High-strength biodegradable PVC composite film and preparation process thereof

Abstract

This invention relates to the field of polyvinyl chloride (PVC) technology and discloses a high-strength biodegradable PVC composite film and its preparation process. The high-strength biodegradable PVC composite film of this invention comprises 80-95 parts by weight of PVC resin, 5-20 parts by weight of polylactic acid-based polyurethane, and 0.3-2 parts by weight of polylactic acid-grafted PVC. The materials are mixed, extruded, and blow-molded to obtain the high-strength biodegradable PVC composite film. Polylactic acid-grafted PVC can act as a compatibilizer, improving the compatibility between polylactic acid-based polyurethane and PVC resin. The polylactic acid-based polyurethane provides better toughening, significantly improving the tensile strength and elongation at break of the PVC film material.

Description

Technical Field

[0001] This invention relates to the field of polyvinyl chloride technology, specifically to a high-strength biodegradable PVC composite film and its preparation process. Background Technology

[0002] Polyvinyl chloride (PVC) possesses advantages such as good mechanical properties, flame retardancy, water and corrosion resistance, and acid and alkali resistance. It can be manufactured into films, pipes, and plastic alloys, and is widely used in construction, agriculture, and industry. However, as a petroleum-based plastic, PVC is difficult to biodegrade, causing significant pollution. Furthermore, the poor mechanical strength of PVC and its film materials limits their practical applications. Combining PVC with starch, polylactic acid (PLA), and other materials can yield high-performance biodegradable materials. The literature "Synthesis and Biodegradability of Polyvinyl Chloride Grafted with Polylactic Acid" reports on grafting PVC with PLA, which imparts good biodegradability to PVC materials. However, this literature does not address the issue of poor mechanical properties of PVC and its film materials.

[0003] Polyurethane is a high-toughness, high-mechanical-strength polymer widely used in the toughening and modification of materials such as polyvinyl chloride (PVC), polypropylene, and epoxy resin. Combining polyurethane with PVC can yield plastic alloys with even better performance; however, polyurethane and PVC are incompatible systems, making it difficult for polyurethane to effectively exert its toughening and reinforcing effects. Summary of the Invention

[0004] This invention solves the problem that PVC membrane materials do not have biodegradability, while improving the mechanical properties of the membrane materials.

[0005] Technical solution: A high-strength biodegradable PVC composite film and its preparation process, comprising 80-95 parts by weight of polyvinyl chloride resin, 5-20 parts by weight of polylactic acid-based polyurethane, 0.3-2 parts by weight of polylactic acid-grafted polyvinyl chloride, 6-10 parts by weight of plasticizer, 2-3 parts by weight of heat stabilizer, and 1.2-2 parts by weight of lubricant.

[0006] The preparation process is as follows: polyvinyl chloride resin, polylactic acid-based polyurethane, polylactic acid-grafted polyvinyl chloride, plasticizer, heat stabilizer, and lubricant are added to a mixer and mixed, then extruded in a single screw extruder and blow-molded in a blow molding machine to obtain a high-strength biodegradable PVC composite film.

[0007] Furthermore, the temperature of zones 1-6 of the single-screw extruder is 100-185℃, and the screw speed is 50-80 r / min; the blow-up ratio during blow molding is 3-3.5.

[0008] Furthermore, the plasticizer is dioctyl phthalate. The lubricant is any one or a combination of polyethylene wax, calcium stearate, and zinc stearate. The heat stabilizer is a lead salt stabilizer, including any one or a combination of tribasic lead sulfate and dibasic lead phosphite.

[0009] Furthermore, the preparation process of polylactic acid-based polyurethane includes: adding dry polyether polyol, polylactic acid diol, isocyanate monomer, and dibutyltin dilaurate to a reaction vessel, carrying out a prepolymerization reaction at 70-80°C for 2.5-3 hours in a nitrogen atmosphere, then adding a chain extender, continuing the reaction for 40-60 minutes, cooling and discharging to obtain polylactic acid-based polyurethane.

[0010] Furthermore, the molar ratio of polyether polyol, polylactic acid diol, isocyanate monomer, dibutyltin dilaurate, and chain extender is (40-70):(30-60):(260-280):(0.05-0.08):(130-140).

[0011] Furthermore, the polyether polyol is polyethylene glycol or polypropylene glycol.

