A carbon dioxide-based polycarbonate modified PVC pipe and its preparation method

Abstract

The present invention belongs to the field of plastic technology, and provides a carbon dioxide-based polycarbonate modified PVC pipe and a preparation method thereof. By using a carbon dioxide-based polycarbonate with a specific molecular weight and modified nano-montmorillonite, a synergistic effect is exerted to 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 property of the PVC pipe, reduce the use of a variety of functional additives, and reduce the cost. At the same time, the carbon dioxide-based polycarbonate is an environmentally friendly polymer resin with good mechanical properties and biodegradability, and its use promotes the resource utilization of carbon dioxide.

Description

Technical Field

[0001] The present 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] Polyvinyl chloride (PVC), as one of the five general-purpose plastics, has good mechanical properties, flame retardancy, electrical insulation properties, chemical corrosion resistance, light weight, and low cost. These advantages enable PVC plastic products to be widely used in various fields such as construction, power cables, automobiles, water supply and drainage, and agricultural irrigation. However, since the structural unit of the PVC molecular chain is a vinyl chloride unit, it has deficiencies in terms of heat resistance, impact resistance, thermal expansion and contraction resistance, processability, etc., which limit 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, being easily broken by impact, local cracking, and poor aging resistance, which restricts the further popularization of PVC pipes. Generally, functional additives such as heat stabilizers, impact modifiers, fillers, plasticizers, and processing modifiers are added to improve the heat resistance, impact resistance, thermal expansion and contraction resistance, processing performance, etc. of PVC pipes. The more types of functional additives, the more likely it is to cause insufficient compatibility of the components of the PVC composition, thus causing problems in terms of processing performance and aging resistance; on the other hand, the differences in thermodynamics, kinetics, etc. between the functional additives and the PVC resin are likely to exacerbate phenomena such as excessive stress, uneven distribution, and inconsistent thermal expansion and contraction performance in the PVC composition, thereby exacerbating many problems such as high brittleness, being easily broken by impact, local cracking, and poor aging resistance of PVC pipes. At the same time, the increase in the types of functional additives also leads to an increase in cost.

[0003] With the enhancement of environmental protection awareness, using degradable raw materials to promote the degradation of plastic products has gradually become a hot topic and trend in production research. Polycarbonate based on carbon dioxide synthesized using carbon dioxide as a raw material has unique advantages in this regard. On the one hand, it realizes the resource utilization of carbon dioxide by using carbon dioxide as a raw material. On the other hand, as an environmentally friendly polymer resin, polycarbonate based on carbon dioxide has excellent mechanical properties and heat resistance. For example, Chinese Patent No. CN111012954A discloses a PVC composition for an antibacterial hydrophilic catheter and its preparation method, in which a low molecular weight polycarbonate based on carbon dioxide and a polyester plasticizer are mixed as a compound plasticizer for the polyvinyl chloride composition. The content of carbonate linkages in the polycarbonate based on carbon dioxide polymer is 92-95%, its molecular weight measured by GPC is 31,000-35,000, and the molecular weight distribution is 10-12; Chinese Patent No. CN108794915A discloses a steel wire mesh-reinforced PVC transparent hose composition, its preparation process and application, using a low molecular weight polycarbonate based on carbon dioxide as a plasticizer and sharing it with two plasticizers, namely diethylene glycol monobutyl sebacate and epoxy polyanhydride diethylene glycol ester. The content of carbonate linkages in the low molecular weight polycarbonate based on carbon dioxide polymer is 92% - 95%, the molecular weight is 31,000 - 35,000, the molecular weight distribution is 10 - 12, and the viscosity is 6800 cps - 7000 cps. Through the hydrogen bond action formed between the relatively large density of carbonyl functional groups on the polycarbonate plasticizer molecular chain and some hydroxyl groups on the two diethylene glycol type plasticizer molecular chains, the oil extraction resistance of the transparent hose polyvinyl chloride composition can be greatly improved. There has been no research attempt to use polycarbonate based on carbon dioxide as a blend resin for 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 object of the present invention is to provide a polycarbonate based on carbon dioxide modified PVC pipe, which exerts a synergistic effect through a polycarbonate based on carbon dioxide with a specific molecular weight and modified nano-montmorillonite to improve the compatibility of PVC resin, polycarbonate based on carbon dioxide and inorganic fillers, 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 a variety of functional additives, reduce the cost. At the same time, polycarbonate based on carbon dioxide 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 fields such as agricultural water supply and drainage and irrigation.

