PVC foaming regulator and preparation process thereof
By optimizing the long-chain structure of cyclodextrin derivatives through the cross-linking reaction of MMA and BA, the problems of high synthesis difficulty and high viscosity caused by the excessively large molecular weight of acrylate foaming regulators were solved, and efficient and uniform foaming and strength improvement of PVC foam materials were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANDONG HETIANXIA NEW MATERIAL CO LTD
- Filing Date
- 2025-04-14
- Publication Date
- 2026-05-12
AI Technical Summary
Existing acrylate foaming regulators have excessively large molecular weights, leading to high synthesis difficulty and cost, and excessively high viscosity, which affects the control of the foaming process. How to improve the foaming effect of PVC within a certain molecular weight range is an urgent technical problem to be solved.
MMA and BA are used as mixed monomers to form a cross-linking transition layer through direct mixing reaction. Combined with cyclodextrin derivatives and modified polyethylene glycol, a long-chain molecular slip ring structure is formed, which optimizes the bubble pore structure of the foaming agent and improves the strength and uniformity of PVC foam materials.
It achieves finer and more uniform bubble structure, improves the strength and processing efficiency of PVC foam materials, prevents bubble coalescence, and enhances foaming effect and product quality.
Smart Images
Figure CN119978514B_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of PVC foaming agent technology, and in particular relates to a PVC foaming regulator and its preparation process. Background Technology
[0002] PVC foam products are waterproof, flame retardant, acid and alkali resistant, insect resistant, lightweight, heat-insulating, sound-insulating, and shock-absorbing. They are ideal substitutes for wood, aluminum, and composite panels, and are widely used in interior decoration panels, building exterior wall panels, interior decoration panels, offices, residences, public buildings, and many other fields, and have very important application value.
[0003] With the development of PVC material technology, people have increasingly higher requirements for the performance of PVC foamed products. However, problems such as poor impact resistance, long processing cycles, and low processing efficiency have emerged in the application of PVC foamed products. Therefore, it is necessary to improve the foaming performance of foamed products to solve these problems.
[0004] In PVC foaming processes, acrylate foaming regulators improve the processing performance and plasticizing properties of PVC, adjust the pore structure of bubbles generated during foaming, and increase the strength of the PVC foam melt. This prevents the coalescence of numerous bubbles, greatly contributing to the production of uniformly foamed PVC products. Acrylic foaming regulators are ultra-high molecular weight, multi-layered acrylate polymers. Their chemical composition is obtained through multi-stage emulsion polymerization of acrylate monomers and other monomers. Their preparation and synthesis processes are currently a crucial research topic in PVC foaming technology.
[0005] For example, patent application CN117757129A discloses a PVC foaming regulator and its preparation method. The regulator is obtained by dehydrating and drying a polymer emulsion. The polymer emulsion is a mixture of acrylate compounds, methacrylate compounds, pH adjusters, initiators, etc. The PVC foaming regulator is prepared by copolymerizing multiple compounds, and the intrinsic viscosity of the resulting copolymer is higher than that of the copolymer obtained by a single initiation system.
[0006] For example, patent application CN112940168A discloses a production process for a high-viscosity PVC foaming regulator. By changing the initiation method and adopting a redox compound initiation system, the reaction is accelerated, thereby increasing the reaction rate and increasing the molecular weight of the polymer. Furthermore, by controlling the amount of each raw material component and the reaction conditions, the emulsion polymerization reaction can be carried out at a lower initiation temperature and with less initiator to obtain a copolymer with a larger molecular weight, thus improving the intrinsic viscosity of the PVC foaming regulator.
[0007] For acrylate foaming regulators, molecular weight is a crucial indicator. Increasing the molecular weight of acrylate foaming regulators can significantly improve foam stabilization and reinforcement during the foaming process. However, once the dosage and molecular weight of acrylate foaming regulators reach certain limits, two problems arise: firstly, excessively large molecular weights increase synthesis difficulty and cost; secondly, excessively high molecular weights lead to excessively high viscosity, negatively impacting the control of the foaming process. Therefore, improving the foaming effect of PVC within a certain molecular weight range is a pressing technical problem that needs to be solved. Summary of the Invention
[0008] To address the aforementioned issues and further improve the performance of acrylate foaming regulators, this application provides a PVC foaming regulator and its preparation process.
