Environment-friendly self-repairing polypropylene material and preparation method thereof

Abstract

The application relates to an environment-friendly self-repairing polypropylene material, which is prepared by compounding polypropylene, modified silicon dioxide and itaconic acid-acrylic acid copolymer; firstly, the silicon dioxide is subjected to hydroxylation treatment, and then is reacted with carboxymethyl chitosan, so that the carboxymethyl chitosan is introduced into the modified silicon dioxide; as the carboxymethyl chitosan is introduced into the modified silicon dioxide, a large number of hydroxyl groups can be introduced into the modified silicon dioxide, more hydrogen bond sites can be formed, a high-density hydrogen bond network can be formed between the itaconic acid-acrylic acid copolymer and a large number of polar groups such as carboxyl groups and amino groups in the repairing agent and other components, stronger hydrogen bond action is generated, the components are more closely combined, and when the polypropylene material is damaged by scratching, the polar groups at the scratch position are rapidly recombined through hydrogen bond action, so that self-repairing is realized.

Description

Technical Field

[0001] This invention relates to the field of polypropylene materials technology, and in particular to an environmentally friendly self-healing polypropylene material and its preparation method. Background Technology

[0002] Polypropylene (PP) materials are widely used due to their excellent comprehensive performance and low cost. However, their inherent lack of toughness makes products prone to microcracks and damage under long-term use or stress, seriously affecting their service life and posing safety hazards. Traditional methods of reinforcing with inorganic fillers often exacerbate the brittleness of the material due to filler agglomeration and poor interfacial compatibility, and cannot solve the problem of damage accumulation. Existing self-healing PP technologies, such as those relying on microencapsulated repair agents or requiring external stimulation such as heat or light to trigger repair, generally suffer from limitations such as low repair efficiency, demanding conditions, limited number of repair cycles, and the inability to regenerate the repair agent after it is depleted. More importantly, the repair agents used in these technologies are mostly difficult-to-degrade synthetic chemicals with complex preparation processes, insufficient environmental friendliness and sustainability, and difficulty in meeting increasingly stringent environmental protection requirements and considerations for material biocompatibility.

[0003] Therefore, developing a polypropylene material solution that can efficiently self-heal under mild conditions, has good interfacial bonding, and also has excellent environmental compatibility has become a key issue that urgently needs to be addressed. Summary of the Invention

[0004] Therefore, it is necessary to provide an environmentally friendly, self-healing polypropylene material, the raw materials of which include the following components in parts by weight:

[0005]

[0006] The modified silica is a product obtained by grafting carboxymethyl chitosan onto hydroxylated silica.

[0007] Specifically, carboxymethyl chitosan, as a natural renewable polysaccharide derivative, can be specifically degraded by chitosanase secreted by microorganisms in the soil, generating low-molecular-weight oligosaccharides or monosaccharides, thus avoiding the environmental residue problems of traditional silane coupling agent-modified materials. Simultaneously, itaconic acid-acrylic acid copolymers can achieve environmentally friendly decomposition after material disposal through the synergistic effect of biodegradation and photo-oxidative degradation.

[0008] Furthermore, the melt index of the polypropylene is 20-100 g / 10 min.

[0009] Furthermore, the molecular weight of the itaconic acid-acrylic acid copolymer is 1000-50000.

[0010] Furthermore, the heat stabilizer is one or more of the following: phenolic heat stabilizers, amine heat stabilizers, phosphite heat stabilizers, and semi-hindered phenolic heat stabilizers.

[0011] Furthermore, the other additives are selected from one or more of the following: repair agents, dispersants, lubricants, and nucleating agents.

[0012] Furthermore, the lubricant is selected from one or more of silicone, amide, polyethylene, stearic acid, or ester compounds.

[0013] Furthermore, the repair agent is selected from one or more of polyethyleneimine, glycerol polyester, and polyethylene glycol.

