A linear low-density polyethylene composition for weather-resistant mulch film, its preparation method and application

Abstract

This invention provides a linear low-density polyethylene composition for weather-resistant mulch film, its preparation method, and its application. The composition contains LLDPE resin, an inorganic particle / rubber particle composite, and optional additives. The inorganic particle / rubber particle composite contains inorganic particles and rubber particles coated on the surface of the inorganic particles. The inorganic particles have a mesh size of 800–4000 mesh, preferably 1500–3500 mesh, and more preferably 1500–3000 mesh. The rubber particles are cross-linked rubber particles. This invention solves the problem of uneven winding during mulch film production (especially under high blow-up ratio conditions) caused by existing raw materials. It improves the extrusion blow molding process, resulting in more uniform film winding. This not only reduces waste film generation and improves production efficiency but also eliminates the need for LLDPE, LDPE, or HDPE resin compounding, simplifying the process and reducing production costs.

Description

Technical Field

[0001] This invention relates to a polyolefin composition, and more specifically to a linear low-density polyethylene composition for weather-resistant mulch film, its preparation method, and its application. Background Technology

[0002] Agricultural mulch film (referred to as mulch film) has functions such as moisture retention, temperature increase, and water conservation, making significant contributions to increased agricultural production and farmers' income. It has become an indispensable production material for agriculture. my country is the world's largest producer and distributor of agricultural mulch film, accounting for 75% of global production. Data from the National Bureau of Statistics shows that in 2015, my country's mulch film coverage area reached 275 million mu (approximately 18.7 million hectares), with a usage of 1.455 million tons. It is predicted that by 2024, my country's mulch film coverage area will reach 330 million mu (approximately 22.7 million hectares), with usage exceeding 2 million tons.

[0003] Currently, the raw material for mulch film production is mainly linear low-density polyethylene (LLDPE), compounded with small amounts of other resins or additives. Compared to low-density polyethylene (LDPE), LLDPE has higher tensile strength; compared to high-density polyethylene (HDPE), LLDPE has better tear resistance and transparency, making it more suitable for long-term outdoor use of mulch film. However, LLDPE is a copolymer of ethylene with 1-butene, 1-hexene, 1-octene, etc. The large number of short branches makes LLDPE's melt viscosity higher than HDPE, but its melt strength lower than LDPE. This not only causes instability in the blown film production process, but more seriously, uneven winding leads to substandard mulch film products, generating a lot of waste, and preventing the production of mulch film from meeting national requirements.

[0004] In the existing technology, three methods are generally adopted to improve the problem of uneven winding: (1) adding a certain amount of LDPE or HDPE to LLDPE raw materials to improve processing performance; (2) reducing the blow-up ratio; and (3) aligning and cutting the film roll at both ends. Although these three methods can solve or improve the problem of uneven winding in the production of mulch film, they also create new difficulties: blending with LDPE or HDPE is not suitable for resin production enterprises to add online because the amount added is large (more than 5 wt%), and can only be produced by post-blending, which not only prolongs the production process of mulch film and increases costs, but also easily causes unstable product performance; while reducing the blow-up ratio, the transverse tensile load and right-angle tear load of mulch film are also reduced accordingly, making it difficult to meet the national standard (GB 13735-2017); aligning and cutting the film roll at both ends increases the process and generates a large amount of waste film. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a linear low-density polyethylene composition for weather-resistant mulch film, its preparation method, and its application, to solve the problem of uneven winding during the mulch film production process caused by existing raw materials. The linear low-density polyethylene composition film of this invention exhibits significantly reduced roll misalignment width and no bursting during processing, while also improving tensile load, nominal strain at break, and right-angle tear resistance, thus achieving the dual purpose of improving resin processing performance and enhancing mechanical properties.

[0006] A first aspect of the present invention is to provide an LLDPE composition comprising an LLDPE resin, an inorganic particle / rubber particle composite, and optional additives; wherein the inorganic particle / rubber particle composite comprises inorganic particles and rubber particles coated on the surface of the inorganic particles, the inorganic particles having a mesh size of 800-4000 mesh, preferably 1500-3500 mesh, more preferably 1500-3000 mesh; and the rubber particles being rubber particles having a cross-linked structure.

[0007] In a preferred embodiment of the present invention, the content of inorganic particles in the inorganic particle / rubber particle composite is 50-80 wt%, preferably 60-80 wt%.

[0008] In a preferred embodiment of the present invention, the inorganic particles are selected from at least one of calcium carbonate, talc, montmorillonite, kaolin, titanium dioxide, and silicon dioxide, preferably from at least one of calcium carbonate, talc, and silicon dioxide, and most preferably from calcium carbonate.

[0009] In this invention, the inorganic particles may have the same or different shapes, and preferably, a single particle is spherical, elliptical, blocky, sheet-like, or irregular in shape.

[0010] In a preferred embodiment of the present invention, the smallest dimension of the inorganic particle in the three dimensions is not less than 1.0 micrometer, more preferably not less than 2.0 micrometer.

