Pbat / starch / coffee ground biodegradable composite material and preparation method and application thereof

Abstract

The application belongs to the technical field of biodegradable materials, and discloses a PBAT / starch / coffee residue biodegradable composite material and a preparation method and application thereof.The composite material is composed of the following components in parts by mass: PBAT 50-150 parts, high-straight-chain thermoplastic starch 20-50 parts, coupled coffee residue micro powder 5-20 parts, opening agent 1-5 parts, and compatibility agent 1-10 parts.The high-straight-chain thermoplastic starch and the coupled coffee residue micro powder are prepared by steps, and then blended with PBAT, so that the method has low energy consumption, high mixing efficiency, and the prepared composite material has excellent performance, the tensile strength can reach 25-26.9 MPa, the elongation at break can reach 368-429%, and the composite material has a good application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of biodegradable materials, and particularly relates to a PBAT / starch / coffee residue biodegradable composite material and a preparation method and application thereof. BACKGROUND

[0002] Fossil-based plastics are widely used, which brings great convenience to people, but they are difficult to degrade, leading to serious environmental problems, and an effective way to solve this environmental problem is to develop sustainable green and environmentally friendly biodegradable materials. Polybutylene adipate-co-terephthalate (PBAT) is a new biodegradable polyester with ternary polymerization, which has good biodegradability and good mechanical properties, and is particularly suitable for preparing films, but this material cannot be used alone, and adding a certain amount of biomass material can achieve home composting, which has a wide application prospect.

[0003] Starch is a renewable natural polymer material, and a large number of hydroxyl groups exist in the molecule to form hydrogen bonding, which leads to the fact that natural starch does not have thermoplasticity and is difficult to be thermoplastically processed, which is not conducive to its daily use. Therefore, the starch needs to be modified to have thermoplasticity, but the composite material prepared by blending PBAT and starch is too soft, which leads to insufficient stiffness of the prepared bag, resulting in poor use effect. Therefore, it is necessary to provide a composite material for improving the stiffness of the PBAT and starch blended composite material, which has a good application prospect. SUMMARY

[0004] In order to overcome the shortcomings and deficiencies of the prior art, the primary object of the present application is to provide a PBAT / starch / coffee residue biodegradable composite material.

[0005] Another object of the present application is to provide a preparation method of the PBAT / starch / coffee residue biodegradable composite material.

[0006] Still another object of the present application is to provide the application of the above-mentioned PBAT / starch / coffee residue biodegradable composite material.

[0007] The objects of the present application are achieved by the following technical solutions.

[0008] A PBAT / starch / coffee residue biodegradable composite material, the composite material is composed of the following components by mass fraction:

[0009]

[0010] Preferably, the composite material is composed of the following components by mass fraction:

[0011]

[0012] Preferably, the high straight chain thermoplastic starch is one or more of high straight chain thermoplastic corn starch, high straight chain thermoplastic potato starch, high straight chain thermoplastic sweet potato starch, high straight chain thermoplastic cassava starch, high straight chain thermoplastic wheat starch, high straight chain thermoplastic cassava starch, more preferably high straight chain thermoplastic corn starch and high straight chain thermoplastic potato starch.

[0013] Preferably, the high straight chain thermoplastic starch is prepared from high straight chain starch by thermoplastic processing, the steps are as follows:

[0014] Mix high straight chain starch and shell powder, add to the blender, rotate at 5-10 rpm, add plasticizer, mix and stir to obtain high straight chain thermoplastic starch;

[0015] The high straight chain starch is one or more of high straight chain corn starch, high straight chain potato starch, high straight chain sweet potato starch, high straight chain cassava starch, high straight chain wheat starch, high straight chain cassava starch.

[0016] The content of straight chain in the high straight chain starch is 50-80%, more preferably the content of straight chain in the high straight chain corn starch is 50-75%, and the content of straight chain in the high straight chain potato starch is 60-80%.

[0017] Preferably, the particle size of the shell powder is 3000-5000 mesh, and the amount added is 5-15% of the mass of the high straight chain starch.

[0018] The plasticizer is one or more of acetyl citric acid tributyl ester or polyethylene glycol 400, and the amount added is 15-25% of the mass of the high straight chain starch.

[0019] Preferably, the particle size of the coffee residue powder is 1500-2500 mesh, which is obtained by drying and dehydrating coffee residue, crushing, and then adding a coupling agent for modification.

[0020] Preferably, the coupling agent is acrylic acid or citric acid, and the amount of coupling agent added is 1-3% of the mass of the coffee residue.

