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

Abstract

The invention relates to an environment-friendly self-repairing polypropylene material. The environment-friendly self-repairing polypropylene material is prepared by compounding polypropylene, modified silicon dioxide and an itaconic acid-acrylic acid copolymer, the preparation method comprises the following steps: firstly, carrying out hydroxylation treatment on silicon dioxide, and then reacting with carboxymethyl chitosan, so that the carboxymethyl chitosan is introduced into the modified silicon dioxide; the carboxymethyl chitosan is introduced into the modified silicon dioxide, so that a large amount of hydroxyl can be introduced into the modified silicon dioxide, more hydrogen bond sites can be formed, and a high-density hydrogen bond network can be formed between the modified silicon dioxide and a large amount of carboxyl, amino and other polar groups in the itaconic acid-acrylic acid copolymer, the repairing agent and other components; and when the polypropylene material is scratched and damaged, polar groups at the scratched part are quickly recombined through the hydrogen-bond interaction, so that self-repairing is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of polypropylene materials, and in particular to an environmentally friendly self-repairing polypropylene material and a preparation method thereof. Background Art

[0002] Polypropylene materials are widely used due to their excellent comprehensive performance and low cost, but their inherent lack of toughness makes the products prone to microcracks and damage under long-term use or stress, which seriously affects the service life and poses a safety hazard. The traditional method of reinforcement by adding inorganic fillers often aggravates the brittleness of the material due to filler agglomeration and poor interface compatibility, and cannot solve the problem of damage accumulation. Some existing self-healing polypropylene technologies, such as those that rely on embedded microcapsules to encapsulate repair agents or require external application of heat, light and other stimuli to trigger repair, generally have limitations such as low repair efficiency, harsh conditions, limited number of repairs, and inability to regenerate after the repair agent is exhausted. More importantly, the repair agents used in these technologies are mostly synthetic chemicals that are difficult to degrade, with complex preparation processes, insufficient environmental friendliness and sustainability, and it is difficult to meet increasingly stringent environmental protection requirements and considerations on material biocompatibility.

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

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

[0005]

[0006] Wherein, the modified silicon dioxide is a product obtained by grafting carboxymethyl chitosan onto hydroxylated silicon dioxide.

[0007] Specifically, carboxymethyl chitosan, a naturally renewable polysaccharide derivative, can be specifically degraded by chitosanase, secreted by soil microorganisms, to produce low-molecular-weight oligosaccharides or monosaccharides, thus avoiding the environmental residue issues associated with traditional silane coupling agent-modified materials. Furthermore, itaconic acid-acrylic acid copolymers can be degraded synergistically through biodegradation and photooxidative degradation, achieving environmentally friendly post-waste 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 1,000-50,000.

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

[0011] Furthermore, the other auxiliary agents are selected from one or more of a repairing agent, a dispersant, a lubricant, and a nucleating agent.

[0012] Furthermore, the lubricant is selected from one or more of silicones, amides, polyethylenes, stearic acids or esters.

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

[0014] The present invention also provides a method for preparing the environmentally friendly self-repairing polypropylene material, which comprises the following steps:

[0015] S1, mixing hydroxylated silica and carboxymethyl chitosan, heating and reacting to obtain modified silica;

[0016] S2. Evenly mix the modified silica with other ingredients 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] Furthermore, in step S1, the mass ratio of the hydroxylated silica to the carboxymethyl chitosan is 1-5:2-5.

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

[0020] The environmentally friendly self-repairing 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, thereby introducing the carboxymethyl chitosan into the modified silica.

[0021] On the one hand, the introduction of carboxymethyl chitosan into the modified silica can improve the interfacial properties of the silica. The hydrophobic segments in the carboxymethyl chitosan can improve the compatibility between the modified silica and ingredients such as polypropylene and itaconic acid-acrylic acid copolymer, significantly reducing interfacial tension and preventing the agglomeration of the modified silica. The long chain structure of the carboxymethyl chitosan can be physically entangled with ingredients such as polypropylene and itaconic acid-acrylic acid copolymer, making the components more tightly bonded, which is beneficial to improving the mechanical properties and scratch resistance of the polypropylene material.

