A rice seedling raising special cooling light conversion greenhouse film based on a PE base material and a preparation method thereof

Abstract

The application provides a PE substrate-based rice seedling raising special cooling light conversion greenhouse film and a preparation method thereof, and belongs to the technical field of PE films. The cooling light conversion greenhouse film comprises an outer layer, a middle layer and an inner layer which are stacked in sequence. The preparation raw materials of the outer layer comprise PE resin, cesium tungsten bronze, the preparation raw materials of the middle layer comprise PE resin, antimony tin oxide and rare earth inorganic compound light conversion agent, and the preparation raw materials of the inner layer comprise PE resin, heat preservation agent and flow drop anti-fog agent. The cooling light conversion greenhouse film uses PE resin as the base resin, and the cesium tungsten bronze of the outer layer, the antimony tin oxide and the rare earth inorganic compound light conversion agent of the middle layer and the moisture retention agent and the flow drop anti-fog agent of the inner layer are complementary to each other, so that the cooling effect is improved and the adaptability in the southern late rice seedling raising process is improved at low cost.

Description

Technical Field

[0001] This invention belongs to the field of PE film technology, and in particular relates to a cooling and light conversion greenhouse film for rice seedling raising based on PE substrate and its preparation method. Background Technology

[0002] Rice seedling raising is a core step in rice cultivation, and the quality of the seedlings directly determines the survival rate and final yield after transplanting. Currently, the plastic film used in rice seedling raising greenhouses commonly suffers from the following technical defects, severely impacting seedling quality:

[0003] Ordinary PE greenhouse film has a single function: The conventional rice seedling film on the market is based on PE and only has basic heat preservation and light transmission functions. It does not have heat insulation and cooling functions. In the late rice seedling season in June and July in the south, the temperature inside the greenhouse can easily soar to above 45℃, which directly causes problems such as high temperature scorching of seedlings, excessive growth and thinness, rotting and death of seedlings, and a significant reduction in the germination rate.

[0004] Existing functional films have poor adaptability: some light-converting agricultural films can only achieve spectral conversion and cultivate strong seedlings, but have no cooling effect. In high-temperature environments, they not only cannot play a role in strengthening seedlings, but also aggravate heat accumulation in the greenhouse and increase the risk of burning seedlings; conventional cooling films mostly use non-PE substrates or add shading coatings, resulting in insufficient light transmittance, insufficient light for seedlings, weak root systems, and cannot accurately match the light requirements of rice seedling cultivation.

[0005] High production and promotion costs: Non-PE substrate functional agricultural films have complex production processes, require specialized equipment, cannot be adapted to existing PE blown film production lines, are difficult to scale up, have high costs, and are difficult to promote on a large scale.

[0006] No specialized design for rice seedling raising: Existing functional agricultural films have not been specifically developed to meet the temperature and light requirements for rice seedling growth, and their temperature control and spectral conversion are not targeted.

[0007] Therefore, how to provide a special cooling and light conversion greenhouse film for rice seedling raising based on PE substrate to solve the problems of high temperature burning of seedlings, weak seedlings, and poor compatibility with existing production equipment in existing rice seedling greenhouse films is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0008] To address the shortcomings of the existing technology, this invention aims to provide a cooling light conversion greenhouse film for rice seedling cultivation based on PE substrate and its preparation method. The three-layer structure of this cooling light conversion greenhouse film uses PE resin as the matrix resin. Cesium tungsten bronze with a wider absorption wavelength range is added to the outer layer. Tin antimony oxide with a relatively narrow absorption wavelength range and rare earth inorganic compound light-converting agent that can convert ultraviolet light into visible light required for rice photosynthesis are added to the middle layer. A humectant and anti-drip and anti-fogging agent are added to the inner layer. The three layers work synergistically and complementarily to improve the cooling effect at low cost and enhance the adaptability of the cooling light conversion greenhouse film in the late rice seedling cultivation process in southern China.

[0009] The first objective of this invention is to provide a special cooling and light conversion greenhouse film for rice seedling raising based on PE substrate, which includes an outer layer, a middle layer and an inner layer stacked in sequence;

[0010] The raw materials for preparing the outer layer include PE resin and cesium tungsten bronze;

[0011] The raw materials for preparing the middle layer include PE resin, tin antimony oxide, and rare earth inorganic compound light conversion agent;

[0012] The raw materials for preparing the inner layer include PE resin, heat preservation agent, and anti-drip and anti-fogging agent.

[0013] Preferably, the PE resin is selected from at least one of LDPE and LLDPE.

[0014] More preferably, the melt index of the PE resin is 0.2~2g / 10min under the conditions of 190℃ and 2.16kg load.

