A greenhouse film, and a preparation method and application thereof

Abstract

The present application belongs to the technical field of plastic product production, and relates to a greenhouse film and a preparation method and application thereof. The weaving layer of the greenhouse film comprises 88.8-96.95 parts of high-density polyethylene, 0-5 parts of low-density polyethylene, 0.05-0.2 parts of graphene and 3-6 parts of anti-aging concentrated master batch. The formula of the outer surface layer and the inner surface layer comprises 33.8-46.95 parts of low-density polyethylene, 50-60 parts of linear low-density polyethylene, 0.05-0.2 parts of graphene and 3-6 parts of anti-aging concentrated master batch. The formula of the outer surface layer comprises 15-25 parts of low-density polyethylene and 18.7-26.9 parts of linear low-density polyethylene. The outer surface layer contains 50-60 parts of polydimethylsiloxane anti-fog drop master batch and 65800.1-0.3 parts of color master batch. The greenhouse film has the advantages of long-acting anti-fog drop and good strength, and can reduce the use cost, improve the crop yield and reduce the environmental pollution caused by plastic degradation.

Description

Technical Field

[0001] This invention belongs to the field of plastic product manufacturing technology, specifically relating to a greenhouse film, its preparation method and application. This greenhouse film is applied in the field of greenhouses and is a new type of agricultural greenhouse film. Background Technology

[0002] Currently, the main types of greenhouse films used in agricultural production include polyvinyl chloride (PVC) film, polyethylene (PE) film, and ethylene-vinyl acetate copolymer (EVA) film. PVC greenhouse film has good heat retention, light transmission, and weather resistance; it is soft and easy to shape. However, its disadvantages include high density, high cost, and tendency to harden and become brittle at low temperatures, and soften and loosen at high temperatures. After additives are released, the film surface attracts dust, affecting light transmission, and residual film is not easily recycled, producing chlorine gas. This type of greenhouse film has a maximum lifespan of 12 months and is being phased out. PE greenhouse film is lightweight, soft, easy to shape, has good light transmission, and is non-toxic, making it a major agricultural film product in my country. With the addition of additives such as anti-aging agents, anti-drip and anti-fogging agents, and heat-insulating agents, it can adapt to various greenhouse film requirements. However, its lifespan is limited to a maximum of 18 months, and anti-drip and anti-fogging agents cannot be added internally but can only be applied to the film surface through impregnation, making them easily scratched off and thus losing their anti-drip and anti-fogging function. EVA greenhouse film is a new agricultural film material used in recent years. It has better heat preservation, light transmission and weather resistance than PVC or PE greenhouse film. It can be used continuously for 2 years, does not deform before aging, is easy to recycle and does not easily cause soil or environmental pollution.

[0003] However, all three types of greenhouse films mentioned above are produced using a blow molding process. Raw material granules are plasticized and extruded to form tube blanks, which are then blown into shape. Therefore, these three types of films share common defects: low strength, poor puncture resistance, low tear strength, and brittleness below zero degrees Celsius. They are easily damaged by severe winter weather common in northern China, such as strong winds and hail, causing damage to crops in greenhouses and significant economic losses for farmers. In Tibet, one greenhouse using these films was blown apart by strong winds in a single year and had to be replaced four times. Furthermore, this blow molding process makes it difficult to achieve long-term anti-fogging properties. Due to the limitations of the process, the addition of additives is very restrictive, generally only lasting 4-6 months. Therefore, users must replace the plastic greenhouse film annually, with replacement costs exceeding 3,000 yuan per mu (approximately 0.16 acres), resulting in both material waste and economic losses. Finally, the biggest problem with these three types of greenhouse films is their inability to diffuse sunlight, causing direct sunlight exposure to high temperatures, which can scorch the leaves of crops and shorten their fruiting period.

