A high-temperature-resistant ethylene-vinyl alcohol copolymer, a preparation method and application thereof

Abstract

The application provides a high-temperature-resistant ethylene-vinyl alcohol copolymer, raw materials of the high-temperature-resistant ethylene-vinyl alcohol copolymer include, by weight percentage, 100 parts of a crosslinking point compound, 0.001-1 parts of an initiator, 5-80 parts of a high-temperature-resistant modifier, 100-500 parts of polyethylene and 1000-60000 parts of an ethylene-vinyl alcohol copolymer. The initiator initiates the grafting of the crosslinking point compound into the polyethylene molecular chain, and the mixture with the high-temperature-resistant modifier produces a synergistic effect, which can obviously improve the temperature resistance grade of the ethylene-vinyl alcohol copolymer, and the mechanical properties of the ethylene-vinyl alcohol copolymer do not change obviously under the high-temperature hot air aging test condition of 200 DEG C for 72 hours. Meanwhile, the product has higher tensile strength, excellent aging resistance and high-temperature resistance.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a high-temperature resistant ethylene-vinyl alcohol copolymer, its preparation method, and its application. Background Technology

[0002] Ethylene-vinyl alcohol copolymer (EVOH) is a functional polymer obtained by hydrolysis / alcoholization of ethylene-vinyl acetate copolymer (EVA). Due to its unique chemical structure, EVOH possesses excellent film-forming properties, barrier properties, thermal stability, and good processability.

[0003] CN106459548A discloses a resin composition particle containing specific amounts of ethylene-vinyl alcohol resin (A), polyamide (B), and lower fatty acid magnesium salt (C). Polyamide resin (B) is dispersed in the ethylene-vinyl alcohol resin (A) with an average dispersed particle size of less than 1 μm, as observed using an electron microscope. Lower fatty acid magnesium salt (C) is dispersed in both the ethylene-vinyl alcohol resin (A) and the polyamide resin (B). This results in a resin composition particle with excellent color tone. Furthermore, a film exhibiting excellent thermal stability during film formation, superior appearance immediately after film formation, and excellent appearance after heat treatment can be obtained. However, its high-temperature resistance is poor; CN1056509A discloses a composition consisting of a copolymer of ethylene and vinyl alcohol, 0.01% to 0.5% by weight of a monovalent or divalent metal salt of an aliphatic carboxylic acid having 3 to 9 carbon atoms, and 0.05% to 0.5% by weight of a hindered phenolic antioxidant, which has improved stability against the formation of oxidative gel at high temperatures; however, its high-temperature resistance is poor.

[0004] Currently, 80% of barrier films on the market contain EVOH, which is usually used in multilayer composites with polyethylene films. However, due to the structure of EVOH, this material has poor temperature resistance, and there is an urgent need to develop a high-temperature resistant EVOH product to meet its application requirements. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a high-temperature resistant ethylene-vinyl alcohol copolymer, its preparation method, and its application. By initiating the grafting of crosslinking point compounds into the polyethylene molecular chain through an initiator, and then combining it with a high-temperature resistant modifier to produce a synergistic effect, the high-temperature resistance of EVOH is ultimately improved.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a high-temperature resistant ethylene-vinyl alcohol copolymer, wherein the raw materials for preparing the high-temperature resistant ethylene-vinyl alcohol copolymer include, by weight: 100 parts of crosslinking point compound, 0.001-1 parts of initiator, 5-80 parts of high-temperature resistant modifier, 100-500 parts of polyethylene, and 1000-60000 parts of ethylene-vinyl alcohol copolymer.

[0008] In this invention, an initiator is used to initiate the grafting of crosslinking point compounds into the polyethylene molecular chain, and then a synergistic effect is generated through combination with a high-temperature resistant modifier, ultimately improving the high-temperature resistance of EVOH.

[0009] This invention grafts a crosslinking point compound into the polyethylene molecular chain, thereby enhancing the material's high-temperature resistance by forming a slight crosslink with EVOH at high temperatures. Simultaneously, a high-temperature resistant modifier is blended with the grafted polyethylene. Because the incorporation of the perfluoropolyether high-temperature resistant modifier creates a "shielding" and "barrier" effect on the overall material, the combination with the slightly crosslinked polyethylene further enhances the high-temperature resistance of EVOH without affecting its original high barrier and adhesive properties.

[0010] Perfluoropolyether is a polymer with a low molecular weight. Due to the large number of fluorine-containing and ether-containing structural units in its molecular chain, this material has excellent high-temperature resistance. When perfluoropolyether is blended with slightly cross-linked polyethylene, it can easily enter the voids of slightly cross-linked polyethylene to form a coating structure, which provides a good barrier against external high temperatures, thus forming a synergistic high-temperature resistance effect.

[0011] In this invention, "high temperature resistance" refers to a heat resistance temperature above 180℃, such as 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific values ​​included in the range.

[0012] The initiator is 0.001-1 parts by weight, for example, 0.001 parts, 0.005 parts, 0.1 parts, 0.3 parts, 0.5 parts, 0.8 parts, 1 part, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0013] The high-temperature resistant modifier is in the range of 5-80 parts by weight, for example, 5 parts, 10 parts, 20 parts, 40 parts, 50 parts, 70 parts, 80 parts, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific values ​​included in the range.

[0014] The polyethylene is in the range of 100-500 parts by weight, for example, 100 parts, 200 parts, 300 parts, 400 parts, 500 parts, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific values ​​included in the range.

[0015] The ethylene-vinyl alcohol copolymer is in the range of 1,000-60,000 parts by weight, for example, 1,000 parts, 3,000 parts, 8,000 parts, 10,000 parts, 30,000 parts, 40,000 parts, 50,000 parts, 60,000 parts, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific values ​​included in the range.

[0016] Preferably, the raw materials for preparing the high-temperature resistant ethylene-vinyl alcohol copolymer further include, by weight: 0.2-10 parts dispersant, 1-50 parts coupling agent, 0.2-5 parts release agent, and 0.2-60 parts terminator.

[0017] Preferably, the dispersant is in the range of 0.2-10 parts by weight, for example, 0.2 parts, 0.5 parts, 1 part, 2 parts, 5 parts, 8 parts, 10 parts, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0018] Preferably, the coupling agent is in the range of 1-50 parts by weight, for example, 1 part, 5 parts, 10 parts, 20 parts, 30 parts, 40 parts, 50 parts, and specific values ​​between the above-mentioned values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0019] Preferably, the weight of the separating agent is 0.2-5 parts, for example, 0.2 parts, 0.5 parts, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0020] Preferably, the terminating agent is in the range of 0.2-60 parts by weight, for example, 0.2 parts, 0.5 parts, 1 part, 5 parts, 10 parts, 30 parts, 60 parts, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0021] Preferably, the crosslinking point compound includes any one or a combination of at least two of pentaerythritol triacrylate, trimethylolpropane triacrylate, bis(trimethylolpropane)tetraacrylate, diethylene glycol diacrylate, zinc methacrylate, or magnesium methacrylate.

