Low-temperature-resistant polyethylene, preparation method thereof and 3PE anticorrosive coating

Abstract

The invention relates to the technical field of high polymer materials, in particular to low-temperature-resistant polyethylene, a preparation method thereof and a 3PE anticorrosive coating. The low-temperature-resistant polyethylene is prepared from the following components in parts by weight: 50 to 80 parts of PERT resin, 10 to 40 parts of olefin block copolymer, 0 to 30 parts of metallocene linear low-density polyethylene, 1 to 3 parts of anti-ultraviolet filler and 0.3 to 1 part of antioxidant. The polyethylene provided by the invention has good processability, the notched impact strength at-45 DEG C can reach 100 kJ / m < 2 > or above, the notched impact strength at-60 DEG C can reach 95 kJ / m < 2 > at most, and the polyethylene has excellent low temperature resistance. The lower limit of the use temperature of a 3PE anti-corrosion pipeline can be reduced to-60 DEG C or below by adopting a 3PE anti-corrosion layer prepared from the polyethylene, so that the stability of the 3PE anti-corrosion pipeline in low-temperature operation is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, in particular to low-temperature resistant polyethylene, a preparation method thereof, and a 3PE anti-corrosion layer. Background Art

[0002] The 3PE anti-corrosion layer of steel pipe is composed of a fused epoxy powder base layer, an adhesive middle layer and an outer polyethylene anti-corrosion layer. These three layers are organically combined into a whole, and the bottom epoxy powder layer is firmly bonded to the steel pipe substrate, so that the coating has the advantages of fused epoxy powder coating and polyethylene coating. The fused epoxy powder mainly forms ionic bonds and physical intercalation forces through the action of its active groups with the activated ions on the surface of the steel pipe, so that it firmly adheres to the surface of the metal group. The role of the adhesive middle layer is to organically combine the bottom fused epoxy powder and the outer polyethylene layer, protecting the bottom fused epoxy from external erosion. [ .

[0003] With the development of pipelines, more and more pipelines are required to operate in cold external environments, with operating temperatures dropping from -30°C to -50 to -60°C. This requires improved low-temperature resistance for anti-corrosion pipelines. The better the low-temperature resistance of the polyethylene in the pipeline anti-corrosion coating, the greater the stability of the anti-corrosion pipeline during transportation and use at low temperatures, thereby preventing the brittle cracking of the polyethylene caused by low temperatures, which would affect the anti-corrosion effectiveness. In addition, anti-corrosion steel pipes will inevitably be bumped and scratched during use in low-temperature environments. The anti-corrosion polyethylene must have sufficient toughness at low temperatures to keep damage within acceptable limits. Therefore, improving the low-temperature resistance of 3PE anti-corrosion pipelines is urgent.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide a low-temperature resistant polyethylene and a preparation method thereof and a 3PE anti-corrosion layer. The polyethylene of the present invention has excellent low-temperature resistance and a notched impact strength of up to 95 kJ / m at -60 ° C. 2 , which can reduce the lower operating temperature of 3PE anti-corrosion pipes to below -60°C, greatly improving the stability of 3PE anti-corrosion pipes under low-temperature operation.

[0006] In order to achieve the above-mentioned object of the present invention, the first aspect of the present invention provides a low-temperature resistant polyethylene, comprising the following components in parts by weight: 50-80 parts of PERT resin, 10-40 parts of olefin block copolymer, 0-30 parts of metallocene linear low-density polyethylene, 1-3 parts of anti-ultraviolet filler and 0.3-1 part of antioxidant.

[0007] In a specific embodiment of the present invention, the PERT resin includes at least one of PERT type I resin and PERT type II resin.

[0008] In a specific embodiment of the present invention, the PERT resin includes PERT type I resin and PERT type II resin. Furthermore, the mass ratio of the PERT type I resin to the PERT type II resin is 1: (0.5-2).

[0009] In a specific embodiment of the present invention, the olefin block copolymer includes at least one of Infuse 9010, Infuse 9817, Infuse 9107, Infuse 9530, Infuse 9100, Infuse 9507, Infuse 9007, Infuse 9077, Infuse 9000, Infuse 9807 and Infuse 9900.

[0010] In a specific embodiment of the present invention, the mass ratio of the PERT resin to the olefin block copolymer is (1.25-3.5):1.

[0011] In a specific embodiment of the present invention, the density of the metallocene linear low-density polyethylene is 0.91 to 0.93 g / cm 3 , the melt index at 190℃ / 2.16kg is 0.1~4g / 10min.

