Acrylate additive for PVC (polyvinyl chloride) and preparation method thereof

Abstract

The invention provides an acrylate assistant for PVC (polyvinyl chloride) and a preparation method of the acrylate assistant, and belongs to the technical field of acrylate assistants. The preparation method comprises the steps of nano montmorillonite functionalization, synthesis of a core layer, synthesis of a middle layer and synthesis of a shell layer. The synthesis step of the core layer comprises the following steps: adding a core layer emulsion into a reaction kettle, adding an ammonium persulfate solution for the first time, heating to 64-68 DEG C, adding an ammonium persulfate solution for the second time, and reacting for 48-55 minutes to obtain a functionalized core emulsion; the core layer emulsion is prepared from deionized water, functionalized nano montmorillonite, sodium allyloxy hydroxypropyl sulfonate, butyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl methylacrylate and gamma-methacryloyloxypropyltrimethoxysilane through ultrasonic treatment, and the core layer emulsion is prepared from the deionized water, the functionalized nano montmorillonite, the sodium allyloxy hydroxypropyl sulfonate, the butyl acrylate, the 2-ethylhexyl acrylate, the hydroxyethyl methylacrylate and the gamma-methacryloyloxypropyltrimethoxysilane through ultrasonic treatment; the prepared acrylate auxiliary agent is used in PVC, the fluidity can be improved, and meanwhile the impact resistance, the strength performance and the high-temperature stability performance are enhanced.

Description

Technical Field

[0001] The present invention belongs to the technical field of acrylate additives, and particularly relates to an acrylate additive for PVC and a preparation method thereof. Background Art

[0002] PVC, whose Chinese name is polyvinyl chloride, is a polymer formed by the polymerization of vinyl chloride monomers under the action of initiators such as peroxides and azo compounds, or under the action of light and heat according to the free radical polymerization reaction mechanism; as one of the most widely produced general plastics globally, polyvinyl chloride has excellent comprehensive properties and is widely used in fields such as construction, packaging, electronic appliances, and medical devices. However, defects such as poor thermal stability, insufficient processing fluidity, and poor impact resistance of PVC limit its further development. Acrylate additives have good compatibility and versatility with PVC and have become indispensable modification additives in PVC processing; acrylate additives mainly improve the impact resistance of PVC, especially the low-temperature impact resistance. It can also improve the processing fluidity of PVC, enhance weather resistance and thermal stability.

[0003] Generally speaking, acrylate additives for PVC usually improve the fluidity, impact resistance, and thermal stability of PVC by adjusting the molecular structure, adding additives, etc. However, in order to improve the fluidity of PVC, the intermolecular force is usually weakened, and the stability between molecular chains decreases, thereby reducing the impact resistance and thermal stability of PVC.

[0004] Traditional acrylate additives for PVC usually adopt emulsion polymerization method, and different properties are imparted to the additives through the design of multi-layer core-shell structure; Chinese Patent CN103467663A discloses a preparation method of an acrylate processing aid with a multi-layer gradient core-shell structure. The method includes the following process steps: (1) At 30°C and under stirring conditions, add deionized water, initiator A, emulsifier, co-emulsifier, dispersant, soft monomer, and cross-linking agent to the reaction kettle, and perform pre-emulsification treatment to obtain a pre-emulsion. (2) Heat the pre-emulsion to ≤90°C and keep it warm for reaction to obtain a soft monomer core layer emulsion. (3) Add initiator B, α-olefin, and a monomer with a solubility parameter similar to that of PVC to the soft monomer core layer emulsion, and sequentially polymerize 1-5 layers of hard polymer shells with a solubility parameter similar to that of polyvinyl chloride to obtain the product.

[0005] The PVC processing aid obtained by this method has the advantages of low price, excellent plasticization promotion effect, excellent weather resistance, and improved impact performance of the product. However, in the emulsion polymerization process of this method, a large amount of initiator is used, and the residual impurities affect the weather resistance of PVC. The impact strength of the PVC product prepared from the obtained processing aid is still low, and there are also defects such as poor fluidity and poor high-temperature stability, which limit its application in complex environments. Summary of the Invention

[0006] In order to solve the technical problems existing in the prior art, the present invention provides an acrylate-based aid for PVC and its preparation method. The obtained aid can improve the fluidity of PVC while enhancing the impact resistance and high-temperature stability.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions: A preparation method of an acrylate-based aid for PVC, including nano-montmorillonite functionalization, synthesis of the core layer, synthesis of the intermediate layer, and synthesis of the shell layer. The specific operations are as follows: 1. Nano-montmorillonite functionalization (1) Alkali treatment Put sodium-based montmorillonite into a sodium hydroxide solution with a mass 6 - 10 times that of the sodium-based montmorillonite. Raise the temperature to 70 - 75 °C, keep warm and stir for 5.8 - 6.3 h. After the stirring ends, filter out the solid matter. After washing and drying, put it into a calcination furnace, raise the temperature to 305 - 315 °C at a rate of 4.5 - 5.5 °C / min, keep warm and calcine for 2.0 - 3.0 h, and cool to room temperature with the furnace to obtain alkali-treated montmorillonite; The particle size of the sodium-based montmorillonite is 120 - 140 nm; The mass concentration of the sodium hydroxide solution is 23 - 28%; (2) Silane treatment Put the alkali-treated montmorillonite into an ethanol solution, add glycerol monostearate and triethanolamine, raise the temperature to 36 - 40 °C, stir for 25 - 35 min, then add N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, raise the temperature to 64 - 68 °C, keep warm and stir for 2.0 - 2.5 h, and obtain silane-treated montmorillonite after filtration, washing and drying; The mass ratio of the alkali-treated montmorillonite, ethanol solution, glycerol monostearate, triethanolamine, and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane is 13.5 - 14.0:100:0.5 - 0.8:0.6 - 1.0:1.2 - 1.5; The mass concentration of the ethanol solution is 26 - 30%; (3) Anhydride treatment Put the silane-treated montmorillonite into N,N-dimethylformamide, add succinic anhydride, raise the temperature to 58 - 62 °C, and keep the reaction for 4.3 - 4.7 h under a nitrogen atmosphere. After the reaction, separate and dry to obtain the anhydride-treated montmorillonite; The mass ratio of the silane-treated montmorillonite, N,N-dimethylformamide, and succinic anhydride is 12.5 - 13.0:120:4.4 - 4.8; (4)Acid chloride treatment Put the anhydride-treated montmorillonite into tetrahydrofuran, add triethylamine, cool to 0 °C in an ice-water bath, then add the acid chloride reagent, control the addition rate at 1.0 - 1.4 g / min. After the addition, raise the temperature to 26 - 30 °C and keep the reaction for 3.4 - 3.6 h. After the reaction, separate, wash, and dry to obtain the functionalized nano-montmorillonite; The mass ratio of the anhydride-treated montmorillonite, tetrahydrofuran, triethylamine, and the acid chloride reagent is 11.7 - 12.2:200:1.6 - 1.8:34 - 38; The acid chloride reagent is a mixture of acryloyl chloride and tetrahydrofuran, and the mass ratio of acryloyl chloride to tetrahydrofuran is 1:8 - 12.

