Degradable PBAT modified material and preparation method and application thereof

Abstract

The invention provides a degradable PBAT modified material and a preparation method and application thereof. The material comprises the following components: PBAT resin, PETG resin, a decomposing agent, a cross-linking agent and a slipping agent. The PBAT is partially decomposed to generate reaction functional groups, the PETG resin and the cross-linking agent are doped into the PBAT for blending reaction by using double screws, so that the polarity and the high-temperature heat resistance of the material are enhanced, the film still keeps the hardness at a certain temperature, the heat shrinkage rate is increased, film blowing processing is performed for one-time forming, and compared with a conventional PBAT heat shrinkage film, the heat shrinkage rate and the fastening performance are obviously improved, and the service life of the film is prolonged. And the processing is stable.

Description

Technical Field

[0001] The present invention belongs to the field of degradable plastics, and specifically relates to a degradable PBAT modified material and a preparation method and application thereof. Background Art

[0002] Since its invention in the 20th century, plastic has rapidly become one of the most widely used materials worldwide due to its lightweight, durable, and low-cost properties. It is widely used in packaging, agriculture, healthcare, and consumer products. However, traditional plastics rely on petroleum-based raw materials and are difficult to biodegrade naturally, leading to serious environmental problems. According to statistics, over 300 million tons of plastic waste are generated globally each year, of which approximately 80% ends up in landfills or enters natural ecosystems, posing a long-term threat to soil, marine life, and human health.

[0003] PBAT, one of the most widely used biodegradable plastics, boasts excellent tensile strength, easy processability, and complete biodegradability. In the heat shrink film industry, PBAT suffers from issues such as high density, low hardness, poor heat shrinkage, and low heat shrinkage temperature. However, the current price difference between PBAT and PE is within an acceptable range. Therefore, the development of biodegradable heat shrink films with high shrinkage, high hardness, and easy processability holds significant market potential.

[0004] Patent CN115674626B discloses a method for preparing biodegradable heat-shrinkable film, using a blend of PBAT and polylactic acid and biaxial stretching. This method requires higher equipment requirements and is too limited to be suitable for most downstream customers. Patent CN116731298B discloses a modified polylactic acid copolyester, which uses a poly (L-lactic acid) prepolymer component (a), a flexible degradable polyester component (b), and a poly (racemic) lactic acid prepolymer component (c) copolymerized with a chain extender to form a linear modified polylactic acid copolyester. This solution requires polymerization and is relatively costly, failing to meet the low-cost needs of downstream customers.

[0005] Therefore, it is very necessary to optimize the PBAT substrate and develop a biodegradable heat shrinkable film with one-time film blowing and high shrinkage. Summary of the Invention

[0006] In order to solve the above-mentioned problems existing in the prior art, one of the objectives of the present invention is to provide a degradable PBAT modified material, which maintains a longitudinal and transverse thermal shrinkage rate of >70% / 30%, and the film hardness and heat resistance are close to those of polyethylene film, and the toughness is significantly better than that of a pure PLA film system. It is also simple to process and has low cost, meeting the normal thermal shrinkage requirements.

[0007] In order to achieve the above technical effects, the technical solutions adopted by the present invention are as follows:

[0008] A biodegradable PBAT modified material comprises the following raw materials in parts by weight:

[0009] 75-95 parts of PBAT resin, preferably 85-95 parts;

[0010] 5 to 15 parts of PETG resin, preferably 5 to 10 parts;

[0011] 0.3-2 parts of decomposition agent, preferably 0.5-0.8 parts;

[0012] 1 to 10 parts, preferably 3 to 7 parts, of a cross-linking agent;

[0013] 0.1 to 0.5 parts of lubricant, preferably 0.2 to 0.4 parts.

[0014] In one embodiment of the present invention, the weight average molecular weight of the PBAT resin is 100,000 to 150,000, and the acid value is 10 to 40 mol / t; preferably, the molecular weight is 120,000 to 130,000, and the acid value is 20 to 30 mol / t.