[0022] Preferably, the initiator comprises any one or a combination of at least two of azobisisobutyronitrile, azobisisoheptanenitrile, methyl ethyl ketone peroxide, cyclohexanone peroxide, tert-butyl hydroperoxide, benzoyl peroxide, or dicumyl peroxide.

[0023] Preferably, the high-temperature resistant modifier includes perfluoropolyether.

[0024] Preferably, the high-temperature resistant modifier includes any one or a combination of at least two of polyhexafluoropropylene oxide, polyhexafluoroethylene oxide, polytetrafluoroethylene oxide, or polyfluorinated tetrafluorooxyhexacyclobutane.

[0025] The preferred perfluoropolyether structure of this invention is polyhexafluoropropylene oxide. The main reason is that, regardless of whether the other structures are photo-oxidized or fluorinated, the polymer structure of the material will contain structures that have not been photo-oxidized or fluorinated, which will affect the temperature resistance rating.

[0026] Preferably, the polyethylene includes any one or a combination of at least two of linear low-density polyethylene, low-density polyethylene, or high-density polyethylene.

[0027] Preferably, the molar percentage of ethylene-based structural units in the ethylene-vinyl alcohol copolymer is 25-45%, for example, it can be 25%, 27%, 30%, 32%, 35%, 38%, 40%, 42%, 45%, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0028] Preferably, the dispersant comprises any one or a combination of at least two of stearic acid, ethylene bis-stearamide, magnesium stearate, or barium stearate.

[0029] Preferably, the coupling agent comprises any one or a combination of at least two of vinyltris(β-methoxyethoxy)silane, vinyltrichlorosilane, γ-aminopropyltriethoxysilane, vinyltriethoxysilane, methylmercaptopropyldimethoxysilane, and bis[(3-triethoxysilyl)propyl]tetrasulfide.

[0030] Preferably, the separating agent comprises any one or a combination of at least two of calcium oxide, calcium carbonate, sodium dodecylbenzenesulfonate, Tween-60, or Tween-80.

[0031] Preferably, the terminator comprises pentaerythritol tetrakis(β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), octadecyl β-(4-hydroxyphenyl-3,5-di-tert-butyl)propionate, 2,6-di-tert-butyl-p-methylphenol, and 2, The first of the following is a combination of any one or at least two of the following: 2'-methylenebis(4-methyl-6-tert-butylphenol), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, N,N'-1,6-hexylene-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide], N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, tris(2,4-di-tert-butylphenyl) phosphite, or 2,2-oxamido-bis[ethyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)]propionate.

[0032] In a second aspect, the present invention provides a method for preparing a high-temperature resistant ethylene-vinyl alcohol copolymer as described in the first aspect, the method comprising:

[0033] A crosslinking point compound, an initiator, a high-temperature resistant modifier, and polyethylene are mixed to obtain a high-temperature resistant modified powder; the high-temperature resistant modified powder is then mixed with an ethylene-vinyl alcohol copolymer to obtain the high-temperature resistant ethylene-vinyl alcohol copolymer.

[0034] Preferably, the preparation method specifically includes:

[0035] (1) Mix the initiator, dispersant, coupling agent, high-temperature resistant modifier and crosslinking point compound to obtain a high-temperature resistant modified premix;

[0036] (2) React the high-temperature resistant modified premix obtained in step (1) with polyethylene, add a terminator, and dry to obtain high-temperature resistant modified particles.

[0037] (3) The high-temperature resistant modified particles obtained in step (2) are mixed with the release agent and then screened to obtain high-temperature resistant modified powder;

[0038] (4) The high-temperature resistant modified powder obtained in step (3) is mixed with the ethylene-vinyl alcohol copolymer to obtain the high-temperature resistant ethylene-vinyl alcohol copolymer.

[0039] Step (1) is mainly to mix various additives evenly, making it easier to react with polyethylene and mix evenly; Step (2) is to perform grafting and blending in a screw extruder; Step (3) is to ball mill the high-temperature modified particles into high-temperature modified powder, which is easier to disperse in the EVOH matrix.

[0040] Preferably, the mixing temperature in step (1) is 20-120 ℃, for example, it can be 20 ℃, 30 ℃, 50 ℃, 80 ℃, 100 ℃, 120 ℃, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0041] Preferably, the mixing includes stirring.

[0042] Preferably, the stirring rate is 400-1000 rpm, for example, it can be 400 rpm, 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, 1000 rpm, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0043] Preferably, the reaction in step (2) includes extrusion.

[0044] Preferably, the extrusion temperature is 120-200℃, for example, it can be 120℃, 130℃, 150℃, 180℃, 200℃, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0045] Preferably, the extrusion rate is 10-150 rpm, for example, it can be 10 rpm, 20 rpm, 50 rpm, 80 rpm, 100 rpm, 120 rpm, 150 rpm, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0046] Preferably, the drying time is 1-5 min, for example, it can be 1 min, 1.5 min, 2 min, 2.5 min, 3 min, 3.5 min, 4 min, 4.5 min, 5 min, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0047] Preferably, the drying temperature is 90-120 ℃, for example, it can be 90 ℃, 100 ℃, 110 ℃, 120 ℃, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0048] Preferably, the initial temperature of the mixture in step (3) is 20-80 ℃, for example, it can be 20 ℃, 40 ℃, 50 ℃, 60 ℃, 80 ℃, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0049] Preferably, the temperature after mixing in step (3) is 25-130 ℃, for example, it can be 25 ℃, 50 ℃, 80 ℃, 100 ℃, 130 ℃, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0050] Preferably, step (4) further includes extrusion, molding, cooling, and settling after mixing.

[0051] Preferably, the extrusion temperature is 120-300 ℃, for example, it can be 120 ℃, 140 ℃, 150 ℃, 160 ℃, 180 ℃, 200 ℃, 250 ℃, 280 ℃, 300 ℃, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0052] Preferably, the molding temperature is 180-250 ℃, for example, it can be 180 ℃, 200 ℃, 220 ℃, 250 ℃, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0053] Preferably, the molding time is 5-10 min, for example, it can be 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0054] Preferably, the cooling time is 5-10 min, for example, it can be 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0055] Preferably, the settling time is 10-24 hours, for example, 10 hours, 12 hours, 15 hours, 20 hours, 22 hours, 24 hours, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific values ​​included in the range.

