PVC (polyvinyl chloride) foaming regulator and preparation process thereof

Abstract

The invention belongs to the technical field of PVC foaming agents, and particularly provides a PVC foaming regulator and a preparation process thereof, the preparation process of the PVC foaming regulator comprises the following steps: 1) blending a mixed monomer, an emulsifier and water to prepare a pre-emulsion; the mixed monomer comprises MMA (methyl methacrylate) and BA (butyl acrylate); 2) dissolving a cyclodextrin derivative, disaccharide and modified polyethylene glycol in a solvent, and then adding maleimide to react to prepare a precursor solution; 3, the pre-emulsion is taken for a polymerization reaction, when the monomer conversion rate ranges from 70% to 80%, the precursor solution is added into a reaction system, the reaction continues till the inner temperature drops, the reaction is stopped, then freezing demulsification and drying pulverization are conducted, and the PVC foaming regulator is obtained.The prepared PVC foaming regulator has the advantages of being moderate in intrinsic viscosity and good in foaming effect.

Description

Technical Field

[0001] The present invention relates to the technical field of PVC foaming agents, and in particular to a PVC foaming regulator and a preparation process thereof. Background Art

[0002] PVC foam products are waterproof, flame retardant, acid and alkali resistant, moth-proof, lightweight, heat-insulating, sound-insulating and shock-absorbing. They are ideal substitutes for wood, aluminum and composite panels. They are widely used in interior decoration panels, building exterior wall panels, interior decoration panels, offices, residences, public buildings and other fields, and have very important application value.

[0003] With the development of PVC material technology, people have higher and higher requirements on the performance of PVC foam products. At the same time, in the application process of PVC foam products, there are problems such as poor foam impact resistance, long foam processing cycle, and low processing efficiency. Therefore, it is necessary to improve the foaming performance of foam products to solve the above problems.

[0004] In the PVC foaming process, acrylic foaming regulators have the functions of improving the processing performance of PVC, promoting the plasticizing performance of PVC, adjusting the pore structure of bubbles generated in the foaming process, and improving the strength of the PVC foaming melt, which can prevent a large number of bubbles from merging and is very helpful for obtaining uniformly foamed PVC products. Acrylic foaming regulators are a kind of acrylic multipolymer with ultra-high molecular weight and multi-layer structure. Its chemical composition is obtained by multi-stage emulsion polymerization of acrylic monomers and other monomers. Its preparation and synthesis process are also a very critical research issue in the current PVC foaming process.

[0005] For example, a patent application document with application publication number CN117757129A discloses a PVC foaming regulator and a preparation method thereof. The regulator is prepared by dehydrating and drying a polymer emulsion, and the polymer emulsion is prepared by mixing acrylate compounds, methacrylate compounds, pH regulators, initiators, etc. The PVC foaming regulator is prepared by copolymerizing multiple compounds, and the intrinsic viscosity of the obtained copolymer is higher than that of the copolymer obtained by a single initiator system.

[0006] For another example, the patent application document with application publication number CN112940168A discloses a production process for a high-viscosity PVC foaming regulator. By changing the initiation mode and adopting a redox composite initiation system, the reaction is accelerated, thereby increasing the reaction rate and the molecular weight of the polymer. By controlling the amount of each raw material component and the reaction conditions, the emulsion polymerization reaction is carried out at a lower initiation temperature and a smaller amount of initiator to obtain a copolymer with a larger molecular weight, thereby increasing the intrinsic viscosity of the PVC foaming regulator.

[0007] For acrylic foaming regulators, molecular weight is a very important indicator. As the molecular weight of acrylic foaming regulators increases, they can play a better role in stabilizing and enhancing foams during the foaming process. However, when the dosage and molecular weight of acrylic foaming regulators reach a certain limit, on the one hand, the molecular weight of acrylic foaming regulators is too large, and the synthesis difficulty and cost are high. On the other hand, the excessive molecular weight leads to excessively high viscosity, which also has an adverse effect on the control of the foaming process. Therefore, how to improve the foaming effect of PVC within a certain molecular weight range is a technical problem that needs to be solved urgently. Summary of the invention

[0008] In view of the above problems, in order to further improve the performance of acrylic foaming regulators, the present application provides a PVC foaming regulator and a preparation process thereof.