[0008] 2. Synthesis of the core layer Add deionized water and functionalized nano-montmorillonite to the reaction vessel, stir evenly, add sodium allyloxyhydroxypropyl sulfonate, stir evenly, then add butyl acrylate, isooctyl acrylate, 2-hydroxyethyl methacrylate, γ-methacryloxypropyltrimethoxysilane, and perform ultrasonic treatment. The ultrasonic time is 28 - 32 min, the ultrasonic power is 106 - 115 W, and the ultrasonic frequency is 18 - 23 kHz. After the ultrasonic treatment, obtain the core layer emulsion; The mass ratio of deionized water, functionalized nano-montmorillonite, sodium allyloxyhydroxypropyl sulfonate, butyl acrylate, isooctyl acrylate, 2-hydroxyethyl methacrylate, γ-methacryloxypropyltrimethoxysilane is 300:4.4 - 4.8:1.0 - 1.2:31.2 - 31.8:13.0 - 13.5:2.2 - 2.7:1.6 - 2.0; Add the core layer emulsion to the reaction kettle, control the stirring speed at 200 - 220 rpm, then add ammonium persulfate solution for the first time, control the addition rate at 0.4 - 0.6 g / min. After the addition, raise the temperature to 64 - 68 °C and stir for 28 - 32 min. Then add ammonium persulfate solution for the second time, control the addition rate at 0.1 - 0.3 g / min, and while adding, lower the temperature to 56 - 60 °C at a rate of 0.1 - 0.3 °C / min. After the addition, stir for 48 - 55 min under a nitrogen atmosphere to obtain the functionalized core emulsion; The mass ratio of the nuclear layer emulsion, the first addition amount of ammonium persulfate solution and the second addition amount of ammonium persulfate solution is 330:13 - 18:8 - 12; The mass concentration of the ammonium persulfate solution is 0.8 - 1.2%.

[0009] 3. Synthesis of the intermediate layer Add functionalized nanometer montmorillonite to deionized water, stir evenly, then add methoxypolyethylene glycol methacrylate, stir evenly, and then add methyl methacrylate, glycidyl methacrylate and γ - methacryloxypropyltrimethoxysilane, and perform ultrasonic treatment with an ultrasonic power of 95 - 105 W and an ultrasonic frequency of 22 - 30 kHz. After the ultrasonic treatment is completed, an intermediate layer emulsion is obtained; The mass ratio of the deionized water, functionalized nanometer montmorillonite, methoxypolyethylene glycol methacrylate, methyl methacrylate, glycidyl methacrylate and γ - methacryloxypropyltrimethoxysilane is 200:2.2 - 2.5:0.6 - 1.0:15.4 - 16.0:8.0 - 8.5:2.8 - 3.2; Control the temperature of the reaction kettle containing the functionalized nuclear emulsion at 56 - 60 °C, with a stirring speed of 170 - 200 rpm. Add the intermediate layer emulsion, stir evenly, add the potassium persulfate solution, control the dropping rate at 0.23 - 0.26 g / min. After the addition is completed, raise the temperature to 66 - 70 °C and keep the temperature for reaction for 1.3 - 1.8 h to obtain the functionalized intermediate emulsion; The mass ratio of the functionalized nuclear emulsion, the intermediate layer emulsion and the potassium persulfate solution is 350:225 - 234:15 - 18; The mass concentration of the potassium persulfate solution is 1.8 - 2.2.

[0010] 4. Synthesis of the shell layer Add functionalized nanometer montmorillonite to deionized water, stir evenly, then add methyl methacrylate, styrene, γ - methacryloxypropyltrimethoxysilane, methacrylic acid and dimethylaminoethyl methacrylate, and perform ultrasonic treatment with an ultrasonic power of 110 - 130 W and an ultrasonic frequency of 20 - 25 kHz. After the ultrasonic treatment is completed, a shell layer emulsion is obtained; The mass ratio of the deionized water, functionalized nanometer montmorillonite, methyl methacrylate, styrene, γ - methacryloxypropyltrimethoxysilane, methacrylic acid and dimethylaminoethyl methacrylate is 600:1.0 - 1.2:28 - 32:12.0 - 12.5:4.0 - 4.3:4.4 - 4.8:7.2 - 7.6; Lower the temperature of the reactor containing the functionalized intermediate emulsion to 56 - 60 °C, control the stirring speed at 190 - 210 rpm, add the shell emulsion, and after stirring evenly, add the crosslinking agent solution, control the addition rate at 0.2 - 0.4 g / min. After the addition is completed, raise the temperature to 76 - 80 °C at a rate of 0.20 - 0.30 °C / min, add the adipic dihydrazide solution, control the addition time at 16 - 25 min. After the addition is completed, adjust the pH to 8.0 - 8.3, and keep the temperature for reaction for 2.3 - 2.7 h. After washing and drying, an acrylate additive for PVC is obtained; The mass ratio of the functionalized intermediate emulsion, the shell emulsion, the crosslinking agent solution, and the adipic dihydrazide solution is 600:645 - 655:32 - 38:10 - 14; The mass concentration of the adipic dihydrazide solution is 8 - 12%; The preparation method of the crosslinking agent solution is to add diacetone acrylamide to ethyl acetate and stir at 180 - 210 rpm for 28 - 35 min to obtain the crosslinking agent solution; The mass ratio of the ethyl acetate to the diacetone acrylamide is 30:2.2 - 2.5.

