Corrosion and stress cracking resistant material and its use

Abstract

The application discloses a kind of corrosion-resistant, stress cracking-resistant material and its application, it is related to modified plastics technical field.The application uses high-density polyethylene and polypropylene as matrix, by adding elastomer, modified filler, lubricant and antioxidant, by mixing, extruding granulation, prepared composite material has excellent corrosion resistance and stress cracking resistance performance.Elastomer can disperse external stress, inhibit the propagation of silver line, improve the stress cracking resistance of composite material;Modified filler can adsorb or block solvent, to inhibit the diffusion of solvent in material, avoid the continuous penetration of solvent on the force between high and low density polyethylene and polypropylene molecular chain, thereby inhibit the propagation of silver line, improve the stress cracking resistance of material.In addition, the application uses tannic acid and sodium metaaluminate combination to modify mica and prepare modified filler, has synergistic effect on improving the stress cracking resistance of composite material.

Description

Technical Field

[0001] This invention relates to the field of modified plastics technology, and in particular to a corrosion-resistant and stress-cracking-resistant material and its applications. Background Technology

[0002] High-density polyethylene (HDPE), a highly crystalline thermoplastic polymer, possesses excellent corrosion resistance, ease of processing, dielectric properties, and moisture permeability, making it widely used in food packaging, fluid transportation, electronics, and automotive manufacturing. While HDPE's simple linear molecular chain structure endows it with high density, high strength, and high modulus, it also results in poor toughness, resistance to environmental stress cracking, and processability. It is particularly prone to environmental stress cracking during application, thus shortening its service life and limiting its application range.

[0003] Currently, molecular design techniques such as blending modification, macromonomer copolymerization, and the introduction of long-chain branches are employed to optimize the environmental stress cracking performance of high-density polyethylene (HDPE). Among these methods, blending modification has become the preferred optimization technique for stress cracking resistance in industry due to its advantages of low cost, simple preparation method, and low equipment requirements.

[0004] In existing technology, the paper "Research on Toughening Modification of High-Density Polyethylene" (Li Dongdong, Jilin University of Architecture, June 2024) discloses the addition of highly elastic polyolefin elastomers—ethylene-octene copolymer (POE) and propylene-ethylene random copolymer (PEC)—to high-density polyethylene. By uniformly distributing the elastomers in the HDPE matrix, the stress acting on the brittle HDPE matrix is ​​reduced, thereby improving the environmental stress cracking resistance of HDPE. Environmental stress cracking (ESC) refers to the phenomenon where materials, after prolonged contact with solvents during use, crack from the surface of the product under combined stress, eventually leading to failure. Solvents disrupt the molecular bonds of the material, creating large gaps that gradually expand into crevices, eventually resulting in tip cracks. In the aforementioned paper, the addition of elastomers to high-density polyethylene does not possess the ability to adsorb or block solvents. Solvents can still diffuse freely through the material. Even if stress concentration is alleviated by the elastomers, the continuous penetration of solvents disrupts the intermolecular forces of HDPE, leading to accelerated crevice expansion and thus environmental stress cracking.

[0005] Therefore, it is necessary to use high-density polyethylene as the matrix and modify it by blending to obtain a corrosion-resistant material, so as to reduce the damage between high-density polyethylene molecules by solvents during the use of the material, thereby improving the material's stress cracking resistance. Summary of the Invention

[0006] To address the aforementioned limitations of existing technologies, the present invention aims to provide a corrosion-resistant and stress-cracking-resistant material and its applications. This invention uses high-density polyethylene and polypropylene as the matrix, and by adding elastomers, modified fillers, lubricants, and antioxidants, the mixture is compounded and then extruded and granulated to obtain a composite material with excellent corrosion resistance and stress-cracking resistance. Specifically, the elastomer disperses external stress, inhibits craze propagation, and improves the stress-cracking resistance of the composite material; the modified filler adsorbs or blocks solvents to inhibit solvent diffusion within the material, preventing continuous solvent penetration from affecting the forces between the high-density polyethylene and polypropylene molecular chains, thereby inhibiting craze propagation and improving the material's stress-cracking resistance. Furthermore, this invention uses a combination of ellagic acid and sodium aluminate to modify mica, resulting in a modified filler that has a synergistic effect in improving the stress-cracking resistance of the composite material.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a corrosion-resistant and stress-cracking-resistant material, comprising the following raw materials in parts by weight:

