Nylon material containing modified calcium carbonate

Abstract

The invention belongs to the technical field of high polymer material preparation, and particularly relates to a nylon material containing modified calcium carbonate. The nylon material is prepared by the following steps: adding calcium carbonate into absolute ethyl alcohol, and adding stearic acid for reaction to obtain pretreated calcium carbonate; adding the pretreated calcium carbonate into an ethanol-water mixed solution, adding boric acid and urea, and carrying out ultrasonic dispersion and hydrothermal reaction to obtain a calcium carbonate loaded boron-nitrogen compound; dissolving polyether block polyamide in DMSO, adding furancarboxylic acid to react for 20-24 hours, adding the calcium carbonate loaded boron-nitrogen compound, stirring for 2-3 hours, and drying to obtain modified calcium carbonate; the preparation method comprises the following steps: carrying out melt blending on nylon and a maleimide end-capping substance to obtain modified nylon; 4, dry-mixing the modified nylon obtained in the step 4, an antioxidant and a lubricant, then adding modified calcium carbonate, carrying out melt blending, and carrying out extrusion granulation to obtain the nylon material containing modified calcium carbonate. The nylon material containing modified calcium carbonate prepared by the invention has the effects of rigidity-toughness balance and high thermal conductivity.

Description

Technical Field

[0001] This application belongs to the field of polymer material preparation technology, specifically relating to a nylon material containing modified calcium carbonate. Background Technology

[0002] Nylon, as one of the five major engineering plastics, is widely used in the automotive, electronics, and aerospace industries due to its advantages such as high strength, wear resistance, chemical corrosion resistance, and ease of processing. However, pure nylon has drawbacks such as high hygroscopicity, insufficient heat resistance, and high notch sensitivity, making it difficult to meet the demands of high-end applications for lightweight, multifunctionality, and long lifespan. Introducing inorganic fillers, such as calcium carbonate, through filler modification is an important way to improve the performance of nylon, but traditional technologies face the following core challenges: Existing modification methods mostly use coupling agents or polymer coatings to improve dispersibility, but the interfacial bonding is still mainly based on physical adsorption or hydrogen bonding, which is prone to dissociation under stress or high temperature, resulting in limited improvement in the tensile strength of the composite material and a significant decrease in toughness; moreover, the functions are limited, and it is difficult to coordinate rigidity and toughness, making it difficult to achieve a balance between rigidity and toughness. To address these challenges, there is an urgent need to develop a multifunctional nylon composite material that integrates strong interfacial bonding, rigidity and toughness balance, and green processing. Summary of the Invention

[0003] To address the aforementioned issues, the purpose of this application is to provide a nylon material containing modified calcium carbonate, which exhibits a balance of rigidity and toughness, as well as high thermal conductivity.

[0004] To achieve the above objectives, this application provides a nylon material containing modified calcium carbonate, which is prepared by the following steps: S1. Calcium carbonate is added to anhydrous ethanol and ultrasonically dispersed. Stearic acid is added to react, filtered, washed, and dried to obtain pretreated calcium carbonate. During the above process, the carboxyl group of stearate reacts with calcium ions to form hydrophobic calcium stearate, which is stably attached to the surface of calcium carbonate.

[0005] S2. Pretreated calcium carbonate was dispersed in an ethanol-water mixture, boric acid and urea were added, and after ultrasonic dispersion, a hydrothermal reaction was carried out. After centrifugation, washing and drying, calcium carbonate-supported boron-nitrogen complex was obtained. In the above process, stearic acid isolates water molecules from the surface of calcium carbonate through a hydrophobic membrane, reducing hygroscopicity, and disperses in a nonpolar medium through hydrophobic interactions. Boric acid reacts with urea under hydrothermal conditions, and urea decomposes to produce ammonia and isocyanate, which further condense with boric acid to form a precursor, and finally dehydrate to form a calcium carbonate-supported boron-nitrogen complex. Due to the unreacted boric acid / urea residue on the surface of the boron-nitrogen complex during the synthesis process, polar functional groups such as hydroxyl, amino, and boron-oxygen bonds are formed, which can form intermolecular hydrogen bonds with the hydroxyl groups remaining on the surface of calcium carbonate, anchoring it to the surface of calcium carbonate.

