

[0078] (2) Preparation of blown film layer: Metallocene linear polyethylene (m-LLDPE), low density polyethylene (LDPE), ethylene-vinyl acetate copolymer (EVA), light stabilizer masterbatch: antireflection masterbatch are mixed in a weight ratio of 53:20:20:6:1, and kneaded in an extruder (the temperature distribution of barrel 1, barrel 2, barrel 3, barrel 4, barrel 5, barrel 6, filter area, connector, and die head in the extruder is: 160°C, 180°C, 200°C, 200°C, 220°C, 225°C, 225°C, 225°C, 220°C), and a film embryo is extruded. The film embryo is blown and cooled with 30°C wind, and the blowing ratio is 3 times, and then blown into a blown film layer with a thickness of 0.15 mm and a unit area weight of 150 g / m 2 ;

[0079] (3) Preparation of the mask layer: Place the blown film layer at the bottom, and stack the fabric base layer on top of the blown film layer. Then, mix low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and light stabilizer masterbatch in a weight ratio of 44:50:6, and mix in an extruder (the temperature distribution of barrel 1, barrel 2, barrel 3, barrel 4, barrel 5, barrel 6, filter area, connector, and die head in the extruder is: 180°C, 230°C, 250°C, 260°C, 260°C, 270°C, 270°C, 275°C, and 270°C). Melt-extrude and single-sided cast coating is applied to the fabric base layer to form a mask layer on the surface of the fabric base layer. The weight per unit area of the mask layer is 65g / m 2 , and then cooled to obtain a composite membrane.

[0080] Product effect testing

[0081] The composite films prepared in Examples 1-5 were tested for their corresponding properties. The results are shown in Table 1.

[0082]

[0083] It can be seen from Table 1 that the composite film prepared in the embodiment of the present invention has good tear resistance, good mechanical effect, and good light transmittance.

Claims

1. A composite membrane, characterized in that From bottom to top, it includes blown film layer, cloth base layer, and mask layer; The base fabric is formed by interweaving warp and weft threads, and the distance between every two adjacent warp and weft threads in the base fabric is 0.5-2.5 cm; The components of the blown film layer include metallocene linear polyethylene, low-density polyethylene, and ethylene-vinyl acetate copolymer; The components of the facial mask layer include low-density polyethylene and linear low-density polyethylene; The density of the warp yarns in the base fabric is controlled at 18-20 yarns / 10 cm, and the density of the weft yarns is controlled at 15-20 yarns / 10 cm; The width of the warp and weft yarns in the base fabric is 2.5-3.0 mm; The components of the blown film layer, calculated by weight, include 30-60 parts of metallocene linear polyethylene, 10-30 parts of low-density polyethylene, and 10-30 parts of ethylene-vinyl acetate copolymer; The components of the mask layer also include a light stabilizer masterbatch, and by weight, the components of the mask layer include 40-50 parts of low-density polyethylene, 50-60 parts of linear low-density polyethylene, and 3-10 parts of light stabilizer masterbatch; The composite film is prepared by a preparation method comprising the following steps: (1) Preparation of the fabric base: mixing high-density polyethylene, light stabilizer masterbatch, and anti-reflection masterbatch, extruding, cutting into strips, stretching, shaping, and winding into spindles, which are then woven into the fabric base; (2) Preparation of blown film layer: mixing metallocene linear polyethylene, low-density polyethylene, and ethylene-vinyl acetate copolymer, and blowing them into a blown film layer; (3) Preparation of the mask layer: the blown film layer is placed at the bottom, the cloth base layer is stacked on the blown film layer, and then low-density polyethylene and linear low-density polyethylene are mixed, melt-extruded and cast onto the cloth base layer, a mask layer is formed on the surface of the cloth base layer, and then cooled to obtain the composite film.

2. The composite membrane according to claim 1, characterized in that The components of the warp and weft in the fabric base layer include high-density polyethylene, light stabilizer masterbatch, and anti-reflection masterbatch.

3. The composite membrane according to claim 2, characterized in that The light stabilizer masterbatch comprises a hindered amine light stabilizer, an ultraviolet absorber, high-density polyethylene, low-density polyethylene, and an antioxidant.

4. The composite membrane according to claim 2, characterized in that The components of the warp and weft in the base fabric include, by weight, 85-97.5 parts of high-density polyethylene, 2-10 parts of light stabilizer masterbatch, and 0.5-5 parts of anti-reflection masterbatch.

5. Use of the composite film according to any one of claims 1 to 4 in agricultural greenhouse films.

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