Modified PBAT material with high puncture and long edge cutting timeliness and preparation method thereof

Abstract

The modified PBAT material is prepared from the following components: PBAT resin, PLA resin, modified mineral powder, modified activated carbon powder, an antioxidant, a lubricant and the like. Wherein the modified activated carbon powder is alkaline activated carbon powder activated by strong alkali, and the modified mineral powder is silane coupling agent coated and modified flaky mineral powder with large diameter-thickness ratio. The large-diameter-thickness-ratio sheet-shaped modified mineral powder activated by the silane coupling agent and PBAT matrix resin are subjected to interface grafting reaction, insufficient crystallization caused by molecular chain movement of the PBAT matrix resin is limited, on the other hand, the large-diameter-thickness-ratio sheet-shaped mineral powder is arranged in the direction of a barrel film in an oriented mode, and the puncture resistance of the film is remarkably improved. Meanwhile, the alkaline activated activated carbon can adsorb acid small molecules in the material, inhibit the promotion effect of small molecules in a material system on material crystallization and hydrolysis and delay edge cutting bonding performance attenuation, the method is suitable for preparing the biodegradable edge sealing bag, and the time-delay edge sealing strength of the prepared biodegradable edge sealing bag can reach 80% or above of the initial edge sealing strength.

Description

Technical Field

[0001] The present invention belongs to the field of biodegradable plastics, and in particular relates to a modified PBAT material with high puncture resistance and long edge shear timeliness and a preparation method thereof. Background Art

[0002] Side-seal bags have more beautiful side seals than traditional heat-sealed edges, high bag-making efficiency, and less scrap. They are widely used in packaging in many fields such as clothing, tea beverages, express logistics, etc. Biodegradable materials are used in side-seal bags, which are not only biodegradable but also have excellent side-seal performance. However, the conventional process in the existing side-seal bag field is to blow the film into rolls, store them in a warehouse, and then cut the bags after about a week. These biodegradable materials often have the problem of brittle side seals when they are naturally left for a period of time after blowing the film and then cut into bags. This is called delayed side seal failure, which seriously affects the use and promotion of the material and the products prepared.

[0003] CN105416797A discloses a method for preparing degradable express bags using PLA, PBAT or PBS as raw materials. This invention mainly focuses on the research of the preparation process, and the thickener EAA ethylene-acrylic acid copolymer added therein is a non-degradable material, which is still prone to residual microplastics and cannot solve the problem of environmental pollution. At the same time, this technical solution does not explore whether the product has delayed edge seal failure. CN110091564A discloses a side-sealed bag material and its preparation method. This technical solution uses a three-layer blown film method and a composite structure with PLA as the outer layer and PBAT as the inner layer to achieve ideal performance. However, the inner and outer layers of the composite structure are connected by a polyurethane adhesive, which is not a biodegradable material. At the same time, this solution also does not provide a solution to the delayed edge seal failure phenomenon of the product. CN115403902A discloses a biodegradable material and a preparation method thereof. By combining polylactic acid and flexible biodegradable polyester, the problem of delayed edge seal failure in edge-sealed bag products is solved. However, the flexible biodegradable polyester can easily deform when subjected to stress, resulting in low puncture performance of the material, causing the puncture performance to be unqualified and unsatisfactory. Summary of the Invention

[0004] The purpose of the present invention is to provide a modified PBAT material with high puncture resistance and long edge-cutting timeliness, and a method for preparing the same. This invention utilizes an interfacial grafting reaction between activated modified, high-diameter-to-thickness flaky mineral powder and a PBAT matrix resin to limit the crystallization of the PBAT matrix resin. Furthermore, the high-diameter-to-thickness flaky mineral powder is oriented along the film direction, significantly improving the film's puncture resistance. Furthermore, alkaline-activated activated carbon can adsorb acidic small molecules in the material, inhibiting the effects of these small molecules on crystallization and hydrolysis, and slowing the degradation of edge-cutting adhesion properties. This material is suitable for preparing biodegradable edge-sealed bags. This product effectively addresses the delayed edge-seal failure phenomenon seen in existing edge-seal bags, achieving a delayed edge-seal strength exceeding 80% of the initial edge-seal strength.