[0021] Preferably, the opening agent is one of calcium stearate and oleic acid amide.

[0022] The compatibilizer is one of polyethylene-glycidyl methacrylate (EGMA) and polybutylene adipate-terephthalate-butylene glycol copolymer grafted maleic anhydride (PBAT-g-MAH).

[0023] Preferably, the molecular weight of the PBAT is 50000-70000.

[0024] A method for preparing a PBAT / starch / coffee residue biodegradable composite material, comprising the following steps:

[0025] PBAT / starch / coffee grounds biodegradable composite material is prepared by adding high linear thermoplastic starch, coupled coffee grounds powder and PBAT into a continuous banbury eccentric rotor extruder, and then air-cooling, stretching and cutting into granules after extrusion.

[0026] The preparation method of the PBAT / starch / coffee grounds biodegradable composite material is more specifically:

[0027] Step one: high linear starch is added into a high-speed mixer, shell powder is added, the mixer is started at a speed of 5-10 rpm, plasticizer is slowly added at a material adding port, and the mixture is stirred for 3-5 minutes and then discharged for standby;

[0028] Step two: the temperature of the high-speed mixer is increased to 70-90 DEG C, preferably 80 DEG C, finely ground coffee grounds powder is added, and a coupling agent is added, the mixer is started at a speed of 30-50 rpm, and the mixture is stirred for 10-15 minutes and then discharged for standby;

[0029] Step three: high linear thermoplastic starch, coupled coffee grounds powder and PBAT are added into a continuous banbury eccentric rotor extruder, and then air-cooling, stretching and cutting into granules after extrusion to prepare a PBAT / starch / coffee grounds biodegradable composite material.

[0030] Preferably, the temperature of each section of the extruder is 80 DEG C, 130 DEG C and 130 DEG C, the temperature of the die head is 130 DEG C, and the rotor speed is 20-60 rpm.

[0031] Preferably, the extruder is a continuous banbury eccentric rotor extruder, the diameter of the eccentric rotor is 20-40 mm, and the eccentricity of the rotor is 1-3 mm.

[0032] The PBAT / starch / coffee grounds biodegradable composite material is applied in packaging materials.

[0033] Compared with the prior art, the application has the following advantages and beneficial effects:

[0034] The PBAT / starch / coffee grounds biodegradable composite material is prepared by a method of blending high linear thermoplastic starch, coupled coffee grounds powder and PBAT in steps, coffee grounds are a natural material with renewable and degradable properties, a certain amount of coupled coffee grounds powder is added to improve the stiffness of the film, and the coffee grounds are turned into treasure. The continuous banbury eccentric rotor is used for preparation, and compared with a traditional double-screw extruder, the device has a stretching flow field form in mixing and extrusion, has the advantages of low energy consumption, high mixing efficiency and high performance of the prepared composite material compared with a traditional shearing flow field, the tensile strength of the composite material can reach 25-26.9 MPa, the elongation at break can reach 368-429%, and the composite material has good application prospect. DETAILED DESCRIPTION

[0035] The application will be further described in detail below in connection with specific examples, but the embodiments of the application are not limited thereto, and for the process parameters not specifically indicated, the conventional techniques can be referred to.

[0036] The PBAT has a molecular weight of 60000;

[0037] The high straight chain corn starch has a straight chain content of 50-75%;

[0038] The high straight chain potato starch has a straight chain content of 60-80%;

[0039] The coffee residue is a by-product of coffee bean raw materials, and is prepared into coffee residue powder with a particle size of 2000 after drying and dehydration in an airflow pulverizer.

[0040] The extruder used in the application is a self-made continuous mixing eccentric rotor extruder, wherein the rotor diameter is 30 mm, and the rotor eccentricity is 2 mm.

[0041] Example 1

[0042] The PBAT / starch / coffee residue biodegradable composite material has the following mass ratio of each component: 100 parts of PBAT, 30 parts of high straight chain thermoplastic corn starch, 10 parts of coupled coffee residue powder, 2 parts of calcium stearate and 3 parts of EGMA.

[0043] The high straight chain thermoplastic corn starch is prepared by adding 100 parts of high straight chain corn starch and 10 parts of shell powder (3000 mesh) into a high-speed mixer, starting the mixer at a speed of 5-10 rpm, slowly adding 20 parts of acetyl citric acid tributyl ester at the material adding port, and discharging after stirring for 3-5 minutes.