[0056] Preferably, the settling temperature is 20-30 ℃, for example, it can be 20 ℃, 22 ℃, 24 ℃, 26 ℃, 28 ℃, 30 ℃, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0057] In this invention, an initiator, dispersant, coupling agent, high-temperature modifier, and crosslinking point compound are first uniformly mixed in a certain mass ratio using a high-speed mixer to prepare a high-temperature modified premix. Then, the high-temperature modified premix and polyethylene are uniformly mixed in a screw extruder and extruded to granulate, obtaining high-temperature modified particles. Next, the high-temperature modified particles and a release agent are placed in a planetary ball mill and ground into a 500-800 mesh high-temperature modified powder. Finally, the high-temperature modified powder is uniformly mixed with ethylene-vinyl alcohol copolymer (EVOH) in a screw extruder and extruded to granulate, obtaining a high-temperature resistant EVOH product. Compared with existing technologies, the material of this invention can significantly improve the temperature resistance, aging resistance, and mechanical properties of EVOH.

[0058] The high-speed mixer used in this invention is not limited to any particular model or parameters, as long as it can mix various additives evenly to prepare a high-temperature resistant modified premix.

[0059] The planetary ball mill used in this invention is a general-purpose equipment for material grinding. The initial mixing temperature is controlled within the range of 20~80℃, the revolution speed is controlled within the range of 10~500 rpm, the rotation speed is controlled within the range of 20~500 rpm, and it is equipped with 0~50 layers of 50 mesh~500 mesh sieves.

[0060] The screw extruder used in this invention is a general-purpose parallel twin-screw extruder for polyolefins, with a temperature control range of 20~350℃ and a speed control range of 10~150 rpm. There is no specific model limit, as long as the equipment meets the requirements for safe use and can extrude and granulate the product.

[0061] The high-temperature molding machine used in this invention is a general-purpose polyolefin molding equipment with a temperature control range of 20~350℃ and a pressure control range of 1~20MPa. There is no specific model limit, as long as the equipment meets the safety requirements and can mold the product.

[0062] Thirdly, the present invention provides the application of the high-temperature resistant ethylene-vinyl alcohol copolymer as described in the first aspect in packaging materials, structural materials, textile materials or medical materials.

[0063] Compared with the prior art, the present invention has the following beneficial effects:

[0064] The high-temperature resistant ethylene-vinyl alcohol copolymer provided by this invention involves an initiator that initiates the grafting of crosslinking point compounds into the polyethylene molecular chain. Through synergistic effects with a high-temperature modifier, the temperature resistance of EVOH is significantly improved. Under high-temperature hot air aging test conditions of 200℃ for up to 72 hours, the mechanical properties show no significant change. Simultaneously, the product of this invention exhibits higher tensile strength, excellent aging resistance, and high-temperature resistance, with a tensile strength reaching 43.5-58.7 MPa, aging resistance reaching 75.3-88.3%, and a temperature resistance reaching 180-195℃. Detailed Implementation

[0065] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0066] The experimental materials used in the embodiments and comparative examples of this invention are as follows:

[0067] (1) Polyethylene: Grade, LLDPE, YLF-1801, Manufacturer, Sinopec Yangzi Petrochemical Co., Ltd.; Grade, HDPE, 4000F, Manufacturer, Sinopec Yangzi Petrochemical Co., Ltd.; LDPE Grade 18D, Manufacturer, PetroChina Daqing Petrochemical Co., Ltd.

[0068] (2) Ethylene-vinyl alcohol copolymer: F171 (ethylene molar content 32%), H171 (ethylene molar content 38%), manufactured by Kuraray Co., Ltd., Japan; DICP-1 grade DICP-1, manufactured by, prepared according to patent CN113861313A (ethylene molar content 25%); DICP-2 grade DICP-2, manufactured by, prepared according to patent CN113861313A (ethylene molar content 33%); DICP-3 grade DICP-3, manufactured by, prepared according to patent CN113861313A (ethylene molar content 39%).

[0069] (3) Perfluoropolyether: Brand name, B-2600, Manufacturer, Fuzhou Taipuda New Materials Co., Ltd.;

[0070] Example 1

[0071] This embodiment provides a high-temperature resistant ethylene-vinyl alcohol copolymer, the components of which include: 0.01 parts cyclohexanone peroxide, 1 part magnesium stearate, 10 parts vinyltrichlorosilane (A150), 20 parts perfluoropolyether (PFPE), 100 parts diethylene glycol diacrylate, 436.7 parts polyethylene LLDPE, 2.2 parts pentaerythritol tetrakis(β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) (1010), 2.2 parts tris(2,4-di-tert-butylphenyl) phosphite (168), 5.7 parts calcium oxide, and 11556 parts F171 (ethylene molar content 32%).

[0072] This embodiment also provides a method for preparing a high-temperature resistant ethylene-vinyl alcohol copolymer, the preparation method comprising:

[0073] (a) In a high-speed mixer, cyclohexanone peroxide, magnesium stearate, vinyltrichlorosilane (A150), perfluoropolyether (PFPE) and diethylene glycol diacrylate were added. The high-speed mixer was set at 30°C and 800 rpm for 1 minute to obtain a high-temperature resistant modified premix.

[0074] (b) In a twin-screw extruder, polyethylene LLDPE and high-temperature modified premix were added. The screw extruder temperature was 150°C. Pentaerythritol tetrakis(β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) (1010), tris(2,4-di-tert-butylphenyl) phosphite (168), and polyethylene were added in the middle of the screw extruder. The speed was 20 rpm. The extruder was then air-cooled, dried, and granulated to obtain high-temperature modified granules.

[0075] (c) The high-temperature resistant modified particles and calcium oxide were put into a planetary ball mill. The initial mixing temperature was 25°C and the temperature after mixing was 35°C. The revolution speed was 100 rpm and the rotation speed was 200 rpm. After mixing for 30 minutes, the mixture was screened through 5 layers of the same mesh (50 mesh) sieve to obtain 500 mesh high-temperature resistant modified powder.

[0076] (d) High-temperature resistant modified powder and F171 (ethylene molar content 32%) were added to a twin-screw extruder. The screw extruder temperature was 150℃, the speed was 20 rpm, and the product was extruded, air-cooled, dried, and granulated to obtain the high-temperature resistant EVOH product. The high-temperature resistant EVOH was then shaped on a high-temperature molding machine at a temperature of 180℃, a pressure of 5 MPa, a molding time of 10 min, and a cooling time of 5 min. After molding, the product was placed at 20℃ for 10 hours, and the tensile strength, elongation at break, aging resistance, water resistance, and temperature resistance rating of the sample were measured.