[0012] Furthermore, the isocyanate monomer is isophorone isocyanate monomer, toluene-2,4-isocyanate monomer, or diphenylmethane-4,4'-isocyanate monomer.

[0013] Furthermore, the chain extender is ethylene glycol, 1,4-butanediol, or 1,6-hexanediol.

[0014] Furthermore, the preparation process of polylactic acid-grafted polyvinyl chloride is as follows: cyclohexanone and 200-300 parts by weight of polylactic acid diol are added to a reaction vessel equipped with a reflux condenser. After heating and stirring to dissolve, 3-4.5 parts by weight of elemental sodium are added. Under a nitrogen atmosphere, the mixture is heated to 150-155°C and reacted for 6-8 hours. Then, the solution is added dropwise to a cyclohexanone solution containing 100 parts by weight of polyvinyl chloride resin. Under a nitrogen atmosphere, the mixture is reacted at 120-140°C for 2-8 hours. After cooling, the solution is poured into ethanol for precipitation. After filtration, the product is extracted with toluene using a Soxhlet extractor and dried to obtain polylactic acid-grafted polyvinyl chloride.

[0015] The beneficial technical effects of this invention are as follows: Polylactic acid-based polyurethane is prepared using polylactic acid diol, isocyanate monomers, etc., as raw materials. This polylactic acid is then blended with polylactic acid-grafted polyvinyl chloride (PVC), a heat stabilizer, PVC resin, etc., and blow-molded into a film to obtain a high-strength biodegradable PVC composite film. The main chain of the polylactic acid-based polyurethane contains biodegradable polylactic acid molecular chains, and the side chains of the polylactic acid-grafted PVC also contain biodegradable polylactic acid molecular chains, endowing the PVC composite material with excellent biodegradable properties.

[0016] The main chain of the polylactic acid-based polyurethane in this invention contains polylactic acid molecular chains, and the side chains of polylactic acid-grafted polyvinyl chloride (PVC) also contain polylactic acid molecular chains, resulting in similar solubility between the two. Since the main chain of the polylactic acid-grafted PVC is a PVC molecular chain, it exhibits excellent compatibility with PVC resin. This allows the polylactic acid-grafted PVC to act as a compatibilizer, improving the compatibility between the polylactic acid-based polyurethane and PVC resin. Furthermore, the polylactic acid-based polyurethane provides better toughening, significantly improving the tensile strength and elongation at break of the PVC film material. Detailed Implementation

[0017] The present invention will be further described below with reference to specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0018] The following polyvinyl chloride resin, grade SG-5, was purchased from Jinan Xiangfeng Weiye Chemical Co., Ltd. Polylactic acid diol, with an average molecular weight of 2000, was purchased from Hubei Shuaiyan Ligao Biomedical Co., Ltd. Polyethylene wax, model PE WAX P208, was purchased from Guangzhou Jinqixin Chemical New Materials Co., Ltd.

[0019] Example 1:

[0020] (1) Add 150 mL of cyclohexanone and 8 g of polylactic acid diol to a reaction vessel equipped with a reflux condenser. After heating and stirring to dissolve, add 1.2 g of elemental sodium. Under a nitrogen atmosphere, heat to 150 °C and reflux for 7 h. Then add the solution dropwise to 150 mL of cyclohexanone solution containing 4 g of polyvinyl chloride resin. Under a nitrogen atmosphere, react at 120 °C for 8 h. After cooling, pour the solution into ethanol for precipitation. After filtration, extract the product with toluene in a Soxhlet extractor and dry to obtain polylactic acid grafted polyvinyl chloride.

[0021] (2) Add 70 mmol of dry polyethylene glycol 2000, 30 mmol of polylactic acid diol, 270 mmol of toluene-2,4-isocyanate and 0.07 mmol of dibutyltin dilaurate to the reaction vessel. In a nitrogen atmosphere, carry out a prepolymerization reaction at 75°C for 2.5 h. Then add 135 mmol of chain extender 1,4-butanediol and continue the reaction for 60 min. Cool and discharge the material to obtain polylactic acid-based polyurethane.