[0044] The coupled coffee residue powder is prepared by first drying the coffee residue in a forced air drying oven at 100 DEG C for 5 hours, then adding the coffee residue powder with a particle size of 2000 into an airflow pulverizer, and then adding acrylic acid with a mass of 1.5% of the coffee residue into the high-speed mixer to prepare hydrophobic coffee residue powder.

[0045] The above materials are added into the high-speed mixer according to the parts, and after being uniformly mixed, they are added into the continuous mixing eccentric rotor extruder for extrusion and granulation to prepare composite material granules. The temperature is set as 80 DEG C in the first zone, 130 DEG C in the second zone, 130 DEG C in the third zone, and 130 DEG C in the die head, and the screw rotation speed is 15 rpm; the extruded composite material is air-cooled and drawn into a strip, and then cut and granulated to prepare composite material granules.

[0046] Example 2

[0047] A PBAT / starch / coffee grounds biodegradable composite material, the mass fraction ratio of each component of the composite material is specifically: 100 parts of PBAT, 35 parts of high straight chain thermoplastic corn starch, 12 parts of coupled coffee grounds powder, 2 parts of calcium stearate and 3 parts of PBAT-g-MAH.

[0048] The high straight chain thermoplastic corn starch is prepared by adding 100 parts of high straight chain starch, 12 parts of shell powder (3500 mesh) into a high-speed mixer, starting the mixer at a speed of 5-10 rpm, slowly adding 25 parts of acetyl citric acid tributyl ester into the material adding port, and discharging after stirring for 3-5 minutes.

[0049] The coupled coffee grounds powder is prepared by first drying coffee grounds in a blast drying oven at 100℃ for 5h, then adding the coffee grounds into an air flow pulverizer to prepare coffee grounds powder with a mesh size of 2000, and then adding 1.5% of acrylic acid based on the mass of the coffee grounds into a high-speed mixer to prepare hydrophobic coffee grounds powder.

[0050] The above materials are added into a high-speed mixer according to the parts, and after being uniformly mixed, they are added into a continuous banbury eccentric rotor extruder for extrusion and granulation to prepare composite material granules. The temperature is set to be 80℃ for zone 1, 130℃ for zone 2, 130℃ for zone 3, and 130℃ for the die head, and the screw rotation speed is 15 rpm; the extruded composite material is air-cooled and drawn into strips, and then cut and granulated to prepare composite material granules.

[0051] Example 3

[0052] A PBAT / starch / coffee grounds biodegradable composite material, the mass fraction ratio of each component of the composite material is specifically: 100 parts of PBAT, 40 parts of high straight chain thermoplastic potato starch, 15 parts of coupled coffee grounds powder, 2 parts of oleic acid amide and 5 parts of EGMA.

[0053] The high straight chain thermoplastic potato starch is prepared by adding 100 parts of high straight chain starch, 15 parts of shell powder (5000 mesh) into a high-speed mixer, starting the mixer at a speed of 5-10 rpm, slowly adding 25 parts of polyethylene glycol 400 into the material adding port, and discharging after stirring for 3-5 minutes.

[0054] The coupled coffee grounds powder is prepared by first drying coffee grounds in a blast drying oven at 100℃ for 5h, then adding the coffee grounds into an air flow pulverizer to prepare coffee grounds powder with a mesh size of 2000, and then adding 1.5% of citric acid based on the mass of the coffee grounds into a high-speed mixer to prepare hydrophobic coffee grounds powder.

[0055] The above materials are added into a high-speed mixer according to the parts, and after being uniformly mixed, are added to a continuous banbury eccentric rotor extruder for extrusion and granulation to prepare composite material granules. The temperature is set to 80 DEG C in the first zone, 130 DEG C in the second zone, 130 DEG C in the third zone, and 130 DEG C at the die head, and the screw rotation speed is 15 rpm; the extruded composite material is air-cooled and drawn into strips, and is cut and granulated to prepare composite material granules.

[0056] Example 4

[0057] A PBAT / starch / coffee grounds biodegradable composite material, and the mass fraction ratio of each component of the composite material is specifically: 100 parts of PBAT, 45 parts of high-amylose thermoplastic potato starch, 10 parts of coupled coffee grounds powder, 3 parts of oleic acid amide, and 3 parts of PBAT-g-MAH.

[0058] The high-amylose thermoplastic potato starch is prepared by adding 100 parts of high-amylose starch, 12 parts of shell powder (5000 mesh) into a high-speed mixer, starting the mixer at a rotation speed of 5-10 rpm, slowly adding 15 parts of polyethylene glycol 400 and 10 parts of acetyl citric acid tributyl ester at the material adding port, and discharging after 3-5 minutes of stirring.