[0012] In a specific embodiment of the present invention, the melt flow rate of the low-temperature resistant polyethylene at 190° C. / 2.16 kg is ≥0.49 g / 10 min.

[0013] In a specific embodiment of the present invention, the low-temperature resistant polyethylene has a notched impact strength of ≥110 kJ / m at -45°C. 2 The low temperature resistant polyethylene has a notched impact strength of ≥70 kJ / m at -60 °C. 2 .

[0014] The second aspect of the present invention provides a method for preparing the low-temperature resistant polyethylene of the first aspect of the present invention, comprising the following steps: mixing, extruding and granulating the ingredients of the low-temperature resistant polyethylene of the first aspect of the present invention.

[0015] The third aspect of the present invention provides a 3PE anti-corrosion layer, comprising a polyethylene anti-corrosion layer; the polyethylene anti-corrosion layer is mainly made of the low-temperature resistant polyethylene of the first aspect of the present invention.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) The polyethylene of the present invention has good processing properties and a notched impact strength of up to 100 kJ / m at -45°C. 2 Above, the notched impact strength at -60℃ can reach up to 95kJ / m 2 , has excellent low temperature resistance; (2) The 3PE anti-corrosion layer made of the polyethylene of the present invention can reduce the lower limit of the operating temperature of the 3PE anti-corrosion pipeline to below -60°C, greatly improving the stability of the 3PE anti-corrosion pipeline under low-temperature operation. DETAILED DESCRIPTION

[0017] The technical scheme of the present invention will be clearly and completely described below in conjunction with specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work premise belong to the scope of protection of the present invention. Those who do not specify specific conditions in the embodiments are carried out according to normal conditions or the conditions recommended by the manufacturer. Those whose reagents or instruments are not specified by the manufacturer are conventional products that can be purchased commercially.

[0018] With the development of pipeline industry, the industry has put forward higher requirements for low temperature impact resistance of polyethylene materials. For example, the notched impact strength at -60℃ needs to be ≥65kJ / m 2 At present, the notched impact strength of ordinary anti-corrosion polyethylene at -60°C is much lower than this, only reaching about 10 to 20 kJ / m 2 Notched impact strength.

[0019] There are two types of polyethylene used for corrosion protection. One is to use high-density polyethylene as the main material, combined with metallocene polyethylene and ethylene propylene rubber for toughening. However, the low-temperature resistance cannot meet the current notched impact strength requirements at -60°C. The other method is to use high-density polyethylene and metallocene polyethylene as the main materials, combined with the introduction of peroxides to cross-link the polyethylene to form a cross-linked network structure to achieve the effect of improving toughness. However, this method introduces antioxidants and peroxides at the same time. On the one hand, the processing is difficult to control and the stability is poor. On the other hand, peroxides will consume antioxidants and affect the aging resistance of the material. Another method is to use oil-filled SEBS and SEPS for toughening. Although there is a certain toughening effect, the oil-filled SEBS and SEPS will leak oil during long-term use. The oil will migrate to the adhesive and epoxy interface, affecting the bonding strength and thus the service life of the corrosion-resistant pipeline.

[0020] Based on this, the first aspect of the present invention provides low-temperature resistant polyethylene, including the following components by weight: 50 to 80 parts of PERT resin, 10 to 40 parts of olefin block copolymer, 0 to 30 parts of metallocene linear low-density polyethylene, 1 to 3 parts of anti-ultraviolet filler and 0.3 to 1 part of antioxidant.

[0021] PERT resin is a polyethylene material with excellent heat resistance. The inventors of this invention discovered in their research that the presence of numerous and longer side chains in PERT resin facilitates entanglement between molecular chains, thereby improving the material's low-temperature impact strength. Its low-temperature impact resistance is superior to that of Grade 100 polyethylene pipe. Furthermore, the addition of a certain amount of olefin block copolymer can achieve a low-temperature toughening effect, superior to conventional toughening agents such as EPDM, POE, and SBS. This low-temperature toughening effect is achieved while avoiding a decrease in the Vicat softening point. Conventional toughening agents, however, significantly reduce the Vicat softening point, impacting the performance of polyethylene used for corrosion protection.

[0022] The polyethylene of the present invention has good processing performance and its notched impact strength at -45°C can reach 100 kJ / m 2 Above, the notched impact strength at -60℃ can reach up to 95kJ / m 2 , with excellent low temperature resistance and suitable Vicat softening point.

