A spectroscopic greenhouse composite film and preparation method thereof

Abstract

The invention discloses a spectroscopic greenhouse composite film and a preparation method thereof, and relates to the technical field of composite films. The greenhouse composite film is composed of a surface layer, a middle layer, and an inner layer from top to bottom; wherein the surface layer includes the following raw materials, calculated in 100 parts by mass: 6 to 8 parts of antioxidant masterbatch, 2 to 3 parts of rheological agent masterbatch, 2 to 3 parts of splitter masterbatch, and the rest are matrix masterbatch; wherein the middle layer includes the following raw materials, calculated in 100 parts by mass: 6 to 8 parts of antioxidant masterbatch, 2 to 3 parts of rheological agent masterbatch, 2 to 3 parts of splitter masterbatch, 12 to 16 parts of antifog agent masterbatch, 18 to 24 parts of ethylene-vinyl acetate copolymer, and the rest are matrix masterbatch; wherein the inner layer includes the following raw materials, calculated in 100 parts by mass: 6 to 8 parts of antioxidant masterbatch, 2 to 3 parts of rheological agent masterbatch, 12 to 16 parts of antifog agent masterbatch, 18 to 24 parts of ethylene-vinyl acetate copolymer, and the rest are matrix masterbatch.

Description

Technical Field

[0001] The present invention relates to the technical field of composite films, in particular to a spectroscopic greenhouse composite film and a preparation method thereof. Background Art

[0002] With the advancement of agricultural modernization, greenhouse cultivation technology has been widely used. As an important component of cultivation, greenhouse composite film plays a key role in regulating the light environment within the greenhouse, directly affecting the photosynthetic efficiency and growth of crops. However, to promote plant growth, traditional greenhouse composite films contain photocatalytic agents to filter and absorb light that is not conducive to plant growth, thereby increasing yields. However, these films often have poor transparency and high haze, resulting in suboptimal light transmission. Furthermore, due to the high humidity in greenhouses, water vapor easily forms droplets on the film surface, which fall directly onto the crop surface. This not only affects crop growth, but also easily causes a decrease in light transmittance.

[0003] In summary, it is of great significance to solve the above problems and prepare a spectral greenhouse composite film. Summary of the Invention

[0004] The object of the present invention is to provide a spectroscopic greenhouse composite film and a preparation method thereof to solve the problems raised in the above background technology.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A spectroscopic greenhouse composite film, from top to bottom, comprises: a surface layer, a middle layer, and an inner layer;

[0007] The surface layer comprises the following raw materials, calculated based on 100 parts by mass: 6 to 8 parts of antioxidant masterbatch, 2 to 3 parts of rheological agent masterbatch, 2 to 3 parts of splitter masterbatch, and the rest is matrix masterbatch;

[0008] The intermediate layer comprises the following raw materials, calculated based on 100 parts by mass: 6 to 8 parts of antioxidant masterbatch, 2 to 3 parts of rheological agent masterbatch, 2 to 3 parts of splitter masterbatch, 12 to 16 parts of antifogging agent masterbatch, 18 to 24 parts of ethylene-vinyl acetate copolymer, and the rest is matrix masterbatch;

[0009] The inner layer comprises the following raw materials, calculated based on 100 parts by mass: 6 to 8 parts of antioxidant masterbatch, 2 to 3 parts of rheological agent masterbatch, 12 to 16 parts of antifogging agent masterbatch, 18 to 24 parts of ethylene-vinyl acetate copolymer, and the rest being matrix masterbatch.

[0010] Preferably, the antifog agent accounts for 50-60 wt % of the antifog agent masterbatch, and the rest is the base masterbatch; the mass ratio of the antifog agent masterbatch to the ethylene-vinyl acetate copolymer is 1:1.5-2.

[0011] Preferably, the preparation method of the anti-fogging agent comprises the following steps: (1) uniformly mixing glyceryl monostearate, 3-(isomethacryloyloxy)propyltrimethoxysilane, and triethylamine, stirring at 100-105° C. for 3-4 hours, filtering, washing with anhydrous ethanol, and drying to obtain modified glyceryl monostearate;

[0012] (2) Add tetraethyl orthosilicate to a 30% ethanol solution, adjust the pH to 6, and stir at 50-60°C for 1-1.5 hours to obtain a silica sol;

[0013] (3) Add nano-alumina to 30% ethanol solution and disperse it evenly by ultrasonication. Add modified monostearate glyceryl and cetyltrimethylammonium bromide, stir at 40-50°C for 1-1.5 hours, add 25-30 parts of silica sol, adjust the pH to 8, stir at 60-70°C for 6-8 hours, let it stand for 24-36 hours, filter, wash, and dry to obtain an anti-fog agent.

[0014] Preferably, the modified glyceryl monostearate comprises the following raw materials, calculated by mass: 5.5-6.5 parts of glyceryl monostearate, 3-4 parts of 3-(methacryloyloxy)propyltrimethoxysilane, and 0.04-0.05 parts of triethylamine;

[0015] The silica sol comprises the following raw materials, calculated by mass: 5-8 parts of tetraethyl orthosilicate, 18-20 parts of 30% ethanol solution;

[0016] The anti-fog agent comprises the following raw materials, calculated by mass: 1-3 parts of nano-alumina, 50-60 parts of 30% ethanol solution, 0.6-1 parts of modified monostearate, 0.4-0.6 parts of cetyltrimethylammonium bromide, and 25-30 parts of silica sol.

