Modified polypropylene-based insulating material and preparation method thereof

Abstract

The invention discloses a modified polypropylene-based insulating material and a preparation method thereof, and belongs to the technical field of high polymer materials, the modified polypropylene-based insulating material comprises the following raw materials by weight: 90-110 parts of antioxidant polypropylene, 4-6 parts of a heat stabilizer, 18-24 parts of a modified insulating stabilizer, and 1-3 parts of a beta nucleating agent; the antioxidant polypropylene is an antioxidant 3052 grafted polypropylene; the anti-oxidation polypropylene with good heat aging resistance is introduced, the insulation aging phenomenon of an insulation layer is effectively improved, the direct current dielectric property of the polypropylene-based insulation material is improved, in addition, the modified insulation stabilizer with good compatibility is introduced, meanwhile, the polypropylene-based material is endowed with good strength and insulativity, and the service life of the polypropylene-based insulation material is prolonged. The breakdown phenomenon of the insulating layer is effectively avoided, and the service life of the polypropylene-based insulating material is prolonged through the synergistic effect of the polypropylene-based insulating material and the insulating layer.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a modified polypropylene-based insulating material and a preparation method thereof. Background Art

[0002] Polypropylene-based insulation material is a polymer material with polypropylene as the main component. It has excellent electrical insulation properties and good chemical stability and is widely used in power cables, communication cables and other fields.

[0003] However, on the one hand, polypropylene will show the phenomenon of being brittle at low temperatures, and on the other hand, the conductor will generate heat when carrying current, causing the polypropylene-based insulating material to be in a high temperature and high electric field environment for a long time, accelerating the thermal aging performance of the polypropylene-based material. At the same time, under the action of the DC electric field, a large amount of space charge accumulation will occur in the insulating material, causing current breakdown, and reducing the service life of the polypropylene-based insulating material. Therefore, how to improve the insulation aging performance of the polypropylene-based insulating material, enhance its electrical resistance and resistance to low temperature brittleness, and improve its service life is a technical problem that needs to be solved at present. Summary of the invention

[0004] The object of the present invention is to provide a modified polypropylene-based insulating material and a preparation method thereof, so as to solve the problems in the background technology.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A modified polypropylene-based insulating material comprises the following raw materials in parts by weight:

[0007] 90-110 parts of antioxidant polypropylene, 4-6 parts of heat stabilizer, 18-24 parts of modified insulation stabilizer, 1-3 parts of β nucleating agent; the antioxidant polypropylene is antioxidant 3052 grafted polypropylene;

[0008] The modified insulating stabilizer is obtained by the following steps:

[0009] Add the modified elastomer and 2,4-dihydroxybenzophenone to tetrahydrofuran, mix well, add concentrated sulfuric acid, react at 65-70° C. for 9-10 hours, cool, place in deionized water and stand for 15 minutes, centrifuge to retain the precipitate, and dry to obtain a modified insulating stabilizer;

[0010] Furthermore, the dosage ratio of tetrahydrofuran, modified elastomer, 2,4-dihydroxybenzophenone, concentrated sulfuric acid and deionized water is 200mL: 8-13g: 19-23g: 1.8mL: 400mL; wherein, 2,4-dihydroxybenzophenone is used as a reaction monomer, concentrated sulfuric acid is used as a catalyst, and phenolic hydroxyl groups are reacted with an acid anhydride in the modified elastomer to undergo an esterification reaction to obtain a carboxyl-containing aromatic ketone modified insulating stabilizer, wherein the aromatic group has a lower ionization potential and a higher electron affinity, is easily excited or ionized to capture electrons, absorbs the energy of high-energy electrons to reduce the kinetic energy and number of electrons, and has good insulating properties.

[0011] Furthermore, the modified elastomer is prepared by the following steps:

[0012] A1. Add hydrogenated styrene-butadiene block copolymer and dioctyl phthalate to maleic anhydride, perform melt reaction at 230-240° C. for 1.5-3 hours, and then cool and dry to obtain an intermediate;

[0013] A2. Add the intermediate to dichloromethane, stir and dissolve at 75°C, cool to room temperature, add acetyl chloride, mix well, add anhydrous aluminum chloride, stir and react for 2-3.5h, and then purify, filter and dry to obtain a modified elastomer;

[0014] Among them, hydrogenated styrene-butadiene block copolymer, as an olefin elastomer, has good compression deformation performance and mechanical strength. Under the action of the catalyst dioctyl phthalate, the tertiary carbon atoms on its molecular chain segment are grafted with maleic anhydride to obtain an intermediate. Then, acetyl chloride is used as an acylation agent and anhydrous aluminum chloride is used as a catalyst to directly modify the acetophenone unit on the styrene chain segment of the intermediate through a Friedel-Crafts acylation reaction to obtain an acetylated modified elastomer containing maleic anhydride grafting.