[0004] Furthermore, the carrier resin for existing anti-fogging masterbatches is ethylene-vinyl acetate copolymer (EVA), which costs 2 to 5 times more than polyethylene (PE). Its processing performance is relatively poor, and it disperses unevenly during casting processes, resulting in significant variations in film thickness. The anti-fogging function quickly disappears in thinner areas. Additionally, EVA resin is not heat-resistant, with a maximum processing temperature of 230°C. It is difficult to completely clean it during mold changes, and the resin residue in the screw and die will carbonize, continuously producing clumps of paste during production, causing film breakage and significant waste. Moreover, traditional inner surface coating processes require secondary coating, reducing production efficiency and wasting raw materials and energy. Summary of the Invention

[0005] The purpose of this invention is to solve the aforementioned problems existing in the prior art, and to propose a greenhouse film, its preparation method, and its application. The greenhouse film formulation uses polyethylene (PE) as the carrier resin in its anti-fogging masterbatch, effectively solving the problems associated with ethylene-vinyl acetate copolymer (EVA) carriers. Furthermore, the processing temperature of polyethylene (PE) can be increased to 260-300 degrees Celsius, increasing production line speed while significantly improving the uniformity of film thickness, effectively reducing production costs. In its preparation method, co-extrusion using two extruders is completed in one step, improving production efficiency while reducing raw material loss and energy waste. The greenhouse film prepared using this invention, when applied in greenhouses, can increase the frequency of film replacement from one year to more than five years, reducing the environmental impact of plastic film recycling.

[0006] The technical solution of this invention is:

[0007] A greenhouse film is composed of a woven layer and a coating layer. The woven layer is formulated with the following components in parts by weight: 88.8-96.95 parts of high-density polyethylene, 0-5 parts of low-density polyethylene, 0.05-0.2 parts of graphene, and 3-6 parts of anti-aging concentrated masterbatch.

[0008] The woven layer comprises 88.8 to 96.95 parts of high-density polyethylene, for example, 88.8, 89.8, 90.8, 91.8, 92.8, 93.8, 94.5, 95, 95.5, 96, 96.5, or 96.95 parts, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0009] The woven layer includes 0 to 5 parts of low-density polyethylene, for example, 0 parts, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0010] The woven layer includes 0.05 to 0.2 parts of graphene, for example, 0.05 parts, 0.1 parts, 0.15 parts or 0.2 parts, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0011] The woven layer includes 3 to 6 parts of anti-aging concentrated masterbatch, for example, 3, 4, 5 or 6 parts, but not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0012] Adding anti-aging concentrated masterbatch UV-0609 (acidic, pH value less than 7) to the woven layer formula instead of anti-aging concentrated masterbatch UV-0601 (alkaline, pH value greater than 7) can improve the greenhouse film's resistance to pesticide aging and ensure that the greenhouse film has a service life of more than 5 years.

[0013] Add 0-5 parts of low-density polyethylene to the formula of the braided layer (i.e., the production formula of transparent flat yarn) to improve the flexibility of the flat yarn. Add 3-6 parts of anti-aging concentrated masterbatch (acidic, pH value less than 7) to improve the ability of the greenhouse film to resist pesticide aging and ensure that the service life of the greenhouse film reaches more than 5 years. Add 0.05-0.2 parts of graphene to improve the strength and toughness of the flat yarn from 4.3g / D to 5.3g / D, while controlling the heat shrinkage rate to within 2.5%.

[0014] The coating layer consists of an inner surface layer and an outer surface layer. The outer surface layer is formulated with the following components in parts by weight: 33.8 to 46.95 parts of low-density polyethylene, 50 to 60 parts of linear low-density polyethylene, 0.05 to 0.2 parts of graphene, and 3 to 6 parts of anti-aging concentrated masterbatch.

[0015] The outer layer comprises 33.8 to 46.95 parts of low-density polyethylene, for example, 33.85, 33.9, 33.95, 34.8, 34.85, 34.9, 34.95, 35.8, 35.85, 35.9, 35.95, 36.8, 36.85, 36.9, 36.95, 41.95, or 46.95 parts, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0016] The outer layer comprises 50 to 60 parts of linear low-density polyethylene, for example, 50 parts, 52 parts, 54 parts, 55 parts, 56 parts, 57 parts or 60 parts, etc., but not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0017] The outer layer includes 0.05 to 0.2 parts of graphene, for example, 0.05 parts, 0.1 parts, 0.15 parts or 0.2 parts, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0018] The outer layer anti-aging concentrated masterbatch is 3 to 6 parts, for example, 3 parts, 4 parts, 5 parts or 6 parts, but not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0019] The inner surface layer consists of an inner inner surface layer and an outer inner surface layer, which are obtained by co-extrusion in one step using two extruders. The formulation of the inner inner surface layer is the same as that of the outer surface layer. The formulation of the outer inner surface layer includes the following components in parts by weight: 15-20 parts of low-density polyethylene, 18.7-26.9 parts of linear low-density polyethylene; 50-60 parts of polydimethylsiloxane anti-fogging masterbatch, 3-6 parts of anti-aging concentrated masterbatch, and 0.1-0.3 parts of color masterbatch 6580. While ensuring the anti-fogging effect, its antibacterial properties are improved.

