WO2020248514A1 - 一种农用膜及其制备方法 - Google Patents

一种农用膜及其制备方法 Download PDF

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WO2020248514A1
WO2020248514A1 PCT/CN2019/119600 CN2019119600W WO2020248514A1 WO 2020248514 A1 WO2020248514 A1 WO 2020248514A1 CN 2019119600 W CN2019119600 W CN 2019119600W WO 2020248514 A1 WO2020248514 A1 WO 2020248514A1
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parts
film
agricultural film
agent
pvc
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PCT/CN2019/119600
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English (en)
French (fr)
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熊圣东
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宁波先锋新材料股份有限公司
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Publication of WO2020248514A1 publication Critical patent/WO2020248514A1/zh

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    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01G—HORTICULTURE; CULTIVATION OF VEGETABLES, FLOWERS, RICE, FRUIT, VINES, HOPS OR SEAWEED; FORESTRY; WATERING
    • A01G13/00—Protecting plants
    • A01G13/02—Protective coverings for plants; Coverings for the ground; Devices for laying-out or removing coverings
    • A01G13/0256—Ground coverings
    • A01G13/0268—Mats or sheets, e.g. nets or fabrics
    • A01G13/0275—Films
    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01G—HORTICULTURE; CULTIVATION OF VEGETABLES, FLOWERS, RICE, FRUIT, VINES, HOPS OR SEAWEED; FORESTRY; WATERING
    • A01G9/00—Cultivation in receptacles, forcing-frames or greenhouses; Edging for beds, lawn or the like
    • A01G9/14—Greenhouses
    • A01G9/1438—Covering materials therefor; Materials for protective coverings used for soil and plants, e.g. films, canopies, tunnels or cloches
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
    • C08J7/04—Coating
    • C08J7/042—Coating with two or more layers, where at least one layer of a composition contains a polymer binder
    • C08J7/0423—Coating with two or more layers, where at least one layer of a composition contains a polymer binder with at least one layer of inorganic material and at least one layer of a composition containing a polymer binder
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L27/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers
    • C08L27/02—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L27/04—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment containing chlorine atoms
    • C08L27/06—Homopolymers or copolymers of vinyl chloride
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2327/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
    • C08J2327/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
    • C08J2327/04—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing chlorine atoms
    • C08J2327/06—Homopolymers or copolymers of vinyl chloride
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2427/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
    • C08J2427/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
    • C08J2427/04—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing chlorine atoms
    • C08J2427/06—Homopolymers or copolymers of vinyl chloride
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2467/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
    • C08J2467/08—Polyesters modified with higher fatty oils or their acids, or with resins or resin acids
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2201/00—Properties
    • C08L2201/08—Stabilised against heat, light or radiation or oxydation
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2201/00—Properties
    • C08L2201/10—Transparent films; Clear coatings; Transparent materials
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2205/00—Polymer mixtures characterised by other features
    • C08L2205/03—Polymer mixtures characterised by other features containing three or more polymers in a blend
    • C08L2205/035—Polymer mixtures characterised by other features containing three or more polymers in a blend containing four or more polymers in a blend
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A40/00—Adaptation technologies in agriculture, forestry, livestock or agroalimentary production
    • Y02A40/10—Adaptation technologies in agriculture, forestry, livestock or agroalimentary production in agriculture
    • Y02A40/25—Greenhouse technology, e.g. cooling systems therefor

Definitions

  • the invention relates to an agricultural film, in particular to a polyvinyl chloride composite agricultural film and a preparation method thereof, and belongs to the technical field of agriculture.
  • Agricultural film is an indispensable part of every country's agricultural products and has become the third largest agricultural production material after fertilizers and pesticides.
  • Agricultural film is a general term for plastic films used in agricultural production. It plays a very important role in moisturizing, heat preservation, photosynthesis, adjusting light, preventing weeds and insects, etc., and can accelerate crop growth, extend the growth period, increase production, etc. .
  • the commonly used agricultural film is made of polymer composite material by calendering or blow molding process, mainly including polyvinyl chloride (PVC) film, polyethylene (PE) film, ethylene-vinyl ester copolymer (EVA) film, And the use of PE, EVA as the main material of the multilayer (PO) film.
  • PVC agricultural film has become a major agricultural film because of its good mechanical strength, strong elasticity, good transparency and low price.
  • the traditional PVC agricultural film on the market at present will cause the film surface to absorb dust and poor self-cleaning due to the precipitation of the plasticizer in the soft PVC, which will seriously affect the light transmission performance of the film after a long time.
  • substances with anti-fogging function can be introduced into agricultural films, such as polyol fatty acid esters, alkylphenols, fluorine-containing or silicon-containing surfactants, etc., so that the mist in the shed can be on the surface of the film.
  • antifogging agent and dripping agent are mainly two methods for preparing this kind of non-drip film with dripping function: one is to add antifogging agent and dripping agent to the material for preparing agricultural film, and then extrusion calendering or blow molding into a film.
  • agricultural films not only require high light transmittance, but also require a certain haze to make the film have light scattering properties.
  • Agricultural film with light scattering properties can reduce direct glare and protect crops from being burned; on the other hand, scattered light can also irradiate the shaded crop parts that are not exposed to direct light, so that the agricultural film can cover the bottom.
  • the temperature and sunlight are more evenly distributed, crops can receive light in all directions, promote better photosynthesis of crops, and improve crop quality and yield.
  • the light transmittance and haze of the plastic film are mutually contradictory characteristics. As the haze value increases, the light transmittance will decrease.
  • publication number CN104441869A discloses a light-scattering agricultural film, which adds some inorganic light-scattering particles in the film: kaolin, diatomaceous earth, talc, hydrotalcite, sericite, barium sulfate, etc., but these inorganic additives are not only Decreasing the transparency of the film will also affect the mechanical properties of the film.
  • the present invention provides an agricultural film with high transparency, high light scattering, good self-cleaning, heat preservation, and anti-fogging performance, and a preparation method thereof.
  • An agricultural film includes: a PVC transparent base film layer, the two sides of the base film layer are respectively coated inner layer and surface layer.
  • the agricultural film of the present invention has a simple structure and composition, wherein the transparent PVC base film layer has light scattering properties, the coating inner layer is a transparent inner layer with anti-fogging dripping and heat preservation properties; the coating surface layer is a transparent surface with self-cleaning properties Floor.
  • the thickness of the agricultural film is 60-80 ⁇ m.
  • the PVC transparent base film layer in parts by weight, includes the following components: PVC resin: 90-110 parts, stabilizer: 3-5 parts, plasticizer: 40-55 parts, ethylene-acetic acid Ethylene copolymer: 2-4 parts, vinyl chloride grafted chlorinated polyethylene copolymer: 2-4 parts, lubricant: 1-1.5 parts, anti-ultraviolet agent: 0.4-1 part, light stabilizer: 0.2-0.5 part , Antioxidant: 0.4-1 part, brightener: 0.01-0.05 part.
  • PVC resin 90-110 parts
  • stabilizer 3-5 parts
  • plasticizer 40-55 parts
  • ethylene-acetic acid Ethylene copolymer 2-4 parts
  • vinyl chloride grafted chlorinated polyethylene copolymer 2-4 parts
  • lubricant 1-1.5 parts
  • anti-ultraviolet agent 0.4-1 part
  • light stabilizer 0.2-0.5 part
  • Antioxidant 0.4-1 part
  • brightener 0.01-0.05 part.
  • the average degree of polymerization of the PVC resin is 1200-1500.
  • the stabilizer includes 2.5-4 parts of main stabilizer and 0.5-1 part of auxiliary stabilizer.
  • the main stabilizer includes a calcium-zinc composite stabilizer
  • the auxiliary stabilizer includes triphenyl phosphite.
  • the triphenyl phosphite is used in combination with the calcium-zinc composite stabilizer, it can improve the heat resistance, transparency, pressure precipitation resistance, weather resistance and other practical performance of the product.
  • the plasticizer includes 35-40 parts of main plasticizer, 3-11 parts of auxiliary plasticizer, and 2-4 parts of epoxy soybean oil.
  • the main plasticizer includes a trimellitate plasticizer
  • the auxiliary plasticizer includes a fatty acid ester plasticizer
  • the main plasticizer includes one or more of trioctyl trimellitate, tris(n-octyl-n-decyl) trimellitate, and triglyceride trimellitate; and the auxiliary plasticizer includes One or more of dioctyl adipate, dioctyl sebacate, dioctyl azelate, and diisodecyl adipate.
  • plasticizers need to be added to the raw materials of PVC agricultural films, while traditional plasticizers, such as phthalates, are easy to precipitate. After a long time, the film surface is easy to absorb dust, and the self-cleaning property is poor, which seriously affects Film transmittance performance.
  • the present invention uses a trimellitate plasticizer with low volatility, low migration, good extraction resistance and good durability as the main plasticizer.
  • This type of plasticizer has the advantages of both monomeric plasticizers and polymeric plasticizers, and its compatibility with PVC and plasticizing efficiency are similar to phthalates.
  • Fatty acid ester plasticizers have good cold resistance. Agricultural films need to be placed in the environment day and night for a long time. The climate and temperature difference changes strongly.
  • a plasticizer with cold resistance is added to the PVC film and used in conjunction with the main plasticizer.
  • the agricultural film has good performance at low temperatures, and prolongs the service life of the agricultural film.
  • the combined use of epoxy soybean oil and trimellitate plasticizers can further prevent the latter from migrating outward.
  • the addition of epoxy soybean oil to the PVC composite material can also enhance the thermal stability of the PVC composite material. To the role of auxiliary stabilizer.
  • the vinyl acetate content is 25-40%; in the vinyl chloride grafted chlorinated polyethylene copolymer, the chlorinated polyethylene content is 50-65%, and the The chlorine content in polyethylene is 25-35%.
  • the main method for preparing films with light scattering properties is to add some inorganic light scattering particles to the film, such as kaolin, diatomaceous earth, talc, hydrotalcite, sericite, barium sulfate, etc. These inorganic additives will reduce the transparency of the film , Which reduces the light transmittance and also affects the mechanical properties of agricultural films.
  • the present invention uses organic resin ethylene-vinyl acetate copolymer (EVA) and vinyl chloride grafted chlorinated polyethylene copolymer (CPE-g-VC) with good light transmittance as light scattering agent, without reducing the total light transmission Realize light scattering under the premise of high rate.