[0017] Preferably, the ethylene-vinyl acetate copolymer includes 30-40 wt % of a modified ethylene-vinyl acetate copolymer.

[0018] Preferably, the preparation method of the modified ethylene-vinyl acetate copolymer comprises the following steps: (1) uniformly mixing tetramethyldisilane, Karsedt catalyst, and allyl methacrylate, stirring at 70-80° C. for 2-3 hours, and purifying to obtain a modifier;

[0019] (2) Ethylene-vinyl acetate copolymer, diisopropylbenzene peroxide and modifier are premixed and then added into a twin-screw extruder for melting and stirring at 170-180°C and a rotation speed of 50-60 r / min for 10-15 minutes, extruded into granules, and purified to obtain modified ethylene-vinyl acetate copolymer.

[0020] Preferably, the modifier comprises the following raw materials, calculated by mass: 1.3-1.4 parts of tetramethyldisilane, 0.03-0.04 parts of Karsedt catalyst, and 2.5-2.6 parts of allyl methacrylate;

[0021] The modified ethylene-vinyl acetate copolymer comprises the following raw materials, calculated by mass: 38-40 parts of ethylene-vinyl acetate copolymer, 0.03-0.05 parts of dicumyl peroxide, and 2-3 parts of a modifier.

[0022] Preferably, the antioxidant masterbatch contains 6-7wt% of the antioxidant, and the rest is the matrix masterbatch; the rheological agent masterbatch contains 3-4wt% of the rheological agent, and the rest is the matrix masterbatch; the splitter masterbatch contains 12-15wt% of the splitter, and the rest is the matrix masterbatch;

[0023] The splitter includes a red-orange light additive, a fluorescent agent, a dispersant, a yellow pigment, and a red pigment in a mass ratio of 10:0.5:0.8:0.02:0.04;

[0024] The matrix masterbatch includes one or both of LLDPE and mLLDPE.

[0025] More preferably, the method for preparing the spectral greenhouse composite film comprises the following steps:

[0026] S1: According to the formula, each raw material and the base masterbatch are mixed in sequence, extruded and granulated to obtain the corresponding masterbatch;

[0027] S2: Blend the raw materials in sequence according to the formula of the surface layer, the middle layer and the inner layer, use a three-layer film blowing machine to co-extrude, plasticize into a film, and dry to obtain a spectroscopic greenhouse composite film.

[0028] More preferably, during the co-extrusion process, the extrusion temperature is 190-220°C; during the drying process, the drying temperature is 80-90°C; and the thickness of the spectroscopic greenhouse composite film is 80-100 μm.

[0029] Compared with the prior art, the beneficial effects achieved by the present invention are: by setting a surface layer, an intermediate layer, and an inner layer, and adding an anti-fog agent and a partially modified ethylene-vinyl acetate copolymer to the intermediate layer and the inner layer, the present application significantly improves the long-term anti-fog performance of the greenhouse composite film, while improving its light transmittance, thereby improving its light splitting effect.

[0030] Among them, the preparation method of the anti-fog agent is to use a hydroxyl group in monostearate and a silicon-oxygen bond in 3-(isobutyleneoxy)propyltrimethoxysilane to break and then graft to generate methanol, and obtain modified monostearate; further, the remaining siloxane in the modified monostearate is hydrolyzed in an ethanol aqueous solution to modify nano-alumina, and tetraethyl orthosilicate is used to prepare silica sol by a solution gel method, and the modified nano-alumina is coated to obtain the anti-fog agent.

[0031] Among them, glyceryl monostearate has excellent anti-fog properties, but it is easy to precipitate on the surface of the composite film during use. As the droplets are lost, the anti-fog failure is shortened and the transmittance and spectral performance decrease. By grafting a silane coupling agent and further loading it on the surface of nano-alumina, the migration rate of the anti-fog agent can be reduced and the anti-fog duration can be increased. Subsequently, a layer of silica is coated on the surface of the modified nano-alumina using silica sol. The porous structure can further extend the anti-fog duration and improve the sustained release effect. At the same time, it has a heterogeneous nucleation effect, which can refine the grains, reduce haze, and increase transmittance. At the same time, after being coated with silica, the surface of the nano-alumina is smoother and flatter, which can reduce the scattering and reflection of light on the surface of the composite film and improve the transmittance of light. It itself has a strong absorption function for ultraviolet light below 250nm, ensuring the growth of plants.

[0032] Among them, the preparation method of the modified ethylene-vinyl acetate copolymer is: a modifier with a siloxane structure containing carbon-carbon double bonds at both ends is prepared by a hydrosilylation reaction of tetramethyldisilane and allyl methacrylate, and the modified siloxane structure is introduced into the chain segment of the ethylene-vinyl acetate copolymer by a melt grafting method to obtain a modified vinyl acetate copolymer.