[0059] The coupled coffee grounds powder is prepared by first drying coffee grounds in a forced air drying oven at 100 DEG C for 5 hours, then adding the coffee grounds into an air flow pulverizer to prepare coffee grounds powder with a particle size of 2000 mesh, and then adding 1.5% of citric acid based on the mass of the coffee grounds into a high-speed mixer to prepare hydrophobic coffee grounds powder.

[0060] The above materials are added into a high-speed mixer according to the parts, and after being uniformly mixed, are added to a continuous banbury eccentric rotor extruder for extrusion and granulation to prepare composite material granules. The temperature is set to 80 DEG C in the first zone, 130 DEG C in the second zone, 130 DEG C in the third zone, and 130 DEG C at the die head, and the screw rotation speed is 15 rpm; the extruded composite material is air-cooled and drawn into strips, and is cut and granulated to prepare composite material granules.

[0061] The materials prepared in Examples 1-4 are subjected to tensile property testing according to GB / T 1040.1-2018 “Determination of tensile properties of plastics”, and the test data are specifically as follows:

[0062] Table 1

[0063]

[0064] The above examples are preferred embodiments of the present application, but the embodiments of the present application are not limited by the above examples, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application should be equivalent replacement methods, and are all included in the protection scope of the present application.

Claims

1. A PBAT / starch / coffee grounds biodegradable composite material, characterized in that, The composite material is composed of the following components in parts by weight: 50-150 PBATs 20-50 parts of high-amylose thermoplastic starch 5-20 parts of conjugated coffee grounds powder 1-5 parts of opening agent 1-10 parts compatibilizer; The high amylose thermoplastic starch is obtained by thermoplastic processing of high amylose starch, as follows: High amylose and shell powder are mixed, added to a mixer, plasticizer is added, and the mixture is stirred to obtain the final product. The coupled coffee grounds powder is obtained by drying, dehydrating, and pulverizing coffee grounds, and then modifying them with a coupling agent; the coupling agent is acrylic acid or citric acid.

2. The PBAT / starch / coffee grounds biodegradable composite material according to claim 1, characterized in that, The composite material is composed of the following components in parts by weight: 100 copies of PBAT 30-45 parts of high-amylose thermoplastic starch 10-15 parts of conjugated coffee grounds powder 2-3 parts of opening agent 3-5 parts compatibilizer.

3. The PBAT / starch / coffee grounds biodegradable composite material according to claim 1, characterized in that, The high-amylose thermoplastic starch is one or more of the following: high-amylose thermoplastic corn starch, high-amylose thermoplastic potato starch, high-amylose thermoplastic sweet potato starch, high-amylose thermoplastic cassava starch, high-amylose thermoplastic wheat starch, and high-amylose thermoplastic cassava starch.

4. The PBAT / starch / coffee grounds biodegradable composite material according to claim 1, characterized in that, The amylose content in the high amylose starch is 50-80%; The amount of shell micropowder added is 5-15% of the mass of high amylose.

5. The PBAT / starch / coffee grounds biodegradable composite material according to claim 1, characterized in that, The particle size of the coupled coffee grounds powder is 1500~2500 mesh.

6. The PBAT / starch / coffee grounds biodegradable composite material according to claim 1, characterized in that, The opening agent is one of calcium stearate and oleamide; The compatibilizer is one of polyethylene-glycidyl methacrylate and PBAT-g-MAH.

7. The method for preparing the PBAT / starch / coffee grounds biodegradable composite material according to any one of claims 1 to 6, characterized in that, Includes the following steps: High linear thermoplastic starch, coupled coffee grounds powder and PBAT were added to a continuous internal mixing eccentric rotor extruder, and after extrusion, air-cooled strands were drawn and pelletized to obtain a PBAT / starch / coffee grounds biodegradable composite material.

8. The method for preparing the PBAT / starch / coffee grounds biodegradable composite material according to claim 7, characterized in that, The extruder has temperatures of 80℃, 130℃, and 130℃ in each section, with a die head temperature of 130℃ and a rotor speed of 20~60rpm.

9. The method for preparing the PBAT / starch / coffee grounds biodegradable composite material according to claim 7, characterized in that, The extruder is a continuous internal mixing eccentric rotor extruder, the diameter of the eccentric rotor is 20~40mm, and the rotor eccentricity is 1~3mm.

10. The application of the PBAT / starch / coffee grounds biodegradable composite material according to any one of claims 1 to 6 in packaging materials.

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