[0006] S3. Dissolve polyether block polyamide in DMSO, add furanyl carboxylic acid, heat to 80-85℃, add EDC and NHS to catalyze the amidation reaction for 20-24h, then add calcium carbonate-supported boron-nitrogen complex, stir for 2-3h, spray dry to obtain modified calcium carbonate. In the above process, the amino group of the polyether block polyamide and the carboxyl group of furanoic acid undergo a condensation reaction under the catalysis of EDC and NHS. EDC activates the carboxyl group of furanoic acid to form an unstable O-acyl isourea intermediate. After substitution by NHS, a stable N-hydroxysuccinimide ester is generated, which then reacts with the amino group of the polyether block polyamide to form an amide bond, forming a polyether block polyamide-furanoic acid complex. This complex forms hydrogen bonds with the polar groups on the surface of the calcium carbonate-supported boron nitrogen complex, and a coating layer is formed after spray drying.

[0007] S4. By weight, add 90-100 parts of nylon and 3-5 parts of maleimide end-capping compound to a twin-screw extruder and melt-blend to obtain modified nylon. In the above process, nylon and maleimide end-capped material are melt-blended, and the terminal amino groups of nylon undergo amidation reaction with maleimide groups, grafting the double bonds in maleimide onto the nylon backbone for subsequent reactions.

[0008] S5. By mass, dry mix the modified nylon obtained in step S4, 1-2 parts of antioxidant, and 1-2 parts of lubricant, add them to a twin-screw extruder, then add 5-6 parts of modified calcium carbonate for melt blending, extrusion granulation, and obtain a nylon material containing modified calcium carbonate.

[0009] In the above process, the double bonds in the modified nylon undergo a cyclization reaction with the cis-diene in the modified calcium carbonate to form covalent bonds.

[0010] Furthermore, the ultrasonic dispersion described in step S1 is performed with a power of 200-250W for 10-15 minutes.

[0011] Furthermore, the stearic acid has a mass ratio of 100:1-2 to calcium carbonate.

[0012] Furthermore, the reaction described in step S1 is carried out under the following conditions: at 60-70°C, stirred at 100-120 rpm for 2-3 hours.

[0013] Furthermore, the pretreated calcium carbonate, boric acid, and urea are used in a mass ratio of 100:10-15:30-45.

[0014] Furthermore, in step S2, the ultrasonic dispersion is performed at a power of 200-400W for a time of 15-20 minutes.

[0015] Furthermore, the hydrothermal reaction is carried out at a temperature of 180-185℃ for a time of 10-12 hours.

[0016] Furthermore, the polyether block polyamide has a molar ratio of 1:1.1-1.2 to furanylformic acid.

[0017] Furthermore, the molar ratio of EDC, NHS, and furanoic acid is 1-1.2:1-1.2:1.

[0018] Furthermore, the calcium carbonate-supported boron-nitrogen composite has a mass ratio of 0.8-1:1 to the polyether block polyamide.

[0019] Furthermore, in the spray drying process, the inlet air temperature is 150-160℃ and the outlet air temperature is 70-75℃.

[0020] Furthermore, the maleimide end-capped compound is a maleimide-terminated poly(N-isopropylacrylamide) or a maleimide-terminated caprolactam oligomer.

[0021] Furthermore, the twin-screw extruder described in steps S4 and S5 has the following parameters: feeding zone temperature of 220-230℃, compression zone temperature of 240-250℃, homogenization zone temperature of 250-260℃, die head temperature of 255-265℃, and screw speed of 300-500 rpm.

[0022] Furthermore, the antioxidant is antioxidant 1010 or antioxidant 1098.

[0023] Furthermore, the lubricant is ethylene bis-fatty acid amide or silicone powder.