[0011] An acrylate additive for PVC is prepared by the aforementioned preparation method.

[0012] Compared with the prior art, the present invention has achieved the following beneficial effects: 1. The present invention uses nano - montmorillonite as the reinforcing phase. First, the montmorillonite is treated with alkali to improve its dispersibility and high - temperature stability. Then, amino groups are introduced onto the surface of montmorillonite through amino - silane to enhance its compatibility with the organic phase. Next, carboxyl groups are introduced onto the surface of montmorillonite using an anhydride reagent to provide reaction sites for subsequent acyl chlorination. By introducing acryloyl chloride, the carboxyl groups react with acryloyl chloride to form ester bonds, enhancing the interfacial strength with the organic phase and anchoring the functionalized nano - montmorillonite in the polymer network to prevent its shedding, thereby improving the impact resistance and high - temperature stability of PVC. Then, an acrylate - based additive is prepared using a core - intermediate - layer and shell structure. Butyl acrylate and isooctyl acrylate are used as soft monomers. 2 - Hydroxyethyl methacrylate has good binding properties with the functionalized nano - montmorillonite, forming a core structure with better flexibility, which can enhance the impact resistance of PVC and improve its fluidity. The intermediate layer serves as a transition layer, with methyl methacrylate as the hard monomer, forming a rigid support. The epoxy groups of glycerol methacrylate can react with the hydroxyl groups in the core structure and methacrylic acid in the shell, enhancing the interaction force between the layers. Polyethylene glycol methyl ether methacrylate can adjust the interfacial compatibility, ultimately balancing the impact resistance and dimensional stability of PVC, and enhancing strength and high - temperature stability. In the shell, styrene and dimethylaminoethyl methacrylate can improve the lubrication performance and fluidity. Methacrylic acid can bind to the chlorine atoms of PVC, enhancing the interfacial compatibility, reducing the precipitation of additives, and at the same time enhancing the stability of the cross - linked network, inhibiting the thermal movement of PVC chain segments, and improving the overall strength, high - temperature stability, and UV aging resistance. 2. For the PVC products prepared with the acrylate - based additive obtained in the present invention, the melt index is 7.3 - 7.8 g / 10 min, the plasticizing time is 73 - 78 s, the equilibrium torque is 20.3 - 22.5 N·m, the tensile strength is 24.1 - 26.4 MPa, the elongation at break is 387 - 398%, and the notched impact strength is 20.2 - 21.7 kJ / m 2 ; 3. For the PVC products prepared with the acrylate - based additive obtained in the present invention, after standing at 90 °C for 240 h and then measuring again, the tensile strength is 23.3 - 25.8 MPa, the elongation at break is 376 - 391%, and the notched impact strength is 19.4 - 21.1 kJ / m 2 ; 4. For the PVC products prepared with the acrylate - based additive obtained in the present invention, when subjected to UV irradiation with a UV intensity of 80 W / m 2The irradiation temperature was 60 °C, the irradiation time was 6 h, then the UV irradiation was stopped, and deionized water was sprayed. The spraying mass of deionized water was 4 times the mass of the PVC test specimen to ensure uniform coverage of the deionized water on the surface of the PVC test specimen without local dry areas. After spraying, it was left standing for 6.0 h; the above operations were one treatment cycle. After continuously performing 20 treatment cycles, the tensile strength was measured again to be 22.7 - 25.2 MPa, the elongation at break was 366 - 381%, and the notched impact strength was 18.9 - 20.5 kJ / m 2 。 Specific Embodiments

[0013] For a clearer understanding of the technical features, objectives, and effects of the present invention, the specific embodiments of the present invention are described below.

[0014] Example 1 1. Functionalization of Nano-Montmorillonite (1) Alkali Treatment Sodium montmorillonite was added to an 8-fold mass of 25 wt% sodium hydroxide solution, the temperature was raised to 72 °C, and it was kept stirring for 6.0 h. After stirring, the solid was filtered out, washed and dried, and then put into a calcination furnace. The temperature was raised to 310 °C at a rate of 5.0 °C / min, kept calcining for 2.5 h, and cooled to room temperature with the furnace to obtain alkali-treated montmorillonite; The particle size of the sodium montmorillonite was 130 nm; (2) Silane Treatment 13.8 g of alkali-treated montmorillonite was added to 100 g of 27 wt% ethanol solution, 0.6 g of glycerol monostearate and 0.8 g of triethanolamine were added, the temperature was raised to 38 °C, and it was stirred for 30 min. Then 1.4 g of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane was added, the temperature was raised to 66 °C, and it was kept stirring for 2.2 h. After filtration, washing and drying, silane-treated montmorillonite was obtained; (3) Anhydride Treatment 12.7 g of silane-treated montmorillonite was added to 120 g of N,N-dimethylformamide, 4.6 g of succinic anhydride was added, the temperature was raised to 60 °C, and it was kept reacting for 4.5 h under a nitrogen atmosphere. After the reaction, it was separated and dried to obtain anhydride-treated montmorillonite; (4) Acyl Chloride Treatment 12.0 g of anhydride-treated montmorillonite was added to 200 g of tetrahydrofuran, 1.7 g of triethylamine was added, and it was cooled to 0 °C in an ice-water bath. Then 35 g of acyl chloride reagent was added, and the addition rate was controlled at 1.2 g / min. After the addition was completed, the temperature was raised to 28 °C, and it was kept reacting for 3.5 h. After the reaction, it was separated, washed and dried to obtain functionalized nano-montmorillonite; The acyl chloride reagent is a mixture of acryloyl chloride and tetrahydrofuran, and the mass ratio of acryloyl chloride to tetrahydrofuran is 1:10.