[0005] The object of the present invention is achieved by the following technical solutions:

[0006] A carbon dioxide-based polycarbonate modified PVC pipe, comprising 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 compatibilizer, 15-45 parts by weight of modified nano-montmorillonite, 3-10 parts by weight of plasticizer, 1-5 parts by weight of lubricant, and 1-5 parts by weight of stabilizer; the modified nano-montmorillonite is a modified filler with a core-shell structure, which is formed by intercalating nano-montmorillonite with acrylic hard monomers, long-chain alkyl acrylates, quaternary ammonium salt acrylates, and low molecular weight carbon dioxide-based polycarbonate, and then in-situ polymerizing and wrapping.

[0007] Preferably, the high molecular weight carbon dioxide-based polycarbonate has a molecular weight of 50,000-90,000.

[0008] Preferably, the low molecular weight carbon dioxide-based polycarbonate has a molecular weight of 20,000-40,000.

[0009] Preferably, the acrylic hard monomers include one or more of methyl methacrylate, methyl acrylate, ethyl acrylate, ethyl methacrylate, butyl methacrylate, and styrene.

[0010] Preferably, the long-chain alkyl acrylates include one or more of isooctyl acrylate, lauryl acrylate, cetyl acrylate, and stearyl acrylate.

[0011] Preferably, the quaternary ammonium salt acrylates include one or more of methacryloyloxyethyl trimethyl ammonium chloride, acryloyloxyethyl trimethyl ammonium chloride, acryloyloxypropyl trimethyl ammonium chloride, and methacryloyloxypropyl trimethyl ammonium chloride.

[0012] Preferably, the mass ratio of the acrylic hard monomers, long-chain alkyl acrylates, quaternary ammonium salt acrylates, and low molecular weight carbon dioxide-based polycarbonate is 1:3-12:1.5-5:0.5-2.

[0013] Preferably, the mass ratio of the acrylic hard monomers, long-chain alkyl acrylates, quaternary ammonium salt acrylates, and low molecular weight carbon dioxide-based polycarbonate is 3:14:5:5.

[0014] Preferably, the mass ratio of the total mass of the acrylic hard monomers, long-chain alkyl acrylates, quaternary ammonium salt acrylates, and low molecular weight carbon dioxide-based polycarbonate to the mass of nano-montmorillonite is 0.5-3:1.

[0015] Preferably, the mass ratio of the total mass of the acrylic hard monomers, long-chain alkyl acrylates, quaternary ammonium salt acrylates, and low molecular weight carbon dioxide-based polycarbonate to the mass of nano-montmorillonite is 27:50.

[0016] Preferably, the preparation method of the modified nano-montmorillonite comprises the following steps:

[0017] Step 1: Disperse the nano-montmorillonite in acetone, add quaternary ammonium salt acrylate, and stir for 1 - 3 h to cause ion exchange between the quaternary ammonium salt acrylate and the cations between the montmorillonite layers, insert into the nano-montmorillonite layers, and expand the layer spacing;

[0018] Step 2: Add acrylic acid-based hard monomers, long-chain alkyl acrylates, and low molecular weight carbon dioxide-based polycarbonate to the solution obtained in Step 1, and continue stirring for 1 - 3 h to insert the acrylic acid-based hard monomers, long-chain alkyl acrylates, and low molecular weight carbon dioxide-based polycarbonate into the nano-montmorillonite layers and further expand the layer spacing;

[0019] Step 3: Under stirring conditions, heat the solution obtained in Step 2 to 30 - 35 °C, dropwise add the initiator solution, and cause in-situ polymerization of the acrylic acid-based hard monomers, long-chain alkyl acrylates, and quaternary ammonium salt acrylate 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.

[0020] Preferably, the initiator is a redox initiator.

[0021] 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.

[0022] Preferably, the plasticizer is one or more of polyester plasticizer, DOP, DOS, DBP, and DOTP.

[0023] A preparation method of a carbon dioxide-based polycarbonate modified PVC pipe comprises the following reaction steps:

[0024] Step A: Stir and mix the raw material components of the modified PVC pipe at 100 - 120 °C for 15 - 25 min to obtain a mixed material A;

[0025] Step B: Stir and cool the mixed material A to 25 - 50 °C to obtain a mixed material B;

[0026] Step C: Add the mixed material B to a conical twin-screw extrusion device for extrusion, plasticization, and molding,

[0027] to obtain a carbon dioxide-based polycarbonate modified PVC pipe.

[0028] Beneficial effects:

[0029] 1) Using quaternary ammonium salt acrylate as an intercalating agent, the layer spacing of nano-montmorillonite is expanded through ion exchange. Then, acrylate hard monomer, long-chain alkyl acrylate, and low molecular weight carbon dioxide-based polycarbonate are added to further expand the layer spacing of nano-montmorillonite. In the presence of low molecular weight carbon dioxide-based polycarbonate, in-situ polymerization of quaternary ammonium salt acrylate, acrylate hard monomer, and long-chain alkyl acrylate occurs to conduct in-situ polymerization coating modification on nano-montmorillonite, improving the flexibility and heat resistance of the polymer shell layer on the surface of the modified nano-montmorillonite. At the same time, the compatibility between the modified nano-montmorillonite and components such as PVC resin and high molecular weight carbon dioxide-based polycarbonate is improved, thereby enhancing the heat resistance, impact resistance, thermal expansion and contraction resistance, and antibacterial property of PVC pipes.

