Linear low-density polyethylene composition for weather-resistant mulching film as well as preparation method and application of linear low-density polyethylene composition

Abstract

The invention provides a linear low-density polyethylene composition for a weather-resistant mulching film as well as a preparation method and application of the linear low-density polyethylene composition. The composition contains LLDPE resin, an inorganic particle / rubber particle compound and an optional auxiliary agent, wherein the inorganic particle / rubber particle compound contains inorganic particles and rubber particles covering the surfaces of the inorganic particles, and the mesh number of the inorganic particles is 800 to 4000 meshes, preferably 1500 to 3500 meshes, and more preferably 1500 to 3000 meshes; the rubber particles are rubber particles with a cross-linked structure. The problem of uneven rolling in the mulching film production process (especially under the condition of high blow-up ratio) caused by existing raw materials is solved, the extrusion blowing process can be improved, the film is rolled more orderly, waste films are reduced, the production efficiency is improved, the LLDPE, LDPE or HDPE resin compounding production link is omitted, the technological process is simplified, and the production cost is reduced.

Description

Technical Field

[0001] The present invention relates to a polyolefin composition, and more particularly to a linear low-density polyethylene composition for weather-resistant ground film, and a preparation method and application thereof. Background Art

[0002] Agricultural ground covering film (referred to as ground film) has the functions of retaining moisture, increasing temperature and saving water, making important contributions to increasing agricultural production and farmers' income, and has become an indispensable means of production for agricultural production. my country is the world's largest country in terms of agricultural ground film production and coverage area, accounting for 75% of the world's total production.

[0003] At present, the raw materials for the production of ground film are mainly linear low-density polyethylene, compounded with a small amount of other resins or additives. Compared with low-density polyethylene (LDPE), LLDPE (linear low-density polyethylene) has higher tensile strength; compared with high-density polyethylene (HDPE), LLDPE has better tearing performance and transparency, so it is more suitable for the long-term use of ground film in the field. However, LLDPE is a copolymer of ethylene and 1-butene, 1-hexene, 1-octene, etc. A large number of short chain branches make the melt viscosity of LLDPE higher than that of HDPE, but the melt strength is lower than that of LDPE. This not only causes the unstable production process of ground film blowing, but the more serious problem is that the uneven winding leads to unqualified ground film products, generating a lot of waste, and the production of ground film cannot meet the requirements of national and Xinjiang Uygur Autonomous Region local standards.

[0004] In the prior art, three methods are generally used to improve the problem of uneven winding: (1) adding a certain amount of LDPE or HDPE to the LLDPE raw material to improve processing performance, (2) reducing the blow-up ratio, and (3) aligning and cutting the two ends of the film roll. Although these three methods can solve or improve the problem of uneven winding in the production of ground film, they also create new difficulties: blending with LDPE or HDPE is not suitable for online addition by resin manufacturers because the addition amount is large (more than 5wt%), and can only be produced by post-mixing, which not only prolongs the ground film production process and increases costs, but also easily causes unstable product performance; while reducing the blow-up ratio, the lateral tensile load and right-angle tearing load of the ground film are also reduced accordingly, making it difficult to meet the national standard (GB 13735-2017) and the local standard of the Xinjiang Uygur Autonomous Region (DB / T 3189-2014), and aligning and cutting the two ends of the film roll increases the process flow and produces a large amount of waste film. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a linear low-density polyethylene composition for weather-resistant ground film and its preparation method and application, so as to solve the problem of uneven winding in the ground film production process caused by existing raw materials. The linear low-density polyethylene composition film of the present invention has a greatly reduced film roll dislocation width during processing, no rib burst, and improved tensile load, nominal strain at break and right-angle tearing performance, achieving the dual purpose of improving the resin processing performance while improving the mechanical properties.

[0006] The first aspect of the present invention is to provide an LLDPE composition, comprising an LLDPE resin, an inorganic particle / rubber particle composite and an optional auxiliary agent; wherein the inorganic particle / rubber particle composite comprises inorganic particles and rubber particles coated on the surface of the inorganic particles, the mesh size of the inorganic particles is 800 to 4000 mesh, preferably 1500 to 3500 mesh, and more preferably 1500 to 3000 mesh; the rubber particles are rubber particles with 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 50-80wt%, preferably 60-80wt%.

