Carbon dioxide-based polycarbonate modified PVC (polyvinyl chloride) pipe and preparation method thereof

Abstract

The invention belongs to the technical field of plastics, and provides a carbon dioxide-based polycarbonate modified PVC (polyvinyl chloride) pipe and a preparation method thereof.The carbon dioxide-based polycarbonate and modified nano-montmorillonite with specific molecular weight play a synergistic effect, the compatibility of PVC resin, carbon dioxide-based polycarbonate and inorganic filler is improved, the processability is improved, and the PVC pipe has the advantages of being high in mechanical strength, good in mechanical property and good in mechanical property. Compared with the prior art, the PVC pipe has the advantages that the heat resistance, the impact resistance, the thermal expansion and cold contraction resistance and the antibacterial property of the PVC pipe are improved, the use of various functional aids is reduced, the cost is reduced, meanwhile, the carbon dioxide-based polycarbonate is environment-friendly polymer resin and has good mechanical property and biodegradability, and resource utilization of carbon dioxide is promoted by using the carbon dioxide-based polycarbonate.

Description

Technical Field

[0001] The invention belongs to the technical field of plastics, and particularly relates to a carbon dioxide-based polycarbonate-modified PVC pipe and a preparation method thereof. Background Art

[0002] As one of the five general-purpose plastics, polyvinyl chloride (PVC) has good mechanical properties, flame retardancy, electrical insulation, chemical corrosion resistance, light weight and low cost. These advantages make PVC plastic products widely used in various fields such as construction, power cables, automobiles, water supply and drainage, agricultural irrigation, etc. However, since the structural unit of the PVC molecular chain is a vinyl chloride unit, it has deficiencies in heat resistance, impact resistance, thermal expansion and contraction resistance, and processability, which limits the application of PVC products. For example, in the application of PVC pipes, the PVC molecular chain structure causes it to have defects such as high brittleness, easy to break under impact, local cracking, and poor aging resistance, which limits the further promotion of PVC pipes. Generally, the heat resistance, impact resistance, thermal expansion and contraction resistance, and processability of PVC pipes are improved by adding functional additives such as heat stabilizers, impact modifiers, fillers, plasticizers, and processing modifiers. The more types of functional additives there are, the more likely it is that the compatibility of the components of the PVC composition will be insufficient, thus causing problems in processing performance and aging resistance. On the other hand, the differences between functional additives and PVC resins in thermodynamics, kinetics, etc. will easily aggravate the excessive stress, uneven distribution, inconsistent thermal expansion and contraction properties of the PVC composition, thereby aggravating many problems such as the brittleness of PVC pipes, easy breakage under impact, local cracking, poor aging resistance, etc. At the same time, the increase in the types of functional additives also leads to higher costs.

[0003] With the enhancement of environmental awareness, the use of degradable raw materials to promote the degradation of plastic products has gradually become a hot spot and trend in production research. Carbon dioxide-based polycarbonate synthesized using carbon dioxide as raw material has unique advantages in this regard. On the one hand, it uses carbon dioxide as raw material to realize the resource utilization of carbon dioxide. On the other hand, carbon dioxide-based polycarbonate, as an environmentally friendly polymer resin, has excellent mechanical properties and heat resistance. For example, a Chinese invention patent with publication number CN111012954A discloses a PVC composition for antibacterial hydrophilic urinary catheter and a preparation method thereof, wherein a low molecular weight carbon dioxide-based polycarbonate is mixed with a polyester plasticizer as a composite plasticizer for a polyvinyl chloride composition, wherein the carbonate segment content of the carbon dioxide-based polycarbonate polymer is 92-95%, and the molecular weight thereof is 31,000-35,000 as determined by GPC, and the molecular weight distribution is 10-12; a Chinese invention patent with publication number CN108794915A discloses a steel mesh-reinforced PVC transparent hose composition and a preparation process and application thereof, wherein a low molecular weight carbon dioxide-based polycarbonate is used as a plasticizer, and is used together with two plasticizers, diethylene glycol monobutyl ether sebacate and epoxy polytetrahydrophthalic anhydride diethylene glycol ester, wherein the carbonate segment content of the low molecular weight carbon dioxide-based polycarbonate polymer is 92% to 95%, the molecular weight is 31,000 to 35,000, the molecular weight distribution is 10 to 12, and the viscosity is 6800 cps to 1000 cps. 7000cps, through the high density of carbonyl functional groups on the molecular chain of polycarbonate plasticizer, hydrogen bonding is formed with some hydroxyl groups on the molecular chains of two diethylene glycol plasticizers, which can greatly improve the oil extraction resistance of transparent hose polyvinyl chloride composition. No research has tried to use carbon dioxide-based polycarbonate as a blending resin of PVC resin to improve the mechanical properties, heat resistance and other properties of PVC products. Summary of the invention