[0005] To achieve the above object, the technical solutions adopted by the present invention are as follows:

[0006] A modified PBAT material with high puncture resistance and long edge shear time, the modified material comprising the following components in parts by weight:

[0007] 60-90 parts of PBAT resin, preferably 70-85 parts;

[0008] 3-12 parts of PLA resin, preferably 5-9 parts;

[0009] 5-20 parts of modified mineral powder, preferably 7-15 parts;

[0010] 2-8 parts, preferably 3-6 parts, of modified activated carbon powder;

[0011] 0.2-0.6 parts of antioxidant, preferably 0.3-0.5 parts;

[0012] Lubricant 0.2-0.6 parts, preferably 0.3-0.5 parts.

[0013] The modified activated carbon powder is alkaline activated carbon powder treated with strong alkali, and the modified mineral powder is a flaky mineral powder with a large diameter-to-thickness ratio treated with a silane coupling agent.

[0014] The melt index of the PBAT resin is 3-25 g / 10 min (190° C., 2.16 kg); the melt index of the PLA resin is 3-30 g / 10 min (190° C., 2.16 kg).

[0015] The modified activated carbon powder is an alkaline activated carbon powder activated by a strong alkali, and is prepared by: activating the activated carbon powder under strong alkali conditions, followed by filtering, washing, and drying to obtain the activated activated carbon powder; the strong alkali is, for example, potassium hydroxide or sodium hydroxide, wherein the concentration of the strong alkali aqueous solution is 45-50%; and the ratio of the activated carbon powder mass to the strong alkali aqueous solution volume (kg:L) is 1:1-1:3;

[0016] The activated carbon powder is fruit shell, wood, or coal-based activated carbon powder. Preferably, the activated carbon powder has a particle size D97 less than or equal to 28 μm, preferably a particle size D97 less than or equal to 20 μm, and a specific surface area ≥400 m 2 / g.

[0017] The modified mineral powder is a modified flaky mineral powder with a large diameter-to-thickness ratio treated with a silane coupling agent, wherein the flaky mineral powder is one or a combination of kaolin, talc, and mica, and the diameter-to-thickness ratio of the flaky mineral powder is ≥25;

[0018] The modified mineral powder is prepared by adding a silane coupling agent (such as KH570, KH560, KH550, etc.) to the dried mineral powder, stirring evenly to fully coat the mineral powder, and then heating and drying the mineral powder to obtain the modified mineral powder, wherein the mass ratio of the silane coupling agent to the mineral powder is 1:10-1:25.

[0019] The antioxidant is one or more of antioxidant 1010, antioxidant 168, antioxidant 264, antioxidant 1076, antioxidant B215, and antioxidant B225.

[0020] The lubricant is one or more of erucamide, zinc stearate, stearic acid monoglyceride, and ethylene bis stearamide.

[0021] The preparation method of the modified PBAT material with high puncture resistance and long edge shear time comprises the following steps:

[0022] PBAT resin, PLA resin, modified mineral powder, modified activated carbon powder, antioxidant, and lubricant are mixed in a high-speed mixer and then added to a twin-screw extruder for shear mixing and plasticization. Finally, extrusion pelletization produces a modified PBAT material with high puncture resistance and long edge shear resistance. The twin-screw extruder has an aspect ratio of at least 48:1, a screw speed of 300-600 rpm, and an extrusion temperature of 150°C-180°C.

[0023] Compared with the prior art, the present invention has the following technical advantages:

[0024] 1) The present invention restricts the crystallization of the PBAT matrix resin by grafting the activated modified large-diameter-thickness flaky mineral powder with the PBAT matrix resin interface. On the other hand, the large-diameter-thickness flaky mineral powder is oriented along the film direction during the film blowing process. The transversely arranged flaky mineral powder structure significantly improves the film's puncture resistance by more than 2.5N.