[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 selected from at least one of calcium carbonate, talc and silicon dioxide, and most preferably calcium carbonate.

[0009] In the present invention, the shapes of the particles in the inorganic particles are the same or different, and preferably, a single particle is spherical, elliptical, blocky, flake-shaped or irregular in shape.

[0010] In a preferred embodiment of the present invention, the smallest dimension of the three dimensions of the inorganic particles 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, acrylic rubber particles, ethylene-vinyl acetate copolymer particles, isoprene rubber particles, and acrylic acid-butadiene particles; preferably selected from at least one of styrene-butadiene rubber particles, carboxylated styrene-butadiene rubber particles, and ethylene-vinyl acetate copolymer particles, and more preferably ethylene-vinyl acetate copolymer particles; and / or,

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

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

[0015] The rubber particles are of a homogeneous structure.

[0016] The powder rubber particles with a cross-linked structure contained in the composite powder of the present invention are of a homogeneous structure, that is, the individual rubber particles are homogeneous in composition, and no uneven phenomena such as stratification and phase separation are found inside the particles under observation using existing microscopic techniques.

[0017] The inorganic particle / rubber particle composite of the present invention can be prepared by using the inorganic particles of the specific mesh number in the present invention, the preferred ratio of the inorganic particles / rubber particles in the present invention, and the material selection, and the method for preparing fully vulcanized powdered rubber disclosed in the Chinese patent application CN99125530.5, except that the irradiated cross-linked rubber latex is first mixed with the inorganic particle slurry, and then spray-dried under stirring to prepare the composite powder. The rubber latex raw material used in the present invention includes at least one of the following: styrene-butadiene rubber latex, carboxylated styrene-butadiene rubber latex, natural rubber latex, acrylic ester rubber latex, ethylene-vinyl acetate copolymer latex, isoprene rubber latex, acrylic acid-butadiene emulsion, preferably styrene-butadiene rubber latex, carboxylated styrene-butadiene rubber latex, ethylene-vinyl acetate copolymer latex. The inorganic particle slurry used in the present invention is a dispersion of inorganic particles in water, which needs to be dispersed by a general dispersing device (such as a high shear dispersing emulsifier, a colloid mill, etc.) before mixing with the rubber latex to ensure that the solid particles in the slurry can be evenly dispersed in water. The mass content of the solid component in the mixture of the rubber latex and the inorganic particle slurry in the present invention is 10-65%, preferably 20-55%, more preferably 30-50%.

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

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

[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 mass content of LLDPE resin in the LLDPE composition is 96-99%, preferably 97-99%, more preferably 98-99%. The composition contains only one resin raw material, namely LLDPE.

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

[0023] In a preferred embodiment of the present invention, the LLDPE composition contains an auxiliary agent; preferably, the auxiliary agent includes one or more of a primary antioxidant, a secondary antioxidant, a light stabilizer, a UV absorber, an antistatic agent, and a lubricant.

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

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

[0026] The light stabilizer is one or more of a hindered amine light stabilizer and an ultraviolet absorber. 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 auxiliary agent includes a primary antioxidant and a secondary antioxidant.

[0028] In a preferred embodiment of the present invention, in the LLDPE composition, the amount of the primary antioxidant is 0.02-0.1 parts, preferably 0.03-0.06 parts, relative to 100 parts of LLDPE resin, 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 phenol antioxidant, preferably selected from at least one of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] pentaerythritol ester, 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, 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 phosphites and / or thioester antioxidants, preferably selected from phosphites, including at least one of tris(nonylphenyl)phosphite, tris(2,4-di-tert-butylphenyl)phosphite, bis(octadecyl)pentaerythritol diphosphite, pentaerythritol bis(diphosphite (2,4-tert-butylphenyl) ester, bis(2,6-di-tert-butyl-4-tolyl)pentaerythritol phosphite, tetrakis(2,4-di-tert-butyloctaalkoxy-4,4'-biphenyl) phosphate, and 2,2-ethylenebis(4,6-di-tert-butylphenyl)fluorophosphite.

