Light-sensitive master batch with adjustable illumination intensity and preparation method and application thereof

Abstract

The invention belongs to the technical field of agricultural films, and particularly relates to an illumination-intensity-adjustable photosensitive master batch and a preparation method and application thereof. The photosensitive master batch capable of adjusting the illumination intensity is prepared from the following raw materials in parts by weight: 80 to 90 parts of polyethylene; 10 to 20 parts of a photosensitive auxiliary agent; 2 to 5 parts of an antioxidant; 0.5-1 part of a dispersant; and 0.5-1 part of a lubricant. According to the photosensitive master batch capable of adjusting the illumination intensity, the light transmittance can be dynamically adjusted according to the illumination intensity, light shading with strong light and light transmitting with weak light are achieved, the invention further provides a preparation method of the photosensitive master batch, the photosensitive master batch is applied to preparation of a PO film, and the light utilization rate is increased.

Description

Technical Field

[0001] This invention belongs to the technical field of agricultural films, specifically relating to adjustable light intensity photosensitive masterbatch, its preparation method, and its application. Background Technology

[0002] Polyolefin (PO) agricultural films are widely used in modern facility agriculture due to their excellent low haze, high transparency, and superior comprehensive properties (such as weather resistance and mechanical strength). These films are typically made from high-grade olefin raw materials and functional additives, and are produced through processes such as external spraying and drying, providing good lighting conditions for crop growth.

[0003] However, traditional PO agricultural films have significant limitations in regulating light intensity. Their light transmittance is essentially fixed, unable to dynamically respond to changes in external light conditions. Under continuous strong light, excessively high transmittance can lead to a sharp increase in greenhouse temperature and excessive light intensity, easily causing crop scorching, excessive water transpiration, and photoinhibition. Conversely, under weak light conditions (such as cloudy or rainy days, or winter), the fixed transmittance cannot effectively increase the amount of light entering the greenhouse, potentially limiting the photosynthetic efficiency of crops and affecting their normal growth and development. Therefore, endowing agricultural films with "intelligent" light-sensing capabilities, enabling them to automatically reduce transmittance to minimize photothermal stress under strong light and maintain or increase transmittance to maximize light energy utilization under weak light, has become a key technological requirement for improving the environmental control capabilities of facility agriculture and promoting high-yield and high-quality crops.

[0004] Although theoretically, the light response regulation function can be achieved by adding photosensitive materials to PO film, developing a photosensitive masterbatch system that is efficient, stable, compatible with polyolefin substrates, and can accurately achieve the above-mentioned bidirectional regulation function of "strong light blocking and weak light transmission", and ensuring its reliability and durability in agricultural film processing and application, still faces many technical challenges.

[0005] Patent CN1242390A discloses a photodegradable and biodegradable polyethylene masterbatch. Its core lies in adding modified starch, photosensitizers (such as iron oxide and acetylated ferric acetone), degradation control agents (such as benzophenone and phenolic antioxidants), and high-mesh talc, along with a coupling agent to improve dispersibility. The aim is to accelerate the decomposition of plastic products (such as packaging films and agricultural films) under light and microbial action after disposal, thus solving environmental pollution problems. The photosensitizer's role is to initiate the photodegradation reaction, rather than to adjust the light transmittance during use.

[0006] Patent CN112795072A discloses a natural light-microbial dual-degradation masterbatch, whose components include polyethylene (micronized and granular grade), Fischer-Tropsch wax, photosensitive catalysts (such as lanthanide rare earth complexes, lanthanum / manganese stearate), calcium stearate, antioxidants, silane coupling agents, and may also include titanium dioxide, accelerators, and microbial culture media (cellulose, chitin, chitosan). The core mechanism of this technology is the activation of various active metal ions (copper, titanium, lanthanum, manganese, etc.) after plastic breakage and exposure to ultraviolet light or heat, triggering auto-oxidative degradation, while microorganisms attach and decompose the fragments. The photosensitive catalyst also aims to accelerate the final degradation of the material in its waste state.

[0007] While the aforementioned technologies are valuable in addressing plastic waste pollution, none of them address the core need of dynamically adjusting the light transmittance of agricultural films based on real-time ambient light intensity during their service life. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a photosensitive masterbatch with adjustable light intensity, which can dynamically adjust the light transmittance according to the light intensity and achieve "strong light blocking and weak light transmission". The present invention also provides its preparation method and applies it to the preparation of PO film to improve the utilization rate of light.