[0009] This application first provides a preparation process for a PVC foaming regulator, comprising the following steps:
[0010] 1) A pre-emulsion is prepared by blending mixed monomers, emulsifiers, and water; the mixed monomers include MMA and BA;
[0011] 2) Dissolve cyclodextrin derivatives, disaccharides, and modified polyethylene glycol in a solvent, and then add maleimide to react and prepare a precursor solution;
[0012] 3) Take the pre-emulsion for polymerization reaction. When the monomer conversion rate is 70-80%, add the precursor liquid to the reaction system and continue the reaction until the internal temperature drops. Stop the reaction, then freeze to demulsify, dry and pulverize to obtain the product.
[0013] Furthermore, in step 1), the mixed monomers are composed of MMA and BA in a mass ratio of (9-13):1;
[0014] And / or, in step 1), the emulsifier is one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium dodecylaminopropionate, and hexadecyltrimethylammonium bromide;
[0015] And / or, in step 1), the mass of the emulsifier accounts for 3-5 wt% of the mass of the mixed monomers.
[0016] Furthermore, in step 2), the mass ratio of the cyclodextrin derivative, disaccharide, and modified polyethylene glycol is 1:(0.1-0.15):(0.3-0.5).
[0017] And / or, in step 2), the modified polyethylene glycol is one of amino-terminated polyethylene glycol, carboxyl-terminated polyethylene glycol, or hydroxyl-terminated polyethylene glycol;
[0018] And / or, in step 2), the disaccharide is one or more of lactose, trehalose, and maltose.
[0019] Furthermore, in step 3), the volume ratio of the pre-emulsion to the precursor solution is 1:(0.15-0.2).
[0020] Furthermore, in step 2), the cyclodextrin derivative is prepared using the following method:
[0021] S1: Dissolve cyclodextrin and sodium hydroxide in deionized water, then add an ethanol solution of p-toluenesulfonic acid imidazole, and the intermediate product is obtained after the reaction.
[0022] S2: Dissolve the intermediate in DMF, add N-vinylimidazole, react with microwave, and then remove DMF to obtain the final product.
[0023] Furthermore, in step S1, the molar ratio of cyclodextrin to p-toluenesulfonic acid imidazole is 1:(1.2-1.5).
[0024] Furthermore, in step S2, the molar ratio of cyclodextrin to N-vinylimidazole is controlled to be 1:(1.5-2).
[0025] Furthermore, in step 3), 3-aminophenylboronic acid and bis(trifluoromethanesulfonyl)imide are added after the reaction is stopped.
[0026] Furthermore, in step 3), the amount of 3-aminophenylboronic acid added accounts for 2-3% of the mass of the pre-emulsion; the amount of bis(trifluoromethanesulfonyl)imide added accounts for 0.5-1% of the mass of the pre-emulsion.
[0027] This application also provides a PVC foaming regulator, which is prepared using the above-described preparation process.
[0028] Compared with the prior art, this application has the following beneficial effects:
[0029] 1. This application uses MMA and BA as mixed monomers and adopts a direct mixing reaction method to form a cross-linking transition layer between the copolymers of MMA and BA, thereby improving the compatibility of the copolymers and increasing the molecular weight of the reaction products. In the foaming process, it can optimize and adjust the pore structure of the bubbles generated by the decomposition of the foaming agent, improve the strength of the PVC foam material, prevent the large-scale merging of bubbles during the foaming process, and thus obtain a uniform and fine foam structure.