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

[0032] In a preferred embodiment of the present invention, the LLDPE composition of the present invention comprises the following components: only LLDPE resin, the inorganic particle / rubber particle composite and other additives are blended. The mass content of LLDPE in the LLDPE composition is 96-99%, the mass content of the inorganic particle / rubber particle composite is 0.5-3%, and the mass content of other additives is 0.5-1.0%, which is very suitable for use as a raw material for mulch film production.

[0033] Compared with the prior art, which solves the problem of uneven winding by adding a certain amount of LDPE or HDPE to the LLDPE raw material or reducing the blowing ratio, the present invention provides a solution of a composition prepared by blending only one LLDPE resin raw material, an inorganic particle / rubber particle composite and an optional processing aid. The problem of uneven winding in the production process of ground film caused by existing raw materials (especially under high blowing ratio (>2.7)) is solved. After the inorganic particle / rubber particle composite formed by the radiation cross-linked rubber particles covering the surface of the inorganic particles is blended with LLDPE, the interaction between the inorganic particles and the LLDPE interface is improved. At the same time, after the rubber particles are irradiated and cross-linked, the rubber particles no longer adhere to each other, so the viscosity between the films can be reduced, thereby improving the extrusion blowing process and making the film winding more neat, which not only reduces the generation of waste film and improves production efficiency, but also saves the LLDPE, LDPE or HDPE resin compounding production link, simplifies the process flow and reduces production costs.

[0034] Uneven rolling means that the misalignment width of the ground film roll is greater than 30mm or the film roll has ribs.

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

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

[0037] During the preparation process, the blending temperature of the materials corresponds to the usual processing temperature of the matrix resin LLDPE, and should be selected within the range that ensures that the matrix resin is completely melted and does not decompose. In addition, according to processing requirements, conventional additives for plastic processing, such as antistatic agents, lubricants, slip agents, etc., can be added to the blended materials in appropriate amounts. During the blending process, the components can be added to the melt blending equipment at the same time by metering or the like to be melt blended; or the components can be pre-mixed uniformly by a general mixing equipment, and then melt blended and extruded once through a rubber-plastic blending equipment to obtain a modified resin composition.

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

[0039] The third aspect of the present invention is to provide an LLDPE film, wherein the material of the LLDPE film is an LLDPE composition, and the LLDPE composition is the LLDPE composition described in the first aspect or the composition prepared by the preparation method described in the second aspect; preferably, the blowing ratio is greater than 2.7.

[0040] The fourth aspect of the present invention is to provide a method for preparing the LLDPE film described in the third aspect, comprising forming the LLDPE composition described in the first aspect or the LLDPE composition prepared by the preparation method described in the second aspect by a blow molding method to obtain the LLDPE film, preferably, the blow-up ratio is greater than 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 ground film or a wrapping film.

[0042] As mentioned above, in order to improve the problem of uneven winding, three methods are generally adopted: (1) adding a certain amount of LDPE or HDPE to the LLDPE raw material to improve the processing performance, (2) reducing the blow-up ratio, and (3) aligning the two ends of the film roll. Although these three methods can solve or improve the problem of uneven winding in the production of mulch films, they also create new difficulties: blending with LDPE or HDPE is not suitable for online addition by resin manufacturers because the addition amount is large (more than 5wt%), and can only be produced by post-mixing, 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 lateral tensile load and right-angle tearing load of the mulch film are also reduced accordingly.

[0043] The inventors unexpectedly discovered during the research process that after blending the specific inorganic particle / rubber particle composite of the present invention with LLDPE, the viscosity between films can be reduced and the extrusion blowing process can be improved. In particular, the film can be rolled more neatly, which solves the technical problem that the existing LLDPE needs to add other components (LDPE or HDPE) to improve the processing performance of blow-molded ultra-thin films. The present invention can be smoothly processed and molded using a single homogeneous LLDPE.