[0015] More preferably, the PE resin in the outer layer and the middle layer is selected from LLDPE resin, and the PE resin in the inner layer is selected from LDPE resin.

[0016] Preferably, the average particle size of the cesium tungsten bronze is 20-80 nm. In this invention, the molecular formula of the cesium tungsten bronze is Cs. 0.33 WO3 has a regular hexahedral structure. More preferably, the average particle size of the cesium tungsten bronze is 20~60nm, for example, 30nm, 40nm, or 50nm.

[0017] Preferably, the average particle size of the antimony tin oxide is 40~100nm, more preferably 40~80nm, for example, 50nm, 60nm, or 70nm.

[0018] Preferably, the rare earth inorganic compound light-converting agent is MS:Eu,Re, wherein M is selected from at least one of Mg, Ca, Sr, and Ba, and Re is selected from at least one of Ce, Dy, Sm, Yb, Tb, Tm, Pr, Nd, Sm, Gd, Er, and Cu. More preferably, the rare earth inorganic compound light-converting agent is a combination of a red light-converting agent (e.g., CaS:Eu,Sm) and a blue light-converting agent (e.g., CaS:Eu,Cu), for example, the rare earth inorganic compound light-converting agent is the red light-converting agent and the blue light-converting agent in a mass ratio of 1:1 to 2.5.

[0019] Preferably, by weight, the raw materials for preparing the outer layer include 100 parts of PE resin and 1-3 parts of cesium tungsten bronze; the raw materials for preparing the middle layer include 100 parts of PE resin, 0.5-2 parts of tin antimony oxide, and 0.1-1 parts of rare earth inorganic compound light-converting agent. Preferably, in this invention, by adding a larger amount of cesium tungsten bronze to the outer layer and a smaller amount of tin oxide antimony and rare earth inorganic compound light-converting agents to the middle layer, the following advantages are achieved: First, these inorganic compounds are distributed in different layers, which, compared to being uniformly distributed in one layer, facilitates more uniform dispersion and allows them to fully exert their function. Second, the larger amount of cesium tungsten bronze in the outer layer can effectively block most of the near-infrared light, while the smaller amount of tin oxide antimony in the middle layer can act as a "bottom-line" component to block near-infrared light passing through the outer layer. Third, placing the smaller amount of rare earth inorganic compound light-converting agents in the middle layer avoids uneven dispersion, encapsulation, or shielding due to a large overall amount of inorganic compounds, thus preventing them from effectively and stably exerting their light conversion function. More preferably, the mass fraction of cesium tungsten bronze is greater than the sum of the mass fractions of the tin oxide antimony and rare earth inorganic compound light-converting agents, or the mass fraction of cesium tungsten bronze is greater than the mass fraction of the tin oxide antimony or the mass fraction of the rare earth inorganic compound light-converting agents.

[0020] Preferably, the raw materials for preparing the inner layer, by weight, include 100 parts of PE resin, 2-5 parts of thermal insulation agent, and 0.5-2.0 parts of anti-drip and anti-fogging agent. In this invention, the thermal insulation agent is selected from at least one of hydrotalcite, talc powder, kaolin, sericite, diatomaceous earth, calcium carbonate, and mica powder; the anti-drip and anti-fogging agent is selected from at least one of glyceryl monostearate, polyglycerol ester, sorbitan monostearate, sorbitan monooleate, polyoxyethylene sorbitan monooleate, fluorinated surfactant, and silicone surfactant.

[0021] Preferably, the raw materials for preparing the outer layer further include at least one of a light stabilizer, an antioxidant, and a lubricant, and the raw materials for preparing the middle layer further include a dispersant. In this invention, by adding a light stabilizer and an antioxidant to the outer layer, the overall light and oxygen aging resistance of the greenhouse film is improved; by adding a lubricant to the outer layer, its processing performance and anti-adhesion properties are improved; and by adding a dispersant to the middle layer, its uniformity is improved. Furthermore, the light stabilizer is selected from at least one of stabilizer 944, light stabilizer 622, light stabilizer 783, and light stabilizer 788; the antioxidant is selected from at least one of antioxidant 1010, antioxidant 1076, antioxidant CA, antioxidant 245, antioxidant 168, and antioxidant 626; the lubricant is selected from at least one of paraffin wax, polyethylene wax, stearic acid, calcium stearate, oleamide, and erucamide; and the dispersant is selected from at least one of paraffin wax and polyethylene wax. The amounts of the light stabilizer, the antioxidant, the lubricant, and the dispersant can be independently 0.05 to 2 parts each.

[0022] Preferably, the thickness of the cooling light conversion greenhouse film is 0.1~0.3mm.