[0009] The adjustable light intensity photosensitive masterbatch of the present invention is composed of the following raw materials in parts by weight: Polyethylene: 80-90 parts; Photosensitizing agent: 10-20 parts; Antioxidant: 2-5 parts; Dispersant: 0.5~1 part; Lubricant: 0.5~1 part.

[0010] The polyethylene is obtained by mixing LDPE (low-density polyethylene) and MLLDPE (metallocene linear low-density polyethylene) at a mass ratio of (30-50):1. This specific ratio and type of polyethylene mixture serves as a carrier, ensuring that the masterbatch has good processing fluidity and excellent compatibility with PO matrix resin.

[0011] The photosensitizer is a mixture of silver chloride (AgCl) and copper oxide (CuO), wherein the mass ratio of silver chloride to copper oxide is 50:1 to 45:1. This specific ratio of photosensitizer is the core of achieving intelligent light regulation. Under visible light, especially strong light, silver chloride undergoes a photochemical reduction reaction to generate silver atoms, thus darkening and reducing light transmittance. However, when the light intensity decreases, the presence of copper oxide promotes the re-oxidation reaction of silver atoms with trace amounts of oxygen / chlorine in the environment, causing the color to fade and restoring high light transmittance, thereby achieving a reversible light regulation cycle.

[0012] The antioxidant is one or more of antioxidant 944, antioxidant 1010, and antioxidant 168, to provide a synergistic stabilizing effect and prevent thermo-oxidative aging of the masterbatch and final agricultural film during processing and use.

[0013] The dispersant is one of polyethylene wax, EVA wax, or ultra-high dispersant TAS-2A. These dispersants can effectively promote the uniform dispersion of solid particles such as photosensitizing agents in the polyethylene carrier, prevent agglomeration, and ensure the uniformity and stability of functions.

[0014] The lubricant is PPA (polymer processing aid), whose main function is to improve the melt flowability of the masterbatch during processing, reduce melt fracture, and improve the production efficiency and quality of extrusion granulation and subsequent blown film.

[0015] The preparation method of the adjustable light intensity photosensitive masterbatch of the present invention adopts a twin-screw extrusion process. The specific steps are as follows: according to the above production formula, the raw materials are precisely metered, high-speed mixed, and automatically conveyed to a co-rotating parallel twin-screw extruder. After melt plasticizing, extrusion, water cooling, pelletizing, weighing, and packaging, the final product of the adjustable light intensity photosensitive masterbatch is obtained. Preferred process parameters are: the temperature of zones one to ten of the twin-screw extruder is controlled at 150~180℃, the die head pressure is 3~5MPa, and the main extruder speed is 200~400rpm.

[0016] The application of the adjustable light intensity photosensitive masterbatch described in this invention is as follows: it is added to the raw materials of PO film in a specific ratio to prepare intelligent light-regulating PO agricultural film. The specific PO film formulation (by mass percentage) is as follows: MLLDPE (metallocene polyethylene): 10-15%; LDPE (high-pressure polyethylene): 10-15%; LLDPE (linear low-density polyethylene): 60-70%; The adjustable light intensity photosensitive masterbatch as described above: 3-5%; Thermal insulation agent (hydrotalcite): 2-3%; Anti-fogging and anti-dripping agent: 1-2%; Double-protection masterbatch (anti-aging, anti-UV): 2-3%.

[0017] After the above raw materials are mixed evenly, PO agricultural film with intelligent light-regulating function can be produced by conventional blow molding process.

[0018] Compared with the prior art, the beneficial effects of the present invention are: (1) The photosensitive masterbatch of the present invention, through the selection of a silver chloride / copper oxide composite photosensitive additive system and its specific ratio, successfully endows PO agricultural film with the ability to intelligently respond to changes in external light intensity. Under strong light conditions, it can automatically reduce light transmittance to avoid light and heat stress on crops in the greenhouse; under weak light conditions, it can maintain or restore high light transmittance to maximize light energy utilization, effectively solving the drawback of fixed light transmittance of traditional agricultural films and improving the environmental control level of facility agriculture. (2) The masterbatch formulation of this invention is scientifically designed, and the components have good synergistic effects. The specific LDPE / MLLDPE carrier system ensures good compatibility and processability with the matrix resin; the efficient dispersant ensures uniform dispersion of the photosensitive components and avoids functional failure points; the selection of antioxidants and lubricants ensures the stability and reliability of the masterbatch during production and application. The entire system is designed specifically for the long life cycle of agricultural films, and its function is long-lasting and stable.