[0022] On the other hand, the introduction of carboxymethyl chitosan into the modified silica can introduce a large number of hydroxyl groups into the modified silica, forming more hydrogen bonding sites. This can form a high-density hydrogen bonding network with a large number of polar groups such as carboxyl and amino groups in components such as itaconic acid-acrylic acid copolymer and repair agents, resulting in stronger hydrogen bonding and a tighter bond between the components. When the polypropylene material is scratched and damaged, the polar groups at the scratch are prompted to quickly reorganize through hydrogen bonding, thereby achieving self-repair.

[0023] In addition, due to the introduction of itaconic acid-acrylic acid copolymer and carboxymethyl chitosan polymer flexible chain segments, the polypropylene material of the present invention can accelerate the rapid diffusion and migration of polymer molecular segments in the scratch area to the scratch area under heating conditions, so that a large number of hydrogen bonds are quickly re-formed between polar groups, and the carboxymethyl chitosan segments on the surface of the modified silica are promoted to re-entangle and combine with other components, thereby realizing rapid and effective self-repair of the polypropylene material. DETAILED DESCRIPTION

[0024] In order to more clearly illustrate the technical solutions of the present invention, the following examples are given. Unless otherwise stated, the raw materials, reactions and post-processing methods mentioned in the examples are common raw materials on the market and technical methods well known to those skilled in the art.

[0025] The terms "preferred," "preferably," "more preferred," and the like, used herein, refer to embodiments of the invention that may provide certain benefits under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, nor is it intended to exclude other embodiments from the scope of the invention.

[0026] It should be understood that, except in any operating examples, or where otherwise indicated, all numbers expressing, for example, quantities of ingredients used in the specification and claims are to be understood as being modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and appended claims are approximations that may vary depending upon the desired properties to be obtained by the present invention.

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

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

[0029] Silica, nanosilica, S776198, was purchased from MacLean.

[0030] Carboxymethyl chitosan, C902396, was purchased from Maclean.

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

[0032] The repair agent, polyethyleneimine, 767274, MW 250,000, was purchased from Macklin.

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

[0034] Lubricant, silicone powder.

[0035] The “parts” in the embodiments of the present invention refer to parts by mass.

[0036] Example 1

[0037] An environmentally friendly self-repairing polypropylene material, the raw materials of which include the following components in parts by weight:

[0038]

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

[0040] S1-1, soaking silica in a 2 mol / L hydrochloric acid solution, stirring at 75°C for 2 hours, centrifuging, washing, and drying to obtain hydroxylated silica;

[0041] S1-2, using ethanol as solvent, mixing hydroxylated silica and carboxymethyl chitosan, heating to 70°C for reaction for 3 hours, filtering, and washing to obtain modified silica;

[0042] Wherein, the mass ratio of the hydroxylated silica to carboxymethyl chitosan is 2:3;

[0043] S2. Evenly mix the modified silica with other ingredients according to the above-mentioned mass fractions, melt and extrude the mixture into granules at 170° C. through a twin-screw extruder to obtain the self-repairing scratch-resistant polypropylene.

[0044] Example 2

[0045] An environmentally friendly self-repairing polypropylene material, the raw materials of which include the following components in parts by weight:

[0046]

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

[0048] S1-1, soaking silica in a 2 mol / L hydrochloric acid solution, stirring at 75°C for 2 hours, centrifuging, washing, and drying to obtain hydroxylated silica;

[0049] S1-2, using ethanol as solvent, mixing hydroxylated silica and carboxymethyl chitosan, heating to 70°C for reaction for 3 hours, filtering, and washing to obtain modified silica;

[0050] Wherein, the mass ratio of the hydroxylated silica to carboxymethyl chitosan is 2:3;

[0051] S2. Evenly mix the modified silica with other ingredients according to the above-mentioned mass fractions, melt and extrude the mixture into granules at 170° C. through a twin-screw extruder to obtain the self-repairing scratch-resistant polypropylene.