[0004] In order to overcome the problems existing in the prior art, the purpose of the present invention is to provide a carbon dioxide-based polycarbonate modified PVC pipe, which uses carbon dioxide-based polycarbonate with a specific molecular weight and modified nano-montmorillonite to play a synergistic role, improve the compatibility of PVC resin, carbon dioxide-based polycarbonate and inorganic filler, improve the processing performance, and at the same time improve the heat resistance, impact resistance, thermal expansion and contraction resistance and antibacterial properties of the PVC pipe, reduce the use of various functional additives, and reduce costs. At the same time, carbon dioxide-based polycarbonate is an environmentally friendly polymer resin with good mechanical properties. Its use promotes the resource utilization of carbon dioxide and can be widely used in agricultural water supply and drainage and irrigation and other fields.

[0005] The objective of the present invention is achieved through the following technical solutions: A carbon dioxide-based polycarbonate-modified PVC pipe comprises 80-120 parts by weight of PVC resin, 10-30 parts by weight of high molecular weight carbon dioxide-based polycarbonate, 3-10 parts by weight of a compatibilizer, 15-45 parts by weight of modified nano-montmorillonite, 3-10 parts by weight of a plasticizer, 1-5 parts by weight of a lubricant, and 1-5 parts by weight of a stabilizer. The modified nano-montmorillonite is a modified filler with a core-shell structure, which is formed by intercalating the nano-montmorillonite with acrylic hard monomers, long-chain alkyl acrylates, quaternary ammonium salt acrylates, and low molecular weight carbon dioxide-based polycarbonate, followed by in-situ polymerization and encapsulation.

[0006] Preferably, the molecular weight of the high molecular weight carbon dioxide-based polycarbonate is 50,000-90,000.

[0007] Preferably, the molecular weight of the low molecular weight carbon dioxide based polycarbonate is 20,000-40,000.

[0008] Preferably, the acrylic hard monomer includes one or more of methyl methacrylate, methyl acrylate, ethyl acrylate, ethyl methacrylate, butyl methacrylate and styrene.

[0009] Preferably, the long-chain alkyl acrylate includes one or more of isooctyl acrylate, lauryl acrylate, hexadecyl acrylate, and octadecyl acrylate.

[0010] Preferably, the quaternary ammonium salt acrylate includes one or more of methacryloyloxyethyl trimethyl ammonium chloride, acryloyloxyethyl trimethyl ammonium chloride, acryloyloxypropyl trimethyl ammonium chloride, and methacryloyloxypropyl trimethyl ammonium chloride.

[0011] Preferably, the mass ratio of the acrylic hard monomer, the long-chain alkyl acrylate, the quaternary ammonium salt acrylate, and the low molecular weight carbon dioxide-based polycarbonate is 1:3-12:1.5-5:0.5-2.

[0012] Preferably, the mass ratio of the acrylic hard monomer, the long-chain alkyl acrylate, the quaternary ammonium salt acrylate, and the low molecular weight carbon dioxide-based polycarbonate is 3:14:5:5.

[0013] Preferably, the mass ratio of the total mass of the acrylic hard monomer, the long-chain alkyl acrylate, the quaternary ammonium acrylate, and the low molecular weight carbon dioxide-based polycarbonate to the nano-montmorillonite is 0.5-3:1.

[0014] Preferably, the mass ratio of the total mass of the acrylic hard monomer, the long-chain alkyl acrylate, the quaternary ammonium salt acrylate, and the low molecular weight carbon dioxide-based polycarbonate to the nano-montmorillonite is 27:50.