[0015] In one embodiment of the present invention, the PETG resin is NPG type PETG, with an acid value of 10-40 mol / t and an intrinsic viscosity of 0.68-0.88 dL / g, preferably an acid value of 10-20 mol / t and an intrinsic viscosity of 0.76-0.78 dL / g.

[0016] In one embodiment of the present invention, the crosslinking agent is a C5-C10 diamino polar cyclic compound, preferably 2,5-bis(aminomethyl)furan and / or 2,5-bis(aminomethyl)tetrahydrofuran, more preferably 2,5-bis(aminomethyl)furan.

[0017] In one embodiment of the present invention, the decomposition agent is a dicarboxylic acid compound and / or a tricarboxylic acid compound having good compatibility with the degradable system, preferably one or more of citric acid, succinic acid, terephthalic acid or their C3-C10 homologues (such as adipic acid, malonic acid, etc.), more preferably citric acid;

[0018] In one embodiment of the present invention, the lubricant is an amide lubricant, preferably one or more of erucamide, oleamide, and behenamide, more preferably erucamide.

[0019] Another object of the present invention is to provide a method for preparing a degradable PBAT modified material.

[0020] A method for preparing a degradable PBAT modified material, wherein the modified material is the above-mentioned material, and the preparation method comprises the following steps: after mixing part of PBAT and a lubricant, the mixture is fed into a twin-screw extruder through a side feed port; after mixing the remaining PBAT resin, PETG resin, a decomposer, and a cross-linking agent, the mixture is fed into the twin-screw extruder through a main feed port; after extrusion, the mixture is water-cooled and granulated to obtain the degradable PBAT modified material.

[0021] In one embodiment of the present invention, the mass ratio of part of the PBAT to the remaining PBAT resin is (5-10): (65-85); the temperature of the twin-screw extruder is 180-200° C., and the screw speed is 300-500 rpm.

[0022] Another object of the present invention is to provide a use of a degradable PBAT modified material.

[0023] A use of a degradable PBAT modified material, wherein the modified material is the above-mentioned material, or a material prepared by the above-mentioned preparation method, and the modified material is used to prepare a film material, preferably for preparing a shrink film.

[0024] Another object of the present invention is to provide a shrink film.

[0025] A shrink film is prepared using the above-mentioned degradable PBAT modified material, or the degradable PBAT modified material prepared using the above-mentioned preparation method, and the shrink film has a longitudinal and transverse heat shrinkage rate greater than 65% / 25%, preferably greater than 70% / 30%.

[0026] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0027] By enhancing the polarity of PBAT and improving the heat resistance of the material, the present invention can maintain a longitudinal and transverse heat shrinkage rate of >70% / 30% compared to conventional degradable heat shrinkable films. The heat shrinkage rate is significantly improved, and the toughness is significantly better than that of PLA film. In addition, the processing is simple and the cost is low, meeting the normal heat shrinkage usage requirements. DETAILED DESCRIPTION

[0028] 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.

[0029] 1. The sources of the main raw materials in the examples and comparative examples of the present invention are as follows:

[0030] PBAT resin: Wanhua Chemical;

[0031] Citric acid: Sinopharm Group;

[0032] PETG resin: China Resources Chemical;

[0033] 2,5-Bis(aminomethyl)furan: Inokane Co., Ltd.;

[0034] 2,5-Bis(aminomethyl)tetrahydrofuran: Inokane Co., Ltd.;

[0035] Erucamide: Paisvi Biotechnology (Shanghai) Co., Ltd.

[0036] 2. The main test methods used in the examples and comparative examples of the present invention are as follows:

[0037] The mechanical properties of the films were tested using an Instron 5966 universal material tester according to the national standard GB / T 1040.3-2006; the gauge length was 100 mm, the tensile speed was 500 mm / min, the sample width was 15 mm, the length was 150 mm, the test temperature was 23° C., and the humidity was 50%.

