A transparent PVC processing modifier and its preparation method

Abstract

The present invention provides a transparent PVC processing modifier and a preparation method thereof, belonging to the field of PVC processing modifiers. The preparation method of the transparent PVC processing modifier includes the following steps: a first-stage reaction and a second-stage reaction. The preparation method of the transparent PVC processing modifier of the present invention can reduce the melt viscosity of polyvinyl chloride, improve the melt fluidity of polyvinyl chloride, improve the processing and molding performance, while improving the transparency and haze of polyvinyl chloride products, and improving their fracture toughness in a low-temperature environment; and avoid the adverse effects of the transparent PVC processing modifier on the polyvinyl chloride melt, adjust the stable processing torque, and improve the thermal stability of polyvinyl chloride products.

Description

Technical Field

[0001] The present invention relates to the field of PVC processing modifiers, and particularly to a transparent PVC processing modifier and a preparation method thereof. Background Art

[0002] Polyvinyl chloride (PVC) is one of the most widely used plastic varieties in current application fields due to its good flame retardancy, abrasion resistance, chemical corrosion resistance, comprehensive mechanical properties, product transparency, electrical insulation and easy processability, etc. It has a wide range of applications in industries, construction, agriculture, daily life, packaging, electricity, public utilities and other fields, and is called one of the five general-purpose resins together with polyethylene (PE), polypropylene (PP), polystyrene (PS) and ABS. However, the existing polyvinyl chloride has disadvantages such as high melt viscosity, poor fluidity, narrow molding temperature range, easy coking and decomposition, and uneven processing and molding performance. Therefore, a processing modifier must be added during the processing of PVC products.

[0003] Acrylate copolymer (ACR) is the main processing modifier in PVC processing, which can significantly shorten the plasticization time, accelerate melting and promote plasticization. Acrylate resin (ACR) is a thermoplastic graft polymer mainly obtained by emulsion polymerization of methyl methacrylate (MMA) and acrylate (such as butyl acrylate, ethyl acrylate). Acrylate processing aids can greatly improve and enhance the impact resistance and processing performance of PVC products, and reduce the scrap rate in production.

[0004] However, the addition of acrylate copolymer processing modifier, although it can reduce the melt viscosity of polyvinyl chloride to a certain extent, improve the melt fluidity of polyvinyl chloride, and improve the processing and molding performance, it will affect the fracture toughness of polyvinyl chloride material in a low-temperature environment and cause a certain degree of increase in the haze of polyvinyl chloride material, affecting transparency; at the same time, the addition of acrylate copolymer processing modifier will also significantly affect the processing torque and melt strength of polyvinyl chloride melt, and there is a problem of sudden increase in processing torque during the processing, not only the processing stability is poor, but also there will be residual stress inside the PVC product, resulting in poor thermal stability of the PVC product.

[0005] Therefore, there is provided a transparent PVC processing modifier and a preparation method thereof, which can reduce the melt viscosity of polyvinyl chloride, improve the melt fluidity of polyvinyl chloride, improve the processing and molding performance, while improving the transparency and haze of PVC products, and improving their fracture toughness in a low-temperature environment; and avoid the adverse effects of the transparent PVC processing modifier on the polyvinyl chloride melt, adjust and stabilize the processing torque, and improve the thermal stability of PVC products. Summary of the Invention

[0006] To solve the technical problems existing in the prior art, the present invention provides a transparent PVC processing modifier and its preparation method, which can reduce the melt viscosity of polyvinyl chloride, improve the melt fluidity of polyvinyl chloride, improve the processing and molding performance, while improving the transparency and haze of polyvinyl chloride products, and improving their fracture toughness in low-temperature environments; and avoid the adverse effects of the transparent PVC processing modifier on the polyvinyl chloride melt, adjust the stable processing torque, and improve the thermal stability of polyvinyl chloride products.

[0007] To solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0008] A preparation method of a transparent PVC processing modifier, comprising the following steps: a first-stage reaction and a second-stage reaction;

[0009] In the first-stage reaction, deionized water, sodium dodecylbenzenesulfonate, methyl methacrylate, butyl acrylate, styrene, and vinyl acetate are mixed evenly, and then, in an inert gas environment and in the presence of an initiator, the temperature is raised for reaction to obtain a first-stage reaction product;

[0010] In the second-stage reaction, the first-stage reaction product, butyl methacrylate, acrylonitrile, isooctyl acrylate, and a composite modifier are mixed evenly, and then, in an inert gas environment and in the presence of an initiator, the temperature is raised for reaction to obtain a second-stage reaction product; the second-stage reaction product is spray-dried to obtain the transparent PVC processing modifier;

[0011] The preparation method of the composite modifier consists of the following steps: preparing a hyperbranched modifier and compounding;

[0012] In the preparation of the hyperbranched modifier, after a pre-reaction product is obtained by reacting cetyl dimethyl tertiary amine, N,N-dimethylethanolamine with epichlorohydrin, the temperature is raised for reaction in a solvent environment and in the presence of a catalyst to obtain the hyperbranched modifier;

[0013] In the compounding, after metal-organic framework ZIF-8 is thermally activated, the activated ZIF-8 and the hyperbranched modifier are mixed and subjected to ultrasonic treatment to obtain the composite modifier.