[0009] 45-55 parts high-density polyethylene, 15-25 parts polypropylene, 10-15 parts elastomer, 5-10 parts modified filler, 1-1.5 parts lubricant, and 1-2 parts antioxidant;

[0010] The modified filler is prepared by the following method:

[0011] (1) Disperse mica flakes in deionized water to obtain mica flake dispersion; add tris(hydroxymethyl)aminomethane to the mica flake dispersion and mix evenly, then add ellagic acid to react. After the reaction is completed, filter, wash and dry to obtain ellagic acid modified mica flakes.

[0012] (2) Disperse ellagic acid modified mica flakes in water to obtain ellagic acid modified mica solution; add urea to ellagic acid modified mica solution and stir, then add sodium aluminate solution to react. After the reaction is completed, cool and dry to obtain modified filler.

[0013] Preferably, in step (1), the mica sheet is a sericite sheet.

[0014] Preferably, in step (1), the ratio of mica flakes to water is 1 mg: (1.5-2.5) mL.

[0015] Preferably, in step (1), the mass ratio of mica flakes, tris(hydroxymethyl)aminomethane, and ellagic acid is 0.1:(0.2-0.3):(0.3-0.5).

[0016] Preferably, in step (1), the reaction temperature is 50-80℃ and the reaction time is 5-7h.

[0017] Preferably, in step (2), the ratio of ellagic acid-modified mica flakes to water is 1 mg: (3-5) mL.

[0018] Preferably, in step (2), the mass ratio of sodium aluminate in ellagic acid-modified mica, urea, and sodium aluminate solution is 1 mg: (5-8) mg: (0.5-0.6) g.

[0019] Preferably, in step (2), the sodium aluminate solution is prepared by mixing sodium aluminate and water at a ratio of (0.5-0.6) g: 5 mL.

[0020] Preferably, in step (2), the mixture is stirred for 25-35 minutes.

[0021] Preferably, in step (2), the reaction temperature is 150-200℃ and the reaction time is 2.5-3.5h.

[0022] Preferably, in step (2), the drying temperature is 70-90℃ and the drying time is 12h.

[0023] Preferably, the elastomer is polyethylene-octene co-elastomer (POE) and / or polyethylene-vinyl acetate elastomer (EVA).

[0024] Preferably, the antioxidant is antioxidant 1010 or antioxidant 168.

[0025] Preferably, the lubricant is stearate and / or polyethylene wax.

[0026] A second aspect of the present invention provides a method for preparing the above-mentioned corrosion-resistant and stress-cracking-resistant material, comprising the following steps:

[0027] After the raw materials are mixed and dried, they are then kneaded, cooled, and granulated to obtain a corrosion-resistant and stress-cracking-resistant material.

[0028] Preferably, the drying is vacuum drying, and the drying temperature is 60-80℃.

[0029] Preferably, the mixing temperature is 160-200℃ and the mixing time is 10-15min.

[0030] A third aspect of the present invention provides the application of the above-mentioned corrosion-resistant and stress-cracking-resistant materials in the manufacture of fuel tanks.

[0031] The beneficial effects of this invention are:

[0032] This invention uses high-density polyethylene (HDPE) and polypropylene (PP) as the matrix. By adding elastomers and modified fillers, the mixture is compounded and then extruded and granulated to obtain a composite material with excellent corrosion resistance and stress cracking resistance. The use of HDPE and PP as the matrix materials leverages their excellent corrosion resistance to improve the final composite material's corrosion resistance. The addition of elastomers and modified fillers enhances the material's stress cracking resistance. The island-island structure of the elastomers disperses external stress, inhibits craze propagation, and improves the composite material's stress cracking resistance. The modified fillers adsorb or block solvents, inhibiting solvent diffusion within the composite material and preventing continuous solvent penetration from affecting the forces between the HDPE and PP molecular chains, thereby inhibiting craze propagation and improving the material's stress cracking resistance. Furthermore, this invention uses a combination of ellagic acid and sodium aluminate to modify mica, resulting in a modified filler that has a synergistic effect in improving the composite material's stress cracking resistance. Detailed Implementation

[0033] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, 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 application pertains.