[0015] 2. Synthesis of the core layer Add 300 g of deionized water and 4.6 g of functionalized nanometer montmorillonite into a reaction vessel. After stirring evenly, add 1.1 g of allyloxyhydroxypropyl sulfonate sodium. After stirring evenly, add 31.6 g of butyl acrylate, 13.3 g of isooctyl acrylate, 2.6 g of 2-hydroxyethyl methacrylate, and 1.8 g of γ-methacryloxypropyltrimethoxysilane, and perform ultrasonic treatment. The ultrasonic time is 30 min, the ultrasonic power is 110 W, and the ultrasonic frequency is 20 kHz. After the ultrasonic treatment is completed, a core layer emulsion is obtained; Add 330 g of the core layer emulsion into a reaction kettle, control the stirring speed to 210 rpm, then add 15 g of 1.0 wt% ammonium persulfate solution, control the addition rate to 0.5 g / min. After the addition is completed, raise the temperature to 66 °C and keep stirring for 30 min. Then add 10 g of 1.0 wt% ammonium persulfate solution, control the addition rate to 0.2 g / min, and while adding, lower the temperature to 58 °C at a rate of 0.2 °C / min. After the addition is completed, keep stirring for 50 min. The reaction atmosphere is nitrogen, and a functionalized core emulsion is obtained.

[0016] 3. Synthesis of the intermediate layer Add 2.3 g of functionalized nanometer montmorillonite into 200 g of deionized water. After stirring evenly, add 0.8 g of methoxypolyethylene glycol methacrylate. After stirring evenly, add 15.7 g of methyl methacrylate, 8.2 g of glycidyl methacrylate, and 3.0 g of γ-methacryloxypropyltrimethoxysilane, and perform ultrasonic treatment. The ultrasonic power is 100 W and the ultrasonic frequency is 25 kHz. After the ultrasonic treatment is completed, an intermediate layer emulsion is obtained; Control the temperature of the reaction kettle containing 350 g of the functionalized core emulsion to 58 °C, the stirring speed to 180 rpm, add 230 g of the intermediate layer emulsion, stir evenly, add 16 g of 2.0 wt% potassium persulfate solution, control the dropping rate to 0.25 g / min. After the addition is completed, raise the temperature to 68 °C and keep reacting for 1.5 h to obtain a functionalized intermediate emulsion.

[0017] 4. Synthesis of the shell layer Add 1.1 g of functionalized nanometer montmorillonite into 600 g of deionized water. After stirring evenly, add 30 g of methyl methacrylate, 12.3 g of styrene, 4.2 g of γ-methacryloxypropyltrimethoxysilane, 4.6 g of methacrylic acid, and 7.4 g of dimethylaminoethyl methacrylate, and perform ultrasonic treatment. The ultrasonic power is 120 W and the ultrasonic frequency is 22 kHz. After the ultrasonic treatment is completed, a shell layer emulsion is obtained; Lower the temperature of the reactor containing 600 g of functionalized intermediate milk to 58 °C, control the stirring speed at 200 rpm, add 650 g of shell emulsion, and after stirring evenly, add 35 g of crosslinking agent solution, control the addition rate at 0.3 g / min. After the addition is completed, raise the temperature to 78 °C at a rate of 0.25 °C / min, add 12 g of 10 wt% adipic dihydrazide solution, control the addition time at 20 min. After the addition is completed, adjust the pH to 8.2, keep the temperature for reaction for 2.5 h, and after washing and drying, obtain the acrylate additive for PVC; The preparation method of the crosslinking agent solution is as follows: add 2.3 g of diacetone acrylamide to 30 g of ethyl acetate, stir at 200 rpm for 30 min to obtain the crosslinking agent solution.

[0018] Example 2 1. Nanomontmorillonite functionalization (1) Alkali treatment Put sodium montmorillonite into a 28 wt% sodium hydroxide solution with 6 times the mass, raise the temperature to 70 °C, keep stirring for 5.8 h. After the stirring ends, filter out the solid matter, wash and dry it, then put it into a calcination furnace, raise the temperature to 305 °C at a rate of 4.5 °C / min, keep the temperature for calcination for 3.0 h, and cool it to room temperature with the furnace to obtain alkali-treated montmorillonite; The particle size of the sodium montmorillonite is 120 nm; (2) Silane treatment Put 13.5 g of alkali-treated montmorillonite into 100 g of 26 wt% ethanol solution, add 0.5 g of glycerol monostearate and 0.6 g of triethanolamine, raise the temperature to 36 °C, stir for 35 min, then add 1.2 g of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, raise the temperature to 64 °C, keep stirring for 2.0 h, and after filtration, washing and drying, obtain silane-treated montmorillonite; (3) Anhydride treatment Put 12.5 g of silane-treated montmorillonite into 120 g of N,N-dimethylformamide, add 4.4 g of succinic anhydride, raise the temperature to 58 °C, and keep the reaction under nitrogen atmosphere for 4.3 h. After the reaction ends, obtain anhydride-treated montmorillonite after separation and drying; (4) Acyl chlorination treatment Put 11.7 g of anhydride-treated montmorillonite into 200 g of tetrahydrofuran, add 1.6 g of triethylamine, cool it to 0 °C in an ice-water bath, then add 34 g of acyl chlorination reagent, control the addition rate at 1.0 g / min. After the addition is completed, raise the temperature to 26 °C, keep the reaction for 3.4 h. After the reaction ends, obtain functionalized nanomontmorillonite after separation, washing and drying; The acylating reagent is a mixture of acryloyl chloride and tetrahydrofuran, and the mass ratio of acryloyl chloride to tetrahydrofuran is 1:8.