[0011] In a preferred embodiment of the present invention, the rubber particles have at least one of the following characteristics:

[0012] The rubber particles are selected from at least one of the following rubber particles having a cross-linked structure: styrene-butadiene rubber particles, carboxylated styrene-butadiene rubber particles, natural rubber particles, acrylate rubber particles, ethylene-vinyl acetate copolymer particles, isoprene rubber particles, and butadiene acrylate particles; preferably selected from at least one of styrene-butadiene rubber particles, carboxylated styrene-butadiene rubber particles, and ethylene-vinyl acetate copolymer particles, more preferably ethylene-vinyl acetate copolymer particles; and / or

[0013] The rubber particles have a gel content of 75% by weight or higher, preferably 85% by weight or higher; and / or,

[0014] The average particle size of the rubber particles is 20-500 nm, preferably 30-200 nm; and / or,

[0015] The rubber particles have a homogeneous structure.

[0016] The composite powder contained in this invention contains cross-linked powder rubber particles with a homogeneous structure, meaning that each individual rubber particle is homogeneous in composition, and no uneven phenomena such as layering or phase separation are found inside the particles under existing microscopic observation techniques.

[0017] The inorganic particle / rubber particle composite of the present invention can be prepared using inorganic particles of a specific mesh size as described in the present invention, using a preferred ratio of inorganic particles to rubber particles as described in the present invention, and using the method for preparing fully vulcanized powdered rubber disclosed in Chinese patent application CN99125530.5. The difference is that the irradiated crosslinked rubber latex is first mixed with the inorganic particle slurry, and then spray-dried while stirring to prepare the composite powder. The rubber latex raw materials used in the present invention include at least one of the following: styrene-butadiene rubber latex, carboxylated styrene-butadiene rubber latex, natural rubber latex, acrylate rubber latex, ethylene-vinyl acetate copolymer latex, isoprene rubber latex, acrylic-butadiene latex, preferably styrene-butadiene rubber latex, carboxylated styrene-butadiene rubber latex, and ethylene-vinyl acetate copolymer latex. The inorganic particle slurry used in the present invention is a dispersion of inorganic particles in water. Before being mixed with the rubber latex, it needs to be dispersed by general dispersion equipment (such as high-shear dispersing emulsifier, colloid mill, etc.) to ensure that the solid particles in the slurry can be uniformly dispersed in water. In this invention, the mass content of the solid component in the mixture of rubber latex and inorganic particle slurry is 10-65%, preferably 20-55%, and more preferably 30-50%.

[0018] According to the present invention, the inorganic particle / rubber particle composite can be prepared by the above method, or it can be prepared by using inorganic particles of a specific mesh size in the present invention, using the preferred ratio of inorganic particles / rubber particles in the present invention, and by selecting materials, with reference to the preparation method in CN1239587C.

[0019] In a preferred embodiment of the present invention, the LLDPE resin is copolymerized from ethylene and α-olefin, wherein the α-olefin is preferably selected from at least one of butene-1, hexene-1, and octene-1; preferably, under the conditions of 190±5℃ and a load of 2.16kg, the melt flow rate of the LLDPE resin is 0.3~3.0 g / 10min, more preferably 0.5~2.5 g / 10min, and more preferably 0.8~2.5 g / 10min.

[0020] In a preferred embodiment of the present invention, the LLDPE composition contains only one resin raw material, which is the LLDPE resin.

[0021] In a preferred embodiment of the present invention, the LLDPE resin content in the LLDPE composition is 96-99%, preferably 97-99%, and more preferably 98-99%. The composition contains only LLDPE as a resin raw material.

[0022] According to the present invention, the LLDPE composition may optionally contain additives. The additives of the present invention may also include commonly used additives in plastic processing, such as primary antioxidants, secondary antioxidants, light stabilizers, ultraviolet absorbers, antistatic agents, slip agents, etc. The dosages are all conventional dosages, or may be adjusted according to actual requirements.

[0023] In a preferred embodiment of the present invention, the LLDPE composition contains additives; preferably, the additives include one or more of the following: primary antioxidant, secondary antioxidant, light stabilizer, ultraviolet absorber, antistatic agent, and slip agent.

[0024] In a preferred embodiment of the present invention, the additive includes a light stabilizer; preferably:

[0025] Based on parts by weight, in the LLDPE composition, the amount of the light stabilizer is 0.1-1 parts, preferably 0.2-0.8 parts, relative to 100 parts of LLDPE resin; and / or,

[0026] The light stabilizer is one or more of hindered amine light stabilizers and ultraviolet absorbers. Preferably, the light stabilizer is a hindered amine light stabilizer and / or a hindered amine synergistic light stabilizer. More preferably, the hindered amine light stabilizer is selected from at least one of 770, 944, 622, and 3346, and the hindered amine synergistic light stabilizer is selected from at least one of HS-362, 962, 783, T-69, T-68, and T-66.

[0027] In a preferred embodiment of the present invention, the adjuvant includes a primary antioxidant and a secondary antioxidant.

