A film capable of regulating ultraviolet light, and preparation method and application thereof

Abstract

The present invention belongs to the field of materials, and specifically discloses a film capable of regulating ultraviolet rays, a preparation method thereof and an application thereof; the film comprises a heat-insulating layer, an ultraviolet absorption layer and a heat-insulating layer which are stacked in sequence; the ultraviolet absorption layer comprises the following components in mass percentage: 0.1-1% of a UVA ultraviolet absorber, 0.5-5% of a UVB ultraviolet absorber, and 94-99.4% of a resin matrix. The film of the present invention introduces a UVA ultraviolet absorber and a UVB ultraviolet absorber into the ultraviolet absorption layer, and partially absorbs the ultraviolet rays in the sunlight to achieve regulation of the light intensity of the UVA ultraviolet rays and the UVB ultraviolet rays passing through the film, thereby obtaining an ultraviolet environment suitable for plant growth, so that the plant can effectively utilize the ultraviolet rays and thus increase the content of nutrients in the fruit, such as anthocyanins and quercetin.

Description

Technical Field

[0001] The invention belongs to the field of materials, and in particular relates to a film capable of regulating ultraviolet rays, a preparation method and an application thereof. Background Art

[0002] Strong ultraviolet rays will cause the plant's morphology to become special during growth, and the plant will be short, the leaves will shrink, and the hair will gradually develop. As the internal accumulation of the plant increases, its chlorophyll is also increasing, making the color of the plant more colorful. Long ultraviolet rays can also stimulate and promote plant growth, and can continuously increase the yield of plants, prompting them to continuously synthesize proteins, sugars, acids, etc. required for growth. Exposing seeds to long ultraviolet rays for a long time can increase their germination rate. Short ultraviolet rays can effectively prevent plants from growing too tall during growth, and can sterilize and disinfect plants, reducing the occurrence of diseases and pests. The effect of ultraviolet rays on plant growth is complex and multifaceted, and the specific effect depends on the wavelength, intensity, exposure time and type of plant.

[0003] Ultraviolet rays are usually divided into three categories: UV-A (315-400nm), UV-B (280-315nm) and UV-C (100-280nm). In the natural environment, about 6% of sunlight is ultraviolet radiation, almost all short-wave ultraviolet radiation (UVC) and most (98%) of medium-wave ultraviolet radiation (UVB) are intercepted by the ozone layer, and the main ultraviolet radiation that reaches the earth's surface is long-wave ultraviolet radiation (UVA) and a small amount of UVB. In the ultraviolet radiation near the equator, UVA accounts for about 95% and UVB accounts for about 5%.

[0004] An appropriate amount of UV-A can promote plant photosynthesis and increase plant biomass and chlorophyll content. Secondly, UV-A can also induce secondary metabolites and promote the synthesis of secondary metabolites in plants, such as flavonoids and anthocyanins, which help improve the plant's ability to resist ultraviolet rays and antioxidants. UV-B radiation can damage the DNA of plants, affect cell division and growth, and lead to growth retardation or abnormal development. In addition, excessive UV-B will inhibit the expansion of plant leaves, reduce photosynthesis efficiency, and thus affect growth. However, a large number of studies have shown that under UV-B radiation, the content of UV-B absorbing substances in plant leaves will increase, and this is considered to be a protective response of plants to UV-B radiation. The increase in flavonol content under enhanced UV-B radiation is closely related to the increase in phenylalanine lyase (PAL) activity or the accelerated synthesis of this enzyme. Under UV-B radiation, the mRNA transcription levels of phenylphenylketone synthase (CHS) and phenylalanine lyase (PAL) increase, that is, UV-B radiation can regulate the pigment metabolism of plants at the gene expression level. Therefore, an appropriate amount of UV-B can induce plants to produce protective secondary metabolites and improve their ability to resist diseases and pests. The prior art also attempts to introduce ultraviolet absorbers into agricultural films. The introduced ultraviolet absorbers are generally used to absorb UVB ultraviolet rays in sunlight, with the purpose of slowing down the aging rate of polymer materials in agricultural films and extending the service life of agricultural films. Summary of the invention

[0005] In order to overcome the problems existing in the prior art, one of the objectives of the present invention is to provide a film.