[0020] The outer and inner surface layers comprise 15 to 20 parts of low-density polyethylene, for example, 15, 16, 17, 18, 18.5, 19, 19.5 or 20 parts, but are not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0021] The inner and outer surface layers comprise 18.7 to 26.9 parts of linear low-density polyethylene; for example, it can be 18.7, 19.7, 19.8, 19.9, 20.7, 20.8, 20.9, 21.7, 21.8, 21.9, or 26.9 parts, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0022] The outer and inner surface layers include 50 to 60 parts of polydimethylsiloxane antifogging masterbatch, for example, 50 parts, 55 parts or 60 parts, but not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0023] The outer and inner surface layers include 3 to 6 parts of anti-aging concentrated masterbatch, for example, 3 parts, 4 parts, 5 parts or 6 parts, but not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0024] The outer and inner surface layers include 0.1 to 0.3 parts of color masterbatch, for example, 0.1 parts, 0.15 parts, 0.2 parts, 0.25 parts, or 0.3 parts, but are not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0025] The high-density polyethylene is selected from HDPE 6094 or HDPE 7750Z; the low-density polyethylene is selected from LC7ALDPE or 801YY LDPE; and the linear low-density polyethylene is selected from any one or two of 8320 / 3470LLDPE and 488 / 5815LLDPE.

[0026] Adding a certain amount of polydimethylsiloxane-containing anti-fogging masterbatch to the inner layer of the above-mentioned coating can ensure that the greenhouse film will not fog or drip within 5 years. Simultaneously, the carrier of the anti-fogging masterbatch has been improved by changing the EVA carrier to a PE carrier. This allows for a higher production process temperature of 260–300℃, preferably 280℃, during coating, making product production easier to implement and reducing production costs.

[0027] The polydimethylsiloxane anti-fogging masterbatch includes 8-10 parts of polydimethylsiloxane, 5-7 parts of anti-aging agent, 45-55 parts of low-density polyethylene, and 30-40 parts of linear low-density polyethylene.

[0028] The polydimethylsiloxane antifogging masterbatch includes 8 to 10 parts of polydimethylsiloxane, for example, 8, 9 or 10 parts, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0029] The polydimethylsiloxane antifogging masterbatch includes 5 to 7 parts of anti-aging agent, for example, 5, 6 or 7 parts, but not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0030] The polydimethylsiloxane antifogging masterbatch includes 45 to 55 parts of low-density polyethylene, for example, 45 parts, 47 parts, 49 parts, 50 parts, 52 parts or 55 parts, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0031] The polydimethylsiloxane antifogging masterbatch includes 30 to 40 parts of linear low-density polyethylene, for example, 30, 31, 32, 33, 35, 36, 37.5, 38, 39 or 40 parts, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0032] Furthermore, the components of the anti-aging concentrated masterbatch include long-acting antioxidants, short-acting antioxidants, and hindered amine light stabilizers. The anti-aging concentrated masterbatch is selected from either UV-G0609 or UV-G0601, with UV-G0609 being preferred.

[0033] Long-acting antioxidants in anti-aging concentrated masterbatches can prevent the resin from being oxidized by the external environment during product use, while short-acting antioxidants can prevent resin oxidation caused by high temperatures during the manufacturing process.

[0034] Furthermore, the anti-aging agent is selected from either 770 or 622.

[0035] Furthermore, the greenhouse film is composed of a woven layer and a coating layer laminated to both sides of the woven layer. The woven layer is located between the two coating layers, and the coating layer is laminated to the surface of the woven layer by coating. The coating layer includes an inner surface layer and an outer surface layer. The inner surface layer is composed of an inner inner surface layer close to the woven layer and an outer inner surface layer close to the outer surface layer.