[0038] Shrinkage test: Test the thermal shrinkage of the film in accordance with the national standard GB / T 4456-2008.

[0039] Heat resistance test: Test the material's heat deformation temperature in accordance with the national standard GB / T 1634-2004.

[0040] 3. The main equipment information used in the embodiments and comparative examples of the present invention is as follows:

[0041] Twin-screw extruder: screw diameter 32 mm, aspect ratio 52, Coperion, ZSK Mv PLUS;

[0042] Film blowing machine: screw diameter 35 mm, aspect ratio 32, die diameter 80 mm, die gap 0.2 mm, Zhejiang Yunfeng Machinery Factory, YFFE-800.

[0043] Example 1

[0044] Preparation of degradable PBAT modified material, the steps are:

[0045] Weigh 10 kg of PBAT resin with a weight-average molecular weight of 120,000 and an acid value of 30 mol / t, and 0.3 kg of erucamide, mix them in a low-pressure mixer at a stirring speed of 20 r / min, and feed them into the twin-screw extruder through the side feed of the sixth zone of the barrel; weigh 72.1 kg of PBAT resin, 10 kg of NPG-type PETG resin with an intrinsic viscosity of 0.78 dL / g and an acid value of 20 mol / t, 7 kg of 2,5-bis(aminomethyl)furan, and 0.6 kg of citric acid, mix them in a low-pressure mixer at a speed of 20 r / min, and feed them into the twin-screw extruder as the main feed.

[0046] The heating zone of the twin-screw extruder is divided into 14 zones, and the temperature is set to 180-200°C; the heating zone of the twin-screw extruder is divided into 14 zones, the temperatures of zones 1 to 6 are set to 180°C, 180°C, 180°C, 190°C, 190°C, 190°C, the temperatures of zones 7 to 10 are set to 200°C, 200°C, 200°C, 200°C, the temperatures of zones 11 to 14 are set to 190°C, 190°C, 190°C, 190°C, the side feeding port is set in the sixth zone, and the screw speed is set to 500r / min.

[0047] After extrusion by a twin-screw extruder, the product is water-cooled and granulated to obtain a biodegradable PBAT modified material.

[0048] The above-mentioned biodegradable PBAT modified material was extruded by a single-screw film blowing machine to produce a PBAT modified film material; the single-screw extruder includes 5 partitions, the temperature settings are 160°C, 180°C, 180°C, 180°C, and 170°C, the blow-up ratio is set to 3, and the production capacity is set to 40kg / h; the film thickness is set to 0.003mm; the performance test results of the obtained film material are shown in Table 1.

[0049] Example 2

[0050] Preparation of degradable PBAT modified material, the steps are:

[0051] Weigh 10 kg of PBAT resin with a weight-average molecular weight of 140,000 and an acid value of 20 mol / t, and 0.4 kg of erucamide, mix them in a low-pressure mixer at a stirring speed of 20 r / min, and feed them into the twin-screw extruder through the side feed of the sixth zone of the barrel; weigh 81.1 kg of PBAT resin, 10 kg of NPG-type PETG resin with an intrinsic viscosity of 0.76 dL / g and an acid value of 15 mol / t, 3 kg of 2,5-bis(aminomethyl)furan, and 0.6 kg of citric acid, mix them in a low-pressure mixer at a speed of 20 r / min, and feed them into the twin-screw extruder as the main feed.

[0052] In the present invention, the heating zone of the twin-screw extruder is divided into 14 zones, and the temperature is set to 180-200°C; wherein the heating zone of the twin-screw extruder is divided into 14 zones, the temperatures of zones 1 to 6 are set to 180°C, 180°C, 180°C, 190°C, 190°C, 190°C, the temperatures of zones 7 to 10 are set to 200°C, 200°C, 200°C, 200°C, and the temperatures of zones 11 to 14 are set to 190°C, 190°C, 190°C, 190°C, wherein the side feed port is set in the sixth zone, and the screw speed is set to 500r / min.

