Biodegradable paper-plastic composite material and preparation method thereof

Abstract

The invention discloses a biodegradable paper-plastic composite material and a preparation method thereof. The biodegradable paper-plastic composite material is prepared from the following components in parts by mass: 70-90 parts of poly (butylene adipate-co-terephthalate), 10-30 parts of carbon dioxide-based polyester-polycarbonate and 0.2-0.5 part of a processing aid. Polybutylene adipate terephthalate (PBAT) not only has better mechanical properties, but also has higher ductility and elongation at break, but has the defects of low modulus, easiness in curl deformation, higher melt viscosity, easiness in adhesion to equipment and poor barrier property. PPCP belongs to an amorphous polymer, is high in tensile strength and excellent in barrier property, but is low in elongation at break (-5%), is a brittle polymer and is poor in melt strength, and the higher the temperature is, the poorer the melt strength is. Therefore, the PPCP is ingeniously used for modifying the PBAT blown film, the obtained film combines the properties of the two plastics, the good ductility and elongation at break are kept, the modulus of the film is also improved, and meanwhile, the melt strength is also easy to process.

Description

Technical Field

[0001] The invention relates to the technical field of polymer composite materials, in particular to a biodegradable paper-plastic composite material and a preparation method thereof. Background Art

[0002] Paper-plastic composite materials are materials that combine paper with one or more plastic films through one or more composite processes. The combination of paper and plastic film overcomes the shortcomings of the monomers. The barrier layer of the paper-plastic composite material protects the paper from moisture (or oil resistance), so that the material can meet the food packaging requirements of water-containing or oil-containing foods. Paper-plastic composite materials are non-toxic, odorless, and highly durable. Compared with other packaging materials such as metal cans, glass, and ceramics, they are cheap, light, and easy to package. These advantages make it one of the most popular packaging materials at present, and it is widely used in food, daily chemicals, sanitary products and other industries. Although paper is green and degradable, the film usually uses BOPP, PET, CPP, PE, etc. as the base material, which are all petroleum-based plastics and non-biodegradable plastics. Petroleum is a non-renewable resource and cannot fully meet the needs of low-carbon environmental protection.

[0003] In order to meet the needs of low-carbon and environmental protection, it is necessary to alleviate the three problems of global warming, depletion of oil resources and "white pollution". Polybutylene adipate terephthalate (PBAT), which is copolymerized by rigid aromatic chains (butylene terephthalate) and flexible fatty chains (butylene adipate), is a material with good biodegradability. Due to its good toughness and high elongation, it can be used to produce packaging materials, medical products and agricultural films. However, its low strength and poor barrier properties limit its production and application. Polymethyl ethylene carbonate (PPC) prepared by copolymerization of propylene oxide and carbon dioxide is the most widely studied carbon dioxide-based polymer. It is a recognized biodegradable material with good light transmittance, high barrier properties and high toughness. It has great application prospects in the fields of food packaging and medical materials. However, its low glass transition temperature ( T g =30-40℃) and poor mechanical strength (~9 MPa) limit its large-scale application.

[0004] We prepared a completely biodegradable plastic by copolymerizing phthalic anhydride, propylene oxide and carbon dioxide: carbon dioxide-based polyester-polycarbonate (PPC-P) (Chinese patent CN 111378101 A, J.CO 2 Util. 2021, 49,101558), the prepared PPC-P has good light transmittance, high barrier properties, and a mechanical strength of up to 37 MPa.T g The temperature is 40-55℃, which is higher than that of poly(ethylene methyl carbonate) (PPC). T g (30-40℃) has been greatly improved. The disadvantage is that it has poor toughness and low elongation at break (~5%), and is a brittle material, which also limits its application in the fields of film and food packaging. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a method for preparing a paper-plastic composite material by using a carbon dioxide-based polyester-polycarbonate biodegradable plastic modified film.