  • EVA copolymer is made by copolymerization of ethylene and vinyl acetate. Due to the introduction of vinyl acetate monomer in the molecular chain, the crystallinity is reduced, the flexibility and impact resistance are improved. At the same time, because it contains both polarity and The non-polar segment makes it compatible with all kinds of polar and non-polar polymer materials.
  • CPE-g-VC is a graft copolymer resin made from chlorinated polyethylene (CPE) as the main chain and vinyl chloride (VC) monomer through graft polymerization. It has low temperature resistance, insulation, weather resistance, Good combustion resistance and good compatibility with polyvinyl chloride resin; and the CPE for preparing CPE-g-VC is a kind of random macromolecule chloride produced by chlorination of high-density polyethylene. Transparency. EVA and CPE-g-VC contain polar groups that are compatible with PVC to a certain extent, and also contain polyethylene groups that have poor compatibility with PVC but have light transmission properties.
  • CPE-g-VC copolymer After being dispersed and blended with PVC, These polyethylene groups with poor compatibility with PVC or the entire EVA, CPE-g-VC copolymer can be uniformly dispersed in the continuous phase of PVC, forming a three-dimensional continuous network "sea-island structure" with PVC . Because EVA, CPE-g-VC and PVC have different refractive indexes for light (the refractive index of PVC is about 1.539, the refractive index of EVA and CPE-g-VC used in the present invention is lower, 1.45-1.49), when light passes When the continuous PVC phase enters these "sea islands" with different refractive indexes, the light will change its original propagation direction and refraction will occur.
  • the continuous phase of PVC or the "sea island” phase of EVA and CPE-g-VC of the present invention allows light to pass through smoothly, which greatly guarantees the light transmission. Total transmittance.
  • the optical density and temperature distribution are consistent, and the light passing through the agricultural film is softly and uniformly scattered under the agricultural film and falls on the surface of the crop.
  • it can reduce strong direct light and protect crops from being burned; on the other hand, scattered light can also illuminate the shaded crop parts that are not exposed to direct light, making the temperature and sunlight distribution under the agricultural film cover more uniform. It can receive light in all directions, promote better photosynthesis of crops, and improve crop quality and yield.
  • the whitening agent includes a benzoxazole fluorescent whitening agent.
  • the fluorescent whitening agent can absorb the invisible ultraviolet light in the light, and convert it into longer-wavelength blue or violet visible light, to compensate for the yellowish color in the PVC matrix, and complementarily form white light, which increases the white light emitted by the PVC product, thereby weakening the PVC
  • the yellowish shortcomings of film products make the sensory more transparent and brighter.
  • the absorption of ultraviolet light by the brightener reduces the effect of ultraviolet light on the service life of the film, reduces the effect of ultraviolet light on crops, and reduces the occurrence of pests and diseases.
  • the lubricant includes monoglycerides of fatty acids.
  • Lubricants are mainly used to improve the processing flow properties of PVC, reduce the friction between PVC and processing equipment, and prevent PVC from adhering to metal processing equipment.
  • the mono-fatty acid glyceride not only plays the role of processing lubrication, but its surface activity also makes it have a certain dripping effect.
  • the coated inner layer in parts by weight, includes the following components: vinyl chloride-vinyl acetate copolymer resin solution: 90-110 parts, dripping agent 1.5-3.5 parts, anti-fogging agent 1.5-3.5 parts , 2-4 parts of heat insulating agent, 0.3-0.7 parts of leveling agent, 0.3-0.6 part of anti-ultraviolet agent, 0.3-0.6 part of antioxidant, 0.2-0.4 part of light stabilizer.
  • the solid content of the vinyl chloride-vinyl acetate copolymer resin solution is 30-50%.
  • Vinyl chloride-vinyl acetate copolymer resin (vinyl acetate copolymer resin) is a polymer prepared by copolymerizing vinyl chloride and vinyl acetate monomer. It has good compatibility with PVC and contains vinyl acetate groups with other additives in the inner layer. Has a good compatible coupling effect.
  • vinyl chloride copolymer resin as the base resin of the transparent inner layer, its good compatibility with PVC makes the transparent inner layer and the PVC base film layer more perfect integration, and solves the problem of anti-fogging dripping surfactant material coating liquid Poor compatibility with PVC base film, and the effect of anti-fogging and dripping gradually weakens over time, so it has the permanent effect of anti-fogging and dripping.
  • the vinyl acetate content in the vinyl chloride-vinyl acetate copolymer resin solution is 10-30%.
  • the dripping agent includes fatty acid polyoxyethylene ether, sodium lauryl sulfate, sodium lauryl sulfonate, fatty acid monoglyceride, octylphenol polyoxyethylene ether, and sorbitan fatty acid ester , One or more of coconut oil acid diethanolamide.
  • the dripping agent used in the present invention is a nonionic surfactant with a hydrophilic group and a hydrophobic group.
  • the hydrophobic group faces inward and the hydrophilic group faces outward, which improves the surface energy of the film;
  • the hydrophilic groups are arranged towards the inside of the water and the hydrophobic groups are arranged towards the outside, which can reduce the surface tension of the water.
  • the surface tension of water is reduced to equal to or less than the critical surface tension of the film, the water can spread on the surface of the film to form a water film instead of water droplets, thereby solving the problem of dripping.
  • the anti-fogging agent is a fluorine-containing surfactant, which may be produced by DuPont FS-65, FS-60, FS-63, FS-22, One or more of FS-3100.
  • the temperature inside and outside the agricultural film changes greatly.
  • the humidity is relatively high.
  • the decrease in temperature will cause the water vapor in the shed to reach supersaturation and condense into fine droplets.
  • the speed of forming fog droplets is greater than the speed of eliminating fog, the fog will diffuse, which will seriously hinder the penetration of sunlight.
  • the dripping agent can flatten the water droplets into a water film, they will form a tight arrangement in the water film after being dissolved in the water layer, and the hydrophobic groups will face outwards, which hinders the absorption of mist by the water film. Therefore, the dripping agent only has the function of dripping, and can not effectively eliminate the mist.
  • the present invention uses a fluorine-containing surfactant with strong surface activity as an anti-fogging agent, which can further reduce the surface tension of water, so that the water film spreads into a thinner water layer and flows to the ground faster, thereby improving the water layer The efficiency of absorbing droplets.
  • a fluorine-containing surfactant with strong surface activity as an anti-fogging agent, which can further reduce the surface tension of water, so that the water film spreads into a thinner water layer and flows to the ground faster, thereby improving the water layer The efficiency of absorbing droplets.
  • due to the hydrophobic and oil-repellent properties of the fluorine-containing antifogging agent due to the hydrophobic and oil-repellent properties of the fluorine-containing antifogging agent, its space occupancy effect disrupts the orderly arrangement of the dripping agent on the water film-air interface, thereby increasing the probability that the mist adheres to the water film , Improve the fog elimination ability.
  • the mist near the inner surface of the shed film can be quickly captured to form a thinner water film and flow down the surface of the film, when the water vapor near the shed film changes from supersaturation to unsaturated, the mist will disappear. At the same time, because the balance is broken, the mist in the film will diffuse and migrate to the vicinity of the film and continue to be captured and adhered. Therefore, even if the temperature in the film decreases, the water vapor in the film can be in an unsaturated state, thereby achieving the effect of eliminating the mist.
  • the heat insulating agent includes nano-sized cesium tungstate.
  • Nano-Cesium Tungstate has strong absorption characteristics in the near-infrared region of 800-1100nm, which can inhibit the infrared heat emitted by the plants under the agricultural film, reduce the heat loss under the agricultural film at night, have heat insulation effect, and accelerate the growth of crops; At the same time, it also weakened the impact of the high temperature of the sun at noon during the day on crop growth.
  • cesium tungstate has strong transmission characteristics in the visible light region, and does not affect the transmittance of sunlight, and cesium tungstate also has strong shielding characteristics for 200-380nm ultraviolet light, which is not only beneficial to the film’s resistance to ultraviolet aging, It can further reduce the amount of ultraviolet rays entering under the agricultural film and reduce the occurrence of pests and diseases.
  • the coating surface layer in parts by weight, includes the following components: vinyl chloride-vinyl acetate copolymer resin solution: 30-50 parts, acrylic modified alkyd resin solution 30-50 parts, fluorocarbon coating 1-2 parts, 0.1-0.2 parts of hexamethylene diisocyanate, 0.05-0.15 parts of titanium dioxide, 0.3-0.6 parts of leveling agent, 0.4-0.7 parts of anti-ultraviolet agent, 0.4-0.7 parts of antioxidant, 0.2 part of light stabilizer -0.5 copies.
  • vinyl chloride-vinyl acetate copolymer resin solution 30-50 parts
  • acrylic modified alkyd resin solution 30-50 parts
  • fluorocarbon coating 1-2 parts 0.1-0.2 parts of hexamethylene diisocyanate
  • 0.05-0.15 parts of titanium dioxide 0.05-0.15 parts
  • leveling agent 0.4-0.7 parts of anti-ultraviolet agent
  • 0.4-0.7 parts of antioxidant 0.2 part of light stabilizer -0.5 copies.
  • Acrylic modified alkyd resin not only retains the characteristics of good fullness and easy construction of alkyd resin, but also inherits the characteristics of thermoplastic acrylate resin such as fast drying, high transparency, excellent color retention and outdoor weather resistance, and enhances weather resistance performance.
  • thermoplastic acrylate resin such as fast drying, high transparency, excellent color retention and outdoor weather resistance, and enhances weather resistance performance.
  • the excellent compatibility of the vinyl chloride-vinyl acetate copolymer resin and the PVC base film makes it play a role in increasing the adhesion in the surface layer, so that the self-cleaning surface layer can be better integrated with the PVC base film.
  • the addition of anti-ultraviolet agents and antioxidants can slow down the decomposition and aging of polymer plastics and extend their service life.
  • the solid content of the acrylic modified alkyd resin solution is 30-50%.
  • the vinyl acetate content is 10-30%; in the acrylic modified alkyd resin, the acrylic component content is 20-60%.
  • the fluorocarbon coating may be Daikin's ZEFFLE series fluorocarbon coating, such as GK-570 and GK-510.
  • the fluorocarbon coating used in the present invention is a copolymer of tetrafluoroethylene and vinyl monomer. Under the action of the curing agent of hexamethylene diisocyanate, it can be quickly cured to form a film. When the film is formed, its fluorine-containing hydrophobic group Will be arranged on the surface layer of the film, thereby giving the entire agricultural film good self-cleaning performance.