[0028] In a preferred embodiment of the present invention, the amount of the primary antioxidant in the LLDPE composition, relative to 100 parts of LLDPE resin, is 0.02-0.1 parts, preferably 0.03-0.06 parts; and the amount of the secondary antioxidant is 0.02-0.15 parts, preferably 0.03-0.1 parts.

[0029] In a more preferred embodiment of the present invention, the primary antioxidant is a hindered phenolic antioxidant, preferably selected from at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 1,3,5-trimethyl-2,4,6-(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanuric acid, isooctyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione.

[0030] In a more preferred embodiment of the present invention, the auxiliary antioxidant is selected from phosphite and / or thioester antioxidants, preferably from phosphites, including at least one of tris(nonylphenyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, bis(octadecyl) pentaerythritol diphosphite, pentaerythritol bis(2,4-tert-butylphenyl) diphosphite, bis(2,6-di-tert-butyl-4-tolyl) pentaerythritol phosphite, tetrakis(2,4-di-tert-butyloctaalkoxy-4,4'-biphenyl) phosphate, and 2,2-ethylidene bis(4,6-di-tert-butylphenyl) fluorophosphite.

[0031] In a preferred embodiment of the present invention, the content of the inorganic particle / rubber particle composite in the LLDPE composition is 0.3-3 parts by weight, preferably 0.5-2 parts, relative to 100 parts of LLDPE resin.

[0032] In a preferred embodiment of the present invention, the LLDPE composition comprises the following components: LLDPE resin alone, the inorganic particle / rubber particle composite, and other additives blended together. The LLDPE composition contains 96-99% LLDPE by mass, 0.5-3% inorganic particle / rubber particle composite by mass, and 0.5-1.0% other additives by mass, making it highly suitable as a raw material for mulch film production.

[0033] Compared to existing technologies that address uneven winding by adding a certain amount of LDPE or HDPE to the LLDPE raw material or reducing the blow-up ratio, this invention provides a solution using only one LLDPE resin raw material, an inorganic particle / rubber particle composite, and optional processing aids to prepare a single composition. This solves the problem of uneven winding during mulch film production caused by existing raw materials (especially under high blow-up ratios (>2.7)). The inorganic particle / rubber particle composite, formed by irradiation-crosslinked rubber particles covering the surface of inorganic particles, is blended with LLDPE, improving the interaction between the inorganic particles and LLDPE interface. Simultaneously, after irradiation crosslinking, the rubber particles no longer adhere to each other, thus reducing the adhesive force between films. This improves the extrusion blow-up process, resulting in neater film winding. This not only reduces waste film generation and improves production efficiency but also eliminates the need for LLDPE, LDPE, or HDPE resin compounding, simplifying the process and reducing production costs.

[0034] Uneven winding refers to a misalignment width of more than 30 mm or the appearance of bursting ribs in the film roll.

[0035] A second aspect of the present invention is to provide a method for preparing the LLDPE composition described in the first aspect, comprising the step of melt-mixing raw materials including the LLDPE resin, an inorganic particle / rubber particle composite, and optional additives; preferably,

[0036] First, the raw materials, including the LLDPE resin, the inorganic particle / rubber particle composite and optional additives, are premixed to obtain a premixed composition; then, the obtained premixed composition is melt-blended to obtain the LLDPE composition.

[0037] During the preparation process, the blending temperature of the materials corresponds to the typical processing temperature of the LLDPE matrix resin, and should be selected within a range that ensures complete melting of the matrix resin without causing its decomposition. Furthermore, depending on processing requirements, appropriate amounts of conventional plastic processing additives, such as antistatic agents, lubricants, and slip agents, can be added to the blended materials. During the blending process, the components can be simultaneously added to a melt blending device via metering or other methods for melt blending; alternatively, the components can be pre-mixed uniformly using general-purpose mixing equipment, and then melt-blended and extruded in a rubber-plastic blending device to obtain the modified resin composition.

[0038] The rubber-plastic blending equipment used in the preparation method of this invention can be an open mill, internal mixer, single-screw extruder, twin-screw extruder, or twin-rotor extruder, etc. The material mixing equipment is selected from commonly used mechanical mixing equipment in the art, such as high-speed mixers and kneaders.

[0039] A third aspect of the present invention is to provide an LLDPE membrane, wherein the LLDPE membrane is made of an LLDPE composition, wherein the LLDPE composition is the LLDPE composition described in the first aspect or a composition prepared by the preparation method described in the second aspect; preferably, the blow-up ratio is >2.7.

[0040] A fourth aspect of the present invention is to provide a method for preparing the LLDPE film described in the third aspect, comprising molding the LLDPE composition described in the first aspect or the LLDPE composition prepared by the preparation method described in the second aspect using a blow molding method to obtain the LLDPE film, preferably, the blow-up ratio is >2.7.

[0041] The fifth aspect of the present invention is to provide an application of the LLDPE film described in the third aspect or the LLDPE film obtained by the preparation method described in the fourth aspect as a mulch film or a stretch film.