[0044] It has been verified that, during the processing of the nominally 10-micron thick ground film of the present invention, the dislocation width of the film roll is greatly reduced, there is no bursting, and the tensile load, nominal strain at break and right-angle tearing performance are all improved, achieving the dual purpose of improving the resin processing performance while improving the mechanical properties.

[0045] The present invention can improve the extrusion blowing process and make the film winding more neat, which not only reduces the generation of waste film and improves production efficiency, but also saves the LLDPE, LDPE or HDPE resin compounding production link, simplifies the process flow and reduces production costs. DETAILED DESCRIPTION

[0046] The present invention is described in detail below in conjunction with specific embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the contents of the present invention still fall within the scope of protection of the present invention.

[0047] The present invention will be further described below in conjunction with embodiments. The described embodiments are only possible technical implementations of the present invention, and are not all possible implementations. Those skilled in the art can fully combine the embodiments of the present invention to obtain other embodiments without creative work, and these embodiments are also within the scope of protection of the present invention. The scope of the claims of the present invention is not limited by these embodiments, and the scope of the claims of the present invention is set forth in the attached claims.

[0048] The experimental data in the examples were measured using the following equipment and methods:

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

[0050] The right-angle tearing load is carried out in accordance with the national standard GB / T1130-1991 and the Xinjiang Uygur Autonomous Region local standard DB653189-2014. A single specimen is used, the initial marking distance between the fixtures is 55mm, and the test speed (no load) is 200mm / min. The arithmetic mean of the experimental results is taken.

[0051] The melt index test temperature is 190±5℃ and the load is 2.16kg.

[0052] The film roll offset width is a quantitative parameter that quantitatively describes the uniformity of film roll winding. Single-layer winding refers to the difference between the width of the ground film roll and the nominal width of the film, and double-layer winding refers to the difference between the width of the film roll and the folded diameter width of the film.

[0053] Uneven rolling means that the misalignment width of the ground film roll is greater than 30mm or the film roll has ribs.

[0054] The preparation process of the inorganic particle / rubber particle composite is referred to patent CN1239587C. The parameters of calcium carbonate, rubber latex and proportions in the present invention are recorded in each embodiment.

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

[0056] The process of initial mixing and melt blending of materials is as follows: first weigh all materials according to the proportion, perform preliminary mixing in a high-speed mixer for 20 seconds, and then use a twin-screw extruder (Coperion (Nanjing) Machinery Co., Ltd., aspect ratio 30:1, screw diameter 30 mm) for melt blending and granulation, the speed is 200r / min, the temperature is set to 170℃, 180℃, 190℃, 200℃, 200℃, 200℃, and the feed amount is 14; the obtained pellets are placed in a tray and treated in an oven at 70℃ for 4 hours to remove moisture.

[0057] The ground film is prepared by a double-layer blow molding method. The film blowing machine is a German Colin. The temperature settings of the film blowing machine are: the temperature of each section is set at 160℃, 180℃, 200℃, 210℃, 210℃, 210℃, 210℃, the screw speed is 40r / min, the film blowing width is 31.0cm, the nominal thickness is 10.0μm, and the blowing ratio is 3.0.

[0058] Embodiment 1:

[0059] Weigh the LLDPE resin powder (Chemical Branch of Zhongtian Hechuang Energy Co., Ltd., melt index: 1.0g / 10min, density: 0.918g / cm 3 ) 2000g, primary antioxidant 1010 (Yingkou Fengguang New Materials Co., Ltd.) 1.0g, auxiliary antioxidant 168 (Yingkou Fengguang New Materials Co., Ltd.) 1.2g, hindered amine light stabilizer 944 (Beijing Tiangang Auxiliary Co., Ltd.) 6.0g, calcium carbonate / styrene-butadiene rubber composite particles (prepared by Beijing Institute of Chemical Industry, calcium carbonate: styrene-butadiene rubber particle mass ratio is 80:20; calcium carbonate: Lingshou County Guanghui Mineral Products Processing Co., Ltd., mesh number 1000; styrene-butadiene rubber latex, Yanshan Petrochemical High-tech Co., Ltd.) 10.0g, after being evenly dispersed by a high-speed mixer, melt blended and granulated by a twin-screw. Blown mulch: nominal thickness 10.0μm, blowing ratio 3.0. Test the longitudinal / transverse tensile load, nominal strain at break and right-angle tear load of the mulch, as well as the dislocation width of the film roll and the number of burst ribs.