[0053] After extrusion by a twin-screw extruder, the product is water-cooled and granulated to obtain a biodegradable PBAT modified material.

[0054] The above-mentioned biodegradable PBAT modified material was extruded by a single-screw film blowing machine to produce a PBAT modified film material; the single-screw extruder includes 5 partitions, the temperature settings are 160°C, 180°C, 180°C, 180°C, and 170°C, the blow-up ratio is set to 3, and the production capacity is set to 40kg / h; the film thickness is set to 0.003mm; the performance test results of the obtained film material are shown in Table 1.

[0055] Example 3

[0056] Preparation of degradable PBAT modified material, the steps are:

[0057] Weigh 10 kg of PBAT resin with a weight-average molecular weight of 100,000 and an acid value of 20 mol / t, and 0.3 kg of erucamide, mix them in a low-pressure mixer at a stirring speed of 20 r / min, and feed them into the twin-screw extruder through the side feed of the sixth zone of the barrel; weigh 70.9 kg of PBAT resin, 8 kg of NPG-type PETG resin with an intrinsic viscosity of 0.77 dL / g and an acid value of 10 mol / t, 10 kg of 2,5-bis(aminomethyl)tetrahydrofuran, and 0.8 kg of citric acid, mix them in a low-pressure mixer at a speed of 20 r / min, and feed them into the twin-screw extruder as the main feed.

[0058] In the present invention, the heating zone of the twin-screw extruder is divided into 14 zones, and the temperature is set to 180-200°C; wherein the heating zone of the twin-screw extruder is divided into 14 zones, the temperatures of zones 1 to 6 are set to 180°C, 180°C, 180°C, 190°C, 190°C, 190°C, the temperatures of zones 7 to 10 are set to 200°C, 200°C, 200°C, 200°C, and the temperatures of zones 11 to 14 are set to 190°C, 190°C, 190°C, 190°C, wherein the side feed port is set in the sixth zone, and the screw speed is set to 500r / min.

[0059] After extrusion by a twin-screw extruder, the product is water-cooled and granulated to obtain a biodegradable PBAT modified material.

[0060] The above-mentioned biodegradable PBAT modified material was extruded by a single-screw film blowing machine to produce a PBAT modified film material; the single-screw extruder includes 5 partitions, the temperature settings are 160°C, 180°C, 180°C, 180°C, and 170°C, the blow-up ratio is set to 3, and the production capacity is set to 40kg / h; the film thickness is set to 0.003mm; the performance test results of the obtained film material are shown in Table 1.

[0061] Comparative Example 1

[0062] Referring to the method of Example 1, the only difference is that 2,5-bis(aminomethyl)furan is not added, and other operations and conditions remain unchanged to obtain a PBAT modified material, which is then extruded into a film.

[0063] The performance test results of the obtained membrane material are shown in Table 1.

[0064] Comparative Example 2

[0065] Referring to the method of Example 1, the only difference is that no PETG resin is added, and other operations and conditions remain unchanged to obtain a PBAT modified material and extrude it into a film.

[0066] The performance test results of the obtained membrane material are shown in Table 1.

[0067] Comparative Example 3

[0068] Referring to the method of Example 1, the only difference is that citric acid is not added, and other operations and conditions remain unchanged to obtain a PBAT modified material and extrude it into a film.

[0069] The performance test results of the obtained membrane material are shown in Table 1.