[0015] Preferably, the preparation method of the modified nano-montmorillonite comprises the following steps: Step 1: Disperse the nano-montmorillonite in acetone, add quaternary ammonium acrylate, and stir for 1-3 hours to allow the quaternary ammonium acrylate to exchange ions with cations between montmorillonite layers, insert into the nano-montmorillonite layers, and expand the interlayer distance; Step 2: Add acrylic acid hard monomer, long-chain alkyl acrylate, and low molecular weight carbon dioxide-based polycarbonate to the solution of step 1, and continue stirring for 1-3 hours to allow the acrylic acid hard monomer, long-chain alkyl acrylate, and low molecular weight carbon dioxide-based polycarbonate to be inserted into the nano-montmorillonite layer to further expand the interlayer distance; Step three, under stirring conditions, heating the solution of step two to 30-35° C., adding initiator solution dropwise, allowing acrylic hard monomers, long-chain alkyl acrylates, and quaternary ammonium salt acrylates to undergo in-situ polymerization in the presence of nano-montmorillonite and low molecular weight carbon dioxide-based polycarbonate to obtain modified nano-montmorillonite with nano-montmorillonite as the core and polyacrylate / carbon dioxide-based polycarbonate polymer as the shell.

[0016] Preferably, the initiator is a redox initiator.

[0017] Preferably, the compatibilizer includes one or more of maleic anhydride grafted polyethylene, maleic anhydride grafted polypropylene, maleic anhydride grafted ethylene / vinyl acetate, and maleic anhydride grafted styrene / butadiene / styrene block copolymer.

[0018] Preferably, the plasticizer is one or more of polyester plasticizer, DOP, DOS, DBP, and DOTP.

[0019] A method for preparing a carbon dioxide-based polycarbonate-modified PVC pipe comprises the following reaction steps: Step A, stirring and mixing the raw material components of the modified PVC pipe at 100-120° C. for 15-25 minutes to obtain a mixed material A; Step B, stirring and cooling the mixed material A to 25-50° C. to obtain a mixed material B; Step C, adding the mixed material B into a conical twin-screw extruder for extrusion, plasticization, and molding, The carbon dioxide-based polycarbonate-modified PVC pipe is obtained.

[0020] Beneficial effects: 1) Quaternary ammonium acrylate is used as an intercalating agent to open the interlayer distance of nano-montmorillonite through ion exchange, and then acrylate hard monomer, acrylate long-chain alkyl ester, and low molecular weight carbon dioxide-based polycarbonate are added to further open the interlayer distance of nano-montmorillonite, and in the presence of low molecular weight carbon dioxide-based polycarbonate, quaternary ammonium acrylate, acrylate hard monomer, and acrylate long-chain alkyl ester are in-situ polymerized to perform in-situ polymerization coating modification on the nano-montmorillonite, thereby improving the flexibility and heat resistance of the polymer shell layer on the surface of the modified nano-montmorillonite, and at the same time improving the compatibility of the modified nano-montmorillonite with components such as PVC resin and high molecular weight carbon dioxide-based polycarbonate, thereby improving the heat resistance, impact resistance, thermal expansion and contraction resistance, and antibacterial properties of the PVC pipe.

[0021] 2) Using low molecular weight carbon dioxide based polycarbonate to modify montmorillonite, and directly blending high molecular weight carbon dioxide based polycarbonate with PVC resin and other components for modification, the synergistic effect can be utilized to improve the modification effect of low molecular weight carbon dioxide based polycarbonate on montmorillonite and its compatibility with PVC resin, high molecular weight carbon dioxide based polycarbonate and other components, thereby improving the reinforcing and toughening effect, heat resistance, and resistance to thermal expansion and contraction of the modified nano-montmorillonite. At the same time, the heat resistance and flexibility of the high molecular weight carbon dioxide based polycarbonate itself are utilized to improve the heat resistance, impact resistance and resistance to thermal expansion and contraction of the PVC pipe. DETAILED DESCRIPTION

[0022] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] The present invention is further explained below in conjunction with specific implementation modes.