[0023] For example, in different embodiments, the amounts of the components in the low-temperature resistant polyethylene can be as follows, calculated by weight: The amount of PERT resin can be 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts or a range consisting of any two thereof; The amount of the olefin block copolymer can be 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts or a range consisting of any two thereof; The amount of metallocene linear low-density polyethylene can be 0 parts, 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts or a range consisting of any two thereof; The amount of the anti-ultraviolet filler can be 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts or a range consisting of any two thereof; The amount of the antioxidant can be 0.3 parts, 0.5 parts, 0.8 parts, 1 part or a range consisting of any two of them.

[0024] In a specific embodiment of the present invention, the PERT resin includes at least one of a PERT I resin and a PERT II resin. The combination of PERT I and PERT II resins facilitates the entanglement between chain segments within the molecular structure, significantly improving the low-temperature impact resistance and processing properties of the polyethylene.

[0025] In a specific embodiment of the present invention, the PERT resin includes a PERT I resin and a PERT II resin. Furthermore, the mass ratio of the PERT I resin to the PERT II resin is 1:(0.5-2), for example, 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2, or any combination thereof. This helps to improve both the low-temperature impact resistance and processing properties of the low-temperature resistant polyethylene.

[0026] In a specific embodiment of the present invention, the olefin block copolymer includes at least one of Infuse 9010, Infuse 9817, Infuse 9107, Infuse 9530, Infuse 9100, Infuse 9507, Infuse 9007, Infuse 9077, Infuse 9000, Infuse 9807, and Infuse 9900. The olefin block copolymer is an olefin block copolymer (OBC) synthesized by The Dow Chemical Company using a chain-shuttling polymerization process. The inventors of the present invention have discovered that the OBC contains amorphous ethylene-octene segments with low glass transition temperatures, combined with the chain-shuttling process, resulting in unexpected improvements in the low-temperature performance of polyethylene. This significantly enhances the low-temperature impact strength of polyethylene without reducing its Vicat softening point and eliminating the risk of oil leakage.

[0027] In a specific embodiment of the present invention, the mass ratio of PERT resin to olefin block copolymer is (1.25-3.5):1, for example, it can be 1.25:1, 1.5:1, 1.8:1, 2:1, 2.5:1, 3:1, 3.5:1 or a range composed of any two thereof, thereby further taking into account both improving low-temperature impact resistance and ensuring a suitable Vicat softening point.

[0028] In a specific embodiment of the present invention, the density of the metallocene linear low-density polyethylene is 0.91 to 0.93 g / cm 3 , for example, it can be 0.91 g / cm 3 、0.915g / cm 3 , 0.92g / cm 3 , 0.925g / cm 3 , 0.93g / cm3 Or a range consisting of any two thereof; the melt index under 190°C / 2.16kg conditions is 0.1 to 4g / 10min, for example, it can be 0.1g / 10min, 1g / 10min, 2g / 10min, 3g / 10min, 4g / 10min or a range consisting of any two thereof.

[0029] In a specific embodiment of the present invention, the UV-resistant filler comprises titanium dioxide and / or carbon black. Furthermore, the UV-resistant filler is titanium dioxide treated with a silane coupling agent and / or carbon black treated with a silane coupling agent, with the carbon black having a particle size of ≤30 nm. The titanium dioxide comprises rutile titanium dioxide. The addition of an appropriate amount of UV-resistant filler can resist ultraviolet rays, reduce sunlight damage to pipelines, and extend the service life of anti-corrosion pipelines.

[0030] In a specific embodiment of the present invention, the antioxidant includes, but is not limited to, at least one of Antioxidant 1010, Antioxidant 168, and Antioxidant B245. UV absorbers, light stabilizers, and the like may also be added. The addition of antioxidants can reduce the degradation of polyethylene during processing and increase the material's oxidation induction period, improving its thermal and light aging resistance, thereby effectively extending the service life of the anti-corrosion pipeline.

[0031] In a specific embodiment of the present invention, the melt flow rate of the low-temperature resistant polyethylene at 190°C / 2.16kg is ≥0.49g / 10min, for example, it can be 0.49g / 10min, 0.5g / 10min, 0.52g / 10min, 0.55g / 10min, 0.58g / 10min, 0.6g / 10min or a range composed of any two of them, thereby ensuring good processability of the low-temperature resistant polyethylene of the present invention.