[0036] In the composite structure of the greenhouse film mentioned above, the woven layer is used as a reinforcing layer, which effectively solves the problems of traditional greenhouse films being not puncture-resistant and having low tear strength.

[0037] The greenhouse film protected by this invention has a multi-layer composite structure. Corresponding formulations are developed based on the function of each layer. In the preparation process, high-density polyethylene and low-density polyethylene are stretched into high-strength, high-transparency flat filaments using a drawing machine, with the addition of anti-aging concentrated masterbatch and graphene. These filaments are then woven into woven layers using a circular loom, resulting in a fabric with high strength in both warp and weft directions, achieving a tensile strength of over 350N, which is more than 2.5 times that of ordinary greenhouse films. Transparent low-density polyethylene and linear low-density polyethylene are coated on both sides of the woven layers, resulting in a high-strength transparent woven film. A certain amount of polydimethylsiloxane anti-fogging masterbatch is added to the coating layer to ensure long-lasting anti-fogging function.

[0038] This invention also provides a method for preparing a greenhouse film, comprising the following steps:

[0039] (1) Wire drawing: Weigh the raw materials according to the formula of the braided layer, mix HDPE and LDPE with graphene and anti-aging concentrated masterbatch evenly, feed the evenly mixed raw materials into the extruder, heat and plasticize them by the screw, and extrude the molten material into a plastic film. After water cooling, cut it into filaments and stretch them into flat filaments by setting a draw ratio of 5 to 8. The flat filaments are heat set and the heat shrinkage rate is controlled within 2.5%.

[0040] The thermal shrinkage rate in existing technologies is generally around 3.5%. After adding graphene, the thermal shrinkage rate is controlled within 2.5%, ensuring that the finished product is not prone to shrinkage during use and has high stability.

[0041] (2) Weaving: Weave the flat yarns into a weaving layer according to the set weaving density of 4×3 or 5×3 to ensure that the warp and weft of the fabric are uniform, flat and have consistent tension.

[0042] (3) Coating: Weigh LDPE, LLDPE, graphene and anti-aging concentrated masterbatch according to the formula of the outer layer, mix them evenly with a mixer and feed them into the feed cylinder of the extruder. After being heated and extruded by the extruder, they enter the T-die to form a transparent cast film. After being extruded by the silicone roller, back pressure roller and cooling roller, they are pasted onto the outer layer of the braided layer. Weigh LDPE, LLDPE, graphene and anti-aging concentrated masterbatch according to the formula of the inner and outer layers, mix them evenly with a mixer and feed them into the feed cylinder of extruder A. Weigh LDPE, LLDPE, anti-aging concentrated masterbatch, color masterbatch and anti-fogging masterbatch containing polydimethylsiloxane according to the formula of the inner and outer layers. Mix them evenly with a mixer and feed them into the feed cylinder of extruder B. Start extruder A and extruder B at the same time. The evenly mixed raw materials are heated and extruded by the extruder and enter the same T-die to obtain a cast film composed of two formulas. After being extruded by the silicone roller, back pressure roller and cooling roller, it is pasted onto the inner layer of the braided layer, and the inner surface layer with anti-fogging function is completed in one step.

[0043] One-time extrusion coating breaks through the cumbersome process that previously required two coatings, improving production efficiency and reducing production costs;

[0044] (4) Heat sealing: The greenhouse film obtained in step (3) is sent into a heat sealing machine for bonding. The heat sealing temperature is set to 600-700℃ and the production line speed is 30-40 meters.

[0045] Furthermore, the temperature during heating and plasticizing in step (1) is 230–280°C, at which the material reaches a molten state; the water temperature during water cooling is 30–45°C.

[0046] Furthermore, the coating temperature in step (3) is 190–300°C, at which the material reaches a molten state; the coating speed is 35–50 m / min.

[0047] The present invention also provides the application of the above-mentioned greenhouse film in greenhouses.