[0009] The present application first provides a preparation process of a PVC foaming regulator, comprising the following steps: 1) Mixing a mixed monomer, an emulsifier and water to prepare a pre-emulsion; the mixed monomer includes MMA and BA; 2) dissolving cyclodextrin derivatives, disaccharides and modified polyethylene glycol in a solvent, and then adding maleimide to react to prepare a precursor solution; 3) Take the pre-emulsion for polymerization reaction. When the monomer conversion rate is 70-80%, add the precursor liquid into the reaction system, continue the reaction until the internal temperature drops, stop the reaction, then freeze and demulsify, and dry and powder to obtain.

[0010] Furthermore, in the step 1), the mixed monomer consists of MMA and BA in a mass ratio of (9-13):1; And / or, in the 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 3-5wt% of the mass of the mixed monomers.

[0011] Furthermore, in the step 2), the mass ratio of the cyclodextrin derivative, the disaccharide, and the modified polyethylene glycol is 1:(0.1-0.15):(0.3-0.5); And / or, in the step 2), the modified polyethylene glycol is one of amino-terminated polyethylene glycol, carboxyl-terminated polyethylene glycol, and hydroxyl-terminated polyethylene glycol; And / or, in step 2), the disaccharide is one or more of lactose, trehalose and maltose.

[0012] Furthermore, in step 3), the volume ratio of the pre-emulsion to the precursor solution is 1:(0.15-0.2).

[0013] Furthermore, in step 2), the cyclodextrin derivative is prepared by the following steps: S1: dissolving cyclodextrin and sodium hydroxide in deionized water, and then adding ethanol solution of p-toluenesulfonic acid imidazole to obtain an intermediate product after reaction; S2: The intermediate product is dissolved in DMF, N-vinyl imidazole is added, microwave reaction is performed, and then DMF is removed to obtain the product.

[0014] Furthermore, in step S1, the molar ratio of cyclodextrin to p-toluenesulfonic acid imidazole is 1:(1.2-1.5).

[0015] Furthermore, in step S2, the molar ratio of cyclodextrin to N-vinylimidazole is controlled to be 1:(1.5-2).

[0016] Furthermore, in the step 3), 3-aminophenylboronic acid and bis(trifluoromethylsulfonimide) are added after the reaction is stopped.

[0017] Furthermore, in the step 3), the amount of 3-aminophenylboronic acid added is 2-3% of the mass of the pre-emulsion; the amount of bistrifluoromethylsulfonimide added is 0.5-1% of the mass of the pre-emulsion.

[0018] The present application also provides a PVC foaming regulator, which is prepared by the above-mentioned preparation process.

[0019] Compared with the prior art, this application has the following beneficial effects: 1. The present application uses MMA and BA as mixed monomers and adopts a direct mixing reaction method to form a cross-linked transition layer between the copolymer products of MMA and BA, thereby improving the compatibility of the copolymer products and increasing the molecular weight of the reaction products. In the foaming process, the bubble pore structure generated by the decomposition of the foaming agent can be optimized and adjusted, the strength of the PVC foam material can be improved, and a large number of bubbles can be prevented from merging during the foaming process, thereby obtaining a uniform and fine foaming structure of the bubbles.

