A pipe lining resin and its preparation method

Abstract

This invention belongs to the field of resin materials technology. This invention provides a pipe lining resin and its preparation method, which includes the following steps: S1, vacuum drying nylon 6 to obtain dried nylon; S2, mixing 19.5-20.5 parts by weight of the dried nylon, 4.9-5.2 parts by weight of compatibilizer, 68-72 parts by weight of medium-density polyethylene, 1.4-1.6 parts by weight of modified graphite nanosheets, and 3.4-3.6 parts by weight of maleic anhydride-grafted ethylene-octene copolymer to obtain a mixture; S3, melt-extruding the mixture in a twin-screw extruder, water-cooling and pelletizing, and vacuum drying to obtain the pipe lining resin. This invention improves the heat resistance and resistance to hot oil corrosion of the prepared pipe lining resin by limiting the amount of compatibilizer added to medium-density polyethylene and increasing the amount of nylon 6, while further improving its impact strength.

Description

Technical Field

[0001] This invention belongs to the field of resin materials technology, specifically relating to a pipe lining resin and its preparation method. Background Technology

[0002] In the selection of materials for the inner lining of oil pipelines, medium-density polyethylene (MDPE) has become a commonly used material due to its advantages such as corrosion resistance, wear resistance, non-scaling properties, and long service life. However, this material has shortcomings such as poor heat resistance, significant creep, and insufficient resistance to hot oil corrosion. Given that some scenarios in oil transportation operations require localized heating of the transported medium, the pipeline lining material must possess excellent heat resistance and resistance to hot oil corrosion.

[0003] Currently, to improve the heat resistance and resistance to hot oil corrosion of pipe lining materials, a common technique is to incorporate a compatibilizer and nylon 6 into medium-density polyethylene (MDPE) and prepare a blend through a compounding process. When the compatibilizer content remains constant (e.g., approximately 5%), the amount of nylon 6 used is positively correlated with the heat resistance and resistance to hot oil corrosion of the blend; specifically, this manifests as an increase in heat distortion temperature and a decrease in hot oil absorption rate.

[0004] However, at the same time, as the amount of nylon 6 used increases, the impact strength of the blend shows a downward trend. Summary of the Invention

[0005] To address the problems existing in the background art, the present invention provides a pipe lining resin and its preparation method. By limiting the amount of compatibilizer added to medium-density polyethylene and increasing the amount of nylon 6, the heat resistance and hot oil corrosion resistance of the prepared pipe lining resin are improved, while its impact strength is further enhanced.

[0006] To achieve the above objectives, in a first aspect, the present invention provides a method for preparing a pipe lining resin, comprising the following steps: S1. Vacuum dry nylon 6 to obtain dried nylon; S2. By weight, 19.5-20.5 parts of the dried nylon, 4.9-5.2 parts of the compatibilizer, 68-72 parts of medium-density polyethylene, 1.4-1.6 parts of modified graphite nanosheets and 3.4-3.6 parts of maleic anhydride-grafted ethylene-octene copolymer are mixed to obtain a mixture. S3. After the mixture is melt-extruded in a twin-screw extruder, it is water-cooled, pelletized, and vacuum-dried to obtain the pipe lining resin.

[0007] Furthermore, the modified graphite nanosheets are prepared as follows: A1. After ultrasonic oscillation treatment of graphite nanosheets with mixed acid, centrifugation, washing to neutrality, and drying to constant weight are performed to obtain acidified graphite nanosheets. A2. Take 9.5-10g of the acidified graphite nanosheets obtained in A1, prepare an initial slurry of 0.1wt% with ethanol solution, control the temperature at 60±2℃, add 0.45-0.5g of γ-aminopropyltriethoxysilane and 0.45-0.5g of lauryl alcohol polyoxyethylene ether, stir, and obtain the terminal slurry. A3. After filtration, the terminal slurry obtained in A2 is dried to obtain the modified graphite nanosheets.