[0077] Example 2

[0078] This embodiment provides a high-temperature resistant ethylene-vinyl alcohol copolymer, the components of which include: 0.5 parts benzoyl peroxide (BPO), 5 parts barium stearate, 30 parts vinyltriethoxysilane (A151), 50 parts perfluoropolyether (PFPE), 100 parts zinc methacrylate, 371 parts polyethylene HDPE, 11.1 parts N,N'-1,6-hexylene-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide] (1098), 7.4 parts tris(2,4-di-tert-butylphenyl) phosphite (168), 17.3 parts Tween-80, and 2962 parts DICP-1 (ethylene molar content 25%).

[0079] This embodiment also provides a method for preparing a high-temperature resistant ethylene-vinyl alcohol copolymer, the preparation method comprising:

[0080] (a) In a high-speed mixer, benzoyl peroxide (BPO), barium stearate, vinyltriethoxysilane (A151), perfluoropolyether (PFPE) and zinc methacrylate were added. The high-speed mixer was set at 80°C and 800 rpm for 5 minutes to obtain a high-temperature resistant modified premix.

[0081] (b) In a twin-screw extruder, polyethylene (HDPE) and high-temperature resistant modified premix were added. The screw extruder temperature was 180°C. N,N'-1,6-hexylene-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide] (1098) and tris(2,4-di-tert-butylphenyl) phosphite (168) were added in the middle of the screw extruder. The speed was 120 rpm. The extruder was then air-cooled, dried, and granulated to obtain high-temperature resistant modified granules.

[0082] (c) The high-temperature resistant modified particles and Tween-60 were put into a planetary ball mill. The initial mixing temperature was 50°C and the temperature after mixing was 100°C. The revolution speed was 200 rpm and the rotation speed was 400 rpm. After mixing for 30 minutes, the mixture was screened through 20 layers of 500 mesh sieves to obtain 800 mesh high-temperature resistant modified powder.

[0083] (d) High-temperature resistant modified powder and DICP-1 (ethylene molar content 25%) were added to a twin-screw extruder. The extruder temperature was 250℃, the speed was 120 rpm, and the product was extruded, air-cooled, dried, and granulated to obtain the high-temperature resistant EVOH product. The high-temperature resistant EVOH was then shaped on a high-temperature molding machine at a temperature of 250℃, a pressure of 15 MPa, a molding time of 10 min, and a cooling time of 10 min. After molding, the product was placed at 30℃ for 24 hours, and the tensile strength, elongation at break, aging resistance, water resistance, and temperature resistance rating of the sample were measured.

[0084] Example 3

[0085] This embodiment provides a high-temperature resistant ethylene-vinyl alcohol copolymer, the components of which include: 0.1 parts dicumyl peroxide (DCP), 3 parts stearic acid, 20 parts bis[(3-triethoxysilyl)propyl]tetrasulfide (Si-69), 30 parts perfluoropolyether (PFPE), 100 parts trimethylolpropane triacrylate, 383 parts polyethylene LDPE, 3.8 parts β-(4-hydroxyphenyl-3,5-di-tert-butyl)propionate n-octadecyl alcohol ester (1076), 3.8 parts tris(2,4-di-tert-butylphenyl) phosphite (168), 10.9 parts sodium dodecylbenzenesulfonate, and 3697 parts DICP-2 (ethylene molar content 33%).

[0086] This embodiment also provides a method for preparing a high-temperature resistant ethylene-vinyl alcohol copolymer, the preparation method comprising:

[0087] (a) In a high-speed mixer, dicumyl peroxide (DCP), stearic acid, bis[(3-triethoxysilyl)propyl]tetrasulfide (Si-69), perfluoropolyether (PFPE) and trimethylolpropane triacrylate were added. The high-speed mixer was set at 50°C and 600 rpm for 3 minutes to obtain a high-temperature resistant modified premix.

[0088] (b) In a twin-screw extruder, polyethylene LDPE and high-temperature modified premix were added. The screw extruder temperature was 160°C. β-(4-hydroxyphenyl-3,5-di-tert-butyl)propionate n-octadecyl alcohol ester (1076) and tris(2,4-di-tert-butylphenyl) phosphite (168) were added in the middle of the screw extruder. The speed was 80 rpm. The extruder was then air-cooled, dried, and granulated to obtain high-temperature modified granules.

[0089] (c) The high-temperature resistant modified particles and sodium dodecylbenzene sulfonate were put into a planetary ball mill. The initial mixing temperature was 30°C and the temperature after mixing was 80°C. The revolution speed was 150 rpm and the rotation speed was 300 rpm. After mixing for 20 minutes, the mixture was screened through 10 layers of the same mesh (200 mesh) sieve to obtain 600 mesh high-temperature resistant modified powder.

[0090] (d) High-temperature resistant modified powder and DICP-2 (ethylene molar content 33%) were added to a twin-screw extruder. The extruder temperature was 200℃, the speed was 60 rpm, and the product was extruded, air-cooled, dried, and granulated to obtain the high-temperature resistant EVOH product. The high-temperature resistant EVOH was then shaped on a high-temperature molding machine at a temperature of 200℃, a pressure of 10 MPa, a molding time of 8 min, and a cooling time of 8 min. After molding, the product was placed at 25℃ for 16 hours, and the tensile strength, elongation at break, aging resistance, water resistance, and temperature resistance rating of the sample were measured.

[0091] Example 4

[0092] This embodiment provides a high-temperature resistant ethylene-vinyl alcohol copolymer, the components of which include: 0.08 parts benzoyl peroxide (BPO), 2 parts magnesium stearate, 15 parts vinyltrichlorosilane (A150), 25 parts perfluoropolyether (PFPE), 100 parts zinc methacrylate, 406 parts polyethylene LLDPE, 8.1 parts pentaerythritol tetrakis(β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) (1010), 8.3 parts calcium oxide, and 5645 parts DICP-3 (ethylene molar content 39%).

[0093] This embodiment also provides a method for preparing a high-temperature resistant ethylene-vinyl alcohol copolymer, the preparation method comprising:

[0094] (a) In a high-speed mixer, benzoyl peroxide (BPO), magnesium stearate, vinyltrichlorosilane (A150), perfluoropolyether (PFPE) and zinc methacrylate were added. The high-speed mixer was set at 70°C and 600 rpm for 2 minutes to obtain a high-temperature resistant modified premix.

[0095] (b) In a twin-screw extruder, polyethylene LLDPE and high-temperature modified premix were added. The screw extruder temperature was 170°C. Pentaerythritol tetrakis(β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) (1010) was added in the middle of the screw extruder. The speed was 50 rpm. The extrusion was air-cooled and dried to obtain high-temperature modified granules.