[0060] Embodiment 2:

[0061] Weigh the LLDPE resin powder (Chemical Branch of Zhongtian Hechuang Energy Co., Ltd., melt index: 1.0g / 10min, density: 0.918g / cm 3) 2000g, primary antioxidant 1010 (Yingkou Fengguang New Materials Co., Ltd.) 1.0g, auxiliary antioxidant 168 (Yingkou Fengguang New Materials Co., Ltd.) 1.2g, hindered amine light stabilizer 944 (Beijing Tiangang Auxiliary Co., Ltd.) 6.0g, calcium carbonate / styrene-butadiene rubber composite particles (prepared by Beijing Institute of Chemical Industry, calcium carbonate: styrene-butadiene rubber particle mass ratio is 80:20, calcium carbonate: Lingshou County Guanghui Mineral Products Processing Co., Ltd., mesh number 2000; styrene-butadiene rubber latex, Yanshan Petrochemical High-tech Co., Ltd.) 16.0g, after being dispersed evenly by a high-speed mixer, melt blended and granulated by a twin-screw extruder. Blown mulch: nominal thickness 10.0μm, blowing ratio 3.0. Test the longitudinal / transverse tensile load, nominal strain at break and right-angle tear load of the mulch, as well as the dislocation width of the film roll and the number of burst ribs.

[0062] Embodiment 3:

[0063] Weigh the LLDPE resin powder (Chemical Branch of Zhongtian Hechuang Energy Co., Ltd., melt index: 1.0g / 10min, density: 0.918g / cm 3 ) 2000g, main antioxidant 1010 (Yingkou Fengguang New Materials Co., Ltd.) 1.0g, auxiliary antioxidant 168 (Yingkou Fengguang New Materials Co., Ltd.) 1.2g, hindered amine light stabilizer 944 (Beijing Tiangang Auxiliary Co., Ltd.) 6.0g, calcium carbonate / styrene-butadiene rubber composite particles (prepared by Beijing Institute of Chemical Industry, calcium carbonate: styrene-butadiene rubber particle mass ratio is 70:30, calcium carbonate: Lingshou County Guanghui Mineral Products Processing Co., Ltd., mesh number 3000; styrene-butadiene rubber latex, Yanshan Petrochemical High-tech Co., Ltd.) 20.0g, after being evenly dispersed by a high-speed mixer, melt blended and granulated by a twin-screw extruder. Blown mulch: nominal thickness 10.0μm, blowing ratio 3.0. Test the longitudinal / transverse tensile load, nominal strain at break and right-angle tear load of the mulch, as well as the dislocation width of the film roll and the number of burst ribs.

[0064] Embodiment 4:

[0065] Weigh the LLDPE resin powder (Chemical Branch of Zhongtian Hechuang Energy Co., Ltd., melt index: 1.0g / 10min, density: 0.918g / cm 3) 2000 g of LLDPE resin powder (Chemical Branch of Zhongtian Hechuang Energy Co., Ltd., melt index: 1.0 g / 10 min, density: 0.918 g / cm³), 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 Tian Gang Auxiliary Agents Co., Ltd.), 20.0 g of talc powder / styrene-butadiene rubber composite particles (prepared by Beijing Research Institute of Chemical Industry, mass ratio of talc powder to styrene-butadiene rubber particles is 60:40, where talc powder: Guangxi Longguang Talc Development Co., Ltd., mesh number 2000; styrene-butadiene rubber latex, Yanshan Petrochemical High-Tech Co., Ltd.). After being dispersed evenly by a high-speed mixer, it is melt-blended and pelletized through a twin-screw extruder. The blown plastic film for mulch: nominal thickness 10.0 μm, blow-up ratio 3.0. Test the longitudinal / transverse tensile load, breaking nominal strain, right-angle tear load of the plastic film for mulch, as well as the width of film roll misalignment and the number of burst ribs.