[0014] Further, in the first-stage reaction, the reaction pressure is 0.1 - 0.12 MPa, the reaction temperature is 62 - 68 °C, and the reaction time is 1 - 2 h;

[0015] In the second-stage reaction, the reaction pressure is 0.1 - 0.12 MPa, the reaction temperature is 70 - 75 °C, and the reaction time is 3 - 4 h.

[0016] Preferably, in the first-stage reaction, the weight ratio of deionized water, sodium dodecylbenzenesulfonate, methyl methacrylate, butyl acrylate, styrene, vinyl acetate, and initiator is 100-105:0.9-1.1:35-37:8-8.3:5-5.2:1.5-1.6:0.3-0.35.

[0017] Further, in the second-stage reaction, the weight ratio of the first-stage reactant, butyl methacrylate, acrylonitrile, isooctyl acrylate, composite modifier, and initiator is 100-105:50-53:16-17:7-8:7-7.5:0.4-0.45.

[0018] Further, for the preparation of the hyperbranched modifier, after mixing cetyl dimethyl tertiary amine and N,N-dimethylethanolamine evenly, the temperature is raised to 80-85 °C, and epichlorohydrin is added dropwise while maintaining the temperature; after the addition is complete, the mixture is stirred for 4-5 h while maintaining the temperature to remove the unreacted epichlorohydrin to obtain a pre-reactant; the pre-reactant, absolute ethanol, and catalyst are mixed and then reacted at 80-85 °C for 10-12 h to obtain the hyperbranched modifier.

[0019] Preferably, in the preparation of the hyperbranched modifier, the molar amount of epichlorohydrin is 1.02-1.05 times the total molar amount of cetyl dimethyl tertiary amine and N,N-dimethylethanolamine.

[0020] Preferably, in the preparation of the hyperbranched modifier, the weight ratio of the pre-reactant to absolute ethanol is 1:0.7-0.8;

[0021] The added weight of the catalyst is 2-2.5% of the weight of the pre-reactant.

[0022] Preferably, in the composite, the thermal activation vacuum is 0.05-0.07 MPa, the thermal activation temperature is 150-160 °C, and the thermal activation time is 4-5 h;

[0023] The ultrasonic treatment temperature is 35-40 °C, the ultrasonic treatment time is 30-50 min, the ultrasonic frequency is 25-30 KHz, and the ultrasonic power is 170-200 W.

[0024] Preferably, in the composite, the weight ratio of the activated ZIF-8 to the hyperbranched modifier is 4.2-4.6:100.

[0025] A transparent PVC processing modifier is prepared by the aforementioned preparation method.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] (1)The preparation method of the transparent PVC processing modifier of the present invention is as follows: after using methyl methacrylate, butyl acrylate, styrene, and vinyl acetate as the first-stage monomers for polymerization reaction, a first-stage reaction product is obtained; then, the first-stage reaction product, a composite modifier, and butyl methacrylate, acrylonitrile, and isooctyl acrylate as the second-stage monomers are used for polymerization reaction to obtain a second-stage reaction product, which is then spray-dried to obtain the transparent PVC processing modifier; and in the preparation of the composite modifier used, first, hexadecyl dimethyl tertiary amine, N,N-dimethylethanolamine, and epichlorohydrin are reacted. The hexadecyl dimethyl tertiary amine provides a hydrophobic long chain as the hydrophobic end group of the hyperbranched modifier, and N,N-dimethylethanolamine serves as a functionalized alkyl tertiary amine to provide hydroxyl and tertiary amine groups to promote the branching reaction and increase the crosslinking density; through the cooperation of the dual-active raw materials of hexadecyl dimethyl tertiary amine and N,N-dimethylethanolamine, a hyperbranched modifier with a multi-quaternary ammonium center and a multi-branched network structure is prepared by reaction; then, the hyperbranched modifier is compounded with heat-activated ZIF-8, and through the electrostatic and adsorption effects of the two, a composite modifier is prepared to improve the compatibility of the hyperbranched modifier with the second-stage monomers and improve the reaction uniformity of the subsequent second-stage polymerization; in the second-stage reaction, the composite modifier uses the metal active nodes of ZIF-8 as auxiliary initiation sites to initiate the polymerization of the second-stage monomers, and through the end groups of the hyperbranched modifier and the surface groups of ZIF-8 in the composite modifier, participate in the crosslinking reaction of the second-stage monomers to form a denser network structure, thus preparing the transparent PVC processing modifier; the above approximate means cooperate with each other and act synergistically, which can reduce the melt viscosity of polyvinyl chloride, improve the melt fluidity of polyvinyl chloride, improve the processing and molding performance, while improving the transparency and haze of polyvinyl chloride products, and improving their fracture toughness in a low-temperature environment; and avoid the adverse effects of the transparent PVC processing modifier on the polyvinyl chloride melt, adjust the stable processing torque, and improve the thermal stability of polyvinyl chloride products.