[0006] A second object of the present invention is to provide a method for preparing a thin film.

[0007] A third object of the present invention is to provide an application of a film in the field of plant cultivation.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] The first aspect of the present invention provides a film, comprising a heat insulating layer, an ultraviolet absorption layer and a thermal insulation layer stacked in sequence; the ultraviolet absorption layer comprises the following components in mass percentage: 0.1-1% UVA ultraviolet absorber, 0.5-5% UVB ultraviolet absorber, and 94-99.4% resin matrix.

[0010] In the present invention, the mass percentage of the UVA ultraviolet absorber is 0.1-1%, for example, it can be selected from 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1%. The UVA ultraviolet absorber introduced into the ultraviolet absorption layer with the above mass percentage can absorb the UVA in the sunlight, avoid too much UVA content passing through the film, thereby affecting the growth of plants. In addition, the use of the above content of UVA ultraviolet absorber can promote the synthesis of some nutrients in plants, especially anthocyanins, increase the content of anthocyanins in fruits, and further improve the nutritional value of fruits.

[0011] Preferably, the UVA ultraviolet absorber is selected from at least one of carbon quantum dots, nano titanium dioxide, nano zinc oxide, and avobenzone.

[0012] In the present invention, the mass percentage of the UVB ultraviolet absorber is 0.5-5%, for example, it can be selected from 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%. The UVB ultraviolet absorber introduced into the ultraviolet absorption layer with the above mass percentage can absorb the UVB in the sunlight, avoid too much UVB content passing through the film, thereby affecting the growth of plants. In addition, the use of the above content of UVB ultraviolet absorber can promote the synthesis of some nutrients in plants, especially quercetin, increase the content of quercetin in fruits, and further improve the nutritional value of fruits.

[0013] Preferably, the UVB ultraviolet absorber is selected from at least one of 2,4-dihydroxybenzophenone (UV-0), 2-hydroxy-4-methoxybenzophenone (UV-9), 2-hydroxy-4-n-octyloxybenzophenone (UV-531), 2-(2'-hydroxy-5'-methylphenyl)benzotriazole (UV-P), 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole (UV-326), 2-(2'-hydroxy-3',5'-di-tert-phenyl)-5-chlorobenzotriazole (UV-327), 2-(2-hydroxy-3,5-dit-pentylphenyl)benzotriazole (UV-328), and 2-(2'-hydroxy-4'-benzoylphenyl)-5-chloro-2H-benzotriazole (UV-366).

[0014] Preferably, the thermal insulation layer contains a resin matrix and a thermal insulation material; the mass of the thermal insulation material is 0.5-20% of the total mass of the thermal insulation layer. For example, the mass percentage of the thermal insulation material can be selected from 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, and 20%.

[0015] Preferably, the thermal insulation material is selected from at least one of tin oxide, aluminum oxide, zirconium oxide and magnesium oxide. The thermal insulation material in the present invention is a material with low thermal conductivity.

[0016] Preferably, the particle size of the thermal insulation material is 10 to 150 nm. If the particle size of the thermal insulation material is too large, it will affect data such as light transmittance and haze.

[0017] Preferably, the thermal insulation layer contains a resin matrix and a thermal insulation material; the mass of the thermal insulation material is 0.5-20% of the total mass of the thermal insulation layer. For example, the mass percentage of the thermal insulation material can be selected from 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, and 20%.

[0018] Preferably, the thermal insulation material is selected from at least one of aluminum silicate, tourmaline and hydrotalcite.

[0019] Preferably, the resin matrix is ​​selected from at least one of polyethylene, nylon, polyvinyl alcohol, polypropylene, EPDM rubber, CTC resin, and maleic anhydride. The resin matrix in the present invention can also be selected from other resin matrices commonly used in agricultural mulch films in the prior art.

[0020] Preferably, the thickness of the thermal insulation layer is 5 to 200 μm, for example, can be selected from 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm.

[0021] Preferably, the thickness of the ultraviolet absorption layer is 1 to 150 μm, for example, can be selected from 1 μm, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm.

