Acid-resistant polyethylene composition, film as well as preparation method and application of film

Abstract

The invention relates to an acid-resistant polyethylene composition, a film and a preparation method and application thereof, the acid-resistant polyethylene composition comprises a resin matrix and an antioxidant, and further comprises 0.5-5 parts of hydrotalcite, 0.5-3 parts of a light stabilizer and an optional nucleating auxiliary agent, based on 1000 parts of the resin matrix by weight, the content of the hydrotalcite is 0.5-5 parts, the content of the light stabilizer is 0.5-3 parts, and the content of the nucleating auxiliary agent is 0.5-3 parts. The average particle size of the hydrotalcite is 100 to 800 nm. After the acid-resistant film is subjected to acid treatment and artificial ultraviolet aging, the mechanical property retention rate reaches 90% and is far higher than that of a common agricultural film, and the acid-resistant film can be widely applied to mechanical recovery and has important significance in improving the agricultural film recovery rate and establishing a green recoverable technology.

Description

Technical Field

[0001] The present invention relates to the field of agricultural films, and more particularly to an acid-resistant polyethylene film and a preparation method and application thereof. Background Art

[0002] Agricultural film is an important agricultural production material. The promotion and application of agricultural film has also promoted the rapid development of agriculture. Ordinary polymer plastic materials are difficult to degrade naturally. At a certain stage, they will affect the soil quality and ecological environment and cause environmental pollution. For this reason, many departments in my country have promptly introduced relevant policies and measures for agricultural film, encouraged technological innovation, developed high-end agricultural film enterprises, and established a waste agricultural film recycling system. According to statistics from the Agricultural Film Committee of the China Plastics Processing Industry Association, "the average growth rate of the agricultural film industry is 3%, and by 2026, the output of agricultural plastic film in my country may reach more than one million tons.

[0003] Such large-scale use of agricultural film has both advantages and disadvantages. On the one hand, it plays a huge role in improving agricultural quality and efficiency, but on the other hand, it also causes serious harm to the soil environment. Abandoned agricultural film fragments enter the cultivated soil, affecting the permeability of the soil, reducing the soil moisture content, weakening the drought resistance, causing secondary salinization, causing soil compaction and reduced fertility, hindering the absorption of water by crops and root growth, and gradually deteriorating the quality of cultivated land, causing serious damage to the agricultural ecological environment. The residual film is abandoned in the fields and blown by the wind to the front and back of houses, treetops in the fields, and river ponds, affecting the appearance of the village. How to keep the film thickness basically unchanged, but maintain its mechanical properties after use, so as to improve the film recovery rate and reduce "white pollution" has become an important problem that needs to be solved urgently.

[0004] In the existing agricultural film technology, in order to improve the film recovery rate, hindered amine light stabilizers are usually used to modify the matrix to improve the strength of the film material after use and improve the recovery rate. However, during the use of agricultural films, they will come into contact with a large amount of sulfur-containing and chlorine-containing pesticides. When pesticides come into contact with water, acidic hydrochloric acid and sulfurous acid will be generated. They react with alkaline hindered amine light stabilizers, which will reduce the effect of the light stabilizer, reduce the performance of the resin matrix, and lose some of the mechanical properties of the material, resulting in a low recovery rate of agricultural films after use. In particular, for crops such as watermelons and flowers that are sprayed with more pesticides, as well as greenhouse films used in areas affected by acid rain, there is a high demand for acid-resistant agricultural films.

[0005] Therefore, the present invention provides an acid-resistant high-recycling film and a preparation method thereof. After acid treatment and artificial ultraviolet aging, the mechanical property retention rate reaches 90%, which is higher than that of ordinary agricultural films. It can be widely used in mechanical recycling, which is of great significance for improving the recycling rate of agricultural films and establishing green recyclable technology. Summary of the invention

[0006] In order to achieve the above-mentioned purpose of the invention, the present invention provides an acid-resistant polyethylene composition, a film, a preparation method and application thereof. The acid-resistant polyethylene composition of the present invention can maintain the mechanical properties of the material after aging. The acid-resistant polyethylene composition of the present invention can maintain the mechanical properties of the material after aging. After acid treatment and artificial ultraviolet aging, the mechanical property retention rate reaches 90%, which is basically equivalent to that before use. It has very good acid resistance, which is much higher than that of ordinary agricultural films, can increase the service life of the film, and can be widely used in mechanical recycling. It is of great significance to improve the recycling rate of agricultural films and establish green recyclable technology.