[0042] As mentioned above, three methods are generally adopted to improve the problem of uneven winding: (1) adding a certain amount of LDPE or HDPE to LLDPE raw materials to improve processing performance; (2) reducing the blow-up ratio; and (3) aligning and cutting the film roll at both ends. Although these three methods can solve or improve the problem of uneven winding in the production of mulch film, they also create new difficulties: blending with LDPE or HDPE is not suitable for resin production enterprises to add online because the amount added is large (more than 5 wt%), and can only be produced by post-blending, which not only prolongs the mulch film production process and increases costs, but also easily causes unstable product performance; while reducing the blow-up ratio, the transverse tensile load and right-angle tear load of the mulch film are also reduced accordingly.

[0043] During the research process, the inventors unexpectedly discovered that blending the specific inorganic particle / rubber particle composite of the present invention with LLDPE can reduce the adhesion between films and improve the extrusion blow molding process. Of particular significance is that it makes the film winding more uniform, which solves the technical problem that existing LLDPE requires the addition of other components (LDPE or HDPE) to blow mold ultra-thin mulch films to improve processing performance. The present invention can be successfully processed and molded using a single homogeneous LLDPE.

[0044] Verification has shown that the nominal 10-micron thick mulch film of this invention exhibits significantly reduced film roll misalignment width and no bursting during processing. Furthermore, it demonstrates improved tensile load, nominal strain at break, and right-angle tear resistance, achieving the dual objectives of improving resin processing performance and enhancing mechanical properties.

[0045] This invention improves the extrusion blow molding process, resulting in neater film winding. This not only reduces waste film generation and improves production efficiency, but also eliminates the need for LLDPE, LDPE, or HDPE resin compounding, simplifying the process and reducing production costs. Detailed Implementation

[0046] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0047] The present invention will be further described below with reference to embodiments. These embodiments are merely possible technical implementations of the present invention and do not represent all possible implementations. Those skilled in the art can, in conjunction with the embodiments of the present invention, obtain other embodiments without inventive effort, and these embodiments are also within the protection scope of the present invention. The scope of the claims of the present invention is not limited to these embodiments, but is set forth in the appended claims.

[0048] The experimental data in this embodiment were measured using the following instruments and methods:

[0049] The test specimens for tensile load and nominal strain at break were tested in accordance with the national standard GB / T1040.3-2006 and the local standard of Xinjiang Uygur Autonomous Region DB653189-2014. The specimens were type 2, with a width of 10 mm, an initial mark distance of 50 mm between the fixtures, a test speed (no load) of 500 mm / min, and were stretched until the specimen broke. The maximum tensile load was measured to an accuracy of 0.01 N.

[0050] Right-angle tear load testing was conducted according to the national standard GB / T1130-1991 and the Xinjiang Uygur Autonomous Region local standard DB653189-2014. Single-piece specimens were used, with an initial mark distance of 55 mm between the fixtures, and a test speed (unloaded) of 200 mm / min. The arithmetic mean of the experimental results was taken.

[0051] Melt index test temperature 190±5℃, load 2.16 kg.

[0052] The membrane roll misalignment width is a quantitative parameter that describes the neatness of the membrane roll winding. Single-layer winding refers to the difference between the width of the membrane roll and the nominal width of the membrane, while double-layer winding refers to the difference between the width of the membrane roll and the folded diameter of the membrane.

[0053] Uneven winding refers to a misalignment width of more than 30 mm or the appearance of bursting ribs in the film roll.

[0054] The preparation process of the inorganic particle / rubber particle composite is based on patent CN1239587C. The parameters of calcium carbonate, rubber latex, and proportions in this invention are described in the various embodiments.

[0055] The mulch film preparation process in the following examples and comparative examples is as follows:

[0056] The initial mixing and melt blending process of the materials is as follows: First, all materials are weighed according to the proportion and initially mixed in a high-speed mixer for 20 seconds. Then, a twin-screw extruder (Coperon (Nanjing) Machinery Co., Ltd., length-to-diameter ratio 30:1, screw diameter 30 mm) is used for melt blending and granulation. The speed is 200 r / min, and the temperature is set to 170℃, 180℃, 190℃, 200℃, 200℃, 200℃, and the feed rate is 14. The resulting granules are placed in a tray and treated in a 70℃ oven for 4 hours to remove moisture.

[0057] The mulch film was prepared using a double-layer blow molding method. The blow molding machine was a German company, Kölin. The temperature settings of the blow molding machine were as follows: 160℃, 180℃, 200℃, 210℃, 210℃, 210℃, and 210℃ for each section. The screw speed was 40 r / min. The blown film width was 31.0 cm, the nominal thickness was 10.0 μm, and the blow-up ratio was 3.0.