[0008] Furthermore, in A1, the mixed acid is prepared by mixing nitric acid and sulfuric acid in a volume ratio of 1:3.

[0009] Furthermore, in A1, the ultrasonic oscillation frequency is 20 kHz, and the ultrasonic oscillation time is 3-4 hours.

[0010] Furthermore, in A2, the stirring speed is 950-11000 r / min, and the stirring time is 2-2.5 h.

[0011] Furthermore, in A3, the drying temperature is 80±2℃ and the drying time is 2-2.5h.

[0012] Furthermore, the specific operation of S1 is as follows: Nylon 6 is placed in a vacuum drying oven and vacuum dried for 8-10 hours at a temperature of 105±2℃ and a vacuum degree of -0.095MPa.

[0013] Furthermore, the compatibilizer is a polyolefin graft.

[0014] Secondly, the present invention provides a pipe lining resin, which is prepared by the above-described preparation method.

[0015] This application has the following beneficial effects: 1. In the preparation of the pipe lining resin of the present invention, maleic anhydride-grafted ethylene-octene copolymer and modified graphite nanosheets are introduced; the ethylene-octene soft segment of the maleic anhydride-grafted ethylene-octene copolymer provides high elasticity and excellent notched impact toughness; the polar groups of maleic anhydride can react with the amino and hydroxyl groups of nylon 6, and can also entangle with medium-density polyethylene, while forming hydrogen bonds with the hydroxyl / amino groups of modified graphite, thereby improving the notched impact strength of the prepared pipe lining resin.

[0016] 2. Maleic anhydride-grafted ethylene-octene copolymers flexibly disperse and bridge the two phases of medium-density polyethylene and nylon 6 through chemical reaction and physical entanglement, weakening / eliminating the stress concentration caused by the modified graphite nanosheets, and transforming the modified graphite nanosheets from "increased rigidity and embrittlement" to "increased strength and toughness", while maintaining heat resistance and oil resistance, and synergistically improving the notched impact strength. Attached Figure Description

[0017] Figure 1 This is a comparative trend chart of the heat distortion temperature and hot oil absorption rate test data of the samples prepared in Examples 1-3 and Comparative Examples 1-5 of the present invention. Figure 2 This is a comparative trend chart of the notched impact strength test data of the samples prepared in Examples 1-3 and Comparative Examples 1-5 of the present invention. Detailed Implementation

[0018] The present application will be further described in detail below with reference to the embodiments.

[0019] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application are all commercially available.

[0020] The preparation method of the modified graphite nanosheets involved in the embodiments / comparative examples of this invention is as follows: A1. Graphite nanosheets (5 mL: 1 g) were subjected to ultrasonic oscillation with a mixed acid at a frequency of 20 kHz for 3.5 h. Then, the nanosheets were centrifuged at 4000 r / min for 10 min to separate the bottom layer of graphite nanosheet suspension. The suspension was washed repeatedly with water until the pH value of the suspension was 7. The suspension was then dried at 80 °C to constant weight to obtain acidified graphite nanosheets.

[0021] The mixed acid is prepared by mixing nitric acid and sulfuric acid in a volume ratio of 1:3.

[0022] A2. Take 9.8g of the acidified graphite nanosheets obtained in A1, prepare an initial slurry of 0.1wt% with ethanol solution, control the temperature at 60℃, add 0.48g of γ-aminopropyltriethoxysilane and 0.47g of lauryl alcohol polyoxyethylene ether, stir at 10000r / min for 2h to obtain the terminal slurry.

[0023] A3. After filtration, the terminal slurry obtained in A2 is dried at 80°C for 2 hours to obtain modified graphite nanosheets.

[0024] The nylon 6 involved in the embodiments / comparative examples of this invention is B40LN from BASF, Germany.

[0025] The compatibilizer polyolefin graft material involved in the embodiments / comparative examples of this invention is GPM100A from Ningbo Nengzhiguang New Materials Co., Ltd.

