Polycarbonate modified composite material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of polymer composite materials, and particularly relates to a polycarbonate modified composite material as well as a preparation method and application thereof, and the polycarbonate modified composite material comprises 60-85 parts of a PC base material, 10-30 parts of a bio-based monomer, 1-8 parts of surface modified nano cellulose and 0.1-2 parts of a transesterification catalyst. According to the polycarbonate modified composite material as well as the preparation method and the application thereof provided by the invention, chemical bonding of a bio-based monomer and a PC main chain is realized through transesterification, phase separation is avoided, and the core pain point of traditional blending modification is solved; the biodegradation rate is increased by 30% or above compared with pure PC, and meanwhile, the excellent mechanical properties (the tensile strength is larger than or equal to 60 MPa, and the notch impact strength is larger than or equal to 5 kJ / m) of PC are reserved; the melt flow rate is increased by more than 25%, the processing energy consumption is reduced, and the application scene is widened; the carboxylic acid modified nano cellulose and the block copolymer form a synergistic network, so that the mechanical property, the thermal stability and the degradation uniformity are synchronously improved.

Description

Technical Field

[0001] This invention belongs to the field of polymer composite materials technology, and particularly relates to polycarbonate modified composite materials, their preparation methods and applications. Background Technology

[0002] Polycarbonate (PC), as a high-performance engineering plastic, boasts advantages such as high strength, high toughness, good light transmittance, and excellent heat resistance, and is widely used in electronics, automotive parts, medical devices, and packaging materials. However, traditional PC materials mainly rely on fossil resources for synthesis and are difficult to degrade in the natural environment. Extensive use of PC materials can easily cause "white pollution," which is inconsistent with current global environmental policies and the needs of sustainable development.

[0003] To address the environmental concerns associated with PC materials, current technologies often employ blending and modification with bio-based materials (such as polylactic acid and castor oil derivatives). However, due to the significant polarity difference and poor compatibility between bio-based materials and PC, direct blending can lead to phase separation in the composite material, resulting in a significant decrease in mechanical properties (such as impact strength and tensile strength) and a deterioration in processing fluidity (increased melt viscosity), thus failing to meet the requirements of practical applications.

[0004] Existing improvement schemes mainly include: 1) adding compatibilizers (such as maleic anhydride grafted polymers) to improve interfacial compatibility, but compatibilizers can only adjust the interface through physical action, with limited effect and cannot fundamentally solve the problem of insufficient degradation rate; 2) using chemical grafting to graft bio-based monomers onto PC segments, but existing grafting reactions mostly rely on free radical polymerization, which easily leads to degradation of the PC backbone, and the grafting sites are random, making it difficult to form a stable block structure; 3) adding inorganic nanofillers (such as nanocellulose) to enhance mechanical properties, but unmodified nanocellulose is prone to agglomeration and has weak binding force with the PC interface, and cannot exert a synergistic enhancement effect.

[0005] Therefore, how to overcome the compatibility bottleneck between bio-based materials and PC, and significantly improve its biodegradability and processing fluidity while retaining the excellent mechanical properties of PC, so as to achieve a "balance between environmental protection and practicality", is a technical problem that urgently needs to be solved in the current field of PC modification. Summary of the Invention

[0006] The purpose of this invention is to provide polycarbonate modified composite materials, their preparation methods and applications, and to solve the technical problems of poor compatibility, low degradation rate and poor processing flowability of bio-based modified PC materials in the prior art.

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

[0008] The polycarbonate-modified composite material provided in this embodiment of the invention comprises the following components in parts by weight:

[0009] 60-85 parts of PC substrate;

[0010] 10-30 parts of bio-based monomer, wherein the bio-based monomer is a polylactic acid oligomer or a ricinoleic acid derivative;

[0011] 1-8 parts of surface-modified nanocellulose, wherein the nanocellulose is modified by carboxylation and the surface carboxyl content is 0.5-3 mmol / g;

[0012] 0.1-2 parts of transesterification catalyst;

[0013] The bio-based monomer is grafted onto the terminal or side hydroxyl sites of the PC backbone via transesterification to form a "PC-bio-based carboxylic acid ester" block copolymer; the surface-modified nanocellulose and the block copolymer form a synergistic network through hydrogen bonds and carboxyl-ester group interactions.

[0014] Further, the number average molecular weight of the polylactic acid oligomer is 500-5000 Da; the ricinoleic acid derivative is one or more of glycidyl ricinoleate, methyl ricinoleate, or ethyl ricinoleate.