[0024] In summary, this application has the following beneficial effects: This application utilizes stearic acid to hydrophobically treat calcium carbonate. The carboxyl groups of stearic acid form ionic / coordinate bonds with calcium ions on the surface of calcium carbonate, resulting in adsorption. The long-chain alkyl groups are arranged outwards to form a dense hydrophobic film. In the hydrothermal reaction system, urea hydrolysis generates ammonia, making the system weakly alkaline. Untreated calcium carbonate would come into full contact with water molecules and hydroxide ions, undergoing an alkaline dissolution reaction. Stearic acid hydrophobic treatment of calcium carbonate can block more than 90% of water molecules from directly contacting the calcium carbonate bulk, significantly slowing down the alkaline dissolution rate. After stearic acid treatment, 5%-10% of unoccupied calcium ion active sites remain on the surface. These active sites are positively charged and have strong interactions with the weakly negatively charged functional groups on the surface of the boron-nitrogen complex, becoming preferential anchoring sites for the boron-nitrogen complex and inducing its adsorption on the carbon. Calcium carbonate anchors on the surface to form a three-dimensional thermally conductive pathway; the polyamide segment of the polyether block polyamide has a structure similar to that of nylon, and they are tightly bound together by hydrogen bonds / intermolecular entanglement, exhibiting excellent compatibility. The flexible chain of the polyether segment alleviates the rigidity difference between the filler and nylon, reduces stress concentration, and increases toughness; furanic acid is covalently linked to the polyether block polyamide through an amidation reaction, and its furan ring can undergo a Diels-Alder cyclization reaction with modified nylon to form a multi-level interface of nylon-furan ring-polyether block polyamide-calcium carbonate-loaded boron-nitrogen composite, with significantly better interfacial bonding than simple physical mixing; the calcium carbonate-loaded boron-nitrogen composite enhances barrier properties and reduces crack propagation, while the flexible chain of the polyether block polyamide buffers impact and enhances toughness. The synergy of these three components makes the material both rigid and flexible. This solution utilizes a full-chain design to synergize the advantages of each material / step: low-cost reinforcement from calcium carbonate, thermal conductivity from calcium carbonate-loaded boron-nitrogen composites, interfacial compatibility and toughening from polyether block polyamides, enhanced interfacial bonding from maleimide and furan ring reactions, aging resistance from antioxidants, and synergistic processability from lubricants. Ultimately, this results in a high-strength, high-thermal-conductivity, aging-resistant, and easily processed nylon material suitable for electronics, automotive, and machinery industries. Detailed Implementation

[0025] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this invention.

[0026] The raw materials used in the specific embodiments of this application are analytical grade. Additionally: the polyether block polyamide was purchased from Longchi New Materials Co., Ltd., item number: PEBA MH 1657; the maleimide-terminated product is a maleimide-terminated caprolactam oligomer with a molecular weight of 1000; the calcium carbonate has a particle size of 1-2 μm; the nylon is nylon 6; and the MAL-PEG-MAL has a molecular weight of 2000.

[0027] DMSO: Dimethyl sulfoxide.

[0028] EDC: 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride.

[0029] NHS: N-hydroxysuccinimide.