[0015] Furthermore, the usage ratio of maleic anhydride, hydrogenated styrene-butadiene block copolymer and dioctyl phthalate is 9-12 g: 10-11 g: 0.5 mL.

[0016] Furthermore, the usage ratio of dichloromethane, intermediate, acetyl chloride and anhydrous aluminum chloride is 300mL:10-12g:6-7mL:0.6-1g.

[0017] Furthermore, the purification treatment is to place it in excess methanol for precipitation, filter, dry, then dissolve it in dichloromethane at 50°C, and then place it in excess methanol for precipitation, and repeat the operation multiple times.

[0018] Furthermore, the antioxidant polypropylene is prepared by the following steps:

[0019] Add antioxidant 3052 and diisopropylbenzene peroxide to polypropylene, melt react at 180-190°C for 1-2h, cool and dry, place in xylene, dissolve and reflux at 138°C, cool, place in acetone for precipitation, filter and dry to obtain antioxidant polypropylene;

[0020] Among them, antioxidant 3052, as a hindered phenol antioxidant containing a carbon-carbon double bond in the molecular chain, can not only quench active free radicals, but also the polar group phenolic hydroxyl group can introduce local energy levels in the polyolefin band gap as a charge trap, capture carriers, and effectively inhibit charge transport. It has good insulation aging resistance. Under the action of the initiator diisopropylbenzene peroxide, it undergoes melt free radical grafting with polypropylene through the carbon-carbon double bond to obtain antioxidant polypropylene.

[0021] Furthermore, the usage ratio of the polypropylene, antioxidant 3052, dicumyl peroxide, xylene and acetone is 50-60g:2-4g:0.3g:200mL:300mL.

[0022] A method for preparing a modified polypropylene-based insulating material comprises the following steps:

[0023] Antioxidant polypropylene, heat stabilizer, modified insulation stabilizer and beta nucleating agent are added into a mixer and mixed evenly, then placed into an extruder for melt extrusion, and then cooled, pelletized and dried to obtain a modified polypropylene-based insulation material.

[0024] Beneficial effects of the present invention:

[0025] The modified insulating stabilizer of the present invention contains carboxyl groups on its surface. When blended with antioxidant polypropylene, the carboxyl groups can be bound to the antioxidant polypropylene molecules through non-covalent bonds to form a macromolecular cross-linked network structure on its surface, effectively avoiding the migration of the modified insulating stabilizer from the polypropylene-based insulating material, and improving the compatibility of the modified insulating stabilizer with the antioxidant polypropylene. At the same time, the molecular structure of the modified insulating stabilizer also contains an olefin elastomer modified with acetophenone. On the one hand, the elastomer structure can improve the strength and toughness of the polypropylene-based material through the "silver streak-shear band" effect, improve the phenomenon of the polypropylene material being brittle at low temperatures, and give the polypropylene-based material good mechanical properties. On the other hand, On the one hand, acetophenone can absorb high-energy electrons, effectively inhibit the initiation and growth of electrical dendrites in polypropylene-based materials, improve the conductivity activation energy and DC breakdown strength of polypropylene-based materials, and enhance the electrical resistance of polypropylene-based insulating materials; at the same time, the anhydride groups and carbonyl groups in the molecular structure of the modified insulating stabilizer can introduce more traps with deeper energy levels in polypropylene-based insulating materials, increase the charge trap density, and form an electrostatic shielding layer around the traps, thereby improving the efficiency of capturing carriers, reducing the concentration of carriers in the matrix, effectively avoiding the accumulation of space charges generated under a DC electric field, improving the resistivity, and further enhancing the insulating properties of polypropylene-based materials.