[0066] Example 5:

[0067] Weigh LLDPE resin powder (Chemical Branch of Zhongtian Hechuang Energy Co., Ltd., melt index: 1.0 g / 10 min, density: 0.918 g / cm 3 ) 2000 g of LLDPE resin powder (Chemical Branch of Zhongtian Hechuang Energy Co., Ltd., melt index: 1.0 g / 10 min, density: 0.918 g / cm³), 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 Tian Gang Auxiliary Agents Co., Ltd.), 20.0 g of talc powder / polyethylene-vinyl acetate rubber composite particles (prepared by Beijing Research Institute of Chemical Industry, mass ratio of talc powder to polyethylene-vinyl acetate rubber particles is 70:30, where talc powder: Guangxi Longguang Talc Development Co., Ltd., mesh number 2000; polyethylene-vinyl acetate rubber latex, Yanshan Petrochemical High-Tech Co., Ltd.). After being dispersed evenly by a high-speed mixer, it is melt-blended and pelletized through a twin-screw extruder. The blown plastic film for mulch: nominal thickness 10 μm, blow-up ratio 3.0. Test the longitudinal / transverse tensile load, breaking nominal strain, right-angle tear load of the plastic film for mulch, as well as the width of film roll misalignment and the number of burst ribs.

[0068] Example 6:

[0069] Weigh LLDPE resin powder (Chemical Branch of Zhongtian Hechuang Energy Co., Ltd., melt index: 1.0 g / 10 min, density: 0.918 g / cm 3) 2000g, main antioxidant 1010 (Yingkou Fengguang New Materials Co., Ltd.) 1.0g, auxiliary antioxidant 168 (Yingkou Fengguang New Materials Co., Ltd.) 1.2g, hindered amine light stabilizer 944 (Beijing Tiangang Auxiliary Co., Ltd.) 6.0g, calcium carbonate / polyethylene-vinyl acetate rubber particle composite (prepared by Beijing Chemical Research Institute, calcium carbonate: polyethylene-vinyl acetate rubber particle mass ratio is 70:30, calcium carbonate: Lingshou County Guanghui Mineral Products Processing Co., Ltd., mesh number 2000; polyethylene-vinyl acetate rubber latex, Yanshan Petrochemical High-tech Co., Ltd.) 20.0g, after being evenly dispersed by a high-speed mixer, melt blended and granulated by a twin-screw. Blown mulch: nominal thickness 10.0μm, blowing ratio 3.0. Test the longitudinal / transverse tensile load, nominal strain at break and right-angle tear load of the mulch, as well as the dislocation width of the film roll and the number of burst ribs.

[0070] Comparative Example 1:

[0071] Weigh the LLDPE resin powder (Chemical Branch of Zhongtian Hechuang Energy Co., Ltd., melt index: 1.0g / 10min, density: 0.918g / cm 3 ) 2000g, primary antioxidant 1010 (Yingkou Fengguang New Materials Co., Ltd.) 1.0g, auxiliary antioxidant 168 (Yingkou Fengguang New Materials Co., Ltd.) 1.2g, hindered amine light stabilizer 944 (Beijing Tiangang Auxiliary Co., Ltd.) 6.0g, after being evenly dispersed by a high-speed mixer, melt blended and granulated by a twin-screw. Blown mulch: nominal thickness 10.0μm, blow-up ratio 3.0, and the blown film is unstable. Test the longitudinal / transverse tensile load, nominal strain at break and right-angle tear load of the mulch, as well as the film roll dislocation width and the number of ribs.