[0025] 2) Alkaline activated carbon can adsorb acidic small molecules in the material, inhibit the promotion of small molecules in the material system on material crystallization and aging hydrolysis, delay the attenuation of edge-cut adhesion performance, and is suitable for the preparation of biodegradable side-sealed bags. At the same time, this product effectively solves the delayed side-seal failure phenomenon of existing side-seal bag products. The delayed side-seal strength of the prepared biodegradable side-seal bag can reach more than 80% of the initial side-seal strength. DETAILED DESCRIPTION

[0026] The present invention will be further described below through specific examples. The examples of the present invention are only for illustration of the present invention and do not limit the scope of the present invention.

[0027] In each embodiment and comparative example, the main raw materials are from the following sources:

[0028]

[0029] Unless otherwise specified, other raw materials and reagents were purchased from commercial sources.

[0030] In each embodiment and comparative example, the performance test parameters and corresponding test methods of the PBAT modified material are as follows:

[0031] Test content unit Test Method Melt index g / 10min GB / T 3682 tensile strength MPa GB / T 1040-2006 Tensile modulus MPa GB / T 1040-2006 Elongation at break ％ GB / T 1040-2006 Instant edge shear strength T0 N QB / T2358 Place for 7 days and the cutting strength is T7 N QB / T2358 Puncture strength N GB / T 21302-2007

[0032] The processing equipment used is:

[0033] Twin-screw extruder, Carousel Maffei, model 26Mc 18, with an aspect ratio of 52 and a screw diameter of 26 cm;

[0034] Film blowing machine, Zhangjiagang Lianjiang Machinery Co., Ltd., model SCM 25, with an aspect ratio of 30 and a screw diameter of 25 cm.

[0035] The test equipment used is:

[0036] German Gottfert melt indexer, test conditions: 190℃, 2.16kg;

[0037] German ZWICK universal material testing machine, tensile test condition is 500mm / min;

[0038] German ZWICK universal material testing machine, edge shear strength test condition is 300mm / min.

[0039] Example 1

[0040] (1) Activated carbon (1.8 kg coconut shell activated carbon powder, 960 m 2 / g) was treated with 3 L of a 48% by mass aqueous solution of potassium hydroxide under reflux for 8 hours, filtered and thoroughly washed with hot distilled water until the pH value of the washing water was neutral, and the activated carbon was vacuum dried at 60° C. for 24 hours to obtain activated modified activated carbon powder.

[0041] (2) Preheat the mineral powder (4.8 kg, talc powder T84) to 100°C-110°C in a high-speed mixer, stir and dry, then evenly add 0.2 kg of the measured silane coupling agent (KH560) and stir for 10 minutes to obtain modified talc powder;

[0042] (3) 2 kg of modified activated carbon powder, 5 kg of modified mineral powder, 90 kg of PBAT resin, 3 kg of PLA resin, 0.2 kg of antioxidant 1010, and 0.6 kg of lubricant were added to a MIXER mixer and stirred at a stirring speed of 600 rpm / min for 4 minutes to mix evenly. The mixture was then added to a twin-screw extruder through the main feeding method. After water cooling, pelletizing, and drying, a modified PBAT material with high puncture resistance and long edge cutting time was obtained. The specific formula composition can be referred to Table 3. The twin-screw extruder speed was 300 rpm and the extrusion temperature was 150°C. Film blowing mechanical tests and edge cutting performance test evaluation were carried out, and the results are shown in Table 4.

[0043] Example 2

[0044] (1) Activated carbon (2.7 kg coconut shell activated carbon powder, 960 m 2 / g) was treated with 4.5 L of a 48% by mass aqueous solution of potassium hydroxide under reflux for 8 hours, filtered and thoroughly washed with hot distilled water until the pH value of the washing water was neutral, and the activated carbon was vacuum dried at 60° C. for 24 hours to obtain activated carbon powder;

[0045] (2) Preheat the mineral powder (6.6 kg, talc powder T84) to 100°C-110°C in a high-speed mixer, stir and dry, then evenly add 0.4 kg of the measured silane coupling agent (KH550) and stir for 10 minutes to obtain modified talc powder;

