Corrosion-resistant and stress cracking-resistant material and application thereof

Abstract

The invention discloses a corrosion-resistant and stress cracking-resistant material and application thereof, and relates to the technical field of modified plastics. According to the invention, the high-density polyethylene and the polypropylene are adopted as matrixes, the elastomer, the modified filler, the lubricant and the antioxidant are added, and mixing and extrusion granulation are carried out, so that the prepared composite material has excellent corrosion resistance and stress cracking resistance. Wherein the elastomer can disperse external stress, inhibit crazing expansion and improve the stress cracking resistance of the composite material; the modified filler can adsorb or block the solvent to inhibit diffusion of the solvent in the material and avoid acting force of continuous permeation of the solvent on molecular chains of high-density and low-density polyethylene and polypropylene, so that craze expansion is inhibited, and the stress cracking resistance of the material is improved. In addition, the composition of ellagic acid and sodium metaaluminate is adopted to modify mica to prepare the modified filler, and the modified filler has a synergistic effect on improving the stress cracking resistance of the composite material.

Description

Technical Field

[0001] The invention relates to the technical field of modified plastics, in particular to a corrosion-resistant and stress-cracking-resistant material and application thereof. Background Art

[0002] High-density polyethylene (HDPE), as a highly crystalline thermoplastic polymer, has good corrosion resistance, easy processing, dielectric properties and moisture permeability, and is widely used in food packaging, fluid transportation, electronic appliances, automobile manufacturing and other fields. Although the simple linear molecular chain structure of HDPE gives it high density, high strength and high modulus, it also determines that HDPE has poor toughness, environmental stress cracking resistance and processability. It is particularly prone to environmental stress cracking during the application process, which shortens the use time of HDPE and limits the application scope of HDPE.

[0003] At present, molecular design is carried out by means of blending modification, macromonomer copolymerization, and introduction of long chain branches to optimize the environmental stress cracking performance of high-density polyethylene. Among them, compared with other means, blending modification has become the preferred means of optimizing stress cracking resistance in the industry due to its advantages such as low cost, simple preparation method and low equipment requirements.

[0004] In the prior art, the paper "Research on Toughening Modification of High-density Polyethylene" (Li Dongdong, Jilin Jianzhu University, 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 evenly distributing the elastomer in the HDPE matrix to reduce the stress acting on the brittle matrix HDPE, the environmental stress cracking resistance of HDPE is improved. Environmental stress cracking (ESC) refers to the phenomenon that the material is in contact with the solvent for a long time during use, and under the action of combined stress, cracking begins from the surface of the product and then suffers damage. Among them, the solvent will destroy the molecular bonds of the material, causing the material to form a large gap, gradually expand into silver streaks, and finally appear tip cracks. In the above paper, an elastomer is added to high-density polyethylene. Since the added elastomer itself does not have the ability to absorb or block the solvent, the solvent can still diffuse freely through the material. Even if the stress concentration is relieved by the elastomer, the continuous penetration of the solvent will destroy the force between the HDPE molecular chains, resulting in the accelerated expansion of the silver streaks, resulting in environmental stress cracking.

[0005] Therefore, it is necessary to use high-density polyethylene as a matrix and perform blending modification on it to obtain a corrosion-resistant material in order to reduce the damage of the solvent to the molecules of high-density polyethylene during the use of the material, thereby improving the material's resistance to stress cracking. Summary of the invention

[0006] In view of the above-mentioned prior art, the object of the present invention is to provide a corrosion-resistant and stress-crack-resistant material and its application. The present invention uses high-density polyethylene and polypropylene as the matrix, and by adding an elastomer, a modified filler lubricant and an antioxidant, and extruding and pelletizing after mixing, a composite material with excellent corrosion resistance and stress-crack resistance is obtained. Among them, the elastomer can disperse external stress, inhibit the propagation of crazes, and improve the stress-crack resistance of the composite material; the modified filler can adsorb or block solvents to inhibit the diffusion of solvents in the material, avoid the continuous penetration of solvents into the intermolecular forces between high-density polyethylene and polypropylene molecules, thereby inhibiting the propagation of crazes and improving the stress-crack resistance of the material. In addition, the present invention uses a combination of ellagic acid and sodium metaaluminate to modify mica to obtain a modified filler, which has a synergistic effect in improving the stress-crack resistance of the composite material.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] In the first aspect of the present invention, a corrosion-resistant and stress-crack-resistant material is provided, which comprises the following raw materials in parts by weight:

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

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

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

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

[0013] Preferably, in step (1), the mica flakes are sericite flakes.