[0007] The first aspect of the present invention is to provide a polyethylene composition, comprising a polyethylene resin matrix, an antioxidant, an optional nucleating aid, hydrotalcite and a light stabilizer. In parts by mass, relative to 1000 parts of polyethylene, the content of hydrotalcite in the polyethylene composition is 0.5 to 5 parts, the content of the light stabilizer is 0.5 to 3 parts, and the average particle size of the hydrotalcite is 100-800nm.

[0008] According to the present invention, the light stabilizer can be selected in a wide range. In a preferred embodiment of the present invention, the light stabilizer is selected from at least one of salicylate light stabilizers, benzoate light stabilizers, benzophenone light stabilizers, benzotriazole light stabilizers, triazine light stabilizers, substituted acrylonitrile light stabilizers, oxamide light stabilizers, organic nickel complex light stabilizers, and hindered amine light stabilizers, including but not limited to sebacate bis-2,2,6,6-tetramethylpiperidinol ester (hindered amine light stabilizer 770); poly{[6-[(1,1,3,3-tetramethylbutyl)amino]]-1 ,3,5-triazine-2,4-bis[(2,2,6,6,-tetramethyl-piperidinyl)imino]-1,6-hexanediamine[(2,2,6,6-tetramethyl-4-piperidinyl)imino]}(hindered amine light stabilizer 944); poly(4-hydroxy-2,2,6,6-tetramethyl-1-piperidinethanol) succinate (hindered amine light stabilizer 622); poly{(6-morpholinyl-5-triazine-2,4-diyl)(2,2,6,6-tetramethylpiperidinyl)iminohexamethylene[(2,2,6,6-tetramethylpiperidinyl)-imino]}(hindered amine light stabilizer 3346).

[0009] In a preferred embodiment of the present invention, the hydrotalcite has an intercalated structure, preferably at least one of Zn, Al and Mg elements is intercalated between the layers; most preferably, the hydrotalcite is hydrotalcite UV-02.

[0010] In a preferred embodiment of the present invention, the polyethylene resin matrix is ​​selected from linear low-density polyethylene; preferably, the linear low-density polyethylene is a copolymer of ethylene and α-olefin, and preferably the α-olefin is at least one of butene-1, hexene-1, and octene-1.

[0011] According to the present invention, the antioxidant can be selected from a wide range. In a preferred embodiment of the present invention, the antioxidant includes a primary antioxidant and a secondary antioxidant. More preferably,

[0012] The primary antioxidant is a hindered phenol antioxidant, and / or the secondary antioxidant is selected from at least one of phosphite and thioester antioxidants.

[0013] Preferably, the primary antioxidant is a hindered phenol, including but not limited to pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (antioxidant 1010), β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate octadecyl alcohol (antioxidant 1076), 1,3,5-trimethyl-2,4,6-(3,5-di-tert-butyl-4-hydroxybenzyl) benzene (antioxidant 1330), 1,3 , at least one of 5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanuric acid (antioxidant 3114), β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant 1135) and 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione (antioxidant 1790).

[0014] Preferably, the auxiliary antioxidant includes phosphites and thioesters, and preferably includes but is not limited to phosphites, including tris(nonylphenyl)phosphite (TNPP), tris(2,4-di-tert-butylphenyl)phosphite (antioxidant 168), bis(octadecyl)pentaerythritol diphosphite (antioxidant 618), pentaerythritol bis(2,4-tert-butylphenyl)diphosphite (antioxidant 626), bis(2,6-di-tert-butyl-4-tolyl)pentaerythritol phosphite (PEP-36), tetrakis(2,4-di-tert-butyloctaalkoxy-4,4'-biphenyl)phosphate, 2,2-ethylenebis(4,6-di-tert-butylphenyl)fluorophosphite (antioxidant 398), and the like.