[0058] Example 1:

[0059] Weigh the LLDPE resin powder (Chemical Branch of Zhongtian Hechuang Energy Co., Ltd., melt index: 1.0 g / 10min, density: 0.918 g / cm³). 3 2000 g of antioxidant 1010 (Yingkou Fengguang New Materials Co., Ltd.), 1.0 g of primary antioxidant 1010 (Yingkou Fengguang New Materials Co., Ltd.), 1.2 g of secondary antioxidant 168 (Yingkou Fengguang New Materials Co., Ltd.), 6.0 g of hindered amine light stabilizer 944 (Beijing Tiangang Additives Co., Ltd.), and 10.0 g of calcium carbonate / styrene-butadiene rubber composite particles (prepared by Beijing Chemical Research Institute, with a calcium carbonate:styrene-butadiene rubber particle mass ratio of 80:20; where calcium carbonate: Lingshou County Guanghui Mineral Products Processing Co., Ltd., mesh size 1000; styrene-butadiene rubber emulsion: Yanshan Petrochemical High-Tech Co., Ltd.) were dispersed evenly in a high-speed mixer, then melt-blended and granulated by a twin-screw extruder. Blown mulch film: nominal thickness 10.0 μm, blow-up ratio 3.0. The longitudinal / transverse tensile load, nominal strain at break, right-angle tear load, membrane roll misalignment width, and number of bursts were tested.

[0060] Example 2:

[0061] Weigh the LLDPE resin powder (Chemical Branch of Zhongtian Hechuang Energy Co., Ltd., melt index: 1.0 g / 10min, density: 0.918 g / cm³). 32000 g of antioxidant 1010 (Yingkou Fengguang New Materials Co., Ltd.), 1.0 g of primary antioxidant 1010 (Yingkou Fengguang New Materials Co., Ltd.), 1.2 g of secondary antioxidant 168 (Yingkou Fengguang New Materials Co., Ltd.), 6.0 g of hindered amine light stabilizer 944 (Beijing Tiangang Additives Co., Ltd.), and 16.0 g of calcium carbonate / styrene-butadiene rubber composite particles (prepared by Beijing Chemical Research Institute, with a calcium carbonate:styrene-butadiene rubber particle mass ratio of 80:20, where calcium carbonate is from Lingshou County Guanghui Mineral Products Processing Co., Ltd., mesh size 2000; and styrene-butadiene rubber emulsion is from Yanshan Petrochemical High-Tech Co., Ltd.) were dispersed evenly in a high-speed mixer, then melt-blended and granulated using a twin-screw extruder. Blown mulch film: nominal thickness 10.0 μm, blow-up ratio 3.0. The longitudinal / transverse tensile load, nominal strain at break, right-angle tear load, membrane roll misalignment width, and number of bursts were tested.

[0062] Example 3:

[0063] Weigh the LLDPE resin powder (Chemical Branch of Zhongtian Hechuang Energy Co., Ltd., melt index: 1.0 g / 10min, density: 0.918 g / cm³). 3 2000g of antioxidant 1010 (Yingkou Fengguang New Materials Co., Ltd.), 1.0g of primary antioxidant 1010 (Yingkou Fengguang New Materials Co., Ltd.), 1.2g of secondary antioxidant 168 (Yingkou Fengguang New Materials Co., Ltd.), 6.0g of hindered amine light stabilizer 944 (Beijing Tiangang Additives Co., Ltd.), and 20.0g of calcium carbonate / styrene-butadiene rubber composite particles (prepared by Beijing Chemical Research Institute, with a calcium carbonate:styrene-butadiene rubber particle mass ratio of 70:30, where calcium carbonate is from Lingshou County Guanghui Mineral Products Processing Co., Ltd., mesh size 3000; and styrene-butadiene rubber emulsion is from Yanshan Petrochemical High-Tech Co., Ltd.) were dispersed evenly in a high-speed mixer, then melt-blended and granulated using a twin-screw extruder. Blown mulch film: nominal thickness 10.0 μm, blow-up ratio 3.0. The longitudinal / transverse tensile load, nominal strain at break, right-angle tear load, membrane roll misalignment width, and number of bursts were tested.

[0064] Example 4:

[0065] Weigh the LLDPE resin powder (Chemical Branch of Zhongtian Hechuang Energy Co., Ltd., melt index: 1.0 g / 10min, density: 0.918 g / cm³). 32000 g of antioxidant 1010 (Yingkou Fengguang New Materials Co., Ltd.), 1.0 g of primary antioxidant 1010 (Yingkou Fengguang New Materials Co., Ltd.), 1.2 g of secondary antioxidant 168 (Yingkou Fengguang New Materials Co., Ltd.), 6.0 g of hindered amine light stabilizer 622 (Beijing Tiangang Additives Co., Ltd.), and 20.0 g of talc / styrene-butadiene rubber composite particles (prepared by Beijing Chemical Research Institute, talc:styrene-butadiene rubber particle mass ratio of 60:40, where talc is from Guangxi Longguang Talc Development Co., Ltd., mesh size 2000; and styrene-butadiene rubber emulsion is from Yanshan Petrochemical High-Tech Co., Ltd.) were dispersed evenly in a high-speed mixer, then melt-blended and granulated using a twin-screw extruder. Blown mulch film: nominal thickness 10.0 μm, blow-up ratio 3.0. The longitudinal / transverse tensile load, nominal strain at break, right-angle tear load, membrane roll misalignment width, and number of bursts were tested.