[0015] Furthermore, the preparation process of the surface-modified nanocellulose is as follows: nanocellulose is reacted with a carboxylic acid modifier at 60-100℃ for 2-8 hours. The carboxylic acid modifier is one or more of maleic anhydride, citric acid or succinic anhydride, and the amount of modifier is 5-20% of the mass of nanocellulose.

[0016] Furthermore, the transesterification catalyst is selected from one or more of tetrabutyl titanate, stannous octoate, zinc acetate, and dibutyltin oxide.

[0017] Furthermore, the transesterification reaction conditions are as follows: reaction temperature 220-260℃, reaction time 10-60 min, reaction system pressure 0.05-0.3 MPa, and graft polymerization is carried out in a twin-screw extruder.

[0018] Furthermore, the weight parts of each component are as follows: 70-80 parts of PC substrate, 15-25 parts of bio-based monomer, 3-6 parts of surface-modified nanocellulose, and 0.5-1.5 parts of transesterification catalyst.

[0019] Furthermore, the grafting rate of the bio-based monomer on the PC backbone is 5-20%, and the grafting rate is calculated by nuclear magnetic resonance hydrogen spectroscopy (¹H-NMR).

[0020] The particle size of the surface-modified nanocellulose is 10-100 nm in diameter and 1-5 μm in length, as determined by freeze-drying-scanning electron microscopy.

[0021] Furthermore, the polycarbonate modified composite material has a tensile strength ≥60MPa, a notched impact strength ≥5kJ / m², and a flexural modulus ≥2500MPa, as tested according to GB / T1040.1-2006, GB / T1843-2008, and GB / T9341-2008 standards.

[0022] Based on the same inventive concept, this application also provides a method for preparing polycarbonate modified composite materials, comprising the following steps:

[0023] (1) Preparation of surface-modified nanocellulose: Nanocellulose and carboxylic acid modifier are mixed at a mass ratio of 100:5-20 and reacted at 60-100℃ for 2-8h. After filtration, washing and drying, surface-modified nanocellulose with a surface carboxyl content of 0.5-3mmol / g is obtained; The carboxylic acid modifier is selected from one or more of maleic anhydride, citric acid and succinic anhydride.

[0024] (2) Premixing: 60-85 parts by weight of PC substrate, 10-30 parts by weight of bio-based monomer, 1-8 parts by weight of surface-modified nanocellulose obtained in step (1), and 0.1-2 parts by weight of transesterification catalyst are added to a high-speed mixer and mixed at 1000-1500 r / min for 5-10 min to obtain a premix; the bio-based monomer is selected from polylactic acid oligomer (number average molecular weight 500-5000 Da), ricinoleic acid derivatives (one or more of glycidyl ricinoleate, methyl ricinoleate, and ethyl ricinoleate); the transesterification catalyst is selected from one or more of tetrabutyl titanate, stannous octoate, zinc acetate, and dibutyltin oxide.

[0025] (3) Ester exchange graft polymerization and molding: The premix obtained in step (2) is added to a twin-screw extruder and reacted for 10-60 min at a reaction temperature of 220-260℃ and a reaction system pressure of 0.05-0.3MPa. This allows the bio-based monomers to be grafted onto the terminal or side hydroxyl sites of the PC main chain through ester exchange reaction, forming a "PC-bio-based carboxylic acid ester" block copolymer. At the same time, the surface-modified nanocellulose forms a synergistic network with the block copolymer through hydrogen bonding and carboxyl-ester group interaction. After the reaction, the polycarbonate modified composite material is obtained by extrusion, granulation and injection molding.

[0026] Based on the same inventive concept, this application also provides the application of polycarbonate modified composite materials, including the following steps:

[0027] The polycarbonate-modified composite material is a composite material containing a "PC-bio-based carboxylic acid ester" block copolymer and a carboxylic acid-modified nanocellulose synergistic network, and meets the following requirements: biodegradability (tested according to GB / T19277.1-2011 standard) is more than 30% higher than that of pure PC; melt flow rate (230℃ / 2.16kg, tested according to GB / T3682-2018 standard) is more than 25% higher than that of pure PC; tensile strength is ≥60MPa and notched impact strength is ≥5kJ / m² (tested according to GB / T1040.1-2006 and GB / T1843-2008 standards, respectively).

[0028] In the preparation of disposable environmentally friendly packaging products, the high biodegradability and processing fluidity of the composite material are utilized to obtain packaging with a thickness of 0.1-1mm through injection molding or vacuum forming. The biodegradability of the packaging in the natural environment is ≥35% within 6-12 months.

[0029] When preparing lightweight automotive interior parts, the high strength and low volatility of the composite material (VOC content ≤100μgC / g, tested according to GB / T27630-2011 standard) are utilized to obtain door interior panels and dashboard brackets through injection molding or extrusion molding. The flexural modulus of the interior parts is ≥2500MPa (tested according to GB / T9341-2008 standard).