[0015] In a preferred embodiment of the present invention, the content of the primary antioxidant in the polyethylene composition is 0.2 to 3 parts, preferably 0.2 to 2 parts, more preferably 0.2 to 1 part, relative to 1000 parts of polyethylene, by mass; the content of the secondary antioxidant is 0.3 to 3 parts, preferably 0.3 to 2 parts.

[0016] In a preferred embodiment of the present invention, the nucleating aid is selected from the following nucleating agents and / or the following nucleating agents and resin nucleating agents formed by rubber particles having a cross-linked structure: at least one of organic nucleating agents and inorganic nucleating agents, preferably at least one of organic carboxylic acid nucleating agents, organic carboxylate nucleating agents, and organic phosphate nucleating agents, and more preferably at least one of nucleating agent NA11, nucleating agent NA21, and nucleating agent 20E.

[0017] In a preferred embodiment of the present invention, the mass ratio of the crosslinked rubber particles in the resin nucleating agent to the nucleating agent is (3-7): (7-3).

[0018] In a preferred embodiment of the present invention, the content of the nucleating aid in the polyethylene composition is 0-0.8 parts by mass, preferably 0-0.5 parts, relative to 1000 parts of the polyethylene resin matrix.

[0019] In a preferred embodiment of the present invention, the rubber particles having a cross-linked structure have at least one of the following characteristics:

[0020] The rubber particles having a cross-linked structure are at least one of the following rubber particles having a cross-linked structure: natural rubber, styrene-butadiene rubber, carboxylated styrene-butadiene rubber, nitrile rubber, carboxylated nitrile rubber, chloroprene rubber, polybutadiene, acrylic rubber, styrene-butadiene rubber, isoprene rubber, butyl rubber, ethylene-propylene rubber, polysulfide rubber, acrylate-butadiene rubber, polyurethane rubber, fluororubber, ethylene-vinyl acetate rubber; and / or,

[0021] The average particle size of the rubber particles is 0.02 to 2 microns, preferably 0.1 to 1 micron, more preferably 0.2 to 0.5 micron; and / or,

[0022] The rubber particles are spherical; and / or,

[0023] The rubber particles have a gel content of 60 wt % or more, preferably 80 wt % or more.

[0024] The cross-linked rubber particles of the present invention can be prepared by the method of patent CN1402752, wherein a cross-linking agent such as TMPTA is added to a rubber latex containing uncross-linked rubber particles with a particle size of 20-2000 nm, the mixture is irradiated with a high-energy ray source, and spray-dried.

[0025] In the present invention, the nucleating agent and the rubber particles having a cross-linked structure can be added to the resin composition as raw materials separately, or commercial products containing both can be used. For example, in a more preferred embodiment of the present invention, the composite auxiliary agent is selected from at least one of VP101B, VP101C, and VP801E.

[0026] The second aspect of the present invention is to provide a method for preparing the polyethylene composition of the first aspect, comprising melt blending raw materials including the polyethylene resin matrix, the antioxidant, the hydrotalcite, the light stabilizer and the optional nucleating aid to obtain the polyethylene composition; preferably,

[0027] The steps include:

[0028] Step 1, premixing raw materials including the polyethylene resin matrix, the antioxidant, the hydrotalcite, the light stabilizer and the optional nucleating aid;

[0029] Step 2: melt-mix the pre-mixed mixture obtained in step 1 to obtain the polyethylene composition.

[0030] The method of the invention is simple and easy to implement, has universal applicability, and is easy to realize industrial production.

[0031] The resin composition of the present invention is prepared by melt blending the raw material components including the polyethylene resin matrix and the like in the conventional rubber and plastic blending equipment in a single step.

[0032] During the preparation process, the blending temperature of the materials corresponds to the usual processing temperature of the polyethylene resin matrix, and should be selected within the range that ensures that the polyethylene resin matrix is ​​completely melted and does not decompose. According to processing requirements, conventional additives for plastic processing 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 for melt blending; or the components can be pre-mixed uniformly by a general mixing equipment, and then melt blended and extruded once by a rubber-plastic blending equipment to obtain a modified resin composition.

