Polyethylene composition, process for its preparation, cable, use

Abstract

This invention relates to a polyethylene composition, its preparation method, cables, and applications. The polyethylene composition comprises high-density polyethylene and end-group double-bond polyethylene in a mass ratio of 1000:(1~100), wherein the end-group double-bond polyethylene has the structural formula [formula missing], and n is a positive integer from 10 to 200. Compared to high-density polyethylene, the above polyethylene composition has a high vinyl double bond content while having a relatively small impact on rheological properties.

Description

Technical Field

[0001] This invention relates to the field of polymer materials, and in particular to a polyethylene composition, its preparation method, cables, and applications. Background Technology

[0002] High-pressure polyethylene (HPPE), also known as low-density polyethylene (LDPE), is a branched polyethylene obtained by free radical polymerization of ethylene under high temperature and pressure. HPPE is a crucial raw material for the production of high-voltage cables. The molecular weight and its distribution, degree of branching, and types of double bonds in HPPE significantly impact the cable manufacturing process and service performance. Optimizing the structural parameters of HPPE is essential for the production of high-voltage cables.

[0003] In the cable manufacturing process, high-density polyethylene (HDPE) needs to be cross-linked with the help of additives to become cross-linked polyethylene (XLPE), thereby improving its heat resistance and meeting the heat resistance requirements of cables. However, residual additives after cross-linking will adversely affect the electrical performance of the cable. Optimizing the structure of HDPE to achieve a high degree of cross-linking while minimizing the amount of cross-linking additives is one of the important research directions for researchers.

[0004] Traditional high-density polyethylene (HDPE) produces a small amount of vinyl double bonds during ethylene polymerization, typically not exceeding 0.3 / 1000C (i.e., 0.3 vinyl double bonds per 1000 carbon atoms). Studies have shown that increasing the vinyl double bond content in HDPE can effectively improve its crosslinking efficiency and reduce the amount of crosslinking aids required. A conventional method involves free radical copolymerization of ethylene with a non-conjugated diene (such as 1,9-decadiene) under high temperature and pressure to prepare HDPE with a high vinyl double bond content. However, this method is technically challenging and involves certain crosslinking side reactions. Therefore, further research is needed on new HDPE methods with high vinyl double bond content. Summary of the Invention

[0005] Based on this, some embodiments of the present invention provide a polyethylene composition having a high vinyl double bond content.

[0006] In addition, some other embodiments of the present invention also provide a method for preparing a polyethylene composition, which can obtain high-pressure polyethylene with high vinyl double bond content through a simple and easy method, and reduce cross-linking side reactions during the preparation process.

[0007] Some embodiments of the present invention also provide a cable and its application.

[0008] A polyethylene composition comprising high-density polyethylene and end-group double-bond polyethylene in a mass ratio of 1000:(1~100), wherein the end-group double-bond polyethylene has the structural formula of [insert structural formula here]. n is a positive integer from 10 to 200.

[0009] In some embodiments, the mass ratio of the high-pressure polyethylene to the end-group double-bond polyethylene is 1000:(2~30).

[0010] In some embodiments, the number-average molecular weight of the end-group double-bond polyethylene is 300 g / mol to 2000 g / mol, and the molecular weight distribution is 1 to 10.

[0011] In some embodiments, the polyethylene composition further includes end-group saturated polyethylene, the end-group saturated polyethylene having the following structural formula: n is a positive integer from 10 to 200;

[0012] In the polyethylene composition, based on the total molar percentage of the terminal-saturated polyethylene and the terminal-double-bond polyethylene being 100%, the molar percentage of the terminal-double-bond polyethylene is greater than or equal to 80%.

[0013] Optionally, with the total molar percentage of the terminal-saturated polyethylene and the terminal-double-bonded polyethylene being 100%, the molar percentage of the terminal-double-bonded polyethylene is greater than or equal to 88%.

[0014] In some embodiments, the polyethylene composition satisfies one or more of the following conditions:

[0015] (1) The melt index of the polyethylene composition is 0.2 g / 10 min to 20 g / 10 min, and is 1% to 5% higher than that of the high-pressure polyethylene;

[0016] (2) In the high-pressure polyethylene, the content of vinyl double bonds per 1000 carbon atoms is less than or equal to 0.3, and in the polyethylene composition, the content of vinyl double bonds per 1000 carbon atoms is 0.2 to 1.0.

[0017] (3) The number average molecular weight of the polyethylene composition is 5000 g / mol to 100000 g / mol, and the molecular weight distribution is 1 to 10.

[0018] In some embodiments, the polyethylene composition satisfies one or more of the following conditions:

[0019] (1) The melt index of the polyethylene composition is 0.5 g / 10 min to 8 g / 10 min;

[0020] (2) In the polyethylene composition, the content of vinyl double bonds per 1000 carbon atoms is 0.3 to 0.8;

[0021] (3) The number average molecular weight of the polyethylene composition is 10000 g / mol to 50000 g / mol, and the molecular weight distribution is 3 to 6.