[0030] Example 1 A nylon material containing modified calcium carbonate is prepared by the following steps: S1. Add 100g of calcium carbonate to 200ml of anhydrous ethanol and ultrasonically disperse (power 230W) for 15min. Add 1g of stearic acid and stir at 60℃ for 2h. Filter, wash 3 times with anhydrous ethanol, and dry at 80℃ for 4h to obtain pretreated calcium carbonate. S2. Disperse pretreated calcium carbonate in 400 ml of ethanol-water mixture (ethanol to water volume ratio 2:1), add boric acid and urea (mass ratio of pretreated calcium carbonate, boric acid and urea is 100:15:30), ultrasonically disperse (power 300W, time 15min), and then hydrothermally react at 180℃ for 12 h. Centrifuge (speed 1200rpm), take the precipitate, wash it 3 times with ethanol-water mixture, and dry it at 80℃ for 3 h to obtain calcium carbonate supported boron nitrogen complex. S3. Dissolve polyether block polyamide in DMSO, add furanyl carboxylic acid (polyether block polyamide: furanyl carboxylic acid molar ratio = 1:1.1), heat to 80℃, add EDC and NHS to catalyze the amidation reaction for 24h (EDC and NHS molar ratio to furanyl carboxylic acid is 1:1:1), then add calcium carbonate supported boron-nitrogen complex (calcium carbonate supported boron-nitrogen complex to polyether block polyamide mass ratio is 0.8:1), stir (speed 250 rpm) for 2h, spray dry for 4h (inlet air 150℃, outlet air 70℃) to obtain modified calcium carbonate; S4. By weight, add 90 parts of nylon and 3 parts of maleimide-terminated caprolactam oligomer to a twin-screw extruder (feeding zone temperature 220℃, compression zone temperature 240℃, homogenization zone temperature 250℃, die head temperature 255℃, screw speed 300rpm) and melt-blend for 10 min to obtain modified nylon. S5. By mass, dry mix (1 part antioxidant 1010 and 1 part silicone powder) obtained in step S4 for 5 min (1000 rpm), add to a twin-screw extruder, then add 5 parts modified calcium carbonate for melt blending, extrusion granulation, and obtain a nylon material containing modified calcium carbonate.

[0031] Example 2 A nylon material containing modified calcium carbonate is prepared by the following steps: S1. Add 100g of calcium carbonate to 200ml of anhydrous ethanol and ultrasonically disperse (power 200W) for 15min. Add 1g of stearic acid and stir at 60℃ for 2h. Filter, wash 3 times with anhydrous ethanol, and dry at 80℃ for 4h to obtain pretreated calcium carbonate. S2. Pretreated calcium carbonate was dispersed in 400 ml of ethanol-water mixture (ethanol to water volume ratio 2:1), boric acid and urea were added (pretreated calcium carbonate, boric acid and urea mass ratio 100:10:30), ultrasonically dispersed (power 200W, time 15min), and then hydrothermally reacted at 180℃ for 12 h. After centrifugation (speed 1200rpm), the precipitate was washed 3 times with ethanol-water mixture and dried at 80℃ for 3 h to obtain calcium carbonate-supported boron-nitrogen complex. S3. Dissolve polyether block polyamide in DMSO, add furanyl carboxylic acid (polyether block polyamide: furanyl carboxylic acid molar ratio = 1:1.2), heat to 80℃, add EDC and NHS to catalyze the amidation reaction for 24h (EDC and NHS to furanyl carboxylic acid molar ratio is 1.1:1.1:1), then add calcium carbonate supported boron nitrogen complex (calcium carbonate supported boron nitrogen complex to polyether block polyamide mass ratio is 0.9:1), stir (speed 250 rpm) for 2h, spray dry for 4h (inlet air 150℃, outlet air 70℃) to obtain modified calcium carbonate; S4. By weight, add 95 parts of nylon and 4 parts of maleimide-terminated caprolactam oligomer to a twin-screw extruder (feeding zone temperature 220℃, compression zone temperature 240℃, homogenization zone temperature 250℃, die head temperature 255℃, screw speed 300rpm) and melt-blend for 10 min to obtain modified nylon. S5. By mass, dry mix (1 part antioxidant 1010 and 1 part silicone powder) obtained in step S4 for 5 min, add to a twin-screw extruder, then add 6 parts modified calcium carbonate for melt blending, extrusion granulation, and obtain a nylon material containing modified calcium carbonate.