[0033] 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 torque rheometer, etc. The material mixing equipment is selected from mechanical mixing equipment such as high-speed mixers and kneaders commonly used in the art.

[0034] The third aspect of the present invention is to provide a polyethylene film, wherein the material of the polyethylene film is the polyethylene composition described in the first aspect or the polyethylene composition prepared by the preparation method described in the second aspect;

[0035] Preferably, the polyethylene film is obtained by blow molding.

[0036] The fourth aspect of the present invention is to provide a method for preparing the polyethylene film described in the third aspect, comprising the step of blow molding the polyethylene composition described in the first aspect or the polyethylene composition obtained by the preparation method described in the second aspect.

[0037] The fifth aspect of the present invention is to provide an application of the polyethylene composition described in the first aspect or the polyethylene composition prepared by the preparation method described in the second aspect or the polyethylene film described in the third aspect or the polyethylene film prepared by the preparation method described in the fourth aspect in ground film and greenhouse film.

[0038] The advantages of the present invention are:

[0039] The polyethylene composition of the present invention contains a polyethylene resin matrix, an antioxidant, an optional nucleating aid, and also contains hydrotalcite and a light stabilizer. The above raw material types, the hydrotalcite with a specific average particle size, and the ratio of the hydrotalcite and the light stabilizer in the composition are used to obtain an acid-resistant polyethylene composition. The above components, especially the optional nucleating aid, also contain hydrotalcite and the light stabilizer to work synergistically. The acid-resistant polyethylene composition of the present invention can maintain the mechanical properties of the material after aging. After acid treatment and artificial ultraviolet aging, the mechanical property retention rate reaches 90%. It can be seen that the mechanical properties of the polyethylene composition film can be well maintained, which is basically equivalent to that before use. It has very good acid resistance, which is much higher than that of ordinary agricultural films, can increase the service life of the film, can be widely used in mechanical recycling, and is of great significance for improving the recycling rate of agricultural films and establishing green recyclable technology.

[0040] The acid-resistant agricultural film of the present invention does not frost or seep during processing and use; has light stability, thermal stability and chemical stability; is resistant to pesticide acid and is low in price, low in cost, easy to promote and use, and can be widely used in the agricultural field, such as greenhouse film and ground film. DETAILED DESCRIPTION

[0041] 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.

[0042] The scope of the present invention is not limited by these embodiments, but is set forth in the appended claims.

[0043] The experimental data in the examples were measured using the following equipment and methods:

[0044] The test of tensile load and nominal strain at break of specimen preparation was carried out in accordance with the national standard GB / T1040.3-2006. The specimen was 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 was stretched until it broke. The maximum tensile load was measured with an accuracy of 0.01 N. The prepared specimens clearly indicated the specimen number and sampling direction (horizontal or vertical).

[0045] The nominal strain at break is calculated as follows:

[0046] ε=ΔL / L×100

[0047] Where:

[0048] ε——nominal strain at fracture, %;

[0049] ΔL——Increment of the distance between fixtures, in millimeters (mm);

[0050] L——The initial distance between the fixtures, in millimeters (mm).

[0051] The test is carried out in accordance with QB / T1130-1991, with a single specimen test and an accuracy of 0.1N.

[0052] The material melt blending process is as follows: first weigh all the materials according to the proportion, perform preliminary mixing in a high-speed mixer for 20 seconds, and then use a twin-screw extruder to melt blend and granulate. The mixing equipment is a Coperion 35 twin-screw extruder with a speed of 200r / min and a temperature setting of 170°C, 180°C, 190°C, 200°C, 200°C, and 200°C; the obtained pellets are placed in a tray and treated in an oven at 70°C for 4 hours to remove moisture.

[0053] Film preparation: The film was prepared by blow molding. The equipment was a German Colin blown film machine. The temperatures of each section were set at 160°C, 180°C, 200°C, 210°C, 210°C, 210°C, 210°C. The feed amount was 25%, and the winding rate was 10m / min. The obtained film had a smooth surface, an average width of 22cm, and an average thickness of 10μm.