[0022] A method for preparing a polyethylene composition includes the following steps:

[0023] The polyethylene composition is prepared by melt blending high-pressure polyethylene and end-group double-bond polyethylene.

[0024] The mass ratio of the high-pressure polyethylene to the end-group double-bond polyethylene is 1000:(1~100), and the structural formula of the end-group double-bond polyethylene is as follows: n is a positive integer from 10 to 200.

[0025] In some embodiments, the melt blending temperature is 140°C to 230°C;

[0026] Optionally, the melt blending temperature is 160°C to 200°C.

[0027] In some embodiments, the step of melt blending high-pressure polyethylene and end-group double-bond polyethylene is carried out in an internal mixer for 3 to 60 minutes; or...

[0028] The step of melt blending high-pressure polyethylene and end-group double-bond polyethylene is carried out in a twin-screw extruder with an aspect ratio of 5 to 50.

[0029] A cable, the raw materials of which include the above-described polyethylene composition or a polyethylene composition prepared by the above-described preparation method.

[0030] The above-mentioned polyethylene composition includes a certain ratio of conventional high-pressure polyethylene and low-molecular-weight end-group double-bond polyethylene. The combination of the two can obtain high-pressure polyethylene with high vinyl double bond content and has little impact on the rheological properties of high-pressure polyethylene. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 The infrared spectra of the high-density polyethylene (LDPE) used in Example 1 and the prepared polyethylene composition (v-LDPE) are shown. Detailed Implementation

[0033] To facilitate understanding of the present invention, a more comprehensive description of the invention will be provided below in conjunction with specific embodiments. Preferred embodiments of the invention are given in the specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0035] Unless otherwise stated or in case of contradiction, the terms or phrases used in this invention shall have the following meanings:

[0036] In this invention, "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" and "second" may explicitly or implicitly include at least one of those features.

[0037] In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0038] In this invention, "one or several" refers to any one, any two, or any two or more of the listed items. "Several" refers to any two or more.

[0039] In this invention, unless otherwise specified, all percentage concentrations refer to the final concentration. The final concentration refers to the proportion of the added component in the system after the addition of that component.

[0040] The terms "preferred," "more preferably," etc., used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.

[0041] When a numerical range is disclosed in this invention, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Further, when the range refers to an integer, it includes every integer between the minimum and maximum values ​​of the range. Moreover, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed in this invention should be understood to include any and all subranges to which they are incorporated.

[0042] In this invention, the technical features described in an open-ended manner include both closed-ended technical solutions composed of the listed features and open-ended technical solutions that include the listed features.

[0043] The terms "comprising" and "having," and any variations thereof, used in embodiments of this invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or components inherent to such processes, methods, products, or devices.

[0044] In this invention, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0045] The first aspect of this application provides a polyethylene composition comprising: high-density polyethylene (LDPE) and v-PE with double bonds at mass ratios of 1000:(1~100), wherein the v-PE has the structural formula of [insert structural formula here]. n is a positive integer from 10 to 200.

[0046] In some embodiments, the mass ratio of low-density polyethylene (LDPE) to terminal double-bond polyethylene (v-PE) is 1000:(1~100). For example, the mass ratio of LDPE to v-PE may be, but is not limited to, 1000:1, 1000:2, 1000:5, 1000:8, 1000:10, 1000:12, 1000:15, 1000:18, 1000:20, 1000:22, 1000:25, 1000:28, 1000:30, 1000:40, 1000:50, 1000:60, 1000:70, 1000:80, 1000:90, 1000:100, or any range of two of these values. Preferably, the mass ratio of LDPE to v-PE is 1000:(2~30). If the v-PE content is too low, the vinyl double bond content in the polyethylene composition may be too low; if the v-PE content is too high, the macroscopic properties (such as mechanical properties and rheological properties) of the polyethylene composition may deteriorate.

[0047] In some embodiments, the melt index of high-density polyethylene (HDPE) is 0.2 g / 10 min to 20 g / 10 min. For example, the melt index of HDPE may be, but is not limited to, 0.2 g / 10 min, 0.5 g / 10 min, 1 g / 10 min, 1.5 g / 10 min, 2 g / 10 min, 3 g / 10 min, 4 g / 10 min, 5 g / 10 min, 6 g / 10 min, 7 g / 10 min, 8 g / 10 min, 10 g / 10 min, 12 g / 10 min, 15 g / 10 min, 18 g / 10 min, 20 g / 10 min, or a range of any two of these values. Preferably, the melt index of HDPE is 0.5 g / 10 min to 8 g / 10 min.

[0048] Melt flow index (MFR) refers to the amount of thermoplastic material extruded under specified conditions within a certain time period, i.e., the mass of melt passing through a standard die capillary every 10 minutes, expressed as MFR and measured in g / 10 min. It characterizes the viscous flow properties of thermoplastic materials in the molten state. At the aforementioned melt flow index, high-density polyethylene exhibits excellent rheological properties.