[0028] (2)When the transparent PVC processing modifier of the present invention is used in the preparation of PVC products, the minimum torque of the PVC melt is 21.7 - 22.3 Nm, the maximum torque is 27.6 - 28.0 Nm, the balance torque is 23.0 - 23.2 Nm, the melt factor is 0.88 - 0.91, and the fusion time is 125 - 132 s.

[0029] (3)When the transparent PVC processing modifier of the present invention is used in the preparation of PVC products, the transparency of the obtained PVC products is 91.5 - 92.0%, the haze is 1.25 - 1.30%, the notched impact strength is 37.4 - 37.7 KJ / m 2 , the tensile strength is 55.9 - 56.4 MPa, and the flexural strength is 93.1 - 93.8 MPa.

[0030] (4) The transparent PVC processing modifier of the present invention is used in the preparation of PVC products. The notched impact strength of the obtained PVC products after standing for 7 days at a temperature of -22 °C is 37.0 - 37.4 KJ / m 2 .

[0031] (5) The transparent PVC processing modifier of the present invention is used in the preparation of PVC products. After the obtained PVC products are standing for 21 days in an environment with a relative humidity of 90% and a temperature of 65 °C, the transparency is 91.1 - 91.6%, the haze is 1.27 - 1.32%, and the notched impact strength is 36.7 - 37.1 KJ / m 2 , the tensile strength is 55.1 - 55.7 MPa, and the flexural strength is 91.5 - 92.3 MPa. Detailed Embodiments

[0032] In order to have a clearer understanding of the technical features, objectives, and effects of the present invention, the detailed embodiments of the present invention are now described. It should be noted that the following detailed descriptions are all exemplary and are intended to provide further explanations of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0033] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, "first", "second", etc. are used to distinguish similar objects and are not used to describe a specific order or sequence. In addition, it should also be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or their combinations.

[0034] The embodiment of the present invention provides a preparation method of a transparent PVC processing modifier, which consists of the following steps: a first-stage reaction and a second-stage reaction.

[0035] The method of the first-stage reaction is as follows: Put deionized water and sodium dodecylbenzenesulfonate into the reaction kettle. After stirring for 5 - 10 minutes, continue to add methyl methacrylate, butyl acrylate, styrene, and vinyl acetate, and stir at 180 - 220 rpm for 10 - 20 minutes. Replace the air in the reaction kettle with nitrogen, and adjust the pressure in the reaction kettle to 0.1 - 0.12 MPa. Add an initiator (preferably potassium persulfate), and under the stirring speed of 180 - 220 rpm, stir and heat up to 62 - 68 °C, and keep stirring and reacting for 1 - 2 hours to obtain the first-stage reaction product.

[0036] In the first-stage reaction, the weight ratio of deionized water, sodium dodecylbenzenesulfonate, methyl methacrylate, butyl acrylate, styrene, vinyl acetate, and initiator is 100 - 105:0.9 - 1.1:35 - 37:8 - 8.3:5 - 5.2:1.5 - 1.6:0.3 - 0.35.

[0037] The method of the second-stage reaction is as follows: Put the first-stage reactants, butyl methacrylate, acrylonitrile, and isooctyl acrylate into the reaction kettle. After stirring at 220 - 250 rpm for 10 - 20 min, continue to add the composite modifier. After stirring for 10 - 20 min, displace the air in the reaction kettle with nitrogen, and adjust the pressure in the reaction kettle to 0.1 - 0.12 MPa. Add the initiator (preferably potassium persulfate). Under the stirring speed of 220 - 250 rpm, stir and heat up to 70 - 75 °C, keep stirring and reacting for 3 - 4 h, then cool to obtain the second-stage reactants; the second-stage reactants are spray-dried to prepare a transparent PVC processing modifier.

[0038] In the second-stage reaction, the weight ratio of the first-stage reactants, butyl methacrylate, acrylonitrile, isooctyl acrylate, composite modifier, and initiator is 100 - 105:50 - 53:16 - 17:7 - 8:7 - 7.5:0.4 - 0.45.

[0039] The preparation method of the composite modifier includes the following steps: Prepare the hyperbranched modifier and compound it.

[0040] The method of preparing the hyperbranched modifier is as follows: Put cetyl dimethyl tertiary amine and N,N-dimethylethanolamine into the reaction kettle. After stirring for 5 - 10 min, stir and heat up to 80 - 85 °C and keep warm; then drop in epichlorohydrin at a dropping rate of 0.2 - 0.4 mL / min. After the dropping of epichlorohydrin is completed, keep stirring for 4 - 5 h, then remove the unreacted epichlorohydrin by vacuum distillation to obtain the pre-reactant; Put the pre-reactant and absolute ethanol into the reaction kettle. After stirring for 15 - 30 min, continue to add the catalyst (preferably triethylamine). Stir and heat up to 80 - 85 °C and keep refluxing and reacting for 10 - 12 h to prepare the hyperbranched modifier.