[0034] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0035] The experimental materials used in the embodiments of this invention are all conventional experimental materials in the art and can be purchased through commercial channels.

[0036] Example 1: Corrosion-resistant and stress-cracking-resistant materials

[0037] 1. Composition:

[0038] The corrosion-resistant and stress-cracking-resistant material is prepared by mixing high-density polyethylene, polypropylene, elastomer, modified filler, lubricant and antioxidant in a mass ratio of 50:20:12:8:1.2:1.5.

[0039] The elastomer is a polyethylene-octene co-elastomer (POE), the lubricant is sodium stearate, and the antioxidant is antioxidant 1010.

[0040] The modified filler is prepared by the following method:

[0041] (1) After mixing sericite flakes and deionized water at a material-to-liquid ratio of 1 mg: 2 mL, a mica flake dispersion was obtained. Tris(hydroxymethyl)aminomethane was added to the mica flake dispersion and mixed evenly. Then ellagic acid was added and reacted at 65 °C for 6 h. The mass ratio of mica flakes, tris(hydroxymethyl)aminomethane and ellagic acid was 0.1:0.25:0.4. After the reaction was completed, the mixture was filtered, washed and dried to obtain ellagic acid-modified mica flakes.

[0042] (2) Sodium aluminate and deionized water were mixed at a ratio of 0.57 g: 5 mL to obtain a sodium aluminate solution; ellagic acid modified mica flakes and deionized water were mixed at a ratio of 1 mg: 100 mL to obtain an ellagic acid modified mica solution; urea was added to the ellagic acid modified mica solution and stirred for 30 min to mix it evenly, and then sodium aluminate solution was added. The mass ratio of ellagic acid modified mica, urea and sodium aluminate was 1 mg: 6 mg: 0.57 g. The mixture was reacted at 180 °C for 3 h. After the reaction was completed, the mixture was cooled to room temperature and dried at 80 °C for 12 h to obtain the modified filler.

[0043] 2. Preparation method:

[0044] After the raw materials are mixed evenly, they are vacuum dried at 70°C, and then mixed in an internal mixer at 180°C for 12 minutes. After the mixing is completed, the mixture is cooled to room temperature and granulated to obtain a corrosion-resistant and stress-cracking-resistant material.

[0045] Example 2: Corrosion-resistant and stress-cracking-resistant materials

[0046] 1. Composition:

[0047] The corrosion-resistant and stress-cracking-resistant material is prepared by mixing high-density polyethylene, polypropylene, elastomer, modified filler, lubricant and antioxidant in a mass ratio of 45:15:10:5:1:1.

[0048] The elastomer is a polyethylene-octene co-elastomer (POE), the lubricant is sodium stearate, and the antioxidant is antioxidant 1010.

[0049] The modified filler is prepared by the following method:

[0050] (1) Mica flakes and deionized water were mixed at a material-to-liquid ratio of 1 mg: 1.5 mL to obtain a mica flake dispersion. Tris(hydroxymethyl)aminomethane was added to the mica flake dispersion and mixed evenly. Then ellagic acid was added and reacted at 50 °C for 7 h. The mass ratio of mica flakes, tris(hydroxymethyl)aminomethane and ellagic acid was 0.1:0.2:0.3. After the reaction was completed, the mixture was filtered, washed and dried to obtain ellagic acid modified mica flakes.

[0051] (2) Sodium aluminate and deionized water were mixed at a ratio of 0.5g:5mL to obtain a sodium aluminate solution; ellagic acid modified mica flakes and deionized water were mixed at a ratio of 1mg:80mL to obtain an ellagic acid modified mica solution; urea was added to the ellagic acid modified mica solution and stirred for 25min to mix it evenly, and then sodium aluminate solution was added. The mass ratio of ellagic acid modified mica, urea and sodium aluminate was 1mg:5mg:0.5g. The reaction was carried out at 150℃ for 3.5h. After the reaction was completed, the mixture was cooled to room temperature and dried at 70℃ for 12h to obtain the modified filler.