[0032] Example 3 A nylon material containing modified calcium carbonate is prepared by the following steps: S1. Add 100g of calcium carbonate to 200ml of anhydrous ethanol and ultrasonically disperse (power 250W) for 15min. Add 1g of stearic acid and stir at 60℃ for 2h. Filter, wash 3 times with anhydrous ethanol, and dry at 80℃ for 4h to obtain pretreated calcium carbonate. S2. Pretreated calcium carbonate was dispersed in 400 ml of ethanol-water mixture (ethanol to water volume ratio 2:1), boric acid and urea were added (pretreated calcium carbonate, boric acid and urea mass ratio 100:10:45), ultrasonically dispersed (power 200W, time 15min), and then hydrothermally reacted at 180℃ for 12 h. After centrifugation (speed 1200rpm), the precipitate was washed 3 times with ethanol-water mixture and dried at 80℃ for 3 h to obtain calcium carbonate-supported boron-nitrogen complex. S3. Dissolve polyether block polyamide in DMSO, add furanyl carboxylic acid (polyether block polyamide: furanyl carboxylic acid molar ratio = 1:1.2), heat to 80℃, add EDC and NHS to catalyze the amidation reaction for 24h (EDC and NHS molar ratio to furanyl carboxylic acid is 1.2:1.2:1), then add calcium carbonate-supported boron-nitrogen complex (calcium carbonate-supported boron-nitrogen complex to polyether block polyamide mass ratio is 1:1), stir (250 rpm) for 2h, spray dry for 4h (inlet air 150℃, outlet air 70℃) to obtain modified calcium carbonate; S4. By weight, add 95 parts of nylon and 4 parts of maleimide-terminated caprolactam oligomer to a twin-screw extruder (feeding zone temperature 230℃, compression zone temperature 250℃, homogenization zone temperature 260℃, die head temperature 265℃, screw speed 300rpm) and melt-blend for 10 min to obtain modified nylon. S5. By mass, dry mix (1 part antioxidant 1010 and 1 part silicone powder) obtained in step S4 for 5 min, add to a twin-screw extruder, then add 6 parts modified calcium carbonate for melt blending, extrusion granulation, and obtain a nylon material containing modified calcium carbonate.

[0033] Compare with Example 1 Compared with Example 3, this comparative example uses tartaric acid instead of stearic acid.

[0034] Compare with Example 2 The difference between this comparative example and Example 3 is that pretreated calcium carbonate was used instead of modified calcium carbonate.

[0035] Compare with Example 3 The difference between this comparative example and Example 3 is that MAL-PEG-MAL is used instead of maleimide-terminated caprolactam oligomer.

[0036] Performance testing Functional tests were conducted on a nylon material containing modified calcium carbonate prepared in Examples 1-3 and Control Examples 1-3.

[0037] Tensile strength test: Refer to standard GB / T 1040.2-2022, use a universal testing machine for testing, at room temperature, tensile rate of 5 mm / min, to test tensile strength; Bending performance test: Referencing standard GB / T 9341-2008, the three-point bending method was used, with a span of 64 mm and a speed of 2 mm / min to measure the bending modulus. Impact strength test: The impact strength is tested using a pendulum impact testing machine in accordance with the standard GB / T 1843-2008. Thermal conductivity testing: The laser scintillation method was used for testing at temperatures of 25℃ / 100℃. The sample thickness was 1 mm. The results are shown in Table 1. Table 1 Group Tensile strength (MPa) Flexural modulus GPa Impact strength kJ / m² Thermal conductivity W / (m·K) Example 1 147 3.8 63 0.51 Example 2 151 4.1 68 0.58 Example 3 143 3.6 60 0.47 Compare with Example 1 113 3.3 51 0.41 Compare with Example 2 136 3.1 49 0.32 Compare with Example 3 107 3.4 55 0.45 As shown in Table 1, the nylon material containing modified calcium carbonate prepared in this application has excellent mechanical properties and thermal conductivity. The table shows that the tensile strength, impact strength, and flexural modulus are all relatively high, indicating a good balance between rigidity and toughness in the nylon material. The high thermal conductivity indicates good thermal conductivity. The nylon material containing modified calcium carbonate prepared in this application exhibits a balance of thermal conductivity, rigidity, and toughness. In contrast to Example 3, Comparative Example 1 uses tartaric acid instead of stearic acid. The two carboxyl groups of tartaric acid form water-soluble calcium tartrate, covering the surface active sites. This causes the calcium carbonate-loaded boron-nitrogen complex to lose its anchoring basis and fail to form a uniform thermally conductive network. Although the polar bonds of tartaric acid are beneficial for forming hydrogen bonds, they are prone to over-adsorption, forming thick and uneven coatings. In the coating, some furan groups are encapsulated inside the shell, preventing them from contacting the maleimide groups of the nylon matrix, resulting in reduced interfacial bonding, tensile strength, and thermal conductivity. In Comparative Example 2, compared to Example 3, pretreated calcium carbonate was used directly, and the results showed that the nylon material containing modified calcium carbonate prepared in Comparative Example 2 had poor thermal conductivity. In Comparative Example 3, compared to Example 3, MAL-PEG-MAL was used instead of the maleimide-terminated caprolactam oligomer. Although both contained maleimide groups, MAL-PEG-MAL had poor compatibility with nylon, leading to phase separation and a decrease in overall performance. This indicates that MAL-PEG-MAL cannot replace the maleimide-terminated material of this application, and that Comparative Example 3 is inferior to Example 3.