[0041] In the preparation of the hyperbranched modifier, the molar amount of epichlorohydrin is 1.02 - 1.05 times the total molar amount of cetyl dimethyl tertiary amine and N,N-dimethylethanolamine;

[0042] The weight ratio of the pre-reactant to absolute ethanol is 1:0.7 - 0.8;

[0043] The added weight of the catalyst is 2 - 2.5% of the weight of the pre-reactant.

[0044] The compounding method is as follows: Place metal-organic framework ZIF-8 in a vacuum oven. Under the environment with a vacuum degree of 0.05 - 0.07 MPa, keep it at 150 - 160 °C for heat preservation and activation for 4 - 5 h, and then naturally cool it to room temperature to obtain activated ZIF-8. Then, put the activated ZIF-8 into a hyperbranched modifier, heat it up to 35 - 40 °C, keep it at a constant temperature and perform ultrasonic treatment for 30 - 50 min, and then cool it to obtain a compound modifier.

[0045] In the compounding, the ultrasonic frequency of the ultrasonic treatment is 25 - 30 KHz, and the ultrasonic power is 170 - 200 W.

[0046] The weight ratio of the activated ZIF-8 to the hyperbranched modifier is 4.2 - 4.6:100.

[0047] The embodiment of the present invention also provides a transparent PVC processing modifier, which is prepared by the aforementioned preparation method.

[0048] The following further illustrates the present invention in conjunction with some specific embodiments.

[0049] Example 1

[0050] This example provides a preparation method of a transparent PVC processing modifier, specifically as follows:

[0051] 1. First-stage reaction

[0052] Put deionized water and sodium dodecylbenzenesulfonate into the reaction kettle, stir for 5 min, then continue to put methyl methacrylate, butyl acrylate, styrene, and vinyl acetate, stir at 180 rpm for 20 min, displace the air in the reaction kettle with nitrogen, and adjust the pressure in the reaction kettle to 0.1 MPa. Put the initiator potassium persulfate, and under the stirring speed of 180 rpm, stir and heat up to 62 °C, keep stirring and reacting for 1.2 h to obtain the first-stage reaction product.

[0053] Among them, the weight ratio of deionized water, sodium dodecylbenzenesulfonate, methyl methacrylate, butyl acrylate, styrene, vinyl acetate, and potassium persulfate is 100:1.01:35:8:5:1.5:0.3.

[0054] 2. Second-stage reaction

[0055] Put a reactant, butyl methacrylate, acrylonitrile, and isooctyl acrylate into a reaction kettle. After stirring at 220 rpm for 20 min, continue to add a composite modifier. After stirring for 20 min, displace the air in the reaction kettle with nitrogen, and adjust the pressure in the reaction kettle to 0.1 MPa. Add potassium persulfate as an initiator, and while stirring at 220 rpm, heat up to 70 °C with stirring. After holding the temperature and stirring for 3 h, cool to obtain a second-stage reactant; the second-stage reactant is spray-dried to obtain a transparent PVC processing modifier.

[0056] Among them, the weight ratio of the first-stage reactant, butyl methacrylate, acrylonitrile, isooctyl acrylate, composite modifier, and potassium persulfate is 100:50:16:7:7:0.4.

[0057] The preparation method of the composite modifier includes the following steps:

[0058] 1) Prepare a hyperbranched modifier

[0059] Add cetyl dimethyl tertiary amine (0.7 mol) and N,N-dimethylethanolamine (0.2 mol) into a reaction kettle. After stirring for 5 min, heat up to 80 °C with stirring and hold the temperature; then dropwise add epichlorohydrin (0.92 mol) at a dropping rate of 0.2 mL / min. After the addition of epichlorohydrin is completed, hold the temperature and stir for 4 h, then remove the unreacted epichlorohydrin by vacuum distillation to obtain a pre-reactant; put the pre-reactant and absolute ethanol into the reaction kettle. After stirring for 15 min, continue to add triethylamine as a catalyst, heat up to 80 °C with stirring, and reflux for 10 h to obtain a hyperbranched modifier.

[0060] Among them, the weight ratio of the pre-reactant to absolute ethanol is 1:0.7.

[0061] The added weight of the catalyst triethylamine is 2% of the weight of the pre-reactant.

[0062] 2) Composite

[0063] Put metal-organic framework ZIF-8 into a vacuum oven. In an environment with a vacuum degree of 0.05 MPa, hold the temperature at 150 °C for 4 h of activation, and then naturally cool to room temperature to obtain activated ZIF-8; then put the activated ZIF-8 into the hyperbranched modifier, heat up to 35 °C, hold the temperature and perform ultrasonic treatment for 30 min, and then cool to obtain a composite modifier.

[0064] Among them, the ultrasonic frequency of the ultrasonic treatment is 25 KHz, and the ultrasonic power is 170 W.

[0065] The weight ratio of activated ZIF-8 to the hyperbranched modifier is 4.2:100.

[0066] This embodiment also provides a transparent PVC processing modifier prepared by the aforementioned method, which has a white powder appearance and an apparent density of 0.40 g / cm 3 .