[0019] 2. Synthesis of the core layer Add 300 g of deionized water and 4.4 g of functionalized nanometer montmorillonite into a reaction vessel. After stirring evenly, add 1.0 g of allyloxyhydroxypropyl sulfonate. After stirring evenly, add 31.2 g of butyl acrylate, 13.0 g of isooctyl acrylate, 2.2 g of 2-hydroxyethyl methacrylate, and 1.6 g of γ-methacryloxypropyltrimethoxysilane, and carry out ultrasonic treatment. The ultrasonic time is 28 min, the ultrasonic power is 106 W, and the ultrasonic frequency is 18 kHz. After the ultrasonic treatment is completed, a core layer emulsion is obtained; Add 330 g of the core layer emulsion into a reaction kettle, control the stirring speed to 200 rpm, then add 13 g of 0.8 wt% ammonium persulfate solution, control the addition rate to 0.4 g / min. After the addition is completed, raise the temperature to 64 °C and keep stirring for 32 min. Then add 8 g of 0.8 wt% ammonium persulfate solution, control the addition rate to 0.1 g / min, and while adding, lower the temperature to 56 °C at a rate of 0.1 °C / min. After the addition is completed, keep stirring for 55 min. The reaction atmosphere is nitrogen throughout, and a functionalized core emulsion is obtained.

[0020] 3. Synthesis of the intermediate layer Add 2.2 g of functionalized nanometer montmorillonite into 200 g of deionized water. After stirring evenly, add 0.6 g of methoxypolyethylene glycol methacrylate. After stirring evenly, add 15.4 g of methyl methacrylate, 8.0 g of glycidyl methacrylate, and 2.8 g of γ-methacryloxypropyltrimethoxysilane, and carry out ultrasonic treatment. The ultrasonic power is 95 W and the ultrasonic frequency is 30 kHz. After the ultrasonic treatment is completed, an intermediate layer emulsion is obtained; Control the temperature of the reaction kettle containing 350 g of the functionalized core emulsion to 56 °C, the stirring speed to 170 rpm, add 225 g of the intermediate layer emulsion, stir evenly, add 15 g of 1.8 wt% potassium persulfate solution, control the dropping rate to 0.23 g / min. After the addition is completed, raise the temperature to 66 °C and keep the reaction for 1.8 h to obtain a functionalized intermediate emulsion.

[0021] 4. Synthesis of the shell layer Add 1.0 g of functionalized nanometer montmorillonite into 600 g of deionized water. After stirring evenly, add 28 g of methyl methacrylate, 12.0 g of styrene, 4.0 g of γ-methacryloxypropyltrimethoxysilane, 4.4 g of methacrylic acid, and 7.2 g of dimethylaminoethyl methacrylate, and carry out ultrasonic treatment. The ultrasonic power is 110 W and the ultrasonic frequency is 20 kHz. After the ultrasonic treatment is completed, a shell layer emulsion is obtained; Lower the temperature of the reactor containing 600 g of functionalized intermediate emulsion to 56 °C, control the stirring speed at 190 rpm, add 645 g of shell emulsion, after stirring evenly, add 32 g of crosslinking agent solution, control the addition rate at 0.2 g / min, after the addition is completed, raise the temperature to 76 °C at a rate of 0.20 °C / min, add 10 g of 8 wt% adipic dihydrazide solution, control the addition time at 16 min, after the addition is completed, adjust the pH to 8.0, keep the temperature for reaction for 2.7 h, after washing and drying, obtain the acrylate additive for PVC; The preparation method of the crosslinking agent solution is as follows: add 2.2 g of diacetone acrylamide to 30 g of ethyl acetate, stir at 180 rpm for 35 min to obtain the crosslinking agent solution.

[0022] Example 3 1. Functionalization of nano-montmorillonite (1)Alkali treatment Put sodium montmorillonite into 10 times the mass of 23 wt% sodium hydroxide solution, raise the temperature to 75 °C, keep stirring for 6.3 h, after stirring ends, filter out the solid matter, after washing and drying, put it into a calcination furnace, raise the temperature to 315 °C at a rate of 5.5 °C / min, keep the temperature for calcination for 2.0 h, and cool to room temperature with the furnace to obtain alkali-treated montmorillonite; The particle size of the sodium montmorillonite is 140 nm; (2)Silane treatment Put 14.0 g of alkali-treated montmorillonite into 100 g of 30 wt% ethanol solution, add 0.8 g of glycerol monostearate and 1.0 g of triethanolamine, raise the temperature to 40 °C, stir for 25 min, then add 1.5 g of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, raise the temperature to 68 °C, keep stirring for 2.5 h, after filtration, washing and drying, obtain silane-treated montmorillonite; (3)Anhydride treatment Put 13.0 g of silane-treated montmorillonite into 120 g of N, N-dimethylformamide, add 4.8 g of succinic anhydride, raise the temperature to 62 °C, keep the temperature for reaction for 4.7 h under nitrogen atmosphere, after the reaction ends, obtain anhydride-treated montmorillonite after separation and drying; (4)Acyl chlorination treatment Put 12.2 g of anhydride-treated montmorillonite into 200 g of tetrahydrofuran, add 1.8 g of triethylamine, cool to 0 °C in an ice-water bath, then add 38 g of acyl chlorination reagent, control the addition rate at 1.4 g / min, after the addition is completed, raise the temperature to 30 °C, keep the temperature for reaction for 3.6 h, after the reaction ends, obtain functionalized nano-montmorillonite after separation, washing and drying; The acyl chloride reagent is a mixture of acryloyl chloride and tetrahydrofuran, and the mass ratio of acryloyl chloride to tetrahydrofuran is 1:12.