[0026] The medium-density polyethylene used in the embodiments / comparative examples of this invention is 8818YL-CF from Dow Chemical Company, USA.

[0027] Example 1: A method for preparing a pipe lining resin, comprising the following steps: S1. Vacuum dry nylon 6 to obtain dried nylon; Specifically, nylon 6 was placed in a vacuum drying oven and vacuum dried for 9 hours at a temperature of 105℃ and a vacuum degree of -0.095MPa to obtain dried nylon.

[0028] S2. By weight, 20 parts of the dried nylon, 5 parts of the compatibilizer polyolefin graft, 70 parts of medium-density polyethylene, 1.5 parts of modified graphite nanosheets and 3.5 parts of maleic anhydride grafted ethylene-octene copolymer (Dow POE-g-MAH N525) are mixed to obtain a mixture.

[0029] S3. The mixture is melt-extruded in a twin-screw extruder. The temperature range of the twin-screw extruder is set sequentially to 235℃ / 235℃ / 240℃ / 240℃ / 235℃ / 230℃ / 220℃, and the screw speed is 160r / min. Then, it is water-cooled, pelletized, and vacuum-dried to obtain the pipe lining resin.

[0030] Example 2: The difference between this example and Example 1 is that: a method for preparing a pipe lining resin includes the following steps: S1. Vacuum dry Nylon 6 to obtain dried Nylon.

[0031] S2. By weight, 19.5 parts of the dried nylon, 4.9 parts of the compatibilizer polyolefin graft, 68 parts of medium-density polyethylene, 1.4 parts of modified graphite nanosheets and 3.4 parts of maleic anhydride-grafted ethylene-octene copolymer are mixed to obtain a mixture.

[0032] S3. After the mixture is melt-extruded in a twin-screw extruder, it is water-cooled, pelletized, and vacuum-dried to obtain the pipe lining resin.

[0033] Example 3: The difference between this example and Example 1 is that: a method for preparing a pipe lining resin includes the following steps: S1. Vacuum dry Nylon 6 to obtain dried Nylon.

[0034] S2. By weight, 20.5 parts of the dried nylon, 5.2 parts of the compatibilizer polyolefin graft, 72 parts of medium-density polyethylene, 1.6 parts of modified graphite nanosheets and 3.6 parts of maleic anhydride-grafted ethylene-octene copolymer are mixed to obtain a mixture.

[0035] S3. After the mixture is melt-extruded in a twin-screw extruder, it is water-cooled, pelletized, and vacuum-dried to obtain the pipe lining resin.

[0036] Comparative Example 1: The difference between this comparative example and Example 1 is that the modified graphite nanosheets and maleic anhydride-grafted ethylene-octene copolymer are both replaced with medium-density polyethylene; and 4 parts of the dried nylon are also replaced with medium-density polyethylene.

[0037] Specifically, a method for preparing a pipe lining resin includes the following steps: S1. Vacuum dry Nylon 6 to obtain dried Nylon.

[0038] S2. By weight, 16 parts of the dried nylon, 5 parts of the compatibilizer polyolefin graft and 79 parts of medium-density polyethylene are mixed to obtain a mixture.

[0039] S3. After the mixture is melt-extruded in a twin-screw extruder, it is water-cooled, pelletized, and vacuum-dried to obtain the pipe lining resin.

[0040] Comparative Example 2: The difference between this comparative example and Example 1 is that the modified graphite nanosheets and maleic anhydride-grafted ethylene-octene copolymer are both replaced with medium-density polyethylene; and 2 parts of the dried nylon are also replaced with medium-density polyethylene.

[0041] Specifically, a method for preparing a pipe lining resin includes the following steps: S1. Vacuum dry Nylon 6 to obtain dried Nylon.

[0042] S2. By weight, 18 parts of the dried nylon, 5 parts of the compatibilizer polyolefin graft and 77 parts of medium-density polyethylene are mixed to obtain a mixture.