[0030] 2. In this application, a precursor liquid is introduced at an appropriate time point during the monomer polymerization reaction. The cyclodextrin derivative in the precursor liquid forms a long-chain molecular slip ring structure with the modified polyethylene glycol. During the foaming process, the long molecular chains of the precursor liquid wrap around and attach to the molecular chains of PVC and foaming regulator, forming a dynamic elastic network structure to a certain extent. This allows the PVC melt to maintain sufficient fluidity while improving the toughness and strength of the bubble walls, ensuring that the bubbles are well coated. This ensures that the gas generated by the decomposition of the foaming agent can be refined into smaller bubbles, reducing and preventing bubble collapse and merging. Ultimately, this ensures a complete and uniform bubble structure, thereby improving the foaming effect and product quality of PVC. Attached Figure Description
[0031] Figure 1 This is a schematic diagram showing the intrinsic viscosity data of the PVC foaming regulator in Examples 1-3 and Control Groups 1-2 of this application;
[0032] Figure 2 Here is a SEM image of the foam sample from Example 1 of this application;
[0033] Figure 3 Here is a SEM image of the foam sample from Example 2 of this application;
[0034] Figure 4 Here is a SEM image of the foam sample from Example 3 of this application;
[0035] Figure 5 This is a SEM image of the foam sample from control group 1 of this application;
[0036] Figure 6 This is a SEM image of the foam sample from control group 2 of this application;
[0037] Figure 7 This is a schematic diagram of the compressive stress-strain data of foam samples from Examples 1-3 and Control Groups 1-2 of this application;
[0038] Figure 8 The infrared spectra of the cyclodextrin derivative and β-cyclodextrin in Example 2 of this application are shown. Detailed Implementation
[0039] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.
[0040] This application, through extensive experimental research, optimizes monomer types and ratios, employs a mixed polymerization method to improve the compatibility between monomer copolymers, and combines a precursor liquid containing cyclodextrin derivatives, resulting in better foaming performance of the PVC foaming regulator within a certain intrinsic viscosity range. Specifically, this application provides a preparation process for a PVC foaming regulator, including the following steps:
[0041] 1) A pre-emulsion is prepared by blending mixed monomers, emulsifiers, and water; the mixed monomers include MMA and BA;
[0042] 2) Dissolve cyclodextrin derivatives, disaccharides, and modified polyethylene glycol in a solvent, and then add maleimide to react and prepare a precursor solution;
[0043] 3) Take the pre-emulsion for polymerization reaction. When the monomer conversion rate is 70-80%, add the precursor liquid to the reaction system and continue the reaction until the internal temperature drops. Stop the reaction, then freeze to demulsify, dry and pulverize to obtain the product.
[0044] Furthermore, in step 1), the mixed monomers are composed of MMA and BA in a mass ratio of (9-13):1;
[0045] And / or, in step 1), the emulsifier is one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium dodecylaminopropionate, and hexadecyltrimethylammonium bromide;
[0046] And / or, in step 1), the mass of the emulsifier accounts for 3-5 wt% of the mass of the mixed monomers.
[0047] In some specific embodiments, in step 1), the mixed monomers can be composed of MMA and BA in a mass ratio of 9:1, 9.5:1, 10:1, 10.5:1, 11:1, 11.5:1, 12:1, 12.5:1, or 13:1. More preferably, under normal circumstances, when the mixed monomers in step 1) are composed of MMA and BA in a mass ratio of 12.5:1, better experimental results can be obtained.
[0048] In some specific embodiments, the experimental results are generally best when the emulsifier in step 1) is sodium dodecyl sulfate.
[0049] In some specific embodiments, in step 1), the mass of the emulsifier can be 3 wt%, 3.3 wt%, 3.5 wt%, 3.7 wt%, 3.85 wt%, 4 wt%, 4.2 wt%, 4.5 wt%, 4.8 wt%, or 5 wt% of the mixed monomers. Generally, in step 1), a mass of 3.5% of the emulsifier in the mixed monomers yields better experimental results.
[0050] Furthermore, in step 2), the mass ratio of the cyclodextrin derivative, disaccharide, and modified polyethylene glycol is 1:(0.1-0.15):(0.3-0.5).
[0051] And / or, in step 2), the modified polyethylene glycol is one of amino-terminated polyethylene glycol, carboxyl-terminated polyethylene glycol, or hydroxyl-terminated polyethylene glycol;
[0052] And / or, in step 2), the disaccharide is one or more of lactose, trehalose, and maltose.
[0053] Furthermore, in step 3), the volume ratio of the pre-emulsion to the precursor solution is 1:(0.15-0.2).