[0014] Preferably, in step (1), the material 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 °C and the reaction time is 5-7 h.

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

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

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

[0020] Preferably, in step (2), stir for 25 - 35 min.

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

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

[0023] Preferably, the elastomer is polyethylene-octene coelastomer (POE) and / or ethylene-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] In the second aspect of the present invention, there is provided a method for preparing the above corrosion-resistant and stress-crack-resistant material, comprising the following steps:

[0027] Mix the raw materials and then dry them, followed by mixing, cooling, and pelletizing to obtain the corrosion-resistant and stress-crack-resistant material.

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

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

[0030] In the third aspect of the present invention, there is provided the application of the above corrosion-resistant and stress-crack-resistant material in the preparation of a fuel tank.

[0031] Advantages of the present invention:

[0032] The present invention uses high-density polyethylene and polypropylene as the matrix. By adding an elastomer and a modified filler, and then mixing and extruding to granulate, the obtained composite material has excellent corrosion resistance and stress cracking resistance. Among them, high-density polyethylene and polypropylene are used as the matrix materials. Utilizing their excellent corrosion resistance can improve the corrosion resistance of the finally obtained composite material. By adding an elastomer and a modified filler, the stress cracking resistance of the material is improved. The sea-island structure of the elastomer can disperse external stress, inhibit the propagation of crazes, and improve the stress cracking resistance of the composite material; the modified filler can adsorb or block solvents to inhibit the diffusion of solvents in the composite material, avoid the continuous penetration of solvents into the intermolecular forces between high- and low-density polyethylene and polypropylene molecules, thereby inhibiting the propagation of crazes and improving the stress cracking resistance of the material. In addition, the present invention uses a combination of ellagic acid and sodium metaaluminate to modify mica to obtain a modified filler, which has a synergistic effect in improving the stress cracking resistance of the composite material. Detailed Embodiments

[0033] It should be noted that the following detailed descriptions are all illustrative and are intended to provide further explanations for the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0034] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

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

[0036] Example 1: Material with Corrosion Resistance and Stress Cracking Resistance

[0037] 1. Composition:

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

[0039] Among them, the elastomer is 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) Mix sericite flakes and deionized water at a material-liquid ratio of 1 mg: 2 mL to obtain a sericite flake dispersion; add tris(hydroxymethyl)aminomethane to the sericite flake dispersion and mix evenly, then add ellagic acid, and react at 65 °C for 6 h. Among them, the mass ratio of sericite flakes, tris(hydroxymethyl)aminomethane and ellagic acid is 0.1:0.25:0.4. After the reaction, filter, wash and dry to obtain ellagic acid-modified sericite flakes;

[0042] (2) Mix sodium aluminate and deionized water at a material-liquid ratio of 0.57 g: 5 mL to obtain a sodium aluminate solution; mix ellagic acid-modified sericite flakes and deionized water at a material-liquid ratio of 1 mg: 100 mL to obtain an ellagic acid-modified sericite solution; add urea to the ellagic acid-modified sericite solution and stir for 30 min to mix evenly, then add the sodium aluminate solution. Among them, the mass ratio of ellagic acid-modified sericite, urea and sodium aluminate is 1 mg: 6 mg: 0.57 g. React at 180 °C for 3 h. After the reaction, cool to room temperature and dry at 80 °C for 12 h to obtain a modified filler.

[0043] 2. Preparation method:

[0044] Mix the raw materials evenly and place them in a vacuum dryer at 70 °C, then place them in a mixer and knead at 180 °C for 12 min. After the kneading is completed, cool to room temperature and granulate to obtain a material with corrosion resistance and stress cracking resistance.

[0045] Example 2: Material with corrosion resistance and stress cracking resistance

[0046] 1. Composition:

[0047] The material with corrosion resistance and stress cracking resistance 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] Among them, the elastomer is polyethylene-octene coelastomer (POE), the lubricant is sodium stearate, and the antioxidant is antioxidant 1010;

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

[0050] (1) Mix sericite flakes and deionized water at a material-liquid ratio of 1 mg: 1.5 mL to obtain a sericite flake dispersion; add tris(hydroxymethyl)aminomethane to the sericite flake dispersion and mix evenly, then add ellagic acid, and react at 50 °C for 7 h. Among them, the mass ratio of sericite flakes, tris(hydroxymethyl)aminomethane and ellagic acid is 0.1:0.2:0.3. After the reaction, filter, wash and dry to obtain ellagic acid-modified sericite flakes;

