Preparation method of bifunctional modified calcium carbonate with capacity and reinforcement

Abstract

The application discloses a preparation method of a bifunctional modified calcium carbonate with capacity and enhancement effects, and belongs to the technical field of biodegradable materials. Firstly, 4-aminomethyl benzoic acid solution is prepared and sprayed on the surface of pretreated calcium carbonate, and high-speed heating and mixing are conducted to obtain pretreated calcium carbonate. Secondly, folic acid is reacted in a solvent to obtain an active ester solution; the active ester solution is slowly added and dropped in a high-speed mixer while stirring to conduct a reaction, and modified calcium carbonate is obtained after drying. Finally, polybutylene adipate terephthalate and the modified calcium carbonate are subjected to high-speed mixing to obtain polybutylene adipate terephthalate / folic acid-4-aminomethyl benzoic acid-calcium carbonate mixture; the mixture is melt-extruded by using a double-screw extruder to obtain bifunctional modified calcium carbonate, the tensile strength of which is increased to 30.36 Mpa, and the elongation at break is increased to 698%; the contact angle of the prepared folic acid-4-aminomethyl benzoic acid-calcium carbonate is increased to 137.5 degrees, and the activation rate is increased to 99.10%.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of biodegradable materials, and particularly relates to a preparation method of a dual-functional modified calcium carbonate with compatibilization and reinforcement effects and application of the dual-functional modified calcium carbonate in polybutylene adipate terephthalate (PBAT). BACKGROUND

[0002] Traditional plastic products have brought convenience and high-end value to people's life due to their stable chemical properties, but in recent years, the increasingly serious environmental problem of plastic pollution has attracted global attention. In recent years, polybutylene adipate terephthalate (PBAT) as a new biodegradable material widely concerned on the market has attracted the attention of enterprises and researchers. Polybutylene adipate terephthalate (PBAT) has good ductility, toughness and elasticity due to the aliphatic chain segment (BA segment) and aromatic chain segment (BT segment) in the molecular chain. However, the current polybutylene adipate terephthalate (PBAT) has the disadvantages of high production cost and poor thermodynamic performance, which limits its large-scale use. Therefore, the main goal of the current research work is to reduce the production cost of polybutylene adipate terephthalate (PBAT) composite material and improve its comprehensive performance and broaden its application range.

[0003] Calcium carbonate has the advantages of low cost, high whiteness, low hardness and low oil absorption, and is often used as an inorganic filler in polymer modification to increase the size stability, rigidity, heat resistance and other properties of the material. However, the surface of calcium carbonate is hydrophilic and oleophobic, and when it is blended with polybutylene adipate terephthalate (PBAT), the two phases have poor compatibility due to the large difference in polarity. In order to disperse calcium carbonate uniformly in the polymer matrix, improve the compatibility between calcium carbonate and the polymer matrix, increase the filling amount of calcium carbonate in the polymer and improve the processing and mechanical properties of the composite material, effective modification process and modifier must be used to modify the surface of calcium carbonate so that it can play a good toughening and reinforcing role as a filler. Moreover, the modified calcium carbonate has low production cost and high mechanical properties when blended with polybutylene adipate terephthalate (PBAT), which has great research value.

[0004] At present, the commonly used calcium carbonate surface modifier mainly can be divided into coupling agent class, surface active agent class, composite modifier class, super dispersant class and inorganic matter class and so on. Patent CN115124827A adds coupling agent with calcium carbonate, degradable polymer prepolymer, mixes under high speed stirring, and then cools and stirs to obtain modified calcium carbonate, but the conventional silane coupling agent has few hydroxyl groups, it is difficult to react with calcium carbonate, and the coupling agent which can successfully modify calcium carbonate is high in price, and it is difficult to produce on a large scale in industry. The modified calcium carbonate in patent CN117264382A is calcium carbonate modified by hydrophobic modifier stearic acid and calcium stearate. SUMMARY

[0005] In order to solve the problems of low strength and poor compatibility of calcium carbonate, and realize that after blending of polybutylene adipate terephthalate (PBAT), the processing performance and mechanical properties of the composite material are significantly improved, the application provides a preparation method of dual-functional modified calcium carbonate with compatibilization and reinforcement.