[0023] Preferably, the thickness ratio of the outer layer, the middle layer and the inner layer is 0.8~1.2:0.8~1.2:0.2~0.5.

[0024] The second objective of this invention is to provide a method for preparing the aforementioned cooling light conversion greenhouse film, which includes the following steps:

[0025] S1. Mix the raw materials for the preparation of the outer layer, the raw materials for the preparation of the middle layer, and the raw materials for the preparation of the inner layer respectively, and extrude and granulate them to obtain the outer layer masterbatch, the middle layer masterbatch, and the inner layer masterbatch respectively.

[0026] S2. Add the outer layer masterbatch, middle layer masterbatch, and inner layer masterbatch to a three-layer co-extrusion PE blown film machine, blow mold, slit and roll up to obtain the cooling light conversion greenhouse film.

[0027] Preferably, the extrusion granulation temperature in S1 is 160-175°C.

[0028] Preferably, the blow molding temperature in S2 is 160-190°C, and the blow ratio is 2.5~3.5:1.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The cooling light conversion greenhouse film of the present invention uses PE resin as the only base material, abandoning other composite base materials. It can be directly produced using existing PE blown film production lines without the need for equipment modification. It is convenient for large-scale production, has low cost, is easily accepted by farmers, and is easy to promote and apply on a large scale.

[0031] 2. The cooling light conversion greenhouse film of the present invention achieves low cost by compounding cesium tungsten bronze, tin oxide antimony and rare earth inorganic compound light conversion agents in different layers to make each component fully exert its function. In the process of raising late rice seedlings in the south, it can achieve a temperature reduction of 8-10℃ compared with ordinary PE film, and the temperature inside the greenhouse is stabilized below 35℃, resulting in good seedling growth and solving the problem of high temperature burning of rice seedlings. Detailed Implementation

[0032] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0033] Unless otherwise specified, all raw materials used in this invention are commercially available, and the rare earth inorganic compound light-converting agent is obtained from Gansu Rare Earth New Materials Co., Ltd.

[0034] Example 1

[0035] This embodiment provides a special cooling and light conversion greenhouse film for rice seedling raising based on PE substrate, which includes an outer layer, a middle layer, and an inner layer stacked sequentially. As shown in Table 1 by weight, the outer layer is prepared from 100 parts of LLDPE with an MFI of 1.0 g / 10 min, 1 part of cesium tungsten bronze with an average particle size of 30 nm, 0.1 parts of light stabilizer 188, and 0.1 parts of antioxidant 1010. The middle layer is prepared from 100 parts of LLDPE with an MFI of 1.0 g / 10 min, 0.5 parts of antimony tin oxide with an average particle size of 50 nm, 0.2 parts of rare earth inorganic compound light-converting agent CaS:Eu,Sm, 0.2 parts of rare earth inorganic compound light-converting agent CaS:Eu,Cu, and 0.1 parts of polyethylene wax. The inner layer is prepared from 100 parts of LDPE with an MFI of 1.9 g / 10 min, 2 parts of talc, and 0.5 parts of glyceryl monostearate.

[0036] The preparation steps of the cooling light conversion greenhouse film include:

[0037] S1. The raw materials for preparing the outer layer, the raw materials for preparing the middle layer, and the raw materials for preparing the inner layer are mixed and extruded and granulated in a twin-screw extruder with a temperature range of 160~175℃ to obtain outer layer masterbatch, middle layer masterbatch and inner layer masterbatch respectively.

[0038] S2. Add the outer layer masterbatch, middle layer masterbatch, and inner layer masterbatch to a three-layer co-extrusion PE blown film machine. Under the condition of a temperature range of 160~190℃, control the blow-up ratio to 3:1, blow-mold and cut and roll up to obtain a cooling light conversion greenhouse film with outer, middle and inner layers stacked in sequence. The total thickness of the greenhouse film is 0.12mm, and the thickness ratio of the outer, middle and inner layers is 1:1:0.4.

[0039] Examples 2-4 and Comparative Examples 1-3

[0040] The above embodiments and comparative examples provide a special cooling and light conversion greenhouse film for rice seedling raising based on PE substrate. The only difference between it and Example 1 is that the raw materials for the preparation of the outer and middle layers are different from those in Example 1, as shown in Table 1. The rest is the same as in Example 1.

[0041] Table 1: Raw material composition for the preparation of cooling light conversion greenhouse films in Examples 1-4 and Comparative Examples 1-3

[0042]

[0043] Using commercially available ordinary PE greenhouse film as a reference example, the following performance tests were conducted on the greenhouse films of Examples 1-4, Comparative Examples 1-3, and the reference example:

[0044] 1. Mechanical properties: Referring to GB / T 1040.3-2006, the greenhouse film was cut into Type 2 strips with a width of 25mm, and its mechanical strength (longitudinal) was tested at a test rate of 500 mm / min. The unit is MPa. The results are shown in Table 2.