[0049] In some embodiments, the content of vinyl double bonds per 1000 carbon atoms in the high-density polyethylene is less than or equal to 0.3. For example, the content of vinyl double bonds per 1000 carbon atoms may be, but is not limited to, 0.3, 0.25, 0.2, 0.19, 0.18, 0.17, 0.16, 0.15, 0.14, 0.13, 0.12, 0.1, or a range of any two of these values.

[0050] It's understandable that high-density polyethylene can be obtained directly from the market.

[0051] In some embodiments, in end-group double-bond polyethylene, n is a positive integer from 10 to 200. For example, n is 10, 20, 50, 80, 100, 120, 150, 180, 200, or a range of any two of these values. For example, n is 10 to 50.

[0052] In some embodiments, the number-average molecular weight of the terminal double-bond polyethylene (v-PE) is 300 g / mol to 2000 g / mol, and the molecular weight distribution is 1 to 10. For example, the number-average molecular weight of v-PE may be, but is not limited to, 300 g / mol, 500 g / mol, 600 g / mol, 800 g / mol, 1000 g / mol, 1200 g / mol, 1400 g / mol, 1500 g / mol, 1600 g / mol, 1800 g / mol, 2000 g / mol, or any combination of these values. Optionally, the number-average molecular weight of v-PE is 500 g / mol to 1400 g / mol. The molecular weight distribution of v-PE can be, but is not limited to, 1, 1.2, 1.4, 1.5, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3, 4, 5, 6, 7, 8, 9, 10, or any combination of these values. Preferably, the molecular weight distribution of v-PE is 1.1 to 3.

[0053] In some embodiments, the polyethylene composition further includes end-group saturated polyethylene, the end-group saturated polyethylene having the following structural formula: n is a positive integer from 10 to 200;

[0054] In the polyethylene composition, with the total molar percentage of the terminal-saturated polyethylene and the terminal-double-bond polyethylene being 100%, the molar percentage of the terminal-double-bond polyethylene is greater than or equal to 80%. For example, the molar percentage of the terminal-double-bond polyethylene may be, but is not limited to, 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, 96%, or a range of any two of these values. Preferably, the molar percentage of the terminal-double-bond polyethylene is greater than or equal to 88%.

[0055] It is understandable that a small amount of end-group saturated polyethylene will be generated during the preparation of end-group double-bond polyethylene. Therefore, a small amount of end-group saturated polyethylene will still exist in the polyethylene composition.

[0056] In some embodiments, the melt index of the polyethylene composition is 0.2 g / 10 min to 20 g / 10 min. For example, the melt index of the polyethylene composition may be, but is not limited to, 0.2 g / 10 min, 0.5 g / 10 min, 1 g / 10 min, 1.5 g / 10 min, 2 g / 10 min, 3 g / 10 min, 4 g / 10 min, 5 g / 10 min, 6 g / 10 min, 7 g / 10 min, 8 g / 10 min, 10 g / 10 min, 12 g / 10 min, 15 g / 10 min, 18 g / 10 min, 20 g / 10 min, or any range of two of these values. Preferably, the melt index of the polyethylene composition is 0.5 g / 10 min to 8 g / 10 min. Within the above melt index range, the polyethylene composition exhibits excellent rheological properties.

[0057] In some embodiments, the melt index of the polyethylene composition is 1% to 5% higher than that of high-density polyethylene. Adding a certain amount of end-group double-bonded polyethylene to high-density polyethylene will slightly increase the melt index of the polyethylene composition, but has little overall impact on the rheological properties of high-density polyethylene.

[0058] In some embodiments, the vinyl double bond content in the polyethylene composition is 0.2 / 1000C to 1.0 / 1000C (i.e., the vinyl double bond content is 0.2 to 1.0 per 1000 carbon atoms). For example, the vinyl double bond content is 0.2 / 1000C, 0.3 / 1000C, 0.4 / 1000C, 0.5 / 1000C, 0.6 / 1000C, 0.7 / 1000C, 0.8 / 1000C, 0.9 / 1000C, 1 / 1000C, or any range of two of these values. Preferably, the vinyl double bond content in the polyethylene composition is 0.3 / 1000C to 0.8 / 1000C.

[0059] In some embodiments, the number-average molecular weight of the polyethylene composition is from 5000 g / mol to 100000 g / mol. For example, the number-average molecular weight of the polyethylene composition may be, but is not limited to, 5000 g / mol, 10000 g / mol, 15000 g / mol, 20000 g / mol, 25000 g / mol, 30000 g / mol, 35000 g / mol, 40000 g / mol, 45000 g / mol, 50000 g / mol, 60000 g / mol, 80000 g / mol, 10000 g / mol, or any range of two of these values. Preferably, the number-average molecular weight of the polyethylene composition is from 10000 g / mol to 50000 g / mol.