[0048] The beneficial effects of this invention are:

[0049] The greenhouse film provided by this invention is a new type of agricultural greenhouse film. The woven film within it is a greenhouse woven film developed by drawing on advanced technologies from Israel, Japan, and South Korea, and combining them with the actual needs of domestic greenhouse films. The greenhouse film of this invention has the following advantages:

[0050] (1) Its unique multi-layer structure can transform the light inside the greenhouse into diffused light, ensuring that the crops inside the greenhouse receive more light. At the same time, it avoids the scorching of the leaves of crops inside the greenhouse caused by direct sunlight caused by ordinary greenhouse film, and prolongs the fruiting period of crops inside the greenhouse while increasing yield. The harvesting period of this product is 1-2 weeks earlier than that of ordinary greenhouse film, and the fruiting period is extended by nearly a month. The woven layer plays a role in refracting light, which is more conducive to crop growth. At the same time, due to the presence of diffused light, the amount of antifungal pesticides used is greatly reduced.

[0051] (2) It has good strength. The tensile and tear strength of the woven layer is more than 2.5 times that of ordinary film. It can avoid being blown by strong winds or hit by hail, effectively defend against the effects of severe weather, prevent the phenomenon of film breakage, and can withstand personnel walking and working on the roof in actual use.

[0052] (3) The anti-fogging masterbatch used in the coating process contains polydimethylsiloxane, which maintains the anti-fogging effect for a long time, and the anti-fogging function has a long service life and a warranty period of up to five years. This increases the frequency of replacing the film from 1 year to more than 5 years, avoiding the need to replace the greenhouse film every year and effectively reducing the user's operating costs.

[0053] (4) The outer side of the greenhouse film is coated with graphene, which can effectively remove dust by rain or water gun, ensuring light transmittance.

[0054] (5) After 5 years of use, the greenhouse film product can still retain more than 80% of its strength, which ensures that it can be recycled and reused; it reduces the amount of waste film to be recycled and processed, saves energy and reduces emissions, and reduces the adverse environmental impact caused by plastic degradation. Attached Figure Description

[0055] Figure 1 This is a schematic diagram of the structure of the braided layer provided by the present invention. Detailed Implementation

[0056] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0057] To further understand the present invention, it will be further described in conjunction with the accompanying drawings and embodiments.

[0058] Unless otherwise specified, the raw materials used in the following examples are either commercially available in China or imported.

[0059] The greenhouse film provided by this invention consists of a woven layer and a coating layer laminated to both sides of the woven layer. The woven layer is located between the two coating layers, and the coating layers are laminated to the surface of the woven layer by coating. The coating layer includes an inner surface layer and an outer surface layer. The inner surface layer consists of an inner inner surface layer close to the woven layer and an outer inner surface layer close to the outer surface layer. Figure 1 The diagram shown is a schematic representation of the structure of a high-strength transparent woven layer.

[0060] Example 1

[0061] This embodiment provides a greenhouse film, the formulation of each layer of which is shown in Table 1. The preparation method includes the following steps:

[0062] Fiber mixing: Weigh the raw materials according to the formula of the braided layer, add 0.1% graphene and 5% anti-aging concentrated masterbatch UV-G0609 to 90.9% HDPE 7750Z and 4.0% 801YYLDPE, pour them into different hoppers, and then use a vacuum feeder to automatically suck the particles into a high-speed mixer and mix them evenly (4.0% LDPE is added to increase the flexibility of the raw yarn, and acidic UV-G0609 with stronger pesticide resistance is used instead of alkaline UV-G0601).

[0063] Filament drawing: The uniformly mixed raw materials are fed into an extruder and heated and plasticized by the screw at a temperature between 230 and 280°C. At this temperature, the material reaches a molten state and is extruded from the die head to form a plastic film. After water cooling (water temperature at 44°C), the film is cut into filaments by a blade. The filaments are then stretched and formed by an oven or stretching plate with a set draw ratio of 7.2. The flat filaments are then heat-set, with the heat shrinkage rate controlled to be within 2.0%. Finally, they are wound up by a winding machine.

[0064] Weaving: Flat yarns are woven into a woven layer by a circular loom. The weaving density is set to 5×3 mesh / square inch. At the same time, it is ensured that the warp and weft of the fabric are even, flat, and have consistent tension. In particular, the weft threads are ensured to be flat and without folds to ensure transparency (the weaving density is changed from 4×3 mesh / square inch to 5×3 mesh / square inch to make the woven layer stronger, the fabric surface flatter, and reduce edge folds).