[0046] (3) 3 kg of modified activated carbon powder, 7 kg of modified mineral powder, 85 kg of PBAT resin, 5 kg of PLA resin, 0.3 kg of antioxidant 1010, and 0.5 kg of lubricant were added to a MIXER mixer and stirred at a stirring speed of 600 rpm / min for 4 minutes to mix evenly. The mixture was then added to a twin-screw extruder through the main feeding method. After water cooling, pelletizing, and drying, a modified PBAT material with high puncture resistance and long edge cutting time was obtained. The specific formula composition can be referred to Table 3. The twin-screw extruder speed was 350 rpm and the extrusion temperature was 160°C. Film blowing mechanical tests and edge cutting performance test evaluation were carried out, and the results are shown in Table 4.

[0047] Example 3

[0048] (1) Activated carbon (3.6 kg wood activated carbon powder, 580 m 2 / g) treated with 6L of 48% sodium hydroxide aqueous solution under reflux for 8 hours, filtered and thoroughly washed with hot distilled water until the pH value of the washing water was neutral, and the activated carbon was vacuum dried at 60°C for 24 hours to obtain activated carbon powder;

[0049] (2) Preheat the mineral powder (9.2 kg, mica HC400) to 100°C-110°C in a high-speed mixer, stir and dry, then evenly add 0.8 kg of the measured silane coupling agent (KH-560) and stir for 10 minutes to obtain modified talc powder;

[0050] (3) 4 kg of modified activated carbon powder, 10 kg of modified mineral powder, 79 kg of PBAT resin, 7 kg of PLA resin, 0.4 kg of antioxidant 1076, and 0.4 kg of lubricant were added to a MIXER mixer and stirred at a stirring speed of 600 rpm / min for 4 minutes to mix evenly. The mixture was then added to a twin-screw extruder through the main feeding method. After water cooling, pelletizing, and drying, a modified PBAT material with high puncture resistance and long edge cutting time was obtained. The specific formula composition can be referred to Table 3. The twin-screw extruder speed was 400 rpm and the extrusion temperature was 160°C. Film blowing mechanical tests and edge cutting performance test evaluation were carried out, and the results are shown in Table 4.

[0051] Example 4

[0052] (1) Activated carbon (5.4 kg coconut shell activated carbon powder, 960 m 2 / g) was treated with 8 L of a 48% by mass aqueous solution of potassium hydroxide under reflux for 8 hours, filtered and thoroughly washed with hot distilled water until the pH value of the washing water was neutral, and the activated carbon was vacuum dried at 60° C. for 24 hours to obtain activated carbon powder;

[0053] (2) Preheat the mineral powder (14 kg, talc powder T84) to 100°C-110°C in a high-speed mixer, stir and dry, then evenly add 1 kg of the measured silane coupling agent (KH-570) and stir for 10 minutes to obtain modified talc powder;

[0054] (2) 6 kg of modified activated carbon powder, 15 kg of modified mineral powder, 70 kg of PBAT resin, 9 kg of PLA resin, 0.5 kg of antioxidant 1010, and 0.3 kg of lubricant were added to a MIXER mixer and stirred at a stirring speed of 600 rpm / min for 4 minutes to mix evenly. The mixture was then added to a twin-screw extruder through the main feeding method. After water cooling, pelletizing, and drying, a modified PBAT material with high puncture resistance and long edge cutting time was obtained. The specific formula composition can be referred to Table 3. The twin-screw extruder speed was 500 rpm and the extrusion temperature was 170°C. Film blowing mechanical tests and edge cutting performance test evaluation were carried out, and the results are shown in Table 4.