[0006] In order to achieve the above object, the present invention adopts the following technical solution: A carbon dioxide-based polyester-polycarbonate biodegradable plastic modified film, comprising the following components in parts by weight: 70-90 parts of polybutylene adipate terephthalate, Carbon dioxide based polyester-polycarbonate 10-30 parts, Processing aid 0.2-0.5 parts.

[0007] Preferably, in the above carbon dioxide-based polyester-polycarbonate biodegradable plastic modified film, it is characterized in that the number average molecular weight of the polybutylene adipate terephthalate is 60-180 kg / mol; Preferably, in the above carbon dioxide-based polyester-polycarbonate biodegradable plastic modified film, the carbon dioxide-based polyester-polycarbonate is a high molecular weight polymer obtained by terpolymerization of carbon dioxide, propylene oxide and phthalic anhydride, and has a number average molecular weight of 40 to 150 kg / mol; its structure is shown in formula (1); wherein m≥1, n≥1, k≥0, m, n, k are all integers;

[0008] Preferably, in the above biodegradable plastic modified film, the processing aid is selected from one or more of BASF multifunctional epoxy chain extender (ADR), erucic acid amide, and 4,4'-diphenylmethane diisocyanate (MDI).

[0009] The method for preparing a paper-plastic composite material using a carbon dioxide-based polyester-polycarbonate biodegradable plastic modified film comprises the following steps: (1) Polybutylene adipate terephthalate, carbon dioxide-based polyester-polycarbonate and a processing aid are melt-blended to obtain a blended plastic, which is then pelletized; wherein the parameters (temperature / rotation speed) of the melt-blending by a twin-screw extruder are 120-150-170-170-170-170-170-170-170°C / 150rpm.

[0010] (2) Extruding the blended pellets into a blown film through a film blowing machine; wherein the parameters (temperature / rotation speed / pulling speed / winding speed) of the blown film extruded through the film blowing machine are 130-130-130-130-130°C / 20rpm / 0.4 rpm / 0.4rpm.

[0011] (3) The blown film and the paper layer are compounded by hot rolling to produce a biodegradable paper-plastic composite material.

[0012] Preferably, the biodegradable plastic modified film has a thickness of 10-50 μm.

[0013] Preferably, the paper layer is paper, and the thickness of the paper layer is 20-400 μm.

[0014] Preferably, the paper material can be selected from a wide range, and is one of sack paper, kraft paper, chicken paper, striped kraft paper, kraft cardboard, lining paper, boxboard, corrugated paper, and honeycomb paperboard.

[0015] Compared with the prior art, the present invention has the following beneficial effects: (1) Polybutylene adipate terephthalate (PBAT) has good mechanical properties, high ductility and elongation at break, but has the disadvantages of low modulus, easy curling and deformation, high melt viscosity, easy adhesion to equipment and poor barrier properties. PPCP is an amorphous polymer with high tensile strength and excellent barrier properties, but its elongation at break is low (~5%), it is a brittle polymer, and its melt strength is poor, and the higher the temperature, the worse the melt strength. Therefore, the present invention cleverly uses PPCP to modify PBAT blown film, and the obtained film combines the properties of the two plastics, retaining good ductility and elongation at break, and the modulus of the film is also improved, while the melt strength becomes easier to process.

[0016] (2) The polybutylene adipate terephthalate, carbon dioxide-based polyester-polycarbonate and paper layer used in the present invention are all biodegradable and green and environmentally friendly.

[0017] (3) The paper-plastic composite material prepared by the present invention can be used for food and medicine packaging, medical operating table cloths, medical sanitary scarves and hotel disposable supplies packaging, etc.

[0018] (4) The present invention uses carbon dioxide-based polyester-polycarbonate as a modifier, which reduces costs compared to pure PBAT film, has high economic efficiency, and is more conducive to industrialization.