[0065] Coating: According to the outer layer formula, weigh 34.90% 801YY LDPE, 30% 8320 LLDPE, 30% 488 / 5815 LLDPE, 0.1% graphene, and 5% anti-aging concentrated masterbatch UV-G0609. Mix them evenly with a mixer and feed them into the extruder feed cylinder. After being heated and extruded by the extruder, it enters the T-die to form a transparent cast film. After being extruded by silicone rollers, back pressure rollers, and cooling rollers, it is adhered to the outer layer of the braided layer. According to the inner and outer layer formula, weigh 34.90% 801YY LDPE, 30% 8320 LLDPE, 30% 488 / 5815 LLDPE, 0.1% graphene, and 5% anti-aging concentrated masterbatch UV-G0609. Mix them evenly with a mixer and feed them into the A extruder feed cylinder. According to the outer and inner layer formula, weigh 20.0% 801YY... LDPE, 24.8% 8320LLDPE, 5% anti-aging concentrated masterbatch UV-G0609, 0.2% color masterbatch 6580, and 50% anti-fogging masterbatch containing polydimethylsiloxane are mixed evenly in a mixer and then fed into the feeding cylinder of extruder B. Extruders A and B are started simultaneously. The raw materials are heated and extruded separately through the extruders and then fed into the same T-die to produce a cast film composed of two formulations. This film is then pressed through silicone rollers, back pressure rollers, and cooling rollers and adhered to the inner layer of the braided layer. The inner surface layer with anti-fogging function is completed in one step; the coating temperature is set to 190-280℃ and the speed is 50 m / min. At this temperature, the material reaches a molten state (replacing 30% 8320 LLDPE with 30% 488 / 5815 LLDPE enhances the toughness of the greenhouse film; the anti-fogging agent is adjusted from 60% to 50%; the coating temperature is reduced from 295℃ to 280℃; the cooling water temperature is reduced from 25℃ to 15℃; and the extrusion speed is increased from 30 m / min to 50 m / min).

[0066] Heat sealing: The greenhouse film after the coating step is sent into the heat sealing machine for bonding. The heat sealing temperature is set to 700℃ and the production line speed is 40 meters. Finally, the width and length of the new type of greenhouse film required for agricultural greenhouse covering are heat sealed and cut.

[0067] Table 1. Formulation composition (parts) of greenhouse films in Examples 1-4

[0068]

[0069]

[0070] Example 2

[0071] This embodiment provides a greenhouse film, the composition of each layer of which is shown in Table 1 above. The preparation method of this film differs from that of Embodiment 1 in that the composition of the formula is different and the weaving density is 4×3 mesh / square inch; other steps are the same as in Embodiment 1.

[0072] Example 3

[0073] This embodiment provides a greenhouse film, the composition of each layer of which is shown in Table 1 above. The preparation method of this film differs from that of Embodiment 1 in that the composition of the formula is different and the weaving density is 4×3 mesh / square inch; other steps are the same as in Embodiment 1.

[0074] Example 4

[0075] This embodiment provides a greenhouse film, the composition of each layer of which is shown in Table 1 above. The preparation method of this film differs from that of Embodiment 1 in that the composition of the formula is different and the weaving density is 4×3 mesh / square inch; other steps are the same as in Embodiment 1.

[0076] Experimental Example 1

[0077] The performance of the greenhouse film prepared in Example 1 of the present invention was tested, and the test results are shown in Table 2 below.

[0078] Table 2 Comparison of various performance test data of greenhouse film, greenhouse PO film, and greenhouse PVC film.

[0079]

[0080]

[0081] Conclusion: The greenhouse film prepared using the method of this invention has a tensile strength 2.5–3.0 times that of PO and PVC greenhouse films, a tear strength 3–5 times that of PO greenhouse films, and 64–65 times that of PVC greenhouse films. In the anti-aging test (QUVA 340nm 500 hours), it retains 90% of its strength after 5 years of use. The PPED ultraviolet transmittance is 34.653 μmol / m². 2 / s, the lowest among all greenhouse films, avoids scorching of crops inside the greenhouse by ultraviolet rays, and effectively improves the production period and yield of crops inside the greenhouse.