[0038] The above description is merely an example and illustration of the concept of this application. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the inventive concept or exceed the scope defined in the claims, they should all fall within the protection scope of this application.

Claims

1. A nylon material containing modified calcium carbonate, characterized in that, It is prepared by the following steps: S1. Calcium carbonate is added to anhydrous ethanol and ultrasonically dispersed. Stearic acid is added to react, filtered, washed, and dried to obtain pretreated calcium carbonate. S2. Pretreated calcium carbonate was dispersed in an ethanol-water mixture, boric acid and urea were added, and after ultrasonic dispersion, a hydrothermal reaction was carried out. After centrifugation, washing and drying, calcium carbonate-supported boron-nitrogen complex was obtained. S3. Dissolve polyether block polyamide in DMSO, add furanyl carboxylic acid, heat to 80-85℃, add EDC and NHS to catalyze the amidation reaction for 20-24h, then add calcium carbonate-supported boron-nitrogen complex, stir for 2-3h, spray dry to obtain modified calcium carbonate. S4. By weight, add 90-100 parts of nylon and 3-5 parts of maleimide end-capping compound to a twin-screw extruder and melt-blend to obtain modified nylon. S5. By mass, dry mix the modified nylon obtained in step S4, 1-2 parts of antioxidant, and 1-2 parts of lubricant, add them to a twin-screw extruder, then add 5-6 parts of modified calcium carbonate for melt blending, extrusion granulation, and obtain a nylon material containing modified calcium carbonate.

2. The nylon material containing modified calcium carbonate according to claim 1, characterized in that, The stearic acid has a mass ratio of 100:1-2 with calcium carbonate.

3. The nylon material containing modified calcium carbonate according to claim 1, characterized in that, The pretreatment of calcium carbonate, boric acid, and urea is carried out in a mass ratio of 100:10-15:30-45.

4. The nylon material containing modified calcium carbonate according to claim 1, characterized in that, The polyether block polyamide has a molar ratio of 1:1.1-1.2 to furanyl carboxylic acid.

5. The nylon material containing modified calcium carbonate according to claim 1, characterized in that, The molar ratio of EDC, NHS, and furanoic acid is 1-1.2:1-1.2:

1.

6. The nylon material containing modified calcium carbonate according to claim 1, characterized in that, The calcium carbonate-supported boron-nitrogen composite has a mass ratio of 0.8-1:1 to polyether block polyamide.

7. The nylon material containing modified calcium carbonate according to claim 1, characterized in that, The maleimide-terminated product is a maleimide-terminated poly(N-isopropylacrylamide) or a maleimide-terminated caprolactam oligomer.

8. The nylon material containing modified calcium carbonate according to claim 1, characterized in that, The twin-screw extruder described in steps S4 and S5 has the following parameters: feeding zone temperature 220-230℃, compression zone temperature 240-250℃, homogenization zone temperature 250-260℃, die head temperature 255-265℃, and screw speed 300-500 rpm.

9. A nylon material containing modified calcium carbonate according to claim 1, characterized in that, The ultrasonic dispersion in step S2 is performed at a power of 200-400W for 15-20 minutes.

10. A nylon material containing modified calcium carbonate according to claim 1, characterized in that, The hydrothermal reaction is carried out at a temperature of 180-185℃ for 10-12 hours.