[0019] (5) The biodegradable paper-plastic composite material prepared by the present invention has good water vapor barrier properties and processing properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a typical stress-strain curve (MD) of the carbon dioxide-based polyester-polycarbonate biodegradable plastic modified film obtained in Examples 4-6 of the present invention; Figure 2 The typical stress-strain curve (MD) of the bio-based polycarbonate biodegradable plastic modified film obtained in Comparative Examples 1-2 of the present invention; Figure 3 This is a macroscopic schematic diagram of a carbon dioxide-based polyester-polycarbonate biodegradable plastic modified film according to Example 1 of the present invention; Figure 4 This is a macroscopic schematic diagram of the paper-plastic composite material and the pure paper layer obtained in Example 1 of the present invention. DETAILED DESCRIPTION

[0021] Example 1: After polybutylene adipate terephthalate (PBAT number average molecular weight is 60 kg / mol) and carbon dioxide-based polyester-polycarbonate polymer (PPC-P number average molecular weight is 55 kg / mol) are dried in a vacuum drying oven at 80°C for 24 hours, 900 g PBAT, 100 g PPCP and 2 g ADR are simply premixed and then added to a twin-screw extruder to prepare a blended plastic PBAT / 10%PPCP / 0.2%ADR by melt blending. The temperatures of each zone of the extruder are set to 120-150-170-170-170-170-170-170-170°C, the screw speed is preferably set to 150 rpm, and granulation is performed at 80°C. After drying, a mixed plastic is obtained. The mixed plastic is processed by a film blowing machine, and the temperature of each zone of the main machine of the film blowing machine is set to 130-130-130-130-130°C, the screw speed is preferably set to 20rpm, the traction speed is preferably set to 0.4rpm, and the winding speed is preferably set to 0.4rpm. The processed blown film has a thickness of 10-50 μm, and is hot-rolled with paper (thickness of 20-400 μm), the hot rolling pressure is preferably set to 5-18MPa, and the hot rolling temperature is preferably set to 130°C to obtain a paper-plastic composite material with a thickness of 30-450 μm. According to the national standard GBT 30768-2014, the tensile strength, tensile elongation at break and barrier properties of the paper-plastic composite material are tested.

[0022] Example 2: After polybutylene adipate terephthalate (PBAT number average molecular weight is 60 kg / mol) and carbon dioxide-based polyester-polycarbonate polymer (PPC-P number average molecular weight is 55 kg / mol) are dried in a vacuum drying oven at 80°C for 24 hours, 800g PBAT, 200g PPCP and 2g ADR are simply premixed and then added to a twin-screw extruder to prepare a blended plastic PBAT / 20%PPCP / 0.2%ADR by melt blending. The temperatures of each zone of the extruder are set to 120-150-170-170-170-170-170-170-170°C, the screw speed is preferably set to 150rpm, and granulation is performed at 80°C and dried to obtain a mixed plastic. The mixed plastic is processed by a film blowing machine, and the temperature of each zone of the film blowing machine host is set to 130-130-130-130-130°C, the screw speed is preferably set to 20rpm, the traction speed is preferably set to 0.4rpm, and the winding speed is preferably set to 0.4rpm. The processed blown film has a thickness of 10-50 μm, and is hot-rolled with paper (thickness of 20-400 μm), the hot rolling pressure is preferably set to 5-18MPa, and the hot rolling temperature is preferably set to 130°C to obtain a paper-plastic composite material with a thickness of 30-450 μm. According to the national standard GBT 30768-2014, the tensile strength, tensile elongation at break and barrier properties of the paper-plastic composite material are tested.