[0060] In some embodiments, the molecular weight distribution of the polyethylene composition is 1 to 10. For example, the molecular weight distribution of the polyethylene composition may be, but is not limited to, 1, 2, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, or any combination of these values. Preferably, the molecular weight distribution of the polyethylene composition is 3 to 6.

[0061] In some embodiments, the polyethylene composition further contains an antioxidant. In some embodiments, the mass ratio of antioxidant to high-density polyethylene is (2-20):1000. For example, the mass ratio of antioxidant to high-density polyethylene is 2:1000, 4:1000, 5:1000, 6:1000, 7:1000, 8:1000, 9:1000, 10:1000, 12:1000, 15:1000, 18:1000, 20:1000, or any range of two of these values. Optionally, the mass ratio of antioxidant to high-density polyethylene is (5-10):1000.

[0062] In a specific example, the antioxidant may be one or more commonly used in the art, such as, but not limited to, antioxidant 1010 and antioxidant 225.

[0063] The aforementioned polyethylene composition comprises a certain ratio of conventional high-density polyethylene (vinyl double bond content less than or equal to 0.3%) and low-molecular-weight end-group double-bond polyethylene. The combination of these two materials yields high-density polyethylene with a high vinyl double bond content, and has minimal impact on the rheological properties of the high-density polyethylene. In conventional methods, obtaining high-density polyethylene with a high vinyl double bond content typically involves adjusting the synthesis process of high-density polyethylene, which is technically challenging. However, in some embodiments of this application, a novel method for preparing high-density polyethylene with a high vinyl double bond content is provided by mixing existing high-density polyethylene with low-molecular-weight end-group double-bond polyethylene in a specific ratio.

[0064] Studies have shown that increasing the content of vinyl double bonds in high-voltage polyethylene can effectively improve the crosslinking efficiency of high-voltage polyethylene and reduce the amount of crosslinking aids. Therefore, the above-mentioned polyethylene composition, when applied to cables, can significantly improve the crosslinking efficiency of high-voltage polyethylene and reduce the amount of crosslinking aids, and has good application prospects in the production of high-voltage cables and other fields.

[0065] In addition, the above-mentioned polyethylene composition also has excellent mechanical properties.

[0066] A second aspect of this application provides a method for preparing a polyethylene composition, comprising the following steps:

[0067] The polyethylene composition is prepared by melt blending high-pressure polyethylene and end-group double-bond polyethylene.

[0068] The mass ratio of the high-pressure polyethylene to the end-group double-bond polyethylene is 1000:(1~100), and the structural formula of the end-group double-bond polyethylene is as follows: n is a positive integer from 10 to 200.

[0069] It is understood that the preparation process of high-density polyethylene is highly mature, controllable, and easy to implement in this field. It can be prepared by methods commonly used in this field or directly obtained from commercial products, and its specific preparation steps will not be provided here. Similarly, the preparation steps of end-group double-bond polyethylene are also described in this field, for example, the method described in reference Polym. Chem., 2014, 5, 105-115.

[0070] In some embodiments, the melt blending step is carried out under inert gas protection.

[0071] In some embodiments, the melt blending temperature is 140°C to 230°C. For example, the melt blending temperature may be, but is not limited to, 140°C, 150°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, 210°C, 230°C, or any combination of these values. Preferably, the melt blending temperature is 160°C to 200°C.

[0072] In some embodiments, melt blending is performed using an internal mixer or a twin-screw extruder.

[0073] In some embodiments, melt blending is performed in an internal mixer for a time ranging from 3 to 60 minutes. For example, the melt blending time may be 3 minutes, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes, or any range of these values. Optionally, the melt blending time may be 5 minutes to 30 minutes.

[0074] In other embodiments, melt blending is performed in a twin-screw extruder with an aspect ratio of 5 to 50. For example, the aspect ratio of the twin-screw extruder can be, but is not limited to, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, or any combination of these values. In a twin-screw extruder, mixing is achieved through screw extrusion; a high aspect ratio in a twin-screw extruder results in good mixing performance.

[0075] A traditional method for preparing high-vinyl-content high-pressure polyethylene (VLDPE) includes the following steps: free radical copolymerization of ethylene and a non-conjugated diene (such as 1,9-decadiene) under high temperature and pressure. Under these conditions, the non-conjugated diene and ethylene primarily undergo copolymerization, thereby introducing vinyl double bonds into the VLDPE side chains. The VLDPE obtained by this copolymerization method can have a vinyl double bond content of 0.4~0.8 / 1000C, which is significantly higher than that of ordinary VLDPE. However, this method involves optimizing the high-pressure polymerization process of ethylene, which is difficult to implement, and certain cross-linking side reactions occur during the copolymerization of the non-conjugated diene and ethylene. Therefore, it is essential to provide a simple and easy method for preparing high-vinyl-content VLDPE (v-LDPE) with reduced cross-linking side reactions for the preparation of high-voltage cables with excellent performance.