[0023] 2. Synthesis of the core layer Add 300 g of deionized water and 4.8 g of functionalized nanoclay to a reaction vessel. After stirring evenly, add 1.2 g of allyloxyhydroxypropyl sulfonate. After stirring evenly, add 31.8 g of butyl acrylate, 13.5 g of isooctyl acrylate, 2.7 g of 2-hydroxyethyl methacrylate, and 2.0 g of γ-methacryloxypropyltrimethoxysilane, and perform ultrasonic treatment. The ultrasonic time is 32 min, the ultrasonic power is 115 W, and the ultrasonic frequency is 23 kHz. After the ultrasonic treatment is completed, a core layer emulsion is obtained. Add 330 g of the core layer emulsion to a reaction kettle, control the stirring speed to 220 rpm, then add 18 g of a 1.2 wt% ammonium persulfate solution, control the addition rate to 0.6 g / min. After the addition is completed, raise the temperature to 68 °C and keep stirring for 28 min. Then add 12 g of a 1.2 wt% ammonium persulfate solution, control the addition rate to 0.3 g / min, and while adding, lower the temperature to 60 °C at a rate of 0.3 °C / min. After the addition is completed, keep stirring for 48 min. The reaction atmosphere is nitrogen throughout, and a functionalized core emulsion is obtained.

[0024] 3. Synthesis of the intermediate layer Add 2.5 g of functionalized nanoclay to 200 g of deionized water. After stirring evenly, add 1.0 g of methoxypolyethylene glycol methacrylate. After stirring evenly, add 16.0 g of methyl methacrylate, 8.5 g of glycidyl methacrylate, and 3.2 g of γ-methacryloxypropyltrimethoxysilane, and perform ultrasonic treatment. The ultrasonic power is 105 W and the ultrasonic frequency is 22 kHz. After the ultrasonic treatment is completed, an intermediate layer emulsion is obtained. Control the temperature of the reaction kettle containing 350 g of the functionalized core emulsion to 60 °C, the stirring speed to 200 rpm, add 234 g of the intermediate layer emulsion, stir evenly, add 18 g of a 2.2 wt% potassium persulfate solution, control the dropping rate to 0.26 g / min. After the addition is completed, raise the temperature to 70 °C and keep reacting for 1.3 h to obtain a functionalized intermediate emulsion.

[0025] 4. Synthesis of the shell layer Add 1.2 g of functionalized nanoclay to 600 g of deionized water. After stirring evenly, add 32 g of methyl methacrylate, 12.5 g of styrene, 4.3 g of γ-methacryloxypropyltrimethoxysilane, 4.8 g of methacrylic acid, and 7.6 g of dimethylaminoethyl methacrylate, and perform ultrasonic treatment. The ultrasonic power is 130 W and the ultrasonic frequency is 25 kHz. After the ultrasonic treatment is completed, a shell layer emulsion is obtained. Lower the temperature of the reactor containing 600 g of functionalized intermediate emulsion to 60 °C, control the stirring speed at 210 rpm, add 655 g of shell emulsion, after stirring evenly, add 38 g of crosslinking agent solution, control the addition rate at 0.4 g / min, after the addition is completed, raise the temperature to 80 °C at a rate of 0.30 °C / min, add 14 g of 12 wt% adipic dihydrazide solution, control the addition time at 25 min, after the addition is completed, adjust the pH to 8.3, keep the temperature for reaction for 2.3 h, and after washing and drying, obtain the acrylate additive for PVC; The preparation method of the crosslinking agent solution is as follows: add 2.5 g of diacetone acrylamide to 30 g of ethyl acetate and stir at 210 rpm for 28 min to obtain the crosslinking agent solution.

[0026] Comparative Example 1 Based on Example 1, the changes are as follows: 1. In the step of functionalizing nano-montmorillonite, omit the silane treatment, anhydride treatment and acyl chloride treatment steps, and the alkali-treated montmorillonite obtained in the alkali treatment step is the functionalized nano-montmorillonite; In the steps of synthesizing the core layer, intermediate layer and shell layer, replace the functionalized nano-montmorillonite with alkali-treated montmorillonite in equal amounts; 2. Omit the step of synthesizing the intermediate layer; in the step of synthesizing the shell layer, replace the functionalized intermediate emulsion with the core layer emulsion in equal amounts; The remaining operations are the same.

[0027] Comparative Example 2 Based on Example 1, the changes are as follows: 1. In the step of functionalizing nano-montmorillonite, omit the anhydride treatment and acyl chloride treatment steps, and the silane-treated montmorillonite obtained in the silane treatment step is the functionalized nano-montmorillonite; In the steps of synthesizing the core layer, intermediate layer and shell layer, replace the functionalized nano-montmorillonite with silane-treated montmorillonite in equal amounts; 2. In the step of synthesizing the core layer, replace both allyloxyhydroxypropyl sulfonate and γ-methacryloxypropyltrimethoxysilane with deionized water in equal amounts; 3. In the step of synthesizing the shell layer, replace both γ-methacryloxypropyltrimethoxysilane and dimethylaminoethyl methacrylate with deionized water in equal amounts; The remaining operations are the same.

[0028] Application Performance Prepare PVC products with the acrylate additives for PVC prepared in Examples 1 - 3 and Comparative Examples 1 - 2 according to the following formula:

[0029] After mixing the above raw materials evenly, place them in a twin-screw extruder for melt extrusion. Control the extrusion temperatures at 140°C, 160°C, 170°C, and 175°C respectively, and the screw speed at 220 rpm. After cooling and shaping, obtain the PVC test specimens.