[0023] Example 3: After polybutylene adipate terephthalate (PBAT number average molecular weight is 60 kg / mol) and carbon dioxide-based polyester-polycarbonate polymer (PPC-P number average molecular weight is 55 kg / mol) are dried in a vacuum drying oven at 80°C for 24 hours, 700 g PBAT, 300 g PPCP and 2 g ADR are simply premixed and then added to a twin-screw extruder to prepare a blended plastic PBAT / 30%PPCP / 0.2%ADR by melt blending. The temperatures of each zone of the extruder are set to 120-150-170-170-170-170-170-170-170°C, the screw speed is preferably set to 150 rpm, and granulation is performed at 80°C and dried to obtain a mixed plastic. The mixed plastic is processed by a film blowing machine, and the temperature of each zone of the main machine of the film blowing machine is set to 130-130-130-130-130°C, the screw speed is preferably set to 20rpm, the traction speed is preferably set to 0.4rpm, and the winding speed is preferably set to 0.4rpm. The processed blown film has a thickness of 10-50μm, and is hot-rolled with paper (thickness of 20-400μm), the hot rolling pressure is preferably set to 5-18MPa, and the hot rolling temperature is preferably set to 130°C to obtain a paper-plastic composite material with a thickness of 30-450μm. According to the national standard GBT 30768-2014, the tensile strength, tensile elongation at break and barrier properties of the paper-plastic composite material are tested.

[0024] Example 4: After polybutylene adipate terephthalate (PBAT number average molecular weight is 60 kg / mol) and carbon dioxide-based polyester-polycarbonate polymer (PPC-P number average molecular weight is 55 kg / mol) are dried in a vacuum drying oven at 80°C for 24 hours, 900 g PBAT, 100 g PPCP and 5 g ADR are simply premixed and then added to a twin-screw extruder to prepare a blended plastic PBAT / 10%PPCP / 0.5%ADR by melt blending. The temperatures of each zone of the extruder are set to 120-150-170-170-170-170-170-170-170°C, the screw speed is preferably set to 150 rpm, and granulation is performed at 80°C and dried to obtain a mixed plastic. The mixed plastic is processed by a film blowing machine, and the temperature of each zone of the main machine of the film blowing machine is set to 130-130-130-130-130°C, the screw speed is preferably set to 20rpm, the traction speed is preferably set to 0.4rpm, and the winding speed is preferably set to 0.4rpm. The processed blown film has a thickness of 10-50μm, and is hot-rolled with paper (thickness of 20-400μm), the hot rolling pressure is preferably set to 5-18MPa, and the hot rolling temperature is preferably set to 130°C to obtain a paper-plastic composite material with a thickness of 30-450μm. According to the national standard GBT 30768-2014, the tensile strength, tensile elongation at break and barrier properties of the paper-plastic composite material are tested.

[0025] Example 5: After polybutylene adipate terephthalate (PBAT number average molecular weight is 60 kg / mol) and carbon dioxide-based polyester-polycarbonate polymer (PPC-P number average molecular weight is 55 kg / mol) are dried in a vacuum drying oven at 80°C for 24 hours, 800g PBAT, 200g PPCP and 5g ADR are simply premixed and then added to a twin-screw extruder to prepare a blended plastic PBAT / 20%PPCP / 0.5%ADR by melt blending. The temperatures of each zone of the extruder are set to 120-150-170-170-170-170-170-170-170°C, the screw speed is preferably set to 150rpm, and the pellets are extruded and dried at 80°C to obtain a mixed plastic. The mixed plastic is processed by a film blowing machine, and the temperature of each zone of the main machine of the film blowing machine is set to 130-130-130-130-130°C, the screw speed is preferably set to 20rpm, the traction speed is preferably set to 0.4rpm, and the winding speed is preferably set to 0.4rpm. The processed blown film has a thickness of 10-50μm, and is hot-rolled with paper (thickness of 20-400μm), the hot rolling pressure is preferably set to 5-18MPa, and the hot rolling temperature is preferably set to 130°C to obtain a paper-plastic composite material with a thickness of 30-450μm. According to the national standard GBT 30768-2014, the tensile strength, tensile elongation at break and barrier properties of the paper-plastic composite material are tested.