[0006] The preparation operation steps of the dual-functional modified calcium carbonate with compatibilization and reinforcement are as follows:

[0007] (1) Preparation of 4-aminomethyl benzoic acid-calcium carbonate (PAMBA-CaCO3)

[0008] (1.1) According to the mass volume ratio of 10g:100mL, 4-aminomethyl benzoic acid (PAMBA) is added to deionized water, stirred uniformly, and 4-aminomethyl benzoic acid (PAMBA) solution is obtained;

[0009] (1.2) According to the mass ratio (1.5-2):100, 4-aminomethyl benzoic acid (PAMBA) solution is sprayed to the surface of pretreated calcium carbonate, high-speed mixing, drying, and pretreated calcium carbonate (PAMBA-CaCO3) is obtained;

[0010] (2) Preparation of folic acid-4-aminomethyl benzoic acid-calcium carbonate (FA-PAMBA-CaCO3)

[0011] (2.1) According to the mass ratio (5-10):100, folic acid (FA) is added to dimethyl sulfoxide (DMSO) solvent, and ultrasonic is performed until complete dissolution, to obtain folic acid solution;

[0012] (2.2) According to the mass ratio (0.01-0.02):100, dicyclohexyl carbodiimide (DCC) and N-hydroxysuccinimide (NHS) are added to the folic acid solution, and magnetic stirring reaction is carried out at room temperature, and the reaction by-product is removed by filtration, to obtain an active ester solution;

[0013] (2.3) In a high-speed mixer, drop the active ester solution into 4-aminomethylbenzoic acid-calcium carbonate (PAMBA-CaCO3) at a drop rate of 80-100 mL / h while stirring, and dry the obtained reaction product at 80°C for 6 h to prepare folic acid-4-aminomethylbenzoic acid-calcium carbonate (FA-PAMBA-CaCO3);

[0014] (3) Preparation of the mixture

[0015] The polybutylene adipate terephthalate (PBAT) and the folic acid-4-aminomethylbenzoic acid-calcium carbonate (FA-PAMBA-CaCO3) are mixed at a mass ratio of (5-10):100 to prepare the mixture;

[0016] (4) Preparation of the bifunctional modified calcium carbonate

[0017] The mixture is melt-extruded in a twin-screw extruder to obtain the bifunctional modified calcium carbonate;

[0018] The bifunctional modified calcium carbonate is heavy calcium powder with a particle size of 800-1000 mesh, a tensile strength of 28.68 Mpa-30.36 Mpa, an elongation at break of 602%-698%, and a contact angle of 89.00°-94.60°.

[0019] The further defined technical solutions are as follows:

[0020] In step (1.2), the high-speed mixing conditions are: temperature 70°C, rotation speed 1000 rpm / min, and mixing time 30 min.

[0021] In step (2.1), the ultrasonic conditions are: room temperature, and ultrasonic time 30 min.

[0022] In step (2.2), the magnetic stirring is carried out at room temperature for 8-10 h.

[0023] In step (2.3), the high-speed mixing conditions are: room temperature, rotation speed 1000 rpm / min, and mixing time 8 h.

[0024] In step (2.3), the drop conditions are: drop rate 80-100 mL / h, and reaction time 6-8 h.

[0025] In step (3), the high-speed mixing conditions are: temperature 45-65°C, and time 1-3 h.

[0026] In step (4), the melt-extrusion conditions are: screw rotation speed 200-300 rpm, feeding speed 5-7 Hz, and extrusion temperature zone set to 160, 165, 170, 175, 180, 185, 190, 190, 190, 185, 180°C.

[0027] The beneficial technical effects of the present application are embodied in the following aspects:

[0028] (1) The present application utilizes esterification-coordination mechanism, as shown in (b) of Figure 2 , 4-aminomethyl benzoic acid ionizes 4-aminomethyl benzoate, which can be adsorbed on the surface of calcium carbonate more uniformly by high-speed stirring; at the same time, as shown in Figure 3 , the carboxyl group of 4-aminomethyl benzoic acid and the hydroxyl group of calcium carbonate react to form an ester, and compared with the unmodified calcium carbonate, the contact angle of 4-aminomethyl benzoic acid-calcium carbonate modified by esterification-coordination mechanism increases from 0° to 115.4°, and the activation rate increases from 1.58% to 81.06%, thereby improving the hydrophilicity of calcium carbonate, improving its application in non-polar or hydrophobic matrix, and improving the irreversible agglomeration caused by the intermolecular hydrogen bond due to the surface hydroxyl group.

