A PBAT / PGA / talcum powder composite material and preparation method thereof

Abstract

The present invention adopts a preparation method of a PBAT / PGA / talc (TALC) composite material, comprising the following steps: weighing 65 parts of PBAT and 35 parts of PGA and placing them in a torque rheometer mixing chamber, and premixing them at 235° C. to obtain a PBAT / PGA 65 / 35 blend; and blending the PBAT / PGA 65 / 35 blend again in the mixing chamber, adding 0.8 parts of a multi-epoxy chain extender and 10-20 parts of talc at 170° C. to perform melt blending to obtain a two-step composite material. The method first adds PGA organic resin under high temperature conditions (235°C) for melt blending to obtain a simple binary blend; then adds talcum powder inorganic particles under relatively low temperature blending conditions (170°C) to prepare a PBAT matrix that is completely melted, a PGA dispersed phase that maintains a solid particle state, and talcum powder inorganic particles under the volume expansion of a multi-epoxy chain extender ADR to obtain a PBAT / PGA / TALC composite material with relatively balanced material strength, modulus and tensile toughness, especially a significantly enhanced tensile modulus.

Description

Technical Field

[0001] The present invention relates to the field of polymer materials, and in particular to a PBAT / PGA / talcum powder composite material and a preparation method thereof. Background Art

[0002] Among the many biodegradable plastic resins, polybutylene adipate / terephthalate (PBAT) has good ductility, elongation at break, heat resistance and impact resistance, and excellent biodegradability, and has high application potential in the fields of environmentally friendly disposable shopping bags, packaging films, and ground films. However, due to its shortcomings such as low tensile modulus and tensile yield strength, the performance and application scope of the above-mentioned PBAT products are greatly limited. In response to the above problems, researchers often improve the tensile modulus and tensile yield strength of PBAT materials by mixing rigid inorganic fillers or rigid polymer resins into the PBAT matrix. Among biodegradable polymer resins, PLA is often used as a reinforcing component to reinforce modified PBAT materials due to its high stiffness and strength.

[0003] Polyglycolic acid (PGA) is the simplest linear aliphatic polyester with excellent biodegradability, heat resistance, biocompatibility, barrier properties and mechanical properties. It has great application potential in biomedicine, oil and gas extraction and packaging. Since polyglycolic acid (PGA) has the advantages of higher crystallinity, excellent mechanical strength, high gas barrier properties and heat resistance, blending PGA with PBAT is expected to improve the strength, modulus and barrier properties of PBAT materials, and further improve the performance and application fields of PBAT materials. However, for PBAT / PGA blends, the PGA content should generally not exceed 40wt%. Excessive PGA content will cause the PGA dispersed phase to transform into a continuous phase, causing the blend to lose the flexibility of the PBAT matrix. Therefore, it is impossible to achieve the purpose of obtaining a PBAT modified material with higher tensile yield strength and modulus by simply increasing the PGA content. As a common inorganic reinforcing material, ultrafine talc (TALC) filler has the advantages of large specific surface area, good reinforcing effect and relatively low price. However, at higher filling amounts, the mechanical modification effect of highly filled talc-modified polymers is often greatly limited because the agglomeration problem between talc particles during the dispersion process is difficult to solve effectively.

[0004] Therefore, it is necessary to develop a technical method for synergistically enhancing and modifying PBAT by compounding polyglycolic acid (PGA) and talc (TALC). Summary of the invention

[0005] In view of this, the present invention provides a method for preparing a PBAT / PGA / talcum powder composite material to solve the problem that the blended composite material prepared by the existing method has poor balance in tensile yield strength, modulus and elongation at break.

[0006] In one aspect, the present invention adopts a method for preparing a PBAT / PGA / talcum powder composite material, comprising the following steps:

[0007] S1: First step: 65 parts of PBAT and 35 parts of PGA were weighed and placed in the mixing chamber of the torque rheometer, and premixed at 235°C to obtain a 65 / 35 PBAT / PGA blend;

[0008] S2 second step blending: The PBAT / PGA 65 / 35 blend is then put back into the mixing chamber, and 0.8 parts of a multi-epoxy chain extender and 10-20 parts of talc are added at 170°C for melt blending to obtain a two-step composite material.

[0009] Preferably, the amount of talc is 10 parts.

[0010] Preferably, in step S1, the blending speed and blending time are 50 rpm and 8 min, respectively.

[0011] Preferably, in step S2, the blending speed and blending time are 50 rpm and 8 min, respectively.

[0012] On the other hand, the present invention also provides a synergistically reinforced modified PBAT / PGA / talc composite material prepared by a two-step blending method.