[0026] The present invention effectively improves the insulation aging phenomenon of the insulation layer and improves the DC dielectric properties of the polypropylene-based insulation material by introducing an oxidation-resistant polypropylene with good heat-resistant aging performance. In addition, by introducing a modified insulation stabilizer with good compatibility, the polypropylene-based material is given good strength and insulation, and the insulation layer breakdown phenomenon is effectively avoided. Through the synergistic effect of the two, the service life of the polypropylene-based insulation material is improved. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Example 1

[0029] This embodiment provides a modified elastomer, which is prepared by the following steps:

[0030] A1. Add 10 g of hydrogenated styrene-butadiene block copolymer and 0.5 mL of dioctyl phthalate to 9 g of maleic anhydride, perform melt reaction at 230° C. for 1.5 h, and then cool and dry to obtain an intermediate;

[0031] A2. Add 10 g of the intermediate to 300 mL of dichloromethane, stir and dissolve at 75 °C, cool to room temperature, add 6 mL of acetyl chloride, mix well, then add 0.6 g of anhydrous aluminum chloride, stir and react for 2 h, then place in 500 mL of methanol for precipitation, filter and dry, then dissolve in 300 mL of 50 °C dichloromethane, then place in 500 mL of methanol for precipitation, repeat the operation 3 times, filter and dry to obtain a modified elastomer.

[0032] Example 2

[0033] This embodiment provides a modified elastomer, which is prepared by the following steps:

[0034] A1. Add 10.5 g of hydrogenated styrene-butadiene block copolymer and 0.5 mL of dioctyl phthalate to 10 g of maleic anhydride, perform melt reaction at 235° C. for 2 h, and then cool and dry to obtain an intermediate;

[0035] A2. Add 11 g of the intermediate to 300 mL of dichloromethane, stir and dissolve at 75 °C, cool to room temperature, add 6.5 mL of acetyl chloride, mix well, add 0.8 g of anhydrous aluminum chloride, stir and react for 3 h, place in 500 mL of methanol for precipitation, filter and dry, dissolve in 300 mL of 50 °C dichloromethane, and then place in 500 mL of methanol for precipitation. Repeat the operation 3 times, filter and dry to obtain a modified elastomer.

[0036] Example 3

[0037] This embodiment provides a modified elastomer, which is prepared by the following steps:

[0038] A1. Add 11 g of hydrogenated styrene-butadiene block copolymer and 0.5 mL of dioctyl phthalate to 12 g of maleic anhydride, perform melt reaction at 240° C. for 3 h, and then cool and dry to obtain an intermediate;

[0039] A2. Add 12 g of the intermediate to 300 mL of dichloromethane, stir and dissolve at 75 °C, cool to room temperature, add 7 mL of acetyl chloride, mix well, then add 1 g of anhydrous aluminum chloride, stir and react for 3.5 h, then place in 500 mL of methanol for precipitation, filter and dry, then dissolve in 300 mL of 50 °C dichloromethane, then place in 500 mL of methanol for precipitation, repeat the operation 3 times, filter and dry to obtain a modified elastomer.

[0040] Example 4

[0041] This embodiment provides a modified insulating stabilizer, which is prepared by the following steps:

[0042] 8 g of the modified elastomer obtained in Example 1 and 19 g of 2,4-dihydroxybenzophenone were added to 200 mL of tetrahydrofuran, mixed evenly, 1.8 mL of concentrated sulfuric acid was added, and the mixture was reacted at 65 ° C for 9 h. After cooling, the mixture was placed in 400 mL of deionized water and allowed to stand for 15 min. The precipitate was retained by centrifugation and dried to obtain a modified insulating stabilizer.

[0043] Example 5

[0044] This embodiment provides a modified insulating stabilizer, which is prepared by the following steps:

[0045] To 200 mL of tetrahydrofuran, 10 g of the modified elastomer obtained in Example 2 and 21 g of 2,4-dihydroxybenzophenone were added, the mixture was evenly mixed, 1.8 mL of concentrated sulfuric acid was added, the mixture was reacted at 68 ° C for 9.5 h, and after cooling, it was placed in 400 mL of deionized water and allowed to stand for 15 min. The precipitate was retained by centrifugation and dried to obtain a modified insulating stabilizer.

[0046] Example 6

[0047] This embodiment provides a modified insulating stabilizer, which is prepared by the following steps:

[0048] 13 g of the modified elastomer obtained in Example 3 and 23 g of 2,4-dihydroxybenzophenone were added to 200 mL of tetrahydrofuran, mixed evenly, 1.8 mL of concentrated sulfuric acid was added, reacted at 70 ° C for 10 h, cooled, placed in 400 mL of deionized water for 15 min, and then centrifuged to retain the precipitate and dried to obtain a modified insulating stabilizer.