[0076] In the preparation method of the polyethylene composition of the present invention, high-density polyethylene (LDPE) and v-PE (v-PE) can be prepared separately using mature technical routes. A polyethylene composition with high and adjustable vinyl double bond content is obtained by blending the two in a certain ratio. The preparation process is simple, and there are no side reactions during the blending process. Compared with traditional methods, the above method has the following advantages: the preparation processes of LDPE and v-PE are highly mature, controllable, and easy to implement; the blending process of LDPE and v-PE is also a routine operation, easy to implement, and the process is relatively mature. Furthermore, there are no crosslinking side reactions during melt blending. Therefore, the above method provides a simple and easy method for preparing v-LDPE with adjustable vinyl double bonds, which is cost-effective, highly practical, and overcomes the disadvantages of traditional techniques, such as high operational difficulty and uncontrollable side reactions. The polyethylene composition prepared by the above method has a high vinyl double bond content. When applied to cables, it can significantly improve the crosslinking efficiency of high-density polyethylene and reduce the amount of crosslinking aids used, showing good application prospects in the production of high-voltage cables and other fields.

[0077] A third aspect of the present invention provides a cable, the raw materials of which include the above-described polyethylene composition or a polyethylene composition prepared by the above-described method.

[0078] It is understood that cables may also include other raw materials commonly used in the field, which can be obtained by those skilled in the art as needed, and the manufacturing process of cables is also relatively mature, so it will not be elaborated here.

[0079] A fourth aspect of the present invention provides the application of end-group double-bond polyethylene in the manufacture of cables, wherein the structural formula of the end-group double-bond polyethylene is as follows: Where n is a positive integer from 10 to 200. To make the objectives and advantages of this invention clearer, the polyethylene composition and its effects of this invention are further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only for explaining this invention and should not be used to limit this invention. Unless otherwise specified, the following embodiments do not include components other than unavoidable impurities. Unless otherwise specified, the drugs and instruments used in the embodiments are conventional choices in the art. Experimental methods not specified in the embodiments are implemented according to conventional conditions, such as those described in literature, books, or methods recommended by the manufacturer.

[0080] Example 1

[0081] This embodiment provides a polyethylene composition comprising: 4000 parts by weight of high-density polyethylene (purchased from Sinopec Qilu Petrochemical J182A, with a vinyl double bond content of 0.18 / 1000C and a melt index of 1.95 g / 10 min), and a mixture of 50 parts by weight of end-group double-bond polyethylene and end-group saturated polyethylene (n = 43, number average molecular weight M). n =1200g / mol, PDI=1.5, the molar percentage of end-group double-bonded polyethylene is 92%, prepared according to the literature Polym. Chem., 2014, 5, 105-115) and 20 parts by mass of antioxidant 1010.

[0082] The preparation steps of the polyethylene composition in this embodiment are as follows:

[0083] In a 5L interlocking internal mixer, 4000 parts by weight of high-pressure polyethylene (purchased from Sinopec Qilu Petrochemical J182A, vinyl double bond content 0.18 / 1000C, melt index 1.95 g / 10min) and 50 parts by weight of a mixture of end-group double-bond polyethylene and end-group saturated polyethylene (n=43, number average molecular weight M) were added. n =1200 g / mol, PDI=1.5, the molar percentage of end-group double-bond polyethylene is 92% (prepared according to the literature Polym. Chem., 2014, 5, 105-115), and 20 parts by mass of antioxidant 1010, are mixed at 160°C for 25 minutes under a nitrogen atmosphere and a rotation speed of 30 rpm. After mixing, high-density polyethylene (v-LDPE) with high vinyl double bond content is obtained, which is the polyethylene composition of this embodiment.

[0084] Infrared spectroscopy showed that the vinyl double bond content of the obtained v-LDPE was 0.31 / 1000C. Melt index analysis showed that the v-LDPE had a melt index of 2.0 g / 10 min. This indicates that the polyethylene composition prepared in Example 1, by mixing high-pressure polyethylene and end-group double-bond polyethylene in a certain proportion, significantly increased the vinyl double bond content from 0.18 / 1000C to 0.31 / 1000C compared to high-pressure polyethylene, thus significantly increasing the vinyl double bond content. Simultaneously, the melt index increased from 1.95 g / 10 min to 2.0 g / 10 min, a 2.6% increase, but the change in melt index was small and had minimal impact on rheological properties.

[0085] The infrared spectra of the high-density polyethylene (LDPE) used in Example 1 and the prepared polyethylene composition (v-LDPE) are shown below. Figure 1 As shown. Figure 1 In the diagram, the lower curve corresponds to LDPE, and the upper curve corresponds to v-LDPE. Figure 1 In the diagram, the horizontal axis represents the wavenumber, and the vertical axis T represents the transmittance.