[0030] 1. Basic properties Perform performance tests on the test specimens obtained by the above method as follows:

[0031] 2. High-temperature stability Let the PVC test specimens prepared in Examples 1-3 and Comparative Examples 1-2 stand at 90°C for 240 h. After the standing is completed, test the mechanical properties again. The results are as follows:

[0032] 3. Aging resistance Irradiate the PVC test specimens prepared in Examples 1-3 and Comparative Examples 1-2 with ultraviolet light. The ultraviolet intensity is 80 W / m 2 , the irradiation temperature is 60°C, and the irradiation time is 6.0 h. Then stop the ultraviolet irradiation and spray deionized water. The spraying mass of the deionized water is 4 times the mass of the PVC test specimen to ensure uniform coverage of the deionized water on the surface of the PVC test specimen without local dry areas. After the spraying is completed, let it stand for 6.0 h; the above operations are one treatment cycle. After continuously performing 20 treatment cycles, test the mechanical properties again. The results are as follows:

[0033] The present invention uses nano-montmorillonite as the reinforcing phase. First, the montmorillonite is treated with alkali to improve its dispersibility and high-temperature stability. Then, amino groups are introduced onto the surface of the montmorillonite through amino silane to enhance its compatibility with the organic phase. Next, carboxyl groups are introduced onto the surface of the montmorillonite using an acid anhydride reagent to provide reaction sites for subsequent acyl chlorination. By introducing acryloyl chloride, the carboxyl groups react with acryloyl chloride to form ester bonds, enhancing the interfacial strength with the organic phase and anchoring the functionalized nano-montmorillonite in the polymer network to prevent its detachment, thereby improving the impact resistance and high-temperature stability of PVC. Then, acrylate additives are prepared using a core-layer - intermediate-layer and shell-layer structure. Butyl acrylate and isooctyl acrylate are used as soft monomers. 2-Hydroxyethyl methacrylate has good binding properties with the functionalized nano-montmorillonite, forming a core structure with better flexibility, which can enhance the impact resistance of PVC and improve its fluidity. The intermediate layer serves as a transition layer, with methyl methacrylate as a hard monomer to form a rigid support. The epoxy groups of glycerol methacrylate can react with the hydroxyl groups in the core-layer structure and methacrylic acid in the shell layer, enhancing the interaction force between the layers. Polyethylene glycol methyl ether methacrylate can adjust the interfacial compatibility, ultimately balancing the impact resistance and dimensional stability of PVC, and enhancing strength and high-temperature stability. In the shell layer, styrene and dimethylaminoethyl methacrylate can improve the lubrication performance and fluidity. Methacrylic acid can bind to the chlorine atoms of PVC, enhancing the interfacial compatibility, reducing the precipitation of additives, and simultaneously enhancing the stability of the crosslinked network, inhibiting the thermal movement of PVC segments, and improving the overall strength, high-temperature stability, and UV aging resistance.

[0034] In Comparative Example 1, only alkali-treated montmorillonite is used in the core layer and the shell layer. Its compatibility with the acrylate polymer is poor and it is prone to agglomeration, thereby increasing the melt viscosity and reducing the fluidity of the PVC product. The preparation of the intermediate layer is omitted, the core-shell structure is incomplete, the stress transfer efficiency is low, the strength performance decreases, and the stability is poor in high-temperature and UV aging environments, with a low strength retention rate. In Comparative Example 2, only the alkali treatment and silane treatment steps are applied to the montmorillonite, reducing the interfacial bonding with PVC. γ-Methacryloyloxypropyltrimethoxysilane is omitted in the core layer and the shell layer, weakening the stability of the polymerization network. Also, sodium allyloxyhydroxypropylsulfonate is omitted in the core layer, reducing the crosslinking uniformity of the core layer. Dimethylaminoethyl methacrylate is omitted in the shell layer, which reduces the fluidity, ultimately decreasing the strength and stability of the PVC product.

[0035] Unless otherwise specified, the percentages used in the present invention are all mass percentages.

[0036] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not used 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 recorded in the foregoing embodiments or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of an acrylate auxiliary agent for PVC, characterized in that, It includes nanometer montmorillonite functionalization, synthesis of the core layer, synthesis of the intermediate layer, and synthesis of the shell layer; In the nanometer montmorillonite functionalization step, sodium montmorillonite is successively subjected to alkali treatment, silane treatment, anhydride treatment, and acyl chlorination treatment to obtain functionalized nanometer montmorillonite; In the synthesis step of the core layer, a core layer emulsion is added to a reaction kettle, ammonium persulfate solution is added for the first time, the temperature is raised to 64 - 68 °C, ammonium persulfate solution is added for the second time, and reaction is carried out for 48 - 55 min to obtain functionalized core emulsion; The core layer emulsion is prepared by ultrasonic treatment from deionized water, functionalized nanometer montmorillonite, allyloxyhydroxypropyl sulfonate sodium, butyl acrylate, isooctyl acrylate, 2-hydroxyethyl methacrylate, γ-methacryloxypropyltrimethoxysilane; In the synthesis step of the intermediate layer, the functionalized core emulsion and the intermediate layer emulsion are stirred evenly, potassium persulfate solution is added, and reaction is carried out at 66 - 70 °C for 1.3 - 1.8 h to obtain functionalized intermediate emulsion; The intermediate layer emulsion is prepared by ultrasonic treatment from deionized water, functionalized nanometer montmorillonite, polyethylene glycol methyl ether methacrylate, methyl methacrylate, glycidyl methacrylate, and γ-methacryloxypropyltrimethoxysilane; In the synthesis step of the shell layer, the temperature of the functionalized intermediate emulsion is lowered to 56 - 60 °C, the shell layer emulsion and a crosslinking agent solution are added, the temperature is raised to 76 - 80 °C, adipic dihydrazide solution is added, and reaction is carried out for 2.3 - 2.7 h to obtain an acrylate additive for PVC; The shell layer emulsion is prepared by ultrasonic treatment from deionized water, functionalized nanometer montmorillonite, methyl methacrylate, styrene, γ-methacryloxypropyltrimethoxysilane, methacrylic acid, and dimethylaminoethyl methacrylate.