[0013] The present invention creatively provides a method for preparing a composite polymer material by two-step melt blending at different temperature stages, that is, in the first step, a simple binary blend of PBAT / PGA is prepared under high-temperature melt blending conditions (235° C.); then, in the second step, a lower temperature blending condition (170° C.), the PBAT matrix is ​​melted, while the PGA dispersed phase remains in a solid particle state, a multi-epoxy chain extender ADR is added as a PBAT / PGA interface reaction compatibilizer, and a certain ratio of TALC inorganic particles are added, and finally a compatibilized PBAT / PGA / TALC composite material is prepared. The tensile yield strength, tensile modulus and elongation at break of the prepared PBAT / PGA / talc composite material are 11.23 MPa, 197.92 MPa and 214.4% respectively. The PBAT / PGA / talc composite material of the present invention has a higher elongation at break and a more significant reinforcing effect, especially a significant improvement in the tensile modulus, which can better meet the actual performance requirements of the material. DETAILED DESCRIPTION

[0014] The main raw materials involved in the following examples are:

[0015] Polybutylene adipate / terephthalate (PBAT): C1200, BASF, Germany, melt mass flow rate: 29.6 g / 10 min (235 ° C, 2.16 kg);

[0016] Polyglycolic acid (PGA): Inner Mongolia Pujing Polymer Material Technology Co., Ltd., China, melt mass flow rate: 22.9 g / 10 min (235 ° C, 2.16 kg);

[0017] Polyvalent epoxy chain extender (ADR): ADR 4468, BASF, Germany.

[0018] The instruments and equipment used in the following examples mainly include:

[0019] Torque rheometer: Model XSS-300, Shanghai Kechuang Rubber & Plastic Machinery Equipment Co., Ltd.

[0020] Molding machine: CH-0206, Dongguan Chuanghong Instrument Equipment Co., Ltd.

[0021] Melt flow rate (MFR) tester: XNR-400B, Chengde Desheng Testing Equipment Co., Ltd.

[0022] Electronic tensile testing machine: Model WDW-1, Jinan Yinuo Century Experimental Instrument Co., Ltd.

[0023] Embodiment 1: A method for preparing a PBAT / PGA / talc composite material, comprising the following steps:

[0024] S1. Blending: 65 parts of PBAT and 35 parts of PGA were weighed according to weight and placed in the mixing chamber of the torque rheometer for premixing for 8 minutes. The blending temperature and speed were 235°C and 50 rpm, respectively, to obtain a PBAT / PGA 65 / 35 blend;

[0025] S2 second step blending: The PBAT / PGA blend was then put back into the mixing chamber, and 0.8 parts of ADR and 10 parts of TALC were added at 170°C for melt blending. The blending speed and blending time were 50 rpm and 8 min, respectively, to finally obtain a (PBAT / PGA) / TALC / ADR 65 / 35 / 10 / 0.8 two-step composite material.

[0026] Embodiment 2: The difference between Embodiment 2 and Embodiment 1 is that the weight fraction of TALC is 15 parts.

[0027] Example 3: The difference between Example 3 and Example 1 is that the weight fraction of TALC is 20 parts.

[0028] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 adopts a one-step method to prepare a PBAT / PGA / TALC / ADR material, specifically: 65 parts of PBAT, 35 parts of PGA, 10 parts of TALC and 0.8 parts of ADR are weighed and put into the mixing chamber of the torque rheometer at the same time, and blended at 235 ° C at a speed of 50 rpm for 8 min to obtain a blend, which is recorded as a PBAT / PGA / TALC / ADR 65 / 35 / 10 / 0.8 one-step composite material.

[0029] Comparative Example 2: The difference between Comparative Example 2 and Comparative Example 1 is that the weight fraction of TALC is 15 parts.

[0030] Comparative Example 3: The difference between Comparative Example 2 and Comparative Example 1 is that the weight fraction of TALC is 20 parts.

[0031] Comparative Example 4: The difference between Comparative Example 4 and Comparative Example 1 is that 65 parts of PBAT and 35 parts of PGA are weighed and put into the mixing chamber of the torque rheometer at the same time, and PBAT / PGA 65 / 35 is obtained after blending at 235° C. at a speed of 50 rpm for 8 minutes.

[0032] The blended materials prepared in the above embodiments and comparative examples of the present invention were tested and characterized, and the results are as follows:

[0033] (1) The melt mass flow rate (MFR) test was performed on the blended composite materials prepared in Examples 1 to 3 and Comparative Examples 1 to 3. As shown in the results in Table 1, under the test condition of 170°C, the MFR of the PBAT / PGA / TALC / ADR 65 / 35 / 10 / 0.8 one-step composite material was only 1.4 g / 10 min. The lower the MFR value, the greater the melt viscosity. The MFR of the (PBAT / PGA) / TALC / ADR 65 / 35 / 10 / 0.8 composite material prepared by the two-step method was 9.0 g / 10 min. When the TALC addition amount was 15 and 20 parts, the MFR of the two-step composite material decreased to 6.8 and 6.4 g / 10 min, respectively. It shows that compared with the one-step composite material with the same ratio, the composite material prepared by the two-step method has a larger MFR value and higher melt fluidity.