[0032] In a specific embodiment of the present invention, the low-temperature resistant polyethylene has a notched impact strength of ≥110 kJ / m at -45°C. 2 , for example, it can be 110kg / m 2 、115kg / m 2 , 120kg / m 2 、125kg / m 2 、130kg / m 2 、135kg / m 2 Or the range of any two of them; low temperature resistant polyethylene notched impact strength at -60℃ ≥70kJ / m 2 , for example, it can be 70kg / m 2 , 75kg / m 2 、80kg / m 2 、85kg / m 2 , 90kg / m2 , 95kg / m 2 Or the range of any two of them, thereby reducing the lower limit of the use temperature of the 3PE anti-corrosion layer made of the polyethylene material of the present invention to below -60°C, thereby improving the stability of the 3PE anti-corrosion pipeline under low-temperature operation.

[0033] In a specific embodiment of the present invention, the Vicat softening point of the low-temperature resistant polyethylene is 110-120°C.

[0034] The second aspect of the present invention provides a method for preparing the low-temperature resistant polyethylene of the first aspect of the present invention, comprising the following steps: mixing, extruding and granulating the ingredients of the low-temperature resistant polyethylene of the first aspect of the present invention.

[0035] In a specific embodiment of the present invention, the temperature during extrusion granulation is 190-220° C. Extrusion granulation is performed using a twin-screw extruder, and conventional extrusion granulation parameters can be set.

[0036] The third aspect of the present invention provides a 3PE anti-corrosion layer, comprising a polyethylene anti-corrosion layer; the polyethylene anti-corrosion layer is mainly made of the low-temperature resistant polyethylene of the first aspect of the present invention.

[0037] Example 1 This embodiment provides low-temperature resistant polyethylene, which includes the following components in parts by weight: 67 parts of PERT resin, 20 parts of olefin block copolymer, 10 parts of metallocene linear low-density polyethylene, 2.2 parts of anti-ultraviolet filler and 0.8 parts of antioxidant.

[0038] The PEPR resin is a mixture of PERT I resin and PERT II resin in a mass ratio of 1:1, wherein the PERT I resin is Dow Chemical PE-RT 2344 and the PERT II resin is Dow Chemical PE-RT 2388; the olefin block copolymer is Infuse 9010 produced by Dow Chemical in the United States; the density of the metallocene linear low-density polyethylene is 0.918 g / cm 3 , 190℃ / 2.16kg melt index is 1g / 10min; the UV-resistant filler is carbon black treated with silane coupling agent, with a carbon black particle size of less than 30nm (Cabot PE6336); The antioxidant is a mixture of antioxidant 1010, antioxidant 168, anti-ultraviolet absorber UV-531, light stabilizer UV944 and antioxidant 245 in a mass ratio of 1:1:1:1:1.

[0039] This embodiment provides a method for preparing low-temperature-resistant polyethylene, comprising the following steps: weighing the components according to the above proportions, mixing them uniformly in a high-speed mixer, and then extruding and granulating them using a twin-screw extruder to obtain polyethylene pellets. The twin-screw extruder parameters include: extruder zone 1: 160°C, zone 2: 200°C, zone 3: 230°C, zone 4: 230°C, zone 5: 230°C, zone 6: 230°C, zone 7: 230°C, zone 8: 230°C, die: 220°C, main engine speed: 300 RPM, and feed rate: 10 Hz.

[0040] Example 2 This embodiment refers to the low-temperature resistant polyethylene and its preparation method of Example 1, with the only difference being that the amounts of the components are different.

[0041] The low-temperature resistant polyethylene of this embodiment includes the following components in parts by weight: 67 parts of PERT resin, 10 parts of olefin block copolymer, 20 parts of metallocene linear low-density polyethylene, 2.2 parts of anti-ultraviolet filler and 0.8 parts of antioxidant.

[0042] Example 3 This embodiment refers to the low-temperature resistant polyethylene and its preparation method of Example 1, with the only difference being that the amounts of the components are different.

[0043] The low-temperature resistant polyethylene of this embodiment includes the following components in parts by weight: 57 parts of PERT resin, 40 parts of olefin block copolymer, 2.2 parts of anti-ultraviolet filler and 0.8 parts of antioxidant.

[0044] Example 4 This embodiment refers to the low-temperature resistant polyethylene and its preparation method of Example 1, with the only difference being that the amounts of the components are different.