[0033] Among them, a modifier with a siloxane structure containing carbon-carbon double bonds at both ends was introduced by the melt grafting method, so that the ethylene-vinyl acetate copolymer formed a network structure, which improved the tensile strength. At the same time, its similar silicon-oxygen structure helped the anti-fog agent to be evenly dispersed in the network structure, reducing the possibility of agglomeration and enhancing the uniformity of the composite film. When the mass ratio of the anti-fog agent masterbatch to the ethylene-vinyl acetate copolymer was 1:1.5~2, the comprehensive performance was optimal. DETAILED DESCRIPTION

[0034] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0035] It should be noted that the following parts are calculated by weight, and the purchase manufacturers of all raw materials involved in the present invention are not particularly restricted. Examples include: CAS number of glyceryl monostearate: 123-94-4; CAS number of 3-(isomethylacryloyloxy)propyltrimethoxysilane: 2530-85-0; CAS number of tetraethyl orthosilicate: 562-90-3; nano-alumina with a particle size of 10-40 nm; CAS number of hexadecyltrimethylammonium bromide: 57-09-0; CAS number of tetramethyldisilane: 30110-74-8; Karsedt catalyst, provided by Beijing Huawei Ruike Chemical Technology Co., Ltd.; CAS number of allyl methacrylate: 96-05-9; ethylene-vinyl acetate copolymer, model EF443, provided by Dongguan Koside Plastic Technology Co., Ltd.; CAS number of dicumyl peroxide: 80-43-3.

[0036] In the following examples, parts are by mass, and the above-mentioned and other raw materials used but not mentioned are commercially available.

[0037] Among them, in each embodiment and comparative example, the antioxidant accounts for 6wt% of the antioxidant masterbatch, and the rest is the matrix masterbatch; the rheological agent accounts for 3wt% of the rheological agent masterbatch, and the rest is the matrix masterbatch; in the splitter masterbatch, the splitter accounts for 14wt%, and the rest is the matrix masterbatch; the splitter includes a red-orange light additive, a fluorescent agent, a dispersant, a yellow pigment, and a red pigment in a mass ratio of 10:0.5:0.8:0.02:0.04; the matrix masterbatch is LLDPE, model DFDA-9020, provided by Tianjin United Chemical Co., Ltd.

[0038] Example 1: The preparation method of the spectral greenhouse composite film comprises the following steps:

[0039] Step 1: Preparation of antifogging agent: (1) 6 parts of glyceryl monostearate, 3.5 parts of 3-(isobutyleneoxy)propyltrimethoxysilane and 0.04-0.05 parts of triethylamine were mixed evenly, stirred at 100°C for 3.5 hours, filtered, washed with anhydrous ethanol, and dried to obtain modified glyceryl monostearate;

[0040] (2) Add 6.5 parts of tetraethyl orthosilicate to 20 parts of 30% ethanol solution, adjust the pH to 6, and stir at 55°C for 1 hour to obtain silica sol;

[0041] (3) Add 2 parts of nano-alumina to 55 parts of 30% ethanol solution and disperse uniformly by ultrasonication, add 0.8 parts of modified monostearate glyceryl and 0.5 parts of cetyltrimethylammonium bromide, stir at 45°C for 1 hour, add 25 parts of silica sol, adjust the pH to 8, stir at 65°C for 7 hours, let stand for 24 hours, filter, wash, and dry to obtain an anti-fog agent;

[0042] Step 2: Preparation of modified ethylene-vinyl acetate copolymer: 1.35 parts of tetramethyldisilane, 0.03 parts of Karsedt catalyst, and 2.55 parts of allyl methacrylate were mixed uniformly, stirred at 75° C. for 2.5 hours, and purified to obtain a modifier;

[0043] (2) 40 parts of ethylene-vinyl acetate copolymer, 0.04 parts of dicumyl peroxide, and 2.5 parts of modifier were premixed and then added into a twin-screw extruder and melt-stirred at 175°C and a speed of 55 r / min for 10 minutes, extruded into pellets, and purified to obtain a modified ethylene-vinyl acetate copolymer;

[0044] Step 3: Preparation of spectral greenhouse composite film:

[0045] S1: According to the formula, each raw material and the base masterbatch are mixed in sequence, extruded and granulated to obtain the corresponding masterbatch;

[0046] S2: Blend the raw materials in order according to the recipe of the surface layer, middle layer and inner layer, use a three-layer film blowing machine for co-extrusion, the extrusion temperature is 200℃, plasticize into film, and dry at 85℃ to obtain a spectroscopic greenhouse composite film;

[0047] Among them, the surface layer includes the following raw materials, calculated in 100 parts by mass: 7 parts of antioxidant masterbatch, 2.5 parts of rheological agent masterbatch, 2.5 parts of splitter masterbatch, and the rest are matrix masterbatch; the middle layer includes the following raw materials, calculated in 100 parts by mass: 7 parts of antioxidant masterbatch, 2.5 parts of rheological agent masterbatch, 2.5 parts of splitter masterbatch, 14 parts of antifog agent masterbatch, 21 parts of ethylene-vinyl acetate copolymer, and the rest are matrix masterbatch; the inner layer includes the following raw materials, calculated in 100 parts by mass: 7 parts of antioxidant masterbatch, 2.5 parts of rheological agent masterbatch, 14 parts of antifog agent masterbatch, 21 parts of ethylene-vinyl acetate copolymer, and the rest are matrix masterbatch; the ethylene-vinyl acetate copolymer includes 35wt% of modified ethylene-vinyl acetate copolymer.