[0054] The prepared tensile specimens must first be treated with acid. The specimens are immersed in 0.1 mol / L sulfurous acid and hydrochloric acid for 24 hours respectively, and then taken out for artificial ultraviolet aging.

[0055] The prepared tensile specimens need to be subjected to artificial ultraviolet aging comparative experiments. The specific conditions of ultraviolet aging are as follows: refer to GB / T16422.3-2014, the light source is a fluorescent ultraviolet lamp, UV-A340 lamp tube, at a wavelength of 340nm, the irradiance is 0.76W / (m2 ·nm), and UV irradiation was carried out according to the rules of illumination temperature 60℃, radiation time 8h (bright); condensation temperature 50℃, condensation time 4h (dark), and the irradiation time was 240 hours.

[0056] In the following examples, 1076 produced by Yingkou Fengguang refers to antioxidant 1076.

[0057] The 168 produced by Yingkou Fengguang refers to antioxidant 168.

[0058] Hydrotalcite UV-02, Shandong Wanxin Weina Material Technology Co., Ltd., with an average particle size of 200 nm.

[0059] The nucleating agent Nap VP801 produced by Yanhua Hi-Tech contains the nucleating agent NA11 and polyethylene-ethyl acetate rubber particles with a cross-linked structure. The average particle size of the rubber particles is 0.2 microns, and the gel content of the rubber particles is 85wt%. The mass ratio of the rubber particles to the nucleating agent is 70:30.

[0060] Example 1-Example 4

[0061] 2000g of LLDPE resin ENG-34 provided by Zhongtian Hechuang was used as the matrix, and 0.5g1076, 1.36g168 and 1.0g calcium stearate produced by Yingkou Fengguang, 1g of light stabilizer 362 produced by Beijing Tiangang Chemical, and 1g of hydrotalcite UV-02 of Shandong Wanxin Weina Materials Technology Co., Ltd. were melt blended and film prepared according to the above conditions to prepare tensile and right-angle tearing specimens, which is Example 1. The sample of Example 1 was subjected to artificial ultraviolet accelerated aging to obtain Example 2. The sample of Example 1 was treated with hydrochloric acid and then subjected to artificial ultraviolet accelerated aging to obtain Example 3. The sample of Example 1 was treated with sulfurous acid and then subjected to artificial ultraviolet accelerated aging to obtain Example 4.

[0062] Example 5-Example 8

[0063] 2000g of LLDPE resin ENG-34 provided by Zhongtian Hechuang was used as a matrix, and melt blended and film prepared according to the above conditions were carried out with 0.5g1076, 1.36g168 and 1.0g calcium stearate produced by Yingkou Fengguang, 1g of light stabilizer 362 produced by Beijing Tiangang Chemical, 2g of hydrotalcite UV-02 produced by Shandong Wanxin Weina Materials Technology Co., Ltd., and 0.8g of nucleating agent Nap VP801 produced by Yanhua Hi-Tech to obtain tensile and right-angle tear specimens, which is Example 5.

[0064] After the sample of Example 5 was aged by artificial ultraviolet, it was Example 6. After the sample of Example 5 was treated with hydrochloric acid and then aged by artificial ultraviolet, it was Example 7. After the sample of Example 1 was treated with sulfurous acid and then aged by artificial ultraviolet, it was Example 8.

[0065] Example 9-Example 11

[0066] 2000g of LLDPE resin ENG-34 provided by Zhongtian Hechuang was used as the matrix, and melt blended and film prepared according to the above conditions with 0.5g1076, 1.36g 168 and 1.0g calcium stearate produced by Yingkou Fengguang, 1g light stabilizer 944 produced by Beijing Tiangang Chemical, and 2g hydrotalcite UV-02 produced by Shandong Wanxin Weina Material Technology Co., Ltd., to obtain a film with an average thickness of 40μm.

[0067] The sample of Example 9 was subjected to artificial ultraviolet accelerated aging to obtain Example 10. The sample of Example 9 was subjected to sulfurous acid treatment and then to artificial ultraviolet accelerated aging to obtain Example 11.