[0029] (2) The present application utilizes amide-hydrogen bond mechanism, as shown in Figure 4 , the introduced amino group of 4-aminomethyl benzoic acid reacts with the carboxyl group of FA to produce an amide bond as a hydrogen bond donor; as shown in Figure 5 , the amide bond can produce hydrogen bond interaction with the surface of polybutylene adipate terephthalate, and compared with the polybutylene adipate terephthalate / leaf acid-4-aminomethyl benzoic acid-calcium carbonate modified by amide-hydrogen bond mechanism, the contact angle increases from 80.18° to 94.60°, further improving the interfacial compatibility of calcium carbonate and PBAT; the tensile strength of polybutylene adipate terephthalate / leaf acid-4-aminomethyl benzoic acid-calcium carbonate composite material increases from 18.53Mpa to 30.36Mpa compared with the unmodified polybutylene adipate terephthalate / calcium carbonate material, effectively improving the mechanical properties of polybutylene adipate terephthalate.

[0030] (3) The leaf acid-4-aminomethyl benzoic acid-calcium carbonate of the present application can improve the compatibility between the polybutylene adipate terephthalate / calcium carbonate composite material, and the inorganic particles are more closely combined to produce a certain strength of interfacial adhesion, which weakens the force between the polymer chains, making the movement of the polymer chains easier, and the elongation at break increases from 584% to 698%, improving the mechanical properties of the composite material. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is the infrared spectrum of calcium carbonate, 4-aminomethyl benzoic acid-calcium carbonate, and leaf acid-4-aminomethyl benzoic acid-calcium carbonate proposed by the present application;

[0032] Figure 2 is the ionization equation of 4-aminomethyl benzoic acid.

[0033] Figure 3 is the esterification-coordination mechanism of the present application;

[0034] Figure 4 is the amidation mechanism of the present application;

[0035] Figure 5 is the hydrogen bonding mechanism of the present application. DETAILED DESCRIPTION

[0036] The present application is further illustrated in detail by the following examples.

[0037] Example 1

[0038] The preparation operation steps of the bifunctional modified calcium carbonate with capacity and reinforcement effects are as follows:

[0039] (1) Preparation of 4-aminomethyl benzoic acid-calcium carbonate (PAMBA-CaCO3)

[0040] (1.1) 15 g of 4-aminomethyl benzoic acid (PAMBA) was added to 100 mL of deionized water as a solvent, and stirred uniformly to prepare a 4-aminomethyl benzoic acid solution.

[0041] (1.2) Spraying onto the surface of 1 kg of pretreated calcium carbonate, mixing at a temperature of 70°C and a rotation speed of 1000 r / min for 30 min, and drying at a temperature of 80°C for 6 h to prepare the pretreated calcium carbonate (PAMBA-CaCO3).

[0042] (2) Preparation of folic acid-4-aminomethyl benzoic acid-calcium carbonate (FA-PAMBA-CaCO3)

[0043] (2.1) 20 g of folic acid (FA) was dissolved in 100 mL of dimethyl sulfoxide (DMSO) solvent at room temperature, and ultrasonic treatment was performed for 30 min until complete dissolution to obtain a folic acid solution.

[0044] (2.2) 5 mg of dicyclohexyl carbodiimide (DCC) and 5 mg of N-hydroxysuccinimide (NHS) were added for reaction, and magnetic stirring was performed at room temperature overnight (8 h), and the reaction by-products were removed by filtration to obtain an activated ester solution.

[0045] (2.3) The activated ester solution was slowly added to the 4-aminomethyl benzoic acid-calcium carbonate (PAMBA-CaCO3) in a high-speed mixer at a rotation speed of 200 r / min, and the reaction was performed for 8 h while stirring at a speed of 80 mL / h, and the product was obtained by mixing at room temperature, and folic acid-4-aminomethyl benzoic acid-calcium carbonate (FA-PAMBA-CaCO3) was prepared by drying at 80°C for 6 h.

[0046] (3) Preparation of the mixture

[0047] In a high-speed mixer, 1 kg of polybutylene adipate terephthalate (PBAT) and 200 g of folic acid-4-aminomethylbenzoic acid-calcium carbonate (FA-PAMBA-CaCO3) (mass ratio 5:100) were mixed at room temperature at a speed of 1000 r / min for 20 min to obtain a mixture.