[0055] Example 5

[0056] (1) Activated carbon (7.2 kg coconut shell activated carbon powder, 960 m 2 / g) treated with 10L of a 48% by mass aqueous solution of potassium hydroxide under reflux for 8 hours, filtered and thoroughly washed with hot distilled water until the pH value of the washing water was neutral, and the activated carbon was vacuum dried at 60°C for 24 hours to obtain activated carbon powder;

[0057] (2) Preheat the mineral powder (18.8 kg, talc powder T84) to 100°C-110°C in a high-speed mixer, stir and dry, then evenly add 1.2 kg of the measured silane coupling agent (KH-560) and stir for 10 minutes to obtain modified talc powder;

[0058] (3) 8 kg of activated modified carbon powder, 20 kg of modified mineral powder, 60 kg of PBAT resin, 12 kg of PLA resin, 0.6 kg of antioxidant 1010, and 0.2 kg of lubricant were added to a MIXER mixer and stirred at a stirring speed of 600 rpm / min for 4 minutes to mix evenly. The mixture was then added to a twin-screw extruder through the main feeding method. After water cooling, pelletizing, and drying, a modified PBAT material with high puncture resistance and long edge cutting time was obtained. The specific formula composition can be referred to Table 3. The twin-screw extruder speed was 600 rpm and the extrusion temperature was 180°C. Film blowing mechanical tests and edge cutting performance test evaluation were carried out, and the results are shown in Table 4.

[0059] Comparative Example 1

[0060] (2) 2.0 kg activated carbon powder (coconut shell activated carbon powder, 960 m 2100g), 5kg of mineral powder (talc T84), 90kg of PBAT resin, 3kg of PLA resin, 0.2kg of antioxidant 1010, and 0.6kg of lubricant were added to a MIXER blender and stirred at 600 rpm / min for 4 minutes until uniformly mixed. The material was then fed into a twin-screw extruder via a main feed method. After water cooling, pelletizing, and drying, a modified PBAT material with high puncture resistance and long edge shear strength was obtained. The specific formulation composition can be found in Table 3. The twin-screw extruder speed was 300 rpm and the extrusion temperature was 150°C. Film blowing mechanical tests and edge shear performance tests were conducted, and the results are shown in Table 4.

[0061] Comparative Example 2

[0062] (1) Activated carbon (1.8 kg coconut shell activated carbon powder, 960 m 2 / g) was treated with 3 L of a 48% by mass aqueous solution of potassium hydroxide under reflux for 8 hours, filtered and thoroughly washed with hot distilled water until the pH value of the washing water was neutral, and the activated carbon was vacuum dried at 60° C. for 24 hours to obtain activated modified activated carbon powder.

[0063] (2) 2 kg modified activated carbon powder, 5 kg mineral powder (talc T84), 90 kg PBAT resin, 3 kg PLA resin, 0.2 kg antioxidant 1010, and 0.6 kg lubricant were added to a MIXER mixer and stirred at a stirring speed of 600 rpm / min for 4 minutes to mix evenly. The mixture was then added to a twin-screw extruder through the main feeding method. After water cooling, pelletizing, and drying, a modified PBAT material with high puncture resistance and long edge cutting time was obtained. The specific formula composition can be referred to Table 3. The twin-screw extruder speed was 300 rpm and the extrusion temperature was 150°C. Film blowing mechanical tests and edge cutting performance test evaluations were carried out, and the results are shown in Table 4.

[0064] Comparative Example 3

[0065] (1) Preheat the mineral powder (4.8 kg, talc powder T84) to 100°C-110°C in a high-speed mixer, stir and dry, then evenly add 0.2 kg of the measured silane coupling agent (KH560) and stir for 10 minutes to obtain modified talc powder;

[0066] (2) The above 5kg modified mineral powder was mixed with 90kg PBAT resin, 3kg PLA resin, 2kg activated carbon powder (coconut shell activated carbon powder, 960m 20.2 kg of antioxidant 1010 (0.05 kg / g), 0.6 kg of lubricant, and 0.6 kg of ethanol were added to a MIXER blender and stirred at 600 rpm / min for 4 minutes to achieve uniform mixing. The material was then fed into a twin-screw extruder via the main feed method. After water cooling, pelletizing, and drying, a modified PBAT material with high puncture resistance and long edge shear performance was obtained. The specific formulation composition can be found in Table 3. The twin-screw extruder speed was 300 rpm and the extrusion temperature was 150°C. Film blowing mechanical tests and edge shear performance tests were conducted, and the results are shown in Table 4.