[0066] Example 5:

[0067] Weigh the LLDPE resin powder (Chemical Branch of Zhongtian Hechuang Energy Co., Ltd., melt index: 1.0 g / 10min, density: 0.918 g / cm³). 3 2000 g of antioxidant 1010 (Yingkou Fengguang New Materials Co., Ltd.), 1.0 g of primary antioxidant 1010 (Yingkou Fengguang New Materials Co., Ltd.), 1.2 g of secondary antioxidant 168 (Yingkou Fengguang New Materials Co., Ltd.), 6.0 g of synergistic compound light stabilizer HS-362 (Beijing Tiangang Additives Co., Ltd.), and 20.0 g of talc / polyethylene-vinyl acetate rubber composite particles (prepared by Beijing Chemical Research Institute, talc:polyethylene-vinyl acetate rubber particle mass ratio of 70:30, where talc: Guangxi Longguang Talc Development Co., Ltd., mesh size 2000; polyethylene-vinyl acetate rubber emulsion, Yanshan Petrochemical High-Tech Co., Ltd.) were dispersed evenly in a high-speed mixer, then melt-blended and granulated by twin-screw extruder. Blown mulch film: nominal thickness 10 μm, blow-up ratio 3.0. The longitudinal / transverse tensile load, nominal strain at break, right-angle tear load, film roll misalignment width, and number of bursts were tested.

[0068] Example 6:

[0069] Weigh the LLDPE resin powder (Chemical Branch of Zhongtian Hechuang Energy Co., Ltd., melt index: 1.0 g / 10min, density: 0.918 g / cm³). 32000g of antioxidant 1010 (Yingkou Fengguang New Materials Co., Ltd.), 1.0g of primary antioxidant 1010 (Yingkou Fengguang New Materials Co., Ltd.), 1.2g of secondary antioxidant 168 (Yingkou Fengguang New Materials Co., Ltd.), 6.0g of hindered amine light stabilizer 944 (Beijing Tiangang Additives Co., Ltd.), and 20.0g of calcium carbonate / polyethylene-vinyl acetate rubber particle composite (prepared by Beijing Chemical Research Institute, with a calcium carbonate:polyethylene-vinyl acetate rubber particle mass ratio of 70:30, where calcium carbonate: Lingshou County Guanghui Mineral Products Processing Co., Ltd., mesh size 2000; polyethylene-vinyl acetate rubber emulsion: Yanshan Petrochemical High-Tech Co., Ltd.) were dispersed evenly in a high-speed mixer, then melt-blended and granulated using a twin-screw extruder. Blown mulch film: nominal thickness 10.0 μm, blow-up ratio 3.0. The longitudinal / transverse tensile load, nominal strain at break, right-angle tear load, film roll misalignment width, and number of bursts were tested.

[0070] Comparative Example 1:

[0071] Weigh the LLDPE resin powder (Chemical Branch of Zhongtian Hechuang Energy Co., Ltd., melt index: 1.0 g / 10min, density: 0.918 g / cm³). 3 2000 g of antioxidant 1010 (Yingkou Fengguang New Materials Co., Ltd.), 1.0 g of primary antioxidant 1010, 1.2 g of secondary antioxidant 168 (Yingkou Fengguang New Materials Co., Ltd.), and 6.0 g of hindered amine light stabilizer 944 (Beijing Tiangang Additives Co., Ltd.) were dispersed evenly in a high-speed mixer, then melt-blended and granulated using a twin-screw extruder. The blown mulch film had a nominal thickness of 10.0 μm and a blow-up ratio of 3.0, but the blown film was unstable. The longitudinal / transverse tensile load, nominal strain at break, right-angle tear load, film roll misalignment width, and number of bursts were tested.

[0072] Comparative Example 2:

[0073] Weigh the LLDPE resin powder (Chemical Branch of Zhongtian Hechuang Energy Co., Ltd., melt index: 1.0 g / 10min, density: 0.918 g / cm³). 3 2000 g of antioxidant 1010 (Yingkou Fengguang New Materials Co., Ltd.), 1.0 g of primary antioxidant 1010 (Yingkou Fengguang New Materials Co., Ltd.), 1.2 g of secondary antioxidant 168 (Yingkou Fengguang New Materials Co., Ltd.), 16.0 g of hindered amine light stabilizer 944 (Beijing Tiangang Additives Co., Ltd.), and 10.0 g of calcium carbonate (Lingshou County Guanghui Mineral Products Processing Co., Ltd., mesh size 2000) were dispersed evenly in a high-speed mixer, then melt-blended and granulated using a twin-screw extruder. The blown mulch film had a nominal thickness of 10.0 μm and a blow-up ratio of 3.0. The longitudinal / transverse tensile load, nominal strain at break, right-angle tear load, roll misalignment width, and number of bursts were tested.