[0068] Comparative Example 1-Comparative Example 4

[0069] 2000g of LLDPE resin ENG-34 provided by Zhongtian Hechuang was used as the matrix, and 0.5g of 1076, 1.36g of 168 and 1.0g of calcium stearate produced by Yingkou Fengguang, and 1g of light stabilizer 362 produced by Beijing Tiangang Chemical were melt blended and film prepared according to the above conditions to prepare tensile and right-angle tearing specimens, which is Comparative Example 1. The sample of Comparative Example 1 was subjected to artificial ultraviolet accelerated aging to obtain Comparative Example 2. The sample of Comparative Example 1 was treated with hydrochloric acid and then subjected to artificial ultraviolet accelerated aging to obtain Comparative Example 3. The sample of Comparative Example 1 was treated with sulfurous acid and then subjected to artificial ultraviolet accelerated aging to obtain Comparative Example 4.

[0070] Comparative Example 5-Comparative Example 8

[0071] 2000g of LLDPE resin ENG-34 provided by Zhongtian Hechuang was used as the matrix, and 0.5g of 1076, 1.36g of 168 and 1.0g of calcium stearate produced by Yingkou Fengguang, and 4g of hydrotalcite UV-02 produced by Shandong Wanxin Weina Material Technology Co., Ltd. were melt blended and film prepared according to the above conditions to prepare Comparative Example 5. The sample of Comparative Example 5 was subjected to artificial ultraviolet accelerated aging to obtain Comparative Example 6. The sample of Comparative Example 5 was treated with hydrochloric acid and then subjected to artificial ultraviolet accelerated aging to obtain Comparative Example 7. The sample of Comparative Example 4 was treated with sulfurous acid and then subjected to artificial ultraviolet accelerated aging to obtain Comparative Example 8.

[0072] Comparative Examples 9-11

[0073] 2000g of LLDPE resin ENG-34 provided by Zhongtian Hechuang was used as the matrix, and 0.5g1076, 1.36g 168 and 1.0g calcium stearate produced by Yingkou Fengguang, and 2g of light stabilizer 625 produced by Beijing Tiangang Chemical were melt-blended and film prepared according to the above conditions to obtain a film with an average thickness of 40μm.

[0074] Light stabilizer 625 is produced by Tiangang Chemical and is currently the light stabilizer with the best acid resistance among the products on the market.

[0075] The sample of Comparative Example 9 was subjected to artificial ultraviolet accelerated aging to obtain Comparative Example 10. The sample of Comparative Example 9 was subjected to sulfurous acid treatment and then to artificial ultraviolet accelerated aging to obtain Comparative Example 11.

[0076] Table 1 Mechanical properties of film samples with a thickness of 10 μm

[0077]

[0078]

[0079] The above data show that this phenomenon is beneficial to maintaining the strength of the film in high heat and high UV environments, and is beneficial to increasing its service life and recycling rate.

[0080] From the data in the above table, it can be seen that comparative examples 1-4 are samples with only light stabilizer 362 added. Its aging resistance is acceptable. After aging for 240 hours, its transverse and longitudinal tensile loads and fracture strains remain basically unchanged. After being treated with dilute hydrochloric acid, the longitudinal tensile load is significantly reduced from 4.1N to 3.7N; after being treated with dilute sulfuric acid, the longitudinal tensile load of the sample is reduced from 4.1N to 3.54, a decrease of 14%. The light stabilizer 362 has a transverse and longitudinal performance retention rate of about 80% for the polyethylene matrix.

[0081] Comparative Examples 5-8 are samples that only add hydrotalcite UV blocking agent. From the test data, it can be seen that only adding hydrotalcite, for polyethylene film, the transverse and longitudinal tensile properties decreased by about 50%, and basically failed to protect the film. From the principle of polyolefin aging, although the use of hydrotalcite alone can reduce the number of initial free radicals, it does not have the function of absorbing free radicals. Therefore, when the number of free radicals accumulates to a certain extent, the aging of the matrix is ​​accelerated and the mechanical properties are significantly reduced.