[0054] In some specific embodiments, in step 2), the mass ratio of cyclodextrin derivative, disaccharide, and modified polyethylene glycol can be 1:0.1:0.3, 1:0.11:0.3, 1:0.12:0.3, 1:0.13:0.3, 1:0.14:0.3, 1:0.15:0.3, 1:0.1:0.35, 1:0.11:0.35, 1:0.12:0.35, 1:0.13:0.35, 1:0.14:0.35, 1:0.15:0.35, 1:0.1:0.4, 1: The following ratios are used: 0.11:0.4, 1:0.12:0.4, 1:0.13:0.4, 1:0.14:0.4, 1:0.15:0.4, 1:0.1:0.45, 1:0.11:0.45, 1:0.12:0.45, 1:0.13:0.45, 1:0.14:0.45, 1:0.15:0.45, 1:0.1:0.5, 1:0.11:0.5, 1:0.12:0.5, 1:0.13:0.5, 1:0.14:0.5, and 1:0.15:0.5. Under normal experimental conditions, in step 2), a mass ratio of cyclodextrin derivative, disaccharide, and modified polyethylene glycol of 1:0.1:0.35 yields the best experimental results.
[0055] In some specific embodiments, under normal circumstances, when the modified polyethylene glycol in step 2) is amino-terminated polyethylene glycol, better experimental results can be obtained.
[0056] In some specific embodiments, under normal circumstances, when the disaccharide in step 2) is composed of lactose and trehalose in a mass ratio of 2:1, better experimental results can be obtained.
[0057] In some specific embodiments, in step 3), the volume ratio of the pre-emulsion to the precursor solution can be 1:0.15, 1:0.155, 1:0.16, 1:0.165, 1:0.17, 1:0.175, 1:0.18, 1:0.185, 1:0.19, 1:0.195, or 1:0.2. Generally, a volume ratio of 1:0.165 for the pre-emulsion to the precursor solution in step 3) yields better experimental results.
[0058] In some specific embodiments, under normal circumstances, when the monomer conversion rate is 75%, a precursor solution is added to the reaction system, which can achieve better experimental results.
[0059] Furthermore, in step 2), the cyclodextrin derivative is prepared using the following method:
[0060] S1: Dissolve cyclodextrin and sodium hydroxide in deionized water, then add an ethanol solution of p-toluenesulfonic acid imidazole, and the intermediate product is obtained after the reaction.
[0061] S2: Dissolve the intermediate in DMF, add N-vinylimidazole, react with microwave, and then remove DMF to obtain the final product.
[0062] Furthermore, in step S1, the molar ratio of cyclodextrin to p-toluenesulfonic acid imidazole is 1:(1.2-1.5).
[0063] Furthermore, in step S2, the molar ratio of cyclodextrin to N-vinylimidazole is controlled to be 1:(1.5-2).
[0064] Furthermore, in step 3), 3-aminophenylboronic acid and bis(trifluoromethanesulfonyl)imide are added after the reaction is stopped.
[0065] Furthermore, in step 3), the amount of 3-aminophenylboronic acid added accounts for 2-3% of the mass of the pre-emulsion; the amount of bis(trifluoromethanesulfonyl)imide added accounts for 0.5-1% of the mass of the pre-emulsion.
[0066] In some specific embodiments, β-cyclodextrin is typically selected as the cyclodextrin, which usually yields better experimental results.
[0067] In some specific embodiments, in step S1, the molar ratio of cyclodextrin to p-toluenesulfonic acid imidazole can be 1:1.2, 1:1.25, 1:1.3, 1:1.35, 1:1.4, 1:1.45, or 1:1.5. Generally, a molar ratio of cyclodextrin to p-toluenesulfonic acid imidazole of 1:1.3 is preferred for better experimental results in step S1.
[0068] In some specific embodiments, in step S2, the molar ratio of cyclodextrin to N-vinylimidazole can be controlled to be 1:1.5, 1:1.55, 1:1.6, 1:1.65, 1:1.7, 1:1.75, 1:1.8, 1:1.85, 1:1.9, 1:1.95, or 1:2. Generally, controlling the molar ratio of cyclodextrin to N-vinylimidazole to be 1:1.55 in step S2 yields better experimental results.