[0022] (3) Add 950g of polyvinyl chloride resin, 50g of polylactic acid-based polyurethane, 3g of polylactic acid-grafted polyvinyl chloride, 100g of plasticizer dioctyl phthalate, 9g of tribasic lead sulfate, 21g of dibasic lead phosphite, 10g of polyethylene wax, and 7g of calcium stearate to a mixer and mix. Then extrude the mixture in a single-screw extruder with temperatures of 100℃, 150℃, 165℃, 175℃, and 185℃ in zones 1-6 and a screw speed of 80r / min. Blow molding is performed in a blow molding machine with a blow-up ratio of 3 to obtain a high-strength biodegradable PVC composite film.

[0023] Example 2:

[0024] (1) Add 150 mL of cyclohexanone and 10 g of polylactic acid diol to a reaction vessel equipped with a reflux condenser. After heating and stirring to dissolve, add 1.5 g of elemental sodium. Heat to 150 °C under a nitrogen atmosphere and react for 8 h. Then add the solution dropwise to 150 mL of cyclohexanone solution containing 4 g of polyvinyl chloride resin. React at 140 °C under a nitrogen atmosphere for 2 h. After cooling, pour the solution into ethanol for precipitation. After filtration, extract the product with toluene in a Soxhlet extractor and dry to obtain polylactic acid grafted polyvinyl chloride.

[0025] (2) Add 60 mmol of dry polyethylene glycol 2000, 40 mmol of polylactic acid diol, 280 mmol of diphenylmethane-4,4'-isocyanate and 0.05 mmol of dibutyltin dilaurate to the reaction vessel. In a nitrogen atmosphere, carry out a prepolymerization reaction at 70°C for 3 h. Then add 130 mmol of chain extender 1,6-hexanediol and continue the reaction for 60 min. Cool and discharge the material to obtain polylactic acid-based polyurethane.

[0026] (3) Add 900g of polyvinyl chloride resin, 100g of polylactic acid-based polyurethane, 12g of polylactic acid-grafted polyvinyl chloride, 75g of plasticizer dioctyl phthalate, 8g of tribasic lead sulfate, 18g of dibasic lead phosphite, 12g of polyethylene wax, and 8g of zinc stearate to a mixer and mix. Then extrude the mixture in a single-screw extruder with temperatures of 100℃, 150℃, 165℃, 175℃, and 185℃ in zones 1-6 and a screw speed of 50r / min. Blow molding is performed in a blow molding machine with a blow-up ratio of 3.5 to obtain a high-strength biodegradable PVC composite film.

[0027] Example 3:

[0028] (1) Add 150 mL of cyclohexanone and 12 g of polylactic acid diol to a reaction vessel equipped with a reflux condenser. After heating and stirring to dissolve, add 1.8 g of elemental sodium. Heat to 150 °C under a nitrogen atmosphere and react for 8 h. Then add the solution dropwise to 150 mL of cyclohexanone solution containing 4 g of polyvinyl chloride resin. React at 130 °C under a nitrogen atmosphere for 6 h. After cooling, pour the solution into ethanol for precipitation. After filtration, extract the product with toluene in a Soxhlet extractor and dry to obtain polylactic acid grafted polyvinyl chloride.

[0029] (2) Add 40 mmol of dry polypropylene glycol 2000, 60 mmol of polylactic acid diol, 260 mmol of isophorone isocyanate and 0.08 mmol of dibutyltin dilaurate to the reaction vessel. In a nitrogen atmosphere, carry out a prepolymerization reaction at 80°C for 2.5 h. Then add 130 mmol of chain extender ethylene glycol and continue the reaction for 40 min. Cool and discharge the material to obtain polylactic acid-based polyurethane.

[0030] (3) Add 800g of polyvinyl chloride resin, 200g of polylactic acid-based polyurethane, 20g of polylactic acid-grafted polyvinyl chloride, 60g of plasticizer dioctyl phthalate, 7g of tribasic lead sulfate, 13g of dibasic lead phosphite, 7g of polyethylene wax, and 5g of calcium stearate to a mixer and mix. Then extrude the mixture in a single-screw extruder with temperatures of 100℃, 150℃, 165℃, 175℃, and 185℃ in zones 1-6 and a screw speed of 50r / min. Blow molding is performed in a blow molding machine with a blow-up ratio of 3 to obtain a high-strength biodegradable PVC composite film.

[0031] The biodegradability was tested according to the method specified in GB / T 19277.2-2013, and the test period was 90 days.