[0014] This invention also provides a method for preparing the environmentally friendly self-healing polypropylene material, which includes the following steps:

[0015] S1. Hydroxylated silica is mixed with carboxymethyl chitosan and heated to react, thus obtaining modified silica;

[0016] S2. Mix the modified silica with other components evenly to obtain an environmentally friendly self-healing polypropylene material.

[0017] Furthermore, in step S1, the temperature of the heating reaction is 65-85°C.

[0018] Further, in step S1, the mass ratio of the hydroxylated silica to carboxymethyl chitosan is 1-5:2-5.

[0019] The present invention has the following beneficial effects:

[0020] The environmentally friendly self-healing polypropylene material of the present invention is compounded with polypropylene, modified silica, and itaconic acid-acrylic acid copolymer; first, the silica is hydroxylated, and then reacted with carboxymethyl chitosan to introduce carboxymethyl chitosan into the modified silica.

[0021] On the one hand, the introduction of carboxymethyl chitosan into modified silica can improve the interfacial properties of silica. The hydrophobic segments in carboxymethyl chitosan can improve the compatibility between modified silica and components such as polypropylene and itaconic acid-acrylic acid copolymer, significantly reduce interfacial tension, and prevent the phenomenon of agglomeration of modified silica. On the other hand, the long chain structure of carboxymethyl chitosan can physically entangle with components such as polypropylene and itaconic acid-acrylic acid copolymer, making the combination between the components tighter, which is beneficial to improving the mechanical properties and scratch resistance of polypropylene materials.

[0022] On the other hand, by introducing carboxymethyl chitosan into modified silica, a large number of hydroxyl groups can be introduced into the modified silica, which can form more hydrogen bond sites. This allows for the formation of a high-density hydrogen bond network between the large number of carboxyl and amino polar groups in components such as itaconic acid-acrylic acid copolymer and repair agents, resulting in stronger hydrogen bonding. The combination between the components is tighter, and when the polypropylene material is scratched or damaged, the polar groups at the scratch site are rapidly reorganized through hydrogen bonding, thereby achieving self-repair.

[0023] Furthermore, the polypropylene material of the present invention, due to the introduction of itaconic acid-acrylic acid copolymer and carboxymethyl chitosan polymer flexible segments, can accelerate the rapid diffusion and migration of polymer molecular segments in the scratched area to the scratched area under heating conditions, so as to rapidly reform a large number of hydrogen bonds between polar groups, and promote the re-entanglement and bonding of carboxymethyl chitosan segments on the modified silica surface with other components, thereby achieving rapid and effective self-repair of the polypropylene material. Detailed Implementation

[0024] To more clearly illustrate the technical solution of the present invention, the following embodiments are provided. Unless otherwise stated, the raw materials, reactions, and post-processing methods appearing in the embodiments are all commercially available raw materials and technical methods well known to those skilled in the art.

[0025] The terms "preferred," "more preferably," and "more suitable" used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.

[0026] It should be understood that, except in any operational instance or otherwise indicated, all figures representing the amounts of ingredients used, for example, in the specification and claims, should be understood to be modified in all cases by the term "about". Therefore, unless otherwise stated, the numerical parameters set forth in the following specification and appended claims are approximations varying with the desired performance to be obtained according to the invention.

[0027] Polypropylene resin, PP K9026, melt index 25g / 10min, purchased from Yanshan Petrochemical.

[0028] Itaconic acid-acrylic acid copolymer, relative molecular weight: 1000-50000, HC0604, purchased from Shanghai Zhouyuan Biotechnology Co., Ltd.

[0029] Silica, nano silica, S776198, purchased from Maclean's.

[0030] Carboxymethyl chitosan, C902396, purchased from Maclean's.

[0031] Heat stabilizer, pentaerythritol β-(3-,5-di-tert-butyl-4-hydroxyphenyl)propionate.

[0032] Repair agent, polyethyleneimine, 767274, MW 250,000, purchased from Maclean's.