[0026] Example 6: After polybutylene adipate terephthalate (PBAT number average molecular weight is 60 kg / mol) and carbon dioxide-based polyester-polycarbonate polymer (PPC-P number average molecular weight is 55 kg / mol) are dried in a vacuum drying oven at 80°C for 24 hours, 700 g PBAT, 300 g PPCP and 5 g ADR are simply premixed and then added to a twin-screw extruder to prepare a blended plastic PBAT / 30%PPCP / 0.5%ADR by melt blending. The temperatures of each zone of the extruder are set to 120-150-170-170-170-170-170-170-170°C, the screw speed is preferably set to 150 rpm, and granulation is performed at 80°C and dried to obtain a mixed plastic. The mixed plastic is processed by a film blowing machine, and the temperature of each zone of the film blowing machine host is set to 130-130-130-130-130°C, the screw speed is preferably set to 20rpm, the traction speed is preferably set to 0.4rpm, and the winding speed is preferably set to 0.4rpm. The processed blown film has a thickness of 10-50μm, and is hot-rolled with paper (thickness of 20-400μm), the hot rolling pressure is preferably set to 5-18 MPa, and the hot rolling temperature is preferably set to 130°C to obtain a paper-plastic composite material with a thickness of 30-450μm. According to the national standard GBT 30768-2014, the tensile strength, tensile elongation at break and water vapor barrier properties of the paper-plastic composite material are tested.

[0027] Comparative Example 1: This comparative example prepares a blow-molded polybutylene adipate terephthalate (PBAT) / polyisosorbate carbonate (PIC) blended film. Among them, the number average molecular weight of PBAT is 60kg / mol, and the number average molecular weight of polyisosorbate carbonate (PIC) is 50kg / mol. After the above raw materials are dried in a vacuum drying oven at 80°C for 24 hours, 800 g PBAT, 200 g PIC and 5 g ADR are simply premixed and then added to a twin-screw extruder. The blended plastic PBAT / 20%PIC / 0.5%ADR is prepared by melt blending, and the temperature of each zone of the extruder is set to 120-150-170-170-170-170-170-170-170-170°C, and the screw speed is preferably set to 150rpm. After extrusion granulation and drying at 80°C, a mixed plastic is obtained. The mixed plastic is processed by a film blowing machine, and the temperature of each zone of the film blowing machine host is set to 130-130-130-130-130°C, the screw speed is preferably set to 20rpm, the traction speed is preferably set to 0.4rpm, and the winding speed is preferably set to 0.4rpm. The processed blown film has a thickness of 10-50 μm. The tensile strength test is carried out according to GB / T 1040.3.

[0028] Comparative Example 2: This comparative example prepares a blow molded polybutylene adipate terephthalate (PBAT) / polylimonene carbonate (PLC) blended film. Among them, the number average molecular weight of PBAT is 60kg / mol, and the number average molecular weight of polylimonene carbonate (PLC) is 80kg / mol. After the above raw materials are dried in a vacuum drying oven at 80°C for 24 hours, 800 g PBAT, 200 g PLC and 5 g ADR are simply premixed and then added to a twin-screw extruder. The blended plastic PBAT / 20%PLC / 0.5%ADR is prepared by melt blending, and the temperature of each zone of the extruder is set to 120-150-170-170-170-170-170-170-170-170°C, and the screw speed is preferably set to 150rpm. After extrusion granulation and drying at 80°C, a mixed plastic is obtained. The mixed plastic is processed by a film blowing machine, and the temperature of each zone of the film blowing machine host is set to 130-130-130-130-130°C, the screw speed is preferably set to 20rpm, the traction speed is preferably set to 0.4rpm, and the winding speed is preferably set to 0.4rpm. The processed blown film has a thickness of 10-50μm. The tensile strength test is carried out according to GB / T 1040.3.