[0052] Example 3

[0053] An environmentally friendly self-repairing polypropylene material, the raw materials of which include the following components in parts by weight:

[0054]

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

[0056] S1-1, soaking silica in a 2 mol / L hydrochloric acid solution, stirring at 75°C for 2 hours, centrifuging, washing, and drying to obtain hydroxylated silica;

[0057] S1-2, using ethanol as solvent, mixing hydroxylated silica and carboxymethyl chitosan, heating to 70°C for reaction for 3 hours, filtering, and washing to obtain modified silica;

[0058] Wherein, the mass ratio of the hydroxylated silica to carboxymethyl chitosan is 2:3;

[0059] S2. Evenly mix the modified silica with other ingredients according to the above-mentioned mass fractions, melt and extrude the mixture into granules at 170° C. through a twin-screw extruder to obtain the self-repairing scratch-resistant polypropylene.

[0060] Comparative Example 1

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

[0062] Comparative Example 2

[0063] A polypropylene material. This comparative example differs from Example 1 in that steps S1-1 and S1-2 are removed, and modified silica of equal mass is replaced with silica modified with a silane coupling agent as a component of the polypropylene material. Other components and preparation methods are the same.

[0064] The method for preparing silicon dioxide modified with a silane coupling agent comprises the following steps:

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

[0066] Test Example 1

[0067] The performance tests were performed on the polypropylene materials prepared in Examples 1-3 and Comparative Examples 1-2.

[0068] Scratch resistance and self-repair performance tests were conducted using the PV3952 Volkswagen scratch resistance test. The polypropylene materials prepared in Examples 1-3 and Comparative Examples 1-2 were injection-molded into leather-grain panels and subjected to scratch tests at 25°C and 35°C, respectively. The scratch force used in the tests was 10N.

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

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

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

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

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

[0074]

[0075] Table 1 shows that the color difference between Examples 1-3 at 25°C and 35°C is smaller than that of the polypropylene resin in Comparative Examples 1-2, indicating that carboxymethyl chitosan grafted onto the silica surface effectively improves the scratch resistance and self-repair ability of the material after surface damage. Furthermore, the lack of carboxymethyl chitosan in the polypropylene material in Comparative Example 2 reduces the hydrogen bond density between the various components of the polypropylene material, resulting in a decrease in the self-repair effect. Furthermore, the tensile strength of Examples 1-3 is significantly superior to that of Comparative Examples 1-2, demonstrating that the technical solution of the present invention can enhance 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 embodied 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 illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

[0077] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. An environmentally friendly self-repairing polypropylene material, characterized in that: The raw materials include the following components in parts by mass: Wherein, the modified silicon dioxide is a product obtained by grafting carboxymethyl chitosan onto hydroxylated silicon dioxide.

2. The environmentally friendly self-repairing 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-repairing polypropylene material according to claim 1, characterized in that: The molecular weight of the itaconic acid-acrylic acid copolymer is 1,000-50,000.

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

5. The environmentally friendly self-repairing polypropylene material according to claim 1, characterized in that: The other auxiliary agents are selected from one or more of a repairing agent, a dispersant, a lubricant, and a nucleating agent.

6. The environmentally friendly self-repairing polypropylene material according to claim 6, characterized in that: The lubricant is selected from one or more of silicones, amides, polyethylenes, stearic acids or esters.

7. The environmentally friendly self-repairing polypropylene material according to claim 6, characterized in that: The repair agent is selected from one or more of polyethyleneimine, glycerol polyester, and polyethylene glycol.

8. The method for preparing the environmentally friendly self-repairing polypropylene material according to any one of claims 1 to 7, characterized in that: The steps include: S1, mixing hydroxylated silica and carboxymethyl chitosan, heating and reacting to obtain modified silica; S2. Evenly mix the modified silica with other ingredients to obtain an environmentally friendly self-healing polypropylene material.

9. The method for preparing the environmentally friendly self-repairing polypropylene material according to claim 8, characterized in that: In step S1, the temperature of the heating reaction is 65-85°C.

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

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