[0022] Preferably, the thickness of the thermal insulation layer is 1 to 180 μm; for example, it can be selected from 1 μm, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, and 180 μm.

[0023] Preferably, at least one of the heat insulating layer, the thermal insulation layer and the ultraviolet absorption layer further contains an auxiliary agent.

[0024] Preferably, the thermal insulation layer contains a resin matrix, a thermal insulation material and an auxiliary agent.

[0025] Preferably, the thermal insulation layer contains a resin matrix, thermal insulation materials and additives.

[0026] Preferably, the ultraviolet absorption layer contains a resin matrix, a UVA ultraviolet absorber, a UVB ultraviolet absorber and an auxiliary agent.

[0027] Preferably, the auxiliary agent is selected from at least one of a lubricant, a light stabilizer, an antioxidant, a solubilizer, and a coupling agent.

[0028] The second aspect of the present invention provides a method for preparing the film according to the first aspect of the present invention, comprising the following steps:

[0029] The raw materials of the heat insulating layer, the ultraviolet absorption layer and the thermal insulation layer are mixed respectively, and then extruded by using a three-layer co-extrusion device to obtain the film.

[0030] The third aspect of the present invention provides the use of the film described in the first aspect of the present invention in the field of plant cultivation.

[0031] The beneficial effect of the present invention is that the film of the present invention introduces UVA ultraviolet absorber and UVB ultraviolet absorber into the ultraviolet absorption layer, and partially absorbs ultraviolet rays in sunlight to achieve regulation of the light intensity of UVA ultraviolet rays and UVB ultraviolet rays passing through the film, thereby obtaining an ultraviolet environment suitable for plant growth, enabling plants to effectively utilize ultraviolet rays and thereby increasing the content of nutrients in fruits, such as anthocyanins and quercetin.

[0032] The film of the present invention is prepared by a three-layer co-extrusion method, the preparation method is simple and easy to operate, and is suitable for mass industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the structure of the agricultural film in Examples 1 and 2. DETAILED DESCRIPTION

[0034] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples, but the implementation and protection of the present invention are not limited thereto. It should be noted that if there are processes that are not particularly described in detail below, they can be implemented or understood by those skilled in the art with reference to the prior art. The reagents or instruments used that do not indicate the manufacturer are all conventional products that can be purchased commercially.

[0035] Example 1

[0036] like Figure 1 As shown, this example provides an agricultural film with adjustable ultraviolet rays, including a heat insulation layer, an ultraviolet absorption layer and a thermal insulation layer stacked in sequence; the heat insulation layer is the outermost layer directly exposed to sunlight.

[0037] The heat insulating layer is composed of 1% by mass of tin oxide and 99% by mass of polyethylene, and the thickness of the heat insulating layer is 20 μm.

[0038] The ultraviolet absorption layer is composed of 0.1% by mass of carbon quantum dots (UVA absorber), 1% by mass of 2,4-dihydroxybenzophenone (UV-0) (UVB absorber), and 98.9% by mass of polyethylene, and has a thickness of 30 μm.

[0039] The heat-insulating layer is composed of 1% by mass of aluminum silicate and 99% by mass of polyethylene, and has a thickness of 30 μm.

[0040] Example 2

[0041] like Figure 1 As shown, this example provides an agricultural film with adjustable ultraviolet rays, including a heat insulation layer, a UV absorption layer and a thermal insulation layer stacked in sequence; the heat insulation layer is the outermost layer directly exposed to sunlight.

[0042] The heat insulation layer is composed of 5% by mass of zirconium oxide and 95% by mass of polyethylene, and has a thickness of 30 μm.

[0043] The ultraviolet absorption layer is composed of 95.5% by mass of polyethylene, 0.5% by mass of nano zinc oxide (UVA absorber), and 4% by mass of 2-hydroxy-4-n-octyloxybenzophenone (UV-531) (UVB absorber), and has a thickness of 30 μm.

[0044] The heat-insulating layer is composed of 7% by mass of hydrotalcite and 93% by mass of polyethylene, and has a thickness of 30 μm.