  • the titanium dioxide includes nano-sized anatase TiO 2 .
  • TiO 2 has a photocatalytic effect. It can cause oxidation reactions of substances in both solid and liquid phases. It is the most important oxidant in photocatalytic oxidation. It can initiate a series of redox reactions and oxidize most organic pollutants. And some inorganic pollutants are finally decomposed into harmless substances such as CO 2 and H 2 O, thereby further playing a high self-cleaning role. Titanium dioxide also has excellent covering properties, so it should not be added too much in the transparent layer, otherwise it will reduce the total light transmittance.
  • the leveling agent may be a fluorocarbon modified polyacrylate leveling agent such as one or more of Efka FL 3770, Efka FL 3670, and Efka FL 3277 produced by BASF.
  • the anti-ultraviolet agent includes triazine-5, 2-(2-hydroxy-3,5-dibutyl tert-phenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-3,5 -Di-tert-amylphenyl)benzotriazole, 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole, 2,4-di-tert-butyl One or more of 6-(5-chlorobenzotriazol-2-yl)phenol and 2-hydroxy-4-n-octyloxybenzophenone.
  • the light stabilizer includes one or more of hindered amine light stabilizers, such as poly-1-(2-hydroxyethyl-2,2,6,6-tetramethyl-4-hydroxypiperidine).
  • Pyridine succinate bis(1,2,2,6,6-pentamethyl-4-piperidine) sebacate, 1-(methyl)-8-(1,2,2,6, 6-Pentamethyl-4-piperidine) sebacate, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate.
  • Anti-ultraviolet agent combined with light stabilizer, the anti-ultraviolet agent can absorb the ultraviolet rays irradiated on the film to inhibit the chemical decomposition reaction of ultraviolet rays and polymer compounds, and reduce the penetration of ultraviolet rays under the agricultural film.
  • the antioxidant includes one or more of hindered phenolic antioxidants and phosphite antioxidants, such as tetra[ ⁇ -(3,5-di-tert-butyl-4-hydroxybenzene) (Base) propionic acid) pentaerythritol ester, ⁇ -(3,5-di-tert-butyl-4-hydroxyphenyl) n-octadecyl propionate, tris(2,4-di-tert-butylphenyl) phosphorous acid Ester, 2,2'-thiobis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) ethyl propionate].
  • hindered phenolic antioxidants and phosphite antioxidants such as tetra[ ⁇ -(3,5-di-tert-butyl-4-hydroxybenzene) (Base) propionic acid) pentaerythritol ester, ⁇ -(3,5-
  • an antioxidant is added to the film of the present invention.
  • Antioxidants can effectively inhibit the oxidation and decomposition of the composite agricultural film by oxygen in the air, and improve the retention of physical properties of the composite agricultural film after being heated in aerobic air.
  • a preparation method of agricultural film includes the following steps:
  • S3 Weigh the surface layer raw materials and prepare the surface layer dispersion, coat the surface layer dispersion on the other side of the transparent PVC base film, and dry it to form an agricultural film.
  • the mixing of S1 is specifically: adding all the raw materials of the transparent PVC base film to a high-speed mixing machine and stirring the mixing at a speed of 500-600 rpm and a temperature of 110-120°C for 2-5 minutes, and then mixing the materials Add to the cold mixer and cool to 40-50°C before discharging.
  • S1 plasticizing extrusion is carried out in a twin-screw extruder, and the temperature of the feeding section, plasticizing section, exhaust section, extrusion section and die section of the twin-screw extruder are 120-150°C and 150-175 respectively. °C, 160-175°C, 165-175°C, 170-180°C; main engine speed is 30-40rpm.
  • S1 mastication is carried out in an open mill, including primary mastication and re-mastication.
  • the surface temperature of the roller during the initial mastication is 170-180°C, and the surface temperature of the roller during the re-plasticization is 175-185°C.
  • S1 calendering is carried out in a four-roll calender.
  • the linear speed of 1 roller is 42-48m/min, the speed ratio is 0.7-0.8, the surface temperature of the roller is 165-170°C;
  • the linear speed of 2 rollers is 50-55m /min, speed ratio 0.85-0.9, roller surface temperature 170-175°C; 3 roller linear speed 60m/min, speed ratio 1, roller surface temperature 170-175°C; 4 roller linear speed 50-55m/min, speed Ratio 0.85-0.9, roller surface temperature 165-170°C; traction cooling 1 roller linear speed 70-73m/min, speed ratio 1.2-1.25; traction cooling 2 roller linear speed 73-75m/min, speed ratio 1.25-1.3.
  • the preparation of the inner layer of S2 is specifically as follows: fully dissolving all the inner layer materials and stirring uniformly to obtain a transparent inner layer dispersion.
  • the coating of S2 adopts the high-pressure air atomization reciprocating spraying method, the spraying amount is 20-30g/m 2 , the drying temperature is 85-100°C, the film surface tension is 60-90N, and the drying molding time For 1-2min.
  • the preparation of the surface layer of S3 is as follows: firstly stir the other ingredients except hexamethylene diisocyanate thoroughly, then add the hexamethylene diisocyanate while stirring, and finally stir for 10-20min to obtain transparent Layer dispersion.
  • the coating of S3 adopts the high-pressure air atomized reciprocating spraying method, the spraying amount is 15-25g/m 2 , the drying temperature is 95-110°C, the film surface tension is 80-110N, and the drying molding time For 2-4min.
  • the present invention has the following advantages:
  • the polyvinyl chloride composite agricultural film of the present invention has high light transmittance and light scattering characteristics, and the haze can reach 50% (GB/T2410-2008) when the light transmittance is 86%, which can better use Crops can receive light in all directions and promote better photosynthesis of crops.
  • the polyvinyl chloride composite agricultural film of the present invention has a three-layer structure, the inner layer and the surface layer do not contain plasticizer components and can prevent the migration of the plasticizer of the transparent PVC base film layer, and the surface layer has self-cleaning characteristics.
  • the polyvinyl chloride composite agricultural film of the invention has good self-cleaning performance, is not easy to absorb dust, and has an increased service life.
  • the polyvinyl chloride composite agricultural film of the present invention has good anti-fogging dripping and heat preservation properties.
  • the polyvinyl chloride composite agricultural film of the present invention adopts multi-system components that have the ability to absorb and block ultraviolet rays, so that the agricultural film has a good ultraviolet blocking effect, and the ultraviolet blocking rate can reach 94%, which can effectively reduce various germs.
  • the reproduction and growth of insect pests are conducive to the growth of crops.
  • the polyvinyl chloride composite agricultural film of the present invention has excellent mechanical properties, heat resistance, and weather resistance, does not contain phthalic acid, has a fine and smooth hand feel, a refreshing and flat surface, and can be better used for planting fruits, Farmland cover for vegetable crops and crops such as cotton, corn, soybeans, and rice.
  • Figure 1 is a cross-sectional view of agricultural film
  • Figure 2 is a schematic diagram of the agricultural membrane structure
  • an agricultural film includes: a transparent PVC base film layer, the two sides of the base film layer are coated inner layer and surface layer respectively.
  • the agricultural film has high transparency, high light scattering, good self-cleaning, heat preservation, and anti-fogging performance.
  • PVC resin 100, calcium-zinc compound stabilizer: 3, triphenyl phosphite: 0.6, main plasticizer: 37, auxiliary plasticizer: 10, epoxy soybean oil: 3, ethylene-vinyl acetate copolymer: 3 , Vinyl chloride grafted chlorinated polyethylene copolymer: 3, fatty acid glyceride: 1.2, anti-ultraviolet agent: 0.7, antioxidant: 0.7, light stabilizer: 0.4, brightener: 0.02
  • the main plasticizer is trioctyl trimellitate; the auxiliary plasticizer is dioctyl adipate; the anti-ultraviolet agent is triazine-5; the antioxidant is tetra[ ⁇ -(3,5-di-tert-butyl) 4-hydroxyphenyl) propionic acid] pentaerythritol ester; the light stabilizer is poly 1-(2-hydroxyethyl-2,2,6,6-tetramethyl-4-hydroxypiperidine succinate; The brightener is 2.5-bis-(5-tert-butyl-2-benzoxazolyl)thiophene.
  • the surface temperature of the roller during the first plasticizing is 175°C
  • the surface temperature of the roller during the second plasticizing is 185°C
  • the film is calendered by a roll calender to obtain a transparent PVC base film with light scattering characteristics.
  • Four-roll calender 1 roller linear speed 45m/min, speed ratio 0.7, roller surface temperature 165°C; 2 roller linear speed 52m/min, speed ratio 0.85, roller surface temperature 170°C; 3 roller linear speed 60m/min, Speed ratio 1, roller surface temperature 175°C; 4 roller linear speed 54m/min, speed ratio 0.9, roller surface temperature 170°C; traction cooling 1 roller linear speed 70m/min, speed ratio 1.2; traction cooling 2 roller linear speed 74m/min, speed ratio 1.25.
  • Vinyl chloride-vinyl acetate copolymer resin solution 100, dripping agent: 3, antifogging agent: 3, heat insulating agent: 3.5, leveling agent: 0.5, anti-ultraviolet agent: 0.5, antioxidant: 0.5, light stabilizer : 0.3
  • the solid content of the vinyl chloride-vinyl acetate copolymer resin solution is 40%; the dripping agent is a mixture of fatty acid polyoxyethylene ether and sodium lauryl sulfonate with a mass ratio of 1:1; the antifogging agent is FS-60; leveling agent is Efka FL 3770; anti-ultraviolet agent is 2-hydroxy-4-n-octyloxybenzophenone; antioxidant is tetra[ ⁇ -(3,5-di-tert-butyl-4 -Hydroxyphenyl)propionic acid]pentaerythritol ester; the light stabilizer is bis(1,2,2,6,6-pentamethyl-4-piperidine) sebacate;
  • Vinyl chloride-vinyl acetate copolymer resin solution 40, acrylic modified alkyd resin solution: 40, fluorocarbon coating: 1.5, titanium dioxide: 0.1, leveling agent: 0.5, anti-ultraviolet agent: 0.5, antioxidant: 0.5, light Stabilizer: 0.3.