[0045] The low-temperature resistant polyethylene of this embodiment includes the following components in parts by weight: 50 parts of PERT resin, 20 parts of olefin block copolymer, 27 parts of metallocene linear low-density polyethylene, 2.2 parts of anti-ultraviolet filler and 0.8 parts of antioxidant.

[0046] Example 5 This embodiment refers to the low-temperature resistant polyethylene and its preparation method of Example 1, with the only difference being that the amounts of the components are different.

[0047] The low-temperature resistant polyethylene of this embodiment includes the following components in parts by weight: 80 parts of PERT resin, 17 parts of olefin block copolymer, 2.2 parts of anti-ultraviolet filler and 0.8 parts of antioxidant.

[0048] Example 6 This embodiment refers to the low-temperature resistant polyethylene and its preparation method of Example 3, with the only difference being that the ratio of PERT I resin to PERT II resin in the PEPR resin is different.

[0049] In the low-temperature resistant polyethylene of this embodiment, the PEPR resin is a mixture of PERT I resin and PERT II resin in a mass ratio of 1:0.5.

[0050] Example 7 This embodiment refers to the low-temperature resistant polyethylene and its preparation method of Example 3, with the only difference being that the ratio of PERT I resin to PERT II resin in the PEPR resin is different.

[0051] In the low-temperature resistant polyethylene of this embodiment, the PEPR resin is a mixture of PERT I resin and PERT II resin in a mass ratio of 1:2.

[0052] Example 8 This embodiment refers to the low-temperature resistant polyethylene and its preparation method of Example 3, with the only difference being that only PERT I type resin is used in the PEPR resin.

[0053] Example 9 This embodiment refers to the low-temperature resistant polyethylene and its preparation method of Example 3, with the only difference being that only PERT II type resin is used in the PEPR resin.

[0054] Example 10 This embodiment refers to the low-temperature resistant polyethylene and its preparation method of Example 1, with the only difference being that the amounts of the components are different.

[0055] The low-temperature resistant polyethylene of this embodiment includes the following components in parts by weight: 75 parts of PERT resin, 22 parts of olefin block copolymer, 2.2 parts of anti-ultraviolet filler and 0.8 parts of antioxidant.

[0056] Comparative Example 1 Comparative Example 1 refers to the low-temperature resistant polyethylene and its preparation method of Example 1, except that the components and amounts are different.

[0057] The polyethylene of Comparative Example 1 comprises the following components in parts by weight: 20 parts of olefin block copolymer, 10 parts of metallocene linear low-density polyethylene, 67 parts of high-density polyethylene, 2.2 parts of anti-ultraviolet filler and 0.8 parts of antioxidant.

[0058] The high-density polyethylene is a grade 100 polyethylene pipe material with a melt index of 0.2 g / 10 min (190° C., 5 kg). Others are the same as in Example 1.

[0059] Comparative Example 2 Comparative Example 2 refers to the low-temperature resistant polyethylene and its preparation method of Example 1, except that the components and amounts are different.

[0060] The polyethylene of Comparative Example 2 comprises the following components by weight: 67 parts of PERT resin, 10 parts of metallocene linear low-density polyethylene, 20 parts of EPDM rubber, 2.2 parts of anti-ultraviolet filler, and 0.8 parts of antioxidant. The rest is the same as in Example 1.

[0061] Comparative Example 3 Comparative Example 3 refers to the low-temperature resistant polyethylene and its preparation method of Example 1, except that the components and amounts are different.

[0062] The polyethylene of Comparative Example 3 includes the following components in parts by weight: 60 parts of high-density polyethylene, 10 parts of metallocene linear low-density polyethylene, 30 parts of EPDM rubber, 5 parts of anti-ultraviolet filler, 0.8 parts of antioxidant and 0.15 parts of lubricant.

[0063] The high-density polyethylene is a grade 100 polyethylene pipe material with a melt index of 0.2 g / 10 min (190° C., 5 kg); the anti-ultraviolet filler is Cabot PE6336; the antioxidant is B215; the lubricant is zinc stearate; and the metallocene linear low-density polyethylene is the same as in Example 1.

[0064] Comparative Example 4 Comparative Example 4 refers to the low-temperature resistant polyethylene and its preparation method of Example 1, except that the components and amounts are different.

[0065] The polyethylene of Comparative Example 4 includes the following components in parts by weight: 30 parts of high-density polyethylene, 70 parts of metallocene linear low-density polyethylene, 0.2 parts of organic peroxide, 2 parts of polyethylene wax, 5 parts of anti-ultraviolet filler and 0.5 parts of antioxidant.