[0070] Table 1 Test results of mechanical and thermal shrinkage properties of membrane materials in various embodiments and comparative examples

[0071]

[0072] PBAT resin is directly blown into film, with a heat shrinkage rate of about 24% / 10%, which has a poor heat shrinkage effect. In addition, the film modulus is too low and the heat resistance is insufficient. After entering the oven, it is easily deformed by heat, and it is impossible to achieve tight shrinkage of the wrapped object, which cannot meet the requirements for shrink film use. As shown in Table 1, after modification of Examples 1-3 of the present invention, the film modulus is significantly improved, the heat resistance and heat shrinkage rate are enhanced, the tightness is good, and compared with the traditional PE single bubble heat shrink film, the shrinkage rate is higher, reaching 70% in the longitudinal direction and 30% in the transverse direction. At the same time, it can be verified from Example 1 and Comparative Example 1 that without the addition of 2,5-bis(aminomethyl)furan, the film modulus and heat resistance are significantly reduced. The heat shrinkage rate also declines due to the decrease in film hardness and the reduction in molding stress retention rate. In fact, due to the strong polarity of the 2,5-bis(aminomethyl)furan functional group, the cohesive energy of the embedded molecular chain reinforcement material will significantly reduce the chain movement ability of the material at a certain temperature, retaining the film blowing stress to achieve a dual improvement in tightness and heat shrinkage rate. Example 1 and Comparative Example 2 verify that the addition of PETG resin can further enhance the thermal shrinkage of the material. This is actually due to the excellent compatibility of amorphous PETG with PBAT, which also limits the crystallization of PBAT to enhance the thermal shrinkage of the material. Example 1 and Comparative Example 3 verify that the chain extension reaction can only occur more efficiently after the material is partially degraded by citric acid.

Claims

1. A degradable PBAT modified material, characterized in that: Contains the following raw materials in parts by weight: 75-95 parts of PBAT resin, preferably 85-95 parts; 5 to 15 parts of PETG resin, preferably 5 to 10 parts; 0.3-2 parts of decomposition agent, preferably 0.5-0.8 parts; 1 to 10 parts, preferably 3 to 7 parts, of a cross-linking agent; 0.1 to 0.5 parts of lubricant, preferably 0.2 to 0.4 parts.

2. The modified material according to claim 1, characterized in that The weight average molecular weight of the PBAT resin is 100,000 to 150,000, and the acid value is 10 to 40 mol / t; preferably, the molecular weight is 120,000 to 130,000, and the acid value is 20 to 30 mol / t; And / or, the PETG resin is NPG type PETG, preferably the PETG resin has an acid value of 10-40 mol / t and an intrinsic viscosity of 0.68-0.88 dL / g, more preferably an acid value of 10-20 mol / t and an intrinsic viscosity of 0.76-0.78 dL / g.

3. The modified material according to claim 1 or 2, characterized in that The cross-linking agent is a C5-C10 diamino polar cyclic molecule, preferably 2,5-di(aminomethyl)furan and / or 2,5-bis(aminomethyl)tetrahydrofuran.

4. The modified material according to any one of claims 1 to 3, characterized in that The decomposition agent is a dicarboxylic acid compound and / or a tricarboxylic acid compound, preferably one or more of citric acid, succinic acid, terephthalic acid or their C3-C10 homologues, more preferably citric acid; And / or, the lubricant is an amide lubricant, preferably one or more of erucamide, oleamide, and behenamide.

5. A method for preparing the degradable PBAT modified material according to any one of claims 1 to 4, characterized in that: The preparation method comprises the following steps: After mixing part of the PBAT resin and the lubricant, they enter the twin-screw extruder through the side feed port. After mixing the remaining PBAT resin, PETG resin, decomposer, and cross-linking agent, they enter the twin-screw extruder through the main feed port. After extrusion, they are water-cooled and granulated to obtain a biodegradable PBAT modified material. Preferably, the mass ratio of part of the PBAT resin to the remaining PBAT resin is (5-10): (65-85).

6. A use of a degradable PBAT modified material, wherein the modified material is the material according to any one of claims 1 to 4, or the material prepared by the preparation method according to claim 5, and the modified material is used to prepare a film material, preferably for preparing a shrink film.

7. A shrink film, wherein the shrink film is prepared using the degradable PBAT modified material according to any one of claims 1 to 4, or the degradable PBAT modified material prepared by the preparation method according to claim 5, and the shrink film has a longitudinal and transverse heat shrinkage rate greater than 65% / 25%.

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