[0052] 2. Preparation method:

[0053] After the raw materials are mixed evenly, they are vacuum dried at 60°C, and then mixed in an internal mixer at 160°C for 15 minutes. After the mixing is completed, the mixture is cooled to room temperature and granulated to obtain a corrosion-resistant and stress-cracking-resistant material.

[0054] Example 3: Corrosion-resistant and stress-cracking-resistant materials

[0055] 1. Composition:

[0056] The corrosion-resistant and stress-cracking-resistant material is prepared by mixing high-density polyethylene, polypropylene, elastomer, modified filler, lubricant and antioxidant in a mass ratio of 55:25:15:10:1.5:2.

[0057] The elastomer is a polyethylene-octene co-elastomer (POE), the lubricant is sodium stearate, and the antioxidant is antioxidant 1010.

[0058] The modified filler is prepared by the following method:

[0059] (1) Mica flakes and deionized water were mixed at a material-to-liquid ratio of 1 mg: 2.5 mL to obtain a mica flake dispersion. Tris(hydroxymethyl)aminomethane was added to the mica flake dispersion and mixed evenly. Then ellagic acid was added and reacted at 80 °C for 5 h. The mass ratio of mica flakes, tris(hydroxymethyl)aminomethane and ellagic acid was 0.1:0.3:0.5. After the reaction was completed, the mixture was filtered, washed and dried to obtain ellagic acid modified mica flakes.

[0060] (2) Sodium aluminate and deionized water were mixed at a ratio of 0.6g:5mL to obtain a sodium aluminate solution; ellagic acid modified mica flakes and deionized water were mixed at a ratio of 1mg:120mL to obtain an ellagic acid modified mica solution; urea was added to the ellagic acid modified mica solution and stirred for 35min to mix it evenly, and then sodium aluminate solution was added. The mass ratio of ellagic acid modified mica, urea and sodium aluminate was 1mg:8mg:0.6g. The reaction was carried out at 150℃ for 3.5h. After the reaction was completed, the mixture was cooled to room temperature and dried at 90℃ for 12h to obtain the modified filler.

[0061] 2. Preparation method:

[0062] After the raw materials are mixed evenly, they are vacuum dried at 80°C, and then mixed in an internal mixer at 200°C for 10 minutes. After the mixing is completed, the mixture is cooled to room temperature and granulated to obtain a corrosion-resistant and stress-cracking-resistant material.

[0063] Comparative Example 1:

[0064] The difference between this comparative example and Example 1 is that unmodified mica sheets were used as fillers to prepare the composite material.

[0065] Comparative Example 2:

[0066] The difference between this comparative example and Example 1 is that the modified filler is ellagic acid-modified mica flakes, which are prepared by the following method:

[0067] Mica flakes and deionized water were mixed at a ratio of 1 mg: 2 mL to obtain a mica flake dispersion. Tris(hydroxymethyl)aminomethane was added to the mica flake dispersion and mixed evenly. Then ellagic acid was added, and the mixture was reacted at 65 °C for 6 h. The mass ratio of mica flakes, tris(hydroxymethyl)aminomethane and ellagic acid was 0.1:0.25:0.4. After the reaction was completed, the mixture was filtered, washed and dried to obtain ellagic acid-modified mica flakes.

[0068] Comparative Example 3:

[0069] The difference between this comparative example and Example 1 is that the modified filler is sodium aluminate modified mica sheet, which is prepared by the following method:

[0070] Mica flakes and deionized water were mixed at a ratio of 1 mg: 2 mL to obtain a mica flake dispersion. Sodium aluminate and deionized water were mixed at a ratio of 0.57 g: 5 mL to obtain a sodium aluminate solution. Urea was added to the mica flake dispersion, followed by the sodium aluminate solution. The mass ratio of mica, urea, and sodium aluminate was 1 mg: 6 mg: 0.57 g. The mixture was reacted at 180 °C for 3 h. After the reaction was completed, the mixture was cooled to room temperature and dried at 80 °C for 12 h to obtain the modified filler.

[0071] Experimental example:

[0072] 1. Resistance to stress cracking:

[0073] Following the test procedures in GB / T1842-2008 Environmental Stress Cracking Test Method for Polyethylene Plastics, the environmental stress cracking time F of each group of samples was measured at 50℃ in an aqueous solution containing 10% (v / v) nonylphenol polyoxyethylene ether (TX-10). 50 The results are shown in Table 1.