[0029]

[0030] As can be seen from Table 1, the modification effect of PBAT using carbon dioxide-based polyester-polycarbonate (PPCP) is better than that using bio-based polycarbonate (PIC, PLC). The longitudinal tensile strength of the film modified by PPCP and blown out can reach up to 27.9MPa, and the longitudinal elongation at break can reach about 880%, which is about 20-50% higher than that of the film modified by bio-based polycarbonate. The transverse tensile strength can reach up to 24.5MPa, and the longitudinal elongation at break can reach about 780%, which is about 20-50% higher than that of the film modified by bio-based polycarbonate. Figure 1 It can be seen that with the increase of PPCP content, the yield strength of the film is greatly improved, and the modulus of the PBAT film modified with carbon dioxide-based polyester-polycarbonate (PPCP) is greatly improved, which makes the film less likely to break during the packaging process and can better meet the use requirements of packaging films. In addition, carbon dioxide-based polyester-polycarbonate (PPCP) improves the melt strength (MFR reflection) of PBAT to be more suitable for film blowing at lower temperatures, which can reduce energy consumption during the processing and molding process.

[0031]

[0032]

[0033] It can be seen from Table 2 and Table 3 that the mechanical properties and barrier properties of the paper-plastic composite material product obtained in the embodiment are excellent. Referring to the national standard GB / T 30768-2014, the tensile strength (longitudinal ≥20MPa, transverse ≥15MPa) and water vapor barrier (≤25 g / m 2 ·24h) are far beyond the national standard. In addition, compared with the tensile strength (~18MPa) and water vapor barrier (~50 g / m 2 ·24h), there is a significant improvement.

[0034] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A biodegradable paper-plastic composite material, characterized in that Made of the following components in parts by weight: 70-90 parts of polybutylene adipate terephthalate, Carbon dioxide based polyester-polycarbonate 10-30 parts, Processing aid 0.2-0.5 parts.

2. The biodegradable paper-plastic composite material according to claim 1, characterized in that: The number average molecular weight of the polybutylene adipate terephthalate is 60-180 kg / mol.

3. The biodegradable paper-plastic composite material according to claim 1, characterized in that: The carbon dioxide-based polyester-polycarbonate is a high molecular weight polymer obtained by terpolymerization of carbon dioxide, propylene oxide and phthalic anhydride, and has a number average molecular weight of 40 to 150 kg / mol; its structure is shown in formula (1); wherein m≥1, n≥1, k≥0, m, n, k are all integers; 。 4. The biodegradable paper-plastic composite material according to claim 1, characterized in that: The processing aid is selected from one or more of BASF multifunctional epoxy chain extender, erucic acid amide, and 4,4'-diphenylmethane diisocyanate.

5. A method for preparing the biodegradable paper-plastic composite material as claimed in claim 1, characterized in that The steps include: (1) preparing a blended plastic by melt blending polybutylene adipate terephthalate, carbon dioxide-based polyester-polycarbonate and a processing aid, and granulating the blended plastic; wherein the temperature of melt blending by a twin-screw extruder is 120°C-150°C-170°C-170°C-170°C-170°C-170°C-170°C-170°C-170°C, and the rotation speed is 150 rpm; (2) Extruding the blended pellets into a blown film through a film blowing machine; wherein the temperature of the blown film extruded through the film blowing machine is 130°C-130°C-130°C-130°C-130°C, the rotation speed is 20 rpm, the pulling speed is 0.4 rpm, and the winding speed is 0.4 rpm; (3) The blown film and the paper layer are compounded by hot rolling to produce a biodegradable paper-plastic composite material.

6. The method for preparing the biodegradable paper-plastic composite material according to claim 5, characterized in that: The thickness of the blown film is 10-50 μm; the paper layer is paper, and the thickness of the paper layer is 20-400 μm.

7. The method for preparing the biodegradable paper-plastic composite material according to claim 6, characterized in that: The paper is one of paper bag paper, kraft paper, chicken paper, striped kraft paper, kraft cardboard, lining paper, boxboard, corrugated paper and honeycomb paperboard.

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