[0067] Example 2

[0068] This embodiment provides a preparation method of a transparent PVC processing modifier, specifically as follows:

[0069] 1. First-stage reaction

[0070] Put deionized water and sodium dodecylbenzenesulfonate into the reaction kettle, stir for 8 min, then continue to put methyl methacrylate, butyl acrylate, styrene, and vinyl acetate. Stir at 200 rpm for 15 min, displace the air in the reaction kettle with nitrogen, and adjust the pressure in the reaction kettle to 0.11 MPa. Put in the initiator potassium persulfate, and stir and heat up to 65 °C at a stirring speed of 200 rpm, and keep stirring and reacting for 1.5 h to obtain the first-stage reaction product.

[0071] Among them, the weight ratio of deionized water, sodium dodecylbenzenesulfonate, methyl methacrylate, butyl acrylate, styrene, vinyl acetate, and potassium persulfate is 102:1.05:36:8.2:5.1:1.55:0.34.

[0072] 2. Second-stage reaction

[0073] Put the first-stage reaction product, butyl methacrylate, acrylonitrile, and isooctyl acrylate into the reaction kettle, stir at 230 rpm for 15 min, then continue to put in the composite modifier and stir for 15 min. Displace the air in the reaction kettle with nitrogen, and adjust the pressure in the reaction kettle to 0.11 MPa. Put in the initiator potassium persulfate, and stir and heat up to 72 °C at a stirring speed of 230 rpm. Keep stirring and reacting for 3.5 h, then cool to obtain the second-stage reaction product; the second-stage reaction product is spray-dried to obtain the transparent PVC processing modifier.

[0074] Among them, the weight ratio of the first-stage reaction product, butyl methacrylate, acrylonitrile, isooctyl acrylate, composite modifier, and potassium persulfate is 102:51:16.4:7.5:7.3:0.42.

[0075] The preparation method of the composite modifier includes the following steps:

[0076] 1) Prepare the hyperbranched modifier

[0077] Add cetyl dimethyl tertiary amine (0.8 mol) and N,N-dimethyl ethanolamine (0.2 mol) into the reaction kettle. After stirring for 8 min, heat up the mixture with stirring to 83 °C and keep it warm. Then, dropwise add epichlorohydrin (1.03 mol) at a dropping rate of 0.3 mL / min. After the addition of epichlorohydrin is completed, keep stirring for 4.5 h, and then remove the unreacted epichlorohydrin by vacuum distillation to obtain a pre-reactant. Put the pre-reactant and absolute ethanol into the reaction kettle. After stirring for 20 min, continue to add the catalyst triethylamine, heat up the mixture with stirring to 82 °C, and keep it refluxing for 11 h to prepare a hyperbranched modifier.

[0078] Among them, the weight ratio of the pre-reactant to absolute ethanol is 1:0.75.

[0079] The added weight of the catalyst triethylamine is 2.3% of the weight of the pre-reactant.

[0080] 2) Composite

[0081] Place metal-organic framework ZIF-8 in a vacuum oven. Under the environment of a vacuum degree of 0.06 MPa, keep it at 155 °C for activation for 4.5 h, and then naturally cool it to room temperature to obtain activated ZIF-8. Then put the activated ZIF-8 into the hyperbranched modifier, heat up to 38 °C, keep it warm and perform ultrasonic treatment for 40 min, and then cool it to prepare a composite modifier.

[0082] Among them, the ultrasonic frequency of the ultrasonic treatment is 28 KHz, and the ultrasonic power is 180 W.

[0083] The weight ratio of the activated ZIF-8 to the hyperbranched modifier is 4.5:100.

[0084] This example also provides a transparent PVC processing modifier prepared by the aforementioned method. Its appearance is white powder, and the apparent density is 0.42 g / cm 3 .

[0085] Example 3

[0086] This example provides a preparation method of a transparent PVC processing modifier, specifically as follows:

[0087] 1. One-stage reaction

[0088] Put deionized water and sodium dodecylbenzenesulfonate into the reaction kettle. After stirring for 10 min, continue to add methyl methacrylate, butyl acrylate, styrene, and vinyl acetate, and stir at 220 rpm for 10 min. Replace the air in the reaction kettle with nitrogen, and adjust the pressure in the reaction kettle to 0.12 MPa. Add the initiator potassium persulfate, and under the stirring speed of 220 rpm, heat up the mixture with stirring to 68 °C, and keep stirring and reacting for 2 h to obtain a one-stage reactant.

[0089] Among them, the weight ratio of deionized water, sodium dodecylbenzenesulfonate, methyl methacrylate, butyl acrylate, styrene, vinyl acetate, and potassium persulfate is 105:1.1:37:8.3:5.2:1.6:0.35.

[0090] 2. Second-stage reaction

[0091] Put the first-stage reactants, butyl methacrylate, acrylonitrile, and isooctyl acrylate into the reaction kettle. After stirring at 250 rpm for 10 min, continue to add the composite modifier. After stirring for 10 min, displace the air in the reaction kettle with nitrogen, and adjust the pressure in the reaction kettle to 0.12 MPa. Add the initiator potassium persulfate. Under the stirring speed of 250 rpm, stir and heat up to 75 °C, keep warm and stir for 4 h, then cool to obtain the second-stage reactants; the second-stage reactants are spray-dried to obtain a transparent PVC processing modifier.