[0043] S3. After the mixture is melt-extruded in a twin-screw extruder, it is water-cooled, pelletized, and vacuum-dried to obtain the pipe lining resin.

[0044] Comparative Example 3: The difference between this comparative example and Example 1 is that the modified graphite nanosheets and maleic anhydride-grafted ethylene-octene copolymer are both replaced with medium-density polyethylene.

[0045] Specifically, a method for preparing a pipe lining resin includes the following steps: S1. Vacuum dry Nylon 6 to obtain dried Nylon.

[0046] S2. By weight, 20 parts of the dried nylon, 5 parts of the compatibilizer polyolefin graft and 75 parts of medium-density polyethylene are mixed to obtain a mixture.

[0047] S3. After the mixture is melt-extruded in a twin-screw extruder, it is water-cooled, pelletized, and vacuum-dried to obtain the pipe lining resin.

[0048] Comparative Example 4: The difference between this comparative example and Example 1 is that maleic anhydride-grafted ethylene-octene copolymers are all replaced with medium-density polyethylene.

[0049] Specifically, a method for preparing a pipe lining resin includes the following steps: S1. Vacuum dry Nylon 6 to obtain dried Nylon.

[0050] S2. By weight, 20 parts of the dried nylon, 5 parts of the compatibilizer polyolefin graft, 73.5 parts of medium-density polyethylene and 1.5 parts of modified graphite nanosheets are mixed to obtain a mixture.

[0051] S3. After the mixture is melt-extruded in a twin-screw extruder, it is water-cooled, pelletized, and vacuum-dried to obtain the pipe lining resin.

[0052] Comparative Example 5: The difference between this comparative example and Example 1 is that the modified graphite nanosheets are replaced with medium-density polyethylene. Specifically, a method for preparing a pipe lining resin includes the following steps: S1. Vacuum dry Nylon 6 to obtain dried Nylon.

[0053] S2. By weight, 20 parts of the dried nylon, 5 parts of the compatibilizer polyolefin graft, 71.5 parts of medium-density polyethylene and 3.5 parts of maleic anhydride grafted ethylene-octene copolymer are mixed to obtain a mixture.

[0054] S3. After the mixture is melt-extruded in a twin-screw extruder, it is water-cooled, pelletized, and vacuum-dried to obtain the pipe lining resin.

[0055] Test Example: Test Subjects: Samples prepared in Examples 1-3 and Comparative Examples 1-5. Test Items and Methods: ① Heat Deflection Temperature: A standard sample of 120mm × 15mm × 10mm was measured using a heat distortion and Vicat softening point temperature tester at a pressure of 0.45MPa; ② Hot Oil Absorption Rate: A 2mm thick sample was vacuum dried, cooled, and weighed to constant weight. It was then immersed in a mixture of gasoline and xylene (volume ratio 2:3) at 80℃ for 24 hours, dried, weighed, and the oil absorption rate was calculated; ③ Notched Impact Strength: Refer to GB / T 1843-2008 "Determination of Impact Strength of Plastic Cantilever Beams". Test Results: See Table 1.

[0056] Table 1. Experimental Data Results Analysis: Combining the data in Table 1 and... Figures 1-2Analysis of Examples 1-3 shows that the pipe lining resin prepared by the present invention (Examples 1-3) exhibits a heat distortion temperature exceeding 80.1℃, a hot oil absorption rate below 8.8%, and a notched impact strength of 17.1 kJ / m. 2 above.

[0057] Combining the data in Table 1 and Figures 1-2 Analysis of Example 1 and Comparative Examples 1-5: Specifically, by comparing Comparative Examples 1, 2, and 3, it can be seen that without adding modified graphite nanosheets and maleic anhydride-grafted ethylene-octene copolymer, as the amount of dried nylon added increases (mass percentage 16%→20%), the heat distortion temperature of the pipe lining resin increases, and the hot oil absorption rate decreases. That is, the heat resistance and hot oil corrosion resistance increase with the increase of the amount of dried nylon added (mass percentage 16%→20%); however, the notched impact strength decreases accordingly.