[0020] 2. The present application introduces a precursor liquid at an appropriate time point during the monomer polymerization reaction, and a long-chain molecular sliding ring structure is formed between the cyclodextrin derivative in the precursor liquid and the modified polyethylene glycol. In the foaming process, the long molecular chains of the precursor liquid are entangled and attached to the molecular chains of PVC and the foaming regulator, forming a dynamic elastic network structure to a certain extent, so that the PVC melt can maintain sufficient fluidity and improve the toughness and strength of the bubble wall, so that the bubbles are well coated, ensuring that the gas generated by the decomposition of the foaming agent can be refined to form smaller bubbles, reducing and preventing the collapse and merging of bubbles, and finally ensuring that a complete and uniform bubble pore structure is obtained, thereby improving the PVC foaming effect and product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the intrinsic viscosity data of the PVC foaming regulators of Examples 1-3 and Control Groups 1-2 of the present application; Figure 2 This is a SEM image of the foam sample of Example 1 of the present application; Figure 3 This is a SEM image of the foam sample of Example 2 of the present application; Figure 4 This is a SEM image of the foam sample of Example 3 of the present application; Figure 5 This is the SEM image of the foam sample of the control group 1 of this application; Figure 6 This is the SEM image of the foam sample of control group 2 of this application; Figure 7 Schematic diagram of compressive stress-strain data of foam samples of Examples 1-3 and Control Groups 1-2 of the present application; Figure 8 This is a comparison chart of infrared spectra of the cyclodextrin derivative and β-cyclodextrin in Example 2 of the present application. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0023] After a large number of experimental studies, the present application optimizes the monomer type and monomer ratio, adopts a mixed polymerization method, improves the compatibility between monomers and copolymers, and compounded a precursor solution containing a cyclodextrin derivative, so that the PVC foaming regulator has a better foaming effect within a certain intrinsic viscosity range. Specifically, the present application embodiment provides a preparation process of a PVC foaming regulator, comprising the following steps: 1) Mixing a mixed monomer, an emulsifier and water to prepare a pre-emulsion; the mixed monomer includes MMA and BA; 2) dissolving cyclodextrin derivatives, disaccharides and modified polyethylene glycol in a solvent, and then adding maleimide to react to prepare a precursor solution; 3) Take the pre-emulsion for polymerization reaction. When the monomer conversion rate is 70-80%, add the precursor liquid into the reaction system, continue the reaction until the internal temperature drops, stop the reaction, then freeze and demulsify, and dry and powder to obtain.

[0024] Furthermore, in the step 1), the mixed monomer consists of MMA and BA in a mass ratio of (9-13):1; And / or, in the 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 3-5wt% of the mass of the mixed monomers.

[0025] In some specific embodiments, in the step 1), the mixed monomer may 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, 13:1. More preferably, under normal circumstances, in the step 1), when the mixed monomer is composed of MMA and BA in a mass ratio of 12.5:1, better experimental results can be obtained.

[0026] In some specific embodiments, generally, in step 1), when the emulsifier is sodium dodecyl sulfate, the experimental effect is best.

[0027] In some specific embodiments, in step 1), the mass of the emulsifier may account for 3wt%, 3.3wt%, 3.5wt%, 3.7wt%, 3.85wt%, 4wt%, 4.2wt%, 4.5wt%, 4.8wt%, 5wt% of the mass of the mixed monomers. Under normal circumstances, in step 1), when the mass of the emulsifier accounts for 3.5% of the mass of the mixed monomers, better experimental results can be obtained.

[0028] Furthermore, in the step 2), the mass ratio of the cyclodextrin derivative, the disaccharide, and the modified polyethylene glycol is 1:(0.1-0.15):(0.3-0.5); And / or, in the step 2), the modified polyethylene glycol is one of amino-terminated polyethylene glycol, carboxyl-terminated polyethylene glycol, and hydroxyl-terminated polyethylene glycol; And / or, in step 2), the disaccharide is one or more of lactose, trehalose and maltose.

[0029] Furthermore, in step 3), the volume ratio of the pre-emulsion to the precursor solution is 1:(0.15-0.2).

[0030] In some specific embodiments, in the step 2), the mass ratio of the cyclodextrin derivative, the disaccharide, and the 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, 1:0.1:0.4. 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, 1:0.15:0.5. Under normal experimental conditions, in the step 2), when the mass ratio of the cyclodextrin derivative, the disaccharide and the modified polyethylene glycol is 1:0.1:0.35, better experimental results can be obtained.

[0031] In some specific embodiments, under normal circumstances, in the step 2), when the modified polyethylene glycol is amino-terminated polyethylene glycol, better experimental results can be obtained.

[0032] In some specific embodiments, under normal circumstances, in the step 2), when the disaccharide consists of lactose and trehalose in a mass ratio of 2:1, better experimental results can be obtained.

[0033] 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, 1:0.2. Generally, in step 3), when the volume ratio of the pre-emulsion to the precursor solution is 1:0.165, better experimental results can be obtained.

[0034] In some specific embodiments, under normal circumstances, when the monomer conversion rate is 75%, a precursor solution is added to the reaction system, and better experimental results can be obtained.