[0019] (3) The preparation process of the present invention is mature and simple, and it is easy to realize large-scale industrial production. When applied, only a small amount of this masterbatch needs to be added to the existing PO film formula. There is no need to change the existing blown film process and equipment to produce high-performance intelligent light-switching agricultural film. It is convenient to implement, cost controllable, and has significant market promotion advantages. Detailed Implementation

[0020] The present invention will be further described below with reference to specific embodiments.

[0021] The following examples and comparative examples all use commercially available products.

[0022] The MLLDPE metallocene used below is grade 1018 and is commercially available from ExxonMobil Corporation in the United States.

[0023] LDPE (low-density polyethylene), grade 2420D, is commercially available from CNOOC Shell Petrochemicals Co., Ltd.

[0024] LLDPE polyethylene, graded 2230 and 2310, is commercially available from Bolu Chemical.

[0025] Silver chloride and copper oxide are commercially available from Tianjin Tiantuo Technology Development Co., Ltd. The lubricant is PPA, and the commercially available manufacturer is Shanghai Luju Polymer Co., Ltd. Thermal insulation agent: 36wt% hydrotalcite, commercially available from Jiahe Chaoyang Technology Co., Ltd.

[0026] Anti-fogging and anti-dripping agent: Model 3-7, commercially available from Hangzhou Yongsheng Plastic Antistatic Materials Factory.

[0027] Double-protection masterbatch: Model UV531, commercially available from Beijing Tiangang Additives Co., Ltd.

[0028] Dispersant: Model TAS-2A, commercially available from Suzhou Xingtai Optoelectronic Chemical Additives Co., Ltd.

[0029] Example 1 The adjustable light intensity photosensitive masterbatch is prepared according to the following raw material weight parts: Polyethylene (in which the mass ratio of LDPE to MLLDPE is 50:1): 80 parts; Photosensitizing agent (in which the mass ratio of silver chloride to copper oxide is 50:1): 10 parts; Antioxidant 1010: 2 parts; Dispersant: Polyethylene wax: 0.5 parts; Lubricant PPA: 0.5 parts; Preparation method: The above raw materials are precisely metered, mixed at high speed, and then automatically fed into a co-rotating parallel twin-screw extruder. Process parameters are controlled as follows: zone 1 to zone 10 temperature 150~165℃, die head pressure 3~4MPa, and main extruder speed 200~300rpm. After melt plasticizing, extrusion, water cooling, and pelletizing, the adjustable light intensity photosensitive masterbatch is obtained.

[0030] The above-mentioned adjustable light intensity photosensitive masterbatch is added to the raw materials of PO film to prepare PO film: MLLDPE: 15%; LDPE: 13%; LLDPE: 64%; Photosensitive masterbatch prepared in Example 1: 3%; Thermal insulation agent: 2%; Anti-fogging and anti-dripping agent: 1%; Double-protection masterbatch: 2%; Preparation method: After the above raw materials are mixed evenly, the intelligent light-regulating PO agricultural film is obtained by conventional blow molding process.

[0031] Example 2 The adjustable light intensity photosensitive masterbatch is prepared according to the following raw material weight parts: Polyethylene (in which the mass ratio of LDPE to MLLDPE is 30:1): 90 parts; Photosensitizing agent (in which the mass ratio of silver chloride to copper oxide is 45:1): 20 parts; Antioxidant 168: 5 parts; Dispersant EVA wax: 1 part; Lubricant PPA: 1 part; Preparation method: The above raw materials are precisely metered, mixed at high speed, and then automatically fed into a co-rotating parallel twin-screw extruder. Process parameters are controlled as follows: zone 1 to zone 10 temperature 165~180℃, die head pressure 4~5MPa, and main extruder speed 300~400rpm. After melt plasticizing, extrusion, water cooling, and pelletizing, the finished product is a photosensitive masterbatch with adjustable light intensity.