[0058] Specifically, by comparing Comparative Examples 3 and 4, it can be seen that, compared with Comparative Example 3, Comparative Example 4, by simply adding the modified graphite nanosheets prepared by the present invention, resulted in improved heat resistance and resistance to hot oil corrosion of the pipe lining resin. However, the notched impact strength was further reduced.

[0059] This is mainly because, when the modified graphite nanosheets prepared by this invention are added alone, on the one hand, the modified graphite nanosheets can further improve the heat distortion temperature and heat-resistant oil permeability of the prepared pipe lining resin, maintaining or even strengthening the original advantageous properties; on the other hand, the modified graphite nanosheets are too rigid and are prone to becoming stress concentration points, which only increases rigidity but not toughness, and instead leads to a further reduction in impact strength.

[0060] Specifically, by comparing Comparative Example 3 and Comparative Example 5, it can be seen that, compared with Comparative Example 3, Comparative Example 5, by simply introducing maleic anhydride-grafted ethylene-octene copolymer, resulted in a significant improvement in the notched impact strength of the pipe lining resin.

[0061] In comparison with Example 1, it can be seen that the simultaneous introduction of modified graphite nanosheets and maleic anhydride-grafted ethylene-octene copolymer can produce a synergistic effect, thereby synergistically improving the notched impact strength of the prepared pipe lining resin.

[0062] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0063] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for preparing a pipe lining resin, characterized in that, Includes the following steps: S1. Vacuum dry nylon 6 to obtain dried nylon; S2. By weight, 19.5-20.5 parts of the dried nylon, 4.9-5.2 parts of the compatibilizer, 68-72 parts of medium-density polyethylene, 1.4-1.6 parts of modified graphite nanosheets and 3.4-3.6 parts of maleic anhydride-grafted ethylene-octene copolymer are mixed to obtain a mixture. S3. After the mixture is melt-extruded in a twin-screw extruder, it is water-cooled, pelletized, and vacuum-dried to obtain the pipe lining resin.

2. The method for preparing pipe lining resin according to claim 1, characterized in that, The modified graphite nanosheets are prepared as follows: A1. After ultrasonic oscillation treatment of graphite nanosheets with mixed acid, centrifugation, washing to neutrality, and drying to constant weight are performed to obtain acidified graphite nanosheets. A2. Take 9.5-10g of the acidified graphite nanosheets obtained in A1, prepare an initial slurry of 0.1wt% with ethanol solution, control the temperature at 60±2℃, add 0.45-0.5g of γ-aminopropyltriethoxysilane and 0.45-0.5g of lauryl alcohol polyoxyethylene ether, stir, and obtain the terminal slurry. A3. After filtration, the terminal slurry obtained in A2 is dried to obtain the final product.

3. The method for preparing pipe lining resin according to claim 2, characterized in that, In A1, the mixed acid is prepared by mixing nitric acid and sulfuric acid in a volume ratio of 1:

3.

4. The method for preparing pipe lining resin according to claim 2, characterized in that, In A1, the ultrasonic oscillation frequency is 20 kHz, and the ultrasonic oscillation time is 3-4 hours.

5. The method for preparing pipe lining resin according to claim 2, characterized in that, In A2, the stirring speed is 950-11000 r / min, and the stirring time is 2-2.5 h.

6. The method for preparing pipe lining resin according to claim 2, characterized in that, In A3, the drying temperature is 80±2℃ and the drying time is 2-2.5h.

7. The method for preparing pipe lining resin according to claim 1, characterized in that, The specific operation of S1 is as follows: Nylon 6 is vacuum dried for 8-10 hours at a temperature of 105±2℃ and a vacuum degree of -0.095MPa.

8. The method for preparing pipe lining resin according to claim 1, characterized in that, The compatibilizer is a polyolefin graft.

9. A pipe lining resin, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 8.

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