[0035] Furthermore, in step 2), the cyclodextrin derivative is prepared by the following steps: S1: dissolving cyclodextrin and sodium hydroxide in deionized water, and then adding ethanol solution of p-toluenesulfonic acid imidazole to obtain an intermediate product after reaction; S2: The intermediate product is dissolved in DMF, N-vinyl imidazole is added, microwave reaction is performed, and then DMF is removed to obtain the product.

[0036] Furthermore, in step S1, the molar ratio of cyclodextrin to p-toluenesulfonic acid imidazole is 1:(1.2-1.5).

[0037] Furthermore, in step S2, the molar ratio of cyclodextrin to N-vinylimidazole is controlled to be 1:(1.5-2).

[0038] Furthermore, in the step 3), 3-aminophenylboronic acid and bis(trifluoromethylsulfonimide) are added after the reaction is stopped.

[0039] Furthermore, in the step 3), the amount of 3-aminophenylboronic acid added is 2-3% of the mass of the pre-emulsion; the amount of bistrifluoromethylsulfonimide added is 0.5-1% of the mass of the pre-emulsion.

[0040] In some specific embodiments, generally, when β-cyclodextrin is used as the cyclodextrin, better experimental results can be obtained.

[0041] In some specific embodiments, in step S1, the molar ratio of cyclodextrin to p-toluenesulfonyl imidazole can be 1:1.2, 1:1.25, 1:1.3, 1:1.35, 1:1.4, 1:1.45, 1:1.5. Generally, when the molar ratio of cyclodextrin to p-toluenesulfonyl imidazole in step S1 is 1:1.3, the experimental effect is better.

[0042] 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, 1:2. In general, in step S2, when the molar ratio of cyclodextrin to N-vinylimidazole is controlled to be 1:1.55, the experimental effect is better.

[0043] In some specific embodiments, in step 3), the amount of 3-aminophenylboronic acid added may account for 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3% of the mass of the pre-emulsion; the amount of bis(trifluoromethylsulfonyl)imide added may account for 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1% of the mass of the pre-emulsion. Under normal circumstances, in step 3), when the amount of 3-aminophenylboronic acid added accounts for 2.5% of the mass of the pre-emulsion and the amount of bis(trifluoromethylsulfonyl)imide added accounts for 0.85% of the mass of the pre-emulsion, better experimental results can be obtained.

[0044] Example 1 The preparation process of the PVC foaming regulator of this embodiment comprises the following steps: 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, a stirrer, a condenser, and a constant pressure funnel, mix well, and then add 200 g of MMA and 16 g of BA to prepare a pre-emulsion; wherein, MMA and BA are first washed with a 5% sodium hydroxide solution, and then washed with deionized water until neutral, and dried for use; 2) Add 200 mL of anhydrous ethanol to a 500 mL four-necked flask equipped with a thermometer, a stirrer, and a constant pressure funnel, then add 20 g of a cyclodextrin derivative, 2 g of a disaccharide, and 7 g of amino-terminated polyethylene glycol and mix evenly, adjust the pH value to be weakly alkaline, then add maleimide, react at 50°C for 2 h, then evaporate a portion of the anhydrous ethanol to obtain a 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; 3) Add 0.2g potassium persulfate and 0.2g sodium sulfite to the above pre-emulsion and mix evenly, heat to 65°C, and carry out polymerization reaction under nitrogen protection. When the monomer conversion rate is 75%, add precursor liquid to the reaction system (control the volume ratio of pre-emulsion to precursor liquid to be 1:0.165), heat to 75°C and continue to react until the internal temperature drops to 50°C, stop the reaction, then freeze and demulsify, dry and pulverize to obtain PVC foaming regulator.