  • the solid content of the vinyl chloride-vinyl acetate copolymer resin solution is 40%; the solid content of the acrylic modified alkyd resin solution is 40%; the fluorocarbon coating is GK-570; the leveling agent is Efka FL3670; the anti-ultraviolet agent is 2- Hydroxy-4-n-octyloxy benzophenone; antioxidant is tetra[ ⁇ -(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] pentaerythritol ester; light stabilizer is sebacic acid Bis(1,2,2,6,6-pentamethyl-4-piperidine) ester;
  • Example 2 The only difference from Example 1 is that in the PVC transparent base film raw material of Example 2, the number of parts of ethylene-vinyl acetate copolymer is 2 parts, and the number of parts of vinyl chloride grafted chlorinated polyethylene copolymer is 2 parts.
  • Example 3 contains 4 parts of ethylene-vinyl acetate copolymer and 4 parts of vinyl chloride grafted chlorinated polyethylene copolymer.
  • Example 1 The only difference from Example 1 is that the amount of dripping agent in the inner layer raw material of Example 4 is 1.5 parts; the amount of antifogging agent is 1.5 parts.
  • Example 1 The only difference from Example 1 is that the amount of heat insulating agent in the inner layer raw material of Example 5 is 2 parts.
  • Example 1 The only difference from Example 1 is that the part of the fluorocarbon coating in the surface layer raw material of Example 6 is 1 part.
  • Example 7 The only difference from Example 1 is that the spraying amount of the S2 inner layer dispersion liquid on the PVC transparent base film in Example 7 is 20 g/m 2 .
  • Example 1 The only difference from Example 1 is that the spraying amount of the S3 surface layer dispersion liquid on the PVC transparent base film in Example 8 is 15 g/m 2 .
  • Example 9 The only difference from Example 1 is that the main plasticizer in the raw material of the PVC transparent base film in Example 9 is triglyceride trimellitate; the auxiliary plasticizer is dioctyl sebacate.
  • Example 1 The only difference from Example 1 is that in the PVC transparent base film raw material of Comparative Example 1, the part of the ethylene-vinyl acetate copolymer is 1 part, and the part of the vinyl chloride grafted chlorinated polyethylene copolymer is 1 part.
  • Example 1 The only difference from Example 1 is that the PVC transparent base film raw material of Comparative Example 2 does not contain ethylene-vinyl acetate copolymer and vinyl chloride grafted chlorinated polyethylene copolymer.
  • Example 1 The only difference from Example 1 is that the number of parts of ethylene-vinyl acetate copolymer in the raw material of the PVC transparent base film of Comparative Example 3 is 7 parts, and the number of parts of vinyl chloride grafted chlorinated polyethylene copolymer is 7 parts.
  • Example 1 The only difference from Example 1 is that in the raw material of the PVC transparent base film of Comparative Example 4, 3 parts of kaolin and 3 parts of talc were used to replace ethylene-vinyl acetate copolymer and vinyl chloride grafted chlorinated polyethylene copolymer.
  • Example 1 The only difference from Example 1 is that no dripping agent and antifogging agent are added to the inner layer raw material of Comparative Example 5.
  • Example 1 The only difference from Example 1 is that the amount of dripping agent in the inner layer raw material of Comparative Example 6 is 0.5 part; the amount of antifogging agent is 0.5 part.
  • Example 1 The only difference from Example 1 is that the inner layer raw material of Comparative Example 7 is not added with a heat insulating agent.
  • Example 1 The only difference from Example 1 is that the amount of heat insulating agent in the inner layer raw material of Comparative Example 8 is 1 part.
  • Example 1 The only difference from Example 1 is that the spray amount of the S2 inner layer dispersion liquid on the PVC transparent base film in Comparative Example 9 is 10 g/m 2 .
  • Example 10 The only difference from Example 1 is that in Comparative Example 10, the number of parts of the fluorocarbon coating (GK-570) in the surface layer raw material is 0.3 parts.
  • Example 1 The only difference from Example 1 is that the agricultural film of Comparative Example 11 has no surface layer.
  • Comparative Example 11 The only difference from Comparative Example 11 is that the plasticizer in the raw material of the PVC transparent base film of Comparative Example 12 is only 50 parts of dioctyl phthalate.
  • Example 1 The only difference from Example 1 is that the spray amount of the S2 inner layer dispersion on the PVC transparent base film in Comparative Example 13 is 40 g/m 2 .
  • Example 1 The only difference from Example 1 is that the spraying amount of the S3 outer layer dispersion liquid on the PVC transparent base film in Comparative Example 14 is 35 g/m 2 .
  • Detection method of anti-fog droplet performance build a 50cm ⁇ 50cm ⁇ 50cm shed with agricultural film at room temperature, place 2 liters of hot water at about 50°C in it, and observe the state of anti-fog droplet on the inner surface of the agricultural film after 10 minutes.
  • the polyvinyl chloride composite agricultural film prepared by the present invention has high light transmittance and light scattering properties, and its mechanical properties, anti-fogging dripping, heat preservation and self-cleaning properties are good.
  • the polyvinyl chloride composite agricultural film base film of the present invention uses organic EVA and CPE-g-VC with good visible light transmittance as the light scattering agent, which can ensure the high light transmittance of the agricultural film.
  • the film Under the premise of increasing the haze, the film has good light scattering characteristics.
  • the light passing through the agricultural film can be softly and uniformly scattered under the agricultural film cover, reducing direct glare, protecting crops from being burned, and making agricultural
  • the temperature and sunlight under the film cover are more evenly distributed, and the crop can receive light in all directions, which promotes better photosynthesis of the crop.
  • EVA and CPE-g-VC copolymers form a three-dimensional space with a continuous network.
  • the composite material system becomes a plastic alloy containing elastic particles.
  • the polyvinyl chloride composite agricultural film of the present invention adopts multi-system components (whitening agent, cesium tungstate and anti-ultraviolet absorber) that have ultraviolet absorbing and blocking effects, so that the agricultural film has a good ultraviolet blocking effect, and the ultraviolet blocking rate can reach 94%, cesium tungstate has certain ultraviolet absorption characteristics.
  • the ultraviolet blocking rate of the film is slightly reduced, but not obvious. This is because in the present invention, the main ultraviolet blocking effect is achieved by the anti-ultraviolet absorber.
  • the infrared absorption characteristics of cesium tungstate make the present invention have good infrared blocking rate and endow the final film with good thermal insulation performance. If the content of cesium tungstate in the transparent inner layer is reduced or the amount of spraying of the inner layer is reduced, the infrared of the film The barrier rate is reduced, see Examples 1, 5, and 7 and Comparative Examples 8, 9; In Comparative Example 7, which does not contain cesium tungstate in the inner layer, the infrared barrier rate of the film is significantly reduced, and the thermal insulation performance of the film is deteriorated.
  • the dripping agent and anti-fogging agent in the inner layer of the present invention can endow the film with good dripping and anti-fogging function. If the content of the dripping agent and anti-fogging agent in the transparent inner layer is reduced or the amount of spraying of the inner layer is reduced, the film’s The droplet anti-fog function is weakened, see Example 1 and Comparative Examples 5, 6, 9
  • the PVC base film of the present invention uses trimellitate plasticizers with low volatility, low migration, good extraction resistance and durability as the main plasticizer, and when used with epoxy soybean oil, it can reduce the plasticizer
  • trimellitate plasticizers with low volatility, low migration, good extraction resistance and durability as the main plasticizer, and when used with epoxy soybean oil, it can reduce the plasticizer
  • the self-cleaning performance of the film will decrease, see Comparative Examples 10 and 11; if traditional phthalic acid is used A type of plasticizer, instead of the plasticizer used in the present invention, the self-cleaning performance of the obtained film becomes worse.
  • the coating amount of the surface layer or the inner layer is increased, the transparency of the film will be reduced, the haze will increase, and the appearance and softness of the film will also be affected. See Comparative Examples 13 and 14, where the comparative example 13 has a partial feel. Hard, the outer surface of the film of Comparative Example 14 has poor flatness and has a hard hand feeling.