[0048] Example 2: The preparation method of the spectral greenhouse composite film comprises the following steps:

[0049] Step 1: Preparation of antifogging agent: (1) 6 parts of glyceryl monostearate, 3.5 parts of 3-(isobutyleneoxy)propyltrimethoxysilane and 0.04-0.05 parts of triethylamine were mixed evenly, stirred at 100°C for 3.5 hours, filtered, washed with anhydrous ethanol, and dried to obtain modified glyceryl monostearate;

[0050] (2) Add 6.5 parts of tetraethyl orthosilicate to 20 parts of 30% ethanol solution, adjust the pH to 6, and stir at 55°C for 1 hour to obtain silica sol;

[0051] (3) Add 2 parts of nano-alumina to 55 parts of 30% ethanol solution and disperse uniformly by ultrasonication, add 0.8 parts of modified monostearate glyceryl and 0.5 parts of cetyltrimethylammonium bromide, stir at 45°C for 1 hour, add 25 parts of silica sol, adjust the pH to 8, stir at 65°C for 7 hours, let stand for 24 hours, filter, wash, and dry to obtain an anti-fog agent;

[0052] Step 2: Preparation of modified ethylene-vinyl acetate copolymer: 1.35 parts of tetramethyldisilane, 0.03 parts of Karsedt catalyst, and 2.55 parts of allyl methacrylate were mixed uniformly, stirred at 75° C. for 2.5 hours, and purified to obtain a modifier;

[0053] (2) 40 parts of ethylene-vinyl acetate copolymer, 0.04 parts of dicumyl peroxide, and 2.5 parts of modifier were premixed and then added into a twin-screw extruder and melt-stirred at 175°C and a speed of 55 r / min for 10 minutes, extruded into pellets, and purified to obtain a modified ethylene-vinyl acetate copolymer;

[0054] Step 3: Preparation of spectral greenhouse composite film:

[0055] S1: According to the formula, each raw material and the base masterbatch are mixed in sequence, extruded and granulated to obtain the corresponding masterbatch;

[0056] S2: Blend the raw materials in order according to the recipe of the surface layer, middle layer and inner layer, use a three-layer film blowing machine for co-extrusion, the extrusion temperature is 200℃, plasticize into film, and dry at 85℃ to obtain a spectroscopic greenhouse composite film;

[0057] Among them, the surface layer includes the following raw materials, calculated in 100 parts by mass: 6 parts of antioxidant masterbatch, 2 parts of rheological agent masterbatch, 2 parts of splitter masterbatch, and the rest are matrix masterbatch; the middle layer includes the following raw materials, calculated in 100 parts by mass: 6 parts of antioxidant masterbatch, 2 parts of rheological agent masterbatch, 2 parts of splitter masterbatch, 12 parts of antifog agent masterbatch, 24 parts of ethylene-vinyl acetate copolymer, and the rest are matrix masterbatch; the inner layer includes the following raw materials, calculated in 100 parts by mass: 6 parts of antioxidant masterbatch, 2 parts of rheological agent masterbatch, 12 parts of antifog agent masterbatch, 24 parts of ethylene-vinyl acetate copolymer, and the rest are matrix masterbatch; the ethylene-vinyl acetate copolymer includes 35wt% of modified ethylene-vinyl acetate copolymer.

[0058] Example 3: The preparation method of the spectral greenhouse composite film comprises the following steps:

[0059] Step 1: Preparation of antifogging agent: (1) 6 parts of glyceryl monostearate, 3.5 parts of 3-(isobutyleneoxy)propyltrimethoxysilane and 0.04-0.05 parts of triethylamine were mixed evenly, stirred at 100°C for 3.5 hours, filtered, washed with anhydrous ethanol, and dried to obtain modified glyceryl monostearate;

[0060] (2) Add 6.5 parts of tetraethyl orthosilicate to 20 parts of 30% ethanol solution, adjust the pH to 6, and stir at 55°C for 1 hour to obtain silica sol;

[0061] (3) Add 2 parts of nano-alumina to 55 parts of 30% ethanol solution and disperse uniformly by ultrasonication, add 0.8 parts of modified monostearate glyceryl and 0.5 parts of cetyltrimethylammonium bromide, stir at 45°C for 1 hour, add 25 parts of silica sol, adjust the pH to 8, stir at 65°C for 7 hours, let stand for 24 hours, filter, wash, and dry to obtain an anti-fog agent;

[0062] Step 2: Preparation of modified ethylene-vinyl acetate copolymer: 1.35 parts of tetramethyldisilane, 0.03 parts of Karsedt catalyst, and 2.55 parts of allyl methacrylate were mixed uniformly, stirred at 75° C. for 2.5 hours, and purified to obtain a modifier;

[0063] (2) 40 parts of ethylene-vinyl acetate copolymer, 0.04 parts of dicumyl peroxide, and 2.5 parts of modifier were premixed and then added into a twin-screw extruder and melt-stirred at 175°C and a speed of 55 r / min for 10 minutes, extruded into pellets, and purified to obtain a modified ethylene-vinyl acetate copolymer;

[0064] Step 3: Preparation of spectral greenhouse composite film:

[0065] S1: According to the formula, each raw material and the base masterbatch are mixed in sequence, extruded and granulated to obtain the corresponding masterbatch;