[0030] When manufacturing electronic appliance housings / stands, the heat resistance (heat distortion temperature ≥120℃, tested according to GB / T1634.2-2004 standard) and mechanical stability of the composite material are utilized to obtain laptop housings and charging pile stands through injection molding.

[0031] Compared with the prior art, the beneficial effects of this invention are as follows:

[0032] 1. Significantly improved compatibility: Chemical bonding between bio-based monomers and the PC backbone is achieved through transesterification, avoiding phase separation and solving the core pain point of traditional blending modification;

[0033] 2. Balance between environmental protection and practicality: The biodegradability rate is more than 30% higher than that of pure PC, while retaining the excellent mechanical properties of PC (tensile strength ≥60MPa, notched impact strength ≥5kJ / m²).

[0034] 3. Improved processing fluidity: Melt flow rate is increased by more than 25%, reducing processing energy consumption and expanding application scenarios;

[0035] 4. Synergistic enhancement effect: Carboxylic acid modified nanocellulose and block copolymers form a synergistic network, which simultaneously improves mechanical properties, thermal stability and degradation uniformity. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0037] Example 1: Polylactic acid oligomer grafted modified PC composite material (for disposable environmentally friendly packaging)

[0038] 1. Raw material formula (by weight)

[0039]

[0040] 2. Preparation steps

[0041] (1) Preparation of surface-modified nanocellulose:

[0042] Four parts of nanocellulose and 0.4 parts of maleic anhydride (10% of the mass of nanocellulose) were added to a reaction vessel, and deionized water was used as the dispersion medium. The mixture was stirred at 80°C for 4 hours. After the reaction, the mixture was filtered, washed with deionized water until the pH of the filtrate was 7, and then vacuum dried at 60°C for 12 hours to obtain surface-modified nanocellulose with a surface carboxyl content of 1.5 mmol / g (tested by potentiometric titration). The particle size was 25-45 nm in diameter and 1.8-2.5 μm in length (tested by freeze-drying-scanning electron microscopy).

[0043] (2) Premixed:

[0044] 75 parts of PC substrate, 20 parts of polylactic acid oligomer, 4 parts of surface-modified nanocellulose, and 1 part of tetrabutyl titanate were added to a high-speed mixer and mixed at 1200 r / min for 8 min to obtain a uniform premix.

[0045] (3) Ester exchange graft polymerization and molding:

[0046] The premixed material was added to a twin-screw extruder (screw length-to-diameter ratio 40:1), and the temperatures of each section were set as follows: feeding section 200℃, compression section 230℃, reaction section 240℃, and die head section 235℃. The reaction system pressure was 0.1MPa, the screw speed was 180r / min, and the reaction time was 30min. After extrusion granulation, the granules were dried at 120℃ for 4h and then injection molded into standard test specimens using an injection molding machine (injection temperature 245℃, mold temperature 80℃).

[0047] 3. Performance Test Results

[0048]

[0049] 4. Application Verification

[0050] The composite material was used to prepare a 0.5mm thick disposable food packaging box. After being placed in a natural soil environment for 8 months, the biodegradation rate reached 38%, meeting the requirements for disposable environmentally friendly packaging products.

[0051] Example 2:

[0052] Castor oil acid derivative compound grafted modified PC composite material (for lightweight automotive interiors)

[0053] 1. Raw material formula (by weight)

[0054]

[0055] 2. Preparation steps

[0056] (1) Preparation of surface-modified nanocellulose:

[0057] Two parts of nanocellulose and 0.2 parts of citric acid (10% of the mass of nanocellulose) were added to a reaction vessel. An ethanol-water mixture (volume ratio 1:1) was used as the dispersion medium, and the mixture was stirred at 70°C for 6 hours. After the reaction, the mixture was filtered, washed three times with ethanol, and vacuum dried at 50°C for 10 hours to obtain surface-modified nanocellulose with a surface carboxyl content of 0.8 mmol / g (as determined by potentiometric titration). The particle size was 45-75 nm in diameter and 2.5-3.8 μm in length (as determined by freeze-drying-scanning electron microscopy).

[0058] (2) Premixed:

[0059] 65 parts of PC substrate, 28 parts of bio-based monomer compound, 2 parts of surface-modified nanocellulose, and 0.3 parts of stannous octoate were added to a high-speed mixer and mixed at 1000 r / min for 10 min to obtain a uniform premix.