[0066] The high-density polyethylene is a grade 100 polyethylene pipe material with a melt index of 0.2 g / 10 min (190° C., 5 kg); the organic peroxide is 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane; the polyethylene wax is a homopolymer polyethylene wax; the UV-resistant filler is Cabot PE6336; the antioxidant is B215; and the metallocene linear low-density polyethylene is the same as in Example 1.

[0067] Comparative Example 5 Comparative Example 5 refers to the low-temperature resistant polyethylene and its preparation method of Example 1, except that the components and amounts are different.

[0068] The polyethylene of Comparative Example 5 includes the following components in parts by weight: 80 parts of high-density polyethylene, 10 parts of SEPS, 10 parts of plasticizer, 0.6 parts of antioxidant and 0.2 parts of ultraviolet absorber.

[0069] Among them, the high-density polyethylene is a grade 100 polyethylene pipe material with a melt index of 0.2g / 10min (190°C, 5Kg); the SEPS is Kraton G1701; the plasticizer is white oil; the antioxidant is B215; and the ultraviolet absorber is UV-531.

[0070] Experimental example The properties of the polyethylene materials of different embodiments and comparative examples were tested as follows, and the test results are shown in Table 1.

[0071] Melt flow rate: The melt flow rate is tested at 190°C / 2.16kg. The test method is in accordance with GB / T 3682-2018. Vicat softening point: The test method is carried out in accordance with GB / T 1633-2000; Oxidation induction period: carried out in accordance with GB / T23257-2017, test temperature 220℃; Notched Charpy Impact Strength: Tested in accordance with GB / T 1043.1-2008 after being kept at -45°C and -60°C for 24 hours. Oil leakage test: Place the granules obtained by granulation in a 50℃ oven for 30 days and observe the oil leakage.

[0072] Table 1 Test results of different polyethylene materials

[0073] From the above test results, it can be seen that the polyethylene of the present invention has good processing performance and its notched impact strength at -45°C can reach 100kJ / m 2 Above, up to 135kJ / m 2 The notched impact strength at -60°C can reach up to 95kJ / m 2 , with excellent low temperature resistance.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. Low temperature resistant polyethylene, characterized in that: It comprises the following components in parts by weight: 50-80 parts of PERT resin, 10-40 parts of olefin block copolymer, 0-30 parts of metallocene linear low-density polyethylene, 1-3 parts of anti-ultraviolet filler and 0.3-1 part of antioxidant.

2. The low-temperature resistant polyethylene according to claim 1, characterized in that The PERT resin includes at least one of PERT type I resin and PERT type II resin.

3. The low-temperature resistant polyethylene according to claim 1, characterized in that The PERT resin includes PERT type I resin and PERT type II resin.

4. The low-temperature resistant polyethylene according to claim 3, characterized in that The mass ratio of the PERT I resin to the PERT II resin is 1:(0.5-2).

5. The low-temperature resistant polyethylene according to claim 1, characterized in that: The olefin block copolymer includes at least one of Infuse 9010, Infuse 9817, Infuse 9107, Infuse 9530, Infuse 9100, Infuse 9507, Infuse 9007, Infuse 9077, Infuse 9000, Infuse 9807, and Infuse 9900.

6. The low-temperature resistant polyethylene according to claim 1, characterized in that The mass ratio of the PERT resin to the olefin block copolymer is (1.25-3.5):

1.

7. The low-temperature resistant polyethylene according to claim 1, characterized in that: The density of the metallocene linear low-density polyethylene is 0.91 to 0.93 g / cm 3 , the melt index at 190℃ / 2.16kg is 0.1~4g / 10min.

8. The low-temperature resistant polyethylene according to claim 1, characterized in that: Has at least one of the following characteristics: (1) The melt flow rate of the low-temperature resistant polyethylene at 190°C / 2.16kg is ≥0.49g / 10min; (2) The notched impact strength of the low-temperature resistant polyethylene at -45°C is ≥110 kJ / m 2 ; (3) The notched impact strength of the low-temperature resistant polyethylene at -60°C is ≥70 kJ / m 2 .

9. The method for preparing low-temperature resistant polyethylene according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: weighing each component in proportion, mixing, and extruding to form granules. 10.3PE anti-corrosion layer, characterized by: It comprises a polyethylene anti-corrosion layer; the polyethylene anti-corrosion layer is mainly made of the low-temperature resistant polyethylene described in any one of claims 1 to 8.

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