[0049] Comparative Example 1

[0050] Compared with Example 6, the difference is that the modified elastomer prepared in Example 3 is replaced by an equal amount of hydrogenated styrene-butadiene block copolymer, and the other raw materials and steps are the same.

[0051] Example 7

[0052] This embodiment provides a method for preparing a modified polypropylene-based insulating material, comprising the following steps:

[0053] S1. Synthesis of Antioxidant Polypropylene:

[0054] Add 2 g of antioxidant 3052 (Chinese name: 2-acrylic acid-2-(1,1-dimethylethyl)-6-[[3-(1,1-dimethylethyl)-2-hydroxy-5-methylphenyl]methyl]-4-tolyl ester) and 0.3 g of diisopropylbenzene peroxide to 50 g of polypropylene, melt react at 180°C for 1 hour, cool and dry, place in 200 mL of xylene, dissolve and reflux at 138°C, cool, place in 300 mL of acetone, and let stand to precipitate, then filter and dry to obtain antioxidant polypropylene;

[0055] S2. Preparation of modified polypropylene-based insulating materials:

[0056] 90 parts by weight of antioxidant polypropylene, 4 parts by weight of heat stabilizer, 18 parts by weight of modified insulating stabilizer prepared in Example 4, and 1 part by weight of β-nucleating agent were added into a mixer and mixed evenly, then placed into an extruder for melt extrusion, and then cooled, pelletized, and dried to obtain a modified polypropylene-based insulating material.

[0057] Example 8

[0058] This embodiment provides a method for preparing a modified polypropylene-based insulating material, comprising the following steps:

[0059] S1. Synthesis of Antioxidant Polypropylene:

[0060] Add 3g of antioxidant 3052 and 0.3g of diisopropylbenzene peroxide to 55g of polypropylene, melt react at 185°C for 1.5h, cool and dry, place in 200mL of xylene, dissolve and reflux at 138°C, cool, place in 300mL of acetone, let stand and precipitate, filter and dry to obtain antioxidant polypropylene;

[0061] S2. Preparation of modified polypropylene-based insulating materials:

[0062] 100 parts by weight of antioxidant polypropylene, 5 parts by weight of heat stabilizer, 20 parts by weight of modified insulating stabilizer prepared in Example 5, and 2 parts by weight of β-nucleating agent were added into a mixer and mixed evenly, then placed into an extruder for melt extrusion, and then cooled, pelletized, and dried to obtain a modified polypropylene-based insulating material.

[0063] Example 9

[0064] This embodiment provides a method for preparing a modified polypropylene-based insulating material, comprising the following steps:

[0065] S1. Synthesis of Antioxidant Polypropylene:

[0066] Add 4g of antioxidant 3052 and 0.3g of diisopropylbenzene peroxide to 60g of polypropylene, melt react at 190°C for 2h, cool and dry, place in 200mL of xylene, dissolve and reflux at 138°C, cool, place in 300mL of acetone and let stand for precipitation, then filter and dry to obtain antioxidant polypropylene;

[0067] S2. Preparation of modified polypropylene-based insulating materials:

[0068] 110 parts by weight of antioxidant polypropylene, 6 parts by weight of heat stabilizer, 24 parts by weight of modified insulating stabilizer prepared in Example 6, and 3 parts by weight of β-nucleating agent were added into a mixer and mixed evenly, then placed into an extruder for melt extrusion, and then cooled, pelletized, and dried to obtain a modified polypropylene-based insulating material.

[0069] Comparative Example 2

[0070] Compared with Example 7, the difference is that the modified insulating stabilizer prepared in Comparative Example 1 is used, and the other raw materials and steps are the same.

[0071] Comparative Example 3

[0072] Compared with Example 7, the difference is that the modified insulating stabilizer is replaced by an equal amount of a commercially available voltage stabilizer, and the other raw materials and steps are the same.

[0073] Comparative Example 4

[0074] Compared with Example 7, the difference is that the antioxidant polypropylene is replaced by polypropylene in an equal amount, and the other raw materials and steps are the same.

[0075] Performance tests were performed on Examples 7 to 9 and Comparative Examples 2 to 4. The breakdown field strength was as follows: GB / T 1408.1-2016. The aging performance was as follows: GB / T 2951.12-2008. The aging temperature was set to 135° C. The aging time was 7 days. The volume resistivity before and after aging was tested. The volume resistivity was as follows: GB / T 31838.2-2019. The tensile strength was as follows: GB / T 1040.2-2006. The elongation at break was as follows: GB / T 1040.1-2018. The results are shown in Table 1.