[0060] (3) Ester exchange graft polymerization and molding:

[0061] The premixed material was added to a twin-screw extruder (screw length-to-diameter ratio 40:1), and the temperatures of each section were set as follows: feeding section 190℃, compression section 220℃, reaction section 230℃, and die head section 225℃. The reaction system pressure was 0.08MPa, the screw speed was 160r / min, and the reaction time was 40min. After extrusion granulation, the granules were dried at 110℃ for 5h and then injection molded into automotive interior parts samples (door interior panel model, injection temperature 235℃, mold temperature 70℃).

[0062] 3. Performance Test Results

[0063]

[0064] 4. Application Verification

[0065] The prepared door interior panel sample has a flexural modulus of 2580MPa and a VOC content of 78μgC / g, meeting the requirements of low volatility and high strength for lightweight automotive interior parts. After assembly testing, it meets the assembly standards of the automotive industry.

[0066] Example 3:

[0067] Ethyl castor oil-grafted modified PC composite material (for electronic and electrical appliance housings)

[0068] 1. Raw material formula (by weight)

[0069]

[0070] 2. Preparation steps

[0071] (1) Preparation of surface-modified nanocellulose:

[0072] Seven parts of nanocellulose and 1.12 parts of succinic anhydride (16% of the mass of nanocellulose) were added to a reaction vessel. Using N,N-dimethylformamide as the dispersion medium, the mixture was stirred at 90°C for 3 hours. After the reaction, the mixture was filtered, washed three times with acetone, and dried under vacuum at 70°C for 8 hours to obtain surface-modified nanocellulose with a surface carboxyl content of 2.8 mmol / g (as determined by potentiometric titration). The particle size was 18-35 nm in diameter and 1.2-1.8 μm in length (as determined by freeze-drying-scanning electron microscopy).

[0073] (2) Premixed:

[0074] 82 parts of PC substrate, 12 parts of ethyl castor oil, 7 parts of surface-modified nanocellulose, and 1.8 parts of dibutyltin oxide were added to a high-speed mixer and mixed at 1500 r / min for 5 min to obtain a uniform premix.

[0075] (3) Ester exchange graft polymerization and molding:

[0076] The premixed material was added to a twin-screw extruder (screw length-to-diameter ratio 40:1), and the temperatures of each section were set as follows: feeding section 210℃, compression section 240℃, reaction section 250℃, and die head section 245℃. The reaction system pressure was 0.2MPa, the screw speed was 200r / min, and the reaction time was 20min. After extrusion granulation, the granules were dried at 130℃ for 3 hours and then injection molded into laptop casing samples using an injection molding machine (injection temperature 250℃, mold temperature 90℃).

[0077] 3. Performance Test Results

[0078]

[0079] 4. Application Verification

[0080] The prepared laptop shell has a bending modulus of 2860MPa and a VOC content of 92μgC / g, meeting the high strength requirements of laptops. After assembly testing, it meets the laptop industry standards.

[0081] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A polycarbonate-modified composite material, characterized in that, Includes the following components by weight: 60-85 parts of PC substrate; 10-30 parts of bio-based monomer, wherein the bio-based monomer is a polylactic acid oligomer or a ricinoleic acid derivative; 1-8 parts of surface-modified nanocellulose, wherein the nanocellulose is modified by carboxylation and the surface carboxyl content is 0.5-3 mmol / g; 0.1-2 parts of transesterification catalyst; The bio-based monomer is grafted onto the terminal or side hydroxyl sites of the PC backbone via transesterification to form a "PC-bio-based carboxylic acid ester" block copolymer; the surface-modified nanocellulose and the block copolymer form a synergistic network through hydrogen bonds and carboxyl-ester group interactions.

2. The polycarbonate-modified composite material according to claim 1, characterized in that, The number-average molecular weight of the polylactic acid oligomer is 500-5000 Da; the ricinoleic acid derivative is one or more of glycidyl ricinoleate, methyl ricinoleate, or ethyl ricinoleate.

3. The polycarbonate-modified composite material according to claim 1, characterized in that, The preparation process of the surface-modified nanocellulose is as follows: nanocellulose is reacted with a carboxylic acid modifier at 60-100℃ for 2-8 hours. The carboxylic acid modifier is one or more of maleic anhydride, citric acid or succinic anhydride, and the amount of modifier is 5-20% of the mass of nanocellulose.

4. The polycarbonate-modified composite material according to claim 1, characterized in that, The transesterification catalyst is selected from one or more of tetrabutyl titanate, stannous octoate, zinc acetate, and dibutyltin oxide.

5. The polycarbonate-modified composite material according to claim 1, characterized in that, The transesterification reaction conditions are as follows: reaction temperature 220-260℃, reaction time 10-60min, reaction system pressure 0.05-0.3MPa, and graft polymerization is carried out in a twin-screw extruder.