[0045] Comparative Example 1

[0046] This example provides an agricultural film, comprising a heat-insulating layer, a blank layer and a thermal insulation layer stacked in sequence; the heat-insulating layer is the outermost layer directly exposed to sunlight.

[0047] The heat insulating layer is composed of 1% by mass of tin oxide and 99% by mass of polyethylene, and the thickness of the heat insulating layer is 20 μm.

[0048] The blank layer is made of polyethylene and has a thickness of 30 μm.

[0049] The heat-insulating layer is composed of 1% by mass of aluminum silicate and 99% by mass of polyethylene, and has a thickness of 30 μm.

[0050] The agricultural films in Examples 1 to 3 and Comparative Example 1 can be prepared by referring to the following preparation method, specifically:

[0051] (1) fully mixing the raw materials for preparing the heat insulation layer, the ultraviolet absorption layer, and the thermal insulation layer to obtain a heat insulation layer premix, an ultraviolet absorption layer premix, and a thermal insulation layer premix, respectively;

[0052] (2) Add the heat insulation layer premix, the ultraviolet absorption layer premix and the thermal insulation layer premix into a co-extruder, and perform three-layer co-extrusion to obtain the agricultural films in Examples 1 to 3 and Comparative Example 1.

[0053] Performance Test:

[0054] The tensile strength, nominal strain at break, light transmittance and haze of the agricultural films in Examples 1 to 2 and Comparative Example 1 were tested respectively. The specific test results are shown in Table 1 below:

[0055] Table 1 Mechanical properties, light transmittance and haze test results of agricultural films

[0056]

[0057] It can be seen from Table 1 that, compared with Comparative Example 1, Examples 1 to 2 introduce UVA absorbers and UVB absorbers into the middle layer, which can, on the one hand, adjust the UVA and UVB light intensities of the light-transmitting agricultural film, and on the other hand, can also improve the tensile strength and nominal strain at break of the agricultural film, so that the agricultural film has better mechanical properties.

[0058] The agricultural films in Examples 1 to 2 and Comparative Example 1 were used to build greenhouses, and then the thermal insulation performance of the agricultural films was tested. The specific testing method was as follows: the temperature in the greenhouse was tested in the morning (5am), noon (13pm) and evening (12pm). The specific test results are shown in Table 2 below.

[0059] Table 2 Test results of thermal insulation performance of agricultural films

[0060]

[0061]

[0062] It can be seen from Table 2 that the temperature difference of the agricultural films in Examples 1 to 2 during use is 8.3°C and 8.1°C respectively, while the temperature difference of the agricultural film in Comparative Example 1 during use is 12.6°C. Therefore, the agricultural film in the present invention has a better heat preservation effect when used, and the temperature difference of the day is relatively small, which is conducive to growing crops.

[0063] When the agricultural films in Examples 1 to 2 and Comparative Example 1 are used, a total light intensity of 2200 μmol·m -2 ·s -1 The agricultural film was irradiated with simulated sunlight, and then the UVA light intensity and UVB light intensity passing through the agricultural film were tested respectively. The specific test results are shown in Table 3 below.

[0064] Table 3 Test results of UV light regulation performance of agricultural films

[0065]

[0066] As shown in Table 3, the agricultural films of Examples 1 to 2 can adjust the UVA light intensity and UVB light intensity passing through the agricultural films by setting the ultraviolet absorption layer, so that the ultraviolet light passing through the agricultural films can be beneficial to the growth and development needs of crops, and avoid the adverse effects of excessive ultraviolet light on crops. Therefore, the agricultural film of the present invention can absorb a certain amount of ultraviolet light, regulate the ratio of UVA and UVB entering the greenhouse, promote the growth of plants and the ability to resist external factors (such as anti-oxidation, etc.) through ultraviolet light, and use ultraviolet light to promote plant growth as much as possible.

[0067] Greenhouses were built using the agricultural films in Examples 1 to 2 and Comparative Example 1, and then crops were planted in the greenhouses. The anthocyanin and quercetin contents in the fruits of the crops were tested 20, 40 and 60 days after the crops bore fruit, and the anthocyanin content per 100 g of fruit was calculated. The specific test results are shown in Table 4 below; and the quercetin content per 100 g of fruit was calculated, as shown in Table 5.

