High-strength biodegradable PVC (polyvinyl chloride) composite film and preparation process thereof

Abstract

The invention relates to the technical field of polyvinyl chloride, and discloses a high-strength biodegradable PVC (polyvinyl chloride) composite film and a preparation process thereof, and 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 and the like. All the materials are mixed, extruded and blow-molded to obtain the high-strength biodegradable PVC composite film. The polylactic acid grafted polyvinyl chloride can be used as a compatilizer to improve the compatibility between the polylactic acid-based polyurethane and the polyvinyl chloride resin, and the polylactic acid-based polyurethane can play a better toughening role, so that the tensile strength and the elongation at break of the PVC film material are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of polyvinyl chloride, and specifically to a high-strength biodegradable PVC composite film and its preparation process. Background Art

[0002] Polyvinyl chloride has advantages such as good mechanical properties, flame retardancy, water and corrosion resistance, and acid and alkali resistance. It can be made into films, pipes, plastic alloys, etc., and is widely used in fields such as construction, agriculture, and industry. However, as a petroleum-based plastic, polyvinyl chloride is difficult to biodegrade and causes relatively large pollution. Moreover, the mechanical strength of polyvinyl chloride and its film materials is not good, which limits its actual application fields. By compounding polyvinyl chloride with starch, polylactic acid, etc., biodegradable materials with excellent properties can be obtained. The literature "Synthesis and Biodegradability of Polyvinyl Chloride Grafted with Polylactic Acid" reported that graft modification of polyvinyl chloride with polylactic acid endows the polyvinyl chloride material with good biodegradability. However, this literature does not solve the problem of the poor mechanical properties of polyvinyl chloride and its film materials.

[0003] Polyurethane is a high-molecular polymer with high toughness and large mechanical strength, and is widely used in the toughening modification of materials such as polyvinyl chloride, polypropylene, and epoxy resin. By compounding polyurethane with polyvinyl chloride, plastic alloy materials with better properties can be obtained. However, polyurethane and polyvinyl chloride are an incompatible system, resulting in the difficulty for polyurethane to effectively play the role of toughening and strengthening. Summary of the Invention

[0004] The present invention solves the problem that the PVC film material does not have biodegradable properties, and at the same time improves the mechanical properties of the film material.

[0005] Technical Solution: A high-strength biodegradable PVC composite film and its preparation process, including 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: Add polyvinyl chloride resin, polylactic acid-based polyurethane, polylactic acid grafted polyvinyl chloride, plasticizer, heat stabilizer, and lubricant into a mixer for mixing, and then extrude in a single-screw extruder and blow mold in a blow molding machine to obtain a high-strength biodegradable PVC composite film.

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

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

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

[0010] Further, 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).

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

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

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

[0014] Further, the preparation process of the polylactic acid-grafted polyvinyl chloride is as follows: adding cyclohexanone and 200-300 parts by weight of polylactic acid diol into a reaction vessel equipped with a condenser reflux tube, heating and stirring to dissolve, then adding 3-4.5 parts by weight of elemental sodium, heating to 150-155 °C in a nitrogen atmosphere, reacting for 6-8 h, then dropping the solution into a cyclohexanone solution containing 100 parts by weight of polyvinyl chloride resin, reacting at 120-140 °C in a nitrogen atmosphere for 2-8 h, cooling, pouring the solution into ethanol for precipitation, filtering, extracting the product in a Soxhlet extractor with toluene, and drying to obtain the polylactic acid-grafted polyvinyl chloride.

[0015] The beneficial technical effects of the present invention: Using polylactic acid diol, isocyanate monomer, etc. as raw materials, the prepared polylactic acid-based polyurethane is then blended with polylactic acid-grafted polyvinyl chloride, heat stabilizer, polyvinyl chloride resin, etc., and blown into a film to obtain a high-strength biodegradable PVC composite film. The main chain of the polylactic acid-based polyurethane contains a biodegradable polylactic acid molecular chain, and the side chain of the polylactic acid-grafted polyvinyl chloride contains a biodegradable polylactic acid molecular chain, endowing the PVC composite material with excellent biodegradable properties.

[0016] The main chain of the polylactic acid-based polyurethane in this aspect contains a polylactic acid molecular chain, and the side chain of the polylactic acid-grafted polyvinyl chloride contains a polylactic acid molecular chain, resulting in similar solubility between the two. The main chain of the polylactic acid-grafted polyvinyl chloride is a polyvinyl chloride molecular chain, which has good compatibility with the polyvinyl chloride resin. Therefore, the polylactic acid-grafted polyvinyl chloride can be used as a compatibilizer to improve the compatibility between the polylactic acid-based polyurethane and the polyvinyl chloride resin. The polylactic acid-based polyurethane can play a better toughening role, significantly improving the tensile strength and elongation at break of the PVC film material. Detailed implementation mode

[0017] Combined with the detailed implementation mode below, the present invention will be further described. It should be noted that on the premise of no conflict, the following-described embodiments or technical features can be combined arbitrarily to form new embodiments.