[0032] Table 1. Biodegradability Test of PVC Composite Film

[0033]

[0034] After testing, it was found that polylactic acid-based polyurethane was added to the PVC composite materials of Examples 1-3. Its main chain contains biodegradable polylactic acid molecular chains, and the side chains of the polylactic acid-grafted polyvinyl chloride contain biodegradable polylactic acid molecular chains, which endows the PVC composite materials with excellent biodegradability, and the biodegradation rate reaches 11.5-18.6% after 90 days.

[0035] Comparative Example 1: The difference between this comparative example and Example 1 is that polylactic acid-based polyurethane and polylactic acid-grafted polyvinyl chloride are not added.

[0036] (1) 950g of polyvinyl chloride resin, 100g of plasticizer dioctyl phthalate, 9g of tribasic lead sulfate, 21g of dibasic lead phosphite, 10g of polyethylene wax and 7g of calcium stearate were added to a mixer and mixed. Then the mixture was extruded in a single screw extruder with temperatures of 100℃, 150℃, 165℃, 175℃ and 185℃ in zones 1-6 and screw speed of 80r / min. The mixture was blown in a blow molding machine with a blow ratio of 3 to obtain a PVC composite film.

[0037] Comparative Example 2: The difference between this comparative example and Example 1 is that polylactic acid-based polyurethane is not added.

[0038] (1) 950g of polyvinyl chloride resin, 50g of polylactic acid-based polyurethane, 100g of plasticizer dioctyl phthalate, 9g of tribasic lead sulfate, 21g of dibasic lead phosphite, 10g of polyethylene wax, and 7g of calcium stearate were added to a mixer and mixed. Then, the mixture was extruded in a single-screw extruder with temperatures of 100℃, 150℃, 165℃, 175℃, and 185℃ in zones 1-6 and a screw speed of 80r / min. The mixture was then blow-molded in a blow molding machine with a blow-up ratio of 3 to obtain a PVC composite film.

[0039] Comparative Example 3: The difference between this comparative example and Example 1 is that polylactic acid diol is not added when preparing polyurethane.

[0040] (1) Add 100 mmol of dry polyethylene glycol 2000, 270 mmol of toluene-2,4-isocyanate and 0.07 mmol of dibutyltin dilaurate to the reaction vessel. In a nitrogen atmosphere, carry out a prepolymerization reaction at 75°C for 2.5 h. Then add 135 mmol of chain extender 1,4-butanediol and continue the reaction for 60 min. Cool and discharge the material to obtain polyurethane.

[0041] (2) 950g of polyvinyl chloride resin, 50g of polyurethane, 3g of polylactic acid-grafted polyvinyl chloride, 100g of plasticizer dioctyl phthalate, 9g of tribasic lead sulfate, 21g of dibasic lead phosphite, 10g of polyethylene wax, and 7g of calcium stearate were added to a mixer and mixed. Then, the mixture was extruded in a single-screw extruder with temperatures of 100℃, 150℃, 165℃, 175℃, and 185℃ in zones 1-6 and a screw speed of 80r / min. The mixture was then blow-molded in a blow molding machine with a blow-up ratio of 3 to obtain a PVC composite film.

[0042] The tensile properties of PVC composite films were tested according to the method specified in GB / T 1040.3-2006.

[0043] Table 2 Tensile Properties Test of Composite Film

[0044]

[0045] Tests showed that the PVC film material in Comparative Example 1 had low transverse and longitudinal tensile strength, as well as low elongation at break, indicating poor mechanical properties.

[0046] In Comparative Example 2, polylactic acid-based polyurethane was added to the PVC film material. However, its compatibility with polyvinyl chloride resin is very poor, making it difficult to effectively improve the tensile properties of the PVC film material. Although the elongation at break is improved, the tensile strength is significantly reduced.

[0047] The PVC film materials in Examples 1-3 incorporate polylactic acid-based polyurethane and polylactic acid-grafted polyvinyl chloride (PVC). The main chain of the polylactic acid-based polyurethane contains polylactic acid molecular chains, and the side chains of the PVC-grafted polyvinyl chloride also contain polylactic acid molecular chains, resulting in similar solubility between the two. The main chain of the PVC-grafted polyvinyl chloride is a polyvinyl chloride molecular chain, which has excellent compatibility with polyvinyl chloride resin. This allows the PVC-grafted polyvinyl chloride to act as a compatibilizer, improving the compatibility between the polylactic acid-based polyurethane and the polyvinyl chloride resin. The polylactic acid-based polyurethane can also provide better toughening, significantly improving the tensile strength and elongation at break of the PVC film material.