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Abstract

一种聚氯乙烯复合农用膜及其制备方法，该农用膜包括：PVC透明基膜层，所述基膜层两侧分别为涂布内层和面层。该农用膜结构组成简单，其中PVC透明基膜层具有光散射特性，涂布内层为具有消雾流滴和保温特性的透明内层；涂布面层为具有自洁特性的透明面层。该农用膜具有较高的透光性和光散射特性，良好的自洁、抗紫外、消雾流滴、保温隔热和力学性能，其耐热耐候性能优良，表面清爽平整，可以更好的应用于种植瓜果、蔬菜类作物和棉花、玉米、大豆、稻谷等农作物的农田覆盖。

Description

一种农用膜及其制备方法 技术领域
本发明涉及一种农用膜，具体涉及一种聚氯乙烯复合农用膜及其制备方法，属于农业技术领域。
背景技术
农用膜是每个国家农业产物不可缺少的一部分，已经成为继化肥和农药后的第三大农业生产原料。农用膜是应用于农业生产的塑料薄膜的总称，它对于农作物的保湿、保温、加速光合作用、调节光照、防草防虫等起到非常重要的作用，可以加快农作物生长、延长生长期、增产等。
目前常用的农用膜是用高分子复合材料采用压延或吹塑工艺制成的，主要有聚氯乙烯(PVC)膜、聚乙烯(PE)膜、乙烯-酯酸乙烯共聚物(EVA)膜、以及使用PE、EVA为主要材料的的多层(PO)膜。PVC农用膜以其机械强度好、弹性强、良好的透明度以及价格低廉等特性成为一种主要的农用膜。但是目前市面上传统PVC农用膜由于软质PVC中增塑剂的析出，会造成膜面易吸灰尘自洁性差，时间久后严重影响膜的透光性能。
农用膜在使用过程中，由于受外界气候和早晚温差变化的影响，可导致棚内产生雾气，薄膜附着了雾珠和水膜后，不仅会影响它的透光性能，阻碍光线进入大棚，面且由于水珠对太阳热量的吸收，会造成棚内地面温度的降低，影响农作物的光合作用，另外，薄膜上的水滴滴落在农作物上，还会引起农作物的病害。
针对该问题，可以在农用膜中引入具有消雾流滴功能的物质，如多元醇脂肪酸酯、烷基酚类、含氟或含硅类表面活性剂等，使棚内的雾气在薄膜表面铺展开来，形成连续的水沿大棚膜两侧流入地面，不形成水滴滴下。目前制备这种具有流滴功能的无滴膜主要有两种方法：一种是在制备农用膜的材料中加入消雾剂和流滴剂，然后挤出压延或者吹塑成膜。该技术方案操作简单，但由于这些表面活性剂物质与基体树脂(PE，EVA，PVC等)相容性差，其添加量受到限制，且大部分表面活性剂物质不能处于膜的表面，影响了其消雾剂流滴功能；另一种技术手段则是将消雾剂流滴剂制成涂液，然后将其涂覆于膜的表面，形成具有消雾剂流特性的农用膜。该技术方案对工艺要求较高，且由于消雾流滴类表面活性剂物质与PE，EVA，PVC等相容性差，尤其是普通PVC膜中含有大量增塑剂，长时间后，增塑剂的表面迁移使得这种表面处理得到的消雾流滴类表面活性剂物质容易与PVC层脱落，消雾流滴功能减弱。
随着农业技术要求的提高，农用膜不仅要求有高的透光率，还要求其具有一定的雾度以使得薄膜具有光散射特性。具有光散射特性的农用膜，一方面可以减少强光直射，保护农作物不被灼烧；另一方面，散射光也能照射到没有暴露于直射光线的被遮蔽的农作物部分，使农用膜覆盖下方的温度和阳光分布更均匀，作物能全方位接收光照，促进作物更好的光合作用，提高农作物质量和产量。塑料薄膜的透光率和雾度是一个相互矛盾的特性，雾度值的升高，则透光率会降低。
如公开号CN104441869A公开了光散射型农膜，其是在薄膜中添加一些无机 光散射颗粒：高岭土、硅藻土、滑石粉、水滑石、绢云母、硫酸钡等，但是，这些无机添加物不仅降低了薄膜的透明度，还会影响薄膜的力学性能。
发明内容
针对上述存在的问题，本发明提供一种具有高透明性、高光散射且自洁、保温、消雾流滴性能良好的农用膜及其制备方法。
为了实现上述目的，本发明采用以下技术方案：
一种农用膜，包括：PVC透明基膜层，所述基膜层两侧分别为涂布内层和面层。
本发明的农用膜结构组成简单，其中PVC透明基膜层具有光散射特性，涂布内层为具有消雾流滴和保温特性的透明内层；涂布面层为具有自洁特性的透明面层。
作为优选，所述农用膜的厚度为60-80μm。
作为优选，所述PVC透明基膜层，按重量份数计，包括如下组分：PVC树脂：90-110份、稳定剂：3-5份、增塑剂：40-55份、乙烯-醋酸乙烯共聚物：2-4份、氯乙烯接枝氯化聚乙烯共聚物：2-4份、润滑剂：1-1.5份、抗紫外线剂：0.4-1份、光稳定剂：0.2-0.5份、抗氧剂：0.4-1份、增白剂：0.01-0.05份。
进一步优选，所述PVC树脂的平均聚合度为1200-1500。
进一步优选，所述稳定剂包括2.5-4份主稳定剂、0.5-1份辅助定剂。
进一步优选，所述主稳定剂包括钙锌复合稳定剂，所述辅助定剂包括亚磷酸三苯脂。亚磷酸三苯脂与钙锌复合稳定剂配合使用时，能提高制品的耐热性、透明性、耐压析性、耐候性等实际使用性能。
进一步优选，所述增塑剂包括35-40份主塑剂、3-11份辅助增塑剂、2-4份环氧大豆油。
进一步优选，所述主塑剂包括偏苯三酸酯类增塑剂，所述辅助增塑剂包括脂肪酸酯类增塑剂。
进一步优选，所述主塑剂包括偏苯三酸三辛酯、偏苯三酸三(正辛正癸)酯、偏苯三酸三甘油酯中的一种或多种；所述辅助增塑剂包括己二酸二辛酯、葵二酸二辛酯、壬二酸二辛酯、己二酸二异癸酯中的一种或多种。
在PVC农用膜的原料中需要加入大量的增塑剂，而传统的增塑剂，如邻苯二甲酸酯类容易析出，长时间后，会使膜面易吸灰尘，自洁性差，严重影响膜透光性能。本发明采用挥发性低、迁移性小，耐抽出和耐久性良好的偏苯三酸酯类增塑剂作为主增塑剂。该类增塑剂兼具单体型增塑剂和聚合型增塑剂两者的优点，其与PVC的相容性和增塑效率又类似于邻苯二甲酸酯类。脂肪酸酯类增塑剂具有良好的耐寒性能，农用膜需要长时间昼夜放置在环境中，气候和温差变化强烈，本发明在PVC膜中加入具有耐寒特性的增塑剂，配合主增塑剂使用，使得该农用膜在在低温下也拥有良好的使用性能，延长了该农用膜的使用寿命。环氧大豆油与偏苯三酸酯类增塑剂并用，可以进一步避免后者向外迁移，另外环氧大豆油加入到PVC复合材料中，还能使PVC复合材料的热稳定性加强，起到辅助稳定剂 的作用。
进一步优选，所述乙烯-醋酸乙烯共聚物中，醋酸乙烯含量为25-40％；所述氯乙烯接枝氯化聚乙烯共聚物中，氯化聚乙烯的含量为50-65％，氯化聚乙烯中氯的含量为25-35％。醋酸乙烯含量越高，乙烯-醋酸乙烯共聚物的结晶度越低，透明度降低，醋酸乙烯减少则其与PVC相容性变差；而氯化聚乙烯中氯的含量为25-35％的时候，氯乙烯接枝氯化聚乙烯共聚物分子链成为柔性分子链，呈现出橡胶特性，从而起到增韧改性的作用。
为使光线透过农用膜后变为较为柔和的散射光而不是强烈的直线光，就需要增加农用膜的雾度，塑料薄膜的透光率和雾度是一个相互矛盾的特性，雾度值的升高，则透光率会降低。目前制备具有光散射特性薄膜的主要方法是在薄膜中添加一些无机光散射颗粒，如高岭土、硅藻土、滑石粉、水滑石、绢云母、硫酸钡等，这些无机添加物会降低薄膜的透明度，使得光线透过率降低，且对农用膜的机械性能也有影响。
本发明采用具有良好透光性能的有机树脂乙烯-醋酸乙烯共聚物(EVA)、氯乙烯接枝氯化聚乙烯共聚物(CPE-g-VC)作为光散射剂，在不降低光线总透过率的前提下实现光线的散射。EVA共聚物是由乙烯与醋酸乙烯通过共聚制得，由于在分子链中引入了醋酸乙烯单体，从而降低了结晶度，提高了柔韧性、抗冲击性，同时，由于其同时含有极性和非极性链段，使得其与各类极性和非极性高分子材料都具有一定的相容性。CPE-g-VC是以氯化聚乙烯(CPE)为主链与氯乙烯(VC)单体经接枝聚合反应制得的接枝共聚物树脂，其耐低温性、绝缘性、耐候性、抗燃烧性良好，与聚氯乙烯树脂有良好的相容性；而制备CPE-g-VC的CPE是高密度聚乙烯经氯化而制得的一种无规高分子氯化物，具有良好的透明性。EVA和CPE-g-VC含有与PVC具有一定相容性的极性基团，又含有与PVC相容性较差但具有透光性能的聚乙烯的基团，在与PVC分散共混后，这些与PVC相容性较差的聚乙烯基团或者整个EVA、CPE-g-VC共聚物能够均匀的分散在PVC连续相中，与PVC成为一种具有三维空间的连续网状“海岛结构”。由于EVA、CPE-g-VC与PVC对光线的折射率不同(PVC折射率约为1.539，本发明使用的EVA和CPE-g-VC的折射率较低，为1.45-1.49)，当光线通过连续PVC相进入到这些折射率不同的“海岛”的时候，光线就会改变原来的传播方向，出现折射现象，而当这些改变了传播方向的光线通过“海岛”进入PVC连续的时候，光线将再一次改变传播方向，出现折射现象，如此重复，这种微观不规则的三维连续光折射作用，使得所有透射光重复连续交叉，最后均匀的透过薄膜。更为重要的是，与采用无机光散射颗粒阻挡光线传播不同，本发明PVC连续相或者EVA和CPE-g-VC的“海岛”相，光线都能顺利透过，极大的保证了光线的总透过率。当光线通过具有折射作用的农用膜后，从微观角度看，光密度和温度分布是一致的，并且透过农用膜的光线柔和均一的散射在农用膜覆盖的下方，落到农作物的表面，一方面可以减少强光直射，保护农作物不被灼烧；另一方面，散射光也能照射到没有暴露于直射光线的被遮蔽的农作物部分，使农用膜覆盖下方的温度和阳光分布更均匀， 作物能全方位接收光照，促进作物更好的光合作用，提高农作物质量和产量。