[0024] Preparation Example 1 A method for preparing modified nano-montmorillonite comprises the following steps: Step 1: Disperse 50 parts by weight of nano-montmorillonite in acetone, add 5 parts by weight of methacryloyloxyethyl trimethyl ammonium chloride monomer, and stir for 1.5 hours to allow the methacryloyloxyethyl trimethyl ammonium chloride monomer to exchange ions with cations between montmorillonite layers and insert into the nano-montmorillonite layers to expand the interlayer distance of the nano-montmorillonite; Step 2: Add 3 parts by weight of methyl methacrylate, 6 parts by weight of isooctyl acrylate, 8 parts by weight of lauryl acrylate, and 5 parts by weight of polycarbonate-based carbon dioxide to the solution in Step 1, and continue stirring for 2 h to insert methyl methacrylate, isooctyl acrylate, lauryl acrylate, and polycarbonate-based carbon dioxide into the interlayer of nano-montmorillonite, further expanding the interlayer spacing; Step 3: Under stirring conditions, heat the solution in Step 2 to 35 °C, and dropwise add a redox initiator solution to cause in-situ polymerization of methyl methacrylate, isooctyl acrylate, lauryl acrylate, and methacryloyloxyethyl trimethyl ammonium chloride monomers in the presence of nano-montmorillonite and polycarbonate-based carbon dioxide to obtain a modified nano-montmorillonite with nano-montmorillonite as the core and polyacrylate / polycarbonate-based carbon dioxide polymer as the shell.

[0025] The polycarbonate-based carbon dioxide is QPAC 25 with a molecular weight of 25,000.

[0026] Comparative Preparation Example 1 A method for preparing a modified nano-montmorillonite, preparing modified nano-montmorillonite nanoparticles according to the method of Preparation Example 1, the only difference being that the polycarbonate-based carbon dioxide is replaced by lauryl acrylate.

[0027] Comparative Preparation Example 2 A method for preparing a modified nano-montmorillonite, preparing modified nano-montmorillonite nanoparticles according to the method of Preparation Example 1, the only difference being that isooctyl acrylate and lauryl acrylate are replaced by methyl methacrylate.

[0028] Comparative Preparation Example 3 A method for preparing a modified nano-montmorillonite, preparing modified nano-montmorillonite nanoparticles according to the method of Preparation Example 1, the only difference being that the methacryloyloxyethyl trimethyl ammonium chloride monomer is replaced by lauryl acrylate.

[0029] Comparative Preparation Example 4 A method for preparing a modified nano-montmorillonite, preparing modified nano-montmorillonite nanoparticles according to the method of Preparation Example 1, the only difference being that the polycarbonate-based carbon dioxide being QPAC 25 is replaced by the polycarbonate-based carbon dioxide being QPAC80.

[0030] Example 1 A polycarbonate-based carbon dioxide modified PVC pipe, comprising 100 parts by weight of PVC resin, 15 parts by weight of polycarbonate-based carbon dioxide, 3 parts by weight of compatibilizer maleic anhydride grafted polyethylene, 20 parts by weight of modified nano-montmorillonite prepared in Preparation Example 1, 6 parts by weight of polyester plasticizer, 2 parts by weight of lubricant polyethylene wax, and 2 parts by weight of calcium-zinc heat stabilizer. The PVC resin is SG-5, and the polycarbonate-based carbon dioxide is QPAC 80 with a molecular weight of 80,000.

[0031] A preparation method of a carbon dioxide-based polycarbonate modified PVC pipe, comprising the following reaction steps: Step A: Stir and mix each raw material component of the modified PVC pipe at 120 °C for 15 min to obtain a mixed material A; Step B: Stir and cool the mixed material A to 30 °C to obtain a mixed material B; Step C: Add the mixed material B into a conical twin-screw extrusion device for extrusion, plasticization, and molding to obtain a carbon dioxide-based polycarbonate modified PVC pipe.

[0032] Comparative Example 1 A carbon dioxide-based polycarbonate modified PVC pipe is prepared by the method of Example 1. The only difference is that the modified nano-montmorillonite prepared in Preparation Example 1 is replaced by the modified nano-montmorillonite prepared in Comparative Preparation Example 1.