[0048] (4) Preparation of the bifunctional modified calcium carbonate

[0049] The mixture was melt-extruded in a twin-screw extruder at a screw speed of 300 r / min, a feeding speed of 5 r / min, and an extrusion temperature zone of 130, 135, 140, 145, 150, 155, 160, 160, 160, 160, 150, 155°C to obtain a bifunctional modified calcium carbonate (PBAT / FA-PAMBA-CaCO3) composite material.

[0050] The bifunctional modified calcium carbonate prepared in Example 1 was heavy calcium powder with a particle size of 800 mesh, a tensile strength of 28.68 MPa, an elongation at break of 602%, and a contact angle of 89.00°.

[0051] Example 2

[0052] The preparation operation steps of the bifunctional modified calcium carbonate with both compatibilization and reinforcement effects are as follows:

[0053] (1) Preparation of 4-aminomethylbenzoic acid-calcium carbonate (PAMBA-CaCO3)

[0054] (1.1) 100 mL of deionized water was used as a solvent, 15 g of 4-aminomethylbenzoic acid (PAMBA) was added, and stirred uniformly to prepare a 4-aminomethylbenzoic acid solution.

[0055] (1.2) Sprayed onto the surface of 1 kg of pretreated calcium carbonate, mixed at a temperature of 70°C and a speed of 1000 r / min for 30 min to obtain a product, and dried at 80°C for 6 h to obtain the pretreated calcium carbonate PAMBA-CaCO3.

[0056] (2) Preparation of folic acid-4-aminomethylbenzoic acid (FA-PAMBA-CaCO3)

[0057] (2.1) 20 g of folic acid (FA) was weighed into 100 mL of dimethyl sulfoxide (DMSO) solvent, and ultrasonicated at room temperature for 30 min until completely dissolved to obtain a folic acid solution.

[0058] (2.2) Subsequently, 5 mg of dicyclohexyl carbodiimide (DCC) and 5 mg of N-hydroxysuccinimide (NHS) were added and reacted under magnetic stirring at room temperature overnight (8 h), and the reaction by-product was removed by filtration to obtain an activated ester solution.

[0059] (2.3) The activated ester solution was added dropwise into 4-aminomethylbenzoic acid-calcium carbonate (PAMBA-CaCO3) at a speed of 80 mL / h under stirring at a speed of 200 r / min in a high-speed mixer, and the reaction was performed for 8 h to obtain the product by mixing at room temperature and drying at 80 °C for 6 h to prepare folic acid-4-aminomethylbenzoic acid-calcium carbonate (FA-PAMBA-CaCO3).

[0060] (3) Preparation of the mixture

[0061] In a high-speed mixer, 1 kg of polybutylene adipate terephthalate (PBAT) and 250 g of folic acid-4-aminomethylbenzoic acid-calcium carbonate (FA-PAMBA-CaCO3) (mass ratio 5:100) were mixed at room temperature at a speed of 1000 r / min for 20 min to obtain the mixture;

[0062] (4) Preparation of the bifunctional modified calcium carbonate

[0063] The mixture was melt-extruded in a twin-screw extruder at a screw speed of 300 r / min, a feeding speed of 5 r / min, and an extrusion temperature zone of 130, 135, 140, 145, 150, 155, 160, 160, 160, 160, 150, 155 °C to obtain the bifunctional modified calcium carbonate (PBAT / FA-PAMBA-CaCO3) composite material.

[0064] The bifunctional modified calcium carbonate prepared in Example 2 was heavy calcium powder with a particle size of 800 mesh, a tensile strength of 30.36 MPa, an elongation at break of 698%, and a contact angle of 94.60°.

[0065] Example 3

[0066] The preparation operation steps of the bifunctional modified calcium carbonate with both compatibilization and reinforcement effects are as follows:

[0067] (1) Preparation of 4-aminomethylbenzoic acid-calcium carbonate (PAMBA-CaCO3)

[0068] (1.1) 100 mL of deionized water was used as a solvent, 15 g of 4-aminomethylbenzoic acid (PAMBA) was added and stirred uniformly to prepare a 4-aminomethylbenzoic acid solution.