[0034] Table 1 Melt mass flow rate (MFR) of composite materials

[0035]

[0036] (2) The tensile properties of the blended composite materials prepared in Examples 1 to 3 and Comparative Examples 1 to 4 were tested. As shown in Table 2, the elongation at break of pure PBAT is as high as 1112.3%, but the tensile yield strength and tensile modulus are low, only 7.66MPa and 57.99MPa. After adding PGA, the tensile yield strength and tensile modulus of the PGA / PBAT 65 / 35 binary blend are increased to 11.71MPa and 127.44MPa, respectively, and the strengthening effect is obvious. However, due to the poor compatibility of the PBAT / PGA interface, the elongation at break is reduced to 157.0%. With the addition of 0.8 parts of ADR and 10 parts of TALC, the tensile yield strength, tensile modulus and elongation at break of the PBAT / PGA / TALC / ADR 65 / 35 / 10 / 0.8 one-step composite material reached 11.11MPa, 137.39MPa and 315.0%, respectively. When the TALC addition amount was further increased to 15 parts and 20 parts, the tensile modulus of the one-step composite material increased to 155.39MPa and 182.23MPa, respectively, but the elongation at break decreased to 260.5% and 228.0%, respectively. This is because when TALC is more, the rigidity of the composite material continues to increase, but it will affect the improvement of its elongation at break.

[0037] In the composite material prepared by the two-step method, the synergistic reinforcement effect of TALC and PGA is more significant. When the TALC addition amount is 10 parts, the tensile yield strength, tensile modulus and elongation at break of the (PBAT / PGA) / TALC / ADR 65 / 35 / 10 / 0.8 two-step composite material reach 11.23MPa, 197.92MPa and 214.4% respectively; when the TALC addition amount is 15 parts, its tensile yield strength and tensile modulus further increase to 13.69MPa and 255.73MPa, while its elongation at break decreases to 137.9%. When the TALC addition amount increases to 20 parts, its tensile yield strength, tensile modulus and elongation at break all decrease. This shows that compared with the existing one-step method, the synergistic reinforcement effect of TALC and PGA on the PBAT matrix in the composite material prepared by the two-step method is more significant.

[0038] Table 2 Tensile properties of composite materials

[0039]

[0040] In summary, when the two-step blending method of the present invention is used to prepare the (PBAT / PGA) / TALC / ADR composite material, the first step of blending is to melt blend PBAT and PGA at 235°C to prepare a PBAT / PGA blend. At this time, due to the lack of the compatibilizer ADR, the poor compatibility between the PBAT matrix and the PGA component makes the PGA dispersed phase size in the binary blend larger; then in the second step of blending, 0.8 parts of ADR and different parts of TALC are added at 170°C for blending, and finally a (PBAT / PGA) / TALC / ADR two-step composite material is obtained. Since the second step blending is carried out at a lower temperature of 170°C, the PBAT matrix is ​​completely melted at this time, but the PGA dispersed phase is not melted, so that the ADR molecules can only be distributed in large quantities in the PBAT matrix and in small quantities on the PBAT / PGA liquid / solid interface, but cannot enter the PGA dispersed phase. The multi-epoxy groups on the ADR can simultaneously react with the end carboxyl groups / or end hydroxyl groups of the PGA macromolecules exposed on the surface of the PGA dispersed particles and the end carboxyl groups / or end hydroxyl groups on the PBAT melt macromolecules to open the ring, so that ADR and PBAT macromolecules are grafted on the surface of the PGA particles, thereby increasing the PBAT / PGA interface compatibility and adhesion. However, since the PGA dispersed phase remains in a solid particle state in the second step blending system, although the PBAT / PGA interface compatibility is improved and the interfacial tension is reduced, its dispersed phase size is not reduced, but the larger dispersed phase size during the first step of high temperature blending is maintained. Therefore, compared with the one-step composite material with the same ratio, the composite material prepared by the two-step blending method has a better synergistic reinforcement effect of two-component rigid particles.

[0041] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a PBAT / PGA / talcum powder composite material, characterized in that: The following steps are involved: S1: First step: 65 parts of PBAT and 35 parts of PGA were weighed and placed in the mixing chamber of the torque rheometer, and premixed at 235°C to obtain a 65 / 35 PBAT / PGA blend; S2 second step blending: The PBAT / PGA 65 / 35 blend was then put back into the mixing chamber, and 0.8 parts of a multi-epoxy chain extender and 15 parts of talc were added at 170°C for melt blending to obtain a two-step composite material.

2. The method for preparing a PBAT / PGA / talc composite material according to claim 1, characterized in that: In step S1, the blending speed and blending time are 50 rpm and 8 min, respectively.

3. The method for preparing a PBAT / PGA / talc composite material according to claim 1, characterized in that: In step S2, the blending speed and blending time are 50 rpm and 8 min, respectively.

4. A PBAT / PGA / talc composite material prepared according to the method according to any one of claims 1 to 3.

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