另外由于在PVC中引入了EVA、CPE-g-VC共聚物，形成了一种具有连续网状的三维空间，复合材料体系成为一种含有弹性微粒子的塑料合金，这些结构极大的提高了PVC薄膜的力学性能。
进一步优选，所述增白剂包括苯并恶唑类荧光增白剂。荧光增白剂能吸收光线中不可见的紫外光，并转换为波长较长的蓝光或紫色的可见光，补偿PVC基质中的微黄色，互补形成白光，使PVC制品发出的白光增加，从而减弱PVC薄膜制品偏黄的缺点，使其感官更加透明亮白。而增白剂对紫外光的吸收，减少了紫外线对薄膜使用寿命的影响，并降低紫外光对农作物的影响，减少病虫害的发生。
进一步优选，所述润滑剂包括单脂肪酸甘油酯。润滑剂主要是用来改善聚氯乙烯的加工流动性能，降低聚氯乙烯与加工设备之间的摩擦力、防止聚氯乙烯粘接在金属加工设备上。而本发明中单脂肪酸甘油酯不仅起到加工润滑的作用，其表面活性还使其具有一定的流滴效果。
作为优选，所述涂布内层，按重量份数计，包括如下组分：氯乙烯-醋酸乙烯共聚树脂溶液：90-110份、流滴剂1.5-3.5份、消雾剂1.5-3.5份、隔热剂2-4份、流平剂0.3-0.7份、抗紫外线剂0.3-0.6份、抗氧剂0.3-0.6份、光稳定剂0.2-0.4份。
进一步优选，所述氯乙烯-醋酸乙烯共聚树脂溶液的固含量为30-50％。氯乙烯-醋酸乙烯共聚树脂(氯醋共聚树脂)是氯乙烯与醋酸乙烯单体进行共聚制得的聚合物，其与PVC相容性良好，含有的醋酸乙烯基团则与内层中其它添加剂具有良好的相容耦合作用。采用氯醋共聚树脂作为透明内层的基体树脂，其与PVC良好的相容性使得透明内层与PVC基膜层更加完美的融合为一体，解决了消雾流滴类表面活性剂物质涂液与PVC基膜相容性差，消雾流滴功效随时间逐渐减弱的问题，从而拥有消雾流滴功效的永久性。
进一步优选，所述氯乙烯-醋酸乙烯共聚树脂溶液中，醋酸乙烯含量为10-30％。
进一步优选，所述流滴剂包括脂肪酸聚氧乙烯醚、十二烷基硫酸钠、十二烷基磺酸钠、单脂肪酸甘油酯、辛基酚聚氧乙烯醚、山梨糖醇酐脂肪酸酯、椰子油酸二乙醇酰胺中的一种或多种。
在农业生产中，由于受外界气候和早晚温差变化的影响，农用膜内温度通常高于外界温度，薄膜表面的温度通常在露点以下，膜内水蒸气就会冷凝在薄膜表面上形成小的水滴，由于高分子聚合物疏水性较强，水滴在薄膜的表面无法展开，会直接阻碍阳光的直射，妨碍作物的光合作用。同时，水滴还会由于自重滴落在农作物上，容易使作物发生病虫害、枯烂等现象。本发明所使用的流滴剂是非离子性表面活性剂，具有亲水基和疏水基，在薄膜表面固化排列成型的时候，疏水基朝内，亲水基朝外，提高了薄膜的表面能；同时，在与水滴相溶后，亲水基朝水内侧，疏水基朝外排列，能够降低水的表面张力。当水的表面张力降低到等于或小于薄膜的临界表面张力时，水能够在薄膜表面展开，形成水膜而不是水滴， 从而解决了流滴的问题。
进一步优选，所述消雾剂为含氟类表面活性剂，可以是杜邦公司生产的
Figure PCTCN2019119600-appb-000001
FS-65、
Figure PCTCN2019119600-appb-000002
FS-60、
Figure PCTCN2019119600-appb-000003
FS-63、
Figure PCTCN2019119600-appb-000004
FS-22、
Figure PCTCN2019119600-appb-000005
FS-3100中的一种或多种。
在早春和晚秋季节，特别是早晨和傍晚，农用膜内外的温度变化较大，加上湿度较大，温度的降低会使棚内的水蒸气达到过饱和从而冷凝行成细小的雾滴，当形成雾滴的速度大于消雾的速度时，雾就会弥漫开来，会严重阻碍阳光的透过。流滴剂虽然能够将水滴展平为水膜，但其溶于水层后会在水膜中形成紧密排列，疏水基团朝外，阻碍了水膜对雾气的吸收。因此，流滴剂只具有流滴功能，并不能有效消除雾气，这时就需要消雾剂。本发明使用表面活性极强的含氟类表面活性剂做为消雾剂，能够进一步降低水的表面张力，使得水膜展开成更薄的水层，更快地流到地面，从而提高水层吸收雾滴的效率。同时，由于含氟类消雾剂憎水憎油的特性，其空间占位效应打乱了流滴剂在水膜-空气界面上的有序排列，从而增加了雾气粘附到水膜的概率，提高了消雾能力。由于棚膜内表面附近的雾气能够迅速被捕获形成较薄水膜并顺着薄膜表面流下，当棚膜附近的水蒸气由过饱和变成不饱和时，雾气便随之消失。同时由于平衡被打破，膜内的雾气会扩散迁移到膜附近，继续被捕获粘附，因此即使膜内温度降低，膜内水蒸气也能处于不饱和状态，从而达到消除雾气的效果。
进一步优选，所述隔热剂包括纳米级钨酸铯。
农用膜内白天和晚间的温差变化大，夏天白天的高温会使得作物生长缓慢，为此本发明在透明内层中添加了具有红外吸收隔热特性的纳米钨酸铯隔热剂。纳米钨酸铯在近红外区域800-1100nm具有极强的吸收特性，能抑制农用膜下方植物所放出的红外热量，减少晚间农用膜下方热量的损失，具有隔热保温效应，加快农作物的生长；同时也减弱了白天正午阳光的高温对作物生长的影响。另外，钨酸铯在可见光区域具有较强透过特性，不影响阳光的透过性，并且钨酸铯对200-380nm的紫外光也具有较强的屏蔽特性，不仅对薄膜抗紫外老化有益，还能进一步降低进入农用膜下方的紫外线量，减少病虫害的发生。
作为优选，所述涂布面层，按重量份数计，包括如下组分：氯乙烯-醋酸乙烯共聚树脂溶液：30-50份、丙烯酸改性醇酸树脂溶液30-50份、氟碳涂料1-2份、六亚甲基二异氰酸酯0.1-0.2份，二氧化钛0.05-0.15份、流平剂0.3-0.6份、抗紫外线剂0.4-0.7份、抗氧剂0.4-0.7份、光稳定剂0.2-0.5份。
丙烯酸改性醇酸树脂，既保留了醇酸树脂丰满度好、容易施工等特点，又继承了热塑性丙烯酸酯树脂快干、高透明、优良的保色性和户外耐候性的特点，增强了耐候性能。氯乙烯-醋酸乙烯共聚树脂与PVC基膜优异的相容性，使其在面层中起到增加附着力的作用，让自洁面层能更好的与PVC基膜溶于一体。抗紫外线剂和抗氧剂的加入能减缓高分子塑料的分解老化，延长其使用寿命。
进一步优选，所述丙烯酸改性醇酸树脂溶液的固含量为30-50％。
进一步优选，所述氯乙烯-醋酸乙烯共聚树脂中，醋酸乙烯含量为10-30％； 所述丙烯酸改性醇酸树脂中，丙烯酸组分含量为20-60％。
进一步优选，所述氟碳涂料可以是大金公司的ZEFFLE系列氟碳涂料，如GK-570和GK-510。本发明所用氟碳涂料是一种四氟乙烯与乙烯基单体的共聚物，在六亚甲基二异氰酸酯固化剂的作用下，能快速固化成膜，成膜的时候其含氟疏水基团将会向膜的表面层排列，从而赋予整个农用膜良好的自洁性能。
进一步优选，所述二氧化钛包括纳米级锐钛晶型的TiO 2。
TiO 2具有光催化效应，无论在固相还是在液相都能引起物质的氧化反应，是光催化氧化中最主要的氧化剂，可以引发一系列的氧化还原反应，能氧化大多数的有机污染物及部分无机污染物，将其最终分解为CO 2和H 2O等无害物质，从而进一步起到高自洁的作用。二氧化钛也具有优异的遮盖性能，所以在本透明层中其添加量不宜过多，否则会减少光线的总透过率。
进一步优选，所述流平剂可以是氟碳改性聚丙烯酸酯类流平剂如巴斯夫生产的Efka FL 3770、Efka FL 3670、Efka FL 3277中的一种或多种。
进一步优选，所述抗紫外线剂包括三嗪-5、2-(2-羟基-3,5-二丁叔基苯基)-5-氯代苯并三唑、2-(2-羟基-3，5-二叔戊基苯基)苯并三唑、2-(2-羟基-3-特丁基-5-甲基苯基)-5-氯苯并三唑、2,4-二-叔丁基-6-(5-氯代苯并三唑-2-基)苯酚、2-羟基-4-正辛氧基二苯甲酮中的一种或多种。
进一步优选，所述光稳定剂包括受阻胺类光稳定剂中的一种或多种，如聚1-(2-羟乙基-2,2,6,6-四甲基-4-羟基哌啶丁二酸酯、癸二酸双(1,2,2,6,6-五甲基-4-哌啶)酯、1-(甲基)-8-(1,2,2,6,6-五甲基-4-哌啶)癸二酸酯、双(2,2,6,6－四甲基－4－哌啶基)癸二酸酯。
塑料制品的老化分解严重影响其使用寿命，太阳光中的紫外线是引起塑料制品分解的主要原因。另外长时间的紫外线的照射(尤其是350-380nm的紫外线)不仅使作物的枝杆加速老化抑制织物的生长，而且会使土壤中的各种病菌和虫害加速繁殖生长，使作物出现病果、裂果减少作物的产量。虽然在本发明的农膜中含有对紫外线具有吸收特性的荧光增白剂和钨酸铯，但依然不够，为进一步增加薄膜对紫外线的阻隔功效，本发明农膜各层中都加有抗紫外线剂，配合光稳定剂，抗紫外线剂能将照射至薄膜上的紫外线吸收从而抑制紫外线与高分子化合物的化学分解反应，减少紫外线进入到农膜下方。
进一步优选，所述抗氧剂包括受阻酚类抗氧剂、亚磷酸酯类抗氧剂中的一种或多种，如四[β-(3，5-二叔丁基-4-羟基苯基)丙酸]季戊四醇酯、β-(3,5-二叔丁基-4-羟基苯基)丙酸正十八碳醇酯、三(2,4-二叔丁基苯基)亚磷酸酯、2,2'-硫代双[3-(3,5-二叔丁基-4-羟基苯基)丙酸乙酯]。为进一步增加PVC薄膜的使用寿命，本发明薄膜中添加了抗氧剂。抗氧剂能有效抑制空气中的氧气对复合农用膜的氧化分解作用，改善复合农用膜在有氧空气中加热后物理性能的保留。