[0018] The following polyvinyl chloride resin, with the brand SG-5, is purchased from Jinan Xiangfeng Weiye Chemical Co., Ltd. The polylactic acid diol, with an average molecular weight of 2000, is purchased from Hubei Shuaiyanligao Biopharmaceutical Co., Ltd. The polyethylene wax, with the model PE WAX P208, is 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 condensing reflux tube. After heating and stirring to dissolve, add 1.2 g of elemental sodium. Under a nitrogen atmosphere, heat to 150 °C and carry out a condensing reflux reaction for 7 h. Then, drop the solution into a 150 mL 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, the product is subjected to Soxhlet extraction with toluene in a Soxhlet extractor and dried 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-diisocyanate, and 0.07 mmol of dibutyltin dilaurate to the reaction vessel. Under a nitrogen atmosphere, carry out a prepolymerization reaction at 75 °C for 2.5 h. Then, add 135 mmol of the chain extender 1,4-butanediol and continue the reaction for 60 min. After cooling, discharge the product to obtain the polylactic acid-based polyurethane.

[0022] (3) Add 950 g of polyvinyl chloride resin, 50 g of polylactic acid-based polyurethane, 3 g of polylactic acid-grafted polyvinyl chloride, 100 g of plasticizer dioctyl phthalate, 9 g of tribasic lead sulfate, 21 g of dibasic lead phosphite, 10 g of polyethylene wax, and 7 g of calcium stearate into a mixer for mixing, and then extrude in a single-screw extruder. The temperatures of zones 1 - 6 are 100 °C, 150 °C, 165 °C, 175 °C, 185 °C, and the screw speed is 80 r / min; perform blow molding with a blow molding machine, and the blow-up ratio is 3; 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 into a reaction vessel equipped with a condensing reflux pipe. After heating and stirring to dissolve, add 1.5 g of elemental sodium. Under a nitrogen atmosphere, heat to 150 °C and react for 8 h. Then, drop the solution into 150 mL of a cyclohexanone solution containing 4 g of polyvinyl chloride resin. Under a nitrogen atmosphere, react at 140 °C for 2 h. After cooling, pour the solution into ethanol for precipitation. After filtration, the product is subjected to Soxhlet extraction with toluene in a Soxhlet extractor and dried 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'-diisocyanate, and 0.05 mmol of dibutyltin dilaurate into a reaction vessel. Under 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 to react for 60 min. Cool and discharge to obtain polylactic acid-based polyurethane.

[0026] (3) Add 900 g of polyvinyl chloride resin, 100 g of polylactic acid-based polyurethane, 12 g of polylactic acid-grafted polyvinyl chloride, 75 g of plasticizer dioctyl phthalate, 8 g of tribasic lead sulfate, 18 g of dibasic lead phosphite, 12 g of polyethylene wax, and 8 g of zinc stearate into a mixer for mixing, and then extrude in a single-screw extruder. The temperatures of zones 1 - 6 are 100 °C, 150 °C, 165 °C, 175 °C, 185 °C, and the screw speed is 50 r / min; perform blow molding with a blow molding machine, and the blow-up ratio is 3.5; 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 condenser reflux tube. After heating and stirring to dissolve, add 1.8 g of elemental sodium. Under a nitrogen atmosphere, heat to 150 °C and react for 8 h. Then, drop the solution into 150 mL of a cyclohexanone solution containing 4 g of polyvinyl chloride resin. Under a nitrogen atmosphere, react at 130 °C for 6 h. After cooling, pour the solution into ethanol for precipitation. After filtration, the product is subjected to Soxhlet extraction with toluene in a Soxhlet extractor and dried to obtain polylactic acid grafted polyvinyl chloride.

[0029] (2) Add 40 mmol of dried polypropylene glycol 2000, 60 mmol of polylactic acid diol, 260 mmol of isophorone diisocyanate, and 0.08 mmol of dibutyltin dilaurate to a reaction vessel. Under 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 to react for 40 min. After cooling, discharge the material to obtain polylactic acid-based polyurethane.

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

[0031] Test the biodegradable performance according to the method specified in the standard GB / T 19277.2 - 2013, and the test time is 90 days.

[0032] Table 1 Test of the biodegradation rate of the PVC composite film

[0033]

[0034] After testing, in the PVC composite materials of Examples 1 - 3, polylactic acid-based polyurethane is added, and its main chain contains biodegradable polylactic acid molecular chains. The side chains of the added polylactic acid grafted polyvinyl chloride contain biodegradable polylactic acid molecular chains, endowing the PVC composite materials with excellent biodegradable performance. The 90-day biodegradation rate reaches 11.5 - 18.6.