[0092] Among them, the weight ratio of the first-stage reactants, butyl methacrylate, acrylonitrile, isooctyl acrylate, composite modifier, and potassium persulfate is 105:53:17:8:7.5:0.45.

[0093] The preparation method of the composite modifier includes the following steps:

[0094] 1) Preparation of hyperbranched modifier

[0095] Add cetyl dimethyl tertiary amine (0.8 mol) and N,N-dimethylethanolamine (0.25 mol) into the reaction kettle. After stirring for 10 min, stir and heat up to 85 °C, and keep warm; then dropwise add epichlorohydrin (1.1 mol) at a dropping rate of 0.4 mL / min. After the addition of epichlorohydrin is completed, keep warm and stir for 5 h, then remove the unreacted epichlorohydrin by vacuum distillation to obtain a pre-reactant; put the pre-reactant and absolute ethanol into the reaction kettle. After stirring for 30 min, continue to add the catalyst triethylamine, stir and heat up to 85 °C, and keep warm and reflux for 12 h to obtain the hyperbranched modifier.

[0096] Among them, the weight ratio of the pre-reactant to absolute ethanol is 1:0.8.

[0097] The added weight of the catalyst triethylamine is 2.5% of the weight of the pre-reactant.

[0098] 2) Composite

[0099] The metal-organic framework ZIF-8 was placed in a vacuum oven. After heat preservation and activation at 160 °C for 5 h in an environment with a vacuum degree of 0.07 MPa, it was naturally cooled to room temperature to obtain activated ZIF-8. Then, the activated ZIF-8 was put into a hyperbranched modifier, and the temperature was raised to 40 °C. After heat preservation and ultrasonic treatment for 50 min, it was cooled to prepare a composite modifier.

[0100] Among them, the ultrasonic frequency of the ultrasonic treatment was 30 KHz, and the ultrasonic power was 200 W.

[0101] The weight ratio of the activated ZIF-8 to the hyperbranched modifier was 4.6:100.

[0102] This example also provides a transparent PVC processing modifier prepared by the aforementioned method, which has a white powder appearance and an apparent density of 0.43 g / cm 3 .

[0103] Comparative Example 1

[0104] For the convenience of comparison, Comparative Example 1 adopted the technical solution of Example 2, and the changes made on this basis were in the preparation of the composite modifier used in the two-stage reaction process: 1) The addition of N,N-dimethylethanolamine was omitted; 2) The addition of the metal-organic framework ZIF-8 was omitted, and the hyperbranched modifier was directly used to replace the composite modifier in the two-stage reaction in equal amount.

[0105] Comparative Example 2

[0106] For the convenience of comparison, Comparative Example 2 adopted the technical solution of Example 2, and the changes made on this basis were in the preparation of the composite modifier used in the two-stage reaction process: The preparation of the hyperbranched modifier was omitted, and cetyltrimethylammonium chloride was used to replace the hyperbranched modifier to be compounded with ZIF-8 to prepare a composite modifier.

[0107] The transparent PVC processing modifiers of Examples 1-3 and Comparative Examples 1-2 were respectively used in the preparation of PVC materials. Specifically: The following raw materials for the preparation of PVC materials were prepared by weight: 100 parts of PVC, 5 parts of calcium carbonate, 3.75 parts of calcium-zinc stabilizer, 0.2 part of stearic acid, 1.5 parts of titanium dioxide, 0.15 part of oxidized polyethylene wax, and 5 parts of transparent PVC processing modifier; The raw materials were melted and mixed evenly; And the minimum torque, maximum torque, equilibrium torque, melt index, and fusion time of the PVC melt were respectively detected by a Haake torque rheometer. The specific results are shown in the following table:

[0108]

[0109] Furthermore, after the above-mentioned raw materials are respectively melted and mixed evenly, they are made into standard test specimens through plasticizing and vulcanizing. In a room-temperature environment, the transparency, haze, notched impact strength, tensile strength, and flexural strength of each specimen are detected. Among them, the detection methods for transparency and haze refer to the standard GB / T 2410-2008 "Determination of Light Transmittance and Haze of Transparent Plastics"; the detection method for notched impact strength refers to the standard GB / T 1043.1-2008 "Plastics - Determination of Charpy Impact Properties - Part 1: Non-Instrumented Impact Test"; the detection method for tensile strength refers to GB / T 1040.1-2008 "Plastics - Determination of Tensile Properties"; the detection method for flexural strength refers to GB / T 9341-2008 "Plastics - Determination of Flexural Properties". The specific results are shown in the following table:

[0110]

[0111] Furthermore, each specimen is respectively placed in a low-temperature environment at -22°C and left standing for 7 days. Then, the notched impact strength of each specimen at -22°C is detected respectively. The specific results are shown in the following table:

[0112]