[0096] (c) The high-temperature resistant modified particles and calcium oxide were put into a planetary ball mill. The initial mixing temperature was 25~50℃, and the temperature after mixing was 40℃. The revolution speed was 180 rpm and the rotation speed was 250 rpm. After mixing for 15 minutes, the mixture was screened through 7 layers of the same mesh (100 mesh) sieve to obtain 550 mesh high-temperature resistant modified powder.

[0097] (d) High-temperature resistant modified powder and DICP-3 (ethylene molar content 39%) were added to a twin-screw extruder. The screw extruder temperature was 160℃, the speed was 40 rpm, and the product was extruded, air-cooled, dried, and granulated to obtain the high-temperature resistant EVOH product. The high-temperature resistant EVOH was then shaped on a high-temperature molding machine at a temperature of 190℃, a pressure of 8 MPa, a molding time of 6 min, and a cooling time of 7 min. After molding, the product was placed at 23℃ for 18 hours, and the tensile strength, elongation at break, aging resistance, water resistance, and temperature resistance rating of the sample were measured.

[0098] Example 5

[0099] This embodiment provides a high-temperature resistant ethylene-vinyl alcohol copolymer, the components of which include: 0.001 parts cyclohexanone peroxide, 0.2 parts stearic acid, 1 part vinyltriethoxysilane (A151), 5 parts perfluoropolyether (PFPE), 100 parts diethylene glycol diacrylate, 1062 parts polyethylene HDPE, 26.6 parts β-(4-hydroxyphenyl-3,5-di-tert-butyl)propionate n-octadecyl alcohol ester (1076), 2.4 parts sodium dodecylbenzenesulfonate, and 59860 parts DICP-3 (ethylene molar content 39%).

[0100] This embodiment also provides a method for preparing a high-temperature resistant ethylene-vinyl alcohol copolymer, the preparation method comprising:

[0101] (a) In a high-speed mixer, cyclohexanone peroxide, stearic acid, vinyltriethoxysilane (A151), perfluoropolyether (PFPE) and diethylene glycol diacrylate were added. The high-speed mixer was set at 20°C and 300 rpm for 10 minutes to obtain a high-temperature resistant modified premix.

[0102] (b) In a twin-screw extruder, polyethylene HDPE and high-temperature modified premix are extruded at a screw extruder temperature of 120°C. β-(4-hydroxyphenyl-3,5-di-tert-butyl)propionic acid n-octadecyl alcohol ester (1076) is added in the middle of the screw extruder at a speed of 10 rpm. The mixture is then extruded, air-cooled, dried, and granulated to obtain high-temperature modified granules.

[0103] (c) The high-temperature resistant modified particles and sodium dodecylbenzene sulfonate were put into a planetary ball mill. The initial mixing temperature was 20°C and the temperature after mixing was 25°C. The revolution speed was 50 rpm and the rotation speed was 150 rpm. After mixing for 15 minutes, the mixture was screened through 12 layers of the same mesh (100 mesh) sieve to obtain 600 mesh high-temperature resistant modified powder.

[0104] (d) High-temperature resistant modified powder and DICP-3 (ethylene molar content 39%) were added to a twin-screw extruder. The screw extruder temperature was 120℃, the speed was 10 rpm, and the product was extruded, air-cooled, dried, and granulated to obtain the high-temperature resistant EVOH product. The high-temperature resistant EVOH was then shaped on a high-temperature molding machine at a temperature of 180℃, a pressure of 5 MPa, a molding time of 10 min, and a cooling time of 10 min. After molding, the product was placed at 25℃ for 12 hours, and the tensile strength, elongation at break, aging resistance, water resistance, and temperature resistance rating of the sample were measured.

[0105] Example 6

[0106] This embodiment provides a high-temperature resistant ethylene-vinyl alcohol copolymer, the components of which include: 1 part dicumyl peroxide (DCP), 10 parts barium stearate, 50 parts bis[(3-triethoxysilyl)propyl]tetrasulfide (Si-69), 80 parts perfluoropolyether (PFPE), 100 parts trimethylolpropane triacrylate, 241 parts polyethylene LDPE, 24.1 parts N,N'-1,6-hexylene-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide] (1098), 25.3 parts Tween-60, and 1063 parts DICP-2 (ethylene molar content 33%).

[0107] This embodiment also provides a method for preparing a high-temperature resistant ethylene-vinyl alcohol copolymer, the preparation method comprising:

[0108] (a) In a high-speed mixer, dicumyl peroxide (DCP), barium stearate, bis[(3-triethoxysilyl)propyl]tetrasulfide (Si-69), perfluoropolyether (PFPE) and trimethylolpropane triacrylate were mixed for 0.5 minutes at a temperature of 120°C and a speed of 1200 rpm to obtain a high-temperature resistant modified premix.

[0109] (b) In a twin-screw extruder, polyethylene LDPE and high-temperature resistant modified premix were added. The screw extruder temperature was 200°C. N,N'-1,6-hexylene-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide] (1098) was added in the middle of the screw extruder. The speed was 150 rpm. The extrusion was air-cooled and dried to obtain high-temperature resistant modified granules.

[0110] (c) The high-temperature resistant modified particles and Tween-60 were put into a planetary ball mill. The initial mixing temperature was 80°C and the temperature after mixing was 130°C. The revolution speed was 240 rpm and the rotation speed was 500 rpm. After mixing for 30 minutes, the mixture was screened through 20 layers of 500 mesh sieves to obtain 700 mesh high-temperature resistant modified powder.

[0111] (d) High-temperature resistant modified powder and DICP-2 (ethylene molar content 33%) were added to a twin-screw extruder. The extruder temperature was 300℃, the speed was 140 rpm, and the product was extruded, air-cooled, dried, and granulated to obtain the high-temperature resistant EVOH product. The high-temperature resistant EVOH was then shaped on a high-temperature molding machine at a temperature of 250℃, a pressure of 15 MPa, a molding time of 10 min, and a cooling time of 5 min. After molding, the product was placed at 30℃ for 24 hours, and the tensile strength, elongation at break, aging resistance, water resistance, and temperature resistance rating of the sample were measured.

[0112] Comparative Example 1

[0113] This comparative example provides a high-temperature resistant ethylene-vinyl alcohol copolymer, the components of which include: 100 parts polyethylene LDPE, 0.03 parts dicumyl peroxide (DCP), 0.77 parts stearic acid, 5.23 parts bis[(3-triethoxysilyl)propyl]tetrasulfide (Si-69), 7.84 parts perfluoropolyether (PFPE), 26.13 parts trimethylolpropane triacrylate, 1 part β-(4-hydroxyphenyl-3,5-di-tert-butyl)propionate n-octadecyl alcohol ester (1076), 1 part tris(2,4-di-tert-butylphenyl) phosphite (168), 2.4 parts sodium dodecylbenzenesulfonate, and 947 parts DICP-2 (ethylene molar content 33%).