[0069] In some specific embodiments, in step 3), the amount of 3-aminophenylboronic acid added can be 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, or 3% of the preemulsion mass; the amount of bis(trifluoromethanesulfonyl)imide added can be 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, or 1% of the preemulsion mass. Generally, in step 3), a better experimental effect can be obtained when the amount of 3-aminophenylboronic acid added is 2.5% of the preemulsion mass and the amount of bis(trifluoromethanesulfonyl)imide added is 0.85% of the preemulsion mass.
[0070] Example 1
[0071] The preparation process of the PVC foaming regulator in this embodiment includes the following steps:
[0072] 1) Add 300 mL of deionized water, 7.56 g of sodium dodecyl sulfate, and 0.05 g of sodium hydroxide to a 1 L four-necked flask equipped with a thermometer, stirrer, condenser, and constant pressure funnel. Mix well. Then add 200 g of MMA and 16 g of BA and mix to obtain a pre-emulsion. MMA and BA are first washed with a 5% sodium hydroxide solution, then washed with deionized water until neutral, and dried for later use.
[0073] 2) Add 200 mL of anhydrous ethanol to a 500 mL four-necked flask equipped with a thermometer, stirrer, and constant pressure funnel. Then add 20 g of cyclodextrin derivative, 2 g of disaccharide, and 7 g of amino-terminated polyethylene glycol and mix well. Adjust the pH to a slightly alkaline level, then add maleimide and react at 50 °C for 2 h. Then evaporate a portion of the anhydrous ethanol to obtain the precursor solution. The dynamic viscosity of the precursor solution is 70 mPa·s (20 °C). The cyclodextrin derivative is carboxymethyl-β-cyclodextrin. The disaccharide is composed of lactose and trehalose in a mass ratio of 2:1. The average degree of polymerization of the amino-terminated polyethylene glycol is n=13.
[0074] 3) Add 0.2g of potassium persulfate and 0.2g of sodium sulfite to the above pre-emulsion and mix well. Heat to 65°C and carry out polymerization under nitrogen protection. When the monomer conversion rate is 75%, add the precursor liquid to the reaction system (controlling the volume ratio of pre-emulsion to precursor liquid to be 1:0.165). Heat to 75°C and continue the reaction until the internal temperature drops to 50°C. Stop the reaction, then freeze to demulsify, dry and pulverize to obtain PVC foaming regulator.
[0075] Example 2
[0076] The preparation process of the PVC foaming regulator in this embodiment includes the following steps:
[0077] 1) Add 300 mL of deionized water, 7.56 g of sodium dodecyl sulfate, and 0.05 g of sodium hydroxide to a 1 L four-necked flask equipped with a thermometer, stirrer, condenser, and constant pressure funnel. Mix well. Then add 200 g of MMA and 16 g of BA and mix to obtain a pre-emulsion. MMA and BA are first washed with a 5% sodium hydroxide solution, then washed with deionized water until neutral, and dried for later use.
[0078] 2) Add 200 mL of anhydrous ethanol to a 500 mL four-necked flask equipped with a thermometer, stirrer, and constant pressure funnel. Then add 20 g of cyclodextrin derivative, 2 g of disaccharide, and 7 g of amino-terminated polyethylene glycol and mix well. Adjust the pH to a slightly alkaline level, then add maleimide and react at 50 °C for 2 h. Then evaporate a portion of the anhydrous ethanol to obtain the precursor solution. The dynamic viscosity of the precursor solution is 70 mPa·s (20 °C). The disaccharide is composed of lactose and trehalose in a mass ratio of 2:1. The average degree of polymerization of the amino-terminated polyethylene glycol is n=13.
[0079] 3) Add 0.2g of potassium persulfate and 0.2g of sodium sulfite to the above pre-emulsion and mix well. Heat to 65°C and carry out polymerization under nitrogen protection. When the monomer conversion rate is 75%, add the precursor liquid to the reaction system (controlling the volume ratio of pre-emulsion to precursor liquid to be 1:0.165). Heat to 75°C and continue the reaction until the internal temperature drops to 50°C. Stop the reaction, then freeze to demulsify, dry and pulverize to obtain PVC foaming regulator.