[0066] S2: Blend the raw materials in order according to the recipe of the surface layer, middle layer and inner layer, use a three-layer film blowing machine for co-extrusion, the extrusion temperature is 200℃, plasticize into film, and dry at 85℃ to obtain a spectroscopic greenhouse composite film;

[0067] Among them, the surface layer includes the following raw materials, calculated in 100 parts by mass: 8 parts of antioxidant masterbatch, 3 parts of rheological agent masterbatch, 3 parts of spectrometer masterbatch, and the rest are matrix masterbatch; the middle layer includes the following raw materials, calculated in 100 parts by mass: 8 parts of antioxidant masterbatch, 3 parts of rheological agent masterbatch, 3 parts of spectrometer masterbatch, 16 parts of anti-fog agent masterbatch, 24 parts of ethylene-vinyl acetate copolymer, and the rest are matrix masterbatch; the inner layer includes the following raw materials, calculated in 100 parts by mass: 8 parts of antioxidant masterbatch, 3 parts of rheological agent masterbatch, 16 parts of anti-fog agent masterbatch, 24 parts of ethylene-vinyl acetate copolymer, and the rest are matrix masterbatch; the ethylene-vinyl acetate copolymer includes 35wt% of modified ethylene-vinyl acetate copolymer.

[0068] Comparative Example 1: Based on Example 1, the antifogging agent was directly added, and the other processes remained unchanged, as follows:

[0069] Step 1: Preparation of antifogging agent: (1) Mix 6 parts of glyceryl monostearate and 3.5 parts of 3-(isobutyleneoxy)propyltrimethoxysilane, stir at 100°C for 3.5 hours, filter, wash with anhydrous ethanol, and dry to obtain an antifogging agent;

[0070] Step 2: Preparation of modified ethylene-vinyl acetate copolymer: 1.35 parts of tetramethyldisilane, 0.03 parts of Karsedt catalyst, and 2.55 parts of allyl methacrylate were mixed uniformly, stirred at 75° C. for 2.5 hours, and purified to obtain a modifier;

[0071] (2) 40 parts of ethylene-vinyl acetate copolymer, 0.04 parts of dicumyl peroxide, and 2.5 parts of modifier were premixed and then added into a twin-screw extruder and melt-stirred at 175°C and a speed of 55 r / min for 10 minutes, extruded into pellets, and purified to obtain a modified ethylene-vinyl acetate copolymer;

[0072] Step 3: Preparation of spectral greenhouse composite film:

[0073] S1: According to the formula, each raw material and the base masterbatch are mixed in sequence, extruded and granulated to obtain the corresponding masterbatch;

[0074] S2: Blend the raw materials in order according to the recipe of the surface layer, middle layer and inner layer, use a three-layer film blowing machine for co-extrusion, the extrusion temperature is 200℃, plasticize into film, and dry at 85℃ to obtain a spectroscopic greenhouse composite film;

[0075] Among them, the surface layer includes the following raw materials, calculated in 100 parts by mass: 7 parts of antioxidant masterbatch, 2.5 parts of rheological agent masterbatch, 2.5 parts of splitter masterbatch, and the rest are matrix masterbatch; the middle layer includes the following raw materials, calculated in 100 parts by mass: 7 parts of antioxidant masterbatch, 2.5 parts of rheological agent masterbatch, 2.5 parts of splitter masterbatch, 14 parts of antifog agent masterbatch, 21 parts of ethylene-vinyl acetate copolymer, and the rest are matrix masterbatch; the inner layer includes the following raw materials, calculated in 100 parts by mass: 7 parts of antioxidant masterbatch, 2.5 parts of rheological agent masterbatch, 14 parts of antifog agent masterbatch, 21 parts of ethylene-vinyl acetate copolymer, and the rest are matrix masterbatch; the ethylene-vinyl acetate copolymer includes 35wt% of modified ethylene-vinyl acetate copolymer.

[0076] Comparative Example 2: Based on Example 1, silica sol wrapping was not used, and the other processes remained unchanged, as follows:

[0077] Step 1: Preparation of antifogging agent: (1) 6 parts of glyceryl monostearate, 3.5 parts of 3-(isobutyleneoxy)propyltrimethoxysilane and 0.04-0.05 parts of triethylamine were mixed evenly, stirred at 100°C for 3.5 hours, filtered, washed with anhydrous ethanol, and dried to obtain modified glyceryl monostearate;

[0078] (2) Add 2 parts of nano-alumina to 55 parts of 30% ethanol solution and disperse uniformly by ultrasonication, add 0.8 parts of modified monostearate glyceryl and 0.5 parts of cetyltrimethylammonium bromide, stir at 45°C for 1 hour, filter, wash, and dry to obtain an antifogging agent;

[0079] Step 2: Preparation of modified ethylene-vinyl acetate copolymer: 1.35 parts of tetramethyldisilane, 0.03 parts of Karsedt catalyst, and 2.55 parts of allyl methacrylate were mixed uniformly, stirred at 75° C. for 2.5 hours, and purified to obtain a modifier;

[0080] (2) 40 parts of ethylene-vinyl acetate copolymer, 0.04 parts of dicumyl peroxide, and 2.5 parts of modifier were premixed and then added into a twin-screw extruder and melt-stirred at 175°C and a speed of 55 r / min for 10 minutes, extruded into pellets, and purified to obtain a modified ethylene-vinyl acetate copolymer;