[0114] This comparative example also provides a method for preparing a high-temperature resistant ethylene-vinyl alcohol copolymer, the method comprising:

[0115] (a) In a twin-screw extruder, polyethylene LDPE, dicumyl peroxide (DCP), stearic acid, bis[(3-triethoxysilyl)propyl]tetrasulfide (Si-69), perfluoropolyether (PFPE) and trimethylolpropane triacrylate were added. The screw extruder temperature was 160°C. β-(4-hydroxyphenyl-3,5-di-tert-butyl)propionate n-octadecyl alcohol ester (1076) and tris(2,4-di-tert-butylphenyl) phosphite (168) were added in the middle of the screw extruder. The speed was 80 rpm. The extrusion was air-cooled and dried to granulate, and high-temperature resistant modified granules were obtained.

[0116] (b) The high-temperature resistant modified particles and sodium dodecylbenzene sulfonate were put into a planetary ball mill. The initial mixing temperature was 30°C and the temperature after mixing was 80°C. The revolution speed was 150 rpm and the rotation speed was 300 rpm. After mixing for 20 minutes, the mixture was screened through 10 layers of the same mesh (200 mesh) sieve to obtain 600 mesh high-temperature resistant modified powder.

[0117] (c) High-temperature resistant modified powder and DICP-2 (ethylene molar content 33%) were added to a twin-screw extruder. The extruder temperature was 200℃, the speed was 60 rpm, and the product was extruded, air-cooled, dried, and granulated to obtain the high-temperature resistant EVOH product. The high-temperature resistant EVOH was then shaped on a high-temperature molding machine at a temperature of 200℃, a pressure of 10 MPa, a molding time of 8 min, and a cooling time of 8 min. After molding, the product was placed at 25℃ for 16 hours, and the tensile strength, elongation at break, aging resistance, water resistance, and temperature resistance rating of the sample were measured.

[0118] Comparative Example 2

[0119] This comparative example provides a high-temperature resistant ethylene-vinyl alcohol copolymer, the components of which include: 100 parts polyethylene LDPE, 0.03 parts dicumyl peroxide (DCP), 0.77 parts stearic acid, 5.23 parts bis[(3-triethoxysilyl)propyl]tetrasulfide (Si-69), 7.84 parts perfluoropolyether (PFPE), 26.13 parts trimethylolpropane triacrylate, 1 part β-(4-hydroxyphenyl-3,5-di-tert-butyl)propionate n-octadecyl alcohol ester (1076), 1 part tris(2,4-di-tert-butylphenyl) phosphite (168), and 947 parts DICP-2 (ethylene molar content 33%).

[0120] This comparative example also provides a method for preparing a high-temperature resistant ethylene-vinyl alcohol copolymer, the method comprising:

[0121] (a) In a twin-screw extruder, polyethylene LDPE, dicumyl peroxide (DCP), stearic acid, bis[(3-triethoxysilyl)propyl]tetrasulfide (Si-69), perfluoropolyether (PFPE) and trimethylolpropane triacrylate were added. The screw extruder temperature was 160°C. β-(4-hydroxyphenyl-3,5-di-tert-butyl)propionate n-octadecyl alcohol ester (1076) and tris(2,4-di-tert-butylphenyl) phosphite (168) were added in the middle of the screw extruder. 1076, 168 and polyethylene were extruded at a speed of 80 rpm, air-cooled and dried to granulate, to obtain high-temperature resistant modified granules.

[0122] (b) High-temperature resistant modified granules and DICP-2 (ethylene molar content 33%) were added to a twin-screw extruder at a screw extruder temperature of 200°C and a speed of 60 rpm. The extrusion was followed by air-cooling and granulation to obtain the high-temperature resistant EVOH product. The high-temperature resistant EVOH was then shaped on a high-temperature molding machine at a temperature of 200°C and a pressure of 10 MPa for 8 min, followed by a cooling time of 8 min. After molding, the samples were placed at 25°C for 16 hours, and the tensile strength, elongation at break, aging resistance, water resistance, and temperature resistance rating of the samples were measured.

[0123] Comparative Example 3

[0124] This comparative example provides a high-temperature resistant ethylene-vinyl alcohol copolymer, the components of which include: 10.7 parts of polyethylene LDPE, 0.004 parts of dicumyl peroxide (DCP), 0.096 parts of stearic acid, 0.56 parts of bis[(3-triethoxysilyl)propyl]tetrasulfide (Si-69), 0.84 parts of perfluoropolyether (PFPE), 2.8 parts of trimethylolpropane triacrylate, and 100 parts of DICP-2 (ethylene molar content 33%).

[0125] This comparative example also provides a method for preparing a high-temperature resistant ethylene-vinyl alcohol copolymer, the method comprising:

[0126] Polyethylene LDPE, dicumyl peroxide (DCP), stearic acid, bis[(3-triethoxysilyl)propyl]tetrasulfide (Si-69), perfluoropolyether (PFPE), trimethylolpropane triacrylate, and DICP-2 (ethylene molar content 33%) were added to a twin-screw extruder at a screw extruder temperature of 200℃ and a speed of 60 rpm. The extrusion was followed by air-cooling, drying, and granulation to obtain a high-temperature resistant EVOH product. The high-temperature resistant EVOH was then molded on a high-temperature molding machine at a temperature of 200℃, a pressure of 10 MPa, a molding time of 8 min, and a cooling time of 8 min. After molding, the samples were placed at 25℃ for 16 hours, and the tensile strength, elongation at break, aging resistance, water resistance, and temperature resistance rating of the samples were measured.

[0127] Comparative Example 4

[0128] This comparative example provides an ethylene-vinyl alcohol copolymer, the components of which include: 100 parts of DICP-2 (ethylene molar content 33%).

[0129] This comparative example also provides a method for preparing an ethylene-vinyl alcohol copolymer, the method comprising:

[0130] DICP-2 (ethylene molar content 33%) was added to a twin-screw extruder at a screw extruder temperature of 200℃ and a speed of 60 rpm. The extrusion was followed by air-cooling, drying, and granulation to obtain a high-temperature resistant EVOH product. The high-temperature resistant EVOH was then shaped on a high-temperature molding machine at a temperature of 200℃, a pressure of 10 MPa, a molding time of 8 min, and a cooling time of 8 min. After molding, the samples were placed at 25℃ for 16 hours. The tensile strength, elongation at break, aging resistance, water resistance, and temperature resistance rating of the samples were then measured.

[0131] Comparative Example 5

[0132] This comparative example provides an ethylene-vinyl alcohol copolymer, the components of which include: 100 parts of F171 (ethylene molar content 32%).