2. The preparation method of an acrylate additive for PVC according to claim 1, characterized in that In the synthesis step of the core layer, when adding ammonium persulfate solution for the first time, the addition rate is 0.4 - 0.6 g / min; When adding ammonium persulfate solution for the second time, the addition rate is 0.1 - 0.3 g / min, and while adding, the temperature is lowered to 56 - 60 °C at a rate of 0.1 - 0.3 °C / min; The mass ratio of the core layer emulsion, the first addition amount of ammonium persulfate solution, and the second addition amount of ammonium persulfate solution is 330:13 - 18:8 - 12; The mass concentration of the ammonium persulfate solution is 0.8 - 1.2%.

3. The preparation method of an acrylate additive for PVC according to claim 2, characterized in that In the core layer emulsion, the mass ratio of deionized water, functionalized nanometer montmorillonite, allyloxyhydroxypropyl sulfonate sodium, butyl acrylate, isooctyl acrylate, 2-hydroxyethyl methacrylate, γ-methacryloxypropyltrimethoxysilane is 300:4.4 - 4.8:1.0 - 1.2:31.2 - 31.8:13.0 - 13.5:2.2 - 2.7:1.6 - 2.

0.

4. The preparation method of an acrylate additive for PVC according to claim 1, characterized in that In the synthesis step of the intermediate layer, the mass ratio of the functionalized core emulsion, the intermediate layer emulsion, and the potassium persulfate solution is 350:225 - 234:15 - 18; The mass concentration of the potassium persulfate solution is 1.8 - 2.2; In the intermediate layer emulsion, the mass ratio of deionized water, functionalized nano - montmorillonite, polyethylene glycol methyl ether methacrylate, methyl methacrylate, glycidyl methacrylate, and γ - methacryloyloxypropyltrimethoxysilane is 200:2.2 - 2.5:0.6 - 1.0:15.4 - 16.0:8.0 - 8.5:2.8 - 3.

2.

5. The preparation method of an acrylate - type auxiliary for PVC according to claim 1, characterized in that In the synthesis step of the shell layer, the mass ratio of the functionalized intermediate emulsion, the shell layer emulsion, the cross - linker solution, and the adipic dihydrazide solution is 600:645 - 655:32 - 38:10 - 14; The mass concentration of the adipic dihydrazide solution is 8 - 12%; The preparation method of the cross - linker solution is to add diacetone acrylamide to ethyl acetate and stir at 180 - 210 rpm for 28 - 35 min to obtain the cross - linker solution; The mass ratio of ethyl acetate to diacetone acrylamide is 30:2.2 - 2.

5.

6. The preparation method of an acrylate - type auxiliary for PVC according to claim 5, characterized in that In the shell layer emulsion, the mass ratio of deionized water, functionalized nano - montmorillonite, methyl methacrylate, styrene, γ - methacryloyloxypropyltrimethoxysilane, methacrylic acid, and dimethylaminoethyl methacrylate is 600:1.0 - 1.2:28 - 32:12.0 - 12.5:4.0 - 4.3:4.4 - 4.8:7.2 - 7.

6.

7. The preparation method of an acrylate - type auxiliary for PVC according to claim 1, characterized in that In the nano - montmorillonite functionalization step, the alkali treatment step is to put sodium - based montmorillonite into a sodium hydroxide solution, raise the temperature to 70 - 75 °C, keep warm and stir for 5.8 - 6.3 h. After stirring, filter out the solid matter, wash and dry it, then put it into a calcination furnace, raise the temperature at a rate of 4.5 - 5.5 °C / min to 305 - 315 °C, keep warm and calcine for 2.0 - 3.0 h, and cool it to room temperature with the furnace to obtain alkali - treated montmorillonite; The particle size of the sodium - based montmorillonite is 120 - 140 nm; The silane treatment step is to put the alkali - treated montmorillonite into an ethanol solution, add glycerol monostearate and triethanolamine, raise the temperature to 36 - 40 °C, stir for 25 - 35 min, then add N-(2 - aminoethyl)-3 - aminopropyltrimethoxysilane, raise the temperature to 64 - 68 °C, keep warm and stir for 2.0 - 2.5 h, and obtain silane - treated montmorillonite after filtration, washing and drying. The mass ratio of the alkali-treated montmorillonite, ethanol solution, glycerol monostearate, triethanolamine, and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane is 13.5 - 14.0:100:0.5 - 0.8:0.6 - 1.0:1.2 - 1.5; The mass concentration of the ethanol solution is 26 - 30%.

8. The preparation method of an acrylate-based auxiliary for PVC according to claim 7, wherein In the step of functionalizing the nano-montmorillonite, the acid anhydride treatment step is as follows: Put the silane-treated montmorillonite into N,N-dimethylformamide, add succinic anhydride, raise the temperature to 58 - 62 °C, and keep the reaction at this temperature for 4.3 - 4.7 h under a nitrogen atmosphere. After the reaction is completed, separate and dry to obtain the acid anhydride-treated montmorillonite; The mass ratio of the silane-treated montmorillonite, N,N-dimethylformamide, and succinic anhydride is 12.5 - 13.0:120:4.4 - 4.8; The acyl chlorination treatment step is as follows: Put the acid anhydride-treated montmorillonite into tetrahydrofuran, add triethylamine, cool it to 0 °C in an ice-water bath, then add the acyl chlorination reagent, control the addition rate at 1.0 - 1.4 g / min. After the addition is completed, raise the temperature to 26 - 30 °C and keep the reaction for 3.4 - 3.6 h. After the reaction is completed, separate, wash, and dry to obtain the functionalized nano-montmorillonite; The mass ratio of the acid anhydride-treated montmorillonite, tetrahydrofuran, triethylamine, and acyl chlorination reagent is 11.7 - 12.2:200:1.6 - 1.8:34 - 38; The acyl chlorination reagent is a mixture of acryloyl chloride and tetrahydrofuran, and the mass ratio of acryloyl chloride to tetrahydrofuran is 1:8 - 12.

9. An acrylate-based auxiliary for PVC prepared by the preparation method according to any one of claims 1 - 8.

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