6. The polycarbonate-modified composite material according to claim 1, characterized in that, The components are in the following weight parts: 70-80 parts PC substrate, 15-25 parts bio-based monomer, 3-6 parts surface-modified nanocellulose, and 0.5-1.5 parts transesterification catalyst.

7. The polycarbonate-modified composite material according to claim 1, characterized in that, The grafting rate of the bio-based monomer on the PC backbone is 5-20%, and the grafting rate is calculated by nuclear magnetic resonance hydrogen spectroscopy (¹H-NMR). The particle size of the surface-modified nanocellulose is 10-100 nm in diameter and 1-5 μm in length, as determined by freeze-drying-scanning electron microscopy.

8. The polycarbonate-modified composite material according to claim 1, characterized in that, The polycarbonate-modified composite material has a tensile strength ≥60MPa, a notched impact strength ≥5kJ / m², and a flexural modulus ≥2500MPa, as tested according to GB / T1040.1-2006, GB / T1843-2008, and GB / T9341-2008 standards.

9. A method for preparing a polycarbonate-modified composite material, based on the polycarbonate-modified composite material according to claim 1, characterized in that, Includes the following steps: (1) Preparation of surface-modified nanocellulose: Nanocellulose and carboxylic acid modifier are mixed at a mass ratio of 100:5-20 and reacted at 60-100℃ for 2-8h. After filtration, washing and drying, surface-modified nanocellulose with a surface carboxyl content of 0.5-3mmol / g is obtained; The carboxylic acid modifier is selected from one or more of maleic anhydride, citric acid and succinic anhydride. (2) Premixing: 60-85 parts by weight of PC substrate, 10-30 parts by weight of bio-based monomer, 1-8 parts by weight of surface-modified nanocellulose obtained in step (1), and 0.1-2 parts by weight of transesterification catalyst are added to a high-speed mixer and mixed at 1000-1500 r / min for 5-10 min to obtain a premix; the bio-based monomer is selected from polylactic acid oligomer (number average molecular weight 500-5000 Da), ricinoleic acid derivatives (one or more of glycidyl ricinoleate, methyl ricinoleate, and ethyl ricinoleate); the transesterification catalyst is selected from one or more of tetrabutyl titanate, stannous octoate, zinc acetate, and dibutyltin oxide. (3) Ester exchange graft polymerization and molding: The premix obtained in step (2) is added to a twin-screw extruder and reacted for 10-60 min at a reaction temperature of 220-260℃ and a reaction system pressure of 0.05-0.3MPa. This allows the bio-based monomers to be grafted onto the terminal or side hydroxyl sites of the PC main chain through ester exchange reaction, forming a "PC-bio-based carboxylic acid ester" block copolymer. At the same time, the surface-modified nanocellulose forms a synergistic network with the block copolymer through hydrogen bonding and carboxyl-ester group interaction. After the reaction, the polycarbonate modified composite material is obtained by extrusion, granulation and injection molding.

10. An application of a polycarbonate-modified composite material, based on the polycarbonate-modified composite material of claim 1, characterized in that: The polycarbonate-modified composite material is a composite material containing a "PC-bio-based carboxylic acid ester" block copolymer and a carboxylic acid-modified nanocellulose synergistic network, and meets the following requirements: biodegradability (tested according to GB / T19277.1-2011 standard) is more than 30% higher than that of pure PC; melt flow rate (230℃ / 2.16kg, tested according to GB / T3682-2018 standard) is more than 25% higher than that of pure PC; tensile strength is ≥60MPa; and notched impact strength is ≥5kJ / m² (tested according to GB / T1040.1-2006 and GB / T1843-2008 standards, respectively). In the preparation of disposable environmentally friendly packaging products, the high biodegradability and processing fluidity of the composite material are utilized to obtain packaging with a thickness of 0.1-1mm through injection molding or vacuum forming. The biodegradability of the packaging in the natural environment is ≥35% within 6-12 months. When preparing lightweight automotive interior parts, the high strength and low volatility of the composite material (VOC content ≤100μgC / g, tested according to GB / T27630-2011 standard) are utilized to obtain door interior panels and dashboard brackets through injection molding or extrusion molding. The flexural modulus of the interior parts is ≥2500MPa (tested according to GB / T9341-2008 standard). When manufacturing electronic appliance housings / stands, the heat resistance (heat distortion temperature ≥120℃, tested according to GB / T1634.2-2004 standard) and mechanical stability of the composite material are utilized to obtain laptop housings and charging pile stands through injection molding.

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