[0069] (1.2) Spraying to the surface of 1 kg of pretreated calcium carbonate, mixing at 70°C temperature, 1000 r / min speed for 30 min to obtain the product, and drying at 80°C for 6 h to prepare the pretreated calcium carbonate PAMBA-CaCO3.

[0070] (2) Preparation of folic acid-4-aminomethylbenzoic acid (FA-PAMBA-CaCO3)

[0071] (2.1) 20 g of folic acid (FA) was weighed in 100 mL of dimethyl sulfoxide (DMSO) solvent, ultrasonic treatment at room temperature for 30 min until completely dissolved to obtain a folic acid solution.

[0072] (2.2) Then 5 mg of dicyclohexyl carbodiimide (DCC) and 5 mg of N-hydroxysuccinimide (NHS) were added and reacted, and the reaction was stirred magnetically at room temperature overnight (8 h), and the reaction by-product was removed by filtration to obtain an activated ester solution.

[0073] (2.3) In a high-speed mixer, the activated ester solution was added dropwise in 4-aminomethylbenzoic acid-calcium carbonate (PAMBA-CaCO3) at a speed of 80 mL / h under stirring at a speed of 200 r / min, and the reaction was carried out for 8 h, and the product was obtained by mixing at room temperature, and dried at 80°C for 6 h to prepare folic acid-4-aminomethylbenzoic acid-calcium carbonate (FA-PAMBA-CaCO3).

[0074] (3) Preparation of the mixture

[0075] In a high-speed mixer, 1 kg of polybutylene adipate terephthalate (PBAT) and 300 g of folic acid-4-aminomethylbenzoic acid-calcium carbonate (FA-PAMBA-CaCO3) (mass ratio 5:100) were mixed at room temperature at a speed of 1000 r / min for 20 min to prepare the mixture;

[0076] (4) Preparation of the bifunctional modified calcium carbonate

[0077] In a twin-screw extruder, the mixture was melt-extruded at a screw speed of 300 r / min, the feeding speed was set to 5 r / min, and the extrusion temperature zone was set to 130, 135, 140, 145, 150, 155, 160, 160, 160, 160, 150, 155°C to obtain the bifunctional modified calcium carbonate (PBAT / FA-PAMBA-CaCO3) composite material.

[0078] The bifunctional modified calcium carbonate prepared in Example 3 is heavy calcium powder with a particle size of 800 mesh; the tensile strength is 28.12 Mpa, the elongation at break is 620%, and the contact angle is 90.20°.

[0079] Comparative Example 1

[0080] Take 200 g of calcium carbonate and 1 kg of polybutylene adipate terephthalate into a high-speed mixer, mix at room temperature at 1000 r / min for 20 min, then melt and extrude the uniformly mixed raw materials through a twin-screw extruder, the screw speed is 300 r / min, the feeding speed is set to 5 r / min, and the extrusion temperature zone is set to 130, 135, 140, 145, 150, 155, 160, 160, 160, 160, 150, 155 ℃, to obtain polybutylene adipate terephthalate / calcium carbonate composite material.

[0081] Comparative Example 2

[0082] First, 15 g of 4-aminomethyl benzoic acid is weighed to prepare a 4-aminomethyl benzoic acid solution with 1 kg of calcium carbonate in a high-speed mixer, the high-speed mixer temperature is set to 70 ℃, the rotation speed is set to 1000 r / min, and high-speed mixing is carried out for 30 min to obtain 4-aminomethyl benzoic acid-calcium carbonate. Then, 200 g of 4-aminomethyl benzoic acid-calcium carbonate and 1 kg of polybutylene adipate terephthalate are placed in a high-speed mixer and mixed at room temperature at a rotation speed of 1000 r / min for 20 min. Finally, the uniformly mixed raw materials are melt-extruded through a twin-screw extruder, the screw speed is 300 r / min, the feeding speed is set to 5 r / min, and the extrusion temperature zone is set to 130, 135, 140, 145, 150, 155, 160, 160, 160, 160, 150, 155 ℃, to obtain polybutylene adipate terephthalate / 4-aminomethyl benzoic acid-calcium carbonate composite material.