[0082] Examples 1-4 are obtained by using hydrotalcite and light stabilizer in combination. As can be seen from the data in the above table, hydrotalcite and hindered amine light stabilizer can work together to reduce free radicals in the matrix at the early stage of aging. The two work together to maintain the mechanical properties of the material after aging. The polyethylene film of the present invention has strong resistance to dilute hydrochloric acid and dilute sulfuric acid. Therefore, the tensile property retention rates of Examples 3 and 4 after treatment with dilute hydrochloric acid and dilute sulfuric acid are both higher than 90%. It is about 10 percentage points higher than the commercially available product comparative examples 1-4.

[0083] Embodiments 5-8 are obtained by using hydrotalcite, nucleating agent and light stabilizer in combination. As can be seen from the data in the above table, the combined use of hydrotalcite, nucleating agent and light stabilizer can reduce the generation of free radicals in the early stage of aging, and absorb free radicals in the matrix to improve the strength of the matrix. The three work synergistically to maintain the mechanical properties of the material after aging. The tensile performance retention rates of Embodiments 7 and 8 after treatment with dilute hydrochloric acid and dilute sulfuric acid are both higher than 90%. It is about 10 percentage points higher than the commercially available product comparative examples 1-4. Whether before aging, after aging, after treatment with dilute hydrochloric acid, or after treatment with dilute sulfuric acid, the longitudinal tensile load of the material is higher than 4N, which is the best in the entire system.

[0084] The LLDPE resin in the above embodiment is replaced by other types of LLDPE resin, 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 1-8. It is found that the test results of the embodiment samples are similar to those of Examples 1-8, and are significantly better than the comparative examples.

[0085] Table 2 Mechanical properties of 40 μm thick films

[0086]

[0087] As shown in Table 2, in the film sample with a thickness of 40 μm, the mechanical properties of Example 9, which is a composite of 944 and hydrotalcite, are basically consistent with those of the comparative example after aging without acid treatment. After sulfuric acid treatment, the tensile load and fracture strain of the embodiment after aging are better than those of the corresponding comparative example product, showing excellent acid resistance.

[0088] During the use of ground film, the better the basic performance of the material and the higher the retention rate, the easier it is to recycle after use, which is conducive to the green recycling of ground film. The present invention adopts the method of using hydrotalcite in combination with a light stabilizer, or adding a nucleating agent, and uses hydrotalcite with primary light and heat stability as an acidic substance capture agent to protect the active nitrogen in the hindered amine light stabilizer from being eroded by acidic substances, give full play to the light and heat stabilization efficiency of the hindered amine, and maintain the strength of the film in high heat and high ultraviolet environments. It can be widely used in mechanical recycling, which is of great significance for improving the recycling rate of agricultural films and establishing green recyclable technology.

[0089] 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.

[0090] 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.

[0091] 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 commonly used in the art when this application is filed, but also include those that are not commonly used at present but will become recognized in the art as being suitable for similar purposes.

[0092] The endpoints and any values ​​of the scope disclosed in the present application document are not limited to the precise scope or value, and these scopes or values ​​should be understood to include values ​​close to these scopes or values. For numerical ranges, between the endpoint values ​​of each scope, between the endpoint values ​​of each scope and a separate point value, and between separate point values, one or more new numerical ranges can be combined with each other, and these numerical ranges should be considered 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 considered as specifically disclosed in this article.

[0093] 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.

[0094] 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 polyethylene composition contains a polyethylene resin matrix, an antioxidant, an optional nucleating agent, and further contains hydrotalcite and a light stabilizer. By mass, relative to 1000 parts of polyethylene, the content of hydrotalcite in the polyethylene composition is 0.5 - 5 parts, the content of the light stabilizer is 0.5 - 3 parts, and the average particle size of the hydrotalcite is 100 - 800 nm.

2. The polyethylene composition according to claim 1, wherein: the light stabilizer is selected from at least one of salicylate light stabilizers, benzoate light stabilizers, benzophenone light stabilizers, benzotriazole light stabilizers, triazine light stabilizers, substituted acrylonitrile light stabilizers, oxamide light stabilizers, organonickel complex light stabilizers, and hindered amine light stabilizers.