[0033] Dispersant, polyacrylic acid, P822497, MW~2000, purchased from Maclean's.

[0034] Lubricant, silicone powder.

[0035] In the embodiments of this invention, "parts" refers to parts by mass.

[0036] Example 1

[0037] An environmentally friendly, self-healing polypropylene material, comprising the following components in parts by weight:

[0038]

[0039] The preparation method of the above-mentioned environmentally friendly self-healing polypropylene material includes the following steps:

[0040] S1-1. Immerse silica in a 2 mol / L hydrochloric acid solution, stir at 75°C for 2 h, centrifuge, wash, and dry to obtain hydroxylated silica.

[0041] S1-2. Using ethanol as a solvent, hydroxylated silica and carboxymethyl chitosan were mixed, heated to 70°C and reacted for 3 hours. After filtration and washing, modified silica was obtained.

[0042] The mass ratio of hydroxylated silica to carboxymethyl chitosan is 2:3.

[0043] S2. According to the above-mentioned mass proportions, the modified silica is mixed evenly with other components, and then melted, extruded and granulated at 170°C using a twin-screw extruder to obtain the self-healing and scratch-resistant polypropylene.

[0044] Example 2

[0045] An environmentally friendly, self-healing polypropylene material, comprising the following components in parts by weight:

[0046]

[0047] The preparation method of the above-mentioned environmentally friendly self-healing polypropylene material includes the following steps:

[0048] S1-1. Immerse silica in a 2 mol / L hydrochloric acid solution, stir at 75°C for 2 h, centrifuge, wash, and dry to obtain hydroxylated silica.

[0049] S1-2. Using ethanol as a solvent, hydroxylated silica and carboxymethyl chitosan were mixed, heated to 70°C and reacted for 3 hours. After filtration and washing, modified silica was obtained.

[0050] The mass ratio of hydroxylated silica to carboxymethyl chitosan is 2:3.

[0051] S2. According to the above-mentioned mass proportions, the modified silica is mixed evenly with other components, and then melted, extruded and granulated at 170°C using a twin-screw extruder to obtain the self-healing and scratch-resistant polypropylene.

[0052] Example 3

[0053] An environmentally friendly, self-healing polypropylene material, comprising the following components in parts by weight:

[0054]

[0055] The preparation method of the above-mentioned environmentally friendly self-healing polypropylene material includes the following steps:

[0056] S1-1. Immerse silica in a 2 mol / L hydrochloric acid solution, stir at 75°C for 2 h, centrifuge, wash, and dry to obtain hydroxylated silica.

[0057] S1-2. Using ethanol as a solvent, hydroxylated silica and carboxymethyl chitosan were mixed, heated to 70°C and reacted for 3 hours. After filtration and washing, modified silica was obtained.

[0058] The mass ratio of hydroxylated silica to carboxymethyl chitosan is 2:3.

[0059] S2. According to the above-mentioned mass proportions, the modified silica is mixed evenly with other components, and then melted, extruded and granulated at 170°C using a twin-screw extruder to obtain the self-healing and scratch-resistant polypropylene.

[0060] Comparative Example 1

[0061] A polypropylene material, the difference between this comparative example and Example 1 is that steps S1-2 are removed, and only hydroxylated silica is used as a component of the polypropylene material, while other components and preparation methods are the same.

[0062] Comparative Example 2

[0063] A polypropylene material, the difference between this comparative example and Example 1 is that: steps S1-1 and S1-2 are removed, and silane coupling agent modified silica is used to replace an equal mass of modified silica as a component of the polypropylene material, while other components and preparation methods are the same;

[0064] The method for preparing silica modified with a silane coupling agent includes the following steps:

[0065] Using ethanol as a solvent, 10 parts of silica and 1 part of silane coupling agent KH560 were stirred for 3 hours and reacted at a constant temperature of 70°C for 3 hours. The mixture was then filtered, washed, and dried to obtain the product.