[0080] The cyclodextrin derivative in this embodiment was prepared using the following steps:
[0081] S1: Add 200g of deionized water, 25g of cyclodextrin, and 5.5g of sodium hydroxide to a four-necked flask and mix well. Then add an ethanol solution of p-toluenesulfonic acid imidazole (controlling the molar ratio of cyclodextrin to p-toluenesulfonic acid imidazole to be 1:1.3). React at room temperature, distill, wash with deionized water, and dry to obtain the intermediate product.
[0082] S2: Transfer the intermediate product obtained in step S1 to another four-necked flask, add 250 mL of DMF, stir until completely dissolved, then add N-vinylimidazole (controlling the molar ratio of cyclodextrin to N-vinylimidazole to be 1:1.55), microwave reaction under nitrogen protection for 4 h, and distill to remove DMF to obtain the final product.
[0083] Example 3
[0084] The preparation process of the PVC foaming regulator in this embodiment includes the following steps:
[0085] 1) Add 300 mL of deionized water, 7.56 g of sodium dodecyl sulfate, and 0.05 g of sodium hydroxide to a 1 L four-necked flask equipped with a thermometer, stirrer, condenser, and constant pressure funnel. Mix well. Then add 200 g of MMA and 16 g of BA and mix to obtain a pre-emulsion. MMA and BA are first washed with a 5% sodium hydroxide solution, then washed with deionized water until neutral, and dried for later use.
[0086] 2) Add 200 mL of anhydrous ethanol to a 500 mL four-necked flask equipped with a thermometer, stirrer, and constant pressure funnel. Then add 20 g of cyclodextrin derivative, 2 g of disaccharide, and 7 g of amino-terminated polyethylene glycol and mix well. Adjust the pH to a slightly alkaline level, then add maleimide and react at 50 °C for 2 h. Then evaporate a portion of the anhydrous ethanol to obtain the precursor solution. The dynamic viscosity of the precursor solution is 70 mPa·s (20 °C). The disaccharide is composed of lactose and trehalose in a mass ratio of 2:1. The average degree of polymerization of the amino-terminated polyethylene glycol is n=13.
[0087] 3) Add 0.2g of potassium persulfate and 0.2g of sodium sulfite to the above pre-emulsion and mix well. Heat to 65℃ and carry out polymerization under nitrogen protection. When the monomer conversion rate is 75%, add the precursor liquid to the reaction system (control the volume ratio of pre-emulsion to precursor liquid to be 1:0.165). Heat to 75℃ and continue the reaction until the internal temperature drops to 50℃. Stop the reaction. Then add 3-aminophenylboronic acid and bis(trifluoromethanesulfonyl)imide (control the amount of 3-aminophenylboronic acid added to be 2.5% of the mass of pre-emulsion and the amount of bis(trifluoromethanesulfonyl)imide added to be 0.85% of the mass of pre-emulsion). Continue stirring for 30min. Then freeze to break the emulsion, dry and pulverize to obtain PVC foaming regulator.
[0088] The cyclodextrin derivative in this embodiment was prepared using the following steps:
[0089] S1: Add 200g of deionized water, 25g of cyclodextrin, and 5.5g of sodium hydroxide to a four-necked flask and mix well. Then add an ethanol solution of p-toluenesulfonic acid imidazole (controlling the molar ratio of cyclodextrin to p-toluenesulfonic acid imidazole to be 1:1.3). React at room temperature, distill, wash with deionized water, and dry to obtain the intermediate product.
[0090] S2: Transfer the intermediate product obtained in step S1 to another four-necked flask, add 250 mL of DMF, stir until completely dissolved, then add N-vinylimidazole (controlling the molar ratio of cyclodextrin to N-vinylimidazole to be 1:1.55), microwave reaction under nitrogen protection for 4 h, and distill to remove DMF to obtain the final product.
[0091] Control group 1
[0092] The preparation process of the PVC foaming regulator in this control group includes the following steps:
[0093] 1) Add 300 mL of deionized water, 7.56 g of sodium dodecyl sulfate, and 0.05 g of sodium hydroxide to a 1 L four-necked flask equipped with a thermometer, stirrer, condenser, and constant pressure funnel. Mix well. Then add 200 g of MMA and 16 g of BA and mix to obtain a pre-emulsion. MMA and BA are first washed with a 5% sodium hydroxide solution, then washed with deionized water until neutral, and dried for later use.