[0086] Example 2

[0087] This embodiment provides a polyethylene composition comprising: 4000 parts by weight of high-density polyethylene (purchased from Sinopec Qilu Petrochemical 2100TN00, vinyl double bond content of 0.15 / 1000C, melt index of 7.2 g / 10min), and a mixture of 120 parts by weight of terminal double bond polyethylene and terminal saturated polyethylene (n = 25, number average molecular weight M). n =700g / mol, PDI=1.3, the molar percentage of end-group double-bonded polyethylene is 95%, prepared according to the literature Polym. Chem., 2014, 5, 105-115) and 20 parts by mass of antioxidant 1010.

[0088] The preparation steps of the polyethylene composition in this embodiment are as follows:

[0089] In a 5L interlocking internal mixer, 4000 parts by weight of high-pressure polyethylene (purchased from Sinopec Qilu Petrochemical 2100TN00, vinyl double bond content 0.15 / 1000C, melt index 7.2 g / 10min) and a total of 120 parts by weight of a mixture of end-group double-bond polyethylene and end-group saturated polyethylene (n=25, number average molecular weight M) were added. n=700 g / mol, PDI=1.3, the molar percentage of end-group double-bond polyethylene is 95% (prepared according to the literature Polym. Chem., 2014, 5, 105-115), and 20 parts by mass of antioxidant 1010, are mixed at 150°C for 20 minutes under a nitrogen atmosphere and a rotation speed of 40 rpm. After mixing, high-density polyethylene (v-LDPE) with high vinyl double bond content is obtained, which is the polyethylene composition of this embodiment.

[0090] Infrared spectroscopy showed that the vinyl double bond content of the obtained v-LDPE was 0.42 / 1000C. Melt index analysis showed that the v-LDPE had a melt index of 7.5 g / 10 min. This indicates that the polyethylene composition prepared in Example 2, by mixing high-pressure polyethylene and end-group double-bond polyethylene in a certain proportion, increased the vinyl double bond content from 0.15 / 1000C to 0.42 / 1000C compared to high-pressure polyethylene, thus increasing the vinyl double bond content. Simultaneously, the melt index increased from 7.2 g / 10 min to 7.5 g / 10 min, a 4.2% increase, but the change in melt index was small and had minimal impact on rheological properties.

[0091] Example 3

[0092] This embodiment provides a polyethylene composition comprising: 16,000 parts by weight of high-density polyethylene (purchased from Sinopec Qilu Petrochemical J182B, with a vinyl double bond content of 0.19 / 1000C and a melt index of 2.0 g / 10 min), a total of 400 parts by weight of a mixture of end-group double-bond polyethylene and end-group saturated polyethylene (n = 21, number-average molecular weight Mn = 580 g / mol, PDI = 1.2, and the molar percentage of end-group double-bond polyethylene is 96%, prepared according to the literature Polym. Chem., 2014, 5, 105-115), and 50 parts by weight of antioxidant 225.

[0093] The preparation steps of the polyethylene composition in this embodiment are as follows:

[0094] In a 25L high-speed mixer, 16,000 parts by mass of high-density polyethylene (purchased from Sinopec Qilu Petrochemical J182B, vinyl double bond content 0.19 / 1000C, melt index 2.0 g / 10min), a mixture of 400 parts by mass of terminal double bond polyethylene and terminal saturated polyethylene (n=21, number average molecular weight Mn=580 g / mol, PDI=1.2, molar percentage of terminal double bond polyethylene 96%, prepared according to literature Polym. Chem., 2014, 5, 105-115), and 50 parts by mass of antioxidant 225 were added. The mixture was kneaded at room temperature for 3 minutes under a nitrogen atmosphere. The resulting material was extruded using a twin-screw extruder, cooled, pelletized, and dried to obtain high-density polyethylene (v-LDPE) with high vinyl double bond content, which is the polyethylene composition of this embodiment. The extrusion conditions were: screw speed 20 rpm, and temperatures of zones one through five of 160℃, 170℃, 180℃, 180℃, and 170℃, respectively.

[0095] Infrared spectroscopy showed that the vinyl double bond content of the obtained v-LDPE was 0.71 / 1000C. Melt index analysis showed that the melt index of v-LDPE was 2.1 g / 10 min.

[0096] It can be seen that the polyethylene composition prepared in Example 3, by mixing high-pressure polyethylene and end-group double-bond polyethylene in a certain proportion, increases the vinyl double bond content from 0.19 / 1000C to 0.71 / 1000C compared to high-pressure polyethylene, thus increasing the vinyl double bond content; at the same time, the melt index changes from 2.0 g / 10 min to 2.1 g / 10 min, an increase of 5%, and the change in melt index is not significant, so it has little impact on rheological properties.

[0097] Example 4

[0098] This embodiment provides a polyethylene composition comprising: 4000 parts by weight of high-density polyethylene (purchased from Sinopec Qilu Petrochemical J182A, with a vinyl double bond content of 0.18 / 1000C and a melt index of 1.95 g / 10 min), and a mixture of 320 parts by weight of end-group double-bond polyethylene and end-group saturated polyethylene (n = 43, number average molecular weight M). n =1200g / mol, PDI=1.5, the molar percentage of end-group double-bonded polyethylene is 92%, prepared according to the literature Polym. Chem., 2014, 5, 105-115) and 20 parts by mass of antioxidant 1010.