[0066] Test Example 1

[0067] The performance of the polypropylene materials prepared in Examples 1-3 and Comparative Examples 1-2 was tested.

[0068] Scratch resistance and self-healing performance tests: The scratch resistance test was conducted using the PV3952 Volkswagen scratch resistance tester. The polypropylene materials prepared in Examples 1-3 and Comparative Examples 1-2 were injection molded into leather-textured samples at 25℃ and 35℃ respectively. The scratch force used in the test was 10N.

[0069] Among them, the color difference value of the polypropylene material surface before scratching and 0 min after scratching was tested under the condition of 25℃. The smaller the color difference value, the closer the polypropylene surface is to the state before scratching after scratching, and the better its scratch resistance.

[0070] The color difference value of the polypropylene material surface before and 30 minutes after scratching was tested under conditions of 25℃ and 35℃. The smaller the color difference value, the closer the polypropylene surface is to the state before scratching, and the better its self-healing performance.

[0071] Tensile property test: The test was conducted in accordance with ISO 527-2, with a sample size of 150×10×4mm and a tensile speed of 10mm / min.

[0072] The test results are shown in Table 1.

[0073] Table 1. Performance test results of polypropylene materials in Examples 1-3 and Comparative Examples 1-2.

[0074]

[0075] Table 1 shows that the color difference of the polypropylene resins in Examples 1-3 at 25℃ and 35℃ is smaller than that in Comparative Examples 1-2, indicating that grafting carboxymethyl chitosan onto the silica surface can effectively improve the scratch resistance and self-healing ability of the material surface after damage. Furthermore, the polypropylene material in Comparative Example 2, due to the lack of carboxymethyl chitosan, has a lower hydrogen bond density between its components, resulting in a decreased self-healing effect. In addition, the tensile strength of Examples 1-3 is significantly better than that of Comparative Examples 1-2, demonstrating that the technical solution of this invention can improve the mechanical properties of polypropylene materials.

[0076] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0077] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An environmentally friendly, self-healing polypropylene material, characterized in that, The raw materials consist of the following components in parts by weight: 50-60 parts of polypropylene 5-10 parts of modified silica 2-4 parts of itaconic acid-acrylic acid copolymer Heat stabilizer 0.5-1 part Other auxiliary agents, 1-2 parts; The modified silica is a product obtained by grafting carboxymethyl chitosan onto hydroxylated silica. The other additives are repair agents, dispersants, and lubricants; The repair agent is polyethyleneimine.

2. The environmentally friendly self-healing polypropylene material according to claim 1, characterized in that, The melt index of the polypropylene is 20-100 g / 10 min.

3. The environmentally friendly self-healing polypropylene material according to claim 1, characterized in that, The molecular weight of the itaconic acid-acrylic acid copolymer is 1000-50000.

4. The environmentally friendly self-healing polypropylene material according to claim 1, characterized in that, The heat stabilizer is one or more of phenolic heat stabilizers, amine heat stabilizers, and phosphite heat stabilizers.

5. The environmentally friendly self-healing polypropylene material according to claim 1, characterized in that, The lubricant is selected from one or more of silicone, amide, and stearic acid compounds.

6. The method for preparing the environmentally friendly self-healing polypropylene material according to any one of claims 1-5, characterized in that, Includes the following steps: S1. Hydroxylated silica is mixed with carboxymethyl chitosan and heated to react, thus obtaining modified silica; S2. Mix the modified silica with other components evenly to obtain an environmentally friendly self-healing polypropylene material.

7. The method for preparing the environmentally friendly self-healing polypropylene material according to claim 6, characterized in that, In step S1, the temperature of the heating reaction is 65-85℃.

8. The method for preparing the environmentally friendly self-healing polypropylene material according to claim 6, characterized in that, In step S1, the mass ratio of hydroxylated silica to carboxymethyl chitosan is 1-5:2-5.

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