[0033] Comparative Example 2 A carbon dioxide-based polycarbonate modified PVC pipe is prepared by the method of Example 1. The only difference is that the modified nano-montmorillonite prepared in Preparation Example 1 is replaced by the modified nano-montmorillonite prepared in Comparative Preparation Example 2.

[0034] Comparative Example 3 A carbon dioxide-based polycarbonate modified PVC pipe is prepared by the method of Example 1. The only difference is that the modified nano-montmorillonite prepared in Preparation Example 1 is replaced by the modified nano-montmorillonite prepared in Comparative Preparation Example 3.

[0035] Comparative Example 4 A carbon dioxide-based polycarbonate modified PVC pipe is prepared by the method of Example 1. The only difference is that the modified nano-montmorillonite prepared in Preparation Example 1 is replaced by the modified nano-montmorillonite prepared in Comparative Preparation Example 4.

[0036] Comparative Example 5 A carbon dioxide-based polycarbonate modified PVC pipe is prepared by the method of Example 1. The only difference is that the carbon dioxide-based polycarbonate QPAC 80 is replaced by the carbon dioxide-based polycarbonate QPAC 25.

[0037] The carbon dioxide-based polycarbonate-modified PVC pipes obtained in Example 1 and Comparative Examples 1-5 were characterized. The Vicat softening temperature was characterized according to GB / T8802-2001, the longitudinal shrinkage was characterized according to GB / T6671-2001, the hydrostatic pressure was characterized according to GB / T6111-2018, the impact strength was characterized according to GB / T1043-2008, and the antibacterial performance was characterized according to GB / T31402-2015.

[0038] Table 1 Properties of CO2-based polycarbonate modified PVC pipes

[0039] From the comparison of Example 1, Comparative Example 1 and Comparative Example 2, it can be seen that Example 1 of the present application has better performance in terms of Vicat softening temperature, longitudinal shrinkage rate, hydrostatic pressure, impact strength, etc. This may be because Example 1 uses long-chain alkyl acrylate as a modifying monomer in the presence of low molecular weight carbon dioxide-based polycarbonate to perform in-situ polymerization and coating modification on the nano-montmorillonite, which can improve the flexibility and heat resistance of the polymer shell layer on the surface of the modified nano-montmorillonite, and at the same time improve the compatibility of the modified nano-montmorillonite with components such as PVC resin and high molecular weight carbon dioxide-based polycarbonate, thereby improving the heat resistance, impact resistance and thermal expansion and contraction resistance of the PVC pipe.

[0040] From the comparison between Example 1 and Comparative Example 3, it can be seen that Example 1 of the present application has better performance in terms of Vicat softening temperature, longitudinal shrinkage rate, hydrostatic pressure, impact strength, antibacterial property, etc. This may be because Example 1 uses quaternary ammonium salt acrylate as an intercalant, which can open the interlayer spacing of montmorillonite through ion exchange, so that the modified monomer and low molecular weight carbon dioxide-based polycarbonate can fully enter the interlayer of montmorillonite, and realize the coating modification of montmorillonite through in-situ polymerization to form a core-shell structure, thereby improving the modification effect of nano-montmorillonite. At the same time, the quaternary ammonium salt acrylate contains a quaternary ammonium cationic group, which can synergize with montmorillonite to improve the antibacterial effect.

[0041] From the comparison of Example 1, Comparative Example 4 and Comparative Example 5, it can be seen that Example 1 of the present application has better performance in terms of Vicat softening temperature, longitudinal shrinkage rate, hydrostatic pressure, impact strength, etc. This may be due to the fact that Example 1 uses low molecular weight carbon dioxide-based polycarbonate to modify montmorillonite, and high molecular weight carbon dioxide-based polycarbonate is directly blended and modified with components such as PVC resin, and the synergistic effect can be used to improve the modification effect of low molecular weight carbon dioxide-based polycarbonate on montmorillonite and its compatibility with components such as PVC resin and high molecular weight carbon dioxide-based polycarbonate, thereby improving the strengthening and toughening effect, heat resistance, and resistance to thermal expansion and contraction of the modified nano-montmorillonite. At the same time, the heat resistance and flexibility of the high molecular weight carbon dioxide-based polycarbonate itself are used to improve the heat resistance, impact resistance and resistance to thermal expansion and contraction of the PVC pipe.