[0083] Comparative Example 3

[0084] First, 20 g of folic acid is dissolved in 100 mL of dimethyl sulfoxide solvent, 5 mg of dicyclohexyl carbodiimide and 5 mg of N-hydroxysuccinimide are added, and the mixture is stirred at room temperature to obtain an active ester solution. In a high-speed mixer, the active ester solution is slowly added while stirring at a rotation speed of 200 r / min, and the reaction is carried out for 8 h. The product is mixed at room temperature and dried at 80 ℃ for 6 h to obtain folic acid-calcium carbonate. Then, 200 g of folic acid-calcium carbonate and 1 kg of polybutylene adipate terephthalate are placed in a high-speed mixer and mixed at room temperature at a rotation speed of 1000 r / min for 20 min. Finally, the uniformly mixed raw materials are melt-extruded through a twin-screw extruder, the screw speed is 300 r / min, the feeding speed is set to 5 r / min, and the extrusion temperature zone is set to 130, 135, 140, 145, 150, 155, 160, 160, 160, 160, 150, 155 ℃, to obtain polybutylene adipate terephthalate / folic acid-calcium carbonate composite material.

[0085] This invention performs infrared spectroscopy on calcium carbonate samples, 4-aminomethylbenzoic acid-calcium carbonate samples, and folic acid-4-aminomethylbenzoic acid-calcium carbonate samples, and the results are as follows: Figure 1 As shown. By Figure 1 It can be seen that at an infrared wavenumber of 711 cm⁻¹ -1 871cm -1 1795cm -1 2510cm -1 The absorption peaks appearing at 1538 cm⁻¹ are characteristic absorption peaks of calcium carbonate, representing the in-plane and out-of-plane bending vibrations and stretching vibrations of calcium carbonate ions, as well as the stretching vibration of the carbonyl group. From the infrared spectra of the 4-aminomethylbenzoic acid-calcium carbonate and folic acid-4-aminomethylbenzoic acid-calcium carbonate samples, the peak at 1538 cm⁻¹ is... -1 1431cm -1 The characteristic absorption peak at 1681 cm⁻¹ is likely due to the coupling effect of the carboxyl group formed by the chemical bonding between the carboxyl group and the calcium ion; the characteristic absorption peak at 1681 cm⁻¹ is observed in the infrared spectrum of the folic acid-4-aminomethylbenzoic acid-calcium carbonate sample. -1 The characteristic absorption peak appearing at [location] is the amide I band, due to the reaction between the amino and carboxyl groups to form amide bonds. The above infrared analysis confirms that 4-aminomethylbenzoic acid successfully modified calcium carbonate.

[0086] Table 1. Activation rate and contact angle test

[0087]

[0088]

[0089] This invention tested the activation rate and contact angle of calcium carbonate, 4-aminomethylbenzoic acid-calcium carbonate, and folic acid-4-aminomethylbenzoic acid-calcium carbonate samples. The results are shown in Table 1. Compared with calcium carbonate, the activation rate and contact angle of the 4-aminomethylbenzoic acid-calcium carbonate and folic acid-4-aminomethylbenzoic acid-calcium carbonate samples were increased. The folic acid-4-aminomethylbenzoic acid-calcium carbonate sample had the highest contact angle and activation rate, reaching 137.5° and 99.10%, respectively. With the modification of calcium carbonate, the hydrophobicity of the folic acid-4-aminomethylbenzoic acid-calcium carbonate sample increased, resulting in poor compatibility with water. The surface properties of the two samples became opposite, and the contact angle of the calcium carbonate sample gradually increased with modification.

[0090] Table 2 Contact Angle Test

[0091]

[0092] The polybutylene terephthalate sample, the polybutylene terephthalate / calcium carbonate sample, the polybutylene terephthalate / 4-aminomethyl benzoic acid-calcium carbonate sample and the polybutylene terephthalate / folic acid-4-aminomethyl benzoic acid-calcium carbonate sample are subjected to contact angle test, and the results are shown in Table 2. Compared with the pure polybutylene terephthalate, the contact angle of the polybutylene terephthalate / folic acid-4-aminomethyl benzoic acid-calcium carbonate sample is increased from 78.54° to 94.60°, and the folic acid-4-aminomethyl benzoic acid-calcium carbonate can effectively improve the compatibility between the two phases of the composite material.