[0045] Example 2 The preparation process of the PVC foaming regulator of this embodiment comprises the following steps: 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, a stirrer, a condenser, and a constant pressure funnel, mix well, and then add 200 g of MMA and 16 g of BA to prepare a pre-emulsion; wherein, MMA and BA are first washed with a 5% sodium hydroxide solution, and then washed with deionized water until neutral, and dried for use; 2) Add 200 mL of anhydrous ethanol to a 500 mL four-necked flask equipped with a thermometer, a stirrer, and a constant pressure funnel, then add 20 g of a cyclodextrin derivative, 2 g of a disaccharide, and 7 g of amino-terminated polyethylene glycol and mix evenly, adjust the pH value to be weakly alkaline, then add maleimide, react at 50°C for 2 h, then evaporate a portion of the anhydrous ethanol to obtain a 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; 3) Add 0.2g potassium persulfate and 0.2g sodium sulfite to the above pre-emulsion and mix evenly, heat to 65°C, and carry out polymerization reaction under nitrogen protection. When the monomer conversion rate is 75%, add precursor liquid to the reaction system (control the volume ratio of pre-emulsion to precursor liquid to be 1:0.165), heat to 75°C and continue to react until the internal temperature drops to 50°C, stop the reaction, then freeze and demulsify, dry and pulverize to obtain PVC foaming regulator.

[0046] The cyclodextrin derivative of this embodiment is prepared by the following steps: S1: Add 200 g of deionized water, 25 g of cyclodextrin, and 5.5 g of sodium hydroxide into a four-necked flask and mix well, then add an ethanol solution of p-toluenesulfonic acid imidazole (the molar ratio of cyclodextrin to p-toluenesulfonic acid imidazole is controlled to be 1:1.3), react at room temperature, distill, wash with deionized water, and dry to obtain an intermediate product; S2: The intermediate product obtained in step S1 was transferred to another four-necked flask, 250 mL of DMF was added, and the mixture was stirred until completely dissolved. Then, N-vinylimidazole was added (the molar ratio of cyclodextrin to N-vinylimidazole was controlled to be 1:1.55), and the mixture was subjected to microwave reaction for 4 h under nitrogen protection. The DMF was removed by distillation to obtain the product.

[0047] Example 3 The preparation process of the PVC foaming regulator of this embodiment comprises the following steps: 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, a stirrer, a condenser, and a constant pressure funnel, mix well, and then add 200 g of MMA and 16 g of BA to prepare a pre-emulsion; wherein, MMA and BA are first washed with a 5% sodium hydroxide solution, and then washed with deionized water until neutral, and dried for use; 2) Add 200 mL of anhydrous ethanol to a 500 mL four-necked flask equipped with a thermometer, a stirrer, and a constant pressure funnel, then add 20 g of a cyclodextrin derivative, 2 g of a disaccharide, and 7 g of amino-terminated polyethylene glycol and mix evenly, adjust the pH value to be weakly alkaline, then add maleimide, react at 50°C for 2 h, then evaporate a portion of the anhydrous ethanol to obtain a 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; 3) Add 0.2g potassium persulfate and 0.2g sodium sulfite to the pre-emulsion and mix evenly, heat to 65°C, and carry out polymerization reaction under nitrogen protection. When the monomer conversion rate is 75%, add the precursor solution to the reaction system (control the volume ratio of the pre-emulsion to the precursor solution to be 1:0.165), heat to 75°C and continue to react until the internal temperature drops to 50°C, stop the reaction, then add 3-aminophenylboronic acid and bistrifluoromethylsulfonyl imide (control the amount of 3-aminophenylboronic acid added to account for 2.5% of the mass of the pre-emulsion, and the amount of bistrifluoromethylsulfonyl imide added to account for 0.85% of the mass of the pre-emulsion), continue stirring for 30 minutes, then freeze and demulsify, dry and pulverize to obtain a PVC foaming regulator.

[0048] The cyclodextrin derivative of this embodiment is prepared by the following steps: S1: Add 200 g of deionized water, 25 g of cyclodextrin, and 5.5 g of sodium hydroxide into a four-necked flask and mix well, then add an ethanol solution of p-toluenesulfonic acid imidazole (the molar ratio of cyclodextrin to p-toluenesulfonic acid imidazole is controlled to be 1:1.3), react at room temperature, distill, wash with deionized water, and dry to obtain an intermediate product; S2: The intermediate product obtained in step S1 was transferred to another four-necked flask, 250 mL of DMF was added, and the mixture was stirred until completely dissolved. Then, N-vinylimidazole was added (the molar ratio of cyclodextrin to N-vinylimidazole was controlled to be 1:1.55), and the mixture was subjected to microwave reaction for 4 h under nitrogen protection. The DMF was removed by distillation to obtain the product.