[0042] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention shall be equivalent replacement methods and shall be included in the protection scope of the present invention.

Claims

1. A carbon dioxide-based polycarbonate-modified PVC pipe, characterized in that: The invention comprises 80-120 parts by weight of PVC resin, 10-30 parts by weight of high molecular weight carbon dioxide-based polycarbonate, 3-10 parts by weight of a compatibilizer, 15-45 parts by weight of a modified nano-montmorillonite, 3-10 parts by weight of a plasticizer, 1-5 parts by weight of a lubricant and 1-5 parts by weight of a stabilizer. The modified nano-montmorillonite is a modified filler with a core-shell structure, which is formed by intercalating the nano-montmorillonite with acrylic hard monomers, long-chain alkyl acrylates, quaternary ammonium salt acrylates and low molecular weight carbon dioxide-based polycarbonate, and then encapsulating the nano-montmorillonite through in-situ polymerization.

2. The carbon dioxide-based polycarbonate-modified PVC pipe according to claim 1, characterized in that: The molecular weight of the high molecular weight carbon dioxide based polycarbonate is 50,000-90,000.

3. The carbon dioxide-based polycarbonate-modified PVC pipe according to claim 1, characterized in that: The molecular weight of the low molecular weight carbon dioxide based polycarbonate is 20,000-40,000.

4. The carbon dioxide-based polycarbonate-modified PVC pipe according to claim 1, characterized in that: The long-chain alkyl acrylate includes one or more of isooctyl acrylate, lauryl acrylate, hexadecyl acrylate, and octadecyl acrylate.

5. The carbon dioxide-based polycarbonate-modified PVC pipe according to claim 1, characterized in that: The quaternary ammonium salt acrylate includes one or more of methacryloyloxyethyl trimethyl ammonium chloride, acryloyloxyethyl trimethyl ammonium chloride, acryloyloxypropyl trimethyl ammonium chloride, and methacryloyloxypropyl trimethyl ammonium chloride.

6. The carbon dioxide-based polycarbonate-modified PVC pipe according to claim 1, characterized in that: The mass ratio of the acrylic hard monomer, the long-chain alkyl acrylate, the quaternary ammonium salt acrylate and the low molecular weight carbon dioxide-based polycarbonate is 1:3-12:1.5-5:0.5-2.

7. The carbon dioxide-based polycarbonate-modified PVC pipe according to claim 1, characterized in that: The preparation method of the modified nano-montmorillonite comprises the following steps: Step 1: Disperse the nano-montmorillonite in acetone, add quaternary ammonium acrylate, and stir for 1-3 hours to allow the quaternary ammonium acrylate to exchange ions with cations between montmorillonite layers, insert into the nano-montmorillonite layers, and expand the interlayer distance; Step 2: Add acrylic acid hard monomer, long-chain alkyl acrylate, and low molecular weight carbon dioxide-based polycarbonate to the solution of step 1, and continue stirring for 1-3 hours to allow the acrylic acid hard monomer, long-chain alkyl acrylate, and low molecular weight carbon dioxide-based polycarbonate to be inserted into the nano-montmorillonite layer to further expand the interlayer distance; Step three, under stirring conditions, heating the solution of step two to 30-35° C., adding initiator solution dropwise, allowing acrylic hard monomers, long-chain alkyl acrylates, and quaternary ammonium salt acrylates to undergo in-situ polymerization in the presence of nano-montmorillonite and low molecular weight carbon dioxide-based polycarbonate to obtain modified nano-montmorillonite with nano-montmorillonite as the core and polyacrylate / carbon dioxide-based polycarbonate polymer as the shell.

8. A method for preparing a carbon dioxide-based polycarbonate-modified PVC pipe as claimed in any one of claims 1 to 7, characterized in that: The process comprises the following reaction steps: Step A, stirring and mixing the raw material components of the modified PVC pipe at 100-120° C. for 15-25 minutes to obtain a mixed material A; Step B, stirring and cooling the mixed material A to 25-50° C. to obtain a mixed material B; Step C, adding the mixed material B into a conical twin-screw extruder for extrusion, plasticization, and molding to obtain a carbon dioxide-based polycarbonate-modified PVC pipe.

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