[0030] 2) Modifying montmorillonite with low molecular weight carbon dioxide-based polycarbonate and directly blending and modifying components such as high molecular weight carbon dioxide-based polycarbonate and PVC resin. Through their synergistic effect, the fluidity and structural similarity of low molecular weight carbon dioxide-based polycarbonate can be utilized 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 enhancing the strengthening and toughening effect, heat resistance, and thermal expansion and contraction resistance of the modified nano-montmorillonite. At the same time, the heat resistance and flexibility of high molecular weight carbon dioxide-based polycarbonate itself are utilized to improve the heat resistance, impact resistance, and thermal expansion and contraction resistance of PVC pipes. Detailed implementation mode

[0031] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0032] The present invention will be further explained and described below in conjunction with specific implementation modes.

[0033] Preparation Example 1

[0034] A preparation method of modified nano-montmorillonite includes the following steps:

[0035] 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 h to conduct ion exchange between the methacryloyloxyethyl trimethyl ammonium chloride monomer and the cations between the montmorillonite layers, insert into the nano-montmorillonite layer space, and expand the nano-montmorillonite layer spacing;

[0036] 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 on carbon dioxide to the solution obtained in Step 1, and continue stirring for 2 h to insert methyl methacrylate, isooctyl acrylate, lauryl acrylate, and polycarbonate based on carbon dioxide into the interlayers of the nano-montmorillonite, further expanding the layer spacing.

[0037] Step 3: Under stirring conditions, heat the solution obtained 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 on carbon dioxide, to obtain a modified nano-montmorillonite with nano-montmorillonite as the core and polyacrylate / polycarbonate based on carbon dioxide polymer as the shell.

[0038] The polycarbonate based on carbon dioxide is QPAC 25 with a molecular weight of 25,000.

[0039] Comparative Preparation Example 1

[0040] A method for preparing a modified nano-montmorillonite, which prepares modified nano-montmorillonite nanoparticles according to the method of Preparation Example 1, and the only difference is that the polycarbonate based on carbon dioxide is replaced by lauryl acrylate.

[0041] Comparative Preparation Example 2

[0042] A method for preparing a modified nano-montmorillonite, which prepares modified nano-montmorillonite nanoparticles according to the method of Preparation Example 1, and the only difference is that isooctyl acrylate and lauryl acrylate are replaced by methyl methacrylate.

[0043] Comparative Preparation Example 3

[0044] A method for preparing a modified nano-montmorillonite, which prepares modified nano-montmorillonite nanoparticles according to the method of Preparation Example 1, and the only difference is that the methacryloyloxyethyl trimethyl ammonium chloride monomer is replaced by lauryl acrylate.

[0045] Comparative Preparation Example 4

[0046] A method for preparing a modified nano-montmorillonite, which prepares modified nano-montmorillonite nanoparticles according to the method of Preparation Example 1, and the only difference is that the polycarbonate based on carbon dioxide being QPAC 25 is replaced by the polycarbonate based on carbon dioxide being QPAC80.

[0047] Example 1

[0048] A carbon dioxide-based polycarbonate modified PVC pipe, comprising 100 parts by weight of PVC resin, 15 parts by weight of carbon dioxide-based polycarbonate, 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 carbon dioxide-based polycarbonate is QPAC 80 with a molecular weight of 80,000.

[0049] A preparation method of a carbon dioxide-based polycarbonate modified PVC pipe, comprising the following reaction steps:

[0050] Step A: Stir and mix the raw material components of the modified PVC pipe at 120 °C for 15 min to obtain a mixed material A;

[0051] Step B: Stir and cool the mixed material A to 30 °C to obtain a mixed material B;

[0052] 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.

[0053] Comparative Example 1

[0054] A carbon dioxide-based polycarbonate modified PVC pipe is prepared by the method of Example 1, and the only difference is that the modified nano-montmorillonite prepared in Preparation Example 1 is replaced with the modified nano-montmorillonite prepared in Comparative Preparation Example 1.

[0055] Comparative Example 2

[0056] A carbon dioxide-based polycarbonate modified PVC pipe is prepared by the method of Example 1, and the only difference is that the modified nano-montmorillonite prepared in Preparation Example 1 is replaced with the modified nano-montmorillonite prepared in Comparative Preparation Example 2.

[0057] Comparative Example 3

[0058] A carbon dioxide-based polycarbonate modified PVC pipe is prepared by the method of Example 1, and the only difference is that the modified nano-montmorillonite prepared in Preparation Example 1 is replaced with the modified nano-montmorillonite prepared in Comparative Preparation Example 3.