[0068] Table 4 Test results of anthocyanin content at different times when agricultural films were used to grow crops

[0069]

[0070] Table 5 Test results of quercetin content at different times when agricultural films were used to grow crops

[0071]

[0072] As shown in Table 4 and Table 5, compared with Comparative Example 1, Examples 1 to 2 introduce UVA absorbers and UVB absorbers, and by adjusting the dosage ratio of the two, the intensity of ultraviolet light passing through the agricultural film is adjusted, so that the intensity of ultraviolet light passing through can promote the synthesis of certain nutrients in crops, such as anthocyanins, quercetin, etc. Compared with Example 2, the UVA in Example 1 accounts for a larger proportion, which is more conducive to the synthesis of anthocyanins, but too strong UVA is not conducive to the synthesis of anthocyanins, for example: the ultraviolet light intensity in Comparative Example 1 is too strong, which is not conducive to the growth of crops and the synthesis of nutrients. Compared with Example 1, the UVB content of Example 2 is higher, and its flavonol content increases under enhanced UVB radiation. Quercetin is a kind of flavonol, thereby promoting the synthesis of quercetin, while too strong UVB radiation is not conducive to the synthesis of quercetin, such as Comparative Example 1.

[0073] In summary, the agricultural film of the present invention uses a combination of ultraviolet absorbers (UVA and UVB) of different proportions to adjust the composition of ultraviolet rays in the greenhouse, so that the intensity of UVA and UVB passing through the agricultural film meets the growth needs of crops, and promotes the synthesis of nutrients in the fruits of crops, such as anthocyanins and quercetin. The agricultural film of the present invention has excellent light conversion ability, which absorbs the ultraviolet light in the sun, but retains a certain amount of ultraviolet rays, promoting the formation of plant morphology (such as leaf morphology, stem elongation, etc.) and bud germination, flower bud differentiation and flowering process.

[0074] The above is a detailed description of the embodiments of the present invention, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. A film, characterized in that: It comprises a heat-insulating layer, an ultraviolet absorbing layer and a heat-preserving layer which are stacked in sequence; the ultraviolet absorbing layer comprises the following components in mass percentage: 0.1-1% of UVA ultraviolet absorber, 0.5-5% of UVB ultraviolet absorber, Resin matrix 94-99.4%; The heat insulation layer contains a resin matrix and a heat insulation material; the mass of the heat insulation material is 0.5 to 20% of the total mass of the heat insulation layer; The thermal insulation layer contains a resin matrix and thermal insulation materials; The mass of the thermal insulation material is 0.5 to 20% of the total mass of the thermal insulation layer; The thermal insulation material is selected from at least one of tin oxide and zirconium oxide; The thermal insulation material is selected from aluminum silicate; The UVA ultraviolet absorber is selected from at least one of carbon quantum dots and nano zinc oxide; The UVB absorber is selected from at least one of 2,4-dihydroxybenzophenone and 2-hydroxy-4-n-octyloxybenzophenone.

2. The film according to claim 1, characterized in that: The resin matrix is ​​selected from at least one of polyethylene, nylon, polyvinyl alcohol, polypropylene, EPDM rubber, CTC resin and maleic anhydride.

3. The film according to claim 1, characterized in that: The thickness of the thermal insulation layer is 5 to 200 μm; and / or, the thickness of the ultraviolet absorption layer is 1 to 150 μm, And / or, the thickness of the thermal insulation layer is 1 to 180 μm; And / or, at least one of the heat insulating layer, the thermal insulation layer and the ultraviolet absorption layer further contains an auxiliary agent; the auxiliary agent is selected from at least one of a lubricant, a light stabilizer, an antioxidant, a solubilizer and a coupling agent.

4. The method for preparing a thin film according to any one of claims 1 to 3, characterized in that: The following steps are involved: The raw materials of the heat insulating layer, the ultraviolet absorption layer and the thermal insulation layer are mixed respectively, and then extruded by using a three-layer co-extrusion device to obtain the film.

5. Use of the film according to any one of claims 1 to 3 in the field of plant cultivation.

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