[0099] The preparation steps of the polyethylene composition are the same as in Example 1, and will not be repeated here.

[0100] Infrared spectroscopy showed that the vinyl double bond content of the obtained v-LDPE was 0.9 / 1000C. Melt index analysis showed that the melt index of v-LDPE was 2.9 g / 10 min. This indicates that the polyethylene composition prepared in Example 4, by mixing high-pressure polyethylene and end-group double-bond polyethylene in a certain proportion, significantly increased the vinyl double bond content from 0.18 / 1000C to 0.9 / 1000C compared to high-pressure polyethylene; simultaneously, the melt index changed only slightly from 1.95 g / 10 min to 2.9 g / 10 min, having little impact on rheological properties.

[0101] Example 5

[0102] This embodiment provides a polyethylene composition comprising: 4000 parts by weight of high-density polyethylene (purchased from Sinopec Qilu Petrochemical J182A, with a vinyl double bond content of 0.18 / 1000C and a melt index of 1.95 g / 10 min), and a mixture of 50 parts by weight of end-group double-bond polyethylene and end-group saturated polyethylene (n = 186, number average molecular weight M). n =4830 g / mol, PDI=2.5, the molar percentage of end-group double-bonded polyethylene is 92%, prepared according to the literature Polym. Chem., 2014, 5, 105-115) and 20 parts by mass of antioxidant 1010.

[0103] The preparation steps of the polyethylene composition are the same as in Example 1, and will not be repeated here.

[0104] Infrared spectroscopy showed that the vinyl double bond content of the obtained v-LDPE was 0.23 / 1000C. Melt index analysis showed that the melt index of v-LDPE was 2.02 g / 10 min. This indicates that the polyethylene composition prepared in Example 5, by mixing high-pressure polyethylene and end-group double-bond polyethylene in a certain proportion, increased the vinyl double bond content from 0.18 / 1000C to 0.23 / 1000C compared to high-pressure polyethylene, thus increasing the vinyl double bond content. Simultaneously, the melt index changed only slightly from 1.95 g / 10 min to 2.02 g / 10 min, having a minimal impact on rheological properties.

[0105] Comparative Example 1

[0106] Comparative Example 1 provides a polyethylene composition comprising: 4000 parts by weight of high-density polyethylene (purchased from Sinopec Qilu Petrochemical J182A, with a vinyl double bond content of 0.18 / 1000C and a melt index of 1.95 g / 10 min), and a mixture of 50 parts by weight of end-group double-bond polyethylene and end-group saturated polyethylene (n = 471, number average molecular weight M). n=13200g / mol, PDI=2.2, the molar percentage of end-group double-bonded polyethylene is 84%, prepared according to the literature Polym. Chem., 2014, 5, 105-115) and 20 parts by mass of antioxidant 1010.

[0107] The preparation steps of the polyethylene composition are the same as in Example 1, and will not be repeated here.

[0108] Infrared spectroscopy showed that the vinyl double bond content of the obtained v-LDPE was 0.19 / 1000C. Melt index analysis showed that the melt index of v-LDPE was 1.98 g / 10 min.

[0109] As can be seen from Comparative Example 1, the number-average molecular weight of the end-group double-bond polyethylene is too large. Compared with high-pressure polyethylene, the vinyl double bond content of the prepared polyethylene composition increased from 0.18 / 1000C to 0.19 / 1000C, but the vinyl double bond content did not change much.

[0110] Comparative Example 2

[0111] Comparative Example 2 provides a polyethylene composition comprising: 4000 parts by weight of high-density polyethylene (purchased from Sinopec Qilu Petrochemical J182A, with a vinyl double bond content of 0.18 / 1000C and a melt index of 1.95 g / 10 min), and a mixture of 800 parts by weight of end-group double-bond polyethylene and end-group saturated polyethylene (n = 43, number average molecular weight M). n =1200g / mol, PDI=1.5, the molar percentage of end-group double-bonded polyethylene is 92%, prepared according to the literature Polym. Chem., 2014, 5, 105-115) and 20 parts by mass of antioxidant 1010.

[0112] The preparation steps of the polyethylene composition are the same as in Example 1, and will not be repeated here.

[0113] Infrared spectroscopy showed that the vinyl double bond content of the obtained v-LDPE was 1.9 / 1000C. Melt index analysis showed that the melt index of v-LDPE was 13.0 g / 10 min.