3. The polyethylene composition according to claim 1, wherein: the hydrotalcite has an intercalated structure, preferably at least one of Zn, Al, and Mg elements is intercalated between the layers; preferably, the hydrotalcite is hydrotalcite UV - 02.

4. The polyethylene composition according to claim 1, wherein: the polyethylene resin matrix is selected from linear low - density polyethylene; preferably, the linear low - density polyethylene is a copolymer obtained by copolymerizing ethylene with an α - olefin, and preferably the α - olefin is at least one of butene - 1, hexene - 1, and octene - 1.

5. The polyethylene composition according to claim 1, wherein: the antioxidant includes a primary antioxidant and a secondary antioxidant, preferably, the primary antioxidant is a hindered phenol antioxidant, and / or the secondary antioxidant is selected from at least one of phosphite antioxidants and thioester antioxidants; and / or, by mass, relative to 1000 parts of polyethylene, the content of the primary antioxidant in the polyethylene composition is 0.2 - 3 parts, preferably 0.2 - 2 parts, more preferably 0.2 - 1 part; the content of the secondary antioxidant is 0.3 - 3 parts, preferably 0.3 - 2 parts.

6. The polyethylene composition according to any one of claims 1 - 5, wherein: the nucleating agent is selected from the following nucleating agents and / or resin nucleating agents formed by the following nucleating agents and rubber particles with a cross - linked structure: at least one of organic nucleating agents and inorganic nucleating agents, preferably at least one of organic carboxylic acid nucleating agents, organic carboxylate nucleating agents, and organic phosphate nucleating agents, more preferably at least one of nucleating agent NA11, nucleating agent NA21, and nucleating agent 20E; preferably, the mass ratio of the cross - linked rubber particles to the nucleating agent in the resin nucleating agent is (3 - 7):(7 - 3); and / or, by mass, relative to 1000 parts of the polyethylene resin matrix, the content of the nucleating agent in the polyethylene composition, calculated by the mass of the nucleating agent, is 0 - 0.8 parts, preferably 0 - 0.5 parts.

7. The polyethylene composition according to claim 6, wherein: The rubber particles having a cross-linked structure are at least one of the following rubber particles having a cross-linked structure: natural rubber, styrene-butadiene rubber, carboxylated styrene-butadiene rubber, nitrile rubber, carboxylated nitrile rubber, chloroprene rubber, polybutadiene, acrylic rubber, styrene-butadiene rubber, isoprene rubber, butyl rubber, ethylene-propylene rubber, polysulfide rubber, acrylate-butadiene rubber, polyurethane rubber, fluororubber, ethylene-vinyl acetate rubber; and / or, The average particle size of the rubber particles is 0.02 to 2 microns, preferably 0.1 to 1 micron; and / or, The rubber particles are spherical; and / or, The rubber particles have a gel content of 60 wt % or more, preferably 80 wt % or more.

8. A method for preparing the polyethylene composition according to any one of claims 1 to 7, comprising melt blending raw materials including the polyethylene resin matrix, the antioxidant, the hydrotalcite, the light stabilizer and the optional nucleating aid to obtain the polyethylene composition; preferably, The steps include: Step 1, premixing raw materials including the polyethylene resin matrix, the antioxidant, the hydrotalcite, the light stabilizer and the optional nucleating aid; Step 2: melt-mixing the pre-mixed mixture obtained in step 1 to obtain the polyethylene composition.

9. A polyethylene film, wherein the polyethylene film is made of the polyethylene composition according to any one of claims 1 to 7 or the polyethylene composition prepared by the preparation method according to claim 8; Preferably, the polyethylene film is obtained by blow molding.

10. A method for preparing the polyethylene film according to claim 9, comprising the step of blow molding the polyethylene composition according to any one of claims 1 to 7 or the polyethylene composition obtained by the preparation method according to claim 8.

11. Use of the polyethylene composition according to any one of claims 1 to 7, or the polyethylene composition obtained by the preparation method according to claim 8, or the polyethylene film according to claim 9, or the polyethylene film obtained by the preparation method according to claim 10 in ground film and greenhouse film.

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