[0094] 2) Add 0.2g potassium persulfate and 0.2g sodium sulfite to the above pre-emulsion and mix well. Heat to 65°C and carry out polymerization reaction under nitrogen protection. React until the internal temperature drops to 50°C. Then freeze to demulsify, dry and pulverize to obtain PVC foaming regulator.
[0095] Control group 2
[0096] The preparation process of the PVC foaming regulator in this control group includes the following steps:
[0097] 1) Add 300 mL of deionized water, 7.56 g of sodium dodecyl sulfate, and 0.05 g of sodium hydroxide to a 1 L four-necked flask equipped with a thermometer, stirrer, condenser, and constant pressure funnel. Mix well. Then add 200 g of MMA and 16 g of BA and mix to obtain a pre-emulsion. MMA and BA are first washed with a 5% sodium hydroxide solution, then washed with deionized water until neutral, and dried for later use.
[0098] 2) Add 0.2g of potassium persulfate and 0.2g of sodium sulfite to the above pre-emulsion and mix well. Heat to 65°C and carry out polymerization under nitrogen protection. When the monomer conversion rate is 75%, add terminal amino polyethylene glycol to the reaction system (control the volume ratio of pre-emulsion to terminal amino polyethylene glycol to be 1:0.165, and the average degree of polymerization of terminal amino polyethylene glycol n=13). Heat to 75°C and continue the reaction until the internal temperature drops to 50°C. Stop the reaction, then freeze to break the emulsion, dry and pulverize to obtain PVC foaming regulator.
[0099] Performance testing
[0100] 1. Monomer Conversion Rate Test
[0101] Take 10 mL of the reaction solution samples from Examples 1-3 and Control Groups 1-2 onto a glass dish, then add freshly prepared 3% hydroquinone aqueous solution. Place the glass dish in an oven and dry at 80°C until the mass no longer changes. Then calculate the monomer conversion rate of the reaction solution samples. , . This represents the actual solid content of the reaction solution sample. This represents the theoretical solids content of the reaction solution sample. The timing of adding the precursor solution is controlled by testing the monomer conversion rate of the reaction system.
[0102] 2. Emulsion viscosity test
[0103] According to the Mark-Houwink empirical equation, the molecular weight and intrinsic viscosity of a polymer satisfy the following relationship: In the formula Indicates intrinsic viscosity; It represents a proportionality constant that depends on the various conditions in the reaction; Represents the viscosity-average molar mass of the polymer; It refers to an empirical parameter with a specific value range of 0.5-1, which is related to the internal structure of the polymer. In experiments, intrinsic viscosity is used to represent the average molecular weight of the reactants.
[0104] Take 50 mL of the emulsion samples from Examples 1-3 and Control Groups 1-2 after the reaction has stopped, dry them in an oven at 70°C, and after cooling to room temperature, accurately weigh 0.15 g of the emulsion. Dissolve the emulsion completely in chloroform as a solvent in a 50 mL volumetric flask. Then, place the volumetric flask in a constant temperature water bath at 25°C for 1 hour, and then make up to volume. Finally, use an Ubbelohde viscometer to measure the viscosity of the solution prepared in the volumetric flask and the viscosity of the solvent chloroform. The formula for calculating the intrinsic viscosity is as follows:
[0105]
[0106] in, Represents relative viscosity; This represents the time it takes for the solution in the volumetric flask to flow through the capillary tube in the Ubbelohde viscometer's graduated section; The time it takes for the solvent chloroform to flow through a capillary in the same graduation section of the Ubbelohde viscometer; Indicates the concentration of the solution; Represents specific viscosity; This represents the intrinsic viscosity. Specific test results are as follows: Figure 1 As shown.