[0049] Control group 1 The preparation process of the PVC foaming regulator of this control group includes the following steps: 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, a stirrer, a condenser, and a constant pressure funnel, mix well, and then add 200 g of MMA and 16 g of BA to prepare a pre-emulsion; wherein, MMA and BA are first washed with a 5% sodium hydroxide solution, and then washed with deionized water until neutral, and dried for use; 2) Add 0.2 g potassium persulfate and 0.2 g sodium sulfite to the pre-emulsion and mix well. Heat to 65°C and carry out polymerization reaction under nitrogen protection until the internal temperature drops to 50°C. Then freeze-break the emulsion and dry and powderize to obtain a PVC foaming regulator.

[0050] Control group 2 The preparation process of the PVC foaming regulator of this control group includes the following steps: 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, a stirrer, a condenser, and a constant pressure funnel, mix well, and then add 200 g of MMA and 16 g of BA to prepare a pre-emulsion; wherein, MMA and BA are first washed with a 5% sodium hydroxide solution, and then washed with deionized water until neutral, and dried for use; 2) Add 0.2g potassium persulfate and 0.2g sodium sulfite to the above pre-emulsion and mix evenly, heat to 65°C, and carry out polymerization reaction under nitrogen protection. When the monomer conversion rate is 75%, add amino-terminated polyethylene glycol to the reaction system (control the volume ratio of pre-emulsion and amino-terminated polyethylene glycol to be 1:0.165, and the average polymerization degree of amino-terminated polyethylene glycol n=13), heat to 75°C and continue to react until the internal temperature drops to 50°C, stop the reaction, then freeze and demulsify, dry and pulverize to obtain PVC foaming regulator.

[0051] Performance Testing 1. Monomer conversion rate test Take 10 mL of the reaction solution sample of the reaction system of Example 1-3 and the control group 1-2 on a glass dish, then drop a freshly prepared 3% mass fraction of hydroquinone aqueous solution, then put the glass dish into an oven and dry it at 80°C until the mass no longer changes, and then calculate the monomer conversion rate of the reaction solution sample , . is the actual solid content of the reaction solution sample, is the theoretical solid content of the reaction solution sample. The time point for adding the precursor solution is regulated by testing the monomer conversion rate of the reaction system.

[0052] 2. Emulsion viscosity test According to the Mark-Houwink empirical equation, we know that the molecular weight and intrinsic viscosity of the polymer satisfy the following relationship: , in the formula It represents the intrinsic viscosity; Represents a proportionality constant that depends on the conditions of 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 the experiment, the intrinsic viscosity is used to represent the average molecular weight of the reactants.

[0053] Take 50 mL of the emulsion samples of Example 1-3 and Control Group 1-2 after the reaction is stopped, put them into an oven at 70°C for drying, and after cooling to room temperature, accurately weigh 0.15 g, and completely dissolve them in a 50 mL volumetric flask using chloroform as a solvent, then put the volumetric flask into a constant temperature water bath set at 25°C for 1 hour, and take out and adjust the 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, and the formula for calculating the intrinsic viscosity is as follows: in, represents relative viscosity; Represents the time it takes for the solution in the volumetric flask to flow through the capillary of the scale section in the Ubbelohde viscometer; It represents the time for the solvent chloroform to flow through the capillary of the same scale segment in the Ubbelohde viscometer; Indicates the concentration of the solution; stands for specific viscosity; Represents intrinsic viscosity. Specific test results are as follows Figure 1 shown.

[0054] 3. Foaming performance test 110g PVC (model PR-1069), 90g liquefied MDI, 2.5g epoxy soybean oil, 5g azobisisobutyronitrile, 0.5g sodium bicarbonate, and 5g PVC foaming regulator of Examples 1-3 and Control Groups 1-2 were accurately weighed, and a high-speed disperser was used to vacuum stir to obtain a paste mixture, and then the paste mixture was transferred to a sealed mold, and then placed in a flat vulcanizer, heated at a temperature of 175°C and a pressure of 11MPa for 6min, and then cooled to 80°C, the mold was opened and the pressure was released to obtain a pre-foamed body, which was placed in a constant temperature water tank at 85°C for secondary expansion and foaming, taken out after 40min, placed in a steamer, and cured at 80°C for 15 days to obtain a foam sample, and the foam microstructure of the foam sample was tested by an electron scanning electron microscope. The test results are as follows: Figure 2-6 It can be seen that the foam structures of Examples 1-3 are finer and more uniform than those of the control group, without obvious bubble fusion and collapse, and the foaming effect is better.