[0074] 2. Corrosion resistance:

[0075] (1) Resistant to acid corrosion

[0076] Equal amounts of the composite materials prepared in Example 1 and Comparative Examples 1-4 were taken and immersed in 98wt% concentrated sulfuric acid for 30 min. The tensile strength of the composite material samples before and after immersion was tested and the loss rate was calculated. The results are shown in Table 1.

[0077] (2) Alkali corrosion resistant

[0078] Equal amounts of the composite materials prepared in Example 1 and Comparative Examples 1-4 were taken and immersed in a 10% sodium hydroxide solution for 30 minutes. The tensile strength of the composite material samples before and after immersion was tested and the loss rate was calculated. The results are shown in Table 1.

[0079] The formula for calculating the loss rate is:

[0080] Loss rate = [(tensile strength of composite material before immersion - tensile strength of composite material after immersion) / tensile strength of composite material before immersion] × 100%.

[0081] Table 1 Corrosion resistance and environmental stress cracking resistance of materials in each group.

[0082]

[0083]

[0084] As shown in Table 1, the material prepared by using polypropylene and high-density polyethylene as the matrix and adding elastomers and modified fillers exhibits good corrosion resistance and stress cracking resistance. Specifically, the material prepared using only mica as filler shows a high environmental stress cracking time Fo. 50 The environmental stress cracking time F of the material prepared by using ellagic acid-modified mica as a modified filler is 325h. 50 The environmental stress cracking time F of the material prepared by using sodium aluminate-modified mica as a modified filler was 398h. 50 The time is 376h, while the present invention uses a combination of ellagic acid and sodium aluminate to modify mica, which has a synergistic effect in improving the stress cracking resistance of the material.

[0085] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A corrosion-resistant and stress-cracking-resistant material, characterized in that, The ingredients include the following parts by weight: 45-55 parts high-density polyethylene, 15-25 parts polypropylene, 10-15 parts elastomer, 5-10 parts modified filler, 1-1.5 parts lubricant, and 1-2 parts antioxidant; The modified filler is prepared by the following method: (1) Disperse mica flakes in deionized water to obtain mica flake dispersion; add tris(hydroxymethyl)aminomethane to the mica flake dispersion and mix evenly, then add ellagic acid to react. After the reaction is complete, filter, wash and dry to obtain ellagic acid modified mica flakes. The material-to-liquid ratio of mica flakes to water is 1 mg: (1.5-2.5) mL; the mass ratio of mica flakes, tris(hydroxymethyl)aminomethane, and ellagic acid is 0.1: (0.2-0.3): (0.3-0.5); the reaction temperature is 50-80℃, and the reaction time is 5-7 h. (2) Disperse ellagic acid modified mica flakes in water to obtain ellagic acid modified mica solution; add urea to ellagic acid modified mica solution, then add sodium aluminate solution to react. After the reaction is completed, cool and dry to obtain modified filler. The ratio of ellagic acid-modified mica to water is 1 mg:(3-5) mL; the sodium aluminate solution is prepared by mixing sodium aluminate and water at a ratio of (0.5-0.6) g:5 mL; the mass ratio of sodium aluminate in ellagic acid-modified mica, urea, and sodium aluminate solution is 1 mg:(5-8) mg:(0.5-0.6) g; the reaction temperature is 150-200℃, and the reaction time is 2.5-3.5 h. The preparation method of the corrosion-resistant and stress-cracking-resistant material is as follows: After the raw materials are mixed and dried, they are then kneaded, cooled, and granulated to obtain a corrosion-resistant and stress-cracking-resistant material. The drying is done under vacuum at a temperature of 60-80℃, and the kneading temperature is 160-200℃ for 10-15 minutes.

2. The corrosion-resistant and stress-cracking-resistant material as described in claim 1, characterized in that, The elastomer is a polyethylene-octene elastomer or a polyethylene-vinyl acetate elastomer; the antioxidant is antioxidant 1010 or antioxidant 168; and the lubricant is stearate and / or polyethylene wax.

3. The application of the corrosion-resistant and stress-cracking-resistant material as described in claim 1 or 2 in the manufacture of fuel tanks.

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