[0133] This comparative example also provides a method for preparing an ethylene-vinyl alcohol copolymer, the method comprising:

[0134] F171 (ethylene molar content 32%) was added to a twin-screw extruder at a screw extruder temperature of 150℃ and a speed of 20 rpm. The extrusion was followed by air-cooling, drying, and granulation to obtain a high-temperature resistant EVOH product. The high-temperature resistant EVOH was then shaped on a high-temperature molding machine at a temperature of 180℃, a pressure of 5 MPa, a molding time of 10 min, and a cooling time of 5 min. After molding, the samples were placed at 20℃ for 10 hours. The tensile strength, elongation at break, aging resistance, water resistance, and temperature resistance rating of the samples were then measured.

[0135] Comparative Example 6

[0136] This comparative example provides an ethylene-vinyl alcohol copolymer, the components of which include: 100 parts of DICP-1 (ethylene molar content 25%).

[0137] This comparative example also provides a method for preparing an ethylene-vinyl alcohol copolymer, the method comprising:

[0138] DICP-1 (ethylene molar content 25%) was added to a twin-screw extruder at a screw extruder temperature of 250℃ and a speed of 120 rpm. The extrusion was followed by air-cooling, drying, and granulation to obtain a high-temperature resistant EVOH product. The high-temperature resistant EVOH was then shaped on a high-temperature molding machine at a temperature of 250℃, a pressure of 15 MPa, a molding time of 10 min, and a cooling time of 10 min. After molding, the samples were placed at 30℃ for 24 hours. The tensile strength, elongation at break, aging resistance, water resistance, and temperature resistance rating of the samples were then measured.

[0139] Comparative Example 7

[0140] This comparative example provides an ethylene-vinyl alcohol copolymer, the components of which include: 100 parts of DICP-3 (ethylene molar content 39%).

[0141] This comparative example also provides a method for preparing an ethylene-vinyl alcohol copolymer, the method comprising:

[0142] DICP-3 (ethylene molar content 39%) was added to a twin-screw extruder at a screw extruder temperature of 160℃ and a speed of 40 rpm. The extrusion was followed by air-cooling, drying, and granulation to obtain a high-temperature resistant EVOH product. The high-temperature resistant EVOH was then shaped on a high-temperature molding machine at a temperature of 190℃, a pressure of 8 MPa, a molding time of 6 min, and a cooling time of 7 min. After molding, the samples were placed at 23℃ for 18 hours. The tensile strength, elongation at break, aging resistance, water resistance, and temperature resistance rating of the samples were then measured.

[0143] Comparative Example 8

[0144] This comparative example provides an ethylene-vinyl alcohol copolymer, which differs from Example 1 only in that no initiator is added; all other aspects are the same as in Example 1.

[0145] Comparative Example 9

[0146] This comparative example provides an ethylene-vinyl alcohol copolymer, which differs from Example 1 only in that it does not contain diethylene glycol diacrylate; all other aspects are the same as in Example 1.

[0147] Comparative Example 10

[0148] This comparative example provides an ethylene-vinyl alcohol copolymer, which differs from Example 1 only in that it does not contain perfluoropolyether (PFPE), and the weight of polyethylene LLDPE is 456.7 parts, while the rest are the same as in Example 1.

[0149] The performance of the high-temperature resistant ethylene-vinyl alcohol copolymers provided in Examples 1-6, Comparative Examples 1-3, and Comparative Examples 4-10 was tested using the following methods:

[0150] (1) Tensile strength and elongation at break: Tested according to GB / T 1040.2-2006;

[0151] (2) Aging resistance: Aging conditions (200℃×72 hours), calculated according to the following formula: Aging resistance = tensile strength after aging (MPa) × elongation at break after aging (%) × 100% ÷ tensile strength before aging (MPa) × elongation at break before aging (%).

[0152] (3) Water resistance: Determined according to Method 4 of 6.5 in GB / T 1034-2008 Determination of water absorption of plastics, under test conditions (aqueous solution 80℃ × 240 hours), calculated according to the following formula: [Water resistance = weight after immersion (mg) - weight after immersion and drying (mg)] × 100% ÷ weight after immersion and drying (mg)

[0153] (4) The temperature resistance rating is determined according to "GB / T 20028-2005 Application of Arrhenius plot to estimate the storage life and maximum service temperature of polymer materials", and the test index is the aging performance at 200℃×168 hours, with a critical value of 85%;

[0154] The properties of the high-temperature resistant ethylene-vinyl alcohol copolymers provided in Examples 1-6, Comparative Examples 1-3, and Comparative Examples 4-10 were tested according to the above performance testing methods. The test results are shown in Table 1-2.

[0155] Table 1

[0156]

[0157] Table 2

[0158]

[0159] Analysis of the data in the table shows that the mechanical properties, aging resistance, and water resistance of the EVOH material provided in the examples are all superior to those of EVOH materials prepared by existing technologies, and the temperature resistance of the EVOH material provided in the examples is significantly higher than that of products prepared by existing technologies.

[0160] Data analysis shows that different selections and amounts of raw materials result in slight differences in the mechanical properties, aging resistance, water resistance, and temperature resistance of the products. However, the general rule is that the products provided in the examples have superior mechanical properties, aging resistance, water resistance, and temperature resistance compared to products in the prior art.

[0161] Data from Example 3 and Comparative Examples 2 and 3 show that the tensile strength, elongation at break, aging resistance, and water resistance of the product provided in Example 3 are all superior to the EVOH materials in Comparative Examples 2 and 3 (Comparative Example 2 with steps a and b omitted, and Comparative Example 3 with steps a, b, and c omitted). Data from Example 3 and Comparative Example 1 show that Example 3, by adding the premix preparation step, significantly improved the temperature resistance of the EVOH material.

[0162] Comparative Examples 4, 5, 6, and 7 present performance data for existing processes of different EVOH products. Data analysis shows that the existing EVOH technology exhibits poor aging resistance and water resistance, while the EVOH materials provided in the examples significantly improve these properties and also show a marked increase in temperature resistance. Comparative Example 8 (without an initiator), Comparative Example 9 (without diethylene glycol diacrylate), and Comparative Example 10 (without perfluoropolyether) contrast with Example 1, demonstrating that the synergistic effect between the grafted polyethylene and the high-temperature modifier can effectively increase the various properties of the high-temperature resistant ethylene-vinyl alcohol copolymer, surpassing the effect of using the high-temperature modifier alone and the synergistic effect between polyethylene and the high-temperature modifier.

[0163] The applicant declares that this invention illustrates a high-temperature resistant ethylene-vinyl alcohol copolymer, its preparation method, and its application through the above embodiments. However, this invention is not limited to the above embodiments, meaning that this invention does not necessarily rely on the above embodiments for implementation. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection and disclosure scope of this invention.