[0051] (2) Mix sodium aluminate and deionized water according to the liquid ratio of 0.5 g: 5 mL to obtain a sodium aluminate solution; mix ellagic acid-modified mica flakes and deionized water according to the liquid ratio of 1 mg: 80 mL to obtain an ellagic acid-modified mica solution; add urea to the ellagic acid-modified mica solution and stir for 25 min to mix evenly, then add the sodium aluminate solution. Among them, the mass ratio of ellagic acid-modified mica, urea and sodium aluminate is 1 mg: 5 mg: 0.5 g. React at 150 °C for 3.5 h. After the reaction is completed, cool to room temperature and dry at 70 °C for 12 h to obtain the modified filler.

[0052] 2. Preparation method:

[0053] Mix the raw materials evenly and place them in a vacuum dryer at 60 °C, then place them in a mixer and knead at 160 °C for 15 min. After the kneading is completed, cool to room temperature and granulate to obtain a corrosion-resistant and stress-crack-resistant material.

[0054] Example 3: Corrosion-resistant and stress-crack-resistant material

[0055] 1. Composition:

[0056] The corrosion-resistant and stress-crack-resistant material is prepared by mixing high-density polyethylene, polypropylene, elastomer, modified filler, lubricant and antioxidant according to the mass ratio of 55:25:15:10:1.5:2;

[0057] Among them, the elastomer is polyethylene-octene copolymer 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) Mix mica flakes and deionized water according to the liquid ratio of 1 mg: 2.5 mL to obtain a mica flake dispersion; add tris(hydroxymethyl)aminomethane to the mica flake dispersion and mix evenly, then add ellagic acid, and react at 80 °C for 5 h. Among them, the mass ratio of mica flakes, tris(hydroxymethyl)aminomethane and ellagic acid is 0.1:0.3:0.5. After the reaction is completed, filter, wash and dry to obtain ellagic acid-modified mica flakes;

[0060] (2) Mix sodium aluminate and deionized water according to the liquid ratio of 0.6 g: 5 mL to obtain a sodium aluminate solution; mix ellagic acid-modified mica flakes and deionized water according to the liquid ratio of 1 mg: 120 mL to obtain an ellagic acid-modified mica solution; add urea to the ellagic acid-modified mica solution and stir for 35 min to mix evenly, then add the sodium aluminate solution. Among them, the mass ratio of ellagic acid-modified mica, urea and sodium aluminate is 1 mg: 8 mg: 0.6 g. React at 150 °C for 3.5 h. After the reaction is completed, cool to room temperature and dry at 90 °C for 12 h to obtain the modified filler.

[0061] 2. Preparation method:

[0062] Mix the raw materials evenly and place them in a vacuum dryer at 80 °C, then place them in a mixer and knead at 200 °C for 10 min. After the kneading is completed, cool to room temperature and granulate to obtain a material with corrosion resistance and stress cracking resistance.

[0063] Comparative example 1:

[0064] The difference between this comparative example and Example 1 is that unmodified mica flakes are 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] Mix mica flakes and deionized water at a material-liquid ratio of 1 mg: 2 mL to obtain a mica flake dispersion; add tris (hydroxymethyl) aminomethane to the mica flake dispersion and mix evenly, then add ellagic acid and react at 65 °C for 6 h. Among them, the mass ratio of mica flakes, tris (hydroxymethyl) aminomethane and ellagic acid is 0.1: 0.25: 0.4. After the reaction is completed, filter, wash and dry 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 metaaluminate-modified mica flakes, which are prepared by the following method:

[0070] Mix mica flakes and deionized water at a material-liquid ratio of 1 mg: 2 mL to obtain a mica flake dispersion; mix sodium metaaluminate and deionized water at a material-liquid ratio of 0.57 g: 5 mL to obtain a sodium metaaluminate solution; add urea to the mica flake dispersion, and then add the sodium metaaluminate solution. Among them, the mass ratio of mica, urea and sodium metaaluminate is 1 mg: 6 mg: 0.57 g, react at 180 °C for 3 h. After the reaction is completed, cool to room temperature and dry at 80 °C for 12 h to obtain the modified filler.