[0032] The above-mentioned adjustable light intensity photosensitive masterbatch is added to the raw materials of PO film to prepare PO film: MLLDPE: 10%; LDPE: 15%; LLDPE: 62%; Photosensitive masterbatch prepared in Example 2: 5%; Thermal insulation agent: 3%; Anti-fogging and anti-dripping agent: 2%; Double-protection masterbatch: 3%; Preparation method: After the above raw materials are mixed evenly, the intelligent light-regulating PO agricultural film is obtained by conventional blow molding process.

[0033] Example 3 The adjustable light intensity photosensitive masterbatch is prepared according to the following raw material weight parts: Polyethylene (in which the mass ratio of LDPE to MLLDPE is 40:1): 85 parts; Photosensitizing agent (in which the mass ratio of silver chloride to copper oxide is 47.5:1): 15 parts; Antioxidant 944: 3.5 parts; Dispersant TAS-2A: 0.8 parts; Lubricant PPA: 0.8 parts; Preparation method: The above raw materials are precisely metered, mixed at high speed, and then automatically fed into a co-rotating parallel twin-screw extruder. Process parameters are controlled as follows: zone 1 to zone 10 temperature 155~175℃, die head pressure 3.5~4.5MPa, and main extruder speed 250~350rpm. After melt plasticizing, extrusion, water cooling, and pelletizing, the adjustable light intensity photosensitive masterbatch is obtained.

[0034] The above-mentioned adjustable light intensity photosensitive masterbatch is added to the raw materials of PO film to prepare PO film: MLLDPE: 12%; LDPE: 12%; LLDPE: 65%; Photosensitive masterbatch prepared in Example 3: 4.5%; Thermal insulation agent: 2.5%; Anti-fogging and anti-dripping agent: 1.5%; Double-protection masterbatch: 2.5%; Preparation method: After the above raw materials are mixed evenly, the intelligent light-regulating PO agricultural film is obtained by conventional blow molding process.

[0035] Example 4 The adjustable light intensity photosensitive masterbatch is prepared according to the following raw material weight parts: Polyethylene (in which the mass ratio of LDPE to MLLDPE is 30:1): 80 parts; Photosensitizing agent (in which the mass ratio of silver chloride to copper oxide is 45:1): 10 parts; Antioxidant 1010: 1 part; Antioxidant 168: 1 part; Dispersant: Polyethylene wax: 0.5 parts; Lubricant PPA: 1 part; The preparation method is the same as in Example 1, but this formulation has a higher proportion of MLLDPE.

[0036] The above-mentioned adjustable light intensity photosensitive masterbatch was added to the raw materials of PO film to prepare PO film, and the steps and contents were the same as in Example 1.

[0037] Example 5 The adjustable light intensity photosensitive masterbatch is prepared according to the following raw material weight parts: Polyethylene (in which the mass ratio of LDPE to MLLDPE is 50:1): 90 parts; Photosensitizing agent (in which the mass ratio of silver chloride to copper oxide is 50:1): 20 parts; Antioxidant 944: 5 parts; Dispersant EVA wax: 1 part; Lubricant PPA: 0.5 parts; The preparation method is the same as in Example 2.

[0038] The above-mentioned adjustable light intensity photosensitive masterbatch was added to the raw materials of PO film to prepare PO film, and the steps and contents were the same as in Example 2.

[0039] Example 6 The adjustable light intensity photosensitive masterbatch is prepared according to the following raw material weight parts: Polyethylene (in which the mass ratio of LDPE to MLLDPE is 35:1): 85 parts; Photosensitizing agent (in which the mass ratio of silver chloride to copper oxide is 48:1): 18 parts; Antioxidant 168: 4 parts; Dispersant TAS-2A: 0.6 parts; Lubricant PPA: 0.7 parts; Its preparation method is the same as that in Example 3.

[0040] The above-mentioned adjustable light intensity photosensitive masterbatch is added to the raw materials of PO film to prepare PO film: MLLDPE: 14%; LDPE: 11.2%; LLDPE: 63%; Photosensitive masterbatch prepared in Example 6: 4.5%; Thermal insulation agent: 2.8%; Anti-fogging and anti-dripping agent: 1.7%; Double-protection masterbatch: 2.8%; Preparation method: After the above raw materials are mixed evenly, the intelligent light-regulating PO agricultural film is obtained by conventional blow molding process.