[0082] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, alterations, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A greenhouse tunnel film, characterized in that, The woven layer and the coating film layer, the formula of the woven layer includes the following components by weight: high-density polyethylene 88.8-96.95 parts, low-density polyethylene 0-5 parts, graphene 0.05-0.2 parts, anti-aging concentrated master batch 3-6 parts; The coating film layer is composed of an inner surface layer and an outer surface layer, the formula of the outer surface layer includes the following components by weight: low-density polyethylene 33.8-46.95 parts, linear low-density polyethylene 50-60 parts, graphene 0.05-0.2 parts, anti-aging concentrated master batch 3-6 parts; The inner surface layer is composed of an inner inner surface layer and an outer inner surface layer, the formula of the inner inner surface layer is consistent with that of the outer surface layer, and the formula of the outer inner surface layer includes the following components by weight: low-density polyethylene 15-20 parts, linear low-density polyethylene 18.7-26.9 parts, anti-fogging drop master batch containing polydimethylsiloxane 50-60 parts, anti-aging concentrated master batch 3-6 parts, color master batch 6580 0.1-0.3 parts; The high-density polyethylene is selected from HDPE 6094 or HDPE 7750Z; the low-density polyethylene is selected from LC7ALDPE or 801YY LDPE; and the linear low-density polyethylene is selected from 8320 LLDPE and 488 / 5815 LLDPE; The anti-fogging drop master batch containing polydimethylsiloxane includes polydimethylsiloxane 8-10 parts, anti-aging agent 5-7 parts, low-density polyethylene 45-55 parts, and linear low-density polyethylene 30-40 parts; The preparation method of the greenhouse film includes the following steps: (1) drawing, according to the formula of the woven layer, the raw materials are weighed, the HDPE, LDPE and anti-aging concentrated master batch with graphene are uniformly mixed, the uniformly mixed raw materials are sent into an extruder, the molten materials are extruded into plastic film, and then cut into embryonic filaments after water cooling, and the embryonic filaments are stretched into flat filaments by setting a 5-8 times draft ratio, and the flat filaments are heat set, and the heat shrinkage rate is controlled to be within 2.5%; (2) weaving, the flat filaments are woven into a woven layer according to the set weaving density of 4*3 or 5*3 meshes per square inch, so that the warp and weft of the cloth surface are uniform, flat and consistent in tension; (3) coating, according to the formula of the outer surface layer, the LDPE, LLDPE, graphene and anti-aging concentrated master batch are weighed, stirred uniformly by a mixer, and then sent into an extruder feeding cylinder, extruded by the extruder, and then formed into a transparent casting film through a T-shaped die, and then extruded through a silica gel roller, a back pressure roller and a cooling roller to be pasted on the outer surface of the woven layer to form the outer surface layer; According to the formula of the inner surface layer, LDPE, LLDPE, graphene and anti-aging concentrated master batch are weighed, mixed uniformly by a mixer and then fed into a feeding cylinder of an A extruder, according to the formula of the outer and inner surface layer, LDPE, LLDPE, anti-aging concentrated master batch, color master batch and dimethicone-containing anti-fog drop master batch are weighed, mixed uniformly by a mixer and then fed into a feeding cylinder of a B extruder, the A extruder and the B extruder are started at the same time, the mixed raw materials are respectively extruded by the extruders after being heated, and then enter a same T-shaped die to prepare a cast film composed of two formulas, and then the cast film is adhered to the inner layer of the woven layer after being extruded by a silica gel roller, a back pressure roller and a cooling roller, and the inner surface layer with the anti-fog drop function is completed at one time. (4) Heat sealing, the greenhouse film prepared in step (3) is sent into a heat sealing machine for bonding, the heat sealing temperature is set to 600-700 °C, the production line speed is 30-40 m, and heat sealing is performed.

2. The greenhouse film according to claim 1, characterized in that, The anti-aging agent is selected from any one of 770 and 622.

3. The greenhouse film according to claim 1, characterized in that, The temperature during heating and plasticizing in step (1) is 230-280 °C, at which the material reaches a molten state; and the water temperature during water cooling is 30-45 °C.

4. The greenhouse film according to claim 3, characterized in that, The film coating temperature in step (3) is 190-300 °C, at which the material reaches a molten state; and the film coating speed is 35-50 m / min.

5. Application of the greenhouse film according to any one of claims 1-4 in a greenhouse.

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