[0113] Furthermore, each specimen is respectively placed in a high-temperature and high-humidity environment with a relative humidity of 90% and a temperature of 65°C and left standing for 21 days. Then, the transparency, haze, notched impact strength, tensile strength, and flexural strength of each specimen are detected respectively. The specific results are shown in the following table:

[0114]

[0115] It can be seen that in the preparation method of the transparent PVC processing modifier of the present invention, after methyl methacrylate, butyl acrylate, styrene, and vinyl acetate are used as the first-stage monomers for polymerization reaction, a first-stage reaction product is obtained; then, the first-stage reaction product, a composite modifier, and butyl methacrylate, acrylonitrile, and isooctyl acrylate as the second-stage monomers are used for polymerization reaction to obtain a second-stage reaction product, which is then spray-dried to obtain the transparent PVC processing modifier; and in the preparation of the composite modifier used, first, cetyl dimethyl tertiary amine, N,N-dimethyl ethanolamine, and epichlorohydrin are reacted. Cetyl dimethyl tertiary amine provides a hydrophobic long chain as the hydrophobic end group of the hyperbranched modifier, and N,N-dimethyl ethanolamine, as a functionalized alkyl tertiary amine, provides hydroxyl and tertiary amine groups to promote the branching reaction and increase the crosslinking density; through the cooperation of the dual active raw materials of cetyl dimethyl tertiary amine and N,N-dimethyl ethanolamine, a hyperbranched modifier with a multi-quaternary ammonium center and a multi-branched network structure is prepared by reaction; then, the hyperbranched modifier is compounded with heat-activated ZIF-8, and through the electrostatic and adsorption effects of the two, a composite modifier is prepared to improve the compatibility of the hyperbranched modifier with the second-stage monomers and improve the reaction uniformity of the subsequent second-stage polymerization; in the second-stage reaction, the composite modifier uses the metal active nodes of ZIF-8 as auxiliary initiation sites to initiate the polymerization of the second-stage monomers, and through the terminal groups of the hyperbranched modifier in the composite modifier and the surface groups of ZIF-8 participating in the crosslinking reaction of the second-stage monomers, a denser network structure is formed to prepare the transparent PVC processing modifier.

[0116] In the preparation of PVC materials, through the hyperbranched modifier component of the composite modifier in the added transparent PVC processing modifier, the entanglement and friction of molecular chains in the polyvinyl chloride melt are reduced, the fluidity of the polyvinyl chloride melt is improved, the stable melt processing torque is adjusted, the large fluctuations in the processing torque are reduced, and the uniform plasticization of polyvinyl chloride particles is promoted, the melt factor is increased, and its processing performance is improved; at the same time, through the tertiary amine groups of the hyperbranched modifier, the HCl released by the decomposition of polyvinyl chloride in a high-temperature environment is trapped, the autocatalytic decomposition effect of HCl on polyvinyl chloride is reduced, and its thermal stability is improved; and through the network structure of the hyperbranched modifier as an elastic node, it is dispersed in the PVC matrix to improve the toughness and impact resistance of polyvinyl chloride products, especially to improve its low-temperature toughness. Further, through the porous adsorption effect of the metal-organic framework ZIF-8 in the composite modifier, the free plasticizer in polyvinyl chloride and the HCl released by decomposition in a high-temperature environment are trapped, the viscosity fluctuation during the processing is reduced, the stable melt processing torque is adjusted, and the thermal stability is improved; at the same time, through its dispersion effect as a filler, the molecular chain slip is hindered, the low-temperature migration of the plasticizer is delayed, and the low-temperature toughness is improved; and through its own thermal barrier effect, the thermal stability of polyvinyl chloride products is further improved.

[0117] In Comparative Example 1, after omitting the addition of N,N-dimethylethanolamine and metal-organic framework ZIF-8 in the preparation of the composite modifier, it is impossible to prepare a hyperbranched modifier with multiple quaternary ammonium centers and a multi-branched network structure by combining N,N-dimethylethanolamine with cetyl dimethyl tertiary amine, and its improvement effect on polyvinyl chloride cannot be effectively achieved; nor can the further enhancement of the thermal stability, processing performance, and low-temperature toughness of polyvinyl chloride be achieved by combining with metal-organic framework ZIF-8. Specifically, the fluctuation of the processing torque of the PVC melt increases, and the melt index decreases; the toughness and mechanical properties of the prepared PVC products are significantly reduced; at the same time, the toughness of the PVC products in a low-temperature environment is significantly reduced; in addition, the thermal stability of the PVC products is reduced, and after standing for a long time in a high-humidity and high-temperature environment, their toughness and mechanical properties are significantly reduced.

[0118] In Comparative Example 2, after omitting the preparation of the hyperbranched modifier in the preparation of the composite modifier and using cetyl trimethyl ammonium chloride to replace the hyperbranched modifier to form a composite modifier with ZIF-8, the effective improvement of the processing performance of the PVC melt and the related properties of the PVC products cannot be achieved by the hyperbranched modifier; specifically, the processing performance indexes such as the fluctuation of the processing torque and the melt index of the PVC melt deteriorate to a certain extent, and the toughness and mechanical properties of the prepared PVC products are reduced to a certain extent; at the same time, the toughness of the PVC products in a low-temperature environment is reduced to a certain extent; in addition, the thermal stability of the PVC products is reduced, and after standing for a long time in a high-humidity and high-temperature environment, their toughness and mechanical properties are reduced to a certain extent.