[0114] As can be seen from the comparison between Comparative Example 2 and Example 1, the increased content of end-group double-bond polyethylene will increase the vinyl double bond content in the prepared polyethylene composition (from 0.18 / 1000C to 1.9 / 1000C), but at the same time, it will also cause the melt index of the prepared polyethylene composition (13.0 g / 10 min) to be 567% higher than that of the raw material high-pressure polyethylene (melt index of 1.95 g / 10 min). The significant increase in melt index has a great impact on rheological properties.

[0115] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0116] The embodiments described above are merely illustrative of several implementations of the present invention, designed to facilitate a detailed understanding of the technical solutions of the present invention, but should not be construed as limiting the scope of protection of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided by the present invention through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this invention patent should be determined by the content of the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. A polyethylene composition, characterized in that, It is composed of high-pressure polyethylene, end-group double-bond polyethylene, end-group saturated polyethylene, and antioxidant; the mass ratio of the high-pressure polyethylene to the end-group double-bond polyethylene is 1000:(2~30), and the structural formula of the end-group double-bond polyethylene is as follows: n is a positive integer from 10 to 50; the structural formula of the end-group saturated polyethylene is n is a positive integer from 10 to 50; in the polyethylene composition, the molar percentage of the end-group saturated polyethylene and the end-group double-bond polyethylene is greater than or equal to 80% based on a total molar percentage of 100%; the mass ratio of the antioxidant to the high-pressure polyethylene is (2~20):1000.

2. The polyethylene composition according to claim 1, characterized in that, The mass ratio of the high-pressure polyethylene to the end-group double-bond polyethylene is 1000:(10~30).

3. The polyethylene composition according to claim 1, characterized in that, The number-average molecular weight of the end-group double-bond polyethylene is 500 g / mol to 1400 g / mol, and the molecular weight distribution is 1 to 10.

4. The polyethylene composition according to claim 1, characterized in that, With the total molar percentage of the terminal saturated polyethylene and the terminal double bond polyethylene being 100%, the molar percentage of the terminal double bond polyethylene is greater than or equal to 88%.

5. The polyethylene composition according to any one of claims 1 to 4, characterized in that, The polyethylene composition satisfies one or more of the following conditions: (1) The melt index of the polyethylene composition is 0.2 g / 10 min to 20 g / 10 min, and is 1% to 5% higher than that of the high-pressure polyethylene; (2) In the high-pressure polyethylene, the content of vinyl double bonds per 1000 carbon atoms is less than or equal to 0.3, and in the polyethylene composition, the content of vinyl double bonds per 1000 carbon atoms is 0.2 to 1.

0. (3) The number average molecular weight of the polyethylene composition is 5000 g / mol to 100000 g / mol, and the molecular weight distribution is 1 to 10.

6. The polyethylene composition according to claim 5, characterized in that, The polyethylene composition satisfies one or more of the following conditions: (1) The melt index of the polyethylene composition is 0.5 g / 10 min to 8 g / 10 min; (2) In the polyethylene composition, the content of vinyl double bonds per 1000 carbon atoms is 0.3 to 0.8; (3) The number average molecular weight of the polyethylene composition is 10000 g / mol to 50000 g / mol, and the molecular weight distribution is 3 to 6.

7. A method for preparing a polyethylene composition according to any one of claims 1 to 6, characterized in that, Includes the following steps: The polyethylene composition is prepared by melt blending high-pressure polyethylene, end-group double-bond polyethylene, end-group saturated polyethylene and an antioxidant. The mass ratio of the high-pressure polyethylene to the end-group double-bond polyethylene is 1000:(2~30), and the structural formula of the end-group double-bond polyethylene is as follows: n is a positive integer from 10 to 50; The structural formula of the end-group saturated polyethylene is as follows: n is a positive integer from 10 to 50; In the polyethylene composition, based on the total molar percentage of the terminal-saturated polyethylene and the terminal-double-bond polyethylene being 100%, the molar percentage of the terminal-double-bond polyethylene is greater than or equal to 80%. The mass ratio of the antioxidant to the high-pressure polyethylene is (2~20):1000.

8. The method for preparing the polyethylene composition according to claim 7, characterized in that, The melt blending temperature is 140℃~230℃.

9. The method for preparing the polyethylene composition according to claim 8, characterized in that, The melt blending temperature is 160℃~200℃.

10. The method for preparing the polyethylene composition according to any one of claims 7 to 9, characterized in that, The step of melt blending high-pressure polyethylene and end-group double-bond polyethylene is carried out in an internal mixer for 3 to 60 minutes; or... The step of melt blending high-pressure polyethylene and end-group double-bond polyethylene is carried out in a twin-screw extruder with an aspect ratio of 5 to 50.

11. A cable, characterized in that, The raw materials for preparation include the polyethylene composition according to any one of claims 1 to 6 or the polyethylene composition prepared by the preparation method according to any one of claims 7 to 10.

12. The use of a polyethylene composition in the manufacture of cables, characterized in that, The polyethylene composition is the polyethylene composition according to any one of claims 1 to 6 or includes a polyethylene composition prepared by the preparation method according to any one of claims 7 to 10.

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