[0048] In Comparative Example 3, no polylactic acid diol was added during the preparation of polyurethane, resulting in the absence of polylactic acid molecular chains in the main molecular chain. As a result, the polylactic acid grafted onto polyvinyl chloride could not act as a compatibilizer and could not improve the compatibility between polylactic acid-based polyurethane and polyvinyl chloride resin. Consequently, the toughening of the polyurethane was poor, and the tensile strength and elongation at break of the PVC film material were low.

[0049] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A high-strength biodegradable PVC composite film, characterized in that, The high-strength biodegradable PVC composite film comprises 80-95 parts by weight of polyvinyl chloride resin, 5-20 parts by weight of polylactic acid-based polyurethane, 0.3-2 parts by weight of polylactic acid-grafted polyvinyl chloride, 6-10 parts by weight of plasticizer, 2-3 parts by weight of heat stabilizer, and 1.2-2 parts by weight of lubricant. The preparation process of the polylactic acid-based polyurethane includes: adding dry polyether polyol, polylactic acid diol, isocyanate monomer, and dibutyltin dilaurate to a reaction vessel, carrying out a prepolymerization reaction in a nitrogen atmosphere, then adding a chain extender, continuing the reaction, cooling and discharging to obtain polylactic acid-based polyurethane. The preparation process of polylactic acid-grafted polyvinyl chloride is as follows: cyclohexanone and 200-300 parts by weight of polylactic acid diol are added to a reaction vessel equipped with a reflux condenser. After heating and stirring to dissolve, 3-4.5 parts by weight of elemental sodium are added. Under a nitrogen atmosphere, the mixture is heated to 150-155°C and reacted for 6-8 hours. Then, the solution is added dropwise to a cyclohexanone solution containing 100 parts by weight of polyvinyl chloride resin. Under a nitrogen atmosphere, the mixture is reacted at 120-140°C for 2-8 hours. After cooling, the solution is poured into ethanol for precipitation. After filtration, the product is extracted with toluene using a Soxhlet extractor and dried to obtain polylactic acid-grafted polyvinyl chloride.

2. The high-strength biodegradable PVC composite film according to claim 1, characterized in that, The plasticizer is dioctyl phthalate, and the lubricant is any one or a combination of polyethylene wax, calcium stearate, and zinc stearate.

3. The high-strength biodegradable PVC composite film according to claim 1, characterized in that, The heat stabilizer is a lead salt stabilizer, including any one or a combination of tribasic lead sulfate and dibasic lead phosphite.

4. The high-strength biodegradable PVC composite film according to claim 1, characterized in that, The prepolymerization reaction is carried out at a temperature of 70-80℃ for 2.5-3 hours, followed by a further reaction time of 40-60 minutes.

5. The high-strength biodegradable PVC composite film according to claim 1, characterized in that, The molar ratio of the polyether polyol, polylactic acid diol, isocyanate monomer, dibutyltin dilaurate, and chain extender is (40-70):(30-60):(260-280):(0.05-0.08):(130-140).

6. The high-strength biodegradable PVC composite film according to claim 5, characterized in that, The polyether polyol is polyethylene glycol or polypropylene glycol; the isocyanate monomer is isophorone isocyanate monomer, toluene-2,4-isocyanate monomer or diphenylmethane-4,4'-isocyanate monomer.

7. The high-strength biodegradable PVC composite film according to claim 5, characterized in that, The chain extender is ethylene glycol, 1,4-butanediol, or 1,6-hexanediol.

8. A preparation process for a high-strength biodegradable PVC composite film as described in any one of claims 1-7, characterized in that, The preparation process includes: adding polyvinyl chloride resin, polylactic acid-based polyurethane, polylactic acid-grafted polyvinyl chloride, plasticizer, heat stabilizer, and lubricant into a mixer and mixing them, then extruding them in a single-screw extruder and blow molding them in a blow molding machine to obtain a high-strength biodegradable PVC composite film.

9. The preparation process of the high-strength biodegradable PVC composite film according to claim 8, characterized in that, The temperature of zones 1-6 of the single-screw extruder is 100-185℃, and the screw speed is 50-80 r / min; the blow-up ratio during blow molding is 3-3.5.

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