[0081] Step 3: Preparation of spectral greenhouse composite film:

[0082] S1: According to the formula, each raw material and the base masterbatch are mixed in sequence, extruded and granulated to obtain the corresponding masterbatch;

[0083] S2: Blend the raw materials in order according to the recipe of the surface layer, middle layer and inner layer, use a three-layer film blowing machine for co-extrusion, the extrusion temperature is 200℃, plasticize into film, and dry at 85℃ to obtain a spectroscopic greenhouse composite film;

[0084] Among them, the surface layer includes the following raw materials, calculated in 100 parts by mass: 7 parts of antioxidant masterbatch, 2.5 parts of rheological agent masterbatch, 2.5 parts of splitter masterbatch, and the rest are matrix masterbatch; the middle layer includes the following raw materials, calculated in 100 parts by mass: 7 parts of antioxidant masterbatch, 2.5 parts of rheological agent masterbatch, 2.5 parts of splitter masterbatch, 14 parts of antifog agent masterbatch, 21 parts of ethylene-vinyl acetate copolymer, and the rest are matrix masterbatch; the inner layer includes the following raw materials, calculated in 100 parts by mass: 7 parts of antioxidant masterbatch, 2.5 parts of rheological agent masterbatch, 14 parts of antifog agent masterbatch, 21 parts of ethylene-vinyl acetate copolymer, and the rest are matrix masterbatch; the ethylene-vinyl acetate copolymer includes 35wt% of modified ethylene-vinyl acetate copolymer.

[0085] Comparative Example 3: Based on Example 1, the ethylene-vinyl acetate copolymer was not modified and the other processes remained unchanged, as follows:

[0086] Step 1: Preparation of antifogging agent: (1) 6 parts of glyceryl monostearate, 3.5 parts of 3-(isobutyleneoxy)propyltrimethoxysilane and 0.04-0.05 parts of triethylamine were mixed evenly, stirred at 100°C for 3.5 hours, filtered, washed with anhydrous ethanol, and dried to obtain modified glyceryl monostearate;

[0087] (2) Add 6.5 parts of tetraethyl orthosilicate to 20 parts of 30% ethanol solution, adjust the pH to 6, and stir at 55°C for 1 hour to obtain silica sol;

[0088] (3) Add 2 parts of nano-alumina to 55 parts of 30% ethanol solution and disperse uniformly by ultrasonication, add 0.8 parts of modified monostearate glyceryl and 0.5 parts of cetyltrimethylammonium bromide, stir at 45°C for 1 hour, add 25 parts of silica sol, adjust the pH to 8, stir at 65°C for 7 hours, let stand for 24 hours, filter, wash, and dry to obtain an anti-fog agent;

[0089] Step 2: Preparation of spectral greenhouse composite film:

[0090] S1: According to the formula, each raw material and the base masterbatch are mixed in sequence, extruded and granulated to obtain the corresponding masterbatch;

[0091] S2: Blend the raw materials in order according to the recipe of the surface layer, middle layer and inner layer, use a three-layer film blowing machine for co-extrusion, the extrusion temperature is 200℃, plasticize into film, and dry at 85℃ to obtain a spectroscopic greenhouse composite film;

[0092] Among them, the surface layer includes the following raw materials, calculated based on 100 parts by mass: 7 parts of antioxidant masterbatch, 2.5 parts of rheological agent masterbatch, 2.5 parts of splitter masterbatch, and the rest are matrix masterbatch; the middle layer includes the following raw materials, calculated based on 100 parts by mass: 7 parts of antioxidant masterbatch, 2.5 parts of rheological agent masterbatch, 2.5 parts of splitter masterbatch, 14 parts of antifog agent masterbatch, 21 parts of ethylene-vinyl acetate copolymer, and the rest are matrix masterbatch; the inner layer includes the following raw materials, calculated based on 100 parts by mass: 7 parts of antioxidant masterbatch, 2.5 parts of rheological agent masterbatch, 14 parts of antifog agent masterbatch, 21 parts of ethylene-vinyl acetate copolymer, and the rest are matrix masterbatch.

[0093] Comparative Example 4: Based on Example 1, the amount of anti-fogging agent masterbatch added was increased, and the other processes remained unchanged, as follows:

[0094] Step 1: Preparation of antifogging agent: (1) 6 parts of glyceryl monostearate, 3.5 parts of 3-(isobutyleneoxy)propyltrimethoxysilane and 0.04-0.05 parts of triethylamine were mixed evenly, stirred at 100°C for 3.5 hours, filtered, washed with anhydrous ethanol, and dried to obtain modified glyceryl monostearate;

[0095] (2) Add 6.5 parts of tetraethyl orthosilicate to 20 parts of 30% ethanol solution, adjust the pH to 6, and stir at 55°C for 1 hour to obtain silica sol;

[0096] (3) Add 2 parts of nano-alumina to 55 parts of 30% ethanol solution and disperse uniformly by ultrasonication, add 0.8 parts of modified monostearate glyceryl and 0.5 parts of cetyltrimethylammonium bromide, stir at 45°C for 1 hour, add 25 parts of silica sol, adjust the pH to 8, stir at 65°C for 7 hours, let stand for 24 hours, filter, wash, and dry to obtain an anti-fog agent;