[0059] Comparative Example 4

[0060] A carbon dioxide-based polycarbonate modified PVC pipe is prepared by the method of Example 1, and the only difference is that the modified nano-montmorillonite prepared in Preparation Example 1 is replaced with the modified nano-montmorillonite prepared in Comparative Preparation Example 4.

[0061] Comparative Example 5

[0062] A carbon dioxide-based polycarbonate modified PVC pipe was prepared by the method of Example 1. The only difference was that the carbon dioxide-based polycarbonate QPAC 80 was replaced with the carbon dioxide-based polycarbonate QPAC 25.

[0063] 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 rate 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 property was characterized according to GB / T31402-2015.

[0064] Table 1 Properties of Carbon Dioxide-Based Polycarbonate Modified PVC Pipes

[0065]

[0066] 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 in Example 1, acrylic long-chain alkyl ester was used as a modification monomer in the presence of low molecular weight carbon dioxide-based polycarbonate to carry out in-situ polymerization coating modification on 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.

[0067] From the comparison of 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 in Example 1, quaternary ammonium salt acrylate was used as an intercalating agent, which can expand the layer spacing of montmorillonite through ion exchange, enabling the modification monomer and low molecular weight carbon dioxide-based polycarbonate to fully enter the interlayer of montmorillonite, and realizing the coating modification of montmorillonite through in-situ polymerization to form a core-shell structure, improving the modification effect of nano-montmorillonite. At the same time, quaternary ammonium salt acrylate contains quaternary ammonium cation groups, which can cooperate with montmorillonite to improve the antibacterial effect.

[0068] 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 because in Example 1, montmorillonite is modified with low molecular weight carbon dioxide-based polycarbonate, and high molecular weight carbon dioxide-based polycarbonate is directly blended and modified with components such as PVC resin. Through the synergistic effect, the fluidity and structural similarity of the low molecular weight carbon dioxide-based polycarbonate can be utilized to improve the modification effect of the 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 enhancing the strengthening and toughening effect, heat resistance, and thermal expansion and contraction resistance 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 thermal expansion and contraction resistance of the PVC pipe.

[0069] The above embodiments are preferred embodiments of the present invention, but the embodiments 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 principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A carbon dioxide-based polycarbonate modified PVC pipe, characterized in that, It includes 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 compatibilizer, 15 - 45 parts by weight of modified nano - montmorillonite, 3 - 10 parts by weight of plasticizer, 1 - 5 parts by weight of lubricant, and 1 - 5 parts by weight of stabilizer; the modified nano - montmorillonite is a modified filler with a core - shell structure, which is formed by intercalating nano - montmorillonite with acrylic hard monomers, long - chain alkyl acrylates, quaternary ammonium salt acrylates, and low molecular weight carbon dioxide - based polycarbonate, and then in - situ polymerizing and wrapping; the molecular weight of the high molecular weight carbon dioxide - based polycarbonate is 50,000 - 90,000, and the molecular weight of the low molecular weight carbon dioxide - based polycarbonate is 20,000 - 40,000.

2. The carbon dioxide-based polycarbonate modified PVC pipe according to claim 1, wherein The long - chain alkyl acrylate includes one or more of isooctyl acrylate, lauryl acrylate, cetyl acrylate, and stearyl acrylate.

3. 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.

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

5. The carbon dioxide-based polycarbonate modified PVC pipe according to claim 1, characterized in that, The preparation method of the modified nano - montmorillonite includes the following steps: Step 1, disperse nano - montmorillonite in acetone, add quaternary ammonium salt acrylate, and stir for 1 - 3 h to make the quaternary ammonium salt acrylate exchange ions with the cations between the montmorillonite layers, insert into the nano - montmorillonite layers, and expand the layer spacing. Step 2, add acrylic hard monomer, long - chain alkyl acrylate, and low molecular weight carbon dioxide - based polycarbonate to the solution in Step 1, and continue to stir for 1 - 3 h to make the acrylic hard monomer, long - chain alkyl acrylate, and low molecular weight carbon dioxide - based polycarbonate insert into the nano - montmorillonite layers and further expand the layer spacing. Step 3, under stirring conditions, heat the solution in Step 2 to 30 - 35 °C, dropwise add the initiator solution, and make the acrylic hard monomer, long - chain alkyl acrylate, and quaternary ammonium salt acrylate 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.

6. A method for preparing a carbon dioxide-based polycarbonate modified PVC pipe as described in any one of claims 1-5, characterized in that, It includes the following reaction steps: Step A, stir - mix the raw material components of the modified PVC pipe at 100 - 120 °C for 15 - 25 min to obtain a mixed material A. Step B, stir - cool the mixed material A to 25 - 50 °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.

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