[0107] 3. Foaming performance test
[0108] Accurately weigh 110g of PVC (model PR-1069), 90g of liquefied MDI, 2.5g of epoxidized soybean oil, 5g of azobisisobutyronitrile, 0.5g of sodium bicarbonate, and 5g of the PVC foaming regulator from Examples 1-3 and Control Groups 1-2. Use a high-speed disperser to vacuum stir the mixture to obtain a paste. Then, transfer the paste mixture to a sealed mold and place it in a flat vulcanizing agent. Heat at 175℃ and 11MPa for 6 minutes, then cool to 80℃, open the mold, and release the pressure to obtain a pre-foamed preform. Place it in an 85℃ constant temperature water bath for secondary expansion and foaming. After 40 minutes, remove it and place it in a steam oven to cure at 80℃ for 15 days to obtain a foam sample. The microstructure of the foam sample was tested using scanning electron microscopy. The test results are as follows: Figure 2-6 As shown, the foam structures of Examples 1-3 are finer and more uniform than those of the control group, with no obvious signs of bubble merging and collapse, resulting in better foaming performance.
[0109] 4. Take the foam sample prepared above, and cut it into cube specimens with dimensions of 45mm × 45mm × 30mm according to ASTM D1621-04a standard. Use a computer-controlled universal testing machine to test the stress-strain curve of the cube specimens at a compression rate of 3mm / min. The results are as follows. Figure 7 As shown, the foam samples of Examples 1-3 of this application have better mechanical properties and higher foaming quality.
[0110] 5. The cyclodextrin derivative and β-cyclodextrin derivative from Example 2 were subjected to infrared spectroscopy. The test results are as follows: Figure 8 As shown, where, Figure 8 The above are cyclodextrin derivatives. Figure 8 The following is β-cyclodextrin.
[0111] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this invention.
Claims
1. A preparation process for a PVC foaming regulator, characterized in that: Includes the following steps: 1) A preemulsion is prepared by blending mixed monomers, emulsifiers, and water; the mixed monomers include MMA and BA; 2) A precursor solution is prepared by dissolving cyclodextrin derivative, disaccharide, and amino-terminated polyethylene glycol in a solvent, followed by the addition of maleimide; the mass ratio of cyclodextrin derivative, disaccharide, and amino-terminated polyethylene glycol is 1:(0.1-0.15):(0.3-0.5); the cyclodextrin derivative is prepared by the following steps: S1: cyclodextrin and sodium hydroxide are dissolved in deionized water, followed by the addition of an ethanol solution of p-toluenesulfonic acid imidazole, and the reaction yields an intermediate product; S2: the intermediate product is dissolved in DMF, N-vinylimidazolium is added, and after microwave reaction, the DMF is removed to obtain the final product; 3) Take the pre-emulsion for polymerization. When the monomer conversion rate is 70-80%, add the precursor liquid to the reaction system. The volume ratio of pre-emulsion to precursor liquid is 1:(0.15-0.2). Continue the reaction until the internal temperature drops, then stop the reaction. Add 3-aminophenylboronic acid and bis(trifluoromethanesulfonyl)imide. The amount of 3-aminophenylboronic acid added accounts for 2-3% of the mass of the pre-emulsion; the amount of bis(trifluoromethanesulfonyl)imide added accounts for 0.5-1% of the mass of the pre-emulsion. Then freeze-demulsify, dry and pulverize to obtain the final product.
2. The preparation process of the PVC foaming regulator according to claim 1, characterized in that: In step 1), the mixed monomers are composed of MMA and BA in a mass ratio of (9-13):
1. And / or, in step 1), the emulsifier is one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium dodecylaminopropionate, and hexadecyltrimethylammonium bromide; And / or, in step 1), the mass of the emulsifier accounts for 3-5 wt% of the mass of the mixed monomers.
3. The preparation process of the PVC foaming regulator according to claim 1, characterized in that: In step 2), the disaccharide is one or more of lactose, trehalose, and maltose.
4. The preparation process of the PVC foaming regulator according to claim 1, characterized in that: In step S1, the molar ratio of cyclodextrin to p-toluenesulfonic acid imidazole is 1:(1.2-1.5).
5. The preparation process of the PVC foaming regulator according to claim 1, characterized in that: In step S2, the molar ratio of cyclodextrin to N-vinylimidazole is controlled to be 1:(1.5-2).
6. A PVC foaming regulator, characterized in that: It is prepared using the preparation process described in any one of claims 1-5.