[0097] Step 2: Preparation of modified ethylene-vinyl acetate copolymer: 1.35 parts of tetramethyldisilane, 0.03 parts of Karsedt catalyst, and 2.55 parts of allyl methacrylate were mixed uniformly, stirred at 75° C. for 2.5 hours, and purified to obtain a modifier;

[0098] (2) 40 parts of ethylene-vinyl acetate copolymer, 0.04 parts of dicumyl peroxide, and 2.5 parts of modifier were premixed and then added into a twin-screw extruder and melt-stirred at 175°C and a speed of 55 r / min for 10 minutes, extruded into pellets, and purified to obtain a modified ethylene-vinyl acetate copolymer;

[0099] Step 3: Preparation of spectral greenhouse composite film:

[0100] S1: According to the formula, each raw material and the base masterbatch are mixed in sequence, extruded and granulated to obtain the corresponding masterbatch;

[0101] S2: Blend the raw materials in order according to the recipe of the surface layer, middle layer and inner layer, use a three-layer film blowing machine for co-extrusion, the extrusion temperature is 200℃, plasticize into film, and dry at 85℃ to obtain a spectroscopic greenhouse composite film;

[0102] Among them, the surface layer includes the following raw materials, calculated in 100 parts by mass: 7 parts of antioxidant masterbatch, 2.5 parts of rheological agent masterbatch, 2.5 parts of splitter masterbatch, and the rest are matrix masterbatch; the middle layer includes the following raw materials, calculated in 100 parts by mass: 7 parts of antioxidant masterbatch, 2.5 parts of rheological agent masterbatch, 2.5 parts of splitter masterbatch, 21 parts of antifog agent masterbatch, 21 parts of ethylene-vinyl acetate copolymer, and the rest are matrix masterbatch; the inner layer includes the following raw materials, calculated in 100 parts by mass: 7 parts of antioxidant masterbatch, 2.5 parts of rheological agent masterbatch, 14 parts of antifog agent masterbatch, 21 parts of ethylene-vinyl acetate copolymer, and the rest are matrix masterbatch; the ethylene-vinyl acetate copolymer includes 35wt% of modified ethylene-vinyl acetate copolymer.

[0103] Performance test: (1) According to GB / T 31726-2015, the samples prepared in Examples 1 to 3 and Comparative Examples 1 to 4 were subjected to the water bath hot fog method to test the anti-fog performance. The test temperature was 60°C and the test time was 1 to 84 hours. The water droplets on the surface of the film layer were observed and evaluated according to A to E (A is completely opaque and the eye chart cannot be seen clearly; B is translucent and there are many small water droplets. A small amount of less than 0.1 on the eye chart can be seen; C is basically transparent and there are more water droplets. The font of the eye chart is deformed; D is relatively transparent and there are a small amount of uneven large water droplets. The clarity of the eye chart of more than 50% of the area is completely consistent with that before the test; E is free of water droplets and the clarity of the eye chart is completely consistent with that before the test). The experimental data are shown in Table 1. (2) According to GB / T 2410-2008, the samples prepared in Examples 1 to 3 and Comparative Examples 1 to 4 were subjected to transmittance and haze tests. The experimental data are shown in Table 1. (3) According to GB / T 1040.3-2006 The tensile strength test was performed on the samples prepared in Examples 1 to 3 and Comparative Examples 1 to 4. The sample width was 15 mm. The experimental data are shown in Table 1.

[0104] Table 1

[0105]

[0106] As can be seen from Table 1, the spectroscopic greenhouse composite film prepared in this application has excellent anti-fog effect and anti-fog duration by introducing the prepared anti-fog agent and partially modified ethylene-vinyl acetate copolymer, and has high light transmittance, low haze and good mechanical properties, and therefore has good spectroscopic effect.

[0107] In Comparative Example 1, the antifog agent is directly added, and the antifog agent is easy to migrate, so it maintains good antifog performance before 12 hours, but the antifog performance gradually decreases thereafter, and the heterogeneous nucleation effect of nano-alumina is lacking, so the light transmittance decreases and the haze increases; in Comparative Example 2, no silica sol is used for packaging, and it has good antifog performance before 60 hours, and the anti-fog performance decreases significantly after 84 hours, indicating that relative to Comparative Example 1, the antifog agent is loaded and grafted on nano-alumina, which has a certain ability to reduce mobility, thereby increasing the anti-fog performance, but because silica sol is not used to package silica dioxide, and because the refractive index of alumina is different from that of polyethylene, the light transmittance and haze performance decrease; in Comparative Example 3, the ethylene-vinyl acetate copolymer is not modified, the dispersion compatibility of the antifog agent decreases, and the network structure is lacking, so the antifog performance decreases and the mechanical properties decrease; in Comparative Example 4, the amount of antifog agent masterbatch added is increased, which exceeds the dispersion ability of the modified ethylene-vinyl acetate copolymer, and agglomeration occurs, so the light transmittance and haze performance decrease.