[0076] Table 1

[0077]

[0078] As can be seen from Table 1, the breakdown field strength and volume resistivity of the polypropylene-based insulating materials prepared from the antioxidant polypropylene and the modified insulating stabilizer in Examples 7-9 are higher than those in Comparative Examples 2-4, and the materials have good electrical resistance, and the tensile strength can reach up to 38.9 N / mm 2, and the elongation at break can reach up to 619%, with good strength and toughness; in addition, compared with Comparative Examples 2 and 4, the volume resistivity of Example 7 before and after aging is higher than that of Comparative Examples 2 and 4, indicating that the polypropylene-based insulating material prepared by the synergistic combination of antioxidant polypropylene and modified insulating stabilizer has better insulation aging resistance.

[0079] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0080] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A modified polypropylene-based insulating material, characterized in that: It includes the following raw materials in parts by weight: 90-110 parts of antioxidant polypropylene, 4-6 parts of heat stabilizer, 18-24 parts of modified insulation stabilizer, 1-3 parts of β nucleating agent; the antioxidant polypropylene is antioxidant 3052 grafted polypropylene; The modified insulating stabilizer is obtained by the following steps: Add the modified elastomer and 2,4-dihydroxybenzophenone to tetrahydrofuran, mix well, add concentrated sulfuric acid, react at 65-70°C for 9-10 hours, cool, place in deionized water for 15 minutes, centrifuge to retain the precipitate, and dry to obtain a modified insulating stabilizer.

2. A modified polypropylene-based insulating material according to claim 1, characterized in that: The usage ratio of tetrahydrofuran, modified elastomer, 2,4-dihydroxybenzophenone, concentrated sulfuric acid and deionized water is 200 mL: 8-13 g: 19-23 g: 1.8 mL: 400 mL.

3. The modified polypropylene-based insulating material according to claim 1, characterized in that: The modified elastomer is prepared by the following steps: A1. Add hydrogenated styrene-butadiene block copolymer and dioctyl phthalate to maleic anhydride, perform melt reaction at 230-240° C. for 1.5-3 h, and then cool and dry to obtain an intermediate; A2. Add the intermediate to dichloromethane, stir and dissolve at 75°C, cool to room temperature, add acetyl chloride, mix well, add anhydrous aluminum chloride, stir and react for 2-3.5 hours, and then purify, filter and dry to obtain the modified elastomer.

4. A modified polypropylene-based insulating material according to claim 3, characterized in that: The dosage ratio of the maleic anhydride, hydrogenated styrene-butadiene block copolymer and dioctyl phthalate is 9-12 g: 10-11 g: 0.5 mL.

5. The modified polypropylene-based insulating material according to claim 3, characterized in that: The usage ratio of the dichloromethane, the intermediate, acetyl chloride and anhydrous aluminum chloride is 300 mL: 10-12 g: 6-7 mL: 0.6-1 g.

6. The modified polypropylene-based insulating material according to claim 3, characterized in that: The purification treatment comprises placing the product in excess methanol for precipitation, filtering, drying, then dissolving the product in 50° C. dichloromethane, and then placing the product in excess methanol for precipitation, and repeating the operation for multiple times.

7. The modified polypropylene-based insulating material according to claim 1, characterized in that: The antioxidant polypropylene is prepared by the following steps: Add antioxidant 3052 and diisopropylbenzene peroxide to polypropylene, melt react at 180-190°C for 1-2h, cool and dry, place in xylene, dissolve and reflux at 138°C, cool, place in acetone for precipitation, filter and dry to obtain antioxidant polypropylene.

8. A modified polypropylene-based insulating material according to claim 7, characterized in that: The usage ratio of the polypropylene, the antioxidant 3052, the diisopropylbenzene peroxide, the xylene and the acetone is 50-60 g: 2-4 g: 0.3 g: 200 mL: 300 mL.

9. The method for preparing a modified polypropylene-based insulating material according to claim 1, characterized in that: The following steps are involved: Antioxidant polypropylene, heat stabilizer, modified insulation stabilizer and beta nucleating agent are added into a mixer and mixed evenly, then placed into an extruder for melt extrusion, and then cooled, pelletized and dried to obtain a modified polypropylene-based insulation material.

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