[0067] Table 3 Raw materials and dosage (Kg) in Examples 1-5 (S1-S5) and Comparative Examples 1-3 (D1-D3)

[0068] raw materials S1 S2 S3 S4 S5 D1 D2 D3 PBAT resin 90 85 79 70 60 90 90 90 PLA(LX175) 3 5 7 9 12 3 3 3 Modified mineral powder 5 7 10 15 20 / / 5 Mineral powder / / / / / 5 5 / Modified activated carbon powder 2 3 4 6 8 / 2 / activated carbon powder / / / / / 2 / 2 antioxidants 0.2 0.3 0.4 0.5 0.6 0.2 0.2 0.2 lubricant 0.6 0.5 0.4 0.3 0.2 0.6 0.6 0.6

[0069] Table 4 Product performance test results of Examples 1-5 (S1-S5) and Comparative Examples 1-3 (D1-D3)

[0070]

[0071] Compared with Comparative Examples 1-3, the use of modified activated carbon powder and modified mineral powder in Example 1 significantly improved the material's puncture strength and edge shear timeliness, increasing the puncture strength from 2.2-2.4N to 2.6N and the edge shear strength retention rate from 65-73% to 82%. Examples 1-5 demonstrate the significantly superior mechanical properties of the modified PBAT material, including high puncture strength, edge shear strength, and edge shear strength retention. The material prepared by the present invention significantly slows the degradation of edge shear adhesion performance and is suitable for the preparation of biodegradable edge-sealed bags. This product effectively addresses the delayed edge-seal failure phenomenon seen in existing edge-seal bag products, achieving a delayed edge-seal strength of over 80% of the initial edge-seal strength.

[0072] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this field can make several improvements and supplements without departing from the method of the present invention. These improvements and supplements should also be considered within the scope of protection of the present invention.

Claims

1. A modified PBAT material, characterized in that: The modified PBAT material comprises the following components in parts by weight: The modified activated carbon powder is alkaline activated carbon powder activated by strong alkali, and the modified mineral powder is flaky mineral powder modified by silane coupling agent.

2. The modified PBAT material according to claim 1, characterized in that: The PBAT resin has a melt index of 3-25 g / 10 min at 190° C. and 2.16 kg; and / or The melt index of PLA resin at 190°C and 2.16 kg is 3-30 g / 10 min.

3. The modified PBAT material according to any one of claims 1-2, characterized in that: The modified activated carbon powder preparation method comprises the following steps: activating the activated carbon powder under strong alkaline conditions, and then filtering, washing, and drying the activated activated carbon powder to obtain the activated modified activated carbon powder.

4. The modified PBAT material according to claim 3, characterized in that: The activated carbon powder is selected from fruit shell, wood, and coal-based activated carbon powder. Preferably, the activated carbon powder has a specific surface area of ​​≥400 m 2 / g.

5. The modified PBAT material according to any one of claims 1 to 4, characterized in that: The preparation method of the modified mineral powder comprises the following steps: uniformly adding a silane coupling agent into the dried mineral powder, stirring the mixture evenly to fully coat the powder, and thus obtaining the modified mineral powder.

6. The modified PBAT material according to claim 5, characterized in that: The mineral powder is one or a combination of kaolin, talc, and mica. Preferably, the mineral powder diameter-to-thickness ratio is ≥25.

7. The modified PBAT material according to any one of claims 1 to 6, characterized in that: The antioxidant is one or more of antioxidant 1010, antioxidant 168, antioxidant 264, antioxidant 1076, antioxidant B215, and antioxidant B225.

8. The modified PBAT material according to any one of claims 1 to 7, characterized in that: The lubricant is one or more of erucamide, zinc stearate, stearic acid monoglyceride, and ethylene bis stearamide.

9. A method for preparing the modified PBAT material according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: PBAT resin, PLA resin, modified mineral powder, modified activated carbon powder, antioxidant and lubricant are mixed evenly in a high-speed mixer, added into a twin-screw extruder for shear mixing and plasticization, and finally extruded and granulated to obtain a modified PBAT material with high puncture resistance and long edge cutting time.

10. The method according to claim 9, wherein the screw speed is 300-600 rpm and the extrusion temperature is 150°C-180°C.

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