[0119] Unless otherwise specified, the percentages used in the present invention are all mass percentages.

[0120] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention 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 perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of a transparent PVC processing modifier, characterized in that, It includes the following steps: a first-stage reaction and a second-stage reaction; In the first-stage reaction, deionized water, sodium dodecylbenzenesulfonate, methyl methacrylate, butyl acrylate, styrene, and vinyl acetate are mixed evenly, and then, in an inert gas environment and in the presence of an initiator, the temperature is raised for reaction to obtain a first-stage reaction product; In the second-stage reaction, the first-stage reaction product, butyl methacrylate, acrylonitrile, isooctyl acrylate, and a composite modifier are mixed evenly, and then, in an inert gas environment and in the presence of an initiator, the temperature is raised for reaction to obtain a second-stage reaction product; the second-stage reaction product is spray-dried to prepare a transparent PVC processing modifier; The preparation method of the composite modifier consists of the following steps: preparing a hyperbranched modifier and compounding; For the preparation of the hyperbranched modifier, after a pre-reaction product is obtained by reacting cetyl dimethyl tertiary amine, N,N-dimethylethanolamine, and epichlorohydrin, in a solvent environment and in the presence of a catalyst, the temperature is raised for reaction to prepare the hyperbranched modifier; For the compounding, after metal-organic framework ZIF-8 is thermally activated, the activated ZIF-8 and the hyperbranched modifier are mixed and subjected to ultrasonic treatment to prepare the composite modifier.

2. The preparation method of the transparent PVC processing modifier according to claim 1, characterized in that In the first-stage reaction, the reaction pressure is 0.1 - 0.12 MPa, the reaction temperature is 62 - 68 °C, and the reaction time is 1 - 2 h; In the second-stage reaction, the reaction pressure is 0.1 - 0.12 MPa, the reaction temperature is 70 - 75 °C, and the reaction time is 3 - 4 h.

3. The preparation method of the transparent PVC processing modifier according to claim 1, characterized in that, In the first-stage reaction, the weight ratio of deionized water, sodium dodecylbenzenesulfonate, methyl methacrylate, butyl acrylate, styrene, vinyl acetate, and the initiator is 100 - 105:0.9 - 1.1:35 - 37:8 - 8.3:5 - 5.2:1.5 - 1.6:0.3 - 0.

35.

4. The preparation method of the transparent PVC processing modifier according to claim 1, characterized in that, In the second-stage reaction, the weight ratio of the first-stage reaction product, butyl methacrylate, acrylonitrile, isooctyl acrylate, the composite modifier, and the initiator is 100 - 105:50 - 53:16 - 17:7 - 8:7 - 7.5:0.4 - 0.

45.

5. The preparation method of the transparent PVC processing modifier according to claim 1, characterized in that, For the preparation of the hyperbranched modifier, cetyl dimethyl tertiary amine and N,N-dimethylethanolamine are mixed evenly, and then the temperature is raised to 80 - 85 °C, and epichlorohydrin is added dropwise while maintaining the temperature; after the addition is completed, the mixture is stirred while maintaining the temperature for 4 - 5 h to remove the unreacted epichlorohydrin to obtain a pre-reaction product; the pre-reaction product, absolute ethanol, and the catalyst are mixed, and the reaction is carried out at 80 - 85 °C while maintaining the temperature for 10 - 12 h to prepare the hyperbranched modifier.

6. The preparation method of the transparent PVC processing modifier according to claim 1, characterized in that In the preparation of the hyperbranched modifier, the molar amount of epichlorohydrin is 1.02 - 1.05 times the total molar amount of cetyl dimethyl tertiary amine and N,N-dimethylethanolamine.

7. The preparation method of the transparent PVC processing modifier according to claim 5, characterized in that, In the preparation of the hyperbranched modifier, the weight ratio of the pre-reaction product to absolute ethanol is 1:0.7 - 0.8; The added weight of the catalyst is 2 - 2.5% of the weight of the pre-reaction product.

8. The preparation method of the transparent PVC processing modifier according to claim 1, characterized in that, In the compounding, the vacuum degree of thermal activation is 0.05 - 0.07 MPa, the thermal activation temperature is 150 - 160 °C, and the thermal activation time is 4 - 5 h; The ultrasonic treatment temperature is 35 - 40 °C, the ultrasonic treatment time is 30 - 50 min, the ultrasonic frequency is 25 - 30 KHz, and the ultrasonic power is 170 - 200 W.

9. The preparation method of the transparent PVC processing modifier according to claim 1, characterized in that, In the composite, the weight ratio of the activated ZIF-8 to the hyperbranched modifier is 4.2 - 4.6:

100.

10. A transparent PVC processing modifier, characterized in that, It is prepared by using the preparation method according to any one of claims 1 - 9.

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