[0071] Test example:

[0072] 1. Stress cracking resistance:

[0073] According to the test steps in the test method for environmental stress cracking of plastics polyethylene GB / T1842-2008, detect the environmental stress cracking time F of each group of specimens in an aqueous solution medium with a volume fraction of 10% of nonylphenol polyoxyethylene ether (TX-10) at 50 °C 50 , and the results are shown in Table 1.

[0074] 2. Corrosion resistance:

[0075] (1) Acid corrosion resistance

[0076] Take equal amounts of the composite materials prepared in Example 1 and Comparative Examples 1-4 respectively, soak them in concentrated sulfuric acid with a concentration of 98 wt% for 30 min, test the tensile strength of the composite material samples before and after soaking, and calculate the loss rate. The results are shown in Table 1;

[0077] (2) Alkali corrosion resistance

[0078] Take equal amounts of the composite materials prepared in Example 1 and Comparative Examples 1-4 respectively, soak them in a 10% sodium hydroxide solution for 30 min, test the tensile strength of the composite material samples before and after soaking, and calculate the loss rate. The results are shown in Table 1;

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

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

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

[0082]

[0083]

[0084] It can be seen from Table 1 that the materials prepared in the present invention using polypropylene and high-density polyethylene as the matrix and adding elastomers and modified fillers have good corrosion resistance and stress cracking resistance. Among them, when only mica is used as the filler, the environmental stress cracking time F of the prepared material 50 is 325 h. When using ellagic acid-modified mica as the modified filler, the environmental stress cracking time F of the prepared material 50 is 398 h. When using sodium metaaluminate-modified mica as the modified filler, the environmental stress cracking time F of the prepared material 50 is 376 h. The combination of ellagic acid and sodium metaaluminate-modified mica in the present invention has a synergistic effect on improving the stress cracking resistance of the material.

[0085] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A corrosion-resistant and stress-cracking-resistant material, characterized in that: The invention comprises the following raw materials in parts by weight: High-density polyethylene 45-55 parts, polypropylene 15-25 parts, elastomer 10-15 parts, modified filler 5-10 parts, lubricant 1-1.5 parts, antioxidant 1-2 parts; The modified filler is prepared by the following method: (1) dispersing mica flakes in deionized water to obtain a mica flake dispersion; adding tris(hydroxymethyl)aminomethane to the mica flake dispersion and mixing evenly, then adding ellagic acid to react, and after the reaction is completed, filtering, washing and drying to obtain ellagic acid-modified mica flakes; (2) dispersing ellagic acid modified mica flakes in water to obtain an ellagic acid modified mica solution; adding urea to the ellagic acid modified mica solution, and then adding a sodium aluminate solution to react, and after the reaction is completed, cooling and drying to obtain a modified filler.

2. The corrosion-resistant and stress-cracking-resistant material according to claim 1, characterized in that: In step (1), the 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).

3. The corrosion-resistant and stress-cracking-resistant material according to claim 1, characterized in that: In step (1), the reaction temperature is 50-80°C and the reaction time is 5-7h.

4. The corrosion-resistant and stress-cracking-resistant material according to claim 1, characterized in that: In step (2), the solid-liquid ratio of ellagic acid-modified mica and 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.

5. The corrosion-resistant and stress-cracking-resistant material according to claim 1, characterized in that: In step (2), the mass ratio of ellagic acid-modified mica, urea, and sodium aluminate in the sodium aluminate solution is 1 mg: (5-8) mg: (0.5-0.6) g.

6. The corrosion-resistant and stress-cracking-resistant material according to claim 1, characterized in that: In step (2), the reaction temperature is 150-200°C and the reaction time is 2.5-3.5h.

7. The corrosion-resistant and stress-cracking-resistant material according to claim 1, characterized in that: The elastomer is polyethylene-octene co-elastomer or polyethylene-vinyl acetate elastomer; the antioxidant is antioxidant 1010 or antioxidant 168; and the lubricant is stearate and / or polyethylene wax.

8. The method for preparing the corrosion-resistant and stress-cracking-resistant material according to any one of claims 1 to 7, characterized in that: The following steps are involved: The raw materials are mixed and dried, and then kneaded, cooled and granulated to obtain a corrosion-resistant and stress-cracking-resistant material.

9. The method for preparing the corrosion-resistant and stress-cracking-resistant material according to claim 8, characterized in that: The drying is vacuum drying, and the drying temperature is 60-80°C; the mixing temperature is 160-200°C, and the mixing time is 10-15min.

10. Use of the corrosion-resistant and stress-cracking-resistant material according to any one of claims 1 to 7 in the preparation of fuel tanks.

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