[0093] Table 3 mechanical property test

[0094]

[0095]

[0096] The polybutylene terephthalate sample, the polybutylene terephthalate / calcium carbonate sample, the polybutylene terephthalate / 4-aminomethyl benzoic acid-calcium carbonate sample and the polybutylene terephthalate / folic acid-4-aminomethyl benzoic acid-calcium carbonate sample are subjected to mechanical property test, and the results are shown in Table 3. As shown in Table 3, the polybutylene terephthalate / folic acid-4-aminomethyl benzoic acid-calcium carbonate sample has the best tensile strength, which can reach 30.36Mpa at the maximum. When the polybutylene terephthalate is directly blended with calcium carbonate, the interfacial compatibility of the polybutylene terephthalate and calcium carbonate is poor, stress concentration and crack phenomenon occur in the film during the tensile process, and thus the mechanical properties, especially the toughness of the material, are greatly reduced. However, after the addition of folic acid-4-aminomethyl benzoic acid-calcium carbonate, the tensile strength of the material is significantly improved, and the reason is that the compatibility of the polybutylene terephthalate and calcium carbonate is improved, and the tensile strength is improved.

Claims

1. A method for preparing bifunctional modified calcium carbonate with both compatibilizing and strengthening effects, characterized in that, The operation steps are as follows: (1) Preparation of 4-aminomethylbenzoic acid-calcium carbonate (1.1) Add 4-aminomethylbenzoic acid to deionized water at a mass-to-volume ratio of 10g:100mL, stir until homogeneous, and obtain a 4-aminomethylbenzoic acid solution; (1.2) Spray 4-aminomethylbenzoic acid solution onto the surface of pretreated calcium carbonate at a mass ratio of (1.5-2):100, mix at high speed, and dry to obtain pretreated calcium carbonate; (2) Preparation of folic acid-4-aminomethylbenzoic acid-calcium carbonate (2.1) Add folic acid (FA) to dimethyl sulfoxide solvent at a mass ratio of (5-10):100, and sonicate until completely dissolved to obtain folic acid solution; (2.2) Add dicyclohexylcarbodiimide and N-hydroxysuccinimide to folic acid solution at a mass ratio of (0.01-0.02):100, stir magnetically at room temperature, filter to remove reaction byproducts, and obtain active ester solution. (2.3) In a high-speed mixer, while stirring, an active ester solution was added dropwise to 4-aminomethylbenzoic acid-calcium carbonate at a dropping rate of 80-100 mL / h. The reactants were dried at 80 °C for 6 h to obtain folic acid-4-aminomethylbenzoic acid-calcium carbonate. (3) Preparation of mixture The polybutylene terephthalate and the folic acid-4-aminomethylbenzoic acid-calcium carbonate were mixed at high speed according to a mass ratio of (5-10):100 to obtain a mixture. (4) Preparation of bifunctional modified calcium carbonate In a twin-screw extruder, the mixture is melt-extruded to obtain bifunctional modified calcium carbonate; The bifunctional modified calcium carbonate is heavy calcium carbonate powder with a particle size of 800-1000 mesh; tensile strength of 28.68 MPa to 30.36 MPa; elongation at break of 602% to 698%; and contact angle of 89.00° to 94.60°.

2. The preparation method according to claim 1, characterized in that: In step (1.2), the high-speed mixing conditions are: temperature 70℃, rotation speed 1000rpm / min, and mixing time 30min.

3. The preparation method according to claim 1, characterized in that: In step (2.1), the ultrasound conditions are: at room temperature, ultrasound for 30 minutes.

4. The preparation method according to claim 1, characterized in that: In step (2.2), the reaction is carried out at room temperature with magnetic stirring for 8-10 hours.

5. The preparation method according to claim 1, characterized in that: In step (2.3), the high-speed mixing conditions are: room temperature, 1000 rpm / min, and 8 h of mixing reaction.

6. The preparation method according to claim 1, characterized in that: In step (2.3), the dropping conditions are: dropping rate 80-100 mL / h and reaction time 6-8 h.

7. The preparation method according to claim 1, characterized in that: In step (3), the high-speed mixing conditions are: temperature 45-65℃ and time 1-3h.

8. The preparation method according to claim 1, characterized in that: In step (4), the melt extrusion conditions are: screw speed is 200-300 rpm, feeding speed is 5-7 Hz, and extrusion temperature range is set to 160, 165, 170, 175, 180, 185, 190, 190, 190, 185, 180℃.

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