一种农用膜的制备方法，包括如下步骤：
S1：称取PVC透明基膜层原料，通过混料、塑化挤出、塑炼、压延后制成PVC透明基膜；
S2：称取内层原料并制成内层分散液，将内层分散液涂布于PVC透明基膜一侧，烘干成型；
S3：称取面层原料并制成面层分散液，将面层分散液涂布于PVC透明基膜另一侧，烘干成型得农用膜。
作为优选，S1所述混料具体为：将所有PVC透明基膜层原料加入到高速混料机并在500-600rpm的转速、110-120℃的温度下搅拌混料2-5min，然后将物料加入至冷混机冷却到40-50℃后出料。
作为优选，S1塑化挤出在双螺杆挤出机进行，双螺杆挤出机加料段、塑化段、排气段、挤出段、模口段温度分别为120-150℃、150-175℃、160-175℃、165-175℃、170-180℃；主机转速为30-40rpm。
作为优选，S1塑炼在开炼机中进行，包括初次塑炼和再次塑炼，初次塑炼时辊筒表面温度为170-180℃，再次塑炼时辊筒表面温度为175-185℃。
作为优选，S1压延在四辊压延机中进行，压延成膜时，1辊线速度42-48m/min，速比0.7-0.8，辊筒表面温度165-170℃；2辊线速度50-55m/min，速比0.85-0.9，辊筒表面温度170-175℃；3辊线速度60m/min，速比1，辊筒表面温度170-175℃；4辊线速度50-55m/min，速比0.85-0.9，辊筒表面温度165-170℃；牵引冷却1辊线速度70-73m/min，速比1.2-1.25；牵引冷却2辊线速度73-75m/min，速比1.25-1.3。
作为优选，S2所述内层制备具体为：将所有内层原料充分溶解搅拌均匀，得透明内层分散液。
作为优选，S2所述涂布采用高压空气雾化往复式喷涂法，喷涂量为20-30g/m 2，烘干成型的温度为85-100℃，膜面张力60-90N，烘干成型时间为1-2min。
作为优选，S3所述面层制备具体为：首先将除六亚甲基二异氰酸酯外的其他成分充分搅拌均匀，然后边搅拌边加入六亚甲基二异氰酸酯，最后搅拌10-20min，得透明外层分散液。
作为优选，S3所述涂布采用高压空气雾化往复式喷涂法，喷涂量为15-25g/m 2，烘干成型的温度为95-110℃，膜面张力80-110N，烘干成型时间为2-4min。
与其他材料相比，本发明具有如下优点：
(1)本发明的聚氯乙烯复合农用膜具有较高的透光性和光散射特性，在透光率为86％时雾度可达到50％(GB/T2410-2008)，能更好的使作物能全方位接收光照，促进作物更好的光合作用。
(2)本发明的聚氯乙烯复合农用膜具有三层结构，内层与面层不含增塑剂成份并能阻止PVC透明基膜层增塑剂的外迁，面层具有自洁特性，使得本发明聚氯乙烯复合农用膜自洁性能良好，不易吸灰尘，使用寿命增加。
(3)本发明的聚氯乙烯复合农用膜具有良好的消雾流滴和保温特性。
(4)本发明的聚氯乙烯复合农用膜采用了对紫外线具有吸收阻隔功效的的 多体系成份，使得农用膜具有良好的紫外线阻隔作用，紫外线阻隔率可达94％，能有效减少各种病菌和虫害的繁殖生长，有利于作物的生长。
(5)本发明的聚氯乙烯复合农用膜力学性能、耐热性能、耐候性能优良，不含邻苯二甲酸，其手感细致爽滑、表面清爽平整，可以更好的应用于种植瓜果、蔬菜类作物和棉花、玉米、大豆、稻谷等农作物的农田覆盖。
附图说明
图1为农用膜剖视图；
图2为农用膜结构示意图；
图中，1、面层；2、PVC透明基膜层；3、内层。
具体实施方式
以下是本发明的具体实施例，对本发明的技术方案作进一步的描述，但本发明并不限于这些实施例。
如图1-2所示，一种农用膜，包括：PVC透明基膜层，所述基膜层两侧分别为涂布内层和面层。农用膜具有高透明性、高光散射且自洁、保温、消雾流滴性能良好。
实施例1
S1:制备PVC透明基膜
先称取如下重量份数原料：
PVC树脂：100，钙锌复合稳定剂：3，亚磷酸三苯脂：0.6，主增塑剂：37，辅助增塑剂：10，环氧大豆油：3，乙烯-醋酸乙烯共聚物：3，氯乙烯接枝氯化聚乙烯共聚物：3，单脂肪酸甘油酯：1.2，抗紫外线剂：0.7，抗氧剂：0.7，光稳定剂：0.4，增白剂：0.02
主增塑剂为偏苯三酸三辛酯；辅助增塑剂为己二酸二辛酯；抗紫外线剂为三嗪-5；抗氧剂为四[β-(3，5-二叔丁基-4-羟基苯基)丙酸]季戊四醇酯；光稳定剂为聚1-(2-羟乙基-2,2,6,6-四甲基-4-羟基哌啶丁二酸酯；增白剂为2.5-双-(5-叔丁基-2-苯并恶唑基)噻吩。
将配料加入到高速混料机并在550rpm的转速、115℃的温度下搅拌混料4分钟，然后将物料加入至冷混机冷却到45℃后出料；然后将混料好的配料采用双螺杆挤出机挤出造粒，双螺杆挤出机加料段、塑化段、排气段、挤出段、模口段温度分别为130℃、165℃、165℃、170℃、175℃，主机转速为35rpm；之后将所得到的粒料加入到开炼机塑炼，初次塑炼时辊筒表面温度为175℃，再次塑炼时辊筒表面温度为185℃；之后将物料加入到四辊压延机压延成膜，得到具有光散射特性的PVC透明基膜。四辊压延机1辊线速度45m/min，速比0.7，辊筒表面温度165℃；2辊线速度52m/min，速比0.85，辊筒表面温度170℃；3辊线速度60m/min，速比1，辊筒表面温度175℃；4辊线速度54m/min，速比0.9，辊筒表面温度170℃；牵引冷却1辊线速度70m/min，速比1.2；牵引冷却2辊线速度74m/min，速比1.25。
S2：称取如下重量份数原料：
氯乙烯-醋酸乙烯共聚树脂溶液：100，流滴剂：3，消雾剂：3，隔热剂：3.5，流平剂：0.5，抗紫外线剂：0.5，抗氧剂：0.5，光稳定剂：0.3
其中氯乙烯-醋酸乙烯共聚树脂溶液固含量为40％；流滴剂为质量比为1：1的脂肪酸聚氧乙烯醚与十二烷基磺酸钠的混合物；消雾剂为
Figure PCTCN2019119600-appb-000006
FS-60；流平剂为Efka FL 3770；抗紫外线剂为2-羟基-4-正辛氧基二苯甲酮；抗氧剂为四[β-(3，5-二叔丁基-4-羟基苯基)丙酸]季戊四醇酯；光稳定剂为癸二酸双(1,2,2,6,6-五甲基-4-哌啶)酯；
将所有配料充分溶解搅拌均匀，得透明内层分散液；然后采用高压空气雾化往复式喷涂的方法，将分散液涂布于PVC透明基膜一侧，喷涂量为28g/m 2，在膜面张力80N、温度95℃的条件下烘干成型，时间2min。
S3：称取如下重量份数原料：
氯乙烯-醋酸乙烯共聚树脂溶液：40，丙烯酸改性醇酸树脂溶液：40，氟碳涂料：1.5，二氧化钛：0.1，流平剂：0.5，抗紫外线剂：0.5，抗氧剂：0.5，光稳定剂：0.3。
其中氯乙烯-醋酸乙烯共聚树脂溶液固含量为40％；丙烯酸改性醇酸树脂溶液固含量为40％；氟碳涂料为GK-570；流平剂为Efka FL 3670；抗紫外线剂为2-羟基-4-正辛氧基二苯甲酮；抗氧剂为四[β-(3，5-二叔丁基-4-羟基苯基)丙酸]季戊四醇酯；光稳定剂为癸二酸双(1,2,2,6,6-五甲基-4-哌啶)酯；
将上述配料充分溶解搅拌均匀，然后边搅拌边加入0.15份六亚甲基二异氰酸酯，最后搅拌10min，得透明面层分散液；然后采用高压空气雾化往复式喷涂的方法，将分散液涂布于PVC透明基膜另一侧，喷涂量为22g/m 2，在膜面张力90N、温度102℃的条件下烘干成型，时间3.5min，得到聚氯乙烯复合农用膜。
实施例2
与实施例1的区别仅在于，实施例2的PVC透明基膜原料中乙烯-醋酸乙烯共聚物的份数为2份、氯乙烯接枝氯化聚乙烯共聚物的份数为2份。
实施例3
与实施例1的区别仅在于，实施例3的PVC透明基膜原料中乙烯-醋酸乙烯共聚物的份数为4份、氯乙烯接枝氯化聚乙烯共聚物的份数为4份。
实施例4
与实施例1的区别仅在于，实施例4的内层原料中流滴剂份数为1.5份；消雾剂份数为1.5份。
实施例5
与实施例1的区别仅在于，实施例5的内层原料中隔热剂的份数为2份。
实施例6
与实施例1的区别仅在于，实施例6的面层原料中氟碳涂料的份数为1份。
实施例7
与实施例1的区别仅在于，实施例7中S2内层分散液在PVC透明基膜上的喷涂量为20g/m 2。
实施例8
与实施例1的区别仅在于，实施例8中S3面层分散液在PVC透明基膜上的喷涂量为15g/m 2。
实施例9
与实施例1的区别仅在于，实施例9中PVC透明基膜原料中主增塑剂为偏苯三酸三甘油酯；辅助增塑剂为葵二酸二辛酯。
对比例1
与实施例1的区别仅在于，对比例1的PVC透明基膜原料中乙烯-醋酸乙烯共聚物的份数为1份、氯乙烯接枝氯化聚乙烯共聚物的份数为1份。
对比例2
与实施例1的区别仅在于，对比例2的PVC透明基膜原料中不含乙烯-醋酸乙烯共聚物和氯乙烯接枝氯化聚乙烯共聚物。
对比例3
与实施例1的区别仅在于，对比例3的PVC透明基膜原料中乙烯-醋酸乙烯共聚物的份数为7份、氯乙烯接枝氯化聚乙烯共聚物的份数为7份。
对比例4
与实施例1的区别仅在于，对比例4的PVC透明基膜原料中以高岭土3份、滑石粉3份替换乙烯-醋酸乙烯共聚物、氯乙烯接枝氯化聚乙烯共聚物。
对比例5
与实施例1的区别仅在于，对比例5的内层原料中不添加流滴剂和消雾剂。
对比例6
与实施例1的区别仅在于，对比例6的内层原料中流滴剂份数为0.5份；消雾剂份数为0.5份。
对比例7
与实施例1的区别仅在于，对比例7的内层原料中不添加隔热剂。