[0108] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A spectral greenhouse composite film, characterized by: From top to bottom: surface layer, middle layer, inner layer; The surface layer comprises the following raw materials, calculated based on 100 parts by mass: 6 to 8 parts of antioxidant masterbatch, 2 to 3 parts of rheological agent masterbatch, 2 to 3 parts of splitter masterbatch, and the rest is matrix masterbatch; The intermediate layer comprises the following raw materials, calculated based on 100 parts by mass: 6 to 8 parts of antioxidant masterbatch, 2 to 3 parts of rheological agent masterbatch, 2 to 3 parts of splitter masterbatch, 12 to 16 parts of antifogging agent masterbatch, 18 to 24 parts of ethylene-vinyl acetate copolymer, and the rest is matrix masterbatch; The inner layer comprises the following raw materials, calculated based on 100 parts by mass: 6 to 8 parts of antioxidant masterbatch, 2 to 3 parts of rheological agent masterbatch, 12 to 16 parts of antifogging agent masterbatch, 18 to 24 parts of ethylene-vinyl acetate copolymer, and the rest is matrix masterbatch; Wherein, the ethylene-vinyl acetate copolymer includes 30-40 wt% of a modified ethylene-vinyl acetate copolymer; The preparation method of the modified ethylene-vinyl acetate copolymer comprises the following steps: (1) uniformly mixing tetramethyldisilane, Karsedt catalyst, and allyl methacrylate, stirring at 70-80° C. for 2-3 hours, and purifying to obtain a modifier; (2) Ethylene-vinyl acetate copolymer, dicumyl peroxide, and modifier were premixed and then added into a twin-screw extruder, melt-stirred at 170-180°C and a speed of 50-60 r / min for 10-15 minutes, extruded into pellets, and purified to obtain modified ethylene-vinyl acetate copolymer; The modifier comprises the following raw materials, calculated by mass: 1.3-1.4 parts of tetramethyldisilane, 0.03-0.04 parts of Karsedt catalyst, and 2.5-2.6 parts of allyl methacrylate; The modified ethylene-vinyl acetate copolymer comprises the following raw materials, calculated by mass: 38-40 parts of ethylene-vinyl acetate copolymer, 0.03-0.05 parts of dicumyl peroxide, and 2-3 parts of a modifier; The antifogging agent accounts for 50-60 wt% of the antifogging agent masterbatch, and the rest is the matrix masterbatch; the mass ratio of the antifogging agent masterbatch to the ethylene-vinyl acetate copolymer is 1:1.5-2; The preparation method of the anti-fog agent comprises the following steps: (1) uniformly mixing glyceryl monostearate, 3-(isomethacryloyloxy)propyltrimethoxysilane and triethylamine, stirring at 100-105° C. for 3-4 hours, filtering, washing with anhydrous ethanol, and drying to obtain modified glyceryl monostearate; (3) Add tetraethyl orthosilicate to a 30% ethanol solution, adjust the pH to 6, and stir at 50-60°C for 1-1.5 hours to obtain a silica sol; (4) Add nano-alumina to 30% ethanol solution and disperse it evenly by ultrasonication. Add modified monostearate glyceryl and cetyltrimethylammonium bromide and stir at 40-50°C for 1-1.5 hours. Add 25-30 parts of silica sol and adjust the pH to 8. Stir at 60-70°C for 6-8 hours. Let it stand for 24-36 hours, filter, wash and dry to obtain an anti-fog agent.

2. The spectral greenhouse composite film according to claim 1, characterized in that: The modified glyceryl monostearate comprises the following raw materials, calculated by mass: 5.5-6.5 parts of glyceryl monostearate, 3-4 parts of 3-(methacryloyloxy)propyltrimethoxysilane, and 0.04-0.05 parts of triethylamine; The silica sol comprises the following raw materials, calculated by mass: 5-8 parts of tetraethyl orthosilicate, 18-20 parts of 30% ethanol solution; The anti-fog agent comprises the following raw materials, calculated by mass: 1-3 parts of nano-alumina, 50-60 parts of 30% ethanol solution, 0.6-1 parts of modified monostearate, 0.4-0.6 parts of cetyltrimethylammonium bromide, and 25-30 parts of silica sol.

3. The spectral greenhouse composite film according to claim 1, characterized in that: The antioxidant masterbatch contains 6-7wt% of the antioxidant, and the rest is the matrix masterbatch; the rheological agent masterbatch contains 3-4wt% of the rheological agent, and the rest is the matrix masterbatch; the splitter masterbatch contains 12-15wt% of the splitter, and the rest is the matrix masterbatch; The splitter includes a red-orange light additive, a fluorescent agent, a dispersant, a yellow pigment, and a red pigment in a mass ratio of 10:0.5:0.8:0.02:0.04; The matrix masterbatch includes one or both of LLDPE and mLLDPE.

4. A method for preparing a spectral greenhouse composite film according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1: According to the formula, each raw material and the base masterbatch are mixed in sequence, extruded and granulated to obtain the corresponding masterbatch; S2: Blend the raw materials in sequence according to the formula of the surface layer, the middle layer and the inner layer, use a three-layer film blowing machine to co-extrude, plasticize into a film, and dry to obtain a spectroscopic greenhouse composite film.

5. The method for preparing a spectral greenhouse composite film according to claim 4, characterized in that: During the co-extrusion process, the extrusion temperature is 190-220° C.; during the drying process, the drying temperature is 80-90° C.; and the thickness of the spectroscopic greenhouse composite film is 80-100 μm.

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