[0055] 4. Take the foam sample prepared above and cut it in advance according to ASTM D1621-04a standard to obtain a cubic specimen with a size of 45 mm × 45 mm × 30 mm. Use a computer-controlled universal testing machine to test the stress-strain curve of the cubic specimen at a compression rate of 3 mm / min. The results are as follows: Figure 7 As shown, it can be seen that the foam samples of Examples 1-3 of the present application have better mechanical properties and higher foaming quality.

[0056] 5. The cyclodextrin derivative and β-cyclodextrin derivative of Example 2 were tested by infrared spectroscopy. The test results were as follows: Figure 8 As shown, Figure 8 The above are cyclodextrin derivatives, Figure 8 The following is β-cyclodextrin.

[0057] Although the present application has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present invention.

Claims

1. A preparation process of a PVC foaming regulator, characterized in that: The steps include: 1) Mixing a mixed monomer, an emulsifier and water to prepare a pre-emulsion; the mixed monomer includes MMA and BA; 2) dissolving cyclodextrin derivatives, disaccharides and modified polyethylene glycol in a solvent, and then adding maleimide to react to prepare a precursor solution; 3) Take the pre-emulsion for polymerization reaction. When the monomer conversion rate is 70-80%, add the precursor liquid into the reaction system, continue the reaction until the internal temperature drops, stop the reaction, then freeze and demulsify, and dry and powder to obtain.

2. The preparation process of the PVC foaming regulator according to claim 1, characterized in that: In the step 1), the mixed monomers are composed of MMA and BA in a mass ratio of (9-13):1; And / or, in the 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 3-5wt% of the mass of the mixed monomers.

3. The preparation process of the PVC foaming regulator according to claim 1, characterized in that: In the step 2), the mass ratio of cyclodextrin derivative, disaccharide and modified polyethylene glycol is 1:(0.1-0.15):(0.3-0.5); And / or, in the step 2), the modified polyethylene glycol is one of amino-terminated polyethylene glycol, carboxyl-terminated polyethylene glycol, and hydroxyl-terminated polyethylene glycol; And / or, 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 the step 3), the volume ratio of the pre-emulsion to the precursor solution is 1:(0.15-0.2).

5. The preparation process of the PVC foaming regulator according to claim 3, characterized in that: In the step 2), the cyclodextrin derivative is prepared by the following steps: S1: dissolving cyclodextrin and sodium hydroxide in deionized water, and then adding ethanol solution of p-toluenesulfonic acid imidazole to obtain an intermediate product after reaction; S2: The intermediate product is dissolved in DMF, N-vinyl imidazole is added, microwave reaction is performed, and then DMF is removed to obtain the product.

6. The preparation process of the PVC foaming regulator according to claim 5, characterized in that: In the step S1, the molar ratio of cyclodextrin to p-toluenesulfonic acid imidazole is 1:(1.2-1.5).

7. The preparation process of the PVC foaming regulator according to claim 5, characterized in that: In the step S2, the molar ratio of cyclodextrin to N-vinylimidazole is controlled to be 1:(1.5-2).

8. The preparation process of the PVC foaming regulator according to claim 1, characterized in that: In the step 3), 3-aminophenylboronic acid and bis(trifluoromethylsulfonimide) are added after the reaction is stopped.

9. The preparation process of the PVC foaming regulator according to claim 8, characterized in that: In the step 3), the amount of 3-aminophenylboronic acid added is 2-3% of the mass of the pre-emulsion; the amount of bistrifluoromethylsulfonimide added is 0.5-1% of the mass of the pre-emulsion.

10. A PVC foaming regulator, characterized in that: The method is prepared by the preparation process described in any one of claims 1 to 9.

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