对比例8
与实施例1的区别仅在于，对比例8的内层原料中隔热剂的份数为1份。
对比例9
与实施例1的区别仅在于，对比例9中S2内层分散液在PVC透明基膜上的喷涂量为10g/m 2。
对比例10
与实施例1的区别仅在于，对比例10中面层原料中氟碳涂料(GK-570)的份数为0.3份。
对比例11
与实施例1的区别仅在于，对比例11农用膜无面层。
对比例12
与对比例11的区别仅在于，对比例12的PVC透明基膜原料中增塑剂仅为邻苯二甲酸二辛酯50份。
对比例13
与实施例1的区别仅在于，对比例13中S2内层分散液在PVC透明基膜上的喷涂量为40g/m 2。
对比例14
与实施例1的区别仅在于，对比例14中S3外层分散液在PVC透明基膜上的喷涂量为35g/m 2。
表1：实施例1-9及对比例1-14中农用膜的理化性能
Figure PCTCN2019119600-appb-000007
Figure PCTCN2019119600-appb-000008
注一：透光率、雾度测试标准：GB/T2410-2008；拉伸强度测试标准：GB/T13022-1991；直角撕裂强度测试标准：QB/T1130-1991；红外线阻隔率和紫外线阻隔率采用深圳林上科技有限公司的LS183光学透过率测量仪测量，测试标准：JJF 1225-2009。
注二：消雾流滴性能检测方法：在室温下用农用膜搭建一个50cm×50cm×50cm棚，里面放置50℃左右的热水2升，10min后观察农用膜内表面消雾流滴状态。
注三：表面自洁性能检测方法：将农用膜在35℃的条件下放置30天后，取50×50cm大小，让其面层表面与特制粉尘(由高岭石，普通硅酸盐水泥粉，碳黑，碳酸钙，氢氧化镁组成)接触，观察农用膜面层表面吸灰情况。
注四：○……好；△……一般；×……差。
从表一的实施例可见，本发明所制备的聚氯乙烯复合农用膜具有较高的透光性和光散射特性，其力学性能、消雾流滴、保温和自洁特性良好。
从实施例和对比例可以看出，本发明聚氯乙烯复合农用膜基膜中采用具有良好可见光透过性的有机EVA、CPE-g-VC作为光散射剂，在保证农用膜高透光率的前提下提高了雾度，使得薄膜具有良好的光散射特性，透过农用膜的光线能柔和均一的散射在农膜覆盖的下方，减少强光直射，保护农作物不被灼烧，并使农膜覆盖下方的温度和阳光分布更均匀，作物能全方位接收光照，促进作物更好的光合作用。在EVA、CPE-g-VC添加量变少或者不添加的情况下，农用膜的透明度有所增加，但雾度降低，光散射特性减弱，见施例1、2、3和对比例1、2。若 EVA、CPE-g-VC添加量过多，将使薄膜的透光率明显下降，雾度增加，见对比例3。另外EVA、CPE-g-VC共聚物，形成了一种具有连续网状的三维空间，复合材料体系成为一种含有弹性微粒子的塑料合金，这些结构极大的提高了PVC薄膜的力学性能，在一定范围的添加量内，随着EVA、CPE-g-VC共聚物量的增多，薄膜的拉伸和直角撕裂强度有所提高，见施例1、2、3和对比例1、2，但若EVA、CPE-g-VC添加量过多，不仅使薄膜的透光率明显下降，雾度增加，还会使薄膜的力学性能降低，见对比例3。若用具有光散射特性的高岭土和滑石粉等质量代替EVA和CPE-g-VC，所得到的薄膜雾度增加明显，但是透光率明显比EVA和CPE-g-VC的差，且高岭土和滑石粉无机添加成份对薄膜的力学性能影响较大，见施例1和对比例4。
本发明的聚氯乙烯复合农用膜采用了对紫外线具有吸收阻隔功效的多体系成份(增白剂、钨酸铯和抗紫外线吸收剂)使得农用膜具有良好的紫外线阻隔作用，紫外线阻隔率可达94％，钨酸铯具有一定的紫外线吸收特性，在不添加钨酸铯的对比例7或者钨酸铯的量减少的对比例8情况下，薄膜的紫外线阻隔率略有降低，但不明显，这是因为本发明中，主要的紫外线阻隔作用是由抗紫外线吸收剂来实现的。
钨酸铯的红外吸收特性使得本发明具有良好的红外线阻隔率，赋予最终薄膜良好的保温隔热性能，若透明内层中钨酸铯含量减少或者内层喷涂量减少的情况下，薄膜的红外线阻隔率降低，见施例1、5、7和对比例8、9；在内层不含钨酸铯的对比例7中，薄膜的红外线阻隔率明显降低，薄膜的保温隔热性能变差。
本发明内层中的流滴剂和消雾剂能赋予薄膜良好的流滴消雾功能，若透明内层中流滴剂和消雾剂的含量减少或者内层喷涂量减少的情况下，薄膜的流滴消雾功能减弱，见施例1和对比例5、6、9
本发明PVC基膜中采用挥发性低、迁移性小，耐抽出和耐久性良好的偏苯三酸酯类增塑剂作为主增塑剂，配合环氧大豆油使用，能减少增塑剂的外析特性，再加上农膜表面含有与PVC基膜融为一体的透明自洁面层，使得薄膜具有良好的抗增塑剂析出和自洁性能。若薄膜表面不涂布该透明自洁面层，或者面层中含有自洁特性的氟碳成份减少则薄膜的自洁性能有所下降，见对比例10、11；若使用传统的邻苯二甲酸类增塑剂，代替本发明用增塑剂，则所得薄膜的自洁性能变差，见对比例11、12。
若面层或内层的涂布量加大，则会使膜的透明度降低，雾度增加，并且还会影响膜的外观和柔软性能，见对比例13、14，其中对比例13膜手感偏硬，对比例14膜外表面平整度欠佳，手感偏硬。
尽管对本发明已作出了详细的说明并引证了一些具体实施例，但是对本领域熟练技术人员来说，只要不离开本发明的精神和范围可作各种变化或修正是显然的。

Claims (13)

  1. 一种农用膜，其特征在于，包括：PVC透明基膜层，所述基膜层两侧分别为涂布内层和面层。
  2. 根据权利要求1所述的一种农用膜，其特征在于，所述PVC透明基膜层，按重量份数计，包括如下组分：PVC树脂：90-110份、稳定剂：3-5份、增塑剂：40-55份、乙烯-醋酸乙烯共聚物：2-4份、氯乙烯接枝氯化聚乙烯共聚物：2-4份、润滑剂：1-1.5份、抗紫外线剂：0.4-1份、光稳定剂：0.2-0.5份、抗氧剂：0.4-1份、增白剂：0.01-0.05份。
  3. 根据权利要求2所述的一种农用膜，其特征在于，所述稳定剂包括2.5-4份主稳定剂、0.5-1份辅助定剂，所述主稳定剂包括钙锌复合稳定剂，所述辅助定剂包括亚磷酸三苯脂。
  4. 根据权利要求2所述的一种农用膜，其特征在于，所述增塑剂包括35-40份主塑剂、3-11份辅助增塑剂、2-4份环氧大豆油，所述主塑剂包括偏苯三酸酯类增塑剂，所述辅助增塑剂包括脂肪酸酯类增塑剂。
  5. 根据权利要求2所述的一种农用膜，其特征在于，所述乙烯-醋酸乙烯共聚物中，醋酸乙烯含量为25-40％；所述氯乙烯接枝氯化聚乙烯共聚物中，氯化聚乙烯的含量为50-65％，氯化聚乙烯中氯的含量为25-35％。
  6. 根据权利要求1所述的一种农用膜，其特征在于，所述涂布内层，按重量份数计，包括如下组分：氯乙烯-醋酸乙烯共聚树脂溶液：90-110份、流滴剂1.5-3.5份、消雾剂1.5-3.5份、隔热剂2-4份、流平剂0.3-0.7份、抗紫外线剂0.3-0.6份、抗氧剂0.3-0.6份、光稳定剂0.2-0.4份。
  7. 根据权利要求6所述的一种农用膜，其特征在于，所述流滴剂包括脂肪酸聚氧乙烯醚、十二烷基硫酸钠、十二烷基磺酸钠、单脂肪酸甘油酯、辛基酚聚氧乙烯醚、山梨糖醇酐脂肪酸酯、椰子油酸二乙醇酰胺中的一种或多种；所述消雾剂包括含氟类表面活性剂；所述隔热剂包括纳米级钨酸铯。
  8. 根据权利要求1所述的一种农用膜，其特征在于，所述面 层，按重量份数计，包括如下组分：氯乙烯-醋酸乙烯共聚树脂溶液：30-50份、丙烯酸改性醇酸树脂溶液30-50份、氟碳涂料1-2份、六亚甲基二异氰酸酯0.1-0.2份，二氧化钛0.05-0.15份、流平剂0.3-0.6份、抗紫外线剂0.4-0.7份、抗氧剂0.4-0.7份、光稳定剂0.2-0.5份。
  9. 根据权利要求6所述的一种农用膜，其特征在于，所述氯乙烯-醋酸乙烯共聚树脂中，醋酸乙烯含量为10-30％；所述丙烯酸改性醇酸树脂中，丙烯酸组分含量为20-60％；所述二氧化钛包括纳米级锐钛晶型的TiO 2。
  10. 根据权利要求8所述的一种农用膜，其特征在于，所述氯乙烯-醋酸乙烯共聚树脂中，醋酸乙烯含量为10-30％；所述丙烯酸改性醇酸树脂中，丙烯酸组分含量为20-60％；所述二氧化钛包括纳米级锐钛晶型的TiO 2。
  11. 一种如权利要求1所述的一种农用膜的制备方法，其特征在于，包括如下步骤：
    S1：称取PVC透明基膜层原料，通过压延法制成PVC透明基膜；
    S2：称取内层原料并制成内层分散液，将内层分散液涂布于PVC透明基膜一侧，烘干成型；
    S3：称取面层原料并制成面层分散液，将面层分散液涂布于PVC透明基膜另一侧，烘干成型得农用膜。
  12. 根据权利要求11所述的一种农用膜的制备方法，其特征在于，S2所述涂布采用高压空气雾化往复式喷涂法，喷涂量为20-30g/m 2，烘干成型的温度为85-100℃，膜面张力60-90N，烘干成型时间为1-2min。
  13. 根据权利要求11所述的一种农用膜的制备方法，其特征在于，S3所述涂布采用高压空气雾化往复式喷涂法，喷涂量为15-25g/m 2，烘干成型的温度为95-110℃，膜面张力80-110N，烘干成型时间为2-4min。
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