[0045] 2. Cooling and Seedling Strengthening Effects: The greenhouse film was used in the rice seedling cultivation process of late-season rice in southern China (Changsha, Hunan late-season rice seedling base). On the 14th day after sowing (sunny day), the highest temperature inside the film was recorded throughout the day, as well as the temperatures inside and outside the greenhouse at four time points: 11:00 AM, 12:00 PM, 1:00 PM, and 2:00 PM. The average temperature difference between inside and outside the greenhouse (temperature inside the greenhouse - temperature outside the greenhouse) was calculated to evaluate the cooling effect of the greenhouse film and ordinary PE film. The fresh weight of 20 seedlings was weighed to evaluate the seedling strengthening effect of the greenhouse film.

[0046] Table 2: Performance of Different Greenhouse Films

[0047]

[0048] As shown in Table 2, the greenhouse films of Examples 1-4 of the present invention have a good cooling effect. Compared with commercially available ordinary PE greenhouse films, they can reduce the temperature inside the greenhouse by 8-10℃, and have a significant effect on the seedling cultivation of late rice in the south.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that after reading this application specification, they can still modify or make equivalent substitutions to the specific implementation of the present invention, but these modifications or changes do not depart from the protection scope of the pending claims of the present invention.

Claims

1. A special cooling and light-conversion greenhouse film for rice seedling raising based on PE substrate, characterized in that, It includes an outer layer, a middle layer, and an inner layer that are stacked in sequence; The outer layer is prepared using PE resin and cesium tungsten bronze as raw materials. The raw materials for preparing the middle layer include PE resin, tin antimony oxide, and rare earth inorganic compound light conversion agent; The raw materials for preparing the inner layer include PE resin, heat insulation agent, and anti-drip and anti-fogging agent.

2. The cooling light conversion greenhouse film according to claim 1, characterized in that, The PE resin is selected from at least one of LDPE and LLDPE.

3. The cooling light conversion greenhouse film according to claim 1, characterized in that, The average particle size of the cesium tungsten bronze is 20~80 nm.

4. The cooling light conversion greenhouse film according to claim 1, characterized in that, The average particle size of the antimony tin oxide is 40~100nm.

5. The cooling light conversion greenhouse film according to claim 1, characterized in that, The rare earth inorganic compound light-converting agent is MS:Eu,Re, where M is selected from at least one of Mg, Ca, Sr, and Ba, and Re is selected from at least one of Ce, Dy, Sm, Yb, Tb, Tm, Pr, Nd, Gd, Er, and Cu.

6. The cooling light conversion greenhouse film according to claim 1, characterized in that, The outer layer is prepared by means of 100 parts of PE resin and 1-3 parts of cesium tungsten bronze by weight. And / or, the raw materials for preparing the middle layer include 100 parts of PE resin, 0.5 to 2 parts of antimony tin oxide, and 0.1 to 1 part of rare earth inorganic compound light-converting agent; And / or, the raw materials for preparing the inner layer include 100 parts of PE resin, 2-5 parts of heat-insulating agent and 0.5-2.0 parts of anti-drip and anti-fogging agent.

7. The cooling light conversion greenhouse film according to claim 1, characterized in that, The raw materials for preparing the outer layer also include at least one of light stabilizers, antioxidants, and lubricants; And / or, the raw materials for preparing the intermediate layer also include a dispersant.

8. The cooling light conversion greenhouse film according to claim 1, characterized in that, The thickness of the cooling light conversion greenhouse film is 0.1~0.3mm; And / or, the thickness ratio of the outer layer, the middle layer and the inner layer is 0.8~1.2:0.8~1.2:0.2~0.

5.

9. The method for preparing the cooling light conversion greenhouse film according to any one of claims 1 to 8, characterized in that, Includes the following steps: S1. Mix the raw materials for the preparation of the outer layer, the raw materials for the preparation of the middle layer, and the raw materials for the preparation of the inner layer respectively, and extrude and granulate them to obtain the outer layer masterbatch, the middle layer masterbatch, and the inner layer masterbatch respectively. S2. Add the outer layer masterbatch, middle layer masterbatch, and inner layer masterbatch to a three-layer co-extrusion PE blown film machine, blow mold, slit and roll up to obtain the cooling light conversion greenhouse film.

10. The method for preparing the cooling light conversion greenhouse film according to claim 9, characterized in that, The extrusion granulation temperature described in S1 is 160-175℃; And / or, the blow molding temperature described in S2 is 160-190℃ and the blow ratio is 2.5~3.5:1.

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