[0041] Comparative Example 1 This comparative example is the same as Example 1, but the photosensitizing agent (where the mass ratio of silver chloride to copper oxide is 50:1) is removed from the photosensitizing masterbatch: 10 parts.

[0042] Comparative Example 2 This comparative example is the same as Example 1, but the photosensitizing agent in the photosensitizing masterbatch is only silver chloride: 10 parts.

[0043] Comparative Example 3 This comparative example is the same as Example 1, but the photosensitizing agent in the photosensitizing masterbatch is only copper oxide: 10 parts.

[0044] The appearance, melt flow rate at 190℃, and moisture content of the adjustable light intensity photosensitive masterbatch in the above embodiments and comparative examples are shown in Table 1. The thickness of the prepared PO film, tensile strength, nominal strain at break, right-angle tear strength, haze, and dripping properties were measured according to Q / ZBKL002-2024 using a standard thickness gauge. Light intensity A: Using a PG200N handheld spectrometer, the light intensity of 1 acre of land in both the embodiments and comparative examples was covered with a shed. The light intensity A was measured using the PG200N handheld spectrometer, and the light intensity was 82,000 Lux. The light intensity after covering with the PO film was measured and recorded as light intensity A (the average value after three parallel measurements, with the deviation of the three measurements within ±5%). Light intensity B: Using a PG200N handheld spectrophotometer, the 1-acre plots of both the example and comparative examples were covered with a shed. The light intensity B was measured using the PG200N handheld spectrophotometer, and the light intensity was 121,000 Lux. The light intensity after covering with PO film was measured and recorded as light intensity B (the average value after three parallel measurements, with the deviation of the three measurements within ±5%).

[0045] The test results are shown in Table 2.

[0046] Table 1 Test Results

[0047] Table 2 Detection Results

Claims

1. A photosensitive masterbatch with adjustable light intensity, characterized in that: It consists of the following raw materials in parts by weight: Polyethylene: 80-90 parts; Photosensitizing agent: 10-20 parts; Antioxidant: 2-5 parts; Dispersant: 0.5~1 part; Lubricant: 0.5~1 part.

2. The adjustable light intensity photosensitive masterbatch according to claim 1, characterized in that: The polyethylene is obtained by mixing LDPE and MLLDPE in a mass ratio of 30~50:

1.

3. The adjustable light intensity photosensitive masterbatch according to claim 2, characterized in that: The photosensitizer is a mixture of silver chloride and copper oxide, with a mass ratio of silver chloride to copper oxide of 50:1 to 45:

1.

4. The adjustable light intensity photosensitive masterbatch according to claim 1, characterized in that: The antioxidant is one or more of 944, 1010, and 168.

5. The adjustable light intensity photosensitive masterbatch according to claim 1, characterized in that: The dispersants are polyethylene wax, EVA wax, and ultra-high dispersant TAS-2A.

6. The adjustable light intensity photosensitive masterbatch according to claim 1, characterized in that: The lubricant is PPA.

7. A method for preparing an adjustable light intensity photosensitive masterbatch according to any one of claims 1-6, characterized in that: The raw material is extruded and pelletized using a twin-screw extrusion process to obtain a photosensitive masterbatch with adjustable light intensity.

8. The method for preparing the adjustable light intensity photosensitive masterbatch according to claim 7, characterized in that: The more specific process is as follows: according to the production formula, the product is metered, mixed, conveyed, plasticized by a twin-screw extruder, extruded, pelletized, weighed, packaged, and stored.

9. The application of the adjustable light intensity photosensitive masterbatch according to any one of claims 1-6, characterized in that: PO membranes are prepared by adding a photosensitive masterbatch with adjustable light intensity to the raw materials of PO membranes.

10. The application of the adjustable light intensity photosensitive masterbatch according to claim 9, characterized in that: PO film is blow-molded according to the following mass percentages: MLLDPE, 10-15%; LDPE, 10-15%; LLDPE, 60-70%; adjustable light intensity photosensitive masterbatch, 3-5%; heat preservation agent, 2-3%; anti-fogging and anti-dripping agent, 1-2%; double anti-fogging masterbatch, 2-3%.

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