[0074] Comparative Example 3

[0075] The mulch film was prepared according to the method in Example 6, except that 2000-mesh calcium carbonate was replaced with 200-mesh calcium carbonate, while the rest remained the same. The average particle size of the calcium carbonate was 74 micrometers. Under high blow-up ratio conditions, when blowing a film of approximately 10 micrometers, the primary calcium carbonate particles were too large. After the film melt exited the die, it fractured during traction cooling, leading to film breakage and production difficulties. A sample of the remaining film was taken for mechanical property testing, and the results are shown in the table below.

[0076] Table 1. Physical and mechanical properties of 10-micron thick mulch film prepared using the LLDPE composition of this invention as raw material and blown film process status.

[0077]

[0078] As shown in Table 1, the tensile load, nominal strain at break, right-angle tear performance, film roll misalignment width, and number of bursts of Examples 1-6 are significantly better than those of Comparative Examples 1-3, achieving the dual purpose of improving mechanical properties and resin processing performance.

[0079] The LLDPE resin in the above examples was replaced with other types of LLDPE resin, other types of rubber latex as described in this invention, other types of inorganic particles as described in this invention, other types of light stabilizers as described in this invention, and other types of antioxidants as described in this invention. The examples obtained by changing one or more of the above factors were verified using the same method as Examples 1-6. It was found that the test results of the example samples were similar to those of Examples 1-6, and were significantly better than those of the comparative examples.

[0080] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

[0081] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0082] When this specification uses the prefixes "known to those skilled in the art," "prior art," or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those conventionally used in the art at the time the invention was proposed, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0083] The endpoints and any values ​​of the ranges disclosed in this invention document are not limited to the precise ranges or values; these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. In the following, various technical solutions can, in principle, be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0084] In the context of this specification, except where expressly stated otherwise, any matters or issues not mentioned shall apply directly to those known in the art without any modification.

[0085] Furthermore, any implementation described herein can be freely combined with one or more other implementations described herein, and the resulting technical solutions or technical ideas shall be regarded as part of the original disclosure or original record of the present invention, and should not be regarded as new content not disclosed or anticipated herein, unless those skilled in the art consider the combination to be obviously unreasonable.

Claims

1. An LLDPE composition comprising LLDPE resin, an inorganic particle / rubber particle complex, and optional additives; wherein, The inorganic particle / rubber particle composite contains inorganic particles and rubber particles coated on the surface of the inorganic particles. The inorganic particles have a mesh size of 800 to 4000 mesh. The rubber particles are rubber particles with a cross-linked structure. The rubber particles have a gel content of 75% by weight or higher, and the average particle size of the rubber particles is 20 to 500 nm. The inorganic particle / rubber particle composite contains 50-80 wt% inorganic particles. Based on parts by weight, the content of the inorganic particle / rubber particle composite in the LLDPE composition is 0.3-3 parts relative to 100 parts of LLDPE resin.

2. The LLDPE composition according to claim 1, characterized in that: The inorganic particles have a mesh size of 1500-3500 mesh.

3. The LLDPE composition according to claim 1, characterized in that: The inorganic particles have a mesh size of 1500-3000 mesh.

4. The LLDPE composition according to claim 1, characterized in that: The inorganic particles are selected from at least one of calcium carbonate, talc, montmorillonite, kaolin, titanium dioxide, and silicon dioxide; and / or, The inorganic particles may have the same or different shapes; and / or, The smallest dimension of the inorganic particle in its three dimensions is not less than 1.0 micrometer.

5. The LLDPE composition according to claim 1, characterized in that: The inorganic particle / rubber particle composite contains 60-80 wt% inorganic particles; and / or, The inorganic particles are selected from at least one of calcium carbonate, talc, and silicon dioxide; and / or, The inorganic particles may have the same or different shapes, and individual particles may be spherical, elliptical, blocky, plate-like, or irregular in shape; and / or, The smallest dimension of the inorganic particle in its three dimensions is not less than 2.0 micrometers.

6. The LLDPE composition according to claim 1, characterized in that: The rubber particles are selected from at least one of the following rubber particles having a cross-linked structure: styrene-butadiene rubber particles, carboxylated styrene-butadiene rubber particles, natural rubber particles, acrylate rubber particles, ethylene-vinyl acetate copolymer particles, isoprene rubber particles, and butadiene acrylate particles; and / or, The rubber particles have a gel content of 85% by weight or higher; and / or, The average particle size of the rubber particles is 30~200 nm; and / or, The rubber particles have a homogeneous structure.

7. The LLDPE composition according to claim 1, characterized in that: The rubber particles are selected from at least one of styrene-butadiene rubber particles, carboxylated styrene-butadiene rubber particles, and ethylene-vinyl acetate copolymer particles.

8. The LLDPE composition according to claim 1, characterized in that: The LLDPE resin is copolymerized from ethylene and α-olefin.