Claims

1. A high-temperature resistant ethylene-vinyl alcohol copolymer with a heat resistance temperature above 180℃, characterized in that, The raw materials for preparing the high-temperature resistant ethylene-vinyl alcohol copolymer include, by weight: 100 parts crosslinking point compound, 0.001-1 part initiator, 5-80 parts high-temperature resistant modifier, 100-500 parts polyethylene, 1000-60000 parts ethylene-vinyl alcohol copolymer, 0.2-10 parts dispersant, 1-50 parts coupling agent, 0.2-5 parts release agent, and 0.2-60 parts terminator; The crosslinking point compound includes any one or a combination of at least two of pentaerythritol triacrylate, trimethylolpropane triacrylate, bis(trimethylolpropane)tetraacrylate, diethylene glycol diacrylate, zinc methacrylate, or magnesium methacrylate. The high-temperature resistant modifier includes any one or a combination of at least two of polyhexafluoropropylene oxide, polyhexafluoroethylene oxide, polytetrafluoroethylene oxide, or polyfluorinated tetrafluorooxyheterocyclic butane. The high-temperature resistant ethylene-vinyl alcohol copolymer is prepared by the following method, the method comprising: (1) Mix the initiator, dispersant, coupling agent, high-temperature resistant modifier and crosslinking point compound to obtain a high-temperature resistant modified premix; (2) React the high-temperature resistant modified premix obtained in step (1) with polyethylene, add a terminator, and dry to obtain high-temperature resistant modified particles. (3) The high-temperature resistant modified particles obtained in step (2) are mixed with the release agent and then screened to obtain high-temperature resistant modified powder; (4) The high-temperature resistant modified powder obtained in step (3) is mixed with the ethylene-vinyl alcohol copolymer to obtain the high-temperature resistant ethylene-vinyl alcohol copolymer.

2. The high-temperature resistant ethylene-vinyl alcohol copolymer according to claim 1, characterized in that, The initiator includes any one or a combination of at least two of azobisisobutyronitrile, azobisisoheptanenitrile, methyl ethyl ketone peroxide, cyclohexanone peroxide, tert-butyl hydroperoxide, benzoyl peroxide, or dicumyl peroxide.

3. The high-temperature resistant ethylene-vinyl alcohol copolymer according to claim 1, characterized in that, The polyethylene includes any one or a combination of at least two of linear low-density polyethylene, low-density polyethylene, or high-density polyethylene.

4. The high-temperature resistant ethylene-vinyl alcohol copolymer according to claim 1, characterized in that, The ethylene-vinyl alcohol copolymer has a molar percentage of ethylene-based structural units of 25-45%.

5. The high-temperature resistant ethylene-vinyl alcohol copolymer according to claim 1, characterized in that, The dispersant includes any one or a combination of at least two of stearic acid, ethylene bis-stearamide, magnesium stearate, or barium stearate.

6. The high-temperature resistant ethylene-vinyl alcohol copolymer according to claim 1, characterized in that, The coupling agent includes any one or a combination of at least two of vinyltris(β-methoxyethoxy)silane, vinyltrichlorosilane, γ-aminopropyltriethoxysilane, vinyltriethoxysilane, methylmercaptopropyldimethoxysilane, and bis[(3-triethoxysilyl)propyl]tetrasulfide.

7. The high-temperature resistant ethylene-vinyl alcohol copolymer according to claim 1, characterized in that, The separating agent includes any one or a combination of at least two of calcium oxide, calcium carbonate, sodium dodecylbenzenesulfonate, Tween-60, or Tween-80.

8. The high-temperature resistant ethylene-vinyl alcohol copolymer according to claim 1, characterized in that, The terminator includes pentaerythritol tetrakis(β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), octadecyl β-(4-hydroxyphenyl-3,5-di-tert-butyl)propionate, 2,6-di-tert-butyl-p-methylphenol, and 2, The first of the following is a combination of any one or at least two of the following: 2'-methylenebis(4-methyl-6-tert-butylphenol), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, N,N'-1,6-hexylene-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide], N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, tris(2,4-di-tert-butylphenyl) phosphite, or 2,2-oxamido-bis[ethyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)]propionate.

9. A method for preparing a high-temperature resistant ethylene-vinyl alcohol copolymer as described in any one of claims 1-8, characterized in that, The preparation method includes: (1) Mix the initiator, dispersant, coupling agent, high-temperature resistant modifier and crosslinking point compound to obtain a high-temperature resistant modified premix; (2) React the high-temperature resistant modified premix obtained in step (1) with polyethylene, add a terminator, and dry to obtain high-temperature resistant modified particles. (3) The high-temperature resistant modified particles obtained in step (2) are mixed with the release agent and then screened to obtain high-temperature resistant modified powder; (4) The high-temperature resistant modified powder obtained in step (3) is mixed with the ethylene-vinyl alcohol copolymer to obtain the high-temperature resistant ethylene-vinyl alcohol copolymer.

10. The preparation method according to claim 9, characterized in that, The mixing temperature in step (1) is 20-120℃.

11. The preparation method according to claim 9, characterized in that, The mixing includes stirring.

12. The preparation method according to claim 11, characterized in that, The stirring rate is 400-1000 rpm.

13. The preparation method according to claim 9, characterized in that, The reaction described in step (2) includes extrusion.

14. The preparation method according to claim 13, characterized in that, The extrusion temperature is 120-200℃.

15. The preparation method according to claim 13, characterized in that, The extrusion rate is 10-150 rpm.

16. The preparation method according to claim 9, characterized in that, The drying time is 1-5 minutes.

17. The preparation method according to claim 9, characterized in that, The drying temperature is 90-120 ℃.

18. The preparation method according to claim 9, characterized in that, The initial temperature of the mixture in step (3) is 20-80 ℃.

19. The preparation method according to claim 9, characterized in that, The temperature after mixing in step (3) is 25-130℃.

20. The preparation method according to claim 9, characterized in that, Step (4) after mixing also includes extrusion, molding, cooling and settling.

21. The preparation method according to claim 20, characterized in that, The extrusion temperature is 120-300 ℃.

22. The preparation method according to claim 20, characterized in that, The molding temperature is 180-250 ℃.

23. The preparation method according to claim 20, characterized in that, The molding time is 5-10 minutes.

24. The preparation method according to claim 20, characterized in that, The cooling time is 5-10 minutes.

25. The preparation method according to claim 20, characterized in that, The settling time is 10-24 hours.

26. The preparation method according to claim 20, characterized in that, The settling temperature is 20-30 ℃.

27. The use of a high-temperature resistant ethylene-vinyl alcohol copolymer as described in any one of claims 1-8 in packaging materials, structural materials, textile materials or medical materials.

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