[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) Add 950 g of polyvinyl chloride resin, 100 g of dioctyl phthalate plasticizer, 9 g of tribasic lead sulfate, 21 g of dibasic lead phosphite, 10 g of polyethylene wax, and 7 g of calcium stearate to a mixer for mixing, and then extrude in a single-screw extruder. The temperatures of zones 1-6 are 100 °C, 150 °C, 165 °C, 175 °C, 185 °C, and the screw speed is 80 r / min; perform blow molding with a blow molding machine, and the blow-up ratio is 3; 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) Add 950 g of polyvinyl chloride resin, 50 g of polylactic acid-based polyurethane, 100 g of dioctyl phthalate plasticizer, 9 g of tribasic lead sulfate, 21 g of dibasic lead phosphite, 10 g of polyethylene wax, and 7 g of calcium stearate to a mixer for mixing, and then extrude in a single-screw extruder. The temperatures of zones 1-6 are 100 °C, 150 °C, 165 °C, 175 °C, 185 °C, and the screw speed is 80 r / min; perform blow molding with a blow molding machine, and the blow-up ratio is 3; obtain a PVC composite film.

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

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

[0041] (2) Add 950 g of polyvinyl chloride resin, 50 g of polyurethane, 3 g of polylactic acid-grafted polyvinyl chloride, 100 g of dioctyl phthalate plasticizer, 9 g of tribasic lead sulfate, 21 g of dibasic lead phosphite, 10 g of polyethylene wax, and 7 g of calcium stearate to a mixer for mixing, and then extrude in a single-screw extruder. The temperatures of zones 1-6 are 100 °C, 150 °C, 165 °C, 175 °C, 185 °C, and the screw speed is 80 r / min; perform blow molding with a blow molding machine, and the blow-up ratio is 3; obtain a PVC composite film.

[0042] Test the tensile properties of the PVC composite film according to the method specified in the standard of GB / T 1040.3-2006.

[0043] Table 2 Tensile Property Test of Composite Film

[0044]

[0045] After testing, the tensile strength in the transverse and longitudinal directions and the elongation at break of the PVC film material of Comparative Example 1 are low, and the mechanical properties are poor.

[0046] The PVC film material of Comparative Example 2 is added with polylactic acid-based polyurethane, and 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 has increased, the tensile strength has decreased significantly.

[0047] The PVC film materials of Examples 1-3 are added with polylactic acid-based polyurethane and polylactic acid-grafted polyvinyl chloride. The main chain of the polylactic acid-based polyurethane contains polylactic acid molecular chains, and the side chain of the polylactic acid-grafted polyvinyl chloride contains polylactic acid molecular chains, resulting in similar solubility between the two. And the main chain of the polylactic acid-grafted polyvinyl chloride is a polyvinyl chloride molecular chain, which has good compatibility with polyvinyl chloride resin, so that the polylactic acid-grafted polyvinyl chloride can act as a compatibilizer to improve the compatibility between the polylactic acid-based polyurethane and the polyvinyl chloride resin. The polylactic acid-based polyurethane can play a better toughening role, significantly improving the tensile strength and elongation at break of the PVC film material.

[0048] When preparing polyurethane in Comparative Example 3, polylactic acid diol was not added, resulting in the main chain of the molecule not containing polylactic acid molecular chains. The polylactic acid-grafted polyvinyl chloride cannot act as a compatibilizer and cannot improve the compatibility between the polylactic acid-based polyurethane and the polyvinyl chloride resin. The toughening of the polyurethane is poor, and the tensile strength and elongation at break of the PVC film material are low.

[0049] The above-mentioned implementation manners are only the preferred implementation manners of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art on the basis of the present invention belong to the scope of protection required 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 comprises: adding dry polyether polyol, polylactic acid diol, isocyanate monomer and dibutyltin dilaurate into a reaction container, performing a prepolymerization reaction in a nitrogen atmosphere, then adding a chain extender, continuing the reaction, cooling and discharging the material to obtain the polylactic acid-based polyurethane.

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 temperature is 70-80°C, the reaction time is 2.5-3h, and the continued reaction time is 40-60min.

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. The high-strength biodegradable PVC composite film according to claim 1, characterized in that: The preparation process of the polylactic acid grafted polyvinyl chloride is as follows: cyclohexanone and 200-300 parts by weight of polylactic acid diol are added to a reaction container equipped with a condenser reflux tube, 3-4.5 parts by weight of elemental sodium are added after heating and stirring to dissolve, the mixture is heated to 150-155° C. in a nitrogen atmosphere, reacted for 6-8 hours, and then the solution is dripped into a cyclohexanone solution containing 100 parts by weight of polyvinyl chloride resin, reacted at 120-140° C. in a nitrogen atmosphere for 2-8 hours, the solution is poured into ethanol for precipitation after cooling, the product is filtered, extracted with toluene in a Soxhlet extractor, and dried to obtain the polylactic acid grafted polyvinyl chloride.

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

10. The process for preparing the high-strength biodegradable PVC composite film according to claim 9, characterized in that: The temperature of zones 1-6 of the single-screw extruder is 100-185° C., the screw speed is 50-80 r / min, and the blow ratio during blow molding is 3-3.5.

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