[0072] Comparative Example 2:

[0073] Weigh the LLDPE resin powder (Chemical Branch of Zhongtian Hechuang Energy Co., Ltd., melt index: 1.0g / 10min, density: 0.918g / cm 3 ) 2000g, primary antioxidant 1010 (Yingkou Fengguang New Materials Co., Ltd.) 1.0g, secondary antioxidant 168 (Yingkou Fengguang New Materials Co., Ltd.) 1.2g, hindered amine light stabilizer 944 (Beijing Tiangang Auxiliary Co., Ltd.) 16.0g, calcium carbonate (Lingshou County Guanghui Mineral Products Processing Co., Ltd., mesh number 2000) 10.0g are dispersed evenly by a high-speed mixer, melt blended and granulated by a twin-screw. Blown mulch: nominal thickness 10.0μm, blowing ratio 3.0. Blown mulch: nominal thickness 10.0μm, blowing ratio 3.0. Test the longitudinal / transverse tensile load, nominal strain at break and right-angle tear load of the mulch, as well as the dislocation width of the film roll and the number of burst ribs.

[0074] Comparative Example 3

[0075] The ground film was prepared according to the method of Example 6, except that the 2000 mesh calcium carbonate was replaced with 200 mesh calcium carbonate, and the rest remained unchanged. The average particle size of calcium carbonate was 74 microns. Under high blow-up ratio conditions, when blowing a film of about 10 microns, the primary calcium carbonate particles were too large. After the film melt came out of the die, melt fracture occurred during traction cooling, resulting in film breakage and film breaking, and production difficulties. The remaining film samples were taken for mechanical property testing, and the results are shown in the following table.

[0076] Table 1 Physical and mechanical properties test and film blowing process status of nominal 10 μm thick ground film prepared using the LLDPE composition of the present invention as raw material

[0077]

[0078] As can be seen from Table 1, the tensile load, nominal strain at break, right-angle tearing performance, film roll dislocation width, and number of ribs of Examples 1-6 are significantly better than those of Comparative Examples 1-3, achieving the dual purpose of improving mechanical properties while improving resin processing performance.

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

[0080] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to 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 words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

[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 conventionally understood by those skilled in the art. In the event of a conflict, the definition in this specification shall prevail.

[0082] When this specification uses the prefix "well-known to those skilled in the art", "prior art" or similar terms to introduce materials, substances, methods, steps, devices or components, etc., the objects introduced by the prefix cover those conventionally used in the art when the present invention was proposed, but also include those that are not commonly used at present but will become recognized in the art as being suitable for similar purposes.

[0083] The endpoints and any values ​​of the ranges disclosed in the present invention document are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in this article. Hereinafter, in principle, each technical solution can be combined with each other to obtain a new technical solution, which should also be regarded as specifically disclosed in this article.

[0084] In the context of the present specification, any matters or items not mentioned are directly applicable to those known in the art without any changes except those explicitly stated.

[0085] Moreover, any embodiment described in this document may be freely combined with one or more other embodiments described in this document, and the technical solutions or technical ideas formed thereby are deemed to be part of the original disclosure or original record of the present invention, and should not be regarded as new content that has not been disclosed or anticipated in this document, unless a person skilled in the art considers that the combination is obviously unreasonable.

Claims

1. A LLDPE composition comprising an LLDPE resin, an inorganic particle / rubber particle composite and an optional additive; in, The inorganic particle / rubber particle composite contains inorganic particles and rubber particles covering the surface of the inorganic particles. The mesh size of the inorganic particles is 800-4000 mesh, preferably 1500-3500 mesh, and more preferably 1500-3000 mesh. The rubber particles are rubber particles with a cross-linked structure.

2. The LLDPE composition according to claim 1, Features: The content of inorganic particles in the inorganic particle / rubber particle composite is 50-80wt%, preferably 60-80wt%; and / or, The inorganic particles are selected from at least one of calcium carbonate, talc, montmorillonite, kaolin, titanium dioxide and silicon dioxide, preferably at least one of calcium carbonate, talc and silicon dioxide, most preferably calcium carbonate; and / or, The inorganic particles may have the same or different particle shapes, preferably, a single particle may be spherical, elliptical, blocky, flake-shaped or irregular in shape; and / or, The smallest dimension of the three dimensions of the inorganic particles is not less than 1.0 micrometer, more preferably not less than 2.0 micrometer.