9. The LLDPE composition according to claim 8, characterized in that: The α-olefin is selected from at least one of butene-1, hexene-1, and octene-1.

10. The LLDPE composition according to claim 8, characterized in that: At 190±5℃ and a load of 2.16 kg, the melt flow rate of the LLDPE resin is 0.3~3.0 g / 10min.

11. The LLDPE composition according to claim 8, characterized in that: At 190±5℃ and a load of 2.16 kg, the melt flow rate of the LLDPE resin is 0.5~2.5 g / 10min.

12. The LLDPE composition according to claim 8, characterized in that: The LLDPE composition contains only one resin raw material, which is LLDPE resin.

13. The LLDPE composition according to claim 1, characterized in that: The LLDPE composition contains additives.

14. The LLDPE composition according to claim 13, characterized in that: The additives include one or more of the following: primary antioxidants, secondary antioxidants, light stabilizers, ultraviolet absorbers, antistatic agents, and slip agents.

15. The LLDPE composition according to claim 13, characterized in that: The additives include light stabilizers.

16. The LLDPE composition according to claim 15, characterized in that: Based on parts by weight, the amount of the light stabilizer in the LLDPE composition is 0.1-1 parts relative to 100 parts of LLDPE resin; and / or, The light stabilizer is one or more of hindered amine light stabilizers and ultraviolet absorbers.

17. The LLDPE composition according to claim 15, characterized in that: Based on parts by weight, the amount of light stabilizer in the LLDPE composition is 0.2-0.8 parts relative to 100 parts of LLDPE resin.

18. The LLDPE composition according to claim 15, characterized in that: The light stabilizer is a hindered amine light stabilizer and / or a hindered amine synergistic light stabilizer.

19. The LLDPE composition according to claim 18, characterized in that: The hindered amine light stabilizer is selected from at least one of 770, 944, 622, and 3346, and the hindered amine synergistic light stabilizer is selected from at least one of HS-362, 962, 783, T-69, T-68, and T-66.

20. The LLDPE composition according to claim 13, characterized in that: The adjuvants include primary antioxidants and secondary antioxidants.

21. The LLDPE composition according to claim 20, characterized in that: Based on parts by weight, in the LLDPE composition, the amount of the primary antioxidant is 0.02-0.1 parts relative to 100 parts of LLDPE resin; and the amount of the secondary antioxidant is 0.02-0.15 parts.

22. The LLDPE composition according to claim 20, characterized in that: Based on parts by weight, in the LLDPE composition, the amount of the primary antioxidant is 0.03-0.06 parts relative to 100 parts of LLDPE resin; and the amount of the secondary antioxidant is 0.03-0.1 parts.

23. The LLDPE composition according to claim 20, characterized in that: The primary antioxidant is a hindered phenolic antioxidant; and / or... The auxiliary antioxidant is selected from phosphite and / or thioester antioxidants.

24. The LLDPE composition according to claim 20, characterized in that: The primary antioxidant is selected from at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 1,3,5-trimethyl-2,4,6-(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanuric acid, isooctyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione.

25. The LLDPE composition according to claim 20, characterized in that: The co-antioxidant is selected from phosphites, including at least one of tris(nonylphenyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, bis(octadecyl) pentaerythritol diphosphite, pentaerythritol bis(2,4-tert-butylphenyl) diphosphite, bis(2,6-di-tert-butyl-4-tolyl) pentaerythritol phosphite, tetrakis(2,4-di-tert-butyloctaalkoxy-4,4'-biphenyl) phosphate, and 2,2-ethylidene bis(4,6-di-tert-butylphenyl) fluorophosphite.

26. The LLDPE composition according to any one of claims 1-25, characterized in that: Based on parts by weight, the content of the inorganic particle / rubber particle composite in the LLDPE composition is 0.5-2 parts relative to 100 parts of LLDPE resin.

27. A method for preparing an LLDPE composition according to any one of claims 1-26, comprising the step of melt-mixing raw materials including the LLDPE resin, an inorganic particle / rubber particle composite and optional additives.

28. The method for preparing the LLDPE composition according to claim 27, characterized in that: First, raw materials including LLDPE resin, inorganic particle / rubber particle composite and optional additives are premixed to obtain a premixed composition; then, the obtained premixed composition is melt-blended to obtain the LLDPE composition.

29. An LLDPE membrane, wherein the LLDPE membrane is made of an LLDPE composition, wherein the LLDPE composition is any one of claims 1-26 or a composition prepared by the preparation method described in claim 27 or 28.

30. A method for preparing the LLDPE film according to claim 29, comprising molding the LLDPE composition according to any one of claims 1-26 or the LLDPE composition prepared by the preparation method according to claim 27 or 28 by blow molding to obtain the LLDPE film.

31. The method for preparing the LLDPE membrane according to claim 30, characterized in that: Inflation ratio > 2.

7.

32. The application of the LLDPE membrane of claim 29 or the LLDPE membrane obtained by the preparation method of claim 30 or 31 as a mulch film or a stretch film.

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