3. The LLDPE composition according to claim 1, Features: 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, acrylic rubber particles, ethylene-vinyl acetate copolymer particles, isoprene rubber particles, and acrylic acid-butadiene particles; preferably selected from at least one of styrene-butadiene rubber particles, carboxylated styrene-butadiene rubber particles, and ethylene-vinyl acetate copolymer particles; and / or, The rubber particles have a gel content of 75% by weight or more, preferably 85% by weight or more; and / or, The average particle size of the rubber particles is 20 to 500 nm, preferably 30 to 200 nm; and / or, The rubber particles are of a homogeneous structure.

4. The LLDPE composition according to claim 1, Features: The LLDPE resin is copolymerized with ethylene and α-olefin, wherein the α-olefin is preferably selected from at least one of butene-1, hexene-1 and octene-1; preferably, At 190±5°C and a load of 2.16 kg, the melt flow rate of the LLDPE resin is 0.3 to 3.0 g / 10 min, preferably 0.5 to 2.5 g / 10 min; preferably, The LLDPE composition contains only one resin raw material, which is LLDPE resin.

5. The LLDPE composition according to claim 1, Features: The LLDPE composition contains an auxiliary agent; preferably, The auxiliary agent includes one or more of a primary antioxidant, a secondary antioxidant, a light stabilizer, an ultraviolet absorber, an antistatic agent, and a lubricant.

6. The LLDPE composition according to claim 1, Features: The auxiliary agent includes a light stabilizer; preferably, In the LLDPE composition, the amount of the light stabilizer is 0.1-1 part, preferably 0.2-0.8 part, relative to 100 parts of LLDPE resin, by mass; and / or, The light stabilizer is one or more of a hindered amine light stabilizer and an ultraviolet absorber. 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.

7. The LLDPE composition according to claim 1, Features: The auxiliary agent includes a primary antioxidant and a secondary antioxidant; and / or, In parts by mass, in the LLDPE composition, relative to 100 parts of LLDPE resin, the amount of the primary antioxidant is 0.02-0.1 parts, preferably 0.03-0.06 parts; the amount of the secondary antioxidant is 0.02-0.15 parts, preferably 0.03-0.1 parts; Preferably, the primary antioxidant is a hindered phenol antioxidant, preferably at least one selected from pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 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, 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; and / or, Preferably, the auxiliary antioxidant is selected from phosphites and / or thioester antioxidants, preferably selected from phosphites, including at least one of tris(nonylphenyl)phosphite, tris(2,4-di-tert-butylphenyl)phosphite, bis(octadecyl)pentaerythritol diphosphite, pentaerythritol bis(diphosphite (2,4-tert-butylphenyl) ester, bis(2,6-di-tert-butyl-4-tolyl)pentaerythritol phosphite, tetrakis(2,4-di-tert-butyloctaalkoxy-4,4'-biphenyl)phosphate, and 2,2-ethylenebis(4,6-di-tert-butylphenyl)fluorophosphite.

8. The LLDPE composition according to any one of claims 1 to 7, Features: In the LLDPE composition, the content of the inorganic particle / rubber particle composite is 0.3-3 parts, preferably 0.5-2 parts, relative to 100 parts of LLDPE resin, by mass.

9. A method for preparing the LLDPE composition according to any one of claims 1 to 8, comprising the step of melt-mixing raw materials including the LLDPE resin, the inorganic particle / rubber particle composite and optional additives; preferably, Firstly, raw materials including LLDPE resin, inorganic particle / rubber particle composite and optional auxiliary agent are premixed to obtain a premixed composition; and then the premixed composition is melt-blended to obtain the LLDPE composition.

10. An LLDPE film, wherein the material of the LLDPE film is an LLDPE composition, and the LLDPE composition is the LLDPE composition according to any one of claims 1 to 8 or the composition prepared by the preparation method according to claim 9.

11. A method for preparing the LLDPE film according to claim 10, comprising forming the LLDPE composition according to any one of claims 1 to 8 or the LLDPE composition prepared by the preparation method according to claim 9 by a blow molding method to obtain the LLDPE film; preferably, the blow-up ratio is greater than 2.

7.

12. Use of the LLDPE film according to claim 10 or the LLDPE film obtained by the preparation method according to claim 11 as ground film or wrapping film.

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